LDMOS Device Segmented Drift Region for Breakdown Voltage
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Solution Overview
Problem
Manufacturing high-performance LDMOS devices without compromising Breakdown Voltage (BV) is challenging, as it requires balancing drain-source Breakdown Voltage (BVds) and drain-source On-Resistance (Rdson).
Innovation Solution
The LDMOS device and manufacturing method involve forming a drift region with second conductivity type regions that extend into a first region, with specific doping concentrations and distances, and include a well region and groove isolations to enhance the depletion region width, thereby reducing electric field density and increasing BVds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional LDMOS device is manufactured with separate N-type drain drift region and P-type well region, then the device structure is simple, but the drain-source Breakdown Voltage (BVds) cannot be increased without compromising device performance
Solution Approach 1:
The drift region is segmented into multiple regions with different conductivity types (first conductivity type and second conductivity type) arranged in an interleaved pattern. This segmentation creates multiple depletion regions that collectively increase the breakdown voltage while maintaining a relatively simple overall device structure.
Solution Approach 2:
Different regions within the drift region are assigned different conductivity types (first conductivity type for well regions, second conductivity type for drift regions) to create localized variations in electrical properties. This local quality differentiation enables enhanced breakdown voltage through controlled electric field distribution.
2Reliability
If the drift region and well region are separated in conventional LDMOS, then the manufacturing process is straightforward, but the electric field density cannot be effectively reduced
Solution Approach 1:
The drift region is divided into multiple alternating regions of first conductivity type (well regions) and second conductivity type (drift regions). This segmentation creates multiple depletion regions that collectively reduce electric field density through distributed field management, while the regions are arranged to be manufacturable with standard doping processes.
Solution Approach 2:
The invention extends the drift region structure into the depth direction with regions extending to different depths, creating a three-dimensional doping profile. This dimensional approach allows for more effective electric field management by distributing the field control throughout the device depth rather than relying solely on planar separation.
3Reliability
If high performance LDMOS device is manufactured, then the device capability is improved, but the drain-source On-Resistance (Rdson) increases
Solution Approach 1:
Different regions are assigned different doping concentrations and conductivity types optimized for their specific functions: well regions with first conductivity type provide field control, while drift regions with second conductivity type provide low-resistance current paths. This local optimization allows high breakdown voltage without excessive on-resistance.
Solution Approach 2:
The invention employs specific doping concentration ranges (2.0×10^12 to 1.0×10^13 atom/cm³ for second regions) and geometric parameters (distance between neighboring second regions of 0.3 μm to 0.7 μm) to optimize the balance between breakdown voltage and on-resistance, achieving high performance with minimal energy loss.
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 increases the drain-source Breakdown Voltage (BVds) while improving performance by maintaining or reducing the drain-source On-Resistance (Rdson), offering higher performance without sacrificing device characteristics.
Implementation Method 1
forming a drift region that has a second conductivity type in the first region... forming a plurality of second regions that have the first conductivity type by conducting a doping process
Implementation Method 2
enhance the depletion region width, thereby reducing electric field density and increasing BVds
Data Source
AI summary
A Lateral Diffusion Metal Oxide Semiconductor (LDMOS) device and its manufacturing method are presented. The LDMOS device comprises a first region that has a first conductivity type; a drift region that has a second conductivity type in the first region, wherein the second conductivity type is opposite to the first conductivity type; and a plurality of second regions that have the first conductivity type in the drift region, wherein the second regions are separated from each other and extend to the first region along a depth direction of the drift region. This LDMOS device has an higher Breakdown Voltage and thus better performance than conventional LDMOS devices.