Integrated photo detector, method of making the same

1. An integrated photo detector with enhanced electrostatic discharge damage (ESD) protection comprising:

an input waveguide formed in a Si-on-insulator (SOI) substrate for receiving a light wave;

a first photodiode formed in the SOI substrate and coupled to the input waveguide, the first photodiode being associated with a first p-electrode and a first n-electrode;

a second photodiode formed in the SOI substrate associated with a second p-electrode and a second n-electrode forming a capacitance no larger than a few femto Faradays;

a first electrode and a second electrode disposed respectively on the SOI substrate, the first electrode being respectively connected to the first p-electrode and the second p-electrode, the second electrode being respectively connected to the first n-electrode and the second n-electrode.

2. The integrated photo detector of claim 1 , wherein the first photodiode is a Germanium-based photodiode configured to detect the light wave modulated with a high data rate.

3. The integrated photo detector of claim 1 , wherein the input waveguide comprise a material of silicon or germanium or silicon nitride formed in the SOI substrate for transmitting the light wave therein.

4. The integrated photo detector of claim 2 , wherein the Germanium-based photodiode comprises a p-type Silicon base patterned within the SOI substrate and an intrinsic Germanium block formed overlying the p-type Silicon base, the p-type Silicon base being partially implanted via a first mask to form a first p++ doped region and the intrinsic Germanium block being partially implanted via a second mask to form a first n++ doped region.

5. The integrated photo detector of claim 4 , wherein the first p-electrode is physically bounded onto the p++ doped region and the first n-electrode is physically bounded onto the n++ doped region.

6. The integrated photo detector of claim 1 , wherein the second photodiode is a Silicon-based photodiode coupled to the Germanium-based photodiode to provide an electrostatic discharge damage threshold of ±100V or higher.

7. The integrated photo detector of claim 6 , wherein the Silicon-based photodiode comprises a p-type Silicon region joined with an n-type Silicon region patterned within the SOI substrate, the p-type Silicon region being partially implanted via a third mask to form a second p++ doped region and the n-type Silicon region being partially implanted via a fourth mask to form a second n++ doped region.

8. The integrated photo detector of claim 1 , wherein each of the second p-electrode and the second n-electrode is made substantially smaller in size than each of the first p-electrode and the first n-electrode.

9. The integrated photo detector of claim 2 , wherein each of the first electrode and the second electrode is made substantially larger in size up to a few tens to hundreds of micrometers sufficient for forming a soldering connection with an external digital circuit for outputting an electric signal converted by the Germanium-based photodiode.

10. The integrated photo detector of claim 9 wherein the electric signal substantially maintains the high data rate of the light wave.

11. The integrated photo detector of claim 1 , wherein each of the first p-electrode, the second p-electrode, the first n-electrode, the second n-electrode, the first electrode, and the second electrode is formed by patterning a single metallic layer including a first shaped section connected between the first p-electrode and the first electrode, a second shaped section connected between the first n-electrode and the second electrode, a first trace line connected between the second p-electrode and the first electrode, and a second trace line connected between the second n-electrode and the second electrode.

12. The integrated photo detector of claim 1 , wherein the first/second trace line comprises a width of a few micrometers or less for minimizing the capacitance and yet maintaining electrical connection; the first/second shaped section comprises a reducing width from about hundreds of micrometers of the first/second electrode to a few micrometers of the first p/n-electrode.

