JPH07187889A - Pulling up device for si single crystal which adjusts oxygen control by atmosphere control - Google Patents
Pulling up device for si single crystal which adjusts oxygen control by atmosphere controlInfo
- Publication number
- JPH07187889A JPH07187889A JP33535893A JP33535893A JPH07187889A JP H07187889 A JPH07187889 A JP H07187889A JP 33535893 A JP33535893 A JP 33535893A JP 33535893 A JP33535893 A JP 33535893A JP H07187889 A JPH07187889 A JP H07187889A
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- Japan
- Prior art keywords
- melt
- oxygen concentration
- single crystal
- oxygen
- atmosphere
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Crystals, And After-Treatments Of Crystals (AREA)
- Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、雰囲気制御により融液
表面の酸素濃度を一定に維持し、品質が安定したＳｉ単
結晶を育成する引上げ装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulling apparatus for maintaining a constant oxygen concentration on the surface of a melt by controlling an atmosphere and growing a Si single crystal of stable quality.
【０００２】[0002]
【従来の技術】融液から単結晶を育成する代表的な方法
として、チョクラルスキー法がある。チョクラルスキー
方法では、図１に示すようにチャンバー１の内部に配置
したルツボ２を、回転及び昇降可能にサポート３で支持
する。ルツボ２の外周には、ヒータ４及び保温材５が同
心円状に設けられ、ルツボ２に収容した原料をヒータ４
で集中的に加熱し、融液６を調製する。融液６は、単結
晶成長に好適な温度に維持される。融液６に種結晶７を
接触させ、種結晶７の結晶方位を倣った単結晶８を成長
させる。種結晶７は、ワイヤ９を介して回転巻取り機構
１０から吊り下げられ、単結晶８の成長に応じて回転し
ながら引上げられる。また、ルツボ２も、サポート３を
介して適宜回転しながら下降する。サポート３の降下速
度，回転速度及び種結晶７の回転速度，上昇速度等は、
融液６から引上げられる単結晶８の成長速度に応じて制
御される。2. Description of the Related Art The Czochralski method is a typical method for growing a single crystal from a melt. In the Czochralski method, as shown in FIG. 1, a crucible 2 arranged inside a chamber 1 is supported by a support 3 so as to be rotatable and vertically movable. A heater 4 and a heat insulating material 5 are concentrically provided on the outer periphery of the crucible 2, and the raw material contained in the crucible 2 is heated by the heater 4
Is intensively heated to prepare a melt 6. The melt 6 is maintained at a temperature suitable for single crystal growth. The seed crystal 7 is brought into contact with the melt 6 to grow a single crystal 8 that follows the crystal orientation of the seed crystal 7. The seed crystal 7 is hung from the rotary winding mechanism 10 via a wire 9 and pulled up while rotating according to the growth of the single crystal 8. The crucible 2 also descends while rotating appropriately via the support 3. The descending speed and the rotating speed of the support 3 and the rotating speed and the ascending speed of the seed crystal 7 are
It is controlled according to the growth rate of the single crystal 8 pulled up from the melt 6.
【０００３】Ｓｂをｎ型不純物として添加した融液６を
使用して引き上げを行うと、得られた単結晶８にＳｂが
導入され、高伝導度の半導体材料が得られる。また、融
液６にルツボ２から溶出したＳｉＯ2 に起因する酸素が
導入されており、その酸素も単結晶８に取り込まれる。
単結晶８に含まれる酸素は、単結晶８が熱処理されると
きバルク中に析出し、析出欠陥となる。この析出欠陥
は、電子デバイスを構成する半導体単結晶基板の表面に
残存する重金属不純物を捕捉して無害化するゲッタリン
グ中心として利用される。また、固溶している酸素は、
半導体単結晶基板の強度を向上させる作用も呈する。こ
のようなことから、融液の酸素濃度を高くすると、単結
晶中に取り込まれる酸素濃度を増大させる上で、融液の
酸素濃度を高く維持することが望まれる。しかし、従来
の方法においては、Ｓｉ融液の酸素濃度を高レベルに安
定維持することは困難であった。本発明者等は、Ｓｉ融
液の物性を調査・研究する過程で、多量にＳｂドープし
たＳｉ融液を使用するとき、Ｓｂ含有量の上昇に伴って
Ｓｉ融液の酸素濃度が一義的に上昇することを見い出し
た。そして、特願平５−６９９２４号で、このＳｂ含有
量と酸素濃度との関係を利用し、融液のＳｂ含有量から
酸素濃度を算出する方法を提案した。When the melt 6 added with Sb as an n-type impurity is used for pulling, Sb is introduced into the obtained single crystal 8 to obtain a semiconductor material having high conductivity. Further, oxygen derived from SiO 2 eluted from the crucible 2 is introduced into the melt 6, and the oxygen is also taken into the single crystal 8.
Oxygen contained in the single crystal 8 precipitates in the bulk when the single crystal 8 is heat-treated and becomes a precipitation defect. This precipitation defect is used as a gettering center for capturing and detoxifying the heavy metal impurities remaining on the surface of the semiconductor single crystal substrate constituting the electronic device. Also, the solid solution oxygen is
It also acts to improve the strength of the semiconductor single crystal substrate. Therefore, when the oxygen concentration of the melt is increased, it is desired to maintain the oxygen concentration of the melt high in order to increase the oxygen concentration taken into the single crystal. However, in the conventional method, it was difficult to stably maintain the oxygen concentration of the Si melt at a high level. In the process of investigating and studying the physical properties of the Si melt, the present inventors have found that when using a large amount of Sb-doped Si melt, the oxygen concentration of the Si melt is uniquely increased as the Sb content increases. I found out to rise. Then, Japanese Patent Application No. 5-69924 proposes a method of calculating the oxygen concentration from the Sb content of the melt by utilizing the relationship between the Sb content and the oxygen concentration.
