Semiconductor Package Warpage Control via Two-Stage Bonding
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Solution Overview
Problem
Conventional flip chip packaging methods face challenges with warpage due to thermal expansion differences between semiconductor chips and sealing materials, leading to over-molding issues and connection failures.
Innovation Solution
A method involving press-bonding semiconductor chips and substrates with a semiconductor adhesive at a temperature below the metal's melting point, followed by sealing and then heating above the melting point to form a metallic bond, thereby suppressing warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heating is performed above the melting point of metal to form a metallic bond, then connection reliability is improved, but warpage occurs due to thermal expansion differences
Solution Approach 1:
The heating process is divided into two distinct stages: a first heating stage at a temperature below the melting point of the metal for initial bonding, and a second heating stage at or above the melting point for forming the metallic bond. This segmentation allows the package to undergo thermal expansion in controlled steps, reducing overall warpage while still achieving reliable metallic connections.
Solution Approach 2:
The first heating stage performs a preliminary bonding action before the final metallic bond formation. By initially bonding the semiconductor chip to the substrate at a lower temperature, the structure is pre-stabilized, and subsequent heating to the melting point causes minimal additional warpage while still achieving the desired connection reliability.
2Shape
If heating is performed below the melting point of metal for initial bonding, then warpage is reduced, but metallic bond formation is insufficient
Solution Approach 1:
The bonding process continues through two sequential heating stages without interruption. The first stage establishes initial contact and bonding, and the second stage completes the metallic bond formation by heating to or above the melting point. This continuous process ensures both low warpage and high connection reliability are achieved.
Solution Approach 2:
The temperature parameter is changed in two distinct steps: first heating to a temperature below the melting point for initial bonding, then increasing to or above the melting point for metallic bond formation. This parameter change strategy allows the system to achieve both low warpage and high connection reliability by optimizing temperature at each stage.
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 method effectively reduces warpage and ensures reliable connections by forming a metallic bond after initial sealing, enhancing the stability and integrity of semiconductor packages.
Implementation Method 1
press-bonding the semiconductor chip and the substrate to each other with a semiconductor adhesive
Implementation Method 2
heating the sealed body at a temperature equal to or higher than a melting point of the metal of the connection portion to form a metallic bond
Implementation Method 3
warpage may occur in the semiconductor package after press-bonding, due to a difference in coefficients of thermal expansion between the chip and the sealing material for semiconductor
Data Source
AI summary
There is disclosed a method for manufacturing a semiconductor device comprising a semiconductor chip having a connection portion and a wiring circuit board having a connection portion, the respective connection portions being electrically connected to each other, or a semiconductor device comprising a plurality of semiconductor chips having connection portions, the respective connection portions being electrically connected to each other. The connection portions consist of metal. The above described method comprises: (a) a first step of press-bonding the semiconductor chip and the wiring circuit board or the semiconductor chips to each other so that the respective connection portions are in contact with each other with a semiconductor adhesive interposed therebetween, at a temperature lower than a melting point of the metal of the connection portion, to obtain a temporarily connected body; (b) a second step of sealing at least a part of the temporarily connected body with a sealing resin to obtain a sealed temporarily connected body; and (c) a third step of heating the sealed temporarily connected body at a temperature equal to or higher than the melting point of the metal of the connection portion, to obtain a sealed connected body.