JP2004342805A - Method for forming thermal oxide film and thermal oxidation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a setting technique for thermal oxidation conditions by which a high process capability is obtained even when the atmospheric pressure changes, regarding a method for forming a thermal oxide film and a thermal oxidation device. <P>SOLUTION: An oxidation processing time to the next processing lot is determined on the basis of an atmospheric-pressure information and the result of the film thickness of the oxide film in a processing lot immediately before the same oxidation device 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

の１次式で近似することができる。
【００２４】
但し、この近似式における標本相関係数の二乗（Ｒ^２ ）は、
Ｒ^２ ＝０．５２６１
となり、この近似式に基づいて、気圧情報だけで次の熱酸化処理工程における酸化時間を決定した場合には、上述のようにばらつきが大きくなる。
【００２５】
そこで、本発明においては、単に気圧情報だけではなく、直前の処理ロットの履歴を考慮して、両者を重み付け係数ｍで重み付けして、処理対象となるｎ番目のロットの酸化時間Ｄ_ｎ を下記の式から決定する。
Ｄ_ｎ ＝ｍＤ_ｘ ＋（１−ｍ）Ｄ_ｙ
【００２６】
ここで、Ｄ_ｘ は予め測定した酸化速度−気圧依存性から算出される酸化時間、即ち、気圧情報のみから算出した酸化時間であり、狙い膜厚をＴ_ｔｇｔ とした場合、
Ｄ_ｘ ＝Ｔ_ｔｇｔ ／Ｒ_ｎ ＝Ｔ_ｔｇｔ ／（ａＰ_ｎ ＋ｂ）
で表される。
【００２７】
また、Ｄ_ｙ は直前の処理ロットの酸化膜の膜厚結果から算出される酸化時間であり、Ｒ_ｎ−１ を直近の（ｎ−１）番目のロットから処理結果から算出される酸化速度とした場合、
Ｄ_ｙ ＝Ｔ_ｔｇｔ ／Ｒ_ｎ−１
で表される。
【００２８】
次に、上記のＤ_ｎ ＝ｍＤ_ｘ ＋（１−ｍ）Ｄ_ｙ の式に基づいて、重み付け係数ｍを０．０〜１．０の間で０．０５刻みに変えて、各重み付け係数ｍに対応する酸化時間Ｄ_ｎ （ｍ）を算出する。
【００２９】
次いで、算出した酸化時間Ｄ_ｎ （ｍ）に、気圧情報を用いないで処理した場合の実際の酸化速度Ｒ_{ａｃｔｕａｌ}をかけて膜厚Ｔ_ｎ （＝Ｄ_ｎ ×Ｒ_{ａｃｔｕａｌ}）に換算し、この膜厚Ｔ_ｎ の一定期間のデータ群の平均値Ａｖｅ、標準偏差σから求めたＣ_ｐｋをｍの値０．０５刻みにプロットしたのが図３である。
なお、ｍ＝１の場合が、直前の処理結果を反映させない場合である。
【００３０】
この場合、Ｃ_ｐｋは統計的プロセス管理手法における指標の一つであるＣ_ｐｋは、データ群の平均値をＡｖｅ、標準偏差をσ、データの上限規格値をＵＳＬ（Ｕｐｐｅｒ Ｓｐｅｃ Ｌｉｍｉｔ）、下限規格値をＬＳＬ（Ｌｏｗｅｒ ＳｐｅｃＬｉｍｉｔ）とすると、Ｃ_ｐｋは（ＵＳＬ−Ａｖｅ）／（３×σ）または（Ａｖｅ−ＬＳＬ）／（３×σ）の２つの値の内の低い方の値で定義される。
【００３１】
