Semiconductor Feedthrough Electrodes for Miniaturization
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Solution Overview
Problem
The miniaturization of semiconductor devices is hindered by the large land area required for bonding thin metal wires, which also leads to deteriorated high-frequency characteristics due to parasitic inductances in these wires.
Innovation Solution
The use of feedthrough electrodes penetrating the semiconductor substrate to connect pad electrodes on the surface to backside electrodes, reducing the need for large land areas and minimizing parasitic inductances by providing shorter, thicker connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If thin metal wires are used to connect emitter electrodes to the land, then electrical connection is achieved, but the land area becomes excessively large (approximately 25 times the semiconductor device area)
Solution Approach 1:
The invention transitions from a two-dimensional wire bonding approach (metal wires on the surface) to a three-dimensional approach by forming feedthrough electrodes that penetrate through the semiconductor substrate thickness direction. This vertical connection path eliminates the need for large lateral land area, reducing the land to approximately the same size as the semiconductor device itself.
Solution Approach 2:
Instead of extending connections horizontally from the device edges to the land perimeter, the invention inverts the connection approach by penetrating vertically through the substrate. The feedthrough electrodes extend from the front surface through the substrate to the back surface, where they connect to backside electrodes, effectively inverting the traditional bonding geometry.
2Reliability
If long and thin metal wires are used for connection, then electrical connectivity is provided, but parasitic inductances increase and high-frequency characteristics deteriorate
Solution Approach 1:
The invention fundamentally changes the geometric parameters of the connection path: instead of long and thin wires with lengths of 1 mm and diameters of 25 μm, the feedthrough electrodes provide short and thick connections penetrating the substrate. This parameter change reduces parasitic inductance from being proportional to length and inversely proportional to diameter, significantly improving high-frequency characteristics at 1 GHz and above.
3Area of stationary object
If the land area is reduced to enable device miniaturization, then smaller circuit devices are achieved, but sufficient bonding area for wire connections cannot be ensured
Solution Approach 1:
The invention resolves the bonding area conflict by moving the connection interface to a different dimension. Instead of requiring large peripheral bonding areas on the front surface, the feedthrough electrodes create bonding interfaces on the back surface of the substrate, where space is abundant. This allows the front land area to be minimized to match the device size while maintaining sufficient bonding area on the backside.
Data Source
AI summary
Disclosed is a semiconductor device in which emitter pad electrodes connected to an active region, collector and base pad electrodes are formed on a surface of a semiconductor substrate. Furthermore, on a back surface of the semiconductor substrate, a backside electrode is formed. Moreover, the emitter pad electrodes connected to a grounding potential are connected to the backside electrode through feedthrough electrodes penetrating the semiconductor substrate in a thickness direction.