Semiconductor Contact Structure With Sacrificial Layer for Etch Control

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Solution Overview

Problem

Existing semiconductor chip packaging technologies face challenges in effectively mitigating the galvanic effect during etching processes, which can lead to over-etching and undercutting of conductive structures, limiting design flexibility and reliability.

Innovation Solution

The implementation of a sacrificial layer made of the same material as the seed layer over the multi-layer conductive contact helps protect the underlying metal layers from over-etching, minimizing the galvanic effect and ensuring precise control over the etching process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a multi-layer conductive contact structure is formed with seed layer extending beyond the contact, then design flexibility and electrical connectivity are improved, but the structure becomes susceptible to over-etching and undercutting during etching processes

Engineering Contradiction:

Improvedesign flexibilityVSAvoidstructural integrity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A sacrificial layer is introduced as an intermediary element between the etchant and the seed layer. This sacrificial layer has higher etch selectivity, meaning it etches faster than the seed layer. During the etching process, the sacrificial layer is completely removed while protecting the underlying seed layer and multi-layer conductive contact structure from over-etching and undercutting. This mediator approach allows the seed layer to extend beyond the contact periphery for design flexibility while maintaining structural integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If etching process is performed to remove sacrificial layer and seed layer, then manufacturing precision is improved by controlling contact width, but galvanic effect causes over-etching and undercutting

Engineering Contradiction:

Improvecontact width controlVSAvoidgalvanic effect

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The sacrificial layer serves as a protective intermediary that mitigates the galvanic effect during etching. By positioning the sacrificial layer over the multi-layer conductive contact and seed layer, it acts as a sacrificial anode that preferentially etches away, preventing the etchant from attacking the seed layer and underlying structures. This eliminates the harmful galvanic interaction between dissimilar metals during the etching process while maintaining precise contact width control.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention utilizes etch selectivity parameter differences between materials to resolve the contradiction. The sacrificial layer is specifically chosen to have higher etch rate compared to the seed layer and other metal layers. By controlling the etching parameters and utilizing material-specific etch rates, the process achieves precise contact width definition while preventing over-etching and undercutting caused by galvanic effects.

Inventive Principle:

Principle #35Parameter changes

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 reduces undercutting and maintains the structural integrity of the conductive contacts, enhancing the reliability and design flexibility of semiconductor chip packages by preventing over-etching and maintaining the desired contact width.

Implementation Method 1

mitigating the galvanic effect during etching processes

Methodology Applied

Scientific EffectGalvanic effect:

Implementation Method 2

performing a metal etch to reduce the seed layer in the first dimension based on the contact width of the multi-layer conductive contact and remove the sacrificial layer

Methodology Applied

Scientific EffectEtching:

Data Source

PatentUS20260053044A1Forming semiconductor chip package with a sacrifical layer

Publication Date: 2026.02.19 TEXAS INSTRUMENTS INC

AI summary

A method of forming an integrated circuit (IC) is provided. The method includes forming a seed layer of a first metal material over a circuit on a device side of a semiconductor die. The method also includes forming a multi-layer conductive contact on the seed layer. The multi-layer conductive contact has a width in a first dimension and includes a plurality of layers of different metal materials and a portion of the seed layer extends outwardly from a periphery of the multi-layer conductive contact. The method further includes forming a sacrificial layer of the first metal material over the multi-layer conductive contact. The method yet further includes etching to remove the seed layer and the sacrificial layer.