DETAILED ACTION
Response to Arguments
Applicant’s arguments with respect to the claims have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument, produced below.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 15-17 and 33-35 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claims 15-17 and 33-35 all recite the limitation "the first structure" in the first lines of each claim. The amended claim 1 had removed the first structure to be a “shroud”. It is now unclear what is defined as “the first structure”. There is insufficient antecedent basis for this limitation in the claim. In this action, it will be assumed these limitations are referring to the shroud of the amended claim 1.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-16, 18-34, and 36-38 are rejected under 35 U.S.C. 103 as being unpatentable over Iwamoto et al. (US Pat. 9,883,574, hereinafter Iwamoto) in view of Mestrom et al. (US Pat. 8,598,551, hereinafter Mestrom).
Regarding claim 1, Iwamoto discloses a droplet generator for generating a stream of droplets of EUV source material (target producing apparatus 275 includes droplet supply device 260, see Fig. 2 and col. 6, lines 28-37; droplets 27 generates plasma from laser light pulse 33 to generate EUV light, see Fig. 2 and col. 5, lines 43-50), the droplet generator comprising:
a nozzle adapted to emit a stream of liquid EUV source material from a nozzle outlet (droplet supply device 260 stores liquid droplet material 260 in a tank 61, see Fig. 2 and col. 4, lines 50-57; target controller 51 sets a frequency to produce a jet 277 of the droplet material from the projection 265 at a predetermined speed, see col. 7, lines 4-15; droplets of liquid target used to form a plasma for EUV generation, see col. 5, lines 43-50);
at least one inlet adapted to be connected to a source of a gas and arranged to introduce a flow of gas into the droplet generator (gas lock cover 410 has a buffer space 430 connected to a channel 404 for a lock gas, see Fig. 7A and col. 12, lines 7-12);
a shroud defining a droplet coalescence zone, extending downstream from the nozzle outlet to a first location, in which the stream of liquid EUV source material breaks up and coalesces into a stream of coalesced droplets of liquid EUV source material, the shroud being arranged to protect the stream of liquid EUV source material from the flow of gas introduced from the at least one inlet while the liquid EUV source material is in the droplet coalescence zone (zone below the nozzle 660, surrounded by the gas lock 410, protects the target material along the droplet trajectory 272 from the gas of the gas lock 410 introduced to the droplets from the gas outlets 702, see Fig. 7A).
Iwamoto fails to disclose a second structure defining a gas acceleration zone, extending downstream from the first location to a second location, in fluid communication with the inlet, arranged to receive the stream of droplets at the first location, and adapted to cause the gas to be introduced into the gas zone downstream of the first location and flow streamwise substantially parallel to the stream of droplets to entrain the droplets.
Fig. 3a of Mestrom teaches a droplet accelerator 203a where a droplet of fuel 206 having been ejected by the nozzle 202 is introduced into a tube 230 through which a gas flows through openings 231 a-f (see col. 6, lines 17-37). Mestrom teaches the speed of flow of gas through the tube may vary along the length of the tube (see col. 6, lines 35-37). Therefore, an initial flow of gas from opening 231a can impart a first acceleration to the droplet, and a successive opening 231b downstream of the opening 231a can provide a gas flow of higher speed to further accelerate the droplet. Alternatively, Fig. 3b of Mestrom depicts a tapered tube 330 that causes the speed of flow to the gas to increase as it travels along the tapered tube 330 to accelerate the droplet (see col. 7, lines 22-32). Mestrom teaches the gas is used to advantageously provide a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently (see col. 8, lines 1-26).
Mestrom modifies Iwamoto by suggesting a droplet accelerator to impart an acceleration to the droplets at differing speeds along the tube.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom.
Regarding claim 2, Iwamoto discloses the streamwise length of the droplet coalescence zone is between 10 mm and 200 mm (the length of the gas lock may be 4 mm or more, see col. 9, lines 34-41).
