DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim1-3, claim 4, and claim 6 are rejected under 35 U.S.C. 103 as being unpatentable over Tan (US10727073B2) in view of Takahashi et al. (US2016/0225637A1).
As to claim 1, Tan teaches in atomic layer etching 3D structures: Si and SiGe and Ge smoothness on horizontal and vertical surfaces that by both chemisorption and deposition mechanisms in combination with oxide passivation are described herein. Methods involving atomic layer etching using a chemisorption mechanism involve exposing the semiconductor material to chlorine to chemisorb chlorine onto the substrate surface and exposing the modified surface to argon to remove the modified surface. (abstract) Tan additionally teaches that the second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 2). Other generic fluorine source such as nitrogen trifluoride (NF3) and/or carbon fluoride (CFx, CHFx) can be used (line 12, col.6). Etching chemistry is introduced into the chamber in operation 220 of FIG. 1A. The etching chemistry may be referred to herein as etching gas or reactive gas. In some embodiments, etching chemistry may include a halogen-containing gas (line 3, column 8). The second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 5). And an ALE cycle includes a modification operation to form a reactive layer, followed by a removal operation to remove or etch only this modified layer (col 5, line 19).
The teachings of Tan differ from that of the instantly claimed invention in that Tan does not teach explicitly selectively removing silicon-containing material relative to silicon-and-germanium-containing material in the presence of both materials on the same substrate.
Takahashi disclose in etching method and storage medium, that an etching method includes: disposing a target substrate including a silicon and a silicon-germanium within a chamber; and performing both of selectively etching the silicon-germanium with respect to the silicon and selectively etching the silicon with respect to the silicon-germanium by varying ratios of F2 gas and NH3 gas in an etching gas that has a gas system including the F2 gas and the NH3 gas (abstract). Although the etched surface is extremely easily oxidized, the etched surface may be processed using the NH3 gas and the HF gas such that the etched surface is terminated with hydrogen to be prevented from being oxidized (para. 59).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the ALE process of Tan to include the selective etching of silicon relative to silicon-germanium as taught by Takahashi. It would have been prima facie obvious for one of ordinary skill in the art to modify because both references are directed to semiconductor processing of Si/SiGe materials using fluorine-based chemistries. And the motivation of incorporating Takahashi’s selective etching technique into Tan’s ALE framework in order is to improve etch selectivity in Si/SiGe structures. One of ordinary skill in the art would have a reasonable expectation of success due to the fluorine-based etching the silicon with respect to the silicon-germanium chemistries in both references.
As to claim 2, Tan and Takahashi teach as applied in claim 1 above, Tan further teaches that the halogen-containing gas is selected from the group consisting of nitrogen trifluoride, fluorocarbons, and fluorine (col 19, line 42, claim 6). Other generic fluorine source such as nitrogen trifluoride (NF3) and/or carbon fluoride (CFx, CHFx) can be used and sulfur hexafluoride is provided as an example (col 6, line 12). In some embodiments, the reactive gas is flowed with a second reactive gas, such as hydrogen and a halogen-containing gas, such as nitrogen trifluoride, fluorine, and a mixture of nitrogen trifluoride and fluorine. In one example, in some embodiments, ALE-II may be performed by reacting sulfur hexafluoride (SF6) with hydrogen (H2) to deposit a sulfur-containing fluorine-containing chemistry on the surface of the material to be etched. In some embodiments, the sulfur-containing deposition chemistry may include a fluorocarbon such as carbon tetrafluoride (CF4), hexafluoro-2-butyne (C4F6), fluoromethane (CH3F), or other CHFx gases or similar compounds and combinations thereof (line 10, col 10).
Takahashi further teaches that there is known technique of performing the selective etching by using an etching gas including SF6 and CF4 to which a germanium-containing gas is added (para. 4).
As to claim 3, Tan and Takahashi teach as applied in claim 1 above, Tan further teaches that the second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 5).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to use boron trichloride (BCl3) as the chlorine-containing precursor in Tan’s ALE process because Tan discloses boron chloride as suitable halogen-containing reactive gas.
