Radio frequency electron cyclotron resonance plasma etching apparatus

#(1) Field of the Invention

#The present invention relates to an etching apparatus, and more particularly to a radio frequency electron cyclotron resonance (RF.multidot.ECR) plasma etching apparatus for use in etching a surface of a wafer or a substrate with the plasma produced by utilization electron cyclotron resonance phenomena.

#(2) Description of the Related Art

#The above and other objects, features and advantages of the present invention will be apparent from the following description of a preferred embodiment of the invention explained with reference to the accompanying drawings, in which:

#FIG. 1 is a diagram showing a structure of an example of a conventional microwave plasma etching apparatus;

#FIG. 2 is a diagram showing a structure of another example of a conventional microwave plasma etching apparatus;

#Now, a preferred embodiment of the invention will be explained with reference to the accompanying drawings.

#FIG. 3 shows a configuration of an example of the RF.multidot.ECR plasma etching apparatus according to the invention. The apparatus is provided with a plasma-producing chamber 1 and a substrate-transporting chamber (not shown) disposed adjacent to each other, the plasma-producing chamber 1 being for producing plasma by electron cyclotron resonance. The plasma-producing chamber 1 is connected to a gas system (not shown) which introduces a gas for producing plasma, and is provided with a coaxial cable 2 which introduces radio frequency waves for discharging and an antenna (electrode) 3. The antenna 3 may be in a disk form as shown in FIG. 4A or in a fork form as shown in FIG. 4B. The electron cyclotron resonance occurs based on an electric field introduced in from the antenna (electrode) 3 and a magnetic field from the permanent magnets 8 provided at the top of the plasma-producing chamber 1. As shown in FIG. 5, the permanent magnets 8 are provided in such a way that N poles and S poles alternate with one another and the movement of the electrons is in a loop. As a result, the magnetic lines of force are applied in parallel to the substrate 6 on a substrate holder 5 and the resonance magnetic field is uniformly produced at a location about 2 cm off the antenna (electrode) 3. The plasma thus produced is confined in a cusp field formed by a plurality of magnets 4 located around the periphery of the plasma-producing chamber 1. The plasma is thus spread and transported to the substrate while its density is maintained. The substrate 6 is applied with a radio frequency bias supplied from a radio frequency source 7, of several hundreds of KHz to 13.56 MHz for controlling ion energies.

#As explained above, in the RF.multidot.ECR plasma etching apparatus according to the present invention, since the radio frequency waves can be introduced into the plasma-producing chamber by the antenna, such introduction can be made uniformly in the plasma chamber having an inlet opening of a large diameter thereby enabling uniform plasma production. Also, since the coaxial cable can be used for the introduction of the radio frequency waves into the plasma-producing chamber without requiring waveguides or air-core coils and, furthermore, a low magnetic field is sufficient, the apparatus can be made compact and simple. Also, the magnetic line of force is applied in parallel to the substrate to be etched, which enables the radio frequency bias to be applied uniformly and which results in the realization of highly precise etching.