Bond Pad Via Structure for Misalignment-Tolerant Die Bonding

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Solution Overview

Problem

Existing wafer-to-wafer bonding technologies face challenges in achieving efficient bonding with minimal misalignment effects, particularly in reducing contact resistance and maintaining electrical performance.

Innovation Solution

The method involves forming bond pad vias (BPVs) and bond pads in separate processing steps, allowing for closer spacing and smaller area metal pads, which reduces the size of the die or package and minimizes misalignment effects on contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal pads are formed with larger area and wider spacing to ensure reliable bonding, then bonding reliability is improved, but die or package size increases

Engineering Contradiction:

Improvebonding reliabilityVSAvoiddie or package size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The bonding structure is segmented into multiple components: metal pads, bond pad vias (BPVs), and bond pads formed in separate processing steps. This segmentation allows each component to be optimized independently, enabling smaller metal pad areas while maintaining reliable electrical connection through the via structure that bridges the pads across wafer interfaces

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Bond pad vias (BPVs) serve as intermediary elements between the metal pads on one wafer and the bond pads on the bonded wafer. These vias act as mediators that ensure continuous electrical connection even when metal pads are reduced in size, allowing smaller pad areas without compromising bonding reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If metal pads are spaced closer together to reduce die size, then routing density is improved, but manufacturing precision requirements increase due to misalignment risks

Engineering Contradiction:

Improverouting densityVSAvoidalignment precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The bonding interconnection is segmented into multiple stages: metal pads, bond pad vias, and bond pads. This multi-stage segmentation provides alignment tolerance at each interface, allowing closer spacing of metal pads for improved routing density while the via structures serve as alignment references that accommodate misalignment without compromising electrical connection

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bond pad via structure provides beforehand cushioning against misalignment by creating overlapping connection zones. The vias extend through the wafer thickness and provide a buffer zone that accommodates positional variations, cushioning the system against alignment errors before they can affect the final bonding quality

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS12205911B2Bonding structure and method of forming same

Publication Date: 2025.01.21 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A package includes a first die that includes a first metallization layer, one or more first bond pad vias on the first metallization layer, wherein a first barrier layer extends across the first metallization layer between each first bond pad via and the first metallization layer, and one or more first bond pads on the one or more first bond pad vias, wherein a second barrier layer extends across each first bond pad via between a first bond pad and the first bond pad via, and a second die including one or more second bond pads, wherein a second bond pad is bonded to a first bond pad of the first die.