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Explore the capabilities of ALD coating systems for large substrate reactors, focusing on uniformity, scalability, and process optimization. Investigate coating processes for high aspect ratios and surface areas, including research plans and testing strategies.
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Facilities and Programfor Coating 8” Plates Jeffrey Elam, Anil Mane, Qing Peng, Joseph Libera Argonne National Laboratory LAPD Collaboration Meeting June 10, 2010
Argonne Flow-Tube ALD Coating Systems 36” 2” silicon witness 33 mm disc silicon witness
Thickness across the reactor Chemistry #1 • ~1% thickness increased at the “Si block” location • Thickness increased as high as 30% after MCP locations
Thickness across the reactor Chemistry #2 • No thickness deviations near MCP • Uniformity and ease of scaling in ALD are process-dependent
Large Substrate Reactor • Integrates with existing ALD reactors • Accommodates up to 12”x18” parts 12” 18”
ALD Indium-Tin Oxide in Large Substrate Reactor Cyclopentadienyl Indium /Ozone (O3) → In2O3 Very poor uniformity over large areas (± 45%) In2O3-catalyzed decomposition of O3
Improved ALD ITO Process • Standard Deviation=3.1% No ozone Excellent uniformity over large areas Process matters a lot
Large substrate testing: ALD Chemistry #2 Not optimized (same conditions as in flow tube)
Beneq TFS500 500 mm • Arrived: 5/18/10 • Commissioning : 6/28/10
Large Area Reaction Chamber for Beneq 10 trays Tray Bottom Tray top 17.5” 11.25”
Two 8”x8” Tiles in Beneq Tray Tray top Tray Bottom 8”x8” tile 8”x8” tile • 2 Tiles/Tray x 10 Trays = 20 Tiles per batch
Challenge: ALD in High Aspect Ratios For LAPD tiles, aspect ratio L/D = 60 Diethyl zinc (DEZ)/H2O → ZnO • Aspect ratio of capillary arrays does not limit the exposure times
Challenge: ALD on High Surface Areas Surface Areas of Capillary Glass: • Surface Area (SA) ~ 4αγAB (Jason McPhate, 12/09) • α = open area ratio = 0.65 • γ = aspect ratio L/d = 60 • AB = area of plate top sans pores , • 33 mm disc = 8.4 cm2 • 8”x8” tile = 412 cm2 • Surface Areas: • Empty ALD tube reactor: 600 cm2 • 1x 33 mm disc: 1310 cm2 • Empty large area reactor: 0.3 m2 • 1x 8”x8” tile: 6.4 m2 • Empty Beneq: 5.8 m2 • 20x 8”x8” tile: 129 m2
Coating High Surface Areas: Silica Gel Powder • 100 micron particles, 30 nm pores • Surface area = 100 m2/g, L/D ~ 2000 • Powder bed fixture for ~1 g support
Coating High Surface Areas: Silica Gel Powder trimethyl aluminum (TMA)/H2O → Al2O3 Planar Surface Silica Gel • Self-limiting growth on planar and porous surfaces • Exposures increased by x100
Layer-by-Layer Al2O3 ALD Planar Surface Silica Gel • Layer-by-layer growth on planar and porous surfaces
Outline of Research Plan • Single 8”x8” glass squares in large area reactor • Thickness uniformity with ellipsometry • Resistance uniformity with four-point probe • Composition with X-ray fluorescence (XRF) - destructive • Single 8”x8” capillary plate in large area reactor • Apply patterned electrodes (United Lens?) • Measure resistance uniformity • composition (XRF), thickness (SEM) – destructive • MCP testing? • Multiple 8”x8” glass squares in Beneq • Thickness uniformity with ellipsometry • Resistance uniformity with four-point probe • Composition with X-ray fluorescence (XRF) - destructive • Multiple 8”x8” capillary plates in Beneq • Apply patterned electrodes • Measure resistance uniformity • composition (XRF), thickness (SEM) – destructive • MCP testing?