Method for forming thin silicon membrane or beam

Claim 1

A method for forming thin suspended membranes or layers of single crystal silicon suitable for use as microbridges and diaphragms in microaccelerometers and pressure sensors comprising the following steps: providing a silicon substrate oriented essentially along a single crystallographic plane having a front and back surface which are substantially parallel to each other; forming a blanket layer of silicon oxide overlaying said front surface of said silicon substrate; patterning said blanket layer of silicon oxide so as to form a plurality of silicon oxide strips in spaced relationship with each other, said silicon oxide strips are spaced so that the underlying silicon substrate is exposed a gaps disposed between adjacent pairs of said strips; selectively epitaxially depositing monocrystalline silicon onto said silicon substrate exposed at said gaps and then laterally from said gap over said silicon oxide strips so as to form a substantially continuous layer of epitaxial silicon over said plurality of silicon oxide strips; masking said back surface of said silicon substrate so as to expose a desired pattern of said back surface of said silicon substrate; and removing said exposed silicon from said back surface of said silicon substrate in said desired pattern; whereas said removing step is substantially terminated at said silicon oxide strips so as to form suspended regions containing said epitaxial silicon overlaying said silicon oxide strips.

Claim 2

A method for forming thin suspended membranes or layers of single crystal silicon suitable for use as microbridges and diaphragms in microaccelerometers and pressure sensors comprising the following steps: providing a silicon substrate oriented essentially along a single crystallographic plane having a front and back surface which are substantially parallel to each other; forming a blanket layer of silicon oxide overlaying said front surface of said silicon substrate; patterning said blanket layer of silicon oxide so as to form a plurality of silicon oxide strips in spaced relationship with each other, said silicon oxide strips are spaced so that the underlying silicon substrate is exposed a gaps disposed between adjacent pairs of said strips; selectively epitaxially depositing monocrystalline silicon onto said silicon substrate exposed at said gaps and then laterally from said gap over said silicon oxide strips so as to form a substantially continuous layer of epitaxial silicon over said plurality of silicon oxide strips; masking said back surface of said silicon substrate so as to expose a desired pattern of said back surface of said silicon substrate; and removing said exposed silicon from said back surface of said silicon substrate in said desired pattern; whereas said removing step is substantially terminated at said silicon oxide strips so as to form suspended regions containing said epitaxial silicon overlaying said silicon oxide strips.

Claim 3

A method for forming thin suspended membranes or layers of single crystal silicon suitable for use as microbridges and diaphragms in microaccelerometers and pressure sensors comprising the following steps: providing a silicon substrate oriented essentially along a single crystallographic plane having a front and back surface which are substantially parallel to each other; forming a blanket layer of silicon oxide overlaying said front surface of said silicon substrate; patterning said blanket layer of silicon oxide so as to form a plurality of silicon oxide strips in spaced relationship with each other, each of said silicon oxide strips characterized essentially by said predetermined thickness, said silicon oxide strips are spaced so that the underlying silicon substrate is exposed a gaps disposed between adjacent pairs of said beams, the width of each gap is less than or equal to about 1.4 times said predetermined thickness of said silicon oxide strips; selectively growing single crystal epitaxial silicon on said silicon substrate up through said gaps by vertical epitaxial deposition and then laterally growing single crystal epitaxial silicon over said silicon oxide strips by lateral epitaxial deposition until lateral deposition from adjacent gaps merges, so as to form a substantially continuous layer of epitaxial silicon over said plurality of silicon oxide strips; masking said back surface of said silicon substrate so as to expose a desired pattern of said back surface of said silicon substrate; and removing said exposed silicon from said back surface of said silicon substrate in said desired pattern; whereas said removing step is substantially terminated at said silicon oxide strips and within said gaps so as to form suspended regions containing said epitaxial silicon overlaying said silicon oxide strips.

Claim 4

A method for forming thin suspended membranes or layers of single crystal silicon suitable for use as microbridges and diaphragms in microaccelerometers and pressure sensors comprising the following steps: providing a silicon substrate oriented essentially along a single crystallographic plane having a front and back surface which are substantially parallel to each other; forming a blanket layer of silicon oxide overlaying said front surface of said silicon substrate; patterning said blanket layer of silicon oxide so as to form a plurality of silicon oxide strips in spaced relationship with each other, each of said silicon oxide strips characterized essentially by said predetermined thickness, said silicon oxide strips are spaced so that the underlying silicon substrate is exposed a gaps disposed between adjacent pairs of said beams, the width of each gap is less than or equal to about 1.4 times said predetermined thickness of said silicon oxide strips; selectively growing single crystal epitaxial silicon on said silicon substrate up through said gaps by vertical epitaxial deposition and then laterally growing single crystal epitaxial silicon over said silicon oxide strips by lateral epitaxial deposition until lateral deposition from adjacent gaps merges, so as to form a substantially continuous layer of epitaxial silicon over said plurality of silicon oxide strips; masking said back surface of said silicon substrate so as to expose a desired pattern of said back surface of said silicon substrate; and removing said exposed silicon from said back surface of said silicon substrate in said desired pattern; whereas said removing step is substantially terminated at said silicon oxide strips and within said gaps so as to form suspended regions containing said epitaxial silicon overlaying said silicon oxide strips.

