JPH10332686A - Method for inspecting particle of ceramic product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine the amount of particle by applying a solvent to a surface to be inspected, bringing a film made of a soluble material to the surface to be inspected, releasing the film from the surface to be inspected, and analyzing the element of the contacting surface of the film. SOLUTION: When the particle of an electrostatic chuck is to be inspected, methyl acetate is applied to the surface to be inspected of a sample, and a film that is approximately 30 μm thick and is made of acetyl cellulose is overlapped on it and is left in a room for approximately three minutes for adhesion. Then, the film is released from the sample and is applied to the sample stand of a scanning-type electron microscope so that a contacting surface for the surface to be inspected of the film can be observed. In that case, to avoid the charge-up due to the scanning-type electron microscope, a gold sputter film that is approximately 150 Å in thickness is formed on the contact surface and the element on the contact surface of the film is analyzed by an energy dispersion type spectrochemical analyzer that is placed on the scanning type electron microscope, thus determining the particle also for a non-mirror surface and a curved surface by this method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting particles of a ceramic product.

[0002]

2. Description of the Related Art At present, semiconductor wafer transfer, exposure, C
2. Description of the Related Art An electrostatic chuck is used to adsorb and hold a semiconductor wafer in processes such as a film forming process such as VD and sputtering, fine processing, cleaning, etching, and dicing. In a semiconductor manufacturing apparatus, it is necessary to prevent generation of so-called particles that cause semiconductor defects. In an actual semiconductor manufacturing apparatus, the back surface of a semiconductor wafer is attracted and held by an electrostatic chuck. At this time, particles are generated on the back surface side of the semiconductor wafer. If the amount of generated particles is large, the particles may spread to the surface side of the semiconductor wafer or into the chamber, contaminate the chamber, and cause semiconductor defects on the surface of another semiconductor wafer. The same applies to various ceramic semiconductor manufacturing products other than the electrostatic chuck.

[0003] As a conventional method, the surface of an electrostatic chuck is mirror-finished, a silicon wafer is pressed against the mirror surface with a constant load, and the number of particles adhering to the silicon wafer is measured (Japanese Patent Laid-Open No. Hei 7 (1999)). -245336
No.)

[0004]

Although such an inspection method can be applied to a mirror-finished flat surface, it cannot be generally applied to a semiconductor manufacturing product. For example, attached at a position surrounding the outer periphery of the electrostatic chuck,
Products called so-called "rings" are known. Since the ring does not directly contact the semiconductor wafer,
Since no mirror surface is required, and mirror processing is very expensive, mirror processing is not performed.

It has been found that the above-described particle inspection method cannot be applied to products that have not been subjected to such mirror finishing. This is because even if the silicon wafer is to be brought into contact with the surface of the ring, the surface of the ring does not come into surface contact with the silicon wafer, but only makes point contact. As a result, the particles do not adhere to the silicon wafer. In addition, during the point contact between the silicon wafer and the surface of the ring, the silicon wafer itself is shaved and particles are generated.

[0006] Some semiconductor manufacturing products have an annular shape in addition to a cylindrical shape such as a ring.
It was impossible to bring the silicon wafer into contact with the surface of such an irregularly shaped product, for example, the inner surface of a cylindrical product or an annular product, and thus it was impossible to inspect particles. .

An object of the present invention is to provide a new method for quantifying the amount of particles in ceramic products used for applications that dislike particles, such as semiconductor manufacturing products. It is an object of the present invention to enable particles to be quantified even on a curved surface that cannot be brought into contact with an object or a non-mirror surface that has not been mirror-finished at high cost.

[0008]

The inventor of the present invention has been studying a method of inspecting particles present on a surface of a ceramic product to be inspected. In this process, a solvent is applied to the surface of the ceramic product to be inspected. Then, a film made of a material soluble in the solvent is brought into contact with the surface to be inspected, the film is peeled off from the surface to be inspected, and the particles are quantified by performing elemental analysis on the contact surface that was in contact with the surface to be inspected of the film. I thought of it.

When a solvent is applied to the surface to be inspected of a ceramic product and then a film made of a material soluble in the solvent is brought into contact with the surface to be inspected, the solvent melts the contact portion of the film with the surface to be inspected, and Following irregularities in the form of a surface. Particles present on the surface to be inspected are wrapped in the melted portion of the film. And
When the film is peeled off from the surface to be inspected, particles are fixed at a fixed rate on the contact surface side of the film.

