Wafer boot cleaning device

Abstract

A wafer boot cleaning device comprising: a cleaning cavity; a remote plasma source in communication with the cleaning cavity for providing a cleaning plasma in the cleaning cavity; a vacuum extractor communicating with the cleaning cavity so that the cleaning cavity is in a negative pressure environment; and a wafer boat in which the silicon substrates of several solar cells are transported and which is housed in the cleaning cavity.

Description

[Field of Invention]The present usage model relates to a wafer boat cleaning apparatus, and more particularly, to a wafer boat cleaning apparatus for manufacturing a solar cell.[Prior Art]Solar cells have become widely used, are produced in large quantities, and there are increasing expectation of improving production efficiency.Solar cells are produced in a semiconductor process. However, since they are much larger than a wafer, the semiconductor process apparatus (e.g., a PECVD apparatus) is also correspondingly large. The furnace tube of the semiconductor processing apparatus for solar cells is equipped with a wafer boat mainly serving to fix the silicon substrates of a plurality of solar cells therein.Since there are a plurality of silicon substrates in the wafer boat, which have a length of about three meters, and after completion of a plurality of coating operations, the surface of the silicon substrate is also coated with a thin film, the latter must be cleaned and removed. At present, the most common cleaning method is to pull the wafer boat out of the furnace tube of the semiconductor process apparatus and bring it out of the outside for chemical pickling. The pickling process is summarized as follows: using a hydrofluoric acid solution with a concentration of 15-25%, dividing into three rounds of cleaning of 4-5 hours each; during the soaking and cleaning process nitrogen bubbles are regularly introduced and an about half hour rinsing is carried out; after pickling, a further rinsing with pure water is carried out for about 10 hours to ensure that the wafer boat is completely cleaned; subsequently, drying is carried out at a temperature of 100-120 degrees Celsius for a duration of 10-12 hours.Therefore, for cleaning a wafer boat having a length of about three meters except for the transport time, a working time of more than one day is required to complete the cleaning. In addition, the hydrofluoric acid solution is volatile and both operators and location require very high safety standards in work planning, which in fact has a disadvantageous effect on the production efficiency of the solar cells and has to be improved further.[Summary of the Invention]In view of numerous disadvantages of existing wafer boat cleaning technology in solar cell fabrication, the primary purpose of the utility model is to provide a novel wafer boat cleaning apparatus.The most important technical measure for achieving the above purpose is that the wafer boat cleaning apparatus comprises:a cleaning cavity;a remote plasma source communicating with the cleaning cavity for providing a cleaning plasma in the cleaning cavity;a vacuum extractor communicating with the cleaning cavity such that the cleaning cavity is in a vacuum environment; anda wafer boat in which silicon substrates of a plurality of solar cells are transported and which is accommodated in the cleaning cavity.As can be seen from the above explanations, the main function of the wafer boat cleaning apparatus of this model of use is to place a remote plasma source and a vacuum extractor outside the cleaning cavity. Upon power-up of the remote plasma source and the vacuum extractor, a plasma generated by the remote plasma source is directed into the cleaning cavity to dry remove a thin film deposited in a furnace tube of another semiconductor processing device on the surface of the wafer boat. The cleaning time is shortened to a few hours. Moreover, time and costs for transport can be saved, thereby reducing the risk of accidents during chemical pickling.[Brief Description of Drawings]FIG. 1 : shows a schematic cross-sectional illustration of a first embodiment of a wafer boat cleaning apparatus of the present use model. FIG. 2 : shows a schematic cross-sectional illustration of a second embodiment of a wafer boat cleaning apparatus of the present use model. FIG. 3 : a partial stereoscopic schematic illustration of a third embodiment of a wafer boat cleaning apparatus of the present use model. FIG. 4 : a partial cross-sectional illustration of FIG. 3. FIG. 5 shows a further side cross-sectional illustration of FIG. 3.