Device and method for producing chlorine trifluoride and system for etching semiconductor substrates using this device

• US 8,382,940 B2
• Filed: 03/27/2003
• Issued: 02/26/2013
• Est. Priority Date: 06/28/2002
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Laermer, Franz
• Primary Examiner(s): DHINGRA, RAKESH KUMAR
• Application Number:
  US10/519,724
• Publication Number:
  US 20060006057A1
• Time in Patent Office: 3,624 Days
• Field of Search: 118/723.I, 118/723.MW, 118/723.ME, 216/67, 438/710, 156/345.48, 156/345.35, 156/345.36, 156/345.41
• US Class Current: 156/345.35
• CPC Class Codes: B01J 19/088 giving rise to electric discharges for heating purposes H05B7/00; for the production of ozone C01B13/11, H01T19/00
• CPC Class Codes: B01J 2219/0894 Processes carried out in the presence of a plasma
• CPC Class Codes: C01B 7/24 Inter-halogen compounds
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence
• CPC Class Codes: H05H 1/4652 using inductive coupling means, e.g. coils

Abstract

A device (6) and a method for generating chlorine trifluoride is described, a high-density plasma (105) being generated in the interior of a plasma reactor (100) using plasma generating means (110, 120, 130, 150, 155, 160, 170, 180), and a first gas and a second gas, which react with one another under the influence of the high-density plasma (105) in the plasma reactor (100) under the formation of chlorine trifluoride, being supplied to the plasma reactor (100) via gas supply means (21, 22, 25, 26). In addition, a gas outlet (20) is provided, via which the generated chlorine trifluoride can be removed from the plasma reactor (100). Finally, a system (5) for etching semiconductor substrates (30), silicon wafers in particular, is described including such an upstream device (6), the system (5) having a process chamber (10) which is connected to the plasma reactor (100) via the gas outlet (20), and the semiconductor substrate (30) being situated in the process chamber (10) and exposed to the gaseous chlorine trifluoride generated by the device (6).

Claims

1. A device for generating chlorine trifluoride comprising:

a plasma reactor (100);

plasma generating means (110, 120, 130, 150, 155, 160, 170, 180) via which a high-density plasma (105) can be generated in the interior of the plasma reactor (100);

a first gas;

a second gas selected to react with the first gas to form chlorine trifluoride when under the influence of a high-density plasma; and

gas supply means (21, 25, 22, 26) via which the first gas and the second gas can be supplied to the plasma reactor (100), these gases reacting with one another under the influence of the high-density plasma (105) in the plasma reactor (100), forming chlorine trifluoride, and a gas outlet (20) via which the formed chlorine trifluoride can be removed from the plasma reactor (100), the gas supply means including

a first mass flow regulator configured to regulate the first gas to a first flow rate to the plasma reactor, and

a second mass flow regulator configured to regulate the second gas to a second flow rate to the plasma reactor,

wherein the first flow regulator and the second flow regulator are configured to regulate the respective first and second flow rates to provide an ideal stoichiometric conversion of the first gas and the second gas to chlorine trifluoride.

2. The device according to claim 1, wherein the plasma generating means include a coil (110), an adaptation network (120), and a high-frequency generator (130).

3. The device according to claim 1, wherein the plasma generating means include a microwave hollow conductor (150), tuning elements (155), a magnetron (170), a circulator (160), and a hollow conductor terminating element (180).

4. The device according to claim 1, wherein the plasma reactor (100) includes a quartz tube or a hollow quartz body having a polished interior wall or a ceramic tube or a hollow ceramic body having a polished interior wall or being made of aluminum oxide.

5. The device according to claim 1, wherein first mass flow regulator (22) is adjustable, and the second mass flow regulator (26) is adjustable.

6. A system for etching semiconductor substrates, comprising:

the device (6) according to claim 1, a process chamber (10), which is connected to the plasma reactor (100) via the gas outlet (20), being assigned to it, the semiconductor substrate (30) being situated in the process chamber (10) and being exposed to the gaseous chlorine trifluoride generated by the device (6) for generating chlorine trifluoride.

7. A method for generating chlorine trifluoride, comprising:

generating a high-density plasma (105) in a plasma reactor (100), and supplying to the plasma reactor (100) a first gas and a second gas, which react with one another under the influence of the high-density plasma (105) in the plasma reactor (100), forming chlorine trifluoride, a ratio of the amount of the first gas and the amount of the second gas being selected to achieve an ideal stoichiometric conversion to chlorine trifluoride.

8. The method according to claim 7, wherein the high-density plasma (105) is generated using inductive high-frequency excitation or microwave excitation.

9. The method according to claim 7, wherein a gas which includes Cl₂ or HCl is used as the first gas, and a gas which includes NF₃, F₂, SF₆ is used as the second gas.

10. The method according to claim 7, wherein oxygen as an additional gas is supplied to the plasma reactor (100) or to a process chamber (10) downstream from the plasma reactor (100).

11. The method according to claim 7, wherein the generated chlorine trifluoride is separated from hydrogen fluoride and other gas components, using a filter downstream from the plasma reactor (100).

12. The method according to claim 7, wherein the first gas and the second gas are supplied to the plasma reactor (100) in such a way that fluoride atoms and chlorine atoms, in the form of radicals or reactive species, are present in the high-density plasma (105) at a 3:

1 ratio.

13. The method according to claim 7, wherein the high-density plasma (105) is generated having a density in radicals or reactive species of at least 10¹¹ particles per cm³, in particular at least 10¹² particles per cm³.

14. A method of generating chlorine trifluoride, comprising:

generating a high-density plasma in a plasma reactor;

supplying to the plasma reactor a first gas according to a first gas flow rate; and

supplying to the plasma reactor a second gas according to a second gas flow rate, wherein

the first gas and the second gas react with one another under the influence of the high-density plasma to form chlorine trifluoride in the plasma reactor, and

a ratio of the first gas flow to the second gas flow is selected to achieve an ideal stoichiometric conversion to chlorine trifluoride.

15. The method of claim 14, further comprising:

supplying the chlorine trifluoride gas from the plasma reactor to a process chamber, wherein a gas flow of the chlorine trifluoride from the plasma reactor to the process chamber is greater than 100 sccm.

16. A method comprising:

generating a high-density plasma in a plasma reactor;

supplying to the plasma reactor a first gas; and

supplying to the plasma reactor a second gas;

reacting the first gas and the second gas under the influence of the high-density plasma to form chlorine trifluoride in the plasma reactor; and

transferring the formed chlorine trifluoride to a process chamber assigned to the plasma reactor;

etching a silicone substrate in the process chamber using the formed chlorine trifluoride as an etching gas.

17. The method of claim 16, wherein:

the first gas is supplied to the plasma reactor according to a first gas flow rate;

the second gas is supplied to the plasma reactor according to a second gas flow rate; and

a ratio of the first gas flow to the second gas flow is selected to achieve an ideal stoichiometric conversion to chlorine trifluoride.

18. The method of claim 16, wherein a gas flow of the chlorine trifluoride from the plasma reactor to the process chamber is greater than 100 sccm.