Regarding claim 3, while the combination of Iwamoto and Mestrom is silent on the length of the gas acceleration zone being between 20 mm and 200 mm, Mestrom teaches the gas acceleration zone is used to accelerate the fuel droplets to a speed significantly higher than 50 m/s (see col. 6, lines 35-42). Mestrom further teaches the gas is used to advantageously provide a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently (see col. 8, lines 1-26).
In view of such teaching, it would have been obvious to one having ordinary skill in the art at the time the invention was made to modify the length of the gas acceleration zone so there is sufficient distance to accelerate the droplets to a speed where the momentum of the droplet is able to reduce the shockwave effects from previous droplets to ensure optimal placement of the droplet to be vaporized, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. In re Boesch, 617 F.2d 272, 205 USPQ 215 (CCPA 1980). (see MPEP 2144.05 (II)(B))
Regarding claim 4, Iwamoto fails to disclose the gas acceleration zone has a round cross section having a cross sectional area that decreases between the first location and the second location.
Fig. 3b of Mestrom teaches the tube 330 is tapered to cause the speed of flow of gas to increase as it travels along the tapered tube 330 (see col. 7, lines 9-32).
Mestrom modifies Iwamoto by suggesting the gas acceleration zone is tapered from a first location to the second location.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom.
Regarding claim 5, Iwamoto fails to disclose the gas acceleration zone has a circular cross section having a radius that decreases between the first location and the second location.
Fig. 3b of Mestrom teaches the tube 330 is tapered to cause the speed of flow of gas to increase as it travels along the tapered tube 330 (see col. 7, lines 9-32).
Mestrom modifies Iwamoto by suggesting the gas acceleration zone is tapered from a first location to the second location.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom.
Regarding claim 6, the combination of Iwamoto and Mestrom discloses the gas acceleration zone is configured so that a streamwise velocity of the gas does not exceed the speed of sound for the gas (significantly higher than 50 m/s, see Mestrom col. 6, lines 38-42).
Regarding claim 7, the combination of Iwamoto and Mestrom discloses the gas acceleration zone is configured so that a streamwise velocity of the gas at the second location is approximately the speed of sound for the gas at the operating temperature and pressure of the gas (gas speed is significantly more than 50 m/s, see col. 6, lines 38-42).
Regarding claim 8, Iwamoto fails to disclose the streamwise velocity of the gas at the first location is approximately equal to a streamwise velocity of the coalesced droplets leaving the droplet coalescence zone at the first location.
Fig. 3 of Mestrom discloses the droplets of fuel are ejected from the nozzle with a speed of around 50 m/s until the gas accelerates the fuel droplets in the gas acceleration zone (see col. 6, lines 38-42).
Mestrom modifies Iwamoto by suggesting the droplets have a similar speed after the droplet coalescence zone at the first location.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by providing droplets with a known speed prior to the gas acceleration zone for the purpose of ensuring the placement of the droplet at the plasma generation zone for vaporization more consistently and efficiently as taught by Mestrom.
Regarding claim 9, Iwamoto fails to disclose the gas acceleration zone is configured so that the gas accelerates the coalesced droplets such that the coalesced droplets entering the gas acceleration zone at the first location accelerate from about 80 m/s to about 130 m/s while traversing the gas acceleration zone to the second location.
Mestrom teaches the flow of gas through the tube 230 accelerates the droplets to significantly higher than 50 m/s (see col. 6, lines 38-42). Mestrom teaches the gas is used to advantageously provide a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently (see col. 8, lines 1-26).
Mestrom modifies Iwamoto by suggesting accelerating the droplets with a gas.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom. Furthermore, it would have been obvious to one having ordinary skill in the art at the time the invention was made to modify the speed of the accelerated droplets where the momentum of the droplet is able to reduce the shockwave effects from previous droplets to ensure optimal placement of the droplet to be vaporized, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. In re Boesch, 617 F.2d 272, 205 USPQ 215 (CCPA 1980). (see MPEP 2144.05 (II)(B))
Regarding claim 10, Iwamoto discloses a thermalizing structure arranged to be in thermal contact with the gas (buffer space 430 (where gas is introduced) may be heated from the heater 261 provided for the tank 61, see Fig. 7A and col. 14, lines 43-48).
