JPH0822798B2 - Crystal growth method - Google Patents
Crystal growth methodInfo
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- JPH0822798B2 JPH0822798B2 JP61204683A JP20468386A JPH0822798B2 JP H0822798 B2 JPH0822798 B2 JP H0822798B2 JP 61204683 A JP61204683 A JP 61204683A JP 20468386 A JP20468386 A JP 20468386A JP H0822798 B2 JPH0822798 B2 JP H0822798B2
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- melt
- crystal
- magnetic field
- oxygen
- crucible
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- Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は円柱状のシリコン単結晶等の結晶の成長方法
に関し、更に詳述するとチョクラルスキー法による結晶
の成長中に結晶の周方向に回転する回転磁場と縦磁場と
を共に融液に印加することにより実効偏析係数を向上せ
しめ、また低酸素の結晶を成長させ得る方法を提供する
ものである。TECHNICAL FIELD The present invention relates to a method for growing a crystal such as a cylindrical silicon single crystal, and more specifically, in the circumferential direction of the crystal during the crystal growth by the Czochralski method. It is intended to improve the effective segregation coefficient by applying both a rotating rotating magnetic field and a longitudinal magnetic field to a melt, and to provide a method capable of growing a low oxygen crystal.
シリコン単結晶等の結晶を成長させる方法として、チ
ョクラルスキー法による結晶の成長中に、融液に静磁場
を印加する方法がある（日経エレクトロニクス1980.9.1
5、ULSI1985.8）。この方法は真空雰囲気下のるつぼ内
の融液に、主方向が水平方向である磁場を印加する横磁
場法と、主方向が鉛直方向、つまり結晶引上げ方向であ
る磁場を印加する縦磁場法とに大別される。As a method of growing a crystal such as a silicon single crystal, there is a method of applying a static magnetic field to the melt during the crystal growth by the Czochralski method (Nikkei Electronics 1980.9.1.
5, ULSI1985.8). This method uses a transverse magnetic field method for applying a magnetic field whose main direction is a horizontal direction to a melt in a crucible under a vacuum atmosphere, and a vertical magnetic field method for applying a magnetic field whose main direction is a vertical direction, that is, a crystal pulling direction. It is roughly divided into.
第10図は後者の方法に使用する結晶成長装置の縦断面
図であり、縦磁場法は真空容器101内においてヒータ102
により加熱される石英製のるつぼ103内の融液104に、真
空容器101の外側に軸心を鉛直方向として設けられたコ
イル106により鉛直方向の磁場163を印加した状態で、そ
の融液104を上方に引上げて凝固させて円柱状の結晶105
を成長させる方法である。FIG. 10 is a vertical cross-sectional view of the crystal growth apparatus used in the latter method.
The melt 104 in the quartz crucible 103 heated by the, while the vertical magnetic field 163 is applied by the coil 106 provided with the axial center as the vertical direction outside the vacuum vessel 101, the melt 104 Columnar crystal 105 pulled upward to solidify
Is a way to grow.
そして、縦磁場法による場合には鉛直方向の磁場によ
りそれがない場合と比べて実効偏析係数が高くなるとい
う効果がある。The longitudinal magnetic field method has the effect of increasing the effective segregation coefficient due to the vertical magnetic field as compared with the case without it.
第11図は、縦磁場の強さを変えて製造した単結晶につ
いてその単結晶の成長方向（ｚ方向）磁場強度Bz/T（横
軸）と、単結晶へ添加したドーパント（リン）の実効偏
析係数Ke〔Ｐ〕（縦軸）との関係を示したグラフであ
り、図中の●印，▲印は夫々結晶方位が〔100〕である
単結晶を結晶回転数10rpm,15rpmで成長させた場合、△
印は結晶方位が〔111〕である単結晶を結晶回転数15rpm
で成長させた場合を示す。この図より理解される如く、
Bz/T＝０、つまり縦磁場を印加しない場合にはKe〔Ｐ〕
が0.35と小さいがBz/Tを増大させていくとKe〔Ｐ〕が増
大していき、Bz/T＝0.1のときにはそれが0.6となる。FIG. 11 shows the magnetic field strength B z / T (horizontal axis) of the single crystal grown in a single crystal grown by changing the strength of the longitudinal magnetic field and the dopant (phosphorus) added to the single crystal. It is a graph showing the relationship with the effective segregation coefficient K e [P] (vertical axis). The ● and ▲ marks in the figure represent single crystals with crystal orientations of [100] at crystal rotation speeds of 10 rpm and 15 rpm, respectively. When grown, △
The mark indicates a single crystal with a crystal orientation of [111] at a crystal rotation speed of 15 rpm.
