H-3 silicon carbide PN-type radioisotopic battery and manufacturing method of the same

Abstract

The present invention discloses an H-3 silicon carbide PN-type radioisotopic battery and a manufacturing method therefor. The radioisotopic battery has a structure including, from bottom to top, an N-type ohmic contact electrode, an N-type highly doped SiC substrate, an N-type SiC epitaxial layer, and a P-type SiC epitaxial layer. A P-type SiC ohmic contact doped layer is disposed on a partial upper area of the P-type SiC epitaxial layer, a P-type ohmic contact electrode is disposed on top of the P-type SiC ohmic contact doped layer, a SiO.sub.2 passivation layer is disposed on an upper area of the P-type SiC epitaxial layer where the P-type ohmic contact doped layer is removed, and an H-3 radioisotope source is provided on the top of the SiO.sub.2 passivation layer.

Claims

1. An H-3 silicon carbide PN-type radioisotopic battery, comprising: an N-type conductive SiC substrate; an N-type SiC epitaxial layer; a P-type SiC epitaxial layer; a SiO.sub.2 passivation layer; a P-type SiC ohmic contact doped region; a P-type ohmic contact electrode; an N-type ohmic contact electrode; and an H-3 radioisotope source, wherein the N-type ohmic contact electrode is disposed under the substrate, the N-type SiC epitaxial layer is disposed on the substrate, the P-type SiC epitaxial layer is disposed on the N-type SiC epitaxial layer, the P-type SiC ohmic contact doped region and the SiO.sub.2 passivation layer are adjacent to each other and are both disposed on an upper surface of the P-type SiC epitaxial layer, the P-type ohmic contact electrode is disposed right above the P-type SiC ohmic contact doped region, and the H-3 radioisotope source is disposed right above the SiO.sub.2 passivation layer.

2. The H-3 silicon carbide PN-type radioisotopic battery according to claim 1, wherein a total thickness of the N-type SiC epitaxial layer and the P-type SiC epitaxial layer ranges from 0.8 μm to 2.0 μm.

3. The H-3 silicon carbide PN-type radioisotopic battery according to claim 1, wherein a thickness of the P-type SiC epitaxial layer ranges from 0.05 μm to 0.20 μm.

4. The H-3 silicon carbide PN-type radioisotopic battery according to claim 3, wherein the P-type SiC epitaxial layer has a doping concentration in a range of 1×10.sup.14 cm.sup.−3 to 1×10.sup.17 cm.sup.−3.

5. The H-3 silicon carbide PN-type radioisotopic battery according to claim 2, wherein the N-type SiC epitaxial layer has a doping concentration in a range of 1×10.sup.17 cm.sup.−3 to 1×10.sup.18 cm.sup.−3.

6. The H-3 silicon carbide PN-type radioisotopic battery according to claim 1, wherein the P-type SiC ohmic contact doped region has a doping concentration in a range of 5×10.sup.18 cm.sup.−3 to 2×10.sup.19 cm.sup.−3 and a thickness in a range of 0.20 μm to 0.50 μm.

7. The H-3 silicon carbide PN-type radioisotopic battery according to claim 1, wherein a thickness of the SiO.sub.2 passivation layer ranges from 5 nm to 20 nm.

8. A manufacturing method for the H-3 silicon carbide PN-type radioisotopic battery according to claim 1, comprising: Step 1: providing the substrate formed by an N-type doped SiC substrate; Step 2: epitaxially growing the N-type SiC epitaxial layer on an upper surface of the substrate provided in Step 1 through chemical vapor deposition, wherein the N-type SiC epitaxial layer has a doping concentration of 1×10.sup.17 cm.sup.−3 to 1×10.sup.18 cm.sup.−3 and a thickness of 0.75 μm to 1.8 μm; Step 3: epitaxially growing the P-type SiC epitaxial layer on an upper surface of the N-type SiC epitaxial layer through chemical vapor deposition, wherein the P-type SiC epitaxial layer has a doping concentration of 1×10.sup.14 cm.sup.−3 to 1×10.sup.17 cm.sup.−3 and a thickness of 0.05 μm to 0.20 μm; Step 4: epitaxially growing the P-type SiC ohmic contact doped region on an upper surface of the P-type SiC epitaxial layer through chemical vapor deposition, wherein the P-type SiC ohmic contact doped region has a doping concentration of 5×10.sup.18 cm.sup.−3 to 2×10.sup.19 cm.sup.−3 and a thickness of 0.2 μm to 0.5 μm; Step 5: etching away a part of the P-type SiC ohmic contact doped region through reactive ion etching to expose the P-type SiC epitaxial layer; Step 6: forming an oxidation layer on a surface of the P-type SiC ohmic contact doped region and a surface of the P-type SiC epitaxial layer through dry-oxygen oxidation, and removing the oxidation layer through wet etching; Step 7: forming the SiO.sub.2 passivation layer on a region of an upper surface of the P-type SiC epitaxial layer outside the P-type SiC ohmic contact doped region through dry-oxygen oxidation, wherein the SiO.sub.2 passivation layer has a thickness of 5 nm to 20 nm; Step 8: sequentially depositing metal Ni with a thickness of 200 nm to 400 nm and metal Pt with a thickness of 100 nm to 200 nm on the P-type SiC ohmic contact doped region; Step 9: sequentially depositing metal Ni with a thickness of 200 nm to 400 nm and metal Pt with a thickness of 100 to 200 nm under the substrate; Step 10: performing thermal annealing under N.sub.2 atmosphere at a temperature of 950° C. to 1050° C. for 2 minutes to form the P-type ohmic contact electrode on the P-type SiC ohmic contact doped region and to form the N-type ohmic contact electrode under the substrate; and Step 11: providing the H-3 radioisotope source on a top of the SiO.sub.2 passivation layer.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a front view of an H-3 silicon carbide PN-type radioisotopic battery according to the present invention.