13. An integrated photo detector with enhanced electrostatic discharge damage (ESD) protection comprising:

a Germanium photodiode comprising an intrinsic Germanium layer formed on a p-type Silicon base layer patterned within a Si-on-Insulator (SOI) substrate, the intrinsic Germanium layer comprising a first n++ doped region and the p-type Silicon base layer comprising a first p++ doped region;

a Silicon photodiode comprising a Silicon region patterned within the SOI substrate to form a p-type Silicon portion joined with a n-type Silicon portion, the p-type Silicon portion comprising a second p++ doped region and the n-type Silicon portion comprising a second n++ doped region;

a first metallic layer being pattered to include a first p-electrode coupled to the first p++ doped region, a second p-electrode coupled to the second p++ doped region, a first electrode connected to the first p-electrode and the second p-electrode;

a second metallic layer being pattered to include a first n-electrode coupled to the first n++ doped region, a second n-electrode coupled to the second n++ doped region, a second electrode connected to the first n-electrode and the second n-electrode;

wherein the Silicon photodiode is coupled with the Germanium photodiode electrically in parallel with a capacitance of no greater than a few femto Faradays and an enhanced ESD threshold of about ±100V.

14. The integrated photo detector of claim 13 further comprising a first shaped metallic layer with a reducing width connected from the first electrode to the first p-electrode, a second shaped metallic layer with a reducing width connected from the second electrode to the first n-electrode, a first thin trace line of a few micrometers connected between the first electrode and the second p-electrode, and a second thin trace line of a few micrometers connected between the second electrode and the second n-electrode.

15. A method for manufacturing an integrated photo detector with improved electrostatic discharge damage (ESD) protection, the method comprising:

forming a first Silicon base block and a second Silicon base block on a substrate;

forming a Germanium photodiode partially in the first Silicon base block, the Germanium photodiode being associated with a first p-electrode and a first n-electrode;

forming a Silicon photodiode in the second Silicon bask block, the Silicon photodiode being associated with a second p-electrode and a second n-electrode, the second p-electrode and the second n-electrode serving as two terminals of a capacitance no larger than a few femto Faradays;

forming a first electrode and a second electrode separately on the substrate;

forming a first metallic layer on the substrate to connect the first electrode respectively to the first p-electrode and the second p-electrode, the first metallic layer being patterned to have a first portion with a reducing width connecting the first electrode to the first p-electrode and a second portion with a first trace line connecting the first electrode to the second p-electrode;

forming a second metallic layer on the substrate to connect the second electrode respectively to the first n-electrode and the second n-electrode, the second metallic layer being patterned to have a third portion with a reducing width to connect the second electrode to the first n-electrode and a fourth portion with a second trace line to connect the second electrode to the second n-electrode.

16. The method of claim 15 wherein the first Silicon base block is a p-type Silicon layer and the second Silicon base block comprises a p-type Silicon portion joined with a n-type Silicon portion.

17. The method of claim 16 wherein forming the Germanium photodiode comprises depositing an intrinsic Germanium layer on the p-type Silicon layer of the first Silicon base block; implanting a first n++ doped region in the intrinsic Germanium layer by masked implantation; implanting a first p++ doped region in the p-type Silicon layer; coupling the first n++ doped region to the first n-electrode; and coupling the first p++ region to the first p-electrode.

18. The method of claim 16 wherein forming the Silicon photodiode comprises implanting a second p++ doped region in the p-type Silicon portion of the second Silicon base block; implanting a second n++ doped region in the n-type Silicon portion of the second Silicon base block; coupling the second p++ doped region to the second p-electrode; and coupling the second n++ doped region to the second n-electrode.

19. The method of claim 15 wherein forming a first metallic layer comprises patterning a first portion with a shape of reducing width from a few tens to hundreds micrometers at the first electrode to a few micrometers at the first p-electrode and a second portion of a thin trace line with a width of a few micrometers connected between the first electrode and the second p-electrode; forming a second metallic layer comprises patterning a third portion with a shape of reducing width from a few tens to hundreds micrometers at the second electrode to a few micrometers at the first n-electrode and a fourth portion of a thin trace line with a width of a few micrometers connected between the second electrode and the second n-electrode.

20. The method of claim 19 wherein the first/second metallic layer is configured to couple the Silicon photodiode to the Germanium photodiode electrically in parallel with a characterized ESD threshold of about ±100V.

21. The method of claim 15 wherein forming the first/second electrode comprises preparing for a formation of a solder bump for connecting with an external electronic circuit.