また、Ｃ_ｐ ＝（ＵＳＬ−ＬＳＬ）／（６×σ）で表される他の指標Ｃ_ｐ は、規格の幅とデータのばらつきを比較して潜在的工程能力の指針となっているのに対して、Ｃ_ｐｋはデータの偏り（狙い値からのずれ分）も考慮しているため、実質的工程能力の指針となる。
【００３２】
また、一般に、工程能力の判定基準としては、
（１）Ｃ_ｐ ，Ｃ_ｐｋ＜１．０の場合には、工程能力不足、即ち、工程能力の改善を要する、
（２）Ｃ_ｐ ，Ｃ_ｐｋ：１．０〜１．３の場合には、現状での工程管理が必要、
（３）Ｃ_ｐ ，Ｃ_ｐｋ＞１．３の場合には、工程能力は十分と
判定される。
【００３３】
図３参照
図３においては、ｍ＝０．７においてＣ_ｐｋのピークがあり、Ｃ_ｐｋ（ｍ＝０．７）≒２．４５となり、このｍの値が使用した熱処理装置及び熱処理条件に起因する設定すべき値となり、上の式は、

で表される。
【００３４】
このｍ＝０．７において、直前の処理結果を反映させない場合、即ち、ｍ＝１におけるＣ_ｐｋ（ｍ＝１）≒１．８、及び、気圧情報を反映させな従来例におけるＣ_ｐｋ（Ａｃｔｕａｌ）≒１．６に比べても大幅に改善されている。
【００３５】
図４参照
図４は、各熱処理条件における熱酸化膜Ｃ_ｐｋを改めて比較して示した図であり、Ｃ_ｐｋ（Ａｃｔｕａｌ）との比較では５２％の改善、Ｃ_ｐｋ（ｍ＝１）との比較では９％の改善が見られる。
【００３６】
Ｃ_ｐｋは、上述のように、（ＵＳＬ−Ａｖｅ）／（３×σ）または（Ａｖｅ−ＬＳＬ）／（３×σ）の２つの値の内の低い方の値で定義されるため、平均値Ａｖｅが同程度の場合には標準偏差σが小さいほどＣ_ｐｋは大きくなるので、Ｃ_ｐｋが５２％或いは９％改善されるということは、標準偏差σそれに対応するだけ小さくなることを意味し、ばらつきが低下する。
【００３７】
なお、従来の熱酸化工程におけるＣ_ｐｋ（Ａｃｔｕａｌ）及びＣ_ｐｋ（ｍ＝１）も１．３３以上であり、一般的には十分な工程能力を有していると判断されるが、Ｃ_ｐｋはあくまで規格幅に依存する値であり、よりタイトに管理するためには、さらに高い値が必要になり、本発明はそのような要請に応えるものである。
【００３８】
したがって、熱処理装置及び熱処理条件毎に、係数ａ，ｂ及び重み付け係数ｍのパラメータ値を制御システム上に設定することにより、制御システム上で酸化時間を計算させて、拡散炉の処理レシピに設定すれば良い。
【００３９】
以上、本発明の実施の形態を説明してきたが、本発明は実施の形態に記載した構成に限られるものではなく、各種の変更が可能である。
例えば、上記の実施の形態においては、熱酸化をドライ酸化で行っているが、ドライ酸化に限られるものではなく、８００〜１２００℃の塩酸酸化工程、或いは、Ｈ_２ とＯ_２ を用いたパイロジェニック法によるウエット酸化工程にも適用されるものである。
この場合にも、Ｃ_ｐｋ（Ａｃｔｕａｌ）に比べて２０〜５０％の改善が、また、Ｃ_ｐｋ（ｍ＝１）に比べて２〜１０％の改善が期待できる。
【００４０】
また、上記の実施の形態においては、同じ熱処理装置装置における直前の同じ製品の酸化結果を用いて次の酸化時間を設定しているが、同じ熱酸化装置を用いて異なった製品Ａ，Ｂを順次製造する際に、経時的に▲１▼酸化処理Ａ→▲２▼酸化処理Ｂ→▲３▼酸化処理Ａを行った場合、▲３▼酸化処理Ａにおいては、基本的処理条件が同じである▲１▼酸化処理Ａの膜厚結果を用いれば良い。
なお、この場合、製品処理の運用にもよるが、最大１０日前までの同一条件の処理結果を用いることができるように設定する。
【００４１】
また、製品Ａと製品Ｂの熱酸化工程における酸化膜厚の差が１ｎｍ以下の場合には、基本的処理条件が近似しているので、▲３▼酸化処理Ａにおいて▲２▼酸化処理Ｂにおける膜厚結果を用いても良いものである。
【００４２】
この場合、酸化処理Ａにおける酸化速度をＲ_Ａ 、酸化処理Ｂにおける酸化速度をＲ_Ｂ とすると、
