Wafer Bonding Alignment via Dual-Stage Mark Detection
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Solution Overview
Problem
The increasing diameter of semiconductor wafers leads to positional deviations during substrate bonding, resulting in alignment errors that cannot be ignored, particularly due to electrostatic adsorption between the wafer and the holder, affecting the precision of semiconductor device assembly.
Innovation Solution
A substrate bonding apparatus with a first and second stage, each holding a substrate, equipped with position measuring and detection systems to align and bond substrates with high precision by measuring and detecting fiducial and alignment marks, allowing for precise overlaying of substrates within a two-dimensional plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the diameter of semiconductor wafers is increased to improve mounting area efficiency, then the mounting area efficiency is improved, but positional deviation occurs during substrate bonding due to electrostatic adsorption
Solution Approach 1:
The patent applies preliminary action by measuring the positions of alignment marks on the wafer before substrate bonding occurs. The position measuring system captures the initial positions of alignment marks on both the first and second wafers, and the holder before bonding. This pre-measurement allows the system to calculate positional deviations caused by electrostatic adsorption during bonding and compensate for them in advance, thereby maintaining high alignment precision even with larger diameter wafers.
Solution Approach 2:
The patent implements feedback by using the measured positions of alignment marks to calculate and compensate for positional deviations. The position measuring system provides feedback information about the actual positions of alignment marks, which is then used to adjust the alignment calculation. This feedback mechanism allows the system to account for the effects of electrostatic adsorption and achieve accurate alignment despite the increased wafer diameter.
2Ease of operation
If dual-field camera or dual-field microscope is used to detect fiducial marks for alignment, then alignment technology is provided, but alignment error cannot be ignored due to positional deviation between wafer and holder
Solution Approach 1:
The patent introduces an intermediary approach by using alignment marks formed on the wafer surfaces themselves as reference points, rather than relying solely on fiducial marks on the holder. The position measuring system detects these alignment marks directly on the wafers, and the computational system uses these measurements to determine the relative positions of the wafers. This intermediary method of using wafer-based alignment marks compensates for the positional deviation between wafer and holder, achieving higher alignment precision.
Solution Approach 2:
The patent replaces the mechanical alignment system (relying on physical fiducial marks on holders) with an optical measurement system. Instead of using mechanical fixtures and fiducial marks mounted on holders, the system uses optical fields from the position measuring system to detect alignment marks on the wafer surfaces. This substitution allows for more precise measurement and compensation of positional deviations, reducing alignment errors.
Data Source
AI summary
A substrate bonding apparatus is equipped with a first table that holds one wafer of two wafers, a stage device that holds the other wafer in an orientation capable of opposing to the one wafer and that is movable at least within an XY plane, an interferometer system that measures positional information of the stage device within the XY plane, a first mark detection system that can detect subject marks including alignment marks on the other wafer held by the stage device, and a second mark detection system fixed to a part (the second table) of the stage device that can detect subject marks including alignment marks on the one wafer held by the first table.