Multi-Field-Plate LDMOS Structure for Mask-Free Oxide Thickness Control
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Solution Overview
Problem
Manufacturing high-voltage LDMOS transistors with optimized oxide layer thickness under field plates is challenging due to the need for additional masks, increasing manufacturing costs and complexity.
Innovation Solution
A method for simultaneously forming first and second gate oxides on a semiconductor substrate, with field plates and barrier layers, allowing for optimized oxide layer thickness distribution between the gate and drain without requiring additional masks, thereby simplifying the manufacturing process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional masks are used to manufacture oxide layers with different thicknesses under field plates, then the oxide layer thickness can be optimized for breakdown voltage, but the manufacturing cost increases
Solution Approach 1:
The patent combines multiple oxide layer formation operations into a single simultaneous deposition process. Multiple field plates with different required oxide thicknesses are formed in one step by controlling the deposition process, eliminating the need for separate masking and deposition steps for each field plate, thus reducing manufacturing cost while maintaining optimized breakdown voltage characteristics
Solution Approach 2:
The patent implements local quality by creating different oxide thicknesses at different locations under various field plates within the same device structure. This is achieved through selective deposition techniques that deposit varying amounts of oxide material at different positions, allowing each field plate region to have the optimal oxide thickness for its specific electrical requirements
2Reliability
If additional masks are used to manufacture oxide layers with different thicknesses, then the electric field distribution can be optimized, but the device complexity increases
Solution Approach 1:
The patent merges multiple oxide formation processes into a single simultaneous deposition step. By using a unified process that can deposit varying oxide thicknesses across different field plate regions in one operation, the manufacturing process complexity is reduced while still achieving the desired electric field distribution optimization under each field plate
Solution Approach 2:
The patent employs parameter changes during the oxide deposition process to achieve different thicknesses. By modifying deposition parameters such as deposition time, rate, or local deposition conditions during a single process step, the system can create the required thickness variations without adding process steps, thereby simplifying the overall manufacturing complexity
Data Source
AI summary
An LDMOS having multiple field plates and manufacturing method. The LDMOS has a semiconductor substrate with an upper surface, an interlayer dielectric layer with an upper surface, a gate conducting layer, a field plate barrier layer, a first field plate and a second field plate. The gate conducting layer has a plate portion and a channel portion. The field plate barrier layer disposes in the interlayer dielectric layer between the plate portion and the drain. The first field plate disposes in the interlayer dielectric layer and extends from the field plate barrier layer through the interlayer dielectric layer to the upper surface of the interlayer dielectric layer. The second field plate disposes in the interlayer dielectric layer and extends from the field plate barrier layer through the interlayer dielectric layer to the upper surface of the interlayer dielectric layer.