JP2002252220A - Heat treatment system and heat treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly perform heat treatment without the heat treatment affected by change with time and change in outside environment. SOLUTION: Each of heaters is independently powered, and the temperature of objects to be treated in a zone defined by each heater is controlled so as to correspond to a set point previously programmed, for film forming to be performed. When the film forming is finished, the set point for each zone is updated according to an equation 1: a new set point for each zone = the former set point for the same zone - [a thickness of a film formed in the same zone -an average thickness of films formed in the all zones] × the difference between the latest set point and the former set point/the difference between the thickness of film in the latest film forming and the thickness of film in the former film forming].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a batch-type heat treatment system and a heat treatment method for heat-treating a large number of objects to be processed such as semiconductor wafers at once, and more particularly to measuring the temperature of a semiconductor wafer contained therein. The present invention relates to an adaptive control type batch-type heat treatment system that performs optimal control based on measurement results and a control method thereof.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor device, a batch-type heat treatment system is used in which heat treatments such as a film formation process, an oxidation process or a diffusion process of a large number of objects to be processed, for example, a semiconductor wafer, are collectively performed. I have.

[0003] This heat treatment system can efficiently heat-treat a semiconductor wafer by repeatedly performing a heat treatment operation. In addition, the heat treatment may be different from the initial plan due to a change in external factors. For example, in the case of a film formation process on a semiconductor wafer, it is possible to form a film with an appropriate film thickness on the surface of the semiconductor wafer at first, but the film formation process is repeated on the surface of the semiconductor wafer. The film thickness to be formed may change.

As a technique for solving this kind of problem, for example, Japanese Patent No. 2803460 discloses a technique using a correlation database based on data of a film thickness distribution in a heat treatment furnace in a previous film forming process and a heater temperature. A method of calculating an optimum value of a heater temperature in the film forming process and controlling the heater is disclosed. Here, the correlation database means that a thin film is grown on the surface of the semiconductor wafer by changing the temperature of the heater variously from the reference temperature, and the distribution of the growth film thickness variation at each position in the heat treatment furnace at that time and the heater temperature. 4 is a database storing data (storage data) indicating a correlation with a distribution of a variation amount from a reference temperature.

[0005]

However, according to the technology disclosed in this patent publication, the heater temperature of the next film forming process is determined from the result (film thickness distribution) of the previous film forming process according to the data stored in the correlation database. Is fixedly determined, and even if the heater temperature is changed to the determined temperature, the result of actually forming a film often does not reach a desired value (film thickness). This is because the data stored in the correlation database does not correspond to changes over time in the heat treatment furnace or changes in the external environment.

Further, according to the technique disclosed in this patent publication, the average value of the grown film thickness on the surface of a plurality of semiconductor wafers in the heat treatment furnace can be approximated to a target value to some extent by using a correlation database. The individual film thicknesses cannot be close to their respective target values.

Further, in order to appropriately perform the heat treatment, the operator of the heat treatment system can refer to the film thickness data measured on the heat treatment system and examine changes in the heat treatment conditions such as the temperature of the heater. Is preferred. To this end, for example, heat treatment conditions such as film thickness data and heater temperature are set so that the film thickness data to be referred to (average film thickness, film thickness uniformity, etc.) can be displayed on a screen on the heat treatment system. It is preferred to manage within the heat treatment system.

The present invention has been made in view of the above circumstances, and has as its object to provide a heat treatment system and a heat treatment method capable of appropriately performing a heat treatment while suppressing a change over time and a change in an external environment. . Another object of the present invention is to provide a heat treatment system and a heat treatment method that can manage the results of heat treatment and heat treatment conditions.

[0009]

In order to achieve the above object, a heat treatment method according to a first aspect of the present invention controls the temperature of an object to be processed so that it coincides with a set point, and sets the temperature of an n-th object (where n is (Numerical number) heat treatment is performed, a set point in the (n + 1) th heat treatment is determined by arithmetic processing based on the result of the n-th heat treatment, and the set point is updated to a newly determined new set point. hand,
The (n + 1) th heat treatment is performed.

According to this configuration, the heat treatment temperature can be optimized by updating the set point with reference to the result of the previous heat treatment. Therefore, an appropriate heat treatment result is obtained. For example, in the case where the heat treatment is a film formation process and the formed film thickness is smaller than expected, the heat treatment temperature can be optimized as appropriate, for example, by increasing the temperature of the heat treatment. Further, by updating the set points by the arithmetic processing, it is not necessary to arrange a special device such as a database in the heat treatment device. Furthermore, the update time of the set point is negligibly short compared to the operation time of the heat treatment apparatus, and the update time of the set point has almost no adverse effect on the throughput.

In updating the set point, for example,
The result of the m-th heat treatment (m is a natural number of 2 or more) and the m-th heat treatment
The difference Δd from the result of the first heat treatment, the difference Δt between the set point during the m-th heat treatment and the set point during the (m−1) -th heat treatment, and the result of the m-th heat treatment. Based on this, the set point in the (m + 1) th heat treatment is determined, and the set point is updated to the newly determined new set point.

The update of the set point may be performed based on equations (1) to (4).

