JPH02233581A - Crystal growth - Google Patents
Crystal growthInfo
- Publication number
- JPH02233581A JPH02233581A JP5578189A JP5578189A JPH02233581A JP H02233581 A JPH02233581 A JP H02233581A JP 5578189 A JP5578189 A JP 5578189A JP 5578189 A JP5578189 A JP 5578189A JP H02233581 A JPH02233581 A JP H02233581A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- crystal
- melt
- solid
- pulling
- 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.)
- Pending
Links
- 239000013078 crystal Substances 0.000 title claims abstract description 101
- 238000000034 method Methods 0.000 claims abstract description 73
- 239000007787 solid Substances 0.000 claims abstract description 58
- 239000000155 melt Substances 0.000 claims abstract description 43
- 230000008569 process Effects 0.000 claims abstract description 27
- 238000002844 melting Methods 0.000 claims abstract description 11
- 230000008018 melting Effects 0.000 claims abstract description 11
- 239000012535 impurity Substances 0.000 claims description 59
- 239000007788 liquid Substances 0.000 claims description 36
- 230000007423 decrease Effects 0.000 claims description 6
- 238000002109 crystal growth method Methods 0.000 claims description 4
- 239000002994 raw material Substances 0.000 abstract description 29
- 239000008710 crystal-8 Substances 0.000 abstract description 8
- 238000005188 flotation Methods 0.000 abstract 2
- 238000010309 melting process Methods 0.000 abstract 1
- 238000005204 segregation Methods 0.000 description 14
- 238000009826 distribution Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 6
- 230000008859 change Effects 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- 239000010703 silicon Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 239000013256 coordination polymer Substances 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Landscapes
- Crystals, And After-Treatments Of Crystals (AREA)
- Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、主に半導体材料として用いられているシリコ
ン単結晶等の結晶成長方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for growing crystals such as silicon single crystals, which are mainly used as semiconductor materials.
一般にこの種の単結晶の成長方法としては、従来チジク
ラルスキー法(CZ法)が広く用いられている。第4図
cよcz法による単結晶の製造状態を示す模式図であり
、例えばチャンバ内に配した坩堝2内に結晶用原料を投
入し、これをヒータ3にて加熱溶融せしめた後、この溶
融液NL中に引上げ軸6にて吊り下げた種結晶7を浸し
、これを回転させつつ上方に引上げて種結晶7の下端に
単結晶8を成長せしめることによって行なわれる。In general, as a method for growing this type of single crystal, the Czychralski method (CZ method) has been widely used. FIG. 4c is a schematic diagram showing the manufacturing state of a single crystal by the cz method. For example, a raw material for crystal is put into a crucible 2 placed in a chamber, and after being heated and melted by a heater 3, this This is carried out by immersing a seed crystal 7 suspended by a pulling shaft 6 into the melt NL and pulling it upward while rotating it to grow a single crystal 8 at the lower end of the seed crystal 7.
ところで通常単結晶を半導体基板等として用いる場合は
、単結晶の電気抵抗率,電気電導型を調節するために、
坩堝内の溶融液中には不純物元素を添加するが、このよ
うな不純物は単結晶の引上げ方向に偏析し、単結晶の成
長方向全長にわたって均一な濃度分布を維持することは
極めて難しい.不純物の偏折は溶融液と単結晶との成長
界面における単結晶中の不純物濃度C,と溶融液中の不
純物濃度CLとの比Cs/CL、即ち実効偏析係数ke
が1とならないことに起因し、これは単結晶の成長に伴
う溶融液中の不純物濃度、単結晶中の不純物濃度が結晶
引上げ途中で変化することによる。By the way, when a single crystal is normally used as a semiconductor substrate, etc., in order to adjust the electrical resistivity and electrical conductivity type of the single crystal,
Impurity elements are added to the melt in the crucible, but these impurities segregate in the pulling direction of the single crystal, and it is extremely difficult to maintain a uniform concentration distribution over the entire length of the single crystal in the growth direction. Segregation of impurities is determined by the ratio Cs/CL between the impurity concentration C in the single crystal and the impurity concentration CL in the melt at the growth interface between the melt and the single crystal, that is, the effective segregation coefficient ke.
is not 1, and this is because the impurity concentration in the melt as the single crystal grows and the impurity concentration in the single crystal change during the crystal pulling process.
このような偏析を抑制する方法として溶融層法が知られ
ている。第5図は一般的な溶融層法の実施状態を示す模
式図であり、坩堝2内の上方に位置して結晶用原料の溶
融液層Lと、またその下部に位置して溶融液層Lと実質
的に同質の結晶用原料である固体層Pとを共存させた状
態で溶融液層Lから単結晶8の引上げを行う方法である
。A fused layer method is known as a method for suppressing such segregation. FIG. 5 is a schematic diagram showing the implementation state of the general molten layer method, in which a molten liquid layer L of the raw material for crystallization is located above the crucible 2, and a molten liquid layer L is located below it. In this method, the single crystal 8 is pulled from the molten liquid layer L in a state in which the solid layer P, which is a material for crystal of substantially the same quality as the solid layer P, coexists with the molten liquid layer L.
