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 .
Specification
The title of the invention is not descriptive. A new title is required that is clearly indicative of the invention to which the claims are directed.
The following title is suggested:
Method for selectively forming a thin film on a semiconductor substrate by injecting a first cleaning gas, a process gas, and a second cleaning gas in a chamber
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1-2, 4, and 8 is/are rejected under 35 U.S.C. 103 as being unpatentable over Korean Patent Appl. Publ. No. KR 10-2018-0011428 to Park, et al. (hereinafter “Park”) in view of U.S. Patent Appl. Publ. No. 2002/0153349 to Okumura, et al. (“Okumura”) and further in view of U.S. Patent Appl. Publ. No. 2003/0045075 to Joo, et al. (“Joo”).
Regarding claim 1, Park teaches a method for selectively forming a thin film on a semiconductor substrate (see the Abstract, Figs. 1-10, and entire reference which teach a method of processing a wafer (W)) comprising:
a preparation process of seating a substrate on a support in a chamber (see Figs. 7-8 and associated descriptive text in pp. 6-10 of the English translation which teach that a wafer (W) is provided on a substrate support (152) in a chamber (151));
a first cleaning process of injecting a first cleaning gas into the chamber and removing a native oxide on the substrate (see Figs. 7-8 and pp. 7-10 which teach using plasma etching to remove an oxide layer from the substrate (W) surface in step (S85) using a mixed fluorine-containing gas such as, for example, CF4 or CHF3);
a growth process of injecting a process gas into the chamber after the first cleaning process and growing a thin film on a growth area on one surface of the substrate (see Figs. 7-8 and pp. 7-10 which teach the growth of an epitaxial Si or SiGe layer onto the substrate (W) using a Si source gas such as silane (SiH4) in step (S89) which is performed after the first cleaning process in step (S85));
a second cleaning process of injecting a second cleaning gas, which is different from the first cleaning gas, into the chamber to remove impurities remaining on the one surface of the substrate (see Figs. 7-8 and pp. 7-10 which teach introducing a second cleaning gas in step (S87) such as Cl2 or CCl4 which is different from the cleaning gas in step (S85) which will necessarily remove impurities remaining on the surface of the wafer (W)); and
a process of generating a plasma in the chamber in the first cleaning process (see Figs. 7-8 and pp. 7-10 which teach the use of plasma etching during the first cleaning process in which the oxide layer is removed in step (S85)),
wherein an inner temperature of the chamber is in a range from 300°C to 750°C (see Figs. 7-8 and pp. 7-10 which teach that the substrate is heated to a temperature of 500 °C or more and 800 °C or less during processing).
Park does not explicitly teach that the plasma is an inductively coupled plasma (ICP). However, in Figs. 1-3 and ¶¶[0082]-[0095] as well as elsewhere throughout the entire reference Okumura teaches an analogous embodiment of a plasma etching system and method which utilizes an induction coil (6) to generate a plasma within a vacuum chamber (1) in order to etch the surface of a substrate (8). In ¶[0093] Okumura specifically teaches the use of an ICP to etch a silicon oxide film on the substrate. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would look to the teachings of Okumura and would recognize that the plasma utilized in the method of Park may be in the form of an ICP since this would involve nothing more than the use of a known method of producing a plasma according to its intended use. Moreover, since the ICP system of Okumura has the advantage of minimizing the formation of spurious deposits within the chamber such as on the dielectric plate, a person of ordinary skill in the art prior to the effective filing date of the invention would be motivated to utilize an ICP in order to improve the etching efficiency and minimize the formation of spurious deposits within the chamber.
Park and Okumura do not teach that the second cleaning process is performed after the growth process. However, in Figs. 5-6 and ¶¶[0024]-[0031] as well as elsewhere throughout the entire reference Joo teaches an analogous method of promoting selective epitaxial growth on a substrate that has predefined regions that are covered and exposed using a mask layer. Epitaxial growth initially proceeds using a Si- or Ge-containing precursor in a second step which is followed by a third step in which Cl2 gas is introduced to remove spurious deposits that may form on the epitaxial growth surface as well as the masked regions. The second and third steps are then repeated until the epitaxial layer is grown to a desired thickness. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would look to the teachings of Joo and would be motivated to repeat the second cleaning process of Park such that it is performed after the growth process in order to remove the formation of spurious deposits until the desired film thickness is reached.
Regarding claim 2, Park teaches that the first cleaning process further comprises a process of removing an impurity produced in the process of removing the native oxide by injecting a second cleaning gas different from the first cleaning gas into the chamber (see Figs. 7-8 and pp. 7-10 which teach introducing a second cleaning gas in step (S87) such as Cl2 or CCl4 which is different from the cleaning gas in step (S85) which will necessarily remove impurities produced during the cleaning process instep (S85)).
Regarding claim 4, Park does not explicitly teach that the second cleaning process comprises a process of generating inductively coupled plasma (ICP) in the chamber. However, as noted supra with respect to the rejection of claim 1, in Figs. 1-3 and ¶¶[0082]-[0095] as well as elsewhere throughout the entire reference Okumura teaches an analogous embodiment of a plasma etching system and method which utilizes an induction coil (6) to generate a plasma within a vacuum chamber (1) in order to etch the surface of a substrate (8). In ¶[0093] Okumura specifically teaches the use of an ICP to etch a silicon oxide film on the substrate. Moreover, the ICP system of Okumura has the advantage of minimizing the formation of spurious deposits within the chamber such as on the dielectric plate. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would look to the teachings of Okumura and would be motivated to utilize an ICP as part of the second cleaning step (S87) in order to improve the etching efficiency and further minimize the formation of spurious deposits within the chamber during the etching process.
