LDMOS Source-Body Contact Layout With Self-Aligned Spacer Doping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing fabrication processes for LDMOS devices are complex and require multiple photomasks, leading to increased complexity and potential errors, while also affecting the lateral size and resistance characteristics of the source and body contact regions, which impact the device's performance.
Innovation Solution
A method is introduced that reduces the number of photomasks needed by using self-aligned processes for forming the source and body contact regions, with a spacer layer aiding in the ion implantation and etching steps to define these regions, thereby simplifying the fabrication and controlling the lateral dimensions and doping densities for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photomasks are used in the fabrication process, then the source and body contact regions can be formed with precise lateral dimensions, but the fabrication process complexity increases
Solution Approach 1:
The spacer structure serves as a self-aligned mask that automatically defines the lateral boundaries of the source and body contact regions. The spacer's width, controlled by conformal deposition thickness, directly determines the contact region dimensions without requiring separate photomask alignment steps. This self-service mechanism eliminates multiple photomasks while maintaining precision.
Solution Approach 2:
The spacer acts as an intermediary structure between the gate electrode and the contact regions. By depositing the spacer conformally over the gate and isolation structures, the patent creates a intermediate layer that automatically positions and sizes the contact regions through its lateral extent, simplifying the overall fabrication sequence.
2Device complexity
If the number of photomasks is reduced, then the fabrication process is simplified, but the control over lateral dimensions and doping densities may be affected
Solution Approach 1:
The patent controls the lateral dimensions of contact regions by adjusting the spacer deposition parameters (thickness, conformality) and the etch parameters. By changing these process parameters, precise control over the contact region geometry is achieved without requiring multiple photomasks, maintaining manufacturing precision while simplifying the process.
3Device complexity
If self-aligned processes are used with spacer layers, then the fabrication process is simplified, but additional deposition and etching steps are required
Solution Approach 1:
The patent merges the functions of multiple photomasks into a single spacer-based self-aligned process. The spacer simultaneously serves as a mask for defining both the source and body contact regions, combining what would otherwise require separate masking steps into one integrated process sequence, thereby reducing overall complexity despite adding deposition and etch steps.
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 reduces the complexity of the fabrication process, allows for precise control of the source and body contact regions' dimensions, and enhances the device's performance by minimizing base resistance and Kirk effect, leading to improved operational characteristics.
Implementation Method 1
implanting first-type dopants into an exposed portion of the second semiconductor region masked by a hard mask to form a source precursor region
Implementation Method 2
recessing a surface region in the source precursor region by an etching process masked at least by the spacer
Data Source
AI summary
A method of manufacturing a semiconductor device includes forming a gate electrode overlying a gate dielectric layer covering both a channel region in a second semiconductor region and a portion of a first semiconductor region. First-type dopants are implemented into the second semiconductor region masked by a hard mask to form a source precursor region. The method also includes forming a spacer which overlies the source precursor region and has a first side laterally adjacent to the gate electrode, and recessing a surface region in the source precursor region masked by the spacer to form a source region. The method still includes implanting second-type dopants through the surface region masked at least by the spacer to form a body contact region, and forming a conformal conductive layer covering an upper surface of the body contact region and a side surface of the source.