JP4439210B2 - Dummy wafer - Google Patents

Description

【００７２】
表１の結果より、本発明の炭化珪素質焼結体からなり、体積固有抵抗が２×１０^３Ω・ｃｍ以下の試料（Ｎｏ．１〜５）は、吸着力、耐食性が高くレーザー光に対する反射率が７０％以上となり、検出精度が高いことがわかった。
【００７３】
これに対し、炭化珪素質焼結体からなり、体積固有抵抗が２×１０^３Ω・ｃｍを超える試料（Ｎｏ．６〜８）は、吸着力が低下することがわかる。
【００７４】
また、ＣＶＤ法によって形成した炭化珪素からなる試料（Ｎｏ．９）は、吸着力、耐食性は高いものの、反射率が６０％と低く、検出精度が劣る。
【００７５】
さらに、アルミナ質焼結体、シリコンからなる試料（Ｎｏ．１０、１１）は、吸着力、耐食性が劣ることがわかる。
【００７６】
（実施例２）
炭化珪素を主成分とし、その粒界相にアルミニウム及びイットリアの化合物を含み酸化チタンを表１に示す如く添加量にて含有させ、非酸化性雰囲気中において１８００℃から１９５０℃で焼結した後、ロータリー研削盤にて外周部及び中央部の厚みが表２に示す値となるように加工し、ダミーウエハ試料を得た。
【００７７】
このＮｏ．１２〜Ｎｏ．２１までの各試料は、それぞれ１０個製作した。
【００７８】
また、穴部を形成するものは、外径３００ｍｍ、厚み１．２ｍｍの試料にマシニングセンターにて、直径９０ｍｍ、深さ０．５ｍｍの穴部１０を合計７箇所を均一に形成した。
【００７９】
そして、炭化珪素質焼結体からなるダミーウエハの外周部の厚み、中心部の厚み、穴部の有無、質量、反り量及び吸着可否を評価した結果を表２に示す。
【００８０】
外周部と中央部の厚みは、外測マイクロメーターを使用して測定し、また質量計で質量を測定した。また反りの量は３次元測定器にて、平坦な面の外周部と中心部とを測定して反り量を求めた。
【００８１】
また、ダミーウエハを静電チャック上で吸着し、使用可能であるか評価した。吸着が１０個すべて問題無く吸着可能であったものを○、吸着可能であったものが５個〜９個のものを△、吸着可能なものが４個以下のものは、×とした。
【００８２】
【表２】

【００８３】
表２から明らかなように、静電チャックに問題なく吸着させるためには、反りの大きさは０．２ｍｍ以下が望ましいことがわかった。試料（Ｎｏ．１２）は、厚みが大きいため、反り、吸着力に問題ないが質量が重く、シリコンウエハの２倍以上の質量となるため、搬送系のトラブルが生じる可能性が高いことがわかった。
【００８４】
また、試料（Ｎｏ．１３、Ｎｏ．１４）のように、単に厚みを小さくすると反りが０．２ｍｍ以上となり、吸着できないものもあった。
【００８５】
これに対し、周縁部から中央部に向かって厚みが漸増する試料（Ｎｏ．１５〜１８）は、反り量を０．２ｍｍ以下とすることができ、特に、中央部の厚みが１．０〜１．５ｍｍで外周部の厚みが０．５〜０．７５ｍｍである本発明の試料（Ｎｏ．１６、1７）は、軽量化しても反りが０．１ｍｍ以下で、質量もシリコンウエハと同等で吸着も優れたものであることがわかった。
【００８６】
また、試料（Ｎｏ．１８）は、外周部の厚みが中央部の厚みの１／４であり、軽量化は進んでいるものの、外周部が薄すぎて反りが０．２ｍｍと大きいため、吸着ができないものがあった。
【００８７】
また、穴部を有している試料（Ｎｏ．１９〜２１）は、反りを小さくすることができるとともに、軽量化を図れることがわかった。
【００８８】
【発明の効果】
上述のように、本発明によれば、静電チャック及びレーザー検出器をもつ、ＰＶＤ装置等の半導体製造装置において、ダミーウエハの構成部材として、２０〜２５℃における体積固有抵抗２×１０^３Ωｃｍ以下の炭化珪素質焼結体を用いたことにより、静電チャックに十分に吸着されることが可能となる。
【００８９】
また、上記炭化珪素質焼結体が炭化珪素を主成分とし、酸化チタンを３〜７質量％含有させたことにより、体積固有抵抗が２×１０^３Ω・ｃｍ以下の炭化珪素質焼結体を得ることができる。
【００９０】
さらに、波長７００ｎｍのレーザー光に対する反射率が７０％以上であることにより、シリコンウエハと同様にレーザーで感知できるので検知装置を変えなくても使用できる。
【００９１】
また、一方の主面が平坦であり、他方の主面が周縁部から中央部に向かって厚みが漸増しており、中央部の最大厚みが１．０〜１．５ｍｍで外周部の最小厚みが０．５〜０．７５ｍｍであることにより、ダミーウエハの破損を防止して軽量化を図ることができる。また、少なくとも一方の主面に１つ以上の穴部を有しているときには、ダミーウエハの剛性を高め、反りに対する抵抗大きくし、反りを極力抑えることができるとともに、軽量化を図り、搬送時のトラブルを少なくすることができる。
【図面の簡単な説明】
【図１】本発明のダミーウエハを用いたＰＶＤ装置を示す断面図である。
【図２】本発明のダミーウエハの耐食性の評価法を示す正面図である。
【図３】本発明のダミーウエハを示す図面であり、（ａ）は周縁部から中央部に向かって厚みが漸増したダミーウエハを示す平面図であり、（ｂ）は主面に穴部を有するダミーウエハを示す正面図である。
【符号の説明】
１：ＰＶＤ真空チャンバー
２：ターゲット材（Ｃｕ）
３：ダミーウエハ
３ａ：周縁部から中央部に向かって厚みが漸増した面
３ｂ：平坦な面
４：静電チャック
５：レーザー検出器
６：印加電圧器
７：酸（硝酸）
８：容器
９：生成膜（Ｃｕ）
１０：穴部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dummy wafer used in a semiconductor manufacturing apparatus, and more particularly to a dummy wafer that protects an electrostatic chuck surface during operation for determining conditions of an electrostatic chuck and a PVD apparatus having a wafer detection device using laser light.