The heat treatment is, for example, a film forming process.
In this case, in the update of the set point, the difference between the film thickness formed by the m-th (m is a natural number of 2 or more) film-forming process and the film thickness formed by the (m-1) -th film-forming process is determined. And the difference between the set point during the m-th film forming process and the set point during the (m-1) -th film forming process,
A set point in the (+1) th film forming process is determined.

The heat treatment is, for example, an impurity diffusion treatment. In this case, in the updating of the set point, the concentration of the impurity diffused by the m-th (m is a natural number of 2 or more) impurity diffusion process and the concentration of the impurity diffused by the (m-1) -th impurity diffusion process are determined. And the difference between the set point during the m-th impurity diffusion process and the set point during the (m-1) -th impurity diffusion process,
A set point in the first impurity diffusion process is determined.

The heat treatment is, for example, an etching process. In this case, in updating the set point, the m-th
(M is a natural number of 2 or more) Difference between the etching rate of the first etching processing and the etching rate of the (m-1) th etching processing, the set point at the mth etching processing, and the (m-1) th etching processing The set point in the (m + 1) th impurity diffusion process is determined based on the difference from the set point at the time.

The result of the heat treatment may be stored in association with a set point in the heat treatment. In this case, for example, the result of the heat treatment can be displayed in association with the set point in the heat treatment. Therefore, the change of the set point can be examined with reference to the result of the heat treatment on the heat treatment system. Also,
Within the heat treatment system, the results and set points of the heat treatment can be tracked.

In order to achieve the above object, a second aspect of the present invention is provided.
The heat treatment system according to the aspect of the present invention includes a plurality of heaters,
A heating furnace for accommodating the object to be processed therein, storage means for storing a set point of the temperature of the object at the time of heat treatment, and controlling the heater so that the temperatures of the plurality of objects coincide with the set points. The difference between the result of the m-th heat treatment and the result of the (m-1) -th heat treatment, and the set point of the m-th heat treatment and the m-th heat treatment.
-1 Based on the difference from the set point at the time of heat treatment,
Set point setting means for determining a set point in the (m + 1) th heat treatment and setting the set point in the storage means.

Here, for example, the set point setting means calculates the set point off-line and sets the calculated set point in the storage means.

Further, the result of the m-th heat treatment is referred to as the m-th heat treatment.
There may be provided a heat treatment result storage means for storing the set point in the second heat treatment in association with the set point. Further, the result of the m-th heat treatment stored in the heat treatment result storage means,
Display means for displaying the set point in the m-th heat treatment may be provided. In this case, the result of the heat treatment can be displayed in association with the set point in the heat treatment. Therefore, the change of the set point can be examined with reference to the result of the heat treatment on the heat treatment system. In addition, the results and set points of the heat treatment can be managed in the heat treatment system.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the heat treatment system of the present invention is applied to a batch type vertical heat treatment apparatus will be described.

(First Embodiment) As shown in FIG. 1, a vertical heat treatment apparatus according to the present embodiment has a double tube structure comprising an inner tube 2a and an outer tube 2b made of quartz, for example. A reaction tube 2 is provided, and a metal cylindrical manifold 21 is provided below the reaction tube 2. The upper end of the inner pipe 2 a is opened, and is supported by the manifold 21. Outer tube 2b
Is formed on the ceiling, and the lower end is air-tightly joined to the upper end of the manifold 21.

In the reaction tube 2, a large number, for example, 150
A plurality of wafers W (product wafers) serving as workpieces are horizontally arranged in a shelf on a wafer boat 23 as a wafer holder at predetermined intervals vertically. The wafer boat 23 is held on a lid 24 via a heat insulating cylinder (heat insulating body) 25. The lid 24 is configured to be vertically movable by a lift 26. When the lid 24 is lifted by the lift 26, the lower side of the manifold 21 is closed, and the wafer W is loaded into the reaction tube 2.

Around the reaction tube 2 is provided a heater section 3 made of, for example, a resistor. The heater unit 3 includes, for example, heaters 31 to 35 arranged in five stages. The heaters 31 to 35 are connected to the power controllers 36 to 4.
0, power is supplied independently. Heater 3
According to 1 to 35, the inside of the reaction tube 2 is divided into five zones as shown in FIG. The heater unit 3, the reaction tube 2, and the manifold 21 constitute a heating furnace.

The manifold 21 is provided with a plurality of gas supply pipes for supplying gas into the inner pipe 2a. FIG. 1 shows three gas supply pipes 41, 42, and 43 for easy understanding. Each gas supply pipe 4
1, 42, and 43 include flow rate adjustment units 44, 4 such as a mass flow controller (MFC) for adjusting a gas flow rate.
For example, dichlorosilane, ammonia and nitrogen are supplied via 5, 46, respectively. Further manifold 2
An exhaust pipe 27 is connected to 1 so as to exhaust gas in the reaction pipe 2 from a gap between the inner pipe 2a and the outer pipe 2b. The exhaust pipe 27 is connected to a vacuum pump (not shown).
The exhaust pipe 27 has a pressure for adjusting the pressure inside the reaction pipe 2.
A pressure adjusting unit 28 including a combination valve, a butterfly valve, a valve driving unit, and the like is provided.

