JP3055645B2 - Suction type particle measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sucking a part of gas or liquid in which fine particles are suspended, and measuring the number, the particle size, etc. of the fine particles in the sucked sample. In particular, the present invention relates to a method for efficiently suction-measuring particles floating in a space at a different potential with respect to the surroundings and charged particles floating.

[0002]

2. Description of the Related Art In the process of manufacturing a semiconductor integrated circuit, fine particles adhere to the surface of the semiconductor integrated circuit, thereby causing defects in the circuit and reducing the product yield. Therefore, it is necessary to detect the size and the number of fine particles in a predetermined system such as a processing chamber.

As a method for detecting such fine particles, a suction-type fine particle measuring method disclosed in Japanese Utility Model Publication No. 5-14198 has been conventionally known. This suction-type particle measurement method was premised on being used under normal pressure.

[0004]

The CVD and etching steps in the semiconductor integrated circuit manufacturing process are performed in a plasma atmosphere. In general, the potential in the plasma region creates an ion sheath (region with a large amount of positive ions) around it, so that it is positive with respect to the surroundings, and negatively charged fine particles are confined in the plasma region. for that reason,
Since the periphery of the plasma region is a relatively negative region, as shown in FIG. 5, there is a potential wall between the microparticles and the probe, so that it is difficult to suck. In particular, the semiconductor integrated circuit manufacturing process is often performed in a reduced-pressure atmosphere including the CVD and etching steps, and it is originally difficult to suck. Thus, the conventional suction-type fine particle measurement method has a limit in accurate measurement.

[0005]

In order to solve the above-mentioned problems, the present application suctions a sample from a system containing charged fine particles via a probe, introduces the sample into a fine particle detection device, and counts the number of fine particles in the system. The first invention is based on the premise that the method is a suction-type fine particle measuring method for detecting the particle size and the particle size.
A state in which the probe is charged to the opposite sign to the charge of the fine particles,
Switch to a state charged to the same sign to perform suction
I did .

In the second invention, the probe is finely divided.
Charged to the opposite sign to the charge of the element and charged to the same sign
So that suction is performed while continuously changing between
Was .

[0007]

[Function] The probe is charged to the opposite sign to the charge of the fine particles.
State and charged state with the same sign.
To the same sign as the charge
Continuous change between charged state
Thus, the fine particles can be electrically taken into the probe.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a view showing a state in which a suction type particle measuring method which is a premise of the present invention is applied to a plasma processing chamber, FIG. 2 is an enlarged view of a main part of FIG. 1 , and FIG.
FIG. 4 is a diagram illustrating a suction-type particle measuring method, and FIG.
FIG. 3 is a diagram illustrating such a suction-type particle measurement method .

FIG . 1 shows a suction type fine particle as a premise of the present invention.
Shows the measurement method applied to the plasma processing chamber.
In the figure , reference numeral 1 denotes a plasma processing chamber. The plasma processing chamber 1 is fixed on a base 2, and the base 2 is provided with a vertically movable table 3 facing the inside of the chamber 1. A semiconductor wafer W is placed on the substrate.

A reaction gas introduction pipe 4 is attached to the upper part of the chamber 1, and an electrode 5 is provided inside the chamber 1.
Is arranged, and a suction type particle measuring device 10 is attached to the side surface of the chamber 1.

The suction type particle measuring apparatus 10 allows a first probe 12 to penetrate the side surface of the chamber 1 via an insulator 11, and connects a second probe 14 to the first probe 12 via an insulator 13. And the second probe 14
Is introduced into the light scattering type fine particle meter 15, and the probe 14 derived from the light scattering type fine particle meter 15 is connected to a suction device (not shown).

The light scattering type fine particle meter 15 includes a transparent cell 16 through which a sucked sample flows, and a light source 1 for generating a laser beam.
7, an optical system 18 for irradiating the sample flowing with the laser beam to the cell 16, and a photoelectric conversion element 20 for receiving the laser beam scattered by the fine particles in the sample via the optical system 19. The number and the particle size of the fine particles are displayed on a monitor or the like based on the signal of the above. In addition, the fine particle meter 15 is not limited to the light scattering type, but may be a light transmission method, an inertia method,
Various devices using a known method such as a diffusion method can be applied.