なお、この単結晶8の引上げ過程では途中ヒータ3の制
御によって単結晶8の引上げに伴う溶融液層Lの厚さの
減少を固体層Pの溶融により補充して溶融液層Lの体積
を一定に保持し、不純物元素は単結晶引上げ過程で連続
的に添加し、溶融液層L中の不純物濃度を一定に維持す
る方法(溶融層厚一定法という、特公昭34−8242
号公報)、或いは意図的に溶融液層Lの体積を変化させ
、単結晶引上げ中は不純物元素を添加することなく溶融
液層L中の不純物濃度を一定に維持する方法がある(溶
融層厚変化法という)。In addition, during the process of pulling the single crystal 8, by controlling the heater 3, the decrease in the thickness of the molten liquid layer L due to the pulling of the single crystal 8 is compensated for by melting the solid layer P, and the volume of the molten liquid layer L is kept constant. A method of keeping the impurity concentration in the melt layer L constant by continuously adding impurity elements during the single crystal pulling process (constant melt layer thickness method, Japanese Patent Publication No. 34-8242)
Alternatively, there is a method in which the volume of the melt layer L is intentionally changed and the impurity concentration in the melt layer L is maintained constant without adding impurity elements during single crystal pulling (melt layer thickness (called the change method).
この溶融層法を用いて不純物の偏折なく単結晶を引上げ
るための条件は本発明者の解析によれば概略次の如くに
して求め得る。According to the inventor's analysis, the conditions for pulling a single crystal without deflection of impurities using this molten layer method can be roughly determined as follows.
第5図に示す単結晶引上げ過程における坩堝2内の溶融
液層Lと固体層Pとの層厚さの推移を示す第6図(イ)
〜(ホ)の一次元モデル図を用いて説明する。Figure 6 (a) shows the change in layer thickness of the molten liquid layer L and the solid layer P in the crucible 2 during the single crystal pulling process shown in Figure 5.
This will be explained using one-dimensional model diagrams of ~(e).
第6図(イ)は坩堝に対する原料のチャージ直後の状態
を、また第6図(口)は初期溶解終了時の状態を、第6
図(ハ),(二)は結晶引上げ中における状態を、更に
第6図(ホ)は結晶引上げ終了時の状態を夫々示してい
る。Figure 6 (a) shows the state immediately after charging the crucible with raw materials, and Figure 6 (opening) shows the state at the end of the initial melting.
Figures (C) and (2) show the state during crystal pulling, and Figure 6 (E) shows the state at the end of crystal pulling.
第6図(イ)に示す如く最初に坩堝にチャージした原料
の重量を1(=fF)とし、原料上面側から底面側に向
けて測った重量比Xの位置における不純物濃度をCP(
X)とする。As shown in FIG. 6(a), the weight of the raw material initially charged in the crucible is 1 (=fF), and the impurity concentration at the position of the weight ratio X measured from the top side of the raw material toward the bottom side is CP (
X).
第6図(イ)に示す如く結晶用原料を坩堝にチャージし
た後、これをその上面側から溶融し、第6図(口)に示
す如く坩堝上部に融液率fL (=fo)の溶融液層L
と、またその下部に固体率r,の固体層Pとを共存させ
、次いで溶融液1iLから単結晶の引上げを行う。初期
チャージ原料重量1に対する引上げた単結晶の重量比(
結晶引上げ率)がf3のときおける溶融液層の重量比(
融液率)をf,、固体として残っている原料の重量比(
固体率)をr,とし、また初期溶融液層L中の不純物濃
度をCo、不純物添加後における結晶一溶融液界面にお
ける固相中の不純物濃度をCs、また液相中不純物濃度
をC,とする。As shown in Fig. 6 (a), after charging the raw material for crystal into the crucible, it is melted from the upper surface side, and as shown in Fig. 6 (opening), the melting liquid at the melt rate fL (=fo) is deposited on the upper part of the crucible. liquid layer L
and a solid layer P having a solid fraction r are made to coexist below it, and then a single crystal is pulled from 1 iL of the melt. Weight ratio of pulled single crystal to initial charge raw material weight 1 (
When the crystal pulling rate) is f3, the weight ratio of the melt layer (
f, the weight ratio of the raw material remaining as a solid (melt ratio)
Let the impurity concentration in the initial melt layer L be Co, the impurity concentration in the solid phase at the crystal-melt interface after adding the impurity be Cs, and the impurity concentration in the liquid phase be C. do.
いま第6図(ハ)に示す如く単結晶.溶融液層.固体層
が夫々結晶引上げ率【,、融液率f,、固体率f,で存
在するものとすると、結晶引上げ率f3+融液率fL+
固体率f,間には下記(1)式が成立する。Now, as shown in Figure 6 (c), it is a single crystal. Molten liquid layer. Assuming that each solid layer exists at a crystal pulling rate [,, melt rate f,, solid rate f, then crystal pulling rate f3 + melt rate fL+
The following equation (1) holds true between the solid fraction f.
