JP4548962B2

JP4548962B2 - Silica glass crucible and silicon single crystal pulling method using the same

Info

Publication number: JP4548962B2
Application number: JP2001091788A
Authority: JP
Inventors: 義行辻; 正徳福井
Original assignee: Japan Super Quartz Corp
Current assignee: Japan Super Quartz Corp
Priority date: 2001-03-28
Filing date: 2001-03-28
Publication date: 2010-09-22
Anticipated expiration: 2021-03-28
Also published as: JP2002284596A

Description

【０００１】
【発明の属する技術分野】
本発明は、ルツボの側壁内表面部分または底部内表面部分を合成石英ガラスによって形成すると共に残余の内表面部分を天然石英ガラスによって形成することにより、引き上げ条件に対応してルツボを選択して使用することができるシリコン単結晶引上用石英ガラスルツボに関する。
【０００２】
【従来の技術】
シリコン単結晶の引き上げ工程において、シリコン融液を入れる石英ガラスルツボが使用されている。この石英ガラスルツボはシリコン融液に不純物が混入しないように高純度であることが求められ、さらにシリコンの融点を上回る高温下で使用されるため、十分な耐熱強度を有することが必要である。この石英ガラスルツボの原料には天然石英と合成石英が用いられており、一般に天然石英は合成石英より純度は低いが耐熱強度に優れており、合成石英は天然石英よりも純度が高い。そこで、ルツボの外側部分を天然石英で形成して高温下でのルツボ強度を高め、一方、シリコン融液に接触するルツボ内側部分は合成石英を用いて形成した石英ガラスルツボが知られている（特開昭５５−９４０９８号公報）。
【０００３】
【発明が解決しようとする課題】
ルツボの外側部分に天然石英を用い、内側部分に合成石英を用いた従来の石英ガラスルツボは、内側の全面が合成石英を原料として形成されている。一方、シリコン単結晶の引き上げ工程において、この石英ガラスルツボは高温下で使用されるが、ルツボの形状や加熱条件によって、ルツボ各部分の温度分布が異なるので内表面の溶損や失透の状態はそれぞれ必ずしも同一ではない。このため、ルツボ内表面の全体を合成石英によって形成したルツボは局部的に内表面部分の溶損程度が大きくなり、これが結晶の乱れを引き起こし、単結晶化率(収率)を低下したり酸素溶解量(Ｏｉ)を増大する原因になる。近年、シリコン単結晶の引上げに用いる石英ルツボは次第に大型化しているが、ルツボが大型化して熱負荷が大きくなるのに伴いこのような問題が一層顕著になる傾向がある。
【０００４】
本発明は、従来の石英ガラスルツボにおける上記問題を解決したものであり、ルツボの側壁内表面部分または底部内表面部分を合成石英ガラスによって形成する一方、残余の内表面部分を天然石英ガラスによって形成することにより、加熱条件に対応してルツボを選択して使用することができるようにし、シリコン単結晶への酸素溶解量が少なく、かつ優れた単結晶化率を達成することができる石英ガラスルツボを提供するものである。
【０００５】
【課題を解決する手段】
すなわち、本発明は以下の構成からなる石英ガラスルツボに関する。
（１）シリコン単結晶の引き上げに用いる石英ガラスルツボにおいて、ルツボの側壁内表面部分または底部内表面部分が合成石英ガラスによって形成されており、残余の内周面部分が天然石英によって形成されていることを特徴とする石英ガラスルツボ。
（２）シリコン単結晶の引き上げに用いる石英ガラスルツボにおいて、ルツボの側壁部から湾曲部を含む範囲の内表面部分が合成石英ガラスによって形成されており、底部内表面部分が天然石英ガラスによって形成されていることを特徴とする石英ガラスルツボ。
（３）シリコン単結晶の引き上げに用いる石英ガラスルツボにおいて、ルツボの底部から湾曲部を含む範囲の内表面部分が合成石英ガラスによって形成されており、側壁内表面部分が天然石英ガラスによって形成されていることを特徴とする石英ガラスルツボ。
【０００６】
【発明の実施の形態】
以下、本発明を図面に示す実施形態に基づいて詳細に説明する。
本発明に係る石英ガラスルツボの構成例を図１および図２に示す。図示するように、本発明の石英ガラスルツボは、シリコン単結晶の引き上げに用いる石英ガラスルツボにおいて、ルツボの側壁内表面部分または底部内表面部分を合成石英ガラスによって形成し、残余の内周面部分を天然石英によって形成したことを特徴とする。
【０００７】