Regarding claim 8, Park and Okumura do not teach that the growth process and the second cleaning process are alternately performed a plurality of times. However, in Figs. 5-6 and ¶¶[0024]-[0031] as well as elsewhere throughout the entire reference Joo teaches an analogous method of promoting selective epitaxial growth on a substrate that has predefined regions that are covered and exposed using a mask layer. Epitaxial growth initially proceeds using a Si- or Ge-containing precursor in a second step which is followed by a third step in which Cl2 gas is introduced to remove spurious deposits that may form on the epitaxial growth surface as well as the masked regions. The second and third steps are then repeated until the epitaxial layer is grown to a desired thickness. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would look to the teachings of Joo and would be motivated to alternatively perform the growth and second cleaning process of Park a plurality of times in order to periodically remove the formation of spurious deposits until the desired film thickness is reached.
Claims 5-7 is/are rejected under 35 U.S.C. 103 as being unpatentable over Park in view of Okumura and further in view of Joo and still further in view of U.S. Patent No. 5,356,478 to Chen, et al. (“Chen”).
Regarding claim 5, Park, Okumura, and Joo do not teach a chamber cleaning process that is performed in at least one of before the substrate is loaded into the chamber and after the substrate in the chamber is withdrawn to the outside, wherein the chamber cleaning process comprises a process of injecting the second cleaning gas into the chamber. However, in col. 1, ll. 23-51 Chen teaches that conventional processing of semiconductor wafers leads to a build-up in residue on surfaces inside the plasma treatment chamber which deteriorates the performance of subsequent processes and leads to potential cross-contamination issues. In col. 3, l. 42 to col. 2, l. 60 as well as the Example at col. 4, l. 65 to col. 5, l. 45 Chen specifically teaches that residual contaminants may be efficiently removed from interior surfaces of a plasma treatment chamber using a plasma formed from chlorine (Cl2) and oxygen (O2) gases. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would be motivated to perform a plasma cleaning process before or after the substrate is loaded into the chamber using the same Cl2 gas that was used in the second cleaning process of Park in order to remove residue that builds up on interior surfaces of the chamber and have that same residue removed through the exhaust without being redeposited onto a device wafer.
Regarding claim 6, Park and Chen do not teach that the chamber cleaning process comprises a process of generating inductively coupled plasma (ICP) in the chamber. However, as noted supra with respect to the rejection of claim 1, in Figs. 1-3 and ¶¶[0082]-[0095] as well as elsewhere throughout the entire reference Okumura teaches an analogous embodiment of a plasma etching system and method which utilizes an induction coil (6) to generate a plasma within a vacuum chamber (1) in order to etch the surface of a substrate (8) which also necessarily etches interior surfaces of the chamber itself. In ¶[0007], ¶[0019], and ¶[0086] Okumura specifically teaches the use of an ICP with Cl2 as a process gas to effectively etch various different metals such as iridium. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would look to the teachings of Okumura and would recognize that the plasma utilized for chamber cleaning in the method of Chen may be in the form of an ICP since this would involve nothing more than the use of a known method of producing a plasma according to its intended use. Moreover, the ICP system of Okumura has the advantage of minimizing the formation of spurious deposits which re-deposit on chamber walls. Consequently, a person of ordinary skill in the art prior to the effective filing date of the invention would be motivated to utilize an ICP in order to improve the etching efficiency and minimize the formation of spurious deposits which re-deposit on chamber walls.
Regarding claim 7, Park teaches applying power to a plasma generation unit outside the chamber in order to generate the plasma in the chamber (see Fig. 8 and pp. 8-10 which teach the use of voltage sources (215a) and (215b) to apply power to generate a plasma (P) within the chamber), but does not teach that the RF power used to generate the inductively coupled plasma (ICP) in the chamber cleaning process is different from that of a RF power applied in the first and second cleaning processes. However, in at least ¶¶[0007]-[0008], ¶[0014], ¶[0060], and ¶¶[0082]-[0087] as well as elsewhere throughout the entire reference Okumura teaches the use of an ICP to produce a plasma and etch the surface of the substrate (8) as well interior walls of the chamber (1). A power supply (4) is used to apply a high-frequency power of between 100 kHz to 100 MHz to a coil (6) while a separate power supply (9) is used to apply power to the substrate electrode (7). A different applied power is used to etch an oxide film such as SiO2 compared to a metallic film such as iridium. Moreover, since process parameters such as the plasma size, ion energies, and plasma density are influenced by the RF power it is considered to be a result-effective variable, i.e., a variable which achieves a recognized result. See, e.g., In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See also MPEP 2144.05(II)(B). It therefore would have been within the capabilities of a person of ordinary skill in the art to utilize routine experimentation to determine the optimal RF power delivered to the ICP during the chamber cleaning process of Chen and the surface etching process of Park in order to more efficiently etch the desired areas within the chamber. Due to the differing locations and sizes of the chamber walls and substrate surface this invariably would involve the use of a different RF power for each etching process.
Response to Arguments
Applicants’ arguments filed March 27, 2026, have been fully considered, but they are moot in view of the new grounds of rejection set forth in this Office Action. Applicants’ amendment to claim 1 necessitated the introduction of Joo to teach the use of a second cleaning process after the growth process.
Applicants’ proposed title has been reviewed, but it remains overly generic and is not directed to the elected invention. A proposed replacement title has been supplied by the Examiner.
Applicants argue against the introduction of Joo by contending that Joo fails to disclose a native oxide film removal process prior to the growth process as required by claim 1. See applicants’ 3/27/2026 reply, p. 5. Applicants’ argument is noted, but is unpersuasive as it amounts to arguing against the references individually. In this case it is Park rather than Joo that is relied upon to teach the first cleaning process of removing a native oxide on the substrate. One cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986).
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
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.
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/KENNETH A BRATLAND JR/Primary Examiner, Art Unit 1714
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