Abstract: Metrology for a microlithographic objective reducing lens 10 is integrated into a metrology block 20 secured to a lower region of the barrel 15 for lens 10. Block 20 has a central opening 27 around a lowermost element 11 of lens 10; and block 20 mounts distance detectors 28 around central opening 27, a pair of microscope objectives 30 and 31, and a pair of X and Y mirrors 40 and 41.

Abstract: In the reticle positioning system disclosed herein, a unitary structure is machined to form both a frame for holding a reticle and a compound linkage permitting lateral and rotational movement of the frame within its own plane under the control of three servo motors generating controllable displacements.

Abstract: In the resist development method disclosed herein, the spin development of a resist coating on the surface of a semiconductor wafer is monitored by measuring light scattered back from the wafer surface from an incandescent source. During development, the sensed light level oscillates due to optical fringing caused by the thinning of the resist layer in the exposed areas and the fringe generated oscillation essentially stops when the development breaks through in the exposed areas. By comparing sample data obtained from the sensed light level with template data representing a known or characteristic behavior, a control point corresonding to the last fringe may be determined. Development is then terminated a calculated time after the control point.

Abstract: The calibration scheme disclosed herein is applicable to microlithographic systems of the type in which alignment between successive exposures is provided by means of a microscope mounted to one side of the optical projection column, there being a laser metered stage for transporting a semiconductor wafer between the microscope and an optical projection column. In accordance with the practice of the invention, a wafer with a light sensitive coating is placed on the stage and transported to the column using an approximate base line value. After exposure from a reticle which includes fiducial markings, the wafer is transported by the stage to the microscope. By observing the latent image on the coating, the precise stage movement required to align the latent image of the fiducial markings on the wafer with the microscope system reference reticle may be measured with the laser metered stage. The base line value is then corrected based on the actual measurement.

Abstract: In the microlithographic system disclosed herein, the spaces between elements in a projection lens are filled with flowing helium gas which substantially reduces the refraction errors caused by barometric changes in the atmosphere, even though the portions of the optical path outside the lens are exposed to the atmosphere.

Abstract: The wafer chuck disclosed herein is adapted to hold a semiconductor wafer during high energy treatment in a vacuum environment. The wafer is clamped by its rim to a circular domed plate so as to distort the wafer into close proximity with the domed face of the plate. Ports are provided in the face of the plate for introducing a mobile gas under controlled pressure to the interstitial space between the wafer and the domed face of the plate. An annular groove is provided around the periphery of the domed face and this groove is connected to a vacuum pumping means thereby to minimize leakage of the mobile gas into the vacuum environment.

Abstract: Analog-to-digital conversion and a computer produce finer resolution for interferometer distance measurement. The system applies to a laser interferometer producing two detected signals with voltages 19 and 20 that vary to form two sine waves in quadrature as interference fringes occur. A pair of analog-to-digital converters 21 and 22 converts each of these signals into digital values subdividing each sine wave fringe cycle into a plurality of increments. An up/down counter 25 supplied with a significant digit from each of the converters counts fringes corresponding to changes in path lengths. A computer 30 arranged with access to the fringe count and the digital increments determines a distance measurement based on the fringe count and a fine resolution of the distance measurement based on final values of the signals at any subdivided fringe cycle increments after changes in the path lengths.

Abstract: In the reticle bar code scheme disclosed herein, the peculiar characteristics and requirements of a microlithographic reticle are utilized in a bar code scheme which provides multiple levels of error checking while permitting an extensive repertoire of reticle identifying characters. In reading the bar code, the reticle is moved passed a photoelectric sensor and, by counting a clock signal, the width of each bar is measured. A synchronization character at the start of the data character string provides a nominal bar width value and each character comprises three bars of each polarity, the bars being integral multiples of the nominal value with the width of the character being ten times the nominal value.

Abstract: In the heat treating apparatus disclosed herein, semiconductor wafers are baked on the circular hot plate while being sheathed with a uniform vapor flow. The preferred vapor is a mixture of a relatively large volume of nitrogen carrying a relatively small volume of HMDS. After passing over the wafer, the vapor sheath is drawn, through an annular gap, into an exhaust chamber which surrounds and underlies the hot plate thereby avoiding heat and vapor loss into the other portions of the semiconductor fabrication line within which the baking apparatus is typically incorporated.

Abstract: A microprocessor controlled distillation analyzer for petroleum products performs, computes, displays and records distillation data. An interactive/keyboard display and printer system reports and records test conditions and prompts user inputs to define test parameters. Before the initial boiling point, the heater is automatically controlled in two time intervals. Following the initial boiling point, the heater is controlled to keep the monitored distillation rate within a predetermined range. Upon attaining an automatically calculated volume of distillate, the final heat is incremented to a programmed level. In one mode, the end point is automatically detected by monitoring vapor temperature for a decline, followed by the cessation of meniscus movement to terminate the test. After measuring the residue, the analyzer automatically recomputes temperatures at a series of percentage volumes of evaporated sample.

