JPH0964307A - Heat treatment method of oxide thin film - Google Patents
Heat treatment method of oxide thin filmInfo
- Publication number
- JPH0964307A JPH0964307A JP7220010A JP22001095A JPH0964307A JP H0964307 A JPH0964307 A JP H0964307A JP 7220010 A JP7220010 A JP 7220010A JP 22001095 A JP22001095 A JP 22001095A JP H0964307 A JPH0964307 A JP H0964307A
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- Prior art keywords
- heat treatment
- oxygen
- film
- discharge
- treatment method
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は酸化物薄膜の熱処理方法
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method for an oxide thin film.
【０００２】[0002]
【従来の技術】半導体記憶装置の容量絶縁膜として、高
誘電率絶縁膜であるＴａ2Ｏ5（五酸化タンタル）を用い
ることが検討されている。その場合、立体的な構造の電
極上に形成することを目的としているため、タンタルの
有機化合物（例えばペンタエトキシタンタル）を原料と
した化学的気相成長法が用いられる。しかし、Ｔａ2Ｏ5
膜が形成された時点では酸素欠損や原料から混入する不
純物炭素が多く、リーク電流が極めて大きいため、形成
後の熱処理が必須である。2. Description of the Related Art The use of Ta 2 O 5 (tantalum pentoxide), which is a high-dielectric-constant insulating film, has been studied as a capacitive insulating film for semiconductor memory devices. In that case, since the purpose is to form it on an electrode having a three-dimensional structure, a chemical vapor deposition method using an organic compound of tantalum (for example, pentaethoxytantalum) as a raw material is used. However, Ta 2 O 5
At the time when the film is formed, oxygen deficiency and a large amount of impurity carbon mixed from the raw material cause an extremely large leak current, so that heat treatment after formation is essential.
【０００３】酸素欠損の修復や不純物炭素の除去のため
には、通常７００℃以上の酸素雰囲気中での熱処理が必
要である。しかし７００℃以上ではＴａ2Ｏ5膜が結晶化
し、結晶粒界によるリーク電流の増大が生じてしまう。
そこで、低温(７００℃以下)でも効果的に酸素欠損を修
復するために、活性酸素雰囲気中での熱処理方法が検討
された。例えば、プラズマによってあらかじめ酸素分子
をオゾンに励起して熱処理室に輸送し、それを処理室内
で低圧水銀ランプで励起して酸素ラジカルを生成させて
熱処理する方法が考案された（ＵＶオゾン熱処理法）。In order to repair oxygen vacancies and remove impurity carbon, it is usually necessary to perform heat treatment in an oxygen atmosphere at 700 ° C. or higher. However, at 700 ° C. or higher, the Ta 2 O 5 film is crystallized, and the leak current increases due to the crystal grain boundaries.
Therefore, in order to effectively repair oxygen vacancies even at low temperatures (700 ° C. or lower), a heat treatment method in an active oxygen atmosphere has been studied. For example, a method has been devised in which oxygen molecules are excited into ozone in advance by plasma and transported to a heat treatment chamber, which is excited by a low pressure mercury lamp in the treatment chamber to generate oxygen radicals and heat treated (UV ozone heat treatment method). .
【０００４】これらの公知例として、特開平2−283022
号公報や、「テクニカル ダイジェスト オブ シンポ
ジウム オン ブイエルエスアイ テクノロジー(Techn
icalDigest of Symposium on VLSI Technology），p.２
５(１９８９)」が挙げられる。また、酸素をプラズマで
活性化し、Ｔａ2Ｏ5膜をプラズマ中に曝しながら熱処理
する方法（酸素プラズマ熱処理法）として、特開平4−1
99828 号公報や、「エクステンディッド アブストラク
ツ オブ コンファレンス オン ソリッドステイト
デバイスイズ アンド マテリアルズ（Extended Abstr
acts of Conference on Solid State Devides and Mate
rials)，p.８６２（１９９３）」が挙げられる。As a publicly known example of these, Japanese Patent Application Laid-Open No. 2-283022
Issue, and "Technical Digest of Symposium on BSI Technology (Technical Digest
icalDigest of Symposium on VLSI Technology), p.2
5 (1989) ”. Further, as a method (oxygen plasma heat treatment method) in which oxygen is activated by plasma and the Ta 2 O 5 film is subjected to heat treatment while being exposed to the plasma, there is disclosed in Japanese Patent Laid-Open No. 4-1
99828 bulletin and "Extended Abstracts of Conference on Solid State"
Device is and Materials (Extended Abstr
acts of Conference on Solid State Devides and Mate
rials), p. 862 (1993) ”.
【０００５】[0005]
【発明が解決しようとする課題】ＵＶオゾン熱処理法の
代表的な装置例を図２に示す。プラズマ発生器７によっ
てあらかじめ酸素分子をオゾンに励起して熱処理室に輸
送し、それを処理室内で低圧水銀ランプ８で励起して酸
素ラジカルを生成させて熱処理する方法である。酸素欠
損を十分に修復するためには熱処理温度を高温化する必
要があるが、オゾンは３００℃以上では容易に酸素分子
に解離してしまうため、この方法では熱処理時の基板温
度を３００℃以上に高温化すると酸素欠損修復効果が小
さくなる。そのため、より高温での熱処理が可能となる
方法が必要である。A typical apparatus example of the UV ozone heat treatment method is shown in FIG. This is a method in which oxygen molecules are excited into ozone in advance by a plasma generator 7 and transported to a heat treatment chamber, which is excited by a low pressure mercury lamp 8 in the treatment chamber to generate oxygen radicals and heat treated. It is necessary to raise the heat treatment temperature in order to sufficiently repair the oxygen deficiency, but since ozone is easily dissociated into oxygen molecules at 300 ° C. or higher, in this method, the substrate temperature during heat treatment is 300 ° C. or higher. The effect of repairing oxygen deficiency becomes smaller when the temperature becomes higher. Therefore, a method that enables heat treatment at a higher temperature is needed.
