Multiple etch method for fabricating spacer layers

• US 6,764,911 B2
• Filed: 05/10/2002
• Issued: 07/20/2004
• Est. Priority Date: 05/10/2002
• Status: Expired due to Fees

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Hsu, Jw-Wang, Kuo, Mei-Ru, Peng, Baw-Ching, Tao, Hun-Jan, Tsai, Ming-Huan
• Primary Examiner(s): NGUYEN, THANH T
• Application Number:
  US10/143,227
• Publication Number:
  US 20030211697A1
• Time in Patent Office: 802 Days
• Field of Search: 438/299-307, 438/595-596
• US Class Current: 438/303
• CPC Class Codes: H01L 29/6653 using the removal of at least part of spacer, e.g. disposable spacer
• CPC Class Codes: H01L 29/6656 using multiple spacer layers, e.g. multiple sidewall spacers
• CPC Class Codes: H01L 29/6659 with both lightly doped source and drain extensions and source and drain self-aligned to the sides of the gate, e.g. lightly doped drain [LDD] MOSFET, double diffused drain [DDD] MOSFET
• CPC Class Codes: H01L 29/7833 with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's for thin film transistors H01L29/78618

Abstract

Within a method for forming a spacer layer from a second layer formed of a second material laminated upon a first layer formed of a first material, in turn formed over a topographic feature, there is employed a three step etch method. The three step etch method employs: (1) a first etch method having a first enhanced etch selectivity for the second material with respect to the first material; (2) a second etch method having a second substantially neutral etch selectivity for the second material with respect to the first material; and (3) a third etch method having a third enhanced etch selectivity for the first material with respect to the second material. In accord with the three step etch method, the spacer layer is fabricated with enhanced dimensional control.

Claims

1. A method for fabricating a spacer layer comprising:

providing a substrate having formed thereover a topographic feature;

forming over the substrate including the topographic feature a first layer of a first material having formed thereupon a second layer of a second material;

etching, while employing a first etch method having a first enhanced etch selectivity for the second material with respect to the first material, the second layer to form therefrom a second spacer layer formed upon the first layer;

etching, while employing a second etch method having a second substantially neutral etch selectivity for the second material with respect to the first material, the second spacer layer and first layer to form therefrom an etched second spacer layer formed upon a partially etched first layer; and

etching, while employing a third etch method having a third enhanced etch selectivity for the first material with respect to the second material, the partially etched first layer to form a first spacer layer having formed thereupon the etched second spacer layer wherein outer side surface of said first spacer and said second spacer are aligned.

2. The method of claim 1 wherein:

the first enhanced etch selectivity for the second material with respect to the first material is greater than about 5;

1;

the second substantially neutral etch selectivity for the second material with respect to the first material is from about 2;

1 to about 0.5;

1; and

the third enhanced etch selectivity for the first material with respect to the second material is greater than about 5;

1.

3. The method of claim 1 wherein the substrate is employed within a microelectronic fabrication selected from the group consisting of integrated circuit microelectronic fabrications, ceramic substrate microelectronic fabrications, solar cell optoelectronic microelectronic fabrications, sensor image array optoelectronic microelectronic fabrications and display image array optoelectronic microelectronic fabrications.

4. The method of claim 1 wherein each of the substrate, the topographic feature, the first layer and the second layer is independently formed from a material selected from the group consisting of conductor materials, semiconductor materials and dielectric materials.

5. The method of claim 1 wherein the first layer is formed to a thickness of from about 50 to about 1000 angstroms.

6. The method of claim 1 wherein the second layer is formed to a thickness of from about 50 to about 1500 angstroms.

7. The method of claim 1 wherein each of the first etch method, the second etch method and the third etch method is an anisotropic etch method.

8. The method of claim 1 wherein each of the first etch method, the second etch method and the third etch method is an isotropic etch method.

9. A method for fabricating a spacer layer comprising:

providing a semiconductor substrate having formed thereover a topographic feature;

forming over the semiconductor substrate including the topographic feature a first layer of a first material having formed thereupon a second layer of a second material;

etching, while employing a first etch method having a first enhanced etch selectivity for the second material with respect to the first material, the second layer to form therefrom a second spacer layer formed upon the first layer;

etching, while employing a second etch method having a second substantially neutral etch selectivity for the second material with respect to the first material, the second spacer layer and first layer to form therefrom an etched second spacer layer formed upon a partially etched first layer; and

etching, while employing a third etch method having a third enhanced etch selectivity for the first material with respect to the second material, the partially etched first layer to form a first spacer layer having formed thereupon the etched second spacer layer wherein outer side surface of said first spacer and said second spacer are aligned.

10. The method of claim 9 wherein:

the first enhanced etch selectivity for the second material with respect to the first material is greater than about 5;

1;

the second substantially neutral etch selectivity for the second material with respect to the first material is from about 2;

1 to about 0.5;

1; and

the third enhanced etch selectivity for the first material with respect to the second material is greater than about 5;

1.

11. The method of claim 9 wherein the first layer is formed to a thickness of from about 50 to about 1000 angstroms.

12. The method of claim 9 wherein the second layer is formed to a thickness of from about 50 to about 1500 angstroms.

13. The method of claim 9 wherein each of the first etch method, the second etch method and the third etch method is an anisotropic etch method.

14. The method of claim 9 wherein each of the first etch method, the second etch method and the third etch method is an isotropic etch method.

15. The method of claim 9 wherein the first material and the second material are separate materials selected from the group consisting of silicon oxide materials, silicon nitride materials and silicon oxynitride materials.

16. The method of claim 9 wherein the topographic feature is a patterned conductor layer.