Semiconductor Device Dual-Thickness Electrode Stress Management
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Solution Overview
Problem
Existing semiconductor device manufacturing techniques face challenges in minimizing damage to the semiconductor substrate and wafer warping due to stress from bonding wires, as increasing the dummy cell region ratio or electrode thickness can lead to increased device size and thermal expansion issues.
Innovation Solution
A semiconductor device with a dual-thickness upper surface electrode, where a bonding wire is bonded to a thicker second thickness region, reducing stress and preventing damage, while maintaining a thinner first thickness region to prevent wafer warping, and optionally incorporating a slit portion to further mitigate warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the entire upper surface electrode is increased to relax stress in the bonded portion, then stress relaxation is improved, but the semiconductor wafer tends to warp during manufacturing steps
Solution Approach 1:
The upper surface electrode is designed with different thicknesses in different regions: a first thickness in the element region and a second greater thickness in the bonding region. This local variation allows the electrode to provide stress relaxation where needed (in the bonding region) while maintaining wafer stability in the element region, thereby resolving the contradiction between stress relaxation and wafer warping prevention.
2Reliability
If a dummy cell region is created for bonding, then damage to the cell region is controlled, but the ratio of cell region to substrate area decreases and the device size increases
Solution Approach 1:
The electrode thickness is locally increased only in the bonding region where the bonding wire is attached, while the element region maintains its original thinner electrode structure. This allows bonding to be performed directly on the element region without requiring a separate dummy cell region, thereby controlling damage to cells while maintaining a compact device size.
3Stability of the object's composition
If the upper surface electrode has a thinner first thickness region, then wafer warping is suppressed, but stress relaxation in the bonding area is reduced
Solution Approach 1:
The electrode is designed with spatially varying thickness: thinner in the element region to suppress wafer warping, and thicker in the bonding region to provide stress relaxation. This local differentiation allows both requirements to be satisfied simultaneously in their respective regions.
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
This design enhances the breakdown resistance of the semiconductor device and prevents wafer warping during manufacturing by relaxing stress in the bonding area and allowing for a more compact device design.
Implementation Method 1
the second thickness region is thicker than the first thickness region, stress, generated on the second thickness region due to bonding the bonding wire, is relaxed
Implementation Method 2
the thermal expansion coefficient of the upper surface electrode and that of the semiconductor substrate are different, therefore defects tend to occur
Data Source
AI summary
A semiconductor device disclosed in this description has a semiconductor substrate including an element region in which a semiconductor element is formed, and an upper surface electrode formed on an upper surface of the element region of the semiconductor substrate. The upper surface electrode has a first thickness region and a second thickness region which is thicker than the first thickness region, and a bonding wire is bonded on the second thickness region.