【０００４】[0004]
【発明が解決しようとする課題】多量のＳｂを添加した
Ｓｉ融液では、Ｓｂ2 Ｏ，ＳｉＯ等として酸素が融液表
面から雰囲気中に放出され易くなる。この傾向は、Ｐ，
Ａｓ，Ｂｉ等の他のＶ族元素でドープしたＳｉ融液でも
同様にみられる。融液表面から酸素が放出されることに
より、融液中の酸素濃度が変動し、引き上げられている
Ｓｉ単結晶の酸素濃度を著しく低下させる。そのため、
Ｓｉ単結晶から切り出されたウエハやデバイス等に、所
定の特性を与えることができない。酸素濃度は、Ｓｉ単
結晶の引上げ中にも変動する。引上げ中の変動によりＳ
ｉ単結晶の酸素濃度が不安定になり、一定した品質の単
結晶が得られない。本発明は、このような問題を解消す
べく案出されたものであり、融液の上方にある雰囲気ガ
スの酸素分圧及び雰囲気圧から融液表面の酸素濃度を求
め、この酸素濃度が一定になるように雰囲気制御するこ
とにより、高レベルで酸素濃度が一定したＳｉ単結晶を
得ることを目的とする。In a Si melt added with a large amount of Sb, oxygen is easily released from the melt surface into the atmosphere as Sb 2 O, SiO and the like. This tendency is P,
The same applies to Si melts doped with other group V elements such as As and Bi. By releasing oxygen from the surface of the melt, the oxygen concentration in the melt fluctuates, and the oxygen concentration of the pulled Si single crystal is significantly reduced. for that reason,
Predetermined characteristics cannot be given to a wafer, device, etc. cut out from a Si single crystal. The oxygen concentration also fluctuates during pulling of the Si single crystal. S due to fluctuations during pulling
The oxygen concentration of the i single crystal becomes unstable, and a single crystal of constant quality cannot be obtained. The present invention has been devised to solve such a problem, and obtains the oxygen concentration on the surface of the melt from the oxygen partial pressure and the atmospheric pressure of the atmosphere gas above the melt, and this oxygen concentration is constant. The purpose is to obtain an Si single crystal in which the oxygen concentration is constant at a high level by controlling the atmosphere so that.
【０００５】[0005]
【課題を解決するための手段】本発明の単結晶引上げ装
置は、その目的を達成するため、ルツボに収容した融液
からＳｉ単結晶が引き上げられる単結晶育成領域を区画
するチャンバーと、該チャンバーとＡｒガス供給源とを
接続する給気管と、前記Ｓｉ融液の上方にある雰囲気の
酸素分圧を検出する検出器と、前記チャンバー内の雰囲
気圧を測定する圧力計と、前記検出器及び前記圧力計か
らの検出値に基づいて融液表面の酸素濃度を求め、目標
酸素濃度との差に相当する雰囲気圧を演算する制御系
と、前記給気管の途中に組み込まれ、前記雰囲気圧に対
応する制御信号が前記制御系から入力される流量調整弁
とを備えていることを特徴とする。In order to achieve the object, the apparatus for pulling a single crystal of the present invention has a chamber for defining a single crystal growth region in which a Si single crystal is pulled from a melt contained in a crucible, and the chamber. And an Ar gas supply source, a detector for detecting the oxygen partial pressure of the atmosphere above the Si melt, a pressure gauge for measuring the atmospheric pressure in the chamber, the detector, and Obtaining the oxygen concentration of the melt surface based on the detection value from the pressure gauge, a control system for calculating the atmospheric pressure corresponding to the difference with the target oxygen concentration, and incorporated in the middle of the air supply pipe, to the atmospheric pressure And a flow control valve to which a corresponding control signal is input from the control system.
【０００６】質量が異なるＨｅ，Ｎｅ，Ｋｒ，Ｘｅ等の
希ガスをＡｒ雰囲気に混合することによっても、融液表
面から酸化物として雰囲気中に放出される酸素量が変わ
る。したがって、Ａｒガスに混合される希ガスの種類や
配合割合によっても、融液表面の酸素濃度を制御でき
る。この場合、Ａｒガス供給用給気管の途中に開口さ
れ、Ａｒガス以外の希ガス供給源に接続された第２給気
管をＡｒガス供給用給気管の途中に開口し、第２給気管
の途中に組み込まれた流量調整弁に制御系からの制御信
号を入力する。そして、検出器及び圧力計からの検出値
に基づいて算出された融液表面の酸素濃度が目標酸素濃
度より高い場合にはＨｅ又はＮｅを、目標酸素濃度より
低い場合にはＫｒ又はＸｅを、希ガス供給源から第２給
気管を経てＡｒガス供給用給気管に送り込む。雰囲気制
御によって融液表面の酸素濃度が変わる融液としては、
比較的多量のＶ族元素でドープしたＳｉ融液が代表的な
ものである。しかし、他のドーパントを添加したＳｉ融
液やＧｅ融液等においても同様な傾向がみられる。以
下、Ｖ族元素としてＳｂでドープしたＳｉ融液を例にと
って、融液表面の酸素濃度と雰囲気との関係を説明す
る。By mixing rare gases such as He, Ne, Kr, and Xe having different masses into the Ar atmosphere, the amount of oxygen released from the surface of the melt as an oxide into the atmosphere is changed. Therefore, the oxygen concentration on the surface of the melt can be controlled also by the kind and mixing ratio of the rare gas mixed with the Ar gas. In this case, a second air supply pipe opened in the middle of the Ar gas supply air supply pipe and connected to a rare gas supply source other than Ar gas is opened in the middle of the Ar gas supply air supply pipe, and in the middle of the second air supply pipe. The control signal from the control system is input to the flow control valve incorporated in the. Then, when the oxygen concentration of the melt surface calculated based on the detection values from the detector and the pressure gauge is higher than the target oxygen concentration, He or Ne is used, and when the oxygen concentration is lower than the target oxygen concentration, Kr or Xe is used, The rare gas is supplied from the rare gas supply source to the Ar gas supply air supply pipe through the second air supply pipe. As the melt whose oxygen concentration on the surface of the melt changes depending on the atmosphere control,
A typical example is a Si melt doped with a relatively large amount of Group V element. However, the same tendency is observed in Si melt, Ge melt and the like to which other dopants are added. Hereinafter, the relationship between the oxygen concentration on the surface of the melt and the atmosphere will be described by taking the Si melt doped with Sb as the group V element as an example.
