Integrated Design and Simulation of Semiconductor Devices in Atlas TCAD and Cadence Virtuoso

Note 1: This milestone involves use of Atlas TCAD software. If you do not possess the software, get in touch with the Module Creator to obtain it.

Note 2: This milestone is a computational and simulation-based study. It does not involve usage of any laboratory equipment. However, Familiarity with using Atlas TCAD software is mandatory to work on this milestone.

Aim: The initial milestone focuses on precisely specifying the physical dimensions and layout of the device within the Atlas TCAD environment. This involves utilizing Atlas TCAD tools to input and visualize the geometry. This ensures a foundational understanding for subsequent simulations. Also, at this stage the simulation begins.

Method: Follow the below steps.

1. Choose a semiconductor device you wish to work with (e.g., transistor, diode, etc.).
2. Launch Atlas TCAD. This is the platform where you will perform the device simulation.
3. Create a new project. This is where you will define the parameters and characteristics of your semiconductor device.
4. Define material properties of the device, as well as any doping profiles or impurities present.
5. Specify physical properties. Use the tools within Atlas TCAD to precisely specify the physical dimensions of your device. This includes parameters such as width, length, thickness, and any other relevant dimensions. Input these values into the simulation model.
6. Create the device layout. his involves defining the spatial arrangement of different components within the semiconductor device. For example, if you're simulating a transistor, you'll define the positions of the source, drain, and gate regions.
7. Visualise the geometry using the visualization tools provided by Atlas TCAD. This step is crucial for ensuring that the specified dimensions and layout match your design expectations.
8. Validate the input to ensure that the specified details are accurate
9. Save the project

Structure: In order to achieve this milestone, write a 1000 words article in the below format.

1. Introduction to semiconductor technology and the role of integrated circuits in modern devices
2. Existing limitations in device simulation and the need for this study
3. Introduction to Atlas TCAD as a simulation tool
4. Introduction to the chosen semiconductor device
5. Specifications and characteristics of the chosen semiconductor device
   • Device type
   • Material properties
   • Physical dimensions
   • Device layout
6. Process of specifying dimensions in Atlas TCAD (include screenshots/ diagrams wherever necessary)
7. Validation process (if any used)
8. Challenges encountered during the input specification and validation process
9. Summary

With this milestone, the simulation data is derived, and validation of the specified device parameters is completed.

Note 1: This milestone cannot be achieved unless the previous milestone ‘Define Device Geometry’ is completed. Obtain the simulation results of that milestone from the Module Creator in order to proceed with this milestone.

Note 2: Advanced level familiarity with Atlas TCAD software is necessary to work on this module.

Aim: In the previous milestone the device specifications were stated in Atlas TCAD software and visualisation was done. In this milestone, the aim is to set up optimized biasing conditions to ensure the optimal performance of the device to configure biasing parameters within the Atlas TCAD environment. The outcome will be a documented set of biasing conditions aimed at achieving optimal device behaviour.

Method: Follow the below steps.

1. Review the initial simulation results and verify them using preliminary or default biasing conditions. The default or preliminary bias conditions will depend upon manufacturer's recommendations, device type, nominal operating points and commonly used values. Identify areas where the device behavior can be improved or optimized.
2. Define optimization goals including maximizing current flow, minimizing power consumption, optimizing response time, or achieving a specific performance metric for the chosen device.
3. Identify critical performance parameters such as gate voltage, drain voltage, source voltage, or any other biasing conditions based on the device.
4. Setup parameter sweep analysis on Atlas TCAD to observe the impact of different biasing conditions on device performance.
5. Perform sensitivity analysis to identify which biasing parameters have the most significant impact on the chosen performance metrics.
6. Start an iterative optimization process, adjusting biasing conditions based on the insights gained from parameter sweep and sensitivity analyses.
7. Continuously monitor key performance metrics such as current-voltage characteristics, transconductance, and threshold voltage.
8. Ensure convergence by checking the convergence of your simulations under different biasing conditions.
9. Document the optimising biasing conditions by including specific values for each biasing parameter and any relevant simulation settings.
10. Conduct additional validation simulations using the optimized biasing conditions.

