Simulation of CMOS Fabrication Processes for Double-Insulating Silicon-on-Diamond MOSFET
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-04-01 |
| Journal | Journal of Association of Electrical and Electronics Engineers |
| Authors | Hossein Eskandari, Arash Daghighi, Esmaeil Shafaghat |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Double-Layer Silicon-on-Diamond (DL-SOD) Transistors
Section titled âTechnical Documentation & Analysis: Double-Layer Silicon-on-Diamond (DL-SOD) TransistorsâThis document analyzes the research paper âSimulation of CMOS Fabrication Processes for Double-Layer Diamond-on-Silicon Transistorâ to provide technical specifications and align the material requirements with 6CCVDâs advanced MPCVD diamond capabilities.
Executive Summary
Section titled âExecutive SummaryâThe research successfully simulated and validated the fabrication processes for a high-performance Double-Layer Silicon-on-Diamond (DL-SOD) CMOS transistor, demonstrating significant advantages over traditional Silicon-on-Insulator (SOI) technology.
- Core Innovation: Utilization of a dual-insulator stack: MPCVD Diamond (Layer 1) for superior thermal management and Silicon Dioxide (SiO2) (Layer 2) for precise gate control.
- Thermal Management: Diamondâs ultra-high thermal conductivity (2000-2400 W/m·K) effectively mitigates self-heating effects, enabling higher power and frequency operation.
- High-Frequency Performance: The simulated 22 nm device achieved an exceptional Unity Gain Cutoff Frequency (fT) of 370 GHz.
- Electrical Characteristics: Demonstrated excellent transistor behavior, including a low Threshold Voltage (Vth) of 0.225 V and an On-Current density of 0.045 mA/”m.
- Material Requirements: The structure demands high-purity, thin-film diamond wafers suitable for subsequent CMOS processing (e.g., ion implantation, high-temperature deposition).
- 6CCVD Value Proposition: 6CCVD specializes in providing the necessary high-quality Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) substrates required to replicate and scale this advanced DL-SOD architecture.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the simulation results and material properties cited in the research.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Technology Node Size | 22 | nm | CMOS standard process used for simulation |
| Threshold Voltage (Vth) | 0.225 | V | Extracted electrical characteristic |
| On-Current Density (Ion) | 0.045 | mA/”m | Current density at VGS = 1 V |
| Unity Gain Cutoff Frequency (fT) | 370 | GHz | Key high-frequency performance metric |
| Maximum Stable Operating Frequency | 18 | GHz | Frequency at which current gain is stable |
| Diamond Thermal Conductivity (k) | 2000 - 2400 | W/m·K | Superior heat spreading capability |
| Diamond Bandgap (Eg) | 5.5 | eV | Ultra-wide bandgap insulator property |
| Diamond Critical Electric Field (Ec) | > 8 | MV/cm | High dielectric strength |
| Si3N4 Layer Thickness | 0.4 | nm | Ultra-thin layer for interface control |
Key Methodologies
Section titled âKey MethodologiesâThe DL-SOD transistor was fabricated using standard CMOS processes adapted for the dual-insulator stack, focusing on thin-film deposition and precise patterning.
- Substrate Preparation: Selection and doping of a Monocrystalline Silicon wafer (P-type) to serve as the base substrate.
- Diamond Deposition (Insulator Layer 1): MPCVD deposition of a high-quality Diamond film onto the silicon substrate, acting as the primary buried oxide and heat spreader (Figure 2).
- Dielectric Layer 2 Deposition: Sequential deposition of an ultra-thin Silicon Nitride (Si3N4) layer (0.4 nm) followed by Silicon Dioxide (SiO2) onto the Diamond film (Figures 3 & 4).
- Gate Oxide Patterning: Photolithography and etching processes used to define the SiO2 layer geometry.
- Active Region Doping: Light Boron ion implantation and thermal diffusion to define the P-type transistor body (Figure 9).
- Source/Drain Formation: Heavy Arsenic ion implantation and thermal diffusion to create the N-type Source and Drain regions, extending through the silicon layer to the Diamond interface (Figures 10 & 11).
- Gate Stack Formation: Sequential deposition of Gate Oxide (SiO2) and Polysilicon (Poly-Si), followed by masking and etching to define the 22 nm gate length (Figures 12-16).
- Metalization: Aluminum (Al) deposition and patterning to form the final Source, Drain, and Gate contacts (Figure 17).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful implementation of the DL-SOD architecture hinges on the quality and dimensional precision of the buried diamond layer. 6CCVD is uniquely positioned to supply the necessary MPCVD diamond materials and processing services required for this advanced research and development.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this high-performance DL-SOD research, engineers require diamond materials optimized for thermal and electrical isolation:
- Optical Grade SCD Wafers: Recommended for the highest performance devices. SCD offers the lowest defect density, ensuring maximum dielectric strength (Ec > 8 MV/cm) and superior thermal conductivity, which is critical for achieving the 370 GHz cutoff frequency.
- High Purity PCD Plates: Suitable for cost-effective scaling or larger area devices. 6CCVD offers high-quality PCD with thermal conductivity approaching that of SCD, ideal for heat spreading applications.
- Substrate Options: 6CCVD can supply the diamond film deposited directly onto silicon substrates, simplifying the initial integration step described in the paper.
Customization Potential
Section titled âCustomization PotentialâThe DL-SOD structure requires precise control over layer thickness and interface quality. 6CCVDâs capabilities directly address these needs:
| Requirement | 6CCVD Capability | Benefit to Researcher |
|---|---|---|
| Custom Dimensions | Plates/wafers available up to 125 mm (PCD) and large-area SCD. | Supports scaling from research prototypes to inch-size wafer processing for commercial viability. |
| Precise Thickness Control | SCD and PCD films available from 0.1 ”m to 500 ”m. | Allows researchers to fine-tune the buried oxide thickness, a critical parameter for optimizing short-channel effects and Vth control. |
| Interface Quality | Ultra-smooth Polishing (Ra < 1 nm for SCD, < 5 nm for inch-size PCD). | Ensures the ultra-smooth interface required for subsequent thin-film deposition (SiO2, Si3N4) and high carrier mobility in the overlying silicon layer. |
| Custom Metalization | In-house deposition of Au, Pt, Pd, Ti, W, and Cu. | Enables the precise formation of Source, Drain, and Gate contacts (e.g., Ti/Pt/Au stacks) necessary for low-resistance ohmic contacts in the final device structure. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in the material science of MPCVD diamond for high-power and high-frequency electronics. We can assist with:
- Material Selection: Advising on the optimal diamond grade (SCD vs. PCD) and thickness for similar Silicon-on-Diamond (SOD) Transistor projects.
- Interface Engineering: Consulting on surface termination and preparation techniques to ensure robust bonding and minimal defect formation at the Si/Diamond interface.
- Thermal Modeling: Providing material data and support for thermal simulation of diamond-based heat spreaders in high-density integrated circuits.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.