Wafer Packaging Using Hydrolytic Bonding for Thin Glass Alignment
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Solution Overview
Problem
Thin glass sheets used for wafer protection lack mechanical strength and are prone to warpage, making the wafer packaging process challenging due to alignment issues and increased risk of cracking during the manufacturing process.
Innovation Solution
A wafer packaging method involving a hydrolytic temporary bonding layer between a light transmissive carrier and protection sheet, which is immersed in a high temperature liquid to eliminate adhesion force, allowing for precise alignment and increased strength without the need for additional tape, using a thicker carrier to support a thinner protection sheet for improved transmittance and image detecting ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a thinner glass sheet is used for wafer protection, then light transmittance and image detecting ability are improved, but mechanical strength decreases and warpage increases
Solution Approach 1:
The solution divides the protection structure into two separate components: a thick carrier glass (400-600 μm) for mechanical strength and a thin protection glass (50-150 μm) for light transmittance. The carrier glass is segmented from the protection glass through a hydrolytic bonding layer that can be selectively removed, allowing each component to fulfill its specific function without compromise.
Solution Approach 2:
A hydrolytic bonding layer serves as an intermediary between the carrier glass and protection glass. This intermediate layer enables temporary bonding during processing, allowing precise alignment and handling of the thin protection glass, while its hydrolytic property enables controlled removal after bonding, separating the two glass components.
2Illumination intensity
If a thinner glass sheet is used, then light transmittance is improved, but alignment precision deteriorates due to warpage
Solution Approach 1:
The protection system is segmented into a rigid carrier glass and a thin protection glass bonded via a hydrolytic layer. The carrier glass provides a stable, warp-free substrate for precise alignment, while the thin protection glass maintains optical performance. The hydrolytic bonding layer enables precise alignment during the bonding process before being removed.
Solution Approach 2:
The hydrolytic bonding layer acts as an intermediary that facilitates precise alignment between the carrier and protection glass. Its temporary bonding capability allows for accurate positioning and alignment during processing, and its subsequent removable nature enables separation after alignment is achieved.
3Strength
If additional tape is added to increase strength, then mechanical strength is improved, but device complexity increases
Solution Approach 1:
The carrier glass and protection glass are merged into a single bonded structure through the hydrolytic bonding layer, eliminating the need for separate tape layers. This unified structure provides mechanical strength through the thick carrier glass while maintaining simplicity by avoiding additional tape materials and associated processing steps.
Solution Approach 2:
The hydrolytic bonding layer serves as an intermediary bonding mechanism that replaces the need for additional tape. Its temporary bonding capability provides the necessary mechanical strength during processing, and its removable nature simplifies the overall structure by eliminating permanent tape attachments.
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 method prevents warpage of the protection sheet, ensures accurate alignment, and enhances the mechanical strength of both the sheet and wafer, allowing for flexible grinding and improved image detecting ability without the need for additional tape, while enabling easy separation of the carrier from the protection sheet post-processing.
Implementation Method 1
A hydrolytic temporary bonding layer is formed on the light transmissive carrier
Implementation Method 2
The light transmissive carrier, the hydrolytic temporary bonding layer, the light transmissive protection sheet, and the wafer are immersed in a high temperature liquid, such that the adhesion force of the hydrolytic temporary bonding layer is eliminated
Data Source
AI summary
A wafer packaging method includes the following steps. A light transmissive carrier is provided. A hydrolytic temporary bonding layer is formed on the light transmissive carrier. A first surface of a light transmissive protection sheet is bonded to the hydrolytic temporary bonding layer, such that the hydrolytic temporary bonding layer is located between the light transmissive protection sheet and the light transmissive carrier. A second surface of the light transmissive protection sheet facing away from the first surface is bonded to a third surface of a wafer. The light transmissive carrier, the hydrolytic temporary bonding layer, the light transmissive protection sheet, and the wafer are immersed in a high temperature liquid, such that adhesion force of the hydrolytic temporary bonding layer is eliminated. The light transmissive protection sheet and the wafer are obtained from the high temperature liquid.