JP2016176988A - Low reflection member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low reflection member high in specific rigidity and low in reflection while having high mechanical strength.SOLUTION: There is provided a low reflection member consisting of an alumina sintered body containing oxide of Fe, oxide of Cr, oxide of Ti and oxide of Mn with the content of Al in terms of AlOof 76 mass% or more, sum of the content of Fe in terms of FeOand the content of Cr in terms of CrOof 4 mass% or more and less than 22 mass%, the content of Ti in terms of TiOof 0.3 mass% to 5 mass% and the content of Mn in terms of MnOof 0.1 mass% to 3 mass% based on 100 mass% of the all components constituting the alumina sintered body.SELECTED DRAWING: None

Description

  The low reflection member of the present invention is used for a substrate mounting table as an object to be processed during exposure processing, a wall material in an exposure processing region, or the like in an exposure apparatus or the like in a semiconductor manufacturing process.

  In an exposure apparatus for manufacturing a semiconductor element or a liquid crystal display (FPD), light is reflected on a mounting table of a substrate (for example, a wafer) that is an object to be processed at the time of exposure processing or a wall material in an exposure processing area. In order to suppress and improve exposure accuracy, colored ceramics (hereinafter referred to as a low reflection member) are used.

As such a low reflection member, for example, Patent Document 1 discloses that 55 to 75% by weight or more of alumina (Al ₂ O ₃ ), at least 3% by weight of Si in terms of oxide (SiO ₂ ), and oxidation. A low reflection member is proposed that contains at least 0.4 wt% Ca in terms of product (CaO), at least 0.4 wt% Mg in terms of oxide (MgO), a colorant, and 1% or less impurities. ing.

International Publication No. 2010/095719 Pamphlet

In the example of Patent Document 1, it is described that the highest specific rigidity is 62 GPa · cm ³ / g. However, a substrate mounting table and an exposure processing area which are objects to be processed in the current exposure processing are described. The low reflection member used for the wall material or the like is required to have higher specific rigidity (Young's modulus / density). In addition, even if only the specific rigidity is high, reliability will be lacking. Therefore, this low reflection member has high mechanical strength, high specific rigidity, and low reflectivity. Is required.

  The present invention has been devised to satisfy the above requirements, and an object thereof is to provide a low reflection member having high mechanical strength, high specific rigidity, and low reflectance.

The low reflection member of the present invention is composed of an alumina sintered body containing an oxide of Fe, an oxide of Cr, an oxide of Ti, and an oxide of Mn, and 100 masses of all components constituting the alumina sintered body. %, The content of Al converted to Al ₂ O ₃ is 76% by mass or more, and the total of the content of Fe converted to Fe ₂ O ₃ and the content of Cr converted to Cr ₂ O ₃ is 4% by mass Or less, less than 22% by mass, the content of Ti converted to TiO ₂ is 0.3% to 5% by mass, and the content of Mn converted to MnO ₂ is 0.1% to 3% by mass It is what.

  The low reflection member of the present invention has high mechanical strength, high specific rigidity, and low reflectance.

  Hereinafter, an example of the low reflection member of this embodiment will be described.

The low reflection member of this embodiment is composed of an alumina sintered body containing an oxide of Fe, an oxide of Cr, an oxide of Ti, and an oxide of Mn, and 100 masses of all components constituting the alumina sintered body. %, The content of Al converted to Al ₂ O ₃ is 76% by mass or more, and the total of the content of Fe converted to Fe ₂ O ₃ and the content of Cr converted to Cr ₂ O ₃ is 4% by mass The content obtained by converting Ti into TiO ₂ is 0.3% by mass or more and 5% by mass or less, and the content obtained by converting Mn into MnO ₂ is 0.1% by mass or more and 3% by mass or less.

Since the low reflection member of this embodiment satisfies the above-described configuration, it has high mechanical strength, high specific rigidity, and low reflectance. Here, having high mechanical strength means that it is 280 MPa or more in the three-point bending strength based on JIS R 1601-2008. Further, the specific rigidity of the low reflection member of this embodiment is 78 GPa · cm ³ / g or more, and the reflectance is 8.7% or less in a wavelength region of 350 to 440 nm.

  As described above, the low reflective member of the present embodiment has high mechanical strength, high specific rigidity, and low reflectivity, which constitutes an alumina sintered body that becomes a low reflective member. This is because each component satisfies the content range described above.

