Multi-Wafer Front-Side Bonding Layout for Simpler 3D Stacking
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Solution Overview
Problem
The challenge in semiconductor manufacturing lies in unifying circuit design and process flow across stacked wafers, which increases process complexity and reduces structural flexibility, especially as the number of stacked wafers grows, due to the complexity of bonding sequences and interconnection layers in multi-chip stacking.
Innovation Solution
A method involving bonding the front sides of wafers face-to-face, forming interconnection layers, and flipping the structure to orient the wafers such that the front sides of all wafers at the bottom of the top wafer face upwards, allowing for unified circuit design and process flow, reduced complexity, and adjustable bonding sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multi-wafer stacking is achieved by bonding front sides of wafers face to face and forming bonding interfaces on back sides, then the number of stacked wafers can be increased, but the process complexity increases and structural flexibility decreases
Solution Approach 1:
The patent inverts the conventional bonding approach by bonding the front sides of wafers together instead of bonding back sides. This allows all wafers in the stack to have their front sides facing upward, enabling unified circuit design and process flow while reducing bonding interface complexity. The inversion of the bonding surface from back side to front side resolves the contradiction between stacking quantity and process complexity.
2Quantity of substance
If conventional bonding methods are used with bonding interfaces on back sides, then wafer stacking can be achieved, but circuit design unification and process flow unification become difficult
Solution Approach 1:
By bonding front sides of wafers together and having all front sides face upward, the patent enables unified circuit design and process flow across all wafers. This inversion approach allows consistent circuit orientation and simplified design methodology, resolving the contradiction between achieving wafer stacking and maintaining circuit design unification.
3Quantity of substance
If multiple bonding interfaces are formed on back sides of wafers, then multi-wafer stacking is achieved, but structural flexibility is reduced
Solution Approach 1:
The patent improves structural flexibility by bonding front sides of wafers together and orienting all front sides upward. This configuration allows easier access to bonding interfaces for additional wafer stacking and provides greater freedom in designing the stacking structure. The inverted bonding approach resolves the contradiction between achieving multi-wafer stacking and maintaining structural flexibility.
Data Source
AI summary
Disclosed in the present disclosure are a semiconductor device and manufacturing method thereof. The method comprises: bonding the front surface of a top wafer to the front surface of a first wafer, and enabling the front surface of the top wafer to face upwards and the front surface of the first wafer to face downwards; bonding the front surface of a second wafer to the back surface of the first wafer to form a bonding structure, and enabling the front surface of the second wafer to face downwards; flipping the bonding structure to enable the front surface of the first wafer and the front surface of the second wafer to face upwards, and forming a pad pin in a top chip substrate.