Applications
- Wire bond surface preparation
- Removing contaminants (flux) or sterilizing a surface
- Promoting adhesion between two surfaces
- Controlling surface tension to achieve a hydrophilic surface
- Increasing biocompatibility
- Improving polymer performance through cross-linking to decrease friction that wears out devices
Benefits
- Environmentally friendly–no wet chemical usage
- Five plasma mode selections
- Touch screen PLC control
- Safe for sensitive electronic devices
- Repeatable, uniform results
YES-G1000 and YES-G500 provide five plasma modes to give engineers flexibility over their cleaning processes. Power density and capability are the same in both machines; capacity is the only difference.
YES cleaning systems utilize a low plasma generation frequency (40 kHz) to reduce chamber and product heating sometimes caused by high frequency (13.56 MHz) systems. As a result, YES systems are ideal for cleaning even electronically sensitive devices. Plasma is generated between active trays and grounded trays or chamber walls. Laminar airflow through the chamber eliminates dead spots and enhances plasma uniformity.
YES plasma cleaning systems have five plasma modes:
Mild anisotropic modes
1. Electron Free/Downstream Mode: Used for cleaning sensitive electronic devices prior to wire bonding. Product is on a floating tray outside the plasma generation volume. Plasma passes through a grounded tray to the product, balancing the charged species to limit surface charge build up.
2. Active Mode: Used for etching and surface modification prior to bonding applications. Product is on a grounded tray inside the plasma generation area.
3. RIE Mode: The most aggressive plasma for surface modification applications. Product is on the active tray inside the plasma generation volume. The electrical field at the product’s surface increases ion collision energy.
Isotropic modes
4. Active Ion Trap: The most aggressive plasma for reactive processes. Product is on an active tray outside the plasma generation volume. Ion trap plasmas have high ion concentrations at low energy levels.
5. Downstream Ion Trap: Used for aggressive, electron-free cleaning. Product is on a grounded tray outside the plasma generation volume.
In semicondutor fabrication, after an IC chip is affixed to the ceramic substrate, it’s baked to cure the epoxy. But this process causes small amounts of contamination on top of the bond pads that can inhibit wire bonding. Plasma cleaning, or descumming, the surface to remove contaminants improves the wire bond.
In biomedical applications, plasma cleaning removes small amounts of contaminants as well as sterilizes substrates. Plasma cleaning increases biocompatibility and controls surface tension to achieve either a hydrophobic or hydrophilic surface.
Variable Frequency Matching (VFM)
The VFM power supply allows automatic adjustment-free processing. One of the advantages of 40kHz over 13.56 MHz is that the impedance matching only needs to be “in the neighborhood”. However, with longer process cycles or lighter processes gases, the window of best match can shift. The variable frequency will automatically compensate for any changes in the system (including load) to maintain optimal matching. The result is less reflected energy and more efficient coupling of the energy for ideal process conditions.
