JP2003342730A - Method of depositing pzt thin film by chemical vapor growth method - Google Patents

Method of depositing pzt thin film by chemical vapor growth method

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Publication number
JP2003342730A
JP2003342730A JP2002182207A JP2002182207A JP2003342730A JP 2003342730 A JP2003342730 A JP 2003342730A JP 2002182207 A JP2002182207 A JP 2002182207A JP 2002182207 A JP2002182207 A JP 2002182207A JP 2003342730 A JP2003342730 A JP 2003342730A
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JP
Japan
Prior art keywords
otbu
thin film
film
pzt thin
vaporizer
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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JP2002182207A
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Japanese (ja)
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JP3969206B2 (en
Inventor
Hidekimi Kadokura
秀公 門倉
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Kojundo Kagaku Kenkyusho KK
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Kojundo Kagaku Kenkyusho KK
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a raw material system, a feed system and a film deposition method by which a process window wherein a film composition Pb/(Zr+Ti)=1 is opened, and the Zr/Ti ratio can fixedly be held to a prescribed value in CVD (chemical vapor deposition) by a system using a liquid mass flow controller and a carburettor effective for the mass production of a PZT (PbZrO<SB>3</SB>-PbTiO<SB>3</SB>) film, and to deposit the film even at a low temperature of ≤500°C. <P>SOLUTION: A cyclohexane solution of Pb(dpm)<SB>2</SB>in a high concentration is fed from a raw material vessel 1 to a carburettor 1 through a mass flow controller 1. A crude mixed liquid of Zr(OtBu)<SB>4</SB>and Ti(OtBu)<SB>4</SB>is fed from a raw material vessel 2 to a carburettor 2 through a mass flow controller 2. These gases and gaseous O<SB>2</SB>are mixed with a shower head and are introduced into the surface of a Pt/SiO<SB>2</SB>/Si substrate, and CVD is carried out under 1 Torr at 480°C to deposit a satisfactory PZT film. <P>COPYRIGHT: (C)2004,JPO

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【発明の属する技術分野】本発明は、化学気相成長法
(以下CVD法と表す)により、PZT、PLZT薄膜
を製造する方法に関する。
TECHNICAL FIELD The present invention relates to a method for producing a PZT or PLZT thin film by a chemical vapor deposition method (hereinafter referred to as a CVD method).

【0002】[0002]

【従来の技術】高集積の不揮発性メモリーや圧電素子な
どに用いられるPbZr1−yTi(0<y<
1、以下PZTと表す)や、(Pb1−x,La
(Zr1−y,Ti)O(0<x<1,0<y<
1)(以下PLZTと表す)薄膜を量産性よく製造する
方法として、CVD法が用いられる。その原料供給方式
には、Pb,Zr,TiおよびLaの各化合物をそのま
ま気化して供給する方式と溶液にして気化供給する方式
があるが、後者のほうが量産に向いている。
2. Description of the Related Art PbZr 1-y Ti y O 3 (0 <y <, which is used for a highly integrated nonvolatile memory, a piezoelectric element, or the like.
1, hereinafter referred to as PZT), or (Pb 1-x , La x ).
(Zr 1-y , Ti y ) O 3 (0 <x <1, 0 <y <
1) The CVD method is used as a method for producing a thin film (hereinafter referred to as PLZT) with high mass productivity. As the raw material supply method, there are a method of vaporizing and supplying each compound of Pb, Zr, Ti and La as they are and a method of vaporizing and supplying them as a solution, and the latter is more suitable for mass production.

【0003】Pb(dpm),Zr(OtBu)
Ti(OiPr)の各化合物をそのまま気化して供給
する前者の方式のCVDでは膜組成がPb/(Zr+T
i)=1と自律的になるPb供給のプロセスウィンドウ
が広く開くことがM.Aratani et al,J
pn.J.Appl.Phys.Vol.40,412
6(2001)などに開示されている。ここでプロセス
ウィンドウとは、膜組成Pb/(Zr+Ti)=1.0
となる原料供給速度およびその比率の領域をいう。例え
ば、(Zr+Ti)原料に対するPb原料の供給比が変
化しても膜組成Pb/(Zr+Ti)=1.0が維持さ
れる供給比の範囲をいう。Pb/(Zr+Ti)が1.
0からずれると、強誘電性の特性が低下するので、プロ
セスウィンドウが広く開かないと量産プロセスとしては
採用し難い。しかし溶液気化法ではCVDの際に大量の
溶媒が存在するためか、CVD速度が低下すること、プ
ロセスウィンドウがほとんどないことの問題点があるこ
とがわかってきた。
Pb (dpm) 2 , Zr (OtBu) 4 ,
In the former type of CVD in which each compound of Ti (OiPr) 4 is directly vaporized and supplied, the film composition is Pb / (Zr + T
i) = 1, the process window of Pb supply becomes autonomous and becomes wide. Aratani et al, J
pn. J. Appl. Phys. Vol. 40,412
6 (2001) and the like. Here, the process window is the film composition Pb / (Zr + Ti) = 1.0.
The area of the raw material supply rate and its ratio. For example, it means the range of the supply ratio in which the film composition Pb / (Zr + Ti) = 1.0 is maintained even if the supply ratio of the Pb raw material to the (Zr + Ti) raw material changes. Pb / (Zr + Ti) is 1.
If it deviates from 0, the ferroelectric characteristics deteriorate, so it is difficult to adopt it as a mass production process unless the process window is wide. However, it has been found that the solution vaporization method has problems that the CVD rate is lowered and that there is almost no process window, probably because a large amount of solvent is present during CVD.

