Semiconductor Integrated Circuit Device With Buried Impurity Layer
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Solution Overview
Problem
Existing semiconductor integrated circuit devices face challenges in efficiently integrating high-voltage and low-voltage transistors with stable device characteristics due to variations in impurity concentrations and diffusion processes, affecting breakdown voltage and surface electric-field performance.
Innovation Solution
A method involving a first conductivity type substrate with a buried impurity layer formed using blank implant and a subsequent drive-in diffusion process, followed by the formation of epitaxial layers with controlled impurity concentrations to create high-voltage and low-voltage semiconductor devices, with device isolation regions to maintain stable performance across voltage ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high-voltage and low-voltage transistors are integrated on the same substrate, then device functionality and versatility are improved, but variations in impurity concentrations cause instability in device characteristics
Solution Approach 1:
The patent implements local quality by creating distinct impurity concentration zones within the substrate. A buried impurity layer with high concentration is formed only in the high-voltage device region, while the low-voltage device region maintains lower impurity concentration. This spatial differentiation of impurity concentrations allows each device type to operate with optimal characteristics, resolving the contradiction between integration versatility and characteristic stability.
2Ease of manufacture
If blanket implant is used to form buried impurity layer, then manufacturing process simplicity is improved, but imprecise control of impurity concentration distribution occurs
Solution Approach 1:
The patent applies preliminary action by forming the buried impurity layer through blanket implantation before the epitaxial growth step. The high-concentration impurity layer is pre-formed in the substrate, and then the epitaxial layer is grown over it. This sequence allows the impurity concentration profile to be established early in the process, simplifying manufacturing while the subsequent epitaxial growth with controlled doping compensates for any imprecision, achieving both ease of manufacture and adequate precision.
3Manufacturing precision
If drive-in diffusion process is performed on buried impurity layer, then impurity concentration distribution is improved, but process complexity increases
Solution Approach 1:
The patent utilizes parameter changes by controlling the temperature and duration of the drive-in diffusion process to achieve the desired impurity concentration profile. By optimizing these thermal parameters, the high-concentration impurity layer is effectively distributed into the epitaxial layer to form the required junction depths and concentrations. This approach improves manufacturing precision through parameter optimization without significantly increasing device structural complexity.
4Reliability
If epitaxial layer with controlled impurity concentration is formed, then breakdown voltage performance is improved, but manufacturing steps increase
Solution Approach 1:
The patent applies preliminary action by pre-forming the buried impurity layer in the substrate before epitaxial growth. This preliminary impurity layer serves as a foundation that controls the final impurity concentration profile in the epitaxial layer. By establishing the impurity distribution early, the subsequent epitaxial growth can be optimized for breakdown voltage performance without requiring additional complex post-processing steps, thus improving reliability while managing manufacturing complexity.
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 enables the fabrication of semiconductor integrated circuit devices with improved breakdown voltage and stable current characteristics by accurately controlling impurity concentrations and preventing defects, ensuring effective isolation between high-voltage and low-voltage transistors.
Implementation Method 1
implanting a first conductivity type impurity into an entire surface of the substrate at a first dose
Implementation Method 2
diffusing the first conductivity type impurity
Data Source
AI summary
A semiconductor integrated circuit device and method of fabricating a semiconductor integrated circuit device, the method including preparing a first conductivity type substrate including a first conductivity type impurity such that the first conductivity type substrate has a first impurity concentration; forming a buried impurity layer using blank implant such that the buried impurity layer includes a first conductivity type impurity and has a second impurity concentration higher than the first impurity concentration; forming an epitaxial layer on the substrate having the buried impurity layer thereon; and forming semiconductor devices and a device isolation region in or on the epitaxial layer.