While Iwamoto does not explicitly disclose thermalizing the gas to attain thermal equilibrium with the droplet generator before the gas is introduced into the gas acceleration zone, it should be noted that it has been held that the recitation that an element is “adapted to” perform a function is not a positive limitation but only requires the ability to so perform. It does not constitute a limitation in any patentable sense. In re Hutchinson, 69 USPQ 138.
Regarding claim 11, the combination of Iwamoto and Mestrom does not explicitly disclose the temperature of the thermalizing structure to heat the gas to a temperature between 200 and 300 degrees Celsius.
Mestrom teaches the tube 230 is heated by one or more heaters (not shown) to condition the flow of gas within the tube to enhance the acceleration of the fuel droplets by the heated gas (see cols. 6-7, lines 59-3).
It would have been obvious to one having ordinary skill in the art at the time the invention was made to increase the temperature of the gas to further enhance the acceleration of the fuel droplets as taught by Mestrom, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. In re Boesch, 617 F.2d 272, 205 USPQ 215 (CCPA 1980). (see MPEP 2144.05 (II)(B)). Furthermore, it should be noted that it has been held that the recitation that an element is “adapted to” perform a function is not a positive limitation but only requires the ability to so perform. It does not constitute a limitation in any patentable sense. In re Hutchinson, 69 USPQ 138.
Regarding claim 12, Iwamoto discloses the droplet generator further comprises a source material heater arranged to supply heat to the source material in the droplet generator and the thermalizing structure is arrange to transfer heat between the source material heater and the gas (buffer space 430 (where gas is introduced) may be heated from the heater 261 provided for the tank 61 holding the liquid target material, see Fig. 7A and col. 14, lines 43-48).
Regarding claim 13, Iwamoto discloses the gas is a gas having a low EUV absorption (lock gas including hydrogen, see col. 9, lines 43-46. Paragraph [0019] of the instant application admits that hydrogen has a material property of having a low EUV absorption. Therefore the absorption rate of hydrogen is inherent).
Regarding claim 14, Iwamoto discloses the gas comprises hydrogen (lock gas including hydrogen, see col. 9, lines 43-46).
Regarding claim 15, Iwamoto discloses the shroud comprises molybdenum (damper member 901 situated in the buffer space 430 is made of molybdenum, see Fig. 9 and col. 14, lines 43-54).
While Iwamoto is silent on the disclosed elements as being a refractory metal, the instant application specifically exemplifies a refractory metal to be at least one of molybdenum, tungsten, and tantalum (see paragraph [0019] of the instant application). In light of the applicant’s specification, the listed elements must inherently possess the properties of being a refractory metal.
Regarding claim 16, Iwamoto discloses the shroud comprises molybdenum (damper member 901 situated in the buffer space 430 is made of molybdenum, see Fig. 9 and col. 14, lines 43-54).
Regarding claim 18, Iwamoto fails to disclose a flow management element positioned downstream of the second location and adapted to manage high velocity gas exiting the gas acceleration zone.
Mestrom teaches a droplet accelerator 203a where a droplet of fuel 206 having been ejected by the nozzle 202 is introduced into a tube 230 through which a gas flows through openings 231 a-f (see col. 6, lines 17-37). Mestrom teaches the speed of flow of gas through the tube may vary along the length of the tube (see col. 6, lines 35-37). Therefore, an initial flow of gas from opening 231a can impart a first acceleration to the droplet, and a successive opening 231b downstream of the opening 231a can provide a gas flow of higher speed to further accelerate the droplet. Alternatively, Fig. 3b of Mestrom depicts a tapered tube 330 that causes the speed of flow to the gas to increase as it travels along the tapered tube 330 to accelerate the droplet (see col. 7, lines 22-32). Mestrom teaches the gas is used to advantageously provide a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently (see col. 8, lines 1-26).
Mestrom modifies Iwamoto by suggesting a droplet accelerator to impart an acceleration to the droplets at differing speeds along the tube.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom.
