Method of forming a fluorinated silicon oxide layer using plasma chemical vapor deposition

• US 5,571,576 A
• Filed: 02/10/1995
• Issued: 11/05/1996
• Est. Priority Date: 02/10/1995
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Watkins-Johnson
• Inventors: Schmidt, Melvin C., Qian, Lingqian, Nobinger, Glenn L.
• Primary Examiner(s): PIANALTO, BERNARD D
• Application Number:
  US08/386,647
• Time in Patent Office: 634 Days
• Field of Search: 427/99, 427/126.1, 427/574, 427/578, 427/579, 204/192.37, 437/228, 437/238
• US Class Current: 427/574
• CPC Class Codes: C23C 16/401 containing silicon
• CPC Class Codes: C23C 8/28 more than one element being applied in one step
• CPC Class Codes: C23C 8/36 using ionised gases, e.g. ionitriding
• CPC Class Codes: H01L 21/02131 the material being halogen doped silicon oxides, e.g. FSG
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/02205 the layer being characterised by the precursor material for deposition
• CPC Class Codes: H01L 21/02211 the compound being a silane, e.g. disilane, methylsilane or chlorosilane
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/31608 Deposition of SiO2 H01L21/31625, H01L21/31629 and H01L21/31633 take precedence

Abstract

A method of forming a fluorinated silicon oxide dielectric layer by plasma chemical vapor deposition. The method includes the steps of creating a plasma in a plasma chamber and introducing a silicon-containing gas, a fluorine-containing gas, oxygen and an inert gas such that the gases are excited by the plasma and react proximate a substrate to form a fluorinated silicon oxide layer on the surface of the substrate. The fluorinated layer formed has a dielectric constant which is less than that of a silicon oxide layer.

Claims

1. A method of forming a fluorinated silicon oxide layer on the surface of a substrate using a plasma chemical vapor deposition apparatus which includes a process chamber and a plasma chamber, comprising the steps of:

positioning the substrate within said process chamber;

introducing into said plasma chamber an inert gas and oxygen gas, said inert gas being selected from at least one of the inert gases of the group consisting of argon, neon, krypton or xenon;

introducing r.f. power into said plasma chamber such that a plasma is created in the plasma chamber, and wherein the stability of the plasma is enhanced by introduction of said inert gas;

introducing a silicon-containing gas into said process chamber adjacent the surface of said substrate; and

introducing into one of said chambers a fluorine-containing gas whereby said fluorine gas is available at the surface of said substrate, and said silicon-containing gas and said fluorine-containing gas are excited by said plasma and interact proximate to the surface of said substrate to form a fluorinated silicon oxide layer on the surface of said substrate.

2. The method of claim 1 further comprising the step of simultaneously applying an r.f. bias to said substrate during the formation of said fluorinated silicon oxide layer such that the surface of said substrate is sputtered by ions of said inert gas and etched by ions of said fluorine-containing gas to enhance the filling of gaps on the surface of said substrate.

3. The method of claim 1 wherein the flow rate of said oxygen gas is approximately twice the flow rate of each of said silicon and fluorine-containing gases.

4. The method of claim 1 wherein said plasma comprises an ion density of greater than 10¹¹ ions/cm³.

5. The method of claim 1 wherein said fluorine-containing gas is a fluorocarbon represented by the general formula C_n F_2+2n, wherein n is an integer of 1 to 3.

6. The method of claim 5 wherein said fluorocarbon is tetrafluoromethane (CF₄).

7. The method of claim 1 wherein said silicon-containing gas is silane.

8. The method of claim 1 wherein said fluorine-containing gas is silicon tetrafluorine (SiF₄).

9. The method of claim 1 wherein said substrate is maintained at a temperature of not more than 450°

C.; and

said process chamber is maintained at a pressure of not more than 20 mTorr.