[0002]
[Prior art]
Conventionally, the dummy wafer 3 is automatically transferred to the wafer holding surface of the electrostatic chuck 4 of the PVD vacuum chamber 1 shown in FIG. 1, for example, and has the same shape as the silicon wafer. The activated metal is guided by the applied voltage device 6 and deposited on the main surface of the dummy wafer 3 placed on the electrostatic chuck 4.
[0003]
In a normal process, a film is formed on a silicon wafer, but the surface of the electrostatic chuck 4 is protected when a new surface of the target material 2 needs to be produced during trial operation or idling of the PVD apparatus having the electrostatic chuck 4. A dummy wafer 3 is required. Conventionally, a silicon wafer is used, which is disposable, or a silicon wafer or a dummy wafer 3 in which an insulator is coated with a conductor is used.
[0004]
As the dummy wafer 3, a ceramic having excellent corrosion resistance and conductivity, a semiconductor in which an insulator is doped with a metal or the like to have a semiconductor resistance, and a silicon carbide ceramic that is a semiconductor are used for a lower resistance. Those doped with other compositions are used.
[0005]
In order to obtain a low-resistance silicon carbide sintered body, 1 to 4% by weight of WSi is contained in a sintered body mainly composed of SiC crystals and containing aluminum and yttria compounds in the grain boundary phase, and is non-oxidizing. It is known that by firing at 1800 ° C. to 1950 ° C. in an atmosphere to obtain a sintered body having a theoretical density of 93% or more, a resistance having a volume resistivity of 10 Ω · cm can be obtained.
[0006]
Thus, as a member for a semiconductor manufacturing apparatus having a lower volume specific resistance value, a member in which a silicon carbide film is formed on the surface of a base material made of carbon or the like by a CVD method has been proposed.
[0007]
Further, a high-purity silicon carbide sintered body has been proposed as a material that hardly generates particles due to reaction products or the like due to plasma irradiation. However, when a silicon carbide sintered body is used, silicon carbide itself is used. Is a hard-to-sinter material, so it is necessary to add an auxiliary agent for promoting B (boron) or oxide-based sintering.⁴Ω · cm to 1 × 10⁸Since it is as high as Ω · cm and a sufficient voltage cannot be supplied between the dummy wafer 3 and the electrostatic chuck 4, a sufficiently stable adsorption force cannot be obtained.