Furthermore, it should be noted that it has been held that the recitation that an element is “adapted to” perform a function is not a positive limitation but only requires the ability to so perform. It does not constitute a limitation in any patentable sense. In re Hutchinson, 69 USPQ 138.
Regarding claim 19, Iwamoto discloses a method of EUV source material generated by a droplet generator (target producing apparatus 275 includes droplet supply device 260, see Fig. 2 and col. 6, lines 28-37; droplets 27 generates plasma from laser light pulse 33 to generate EUV light, see Fig. 2 and col. 5, lines 43-50), the method comprising:
introducing a flow of gas into the droplet generator (gas lock cover 410 has a buffer space 430 connected to a channel 404 for a lock gas, see Fig. 7A and col. 12, lines 7-12);
emitting a stream of liquid EUV source material from a nozzle outlet of a droplet generator (droplet supply device 260 stores liquid droplet material 260 in a tank 61, see Fig. 2 and col. 4, lines 50-57; target controller 51 sets a frequency to produce a jet 277 of the droplet material from the projection 265 at a predetermined speed, see col. 7, lines 4-15; droplets of liquid target used to form a plasma for EUV generation, see col. 5, lines 43-50);
protecting the stream of liquid EUV source material from the flow of gas as the stream of liquid EUV source material transforms into a stream of coalesced droplets using a shroud defining a droplet coalescence zone, extending downstream from the nozzle outlet to a first location (zone below the nozzle 660, surrounded by the gas lock 410, protects the target material along the droplet trajectory 272 from the gas of the gas lock 410 introduced to the droplets from the gas outlets 702, see Fig. 7A);
entraining the coalesced droplets in the flow of gas (gas from the gas lock cover 410 reduces fluctuation in droplet trajectory (e.g. gas entrains the droplet), see Fig. 7A and col. 13, lines 22-30).
Iwamoto fails to teach a method of accelerating droplets of EUV source material by introducing the stream of coalesced droplets into a structure defining a gas acceleration zone extending downstream from a first location, whereby accelerating the flow of gas in the gas acceleration zone as the gas approaches the second location by increasing a velocity of the gas.
Fig. 3a of Mestrom teaches a droplet accelerator 203a where a droplet of fuel 206 having been ejected by the nozzle 202 is introduced into a tube 230 through which a gas flows through openings 231 a-f (see col. 6, lines 17-37). Mestrom teaches the speed of flow of gas through the tube may vary along the length of the tube (see col. 6, lines 35-37). Therefore, an initial flow of gas from opening 231a can impart a first acceleration to the droplet, and a successive opening 231b downstream of the opening 231a can provide a gas flow of higher speed to further accelerate the droplet. Alternatively, Fig. 3b of Mestrom depicts a tapered tube 330 that causes the speed of flow to the gas to increase as it travels along the tapered tube 330 to accelerate the droplet (see col. 7, lines 22-32). Mestrom teaches the gas is used to advantageously provide a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently (see col. 8, lines 1-26).
Mestrom modifies Iwamoto by suggesting providing a pipe 172 having a plurality of openings as taught by Mestrom to introduce gas at differing speeds along the tube.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom.
Regarding claim 20, Iwamoto discloses the streamwise length of the droplet coalescence zone is between 10 mm and 200 mm (the length of the gas lock may be 4 mm or more, see col. 9, lines 34-41).
Regarding claim 21, while the combination of Iwamoto and Mestrom is silent on the length of the gas acceleration zone being between 20 mm and 200 mm, Mestrom teaches the gas acceleration zone is used to accelerate the fuel droplets to a speed significantly higher than 50 m/s (see col. 6, lines 35-42). Mestrom further teaches the gas is used to advantageously provide a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently (see col. 8, lines 1-26).
In view of such teaching, it would have been obvious to one having ordinary skill in the art at the time the invention was made to modify the length of the gas acceleration zone so there is sufficient distance to accelerate the droplets to a speed where the momentum of the droplet is able to reduce the shockwave effects from previous droplets to ensure optimal placement of the droplet to be vaporized, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. In re Boesch, 617 F.2d 272, 205 USPQ 215 (CCPA 1980). (see MPEP 2144.05 (II)(B))
Regarding claim 22, Iwamoto fails to disclose the gas acceleration zone has a round cross section having a cross sectional area that decreases between the first location and the second location.