【０００７】[0007]
【作用】Ｓｉ融液から引き上げられる単結晶の酸素濃度
は、石英ルツボから融液に溶出する酸素や融液中の酸素
濃度に依存するものではなく、専ら融液表面の酸素濃度
が反映される。しかし、雰囲気ガスと接触する融液表面
は、酸化物として雰囲気ガスで持ち去られる酸素量が多
く、酸素濃度が一定しない。特に、蒸気圧が大きな酸化
物として酸素が放出されるＶ続元素でドープしたＳｉ融
液では、この傾向が強くなる。本発明者等は、雰囲気圧
や雰囲気ガスの組成に融液表面の酸素濃度が影響される
ことを見い出した。雰囲気圧は、次のようなメカニズム
で融液表面の酸素濃度に影響を与えているものと推察さ
れる。理想気体が充満されている雰囲気にＳｉ融液がお
かれ、このＳｉ融液から単結晶が引き上げられているも
のと仮定する。融液表面から蒸発する気体分子が雰囲気
のガス分子と衝突する回数ｆは、雰囲気の圧力Ｐとの間
にｆ∝Ｐ2 の関係をもっている。衝突回数ｆが大きくな
ると融液表面からの気体蒸発が抑えられ、融液表面から
放出される酸素量が減少する。The oxygen concentration of the single crystal pulled up from the Si melt does not depend on the oxygen dissolved in the melt from the quartz crucible or the oxygen concentration in the melt, but the oxygen concentration on the surface of the melt is exclusively reflected. . However, the surface of the melt that is in contact with the atmospheric gas has a large amount of oxygen carried away by the atmospheric gas as an oxide, and the oxygen concentration is not constant. In particular, this tendency becomes stronger in the Si melt doped with a V-series element that releases oxygen as an oxide having a large vapor pressure. The present inventors have found that the oxygen concentration on the melt surface is affected by the atmospheric pressure and the composition of the atmospheric gas. It is speculated that the atmospheric pressure affects the oxygen concentration on the melt surface by the following mechanism. It is assumed that the Si melt is placed in the atmosphere filled with the ideal gas and the single crystal is pulled from the Si melt. The number f of collisions of gas molecules evaporated from the melt surface with gas molecules of the atmosphere has a relationship of f∝P 2 with the pressure P of the atmosphere. When the number of collisions f increases, gas evaporation from the melt surface is suppressed, and the amount of oxygen released from the melt surface decreases.
【０００８】特に、Ｖ族元素でドープされているＳｉ融
液では、それぞれの元素単体及び酸化物が融液表面から
蒸発するが、１５００℃以下の温度域においてはこれら
蒸発物がＳｉＯに比較して高い蒸気圧を示すことから、
雰囲気圧による影響が大きく現れる。したがって、雰囲
気圧Ｐを大きくしたときには、酸素の放出が抑制され、
融液表面が高酸素濃度に維持される。この融液から育成
されたＳｉ単結晶は、高酸素濃度の単結晶になる。逆
に、雰囲気圧Ｐを小さくすると、酸素の放出が促進さ
れ、低酸素濃度のＳｉ単結晶が得られる。雰囲気ガスの
組成は、次のようなメカニズムで融液表面の酸素濃度に
影響を与えているものと推察される。Particularly, in the Si melt doped with the group V element, the elemental element and the oxide evaporate from the surface of the melt, but in the temperature range of 1500 ° C. or less, these evaporates are compared with SiO. Shows high vapor pressure,
The influence of the atmospheric pressure appears significantly. Therefore, when the atmospheric pressure P is increased, the release of oxygen is suppressed,
The melt surface is maintained at a high oxygen concentration. The Si single crystal grown from this melt becomes a high oxygen concentration single crystal. On the contrary, when the atmospheric pressure P is reduced, the release of oxygen is promoted and a Si single crystal having a low oxygen concentration can be obtained. It is assumed that the composition of the atmospheric gas affects the oxygen concentration on the surface of the melt by the following mechanism.
