Method and apparatus for endpoint detection in a chemical/mechanical process for polishing a substrate

• US 5,595,526 A
• Filed: 11/30/1994
• Issued: 01/21/1997
• Est. Priority Date: 11/30/1994
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Intel Corporation
• Inventors: Yau, Leopoldo D., Fischer, Paul B.
• Primary Examiner(s): Rose, Robert A.
• Application Number:
  US08/347,813
• Time in Patent Office: 783 Days
• Field of Search: 451/8, 451/10, 451/11, 451/41, 451/9, 451/5, 451/21, 451/287, 451/290
• US Class Current: 451/8
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: B24B 37/042 operating processes therefor

Abstract

A method for polishing the surface of a substrate that overcomes the problems inherent in the prior art. During the polishing of a substrate, a quantity is calculated which is approximately proportional to a share of the total energy the polisher is consuming. Once this calculated quantity reaches a predetermined amount, it is detected.

Claims

1. In a chemical/mechanical process for polishing a substrate, a method of endpoint detection comprising the steps of:

(a) determining a target amount of energy needed by a polishing apparatus to produce a desired polishing result on the substrate;

(b) providing an energy source to the polishing apparatus to commence the chemical/mechanical process;

(c) calculating a total energy consumption by integrating over time an electrical parameter of the polishing apparatus that is approximately proportional to an instantaneous power consumed by the polishing apparatus; and

(d) stopping the chemical/mechanical process when the total energy consumption equal the target amount of energy.

2. The method of claim 1 wherein the electrical parameter comprises a current supplied to a motor of the polishing apparatus.

3. The method of claim 1 wherein the electrical parameter comprises a voltage supplied to a motor of the polishing apparatus that utilizes a constant current source.

4. The method of claim 1 wherein step (c) comprises the steps of:

performing measurements of the electrical parameter in a time period;

integrating the measurements over the time period to produce a first energy quantity;

subtracting an overhead energy contribution from the first energy quantity, resulting in the total energy consumption.

5. The method of claim 4 wherein the overhead energy contribution includes a chemical etch component.

6. The method of claim 1 wherein the desired polishing result is a planarized surface of a dielectric film disposed over a layer of interconnects.

7. In a chemical/mechanical process for polishing a semiconductor substrate, a method of endpoint detection comprising the steps of:

(a) determining a target amount of energy needed by a polishing apparatus to produce a desired polishing result on the semiconductor substrate;

(b) energizing a plurality of motors in the polishing apparatus to begin the chemical/mechanical process;

(c) repeatedly performing parametric measurements to calculate a total energy consumed by the motors over a time period;

(d) stopping the chemical/mechanical process when the total energy consumed by the motors over the time period equals the target amount of energy.

8. The method of claim 7 wherein the plurality of motors includes a first motor that rotates a polishing surface, and a second motor that rotates the semiconductor substrate against the polishing surface.

9. The method of claim 8 wherein step (c) includes the step of:

measuring a first current supplied to the first motor.

10. The method of claim 9 wherein step (c) further includes the step of:

measuring a second current supplied to the second motor.

11. The method of claim 10 wherein step (c) further includes the step of:

integrating the first and second currents over the time period.

12. The method of claim 10 wherein step (c) further includes the step of:

subtracting an overhead energy contribution to the total energy consumed.

13. The method of claim 12 wherein the overhead energy contribution includes a chemical etch component.

14. The method of claim 7 wherein the desired polishing result is a planarized surface of a dielectric film disposed over a layer of interconnects.