Wafer level testing of optical components

Patent metadata

Field	Value
Publication number	US-11295994-B2
Application number	US-201916517404-A
Country	US
Kind code	B2
Filing date	Jul 19, 2019
Priority date	Jul 20, 2018
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

A system may include a wafer that includes ICs and defines cavities. Each cavity may be formed in a BEOL layer of the wafer and proximate a different IC. The system may also include an interposer that includes a transparent layer configured to permit optical signals to pass through. The interposer may also include at least one waveguide located proximate the transparent layer. The at least one waveguide may be configured to adiabatically couple at least one optical signal out of the multiple ICs. Further, the interposer may include a redirecting element optically coupled to the at least one the waveguide. The redirecting element may be located proximate the transparent layer and may be configured to receive the at least one optical signal from the at least one waveguide. The redirecting element may also be configured to vertically redirect the at least one optical signal towards the transparent layer.

First claim

What is claimed is:

1. A method comprising:
forming a wafer, the wafer comprising a plurality of integrated circuits (ICs) and each IC of the plurality of ICs comprising one or more adiabatic coupler;
forming a plurality of cavities in a back end of line (BEOL) layer of the wafer, each cavity of the plurality of cavities being formed proximate a different IC of the plurality of ICs;
positioning an interposer within a cavity of the plurality of cavities proximate a corresponding IC of the plurality of ICs; and
adiabatically coupling an optical signal out of the corresponding IC of the plurality of ICs into a waveguide of the interposer.

2. The method of claim 1 , wherein the cavity of the plurality of cavities is a first cavity of the plurality of cavities, the corresponding IC of the plurality of ICs is a first IC of the plurality of ICs, and the optical signal is a first optical signal, the method further comprising:
positioning the interposer within a second cavity of the plurality of cavities; and
adiabatically coupling a second optical signal out of a second IC of the plurality of ICs into the waveguide of the interposer.

3. The method of claim 1 , the method further comprising:
measuring the optical signal adiabatically coupled into the waveguide; and
determining whether the corresponding IC is operating properly based on the measurement of the optical signal.

4. The method of claim 1 , the method further comprising:
converting the optical signal to an electrical signal;
measuring the electrical signal; and
determining whether the corresponding IC is operating properly based on the measurement of the electrical signal.

5. The method of claim 1 , the method further comprising:
providing the optical signal to an external device via an optical component; and
measuring, by the external device, the optical signal.

6. The method of claim 1 , wherein each IC of the plurality of ICs comprises one or more adiabatic couplers and the plurality of cavities are formed in the wafer such that a portion of a front end of line (FEOL) layer of the wafer is located above the one or more adiabatic couplers in each IC of the plurality of ICs and the portion of the FEOL layer is thin enough to enable optical coupling between the one or more adiabatic couplers in each IC of the plurality of ICs and one or more waveguide in the interposer.

7. A method of testing a plurality of integrated circuits (ICs) in a wafer, each IC having one or more adiabatic couplers, the method comprising:
forming a cavity in a back end of line (BEOL) layer of the wafer proximate the one or more adiabatic couplers of each of the ICs;
positioning one or more waveguides of an interposer for a testing fixture in a corresponding one of the cavities proximate the one or more adiabatic couplers of a corresponding one of the ICs;
adiabatically coupling one or more optical signals between the one or more adiabatic couplers of the corresponding IC and one or more waveguides of the interposer; and
measuring at least one of the one or more optical signals having been adiabatically coupled.

8. The method of claim 7 , wherein adiabatically coupling the one or more optical signals between the one or more adiabatic couplers and the one or more waveguides comprises adiabatically coupling a receive one of the one or more optical signals out of a first the one or more adiabatic couplers into a first of the one or more waveguides of the interposer.

9. The method of claim 8 , wherein measuring the at least one optical signal comprises determining optical loss or degradation occurring within the first adiabatic coupler and/or within an optical element of the corresponding IC by measuring a signal strength of the receive optical signal adiabatically coupled out of the first adiabatic coupler into the first waveguide.

10. The method of claim 7 , wherein adiabatically coupling the one or more optical signals between the one or more adiabatic couplers and the one or more waveguides comprises adiabatically coupling a transmit one of the one or more optical signals from a second of the one or more waveguides of the interposer into a second of the one or more adiabatic coupler so as to adiabatically couple, as a result of the transmit optical signal, the receive optical signal out of the first adiabatic coupler into the first waveguide of the interposer.

11. The method of claim 7 , wherein measuring the at least one optical signal comprises redirecting the at least one optical signal in the interposer from at least one of the one or more waveguides to at least one optical component of the testing fixture by using at least one redirecting element disposed in the interposer and optically coupled to the at least one waveguide.

12. The method of claim 11 , wherein redirecting by using the at least one redirecting element comprises:
redirecting the at least one coupled optical signal with a grating coupler configured to redirect the at least one coupled optical signal from the at least one waveguide; and
reducing degradation of the at least one redirected optical signal using a mirror located below the grating coupler in the interposer.

13. The method of claim 11 , wherein redirecting by using the at least one redirecting element comprises redirecting the at least one optical signal using a mirror configured to vertically redirect the at least one optical signal in the interposer from the at least one waveguide.

14. The method of claim 7 , further comprising assisting optical coupling of the one or more adiabatic couplers and the one or more waveguides by using a removable material in a space between the interposer and a surface of the corresponding cavity.

15. The method of claim 7 , further comprising:
positioning the interposer within another one of the cavities having another corresponding one of the ICs;
adiabatically coupling one or more optical signals between the one or more adiabatic couplers of the other corresponding IC and the one or more waveguides of the interposer; and
measuring at least one of the one or more optical signals having been adiabatically coupled.

16. The method of claim 7 , wherein measuring the at least one optical signal comprises determining whether the corresponding IC is operating properly based on the measurement.

17. The method of claim 7 , wherein measuring the at least one optical signal comprises:
converting the at least one optical signal into at least one electrical signal;
measuring the at least one electrical signal; and
determining whether the corresponding IC is operating properly based on the measurement.

18. The method of claim 7 , wherein measuring the at least one optical signal comprises:
providing the at least one optical signal to an external device via an optical component; and
measuring, by the external device, the at least one optical signal.

19. The method of claim 7 , wherein forming the cavity in the back end of line (BEOL) layer of the wafer proximate each of the ICs comprises forming each cavity with a portion of a front end of line (FEOL) layer of the wafer located above the one or more adiabatic couplers in each IC, the portion of the FEOL layer being thin enough to enable optical coupling between the one or more adiabatic couplers in each IC and the one or more waveguides in the interposer.

Assignees

• Finisar Corp
• Ii Vi Delaware Inc

Inventors

• Lin Shiyun
• Mahgerefteh Daniel
• Park Bryan
• Lee Jin-Hyoung

Classifications

• H10P74/27

  Structural arrangements therefor · CPC title

• H10P74/207 Primary

  Electrical properties, e.g. testing or measuring of resistance, deep levels or capacitance-voltage characteristics · CPC title

• H10P74/277

  Circuits for electrically characterising or monitoring manufacturing processes, e.g. circuits in tested chips or circuits in testing wafers · CPC title

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• G01N21/9501 Primary

  Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20) · CPC title