Temperature-Dependent Adhesive for Wafer Handling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Temporary adhesives used in the semiconductor industry often fail to provide sufficient adhesive force to straighten warped wafers or hold them securely during processing due to deactivation at lower temperatures or mechanical forces, leading to instability and handling difficulties.
Innovation Solution
A method involving a permanent adhesive with a structured intermediate layer between the carrier and product substrate, and a temporary adhesive with a filler material having a lower coefficient of thermal expansion than the adhesive, which weakens at temperatures below 0°C to facilitate debonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a temporary adhesive is used to bond the carrier to the product substrate, then the carrier can be easily debonded after processing, but the adhesive force is insufficient to straighten warped wafers or hold them securely during processing
Solution Approach 1:
The adhesive composition changes its adhesive parameters based on temperature. At processing temperatures (above 0°C), the adhesive maintains high adhesive force to securely hold the wafer and straighten warped surfaces. At storage temperatures (below 0°C), the adhesive force automatically reduces, enabling easy mechanical debonding. This temperature-dependent parameter change resolves the contradiction between strong bonding during processing and easy separation afterward.
Solution Approach 2:
The adhesive undergoes a phase transition in its adhesive properties triggered by temperature change. The transition from a high-adhesion state (above 0°C) to a low-adhesion state (below 0°C) allows the same adhesive material to provide both strong bonding during processing and easy release afterward, eliminating the need to choose between strong bonding and easy debonding.
2Ease of operation
If the adhesive force is reduced to allow easy mechanical debonding, then the carrier can be separated after processing, but the adhesive force is not sufficient to straighten a warped wafer or hold it securely during processing steps
Solution Approach 1:
The adhesive's key parameter (adhesive force) is changed as a function of temperature. During processing at elevated temperatures, the adhesive force is high enough to provide reliable wafer stability and straighten warped surfaces. After processing, when cooled below 0°C, the adhesive force parameter automatically decreases to enable easy mechanical debonding. This dynamic parameter adjustment ensures both reliability during processing and ease of operation afterward.
Solution Approach 2:
The adhesive system transitions from a static, fixed-adhesion material to a dynamic system where adhesive force varies with temperature. This dynamic behavior allows the adhesive to adapt its bonding strength to the operational requirements: strong bonding during warm processing steps and weak bonding during cold storage and debonding operations, thereby ensuring both wafer stability and ease of separation.
3Strength
If a permanent adhesive is used to bond the carrier to the product substrate, then the bonding strength is sufficient to hold the wafer securely, but the adhesive force cannot be deactivated or reduced for easy separation
Solution Approach 1:
The permanent adhesive is modified to exhibit temperature-dependent adhesive force changes. At processing temperatures (above 0°C), the adhesive provides strong, permanent-like bonding to securely hold the wafer. At storage temperatures (below 0°C), the adhesive force parameter automatically reduces, enabling easy mechanical separation. This temperature-triggered parameter change allows the adhesive to function as a permanent adhesive during processing while facilitating easy debonding afterward.
Solution Approach 2:
The adhesive undergoes a phase transition in its bonding characteristics triggered by temperature change. The transition from high-adhesion phase (above 0°C) to low-adhesion phase (below 0°C) enables the adhesive to provide permanent-like bonding strength during processing while allowing easy separation after cooling, effectively combining the advantages of both permanent and temporary adhesives.
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 solution enhances the bonding strength between the carrier and product substrate while allowing for controlled debonding, ensuring stability during processing and easy separation, thus addressing the limitations of existing temporary adhesives.
Implementation Method 1
an adhesive component having a first coefficient of thermal expansion and a filler material having a second coefficient of thermal expansion. The second coefficient of thermal expansion is smaller than the first coefficient of thermal expansion. An adhesive force of the temporary adhesive weakens at a temperature below 0° C.
Data Source
AI summary
A method for handling a product substrate includes bonding a carrier to the product substrate by: applying a layer of a temporary adhesive having a first coefficient of thermal expansion onto a surface of the carrier; and bonding the carrier to the product substrate using the applied temporary adhesive. A surface of the temporary adhesive is in direct contact to a surface of the product substrate. The temporary adhesive includes or is adjacent a filler material having a second coefficient of thermal expansion which is smaller than the first coefficient of thermal expansion, so that stress occurs inside the temporary adhesive layer or at an interface to the product substrate or the carrier during cooling down of the temporary adhesive layer.