Selective Ion Implantation via Resist Shadowing
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Solution Overview
Problem
Conventional semiconductor manufacturing processes for forming devices with different threshold voltages are time-consuming and prone to defects, as they require multiple steps and mask changes for precise ion implantation, leading to inefficiencies in productivity and yield.
Innovation Solution
A method that utilizes the shadowing effect of the resist layer by adjusting the tilt and twist angles of the ion implantation process to selectively implant ions into specific regions, reducing the number of process steps and enabling simultaneous formation of devices with different threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photolithography and ion implantation processes are performed individually for each device to form pocket implant areas, then precise control of threshold voltage for different devices is achieved, but the manufacturing process becomes time-consuming and productivity decreases
Solution Approach 1:
The patent merges multiple separate photolithography and ion implantation processes into a single integrated process. By forming a unified mask pattern that defines implant areas for multiple devices with different threshold voltages simultaneously, and performing one ion implantation process that implants different ion species into different regions based on the mask pattern, the method achieves precise threshold voltage control for multiple devices while significantly improving manufacturing efficiency and reducing process time
Solution Approach 2:
The mask pattern and ion implantation process are designed to serve multiple functions simultaneously. The single mask pattern defines implant areas for multiple devices with different threshold voltage requirements, and the ion implantation process delivers different ion species (e.g., boron for N-channel, phosphorus for P-channel) to different regions through selective masking, enabling universal application across various device types without requiring separate processes
2Manufacturing precision
If traditional angled ion implantation is used to form pocket implant areas, then dopant can be implanted into the desired area adjacent to gate edge, but shadowing from resist layer sidewalls causes undesirable deviations in electrical characteristics
Solution Approach 1:
The patent transitions from traditional angled ion implantation to normal-incidence ion implantation, changing the dimensional approach from oblique to perpendicular. This dimensional change eliminates the shadowing effect caused by resist layer sidewalls, allowing dopants to be implanted precisely into the intended pocket implant areas adjacent to gate edges without deviation, thereby improving both placement accuracy and electrical characteristic consistency
Solution Approach 2:
The mask pattern is designed with openings that precisely define the implant areas, creating a template that guides the ion implantation process. The mask copies the desired implant geometry onto the substrate, ensuring that dopants are deposited only in the intended regions with accurate spatial distribution, achieving precise dopant placement without shadowing artifacts
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 enhances time and cost efficiency by reducing the number of process steps and minimizing defects, allowing for the formation of devices with precise doping concentrations and improved electrical characteristics.
Implementation Method 1
This invention provides a method to form different devices by utilizing the shadowing effect of the resist layer, enabling the selective implantation or blocking of ions into certain regions.
Implementation Method 2
an ion implantation process including a partial shadowing ion implant is performed, wherein the second implant area is implanted by the partial shadowing ion implant to a predetermined concentration
Data Source
AI summary
A method of forming semiconductor devices. First, a substrate is provided, and a first implant area and a second implant area are defined in a mask pattern. Subsequently, a resist layer on the substrate is patterned using the mask pattern to form a first opening exposing the first implant area and a second opening to expose the second implant area. After that, an ion implantation process including a partial shadowing ion implant is processed, wherein the second implant area is implanted by the partial shadowing ion implant to a predetermined concentration, and the first implant area is substantially not implanted by the partial shadowing ion implant.