[0008]
Since the normal dummy wafer 3 is used for particle evaluation and process evaluation in a semiconductor manufacturing process and requires high purity, a silicon carbide sintered body cannot be used. However, the protective wafer of the electrostatic chuck 4 of the PVD apparatus as described above does not require such a high purity, and in the PVD apparatus, the target material 2 is basically generated on the wafer, so that it is etched by plasma. Unlike such applications, wafer impurities are not a problem.
[0009]
[Patent Document 1]
Japanese Patent Publication No. 7-37340
[0010]
[Patent Document 2]
JP 2001-200365 A
[0011]
[Patent Document 3]
JP-A-10-64776
[0012]
[Problems to be solved by the invention]
In general, when the dummy wafer 3 is used continuously, the target material 2 accumulates on the surface of the dummy wafer 3 when it is continuously used.
[0013]
When the dummy wafer is formed of an alumina sintered body and a silicon nitride sintered body, there is a problem that the volume resistivity is high and the electrostatic chuck 4 is not attracted.
[0014]
Conventionally, since a silicon wafer is used, the corrosion resistance is very poor, and generally the accuracy and shape of the wafer are remarkably impaired in a few minutes when washed with these acids.
[0015]
In addition, silicon wafers and dummy wafers with insulators coated with conductors can be used for acid cleaning of deposited metal, but at that time, the silicon base material or conductor coatings were also etched and could not be reused. . Various dummy wafers 3 of an alumina sintered body, a silicon nitride sintered body, and a silicon carbide sintered body having high corrosion resistance have been proposed for etching. An alumina sintered body and a silicon nitride sintered body, A problem with silicon carbide sintered bodies is that the volume resistivity is generally high.
[0016]
  Here, Sintered silicon carbideTo the bodyThe generalMethodInMore bakedWith sintered body,Forming silicon carbide on a substrate by CVDWhenIs used.
[0017]
  But,Silicon carbide obtained by firing by a general methodSinteringBody, Volume resistivity is 1 × 10⁴~ 1x10⁸A sufficiently stable adsorptive power as high as Ω · cm could not be obtained. Silicon carbidequalitySince the specific gravity of the sintered body is larger than that of the silicon wafer, it has the same thickness as the silicon wafer.as well asWhen the shape is used, the warpage increases, so a thicker one was used.qualityThere is a problem that the deflection increases depending on the amount, the height of the storage place does not match, and it is damaged.
[0018]
Therefore, the main surface of the dummy wafer has been subjected to lattice-like groove processing for the purpose of preventing warpage after film formation. However, the silicon carbide sintered body has a dimension of about 20% and a volume of about 20% before and after firing. Since it shrinks by 50% and is in a compressed state after firing, the internal stress generated in the firing process is partially released by the groove processing, and there is a problem that the warpage of the dummy wafer 3 itself becomes larger.
[0019]
Further, when it is made of a bulk body of silicon carbide formed by the CVD method, there is a problem that the laser detector 5 for detecting the dummy wafer 3 with the laser beam does not operate normally because the reflectivity with respect to the laser beam is about 50%. It was. Furthermore, the silicon carbide formed on the substrate surface has a volume resistivity of 1 × 10³Although it can be obtained as small as Ω · cm or less, because it is formed by the CVD method, there are few impurities, and crystal grains are deposited relatively regularly, so it is highly permeable to laser light, Since the reflectance is as low as about 50%, there is a problem that the laser detector 5 does not operate normally.
[0020]
The present invention has been made in view of the above-described problems, and the object thereof is a dummy wafer made of a sintered silicon carbide, having high corrosion resistance, high reflectivity with respect to laser light, and easy to be adsorbed to an electrostatic chuck. It is to provide.
[0021]
[Means for Solving the Problems]
  BookThe dummy wafer of the invention is a dummy wafer used in a semiconductor manufacturing apparatusSoAndIt consists of a silicon carbide sintered body containing silicon carbide as a main component and containing 3 to 7% by mass of titanium oxide, one main surface is flat, and the other main surface has a thickness from the outer peripheral portion toward the central portion. The maximum thickness of the central portion is 1.0 to 1.5 mm and the minimum thickness of the outer peripheral portion is 0.5 to 0.75 mm.Volume resistivity at 20-25 ° CBut2 × 10³Ωcm or lessThe reflectivity for a laser beam with a wavelength of 700 nm is 70% or more.IsIt is characterized by.