Fig. 3b of Mestrom teaches the tube 330 is tapered to cause the speed of flow of gas to increase as it travels along the tapered tube 330 (see col. 7, lines 9-32).
Mestrom modifies Iwamoto by suggesting the gas acceleration zone is tapered from a first location to the second location.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom.
Regarding claim 23, Iwamoto fails to disclose the gas acceleration zone has a circular cross section having a radius that decreases between the first location and the second location.
Fig. 3b of Mestrom teaches the tube 330 is tapered to cause the speed of flow of gas to increase as it travels along the tapered tube 330 (see col. 7, lines 9-32).
Mestrom modifies Iwamoto by suggesting the gas acceleration zone is tapered from a first location to the second location.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom.
Regarding claim 24, the combination of Iwamoto and Mestrom discloses the gas acceleration zone is configured so that a streamwise velocity of the gas does not exceed the speed of sound for the gas (significantly higher than 50 m/s, see Mestrom col. 6, lines 38-42).
Regarding claim 25, the combination of Iwamoto and Mestrom discloses the gas acceleration zone is configured so that a streamwise velocity of the gas at the second location is approximately the speed of sound for the gas at the operating temperature and pressure of the gas (gas speed is significantly more than 50 m/s, see col. 6, lines 38-42).
Regarding claim 26, Iwamoto fails to disclose the streamwise velocity of the gas at the first location is approximately equal to a streamwise velocity of the coalesced droplets leaving the droplet coalescence zone at the first location.
Fig. 3 of Mestrom discloses the droplets of fuel are ejected from the nozzle with a speed of around 50 m/s until the gas accelerates the fuel droplets in the gas acceleration zone (see col. 6, lines 38-42).
Mestrom modifies Iwamoto by suggesting the droplets have a similar speed after the droplet coalescence zone at the first location.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by providing droplets with a known speed prior to the gas acceleration zone for the purpose of ensuring the placement of the droplet at the plasma generation zone for vaporization more consistently and efficiently as taught by Mestrom.
Regarding claim 27, Iwamoto fails to disclose the gas acceleration zone is configured so that the gas accelerates the coalesced droplets such that the coalesced droplets entering the gas acceleration zone at the first location accelerate from about 80 m/s to about 130 m/s while traversing the gas acceleration zone to the second location.
Mestrom teaches the flow of gas through the tube 230 accelerates the droplets to significantly higher than 50 m/s (see col. 6, lines 38-42). Mestrom teaches the gas is used to advantageously provide a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently (see col. 8, lines 1-26).
Mestrom modifies Iwamoto by suggesting accelerating the droplets with a gas.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom. Furthermore, it would have been obvious to one having ordinary skill in the art at the time the invention was made to modify the speed of the accelerated droplets where the momentum of the droplet is able to reduce the shockwave effects from previous droplets to ensure optimal placement of the droplet to be vaporized, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. In re Boesch, 617 F.2d 272, 205 USPQ 215 (CCPA 1980). (see MPEP 2144.05 (II)(B))
Regarding claim 28, Iwamoto discloses a thermalizing structure arranged to be in thermal contact with the gas (buffer space 430 (where gas is introduced) may be heated from the heater 261 provided for the tank 61, see Fig. 7A and col. 14, lines 43-48).
Regarding claim 29, the combination of Iwamoto and Mestrom does not explicitly disclose the temperature of the thermalizing structure to heat the gas to a temperature between 200 and 300 degrees Celsius.
Mestrom teaches the tube 230 is heated by one or more heaters (not shown) to condition the flow of gas within the tube to enhance the acceleration of the fuel droplets by the heated gas (see cols. 6-7, lines 59-3).
