Schottky Diode Layout for Low Reverse Current and Better Heat Dissipation
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Solution Overview
Problem
Schottky diodes face limitations in low reverse current and heat dissipation due to their manufacturing processes, which result in high leakage current and size constraints.
Innovation Solution
The Schottky diode is designed with a horizontal configuration on a substrate, featuring a cathode and anode structure with heavily and lightly doped regions, and a backside metal film to reduce equivalent resistance, manufactured using the WLCSP process without a lead frame, eliminating conventional packaging steps like die attaching and wire bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packaging process (die attaching, wire bonding, encapsulant molding) is used, then the Schottky diode package is protected and manufactured, but heat dissipation capability is limited and overall size is increased
Solution Approach 1:
The patent extracts and removes the lead frame and encapsulant from the conventional packaging structure, directly exposing the diode chip. This eliminates the thermal barriers created by these components while maintaining essential protection through selective structural design.
Solution Approach 2:
The patent transitions from a vertical packaging structure to a horizontal planar configuration where the diode chip is mounted directly on the circuit board. This dimensional change eliminates the need for tall lead frames and enables superior thermal contact with the board.
2Reliability
If conventional packaging process (die attaching, wire bonding, encapsulant molding) is used, then the Schottky diode package is manufactured, but overall size is increased
Solution Approach 1:
The patent removes the lead frame and encapsulant components that contribute significantly to package volume. By eliminating these bulky elements, the overall package size is reduced while essential protection functions are maintained through alternative structural arrangements.
Solution Approach 2:
The patent adopts a horizontal planar layout instead of vertical stacking, allowing the diode chip to be mounted directly on the circuit board surface. This dimensional reconfiguration eliminates the height contributed by lead frames and encapsulants, achieving compact packaging.
3Object-generated harmful factors
If Schottky diode is designed with multiple p-type doped regions, then reverse current is limited, but manufacturing complexity increases
Solution Approach 1:
The patent divides the anode structure into multiple discrete p-type doped regions (P+ regions) separated by intervals. This segmentation creates multiple depletion regions that collectively limit reverse current while allowing each region to be formed using standard, well-established doping processes.
Solution Approach 2:
The patent modifies the doping parameters by creating regions with different doping concentrations (heavily doped P+ regions versus lightly doped N- regions). This parameter variation enables effective reverse current limitation through controlled depletion region formation without requiring fundamentally new manufacturing techniques.
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 design significantly reduces reverse currents and forward voltage while enhancing heat dissipation, allowing for a more compact and efficient Schottky diode with improved performance.
Implementation Method 1
a heavily doped n-type region diffusing from a surface of the epitaxy layer into the substrate; a lightly doped n-type region formed in the epitaxy layer and around the highly doped n-type region
Implementation Method 2
a plurality of p-type doped regions, each p-type doped region diffusing from the surface of the epitaxy layer into the substrate, wherein each adjacent two of the p-type doped regions P+ are separated by an interval
Implementation Method 3
a backside metal film formed on a back surface of the substrate
Implementation Method 4
enhancing heat dissipation
Data Source
AI summary
A Schottky diode includes a substrate with an epitaxy layer on which a cathode region and an anode region are defined. A cathode structure and an anode structure are formed in the cathode region and the anode region respectively and horizontally separated by a distance. The anode structure includes a plurality of p-type doped regions diffused from the epitaxy layer toward the substrate, with an interval is formed between adjacent two p-type doped regions. A backside metal film and a backside protection layer are sequentially formed on a back surface of the substrate. Since the manufacturing of the Schottky diode does not involve wire bonding and molding processes, the overall thickness of the Schottky diode is reduced and heat dissipation is improved. With the backside metal film on the back side of the substrate, an equivalent resistance and a forward voltage of the Schottky diode can be reduced.