Semiconductor Isolation Structure for DTI Electric Field Relief
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Solution Overview
Problem
Conventional semiconductor device isolation structures experience electric field concentration at the interface of the buried layer and DTI region, leading to deteriorated isolation characteristics, particularly in BCDMOS processes requiring high breakdown voltages.
Innovation Solution
A semiconductor device isolation structure is proposed with an ion implantation region formed under the buried layer within the substrate, mitigating electric field concentration by enhancing isolation characteristics, and incorporating a gap-fill region formed through epitaxial growth for easy filling of deep trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DTI region is formed from the surface to a predetermined depth to prevent leakage current, then electrical isolation between adjacent devices is improved, but electric field concentration occurs at the interface where the buried layer and DTI region meet, deteriorating isolation characteristics
Solution Approach 1:
An ion implantation region of the second conductivity type is formed in advance within the substrate at a position corresponding to the future buried layer location. This preliminary doping creates a transition zone that mitigates electric field concentration before the buried layer and DTI region are formed, preventing the harmful effect from occurring in the first place
Solution Approach 2:
The ion implantation region is localized specifically within the substrate at the interface area where the buried layer and DTI region will meet. By concentrating the doping action in this specific local region, the electric field distribution is optimized precisely where needed without affecting other areas of the device
2Ease of manufacture
If the ion implantation region is formed after the buried layer is formed, then the process sequence is simpler, but it becomes difficult to form the ion implantation region at the desired depth in the substrate
Solution Approach 1:
The ion implantation region is formed as a preliminary step before the buried layer is created. This sequencing allows precise depth control of the ion implantation region relative to the substrate, as the implantation is performed on the bare substrate where depth positioning can be accurately controlled, rather than attempting to position it relative to an already-formed buried layer
3Reliability
If a deep trench is formed to create the DTI region, then electrical isolation is achieved, but the gap-fill process within the deep trench becomes difficult
Solution Approach 1:
A gap-fill region is formed through epitaxial growth within the deep trench before the final DTI structure is completed. This preliminary gap-fill action creates a foundation layer that simplifies subsequent filling operations, making the overall gap-fill process easier despite the deep trench geometry
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 structure effectively reduces electric field concentration at the interface of the buried layer and DTI region, improving isolation characteristics and facilitating easy gap-fill processes in deep trenches.
Implementation Method 1
an ion implantation region is formed under a buried layer within a substrate in which a DTI region is formed to mitigate electric field concentration
Implementation Method 2
a gap-fill region is formed through a substrate under a deep trench by epitaxial growth
Data Source
AI summary
In a semiconductor device isolation structure and a method of manufacturing the same, an ion implantation region is formed under a buried layer within a substrate in which a DTI region is formed to mitigate electric field concentration on a side on which the DTI region and the buried layer are in contact with each other or adjacent to each other, thereby enhancing isolation characteristics.