Laser induced chemical etching of metals with excimer lasers

• US 4,490,211 A
• Filed: 01/24/1984
• Issued: 12/25/1984
• Est. Priority Date: 01/24/1984
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Chen, Lee, Mathad, Gangadhara S., Lankard, John R.
• Primary Examiner(s): Powell, William A.
• Application Number:
  US06/573,452
• Time in Patent Office: 336 Days
• Field of Search: 156/635, 156/638, 156/643, 156/646, 156/656, 156/664, 156/666, 156/345, 427/53.1, 219/121 L, 219/121 LH, 219/121 LJ, 219/121 FS, 219/121 LM
• US Class Current: 216/62
• CPC Class Codes: C23F 4/02 by evaporation
• CPC Class Codes: H05K 3/027 the conductive material being removed by irradiation, e.g. by photons, alpha or beta particles

Abstract

Disclosed is a method of etching a metallized substrate by excimer laser radiation. The substrate is exposed to a selected gas, e.g., a halogen gas, which spontaneously reacts with the metal forming a solid reaction product layer on the metal by a partial consumption of the metal. A beam of radiation from an excimer laser, e.g. XeF laser operating at a wavelength of 351 nm or XeCl laser at 308 nm or KrF laser at 248 nm or KrCl laser at 222 nm or ArF laser at 193 nm or F₂ laser at 157 nm, is applied to the reaction product in a desired pattern to vaporize the reaction product and thereby selectively etch the metal with a high resolution.

Claims

1. A method of radiation induced dry etching of a metallized substrate comprising the steps of:

(a) mounting the substrate in a reaction chamber;

(b) establishing a predetermined low pressure in the chamber;

(c) controllably introducing a selected gas into the chamber to form a solid reaction product with the metal by a partial consumption of the surface of said metal; and

(d) selectively removing the reaction product by applying a beam of excimer laser radiation and thereby selectively etching the metal.

2. The method as in claim 1 wherein said radiation is of a wavelength suitable for absorption by said reaction product.

3. The method as in claim 2 wherein said reaction product is removed by said radiation by thermal excitation and eventual vaporization.

4. The method as in claim 3 wherein said gas is halogen gas.

5. The method as in claim 4 wherein said gas is chlorine.

6. The method as in claim 5 wherein said metal is copper and said reaction product is copper chloride.

7. The method as in claim 5 wherein said metal is selected from a group consisting of chromium, titanium, aluminum, molybdenum, and stainless steel.

8. The method as in claim 6 or 7 wherein said excimer laser is selected from a group consisting of XeF laser operating at a wavelength of 351 nm, XeCl laser at 308 nm, KrF laser at 248 nm, KrCl laser at 222 nm, ArF laser at 193 nm and F₂ laser at 157 nm.

9. A method of radiation induced dry etching of a copper layer formed on a substrate comprising:

(a) reacting said copper layer with a halogen gas forming a solid copper halide reaction product layer thereon by at least a partial consumption of said copper layer; and

(b) selectively removing the copper halide, by vaporization, by applying, in a predetermined pattern, radiation from an excimer laser and thereby selectively etching the copper layer.

10. The method as in claim 9 wherein said excimer laser is selected from a group consisting of XeF laser operating at a wavelength of 351 nm, XeCl laser at 308 nm, KrF laser at 248 nm, KrCl laser at 222 nm, ArF laser at 193 nm and F₂ laser at 157 nm.