Thin-Film Lithium Niobate on Insulator (LNOI) wafers are engineered substrates for integrated photonic and electro-optic devices.
The platform consists of a single-crystal lithium niobate thin film bonded onto a buried oxide (SiO₂) layer, supported by a silicon or insulating handle wafer.
This structure enables strong optical confinement, reduced propagation loss, and high electro-optic efficiency, making it one of the most important material platforms for modern integrated photonics.
Thin-Film Lithium Niobate (TFLN) Concept
Thin-Film Lithium Niobate (TFLN) refers to a sub-micron LiNbO₃ crystalline layer designed for high-confinement optical waveguides and electro-optic modulation.
Compared with bulk lithium niobate, TFLN provides:
- Stronger optical field confinement
- Higher modulation efficiency
- Reduced device footprint
- Compatibility with silicon photonics integration
TFLN is implemented on LNOI wafers to enable wafer-scale photonic integration.
Wafer Architecture
| Layer | Chất liệu | Functional Role |
|---|---|---|
| Device Layer | LiNbO₃ Thin Film (TFLN) | Electro-optic modulation, nonlinear optics |
| Insulating Layer | SiO₂ (Buried Oxide) | Optical isolation and mode confinement |
| Handle Wafer | Si / Quartz / Sapphire | Mechanical support and process compatibility |
Các tính năng chính
Ultra-low optical propagation loss < 0.05 dB/cm at telecom wavelength (1550 nm)
High electro-optic coefficient (r₃₃ up to 90 pm/V)
Sub-micron waveguide compatibility for compact photonic integration
CMOS-compatible integration with silicon and silicon nitride platforms
High thermal stability with Curie temperature ~1140°C
Multiple crystal orientations available: X-cut, Y-cut, Z-cut
Wafer sizes scalable from 3 inch to 8 inch
Thông số kỹ thuật
Wafer-Level Parameters
| Tham số | Thông số kỹ thuật |
|---|---|
| Wafer Diameter | 3″, 4″, 6″, 8″ |
| Độ dày | 525 ± 25 μm |
| Cung | ±50 μm |
| Warp | <50 μm |
| Local Thickness Variation (LTV) | <1.5 μm (5×5 mm², 95%) |
Thin-Film LiNbO₃ Layer
| Tham số | Thông số kỹ thuật |
|---|---|
| Chất liệu | Single-crystal LiNbO₃ |
| Thickness Range | 300 nm – 1000 nm |
| Orientation Accuracy | ±0.5° |
| Độ nhám bề mặt | Ra < 1 nm |
| Defect Criteria | No voids >1 mm |
Buried Oxide Layer
| Tham số | Thông số kỹ thuật |
|---|---|
| Chất liệu | SiO₂ |
| Độ dày | 100 nm – 2 μm (customizable) |
| Uniformity | ±5% |
Fabrication Technology
LNOI wafers are fabricated using semiconductor-compatible processes:
- Controlled ion implantation for crystal layer definition
- Wafer bonding onto insulating substrates
- Thermal annealing for crystal quality recovery
- Chemical Mechanical Polishing (CMP) for surface planarization
- Metrology-based inspection for optical and structural quality assurance
Application Fields
Integrated optical communication systems including high-speed modulators for 100G to 800G transmission
Quantum photonic systems for entangled photon generation and quantum information processing
Microwave photonics for RF signal processing and millimeter-wave photonic systems
Nonlinear optical devices including frequency conversion and optical frequency comb generation
Integrated optical sensing systems for biochemical and environmental monitoring
Performance Comparison
| Bất động sản | Bulk LiNbO₃ | LNOI Thin-Film Platform |
|---|---|---|
| Optical Loss | Cao hơn | <0.05 dB/cm |
| Device Footprint | Large | Sub-micron scale |
| Integration Capability | Số lượng có hạn | High-density photonic integration |
| CMOS Compatibility | Không | Đúng |
| Modulation Efficiency | Trung bình | High (Vπ ~ 1V achievable) |
Custom Engineering Options
Crystal orientation selectable among X-cut, Y-cut, and Z-cut configurations
Thin-film thickness engineered between 300 nm and 1000 nm
Buried oxide thickness adjustable for optical confinement tuning
Substrate options include silicon, quartz, and sapphire
Optional MgO doping for improved optical damage threshold
Quality Assurance and Metrology
Each wafer undergoes strict semiconductor-grade inspection:
Optical loss measurement at telecom wavelength bands
Atomic force microscopy for surface roughness evaluation
Infrared inspection for bonding interface integrity
Thickness and uniformity mapping across full wafer
Wafer flatness and stress distribution analysis
Engineering and Manufacturing Capability
ZMSH provides end-to-end LNOI wafer engineering solutions, including material design, wafer bonding process development, photonic device fabrication support, nanofabrication processes (EBL, IBE), and optical characterization services.
The production capability supports both R&D-scale prototyping and small-to-medium batch manufacturing, with stable 6-inch production and ongoing development of 8-inch LNOI platforms.
Câu hỏi thường gặp
1. What is Thin-Film Lithium Niobate used for
It is used in integrated photonics, optical communication, quantum photonics, and nonlinear optical devices.
2.What is the typical thickness of the lithium niobate thin film
The film thickness typically ranges from 300 nm to 1000 nm depending on device requirements.
3.What are the advantages of LNOI over bulk lithium niobate
LNOI enables lower optical loss, higher integration density, and compatibility with silicon photonics platforms.
4.Is LNOI compatible with silicon photonics
Yes, LNOI can be integrated with silicon and silicon nitride photonic platforms.
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