Yttrium oxide sintered body and components for semiconductor manufacturing equipment

Abstract

To provide an yttrium oxide sintered body capable of increasing resistance to corrosive chemicals while maintaining high resistance to plasma and corrosive chemicals, and to provide a component for a semiconductor manufacturing apparatus.SOLUTION: An yttrium oxide sintered body is composed mainly of yttrium oxide and contains 0.1 to 5.0 wt% of zirconium in terms of ZrO2. By adding a certain amount of zirconium oxide to yttrium oxide, there can be obtained yttrium oxide sintered body having improve resistance to corrosive chemicals while maintaining excellent resistance to plasma and corrosive gases.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a yttrium oxide sintered body and a member for a semiconductor manufacturing apparatus using the same.

Background Art

[0002] Conventionally, as a member for a semiconductor manufacturing apparatus, particularly a member used in a plasma environment, a yttrium oxide (Y2O3) sintered body having excellent plasma resistance has been used. Since a member for a semiconductor manufacturing apparatus needs to prevent contamination of a workpiece by impurities (such as particles), a high-purity yttrium oxide sintered body is used as such a member.

[0003] Patent Document 1 discloses that when a small amount of a metal component is contained in yttria ceramics, the small amount of the metal component tends to segregate at the grain boundaries of yttria crystals. When a yttria ceramic component containing such a small amount of the metal component is exposed to a plasma atmosphere, the metal component is more likely to be corroded than yttria crystals in the plasma atmosphere. Therefore, corrosion starts from the grain boundaries, and when the grain boundaries of yttria crystals near the surface are corroded, the yttria crystals fall off and adhere to the silicon wafer as dust. In response to this problem, yttria ceramic components having a purity of 99.9 wt% or more and a high purity, and a content of trace metal components of Si: 100 ppm or less and Ca: 20 ppm or less on a mass basis are disclosed.

[0004] Patent Document 2 discloses a corrosion-resistant ceramic material mainly composed of an oxide containing at least one element belonging to Group 3A of the periodic table and at least one element belonging to Group 4A of the periodic table. Y, La, and Yb are exemplified as Group 3A, and Ti and Zr are exemplified as Group 4A. It is described that the amount of the element belonging to Group 4A is 0.03 to 70 wt% in terms of oxide in the whole.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-021990 [Patent Document 2] Japanese Patent Publication No. 2000-001362 [Overview of the project] [Problems that the invention aims to solve]

[0006] While yttrium oxide sintered bodies exhibit excellent resistance to plasma gases, they do not have high resistance to acidic chemicals such as nitric acid or hydrochloric acid. However, the high-purity yttrium oxide sintered body described in Patent Document 1 focuses on improving plasma resistance but does not consider chemical resistance.

[0007] Furthermore, in Patent Document 2, the content of group 4A elements in the corrosion-resistant ceramic material varies greatly, from 0.03 to 70 wt%. However, when the content of group 4A elements increases, segregation of group 4A elements is more likely to occur in the sintered body, reducing the corrosion resistance of the segregated areas and making those areas more easily selectively etched. Also, while Patent Document 2 focuses on increasing the plasma resistance of ceramic materials, it does not consider chemical resistance.

[0008] This invention has been made in view of these circumstances, and aims to provide a yttrium oxide sintered body and a component for semiconductor manufacturing equipment that can maintain excellent resistance to plasma and corrosive gases while also having high resistance to corrosive chemicals. [Means for solving the problem]

[0009] (1) To achieve the above objective, the yttrium oxide sintered body of the present invention is a yttrium oxide sintered body characterized by having yttrium oxide as the main component and containing 0.1 wt% to 5.0 wt% of zirconium in terms of ZrO2.

[0010] Thus, by creating a yttrium oxide sintered body containing a certain amount of zirconium oxide in addition to yttrium oxide, it is possible to maintain excellent resistance to plasma and corrosive gases while also increasing resistance to corrosive chemicals.