【0004】この問題点に関しては、尾関ら、第49回
応用物理学会講演予稿集p511(2002.3)が、
Pb(dpm)/オクタン(0.1mol/l)、Z
r(OtBu)/オクタン(0.1mol/l)、T
i(OiPr)/オクタン(0.1mol/l)を用
いた溶液気化方式で、500、600℃のCVDを行っ
た結果、堆積量が減少し、プロセスウィンドウがないこ
とを報告している。M.Miyake et al,J
pn.J.Appl.Phys.Vol.41,241
(2002)は、Pb(dpm)/THF(0.05
mol/l)、Zr(dibm)/THF(0.1m
ol/l)、Ti(OiPr)(dpm)/THF
(0.1mol/l)を用いた溶液気化方式で、20T
orr、550℃のCVDを行ったが、プロセスウィン
ドウの存在は記していない。王谷ら、第49回応用物理
学会講演予稿集p511(2002.3)は、[Pb
(methd)+Zr(methd)+Ti(mp
d)(methd)]/エチルシクロヘキサン(0.
049,0.03,0.03mol/l)を用いた溶液
気化方式で、3Torr、550℃基板温度のCVDを
行った結果、膜のPb組成が溶液のPb濃度に敏感に影
響されプロセスウィンドウが開かなかったことを発表し
ている。ここでmethdは[1−(2−メトキシ)エ
トキシ−2,2,6,6−テトラメチル−3,5−ヘプ
タンジオナート]、mpdは[2−メチル−2,4−ペ
ンタンジオキシ]を表す。Y.−S.Park,Int
egrated Ferroelectrics,Vo
l.39,231(2001)は、Pb(dpm)
ヘプタン(0.05mol/l)、Zr(OiPr)
(dpm)/ヘプタン(0.05mol/l)、Ti
(OiPr)(dpm)/ヘプタン(0.05mo
l/l)を用いた溶液気化方式で、480〜570℃の
CVDを行った結果、プロセスウィンドウが開かなかっ
たことを開示している。
Regarding this problem, Ozeki et al., Proc. Of the 49th Japan Society of Applied Physics p511 (2002. 3)
Pb (dpm) 2 / octane (0.1 mol / l), Z
r (OtBu) 4 / octane (0.1 mol / l), T
It has been reported that as a result of performing CVD at 500 and 600 ° C. by a solution vaporization method using i (OiPr) 4 / octane (0.1 mol / l), the deposition amount is reduced and there is no process window. M. Miyake et al, J
pn. J. Appl. Phys. Vol. 41,241
(2002) is Pb (dpm) 2 /THF(0.05
mol / l), Zr (dibm) 4 / THF (0.1 m
ol / l), Ti (OiPr) 2 (dpm) 2 / THF
Solution vaporization method using (0.1 mol / l), 20T
Although the CVD was performed at orr and 550 ° C., the existence of the process window is not shown. Otani et al., Proceedings of the 49th Japan Society of Applied Physics p511 (2002.3) is [Pb
(Methd) 2 + Zr (methd) 4 + Ti (mp
d) (methd) 2 ] / ethylcyclohexane (0.
049, 0.03, 0.03 mol / l), a solution vaporization method was used, and as a result of performing CVD at a substrate temperature of 3 Torr and 550 ° C., the Pb composition of the film was sensitively affected by the Pb concentration of the solution and the process window was It has announced that it did not open. Here, methd is [1- (2-methoxy) ethoxy-2,2,6,6-tetramethyl-3,5-heptanedionate] and mpd is [2-methyl-2,4-pentanedioxy]. Represent Y. -S. Park, Int
Egged Ferroelectrics, Vo
l. 39,231 (2001) is Pb (dpm) 2 /
Heptane (0.05 mol / l), Zr (OiPr) 2
(Dpm) 2 / heptane (0.05 mol / l), Ti
(OiPr) 2 (dpm) 2 / heptane (0.05mo
It is disclosed that the process window did not open as a result of performing the CVD at 480 to 570 ° C. by the solution vaporization method using 1 / l).

【0005】以上述べたように、溶液気化方式のCVD
でPZT膜を製造する方法において、プロセスウィンド
ウが開いたという報告は未だない。
As described above, solution vaporization type CVD
There is no report that a process window has been opened in the method of manufacturing a PZT film by.

