Gas distribution system having fast gas switching capabilities

• US 20050241763A1
• Filed: 04/30/2004
• Published: 11/03/2005
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Sadjadi, Reza, Lenz, Eric H., Dhindsa, Rajinder, Huang, Zhisong, Sam, Jose Tong
• Granted Patent: US 7,708,859 B2
• Time in Patent Office: Days
• US Class Current: 156/345.330
• CPC Class Codes: C23C 16/45561 Gas plumbing upstream of the reaction chamber
• CPC Class Codes: C23C 16/45565 Shower nozzles
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow

Abstract

A gas distribution system for supplying different gas compositions to a chamber, such as a plasma processing chamber of a plasma processing apparatus is provided. The gas distribution system can include a gas supply section, a flow control section and a switching section. The gas supply section provides first and second gases, typically gas mixtures, to the flow control section, which controls the flows of the first and second gases to the chamber. The chamber can include multiple zones, and the flow control section can supply the first and second gases to the multiple zones at desired flow ratios of the gases. The gas distribution system can continuously supply the first and second gases to the switching section and the switching section is operable to switch the flows of the first and second gases, such that one of the first and second process gases is supplied to the chamber while the other of the first and second gases is supplied to a by-pass line, and then to switch the gas flows. The switching section preferably includes fast switching valves operable to quickly open and close to allow fast switching of the first and second gases, preferably without the occurrence of undesirable pressure surges or flow instabilities in the flow of either gas.

Claims

1. A gas distribution system for supplying gas to a vacuum chamber, comprising:

a first gas passage and a second gas passage adapted to be in fluid communication with a first gas line;

a third gas passage and a fourth gas passage adapted to be in fluid communication with a second gas line, the first and third gas passages being adapted to supply gas to the vacuum chamber, and the second and fourth gas passages being adapted to supply gas to a by-pass line;

a first fast switching valve arranged along the first gas passage;

a second fast switching valve arranged along the second gas passage;

a third fast switching valve arranged along the third gas passage;

a fourth fast switching valve arranged along the fourth gas passage;

the first and fourth fast switching valves being adapted to receive signals to open while the second and third fast switching valves are closed so that the first gas is supplied to the vacuum chamber via the first gas line and the first and third gas passages while the second gas is supplied to the by-pass line via the second gas line and the second and fourth gas passages; and

the second and third fast switching valves being adapted to receive signals to open while the first and fourth fast switching valves are closed so that the second gas is supplied to the vacuum chamber via the second gas line and the third gas passage while the first gas is supplied to the by-pass line via the first gas line and the second gas passage.

2. The gas distribution system of claim 1, further comprising:

a first flow restrictor adapted to be arranged along the first gas line upstream of the first and second fast switching valves; and

a second flow restrictor adapted to be arranged along the second gas line upstream of the third and fourth fast switching valves;

wherein the first and second flow restrictors are adapted to maintain an approximately constant gas pressure in a region of the first and second gas lines upstream of and proximate the first and second flow restrictors.

3. The gas distribution system of claim 2, wherein the first gas line has a volume between the first flow restrictor and the first and second fast switching valves of less than about 10 cm³, and the second gas line has a volume between the second flow restrictor and the third and fourth fast switching valves of less than about 10 cm³.

4. The gas distribution system of claim 1, further comprising:

a third flow restrictor adapted to be arranged along the first gas passage downstream of the first fast switching valve;

a fourth flow restrictor adapted to be arranged along the second gas passage downstream of the second fast switching valve;

a fifth flow restrictor adapted to be arranged along the third gas passage downstream of the third fast switching valve; and

a sixth flow restrictor adapted to be arranged along the fourth gas passage downstream of the fourth fast switching valve;

wherein the third, fourth, fifth and sixth flow restrictors are adapted to maintain an approximately constant gas pressure in a region of the first, second, third and fourth gas passages upstream of and proximate the respective first, second, third, fourth, fifth and sixth flow restrictors.

5. The gas distribution system of claim 1, further comprising a controller which is operable to control the opening and closing of the first, second, third and fourth fast switching valves.

6. The gas distribution system of claim 1, wherein the first, second, third and fourth fast switching valves can be opened and/or closed within a period of less than about 100 ms, or less than about 50 ms, after receiving a signal.

