Gas nozzle

Abstract

To provide a gas nozzle having a burnt surface excellent in particle reduction effect.SOLUTION: A gas nozzle 1 according to the present invention is made of a ceramic sintered body having at least one through hole 2a through which gas flows. The gas nozzle 1 includes a first region A in which both the entire inner surface 2a of a through-hole 2 and the end surface 1A provided with the outlet 2b of the through-hole 2 are fired surfaces, and the inner surface 2a of the through-hole 2 is in the vicinity of the outlet 2b, and a second region B located further back than the first region A, and the average crystal grain size in the first region A is smaller than the average crystal grain size in the second region B.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a gas nozzle, and more particularly to a gas nozzle made of a ceramic sintered body that ejects a corrosive gas and is used in an apparatus having a plasma process such as a semiconductor manufacturing apparatus.

Background Art

[0002] As one of the corrosion-resistant members for plasma process apparatuses, there is a gas nozzle provided for introducing an etching gas into a processing apparatus and exposed to a plasma atmosphere. The overall shape of a general gas nozzle is formed in a so-called columnar body. That is, the overall shape of the gas nozzle has a pair of end faces formed in any shape of a circle, an ellipse, or a polygon, and a side face portion having a predetermined length in a direction substantially perpendicular to the pair of end faces. A plurality of through holes through which a gas such as an etching gas flows are formed along the axis of the columnar body in the gas nozzle. Incidentally, as the material of the gas nozzle, a yttria sintered body or an alumina sintered body having excellent corrosion resistance is generally used.

[0003] By the way, one of the technical problems of a gas nozzle made of a ceramic sintered body is particle generation from the gas nozzle, and several countermeasures have been taken to reduce this. As one of the solutions, a technique focusing on the surface state of the inner wall of the gas nozzle is described in Patent Document 1.

[0004] The gas nozzle described in this Patent Document 1 will be described with reference to FIGS. 2 and 3. FIG. 2 is a perspective view schematically showing the gas nozzle, and FIG. 3 is a cross-sectional view taken along line I-I of FIG. 2. The gas nozzle 10 shown in this Patent Document 1 is composed of a columnar main body made of a ceramic sintered body in which a through hole 13 through which a gas flows is formed, and an end face 11 of the main body is formed with an outlet 14 of the gas in the through hole 13.

[0005] Furthermore, as shown in FIG. 3, the inner wall 13a of the through hole 13 of the gas nozzle 10 has a first region A located near the outlet 14 and a second region B located inside the main body rather than the first region A, and the first region A and the second region B are formed on the fired surface of the ceramic sintered body. And the average crystal grain size in the first region A is formed larger than the average crystal grain size in the second region B.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] By the way, Patent Document 1 states that "when the average crystal grain size on the fired surface of the ceramic sintered body is large, the ratio of the area of the grain boundaries on the fired surface that are easily corroded by plasma becomes small, so that when the fired surface is exposed to the plasma - converted gas, particles are less likely to fall off. Therefore, the generation of particles in the first region A that is easily exposed to the plasma - converted gas can be reduced well." That is, Patent Document 1 shows that a larger average crystal grain size near the outlet 14 of the gas nozzle 10 can reduce the amount of particle generation.

[0008] Also, Patent Document 1 states that "when the average crystal grain size on the fired surface of the ceramic sintered body is small, the filling rate of crystal particles on the fired surface becomes high, so that the mechanical strength of the fired surface becomes high. Therefore, by increasing the mechanical strength while reducing the influence of the plasma - converted gas, damage to the main body caused by mechanical stress or thermal stress can be suppressed."

[0009] However, as a result of the verification of the gas nozzle described in Patent Document 1 by the inventors of the present invention, the particle reduction effect was small, and its performance was not necessarily satisfactory. Then, as a result of intensive research by the inventors of the present invention on the average crystal grain size on the fired surface of the ceramic sintered body, it was found that reducing the average crystal grain size of the inner wall surface on the outlet side of the gas nozzle to be smaller than the average crystal grain size of the inner wall surface on the back side is superior in the effect of reducing the amount of particle generation, and the present invention has been completed.

