Dual Gate Oxide Formation Using an Oxidized Inhibitor Layer
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Solution Overview
Problem
Forming gate dielectric layers with consistent thickness and reliability in semiconductor devices is challenging, particularly when requiring two different thicknesses, as existing methods increase cost and cycle time.
Innovation Solution
A method involving the formation of an inhibitor layer with silicon and nitrogen over a semiconductor material, followed by heating in an oxygen-containing ambient to oxidize the inhibitor layer and the semiconductor material, resulting in two dielectric layers with at least 90 weight percent silicon dioxide, where the second layer is thicker than the first.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate oxidation furnace processes are used to form gate dielectric layers with two different thicknesses, then the required thickness variation is achieved, but manufacturing cost and cycle time increase
Solution Approach 1:
The patent combines multiple oxidation processes into a single furnace process by using a nitride layer as a thickness control mechanism. Instead of performing separate oxidation processes for different thickness regions, the method uses selective nitride formation and removal to achieve variable thickness dielectric layers in one continuous process, thereby reducing cycle time while maintaining thickness adaptability.
Solution Approach 2:
The patent applies preliminary action by forming a nitride layer before the oxidation process to control the final dielectric thickness. The nitride layer acts as a sacrificial template that determines the oxidation depth and final dielectric thickness. This preliminary structuring enables precise thickness control without requiring multiple separate oxidation steps.
2Adaptability or versatility
If separate oxidation furnace processes are used to form gate dielectric layers with two different thicknesses, then the required thickness variation is achieved, but manufacturing cost increases
Solution Approach 1:
The patent merges multiple process steps into a single furnace-based oxidation process controlled by nitride layer formation. This consolidation reduces the number of separate furnace operations required, directly lowering manufacturing costs while maintaining the ability to produce dielectric layers with different thicknesses for various device functions.
Solution Approach 2:
The nitride layer serves multiple functions: it acts as a thickness control template, a protective layer during processing, and a sacrificial structure that enables variable thickness formation. This multi-functionality eliminates the need for separate specialized processes for each thickness requirement, reducing overall manufacturing complexity and cost.
3Adaptability or versatility
If conventional methods are used to form gate dielectric layers with two different thicknesses, then thickness variation is achieved, but thickness consistency and reliability deteriorate
Solution Approach 1:
The nitride layer serves as an intermediary that mediates between the oxidation process and the final dielectric thickness. By controlling nitride formation and removal, the method achieves precise control over oxidation depth and dielectric thickness uniformity. This intermediary mechanism enables consistent thickness control across different regions while maintaining the required thickness variation for different device functions.
Solution Approach 2:
The patent controls dielectric thickness by changing the nitride layer parameters (formation conditions, thickness, removal extent) rather than directly controlling oxidation time and temperature for each region. This parameter transformation enables precise and consistent thickness control through a single oxidation process, improving manufacturing precision while maintaining thickness adaptability.
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 achieves superior thickness consistency and dielectric reliability for both dielectric layers, improving the performance and efficiency of semiconductor devices by concurrently forming the first and second dielectric layers using the inhibitor layer.
Implementation Method 1
The semiconductor material is heated in an oxygen-containing ambient which oxidizes the inhibitor layer and forms the first dielectric layer
Implementation Method 2
oxidizes the semiconductor material to form the second dielectric layer
Implementation Method 3
The semiconductor material is heated in an oxygen-containing ambient
Data Source
AI summary
A semiconductor device including a first dielectric layer and a second dielectric layer is formed by forming an inhibitor layer over a semiconductor material. The inhibitor layer includes at least silicon and nitrogen. The semiconductor material is heated in an oxygen-containing ambient which oxidizes the inhibitor layer and forms the first dielectric layer which includes the oxidized inhibitor layer, and oxidizes the semiconductor material to form the second dielectric layer. The second dielectric layer is thicker than, the first dielectric layer. The first dielectric layer and the second dielectric layer each include at least 90 weight percent silicon dioxide and less than 1 weight percent nitrogen. The first dielectric layer and the second dielectric layer may be used to form gate dielectric layers for a first MOS transistor and a second MOS transistor that operates at a higher voltage than the first MOS transistor.