【0006】また溶液気化方式に用いられているZr原
料はZr(dpm),Zr(OiPr)(dpm)
,Zr(OiPr)(dpm),Zr(dibm)
,Zr(methd)などであるが、CVDでの膜
へのZrの取り込みが不安定であるという問題点がある
ことがわかってきた。PZT膜のZr/Ti比は、PZ
T膜の結晶型を決め、強誘電特性を決めるので、所定の
値に制御する必要がある。Zrの取り込みが不安定であ
ると、Zr/Ti比がふれることになり問題であった。
Zr raw materials used in the solution vaporization system are Zr (dpm) 4 and Zr (OiPr) 2 (dpm).
2 , Zr (OiPr) (dpm) 3 , Zr (dibm)
4 , Zr (methd) 4, etc., but it has been found that there is a problem that the incorporation of Zr into the film by CVD is unstable. The Zr / Ti ratio of the PZT film is PZ
Since the crystal type of the T film is determined and the ferroelectric property is determined, it is necessary to control it to a predetermined value. If the Zr uptake is unstable, the Zr / Ti ratio may fluctuate, which is a problem.

【0007】Al配線が耐える温度以下でPZTの不揮
発性メモリーを作れば、高集積化され、多層メタル化さ
れた半導体装置ができるので、500℃以下、好ましく
は450℃以下の基板温度で薄膜を製造する方法が特開
2000−58526号などで開示されている。しかし
この実施例は溶液気化方式ではなく、全く溶媒を使って
いない方式である。
If a non-volatile memory of PZT is manufactured at a temperature lower than the Al wiring can withstand, a highly integrated semiconductor device having a multi-layer metal structure can be obtained. The manufacturing method is disclosed in Japanese Patent Laid-Open No. 2000-58526. However, this embodiment is not a solution vaporization system but a system that does not use a solvent at all.

【0008】Zr(OtBu)やTi(OiPr)
の液体原料はバブリング供給するより液体マスフローコ
ントローラーと気化器で気化供給するほうが、大量のガ
スを送れるので量産には好ましい。生の液体アルコキシ
ドを液体マスフローコントローラーと気化器で気化供給
する方式はSi(OEt)やTa(OEt)で工業
化されている。しかしZr(OtBu)とTi(Oi
Pr)の比を精度良く所定の値に維持するには、それ
らの供給量をそれぞれの液体マスフローコントローラー
で高い精度で制御することが必要であるが、これは容易
ではない。二つの液体マスフローコントローラーを使う
代わりに、一つの原料容器中でZr(OtBu)とT
i(OiPr)と所定の比率で混合しておけば良いの
であるが、液体で混合すると瞬時にアルコキシル基の交
換が起こり、析出物が生成するので、この方法は使えな
い。
Zr (OtBu) 4 and Ti (OiPr) 4
It is preferable to mass-produce the liquid raw material by vaporizing and supplying it with a liquid mass flow controller and a vaporizer rather than bubbling it, because a large amount of gas can be sent. A method of vaporizing and supplying raw liquid alkoxide with a liquid mass flow controller and a vaporizer has been industrialized with Si (OEt) 4 and Ta (OEt) 5 . However, Zr (OtBu) 4 and Ti (Oi
In order to maintain the ratio of Pr) 4 at a predetermined value with high accuracy, it is necessary to control the supply amounts thereof with high accuracy by the respective liquid mass flow controllers, but this is not easy. Instead of using two liquid mass flow controllers, Zr (OtBu) 4 and T
It may be mixed with i (OiPr) 4 in a predetermined ratio, but when mixed with a liquid, the alkoxyl group is exchanged instantly and a precipitate is formed, so this method cannot be used.

【0009】[0009]

【発明が解決しようとする課題】本発明の目的は、PZ
T膜の量産には液体マスフローコントローラーと気化器
を使った方式が好ましいので、それを容易にできる原料
系と供給系を提供することである。またその方法におい
て、できるだけ溶媒量をへらしてプロセスウィンドウが
開きやすくし、Zr/Ti比が所定の値に維持でき、5
00℃以下の低温でも成膜できる方法を提供することで
ある。
The object of the present invention is to provide a PZ
Since a method using a liquid mass flow controller and a vaporizer is preferable for mass production of T film, it is an object to provide a raw material system and a supply system capable of facilitating the method. Further, in that method, the amount of solvent is reduced as much as possible so that the process window can be easily opened, and the Zr / Ti ratio can be maintained at a predetermined value.
It is to provide a method capable of forming a film even at a low temperature of 00 ° C. or less.

