Abstract: Method of heat treating semiconductor wafers in a continuous operation wherein the wafers are initially introduced into a tube where they are subjected to a heat treatment and then removed from the tube. The wafers are transported through the tube by a pair of horizontally disposed rods on which they are carried and by an additional guide rod which is located above the horizontal plane of the first rods. All three rods have a groove in the form of a screw thread into which the wafers may be seated. All three rods are caused to rotate in the same direction and the frictional contact of the wafers with the walls of each groove causes the wafers to rotate in the opposite direction from the rods while at the same time causing them to advance through the tube while being heated.