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.
Claims 1, 3-4, 6-7 are rejected under 35 U.S.C. 103 as being obvious over Kuno (US20230146001) in view of Tandou (US8426764).
The applied reference has a common assignee with the instant application. Based upon the earlier effectively filed date of the reference, it constitutes prior art under 35 U.S.C. 102(a)(2).
This rejection under 35 U.S.C. 103 might be overcome by: (1) a showing under 37 CFR 1.130(a) that the subject matter disclosed in the reference was obtained directly or indirectly from the inventor or a joint inventor of this application and is thus not prior art in accordance with 35 U.S.C.102(b)(2)(A); (2) a showing under 37 CFR 1.130(b) of a prior public disclosure under 35 U.S.C. 102(b)(2)(B); or (3) a statement pursuant to 35 U.S.C. 102(b)(2)(C) establishing that, not later than the effective filing date of the claimed invention, the subject matter disclosed and the claimed invention were either owned by the same person or subject to an obligation of assignment to the same person or subject to a joint research agreement. See generally MPEP § 717.02.
Referring to claim 1. Kuno et al (US2023/0146001) discloses “Wafer Placement Table”. See Figs. 1-9 and respective portions of the specification. Kuno further discloses a wafer placement table (10) comprising: a ceramic plate (20) having a wafer placement surface on an upper surface; a cooling plate (30) provided on a lower surface of the ceramic plate; and a refrigerant flow path (32) provided inside the cooling plate (Kuno discloses a cooling structure beneath a ceramic plate with refrigerant channels) (See at least Sect. 0005-0012). Kuno further discloses an annular focus-ring placement surface (25a) provided around the wafer placement surface of the ceramic plate and located at a lower level than the wafer placement surface (See at least Sect. 0029, Fig. 1); wherein the cooling plate is made of a material having a lower thermal conductivity than Al (See at least Sect. 0032), wherein a length between an upper surface of the refrigerant flow path and the wafer placement surface is not constant and varies as being long in one part and short in another part (See at least Sect. 0010, 0046). It should further be noted that Kuno teaches that the ceramic plate, cooling plate, refrigerant flow paths, and a focus-ring region have separately controlled thermal characteristics (See at least Sect. 0012). Kuno doesn’t explicitly disclose wherein a flow-path cross-sectional area of the refrigerant flow path is not constant and varies as being small in one part and large in another part, and wherein an aspect ratio defined as a ratio of a vertical length to a horizontal length of a flow-path cross section of the refrigerant flow path is not constant and varies as being small in one part and large in another part, and wherein the aspect ratio of the flow-path cross section of the refrigerant flow path in the portion corresponding to the focus-ring placement surface is smaller than the aspect ratio of the flow-path cross section of the refrigerant flow path in the portion corresponding to the central area of the wafer placement surface. Tandou et al (herein “Tandou”) discloses a “Plasma Processing Apparatus And Plasma Processing Method”. See Figs. 1-13 and respective portions of the specification. Tandou further discloses constructing refrigerant passages so that the sectional areas increase successively across regions of the refrigerant passage in order to maintain desired heat-transfer characteristics (See at least Col. 6 L. 55 – Col. 7 L. 25). Likewise, Tandou teaches that controlling sectional area stabilizes heat-transfer rate within the refrigerant passage regardless of refrigerant phase conditions (See Summary of Invention). Tandou further teaches that sectional areas may expand continuously or in stages within different regions of the passage to obtain improved thermal properties and reduce temperature differences across the wafer (See at least Col. 9 L. 40 – Col. 10 L. 6). Moreover, Tandou teaches wherein geometry reduces temperature differences (See Col. 11 L. 55 – Col. 12 L. 30). It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the refrigerant passages to have varying cross-sectional areas, spacing, geometric proportions (aspect ratio) as taught by Tandou in order to control heat-transfer rate, reduce temperature gradients, and improve wafer temperature uniformity, this combination would have improved temperature uniformity across the wafer surface and reduced thermal stress within the wafer placement table.
