3D Semiconductor Wafer Buffer Layer for Carrier Switch Topography

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Solution Overview

Problem

The large topography variation on the upper surface of interposer structures in chip-on-wafer-on-substrate packages poses challenges during carrier-switch processes, leading to potential damage of sub-underbump metallurgies and adhesive issues due to the need for thick adhesives, which are difficult to remove without damaging the underlying structures.

Innovation Solution

A buffer layer is deposited over the conductive features and dielectric layers to smooth the topography, allowing for the use of thinner adhesives during carrier-switch processes, reducing the risk of damage to the underlying structures during adhesive removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If thick adhesive is used to attach carrier during carrier-switch process, then adhesive can cover large topography variation, but adhesive removal becomes difficult and may damage sub-underbump metallurgies

Engineering Contradiction:

Improvetopography variationVSAvoidadhesive removal

Core Design Contradiction:

ShapeVSEase of manufacture

Solution Approach 1:

The invention segments the adhesive system into two distinct layers: a buffer layer (first adhesive layer) that remains to protect the metallurgies, and a carrier attachment layer (second adhesive layer) that is removed with the carrier. This segmentation allows each layer to have optimized thickness and function, resolving the contradiction between covering topography and enabling easy removal.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The buffer layer acts as a pre-established protective cushion between the carrier attachment layer and the sub-underbump metallurgies. This beforehand cushioning ensures that when the carrier is removed, the metallurgies are already protected from damage, resolving the harm caused by thick adhesive removal.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Shape

If thick adhesive is used to attach carrier, then large topography variation is covered, but damage risk to sub-underbump metallurgies increases during adhesive removal

Engineering Contradiction:

Improvetopography variationVSAvoiddamage to sub-underbump metallurgies

Core Design Contradiction:

ShapeVSObject-affected harmful factors

Solution Approach 1:

By segmenting the adhesive system into a protective buffer layer and a removable carrier attachment layer, the invention eliminates the harm to metallurgies while still covering the topography variation. The buffer layer remains in place to protect the metallurgies during the entire process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The buffer layer provides beforehand cushioning protection to the sub-underbump metallurgies, ensuring they are shielded from damage during carrier attachment and removal processes, thus resolving the harmful effects.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If thin adhesive is used, then adhesive removal is easy, but large topography variation cannot be covered

Engineering Contradiction:

Improveadhesive removalVSAvoidtopography variation

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

The invention divides the adhesive function into two segments: the buffer layer handles the topography coverage requirement, while the thin carrier attachment layer handles the easy removal requirement. This segmentation allows both contradictory requirements to be satisfied simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The buffer layer acts as an intermediary between the substrate and the carrier attachment layer. It mediates the topography variation by providing a smooth surface for carrier attachment while protecting the underlying metallurgies, thus enabling thin adhesive use without compromising topography coverage.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Shape

If thick adhesive is used, then large topography variation is covered, but process complexity increases

Engineering Contradiction:

Improvetopography variationVSAvoidadhesive layer structure

Core Design Contradiction:

ShapeVSDevice complexity

Solution Approach 1:

While segmentation into two layers does increase structural complexity, it simplifies the overall process by enabling standard thin-adhesive processing techniques and eliminating the need for complex thick-adhesive removal procedures. The segmented structure is easier to control and process.

Inventive Principle:

Principle #1Segmentation

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

The buffer layer effectively reduces the topography, enabling the use of thinner adhesives that can be easily removed, thereby protecting the sub-underbump metallurgies and ensuring the integrity of the interposer structure.

Implementation Method 1

A buffer layer is deposited over the conductive features and dielectric layers to smooth the topography

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS12593704B2Three-dimensional semiconductor device and method

Publication Date: 2026.03.31 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Embodiments provide a method of performing a carrier switch for a device wafer, attaching a second wafer and removing a first wafer. A buffer layer is deposited over the device wafer, buffer layer reducing the topography of the surface of the device wafer. After the carrier switch a film-on-wire layer is removed from the buffer layer and then the buffer layer is at least in part removed.