(,−+lL+f,−f.+f,=1 ・・・(1)
但しr,+t,−r0
第6図(ハ)の状態から単結晶をその引上げ率がf,か
ら第6図(二)に示す如<rs+Δ『,となるまで引上
げる間に融液率がfLからfL+Δ『,に、また圃体率
がf,からf,+Δf,に変化したとし、更にこの間の
不純物添加量をc1・Δfs (但し、c,:結晶化
率に対する単位不純物添加量)とすると、第6図(ハ)
の状態から第6図(二)の状態に至る過程において、溶
融液層L中の不純物濃度C,、は一様、また固体層P中
への不純吻の拡散は零と考えられるから、第6図(ハ)
,(二)におけるA領域の不純物は保存され、これらの
間には下記(2)弐が成立する。(,-+lL+f,-f.+f,=1...(1)
However, r, +t, -r0 The melt rate is Assume that the field rate changes from fL to fL+Δ′, and from f, to f,+Δf, and the amount of impurity added during this period is c1・Δfs (where c, is the unit amount of impurity added to the crystallization rate). Then, Figure 6 (c)
In the process from the state to the state shown in Figure 6 (2), the impurity concentration C, in the molten liquid layer L is uniform, and the diffusion of impurity into the solid layer P is considered to be zero. Figure 6 (c)
, (2), the impurities in the A region are preserved, and the following (2) 2 holds between them.
c,− rL+c, ・Δf3+CP ・Δro=C
,・Δf,+ (C,+ΔCL) ・ (rt+Δr
t) ・・・(2)
単結晶一溶融液界面における固相中不純物濃度C,と液
相中不純物濃度CLとの間には下記(3)弐の関係が成
立す・るから、
Cs ”ke’ CL =(33
但し、ke:偏析係数
(2)式中の二次の微小項を省略し、(3)式を適用す
ると下記(4)式が得られる。c, - rL+c, ・Δf3+CP ・Δro=C
,・Δf,+ (C,+ΔCL) ・(rt+Δr
t) ...(2) Since the following relationship (3) 2 holds between the impurity concentration C in the solid phase and the impurity concentration CL in the liquid phase at the single crystal-melt interface, Cs ''ke' CL = (33 where ke: segregation coefficient Omitting the second-order minute term in equation (2) and applying equation (3) yields equation (4) below.
而して溶融層法において無偏析条件は(4)式中のdC
t /d fs =0, Cp ”0として下記(5)
式で与えられる。Therefore, in the fused layer method, the non-segregation condition is dC in equation (4).
Assuming t/d fs = 0, Cp ”0, the following (5)
It is given by Eq.
結晶の引上げ過程で固体層Pを溶融し、溶融液層Lの厚
さを一定に維持する溶融層厚一定決ではd fL/d
rs =Oであるから下記(6)式で表わされる不純物
を連続的に添加すれば上記(5)弐の条件を満足するこ
とが可能となる。When the solid layer P is melted during the crystal pulling process and the thickness of the molten liquid layer L is kept constant, d fL/d
Since rs = O, the second condition of (5) above can be satisfied by continuously adding an impurity represented by the following formula (6).
C@ =keCL=keCo ・・・(6)一方溶
融液厚変化法では不純吻を連続添加せず(C− =0)
、d fL/d fs =−keが満たされるよう結
晶引上げに伴って溶融液層厚を下記(7)式を満足する
よう変化させればよい。C@ = keCL = keCo ... (6) On the other hand, in the melt thickness variation method, impurity is not continuously added (C- = 0)
, d fL/d fs =-ke may be satisfied by changing the melt layer thickness as the crystal is pulled so as to satisfy the following equation (7).
f L va f L.−ke−f 3 ・・・(
7)但しf LO :初期融液率
多くの場合不純物の実効偏析係数keは1より小さいか
らfLo−keと設定することにより最後まで無偏析条
件を維持することができる。f L va f L. -ke-f 3...(
7) However, fLO: Initial melt rate In many cases, the effective segregation coefficient ke of impurities is smaller than 1, so by setting fLo-ke, segregation-free conditions can be maintained until the end.
なお固体層が全部溶融した時点以後は無偏析条件が成立
せず、下記(8)式に従って偏析が進行する。Note that after the solid layer is completely melted, the no-segregation condition is not established, and segregation progresses according to the following equation (8).
Cs −keCo ( 1 f s ) ”−’
”’(8)但し、C0 :初期溶融液層中不純物濃
度第7図は溶融層厚法において前述した無偏析条件を成
立させるための温度制御の例を示す説明図であり、第7
図(イ)は坩堝及び坩堝内の溶融液層,固体層の厚さ寸
法を、また第7図(口)は温度分布を示しており、定性
的には以下のように説明される。Cs −keCo (1 f s ) ”−’
"'(8) However, C0: Initial concentration of impurities in the melt layer. FIG.
Figure (a) shows the thickness dimensions of the crucible and the molten liquid layer and solid layer in the crucible, and Figure 7 (opening) shows the temperature distribution, which can be qualitatively explained as follows.
ヒータから溶融液層に供給される熱量は、単結晶を通し
ての伝導熱、溶融液表面からの輻射熱等の熱量Q,Jと
、坩堝2内の原料,坩堝軸2cを介して放散される伝導
熱NQLとの和となる。熱量Quは結晶引上条件を安定
させるために引上期間を通じて略一定になるよう設定さ
れるものとする。またヒータの電力(発熱量)は略一定
であり熱IQLも一定であるとすると、これから下記(
9)弐が成立する。The amount of heat supplied from the heater to the molten liquid layer includes the amount of heat Q, J such as conductive heat through the single crystal, radiant heat from the surface of the melt, etc., and the conductive heat dissipated via the raw material in the crucible 2 and the crucible axis 2c. It becomes the sum with NQL. The amount of heat Qu is set to be approximately constant throughout the pulling period in order to stabilize the crystal pulling conditions. Also, assuming that the electric power (heat amount) of the heater is approximately constant and the thermal IQL is also constant, the following (
9) 2 is established.