【０００６】次に酸素プラズマ熱処理法の代表的な装置
例を図３に示す。酸素をプラズマ発生器７で活性化し、
Ｔａ2Ｏ5膜をプラズマ中に曝しながら熱処理する方法で
ある。この方法ならば、酸素ラジカルを基板表面で常に
生成し続けることができるため、基板温度を３００℃以
上に高温化しても酸素欠損修復効果がある。しかしプラ
ズマによって酸素イオンも生成されるため、Ｔａ2Ｏ5膜
がイオン損傷を受け、新たなリーク電流の要因が生じて
しまう。そのため、Ｔａ2Ｏ5膜に損傷を与えることなく
酸素欠損を修復し、リーク電流を効果的に低減できる熱
処理方法が求められていた。Next, a typical apparatus example of the oxygen plasma heat treatment method is shown in FIG. Oxygen is activated by the plasma generator 7,
This is a method of heat treatment while exposing the Ta 2 O 5 film to plasma. According to this method, oxygen radicals can be continuously generated on the surface of the substrate, so that even if the substrate temperature is raised to 300 ° C. or higher, the oxygen deficiency repairing effect can be obtained. However, since oxygen ions are also generated by the plasma, the Ta 2 O 5 film is ion-damaged, which causes a new leak current factor. Therefore, there has been a demand for a heat treatment method capable of repairing oxygen vacancies and effectively reducing leak current without damaging the Ta 2 O 5 film.
【０００７】さらに我々の検討によって、酸素プラズマ
熱処理を施してキャパシタを形成した後、４５０℃の熱
工程を通すとキャパシタのリーク電流が増大することが
わかった。前述したようにＴａ2Ｏ5膜中には原料から混
入する不純物炭素が数％〜数十％程度混入しており、４
５０℃程度の熱工程でも容易に結合が切断されてリーク
電流の原因となる欠陥を生じさせるためである。Ｔａ2
Ｏ5膜を半導体記憶素子の容量絶縁膜として採用する場
合、配線工程を考慮すると４５０℃以上の耐熱性が必要
となる。そこで、４５０℃程度でも切断されない強い炭
素結合を形成でき、キャパシタ形成後の熱工程でもリー
ク電流を増大させることのない熱処理方法が求められて
いた。Further, according to our study, it has been found that the leakage current of the capacitor increases when a thermal process of 450 ° C. is performed after the oxygen plasma heat treatment is performed to form the capacitor. As described above, in the Ta 2 O 5 film, the impurity carbon mixed from the raw material is mixed in the range of several% to several tens%.
This is because even in a heating process at about 50 ° C., the bond is easily broken to cause a defect that causes a leak current. Ta 2
When the O 5 film is used as the capacitive insulating film of the semiconductor memory element, heat resistance of 450 ° C. or higher is required considering the wiring process. Therefore, there has been a demand for a heat treatment method that can form a strong carbon bond that is not broken even at about 450 ° C. and that does not increase the leakage current even in the heat step after forming the capacitor.
【０００８】[0008]
【課題を解決するための手段】上記の二つの課題を解決
するために、酸素ラジカル熱処理法を考案した。これ
は、ＲＦ無電極放電によって電気的に中性な原子状酸素
(酸素ラジカル)を発生させ、昇温されたＴａ2Ｏ5膜に照
射する方法である。この熱処理方法を用いることによっ
て、Ｔａ2Ｏ5膜にイオン損傷を生成させることなく酸素
欠損を修復することができる。また炭素に対する酸化力
が強いため、Ｔａ2Ｏ5膜中の炭素を７００℃以下の温度
でも酸化除去でき、膜中に残った炭素も容易に切断され
ない結合状態となる。そのため、キャパシタ形成後の４
５０℃程度の熱工程を通してもリーク電流の増大が少な
いＴａ2Ｏ5膜が形成できる。In order to solve the above two problems, an oxygen radical heat treatment method was devised. This is an electrically neutral atomic oxygen by RF electrodeless discharge.
This is a method of generating (oxygen radicals) and irradiating the heated Ta 2 O 5 film. By using this heat treatment method, oxygen vacancies can be repaired without generating ion damage in the Ta 2 O 5 film. Further, since the oxidizing power for carbon is strong, the carbon in the Ta 2 O 5 film can be oxidized and removed even at a temperature of 700 ° C. or less, and the carbon remaining in the film is in a bonded state that is not easily cut. Therefore, 4 after capacitor formation
It is possible to form a Ta 2 O 5 film with a small increase in leak current even through a heating process at about 50 ° C.
【０００９】[0009]
【作用】イオン損傷を生じさせることなく酸素欠損を修
復でき、加えて膜中の不純物炭素を７００℃以下の低温
でも十分に除去または強い結合を実現できる。The oxygen deficiency can be repaired without causing ion damage, and the impurity carbon in the film can be sufficiently removed or a strong bond can be realized even at a low temperature of 700 ° C. or lower.