Specifically, among 100% by mass of all components constituting the alumina sintered body, Al is changed to Al ₂ O _3.
When the converted content is 76% by mass or more, it mainly contributes to improvement of mechanical strength and specific rigidity in the alumina sintered body. On the other hand, when the content of Al in terms of Al ₂ O ₃ is less than 76% by mass, the mechanical strength and specific rigidity are lowered.

The content, oxides of oxides and Cr of Fe serves as a coloring agent for exhibiting a color tone for suppressing reflection, which the content in terms _Fe 2 _{O 3} and Fe, the Cr _Cr 2 _{O 3} in terms When the total amount is 4% by mass or more and less than 22% by mass, the reflectance can be lowered while suppressing a decrease in specific rigidity. In addition, when the total content described above is less than 4% by mass, the effect of suppressing reflection is small, and when the total content described above is 22% by mass or more, the specific rigidity decreases.

Next, the oxide of Ti contributes to the improvement of the sinterability of the alumina sintered body when the content of Ti converted to TiO ₂ is 0.3% by mass or more and 5% by mass or less. The mechanical strength and specific rigidity of the body can be increased. The content of Ti converted to TiO ₂ is 0.3.
If it is less than mass%, the effect of improving the sinterability of the alumina sintered body is small, and if it exceeds 5 mass%, the effect of suppressing reflection is small.

Further, the Mn oxide has a content of Mn converted to MnO ₂ of 0.1% by mass or more and 3% by mass or less, so that it can function as a colorant and suppress reflection. When the content of Mn converted to MnO ₂ is less than 0.1% by mass, the effect of suppressing reflection is small, and when it exceeds 3% by mass, the mechanical strength decreases.

  Note that the low reflection member of the present embodiment may include a transition metal other than Fe, Cr, Ti, and Mn and an oxide of a transition metal other than Fe, Cr, Ti, and Mn.

  Here, the mechanical strength can be confirmed by preparing a test piece according to JIS R 1601-2008 and measuring the three-point bending strength.

  Next, regarding the specific rigidity, the Young's modulus at room temperature is measured based on the ultrasonic pulse method described in JIS R 1602-1995, the density is measured based on JIS R 1634-1998, and the value of Young's modulus is calculated as the density. It can be calculated by dividing by the value of.

The reflectance in the wavelength range of 350 to 440 nm is measured using, for example, a spectrocolorimeter (CM-3700A manufactured by Konica Minolta) under the conditions of a reference light source D65, a visual field of 10 °, and an illumination diameter of 3 × 5 mm. The reflectance in the wavelength region of 350 to 440 nm may be confirmed.

Furthermore, for the content of each component constituting the alumina sintered body that is a low reflection member, after part of the alumina sintered body is pulverized and the obtained powder is dissolved in a solution such as hydrochloric acid, The content of Al, Fe, Cr, Ti, and Mn was measured using an ICP (Inductively Coupled Plasma) emission spectroscopic analyzer (for example, manufactured by Shimadzu Corporation: ICPS-8100), and Al ₂ O ₃ and Fe ₂ were respectively measured. _{O 3, Cr 2 O 3,} TiO 2, may be converted to MnO _2.

The presence of Al ₂ O ₃ can be confirmed by measuring the alumina sintered body using an X-ray diffractometer. Also, by mapping using an electron beam microanalyzer, the presence of Fe (Cr), Ti, and Mn overlaps with O (oxygen), so that the oxide of Fe, the oxide of Cr, the oxidation of Ti It can be confirmed that the product contains an oxide of Mn.

Next, in the low reflection member of the present embodiment, it is preferable that the content of Mn converted to MnO ₂ is 0.3% by mass or more and 1.5% by mass or less. When such a configuration is satisfied, the reflectance in the wavelength region of 350 to 440 nm can be further reduced while maintaining high mechanical strength.

In the low reflection member of the present embodiment, A / B is 0.3 to 2.9, where A is the content of Fe converted to Fe ₂ O ₃ and B is the content of Cr converted to Cr ₂ O _3. Is preferred. When such a configuration is satisfied, the reflectance in the wavelength region of 350 to 440 nm can be further reduced.

