Nitrogen in the semiconductor factory main use

nitrogen has a very high status in semiconductor factories, and can be said to be the largest amount of gas with the widest coverage process. It is like the blood in the factory, almost every production link is inseparable from it. The following is a clear explanation of its main uses.

The first use of protective gas to prevent oxidation

in the semiconductor manufacturing process, many materials are particularly afraid of oxygen. For example, when a silicon wafer is exposed to oxygen at high temperature, an oxide layer will be generated on the surface, which will directly destroy the performance of the chip.

Nitrogen is chemically very stable and hardly reacts with anything. Therefore, in those links that need to be isolated from oxygen, the factory will continue to flow nitrogen to keep oxygen and moisture out, creating a clean and safe environment for silicon wafers and other materials.

Whether it is the waiting time between manufacturing steps or high temperature annealing, nitrogen is silently used as a protective umbrella.

The second purpose is to purge and clean the dirt away.

there are a large number of equipment and pipelines in the semiconductor factory. Every time the process is switched or a process is completed, the gas, reaction by-products and various impurities from the previous round will remain inside the equipment. If it is not cleaned up, the next round of production will be contaminated.

At this time, the equipment and pipelines are purged with high-purity nitrogen, and all the remaining dirt is washed away. At the same time, nitrogen can also be used to clean the residual impurities on the surface of the wafer. For example, after acid and alkali treatment, the wafer will be clean with a blow of nitrogen.

This purging action is done during each process transition and is a key step in ensuring product quality consistency.

The third use of carrier gas to help other gases run errands

in a thin film deposition process such as chemical vapor deposition, it is necessary to send some special raw material gases into the reaction chamber. Nitrogen acts as a carrier gas here, just like a truck, transporting the raw material gas evenly to the place where it is needed.

Because nitrogen itself does not react with the raw material, it is particularly safe to use it as a carrier gas, which can ensure the uniform distribution of raw material gas and the quality of the deposited film is better.

In addition, in some processes, nitrogen can also be used as a dilution gas to reduce the concentration of active gases to prevent them from condensing into liquid in the pipeline and blocking the pipeline.

The fourth use to create a clean environment to maintain positive pressure

the clean workshop of the entire semiconductor factory needs to maintain a slightly higher air pressure than the outside, so that the dirty air outside cannot enter. And to maintain this positive pressure is nitrogen.

The factory will continue to fill the clean room with high-purity nitrogen, so that the indoor pressure is slightly higher than the outdoor. At the same time, in the interior of precision equipment such as lithography machines and etching machines, nitrogen is also used to maintain a super clean micro-environment, separating dust particles and harmful gases from the outside.

The fifth purpose of packaging and test link protection

after the chip is finished, it should be packaged. If it is exposed to oxygen and moisture during packaging, the device will be easily corroded and its life will be greatly shortened. Nitrogen can be introduced into the packaging area from the outside world, allowing the chip to safely complete the package.

In the testing process, nitrogen can also be used to simulate the actual use of the chip environment, to help engineers accurately assess the performance of the chip.

The sixth use welding link to prevent oxidation

in these welding processes of reflow soldering and wave soldering, the solder is easily oxidized at high temperature, and the welding quality will deteriorate after oxidation, and problems such as virtual soldering and bridging will easily occur.

Nitrogen can drive away the oxygen in the welding area, keep the solder clean, have better fluidity, and have higher quality and fewer defects.

Water Lubricated Air Compressor in Nitrogen Supply Role

having said the use of nitrogen, let's talk about how nitrogen comes from. In the factory, nitrogen production equipment is usually used to separate nitrogen from the air, and this process requires compressed air as raw material.

At this time, if the air compressor is lubricated with water to provide compressed air, there is a great advantage. The water-lubricated air compressor uses water instead of oil for lubrication, so the compressed air it produces is completely oil-free. With this clean compressed air to produce nitrogen, the purity of the nitrogen produced is easier to reach the standard, and the filtering burden behind is much smaller.

Moreover, the water-lubricated air compressor does not need oil change, so it is easier to maintain. Water is recycled in the machine. If it gets dirty over time, just replace it and clean the waterway. For semiconductor factories, which require long-term continuous gas supply and have extremely high gas quality requirements, water-lubricated air compressors are a very practical choice to work with nitrogen systems.

To sum up

nitrogen does six main things in a semiconductor factory. When the protective gas prevents the oxidation of materials, when the purging gas cleans the equipment and pipelines, when the carrier gas helps other gases transport, when the ambient gas maintains a clean positive pressure, when the protective umbrella is packaged and tested, and when welding, the solder is prevented from oxidizing.

The water-lubricated air compressor, because the produced air does not contain oil, can make the final nitrogen cleaner and more reliable when it is used to supply gas to the nitrogen system, which matches the strict requirements of the semiconductor factory on the purity of the gas.