US 11,728,404 B2
Method of manufacturing a HEMT device with reduced gate leakage current, and HEMT device
Ferdinando Iucolano, Gravina di Catania (IT); and Paolo Badalá, Acireale (IT)
Assigned to STMICROELECTRONICS S.R.L., Agrate Brianza (IT)
Filed by STMICROELECTRONICS S.R.L., Agrate Brianza (IT)
Filed on Jun. 17, 2021, as Appl. No. 17/350,916.
Application 17/350,916 is a division of application No. 16/535,016, filed on Aug. 7, 2019, granted, now 11,043,574.
Claims priority of application No. 102018000007920 (IT), filed on Aug. 7, 2018.
Prior Publication US 2021/0313446 A1, Oct. 7, 2021
Int. Cl. H01L 29/66 (2006.01); H01L 21/285 (2006.01); H01L 29/20 (2006.01); H01L 29/205 (2006.01); H01L 29/47 (2006.01); H01L 29/778 (2006.01); H01L 21/28 (2006.01); C23C 14/00 (2006.01); C23C 14/06 (2006.01); C23C 14/30 (2006.01); H01L 29/417 (2006.01)
CPC H01L 29/66462 (2013.01) [H01L 21/28264 (2013.01); H01L 21/28581 (2013.01); H01L 29/2003 (2013.01); H01L 29/205 (2013.01); H01L 29/475 (2013.01); H01L 29/66431 (2013.01); H01L 29/7786 (2013.01); C23C 14/0021 (2013.01); C23C 14/0641 (2013.01); C23C 14/0676 (2013.01); C23C 14/30 (2013.01); H01L 29/41766 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A high electron mobility transistor (HEMT) device of a normally-on type, comprising:
a semiconductor heterostructure;
a dielectric layer extending over the semiconductor heterostructure and including a trench including sidewalls; and
a gate electrode extending through the trench in the dielectric layer, wherein the gate electrode is a stack, which includes:
a protection layer, made of a metal nitride with stuffed grain boundaries, extending over the semiconductor heterostructure;
a first metal layer extending over the protection layer and completely separated from the semiconductor heterostructure by said protection layer;
a second metal layer below the protection layer in contact with the semiconductor heterostructure and of a material that is able to form a Schottky junction with the semiconductor heterostructure; and
a cap layer on the first metal layer, wherein the protection layer, the first metal laver, the second metal layer, and the cap layer are each in contact with the dielectric layer at the sidewalls of the trench.