= h (Tb − Tp )
但し、
T,:溶融液層と固体層との境界温度
(結晶原料の融点で決まる一定値)
T0 :坩堝軸下部の温度(通常は略一定値)λ,:固
体層の熱伝導率
Sc :坩堝内断面積
h :固体層から坩堝軸への熱通過率
λP ;坩堝軸の熱伝導率
1P :チャンバ内の坩堝軸の長さ
(9)式はこれからT,,T,を消去すると下記α0式
の如くになる。= h (Tb − Tp) However, T,: Boundary temperature between the molten liquid layer and the solid layer (a constant value determined by the melting point of the crystal raw material) T0: Temperature at the lower part of the crucible axis (usually a substantially constant value) λ,: Solid Thermal conductivity of the layer Sc: Internal cross-sectional area of the crucible h: Heat transfer rate from the solid layer to the crucible axis λP; Thermal conductivity of the crucible axis 1P: Length of the crucible axis inside the chamber Equation (9) can be calculated from T, When T, is eliminated, the following α0 formula is obtained.
Q, λh Sc h λ
P SF通常の結晶引上げ過程では溶融液表面の位置
は一定に、即ち第7図(イ)においてe=一定に維持さ
れるからΔJt+Δβ,+Δ1F=0である。Q, λh Sc h λ
P SF In the normal crystal pulling process, the position of the melt surface is kept constant, that is, e=constant in FIG. 7(a), so ΔJt+Δβ, +Δ1F=0.
また、下記αυ式が成立し、
Δl, 八f,
Δf,+Δfc+Δf,=0であるがらΔ(,ocΔN
,が成立する。In addition, the following αυ formula holds true, and while Δl, 8f, Δf, +Δfc+Δf, = 0, Δ(,ocΔN
, holds true.
従ってαΦ式から下記(財)弐を得る,ΔfL
Δf,+Δf,
Δf, Δf!
’p S.
これから固体層の熱の伝え易さλ6 5Cと、坩堝軸2
cの熱の伝え易さλP SPとが等しければ溶融液層厚
を一定に維持出来、またλ,S,〉λ6 scであれば
溶融液層厚さは引上げに伴って減少することとなり、溶
融液層厚の制御が可能となる。Therefore, we obtain the following (goods) 2 from the αΦ formula, ΔfL
Δf, +Δf, Δf, Δf! 'pS. From now on, the heat conductivity of the solid layer is λ6 5C, and the crucible axis 2
If the heat conductivity of c is equal to λP and SP, the melt layer thickness can be maintained constant, and if λ, S, > λ6 sc, the melt layer thickness will decrease as it is pulled up, and the melt It becomes possible to control the liquid layer thickness.
溶融層法では上述した如き条件に従う限り理論上は単結
晶中の不純物濃度分布を均一化し得るはずである。しか
しこの溶融層法では坩堝2内に装入した原料全体を単結
晶化することは難しく、特に半導体用材料としてのシリ
コン原料は固体の密度が溶融液の密度よりも小さいため
、固体層の厚さが一定値以下になると固体層が溶融液層
中に浮遊し、溶融液層の振動,温度変動を招き、単結晶
の引上げの障害となる。このため坩堝内に相当量の原料
(固体層,融液率rs)を残した状態で単結晶の引上げ
を停止せざるを得す、原料の歩留りが悪いという問題が
あった。Theoretically, the fused layer method should be able to make the impurity concentration distribution in a single crystal uniform as long as the above-mentioned conditions are followed. However, with this molten layer method, it is difficult to single-crystallize the entire raw material charged into the crucible 2. In particular, silicon raw materials used as semiconductor materials have a solid density lower than that of the molten liquid, so the thickness of the solid layer When the temperature falls below a certain value, the solid layer floats in the molten layer, causing vibrations and temperature fluctuations in the molten layer, which impede the pulling of the single crystal. For this reason, the pulling of the single crystal had to be stopped with a considerable amount of raw material (solid layer, melt ratio rs) left in the crucible, resulting in a problem of poor raw material yield.
本発明はかかる事情に鑑みなされたものであって、その
目的とするところは溶融層法とCZ法とを組合わせるこ
とによって結晶用原料の歩留り低下の要因となっている
固体層の浮遊に影響されることなく、結晶の引上げを可
能とし、歩留りの大幅な向上を図れるようにした結晶成
長方法を提供するにある。The present invention was made in view of the above circumstances, and its purpose is to combine the fused layer method and the CZ method to influence the floating of the solid layer, which is a factor in reducing the yield of crystal raw materials. It is an object of the present invention to provide a crystal growth method that enables the crystal to be pulled up without being damaged, thereby significantly improving the yield.
