Gate Structure Manufacturing Method for Trench MOSFETs
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Solution Overview
Problem
The conventional manufacturing process for step gate structures in trench MOSFETs is complex and costly, requiring two trench etching steps and multiple layer formations, which complicates the process and increases production costs.
Innovation Solution
A simplified manufacturing method that involves forming a mask oxide layer, etching a trench, depositing a bottom oxide layer, forming a silicon nitride layer to protect it, removing part of the bottom oxide layer, and then forming a gate oxide layer, allowing for the creation of a stepped gate structure with only one trench etching step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If two trench etching steps are performed to form a step gate structure, then the gate structure can be formed with stepped shape, but the manufacturing process becomes complicated and production cost increases
Solution Approach 1:
A preliminary oxide layer is formed on the substrate before trench etching. This oxide layer serves as a sacrificial layer that is later selectively removed to create the stepped gate structure. By performing this preliminary action, the need for multiple trench etching steps is eliminated, simplifying the manufacturing process while still achieving the desired stepped shape.
Solution Approach 2:
The preliminary oxide layer acts as an intermediary element that facilitates the formation of the stepped gate structure. It is deposited before etching, protects certain areas during the etching process, and is subsequently removed to reveal the stepped configuration. This intermediary layer enables the stepped structure to be formed through a single etching step rather than requiring multiple etching operations.
2Shape
If two trench etching steps are performed with compound deposition protection, then the stepped gate structure is formed, but production cost increases
Solution Approach 1:
The preliminary oxide layer is formed in advance before the trench etching process. This pre-formed layer eliminates the need for subsequent compound deposition and removal steps that would be required in conventional two-etching processes. By performing this action preliminarily, manufacturing steps are reduced and production cost is lowered.
Solution Approach 2:
The preliminary oxide layer serves as a sacrificial or disposable layer that is intentionally removed after serving its protective function during etching. By discarding this temporary layer, the stepped structure is revealed without requiring expensive multi-step protection and deprotection processes. This approach reduces manufacturing complexity and cost.
3Productivity
If the bottom oxide layer is removed partially, then only one trench etching is needed, but additional steps for protecting and removing oxide layers are required
Solution Approach 1:
The formation of the preliminary oxide layer is merged with the substrate preparation process, and its removal is merged with the gate structure formation process. By combining these functions, the overall process efficiency is improved. The preliminary oxide layer serves multiple purposes: it protects the substrate during etching and its selective removal creates the stepped structure, eliminating the need for separate protection and deprotection steps.
Solution Approach 2:
The preliminary oxide layer performs multiple functions: it acts as a protective layer during trench etching, serves as a sacrificial layer to define the stepped structure, and eliminates the need for separate compound deposition and removal steps. This multi-functionality reduces the total number of process steps while maintaining manufacturing 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 method simplifies the gate structure process, reduces production costs, and enables the formation of a step gate structure with improved electrical characteristics for semiconductor components.
Implementation Method 1
forming a silicon nitride layer to protect the bottom oxide layer
Implementation Method 2
performing a photolithography process on the mask oxide layer and the substrate to form a trench
Implementation Method 3
etching the trench
Data Source
AI summary
A manufacturing method of a gate structure includes steps of forming a mask oxide layer on the substrate, performing a photolithography process on the mask oxide layer and the substrate to form a trench, etching the trench, removing the mask oxide layer, forming a bottom oxide layer on a surface of the substrate and a trench surface of the trench, forming a silicon nitride layer on the trench, removing a part of the bottom oxide layer, removing the silicon nitride layer, forming a gate oxide layer on the surface and a part of the trench surface, and forming a poly layer on the trench. Therefore, the advantages of simplifying the gate structure process and reducing the production cost are achieved.