JPH0329755B2 - - Google Patents
Info
- Publication number
- JPH0329755B2 JPH0329755B2 JP18577283A JP18577283A JPH0329755B2 JP H0329755 B2 JPH0329755 B2 JP H0329755B2 JP 18577283 A JP18577283 A JP 18577283A JP 18577283 A JP18577283 A JP 18577283A JP H0329755 B2 JPH0329755 B2 JP H0329755B2
- Authority
- JP
- Japan
- Prior art keywords
- cap
- crucible
- pulling
- single crystal
- melt
- 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.)
- Expired
Links
- 239000013078 crystal Substances 0.000 claims description 34
- 238000000034 method Methods 0.000 claims description 32
- 239000000470 constituent Substances 0.000 claims description 19
- 150000001875 compounds Chemical class 0.000 claims description 10
- 239000004065 semiconductor Substances 0.000 claims description 9
- 238000007789 sealing Methods 0.000 claims description 3
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 17
- 239000002994 raw material Substances 0.000 description 11
- 239000007789 gas Substances 0.000 description 9
- 239000000155 melt Substances 0.000 description 7
- 230000008020 evaporation Effects 0.000 description 5
- 238000001704 evaporation Methods 0.000 description 5
- 235000012431 wafers Nutrition 0.000 description 5
- 239000000203 mixture Substances 0.000 description 4
- -1 ZnS Chemical class 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 239000010453 quartz Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 230000005669 field effect Effects 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 229910005540 GaP Inorganic materials 0.000 description 1
- 229910000673 Indium arsenide Inorganic materials 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000002513 implantation Methods 0.000 description 1
- RPQDHPTXJYYUPQ-UHFFFAOYSA-N indium arsenide Chemical compound [In]#[As] RPQDHPTXJYYUPQ-UHFFFAOYSA-N 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
- C30B15/10—Crucibles or containers for supporting the melt
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
Description
（技術分野）
本発明は、蒸気圧の高い構成元素（以下、揮発
性構成元素と称す）を有する化合物半導体をチヨ
クラルスキー法（以下、CZ法と称す）により引
上げる方法に関するものである。
（背景技術）
例えばGaAs等のように、揮発性構成元素とし
てAs等を持つた化合物半導体単結晶をCZ法によ
り引上げるには第１図イ，ロに例を示すような方
法が採られていた。図において、るつぼ１は主ヒ
ーター２により加熱され、その中に原料融液３が
収容されている。引上軸４の下端にはシード（種
結晶）５が取付けられ、シード５を原料融液３表
面に浸漬し、なじませた後、種結晶５を回転させ
ながら引上げ、単結晶６を育成する。
この場合原料融液３中の揮発性構成元素（As
等）の蒸発を阻止し、融液３の組織を化学量論的
組成に保つため、イ図に示すように原料融液表面
をB2O3融液７でおおい、系全体を高圧のN2ガス
雰囲気下におくか、又はロ図に示すように引上部
を揮発性構成元素（As等）圧雰囲気の容器８に
収容し、可動部をB2O3融液９でシールし、シー
ル部をそれぞれ補助ヒーター１０で加熱するかし
ていた。
しかしイ図に示す方法では、高温のB2O3融液
７を通つてAs等が拡散するため、原料融液３か
らの揮発性構成元素の蒸発抜けを完全に抑えるこ
とができず、又高圧のN2ガスを雰囲気に用いる
ため、熱による対流が激しく、B2O3融液７を出
た単結晶６は急に熱をうばわれて転位密度が高く
なり、又低温度勾配にしようとすると、シード５
から例えばAsが抜け、Gaとなり、シードが溶け
落ちる欠点がある。
