US 6,257,953 B1Granted

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 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 an end-point 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 electrical-conductive elements located on the surface of the pad and connected via contact pins embedded in the material of the platen to respective resistance measurement unit. A second group of sensing elements is represented by capacitance probes having conductive elements on the surface of the pad and connected via contacts embedded in the body of the platen to the capacitance measurement unit. A third group of sensing devices is represented by acoustic emission sensors built on various levels into components of the rotating head. A fourth group of sensing devices is represented by a pair of force/torque sensors connected with drive shafts of the rotating head and the platen, respectively, and intended for direct measurement of torques of respective shafts 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.

Claims21

Dependent claims

An apparatus for controlled polishing, comprising:

a rotating platen with a replaceable resilient pad removably attached to the top of said rotating platen, said replaceable pad having a working surface opposed to said rotating platen, said rotating platen having an axis of rotation;
a rotating head having an axis of rotation and being capable of performing rotary motions and radial movements with respect to said platen, said axis of rotation of said rotating head being offset with respect to said axis of rotation of said platen, said rotating head having means for supporting an object to be treated, said object having a front surface to be polished and at least a portion with properties changed as a result of polishing;
sensing means for 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:
first mechanical sensing means associated with said rotating platen and generating first data signal;
second mechanical sensing means associated with said rotating head and generating second data signal;
a plurality of groups of acoustical sensing means built into said rotating head and generating third data signal;
a plurality of groups of electrical sensing means built into said platen and said pad, generating fourth data signal and arranged circumferentially in at least one circular row concentrically with respect to said axis of rotation of said platen;
and
measuring means for acquiring, measuring and conditioning said data signals obtained from said sensing means, said measuring means having a first friction measurement unit, a second friction measurement unit, a resistance measurement unit, a capacitance measurement unit, and an acoustic measurement unit;
control means for combined control of said polishing;
and
connecting means for connecting said measuring means to said control means, said connecting means comprising a first connecting unit and a second connecting unit.

9 more elements

A method for controlling a process of polishing an object having a front surface to be polished, with at least a part of said object having properties which change during said process, said method comprising the steps of:

providing a polishing apparatus comprising a rotating platen having a drive shaft and replaceable resilient pad, a rotating head having a drive shaft and capable of performing rotary motions and radial movements with respect to said platen, said rotating head having means for supporting an object to be treated, said object having a front surface to be polished and at least a portion with properties changed as a result of polishing, and sensing means for combined sensing of changes that occur on said front surface of said object being polished during said process of polishing, said sensing means generating data signals and comprising a plurality of groups of mechanical sensing means, electrical resistance sensing means, electrical capacitance sensing means, acoustical sensing means, a measuring means, a control means, and a connecting means, said platen has an axis of rotation;
arranging at least one group of said mechanical sensing means in association with said drive shaft of said rotating platen;
arranging at least one group of said mechanical sensing means in association with said drive shaft of said rotating head;
arranging said groups of said electrical resistance sensing means and of said electrical capacitance sensing means circumferentially in at least one circular row concentrically with said axis of rotation of said platen;
arranging said acoustical sensing means in said rotating head;
polishing said object in said process of polishing by means of said apparatus;
sensing changes of said properties during said process of polishing simultaneously by means of said plurality of groups of electrical resistance sensing means, electrical capacitance sensing means, mechanical sensing means, and acoustical sensing means;
and
measuring and processing said data signals obtained from said plurality of groups of electrical resistance sensing means, electrical capacitance sensing means, mechanical sensing means, and acoustical sensing means by said measuring means;
and
controlling said process of polishing in response to said step of measuring and processing.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/669,214Filed 25 Sep 2000
Granted: 10 Jul 2001
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

B24B 37/013
Control means for lapping machines or devices: devices or means for detecting lapping completion
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 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…