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Solution Overview
Problem
Silicon Carbide (SiC) power devices face challenges in combining materials with different properties to achieve sufficient adhesion and moisture resistance, making it difficult to meet high voltage ruggedness and moisture resistivity requirements, which is crucial for achieving MSL level 1 certification.
Innovation Solution
A semiconductor device is proposed with a lead frame, semiconductor chip, and a mold, where an adhesion promoter is applied to specific surfaces of the lead frame and chip to enhance adhesion between the mold and the materials, using silane-based, metal oxide dendrite, or PI-based adhesion promoters, and an additional promoter is applied between passivation layers to ensure robust adhesion across interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different materials with different properties are used for SiC product architecture, then material spectrum and functionality are improved, but adhesion and hermeticity against humidity and moisture deteriorate
Solution Approach 1:
An adhesion promoter layer is introduced as an intermediary between the mold compound and the underlying materials (lead frame, semiconductor chip, passivation layers). This intermediate layer specifically addresses the adhesion problems caused by combining diverse materials with different surface properties, enabling reliable bonding across the heterogeneous material interface without compromising the material spectrum flexibility.
Solution Approach 2:
The solution employs a composite structure where the adhesion promoter layer combines specific chemical components (such as silane-based compounds, metal oxide dendrites, or PI-based materials) to create a multi-functional interface layer that provides both adhesion promotion and moisture barrier properties, resolving the contradiction between material diversity and interface reliability.
2Reliability
If adhesion promoter is applied to enhance mold adhesion, then adhesion between mold and materials is improved, but device complexity increases
Solution Approach 1:
The adhesion promoter is applied in advance to the surfaces (lead frame second frame surface, semiconductor chip second chip surface) before the mold compound is applied. This preliminary treatment ensures that when the mold is subsequently applied, optimal adhesion is achieved without requiring complex real-time adjustments during the molding process itself.
Solution Approach 2:
The adhesion promoter is selectively applied only to specific surfaces where adhesion is critical (the second frame surface of the lead frame and/or the second chip surface of the semiconductor chip that contact the mold), rather than treating all surfaces uniformly. This localized approach enhances adhesion where needed while minimizing unnecessary process steps and material usage.
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 solution effectively improves adhesion and moisture resistance, enhancing the reliability and longevity of SiC power devices by optimizing the adhesion between the mold compound and various material interfaces, thereby enabling their use in high voltage applications like traction inverter circuits and switch mode power supplies.
Implementation Method 1
The at least one adhesion promoter is on the uncovered surface part of the second frame surface of the lead frame and/or on the second chip surface of the semiconductor chip. Each of the at least one adhesion promoter is optimized to enhance adhesion between the mold, and either the second frame surface of the lead frame or the second chip surface of the semiconductor chip.
Data Source
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AI summary
The present disclosure relates to a semiconductor device. It is comprised of a lead frame, a semiconductor chip, a mold, and at least one adhesion promoter, wherein the lead frame comprises a first frame surface and a second frame surface opposite the first frame surface, and wherein the semiconductor chip comprises a first chip surface and a second chip surface opposite the first chip surface, wherein the first frame surface of the lead frame is an outer surface of the semiconductor device, with the second frame surface of the lead frame attached to the first chip surface of the semiconductor chip such, that the second frame surface of the lead frame is partially covered by the first chip surface of the semiconductor chip, wherein an uncovered surface part of the second frame surface of the lead frame and the second chip side of the semiconductor chip are in direct or indirect contact with the mold by means of the adhesion promoter, wherein the at least one adhesion promoter is on the uncovered surface part of the second frame surface of the lead frame and/or on the second chip surface of the semiconductor chip, wherein each of the adhesion promoter is optimized to enhance adhesion between the mold, and either the second frame surface of the lead frame or the second chip surface of the semiconductor chip.