PIC Chip Inductor Placement for Bandwidth Stability
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Solution Overview
Problem
In silicon photonics packaging, varying wire lengths and loop heights due to reduced physical sizes and process variations lead to unstable bandwidth and poorer device performance, limiting the potential for increased overall bandwidth.
Innovation Solution
The use of an inductor positioned over a photonic integrated circuit (PIC) chip with its terminal ends connected to the PIC and transimpedance amplifier (TIA) chip, along with a multilayer dielectric body containing inductors and ground vias, minimizes dimensional variability and stabilizes inductance, preventing unwanted feedback loops and enabling smaller, higher-density packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding is used to interconnect PIC chip and TIA chip, then electrical connection is achieved, but dimensional variability of wire length and loop height leads to unstable bandwidth and poor device performance
Solution Approach 1:
The patent introduces an inductor as an intermediary component between the PIC chip and TIA chip. This inductor is directly mounted on the PIC chip substrate, serving as a stable reference point for connection. By using this intermediary structure, the system achieves controlled inductance values while eliminating the dimensional variability inherent in traditional wire bonding methods.
Solution Approach 2:
The patent replaces the mechanical wire bonding system with a direct electrical connection system using conductive traces and vias on the substrate. This substitution eliminates the mechanical variability of wire length and loop height, providing stable electrical connection and consistent bandwidth performance without relying on manual or automated wire bonding processes.
2Area of stationary object
If reduced physical sizes are used in semiconductor packaging, then packaging footprint is minimized, but wire length variability increases leading to unstable bandwidth
Solution Approach 1:
The patent transitions from three-dimensional wire bonding to a planar two-dimensional trace system on the substrate. By routing electrical connections through conductive traces and vias within the substrate plane, the system achieves compact packaging while maintaining controlled and consistent electrical path lengths, thereby preserving bandwidth stability despite reduced physical dimensions.
Solution Approach 2:
The patent merges the inductor component directly with the PIC chip substrate, eliminating the need for separate wire bonding connections. This integration combines multiple functions (inductance, connection, and signal routing) into a unified structure, achieving compact packaging while ensuring stable electrical connection and consistent bandwidth performance.
3Ease of manufacture
If process variations occur in packaging, then manufacturing flexibility is maintained, but interconnecting wire dimensions vary leading to higher parasitic inductance
Solution Approach 1:
The patent replaces the mechanical wire bonding system with a planar trace system fabricated through standard PCB processes. This substitution eliminates the sensitivity to process variations that affects wire dimensions, as the conductive traces and vias are precisely controlled during substrate fabrication, thereby minimizing parasitic inductance while maintaining manufacturing flexibility.
4Manufacturing precision
If variable wire lengths are used due to process variations, then manufacturing tolerance is relaxed, but bandwidth value becomes unstable and device performance deteriorates
Solution Approach 1:
The patent introduces an inductor mounted on the substrate as an intermediary reference structure. This intermediary provides a fixed, controlled inductance value that is independent of trace length variations. By connecting the TIA chip to this stable reference point through controlled-impedance traces, the system achieves bandwidth stability even when manufacturing tolerances result in slight trace length variations.
Data Source
AI summary
The present disclosure relates to packaging of integrated circuit chips for semiconductor devices. More particularly, the present disclosure relates to packaging of multiple chips for silicon photonics devices. The present disclosure provides a semiconductor device including a photonic integrated circuit (PIC) chip, an inductor positioned over the PIC chip, and a transimpedance amplifier (TIA) chip positioned over the PIC chip. The inductor has a first terminal end and a second terminal end, and the first terminal end is connected to the PIC chip.