Shows the case of growing with. As understood from this figure,
B z / T = 0, that is, K e [P] when no longitudinal magnetic field is applied
Is as small as 0.35, K e [P] increases as B z / T is increased, and becomes 0.6 when B z / T = 0.1.
これは、結晶の回転によって生じる融液の対流（マラ
ンゴニ流）が縦磁場により抑制され、このため結晶の成
長に伴って融液中に放出される溶質原子の移動に寄与す
る主な駆動力が拡散だけとなるからであるといわれてい
る。This is because the convection of the melt (Marangoni flow) caused by the rotation of the crystal is suppressed by the longitudinal magnetic field, and therefore the main driving force that contributes to the movement of solute atoms released into the melt as the crystal grows. It is said that it is only diffusion.
第12図は、縦磁場法によりシリコン単結晶を製造する
場合のBz/T（横軸）と、シリコン単結晶中の酸素量
〔Oi〕1018cm-3（縦軸）との関係を示したグラフであ
り、図中の破線及び一点鎖線は夫々磁場を印加しない場
合及び横磁場法により製造する場合夫々の酸素量の上限
値を示している。なお、図中の●，▲，△印は第11図と
同様であり、■印は結晶方位が〔100〕である単結晶を
結晶回転数25rpmで成長させた場合、○印，□印は夫々
結晶方位が〔111〕である単結晶を結晶回転数10rpm,25r
pmで成長させた場合を示す。なお、るつぼ回転数ncは0.
5rpmと2rpmとの２通りである。この図により縦磁場法に
よる場合は結晶中の酸素量が他の方法に比して高くなる
現象があると言える。Figure 12 shows the relationship between B z / T (horizontal axis) and the amount of oxygen [O i ] 10 18 cm -3 (vertical axis) in a silicon single crystal when a silicon single crystal is produced by the vertical magnetic field method. The broken line and the alternate long and short dash line in the figure show the upper limit values of the oxygen amount when no magnetic field is applied and when manufactured by the transverse magnetic field method, respectively. The symbols ●, ▲, and △ in the figure are the same as those in Fig. 11, and the symbols ■ indicate the symbols ○ and □ when a single crystal with a crystal orientation of [100] was grown at a crystal rotation speed of 25 rpm. A single crystal with a crystal orientation of [111] was rotated at 10 rpm and 25 r
Shown when grown in pm. The crucible rotation speed n c is 0.
There are two types, 5 rpm and 2 rpm. From this figure, it can be said that there is a phenomenon that the amount of oxygen in the crystal is higher in the case of the longitudinal magnetic field method than in the other methods.
本発明はこの現象が生ずる理由を解明することによっ
て、結晶中の酸素濃度の低減化を計ることが可能である
縦磁場法による結晶成長方法を提供することを目的とす
る。It is an object of the present invention to provide a crystal growth method by a longitudinal magnetic field method, which can reduce the oxygen concentration in the crystal by elucidating the reason why this phenomenon occurs.
本発明に係る結晶成長方法は、結晶の引上方向に沿う
直流磁場を融液に印加しつつ円柱状の結晶を引上げるチ
ョクラルスキー法による結晶成長方法において、融液の
上表面で外方から結晶下に向かう融液の流動を得べく、
結晶の径方向外向きであって、且つ融液の深さの中央部
で回転流動が最も大きく、融液の上表面及び底面で小さ
い融液の流動を生ぜしめる結晶の周方向に回転する回転
磁場を、前記直流磁場と共に融液に印加することを特徴
とする。The crystal growth method according to the present invention is a crystal growth method by the Czochralski method in which a columnar crystal is pulled up while applying a direct-current magnetic field along the crystal pulling direction to the melt. In order to obtain the flow of melt from below to the crystal,
Rotation in the circumferential direction of the crystal that is outward in the radial direction of the crystal and that has the largest rotational flow at the center of the depth of the melt and produces a small melt flow at the top and bottom surfaces of the melt. A magnetic field is applied to the melt together with the DC magnetic field.
まず、本発明の原理について説明する。 First, the principle of the present invention will be described.
第12図に明らかな如く磁場を印加しない方法による場
合に比して横磁場法による場合の方が結晶中の酸素濃度
が低い。横磁場を印加した場合に酸素濃度が低い理由
は、従来以下のように説明されてきた。即ち、結晶中の
酸素の供給源はるつぼであり、これから溶出した酸素も
しくはSiOが対流によって融液表面を経て結晶直下へ入
り込み、結晶へ取込まれる。As is clear from FIG. 12, the oxygen concentration in the crystal is lower in the case of the transverse magnetic field method than in the case of not applying a magnetic field. The reason why the oxygen concentration is low when a transverse magnetic field is applied has been conventionally explained as follows. That is, the supply source of oxygen in the crystal is the crucible, and oxygen or SiO eluted from the crucible enters into the crystal directly below the crystal through the surface of the melt by convection.