[0025]
  The dummy wafer of the present invention isIn the above configuration,One or more holes on at least one main surfaceHaveIt is characterized by that.
[0026]
Accordingly, the silicon carbide sintered body is provided with a dummy wafer that has high corrosion resistance, low permeability to laser light, and is easily attracted to an electrostatic chuck.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0028]
A dummy wafer 3 according to the present invention is used in a PVD vacuum chamber apparatus, for example, as shown in a cross-sectional view in FIG. 1. A target material 2 is disposed in the upper portion of the PVD vacuum chamber 1, and an electrostatic chuck 4 is disposed in the lower portion. A voltage is applied between the material 2 and the electrostatic chuck 4 by an applied voltage device 6 during the process. By applying a voltage difference between the target (cathode) and the electrostatic chuck (anode), Ar ions colliding with the target in a high vacuum are knocked out from the atoms constituting the target material 2 by the sputtering phenomenon and face each other. This is a mechanism for depositing on the dummy wafer 3.
[0029]
The electrostatic chuck 4 includes a laser detector 5 that senses the presence of a wafer. In a normal process, a silicon wafer serving as a substrate for a semiconductor chip is disposed on the electrostatic chuck 4 and a film is formed on the silicon wafer. However, it is necessary to expose a new surface of the target material 2 for idling or test operation of the apparatus. In this case, a dummy wafer 3 that protects the surface of the electrostatic chuck 4 is used.
[0030]
The dummy wafer 3 of the present invention is used in a semiconductor manufacturing apparatus such as a PVD apparatus having the electrostatic chuck 4 and the laser detector 5 as described above, and has a volume resistivity of 2 × 10 at 20 to 25 ° C.³It is important to be composed of a silicon carbide sintered body having an Ω · cm or less.
[0031]
  As a result, the electrostatic chuck 4 is sufficiently attracted.IsThus, the dummy wafer 3 and the surface of the electrostatic chuck 4 are in close contact, and the surface of the electrostatic chuck 4 can be sufficiently protected. More preferably, 2.5 × 10²By setting it to Ω · cm or less, a stronger adsorption force can be obtained.
[0032]
  On the other hand, the volume resistivity value is 2 × 10.³If it exceeds Ω · cm, 2 × 10⁸Do not adsorb up to Ω · cmNoHowever, a sufficient attracting force cannot be obtained, and a gap is formed between the dummy wafer 3 and the electrostatic chuck 4 surface, and ionized darget atoms enter and soil the electrostatic chuck 4 surface.Film formationprocessInDecreasing the wafer adsorption forceTheCauses various problems. Furthermore, the volume resistivity value is 2 × 10⁸Ω · cmSuperEll,The dummy wafer 3 is displaced from the surface of the electrostatic chuck 4 so that the suction surface of the electrostatic chuck 4 cannot be protected at all.
[0033]
  In order to obtain a dummy wafer 3 made of a silicon carbide sintered body having the above volume resistivity, silicon carbide is the main component and titanium oxide is obtained.3-7% by massIt can be obtained by inclusion.
[0034]
Further, the attracting surface of the electrostatic chuck 4 to which the dummy wafer 3 or the silicon wafer is attracted has a volume specific resistance value of 1 × 10.⁸~ 1x10¹²By setting the resistance to Ω · cm, an ideal attracting force can be obtained. When the volume specific resistance of the attracting surface of the electrostatic chuck 4 is too small, leakage of the current supplied to the electrostatic chuck 4 occurs. The material to be adsorbed by the electrostatic chuck 4 can be adsorbed as long as it is less than the volume specific resistance of the adsorption surface of the electrostatic chuck 4, but the lower the value, the stronger the adsorbing force.
[0035]
  The volume resistivity value is determined after taking out a test piece of a predetermined shape and printing the electrode.3For the terminal methodThanMeasurementcan do.
[0036]
  The dummy wafer 3 has a reflectance of 70% or more with respect to a laser beam having a wavelength of 700 nm.is important. ThisIt can be used in the same operation as a silicon wafer that is actually used, and the laser light irradiated by the laser detector 5 is reflected by the dummy wafer 3, and the reflection is detected to accurately detect the presence or absence of the dummy wafer 3. can do.
[0037]
On the other hand, if the reflectance is less than 70%, the apparatus for detecting the dummy wafer 3 with the laser beam will not operate normally.