具体的には、図１の石英ガラスルツボは、ルツボの側壁部１０から湾曲部１１を含む範囲の内表面部分が合成石英ガラス２０によって形成されており、底部１２の内表面部分が天然石英ガラス２２によって形成されている。図２の石英ガラスルツボは、ルツボの底部１２から湾曲部１１を含む範囲の内表面が合成石英ガラス２０によって形成されており、側壁１０の内表面部分が天然石英ガラス２２によって形成されている。
【０００８】
このように、本発明の石英ガラスルツボはルツボの側壁部１０または底部１２の何れかの内表面部分が合成石英によって形成されている。なお、内表面部分とはルツボ内表面から適当な厚さを有する部分を云い、通常は溶損深さ(概ね０.７〜１mm)より僅かに厚い部分であり、その縁部は外側の天然石英部分と段差を生じないように、次第に薄く形成すると共に天然石英を厚くすることにより肉厚を一定にするのが好ましい。また、ルツボ内表面部分のうち合成石英で形成する範囲は、ルツボの側壁部１０または底部１２と共に側壁部下端から底部上端に至る湾曲部１１を各々含むものでも良い。すなわち、側壁部１０から湾曲部１１を含む範囲でも良く、あるいは底部１２から湾曲部１１を含む範囲でも良い。なお、この湾曲部１１を含む範囲とは、合成石英で覆われた湾曲部１１の上端または下端がルツボ側壁部１０または底部１２に多少入り込む状態のものをも含む。
【０００９】
ここで、ルツボの側壁部とは上部開口部分から湾曲部上端に至る部分を云い、湾曲部とはルツボ側壁が任意の曲率で内側に傾斜してルツボ底部に連なる部分を云う。またルツボ底部とは湾曲部の下側部分を云い、具体的にはルツボの下側中央部において、概ねルツボの口径Ｒに対して０.５Ｒ〜０.８Ｒの範囲である。因みに、側壁部はいわゆる直胴部分であるが、上部開口部分と同一口径を有する場合に限らず、上方に向かって外開きの傾斜を有する場合も含む。湾曲部の曲率半径ｒとその角度θ（図参照）は底部に対応する範囲で任意であり、湾曲部１１および底部１２の大きさや形状、湾曲状態も限定されない。例えば、丸底ルツボおよび平底ルツボの何れにおいても、ルツボの底部が０.５Ｒ〜０.８Ｒの範囲であるとき、その外側から湾曲部を経てルツボ側壁部全面に至る内表面部分を合成石英ガラスとしても良く、または、この範囲のルツボ底部内表面部分を合成石英ガラスとし、その外側から湾曲部を経てルツボ側壁部全面の内表面部分を天然石英ガラスとしても良い。あるいは、０.５Ｒ〜０.８Ｒの範囲のルツボ底部と湾曲部を合成石英ガラスとし、湾曲部の上側からルツボ側壁部全面の内表面部分を天然石英ガラスとしても良い。
【００１０】
図１に示す構成例において、合成石英によって覆われない底面部分(天然石英部分)の範囲は、例えば、底面半径ｒ’の１／５程度以上であれば良い。また、図２の構成例において、合成石英によって覆われる底部および湾曲分の高さはシリコン融液が引き上げ後に残留する液面程度の高さ以下であれば良い。概ね、この高さは側壁部の高さの約１／３以下である。なお、合成石英によって内表面を覆った部分の全体の肉厚と合成石英を設けない部分の肉厚とは実質的に等しく形成するのが好ましい。また、図１に示す石英ルツボの底部内表面部分を形成する天然石英部分、および図２に示す石英ルツボの側壁内表面部分を形成する天然石英部分は何れの場合もルツボの外側部分を形成する天然石英と一体に形成することができる。
【００１１】
製造方法としては、例えば、回転モールド法による場合、回転するモールドの内表面に天然石英粉を所定厚さに堆積して、ルツボの外側部分の原形とし、次いで、その内周部分または底面部分に限定して合成石英粉を所定厚さに堆積し、このようにルツボ内周面を部分的に原料石英粉の種類を変えて二層構造としたものをアーク溶融等によって加熱することにより全体を一体にガラス化して石英ガラスルツボを得る。この加熱溶融の際に石英紛層内部をモールド側から吸引し、脱気することにより、溶融ガラス層が実質的に気泡を含まない透明ガラス層にすることができる。なお、ルツボの外周部分はシリコン融液に接触しないので、強度および保温効果を高めるために通常は気泡を多く含む不透明ガラス層に形成される。この他に回転モールド法による製造法としては、従来の方法で天然石英によって外周側のルツボを形成した後に、ルツボ内側にアーク炎を挿入し、この炎中に合成石英粉を投入してルツボ内表面に合成石英層を形成して本発明の石英ガラスルツボを製造することができる。
【００１２】
さらに、上記以外の製造方法としては、例えば、ルツボの外形部分を天然石英によって半溶融状態に形成し、合成石英によって予め筒型に形成した側壁内表面部分をこの内側に嵌め合わせ、または、合成石英によって予め皿形に形成した底部内周面部分をルツボ外形部分の底部に嵌め合わせ、半溶融状態またはガラス化した側壁内表面部分ないし底部内表面部分を外側の外形部分と共に加熱溶融してガラス化し、一体化することによって本発明の石英ガラスルツボを得ることができる。
【００１３】
【実施例】
以下、実施例によって本発明を具体的に示す。なお、各例において使用した石英ガラスルツボの性状は表１のとおりである。
【００１４】
【表１】