[0011] (2) Furthermore, the yttrium oxide sintered body of the present invention is characterized by containing 0.5 wt% to 1.0 wt% of zirconium in terms of ZrO2.

[0012] In this way, by adjusting the amount of zirconium oxide contained in the yttrium oxide sintered body, it is possible to improve the balance between resistance to plasma and corrosive gases and resistance to corrosive chemicals.

[0013] (3) Furthermore, the yttrium oxide sintered body of the present invention is characterized in that the total content of metal elements other than yttrium and zirconium is 1000 ppm or less, and the content of Si, Ca, and Na among the metal elements is 150 ppm or less each.

[0014] In this way, by creating a yttrium oxide sintered body that contains as few metals other than yttrium and zirconium as possible, its corrosion resistance can be made comparable to that of a high-purity (99.9% or higher) yttrium oxide sintered body.

[0015] (4) Furthermore, the semiconductor manufacturing apparatus component of the present invention is characterized by being made of a yttrium oxide sintered body as described in any of (1) to (3) above.

[0016] This makes it possible to create semiconductor manufacturing equipment components that offer both resistance to plasma and corrosive gases, as well as resistance to corrosive chemicals. [Effects of the Invention]

[0017] According to the present invention, it is possible to achieve high resistance to corrosive chemicals while maintaining excellent resistance to plasma and corrosive gases.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic cross-sectional view showing an example of the use of a member for a semiconductor manufacturing apparatus according to an embodiment of the present invention. [Figure 2] It is a flowchart showing an example of the manufacturing process of a yttrium oxide-based sintered body according to an embodiment of the present invention. [Figure 3] It is a table showing various evaluation results of sintered bodies of Examples and Comparative Examples.

Embodiments of the Invention

[0019] Next, embodiments of the present invention will be described with reference to the drawings. For ease of understanding of the description, the same reference numerals are assigned to the same components in each drawing, and duplicate descriptions are omitted. In the configuration diagrams, the sizes of the respective components are conceptually represented and do not necessarily represent actual dimensional ratios.

[0020] [Configuration of Yttrium Oxide-Based Sintered Body] The yttrium oxide-based sintered body of the present invention contains zirconium in an amount of 0.1 wt% or more and 5.0 wt% or less in terms of ZrO2, with yttrium oxide (Y2O3) as the main component. Containing yttrium oxide as the main component means containing yttrium oxide in an amount of 94.5 wt% or more and less than 99.9 wt%. It is preferable that the total amount of the yttrium oxide-based sintered body in terms of Y2O3 and ZrO2 is 99.5 wt% or more, and more preferably 99.9 wt% or more.

[0021] By thus making the yttrium oxide-based sintered body contain a certain amount of zirconium oxide in yttrium oxide, it is possible to increase the resistance to corrosive chemicals while maintaining excellent resistance to plasma and corrosive gases.

[0022] If the zirconium oxide content is less than 0.1 wt%, the effect of improving chemical resistance will be small. Furthermore, if it exceeds 5.0 wt%, sinterability will deteriorate, increasing the risk of pore formation in the sintered body. Increased pores in the sintered body worsen plasma resistance. Additionally, segregation of zirconium oxide may occur, which impairs plasma resistance. For these reasons, the zirconium oxide content should be kept within the above range.

[0023] Furthermore, the zirconium oxide content is preferably 0.5 wt% or more. Also, the zirconium oxide content is preferably 1.0 wt% or less. By adjusting the amount of zirconium oxide contained in the yttrium oxide sintered body in this way, a good balance can be achieved between resistance to plasma and corrosive gases and resistance to corrosive chemicals.

