Yttrium oxide material and method for manufacturing yttrium oxide material

Abstract

To provide an yttrium oxide material that is excellent in both arcing prevention and corrosion resistance, and a method for producing the same.SOLUTION: A yttrium oxide material according to the present invention is used for a semiconductor fabrication apparatus and comprises: 5 wt.% or more and 10 wt.% or less of oxygen; 60 wt.% or more and 70 wt.% or less of yttrium; 20 wt.% or more and 35 wt.% or less of a halogen element; and the balance comprising unavoidable impurities. The oxide material has: a density of at least 4.8 g / cm3; and the volume resistivity of 1×1012 Ω or more and 1×1015 Ω or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to yttrium oxide materials and methods for producing yttrium oxide materials, and more particularly to yttrium oxide materials suitable for use as components in semiconductor manufacturing equipment, and methods for producing such yttrium oxide materials. [Background technology]

[0002] It has been known for some time that abnormal discharge phenomena (arking) occur in ceramic components used in devices that generate high-density plasma. For example, electrostatic chucks made of ceramics are used in equipment for dry etching semiconductor wafers. However, abnormal discharge (arking) can occur in these electrostatic chucks, and when this occurs, particles are generated from the electrostatic chuck, and a decrease in yield occurs in the processing of semiconductor wafers.

[0003] To solve this problem, Patent Document 1 describes an electrostatic chuck that can prevent arcing that occurs when plasma density is increased. Specifically, Patent Document 1 describes an electrostatic chuck used in a semiconductor manufacturing apparatus comprising a cooling device and an electrostatic chuck body disposed on the cooling device and having a workpiece mounting surface, wherein (a) a gas supply hole extending through the cooling device from one main surface to the other main surface of the cooling device, and a main counterbore larger in diameter than the gas supply hole is provided at the opening of the gas supply hole, (b) an arcing prevention member made of an insulating material with a gas flow path in the center that communicates with the gas supply hole is embedded in the main counterbore, and (c) a small hole that communicates with the gas supply hole via the gas flow path is provided on the workpiece mounting surface.

[0004] Furthermore, Patent Document 1 indicates aluminum nitride-based ceramics, composite materials containing aluminum nitride, alumina-based ceramics, composite materials containing alumina, and composite ceramics of alumina and aluminum nitride as materials for the electrostatic chuck body. In addition, heat-resistant fluororesins such as polytetrafluoroethylene (e.g., Teflon®) and high-melting-point insulating ceramics such as alumina are indicated as materials for the arcing prevention member.

[0005] Thus, in the electrostatic chuck described in Patent Document 1, aluminum nitride-based ceramics or the like are used as the material for the electrostatic chuck body, and an arcing prevention member made of a heat-resistant fluororesin such as polytetrafluoroethylene (e.g., Teflon®) or a high-melting-point insulating ceramic such as alumina is embedded in the electrostatic chuck to protect areas where arcing is likely to occur.

[0006] Furthermore, Patent Document 2 lists YOF and / or Y5O4F7 as a constituent material for semiconductor manufacturing equipment such as etching equipment, which exhibits excellent resistance to halogen-based plasmas, and has a relative density of 70% or more in the sintered body, an open porosity of 10% or less, and a linear thermal expansion coefficient of 2.0 × 10⁻⁶ at 200-400°C. -6 / K or higher, 8.0×10 -6 A yttrium oxyfluoride sintered body is presented, characterized by having a temperature of 0.50 / K or less and a three-point bending strength of 10 MPa or more and 300 MPa or less.

[0007] Furthermore, Patent Document 3 describes a suitable coating for use in electrostatic chucks within plasma etching apparatus, exhibiting low temperature dependence of volume resistivity and low particle generation compared to halogen-based gas plasmas, resulting in a dense coating. Specifically, Patent Document 3 describes a multilayer coating comprising a lower layer made of a thermal spray coating containing an oxide of a rare earth element and a surface layer made of a thermal spray coating containing a fluoride and / or oxyfluoride of a rare earth element, with a volume resistivity of 1 × 10⁻¹⁶ at 23°C. 9 ~1 × 10 12A sprayed coating is shown that has a volume resistivity of Ω·cm and a temperature variable of the volume resistivity obtained by dividing the volume resistivity at 200°C by the volume resistivity at 23°C, which is 0.1 to 10.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] By the way, the method of protecting the location where arcing occurs as described in Patent Document 1 with an arcing prevention member made of an insulating member has the problem that the process becomes complicated in the production of ceramics. Further, there is also a risk that the arcing prevention member may be damaged during plasma processing, and if a gap occurs due to this damage, the countermeasure against arcing becomes insufficient.