横磁場を印加した場合には融液表面での対流が抑制さ
れ、融液表面にある時間が長くなり、この間に酸素もし
くはSiOが蒸発し、その結果、結晶直下へ流れ込む酸素
量が少なくなるというのである。When a transverse magnetic field is applied, convection on the surface of the melt is suppressed, the time on the surface of the melt becomes longer, and during this time oxygen or SiO evaporates, and as a result, the amount of oxygen flowing directly under the crystal decreases. Of.
ところが、縦磁場を印加する場合にも融液表面の対流
が抑制されるから縦磁場法による場合にも酸素濃度が低
くなる筈であるが、実際には第12図に明らかな如くその
酸素濃度が高い。つまり、上記理由では縦磁場法の場合
の現象解明は不可能である。そこで、数値解析手法を用
いて縦磁場法による場合の高酸素濃度化に原因を解明す
ることを試みた。第１図は融液静止を初期条件とし、マ
ランゴニ流の発生原因である表面張力の温度係数ＫをＫ
＝0.1mJ/m-2K-1として計算により求めた融液の流速（破
線）と結晶中の酸素濃度（実線）とを示すグラフであ
り、横軸に時間（秒）をとり、縦軸に酸素濃度と流速
（ms-1）とをとって示している。なお、融液の流速は第
２図（イ）を付して示す如く結晶軸から100mm,融液表面
下0.05mmの位置の半径方向（軸心向）の流速（Vr）であ
り、また酸素濃度は結晶軸上の値であって飽和濃度を1.
0として正規化して示している。However, even if a longitudinal magnetic field is applied, the convection on the melt surface is suppressed, so the oxygen concentration should be low even when the longitudinal magnetic field method is used. Is high. In other words, it is impossible to elucidate the phenomenon in the case of the longitudinal magnetic field method for the above reasons. Therefore, we tried to elucidate the cause of the high oxygen concentration in the case of the longitudinal magnetic field method by using the numerical analysis method. Figure 1 shows the temperature coefficient K of the surface tension, which is the cause of the Marangoni flow, as K
= 0.1 mJ / m -2 K -1 is a graph showing the melt flow velocity (broken line) and the oxygen concentration in the crystal (solid line), where the horizontal axis represents time (seconds) and the vertical axis represents The oxygen concentration and the flow velocity (ms −1 ) are shown in FIG. The flow velocity of the melt is the radial velocity (axial direction) at a position of 100 mm from the crystal axis and 0.05 mm below the surface of the melt as shown in Fig. 2 (a), and oxygen The concentration is the value on the crystal axis, and the saturation concentration is 1.
It is normalized and shown as 0.
この図より理解される如く、時刻ｔ＝０、つまり融液
静止時（ａ点）には融液中の酸素濃度は飽和レベルに達
しており、流速が増加するにつれて酸素濃度は低下して
いき、最小の値0.001程度（ｂ点）となった後、増加し
ていき、例えば0.95のとき（ｃ点）に0.02程度となる。As understood from this figure, at time t = 0, that is, when the melt is at rest (point a), the oxygen concentration in the melt reaches the saturation level, and the oxygen concentration decreases as the flow velocity increases. After reaching the minimum value of about 0.001 (point b), it increases, and becomes about 0.02 at 0.95 (point c), for example.
このような特性を示す理由は以下のように推定され
る。第３図の（イ），（ロ），（ハ）は第１図のa,c,b
夫々のときの融液対流の状態を示す模式図である。融液
対流の速さが遅いａの場合には第３図（イ）に示す如く
融液４中の酸素が結晶５の直下を除く融液表層部から蒸
発し、その融液表層部に低酸素域ｈ（ハッチング部）が
形成されるが、マランゴニ流の速度が遅いので低酸素域
ｈの融液が結晶直下部分へ流入しにくく、結晶直下部分
では低酸素域ｈ以外の部分での対流にて高酸素域とな
り、その結果、製造された単結晶は高酸素濃度となる。The reason for exhibiting such characteristics is estimated as follows. (A), (b), and (c) of FIG. 3 are a, c, and b of FIG.