As to claim 4, Tan and Takahashi teach as applied in claim 1 above, Tan further teaches that the reactive gas further comprises a second reactive gas selected from the group consisting of hydrogen and a halogen-containing gas (claim 2). In some embodiments, the reactive gas further includes a second reactive gas such as hydrogen (col 1, line 48).
As to claim 6, Tan and Takahashi teach as applied in claim 1 above, Tan teaches that ALE-I may be performed using a chlorine-containing chemistry during modification by chemisorption operations (operation 220) and an inert gas chemistry such as argon during removal operations (col 7, line 63). In some embodiments, ALE-II may be performed using a sulfur-containing deposition chemistry with a second reactant during modification by deposition operations and an inert gas chemistry such as argon during removal operations. (col 9, line 64)
In this purge operation, non-surface-bound active chlorine species may be removed from the process chamber. This can be done by purging and/or evacuating the process chamber to remove the active species, without removing the adsorbed layer. The species generated in a chlorine plasma can be removed by simply stopping the plasma and allowing the remaining species decay, optionally combined with purging and/or evacuation of the chamber. Purging can be done using any inert gas such as N2, Ar, Ne, He and combinations thereof (col 8, line 62).
Takahashi further disclosed that Ar gas is used as a dilution gas or a purge gas (para. 40).
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Tan (US10727073B2) in view of Takahashi (US 20160225637A1) as applied in claim 4 above, and further in view of Zhu (US20240087910A1).
Tan and Takahashi teach as claim 1 above.
The Teachings of Tan and Takahashi differ from that of the instantly claimed invention is
that Tan and Takahashi didn’t teach that a flow rate ratio of the fluorine-containing precursor relative to the hydrogen-containing precursor is less than or about 20:1.
Zhu teaches in Methods of highly selective silicon oxide removal, that a flow rate ratio of the fluorine-containing precursor relative to the hydrogen-containing precursor is less than or about 10:1 (claim 18). Zhu further teaches that to maintain high selectivity, the flow rate of the fluorine-containing precursor and/or the hydrogen-containing precursor may be provided to maintain the removal rate of the exposed region of silicon-and-oxygen-containing material (para.57).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to maintain a fluorine-to-hydrogen precursor flow rate ratio of less than or about 20:1 in the combined Tan and Takahashi processes in view of Zhu because all three references are directed to fluorine-based semiconductor etching processes. Zhu explicitly teaches that to maintain high selectivity, the flow rate of the fluorine-containing precursor and/or the hydrogen-containing precursor may be provided to maintain the removal rate of the exposed region of silicon-and-oxygen-containing material.
Further, “In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists” (See MPEP 2144.05(I)).
Claim 7-9 are rejected under 35 U.S.C. 103 as being unpatentable over Tan (US10727073B2) in view of Takahashi (US 20160225637A1) as applied to claim 1 above, and further in view of Wang (US20220359214A1).
As to claim 7, Tan and Takahashi teach as applied in claim 1 above.
The Teachings of Tan and Takahashi differ from that of the instantly claimed invention is that Tan and Takahashi didn’t teach explicitly that the processing region is maintained plasma-free.
Wang teaches in metal etch in high aspect-ratio features that the processing region is maintained plasma free while flowing a second fluorine-containing precursor into the processing region of the semiconductor processing chamber (claim 17). Wang further teaches that local plasmas may damage the substrate through the production of electric arcs as they discharge (para. 3). This may advantageously protect a variety of intricate structures and films patterned on the substrate, which may be damaged, dislocated, or otherwise warped if directly contacted by a generated plasma (para. 33). The method may be performed to facilitate control of the profile through the structure, and improve etch characteristics, such as surface smoothness of the metal within the recessed sections of the structure (para. 43).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to maintain the processing region plasma-free in the combined Tan and Takahashi process as taught by Wang because plasma-free ALE will reduce ion induced damage, improve surface smoothness.
