US 12,074,196 B2
Gradient doping epitaxy in superjunction to improve breakdown voltage
Ashish Pal, San Ramon, CA (US); Yi Zheng, Sunnyvale, CA (US); and El Mehdi Bazizi, San Jose, CA (US)
Assigned to APPLIED MATERIALS, INC., Santa Clara, CA (US)
Filed by Applied Materials, Inc., Santa Clara, CA (US)
Filed on Jul. 8, 2021, as Appl. No. 17/370,835.
Prior Publication US 2023/0008858 A1, Jan. 12, 2023
Int. Cl. H01L 29/06 (2006.01); H01L 29/66 (2006.01); H01L 29/78 (2006.01)
CPC H01L 29/0634 (2013.01) [H01L 29/66712 (2013.01); H01L 29/7802 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A method of processing a substrate, comprising:
depositing, via a first epitaxial growth process, an n-doped silicon material onto a substrate to form an n-doped layer while adjusting a ratio of dopant precursor to silicon precursor so that a dopant concentration of the n-doped layer increases from a bottom of the n-doped layer to a top of the n-doped layer;
etching the n-doped layer to form a plurality of trenches having sidewalls that are tapered and a plurality of n-doped pillars therebetween; and
filling the plurality of trenches with a p-doped material via a second epitaxial growth process to form a plurality of p-doped pillars, wherein at least one of:
the etching the n-doped layer further comprises etching a recess atop each of the plurality of trenches, wherein the recess is wider than the plurality of trenches, or
further comprising forming wells that are n-doped disposed atop or embedded within a top of each of the plurality of p-doped pillars.