【００１５】
〔実施例１〕
ルツボの側壁部に面する部分にヒータを有する単結晶引き上げ装置に上記３種類（全面合成石英ルツボ、全面天然石英ルツボ、底部合成石英ルツボ）の石英ガラスルツボを設置して同条件下でシリコン単結晶の引き上げを行った。この結果を表２に示した。各数値は５回の平均値である。なお、底部合成石英ルツボは図２に示す構成を有するものを用いた。
表２に示すように、内表面全体を合成石英で覆ったルツボは、ルツボ側壁部および底部の失透面積は少ないものの、溶損量が多く、従って単結晶化率が低い。また、全体を天然石英によって形成したルツボは、溶損量は少ないが底部の失透面積が大きく、単結晶化率が最も低い。一方、底部内表面を合成石英で覆ったルツボ(本発明品)は、底部と側壁部の失透面積および溶損量が全面天然石英のルツボと全面合成石英のルツボの中間であり、これらの総合的な結果として最も単結晶化率が高い。
【００１６】
【表２】

【００１７】
〔実施例２〕
ルツボの底部に面する部分にヒータを有する単結晶引き上げ装置を用い、底部合成石英ルツボに代えて側壁部を合成石英で覆ったルツボを用いた他は実施例１と同様にしてシリコン単結晶の引き上げを行った。この結果を表３に示した。各数値は５回の平均値である。なお、側壁部合成石英ルツボは図１に示す構成を有するものを用いた。
表３に示すように、内表面全体を合成石英で覆ったルツボは、ルツボ側壁部および底部の失透面積は少ないものの、溶損量が多く、従って単結晶化率が低い。また、全体を天然石英によって形成したルツボは、溶損量は少ないが側壁部の失透面積が大きく、単結晶化率が最も低い。一方、側壁部内表面を合成石英で覆ったルツボ(本発明品)は、底部と側壁部の失透面積および溶損量が全面天然石英のルツボと全面合成石英のルツボの中間であり、これらの総合的な結果として最も単結晶化率が高い。
【００１８】
【表３】