【０００９】理想気体が充満されている雰囲気にＳｉ融
液がおかれ、このＳｉ融液から単結晶が引き上げられて
いるものと仮定する。Ｓｉ融液の表面から蒸発する気体
分子が雰囲気のガス分子と衝突する回数ｆは、雰囲気ガ
スの質量ｍg の平方根に反比例する。衝突エネルギーＥ
は、質量ｍg との間にＥ＝Ｋ×ｍg （Ｋ：定数）の関係
をもっている。したがって、蒸発する気体分子と雰囲気
ガスとの衝突は、質量ｍg の平方根に比例する。このこ
とから、単結晶の引上げに通常使用されているＡｒより
も質量が大きな希ガスを使用すると、融液表面から気体
の蒸発が抑えられ、酸化物の蒸発量が少なくなり、融液
表面の酸素濃度、ひいては得られたＳｉ単結晶の酸素濃
度が高レベルに維持されることが予想される。逆に、Ａ
ｒよりも質量が小さい希ガスを使用すると、酸素濃度が
低いＳｉ単結晶が得られることが予想される。希ガスの
質量が酸素濃度に与える影響は、単結晶引き上げに通常
使用されているＡｒガスに希ガスを配合した場合でも同
様に維持される。この雰囲気ガスの組成が融液表面の酸
素濃度に与える影響は、蒸発速度が大きなＳｂ2 Ｏとし
て酸素が放出されるＳｂドープＳｉ融液で顕著に現れ
る。It is assumed that the Si melt is placed in an atmosphere filled with the ideal gas, and the single crystal is pulled from the Si melt. The number f of collisions of the gas molecules evaporated from the surface of the Si melt with the gas molecules of the atmosphere is inversely proportional to the square root of the mass m g of the atmosphere gas. Collision energy E
Has a relationship of E = K × m g (K: constant) with mass m g . Therefore, the collision between the vaporized gas molecules and the atmospheric gas is proportional to the square root of the mass mg . From this, when a rare gas having a larger mass than Ar, which is usually used for pulling a single crystal, is used, evaporation of the gas from the melt surface is suppressed, and the evaporation amount of the oxide is reduced. It is expected that the oxygen concentration, and thus the oxygen concentration of the obtained Si single crystal, will be maintained at a high level. Conversely, A
It is expected that a Si single crystal having a low oxygen concentration can be obtained by using a rare gas having a mass smaller than r. The influence of the mass of the rare gas on the oxygen concentration is maintained even when Ar gas that is usually used for pulling a single crystal is mixed with the rare gas. The influence of the composition of the atmosphere gas on the oxygen concentration on the surface of the melt is remarkable in the Sb-doped Si melt in which oxygen is released as Sb 2 O having a high evaporation rate.
【００１０】したがって、目標酸素濃度に対応する雰囲
気圧や雰囲気ガス組成を予め求めておき、引上げ中に測
定した雰囲気圧，酸素濃度等に基づき、目標酸素濃度に
近付くように条件設定すると、融液表面の酸素濃度が一
定に維持される。その結果、育成されたＳｉ単結晶は、
一定した酸素濃度をもち、品質安定性に優れたものとな
る。育成条件の制御は、たとえば図２に示す設備構成の
引上げ装置を使用する。ルツボ２は、単結晶８が引き上
げられる融液６を収容し、チャンバー１にセットされて
いる。チャンバー１には、チャンバー１内を所定の減圧
雰囲気に維持するための吸引ポンプ１２が接続されてい
る。真空チャンバー１から吸引ポンプ１２に至る排気系
に圧力計１３が設けられており、圧力計１３によって真
空チャンバー１内の圧力が測定される。雰囲気中の酸素
分圧を測定する検出器としての酸素センサー１４は、融
液６の液面近傍に検出端子を臨ませている。Therefore, if the atmospheric pressure and the atmospheric gas composition corresponding to the target oxygen concentration are obtained in advance and the conditions are set so as to approach the target oxygen concentration based on the atmospheric pressure, the oxygen concentration, etc. measured during pulling, the melt will be melted. The oxygen concentration on the surface is kept constant. As a result, the grown Si single crystal is
It has a constant oxygen concentration and is excellent in quality stability. To control the growing conditions, for example, a pulling device having the equipment configuration shown in FIG. 2 is used. The crucible 2 contains the melt 6 from which the single crystal 8 is pulled up, and is set in the chamber 1. A suction pump 12 for maintaining the inside of the chamber 1 in a predetermined reduced pressure atmosphere is connected to the chamber 1. A pressure gauge 13 is provided in the exhaust system from the vacuum chamber 1 to the suction pump 12, and the pressure inside the vacuum chamber 1 is measured by the pressure gauge 13. The oxygen sensor 14 as a detector for measuring the oxygen partial pressure in the atmosphere has a detection terminal in the vicinity of the liquid surface of the melt 6.
【００１１】酸素センサー１４で検出された酸素分圧
は、圧力計１３で測定された雰囲気圧と共に制御系１５
に入力される。結晶成長中における石英ルツボの溶解か
ら結晶への混入及び雰囲気への蒸発の全経路にわたって
酸素の移動が平衡状態であると仮定すると、Ｓｉ融液表
面の酸素濃度Ｃ2 は、拡散層理論に基づき式Ｃ2 ＝Ｃ1
−Ｃevで表される。ここで、Ｃ1 は融液自体の酸素濃度
を、Ｃevは融液表面から蒸発する酸素濃度を示す。理想
基体では、酸素センサー１４で測定した酸素分圧ＰO と
蒸発酸素濃度Ｃevとの間に正比例の関係があるため、Ｃ
ev＝ｋ・ＰO の関係式が成立する。ここで、ｋは、
（１．０〜９．０）×１０16トール・原子数／ｃｍ3 の
定数である。また、融液表面の酸素濃度Ｃ2 も雰囲気圧
Ｐとの間に次式の関係をもつことを解明した。The oxygen partial pressure detected by the oxygen sensor 14 is controlled by the control system 15 together with the atmospheric pressure measured by the pressure gauge 13.
Entered in. Assuming that the movement of oxygen is in an equilibrium state over the entire course of melting of the quartz crucible into the crystal during crystal growth and evaporation into the atmosphere, the oxygen concentration C 2 on the surface of the Si melt is based on the diffusion layer theory. Formula C 2 = C 1
-Represented by C ev . Here, C 1 represents the oxygen concentration of the melt itself, and C ev represents the oxygen concentration evaporated from the surface of the melt. In an ideal substrate, since there is a direct proportional relationship between the oxygen partial pressure P O measured by the oxygen sensor 14 and the vaporized oxygen concentration C ev , C
The relational expression of ev = k · P O holds. Where k is
The constant is (1.0 to 9.0) × 10 16 torr · atom number / cm 3 . It was also clarified that the oxygen concentration C 2 on the melt surface also has the following relationship with the atmospheric pressure P.