又ロ図に示す方法では、構造が複雑で、多数の
補助ヒーターを必要とし、又B2O3封止部の監視
がむつかしいという欠点がある。
（発明の開示）
本発明は上述の欠点を解消するため成されたも
ので、キヤツプをかぶせることにより、原料融液
からの揮発性構成元素の蒸発を容易に阻止して欠
陥の少ない均一性の高い単結晶が得られ、低温度
勾配を可能にして単結晶の転移を低減し、かつ操
作が簡単な化合物半導体単結晶の引上方法を提供
せんとするものである。
本発明は、チヨクラルスキー法により揮発性構
成元素を有する化合物半導体単結晶を引上げる方
法において、高さの大きいるつぼの内面に、その
内径より稍々小さい外径を有する逆斗状のキヤ
ツプを嵌めこみ、該キヤツプの管の上端に引上軸
を気密に接続し、前記管内にシード軸を通してシ
ードを取付け、前記るつぼと前記キヤツプの嵌合
部をB2O3融液でシールすると共に、前記キヤツ
プの管の上端部の温度を制御して前記揮発性構成
元素の蒸気圧を制御することを特徴とする単結晶
の引上方法である。
本発明において、揮発性構成元素を有する化合
物半導体とは、一種の蒸気圧の高い構成元素を持
つた化合物半導体、例えば周期律表の−族化
合物（例、GaAs、GaP、InAs、InP等）、−
族化合物（例、ZnS、CdS等）などの半導体であ
る。
以下、本発明を図面を用いてGaAs化合物半導
体の場合を例にとつて説明するが、本発明はこれ
に限定されるものではない。
第２図は本発明方法の実施例を説明するための
縦断面図である。図において第１図と同一の符号
はそれぞれ同一の部分を示す。図において、１１
は高さが十分長いるつぼ（例、熱変成BN製）
で、その内面に、その内径より稍々（0.5〜２mm）
小さい外径を有する逆斗状のキヤツプ１２が嵌
めこまれている。キヤツプ１２は細長い管１３を
持つ逆斗状で例えば石英等より成り、管１３の
上端はねじ１６等により引上軸４の下端に気密に
接続されている。この部分のキヤツプ１２の内側
と外側は気密でなくてはならない。又キヤツプ１
２の管１３の上端よりシード軸１４が管１３内を
通つて下方に伸び、下端にシード５が取付けられ
る。このようにキヤツプ１２は引上軸４、シード
軸１４と一体となつて回転するようになつてお
り、キヤツプ１２とるつぼ１１の内面とは同心度
が良く、回転中振れ合わないように精密に加工さ
れることが必要である。
このるつぼ１１とキヤツプ１２の嵌合部は
B2O3融液１５でおおつてシールされる。B2O3融
液１５はるつぼ１１とキヤツプ１２の隙き間に入
りこみ、るつぼ１１の内面とキヤツプ１２の外面
で、密閉された空間ができる。
次にキヤツプの管１３の上端部では、引上軸の
熱伝達率が高く、良く熱をうぼうので、GaAs原
料融液３中の揮発性構成元素Asの蒸気圧と単体
としてのAsの蒸気圧が等しくなる温度以下に下
がる。そこでキヤツプ１２内のAsの蒸気圧と融
液３中のAsの蒸気圧を等しくして融液３からの
Asの抜けを阻止するためには、管１３の上端部
を加熱してAsの蒸気圧を制御する必要がある。
この温度制御のため、熱電対１７および補助ヒー
ター１８が設けられている。熱電対１７は引上軸
４の中心を通つて引上軸と共に回転し、その出力
はスリツプリング（図示せず）により外部に取出
される。なおB2O3融液１５を通つてのAsの散逸
を補償するため過剰のAsを入れておくと、Asは
最も温度の低い管１３の上端部に過剰As１９と
して蒸着する。
このような装置により、熱電対１７の温度をヒ
ーター１８によつて調整することにより、原料融
液（GaAs）中の蒸発し易い元素（As）の蒸気圧
と平衡する蒸気圧で雰囲気が充たされる。
又るつぼ１１のキヤツプ１２の外側はこの圧力
と平衡する圧力の不活性ガス（例、N2ガス）で
おおわれている。
かような装置を用いて単結晶を育成するには、
予めキヤツプ１２の管１３の上端部の熱電対１７
の温度を、融液（例、GaAs）３中の蒸発し易い
元素（例、As）の蒸気圧と平衡する蒸気圧をそ
の元素（例、As）単体が持つような温度にして
おき、外部の付活性ガスの圧力もこの圧力に等し
くしておき、この状態を保持しながら、キヤツプ
１２と共に引上軸４を上下して種付けを行ない、
通常の方法と同様にして単結晶６を引上げる。
このようにすると、キヤツプ１２内のAs圧が
所定の圧力を維持するため、GaAs融液３中のAs
の蒸発抜けが阻止されて引上げ中融液の組成が一
定に保たれ、しかも雰囲気ガスの圧力は低くなる
（例、GaAsの場合、Asガス１気圧）ため、熱に
よる対流が少なくなるので、均一性の高い、低転
位密度の単結晶が得られる。
（実施例）
第２図に示すような本発明方法により、通常の
中圧炉（約10気圧まで）でGaAs単結晶をCZ法に
より引上げた。
るつぼ１１として熱変成BN製のものを用い、
内径10cm、高さ約25cmで、第２図に示すようにる
つぼの上方３cmの部分が内径10.6cmと広がつてい
るものを用いた。このるつぼ上方の広がつた部分
は、単結晶引上げ終了後B2O3をるつぼ内へ流し
落すためのものであり、これによりB2O3を周り
にこぼすことなく、単結晶を取り出すことができ
る。
キヤツプ１２として石英のものを用い、これに
BN製シード軸１４を図に示すようにねじ２０で
固着した。キヤツプ１２の下方のるつぼ１１に接
する部分の外径は9.85cmとした。
第３図イ，ロは実施例における工程順の状態を
示す断面図である。先ずイ図に示すようにるつぼ
１１内に１Kgの高純度GaAs多結晶２１および30
ｇのAs２２をチヤージし、キヤツプ１２上に約
200ｇのB2O3２３をチヤージした。初めに炉内を
N2ガス１気圧で充たし、（以下１気圧に調整され
る、）るつぼ１１を下に下げてるつぼ１１上部お
よびキヤツプ１２が主ヒーター２の中心近くにく
るようにしておき、GaAs２１およびAs２２の温
度を低く保つたままB2O3２３を溶解した。
B2O3２３が溶け、キヤツプ１２がB2O3融液１
５でシールされてから、熱電対１７（第２図）に
よる温度を615℃に固定し、徐々にるつぼ１１を
上方に上げ、ロ図に示すようにAsおよびGaAsを
主ヒーター２の中心部へ持つて行き、GaAsを溶