【0010】[0010]

【課題を解決するための手段】本発明者は、Pb(dp
m)だけを溶液にし、他のZrとTi原料は、生の揮
発性の高いアルコキシドを使うこと、Ti源として、Z
r(OtBu)と反応しないTi(OtBu)を使
えば、一つの原料容器中に所定のZr/Ti比の混合液
ができること、Pb(dpm)溶液を気化器1で気化
させ、Zr(OtBu)とTi(OtBu)混合液
を気化器2で気化させ、そのあとガスで合わせれば、不
都合な反応が起こらなくCVDが行え、プロセスウィン
ドウが開くことを見出し、本発明を完成するに至った。
The present inventor has found that Pb (dp
m) Only 2 is used as a solution, and the other Zr and Ti raw materials are raw volatile alkoxides.
If Ti (OtBu) 4 that does not react with r (OtBu) 4 is used, a mixed solution having a predetermined Zr / Ti ratio can be formed in one raw material container, and a Pb (dpm) 2 solution is vaporized by a vaporizer 1 to produce Zr. The inventors have found that if a mixture of (OtBu) 4 and Ti (OtBu) 4 is vaporized in a vaporizer 2 and then combined with a gas, CVD can be carried out without causing an inconvenient reaction and a process window can be opened, thereby completing the present invention. Came to.

【0011】本発明は、化学気相成長法によりPZT薄
膜を製造する方法において、ビス(β−ジケトナート)
鉛溶液とZr(OtBu)とTi(OtBu)と酸
化剤を原料として用いることを特徴とするPZT薄膜の
製法である。
The present invention provides a method for producing a PZT thin film by a chemical vapor deposition method, which comprises bis (β-diketonate).
A method for producing a PZT thin film is characterized in that a lead solution, Zr (OtBu) 4 , Ti (OtBu) 4, and an oxidizing agent are used as raw materials.

【0012】本発明は、化学気相成長法によりPZT薄
膜を製造する方法において、Pb(dpm)溶液とZ
r(OtBu)とTi(OtBu)と酸化剤を原料
として用いることを特徴とするPZT薄膜の製法であ
る。
The present invention relates to a method for producing a PZT thin film by a chemical vapor deposition method, wherein a Pb (dpm) 2 solution and Z are used.
This is a method for producing a PZT thin film, which uses r (OtBu) 4 , Ti (OtBu) 4, and an oxidant as raw materials.

【0013】本発明は、ビス(β−ジケトナート)鉛溶
液を気化器1で気化させ、Zr(OtBu)とTi
(OtBu)との混合液を気化器2で気化させ、これ
ら2つの気化器からのガスと酸化剤を混合しCVD室に
導入することを特徴とするPZT薄膜の製法である。
In the present invention, a bis (β-diketonate) lead solution is vaporized by a vaporizer 1 to obtain Zr (OtBu) 4 and Ti.
This is a method for producing a PZT thin film, characterized in that a mixed liquid with (OtBu) 4 is vaporized by a vaporizer 2 and the gas from these two vaporizers and an oxidant are mixed and introduced into a CVD chamber.

【0014】本発明は、ビス(β−ジケトナート)鉛溶
液を気化器1で気化させ、1つの原料容器から供給され
たZr(OtBu)とTi(OtBu)との所定比
率の混合液を気化器2で気化させ、これら2つの気化器
からのガスと酸化剤を混合しCVD室に導入することを
特徴とするPZT薄膜の製法である。
In the present invention, a bis (β-diketonate) lead solution is vaporized in a vaporizer 1 and a mixed liquid of Zr (OtBu) 4 and Ti (OtBu) 4 supplied from one raw material container at a predetermined ratio is prepared. This is a method for producing a PZT thin film, which is characterized in that the vaporizer 2 vaporizes, the gas from these two vaporizers and the oxidant are mixed and introduced into a CVD chamber.

【0015】本発明は、基板温度が400〜500℃で
あることを特徴とする上記記載のPZT薄膜の製法であ
る。
The present invention is the method for producing a PZT thin film described above, characterized in that the substrate temperature is 400 to 500 ° C.

【0016】本発明は、ビス(β−ジケトナート)鉛溶
液の溶媒がTHF、トルエン、酢酸ブチル、シクロヘキ
サン、メチルシクロヘキサン、エチルシクロヘキサンの
群から選ばれた1種であることを特徴とする上記記載の
PZT薄膜の製法である。
The present invention is characterized in that the solvent of the bis (β-diketonate) lead solution is one selected from the group consisting of THF, toluene, butyl acetate, cyclohexane, methylcyclohexane and ethylcyclohexane. This is a method for manufacturing a PZT thin film.

【0017】本発明は、PZT薄膜のPbを一部Laで
置換した上記記載のPLZT薄膜の製法である。
The present invention is a method for producing the PLZT thin film described above, wherein Pb of the PZT thin film is partially replaced with La.

【0018】[0018]

【発明の実施の形態】本発明に用いられるビス(β−ジ
ケトナート)鉛としては、Pb(dpm)、[ビス
(2,2,6,6−テトラメチル−3,5−オクタンジ
オナート)鉛]、ビス(2,2,6−トリメチル−3,
5−ヘプタンジオナート)鉛、ビス(6−エチル−2,
2−ジメチル−3,5−オクタンジオナート)鉛、Pb
(methd)などである。好ましくは、容易に入手
でき最も熱安定性の高いPb(dpm)である。
BEST MODE FOR CARRYING OUT THE INVENTION As bis (β-diketonato) lead used in the present invention, Pb (dpm) 2 , [bis (2,2,6,6-tetramethyl-3,5-octanedionate)] Lead], bis (2,2,6-trimethyl-3,
5-heptanedionato) lead, bis (6-ethyl-2,
2-Dimethyl-3,5-octanedionate) Lead, Pb
(Methd) 2 and the like. Pb (dpm) 2 which is easily available and has the highest thermal stability is preferable.

