Vertical MOSFET Field Plate Electrode for Gate Connection Failure Detection
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Solution Overview
Problem
Existing semiconductor devices, particularly vertical MOSFETs, face challenges in reliably detecting electrical connection failures between the gate pad and gate electrode before packaging, which can lead to reduced withstand voltage due to floating field plate electrodes and increased likelihood of connection failures near the chip's periphery.
Innovation Solution
The semiconductor device incorporates a second field plate electrode below the second gate electrode in a trench, electrically connected to the gate pad, which reduces the electric field strength and facilitates detection of connection failures by measuring withstand voltage, especially in regions closer to the chip's end, thereby enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a vertical MOSFET structure is used with gate and source electrodes connected to metal layers on the upper surface, then the device achieves compact integration and high power conversion efficiency, but electrical connection failures between the gate pad and gate electrode cannot be reliably detected before packaging
Solution Approach 1:
The field plate electrode is electrically connected to the gate pad in advance through a conductor layer formed during the manufacturing process. This preliminary connection allows detection of gate pad connection failures before packaging by measuring withstand voltage, enabling early identification and removal of defective devices from production batches.
Solution Approach 2:
The field plate electrode serves as an intermediary element between the gate pad and the gate electrode. By providing this intermediate connection point, the structure enables indirect electrical connection and facilitates measurement of connection integrity without requiring direct access to the gate electrode, thus solving the detection problem in packaged devices.
2Area of stationary object
If the chip size is reduced to improve integration density, then manufacturing cost decreases and productivity increases, but connection failures near the chip periphery become more likely and harder to detect
Solution Approach 1:
The field plate electrode extends in the vertical dimension (depth direction) from the upper surface toward the lower surface of the chip. This vertical extension allows the electrode to reach deeper into the device structure, enabling detection of connection failures that may occur at various depths and positions, including peripheral regions, without increasing the horizontal chip footprint.
Solution Approach 2:
The conductor layer connecting the field plate electrode to the gate pad is formed during the manufacturing process before packaging. This preliminary formation of the detection path enables early identification of peripheral connection failures, allowing defective chips to be sorted out before they are packaged and shipped, thus maintaining high reliability despite reduced chip size.
3Reliability
If additional detection structures are added to the MOSFET, then connection failure detection capability improves, but device complexity and manufacturing steps increase
Solution Approach 1:
The field plate electrode performs multiple functions: it serves as an electrical connection element in the MOSFET operation and simultaneously acts as a detection probe for connection failure testing. The conductor layer connecting it to the gate pad also serves dual purposes of electrical connection and test signal transmission. This multi-functionality avoids adding separate dedicated detection structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The detection function is merged with the existing field plate electrode and gate pad connection structure. Instead of adding a separate detection electrode or test structure, the invention utilizes the field plate electrode's existing electrical connection to the gate pad, combining the operational and detection functions into a unified structure that minimizes additional complexity.
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 allows for easier identification of connection failures and improves the reliability of the semiconductor device by ensuring a lower likelihood of electrical connection failures affecting the MOSFET's performance, thus maintaining high withstand voltage and reducing manufacturing defects.
Implementation Method 1
the second field plate electrode configured to face the drift layer via a fourth insulating film
Data Source
AI summary
A semiconductor device includes: a first semiconductor layer of first conductivity type; a second semiconductor layer of first conductivity type provided on the first semiconductor layer and having a first region and a second region; a first semiconductor region of second conductivity type provided on the first region; a second semiconductor region of first conductivity type provided on the first semiconductor region; a second electrode provided in a first trench reaching the first region from above the first semiconductor region, the second electrode facing the first semiconductor region via a first insulating film, the second electrode being electrically connected to a first electrode provided above the first semiconductor layer; a fourth electrode provided below the second electrode in the first trench, the fourth electrode facing the first region via a second insulating film, the fourth electrode being electrically connected to a third electrode provided on the second semiconductor region and electrically connected to the second semiconductor region; a third semiconductor region of second conductivity type provided on the second region; a fourth semiconductor region of first conductivity type provided on the third semiconductor region; a fifth electrode provided in a second trench reaching the second region from above the third semiconductor region, the fifth electrode facing the third semiconductor region via a third insulating film, the fifth electrode being electrically connected to the first electrode; and a sixth electrode provided below the fifth electrode in the second trench, the sixth electrode facing the second region via a fourth insulating film, the sixth electrode being electrically connected to the first electrode.