RF switch device and method of manufacturing same
An RF switch device and a method of manufacturing the same deplete the lower region of the device to reduce coupling with a substrate and thereby improve RF characteristics by forming a depletion control region surrounding source and drain regions to control a depletion region while protecting a channel region within an active region where well regions such as PW and DNW are not formed.
1 . A radio frequency (RF) switch device, comprising:
a substrate;
a device isolation film disposed in the substrate, a bottom of the device isolation film being positioned at a first depth;
a gate electrode disposed on the substrate;
a source region disposed on a surface side of the substrate;
a drain region spaced apart from the source region on the surface side of the substrate; and
a depletion control region surrounding the source region and the drain region within the substrate, a bottom of the depletion control region being positioned at a second depth,
wherein the second depth of the depletion control region is less the first depth of the device isolation film such that the substrate has a substantially uniform impurity concentration below the depletion control region, and
wherein the source region and the drain region are regions doped with an impurity of a second conductivity type, and the depletion control region is a region doped with an impurity of a first conductivity type.
2 . The RF switch device of claim 1 , wherein the depletion control region is formed within the substrate, extending to a depth substantially identical to that of the bottom of the device isolation film.
3 . The RF switch device of claim 1 , wherein the depletion control region is doped with the impurity of the first conductivity type at a concentration ranging from 5×10 11 ions/cm 2 to 1×10 13 ions/cm 2 .
4 . The RF switch device of claim 1 , wherein the substrate has a resistivity of 100 ohm·cm or higher.
5 . The RF switch device of claim 1 , further comprising:
a pair of lightly doped drain (LDD) regions being in contact with the source region and the drain region, respectively, on the surface side of the substrate.
6 . The RF switch device of claim 5 , wherein the pair of LDD regions are positioned at a shallower depth from a surface of the substrate compared to the source region and the drain region.
7 . The RF switch device of claim 1 , further comprising:
a silicide film disposed on the source region, the drain region, and the gate electrode.
8 . An RF switch device, comprising:
a substrate of a first conductivity type with a resistivity of 1000 ohm·cm or higher,
a device isolation film disposed in the substrate;
a gate electrode disposed on the substrate;
a source region of a second conductivity type disposed on a surface side of the substrate;
a drain region of the second conductivity type spaced apart from the source region on the surface side of the substrate; and
a depletion control region of the first conductivity type surrounding the source region and the drain region within the substrate,
wherein a bottom of the depletion control region is disposed at a shallower depth within the substrate compared to a bottom of the device isolation film, and the substrate maintains a substantially uniform impurity concentration below the depletion control region, and
wherein the source region and the drain region are regions doped with an impurity of the second conductivity type, and the depletion control region is a region doped with an impurity of the first conductivity type.