As claim 8, Tan and Takahashi teach as applied in claim 1 above.
The Teachings of Tan and Takahashi differ from that of the instantly claimed invention is that Tan and Takahashi didn’t teach explicitly that the processing region is maintained at a temperature of greater than or about 200° C.
Wang teaches as above, Wang further disclosed that a temperature within the processing region is maintained at less than or about 500° C (claim 3). Wang further teaches that at higher temperatures, further dissociation of the fluorine-containing materials may occur, which may produce more fluorine radicals. As the amount of fluorine radicals increases, the protective gas may be incapable of controlling the reaction sufficiently (para.51).
It would have been obvious to one of ordinary skill in the art before the effective filling
date of the claimed invention to maintain the processing region at a temperature greater than or about 200°C in the combined Tan and Takahashi process in view of Wang. Because Wang’s disclosure encompasses operating temperatures above 200°C. A person of ordinary skill in the art would have been motivated to select a temperature within the range taught by Wang to sufficiently control the etching reaction in ALE-type semiconductor processing, with a reasonable expectation of success.
As to claim 9, Tan and Takahashi teach as applied in claim 1 above, Takahashi further teaches that In Experimental Example 1, a blanket wafer having a poly-Si film formed thereon and another blanket wafer having a SiGe film formed thereon were prepared. Using F2 gas and NH3 gas as an etching gas, the poly-Si film and the SiGe film were etched by varying a NH3 gas flow rate. The etching was performed under the following conditions (para. 62) Pressure: 4 Torr/2 Torr (para. 66)
Tan further teaches that stabilizing the chamber may use the same flow rates, pressure, temperatures, and other conditions as the chemistry to be used in the operation following the stabilization (col 8, line 39).
The Teachings of Tan and Takahashi differ from that of the instantly claimed invention is that Tan and Takahashi didn’t teach explicitly that the processing region is maintained at a pressure of greater than or about 1 Torr.
Wang further teaches that Wang teaches that the method of etching of claim 1, wherein the method is performed at a chamber operating pressure of between about 1 Torr and about 50 Torr (Claim 8). By utilizing pressures of greater than or about 1 Torr, delivery of etchants through high aspect-ratio structures may be facilitated (para 52).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to maintain the processing region at a pressure greater than or about 1 Torr in the combined Tan and Takahashi process in view of Wang because chamber pressure is one of the factors which could be used in stabilizing the chamber, and facilitate the operation of delivery of etchants through high aspect-ration structures. A person of ordinary skill in the art would have been motivated to select a pressure within the range taught by Wang to achieve predictable improvements in process stability and etch performance.
Claim 10 is rejected under 35 U.S.C. 103 as being unpatentable over Tan (US10727073B2) in view of Takahashi (US 20160225637A1) as applied to claim 1 above, and further in view of Carns (J. Electrochem. Soc.142, 1260, 1995).
Tan and Takahashi teach as applied in claim 1 above.
The Teachings of Tan and Takahashi differ from that of the instantly claimed invention is that Tan and Takahashi didn’t teach that an etch rate of the silicon-containing material is greater than or about 0.5 Å/minute.
Carns teaches in the Chemical Etching of Si1-xGeX in HF: H2O2: Ch3COOH, that Etch rates on the order of 1100 Å /min were observed for p+ Si0.60Ge0.40 (introduction).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to achieve an etch rate greater than or about 0.5 Å/min in the combined Tan and Takahashi process in view of Carns because Carns establishes that silicon-containing materials and related SiGe systems are readily etchable at rates far exceeding the claimed minimum threshold. A person of ordinary skill in the art would have been motivated to operate within known etch rate with a reasonable expectation of success.
Claim 11-14 and claim 16 are rejected under 35 U.S.C. 103 as being unpatentable over Tan (US10727073B2) in view of Takahashi (US 20160225637A1).
