JP2004072022A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device, which is capable of reducing the number of conditioning process for obtaining the set temperature of a heater through dummy-less processing. <P>SOLUTION: The method of manufacturing a semiconductor device comprises a first process of carrying out batch processing of a plurality of times as the number n of processing substrates is varied and obtaining a relation between lnx and 1/y in each batch processing when thickness uniformity is below a reference value, wherein y denotes a temperature at an optional position x in the direction of a gas flow in an oven; a second process of obtaining a first approximate expression linearly approximating the relation between lnx and 1/y; a third process of obtaining a relation between the tilt a<SB>1</SB>of the first approximate expression and the number n of the processing substrates and a relation between the intercept b<SB>1</SB>of the first approximate expression and the number of processing substrates; a fourth process of obtaining a second and a third approximate expression linearly approximating the above relations; a fifth process of obtaining a relation between x and y on the basis of the first to the third approximate expression when the number of processing substrates is represented by n and obtaining a furnace temperature gradient; a sixth process of calculating a set temperature of each heater zone. so as to form a furnace temperature gradient; and a seventh process of setting the temperature of each heater zone to the calculated set temperature and carrying out batch processing. <P>COPYRIGHT: (C)2004,JPO

Description

ここで、ａ_ｘ、ｂ_ｘ、ｃ_ｘ、ｄ_ｘ、ｅ_ｘは、Ｔ_Ｕｃ、Ｔ_ＣＵｃ、Ｔ_Ｃｃ、Ｔ_ＣＬｃ、Ｔ_Ｌｃの温度を１℃変化させたときの位置ｘにおける温度変化である。すなわち、炉内温度は制御温度を用いて次式（２）のようにして表すことができる。
【００１５】
【数２】

【００１６】
最下部を基準としたボートスロットのモニタ位置１６７、１４１、１１５、８９、６３、３７、１１の炉内の温度を求める干渉行列は、７×５の行列となり、１５０枚処理時のモニタ位置での温度は図７のようになる。同様に、１００枚、５０枚処理時のモニタ位置の温度も図７に示す。
【００１７】
ここで、モニタウェハの位置（ボートスロット）をｘ、その部分の温度をｙ（絶対温度）としたとき、ｌｎｘ対１／ｙでプロットすると、図８に示したようになる。これを直線で近似し、傾きをａ_１、切片をｂ_１とすると、それぞれの処理枚数において、ａ_１、ｂ_１の値は図９となる。
【００１８】
次に、このａ_１、ｂ_１を処理枚数の関数としてプロットすると図１０となり、これを直線近似したときの係数をａ_ａ１、ｂ_ａ１およびａ_ｂ１、ｂ_ｂ１とする。すなわち、プロダクト７５枚を処理する場合の係数ａ_１、ｂ_１は、ａ_１＝７５×ａ_ａ１＋ｂ_ａ１、ｂ_１＝７５×ａ_ｂ１＋ｂ_ｂ１によって求められる。したがって、このとき、炉内温度の傾斜は、ｙ＝ａ_１×ｌｎｘ＋ｂ_１にそれぞれのモニタ位置を入力することよって計算できる。具体的には、図８および図１０に示すような結果があると、７５枚処理時には図１１のような温度傾斜となる。
【００１９】
一方、炉内温度を制御温度へ変換する際には、転置行列Ｍｔを用いて次式（３）により変換を行う。
【数３】

