Techniques and Structure for Forming Thin Silicon-on-Insulator Materials

Patent metadata

Field	Value
Publication number	US-2019027396-A1
Application number	US-201715728000-A
Country	US
Kind code	A1
Filing date	Oct 9, 2017
Priority date	Jul 24, 2017
Publication date	Jan 24, 2019
Grant date	—

Abstract

A method may include providing a silicon-on-insulator (SOI) substrate, the SOI substrate comprising an insulator layer and a silicon layer. The silicon layer may be disposed on the insulator layer, where the silicon layer comprises a first silicon thickness variation. The method may include forming an oxide layer on the silicon layer, where the oxide layer has a uniform thickness. The method may include selectively etching the oxide layer on the silicon layer, wherein the oxide layer comprises a first non-uniform oxide thickness. After thermal processing of the SOI substrate in an oxygen ambient, the non-uniform oxide thickness may be configured to generate a second silicon thickness variation in the silicon layer, less than the first silicon thickness variation.

First claim

What is claimed is:

1 . A method, comprising:
providing a silicon-on-insulator (SOI) substrate, the SOI substrate comprising:
an insulator layer: and
a silicon layer, the silicon layer disposed on the insulator layer, the silicon layer comprising a first silicon thickness variation;
forming an oxide layer on the silicon layer, the oxide layer having a uniform thickness; and selectively etching the oxide layer on the silicon layer, wherein the oxide layer comprises a non-uniform oxide thickness, wherein after thermal processing of the SOI substrate in an oxygen ambient, the non-uniform oxide thickness is configured to generate a second silicon thickness variation in the silicon layer, less than the first silicon thickness variation.

2 . The method of claim 1 , wherein a first thickness of the oxide layer is removed at a first position of the substrate, wherein a second thickness of the oxide layer is removed at a second position of the substrate, the second thickness being greater than the first thickness, wherein, before the selectively forming the oxide layer, the silicon layer comprises a first silicon thickness at the first position, wherein the silicon layer comprises a second silicon thickness at the second position, wherein the second silicon thickness is greater than the first silicon thickness.

3 . The method of claim 2 , wherein the selectively etching comprises:
providing the substrate in a process chamber, adjacent a plasma chamber; extracting an ion beam from the plasma chamber into the process chamber through an extraction aperture; and performing an etch treatment of the substrate, the etch treatment comprising performing at least one scan wherein the substrate is scanned with respect to the extraction aperture, when the substrate is exposed to the ion beam.

4 . The method of claim 3 , wherein the performing the at least one scan comprises:
scanning the substrate at a first velocity when the first position is exposed to the ion beam: and scanning the substrate at a second velocity when the second position is exposed to the ion beam, the first velocity being greater than the second velocity.

5 . The method of claim 3 , wherein the performing the at least one scan comprises:
generating the ion beam as a pulsed ion beam; directing the ion beam to the oxide layer at a first duty cycle at the first position; and directing the ion beam to the oxide at a second duty cycle at the second position, the second duty cycle being greater than the first duty cycle.

6 . The method of claim 3 , further comprising:
receiving a silicon thickness profile before the selectively etching the oxide layer, the silicon thickness profile comprising a plurality of data sets, wherein a given data set of the plurality of data sets comprises a substrate position and a silicon layer thickness corresponding to the substrate position, and wherein the plurality of data sets includes the first position and the second position.

7 . The method of claim 6 , wherein the performing the selectively etching comprises etching the oxide layer to match the silicon thickness profile, wherein the oxide layer is etched to a greater extent at a given position where silicon thickness is relatively greater, as compared to another given position where silicon thickness is relatively lesser.

8 . The method of claim 1 , wherein before the selectively etching, the oxide layer comprises an initial oxide thickness, wherein the initial oxide thickness is adjusted to compensate for the first silicon thickness variation, wherein the initial oxide thickness is greater for a greater first silicon thickness variation.

9 . The method of claim 1 , wherein before the forming the oxide layer, the silicon layer comprises a maximum thickness of 30 nm or less.

10 . The method of claim 3 , wherein the extraction aperture comprises an elongated shape, wherein the ion beam comprises a ribbon ion beam having a beam length along a long axis of the extraction aperture, the beam length being greater than or equal to a width of the substrate, the etch treatment comprising a plurality of scans, wherein a twist angle of the substrate with respect to a perpendicular plane to a plane of the substrate is varied between successive scans of the plurality of scans.

11 . A method, comprising:
providing a silicon-on-insulator (SOI) substrate, the SOI substrate comprising:
an insulator layer: and
a silicon layer, the silicon layer disposed on the insulator layer, the silicon layer comprising a first silicon thickness variation; and
selectively forming an oxide layer in the silicon layer, wherein the oxide layer comprises a non-uniform oxide thickness, wherein after the selectively forming the oxide layer the silicon layer exhibits a second silicon thickness variation, less than the first silicon thickness variation.

12 . The method of claim 11 , wherein a first thickness of the oxide layer is formed at a first position of the substrate, wherein a second thickness of the oxide layer is formed at a second position of the substrate, the second thickness being greater than the first thickness, wherein, before the selectively forming the oxide layer, the silicon layer comprises a first silicon thickness at the first position, wherein the silicon layer comprises a second silicon thickness at the second position, wherein the second silicon thickness is greater than the first silicon thickness.

13 . The method of claim 12 , wherein the selectively forming the oxide layer comprises:
providing the substrate in a process chamber, adjacent a plasma chamber; extracting an ion beam from the plasma chamber into the process chamber through an extraction aperture, the ion beam comprising oxygen ions; and performing at least one scan wherein the substrate is scanned with respect to the extraction aperture when the substrate is exposed to the oxygen ions.

14 . The method of claim 13 , wherein the performing the at least one scan comprises:
scanning the substrate at a first velocity when the first position is exposed to the ion beam; and scanning the substrate at a second velocity when the second position is exposed to the ion beam, the first velocity being greater than the second velocity.

15 . The method of claim 13 , wherein the ion beam is extracted from a pulsed plasma, the pulsed plasma comprising a plasma power pulse period wherein a plasma power is pulsed from a first power level to a second power level within the plasma power pulse period, wherein the ion beam is directed to the substrate in a first plasma power duty cycle at the first position, wherein the ion beam is directed to the substrate in a second plasma power duty cycle at the second position, wherein the second plasma power duty cycle is greater than the first plasma power duty cycle.

16 . The method of claim 13 , wherein the ion beam is extracted using a pulsed DC bias, the pulsed DC bias comprising a DC bias pulse period wherein a DC bias is pulsed from a non-zero bias to a zero bias within the DC bias pulse period, wherein the ion beam is directed to the substrate in a first DC bias duty cycle at the first position, wherein the ion beam is directed to the substrate in a second DC bias duty cycle at the second position, wherein the second DC bias duty cycle is greater than the first DC bias duty cycle.

17 . The method of claim 13 , wherein the ion beam is extracted using a pulsed DC bias voltage, the pulsed DC bias voltage varying from a first bias voltage when the ion beam is directed to the substrate at the first position, to a second b

Assignees

• Varian Semiconductor Equipment Ass Inc

Inventors

• Waite Andrew M
• Evans Morgan D
• Hautala John

Classifications

• H10P50/283

  by chemical means · CPC title

• H10P50/242

  of Group IV materials · CPC title

• H10P14/69215

  the material being a silicon oxide, e.g. SiO2 · CPC title

• H10P14/6322

  Formation by thermal treatments (formation by plasma treatment H10P14/6319) · CPC title

• H10P14/6319

  Formation by plasma treatments, e.g. plasma oxidation of the substrate · CPC title