Masking for high temperature implants

Patent metadata

Field	Value
Publication number	US-9679776-B2
Application number	US-201514807377-A
Country	US
Kind code	B2
Filing date	Jul 23, 2015
Priority date	Jul 23, 2015
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A method for the selective implantation of a workpiece is disclosed. In place of conventional photoresist, a two layer structure is used. The first layer, referred to as the protective layer, is applied directly to the workpiece and protects the workpiece from harmful etching processes. Additionally, the protective layer has limited ability to stop ions from impacting the workpiece. The second layer, referred to as the blocking layer, which is formed on a portion of the protective layer, is used to block ions from impacting the underlying workpiece. Advantageously, the blocking layer may be selectively etched without affecting the protective layer. Additionally, the protective layer can be removed without affecting the underlying workpiece. Through the use of this two layer technique, high temperature selective implants may be performed on a variety of different semiconductor devices.

First claim

What is claimed is:

1. A method of processing a workpiece, comprising:
depositing a carbon-based protective layer on the workpiece, wherein the carbon-based protective layer is conformally deposited on the workpiece;
forming a blocking layer on a portion of the carbon-based protective layer, less than an entirety of the carbon-based protective layer, wherein the conformally deposited carbon-based protective layer is not affected by and remains intact after the forming of the blocking layer, wherein the forming comprises:
depositing the blocking layer on the carbon-based protective layer;
applying photoresist to a portion of the blocking layer;
removing a portion of the blocking layer not covered by the photoresist without affecting the carbon-based protective layer; and
removing the photoresist from the blocking layer;
directing ions toward the workpiece after forming the blocking layer while the conformally deposited carbon-based protective layer remains intact on the workpiece and after the photoresist has been removed, wherein ions pass through the carbon-based protective layer and implant the workpiece, but do not pass through the blocking layer;
removing the blocking layer after the directing; and
removing the carbon-based protective layer after the directing.

2. The method of claim 1 , wherein the ions pass through the carbon-based protective layer and implant the workpiece, but do not pass through the blocking layer.

3. The method of claim 1 , wherein the ions are implanted at an elevated temperature above 150° C.

4. The method of claim 1 , wherein the carbon-based protective layer comprises a carbon-based film having a thickness of 10 nm or less.

5. The method of claim 1 , wherein the blocking layer comprises a material selected from the group consisting of silicon dioxide, silicon nitride, germanium, amorphous silicon and polysilicon.

6. The method of claim 1 , wherein the blocking layer is removed without removing the carbon-based protective layer.

7. The method of claim 6 , wherein the blocking layer is removed using a dry etch process.

8. The method of claim 6 , wherein the blocking layer comprises germanium and the blocking layer is removed using hot deionized water.

9. The method of claim 1 , wherein the blocking layer is selectively etched to the carbon-based protective layer.

10. A method of processing a workpiece, comprising:
depositing a carbon-based protective layer on the workpiece, wherein the protective layer is conformally deposited on the workpiece;
depositing a blocking layer on the carbon-based protective layer;
applying photoresist to a portion of the blocking layer;
removing a portion of the blocking layer not covered by the photoresist using a dry etch process, wherein the protective layer is not affected by the removing of the portion of the blocking layer;
removing the photoresist from the blocking layer using a hydrogen plasma strip such that the conformally deposited protective layer remains intact;
directing ions toward the workpiece after removing the photoresist and while the conformally deposited protective layer remains intact on the workpiece, wherein the ions pass through the carbon-based protective layer and implant the workpiece, but do not pass through the blocking layer;
removing the blocking layer using the dry etch process after the directing; and
removing the carbon-based protective layer from the workpiece using a sulphuric peroxide mixture after removing the blocking layer.

11. The method of claim 10 , wherein the blocking layer comprises silicon dioxide or silicon nitride, and the dry etch process uses a CHF 3 /CF 4 dry etch chemistry.

12. The method of claim 10 , wherein the blocking layer comprises silicon nitride, and the dry etch process uses a SF 6 dry etch chemistry.

13. The method of claim 10 , wherein the blocking layer comprises amorphous silicon or polysilicon, and the dry etch process uses a HBr dry etch chemistry.

14. The method of claim 10 , wherein the ions are implanted at an elevated temperature above 150° C.

15. The method of claim 10 , wherein the carbon-based protective layer is deposited using chemical vapor deposition.

16. The method of claim 10 , wherein no photoresist is present on the blocking layer during the directing.

17. The method of claim 1 , wherein the carbon-based protective layer is deposited using chemical vapor deposition.

18. The method of claim 1 , wherein no photoresist is present on the blocking layer during the directing.

Assignees

• Varian Semiconductor Equipment Ass Inc

Inventors

• Waite Andrew M
• Variam Naushad

Classifications

• H10P50/692

  characterised by their composition, e.g. multilayer masks or materials · CPC title

• H10P50/283

  by chemical means · CPC title

• H10P14/69433

  the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz · CPC title

• H10P14/69215

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

• H10P14/6902

  composed of carbon, e.g. alpha-C, diamond or hydrogen doped carbon · CPC title