【００１０】[0010]
【実施例】本発明を実施するための熱処理装置を図１に
示す。基板加熱ヒータを備えた試料台５と、酸素ガスを
導入するラインを備えている。酸素の流量はマスフロー
コントローラによって制御する。排気系として、ターボ
モレキュラポンプとロータリポンプを備えており、１０
-8Torrまで排気できる。また、ＲＦ無電極放電によって
電気的に中性な酸素ラジカルを発生できるラジカル源１
を備えている。放電管３内に酸素を導入してＲＦコイル
２に１３.５６ＭＨｚ の高周波電力を印加することによ
り放電管内の酸素に放電を起こさせる。プラズマ放電を
起こしたガス分子は放電管の内壁との衝突によって解離
して活性な原子状酸素(酸素ラジカル)となり、アルミナ
製アパーチャプレート４の小さな穴(０.５mm）から真空
チャンバ内に放出され、試料６に照射される。DESCRIPTION OF THE PREFERRED EMBODIMENTS A heat treatment apparatus for carrying out the present invention is shown in FIG. A sample stage 5 equipped with a substrate heating heater and a line for introducing oxygen gas are provided. The flow rate of oxygen is controlled by the mass flow controller. The exhaust system includes a turbo molecular pump and a rotary pump.
-Can exhaust up to -8 Torr. Further, a radical source 1 capable of generating electrically neutral oxygen radicals by RF electrodeless discharge
It has. By introducing oxygen into the discharge tube 3 and applying high-frequency power of 13.56 MHz to the RF coil 2, the oxygen in the discharge tube is discharged. The gas molecules that have generated plasma discharge are dissociated by collision with the inner wall of the discharge tube and become active atomic oxygen (oxygen radicals), which are released from the small holes (0.5 mm) of the aperture plate 4 made of alumina into the vacuum chamber. , The sample 6 is irradiated.
【００１１】酸素ラジカル源から発生する活性種を同定
するために、プラズマ分光分析を行った。分光器は高感
度マルチチャネル分光測定装置を用いた。分光分析の際
にはラジカルビーム源が覗き窓の正面にくるように配置
を変え、覗き窓越しに検出器をおき、光ファイバで分光
器まで光を導くという配置を用いて測定した。Plasma spectroscopic analysis was performed to identify active species generated from the oxygen radical source. A high-sensitivity multi-channel spectrophotometer was used as the spectroscope. In the spectroscopic analysis, the arrangement was changed so that the radical beam source was located in front of the viewing window, a detector was placed through the viewing window, and light was guided to the spectroscope by an optical fiber.
【００１２】測定結果を図４に示す。波長３９４.７ｎ
ｍ，４３６.９ｎｍ，５３２.９ｎｍ,６１５.８ｎｍ，６
４５.７ｎｍ，７００.２ｎｍ，７２５.５ｎｍ,７７７.
５ｎｍが酸素ラジカルによる発光である。それと比較し
て、酸素イオンによる発光である波長５２５.１ｎｍ，
５５９.７ｎｍ，５９７.３ｎｍ のピークは非常に小さ
く、少なくとも酸素ラジカルに対する濃度は０.１％ 以
下であった。ここで、最も大きいピークである７７７.
５ｎｍの発光は、３ｐ5Ｐ(主量子数＝３，５重項Ｐ)か
ら３ｓ5Ｓ0（主量子数＝３，５重項Ｓ）への遷移による
発光に対応しており、基底状態から約１１ｅＶ励起され
た酸素ラジカルである。この発光を持つ酸素ラジカル
が、Ｔａ2Ｏ5膜の不純物炭素除去および酸素欠損修復に
大きな効果を発揮する。原子状酸素の中で、７５０ｎｍ
以上の発光をもつものが９０％以上であった。The measurement results are shown in FIG. Wavelength 394.7n
m, 436.9 nm, 532.9 nm, 615.8 nm, 6
45.7 nm, 700.2 nm, 725.5 nm, 777.
The emission of 5 nm is due to oxygen radicals. In comparison, the wavelength of 525.1 nm, which is the emission due to oxygen ions,
The peaks at 559.7 nm and 597.3 nm were very small, and the concentration of oxygen radicals was at least 0.1% or less. Here, the largest peak is 777.
The emission at 5 nm corresponds to the emission due to the transition from 3p 5 P (main quantum number = 3, quintet P) to 3s 5 S 0 (main quantum number = 3, quintuplet S), and the ground state Is an oxygen radical excited by about 11 eV. The oxygen radicals having this light emission show a great effect in removing impurity carbon and repairing oxygen vacancies in the Ta 2 O 5 film. 750 nm in atomic oxygen
90% or more had the above-mentioned light emission.