解した。この間、密閉部内（キヤツプ内）最低温
度部である熱電対１７の温度は補助ヒーター１８
（第２図）を使つて615℃に保持された。蒸発した
過剰Asはキヤツプの管１３の上端部（第２図）
へ蒸着した。615℃におけるAs蒸気圧PAsは約１
気圧であり、密閉部内のAs圧は１気圧になる。
キヤツプ１２外のN2ガス圧PN2は自動圧力調整器
により１気圧に固定されているので、密閉部内の
N2ガスは内部に存在できず、外に出てしまう。
なおこの間および引上げ中にAsも少しづつ外へ
もれるが、その量は引上げ後のるつぼ内残量等の
計測の結果、約20ｇであつた。
さてGaAsの融点（1238℃）におけるAs圧は約
１気圧であり、密閉部内ではGaAsからのAsの蒸
発は起こらない。この状態で、引上速度２mm／
時、引上軸回転数1rpm、るつぼ支持軸回転数
5rpmとして単結晶を引上げた。
第４図は単結晶引上げ中の状態を示す断面図で
ある。図において、補助ヒーター１８は外部容器
２４の予備のフランジ２５より固定され、又電力
を供給された。引合げ中は、B2O3溶液１５、石
英製キヤツプ１２を通して覗き窓２６で観察し
た。
得られた本発明の方法による単結晶は半絶縁性
を示し、重量約800ｇ、直径は51±２mmであつた。
本発明方法および従来のLEC法により得られ
た単結晶について、フロント部とバツク部よりウ
エハを切り出し、ウエハ面の溶融KOHによるエ
ツチピツト密度（EPD）を調査した結果は第５
図イ，ロに示す通りで、イ図はフロント部、ロ図
はバツク部を示す。図において左方は＜100＞方
向、右方は＜110＞方向への分布を示す。
第５図イ，ロより、本発明によるものは、フロ
ント部、バツク部共従来法によるものに比べ格段
にEPDが低く、かつばらつきも小さいことが分
る。
次に、上述の２種の単結晶について、フロント
部より切り出したウエハのFET（電界効果トラン
ジスター）評価を行なつた。FET評価は、2″φウ
エハの面内に第６図に示すようなFETを200μｍ
ごとに作つた。図において、２７はソース、２８
はドレイン、２９はゲートである。このような
FETで、オートプローバーによりソース−ドレ
イン間電流（Ids）、しきい値電圧（Vth）を求め
た。Siイオン注入は注入エネルギー60KeV、ド
ーズ量２×1012／cm2で行なつた。
結果は表１に示す通りである。
(Technical Field) The present invention relates to a method for pulling a compound semiconductor having a constituent element with a high vapor pressure (hereinafter referred to as a volatile constituent element) by the Czyochralski method (hereinafter referred to as the CZ method). (Background technology) In order to pull a single crystal of a compound semiconductor such as GaAs, which has As as a volatile constituent element, by the CZ method, the method shown in Figure 1 A and B is used. Ta. In the figure, a crucible 1 is heated by a main heater 2, and a raw material melt 3 is contained therein. A seed (seed crystal) 5 is attached to the lower end of the pulling shaft 4, and after the seed 5 is immersed in the surface of the raw material melt 3 and blended, the seed crystal 5 is pulled up while rotating to grow a single crystal 6. . In this case, the volatile constituent element (As
etc.) and keep the structure of the melt 3 at a stoichiometric composition, the surface of the raw material melt is covered with B 2 O 3 melt 7 as shown in Figure A, and the entire system is heated with high-pressure N. 2. Place the pulled part in a gas atmosphere, or place it in a container 8 with a volatile constituent element (such as As) pressure atmosphere as shown in Fig. 2, and seal the movable part with B 2 O 3 melt 9. Each section was heated with an auxiliary heater 10. However, in the method shown in Figure A, since As etc. diffuse through the high temperature B 2 O 3 melt 7, it is not possible to completely suppress the evaporation of volatile constituent elements from the raw material melt 3. Since high-pressure N 2 gas is used in the atmosphere, convection due to heat is intense, and the single crystal 6 that exits the B 2 O 3 melt 7 is suddenly deprived of heat, resulting in a high dislocation density and a low temperature gradient. Then, seed 5
