Summary
This Federal Circuit opinion reviews a Patent Trial and Appeal Board final written decision holding certain claims of U.S. Patent 6,774,033 unpatentable as obvious. The appellant challenged the Board’s claim construction of the term “comprising tungsten,” arguing it should be limited to elemental tungsten rather than including compounds. While the appellate court agreed that the Board’s construction was erroneous, it found the error harmless because the prior art reference independently taught both elemental tungsten and tungsten silicide. The court ultimately affirmed the Board’s obviousness determination.
Topics
Practice areas
Questions Presented
- Whether the Board erred in construing the term “comprising tungsten” in the challenged claims.
- Whether, assuming the correct construction, the Board’s obviousness findings are supported by substantial evidence.
Holdings
- The Board’s construction was erroneous because “comprising tungsten” requires elemental tungsten, but the error was harmless and does not affect the obviousness determination.
- The Board’s obviousness findings are affirmed because the prior‑art reference Trivedi teaches both elemental tungsten and tungsten‑silicide, each of which renders the claims obvious, and the Board’s factual findings are supported by substantial evidence.
Key quotations
“The term “comprising tungsten,” as recited in the challenged claims, requires elemental tungsten.” (*5)
“The Board’s finding that Trivedi discloses both a tungsten‑silicide and an elemental tungsten layer, and that either would render the claim obvious, is supported by substantial evidence.” (*9)
Factual background
The ’033 patent claims a method of forming a local interconnect layer using a titanium‑nitride first film and a tungsten second film. The dispute centered on whether the term “comprising tungsten” required elemental tungsten or could include tungsten compounds. The Board construed the term to include compounds, while HDSS argued it required elemental tungsten. The prior‑art reference Trivedi disclosed both elemental tungsten and tungsten‑silicide layers.
Procedural history
The Board held claims 1–7 and 9–17 of U.S. Patent 6,774,033 unpatentable as obvious. HD Silicon Solutions LLC appealed. The Federal Circuit reviewed the Board's claim construction de novo and the obviousness findings for substantial‑evidence support.