GaN HEMT and Diode Integration on Si Substrate
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Solution Overview
Problem
Power conversion devices face challenges in miniaturization and efficiency due to the need for separate semiconductor chips for transistors and diodes, leading to increased cost and power loss, especially when using IGBTs or wide band-gap semiconductors like SiC, which struggle to integrate both components on the same chip.
Innovation Solution
A semiconductor device integrates a high electron mobility transistor (HEMT) and a diode on the same chip, with the HEMT using a GaN channel layer and a pn junction diode on a Si substrate, where the diode's anode electrode is electrically connected to the anode region through a conductive material, allowing for a compact and efficient switching element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If IGBT transistor is used to obtain breakdown voltage performance of about 600 V, then breakdown voltage performance is improved, but two separate semiconductor chips are required increasing cost and device complexity
Solution Approach 1:
The patent merges the IGBT transistor and diode into a single semiconductor chip by forming both components on the same Si substrate. The IGBT is formed in a first region and the diode is formed in a second region of the same substrate, with shared structural elements like the drift layer and substrate, thereby reducing the number of chips from two to one while maintaining 600V breakdown performance.
2Strength
If IGBT is used for switching element, then breakdown voltage performance is improved, but switching loss is increased compared with power MOSFET
Solution Approach 1:
The patent optimizes the IGBT structure by forming a pinned diode with specific doping concentrations and depths. The pinned diode has a lightly doped drift layer with doping concentration of 1×10^15 to 1×10^17 atoms/cm³ and a heavily doped contact layer, creating a depletion region that reduces switching loss while maintaining high breakdown voltage capability.
3Strength
If IGBT is used for power conversion device, then breakdown voltage performance is improved, but power loss is increased due to high built-in potential of about 1 V
Solution Approach 1:
The patent reduces the built-in potential of the IGBT by optimizing the doping profile of the drift layer and emitter region. The drift layer is doped at 1×10^15 to 1×10^17 atoms/cm³ and the emitter is doped at 1×10^18 to 1×10^20 atoms/cm³, which lowers the contact potential difference and reduces conduction loss while maintaining high breakdown voltage through the optimized depletion region structure.
4Strength
If MOSFET with single crystal Si is configured to have high breakdown voltage of 200 V, then breakdown voltage is improved, but power loss is increased due to high on-resistance
Solution Approach 1:
The patent uses a composite structure combining Si substrate with optimized doping profiles and a pinned diode structure. The combination of lightly doped drift layer (1×10^15 to 1×10^17 atoms/cm³) and heavily doped contact layer creates a depletion region that provides high breakdown voltage while the heavily doped emitter (1×10^18 to 1×10^20 atoms/cm³) maintains low on-resistance, reducing power loss.
5Loss of energy
If wide band-gap semiconductor like SiC is used to reduce on-resistance, then on-resistance is reduced, but diode of pn junction cannot be formed due to high built-in potential of about 3 V
Solution Approach 1:
The patent uses Si as an intermediary substrate material that allows easy formation of pn junction diodes through standard doping processes. The Si substrate serves as the base material where both the IGBT and diode are formed, avoiding the need to use SiC for the diode region while still benefiting from the overall power conversion performance.
6Ease of manufacture
If Schottky barrier diode is formed in SiC semiconductor layer, then diode can be formed, but cost is increased due to complicated manufacturing method and increase in chip area
Solution Approach 1:
The patent combines the IGBT and diode formation processes into a single manufacturing flow on the same Si substrate. Both components are formed using standard Si processing techniques including doping, oxidation, and deposition, eliminating the need for separate SiC processing steps and reducing chip area compared to using Schottky diodes on SiC.
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 integration enables miniaturization of the switching element and improves power conversion efficiency by reducing on-resistance and power loss, while maintaining high breakdown voltage performance suitable for applications like hybrid automobile motor drives.
Implementation Method 1
a compound semiconductor layer 10 of a high electron mobility transistor (HEMT) is formed on a first main surface 20a of a semiconductor substrate 20 of a diode
Implementation Method 2
an anode electrode 26 of the diode is electrically connected to an anode region 23 via a conductive material embedded in a hole 25
Data Source
AI summary
In a semiconductor device in which a diode and a high electron mobility transistor are incorporated in the same semiconductor chip, a compound semiconductor layer of the high electron mobility transistor is formed on a main surface (first main surface) of a semiconductor substrate of the diode, and an anode electrode of the diode is electrically connected to an anode region via a conductive material embedded in a via hole (hole) reaching a p+ region which is the anode region of the main surface of the semiconductor substrate from a main surface of the compound semiconductor layer.