Process for isolating a semiconductor layer on an insulator

Claim 2

A process for isolating a semiconductor layer on an insulator, comprising the steps of: depositing an oxide layer as a first insulator layer on a semiconductor substrate, and selectively etching the first insulator layer to open a window to the substrate; forming a semiconductor layer in the window and on the first insulating layer and converting the crystal structure of the semiconductor layer, wherein the crystal structure of the semiconductor layer is based on the crystal structure of the semiconductor substrate; patterning the semiconductor layer by a photolithographic process to form an active area having a top and sides; and forming a second insulator layer on the top and along the sides of the active area and on the first insulator layer, and isolating the active area from the substrate by forming a third insulator layer in the window by an oxidation process.

Claim 3

The process of claim 1, wherein the first insulator layer comprises silicon oxide.

Claim 4

The process of claim 1 wherein the second insulator layer is used as an oxidation-stop layer.

Claim 5

The process of claim 1, wherein the second insulator layer comprises silicon nitride.

Claim 6

The process of claim 1, wherein the semiconductor layer formed in the window and on the first insulating layer comprises polysilicon, wherein the crystal structure of the semiconductor layer is converted to the crystal structure of the semiconductor substrate.

Claim 7

The process of claim 1, wherein the semiconductor layer formed in the window and on the first insulating layer comprises amorphous silicon, wherein the crystal structure of the semiconductor layer is converted to the crystal structure of the semiconductor substrate.

Claim 8

The process of claim 1, wherein the second insulator layer formed along the sides of the active area is formed by anisotropic etching of the second insulator layer.

Claim 9

The process of claim 1, further comprising the step of removing the second insulator layer after the isolation of the active area.

Claim 10

The process of claim 1, wherein the step of forming a second insulator layer on the top and along the sides of the active area and on the first insulator layer comprises first forming a first nitride layer, patterning the first nitride layer so as to remain on the top of the active area, forming a second nitride layer, and anisotropic etching of the second nitride layer so as to form nitride side walls along the sides of the active area.

Claim 11

The process of claim 1, wherein the crystal structure of the semiconductor substrate opened by the window forms an epitaxial growth seed.

Claim 12

A process for isolating a semiconductor layer on an insulator, comprising the steps of: depositing an oxide layer as a first insulator layer on a semiconductor substrate, and opening a window to the semiconductor substrate by selectively etching the first insulator layer; depositing a semiconductor layer in the window to the semiconductor substrate and on the first insulator layer, and growing a single crystalline epitaxial semiconductor layer from the substrate through the window; forming a second insulator layer on the epitaxial semiconductor layer, and patterning the second insulator layer and the epitaxial semiconductor layer to form an active area having a top surface and sides with the second insulator area remaining on the top surface thereof; forming a third insulator layer along the sides of the active area and on the remaining second insulating layer, and forming a fourth insulator layer by oxidizing a portion of the epitaxial semiconductor layer and the semiconductor substrate in the window by diffusion of oxidant from the first insulator layer, wherein the active area is isolated from the semiconductor substrate.

Claim 13

A process for isolating a semiconductor layer on an insulator, comprising the steps of: depositing an oxide layer as a first insulator layer on a semiconductor substrate, and opening a window to the semiconductor substrate by selectively etching the first insulator layer; depositing a semiconductor layer in the window to the semiconductor substrate and on the first insulator layer, and growing a single crystalline epitaxial semiconductor layer from the substrate through the window; forming a second insulator layer on the epitaxial semiconductor layer, and patterning the second insulator layer and the epitaxial semiconductor layer to form an active area having a top surface and sides with the second insulator area remaining on the top surface thereof; forming a third insulator layer along the sides of the active area and on the remaining second insulating layer, and forming a fourth insulator layer by oxidizing a portion of the epitaxial semiconductor layer and the semiconductor substrate in the window by diffusion of oxidant from the first insulator layer, wherein the active area is isolated from the semiconductor substrate.

Claim 14

The process of claim 11, wherein the first insulator layer comprises silicon oxide.

Claim 15

The process of claim 11, wherein the second insulator layer is used as an oxidation-barrier layer.

Claim 16

The process of claim 11, wherein the second insulator layer comprises silicon nitride.

Claim 17

The process of claim 11, wherein the semiconductor layer comprises polysilicon.

Claim 18

The process of claim 11, wherein the semiconductor layer comprises amorphous silicon.

Claim 19

The process of claim 11, further comprising the step of removing the second and third insulator layers after the isolation of the active area.

Claim 20

The process of in claim 17, wherein the second and third insulating layers are removed by isotropic etching.

Claim 21

The process of claim 11, wherein the window to the semiconductor substrate forms an epitaxial growth seed.

Claim 22

A process for forming an active semiconductor area surrounded by an insulator, comprising the steps of: depositing an oxide layer as a first insulator layer on the surface of a semiconductor substrate; forming a window in the first insulator layer to the surface of the semiconductor substrate; forming a polysilicon or amorphous silicon layer over the surface of the first insulator layer and filling the window to the substrate; forming an active semiconductor layer by converting the crystal structure of the polysilicon or amorphous silicon layer based on the crystal structure of the semiconductor substrate; patterning the active semiconductor layer to form an active semiconductor area having a top and sides; forming a second insulator layer on the top and along the sides of the active semiconductor area, the second insulator layer being resistant to oxidation; forming a third insulator layer on the surface of the semiconductor substrate within the window by an oxidation process, wherein portions of the active semiconductor area and the semiconductor substrate are oxidized, wherein the active semiconductor area is isolated from the semiconductor substrate.

Claim 23

A process for forming an active semiconductor area surrounded by an insulator, comprising the steps of: depositing an oxide layer as a first insulator layer on the surface of a semiconductor substrate; forming a window in the first insulator layer to the surface of the semiconductor substrate; forming a polysilicon or amorphous silicon layer over the surface of the first insulator layer and filling the window to the substrate; forming an active semiconductor layer by converting the crystal structure of the polysilicon or amorphous silicon layer based on the crystal structure of the semiconductor substrate; patterning the active semiconductor layer to form an active semiconductor area having a top and sides; forming a second insulator layer on the top and along the sides of the active semiconductor area, the second insulator layer being resistant to oxidation; forming a third insulator layer on the surface of the semiconductor substrate within the window by an oxidation process, wherein portions of the active semiconductor area and the semiconductor substrate are oxidized, wherein the active semiconductor area is isolated from the semiconductor substrate.