【００１３】本発明による熱処理方法の効果を立証する
ために用いた試料の、作製手順を説明する。試料構造を
図５に示す。Ｓｉ基板９はｎ型で０.０１Ωcm 程度の低
抵抗のものを用いた。まず、１／２０に希釈したＨＦ溶
液中に２分間浸し、水切れすることを確認した後、水
洗，乾燥させた。その後、下部電極１０として、原料ガ
スとしてＳｉＨ4，Ｈ2，ＰＨ3を用い、Ｐ（リン）を１c
m3当り４×１０20個ドーピングしたＳｉ膜をＣＶＤ法に
よって２００ｎｍ形成し、Ｎ2 雰囲気中で８００℃、１
０分の多結晶化を行った。さらにＮＨ4 雰囲気中で８０
０℃、１分の窒化を行い、多結晶化Ｓｉ表面の約２ｎｍ
をＳｉ窒化膜１１に変えた。これは、Ｔａ2Ｏ5膜形成中
および形成後の熱処理によって下部電極が酸化し、容量
が低下するのを抑制するためである。その後、Ｔａ2Ｏ5
膜１２を化学的気相成長法で形成した。ペンタエトキシ
タンタル（原料容器を１２５℃に加熱，キャリアガスは
Ｎ2：５０sccm）と酸素（６００sccm）を原料とし、成
膜室圧力０.２Torr，基板温度４２０℃で膜厚８ｎｍ形
成した。A procedure for producing a sample used for demonstrating the effect of the heat treatment method according to the present invention will be described. The sample structure is shown in FIG. The Si substrate 9 was an n-type and had a low resistance of about 0.01 Ωcm. First, it was immersed in an HF solution diluted to 1/20 for 2 minutes, and after confirming that water was drained, it was washed with water and dried. Then, as the lower electrode 10, SiH 4 , H 2 , and PH 3 are used as source gases, and P (phosphorus) is added to 1 c.
A Si film doped with 4 × 10 20 per m 3 is formed to a thickness of 200 nm by the CVD method, and the temperature is 800 ° C. in an N 2 atmosphere.
Polycrystallization was performed for 0 minutes. 80 in NH 4 atmosphere
Nitrided at 0 ° C for 1 minute to obtain a polycrystallized Si surface of about 2 nm
Was changed to the Si nitride film 11. This is because the lower electrode is prevented from being oxidized by the heat treatment during and after the formation of the Ta 2 O 5 film to reduce the capacitance. After that, Ta 2 O 5
The film 12 was formed by chemical vapor deposition. Pentaethoxytantalum (heating the raw material container to 125 ° C., carrier gas N 2 : 50 sccm) and oxygen (600 sccm) were used as raw materials, and a film thickness of 8 nm was formed at a film forming chamber pressure of 0.2 Torr and a substrate temperature of 420 ° C.
【００１４】その後、本発明による熱処理と、比較のた
めに従来例の熱処理を施し、電気的特性の評価のために
上部電極を形成した。上部電極はＴｉＣｌ4とＮＨ4を原
料とするＣＶＤ法によってＴｉＮ膜１３を５０ｎｍ形成
し、公知のリソグラフィー／エッチング法によって１０
０μｍ角に加工した。After that, the heat treatment according to the present invention and the heat treatment of the conventional example were performed for comparison, and an upper electrode was formed for evaluation of electrical characteristics. For the upper electrode, a TiN film 13 having a thickness of 50 nm is formed by a CVD method using TiCl 4 and NH 4 as raw materials, and the TiN film 13 is formed by a known lithography / etching method.
It was processed into a 0 μm square.
【００１５】本発明によって熱処理を行ったＴａ2Ｏ5膜
の電圧−電流密度特性を、他の熱処理方法と比較して図
６に示す。ＵＶオゾン熱処理条件は基板温度２８０℃，
圧力は常圧とした。酸素プラズマ熱処理条件は、基板温
度４００℃，圧力１０Torr，ＲＦ周波数１３.５６ＭＨ
ｚ とした。酸素ラジカル熱処理の条件は、基板温度４
００℃，圧力１０-6Torr，ＲＦ周波数１３.５６ＭＨｚ
とした。いずれの場合も、熱処理時間は１０分に統一し
た。ＳｉＯ2換算膜厚はいずれも２.５ｎｍであった。FIG. 6 shows the voltage-current density characteristics of the Ta 2 O 5 film heat-treated according to the present invention in comparison with other heat treatment methods. UV ozone heat treatment conditions are substrate temperature 280 ° C,
The pressure was normal pressure. Oxygen plasma heat treatment conditions are: substrate temperature 400 ° C., pressure 10 Torr, RF frequency 13.56 MH
z. The conditions for the oxygen radical heat treatment are a substrate temperature of 4
00 ℃, pressure 10 -6 Torr, RF frequency 13.56MHz
And In each case, the heat treatment time was unified to 10 minutes. The equivalent SiO 2 film thickness was 2.5 nm.
【００１６】図６からわかるように、本発明による酸素
ラジカル熱処理法は、他の熱処理法に比べてＴａ2Ｏ5膜
のリーク電流密度の低減効果が大きいことがわかる。Ｕ
Ｖオゾン熱処理法よりリーク電流低減効果が大きいの
は、熱処理温度を高温化できるためである。また、酸素
プラズマ熱処理法よりリーク電流低減効果が大きいの
は、酸素イオンによる損傷を受けないためである。As can be seen from FIG. 6, the oxygen radical heat treatment method according to the present invention is more effective in reducing the leak current density of the Ta 2 O 5 film than other heat treatment methods. U
The effect of reducing the leak current is greater than that of the V ozone heat treatment method because the heat treatment temperature can be increased. Moreover, the reason why the leakage current reducing effect is larger than that of the oxygen plasma heat treatment method is that it is not damaged by oxygen ions.
【００１７】酸素ラジカルに対する酸素イオンの濃度
は、少なければ少ないほどイオン損傷の影響が小さく、
リーク電流低減の効果がある。図７に示すように、ＤＲ
ＡＭ動作に必要とされる１.２５Ｖ の耐圧を持つために
はイオン状の酸素濃度は１０％以下にする必要がある。
イオン状酸素濃度を１％以下に抑えると、０.１Ｖ の耐
圧余裕を持つことができ、さらに望ましくは０.１％以
下に抑えると、０.２Ｖの耐圧余裕を持つことができ
る。The smaller the concentration of oxygen ions with respect to the oxygen radicals, the smaller the effect of ion damage.
