LDMOS Self-Aligned Channel via Field Oxide Spacer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional LDMOS devices face performance limitations due to deviations in channel length, leading to high on-resistance and low cutoff frequency, caused by inaccuracies in positioning and doping regions during the manufacturing process.
Innovation Solution
A semiconductor structure and manufacturing method involving a self-aligned process with specific doping regions and gate structures, where the field oxide film and pattern layers are used to determine precise positions and sizes of doping regions and gate structures, ensuring a consistent channel length and reduced on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing processes are used for LDMOS devices, then the manufacturing process is simple, but the channel length positioning accuracy is poor leading to high on-resistance and low cutoff frequency
Solution Approach 1:
The field oxide film spacer serves as a self-aligned mask that automatically defines the precise position and width of the second doping region and gate structure. The spacer's width, determined by the field oxide film thickness, directly determines the channel length without requiring additional alignment steps, making the process self-correcting and highly precise
Solution Approach 2:
The field oxide film is formed and etched to create spacers before the doping and gate formation steps. This preliminary structuring establishes the exact channel length definition early in the process, ensuring that subsequent doping regions and gate structures are automatically positioned with high precision relative to each other
2Reliability
If the channel length is increased to reduce on-resistance, then the on-resistance decreases, but the cutoff frequency decreases
Solution Approach 1:
The invention precisely controls the channel length parameter through the field oxide film spacer thickness, enabling optimization of the trade-off between on-resistance and cutoff frequency. By adjusting the spacer thickness, the channel length can be precisely tuned to achieve the optimal balance between these two performance parameters
3Manufacturing precision
If multiple alignment steps are used to position doping regions and gate structures, then the positioning accuracy improves, but the manufacturing process complexity and time increase
Solution Approach 1:
The field oxide film spacer automatically serves as the alignment reference for both the second doping region and the gate structure. This self-aligned approach eliminates the need for multiple photolithography alignment steps, reducing both process complexity and manufacturing time while maintaining high positioning accuracy
Solution Approach 2:
The invention merges the functions of multiple alignment references into a single field oxide film spacer structure. This spacer simultaneously defines the position for doping and gate formation, consolidating what would otherwise require separate alignment steps into one unified process
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 method achieves a small channel length, reduced on-resistance, and increased cutoff frequency by accurately determining the positions and sizes of doping and gate structures, thereby enhancing the performance of LDMOS devices.
Implementation Method 1
the field oxide film is etched with the first pattern layer as a mask using a dry etching process
Implementation Method 2
forming a second doping region in the first doping region with the first pattern layer and the field oxide film as a mask, wherein the second doping region is doped with second doping ions
Data Source
AI summary
A method for manufacturing the semiconductor structure, including: providing a substrate including a first doping region, wherein a field oxide film is disposed on a top surface of the first doping region, a first pattern layer is disposed on a top surface of the field oxide film, and the first pattern layer exposes a portion of the top surface of the field oxide film; etching the field oxide film with the first pattern layer as a mask until a top surface of the substrate is exposed; forming a second doping region in the first doping region with the first pattern layer and the field oxide film as a mask; and forming a plurality of gate structures on a portion of a top surface of the second doping region, a spacer of the field oxide film and a portion of the top surface of the field oxide film.