[0010] The present invention has been made in view of the above, and an object thereof is to provide a gas nozzle having a fired surface with a more excellent particle reduction effect.

Means for Solving the Problems

[0011] The present invention has been made to achieve the above object, and the gas nozzle according to the present invention is a columnar gas nozzle made of a ceramic sintered body and having at least one through-hole through which gas flows. In the gas nozzle, the entire inner surface of the through-hole and the end face provided with the outlet of the through-hole are both fired surfaces. The inner surface of the through-hole has a first region A near the outlet and a second region B located further back than the first region A. The distance from the end face of the outlet to the back side in the first region A is within 0.5 mm, and the second region B is on the further back side than the first region A and the distance from the end face of the outlet is within 3 mm. The average crystal grain size in the first region A is smaller than the average crystal grain size in the second region B. Moreover, the average crystal grain size in the second region B is 1.2 times or less of the average crystal grain size in the first region A. It is characterized by this.

[0012] In the gas nozzle according to the present invention, by having the above configuration, in a gas nozzle having a fired surface (fired skin surface), the generation of particles can be effectively suppressed.

Effects of the Invention

[0014] According to the present invention, a gas nozzle having a fired surface (fired skin surface) with a more excellent particle reduction effect can be obtained.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0016] Hereinafter, an embodiment of the gas nozzle according to the present invention will be described with reference to FIG. 1. As shown in FIG. 1, the gas nozzle 1 according to the present invention is a columnar gas nozzle made of a sintered ceramic body having at least one through-hole 2 through which gas flows, similar to the conventional gas nozzle 10. Specifically, the gas nozzle has end faces 1A and 1B that are substantially flat and face each other, and at least one through-hole 2 is provided so as to penetrate these end faces 1A and 1B. An outlet 2b is formed at one end face 1A of the through-hole 2, and an inlet 2c is formed at the other end face 1B.

[0017] That is, the gas nozzle 1 according to the present invention is formed in a columnar shape having end faces 1A and 1B in any shape of a circle, an ellipse, or a polygon, and side faces 1C having a predetermined length dimension extending in a direction perpendicular or oblique to the end faces 1A and 1B. Note that this gas nozzle 1 can be designed by appropriately selecting known shapes and sizes as a gas nozzle for ejecting a corrosive gas used in a plasma processing apparatus.

[0018] This gas nozzle 1 is made of a ceramic having excellent corrosion resistance, and preferably, those mainly composed of yttria can be mentioned. Further, it is more preferable to use a yttria sintered body added with 0.5 to 5 wt% of tantalum oxide as an auxiliary agent. When tantalum oxide is appropriately added to yttria, abnormal growth during firing is suppressed, and the difference in average crystal grain size between the first region A and the second region B can be made within a preferable predetermined range.

[0019] The gas nozzle 1 has a surface in contact with the plasma and the reaction gas formed as a firing surface. The surface in contact with the plasma and the reaction gas corresponds to the entire end face 1A of the gas nozzle 1 and the entire inner wall (inner surface) 2a of the through-hole 2. That is, the gas nozzle 1 has at least the entire inner surface 2a of the through-hole 2 and the end face 1A provided with the outlet 2b of the through-hole 2 both formed as firing surfaces (fired surfaces). Note that, for areas other than the entire inner surface 2a of the through-hole 2 and the end face 1A provided with the outlet 2b of the through-hole 2, either a machined surface or a firing surface may be used. Furthermore, the entire surface of the gas nozzle 1 may be a firing surface.

[0020] Here, the firing surface is a surface that, after firing the ceramics, is not subjected to processing such as polishing or grinding on the fired surface, nor is it subjected to coating or coating treatment, although chemical treatment for controlling cleaning may be appropriately performed. Note that the side surface 1C of the gas nozzle 1 may be a firing surface (fired surface) as described above, or may be subjected to processing such as polishing or grinding on the firing surface (fired surface), or may be subjected to coating or coating treatment.

