Semiconductor Device Rear-Surface Ion Implantation for Buried Diffusion Layers
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Solution Overview
Problem
The conventional method for manufacturing semiconductor devices with buried diffusion layers is lengthy and costly due to the need for a thick epitaxial layer and multiple processing steps.
Innovation Solution
A method involving ion-implantation of impurities from the rear surface of the semiconductor substrate to form the buried diffusion layer, simplifying the procedure and reducing manufacturing costs by eliminating the need for a thick epitaxial layer and reducing the number of processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick epitaxial layer is formed on the semiconductor substrate to create a buried diffusion layer, then the electrical isolation and parasitic transistor suppression are improved, but the manufacturing procedure is prolonged and manufacturing cost increases
Solution Approach 1:
Instead of forming the buried diffusion layer from the front surface through a thick epitaxial layer, the patent applies ion implantation from the rear surface of the semiconductor substrate. This inverted approach directly creates the buried diffusion layer at the desired depth without requiring a thick epitaxial layer, thereby shortening the manufacturing procedure while maintaining electrical isolation functionality.
Solution Approach 2:
The patent changes the method of buried diffusion layer formation from epitaxial growth to ion implantation. This parameter change in the manufacturing process allows direct formation of the buried diffusion layer with controlled depth and concentration through ion implantation from the rear surface, eliminating the need for a thick epitaxial layer and reducing manufacturing time.
2Reliability
If a thick epitaxial layer is formed on the semiconductor substrate to create a buried diffusion layer, then the electrical isolation and parasitic transistor suppression are improved, but the manufacturing cost increases
Solution Approach 1:
The patent inverts the conventional approach by forming the buried diffusion layer from the rear surface through ion implantation rather than growing a thick epitaxial layer from the front surface. This inversion eliminates unnecessary material growth steps and reduces manufacturing complexity, thereby lowering production costs while achieving the same electrical isolation effect.
Solution Approach 2:
The patent extracts the essential function of buried diffusion layer formation from the complex epitaxial growth process. By using ion implantation from the rear surface, the patent isolates and simplifies the key step of creating the buried diffusion layer, removing the need for a thick epitaxial layer and associated processing steps, thus reducing manufacturing cost.
3Productivity
If ion implantation is performed from the rear surface to form the buried diffusion layer, then the manufacturing procedure is simplified and cost is reduced, but the impurity concentration control must be precisely managed
Solution Approach 1:
The patent replaces the mechanical/chemical process of epitaxial growth with ion implantation technology. This substitution allows precise control of impurity concentration through well-established ion implantation parameters (energy, dose, temperature annealing), achieving both high productivity and precise manufacturing control through a more controllable physical 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 simplifies the manufacturing process, reduces costs, and allows for the electrical isolation of well regions from the semiconductor substrate, enabling separate back-gate potential application, thus improving the efficiency and cost-effectiveness of semiconductor device production.
Implementation Method 1
ion-implanting impurities of the second conductivity type from the second principal surface of the polished semiconductor substrate to form the third semiconductor region
Implementation Method 2
polishing a second principal surface opposite to the first principal surface of the semiconductor substrate above which at least the source region, the drain region, and the gate electrode are formed to thin the semiconductor substrate
Data Source
AI summary
The semiconductor device includes: an epitaxial layer of a first conductivity type formed on a first principal surface of a semiconductor substrate; a first semiconductor region of the first conductivity type formed from an outermost surface to an inner portion of the epitaxial layer; and a third semiconductor region of a second conductivity type formed from a bottom surface of the first semiconductor region to an inner portion of the semiconductor substrate. The method includes: (a) polishing a second principal surface opposite to the first principal surface of the semiconductor substrate above which at least a source region, a drain region, and a gate electrode are formed to thin the substrate; and (b) ion-implanting impurities of the second conductivity type from the second principal surface of the polished semiconductor substrate to form the third semiconductor region.