【００１９】
【発明の効果】
本発明の石英ガラスルツボは、シリコン単結晶を引き上げる際に、実施例に示すように、加熱条件に対応して適切な原料構成のルツボを用いることにより優れた単結晶化率を達成することができる。具体的には、加熱源に近接する部分の内表面が天然石英によって形成され、残余の部分が合成石英によって形成されている石英ガラスルツボを用いることにより、加熱源に近接する部分の溶損を抑制して単結晶化率を高めることができる。因みに天然石英部分は溶損量が少ないので含有されている不純物の影響も最小限に抑えることができる。
【図面の簡単な説明】
【図１】本発明に係る石英ルツボの縦断面模式図
【図２】本発明の他の構成例を示す石英ルツボの縦断面模式図
【符号の説明】
１０−側壁部、１１−湾曲部、１２−底部、２０−合成石英、２２−天然石英[0001]
BACKGROUND OF THE INVENTION
In the present invention, the crucible is selected and used in accordance with the pulling conditions by forming the inner surface portion of the side wall or the bottom inner surface portion of the crucible with synthetic quartz glass and the remaining inner surface portion with natural quartz glass. The present invention relates to a quartz glass crucible for pulling a silicon single crystal.
[0002]
[Prior art]
In the pulling process of the silicon single crystal, a quartz glass crucible for containing a silicon melt is used. This quartz glass crucible is required to have a high purity so that impurities are not mixed into the silicon melt. Further, since it is used at a high temperature exceeding the melting point of silicon, it needs to have sufficient heat resistance. Natural quartz and synthetic quartz are used as raw materials for this quartz glass crucible. Generally, natural quartz is lower in purity than synthetic quartz but has excellent heat resistance, and synthetic quartz is higher in purity than natural quartz. Therefore, a quartz glass crucible is known in which the outer part of the crucible is made of natural quartz to increase the crucible strength at high temperature, while the inner part of the crucible that is in contact with the silicon melt is made of synthetic quartz ( JP-A-55-94098).
[0003]
[Problems to be solved by the invention]
In a conventional quartz glass crucible using natural quartz for the outer part of the crucible and synthetic quartz for the inner part, the entire inner surface is formed from synthetic quartz as a raw material. On the other hand, this silica glass crucible is used at high temperatures in the silicon single crystal pulling process, but the temperature distribution of each part of the crucible varies depending on the shape of the crucible and the heating conditions. Are not necessarily the same. For this reason, a crucible in which the entire inner surface of the crucible is formed of synthetic quartz locally increases the degree of melting of the inner surface portion, which causes crystal disturbance and reduces the single crystallization rate (yield) or oxygen This increases the amount of dissolution (Oi). In recent years, quartz crucibles used for pulling silicon single crystals have been gradually increased in size, but such problems tend to become more prominent as the crucibles become larger and the heat load increases.
[0004]
The present invention solves the above-mentioned problems in the conventional quartz glass crucible, and the inner surface portion or the bottom inner surface portion of the side wall of the crucible is formed of synthetic quartz glass, while the remaining inner surface portion is formed of natural quartz glass. This makes it possible to select and use a crucible corresponding to the heating conditions, and a quartz glass crucible that has a small amount of dissolved oxygen in a silicon single crystal and can achieve an excellent single crystallization rate. Is to provide.
[0005]
[Means for solving the problems]
That is, the present invention relates to a quartz glass crucible having the following configuration.
(1) In a silica glass crucible used for pulling up a silicon single crystal, the inner surface part or the inner surface part of the side wall of the crucible is made of synthetic quartz glass, and the remaining inner peripheral surface part is made of natural quartz. A quartz glass crucible characterized by that.
(2) In a silica glass crucible used for pulling up a silicon single crystal, the inner surface portion of the range including the curved portion from the side wall portion of the crucible is formed of synthetic quartz glass, and the inner surface portion of the bottom portion is formed of natural quartz glass. A quartz glass crucible characterized by
(3) In a silica glass crucible used for pulling up a silicon single crystal, the inner surface portion of the range including the curved portion from the bottom of the crucible is formed of synthetic quartz glass, and the inner surface portion of the side wall is formed of natural quartz glass. A quartz glass crucible characterized by
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.
A configuration example of the quartz glass crucible according to the present invention is shown in FIGS. As shown in the figure, the quartz glass crucible of the present invention is a quartz glass crucible used for pulling up a silicon single crystal, wherein the inner wall surface portion or bottom inner surface portion of the crucible is formed of synthetic quartz glass, and the remaining inner circumferential surface portion. Is formed of natural quartz.
[0007]
Specifically, in the quartz glass crucible of FIG. 1, the inner surface portion of the range including the side wall portion 10 of the crucible to the curved portion 11 is formed by the synthetic quartz glass 20, and the inner surface portion of the bottom portion 12 is natural quartz glass. 22 is formed. In the quartz glass crucible of FIG. 2, the inner surface of the range including the bottom portion 12 of the crucible to the curved portion 11 is formed by the synthetic quartz glass 20, and the inner surface portion of the side wall 10 is formed by the natural quartz glass 22.
[0008]
