Back Surface Hole Injection Diode Segmentation
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Solution Overview
Problem
Back surface hole injection type diodes face issues with increased forward voltage drop, large recovery losses, and noise generation due to the arrangement of the P-type layer at the back surface of the semiconductor substrate, which affects the diode's performance and efficiency.
Innovation Solution
The semiconductor device incorporates a P-type anode layer on the main surface, an N-type cathode layer on the back surface, a first P-type layer at the back surface alongside the cathode layer, and a second P-type layer on the main surface above the first P-type layer, optimizing the hole injection effect and reducing the area occupancy of the back surface P-type layer to minimize forward voltage drop and enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a P-type layer is arranged in the back surface of the semiconductor substrate for hole injection, then the hole injection effect is improved, but the forward voltage drop increases and the area right above the P-type layer hardly functions as a diode
Solution Approach 1:
The P-type layer is segmented into two separate layers: a first P-type layer in the back surface and a second P-type layer in the main surface. This segmentation allows the back surface P-type layer to provide hole injection while the second P-type layer in the main surface restores the diode function in the area above, preventing the formation of a non-functional region and reducing forward voltage drop.
Solution Approach 2:
The solution extends the structure from a single-layer back surface configuration to a multi-layer configuration spanning both the back surface and main surface of the semiconductor substrate. By adding the second P-type layer in the main surface above the first P-type layer, the invention utilizes the third dimension (depth) to resolve the contradiction between hole injection and diode functionality.
2Reliability
If a P-type layer is arranged in the back surface of the semiconductor substrate, then hole injection is enhanced, but recovery losses increase and ringing noise is generated
Solution Approach 1:
The P-type layer is divided into first and second P-type layers positioned at different surfaces. This segmentation enables the first P-type layer in the back surface to provide controlled hole injection while the second P-type layer in the main surface helps suppress ringing noise and reduce recovery losses by improving the overall carrier distribution and reducing abrupt carrier removal during recovery operation.
3Reliability
If the area occupancy of the back surface P-type layer is increased to improve hole injection, then the hole injection effect is enhanced, but the forward voltage drop increases
Solution Approach 1:
The P-type layer is segmented into two separate layers located at different surfaces of the semiconductor substrate. This allows the first P-type layer in the back surface to provide hole injection with optimized area occupancy, while the second P-type layer in the main surface ensures that the area above functions properly as a diode, preventing excessive forward voltage drop even when the back surface P-type layer has significant area occupancy.
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 configuration improves the diode's performance by reducing the forward voltage drop, minimizing recovery losses, and suppressing ringing noise, while allowing for sufficient hole injection and miniaturization of the diode, thus achieving better efficiency and reliability.
Implementation Method 1
a P-type layer for injecting holes into the cathode layer in the back surface at the time of the recovery operation is arranged in the back surface
Data Source
AI summary
In a back surface hole injection type diode, by more effectively securing the effect of hole injection from the back surface of a semiconductor substrate, the performance of a semiconductor device is improved. In the semiconductor device, in a diode formed of a P-N junction including an anode P-type layer formed in the main surface of a semiconductor substrate and a back surface N+-type layer formed in the back surface of the semiconductor substrate, a back surface P+-type layer is formed in the back surface, and a surface P+-type layer is formed in the main surface right above the back surface P+-type layer to thereby promote the effect of hole injection from the back surface.