High Throughput Thin Film Characterization And Defect Detection

• US 20130083320A1
• Filed: 09/25/2012
• Published: 04/04/2013
• Est. Priority Date: 09/27/2011
• Status: Active Grant

• Current Assignee: KLA-Tencor Corporation (KLA Corporation)
• Original Assignee: KLA-Tencor Corporation (KLA Corporation)
• Inventors: Gao, Xiang, Flanner, Philip D. III, Poslavsky, Leonid, Jiang, Zhiming, Kaack, Torsten, Zhao, Qiang, Ye, Jun-Jie (Julien)
• Granted Patent: US 8,711,349 B2
• Time in Patent Office: Days
• US Class Current: 356/237.5
• CPC Class Codes: G01N 21/211 Ellipsometry optical thickness measurement G01B11/06
• CPC Class Codes: G01N 21/8422 Investigating thin films, e.g. matrix isolation method
• CPC Class Codes: G01N 21/8851 Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges G01N21/8806 and G01N21/93 - G01N21/95692 take precedence; optical measurement of dimensions G01B11/00; optical scanning G02B26/10; image transformation G06T3/00; computerised image enhancement G06T5/00; image processing per se for flaw detection G06T7/0002
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14

Abstract

Methods and systems for determining band structure characteristics of high-k dielectric films deposited over a substrate based on spectral response data are presented. High throughput spectrometers are utilized to quickly measure semiconductor wafers early in the manufacturing process. Optical dispersion metrics are determined based on the spectral data. Band structure characteristics such as band gap, band edge, and defects are determined based on optical dispersion metric values. In some embodiments a band structure characteristic is determined by curve fitting and interpolation of dispersion metric values. In some other embodiments, band structure characteristics are determined by regression of a selected dispersion model. In some examples, band structure characteristics indicative of band broadening of high-k dielectric films are also determined. The electrical performance of finished wafers is estimated based on the band structure characteristics identified early in the manufacturing process.

Claims

1. A method comprising:

receiving a spectral response of an unfinished, multi-layer semiconductor wafer across a first spectral range;

determining an optical dispersion metric of a first layer of the multi-layer semiconductor wafer based at least in part on the spectral response;

determining a band structure characteristic indicative of an electrical performance of the first layer of the multi-layer semiconductor wafer based at least in part on the dispersion metric of the multi-layer semiconductor wafer across a second spectral range within the first spectral range; and

determining an estimate of the electrical performance of the multi-layer semiconductor wafer based at least in part on the band structure characteristic.

2. The method of claim 1, wherein the first layer is an electrically insulative layer disposed above a semiconductor substrate.

3. The method of claim 2, wherein the first layer includes an intermediate layer between the semiconductor substrate and the electrically insulative layer.

4. The method of claim 1, wherein the band structure characteristic is an interpolated band gap of the first layer and the determining of the interpolated band gap involves curve fitting and interpolation of the optical dispersion metric.

5. The method of claim 1, wherein the band structure characteristic is a band edge of the first layer and the determining of the band edge involves determining that the optical dispersion metric exceeds a threshold value.

6. The method of claim 1, wherein the band structure characteristic is a band broadening associated with the first layer and the determining of the band broadening involves determining an interpolated band gap and a band edge of the first layer and determining a difference between the band edge and the interpolated band gap.

7. The method of claim 1, wherein the band structure characteristic is a defect and the determining of the defect involves determining whether the optical dispersion metric exceeds a threshold value over a spectral range below a band gap of the first layer.

8. The method of claim 1, further comprising:

determining the spectral response of the unfinished, multi-layer semiconductor wafer based on a measurement of the multi-layer semiconductor wafer with either an ellipsometer or a reflectometer.

9. The method of claim 1, further comprising:

determining an optical dispersion property of a second layer of the multi-layer semiconductor wafer based at least in part on the spectral response; and

determining a band structure characteristic indicative of an electrical performance of the second layer of the multi-layer semiconductor wafer based at least in part on the dispersion property of the second layer.

10. A non-transitory, computer-readable medium, comprising:

code for causing a computer to receive a spectral response of an unfinished, multi-layer semiconductor wafer across a first spectral range;

code for causing the computer to determine an optical dispersion metric of a first layer of the multi-layer semiconductor wafer based at least in part on the spectral response;

code for causing the computer to determine a band structure characteristic indicative of an electrical performance of the first layer of the multi-layer semiconductor wafer based at least in part on the dispersion metric of the multi-layer semiconductor wafer across a second spectral range within the first spectral range; and

code for causing the computer to determine an estimate of the electrical performance of the multi-layer semiconductor wafer based at least in part on the band structure characteristic.

11. The non-transitory, computer-readable medium of claim 10, wherein the band structure characteristic is an interpolated band gap of the first layer and the determining of the interpolated band gap involves curve fitting and interpolation of the optical dispersion metric.

12. The non-transitory, computer-readable medium of claim 10, wherein the band structure characteristic is a band edge of the first layer and the determining of the band edge involves determining that the optical dispersion metric exceeds a threshold value.

13. The non-transitory, computer-readable medium of claim 10, wherein the band structure characteristic is a band broadening associated with the first layer and the determining of the band broadening involves determining an interpolated band gap and a band edge of the first layer and determining a difference between the band edge and the interpolated band gap.

14. The non-transitory, computer-readable medium of claim 10, wherein the band structure characteristic is a defect and the determining of the defect involves determining whether the optical dispersion metric exceeds a threshold value over a spectral range below a band gap of the first layer.

15. The non-transitory, computer-readable medium of claim 10, further comprising:

code for causing the computer to determine an optical dispersion property of a second layer of the multi-layer semiconductor wafer based at least in part on the spectral response; and

code for causing the computer to determine a band structure characteristic indicative of an electrical performance of the second layer of the multi-layer semiconductor wafer based at least in part on the dispersion property of the second layer.

16. A system comprising:

an illuminator;

a spectrometer; and

one or more computer systems configured to;

receive a spectral response of an unfinished, multi-layer semiconductor wafer across a first spectral range;

determine an optical dispersion metric of a first layer of the multi-layer semiconductor wafer based at least in part on the spectral response;

determine a band structure characteristic indicative of an electrical performance of the first layer of the multi-layer semiconductor wafer based at least in part on the dispersion metric of the multi-layer semiconductor wafer across a second spectral range within the first spectral range; and

determine an estimate of the electrical performance of the multi-layer semiconductor wafer based at least in part on the band structure characteristic.

17. The system of claim 16, wherein the band structure characteristic is an interpolated band gap of the first layer and the interpolated band gap is determined at least in part by curve fitting and interpolation of the optical dispersion metric.

18. The system of claim 16, wherein the band structure characteristic is a band edge of the first layer and the the band edge is determined at least in part by determining that the optical dispersion metric exceeds a threshold value.

19. The system of claim 16, wherein the band structure characteristic is a band broadening associated with the first layer and the band broadening is determined at least in part by determining an interpolated band gap and a band edge of the first layer and determining a difference between the band edge and the interpolated band gap.

20. The system of claim 16, wherein the band structure characteristic is a defect and the defect is determined at least in part by determining whether the optical dispersion metric exceeds a threshold value over a spectral range below a band gap of the first layer.

21. The system of claim 16, wherein the one or more computer systems is further configured to:

determine an optical dispersion property of a second layer of the multi-layer semiconductor wafer based at least in part on the spectral response; and

determine a band structure characteristic indicative of an electrical performance of the second layer of the multi-layer semiconductor wafer based at least in part on the dispersion property of the second layer.