Pre-sintered Semiconductor Die Structure for Stable Positioning
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Solution Overview
Problem
Conventional sintering techniques using wet silver pastes result in the formation of drying channels during the sintering process, degrading the thermal and electric properties of the sintered silver layer and making it difficult to maintain the position of dies on the substrate due to poor adhesion after solvent evaporation.
Innovation Solution
A method involving a dried sintering material with sintering particles and a solvent, where the substrate is preheated below the sintering temperature to form local sinter connections between particles, providing a stable joint to fix the die in place before full sintering, allowing for transport to sintering equipment without displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wet silver paste is used for die attachment, then adhesion is sufficient to hold dies to substrate, but drying channels form during sintering that degrade thermal and electric properties
Solution Approach 1:
The patent applies preliminary action by pre-heating the substrate to form a stable joint that fixes the die to the substrate before the actual sintering process. This preliminary fixation prevents die displacement during transport and positioning, while the controlled heating approach avoids forming harmful drying channels that would degrade thermal and electric properties.
2Strength
If solvent is removed from sintering paste by drying at elevated temperature, then adhesion qualities improve for holding dies in position, but the paste becomes difficult to apply and maintain position during transport
Solution Approach 1:
The patent applies parameter changes by controlling the heating temperature to be below the evaporation temperature of the solvent during the preliminary fixation stage. This temperature parameter control allows the paste to maintain sufficient adhesion to hold dies in position while avoiding complete solvent evaporation that would make the paste difficult to apply and handle during transport.
3Strength
If complete sintering is performed immediately, then strong metallurgical bonds are formed, but die positioning becomes difficult to maintain during transport to sintering equipment
Solution Approach 1:
The patent applies segmentation by dividing the sintering process into two distinct stages: a preliminary fixation stage that forms a stable joint to secure die positioning, and a subsequent complete sintering stage that forms strong metallurgical bonds. This process segmentation allows each stage to optimize for its specific function - positioning stability in the first stage and bond strength in the second 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 approach ensures stable positioning of dies on the substrate during transport and subsequent sintering, enhancing the reliability and adhesion of the sintered connection while maintaining the integrity of thermal and electric properties.
Implementation Method 1
heating the substrate to a temperature below a sintering temperature of the dried sintering material while the semiconductor die is pressed against the substrate to form local sinter connections between adjacent ones of the sintering particles
Implementation Method 2
during the subsequent sintering process, drying channels are formed as the organic composites evaporate
Data Source
AI summary
A sintered connection is formed by pressing a semiconductor die against a substrate with a dried sintering material interposed between the substrate and the semiconductor die, the dried sintering material having sintering particles and a solvent. The substrate is heated to a temperature below a sintering temperature of the dried sintering material while the semiconductor die is pressed against the substrate to form local sinter connections between adjacent ones of the sintering particles. The local sinter connections collectively provide a stable joint that fixes the semiconductor die to the substrate prior to sintering. A sintered connection is then formed between the semiconductor die and the substrate from the dried sintering material, after the stable joint is formed.