Fabricating photonics devices fully integrated into a CMOS manufacturing process
Disclosed are process enhancements to fully integrate the processing of a photonics device into a CMOS manufacturing process flow. A CMOS wafer may be divided into different portions. One of the portions is for the CMOS devices and one or more other portions are for the photonics devices. The photonics devices include a ridged waveguide and a germanium photodetector. The germanium photodetector may utilize a seeded crystallization from melt process so there is more flexibility in the processing of the germanium photodetector.
1. A method of incorporating a photonics device into a CMOS manufacturing process flow comprising:
providing a semiconductor substrate wherein the semiconductor substrate is a semiconductor on insulator substrate comprising a semiconductor material layer on a buried oxide layer;
processing a first portion of the semiconductor substrate to form a CMOS device according to a CMOS manufacturing process flow; and
processing a second portion of the semiconductor substrate according to a process flow for a photonics device comprising:
patterning a semiconductor material layer in the semiconductor substrate to form first trenches between first pillars of semiconductor material;
filling the first trenches with an insulator material;
depositing a dielectric material over the second portion;
opening a window in the dielectric material to expose an underlying first pillar of semiconductor material;
depositing a layer of germanium over the first and second portions including over the dielectric material;
depositing a first insulating layer over the germanium layer;
patterning the germanium layer and first insulating layer over the second portion and removing the germanium layer and first insulating layer from the first portion;
depositing a nitride layer over the germanium layer and first insulating layer so as to encapsulate the germanium layer and first insulating layer;
opening the first insulating layer and the nitride layer to form an opening;
depositing an oxide material over the first and second portions and in the opening; and
depositing a metallic material to make contact with the germanium layer.
2. The method of claim 1 wherein the photonics device is a germanium photodetector.
3. The method of claim 1 wherein processing a first portion of the semiconductor substrate comprises:
patterning the semiconductor material layer in the semiconductor substrate to form second trenches between second pillars of semiconductor material;
filling the second trenches with an insulator material;
well and Vt implanting;
forming a gate structure;
forming source and drain implants; and
forming contacts.
4. The method of claim 3 wherein processing of the second portion further comprises a crystallization anneal to crystallize the germanium layer by a seeded crystallization from melt process.
5. The method of claim 1 further comprising processing a third portion of the semiconductor substrate according to a process flow for a second photonics device comprising:
patterning a semiconductor material layer in the semiconductor substrate to form first trenches between first pillars of semiconductor material;
filling the first trenches with an insulator material;
low dose implanting at least one of the first pillars to form a pn or p-i-n junction; and
high dose implanting at least one of the first pillars to form a low resistance contact.
6. The method of claim 5 wherein the photonics device is a germanium photodetector and the second photonics device is a waveguide.
7. A method of incorporating a photonics device into a CMOS manufacturing process flow comprising:
providing a semiconductor substrate;
processing a first portion of the semiconductor substrate to form a CMOS device according to a CMOS manufacturing process flow;
processing a second portion of the semiconductor substrate according to a process flow for a photonics device comprising:
patterning a semiconductor material layer in the semiconductor substrate to form first trenches between first pillars of semiconductor material;
filling the first trenches with an insulator material;
low dose implanting at least one of the first pillars to form a pn or p-i-n junction;
high dose implanting at least another one of the first pillars to form a low resistance contact; and
processing a third portion of the semiconductor substrate according to a process flow for a photonics device comprising:
patterning a semiconductor material layer in the semiconductor substrate to form second trenches between second pillars of semiconductor material;
filling the second trenches with an insulator material;
depositing a dielectric material over the third portion;
opening a window in the dielectric material to expose an underlying second pillar of semiconductor material;
depositing a layer of germanium over the first and third portions including over the dielectric material;
depositing a first insulating layer over the germanium layer;
patterning the germanium layer and first insulating layer over the third portion and removing the germanium layer and first insulating layer from the first portion; and
depositing a nitride layer over the germanium layer and first insulating layer so as to encapsulate the germanium layer and first insulating layer;
opening the first insulating layer and the nitride layer to form an opening;
depositing an oxide material over the first, second and third portions and in the opening; and
depositing a metallic material to make contact with the germanium layer.