Silicon carbide and method of manufacturing the same

• US 20020019117A1
• Filed: 08/09/2001
• Published: 02/14/2002
• Est. Priority Date: 08/10/2000
• Status: Abandoned Application

• Current Assignee: Hoya Corporation
• Original Assignee: Hoya Corporation
• Inventors: Nagasawa, Hiroyuki
• Application Number:
  US09/924,872
• Publication Number:
  US 20020019117A1
• Time in Patent Office: Days
• US Class Current: 438/505
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/36 Carbides
• CPC Class Codes: H01L 21/0445 the devices having semiconductor bodies comprising crystalline silicon carbide multistep processes for the manufacture of said devices H01L29/66053

Abstract

In a method of manufacturing a silicon carbide substance, such as a film, a layer, a semiconductor, which is doped with an impurity, a carbonization process is executed after formation of a doped silicon substance which is obtained by carrying out a silicon deposition process and by a doping process of the impurity. Both the silicon deposition and the doping processes may be simultaneously or separately carried out prior to the carbonization process or may be continued during the carbonization process also. At any rate, the carbonization process is intermittently carried out. A unit process of composed of a combination of the silicon deposition process, the doping process, and the carbonization process may be repeated a plurality times, for example, 2000 times.

Claims

1. A method of depositing a silicon carbide on a substrate from a vapor phase or a liquid phase, comprising the steps of:

depositing a silicon layer on the substrate;

doping the silicon layer with an impurity composed of at least one element selected from a group consisting of N, B, Al, Ga, In, P, As, Sb, Se, Zn, O, Au, V, Er, Ge, and Fe, to form a doped silicon layer; and

carbonizing the doped silicon layer into a silicon carbide layer of the silicon carbide doped with the impurity.

2. A method as claimed in claim 1, wherein the silicon layer depositing step, the doping step, and the carbonizing step are carried out during epitaxially growing a thin film on the substrate by the use of a chemical vapor deposition technique;

the silicon layer deposition step being carried out by using a gas of a silane group or a dichlorosilane group as a silicon raw material while the carbonizing step is carried out by the use of an unsaturated carbohydrate gas.

3. A method as claimed in claim 1, wherein the silicon layer depositing step is followed by the doping step and the carbonizing step is carried out after the doping step.

4. A method as claimed in claim 1, wherein the silicon layer depositing step and the doping step are simultaneously carried out and are followed by the carbonizing step.

5. A method as claimed in claim 1, wherein the silicon layer depositing step and the doping step are simultaneously carried out while the carbonizing step is carried out when a predetermined time lapses after the start of both the silicon depositing and the doping steps.

6. A method as claimed in claim 1, wherein the silicon carbide layer doped with the impurity is deposited to a desired thickness by repeating a process unit composed of the silicon depositing step, the doping step, and the carbonizing step a plurality of times.

7. A method as claimed in claim 6, wherein an amount of impurity is varied during each doping step of the unit processes to provide a plurality of silicon carbide layers which have different impurity concentrations in a thickness direction, respectively.

8. A method as claimed in claim 1, wherein the doping step controls an amount of impurity so that impurity concentrations in the silicon carbide fall within a range between 1×

10¹³/cm³ to 1×

10²¹/cm³.

9. A method as claimed in claim 1, wherein the doping step controls an amount of impurity so that an impurity concentration gradient falls within a range between 10×

10¹⁸/cm⁴ and 4×

10²⁴/cm⁴ in a thickness direction of the silicon carbide layer.

10. A method as claimed in claim 1, wherein the substrate has a surface which is structured by either one of a single crystal silicon, a silicon carbide of a cubic system, and a silicon carbide of a hexagonal system while the silicon carbide layer deposited on the surface of the substrate is structured by silicon carbide of a cubic system or a hexagonal system.

11. A method as claimed in claim 1, further comprising the step of:

removing the substrate from the silicon carbide layer after the formation of the doped silicon carbide, to leave a silicon carbide wafer.

12. A method as claimed in claim 6, wherein the doping step of each process unit is carried out by varying a species of the impurities from one to another at each process unit to provide a pn junction in the doped silicon carbide layer.

13. A method as claimed in claim 1, further comprising the step of:

using, as a seed crystal, the doped silicon carbide obtained in claim 1;

and

further growing a silicon carbide on the seed crystal by a vapor deposition method, a sublimation re-crystallization method, or a liquid deposition method.

15. A semiconductor device having the silicon carbide manufactured by the method claimed in claim 1.

16. A semiconductor device structured by the silicon carbide claimed in claim 14.

18. A method as claimed in claim 17, further comprising the step of preparing an undoped silicon prior to the doping step.

19. A method as claimed in claim 17, wherein the impurity is composed of at least one element selected from a group consisting of N, B, Al, Ga, In, P, As, Sb, Se, Zn, O, Au, V, Er, Ge, and Fe.

14. A silicon carbide having a region which has an impurity concentration gradient between 1×

10²²/cm⁴ and 4×

10²⁴/cm⁴ in the thickness direction.

17. A method of depositing a silicon carbide doped with an impurity, comprising the steps of:

doping the impurity into a silicon to form a doped silicon; and

carbonizing, after the doping, the doped silicon into the silicon carbide.