[0010] Therefore, the inventors intensively studied to suppress the abnormal discharge phenomenon (arcing) and the generation of particles and the reduction in yield by improving the material of the electrostatic chuck body etc. without providing an arcing prevention member. Further, in this research, yttrium oxide (yttria), which has strong plasma resistance, was considered as the material of the electrostatic chuck body etc.

[0011] This yttria has a volume resistance Rate of about 1×10 16 Ω ·cm and is a high - resistance material. Therefore, when charges locally concentrate on a member using yttria, arcing is likely to occur. In particular, as dry etching equipment becomes more energy-intensive, applying high-frequency currents to dry etching equipment increases the probability of more arcing occurring in electrostatic chucks using yttria.

[0012] However, according to our research, when the yttrium oxide material has a specific range of content of yttrium, oxygen, and halogen elements, the density is 4.8 g / cm³. 3 That concludes the volume resistance. Rate is 1 x 10 12 Ω ·cm The above 1 x 10 15 Ω ·cm The following applies. Furthermore, we discovered that yttrium oxide materials possessing these properties can effectively suppress arcing without requiring a protective film such as an arcing prevention component, while also exhibiting excellent corrosion resistance, and thus completed the present invention.

[0013] Incidentally, Patent Document 2 describes the volume resistivity of a yttrium oxyfluoride sintered body. Rate There is no mention of this, and there is no volume resistor to prevent arcing. Rate The scope of this process is also not specified. Furthermore, if calcined bodies are obtained using yttrium oxyfluoride powder, new challenges may arise, such as high manufacturing costs and complex manufacturing conditions. Furthermore, Patent Document 3 describes the volume resistivity of a thermal spray coating containing rare earth element oxyfluoride. Rate It is described that arcing can be prevented, and the volume resistance of the sintered body. Rate The scope of this is not specified.

[0014] The present invention has been made in view of the above, and aims to provide a yttrium oxide material for use in semiconductor manufacturing equipment that is excellent in both arcing prevention effect and corrosion resistance, and a method for producing the yttrium oxide material. [Means for solving the problem]

[0015] The yttrium oxide material according to the present invention made to achieve the above object is a yttrium oxide material made of a fired body used in a semiconductor manufacturing apparatus, wherein oxygen is 5 wt% or more and 10 wt% or less, yttrium is 60 wt% or more and 70 wt% or less, a halogen element is 20 wt% or more and 35 wt% or less, the balance consists of inevitable impurities, and the density is at least 4.8 g / cm 3 and the volume resistivity is 1× 10 13 Ω·cm or more and 1×10 15 Ω·cm or less.

[0016] The yttrium oxide material according to the present invention is excellent in both the effect of preventing arcing and corrosion resistance, and is a suitable material as a material used for members of a semiconductor manufacturing apparatus.

[0017] Further, the method for producing a yttrium oxide material according to the present invention made to achieve the above object includes a step of firing a molded body prepared by mixing yttrium oxide and yttrium fluoride at a temperature of 800°C or more and 950°C or less in a reducing atmosphere. The existence of イットリウムオキシフッchemical compound しない It is characterized by including the step of firing a molded body prepared by mixing yttrium oxide and yttrium fluoride at a temperature of 800°C or more and 950°C or less in a reducing atmosphere.

[0018] Thus, by firing in a reducing atmosphere, oxygen defects, which are a kind of structural defect, can be increased, and the volume resistance Rate can be reduced, and a yttrium oxide material having a predetermined volume resistance Rate can be obtained.

