JPS598775B2 - Active gas partial pressure measuring device - Google Patents

Description

[Detailed description of the invention] The present invention relates to an active gas partial pressure measuring device.

In the past, measurement of active gas concentration was indispensable in various chemical plants and research and development of corrosion and metal surface reactions.
It has been difficult to measure with good reproducibility over a wide pressure range. For example, when trying to measure active gas with a commonly used ionization vacuum gauge, the active gas is adsorbed to the hot filament or the tube wall of the measurement bulb, resulting in large fluctuations in the measured value, especially at 10-4 to 10-3 Torr. In a pressure range of about 100 mL, the response speed becomes slow due to adsorption, and reproducibility also deteriorates, making accurate measurements impossible.

On the other hand, a diaphragm vacuum gauge measures absolute pressure by introducing gas into a high vacuum area through a diaphragm, but it cannot measure when the gas pressure is extremely low. In this case, the diaphragm corrodes, resulting in a shortened service life. The present invention solves the conventional drawbacks and provides a device that can measure the pressure of active gas over a wide range and with good reproducibility.One embodiment of the present invention will be described below with reference to the drawings.

1 is a helium (H
e) A primary ion generating unit that ionizes an inert gas such as argon (Ar).

Reference numeral 3 denotes a primary ion focusing section which extracts primary ions generated from the primary ion generating section and focuses them into an ion beam, and is composed of an Einzel lens 4 and an electrostatic quadrupole lens 5.

Reference numeral 6 denotes a target to be irradiated with the ion beam, which is a metal plate made of silicon (Si), titanium (Ti), etc. attached to the 12 surfaces of the holder T having a dodecagonal cross section.

This holder T can be rotated from the outside of the measuring device main body 2 via a rotating shaft 8, and the target 6 made of various metals can be arbitrarily selected and placed opposite to the ion beam. Further, since the part to be measured 9 is connected to the lower part of the measuring device main body 2, the holder 7 and the target 6 are in an active gas atmosphere. 10 is target 6
A secondary ion measuring section is installed near the ion beam, and the secondary ion intensity is measured by the amount of current using a box of Farade.

Reference numeral 11 denotes a target cleaning section using two sets of parallel plate electrodes, which is disposed between the ion focusing section 3 and the target 6.

When irradiating the target 6 with an ion beam, this target cleaning section 11 cleans the ion beam onto the surface of the target 6 in advance, since if the surface of the target 6 is contaminated due to oxidation etc., this will greatly affect the intensity of the secondary ions generated. Scan, irradiate, and clean. 12 is an exhaust path connected to a diffusion pump (not shown) or the like.

A slit 13 is provided between the primary ion generating section 1 and the primary ion focusing section 3, a slit 14 is provided between the primary ion focusing section 3 and the target cleaning section 11, and a slit 14 is provided between the target 6 and the secondary ion measuring section 10. A slit 15 is provided in each, and the primary ion focusing section 3 and the secondary ion measuring section 10 are differentially pumped. This is because as the active gas gradually enters the primary ion focusing section 3 or the secondary ion measuring section 10, the mean free path of ions becomes shorter, resulting in poor secondary ion generation efficiency and measurement errors. Therefore, by evacuating with a pump, the pressure is always kept lower than the active gas pressure to prevent adverse effects.

The primary ions of the inert gas generated by the primary ion generating section 1 are extracted to the primary ion focusing section 3 and converged to form an ion beam. Ion beam hits target 6 in active gas
When irradiated with , secondary ions are generated, and the secondary ion intensity is measured by the secondary ion measuring section 10 . When the intensity of the ion beam is constant, the intensity of the secondary ions is
The value varies depending on the material, type of active gas, and partial pressure of active gas. If the type of active gas in the part to be measured 9 and the material of the target 6 are specified and the secondary ion intensity is measured as described above, the partial pressure of the active gas can be determined. FIG. 2 shows the relationship between the active gas partial pressure and the secondary ion strength for each material of the target 6, in the case where the active gas is oxygen (02).

