Every software package contains a full set of examples suitable for that version and are installed with the software. If you see examples here that are not in your installation you should consider updating to a later version of the software. These examples can be used by beginners and advanced users for product evaluation, teaching purposes, and self-training.
Required Modules
Victory Process
- 3D Structure Editor
- 3D Diffusion & Implantation
Victory Mesh
- 3D Meshing
Victory Device
- 3D Simulator
- 3D Optical
This example demonstrates solutions to some of the particular 3D process and device issues when simulating a 3D image sensor cell. The first issue with a number of designs is the very high implantation energies required to isolate the active region of the image sensor.
The device simulation is in three parts. Firstly, the threshold voltage of the two pass transistors is simulated. Then a dark transient is simulated to find the dark current recovery time, which sets the low light sensitivity limit of the image sensor, i.e. the maximum useable light integration time. Finally, a simulation is done illuminating the device with a typical average light intensity of 0.01 Watts/cm2 with a standard solar AM 1.5 spectrum, which for this sensor, would require an integration time of approximately 0.0008 for a 50% exposure level. The illumination intensity and exposure integration time can both be adjusted by changing these two variable quantities at the set statement lines, near the top of the input file for the final device simulation.
The threshold voltage of the pass transistors is deliberately high to ensure that charge leakage in their off state is minimized. Since the pass transistors have a common floating electrode without an ohmic contact, the threshold voltage is plotted using the electron concentration under the gates. The electron concentrations are measured using probe statements, which probe the silicon surface under the gates. In this example, the probe quantities have been called “cg_conc ” and “ng_conc ” .
For the transient simulations, the output voltage of the cell can be monitored by plotting the probe quantity called fd_potential. Another interesting quantity also extracted using the probe statement is the electron concentration in the active image sensor region. This image sensor electron concentration is called “cis_conc ” in this example.
Images