Then, the particles are quantified by performing elemental analysis on the contact surface that has been in contact with the surface to be inspected of the film.

The method of the present invention is sufficiently effective even when the surface to be inspected of a ceramic product is not mirror-finished, and the film accurately reflects the amount of particles present in the fine irregularities on the surface to be inspected. I understood. Further, even when the surface to be inspected is a curved surface, the film can be brought into contact with the curved surface so as to follow the shape of the curved surface.

In the present invention, the combination of the film and the solvent is not particularly limited. For example, it is particularly preferable that the material of the film is acetyl cellulose and the solvent is methyl acetate.

The elemental analysis of the contact surface of the film is preferably performed by an energy dispersive spectrometer or a wavelength dispersive spectrometer.

According to the inspection method of the present invention, a ceramic product can be classified into an acceptable product and a defective product according to the intended use. Specifically, a set value is obtained by quantifying the existing ceramic product suitable for the use by the inspection method. Next, measured values obtained by quantifying the particles of each manufactured ceramic product by the above-described inspection method are compared with set values.

The present invention provides, for example, a susceptor for mounting a semiconductor wafer, a dummy wafer, a shadow ring, a tube for generating high-frequency plasma, a dome for generating high-frequency plasma, a high-frequency transmission window,
Infrared transmission window, lift pin for supporting semiconductor wafer, shower plate, electrostatic chuck, vacuum chuck, product with high-frequency electrode for generating plasma embedded in ceramic base, resistance heating element embedded in ceramic base It can be adopted as a method for inspecting particles of various semiconductor manufacturing apparatuses such as products.

Examples of the material of the ceramic product include alumina, aluminum nitride, silicon nitride, and silicon carbide.

[0017]

EXAMPLES [Experiment A] First, experimental results in which the present invention is applied to inspection of particles of an electrostatic chuck will be described.

(Manufacture of Electrostatic Chuck) A wire mesh made of molybdenum was used as an electrostatic chuck electrode. The wire mesh used was a wire mesh in which molybdenum wires having a diameter of 0.12 mm were knitted at a density of 50 wires per inch. A disc-shaped preform was manufactured by uniaxially pressing the aluminum nitride powder, and the wire mesh was embedded in the preform.

The preform was set in a mold, sealed in a carbon foil, and heated at a temperature of 1950 ° C., 200 kg /
The preformed body was fired by a hot press method at a pressure of cm ² and a holding time of 2 hours to obtain a sintered body.
The relative density of this sintered body was 98.0% or more. The diameter of the obtained electrostatic chuck was 200 mm, and the thickness was 8 mm.

(Manufacture of Sample 1 and Measurement of Particles by Conventional Method) After the electrostatic chuck was manufactured as described above, the electrostatic chuck was set on a copper kemet platen, and diamond abrasive grains having an average particle diameter of 6 μm were prepared. Wrap using
Lapping was performed using diamond abrasive grains having an average particle size of 3 μm. Furthermore, the electrostatic chuck was set on a pure tin platen, and lapping was performed using diamond abrasive grains having an average particle size of 0.5 μm. Ra of this machined surface is 0.008 μm
Met.

In a class 1000 clean room,
This adsorption surface was brushed in ultrapure water for 5 minutes using a roll brush made of polyurethane resin. Next, the electrostatic chuck is placed in a clean oven,
It was dried with hot air at 130 ° C. and cooled.

Using this electrostatic chuck, the number of particles was measured. Specifically, in the atmosphere, 200 ℃
Then, the mirror side of the silicon wafer was sucked to the suction surface of the electrostatic chuck, and then the suction was released. The number of particles having a particle diameter of 0.2 μm or more adhering to the mirror side of the silicon wafer was measured using a light scattering type particle counter. This measurement result is 16 pieces / cm ²
Met.

(Manufacture of Sample 2 and Measurement of Particles by Conventional Method) After the electrostatic chuck was manufactured as described above, the electrostatic chuck was set on a copper kemet platen, and diamond abrasive grains having an average particle diameter of 6 μm were prepared. Wrap using
Lapping was performed using diamond abrasive grains having an average particle size of 3 μm. Furthermore, the electrostatic chuck was set on a pure tin platen, and lapping was performed using diamond abrasive grains having an average particle size of 0.5 μm. Ra of this machined surface is 0.008 μm
Met.

