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;
- it does not scale effectively. As a wafer size increases, throughput of a dry etcher falls as fewer wafers fit inside the vacuum chamber. And because of that, more expensive plasma etching tools are needed to achieve the same throughput as achieved by smaller wafers;
- the dry etching rates range between 50nm and 200nm per minute;
- 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;
- it provides a considerable cost saving than the dry etching;
- in a wet etching process, the etcher needs to perform a polishing touch-up on the wafers to improve the light extraction efficiency.
Sample of equipment utilized in sapphire etching process:
The Accubath Xe-Series -- an etching bath equipment from Imtec Acculine, was designed with Sapphire etching in mind but we know there are other processes that will benefit from the increased chemical reactivity that higher temperatures provide (300C). Processes that were previously thought to be too slow due to temperature limitations may now be practical because of innovations like this.
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, choose the one you think can improve your bottom-line -- net income.
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;
- it does not scale effectively. As a wafer size increases, throughput of a dry etcher falls as fewer wafers fit inside the vacuum chamber. And because of that, more expensive plasma etching tools are needed to achieve the same throughput as achieved by smaller wafers;
- the dry etching rates range between 50nm and 200nm per minute;
- 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;
- it provides a considerable cost saving than the dry etching;
- in a wet etching process, the etcher needs to perform a polishing touch-up on the wafers to improve the light extraction efficiency.
Sample of equipment utilized in sapphire etching process:
The Accubath Xe-Series -- an etching bath equipment from Imtec Acculine, was designed with Sapphire etching in mind but we know there are other processes that will benefit from the increased chemical reactivity that higher temperatures provide (300C). Processes that were previously thought to be too slow due to temperature limitations may now be practical because of innovations like this.
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, choose the one you think can improve your bottom-line -- net income.
About the Author:
Paul Drake writes various 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.
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