VCSEL having a self-aligned heat sink and method of making

• US 5,654,228 A
• Filed: 03/17/1995
• Issued: 08/05/1997
• Est. Priority Date: 03/17/1995
• Status: Expired due to Term

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Lungo, John, Shieh, Chan-Long, Lebby, Michael S.
• Primary Examiner(s): KUNEMUND, ROBERT M
• Application Number:
  US08/407,061
• Time in Patent Office: 872 Days
• Field of Search: 437/129, 437/209, 437/211, 148/DIG. 95
• US Class Current: 438/32
• CPC Class Codes: H01S 2301/176 Specific passivation layers on surfaces other than the emission facet
• CPC Class Codes: H01S 5/02476 Heat spreaders, i.e. improving heat flow between laser chip and heat dissipating elements
• CPC Class Codes: H01S 5/04254 characterised by the shape
• CPC Class Codes: H01S 5/18344 characterized by the mesa, e.g. dimensions or shape of the mesa
• CPC Class Codes: H01S 5/2081 using special etching techniques

Abstract

A substrate (102) having a surface (103) with a first stack of distributed Bragg reflectors (106), a first cladding region (107), an active region (108), a second cladding region (109), a second stack of distributed Bragg reflectors (110), and a contact region (111) is provided. A mesa (131) with a surface (133) and a trench (136) is formed. A first dielectric layer (122) is formed overlying substrate (102) and covering a portion of trench (136). A second dielectric layer (128) is formed on surface (133) of mesa (131). A seed layer (126) having a pattern is formed, with the pattern of seed layer (126) having an opening on a portion of second dielectric layer (128) of mesa (131). A metal is selectively plated on seed layer (126), thereby generating a layer (204) on seed layer (126) for removal of heat from VCSEL (101).

Claims

1. A method for making a VCSEL with a self-aligned integrated heat sink comprising the steps of:

providing a substrate having a surface with a first stack of distributed Bragg reflectors, a first cladding region, an active region, a second cladding region, a second stack of distributed Bragg reflectors, and a contact region;

forming a first dielectric layer on said contact region;

forming a mesa with a surface and a trench, wherein said trench extends from said first dielectric layer into a portion of said second stack of distributed Bragg reflectors, and wherein said trench is adjacent to a portion of said mesa;

forming a second dielectric layer overlying said substrate so that a portion of said second dielectric layer covers a portion of said trench while exposing a portion of said contact region on said mesa;

forming a conductive layer on said second dielectric layer and on said mesa;

forming a seed layer on said conductive layer;

forming a dielectric area on said seed layer above said surface of said mesa; and

plating a metal selectively on said seed layer generating a layer on said seed layer for removal of heat, thereby generating an integrated heat sink.

2. A method for making a VCSEL with a self-aligned integrated heat sink as claimed in claim 1 where, in the step of providing a substrate having a surface with a first stack of distributed Bragg reflectors, a first cladding region, an active region, a second cladding region, a second stack of distributed Bragg reflectors, and a contact region, the contact region is provided by including depositing a titanium/tungsten layer.

3. A method for making a VCSEL with a self-aligned integrated heat sink as claimed in claim 1 where, in the step of forming a mesa with a surface and a trench, said mesa with said surface and said trench are formed by a dry etch process.

4. A method for making a VCSEL with a self-aligned integrated heat sink as claimed in claim 1 where, in the step of forming a seed layer, the seed layer is formed by a deposition process.

5. A method for making a VCSEL with a self-aligned integrated heat sink as claimed in claim 1 where, prior to the step of forming a second dielectric layer overlying said substrate and covering a portion of said trench, the step of forming a current confinement region in said trench is performed.

6. A method for making a VCSEL with a self-aligned integrated heat sink as claimed in claim 5 where, in the step of forming a current confinement region, the current confinement region is fabricated by changing structural integrity of a portion of the second stack of the distributed Bragg reflectors.

7. A method for making a VCSEL with a self-aligned integrated heat sink as claimed in claim 5 where, in the step of forming a current confinement region, the current confinement region is fabricated by ion implantation.

8. A method for making a VCSEL having a heat sink comprising the steps of:

forming a partially fabricated VCSEL having a mesa with a surface and a trench adjacent to the mesa, the surface of the mesa being centrally located;

forming a seed layer in the trench and on the mesa;

forming a dielectric area on the surface of the mesa; and

plating a second metal selectively on the seed layer, thereby generating a VCSEL.

9. A method for making a VCSEL having a heat sink as claimed in claim 8 where, in the step of forming a seed layer in the trench and on the mesa, the seed layer is formed by depositing gold material.

10. A method for making a VCSEL having a heat sink as claimed in claim 8 where, in the step of forming a seed layer in the trench and on the mesa, the seed layer is formed by sputtering.

11. A method for making a VCSEL having a heat sink as claimed in claim 8 where, in the step of plating a second metal selectively on the seed layer, the second metal selectively plated is gold.

12. A method for making a VCSEL having a heat sink as claimed in claim 8 where, in the step of forming a partially fabricated VCSEL having a mesa with a surface and a trench adjacent to the mesa, a step of forming a current confinement region is included.

13. A method for making a VCSEL having a heat sink as claimed in claim 12 where, in the step of forming a current confinement region, the current confinement region is fabricated by changing structural integrity of a portion of the trench.

14. A method for making a VCSEL having a heat sink as claimed in claim 12 where, in the step of forming a current confinement region, the current confinement region is fabricated by ion implantation.

15. A method for making a VCSEL having auto-aligned heat sink comprising the steps of:

providing a substrate having a surface with a first stack of distributed Bragg reflectors, a first cladding region, an active region, a second cladding region, a second stack of distributed Bragg reflectors, and a contact region;

forming a layer on the contact region;

forming a masking layer having a ring shaped pattern on the layer, the ring shaped pattern of the masking layer exposes portions of the layer, while covering other portions of the layer;

etching the exposed portions of the layer, thereby removing exposed portions of the layer and exposing portions of the contact region;

etching the exposed portions of the contact region and into a portion of the second stack of distributed Bragg reflectors to form a mesa, thereby forming a trench adjacent to the mesa;

forming a dielectric layer overlying portions of the contact region and covering a portion of the trench;

forming a seed layer overlying the substrate;

forming a dielectric area on the seed layer; and

plating a second metal selectively on the seed layer, thereby selectively plating the second metal on the seed layer and exposing a portion of the dielectric area.

16. A method for making a VCSEL having auto-aligned heat sink as claimed in claim 15 wherein after the step of plating the second metal on the seed layer, the portion of the dielectric area exposed is etched to expose a portion of the contact region, thereby generating a VCSEL.

17. A method for sizing an emission hole of a VCSEL comprising the steps of:

providing a substrate having a surface with a first stack of distributed Bragg reflectors, a first cladding region, an active region, a second cladding region, a second stack of distributed Bragg reflectors, and a contact region;

forming a first dielectric layer on said contact region;

forming a mesa with a surface and a trench, wherein said trench extends from said first dielectric layer into a portion of said second stack of distributed Bragg reflectors, and wherein said trench is adjacent to a portion of said mesa;

forming a second dielectric layer overlying said substrate so that a portion of said second dielectric layer covers a portion of said trench while exposing a portion of said contact region on said mesa;

forming a conductive layer on said second dielectric layer and on said mesa;

forming a seed layer on said conductive layer;

forming a dielectric area on said seed layer above said surface of said mesa; and

plating a metal selectively on said seed layer generating a layer on said seed layer, as well as generating portions that encroach on the dielectric area, thereby sizing an emission hole of the VCSEL.