The LEP500 Base Systems are all supplied with Intellemetrics’ powerful EtchDirector software suite preinstalled and ready for your use. The full EtchDirector screen looks like this.
There are multiple user selectable windows allowing display of the parameters you want to see. These include;
The first thing you want to know is ‘What will the signal as a function of etch depth look like for my wafer?”. Therefore EtchDirector includes a full modelling capability.
EtchDirector includes a set of extensive libraries of materials with n and k values.
Each library operates at a different wavelength, depending upon the monitoring wavelength of the system you are using. For example, the standard 670nm library comes with over 250 materials preinstalled.
Each library is editable so you can change values and add or delete as many materials as required.
User friendly interface to enter the wafer details such as material and thickness.
Double click on a library entry to enter the n and k values.
Rapidly enter multiple quantum well structures and colour code them for easy viewing.
Cut and paste functions to speed entry.
Select Thickness Units from Angstroms to nm to microns.
Save Structure File for later use.
From the Structure Window simply press the Create Model button.
Shows the Reflectance versus Etch Depth.
Shows turning points.
Select axis units (Angstroms, nm or microns)
Full range of zooming capabilities.
Save data to a range of formats (Intellemetrics’ own .mod format, CSV, bitmap or copy to clipboard)
The model shows you the signal variations you should expect to see during the etch process.
The EtchDirector software enables you to create a wide range of endpoint conditions to track the etch depth and etch rate, and to automatically stop at the desired end point. The end point algorithms can be tailored and combined to satisfy a wide range of processes. The various modes available include…..
This is the simplest mode and is ideal for etching of bulk layers, or single layers on a substrate. The user simply enters the refractive index of the layer being etched and the desired end etch depth. The system monitors the etch, tracks the etch depth and etch rate and stops the system at the end point.
Filtering, Hold Off, and Overetch conditions can all be entered.
In Model Mode the user loads a previously modelled structure file and enters the desired etch depth. The system then tracks the live signal and uses advanced algorithms to determine the instantaneous etch depth. The system will create an end point condition when it reaches the desired etch depth.
Filtering, Hold Off, and Overetch conditions can all be entered.
Kink Mode is a powerful algorithm that can either detect the ‘flat’ line’ at the end of an etch process (such as etching resist on quartz) or it can be used to detect the interface between different absorbing materials such as various metal layers.
One of its biggest advantages is that you don’t need to know the starting thickness of the material you are etching….its will detect the interface anyway.
The Anomaly Mode automatically detects a wide range of changes during an etch process. These changes could be a change in etch rate, a change in amplitude, a change in shape, or combinations of all three. In this manner it can be used to monitor layers whose thicknesses are not known beforehand or that can vary from wafer to wafer. It can detect the passing of interfaces between layers and be set up to count the passage of layers, stopping at the end of the third layer for instance.
This is an extremely powerful and flexible technique that will have a wide range of applications. The image shows a wafer with three different materials. The customer didn’t know the thickness of each layer before the run, but knew that they had to stop as soon as the third layer had been etched…and they needed it to run automatically through all three layers.
The Anomaly Detector was set up to detect the change in profile of the live signal and successfully endpointed at the end of each layer. The EtchDirector software allowed the etch process to continue at the end of layers 1 and 2 but sent a STOP signal to the etch chamber at the end of layer 3.
During the etch process EtchDirector shows whatever views you want to see. These can include a live chart of the varying reflectance as a function of time, the theoretical reflectance as a function of etch depth, the live camera image, etc. During the run the system can be configured for manual operation (ideal for R&D labs where an operator is present to stop the etch process at the desired point) or in an automatic way if the system is connected to the control system via the digital IO option.