RF Sputterer

Description

The RF sputterer was designed to deposit metals and metal-oxide thin-films in a relatively clean (~ micro Torr base pressure) environment. The RF sputterer is a versatile tool that can deposit a range of materials, since it is configured for reactive or nonreactive mode operation. Reactive sputtering refers to the formation of a compound that is different from the target material. Since this system uses metallic targets to form oxides, a reactive deposition requires the flow of oxygen during deposition.

Argon is used to generate a plasma
Oxygen is used to form metal-oxides, e.g. aluminum oxide, zinc oxide, hafnium oxide, titanium dioxide.

The system is constructed from stocked components from various vendors, e.g. Kurt J. Lesker, McMaster-Carr.

System Overview

substrate cooling: liquid nitrogen (LN2) is used for cooling the substrate (aka the anode) during deposition. This allows for the crystallinity of deposited films to be reduced towards the amorphous (zero crystallinity) state.
vacuum system: The turbo pump and roughing pump are used to lower the pressure of the system. The roughing pump inlet valve connects to the output of the turbo pump. In this way, the roughing pump doubles as a backing pump. If this is not a turbo-pump feature, then isolation valves must be inserted between the chamber and the roughing pump and between the turbo pump and the chamber.
- oil free pumps are used in an effort to reduce contamination of the system
gas system: argon and oxygen (not shown) are controlled via two separate mass flow controllers (MFCs), externally mixed, and fed into the system. An ion gauge is used to record the pressure of the system from microtorr levels to atmospheric levels.
power system: the system uses three independent 300W RF power sources with automatic matching networks. This allows co-sputtering of up to three material targets (cathodes) simultaneously.
- The cathodes are labeled gun 1, gun 2 and gun 3.
view port: a quartz viewport is used to visualize the plasma glow and sample during deposition.
- Note: this normally becomes coated and opaque after repeated use. A trick is to use a transparent disposable film that can be tossed out between runs.
frame: the frame was constructed from aluminum rail materials obtained at McMaster-Carr and the chamber was supported using heavy-duty pipe clamps.

Some photos of the system are given below.

Example: Complete system

Example: Plasma glow

Note: Image taken before anode was installed.

Example: Zinc Target

2" wide, 0.125" thick

Example: Target Housing

The target housing shown here is lowered for changing target materials.

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