JP2001345275A - Heat treatment device, method for controlling heat treatment device, and method for determining place to be measured in circumference of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out heat treatment a semiconductor wafer by considering temperature distribution on the semiconductor wafer. SOLUTION: In this heat treatment device, a substrate is arranged in a treatment chamber for heat treatment. The heat treatment device is equipped with a heating part, a temperature measurement part that measures temperature at a center measurement place that is positioned near the center of the substrate, and a plurality of circumference measurement places that are positioned near the circumference of the substrate, a typical temperature calculation part that calculates the typical temperature of the substrate, based on temperature at the center measurement place and the plurality of circumference measurement places, and a control part that controls the heating part, based on the typical temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus for heat-treating a substrate such as a semiconductor wafer, a method of controlling the heat treatment apparatus, and a method of determining a peripheral measuring point of a substrate. The present invention relates to a heat treatment apparatus, a method for controlling the heat treatment apparatus, and a method for determining a peripheral measurement point of a substrate.

[0002]

2. Description of the Related Art Generally, a horizontal heat treatment apparatus or a vertical heat treatment apparatus is known as a heat treatment apparatus for performing heat treatment such as film formation processing, oxidation treatment or diffusion treatment on a large number of semiconductor wafers at once. Vertical heat treatment apparatuses are becoming mainstream because of little air entrapment.

The vertical heat treatment apparatus includes a vertical reaction tube provided on a cylindrical manifold, and a heater provided to surround the reaction tube. Then, a large number of wafers are held in a shelf shape by a holder called a wafer boat and carried into the reaction tube from the opening at the lower end of the manifold to perform heat treatment.

[0004] During this heat treatment, the heat treatment apparatus is controlled based on the heated temperature of the semiconductor wafer.

[0005]

However, when the heat treatment is performed by the heat treatment apparatus, the temperature of the semiconductor wafer is not uniform and usually has a temperature distribution. For this reason, there is a problem as to which temperature on the semiconductor wafer is to be used to control the heat treatment apparatus.

When the width of the temperature distribution is large, slip lines are likely to be generated on the semiconductor wafer. The slip line is one type of step formed on the semiconductor wafer and causes a reduction in the yield of semiconductor devices.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a heat treatment apparatus and a control of the heat treatment apparatus which enable a heat treatment of a substrate in consideration of a temperature distribution of the substrate such as a semiconductor wafer. It is an object of the present invention to provide a method and a method for determining a peripheral measuring point for measuring a temperature on a substrate.

[0008]

Means for Solving the Problems (1) In order to achieve the above object, a heat treatment apparatus according to the present invention is a heat treatment apparatus for arranging a substrate in a processing chamber and performing heat treatment. A heating unit for heating from the periphery of the substrate, a temperature measurement unit for measuring the temperature of a central measurement point located near the center of the substrate and a plurality of peripheral measurement points located near the periphery of the substrate, and the temperature measurement unit Based on the temperature of the central measurement point and the plurality of peripheral measurement points measured by the representative temperature calculation unit that calculates the representative temperature of the substrate, based on the representative temperature calculated by the representative temperature calculation unit, A control unit for controlling the heating unit.

Since the representative temperature of the substrate is calculated based on the temperatures of the central measurement point and the plurality of peripheral measurement points, the representative temperature is accurately calculated by reflecting the temperature distribution on the substrate, and the heating unit based on the representative temperature is calculated. Precise control becomes possible.

The representative temperature can be calculated, for example, by weighting and averaging the average value of the temperatures at a plurality of peripheral measuring points and the temperature at the central measuring point.

(2) The heat treatment apparatus according to the present invention comprises:
A heat treatment apparatus for performing heat treatment by arranging a substrate in a processing chamber, comprising: a heating unit for heating the substrate from a periphery of the substrate; a central measurement point located near a center of the substrate; and a periphery of the periphery of the substrate. A temperature measurement unit that measures the temperature of a plurality of peripheral measurement points located in a temperature difference calculation unit that calculates a temperature difference in the substrate based on the temperature of the central measurement point and the temperature of the plurality of peripheral measurement points. A control unit that controls the heating unit based on the temperature difference calculated by the temperature difference calculation unit.