It is a schematic diagram which shows the state of melt convection at each time. When the melt convection speed is slow a, as shown in FIG. 3 (a), oxygen in the melt 4 evaporates from the melt surface layer except immediately below the crystal 5, and the melt surface layer is low. Oxygen region h (hatching part) is formed, but since the Marangoni flow velocity is slow, it is difficult for the melt in the low oxygen region h to flow into the part directly below the crystal, and in the part directly below the crystal, convection occurs in parts other than the low oxygen region h. In the high oxygen region, the resulting single crystal has a high oxygen concentration.
また、融液の対流が速いｃの場合には、第３図（ロ）
に示す如くるつぼ壁近傍の高酸素域の融液が酸素の蒸発
が十分に行われないままに結晶直下部分へ流入するの
で、結晶中の酸素濃度は低レベルとはならない。Further, when the convection of the melt is fast c, FIG.
As shown in (3), the melt in the high oxygen region near the crucible wall flows into the portion directly below the crystal without sufficient oxygen evaporation, so the oxygen concentration in the crystal does not reach a low level.
そして、融液の対流速度が適当なｂの場合には第３図
（ハ）に示す如く酸素蒸発による低酸素域の形成とその
領域の融液の結晶直下への流入がバランスよく同時に進
行するため、結晶直下部分に低酸素域ｈが形成され、製
造する結晶の低酸素濃度化が可能となる。つまり、融液
表面の水平方向の対流速度を適当な値にすることにより
結晶中の酸素濃度を低減できるのである。When the convection velocity of the melt is appropriate b, the formation of the low oxygen region due to oxygen evaporation and the inflow of the melt into the region just below the crystal in a well-balanced manner simultaneously proceed as shown in FIG. Therefore, the low oxygen region h is formed immediately below the crystal, and the oxygen concentration of the manufactured crystal can be reduced. That is, the oxygen concentration in the crystal can be reduced by setting the horizontal convection velocity on the surface of the melt to an appropriate value.
横磁場法の場合は磁力線の方向と平行方向の融液表層
における水平方向流動を抑制できないため、ある程度の
流動が残存してｂ点の如く酸素濃度が極小値を示す速度
値付近の対流が生じていたものと推定される。これに対
して縦磁場法の場合には磁力線の方向とマランゴニ流の
駆動方向が直交し水平方向流動に抑制が働くため、磁場
増加とともに対流は非常に抑制されると考えられる。即
ちａ点の如き遅い対流を生じていたと考えられる。In the case of the transverse magnetic field method, horizontal flow in the melt surface layer parallel to the direction of the magnetic field lines cannot be suppressed, so some flow remains and convection occurs near the velocity value at which the oxygen concentration has a minimum value as at point b. It is presumed that On the other hand, in the case of the longitudinal magnetic field method, the direction of the lines of magnetic force and the driving direction of the Marangoni flow are orthogonal to each other, and the horizontal flow is suppressed. Therefore, it is considered that convection is significantly suppressed as the magnetic field increases. That is, it is considered that a slow convection such as a point was generated.
第13図は磁場を印加しないチョクラルスキー法により
場合（破線）と縦磁場法による場合（実線）との融液表
面温度の測定結果を示し、後者の方がるつぼ軸心とるつ
ぼ側壁との温度差が大であって縦磁場法が表面対流が遅
いことが裏付けられる。Figure 13 shows the measurement results of the melt surface temperature in the case of the Czochralski method without applying a magnetic field (broken line) and in the case of the longitudinal magnetic field method (solid line), with the latter being the center of the crucible and the side wall of the crucible. This proves that the longitudinal magnetic field method has a large temperature difference and the surface convection is slow.
従って、縦磁場法により単結晶の低酸素化を図るには
結晶直下の融液部分での対流を抑制して縦磁場法の本来
の目的である実効偏析係数の向上を図る一方で、またそ
れ以外の融液表層部でこれより速い適当な流速の水平方
向の対流を融液に生ぜしめる必要がある。Therefore, in order to lower the oxygen content of a single crystal by the longitudinal magnetic field method, convection in the melt portion immediately below the crystal is suppressed to improve the effective segregation coefficient, which is the original purpose of the longitudinal magnetic field method. It is necessary to generate horizontal convection at an appropriate flow velocity higher than this in the surface layer of the melt other than the above in the melt.
このため、本発明は直流の縦磁場を融液に印加すると
共に、結晶の周方向に回転する回転磁場を融液に印加す
る。Therefore, in the present invention, a direct-current longitudinal magnetic field is applied to the melt, and a rotating magnetic field rotating in the circumferential direction of the crystal is applied to the melt.