図１１の温度傾斜を用いた場合、式（３）を用いて計算した設定温度は図１２になる。この温度傾斜を用いて実際に成膜を行うと、モニタウェハ膜厚の面間均一性が１．４％となった。
【００２０】
以上説明した本発明における半導体装置の製造方法を要約すると次の通りである。本発明における半導体装置の製造方法は、複数のゾーンに分割されたヒータを有する反応炉内でｎ枚の基板をボートに支持し、ガス流上流側に詰めた状態で加熱してバッチ処理する工程を有する半導体装置の製造方法であって、
炉内のガス流方向の任意位置（ガス流の最上流にあるスロットを基準としたボートスロット位置）ｘにおける炉内温度をｙとし、処理枚数ｎを変化させて（１５０枚、１００枚、５０枚）複数回バッチ処理し、膜厚均一性が基準値以下（１％以下）となったときのそれぞれのバッチ処理におけるｌｎｘと１／ｙとの関係を求める工程と（図８参照）、
前記ｌｎｘと１／ｙとの関係を直線で近似し、第１の近似式（ｌｎｘ＝ａ_１×１／ｙ＋ｂ_１）を得る工程と（図８、図９参照）、
第１の近似式の傾きａ_１と処理枚数ｎとの関係、および第１の近似式の切片ｂ_１と処理枚数ｎとの関係を求める工程と（図１０参照）、
前記第１の近似式の傾きａ_１と処理枚数ｎとの関係、および第１の近似式の切片ｂ_１と処理枚数ｎとの関係を直線で近似し、第２の近似式（ａ_１＝ａ_ａ１×ｎ＋ｂ_ａ１）および第３の近似式（ｂ_１＝ａ_ｂ１×ｎ＋ｂ_ｂ１）を得る工程と、
前記第１〜３の近似式により、処理枚数をｎとしたときの炉内の任意位置ｘと炉内温度ｙとの関係を求め、処理枚数をｎとしたときの炉内温度傾斜を求める工程と、
前記炉内温度傾斜を形成するよう各ヒータゾーンの設定温度を算出する工程と（ここで干渉行列を用いる）、
各ヒータゾーンの温度を、前記算出した設定温度に設定して前記反応炉内でｎ枚の基板をバッチ処理する工程と
を有する。
【００２１】
また、各ヒータゾーンの設定温度を変化させたときの炉内の任意位置における温度変化量を求めて行列Ｍを得る工程を有し、前記各ヒータゾーンの設定温度を算出する工程では、この行列Ｍを用いて前記炉内温度傾斜を形成するような各ヒータゾーンの設定温度を算出する。
【００２２】
【発明の効果】
したがって、本発明によれば、フィルダミーウェハを用いず処理を行うことができ、ヒータの設定温度を求めるための条件出し回数を低減することができる。また、フィルダミーに要するコストが必要なくなるだけでなく、ウェハ搬送時間を従来と比較して短縮することもできる。
【図面の簡単な説明】
【図１】本発明に実施の形態に係る反応炉を示す構成図である。
【図２】図１のヒータ１とカスケード制御ＴＣ７の位置関係を示す図である。
【図３】ボート上のフルチャージ時のウェハ配置を示す図である。
【図４】フルチャージで１５０枚のウェハを処理できるボートを用いて１００枚のウェハを処理する場合のウェハ配置を示す図である。
【図５】ＳｉＮの成膜をフルチャージ１５０枚、ダミーレス１００枚、ダミーレス５０枚のウェハで行い、ウェハ間の膜厚均一性を合わせたときのウェハ配置を示す図である。
【図６】面間均一性１％以下となったときの設定温度の説明図である。
【図７】面間均一性１％以下となったときのモニタウェハ位置における炉内温度の説明図である。
【図８】モニタ位置ｘと炉内温度ｙの関係を示す図である。
【図９】各処理枚数における傾きと切片の説明図である。
【図１０】処理枚数と係数ａ_１，ｂ_１の関係を示す図である。
【図１１】７５枚処理時の炉内温度計算結果を示す図である。
【図１２】干渉行列を用いた炉内温度から設定温度への変換の説明図である。
【符号の説明】
１　５ゾーン分割ヒータ
２　アウターチューブ
３　インナーチューブ
４　ウェハ
５　ボート
６　断熱板
７　カスケード制御ＴＣ
８　プロファイルＴＣ
９　ノズル
１０　排気口
１１　サイドダミーウェハ
１２　プロダクトウェハ
１３　モニタウェハ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a dummyless process in a vertical batch type device.
[0002]
[Prior art]
In the current CVD process, when the number of product wafers is less than a specified number, a fill dummy wafer is inserted to cope with the problem. When a fill dummy wafer is not used, the uniformity of film thickness between wafers in a batch is reduced due to the effect of a space region where no wafer exists. Specifically, the film thickness of the monitor wafer in the portion closest to the space is greatly increased as compared with the state using the fill dummy wafer. In order to control this, a method of holding the product wafer in the state of being brought to the upstream side in the flow direction of the processing gas, placing a dummy wafer immediately downstream, and lowering the set temperature of the heater entering the monitor area closest to the space is used. Has been taken.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional method for manufacturing a semiconductor device, since processing is performed using a fill dummy wafer, there has been a problem in that obtaining a set temperature of a heater becomes complicated.
[0004]
SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and can perform processing without using a fill dummy wafer, and can reduce the number of conditions for obtaining a set temperature of a heater. It is an object of the present invention to provide a method for manufacturing a semiconductor device having the following features.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in a method for manufacturing a semiconductor device according to the present invention, n substrates are supported on a boat in a reactor having a heater divided into a plurality of zones, and are packed on a gas flow upstream side. A method of manufacturing a semiconductor device having a step of performing batch processing by heating in a state, wherein the furnace temperature at an arbitrary position x in the gas flow direction in the furnace is set to y, and the number n of processed wafers is changed to perform batch processing a plurality of times. Obtaining the relationship between lnx and 1 / y in each batch process when the film thickness uniformity is equal to or less than the reference value, and approximating the relationship between lnx and 1 / y with a straight line, The step of obtaining the approximate expression (lnx = a ₁ × 1 / y + b ₁ ), the relationship between the slope a _{1 of} the first approximate expression and the number of processed sheets n, and the intercept b ₁ and the number of processed sheets n of the _first approximate expression treatment and process, the gradient a ₁ in the first approximation formula for obtaining the relationship Relationship between the number n, and a first approximation equation relationship between the intercept _{b 1} and the processing number n of approximated by a straight line, the second approximation formula _{(a 1 = a a1 × n} + b a1) and the third approximate expression (B ₁ = a _b1 × n + b _b1 ) and the relationship between an arbitrary position x in the furnace and the temperature y in the furnace when the number of substrates to be processed is n is determined by the first to third approximate expressions. Calculating the furnace temperature gradient when the number of processed sheets is n; calculating the set temperature of each heater zone so as to form the furnace temperature gradient; and calculating the temperature of each heater zone. Setting a set temperature and batch-processing n substrates in the reaction furnace.