Since the temperature difference in the substrate is calculated based on the temperature of the central measurement point and the temperatures of the plurality of peripheral measurement points, the temperature difference accurately reflecting the temperature distribution in the substrate and the heating based on the temperature difference are calculated. The precise control of the section can be performed.

As a result, the temperature difference in the substrate can be suppressed within an appropriate allowable range, and, for example, slip lines generated on the semiconductor wafer can be reduced.

The temperature difference can be calculated, for example, by selecting the difference having the largest absolute value from the temperature difference between the center measurement point and the plurality of peripheral measurement points.

(3) A method for controlling a heat treatment apparatus according to the present invention is a method for controlling a heat treatment apparatus for performing a heat treatment on a substrate, comprising: a central measurement point located near the center of the substrate; A temperature measuring step of measuring the temperature of a plurality of peripheral measuring points located in the vicinity, and calculating a representative temperature of the substrate and a temperature difference in the substrate based on the temperature of the central measuring point and the temperatures of the plural peripheral measuring points. A representative temperature / temperature difference calculating step, and a control step of controlling the heat treatment apparatus based on the representative temperature and the temperature difference calculated in the representative temperature / temperature difference calculating step.

The heat treatment apparatus can be accurately controlled in consideration of the temperature distribution of the substrate, based on the representative temperature of the substrate and the temperature difference within the substrate calculated from the temperature at the central measurement point and the temperatures at the plurality of peripheral measurement points.

Here, the control step includes a control parameter deriving step of deriving a control parameter of the heat treatment apparatus based on the representative temperature, and correcting the control parameter derived in the control parameter deriving step based on the temperature difference. And a control parameter correcting step.

(4) A method for determining a peripheral edge measuring point of a substrate according to the present invention comprises a plurality of peripheral edge measuring points located near the peripheral edge of the substrate and for measuring a temperature at the time of heat treatment of the substrate. A heating step of arranging the substrate in a heat treatment apparatus and heating the substrate until the temperature of the substrate is stabilized, and setting the temperature of the substrate heated by the heating step to a peripheral edge of the substrate. A measurement step of measuring at five or more points in the vicinity, and a minimum / maximum specifying at least one of a minimum temperature point corresponding to the lowest temperature or a maximum temperature point corresponding to the highest temperature measured in the measurement step A temperature location specifying step, including one of the lowest temperature location or the highest temperature location specified in the lowest / temperature location specifying step, and along the periphery of the substrate; The characterized by comprising a measurement point determination step of determining the perimeter measurement points near the peripheral edge of the substrate at equal intervals.

The temperature of the substrate is measured at a large number of points, and the peripheral measurement points are determined from these points so as to include at least one of the lowest temperature point and the highest temperature point and to be evenly spaced on the substrate along the peripheral edge of the substrate. Therefore, accurate temperature measurement in consideration of the temperature distribution of the substrate can be performed. That is, since accurate temperature measurement can be performed without necessarily having a large number of peripheral measurement points, the labor for temperature measurement during heat treatment is reduced.

[0020]

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

FIGS. 1 and 2 are a partial sectional view and a perspective view, respectively, of a vertical heat treatment apparatus according to the present invention.

As shown in FIG. 1, the vertical heat treatment apparatus according to the present invention comprises an inner tube 2a and an outer tube 2b made of quartz, for example.
The reaction tube 2 has a double-tube structure, and a metal tubular manifold 21 is provided below the reaction tube 2.

The inner tube 2a has an open upper end, and is supported inside the manifold 21. The outer tube 2b has an upper end closed, and a lower end is hermetically joined to an upper end of the manifold 21 below the base plate 22.

