Methods of downstream microwave photoresist removal and via clean, particularly following Stop-On TiN etching

• US 7,157,375 B2
• Filed: 08/25/2004
• Issued: 01/02/2007
• Est. Priority Date: 08/25/2004
• Status: Expired due to Fees

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: Hinckley, Kelly, Murphey, Paul B., Oman, Daniel M., Wheeler, Paul Edward, Campbell, Timothy Scott
• Primary Examiner(s): Norton; Nadine
• Assistant Examiner(s): GEORGE, PATRICIA ANN
• Application Number:
  US10/925,555
• Publication Number:
  US 20060043062A1
• Time in Patent Office: 860 Days
• Field of Search: 438/689
• US Class Current: 438/689
• CPC Class Codes: G03F 7/427 using plasma means only
• CPC Class Codes: H01L 21/02063 the processing being the formation of vias or contact holes
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31138 by dry-etching

Abstract

A process for photoresist layer removal from a semiconductor wafer comprises exposing at relatively high temperature the wafer to an RIE-free microwave-energy-generated plasma of a primary gas mixture, the exposing causing photoresist removal such as by ashing. The method also comprises determining an endpoint to the removal by a determined change in the visible light emanating from a chamber containing the wafer.

A multi-step process of the present invention comprises the above method and a preliminary RIE-free microwave-energy-generated plasma that solubilizes polymer on walls of vias of the wafer. This multi-step process also comprises, following the exposing step, a cooling step, a cooling step with a temperature check, and a deglazing step. The deglazing step also uses an RIE-free microwave-energy-generated plasma. Specific gas mixtures for the respective plasmas are exemplified. Other embodiments of methods of the present invention are comprised of less steps, or a consolidation of such steps.

Claims

1. A process for removal of a photoresist layer from a semiconductor wafer in a chamber, comprising:

a. creating a microwave-energy-generated plasma with no RIE and at a standard temperature, with a first gas mixture comprising oxygen and a fluorine-containing gas, the amount of the fluorine-containing gas sufficient to convert a polymer on side walls of etched features in the wafer to a water soluble form, and contacting the wafer with the microwave-energy-generated plasma;

b. subsequent to creating, stripping the photoresist layer from the wafer using a microwave-energy-generated plasma of a second gas mixture comprising oxygen and a nitrogen species, and no fluorine-containing gas and without an RIE process and at a relatively high temperature;

c. determining an endpoint to the stripping of the photoresist layer by a determined change in visible light in the chamber; and

d. removing the converted polymer with water.

2. The process of claim 1 wherein the stripping comprises creating the microwave-energy-generated plasma in a compartment separate from the wafer, and conveying the microwave-energy-generated plasma to the wafer.

3. The process of claim 1 wherein the change in visible light is a change in light intensity.

4. The process of claim 1 wherein the change in visible light is a change in color.

5. The process of claim 1 wherein the wafer comprises a TiN layer and additionally comprising, after the steps of claim 1, deglazing the TiN layer.

6. The process of claim 5 wherein the deglazing comprises creating a deglazing microwave-energy-generated plasma with no RIE process, with a deglazing gas mixture comprising oxygen and a fluorine-containing gas, and contacting the wafer with the deglazing microwave-energy-generated plasma.

7. A multi-step fabrication method for a semiconductor wafer comprising:

a. contacting the wafer with a first microwave-generated plasma formed with a first gas mixture comprising oxygen and a fluorine-containing species, the wafer between about 30 and about 50 degrees Celsius, the first microwave-generated plasma being effective to convert the polymer on side walls of etched features in the wafer to a water soluble form;

b. contacting the wafer with a second microwave-generated plasma formed with a second gas mixture comprising oxygen and a nitrogen species, and no fluorine-containing gas, heating the wafer to about 250 degrees Celsius, the second microwave-generated plasma being effective to remove a photoresist layer from the wafer;

c. cooling the wafer;

d. contacting the wafer with a third microwave-generated plasma formed with a third gas mixture comprising oxygen, a nitrogen species, and a fluorine-containing species, the wafer less than about 135 degrees Celsius, and the third microwave-generated plasma being effective to remove oxides from metal surfaces on the wafer; and

e. removing the converted polymer with water.

8. The method of claim 7, additionally comprising detecting the temperature before step “

d”

to assure the wafer is less than about 135 degrees Celsius.

9. The method of claim 7, the heating comprising applying heat from a lamp heater disposed above the wafer.

10. The method of claim 7, the fluorine-containing species of the first gas mixture comprising greater than about 4.0 percent and less than about 10.0 percent of the first gas mixture.