[Detailed Description of Embodiments]The usage model provides a dry cleaning technology for wafer boats for producing solar cells. The technical content will be described in detail, with only a plurality of embodiments being combined with the drawings as follows.Referring first to FIG. 1, a first embodiment of a wafer boat cleaning apparatus of the present utility model includes a cleaning cavity 10, a remote plasma source 20, a vacuum extractor 30, and a wafer boat 40.In this embodiment, the cleaning cavity 10 may be a metal cleaning cavity, may be made of materials such as aluminum or stainless steel, and is not a furnace tube for semiconductor coating. Therefore, the cleaning cavity of the preset usage model is not connected to gas for a semiconductor deposition process and other equipment. In this embodiment, the inlet 14 of the cleaning cavity 10 is located at the top 13 thereof.Remote plasma source (RPS) 20 is connected to cleaning cavity 10 to provide a cleaning plasma in cleaning cavity 10. In this embodiment, the RPS 20 is secured to an outer surface 11 of the cleaning cavity 10. The RPS 20 mainly includes a plasma generation cavity 21 and an impedance equalizer 22. the plasma generation cavity 21 has a plasma outlet 201 and at least one gas inlet 202, the plasma outlet 201 communicates with the cleaning cavity 10, and the gas inlet 202 serves to supply a gas used for cleaning a thin film after ionization. In order to adapt the above-mentioned materials for metal cleaning cavities, the gas may be a fluorine-containing gas and may be selected from one or more mixed gases of NF 3, CHF 3, CF 4, NF 3, SF 6 and C 2 F 6 so that the ionized gas after entering the metal cleaning cavity does not etch the inner wall of the metal cleaning cavity. However, the impedance matching unit 22 is then connected to a radio frequency power supply unit 23 to input the radio frequency power supply to the plasma generation cavity 21. The gas in the plasma generating cavity 21 is dissociated to generate a cleaning plasma, which is then introduced into the cleaning cavity 10 through the plasma outlet 201. In an embodiment, the radio frequency power supply unit 23 is a radio frequency power supply unit 23 having a frequency of 400 KHz to 27.12 MHz, and the power may be 1000 W to 5000 W. The higher the frequency, the higher the plasma density and the ion concentration, the lower the energy consumption, but is not limited thereto.The vacuum extractor 30 is connected to the cleaning cavity 10 such that the cleaning cavity 10 is in a vacuum environment that is about 0.5 to 100 thor. In this embodiment, the vacuum extractor 30 is attached to another, opposite outer side 12 of the cleaning cavity 10. Thus, after the start of the vacuum extractor 30, a reduced-pressure extraction gas stream is generated in the cleaning cavity 10, which is directed uniformly into the cleaning cavity 10 together with a cleaning plasma of the RPS 20 which is located on an opposite outer side 11 and removes the thin-film particles formed after the removal.The wafer boat 40 is designed to support silicon substrates of a plurality of solar cells therein, and the size of the wafer boat 40 matches the inlet 14 of the cleaning cavity 10 so that it can be accommodated in the cleaning cavity 10 to perform a cleaning operation on a thin surface layer. In this embodiment, the wafer boat 40 is inserted into the cleaning cavity 10 through the inlet 14 of the upper surface 13 of the cleaning cavity 10, so that a solar cell manufacturer does not need to excessively extend its shop area to place the dry cleaning apparatus of the present invention, and the wafer boat 40 can be operated to extend into and out of the cleaning cavity 10 by cooperation with a lifting mechanism.In this embodiment, the wafer boat 40 may cooperate with the gas selected by the RPS 20 to use a graphite wafer boat to prevent the ionized gas from engaging a wafer boat body of, for example, quartz. In addition, the graphite wafer boat may include two heating electrodes 41 and 42. To improve the efficiency of the cleaning plasma acting on the thin surface layer of the graphite wafer boat, the present model of use may further include a heater power supply 50. The power supply device for heating is electrically connected to the two heating electrodes 41 and 42 of the wafer boat 40. Since graphite has a conductive property and its room temperature electrical resistivity is about (8-13)×10 -6 Ω·m, it can generate heat energy after direct application of an electric voltage. Therefore, graphite is also suitable as a heating material. In this embodiment, the heating power supply 50 is disposed outside the cleaning chamber 10 and may be a DC power supply. In another embodiment, the heating power supply 50 may heat the wafer boat 40 to a temperature between 150° C. and 250° C. In a further embodiment, the two outer sides of the graphite wafer boat extend outwards to the two heating electrodes 41 and 42, respectively.A cleaning cavity 10, which can accommodate a wafer boat 40 having a length of about three meters, basically takes over the following four steps of dry cleaning:11000-150000,5-230-60225002-330-60335003-530-60445003-1030-60As can be seen from the above table, the present usage model performs a dry cleaning operation and increases the output of the RPS 20 as well as the vacuum value generated by the vacuum extractor 30 with time to increase the efficiency of the thin film cleaning.In addition, in order to more uniformly distribute the cleaning plasma in the cleaning chamber 10, a nozzle 51 is disposed at the plasma outlet 201 in the cleaning chamber 10 corresponding to the plasma generation space 21. The nozzle 51 has a plurality of fine air passages 511 so that the cleaning plasma, after entering the cleaning chamber 10, enters