Integrated Power Device Start-Up Structure Segmentation
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Solution Overview
Problem
The integration of a start-up function in smart power devices is challenging due to high production costs and the risk of device destruction from avalanche current, which occurs when the inhibition voltage of the IC control device is not sufficiently higher than that of the MOSFET power device, leading to variability in the fabrication process.
Innovation Solution
A semiconductor power device with an integrated start-up structure, where the MOSFET switch and power device share the same inhibition voltage, with an annular edge structure providing insulation of over 25V, allowing for the integration of both functions in a single chip, reducing production costs and silicon area, and enabling simultaneous fabrication using the same process flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a high-voltage IC control device is integrated within the power device, then the start-up function is integrated and efficiency is improved, but production costs increase due to the need for high-voltage epitaxial thickness and edge structure
Solution Approach 1:
The device is segmented into two distinct regions: a first region housing the start-up structure and a second region housing the power structure. This segmentation allows each region to be optimized independently, with the start-up structure using lower-voltage epitaxial thickness while the power structure uses appropriate high-voltage thickness, thereby reducing overall production costs while maintaining integration benefits
Solution Approach 2:
Different regions of the semiconductor body are assigned different electrical characteristics and epitaxial thicknesses according to their specific functional requirements. The start-up region uses thinner, lower-cost epitaxial layer while the power region uses thicker, high-voltage epitaxial layer, achieving local optimization that reduces total manufacturing cost while maintaining both functions
2Reliability
If the inhibition voltage of the IC device is made much higher than that of the MOSFET power device to prevent avalanche current destruction, then device reliability is improved, but production costs increase due to process variability requirements
Solution Approach 1:
By separating the start-up structure from the power structure into different regions with different epitaxial thicknesses, the invention eliminates the need for one structure to protect the other from avalanche current. Each structure operates independently within its own optimized region, removing the safety margin requirements that would otherwise be needed to handle process variability
Solution Approach 2:
The semiconductor body acts as an intermediary that physically and electrically separates the start-up structure from the power structure. This separation prevents harmful avalanche currents from affecting either structure, allowing each to be designed with optimal voltage ratings without requiring excessive voltage margins to account for process variability
3Reliability
If the IC control device is fabricated on high-voltage epitaxial thickness with edge structure, then the inhibition voltage requirement is met, but fabrication complexity and production costs increase
Solution Approach 1:
The invention applies the principle of local quality by providing high-voltage characteristics only in the second region where the power structure is located, while the first region containing the start-up structure uses simpler, lower-voltage epitaxial thickness without complex edge structures. This localized approach maintains necessary voltage capabilities where needed while reducing overall fabrication complexity
Solution Approach 2:
The semiconductor body is divided into regions with different structural complexities. The power structure region includes the necessary edge structure and high-voltage epitaxial thickness, while the start-up structure region uses a simplified structure with lower-voltage epitaxial thickness, thereby reducing overall device complexity and fabrication difficulty
Data Source
AI summary
An integrated power device includes a semiconductor body of a first conductivity type comprising a first region accommodating a start-up structure, and a second region accommodating a power structure. The two structures are separated from one another by an edge structure and are arranged in a mirror configuration with respect to a symmetry line of the edge structure. Both the start-up structure and the power structure are obtained using MOSFET devices. Both MOSFET devices are multi-drain MOSFET devices, having mesh regions, source regions and gate regions separated from one another. In addition, both MOSFET devices have drain regions delimited by columns that repeat periodically at a fixed distance. Between the two MOSFET devices there is an electrical insulation of at least 25 V.