Method for separating chips from diamond wafer

• US 20030127428A1
• Filed: 05/13/2002
• Published: 07/10/2003
• Est. Priority Date: 09/14/2000
• Status: Active Grant

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Saka, Toshiaki, Fujii, Satoshi, Uemura, Tomoki, Gotou, Noboru, Itakura, Katsuhiro
• Granted Patent: US 6,805,808 B2
• Time in Patent Office: Days
• US Class Current: 216/65
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/172 wherein at least one of the layers is non-metallic
• CPC Class Codes: B23K 2103/30 Organic material
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/364 for making a groove or trench, e.g. for scribing a break initiation groove
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: H01L 21/78 with subsequent division of the substrate into plural individual devices cutting to change the surface-physical characteristics or shape of semiconductor bodies H01L21/304

Abstract

A method for separating chips from a diamond wafer comprising a substrate, a chemically vapor-deposited diamond layer, and microelectronic elements, with the microelectronic elements protected from thermal damage and degradation caused by the thermally decomposed cuttings produced during the processing steps. (1) Front-side grooves 6 are formed on the chemically vapor-deposited diamond layer 2 by laser processing using a laser such as a YAG, CO₂, or excimer laser each having a large output so that the grooves 6 can have a depth 1/100 to 1.5 times the thickness of the diamond layer. (2) The thermally decomposed cuttings produced during the laser processing are removed by using a plasma. (3) Back-side grooves 9 are formed on the substrate 1 by dicing such that the back-side grooves 9 are in alignment with the front-side grooves 6. (4) The diamond wafer 4 is divided into individual chips 10 by applying mechanical stresses.

Claims

1. A method for separating chips from a diamond wafer, the diamond wafer comprising:

(a) a substrate;

(b) one of a polycrystalline chemically vapor-deposited diamond layer and a single-crystalline chemically vapor-deposited diamond layer each formed on the substrate; and

(c) a plurality of microelectronic elements formed on the chemically vapor-deposited diamond layer;

the method comprising the steps of;

(1) forming front-side grooves on the chemically vapor-deposited diamond layer by laser processing, the front-side grooves having a depth {fraction (1/100)} to 1.5 times the thickness of the chemically vapor-deposited diamond layer;

(2) removing by a plasma the thermally decomposed cuttings produced during the laser processing;

(3) forming back-side grooves on the substrate by dicing the substrate with a diamond saw blade such that the back-side grooves are in alignment with the front-side grooves; and

(4) breaking the diamond wafer by applying mechanical stresses to separate chips each having a single microelectronic element.

2. A method as defined in claim 1, wherein when the depth of the laser processing of the chemically vapor-deposited diamond layer is less than the thickness of the chemically vapor-deposited diamond layer, the gas for producing the plasma for removing the thermally decomposed cuttings is oxygen.

3. A method as defined in claim 1, wherein when the depth of the laser processing of the chemically vapor-deposited diamond layer is at least the thickness of the chemically vapor-deposited diamond layer and when the substrate is made of one of Si or SiC, the gas for producing the plasma for removing the thermally decomposed cuttings is a gas selected from the group consisting of:

(a) oxygen;

(b) one of the CF-family gases that are CF₄, C₂F₆, CHF₃, and C₄F₈; and

(c) a mixed gas of oxygen and one of the CF-family gases.

4. A method as defined in claim 1, wherein when the depth of the laser processing of the chemically vapor-deposited diamond layer is at least the thickness of the chemically vapor-deposited diamond layer and when the substrate is made of one of sapphire, AlN, or GaAs, the gas for producing the plasma for removing the thermally decomposed cuttings is a gas selected from the group consisting of:

(a) one of the CH-family gases that are CH₄ and C₂H₆; and

(b) one of the Cl-containing gases that are BCl₃ and CCl₄.

5. A method as defined in claim 1, wherein the laser for the laser processing is one of a YAG laser, a CO₂ laser, or an excimer laser each producing a laser lightwave having a wavelength of 250 to 1,120 nm.

6. A method as defined in claim 1, wherein the depth of the back-side grooves formed on the substrate by dicing the substrate with a diamond saw blade is such that the remaining thickness of the substrate is at most 100 μ

m.