Ｒ_Ａ ＝ａ_１ ×Ｐ＋ｂ_１
Ｒ_Ｂ ＝ａ_２ ×Ｐ＋ｂ_２
の近似式で表されるが、気圧成分Ｐを消去すると、
Ｒ_Ｂ ＝（ａ_２ ／ａ_１ ）Ｒ_Ａ −（ａ_２ ／ａ_１ ）ｂ_１ ＋ｂ_２
が得られる。
この値（ａ_２ ／ａ_１ ）、−（ａ_２ ／ａ_１ ）ｂ_１ ＋ｂ_２ を変換係数として制御システム上に設定することによって、酸化処理Ｂにおける膜厚結果を次の酸化処理Ａに用いることができる。
【００４３】
また、上記の実施の形態においては、酸化時間と膜厚結果を制御システムに取り込んでいるが、工場全体を管理するオペレーションシステムに取り込んでも良く、オペレーションシステムで酸化速度を計算させて、その結果を制御システム上に取り込むようにしても良いものである。
【００４４】
ここで、再び図１を参照して、改めて本発明の詳細な特徴を説明する。
再び、図１参照
（付記１） 気圧情報と同一酸化装置１の直前の処理ロットの酸化膜の膜厚結果に基づいて、次の処理ロットに対して酸化処理時間を決定することを特徴とする熱酸化膜の形成方法。
（付記２） 上記直前の処理ロットの製品が、上記次の処理ロットの製品と同一製品であることを特徴とする付記１記載の熱酸化膜の形成方法。
（付記３） 上記直前の処理ロットの製品が、上記次の処理ロットの製品と酸化膜厚の差が１ｎｍ以下異なった製品であることを特徴とする付記１記載の熱酸化膜の形成方法。
（付記４） 上記酸化処理時間をＤ_ｎ とし、Ｄ_ｘ を予め測定した酸化速度−気圧依存性から算出される酸化時間とし、Ｄ_ｙ を直前の処理ロットの酸化膜の膜厚結果から算出される酸化時間とし、また、ｍ（＞０）を重み付け係数とした場合に、 Ｄ_ｎ ＝ｍＤ_ｘ ＋（１−ｍ）Ｄ_ｙ
で設定することを特徴とする付記１乃至３のいずれか１に記載の熱酸化膜の形成方法。
（付記５） 上記重み付け係数ｍを変動した場合に最大の酸化膜厚Ｃ_ｐｋが得られる重み付け係数ｍの値で酸化処理時間Ｄ_ｎ を決定することを特徴とする付記４記載の熱酸化膜の形成方法。
（付記６） 気圧情報と同一酸化装置１の直前の処理ロットの酸化膜の膜厚結果に基づいて、次の処理ロットに対して酸化処理時間を決定する機能を備えたことを特徴とする熱酸化装置。
【００４５】
【発明の効果】
本発明によれば、気圧情報だけではなく、直前の酸化処理工程の膜厚結果も反映して次の熱処理工程における酸化時間を決定しているので、高い工程能力を有する酸化工程を実現することができ、それによって、プロセスの安定性を確保することができ、ひいては、半導体集積回路装置の信頼性の向上或いは製造歩留の向上に寄与するところが大きい。
【図面の簡単な説明】
【図１】本発明の原理的構成の説明図である。
【図２】酸化速度の気圧依存性の説明図である。
【図３】熱酸化膜Ｃ_ｐｋの重み付け係数ｍ依存性の説明図である。
【図４】各熱処理条件における熱酸化膜Ｃ_ｐｋの比較図である。
【符号の説明】
１ 酸化装置
２ 気圧計
３ 膜厚計測装置
４ 制御装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thermal oxide film forming method and a thermal oxidizing apparatus, and more particularly to a thermal oxide film forming method and a thermal oxidizing apparatus characterized by a method for preventing a variation in an oxide film thickness due to a variation in atmospheric pressure. It is about.
