Plasma cleansing is the removal of dirt and contaminants from the surface through the use of plasma plasma or dielectric (DHD) plasmas made from gas species. Gases such as argon and oxygen, as well as mixtures such as air and hydrogen/nitrogen are used. Plasma is made by using high-frequency voltages (usually kHz to & gt; MHz) to ionize low pressure gas (usually about 1/1000 atmospheric pressure), although atmospheric pressure plasma is now also common.
Video Plasma cleaning
Method
In plasma, gas atoms are very interested in higher energy states and also ionized. When atoms and molecules 'relax' to their normal state, their lower energy releases light photons, this results in "light" or light associated with the plasma. Different gases provide different colors. For example, the oxygen plasma emits a light blue color.
Plasma-activated species include atoms, molecules, ions, electrons, free radicals, metastables, and photons in ultraviolet shortwave (UV vacuum, or VUV for short). This 'soup', which happens to be around room temperature, then interacts with the surface placed in the plasma.
If the gas used is oxygen, plasma is an effective, economical, safe method for the environment for critical cleanup. VUV energy is very effective in breaking most of the organic bonds (ie, C-H, C-C, C = C, C-O, and C-N) from surface contaminants. This helps break down high molecular weight contaminants. The second cleansing action is carried out by oxygen species made in plasma (O 2 , O 2 - , O 3 , O, O , O - , ionized ozone, metastasized excited metastase, and free electrons). This species reacts with organic contaminants to form H 2 O, CO, CO 2 , and low molecular weight hydrocarbons. These compounds have relatively high vapor pressure and are evacuated from the room during processing. The resulting surface is very clean. In Fig. 2, the relative content of carbon above the depth of the material is indicated before and after cleansing with oxygen excited [1] .
If the part to be treated consists of oxidizable materials such as silver or copper, inert gases such as argon or helium are used instead. Plasma-activated atoms and ions behave like molecular melting and can break down organic contaminants. These contaminants are re-evaporated and evacuated from the room during processing.
Most of these byproducts are small amounts of gases such as carbon dioxide and water vapor with trace amounts of carbon monoxide and other hydrocarbons.
Whether or not organic removal is complete can be assessed by measuring the contact angle. When organic contaminants are present, water contact angles with the device will be high. After the removal of the contaminant, the contact angle is reduced to the contact characteristics of the pure substrate.
If the surface to be treated is coated with a patterned conductive layer (metal, ITO) stored on it, treatment with direct contact with the plasma (capable of contraction to the microarcs) can be detrimental. In this case, cleansing by neutral neutral atoms in the plasma into a metastable state can be applied. The results from the same application to the surface of the glass sample are coated with the Cr and ITO layers shown in Fig. 3.
After treatment, the water contact angle drops to less than its value on the untreated surface. On picture. 4, the relaxation curve for the droplet trace is shown for the glass sample. Photos of the same droplets on the unreacted surface are shown in Fig. 4 insets. The surface relaxation time associated with the data shown in Figure 4 is about 4 hours.
Ashing plasma is a process whereby plasma cleansing is done for the sole purpose of removing carbon. Ashing plasma is always done with O 2 gas.
Maps Plasma cleaning
References
Source of the article : Wikipedia
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