(2) FIG. 2 is a flow diagram of a manufacturing method of an H-3 silicon carbide PN-type radioisotopic battery according to the present invention.

(3) FIG. 3 is a diagram of the prior art.

REFERENCE SIGNS IN FIGURES

(4) 1—N-type doped SiC substrate; 2—N-type SiC epitaxial layer; 3—P-type SiC epitaxial layer; 4—SiO.sub.2 passivation layer; 5—P-type SiC ohmic contact doped region; 6—P-type ohmic contact electrode; 7—N-type ohmic contact electrode; and 8—H-3 radioisotope source.

DESCRIPTION OF EMBODIMENTS

(5) The present inventions are further described with reference to the drawings.

(6) Referring to FIG. 1 and FIG. 2, an H-3 silicon carbide PN-type radioisotopic battery includes an N-type conductive SiC substrate 1, an N-type SiC epitaxial layer 2, a P-type SiC epitaxial layer 3, a SiO.sub.2 passivation layer 4, a P-type SiC ohmic contact doped region 5, a P-type ohmic contact electrode 6, an N-type ohmic contact electrode 7, and an H-3 radioisotope source 8. The N-type ohmic contact electrode 7 is disposed under the substrate 1, the N-type SiC epitaxial layer 2 is disposed on the substrate, the P-type SiC epitaxial layer 3 is disposed on the N-type SiC epitaxial layer 2, the P-type SiC ohmic contact doped region 5 and the SiO.sub.2 passivation layer 4 are adjacent to each other and are both disposed on an upper surface of the P-type SiC epitaxial layer 3, the P-type ohmic contact electrode 6 is disposed right above the P-type SiC ohmic contact doped region 5, and the H-3 radioisotope source 8 is disposed right above the SiO.sub.2 passivation layer 4.

(7) A total thickness of the N-type SiC epitaxial layer 2 and the P-type SiC epitaxial layer 3 ranges from 0.8 μm to 2.0 μm.

(8) A thickness of the P-type SiC epitaxial layer 3 ranges from 0.05 μm to 0.20 μm.

(9) The P-type SiC epitaxial layer 3 has a doping concentration in a range of 1×10.sup.14 cm.sup.−3 to 1×10.sup.17 cm.sup.−3. The thickness of the P-type SiC epitaxial layer 3 is decreased with the increase of the concentration of the P-type SiC epitaxial layer 3, and the thickness of the P-type SiC epitaxial layer 3 is increased with a decrease of the concentration of the P-type SiC epitaxial layer 3.

(10) The N-type SiC epitaxial layer 2 has a doping concentration in a range of 1×10.sup.17 cm.sup.−3 to 1×10.sup.18 cm.sup.−3. The thickness of the N-type SiC epitaxial layer 2 is decreased with an increase of the concentration of the N-type SiC epitaxial layer 2.

(11) The P-type SiC ohmic contact doped region 5 has a doping concentration in a range of 5×10.sup.18 cm.sup.−3 to 2×10.sup.19 cm.sup.−3 and a thickness in a range of 0.20 μm to 0.50 μm.

(12) A thickness of the SiO.sub.2 passivation layer 4 ranges from 5 nm to 20 nm.

