Method of producing semiconductor device with heat dissipation metal layer and metal projections

• US 6,245,596 B1
• Filed: 10/27/1999
• Issued: 06/12/2001
• Est. Priority Date: 03/19/1998
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Matsuoka, Hiroshi, Kosaki, Katsuya, Tamaki, Masahiro
• Primary Examiner(s): Lee, Eddie C.
• Assistant Examiner(s): DIAZ, JOSE R
• Application Number:
  US09/427,584
• Time in Patent Office: 594 Days
• Field of Search: 438/122, 438/114, 438/113, 438/463, 438/462, 438/464, 438/465, 257/712, 257/720
• US Class Current: 438/114
• 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
• CPC Class Codes: H01L 23/3677 Wire-like or pin-like cooling fins or heat sinks
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A method of producing a semiconductor device having a heat dissipating metal layer wherein the number of patterning steps is reduced, laser dicing produces a better profile, and first and second metal layers are prevented from separating from each other, and a semiconductor device produced by the method. The number of patterning steps is reduced by employing a flat exposure step for photoresist with mask alignment. A better appearance is obtained by forming the metal layers which connect the semiconductor devices with each other from a first metal layer having a lower melting point and a second metal layer having a higher melting point and severing the first metal layer and the second metal layer successively, from the first metal layer side. A second metal layer is prevented from peeling by preventing oxidation of the plated feeder layer through plating of the second metal layer.

Claims

1. A method of producing a semiconductor device comprising:

forming a first separation groove in a semiconductor substrate at a front surface of the semiconductor substrate;

depositing a first metal layer in the first separation groove on the semiconductor substrate;

thinning the semiconductor substrate from a back surface of the semiconductor substrate;

forming a heat dissipating metal layer on the back surface of the semiconductor substrate except on a part of the back surface opposite the first separation groove;

using the heat dissipating metal layer as a mask, etching a second separation groove in the back surface of the semiconductor substrate, exposing the first metal layer;

depositing a second metal layer in the second separation groove on the first metal layer, wherein the melting point of the second metal layer is higher than the melting point of the first metal layer; and

successively severing the first metal layer and the second metal layer by means of laser light wherein the first metal layer and the second metal layer have a reflectivity of no more than 80% for the laser light.

2. The method as claimed in claim 1, including:

forming the second metal layer in the second separation groove and on the heat dissipating metal layer;

applying a photoresist covering the second metal layer and filling the second separation groove;

removing a portion of the photoresist, leaving the photoresist filling the second separation groove;

removing the second metal layer from the heat dissipating metal layer, using the photoresist filling the second separation groove as a mask, so that the second metal layer is left in the second separation groove; and

removing all photoresist.

3. The method as claimed in claim 1, wherein the first metal layer and the second metal layer reflect more than 8% of the laser light in laser severing.

4. The method as claimed in claim 1, wherein the first metal layer is a Ni alloy selected from the group consisting of Ni—

P, Ni—

B, and Ni—

B—

W, and the second metal layer is one of Ni and Cr.

5. A method of producing a semiconductor device including:

forming a first separation groove in a semiconductor substrate at a front surface of the semiconductor substrate;

depositing a first metal layer in the first separation groove on the semiconductor substrate;

thinning the semiconductor substrate from a back surface of the semiconductor substrate;

forming a heat dissipating metal layer on the back surface of the semiconductor substrate except on a part of the back surface opposite the first separation groove;

using the heat dissipating metal layer as a mask, etching a second separation groove in the back surface of the semiconductor substrate, exposing the first metal layer;

depositing a second metal layer in the second separation groove on the first metal layer;

forming a film of Ti and a film of Au successively, covering the second metal layer and the heat dissipating metal layer; and

successively severing the first metal layer and the second metal layer by means of laser light wherein the first metal layer and the second metal layer have a reflectivity of no more than 80% for the laser light.

6. A method of producing a semiconductor device including:

forming a first separation groove in a semiconductor substrate at a front surface of the semiconductor substrate;

depositing a first metal layer in the first separation groove on the semiconductor substrate;

thinning the semiconductor substrate from a back surface of the semiconductor substrate;

forming a heat dissipating metal layer on the back surface of the semiconductor substrate except on a part of the back surface opposite the first separation groove;

using the heat dissipating metal layer as a mask, etching a second separation groove in the back surface of the semiconductor substrate, exposing the first metal layer;

plating a feeder layer and an Au film in at least the second separation groove;

depositing a second metal layer on the Au film, using the feeder layer, by electrolytic plating, in the second separation groove, wherein the feeder layer is a Ni alloy selected from the group consisting of Ni—

P, Ni—

B, and Ni—

B—

W, and

successively severing the first metal layer and the second metal layer by means of laser light wherein the first metal layer and the second metal layer have a reflectivity of no more than 80% for the laser light.

7. The method as claimed in claim 6, wherein the thickness of the Au film is from 500 to 5000 Å

.

8. The method as claimed in claim 6, wherein the thickness of the Au film is from 500 to 1000 Å

.

9. The method as claimed in claim 6, wherein the first metal layer is a Ni alloy selected from the group consisting of Ni—

P, Ni—

B, and Ni—

B—

W, and the second metal layer is one of Ni and Cr.