An apparatus for transferring wafers by a robot blade and a method for using the apparatus are disclosed. In the apparatus, a robot blade that is equipped with distance sensors mounted in a bottom surface of the blade is provided which senses the distance between the bottom surface of the robot blade and an adjacent surface below the robot blade such that any possible scratching of the adjacent surface is eliminated. The adjacent surface below the robot blade may be a wafer surface in a wafer cassette, or a wafer pedestal surface in a process machine. The distance sensors are mounted in recesses in the bottom surface of the blade which may be suitably capacitance sensors, ultrasonic sensors or optical sensors. The distance sensed by the distance sensors is analyzed by a controller and compared to a predetermined value of a minimum allowable distance such that any danger of scratching the adjacent surface is eliminated.

A method and an apparatus for preventing particle contamination in a hot plate oven for curing a coating layer on a wafer surface are disclosed. The apparatus of a hot plate oven for curing a coating layer on the wafer without particle contamination can be constructed with an oven body of elongated shape; a plurality of metal heating blocks situated in the oven body arranged in a matrix form with a preset spacing there in-between; a pair of metal wafer carrying blades positioned in preset spacing between the plurality of metal heating blocks for moving both in a longitudinal direction of the oven body to traverse a wafer and in a vertical direction to load or unload the wafer from a planar top surface of the metal heating blocks; and an interlocking circuit for detecting an electrical short between any one of the pair of metal wafer carrying blades and any one of the plurality of metal heating blocks and for stopping the movement of the pair of metal wafer carrying blades when such electrical short is detected.

A baking unit, for use in photolithography equipment, has a sensing device for sensing whether components of the baking unit are level and whether particles are present on inner surfaces of the baking. The sensing device has a sensor unit and an optical element. The sensor unit is preferably mounted to the hot plate of the baking unit and includes a light emitter and a light detector. The optical element is preferably mounted to a cover of the baking unit at a position at which the optical element reflects/refracts light emitted from the light emitter to the light detector when the hot plate and the cover are level, and as long as particles are not present on the optical element.

A substrate center-finding method and apparatus, for determining the center of a substrate being passed through a substrate handling chamber of a substrate processing system, includes any number of sensors arranged in any configuration and permits the substrate to pass through any trajectory that triggers the sensors. The locations of the sensors are calibrated by homing in on the sensors using a point, the reference point, near the tip of an arm assembly on a substrate handler. The substrate handler has an encoder for sensing the pivot angles of links in the arm assembly, whereby the coordinates of the reference point can be calculated from the angles and lengths of the links. When the substrate triggers a sensor, the location of the reference point is again calculated, and the coordinates of the trigger point on the edge of the substrate is determined relative to the reference point. A suitable number of trigger points on the edge of a circular substrate will define a circle, so the center of the circle can be calculated, and the location of the substrate can be adjusted to account for any offset from the reference point.

A blade assembly for a mechanical wafer handling system. The assembly includes an elongated planar member having a central region, wherein the central region has a first array of openings and a second array of openings, the openings of the first array being arranged substantially symmetrically to the openings of the second array on opposing sides of a central longitudinal axis extending along the length of the planar member and passing through a center point of the central region. The openings in the first array are arranged substantially symmetrically with respect to a perpendicular axis extending along the width of the elongated planar member and passing through a center point of the central region. The openings in the second array are also arranged substantially symmetrically with respect to the perpendicular axis. The assembly also includes a wrist with a wrist upper cap and a wrist lower cap. The wrist upper cap has a first and a second wing support on two opposing sides of the upper cap and a first non-supporting narrow ridge extending between the first and second wing supports. The wrist lower cap has a third and a fourth wing support on two opposing sides of the lower cap with a second non-supporting narrow ridge extending between the third and the fourth wing supports. The wrist upper cap is attached to a top surface of the planar member and the wrist lower cap is attached to a bottom surface of the planar member when the blade assembly is assembled.