For example, As falls out and becomes Ga, which has the disadvantage that the seeds melt away. Furthermore, the method shown in FIG. 2 has disadvantages in that it has a complicated structure, requires a large number of auxiliary heaters, and is difficult to monitor the B 2 O 3 sealing portion. (Disclosure of the Invention) The present invention has been made to solve the above-mentioned drawbacks, and by covering with a cap, it is possible to easily prevent the evaporation of volatile constituent elements from the raw material melt, thereby achieving uniformity with fewer defects. It is an object of the present invention to provide a method for pulling a compound semiconductor single crystal, which can obtain a high-temperature single crystal, enable a low temperature gradient to reduce the dislocation of the single crystal, and which is easy to operate. The present invention provides a method for pulling compound semiconductor single crystals containing volatile constituent elements by the Czyochralski method, in which an inverted cap having an outer diameter slightly smaller than the inner diameter is placed on the inner surface of a tall crucible. fitting, airtightly connecting a pulling shaft to the upper end of the tube of the cap, installing a seed through the seed shaft into the tube, sealing the fitting part of the crucible and the cap with a B 2 O 3 melt, The method for pulling a single crystal is characterized in that the vapor pressure of the volatile constituent elements is controlled by controlling the temperature at the upper end of the cap tube. In the present invention, a compound semiconductor having a volatile constituent element refers to a compound semiconductor having a constituent element with a high vapor pressure, such as a - group compound of the periodic table (e.g., GaAs, GaP, InAs, InP, etc.), −
semiconductors such as group compounds (e.g. ZnS, CdS, etc.). The present invention will be described below with reference to the drawings, taking the case of a GaAs compound semiconductor as an example, but the present invention is not limited thereto. FIG. 2 is a longitudinal sectional view for explaining an embodiment of the method of the present invention. In the figure, the same reference numerals as in FIG. 1 indicate the same parts. In the figure, 11
is a sufficiently long crucible (e.g. made of thermally modified BN)
Then, on its inner surface, there is a slight (0.5 to 2 mm) smaller than its inner diameter.
