# US 9,040,345 B2 · Laser ablation technique for electrical contact to buried electrically conducting layers in diamond

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- Number: US 9,040,345 B2
- Document ID: US9040345B2
- Status: Granted
- Kind: B2
- Application number: 13/801,495
- Filed: 2013-03-13
- Published: 2013-09-26
- Granted: 2015-05-26
- Earliest claimed: 2012-03-20
- Assignees: The United States of America as represented by the Secretary of the Navy
- Applicants: Bradford B. Pate; Matthew P. Ray; Jeffrey W. Baldwin
- Inventors: Bradford B. Pate; Matthew P. Ray; Jeffrey W. Baldwin
- Web page: https://patentgrep.com/patent/US9040345B2

## CPC

- H05K 1/09: Use of materials for the {conductive, e.g. } metallic pattern
- B23K 26/06: Shaping the laser beam, e.g. by masks or multi-focusing
- B23K 26/0622: by shaping pulses
- B23K 26/361: for deburring or mechanical trimming (B23K26/351 takes precedence)
- B23K 26/362: Laser etching
- B23K 26/40: taking account of the properties of the material involved
- B23K 26/402: involving non-metallic material, e.g. isolators
- B23K 26/53: for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks
- C30B 29/04: Diamond
- C30B 33/02: Heat treatment (C30B33/04, C30B33/06 take precedence)
- H05K 3/4602: {characterized by a special circuit board as base or central core whereon additional circuit layers are built or additional circuit boards are laminated}
- H10D 62/8325: {Silicon carbide}
- B23K 2101/38: Conductors
- B23K 2101/40: Semiconductor devices
- B23K 2103/50: {Inorganic materials other than metals or composite materials}
- H05K 3/0029: {of inorganic insulating material}
- H05K 2201/0323: Carbon
- H10D 62/8303: {Diamond}
- H10W 40/254: {Diamond}
- Y10S 438/931: Silicon carbide semiconductor
- Y10T 428/265: 1 mil or less
- Y10T 428/30: Self-sustaining carbon mass or layer with impregnant or other layer
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method of laser ablation for electrical contact to a buried electrically conducting layer in diamond comprising polishing a single crystal diamond substrate having a first carbon surface, implanting the diamond with a beam of 180 KeV followed by 150 KeV C+ ions at fluencies of 4×1015 ions/cm2 and 5×1015 ions/cm2 respectively, forming an electrically conducting carbon layer beneath the first carbon surface, and ablating the single crystal diamond which lies between the electrically conducting layer and the first carbon surface.

## Claims

### Claim 1

A method of laser ablation for electrical contact to a buried electrically conducting layer in diamond comprising:
polishing a single crystal diamond substrate having a first carbon surface;
implanting the diamond with a beam of 180 KeV followed by 150 KeV C+ ions at fluencies of 4×1015 ions/cm2 and 5×1015 ions/cm2 respectively;
forming an electrically conducting carbon layer beneath the first carbon surface; and
ablating the single crystal diamond which lies between the electrically conducting layer and the first carbon surface.

### Claim 2 (depends on 1)

The method of claim 1 wherein the step of ablating uses a diode pumped tripled Nd:YAG laser at 355 nm and wherein the laser pulse duration is about 35 ns with a pulse frequency of 10 kHz.

### Claim 3 (depends on 2)

The method of claim 2 further including the step of focusing the Nd:YAG laser about 0.5 mm above the first carbon surface.

### Claim 4 (depends on 3)

The method of claim 3 further including the step of defocusing to an about 9 μm diameter beam spot laser output pulses of 17 μJ.

### Claim 5 (depends on 4)

The method of claim 4 wherein the implanting occurs at 7 degrees to the C(100) axis;
wherein the electrically conducting carbon layer is about 50 nm beneath the first carbon surface; and
wherein the electrically conducting carbon layer is about 200 nm thick.

### Claim 6 (depends on 5)

The method of claim 5 further including the step of ensuring no damage at the first carbon surface.

### Claim 7 (depends on 6)

The method of claim 6 further including the step of making electrical contact to the electrically conducting carbon layer.

### Claim 8

A method of laser ablation for electrical contact to a buried electrically conducting layer in diamond comprising:
polishing a single crystal diamond substrate having a first carbon surface;
implanting the diamond with a beam of 180 KeV followed by 150 KeV C+ ions at fluencies of 4×1015 ions/cm2 and 5×1015 ions/cm2 respectively;
forming an electrically conducting carbon layer beneath the first carbon surface;
utilizing a diode pumped tripled Nd:YAG laser at 355 nm wherein the laser pulse duration is about 35 ns with a pulse frequency of 10 kHz;
focusing the Nd:YAG laser about 0.5 mm above the first carbon surface;
preventing damage at the first carbon surface; and
ablating the single crystal diamond which lies between the electrically conducting layer and the first carbon surface.

### Claim 9 (depends on 8)

The method of claim 8 further including the step of making electrical contact to the electrically conducting carbon layer.