TECHNOLOGY
GaN Power Semiconductors
TECHNOLOGY
GaN epitaxial wafer process challenges: Difficulties in commercializing same-type, large-diameter
GaN growth substrate wafers with high-cost efficiency
| (Legacy)growth substrate wafers | GaN | Sapphire | Si | SiC |
|---|---|---|---|---|
| Homo material growth substrate | Hetero material growth substrate |
|||
| GaN Epitaxy (Optical semiconductor, Power semiconductors) film disposition |
 |
 |
 |
 |
| Lattice constant difference (Δα) from GaN material | 0% | 13 | 17 | -3.5 |
| Thermal expansion coefficient difference (Δα) from GaN material | 0% | -34 | 55 | 25 |
| Lattice constant difference (Δα) from AIN material | 2.5% | 13 | 19 | 1 |
| Crystal defect density | 10³~10⁵/㎠ | middle 10⁷ | low 10¹⁰ | middle 10⁸ |
| Thermal conductivity | Fair | Bad | Good | Very good |
| Operational quality (reliability) | Very good | Fair | Very Bad | Bad |
| Substrate price | Very high | Fair | Low | High |
| Maximum substrate diameter | 4 inch | 8 inch | 12 inch | 8 inch |
Thermal-mechanical stress
induced crystal defects
Performance, quality, reliability degradation
GaN epitaxial wafers used as the core material for high-power amplification devices (such as HEMT), which are the core components of
5G&5G+ communication modules. These modules aim to achieve ultra-high speed, ultra-low latency and seamless connectivity in wireless communications.
Typically, GaN epitaxial wafers are produced by depositing films on electrically insulating silicon carbide (SI-SiC) growth substrates
with excellent thermal conductivity properties. This choice significantly affects the reliability, lifetime and quality of the modules.
The significant heat generated by power amplifiers during operation requires a solution with a high heat release rate.
A solution that has recently been proposed worldwide and gained global attention is to reduce the thickness without affecting the quality of the GaN epitaxy.
WaveLord, Inc. has also developed a 0.35 μmGaN epitaxial wafer.
The thickness of legacy systems
is on the order of 2 ㎛.
| Features | Applications | |
|---|---|---|
| SiC WES™ | High performance, high heat dissipation horizontal transistor support | Specialized for RF devices |
| Si WES™ | High-cost efficiency, horizontal transistor support |
RF and switching (<1,200V) devices |
| AIN WES™ | High-cost efficiency, Vertical transistor support |
Specialized for switching devices (≥2,000V) |
| (Legacy)growth substrate wafers | GaN | Sapphire | Si | SiC | WES™ |
|---|---|---|---|---|---|
| Homo material growth substrate | Hetero material growth substrate | ||||
| GaN Epitaxy ( Optical semiconductor, compound power semiconductors) film disposition |
|
|
|
|
 |
| Lattice constant difference (Δα) from GaN material | 0% | 13 | 17 | -3.5 | 0 |
| Thermal expansion coefficient difference (Δα) from GaN material | 0% | -34 | 55 | 25 | 0 or relaxation |
| Lattice constant difference (Δα) from AIN material | 2.5% | 13 | 19 | 1 | 0 or relaxation |
| Crystal defect density | 10³~10⁵/㎠ | middle 10⁷ | low 10¹⁰ | middle 10⁸ | 10⁶~10⁷ |
| Thermal conductivity | Fair | Bad | Good | Very good | Good |
| Operational quality (reliability) | Very good | Fair | Very Bad | Bad | Very good |
| Substrate price | Very high | Fair | Low | High | Fair |
| Maximum substrate diameter | 4 inch | 8 inch | 12 inch | 8 inch | 8 inch |
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