There is a huge gap between being able to apply the basics of physics practically in the laboratory setting and the technical know-how needed in the industry. We would like to narrow down this gap so students could easily assimilate in the industry.
In the lab, we always try to assume ideas large-scale systems and if we encounter slight deviations, we account these to system imperfections within acceptable limits. In the various semiconductor industries where mass production prevails, they’re going for cheaper and smaller but maintain the same level of quality all throughout the production – slight deviations mean big business losses.
Nanotechnology is one of the most popular marketing terms lately. This refers to the technology on very small devices. If you can imagine your head to be as big as the Earth, objects in the nanoscale would be in the range of the size of a golf ball to the size of a car. In this age of information technology, readily accessible knowledge makes one very powerful. With nanotechnology, 4.5 million books could be stored in a hard drive as small as an average man’s wallet. Imagine that instead of trying to fit millions of real books in your pocket!
Everything is just getting smaller and smaller. At Hitachi Global Storage Technologies (HGST) they make these hard disk drives (or simply just “hard drives”) and equip them with devices called magnetic read/white heads that “writes” the information on magnetic material and retrieves the stores information again into something that you can read or process. For the magnetic read/write heads to be able to write on store a huge amount of info, they also have to be incredibly small. In fact, these devices have sub-nanometer features (less than one nanometer or up to 10 Angstroms).
For this project, we collaborated with HGST and engineers from TIP to (1) learn to measure these sub-nanometer features in the read/write heads; (2) detect and determine damage to these sub-nanometer features by using a non-destructive optical technique; and (3) detect the very soft acoustic emissions that this nanoscale device makes when it operates. All these were done using instruments that we have at the NIP and TIP. Now these objectives might seem easy to you but the fact that they re in a very very small scale makes it an incredibly difficult feat. Before we could even start working on the main objectives of the project, considerable time and effort were used to qualify the instruments and skills of the operators. Through repeated consultations with the HGST experts, we were able to achieve industry-level competency with the use of the instruments and carry on with the experiments.
To measure the sub-nanometer features on the read-heads, we used an instrument called the atomic force microscope (AFM). This instrument works by tracking how much a nano-sized tip is deflected when it approaches a surface. Since we are at the nanoscale, forces between materials are more pronounced. The tip works like small fingers trying to trace the shape of the surface of the read-heads. Through this, we were able to track changes in the dimensions of the read-heads as we mimic conditions for the device in operation.
On the surface of the read/write heads in an overcoat made from diamond-like carbon (DLC). DLC is a very hard material that protects the device from repeated use. However, after some time, depending on the conditions of use, this overcoat would eventually wear out. This damage on the surface of the read/write heads was detected using a non-destructive optical technique called Raman spectroscopy. This technique works on the principle that different materials scatter light differently, i.e., we won’t be able to see the signature Raman spectra for DLC in those regions were the overcoat has worn off. This analysis helps HGST engineers in determining how the device is damaged for different conditions of use of the hard drives.
Sounds from nanoscale devices in operation (acoustic emission) are so weak that a barely inaudible whisper seems like someone shouting over a megaphone next to it. Nevertheless, the sounds they make are important in determining if the device inside are working well without having to take it apart. Extremely sensitive acoustic emission sensors were used to listen to the characteristic sound of certain stages of operation of the device. Despite this, the resulting data still looks like noise but the engineers from TIP were able to use signal analysis to process the noisy data and acquire the characteristic frequencies for different device conditions.
Through this project, we were able to demonstrate a viable process to narrow the gap and complement the knowledge gained in the academe and that which is needed by the industry.
Written by: Dr. Arnel Salvador University of the Philippines Diliman Published by: Department of Science and Technology-Science and Technology Information Institute (DOST-STII)