本発明に係る結晶成長方法は、チャンバ内に配した坩堝
内に、溶融液層と、該溶融液層下に位置するこれと略同
質の固体層とを共存させた状態で溶融層厚さを制御しつ
つ前記溶融液層から一の結晶を引上げ、前記固体層がそ
の層厚さの減少により熔融液層内に浮遊するに先立って
前記一の結晶の引上げを終了する過程と、坩堝内に残留
する固体層を全て溶融する過程と、この過程と同時又は
その前後で引上げた一の結晶をチャンバ外へ取り出す過
程と、固体層を全て溶融せしめた状態の溶融液層から他
の結晶を引上げる過程とを含むことを特徴とする。In the crystal growth method according to the present invention, the thickness of the molten layer is determined by coexisting a molten liquid layer and a solid layer of substantially the same quality as the molten liquid layer located below the molten liquid layer in a crucible placed in a chamber. pulling a crystal from the melt layer in a controlled manner and finishing the pulling of the crystal before the solid layer becomes suspended in the melt layer due to a decrease in the layer thickness; A process of melting all remaining solid layers, a process of taking out one crystal pulled out of the chamber at the same time or before or after this process, and pulling other crystals from the molten liquid layer in a state where all the solid layers have been melted. It is characterized by including the process of raising.
本発明にあってはこれによって、溶融層法によろ過程で
は不純物の偏析のない結晶を引上げ得、またCZ法によ
る過程では不純物の偏析は存在するが残留原料が殆ど存
在しない状態に迄結晶を引上げることが可能となる。In the present invention, as a result of this, it is possible to pull crystals with no segregation of impurities in the molten layer process, and to pull crystals to a state where impurity segregation exists but with almost no residual raw material in the CZ process. It becomes possible to pull it up.
以下本発明をその実施例を示す図面に基づき具体的に説
明する。第1図は本発明方法の実施状態を示す結晶成長
装置の模式的縦断面図であり、図中1はチャンバ、2は
坩堝、3はヒータ、4はシャッタ、5はプルチャンバ、
1lは固体原料の供給器を示している。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof. FIG. 1 is a schematic vertical cross-sectional view of a crystal growth apparatus showing the implementation state of the method of the present invention, in which 1 is a chamber, 2 is a crucible, 3 is a heater, 4 is a shutter, 5 is a pull chamber,
1l indicates a solid raw material feeder.
チャンバ1の内部中央に坩堝2が配設され、この坩堝2
と保温材との間にヒータ3が、またチャンバ1の上部壁
には坩堝2上に面してシャッタ4にて開閉される筒体1
aが立設してあり、この筒体1a上には着脱可能にプル
チャンバ5が立役せしめられている。A crucible 2 is disposed in the center of the chamber 1, and the crucible 2
A heater 3 is installed between the chamber 1 and the heat insulating material, and a cylinder 1 is mounted on the upper wall of the chamber 1, facing the crucible 2 and opened and closed by a shutter 4.
a stands upright, and a pull chamber 5 is removably erected on top of this cylindrical body 1a.
坩堝2は石英製の内坩堝2aの外周にグラファイト製の
外坩堝2bを配した二重構造に構成されており、その底
部中央にはチャンバ1の底壁を貫通させた軸2cの上端
が連結され、該軸2cにて回転させつつ昇降せしめられ
るようになっている。The crucible 2 has a double structure with an inner crucible 2a made of quartz and an outer crucible 2b made of graphite arranged around the outer periphery of the crucible 2, and the upper end of a shaft 2c penetrating the bottom wall of the chamber 1 is connected to the center of the bottom of the crucible 2. It is designed so that it can be raised and lowered while being rotated by the shaft 2c.
プルチャンバ5の上方には回転、昇降機構(図示せず)
に連繋された引上げ軸6の上端が導入され、その下端に
はチャックに掴持させた種結晶7が吊設され、この種結
晶7を坩堝2内の溶融液層Lになじませた後、回転させ
つつ上昇させることによって、種結晶7の下端にシリコ
ンの単結晶8。を成長せしめるようになっている。Above the pull chamber 5 is a rotating and lifting mechanism (not shown).
The upper end of the pulling shaft 6 connected to the is introduced, and a seed crystal 7 held by a chuck is suspended from the lower end of the pulling shaft 6. After the seed crystal 7 is blended into the molten liquid layer L in the crucible 2, By rotating and raising the silicon single crystal 8 at the lower end of the seed crystal 7. It is designed to encourage growth.
固体原料の供給器11は、秤量器,ホッパ(いずれも図
示せず)及び原料投入管11aを備えており、原料投入
管11aの下端はチャンバ1を通して坩堝2内の周縁部
寄りの上方に臨ませてあり、ホッパから落下した原料は
秤量器を経て原料投入管11aの上端に投入され、ここ
から坩堝2内に供給されるようになっている。The solid raw material feeder 11 is equipped with a weigher, a hopper (none of which is shown), and a raw material input pipe 11a, and the lower end of the raw material input pipe 11a passes through the chamber 1 and faces upward toward the periphery of the crucible 2. The raw material that has fallen from the hopper is fed into the upper end of the raw material input pipe 11a via a weighing device, and is supplied into the crucible 2 from here.
なお、図面には示していないが不純物についての供給器
も同様にして設けられている。Although not shown in the drawings, a supply device for impurities is also provided in the same manner.
而して本発明方法における主要過程を第2図(イ)〜(
へ)に示す一次元モデルに基づいて説明する。The main steps in the method of the present invention are shown in Figures 2(a) to 2(a).