Effects of the Invention

[0019] According to the present invention, it is possible to obtain a yttrium oxide material and a method for producing the yttrium oxide material that are excellent in both the effect of preventing arcing and corrosion resistance and are suitably used in a semiconductor manufacturing apparatus.

Modes for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described in detail. The yttrium oxide material according to the present invention is a calcined body comprising 5% to 10% by weight of oxygen, 60% to 70% by weight of yttrium, 20% to 35% by weight of halogen elements, and the remainder being unavoidable impurities, with a density of at least 4.8 g / cm³. 3 and volume resistance Rate is 1 x 10 12 Ω ·cm The above 1 x 10 15 Ω ·cm The following is a suitable material for use in semiconductor manufacturing equipment.

[0021] The yttrium oxide material according to the present invention, being a yttrium oxide, exhibits strong plasma resistance, excellent corrosion resistance, and also has high volume resistivity. Rate Because it is smaller than conventional designs, it avoids localized charge concentration and prevents arcing. Furthermore, as described above, the yttrium oxide material according to the present invention contains 5% to 10% by weight of oxygen, 60% to 70% by weight of yttrium, and 20% to 35% by weight of halogen elements, with the remainder being unavoidable impurities. In other words, the yttrium oxide material according to the present invention consists of three or more elements, including oxygen and yttrium, which are the main components of yttrium oxide (yttrium oxide), plus a halogen element. Furthermore, two or more halogen elements may be applied to form a compound of four or more elements.

[0022] In this invention, the product contains so-called unavoidable impurities, such as impurities derived from each raw material and impurities introduced during the manufacturing process. These unavoidable impurities are present in trace amounts and are considered to have little effect on the efficacy of the present invention.

[0023] Furthermore, as mentioned above, the reason for specifying that oxygen should be between 5% and 10% by weight, and yttrium between 60% and 70% by weight is that if the values ​​fall outside these ranges, the same level of plasma resistance (degree of plasma erosion) as that observed with stoichiometric ratio yttrium oxide cannot be expected, making it difficult to use in dry etching equipment and the like.

[0024] Furthermore, the proportion of halogen elements is between 20% and 35% by weight of yttrium oxide. When halogen elements are less than 20% by weight, the volume resistivity of yttrium oxide is low. Rate is 1 x 10 15 Ω ·cm This exceeds the limit, resulting in little effect on arcing. On the other hand, if the halogen element exceeds 35% by weight of the yttrium oxide, the ratio of oxygen to yttrium will not fall within the range of 5% to 10% by weight for oxygen and 60% to 70% by weight for yttrium. This can lead to a deterioration in plasma resistance, potentially making the material unsuitable for use in semiconductor manufacturing equipment.

[0025] The density of the yttrium oxide material according to the present invention is at least 4.8 g / cm³. 3 That is the case. Density is 4.8 g / cm³ 3 Below a certain level, the presence of many pores in yttrium oxide leads to reduced plasma resistance and volume resistivity. Rate This leads to an increase in [value], which is undesirable. Here, a higher density is preferable, and may be equivalent to the theoretical density of yttrium oxide.

[0026] The yttrium oxide material according to the present invention has an oxygen content of 5% to 10% by weight, a yttrium content of 60% to 70% by weight, and a halogen element content of 20% to 35% by weight. If any of these content falls outside this range, pores will not be sufficiently reduced during firing, and the density will be 4.8 g / cm³. 3 There are concerns that it will fall below that level.

[0027] The aforementioned density adjustment can also be achieved by appropriately changing conditions that reduce pores, such as the firing temperature and firing time. Furthermore, the method for measuring density in this invention is not particularly limited, but preferably, methods such as the boiling method and the vacuum method specified in JIS R1634 can be applied.