On the other hand, a potential is applied to the first probe 12 which is electrically insulated from other members via the insulator 13 via a power supply line 21. For example, as shown in FIG. 2, when measuring the negatively charged fine particles 31 in the plasma region 30, the charge of the first probe 12 is set to be positive. In other words, a negative charge region is formed outside the positive charge plasma region, and this negative charge region forms a potential gradient that prevents the negative charge particles trapped in the plasma from jumping out. doing.

Therefore, by making the charge of the probe 12 positive,
Moreover, by eliminating the potential difference between the plasma region and the probe 12, that is, by reducing the potential gradient, the fine particles having a negative charge are smoothly attracted to the probe 12, and It is sent to a total of 15. Here, 32 is a positive ion, and 33 is an electron.

FIG. 3 is a view for explaining the suction type particle measuring method according to the present invention. In the present invention, there is no potential barrier between the particles and the probe 12 and the particles 34
Shows a case where the electric charge of the is positive. In this case, by applying an electric potential to the probe 12 and setting the charge of the probe 12 to the opposite sign to the charge of the fine particles, the fine particles can be taken into the probe also by using the electric attraction force.

In the method shown in FIG. 3, the charge of the probe 12 is switched between positive and negative by the switch 22. For example, after the charge of the probe 12 is made negative for a certain period of time and the fine particles are taken in, the switch is turned on. By switching 22, the electric charge of the probe 12 is made positive to positively prevent the capture of fine particles. At this time, there is a flow of gas to the probe 12, but no particles are sucked. This makes it possible to accurately measure fine particles within a certain period of time, and also to perform synchronous measurement with another system.

[0017] FIG. 4 is a diagram illustrating the suction-type particle measuring method according to another invention, by sweeping the potential of the probe 12 from the plus or minus or from minus to plus, the probe of the particulate charge and opposite sign The suction can be performed while continuously changing between the charged state and the charged state. With such a configuration, since the suction efficiency changes depending on the charge distribution of the particles, the charged state of the particles in the measurement region can be known.

[0018]

As described above, according to the first aspect of the present invention, the probe is charged in the opposite sign to the charge of the fine particles.
Suction by switching between the state and the state charged to the same sign
Intentionally shut off the suction of fine particles.
And therefore accurate measurement of fine particles within a certain time
Measurement and synchronous measurement with other systems
Become .

In the second invention, the probe is finely divided.
Charged to the opposite sign to the charge of the element and charged to the same sign
Suction is performed while continuously changing between states
So you can know the charged state of the particles in the measurement area
You .

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which a suction-type particle measuring method, which is a premise of the present invention, is applied to a plasma processing chamber.

FIG. 2 is an enlarged view of a main part of FIG. 1;

FIG. 3 is a diagram illustrating a suction-type particle measuring method according to the present invention.

FIG. 4 is a diagram illustrating a suction-type fine particle measurement method according to another invention.

FIG. 5 is a schematic diagram showing a relationship between charged fine particles and a potential gradient.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Plasma processing chamber, 10 ... Suction type fine particle measuring device, 11, 13 ... Insulator, 12 ... First probe, 1
4: second probe, 15: fine particle meter.

Continuation of the front page (56) References Masao Watanabe, et al., “Particles in Processing Plasma”, Journal of Plasma and Fusion Society, 1993, Vol. 69, No. 7, p. 752-763 Iku Kondo, “Special Issue on Latest Particle Measurement Technology in-situ Particle Monitoring (Dry Process)”, Clean Technology, July 1994, Volume 4, Issue 7, p19-21 (58 ) Fields surveyed (Int. Cl. ⁷ , DB name) G01N 15/00-15/14 G01N 1/22 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A suction type fine particle in which a sample is sucked from a system containing charged fine particles via a probe, and the sample is introduced into a fine particle detecting device to detect the number, particle size, etc. of the fine particles in the system. In the measurement method, the probe was charged to the opposite sign to the charge of the fine particles, and charged to the same sign.
A suction-type fine particle measurement method, wherein suction is performed by switching between states . 2. A suction type fine particle in which a sample is sucked from a system containing charged fine particles via a probe, and the sample is introduced into a fine particle detecting device to detect the number, particle size, etc. of the fine particles in the system. In the measuring method, the probe is
The state charged to the opposite sign to the charge and the state charged to the same sign
Wherein the suction is performed while continuously changing the particle size between the two.