Through years of partnership with MEMS companies, YES understands the challenges of MEMS device manufacturers. YES offers established processes and proven tools to assist the industry with applications needed to be successful.
Take a closer look at our YES tools and the MEMS solutions they provide:
Surface Tension Modification – As devices are made smaller, static friction (stiction) becomes more significant. By modifying the surface tension with a class of fluorinated silanes, the operating life of moving parts in MEMS devices can be significantly lengthened. Conversely, if surfaces need to be bonded together, other silanes can be coated which enhance bonding strengths between unlike materials.
Getter Activation – Getters are used to scavenge unwanted gases in many applications. In MEMS devices, getters may be used to tie up excess moisture or hydrogen which may interfere with the long term operation of the device. Activating the getter material involves high temperature and high vacuum processing to ensure the material starts as moisture / hydrogen-free as possible. 400°C high vacuum 10-5 removes moisture/hydrogen gas from wafers and getters. Wafer and getter activation ensures no gas or moisture at the same time.
Wafer Dehydration – The moisture on the surface of wafers will cause unintended reactions with various deposition steps. These reactions result in unstable surface which degrade over time. Vacuum dehydration provides a clean stable starting surface resulting in superior films.
Metal Annealing – Annealing is a heat treatment where the microstructure of a material is altered, causing changes in its properties such as strength and hardness. In the semiconductor industry, silicon wafers are annealed so that dopant atoms (such as boron, phosphorus or arsenic), can be incorporated in substitutional positions into the crystal lattice, which drastically changes the electrical properties of the semiconducting material.
In the case of copper, adding an anneal step:
- Improves properties of the copper layer
- Increases grain size for faster polishing
- Provides better conductivity
- Reduces surface tension
- Minimizes electromigration
- Allows a consistent CMP rate across the wafer
Thermal treatment of Thin Film Resistors – Thin film resistors can change properties rapidly as they age unless they are properly thermally treated. The process stabilizes the crystal grain and ensures long term predictable behavior.
Photoresist strip and descum – In device fabrication, photoresist is used to transfer a pattern onto a substrate. After the pattern is created in the resist, a descum operation is performed to remove trace amounts of resist or other residues. Once a pattern is transferred, the remaining photoresist must be removed from the substrate before it can move to the next processing step. Plasma systems are effective for stripping thick layers of photoresist, as well as descumming, etching, and removing organics.