US 12,170,328 B2
P type gallium nitride conformal epitaxial structure over thick buffer layer
Tatsuya Tominari, Plano, TX (US); Nicholas Stephen Dellas, Dallas, TX (US); and Qhalid Fareed, Plano, TX (US)
Assigned to TEXAS INSTRUMENTS INCORPORATED, Dallas, TX (US)
Filed by Texas Instruments Incorporated, Dallas, TX (US)
Filed on Dec. 15, 2020, as Appl. No. 17/121,992.
Prior Publication US 2022/0190148 A1, Jun. 16, 2022
Int. Cl. H01L 29/778 (2006.01); H01L 29/04 (2006.01); H01L 29/20 (2006.01); H01L 29/205 (2006.01); H01L 29/66 (2006.01)
CPC H01L 29/7786 (2013.01) [H01L 29/045 (2013.01); H01L 29/2003 (2013.01); H01L 29/205 (2013.01); H01L 29/66462 (2013.01); H01L 29/7787 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A semiconductor device, comprising:
a silicon substrate;
a buffer layer of III-N semiconductor material over the silicon substrate, wherein:
the buffer layer includes a columnar region having a first thickness;
the buffer layer includes a transition region surrounding the columnar region; and
the buffer layer includes an inter-columnar region around the transition region, the inter-columnar region having a second thickness, the first thickness being greater than the second thickness; and
the buffer layer has a (0001) crystal orientation, wherein a c-plane of the III-N semiconductor material of the buffer layer is parallel to a boundary plane between the buffer layer and the silicon substrate, and wherein a top surface in the inter-columnar region has a higher portion of surfaces off of the c-plane than a top surface in the columnar region; and
a gallium nitride field effect transistor (GaN FET), including:
a barrier layer of III-N semiconductor material over the buffer layer, the barrier layer extending across the columnar region and the transition region; and
a gate of p-type III-N semiconductor material over the barrier layer, the gate extending over the columnar region and the transition region, wherein:
the gate has a first gate thickness over the columnar region and a second gate thickness over the transition region;
both the first gate thickness and the second gate thickness are thicker than twice a vertical range of the top surface in the columnar region; and
a difference between the first gate thickness and the second gate thickness is less than half the vertical range of the top surface in the columnar region.