[0021] Thus, in the gas nozzle 1, both the entire inner surface 2a of the through-hole 2 and the end face 1A provided with the outlet 2b of the through-hole 2 are formed as firing surfaces, and are not subjected to processing such as polishing or grinding on the fired surface, so there is no crushed layer due to processing. Therefore, even when the firing surface is damaged by the plasma, particularly large particles generated by the peeling of the crushed layer are suppressed.

[0022] Furthermore, the inner surface 2a of the through-hole 2 in the gas nozzle 1 has a first region A near the outlet 2b and a second region B located further inside than the first region A, and the average crystal grain size in the first region A is formed smaller than the average crystal grain size in the second region B. As shown in FIG. 1, the first region A and the second region B are regions formed continuously from the outlet 2b of the gas nozzle 1 toward the inside.

[0023] When the average crystal grain size in the first region A is smaller than that in the second region B, the amount of particle generation due to the peeling of crystal particles is suppressed. Although the reason has not been clearly elucidated at present, in region A where the plasma is more likely to strike strongly, the small average crystal grain size increases the strength, enabling it to withstand physical impacts such as radicals during plasma exposure and suppressing the generation of particles. On the other hand, for example, in the gas nozzle of an apparatus for microfabricating an object by supplying a halogen-based corrosive gas as a source gas into the reaction chamber and using it as a plasma-etched gas, in region B where more halogen-based corrosive gas (e.g., fluorine-based gas) contacts than plasma, by increasing the average crystal grain size, the grain boundaries are reduced, making it more resistant to grain boundary corrosion by the halogen-based corrosive gas and suppressing the generation of particles due to corrosion. That is, considering the balance between the actions of plasma and halogen-based corrosive gas (e.g., fluorine-based gas) on the cermet sintered body and the particle size, the relationship of the average crystal grain size as in the present invention is considered to be suitable.

[0024] Here, showing a specific aspect regarding the first region A and the second region, the distance from the outlet to the back side in the first region A is within 0.5 mm, the second region B is further back than the first region A and the distance from the outlet is within 3 mm, and the average crystal grain size in the second region B is 1.2 times or less that in region A. The average particle size in the first region A is, for example, 3 μm to 3.5 μm, and the average particle size in the second region B is, for example, 3.4 μm to 4 μm. These average particle sizes can be obtained by photographing the surfaces of the first region A and the second region B using a scanning electron microscope (SEM) and analyzing this photographed image using an image analysis apparatus (apparatus name: Mac-View).

[0025] The reason for setting the distance of the first region A from the outlet to the back side to be within 0.5 mm is that during firing, this region is easily affected by heating due to heat transfer, and thus the particle size tends to increase, making the difference in particle size from the second region B clear. Also, the reason for setting the second region B to have a distance from the outlet within 3 mm on the back side further than the first region A is that since the heating due to heat transfer in this region proceeds with almost uniform temperature during firing, a substantially constant particle size distribution is obtained. That is, the particle size is stable on the back side including this region, and it can be said that it is a sufficient region to specify as the range where the effect of the present invention can be obtained.

[0026] Furthermore, the reason for setting the average crystal grain size in the second region B to be 1.2 times or less the average crystal grain size in the region A is that within this range, the effect of the present invention is more effectively exerted. That is, when the average crystal grain size in the second region B exceeds 1.2 times the average crystal grain size in the region A, the stress difference between the crystals becomes excessive, which may cause peeling at the boundary (inner wall surface) between the region A and the region B.