  Moreover, it is suitable for the low reflection member of this embodiment that arithmetic mean roughness (Ra) in the surface is 0.2 μm or more and 1.5 μm or less. When satisfying such a configuration, the reflectance in the wavelength region of 350 to 440 nm can be further reduced. The above-mentioned surface is a surface that is required to have low reflection, and does not include a surface that is not exposed. The arithmetic average roughness (Ra) on the surface can be measured by conforming to JIS B 0601-2001.

  Next, an example of the manufacturing method of the low reflection member of this embodiment is demonstrated.

First, alumina (Al ₂ O ₃ ) powder, iron oxide (Fe ₂ O ₃ ) powder, chromium oxide (Cr ₂ O ₃ ) powder, titanium oxide (TiO ₂ ) powder, and manganese carbonate (MnCO ₃ ) powder And prepare. In addition, calcium carbonate (CaCO ₃ ) powder, magnesium carbonate (MgCO ₃ ) powder, and silicon oxide (SiO ₂ ) powder are prepared as sintering aids.

Next, a predetermined amount of these powders are weighed into primary raw material powders. Specifically, alumina powder is weighed so that the content of Al in terms of Al ₂ O ₃ is 76% by mass out of 100% by mass of all the components constituting the alumina sintered body. Further, among 100% by mass of all components constituting the alumina sintered body, the total of the content of Fe converted to Fe ₂ O ₃ and the content of Cr converted to Cr ₂ O ₃ is 4% by mass or more and 22% by mass. The iron oxide powder and the chromium oxide powder are weighed to be less than%. Further, the titanium oxide powder is weighed so that the content of Ti converted to TiO ₂ is 0.3% by mass to 5% by mass, and the content of Mn converted to MnO ₂ is 0.1% by mass to 3% by mass. Weigh manganese carbonate powder.

And a sintering auxiliary agent is Ca in C out of 100% by mass of all components constituting the alumina sintered body.
aO terms, Mg and MgO conversion, Si and so that 0.4 to 4.4 mass% in total in which SiO ₂ converted, weighed calcium carbonate powder, magnesium carbonate powder and silicon oxide powder.

The content of Mn converted to MnO ₂ is 0.3 mass% or more and 1.5 mass% or less, the content of Fe converted to Fe ₂ O ₃ is A, and the content of Cr converted to Cr ₂ O ₃ is B. When A / B is set to 0.3 to 2.9, the amount of the primary raw material powder may be adjusted.

Next, 1 to 1.5 parts by weight of a binder such as PVA (polyvinyl alcohol), 100 parts by weight of a solvent, and 0.1 to 0.5 parts by weight of a dispersant are added to 100 parts by weight of the weighed primary raw material powder. Weigh and prepare, and put into a stirrer together with the primary raw material powder, and mix and stir to obtain a slurry.

  After that, the slurry is spray dried using a spray drying granulator (spray dryer) to obtain granules, and then a molded body of a predetermined shape is formed by a powder press molding method or an isostatic pressing method (rubber press method). To do.

  Next, the obtained molded body is cut as necessary, and is fired by holding at a maximum temperature of 1350 to 1700 ° C. for a predetermined time using a firing furnace in an air (oxidation) atmosphere to obtain a sintered body. . And the low reflection member of this embodiment can be obtained by grinding the obtained sintered compact.

  In addition, what is necessary is just to adjust with the count of the grindstone at the time of grinding in order that arithmetic mean roughness (Ra) in the surface shall be 0.2 micrometers or more and 1.5 micrometers or less.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

  Samples having different contents of each component constituting the alumina sintered body were prepared, and mechanical strength (three-point bending strength), specific rigidity, and reflectance were measured.

  First, alumina powder, iron oxide powder, chromium oxide powder, titanium oxide powder, and manganese carbonate powder were prepared. Moreover, calcium carbonate powder, magnesium carbonate powder and silicon oxide powder were prepared as sintering aids.

Then, using these powders, the primary raw material powder was weighed so that the content in 100% by mass of all the components constituting the alumina sintered body would be the value shown in Table 1.

Next, 1 part by weight of PVA, 100 parts by weight of solvent, and 0.2 parts by weight of a dispersant are weighed with respect to 100 parts by weight of the weighed primary raw material powder, and placed in a stirrer together with the primary raw material powder. Mixed
The slurry was stirred. Thereafter, the slurry was spray dried using a spray drying granulator (spray dryer) to obtain granules.