An inverted cap 12 having a small outer diameter is fitted. The cap 12 is in the shape of an inverted triangle and is made of, for example, quartz, with an elongated tube 13, and the upper end of the tube 13 is hermetically connected to the lower end of the lifting shaft 4 by a screw 16 or the like. This part of the cap 12 must be airtight inside and out. Also cap 1
A seed shaft 14 passes through the tube 13 and extends downward from the upper end of the tube 13 of No. 2, and the seed 5 is attached to the lower end. In this way, the cap 12 rotates together with the pulling shaft 4 and the seed shaft 14, and the cap 12 and the inner surface of the crucible 11 have good concentricity and are precisely aligned to prevent them from wobbling during rotation. It needs to be processed. The fitting part between the crucible 11 and the cap 12 is
Covered with B 2 O 3 melt 15 and sealed. The B 2 O 3 melt 15 enters the gap between the crucible 11 and the cap 12, and a sealed space is created between the inner surface of the crucible 11 and the outer surface of the cap 12. Next, at the upper end of the cap tube 13, the heat transfer coefficient of the pulling shaft is high and the heat is transferred well, so the vapor pressure of the volatile constituent element As in the GaAs raw material melt 3 and the vapor of As as a single substance are The temperature drops below which the pressure becomes equal. Therefore, by making the vapor pressure of As in the cap 12 equal to the vapor pressure of As in the melt 3, the vapor pressure of As in the melt 3 is made equal.
In order to prevent the escape of As, it is necessary to control the vapor pressure of As by heating the upper end of the tube 13.
A thermocouple 17 and an auxiliary heater 18 are provided for this temperature control. The thermocouple 17 passes through the center of the pulling shaft 4 and rotates together with the pulling shaft, and its output is taken out to the outside by a slip ring (not shown). Note that if excess As is added to compensate for the dissipation of As through the B 2 O 3 melt 15, As will be deposited as excess As 19 at the upper end of the tube 13 where the temperature is lowest. With such a device, by adjusting the temperature of the thermocouple 17 with the heater 18, the atmosphere is filled with a vapor pressure that is in equilibrium with the vapor pressure of the easily evaporable element (As) in the raw material melt (GaAs). . The outside of the cap 12 of the crucible 11 is covered with an inert gas (eg, N2 gas) at a pressure that is in equilibrium with this pressure. To grow a single crystal using such equipment,
Thermocouple 17 at the upper end of tube 13 of cap 12
The temperature of the element (e.g., As) is set to such a temperature that the element (e.g., As) alone has a vapor pressure that is in equilibrium with the vapor pressure of the easily evaporable element (e.g., As) in the melt (e.g., GaAs) 3, and The pressure of the activation gas is also set equal to this pressure, and while maintaining this state, the pulling shaft 4 is moved up and down together with the cap 12 to perform seeding.
The single crystal 6 is pulled up in the same manner as a normal method. In this way, since the As pressure in the cap 12 is maintained at a predetermined level, the As pressure in the GaAs melt 3 is
This prevents evaporation and keeps the composition of the melt constant during pulling, and the pressure of the atmospheric gas is lower (e.g., 1 atm of As gas in the case of GaAs), which reduces convection due to heat, resulting in a uniform A single crystal with high properties and low dislocation density can be obtained. (Example) According to the method of the present invention as shown in FIG. 2, a GaAs single crystal was pulled by the CZ method in a normal medium pressure furnace (up to about 10 atmospheres). A crucible made of thermally modified BN is used as the crucible 11,
The crucible used had an inner diameter of 10 cm and a height of about 25 cm, with the upper 3 cm of the crucible widening to an inner diameter of 10.6 cm as shown in Figure 2. This widening part above the crucible is for pouring the B 2 O 3 into the crucible after pulling the single crystal. This allows the single crystal to be taken out without spilling the B 2 O 3 around. can. A quartz cap is used as the cap 12, and
A BN seed shaft 14 was fixed with screws 20 as shown in the figure. The outer diameter of the lower portion of the cap 12 in contact with the crucible 11 was 9.85 cm. FIGS. 3A and 3B are cross-sectional views showing the state of the process order in the embodiment. First, as shown in Figure A, 1 kg of high purity GaAs polycrystals 21 and 30 are placed in a crucible 11.