Structure: To achieve this milestone, write a 1000 words article in the below format.

1. Introduction to the findings of the previous milestone and aim of this milestone
2. Chosen optimisation parameters
3. Chosen critical performance parameters
4. Findings of the parameter sweep analysis (briefly explain the process you followed for performing this analysis and give relevant hyperlinks of the tutorial articles)
5. Findings of the sensitivity analysis (briefly explain the process you followed for performing this analysis and give relevant hyperlinks of the tutorial articles)
6. Performance of the simulation in different biasing conditions
7. Findings of additional validation simulations (explain which validation simulations you have used, how you performed them and the findings of these simulations)
8. Conclusion/ summary- sensitivity of the simulation to different environmental conditions (explain briefly which environmental conditions you have considered)

With this, the simulation performance is improved as we test it in different biasing conditions.

Note 1: This milestone cannot be achieved unless the previous milestone ‘Optimising biasing conditions’ is completed. Obtain the simulation results of that milestone from the Module Creator in order to proceed with this milestone.

Note 2: Advanced level familiarity with Atlas TCAD software is necessary to work on this module.

Note 3: This milestone involves incorporating advanced mathematical and physical models like CONMOB, FLDMOB, AUGER, IONIZ, & SELB into the Atlas TCAD framework. Therefore familiarity with such models is necessary.

Aim: After running the simulation and optimising it against biasing conditions, the aim of this milestone is to incorporate physics-based models to capture the intrinsic behaviour of the device. Aligning the simulation with physical principles governing device behaviour, advanced models are implemented in the Atlas TCAD framework. For instance, the BTBT (Band-to-Band Tunneling) model is commonly employed for simulating tunneling devices to facilitate an accurate representation of electron tunneling phenomena. On the other hand, the SRH (Shockley-Read-Hall) model finds application in the simulation of Schottky devices, which effectively captures recombination and trapping processes within the semiconductor material.

Method: follow the below process.

1. Identify and select the physics-driven models which you want to apply, like CONMOB, FLDMOB, SRH, FERMIDIRAC, BGN. Understand their equations.
2. Ensure that these models are compatible with Atlas TCAD
3. Implement the models in the Atlas TCAD software depending upon device type like tunnelling or Schottky devices.
4. Verify the implementation by comparing simulation results with experimental data or theoretical expectations.
5. Use test cases specifically designed to validate the chosen models.
6. Follow the optimisation and calibration steps.
   • Fine-tune model parameters to optimize their performance. Adjust parameters such as carrier lifetimes, energy levels, and other relevant factors to align the simulated behavior with expected physical characteristics.
   • Calibrate the models by comparing simulated results with experimental data. Adjust model parameters to achieve a close match between simulation and experimental outcomes.
7. Document all the equations and the findings.
8. Perform validation and sensitivity analysis by:
   • identifying accurate validation parameters like current-voltage characteristics, carrier concentrations.
   • Obtain experimental data for the semiconductor device under similar conditions.
   • Use statistical analysis techniques to quantitatively assess the agreement between simulation results and experimental data.
   • Test the device under different temperatures, biasing conditions, and other parameters to ensure the model's robustness.
9. Compare the results obtained with the physics-driven models to those from previous simulations without these models and highlight the improvements.

 

Structure: In order to achieve this milestone, write a 1000 words article in the below format.

• Introduction to the previous milestone and aim of this milestone
• Background of the semiconductor physics- Introduction to the physics-driven models and their relevance in capturing intrinsic device behaviour
• Review of existing literature on physics-driven models
• Background of the chosen physics-driven models, and the equations and principles behind these models
• Implementation methodology of these models in Atlas TCAD.
• Visualisation and figures of simulation results, comparisons, and model implementations.
• Process of application of validation and sensitivity analysis and their findings
• Conclusion/ summary- challenges faced in the application

 

Note 1: This milestone cannot be achieved unless the previous milestone ‘Implement Physics-Driven Models’ is completed. Obtain the simulation results of that milestone from the Module Creator in order to proceed with this milestone.

