Semiconductor devices comprising getter layers and methods of making and using the same
Semiconductor devices comprising a getter material are described. The getter material can be located in or over the active region of the device and/or in or over a termination region of the device. The getter material can be a conductive or an insulating material. The getter material can be present as a continuous or discontinuous film. The device can be a SiC semiconductor device such as a SiC vertical MOSFET. Methods of making the devices are also described.
1. A semiconductor device comprising:
a semiconductor substrate layer of a first conductivity type;
a drift layer of a semiconductor material of the first conductivity type on the substrate layer;
a first well region of a semiconductor material of a second conductivity type different than the first conductivity type in the drift layer in a central portion of the device;
a second well region of a semiconductor material of the second conductivity type in the drift layer and spaced from the first well region in the central portion of the device;
a first source region of a semiconductor material of the first conductivity in the first well region;
a second source region of a semiconductor material of the first conductivity in the second well region;
a first gate dielectric layer on the drift layer and in contact with the first source region and the second source region;
a gate electrode on the first gate dielectric layer, the gate electrode comprising a lower surface on the first gate dielectric layer, an upper surface opposite the lower surface and sidewalls;
an interlayer dielectric material on the upper surface and adjacent the sidewalls of the gate electrode;
source ohmic contacts on the first and second source regions;
a first getter material on the source ohmic contacts and on the interlayer dielectric material;
a second getter material on the first getter material;
a getter/barrier layer on the first getter material on the interlayer dielectric material over the gate electrode and on the second getter material over the source ohmic contacts; and
a source metal on the getter/barrier layer.
2. The semiconductor device of claim 1 , further comprising a third getter material on the upper surface of the gate electrode between the gate electrode and the interlayer dielectric material.
3. The semiconductor device of claim 2 , wherein the third getter material comprises tungsten silicide.
4. The semiconductor device of claim 1 , wherein the first getter material comprises Ti and the second getter material comprises tungsten.
5. The semiconductor device of claim 1 , wherein the first getter material comprises Ti and TiN.
6. The semiconductor device of claim 1 , wherein the device is a SiC semiconductor device.
7. The semiconductor device of claim 1 , wherein the first and second getter materials each independently comprise a material selected from the group consisting of titanium, tungsten, barium, zirconium, palladium, platinum, vanadium, tin, antimony, and germanium.
8. The semiconductor device of claim 1 , wherein the getter/barrier layer comprises Ti.
9. The semiconductor device of claim 1 , further comprising:
a drain ohmic contact on the substrate opposite the drift layer; and
a drain metal on the drain ohmic contact.
10. The semiconductor device of claim 9 , wherein:
the source metal is aluminum;
the source ohmic contacts are nickel silicide;
the drain ohmic contact is nickel silicide; and/or
the drain metal comprises titanium, nickel and silver.
11. The semiconductor device of claim 1 , wherein the first conductivity type is n-type and wherein the second conductivity type is p-type.