Processing of Large Alumina Components of High Purity and the their Etching Behavior in a NF3/Ar Plasma Environment
| Autor: | ching-shan Lin, 林欽山 |
|---|---|
| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 Large alumina components, as large as 300 mm, of high purity are used in the chemical vapor deposition reactor chamber in 12-inch semiconductor processes, which can effectively resist plasma erosion. Hence, the shaping technology of green body is an important issue, in addition to an efficient and secure sintered body CNC machining procedure. In semiconductor processing, thin film is deposited not only on silicon wafers, but also on the alumina components inside the reactor chamber. In order to stably fabricate integrated circuits on silicon wafers, a plasma cleaning process must be applied to clean the interior wall of the reactor chamber. Accordingly, it is also necessary to study the relation between alumina and the plasma etching gas. In this study, alumina components were shaped by cold isostatic pressing, using spray-dried alumina granules of six different granule size distributions pressed under different pressuring profiles. The results indicated a high density could be achieved using an alumina granule with a wider distribution, and applying a larger pressure for a longer pressing time, which could substantially suppress the formation of a bimodal microstructure subsequent to sintering. A thermo-mechanical analysis could reveal the differences in sintering arising from the variations in granule size of the spray-dried powder and green body shaping pressure on the sintering behavior, which is crucial to the success of making large alumina components. In the CNC machining of the sintered components, three different diamond tools using different bonding matrices were compared, including Cu, Cu-15Sn, and Cu-15Sn-10Ti (wt%). Using Cu-15Sn-10Ti as the bonding matrix, a TiC layer was formed between the diamond grits and the bonding matrix, which effectively improved the retention of diamond grits during grinding. A self-dreesing effect was achieved in the diamond tool using Cu-15Sn-10Ti as the bonding matrix, which was evidenced in the vibration measurement during CNC machining and the frictional force measurement in pin on disk test. Alumina components of two different purity levels, including 99.90% and 99.14% respectively, were then etched in a NF3/Ar plasma environment, and wave length intensity ratio of fluorine ion (685.75 nm) to argon ion (750 nm) at 270℃, 300℃ and 350℃, respectively, were then recorded using an optical emission spectroscope. The intensity ratio was then transferred into Arrhenius plot and the activation energy for the etching of alumina could be resolved. Alumina of higher purity possesses a higher activation energy of etching and was more difficult to etch in a NF3/Ar plasma environment. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|