In the reaction tube 2, as shown in FIG.
A large number of, for example, 150 semiconductor wafers W (product wafers) forming a processing target (processing target substrate) are placed on a wafer boat 23 as a holder at a vertical interval in a shelf state in a horizontal state. The wafer boat 23 is held on a lid 24 via a heat insulating cylinder (heat insulator) 25. The wafer boat 23 has a product wafer W as a substrate to be processed.
In order to place the wafer in a heating atmosphere as uniform as possible, wafers for continuous placement called side wafers are placed on the upper end side and the lower end side, and monitor wafers for monitoring the processing state are scattered. For this reason, in addition to product wafers, grooves are provided in a number that allows for these wafers.
In the case where zero product wafer W is mounted, 170
A number of holding grooves are formed. The lid 24 is mounted on a boat elevator 26 for loading and unloading the wafer boat 23 into and out of the reaction tube 2. When the lid 24 is at the upper limit position, the lower end opening of the manifold 21, that is, the reaction tube 2 and the manifold 21 has a role of closing the opening at the lower end of the processing container constituted by the processing container 21.

A heater 3 made of, for example, a resistance heater is provided around the reaction tube 2. Heater 3 is in zone 1
The heaters 31 to 35 can independently control the amount of heat generated by the power controllers 41 to 45. In this example, a heating furnace is constituted by the reaction tube 2, the manifold 21, and the heater 3.

An inner temperature sensor S such as a thermocouple is provided on the inner wall of the inner tube 2a so as to correspond to each of the zones 1 to 5 of the heaters 31 to 35.
1 in to S5 in are installed. Outside temperature sensors S1out to S5out such as thermocouples are provided on the outer wall of the outer tube 2b in correspondence with the zones 1 to 5 of the heaters 31 to 35, respectively. Although not shown, the temperature sensor S1
A plurality of in to S5in and S1out to S5out are arranged along the circumferential direction of the inner tube 2a and the outer tube 2b, respectively. As a result, the temperature distribution in both the axial direction and the circumferential direction of the reaction tube 2 can be measured.

The above-described monitor wafer includes heaters 31 to 35
Are provided as monitor wafers W1 to W5 at positions corresponding to the respective zones 1 to 5. Normally, the same wafer as the product wafer is used as the monitor wafers W1 to W5, and the temperatures of a central measurement point located near the center of the wafer and a plurality of peripheral measurement points located near the periphery are monitored.

FIG. 3 shows the positional relationship between the central measuring point and the peripheral measuring point on the monitor wafers W1 to W5. The location c located near the center on the monitor wafers W1 to W5 is the central measurement location c, and the other locations e1 to e4 arranged on the periphery of the monitor wafer are the peripheral measurement locations e1 to e4.
The details of the method for determining the peripheral measurement point will be described later.

As will be described later, the center measurement point c and the peripheral measurement points e1 to e4 of the monitor wafers W1 to W5, respectively.
Are temperature sensors S1in to S5in, S1out
To S5out.

A plurality of gas supply pipes are provided in the manifold 21 so as to supply gas into the inner pipe 2a.
FIG. 1 shows two gas supply pipes 51 and 52 for convenience. The gas supply pipes 51 and 52 are provided with flow rate adjusters 61 and 62 such as a mass flow controller and a valve (not shown) for adjusting a gas flow rate, respectively. Further, an exhaust pipe 27 is connected to the manifold 21 so as to exhaust air from a gap between the inner pipe 2a and the outer pipe 2b, and the exhaust pipe 27 is connected to a vacuum pump (not shown). A pressure adjusting unit 28 for adjusting the pressure in the reaction tube 2 including, for example, a butterfly valve and a valve driving unit is provided in the exhaust pipe 27.

This vertical heat treatment apparatus includes a controller 100 for controlling processing parameters such as the temperature of the processing atmosphere in the reaction tube 2, the pressure in the reaction tube 2, and the gas flow rate. The controller 100 includes a temperature sensor S
The temperature measurement signals from 1in to S5in and S1out to S5out are input, and the power controller 41 of the heater 3 is input.
To 45, the pressure control unit 28, and the flow control units 61 and 62.

Before describing further details of this embodiment,
The tendency of the temperature distribution on the semiconductor wafer and its cause will be described.

In the heat treatment, there is a possibility that a temperature difference occurs near the center (center measurement point) and the periphery (perimeter measurement point) of the semiconductor wafer, and the temperature difference also occurs near the periphery due to the difference in the direction from the center of the semiconductor wafer. Differences can occur.