In a class 1000 clean room,
This adsorption surface was brushed in ultrapure water for 5 minutes using a roll brush made of polyurethane resin. Next, this electrostatic chuck is immersed in ultrapure water,
Ultrasonic cleaning was performed at 25 ° C. for 5 minutes at a frequency of 30 kHz and an ultrasonic output of 3.7 W / cm ² . Next, the electrostatic chuck was dried with hot air at 130 ° C. in a clean oven and cooled.

Using this electrostatic chuck, the number of particles was measured in the same manner as in Sample 1. The measurement result was 2 / cm ² .

(Production of Sample 3 and Measurement of Particles by Conventional Method) After producing the electrostatic chuck as described above, the electrostatic chuck was placed on a copper kemet platen, and diamond abrasive grains having an average particle diameter of 6 μm were used. Lapping, average particle size 3
Lapping was performed using diamond abrasive grains of μm. The center line average surface roughness Ra of the processed surface was measured by a surface roughness meter and found to be 0.080 μm.

This adsorbed surface was brushed in ultrapure water using a roll brush made of polyurethane resin for 5 minutes in a class 1000 clean room.
Next, this electrostatic chuck was immersed in ultrapure water,
Hz and an ultrasonic output of 3.7 W / cm ² , 5
Ultrasonic cleaning for 25 minutes at 25 ° C. Next, the electrostatic chuck was dried with hot air at 130 ° C. in a clean oven and cooled.

Using this electrostatic chuck, the number of particles was measured in the same manner as in Sample 1. The measurement result was 9 / cm ² .

(Quantification of Particles by the Inspection Method of the Present Invention) Methyl acetate is applied to each of the surfaces to be inspected of Samples 1 to 3, and a 30 μm-thick film made of acetyl cellulose is overlaid thereon. Left for 3 minutes at room temperature. Next, the film was peeled from each sample, and the film was mounted on a sample stage of a scanning electron microscope so that the contact surface of the film with the surface to be inspected could be observed. To avoid charge-up during observation with a scanning electron microscope,
After a 50 angstrom gold sputtered film was formed on the contact surface, the contact surface of the film was subjected to elemental analysis by an energy dispersive spectrometer (EDS) mounted on a scanning electron microscope.

As a result, in the film peeled off from sample 1, the peak intensity ratio of aluminum / gold was 0.0
6, and in the film peeled off from Sample 2,
The aluminum / gold peak intensity ratio was 0.01, and in the film peeled from Sample 3, the aluminum / gold peak intensity ratio was 0.04. FIG. 1 shows the relationship between the measurement result of the number of particles by the light scattering method and the peak intensity ratio of aluminum / gold measured by the inspection method of the present invention.

As can be seen from FIG. 1, there was a very good correlation between the measurement result of the number of particles by the light scattering method and the peak intensity ratio of aluminum / gold measured by the inspection method of the present invention. .

Next, each of the electrostatic chucks of samples 1 to 3 was
Sample 1 as a result of application to D (chemical vapor deposition) process
Yield is 30%, sample 2 is 90%,
In sample 3, it was 50%. Thus, there was also a clear correlation between the particle quantification result according to the present invention and the yield. From this result, the target value of the yield is, for example, 50%
In the case where the above is set, the yield of this target value can be achieved by making the electrostatic chuck having a peak intensity ratio of aluminum / gold of 0.04 or less as acceptable.

[Experiment B] The inspection method of the present invention was applied to a product called a "ring" which is attached at a position surrounding the outer periphery of the electrostatic chuck.

(Manufacture of Ring) A ring 2 schematically shown in FIGS. 2A to 2C was manufactured. However, in FIG. 2A, the semiconductor wafer 4 is set on the suction support device 5. The suction support device 5 includes a support table 5a and an electrostatic chuck 5b. Reference numeral 2 denotes a ring made of alumina, and a semiconductor wafer 4 is set in an inner space 7 of the ring 2.

By pressing the alumina powder under uniaxial pressure, an annular shaped body as shown in FIGS. 2A to 2C was manufactured, and the shaped body was fired at a temperature of 1650 ° C. to obtain a ring. The relative density of the rings was greater than 98.0%. The outer diameter of the ring was 320 mm, the inner diameter was 260 mm, and the thickness was 50 mm.

