Search

EP-4736240-A1 - TECHNOLOGIES FOR A HYBRID OPTICAL CHIP-TO-CHIP COUPLING

EP4736240A1EP 4736240 A1EP4736240 A1EP 4736240A1EP-4736240-A1

Abstract

Technologies for hybrid optical chip-to-chip coupling are disclosed. In an illustrative embodiment, light from a waveguide in a photonic integrated circuit (PIC) die is collimated using a micromirror and directed towards a glass substrate. Another micromirror in the glass substrate focuses the light into a waveguide defined in a bulk layer of the glass substrate. In the illustrative embodiment, the waveguide is directly written into the bulk layer using an ultrafast laser. The glass substrate also has waveguides with a large difference in the index of refraction in a layer above the bulk substrate, such as silicon nitride waveguides in silicon oxide cladding. The directly-written waveguides can be evanescently coupled to the silicon nitride waveguides. The silicon nitride waveguides can then be used for two-dimensional routing throughout the glass substrate. The light can be coupled back into a directly-written waveguide before it is transmitted to another PIC die.

Inventors

  • PSAILA, NICHOLAS D.

Assignees

  • Intel Corporation

Dates

Publication Date
20260506
Application Date
20231115

Claims (20)

  1. 1. An apparatus comprising: a photonic integrated circuit (PIC) die comprising a first set of one or more waveguides; and a glass substrate comprising: a second set of one or more waveguides, wherein individual waveguides of the second set of one or more waveguides are direct-write waveguides; and a third set of one or more waveguides, wherein individual waveguides of the third set of one or more waveguides have a cladding, wherein the cladding of individual waveguides of the third set of one or more waveguides are a different material from the corresponding waveguide, wherein individual waveguides of the second set of one or more waveguides are coupled to individual waveguides of the first set of one or more waveguides and coupled to individual waveguides of the third set of one or more waveguides.
  2. 2. The apparatus of claim 1, further comprising a second PIC die, the second PIC die comprising a fourth set of one or more waveguides, wherein the glass substrate comprises a fifth set of one or more waveguides, wherein individual waveguides of the fifth set of one or more waveguides are coupled to individual waveguides of the fourth set of one or more waveguides and coupled to individual waveguides of the third set of one or more waveguides, wherein the second, third, and fifth sets of one or more waveguides in the glass substrate couple the first set of one or more waveguides to the fourth set of one or more waveguides.
  3. 3. The apparatus of claim 1 , further comprising a first set of one or more micromirrors and a second set of micromirrors, wherein individual micromirrors of the first set of one or more micromirrors are to collimate light from one of the first set of one or more waveguides and direct the collimated light towards one of the second set of micromirrors, wherein individual micromirrors of the second set of one or more micromirrors are to focus light from one of the first set of one or more micromirrors into one of the second set of one or more waveguides.
  4. 4. The apparatus of claim 1, wherein individual waveguides of the third set of one or more waveguides comprise silicon and nitrogen.
  5. 5. The apparatus of claim 4, wherein individual waveguides of the second set of one or more waveguides comprise silicon and oxygen.
  6. 6. The apparatus of any of claims 1-4, wherein, at a coupling interface, the first set of one or more waveguides and the second set of one or more waveguides are arranged in a two- dimensional multirow interconnect interface.
  7. 7. The apparatus of any of claims 1 -4, wherein the third set of one or more waveguides are arranged in two or more layers in the glass substrate.
  8. 8. The apparatus of any of claims 1-4, further comprising one or more optical components adjacent the glass substrate coupled to the third set of one or more waveguides.
  9. 9. The apparatus of claim 8, wherein the one or more optical components comprise one or more active optical components.
  10. 10. The apparatus of claim 8, wherein the one or more optical components comprise one or more passive optical components.
  11. 11. The apparatus of claim 10, wherein the one or more passive optical components comprise a cyclical arrayed waveguide grating.
  12. 12. An integrated circuit package comprising the apparatus of any of claims 1-4 and an electrical integrated circuit (EIC) die, wherein the EIC die is mated to the PIC die.
  13. 13. The integrated circuit package of claim 12, wherein the glass substrate is a glass interposer for the integrated circuit package, wherein the glass substrate comprises a plurality of through-glass vias.
  14. 14. An apparatus comprising: a photonic integrated circuit (PIC) die comprising a first set of one or more waveguides; a glass substrate comprising: a second set of one or more waveguides, wherein individual waveguides of the second set of one or more waveguides have a difference between a core index of refraction and a cladding index of refraction that is less than 0.01; and a third set of one or more waveguides, wherein individual waveguides of the second set of one or more waveguides have a difference between a core index of refraction and a cladding index of refraction that is more than 0.1, wherein individual waveguides of the second set of one or more waveguides are coupled to individual waveguides of the first set of one or more waveguides and coupled to individual waveguides of the third set of one or more waveguides.
  15. 15. The apparatus of claim 14, further comprising a second PIC die, the second PIC die comprising a fourth set of one or more waveguides, wherein the glass substrate comprises a fifth set of one or more waveguides, wherein individual waveguides of the fifth set of one or more waveguides are coupled to individual waveguides of the fourth set of one or more waveguides and coupled to individual waveguides of the third set of one or more waveguides, wherein the second, third, and fifth sets of one or more waveguides in the glass substrate couple the first set of one or more waveguides to the fourth set of one or more waveguides.
  16. 16. The apparatus of claim 14, further comprising a first set of one or more micromirrors and a second set of micromirrors, wherein individual micromirrors of the first set of one or more micromirrors are to collimate light from one of the first set of one or more waveguides and direct the collimated light towards one of the second set of micromirrors, wherein individual micromirrors of the second set of one or more micromirrors are to focus light from one of the first set of one or more micromirrors into one of the second set of one or more waveguides.
  17. 17. The apparatus of claim 14, wherein individual waveguides of the third set of one or more waveguides comprise silicon and nitrogen.
  18. 18. The apparatus of claim 17, wherein individual waveguides of the second set of one or more waveguides comprise silicon and oxygen.
  19. 19. The apparatus of any of claims 14-18, wherein, at a coupling interface, the first set of one or more waveguides and the second set of one or more waveguides are arranged in a two- dimensional multirow interconnect interface.
  20. 20. The apparatus of any of claims 14-18, wherein an optical connector for an optical fiber is defined at an edge of the glass substrate.

