Collection devices for plasma immersion ion implantation

• US 6,269,765 B1
• Filed: 10/01/1998
• Issued: 08/07/2001
• 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): Mills, Gregory
• Assistant Examiner(s): Zervigon, Rudy
• Application Number:
  US09/165,231
• Time in Patent Office: 1,041 Days
• Field of Search: 118/723.I, 204/298.06, 204/192.12, 204/192.19, 156/345
• US Class Current: 118/723.00I
• CPC Class Codes: C23C 14/48 Ion implantation
• CPC Class Codes: C23C 14/568 Transferring the substrates through a series of coating stations C23C14/562 takes precedence
• 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 37/32697 Electrostatic control

Abstract

A plasma treatment system (200) for implantation with a novel susceptor with a perforated shield (201) and collection devices (221). 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. The collection device accumulates charge that can detrimentally influence the substrate during processing. 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;

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

a perforated shield disposed adjacent to and coplanar with 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; and

a collection device disposed underlying said perforated shield to collect particles that traverse through said perforated shield, said collection device being at a potential to attract said particles without substantially influencing said linearized electric field, said collection device also preventing a portion of said particles from depositing onto said substrate face.

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 collection device is disposed on a portion of said susceptor.

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

9. A plasma treatment system provided in a cluster tool for implantation, said system comprising:

a chamber in which a plasma is generated;

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

a perforated shield disposed adjacent to and coplanar with 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; and

a collection device disposed underlying said perforated shield to collect particles that traverse through said perforated shield, said collection device being at a potential to attract said particles without substantially influencing said linearized electric field, said collection device also preventing a portion of said particles from depositing onto said substrate face, wherein said collection device is biased using a magnitude that is less than a biasing potential between said plasma and said susceptor.

10. A plasma treatment system provided in a cluster tool for implantation, said system comprising:

a chamber in which a plasma is generated;

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

a perforated shield disposed adjacent to and coplanar with 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; and

a collection device disposed underlying said perforated shield to collect particles that traverse through said perforated shield, said collection device being at a potential to attract said particles without substantially influencing said linearized electric field, said collection device also preventing a portion of said particles from depositing onto said substrate face, wherein said collection device is biased using a magnitude that is less than a biasing potential between said plasma and said susceptor.

12. A method for forming a substrate, said method comprising a method for measuring a distribution of implanted particles, said measuring method comprising:

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 selectively place said ions into a selected depth across a plane of said substrate;

drawing a second portion of said particles using a perforated shield through said perforated shield disposed adjacent to and coplanar with said face of said susceptor to improve uniformity of said first portion of said particles at said selected depth; and

collecting a portion of said second portion of said particles using a plurality of collection devices surrounding said substrate; and

measuring an electric current from each of said collection devices, said measuring providing a plurality of measured electric current values.

13. The method of claim 12 further comprising comparing said measured current values from said respective collection devices against a reference value to determine if said uniformity is within a predefined limit.

14. The method of claim 12 wherein said predefined limit is a unformity variation of less than one percent.

15. The method of claim 12 wherein said substrate is a production wafer.