Ga2O3 Schottky Diode Lead Frame Layout for Heat Dissipation

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Solution Overview

Problem

Semiconductor devices with substrates made of materials like Ga2O3 suffer from poor heat dissipation due to low thermal conductivity, affecting the operation of Schottky barrier diodes as heat generated in the epitaxial layer cannot be efficiently transferred to the lead frame.

Innovation Solution

A semiconductor device design where a Ga2O3-based semiconductor element is face-down mounted on a lead frame with a raised portion, featuring a conductive adhesive connection and a field plate portion to enhance heat dissipation and reduce breakdown voltage, with specific distances and configurations to optimize thermal conductivity and electrical connectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a Ga2O3-based semiconductor substrate is used, then the Schottky barrier diode can be formed with desired electrical characteristics, but heat dissipation becomes poor due to low thermal conductivity

Engineering Contradiction:
Improveelectrical characteristicsVSAvoidheat dissipation
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The lead frame is divided into a raised portion and a flat portion, creating distinct functional zones. The raised portion provides electrical connection while the flat portion provides thermal conduction path, segmenting the heat dissipation and electrical connection functions to resolve the contradiction between electrical performance and heat dissipation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The flat portion of the lead frame acts as an intermediary between the Ga2O3 substrate and the heat sink. It provides a dedicated thermal conduction path that mediates the heat transfer from the low thermal conductivity substrate to the heat dissipation structure, improving heat dissipation without affecting electrical characteristics

Inventive Principle:
Principle #24Intermediary (Mediator)

2Temperature

If the outer peripheral portion of the epitaxial layer is located directly above the flat portion, then heat dissipation is improved, but the distance requirement for breakdown voltage suppression must be maintained

Engineering Contradiction:
Improveheat dissipationVSAvoidbreakdown voltage
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

Different portions of the lead frame are given different properties: the raised portion is optimized for electrical connection and the flat portion is optimized for thermal conduction. The epitaxial layer is positioned to utilize both properties, with its outer peripheral portion above the flat portion for heat dissipation while maintaining adequate distance for breakdown voltage suppression

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The problem is solved by utilizing the vertical dimension and horizontal positioning simultaneously. The epitaxial layer is positioned in a specific horizontal location (above the flat portion) and at a specific vertical distance (≥3μm), using spatial arrangement in multiple dimensions to satisfy both heat dissipation and breakdown voltage requirements

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

The design effectively enhances heat dissipation from the semiconductor device to the lead frame, improving operational efficiency and suppressing breakdown voltage decreases, thereby addressing the heat dissipation challenges in Ga2O3-based semiconductor devices.

Implementation Method 1

heat generated in the epitaxial layer during operation of the Schottky barrier diode cannot be efficiently transferred to the lead frame

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

heat generated in the epitaxial layer during operation of the Schottky barrier diode

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4084064B1Semiconductor device
Publication Date: 2024.12.04 TAMURA KK
  • EP4084064B1 patent drawingFigure 1A~1B
  • EP4084064B1 patent drawingFigure 2A~2B
  • EP4084064B1 patent drawingFigure 3

AI summary

Provided is a semiconductor device that has, mounted on a lead frame, a vertical semiconductor element which uses a Ga2O3-based semiconductor as the material of a substrate and epitaxial layer, the semiconductor device being capable of effectively releasing heat from the semiconductor device to the lead frame. As one embodiment, a semiconductor device 1 is provided which comprises: a lead frame 20 that has a projection 200 on the surface; and an SBD 10 that is mounted face down on the lead frame 20 and includes a substrate 11 which is made of a Ga2O3-based semiconductor, an epitaxial layer 12 which is stacked on the substrate 11 and made of the Ga2O3-based semiconductor, a cathode electrode 13 which is connected to the substrate 11, and an anode electrode 14 which is connected to the epitaxial layer 12 and has a field plate part 140 on an outer peripheral part. The SBD 10 is fixed on the projection 200, and an outer peripheral part 120 of the epitaxial layer 12 is located right above a flat part 201 of the lead frame 20.