[0002]
[Prior art]
In the manufacturing process of semiconductor devices, the process of forming a thermal oxide film constitutes an important manufacturing process.However, conventionally, in the process of forming a thermal oxide film using a diffusion furnace, temperature and gas flow are controlled at normal pressure. Then, the thickness of the thermal oxide film is determined by the oxidation time.
[0003]
However, it is known that the formation of the thermal oxide film under normal pressure is affected by the variation of the thermal oxide film thickness and the atmospheric pressure. The film thickness increases with increasing atmospheric pressure.
[0004]
As described above, when the thickness of the thermal oxide film varies, there is a problem that various device characteristics are affected. Therefore, how to suppress the film thickness variation is a problem in manufacturing for maintaining the device characteristics. Has become.
[0005]
In particular, when the thickness of a thin film that affects data erasing characteristics of a device such as a tunnel oxide film in a memory cell portion or a gate oxide film of a peripheral transistor in a flash memory structure varies, there is a problem that data erasing time varies.
Incidentally, the thickness of the tunnel oxide film has a correlation with the data erase time (Erase Time), and when the thickness changes by 1 °, the thickness changes by about 5 ms.
[0006]
Therefore, it has been proposed to control the thickness of the thermal oxide film by calculating the oxidation time from the atmospheric pressure information so that the thickness of the thermal oxide film becomes a target value (for example, see Patent Document 1).
[0007]
It has also been proposed that an atmospheric pressure controller (APC: Auto Pressure Controller) monitors the external pressure with a barometer and adjusts the degree of opening and closing of the exhaust line to keep the pressure in the chamber constant. (For example, see Patent Document 2).
[0008]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 05-032500 [Patent Document 2]
JP-A-10-223622
[Problems to be solved by the invention]
However, the above-mentioned Patent Document 1 merely presents a conceptual method, and it is unclear what method and conversion formula are used to specifically control the oxidation conditions. Is unknown.
[0010]
Further, even if the oxidation time is controlled from the atmospheric pressure information, the _Cpk, which is an index of the statistic in the statistical process control method (SPC), is not always sufficient, and a high process capability cannot be obtained. is there.
[0011]
In Patent Document 2 described above, although a certain improvement effect can be expected, it is difficult to precisely control the pressure in the chamber to a constant level. There is also a problem that the controllability of the obtained oxide film thickness is not sufficient because of the dependence.
[0012]
Accordingly, an object of the present invention is to provide a method for setting thermal oxidation conditions that can provide high process capability even when the atmospheric pressure fluctuates.
[0013]
[Means for Solving the Problems]
FIG. 1 is an explanatory diagram of the basic configuration of the present invention. Here, means for solving the problem in the present invention will be described with reference to FIG.
Note that reference numeral 4 in the figure denotes a control device.
Referring to FIG. 1, in order to achieve the above object, the present invention relates to a method for forming a thermal oxide film, the method comprising the steps of: On the other hand, the oxidation treatment time is determined.
[0014]
As described above, in the thermal oxidation process, the oxidation processing time is determined by using the pressure information acquired by the barometer 2 and the result of the thickness of the oxide film of the processing lot immediately before the same oxidizing apparatus 1, so that the oxide film thickness can be reduced. It is possible to obtain a result reflecting the dependency on the cumulative number of processed lots, thereby obtaining a higher process capability than simply reflecting pressure information.
[0015]
In this case, it is desirable to use the same product as the product of the next thermal oxidation step as the product of the immediately preceding processing lot.
That is, when (1) oxidation treatment A → (2) oxidation treatment B → (3) oxidation treatment A is performed with time in the same oxidizing apparatus 1, (3) oxidation treatment A requires basic treatment conditions. By using the same (1) film thickness result of the oxidation treatment A, the oxidation treatment with less variation can be performed.
[0016]
Alternatively, if the product of the immediately preceding processing lot is a product having a difference in oxide film thickness of 1 nm or less from the product to be subjected to the next thermal oxidation step, the film thickness result in this processing lot may be used. It is.
That is, when (1) oxidation treatment A → (2) oxidation treatment B → (3) oxidation treatment A is performed with time in the same oxidation apparatus 1, (3) oxidation treatment A, the basic treatment conditions are similar. In this case, good results can be obtained by using the results of (2) the thickness of the oxidation treatment B.
