Optical thin films deposition by MDECR-PECVD

Abstract

We designed and built Matrix Distributed ECR (MDECR) PECVD reactor dedicated for dielectric filters deposition and equipped it with multiple sensors for process control. Planar matrix geometry of plasma source is based on electron cyclotron resonance effect at 2.45 GHz microwave frequency and provides scalability of the deposition on large area substrates. High (up to 5 nm/sec) deposition rate obtained due to high dissociation efficiency and careful design of the gas injection system. Optical emission spectroscopy, quadrupole mass-spectrometry and spectroscopic and multichannel kinetic ellipsometry are installed for in-situ studies and control of the film deposition. We performed studies of the nature of high-density plasma discharge in silane, oxygen and nitrogen mixture and correlated its properties with optical and physical properties of deposited materials. To demonstrate the capabilities, a wide band gradient index antireflection coating on glass was realized by deposition of SiO x N y alloy thin films. The predefined variation of an index in a profile is obtained by changing the flows of precursors. Real-time control is performed with multi-channel kinetic ellipsometry.

Multilayer optical filters control by multi‐channel kinetic ellipsometry

“…Figure 1 shows the different parts of the reactor. A detailed description of this reactor is given in references [6,7]. The used UVISEL ellipsometer allows in-situ measurement of 32 different wavelengths, with a sampling period lower than one second.…”

“…Spectroscopic ellipsometry represents an accurate method for characterization of the index and the growth rate for the different materials based on silicon oxynitride. After characterization of the different materials, new data can be generated to simulate kinetic trajectories for multi-channel ellipsometry in real-time control [6].…”

“…It has a low absorption in the visible, which makes it suitable for optical applications. The advantage of using PECVD is the ability to control the index of the deposited layer by controlling the flows of the gas precursors, which are in our case silane SiH 4 , nitrogen N 2 and oxygen O 2 [5,6]. MDECR plasma reactors have a matrix arrangement of the microwave antennas generating the plasma.…”

Deposition of dielectrics using a matrix distributed electron cyclotron resonance plasma enhanced chemical vapor deposition system

“…The matrix distributed electron cyclotron resonance (MDECR) reactor [9] used during this study, consists of a 50 liter cylindrical vacuum chamber, connected to a 1600 l/s turbomolecular pump as shown in Fig. 1.…”