Film-Type Wafer Mold Material Reduces Warp in Large-Diameter Thin-Film Wafers
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Solution Overview
Problem
Current wafer molding technologies face challenges with large-diameter thin-film wafers, including warping and difficulty in controlling the molding process, especially with increased diameter and reduced thickness, which affects transference performance and leads to issues like short shots and warp in semiconductor devices.
Innovation Solution
A film-type wafer mold material is developed, comprising a resin layer with a filler and at least one of acrylic, silicone, urethane, or polyimide silicone resins, formed into a film-like shape, with a thickness of 20 microns to 500 microns, and a storage elastic modulus of less than 1 GPa, which is applied to the wafer with a support and protective film to enhance transference and reduce warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a hardening adhesive sheet with epoxy resin is used for wafer sealing, then the transference performance is improved, but the warp of the wafer after molding increases due to large hardening shrinkage
Solution Approach 1:
The patent changes the chemical composition parameters of the resin by using a silicone resin with epoxy group instead of conventional epoxy resin, which has different shrinkage characteristics during hardening. This parameter change reduces the hardening shrinkage and consequently suppresses wafer warp while maintaining transference performance
Solution Approach 2:
The patent creates a composite material system by combining silicone resin with epoxy group, filler, and curing agent. This composite formulation achieves a balance between transference performance and warp suppression by leveraging the low shrinkage property of silicone resin while maintaining adhesion through the epoxy group
2Area of stationary object
If the wafer diameter is increased and thickness is reduced, then the sealing area is increased, but the control of molding process becomes difficult and short shots occur
Solution Approach 1:
The patent changes the viscosity and flow characteristics parameters of the molding material by selecting appropriate filler content and resin type. This enables the material to flow properly into narrow portions and large sealing areas while maintaining control over the molding process, preventing short shots even with increased wafer size
3Shape
If a film-type mold material with low storage elastic modulus is used, then the warp is reduced, but the structural strength may be compromised
Solution Approach 1:
The patent develops a composite material where silicone resin with epoxy group is combined with specifically selected fillers. This composite structure provides both the low elastic modulus needed for warp reduction and sufficient structural strength through the reinforcement provided by the filler particles
Solution Approach 2:
The patent applies different material properties to different aspects of the mold material: the silicone resin matrix provides low elastic modulus for warp reduction, while the filler particles provide local reinforcement for structural strength. This local differentiation of material quality resolves the contradiction between flexibility and strength
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 solution provides excellent transference performance, reduces warping, and ensures low-stress properties, enabling efficient collective molding of large-diameter thin-film wafers with improved handling and cutting precision in semiconductor apparatus manufacturing.
Implementation Method 1
a resin layer containing a filler and at least any one of an acrylic resin, a silicone resin having an epoxy group, an urethane resin, and a polyimide silicone resin
Data Source
Figure 1
Figure 2(A)~2(F)
AI summary
The invention provides a wafer mold material for collectively subjecting a wafer having semiconductor devices on a surface thereof to resin molding, wherein the wafer mold material has a resin layer containing a filler and at least any one of an acrylic resin, a silicone resin having an epoxy group, an urethane resin, and a polyimide silicone resin, and the wafer mold material is formed into a film-like shape. There can be a wafer mold material that enables collective molding (wafer molding) with respect to a wafer having semiconductor devices formed thereon, has excellent transference performance with respect to a large-diameter thin-film wafer, can provide a flexible hardened material with low-stress properties, and can be preferably used as a mold material in a wafer level package with less warp of a formed (molded) wafer.