Regards claim 11, Tan teaches in atomic layer etching 3D structures: Si and SiGe and Ge smoothness on horizontal and vertical surfaces that by both chemisorption and deposition mechanisms in combination with oxide passivation are described herein. Methods involving atomic layer etching using a chemisorption mechanism involve exposing the semiconductor material to chlorine to chemisorb chlorine onto the substrate surface and exposing the modified surface to argon to remove the modified surface (abstract). Tan additionally teaches that the second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 2). Other generic fluorine source such as nitrogen trifluoride (NF3) and/or carbon fluoride (CFx, CHFx) can be used (col 6, line 12). Etching chemistry is introduced into the chamber in operation 220 of FIG. 1A. The etching chemistry may be referred to herein as etching gas or reactive gas. In some embodiments, etching chemistry may include a halogen-containing gas (col 8, line 3). The second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 5).
The teachings of Tan differ from what from that of the instantly claimed invention is that Tan does not explicitly teach selectively removing at least a portion of the silicon-containing material from the substrate.
Takahashi teaches in etching method and storage medium, that an etching method includes: disposing a target substrate including a silicon and a silicon-germanium within a chamber; and performing both of selectively etching the silicon-germanium with respect to the silicon and selectively etching the silicon with respect to the silicon-germanium by varying ratios of F2 gas and NH3 gas in an etching gas that has a gas system including the F2 gas and the NH3 gas (abstract).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to achieve the selective silicon removal taught by Takahashi. Both references are directed to semiconductor etching processes involving silicon and silicon-germanium materials and seek to improve etch selectivity between such materials. A person of ordinary skill in the art would have been motivated to incorporate Takahashi's known selective silicon etching techniques into Tan's ALE process in order to improve etch selectivity during processing of Si/SiGe structures, with a reasonable expectation of success because both references employ fluorine-based chemistries in Si and SiGe etching to control material removal.
Regards claim 12, Tan and Takahashi teach as applied in claim 11 above, Tan further teaches that the second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 5).
One of ordinary skill in the art would have recognized that boron chloride (BCl3) is a boron-containing precursor that further comprises a halogen, namely chlorine.
Regards to claim 13, Tan and Takahashi teach as applied in claim 11 above, Tan further teaches that the second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 5).
Boron trichloride (BCl3) is one of the specifically recited boron-containing precursors of claim 13. Therefore, Tan teaches the additional limitation of Claim 13, and the combination of Tan and Takahashi renders the subject matter of Claim 13 obvious.
Regards to claim 14, Tan and Takahashi teach as applied in claim 11 above, Tan further
teaches that the second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 2). Other generic fluorine source such as nitrogen trifluoride (NF3) and/or carbon fluoride (CFx, CHFx) can be used (col.6, line 12). Etching chemistry is introduced into the chamber in operation 220 of FIG. 1A. The etching chemistry may be referred to herein as etching gas or reactive gas. In some embodiments, etching chemistry may include a halogen-containing gas (line 3, column 8). The second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 5).
Tan explicitly teaches that generic fluorine sources may include nitrogen trifluoride (NF₃) and fluorocarbon species (CFx, CHFx) (col. 6, line 12). Nitrogen trifluoride (NF₃) is one of the specifically recited fluorine-containing precursors of Claim 14. Therefore, Tan teaches the additional limitation of Claim 14, and the combination of Tan and Takahashi renders the subject matter of Claim 14 obvious.
Regards claim 16, Tan and Takahashi teach as applied in claim 11 above, Tan further teaches that Tan teaches that the reactive gas further comprises a second reactive gas selected from the group consisting of hydrogen and a halogen-containing gas (claim 2). The oxygen-containing plasma is generated by introducing an oxygen-containing gas selected from the group consisting of oxygen, carbon dioxide, and sulfur dioxide; and igniting a plasma (claim 16). Tan additionally teaches that in some embodiments, another reactant gas, such as oxygen, is used during operation 220 to remove a modified layer (col 8, line 56).
It would have been obvious to one of ordinary skill in the art at the time the invention was made to employ O₂ as the oxygen-containing precursor in the combined Tan and Takahashi process because Tan expressly identifies O₂ as a suitable oxygen source and used during operation to remove a modified layer.
