Semiconductor Device Trench Impurity Control
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Solution Overview
Problem
Existing semiconductor devices require complex design and increased design costs to achieve high breakdown resistance, particularly in the configuration of transistors adjacent to a PN junction diode, where trench depth and impurity concentration must be precisely controlled to improve breakdown resistance.
Innovation Solution
A semiconductor device configuration featuring three or more transistors arranged in a direction with a PN junction diode between them, where the transistors have trenches with different impurity concentrations, with the second trench having a higher impurity concentration than the first, allowing for improved breakdown resistance without the need for precise trench depth control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the trench depth is precisely controlled to improve breakdown resistance, then the breakdown resistance improves, but the design cost increases
Solution Approach 1:
The patent applies local quality by creating different impurity concentration regions at the bottom of trenches adjacent to the PN junction diode. Specifically, a high-concentration n-type impurity region is formed in the drift region at the trench bottom, while other regions maintain lower impurity concentrations. This localized differentiation allows breakdown to occur preferentially in the high-concentration region, improving overall breakdown resistance without requiring complex control of trench depth across all transistors.
Solution Approach 2:
The patent changes the impurity concentration parameter in the drift region at the trench bottom to achieve the desired breakdown characteristics. By increasing the impurity concentration in specific locations (the high-concentration n-type impurity region) rather than uniformly controlling trench depth, the patent achieves improved breakdown resistance with simpler design. The impurity concentration is set to a specific range (1×10^16 to 1×10^18 atoms/cm³) to optimize the breakdown behavior.
2Reliability
If the trench depth is increased to improve breakdown resistance, then the breakdown resistance improves, but the manufacturing precision requirements increase
Solution Approach 1:
Instead of increasing trench depth uniformly across all transistors (which would require high manufacturing precision), the patent applies local quality by forming a high-concentration n-type impurity region specifically at the bottom of trenches adjacent to the PN junction diode. This localized impurity concentration change creates a preferred breakdown path in these specific regions without requiring precise control of trench depth throughout the entire device structure.
Solution Approach 2:
The patent changes the impurity concentration parameter as the primary control mechanism rather than relying on trench depth control. By adjusting the impurity concentration in the drift region at the trench bottom to a specific range, the patent achieves the desired breakdown resistance with relaxed manufacturing precision requirements for trench depth.
3Reliability
If different trench depths are used for transistors adjacent to PN junction diode versus other transistors, then the breakdown resistance improves, but the device complexity increases
Solution Approach 1:
The patent applies local quality by creating a high-concentration n-type impurity region specifically in the drift region at the bottom of trenches adjacent to the PN junction diode. This localized modification creates electrical differentiation that achieves the desired breakdown behavior without requiring physical differentiation through varying trench depths, thereby reducing device structural complexity.
Solution Approach 2:
The patent changes the impurity concentration parameter in specific locations rather than varying trench depth parameters. This approach achieves the same functional effect (preferential breakdown in adjacent transistors) with a simpler device structure, as all trenches can maintain uniform depth while only the impurity concentration varies in specific 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 configuration enables improved breakdown resistance and high withstand voltage with a simpler design, reducing fabrication costs by allowing breakdown to occur in the transistor with higher impurity concentration first, thereby enhancing the breakdown resistance of the semiconductor device.
Implementation Method 1
the breakdown occurs in two transistors adjacent to the PN junction diode earlier than that in two transistors at both ends. For this reason, the breakdown current can flow to the PN junction diode, whereby breakdown resistance can be improved
Data Source
AI summary
A semiconductor device includes: three or more transistors, which are formed on a semiconductor substrate and arranged in one direction; and a PN junction diode, which is formed in a part of a region between the transistors, wherein the transistor includes: a trench, which is formed inwardly from a front surface; and a conductive region in the trench; wherein a first trench is a trench of the transistor which is not adjacent to the PN junction diode, and a second trench is a trench of one or both of the two transistors adjacent to the PN junction diode, wherein a bottom surface of the first trench is formed in a semiconductor region of a first impurity concentration, and wherein a bottom surface of the second trench is formed in a semiconductor region of a second impurity concentration, which is higher than the first impurity concentration.