The explanation will be based on the one-dimensional model shown in ).
第2図は本発明方法の主要過程における坩堝内の溶融液
層,固定層及び単結晶の各割合の推移を示す一次元モデ
ルとして示した説明図であり、以下溶融層法による第1
の単結晶を引上げる過程と、CZ法による第2の単結晶
を引上げる過程とに分けて説明する。FIG. 2 is an explanatory diagram showing a one-dimensional model showing the changes in the proportions of the molten liquid layer, fixed layer, and single crystal in the crucible in the main process of the method of the present invention.
The process of pulling the second single crystal using the CZ method and the process of pulling the second single crystal using the CZ method will be explained separately.
〔溶融層法による第1の単結晶の引上げ過程〕■ 先ず
第1図に示す供給器11を通じて坩堝2内に結晶用の固
体原料、例えば高純度の多結晶シリコン(不純物濃度C
,=Oとする)をチャージする(第2図(イ))。[Process of pulling the first single crystal using the molten layer method] ■ First, a solid raw material for crystals, such as high-purity polycrystalline silicon (impurity concentration C
, = O) (Fig. 2 (a)).
■ 次にチャンバ1内の雰囲気ガスを不活性ガス等と置
換した後、ヒータ3の電力を溶解条件に設定し、チャー
ジされた固体原料の溶解を行う。(2) Next, after replacing the atmospheric gas in the chamber 1 with an inert gas or the like, the electric power of the heater 3 is set to the melting condition, and the charged solid raw material is melted.
チャージした固体原料は予め定めた初期融液率r,。が
得られる迄溶融し、溶融液中には図示しない不純物供給
器から溶融液中の不純物濃度がC0となるよう不純物を
添加する。これにより、初期融液率fLo、不純物濃度
C0の溶融液層Lと、その下部に位置する固体率fP+
不純物濃度C,の固体層Pとが共存する状態に設定す
る。The charged solid raw material has a predetermined initial melt rate r. An impurity is added to the melt from an impurity supply device (not shown) so that the impurity concentration in the melt becomes C0. This creates a melt layer L with an initial melt rate fLo and an impurity concentration C0, and a solid rate fP+ located below it.
A state is set in which a solid layer P with an impurity concentration C coexists.
■ 結晶の引上げを開始し、これに伴う溶融液層Lの厚
さの減少は固体NPの溶融によって補充する.
そして固体層Pの層厚が減少して固体層Pが溶融液層L
中へ浮遊し始めるに先立って単結晶の引上げを終了する
。このときの単結晶の結晶引上げ率はfS+結晶中の不
純物濃度はC,。とすると、溶融液層Lの融液率はfL
,不純物濃度はCG、固体層Pの固体率がfP+不純物
濃度はC,である。■ The crystal starts to be pulled up, and the accompanying decrease in the thickness of the molten liquid layer L is replenished by melting the solid NP. Then, the layer thickness of the solid layer P decreases, and the solid layer P becomes the molten liquid layer L.
Finish pulling the single crystal before it begins to float inside. At this time, the crystal pulling rate of the single crystal is fS + the impurity concentration in the crystal is C. Then, the melt rate of the melt layer L is fL
, the impurity concentration is CG, the solid rate of the solid layer P is fP+the impurity concentration is C.
■ 引上げた単結晶8はシャフタ4内を通してプルチャ
ンバ5内に引き込んだ後、シャッタ4を閉じる。(2) After the pulled single crystal 8 is drawn into the pull chamber 5 through the shutter 4, the shutter 4 is closed.
これによって溶融層法による第1の単結晶の引上げ過程
が終了する。This completes the process of pulling the first single crystal using the fused layer method.
■ 残った坩堝2内の溶融液層L1固体層Pはヒータ制
御によって固体層Pが全て溶融される迄加熱し、全体を
溶融液層Lとする。この溶融液層Lの融液率はf,不純
物濃度は固体層Pの溶融によってC0′となる。(2) The remaining molten liquid layer L1 solid layer P in the crucible 2 is heated by heater control until the solid layer P is completely melted, and the entire solid layer P is made into a molten liquid layer L. The melt rate of this melt layer L becomes f, and the impurity concentration becomes C0' due to the melting of the solid layer P.
CCZ法による第2の単結晶の引上げ過程〕■ 溶融液
層の不純物の濃度C′から予測される単結晶中の不純物
濃度分布が第2の単結晶について設定すべき不純物濃度
分布と一致する場合はそのまま種結晶7を坩堝2内の溶
融液層中に浸漬し、単結晶の引上げを開始してもよいが
、異なる不純物濃度分布の第2の単結晶を得ようとする
場合には、溶融液NL内に不純物元素を投入し、溶融液
層の不純物濃度を00とする。Step of pulling the second single crystal using the CCZ method] ■ When the impurity concentration distribution in the single crystal predicted from the impurity concentration C' in the melt layer matches the impurity concentration distribution to be set for the second single crystal. The seed crystal 7 may be immersed as it is in the molten liquid layer in the crucible 2 to start pulling the single crystal, but if you want to obtain a second single crystal with a different impurity concentration distribution, An impurity element is introduced into the liquid NL, and the impurity concentration of the molten liquid layer is set to 00.