7. A plasma processing apparatus, comprising:

a plasma processing chamber including a showerhead electrode assembly and having a plasma confinement zone with a volume of about ½

liter to about 4 liters; and

the gas distribution system according to claim 1 in fluid communication with the plasma processing chamber;

wherein the gas distribution system can substantially replace the first gas or the second gas in the plasma zone with the other of the first gas or the second gas within a period of less than about 1 s, or less than about 200 ms.

8. A gas distribution system for supplying gas to a plasma processing chamber including a gas distribution member having inner and outer zones which are flow insulated from each other, the gas distribution system comprising:

a first gas passage adapted to be in fluid communication with a first process gas source, the inner zone of the gas distribution member of the plasma processing chamber and a bypass line;

a second gas passage adapted to be in fluid communication with the first process gas process source, the outer zone of the gas distribution member of the plasma processing chamber and the bypass line;

a third gas passage adapted to be in fluid communication with a second process gas source, the inner zone and the by-pass line;

a fourth gas passage adapted to be in fluid communication with the second process gas source, the outer zone and the by-pass line; and

a plurality of fast switching valves adapted to receive signals to open or close so that (i) the first process gas is supplied to the inner and outer zones via the first and second gas passages, while the second process gas is supplied to the by-pass line via the third and fourth gas passages, and (ii) to change the flows of the first and second process gases so that the second process gas is supplied to the inner and outer zones via the third and fourth gas passages, while the first process gas is supplied to the by-pass line via the first and second gas passages.

9. The gas distribution system of claim 8, further comprising at least one flow restrictor arranged along each of the first, second, third and fourth process gas passages, the flow restrictors being adapted to maintain an approximately constant gas pressure in a region of the first, second, third and fourth gas passages upstream of and proximate the flow restrictors.

10. The gas distribution system of claim 8, wherein the fast switching valves can be opened and/or closed within a period of less than about 100 ms, or less than 50 ms, after receiving a signal.

11. A plasma processing apparatus, comprising:

a plasma processing chamber including a showerhead electrode assembly having the inner and outer zones and an interior volume of about ½

liter to 4 liters; and

the gas distribution system according to claim 8 in fluid communication with the inner and outer zones of the showerhead electrode assembly;

wherein the gas distribution system being operable to substantially replace the first process gas or the second process gas in the plasma confinement zone with the other of the first process gas or the second process gas within a period of less than about 1 s, or less than about 200 ms.

12. A gas distribution system for supplying process gas to a plasma processing chamber including a gas distribution member having inner and outer zones which are flow insulated from each other, the gas distribution system comprising a gas switching section, including:

a plurality of first gas passages each (i) adapted to be in fluid communication with at least one first gas passage and/or at least one second gas passage, and (ii) adapted to be in fluid communication with at least one of the inner zone of the gas distribution member of the plasma processing chamber, the outer zone of the gas distribution member of the plasma processing chamber, and a by-pass line; and

a fast switching valve arrangement adapted to receive signals to (iii) open a first group of fast switching valves and close a second group of fast switching valves to supply a first process gas to the inner and outer zones while a second process gas is diverted to the bypass line, via a first group of the first gas passages, and (iv) to close the first group of fast switching valves and open the second group of fast switching valves to change the first and second process gas flows so as to supply the second process gas to the inner and outer zones while the first process gas is diverted to the bypass line, via a second group of the first gas passages.

13. The gas distribution system of claim 12, further comprising a controller operable to control the opening and closing of the first and second groups of fast switching valves.

14. The gas distribution system of claim 12, further comprising a flow control section, comprising:

at least one second gas passage adapted to be fluid communication with a first gas line which is in fluid communication with at least one first process gas source;

at least one first valve operable to allow the first process gas to be supplied from the first gas line to at least one second gas passage;

at least one third gas passage adapted to be fluid communication with a second gas line which is in fluid communication with at least one second process gas source; and

at least one second valve operable to allow the second process gas to be supplied from the second gas line to at least one third gas passage.

15. The gas distribution system of claim 14, further comprising a gas supply section including:

the first gas line adapted to be in fluid communication with a plurality of the first process gas sources;

the second gas line adapted to be in fluid communication with a plurality of the second process gas sources;

at least one third valve operable to allow supply of the first process gas to at least one of the first and second gas lines; and

at least one fourth valve operable to allow supply of the second process gas to at least one of the first and second gas lines.