[0006]
According to this configuration, the processing can be performed without using the fill dummy wafer, and the number of conditions for obtaining the set temperature of the heater can be reduced.
[0007]
In the above configuration, a step of obtaining a matrix M by obtaining a temperature change amount at an arbitrary position in the furnace when the set temperature of each heater zone is changed, and calculating the set temperature of each heater zone Then, the set temperature of each heater zone that forms the furnace temperature gradient can be calculated using the matrix M.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1 is a configuration diagram illustrating a reactor according to an embodiment of the present invention. The reaction chamber shown in FIG. 1 is heated by a heater 1 divided into five zones U, CU, C, CL, and L. The reaction chamber has an inner tube 3 inside the outer tube 2 and a boat 5 on which a plurality of wafers 4 can be loaded inside the inner tube 3. A heat insulating plate 6 can be held below the boat 5. Further, it has five pairs of cascade control TC7 for furnace temperature control and a removable profile TC8 which can measure the furnace temperature distribution continuously.
[0009]
The gas is supplied from the nozzle 9, passes through the inside of the inner tube 3, and is discharged from the upper part of the inner tube 3 through the space between the inner tube 3 and the outer tube 2 from the exhaust port 10. The positional relationship between the heater 1 and the cascade control TC7 is as shown in FIG. 2, and the positions of the cascade control TC7 are Uc, CUc, Cc, CLc and Lc from the top.
[0010]
Wafer processing is performed according to the following procedure. The wafer 4 loaded on the boat 5 is charged into the reaction chamber, and the pressure in the reaction chamber is reduced. After sufficiently reducing the pressure, the reaction chamber is purged with nitrogen and stabilized at a predetermined pressure. After the temperature and pressure are sufficiently stabilized, a process gas is supplied to form a film. When the film formation is completed, the pressure is returned to the atmospheric pressure while supplying nitrogen to the reaction chamber, and the boat 5 is lowered. After the wafer 4 is cooled, it is collected.
[0011]
As shown in FIG. 3, the wafers on the boat 5 are arranged such that the product wafer 12 is sandwiched between the side dummy wafers 11, and the monitor wafer 13 is inserted into an arbitrary position of the product wafer 12. These are held in a state of being brought to the upstream side in the flow direction of the processing gas. For example, when processing 100 wafers using a boat 5 capable of processing 150 wafers at full charge, as shown in FIG. 4, the wafer is held in a state of being packed upstream of the gas flow.
[0012]
Actually, the SiN film is formed on 150 wafers of full charge, 100 wafers of dummyless, and 50 wafers of dummyless, and the wafer arrangement when the film thickness uniformity between wafers is matched is as shown in FIG. Five dummy wafers 11 were placed above the product wafer 12, ten were placed below the product wafer 12, and one monitor wafer 13 was placed for every 25 product wafers. The set temperature when the uniformity of the film forming speed of the monitor wafer 13 in each process became 1% or less was as shown in FIG. An interference matrix is used to convert the set temperature into the temperature at each monitor position.
[0013]
The following measurements were made to create an interference matrix. First, the inside of the furnace is set to a reference temperature and, after sufficiently stabilized, the profile TC8 is lowered at a constant speed to measure the temperature distribution in the furnace. After that, in each zone, after the temperature is raised to an arbitrary temperature and stabilized, the furnace temperature is measured again by the profile TC8. Thus, a continuous temperature distribution in the furnace when each zone is set to + 1 ° C. is obtained. The moving distance of the auto profiler converted into slot positions of the boat, by defining it as interference matrix M, setting the temperature _{T x} at the furnace position x point cascade control TC7 temperature _{T Uc, T CUc, T Cc} , Using T _CLc and T _Lc and the reference temperature T ₀ , it can be expressed as the following equation (1).
[0014]
(Equation 1)