[0028] Volume resistivity of the yttrium oxide material according to the present invention Rate is 1 × 10 12 Ω ·cm The above 1 x 10 15 Ω ·cm The following applies: This volume resistance Rate is 1 x 10 12 Ω ·cm Below this value, the electrical conductivity in the yttrium oxide is high, making it difficult to control plasma generation in the dry etching apparatus, which is undesirable. On the other hand, volume resistivity Rate is 1 x 10 15 Ω ·cm If the value exceeds this, the arcing prevention effect will not be sufficiently obtained, which is undesirable. Furthermore, the anti-arking effect is 1 x 10 13 Ω ·cm The above 1 x 10 15 Ω ·cm It can be sufficiently obtained within the following range. Furthermore, a higher volume resistivity can suppress plasma generation more effectively. Therefore, this volume resistivity Rate is 1 × 10 13 Ω ·cm The above 1 x 10 15 Ω ·cm The following is more preferable:

[0029] Furthermore, in this invention, volume resistance Rate While this does not limit the measurement method, the volume resistivity measurement method specified in JIS C2139 can be applied.

[0030] This yttrium oxide has a volume resistivity. Rate For example, this value can be reduced by adding a halogen element that has a monovalent anion. The halogen elements referred to here include fluorine, chlorine, bromine, and iodine, but fluorine is particularly preferred due to its ease of handling.

[0031] Furthermore, the volume resistance of ceramics Rate This is also related to the structural defects present within it; for example, firing ceramics in a reducing atmosphere increases oxygen vacancies, which are a type of structural defect, thus increasing volume resistance. Rate You can make it smaller. Specifically, by firing a molded body made by mixing yttrium oxide and yttrium fluoride in a reducing atmosphere, the oxygen vacancies, a type of structural defect, are increased, thereby improving the volume resistivity of the yttrium oxide. Rate You can make it smaller.

[0032] The method for producing yttrium oxide material according to the present invention is characterized by including a step of firing a molded body made by mixing yttrium oxide and yttrium fluoride in a reducing atmosphere at a temperature of 800°C to 950°C, as described above.

[0033] Here, the reducing atmosphere is one of the following: vacuum, hydrogen atmosphere, nitrogen atmosphere, argon atmosphere, or a combination of these. Rate Considering the trade-off with the reduction effect, an (argon) atmosphere is more preferable.

[0034] Furthermore, in the method for producing yttrium oxide material according to the present invention, the firing temperature is in the range of 800°C to 950°C. If the firing temperature is below 800°C, yttrium oxide cannot be sintered to a sufficient density, and if it exceeds 950°C, the volume resistivity is affected. Rate This is undesirable because it makes it difficult to include it within the scope of the present invention.

[0035] In the method for producing yttrium oxide material according to the present invention, yttrium oxyfluoride is not present before firing. During firing, fluorine produced by the decomposition of yttrium fluoride reacts with yttrium oxide, and a portion of it is produced as yttrium oxyfluoride.

[0036] Therefore, when comparing the sintered body described in Patent Document 2, which is obtained by calcining a yttrium oxyfluoride raw material, with the yttrium oxide material according to the present invention, the proportion of yttrium oxyfluoride in the present invention is considerably smaller. As a result, the yttrium oxide material according to the present invention possesses, to some extent, the excellent corrosion resistance of yttrium oxyfluoride, while also exhibiting high volume resistance. Rate This material achieves two desirable characteristics simultaneously: a reduction in [specific characteristic] and a reduction in [specific characteristic], resulting in an unprecedentedly superior material.

[0037] Thus, by adding halogen elements to rare earth element oxides in a predetermined ratio, and carrying out the firing under predetermined atmospheric and firing temperatures, the volume resistivity is increased. Rate Adjustments can be made. As a result, it is possible to obtain a yttrium oxide material that has arcing prevention effects while ensuring plasma resistance. [Examples]

[0038] The present invention will be described in detail below based on examples, but the present invention is not limited to the examples shown below.

[0039] (Example 1) Yttrium oxide powder (99.9% purity) and yttrium fluoride powder (99.9% purity) were weighed out to achieve the following concentrations: 7.5% by weight of oxygen, 64% by weight of yttrium, and 28.5% by weight of fluorine. Next, polyvinyl alcohol was weighed as a binder to make up 1% by weight of the total powder weight. Furthermore, pure water was weighed so that the weight ratio of the total powder in pure water was 65%. After mixing all of these together, the mixture was granulated using a spray drying device, and the recovered granulated powder was formed into a (plate-like) shape using a dry press. The obtained molded body was heated to 600°C in air to remove the polyvinyl alcohol, and then fired in an argon atmosphere at 900°C for 60 minutes to obtain a fired body for evaluation.

