Semiconductor Chip Bonding Paste Layout for Corner Wetting Control
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Solution Overview
Problem
In semiconductor device manufacturing, existing bonding techniques face challenges in ensuring adequate spread of bonding material to the corners of semiconductor chips and controlling sintered density, leading to poor wetting and increased leakage current during Temperature Humidity Bias tests, which reduces the reliability of the devices.
Innovation Solution
A method involving the use of a paste-like bonding material with a central portion, extended portions to the corners, and retreated portions from the sides, where the bonding material is pressed and spread to cover the entire surface of the chip, ensuring a distance of 40 μm or more between the chip surface and the bonding material's crept-up edge, and controlling the density by varying the void ratios in different portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is supplied to the substrate and pressed down with the semiconductor chip, then the solder spreads over the bottom surface of the chip, but the solder does not spread to the corners of the chip resulting in poor solder wetting
Solution Approach 1:
The bonding material is divided into multiple portions: a central portion located at the center of the chip, extended portions extending toward each vertex of the chip, and retreated portions retreated from each side of the chip. This segmentation ensures that the bonding material reaches all corners while maintaining appropriate density distribution.
Solution Approach 2:
Different portions of the bonding material have different void ratios (density characteristics). The extended portions have lower void ratios to ensure good corner coverage, while the central portion has higher void ratio for optimal bonding strength. This local quality variation resolves the contradiction between corner coverage and overall bonding quality.
2Reliability
If a paste-like sintered material is used as bonding material and pressed down with the semiconductor chip, then the material creeps up along the side surfaces of the chip, but this increases leakage current during THB tests reducing reliability
Solution Approach 1:
The bonding material is designed with retreated portions that are pulled back from the sides of the chip before bonding. This preliminary configuration prevents the material from creeping up too high along the side surfaces during the bonding process, thereby preventing leakage current issues while still ensuring adequate bonding strength through the central and extended portions.
3Quantity of substance
If the bonding material is supplied in the same form as the semiconductor chip, then the material covers the chip area, but the corners of the chip do not receive adequate bonding material
Solution Approach 1:
The bonding material pattern is segmented into extended portions that specifically target the corner regions of the chip. These extended portions protrude beyond the main body of the bonding material to ensure that corners receive adequate material coverage, while the retreated portions prevent excessive material at the sides.
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 approach effectively improves the reliability of semiconductor devices by ensuring proper bonding material spread to corners, reducing leakage current, and preventing electromigration, while maintaining high density for efficient heat dissipation and crack suppression.
Implementation Method 1
pressing down the bonding material with the object to be bonded
Implementation Method 2
the bonding material that has crept up along a side surface of the object to be bonded
Implementation Method 3
the semiconductor chip is bonded to the substrate by applying pressure and heating
Data Source
AI summary
A manufacturing method of a semiconductor device includes the steps of supplying a paste-like bonding material on a base material, pressing down the bonding material with an object to be bonded, and bonding the object to be bonded onto the base material by the bonding material. The object to be bonded is rectangular. The bonding material supplied onto the base material includes a central portion located at a center of the object to be bonded, an extended portion extending from the central portion toward each vertex of the object to be bonded, and a retreated portion that is retreated from each side of the object to be bonded. A distance of 40 μm or more is secured from an upper surface of the object to be bonded to an upper end of the bonding material that has crept up along a side surface of the object to be bonded.