_Here, a _{x, b} x, c _x, d x, _{e x is} the temperature change at the position x when the _{T Uc, T CUc, T Cc} , T CLc, the temperature of _{T Lc} is 1 ℃ changed . That is, the furnace temperature can be represented by the following equation (2) using the control temperature.
[0015]
(Equation 2)

[0016]
The interference matrix for calculating the temperature in the furnace at the monitor positions 167, 141, 115, 89, 63, 37, and 11 of the boat slots with respect to the bottom is a 7 × 5 matrix. Is as shown in FIG. Similarly, FIG. 7 also shows the temperature at the monitor position when processing 100 sheets and 50 sheets.
[0017]
Here, assuming that the position of the monitor wafer (boat slot) is x and the temperature of that portion is y (absolute temperature), plotting lnx vs. 1 / y is as shown in FIG. If this is approximated by a straight line and the slope is a ₁ and the intercept is b ₁ , the values of a ₁ and b ₁ for each number of processed sheets are as shown in FIG.
[0018]
Then, next to FIG. 10 A plot of this _a 1, _{b 1} as a function of the processed sheets, which the modulus of linear approximation to _{a a1, b a1} and _{a b1, b b1.} That is, the coefficients a ₁ and b ₁ when processing 75 products are obtained from a ₁ = 75 × a _a1 + b _a1 and b ₁ = 75 × a _b1 + b _b1 . Accordingly, at this time, the inclination of the furnace temperature can be calculated by inputting each monitor position to y = a ₁ × lnx + b ₁ . Specifically, if there are the results shown in FIGS. 8 and 10, the temperature gradient will be as shown in FIG. 11 when 75 sheets are processed.
[0019]
On the other hand, when converting the in-furnace temperature into the control temperature, the conversion is performed by the following equation (3) using the transposed matrix Mt.
[Equation 3]

