This article shows how to prepare samples and downsize wafers in the cleanroom, without compromising the cleanliness of the wafers or cleanroom. In this article, the LatticeAx 420 scribeless cleaving system is used for cleaving, followed by measuring the particle contribution of the LatticeAx cleaving process.
Most often, users of nanofabrication facilities have to prepare multiple samples from a piece of wafer or single wafer for parallel processing and other kinds of analysis and experiments. Downsizing wafers into coupons not only saves cost (reduced lost wafer material) but also shortens the process development time with respect to running a single experiment on an entire wafer. Since it is impractical for wafers to leave the cleanroom, samples are prepared in the cleanroom itself by cleaving or dicing saw. However, a major problem is that while cleaving is a dry process and also known to be the least destructive technique, it creates particles which can contaminate both the cleanroom and the sample.
The cleaving process tends to create particulate contamination. This process is traditionally carried out by scribing the wafer surface with a diamond scribe and then breaking the wafer by hand or using a pin or ruler for leverage. Therefore, a process must be developed to prepare samples in the cleanroom that does not compromise cleanliness. If an effective sample preparation technique is developed for the cleanroom, the risk that wafers will be lost, contaminated, or broken if removed is completely eliminated.
In association with leading nanofabs, LatticeGear has established that cleaving can be “cleaned” by employing the LatticeAx microline indent1 and cleave system.
Here is what the manager of a national nanofabrication facility said:
…Our needs for the 420 (LatticeAx) were based on the high number of users downsizing wafers (cleaving small pieces of wafer by hand) while in the fab, before moving samples to major process tools and or wet chemistry. Although we have many policies in place against doing this, they are difficult to enforce. Our costs to keep and maintain cleanliness are high and the only way to drive a change was to offer the user a way to cleanly cleave their wafers in the fab. We implemented a solution and they were glad to use it. Since acquiring the LatticeAx 420, we notice a significant reduction in particulate contamination, as most users have shifted to cleaving with this tool, so clearly there was a real need for this tool. Many users make multiple pieces from a single or partial wafer, so repetitive cleaving is also quite common)…
1Microline indent is a scribless process unique to LatticeGear and the LatticeAx Cleaving System
Figure 1. LatticeAx 420 Cleaving System on 18” (46 cm) cleaving mat.
Figure 3. Particle count comparison for 0.3-micron size, before and after wafer cleaving, points 1-3.
Read about the challenges to maintaining cleanliness in the nanofab, the advantages to “clean” dry wafer downsizing with the LatticeAx and view the entire particle count data in the full article.
Click Here to Read the Full Article
This information has been sourced, reviewed and adapted from materials provided by LatticeGear.
For more information on this source, please visit LatticeGear.