NOVELTY - The heat-treating inner chamber (3) for thermally processing a substrate (20), comprises walls (10), which surround an inner space (24) of the heat-treating inner chamber at all sides, a device for storing the substrate during the thermal processing, an energy source for introducing an energy into the inner space of the inner chamber, where a part of the inner sides of the walls are formed for reflection of the power introduced by the energy source, and a device for cooling the walls. The part of the inner sides of the walls consists of an infrared radiation highly-reflective material.    USE - Heat-treating inner chamber for thermally processing a substrate, which is useful for manufacturing thin film solar cells and/or thin film solar module.    ADVANTAGE - The heat-treating inner chamber can be simply and economically manufactured, and is capable of rapidly and effectively processing the substrate with less effort and high quality.    DETAILED DESCRIPTION - The heat-treating inner chamber (3) for thermally processing a substrate (20), comprises walls (10), which surround an inner space (24) of the heat-treating inner chamber at all sides, a device for storing the substrate during the thermal processing, an energy source for introducing an energy into the inner space of the heat-treating inner chamber, where a part of the inner sides of the walls are formed for reflection of the power introduced by the energy source, and a device for cooling the walls. The part of the inner sides of the walls consists of an infrared radiation highly-reflective material. The cooling device includes a circuit for a liquid cooling medium e.g. oil. One wall of the heat-treating inner chamber is provided with cooling channels, where 80% of the wall surface and/or all walls of the inner chamber are provided with cooling channels. The cooling channels run into the wall of the inner chamber in a meander-like manner, and have a rectangular cross-section. The adjacent cooling channels are separated by straps, whose width is 20-80% of the width of the cooling channels. The energy source comprises a heating unit for delivering thermal energy, where the heating unit is arranged in the heat-treating inner chamber. The heating unit is formed by quartz rods running parallel to the substrate surface. The quartz rods are arranged on both sides of the substrate surface. An intermediate reflector wall and/or an edge reflector are provided in the inner chamber for the reflection of the power radiated by the energy source. The inner sides of the inner chamber consist of infrared radiation highly-reflective material. The intermediate reflector wall and/or the edge reflector are formed in a manner, so that they focus the power radiated by the energy source on the substrate. An intermediate reflector for temperature homogenization is arranged between the cooled wall of the inner chamber and the substrate. The inner chamber comprises lockable openings for introducing and discharging the substrate. The inner chamber is connected with a conveying device for transporting the substrate and/or the substrate is housed in a substrate box. An INDEPENDENT CLAIM is included for a processing chamber for thermally processing a substrate.    DESCRIPTION OF DRAWING(S) - The figure shows a perspective sectional view of a processing chamber for thermally processing a substrate.    Processing chamber (1)    Heat-treating inner chamber (3)    Walls (10)    Inner space (24)    Substrate. (20)