As described above, in the quartz glass crucible of the present invention, the inner surface portion of either the side wall portion 10 or the bottom portion 12 of the crucible is formed of synthetic quartz. The inner surface portion means a portion having an appropriate thickness from the inner surface of the crucible, and is usually a portion slightly thicker than the melt damage depth (generally 0.7 to 1 mm), and its edge portion is an outer natural stone. It is preferable to make the wall thickness constant by forming it gradually thinner and thickening the natural quartz so as not to cause a step difference from the British portion. Further, the range formed of synthetic quartz in the inner surface portion of the crucible may include the curved portion 11 extending from the lower end of the side wall portion to the upper end of the bottom portion together with the side wall portion 10 or the bottom portion 12 of the crucible. That is, the range including the curved portion 11 from the side wall portion 10 may be used, or the range including the curved portion 11 from the bottom portion 12 may be used. The range including the curved portion 11 includes a range in which the upper end or the lower end of the curved portion 11 covered with synthetic quartz slightly enters the crucible side wall portion 10 or the bottom portion 12.
[0009]
Here, the side wall portion of the crucible means a portion from the upper opening portion to the upper end of the curved portion, and the curved portion means a portion where the crucible side wall is inclined inward with an arbitrary curvature and is connected to the bottom portion of the crucible. The crucible bottom refers to the lower portion of the curved portion, specifically, the lower central portion of the crucible is generally in the range of 0.5R to 0.8R with respect to the diameter R of the crucible. Incidentally, although the side wall portion is a so-called straight body portion, the side wall portion is not limited to having the same diameter as that of the upper opening portion, but includes a case in which the side wall portion has an outwardly opening inclination. The radius of curvature r of the bending portion and its angle θ (see the figure) are arbitrary within the range corresponding to the bottom portion, and the size and shape of the bending portion 11 and the bottom portion 12 and the bending state are not limited. For example, in both round-bottom crucibles and flat-bottom crucibles, when the bottom of the crucible is in the range of 0.5R to 0.8R, the inner surface portion extending from the outside to the entire crucible side wall through the curved portion is made of synthetic quartz glass. Alternatively, the inner surface portion of the crucible bottom portion in this range may be made of synthetic quartz glass, and the inner surface portion of the entire crucible side wall portion through the curved portion may be made of natural quartz glass. Alternatively, the crucible bottom portion and the curved portion in the range of 0.5R to 0.8R may be made of synthetic quartz glass, and the inner surface portion of the entire crucible side wall portion from the upper side of the curved portion may be made of natural quartz glass.
[0010]
In the configuration example shown in FIG. 1, the range of the bottom surface portion (natural quartz portion) that is not covered with synthetic quartz may be, for example, about 1/5 or more of the bottom surface radius r ′. In the configuration example of FIG. 2, the height of the bottom portion and the curved portion covered with synthetic quartz may be equal to or less than the height of the liquid level remaining after the silicon melt is pulled up. Generally, this height is about 1/3 or less of the height of the side wall. It is preferable that the entire thickness of the portion whose inner surface is covered with the synthetic quartz and the thickness of the portion where the synthetic quartz is not provided are substantially equal. Further, in any case, the natural quartz portion forming the bottom inner surface portion of the quartz crucible shown in FIG. 1 and the natural quartz portion forming the side wall inner surface portion of the quartz crucible shown in FIG. 2 form the outer portion of the crucible. It can be formed integrally with natural quartz.
[0011]
As a manufacturing method, for example, in the case of the rotational mold method, natural quartz powder is deposited on the inner surface of the rotating mold to a predetermined thickness to form the original shape of the outer portion of the crucible, and then on the inner peripheral portion or the bottom portion. The synthetic quartz powder is deposited in a limited thickness, and the inner peripheral surface of the crucible is changed into a two-layer structure by partially changing the type of raw material quartz powder in this way, and the whole is heated by arc melting or the like. It vitrifies integrally to obtain a quartz glass crucible. During the heating and melting, the inside of the quartz powder layer is sucked from the mold side and degassed, whereby the molten glass layer can be made a transparent glass layer substantially free of bubbles. Since the outer peripheral portion of the crucible does not come into contact with the silicon melt, it is usually formed in an opaque glass layer containing a large amount of bubbles in order to increase the strength and the heat retaining effect. In addition, as a manufacturing method by the rotational mold method, after forming a crucible on the outer peripheral side with natural quartz by a conventional method, an arc flame is inserted inside the crucible, and synthetic quartz powder is put into this flame, and the inside of the crucible is inserted. A quartz glass crucible of the present invention can be manufactured by forming a synthetic quartz layer on the surface.
[0012]
Further, as a manufacturing method other than the above, for example, the outer part of the crucible is formed in a semi-molten state with natural quartz, and the inner surface part of the side wall formed in advance in a cylindrical shape with synthetic quartz is fitted inside this, or the synthetic part is synthesized. The bottom inner peripheral surface portion formed in advance in a dish shape by quartz is fitted to the bottom portion of the crucible outer shape portion, and the glass is obtained by heating and melting the inner surface portion of the side wall or the bottom inner surface portion that is semi-molten or vitrified with the outer outer shape portion. The quartz glass crucible of the present invention can be obtained by integrating and integrating.
[0013]
【Example】
Hereinafter, the present invention will be described specifically by way of examples. The properties of the quartz glass crucible used in each example are shown in Table 1.
[0014]
[Table 1]

