Automated high volume sputter deposition system
Complete PZT film stacks including bottom and top electrodes can be fabricated on 6” or 8” substrates in one run.

The sputter deposition tool for in-situ PZT deposition for both 150mm and 200 mm wafers is a Oerlikon cluster tool CLUSTERLINE 200 (CLN200). It consists of 2 load locks for wafer loading, a central robot for wafer handling and the sputter or etch modules for the depositions or the etching, respectively. Up to 6 process modules can be attached to the central robot handling and the tool can be optionally configured with 3 auxiliary stations (degasser, cooler and aligner) located close to the load locks.

The sputter module to deposit PZT by RF magnetron sputtering on 6” or 8” wafer consists of a vacuum chamber equipped with a turbo pump, a RF sputter cathode with impedance matching network and a impedance matching network for application of RF bias to the substrate.

To reach the very high substrate temperature required for an in-situ PZT deposition process a so called Very Hot Chuck for 6” and 8” wafer formats was developed. Further on the special design of the anode allows a very homogeneous sputter gas distribution and finally the installed RF bias capability enables to tune the film properties.

A maximum temperature of more than 800°C is achievable with the very hot chuck which is well above the chuck temperature range of 550 - 700°C necessary for in-situ deposition of PZT. Therefore the very hot chuck can also be utilized to deposit other materials which need an even higher temperature to grow in-situ in the required crystal structure such as BaSrTiO3 (BST).

Due to the separated heater circuits for the heating of the inside and outside area of the chuck and the design of the back gas inlet a very good temperature uniformity better than ± 2% could be achieved 

A maximum temperature of more than 800°C is achievable with the very hot chuck which is well above the chuck temperature range of 550 - 700°C necessary for in-situ deposition of PZT. Therefore the very hot chuck can also be utilized to deposit other materials which need an even higher temperature to grow in-situ in the required crystal structure such as BaSrTiO3 (BST).

Due to the separated heater circuits for the heating of the inside and outside area of the chuck and the design of the back gas inlet a very good temperature uniformity better than ± 2% could be achieved.

With the actual magnetron design a film uniformity of ± 5% was achieved (Figure 16). At 3 kW RF load power the deposition rate is about 1.1 nm/s. Due to the design of the symmetric sputter gas distribution with 8 gas inlets the tangential uniformity is typically ~1% which means a very good value.

Published December 11, 2012

The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2010-2013) under grant agreement n° 229196