[0038]
A general dummy wafer 3 is formed of silicon carbide by a CVD method on a base material, and since it is high purity and has few impurities, it is polycrystalline but has a uniform crystal orientation, and almost all grain boundaries are observed. Therefore, the light transmittance was high and the reflectance was low. In contrast, since the dummy wafer 3 of the present invention is made of a silicon carbide sintered body, the reflectance can be made high. Since silicon carbide itself is a difficult-to-sinter material, a large amount of sintering aid was required to obtain a dense sintered body, and grain boundaries were formed by the sintering aid of aluminum and yttria. Since silicon carbide crystals are not uniform in size and direction, they have high reflectivity and low light transmittance.
[0039]
  In addition, the reflectance of the above laser light is measured by irradiating a test piece with a wavelength of 700 nm to a test piece of a predetermined shape, measuring the reflected laser light with a spectrophotometer, and comparing the energy difference with the light sourceByFind the reflectanceCan.
[0040]
The dummy wafer 3 preferably has a surface roughness Ra of 0.8 μm or less at least in contact with the surface of the electrostatic chuck 4 so as not to damage the surface of the electrostatic chuck 4 and improve adhesion.
[0041]
In addition, the acid cleaning of the silicon carbide sintered body is likely to be corroded from the edges around the pores in order to facilitate removal of deposits and easy rinsing of the acid cleaning liquid because acid cleaning is repeated. Therefore, it is desirable that the densification is performed with a theoretical density of 93% or more, preferably 95% or more.
[0042]
  Further, the dummy wafer 3 is formed as shown in the front view of FIG.,One main surface 3a gradually increases in thickness from the peripheral edge toward the center.AndThe other main surface 3b is flat.is important.
[0043]
This is because the surface of the target material 2 on which the metal is deposited is the main surface 3a, so that a lightweight dummy wafer 3 with small warpage can be obtained.
[0044]
  The dummy wafer 3 is made of a silicon wafer as much as possiblequalityIt is desirable to be close to the quantity. However, the silicon carbide sintered body has a specific gravity of 2.3 g / cm of the silicon wafer.²The specific gravity of silicon carbide is 3.2 g / cm²Also, when processed to 0.775 mm, for example, like the thickness of the silicon wafer, the cross-sectional shape becomes long, the resistance to bending stress is reduced, and the influence of internal stress on the surface released by grinding becomes stronger. The warpage increases, the contact surface with the electrostatic chuck 4 decreases, and a sufficient holding force cannot be obtained. for that reason,Of the dummy wafer 3ThicknessIsSilicon waferThicker thanNeed toRu.
[0045]
Therefore, by reducing the thickness of the peripheral portion of the main surface 3a as described above, it is possible to prevent warping of the dummy wafer 3 having a specific gravity greater than that of the silicon wafer and to reduce the weight. In addition, although it is easy to generate | occur | produce a curvature in the thin part in a peripheral part, since the position of curvature is near from outer periphery, the influence of the curvature with respect to the whole is small. In particular, since silicon carbide ceramics are fired at a higher temperature than other ceramics, the difference between the firing temperature and room temperature is large, the difference in thermal expansion is large, and the internal stress is also large, so that warpage can be effectively prevented.
[0046]
  Further, in such a dummy wafer 3, the thickness at the center is maximized and the thickness at the outer periphery is minimized.That is, one main surface is flat, and the other main surface is gradually increasing in thickness from the outer peripheral portion toward the central portion.CanImportant,As a result, the dummy wafer 3Lightweight by preventing damageThe figureCan.
[0047]
  Furthermore, the dummy wafer 3CentralThicknessBut1.0-1.5mmsoPerimeterPartMinimum thickness ofBut0.5-0.75mmInCanis important. This is the outer circumferencePartIf the minimum thickness is too thin, it will be easily damaged and warping will increase.PartThickness is 0.5mm or moreThis is necessary and suitable for reducing the weight while preventing the dummy wafer 3 from being damaged..
[0048]
  Such a dummy wafer 3 has a thickness gradually increased toward the center by grinding, for example, a silicon carbide sintered body having an outer diameter of 300 mm and a thickness of 1.2 mm using a cylindrical grinder or a rotary grinder. It can be produced by processing. Further, as shown in the plan view of FIG. 3B, the dummy wafer 3 has at least one hole 10 opened in the main surface 3a on which the metal of the target material 2 is deposited.HaveIt is preferable.
