Method providing an improved bi-layer photoresist pattern

• US 7,049,052 B2
• Filed: 05/09/2003
• Issued: 05/23/2006
• Est. Priority Date: 05/09/2003
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Sadjadi, S. M. Reza, Zhu, Helen H., Tang, Kuo-Lung, Xiao, Hanzhong
• Primary Examiner(s): Barreca, Nicole
• Application Number:
  US10/435,130
• Publication Number:
  US 20040224264A1
• Time in Patent Office: 1,110 Days
• Field of Search: 430/313, 430/316, 430/317, 430/322, 430/323, 216/51, 216/72, 216/79
• US Class Current: 430/323
• CPC Class Codes: H01L 21/0273 characterised by the treatment of photoresist layers
• CPC Class Codes: H01L 21/0332 characterised by their composition, e.g. multilayer masks, materials
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks

Abstract

A method for etching a feature in a layer is provided. An underlayer of a polymer material is formed over the layer. A top image layer is formed over the underlayer. The top image layer is exposed to patterned radiation. A pattern is developed in the top image layer. The pattern is transferred from the top image layer to the underlayer with a reducing dry etch. The layer is etched through the underlayer, where the top image layer is completely removed and the underlayer is used as a pattern mask during the etching the layer to transfer the pattern from the underlayer to the layer.

Claims

1. A method for etching a feature in a layer, comprising:

forming an underlayer of a polymer material over the layer;

forming a top image layer over the underlayer;

exposing the top image layer to patterned radiation;

developing a pattern in the top image layer;

hardening the pattern in the top image layer, wherein hardening the pattern in the top image layer, comprises exposing the top image layer to a oxygen containing plasma and etching less than 25% of the underlayer;

transferring the pattern from the top image layer to the underlayer with a reducing dry etch; and

etching the layer through the underlayer, where the top image layer is completely removed and the underlayer is used as a pattern mask during the etching the layer to transfer the pattern from the underlayer to the layer.

2. The method, as recited in claim 1, wherein the transferring the pattern from the top image layer to the underlayer, comprises:

providing a reducing gas;

generating a plasma from the reducing gas; and

etching the underlayer with the plasma from the reducing gas.

3. The method, as recited in claim 2, wherein the reducing gas is oxygen free.

4. The method, as recited in claim 3, wherein the reducing gas provides a nitrogen species and hydrogen species in the plasma generated from the reducing gas.

5. The method, as recited in claim 4, wherein the reducing gas further comprises a hydrocarbon.

6. The method, as recited in claim 5, wherein the reducing gas further comprises a hydrofluorocarbon.

7. The method, as recited in claim 4, wherein the reducing gas further comprises a hydrofluorocarbon.

8. The method, as recited in claim 1, further comprising removing the underlayer.

9. The method, as recited in claim 1, further comprising removing the underlayer.

10. A method for etching a feature in a layer, comprising:

forming an underlayer of a polymer material over the layer;

forming a top image layer over the underlayer;

exposing the top image layer to patterned radiation;

developing a pattern in the top image layer;

hardening the top image layer,

transferring the pattern from the top image layer to the underlayer, comprising

providing a reducing gas, which is oxygen free;

generating a plasma from the oxygen free reducing gas; and

etching the underlayer with the plasma from the oxygen free reducing gas; and

etching the layer through the underlayer, where the top image layer is completely removed and the underlayer is used as a pattern mask during the etching the layer to transfer the pattern from the underlayer to the layer.

11. The method, as recited in claim 10, wherein the top image layer has a higher concentration of silicon than the underlayer.

12. The method, as recited in claim 10, wherein the oxygen containing plasma is generated from an oxygen containing gas where a flow of oxygen is more than 4% of total gas flow.

13. The method, as recited in claim 10, wherein the reducing gas provides a nitrogen species and hydrogen species in the plasma generated from the reducing gas.

14. The method, as recited in claim 13, wherein the reducing gas further comprises a hydrocarbon.

15. The method, as recited in claim 14, wherein the reducing gas further comprises a hydrofluorocarbon.