Semiconductor Structure Fabrication with Simultaneous Well Formation
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Solution Overview
Problem
The existing semiconductor fabrication process is overly complex and inefficient due to the need for multiple photolithography steps and ion implantation processes to form various well regions and lightly-doped-drain implant regions, leading to increased costs and time.
Innovation Solution
A method where middle-voltage P well and N well regions are formed simultaneously in corresponding active regions, reducing the number of photolithography steps and ion implantation processes, allowing for the formation of NMOS and PMOS transistors with different operating voltages in a simplified and more efficient manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photolithography steps and ion implantation processes are used to form various well regions and lightly-doped-drain implant regions, then the transistor performance can be controlled and optimized, but the fabrication process becomes overly complex and time-consuming
Solution Approach 1:
The patent combines multiple ion implantation processes into a single unified process. Specifically, it forms middle-voltage P well (MVPW) and middle-voltage N well (MVNW) regions simultaneously in one implantation step, and forms NMOS lightly-doped-drain implant for low VDD (NLL) and N-type heavily-doped regions in one step, thereby reducing the number of separate photolithography and implantation steps while maintaining transistor performance control
Solution Approach 2:
The patent creates a multi-functional fabrication approach where a single ion implantation process accomplishes multiple objectives: forming both MVPW and MVNW regions, creating NLL and NLH regions, and establishing different well structures for various transistor types (PMOS and NMOS) with different voltage requirements, thereby reducing overall process complexity
2Manufacturing precision
If multiple photolithography steps are used to define doped wells for different parts of the semiconductor structure, then the doping profile can be precisely controlled, but the fabrication time and cost increase
Solution Approach 1:
The patent merges multiple photolithography steps into fewer steps by designing a unified doping process that defines multiple well regions (MVPW and MVNW) and implant regions (NLL and NLH) simultaneously, reducing the total number of photolithography cycles required while maintaining precise doping profile control through single-step patterning
3Manufacturing precision
If multiple ion implantation processes are used to form different well regions and implant regions, then the doping concentration and distribution can be optimized, but the number of fabrication steps increases
Solution Approach 1:
The patent combines multiple ion implantation processes into unified steps: forming MVPW and MVNW regions in one implantation process, and forming NLL and NLH regions in another single implantation process. This maintains optimized doping concentration and distribution control while reducing the total number of separate fabrication steps, thereby improving overall productivity
Solution Approach 2:
The patent utilizes parameter changes in the ion implantation process, such as adjusting implantation energy and dose, to achieve different doping profiles and concentrations for various regions (MVPW, MVNW, NLL, NLH) within a reduced number of steps, maintaining manufacturing precision while improving fabrication efficiency
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 simplifies the semiconductor structure fabrication, reduces the number of fabrication steps, and improves efficiency and cost-effectiveness by allowing simultaneous formation of well regions and lightly-doped-drain implant regions, resulting in improved reliability and performance of MOS transistors with reduced threshold voltages, higher saturation current, and higher breakdown voltages.
Implementation Method 1
forming a middle-voltage P well (MVPW) region and a middle-voltage N well (MVNW) region in the semiconductor substrate
Implementation Method 2
The formation of the doped wells requires illumination with light of different intensities/types and related photolithography processes for defining doped wells
Data Source
AI summary
The present disclosure provides a method for forming a semiconductor structure. The method includes providing a semiconductor substrate; forming a first active region, a second active region, a third active region, and a fourth active region in the semiconductor substrate; and forming a middle-voltage P well region (MVPW) in each of the first active region and the second region simultaneously and forming a middle-voltage N well (MVNW) region in each of the third active region and the fourth active region simultaneously.