WAFER DRYING SYSTEM

• US 20200135501A1
• Filed: 05/24/2019
• Published: 04/30/2020
• Est. Priority Date: 10/30/2018
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: HSU, Wei-Chun, Wu, Sheng-Wei, Wang, Shu-Yen
• Granted Patent: US 11,581,199 B2
• Time in Patent Office: Days
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: H01L 21/67034 for drying
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring

Abstract

The present disclosure is directed to a wafer drying method that detects molecular contaminants in a drying gas as a feedback parameter for a multiple wafer drying process. For example, the method includes dispensing, in a wafer drying module, a drying gas over a batch of wafers. Further, the method includes collecting the drying gas from an exhaust of the wafer drying module and determining the concentration of contaminants in the drying gas. The method also includes re-dispensing the drying gas over the batch of wafers if the concentration of contaminants is greater than a baseline value and transferring the batch of wafers out of the wafer drying module if the concentration is equal to or less than the baseline value.

Claims

1. A wafer drying system, comprising:

a wafer drying module configured to spin a batch of wafers and to dispense a drying gas over the batch of wafers;

an analyzer configured to detect molecular contaminants dispersed in the drying gas from the wafer drying module and to determine a concentration of the molecular contaminants; and

circuitry configured to;

compare the concentration of the molecular contaminants to a baseline value; and

in response to the concentration being greater than the baseline value, command the wafer drying module to re-spin and flow additional drying gas over the batch of wafers.

2. The wafer drying system of claim 1, wherein the circuitry is further configured to, in response to the concentration of the molecular contaminants in the drying gas being equal to or less than the baseline value, remove the batch of wafers from the wafer drying module.

3. The wafer drying system of claim 1, wherein the analyzer is configured to detect molecular contaminants dispersed in the drying gas.

4. The wafer drying system of claim 1, wherein the molecular contaminants comprise volatile organic compounds, amines, inorganic acids, acetone, sulfur dioxide, isopropyl alcohol, water, or combinations thereof.

5. The wafer drying system of claim 1, wherein the drying gas comprises an inert gas or dry air.

6. The wafer drying system of claim 5, wherein the inert gas comprises nitrogen, argon, or helium.

7. The wafer drying system of claim 1, wherein the analyzer comprises a time of flight mass spectrometer, an ion mobility spectrometer, a humidity detector, or combinations thereof.

8. The wafer drying system of claim 1, further comprising:

a cluster tool that houses the wafer drying module and the circuitry; and

a detector unit configured to collect the drying gas from the wafer drying module and to transfer the collected drying gas to the analyzer.

9. A method of drying a batch of wafers, comprising:

spinning the batch of wafers in a wafer drying module;

dispensing, in the wafer drying module, a drying gas over the batch of wafers;

collecting the drying gas from an exhaust line of the wafer drying module;

analyzing the collected drying gas to determine a concentration of contaminants dissolved in the drying gas;

in response to the concentration of contaminants being greater than a baseline value, re-spinning the batch of wafers while re-dispensing the drying gas over the batch wafers; and

in response to the concentration being equal to or less than the baseline value, transferring the batch of wafers outside the wafer drying module.

10. The method of claim 9, wherein the contaminants comprise airborne molecular contaminants.

11. The method of claim 10, wherein the drying gas does not chemically react with the airborne molecular contaminants.

12. The method of claim 10, wherein the airborne molecular contaminants comprise volatile organic compounds, amines, inorganic acids, acetone, sulfur dioxide, isopropyl alcohol, water, or combinations thereof.

13. The method of claim 9, wherein the drying gas comprises nitrogen, argon, helium, or dry air.

14. The method of claim 9, further comprising:

after re-spinning the batch of wafers while re-dispensing the drying gas over the batch of wafers, collecting the re-dispensed drying gas from the wafer drying module;

analyzing the collected re-dispensed drying gas to determine another concentration of contaminants in the collected re-dispensed drying gas;

in response to the other concentration of contaminants being greater than the baseline value, performing another spinning of the batch of wafers while dispensing the drying gas over the batch of wafers; and

in response to the other concentration of contaminants being equal to or less than the baseline value, transferring the batch of wafers outside the wafer drying module.

15. A multiple wafer drying system, comprising:

a wafer drying module configured to dry a plurality of wafers by spinning the plurality of wafers and dispensing a drying gas over the plurality of wafers;

a detector configured to collect, from an exhaust line of the wafer drying module, the drying gas dispensed over the plurality of wafers;

an analyzer configured to analyze the collected drying gas and to output a concentration of one or more airborne molecular contaminants in the drying gas; and

circuitry configured to;

compare the concentration of the one or more airborne molecular contaminants to respective one or more values;

in response to the concentration of the one or more airborne molecular contaminants being equal to or less than the respective one or more values, command the wafer drying module to remove the plurality of wafers from the drying module; and

in response to the concentration of the one or more airborne molecular contaminants being greater than the respective one or more values, command the wafer drying module to re-spin the plurality of wafers and re-dispense the drying gas over the plurality of wafers.

16. The multiple wafer drying system of claim 15, wherein the drying gas is a carrier gas for the one or more airborne molecular contaminants.

17. The multiple wafer drying system of claim 15, wherein the circuitry is further configured to, in response to the concentration of the one or more airborne molecular contaminants being greater than the respective one or more values, command the wafer drying module to continue drying the plurality of wafers.

18. The multiple wafer drying system of claim 15, wherein the analyzer comprises a time of flight mass spectrometer, an ion mobility spectrometer, a humidity detector, or combinations thereof.

19. The multiple wafer drying system of claim 15, wherein the one or more airborne molecular contaminants comprise volatile organic compounds, amines, inorganic acids, acetone, sulfur dioxide, isopropyl alcohol, water vapors, or combinations thereof.

20. The multiple wafer drying system of claim 15, wherein the drying gas comprises nitrogen, helium, argon, or dry air.