SYSTEMS AND METHODS FOR INTERNAL SURFACE CONDITIONING IN PLASMA PROCESSING EQUIPMENT

• US 20160104648A1
• Filed: 10/14/2014
• Published: 04/14/2016
• Est. Priority Date: 10/14/2014
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Park, Soonam, Zhu, Yufei, Suarez, Edwin C., Ingle, Nitin K., Lubomirsky, Dmitry, Huang, Jiayin
• Granted Patent: US 9,355,922 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C23C 16/455 characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
• CPC Class Codes: C23C 16/45536 Use of plasma, radiation or electromagnetic fields
• CPC Class Codes: C23C 16/45559 Diffusion of reactive gas to substrate
• CPC Class Codes: C23C 16/50 using electric discharges generation and control of plasma in discharge tubes for surface treatment H01J37/32, H01J37/34
• CPC Class Codes: C23C 16/505 using radio frequency discharges
• CPC Class Codes: C23C 16/52 Controlling or regulating the coating process C23C16/45557, C23C16/279 take precedence
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32119 Windows
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32532 Electrodes
• CPC Class Codes: H01J 37/3255 Material
• CPC Class Codes: H01J 37/32623 Mechanical discharge control means
• CPC Class Codes: H01J 37/32972 Spectral analysis
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/32137 of silicon-containing layers
• CPC Class Codes: H01L 21/67069 for drying etching
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 22/26 Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement endpoint detection arrangements in CMP apparatus B24B37/013, in discharge apparatus H01J37/32

Abstract

A method of conditioning internal surfaces of a plasma source includes flowing first source gases into a plasma generation cavity of the plasma source that is enclosed at least in part by the internal surfaces. Upon transmitting power into the plasma generation cavity, the first source gases ignite to form a first plasma, producing first plasma products, portions of which adhere to the internal surfaces. The method further includes flowing the first plasma products out of the plasma generation cavity toward a process chamber where a workpiece is processed by the first plasma products, flowing second source gases into the plasma generation cavity. Upon transmitting power into the plasma generation cavity, the second source gases ignite to form a second plasma, producing second plasma products that at least partially remove the portions of the first plasma products from the internal surfaces.

Claims

1. A method of conditioning one or more internal surfaces of a plasma source, comprising:

flowing one or more first source gases into a plasma generation cavity of the plasma source, the plasma generation cavity being enclosed at least in part by the one or more internal surfaces;

transmitting power into the plasma generation cavity to generate a first plasma, wherein;

the one or more first source gases ignite to form the first plasma, producing first plasma products, and

portions of the first plasma products adhere to the one or more internal surfaces;

flowing the first plasma products out of the plasma generation cavity toward a process chamber where a workpiece is processed by the first plasma products;

flowing one or more second source gases into the plasma generation cavity;

transmitting power into the plasma generation cavity to generate a second plasma, wherein

the one or more second source gases ignite to form the second plasma, producing second plasma products; and

the second plasma products at least partially remove the portions of the first plasma products from the one or more internal surfaces.

2. The method of claim 1, wherein:

the one or more internal surfaces are substantially planar, perforated surfaces that face one another across the plasma generation cavity;

flowing the one or more first source gases into the plasma generation cavity comprises flowing the first source gases through perforations in an upstream one of the internal surfaces;

transmitting power into the plasma generation cavity comprises utilizing the internal surfaces as electrodes across which radio frequency (RF) power is connected; and

flowing the first plasma products out of the plasma generation cavity toward a process chamber comprises flowing the plasma products through perforations in a downstream one of the internal surfaces.

3. The method of claim 2, wherein the plasma generation cavity is bounded by the substantially planar, perforated surfaces and an insulator comprising a ceramic ring that is disposed against a periphery of each of the substantially planar, perforated surfaces, the ceramic ring forming an optical port;

the method further comprising;

capturing optical emissions from at least one of the first plasma and the second plasma through the optical port as an optical signal in a fiber optic;

delivering the optical signal through the fiber optic to an optical emission spectrometer; and

identifying emission peaks with the optical emission spectrometer to monitor the conditioning of the internal surfaces.

4. The method of claim 3, further comprising:

performing sequential repetitions of the steps of flowing the one or more first source gases, transmitting the power into the plasma generation cavity to generate the first plasma, flowing the one or more second source gases, and transmitting the power into the plasma generation cavity to generate the second plasma; and

adjusting a parameter of the second plasma based on the emission peaks, to improve consistency of the first plasma on the next repetition.

5. The method of claim 4, wherein adjusting the parameter of the second plasma comprises adjusting one or more of

a power level transmitted into the plasma generation cavity;

concentration of one or more of the second source gases;

a pressure of the second plasma; and

time during which the power is transmitted into the plasma generation cavity to generate the second plasma.