【００１２】[0012]
【数１】 [Equation 1]
【００１３】ただし、Ｋは雰囲気ガスの種類及びドーピ
ング量で定まる定数であり、ドーピング量が１．０×１
０-4原子％以上のとき、Ｎｅでは１．００〜１．２４，
Ａｒでは０．８５〜１．０５，Ｋｒでは０．６４〜０．
８０，Ｘｅでは０．４２〜０．５９，Ｒｎでは０．３０
〜０．３８の範囲にある。なお、酸素濃度は、ＪＥＩＤ
Ａ換算値（３．０３）を使用する。したがって、表面酸
素濃度Ｃ2 は、酸素分圧ＰO 及び雰囲気圧Ｐを変数とし
て式（１）で表すことができる。However, K is a constant determined by the type of atmospheric gas and the doping amount, and the doping amount is 1.0 × 1.
When it is 0 -4 atomic% or more, Ne is 1.00 to 1.24.
0.85 to 1.05 for Ar and 0.64 to 0.5 for Kr.
80, Xe 0.42-0.59, Rn 0.30
Is in the range of to 0.38. The oxygen concentration is JEID
The A conversion value (3.03) is used. Therefore, the surface oxygen concentration C 2 can be expressed by the equation (1) with the oxygen partial pressure P O and the atmospheric pressure P as variables.
【００１４】[0014]
【数２】 [Equation 2]
【００１５】制御系１５では、このようにして酸素分圧
ＰO 及び雰囲気圧Ｐから単結晶引上げ中の融液表面の酸
素濃度を演算する。演算値は、制御系１５に予め入力さ
れている目標酸素濃度を比較される。演算値と目標酸素
濃度との差は、制御系１５で雰囲気圧及び必要に応じて
ガス組成に変換され、それぞれ制御信号として吸引ポン
プ１２及び流量調整弁１６，１７に出力される。流量調
整弁１６は、Ａｒガス供給源１８とチャンバー１とを接
続する給気管１９の途中に組み込まれており、チャンバ
ー１に送り込まれるＡｒガスの流量を調整する。流量調
整弁１７は、希ガス供給源２０から延びている第２給気
管２１に設けられている。第２給気管２１は、先端が給
気管１９に開口している。制御系１５から入力された制
御信号によって吸引ポンプ１２の回転数及び流量調整弁
１６の開度が制御され、チャンバー１内が目標酸素濃度
に対応した雰囲気圧に維持される。また、雰囲気ガスの
組成を変更する場合には、制御系１５からの制御信号に
より流量調整弁１７の開度を調整し、Ｈｅ，Ｎｅ，Ｋ
ｒ，Ｘｅ等の質量がＡｒと異なる希ガスをチャンバー１
に送り込む。The control system 15 thus calculates the oxygen concentration on the surface of the melt during pulling of the single crystal from the oxygen partial pressure P O and the atmospheric pressure P. The calculated value is compared with the target oxygen concentration which is previously input to the control system 15. The difference between the calculated value and the target oxygen concentration is converted into the atmospheric pressure and the gas composition as necessary by the control system 15, and is output to the suction pump 12 and the flow rate adjusting valves 16 and 17 as control signals, respectively. The flow rate adjusting valve 16 is incorporated in the middle of the air supply pipe 19 that connects the Ar gas supply source 18 and the chamber 1, and adjusts the flow rate of the Ar gas sent into the chamber 1. The flow rate adjusting valve 17 is provided in the second air supply pipe 21 extending from the rare gas supply source 20. The tip of the second air supply pipe 21 is open to the air supply pipe 19. The rotation speed of the suction pump 12 and the opening degree of the flow rate adjusting valve 16 are controlled by the control signal input from the control system 15, and the inside of the chamber 1 is maintained at the atmospheric pressure corresponding to the target oxygen concentration. Further, when changing the composition of the atmospheric gas, the opening degree of the flow rate adjusting valve 17 is adjusted by the control signal from the control system 15, and He, Ne, K
Noble gas whose mass is different from Ar, such as r and Xe
Send to.
【００１６】雰囲気圧及び雰囲気ガス組成は、単結晶引
上げ中の条件に基づきオンラインで制御される。その結
果、融液表面の酸素濃度が高精度で目標値に維持され、
酸素濃度が一定したＳｉ単結晶が育成される。また、雰
囲気圧及び雰囲気ガス組成の変更によって、３×１０17
〜１．５×１０18個／ｃｍ3 の広範囲でＳｉ単結晶の酸
素濃度が調整される。特に、ＳｂドープＳｉ融液から引
き上げられた単結晶では、高レベルで酸素濃度が安定化
する。酸素濃度が高いＳｉ単結晶は、Ｖ族元素をドーパ
ントとして含んでいることから、リーク電流が少なく、
重金属類を効率よくゲッタリングできる等の特性をもっ
た半導体材料として使用される。しかも、酸素濃度が所
定範囲に調整されているので、品質に関する信頼性が高
いものとなる。この傾向は、ドーパントとして、Ｐ，Ａ
ｓ，Ｂｉ等の他のＶ族元素を使用する場合も同様であ
る。The atmospheric pressure and the atmospheric gas composition are controlled online on the basis of the conditions during the pulling of the single crystal. As a result, the oxygen concentration on the melt surface is maintained at the target value with high accuracy,
A Si single crystal having a constant oxygen concentration is grown. Also, by changing the atmospheric pressure and the composition of the atmospheric gas, 3 × 10 17
The oxygen concentration of the Si single crystal is adjusted in a wide range of up to 1.5 × 10 18 pieces / cm 3 . Particularly, in the single crystal pulled from the Sb-doped Si melt, the oxygen concentration is stabilized at a high level. Since the Si single crystal having a high oxygen concentration contains a group V element as a dopant, it has a small leak current,
It is used as a semiconductor material having properties such as efficient gettering of heavy metals. Moreover, since the oxygen concentration is adjusted within a predetermined range, the reliability regarding quality becomes high. This tendency shows that P, A
The same applies when other group V elements such as s and Bi are used.
