Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/04—Apparatus for manufacture or treatment
  • H10P72/0431—Apparatus for thermal treatment
  • H10P72/0434—Apparatus for thermal treatment mainly by convection

Definitions

• the present invention relates to a baking oven for photovoltaic devices starting from semiconductor material, characterized in that the entrainment of the semiconductor material inside the oven is effected by means of a series of rolls made of a ceramic material which rotate on their own axis .
• photovoltaic devices involves, among the different types of treatment, various baking processes of the material, whose function is to fix doping elements, dispersed in solutions or in serigraphic pastes, or metallic contacts, onto the semiconductor.
• continuous ovens i.e. ovens in which the material is charged and processed without any interruption.
• the introduction of the semiconductor material into these ovens is typically carried out using a chain which, pulled by two rolls outside the muffle, passes through the oven.
• the chain in normally made of a metallic material which can cause contaminations on the part of metallic impurities in the semiconductor material treated;
• the temperature profiles at which the semiconductor ma- terial is subjected depend on the transport chain. This generally has a thermal inertia higher than that of the semiconductor material to be baked and consequently when moving, carries with it a considerable quantity of heat. Strongly varying profiles (for example 10-20°C/s) often necessary for optimal processes, can only be obtained with great difficulty.
• Patent application EP 1010960 relates to a baking oven for photovoltaic devices which is based on the noninteraction of the entrainment system with the heating sys- tern of the oven.
• the rolls which are made of quartz, are moved by means of a chain or belt, not individual, by friction.
• baking profiles are obtained by means of lamp heating, which can cause problems of stability and consequently uniformity; the en- trainment, moreover, can be subjected to non-uniformity as the movement of the rolls is not individual. Furthermore, the quartz rolls transparent to radiation selected for the heating of the semiconductors, are extremely expensive. It has now been found that it is possible to overcome the above drawbacks by using an oven in which the transporting of the semiconductor material through said oven, is effected by means of entrainment with ceramic rolls which rotate around their own axis by means of a shaft and belt drive .
• the objective of the present invention relates to an oven for the preparation of photo- voltaic devices from semiconductor material comprising:
• the housing preferably consists of ceramic material and the distance between one roll and another inside the housing, is such that the semiconductor material, during its rotating movement, rests on at least three of these.
• the ceramic material used in the manufacturing of the oven is selected from sintered silica, quartz and other material with a poor chemical interaction with the silicon.
• the semiconductor material which can be used for the preparation of photovoltaic devices is selected from slices of silicon, with thicknesses of 100-500 microns, or semiconductor materials in thin layers (films) which thicknesses varying from a few microns to 100 microns.
• the heating of the oven can be effected according to the known methods, by the use of electric resistances or infrared lamps .
• the temperatures inside the oven typically range from 100°C to 1200°C.
• Figure 1 illustrates an oven consisting of a certain number of rolls (1) in series made of sintered silica and the contemporaneous movement of all the rolls is due to an electric engine (16) by means of a shaft and belt drive (13, 11).
• the muffle (6) and its top (5), also made of sintered silica, are heated by a series of electrically-fed resistances (3) .
• the temperature is controlled with an electronic device to keep it constant.
• the oven is equipped with a frame (9) which encloses the insulation system (2) of the muffle, and has a removal system of the process fumes (18) .
• the devices obtained using the oven according to the present invention are free of metallic contaminants and are characterized by an excellent quality, allowing them to be used, for example, for the production of photovoltaic cells.
• EXAMPLE 1 An oven was produced for the diffusion of impurities of the phosphorous type with an entrainment system consisting of 300 rolls in series, made of sintered silica. The contemporaneous movement of all the rolls is due to an electric engine (16) by means of a shaft and belt drive (13, 11) . The muffle (6) made of sintered silica is heated by a series of electrically-fed resistances (3) .
• the temperature is controlled with an electronic device for maintaining a constant value. On selecting a set point of 900°C, the variation observed was less than 0.5°C. Slices of silicon on which a phosphorous doping agent had been deposited, were passed into the oven. The passage lasted about twenty minutes .
• the silicon slices thus obtained had an excellent diffusion of phosphorous impurities and could be used for the production of high-quality photovoltaic cells.

Landscapes

• Tunnel Furnaces (AREA)
• Photovoltaic Devices (AREA)
• Light Receiving Elements (AREA)
• Electric Stoves And Ranges (AREA)

Applications Claiming Priority (3)

Publications (1)

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Family Applications (1)

Country Status (6)

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• 2001
  • 2001-12-13 IT IT2001MI002628A patent/ITMI20012628A1/it unknown
• 2002
  • 2002-11-27 AU AU2002358050A patent/AU2002358050B2/en not_active Ceased
  • 2002-11-27 JP JP2003555596A patent/JP4511186B2/ja not_active Expired - Fee Related
  • 2002-11-27 WO PCT/EP2002/013372 patent/WO2003054975A2/en not_active Ceased
  • 2002-11-27 CN CNB028246241A patent/CN100356589C/zh not_active Expired - Fee Related
  • 2002-11-27 EP EP02791725A patent/EP1454367A2/de not_active Ceased

Non-Patent Citations (1)

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