Gate Insulating Layer Layout to Suppress Active-Area Silicon Oxidation
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Solution Overview
Problem
The reduction in size of transistors leads to silicon loss and oxidation in active areas, affecting the operational characteristics of semiconductor devices due to the chemical change of silicon, which deteriorates the current flow and transistor performance.
Innovation Solution
A semiconductor device design featuring a substrate with element isolation layers and gate structures comprising a first region with a lower concentration of a first material and a second region with a higher concentration of a second material, where the gate insulating layer's thickness varies to minimize silicon oxidation and loss, and a method for fabricating this device by forming a barrier layer and gate insulating layer with specific material concentrations and thicknesses to prevent excessive silicon oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transistor size is reduced to increase integration, then the area of active areas is reduced, but silicon loss and oxidation in active areas increases, deteriorating transistor performance
Solution Approach 1:
The gate insulating layer is designed with non-uniform thickness, where the first region (over active area) has smaller thickness and the second region (over non-active area) has larger thickness. This local differentiation allows sufficient oxidation protection where needed while maintaining transistor performance in the active region.
Solution Approach 2:
The gate insulating layer is formed before the oxidation process to prevent silicon oxidation in advance. By preparing the protective layer beforehand, the patent prevents silicon loss during subsequent processing steps.
2Loss of substance
If the gate insulating layer thickness is increased to prevent silicon oxidation, then silicon loss is reduced, but the transistor operational characteristics deteriorate due to excessive thickness
Solution Approach 1:
The gate insulating layer thickness is locally optimized: the first region over the active area has smaller thickness (50-150 nm) to maintain transistor performance, while the second region over non-active areas has larger thickness (150-300 nm) to prevent silicon oxidation. This resolves the contradiction by applying different thicknesses to different functional regions.
Solution Approach 2:
The gate insulating layer is segmented into two distinct regions with different thicknesses. The first region provides minimal necessary protection over active areas, while the second region provides enhanced protection over non-active areas, allowing each region to be optimized for its specific function.
3Ease of manufacture
If a uniform gate insulating layer is used, then the manufacturing process is simplified, but silicon oxidation occurs in active areas affecting current flow
Solution Approach 1:
While the gate insulating layer is formed using a uniform deposition process (maintaining ease of manufacture), the underlying active area pattern and selective oxidation conditions create local thickness variations. The first region over active areas has smaller effective thickness, while the second region over non-active areas has larger thickness, providing localized oxidation protection without complicating the deposition process.
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 suppresses silicon loss and oxidation, maintaining the integrity of the active area and improving the operational characteristics of transistors by reducing defects in gate trench filling and enhancing contact resistance.
Implementation Method 1
a gate insulating layer comprising a first region containing a first material and a second region containing a second material different from the first material on the active area
Implementation Method 2
During the oxidation process, silicon in the active area may be oxidized, where the silicon (Si) in an active area is changed chemically
Data Source
AI summary
Provided is a semiconductor device. The semiconductor device includes a substrate including an element isolation layer defining a plurality of active areas, and a plurality of gate structures intersecting the active areas. Each of the gate structures includes a gate insulating layer including a first region containing a first material and a second region containing a second material different from the first material on the active area, and a gate electrode layer on the gate insulating layer. A concentration of the second material in the first region is less than a concentration of the second material in the second region, and a thickness of the first region is less than a thickness of the second region.