【００１７】[0017]
実施例１：純Ｓｉ２０ｇを直径５０ｍｍ及び高さ６０ｍ
ｍのルツボに入れ、垂直方向の温度差５０℃をつけて表
面温度１４５０℃に加熱した。この状態で３０分間保持
した後、０．７ｇの純ＳｂをＳｉ融液に添加した。更に
同じ温度条件下で３０分間保持し、冷却速度２００℃／
時で１３５０℃まで冷却し、冷却速度５０℃／時で室温
まで冷却した。このようにして、目標Ｓｂ濃度０．８原
子％のＳｂドープＳｉ融液を用意した。Ａｒ雰囲気中で
ＳｂドープＳｉ融液を１４２６〜１５４２℃に加熱し、
９０分間保持した後、単結晶引上げを開始した。得られ
た単結晶から厚さ２ｍｍの試験片を切り出し、ＳＩＭＳ
法で酸素濃度を測定した。引上げ中に、融液表面の酸素
濃度を検出し、同一引上げ条件下で融液自体の酸素濃度
を測定した。Example 1: 20 g of pure Si having a diameter of 50 mm and a height of 60 m
The sample was placed in a crucible of m and heated to a surface temperature of 1450 ° C with a vertical temperature difference of 50 ° C. After holding in this state for 30 minutes, 0.7 g of pure Sb was added to the Si melt. Further, the same temperature condition is maintained for 30 minutes, and the cooling rate is 200 ° C
The temperature was cooled down to 1350 ° C., and the cooling rate was cooled down to room temperature at 50 ° C./hour. In this way, an Sb-doped Si melt having a target Sb concentration of 0.8 atomic% was prepared. Heating the Sb-doped Si melt to 1426 to 1542 ° C. in an Ar atmosphere,
After holding for 90 minutes, single crystal pulling was started. A 2 mm-thick test piece was cut out from the obtained single crystal and SIMS
The oxygen concentration was measured by the method. During the pulling, the oxygen concentration on the surface of the melt was detected, and the oxygen concentration of the melt itself was measured under the same pulling conditions.
【００１８】引き上げられたＳｉ単結晶から切り出され
た試験片の酸素濃度を、Ｓｉ融液自体及び融液表面の酸
素濃度との関係で表１に示す。表１から、Ｓｉ単結晶の
酸素濃度は、融液自体の酸素濃度に依存せず、融液表面
の酸素濃度に応じて変わっていることが判る。表１にお
ける融液自体の酸素濃度は、急冷凝固した融液につい
て、単結晶の試験片と同様にＳＩＭＳ法でで測定した。
融液表面の酸素濃度は、酸素センサー１４からの検出値
に基づき、前掲した式（１）に従って算出した。The oxygen concentration of the test piece cut out from the pulled Si single crystal is shown in Table 1 in relation to the oxygen concentration on the Si melt itself and on the melt surface. From Table 1, it can be seen that the oxygen concentration of the Si single crystal does not depend on the oxygen concentration of the melt itself, but changes depending on the oxygen concentration on the surface of the melt. The oxygen concentration of the melt itself in Table 1 was measured by the SIMS method for the melt that was rapidly solidified, as with the single crystal test piece.
The oxygen concentration on the surface of the melt was calculated according to the above-mentioned formula (1) based on the value detected by the oxygen sensor 14.
【００１９】[0019]
【表１】 [Table 1]
【００２０】また、定常状態でＳｉ単結晶が引き上げら
れているとき、チャンバー１内の雰囲気圧を変動させ、
融液表面の酸素濃度に与える雰囲気圧の影響を調査し
た。調査結果を示す表２から明らかなように、低い雰囲
気圧では酸化物の蒸発が活発になるため融液表面の酸素
濃度が低下し、雰囲気圧が大きくなるに従って酸素濃度
が上昇していた。When the Si single crystal is pulled in a steady state, the atmospheric pressure in the chamber 1 is changed,
The effect of atmospheric pressure on the oxygen concentration on the melt surface was investigated. As is clear from Table 2 showing the investigation results, the oxide concentration on the surface of the melt was lowered due to the active evaporation of oxides at a low atmospheric pressure, and the oxygen concentration was increased as the atmospheric pressure was increased.
【００２１】[0021]
【表２】 [Table 2]
【００２２】そこで、表１及び表２のデータを予め制御
系１５に入力しておき、これらデータと比較しながら単
結晶引上げ中の雰囲気を制御した。融液表面の目標酸素
濃度を４．０×１０17原子数／ｃｍ3 に設定し、この目
標酸素濃度と制御系１５で算出された酸素濃度とのズレ
に応じて、チャンバー１内の雰囲気圧を１０〜５０トー
ルの間で変動させた。その結果、得られたＳｉ単結晶の
酸素濃度は、７．０×１０17原子数／ｃｍ3 を中心とし
て±０．２×１０17原子数／ｃｍ3 の狭い範囲に収まっ
ていた。Therefore, the data shown in Tables 1 and 2 were input to the control system 15 in advance, and the atmosphere during the pulling of the single crystal was controlled by comparing with these data. The target oxygen concentration on the surface of the melt was set to 4.0 × 10 17 atoms / cm 3 , and the atmospheric pressure in the chamber 1 was adjusted according to the difference between the target oxygen concentration and the oxygen concentration calculated by the control system 15. Fluctuated between 10 and 50 Torr. As a result, the oxygen concentration of the obtained Si single crystal was within a narrow range of ± 0.2 × 10 17 atoms / cm 3 centered on 7.0 × 10 17 atoms / cm 3 .