[0027] The gas nozzle 1 can be manufactured using a general manufacturing method. For example, first, pure water and an organic binder are added to ceramic powder, and then wet-mixed in a ball mill to prepare a slurry. Then, the slurry is granulated by spray drying to form ceramic granulated powder. And using the ceramic granulated powder, it is formed into a predetermined shape using a molding method such as a die pressing method or a cold isostatic pressing method (CIP molding method) to obtain, for example, a columnar molded body. Next, after drilling a through hole in the molded body, it is fired at, for example, 1400°C or higher and 2000°C or lower in either an air atmosphere or an oxygen atmosphere to obtain the gas nozzle according to the present invention. Since this gas nozzle is not processed after firing, in addition to the entire inner surface 2a of the through hole 2 and the end face 1A provided with the outlet 2b of the through hole 2, other surfaces also have a fired surface finish.

[0028] Here, when firing the molded body with a predetermined shape in a firing furnace after manufacturing it, it is preferable to arrange it so that the heat transfer at the outlet 2b of the gas nozzle 1 is accelerated. Specifically, when placing the green compact on the placement table of the firing furnace, the portion corresponding to the outlet 2b of the gas nozzle 1 of the green compact is placed on the placement table (the portion corresponding to the inlet 2c of the gas nozzle 1 of the green compact is placed facing upward). Thereby, during the firing of the green compact, heat is applied from above (inward from the inlet 2c) of the green compact, and heat escapes from the outlet 2b side to the placement table side. As a result, compared with the first region A located near the outlet 2b, a large amount of heat is more likely to be applied to the second region B located inside the green compact.

[0029] And when the gas nozzle is formed of, for example, a yttria sintered body, a yttrium aluminum garnet sintered body, a spinel sintered body, or a high-purity alumina sintered body, liquid phase sintering occurs when firing the green compact. For this reason, the particle size of the second region B where a large amount of heat is likely to be applied is more likely to grow larger than the particle size of the first region A. As a result, the average crystal grain size in the first region A can be made smaller than the average crystal grain size in the second region B.

[0030] Thus, it is preferable to arrange the outlet 2b of the gas nozzle 1 in the firing furnace to rest on the placement plate. With such a manufacturing method, it is possible to relatively easily achieve an average crystal grain size in the manner of the present invention.

[0031] In addition, for the entire inner surface of the through hole and the end face provided with the outlet of the through hole, machining such as grinding and polishing is not performed. This is to prevent the generation of a crushed layer due to machining, and to suppress particularly large particles generated by the peeling of the crushed layer even when the fired surface is damaged by plasma.

[0032] In this way, the gas nozzle can be manufactured. In particular, as described above, after producing a molded body having a predetermined shape, when firing this molded body in a firing furnace, it is preferable to arrange it so that the heat transfer at the outlet 2b of the gas nozzle 1 when placed in the furnace becomes faster. For example, by arranging the outlet 2b of the gas nozzle 1 in the firing furnace to rest on the placement plate, it is possible to relatively easily achieve an aspect of the average crystal grain size as in the present invention.

Example

[0033] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the examples shown below.

[0034] (Example 1) (Manufacturing conditions - Production of fired body) Yttria powder with a purity of 99.9% or more, pure water, tantalum oxide as an auxiliary agent, and other commercially available organic binders were each weighed and wet-mixed in a ball mill to prepare a slurry. Then, this slurry was granulated by spray drying. The particle size of the granulated powder used was in the range of 17 μm to 40 μm. Using the granulated yttria powder, a cylindrical molded body having a 1.5 mm diameter through-hole formed at the center of the gas nozzle end face was obtained by using the cold isostatic pressing method (CIP molding method). Then, it was degreased at a temperature of 1100 °C or higher in an air atmosphere to decompose the organic binder, and subsequently fired at 1800 °C in a hydrogen atmosphere. Through the above steps, a gas nozzle for evaluation was manufactured.