Next, the obtained granule was filled in a mold and pressed, and then subjected to cutting to obtain a molded body having a predetermined shape. Next, the obtained molded body was put in a firing furnace and fired in an air atmosphere. Note that the maximum temperature in the firing, depending on the content of TiO _2, in the range of 1400 ° C. to 1600 ° C., if When the content of TiO ₂ is large low temperature side, a small content of TiO ₂ high temperature side Baked at a temperature of

And the grinding | polishing process was given to the surface of the obtained sintered compact, and it was set as the sintered compact of length 50mm * width 50mm * thickness 5mm, and prepared 10 samples of each of these. In the grinding process, the surface is processed so that the arithmetic average roughness (Ra) of each sample is 2 μm, and JIS B 0601-20.
By measuring in accordance with 01, it was confirmed that the arithmetic average roughness (Ra) of the surface of each sample was 2 μm.

  Next, five test pieces having dimensions conforming to JIS R 1601-2008 were cut out from a sintered body having a length of 50 mm × width of 50 mm × thickness of 5 mm, and a three-point bending strength was measured to obtain an average value.

  Also, measure the Young's modulus at room temperature based on the ultrasonic pulse method described in JIS R 1602-1995, measure the density based on JIS R 1634-1998, and divide the Young's modulus value by the density value. Calculated by In addition, the apparent density was used for the density.

  Then, using a spectrocolorimeter (CM-3700A manufactured by Konica Minolta), measurement was performed under the conditions of a reference light source D65, a visual field of 10 °, and an illumination diameter of 3 × 5 mm, and reflection of five samples in a wavelength region of 350 to 440 nm. The average value of the rate was calculated.

Moreover, after pulverizing a part of each sample and dissolving the obtained powder in a solution such as hydrochloric acid, using an ICP emission spectroscopic analyzer (manufactured by Shimadzu Corporation: ICPS-8100), Al, Fe, Cr, The contents of Ti, Mn, Ca, Mg, and Si are measured, and for Al, Fe, Cr, Ti, and Mn, Al ₂ O ₃ , Fe ₂ O ₃ , Cr ₂ O ₃ , TiO ₂ , and MnO _{2, respectively.} Converted into

Regarding Ca, Mg, and Si, in all samples, the content of Ca converted to CaO is 0.15% by mass, the content of Mg converted to MgO is 0.35% by mass, and the content of Si converted to SiO ₂ is It was 0.5 mass%, and it was 1 mass% in total.

  Table 1 shows the results of the content, mechanical strength (three-point bending strength), specific rigidity, and reflectance of each component constituting the alumina sintered body.

As a result of Table 1, sample No. From the comparison between 18 and 25, it was found that when the content of Al in terms of Al ₂ O ₃ was 76% by mass or more, the mechanical strength and specific rigidity were excellent.

Sample No. 2 and No. 23, sample no. 17 and No. From the comparison of 24, the total of the content of Fe converted to Fe ₂ O ₃ and the content of Cr converted to Cr ₂ O ₃ is 4% by mass or more and less than 22% by mass, thereby suppressing a decrease in specific rigidity. However, it turned out that a reflectance becomes low.

And sample no. 6 and no. 19 is fired at the same temperature, but has a large mechanical strength difference, and the content of Ti converted to TiO ₂ is 0.3% by mass or more, which contributes to the improvement of sinterability, It was found that the mechanical strength can be improved. Sample No. 10 and No. From the comparison of 20, it was found that when the content of Ti converted to TiO ₂ is 5% by mass or less, reflection can be suppressed.

In addition, Sample No. 5 and no. 21, Sample No. 8 and sample no. From the comparison of 22, it was found that when the content of Mn converted to MnO ₂ was 0.1% by mass or more and 3% by mass or less, it functions as a colorant and can suppress reflection.

As described above, the sample No. 1 to 18 is that the content of Al converted to Al ₂ O ₃ is 76% by mass or more out of 100% by mass of all the components constituting the alumina sintered body, and the content of Fe converted to Fe ₂ O ₃ The total of Cr and Cr ₂ O ₃ content is 4% by mass or more and less than 22% by mass, Ti is TiO ₂ content is 0.3% by mass or more and 5% by mass or less, and Mn is MnO ₂ equivalent When the content is 0.1 mass% or more and 3 mass% or less, it has a high mechanical strength of 280 MPa or more and a high specific rigidity of 78 GPa · cm ³ / g or more, and reflection in a wavelength region of 350 to 440 nm. The rate was found to be as low as 8.7% or less.