Charge As22 of g and place approximately on cap 12.
200 g of B 2 O 3 23 was charged. First, look inside the furnace.
Fill the crucible with 1 atm of N 2 gas (adjusted to 1 atm below), lower the crucible 11 so that the top of the crucible 11 and the cap 12 are near the center of the main heater 2, and keep the temperature of GaAs 21 and As 22 23 of B 2 O 3 was dissolved while keeping the temperature low. B 2 O 3 23 melts, cap 12 becomes B 2 O 3 melt 1
5, the temperature is fixed at 615°C using the thermocouple 17 (Fig. 2), and the crucible 11 is gradually raised upwards to transfer As and GaAs to the center of the main heater 2 as shown in Fig. 5. I took it with me and melted the GaAs. During this time, the temperature of the thermocouple 17, which is the lowest temperature part in the sealed part (inside the cap), is lowered by the auxiliary heater 18.
(Figure 2) was used to maintain the temperature at 615°C. The evaporated excess As is removed from the upper end of the cap tube 13 (Fig. 2).
It was deposited on. As vapor pressure P As at 615℃ is approximately 1
Atmospheric pressure, and the As pressure inside the sealed area is 1 atm.
Since the N2 gas pressure P N2 outside the cap 12 is fixed at 1 atm by an automatic pressure regulator, the pressure inside the sealed area is
N2 gas cannot exist inside and escapes.
During this time and during pulling, As also leaked out little by little, and as a result of measuring the amount remaining in the crucible after pulling, the amount was approximately 20 g. Now, the As pressure at the melting point of GaAs (1238°C) is approximately 1 atm, and no evaporation of As from GaAs occurs within the sealed area. In this state, the pulling speed is 2mm/
time, pulling shaft rotation speed 1 rpm, crucible support shaft rotation speed
The single crystal was pulled at a speed of 5 rpm. FIG. 4 is a sectional view showing the state during single crystal pulling. In the figure, the auxiliary heater 18 is secured by a spare flange 25 of the outer container 24 and is also powered. During the inquiry, observation was made through the viewing window 26 through the B 2 O 3 solution 15 and the quartz cap 12 . The single crystal obtained by the method of the present invention exhibited semi-insulating properties, weighed about 800 g, and had a diameter of 51±2 mm. Regarding single crystals obtained by the method of the present invention and the conventional LEC method, wafers were cut from the front and back parts, and the etching pit density (EPD) of the wafer surface was investigated using molten KOH.
As shown in Figures A and B, Figure A shows the front part and Figure B shows the back part. In the figure, the left side shows the distribution in the <100> direction, and the right side shows the distribution in the <110> direction. From FIGS. 5A and 5B, it can be seen that the EPD of the present invention is much lower than that of the conventional method in both the front and back portions, and the variation is also small. Next, for the two types of single crystals mentioned above, FET (field effect transistor) evaluation was performed on the wafer cut out from the front part. For FET evaluation, we installed a 200 μm FET as shown in Figure 6 within the plane of a 2″φ wafer.
I made it for each. In the figure, 27 is the source, 28
is the drain, and 29 is the gate. like this
The source-drain current (Ids) and threshold voltage (Vth) of the FET were determined using an autoprober. Si ion implantation was performed at an implantation energy of 60 KeV and a dose of 2×10 12 /cm 2 . The results are shown in Table 1.
