Method of measuring minority carrier diffusion length and method of manufacturing silicon wafer

• US 7,727,783 B2
• Filed: 04/09/2007
• Issued: 06/01/2010
• Est. Priority Date: 04/11/2006
• Status: Active Grant

• Current Assignee: Sumco Corporation
• Original Assignee: Sumco Corporation
• Inventors: Kubota, Tsuyoshi
• Primary Examiner(s): Lee; Hsien-ming
• Assistant Examiner(s): Parendo; Kevin
• Application Number:
  US11/697,796
• Publication Number:
  US 20070287205A1
• Time in Patent Office: 1,149 Days
• Field of Search: 438/17, 438/788, 438/789, 438/795, 257/E21.531
• US Class Current: 438/17
• CPC Class Codes: G01R 31/2648 Characterising semiconductor materials testing of materials or semi-finished products G01R31/2831; testing during manufacture H01L22/00
• CPC Class Codes: H01L 22/14 for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means

Abstract

A method of measuring a diffusion length of a minority carrier in a silicon wafer by a surface photovoltage method including irradiating the surface-treated silicon wafer with ultraviolet radiation in an oxygen-containing atmosphere, and measuring a diffusion length of a minority carrier in a silicon wafer by a surface photovoltage method.

Claims

1. A method of measuring a diffusion length of a minority carrier in a silicon wafer by a surface photovoltage method comprising:

surface-treating the silicon wafer with hydrofluoric acid;

depositing a carbon-containing compound on the surface of the silicon wafer that has been surface-treated; and

irradiating the surface-treated silicon wafer with ultraviolet radiation wherein said irradiating takes place in an oxygen-containing atmosphere, wherein the silicon wafer after the irradiation with ultraviolet radiation has an oxide film on its surface formed during the irradiation with the ultraviolet radiation; and

measuring the diffusion length of the minority carrier in the silicon wafer by the surface photovoltage method.

2. The method of measuring of claim 1, wherein the oxide film has a thickness ranging from approximately 1 to approximately 3 nm.

3. The method of measuring of claim 1, wherein the ultraviolet radiation has a wavelength ranging from approximately 100 to approximately 380 nm.

4. The method of measuring of claim 1, wherein the ultraviolet radiation has an energy/mol ranging from approximately 100 to approximately 800 kJ/mol.

5. The method of measuring of claim 1, wherein the silicon wafer is a p-type silicon wafer.

6. The method of measuring of claim 1, wherein the silicon wafer is doped with boron and comprises a contaminant metal in the form of iron.

7. The method of measuring of claim 1, wherein an oxygen concentration of the oxygen-containing atmosphere ranges from approximately 5 to approximately 100 volume percent.

8. The method of measuring of claim 1, wherein said surface treatment occurs in the oxygen-containing atmosphere.

9. A method of manufacturing a silicon wafer, comprising:

surface-treating a silicon wafer,

measuring a diffusion length of a minority carrier in the surface-treated silicon wafer by a surface photovoltage method comprising irradiating the surface-treated silicon wafer with ultraviolet radiation in an oxygen-containing atmosphere, wherein the silicon wafer after the irradiation with ultraviolet radiation has an oxide film on its surface formed during the irradiation with the ultraviolet radiation, and measuring the diffusion length of the minority carrier in the silicon wafer,

calculating a concentration of contaminant metal from the measured diffusion length of the minority carrier, and

selecting the silicon wafer of which a concentration of contaminant metal that has been calculated is equal to or less than a target values.