It has the effect of reducing the leakage current. As shown in FIG.
In order to have a withstand voltage of 1.25 V required for AM operation, the ionic oxygen concentration must be 10% or less.
If the ionic oxygen concentration is suppressed to 1% or less, a withstand voltage margin of 0.1 V can be obtained, and more preferably, if it is suppressed to 0.1% or less, a withstand voltage margin of 0.2 V can be obtained.
【００１８】次に、キャパシタ形成後に窒素雰囲気中で
４５０℃，９０分の熱工程を通して、再び電圧−電流密
度特性を評価した。結果を図８に示す。酸素プラズマ熱
処理を施したものは、４５０℃の熱工程によってリーク
電流が大きく増大してしまうのに対し、酸素ラジカル熱
処理を施したものはリーク電流の増大が小さい。酸素ラ
ジカルは炭素に対する酸化力が強いため、Ｔａ2Ｏ5膜中
の炭素を酸化除去でき、膜中に残った炭素も容易に切断
されない結合状態となったためである。そのため、キャ
パシタ形成後の４５０℃の熱処理によってもリーク電流
の増大が少ないＴａ2Ｏ5膜が形成できた。Next, the voltage-current density characteristics were evaluated again through a thermal process at 450 ° C. for 90 minutes in a nitrogen atmosphere after forming the capacitor. The results are shown in Fig. 8. The one subjected to the oxygen plasma heat treatment has a large increase in the leakage current due to the heat treatment at 450 ° C., whereas the one subjected to the oxygen radical heat treatment has a small increase in the leakage current. This is because the oxygen radical has a strong oxidizing power for carbon, so that the carbon in the Ta 2 O 5 film can be oxidized and removed, and the carbon remaining in the film also becomes a bond state that is not easily cut. Therefore, a Ta 2 O 5 film with a small increase in leak current could be formed even by the heat treatment at 450 ° C. after the formation of the capacitor.
【００１９】それぞれ酸素プラズマおよび酸素ラジカル
熱処理を施したＴａ2Ｏ5膜中炭素の昇温脱離分析結果を
図９に示す。比較のために熱処理を施していない（ａｓ
−ｄｅｐｏ）Ｔａ2Ｏ5膜の測定結果も示してある。ａｓ
−ｄｅｐｏの場合、１００℃から７００℃の広い範囲で
ＣＨ4 ，ＣＯの脱離が観測されており、ＣＯに比べると
ＣＨ4 の脱離が多い。酸素プラズマ熱処理を施したもの
は、１００℃から４００℃の間で脱離し、ＣＨ4 に比べ
てＣＯの脱離が増加する。これはＴａ2Ｏ5膜中の炭素が
酸素プラズマによって弱い酸素結合をし、容易に脱離し
やすくなったためである。この脱離する炭素が、キャパ
シタ形成後の熱工程によってリーク電流を増大させる原
因である。酸素ラジカル熱処理を施したものは、酸素プ
ラズマ熱処理に比べてＣＯの脱離が少なく、ＣＨ4 の脱
離は観測されない。これは、前述したように酸素ラジカ
ルは炭素に対する酸化力が強いため、Ｔａ2Ｏ5膜中の炭
素を十分に酸化除去できたためである。また、膜中に残
存している炭素も容易に切断されない強い結合状態とな
るため、７００℃以下では脱離しにくくなったものと考
えられる。FIG. 9 shows the results of thermal desorption analysis of carbon in the Ta 2 O 5 film subjected to oxygen plasma and oxygen radical heat treatment, respectively. No heat treatment is applied for comparison (as
-Depo) Ta 2 O 5 film measurements also are shown. as
In the case of −depo, desorption of CH 4 and CO is observed in a wide range from 100 ° C. to 700 ° C., and desorption of CH 4 is larger than that of CO. Those subjected to the oxygen plasma heat treatment are desorbed between 100 ° C. and 400 ° C., and CO desorption is increased as compared with CH 4 . This is because the carbon in the Ta 2 O 5 film was weakly oxygen-bonded by the oxygen plasma and easily desorbed. The desorbed carbon is a cause of increasing the leak current due to the thermal process after the formation of the capacitor. In the case of the oxygen radical heat treatment, the desorption of CO is less than that of the oxygen plasma heat treatment, and the desorption of CH 4 is not observed. This is because oxygen radicals have a strong oxidizing power for carbon as described above, and thus carbon in the Ta 2 O 5 film could be sufficiently oxidized and removed. Further, it is considered that the carbon remaining in the film is in a strong bond state in which it is not easily cut, so that desorption becomes difficult at 700 ° C. or lower.