Here, argon (Ar) is used as an inert gas for primary ions, and the target 6 is accelerated at 12 KV and irradiated with silicon (Si), titanium (Ti), and indium (I).
n), magnesium (Mg), cobalt (CO), molybdenum (MO), copper (Cu), germanium (Ge),
Silver (Ag), tin (Sn), and cadmium (Cd) were used. In Figure 2, for each metal, there is a part where the secondary ion strength increases linearly as the oxygen partial pressure increases, and if the part where the increase is large is used, the measured secondary ion strength Accurate pressure values can be easily obtained from For example, if the target 6 is titanium (Ti), it is 10-7 to 3×10-6T0rr(02), or silicon (
Si) is 10-6 to 3×10-5T0rr(02),
Indium (In): 10-6 to 2×10-4T0r
r(02), 10-6 to 10- for cadmium (Cd)
Suitable for pressure ranges such as 8T0rr(02).
In the above embodiment, the holder 7 is equipped with a large number of targets 6.
By rotating and selecting an appropriate metal, active gas partial pressure can be easily measured over a wide range. It is also equipped with a target cleaning section 11 that scans and irradiates the surface of the target 6 with an ion beam, and also has a primary ion focusing section 3 and a secondary ion measuring section 10 that are differentially pumped.
Since the active gas partial pressure of the active gas is lowered, the secondary ion intensity relative to the gas partial pressure to be measured can be accurately measured. Here, a box of Farade was used in the secondary ion measurement section 10, but when similarly measuring the amount of current, even higher sensitivity measurement is possible by using an electron multiplier. Further, since it is possible to use a measuring device other than the current amount, the secondary ion intensity in FIG. 2 is expressed in arbitrary units. Furthermore, the target information section 11 consists of two sets of parallel plate electrodes, which scan the ion beam over the surface of the target 6, which allows the irradiation direction of the ion beam to be significantly deflected by a small voltage applied between the electrodes. This is because the surface of the target 6 can be scanned widely or narrowly and can be cleaned. As described above, the present invention includes a primary ion generating section that uses an inert gas as a primary ion species, and a target that is placed in opposition to the primary ion generating section within the main body of the measuring device, which is connected to an active gas measurement target section. a target selection device having a plurality of targets held in an active gas; a primary ion convergence unit provided between the primary ion generation unit and the target; a target cleaning unit provided near the target; The structure includes a secondary ion measuring section and an exhaust system communicating with the primary ion converging section and the secondary ion measuring section, making it easy to measure active gas partial pressures over a wide range by appropriately selecting a target. The present invention provides an active gas partial pressure measuring device with high industrial value, such as extremely high measurement accuracy and long life due to its target cleaning function and exhaust system.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the essential parts of an embodiment of the active gas partial pressure measuring device of the present invention, and FIG. 2 is a relationship diagram showing the secondary ion strength with respect to the oxygen partial pressure of various metals. DESCRIPTION OF SYMBOLS 1...Primary ion generation part, 2...Measurement device main body, 3...Primary ion convergence part, 6...
...Target, 7...Holder, 9...
...Measurement part, 10...Secondary ion measurement part, 1
1...Target clean section, 12...Exhaust path.

Claims (1)

[Scope of Claims] 1. Inside the main body of the measuring device, which is connected to a primary ion generating unit that uses an inert gas as a primary ion species and a part to be measured for active gas partial pressure, a target is placed opposite to the primary ion generating unit. a target selection device including a plurality of targets held in an active gas, a primary ion convergence unit provided between the primary ion generation unit and the target, and a target cleaning unit provided near the target. What is claimed is: 1. An active gas partial pressure measuring device comprising: a primary ion focusing section and a secondary ion measuring section; and an exhaust system communicating with the primary ion focusing section and the secondary ion measuring section. 2. The active gas partial pressure measuring device according to claim 1, wherein the target cleaning section is a parallel plate electrode provided between the primary ion focusing section and the target.