Abstract: Apparatus and method for aligning a rotatable substrate to a support mechanism to write a feature to the substrate, and a substrate so configured. In some embodiments, the substrate has a circumferentially extending timing pattern with spaced apart first and second timing marks disposed on opposing sides of a center point of the timing pattern and an identification (ID) field that stores a unique identifier value associated with the substrate. Upon mounting of the substrate to a support mechanism that rotates the substrate about a central axis that is offset from the center point, a control circuit generates a compensation value to compensate for the offset using the first and second timing marks and outputs a process instruction to authorize processing of the substrate using the unique identifier value. In some cases, the unique identifier value is used as a lookup to a computerized database.

Abstract: Apparatus and method for aligning a rotatable substrate to a support mechanism to write a feature to the substrate, and a substrate so configured. In some embodiments, the substrate has a circumferentially extending timing pattern with spaced apart first and second timing marks disposed on opposing sides of a center point of the timing pattern and an identification (ID) field that stores a unique identifier value associated with the substrate. Upon mounting of the substrate to a support mechanism that rotates the substrate about a central axis that is offset from the center point, a control circuit generates a compensation value to compensate for the offset using the first and second timing marks and outputs a process instruction to authorize processing of the substrate using the unique identifier value. In some cases, the unique identifier value is used as a lookup to a computerized database.

Abstract: Apparatus and method for aligning a rotatable substrate to a support mechanism such as a turntable. The substrate has a circumferentially extending timing pattern comprising at least spaced apart first and second timing marks disposed on opposing sides of a center point of the substrate. The substrate is configured to be mounted to and rotated by the support mechanism about a central axis. The center point of the substrate may be offset from the central axis by an offset distance due to mechanical tolerances associated with the substrate mounting operation. The offset distance may be determined through successive detection of the first and second timing marks by a detector over at least one rotation of the support mechanism and the substrate. A write beam may be adjusted using the determined offset distance to write a second feature to the substrate in alignment with a previously written first feature.

Abstract: Purification process for chromium metal is conducted on chromium metal powder which has been compacted without additives at a pressure of at least 50,000 psi (35.times.10.sup.7 Pa) into a compacted body having a critical diffusion dimension of less than or equal to 25 mm. The purification process uses a hydrogen gas treatment at a temperature of 1200.degree. C. to 1600.degree. C. for a period of 2 hours to 10 hours using 0.8 m.sup.3 per Kg chromium metal of hydrogen gas or more. The hydrogen treated chromium metal compacted body is then further treated under vacuum at a pressure less than or equal to 100 .mu.m of Hg (15 Pa) at 1200.degree. C. to 1600.degree. C. for 2 hours to 10 hours. The combined hydrogen and vacuum treatment reduces the oxygen, carbon, sulfur and nitrogen impurities in the chromium metal and results in a chromium metal suitable for metallurgical and electronic applications.