High electron mobility transistor and method for forming the same
A high electron mobility transistor (HEMT) includes a substrate, a channel layer on the substrate, a barrier layer on the channel layer, a gate structure on the barrier layer, a gate spacer on the gate structure, and a gate contact on the gate spacer. The gate contact includes a first portion and a second portion respectively at two sides of the gate spacer and directly contacting the gate structure.
1 . A high electron mobility transistor, comprising:
a substrate;
a channel layer disposed on the substrate;
a barrier layer disposed on the channel layer;
a gate structure disposed on the barrier layer;
a gate spacer disposed on the gate structure, wherein the gate spacer is made of a dielectric material; and
a gate contact disposed on the gate spacer and comprising a first portion and a second portion respectively at two sides of the gate spacer and directly contacting the gate structure, wherein the gate structure comprises a first Schottky contact region being contacted by the first portion and a second Schottky contact region being contacted by the second portion.
2 . The high electron mobility transistor according to claim 1 , wherein the first portion comprises a first width, the second portion comprises a second width, the gate spacer comprises a spacer width, the gate structure comprises a gate width, wherein the first width and the second width are the same.
3 . The high electron mobility transistor according to claim 2 , wherein the first width, the second width, and the spacer width are the same.
4 . The high electron mobility transistor according to claim 2 , wherein a sum of the first width, the second width, and the spacer width is smaller than the gate width.
5 . The high electron mobility transistor according to claim 1 , wherein an outer sidewall of the first portion and an outer sidewall of the second portion are pulled back from a sidewall of the gate structure to the gate spacer by a distance, respectively.
6 . The high electron mobility transistor according to claim 1 , wherein the first Schottky contact region, the second Schottky contact region, and a top surface of the gate structure directly under the gate spacer are not coplanar.
7 . The high electron mobility transistor according to claim 1 , further comprising:
a passivation layer on the barrier layer and the gate structure, wherein the gate contact further comprises a connecting portion located on the gate spacer and the passivation layer and connecting between the first portion and the second portion; and
a source contact and a drain contact respectively at two sides of the gate structure, penetrating through the passivation layer and the barrier layer to contact the channel layer.
8 . The high electron mobility transistor according to claim 7 , wherein the first portion, the second portion, and the connecting portion are monolithic in structure.
9 . The high electron mobility transistor according to claim 7 , wherein the gate spacer and the passivation layer comprise a same dielectric material.
10 . The high electron mobility transistor according to claim 1 , wherein in a plane view, the first portion, the second portion, and the gate structure extend along a same direction.