Semiconductor Device Trench Impurity Gradient
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Solution Overview
Problem
Existing semiconductor device manufacturing methods face challenges in achieving stable breakdown voltage due to variations in impurity concentration, which can lead to element breakage and manufacturing process susceptibility.
Innovation Solution
A semiconductor device with a superjunction structure featuring a p-type region with high and low concentration regions along the inner wall of a hole portion, where the width of the high-concentration region decreases from the front surface to the deeper position, and ion implantation angles are adjusted to control the impurity concentration distribution, reducing the need for precise trench shape control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform impurity concentration distribution is used in the trench, then a uniform electric field intensity distribution is achieved and high breakdown voltage is obtained, but small variations in impurity amounts significantly reduce the breakdown voltage and cause element breakage
Solution Approach 1:
The patent applies local quality by creating a non-uniform impurity concentration distribution within the trench structure. Specifically, the impurity concentration is made higher near the trench opening and lower toward the deeper regions, forming localized concentration gradients. This local variation in impurity quality allows the electric field distribution to be optimized for reliability while reducing sensitivity to manufacturing variations.
2Reliability
If the impurity concentration distribution is made inclined in the depth direction to prevent element breakage, then reliability is improved, but precise control of trench shape (width and inclination angle) is required, making the process susceptible to manufacturing variations
Solution Approach 1:
The patent employs parameter changes by systematically varying the impurity concentration as a function of depth position within the trench. The concentration parameter is changed from uniform to graded, with specific relationships defined between concentration and depth. This parameter transformation achieves the desired reliability improvement while avoiding the need for complex trench geometry control.
3Manufacturing precision
If precise control of trench shape (opening width and side surface inclination) is implemented to control impurity amount, then manufacturing precision is improved, but the process becomes more susceptible to variations and complexity increases
Solution Approach 1:
The patent applies inversion by reversing the conventional approach: instead of controlling trench geometry (shape and angles) to achieve desired impurity distribution, the method directly controls impurity concentration as the primary parameter. This inverted approach makes the process more robust by eliminating the need for precise geometric control and reducing sensitivity to manufacturing variations in trench dimensions.
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 stabilizes device characteristics by maintaining high breakdown voltage despite manufacturing variations and allows for less precise control over trench shapes, enhancing manufacturing reliability.
Implementation Method 1
a first impurity region of a first conductive type is formed in the semiconductor substrate by ion implantation
Data Source
AI summary
Provided are a semiconductor device and a manufacturing method therefor that can prevent the breakage of an element and in which the control of impurity amounts is less susceptible to variations in manufacturing processes. A semiconductor substrate has a front surface and includes hole portions extending from the front surface to an inside of the substrate. N-type regions are formed in the semiconductor substrate. At wall surfaces of the hole portions, p-type regions are formed to configure p-n junction with the n-type regions. Each of the p-type regions includes a low-concentration region and a high-concentration region formed at the wall surface of each hole portion. A width of the high-concentration region along the wall surface of the hole portion becomes smaller from the front surface toward a deeper position.