Life Tech. Experiences the Practical Interplay Between Written Description and Prior Art Rejections

Life Technologies Corporation is the owner of US 13/607,128, directed to methods for detection of analytes associated with or resulting from a nucleic acid synthesis reaction. Specifically, the invention provided a method for manufacturing a chemically-sensitive FET. The inventors recognized issues with known approaches aimed at reducing possible gate oxide degradation during plasma processing. The specification explained that:

one potential issue relates to trapped charge that may be induced in the gate oxide ... during etching of metals associated with the floating gate structure ..., and how such trapped charge may affect chemFET threshold voltage Vtit Another potential issue relates to the density/porosity of the chemFET passivation layer (e.g., see [ionsensitive FET] ISFET passivation layer ...) resulting from lowtemperature aluminum metal-based CMOS fabrication. While such low temperature processes generally provide an adequate passivation layer for conventional CMOS devices, they may result in a somewhat low density and porous passivation layer which may be potentially problematic for chemFETs in contact with an analyte solution; in particular, a low-density porous passivation layer over time may absorb and become saturated with analytes or other substances in the solution, which may in turn cause an undesirable time-varying drift in the chemFETs threshold voltage Vth . This phenomenon may in turn impede accurate measurements of one or more particular analytes of interest. In view of the foregoing, other inventive embodiments disclosed herein relate to methods and apparatuses which mitigate potentially adverse effects on chemFET performance that may arise from various aspects of fabrication and post fabrication processing/handling of chemFET arrays.

The inventive method included depositing an additional passivation material on the chemically-sensitive passivation layer to reduce porosity and/or increase density. Pending claim 1 is set forth below.

claim 1.png

Life Tech. faced an examiner that took a common approach of reading the claim language of "connect" rather broadly. So, to get around the cited art, Life Tech. amended the claim to require a direct connection ("forming a diode to directly connect the floating gate structure to the semiconductor body"). This direct connection was clearly illustrated in the figures, but the specification did not use the word "directly."

And so the Examiner then turned to written description (and new matter). This is a common tactic used by examiners - take an unreasonably broad reading of the claim term (to facilitate a prior art rejection), and then when the applicant amends to claim to avoid the overly-broad interpretation, turn around and allege that the amendment is not supported. This is so common because it is virtually impossible to draft a specification with every word needed to negate an unpredictable overly-broad interpretation. And in most cases, the Examiner follows this approach since they are unable to find prior art showing the amended claim features and it is relatively little effort to maintain a rejection by turning to the malleable test for "possession" of the invention.

Here, on appeal, the Board recognized that the figures can be relied-upon to support the direct connection language since they did indeed show the direct connection as claimed. 

So, watch out for 112 rejections that seem odd - they are likely hiding an underlying deficiency with the prior art. It is often the case that issues of clarity or possession are used to cover-up for loose interpretations and areas where the cited art is lacking.