Vertical Semiconductor Die Layout for Low-Inductance Current Paths
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Solution Overview
Problem
Existing semiconductor dies with vertical transistor devices face challenges in efficiently managing current paths and reducing loop inductance, particularly when used as high-side switches in step-down converters, due to the limitations of traditional body diodes.
Innovation Solution
Integration of a diode with its cathode contact connected to the source region of the vertical transistor device, along with electrical isolation between the transistor and diode areas, allows for an alternative current path and reduced loop inductance by using a deep trench isolation to create a U-shaped current path through the semiconductor body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional body diode configuration is used in a vertical transistor device, then the device structure is simple, but the loop inductance is high and switching losses increase
Solution Approach 1:
The patent merges the diode and transistor into a single integrated device structure where the diode is formed within the same semiconductor body as the vertical transistor. The diode's cathode is connected to the transistor's source region, creating a compact integrated configuration that reduces loop inductance and switching losses while maintaining structural efficiency
2Reliability
If electrical isolation is implemented between transistor and diode areas, then current path control is improved, but device complexity increases
Solution Approach 1:
The patent segments the semiconductor device into distinct functional areas: a first area for the vertical transistor and a second area for the diode. These areas are electrically isolated from each other through deep trench isolation that extends through the semiconductor body, allowing independent control and optimization of each component while maintaining compact integration
Solution Approach 2:
The deep trench isolation structure acts as an intermediary element between the transistor and diode areas. This isolation trench, filled with insulating material, provides electrical separation while allowing the two components to be closely integrated in space, thus controlling current paths without excessive complexity
3Loss of energy
If the diode cathode is connected to the transistor source region, then loop inductance is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The diode and transistor are merged into a single integrated structure during the manufacturing process. The diode's cathode region is formed to directly contact or closely approach the transistor's source region within the same semiconductor body, eliminating the need for separate external connections and reducing loop inductance while managing manufacturing precision through integrated fabrication
4Reliability
If deep trench isolation is used to separate transistor and diode areas, then electrical isolation is improved, but manufacturing complexity increases
Solution Approach 1:
The semiconductor device is segmented into electrically isolated regions using deep trenches that extend through the semiconductor body. These trenches are filled with insulating material to provide robust electrical separation between the transistor and diode areas, achieving high isolation performance through structured segmentation
Solution Approach 2:
The deep trench isolation structure serves multiple functions: it provides electrical isolation between the transistor and diode, defines the boundaries of separate functional areas, and supports the integrated configuration of both components. This multi-functional approach achieves reliable isolation while streamlining the overall manufacturing process
Data Source
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AI summary
The disclosure relates to a semiconductor die (1) with a semiconductor body (2), the semiconductor die (1) comprising a vertical transistor device (10) formed in a first area (11) of the semiconductor body (2), the vertical transistor device (10) comprising a source region (15) at a first side (2.1) of the semiconductor body (2), and a drain region (16) at a second side (2.2) of the semiconductor body (2); a first electrical isolation (40) between the first area (11) and a second area (12) of the semiconductor body (2); and a diode (50) in the second area (12) of the semiconductor body (2); wherein a cathode contact (62) of the diode (50) is electrically connected to the source region (15) of the vertical transistor device (10).