Specific Process Knowledge/Thin film deposition/ALD Picosun R200: Difference between revisions

The ALD1 (Picosun R200 ALD) tool is used to deposit a very thin layer of Al₂O₃, TiO₂ (amorphous or anatase), HfO₂, ZnO and AZO (Al-doped ZnO) on different samples.  

Each process is using two (or three for AZO) different precursors. The reaction takes place in cycles. During each cycle, a very short pulse of each precursor is introduced into the ALD reaction chamber in turns, and in-between each precursor pulse the chamber is purged with nitrogen. All reactions have to take place on the sample surface, thus it is very important that each precursor is removed from the chamber before the next one is introduced. In that way, the ALD layer will be deposited atomic layer by atomic layer.  

In order to ensure that the ALD reactor has the same temperature everywhere, it has a dual chamber structure. The inner chamber is the ALD reactor with a sample holder, and the outer chamber is a vacuum chamber that is isolating the reactor from room air. The space between the two chambers is called an intermediate space (IMS). The IMS is constantly purge with nitrogene.  

When the reactor chamber is heated up or cooled down, it will take some time before the sample holder and the sample reaches the desired temperature. Thus, it is important to include a temperature stabilization time in the process recipes.  

The ALD deposition takes place in the reactor chamber. All precursor and nitrogen carrier gas lines are connected to the reactor chamber through separate gas lines. The precursor pulse time is controlled using special ALD valves, that allow very short precursors pulses to be introduced into the ALD reactor and at the same time allow a constant nitrogen purge.  

The ALD reaction takes place under vacuum, thus a vacuum pump is connected to the bottom of the ALD reactor. The pump is located in the basement.  

The liquid precursors (H₂O, TMA, TiCl₄ and TEMAHF) are located in the cabinet below the ALD chamber. DEZ (diethylzinc) is located in a metallic box outside in the service room. When the DEZ, TMA, TEMAHf and TiCl₄ precursors are not in use, the manual valves have to be closed. Ozone is generated by use of an ozone generator that is located on the side of the machine.  

It is possible to change the sample holder, so that ALD deposition can take place on different samples, e.g. a small wafer batch or a number of smaller samples. Samples are loaded manually into the sample holder by use of a tweezer. However, for some materials the uniformity will only be good for the top sample(s) in a minibatch holder.     

*[[/HfO2 deposition using ALD|HfO₂ deposition using ALD 1]]

*[[/HfO2 deposition using ALD new page|HfO₂ deposition using ALD 1 new page]]

*Al₂O₃

*HfO₂

*AZO (Al-doped ZnO)

*HfO₂: 0.827 nm/cycle

*HfO₂: 0 - 50 nm

|style="background:LightGrey; color:black"|Temperature

*Amorphous TiO₂: 100-150 ^oC

*Anatase  TiO₂: 300-350 ^oC

*ZnO: 100 - 250 ^oC

*HfO₂: 150-300 ^oC

*O₂

*TMAHf

*Other metals (use dedicated carrier wafer)

*III-V materials (use dedicated carrier wafer)

*Polymers (depending on the melting point/deposition temperature, use carrier wafer)