Stacked Image Sensor Pad Exposure With Partial Backside Etching
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Solution Overview
Problem
Existing image sensing devices face challenges in efficiently exposing conductive pads during manufacturing, leading to etch damage and non-uniform thickness, which affects electrical performance and resistance.
Innovation Solution
A method of manufacturing a stack type image sensing device involves forming a conductive pad within the substrate before bonding, allowing partial etching to expose the pad, reducing etch damage and improving thickness uniformity, and enabling direct contact with bonding pads for reduced resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conductive pad is exposed by etching the substrate after bonding, then the electrical connection is achieved, but etch damage and non-uniform thickness occur
Solution Approach 1:
The conductive pad is formed to extend into the substrate before the bonding process. This preliminary positioning allows the pad to be pre-formed at the correct location and depth, avoiding the need for post-bonding etching that causes damage and thickness variation. The pad extension structure is created in advance during substrate processing, ensuring uniform thickness is maintained throughout the bonding operation.
2Reliability
If the conductive pad is exposed by etching the substrate after bonding, then the electrical connection is achieved, but etch damage occurs
Solution Approach 1:
The conductive pad is pre-formed extending into the substrate before bonding occurs. This preliminary action eliminates the need for subsequent etching operations that would expose the pad, thereby preventing etch damage entirely while still achieving the required electrical connection through the pre-positioned pad structure.
3Reliability
If the conductive pad extends directly to the bonding interface, then wiring resistance is reduced, but manufacturing complexity increases
Solution Approach 1:
The conductive pad is segmented into distinct portions: a first portion extending into the substrate and a second portion exposed at the bonding interface. This segmentation allows each portion to serve its specific function - the first portion provides low-resistance electrical connection within the substrate while the second portion enables bonding contact, achieving low resistance without excessive structural complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes etch damage and enhances pad thickness uniformity, thereby reducing wiring resistance and improving electrical characteristics of the image sensing device.
Implementation Method 1
bonding the first bonding layer and the second bonding layer to each other to expose a back side of the first substrate
Implementation Method 2
etching the exposed back side of the first substrate by a partial thickness of a thickness of the first substrate to expose the first conductive pad in the first substrate
Data Source
AI summary
Image sensing devices and methods of manufacturing image sensing devices are disclosed. In an embodiment, a method of manufacturing an image sensing device May include stacking a first structure that includes a first substrate, a first device layer, a first conductive pad, a first bonding layer, and a second structure that includes a second substrate, a second device layer, a second bonding layer by bonding the first bonding layer and the second bonding layer to each other to expose a back side of the first substrate, and etching the exposed back side of the first substrate by a partial thickness of a thickness of the first substrate to expose the first conductive pad in the first substrate.