ATR-FTIR metal surface cleanliness monitoring

• US 20030179368A1
• Filed: 03/19/2002
• Published: 09/25/2003
• Est. Priority Date: 03/19/2002
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Jang, Syun-Ming, Li, Lain-Jong, Ko, Chung-Chi
• Granted Patent: US 6,908,773 B2
• Time in Patent Office: Days
• US Class Current: 356/237.2
• CPC Class Codes: G01N 2021/3595 using FTIR
• CPC Class Codes: G01N 21/35 using infrared light G01N21/39 takes precedence
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/552 Attenuated total reflection
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence

Abstract

Attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) metal surface cleanliness monitoring is disclosed. A metal surface of a semiconductor die is impinged with an infrared (IR) beam, such as can be accomplished by using an ATR technique. The IR beam as reflected by the metal surface is measured. For instance, an interferogram of the reflected IR beam may be measured. A Fourier transform of the interferogram may also be performed, in accordance with an FTIR technique. To determine whether the metal surface is contaminated, the IR beam as reflected is compared to a reference sample. For example, the Fourier transform of the interferogram may be compared to the reference sample. If there is deviation by more than a threshold, the metal surface may be concluded as being contaminated.

Claims

1. A method comprising:

impinging a metal surface of a semiconductor die with an infrared (IR) beam;

measuring the IR beam as reflected by the metal surface; and

,

determining whether the metal surface is contaminated based on the IR beam as reflected by the metal surface.

2. The method of claim 1, wherein impinging the metal surface of the semiconductor die with the IR beam comprises employing an attenuated total reflectance (ATR) technique.

3. The method of claim 1, wherein measuring the IR beam as reflected by the metal surface comprises measuring an interferogram of the metal surface, and performing a Fourier transform on the interferogram.

4. The method of claim 3, wherein determining whether the metal surface is contaminated based on the IR beam as reflected by the metal surface comprises comparing the Fourier transform of the interferogram to a reference sample, and concluding that the metal surface is contaminated when the Fourier transform of the interferogram deviates from the reference sample by more than a threshold.

5. The method of claim 1, wherein determining whether the metal surface is contaminated based on the IR beam as reflected by the metal surface comprises comparing the IR beam as reflected by the metal surface to a reference sample, and concluding that the metal surface is contaminated when the IR beam as reflected thereby deviates from the reference sample by more than a threshold.

6. The method of claim 1, further comprising repeating impinging the metal surface of the semiconductor die, measuring the IR beam as reflected, and determining whether the metal surface is contaminated as an in-line process for each of a number of additional semiconductor dies.

7. The method of claim 1, wherein the metal surface comprises a bonding pad.

8. A method comprising:

transferring a semiconductor wafer to a stage;

for each of a number of semiconductor dies of the semiconductor wafer,

positioning a metal surface of the semiconductor die under an infrared (IR) probe;

impinging the metal surface of the semiconductor die with an IR beam by the IR probe;

measuring the IR beam as reflected by the metal surface;

determining whether the metal surface of the semiconductor die is contaminated based on the IR beam as reflected by the metal surface; and

,

transferring the semiconductor wafer from the stage.

9. The method of claim 8, wherein impinging the metal surface of the semiconductor die with the IR beam comprises employing an attenuated total reflectance (ATR) technique.

10. The method of claim 8, wherein measuring the IR beam as reflected by the metal surface comprises measuring an interferogram of the metal surface, and performing a Fourier transform on the interferogram.

11. The method of claim 10, wherein determining whether the metal surface is contaminated based on the IR beam as reflected by the metal surface comprises comparing the Fourier transform of the interferogram to a reference sample, and concluding that the metal surface is contaminated when the Fourier transform of the interferogram deviates from the reference sample by more than a threshold.

12. The method of claim 8, wherein determining whether the metal surface is contaminated based on the IR beam as reflected by the metal surface comprises comparing the IR beam as reflected by the metal surface to a reference sample, and concluding that the metal surface is contaminated when the IR beam as reflected thereby deviates from the reference sample by more than a threshold.

13. The method of claim 8, further comprising repeating the method for each of a number of additional semiconductor wafers.

14. The method of claim 8, wherein the metal surface comprises a bonding pad.

15. A system comprising:

a stage on which a semiconductor wafer having a number of semiconductor dies is positionable, each semiconductor die having a metal surface;

an infrared (IR) probe positionable over each metal surface of each semiconductor die of the semiconductor wafer, and capable of measuring an IR beam incident to the metal surface as reflected by the metal surface;

a pattern recognition component capable of comparing the IR beam as reflected by the metal surface to a reference sample to determine whether the metal surface is clean.

16. The system of claim 15, further comprising a wafer handling system to transfer the semiconductor to and from the stage.

17. The system of claim 15, wherein the IR probe is an attenuated total reflectance (ATR)-IR probe.

18. The system of claim 15, wherein the pattern recognition component performs a Fourier transform IR (FTIR) analysis of the IR beam as reflected by the metal surface by performing a Fourier Transform of the IR beam as represented by an interferogram, and comparing the Fourier Transform performed to the reference sample.

19. The system of claim 15, wherein the pattern recognition component comprises a software component.

20. The system of claim 15, wherein the metal surface comprises a bonding pad.