[0017]
In the above case, the oxidation treatment time is D _n, the oxidation rate was measured in advance D _x - and oxidation time calculated from the pressure-dependent, measured by the thickness measuring apparatus 3 of the oxide film immediately before the processing lots D _y When the oxidation time is calculated from the film thickness result obtained, and m (> 0) is used as a weighting coefficient,
_{D n = mD x + (1} -m) D y
It is desirable to set with.
[0018]
In particular, it is desirable to determine the biggest oxide thickness C value of _pk weighting coefficient m obtained when varying weighting coefficient m oxidation treatment time D _n, whereby it is possible to obtain a high process capability.
[0019]
Further, it is preferable that the thermal oxidation apparatus has a function of determining an oxidation processing time for the next processing lot based on the atmospheric pressure information and the thickness result of the oxide film of the processing lot immediately before the same oxidation apparatus 1. .
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Here, a thermal oxidation method according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 2 is an explanatory diagram of the atmospheric pressure dependence of the oxidation rate. Here, in the case of a dry oxidation step at 950 ° C. using Ar as a carrier gas and O ₂ and HCl as oxidizing gases. The results are shown.
[0021]
In this case, each data plots the correlation between the atmospheric pressure immediately after the start of processing of one batch on the apparatus (within 10 minutes) and the oxidation rate obtained from the result of the film thickness measured after the processing and the oxidation time. The oxidation rate at one point represents the average value of the film thickness results of one batch.
[0022]
The pressure data is a diffusion furnace for oxidation, that is, a barometer installed near the heat treatment furnace, and constantly takes an average value, for example, every 10 minutes. The results are captured in the control system.
Alternatively, if there is a barometer attached to the diffusion furnace equipment, the value of the barometric pressure data may be monitored.
[0023]
As shown in the figure, the dependence of the oxidation rate R _n [Å / min] on the atmospheric pressure P _n [kPa] is obtained when a and b are coefficients caused by the processing apparatus and processing conditions.

Can be approximated by the following linear expression.
[0024]
However, the square (R ² ) of the sample correlation coefficient in this approximate expression is
R ² = 0.5261
When the oxidation time in the next thermal oxidation process is determined based only on the atmospheric pressure information based on this approximate expression, the variation becomes large as described above.
[0025]
Therefore, in the present invention, in consideration of not only the atmospheric pressure information but also the history of the immediately preceding processing lot, both are weighted by the weighting coefficient m, and the oxidation time D _n of the n-th lot to be processed is calculated as follows. Is determined from the following equation.
_{D n = mD x + (1} -m) D y
[0026]
Here, _Dx is an oxidation time calculated from the previously measured oxidation rate-pressure dependency, that is, an oxidation time calculated only from the pressure information, and when the target film thickness is T _tgt ,
_{D x = T tgt / R n} = T tgt / (aP n + b)
Is represented by
[0027]
Further, D _y is the oxidation time calculated from the membrane thickness results of the oxide film immediately before the processed lot, the oxidation rate calculated from the processing result R _n-1 from the last (n-1) -th lot if you did this,
_{D y = T tgt / R n} -1
Is represented by
[0028]
Next, based on the above equation of _{D n = mD x + (1} -m) D y, instead of increments of 0.05 weighting factor m between 0.0 and 1.0, the weighting factor m The oxidation time D _n (m) corresponding to is calculated.
[0029]
Next, the calculated oxidation time D _n (m) is _multiplied by the _actual oxidation rate R _actual when the treatment is performed without using the atmospheric pressure information, and converted into a film thickness T _n (= D _n × R _actual ). the average value of the data group for a certain period of thickness T _n Ave, that the C _pk determined from the standard deviation σ is plotted the value 0.05 increments of m is 3.
Note that the case where m = 1 is the case where the immediately preceding processing result is not reflected.
[0030]
In this case, _Cpk is one of the indexes in the statistical process management method. _Cpk is Ave for the average value of the data group, σ for the standard deviation, USL (Upper Spec Limit) for the upper limit of the data, and lower limit for the data group. a value of the LSL (lower _{SpecLimit), C pk} is defined at the lower value of the two values (USL-Ave) / (3 × σ) or (Ave-LSL) / (3 × σ) You.