[0040] The density of the calcined body obtained in Example 1 was measured to be 5.05 g / cm³. 3 It was. Also, volume resistance Rate When measured, it was found to be 1 × 10 13 Ω ·cmHere, density was measured in accordance with (JIS R1634), and volume resistance was... Rate The measurement was performed according to JIS C2139.

[0041] (Example 2) The procedure was the same as in Example 1, except that yttrium oxide powder and yttrium fluoride powder were weighed to obtain a composition of 5.5% by weight of oxygen, 62% by weight of yttrium, and 32.5% by weight of fluorine. The density of the resulting calcined body was 5.02 g / cm³. 3 Therefore, volume resistance Rate is 5 x 10 12 Ω ·cm That was the case.

[0042] (Example 3) The procedure was the same as in Example 1, except that yttrium oxide powder and yttrium fluoride powder were weighed to obtain a composition of 9.8% by weight of oxygen, 68% by weight of yttrium, and 22.2% by weight of fluorine. The density of the resulting calcined body was 5.05 g / cm³. 3 Therefore, volume resistance Rate is 2 × 10 14 Ω ·cm That was the case.

[0043] (Example 4) The procedure was the same as in Example 1, except that yttrium oxide powder and yttrium fluoride powder were weighed to obtain a composition of 6.0% by weight of oxygen, 65% by weight of yttrium, and 29% by weight of fluorine. The density of the resulting calcined body was 5.03 g / cm³. 3 Therefore, volume resistance Rate is 4 x 10 13 Ω ·cm That was the case.

[0044] (Comparative Example 1) The procedure was the same as in Example 1, except that yttrium oxide powder and yttrium fluoride powder were weighed to obtain a composition of 6.5% by weight of oxygen, 75% by weight of yttrium, and 18.5% by weight of fluorine. The density of the resulting calcined body was 4.76 g / cm³. 3 Therefore, volume resistance Rate is 2 × 10 15 Ω ·cm That was the case.

[0045] (Comparative Example 2) The procedure was the same as in Example 1, except that yttrium oxide powder and yttrium fluoride powder were weighed to achieve a composition of 12% by weight of oxygen, 72% by weight of yttrium, and 23% by weight of fluorine. The density of the resulting calcined body was 4.75 g / cm³. 3 Therefore, volume resistance Rate is 4 x 10 15 Ω ·cm That was the case.

[0046] (Comparative Example 3) The procedure was the same as in Example 1, except that yttrium oxide powder and yttrium fluoride powder were weighed to obtain a composition of 4.5% by weight of oxygen, 57% by weight of yttrium, and 38.5% by weight of fluorine. The density of the resulting calcined body was 4.78 g / cm³. 3 Therefore, volume resistance Rate is 4 x 10 11 Ω ·cm That was the case.

[0047] (Comparative Example 4) The conditions were the same as in Example 1, except that the firing time was halved. The density of the resulting fired body was 4.72 g / cm³ 3 Therefore, volume resistance Rate is 3 x 10 11 Ω ·cm That was the case.

[0048] (Comparative Example 5) Yttrium oxide powder and yttrium fluoride powder were weighed to achieve a composition of 7.5% by weight of oxygen, 64% by weight of yttrium, and 28.5% by weight of fluorine. The procedure was the same as in Example 1, except that the firing temperature was set to 750°C. The density of the resulting fired body was 4.70 g / cm³. 3 Therefore, volume resistance Rate is 2 × 10 15 Ω ·cm That was the case.

[0049] (Comparative Example 6) Yttrium oxide powder and yttrium fluoride powder were weighed to achieve a composition of 7.5% by weight of oxygen, 64% by weight of yttrium, and 28.5% by weight of fluorine. The procedure was the same as in Example 1, except that the calcination temperature was set to 980°C. The density of the resulting calcined body was 4.78 g / cm³. 3 Therefore, volume resistance Rate is 3 x 10 15 Ω ·cm That was the case.

