1. Field of the Invention
The present invention relates to a probe and a measuring device for measuring the density of particles such as atomics, molecules in a plasma atmosphere.
The present invention can be used for accurately measuring the particle density in the plasma atmosphere in order to accurately perform film deposition or etching using a plasma processing device or plasma.
2. Description of the Related Art
When a raw material gas is radicalized to deposit a thin film of a constituent of the gas on a processing target or to etch the processing target, in order to accurately control these processings, it is necessary to measure the density of atoms such as radicals in a plasma atmosphere to thereby control the generation of plasma. For this purpose, light is applied to a plasma atmosphere, and an atomic density is measured based on the absorption characteristic of this light.
As a device for measuring the atomic density, a device set forth in Japanese Unexamined Patent Application Publication No. 2004-354055 is known. According to this device, there are provided a hollow portion for introducing radicals formed at the front end of a tubular body, and a light source arranged in front of the hollow portion, and light is passed from the light source through the hollow portion and subjected to a spectroscopic analysis by a spectrometer provided at the base of the device. In this device, a lens is provided within the tubular body to make light linearly progress within the tubular body. Also, another device example is disclosed wherein at the base of a tubular body, a discharge light source is provided oppositely to a reflection plate arranged at the front end of the tubular body, and radicals are introduced into a hollow portion provided at the front end of the tubular body, wherein light is passed through the radicals and reflected by the reflection plate, and wherein the light is reflected in a 90 degree direction by a half mirror provided at the base of the tubular body, and a spectrometer is provided at a position forming an angle of 90 degrees relative to the light source. In this device also, a half-mirror is provided within the tubular body, and light is caused to linearly progress along an axis of the tubular body.
However, in each of the above-described devices, the tubular body does not guide light, but only performs a function as an enclosure that supports the discharge light source or the reflection plate provided at the front end of the tubular body and that protrudes the hollow portion introducing radicals from outside the reaction apparatus into a plasma atmosphere. Within the tubular body, a lens and the half mirror exist, which causes a problem that the diameter of the tubular body becomes large, as a matter of course. Consequently, the tubular body disturbs the state of plasma atmosphere, and has made it impossible to accurately measure a radical density in a true plasma atmosphere free of the tubular body. In addition, when measuring a radical density distribution within a plasma atmosphere while moving the tubular body, there has been a problem that an accurate radical density distribution cannot be measured since the large tubular body disturbs the state of plasma.