Wafer Bonding Apparatus with Localized Convex Support
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Solution Overview
Problem
The direct bonding method in semiconductor manufacturing often results in non-uniform stress and distortion in bonded wafers due to thermal and elastic distortions, leading to issues like expansion, contraction, and misalignment in the device layer, which affects the quality and productivity of CMOS image sensors.
Innovation Solution
A semiconductor manufacturing apparatus that uses a stage and pushers to support and align wafers without causing local elastic distortion, employing a pressure sensor to control the bonding process and maintain uniformity, ensuring that the bonding initiation point is formed without distorting the substrates, thus minimizing stress differences across the bonded surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the device wafer is sucked to the stage to correct warp, then the warp correction is achieved, but local elastic distortion occurs causing non-uniform stress and expansion/contraction in the bonded wafers
Solution Approach 1:
A convex support is introduced as an intermediary element between the stage and the device wafer. The convex support contacts the device wafer at a single point (bonding initiation point) rather than sucking the entire wafer surface to the stage. This mediator transfers the necessary mechanical support while minimizing elastic distortion, allowing warp correction without causing the non-uniform stress that leads to expansion and contraction in the bonded wafers.
Solution Approach 2:
Instead of applying uniform suction across the entire wafer surface, the invention applies localized support at a specific point (the bonding initiation point). This local quality approach means that only the necessary minimal area is contacted to initiate bonding propagation, thereby avoiding the widespread elastic distortion that would result from full-surface suction while still achieving the required warp correction.
2Strength
If pressure is applied to bring wafer surfaces into contact, then bonding is initiated, but elastic distortion of the wafer occurs causing non-uniform stress
Solution Approach 1:
Pressure is applied locally at the bonding initiation point through the convex support rather than uniformly across the entire wafer surface. This localized pressure application is sufficient to initiate hydrogen bonding at the contact point, which then propagates across the wafer interface. By concentrating the pressure at a single point rather than distributing it uniformly, the method achieves effective bonding while minimizing the elastic distortion that would result from broad pressure application.
3Strength
If the bonded wafers are heated to convert hydrogen bonding to covalent bond, then bonding strength increases, but thermal stress causes additional distortion
Solution Approach 1:
The bonding process is initiated at a single point through the convex support before heating is applied. This preliminary bonding action creates an anchored connection point that stabilizes the wafer structure. When heating is subsequently applied to convert hydrogen bonds to covalent bonds, the pre-established bonding point serves as a stable reference that minimizes the propagation of thermal stress-induced distortion across the wafer, allowing strength enhancement while maintaining shape stability.
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 reduces the variation in distortion by up to 40% compared to traditional methods, improving the alignment and uniformity of patterns on the bonded wafers and enhancing the overall quality and productivity of the semiconductor manufacturing process.
Implementation Method 1
This causes hydrogen bonding between a hydroxyl group and adsorbed water molecules on the surface of the two wafers. This bonding propagates from the contacted part and finally bonds the whole wafers.
Implementation Method 2
When the bonded wafers where the whole wafers are completely bonded are heated with a temperature of equal to or more than 200 to 400° C., this changes at least a part of the hydrogen bonding into a covalent bond such as Si—O—Si bond. This increases the bonding strength between the bonded wafers.
Data Source
AI summary
According to one embodiment, a semiconductor manufacturing apparatus is provided. The semiconductor manufacturing apparatus includes a stage, a substrate supporter, first and second pushers, and a controller. The stage is configured to support outer periphery portions of the first semiconductor substrate from below. The substrate supporter is configured to hold the back of the second semiconductor substrate. The first and second pushers are configured to bring the first and second semiconductor substrates in contact. The controller is configured to form the bonding initiation point between the first and second semiconductor substrates.