[0015]
[Example 1]
The above three types of quartz glass crucibles (full synthetic quartz crucible, full natural quartz crucible, bottom synthetic quartz crucible) are installed in a single crystal pulling device having a heater on the side facing the crucible side, and silicon The crystal was pulled up. The results are shown in Table 2. Each numerical value is an average of 5 times. The bottom synthetic quartz crucible having the configuration shown in FIG. 2 was used.
As shown in Table 2, the crucible whose entire inner surface is covered with synthetic quartz has a small amount of devitrification, although the devitrification area of the crucible side wall and bottom is small, and therefore the single crystallization rate is low. In addition, a crucible formed entirely of natural quartz has a small amount of erosion but a large devitrification area at the bottom and the lowest single crystallization rate. On the other hand, in the crucible whose inner surface is covered with synthetic quartz (product of the present invention), the devitrification area and the amount of erosion of the bottom and side walls are intermediate between the natural quartz crucible and the synthetic quartz crucible. The overall result is the highest single crystallization rate.
[0016]
[Table 2]

[0017]
[Example 2]
A single crystal pulling apparatus having a heater in the portion facing the bottom of the crucible was used in the same manner as in Example 1 except that a crucible having a side wall covered with synthetic quartz was used instead of the bottom synthetic quartz crucible. Raised. The results are shown in Table 3. Each numerical value is an average of 5 times. The side wall synthetic quartz crucible having the configuration shown in FIG. 1 was used.
As shown in Table 3, the crucible whose entire inner surface is covered with synthetic quartz has a small amount of devitrification, although the devitrification area at the crucible side wall and bottom is small, and therefore the single crystallization rate is low. In addition, a crucible formed entirely of natural quartz has a small amount of erosion, but has a large devitrification area at the side wall and the lowest single crystallization rate. On the other hand, the crucible whose inner wall surface is covered with synthetic quartz (the product of the present invention) has a devitrification area and melting amount between the bottom and side walls that are intermediate between the natural quartz crucible and the synthetic quartz crucible. The overall result is the highest single crystallization rate.
[0018]
[Table 3]

