Fin-Type Semiconductor Doping with Protective Film
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Solution Overview
Problem
Conventional semiconductor device fabrication methods using plasma doping fail to provide desired transistor characteristics for fin-type semiconductor devices due to significant impurity loss during the cleaning process, especially on the side surfaces of fin-type semiconductor regions, which affects the on-state current.
Innovation Solution
A method involving plasma doping to implant impurities into the side surfaces of fin-type semiconductor regions, followed by forming a protective film to cover these surfaces before cleaning, reducing impurity loss and maintaining high impurity concentration for low-resistance extension regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If plasma doping is used to implant impurities into fin-type semiconductor regions, then high impurity concentration can be achieved, but significant impurity loss occurs during the subsequent cleaning process
Solution Approach 1:
A protective film is formed on the fin-type semiconductor region before the cleaning process to prevent impurity loss. This preliminary protective action ensures that impurities implanted during plasma doping are retained during subsequent cleaning steps, resolving the contradiction between achieving high impurity concentration and preventing impurity loss.
Solution Approach 2:
The protective film acts as an intermediary layer between the implanted impurities and the cleaning solution. This intermediary protects the impurities from being removed during cleaning while allowing the cleaning process to proceed, thus maintaining high impurity concentration without significant loss.
2Reliability
If shallow extension regions are formed to reduce short channel effect, then transistor characteristics improve, but impurity loss during cleaning significantly reduces the effective impurity concentration
Solution Approach 1:
The protective film is formed before cleaning to preserve the shallow extension regions with their high impurity concentration. This preliminary protection ensures that the carefully formed shallow regions maintain their intended impurity levels, enabling the transistor characteristics to be achieved without degradation from impurity loss.
3Ease of manufacture
If cleaning is performed to remove resist after plasma doping, then the substrate is cleaned, but approximately 43% of implanted boron is removed together with the resist
Solution Approach 1:
The protective film serves as an intermediary barrier during the cleaning process. It allows the cleaning solution to remove the resist effectively while preventing the boron impurities from being removed along with the resist. This resolves the contradiction between achieving thorough resist removal and preventing boron loss.
Solution Approach 2:
A thin protective film is applied to the semiconductor region, providing sufficient protection against impurity loss during cleaning while being thin enough to not interfere with the underlying device structure. This thin film approach enables effective resist removal without significant boron loss.
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 effectively reduces impurity loss during cleaning, enabling the formation of ultra-shallow extension regions with low resistance, thereby enhancing the desired characteristics of fin-type semiconductor devices, such as improved on-state current.
Implementation Method 1
implanting an impurity into the fin-type semiconductor region by a plasma doping process
Implementation Method 2
activating the impurity implanted into the fin-type semiconductor region by heat treatment
Data Source
AI summary
A fin-type semiconductor region (103) is formed on a substrate (101), and then a resist pattern (105) is formed on the substrate (101). An impurity is implanted into the fin-type semiconductor region (103) by a plasma doping process using the resist pattern (105) as a mask, and then at least a side of the fin-type semiconductor region (103) is covered with a protective film (107). Thereafter, the resist pattern (105) is removed by cleaning using a chemical solution, and then the impurity implanted into the fin-type semiconductor region (103) is activated by heat treatment.