[0035] As Example 1, the outlet of the gas nozzle was arranged so as to contact the placement plate in the firing furnace. Specifically, the end face 1A of the gas nozzle in FIG. 1 was arranged on the lower side (placement plate side), and the end face 1B was arranged on the upper side. Then, an evaluation gas nozzle was manufactured under the above common manufacturing conditions. At this time, a flange portion was formed on the side face 1C on the end face 1A side so that the end face 1A of the gas nozzle did not directly contact the mounting table, and it was placed on the mounting table using a jig that contacted only this flange portion. That is, a jig (annular shape) made of the same material (yttria) and in the same state (having a fired surface) as the nozzle was prepared, and the flange portion on the end face 1A side was supported by this jig so that the end face 1A did not contact the mounting table. At this time, yttria powder was applied between the flange portion on the end face 1A side and the jig to reduce the contact area. Note that this jig only needs to be able to support the flange portion on the end face 1A side with a very narrow contact area, and its shape is not particularly strictly limited.

[0036] (Comparative Example 1) As Comparative Example 1, the outlet of the gas nozzle was arranged so as to face the side opposite to the placement plate in the firing furnace. That is, it was arranged upside down compared to the case of Example 1, with the end face 1A of the gas nozzle on the upper side and the end face 1B on the lower side. Then, an evaluation gas nozzle was manufactured under the same manufacturing conditions as in Example 1 above.

[0037] (Evaluation 1: Average crystal grain size) For Example 1 and Comparative Example 1, the average crystal grain size of the inner wall surface of the through-hole was measured from the gas nozzle outlet (end face portion) toward the inner side of the gas nozzle. The measurement points were measured every 0.5 mm with the gas nozzle outlet as zero. The first region A was the average of the values measured at two points of 0 mm and 0.5 mm, and the second region B was the average of the values measured at three points of 1.0 mm, 1.5 mm, and 2 mm. For the measurement, a non-contact scanning electron microscope (SEM) was used to obtain an image of the inner wall surface, and the number of particles and the average crystal grain size were obtained by image analysis.

[0038] (Evaluation 2: Particle generation amount) For Example 1 and Comparative Example 1, a chamber of a known ICP etching apparatus was used, and a corrosion test was conducted for 12 hours using CF4 plasma. Then, the amount of generated particles was measured using a similarly known airborne particle counter. Note that the amount of generated particles was measured as the increase in the number of particles with a diameter of 2 μm or more before and after the corrosion test in a 1 mm□ area on an arbitrary surface of the gas nozzle (unit: pts: pieces / cm 2 ).

[0039] In the above Evaluation 1 and Evaluation 2, in Example 1, the average crystal grain size of the first region A was 3.3 μm, the average crystal grain size of the second region B was 3.9 μm, the ratio of the average crystal grain size of the second region B to the first region A was 1.18, and the amount of generated particles was 1000 pts.

[0040] Also, in Evaluation 1 and Evaluation 2, in Comparative Example 1, the average crystal grain size of the first region A was 5.8 μm, the average crystal grain size of the second region B was 5.2 μm, the ratio of the average crystal grain size of region B to region A was 0.9, and the amount of generated particles was 2000 pts.

[0041] As described above, when the average crystal grain size of the first region A is smaller than the average crystal grain size of the second region B, it was confirmed that the amount of generated particles is less than when the average crystal grain size of the first region A is larger than the average crystal grain size of the second region B. And the ratio of the average crystal grain size of the second region B to the first region A at that time was 1.18, that is, 1.2 times or less.

[0042] (Example 2) As is clear from the results of Example 1 above, in the present invention, it is more preferable that the first region A is within 0.5 mm from the end face of the gas nozzle outlet toward the back side, and the second region B is within 3 mm from the end face of the gas nozzle outlet on the back side further than the first region A. Regarding the distance from the end face of the outlet of the first region A toward the back side, it can be adjusted, for example, at the temperature during firing. Therefore, in Example 2, the firing temperature was adjusted, and for the first region A, the gas nozzle was fired and formed so that the distance from the end face of the gas nozzle outlet toward the back side exceeded 0.5 mm and was within 1 mm.

