Semiconductor Device With Dummy Well For Multi-Voltage Integration
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Solution Overview
Problem
The complexity of integrating multiple semiconductor elements with different operating voltages and varying gate insulating layer thicknesses, conductive types, and impurity densities leads to increased processing steps and costs in semiconductor device fabrication.
Innovation Solution
The semiconductor device incorporates first and second transistors with gate insulating layers of different thicknesses, where at least one transistor is formed directly over a dummy well, using a simplified fabrication process that reduces the number of steps and costs by employing photolithography and ion implantation techniques to form wells and gate insulating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple semiconductor elements with different operating voltages and varying gate insulating layer thicknesses are integrated, then device functionality and versatility are improved, but processing steps and fabrication complexity increase
Solution Approach 1:
The substrate is divided into multiple regions with different well depths (first depth and second depth), allowing different transistor types (e.g., NMOS and PMOS) to be formed in separate regions. This segmentation enables each region to be optimized for specific device requirements while using a unified fabrication process, thus improving device functionality without proportionally increasing processing complexity.
Solution Approach 2:
Different regions of the substrate are assigned different local properties: first regions have wells at a first depth with first gate insulating layer thickness, while second regions have wells at a second depth with second gate insulating layer thickness. This local differentiation allows each region to be tailored for specific transistor types and operating characteristics, enhancing device versatility while maintaining process efficiency.
2Reliability
If multiple semiconductor elements with different conductive types and impurity densities are separately fabricated, then device performance is improved, but the number of fabrication steps increases
Solution Approach 1:
The fabrication process merges the formation of different well types (first conductive type and second conductive type) into a single unified process. By forming both first wells and second wells in the same substrate using the same ion implantation and thermal processing steps, the method achieves high device performance for multiple transistor types while avoiding the need for separate fabrication sequences.
Solution Approach 2:
The ion implantation process is designed to be universal, capable of forming both n-type and p-type wells in the same substrate during a single fabrication sequence. The same basic process steps (ion implantation, thermal processing) serve multiple functions: forming different well types, controlling impurity densities, and creating the necessary electrical characteristics for various transistor operations.
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 fabrication of semiconductor devices with reduced processing steps and lower costs, enabling the integration of various types of transistors with different gate insulating layers, such as NMOS and PMOS devices, while maintaining device functionality.
Implementation Method 1
employing photolithography and ion implantation techniques to form wells and gate insulating layers
Data Source
AI summary
Provided are a semiconductor device and a method of fabricating the semiconductor device. The semiconductor device may include first transistors that include a first gate insulating layer having a first thickness and second transistors include a second gate insulating layer having a second thickness less than the first thickness. At least one of the transistors formed on the first or second gate insulating layers may be directly over a dummy well.