Multi-die DC-DC Buck Converter with Integrated Schottky Diode and MOSFET
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Solution Overview
Problem
Existing multi-die packages for switching power supplies and DC-DC converters are bulky due to the need for isolated die pads and bond wires, leading to increased size, cost, and reduced efficiency due to parasitic capacitance and inductance.
Innovation Solution
A compact multi-die semiconductor package design where the Schottky diode and vertical MOSFET are co-packaged atop a single die pad, eliminating the need for bond wires and using custom die configurations to minimize inductance and maximize heat sinking, with the power regulating controller attached via insulating or conductive die bonding materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If isolated die pads are used for Schottky diode and vertical MOSFET, then device mounting is simplified, but package size increases and parasitic inductance increases
Solution Approach 1:
The patent merges the Schottky diode and vertical MOSFET mounting onto a single shared die pad, eliminating the need for isolated die pads. This integration reduces the overall package size while maintaining ease of manufacture through standardized mounting procedures.
Solution Approach 2:
The patent implements a nested configuration where the Schottky diode is positioned adjacent to and electrically connected with the vertical MOSFET on the same die pad, creating a compact integrated structure that minimizes space while preserving manufacturing simplicity.
2Reliability
If bond wires are used to connect Schottky diode to ground and MOSFET source to inductor, then electrical connections are established, but parasitic inductance increases and efficiency decreases
Solution Approach 1:
The patent extracts and eliminates the bond wire connections by directly integrating the Schottky diode and vertical MOSFET on the same die pad, allowing electrical connections to be made through the substrate itself, thereby removing parasitic inductance and improving power conversion efficiency.
3Ease of manufacture
If standard lead frames are used, then manufacturing cost is reduced, but package size and parasitic inductance increase
Solution Approach 1:
The patent combines multiple device functions onto a single die pad structure that can be accommodated by standard lead frames, maintaining cost-effectiveness while reducing package size through integrated device placement.
4Reliability
If multiple isolated die pads are used, then device isolation is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the mounting structures for the Schottky diode and vertical MOSFET into a single integrated die pad configuration, reducing packaging complexity while maintaining adequate electrical isolation through strategic device placement and substrate design.
Data Source
AI summary
A DC-DC buck converter in multi-die package is proposed having an output inductor, a low-side Schottky diode and a high-side vertical MOSFET controlled by a power regulating controller (PRC). The multi-die package includes a first die pad with the Schottky diode placed there on side by side with the vertical MOSFET. The PRC die is attached atop the first die pad via an insulating die bond. Alternatively, the first die pad is grounded. The vertical MOSFET is a top drain N-channel FET, the substrate of Schottky diode die is its anode. The Schottky diode and the vertical MOSFET are stacked atop the first die pad. The PRC is attached atop the first die pad via a conductive die bond. The Schottky diode die can be supplied in a flip-chip configuration with cathode being its substrate. Alternatively, the Schottky diode is supplied with anode being its substrate without the flip-chip configuration.