VTT Technical Research Centre of Finland Ltd. v. SiTime Corporation

Background

VTT brought a patent-infringement action against SiTime involving U.S. Patent No. 8,558,643, titled “Micromechanical Device Including N-Type Doping for Providing Temperature Compensation and Method of Designing Thereof.” The patent concerns semiconductor-based micromechanical devices whose temperature sensitivity is managed by using regions with different material properties, doping, crystal orientations, and relative volumes. The parties presented disputes about the meaning of several claim terms.

“At least two regions having different material properties”

The court construed this term to mean “at least two regions within the semiconductor element that have different material properties.” The court held that the regions must be inside the semiconductor element because the claims describe the element as comprising those regions. But the court declined to require that the regions be either distinct regions or a continuous gradient. It also declined to add SiTime’s proposed requirement that the regions be designed so their temperature coefficients cancel each other to the claimed level, reasoning that other claim limitations already address the cancellation effect.

Opposite temperature sensitivities

For the claim 1 term concerning regions whose generalized-stiffness temperature sensitivities are opposite in sign, the court adopted a construction requiring that, at least at one temperature, the generalized stiffness of one region increase as temperature increases while the generalized stiffness of a second region decreases. The construction also applies the opposite relationship when temperature decreases. The court rejected a proposed requirement that two regions have exactly equal and opposite temperature coefficients, because the patent describes weighted effects and embodiments involving multiple regions in which exact equality between two regions is unnecessary.

Temperature-drift limitation in claim 29

Claim 29 stated that the semiconductor element’s overall temperature drift was less than 50 parts per million but omitted a temperature range. The court found that omission to be an obvious error that could be corrected. Based on the claims, specification, and prosecution history, the court corrected claim 29 to add a temperature range of at least 100 degrees Celsius. The court therefore found that claim 29 was not indefinite for lacking a temperature range. The court did not adopt SiTime’s proposed requirement that the limitation apply over any and all temperature ranges.

“Drive or sense means”

The court held that “drive or sense means” is governed by 35 U.S.C. § 112(f), the statute governing means-plus-function limitations. Under that rule, the claim covers the function stated in the claim and the corresponding structure disclosed in the patent, along with equivalents.

The court identified the claimed functions as driving the semiconductor element, sensing it, or driving and sensing it. The specification disclosed a transducer linked to the driving function. But the court found no corresponding structure linked to the sensing function. Because the specification did not disclose adequate structure for all the claimed functions, the court held that the claims containing “drive or sense means” are indefinite.

Disposition

The court adopted the listed constructions, corrected claim 29 by adding the 100-degree-Celsius temperature range, and found all asserted claims of the patent containing the “drive or sense means” limitation indefinite. The order stated that it terminated docket number 63.