On the inner surface of the inner tube 2a, five thermocouples (temperature sensors) Sin1 to Sin5 are arranged in a line in the vertical direction. The thermocouples Sin1 to Sin5 are covered with, for example, a quartz pipe or the like in order to prevent metal contamination of the wafer W, and are arranged in five zones shown in FIG.

On the outer surface of the outer tube 2b, a plurality of thermocouples (temperature measuring units) Sout1 to Sout5 are arranged in a line in the vertical direction. Thermocouples Sout1 to Sout5 are also shown in FIG.
Are arranged corresponding to the five zones shown in FIG.

This vertical heat treatment apparatus includes a control unit (controller) 100 for controlling processing parameters such as the temperature, gas flow rate, and pressure of the processing atmosphere in the reaction tube 2. The control unit 100 includes thermocouples Sin1 to Sin5 and Sout1.
ＳSout5 are output, and control signals are output to the power controllers 36 to 40 of the heaters 31 to 35, the pressure adjustment unit 28, and the flow rate adjustment units 44 to 46.

FIG. 2 shows the configuration of the control unit 100. As shown in FIG. 2, the control unit 100 includes a model storage unit 111,
Recipe storage unit 112, ROM 113, RAM 114
, An I / O port 115, a CPU 116, and a bus 117 interconnecting these.

The model storage unit 111 stores thermocouples Sin1 to Si
From the output signals (measurement temperatures) of n5 and Sout1 to Sout5, the temperatures at the center and ends of the wafer W placed on the wafer boat 23 are estimated (calculated), and the estimated temperature is set as a target value. A model (mathematical model; high-order / multidimensional function) designed to indicate the current (power) to be supplied to the heaters 31 to 35 is stored. The model design method will be described later.

The recipe storage unit 112 stores a recipe that determines a control procedure according to the type of film forming process performed by the heat treatment apparatus. Each recipe includes a temperature recipe (a target value of a temperature change to be processed by the wafer W to be processed; a target temperature trajectory). For normal batch processing, 1
For one type of film forming process, one temperature recipe is prepared for all wafers. On the other hand, in the present embodiment, as illustrated in FIG. 3A, the inside of the reaction tube 2 is vertically divided into five zones, and as shown in FIG. A temperature recipe (temperature target trajectory) is prepared for each. The set points (temperature at the time of executing the film forming process) Tset1 to Tset5 of the temperature recipe of each zone are, for example,
Zone 1 is 852 ° C (Tset1), Zone 2 is 850 ° C
(Tset2), zone 3 is 849 ° C (Tset3), zone 4
Is 848 ° C (Tset4), Zone 5 is 846 ° C (Tset5)
Is set to However, set points Tset1 to Tset
set5 is adjusted for each film forming process based on the result of the previous film forming process and the like.

Returning to FIG. 2, the ROM 113 stores the EEPROM
M, a flash memory, a hard disk, and the like, and is a recording medium that stores an operation program of the CPU 116 and the like.

The RAM 114 functions as a work area for the CPU 116 and the like. The I / O port 115 transmits measurement signals of the thermocouples Sin1 to Sin5 and Sout1 to Sout5 to the CPU.
The control signal is supplied to the CPU 116, and the control signal output from the CPU 116 is output to each unit (the power controllers 36 to 40, the flow rate adjusting units 44 to 46, and the pressure adjusting unit 28). Also, I /
An operation panel 118 is connected to the O port 115. The bus 117 transmits information between the units.

The CPU 116 includes a DSP (Digital Signal).
Processor 113).
The operation of the heat treatment apparatus is controlled according to the recipe stored in the recipe storage unit 112 in response to an instruction from the operation panel 118. Specifically, the CPU 116 controls the model storage unit 11
1 is read out, and the recipe stored in the recipe storage unit 112 is read out. Then, the processing operation is performed according to the recipe. In particular, in the present embodiment, CPU 116 includes thermocouples Sin1 to Si
n5 and measured values from Sout1 to Sout5 and instruction values to power controllers 36 to 40 (power controllers 36 to 40).
Values indicating the power supplied to the heaters 31 to 35), and the temperatures T1 to T5 of the wafers W1 to W5 in the zones 1 to 5 are estimated every moment, and the estimated value is set to a preset set point Tset1 for each zone. The power supply is instructed to the power controllers 36 to 40 so as to coincide with Tset5.

The CPU 116 also issues an instruction to the flow rate adjusting units 44 to 46, an instruction to the pressure adjusting unit 28, and the like, similarly to the control of a normal heat treatment apparatus.

Next, a film forming method for forming a nitride film on the wafer W by using the batch type heat treatment apparatus having the above configuration will be described as an example.
The heat treatment method of the present invention will be described with reference to FIGS.

First, the operator inputs the contents of processing (formation of a nitride film) on the operation panel 118. CPU116
Reads a recipe for forming a nitride film from the recipe storage unit 112 in response to the input instruction. The CPU 116
The heater 3 sets the inside of the reaction tube 2 to a load temperature defined in the recipe, for example, about 400 ° C. Also, CP
The U116 reads the set points Tset1 to Tset5 for each zone which are determined in advance (the method of obtaining the set points will be described later) and sets them as set points Tset1 to Tset5 of the temperature recipe for each zone shown in FIG. Step S1).