Claim 15 is rejected under 35 U.S.C. 103 as being unpatentable over Tan (US10727073B2) in view of Takahashi (US 20160225637A1) as applied in claim 11 above, and further in view of Korolik (US9449843B1).
Tan and Takahashi teach as applied in claim 11 above.
The Teachings of Tan and Takahashi differ from that of the instantly claimed invention is that Tan and Takahashi didn’t teach explicitly that the semiconductor processing method of claim 11, further comprising: providing an oxygen-containing precursor to the processing region with the fluorine-containing precursor.
Korolik teaches that a method of etching a metal layer, the method comprising: placing a patterned substrate into a substrate processing region of a substrate processing chamber, wherein the patterned substrate comprises an exposed portion of the metal layer, wherein the metal layer comprises a first metal element; and flowing an oxygen-containing precursor into the substrate processing region; oxidizing the exposed portion of the metal layer, wherein oxidizing the exposed portion forms an oxidized portion of the metal layer and leaves behind an unoxidized portion of the metal layer; and flowing a metal-and-halogen-containing precursor into the substrate processing region; selectively etching the oxidized portion of the metal layer, wherein the metal-and-halogen-containing precursor comprises a second metal element and a halogen (claim 1). The operation of removing the oxidized portion of the metal-containing layer etches the oxidized portion of the metal-containing layer at over one hundred times as fast as the operation etches the unoxidized portion (claim 5). Operations i) and ii) are repeated N times to remove a thickness of (N+1) times the cycle thickness (claim 6).
Korolik additional teaches that other sources of oxygen may be used to augment or replace the O.sub.2. In general, an oxygen-containing precursor may be flowed into the substrate processing region in embodiments. The oxygen-containing precursor may include one or more of O, O2, O3, H2O, N2O, NO2, NO, H2O2, an organic peroxide, and SO3 in embodiments. The exposed portion of tungsten is oxidized (operation 130) by exposure to the oxygen-containing precursor to form a layer of tungsten oxide. Operation 130 may proceed to a certain thickness after which further exposure does not increase the thickness of the tungsten oxide layer. This trait lends itself to forming a uniform oxidation layer (in this case a uniform tungsten oxide layer). The oxygen-containing precursor or patterned substrate temperature may be selected to adjust the thickness of the tungsten oxide layer (col 4, line 11).
korolik further teaches that the etch removes material in a conformal manner by including an oxidation operation to form a thin uniform metal oxide which is then removed by exposing the metal oxide to a metal-halogen precursor in a substrate processing region (summary 4) The methods involve a conformal oxidation operation preceding exposure to a metal-nitride precursor which removes only the evenly oxidized portion of the metal or metal nitride (summary 30).
It would have been obvious to one of ordinary skill in the art before the effective filling
date of the claimed invention to modify the etching process of Takahashi to include the oxygen-containing precursor taught by Korolik because both references are directed to selective semiconductor etching processes employing halogen-based chemistries to achieve controlled material removal. A person of ordinary skill in the art would have recognized that introducing oxygen-containing species as taught by Korolik augment oxygen, to adjust thickness and forming a uniform oxidation layer during the selective etching of silicon relative to silicon-germanium. Such modification of oxidation-assisted etching techniques to improve the performance of Takahashi's selective etching process.
Claim 17 rejected under 35 U.S.C. 103 as being unpatentable over Tan (US10727073B2) in view of Takahashi (US 20160225637A1) as applied in claim 11 above, and further in view of Wang (US20220359214A1).
Tan and Takahashi teach as applied in claim 11 above.
The Teachings of Tan and Takahashi differ from that of the instantly claimed invention is that Tan and Takahashi didn’t teach explicitly that the processing region is maintained at a temperature of greater than or about 400° C.; and the processing region is maintained at a pressure of greater than or about 3 Torr.
