Film formation method and apparatus for forming silicon oxide film

• US 20080081104A1
• Filed: 09/25/2007
• Published: 04/03/2008
• Est. Priority Date: 09/28/2006
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Fujita, Takehiko, Ishida, Yoshihiro, Hasebe, Kazuhide, Ogawa, Jun, Nakajima, Shigeru
• Granted Patent: US 7,906,168 B2
• Time in Patent Office: Days
• US Class Current: 427/58
• CPC Class Codes: C23C 16/402 Silicon dioxide
• CPC Class Codes: C23C 16/45542 Plasma being used non-continuously during the ALD reactions
• CPC Class Codes: C23C 16/45546 specially adapted for a substrate stack in the ALD reactor
• CPC Class Codes: C23C 16/509 using internal electrodes
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/02222 the compound being a silazane
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/0228 deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD

Abstract

An oxide film is formed on a target substrate by CVD, in a process field to be selectively supplied with a first process gas including a silicon source gas and a second process gas including an oxidizing gas. The oxide film is formed by performing cycles each alternately including first and second steps. The first step performs supply of the first process gas, thereby forming an adsorption layer containing silicon on a surface of the target substrate. The second performs supply of the second process gas, thereby oxidizing the adsorption layer on the surface of the target substrate. The silicon source gas is a univalent or bivalent aminosilane gas, and each of the cycles is arranged to use a process temperature lower than that used for a trivalent aminosilane gas.

Claims

1. A film formation method for a semiconductor process for forming an oxide film on a target substrate by CVD, in a process field configured to be selectively supplied with a first process gas comprising a silicon source gas and a second process gas comprising an oxidizing gas, the method being arranged to perform a plurality of cycles to laminate thin films respectively formed by the cycles, thereby forming the oxide film with a predetermined thickness, each of the cycles alternately comprising:

a first step of performing supply of the first process gas to the process field while stopping supply of the second process gas to the process field, thereby forming an adsorption layer containing silicon on a surface of the target substrate; and

a second step of performing supply of the second process gas to the process field while stopping supply of the first process gas to the process field, thereby oxidizing the adsorption layer on the surface of the target substrate,

wherein the silicon source gas is a univalent or bivalent aminosilane gas, and each of the cycles is arranged to use a process temperature lower than that used for a trivalent aminosilane gas.

2. The method according to claim 1, wherein the method further comprises determining the process temperature to set a film formation rate within a reference range, before starting the cycles.

3. The method according to claim 2, wherein the process temperature is preset at a value lowered by that much corresponding to an increase in reactivity on the surface of the target substrate, which is provided by use of a univalent or bivalent aminosilane gas as the silicon source gas, so that the film formation rate falls within the reference range.

4. The method according to claim 1, wherein the silicon source gas is a univalent aminosilane gas.

5. The method according to claim 4, wherein the aminosilane gas is selected from the group consisting of SiH₃NC₂(CH₃)₄, SiH₃(NHC(CH₃)₃), and SiH₃(N(CH₃)₂).

6. The method according to claim 1, wherein the silicon source gas is a bivalent aminosilane gas.

7. The method according to claim 6, wherein the aminosilane gas is selected from the group consisting of bistertialbutylaminosilane, bisdiethylaminosilane, and bisdimethylaminosilane.

8. The method according to claim 1, wherein the oxidizing gas is selected from the group consisting of oxygen, ozone, nitrogen oxide, nitrogen dioxide, dinitrogen oxide, and water vapor.

9. The method according to claim 1, wherein each of the cycles is arranged to set the process field at a temperature of 25 to 200°

C., and the second step comprises an excitation period of supplying the second process gas to the process field while exciting the second process gas by an exciting mechanism, thereby generating radicals of the oxidizing gas and oxidizing the adsorption layer on the surface of the target substrate by use of the radicals.

10. The method according to claim 9, wherein the oxidizing gas is oxygen.

11. The method according to claim 10, wherein each of the cycles is arranged to set the process field at a temperature of 100°

C. or less.

12. The method according to claim 1, wherein each of the cycles is arranged to set the process field at a temperature of 200°

C. to 600°

C.

13. The method according to claim 12, wherein the oxidizing gas is selected from the group consisting of oxygen, ozone, and water vapor.

14. The method according to claim 1, wherein each of the cycles further comprises an intermediate step of exhausting gas from the process field while stopping supply of the first and second process gases to the process field, between the second step thereof and the first step of a next cycle.

15. The method according to claim 14, wherein each of the cycles further comprises an intermediate step of exhausting gas from the process field while stopping supply of the first and second process gases to the process field, between the first and second steps.

16. The method according to claim 14, wherein each of the cycles is arranged to exhaust gas from the process field continuously through the cycle.

17. The method according to claim 16, wherein the intermediate step comprises a period of supplying an inactive gas to the process field.

18. The method according to claim 1, wherein the process field is configured to accommodate a plurality of target substrates at intervals in a vertical direction, and the target substrates are heated by a heater disposed around the process field.

19. A film formation apparatus for a semiconductor process, comprising:

a process container having a process field configured to accommodate a target substrate;

a support member configured to support the target substrate inside the process field;

a heater configured to heat the target substrate inside the process field;

an exhaust system configured to exhaust gas from inside the process field;

a first process gas supply circuit configured to supply a first process gas comprising a silicon source gas to the process field;

a second process gas supply circuit configured to supply a second process gas comprising an oxidizing gas to the process field;

an exciting mechanism configured to selectively excite the second process gas to be supplied to the process field; and

a control section configured to control an operation of the apparatus,

wherein, in order to form an oxide film on the target substrate by CVD, the control section performs a plurality of cycles to laminate thin films respectively formed by the cycles, thereby forming the oxide film with a predetermined thickness, each of the cycles alternately comprising

a first step of performing supply of the first process gas to the process field while stopping supply of the second process gas to the process field, thereby forming an adsorption layer containing silicon on a surface of the target substrate, and

a second step of performing supply of the second process gas to the process field while stopping supply of the first process gas to the process field, thereby oxidizing the adsorption layer on the surface of the target substrate,

wherein the silicon source gas is a univalent or bivalent aminosilane gas, and each of the cycles is arranged to use a process temperature lower than that used for a trivalent aminosilane gas.

20. A computer readable medium containing program instructions for execution on a processor, which is used for a film formation apparatus for a semiconductor process for forming an oxide film on a target substrate by CVD, in a process field configured to be selectively supplied with a first process gas comprising a silicon source gas and a second process gas comprising an oxidizing gas, wherein the program instructions, when executed by the processor, control the film formation apparatus to perform a plurality of cycles to laminate thin films respectively formed by the cycles, thereby forming the oxide film with a predetermined thickness, each of the cycles alternately comprising:

a first step of performing supply of the first process gas to the process field while stopping supply of the second process gas to the process field, thereby forming an adsorption layer containing silicon on a surface of the target substrate; and

a second step of performing supply of the second process gas to the process field while stopping supply of the first process gas to the process field, thereby oxidizing the adsorption layer on the surface of the target substrate,

wherein the silicon source gas is a univalent or bivalent aminosilane gas, and each of the cycles is arranged to use a process temperature lower than that used for a trivalent aminosilane gas.