Dry and Wet Etching are two popular processes that are being used for the production of patterned sapphire substrate. Having said that, it makes sense to understand the difference between the two so that you can determine which particular process suits best to your unique needs. So, I have prepared below some sort of comparison between the two processes.
Dry etching
– the most common method to etch sapphire substrate and is considered to be a very slow process with a low throughput rate;
– the time to etch a standard 2-inch wafer is between 30 and 60 minutes;
– experts say that it does not scale effectively; as wafer size increases, throughput of a dry etcher falls because fewer wafers fit inside the vacuum chamber. This results to the use of more expensive plasma etching tools to attain the same throughput as achieved using smaller wafers;
– dry etching rates range between 50nm and 200nm in a minute (an estimate by some experts);
– dry etching creates bright and efficient LEDs but the process takes it so slow and limited throughput.
Wet etching
– wet etching process provides the advantage of being extremely fast and it comes a lot cheaper than dry etching;
– it produces LEDs that are not quite as efficient and effective as the dry etching process, however it is very scalable;
– wet etching process provides a cost-saving advantage compared to dry etching;
– in wet etching, a polishing touch-up work is done on the wafers so that light extraction efficiency is increased.
Sample of equipment utilized in sapphire etching process:
The Accubath Xe-Series — designed to perform a wet etching process; this etching bath equipment has been proven to be a great help for semiconductor manufacturers as it helps improve the processes that were previously thought to be too slow due to temperature limitations. This equipment is developed by Imtec Acculine.
Hitachi High-tech Silicon Etch System — this equipment is used in dry etching based on an ECR(*1) plasma source, it is capable of generating a stable high density plasma at a very low pressure.
CDE-80N Chemical Dry Etching Equipment — used chemical dry etching process for thin film in a gaseous state semiconductor process. Damage-free etching process, through perfect separation of the etching unit and plasma generating unit, enables wide use in the damage removal process.
Each of the etching processes discussed above has its own advantages and disadvantages. But, just like any other processes, select the one you think can improve your bottom-line — profit.
Paul Drake writes a wide array of industry-related topics such as etching sapphire equipment. He leverages his years of work experience in a high tech industry in writing useful resources. To learn more about wet etching process, visit Imtec Acculine official website.