Next, the CPU 116 sets a predetermined number of wafers W to be processed on the wafer boat 23, for example, 100 wafers.
The wafer boat 23 on which the wafers W are mounted and on which the wafers W are mounted is lifted by the lift 26. And the CPU 116
Makes the flange at the lower end of the manifold 21 and the lid 24 airtight, and loads the wafer W into the reaction tube 2 (step S2).

When the loading of the wafer W is completed, the CPU 116 performs the following according to the recipe read from the ROM 113.
The exhaust system including the pressure adjusting unit 28 is controlled to start the exhaust operation. Further, the CPU 116 starts increasing the temperature by increasing the power supplied to the heater unit 3 (step S3).

For the wafers W in each of the zones 1 to 5, the CPU 116 measures the measured values from the thermocouples Sin1 to Sin5 and Sout1 to Sout5 and the instruction values to the power controllers 36 to 40 (the power controllers 36 to 40 control the heaters 31 to 35 (A value indicating the power supplied to the wafer W)
, And supply power is instructed to the power controllers 36 to 40 to control the temperature such that the estimated value coincides with the predetermined set points Tset1 to Tset5.

Next, the CPU 116 determines whether or not the wafer temperatures T1 to T5 of the zones 1 to 5 have reached the set points Tset1 to Tset5, that is, whether or not the temperature raising process has been completed (step S4). ), If not reached, step S3
The temperature raising process is continued. If the temperature has reached, the temperature raising process is ended, and the process proceeds to a temperature keeping process for maintaining a constant temperature.

During the heat retention process, the CPU 116
The wafer temperatures in zones 1 to 5 are T1, T2, T3, T4, T5
And the set points of the temperature recipe of each zone 1 to 5 are Tset1, Tset2, Tset3, Tset4, Tset5
In such a case, the control is performed such that the difference between the actual temperature and the set point is minimized as a whole. For example, C
The PU 116 uses the least squares method to calculate (T1−Tset1)
² + (T2-Tset2) ² + (T3-Tset3) ² + (T4-
Tset4) ² + (T5−Tset5) so that ² becomes minimum.
The power supplied to the heaters 31 to 35 is individually controlled.

In the heat retaining process, the wafer temperature T1 to T5 of each of the zones 1 to 5 is set at the set point Tse of each of the zones 1 to 5.
When the temperature is stabilized at t1 to Tset5, the CPU 116 supplies a processing gas into the reaction tube 2 and executes a film forming process (Step S).
5).

Next, the CPU 116 determines whether or not the film forming process has been completed (step S6), and if not, returns to step S5 to continue the temperature control and the film forming process (step S5). ) When the film forming process is completed, the supply of the film forming gas is stopped, the inside of the reaction tube 2 is cooled, and then the wafer boat 23 is unloaded (step S7).

From the plurality of wafers W placed on the unloaded wafer boat 23, at least one wafer W (monitor wafer) is taken out for each of zones 1 to 5, and the film thickness of each monitor wafer is measured. Then, based on the actually measured film thickness of the monitor wafer, each zone 1 in the next film forming process is
~ 5 set points are determined. The operator stores the determined set point in the RAM 114 as a set point for the next film forming process from the operation panel 118, and updates the set point (step S8).

The set point updating process in step S8 will be described in more detail with reference to FIG.

First, the actual film thicknesses D1 to D5 of the nitride film formed by the current film formation process are measured for five monitor wafers W selected one by one from the five zones 1 to 5 (step). S11).

Next, the average value Dav of the measured film thicknesses D1 to D5
e (= (D1 + D2 + D3 + D4 + D5) / 5) is calculated (step S12). Subsequently, the zone 1-5 with separately from the film and the current forming the last difference in thickness of the thus formed on the monitor wafer film _{ΔD1~ΔD5 (ΔD1 = D1 n -D1 n} -1 ~ΔD5 = D
5 _n -D5 _{n -1)} to calculate the (step S13). Note that n
Is the current (n-th) deposition process, and n-1 is the previous (n-1)
This shows the second film forming process.

[0048] In addition, the zone 1 to 5 apart from the difference between the previous and the current set point _{Δt1~Δt5 (Δt1 = t1 n -t1 n} -1
_{~Δt5 = t5 n -t5 n-1} ) to calculate the (step S1
4). Next, a new set point for each of the zones 1 to 5 is obtained according to Equation 5 (step S15).

[0049]

## EQU5 ## New set point Tseti of ith zone = previous setpoint Tseti of ith zone− (actual measured value Di of film thickness on monitor wafers in ith zone−average value Dave of film thickness on all monitor wafers ) × (set point difference Δti of ith zone / actual thickness difference ΔDi of ith zone)

The operator operates the operation panel 118, for example.
Then, the obtained value is registered in the RAM 114 as a new set point. The set points for each of the zones 1 to 5 registered in the RAM 114 will be set points of the temperature recipe for each of the zones 1 to 5 in the next film forming process.

It should be noted that instead of “the average value Dave of the film thickness on all monitor wafers”, “the target value Dtarget1 of the film thickness in that zone”
By using “5Dtarget5”, the film thickness can be made to coincide with the target film thickness.