[0024] In yttrium oxide sintered bodies, it is preferable that the entire amount of zirconium oxide is dissolved in the yttrium oxide. Because yttrium oxide has excellent resistance to plasma and corrosive gases, when the entire amount of zirconium oxide is dissolved in the yttrium oxide, the zirconium oxide crystals do not exist as crystals, but rather dissolve into the yttrium oxide crystals without changing the crystal structure of the yttrium oxide. This makes it possible to create a sintered body that has a good balance of resistance to chemicals and resistance to corrosive gases.

[0025] Furthermore, the fact that the entire amount of zirconium oxide is dissolved in yttrium oxide can be confirmed as follows. First, glow discharge mass spectrometry (GD-MS) is used to confirm that yttrium and zirconium are present in the cross-section of the yttrium oxide sintered body. Separately, the crystal structure of the same cross-section is examined by XRD to confirm that the crystalline phase of yttrium oxide is detected, while the crystalline phase of zirconium oxide and the crystalline phase of a composite oxide of yttrium oxide and zirconium oxide are not detected. This confirms that the entire amount of zirconium oxide is dissolved in yttrium oxide.

[0026] The yttrium oxide sintered body preferably has a total content of metallic elements other than yttrium and zirconium of 1000 ppm or less. By limiting the total content of metallic elements other than yttrium and zirconium to 1000 ppm or less, sufficient plasma resistance can be ensured. Examples of metallic elements other than yttrium and zirconium include Si, Ca, Na, Mg, Ti, Cr, Fe, Ni, Cu, and P. In this invention, metallic elements also include metalloid elements such as Si and P.

[0027] These trace metals tend to condense mainly in the grain boundary layer of the yttrium oxide sintered body, and corrosion in the plasma environment progresses more rapidly than that of yttrium oxide or zirconium oxide. If corrosion of the trace metal components progresses first, particle detachment occurs due to corrosion at the grain boundaries, worsening the plasma resistance. For this reason, it is preferable to keep the content of metal elements other than yttrium and zirconium as low as possible. Therefore, the content of metals other than yttrium and zirconium is preferably 500 ppm or less, and more preferably 300 ppm or less. In order to keep the content of trace metals within the above range, it is necessary to control the raw material powder and manufacturing process to prevent contamination by impurities.

[0028] In yttrium oxide sintered bodies, the content of Si, Ca, and Na among the metallic elements excluding yttrium and zirconium is preferably 150 ppm or less each. Since Si, Ca, and Na have a particularly large impact on plasma resistance, controlling the content of these elements is important. The content of Si, Ca, and Na is more preferably 100 ppm or less each, and even more preferably 50 ppm or less each.

[0029] In this way, by creating a yttrium oxide sintered body that contains as few metallic elements as possible other than yttrium and zirconium, its plasma resistance can be made comparable to that of a high-purity (99.9% or higher) yttrium oxide sintered body. The metallic element content in the yttrium oxide sintered body can be measured by glow discharge mass spectrometry (GD-MS).

[0030] Furthermore, the yttrium oxide sintered body preferably has a relative density of 90% or higher. Because the relative density is sufficiently high, it exhibits high plasma resistance, excellent strength as a sintered body, and is suitable for use as a large component.

[0031] The relative density of a yttrium oxide sintered body can be expressed as (sintered body density / theoretical density) × 100 (%). The theoretical density is the density of elemental yttrium oxide (5.01 g / cm³). 3 ) refers to the density of the sintered body, which is the density of the yttrium oxide sintered body measured by the Archimedes method.

[0032] [Configuration of components for semiconductor manufacturing equipment] Next, the semiconductor manufacturing apparatus components of the present invention will be described. Figure 1 is a schematic cross-sectional view showing an example of use of the semiconductor manufacturing apparatus components according to an embodiment of the present invention. The semiconductor manufacturing apparatus components of the present invention can be suitably used, for example, as a gas nozzle 10 or a container body 21 or lid member 22 that constitute a reaction vessel 20 used in a plasma apparatus 100 such as a film deposition apparatus for forming a thin film on a substrate W such as a semiconductor wafer or a glass substrate, or an etching apparatus for performing microfabrication on a substrate W in a semiconductor manufacturing process or a liquid crystal manufacturing process.