【００２０】ここで、酸素ラジカル熱処理法のシーケン
スについて付け加えておく。所定時間の熱処理終了後、
２００℃程度まで降温してから酸素ラジカル照射を停止
する方法と、酸素ラジカル照射を停止してから降温を開
始する方法とがある。前者の場合、Ｔａ2Ｏ5膜中に残存
する不純物炭素がさらに酸化されるため、キャパシタ形
成後の熱工程によって炭素の脱離があり、リーク電流密
度が若干増加する。実施例ではこの手順で酸素ラジカル
熱処理を行っている。後者の方法を用いればＴａ2Ｏ5膜
中の炭素が酸化されずに閉じ込められるため熱工程によ
る劣化は無くなる。しかし、高温で真空中（又は酸素分
子中）に放置されることになり、Ｔａ2Ｏ5膜中の酸素の
脱離等が生じるため、初期特性が前者の方法によるもの
に比べて劣る。結果的にはキャパシタ形成後の熱工程後
の電気的特性に大差は無く、どちらの方法を用いるかは
設計事項である。The sequence of the oxygen radical heat treatment method will be added here. After the heat treatment for a predetermined time,
There are a method of lowering the temperature to about 200 ° C. and then stopping the oxygen radical irradiation, and a method of stopping the oxygen radical irradiation and then starting the temperature decrease. In the former case, the impurity carbon remaining in the Ta 2 O 5 film is further oxidized, so that the carbon is desorbed by the thermal process after the formation of the capacitor, and the leak current density slightly increases. In the example, the oxygen radical heat treatment is performed by this procedure. If the latter method is used, carbon in the Ta 2 O 5 film is confined without being oxidized, so that deterioration due to a thermal process is eliminated. However, since it is left in a vacuum (or in oxygen molecules) at a high temperature, oxygen in the Ta 2 O 5 film is desorbed, and the initial characteristics are inferior to those obtained by the former method. As a result, there is no great difference in the electrical characteristics after the thermal process after forming the capacitor, and which method is used is a design matter.
【００２１】酸素ラジカル熱処理温度は３００℃以上で
効果があり、高温化するほど酸素欠損修復効果および不
純物炭素除去効果が大きくなって、低リークかつ熱工程
による劣化が少ないＴａ2Ｏ5膜が得られる。しかし、７
００℃以上ではＴａ2Ｏ5膜が結晶化し、結晶粒界からの
リーク電流増大が生じてしまうため、熱処理温度は７０
０℃以下に限定される。また、高温になると基板のシリ
コンとＴａ2Ｏ5の界面でのシリコン酸化膜の成長が著し
くなり容量が低下してしまうため、熱処理温度は６００
℃以下が望ましい。また、キャパシタ形成後の熱工程の
許容温度は７００℃以下であり、可能ならば５５０℃以
下が望ましい。The oxygen radical heat treatment temperature is effective at 300 ° C. or higher, and as the temperature increases, the oxygen deficiency repairing effect and the impurity carbon removing effect increase, and a Ta 2 O 5 film with low leak and less deterioration due to the heat process is obtained. To be But 7
At a temperature of 00 ° C. or higher, the Ta 2 O 5 film is crystallized and the leak current from the crystal grain boundary increases, so that the heat treatment temperature is 70
Limited to 0 ° C or lower. Further, when the temperature becomes high, the growth of the silicon oxide film at the interface between the silicon of the substrate and Ta 2 O 5 becomes remarkable and the capacity decreases, so that the heat treatment temperature is 600
C or lower is desirable. In addition, the allowable temperature of the thermal process after forming the capacitor is 700 ° C. or lower, and if possible, 550 ° C. or lower is desirable.
【００２２】酸素ラジカル熱処理時間については、長時
間行うほど酸素欠損修復効果および不純物炭素除去効果
が大きくなって、低リークかつ熱工程による劣化が少な
いＴａ2Ｏ5膜が得られる。しかし、３０分以上になると
基板のシリコンとＴａ2Ｏ5の界面でのシリコン酸化膜の
成長が著しくなり容量が低下してしまうため、熱処理温
度は３０分以下に限定され、可能ならば１０分以下が望
ましい。Regarding the oxygen radical heat treatment time, the longer the time is, the greater the oxygen deficiency repairing effect and the impurity carbon removing effect are, and a Ta 2 O 5 film having a low leak and less deterioration due to the thermal process can be obtained. However, if the time exceeds 30 minutes, the growth of the silicon oxide film at the interface between the silicon of the substrate and Ta 2 O 5 will be remarkable and the capacity will decrease, so the heat treatment temperature is limited to 30 minutes or less, and if possible, 10 minutes. The following is desirable.
【００２３】実施例で、Ｔａ2Ｏ5膜の堆積法としてペン
タエトキシタンタルを原料とした化学的気相成長法を用
いたが、Ｔａの原料はＴａ(ＯＣＨ3)5，Ｔａ(Ｎ(ＣＨ3)
2)5などの他のＴａ有機物ソースを用いて形成したＴａ2
Ｏ5膜でも効果が確認された。In the example, the chemical vapor deposition method using pentaethoxytantalum as a raw material was used as the deposition method of the Ta 2 O 5 film, but the raw material of Ta is Ta (OCH 3 ) 5 , Ta (N (CH 3 )
2 ) Ta 2 formed using other Ta organic source such as 5
The effect was also confirmed with the O 5 film.
【００２４】ここではキャパシタの下部電極として多結
晶シリコンを用いたが、それに代わって金属材料、例え
ば、ＷやＰｔを用いても同様の効果が得られた。Although polycrystalline silicon is used as the lower electrode of the capacitor here, the same effect can be obtained by using a metal material such as W or Pt instead.
【００２５】上部電極についてもＴｉＮ以外にＰｔやＷ
を用いることができる。形成方法についてもＣＶＤに限
ったものではなく、スパッタ法を用いてもよい。As for the upper electrode, in addition to TiN, Pt and W
Can be used. The forming method is not limited to CVD, and a sputtering method may be used.
