Thin Wafer Support Assembly Using Double-Sided Release Tape
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Solution Overview
Problem
Thin semiconductor wafers with thicknesses less than 250 μm are unstable, prone to breaking, and difficult to handle due to their non-planar profile, which affects the throughput and uniformity of ion implantation processes in existing semiconductor fabrication tools.
Innovation Solution
A wafer assembly is formed by bonding a thin target wafer to a support wafer using double-sided release tape, allowing existing handling tools to accommodate and process the thin wafers without damage, ensuring stability and flatness for uniform doping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thin wafers are processed without support, then processing time is reduced, but wafer stability and flatness deteriorate causing breakage and non-planar profiles
Solution Approach 1:
A support wafer is introduced as an intermediary substrate to bond with the thin target wafer. This mediator provides the necessary mechanical support and flatness during handling and processing, preventing breakage and sagging while allowing the thin wafer to maintain its intended thin profile for the actual device structure.
Solution Approach 2:
The invention creates a composite wafer structure by bonding the thin target wafer to a thicker support wafer. This composite structure combines the advantages of both substrates: the thin wafer provides the desired device characteristics while the support wafer provides mechanical stability and flatness during processing.
2Shape
If electrostatic clamps are used to retain thin wafers, then wafer flatness is improved, but retention force is insufficient due to low current requirements
Solution Approach 1:
The support wafer acts as a mediator that eliminates the need for electrostatic clamps to provide both flatness and retention force. The mechanical bonding through the tape provides sufficient retention force while the support wafer itself maintains the flatness, separating these two functions.
3Ease of operation
If thin wafers are placed in existing wafer carriers, then wafer handling is simplified, but wafer sagging occurs limiting stackability
Solution Approach 1:
By creating a composite structure with a support wafer, the assembly gains sufficient rigidity to be handled in existing carriers without sagging. The support wafer provides the structural integrity needed for proper stacking and handling while the thin target wafer maintains its functional properties.
4Area of stationary object
If larger diameter wafers are used, then device performance is improved, but wafer strength decreases making them prone to breaking
Solution Approach 1:
The invention enables the use of larger diameter wafers by creating a composite structure where a thin large-diameter target wafer is bonded to a support wafer. The support wafer provides the necessary strength to prevent breaking during handling while the large-diameter target wafer maintains the desired device performance characteristics.
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 wafer assembly enables stable handling and processing of thin wafers, preventing sagging and breakage, and allows for efficient transfer and implantation without compromising the profile of the thin wafers, thereby improving the throughput and reliability of semiconductor device fabrication.
Implementation Method 1
bonded together using a double sided release tape
Data Source
AI summary
A semiconductor wafer assembly formed by bonding a support wafer to a thin wafer using a double-sided bonding release tape. The support wafer provides support for the thin target wafer such that existing handling tools can accommodate transporting and processing the assembly without compromising the profile of the thin target wafer.