Wafer Shape Pairing for Post-Bond Overlay and Yield Control
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Solution Overview
Problem
Existing wafer-to-wafer bonding methods face challenges with high-density interconnection due to wafer warpage and surface roughness, leading to suboptimal post-bonding performance and increased yield loss, as generic bonding recipes are not tailored to individual wafer shapes.
Innovation Solution
A system and method for wafer pairing that involves measuring and grouping wafers based on shape characteristics, applying customized reference recipes, and providing feedback/adjustments to improve bonding accuracy and reduce defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If generic bonding recipes are used for all wafers, then the bonding process is simple and fast, but post-bonding performance deteriorates due to unoptimized overlay and defects from uncontrolled wafer warpage
Solution Approach 1:
The patent segments the bonding process by dividing wafers into different groups based on their shape characteristics (e.g., bow, warp, curvature). Each group is then assigned a customized bonding recipe optimized for its specific shape profile. This segmentation allows precise control over wafer bonding parameters such as temperature, pressure, and bonding speed for each group, thereby improving post-bonding overlay precision while managing complexity through systematic categorization.
Solution Approach 2:
The patent implements parameter changes by adjusting bonding process parameters (temperature, pressure, time, bonding speed) based on the measured shape characteristics of different wafer groups. Each wafer group receives tailored parameter settings that compensate for its specific warpage and curvature, optimizing the bonding outcome for each group while maintaining overall process efficiency.
2Manufacturing precision
If wafer thickness is decreased to improve device density, then feature density increases, but wafer warpage becomes more pronounced and uncontrolled
Solution Approach 1:
The patent applies preliminary action by measuring and characterizing wafer shape parameters (bow, warp, curvature) before the bonding process. This pre-characterization allows the system to predict potential warpage issues and assign appropriate bonding recipes in advance, compensating for the increased susceptibility to warpage in thinner wafers before bonding occurs.
Solution Approach 2:
The patent uses parameter changes by modifying bonding process parameters based on the measured shape characteristics of thin wafers. For wafers with higher susceptibility to warpage, the system adjusts parameters such as bonding temperature, pressure profile, and bonding speed to minimize warpage effects and maintain shape control during the bonding process.
3Productivity
If advanced packaging approaches are implemented to improve feature density, then interconnect density increases, but yield loss increases due to suboptimal post-bonding performance
Solution Approach 1:
The patent implements feedback by using measured wafer shape data from metrology tools to inform the bonding process decisions. The system continuously monitors wafer characteristics, compares them against target specifications, and adjusts bonding recipe selection accordingly. This closed-loop feedback mechanism ensures that each wafer group receives optimal bonding parameters, minimizing defects and improving yield while maintaining high interconnect density.
Data Source
AI summary
A system for wafer pairing for wafer-to-wafer bonding may include a wafer shape metrology sub-system and controller. The controller may receive the shape measurements for a set of top wafers and bottom wafers and then sort the set of top wafers and the bottom wafers into wafer groups based on the shape measurements. The controller may tag each top and bottom wafer with a wafer group number and determine wafer pairs from selected wafer groups. The controller may calculate the bow difference for each wafer pair of the set of wafer pairs and sort the set of wafer pairs into wafer pair groups based on intervals of bow difference. The controller may associate each wafer pair group with a corresponding reference recipe and direct a bonder to bond the wafer pairs in a selected wafer pair group according to a corresponding reference recipe associated with the selected wafer pair group.