[0033] For example, in a film deposition apparatus, a raw material gas containing a corrosive gas is introduced into a reaction vessel 20 using a gas nozzle 10, and a thin film is formed on a substrate W by plasma CVD (Chemical Vapor Deposition) method, which involves plasmaizing this raw material gas. In an etching apparatus, a halogen-based corrosive gas is introduced into the reaction vessel 20 using a gas nozzle 10 as a raw material gas, and this corrosive gas is plasmaized to create an etching gas, thereby performing microfabrication on the substrate W.

[0034] The gas nozzle 10 has a gas supply port 11 through which a gas such as a corrosive gas is supplied from a gas supply unit (not shown), a gas outlet 12 for discharging the gas into the reaction vessel 20, and a nozzle hole 13 that connects the gas supply port 11 and the gas outlet 12.

[0035] The semiconductor manufacturing apparatus component according to an embodiment of the present invention is a component having a portion exposed to corrosive gas or corrosive chemicals, and in this case, it is a component that constitutes at least a part of the portion of the gas nozzle 10 that is exposed to corrosive gas, for example, the portion including the nozzle hole 13, and the portion exposed inside the reaction vessel 20. However, the semiconductor manufacturing apparatus component may constitute the entire gas nozzle 10. Furthermore, the corrosion-resistant component may be, for example, the container body 21 or the lid member 22 that constitute the reaction vessel 20, or a part thereof.

[0036] [Method for manufacturing yttrium oxide sintered bodies] Next, the method for manufacturing a yttrium oxide sintered body according to the present invention will be described. Figure 2 is a flowchart showing an example of the manufacturing process for a yttrium oxide sintered body according to an embodiment of the present invention.

[0037] First, yttrium oxide powder and zirconium oxide powder are prepared as raw material powders for the yttrium oxide sintered body. The purity of each powder is preferably 99.9% or higher, and more preferably 99.99% or higher. The average particle size of each powder is preferably between 0.1 μm and 10 μm. Next, each powder is weighed so that the zirconium content in the yttrium oxide sintered body after sintering is a predetermined value in the range of 0.1 wt% to 5.0 wt% in terms of ZrO2 (STEP 1).

[0038] Next, the raw material powders are mixed. Each powder is placed in a pot together with a binder (such as PVA), and the mixture is pulverized and mixed by wet mixing using a ball mill to create a raw material slurry (STEP 2). Ion-exchanged water or a dispersant may be used to prepare the raw material slurry. For example, a ball mill can be made with resin balls. The mixing time can be, for example, 20 hours.

[0039] Next, the slurry obtained in the mixing step is dried and granulated (STEP 3). One method for obtaining granulated powder from the slurry is to remove the solvent from the slurry by drying it in a water bath, and then pass the resulting powder through a sieve. Alternatively, a spray dryer can be used.

[0040] Next, the granulated powder obtained in the granulation process is molded to form a molded body (STEP 4). The molding method can include methods such as placing the obtained granulated powder into a mold and press molding. Press molding methods include known methods such as uniaxial press molding, cold isostatic pressing (CIP), and hot pressing. The molding pressure can be, for example, 98 MPa in the case of press molding.

[0041] Next, the molded body is fired (STEP 5). The firing process involves firing the molded body in an oxidizing atmosphere or a vacuum atmosphere at a temperature of 1600°C to 2000°C to obtain a yttrium oxide sintered body. The firing time is preferably 1 hour to 20 hours. A degreasing step may be added before the firing process if necessary. Furthermore, a step of densifying the yttrium oxide sintered body by pressurizing it using HIP may be included.

[0042] This process makes it possible to manufacture yttrium oxide sintered bodies that possess both resistance to plasma and corrosive gases and resistance to corrosive chemicals.

