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1266 |
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Tuesday, June 03, 2008, Room 05 3:00 PM Case Studies and Further Applications 2 showing the broad variety of thermal spraying in different examples, special processes and also specialised materials apart from standard coatings offer new possibilities and also new markets |
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Plasma sprayed coatings of high purity ceramics for semiconductor and flat panel display production equipments |
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Junya Kitamura* / Fujimi Incorporated, Japan Hiroyuki Ibe / FUJIMI INCORPORATED, Japan Hiroaki Mizuno/ FUJIMI INCORPORATED, Japan Isao Aoki/ FUJIMI INCORPORATED, Japan |
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High purity oxide ceramic materials, such as alumina and yttria, have been developed for Si semiconductor and liquid crystal display (LCD) production equipments. Erosion properties of high purity ceramic coatings for chamber shield of the equipments have been investigated against CF4 containing plasma, which is used at dry etching process for micro-fabrications of the Si and LCD devices. High anti-erosion resistance against the process plasma tends to retain smoother surface after the erosion test, in general. In spite of the almost same erosion rate within the yttria coatings whose durability is superior to alumina coatings, the coating formed by agglomerated-and-sintered powder consisting of large primary particle has smoother eroded surface than other coatings formed by smaller primary particle. Considering that contamination on the Si and the LCD glass substrate by particles, the surface of the chamber shield should be smoother to inhibit generation of large sized particles, which is easily deposit onto the wafers. Therefore, larger primary particle will be better choice to increase yield ratio of the devices because generated particle size will be smaller that is easily evacuated from the process chamber. In conclusion, we have found that the primary particle size of the agglomerated-and-sintered yttria powder is important property for the coating in this application. Electric insulating properties of the coatings are also investigated to apply to electrostatic chuck. Electric breakdown voltage of yttria coatings is almost comparable to that of alumina coatings. However, yttria is difficult to apply due to its lower mechanical strength. Using smaller particle as feedstock is effective to improve the electric insulating properties and the purity of the coatings less affects them. |