Note 2: Advanced level familiarity with Atlas TCAD software is necessary to work on this module.

Aim: This is the final milestone in Goal 1. So far in this module, we have run the simulation of the chosen semiconductor device and optimised it against biasing conditions using Atlas TCAD software. In this milestone, exhaustive process and device simulations will have to be performed to validate and refine the semiconductor device's performance. The goal is to validate the robustness and accuracy of the device under varying conditions such as temperature, voltage, and material parameters. This provides a comprehensive documentation of the simulation results and a detailed analysis.

Method: Follow the below steps.

1. Define temperature range choosing both low and high extremes. Then establish the baseline temperature.
2. Modify the simulation settings in Atlas TCAD
3. Set up a temperature sweep analysis, where the simulation is run multiple times with the temperature varying within the defined range.
4. Adjust material properties such as carrier mobility, bandgap, and thermal conductivity and adjust them based on temperature.
5. Execute the simulations for each temperature condition within the defined range.
6. Collect comprehensive data from each simulation run. Record device responses, performance metrics, and any other relevant output variables.
7. Compare the results.
8. Repeat this process for other parameters such as voltage.

Structure: To achieve this milestone write a 1000 words article in the below format.

• Introduction to the previous milestone and the goal of this milestone
• Purpose and findings of temperature sweep analysis
• Findings of different temperature settings
• Device responses to different simulations- discussion of results
• Findings of different voltage settings
• Device responses to different simulations- discussion of results
• Findings of different material parameter settings
• Device responses to different simulations- discussion of results
• Concluding paragraph

Note: This milestone is in continuation of the last milestone ‘Execute Comprehensive Process and Device Simulation’ under Goal 1. Therefore it cannot be achieved unless all the milestones in Goal 1 are completed.

Note 2: Advanced level familiarity with Atlas TCAD software and Verilog-A is necessary to work on this milestone.

Aim: To simulate the semiconductor device in Cadence Virtuoso, the initial step involves designing a robust Verilog-a model. This model serves as a bridge between TCAD and Cadence environments and translates the behaviour of the device into a format compatible with Cadence Virtuoso. The aim of this milestone is to develop the Verilog-a model.

Method: Follow the below steps.

• Introduction to the previous milestone
• Describe the key electrical characteristics and behaviors that need to be captured in the Verilog-A model.
• Define the requirements for the Verilog-A model. Identify the parameters and behaviors that the model needs to replicate to ensure compatibility with Atlas TCAD simulations.
• Set up the basic structure or skeleton of the Verilog-A model. This includes defining parameters, variables, and basic equations.
• Integrate physical models into the Verilog-A structure. You will find the models details in the milestone ‘Implement Physics-Driven Models’ under Goal 1.
• Extract key parameters from Atlas TCAD simulations and incorporate them into the Verilog-A model. Ensure that the model accurately represents the semiconductor device's characteristics under different conditions.
• Run the Verilog-A model in a simulation environment that supports Verilog-A, like CadenceAMS (analog/mixed-signal), and compare the results with the Atlas TCAD simulations. Validate that the Verilog-A model accurately replicates the TCAD results.
• Iterate on the Verilog-A model based on the validation results. Refine the model by adjusting parameters, equations, or incorporating additional physical effects to improve its accuracy.

Structure: To achieve this milestone, write a 1000 words article in the below format.

