Adjustable Threshold Voltage High Voltage Depletion Mode MOS Device
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Solution Overview
Problem
Existing high voltage MOS devices require extra masks and process steps to achieve different threshold voltages, increasing manufacturing costs and complexity.
Innovation Solution
A high voltage depletion mode MOS device with an adjustable threshold voltage is formed in a single substrate using a well region, channel region, connection region, gate, lightly doped diffusion region, source region, and drain region, where the doping concentration of the gate is determined to achieve different threshold voltages without additional masks or process steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If extra masks and process steps are used to form dielectric layers with different thickness or well regions with different doping concentrations, then high voltage MOS devices of different threshold voltages can be formed, but manufacturing cost increases
Solution Approach 1:
The patent adjusts the threshold voltage by changing the doping concentration parameter of the well region. By implanting dopants at different concentrations into different well regions, devices with different threshold voltages are achieved without requiring additional masks or process steps, thus resolving the contradiction between adaptability and ease of manufacture
Solution Approach 2:
The patent applies local quality by creating well regions with different doping concentrations in specific locations on the substrate. Each well region is doped according to the required threshold voltage for that particular device, allowing threshold voltage adjustment without affecting other devices or requiring complex global process changes
2Adaptability or versatility
If extra masks and process steps are used to define dielectric layers with different thickness, then MOS devices with different threshold voltages can be manufactured, but device complexity increases
Solution Approach 1:
The patent simplifies the process by changing only the doping concentration parameter during a single ion implantation process, rather than adding multiple process steps. This maintains device complexity at a low level while still achieving the goal of threshold voltage adjustment across multiple devices
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 allows for the cost-effective production of high voltage MOS devices with varying threshold voltages on a single substrate, enhancing design flexibility and reducing manufacturing complexity.
Implementation Method 1
a gate with the first conductive type, which is formed on the top surface, wherein in the vertical direction, the gate is stacked on and contacts the top surface, and is located above and contacts at least a portion of the channel region, wherein the gate is configured to operably control the channel region to be depleted or not depleted
Implementation Method 2
the gate includes impurities with the first conductive type or impurities with both the first conductive type and the second conductive type, and a net doping concentration of the gate is determined according to a target threshold voltage
Data Source
AI summary
A high voltage depletion mode MOS device with adjustable threshold voltage includes: a first conductive type well region; a second conductive type channel region, wherein when the channel region is not depleted, the MOS device is conductive, and when the channel region is depleted, the MOS device is non-conductive; a second conductive type connection region which contacts the channel region; a first conductive type gate, for controlling the conductive condition of the MOS device; a second conductive type lightly doped diffusion region formed under a spacer layer of the gate and contacting the channel region; a second type source region; and a second type drain region contacting the connection region but not contacting the gate; wherein the gate has a first conductive type doping or both a first and a second conductive type doping, and wherein a net doping concentration of the gate is determined by a threshold voltage target.