Claim 7

A method for forming thin suspended membranes or layers of single crystal silicon suitable for use as microbridges and diaphragms in microaccelerometers and pressure sensors comprising the following steps: providing a silicon substrate oriented essentially along the <100> crystallographic plan having a front and back surface which are substantially parallel to each other; forming a blanket layer of silicon oxide overlaying said front surface of said silicon substrate; patterning said blanket layer of silicon oxide so as to form a plurality of silicon oxide strips in spaced relationship with each other, each of said silicon oxide strips characterized essentially by said predetermined thickness, said silicon oxide strips are spaced so that the underlying silicon substrate is exposed at gaps disposed between adjacent pairs of said beams, the width of each gap is less than or equal to about 1.4 times said predetermined thickness of said silicon oxide strips; selectively growing single crystal silicon by epitaxial deposition onto said silicon substrate exposed at said gaps and then laterally into mutual merger over said silicon oxide strips so as to form a substantially continuous layer of epitaxial silicon over said plurality of silicon oxide strips; masking said back surface of said silicon substrate so as to expose a desired pattern of said back surface of said silicon substrate; and removing said exposed silicon from said back surface of said silicon substrate in said desired pattern; whereas said removing step is substantially terminated at said silicon oxide strips and within said gaps so as to form suspended regions containing said epitaxial silicon overlaying said silicon oxide strips.

Claim 8

A method for forming thin suspended membranes or layers of single crystal silicon suitable for use as microbridges and diaphragms in microaccelerometers and pressure sensors comprising the following steps: providing a silicon substrate oriented essentially along the <100> crystallographic plan having a front and back surface which are substantially parallel to each other; forming a blanket layer of silicon oxide overlaying said front surface of said silicon substrate; patterning said blanket layer of silicon oxide so as to form a plurality of silicon oxide strips in spaced relationship with each other, each of said silicon oxide strips characterized essentially by said predetermined thickness, said silicon oxide strips are spaced so that the underlying silicon substrate is exposed at gaps disposed between adjacent pairs of said beams, the width of each gap is less than or equal to about 1.4 times said predetermined thickness of said silicon oxide strips; selectively growing single crystal silicon by epitaxial deposition onto said silicon substrate exposed at said gaps and then laterally into mutual merger over said silicon oxide strips so as to form a substantially continuous layer of epitaxial silicon over said plurality of silicon oxide strips; masking said back surface of said silicon substrate so as to expose a desired pattern of said back surface of said silicon substrate; and removing said exposed silicon from said back surface of said silicon substrate in said desired pattern; whereas said removing step is substantially terminated at said silicon oxide strips and within said gaps so as to form suspended regions containing said epitaxial silicon overlaying said silicon oxide strips.

Claim 10

A method for forming thin suspended membranes or layers of single crystal silicon suitable for use as microbridges and diaphragms in microaccelerometers and pressure sensors comprising the following steps: providing a silicon substrate oriented essentially along a single crystallographic plane having a front and back surface which are substantially parallel to each other; forming a first blanket layer of silicon oxide overlaying said front surface of said silicon substrate; patterning said first blanket layer of silicon oxide so as to form a plurality of silicon oxide strips in spaced relationship with each other, said silicon oxide strips are spaced so that the underlying silicon substrate is exposed at gaps disposed between adjacent pairs of said beams; selectively growing single crystal silicon by vertical epitaxial deposition onto said silicon substrate exposed at said gaps and then by lateral epitaxial deposition over said silicon oxide strips at least until lateral deposition fronts from all adjacent gaps meet along their entire length, so as to form a substantially continuous layer of epitaxial silicon over said plurality of silicon oxide strips; forming a second blanket layer of silicon oxide over said substantially continuous layer of epitaxial silicon; masking said back surface of said silicon substrate so as to expose a desired pattern of said back surface of said silicon substrate; and removing said exposed silicon from said back surface of said silicon substrate in said desired pattern; whereby said removing step is substantially terminated at said second blanket layer of silicon oxide so as to form suspended regions containing said epitaxial silicon overlaying said silicon oxide strips.

Claim 11

A method for forming thin suspended membranes or layers of single crystal silicon suitable for use as microbridges and diaphragms in microaccelerometers and pressure sensors comprising the following steps: providing a silicon substrate oriented essentially along a single crystallographic plane having a front and back surface which are substantially parallel to each other; forming a first blanket layer of silicon oxide overlaying said front surface of said silicon substrate; patterning said first blanket layer of silicon oxide so as to form a plurality of silicon oxide strips in spaced relationship with each other, said silicon oxide strips are spaced so that the underlying silicon substrate is exposed at gaps disposed between adjacent pairs of said beams; selectively growing single crystal silicon by vertical epitaxial deposition onto said silicon substrate exposed at said gaps and then by lateral epitaxial deposition over said silicon oxide strips at least until lateral deposition fronts from all adjacent gaps meet along their entire length, so as to form a substantially continuous layer of epitaxial silicon over said plurality of silicon oxide strips; forming a second blanket layer of silicon oxide over said substantially continuous layer of epitaxial silicon; masking said back surface of said silicon substrate so as to expose a desired pattern of said back surface of said silicon substrate; and removing said exposed silicon from said back surface of said silicon substrate in said desired pattern; whereby said removing step is substantially terminated at said second blanket layer of silicon oxide so as to form suspended regions containing said epitaxial silicon overlaying said silicon oxide strips.