Semiconductor device and method for making the same

摘要

A semiconductor device includes: a substrate having a base and an array of semiconductor pillars extending from the base, the substrate being formed with a plurality of trenches, each of which extends into the base and has two opposing trench side walls; a first insulative liner layer formed on each of the trench side walls of each of the trenches and divided into upper and lower segments by a gap that leaves a bit-forming surface of each of the trench side walls uncovered by the first insulative liner layer; and a plurality of buried bit lines, each of which extends into the base from the bit-forming surface of a respective one of the trench side walls of each of the trenches.

主权项

1. A method for making a semiconductor device, comprising:
(a) forming a plurality of trenches in a substrate; (b) forming a first insulative liner layer on two opposing trench side walls of each of the trenches; (c) partially covering the first insulative liner layer with a bit-controlling material such that only an upper segment of the first insulative liner layer on each of the trench side walls is uncovered by the bit-controlling material; (d) forming a second insulative liner layer on the upper segment of the first insulative liner layer on each of the trench side walls, the second insulative liner layer being made from a material different from those of the first insulative liner layer and the bit-controlling material; (e) removing atop portion of the bit-controlling material and an intermediate segment of the first insulative liner layer that is covered by the top portion of the bit-controlling material so as to uncover a bit-forming surface of each of the trench side walls; and (f) diffusing a dopant into the substrate through the bit-forming surface to form a buried bit line that extends inwardly from the bit-forming surface into each of the trench side walls.