Ring-Shaped Gate DMOS Corner Threshold Control
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Solution Overview
Problem
Conventional DMOS devices with ring-shaped gates experience reduced threshold voltage due to lower resistance at the corners of the ring-shaped structure, leading to deteriorated performance as they turn ON at lower gate voltages.
Innovation Solution
The DMOS device design includes a ring-shaped gate structure where the corners are either completely or partially located on the isolation structure, and the lightly doped drain is positioned apart from the corners by a predetermined distance, ensuring that the body region and source are doped with appropriate impurities to maintain higher resistance and threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the gate has a ring-shaped structure, then the device can be manufactured with standard processes, but the resistance around the corners is relatively lower causing the device to turn ON at lower gate voltage
Solution Approach 1:
The patent applies local quality by positioning the lightly doped drain at different distances from different parts of the ring-shaped gate. Specifically, the lightly doped drain is positioned closer to the middle sections of the gate than to the corner sections, creating non-uniform doping distribution that compensates for the corner effect and maintains consistent threshold voltage across the device.
2Ease of manufacture
If the body region has lower impurity concentration at the corners, then the device can be formed with standard doping processes, but the resistance is reduced and threshold voltage decreases
Solution Approach 1:
The patent applies preliminary action by pre-positioning the lightly doped drain at optimized locations before final device operation. The lightly doped drain is placed at specific distances from the ring-shaped gate structure during manufacturing, creating a predetermined doping profile that will compensate for corner effects during device operation, thereby ensuring consistent threshold voltage without requiring complex post-manufacturing adjustments.
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 design enhances the performance of DMOS devices by maintaining a higher threshold voltage and reducing leakage currents, thereby improving the operational characteristics of the device.
Implementation Method 1
The isolation structure 12 for example is formed by local oxidation of silicon (LOCOS)
Implementation Method 2
a body region doped with first conductive type impurities, which is formed in the first device region
Data Source
AI summary
The present invention discloses a double diffused metal oxide semiconductor (DMOS) device and a manufacturing method thereof. The DMOS device includes: an isolation structure for defining device regions; a gate with a ring-shaped structure; a drain located outside the ring; and a lightly doped drain, a source, and a body electrode located inside the ring. To increase the sub-threshold voltage at the corners of the gate, the corners are located completely on the isolation structure, or the lightly doped drain is apart from the corners by a predetermined distance.