Transfer die for micro-transfer printing with non-conductive isolation layer and isolation trench
A method of manufacturing a transfer die for use in a transfer print process. The manufactured transfer die comprises a semiconductor device suitable for bonding to a silicon-on-insulator wafer. The method comprises the steps of providing a non-conductive isolation region in a semiconductor stack, the semiconductor stack comprising a sacrificial layer above a substrate; and etching an isolation trench into the semiconductor stack from an upper surface thereof, such that the isolation trench extends only to a region of the semiconductor stack above the sacrificial layer. The isolation trench and the non-conductive isolation region together separate a bond pad from a waveguide region in the optoelectronic device.
1 . A method of manufacturing a transfer die, the transfer die comprising an optoelectronic device suitable for bonding to a silicon-based platform via a transfer print process, the method comprising the steps of:
providing a non-conductive isolation layer in a semiconductor stack, the semiconductor stack comprising:
a sacrificial layer above a substrate,
the non-conductive isolation layer directly above the sacrificial layer,
a first doped layer, doped with a first dopant species, above the non-conductive isolation layer, and
a second doped layer, doped with a second dopant species different from the first dopant species;
etching an isolation trench into the semiconductor stack from an upper surface thereof only to the non-conductive isolation layer, wherein the isolation trench and the non-conductive isolation layer together separate, and electrically isolate, a bond pad from a waveguide region in the optoelectronic device;
etching a contact trench into the semiconductor stack to the first doped layer;
forming a first electrical contact on the first doped layer in the contact trench; and
forming a second electrical contact on the second doped layer, the second electrical contact extending over the isolation trench from a first portion of the second doped layer in the bond pad to a second portion of the second doped layer in the waveguide region.
2 . The method of claim 1 , wherein the non-conductive isolation layer is an iron-doped layer in the semiconductor stack.
3 . The method of claim 1 , wherein the non-conductive isolation layer is created in the semiconductor stack by implantation.
4 . The method of claim 3 , wherein the implanted non-conductive isolation layer extends from a bottom of the etched isolation trench to the sacrificial layer.
5 . The method of claim 1 , further comprising the step of:
providing a Benzocyclobutene, BCB, fill in the isolation trench.
6 . The method of claim 1 , further comprising the step of:
epitaxially growing an iron-doped material in the isolation trench from the non-conductive isolation layer.
7 . The method of claim 1 , further comprising the step of:
epitaxially growing an iron-doped material from the non-conductive isolation layer to form the bond pad.
8 . The method of claim 1 , wherein the semiconductor stack comprises an optically active layer between the first doped layer and the second doped layer.
9 . The method of claim 1 , further comprising the step of:
etching away the sacrificial layer to form an undercut region which spaces the optoelectronic device from the substrate.
10 . A transfer die, comprising an optoelectronic device and a substrate, the optoelectronic device being suitable for bonding to a silicon-based platform via a transfer print process,
wherein the optoelectronic device comprises:
a semiconductor stack, comprising:
a non-conductive isolation layer above the substrate,
a first doped layer, doped with a first dopant species, above the non-conductive isolation layer, and
a second doped layer, doped with a second dopant species different from the first dopant species;
a waveguide region in a first portion of the semiconductor stack and for guiding light through the optoelectronic device;
a bond pad in a second portion of the semiconductor stack and for providing an electrical connection to the optoelectronic device;
an isolation trench in the semiconductor stack and extending from an upper surface thereof only to the non-conductive isolation layer, wherein the isolation trench and the non-conductive isolation layer together separate, and electrically isolate, the bond pad from the waveguide region;
a contact trench in the semiconductor stack and extending from the upper surface thereof to the first doped layer;
a first electrical contact on the first doped layer in the contact trench; and
a second electrical contact on the second doped layer, the second electrical contact extending over the isolation trench from a first portion of the second doped layer in the bond pad to a second portion of the second doped layer in the waveguide region.
11 . The transfer die of claim 10 , wherein the non-conductive isolation layer is an iron-doped isolation layer.
12 . The transfer die of claim 10 , wherein the isolation trench contains an iron-doped material.
13 . The transfer die of claim 10 , wherein the bond pad comprises an iron-doped material.
14 . The transfer die of claim 10 , wherein the non-conductive isolation layer is an ion-implantation isolation region.
15 . The transfer die of claim 10 , wherein the semiconductor stack further comprises a sacrificial layer above the substrate, and the non-conductive isolation layer is directly above the sacrificial layer.