[0043] [Examples and Comparative Examples] (Example 1) Yttrium oxide raw material powder (purity 99.9%, average particle size 1 μm) and zirconium oxide (ZrO2) raw material powder (purity 99.99%, average particle size 0.1 μm) were weighed so that 0.1 wt% of ZrO2 was contained in the yttrium oxide sintered body. Next, 2.0 mass% of a PVA-based binder as a binder, 0.3 mass% of a water-soluble acrylic dispersant as a dispersant as a dispersant, and an appropriate amount of deionized water were added to the weighed raw material powders in a pot, and a raw material slurry was formed by wet mixing using a ball mill. Next, this raw material slurry was dried and granulated using a spray dryer. Next, the granulated powder was put into a mold and a molded body was produced by cold isostatic pressing (CIP). Next, the obtained molded body was fired at a temperature of 1700°C in an air atmosphere for 10 hours to obtain the yttrium oxide sintered body of Example 1.

[0044] (Example 2) The yttrium oxide sintered body of Example 2 was produced under the same conditions as in Example 1, except that the amount of ZrO2 contained in the sintered body was weighed to be 0.2 wt%.

[0045] (Example 3) The yttrium oxide sintered body of Example 3 was produced under the same conditions as in Example 1, except that the amount of ZrO2 contained in the sintered body was weighed to be 0.5 wt%.

[0046] (Example 4) The yttrium oxide sintered body of Example 4 was produced under the same conditions as in Example 1, except that the amount of ZrO2 contained in the sintered body was weighed to be 1.0 wt%.

[0047] (Example 5) The yttrium oxide sintered body of Example 5 was produced under the same conditions as in Example 1, except that the amount of ZrO2 contained in the sintered body was weighed to be 5.0 wt%.

[0048] (Comparative Example 1) A sintered body of Comparative Example 1, containing only yttrium oxide, was produced under the same conditions as in Example 1, except that zirconium oxide was not added.

[0049] (Comparative Example 2) A sintered body of Comparative Example 2 containing yttrium oxide and ZrO2 was manufactured under the same conditions as in Example 1, except that the amount of ZrO2 contained in the sintered body was weighed to be 8.0% by mass.

[0050] (Evaluation method) Multiple test specimens were cut from the sintered bodies of the examples and comparative examples, and the following measurements were performed.

[0051] (1) Plasma resistance test For both the examples and comparative examples, test specimens were prepared, one side was mirror-polished, and a portion of it was masked with polyimide tape. The test specimens were then placed in a plasma etching apparatus. The RIE etching apparatus was set to use NF3 as the etching gas, a plasma irradiation time of 4 hours, and a high-frequency output of 2000W. The corrosion depth before and after plasma treatment was confirmed. Specimens with a corrosion depth of 0.7 μm or less were marked as particularly excellent (◎), and those with a corrosion depth between 0.7 μm and 0.8 μm were marked as good (○), both considered passing grades. Specimens with a corrosion depth greater than these were marked as poor (×) and considered failing grades.

[0052] (2) Chemical resistance test Test specimens were prepared for both the examples and comparative examples. The specimens were placed in a container containing hydrohalic acid, and after a predetermined immersion time, the surface condition was checked by SEM (1000x magnification) observation to see if microscopic scratches caused by polishing had opened and appeared on the surface. First, the same batch of specimens were polished and ground, then placed in a container containing the prepared hydrohalic acid and immersed in the chemical. Next, surface SEM observation was performed after 6 hours, and specimens in which scratches were observed at this point were evaluated as poor and failed. Then, specimens in which no scratches were observed were immersed in the chemical again, and surface SEM observation was performed after 18 hours (24 hours in total). At this point, specimens in which scratches were observed were evaluated as excellent, and specimens in which no scratches were observed were evaluated as particularly excellent, and both were evaluated as passing.

