Temperature Sense Diode Segmentation for IGBT Thermal Monitoring
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Solution Overview
Problem
The existing methods for manufacturing PIN diodes in power modules, such as those used in IGBTs, face challenges in achieving high-accuracy temperature dependency and high-speed response while maintaining a compact size, as variations in film thickness, ion implantation, and heat treatment conditions affect the diode characteristics, leading to increased apparatus size and characteristic variations.
Innovation Solution
A method involving the formation of a PIN diode on a semiconductor substrate, followed by selective oxidation or sublimation to divide the diode into multiple smaller diodes, which are connected in parallel or series, reducing the overall device size and minimizing characteristic variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the area of the diode is increased to reduce variations in ion implantation and finished dimension, then the manufacturing precision is improved, but the area of the entire apparatus increases
Solution Approach 1:
The patent divides a single large-area PIN diode into multiple smaller PIN diodes by forming partition walls between them. This segmentation allows each small diode to maintain consistent characteristics while the collective array provides sufficient area for reduced variation. The partition walls are formed by selective oxidation or sublimation of silicon nitride films, creating physical separations that define individual diode regions without requiring a large overall area.
2Reliability
If the IGBT is formed with heat treatment, then the transistor performance is improved, but the characteristics of the PIN diode vary
Solution Approach 1:
The patent extracts the PIN diodes from the heat treatment process by forming them after the IGBT heat treatment is complete. The diodes are formed as separate structures on the semiconductor substrate after the main transistor fabrication, allowing the IGBT to receive necessary heat treatment without exposing the diodes to temperatures that would alter their characteristics. This sequential formation process isolates the diodes from harmful thermal effects.
Solution Approach 2:
The patent performs preliminary heat treatment for the IGBT before forming the PIN diodes. By completing the transistor heat treatment process first, the substrate is prepared for diode formation without subsequent high-temperature steps that would affect diode characteristics. This ordering of operations ensures diode stability while maintaining transistor performance.
3Manufacturing precision
If multiple process parameters are controlled to improve diode characteristics, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The patent performs preliminary formation of the PIN diodes on the semiconductor substrate before forming the IGBT. This preliminary action establishes the diode structures early in the process sequence, allowing subsequent IGBT fabrication steps to proceed without additional diode-related complexity. The diodes are formed using standard semiconductor processes that are already part of the fabrication sequence.
Solution Approach 2:
The patent combines the formation of partition walls and diode separation into a single selective oxidation or sublimation step. Rather than requiring separate processes for creating partition structures and defining diode regions, the selective modification of silicon nitride films accomplishes both functions simultaneously, reducing overall process complexity while maintaining precise diode characteristics.
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 allows for a reduced device size with minimized characteristic variations, enhancing the temperature sense diode's accuracy and response speed, while maintaining high-accuracy temperature assurance and high-speed operation.
Implementation Method 1
an oxide film 25 is formed so as to cover the temperature sense diode 17... part of the temperature sense diode 17 is selectively oxidized
Implementation Method 2
selectively sublimating part of the PIN diode to divide the PIN diode into a plurality of diodes
Data Source
AI summary
An IGBT (15) is formed in a semiconductor substrate (1). A temperature sense diode (17) made of polysilicon or amorphous silicon is formed on the semiconductor substrate (1). After forming the IGBT (15), the temperature sense diode (17) is divided into a plurality of diodes by selectively oxidizing or sublimating part of the temperature sense diode (17). Thus, influences of variations in finished dimension of polysilicon on the characteristics can be eliminated. As a result, it is possible to reduce the size while reducing characteristic variations.