Automatic chemical and mechanical polishing system for semiconductor wafers

• US 5,643,044 A
• Filed: 11/01/1994
• Issued: 07/01/1997
• Est. Priority Date: 11/01/1994
• Status: Expired due to Fees

• Current Assignee: Douglas E. Lund
• Original Assignee: Douglas E. Lund
• Inventors: Lund, Douglas E.
• Primary Examiner(s): Rose, Robert A.
• Assistant Examiner(s): NGUYEN, GEORGE BINH MINH
• Application Number:
  US08/333,036
• Time in Patent Office: 973 Days
• Field of Search: 451/5, 451/6, 451/63, 451/168, 451/173, 451/296, 451/246, 451/388, 451/365, 451/385, 451/287, 451/291, 451/289, 451/307, 451/41
• US Class Current: 451/5
• CPC Class Codes: B24B 21/00 Machines or devices using grinding or polishing belts for sharpening cutting edges of tools B24B3/00; portable belt-grinding machines B24B23/06; Accessories therefor
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: B24B 37/105 the workpieces or work carriers being actively moved by a drive, e.g. in a combined rotary and translatory movement
• CPC Class Codes: B24B 49/12 involving optical means

Abstract

A system and method for chemically and mechanically polishing a semiconductor wafer having a substrate and a surface film. A wafer mounting device, which may include a vacuum chuck, holds the semiconductor wafer without requiring that the wafer have a central aperture. The mounting device and wafer are moved with an orbit-within-an-orbit motion while a tape transport mechanism applies an abrasive polishing tape to the surface film of the moving wafer to polish one surface of the wafer to a flatness of less than two microns. The system determines the thickness of the wafer surface film during the polishing process with a real time measurement device such as an ellipsometer, or by determining a work-performed factor and calculating an estimated film thickness from the work-performed factor. Finally, the system automatically controls the polishing process to stop polishing the semiconductor wafer when the wafer surface film achieves a predefined planarization.

Claims

1. A method of polishing a semiconductor wafer having a substrate and a surface film, said method comprising the steps of:

holding said semiconductor wafer without requiring that said wafer have a central aperture;

polishing one surface of said wafer to a microscopically smooth surface;

determining the thickness of said surface film, in real time, while polishing said wafer; and

automatically controlling said polishing step with a control computer, said automatic controlling step including the steps of;

providing measurements of said surface film thickness to said control computer in real time; and

stopping said polishing step when the thickness of said surface film, averaged over the entire surface of said wafer, achieves a predefined value.

2. The method of polishing a semiconductor wafer of claim 1 wherein said step of holding said semiconductor wafer without requiring that said wafer have a central aperture includes holding said wafer with a vacuum chuck.

3. The method of polishing a semiconductor wafer of claim 2 wherein said step of polishing one surface of said wafer to a microscopically smooth surface includes:

mounting said wafer on a mounting mechanism;

moving said mounting mechanism in an orbit-within-an-orbit motion; and

applying an abrasive polishing tape to the surface film of the moving wafer with a tape transport mechanism.

4. The method of polishing a semiconductor wafer of claim 3 wherein said step of mounting said wafer on a mounting mechanism includes supplying a negative pressure of approximately 10 Torr to said vacuum chuck with a rotary vacuum mechanism.

5. The method of polishing a semiconductor wafer of claim 4 wherein said step of determining the thickness of said surface film, in real time, includes measuring the thickness of said surface film with an ellipsometer.

6. The method of polishing a semiconductor wafer of claim 1 wherein said step of polishing one surface of said wafer to a microscopically smooth surface includes:

mounting said wafer on a mounting mechanism;

moving said mounting mechanism in an orbit-within-an-orbit motion; and

applying an abrasive polishing tape to the surface film of the moving wafer with a tape transport mechanism.

7. The method of polishing a semiconductor wafer of claim 1 wherein said step of mounting said wafer on a mounting mechanism includes supplying a negative pressure of approximately 10 Torr to said vacuum chuck with a rotary vacuum mechanism.

8. The method of polishing a semiconductor wafer of claim 1 wherein said step of determining the thickness of said surface film, in real time, includes measuring the thickness of said surface film with an ellipsometer.