SiC Gate Resistor Layout for Parallel Switching Noise Reduction
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Solution Overview
Problem
In modules comprising multiple semiconductor devices connected in parallel, noise occurs due to variations in gate resistance among chips, leading to uneven current distribution and complexity in structure when external gate resistance is used to mitigate this issue.
Innovation Solution
A SiC semiconductor device with a built-in polysilicon resistor between the control pad and control electrode, allowing adjustment of total resistance to dominate over variations in chip resistance, thereby reducing noise and simplifying the module structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple semiconductor devices are connected in parallel with collective gate terminals, then the module can perform simultaneous switching operation, but noise occurs due to variations in gate resistance among chips causing uneven current distribution
Solution Approach 1:
The patent introduces an intermediary resistor (21) made of polysilicon between the control pad (4) and the control electrode (19) to mediate the current flow. This resistor equalizes the current distribution among multiple parallel-connected semiconductor devices by adding a controllable resistance that compensates for variations in gate resistance, thereby reducing noise while maintaining simultaneous switching capability.
Solution Approach 2:
The patent changes the resistance parameter by introducing a polysilicon resistor with a specifically designed resistance value (e.g., 10Ω to 100Ω) that is larger than the variation in gate resistance among chips. This parameter change allows the total resistance (control electrode resistance + polysilicon resistor) to be dominated by the polysilicon resistor, thereby equalizing current distribution and reducing noise.
2Object-affected harmful factors
If external gate resistance is provided to each chip to reduce noise, then the noise and current concentration are mitigated, but the module structure becomes complicated and assembly becomes difficult
Solution Approach 1:
The patent merges the noise-reduction function into the semiconductor device itself by integrating the polysilicon resistor (21) within the device structure, specifically between the control pad and control electrode. This eliminates the need for separate external resistors for each chip, thereby reducing module complexity while maintaining the noise-mitigation function.
Solution Approach 2:
The semiconductor device provides its own noise-reduction function through the built-in polysilicon resistor, making the device self-sufficient. Each chip independently contains the resistor needed to equalize current distribution, eliminating the need for external components and simplifying module assembly.
3Ease of manufacture
If polysilicon is used for the built-in resistor, then the resistance value can be easily controlled and processing is simplified, but the resistor must be integrated within the device structure
Solution Approach 1:
The patent utilizes the property of polysilicon where resistance can be controlled by changing physical parameters such as thickness, width, or length of the resistor layer. By adjusting these parameters during manufacturing, the desired resistance value (e.g., 10Ω to 100Ω) can be achieved, making the built-in resistor easy to manufacture with conventional semiconductor processing techniques.
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
The built-in resistor effectively limits current flow to chips with lower resistance, reducing noise and variations in switching speed while maintaining a simple module structure by using polysilicon, which can be easily processed and controlled.
Implementation Method 1
a built-in resistor (21) disposed below the control pad (4) and made of polysilicon to electrically connect the control pad (4) and the control electrode (19) together
Data Source
AI summary
A semiconductor device (1) is manufactured which includes a SiC epitaxial layer (28), a plurality of transistor cells (18) that are formed in the SiC epitaxial layer (28) and that are subjected to ON/OFF control by a predetermined control voltage, a gate electrode (19) that faces a channel region (32) of the transistor cells (18) in which a channel is formed when the semiconductor device (1) is in an ON state, a gate metal (44) that is exposed at the topmost surface for electrical connection with the outside and that is electrically connected to the gate electrode (19) while being physically separated from the gate electrode (19), and a built-in resistor (21) that is made of polysilicon and that is disposed below the gate metal (44) so as to electrically connect the gate metal (44) and the gate electrode (19) together.