US 6835251

US 6,835,251 — High-Purity Aluminum Sputter Targets and Method of Manufacture

Title: High-purity aluminum sputter targets and method of manufacture
Patent number: US6835251B2
Inventors: Andrew C. Perry, Paul S. Gilman, Thomas J. Hunt
Original assignee / current assignee (as listed): Praxair ST Technology Inc (assignment recorded 2002-08-29 as PRAXAIR S.T. TECHNOLOGY, INC.)
Priority date: 2001-11-13 · Filing date: 2002-08-16 · Publication date: 2004-12-28 · Anticipated expiration: 2021-11-13 · Status (as listed): Expired – Lifetime
Application: US10/219,756 · Other version: US20030098103A1
Classifications: C23C14/34, C23C14/3407, C23C14/3414 (sputtering targets); C22F1/04 (working of aluminum)
Source: https://patents.google.com/patent/US6835251/en

Purpose. Conventional high-purity aluminum targets have recrystallized grains of roughly 500 µm to 5 mm, which "can contribute to poor sputter uniformity," and their limited strength often requires backing plates to control warping.

Plain-language scope. The target is at least 99.999 wt% aluminum (with 99.9995 wt% and 99.9999 wt% described), at least 99% recrystallized, with grain size under 200 µm — typically under about 125 µm, advantageously under about 100 µm, and most advantageously below about 80 µm. The face favorably shows at least about 35% (200) orientation (most advantageously ≥40%), with about 5–35% each of (111), (220) and (311). The method: cool a target blank below about −50 °C (e.g., −80 °C, or 77 K/liquid nitrogen), deform it to impose intense strain (advantageously ≥50% engineering strain; rolling, forging or pressing, with re-cooling between passes), recrystallize at below about 200 °C (below 100 °C, or below ambient), optionally "upquench" at below about 200 °C, then finish at low temperature. The rationale: maximize nucleation sites (N) while minimizing growth rate (G).

Not established by the excerpt. The excerpt omits claim language, so claim scope is not stated here; it also gives no data for most Examples, no complete Table 1, and no full reference list. Figures 1–3B are described only in part. The excerpt does not establish validity, enforceability, litigation, ownership changes beyond the recorded assignment, or prior-art effect.