The present invention relates to a novel process for manufacturing of Silicon Ingot from Metallurgical Grade Silicon for use in manufacturing of Silicon Solar Cell, in which the cost of the Solar Cell will be very very less and will be in high efficiency.
Silicon or semi conducting material is the material possesses Electrical characteristic which makes possible fabricating extremely useful devices including manufacturing of Photo Voltaic Cell which gives the maximum efficiency, long life span, easy to handle and absolutely maintenance free, etc.
This Silicon Ingot will be engaged in the generation, storage or distribution of electricity or any other form of energy.
The Metallurgical Grade Silicon is available in plenty, through out the world. Every day tons and tons of Metallurgical Grade Silicon is used in any Steel Plant. This substance is available'i-a very cheap rate. In metallurgical grade silicon the percentage of Silicon" is 93% ' to 9 5% only. But this much percentage of Silicon can be extracted in this novel pcocess to get, about 99.9 % pure Silicon.
The method of process is very simple and can be done with a very simple manner -as well as a very low price also. This invention relates to an improvement in a process, for preparation of Silicon Ingot from Metallurgical
Grade Silicon in electric oven, chiller, distillation unit and gas cracking unit. A mixture of gases with Metallurgical Grade Silicon in an electric oven to get Silicon Tetrachloride gas and then chilled it for liquidifying the gas, the same liquid gas to be distilled further for cracking in a cracking chamber, to get pure Silicon Ingot. From this Silicon Ingot very high efficiency Solar Cell can be made by slicing / cutting or making waffers from this Ingot.
Accordingly, the present invention provides a novel process for manufacturing of Silicon Ingot from Metallurgical Grade Silicon for use in manufacturing of Silicon Solar Cell wherein :
First, the metallurgical grade silicon is to be
created in H2SO2 or Hcl solution for 8 hours. 4
The same metallurgical grade silicon then to be
put in either a glass tube or in a metallic tube made
up of stainless stell. The same is to be heated up
in a electric-oven- at + 700 C. and Hydro§ein gas to
be passed inside the tube. The gas will pass through
the metallurgical grade silicon in the electric oven
and is brought into a reaction-in which Silicon
Tetrachloride and Trichloro Silane are formed. The
gas which is coming out of the tube to be made cool
down by passing the gas in a numbers of small tubes
connected in parallel and a cold air blower to be used for cooling these small tubes.
The gas which is coming out of the small tubes to be collected in a condensor , for getting it in liquid form. In the condnesor the tenperature to be maintained at + 7°C.
The same liquid gas again to be distilled in a distillation plant, by applying the heat at a temperature of + 85° G. to the liquid in an electric oven, through a condensor The temperature of the condensor to be maintained at + 7 C to liquidity the gas which is coming out from the electric oven. The liquidified gas to be; collected in a container, and the tenpersture of this container to be maintained at -5°C. So this container to be placed inside of a chiller.
After the filteration, the same liquid to be transferred in another chiller to maintain the temperature of the chiller at + 10° G. and Hydrogen gas to be passed in this liquid in two directions, one at the top of the liquid and another at the btottom of the liquid*
The mixture of gas which; is coming out from this liquid to be put in a cracking chafaber." Two electrodes are to be provided on both the sides of the cracking unit and the electric current to be passed through these electrodes, by means of a O.C. very high Aropare
current rectifier unit.
The gases which are coming out from the chiller are having free energy and it will get cracked by these electrodes when a D.C- very high Ampares current will pass through these electrodes.
Once the gas will crack, the Silicon will formed in a line between these two electrodes and then the current should be reduced to maintain + 600 C. temperature in the cracking chamber, ./hen the Silicon is cracked in the cracking chraber then the Silicon will deposit on the rod and the diameter of the rod will increase then the temperature of thgSilicon tod will decrease, at that time the current is required to increase to maintain a constant temperature inside the cracking unit by means of a Auto transformer. The current of the rectifier unit is depend upon the diameter of the silicon rod required.
After the required diameter of the Silicon rod is formed, the rod is then required for zone refining.
A zone refining machine is required whose temperature will be + 1500° C. and an area of 10 m.m. in Diameter.
The Silicon rod then to be put in the Zone refining machine and the Silicon rod to be melt from top to bottom very slowly in downward direction. In this process the silicon rod will get melted slowly from top to bottom and if any impurities are there, the same will be collected at the bottom of the
Silicon rod, afterwards these impurities can be eliminated by cutting out the portion from the Silicon Ingot. The ameter of the Ingot is depend upon the diameter of the Zone Refining Machine.
