Abstract book of Annual Meeting of the Japan Society of Vacuum and Surface Science
Online ISSN : 2434-8589
Annual Meeting of the Japan Society of Vacuum and Surface Science 2023
Session ID : 1Ia01
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October 31, 2023
Vacuum properties of new anodised aluminium films
Hiroki KurisuKentarou FukudaNaoya FurunoEisaku KuninobuYukio Azuma
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CONFERENCE PROCEEDINGS FREE ACCESS

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Abstract

Anodizing is applied to the aluminum alloy of the structural material of chemical vapor deposition and etching equipment for semiconductor manufacturing to prevent degradation caused by reactive and corrosive gases. The anodized aluminum coating should be highly durable and have good vacuum properties. A new anodized aluminum coating with advanced durability and vacuum properties was developed, and its physical and vacuum-related characteristics were studied.

Conventional samples were prepared, including sulphate-anodized aluminium oxide with a thin sealing film (C-1), oxalic aluminium oxalate with a thin sealing film (C-2), and oxalic aluminium oxalate with a thick sealing film (C-3). To improve durability, an anodic aluminium oxalate oxalate coating was developed with no sealing treatment, a lower oxygen content and higher flexibility than conventional coatings. Surface SEM images of conventional and developed anodised aluminium samples are shown in Fig. 1. Conventional anodized aluminium samples display a foliated or needle-like surface structure, which can be attributed to the presence of the sealing film. The developed anodised aluminium has a comparatively smooth surface, but still has the pores characteristic of anodic oxidation.

The heat resistance of the prepared anodised aluminium coating samples was investigated by keeping them at a constant temperature for one hour and then counting the number of cracks that developed on the anodised aluminium surface. The heating temperatures were 70°C, 100°C, 150°C, 200°C, 250°C and 300°C. The results showed that sulphate-anodised alumina (C-1) with a thin sealing film and alumina oxalate (C-2) with a thin sealing film developed cracks in the sample heated to 100 °C, and the number of cracks in the sample increased at a higher heating temperature. The oxalic anodised aluminium oxalate sample (C-3) with a thick sealing film did not crack when heated to 100°C, but the sample heated to 150°C did crack. However, the developed anodised aluminium sample did not show any cracks when heated to 300°C. This suggests that the developed anodised aluminium oxide possesses high heat resistance.

Figure 2 shows the time dependence of the outgassing rate after vacuum pumping of the prepared anodised aluminium oxide samples from atmospheric pressure. The outgassing rate of the three conventional anodised alumina samples decreased with time but remained in the order of 10-4 Pam3s-1m-2 up to 20 hours and in the order of 10-5 Pam3s-1m-2 after 20 hours. The outgassing rates of the developed anodised alumina sample remained in the order of 10-5 Pam3s-1m-2 after 4 hours and in the order of 10-6 Pam3s-1m-2 after 30 hours. As a result, the outgassing rate of the developed anodised aluminium sample was an order of magnitude lower than that of the conventional anodised aluminium samples.

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© 2023 The Japan Society of Vacuum and Surface Science
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