Plasma processing apparatus and method

#This invention relates to an apparatus having a plasma generating mechanism and to a plasma processing method thereof; and, more particularly, the invention relates to a plasma processing apparatus, which is applicable for use in the fine processing of semiconductor devices, such as semiconductor manufacturing equipment and LCD equipment, and to a working method thereof.

#Recent semiconductor processing technologies have been required to have finer processing performance and higher production accuracy. Further, the conventional plasma apparatus, which decomposes process gases by use of a plasma and physically processes semiconductor wafers, cannot be free from the deposition of reaction products on the inner wall of the plasma chamber of the apparatus. This inevitable deposition of a reaction product tends to substantially affect the processing status of wafers. As wafer processing technology advances, this influence becomes greater and the resulting patterns on the semiconductor devices tend to vary, even through the input conditions of the apparatus are kept identical. In other words, this makes the production unstable.

#To solve this problem, conventional methods have employed cleaning of the inner walls of the chamber by plasma or controlling of the temperature of the chamber walls so that the reaction products will not deposit thereon. However, most of these methods are not sufficient to keep the wafer processing status identical, so that the wafer processing status keeps on varying gradually as the processing advances from wafer to wafer. Before the products are seriously affected, the plasma processing apparatus must be disassembled for parts replacement and wet cleaning, sometimes using ultrasonic waves. Besides the depositions on the chamber walls, the wafer processing status is also affected by various factors of the processing system, such as temperature. Therefore, various ideas have been employed to eliminate such influences. For example, detecting transitions in the processing status of the plasma processing apparatus and cleaning the chamber according to the result of detection, and feeding back the result of detection to the plasma processing apparatus to keep the processing status constant, have been proposed.

#FIG. 1 is a schematic block diagram of one embodiment of the present invention.

#FIG. 2 is a graphic representation of a specific vector in the operation of a signal filter of the present invention.

#FIG. 3 is a schematic block diagram representing part of FIG. 1 which is characteristic of another embodiment of the present invention.

#Various embodiments of the present invention will be explained in detail with reference to the accompanying drawings.

#FIG. 1 shows a first embodiment of the present invention. FIG. 1 is a schematic block diagram of a plasma processing apparatus equipped with a monitoring system. A process chamber 1 contains a gas supply means 2 to supply gases into the chamber, a gas exhausting means 3 which functions to exhaust the process gas and control the gas pressure in the chamber, a table 5 on which a specimen 4 to be processed is placed, and a plasma generating means 6 which generates a plasma in the chamber. The specimen 4 is a wafer in a semiconductor processing apparatus or an LCD device in an LCD manufacturing apparatus, for example.

#Device status detecting means 8a and 8b are added to this plasma processing apparatus. The status detecting means 8a is, for example, a current or voltage detector placed in a circuit which supplies power to the plasma generating means 6. The status detecting means 8a can be a current- or voltage-phase difference detector, a power forward-wave or reflected-wave detector, or an impedance monitor. When AC power is supplied to the plasma generating means 6, the status detecting means 8a needs to have a mechanism which Fourier-transforms the detected current or voltage, and creates and outputs a few to tens of signals classified by frequency. An electric status detector, such as the status detector 8a, can be placed in any of the plasma generating means 6, the specimen table 5, and the process chamber 1. Further, the electric status detector can be connected to the output of a plasma probe inserted into the process chamber 5.