After getting the Silicon Ingot from the zone refining machine and as per the reguired diameter, the same is to be sliced or "cutted for making Silicon waffffrs as per the desired diameter and as per the required thickness. This cutting / slicing for making the silicon waffer3 can be done by a laser cutting machine or by U3ing a Silicon Carbide blade or a Silicon Carbide thin disc.
After making the Silicon waffers, chemical dopping to be done by putting the waffers in a De-mineralised water bath and with a few drops of HydroPloric acid are to be added on it. This bath i s to be put on a magnetic stirrer and" to stirrer up it for two hours. After that, again the Silicon waffers are to be put in De-mineralised water bath and with a few drops of Boron acid to be added in it and again to be stirrer up for one hour.
After chemical dopping., all the silicon waffers are to be put in an electric oven at a temperature of 120° C. for drying up the Silicon waffers.
Once the Silicon waffers are dried, then Titanium Silver paste to be applied by means of a screen printing machine for electrical connections on both sides of the Silicon waffers.
To prepare TiAg paste, Titanium dust of 30 % and Silver dust of 70 % to be mixed properly and thoroughly. After that a small quantity of De-mineralised water is required to add with this TiAg dust and to be put in a small mixture machine to get TiAg paste.
The TiAg paste is to be applied on the both sides of the Silicon waffers in a screen printing machine, and as per the desired size and shape as required for electrical connections.
After applying the TiAg paste on both the sides of the Silicon waffers, these Silicon waffers are to be kept in an electric oven at a temperature of + 750° G. for about 30 minutes.
In the electric oven, by keeping a temperature of +750 C. the Silver dust will get melt alongwith the "Titanium dust and the Silicon waffers will also be heated up to +750° C. by this method a solid bond will develop between the Silicon waffers and the TiAg Alloy, and the water will get vapourised. After this the Silicon waffers is to be made to cool down to get the normal temperature and pressure. Thus the Silicon Solar Cell is made.
There are numerous technical and economical advantages by this method. Firstly, with the process according to the invention some 90 % of the materials used are very cheap metallurgical grade silicon, thus greatly reducing raw material cost. Secondly, gas and acids which are also available freely and also in plenty and also in cheap rate. Thirdly the electricpower consumption is reducedd, only for electric ovens and chiller need electric supply. The advantages of protection of the environment may also be mentioned here.

I Claim :
1. A process for manufacturing of Silicon
I ngot from metallurgical grade silicon in or
relating to a process for use in manufacturing
of Silicon Solar Cell subject to heating to
bring about reaction between the metallurgical
grade silicon and the hydrogen gas to produce
Silicon Tetrachloride and Trichloro Silane and
distillation the siame and again cracking it to
produce silicon ingot,
Characterised by the improvement which comprises: -
(a) Silicon Tetracholride and Trichloro Silane.
(b) Distillation of Silicon Tetrachloride and Trichloro Silane.
(c) And cracking the Silicon Tetrachloride and Trichloro Silane.
(d) Thereafter, making high efficiency Silicon
Solar Cell.
2. A process as claimed in Claim I, where in Silicon Tetrachloride and Trichloro Silane are formed in step (a) at a temperature of +700° C. and then cool down to - 5° C.
3. A process as claimed in Claim 2 where in the Silicon Tetrachloride and Tri chloro Silane are separated in a distillation at a temperature between + 85° C.ta -5° C.
4. Aprocess as claimed in Claim 3 where in the Silicon Tetrachloride and Trichloro Silane are cracked in a cracking chamber by means of a high ampare current rectifier unit to get Silicon rod at a temperature of + 600°C
5. A process as claimed in Claim 4 where in the Silicon rod is Zone Refined in a. Zone Refining machine at a temperature of + 1500 C. to get the Silicon Ingot for manufacturing the. Silicon Solar Cell.
6. A process as claimed in Claim 5 where in the Silicon Solar Cell to be manufactured by making the Silicon waffers from the Ingot, doing chemical dopping and putting TiAg paste for electrical connections and keeping the same at a
temperature of + 750 C in an electric oven.
7. A process for manufacturing high efficiency
Silicon Solar Cell substantially as herein above
described with particular references to the
accompanying relevant data's.