[0031]
Another indicator C _p represented by _{C p = (USL-LSL)} / (6 × σ) is to have a guide of potential process capability by comparing the variation in the width and data standards On the other hand, since _Cpk also considers the bias of data (the deviation from the target value), it serves as a guide for the substantial process capability.
[0032]
Also, generally, as a criterion of the process capability,
(1) When C _p and C _pk <1.0, the process capability is insufficient, that is, the process capability needs to be improved.
_{(2) C p, C pk} : in the case of 1.0 to 1.3, the required process control at present,
(3) If C _p , C _pk > 1.3, the process capability is determined to be sufficient.
[0033]
Referring to FIG. 3, there is a peak of C _{pk at} m = 0.7, and C _pk (m = 0.7) ≒ 2.45. This value of m is caused by the heat treatment apparatus and heat treatment conditions used. And the above equation is

Is represented by
[0034]
At m = 0.7, when the immediately preceding processing result is not reflected, that is, C _pk (m = 1) ≒ 1.8 at m = 1, and C _pk (Actual) in the conventional example in which the pressure information is not reflected. ) It is also greatly improved compared to $ 1.6.
[0035]
FIG. 4 is a diagram again showing the thermal oxide film C _pk under each heat treatment condition. In comparison with C _pk (Actual), the thermal oxide film C _pk is improved by 52%, and C _pk (m = 1). A comparison shows a 9% improvement.
[0036]
As described above, C _pk is defined by the lower value of the two values of (USL-Ave) / (3 × σ) or (Ave-LSL) / (3 × σ), so that the average When the value Ave is approximately the same, the smaller the standard deviation σ, the larger the _Cpk becomes. Therefore, an improvement in _Cpk of 52% or 9% means that the standard deviation σ becomes smaller correspondingly. , The variation is reduced.
[0037]
Incidentally, _C pk in the conventional thermal oxidation process (Actual) and _C pk (m = 1) is also 1.33 or more, but it is determined that generally have sufficient process _{capability, C pk} Is a value that depends only on the standard width, and a higher value is required for tighter management, and the present invention meets such a demand.
[0038]
Therefore, by setting the parameter values of the coefficients a and b and the weighting coefficient m on the control system for each heat treatment apparatus and heat treatment condition, the oxidation time is calculated on the control system and set in the treatment recipe of the diffusion furnace. Good.
[0039]
The embodiments of the present invention have been described above, but the present invention is not limited to the configurations described in the embodiments, and various modifications are possible.
For example, in the above embodiment, the thermal oxidation is performed by dry oxidation, but the thermal oxidation is not limited to dry oxidation, and is performed by a hydrochloric acid oxidation process at 800 to 1200 ° C. or a pyrolysis using H ₂ and O _2. The present invention is also applied to a wet oxidation process using a genic method.
Also in this case, an improvement of 20 to 50% as compared with C _pk (Actual) and an improvement of 2 to 10% as compared with C _pk (m = 1) can be expected.
[0040]
Further, in the above-described embodiment, the next oxidation time is set using the oxidation result of the immediately preceding same product in the same heat treatment apparatus, but different products A and B are set using the same thermal oxidation apparatus. When sequentially performing (1) oxidation treatment A → (2) oxidation treatment B → (3) oxidation treatment A during sequential production, (3) oxidation treatment A has the same basic treatment conditions. It is sufficient to use the result of the film thickness of the oxidation treatment A.
In this case, although it depends on the operation of the product processing, the setting is made so that the processing results under the same condition up to 10 days before can be used.
[0041]
Further, when the difference in the oxide film thickness in the thermal oxidation step between the product A and the product B is 1 nm or less, the basic processing conditions are similar, so that (3) in the oxidation treatment A and (2) in the oxidation treatment B The result of the film thickness may be used.
[0042]
In this case, the oxidation rate in the oxidation process A R _A, the oxidation rate in the oxidation process B When R _B,
R _A = a ₁ × P + b ₁
R _B = a ₂ × P + b ₂
However, when the pressure component P is eliminated,
_{R B = (a 2 / a} 1) R A - (a 2 / a 1) b 1 + b 2
Is obtained.