【表】
表１より、本発明方法によるものは、従来法に
よるものに比べ、Idsの分散およびVthのばらつ
きが格段に小さいことが分る。
（発明の効果）
上述のように構成された本発明の単結晶の引上
方法は次のような効果がある。
(イ) 高さの大きいるつぼの内面に、その内径より
稍々小さい外径を有する逆斗状のキヤツプを
嵌めこみ、該キヤツプの管の上端に引上軸を気
密に接続し、前記管内にシード軸を通してシー
ドを取付け、前記るつぼと前記キヤツプの嵌合
部をB2O3融液でシールするため、単結晶引上
部全体がるつぼ内面とキヤツプ内面で形成され
る密閉部内におかれると共に、前記キヤツプの
管の上端部の温度を制御して前記揮発性構成元
素の蒸気圧を制御することにより、原料融液上
の雰囲気の前記揮発性構成元素の蒸気圧と融液
中の上記元素の蒸気圧とを平衡させて、原料融
液からの揮発性構成元素の蒸発抜けを阻止し、
原料融液の化学量論的組成からのずれを防ぐの
で、結晶中に空孔（例、As）等の欠陥がなく、
均一性の高い電気的特性の良好な単結晶が得ら
れる。
(ロ) 従来の通常のLEC法では温度勾配を小さく
すると、前述のように揮発性構成元素が抜け、
シードが溶け落ちる欠点があつたが、本発明で
は上述の蒸気圧制御によりシードから揮発性構
成元素の抜けがなく、シードが溶け落ち恐れが
ないので、低温度勾配化が可能となり、これに
より低転位密度の単結晶が得られる。
(ハ) るつぼとキヤツプとその付属品を変えるだけ
で従来の通常の引上炉を使用して行なえるの
で、本発明方法を簡単に実施できる。例えば
GaAs単結晶の場合約１気圧が外圧としてかけ
られる炉であれば良く、又高圧炉を使えば
GaO、InP等の通常組成コントロールが難かし
い化合物単結晶でも、容易に組成コントロール
できる。[Table] From Table 1, it can be seen that the method according to the present invention has much smaller Ids dispersion and Vth variation than the conventional method. (Effects of the Invention) The single crystal pulling method of the present invention configured as described above has the following effects. (b) Fit an inverted cap having an outer diameter slightly smaller than the inner diameter into the inner surface of a crucible having a large height, connect a drawing shaft airtightly to the upper end of the tube of the cap, and insert it into the tube. In order to attach the seed through the seed shaft and seal the fitting part between the crucible and the cap with the B 2 O 3 melt, the entire single crystal pulling part is placed in a sealed part formed by the inner surface of the crucible and the inner surface of the cap, and By controlling the temperature at the upper end of the cap tube to control the vapor pressure of the volatile constituent element, the vapor pressure of the volatile constituent element in the atmosphere above the raw material melt and the element in the melt can be adjusted. By balancing the vapor pressure and preventing the evaporation of volatile constituent elements from the raw material melt,
Since deviation from the stoichiometric composition of the raw material melt is prevented, there are no defects such as vacancies (e.g., As) in the crystal.
A single crystal with high uniformity and good electrical properties can be obtained. (b) In the conventional normal LEC method, when the temperature gradient is reduced, volatile constituent elements are removed as mentioned above,
However, in the present invention, due to the vapor pressure control described above, volatile constituent elements do not escape from the seeds, and there is no risk of the seeds melting down, making it possible to achieve a low temperature gradient. A single crystal with high dislocation density is obtained. (c) The method of the present invention can be easily carried out because it can be carried out using a conventional pulling furnace by simply changing the crucible, cap, and their accessories. for example
In the case of GaAs single crystal, any furnace that can apply an external pressure of about 1 atm will suffice, and a high-pressure furnace will suffice.
The composition of single crystal compounds such as GaO and InP, which is normally difficult to control, can be easily controlled.