As described above, according to the present embodiment, the temperature of the wafer W placed on the wafer boat 23 is monitored in a non-contact manner for each of the zones 1 to 5, and the temperature of the wafer W is set to the set point. The heater unit 3 is adaptively controlled so as to be maintained. In addition, the set point of the temperature recipe (temperature of the wafer at the time of film formation) is readjusted for each of the zones 1 to 5 by arithmetic processing using the result (film thickness) of the previous film formation processing. Changes and film formation environment (external temperature, atmospheric pressure)
Even if a change occurs, film formation with an appropriate film thickness becomes possible.

Next, a method of designing a model and a recipe will be described. The models are thermocouples Sin1 to Sin5 and Sou
From the outputs (measured values) of t1 to Sout5 and the power supplied to the heaters 31 to 35, the temperature of the wafer W is estimated, and
Any model (multivariable, multidimensional, multioutput function) can be used as long as it is a mathematical model that can specify the power supplied to the heaters 31 to 35 in order to set the set of estimated temperatures to the target temperature. .

As such a model, for example, the model disclosed in US Pat. No. 5,517,594 can be used. In the following, U.S. Pat.
The model disclosed in Japanese Patent No. 594 will be described as an example.

First, five test wafers having thermocouples Swc and Swe incorporated at the center and the periphery are prepared. Next, the test wafer and the normal wafer are placed on the wafer boat 23 such that these five test wafers are located one by one in the five zones 1 to 5 in FIG. . Next, the wafer boat 23 is loaded into the reaction tube 2. Next, a high-frequency band signal and a low-frequency band signal are applied to the heaters 31 to 35 and the thermocouples Sin1 to Sin5 and Sout1 to Sout
out5 output, output of thermocouples Swc and Swe on test wafer (center temperature and peripheral temperature of wafer), heaters 31 to 3
Data such as the current supplied to 5 is acquired at a sampling period of, for example, 1 to 5 seconds.

Next, a certain temperature range, for example, 400 ° C.
The temperature zone is set at an interval of 100 ° C. within a range of １1100 ° C. The reason why the temperature bands are set at intervals of 100 ° C. is that if one tries to cover a wide temperature band with one model, the estimation of the temperature or the like becomes inaccurate. From the acquired data, ARX shown in Expression 6 for each temperature band
(Automatic regression) Set the model.

[0057]

[6] _{y t + AA 1 y t-} 1 + AA 2 y t-2 + ... + AA n y
_{tn = BB 1 u t-1} + BB 2 u t-2 + ... + BB n u tn + e
_t y _t: p 1 vector content of which the following content at the time t and the components: the amount of variation from the equilibrium temperature y _bias the output of the thermocouple Sin1~Sin5 (5 component in this example), thermocouple Sout1 ~ Sout5
Of the output of the thermocouple Sw from the equilibrium temperature y _bias (five components in this example), and the amount of fluctuation of the output of the thermocouple Sw set on the wafer from the equilibrium temperature y _bias (five in this example). Therefore, in this example, y _t is a vector of 15 rows and 1 column. u _t : a vector of m rows and 1 column having a variation amount from the heater power equilibrium value u _bias at the time point t (in this example, 5 zones and 1 column because the heater has 5 zones). _et : a vector of m rows and 1 column having white noise as a component. n: delay (for example, 8). AA _{1 to} AA _n : a matrix of p rows and p columns (15 rows and 15 columns in this example). BB _{1 to} BB _n : matrix of p rows and m columns (15 rows and 5 columns in this example).

[0058] Here, each coefficient _AA 1 _{~AA n} and _BB 1 ~
BB _n is determined using the least squares method or the like.

When the obtained ARX model is expressed by a space state equation, it is expressed by the following equation (7).

(Equation 7)

From here, the thermocouples (Sin1 to Sin5, Sout1
~Sout5), the temperature T _thermo, obtains a model to estimate the wafer temperature from the heater power _{u t.} The portion S _t (P ₁ row 1 column) where the output y _{t of} Expression 6 can be measured and the wafer temperature W _t (P ₂
Row 1 column). Accordingly, C is divided into C _S and C _W , and y _bias is divided into S _bias and W _bias . The wafer temperature model is calculated by Expression 8.

[0061]

Equation 8] _{X t + 1 = AX t +} BU t + k f e t S t = C s X t + [I p, 0] e t on solving suitable Riccati equation with respect to formula, feedback gain L Is obtained, the wafer temperature model becomes as shown in Expression 9.

[0062]

Equation 9] _{X t + 1 = AX t +} B (U t + U bias) + L (T thermo -C S X
_t + S _{bias) T model,} at _{t = C w X t + W} bias _{here, T model, t} is the predicted wafer temperature.

Next, the wafer temperature is measured again using the test wafer. The model is tuned by comparing the wafer temperature T _model estimated based on Expression 9 with the actually measured value T _water . This tuning operation is repeated a plurality of times as necessary.

In order to improve the processing speed of the actual film forming system,
The order of the created model is reduced to about 10th order, and the model is mounted on the heat treatment apparatus.

On the other hand, the operation program of the CPU 116 is set so as to minimize the time average of the fluctuation of the wafer temperature estimated from the temperature setting value.