When the temperature gradient shown in FIG. 11 is used, the set temperature calculated using Expression (3) is as shown in FIG. When film formation was actually performed using this temperature gradient, the inter-surface uniformity of the monitor wafer film thickness was 1.4%.
[0020]
The manufacturing method of the semiconductor device according to the present invention described above is summarized as follows. A method of manufacturing a semiconductor device according to the present invention includes a step of supporting n substrates on a boat in a reaction furnace having a heater divided into a plurality of zones, and heating and batch-treating the substrate in a state where the substrate is packed upstream of a gas flow. A method for manufacturing a semiconductor device having
The temperature in the furnace at an arbitrary position in the gas flow direction in the furnace (boat slot position with reference to the slot at the uppermost stream of the gas flow) x is set to y, and the number n of processed wafers is changed (150, 100, 50 (B) a plurality of batch processes, and a process of obtaining the relationship between lnx and 1 / y in each batch process when the film thickness uniformity is equal to or less than a reference value (1% or less) (see FIG. 8);
A process of approximating the relationship between lnx and 1 / y with a straight line to obtain a _first approximation formula (lnx = a ₁ × 1 / y + b ₁ ) (see FIGS. 8 and 9);
Obtaining a relationship between the slope a ₁ of the first approximate expression and the number n of processed sheets and a relationship between the intercept b ₁ of the first approximate expression and the number n of processed sheets (see FIG. 10);
Said first approximate equation relationship between the gradient a ₁ and the processing number n, and a first approximation equation relationship between the intercept b ₁ and the processing number n of approximated by a straight line, the second approximation formula (a ₁ = a _a1 × n + b _a1 ) and a third approximate expression (b ₁ = a _b1 × n + b _b1 );
A step of obtaining a relationship between an arbitrary position x in the furnace and a furnace temperature y when the number of processed pieces is n and a furnace temperature gradient when the number of processed pieces is n by the first to third approximate expressions When,
Calculating a set temperature of each heater zone to form the furnace temperature gradient (using an interference matrix here);
Setting the temperature of each heater zone to the calculated set temperature and batch processing n substrates in the reaction furnace.
[0021]
In addition, the method includes a step of obtaining a matrix M by calculating a temperature change amount at an arbitrary position in the furnace when the set temperature of each heater zone is changed, and calculating the set temperature of each heater zone by using the matrix Using M, the set temperature of each heater zone that forms the furnace temperature gradient is calculated.
[0022]
【The invention's effect】
Therefore, according to the present invention, processing can be performed without using a fill dummy wafer, and the number of conditions for obtaining the set temperature of the heater can be reduced. Further, not only is the cost required for the fill dummy unnecessary, but also the wafer transfer time can be reduced as compared with the conventional case.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a reactor according to an embodiment of the present invention.
FIG. 2 is a diagram showing a positional relationship between a heater 1 and a cascade control TC7 in FIG.
FIG. 3 is a diagram showing a wafer arrangement when a boat is fully charged.
FIG. 4 is a diagram showing a wafer arrangement when processing 100 wafers using a boat capable of processing 150 wafers with full charge.
FIG. 5 is a diagram showing a wafer arrangement when the film formation of SiN is performed on 150 wafers of full charge, 100 dummyless wafers, and 50 dummyless wafers, and the film thickness uniformity between the wafers is adjusted.
FIG. 6 is an explanatory diagram of a set temperature when the inter-surface uniformity is 1% or less.
FIG. 7 is an explanatory diagram of a furnace temperature at a monitor wafer position when the inter-plane uniformity is 1% or less.
FIG. 8 is a diagram showing a relationship between a monitor position x and a furnace temperature y.
FIG. 9 is an explanatory diagram of a slope and an intercept for each number of processed sheets.
FIG. 10 is a diagram showing a relationship between the number of processed sheets and coefficients a ₁ and b ₁ .
FIG. 11 is a diagram showing a furnace temperature calculation result when processing 75 sheets.
FIG. 12 is an explanatory diagram of conversion from a furnace temperature to a set temperature using an interference matrix.
[Explanation of symbols]
1 5 zone divided heater 2 outer tube 3 inner tube 4 wafer 5 boat 6 heat insulating plate 7 cascade control TC
8 Profile TC
9 Nozzle 10 Exhaust port 11 Side dummy wafer 12 Product wafer 13 Monitor wafer

Claims (1)

A method for manufacturing a semiconductor device, comprising: a step of supporting n substrates on a boat in a reaction furnace having a heater divided into a plurality of zones, and heating and batch-treating the substrates in a state of being packed on an upstream side of a gas flow. ,
The furnace temperature at an arbitrary position x in the gas flow direction in the furnace is set to y, batch processing is performed a plurality of times while changing the number n of processed sheets, and lnx in each batch processing when the film thickness uniformity becomes equal to or less than a reference value. Determining the relationship between and 1 / y;
A step of approximating the relationship between lnx and 1 / y with a straight line to obtain a _first approximate expression (lnx = a ₁ × 1 / y + b ₁ );
Obtaining a relationship between the slope a ₁ of the first approximate expression and the number n of processed sheets, and a relationship between the intercept b ₁ of the first approximate expression and the number n of processed sheets;
Said first approximate equation relationship between the gradient a ₁ and the processing number n, and a first approximation equation relationship between the intercept b ₁ and the processing number n of approximated by a straight line, the second approximation formula (a ₁ = a _a1 × n + b _a1 ) and a third approximate expression (b ₁ = a _b1 × n + b _b1 );
The relationship between the arbitrary position x in the furnace and the furnace temperature y when the number of processed pieces is n is obtained by the first to third approximate expressions, and the furnace temperature gradient when the number of processed pieces is n is obtained. Process and
Calculating a set temperature of each heater zone so as to form the furnace temperature gradient,
Setting the temperature of each heater zone to the calculated set temperature and batch processing n substrates in the reaction furnace.

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