Thin Die Packaging Using Dummy Wafer and Encapsulant Ratio
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Solution Overview
Problem
Thin semiconductor die used in reconstituted wafers tend to warp during redistribution layer formation, and backgrinding processes can contaminate and degrade the semiconductor material, necessitating a method to control warpage and protect the die.
Innovation Solution
The use of modular interconnect units with dummy semiconductor wafers and encapsulant to form a reconstituted wafer that includes thin semiconductor die, where the dummy die and encapsulant ratio is controlled to reduce warpage and protect the semiconductor die during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If thin semiconductor die are used in reconstituted wafers, then the package thickness is reduced, but warpage occurs during redistribution layer formation
Solution Approach 1:
The patent changes the physical state and properties of the carrier wafer by transforming it into a reconstituted wafer structure. This involves depositing encapsulant material over the carrier wafer and semiconductor die to form a new composite structure with different mechanical properties that can accommodate thin die without warping during RDL formation.
Solution Approach 2:
The patent creates a composite structure consisting of the carrier wafer, encapsulant material, and semiconductor die. This composite reconstituted wafer combines materials with different mechanical properties to achieve overall structural stability while maintaining thin profile, preventing warpage during subsequent processing steps.
2Length of stationary object
If backgrinding is performed to thin the die, then the desired thickness is achieved, but the semiconductor die becomes exposed and contaminated
Solution Approach 1:
The patent performs preliminary encapsulation of the semiconductor die before the thinning process. By depositing encapsulant material over the die initially, the die surface is protected from contamination during subsequent backgrinding operations. The encapsulant acts as a protective barrier that remains in place throughout the thinning process.
Solution Approach 2:
The encapsulant material serves as an intermediary protective layer between the semiconductor die and the grinding environment. This intermediate layer prevents direct contact between the die surface and contaminants generated during backgrinding, while still allowing the grinding process to achieve the desired thickness.
3Length of stationary object
If backgrinding is performed to reduce die thickness, then the desired thickness is achieved, but the strength of the semiconductor material is degraded
Solution Approach 1:
The patent applies preliminary encapsulation before the thinning process to protect the die surface. This protective layer allows the backgrinding process to proceed while minimizing mechanical stress and damage to the semiconductor material, preserving its structural integrity and strength even as thickness is reduced.
Data Source
AI summary
A semiconductor device has a carrier and a semiconductor die disposed over the carrier. A dummy die is disposed over the carrier as well. A first encapsulant is deposited over the semiconductor die and dummy die. The dummy die and a first portion of the first encapsulant is backgrinded while a second portion of the first encapsulant remains covering the semiconductor die. Backgrinding the dummy die fully removes the dummy die while the second portion of the first encapsulant remains covering the semiconductor die. A second encapsulant is optionally deposited over the dummy die prior to disposing the dummy die over the carrier. A conductive pillar is optionally formed over the dummy die prior to depositing the second encapsulant. The carrier is removed to expose an active surface of the semiconductor die. A build-up interconnect structure is formed over the active surface after removing the carrier.