The reason that the temperature differs depending on the peripheral measurement point is that the thermal characteristics of the heat treatment apparatus for performing the heat treatment are not necessarily point-symmetrical when viewed from the center axis of the semiconductor wafer W. For example, a temperature distribution occurs due to the positional relationship between the openings of the gas supply pipes 51 and 52 and the semiconductor wafer.

FIG. 4 shows this relationship. 4A and 4B show the temperatures at the central measurement point c and the peripheral measurement points e1 to e5 of the monitor wafer W and the gas supply ports 510 and 5 when the temperature is stable.
FIG. 9 is a diagram illustrating an example of a positional relationship between the monitor wafer W and an upper surface of the monitor wafer W. Gas supply pipe 5
1, 52 opening portions 510 and 520 are opened on the side of the peripheral edge measurement point e1. The temperature of the supplied gas is lower than the temperature of the atmosphere in the reaction tube 2. Therefore, the peripheral measuring point e
The temperature of 1 is lower than the temperatures of the other peripheral measurement points e2 to e4. The peripheral measurement point e3 where the temperature is maximum at the substrate peripheral edge is located on the opposite side of the gas supply ports 510 and 520.

A temperature distribution may exist at the periphery of the substrate even when the temperature is stable as described above. And
This factor is not necessarily limited to the supply and flow of such a gas, and if anything disturbs the symmetry with respect to the central axis of the semiconductor wafer, there is a possibility that a temperature distribution may occur at the periphery of the substrate.

Next, the temporal variation of the temperature distribution of the semiconductor wafer W will be described. FIG. 5 is a graph showing a temporal change in temperature at the center measurement point c and the peripheral measurement points e1 and e3 in FIG. Here, it is assumed that the peripheral measurement point e1 is less likely to be heated and cooler than the peripheral measurement point e3 for some reason.

In FIG. 5, Tw represents a target temperature profile of the semiconductor wafer W, which is expressed as a heat treatment condition (heating rate, set temperature (Tsp), processing time, cooling rate) in a processing recipe described later. I have. Tc is the temperature of the central measurement point c (hereinafter, referred to as “central temperature”);
Te1 and Te2 represent the respective temperatures of the peripheral measurement points e1 and e2 (hereinafter referred to as “peripheral temperatures”).

The heat treatment step includes a heating step from time t1 to t2, a stabilization step from time t2 to t3, and a time step from t3 to t4.
And a temperature lowering step from time t4 to time t5. Then, in the process step, gas is introduced as necessary, and as a result, film formation and the like are performed. Hereinafter, the time variation of the temperature distribution at this time will be described in detail.

(1) Heating Step (Times t1 to t2) In the heating step, a large output is applied to the heater 3 so that the temperature of the semiconductor wafer rises.

At time t1, there is almost no difference between the center temperature Tc and the peripheral temperatures Te1 and Te3, but as the temperature rises, the temperature difference therebetween increases. Since the heater 3 is located at the periphery of the semiconductor wafer, and the semiconductor wafer is heated from the periphery, the peripheral temperatures Te1 and Te3 rise first, and the central temperature Tc rises later.
At this time, the peripheral edge measurement point e3 is relatively easily heated even in the peripheral edge, so that the temperature rise speed is high. That is,
In the heating process, the temperature difference between the central measurement point c and the peripheral measurement point e3 is large on the semiconductor wafer.

(2) Stabilization Step (Times t2 to t3) In the stabilization step, the output of the heater 3 is reduced.
However, the temperature rise of the semiconductor wafer does not stop immediately due to thermal inertia. For this reason, it takes some time until the temperature of the semiconductor wafer is stabilized. Therefore, the execution of processes such as film formation is postponed until the temperature of the semiconductor wafer is stabilized at the set temperature Tsp.

At this time, the peripheral measuring point e3 temporarily exceeds the set temperature Tsp and has a peak (overshoot) because the peripheral measuring point e3 is easily heated. Thereafter, the temperature temporarily drops below the set temperature (undershoot), and then settles to the set temperature Tsp. Since the peripheral measurement point e1 is less likely to be heated than the peripheral measurement point e3, the peripheral temperature Te1 is lower than the peripheral temperature Te3, but tends to change substantially similarly to the peripheral temperature Te3.

