CVD reactor with graphite-foam insulated, tubular susceptor
The invention relates to a device for depositing especially crystalline layers on especially crystalline substrates by means of reaction gases fed to a heated process chamber. Said process chamber is formed by the cavity of an especially multi-part graphite tube arranged in a reactor housing that especially comprises quartz walls. Said reactor housing, in the area of the process chamber, is enclosed by a high-frequency coil and the space between the reactor housing wall and the graphite tube is filled with a graphite foam sleeve. In order to improve heat insulation, the graphite foam sleeve is fully slit. The slot is wider than the maximum thermal elongation of the graphite foam sleeve in the peripheral direction to be expected when the device is heated up to process temperature.
1. Device for depositing in particular crystalline layers on in particular crystalline substrates by means of reaction gases which are introduced into a process chamber which has been heated to a process temperature, the process chamber being the cavity in an in particular multipart graphite tube which is disposed in a reactor housing which in particular has quartz walls and which is surrounded by a high-frequency coil in the region of the process chamber, the space between the reactor housing wall and the graphite tube being filled by a graphite foam sleeve, characterized in that the graphite foam sleeve has a continuous slit running in the longitudinal and radial directions, the width of the slit being greater than the maximum expansion of the graphite foam sleeve in the circumferential direction which is to be expected during heating to the process temperature, wherein the slit, which runs substantially parallel to the longitudinal extent (axial direction) of the graphite foam sleeve, does not run in a straight line in the radial direction, and wherein the slit has a V-shaped profile.
2. Device according to claim 1 , characterized in that, over the entire slit length, the sleeve inner wall section adjacent to the slit is at a gap spacing from the outer wall of the graphite tube which is greater than the maximum expansion of the graphite foam sleeve and of the graphite tube which is to be expected during heating to the process temperature.
3. Device according to claim 1 , characterized in that the graphite tube has a substantially rectangular cross section, and three outer walls lie at a gap spacing from the sleeve inner wall.
4. Device according to claim 1 , characterized in that the slit is disposed approximately in the center of the graphite foam sleeve wall which is on the opposite side from the graphite tube wall which is in physical contact with the sleeve.
5. Device according to claim 1 , characterized in that the slit width and/or the gap width is between 0.5 and 1 mm.