Referring to claim 3. Kuno in view of Tandou disclose the combination as described above. Kuno doesn’t explicitly disclose wherein the length between the upper surface of the refrigerant flow path and the wafer placement surface, the flow-path cross-sectional area of the refrigerant flow path, and the aspect ratio of the flow-path cross section of the refrigerant flow path are designed such than an efficiency of heat exchange in an outer peripheral area of the wafer placement surface is higher than an efficiency of heat exchange in a central area of the wafer placement surface. Kuno discloses separate refrigerant supply to central and outer flow paths so that temperatures of the wafer placement surface and focus-ring placement surface can be independently controlled (See at least Sect. 0012). Tandou teaches controlling heat-transfer rate via passage geometry (See at least Col. 6 L. 55 – Col. 7 L. 25, Col. 9 L. 40 – Col. 10 L. 6, Col. 11 L 55 – Col. 12 L. 30). It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to configure the outer region for higher heat-exchange efficiency to compensate for peripheral thermal loads, which would improve temperature uniformity.
Referring to claim 4. Kuno doesn’t’ disclose wherein, the outer peripheral area of the wafer placement surface, the length between the upper surface of the refrigerant flow path and the wafer placement surface is shorter, the flow-path cross-sectional area of the refrigerant flow path is smaller, and the aspect ratio of the flow-path cross section of the refrigerant flow path is smaller than in the central area of the wafer placement surface. Tandou discloses adjusting passage sectional areas across regions to control heat-transfer characteristics and reduce temperature differences (See at least Col. 6 L. 55 – Col. 7 L. 25, Col. 9 L. 40 – Col. 10 L. 6, Col. 11 L 55 – Col. 12 L. 30). It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the system of Kuno to place higher-efficiency cooling closer to regions requiring greater thermal management (wafer periphery/edges) to improve temperature uniformity and temperature distribution. It should be noted that changing sectional areas inherently modifies geometric proportions.
Referring to claims 6-7. Kuno doesn’t disclose wherein a part of the refrigerant flow path where the aspect ratio is small has an aspect ratio of 0.5 or smaller or large and has an aspect ratio of 1 or greater. Tandou teaches modifying sectional area and geometry of refrigerant passages across multiple regions to regulate heat-transfer rate. Its generally understood that aspect ratio is a geometric parameter directly related to cross-sectional configuration. It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to select particular aspect ratios/geometric proportions as the configuration leads to the ability to optimize cooling performance and selecting particular ratios constitutes routine optimization.
Claims 2, 5, 8 are rejected under 35 U.S.C. 103 as being obvious over Kuno (US20230146001) in view of Tandou (US8426764) and in further view Erickson et al (US12131890).
Referring to claim 2. Kuno in view of Tandou disclose the combination as described above in detail. Kuno doesn’t explicitly disclose wherein the cooling plate has a thermal conductivity of 50 W/mK or lower. Erickson discloses a “Chuck For Plasma Processing Chamber”. See Figs. 1-3 and respective portions of the specification. Erickson further discloses an electrostatic chuck (ESC) (100), a ceramic plate (104), base plate (108) with flow paths/channels (109) and further discloses that the ESC may be formed from aluminum-silicon carbide alloys to provide improved thermal uniformity due to higher thermal conductivity relative to the other material. It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to select a cooling plate material having an appropriate thermal conductivity (50 W/mk or lower) to achieve desired thermal performance, choosing a material with thermal conductivity of 50 W/mk or lower would allow for improved thermal operating range and wafer processing uniformity.
Referring to claim 5. Kuno doesn’t disclose wherein the focus-ring placement surface is designed to receive an annular focus-ring placement surface is designed to receive an annular focus ring whose outside diameter is greater than an outside diameter of the ceramic plate and an outside diameter of the cooling plate. Erickson discloses wherein an edge ring surrounds the electrostatic chuck and teaches controlling gaps and thermal behavior between the edge ring and base plate (See at least Col. 2 L. 53 – Col. 3 L. 5, Col. 4 L. 5-40). It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to incorporate a focus ring with a larger diameter than the wafer support, as the increased dimensions would allow for improved thermal and processing uniformity.
Referring to claim 8. Kuno doesn’t disclose wherein the ceramic plate is made of alumina, and wherein the cooling plate is made of Ti or a Ti alloy. Erickson discloses a ceramic plate comprising aluminum oxide or aluminum nitride bonded to a base plate containing temperature-control channels (See at least Col 2 L. 55 – Col. 3 L. 5). It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention in view of the teachings of Erickson to select alumina for the ceramic plate and a metal base plate material as this pairing would balance thermal conductivity and thermal expansion.
Conclusion
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/TERRELL H MATTHEWS/Primary Examiner, Art Unit 3653