第１図イ，ロはそれぞれ従来の単結晶引上方法
の例を説明するための縦断面図である。第２図は
本発明方法の実施例を説明するための縦断面図で
ある。第３図イ，ロは本発明方法の実施例におけ
る工程順の状態を示す断面図である。第４図は本
発明方法の実施例における単結晶引上げ中の状態
を示す断面図である。第５図イ，ロは本発明方法
および従来法により得られた単結晶のウエハ面の
エツチピツト密度分布を示す図で、イ図はフロン
ト部、ロ図はバツク部を示す。第６図は本発明方
法の実施例により得られた基板に形成した電界効
果トランジスターの構造を示す図である。
１，１１……るつぼ、２……主ヒーター、３…
…原料融液、４……引上軸、５……シード、６…
…単結晶、７，９，１５……B2O3融液、８……
容器、１０，１８……補助ヒーター、１２……キ
ヤツプ、１３……管、１４……シード軸、１６，
２０……ねじ、１７……熱電対、１９……過剰
As、２１……GaAs多結晶、２２……As、２３
……B2A3、２４……外部容器、２５……フラン
ジ、２６……覗き窓、２７……ソース、２８……
ドレイン、２９……ゲート。
FIGS. 1A and 1B are longitudinal cross-sectional views for explaining examples of conventional single crystal pulling methods, respectively. FIG. 2 is a longitudinal sectional view for explaining an embodiment of the method of the present invention. FIGS. 3A and 3B are cross-sectional views showing the order of steps in an embodiment of the method of the present invention. FIG. 4 is a sectional view showing the state during single crystal pulling in an embodiment of the method of the present invention. FIGS. 5A and 5B are diagrams showing the etch pit density distribution on the wafer surface of single crystals obtained by the method of the present invention and the conventional method, in which FIG. 5A shows the front portion and FIG. 5B shows the back portion. FIG. 6 is a diagram showing the structure of a field effect transistor formed on a substrate obtained by an embodiment of the method of the present invention. 1, 11... Crucible, 2... Main heater, 3...
...raw material melt, 4...pulling shaft, 5...seed, 6...
...single crystal, 7,9,15...B 2 O 3 melt, 8...
Container, 10, 18... Auxiliary heater, 12... Cap, 13... Tube, 14... Seed shaft, 16,
20...screw, 17...thermocouple, 19...excess
As, 21...GaAs polycrystal, 22...As, 23
...B 2 A 3 , 24 ... external container, 25 ... flange, 26 ... viewing window, 27 ... source, 28 ...
Drain, 29...gate.
Claims (1)
有する化合物半導体単結晶を引上げる方法におい
て、高さの大きいるつぼの内面に、その内径より
稍々小さい外径を有する逆斗状のキヤツプを嵌
めこみ、該キヤツプの管の上端に引上軸を気密に
接続し、前記管内にシード軸を通してシードを取
付け、前記るつぼと前記キヤツプの嵌合部を
B2O3融液でシールすると共に、前記キヤツプの
管の上端部の温度を制御して前記揮発性構成元素
の蒸気圧を制御することを特徴とする単結晶の引
上方法。1. In a method of pulling a compound semiconductor single crystal having volatile constituent elements by the Czyochralski method, an inverted cap having an outer diameter slightly smaller than the inner diameter is fitted into the inner surface of a tall crucible, A pulling shaft is airtightly connected to the upper end of the tube of the cap, a seed is attached through the seed shaft into the tube, and the fitting part of the crucible and the cap is connected.
A method for pulling a single crystal, comprising sealing with a B 2 O 3 melt and controlling the temperature at the upper end of the cap tube to control the vapor pressure of the volatile constituent elements.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18577283A JPS6077196A (en) | 1983-10-03 | 1983-10-03 | Method for pulling up single crystal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18577283A JPS6077196A (en) | 1983-10-03 | 1983-10-03 | Method for pulling up single crystal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6077196A JPS6077196A (en) | 1985-05-01 |
| JPH0329755B2 true JPH0329755B2 (en) | 1991-04-25 |
Family
ID=16176614
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18577283A Granted JPS6077196A (en) | 1983-10-03 | 1983-10-03 | Method for pulling up single crystal |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6077196A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61275186A (en) * | 1985-05-29 | 1986-12-05 | Hitachi Cable Ltd | Single crystal pulling device |
-
1983
- 1983-10-03 JP JP18577283A patent/JPS6077196A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6077196A (en) | 1985-05-01 |
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