6. The method of claim 1, wherein:

the one or more internal surfaces comprise yttria;

the workpiece comprises silicon;

the workpiece is processed by the first plasma products etching the silicon;

flowing the one or more first source gases comprises flowing at least NF₃ and H₂ as the first source gases;

the portion of the plasma products that adhere to the one or more internal surfaces include H radicals that adhere to the yttria;

flowing the one or more second source gases comprises flowing at least a fluorine-containing gas as the second source gas; and

the second plasma products include F radicals that remove at least some of the H radicals from the yttria.

7. The method of claim 6, wherein the workpiece is a semiconductor wafer, and further comprising:

loading the wafer into the process chamber before flowing the first source gases; and

unloading the wafer from the process chamber before flowing the second source gases.

8. The method of claim 1, wherein:

the one or more internal surfaces comprise yttria;

the workpiece comprises silicon nitride;

the workpiece is processed by the first plasma products etching the silicon nitride;

flowing the one or more first source gases comprises flowing at least NF₃ as the first source gas;

the portion of the plasma products that adhere to the one or more internal surfaces include F radicals that adhere to the yttria;

flowing the one or more second source gases comprises flowing at least a hydrogen-containing gas as the second source gas; and

the second plasma products include H radicals that remove at least some of the F radicals from the yttria.

9. The method of claim 8, wherein the workpiece is a semiconductor wafer, and further comprising:

loading the wafer into the process chamber before flowing the first source gases; and

unloading the wafer from the process chamber before flowing the second source gases.

10. The method of claim 8, wherein the workpiece is a semiconductor wafer, and further comprising:

loading the wafer into the process chamber before flowing the first source gases; and

flowing the second source gases and transmitting the power into the plasma generation cavity to generate the second plasma before unloading the wafer from the process chamber.

11. A method of conditioning one or more internal surfaces of a plasma source after the internal surfaces are exposed to atmospheric air, comprising:

flowing at least a hydrogen-containing gas into a plasma generation cavity of the plasma source, the plasma generation cavity being enclosed at least in part by the one or more internal surfaces;

transmitting power into the plasma generation cavity to generate a hydrogen-containing plasma, such that H radicals remove excess oxygen from the internal surfaces; and

monitoring emission peaks of the plasma until the emission peaks are stable.

12. The method of claim 11, wherein:

the hydrogen-containing gas comprises at least one of NH₃ and H₂;

flowing at least the hydrogen-containing gas and transmitting the power to generate the plasma are portions of a process sequence, and

monitoring the emission peaks comprises forming at least one emission peak record for each repetition of the process sequence;

and further comprising;

calculating a stability metric of the emission peak records over multiple process sequences.

13. The method of claim 11, further comprising, after transmitting the power into the plasma generation cavity to generate the hydrogen-containing plasma:

flowing at least a fluorine-containing gas into the plasma generation cavity;

transmitting power into the plasma generation cavity to generate a fluorine-containing plasma, and

wherein monitoring the emission peaks comprises monitoring H emission peaks, during the fluorine-containing plasma, until the H emission peaks are stable.

14. The method of claim 13, the fluorine-containing gas comprising NF₃.

15. A method of maintaining stability of a process attribute of a plasma processing system that etches material from wafers, comprising:

generating an etch plasma within the plasma processing system to create etch plasma products, wherein portions of the etch plasma products adhere to one or more internal surfaces of the plasma processing system;

using the etch plasma products to etch the material from the one of the wafers, wherein the portions of the etch plasma products adhered to the one or more internal surfaces affect the process attribute; and

generating a conditioning plasma within the plasma processing system to create conditioning plasma products, wherein the conditioning plasma products remove at least some of the etch plasma products adhered to the one or more internal surfaces.

16. The method of claim 15, further comprising loading one of the wafers into the plasma processing system before generating the etch plasma, and unloading the one of the wafers from the plasma processing system before generating the conditioning plasma.

17. The method of claim 15, further comprising

repeating generating the etch plasma, using the etch plasma products to etch the material, and generating the conditioning plasma;

capturing an optical signal from one of the etch plasma and the conditioning plasma representative of an amount of the etch plasma products adhered to the one or more internal surfaces; and

adjusting a parameter of the conditioning plasma based on the optical signal in one repetition of the conditioning plasma, to correct variations in the amount of the etch plasma products adhered to the internal surfaces for a subsequent repetition of the etch plasma.

18. The method of claim 15, wherein the material is polysilicon, the process stability being maintained is etch rate of the polysilicon, generating the etch plasma comprises generating H radicals, and generating the conditioning plasma comprises generating F radicals.

19. The method of claim 15, wherein the material is silicon nitride, the process stability being maintained is selectivity of the etch to silicon nitride over silicon dioxide, generating the etch plasma comprises generating F radicals, and generating the conditioning plasma comprises generating H radicals.