Wafer Bonding System Contour Adjustment for Planarity
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving uniform wafer thinning due to uneven planarity and thickness variations during the bonding process of semiconductor substrates, leading to issues like non-bonding and shorting of through silicon vias (TSVs), which affect yield and reliability.
Innovation Solution
The solution involves modifying the bonding system by reshaping the upper and lower plates to compensate for non-uniformity, using shims and height adjusters to ensure even force distribution, and employing zoned temperature control to improve planarity and reduce total thickness variation (TTV) across the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If wafer backside thinning is performed to obtain thinner chips, then chip thickness is reduced, but planarity uniformity deteriorates causing total thickness variation
Solution Approach 1:
The bonding system applies different forces to different regions of the wafer through strategically positioned force application points. This local差异化 force application compensates for the non-uniform material removal during thinning, maintaining planarity uniformity across the wafer surface while achieving the required thin chip thickness.
Solution Approach 2:
The system dynamically adjusts bonding parameters including force magnitude, temperature distribution, and pressure application patterns during the bonding process. These parameter changes enable compensation for thickness variations introduced by backside thinning, ensuring uniform planarity while achieving target chip thickness.
2Ease of manufacture
If conventional bonding systems are used without modification, then bonding process is simple, but non-uniform force distribution causes TSV shorting and non-bonding
Solution Approach 1:
The bonding system divides the force application into multiple discrete points rather than uniform distributed pressure. This segmentation allows independent control of force at each bonding location, ensuring adequate force reaches TSV regions while preventing excessive force that could cause shorting, thereby improving TSV connectivity reliability.
Solution Approach 2:
The system incorporates sensors and control mechanisms that monitor bonding conditions in real-time and adjust force and temperature parameters accordingly. This feedback control ensures optimal bonding pressure is applied to maintain TSV connectivity without causing shorting, improving reliability while maintaining process automation.
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 significantly reduces total thickness variation, preventing over-thinning or over-polishing, thereby ensuring proper bonding and connectivity of TSVs, enhancing yield and reliability by maintaining uniformity and planarity post-thinning.
Implementation Method 1
using shims and height adjusters to ensure even force distribution
Implementation Method 2
employing zoned temperature control to improve planarity and reduce total thickness variation
Data Source
AI summary
A method of wafer bonding includes bonding a wafer to a carrier in a bonding system. The method further includes measuring thickness profile of the bonded wafer. The method further includes modifying surface contours of at least one of an upper plate or a lower plate of the bonding system during a bonding operation to improve planarity of bonded wafers based on the measured thickness profile, wherein modifying the surface contours of at least one of the upper plate or the lower plate comprises modifying the surface contours using a plurality of height adjusters.