Power Diode Spacer Region for Ion Implantation Alignment
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Solution Overview
Problem
Conventional power diodes suffer from non-optimum electrical characteristics, particularly in blocking capability and switch-off performance, due to the extension of the lifetime control region into the field-limiting junction termination region during ion implantation, which negatively affects the safe operating area and blocking capability.
Innovation Solution
A spacer region is introduced between the anode layer and the junction termination region, with a shadow mask protecting the junction termination region from ion implantation, ensuring the lifetime control region is restricted to the active area, thereby preventing misalignment and maintaining optimal electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If ion implantation is performed across the entire anode side surface to create a lifetime control region, then switch-off performance is improved, but blocking capability and safe operating area deteriorate due to extension into the junction termination region
Solution Approach 1:
The patent segments the treatment area by introducing a spacer region that divides the anode side surface into two distinct zones: the active area where lifetime control region is formed by ion implantation, and the junction termination region where implantation is prevented. This segmentation allows selective application of ion implantation to improve switch-off performance in the active area while preserving blocking capability in the termination region.
Solution Approach 2:
The patent applies local quality by creating different structural characteristics in different regions of the device. The spacer region introduces a localized structural modification that prevents ion implantation from extending into the junction termination region, thereby maintaining different electrical properties (lifetime control vs. field termination) in adjacent areas without mutual interference.
2Ease of manufacture
If the lifetime control region extends into the junction termination region, then manufacturing simplicity is maintained, but electrical characteristics such as blocking capability and safe operating area are degraded
Solution Approach 1:
The patent applies preliminary action by introducing the spacer region structure before performing ion implantation. This pre-structured barrier ensures that during the subsequent ion implantation process, the lifetime control region is automatically confined to the active area without requiring complex masking or alignment procedures, thus maintaining manufacturing simplicity while achieving precise electrical characteristic control.
3Device complexity
If no spacer region is introduced, then device structure remains simple, but alignment errors during ion implantation cause lifetime control region to encroach on junction termination region
Solution Approach 1:
The spacer region acts as an intermediary buffer zone between the active area and the junction termination region. This intermediate structure provides a physical barrier that prevents ion implantation from reaching the termination region, thereby compensating for any alignment errors during the ion implantation process without requiring high-precision alignment equipment or complex procedures.
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 enhances the electrical blocking capability and switch-off performance by isolating the lifetime control region from the junction termination region, resulting in improved electrical characteristics and reduced leakage current levels, independent of hydrogen dose and spacer width.
Implementation Method 1
a lifetime control region 134 may be generated close to the anode side surface of the diode 101 by implanting defects into an adjacent active area 30
Implementation Method 2
a shadow mask 40 protecting the junction termination region 24 during an ion implantation procedure
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A power semiconductor device (1), e.g. a power diode, and a method for producing such device is proposed. The device comprises a first layer (2) of a first conductivity type, a second layer (10) of a second conductivity type arranged in a central region (22) on a first main side (8) of the first layer (2), a third electrically conductive layer (16) arranged on the second layer (2) and a fourth electrically conductive layer (14) arranged on the first layer (2) at a second main side (12) opposite to the first main side (8). The device further comprises a junction termination region (24) surrounding the second layer (10) with self contained sub-regions (26) of the second conductivity type. Furthermore, a spacer region (42) is arranged between the second layer (10) and the junction termination region (24) and comprises a self-contained spacer sub-region (36) of the second conductivity type which is electrically disconnected from the second layer (10). This spacer sub-region (36) has a width enabling a reliable alignment of a shadow mask (40) during an ion implantation such that an implanted lifetime control region (34) comprising carrier lifetime reducing defects may be restricted to a central area (22) while no such defects are implanted into the junction termination region (24). Thereby, electrical characteristics such as a blocking capability of the diode are improved.