System for real-time control of semiconductor wafer polishing including optical monitoring

• US 5,658,183 A
• Filed: 10/24/1995
• Issued: 08/19/1997
• Est. Priority Date: 08/25/1993
• Status: Expired due to Term

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Sandhu, Gurtej S., Doan, Trung Tri
• Primary Examiner(s): Rose, Robert A.
• Assistant Examiner(s): NGUYEN, GEORGE BINH MINH
• Application Number:
  US08/547,944
• Time in Patent Office: 665 Days
• Field of Search: 451/5, 451/6, 451/7, 451/8, 451/10, 451/21, 451/41, 451/42, 451/60, 451/63, 451/287, 451/288, 451/289, 356/381, 356/382, 250/559.27, 250/559.28
• US Class Current: 451/5
• CPC Class Codes: B23Q 15/013 Control or regulation of feed movement B23Q15/12 takes precedence
• CPC Class Codes: B23Q 15/12 Adaptive control, i.e. adjusting itself to have a performance which is optimum according to a preassigned criterion
• CPC Class Codes: B24B 13/015 of television picture tube viewing panels, headlight reflectors or the like
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: B24B 37/015 Temperature control
• CPC Class Codes: B24B 37/107 in a rotary movement only, about an axis being stationary during lapping
• CPC Class Codes: B24B 37/12 Lapping plates for working plane surfaces
• CPC Class Codes: B24B 37/205 provided with a window for inspecting the surface of the work being lapped
• CPC Class Codes: B24B 49/003 involving acoustic means
• CPC Class Codes: B24B 49/02 according to the instantaneous size and required size of the workpiece acted upon, the measuring or gauging being continuous or intermittent B24B49/12 takes precedence
• CPC Class Codes: B24B 49/04 involving measurement of the workpiece at the place of grinding during grinding operation
• CPC Class Codes: B24B 49/10 involving electrical means B24B49/02, B24B49/08 take precedence
• CPC Class Codes: B24B 49/12 involving optical means
• CPC Class Codes: B24B 57/02 for feeding of fluid, sprayed, pulverised, or liquefied grinding, polishing or lapping agents
• CPC Class Codes: G05B 19/404 characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia G05B19/19, G05B19/41 take precedence
• CPC Class Codes: G05B 2219/34403 RTI real time, kernel, processing
• CPC Class Codes: G05B 2219/37398 Thickness
• CPC Class Codes: G05B 2219/37602 Material removal rate
• CPC Class Codes: G05B 2219/45026 Circuit board, pcb
• CPC Class Codes: G05B 2219/45199 Polish
• CPC Class Codes: G05B 2219/45232 : CMP chemical mechanical polishing of wafer
• CPC Class Codes: G05B 2219/49052 : Accessory, coolant
• CPC Class Codes: G05B 2219/49057 : Controlling temperature of workpiece, tool, probe holder

Abstract

A system for polishing a semiconductor wafer, the system comprising a wafer polishing assembly for polishing a face of a semiconductor wafer at a polishing rate and a polishing uniformity, the wafer polishing assembly including a platen subassembly defining a polishing area, a slurry supply system delivering a slurry to the polishing area, and a polishing head selectively supporting a semiconductor wafer and holding a face of the semiconductor wafer in contact with the platen subassembly; and an optical measurement system measuring film thickness at multiple different locations on the wafer face while the wafer is under a liquid, wherein drying of the wafer is avoided while the measurements are taken.

Claims

1. A system for polishing a semiconductor wafer, the system comprising:

a wafer polishing assembly for polishing a face of a semiconductor wafer at a polishing rate and a polishing uniformity, the wafer polishing assembly including a platen subassembly defining a polishing area, a slurry supply system delivering a slurry to the polishing area, and a polishing head selectively supporting a semiconductor wafer and holding a face of the semiconductor wafer in contact with the platen subassembly;

an endpoint detector operating on the wafer to determine whether polishing of the wafer is complete, the endpoint detector having an optical measurement system including an optical window spaced apart from the platen subassembly, including a liquid filled, wafer receiving area, on one side of the optical window, which selectively receives the wafer, and including optics on the other side of the window, and movable relative to the wafer receiving area, which scan the wafer face while the wafer face remains stationary, the optical measurement system measuring film thickness at multiple different locations on the wafer face while the wafer face is in contact with a liquid, wherein drying of the wafer is impeded while the film thickness measurements are taken; and

a robot selectively moving the wafer between the platen subassembly and the wafer receiving area.

2. A system for polishing a semiconductor wafer comprising:

a wafer polishing assembly for polishing a face of a semiconductor wafer at a polishing rate and a polishing uniformity, the wafer polishing assembly including a platen, a polishing head which supports the semiconductor wafer, and a polishing head displacement mechanism which moves the polishing head and wafer across the platen along an adjustable polishing path, the wafer polishing assembly having a plurality of controllable operational parameters, including polishing path, that upon variation change the polishing rate and polishing uniformity;

a controller operably coupled to the wafer polishing assembly for monitoring and managing in situ at least one of the operational parameters of the wafer polishing assembly;

a processor operably coupled to the controller for determining a set of desired operational parameters based on the monitored operational parameters and outputting control information indicative of the desired operational parameters to the controller, the controller adjusting in situ at least one of the operational parameters of the wafer polishing assembly in response to the control information from the processor to effectuate a new polishing rate and a new polishing uniformity as the wafer polishing assembly continues to polish the face of the semiconductor wafer;

a detector operating on the wafer and communicating with the processor to determine whether polishing of the wafer is complete, the detector including an optical measurement system including a wafer receiving area spaced apart from the platen and measuring film thickness at multiple different locations on the wafer face while the wafer is under a liquid, the optical measurement system including movable optics which scan the wafer face while the wafer face remains stationary and;

a robot selectively moving the wafer between the platen and the wafer receiving area.

3. A system in accordance with claim 2 wherein the optical measurement system includes a pattern recognition system.

4. A system in accordance with claim 2 wherein the optical measurement system comprises an optical window, and wherein the wafer receiving area is liquid filled and is located above the window, and wherein the optics are located below the window.