[0043] In addition, the firing temperature in the actual production of the gas nozzle is determined in consideration of the density of the entire gas nozzle, the uniformity of the particle size distribution, the occurrence of cracks during firing, etc. In Example 2, however, only the firing temperature was intentionally changed for the purpose of verifying the effects of the present invention. Also, the distance from the end face of the gas nozzle outlet in the second region B is defined for specifying the first region A and depends on the distance from the end face of the gas nozzle outlet in the first region A. Therefore, in the present invention, only the distance from the end face of the outlet in the second region B is not independently controlled.

[0044] In this Example 2, as described above, for the region of the first region A, the firing temperature was set to 1700°C, which is lower than that in Example 1 (1800°C), so that the distance from the end face of the gas nozzle outlet toward the back side exceeded 0.5 mm and was within 1 mm. Other conditions were the same as in Example 1 for production and evaluation.

[0045] (Evaluation 1: Average crystal grain size) Regarding Example 2, from the gas nozzle outlet (end face portion), toward the back side of the gas nozzle, the average crystal grain size of the inner wall surface of the through hole was measured. The measurement positions were measured every 0.5 mm with the gas nozzle outlet as zero. The values measured at three positions of 0 mm, 0.5 mm, and 1.0 mm in the first region A and two positions of 1.5 mm and 2 mm in the second region B were averaged. For the measurement, a non-contact scanning electron microscope (SEM) was used to acquire an image of the inner wall surface, and the number of particles and the average crystal grain size were obtained by image analysis.

[0046] (Evaluation 2: Particle generation amount) Regarding Example 2, the chamber of a known ICP etching apparatus was used, and a 12-hour corrosion test was conducted using CF4 plasma. Subsequently, the generation amount of particles was measured using a similarly known airborne particle counter.

[0047] In the above Evaluation 1, in Example 2, the average crystal grain size in the first region A was 3.0 μm, the average crystal grain size in the second region B was 3.4 μm, and the ratio of the average crystal grain size of the second region B to the first region A was 1.14.

[0048] Also, in Evaluation 2, the particle generation amount was 1500 pts. This is because in Example 2, since the distance from the outlet end face of the gas nozzle in the first region A to the back side of the nozzle exceeded 0.5 mm, the area of the first region A with a small average crystal grain size relatively increased compared to Example 1. As a result, the area of the first region A, which is more vulnerable to grain boundary corrosion by the halogen-based corrosive gas than the area of the second region B, increased. Therefore, it is considered that the particle generation amount increased compared to Example 1.

[0049] (Example 3) Regarding the influence of the ratio of the average crystal grain size of the second region B to the first region A on the particle generation amount, it can be adjusted by selecting and using jigs with different heights (the distance from the end face 1A to the surface of the mounting table). Therefore, in Example 3, only the height of the jig (the distance from the end face 1A to the surface of the mounting table) was changed with respect to the conditions of Example 1, and the influence on the particle generation amount was verified.

[0050] The height of the jig used in Example 1 was 30 mm. In contrast, in Example 3, a jig with a height of 10 mm was used. The gas nozzle was manufactured in the same manner as in Example 1 under other conditions, and the same Evaluations 1 and 2 as in Example 1 were conducted.

[0051] For the gas nozzle manufactured in Example 3, regarding the first region A as in Example 1, the distance from the end face of the gas nozzle outlet toward the inner side of the gas nozzle was within 0.5 mm, and regarding the second region B, the distance from the end face of the gas nozzle outlet toward the inner side of the gas nozzle was within 3 mm.

[0052] (Evaluation 1: Average crystal grain size) For Example 3, the average crystal grain size of the inner wall surface of the through hole was measured from the gas nozzle outlet (end face portion) toward the inner side of the gas nozzle. The measurement positions were measured every 0.5 mm with the gas nozzle outlet as zero. The values measured at two positions of 0 mm and 0.5 mm in the first region A and the values measured at three positions of 1.0 mm, 1.5 mm, and 2 mm in the second region B were averaged. For the measurement, an image of the inner wall surface was acquired using a non-contact scanning electron microscope (SEM), and the number of particles and the average crystal grain size were obtained by image analysis.