This ring is immersed in ultrapure water,
Ultrasonic cleaning was performed at 25 ° C. for 5 minutes at a frequency of z and an ultrasonic output of 3.7 W / cm ² . Then, the ring was dried with hot air at 130 ° C. in a clean oven and cooled to obtain Sample 4. Alternatively, the ring was heat-treated at 1400 ° C. for 1 hour to obtain Sample 5. Alternatively, the ring was heat-treated at 1500 ° C. for 1 hour to obtain Sample 6.

In this embodiment, the inner surface 2 of the ring 2
a was set as the surface to be inspected. Methyl acetate was applied to each inner surface 2a of each ring 2. A film made of acetyl cellulose having a size of 10 mm × 10 mm and a thickness of 30 μm was overlaid on two or three portions of each inner surface 2 a and left at room temperature for 3 minutes.
Next, each film was peeled from the ring, and the film was attached to a sample stage of a scanning electron microscope so that the contact surface of the film with the ring could be observed. In order to avoid charge-up during observation with a scanning electron microscope, a gold sputtered film having a thickness of 150 Å was formed on the contact surface of the film. Elemental analysis of the contact surface of the film was performed by an energy dispersive spectrometer mounted on a scanning electron microscope.

As a result, the peak intensity ratio of aluminum / gold was 0.12 for sample 4 and 0.05 for sample 5.
And in Sample 6, it was 0.01.

Also, as a result of replacing the rings in the apparatus used for a long time in the CVD process and constantly achieving a yield of 90% or more with the rings of samples 4 to 6, the yields were 30% and 70%, respectively.
%, 90%. FIG. 3 shows the relationship between the peak intensity ratio of aluminum / gold and the yield in the CVD process.

As can be seen from this graph, there was a clear linear relationship between the two. In other words, from this result, when the target value of the yield is set to, for example, 50% or more, a ring having a peak intensity ratio of aluminum / gold of 0.08 or less is regarded as an acceptable product, so that the yield of the target value is obtained. Can be achieved.

[0041]

As is apparent from the above, according to the present invention, a new method for quantifying the amount of particles in ceramic products used for applications that dislike particles, such as semiconductor manufacturing products, is provided. Could be provided. Moreover, this method can quantify particles even on non-mirror surfaces and curved surfaces.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an aluminum / gold peak intensity ratio and the number of particles measured by a light scattering method in Experiment A.

FIG. 2A is a partial cross-sectional view schematically showing a state where a ring is installed at a position surrounding an outer periphery of an electrostatic chuck;
(B) is a side view of the ring, and (c) is a plan view of the ring.

FIG. 3 is a graph showing a relationship between a peak intensity ratio of aluminum / gold and a yield in a CVD process in Experiment B.

[Explanation of symbols]

2, ring 4, semiconductor wafer 5, wafer suction support 5b, electrostatic chuck

Claims (6)

[Claims] 1. A method for inspecting particles present on a surface to be inspected of a ceramic product, wherein a solvent is applied to the surface to be inspected of the ceramic product, and a film made of a material soluble in the solvent is then inspected. Contact the surface,
Inspection of particles of a ceramic product, wherein the film is peeled off from the surface to be inspected, and the particles are quantified by performing elemental analysis of a contact surface of the film that has been in contact with the surface to be inspected. Method. 2. The method according to claim 1, wherein the material of the film is acetyl cellulose, and the solvent is methyl acetate. 3. The method according to claim 1, wherein the elemental analysis is performed by an energy dispersive spectrometer or a wavelength dispersive spectrometer. 4. The ceramic product inspection according to claim 1, wherein the particles are inspected without mirror-finishing the surface to be inspected of the ceramic product. Method. 5. The apparatus according to claim 1, wherein the surface to be inspected is a curved surface, and the film is brought into contact with the curved surface so as to follow the shape of the curved surface. An inspection method of a ceramic product according to one claim. 6. When inspecting particles of a ceramic product in order to classify the ceramic product into an acceptable product and a defective product according to a target application, an existing ceramic product suitable for the application is used. Claim 1
A set value is obtained by quantifying the ceramic product according to the method for inspecting particles of the ceramic product according to claim 1, and the measured value obtained by quantifying the manufactured ceramic product by the method for inspecting particles of the ceramic product according to claim 1 is the set value. The method for inspecting particles of a ceramic product according to claim 1, wherein the acceptable product and the defective product are separated by comparing with the above.