NLDMOS Device Dual PTOP Layer Breakdown Voltage
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Solution Overview
Problem
Existing NLDMOS devices face limitations in achieving deeper and wider depletion of the drift region and sufficient breakdown voltage, which restricts the enhancement of the device's performance.
Innovation Solution
The NLDMOS device incorporates two PTOP layers with varying energy levels for the PTOP injection, allowing for deeper and wider depletion of the drift region, increasing the area of the depletion region and raising the breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single PTOP layer is formed on the drift region, then the surface field effect is reduced, but the depletion depth and width are insufficient
Solution Approach 1:
The single PTOP layer is segmented into two distinct PTOP layers with different doping concentrations and depths. The first PTOP layer has a doping concentration of 1×10^15 to 1×10^16 atoms/cm³ and extends to a depth of 0.5-2.0 μm, while the second PTOP layer has a doping concentration of 1×10^14 to 1×10^15 atoms/cm³ and extends to a depth of 2.0-5.0 μm. This segmentation allows each layer to contribute differently to the depletion region, achieving both sufficient depletion depth and high breakdown voltage.
Solution Approach 2:
Different regions of the drift region are assigned different PTOP layer characteristics. The first PTOP layer provides stronger depletion near the surface to control the surface field effect, while the second PTOP layer provides extended depletion deeper in the drift region to increase breakdown voltage. This local differentiation of doping profiles optimizes both depletion depth and breakdown characteristics in different spatial zones.
2Length of moving object
If the PTOP layer doping concentration is increased to deepen depletion, then the breakdown voltage increases, but the depletion width decreases
Solution Approach 1:
The doping concentration is segmented across two layers: the first PTOP layer uses higher doping (1×10^15 to 1×10^16 atoms/cm³) to achieve deep depletion, while the second PTOP layer uses lower doping (1×10^14 to 1×10^15 atoms/cm³) to maintain wide depletion. This segmentation resolves the trade-off by distributing the depletion function across layers with optimized individual characteristics.
Solution Approach 2:
The two PTOP layers are designed with asymmetric doping concentrations and depth profiles. The first layer has higher doping and shallower depth, while the second layer has lower doping and greater depth. This asymmetric design allows the system to achieve both deep and wide depletion simultaneously, as each layer contributes its optimal characteristics to the overall depletion region.
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 implementation of two PTOP layers effectively increases the breakdown voltage by 7% from 594 V to 637 V, enhancing the device's performance and efficiency.
Implementation Method 1
a first PTOP layer and a second PTOP layer, formed on the drift region, the first PTOP layer having the same lateral size with the second PTOP layer, the first PTOP layer being spaced from the second PTOP layer in the longitudinal direction and located on the bottom of the second PTOP layer
Data Source
AI summary
An NLDMOS device that includes a drift region, a P well, and a first PTOP layer and a second PTOP layer formed on the drift region, wherein the first PTOP layer has the same lateral size with the second PTOP layer, the first PTOP layer is spaced from the second PTOP layer in the longitudinal direction and located on the bottom of the second PTOP layer, with the depth of the first PTOP layer less than or equal to that of the bottom of the P well. The present invention also discloses a method for manufacturing the NLDMOS device.