[0053] (Evaluation 2: Particle generation amount) For Example 3, the chamber of a known ICP etching apparatus was used, and a corrosion test was performed for 12 hours with CF4 plasma. Then, the generation amount of particles was measured using a known airborne particle counter.

[0054] In the above Evaluation 1, in Example 3, the average crystal grain size in the first region A was 3.9 μm, the average crystal grain size in the second region B was 4.0 μm, and the ratio of the average crystal grain size in the second region B / the first region A was 1.02 (corresponding to the lower limit of a more preferable range of the present invention).

[0055] Also, in Evaluation 2, the particle generation amount was 1300 pts. The results of this Example 3 are inferior to those of Example 1, but the particle generation amount is sufficiently low compared with Comparative Example 1, and it can be said that the effects of the present invention are obtained.

[0056] (Example 4) In Example 4, with respect to the conditions of Example 1, only the height of the jig (the distance from the end face 1A to the surface of the mounting table) was changed to verify the influence on the particle generation amount. The height of the jig used in Example 1 was 30 mm, but in Example 4, a jig with a height of 50 mm was used. The gas nozzles were manufactured under the same conditions as in Example 1, and the same evaluations 1 and 2 as in Example 1 were performed.

[0057] For the gas nozzle manufactured in Example 4, with respect to the first region A as in Example 1, the distance from the end face of the gas nozzle outlet toward the inner side of the gas nozzle was within 0.5 mm, and for the second region B, the distance from the end face of the gas nozzle outlet toward the inner side of the gas nozzle was within 3 mm.

[0058] (Evaluation 1: Average crystal grain size) For Example 4, the average crystal grain size of the inner wall surface of the through-hole was measured from the gas nozzle outlet (end face part) toward the inner side of the gas nozzle. The measurement points were measured every 0.5 mm with the gas nozzle outlet as zero. For the first region A, the values measured at two points of 0 mm and 0.5 mm were averaged, and for the second region B, the values measured at three points of 1.0 mm, 1.5 mm, and 2 mm were averaged. For the measurement, a non-contact scanning electron microscope (SEM) was used to obtain an image of the inner wall surface, and the number of particles and the average crystal grain size were obtained by image analysis.

[0059] (Evaluation 2: Particle generation amount) For Example 4, the chamber of a known ICP etching apparatus was used, and a corrosion test was performed for 12 hours with CF4 plasma. Then, the generation amount of particles was measured with a known airborne particle counter.

[0060] In the above Evaluation 1, for Example 4, the average crystal grain size in the first region A was 3.8 μm, the average crystal grain size in the second region B was 4.18 μm, and the ratio of the average crystal grain size in the second region B to the first region A was 1.1.

[0061] Also, in Evaluation 2, the particle generation amount was 1700 pts. The results of Example 4 are inferior to those of Example 1. However, compared with Comparative Example 1 and also with Examples 2 and 3, the amount of particle generation is sufficiently low, and it can be said that the effect of the present invention is still obtained.

Explanation of Reference Numerals

[0062] 1 Gas nozzle 1A End face (exit-side end face) 1B End face (entrance end face) 1C Side face 2 Through hole 2a Inner surface (inner wall) 2b Exit 2c Entrance A First region B Second region

Claims

【Claim 1】 A columnar gas nozzle made of a ceramic sintered body, having at least one through-hole through which gas flows, wherein both the entire inner surface of the through-hole and the end face provided with the outlet of the through-hole are fired surfaces, and the inner surface of the through-hole has a first region A near the outlet and a second region B located further inside than the first region A, the distance from the end face of the outlet to the inside in the first region A is within 0.5 mm, and the distance from the end face of the outlet in the second region B is within 3 mm further inside than the first region A, the average crystal grain size in the first region A is smaller than the average crystal grain size in the second region B, and the average crystal grain size in the second region B is 1.2 times or less that in the first region A. A gas nozzle characterized by this.

Images