We all know, silicon wafers are available in various sizes and specifications. Not only this, Silicon wafers are also available in different grades which decides the quality of the wafer, which is an important parameter to be considered in semiconductor device fabrication and research & development. In this article, we want to give brief insight into different grades of Silicon wafer available in market and their applications.
Silicon wafer is available in three quality deciding grades namely: Prime, Test and Dummy Grade. So lets begin with each grade one by one.
Prime grade wafers are the highest quality wafers. Quality is not just in terms of material purity but excellent polishing and negligible deviation from specifications. These wafers are also known as Device quality wafers. Price of Prime grade wafers is more in comparison to other lower grades, as these wafers are selected through strict quality control procedures. Prime grade Si wafers due to their excellent quality are used in semiconductor device fabrication industry and in Research & development, where slight variation in specifications may lead to dubious results and repeatability in outcomes may not be achieved.
As the name suggests, test grade silicon wafers are not used in direct production line in device industry but rather used in testing the process of device fabrication. Test grade wafers are very similar to prime grade wafers but they do not pass through any strict quality control for specification check. We can say, when prime grade wafers are selected from a wafer lot through quality control, the wafers that remain are test wafers. So the test wafers may have variation in their specifications, therefore are not used in device fabrication and are also not suitable in research application where slight variation may give confusing outcomes. Price of test wafers is less than prime wafers.
During the production of Silicon wafers, the wafer production line must be tested to check if desired specifications are produced or not. And during this testing and trial process the silicon wafers that are produced are catagorized as Dummy grade wafers. They are the cheapest grade of wafers available with no quality control and may have huge variation from specifications as they are produced during test and trial process. These wafers are not meant to be used out side the production line of Si wafers. But still, they are used in applications where requirement is just Silicon wafer and specification control is not required.
We at Vritra Technologies, only supply Prime grade Silicon wafers. As we are dedicated to serve research and Industrial community, where prime grade silicon wafer is the only suitable product. Still if you want to purchase lower grades, this has to be clearly mentioned in your requirement.