[0053] In other words, the evaluation criteria were as follows: items that showed no damage after 24 hours of immersion in hydrohalic acid were marked with ◎ as particularly excellent, items that showed damage between 6 hours and 24 hours were marked with ○ as excellent, and items that showed damage in 6 hours or less were marked with × as poor and failed.

[0054] (3) Confirmation of the content of zirconium oxide and metal impurities in the sintered body The zirconium oxide and other metallic element content in the sintered bodies of each test specimen was confirmed by glow discharge mass spectrometry (GD-MS).

[0055] (Evaluation results) The table in Figure 3 shows the evaluation results for various aspects of the sintered bodies of the examples and comparative examples. As shown in the table in Figure 3, Examples 1 to 5, which are yttrium oxide sintered bodies of the present invention, received an evaluation of ○ or higher for plasma resistance and chemical resistance.

[0056] Among the examples, Examples 3 and 4 showed particularly excellent plasma resistance and chemical resistance. Therefore, it was found that the zirconium oxide contained in the yttrium oxide sintered body is preferably 0.5 wt% to 1.0 wt% in terms of ZrO2.

[0057] On the other hand, as shown in the table in Figure 3, Comparative Example 1, which did not contain zirconium oxide, showed good plasma resistance but poor chemical resistance. Similarly, Comparative Example 2, whose zirconium oxide content exceeded the range of the present invention, showed good chemical resistance but poor plasma resistance. Comparative Example 2 was found to have numerous pores and microscopic cracks in the sintered body. This is thought to be the reason for the deterioration of plasma resistance. As a result, it was found that the zirconium content of the yttrium oxide sintered body is preferably 5.0 wt% or less in terms of ZrO2.

[0058] In the yttrium oxide sintered body of the example, X-ray diffraction (XRD) confirmed that only the yttrium oxide crystalline phase was present; neither the zirconium oxide crystalline phase nor the composite oxide crystalline phase of yttrium oxide and zirconium oxide was detected. Furthermore, high-power XRD measurements also failed to detect either the zirconium oxide crystalline phase or the composite oxide crystalline phase of yttrium oxide and zirconium oxide. In other words, it can be said that the entire amount of added zirconium oxide in the yttrium oxide sintered body of the example is dissolved in the yttrium oxide. This is considered to be the reason why the yttrium oxide sintered body of the present invention exhibits high plasma resistance and chemical resistance.

[0059] The results above confirm that the yttrium oxide sintered body of the present invention has sufficiently high plasma resistance and chemical resistance. Furthermore, it was confirmed that, due to its high plasma resistance and chemical resistance, the semiconductor manufacturing equipment component can be suitably used as a component in parts that may be exposed to both plasma and chemicals.

[0060] The present invention is not limited to the embodiments described above, and it goes without saying that it extends to various modifications and equivalents that fall within the spirit and scope of the present invention. Furthermore, the structure, shape, number, position, size, etc., of the components shown in each drawing are for illustrative purposes only and may be modified as appropriate. [Explanation of Symbols]

[0061] 10 Gas Nozzles 11 Gas supply port 12 Gas outlet 13 Nozzle holes 20 Reaction vessel 21 Container body 22 Lid member 100 Plasma devices W board

Claims

1. A yttrium oxide sintered body, It mainly consists of yttrium oxide, Contains 0.5 wt% to 1.0 wt% of zirconium oxide. It contains a metallic element different from both yttrium and zirconium, and the total content of the metallic elements other than yttrium and zirconium is 500 ppm or less. A yttrium oxide sintered body characterized by containing both Ca and Na as the aforementioned metal elements.

2. The yttrium oxide sintered body according to claim 1, characterized in that the content of Si, Ca, and Na among the aforementioned metal elements is 150 ppm or less for each.

3. A component for a semiconductor manufacturing apparatus, characterized by comprising a yttrium oxide sintered body as described in claim 1 or claim 2.

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