Perforated shield for plasma immersion ion implantation

• US 6,051,073 A
• Filed: 06/03/1998
• Issued: 04/18/2000
• Est. Priority Date: 02/11/1998
• Status: Expired due to Term

• Current Assignee: Silicon Genesis
• Original Assignee: Silicon Genesis
• Inventors: Chu, Paul K., Chan, Chung
• Primary Examiner(s): DANG, THI D
• Application Number:
  US09/089,883
• Time in Patent Office: 685 Days
• Field of Search: 156/345, 118/723 R, 118/723 E, 250/288
• US Class Current: 438/766
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/32412 Plasma immersion ion implantation
• CPC Class Codes: H01J 37/32623 Mechanical discharge control means

Abstract

A plasma treatment system (200) for implantation with a novel susceptor with a perforated shield (201). The system (200) has a variety of elements such as a chamber in which a plasma is generated in the chamber. The system (200) also has a susceptor disposed in the chamber to support a silicon substrate, which has a surface. The perforated shield (201) draws ions from the implantation toward and through the shield to improve implant uniformity in the substrate. In a specific embodiment, the chamber has a plurality of substantially planar rf transparent windows (26) on a surface of the chamber. The system (200) also has an rf generator (66) and at least two rf sources in other embodiments.

Claims

1. A plasma treatment system for implantation, said system comprising:

a chamber in which a plasma is generated in said chamber;

a susceptor having a susceptor face disposed in said chamber to support a substrate comprising a substrate face; and

a perforated shield disposed adjacent to said susceptor for modifying an electric field for accelerating particles toward said substrate face, said perforated shield tending to linearize electric field lines along said substrate face to create a more uniform distribution of particles to be implanted into a depth of said substrate.

2. The system of claim 1 wherein said chamber comprises a plurality of substantially planar rf transparent windows on a surface of said chamber.

3. The system of claim 1 further comprising:

an rf generator; and

at least two rf sources, each external to said vacuum chamber and each said rf source electrically connected to said rf generator and juxtaposed to a respective one of said plurality rf transparent windows, and operative to generate said plasma in the vacuum chamber;

said rf sources operative to produce a local, substantially uniform plasma proximate said substrate.

4. The system of claim 3 further comprising at least one tuning circuit, each said at least one tuning circuit electrically connected to one of said at least two rf sources.

5. The system of claim 1 wherein said perforated shield is annular in shape and is in parallel alignment with said susceptor face.

6. The system of claim 1 wherein said perforated shield comprises openings occupying at least 80% of an area of said perforated shield.

7. The system of claim 1 wherein said perforated shield comprises openings occupying at least 90% of an area of said perforated shield.

8. The system of claim 1 wherein said susceptor comprises a material selected from stainless steel or aluminum.

9. The system of claim 1 wherein said susceptor is coated with a silicon bearing material, said silicon bearing material being selected from amorphous silicon, polysilicon, or crystalline silicon.

10. The system of claim 1 wherein said system is provided in a cluster tool.

11. The system of claim 1 wherein said system is provided as a stand alone unit.

12. A method for forming a substrate, said method comprising steps of:

providing a substrate onto a face of a susceptor within a plasma immersion ion implantation chamber, said substrate comprising a surface;

introducing particles in a directional manner toward said substrate where a first portion of said particles implant into substrate to uniformly place said ions into a selected depth across a plane of said substrate; and

drawing a second portion of said particles using a perforated shield through said perforated shield disposed adjacent to said face of said susceptor to improve uniformity of said first portion of said particles at said selected.

13. The method of claim 12 wherein said susceptor comprises a material selected from an amorphous silicon, polysilicon, or crystalline silicon.

14. The method of claim 12 wherein said susceptor comprises a base material selected from aluminum or stainless steel.

15. The method of claim 12 wherein said substrate comprises silicon wafer.

16. The method of claim 12 wherein said perforated shield is in parallel alignment with said face of said susceptor.

17. The method of claim 12 wherein said perforated shield comprises openings occupying at least 80% of an area of said perforated shield.

18. The method of claim 12 wherein said perforated shield comprises openings occupying at least 90% of an area of said perforated shield.