• Introduction to the previous milestone ‘Execute Comprehensive Process and Device Simulation’ and the aim of this milestone
• Assumptions of the Verilog-A model: key characteristics and behaviours that will be captured
• Requirements of the Verilog-A model
• Parameters, variables and basic equations of the Verilog-A model
• Findings of the Verilog-A model simulation
• Comparison to Atlas TCAD simulations
• Model adjustments (if any) to improve accuracy
• Concluding paragraph

 

Note: This milestone is in continuation of the last milestone ‘Execute Comprehensive Process and Device Simulation’ under Goal 1. Therefore it cannot be achieved unless all the milestones in Goal 1 are completed.

Note 2: Advanced level familiarity with Atlas TCAD software and Verilog-A is necessary to work on this milestone.

Purpose: The Cadence tools are employed to link and validate the Verilog-a model within the Virtuoso environment to ensure a seamless and error-free transition between simulation environments. The purpose of this milestone is to integrate the previously created Verilog-A model with Cadence Virtuoso.

Method: Follow the below steps.

1. Create a New Library in Virtuoso: Open the Virtuoso Schematic Editor in Cadence Virtuoso and create a new library to house the Verilog-A model and related symbols. Define the technology and parameters associated with the new library.
2. Import Verilog-A Model into Virtuoso: In Virtuoso Schematic Editor, create a symbol for the Verilog-A model. Then define ports on the symbol corresponding to the input and output ports of the Verilog-A model. Next, connect the ports on the symbol to represent the internal connections of the Verilog-A mode.
3. Assign parameters and connect ports based on the requirements of your simulation.
4. Configure and run the simulation setup: Configure the simulator settings to use the appropriate simulator for Verilog-A simulations and set simulation options, such as transient analysis, DC analysis, or other relevant configurations. Next, define the simulation parameters, attach the Verilog-A model and run simulation.

Structure: To achieve this milestone, write a 1000 words article in the below format.

• Introduction to the previous milestone and the goal of this milestone
• Process of integrating Verilog-A model into Cadence Virtuoso (explain the steps you followed in the simulation process).
• Findings and conclusion

 

Note: This milestone is in continuation of all the milestones in Goal 1. Therefore it cannot be achieved unless all the milestones in Goal 1 are completed.

Note 2: Advanced level familiarity with Atlas TCAD software and Verilog-A is necessary to work on this milestone.

Aim: This is the final milestone of this study. It focuses on ensuring the semiconductor device maintains good and consistent performance within Cadence Virtuoso. Through thorough testing and simulations, we aim to verify that the device behaves reliably under varying conditions. The objective is to establish a stable and dependable performance to guarantee the designed device meets the desired criteria for reliability and consistent operation.

Method: This milestone closely resembles the fourth milestone under Goal 1, i.e. ‘Execute Comprehensive Process and Device Simulation’. Follow the below steps.

• Define testing scenarios like variations in temperature, voltage, and other relevant parameters
• Create simulation settings in Cadence Virtuoso
• Conduct simulations with varying temperatures to evaluate the device's stability over a temperature range and note the findings
• Perform simulations with varying bias voltages to assess the device's stability under different biasing conditions and note the findings
• Implement parameter sweep analyses to explore the effects of variations in material properties and other parameters
• Simulate dynamic operating conditions, such as transient responses and sudden changes in input signals.
• Perform Monte Carlo simulations to account for manufacturing variations and other uncertainties.
• Introduce reliability testing scenarios, such as long-duration simulations or accelerated lifetime testing and test the device’s reliability under extended periods
• Explore corner cases where the device might experience extreme or unusual conditions.
• Analyze potential failure modes and simulate scenarios that could lead to device failure.
• Establish a feedback loop where simulation results inform any necessary adjustments to the design or simulation setup.
• Use statistical methods to analyze the consistency of simulation results.
• Compare simulation results with the initially defined design specifications.
• Perform a final validation by repeating key simulations and ensuring consistent results.

Structure: In order to achieve this milestone, write a 1000 words article in the below format.

• Introduction to the overall study and findings so far.
• Purpose of this article
• Process of the final simulation and testing (explain the steps followed briefly, define all the parameters which were set)
• Findings of the reliability simulation
• Conclusion