[0019]
【The invention's effect】
When pulling up a silicon single crystal, the silica glass crucible of the present invention can achieve an excellent single crystallization rate by using a crucible having an appropriate raw material structure corresponding to heating conditions, as shown in the examples. it can. Specifically, by using a quartz glass crucible in which the inner surface of the portion adjacent to the heating source is formed of natural quartz and the remaining portion is formed of synthetic quartz, the portion near the heating source is melted. It can suppress and can raise the single crystallization rate. Incidentally, since the natural quartz portion has a small amount of melting loss, the influence of impurities contained therein can be minimized.
[Brief description of the drawings]
FIG. 1 is a schematic vertical sectional view of a quartz crucible according to the present invention. FIG. 2 is a schematic vertical sectional view of a quartz crucible showing another configuration example of the present invention.
10-side wall part, 11-curved part, 12-bottom part, 20-synthetic quartz, 22-natural quartz

Claims

In the silica glass crucible used for pulling up the silicon single crystal, the entire crucible outer side from the side wall to the bottom is formed of natural quartz glass, and the inner surface portion in the range including the curved portion from the side wall of the crucible is made of synthetic quartz glass. covered and quartz glass crucible, wherein the natural silica glass at the bottom inside surface portion of the residual is exposed.

In a quartz glass crucible used for pulling up a silicon single crystal, the entire crucible outer side from the side wall to the bottom is formed of natural quartz glass, and the inner surface portion of the range including the curved portion from the bottom of the crucible is covered with synthetic quartz glass. The quartz glass crucible is characterized in that the natural quartz glass is exposed at the remaining inner surface portion of the sidewall in contact with the silicon melt .

3. An edge of the synthetic quartz glass is formed to be thinner so as not to form a step with an outer natural quartz glass, and the thickness is made constant by increasing the thickness of the natural quartz glass. A quartz glass crucible as described in 1.

A method for pulling a silicon single crystal using a single crystal pulling device having a heater in a portion facing the bottom of a quartz glass crucible, wherein the quartz glass crucible is entirely made of natural quartz glass from the side wall to the bottom. An inner surface portion in a range including the curved portion from the side wall portion is covered with synthetic quartz glass, and the natural quartz glass is exposed at the remaining bottom inner surface portion. Crystal pulling method.

A silicon single crystal pulling method using a single crystal pulling apparatus having a heater in a portion facing a side wall of a quartz glass crucible, wherein the quartz glass crucible is entirely natural quartz glass from the side wall to the bottom. The inner surface portion in the range including the curved portion from the bottom is covered with synthetic quartz glass, and the natural quartz glass is exposed at the remaining inner surface portion of the sidewall in contact with the silicon melt. The silicon single crystal pulling method.