Optical modulator and method of forming the same

Patent metadata

Field	Value
Publication number	US-12422699-B2
Application number	US-202217816764-A
Country	US
Kind code	B2
Filing date	Aug 2, 2022
Priority date	Aug 2, 2022
Publication date	Sep 23, 2025
Grant date	Sep 23, 2025

Abstract

A method includes receiving a silicon substrate; forming a first doped region and a second doped region in the silicon substrate; forming a third doped region and fourth doped region on upper portions of the first doped region and the second doped region, respectively; and patterning the silicon substrate to form an optical modulator. The optical modulator includes: a first section; a second section and a third section at least formed from the first and second doped regions, respectively; a fourth section, including a first height less than that of the first section and the second section and arranged between the first section and the second section, the fourth section being an undoped region; and a fifth section immediately adjacent to the fourth section, the fifth section including a height less than that of the first section and the second section and different from the first height.

First claim

What is claimed is:

1. A method, comprising:
receiving a silicon substrate;
forming a first doped region and a second doped region in the silicon substrate and laterally spaced by a distance;
forming a third doped region and a fourth doped region on upper portions of the first doped region and the second doped region, respectively, wherein the first doped region or and the second doped region has a first doping concentration between about 5E18 atoms/cm 3 and about 5E19 atoms/cm 3 ; and
patterning the silicon substrate to form an optical modulator, the optical modulator comprising:
a first section configured to allow an optical signal to propagate;
a second section and a third section at least formed from the first and second doped regions, respectively, and configured to receive a modulating signal;
a fourth section, including a first height less than that of the first section and the second section and arranged between the first section and the second section, the fourth section being an undoped region; and
a fifth section immediately adjacent to the fourth section, the fifth section including a height less than that of the first section and the second section and different from the first height, the fifth section arranged between the first section and the second section and formed from the first doped region.

2. The method of claim 1 , wherein the forming of the third doped region or the fourth doped region comprises using an ion implantation operation.

3. The method of claim 1 , wherein the third doped region or the fourth doped region has a second doping concentration greater than the first doping concentration.

4. The method of claim 3 , wherein the second doping concentration is between about 1E20 atoms/cm 3 and about 1E22 atoms/cm 3 .

5. The method of claim 1 , wherein the first section is undoped.

6. The method of claim 1 , wherein the first section is spaced apart from the second section by a first distance, and a width of the fourth section is in a range between about ½ and about ⅓ of the first distance.

7. The method of claim 1 , wherein the fourth section has an upper surface higher than the fifth section.

8. The method of claim 1 , wherein the first doped region and the second doped region are a P-type doped region and an N-type doped region, respectively.

9. The method of claim 1 , wherein the first doped region and the second doped region comprises a doping concentration that causes a phase change monotonically along with an increase or a decrease of the modulating signal.

10. The method of claim 1 , wherein a boundary of the first doped region or the second doped region is separated from a profile of an optical mode of the optical signal.

11. A method, comprising:
receiving a silicon substrate;
forming a first doped region and a second doped region in the silicon substrate and laterally spaced by a distance;
performing a first ion implantation operation to form a third doped region and a fourth doped region on upper portions of the first doped region and the second doped region, respectively, wherein the third or fourth doped region has a first doping concentration greater than a second doping concentration of the first or second doped region; and
patterning the silicon substrate to form an optical modulator, the optical modulator comprising:
a first section configured to allow an optical signal to propagate;
a second section and a third section at least formed from the first and second doped regions, respectively, and configured to receive a modulating signal;
a fourth section, including a first height less than that of the first section and the second section and arranged between the first section and the second section, the fourth section being an undoped region, wherein the fourth section is undoped; and
a fifth section immediately adjacent to the fourth section, the fifth section including a height less than that of the first section and the second section and different from the first height, the fifth section arranged between the first section and the second section and formed from the first doped region.

12. The method of claim 11 , wherein the third doped region and the fourth doped region are implanted on surfaces of the first doped region and the second doped region, respectively, prior to patterning the silicon substrate.

13. The method of claim 11 , wherein the forming of the first doped region and the second doped region comprises performing a second ion implantation operation on the silicon substrate.

14. The method of claim 11 , wherein the second doping concentration between about 5E17 atoms/cm 3 and about 1E20 atoms/cm 3 .

15. The method of claim 11 , wherein each of the second and third section has a cross-sectional area greater than the fourth section measured along a plane perpendicular to a direction in which the modulating signal flows.

16. The method of claim 11 , wherein the fifth section has an upper surface higher than the fourth section.

17. A method, comprising:
receiving a silicon substrate;
forming a first doped region and a second doped region in the silicon substrate and laterally spaced by a distance;
forming a third doped region and a fourth doped region on upper portions of the first doped region and the second doped region, respectively, wherein the third or fourth doped region has a first doping concentration greater than a second doping concentration of the first or second doped region; and
patterning the silicon substrate to form a first phase modulator, the first phase modulator comprising:
a first section configured to allow a first optical signal to propagate;
a second section and a third section at least formed from the first and second doped regions, respectively, and configured to receive a first modulating signal;
a fourth section, including a first height less than that of the first section and the second section and arranged between the first section and the second section, the fourth section including an undoped region; and
a fifth section immediately adjacent to the fourth section, the fifth section including a height less than that of the first section and the second section and different from the first height, the fifth section arranged between the first section and the second section and formed from the first doped region.

18. The method of claim 17 , further comprising patterning the silicon substrate to form a second phase modulator, the second phase modulator comprising:
an optical waveguide configured to allow a second optical signal to propagate; and
a diode configured to direct a second modulating signal to modulate the second optical signal, the diode including a first section and a second section on two sides of the optical waveguide, wherein the optical waveguide includes a stepped shape.

19. The method of claim 18 , wherein the first phase modulator and the second phase modulator constitute an optical modulator.

20. The method of claim 17 , wherein the fourth section and the fifth section have different heights.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Shih Chih-Tsung
• Yuan Feng
• Liu Wei-Kang
• Tsui Yingkit Felix

Classifications

• G02B2006/12142

  Modulator · CPC title

• G02B2006/12061

  Silicon · CPC title

• G02B2006/12123

  Diode · CPC title

• G02B6/12004

  Combinations of two or more optical elements · CPC title

• G02B6/134

  by substitution by dopant atoms · CPC title