It would have been obvious to one having ordinary skill in the art at the time the invention was made to increase the temperature of the gas to further enhance the acceleration of the fuel droplets as taught by Mestrom, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. In re Boesch, 617 F.2d 272, 205 USPQ 215 (CCPA 1980). (see MPEP 2144.05 (II)(B)). Furthermore, it should be noted that it has been held that the recitation that an element is “adapted to” perform a function is not a positive limitation but only requires the ability to so perform. It does not constitute a limitation in any patentable sense. In re Hutchinson, 69 USPQ 138.
Regarding claim 30, Iwamoto discloses the droplet generator further comprises a source material heater arranged to supply heat to the source material in the droplet generator and the thermalizing structure is arrange to transfer heat between the source material heater and the gas (buffer space 430 (where gas is introduced) may be heated from the heater 261 provided for the tank 61 holding the liquid target material, see Fig. 7A and col. 14, lines 43-48).
Regarding claim 31, Iwamoto discloses the gas is a gas having a low EUV absorption (lock gas including hydrogen, see col. 9, lines 43-46. Paragraph [0019] of the instant application admits that hydrogen has a material property of having a low EUV absorption. Therefore the absorption rate of hydrogen is inherent).
Regarding claim 32, Iwamoto discloses the gas comprises hydrogen (lock gas including hydrogen, see col. 9, lines 43-46).
Regarding claim 33, Iwamoto discloses the shroud comprises molybdenum (damper member 901 situated in the buffer space 430 is made of molybdenum, see Fig. 9 and col. 14, lines 43-54).
While Iwamoto is silent on the disclosed elements as being a refractory metal, the instant application specifically exemplifies a refractory metal to be at least one of molybdenum, tungsten, and tantalum (see paragraph [0019] of the instant application). In light of the applicant’s specification, the listed elements must inherently possess the properties of being a refractory metal.
Regarding claim 34, Iwamoto discloses the shroud comprises molybdenum (damper member 901 situated in the buffer space 430 is made of molybdenum, see Fig. 9 and col. 14, lines 43-54).
Regarding claim 36, Iwamoto discloses a droplet generator for generating a stream of droplets of EUV source material (target producing apparatus 275 includes droplet supply device 260, see Fig. 2 and col. 6, lines 28-37; droplets 27 generates plasma from laser light pulse 33 to generate EUV light, see Fig. 2 and col. 5, lines 43-50), the droplet generator comprising:
a nozzle adapted to emit liquid EUV source material from a nozzle outlet (droplet supply device 260 stores liquid droplet material 260 in a tank 61, see Fig. 2 and col. 4, lines 50-57; target controller 51 sets a frequency to produce a jet 277 of the droplet material from the projection 265 at a predetermined speed, see col. 7, lines 4-15; droplets of liquid target used to form a plasma for EUV generation, see col. 5, lines 43-50);
at least one inlet adapted to be connected to a source of gas and arranged to introduce a flow of the gas into the droplet generator (gas lock cover 410 has a buffer space 430 connected to a channel 404 for a lock gas, see Fig. 7A and col. 12, lines 7-12);
a shroud defining a first zone, extending downstream from the nozzle outlet to a first location, in which the liquid EUV source material emitted by the nozzle is protected from the flow of the gas by the shroud, the EUV source material being in the form of a stream of droplets at the first location (zone below the nozzle 660, surrounded by the gas lock 410, protects the target material along the droplet trajectory 272 from the gas of the gas lock 410 introduced to the droplets from the gas outlets 702, see Fig. 7A);
Iwamoto fails to disclose a second structure defining a gas acceleration zone, extending downstream from the first location to a second location, in fluid communication with the inlet, arranged to receive the stream of droplets at the first location, and adapted to cause the gas to be introduced into the gas zone downstream of the first location and flow streamwise substantially parallel to the stream of droplets to entrain the droplets.