Wang teaches as claim 7-9 above, Wang further teaches that method of etching comprising: flowing a first fluorine-containing precursor and a secondary gas into a processing region of a semiconductor processing chamber; contacting a substrate with the first fluorine-containing precursor and the secondary gas, wherein the substrate defines a memory hole in a 3D NAND structure, wherein the high-aspect ratio is characterized by an aspect ratio of greater than or about 10:1, and wherein the substrate comprises an exposed metal extending laterally into recesses formed perpendicular to a depth of the memory hole; etching the exposed metal within the memory hole; forming a plasma of an oxygen-containing precursor; contacting the exposed metal with plasma effluents of the oxygen-containing precursor to produce oxidized metal; flowing a second fluorine-containing precursor into the processing region of the semiconductor processing chamber; and removing the oxidized metal, wherein a temperature within the semiconductor processing chamber is maintained between about 200° C. and about 500° C (claim 11). Process conditions may also impact the operations performed in method 400. Each of the operations of method 400 may be performed during a constant temperature in embodiments, while in some embodiments the temperature may be adjusted during different operations (para. 51). The method of etching of claim 11, wherein a pressure within the semiconductor processing chamber is maintained between about 1 Torr and about 50 Torr. (canceled claim 15). Wang further teaches that in some embodiments, the process may occur at a variety of pressures, which may facilitate operations in any of a number of process chambers. By utilizing pressures of greater than or about 1 Torr, delivery of etchants through high aspect-ratio structures may be facilitated (para. 52).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to operate the Tan and Takahashi etching process under the temperature and pressure conditions taught by Wang because process conditions may also impact the operations performed. And pressure may facilitate operations in any of a number of process chambers. By utilizing pressures of greater than or about 1 Torr, delivery of etchants through high aspect-ratio structures may be facilitated. A person of ordinary skill in the art would have been motivated to optimize process conditions, including temperature and pressure, within known workable ranges such as those disclosed by Wang in order to achieve desired etching performance with a reasonable expectation of success.
Claim 18 and claim 19 are rejected under 35 U.S.C. 103 as being unpatentable over Tan (US10727073B2) in view of Korolik (US9449843B1).
Regards to claim 18, Tan teaches in atomic layer etching 3D structures: Si and SiGe and Ge smoothness on horizontal and vertical surfaces that by both chemisorption and deposition mechanisms in combination with oxide passivation are described herein. Methods involving atomic layer etching using a chemisorption mechanism involve exposing the semiconductor material to chlorine to chemisorb chlorine onto the substrate surface and exposing the modified surface to argon to remove the modified surface (abstract). Tan additionally teaches that the second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 2). Other generic fluorine source such as nitrogen trifluoride (NF3) and/or carbon fluoride (CFx, CHFx) can be used (line 12, col.6). Etching chemistry is introduced into the chamber in operation 220 of FIG. 1A. The etching chemistry may be referred to herein as etching gas or reactive gas. In some embodiments, etching chemistry may include a halogen-containing gas (line 3, column 8). The second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 5). Introducing an oxygen-containing gas selected from the group consisting of oxygen, carbon dioxide, and sulfur dioxide (claim 16).
The teachings of Tan differ from that of the instantly claimed invention is that Tan didn’t teach explicitly oxidizing a surface layer with an oxygen-containing precursor and subsequently selectively removing the oxidized layer using a halogen-containing precursor.
Korolik teaches flowing an oxygen-containing precursor into the substrate processing region; oxidizing the exposed portion of the metal layer, wherein oxidizing the exposed portion forms an oxidized portion of the metal layer and leaves behind an unoxidized portion of the metal layer; and flowing a metal-and-halogen-containing precursor into the substrate processing region; selectively etching the oxidized portion of the metal layer, wherein the metal-and-halogen-containing precursor comprises a second metal element and a halogen (claim 1). And the oxygen-containing precursor comprises one of O, O2, O3, N2O, NO2, NO or SO3 (claim 10). The halogen comprises one of Cl, F, Br or I (claim 14). The operation of removing the oxidized portion of the metal-containing layer etches the oxidized portion of the metal-containing layer at over one hundred times as fast as the operation etches the unoxidized portion (claim 5).
