Curved Side Surface Semiconductor Dicing for Reliability
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Solution Overview
Problem
The peeling or cracking of metal layers on the rear surface of power devices during the dicing process leads to electrical failures, chip cracks, and instability in die bonding, affecting the reliability and performance of semiconductor devices.
Innovation Solution
A semiconductor device with a curved side surface is created by using a dicing blade that cuts both the silicon substrate and metal layer, forming a larger lower surface area than the upper surface, which reduces the likelihood of chip chipping and improves die-bonding strength and reduces leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional dicing is used to cut the silicon substrate, then the dicing process can be completed, but the metal layer on the rear surface peels or cracks leading to electrical failures
Solution Approach 1:
The dicing blade is designed with a curved cutting surface instead of a straight blade. This curvature allows the blade to gradually separate the metal layer from the silicon substrate during cutting, preventing sudden peeling or cracking that would cause electrical failures. The curved path distributes the cutting stress more evenly across the material interface.
Solution Approach 2:
The invention changes the geometric parameters of the dicing blade from a conventional straight edge to a curved surface with specific radius of curvature. This parameter change modifies the cutting mechanism to reduce stress concentration at the metal-silicon interface, thereby preventing peeling and cracking while maintaining dicing effectiveness.
2Ease of manufacture
If the metal layer on the rear surface is kept flat, then the manufacturing process is simple, but peeling and cracking occur during dicing and heat cycling
Solution Approach 1:
The metal layer on the rear surface is given a curved profile matching the curvature of the dicing blade. This curvature design prevents stress concentration during cutting and subsequent thermal cycling, eliminating peeling and cracking issues while maintaining manufacturing simplicity through a single curving step before dicing.
3Ease of operation
If a straight dicing blade is used, then the cutting process is straightforward, but chip cracks and fissures form during heat cycle and impact
Solution Approach 1:
The curved dicing blade creates a rounded cut profile in the chip instead of a sharp straight edge. This curvature distributes mechanical stresses during heat cycling and impact, preventing crack initiation and propagation at the cut edges, thereby significantly improving chip strength and reliability.
4Shape
If the upper surface area is larger than the lower surface area, then the device structure is conventional, but die bonding stability is poor
Solution Approach 1:
The curved dicing blade creates a chip shape where the lower surface (cut surface) has a larger effective bonding area than the upper surface. This curvature-induced area difference improves die bonding stability by increasing the contact area between the chip rear surface and the bonding substrate, ensuring more reliable mechanical and electrical connections.
Data Source
AI summary
According to an embodiment, a semiconductor device includes a silicon substrate, a device layer, and a lower layer. The device layer is formed on an upper surface of the silicon substrate. The lower layer is formed on a lower surface of the silicon substrate and has a side surface connecting to a side surface of the silicon substrate. At least a pair of side surfaces of the semiconductor device has a curved shape widening from an upper side toward a lower side.