【００２３】実施例２：実施例１と同様な条件下で、Ａ
ｒガスに対するＨｅ，Ｎｅ，Ｋｒ及びＸｅの配合割合が
融液表面の酸素濃度に与える影響を調査した。その結
果、表３に示すように、質量が小さいＨｅ又はＮｅを混
合した場合には酸素濃度が低下し、質量が大きいＫｒ又
はＸｅを混合した場合には酸素濃度が上昇した。また、
酸素濃度の変化率は、それぞれの希ガス配合割合と密接
な相関関係を持っていた。Example 2: Under the same conditions as in Example 1, A
The influence of the mixing ratio of He, Ne, Kr and Xe to the r gas on the oxygen concentration on the melt surface was investigated. As a result, as shown in Table 3, the oxygen concentration decreased when He or Ne having a small mass was mixed, and the oxygen concentration increased when Kr or Xe having a large mass was mixed. Also,
The rate of change of oxygen concentration had a close correlation with the blending ratio of each noble gas.
【００２４】[0024]
【表３】 [Table 3]
【００２５】表３のデータを、表１及び表２のデータと
共に予め制御系１５に入力しておき、単結晶引上げ中に
算出された融液表面の酸素濃度に応じて、雰囲気圧を１
０〜３０トールの範囲で変えると共に、Ｈｅの配合割合
を０〜３０体積％の範囲で変動させた。得られたＳｉ単
結晶の酸素濃度は、目標酸素濃度９．０×１０17原子数
／ｃｍ3 を中心として±０．２××１０17原子数／ｃｍ
3 の狭い範囲に収まっていた。また、雰囲気圧を１０〜
３０トールの範囲で変えると共に、Ｋｒの配合割合を０
〜４０体積％の範囲で変動させた。得られたＳｉ単結晶
の酸素濃度は、目標酸素濃度６．０×１０17原子数／ｃ
ｍ3 を中心として±０．３×１０17原子数／ｃｍ3 の狭
い範囲に収まっていた。このことから、雰囲気圧及び必
要に応じて雰囲気ガス組成を変えることにより、高レベ
ルで酸素濃度が安定したＳｉ単結晶が育成されることが
判る。この制御によって、Ｓｉ単結晶の酸素濃度は、
３．０×１０17〜１．５×１０18個／ｃｍ3 の広範囲で
調整される。The data in Table 3 are input to the control system 15 in advance together with the data in Tables 1 and 2, and the atmospheric pressure is set to 1 in accordance with the oxygen concentration on the surface of the melt calculated during the pulling of the single crystal.
While changing in the range of 0 to 30 Torr, the blending ratio of He was changed in the range of 0 to 30% by volume. The oxygen concentration of the obtained Si single crystal was ± 0.2 ×× 10 17 atoms / cm 3 around the target oxygen concentration of 9.0 × 10 17 atoms / cm 3.
It was within the narrow range of 3 . Also, the atmospheric pressure is 10 to
Change within the range of 30 Torr and change the Kr compounding ratio to 0.
Varyed in the range of -40% by volume. The oxygen concentration of the obtained Si single crystal was 6.0 × 10 17 atoms / c.
It was within a narrow range of ± 0.3 × 10 17 atoms / cm 3 centered on m 3 . From this, it is understood that by changing the atmospheric pressure and the atmospheric gas composition as necessary, a Si single crystal with a high oxygen concentration and a stable oxygen concentration can be grown. By this control, the oxygen concentration of the Si single crystal is
It is adjusted in a wide range of 3.0 × 10 17 to 1.5 × 10 18 pieces / cm 3 .
【００２６】[0026]
【発明の効果】 以上に説明したように、本発明の引上
げ装置は、融液表面の酸素濃度に応じて雰囲気圧を制御
する機構及び必要に応じてＡｒ雰囲気に混合される希ガ
スの配合割合を制御する機構を備えている。そして、単
結晶引上げ中に融液表面の酸素濃度が変動した場合、設
定値からのズレが少なくなるように雰囲気圧や雰囲気ガ
ス組成を調整している。これにより、高レベルで酸素濃
度が安定したＳｉ単結晶が育成される。得られた単結晶
は、半導体デバイスの動作中にリークした電子のトラッ
プや重金属類のゲッタリング等に有効な酸素を多量に含
んでいることから、リーク電流に対して敏感なパワー用
デバイスや基板内のチャンネルを利用したバイポーラデ
バイス等に適した半導体材料として使用される。As described above, in the pulling apparatus of the present invention, the mechanism for controlling the atmospheric pressure according to the oxygen concentration on the surface of the melt and the mixing ratio of the noble gas mixed in the Ar atmosphere as necessary. It is equipped with a mechanism for controlling. When the oxygen concentration on the surface of the melt fluctuates during pulling of the single crystal, the atmospheric pressure and the atmospheric gas composition are adjusted so that the deviation from the set value is reduced. As a result, a Si single crystal with a high level and stable oxygen concentration is grown. The obtained single crystal contains a large amount of oxygen, which is effective for trapping electrons leaked during the operation of semiconductor devices and gettering of heavy metals, so that power devices and substrates sensitive to leakage current It is used as a semiconductor material suitable for bipolar devices using the internal channels.