Abstract: Liquid hydrocarbon samples from a mainstream are diverted through a sample cell in cooling chamber. An optical cloud point detector signals a microprocessor-based control system which controls the charging and cooling of the cell. Cloud point reference level is continuously updated. After each measurement cycle, the control system readjusts the cooling power so that the time interval between the end of the flush cycle and cloud point detection is brought within a predetermined range. The control system switches between several distinct modes of operation automatically.

Abstract: In the resist baking apparatus disclosed herein, heating of the wafer is effected by direct contact with a thin disc-like heating plate whose heat capacity is not greatly disparate from that of the wafer. The heating plate is initially brought to a temperature higher than that which is to be applied to the resist but the corresponding cooling of the plate as the wafer is initially heated prevents damaging temperatures from reaching the resist. The heater plate is perforate and air pressure is utilized to support a wafer over the heater plate before heating is to begin and also to later lift the wafer and thereby sharply define the end of heating. During baking, a vacuum is applied through these same perforations to clamp the wafer tightly against the heating plate for tight thermal coupling.

Abstract: A heating device for use in laboratories and the like comprising an oven housing having a magnetron tube, power control circuitry for the magnetron tube, a timer for determining an amount of pulse power for the magnetron tube, a settable heating time switch with display, a settable venting time switch and display, and magnetron tube resistance heating structure directly, physically attached thereto with thermostatic control therefore for accurately, and by a predetermined amount, heating the magnetron tube prior to operation of the overall heating device. Because the temperature of the magnetron tube is very accurately maintained all of the changeable operating controls for the magnetron respond predictably and with a high degree of accuracy, and therefore when the heating device is used in laboratory applications for heating and drying a plurality of samples individually, each sample can be predeterminedly heated and dryed in a predicable manner like the previous samples.

Abstract: A linear measurement interferometer 10 with a measurement axis directed toward a surface of a work piece 17 has a light source 11, a detection system 12, and a beam splitter 13 arranged to divide light from the source into test beams 21, 22, and 34 and reference beams 23, 24, and 33 that travel test and reference paths and recombine for detection by the detection system. Beam splitter 13 is arranged on the measurement axis with the work piece surface on one side of the beam splitter and the test beam path straddling the measurement axis on the opposite side of the beam splitter. A test beam retroreflector 25 mounted in the test path on the measurement axis reflects back the test beam from beam splitter 13 and is movable along the measurement axis without causing abbe error.

Abstract: Catalytic etching is carried out by placing a pattern of a catalyst on a surface to be selectively etched and treating the imaged surface with an activated fluid which consumes the material being etched. In one embodiment a surface such as a chalcogenide is provided with a silver or other metal pattern corresponding to a semiconductor pattern and the chalcogenide is etched with an oxygen containing plasma reactive with the chalcogenide, the reaction being increased by the silver to provide a positive resist.

Abstract: Disclosed is a wax condenser for separating wax from an entrainer gas (or sweep gas) which is introduced into a sintering furnace and then pumped out in order to remove the wax from the furnace. The condenser includes a hot chamber and a cold chamber. Wax is removed by the condenser in three ways. After the entrainer gas enters the hot chamber of the condenser from the sintering furnace, it will pass through a heated filter. The heated filter will capture a large percentage of the wax present in the entrainer gas. The entrainer gas passes from the heated filter through a flow-restricting aperture which is located in a barrier separating the hot chamber from the cold chamber. This flow restricting aperture causes a pressure drop across the barrier. When the entrainer gas passes through the aperture, an expansion of the entrainer gas takes place due to the drop in pressure associated with the passing of the entrainer gas through the flow restricting aperture.

Abstract: The gas feed system disclosed herein is useful in a reactive ion etching system in which a gas plasma is energized by an electrode plate through which the gas is introduced. Propagation of the plasma discharge down the gas feed path is blocked by a feed system in which the space between a pair of porous metal plugs is filled with a porous insulating material having a pore size too small to support discharge, i.e. corresponding to the mean free electron path in the gas.

Abstract: In the air track system disclosed herein, reticles used in a microlithographic imaging system are transported on an air track and are guided from one side by means of vertically directed air jets which maintain an essentially controlled gap between the edge of the reticle and a side rail extending along the track.

Abstract: In the heat treating apparatus disclosed herein, a semiconductor wafer, held in a vacuum chuck, is traversed under an infrared source in which radiant energy from a linear, high intensity lamp is focused by an elongate elliptical reflector to generate a linear target zone through which the surface of the wafer is effectively scanned by the relative motion.

Abstract: A laser interferometer 10 uses light divided into reference beam 14 and test beam 15 traveling different paths from which beams 14 and 15 are reflected and recombined for detecting interference fringes. The path for test beam 15 is arranged to change in length with deviation transverse to its path. To do this, a reflective diffraction grating 25 is inclined relative to test beam 15 at the autocollimation angle of the grating to reflect the test beam back on itself from the inclined surface of the grating. Then transverse deviation of the region where test beam 15 is incident on grating 25 changes the path length of the test beam reflected from the inclined surface of the grating and allows a measurement.