On the other hand, the central temperature Tc tends to gradually approach the set temperature Tsp without having a peak as a result of the temperature rising relatively slowly.

(3) Process Step (Times t3 to t4) In the process step, the temperature of the semiconductor wafer is relatively stable. However, as shown in FIG. 4 as an example, the temperature distribution still exists on the substrate at this time, and the peripheral temperature e1 has not reached the set temperature Tsp.

(4) Temperature Lowering Step (t4 to t5) In the temperature lowering step, the output of the heater 3 is further reduced. As a result, the temperature of the semiconductor wafer W decreases.

However, due to thermal inertia, the temperature of the semiconductor wafer decreases with a delay from the target temperature profile Tw. At this time, the temperatures of the peripheral measurement points e1 and e3 decrease more rapidly than those of the central measurement point c because heat radiation proceeds from the peripheral edge of the semiconductor wafer. E1 among peripheral measurement points
The temperature falls fastest because heat is easily dissipated. On the other hand, since the central measurement point c is mainly dissipated by conducting heat to the periphery, the temperature decreases with a delay to the periphery measurement points e1 and e3.

That is, in the temperature lowering step, the central measuring point c
The temperature difference between the semiconductor wafer and the peripheral measurement point e1 is large.

Next, further details of the heat treatment apparatus according to the present invention will be described.

FIG. 6 is a block diagram showing details of a portion related to the control of the heater 3 in the internal configuration of the controller 100. As shown in FIG. 6, the controller 100 is roughly divided into a substrate temperature estimating unit 110, a representative temperature / temperature difference calculating unit 120 for calculating a representative temperature representing a substrate such as a semiconductor wafer and a temperature difference in the substrate, a heater output control. It comprises a unit 130. The heater output control unit 130 further includes a heater output deriving unit 134 to which a processing recipe storage unit 132 is connected, and a heater output correction unit 138 to which a temperature difference allowable range storage unit 136 is connected.

FIG. 7 is a flowchart showing a control procedure of the heater 3 by the controller 100. Hereinafter, the procedure of temperature control will be described based on this flowchart.

(A) When the heat treatment process is started (S201), the temperature sensors Sin (S1in to S5i)
n), measurement signals of Sout (S1out to S5out) are read by the substrate temperature estimating unit 110 (S20).
2).

(B) The substrate temperature estimating unit 110 uses the measurement signals from the temperature sensors Sin and Sout to
The center temperature T1c to T5c and the peripheral temperature T1e to T5e of each W5 are estimated (S203).

For this estimation, the following equations (1) and (2) known in control engineering can be used.

X (t + 1) = A · x (t) + B · u (t) Equation (1) y (t) = C · x (t) + u (t) Equation (2) t: time x (t): n-dimensional state vector y (t): m-dimensional output vector u (t): r-dimensional input vector A, B, C: constants of n × n, n × r, m × n, respectively Is a matrix.

Equation (1) is called a state equation, and equation (2) is called an output equation. By simultaneously solving equations (1) and (2), an output vector y (t) corresponding to the input vector u (t) is obtained.
(T) can be obtained.

In this embodiment, the input vector u
(T) denotes temperature sensors S1in to S5in, S1out to
S5out is a measurement signal, and the output vector y (t) has a center temperature T1c to T5c and a peripheral temperature T1e to T5e.
It is.

In equations (1) and (2), the temperature sensor S
in, Sout measurement signal, central temperature Tc, peripheral temperature T
e has a multi-input / output relationship. That is, each of the zones 1 to 5 of the heater 3 does not independently affect each of the monitor wafers W1 to W5, and the heater of one zone has any influence on any of the monitor wafers.

Equations of state and the like are expressed by equation (3) taking noise into account,
(4) x (t + 1) = Ax (t) + Buu (t) + Ke (t) Expression (3) y (t) = Cx (t) + Du (t) + e (T) Expression (4) can also be used.

Here, t: time x (t): n-dimensional state vector y (t): m-dimensional output vector u (t): r-dimensional input vector e (t): m-dimensional noise vector A, B, C , D, K: n × n, n × r, mx, respectively
It is a constant matrix of n, m × m, and n × m.