10. A method of forming a fluorinated silicon oxide layer on the surface of a substrate using a plasma chemical vapor deposition apparatus which includes a process chamber and a plasma chamber, comprising the steps of:

positioning the substrate within said process chamber;

introducing into said plasma chamber an inert gas and oxygen gas, said inert gas being selected from at least one of the inert gases of the group consisting of argon, neon, krypton and xenon;

introducing r.f. power into said plasma chamber such that a plasma is created in the plasma chamber, said plasma containing an ion density of greater than 10¹¹ ions/cm³ and wherein the stability of the plasma is enhanced by introduction of said inert gas;

maintaining said substrate at a temperature of not more than 450°

C.;

maintaining said process and plasma chambers at a pressure of not more than 20 mTorr;

introducing a silane gas into said process chamber adjacent the surface of said substrate; and

introducing into one of said chambers a fluorine-containing gas, whereby said fluorocarbon gas is available at the surface of said substrate, and said silane gas and said fluorine-containing gas are excited by said plasma and interact proximate to the surface of said substrate to form a fluorinated silicon oxide layer on the surface of said substrate.

11. The method of claim 10 wherein the flow rate of said oxygen gas is approximately twice the flow rate of each of said silicon and fluorine-containing gases.

12. The method of claim 10 further comprising the step of simultaneously applying an r.f. bias to said substrate during the formation of said fluorinated silicon oxide layer such that the surface of said substrate is sputtered by ions of said inert gas etched by and ions of said fluorine-containing gas to enhance the filling of gaps on the surface of said substrate.

13. The method of claim 10 wherein said fluorine-containing gas is tetrafluoromethane (CF₄).

14. The method of claim 10 wherein said fluorine-containing gas is a fluorocarbon represented by the general formula C_n F_2+2n, wherein n is an integer of 1 to 3.

15. The method of claim 10 wherein said fluorine-containing gas is silicon tetrafluorine (SiF₄).

16. A method of forming a fluorinated silicon oxide layer on the surface of a substrate using a plasma chemical vapor deposition apparatus which includes a process chamber and a plasma chamber, comprising the steps of:

positioning the substrate within said process chamber;

introducing into said plasma chamber an inert gas and oxygen gas;

introducing r.f. power into said plasma chamber such that a plasma is created in the plasma chamber, said plasma containing an ion density of greater than 10¹¹ ions/cm³ and wherein the stability of the plasma is enhanced by introduction of said inert gas;

maintaining said substrate at a temperature of not more than 450°

C.;

maintaining said process and plasma chambers at a pressure of not more than 20 Mtorr;

introducing a silane gas into said process chamber adjacent the surface of said substrate; and

introducing silicon tetrafluorine gas into one of said chambers, whereby said silicon tetrafluorine gas is available at the surface of said substrate and said silane gas and said silicon tetrafluorine gas are excited by said plasma and interact proximate to the surface of said substrate to form a fluorinated silicon oxide layer on the surface of said substrate.

17. The method of claim 16 further comprising the step of simultaneously applying an r.f. bias to said substrate during the formation of said fluorinated silicon oxide layer such that the surface of said substrate is sputtered by ions of said inert gas and ions of said fluorine-containing gas to enhance the filling of gaps on the surface of said substrate.

18. A method of forming a fluorinated silicon oxide dielectric layer on the surface of a substrate using a plasma chemical vapor deposition apparatus which includes a process chamber and a plasma chamber, comprising the steps of:

positioning the substrate within said process chamber;

introducing into said plasma chamber argon and oxygen gas, said inert gas being selected from at least one of the inert gases of the group consisting of argon, neon, krypton and xenon;

introducing r.f. power into said plasma chamber such that a plasma is created in the plasma chamber, said plasma containing an ion density of greater than 10¹¹ ions/cm³ and wherein the stability of the plasma is enhanced by introduction of said inert gas;

maintaining said substrate at a temperature of not more than 450°

C.;

maintaining said process and plasma chambers at a pressure of not more than 20 Mtorr;

introducing a silane gas into said process chamber adjacent the surface of said substrate; and

introducing tetrafluoromethane gas into one of said chambers, whereby said tetrafluoromethane gas is available at the surface of said substrate, and said silane gas and said tetrafluoromethane gas are excited by said plasma and interact proximate to the surface of said substrate to form a fluorinated silicon oxide layer on the surface of said substrate.

19. The method of claim 18 further comprising the step of simultaneously applying an r.f. bias to said substrate during the formation of said fluorinated silicon oxide layer such that the surface of said substrate is sputtered by ions of said argon gas and etched by ions of said fluorine-containing gas to enhance the filling of gaps on the surface of said substrate.