US 12,389,624 B2
High electron mobility transistor and method for forming the same
Po-Yu Yang, Hsinchu (TW); and Hsun-Wen Wang, Taipei (TW)
Assigned to UNITED MICROELECTRONICS CORP., Hsin-Chu (TW)
Filed by UNITED MICROELECTRONICS CORP., Hsin-Chu (TW)
Filed on Jul. 1, 2024, as Appl. No. 18/761,282.
Application 18/761,282 is a continuation of application No. 17/367,640, filed on Jul. 6, 2021, granted, now 12,051,740.
Claims priority of application No. 202110563682.7 (CN), filed on May 24, 2021.
Prior Publication US 2024/0355920 A1, Oct. 24, 2024
Int. Cl. H10D 30/47 (2025.01); H10D 30/01 (2025.01); H10D 62/10 (2025.01); H10D 64/01 (2025.01)
CPC H10D 30/475 (2025.01) [H10D 30/015 (2025.01); H10D 62/115 (2025.01); H10D 64/021 (2025.01)] 8 Claims
OG exemplary drawing
 
1. A high electron mobility transistor, comprising:
an epitaxial stack on a substrate;
a gate structure on the epitaxial stack, wherein the gate structure comprises a semiconductor gate layer and a metal gate layer on the semiconductor gate layer;
a passivation layer on the epitaxial stack and the gate structure; and
an air gap between the passivation layer and the gate structure and comprising:
a first portion in direct contact with a sidewall of the passivation layer, a sidewall of the metal gate layer and a top surface of the semiconductor gate layer;
a second portion in direct contact with a sidewall of the semiconductor gate layer and a top surface of the epitaxial stack; and
a third portion between a bottom surface of the passivation layer and the top surface of the epitaxial stack, wherein the second portion and the third portion form an L shape.