US 6,618,130 B2 · Method and apparatus for optical endpoint detection during chemical mechanical polishing

Abstract

A method for detecting during a planarization process the removal of a first layer of material overlying a workpiece is provided. Relative motion is effected between the first layer and a working surface to remove the first layer. A light having a spectrum of wavelengths is transmitted to the workpiece. The intensity for each of a plurality of reflected wavelengths of a reflected light reflected from the workpiece is measured to obtain a spectrum. The spectrum is a function of the plurality of reflective wavelengths. A spectrum reference value is calculated and a plurality of spectrum difference values are calculated by subtracting the spectrum reference value from the spectrum. An absolute value for each of the plurality of spectrum difference values that is a function of one of the plurality of reflected wavelengths that falls within a selected range of wavelengths is summed together to obtain a delta value. An endpoint parameter is calculated from the delta value.

Claims17

Dependent claims

A method for detecting, during a planarization process, the removal of a first layer of material overlying a workpiece said method comprising:

(a) causing relative motion between said first layer and a working surface to remove said first layer;
(b) during said causing relative motion, transmitting to said workpiece a light having a spectrum of wavelengths;
(c) measuring an intensity for each of a plurality of reflected wavelengths of a reflected light reflected from said workpiece to obtain a spectrum, wherein said spectrum is a function of said plurality of reflected wavelengths;
(d) calculating a reference spectrum;
(e) calculating a plurality of spectrum difference values by subtracting said reference spectrum from said spectrum, wherein each of said spectrum difference values is a function of one of said plurality of reflected wavelengths;
(f) selecting a range of wavelengths;
(g) summing together an absolute value for each of said plurality of spectrum difference values that is a function of one of said plurality of reflected wavelengths that falls within said range of wavelengths to obtain a delta value therefrom;
and
(h) calculating an endpoint parameter from the delta value.

6 more elements

An apparatus for detecting the removal of a first layer of material overlying a workpiece during a chemical mechanical planarization process, said apparatus comprising:

a light-illuminating assembly for transmitting light to the workpiece;
a light-receiving assembly for receiving a reflected light reflected from the workpiece during one of a plurality of scan cycles;
a processor operatively connected to said light-receiving assembly and configured to:
measure an intensity for each of a plurality of reflected wavelengths of said reflected light reflected from said workpiece during said one of a plurality of scan cycles to obtain a spectrum, wherein said spectrum is a function of said plurality of reflected wavelengths;
calculate a reference spectrum value;
calculate a plurality of spectrum difference values by subtracting said reference spectrum from said spectrum, wherein each of said spectrum difference values is a function of one of said plurality of reflected wavelengths;
sum together an absolute value of each of said plurality of spectrum difference values that is a function of one of said plurality of reflected wavelengths that falls within a selected range of wavelengths to obtain a delta value therefrom;
and
calculate an endpoint parameter from said delta value.

6 more elements

Dependencies are inferred from the claim text.

Method and apparatus for optical endpoint detection during chemical mechanical polishing

Life of this patent

Method and apparatus for optical endpoint detection during chemical mechanical polishing

Life of this patent

Abstract

Claims17