Fig. 3a of Mestrom teaches a droplet accelerator 203a where a droplet of fuel 206 having been ejected by the nozzle 202 is introduced into a tube 230 through which a gas flows through openings 231 a-f (see col. 6, lines 17-37). Mestrom teaches the speed of flow of gas through the tube may vary along the length of the tube (see col. 6, lines 35-37). Therefore, an initial flow of gas from opening 231a can impart a first acceleration to the droplet, and a successive opening 231b downstream of the opening 231a can provide a gas flow of higher speed to further accelerate the droplet. Alternatively, Fig. 3b of Mestrom depicts a tapered tube 330 that causes the speed of flow to the gas to increase as it travels along the tapered tube 330 to accelerate the droplet (see col. 7, lines 22-32). Mestrom teaches the gas is used to advantageously provide a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently (see col. 8, lines 1-26).
Mestrom modifies Iwamoto by suggesting providing a pipe 172 having a plurality of openings as taught by Mestrom to introduce gas at differing speeds along the tube.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom.
Regarding claim 37, Iwamoto fails to disclose a flow management element positioned downstream of the second location and adapted to manage high velocity gas exiting the gas acceleration zone.
Mestrom teaches a droplet accelerator 203a where a droplet of fuel 206 having been ejected by the nozzle 202 is introduced into a tube 230 through which a gas flows through openings 231 a-f (see col. 6, lines 17-37). Mestrom teaches the speed of flow of gas through the tube may vary along the length of the tube (see col. 6, lines 35-37). Therefore, an initial flow of gas from opening 231a can impart a first acceleration to the droplet, and a successive opening 231b downstream of the opening 231a can provide a gas flow of higher speed to further accelerate the droplet. Alternatively, Fig. 3b of Mestrom depicts a tapered tube 330 that causes the speed of flow to the gas to increase as it travels along the tapered tube 330 to accelerate the droplet (see col. 7, lines 22-32). Mestrom teaches the gas is used to advantageously provide a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently (see col. 8, lines 1-26).
Mestrom modifies Iwamoto by suggesting a droplet accelerator to impart an acceleration to the droplets at differing speeds along the tube.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom.
Furthermore, it should be noted that it has been held that the recitation that an element is “adapted to” perform a function is not a positive limitation but only requires the ability to so perform. It does not constitute a limitation in any patentable sense. In re Hutchinson, 69 USPQ 138.
Regarding claim 38, Iwamoto discloses a method of producing droplets of EUV source material generated by a droplet generator (target producing apparatus 275 includes droplet supply device 260, see Fig. 2 and col. 6, lines 28-37; droplets 27 generates plasma from laser light pulse 33 to generate EUV light, see Fig. 2 and col. 5, lines 43-50), the method comprising:
introducing a flow of gas into the droplet generator (gas lock cover 410 has a buffer space 430 connected to a channel 404 for a lock gas, see Fig. 7A and col. 12, lines 7-12);
emitting liquid EUV source material from a nozzle outlet of the droplet generator (droplet supply device 260 stores liquid droplet material 260 in a tank 61, see Fig. 2 and col. 4, lines 50-57; target controller 51 sets a frequency to produce a jet 277 of the droplet material from the projection 265 at a predetermined speed, see col. 7, lines 4-15; droplets of liquid target used to form a plasma for EUV generation, see col. 5, lines 43-50);
passing the liquid EUV source material through a first zone extending downstream from the nozzle outlet to a first location while protecting the liquid EUV source material from the flow of gas using a shroud, the liquid EUV source material exiting the first zone as a stream of droplets (zone below the nozzle 660, surrounded by the gas lock 410, protects the target material along the droplet trajectory 272 from the gas of the gas lock 410 introduced to the droplets from the gas outlets 702, see Fig. 7A);
introducing the stream of droplets at the first location into a gas zone extending downstream from the first location to a second location (droplets 122 enter a gas introducing member 170 downstream from the nozzle 124 (see paragraph [0169]);
entraining the droplets in the flow of gas (gas from the gas lock cover 410 reduces fluctuation in droplet trajectory (e.g. gas entrains the droplet), see Fig. 7A and col. 13, lines 22-30),
Iwamoto fails to teach a method of accelerating droplets of EUV source material by introducing the stream of coalesced droplets into a structure defining a gas acceleration zone extending downstream from a first location, whereby accelerating the flow of gas in the gas acceleration zone as the gas approaches the second location by increasing a velocity of the gas.
