Bond Pad Sidewall Structure for Stable Low Parasitic Capacitance
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Solution Overview
Problem
Existing semiconductor devices face challenges in stabilizing the reduction of parasitic capacitance between electrodes and substrates, as previous methods either fail to reduce capacitance sufficiently or compromise stability.
Innovation Solution
A semiconductor device design featuring a bonding pad with side wall parts that create a gap region between the electrode and the insulating film, where the electrode is supported by these side wall parts and secondary fixing parts, allowing for stable reduction of parasitic capacitance by controlling the gap interval accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the electrode is placed away from the substrate in a cantilever manner, then parasitic capacitance is reduced, but stability of the interval is insufficient
Solution Approach 1:
The bonding pad is divided into multiple functional parts: fixing parts that contact the substrate, side wall parts that extend upward, and an electrode part that forms the capacitive element. This segmentation allows each part to perform its specific function - the fixing parts provide stable mechanical support while the electrode part maintains the capacitive gap, resolving the contradiction between capacitance reduction and stability.
Solution Approach 2:
The bonding pad structure transitions from a planar configuration to a three-dimensional structure by adding side wall parts that extend in the vertical dimension. This dimensional change enables the electrode to be positioned at a controlled height above the substrate, creating a stable gap for capacitance management while maintaining mechanical stability through the vertical side walls.
2Stability of the object's composition
If a polyimide tube is placed between the electrode and substrate, then mechanical stability is achieved, but parasitic capacitance cannot be reduced sufficiently
Solution Approach 1:
The problematic polyimide tube is extracted and replaced with a metal-based bonding pad structure. The side wall parts and electrode part are formed from metal layers that can be precisely controlled, eliminating the need for polyimide while achieving both mechanical stability and effective parasitic capacitance reduction through precise geometric control.
Solution Approach 2:
The structure transitions from using polyimide material to using metal layers with controlled thickness and dimensions. By changing the material parameter from polyimide to metal and controlling the geometric parameters (thickness, width, height) of the side wall and electrode parts, the design achieves both mechanical stability and reduced parasitic capacitance.
3Adaptability or versatility
If the electrode is configured to be elastically deformed, then flexibility is achieved, but stable interval positioning is compromised
Solution Approach 1:
The side wall parts act as pre-formed structural supports that cushion and constrain the electrode part, preventing excessive deformation during wire bonding. This beforehand structural support ensures that the electrode maintains its positioned gap with the substrate even under mechanical stress, achieving both flexibility for bonding and precision for gap control.
Data Source
AI summary
Provided here are: an electrically-conductive semiconductor substrate with which a semiconductor circuit is formed; an insulating film deposited on a major surface of the electrically-conductive semi-conductor substrate; and a bonding pad having fixing parts fixed onto the insulating film, side wall parts rising up from the fixing parts, and an electrode part connected to the side wall parts and disposed in parallel to the major surface; wherein the electrode part forms, together with the insulating film, a gap region therebetween, and portions of the electrode part where it is connected to the side wall parts are configured to have at least one of: a positional relationship in which they sandwich therebetween a central portion of the electrode part in its bonding region to be bonded to a bonding wire; and a positional relationship in which they surround the central portion.