[0049]
  Thislike, Hole 10Have one or moreDepending on the part other than the hole 10soStrengthas well asHas resistance to warpingAs well asA lightweight dummy wafer 3 can be obtained.
[0050]
When the hole 10 is provided so as to open only on the main surface 3a side, the total opening area of all the holes 10 opening on the main surface 3a is preferably 70% or less of the area of the main surface 3a. . This is because when the area of the hole 10 exceeds 70%, the resistance to warpage becomes small.
[0051]
  Furthermore, the dummy wafer 3qualityIn order to reduce the amount and reduce the warpage, the main surface 3b on the opposite side, that is, the electrostatic chuck4The hole 10 that opens to the surface that becomes the suction surface of the electrode may be provided.4It is preferable that the opening area of all the hole portions 10 opened in the main surface 3b be 50% or less of the area of the main surface 3b, and the holes opened in the main surface 3a. It is preferable to provide it so as not to overlap the position of the portion 10.
[0052]
  further, RegulationRegularly forming the hole 10ByTo obtain a dummy wafer 3 that is lighter and less warped.Inwear. Moreover, it is preferable that the distance of the adjacent hole part 10 shall be 5 mm or more. The dummy wafer 3 having such a hole 10 has a total of 7 holes 10 having a diameter of 90 mm and a depth of 0.7 mm, for example, at a machining center of a silicon carbide sintered body having an outer diameter of 300 mm and a thickness of 1.2 mm. It can be obtained by forming the portions uniformly.
[0053]
Next, a method for manufacturing the dummy wafer 3 made of the silicon carbide sintered body of the present invention will be described.
[0054]
  Here, the important thing isAt 20-25 ° CVolume resistivityBut2 × 10³Ω · cm or lessAnd,For laser light with a wavelength of 700 nmReflectivityBut70% or moreWhat isTherefore, as a silicon carbide raw material, titanium oxide (TiO 2) is added to silicon carbide as a main component.₂3-7qualityIt is to be contained in an amount of%. The titanium oxide is 3qualityWhen the amount is less than%, the volume resistivity is 2 × 10³Over Ω · cm, titanium oxide is 7qualityIf the amount exceeds 50%, the silicon carbide sintered body will not be densified and a sufficiently dense body cannot be obtained.
[0055]
  Of titanium oxide in sintered silicon carbidequalityAmount, TiContent ofIs quantified by ICP emission spectrometry,By the following formulaOxideInConversionAskIt was.
Conversion formula: Titanium oxide amount (% by mass) = (Titanium oxide molecular weight / Ti atomic weight) × Ti content (% by mass)
[0056]
  MaAluminum as a sintering aidas well asAdd a predetermined amount of yttria.
[0057]
The obtained raw material powder is molded into a predetermined shape by a cold isostatic press molding method, dry press molding or the like, and fired at a firing temperature of about 1800 to 2000 ° C.
[0058]
Thereafter, the obtained silicon carbide based sintered body is processed into, for example, an outer diameter of 300 mm and a thickness of 1.25 mm by a grinding machine.
[0059]
As shown in FIG. 3A, when the thickness of the center is increased, the thickness is gradually increased toward the center by grinding the obtained sintered body with a cylindrical grinder or a rotary grinder. The hole 10 is formed by a machining center when the hole 10 is formed.
[0060]
  AndIn order to enhance the adsorption effect with the adsorption surface of the electrostatic chuck 4,The flat shown in FIG.surface3bSurface roughnessTheArithmetic mean roughness (Ra) 0.8μm or lessWhenApply lapping so that
[0061]
  by this,Of the flat surface 3bConcavity and convexity due to grinding scratches on the surface are eliminated, adhesion to the electrostatic chuck 4 is improved, and the electrostatic chuck 4 can be used for a long time without being damaged.The
[0062]
【Example】
Example 1
First, silicon carbide is the main component, aluminum and yttria compounds are included in the grain boundary phase, and titanium oxide is added in amounts as shown in Table 1, and sintered at 1800 ° C. to 1950 ° C. in a non-oxidizing atmosphere. Then, processing was performed to an outer diameter of 300 mm and a thickness of 1.25 mm to obtain a dummy wafer sample.
[0063]
Further, as a comparative example, a dummy wafer sample made of silicon carbide formed on the surface of the substrate by a CVD method, an alumina sintered body, and a dummy wafer sample made of silicon were produced.