【００２６】さらに、本発明による酸素ラジカル熱処理
法を用いてダイナミック・ランダム・アクセス・メモリ
（ＤＲＡＭ）を作製した。メモリセルの断面図を図１０
に示す。ここで、容量素子ＳｉＯ2 換算膜厚２.５ｎｍ
(Ｔａ2Ｏ5膜厚８ｎｍ）で耐圧１.２５Ｖ（判定電流密度
１０-8Ａ／cm2）を満足しており、さらにＤＲＡＭとし
ての動作が確認された。下部電極構造として、ここでは
厚膜型を用いたが、円筒型やフィン型を用いても同様の
効果が得られる。Further, a dynamic random access memory (DRAM) was manufactured by using the oxygen radical heat treatment method according to the present invention. FIG. 10 is a sectional view of the memory cell.
Shown in Here, the capacitance element SiO 2 converted film thickness is 2.5 nm.
(Ta 2 O 5 film thickness 8 nm), the withstand voltage of 1.25 V (judgment current density 10 −8 A / cm 2 ) was satisfied, and further the operation as a DRAM was confirmed. Although the thick film type is used here as the lower electrode structure, the same effect can be obtained by using a cylindrical type or a fin type.
【００２７】本発明によって形成された容量素子は、通
信用ＬＳＩなどで大容量を必要とするコンデンサ部分に
も適用できる。The capacitive element formed according to the present invention can also be applied to a capacitor portion requiring a large capacity in a communication LSI or the like.
【００２８】さらに、容量素子としてだけでなく、ＭＯ
Ｓのゲート酸化膜の形成工程に適用しても、従来方法よ
りも高い絶縁耐圧を有する酸化膜が得られる。Furthermore, not only as a capacitive element but also as an MO
Even when applied to the step of forming the S gate oxide film, an oxide film having a higher withstand voltage than the conventional method can be obtained.
【００２９】[0029]
【発明の効果】本発明によれば、ＵＶオゾン熱処理法や
酸素プラズマ熱処理法に比べてリーク電流が小さく、キ
ャパシタ形成後の４５０℃の熱工程を通してもリーク電
流の増大が少ないＴａ2Ｏ5膜を作製することが可能にな
った。According to the present invention, the Ta 2 O 5 film has a smaller leak current than the UV ozone heat treatment method or the oxygen plasma heat treatment method and has a small increase in the leak current even through the heat treatment at 450 ° C. after the formation of the capacitor. It has become possible to make
【図１】酸素ラジカル熱処理装置の実施例の説明図。FIG. 1 is an explanatory diagram of an embodiment of an oxygen radical heat treatment apparatus.
【図２】従来技術による熱処理装置のＵＶオゾン熱処理
法の説明図。FIG. 2 is an explanatory view of a UV ozone heat treatment method of a heat treatment apparatus according to a conventional technique.
【図３】従来技術による熱処理装置の酸素プラズマ熱処
理法の説明図。FIG. 3 is an explanatory diagram of an oxygen plasma heat treatment method of a heat treatment apparatus according to a conventional technique.
【図４】酸素ラジカルの発光スペクトル特性図。FIG. 4 is an emission spectrum characteristic diagram of oxygen radicals.
【図５】電気的特性評価に用いた試料構造の説明図。FIG. 5 is an explanatory diagram of a sample structure used for electrical characteristic evaluation.
【図６】ラジカル熱処理後の電圧−電流密度特性を従来
方法と比較して示す特性図。FIG. 6 is a characteristic diagram showing voltage-current density characteristics after radical heat treatment in comparison with a conventional method.
【図７】耐圧のイオン状酸素濃度依存性の特性図。FIG. 7 is a characteristic diagram of ionic oxygen concentration dependence of pressure resistance.
【図８】熱工程前後の電圧−電流密度特性図。FIG. 8 is a voltage-current density characteristic diagram before and after a heating process.
【図９】昇温脱離分析結果の特性図。FIG. 9 is a characteristic diagram of a thermal desorption analysis result.
【図１０】酸素ラジカル熱処理用いて作製したＤＲＡＭ
の要部の断面図。FIG. 10: DRAM manufactured using oxygen radical heat treatment
Sectional drawing of the principal part of FIG.
１…酸素ラジカル源、２…ＲＦコイル、３…放電管、４
…アパーチャプレート、５…試料台、６…試料。1 ... Oxygen radical source, 2 ... RF coil, 3 ... Discharge tube, 4
... Aperture plate, 5 ... Sample stage, 6 ... Sample.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０１Ｌ 21/822 (72)発明者 飯島 晋平 東京都小平市上水本町５丁目20番１号 株 式会社日立製作所半導体事業部内 (72)発明者 大路 譲 東京都小平市上水本町５丁目20番１号 株 式会社日立製作所半導体事業部内─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI Technical display location H01L 21/822 (72) Inventor Shinpei Iijima 5-20-1 Kamimizumotocho, Kodaira-shi, Tokyo Ceremony Company, Hitachi, Ltd. Semiconductor Division (72) Inventor, Yuzuru Oji, 5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Stock Company, Hitachi, Ltd., Semiconductor Division
Claims (5)
する方法であって、熱処理は原子状酸素を前記タンタル
酸化膜に照射することによって行われることを特徴とす
る酸化物薄膜の熱処理方法。1. A method for heat treating a tantalum oxide film in an oxidizing atmosphere, wherein the heat treatment is performed by irradiating the tantalum oxide film with atomic oxygen.