即ち、回転磁場を融液に印加する場合には次の作用が
ある。回転磁場により融液には回転力Ｆφが発生する
が、その回転力は鉛直方向の誘導電流Jzとるつぼ半径方
向の磁場Brとの積（Jz・Br）となることが知られてお
り、融液の上表面，底面及びるつぼの側壁を横切る方向
の電流は生じない。従って、発生する回転力は融液の上
表面，底面部で０となると考えられる。これらを境界条
件として融液に与えられる回転磁場の電磁力分布を、る
つぼの半径方向位置（ｒ）を変えて計算により求めた結
果をプロットした図を第４図に示す。第４図において横
軸は回転力をとり、縦軸は融液深さをとっている。That is, when a rotating magnetic field is applied to the melt, it has the following effects. A rotating force Fφ is generated in the melt by the rotating magnetic field, and it is known that the rotating force becomes a product (J z · B r ) of the induced current J z in the vertical direction and the magnetic field B r in the radial direction of the crucible. Therefore, no electric current is generated across the upper and lower surfaces of the melt and the side walls of the crucible. Therefore, it is considered that the rotational force generated becomes zero on the upper surface and the bottom surface of the melt. FIG. 4 shows a plot of the results obtained by calculating the electromagnetic force distribution of the rotating magnetic field applied to the melt with these as boundary conditions and changing the radial position (r) of the crucible. In FIG. 4, the horizontal axis represents the rotational force and the vertical axis represents the melt depth.
左側の分布はｒが0.05mの位置、中央の分布はｒが0.1
mの位置、右側の分布はｒが0.15mの位置の場合である。The distribution on the left is r = 0.05m, and the distribution in the center is r = 0.1.
The distribution on the right side of the m position is for the position of r of 0.15 m.
この図より理解される如く融液の回転流動も融液の深
さ位置中央部で最大、融液の上表面，底面で最小とな
り、その結果、第５図（２点鎖線は融液の流れを示す）
に示す如く融液の深さ方向で遠心力の差が生じて融液の
深さ方向中央部では外向きとなるような流動が発生し、
この流動により融液の上表面ではるつぼ側壁からるつぼ
軸心に向かう流動が生じる。このため、酸素の蒸発によ
り低酸素濃度となった結晶直下を除く融液表層部の融液
が結晶直下の融液部分に流入し、低酸素濃度の結晶を成
長させることが可能となる。また、結晶直下の融液上表
面部分では回転流動が弱く、縦磁場も印加するので、拡
散層が厚く安定となるので、実効偏析係数は向上する。As can be understood from this figure, the rotational flow of the melt also becomes maximum at the center of the depth position of the melt and minimum at the top and bottom surfaces of the melt, and as a result, the flow of the melt is shown in FIG. Indicates)
As shown in, a difference in centrifugal force is generated in the depth direction of the melt, and a flow is generated that is outward at the center of the melt in the depth direction.
This flow causes a flow from the crucible side wall to the crucible axis on the upper surface of the melt. For this reason, the melt in the surface layer portion of the melt excluding the portion immediately below the crystal, which has a low oxygen concentration due to the evaporation of oxygen, flows into the molten portion immediately below the crystal, and a crystal with a low oxygen concentration can be grown. Further, since the rotational flow is weak in the upper surface portion of the melt just below the crystal and a longitudinal magnetic field is applied, the diffusion layer becomes thick and stable, and the effective segregation coefficient is improved.
以下に本発明を図面に基づき具体的に説明する。第６
図は本発明の実施状態を示す模式的側断面図であり、図
中１はチャンバー１を示す。チャンバー１は軸長方向を
垂直とした略円筒状の真空容器であり、上面中央部には
矢符方向に所定速度で回転する引上げチャック10の回転
軸10′がエアシールドされて貫通されている。The present invention will be specifically described below with reference to the drawings. Sixth
FIG. 1 is a schematic side sectional view showing an embodiment of the present invention, in which 1 indicates a chamber 1. The chamber 1 is a substantially cylindrical vacuum container whose axial direction is vertical, and a rotary shaft 10 'of a pulling chuck 10 which rotates at a predetermined speed in the arrow direction is penetrated through the central portion of the upper surface in an air-shielded manner. .
チャンバー１の底面中央部には、前記引上げチャック
10とは同一軸心で正または逆方向に所定速度で回転する
るつぼ３の支持軸９がエアシールドされて貫通してい
る。支持軸９の先端には黒鉛製るつぼ３′がその内側に
石英（SiO2）製るつぼ３を嵌合する状態で取り付けられ
ている。At the center of the bottom of the chamber 1, the pulling chuck
The support shaft 9 of the crucible 3 which rotates at a predetermined speed in the forward or reverse direction with the same axis as that of 10 is air-shielded and penetrates. A graphite crucible 3 ′ is attached to the tip of the support shaft 9 with the quartz (SiO 2 ) crucible 3 fitted therein.
