Patent ID: 7994563
Filing Date: 2011-08-09
Classification: H01L

Abstract:
1. A device comprising: a substrate with a first well of a first polarity type, wherein the first well defines a varactor region, the first well comprising a lower first well boundary located above a bottom surface of the substrate; a second well in the varactor region, the second well comprises a buried well of a second polarity type having an upper second well boundary disposed below an upper portion of the first well from an upper first well boundary to the upper second well boundary and a lower second well boundary disposed above the lower first well boundary, wherein an interface of the second well and the upper portion of the first well forms a shallow PN junction in the varactor region; and a gate structure in the varactor region, the upper portion of the first well beneath the gate structure forms a channel region of the device, wherein in depletion mode, a depletion region under the gate structure in the channel region merges with a depletion region of the shallow PN junction.