Through-Electrode Formation in Stacked Semiconductor Devices
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Solution Overview
Problem
The existing techniques for forming through-electrodes in semiconductor devices face challenges such as low processability of interlayer insulating films and difficulty in processing deep holes, which hinders the formation of high-aspect-ratio through-electrodes, leading to reduced productivity and performance in stacked semiconductor chips.
Innovation Solution
A semiconductor device configuration where a bump electrode with a protruding portion penetrates through the pad and interlayer insulating film, allowing the back-surface electrode to reach and connect with the bump electrode, reducing the processing complexity and increasing the aspect ratio of through-electrodes, thus enhancing performance without compromising productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If through-holes are formed deep in the silicon substrate to create high-aspect-ratio through-electrodes, then the electrical connection performance is improved, but the processing difficulty and time increase significantly
Solution Approach 1:
The through-electrode formation process is divided into two separate stages: first forming a bump electrode with protruding portion on the front surface, then forming a back-surface electrode on the rear surface that connects to the protruding portion. This segmentation avoids the need to process deep holes through the entire substrate thickness in one operation, thereby improving productivity while maintaining electrical connection performance.
Solution Approach 2:
The bump electrode with protruding portion is formed in advance on the front surface before substrate thinning and back-surface electrode formation. This preliminary action creates a ready-made connection structure that simplifies subsequent processing steps and enables faster through-electrode formation without compromising the final electrical connection quality.
2Ease of manufacture
If conventional through-electrode formation methods are used, then the process is simpler, but the aspect ratio of through-electrodes is reduced, affecting device performance
Solution Approach 1:
The invention transitions from forming through-electrodes by drilling deep holes from one surface to forming electrodes on both surfaces of a thinned substrate. By utilizing both the front and back surfaces of the substrate, the effective path length for electrical connection is increased without requiring excessively deep holes, thereby achieving higher aspect ratio through-electrodes while maintaining manufacturing feasibility.
3Reliability
If deep hole processing is performed on the back surface to reach bonding pads, then through-electrode connection is achieved, but bonding pads are damaged
Solution Approach 1:
The bump electrode with protruding portion is formed in advance on the front surface before substrate thinning. This preliminary formation creates a protective structure that extends into the substrate, allowing the back-surface electrode to connect to it without requiring deep hole processing that would damage the bonding pads on the front surface.
Solution Approach 2:
The protruding portion of the bump electrode acts as an intermediary structure that bridges the front surface bonding pad and the back-surface electrode. This intermediary enables electrical connection without requiring the back-surface processing to directly reach the bonding pad, thereby avoiding pad damage while achieving through-electrode connectivity.
Data Source
AI summary
In a semiconductor device in which a plurality of semiconductor chips are stacked, performance is enhanced without deteriorating productivity. The semiconductor device has a first semiconductor substrate having a first surface and a second surface opposite the first surface, a first insulating film formed on the first surface, a first hole formed in the first insulating film and partially extending into the first semiconductor substrate, a second hole formed in the second surface, a first electrode entirely filling the first hole, and a conductive film conformally formed in the second hole. The conductive film is electrically connected to a bottom surface of the first electrode and leaves a third hole in the first semiconductor substrate open. The third hole is configured to receive a second electrode of a second semiconductor substrate.