する方法であって、熱処理はＲＦ無電極放電によって発
生した原子状酸素を前記タンタル酸化膜に照射すること
によって行われることを特徴とする酸化物薄膜の熱処理
方法。2. A method for heat-treating a tantalum oxide film in an oxidizing atmosphere, wherein the heat treatment is performed by irradiating the tantalum oxide film with atomic oxygen generated by RF electrodeless discharge. Heat treatment method for oxide thin film.
に含まれるイオン状酸素の濃度が、前記原子状酸素に対
して１０％以下である酸化物薄膜の熱処理方法。3. The heat treatment method for an oxide thin film according to claim 1, wherein the concentration of ionic oxygen contained in the atmosphere of the heat treatment is 10% or less with respect to the atomic oxygen.
に含まれる原子状酸素の中で、750ｎｍ以上の発光波長
をもつものが９０％以上含まれている酸化物薄膜の熱処
理方法。4. The heat treatment method for an oxide thin film according to claim 1, wherein 90% or more of atomic oxygen having an emission wavelength of 750 nm is contained in the atomic oxygen contained in the atmosphere of the heat treatment.
以上７００℃以下の温度で行われる酸化物薄膜の熱処理
方法。5. The heat treatment according to claim 1, wherein the heat treatment is 300 ° C.
A heat treatment method for an oxide thin film, which is performed at a temperature of 700 ° C. or lower.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7220010A JPH0964307A (en) | 1995-08-29 | 1995-08-29 | Heat treatment method of oxide thin film |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7220010A JPH0964307A (en) | 1995-08-29 | 1995-08-29 | Heat treatment method of oxide thin film |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0964307A true JPH0964307A (en) | 1997-03-07 |
Family
ID=16744523
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7220010A Pending JPH0964307A (en) | 1995-08-29 | 1995-08-29 | Heat treatment method of oxide thin film |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0964307A (en) |
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|---|---|---|---|---|
| WO2001069665A1 (en) * | 2000-03-13 | 2001-09-20 | Tadahiro Ohmi | Method for forming dielectric film |
| JP2001261346A (en) * | 2000-03-21 | 2001-09-26 | Zenhachi Okumi | Method of producing oxide precursor and oxide |
| JP2001308295A (en) * | 2000-04-24 | 2001-11-02 | Matsushita Electric Ind Co Ltd | Method of using semiconductor storage device, semiconductor storage device and its manufacturing method |
| KR100318456B1 (en) * | 1998-06-29 | 2002-03-08 | 박종섭 | A method for forming tantalum oxide capacitor in semiconductor device |
| JP2002289597A (en) * | 2001-03-23 | 2002-10-04 | Tokyo Electron Ltd | Heat treatment device and its method |
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| US7132373B2 (en) | 2001-10-02 | 2006-11-07 | Toto Ltd. | Thin metal oxide film and process for producing the same |
| JP2008510319A (en) * | 2004-08-18 | 2008-04-03 | 東京エレクトロン株式会社 | Method and system for improving a gate dielectric stack having a high dielectric constant layer using plasma treatment |
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1995
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| KR100318456B1 (en) * | 1998-06-29 | 2002-03-08 | 박종섭 | A method for forming tantalum oxide capacitor in semiconductor device |
| US6783627B1 (en) | 2000-01-20 | 2004-08-31 | Kokusai Semiconductor Equipment Corporation | Reactor with remote plasma system and method of processing a semiconductor substrate |
| WO2001069665A1 (en) * | 2000-03-13 | 2001-09-20 | Tadahiro Ohmi | Method for forming dielectric film |
| US6669825B2 (en) | 2000-03-13 | 2003-12-30 | Tadahiro Ohmi | Method of forming a dielectric film |
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| JP2001261346A (en) * | 2000-03-21 | 2001-09-26 | Zenhachi Okumi | Method of producing oxide precursor and oxide |
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| JP2001308295A (en) * | 2000-04-24 | 2001-11-02 | Matsushita Electric Ind Co Ltd | Method of using semiconductor storage device, semiconductor storage device and its manufacturing method |
| JP2002289597A (en) * | 2001-03-23 | 2002-10-04 | Tokyo Electron Ltd | Heat treatment device and its method |
| JP4655395B2 (en) * | 2001-03-23 | 2011-03-23 | 東京エレクトロン株式会社 | Heat treatment apparatus and method |
| US7132373B2 (en) | 2001-10-02 | 2006-11-07 | Toto Ltd. | Thin metal oxide film and process for producing the same |
| KR100481311B1 (en) * | 2002-09-19 | 2005-04-07 | 최대규 | Plasma process chamber |
| KR100500852B1 (en) * | 2002-10-10 | 2005-07-12 | 최대규 | Remote plasma generator |
| JP2005039281A (en) * | 2004-07-20 | 2005-02-10 | Seiko Epson Corp | Method and equipment for manufacturing ceramics, and semiconductor device and piezoelectric element |
| JP4557144B2 (en) * | 2004-07-20 | 2010-10-06 | セイコーエプソン株式会社 | Manufacturing method of ceramics |
| JP2008510319A (en) * | 2004-08-18 | 2008-04-03 | 東京エレクトロン株式会社 | Method and system for improving a gate dielectric stack having a high dielectric constant layer using plasma treatment |
| KR100974976B1 (en) * | 2006-11-09 | 2010-08-09 | 어플라이드 머티어리얼스, 인코포레이티드 | System and method for containment shielding during pecvd deposition processes |
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