Description

TECHNOLOGIES FOR A HYBRID OPTICAL CHIP-TO-CHIP COUPLING CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Patent Application Serial No. 18/342,422 filed on June 27, 2023, and entitled “TECHNOLOGIES FOR A HYBRID OPTICAL CHIP-TO- CHIP COUPLING”, which is hereby incorporated by reference in its entirety. BACKGROUND [0002] Photonic integrated circuits (PICs) dies can be used for several applications, such as communications. PIC dies can offer high-speed, compact communication. However, PIC dies have drawbacks in certain situations, such as communicating across a large package. In a multi-die package, a silicon photonic waveguide routed across tens of millimeters may incur substantial signal loss and may be prohibitively expensive. Other optical communication options at the package level have drawbacks as well. Optical fibers can route between dies with low loss, but incorporating optical fibers at the package level suffers from integration and handling challenges. Polymer waveguides suffer from high loss, reliability issues, and integration issues such as poor resilience to high temperatures. Some approaches, such as glass-based ion-exchange waveguides and direct-write waveguides, can offer low-loss propagation but suffer from density restrictions due to limited refractive index contrast. Forming waveguides such as silicon nitride waveguides on a glass substrate can offer low-loss propagation and high density, but low-loss coupling to such waveguides from a PIC die can be difficult. BRIEF DESCRIPTION OF THE DRAWINGS [0003] FIG. 1 is an isometric view of a system including an integrated circuit package with a glass substrate, a photonic integrated circuit (PIC) die, and an electrical integrated circuit (EIC) die. [0004] FIG. 2 is a top-down view of the system of FIG. 1. [0005] FIG. 3 is a cross-sectional view of one embodiment of the system of FIG. 1. [0006] FIG. 4 is a cross-sectional view of one embodiment of the system of FIG. 1. [0007] FIG. 5 is a cross-sectional view of one embodiment of the system of FIG. 1. [0008] FIG. 6 is a cross-sectional view of one embodiment of the system of FIG. 1 . [0009] FIG. 7 is a cross-sectional view of one embodiment of the system of FIG. 1. [0010] FIG. 8 is a cross-sectional view of one embodiment of the system of FIG. 1. [0011] FIG. 9 is a cross-sectional view of one embodiment of the system of FIG. 1. [0012] FIG. 10 is a top-down view of one embodiment of the system of FIG. 1. [0013] FIGS. 11 and 12 are a simplified flow diagram of at least one embodiment of a method for manufacturing a system including a glass substrate with a PIC die and an EIC die mounted on it. [0014] FIG. 13 is a top view of a wafer and dies that may be included in a microelectronic assembly, in accordance with any of the embodiments disclosed herein. [0015] FIG. 14 is a cross-sectional side view of an integrated circuit device that may be included in a microelectronic assembly, in accordance with any of the embodiments disclosed herein. [0016] FIGS. 15A-15D are perspective views of example planar, gate-all-around, and stacked gate-all-around transistors. [0017] FIG. 16 is a cross-sectional side view of an integrated circuit device assembly that may include a microelectronic assembly, in accordance with any of the embodiments disclosed herein. [0018] FIG. 17 is a block diagram of an example electrical device that may include a microelectronic assembly, in accordance with any of the embodiments disclosed herein. DETAILED DESCRIPTION [0019] In various embodiments disclosed herein, a glass substrate can be created with one or more low-index-difference direct-write waveguides and one or more high-index-difference waveguides, such as silicon nitride waveguides, formed on the surface of the glass substrate. The direct-write waveguides offer relatively low sensitivity to misalignment and flexible 3D routing. The silicon nitride waveguides offer low-loss, dense routing of waveguides on the substrate. The direct-write waveguides can be used for coupling on and off of the glass substrate, and the silicon nitride waveguide can be used to carry signals across the glass substrate. Such a glass substrate can be integrated into a package with other components, such as photonic integrated circuit (PIC) dies and electrical integrated circuit (EIC) dies. Waveguides in the glass substrate can be coupled to waveguides in the PIC dies in various ways, as discussed in more detail below. [0020] As used herein, the phrase “communicatively coupled” refers to the ability of a component to send a signal to or receive a signal from another component. The signal can be any type of signal, such as an input signal, an output signal, or a power signal. A component can send or receive a signal to another component to which it is communicatively coupled via a wired or wireless communication medium (e.g., conductive traces, conductive contacts, air). Examples of components that are communicativ