these fine air passages 511 and distributes itself uniformly in the cleaning chamber 10.Continuing with FIG. 2, a second embodiment of the wafer boat cleaning apparatus of the present utility model. Most structures are the same as those of the first embodiment. However, the inlet 14 of the cleaning chamber 10 is formed on one of its outer sides 11 so that the wafer boat 40 can enter and exit transversely into the cleaning chamber 10. Moreover, the RPS 20 is disposed on the upper surface 13 of the cleaning chamber 10, the vacuum extractor 30 is disposed on the bottom surface 15 of the cleaning chamber 10, while the nozzle 51 is positioned on an inner upper surface of the cleaning chamber 10, so that the cleaning plasma of the RPS 20 above it can be uniformly distributed downward on entering the cleaning chamber 10 through the nozzle 51.Continuing with FIG. 3, a third embodiment of the wafer boat cleaning apparatus of the present usage model, the structures of which are largely identical to those of the first and second embodiments, is illustrated. However, it additionally includes a rotary bracket 60. the rotary bracket 60 is composed of a plate body 61, two electric insulation fixing blocks 63, and two rotary shafts 621. A plurality of electric insulating plates 611 are fixed to the plate body 61 with a thermal expansion distance maintained between the adjacent insulating plates 611. Moreover, two straight side plates 62 are attached to two sides of the plate body 61, respectively. The two straight side plates 62 serve to pass the two rotating shafts 621 therethrough, that is, after passing through the two opposite outer sides 11 and 12 of the cleaning chamber 10, the two rotating shafts 621 are further passed therethrough and fixed to the two straight side plates 62. In combination with FIG. 4, the two electric insulation mounting blocks 63 are respectively passed longitudinally through the electric insulation mounting blocks 63 and the corresponding electric insulating plate 611 with a mounting member 631, and then fixed to the plate body 61 to be clamped to the both outer sides of the wafer boat 40. In one embodiment, each electrical isolation mounting block 63 is L-shaped and is clamped between the two heater electrodes 41 and 42 of the corresponding exterior of the wafer boat 40. Moreover, the plate body 61 and its two straight side plates 62 are made of a solid metal material, while the electrical insulating plates 611 and the electrical insulation fixing blocks 63 are made of a ceramic material. When the second rotating shaft 621 rotates, the rotating support 60 and the wafer boat 40 thereon are rotated to more uniformly contact the cleaning plasma, thereby improving the cleaning effect.Referring to FIG. 5, in order for the wafer boat 40 to be more stable during rotation, each mounting block 63 corresponds to electrical insulation of the front side of the wafer boat 40, i.e., the front side of the heater electrode 42 located below, and a baffle 632 may be additionally added to block the displacement of the wafer boat 40 during movement.To cooperate with the graphite wafer boat heating structure, both outer sides of the graphite wafer boat are fixed on the rotary support 60 by means of the two electric insulation fixing blocks 63 and electrically insulated from the plate body 61 by means of the electric insulating plates 611 and the two electric insulation fixing blocks 63. Moreover, the two heating electrodes 41 and 42 are passed through a through slot 622 of the corresponding straight side plate 62 by means of an electric wire 501, and emerge from a corresponding outer side 11 of the cleaning chamber 10 to be electrically connected to the heating power supply device 50, as shown in FIG. 4.In summary, the wafer boat cleaning apparatus of this utility model is primarily directed to the setting of a remote plasma source and a vacuum extractor outside the cleaning cavity. When the remote plasma source and the vacuum extractor start, a plasma generated by the remote plasma source is extracted into the cleaning cavity for cleaning, respectively, to dry remove a thin film deposited on a surface of the wafer boat in a furnace tube of another semiconductor processing device. The work time for cleaning is shortened to a few hours, and moreover, time and costs for transportation can be avoided to avoid accidents of the pickling workers.The above is only an embodiment of the usage model and does not limit the usage model in any form. Although the usage model in the above form has been disclosed by the embodiments, it is not intended to be limiting of the usage model. All persons of ordinary skill in the art can use the technical contents disclosed above to make a slight change or modification as equivalent executions with equivalent same change without exceeding the scope of the technical solutions of the present usage model, but for any content that does not deviate from the technical solutions of the present usage model, all simple additions, equivalent changes, and modifications of the above executions based on the technical substance of the present usage model still fall within the scope of the technical solutions of the usage model.

