Protective Layer Formation for Damage-Free Wafer Silicon Removal

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional wafer processing methods result in surface damage during the removal of silicon substrate thickness, compromising the integrity of the second silicon substrate.

Innovation Solution

A protective layer is formed on the second silicon substrate after bonding with the first wafer, using silicon oxide or silicon nitride, to prevent surface damage during the silicon removal process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a conventional process is used to remove the thickness of a device wafer, then the component size is reduced, but the surface of another device wafer is damaged

Engineering Contradiction:

Improvewafer thicknessVSAvoidsurface damage

Core Design Contradiction:

Length of moving objectVSObject-affected harmful factors

Solution Approach 1:

A protective layer is introduced as an intermediary between the etchant and the second silicon substrate. This protective layer selectively protects the second silicon substrate from etching while allowing the first silicon substrate to be removed, thereby preventing surface damage to the second wafer during the thickness reduction process

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective layer is selectively formed only on the second silicon substrate, creating local differentiation in etching resistance. This allows the first silicon substrate to be etched away while the second silicon substrate remains protected, enabling localized material removal without damaging other components

Inventive Principle:

Principle #3Local quality

2Length of moving object

If the thickness of the wafer is reduced, then the device size is reduced, but the manufacturing complexity increases

Engineering Contradiction:

Improvewafer thicknessVSAvoidprocess complexity

Core Design Contradiction:

Length of moving objectVSDevice complexity

Solution Approach 1:

The protective layer is formed in advance on the second silicon substrate before the etching process begins. This preliminary protective action simplifies the overall process by pre-preparing the second wafer for selective removal, avoiding the need for complex real-time control during etching

Inventive Principle:

Principle #10Preliminary action

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 protective layer maintains the integrity of the second silicon substrate by shielding it from etchants, ensuring the surface remains undamaged and functional.

Implementation Method 1

A protective layer is formed on the second silicon substrate after bonding with the first wafer, using silicon oxide or silicon nitride, to prevent surface damage during the silicon removal process

Methodology Applied

Scientific EffectChemical resistance:

Data Source

PatentUS20250349599A1Method of forming protective layer utilized in silicon remove process

Publication Date: 2025.11.13 UNITED MICROELECTRONICS CORP

AI summary

A method of forming a protective layer utilized in a silicon remove process includes bonding a first wafer to a second wafer, wherein the first wafer comprises a first silicon substrate with a first device structure disposed thereon and the second wafer comprises a second silicon substrate with a second device structure disposed thereon. After that, a first trim process is performed to thin laterally an edge of the first wafer and an edge of the second device structure. After the first trim process, a protective layer is formed to cover a back side of the second silicon substrate. After forming the protective layer, a silicon remove process is performed to remove only the first silicon substrate.