■ 溶融液層内の不純物濃度を00に設定した後は第5
図に示したCZ法による第2の単結晶の引上げを溶融液
が無くなるまで行う。■ After setting the impurity concentration in the melt layer to 00,
The second single crystal is pulled by the CZ method shown in the figure until the melt runs out.
Cz法においては固体層は無いからfy”’O.またΔ
fL+Δf,−o.c.=oであるから(4)式は下記
α1式の如くに表せる。In the Cz method, there is no solid layer, so fy"'O. Also, Δ
fL+Δf, -o. c. =o, so equation (4) can be expressed as the following α1 equation.
d l 3
従って単結晶中の不純物濃度C3は下記aa式で与えら
れる状態で偏析することとなる。d l 3 Therefore, the impurity concentration C3 in the single crystal is segregated in a state given by the following aa formula.
C3 −keCo(1 − f s)”−’ =Q4
)これによって不純物濃度が03。で結晶成長方向に略
一定した第1の単結晶と、不純物濃度が前記α旬式で表
されるC,で偏析した状態の第2の単結晶が得られるこ
ととなる。C3-keCo(1-fs)"-'=Q4
) This makes the impurity concentration 03. Thus, a first single crystal whose impurity concentration is substantially constant in the crystal growth direction and a second single crystal whose impurity concentration is segregated with C expressed by the above-mentioned α-temperature formula are obtained.
坩堝として内径: 150mmの石英坩堝を、また原料
として多結晶シリコンを用い、不純物としてシリコンに
対する偏析係数ke = 0.35のリンをmい、直径
5011llmの第1のシリコン単結晶の無偏析引上げ
を1回行った。A quartz crucible with an inner diameter of 150 mm was used as a crucible, polycrystalline silicon was used as a raw material, phosphorus with a segregation coefficient ke = 0.35 for silicon was added as an impurity, and a first silicon single crystal with a diameter of 5011 llm was pulled without segregation. I went there once.
なお坩堝の回転数0.5rpm 引上軸の回転数15rpm(坩堝と反対)である。The rotation speed of the crucible is 0.5 rpm. The rotation speed of the pulling shaft was 15 rpm (opposite to the crucible).
次いで残留固体層Pを溶融した後、溶融液層中の不純物
濃度を第1の単結晶引上げ過程中における溶融液層の不
純物濃度と同じに設定し、CZ法により第2の単結晶の
引上げ、引上げたシリコン単結晶の結晶引上げ率fs”
0.1〜0.9の各部位における抵抗率の分布を測定し
た。その結果は第3図に示す如くである.
第3図は横軸にf3を、また縦軸に抵抗率ρ/ρ。〔−
〕をとって示してある。グラフ中O印でプロットしてあ
るのは第1の単結晶についての、また●印でプロットし
てあるのは第2の単結晶についての結果である。Next, after melting the remaining solid layer P, the impurity concentration in the melt layer is set to be the same as the impurity concentration in the melt layer during the first single crystal pulling process, and the second single crystal is pulled by the CZ method, Crystal pulling rate fs of pulled silicon single crystal
The distribution of resistivity at each site of 0.1 to 0.9 was measured. The results are shown in Figure 3. In Figure 3, the horizontal axis represents f3, and the vertical axis represents resistivity ρ/ρ. [-
] is shown. In the graph, the results plotted with O marks are the results for the first single crystal, and the results plotted with ● marks are the results for the second single crystal.
このグラフから明らかなように第1の単結晶については
略無偏析、換言すれば抵抗率の変わらない結晶を引上げ
得ていることが解る。As is clear from this graph, it can be seen that the first single crystal can be pulled with almost no segregation, in other words, with no change in resistivity.
なお、第2の単結晶についても所定の不純物濃度分布.
換言すれば勾配を有する抵抗率の単結晶が得られている
ことが解る。Note that the second single crystal also has a predetermined impurity concentration distribution.
In other words, it can be seen that a single crystal with resistivity having a gradient is obtained.
また、上述した実施例では溶融層法,CZ法により各1
本の単結晶を引上げた場合について説明したが、溶融層
法では単結晶を引上げる都度,固体原料を供給して、無
偏析の2本以上の単結晶を引上げ、最後にCZ法を適用
して所定の不純物濃度分布を有する単結晶の引上げを行
ってもよいことば勿論である。In addition, in the above-mentioned embodiment, each of the molten layer method and CZ method was used.
We have explained the case of pulling a single crystal in this book, but in the fused layer method, each time a single crystal is pulled, a solid raw material is supplied, two or more single crystals without segregation are pulled, and finally the CZ method is applied. Of course, a single crystal having a predetermined impurity concentration distribution may also be pulled.
(効果〕
以上の如く本発明方法にあっては溶融層法とCZ法とを
組み合せることによって歩留りよく結晶を引上げること
が可能となり、作業効率がよ《、また設備コスト、熱源
の有効利用が図れ、製造歩留りが大幅に向上するなど本
発明は優れた効果を奏するものである。(Effects) As described above, in the method of the present invention, by combining the fused layer method and the CZ method, it is possible to pull crystals with a high yield, improving work efficiency, and reducing equipment costs and effective use of heat sources. The present invention exhibits excellent effects, such as a significant improvement in manufacturing yield.
