Semiconductor Gate Oxide Thickness Control via Segmentation
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Solution Overview
Problem
The existing semiconductor devices, such as power transistors, face performance issues due to the thickness of the oxide layer on the gate electrode, which can be either over-etched or under-etched during the etching process, leading to defects and suboptimal device performance.
Innovation Solution
A method is developed to efficiently control the thickness of the oxide layer on the gate electrode by forming a first oxide layer, followed by a nitride layer, and then removing these layers to achieve a consistent thickness of about 180±30 Å, ensuring precise etching and maintaining device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick oxide layer (580±40 Å) is formed on the gate electrode during heat treatment and dopant diffusion, then the ESD protective circuit and dopant diffusion process are improved, but the oxide layer thickness deviates from the optimal range (180±30 Å), causing over-etching or under-etching defects
Solution Approach 1:
The oxide layer formation process is divided into multiple stages: first forming a thick oxide layer (580±40 Å) for ESD protection and dopant diffusion, then selectively removing portions to achieve the final optimal thickness (180±30 Å). This segmentation allows each stage to serve its specific function without compromising the other.
Solution Approach 2:
A thick oxide layer is formed in advance during heat treatment and dopant diffusion processes to ensure ESD protection and proper dopant distribution. This preliminary thick oxide layer serves as a protective and functional layer before the final thinning to 180±30 Å, ensuring that critical processes occur under optimal conditions before precision thickness control is applied.
2Manufacturing precision
If the oxide layer thickness is controlled to be thin (180±30 Å) for optimal device performance, then device performance is improved, but the oxide layer may be insufficient for ESD protection and dopant diffusion processes
Solution Approach 1:
The thick oxide layer (580±40 Å) is formed in advance to provide sufficient ESD protection and enable proper dopant diffusion. This preliminary thick layer ensures that protective and processing functions are fulfilled before the oxide is thinned to the optimal 180±30 Å for final device performance.
Solution Approach 2:
The oxide layer thickness control is segmented into two distinct phases: a first phase where a thick oxide layer is formed for ESD protection and dopant diffusion, and a second phase where the oxide is selectively removed to achieve the final thin thickness. This segmentation resolves the contradiction by allowing both thick and thin oxide requirements to be met at different stages.
3Manufacturing precision
If a thick oxide layer (580±40 Å) is etched to achieve the optimal thickness, then the oxide layer thickness is reduced, but over-etching or under-etching defects are generated due to the ±40 Å deviation
Solution Approach 1:
A thick oxide layer (580±40 Å) is formed in advance as a preliminary step, providing a sufficient thickness margin that accommodates the ±40 Å etching deviation. This preliminary thick layer ensures that even after etching, the final thickness will fall within the optimal range, preventing both over-etching and under-etching defects.
Solution Approach 2:
The process incorporates a thickness cushion by forming an initially thick oxide layer (580±40 Å) that provides a buffer against etching variability. This beforehand cushioning ensures that the ±40 Å etching deviation will not result in defects, as the extra thickness compensates for potential over-etching while still allowing achievement of the target 180±30 Å thickness.
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 allows for the precise control of the oxide layer thickness, preventing over-etching or under-etching, thereby enhancing the performance and reliability of semiconductor devices by maintaining a consistent oxide layer thickness.
Implementation Method 1
removing the nitride layer and the second oxide layer from the first oxide layer
Implementation Method 2
forming a thin oxide layer by partially removing the first oxide layer
Implementation Method 3
implanting second conductive-type impurity ions into the semiconductor substrate including the first oxide layer
Implementation Method 4
forming a first oxide layer on the semiconductor substrate including the gate electrodes
Data Source
AI summary
A method of manufacturing a semiconductor device including forming a first conductive-type buried layer in a substrate; forming a first conductive-type drift area on the first conductive-type buried layer; forming a gate insulating layer and gate electrodes by selectively removing the first conductive-type drift area; forming a first oxide layer on the substrate and gate electrodes; implanting second conductive-type impurity ions into the substrate; forming a nitride layer on the first oxide layer; forming a second conductive-type well by diffusing the second conductive-type impurity ions while forming a second oxide layer; removing the nitride layer, the second oxide layer, and portions of the first oxide layer; forming first conductive-type source areas at sides of the gate electrode(s); forming a dielectric layer on the oxide layer; forming a trench in the dielectric layer and the oxide layer; forming a source contact in the trench; and forming a drain.