[0064]
The volume specific resistance value of each sample was obtained by obtaining a test piece having a diameter of 50 mm and a thickness of 2 mm from the sample, printing the electrode, and then measuring the resistance value (three-terminal method).
[0065]
Moreover, in order to measure the reflectance with respect to a laser beam, the test piece was irradiated with a laser beam having a wavelength of 700 nm, the reflected laser beam was measured with a spectrophotometer, and the energy difference from the light source was compared to obtain the reflectance.
[0066]
Furthermore, the following experiments were conducted to evaluate the adsorption force of each sample to the adsorption surface of the electrostatic chuck, the detection accuracy by the laser detector, and the corrosion resistance.
[0067]
As a method of measuring the attractive force, an applied voltage of 600 V is applied to the electrostatic chuck, a test piece having a diameter of 50 mm and a thickness of 2 mm is manufactured from each sample, and the test piece is attracted to the electrostatic chuck surface. The force when the sample was separated was measured, and an adsorption force of 0.02N or more was determined as OK, and a value less than that was determined as NG.
[0068]
In addition, as a method for measuring detection accuracy, after each sample was placed on the suction surface of the electrostatic chuck, a detection test using a laser beam was performed 50 times each, and NG was detected even if it was not detected even once. Was OK.
[0069]
  As an evaluation of corrosion resistance, as shown in FIG.8In HCl concentration 20%, H₂SO₄94% concentration, HNO₃The dummy wafer 3 is immersed in acid 7 having a concentration of 60% and an HF concentration of 46% for 3 days.qualityMeasure the difference in volume and divide the value by the specific gravity of the sample and the number of days and decrease it per dayqualityCalculate the amount, 0.08mg / cm²・ Day or less was OK, and more than that was NG.
[0070]
These results are shown in Table 1.
[0071]
[Table 1]

[0072]
From the result of Table 1, it consists of a silicon carbide sintered body of the present invention, and the volume resistivity is 2 × 10.³It was found that the samples (Nos. 1 to 5) of Ω · cm or less have high adsorption power and corrosion resistance, and reflectivity with respect to laser light is 70% or more, so that the detection accuracy is high.
[0073]
On the other hand, it consists of a silicon carbide sintered body and has a volume resistivity of 2 × 10.³It can be seen that the samples (Nos. 6 to 8) exceeding Ω · cm have a reduced adsorption power.
[0074]
Moreover, although the sample (No. 9) made of silicon carbide formed by the CVD method has high adsorption power and corrosion resistance, the reflectance is as low as 60% and the detection accuracy is poor.
[0075]
Furthermore, it can be seen that the samples (Nos. 10 and 11) made of an alumina sintered body and silicon are inferior in adsorption force and corrosion resistance.
[0076]
  (Example 2)
  After sintering at 1800 ° C. to 1950 ° C. in a non-oxidizing atmosphere containing silicon carbide as a main component, containing aluminum and yttria compounds in the grain boundary phase, and containing titanium oxide in an added amount as shown in Table 1. , Outer periphery with rotary grinderAndDuring ~CentralTable 2 shows the thicknessValueA dummy wafer sample was obtained.
[0077]
This No. 12-No. Ten samples up to 21 were produced.
[0078]
Moreover, what formed a hole part formed uniformly the hole part 10 of diameter 90mm and depth 0.5mm in total seven places in the machining center to the sample of outer diameter 300mm and thickness 1.2mm.
[0079]
  AndSilicon carbideMade of sintered bodyDummy waferPerimeter thickness, center thickness, presence / absence of hole, qualityamount, AntiAmountas well asTable 2 shows the results of evaluating the adsorbability.
[0080]
  PerimeterPartAnd centerPartThe thickness is measured using an external micrometer, andqualityWith a meterqualityThe amount was measured. The amount of warpage is measured with a three-dimensional measuring instrument on the outer periphery of a flat surface.PartAnd heartWhenWas measured to determine the amount of warpage.
[0081]
  Also,Dummy waferOn the electrostatic chuckIs availableevaluated. The case where all 10 adsorbables could be adsorbed without any problem was indicated as ◯, the case where adsorbables were 5 to 9 were indicated as Δ, and the case where adsorbables were 4 or less were indicated as ×.