るつぼ３の回転域のやや外側位置には抵抗加熱式のヒ
ータ２が、その更に外側のチャンバー１との間の位置に
は熱遮蔽体21が夫々同心円筒状に配設されている。A resistance heating type heater 2 is arranged at a position slightly outside the rotational range of the crucible 3, and a heat shield 21 is concentrically arranged at a position between the crucible 3 and the chamber 1 further outside thereof.
るつぼ３内には単結晶用原料が装入されるようになっ
ており、原料はヒータ２の加熱により溶融されて融液４
となる。A raw material for a single crystal is charged into the crucible 3, and the raw material is melted by heating the heater 2 to form a melt 4
Becomes
上記引上げチャック10にはシード（結晶成長の核とな
る単結晶）が取付けられ、このシードをチャック10によ
り降下させて融液４に接触させたのち引上げることによ
り結晶５を成長させるようになっている。A seed (a single crystal that serves as a nucleus for crystal growth) is attached to the pulling chuck 10, and the seed is lowered by the chuck 10 to come into contact with the melt 4 and then pulled to grow the crystal 5. ing.
上記チャンバー１の側面外側には２つのコイル61,6
2、例えばヘルムホルツ型ソレノイドコイルがチャンバ
ー１と同心状にこの順に上側から適長離隔して設けられ
ており、コイル61,62には図示しない電源から直流電流
が通電されるようになっている。コイル61,62は夫々同
方向の縦磁場を発生し、融液４にこの縦磁場を印加す
る。Two coils 61, 6 are provided on the outside of the side surface of the chamber 1.
2. For example, a Helmholtz type solenoid coil is provided concentrically with the chamber 1 in this order at a proper distance from the upper side, and a direct current is supplied to the coils 61 and 62 from a power source (not shown). The coils 61 and 62 generate longitudinal magnetic fields in the same direction, and apply the longitudinal magnetic fields to the melt 4.
２つのコイル61,62の間には環状の回転磁場発生装置
７がチャンバー１を内側に挿通して設けられている。An annular rotating magnetic field generator 7 is provided between the two coils 61 and 62 by inserting the chamber 1 inside.
回転磁場発生装置７は第７図（平面図）に示す如く６
角状となっており、各側面の内側中央部にはコイル巻回
部72…72を突出させて形成されている。コイル巻回部72
…72には三相巻線が施されており、三相巻線は図示しな
い三相交流電源に接続されている。このため、回転磁場
発生装置７は結晶の周方向に回転する回転磁場を発生
し、これを融液４に印加する。The rotating magnetic field generating device 7 has a structure 6 as shown in FIG. 7 (plan view).
It is angular and is formed by projecting coil winding parts 72 ... 72 in the inner center part of each side surface. Coil winding 72
72 has a three-phase winding, and the three-phase winding is connected to a three-phase AC power supply (not shown). Therefore, the rotating magnetic field generator 7 generates a rotating magnetic field rotating in the circumferential direction of the crystal and applies this to the melt 4.
このような磁場雰囲気下で結晶を成長させることによ
り、結晶直下の融液部分では第２図に（ロ）を付して示
す対流が縦磁場により抑制され、また第５図に示す如く
それ以外の融液部分では回転磁場により融液表層部でる
つぼ３の軸心に向かう水平方向の対流が生じる。By growing the crystal in such a magnetic field atmosphere, the convection indicated by (B) in FIG. 2 is suppressed by the longitudinal magnetic field in the melt portion directly below the crystal, and as shown in FIG. In the melt portion, a convection in the horizontal direction toward the axis of the crucible 3 is generated in the melt surface layer portion due to the rotating magnetic field.
このため、融液は第３図（ハ）に示すように、低酸素
域が形成されると共に、その領域の融液が結晶直下へ流
入するため、結晶直下部分に低酸素域が形成され、製造
された結晶は低酸素濃度となる。また、結晶直下部分で
は対流が抑制されているので実効偏析係数が向上する。As a result, as shown in FIG. 3C, the melt has a low oxygen region, and since the melt in that region flows directly under the crystal, a low oxygen region is formed immediately below the crystal. The produced crystals have a low oxygen concentration. Further, since the convection is suppressed in the portion directly below the crystal, the effective segregation coefficient is improved.
なお、上記実施例では回転磁場を発生せしめるべく三
相交流を用いた回転磁場発生装置７を使用しているが、
本発明はこれに限らず他の回転磁場発生手段、例えばリ
ニアモータを使用しても実施できることは勿論である。In the above embodiment, the rotating magnetic field generator 7 using a three-phase alternating current is used to generate the rotating magnetic field.
