ENTech Instruments Inc v. SILCoTek Corp

1. Case Identification

• Case #: IPR2017-00354
• Patent #: 6,511,760
• Filed: November 29, 2016
• Petitioner(s): Entech Instruments, Inc.
• Patent Owner(s): Silcotek Corporation
• Challenged Claims: 1-20

2. Patent Overview

• Title: Method for Passivating the Interior Surface of a Gas Storage Vessel
• Brief Description: The ’760 patent discloses a method for passivating the interior surface of a gas storage vessel to protect it from corrosion. The method involves introducing silicon hydride gas (silane), heating it under pressure to decompose the gas and deposit a silicon layer, and controlling the deposition duration to prevent the formation of silicon dust.

3. Grounds for Unpatentability

Ground 1: Anticipation and Obviousness over Rohwer - Claims 1 and 4-8 are anticipated by, or in the alternative obvious over, Rohwer.

• Prior Art Relied Upon: Rohwer (“Deactivation, Coating, and Performance of Nickel Capillary Columns for GLC,” a 1986 journal article).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Rohwer, which discloses a passivation process for nickel tubing used as a gas chromatograph column, anticipates every limitation of claim 1. Petitioner asserted that such tubing is a "gas storage vessel" under a proper claim construction. Rohwer was argued to teach all claimed method steps: dehydrating the vessel by flushing with nitrogen at 380°C; introducing silane gas; heating (380°C) and pressurizing (250 kPa) the silane to deposit a silicon layer; controlling the duration (3 hours) to be within the ’760 patent’s specified range (30 mins to 4 hours) for preventing dust; purging the vessel; and cooling it. Petitioner contended Rohwer's single deposition cycle coated the entire surface, making the conditional "cycling" step of claim 1 unnecessary and thus met.
  • Motivation to Combine (for §103 grounds): For the alternative obviousness argument, Petitioner asserted that all process parameters in Rohwer are either explicitly taught or would have been obvious modifications. For example, the dehydration and purging steps were taught by Rohwer to avoid unwanted silicide formation and dust, respectively, making their use an obvious process choice.
  • Expectation of Success (for §103 grounds): A POSITA would have a high expectation of success as Rohwer provides a complete, working process for achieving the same goal of passivation with a dust-free silicon layer.

Ground 2: Obviousness over Rohwer and Briesacher - Claims 15 and 20 are obvious over Rohwer in view of Briesacher.

• Prior Art Relied Upon: Rohwer and Briesacher (Patent 5,238,469).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground addressed product claims 15 and 20, which recite a corrosion-resistant gas storage vessel with specific surface roughness (RA) and silicon layer thickness values. Petitioner argued Rohwer discloses the passivated vessel and the method of its creation, while Briesacher supplies the conventional RA values for such vessels. Rohwer discloses a silicon layer thickness of 240-320 angstroms, meeting the 120-500 angstrom range of claim 15. Briesacher teaches that a "well known" and desirable RA for electropolished gas vessels is between 5-25 microinches, satisfying the "< about 20 microinches" limitation of claim 15.
  • Motivation to Combine (for §103 grounds): A POSITA would combine Rohwer’s effective passivation process with Briesacher’s industry-standard surface preparation to create a high-quality, reliable, and inert gas storage vessel. Using a well-known surface finish for a component intended for gas chromatography was a predictable design choice to ensure optimal performance.
  • Expectation of Success (for §103 grounds): Applying a known passivation method to a vessel with a standard, commercially desirable surface finish was a straightforward combination of known elements to achieve a predictable result.

Ground 3: Obviousness over Rohwer, Zou, and Briesacher - Claims 9-20 are obvious over Rohwer in view of Zou and Briesacher.

• Prior Art Relied Upon: Rohwer, Briesacher, and Zou (“Stainless Steel Capillary Columns for High Temperature Gas Chromatography,” a 1993 journal article).

• Core Argument for this Ground:

  • Prior Art Mapping: This combination addressed claims requiring multiple deposition cycles to form "sublayers" of silicon and RA-dependent processing steps. Zou was cited for its teaching of repeating silicon deposition treatments "several times" to create a thicker silicon film (e.g., 3,000-5,000 angstroms). This directly taught the formation of a silicon layer from a "plurality of sublayers" (claim 13) and the cycling steps contingent on RA values (claims 10 and 17). Rohwer provided the foundational single-cycle process, and Briesacher provided the standard RA values.
  • Motivation to Combine (for §103 grounds): A POSITA would be motivated to modify Rohwer's single-cycle process by incorporating Zou's teaching of repeated cycles to create a thicker, more durable passivation layer suitable for high-temperature applications, which was Zou's explicit goal. This modification represents a simple optimization to enhance a known process.
  • Expectation of Success (for §103 grounds): Repeating a known deposition step to achieve a thicker layer was a predictable application of a known technique to achieve a desired, known result.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including claims 2-3 over Rohwer alone and claims 1-8 over Rohwer and Zou, which relied on similar arguments regarding obvious process modifications.

4. Key Claim Construction Positions

• "gas storage vessel": Petitioner argued this term should be construed broadly to mean any vessel capable of storing gas, including the tubular gas chromatography columns disclosed in Rohwer and Zou. This construction was central to applying the teachings of those references, which focused on chromatography components rather than large storage tanks.
• "substantially free of silicon dust": Petitioner proposed this phrase should be construed as the natural result of performing the claimed process within the specified parameters (time, temperature, pressure), rather than as a limitation requiring a specific, measurable dust concentration.
• "cycling... until the entire interior surface... is covered": Petitioner argued this was a conditional limitation that does not need to be performed if the initial deposition cycle achieves full surface coverage. This was key to the anticipation argument, as Rohwer's process involved only a single, successful deposition cycle.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-20 of Patent 6,511,760 as unpatentable.