Alpha and Omega Semiconductor Ltd. ("AOS") has filed a complaint against Fairchild Semiconductor, in the United States District Court for the Northern District of California. Among other things, the complaint asserts that Fairchild Semiconductor infringes U.S. Patent No. 5,907,776 and No. 5,767,567 owned by AOS, both dealing with MOSFET technology.
Patent #5,767,567 is titled "Design of Layout for Integration with Power MOSFET Packaging to Achieve Better Lead Wire Connections and Lower On Resistance." According to the abstract, "The present invention discloses a MOSFET power IC device formed in a semiconductor chip including a source contact area which is provided for connecting to a lead-frame via a several of lead-wires. The power IC device includes many lead-wire contact points on the source contact area for securely attaching the lead wires onto the source contact area. These lead-wire contact points are uniformly distributed substantially over the source contact area thus the spread resistance is reduced whereby the device on-resistance and device performance may be improved."
Patent#5,907,776 is titled "Method of Forming a Semiconductor Structure Having Reduced Threshold Voltage and High Punch-through Tolerance." The abstract states, "A power MOSFET device formed on a semiconductor substrate having a body region of a first conductivity type diffused in a semiconductor substrate with an epitaxial layer of a second conductivity type. There is also a source region of a second conductivity type formed in the body region. A portion of the body region adjacent to the source region is compensated by ion implanting a material of the second conductivity type in the portion of the body region such that the impurity concentration of the body region at the portion is reduced. As a consequence, with reduced impurity charge in the body region adjacent to the source, the threshold voltage of the MOSFET device is lowered but at no comprise in punch-through tolerance because the reduction in charge is remote from the origin of the depletion layer which is located at the boundary between the body."
AOS stated that it filed this lawsuit to protect its valuable intellectual property rights, after AOS attempted to resolve this dispute through reasonable negotiations for some time without success. AOS states that it remains open to further negotiations, but is prepared to do what it takes to protect its technology.
Fairchild has declined to comment on the complaint as of 1 p.m., May 18, 2007.
