US 5,672,091 AGranted

Polishing apparatus having endpoint detection device

AssigneeEbara Corporation

InventorsTsutomu Takahashi, Keiichi Tohyama, Tamami Takahashi

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Abstract

A polishing apparatus has an automated endpoint detection device to determine if an endpoint of polishing has been reached without removing the wafer from a top ring of the polishing apparatus. When a pre-determined inspection time is reached in a process of polishing, the wafer is moved laterally along the turntable and the current surface condition of the wafer is determined by comparing the current surface condition with an initial surface condition, having an oxide film for example, determined from surface reflection measurement data carried out opto-electronically on the wafer before polishing. The endpoint detection device can be used to remove the surface oxide film so that the apex of the underlying device elements are just exposed. By eliminating the need for removing the wafer from the top ring for inspection, the cost of handling the wafer for polishing is reduced significantly, and enables reduction in the cost of manufactured devices. The endpoint determination device is applicable to any type of flat objects, such as LCD panels, requiring a high degree of polishing precision.

Claims12

Dependent claims

A polishing apparatus having a turntable, top ring means for pressing an object to be polished onto said turntable during polishing of a surface of the object, and an endpoint detection means for detecting an endpoint for stopping polishing of the surface of the object, said endpoint detection means comprising:

beam emitting means for projecting light beams onto an exposed portion of the surface of the object being held by said top ring means;
beam receiving means for receiving reflected beams reflected from the exposed portion of the surface;
and
endpoint judging means for determining a current surface condition of the surface from analysis of said reflected beams, said endpoint judging means comprising an electrical amplifier for amplifying analogue electrical signals received by said beam receiving means, analogue signal filtering means for filtering noise from the thus amplified analogue electrical signals, analogue-to-digital conversion means for converting said amplified analogue electrical signals to digital signals of surface data, computing means for computing an absolute value of a difference between an initial surface data of the surface in an initial unpolished state and current surface data and for comparing said absolute value with a predetermined threshold value to obtain comparison data, and controlling means for controlling operation of said polishing apparatus based on said comparison data.

1 more element

beam emitting means for projecting light beams onto an exposed portion of the object being held by said top ring means, said beam emitting means comprising a plurality of emitter elements disposed at a common distance from the surface;
beam receiving means for receiving reflected beams reflected from the exposed portion of the surface, said beam receiving means comprising a plurality of receiver elements, corresponding said plurality of emitter elements and disposed at a common distance from the surface;
and
endpoint judging means for determining a current surface condition of the surface from analysis of said reflected beams, said endpoint judging means comprising computing means for computing an added value or an averaged value of current surface data corresponding to added or averaged intensity of said reflected beams.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 08/577,536Filed 22 Dec 1995
Priority: JP 6-33642222 Dec 1994
Granted: 30 Sep 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

B24B 37/013
Control means for lapping machines or devices: devices or means for detecting lapping completion
B24B 49/02
Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring…
B24B 49/12
Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring…
B24B
Machines, devices, or processes for grinding or polishing