US 6,494,765 B2Granted

Method and apparatus for controlled polishing

AssigneeCenter for Tribology, Inc.

InventorsNorm Gitis, Michael Vinogradov

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Abstract

An apparatus for controlling a polishing process, in particular for detecting an end point of the polishing process, comprising a rotating or orbiting platen with a pad, a rotating head that supports an object to be treated, e.g., a semiconductor wafer, and performs radial movements with respect to the platen, and a polishing process control system comprising a plurality of groups of various sensing devices for detecting an end point of the process. In the illustrated embodiment one group of the sensing devices is a group of high-frequency acoustic emission sensors built on various levels into components of the rotating head. Another group of sensing devices is represented by force/torque sensors connected with various elements of the rotating head and the platen, respectively, and intended for direct measurement of compression force and friction response (force or torque) between the head and the platen and a coefficient of friction between the wafer and the polishing pad. All groups of sensors work simultaneously and their measurement data is processed and analyzed by a control unit for obtaining accurate and reliable results.

Claims45

Dependent claims

An apparatus for controlled polishing an object having a surface to be polished in a polishing process, comprising:

a frame which has a base plate and at least one vertical column;
a vertical positioning means mounted on said at least one vertical column;
a first drive means for moving said vertical positioning means along said at least one vertical column with respect to said base plate;
a horizontal positioning means being capable of performing motions in a direction parallel to said base plate;
a second drive means for moving said horizontal positioning means in said direction parallel to said base plate;
a head having means for supporting an object to be treated, said head being capable of performing vertical, horizontal and rotary motions and having an axis of rotation, said object having a front surface to be polished;
a third drive means for rotating said head in respect to said axis;
a polishing module which is attachable to said base plate, has a platen with a polishing pad removably attached to the top of said platen and a polishing drive means for moving said platen with respect to said object, while maintaining them in contact, said polishing pad having a working surface opposed to said platen, said working surface being in parallel to said front surface of said object, said platen having a center;
sensing means for simultaneous combined sensing of changes that occur on said front surface of said object being polished during said polishing and for generating output data signals, said sensing means comprising:
compression sensing means for generating compression data signals corresponding to a force with which said object is pressed during polishing to said polishing pad;
friction sensing means for generating friction data signals corresponding to a friction force that occurs during polishing between said polishing pad and said object;
and
transducing means for acquiring, amplifying and conditioning said compression data signals obtained from said compression sensing means and said friction data signals obtained from said friction sensing means, said transducing means having a compression measurement unit and a friction measurement unit;
control means for combined processing said data signals and for combined controlling of said polishing process, comprising a processing unit and a display unit;
and
connecting means for connecting said transducing means to said control means.

13 more elements

A method for controlling a process of polishing an object having a front surface to be polished, said method comprising the steps of:

providing a polishing apparatus comprising a frame with a base plate, a head having means for supporting an object to be treated, said head being capable of performing rotary motions and having an axis of rotation, said object having a front surface to be polished, a polishing module which is attachable to said base plate and has a platen with a replaceable resilient pad having working surface, a sensing means for combined sensing of changes that occur between said front surface of said object being polished and said working surface of said resilient pad during said process of polishing, said sensing means generating output data signals and comprising a compression sensing means and a friction sensing means, a transducing means having a compression measurement unit and a friction measurement unit, a control means having a processing unit and a display unit and a connecting means;
bringing said front surface of said object in contact with said working surface of said pad;
polishing said object in said process of polishing by means of said apparatus;
sensing changes on said front surface of said object being polished during said process of polishing simultaneously by means of said compression sensing means and said friction sensing means;
measuring and combined processing said data signals obtained from said compression sensing means and friction sensing means;
computing predetermined parameters of said process of polishing based on said data signals by means of said processing unit;
comparing said predetermined parameters obtained in said step of computing with predefined optimized parameters of said process of polishing;
and
controlling said process of polishing in response to said steps of measuring and combined processing, computing, and comparing.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/859,062Filed 17 May 2001 · continuation in part
Priority: 25 Sep 2000
Published: US 2002/0037681 A128 Mar 2002
Granted: 17 Dec 2002
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

B24B 49/04
According to the instantaneous size and required size of the workpiece acted upon, the measuring or gauging being continuous or intermittent:…
B24B 37/013
Control means for lapping machines or devices: devices or means for detecting lapping completion
B24B 49/10
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…