A Correlative Defect Analyzer Combining Glide Test with Atomic Force Microscope

We have developed a novel instrument combining a glide tester with an Atomic Force Microscope (AFM) for hard disk drive (HDD) media defect test and analysis. The sample stays on the same test spindle during both glide test and AFM imaging without losing the relevant coordinates. This enables an in situ evaluation with the high-resolution AFM of the defects detected by the glide test. The ability for the immediate follow-on AFM analysis solves the problem of relocating the defects quickly and accurately in the current workflow. The tool is furnished with other functions such as scribing, optical imaging, and head burnishing. Typical data generated from the tool are shown at the end of the paper. It is further demonstrated that novel experiments can be carried out on the platform by taking advantage of the correlative capabilities of the tool. 1. Introduction Media defect control has always been a critical part of the HDD manufacturing process. It has a direct effect on the manufacturing product yield which drives the bottom line of business. In the hard disk drive, high media defect level can also cause reliability problems resulting in unforeseen economic losses. Furthermore, defect-free media is an enabler for implementing new HDD technologies. On the other hand, in order to allow high areal density recording necessary for sustained market growth, the head disk spacing in HDD has been pushed down to an extremely small margin [1–3]. As a result, even defects with very small sizes are now becoming serious performance and reliability challenges. Defect failure analysis (DFA) which analyzes media defects on rejected disks from the production lines plays a central role in the defect process control as it finds the root causes and provides clues for corrective actions. The DFA is done separately from the line test, for example, the glide test. The normal procedure is to send a small portion of the line rejects to the DFA lab where the technicians try to relocate the defects manually, for example, with an optical microscope, before sending them off for examination with an analytical tool such as an AFM. As the criteria for the defects of interest become smaller, manual defect relocation becomes a bigger problem. There are often cases of missed defects when doing DFA or not finding the right ones within the contaminations generated during the handling after the line test, leading to long frustrating days with negative impacts on manufacturing progress. We have developed a tool which combines glide with AFM. We choose the glide test for its unique sensitivity