Ex parte Srivastava
Appeal 2009013335, Appl No. 10/755,617, Tech. Center 1700
November 22, 2010
The claim at issue read:
1. A baffle plate assembly for distributing gas flows into an adjacent process chamber containing a semiconductor wafer to be processed, comprising:
a single generally circular planar gas distribution portion having a plurality of apertures therein;
a flange surrounding the gas distribution portion; and
an apertureless impingement device centrally attached to the gas distribution portion,
wherein the device includes
a generally circular cap and a stem,
the stem being in thermal contact with the gas distribution portion.
The Examiner rejected the claim as being anticipated by Kinnard. On appeal, the Applicant argued a three claim limitations, and distinguished the "thermal contact" limitation as follows:
Further, though the sapphire impingement plate 62 in [Kinnard] does "prevent the radially inward portion of the wafer 22 from overheating", it is essentially floating from a thermal perspective, and hence gets heated up by the hot plasma impinging on it, thereby serving as a site for recombination of active species. In contrast, Applicant's claims include, inter alia, a generally circular cap and a stem, the stem being in thermal contact with the gas distribution portion, which serves to minimize and/or prevent species recombination since thermal contact with the gas distribution portion serves to cool the generally circular cap and stem.
In the Answer, the Examiner further explained his reasoning as follows:
To this end, the Examiner emphasizes that rudimentary thermodynamics requires all tangible materials (solid, liquid, and gas) to be "in thermal contact" via any one of the three modes of heat transfer: conduction, convection, and radiation. Thus, not only are Applicant's claimed elements "in thermal contact", but also are Kinnard's equivalents, as well as all other apparatus made by man.
The BPAI reversed the anticipation rejection, finding that the Examiner erred on all three disputed limitations. In particular, the Examiner's interpretation of "thermal contact" as covering all materials was "not well taken" by the Board:
We also note that the Examiner has not come forward with any evidence that Kinnard standoffs 54 are thermally conductive. The Examiner’s argument, based on “rudimentary thermodynamics,” that all tangible materials are in “thermal contact” via some mode of heat transfer with everything else is not well taken. The Examiner has failed to come forward with credible evidence that persons having ordinary skill in the art would have understood the “thermal contact” limitation in such an idealized fashion that it would have no meaning in the plasma-processing laboratory or workplace. Glass or ceramic rods, for example, when heated at one end, will eventually get hot, but they are very poor heat conductors, and hence very poor “thermal contacts” compared to metal rods. While it might be possible to show it that a person having ordinary skill in the art would have recognized that Kinnard used metal rods as standoffs (or, in an obviousness rejection, that it would have been obvious to do so), the Examiner has failed to make such arguments.
My two cents: Though the Board did not explain its analysis in these terms, I think the issue is best framed as claim construction rather than what the reference did or did not teach.
I don't work with semiconductors, and I don't know if the reference disclosed the thermal contact limitation. But this looks to me like a case of overreaching by the Examiner: the Examiner's overly broad interpretation doomed the rejection at the Board, even if the reference would anticipate the limitation under a more reasonable interpretation.