Dilute remote plasma clean

• US 6,329,297 B1
• Filed: 04/21/2000
• Issued: 12/11/2001
• Est. Priority Date: 04/21/2000
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Balish, Kenneth E., Beals, Mark, Tanaka, Tsutomu, Nowak, Thomas
• Primary Examiner(s): Powell, William A.
• Application Number:
  US09/553,694
• Time in Patent Office: 599 Days
• Field of Search: 438/712, 438/714, 438/723, 438/726, 438/727, 438/729, 438/730, 438/743, 134/1.1, 134/31, 156/345.P, 156/345.MW, 216/67, 216/69, 216/79
• US Class Current: 438/714
• CPC Class Codes: H01J 2237/335 Cleaning
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: Y10S 156/916 Differential etching apparatus including chamber cleaning means or shield for preventing deposits

Abstract

A method and apparatus for enhancing the etch characteristics of a plasma formed in a remote plasma generator. A plasma formed in a remote plasma generator (27) is flown through a tube (62) to a plenum (60) where it is diluted to form a plasma mixture before flowing the plasma mixture into a processing chamber (15). The plasma mixture is used to clean deposits from the interior surfaces of the processing chamber, or can be used to perform an etch step on a process wafer within the processing chamber. In one embodiment, a plasma formed from NF₃ is diluted with N₂ to etch residue from the surfaces of a processing chamber used to deposit silicon oxide glass. Diluting the plasma increased the etching rate and made the etching rate more uniform across the diameter of the processing chamber.

Claims

1. A method of cleaning deposits of dielectric material from a deposition chamber, the method comprising:

flowing a cleaning plasma precursor into a remote plasma generator;

irradiating the cleaning plasma precursor in the remote plasma generator to form a cleaning plasma suitable for cleaning the deposits of dielectric material from surfaces of the deposition chamber;

flowing the cleaning plasma from the remote plasma generator to a plenum;

mixing the cleaning plasma with a non-reactive diluent gas in a selected ratio of diluent gas flow to cleaning plasma precursor flow to form an etching mixture with an enhanced etching characteristic, the selected ratio being between about 1;

1 to less than 2;

1; and

flowing the cleaning mixture into the deposition chamber to remove the dielectric material from surfaces of the deposition chamber.

2. The method of claim 1 wherein the dielectric material comprises silicon oxide glass, the non-reactive diluent gas comprises nitrogen, and the cleaning plasma precursor comprises a fluorine-containing compound.

3. The method of claim 1 wherein the flow of the cleaning mixture maintains a pressure in the deposition chamber of at least about 1 Torr.

4. The method of claim 1 wherein the cleaning plasma precursor flow is greater than about 80 sccm/liter of chamber volume.

5. A method of controlling the etching profile of an substrate processing system, the method comprising:

flowing plasma precursor into a remote plasma generator at a first selected flow rate;

forming an etching plasma from the plasma precursor in the remote plasma generator;

flowing the etching plasma into a plenum;

flowing a diluent gas into the plenum at a second selected flow rate to dilute the etching plasma and form an etching mixture.

6. The method of claim 5 wherein the first selected rate is selected according to a conversion efficiency of the remote plasma generator.

7. A method for etching a process wafer, the method comprising:

placing the process wafer in a processing chamber;

flowing an etching plasma precursor into a remote plasma generator;

irradiating the etching plasma precursor in the remote plasma generator to form an etching plasma;

flowing the etching plasma from the remote plasma generator to a gas mixing region;

mixing the etching plasma with a diluent gas in a selected ratio of plasma precursor flow to diluent gas flow to form an etching mixture; and

flowing the etching mixture into the processing chamber to etch the process wafer.

8. The method of claim 7 wherein the gas mixing region is a plenum formed between a gas box and a blocker plate of a chamber lid.

9. The method of claim 7 wherein the diluent gas flow is coaxial to an etching plasma flow at an inlet to the gas mixing region.

10. The method of claim 7 wherein etching plasma precursor comprises NF₃.

11. The method of claim 7 wherein the diluent gas comprises N₂.

12. The method of claim 7 wherein the process wafer has a dielectric layer on a surface of the process wafer, the etching mixture etching the dielectric layer.

13. The method of claim 12 wherein the dielectric layer comprises silicon oxide glass.

14. The method of claim 7 wherein the selected ratio of plasma precursor flow to diluent flow is about 1:

1.

15. A method for etching a process wafer, the method comprising:

placing the process wafer in a processing chamber, the process wafer having a film of silicon oxide glass;

flowing NF₃ at a first flow rate into a remote microwave plasma generator;

irradiating the NF₃ in the remote microwave plasma generator to form an etching plasma;

flowing the etching plasma from the remote microwave plasma generator to a plenum formed between a gas box and a blocker plate;

flowing N₂ gas into the plenum at a second flow rate, the second flow rate being essentially equal to the first flow rate, an N₂ flow being essentially coaxial with an etching plasma flow at an inlet of the plenum;

mixing the etching plasma with the N₂ gas in the plenum to form an etching mixture; and

flowing the etching mixture into the processing chamber to etch the film of silicon oxide glass.

16. A substrate processing apparatus lid comprising:

a gas dispersion plate,

a lid body, a plenum being formed between the gas dispersion plate and the lid body;

a plasma generator with a plasma outlet;

a separator tube with a plasma inlet coupled to the plasma outlet and a tube outlet coupled to the plenum; and

a diluent conduit, a portion of the diluent conduit being coaxial with the separator tube and having a diluent outlet coupled to the plenum, the diluent outlet being annular to the tube outlet.

17. The lid of claim 16 wherein the separator tube comprises ceramic.

18. A substrate-processing apparatus for cleaning deposits of dielectric material from surfaces of a deposition chamber, the apparatus comprising:

(a) a processing chamber;

(b) a gas delivery system configured to deliver a cleaning plasma precursor to a remote plasma generator and to deliver a diluent gas to a gas mixing block (9), an outlet of the remote plasma generator being coupled to an input of the gas mixing block and an outlet of the gas mixing block being coupled to the processing chamber;

(c) an exhaust system coupled to the processing chamber and capable of maintaining a chamber pressure of at least about 1 Torr at a flow rate into the processing chamber of up to about 1,400 sccm;

(d) a controller configured to control said gas delivery system and said remote plasma generator, and said exhaust system; and

(e) a memory, coupled to said controller, comprising a computer-readable medium having a computer-readable program embodied therein for directing operation of the substrate processing apparatus, said computer-readable program comprising;

(i) a first set of computer instructions for controlling said gas delivery system to flow the cleaning plasma precursor gas into said remote plasma generator at a first flow rate,

(ii) a second set of computer instructions for controlling said gas delivery system to flow the diluent gas into the gas mixing block at a second flow rate, the ratio of the second flow rate to the first flow rate being less than 2;

1, to form a cleaning mixture, and

(iii) a third set of computer instructions for controlling the exhaust system to maintain a pressure within the processing chamber of at least about 1 Torr, the pressure in the processing chamber flowing the cleaning mixture from the gas mixing block into the processing chamber.

19. The apparatus of claim 18 wherein the third set of computer instructions controls the exhaust system to maintain the pressure within the processing chamber between about 1-1.5 Torr.