As a method of obtaining the constant matrices A, B, C, and D determined by the thermal characteristics of the heat treatment apparatus, for example, a subspace method can be applied.

Specifically, the temperature sensors S1in to S5i
n, the measured signal of S1out to S5out and the central temperature T
1c to T5c and the data of the peripheral temperatures T1e to T5e are obtained,
(Manufacturer: The MathWorks. Inc., sales: Cybernet System Co., Ltd.) allows constant matrices A, B, and C to be back calculated.

This data acquisition is performed by gradually changing the outputs of the heaters 31 to 35 to obtain the temperature sensors S1in to S5in,
Measurement signals of S1out to S5out and central temperature T1c
To T5c and the temporal variations of the peripheral temperatures T1e to T5e at the same time. Central temperature T1c ~
The measurement of T5c and the peripheral temperatures T1e to T5e can be performed using a monitor wafer provided with a thermocouple.

Usually, a plurality of combinations of the obtained constant matrices A, B, C, and D exist. From this combination,
Central temperature T1c to T5c and peripheral temperature T1e to T5e
Is selected (the model (3) and (4) are calculated simultaneously) and the measured value matches (model evaluation).

When the combinations of the constant matrices A, B, C, and D are determined, the equations (1) and (2) or the equations (3) and (4) are simultaneously solved to obtain the temperature sensors S1in to S5in. S
From the measurement signal of 1out to S5out, the central temperature T1c to
T5c and the peripheral temperatures T1e to T5e can be calculated.

(C) The representative temperature / temperature difference calculator 120 calculates
Based on the central temperatures T1c to T5c and the peripheral temperatures T1e to T5e, representative temperatures T1r to T5r representing the temperatures of the monitor wafers W1 to W5 and temperature differences ΔT1 to ΔT5 of the monitor wafers W1 to W5 are calculated (S20).
4).

The calculation of the representative temperature Tr can be performed, for example, by the following equation (5).

Tr = Tc · x + Te (av) · (1-x) Expression (5) where Te (av): average value of peripheral temperature (hereinafter, referred to as “average peripheral temperature”) x: weight (0) <X <1), and Te (av) is obtained by the following equation (6). Te (av) = [ΣTe (i)] / n Equation (6)

Here, Σ: sum symbol Te (i): temperature of the peripheral measuring point ei on the same monitor wafer n: number of peripheral measuring points on the same monitor wafer.

That is, the representative temperature Tr is obtained by calculating an average value of the temperatures at a plurality of peripheral measurement points, and weighting and averaging the average value (average peripheral temperature) and the temperature at the central measurement point.
Is calculated.

The reason why the average value of the temperatures at the plurality of peripheral measurement points is obtained is that the temperature distribution at the peripheral measurement points is considered.

The meaning of the representative temperature Tr will be described in more detail with reference to the drawings.

FIGS. 8A and 8B are graphs showing the frequency distribution of the temperature on the semiconductor wafer. 8A and 8B, the representative temperatures are set to Tr1 and Tr2, respectively. The horizontal axis of the graph is temperature, and the vertical axis is frequency. The frequency is a value proportional to the area of the semiconductor wafer or the number of chips when the semiconductor wafer is equally divided vertically and horizontally. That is, the fact that the frequency at a certain temperature is large means that the area at that temperature occupies a large area on the semiconductor wafer.

As shown in FIGS. 8A and 8B, the temperature distribution on the semiconductor wafer W has a mountain-shaped distribution. Therefore, when the representative temperature Tr1 is set near the center of the distribution as shown in FIG. 8A,
It can be seen that a larger number of chips can be ensured within the same temperature width ± Δ than when it is off the center of the distribution shown in FIG. 8B.

By taking the average value of the temperatures at a plurality of peripheral measurement points, it is possible to prevent the representative temperature from deviating from the center of the temperature distribution. For example, if the comparatively low temperature region near the peripheral edge of the wafer is not included in the peripheral measurement point, the calculated representative temperature deviates from the center of the temperature distribution to the higher temperature side as shown in FIG. 8B.