Of course, the present invention is not limited to this, and can be implemented by using other rotating magnetic field generating means, for example, a linear motor.
また、上記実施例では縦磁場を発生せしめるべく電磁
石を用いているが、本発明はこれに限らず永久磁石を用
いても実施できることは勿論である。Further, in the above embodiment, the electromagnet is used to generate the longitudinal magnetic field, but the present invention is not limited to this, and it is needless to say that the present invention can be implemented by using a permanent magnet.
次に本発明の効果を説明する。結晶方向が〔100〕で
あり、また抵抗率が10Ω・cmとなるようにＰをドープし
た径が５″φのシリコン単結晶を、本発明により製造し
た。なお、製造条件としては縦磁場は200mT,回転磁場は
60Hz,3mTとした。またるつぼの内径:16″φ，るつぼ内
への原料装入重量:30kg,引上速度:1mm・min-1程度，結
晶回転数:25rpm,るつぼ回転数（結晶回転方向と逆方
向）:0.5rpm,結晶の長さ:500〜900mm程度であった。Next, the effect of the present invention will be described. According to the present invention, a silicon single crystal having a crystal orientation of [100] and a diameter of 5 ″ φ doped with P to have a resistivity of 10 Ω · cm was produced according to the present invention. 200mT, rotating magnetic field
60Hz, 3mT. Inner diameter of crucible: 16 ″ φ, weight of raw material charged into crucible: 30 kg, pulling speed: 1 mm min −1 , crystal rotation speed: 25 rpm, crucible rotation speed (direction opposite to crystal rotation direction): 0.5 rpm, length of crystal: about 500 to 900 mm.
第９図は本発明により製造したシリコン単結晶を結晶
の長さ方向に100mmピッチでサンプルを採取し、各サン
プルの電気抵抗率より計算で求めた実効偏析係数と赤外
線吸収法による酸素量測定結果とを示しており、比較の
ために融液に磁場を印加しないチョクラルスキー法によ
る場合（従来例１）の結果と、磁場が200mTの縦磁場法
による場合（従来例２）の結果とを併せて示している。
なお、３つの結果とも３チャージ分の平均値とバラツキ
の範囲を示している。FIG. 9 shows a sample of the silicon single crystal manufactured according to the present invention in the length direction of the crystal at a pitch of 100 mm, and the effective segregation coefficient calculated from the electrical resistivity of each sample and the oxygen content measurement result by the infrared absorption method. For comparison, the results of the Czochralski method without applying a magnetic field to the melt (conventional example 1) and the longitudinal magnetic field method with a magnetic field of 200 mT (conventional example 2) are shown. It is also shown.
Note that all three results show the average value and the range of variation for three charges.
上記実効偏析係数（Ke）の測定は、４端子法によりサ
ンプルの電気抵抗率ρを測定し、その測定値と単結晶中
のＰ濃度とが反比例すると仮定し、下式にて示すPfann
の式 ρ＝ρ０（１−ｇ）1-Ke 但し、 ρ0:単結晶の初期電気抵抗率 g:単結晶の引上げ率 を実測値に適合させることにより行った。The above-mentioned effective segregation coefficient (K e ) is measured by measuring the electrical resistivity ρ of the sample by the 4-terminal method, and assuming that the measured value and the P concentration in the single crystal are inversely proportional,
Ρ = ρ 0 (1-g) 1-Ke where ρ 0 : initial electrical resistivity of single crystal g: pulling rate of single crystal was adapted to the measured value.
この図より理解される如く、従来例２は従来例１と比
べて実効偏析係数を向上できるが、酸素レベルが上昇
し、また両測定値ともバラツキが大きい。実施例では酸
素レベルが従来例１と同程度であるが、実効偏析係数を
向上せしめ得、また酸素レベルについてもこれを低減で
きた。As can be seen from this figure, Conventional Example 2 can improve the effective segregation coefficient as compared with Conventional Example 1, but the oxygen level rises and both measured values have large variations. Although the oxygen level was about the same as that of Conventional Example 1 in the example, the effective segregation coefficient could be improved and the oxygen level could be reduced.
