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What Is Plasma Etching

Author: Source: Datetime: 2016-09-29 14:49:49
Why plasma etching is so important for solar powered portable generator ?When the temperature of the gas rises further, many or even all of the molecules or atoms will be due to the intense collision with each other. When the temperature of the gas rises, Dissociation into electrons and positive ions. At this time the material will enter a new state, that is mainly composed of electrons and positive ions (or positively charged nuclei) of the state. This state of matter called the plasma, it can be called the fourth state of matter. The principle of plasma etching is the use of high-frequency glow discharge reaction, the activation of reactive gases into active particles, such as atoms or free radicals, the active particles to be spread to the site to be etched, where the material reacts with the etching, the formation of volatile The reactants are removed.

Diffusion of the silicon wafer for etching reasons: the diffusion process, the peripheral surface of the wafer is also formed a diffusion layer, the peripheral diffusion layer of the battery to form a short-circuit electrode ring, you must remove it. Periphery on the existence of any small local short circuit will make the battery shunt resistance decreased, resulting in waste.The etching principle and method of etching the silicon wafer after etching are as follows.

Heat probe test method

When the thermal probe is in contact with the N-type semiconductor, the conduction electrons will flow to the lower temperature region so that the electrons at the thermal probe are reduced so that their potential will be positive with respect to the room temperature contacts on the same material; Type semiconductor heat probe contacts will be negative relative to the room temperature contacts. This potential difference can be measured with a simple microvoltmeter.

Test procedure

Make sure that the multimeter is working properly. The cold probe is connected to the positive electrode of the voltmeter and the thermal probe is connected to the negative terminal of the voltmeter.
With the cold, hot probe contact with a silicon edge is not connected to the two points, the voltmeter shows the voltage between these two points is negative, indicating the conductivity type P, etching qualified. The same method detects whether the conductivity type of the other three edges is P-type.
If tested, no edge of any qualified etching, this batch of silicon need to re-chip, the etching.

After completion of the etching process, the need for secondary cleaning process steps. The main purpose is to remove borosilicate glass produced during the diffusion process of boron or phosphorous-silica glass produced during diffusion of phosphorus. POCl3 decomposition of the P2O5 deposition on the surface of silicon, P2O5 and Si reaction SiO2 and phosphorus atoms. So that the surface of the silicon layer to form a layer of phosphorus containing elements of SiO2, called the phosphosilicate glass. Similarly, BBr3 also forms a layer of boron-containing SiO2 on portable solar power generator the surface of the wafer during the diffusion process. The difference between the two is that borosilicate glass is more difficult to remove than phosphorous-silica glass and needs to be removed by wet oxidation, electrolysis and the like, which makes the process of boron expansion complicated in the process.
portable solar_power generator with interchangeable battery for camping road trips
PECVD is the abbreviation of plasma enhanced chemical meteorology deposition. Plasma is due to the thermal motion of the material molecules intensified, the collision between the gas molecules so that ionization occurs, so that the material will become free movement and by the interaction of positive ions, electrons and neutral particles composed of a mixture. Surface passivation of the solar cell can be achieved by this process step. Effectively reduce the density of the surface state of the lifepo4 battery pack, reduce the minority carrier recombination of the solar cell, and improve the stability and reliability of the device. If the silicon solar cell emitter or base surface passivation, can effectively reduce the launch area and the base surface of the composite to improve the solar cell open circuit voltage, portable solar power generator which can improve the solar cell photoelectric conversion efficiency. Solar light-absorbing surface of the optical reflection film can effectively improve the solar cell absorption of light, thereby increasing the lifepo4 battery short-circuit current gain. The thickness of the antireflective film is 1/4 wavelength of the incident light, where the refractive index of the antireflective film is n and the wavelength of the incident light is?. , Can produce a minimum reflection d thickness determined by: mainly based on the 1/4 wavelength anti-reflection film principle. The reflected light returning from the second interface to the first interface is out of phase with the reflected light from the first interface, so the former counteracts the latter to a certain extent.

Printing and sintering

The solar cell with anti-reflection film is prepared and the electrode is prepared. Screen printing is used to prepare the lifePo4 battery electrode. The silver paste or silver / aluminum paste back electrode is printed on the back of the lifePo4 batteries. After drying, , And then printed on the front side of the battery silver paste before the electrode, and then sintering, sintering temperature control in the 800-880 ℃, so the completion of the crystalline silicon solar cell positive and negative electrode manufacturing.

Test sub-file

Screen printing and sintering of solar cells according to the appearance of color and electrical performance test results for sub-file. These are the international common production process of silicon cells, crystalline silicon solar cell efficiency in recent years, continuously improve, there are many new structures, new technology has been used for large-scale industrial production.
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