16. The gas distribution system of claim 14, wherein the flow control section includes at least one first flow restrictor and at least one second flow restrictor in fluid communication with the respective second and third gas passages, the first and second flow restrictors being adapted to maintain an approximately constant gas pressure in a region upstream and proximate of the first and second flow restrictors.

17. The gas distribution system of claim 16, wherein the at least one first flow restrictor includes at least two first flow restrictors, the at least one second flow restrictor includes one second flow restrictor, and at least one first flow restrictor has a different flow conductance than the second flow restrictor.

18. The gas distribution system of claim 17, wherein the first flow restrictors have a total flow conductance which is approximately equal to the flow conductance of the second flow restrictor.

19. The gas distribution system of claim 14, wherein the second and third gas passages are adapted to be in fluid communication with at least one tuning gas source which is operable to supply a tuning gas to at least one of the second and third gas passages.

20. The gas distribution system of claim 12, wherein the gas switching section comprises a flow restrictor arranged along each of the first gas passages upstream of a respective fast switching valve, the flow restrictors being adapted to maintain an approximately constant gas pressure in a region of an associated first gas passage upstream of and proximate the flow restrictor.

21. The gas distribution system of claim 12, wherein the fast switching valves can be opened and/or closed within a period of less than about 100 ms, or less than about 50 ms, after receiving a signal.

22. A plasma processing apparatus, comprising:

a plasma processing chamber including a showerhead electrode assembly and having an interior volume of about ½

liter to about 4 liters; and

the gas distribution system according to claim 12 in fluid communication with the plasma processing chamber;

wherein the gas distribution system is operable to substantially replace the first process gas or the second process gas in the plasma confinement zone with the other of the first process gas or second process gas within a period of less than about 1 s, or less than about 200 ms.

23. A method of processing a semiconductor structure in a plasma processing chamber, comprising:

a) supplying a first process gas into the plasma processing chamber while diverting a second process gas to a bypass-line, the plasma processing chamber containing a semiconductor substrate including at least one layer and a patterned resist mask overlying the layer;

b) energizing the first process gas to produce a first plasma and (i) etching at least one feature in the layer or (ii) forming a polymer deposit on the mask;

c) switching the flows of the first and second process gases so that the second process gas is supplied into the plasma processing chamber while diverting the first process gas to the by-pass line, the first process gas being substantially replaced in a plasma confinement zone of the plasma processing chamber by the second process gas within a period of less than about 1 s, or less than about 200 ms;

d) energizing the second process gas to produce a second plasma and (iii) etching the at least one feature in the layer or (iv) forming a polymer deposit on the layer and the mask;

e) switching the flows of the first and second process gases so that the first process gas is supplied into the plasma processing chamber while diverting the second process gas to the by-pass line, the second process gas being substantially replaced in the plasma confinement zone of the plasma processing chamber by the first process gas within a period of less than about 1 s, or less than about 200 ms; and

f) repeating a)-e) a plurality of times with the substrate.

24. The method of claim 23, wherein the polymer deposit is formed to a maximum thickness of less than about 100 angstroms after repeating a)-e) a plurality of times with the substrate.

25. The method of claim 23, wherein the first plasma etches the at least one feature in the layer, and the second plasma forms the deposit on the layer and the mask, the deposit repairing striations in the mask.

26. The method of claim 23, wherein the plasma confinement zone has a volume of about ¹² liter to about 4 liters.

27. The method of claim 23, wherein:

the first layer is of SiO₂;

the mask is a UV-resist mask;

the first process gas comprises a mixture of C₄F₈, O₂ and argon and the first plasma etches the layer; and

the second process gas comprises a mixture of CH₃F, argon and optionally O₂ and the second plasma forms the polymer deposit on the feature and the mask.

28. The method of claim 27, wherein the first process gas is supplied into the plasma processing chamber for a period of about 5 seconds to about 20 seconds, and the second process gas is supplied into the plasma processing chamber for a period of about 1 second to about 3 seconds, each time that the first and second process gases, respectively, are supplied into the plasma processing chamber.

29. The method of claim 23, wherein the plasma processing chamber comprises a showerhead electrode assembly including an inner zone and an outer zone, the first process gas being supplied to the inner zone and the outer zone while the second process gas is diverted to the by-pass line, and the second process gas being supplied to the inner zone and the outer zone while the first process gas is diverted to the by-pass line.

30. The method of claim 29, wherein the first process gas and/or the second process gas is/are supplied to the inner zone and the outer zone at different flow rates.