Patent ID: 8423175

Claim:
A vertical thermal processing apparatus comprising: a thermal processing furnace; a substrate holder configured to be carried into the thermal processing furnace and to hold a substrate; a substrate transfer means including a holding arm configured to hold a substrate and a transfer base member configured to support the holding arm; a height-position detecting part disposed on the substrate transfer means, the height-position detecting part being configured to detect a height position of the substrate transfer means with respect to the substrate holder; a driving part controlled based on the height position detected by the height-position detecting part, the driving part being configured to relatively elevate and lower the substrate transfer means with respect to the substrate holder; a specific-portion detecting part disposed on the substrate transfer means, the specific-portion detecting part being configured to detect, when the substrate transfer means is relatively elevated and lowered with respect to the substrate holder, a substrate placed on each step of the substrate holder or a specific portion of the substrate holder, the specific portion having a specific relationship with respect to each substrate; a means configured to read the height position detected by the height-position detecting part, when the specific-portion detecting part detects the substrate or the specific portion; and a control part configured to control the substrate transfer means; wherein the control part includes: a difference detecting means configured to calculate a difference between a normal height position of each substrate or a normal height position of each specific portion, which height position is obtained by relatively elevating and lowering the substrate transfer means with respect to the substrate holder under the condition that the substrate holder is not subjected to a thermal effect, and a height position of each corresponding substrate or a height position of each corresponding specific portion, which height position is obtained by relatively elevating and lowering the substrate transfer means with respect to the substrate holder at a time of the operation of the vertical thermal processing apparatus; a judging means configured to compare the difference and a threshold value and to judge whether the transfer operation of the substrate from or to the substrate holder can be performed or not based on the comparison result; and a means configured to forbid the transfer operation of the substrate by the substrate transfer means, when the judging means judges that the transfer operation of the substrate can not be performed.