第1図は本発明方法の実施状態を示す結晶成長装置の模
式的縦断面図、第2図は坩堝内のチャージ材料の相変化
の推移を示す説明図、第3図は本発明方法で得た単結晶
についてのf,と抵抗率との関係を示すグラフ、第4,
5図はチョクラルスキー法.溶融層法の各説明図、第6
図は一般的な溶融層法におけるチャージ材料の相変化の
推移を示す説明図、第7図は溶融層法における坩堝の温
度制御の例を示す説明図である。
1・・・チャンバ 2・・・坩堝 3・・・嶌一タ4・
・・シャッタ 5・・・プルチャンバ 6・・・引上軸
7・・・種結晶 8・・・単結晶 11・・・固体原料
供給器特 許 出願人 住友金属工業株式会社代理人
弁理士 河 野 登 夫見
!
’ts
箋
I
算
!
苑
面
捧
肥
嶌
I
{イ)
(口)
第
【FIG. 1 is a schematic vertical cross-sectional view of a crystal growth apparatus showing the implementation state of the method of the present invention, FIG. 2 is an explanatory diagram showing the transition of phase change of the charge material in the crucible, and FIG. Graph showing the relationship between f and resistivity for a single crystal, 4th,
Figure 5 shows the Czochralski method. Explanatory diagrams of the fused layer method, No. 6
The figure is an explanatory diagram showing the transition of the phase change of the charge material in a general fused bed method, and FIG. 7 is an explanatory diagram showing an example of crucible temperature control in the fused bed method. 1... Chamber 2... Crucible 3... Shimaichita 4.
...Shutter 5...Pull chamber 6...Pulling shaft 7...Seed crystal 8...Single crystal 11...Solid raw material supply device patent Applicant: Sumitomo Metal Industries Co., Ltd. Agent
Patent attorney Noboru Kono! 'ts paper calculation! En-men dedicated Hishima I {i) (mouth) No.
Claims (1)
液層下に位置するこれと略同質の固体層とを共存させた
状態で溶融液層厚さを制御しつつ前記溶融液層から一の
結晶を引上げ、前記固体層がその層厚さの減少により溶
融 液層内に浮遊するに先立って前記一の結晶の引上げを終
了する過程と、坩堝内に残留する固体層を全て溶融する
過程と、この過程と同時又はその前後で引上げた一の結
晶を、チャンバ外へ取り出す過程と、固体層を全て溶融
せしめた状態の溶融液層から他の結晶を引上げる過程と
を含むことを特徴とする結晶成長方法。 2、固体層を全て溶融せしめた状態の溶融液層に不純物
を添加する過程を含む請求項1記載の結晶成長方法。[Claims] 1. In a crucible placed in a chamber, a molten liquid layer and a solid layer of substantially the same quality as the molten liquid layer located below the molten liquid layer coexist, and the thickness of the molten liquid layer is determined. pulling a crystal from the melt layer in a controlled manner and finishing the pulling of the crystal before the solid layer becomes suspended in the melt layer due to a decrease in the layer thickness; A process of melting all the remaining solid layer, a process of taking one crystal pulled out of the chamber at the same time or before or after this process, and removing other crystals from the molten liquid layer in a state where all the solid layer has been melted. A crystal growth method characterized by comprising a pulling process. 2. The crystal growth method according to claim 1, which includes the step of adding impurities to the molten liquid layer in a state where the solid layer is completely melted.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5578189A JPH02233581A (en) | 1989-03-07 | 1989-03-07 | Crystal growth |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5578189A JPH02233581A (en) | 1989-03-07 | 1989-03-07 | Crystal growth |
Publications (1)
Publication Number | Publication Date |
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JPH02233581A true JPH02233581A (en) | 1990-09-17 |
Family
ID=13008439
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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JP5578189A Pending JPH02233581A (en) | 1989-03-07 | 1989-03-07 | Crystal growth |
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JP (1) | JPH02233581A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04144990A (en) * | 1990-10-05 | 1992-05-19 | Osaka Titanium Co Ltd | Growth of crystal |
JPH0532480A (en) * | 1991-02-20 | 1993-02-09 | Sumitomo Metal Ind Ltd | Method for growing crystal |
JPH06263583A (en) * | 1993-03-15 | 1994-09-20 | Sumitomo Sitix Corp | Crystal growing method |
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Publication number | Priority date | Publication date | Assignee | Title |
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JPS61215285A (en) * | 1985-03-20 | 1986-09-25 | Sumitomo Metal Ind Ltd | Method of growing crystal |
JPS63252989A (en) * | 1987-04-08 | 1988-10-20 | Sumitomo Electric Ind Ltd | Production of semiconductor single crystal by pull-up method |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61215285A (en) * | 1985-03-20 | 1986-09-25 | Sumitomo Metal Ind Ltd | Method of growing crystal |
JPS63252989A (en) * | 1987-04-08 | 1988-10-20 | Sumitomo Electric Ind Ltd | Production of semiconductor single crystal by pull-up method |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04144990A (en) * | 1990-10-05 | 1992-05-19 | Osaka Titanium Co Ltd | Growth of crystal |
JPH0532480A (en) * | 1991-02-20 | 1993-02-09 | Sumitomo Metal Ind Ltd | Method for growing crystal |
JPH06263583A (en) * | 1993-03-15 | 1994-09-20 | Sumitomo Sitix Corp | Crystal growing method |
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