Etching end-point detecting method

• US 6,586,262 B1
• Filed: 11/16/2001
• Issued: 07/01/2003
• Est. Priority Date: 05/18/1999
• Status: Expired due to Term

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Sakano, Shinji, Saito, Susumu
• Primary Examiner(s): Powell, William A.
• Application Number:
  US09/926,544
• Time in Patent Office: 592 Days
• Field of Search: 438/9, 438/14, 438/16, 438/710, 438/735, 216/60, 216/67, 156/345.25
• US Class Current: 438/9
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32972 Spectral analysis

Abstract

The present invention is a method for end point detection where emission spectra are detected during etching of an object to be processed, such as a semiconductor wafer, by a spectrometer, and an end point of the etching is detected, comprising performing etching of a sample, corresponding to a product, prior to etching of a semiconductor wafer which is the product, sequentially measuring full-spectra of plasma, performing principal component analysis of the emission spectra using the emission intensities of all wavelengths of each of the full-spectra, holding the results as data, thereafter obtaining a principal component score for each of the full-spectra sequentially measured during etching of a semiconductor wafer to be manufactured on the basis of the emission intensities of all the wavelengths, and then detecting an end point of etching on the basis of a substantial change of the principal component score for each of the full-spectra sequentially measured.

Claims

1. A method for end point detection of etching where, when an object to be processed is etched using plasma, emission spectra of plasma are sequentially measured by light detecting means, an end point of etching is detected on the basis of change of the emission spectra, comprising:

the step of etching a sample (the same kind as the following object to be processed) of the object prior to etching the object to sequentially measure full-spectra of plasma during the etching; and

the step of obtaining weighting factors for each wavelength, the weighting factors weighting all wavelengths of each full-spectrum accumulated until an etching end of the sample according to respective emission intensities, and further comprising;

the step of adding the emission intensities of all the wavelengths for each of the full-spectra sequentially measured during etching of the object in addition with the respective weighting factors; and

the step for an end point detection of etching of detecting an end point of etching on the basis of the degree of change of an additional value of the emission intensities for each of full-spectra sequentially measured.

2. A method for end point detection of etching according to claim 1, wherein the degree of the change of the additional value in the step for an end point detection of etching is judged on the basis of a differential value of the additional value and a time point at which the differential value changes most largely is detected as an end point of etching.

3. A method for end point detection of etching according to claim 2, wherein, in the degree of the change of the additional value in the step for an end point detection of etching, when large changes of the differential value of the additional value are observed at two points, the time of the change in the latter half is detected as the end point of etching.

4. A method for end point detection of etching where, when an object to be processed is etched using plasma, emission spectra of plasma are sequentially measured by light detecting means, an end point of etching is detected on the basis of change of the emission spectra, comprising:

the step of etching a sample (the same kind as the following object to be processed) of the object prior to etching the object to sequentially measure full-spectra of plasma during the etching; and

the step of using emission intensities of all wavelengths of each of full-spectra sequentially measured during etching of the object to perform a main component analysis, and further comprising;

the step of obtaining principal component scores for each of the full-spectra accumulated until the end of etching of the sample on the basis of the emission intensities of all the wavelengths and a principal component expression obtained in the principal component analysis; and

the step of detecting the end point of etching on the basis of the degree of change of a principal component score for each of the full-spectra sequentially measured.

5. A method for end point detection of etching according to claim 4, wherein the principal component score is a first principal component score obtained from a characteristic value and a characteristic vector.

6. A method for end point detection of etching according to claim 5, wherein the degree of the change of the additional value in the step for an end point detection of etching is judged on the basis of a differential value of the additional value and a time point at which the slope of the differential value has changed is detected as the end point of etching.