Ceramic Target Magnetron Sputtering

Ceramic target sputter processes utilize ceramic targets made by sintering or hot isostatic pressing (HIP). For lab-scale R D work, another option is to use powder targets for sputtering [104]. 

RF sputtering is necessary when dielectric compounds such as sintered Zn0 Al203 disks are sputtered [58], Since about 1995, it has been possible to make conductive sintered ceramics due to reducing annealing of the ceramic or due to incorporation of special dopants [80] on a large scale. When the conductivity of the target material is sufficient, it is possible to use either MF, pulsed, or DC plasma excitation for sputtering. 

Properties such as high density and homogenous conductivity define the quality of ceramic targets. Ceramics with nonconductive inclusions exhibit arcing and nodule growth on the target surface, while targets with low density exhibit inferior film properties due to contaminations with different species. 

The properties of ZnO Al films for the application as the front electrode in a-Si H p-i-n solar cells have been compared by Muller et al. [106], 

A strong advantage from a process viewpoint is the fact that the Al enrichment for ZnO Al films deposited by reactive magnetron sputtering at 

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Fig. 5.20. Dependence of film composition of ZnO Al films deposited by ceramic target magnetron sputtering on substrate temperature (from [107])...

Fig. 4.15. Binding energy difference between Zn2p3/2 and O Is core levels and between the core levels and the valence band maximum. Films are deposited by dc magnetron sputtering from undoped and 2 % Al-doped ceramic targets at room temperature in dependence of sputter gas composition (left) and in pure Ar in dependence on substrate temperature (right). All films were deposited using a total pressure of 0.5 Pa, a sputter power density of 0.74 W cm-2 and a substrate to target distance of 10 cm...

The RF Magnetron sputtering of ceramic ZnO targets [97,98] offers fewer degrees of freedom for process optimization compared to the technology... 

Fig. 5.19. Comparison of reactive and ceramic target sputtering processes. The relative target costs are a rough estimate for planar magnetron targets (from [105])...

Fig. 5.23. Deposition system (a) and distribution of resistivity (b) for ZnO Al film deposition by ceramic target (sintered ZnO 2.0wt% AI2O3) DC magnetron sputtering. Ts = 150°C (open triangle), 300°C (open circle), 325°C (open square) and 350°C (bullet) (reprinted from [115])...

At first we have investigated the stmcture of ZnO layers grown by dc-magnetron sputtering of ZnO Ga ceramic target, as a function of the distance between the target and the substrate. 

The AlO,- insulator layer was deposited on the ITO by rf magnetron sputtering (13.56 MHz) from a planar AI2O3 ceramic target of 99.99% purity in pure Ar (99.998%). The sputter gas pressure was 8 x 10 mbar. This yielded AlO deposition rates between 4.0 nm/min and 6.0 nm/min. The base pressure prior... 

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