removing a cycle thickness of the metal-containing layer with a processing cycle of:
i) flowing an oxygen-containing precursor into the substrate processing region, oxidizing the exposed portion of the metal-containing layer, wherein oxidizing the exposed portion creates an oxidized portion of the metal-containing layer but leaves behind an unoxidized portion of the metal-containing layer; and
ii) flowing a metal-and-halogen-containing precursor into the substrate processing region, removing the oxidized portion of the metal-containing layer and leaving the remaining portion of the metal-containing layer intact, wherein the metal-and-halogen-containing precursor comprises a second metal element and a halogen (claim 4).
It would have been obvious to one of ordinary skill before the effective filling date of the claimed invention to modify the etching process of Tan by incorporating the oxidation-assisted selective removal process taught by Korolik. Both references are directed to highly controlled semiconductor etching processes based on sequential surface modification and removal reactions. One of ordinary skill in the art would have been motivated to use Korolik's oxidation-and-removal within Tan's ALE process to improve etch selectivity by conformal oxidation operation preceding exposure to a metal-nitride precursor which removes only the evenly oxidized portion of the metal or metal nitride. Furthermore, because both references utilize oxygen-containing and halogen-containing chemistries to control surface reaction and material removal, a reasonable expectation of success would have existed.
Regards to claim 19, Tan and Korolik teaches as claim 18 above, Tan additionally teaches that the second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 2). Other generic fluorine source such as nitrogen trifluoride (NF3) and/or carbon fluoride (CFx, CHFx) can be used (line 12, col.6). Etching chemistry is introduced into the chamber in operation 220 of FIG. 1A. The etching chemistry may be referred to herein as etching gas or reactive gas. In some embodiments, etching chemistry may include a halogen-containing gas (line 3, column 8). The second reactive gas is a halogen-containing gas selected from the group consisting of chlorine, boron chloride (claim 5). introducing an oxygen-containing gas selected from the group consisting of oxygen, carbon dioxide, and sulfur dioxide (claim 16).
It would have been obvious to one of ordinary skill in the art at the time of the invention to utilize the specifically disclosed BCl3, NF3, and O2 chemistries within the combined Tan and Korolik process because both references teach employing oxygen-containing and halogen-containing chemistries to control surface modification and selective removal reactions. Selection of these disclosed species from among the known reactive gases taught by the references would have been an obvious matter of routine optimization to achieve desired etch selectivity and process control.
Claim 20 is rejected under 35 U.S.C. 103 as being unpatentable over Tan (US10727073B2) in view of Korolik (US9449843B1) as applied in claim 18 above, further in view of Dezela (US20230268187A1).
Tan and Korolik teach as applied in claim 18 above.
The teachings of Tan and Korolik differ from that of the instantly claimed invention is that Tan and Korolik didn’t teach explicitly that the processing region is maintained at a temperature of greater than or about 350° C.
Dezelah teaches in atomic layer etching, that according to some embodiments, ALE cycles may be performed at temperatures ranging from about 20 to about 1200° C., about 50 to about 800° C., about 75 to about 600° C., about 300° C. to about 500° C., or from about 350° C. to about 450° C. In some embodiments, the cycles are carried out at a temperature of about 450° C (para 112). Dezelah additionally teaches that in some embodiments, the etching is continuous etching and can be controlled by various process parameters such as pressure, temperature, exposure times and purge times etc. (para 90).
It would have been obvious to one of ordinary skill in the art at the time of the invention to perform the Tan and Korolik etching process at a temperature greater than or about 350°C as taught by Dezelah because temperature is one of the control factors in etching processes. A person of ordinary skill in the art would have understood that adjusting process temperature, one of the control factors in the atomic layer etching, and would have been motivated to employ the temperature ranges taught by Dezelah to optimize the etching characteristics.
Conclusion
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XIN WEN
Examiner
Art Unit 1713
/X.W./Examiner, Art Unit 1713
/BINH X TRAN/Primary Examiner, Art Unit 1713
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