UV-Release Bonding Layer for Thin Die Handling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor fabrication methods and RFID device production face challenges in efficiently producing small-dimensioned individual dies and integrating them into compact RFID tags with foldable tabs, particularly due to limitations in handling and processing tiny dielets.
Innovation Solution
The method involves using a UV-transmissive handler with a bonding layer that includes both an adhesive and a UV-sensitive ablation layer, allowing for precise deep reactive ion etching and selective release of dies using UV radiation, enabling the formation of small dies and their precise placement on flexible substrates with integral antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional adhesive bonding is used for wafer handling, then wafer can be processed and thinned, but selective release of individual dies is not achievable
Solution Approach 1:
The bonding layer is segmented into functionally distinct layers: a UV-transparent adhesive layer for bonding and a UV-absorbing release layer for selective die release. This segmentation allows independent optimization of each layer's properties to achieve both strong bonding and precise selective release of individual dies.
Solution Approach 2:
The UV-absorbing release layer acts as an intermediary between the UV radiation and the adhesive layer. It absorbs UV energy and converts it to localized heat or mechanical stress, mediating the energy transfer to achieve controlled die release without damaging the underlying circuitry.
2Manufacturing precision
If deep reactive ion etching is used for singulation, then precise trench formation is achieved, but handling of small dies becomes difficult
Solution Approach 1:
The bonding layer is designed with preliminary considerations for post-singulation handling. The UV-release functionality is built into the bonding structure before singulation, enabling easy die release and handling after precise DRIE trench formation, thus resolving the handling difficulty of small precision-cut dies.
3Length of moving object
If wafer thickness is reduced to 200 μm or less, then small die dimensions are achieved, but mechanical strength decreases
Solution Approach 1:
The bonding and release process parameters are optimized for thin wafers. The UV radiation parameters (wavelength, intensity, duration) are specifically tuned to release adhesion in ultra-thin wafers without causing mechanical failure, enabling handling of 200 μm or thinner wafers that would be too fragile for conventional processing.
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
This approach facilitates the production of RFID tags with small dimensions and foldable tabs that can contact the top surface of dies, enabling precise handling and integration of small dielets, which is not feasible with conventional processing methods.
Implementation Method 1
a bonding layer that bonds the handler to the device wafer
Implementation Method 2
at least part of the bonding layer is subjected to UV radiation through the UV-transmissive handler. Fluence of selected energy is released in a spot within the bonding layer
Implementation Method 3
singulating the device wafer using deep reactive ion etching, thereby forming a plurality of dies separated by trenches extending completely through the device wafer
Data Source
AI summary
Deep reactive ion silicon etching of a device wafer, laser-induced release of individual dies, and individual placement of the dies on flexible substrates facilitate formation of circuits having relatively large external inductors for powering devices such as RFID devices. Small flexible tabs enable die-inductor connection. The absorption properties of both an adhesive layer and an ablation layer may be employed to facilitate debonding of individual dies from a glass handler without damaging integrated circuits associated with the dies. Die packs including cavities for accepting individual dies facilitate fabrication processes using dies having small dimensions.