TRANSISTORS WITH STACKED SEMICONDUCTOR LAYERS AS CHANNELS

Disclosed are transistors with stacked semiconductor layers as channels. A method of forming a semiconductor device includes depositing a p-type semiconductor layer over a portion of a semiconductor substrate, depositing a semiconductor layer over the p-type semiconductor layer, wherein the semiconductor layer is free from p-type impurities, forming a gate stack directly over a first portion of the semiconductor layer, and etching a second portion of the semiconductor layer to form a trench extending into the semiconductor layer. At least a surface of the p-type semiconductor layer is exposedto the trench. A source/drain region is formed in the trench. The source/drain region is of n-type. 本公开涉及具有堆叠半导体层作为沟道的晶体管。一种形成半导体器件的方法包括：在半导体衬底的一部分上方沉积p型半导体层；在p型半导体层上方沉积半导体层，其中，半导体层不含p型杂质；直接在半导体层的第一部分上方形成栅极堆叠；以及蚀刻半导体层的第二部分以形成延伸到半导体层中的沟槽。p型半导体层的至少一个表面暴露于沟槽。在沟槽中形成源极/漏极区域。源极/漏极区域是n型的。