HVPMOS Transistor Composite Drift Region for On-Resistance and Breakdown Voltage
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Solution Overview
Problem
The existing BCD process for manufacturing HVPMOS transistors faces challenges in controlling the implantation dosage of P-type dopants, leading to limitations in breakdown voltage and on resistance, where high dosage decreases breakdown voltage and low dosage increases on resistance.
Innovation Solution
The method involves implanting N-type dopants to form a deep N-type well and then implanting P-type dopants of varying concentrations along a horizontal direction to create a composite drift region with increasing doping concentration and junction depth, allowing for more precise control and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high dosage of P-type dopants is implanted to reduce on resistance, then on resistance decreases, but breakdown voltage decreases
Solution Approach 1:
The patent applies local quality by creating a composite drift region with spatially varying doping concentrations. Multiple P-type dopant implants with different concentrations are performed at different locations within the drift region, allowing each local area to have optimized electrical properties. This resolves the contradiction by enabling low on-resistance in high-current regions while maintaining high breakdown voltage in regions requiring voltage blocking capability.
Solution Approach 2:
The patent changes the doping concentration parameter across the drift region by implementing multiple P-type dopant implants with varying doses. The first implant uses a lower concentration while subsequent implants use progressively higher concentrations at different locations. This parameter variation allows simultaneous optimization of both on-resistance and breakdown voltage, resolving the trade-off between these two critical parameters.
2Reliability
If low dosage of P-type dopants is implanted to maintain breakdown voltage, then breakdown voltage is maintained, but on resistance increases
Solution Approach 1:
The patent merges multiple P-type dopant implantation steps into a composite drift region structure. By combining implants with different concentrations and locations, the solution achieves both high breakdown voltage (from lower concentration implants) and low on-resistance (from higher concentration implants), resolving the contradiction through synergistic combination of multiple doping profiles.
Solution Approach 2:
The patent transitions from a uniform one-dimensional doping profile to a multi-dimensional composite doping structure. Multiple dopant implants create a two-dimensional or three-dimensional distribution of doping concentrations within the drift region, allowing independent optimization of electrical properties in different spatial dimensions. This resolves the contradiction by decoupling the relationship between on-resistance and breakdown voltage through spatial dimensionality.
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 enhances the intrinsic breakdown performance and reduces on resistance of the HVPMOS transistor, achieving better power handling capabilities and lower power losses.
Implementation Method 1
implanting N-type dopants in the P-type substrate; dispersing the implanted N-type dopants in the P-type substrate to form a deep N-type well
Implementation Method 2
implanting P-type dopants of different doping concentrations in the deep N-type well along a horizontal direction of the deep N-type well; dispersing the implanted P-type dopants to form a composite drift region
Data Source
AI summary
In one embodiment, method of making a high voltage PMOS (HVPMOS) transistor, can include: (i) providing a P-type substrate; (ii) implanting N-type dopants in the P-type substrate; (iii) dispersing the implanted N-type dopants in the P-type substrate to form a deep N-type well; (iv) implanting P-type dopants of different doping concentrations in the deep N-type well along a horizontal direction of the deep N-type well; and (v) dispersing the implanted P-type dopants to form a composite drift region having an increasing doping concentration and an increasing junction depth along the horizontal direction of the deep N-type well.