Semiconductor Device Deep P-Type Layer Breakdown Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In thin wafer power semiconductor devices, reducing substrate thickness increases the likelihood of secondary breakdown current flow and decreases breakdown resistance, particularly under cosmic ray irradiation, leading to local breakdown effects such as single event burnout.
Innovation Solution
A semiconductor device design featuring an n-type semiconductor substrate with a p-type layer deeper than the n-type buffer layer in the termination region, which redirects secondary breakdown current to flow obliquely across the substrate thickness, preventing negative resistance and enhancing breakdown resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If substrate thickness is reduced to improve performance, then device performance is improved, but breakdown resistance decreases and secondary breakdown current is more likely to flow
Solution Approach 1:
The patent introduces a deep p-type layer extending to the lower surface of the substrate, adding a vertical dimension to the breakdown prevention mechanism. This deep layer creates an oblique current path that extends the breakdown distance without increasing substrate thickness, thus maintaining high device performance while improving breakdown resistance.
Solution Approach 2:
The deep p-type layer acts as an intermediary structure between the upper and lower surfaces of the substrate. It mediates the breakdown process by providing a controlled path for secondary breakdown current, preventing direct local breakdown and converting harmful breakdown effects into a controlled phenomenon that enhances reliability.
2Loss of energy
If substrate thickness is reduced, then loss is reduced, but local breakdown effect (single event burnout) is more likely under cosmic ray irradiation
Solution Approach 1:
The patent converts the harmful local breakdown effect caused by cosmic rays into a beneficial controlled breakdown phenomenon. By introducing the deep p-type layer, secondary breakdown current is deliberately channeled through a controlled path, transforming the harmful single event burnout into a benign secondary breakdown that actually enhances device reliability under radiation conditions.
3Reliability
If secondary breakdown current flows locally, then breakdown resistance decreases, but current path can be elongated to prevent negative resistance
Solution Approach 1:
The deep p-type layer extending to the lower surface creates a three-dimensional oblique current path. This vertical dimension extends the breakdown distance without increasing the horizontal footprint, effectively elongating the current path to prevent negative resistance while maintaining compact device 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 design effectively increases breakdown resistance by elongating the current path and preventing local breakdowns, even under high-energy cosmic ray irradiation, thereby improving the device's performance and reliability.
Implementation Method 1
a secondary breakdown occurs between the main junction of the cell region of the upper surface of the substrate and the p-type layer of the termination region of the lower surface of the substrate
Data Source
AI summary
A semiconductor device includes: an n-type semiconductor substrate having a cell region and a termination region provided around the cell region; a p-type anode layer provided on an upper surface of the n-type semiconductor substrate in the cell region; an n-type buffer layer provided on a lower surface of the n-type semiconductor substrate; and a p-type layer provided on the lower surface of the n-type buffer layer in the termination region and deeper than the n-type buffer layer.