Apparatus and method of detecting endpoint of a dielectric etch

• US 6,517,669 B2
• Filed: 02/26/1999
• Issued: 02/11/2003
• Est. Priority Date: 02/26/1999
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Chapman, James Malden
• Primary Examiner(s): Mills, Gregory
• Assistant Examiner(s): MACARTHUR, SYLVIA
• Application Number:
  US09/261,601
• Publication Number:
  US 20020084253A1
• Time in Patent Office: 1,446 Days
• Field of Search: 156/345, 156/345.25, 250/338.14, 216/83, 216/86
• US Class Current: 156/345.25
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32963 End-point detection

Abstract

A system detects the clearing of a dielectric at a plurality of contact sites by measuring the surface voltage of the dielectric and comparing the surface voltage to a reference voltage set to a value that relates to the cleared contact sites. Another system detects the clearing of a dielectric at a plurality of contact sites on a substrate by measuring the rate of change of a substrate current during an etch process and ending the etch process when the rate of change is approximately zero. Another system detects the clearing of a dielectric at a contact site by measuring a substrate current during an etch process and ends the etch process when the measured substrate current exceeds a predetermined value.

Claims

1. A system for identifying completion of a dielectric etching process on a semiconductor substrate having a dielectric, and the dielectric having a surface voltage, the system comprising:

a voltage probe for measuring the surface voltage of the dielectric to produce a measured voltage; and

an electronic comparator for comparing the measured voltage to a reference voltage.

2. The system of claim 1, wherein the voltage probe is a non-contact probe.

3. The system of claim 1, wherein the electronic comparator is an analog comparator.

4. The system of claim 1, wherein the electronic comparator is a digital comparator.

5. The system of claim 1, wherein the reference voltage is set to a value approximately equal to the surface voltage of the dielectric when the contact is cleared of the dielectric.

6. A system for identifying completion of a dielectric etching process comprising:

a plasma etch chamber;

a semiconductor substrate having a dielectric, the dielectric having a surface voltage, and

the substrate is located in the plasma etch chamber;

a voltage probe for measuring the surface voltage to produce a measured voltage; and

an electronic comparator for comparing the measured voltage to a reference voltage.

7. The system of claim 6 wherein the voltage probe is a non-contact probe.

8. The system of claim 6, wherein the electronic comparator is an analog comparator.

9. The system of claim 6, wherein the electronic comparator is a digital comparator.

10. The system of claim 6, wherein the reference voltage is set to a value approximately equal to the surface voltage of the dielectric when the contact is cleared of the dielectric.

11. A system for identifying completion of an etching process comprising:

a plasma etch chamber;

a substrate in the plasma etch chamber; and

a circuit coupled to the substrate and operable for identifying when a substrate current exceeds a particular value.

12. The system of claim 11, wherein the particular value is the substrate current at a time when a plurality of contacts is cleared.

13. The system of claim 11, wherein the circuit is capable of operating during a plasma etching process.

14. A system for identifying completion of an etching process comprising:

a plasma etch chamber;

a substrate having a material layer having a plurality of contacts, the substrate is located inside the plasma etch chamber; and

a circuit coupled to the substrate and operable for identifying when a substrate current exceeds a particular value.

15. The system of claim 14, wherein the particular value is a value of the substrate current at a time when the plurality of contacts is cleared of the material.

16. A system for identifying completion of an etching process comprising:

a plasma etch chamber;

a substrate having a material layer having a plurality of contacts, the substrate is located inside the plasma etch chamber; and

an ammeter coupled to the substrate and calibrated to indicate a substrate current at which the etching process is complete.

17. The system of claim 16, wherein the ammeter is calibrated to indicate the substrate current at which the plurality of contacts is cleared of the material.

18. A system for identifying completion of an etching process comprising:

a plasma etch chamber;

a substrate having a material layer having a plurality of contacts, the substrate is located inside the plasma etch chamber; and

a computer system coupled to the substrate and operable for identifying when a substrate current exceeds a reference current.

19. The system of claim 18, wherein the reference current is the substrate current at which the plurality of contacts is cleared of the material.

20. A system for identifying completion of a dielectric etching process comprising:

a plasma etch chamber;

a substrate having a dielectric layer having a plurality of contacts, the substrate is located inside the plasma etch chamber; and

a circuit coupled to the substrate and operable for identifying when a substrate current exceeds a particular value.

21. The system of claim 20, wherein the particular value is the substrate current at which the plurality of contacts is cleared of the dielectric.

22. A system for identifying completion of a dielectric etching process comprising:

a plasma etch chamber;

a substrate having a dielectric layer having a plurality of contacts, the substrate is located inside the plasma etch chamber; and

an ammeter coupled to the substrate and calibrated to indicate a substrate current at which the dielectric etching process is complete.

23. The system of claim 22, wherein the ammeter is calibrated to indicate the current at which the plurality of contacts is cleared of the dielectric.

24. A system for identifying completion of a dielectric etching process comprising:

a plasma etch chamber;

a substrate having a dielectric layer having a plurality of contacts, the substrate is located inside the plasma etch chamber; and

a computer system coupled to the substrate and operable for identifying when a substrate current exceeds a particular value.

25. The system of claim 24, wherein the particular value is the substrate current at which the plurality contacts is cleared of the dielectric.