Patent Number: 06295332&
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in the FIGURE, the novel method 10 of improving x-ray lithography in the sub 100 nm range to create high quality semiconductor devices comprises the steps of providing for the use and development horizontal beams from a synchrotron or point source of x-ray beams 11. The preparation of submicrometer, transverse horizontal and vertical stepper stages and frames 12 is next. This step develops stages and frames comprised of light weight, honeycomb structure constructed of composite materials. Also, used in this step includes using air or gaseous bearings, vacuum clamping and mating surfaces, active weight compensation; linear actuators and a fine alignment flexure stage for a all six degrees of freedom. The third step provides a stepper base frame for the proper housing and mating of the x-ray beam 13. Techniques and equipment used in this step include beam alignment, vibration insulation used when connecting to a stationary x-ray synchrotron or point source. The forth step is minimizing the effects of temperature and airflow by means of an environmental chamber 14. This unit is designed to control the temperature and humidity and, at the same time, minimize particle and molecular contamination. The fifth step is designed to transport, handle and prealign wafers and other similar items for tight process control 15. This step is required to produce high quality semiconductors. All critical wafer and mask handling and treating processes should be operated in a cluster like environment--the processes include coating, pre-baking, aligning and exposure, post baking and quality control. The sixth step is improving the control and sensing of positional accuracy through the use of differential variable reluctance transducers 16. The differential variable reluctance transducer provide a positional feedback for the six degrees of freedom alignment stage. The next step controls the continuous gap and all six degrees of freedom of the wafer being treated with a multiple variable stage control 17. The step uses an advanced multiple variable stage control that is designed as a cross coupled gantry in order to optimize the precise alignment of the device levels. Alignment systems are then incorporated using unambiguous targets in order to align one level to the next level 18. The alignment systems consist of multiple bright fields optical microscopes, normal to the plane of imaging to provide axis x, y and z, magnification and rotational data in order to align one level with the next level. Also, an additional imaging broad band interferometer alignment system is used to provide precise alignment of wafer levels and gap control during the x-ray exposure. The following step in the process is to use beam transport shaping or shaping devices to include x-ray point sources 19. This step uses steppers to interface an x-ray source mechanical interface and a vacuum or helium tight quick coupling. A beam transport chamber is used, either a snout design small unit or a large design integrated into the stepper base frame or as a full chamber designed for helium and or other low attenuation at atmosphere or lower pressure. The next step 20 uses an in line collimator or concentrator for collimating or concentrating the x-ray beams, along with the use of shutter and x-ray pulse controls. Mask magnification control is provided to allow for a mix and match with optical lithography levels and techniques. Finally, in the last step 21, the process images the pattern at the precise moment for optimum effectiveness. The whole process is repeated again to image the entire wafer or substrate with the mask pattern. The wafer or substrate is removed as in step number 15 and then repeated again and again until all wafers or substrates are imaged. While we have described our invention in connection with specific embodiments thereof, it is clearly to be understood that this is done only by way of example and not as a limitation to the scope of our invention as set forth in the objects thereof and in the appended claims.