Temporary Spacer Embedding Semiconductor Dies
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Solution Overview
Problem
Conventional film-assisted molding techniques face challenges in accommodating device height and size tolerances, leading to improper edge formation and increased costs due to the need for high force application, which results in reduced mechanical stability and long-term stability issues, especially when protecting small topological features or underfill compounds are used.
Innovation Solution
The introduction of a temporary spacer applied to the semiconductor die, which allows for adequate clearance of the embedding material over the die edge, protecting passivation and enabling the use of a standard film thickness without increasing lateral dimensions, thus avoiding the need for expensive special molding compounds and reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If film assisted molding is used to exclude areas from mold application, then the desired area protection is achieved, but high force must be applied resulting in improper edge formation and reduced mechanical stability
Solution Approach 1:
A temporary spacer is introduced as an intermediary element between the semiconductor die and the mold foil. The spacer has a height greater than the die thickness, creating a gap that allows the mold foil to exclude areas from molding without requiring excessive force. This mediator enables the foil to conform to the spacer's sidewall rather than pressing directly against the die, thus protecting both the area exclusion reliability and the mechanical stability of the die edge.
Solution Approach 2:
The solution transitions from a two-dimensional area exclusion problem to a three-dimensional solution by adding vertical height through the temporary spacer. The spacer's height dimension creates a lateral gap between the foil and the die periphery, allowing the molding process to exclude specific areas without applying high compressive force to the die. This dimensional addition resolves the conflict between area protection and mechanical stability.
2Manufacturing precision
If high force is applied to press the foil against the device, then mold flash is avoided, but improper edge formation occurs at topographical features
Solution Approach 1:
The temporary spacer serves as a mediator that absorbs the molding force. Instead of the mold foil pressing directly against the semiconductor die's topographical features, the foil contacts the spacer's sidewall. This intermediary structure distributes the applied force evenly along the spacer's vertical surface, preventing localized high pressure that would cause edge formation defects while still maintaining sufficient force to prevent mold flash.
Solution Approach 2:
The introduction of the temporary spacer changes the geometric parameters of the molding interface. By adding a structure with height greater than the die thickness, the spacer creates a larger vertical surface area for force distribution. This parameter change transforms the pressure distribution from concentrated at the die periphery to distributed along the spacer's sidewall, improving edge formation precision while reducing harmful pressure effects.
3Manufacturing precision
If underfill compound is applied or filler particle size is reduced, then embedding quality is improved, but mechanical stability and long-term stability are reduced
Solution Approach 1:
The temporary spacer is applied before the molding process to pre-establish the desired embedding geometry. By having the spacer in place during molding, the embedding material is guided to form precise features against the spacer's sidewall, achieving high manufacturing precision without requiring underfill compounds or fine filler particles. This preliminary structuring action enables good embedding quality while maintaining the stability of the embedding material composition.
4Quantity of substance
If standard film thickness is used, then material cost is reduced, but accommodating height and size tolerances becomes difficult
Solution Approach 1:
The temporary spacer adds a vertical height dimension that compensates for variations in die thickness and lateral dimensions. By having the spacer's height exceed the maximum die thickness, the system can accommodate a range of die sizes and tolerances while using a standard film thickness. The spacer's extra height creates sufficient gap space regardless of die variations, enabling tolerance accommodation without requiring variable film thicknesses or expensive custom materials.
Data Source
AI summary
A method includes: providing a semiconductor die having a first main surface, a second main surface opposite the first main surface, and an edge between the first main surface and the second main surface; applying a temporary spacer to a first part of the first main surface of the semiconductor die, the first part being positioned inward from a peripheral part of the first main surface; after applying the temporary spacer, embedding the semiconductor die at least partly in an embedding material, the embedding material covering the edge and the peripheral part of the first main surface of the semiconductor die and contacting a sidewall of the temporary spacer; and after the embedding, removing the temporary spacer from the first main surface of the semiconductor die to expose the first part of the first main surface of the semiconductor die. A semiconductor device produced by the method is also provided.