Further, according to the type of the film forming process, the target temperature trajectory Ttr which enables uniform film formation in each zone.
aj (t), that is, a temperature recipe is designed. Subsequently, control is performed so that all five zones follow the target temperature trajectory, and a film formation process is executed on a test basis. After the processing, the thickness of the formed film is measured, and a variation in the film thickness is checked.

For example, when the film thickness of the upper wafer is smaller than the film thickness of the lower wafer, even if the direct cause is unknown, it is necessary to make the film thickness substantially equal by relatively increasing the temperature of the upper wafer. Can be. Therefore, the target temperature trajectory Ttraj (t) is corrected by using the least squares method or the like so as to minimize the variation. This is the temperature recipe for each zone as shown in FIG. It is also possible to further tune this temperature recipe.

In this way, a model for defining an output for estimating the wafer temperature and setting the wafer temperature to the target temperature and a recipe are set according to the number of processed wafers and the arrangement thereof. Is stored in the recipe storage unit 112.

Thereafter, at the time of actual film formation, these models and recipes are appropriately selected, read out, and used for control. However, the set points of the recipe are sequentially updated for each film forming process.

(Second Embodiment) The second embodiment differs from the first embodiment in that the control unit 100 of the first embodiment is provided with a data storage unit 119. I have. Hereinafter, the points different from the first embodiment will be mainly described.

FIG. 6 shows the configuration of the control unit 100 according to the present embodiment. As shown in FIG. 6, the control unit 100 includes a model storage unit 111, a recipe storage unit 112, a ROM 113
, RAM 114, I / O port 115, CPU 1
16 and a data storage unit 119, which are mutually connected to a bus 117.

The data storage unit 119 stores the results of the film forming process performed by the heat treatment apparatus, that is, the measured values (film thickness data) of the film thickness formed on the wafer W, in the heat treatment conditions (for example,
Log indicating the number of heat treatments, set points, and temperature changes).

The CPU 116 controls the operation of the heat treatment apparatus in the same manner as in the first embodiment. In addition, the operator of the heat treatment system refers to the film thickness data measured on the heat treatment system to change the set point. The film thickness data and the set points are stored in the data storage unit 119 so that the data can be examined. Further, the CPU 116 reads out the film thickness data and set points stored in the data storage unit 119, and reads the read-out film thickness data and set points, for example, as shown in FIG.
8 is displayed on the screen. On this screen, the number of heat treatments (film formation processing), set points for each of zones 1 to 5, and film thickness data are displayed. The “Graph” key in FIG. 7 has a function of displaying the currently displayed film thickness data in a graph. Therefore, when the key of the “graph” is selected, the film thickness data can be easily viewed.

Next, the heat treatment method of the present invention will be described with reference to FIG. 8 by taking as an example a film formation method for forming a nitride film on a wafer W using the batch-type heat treatment apparatus having the above configuration. FIG. 8 is a diagram for explaining a procedure for storing film thickness data.

First, the operator inputs the contents of the n-th heat treatment (formation of the nitride film) on the operation panel 118.
In response to the input instruction, the CPU 116 sets the set points Tset1 to Tset5, loads the wafer W, raises the temperature of the reaction tube 2 and controls the temperature in the same manner as in the first embodiment. (Step S2)
1).

When the n-th film forming process is completed, the CPU
116 indicates a heat treatment condition (for example,
The number of heat treatments and set points are stored (Step S)
22). Then, by a wafer transfer mechanism (not shown), at least one of
One wafer W (monitor wafer) is transferred to the measuring device (step S23).

When the monitor wafer is transferred to the measuring device,
The thickness of the film formed on the monitor wafer is measured by the measuring device (Step S24). Then, the measurement result (film thickness data) is sent to the heat treatment apparatus by the operator inputting it from the operation panel 118 or storing it in the data storage unit 119 of the heat treatment apparatus via a flexible disk or a remote terminal. (Step S25). CP
U116 associates the sent measurement results with the heat treatment conditions (the number of heat treatments, set points), and
19 (step S26).

As described above, since the film thickness data is stored in the data storage unit 119 in association with the heat treatment conditions, the operator of the heat treatment system operates the operation panel 118 to operate the operation panel 118 as shown in FIG. Film thickness data, set points, and the like can be displayed on the screen of the panel 118. Therefore, the operator can consider changing the set point with reference to the film thickness data measured on the heat treatment system. Further, the history of heat treatment conditions such as film thickness data and set points can be managed in the heat treatment system.

Further, as in the first embodiment, the set points of the zones 1 to 5 at the time of the (n + 1) th heat treatment are determined based on the measured film thickness of the monitor wafer.
The operator sets the determined set point as the (n + 1) -th set point from the operation panel 118 to the RA.
The set point is stored in M114 and the set point is updated.

As described above, according to the present embodiment, the film thickness data is stored in the data storage unit 119 in association with the heat treatment conditions. Therefore, when the operator of the heat treatment system operates the operation panel 118,
Film thickness data, set points, and the like can be displayed on the screen of the operation panel 118. Therefore, the operator of the heat treatment system can consider changing the set point with reference to the film thickness data measured on the heat treatment system. Further, the history of heat treatment conditions such as film thickness data and set points can be managed in the heat treatment system.

The batch type heat treatment apparatus and its adaptive control method according to the embodiment of the present invention and the method of designing models and recipes used for control have been described above. However, the present invention is limited to the above embodiment. However, various modifications and applications are possible.