Claims

A wafer boat cleaning apparatus comprising: a cleaning cavity; a remote plasma source communicating with the cleaning cavity to provide a cleaning plasma in the cleaning cavity; a vacuum extractor communicating with the cleaning cavity such that the cleaning cavity is in a vacuum environment; and a wafer boat in which silicon substrates of a plurality of solar cells are transported and housed in the cleaning cavity.The wafer boat cleaning apparatus according to claim 1, wherein the remote plasma source comprises: a plasma generation space having a plasma outlet and at least one gas inlet, the plasma outlet being connected to the cleaning chamber, and the gas inlet being for introducing a gas used for ionization; and an impedance equalizer connected to a radio frequency power supply unit for introducing a radio frequency power supply into the plasma generation space.The wafer boat cleaning apparatus according to claim 2 further comprises a nozzle mounted in the cleaning chamber, corresponding to the plasma outlet of the remote plasma source, and having a plurality of fine air passages.The wafer boat cleaning apparatus according to claim 3, wherein the cleaning chamber is a metal cleaning chamber; the gas used by the remote plasma source is a fluorine-containing gas; and the wafer boat is a graphite wafer boat, and the graphite wafer boat includes two heater electrodes.The wafer boat cleaning apparatus according to claim 4, wherein the fluorine-containing gas is selected from one or more mixed gases of NF 3, CHF 3, CF 4, SF 6 and C 2 F 6 ; and the negative pressure value in the cleaning chamber sucked by the negative pressure extractor is between 0.5 and 100 Torr.The wafer boat cleaning apparatus according to claim 5, further comprising a heating power supply device electrically connected to the two heating electrodes of the graphite wafer boat to output a power supply to the two heating electrodes and heat the graphite wafer boat.The wafer boat cleaning apparatus according to claim 6, wherein the heating power supply means is a DC power supply, and the graphite wafer boat heats to a temperature between 150°C and 250°C.The wafer boat cleaning apparatus according to any one of claims 1-7, wherein an inlet of the cleaning chamber for the wafer boat to be input is formed at an upper side thereof or an outer side thereof; the remote plasma source is disposed at the upper surface or an outer side of the cleaning chamber; and the vacuum extractor is disposed at a bottom surface or an opposite outer side of the cleaning chamber.The wafer boat cleaning apparatus according to any one of claims 1 to 3, further comprising a rotation support comprising: a plate body on which a plurality of electric insulating plates are mounted, a thermal expansion distance being maintained between adjacent electric insulating plates, and two straight side plates are respectively disposed on two sides of the plate body; two electric insulation fixing blocks respectively fixed to the plate body and clamped to the two outer sides of the wafer boat; and two rotation shafts first passed through the two opposite outer sides of the cleaning chamber and then passed through the two straight side plates and fixed thereto to rotate the plate body in the cleaning apparatus.The wafer boat cleaning apparatus according to claim 9, wherein each electrical insulation mounting block is passed longitudinally therethrough and the corresponding electrical insulation plate thereof by means of a fixing member, and then fixed to the plate body; and a fender is added for each electrical insulation mounting block, the fender corresponding to a front side of the wafer boat.The wafer boat cleaning apparatus according to claim 9, wherein each electric insulation mounting block is in the form of an "L"; the plate body and the two straight side plates are made of a metal material; and the electric insulating plates and the electric insulation mounting blocks are made of a ceramic material.The wafer boat cleaning apparatus according to claim 2, wherein the radio frequency power supply unit has a frequency of 400 kHz to 27.12 MHz and a power of 1000 W to 5000 W.

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