High efficiency RF matching network for ICP sources in industrial applications

Transcription

1 High efficiency RF matching network for ICP sources in industrial applications Dr. Rudolf Beckmann (Manz Coating GmbH) Dr. Roland Gesche, Joachim Scherer (Aurion Anlagentechnik GmbH)

2 Introduction Why aren t ICP sources not as widely used as CCP sources? To get an answer we have to look at the following Basics of CCP and ICP ICP: H-Mode (inductive) versus C-Mode (capacitive) Matching network circuits and efficiency Experimental: How to distinguish H-/C- mode Application in industrial environments

3 Classification of RF discharges (Kadetov 2004) RF discharges can mainly be divided into CCP and ICP Less known is that also an inductive set up can act in capacitive mode!

4 E-mode vs. H-mode H-Mode (no selfignition) H-Mode discharge impossible E-Mode (Kadetov 2004) An inductive antenna does not automatically produce a high density inductive plasma. Pressure and power need to be chosen properly!

5 E-mode vs. H-mode H-Mode (no selfignition) H-Mode discharge impossible E-Mode (Singh 2004) (Kadetov 2004) An inductive antenna does not automatically produce a high density inductive plasma. Pressure and power need to be chosen properly!

6 Standard matching network for ICP C 2 L Antenna RF Generator C 1 R Antenna + Plasma A highly efficient matching network can easily be built L-shaped. However, the asymmetry could cause inhomogeneous plasma density. How can it be made symmetric?

7 Symmetric matching network for ICP (Rayner 1996) Using a transformer, galvanic separation and symmetry are achieved. However, the use of a transformer reduces the efficiency. Losses of 30% or even more are typical. How could high efficiency and symmetry be combined?

8 Symmetric and high efficiency matching network for ICP C 1 Antenna RF Generator C 2 C 3 C 4 Plasma (DE U1) Using capacitors, the transformer can be avoided. Symmetry is created through innovative circuit design.

9 Symmetric and high efficiency matching network for ICP Simulations show that nearly symmetrical operation can be achieved by properly dimensioned capacitors: U1/U2 = 0.99 = 161 A principal phase error of approx. 20 remains due to R1 What is the benefit of this matching network design in practical applications?

10 Practical application: Efficiency of the matching network 3000 loss [W] transfomer based version Aurion (2012) 50% reduction of losses! HF-Power Input [W] The innovative matching circuit drastically improves efficiency. Standard transformer technology produces up to 2600 W losses! higher energy consumption, higher cost for RF generator and components, increased risk of not reaching the high density ICP mode

11 Practical application: Efficiency of the matching network 8E-07 7E-07 6E-07 ICP Mode: single energy high dense plasma 5 Pa 2,5 kw 5 KW 7,5 kw 10 kw I defined Ion energy 5E-07 di/dv 4E-07 3E-07 2E-07 CCP Mode: various energies low dense plasma 1E-07 V2 0E retarding Voltage [V] measure current by increasing retarding V2 Using sophisticated measurement techniques, it can be shown that real ICP mode is reached.

12 Practical application: Efficiency of the matching network 8E-07 7E-07 6E-07 5 Pa 2,5 kw 5 KW 7,5 kw 10 kw 8E-07 7E-07 6E-07 5 kw 1.0 Pa 2.0Pa 5.0Pa 8.0 Pa 5E-07 5E-07 di/dv 4E-07 di/dv 4E-07 3E-07 3E-07 2E-07 2E-07 1E-07 1E-07 0E retarding Voltage [V] 0E retarding Voltage [V] CCP -> ICP by increasing RF power! CCP -> ICP by decreasing pressure! Ion energy increases with increasing RF power! Ion energy increases with decreasing pressure!

13 Practical application: Manz VCS 1200 Al2O3, Si3N4, other processes High rate: > 6 nm/s Excellent uniformity: < +/- 2% over 330 x 330 mm² (2 sided) Start Video

14 Conclusion Why aren't ICP sources not as widely used as CCP sources? It is important to understand the different operating modes of ICP sources and to take proper measures to ensure operation in high density mode. For that a high efficiency matching network in combination with a well-designed ICP source and processing system are required. Then the advantage of ICP can be utilized in industrial applications.