For example, in the above-described embodiment, the present invention has been described by taking the thermal CVD apparatus for forming a nitride film as an example, but the type of processing is arbitrary, and the CVD apparatus for forming other types of films can be used.
The present invention is applicable to various batch-type heat treatment apparatuses such as an oxidation apparatus and an etching apparatus. A model and a recipe are designed for each type.

In the above embodiment, a plurality of temperature sensors Sin1 to Sin5 and Sout1 to
From the output of Sout5 and the power of the heaters 31 to 35, the temperature of the center portion and the peripheral portion of the wafer in each zone was obtained indirectly in a non-contact manner by a mathematical model. However, instead of this method, the same control can be performed by directly measuring the temperature of the wafer using a radiation thermometer and supplying the measured value to the CPU 116.

It is also possible to arrange a thermocouple (temperature sensor) on the dummy wafer, arrange this wafer on the wafer boat 23, and directly measure the temperature of the wafer from the output of the thermocouple.

However, in the method using a radiation thermometer, the temperature of the wafer cannot be measured in the case of the type of film to be formed, for example, a light-impermeable film. Further, even when the wafers are stacked on the wafer boat 23, the temperature of the wafers cannot be measured. Further, in the method using a dummy wafer provided with a temperature sensor, the high temperature in the reaction tube 2 may evaporate the metal from the sensor or the wire mounted on the dummy wafer and contaminate the wafer with the metal. According to the method using the above-described model, by disposing the sensor outside the inner tube 2a, it is possible to relatively accurately measure (estimate) the temperature of the wafer in each zone while suppressing metal contamination in the reaction tube. it can.

The method of updating the set point is as follows.
The method is not limited to the method shown in Expression 5, and can be appropriately changed.
For example, the correction may be made as shown in Expression 10.

## EQU10 ## New set point Tseti of ith zone = i-th zone
The previous set point of the zone Tseti−α (actual measured value Di of the film thickness on the monitor wafer in the i-th zone−the average value Dave of the film thickness on all monitor wafers) × β (set point difference Δti / i-zone thickness difference ΔDi) α and β are arbitrary coefficients

In Equation 10, a target value may be used instead of the average value Dave of the film thickness on all monitor wafers.

The number of heater stages (the number of zones), the number of monitor wafers extracted from each zone, and the like can be arbitrarily set. Further, in the above-described embodiment, an example in which the film thickness of the film formed by the film forming process is adjusted has been described. For example, the present invention is applicable to any type of heat treatment in which the result of the heat treatment depends on the temperature during the heat treatment. The invention is applicable. For example, it is effective for optimizing the results of various heat treatments such as the diffusion concentration or diffusion depth, the etching rate, the reflectance, the embedding characteristics, and the step coverage in the impurity diffusion processing.

The arithmetic expressions of the new set points shown in Expressions 5 and 10 can be appropriately changed according to the type of heat treatment. For example, in the case of a CVD process, Gas Depl.
Since an etion effect exists, it is preferable to modify and use Equations 5 and 10 so as to compensate for this effect.

The present invention is not limited to the heat treatment of a semiconductor wafer, but is also applicable to, for example, heat treatment of a semiconductor substrate or a PDP substrate.

[0091]

As described above, according to the present invention,
In a batch-type heat treatment apparatus, heat treatment can be appropriately performed while suppressing changes over time and the influence of the external environment.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a heat treatment apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration example of a control unit in FIG. 1;

3A is a diagram showing a zone in a reaction tube, and FIG. 3B is a diagram showing an example of a target temperature trajectory for each zone.

FIG. 4 is a flowchart illustrating a process for one film forming process.

FIG. 5 is a flowchart illustrating a set point update process.

FIG. 6 is a block diagram illustrating a configuration example of a control unit according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a display example of stored film thickness data and set points.

FIG. 8 is a diagram for explaining a procedure for storing film thickness data.

[Explanation of symbols]

 2 Reaction Tube 3 Heater 21 Manifold 23 Wafer Boat 24 Lid 25 Heat Insulation Cylinder (Insulating Body) 31 Upper Heater 32 Upper Middle Heater 33 Middle Heater 34 Lower Middle Heater 35 Lower Heater 36-40 Power Controller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Park Eietsu 5-36 Akasaka, Minato-ku, Tokyo TBS Transmission Center Tokyo Electron Limited (72) Inventor Fujio Suzuki 5-3-1 Akasaka, Minato-ku, Tokyo No. 6 TBS Release Center Tokyo Electron Co., Ltd. (72) Inventor Yuichi Takenaga 5-3-6 Akasaka, Minato-ku, Tokyo TBS Release Center Tokyo Electron Co., Ltd. (72) Inventor Asami Ohara Tokyo Metropolitan Port Tokyo Electron Co., Ltd. (72) Inventor Naohide Ito 5-3-6 Akasaka-ku Tokyo Electron Co., Ltd. F-Term (reference) 4G075 Tokyo Electron Co., Ltd. AA30 AA63 BC04 BC06 BD14 CA02 CA13 CA65 DA02 DA04 EA01 EA06 EB01 ED13 FB06 FC06 4K056 AA09 BB06 CA18 FA04 4K061 AA01 BA11 DA05 GA02 5F045 BB03 DP19 EK06 EK22 GB16 GB17 5H323 AA05 CA06 CB02 CB42 CB44 DA04 DA05 DB15 GG02 JJ06 LL21 NN03

