Gate Trench Oxide Profile for Lower GIDL in Semiconductor Structures
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Solution Overview
Problem
Semiconductor structures face issues with gate-induced drain leakage (GIDL) and low turn-on sensitivity of transistors, primarily due to the difficulty in forming an oxide layer with a thin bottom and thick sidewalls in standard processes.
Innovation Solution
A method is introduced where a first initial doped region is formed at the bottom of a trench, followed by oxidation, which results in a first oxide layer with a greater thickness than the second oxide layer, reducing GIDL and improving turn-on sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate trench is formed on the substrate and a gate oxide layer and gate are formed in the gate trench, then the transistor structure is completed, but gate induced drain leakage current occurs, affecting transistor turn-on sensitivity and reducing semiconductor structure yield
Solution Approach 1:
The patent applies local quality by creating different oxide layer thicknesses at different locations within the gate trench. Specifically, a first oxide layer with greater thickness is formed on the sidewalls of the gate trench, while a second oxide layer with lesser thickness is formed at the bottom. This non-uniform oxide layer distribution locally addresses the GIDL problem at the drain-gate interface while maintaining proper gate control, thereby reducing gate induced drain leakage current and improving transistor turn-on sensitivity
Solution Approach 2:
The patent employs preliminary action by forming a doped region at the bottom of the gate trench before oxidization. This pre-doping step modifies the chemical composition and oxidation characteristics of the substrate at the trench bottom, enabling differential oxidation rates between the sidewalls and bottom during subsequent oxidization processes. This preliminary modification ensures the formation of the desired non-uniform oxide layer structure that reduces GIDL
2Manufacturing precision
If standard oxidation processes are used to form oxide layers in the gate trench, then the oxidation process is simple, but it is difficult to form an oxide layer with thin bottom and thick sidewalls
Solution Approach 1:
The patent achieves precise control over oxide layer thickness distribution by creating local differences in the substrate composition before oxidation. A doped region is formed at the bottom of the gate trench with different oxidation characteristics compared to the sidewall substrate. During oxidation, this local compositional difference results in slower oxidation at the bottom and faster oxidation on the sidewalls, producing the desired thin-bottom/thick-sidewall oxide structure through a relatively simple single-step oxidation process
Solution Approach 2:
The patent utilizes parameter changes by modifying the chemical composition parameter of the substrate through doping at the trench bottom. This compositional parameter change alters the oxidation rate parameter, creating a differential oxidation behavior between the trench bottom and sidewalls. By controlling the doping concentration and distribution, the oxidation kinetics are tuned to achieve the target oxide layer thickness profile without requiring complex multi-step oxidation processes
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 method effectively reduces gate-induced drain leakage and enhances the turn-on sensitivity of semiconductor structures, thereby improving their yield.
Implementation Method 1
oxidizing the first trench, forming a first oxide layer on the sidewalls of the first trench, and forming a second oxide layer at the bottom of the first trench... the oxidation rate of the first initial doped region is lower than the oxidation rate of the substrate
Data Source
AI summary
The disclosed method provides a solution to the gate-induced drain leakage (GIDL) current in a semiconductor structure. The method includes forming a first trench with a first initial doped region at its bottom, oxidizing the first trench, forming a first oxide layer on the sidewalls of the first trench, and forming a second oxide layer at the bottom of the first trench. The first oxide layer's thickness is greater than the second oxide layer's thickness. The doping element of the first initial doped region prolongs the reduction rate, so that the oxidation rate of the first initial doped region is lower than the oxidation rate of the substrate, thereby forming the first oxide layer. The GIDL of the semiconductor structure can be reduced, the turn-on sensitivity of the semiconductor structure can be improved, and the yield of the semiconductor structure can be increased.