Power Device Resistance Simulation via N-Finger Equivalent Model
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Solution Overview
Problem
Current simulation methods for parasitic resistance in power devices are inaccurate, especially when the channel on-resistance is small, leading to deviations in the final product's performance and inability to meet design demands.
Innovation Solution
A simulation method and tool that establish an equivalent resistance model for power devices with N finger structures, using a parallel connection of resistors to calculate the total resistance and subsequently derive the parasitic resistance by subtracting the channel resistance, improving accuracy by considering the connection relationship of metal layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If experience-based estimation or LPE tool extraction is used to obtain parasitic parameters, then the simulation process is simple and fast, but the accuracy of parasitic resistance values is low, causing large deviations in simulation results
Solution Approach 1:
The patent segments the power device into N finger structures, each with its own channel resistance, source resistance, and drain resistance. By dividing the device into discrete segments, the model can accurately calculate parasitic resistance for each finger while maintaining overall simulation accuracy. This segmentation approach transforms a complex device into manageable units that can be systematically analyzed.
Solution Approach 2:
The patent introduces specific parameter definitions for channel resistance (RDEV), source resistance (RS), and drain resistance (RD) for each finger structure. By changing from generic parasitic resistance estimation to specific parameter-based calculation, the model achieves higher accuracy. The resistance of each finger is calculated as Rb = RDEV/N + RS + RD, where N is the number of fingers, allowing precise control over resistance parameters.
2Reliability
If the channel on-resistance is small, then the device performance is improved, but the parasitic resistance contributes more significantly to the total resistance, making simulation accuracy more critical
Solution Approach 1:
The patent introduces an intermediate metal layer with specific resistance (RS) as a mediator between the source region and the source metal strip. This intermediate layer accounts for the parasitic resistance contribution that becomes significant when channel resistance is small. By explicitly modeling this intermediate layer, the simulation accurately captures the parasitic effects that would otherwise be negligible in high-resistance devices but become dominant in low-resistance devices.
3Measurement precision
If a detailed equivalent resistance model considering finger connection relationships is established, then the simulation accuracy is improved, but the calculation complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-calculating the equivalent resistance of the finger connection network using the derived formula. Instead of performing complex numerical simulations during the design process, the model provides a closed-form solution that can be quickly computed. The equivalent resistance is calculated as Req = (RDEV/N + RS + RD) || Ra || Rc, where the parallel connections are systematically resolved, saving significant computation time while maintaining accuracy.
Data Source
AI summary
The present application relates to a resistance simulation method for a power device, comprising: establishing an equivalent resistance model of a power device, wherein the connection relationship of N fingers is equivalent to N resistors Rb connected in parallel, input ends of adjacent resistors Rb are connected by means of a resistor Ra, output ends of adjacent resistors Rb are connected by means of a resistor Rc,Ra=1NR0,Rc=1NR1,and Rb=RDEV*N+RS+RD, wherein R0 and R1 are respectively resistances of a source metal strip and a drain metal strip, Rs is a metal resistor of a first intermediate layer connecting one source region to the source metal strip, RD is a metal resistor of a second intermediate layer connecting one drain region to the drain metal strip, and RDEV is the channel resistance of the power device; and calculating the resistance of the equivalent resistance model as the resistance of the power device.