By setting these values (a ₂ / a ₁ ) and − (a ₂ / a ₁ ) b ₁ + b ₂ on the control system as conversion coefficients, the film thickness result in the oxidation processing B is used for the next oxidation processing A. be able to.
[0043]
In the above embodiment, the oxidation time and the film thickness result are taken into the control system. However, the oxidation time and the film thickness result may be taken into the operation system that manages the entire factory, and the operation system calculates the oxidation rate, and the result is calculated. It may be taken in on the control system.
[0044]
Here, referring to FIG. 1 again, the detailed features of the present invention will be described again.
Again referring to FIG. 1 (Appendix 1), the oxidation processing time is determined for the next processing lot based on the atmospheric pressure information and the oxide film thickness result of the processing lot immediately before the same oxidizing apparatus 1. A method for forming a thermal oxide film.
(Supplementary Note 2) The method for forming a thermal oxide film according to Supplementary Note 1, wherein the product of the immediately preceding processing lot is the same product as the product of the next processing lot.
(Supplementary Note 3) The method for forming a thermal oxide film according to Supplementary Note 1, wherein the product of the immediately preceding processing lot is a product having a difference in oxide film thickness of 1 nm or less from the product of the next processing lot.
(Supplementary Note 4) The above oxidation treatment time is D _n, the oxidation rate was measured in advance D _x - and oxidation time calculated from the pressure-dependent, is calculated D _y from the thickness results of the oxide film immediately before the processed lot oxidation time and to that, also in the case of the weighting coefficients _{m (> 0), D n} = mD x + (1-m) D y
4. The method for forming a thermal oxide film according to any one of supplementary notes 1 to 3, wherein:
(Supplementary Note 5) of the thermal oxide film of Supplementary Note 4, wherein the determining the value in the oxidation treatment time D _n of the weighting coefficients m weighting coefficients maximum oxide thickness C _pk is obtained when varying m Forming method.
(Supplementary Note 6) A heat treatment apparatus having a function of determining an oxidation treatment time for the next treatment lot based on the atmospheric pressure information and the result of the thickness of the oxide film of the treatment lot immediately before the same oxidation apparatus 1. Oxidation equipment.
[0045]
【The invention's effect】
According to the present invention, since the oxidation time in the next heat treatment step is determined by reflecting not only the atmospheric pressure information but also the thickness result of the immediately preceding oxidation treatment step, it is possible to realize an oxidation step having high process capability. Thus, the stability of the process can be ensured, and this greatly contributes to the improvement of the reliability or the manufacturing yield of the semiconductor integrated circuit device.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a basic configuration of the present invention.
FIG. 2 is an explanatory diagram of the atmospheric pressure dependence of an oxidation rate.
FIG. 3 is an explanatory diagram of the dependency of a thermal oxide film _{Cpk on} a weighting coefficient m.
FIG. 4 is a comparison diagram of a thermal oxide film _Cpk under each heat treatment condition.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Oxidation apparatus 2 Barometer 3 Film thickness measuring device 4 Control device

Claims (5)

A method for forming a thermal oxide film, comprising determining an oxidation processing time for a next processing lot based on pressure information and a result of an oxide film thickness of a processing lot immediately before the same oxidizing apparatus. 2. The thermal oxide film forming method according to claim 1, wherein the product of the immediately preceding processing lot is the same product as the product of the next processing lot. 2. The method according to claim 1, wherein the product of the immediately preceding processing lot is a product having a difference in oxide film thickness of 1 nm or less from the product of the next processing lot. The oxidation time is D _n, the oxidation rate was measured in advance D _x - and oxidation time calculated from the pressure-dependent, and oxidation time to be calculated D _y from the thickness results of the oxide film immediately before the processed lot , And m (> 0) as a weighting factor,
_{D n = mD x + (1} -m) D y
The method for forming a thermal oxide film according to claim 1, wherein: A thermal oxidation apparatus having a function of determining an oxidation processing time for a next processing lot based on atmospheric pressure information and a thickness result of an oxide film of a processing lot immediately before the same oxidation apparatus.

Images