【図１】 融液から単結晶を引き上げるチョクラルスキ
ー法FIG. 1 Czochralski method for pulling a single crystal from a melt
【図２】 本発明に従った単結晶引上げ装置FIG. 2 Single crystal pulling apparatus according to the present invention
１：密閉容器 ２：ルツボ ３：サポート ４：
ヒータ ５：保温材 ６：融液 ７：種結晶 ８：
単結晶 ９：ワイヤ １０：回転巻取り機構 １
２：吸引ポンプ １３：圧力計 １４：酸素センサー １
５：制御系 １６，１７：流量調整弁 １８：Ａｒガス供給源 １９：Ａｒガスの給気管 ２０：Ａｒ以外の希ガ
ス供給源 ２１：希ガスの給気管1: Airtight container 2: Crucible 3: Support 4:
Heater 5: Heat insulating material 6: Melt 7: Seed crystal 8:
Single crystal 9: Wire 10: Rotating winding mechanism 1
2: Suction pump 13: Pressure gauge 14: Oxygen sensor 1
5: Control system 16 and 17: Flow control valve 18: Ar gas supply source 19: Ar gas supply pipe 20: Rare gas supply source other than Ar 21: Rare gas supply pipe
───────────────────────────────────────────────────── フロントページの続き (72)発明者 黄 新明 茨城県つくば市東光台１−16−２スカイハ イツＣ−101 (72)発明者 寺嶋 一高 神奈川県海老名市中野206−３ (72)発明者 木村 茂行 茨城県つくば市竹園３−712 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Huang Shinmei 1-16-2 Tokodai, Tsukuba City, Ibaraki Prefecture Sky Heights C-101 (72) Inventor Kazutaka Terashima 206-3 Nakano, Ebina City, Kanagawa Prefecture (72) Inventor Shigeyuki Kimura 3-712 Takezono, Tsukuba City, Ibaraki Prefecture
Claims (2)
引き上げられる単結晶育成領域を区画するチャンバー
と、該チャンバーとＡｒガス供給源とを接続する給気管
と、前記Ｓｉ融液の上方にある雰囲気の酸素分圧を検出
する検出器と、前記チャンバー内の雰囲気圧を測定する
圧力計と、前記検出器及び前記圧力計からの検出値に基
づいて融液表面の酸素濃度を求め、目標酸素濃度との差
に相当する雰囲気圧を演算する制御系と、前記給気管の
途中に組み込まれ、前記雰囲気圧に対応する制御信号が
前記制御系から入力される流量調整弁とを備えているＳ
ｉ単結晶の引上げ装置。1. A chamber for defining a single crystal growth region in which a Si single crystal is pulled from a melt contained in a crucible, an air supply pipe connecting the chamber and an Ar gas supply source, and a chamber above the Si melt. A detector that detects the oxygen partial pressure of a certain atmosphere, a pressure gauge that measures the atmospheric pressure in the chamber, and obtain the oxygen concentration on the melt surface based on the detection values from the detector and the pressure gauge, and the target. A control system for calculating an atmospheric pressure corresponding to a difference from the oxygen concentration, and a flow rate control valve incorporated in the air supply pipe and having a control signal corresponding to the atmospheric pressure input from the control system are provided. S
i Single crystal pulling device.
れ、Ａｒガス以外の希ガス供給源に接続された第２給気
管と、該第２給気管の途中に組み込まれ、制御系からの
制御信号が入力される流量調整弁とを備え、検出器及び
圧力計の検出値に基づいて算出された融液表面の酸素濃
度が目標酸素濃度より高い場合にはＨｅ又はＮｅを、目
標酸素濃度より低い場合にはＫｒ又はＸｅを、前記希ガ
ス供給源から前記第２給気管を経て前記Ａｒガス供給用
給気管に送り込む請求項１記載の引上げ装置。2. A second air supply pipe opened in the middle of the Ar gas supply air supply pipe and connected to a rare gas supply source other than Ar gas, and a second air supply pipe incorporated in the middle of the second air supply pipe, If the oxygen concentration on the melt surface calculated based on the detection values of the detector and the pressure gauge is higher than the target oxygen concentration, He or Ne is set as the target oxygen concentration. The pulling device according to claim 1, wherein when it is lower, Kr or Xe is sent from the rare gas supply source to the Ar gas supply air supply pipe through the second air supply pipe.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5335358A JP2760940B2 (en) | 1993-12-28 | 1993-12-28 | Si single crystal pulling device that adjusts oxygen concentration by controlling atmosphere |
| EP94104297A EP0625595B1 (en) | 1993-03-29 | 1994-03-18 | Control of oxygen concentration in single crystal pulled up from melt containing group-V element |
| DE69428302T DE69428302T2 (en) | 1993-03-29 | 1994-03-18 | Regulation of the oxygen concentration in a single crystal drawn from a melt containing a Group V element. |
| US08/291,833 US5524574A (en) | 1993-03-29 | 1994-08-17 | Control of oxygen concentration in single crystal pulled up from melt containing Group-V element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5335358A JP2760940B2 (en) | 1993-12-28 | 1993-12-28 | Si single crystal pulling device that adjusts oxygen concentration by controlling atmosphere |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07187889A true JPH07187889A (en) | 1995-07-25 |
| JP2760940B2 JP2760940B2 (en) | 1998-06-04 |
Family
ID=18287640
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5335358A Expired - Fee Related JP2760940B2 (en) | 1993-03-29 | 1993-12-28 | Si single crystal pulling device that adjusts oxygen concentration by controlling atmosphere |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2760940B2 (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01313398A (en) * | 1988-06-14 | 1989-12-18 | Furukawa Electric Co Ltd:The | Production of gaas compound semiconductor single crystal |
-
1993
- 1993-12-28 JP JP5335358A patent/JP2760940B2/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01313398A (en) * | 1988-06-14 | 1989-12-18 | Furukawa Electric Co Ltd:The | Production of gaas compound semiconductor single crystal |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2760940B2 (en) | 1998-06-04 |
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