High density distributed microwave plasma sources in a matrix configuration: concept, design and performance

Abstract

Plasma scaling up can be achieved by distributing elementary microwave plasma sources over two or tri-dimensional networks. This concept is applied to a planar reactor comprising 4 × 3 microwave plasma sources distributed according to a square lattice matrix configuration. In each elementary plasma source, the plasma is produced at the end of a coaxial applicator implemented perpendicularly to the planar source. An argon plasma can be sustained in the medium pressure range from 7.5 to 750 Pa. The sheet of plasma thus obtained becomes uniform at a distance from the source plane of 15 mm, i.e. less than half the 40 mm lattice mesh. Using a cylindrical Langmuir probe, plasma density and electron temperature have been investigated as functions of pressure and microwave power. Results show that the plasma can reach densities between 10 12 and 10 13 cm −3 with a uniformity better than ±3.5%.

High deposition rates of uniform films in tetramethylsilane-based plasmas generated by elementary microwave sources in matrix configuration

“…It must be noticed that, in O 2 , the plasma density varies between 10 11 and 10 12 cm − 3 , i.e. nearly one decade less than the density of argon plasmas [7]. Density reaches about 10 12 cm − 3 for p O 2 = 7 Pa and P w = 1800 W. In N 2 , the plasma density increases from 0.7 to 2.25 × 10 12 cm − 3 at a 30 Pa nitrogen pressure.…”

“…A planar reactor, comprising 12 microwave plasma sources distributed according to a square lattice matrix configuration (4 × 3; lattice mesh of 40 mm), was designed [7]. A picture of the matrix plasma distribution operating for oxygen plasma is shown in Fig.…”

“…A complete and detailed description of the principle and the design of the so-called matrix plasmas is given in Ref. [7]. In particular, the elementary sources are fed with microwaves from many independent microwave circuits after division of the microwave power delivered by a unique 2 kW microwave supply.…”

“…The solution recently proposed is the generalization of the concept of plasma source distribution applied to ECR sources [5] to microwave plasma sources free from magnetic field. This novel kind of plasmas [7,8], so-called matrix plasmas, can generate uniform sheets of plasma over a wide range of argon pressure, from 7.5 to 750 Pa with densities between 10 12 and 10 13 cm − 3 at 20 mm from the source plane [7].…”

High electronegativity multi-dipolar electron cyclotron resonance plasma source for etching by negative ions

“…34 However, filament discharges are incompatible with most of the equipments used for micro-and nanoelectronic industry. Recently, a new type of ECR plasma source was build, namely, the multidipolar ECR, [36][37][38] which allows one to produce an easy scalable plasma source in various configurations, free of magnetic field in plasma volume, operating even below 10 mTorr. From the point of view of industrial applications, a negative ion plasma source that can provide the following characteristics is desirable: no contamination by filaments, no density jumps; negligible magnetic field in plasma volume; a density ratio of negative ion to electron higher than 50 (as to make it possible to bias the substrate positively without affecting the plasma potential, V pl , and to avoid overheating by electrons 33,34 ); stable operation at low pressure with no plasma potential drift; 34 good controllability of ion species and high etching rates.…”