Memory Transistor Gate Protection During MOS Oxidation
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Solution Overview
Problem
The manufacturing processes of memory transistors and MOS transistors in semiconductor devices can lead to characteristic deterioration of memory transistors due to influences from oxidation treatments of MOS transistors, potentially causing 'bird's beak' issues.
Innovation Solution
A semiconductor device and manufacturing method that include forming a sacrificial polysilicon film on the surface region of the memory transistor's gate electrode and gate dielectric structure, which prevents oxidation treatment from affecting the memory transistor, thereby suppressing the generation of 'bird's beak'.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oxidation treatment is performed on MOS transistor after memory transistor structure is processed, then MOS transistor manufacturing is completed, but bird's beak occurs and memory transistor characteristics deteriorate
Solution Approach 1:
A sacrificial polysilicon film is introduced as an intermediary protective layer between the oxidation treatment process and the memory transistor gate electrode. This film acts as a barrier that prevents oxygen from reaching and oxidizing the memory transistor gate electrode during MOS transistor fabrication, thereby eliminating the bird's beak effect while allowing the oxidation treatment to proceed for MOS transistor manufacturing.
Solution Approach 2:
The sacrificial polysilicon film is formed on the memory transistor gate electrode before the oxidation treatment is applied to the MOS transistor. This preliminary protective action ensures that when the oxidation treatment occurs subsequently, the memory transistor gate electrode is already protected, preventing any harmful oxidation effects before they can occur.
2Adaptability or versatility
If memory transistor and MOS transistor are mixedly mounted on same substrate, then device integration is achieved, but oxidation treatment of MOS transistor affects memory transistor
Solution Approach 1:
The sacrificial polysilicon film is applied selectively only to the memory transistor gate electrode regions, not to the entire substrate or MOS transistor regions. This localized protective measure allows the oxidation treatment to proceed normally for MOS transistor fabrication while providing targeted protection only where needed - at the memory transistor gate electrodes - thus resolving the conflict between integrated manufacturing and preventing harmful oxidation effects.
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
The proposed solution effectively suppresses the characteristic deterioration of memory transistors by preventing oxidation-induced 'bird's beak' formation, ensuring improved performance and reliability of semiconductor devices.
Implementation Method 1
there is a risk that a bird's beak occurs and causes characteristic deterioration of the memory transistor due to influences of oxidation treatment of the MOS transistor
Data Source
AI summary
According to the present embodiment, a semiconductor device includes a semiconductor substrate, a memory transistor, and a MOS transistor. The memory transistor includes at least a first silicon dioxide film and a first gate electrode positioned on the semiconductor substrate in order. The MOS transistor includes a second silicon dioxide film and a second gate electrode positioned on the semiconductor substrate in order. Any bird's beak is not generated in at least either the first silicon dioxide film or the first gate electrode of the memory transistor.