(13) A manufacturing method for the H-3 silicon carbide PN-type radioisotopic battery includes the following steps:

(14) Step 1: providing the substrate 1 formed by an N-type doped SiC substrate;

(15) Step 2: epitaxially growing the N-type SiC epitaxial layer 2 on an upper surface of the substrate provided in Step 1 through chemical vapor deposition, the N-type SiC epitaxial layer 2 having a doping concentration of 1×10.sup.17 cm.sup.−3 to 1×10.sup.18 cm.sup.−3 and a thickness of 0.75 μm to 1.8 μm;

(16) Step 3: epitaxially growing the P-type SiC epitaxial layer 3 on an upper surface of the N-type SiC epitaxial layer 2 through chemical vapor deposition, the P-type SiC epitaxial layer 3 having a doping concentration of 1×10.sup.14 cm.sup.−3 to 1×10.sup.17 cm.sup.−3 and a thickness of 0.05 μm to 0.20 μm;

(17) Step 4: epitaxially growing the P-type SiC ohmic contact doped region 5 on an upper surface of the P-type SiC epitaxial layer 3 through chemical vapor deposition, the P-type SiC ohmic contact doped region 5 having a doping concentration of 5×10.sup.18 cm.sup.−3 to 2×10.sup.19 cm.sup.−3 and a thickness of 0.2 μm to 0.5 μm;

(18) Step 5: etching away a part of the P-type SiC ohmic contact doped region 5 through reactive ion etching to expose the P-type SiC epitaxial layer 3;

(19) Step 6: forming an oxidation layer on a surface of the P-type SiC ohmic contact doped region 5 and a surface of the P-type SiC epitaxial layer 3 through dry-oxygen oxidation, and removing the oxidation layer through wet etching;

(20) Step 7: forming the SiO.sub.2 passivation layer 4 on a region of an upper surface of the P-type SiC epitaxial layer 3 outside the P-type SiC ohmic contact doped region 5 through dry-oxygen oxidation, the SiO.sub.2 passivation layer 4 having a thickness of 5 nm to 20 nm;

(21) Step 8: sequentially depositing metal Ni with a thickness of 200 nm to 400 nm and metal Pt with a thickness of 100 nm to 200 nm on the P-type SiC ohmic contact doped region 5;

(22) Step 9: sequentially depositing metal Ni with a thickness of 200 nm to 400 nm and metal Pt with a thickness of 100 nm to 200 nm under the substrate 1;

(23) Step 10: performing thermal annealing under N.sub.2 atmosphere at a temperature of 950° C. to 1050° C. for 2 minutes to form the P-type ohmic contact electrode 6 on the P-type SiC ohmic contact doped region. 5 and to form the N-type ohmic contact electrode 7 under the substrate 1; and

(24) Step 11: providing the H-3 radioisotope source 8 on a top of the SiO.sub.2 passivation layer 4.

EXAMPLE 1

(25) A manufacturing method of an H-3 silicon carbide PN-type radioisotopic battery includes the following steps:

(26) Step 1: providing a substrate 1 formed by an N-type doped SiC substrate;

(27) Step 2: epitaxially growing an N-type SiC epitaxial layer 2 on an upper surface of the substrate provided in Step 1 through chemical vapor deposition, the N-type SiC epitaxial layer 2 having a doping concentration of 4×10.sup.17 cm.sup.−3 and a thickness of 1.8 μm;

(28) Step 3: epitaxially growing a P-type SiC epitaxial layer 3 on an upper surface of the N-type SiC epitaxial layer 2 through chemical vapor deposition, the P-type SiC epitaxial layer 3 having a doping concentration of 3×10.sup.16 cm.sup.−3 and a thickness of 0.10 μm;

(29) Step 4: epitaxially growing a P-type SiC ohmic contact doped region 5 on an upper surface of the P-type SiC epitaxial layer 3 through chemical vapor deposition, the P-type SiC ohmic contact doped region 5 having a doping concentration of 1×10.sup.19 cm.sup.−3 and a thickness of 0.2 μm;

(30) Step 5: etching away a part of the P-type SiC ohmic contact doped region 5 through reactive ion etching to expose the P-type SiC epitaxial layer 3;

(31) Step 6: forming an oxidation layer on a surface of the P-type SiC ohmic contact doped region 5 and a surface of the P-type SiC epitaxial layer 3 through dry-oxygen oxidation, and removing the oxidation layer through wet etching;

(32) Step 7: forming a SiO.sub.2 passivation layer 4 on a region of an upper surface of the P-type SiC epitaxial layer 3 outside the P-type SiC ohmic contact doped region 5, the SiO.sub.2 passivation layer 4 having a thickness of 10 nm;

(33) Step 8: sequentially depositing metal Ni with a thickness of 400 nm and metal Pt with a thickness of 200 nm on the P-type SiC ohmic contact doped region 5;

(34) Step 9: sequentially depositing metal Ni with a thickness of 400 nm and metal Pt with a thickness of 200 nm under the substrate 1;

(35) Step 10: performing thermal annealing under N.sub.2 atmosphere at a temperature of 1000° C. for 2 minutes to form a P-type ohmic contact electrode 6 on the P-type SiC ohmic contact doped region 5 and to form an N-type ohmic contact electrode 7 under the substrate 1; and

(36) Step 11: providing an H-3 radioisotope source 8 on a top of the SiO.sub.2 passivation layer 4.