[0082]
[Table 2]

[0083]
  As is clear from Table 2, the warp size is preferably 0.2 mm or less in order to attract the electrostatic chuck without any problem.I understood it. The sample (No. 12) has a large thickness, so there is no problem in warping and adsorption force.qualityThe amount is heavy, more than twice the silicon waferqualityThis may cause problems with the transport system.I found it expensive.
[0084]
In addition, like the samples (No. 13 and No. 14), when the thickness was simply reduced, the warpage was 0.2 mm or more, and there were some that could not be adsorbed.
[0085]
  On the other hand, the samples (No. 15 to 18) whose thickness gradually increases from the peripheral portion toward the central portion can have a warpage amount of 0.2 mm or less.CentralThicknessIs 1.0-1.5mmPerimeterPartThicknessIs 0.5 to 0.75 mm of the present inventionThe sample (No. 16, 17) has a warp of 0.1 mm or less even if it is reduced in weight.qualityThe amount is the same as that of silicon wafer, and the adsorption is excellent.I understandIt was.
[0086]
  In addition, the sample (No. 18)The outer peripheral thickness isDuring ~CentralThickness ofMino 1 /4AndAlthough the weight reduction is progressing, the outer peripheryPartIs too thinTheSince the warpage is as large as 0.2 mm, there are some that cannot be adsorbed.
[0087]
  Also, the holeHaveSample (No. 19-21)While the warpage can be reduced,Weight savingI found out.
[0088]
【The invention's effect】
  As described above, according to the present invention, in a semiconductor manufacturing apparatus such as a PVD apparatus having an electrostatic chuck and a laser detector, a volume resistivity 2 × 10 at 20 to 25 ° C. as a constituent member of a dummy wafer.³By using a silicon carbide sintered body of Ωcm or less, the electrostatic chuck is sufficiently absorbed.WornPossibleBecome.
[0089]
  The silicon carbide sintered body is mainly composed of silicon carbide, and titanium oxide is used in an amount of 3-7.qualityContaining amount%LetTherefore, the volume resistivity is 2 × 10³A silicon carbide sintered body having an Ω · cm or less can be obtained.
[0090]
Furthermore, since the reflectance with respect to the laser beam having a wavelength of 700 nm is 70% or more, it can be sensed with a laser like a silicon wafer, so that it can be used without changing the sensing device.
[0091]
  Also, one main surface is flat and the other main surface gradually increases in thickness from the peripheral edge toward the center.Have,When the maximum thickness of the central portion is 1.0 to 1.5 mm and the minimum thickness of the outer peripheral portion is 0.5 to 0.75 mm, the dummy wafer can be prevented from being damaged and lightened.Also,One or more holes on at least one main surfaceIf you haveIncreases the rigidity of me wafers, increases resistance to warpage, and minimizes warpageWith, LighterFigureTrouble during transportationSmallloseRube able to.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a PVD apparatus using a dummy wafer of the present invention.
FIG. 2 is a front view showing a method for evaluating the corrosion resistance of a dummy wafer according to the present invention.
3A and 3B are diagrams showing a dummy wafer according to the present invention, wherein FIG. 3A is a plan view showing a dummy wafer whose thickness is gradually increased from a peripheral portion toward a central portion, and FIG. 3B is a dummy wafer having a hole on the main surface. FIG.
[Explanation of symbols]
1: PVD vacuum chamber
2: Target material (Cu)
3: Dummy wafer
3a: Surface whose thickness gradually increases from the peripheral edge toward the center
3b: flat surface
4: Electrostatic chuck
5: Laser detector
6: Applied voltage device
7: Acid (nitric acid)
8: Container
9: Generated film (Cu)
10: Hole

Claims (2)

A dummy wafer used in a semiconductor manufacturing apparatus, comprising a silicon carbide sintered body containing silicon carbide as a main component and containing 3 to 7% by mass of titanium oxide, wherein one main surface is flat and the other main surface Is gradually increased from the outer peripheral portion toward the central portion, the maximum thickness of the central portion is 1.0 to 1.5 mm, the minimum thickness of the outer peripheral portion is 0.5 to 0.75 mm, and 20 to 25 ° C. volume resistivity is not more than 2 × 10 ³ Ω · cm, a dummy wafer reflectivity against a laser beam having a wavelength of 700nm is characterized der Rukoto 70% in. The dummy wafer according to claim 1, wherein at least one main surface has one or more holes.

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