Claims (13)

[Claims] 1. An n-th (n is a natural number) heat treatment is performed by controlling the temperature of an object to be set to coincide with a set point, and an arithmetic process is performed based on a result of the n-th heat treatment.
A heat treatment method comprising: determining a set point in the (n + 1) th heat treatment, updating the set point to a newly determined new set point, and executing the (n + 1) th heat treatment. 2. The method according to claim 1, wherein the updating of the set point is performed at the m-th (m
Is a natural number equal to or greater than 2) the difference Δd between the result of the first heat treatment and the result of the (m−1) th heat treatment, and the set point of the m-th heat treatment and the set point of the (m−1) th heat treatment. Based on the difference Δt and the result of the m-th heat treatment,
The heat treatment method according to claim 1, wherein a set point in the (m + 1) th heat treatment is determined, and the set point is updated to a newly determined new set point. 3. The heat treatment method according to claim 1, wherein in the updating of the set point, a new set point is determined based on Equation 1. [Equation 1] New set point = Previous set point-
[Result of actual heat treatment-Result of average heat treatment] × Set point difference Δt / Difference of heat treatment result Δd 4. The heat treatment method according to claim 1, wherein in the updating of the set point, a new set point is determined based on Equation 2. [Equation 2] new set point = previous set point−
[Result of actual heat treatment−Target value of result of heat treatment] × Set point difference Δt / Difference of heat treatment result Δd 5. The method according to claim 1, wherein the set point is set for each of a plurality of zones defined by a plurality of heaters. In the updating of the set point, a new set point of each zone is determined based on Equation (3). 3. The heat treatment method according to claim 1, wherein the heaters are individually controlled such that the temperature of the object to be processed matches the set point for each zone. ## EQU3 ## New set point = previous set point of same zone− [result of actual heat treatment of same zone−result of heat treatment of all zones] × difference of set point of same zone / difference of heat treatment result of same zone 6. The set point is set for each of a plurality of zones defined by a plurality of heaters. In the updating of the set point, a new set point of each zone is determined based on Equation 4; 3. The heat treatment method according to claim 1, wherein the heaters are individually controlled such that the temperature of the object to be processed matches the set point for each zone. ## EQU4 ## New set point = previous set point of same zone− [result of actual heat treatment of same zone−target value of heat treatment result] × difference of set point of same zone /
Difference in heat treatment results in the same zone 7. The heat treatment is a film forming process for controlling a heater so that the temperatures of a plurality of objects to be processed coincide with a set point and supplying a processing gas into a heating furnace. , The film thickness formed by the m-th (m is a natural number of 2 or more) film forming process and the (m−1) th film thickness
Based on the difference between the film thickness formed by the first film forming process and the difference between the set point during the m-th film forming process and the set point during the (m−1) -th film forming process, the (m + 1) -th film forming process is performed. 7. The heat treatment method according to claim 1, wherein a set point in the film forming process is determined. 8. The heat treatment is an impurity diffusion process in which a heater is controlled so that the temperatures of a plurality of objects to be processed coincide with a set point and a processing gas is supplied into a heating furnace. , The difference between the impurity concentration diffused by the m-th (m is a natural number of 2 or more) impurity diffusion process and the impurity concentration diffused by the (m-1) -th impurity diffusion process, and the m-th impurity diffusion 7. A set point in the (m + 1) th impurity diffusion process is determined based on a difference between a set point in the process and a set point in the (m-1) th impurity diffusion process. The heat treatment method according to any one of the above items. 9. The heat treatment is an etching process for controlling a heater so that the temperatures of the plurality of workpieces coincide with a set point and supplying an etching gas into a heating furnace. , The etching rate of the m-th (m is a natural number of 2 or more) etching process and the m-th etching process
-The difference between the etching rate of the first etching process, the set point at the m-th etching process, and the
The heat treatment method according to any one of claims 1 to 6, wherein a set point in the (m + 1) th impurity diffusion process is determined based on a difference from a set point in one etching process. . 10. The heat treatment method according to claim 1, wherein a result of the heat treatment is stored in association with a set point in the heat treatment. 11. A heating furnace having a plurality of heaters and accommodating a plurality of objects to be processed therein, storage means for storing a set point of the temperature of the objects during heat treatment, Heat treatment means for controlling the heater so that the temperature coincides with the set point; and the result of the m-th heat treatment (m is a natural number of 2 or more) and the m-th heat treatment.
A set point in the (m + 1) th heat treatment is determined based on a difference between the result of the −1 heat treatment and a difference between a set point of the mth heat treatment and a set point of the (m−1) th heat treatment. And a set point setting means for setting the set point in the storage means. 12. A heat treatment result storage means for storing a result of the m-th heat treatment in association with a set point in the m-th heat treatment.
2. The heat treatment system according to 1. 13. The apparatus according to claim 12, further comprising display means for displaying a result of the m-th heat treatment stored in the heat treatment result storage means and a set point in the m-th heat treatment. Heat treatment system.