以上詳述した如く、融液の上表面で外方から結晶下に
向かう融液の流動を得べく、結晶の径方向外向きであっ
て、且つ融液の深さの中央部で回転流動が最も大きく、
融液の上表面及び底面で小さい融液の流動を生ぜしめ
る、結晶の周方向に回転する回転磁場を、前記直流磁場
と共に融液に印加することとしているから、結晶中の実
効偏析係数の向上と従来不可能であった酸素濃度の低減
化との両立を計り得、また当然であるが、実効偏析係数
の向上により結晶成長方向の電気抵抗率が一定となり、
これにより結晶から半導体製品を切り出す場合の歩留が
向上する等、本発明は優れた効果を奏する。As described in detail above, in order to obtain the flow of the melt from the outside toward the bottom of the crystal on the upper surface of the melt, the rotational flow is in the radial direction of the crystal and at the center of the depth of the melt. Largest,
Since a rotating magnetic field rotating in the circumferential direction of the crystal that causes a small flow of the melt on the top and bottom surfaces of the melt is applied to the melt together with the DC magnetic field, the effective segregation coefficient in the crystal is improved. It is possible to achieve both the reduction of oxygen concentration, which was impossible in the past, and of course, the electric resistivity in the crystal growth direction becomes constant due to the improvement of the effective segregation coefficient,
As a result, the present invention has excellent effects such as an improvement in yield when cutting semiconductor products from crystals.
第１図は流速及び酸素濃度と時間との関係を示すグラ
フ、第２図はその流速と酸素濃度の算出位置の説明図、
第３図は本発明の原理説明図、第４図は回転磁場を融液
に印加した場合の回転力と融液深さとの関係説明図、第
５図は融液の表層部でのるつぼ軸心へ向かう水平方向の
対流の発生理由の説明図、第６図は本発明の実施状態を
示す模式的縦断面図、第７図は回転磁場発生装置の平面
図、第８図は第７図のVIII−VIII線による断面図、第９
図は本発明の効果説明図、第10図は従来装置の模式的縦
断面図、第11図は磁場強度と実効偏析係数との関係図、
第12,13図は従来技術の問題点の説明図である。 ４……融液、５……結晶、61,62……コイル、７……回
転磁場発生装置FIG. 1 is a graph showing the relationship between flow velocity and oxygen concentration and time, and FIG. 2 is an explanatory diagram of the calculation position of the flow velocity and oxygen concentration,
FIG. 3 is a diagram for explaining the principle of the present invention, FIG. 4 is a diagram for explaining the relationship between the rotational force and the melt depth when a rotating magnetic field is applied to the melt, and FIG. 5 is a crucible shaft at the surface layer of the melt. FIG. 6 is a schematic longitudinal sectional view showing an embodiment of the present invention, FIG. 7 is a plan view of a rotating magnetic field generator, and FIG. 8 is FIG. VIII-VIII sectional view of the ninth
FIG. 10 is an explanatory view of the effect of the present invention, FIG. 10 is a schematic vertical sectional view of a conventional device, and FIG. 11 is a relationship diagram between magnetic field strength and effective segregation coefficient,
12 and 13 are explanatory views of problems of the conventional technique. 4 ... Melt, 5 ... Crystal, 61, 62 ... Coil, 7 ... Rotating magnetic field generator
Claims (1)
加しつつ円柱状の結晶を引上げるチョクラルスキー法に
よる結晶成長方法において、 融液の上表面で外方から結晶下に向かう融液の流動を得
べく、結晶の径方向外向きであって、且つ融液の深さの
中央部で回転流動が最も大きく、融液の上表面及び底面
で小さい融液の流動を生ぜしめる結晶の周方向に回転す
る回転磁場を、前記直流磁場と共に融液に印加すること
を特徴とする結晶成長方法。1. A crystal growth method by the Czochralski method in which a columnar crystal is pulled up while applying a direct-current magnetic field along the crystal pulling direction to the melt. In order to obtain the flowing melt flow, the rotational flow is the largest in the radial direction of the crystal and at the center of the depth of the melt, and a small melt flow is generated on the top and bottom surfaces of the melt. A crystal growing method characterized in that a rotating magnetic field rotating in the circumferential direction of a crystal to be clamped is applied to a melt together with the DC magnetic field.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61204683A JPH0822798B2 (en) | 1986-08-29 | 1986-08-29 | Crystal growth method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61204683A JPH0822798B2 (en) | 1986-08-29 | 1986-08-29 | Crystal growth method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6360193A JPS6360193A (en) | 1988-03-16 |
| JPH0822798B2 true JPH0822798B2 (en) | 1996-03-06 |
Family
ID=16494575
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61204683A Expired - Lifetime JPH0822798B2 (en) | 1986-08-29 | 1986-08-29 | Crystal growth method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0822798B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5196085A (en) * | 1990-12-28 | 1993-03-23 | Massachusetts Institute Of Technology | Active magnetic flow control in Czochralski systems |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6360189A (en) * | 1986-08-28 | 1988-03-16 | Toshiba Corp | Production of semiconductor single crystal |
-
1986
- 1986-08-29 JP JP61204683A patent/JPH0822798B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6360193A (en) | 1988-03-16 |
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