A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition includes a microwave generator configured to generate microwaves at a frequency f, a plasma chamber that defines a resonance cavity for supporting a microwave resonance mode, a microwave coupling configuration for feeding microwaves from the microwave generator into the plasma chamber, a gas flow system for feeding process gases into the plasma chamber and removing them therefrom, and a substrate holder disposed in the plasma chamber and having a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use. The resonance cavity is configured to have a height that supports a TM.sub.011 resonant mode at the frequency f and is further configured to have a diameter that satisfies the condition that a ratio of the resonance cavity height/the resonance cavity diameter is in the range 0.3 to 1.0.

A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapor deposition, the microwave plasma reactor comprising: a microwave generator configured to generate microwaves at a frequency f; a plasma chamber comprising a base, a top plate, and a side wall extending from said base to said top plate defining a resonance cavity for supporting a microwave resonance mode, wherein the resonance cavity has a central rotational axis of symmetry extending from the base to the top plate, and wherein the top plate is mounted across said central rotational axis of symmetry; a microwave coupling configuration for feeding microwaves from the microwave generator into the plasma chamber; a gas flow system for feeding process gases into the plasma chamber and removing them therefrom; and a substrate holder disposed in the plasma chamber and comprising a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use; wherein the resonance cavity is configured to have a height, as measured from the base to the top plate of the plasma chamber, which supports a TM.sub.011 resonant mode between the base and the top plate at said frequency f, and wherein the resonance cavity is further configured to have a diameter, as measured at a height less than 50% of the height of the resonance cavity as measured from the base, which satisfies the condition that a ratio of the resonance cavity height/the resonance cavity diameter is in the range 0.3 to 1.0.

Methods and reactors are disclosed for producing synthetic material on a substrate by microwave plasma activated chemical vapor deposition. The method comprises the step of providing a microwave plasma reactor configured to provide a plasma having a toroidal shape. The reactor comprises a resonant cavity and a substrate holder arranged to hold, preferably, an annular shaped substrate or a plurality of substrates arranged in an annular configuration.

A plasma processing apparatus includes a processing container, an electromagnetic wave generator, and a resonator array structure. The processing container provides a processing space. The electromagnetic wave generator generates an electromagnetic wave for plasma excitation that is supplied to the processing space. The resonator array structure is formed by arranging resonators configured to resonate with a magnetic field component of the electromagnetic wave, each of the resonators having a size smaller than a wavelength of the electromagnetic wave, and is positioned in the processing container.

Bias supplies and plasma processing systems are disclosed. One bias supply comprises an output node, a return node, and a power section coupled to the output node and the return node. A resonant switch section is coupled to the power section at a first node, a second node, and a third node wherein the resonant switch section is configured to connect and disconnect a current pathway between the first node and the second node to apply an asymmetric periodic voltage waveform at the output node relative to the return node. The asymmetric periodic voltage waveform includes a first portion that begins with a first negative voltage and changes to a positive peak voltage, a second portion that changes from the positive peak voltage level to a third voltage level and a fourth portion that includes a negative voltage ramp from the third voltage level to a fourth voltage level.

An apparatus for large area plasma processing according to the invention comprises at least one plane antenna (A) having a plurality of interconnected elementary resonant meshes (M1, M2, M3), each mesh (M1, M2, M3) comprising at least two conductive legs (1, 2) and at least two capacitors (5, 6). A radiofrequency generator excites said antenna (A) to at least one of its resonant frequencies. A process chamber is in proximity of said antenna (A). Said antenna (A) produces an electromagnetic field pattern with a very well defined spatial structure, which allows a great control on the excitation of the plasma.

A resonance frequency can be adjusted by shifting the resonance frequency without reducing an impedance function or a withstanding voltage characteristic against a high frequency noise, when blocking, by using a multiple parallel resonance characteristic of a distributed constant line, the high frequency noise introduced into a power feed line from an electrical member other than a high frequency electrode within a processing vessel. Comb teeth M of a comb-teeth member 114 are inserted into winding gaps of air core coils 104(1) and 104(2). For example, first comb teeth M having a thickness m smaller than a standard thickness ts are mainly inserted in an effective zone A in a central portion of the air core coils. Further, in non-effective zones B at both sides or both end portions thereof, second comb teeth M+ having a thickness m+ equal to or larger than the standard thickness ts are arranged.

A plasma applicator includes a plasma discharge tube and a microwave cavity at least partially surrounding a portion of the plasma discharge tube. Microwave energy is coupled to the microwave cavity via a coupling iris. At least two orthogonal dimensions of the microwave cavity are selected such that the microwave energy in the microwave cavity propagates in a transverse electric (TE) mode. Primary electric fields generated from the microwave energy combine with an evanescent electric field generated from the coupling iris, such that a combined electric field in the microwave cavity is substantially uniform along the longitudinal axis of the plasma discharge tube. A plurality of radial microwave chokes is disposed over an exterior of the plasma discharge tube. Positions of the microwave chokes are such that microwave energy propagating in the TE mode and a transverse electric magnetic (TEM) mode is attenuated.

A plasma processing apparatus comprising: a processing chamber; an electromagnetic wave generator; a resonating structure formed by arranging resonators that are capable of resonating with a magnetic field component of electromagnetic waves; a measurement part configured to measure, for each frequency, a power of the electromagnetic waves traveling from the electromagnetic wave generator to the resonating structure and a power of transmitted waves, reflected waves, or scattered waves of the electromagnetic waves in the resonating structure; and a controller that performs measuring the power of the electromagnetic waves and the power of the transmitted waves, the reflected waves, or the scattered waves with the measurement part, and calculating a resonance frequency of the resonating structure based on frequency distribution of characteristic values of the resonating structure, calculated from the power of the electromagnetic waves and the power of the transmitted waves, the reflected waves, or the scattered waves.

A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition, the microwave plasma reactor comprising: a plasma chamber defining a resonant cavity for supporting a primary microwave resonance mode having a primary microwave resonance mode frequency f; a plurality of microwave sources coupled to the plasma chamber for generating and feeding microwaves having a total microwave power P into the plasma chamber; a gas flow system for feeding process gases into the plasma chamber and removing them therefrom; and a substrate holder disposed in the plasma chamber and comprising a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use, wherein the plurality of microwave sources are configured to couple at least 30% of the total microwave power P into the plasma chamber in the primary microwave resonance mode frequency f, and wherein at least some of the plurality of microwave sources are solid state microwave sources.