【0019】CVD室に入る溶媒量をできるだけ少なく
するために、本発明に用いられるビス(β−ジケトナー
ト)鉛溶液の溶媒としては、高い溶解能を有し、Zr
(OtBu)やTi(OtBu)と反応しにくいも
のであることが必要である。これらの要求に合うものと
して、THF、トルエン、酢酸ブチル、シクロヘキサ
ン、メチルシクロヘキサン、エチルシクロヘキサンが挙
げられる。種々の溶媒1Lに室温で溶解するPb(dp
m)の質量(単位g)を表1に示す。
In order to reduce the amount of the solvent entering the CVD chamber as much as possible, the solvent of the bis (β-diketonate) lead solution used in the present invention has a high dissolving ability and Zr.
It is necessary that it is difficult to react with (OtBu) 4 or Ti (OtBu) 4 . Those which meet these requirements include THF, toluene, butyl acetate, cyclohexane, methylcyclohexane and ethylcyclohexane. Pb (dp dissolved in 1 L of various solvents at room temperature
Table 1 shows the mass of m) 2 (unit: g).

【0020】[0020]

【表1】 [Table 1]

【0021】溶媒量をできるだけ減らすには、Pb(d
pm)の溶解能の高い溶媒を使い、気化器圧力をでき
るだけ低くし、気化器温度をできるだけ高くすること
が、望ましい。しかしPb(dpm)の低い蒸気圧と
熱安定性を考慮すると、およそ200〜250℃の範囲
である。
In order to reduce the amount of solvent as much as possible, Pb (d
It is desirable to use a solvent with a high solubility of pm) 2 and to keep the vaporizer pressure as low as possible and the vaporizer temperature as high as possible. However, considering the low vapor pressure and thermal stability of Pb (dpm) 2 , it is in the range of about 200 to 250 ° C.

【0022】Pb(dpm)の飽和蒸気圧は、本発明
者が気体飽和法により130〜170℃で測定した結
果、次のクラウジウス−クラペイロン式で表される。 Log10P=−4480/T+9.94 (P:
Torr、T:K) またAr1気圧でのPb(dpm)の沸点をTG−D
TAで調べると350〜359℃であった。これは蒸気
圧式の外挿から求めた値361℃と良く一致しているの
で、式の外挿は、信頼できる。そこでPb(dpm)
の飽和蒸気圧を、上式から求めると、3.0Torr/
200℃、24Torr/250℃となる。
The saturated vapor pressure of Pb (dpm) 2 is expressed by the following Clausius-Clapeyron equation as a result of the measurement by the present inventor at 130 to 170 ° C. by the gas saturation method. Log 10 P = −4480 / T + 9.94 (P:
Torr, T: K) Also, the boiling point of Pb (dpm) 2 at 1 atmosphere of Ar is TG-D.
When examined by TA, it was 350 to 359 ° C. This is in good agreement with the value 361 ° C. obtained from the extrapolation of the vapor pressure formula, so the extrapolation of the formula is reliable. Then Pb (dpm) 2
When the saturated vapor pressure of is calculated from the above equation, it is 3.0 Torr /
It becomes 200 degrees Celsius and 24 Torr / 250 degrees Celsius.

【0023】気化器中の気体温度が完全に気化器温度に
なっていれば、200℃の気化器圧力10Torrとし
た場合、(10−3.0=)7.0Torr分の溶媒が
あれば、原理上は全量が気体となりうる。すなわち最小
必要溶媒量は、Pb(dpm)の(7.0/3.0
=)2.4倍mol量である。表1の溶媒の分子量はT
HFの72から酢酸ブチルの116の間にあるので簡単
のため、分子量100、密度0.8g/cmで代表さ
せる。Pb(dpm)1molと溶媒2.4molの
混合物の容積は、およそ Pb(dpm)分+溶媒分=(574/1.52)+
(240/0.8)=378+300=678ml である。すなわちPb(dpm)濃度は1/0.67
8=1.47mol/lとなる。これは平衡状態の場合
であり、実際には達成されないので、より多くの溶媒と
より高い気化器温度が必要となる。
If the gas temperature in the vaporizer is completely equal to the vaporizer temperature, and if the vaporizer pressure at 200 ° C. is 10 Torr, (10-3.0 =) 7.0 Torr of solvent is available. In principle, the whole amount can be gas. That is, the minimum required amount of solvent is (7.0 / 3.0) of Pb (dpm) 2.
=) 2.4 times the molar amount. The molecular weight of the solvents in Table 1 is T
Since it is between 72 of HF and 116 of butyl acetate, it is represented by a molecular weight of 100 and a density of 0.8 g / cm 3 for simplicity. The volume of the mixture of 1 mol of Pb (dpm) 2 and 2.4 mol of the solvent is about Pb (dpm) 2 min + solvent = (574 / 1.52) +
(240 / 0.8) = 378 + 300 = 678 ml. That is, the Pb (dpm) 2 concentration is 1 / 0.67
8 = 1.47 mol / l. This is the equilibrium case and is not achieved in practice, thus requiring more solvent and higher vaporizer temperature.