[0050] (Comparative Example 7) Yttrium oxide powder and yttrium fluoride powder were weighed to achieve a composition of 7.5% by weight of oxygen, 64% by weight of yttrium, and 28.5% by weight of fluorine. The procedure was the same as in Example 1, except that the firing atmosphere was air. The density of the resulting fired body was 4.70 g / cm³. 3 Therefore, volume resistance Rate is 3 x 10 15 Ω ·cm That was the case.

[0051] Furthermore, each sample from Examples 1-4 and Comparative Examples 1-7 was placed inside a plasma generator, and while maintaining a vacuum of 0.05 Torr, a voltage of 850V was applied between the samples for 5 minutes. After the application, the samples were removed, and traces of arcing were confirmed using an optical microscope or scanning electron microscope. The results are shown in Table 1.

[0052] [Table 1]

[0053] As shown in Examples 1 to 4 above, if the weight ratio of oxygen, yttrium, and fluorine is within the range of the present invention, then density and volume resistivity Rate This also falls within the scope of the present invention. These densities and volume resistivity Rate If this falls within the scope of the present invention, the corrosion resistance of yttrium oxide and the volume resistance improved by fluorine addition are considered. Rate It was found to possess both the anti-arking effect obtained from the other method and the anti-arking effect obtained from the other method.

[0054] In Comparative Example 1, the amount of yttrium was above the preferred range, so it was not sufficiently densified, and the density was 4.8 g / cm³. 3 It fell below that. And because the density fell below the range of the present invention, the volume resistance Rate It is presumed that this increased.

[0055] In Comparative Example 2, the oxygen content was higher than the preferred range, resulting in insufficient densification and a density of 4.8 g / cm³. 3 It fell below that. And because the density fell below the range of the present invention, the volume resistance Rate It is presumed that this increased.

[0056] In Comparative Example 3, the fluorine content was higher than the preferred range, so densification was not sufficient, resulting in a density of 4.8 g / cm³. 3 It fell below that level. Also, because fluorine is present in excessive amounts beyond the scope of the present invention, the conductivity increases and the volume resistance increases. Rate It is presumed that this falls below the scope of the present invention.

[0057] Comparative Example 4, although containing oxygen, yttrium, and fluorine within the scope of the present invention, did not undergo sufficient firing, resulting in a considerable amount of pores remaining and preventing densification.

[0058] In Comparative Example 5, the firing temperature was lowered to 750°C, resulting in insufficient densification and a density of 4.8 g / cm³. 3 It fell below that. And because the density fell below the range of the present invention, the volume resistance Rate It is presumed that this increased.

[0059] In Comparative Example 6, the firing temperature was set high at 980°C, resulting in insufficient densification and a density of 4.8 g / cm³. 3 It fell below that. And because the density fell below the range of the present invention, the volume resistance Rate It is presumed that this increased.

[0060] In Comparative Example 7, the firing atmosphere was set to atmospheric pressure, resulting in insufficient densification and a density of 4.8 g / cm³. 3 It fell below that. And because the density fell below the range of the present invention, the volume resistance Rate It is presumed that this increased.

[0061] Thus, in Comparative Examples 1 to 7, the density and volume resistivity are outside the scope of the present invention, and therefore, corrosion resistance and volume resistivity Rate It was found that it does not possess both of the anti-arking effects obtained from the other method.

Claims

1. A yttrium oxide material consisting of a calcined body, used in semiconductor manufacturing equipment, It consists of 5% to 10% by weight of oxygen, 60% to 70% by weight of yttrium, 20% to 35% by weight of halogen elements, and the remainder being unavoidable impurities. Density of at least 4.8 g / cm³ ３ Furthermore, the volume resistivity is 1 × 10¹³ Ω·cm or more. １５ A yttrium oxide material characterized by having a density of Ω·cm or less.

2. A method for producing a yttrium oxide material according to claim 1, A method for producing a yttrium oxide material, characterized by including a step of firing a molded body, which is prepared by mixing yttrium oxide and yttrium fluoride and is free of yttrium oxyfluoride, at a temperature of 800°C to 950°C in a reducing atmosphere.

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