Sample No. 1 in Example 1 Based on 1, 3, 11-14, a sample was prepared by increasing the content of Mn converted to MnO ₂ and decreasing the content of Al converted to Al ₂ O ₃ by the increased amount. (3-point bending strength), specific rigidity and reflectance were measured. In addition, it produced by the method similar to Example 1 except having changed the preparation composition of the primary raw material, sample No. Samples Nos. 26, 31, 37, 42, 47, and 52 are sample No. 1 in Table 1, respectively. Same as 1, 3, 14, 13, 11, 12.

  And while calculating content of each component which comprises an alumina sintered compact by the same method as Example 1, mechanical strength (three-point bending strength), specific rigidity, and reflection are calculated by the same method as Example 1. The rate was measured.

  The results are shown in Table 2.

As shown in Table 2, when the content of Mn converted to MnO ₂ is 0.3% by mass or more and 1.5% by mass or less, the reflectance is low while maintaining high mechanical strength, and the exposure accuracy is further improved. It turned out to be a possible low reflection member.

When the content of Fe converted to Fe ₂ O ₃ is A and the content of Cr converted to Cr ₂ O ₃ is B, a sample in which A / B is the value shown in Table 3 is prepared, and mechanical strength (3 (Point bending strength), specific rigidity and reflectance were measured. In addition, it produced by the method similar to Example 1 except having changed the preparation composition of the primary raw material. 57 is the sample No. in Example 2. 53, sample no. 65 shows the sample No. in Example 2. Same as 48.

And while calculating content of each component which comprises an alumina sintered compact by the same method as Example 1, mechanical strength (three-point bending strength), specific rigidity, and reflection are calculated by the same method as Example 1. The rate was measured.

  The results are shown in Table 3.

  As shown in Table 3, it was found that the reflectance could be further lowered by the value of A / B being in the range of 0.3 to 2.9.

  An alumina sintered body in which the content of each component constituting the alumina sintered body has the values shown in Table 4 is prepared, and the arithmetic average roughness (Ra) on the surface is the value shown in Table 4 The sample No. was subjected to grinding with different counts. 66-81 were obtained. Sample No. 73, sample No. 3 in Example 3. Same as 60, sample no. 81 shows the sample No. in Example 3. Same as 62. Further, the arithmetic average roughness (Ra) was measured in accordance with JIS B 0601-2001.

  And while calculating the content of each component which comprises an alumina sintered compact by the same method as Example 1, the reflectance was measured by the same method as Example 1.

  The results are shown in Table 4.

As shown in Table 4, when the arithmetic average roughness (Ra) on the surface is 0.2 μm or more and 1.5 μm or less, the reflectance becomes 6.0% or less, and the low reflection member that can improve the exposure accuracy can be obtained. I understood.

Claims (4)

It consists of an alumina sintered body containing an oxide of Fe, an oxide of Cr, an oxide of Ti, and an oxide of Mn. Of 100% by mass of all components constituting the alumina sintered body, Al is Al _2. The content in terms of O ₃ is 76% by mass or more, and the total of the content in which Fe is converted into Fe ₂ O ₃ and the content in which Cr is converted into Cr ₂ O ₃ is 4% or more and less than 22% by mass, Low reflection, characterized in that the content of Ti converted to TiO ₂ is 0.3% by mass or more and 5% by mass or less, and the content of Mn converted to MnO ₂ is 0.1% by mass or more and 3% by mass or less. Element. _2. The low reflection member according to claim 1, wherein the content of Mn in terms of MnO ₂ is 0.3% by mass or more and 1.5% by mass or less. The A / B is 0.3 to 2.9, where A is the content of Fe converted to Fe ₂ O ₃ and B is the content of Cr converted to Cr ₂ O _3. Or the low reflection member of Claim 2.   4. The low reflection member according to claim 1, wherein an arithmetic average roughness (Ra) on the surface of the low reflection member is 0.2 μm or more and 1.5 μm or less. 5.