【0024】以上のことから、Pb(dpm)1mo
l/l溶液は、気化器圧力10Torr、気化器温度2
50℃程度で気化できると考えられる。He,Ar,N
などのイナートガスが共存すれば、より低い気化器温
度で気化できる。また気化器圧力が5Torrと低けれ
ば、より低い気化器温度で気化できる。もちろん気化器
の構造や使用方法で、詰まりや溶媒の先飛びを起こさな
い工夫は必要である。表1のTHF、トルエン、酢酸n
−ブチル、シクロヘキサン、メチルシクロヘキサンであ
ればPb(dpm)0.5mol/l程度の溶液にで
きるので好都合である。
From the above, Pb (dpm) 2 1mo
The l / l solution has a vaporizer pressure of 10 Torr and a vaporizer temperature of 2
It is considered that vaporization is possible at about 50 ° C. He, Ar, N
If an inert gas such as 2 coexists, it can be vaporized at a lower vaporizer temperature. If the vaporizer pressure is as low as 5 Torr, vaporization can be performed at a lower vaporizer temperature. Of course, it is necessary to devise the structure and usage of the vaporizer so as not to cause clogging and skipping of the solvent. THF, toluene, acetic acid n in Table 1
-Butyl, cyclohexane, and methylcyclohexane are convenient because a solution of about 0.5 mol / l Pb (dpm) 2 can be formed.

【0025】Ti(OtBu)は、融点4℃の室温で
液体の化合物で、その物性はZr(OtBu)に非常
によく似ている。それぞれの物性を表2に記す。
Ti (OtBu) 4 is a compound which is liquid at room temperature and has a melting point of 4 ° C., and its physical properties are very similar to those of Zr (OtBu) 4 . The physical properties of each are shown in Table 2.

【0026】[0026]

【表2】 [Table 2]

【0027】どちらも単量体であり、混合した場合、混
じり合うだけで、会合することはない。物性も似ている
ので、完全に均一な混合液ができる。気化器直前の配管
で混合しても、原料容器中で混合しても全く問題は起き
ない。また水分や酸素がなければ、気化器温度150℃
でも熱分解することはない。
Both are monomers, and when they are mixed, they only mix with each other and do not associate with each other. Since the physical properties are similar, a completely uniform mixture can be obtained. There is no problem at all even if mixed in the pipe just before the vaporizer or mixed in the raw material container. If there is no water or oxygen, the vaporizer temperature is 150 ° C.
But it does not pyrolyze.

【0028】Zr(OtBu)とTi(OtBu)
とは、一つの原料容器中で所定の比で混合したものを使
うのが好ましい。そうすれば、ZrとTiの混合均一性
が良く、マスフローコントローラーが1基でよく、その
フロー制御の精度も少し低くても良いという利点があ
る。Zr(OtBu)とTi(OtBu)との混合
比は、膜組成、成膜温度、Pb(dpm)の共存など
に影響されるので、あらかじめ実験により、求めておけ
ばよい。
Zr (OtBu) 4 and Ti (OtBu) 4
It is preferable to use a mixture of the materials in one raw material container at a predetermined ratio. Then, there is an advantage that the mixing uniformity of Zr and Ti is good, the mass flow controller is one, and the accuracy of the flow control may be slightly low. The mixing ratio of Zr (OtBu) 4 and Ti (OtBu) 4 is influenced by the film composition, the film forming temperature, the coexistence of Pb (dpm) 2 , and the like, and may be determined in advance by experiments.

【0029】PbTiOの下地層を形成後、PZTを
成膜する場合には、上記Zr(OtBu)とTi(O
tBu)との混合物の入った原料容器Aと、Ti(O
tBu)の入った原料容器Bを、セットして使った方
がよい。これであれば、マスフローコトローラーは、1
基でもよく、かつ、B使用の場合でも、A使用の場合で
も、その精度は少し低くてもよい。しかし、Zr(Ot
Bu)の入った原料容器CとTi(OtBu)の入
った原料容器Bがセットされた場合、PZT成膜時には
二つのマスフローコントローラーは高い精度が求められ
る。これは工業上避けるべきである。
When PZT is formed after forming an underlayer of PbTiO 3 , Zr (OtBu) 4 and Ti (O
raw material container A containing a mixture with tBu) 4 and Ti (O
It is better to set and use the raw material container B containing tBu) 4 . In this case, the mass flow controller is 1
The base may be used, and the accuracy may be a little low when using B or when using A. However, Zr (Ot
When the raw material container C containing Bu) 4 and the raw material container B containing Ti (OtBu) 4 are set, the two mass flow controllers are required to have high accuracy during PZT film formation. This should be avoided industrially.

