Laser chips attached to a photonics chip by multiple adhesives
Structures including a photonics chip and a surface-mounted laser chip, and methods of forming same. The structure comprises a photonics chip including a surface, a laser chip including a light output and a body that are spaced from the surface of the photonics chip, a first adhesive between the body of the laser chip and the surface of the photonics chip, and a second adhesive between the body of the laser chip and the surface of the photonics chip. The light output is oriented toward the surface of the photonics chip, the first adhesive has a first thermal conductivity, the second adhesive has a second thermal conductivity that is less than the first thermal conductivity of the first adhesive, and the second adhesive is disposed in a light path between the light output of the laser chip and the surface of the photonics chip.
1 . A structure comprising:
a photonics chip including a surface and a grating coupler;
a laser chip including a light output and a body that are spaced from the surface of the photonics chip, the body of the laser chip including a surface;
a first adhesive between the surface of the body of the laser chip and the surface of the photonics chip, the first adhesive having a first thermal conductivity, and the first adhesive including a first section and a second section; and
a second adhesive between the surface of the body of the laser chip and the surface of the photonics chip, the second adhesive having a second thermal conductivity that is less than the first thermal conductivity of the first adhesive, the second adhesive positioned in a lateral direction between the first section and the second section of the first adhesive, and the second adhesive disposed in a light path between the light output of the laser chip and the surface of the photonics chip,
wherein the laser chip is configured to emit light from the light output that propagates in the light path through the second adhesive toward the grating coupler.
2 . The structure of claim 1 wherein the first adhesive and the second adhesive each extend fully from the surface of the photonics chip to the surface of the body of the laser chip.
3 . The structure of claim 1 wherein the first adhesive and the second adhesive each contact the surface of the photonics chip, and the first adhesive and the second adhesive each contact the surface of the body of the laser chip.
4 . The structure of claim 1 wherein the second thermal conductivity is greater than or equal to 0.2 W/m-K.
5 . The structure of claim 1 wherein the second adhesive comprises an organic binder and a plurality of particles in the organic binder.
6 . The structure of claim 5 wherein the plurality of particles comprise a metal.
7 . The structure of claim 1 wherein the laser chip is a vertical-cavity surface-emitting laser.
8 . The structure of claim 1 wherein the first section of the first adhesive contacts the second adhesive, and the second section of the first adhesive contacts the second adhesive.
9 . The structure of claim 1 wherein the first section of the first adhesive has a first thickness, and the second section of the first adhesive has a second thickness that is greater than the first thickness.
10 . The structure of claim 9 wherein the photonics chip includes a back-end-of-line stack having a first bond pad and a second bond pad that are disposed at the surface of the photonics chip, the first adhesive and the second adhesive are arranged between the first bond pad and the second bond pad, the first section of the first adhesive is adjacent to the first bond pad, and the second section of the first adhesive is adjacent to the second bond pad.
11 . The structure of claim 10 wherein the laser chip includes a first contact and a second contact, and further comprising:
a wire bond that couples the first contact to the first bond pad; and
a solder bump that couples the second contact to the second bond pad.
12 . The structure of claim 1 wherein the first section of the first adhesive has a first thickness, and the second section of the first adhesive has a second thickness that is equal to the first thickness.
13 . The structure of claim 12 wherein the photonics chip includes a back-end-of-line stack having a first bond pad and a second bond pad that are disposed at the surface of the photonics chip, the first adhesive and the second adhesive are arranged between the first bond pad and the second bond pad, the first section of the first adhesive is adjacent to the first bond pad, and the second section of the first adhesive is adjacent to the second bond pad.
14 . The structure of claim 13 wherein the laser chip includes a first contact and a second contact, and further comprising:
a first wire bond that couples the first contact to the first bond pad; and
a second wire bond that couples the second contact to the second bond pad.
15 . The structure of claim 13 wherein the laser chip includes a first contact and a second contact, and further comprising:
a first solder bump that couples the first contact to the first bond pad; and
a second solder bump that couples the second contact to the second bond pad.
16 . The structure of claim 1 wherein the surface is inclined at an angle relative to the surface of the photonics chip.
17 . The structure of claim 16 wherein the angle is 10°.
18 . The structure of claim 1 wherein the first section of the first adhesive is wedge-shaped, and the second section of the first adhesive is wedge-shaped.
19 . A method comprising:
forming a first adhesive on a surface of a photonics chip, wherein the first adhesive has a first thermal conductivity, and the first adhesive includes a first section and a second section;
placing a laser chip including a light output and a body that are spaced from the surface of the photonics chip, wherein the body of the laser chip includes a surface, and the first adhesive is disposed between the surface of the body of the laser chip and the surface of the photonics chip; and
forming a second adhesive between the surface of the body of the laser chip and the surface of the photonics chip, wherein the second adhesive has a second thermal conductivity that is less than the first thermal conductivity of the first adhesive, the second adhesive is positioned in a lateral direction between the first section and the second section of the first adhesive, and the second adhesive is disposed in a light path between the light output of the laser chip and the surface of the photonics chip,
wherein the photonics chip includes a grating coupler, and the laser chip is configured to emit light from the light output that propagates in the light path through the second adhesive toward the grating coupler.