Compressed Ball Bonding Structure for Semiconductor Stacking
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Solution Overview
Problem
Conventional semiconductor packaging methods result in electrical defects due to high bonding structure heights, leading to short circuits when semiconductor chips are vertically stacked on a wiring board.
Innovation Solution
A method of forming a bonding structure with a compressed ball and wire, where a ball is formed at the end of a wire, attached to a bonding pad, and compressed to create a neck portion, resulting in a compressed ball with a height of 20 to 25 μm, which covers the pad and has a wrinkle on its surface, reducing the overall height and preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding structures are used with height above 30 μm, then the bonding process is simpler, but electrical short circuits occur between bonding structures when chips are vertically stacked
Solution Approach 1:
The patent changes the height parameter of the bonding structure from above 30 μm to 20-25 μm through a multi-step compression process. This parameter change resolves the contradiction by reducing the height to prevent short circuits while maintaining bonding functionality through controlled deformation and neck portion formation.
Solution Approach 2:
The patent performs preliminary compression of the ball before final bonding, creating a compressed ball with reduced height and a neck portion. This preliminary action prepares the bonding structure for vertical stacking by pre-reducing its height, thereby preventing future short circuits while maintaining bonding integrity.
2Reliability
If the bonding structure height is reduced to 20-25 μm, then short circuits are prevented, but the forming process becomes more complex
Solution Approach 1:
The bonding process is segmented into distinct stages: initial ball formation, first compression to create preliminary compressed ball, neck portion formation, second compression to create compressed ball, and final bonding. This segmentation makes the complex process manageable and controllable, resolving the contradiction between reduced height and process complexity.
Solution Approach 2:
The patent employs dynamic control of the compression process with multiple stages of compression and release, allowing the ball to transform through different shapes (spherical → preliminary compressed → necked → compressed). This dynamic approach enables precise height control to 20-25 μm while managing process complexity through controlled transformations.
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
The reduced height of the bonding structure minimizes electrical defects caused by short circuits, allowing for more reliable connections and increased integration of semiconductor chips without electrical defects.
Implementation Method 1
vertically moving the ball, the wire, and the capillary downwardly to attach the ball to one side of a first pad
Implementation Method 2
pressing the capillary against a center of the ball to form a preliminary compressed ball and a neck portion extending from the preliminary compressed ball
Implementation Method 3
obliquely moving the capillary downwardly with respect to the neck portion to compress the neck portion toward an edge of the preliminary compressed ball to form a compressed ball, the compressed ball substantially covering an entire surface of the first pad and having a wrinkle on an upper surface thereof
Data Source
AI summary
A method of forming at least one bonding structure may be provided. A ball may be formed on the front end of a wire outside a capillary. The capillary may be moved downwardly to form a preliminary compressed ball on a first pad using the ball. The capillary may be moved upwardly to form a neck portion on the preliminary compressed ball using the preliminary compressed ball and the wire. The capillary may be moved obliquely and downwardly to form a compressed ball. The capillary may extend the wire from the compressed ball to a second pad.