【0030】本発明では、PZT成膜の基板温度を40
0〜500℃とできる。Pb,Zr,Ti源が共に低温
堆積可能な化合物であるので、このような低温でも良好
な強誘電性を示す膜が得られる。
In the present invention, the substrate temperature for PZT film formation is set to 40.
It can be 0 to 500 ° C. Since the Pb, Zr, and Ti sources are all compounds that can be deposited at a low temperature, a film exhibiting good ferroelectricity even at such a low temperature can be obtained.

【0031】CVD室の圧力は、0.001〜10To
rrである。好ましくは、0.01〜3Torrであ
る。圧力が3Torrより高いと、気化器圧力が10T
orr程度に高くならざるを得ない。その結果、Pb
(dpm)が気化しにくくなるので、濃度を下げ、多
くの溶媒を使ったり、多くのキャリヤーガスを使った
り、より高温にせざるを得なくなる。高濃度の溶媒が存
在すると、Pb/(Zr+Ti)=1のプロセスウィン
ドウが狭くなる。これらの欠点を除くためには、できる
だけ低圧が好ましいが、あまり低くなると、成膜速度が
低下する。
The pressure in the CVD chamber is 0.001-10To.
rr. It is preferably 0.01 to 3 Torr. If the pressure is higher than 3 Torr, the vaporizer pressure will be 10T.
Inevitably it will be as high as orr. As a result, Pb
Since (dpm) 2 is less likely to be vaporized, the concentration must be lowered to use a large amount of solvent, a large amount of carrier gas, and a higher temperature. The presence of high concentrations of solvent narrows the process window for Pb / (Zr + Ti) = 1. In order to eliminate these drawbacks, a low pressure is preferable as much as possible, but if the pressure is too low, the film formation rate will decrease.

【0032】酸化ガスとしては、O,O,NO,
NOなどが使える。低温化にはこれらの種類の選択と
プラズマなどのアシスト法を使うとよい。
As the oxidizing gas, O 2 , O 3 , N 2 O,
NO 2 etc. can be used. For lowering the temperature, selection of these types and assist methods such as plasma may be used.

【0033】PLZTの場合も上記のことがそのまま当
てはまる。La原料としては、La(dpm)、La
(dibm)[トリス(ジイソブチリルメタナート)
ランタン]などが使える。低温化には、後者のが好まし
い。また後者の方が種々の溶媒に良く溶けるので、少な
い溶媒で供給気化できる。これらのLa化合物とPb
(dpm)とを所定の比で混合し一つの原料容器から
供給すれば、組成の精度や均一性がよく、マスフローコ
ントローラーが1基で2原料を送れるなどの工業的利点
がある。
In the case of PLZT, the above applies as it is. As the La raw material, La (dpm) 3 , La
(Dibm) 3 [tris (diisobutyryl methanate)
Lantern] can be used. The latter is preferable for lowering the temperature. In addition, the latter is more soluble in various solvents, so that supply and vaporization can be performed with a small amount of solvent. These La compounds and Pb
If (dpm) 2 is mixed at a predetermined ratio and supplied from one raw material container, the composition has good accuracy and uniformity, and there are industrial advantages such that one mass flow controller can send two raw materials.

【0034】[0034]

【実施例】PZT薄膜の製造 原料容器1からPb(dpm)のシクロヘキサン溶液
(濃度0.5mol/l)をマスフローコントローラー
1を通し、240℃の気化器1に送り、予熱したArガ
ス300sccmとともに蒸発させ、ガス混合部に送っ
た。原料容器2からZr(OtBu)とTi(OtB
u)のモル比0.35/0.65の生の混合液0.1
0ml/minをマスフローコントローラー2を通し、
140℃の気化器2に送り、予熱したArガス70sc
cmとともに蒸発させ、ガス混合部に送った。2つの気
化器の圧力は成り行きで5〜7Torrであった。混合
部からのPb,Zr,Ti化合物のガスと、予熱したO
ガス400sccmをCVD室のシャワーヘッドに導
入し、Pt/SiO/Si基板上に導いた。CVD室
圧力は、1.0Torrで、基板温度は480℃であっ
た。20分成膜し200〜250nmの膜が得られた。
XRD分析より、膜は正方晶のペロブスカイトであっ
た。膜の一部を溶解し、ICP発光分光で組成分析を行
った。Pb(dpm)溶液の供給速度との関係を表3
に示す。
[Example] Production of PZT thin film A cyclohexane solution of Pb (dpm) 2 (concentration: 0.5 mol / l) was fed from a raw material container 1 through a mass flow controller 1 to a vaporizer 1 at 240 ° C. together with 300 sccm of preheated Ar gas. It was evaporated and sent to the gas mixing section. From the raw material container 2 Zr (OtBu) 4 and Ti (OtB)
u) 0.1 of a raw mixture of 4 with a molar ratio of 0.35 / 0.65
Pass 0 ml / min through the mass flow controller 2,
Preheated Ar gas 70sc sent to 140 ° C vaporizer 2.
It was evaporated together with cm and sent to the gas mixing section. The pressure of the two vaporizers was nominally 5-7 Torr. Pb, Zr, and Ti compound gas from the mixing section and preheated O
2 gas 400sccm introduced into the shower head CVD chamber, led to Pt / SiO 2 / Si substrate. The CVD chamber pressure was 1.0 Torr, and the substrate temperature was 480 ° C. The film was formed for 20 minutes to obtain a film having a thickness of 200 to 250 nm.
According to XRD analysis, the film was tetragonal perovskite. A part of the film was dissolved and the composition was analyzed by ICP emission spectroscopy. Table 3 shows the relationship with the supply rate of the Pb (dpm) 2 solution.
Shown in.

