Ion implant system having grid assembly

• US 9,741,894 B2
• Filed: 02/25/2016
• Issued: 08/22/2017
• Est. Priority Date: 06/23/2009
• Status: Active Grant

• Current Assignee: Intevac
• Original Assignee: Intevac
• Inventors: Adibi, Babak, Chun, Moon
• Primary Examiner(s): Chin, Edward
• Application Number:
  US15/054,049
• Publication Number:
  US 20160181465A1
• Time in Patent Office: 544 Days
• Field of Search: 118723 R, 20419212, 20419215, 20419217, 20429806, 20429811, 20429816, 20429826, 427569
• CPC Class Codes: C23C 14/042 using masks
• CPC Class Codes: C23C 14/48 Ion implantation
• CPC Class Codes: H01J 2237/0437 Semiconductor substrate
• CPC Class Codes: H01J 2237/184 Vacuum locks
• CPC Class Codes: H01J 2237/201 for mounting multiple objects
• CPC Class Codes: H01J 2237/327 Arrangements for generating the plasma
• CPC Class Codes: H01J 2237/3365 Plasma source implantation
• CPC Class Codes: H01J 37/185 Means for transferring objects between different enclosures of different pressure or atmosphere
• CPC Class Codes: H01J 37/3171 for ion implantation plasma immersion ion implantation H01J37/32412
• CPC Class Codes: H01J 37/32412 Plasma immersion ion implantation
• CPC Class Codes: H01J 37/32422 Arrangement for selecting ions or species in the plasma
• CPC Class Codes: H01L 21/2236 from or into a plasma phase
• CPC Class Codes: H01L 31/068 the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
• CPC Class Codes: H01L 31/0682 back-junction, i.e. rearside emitter, solar cells, e.g. interdigitated base-emitter regions back-junction cells
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/1864 Annealing
• CPC Class Codes: H01L 31/1876 Particular processes or apparatus for batch treatment of the devices
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

An ion implantation system having a grid assembly. The system includes a plasma source configured to provide plasma in a plasma region; a first grid plate having a plurality of apertures configured to allow ions from the plasma region to pass therethrough, wherein the first grid plate is configured to be biased by a power supply; a second grid plate having a plurality of apertures configured to allow the ions to pass therethrough subsequent to the ions passing through the first grid plate, wherein the second grid plate is configured to be biased by a power supply; and a substrate holder configured to support a substrate in a position where the substrate is implanted with the ions subsequent to the ions passing through the second grid plate.

Claims

1. A method for forming solar cells in an implant chamber having a plasma region and implant region defined by a grid assembly, comprising:

differentially pumping the plasma region and the implant region of an implant chamber;

supplying doping gas into the plasma region;

sustaining plasma in the plasma region;

loading wafers onto a conveyor system and placing physical masks in contact with the wafers;

operating the conveyor to deliver the wafer with the masks to the implant region through a plurality of increased vacuum stages, each with increasing level of vacuum leading to the implant region, wherein the implant region having highest level of vacuum, and to remove the wafers from the implant region through a plurality of reduced vacuum stages, each with a decreasing level of vacuum leading away from the implant region;

positioning the wafers with the masks underneath the grid assembly; and

,

implanting the ions through the masks onto unmasked regions of the wafers.

2. The method of claim 1, further comprising adjusting conditions of the plasma to control percentage of each ion species relative to the total ion beam.

3. The method of claim 1, further comprising forming multiple atomic profiles by implanting multiple ion species at different energies.

4. The method of claim 1, comprising implanting multiple wafers simultaneously.

5. The method of claim 1, comprising forming an interdigitated alternate doping regions of n-type and p-type on the wafers.

6. The method of claim 1, comprising simultaneously implanting hydrogen and dopant ions.

7. The method of claim 1, further comprising heating the wafers with the ion beam to cause self-annealing of the wafer.