Semiconductor Gate Sidewall Formation via Selective Insulating Film Etching
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Solution Overview
Problem
The miniaturization of semiconductor devices leads to challenges in forming low breakdown voltage MISFETs, as the reduced gap between gate electrodes can result in sidewall embedding, making it difficult to accurately form narrow sidewalls using etching methods, which affects the normal formation of these devices.
Innovation Solution
A method involving the sequential formation of silicon nitride and silicon oxide films on gate electrodes, followed by selective removal and reformation to create distinct sidewalls with varying widths, preventing sidewall embedding and enabling precise sidewall formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the interval between gate electrodes is reduced for miniaturization, then device integration density is improved, but sidewall embedding occurs making it difficult to form narrow sidewalls accurately
Solution Approach 1:
The insulating film is divided into multiple layers with different etch selectivities (first insulating film with first etch selectivity, second insulating film with second etch selectivity). This segmentation allows selective removal of the first insulating film while preserving the second, enabling precise sidewall formation even when gate electrode intervals are reduced for miniaturization.
Solution Approach 2:
Different regions of the structure receive different treatments through the multi-layer insulating film approach. The first insulating film is selectively removed in certain areas to form narrow sidewalls, while the second insulating film remains to provide structural support and prevent embedding, achieving local optimization of sidewall dimensions.
2Length of moving object
If etching is used to reduce sidewall width for low breakdown voltage MISFET, then narrow sidewalls are formed, but sidewall embedding occurs making normal device formation difficult
Solution Approach 1:
The second insulating film is formed in advance before the first insulating film is selectively removed. This preliminary action ensures that the structural support layer is already in place to prevent embedding during the subsequent selective removal process, guaranteeing reliable device formation.
Solution Approach 2:
The second insulating film acts as an intermediary structure between the gate electrode and the removed first insulating film. It provides mechanical support during the selective removal process, preventing the gate electrode sidewalls from embedding while still allowing the first insulating film to be removed to form narrow sidewalls.
3Device complexity
If a single insulating film is used for sidewall formation, then process complexity is reduced, but selective sidewall formation for different transistor types becomes difficult
Solution Approach 1:
The invention changes the etch selectivity parameter by using insulating films with different etch selectivities. This allows the same multi-layer structure to be processed differently in different regions, enabling selective sidewall formation for both low breakdown voltage and high breakdown voltage transistors without requiring completely different process flows.
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 improves the performance of semiconductor devices by allowing for the accurate formation of sidewalls, enhancing the integration density, reducing power consumption, and maintaining high-speed operation while securing the breakdown voltage requirements for both low and high breakdown voltage transistors.
Implementation Method 1
a silicon nitride film and a first silicon oxide film are sequentially formed so as to cover each sidewall of a first gate electrode and a second gate electrode
Implementation Method 2
a silicon nitride film and a first silicon oxide film are sequentially formed so as to cover each sidewall of a first gate electrode and a second gate electrode
Data Source
AI summary
Deterioration in reliability is prevented regarding a semiconductor device. The deterioration is caused when an insulating film for formation of a sidewall is embedded between gate electrodes at the time of forming sidewalls having two kinds of different widths on a substrate. A sidewall-shaped silicon oxide film is formed over each sidewall of a gate electrode of a low breakdown voltage MISFET and a pattern including a control gate electrode and a memory gate electrode. Then, a silicon oxide film beside the gate electrode is removed, and a silicon oxide film is formed on a semiconductor substrate, and then etchback is performed. Accordingly, a sidewall, formed of a silicon nitride film and the silicon oxide film, is formed beside the gate electrode, and a sidewall, formed of the silicon nitride film and the silicon oxide films, is formed beside the pattern.