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US 6,632,321 B2Granted
Method and apparatus for monitoring and controlling wafer fabrication process
AssigneeApplied Materials, Inc.
InventorsThorsten Lill, David Mui, Michael Grimbergen
Life of this patent
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Abstract
A method and apparatus for monitoring, measuring and/or controlling the etch rate in a dry etch semiconductor wafer processing system. The wafer processing system has a monitoring assembly which comprises an electromagnetic radiation source and detector which interferometrically measures the etch rate. The actual rate of change of the etch as it progresses is measures by this technique and is compared to a model of a desired rate of change in a controller. The error between the actual rate of change and the desired rate of change is then used to vary at least one of the process parameters of the system in a direction tending to null the difference.
Claims21
Apparatus for controlling a wafer processing system having a chamber and a pedestal within said chamber, the apparatus comprising:
- an interferometer for generating a signal indicative of a rate of an aspect ratio dependent etch (ARDE) occurring within said chamber;
- and
- a controller coupled to said interferometer and said wafer processing system, for varying one or more process parameters of said wafer processing system in response to said signal, wherein the controller comprises a memory and an etch rate processing routine to control the rate of the aspect ratio dependent etch, the etch rate processing routine being capable of executing the steps of:
- retrieving a predetermined etch rate schedule from the memory of the controller, the predetermined etch rate schedule comprising a function of desired aspect ratio dependent etch rate over time;
- mesuring an actual aspect ratio dependent etch rate by measuring the elapsed time between two conjugate maxima or minima points of the signal generated by the interferometer;
- comparing the actual aspect ratio dependent etch rate to the desired aspect ratio dependent etch rate in the retrieved predetermined etch rate schedule;
- and
- varying one or more of the process parameters of the wafer processing system to change the actual aspect ratio dependent etch rate occurring in the chamber to substantially follow the desired aspect ratio dependent etch rate.
5 more elements
An apparatus for controlling a wafer processing system having a chamber comprising a pedestal to support a substrate for the etching of features on the substrate, the apparatus comprising:
- an interferometer capable of generating a signal indicative of an etch rate that is dependent upon an aspect ratio of a feature being etched on the substrate;
- and
- a controller coupled to the interferometer and the wafer processing system, the controller being adapted to vary one or more process pararmeters of the wafer processing system in response to the signal, the process parameters comprising one or more of an RF power supplied to a gas in the chamber, a flow rate of a gas flowing into the chamber, a pressure in the chamber, and a temperature in the chamber, wherein the controller comprises a memory and an etch rate processing routine to control the etch rate, the etch rate processing routine being capable of executing the steps of:
- retrieving a predetermined etch rate schedule from the memory of the controller, the predetermined etch rate schedule comprising a function of desired aspect ratio dependent etch rate over time;
- measuring an actual aspect ratio dependent etch rate by measuring the elapsed time between two conjugate maxima or minima points of the signal generated by the interferometer;
- comparing the actual aspect ratio dependent etch rate to the desired aspect ratio dependent etch rate in the retrieved predetermined etch rate schedule;
- and
- varying one or more of the process parameters to change the actual aspect ratio dependent etch rate to substantially follow the desired aspect ratio dependent etch rate.
5 more elements
An apparatus for etching a substrate, the apparatus comprising:
- a chamber comprising a pedestal capable of supporting a substrate:
- a reactive gas source for delivering a reactive gas to the chamber and an excitation source capable of energizing the reactive gas to etch the substrate;
- an interferometer capable of generating a signal indicative of an actual aspect ratio dependent etch rate of the features being etched on the substrate;
- and
- a controller coupled to the interferometer, the controller being adapted to vary one or more process parameters in response to the signal, wherein the controller comprises a memory and an etch rate processing routine to control the actual aspect ratio dependent etch rate, the etch rate processing routine capable of executing the steps of:
- retrieving a predetermined etch rate schedule from the memory of the controller, the predetermined etch rate schedule comprising a function of desired aspect ratio dependent etch rate over time;
- comparing the actual aspect ratio dependent etch rate to the desired aspect ratio dependent etch rate in the predetermined etch rate schedule that is stored in a memory of the controller;
- and
- varying one or more process parameters of the wafer processing system to change the actual aspect ratio dependent etch rate occurring in the chamber to substantially follow the desired aspect ratio dependent etch rate.
6 more elements
An apparatus for etching a substrate, the apparatus comprising:
- a chamber comprising a pedestal capable of supporting a substrate;
- a reactive gas source for delivering a reactive gas to the chamber and an excitation source capable of energizing the reactive gas to etch the substrate;
- an interferometer to monitor features being etched in the substrate and generate a signal indicative of an actual aspect ratio dependent etch rate of the features being etched on the substrate;
- and
- a controller coupled to the interferometer, the controller comprising a memory and an etch rate processing routine capable of:
- receiving the signal from the interferometer;
- evaluating the signal to determine the actual aspect ratio dependent etch rate;
- during the processing of a first substrate, monitoring the actual aspect ratio dependent etch rate to generate an actual aspect ratio dependent etch rate profile and storing the actual aspect ratio dependent etch rate profile in the memory of the controller;
- retrieving a desired aspect ratio dependent etch rate profile from the memory of the controller;
- comparing the actual aspect ratio dependent etch rate profile to the desired aspect ratio dependent etch rate profile to generate an etch rate error;
- and
- during the processing of a second substrate, varying one or more process parameters of the wafer processing system in relation to the etch rate error.
9 more elements
An apparatus for etching a substrate, the apparatus comprising:
- a chamber comprising a pedestal capable of supporting a substrate;
- a reactive gas source for delivering a reactive gas to the chamber and an excitation source capable of energizing the reactive gas to etch the substrate;
- an interferometer to monitor features being etched in the substrate and generate a signal indicative of an actual etch rate of the features being etched on the substrate;
- and
- a controller coupled to the interferometer, the controller comprising a memory and an etch rate processing routine capable of:
- receiving the signal from the interferometer;
- evaluating the signal to determine a rate of change of the actual etch rate;
- comparing the rate of change of the actual etch rate to a desirable rate of change of an etch rate;
- and
- varying one or more process parameters to change the rate of change of the actual etch rate of the features being etched in the substrate.
7 more elements
Dependencies are inferred from the claim text.