【0035】[0035]

【表3】 [Table 3]

【0036】この結果から、Pb(dpm)供給速度
0.50〜0.60ml/min間で、膜組成Pb/
(Zr+Ti)=1.00〜1.01が達成され、プロ
セスウィンドウが開いたことがわかる。またZr/Ti
も0.38〜0.39と一定にできたことがわかる。
From this result, the film composition Pb / Pb / (dpm) 2 was supplied at a rate of 0.50 to 0.60 ml / min.
It can be seen that (Zr + Ti) = 1.00 to 1.01 was achieved and the process window was opened. Also Zr / Ti
It can be seen that the value of 0.38 to 0.39 was also constant.

【0037】[0037]

【発明の効果】液体マスフローコントローラーと気化器
を使った原料供給方式で、PZT膜を成膜する際、膜組
成Pb/(Zr+Ti)=1となるプロセスウィンドウ
が開き、Zr/Tiが一定にできる。PZTやPLZT
膜の量産に有効である。
EFFECT OF THE INVENTION When a PZT film is formed by a raw material supply method using a liquid mass flow controller and a vaporizer, a process window with a film composition Pb / (Zr + Ti) = 1 can be opened and Zr / Ti can be kept constant. . PZT or PLZT
Effective for mass production of membranes.

Claims (7)

【特許請求の範囲】[Claims] 【請求項1】化学気相成長法によりPZT薄膜を製造す
る方法において、ビス(β−ジケトナート)鉛溶液とZ
r(OtBu)とTi(OtBu)と酸化剤を原料
として用いることを特徴とするPZT薄膜の製法。
1. A method for producing a PZT thin film by a chemical vapor deposition method, comprising a bis (β-diketonate) lead solution and Z.
A method for producing a PZT thin film, which comprises using r (OtBu) 4 , Ti (OtBu) 4, and an oxidant as raw materials.
【請求項2】ビス(β−ジケトナート)鉛がPb(dp
m)であることを特徴とする請求項1記載のPZT薄
膜の製法。
2. Bis (β-diketonate) lead is Pb (dp
m) 2. The method for producing a PZT thin film according to claim 1, wherein
【請求項3】ビス(β−ジケトナート)鉛溶液を気化器
1で気化させ、Zr(OtBu)とTi(OtBu)
との混合液を気化器2で気化させ、これら2つの気化
器からのガスと酸化剤を混合しCVD室に導入すること
を特徴とする請求項1および請求項2記載のPZT薄膜
の製法。
3. A bis (β-diketonate) lead solution is vaporized by a vaporizer 1 to obtain Zr (OtBu) 4 and Ti (OtBu).
4. The method for producing a PZT thin film according to claim 1 or 2, wherein the mixed liquid with 4 is vaporized in the vaporizer 2, and the gas from these two vaporizers and the oxidant are mixed and introduced into the CVD chamber. .
【請求項4】1つの原料容器からZr(OtBu)
Ti(OtBu)との所定比率の混合液を気化器2に
供給することを特徴とする請求項3記載のPZT薄膜の
製法。
4. The method for producing a PZT thin film according to claim 3, wherein a mixed liquid of Zr (OtBu) 4 and Ti (OtBu) 4 at a predetermined ratio is supplied to the vaporizer 2 from one raw material container.
【請求項5】基板温度が400〜500℃であることを
特徴とする請求項3および請求項4記載のPZT薄膜の
製法。
5. The method for producing a PZT thin film according to claim 3 or 4, wherein the substrate temperature is 400 to 500 ° C.
【請求項6】ビス(β−ジケトナート)鉛溶液の溶媒が
THF、トルエン、酢酸ブチル、シクロヘキサン、メチ
ルシクロヘキサン、エチルシクロヘキサンの群から選ば
れた1種であることを特徴とする請求項1〜5記載のP
ZT薄膜の製法。
6. The solvent for the bis (β-diketonate) lead solution is one selected from the group consisting of THF, toluene, butyl acetate, cyclohexane, methylcyclohexane and ethylcyclohexane. P described
Manufacturing method of ZT thin film.
【請求項7】PZT薄膜のPbを一部Laで置換した請
求項1〜6記載のPLZT薄膜の製法。
7. The method for producing a PLZT thin film according to claim 1, wherein Pb of the PZT thin film is partially replaced with La.
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