Fig. 3a of Mestrom teaches a droplet accelerator 203a where a droplet of fuel 206 having been ejected by the nozzle 202 is introduced into a tube 230 through which a gas flows through openings 231 a-f (see col. 6, lines 17-37). Mestrom teaches the speed of flow of gas through the tube may vary along the length of the tube (see col. 6, lines 35-37). Therefore, an initial flow of gas from opening 231a can impart a first acceleration to the droplet, and a successive opening 231b downstream of the opening 231a can provide a gas flow of higher speed to further accelerate the droplet. Alternatively, Fig. 3b of Mestrom depicts a tapered tube 330 that causes the speed of flow to the gas to increase as it travels along the tapered tube 330 to accelerate the droplet (see col. 7, lines 22-32). Mestrom teaches the gas is used to advantageously provide a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently (see col. 8, lines 1-26).
Mestrom modifies Iwamoto by suggesting a pipe 172 having a plurality of openings as taught by Mestrom to introduce gas at differing speeds along the tube.
Since both inventions are drawn to droplet generators for EUV source material, it would have been obvious to the ordinary artisan before the effective filing date to modify Iwamoto by modifying the second pipe with the tube as taught by Mestrom for the purpose of providing a higher momentum to the droplet to reduce shockwave effects from previous droplets to ensure optimal placement of the droplet for the droplet to be vaporized more consistently and efficiently as taught by Mestrom.
Claims 17 and 35 are rejected under 35 U.S.C. 103 as being unpatentable over Iwamoto in view of Mestrom and in further view of Meier et al. (US PGPub 2019/0302628, hereinafter Meier).
Regarding claim 17, the combination of Iwamoto and Mestrom fails to disclose the at least one of the first and second structure comprises a boron nitride coating.
Meier teaches providing a covering coating at locations that are prone to damage in (see paragraph [0020]). Meier further teaches specifically teaches coating molybdenum and tantalum with a layer of boron nitride (see paragraph [0021]). Meier discloses that the listed materials (e.g. boron nitride) are advantageously chosen as materials that adheres well to a metal and affords good protection against reactive hydrogen (see paragraph [0021]).
Meier modified the combination of Iwamoto and Mestrom by suggesting a boron nitride coating on the at shroud or second structure which is made of a refractory metal, such as molybdenum.
Since all inventions are drawn to EUV lithography, it would have been obvious to the ordinary artisan before the effective filing date to modify the combination of Iwamoto and Mestrom by providing a boron nitride coating on the at least one of the first and second structure for the purpose of choosing a material that adheres well to a metal and affords good protection against reactive hydrogen as taught by Meier.
Regarding claim 35, the combination of Iwamoto and Mestrom fails to disclose the at least one of the first and second structure comprises a boron nitride coating.
Meier teaches providing a covering coating at locations that are prone to damage in (see paragraph [0020]). Meier further teaches specifically teaches coating molybdenum and tantalum with a layer of boron nitride (see paragraph [0021]). Meier discloses that the listed materials (e.g. boron nitride) are advantageously chosen as materials that adheres well to a metal and affords good protection against reactive hydrogen (see paragraph [0021]).
Meier modified the combination of Iwamoto and Mestrom by suggesting a boron nitride coating on the at least first or second structure which is made of a refractory metal, such as molybdenum or tantalum.
Since all inventions are drawn to EUV lithography, it would have been obvious to the ordinary artisan before the effective filing date to modify the combination of Iwamoto and Mestrom by providing a boron nitride coating on the at least one of the first and second structure for the purpose of choosing a material that adheres well to a metal and affords good protection against reactive hydrogen as taught by Meier.
Conclusion
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to HANWAY CHANG whose telephone number is (571)270-5766. The examiner can normally be reached Monday - Friday 7:30 AM - 4:00 PM EST.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Georgia Epps can be reached on (571) 272-2328. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
Hanway Chang
/HC/ Examiner, Art Unit 2878
/GEORGIA Y EPPS/ Supervisory Patent Examiner, Art Unit 2878