In weighting and averaging the average peripheral temperature Te (av) and the central temperature, the weight x can be, for example, 1/3. More suitably, the temperature is set in consideration of the temperature distribution of the semiconductor wafer so that the representative temperature is located at the center of the temperature distribution.

The temperature difference ΔT can be calculated, for example, by the following equation (7).

ΔT = MAX (| Te1-Tc |, | Te2-Tc |, | Te3-Tc |, | Te4-Tc |) Expression (7) That is, the peripheral temperatures Te1, Te2, Te3, Te4 and the center The one having the largest absolute value among the temperature differences of the temperatures Tc is selected.

As shown in FIG. 5, when it is known that the temperature difference between the peripheral measuring point e3 at the time of temperature rise and the peripheral measuring point e1 at the time of temperature drop is the largest at the central measuring point c, the following is obtained. The temperature difference ΔT may be calculated by the equations (8) and (9).

At the time of temperature rise: ΔT = Te3−Tc Expression (8) At the time of temperature decrease: ΔT = Te1-Tc Expression (9) (D) The heater output deriving unit 134 calculates the representative temperatures T1r to T
The output values h1 to h5 of the heaters 31 to 35 should be derived based on 5r and the processing recipe (S205).

The processing recipe is, for example, a table showing the heat treatment conditions (heating rate, set temperature (Tsp), processing time, cooling rate, type of gas used, flow rate, etc.). The processing recipe is stored in the processing recipe storage unit 132. The heating rate, the set temperature, the processing time, the cooling rate, and the like may be represented as a target temperature profile Tw on the processing recipe as a function of time as shown in FIG.

For the heater output values h1 to h5, for example, the heater output values h1 to h5 are determined in advance based on, for example, a heating rate (rate) and a cooling rate (rate), and whether or not the representative temperature Tr has reached the set temperature Tsp is determined. By switching the heater output value according to the above, it can be derived from the target temperature profile Tw and the representative temperature Tr. In addition, for example, the difference between the target temperature profile Tw and the representative temperature Tr (Tw-Tr)
The heater output value may be determined to change continuously.

(E) The heater output correction section 138
It is determined whether the temperature differences ΔT1 to ΔT5 are within the allowable range (S206), and if the temperature difference is outside the allowable range, the heater output values h1 to h5 are corrected (S207).

The allowable range of the temperature difference is stored in the temperature difference allowable range storage section 136. The allowable range of the temperature difference is a function of the temperature as shown in the graph of FIG. In the graph of FIG. 9, the horizontal axis represents the representative temperature Tr, and the vertical axis represents the allowable range ΔTpe of the temperature difference.
represents r. When the temperature of the line A rises, the line B
Represents the allowable range ΔTper of the temperature difference at the time of temperature decrease. It can be seen that the larger the representative temperature Tr, the smaller the absolute value of the allowable range ΔTper.

The allowable range ΔTper indicates a range in which a slip line does not easily occur. The slip line is
It is assumed to be caused by shear stress in the semiconductor wafer.
Therefore, by suppressing the temperature difference on the semiconductor wafer that contributes to the shear stress to a certain value or less, the occurrence of slip lines can be reduced.

From the representative temperature Tr, an allowable range ΔTper (Tr) of the temperature difference at that time is obtained. If the temperature difference ΔT exceeds the allowable range ΔTper (Tr), the heater output values h1 to h5 derived in step S205 are corrected. That is, the heater output values h1 to h5 are corrected so as to reduce the heating rate or the cooling rate.

If the temperature difference ΔT is within the allowable range ΔTper, the heater output values h1 to h5 derived in step S205 are directly used for controlling the heater output.

(F) The heater output correction section 138 outputs the finally determined heater output values h1 to h5 to the power controllers 41 to 45 as control signals (S208), and the outputs of the heaters 31 to 35 are controlled. Is done.

(G) If the heat treatment process has not been completed, the process returns to step S202 and the temperature control of the semiconductor wafer W is continued (S209, S210).

Note that steps S202 to S209
Is repeated in a cycle of about 1 second to 4 seconds in many cases.

Next, FIG. 10 shows a temporal change in the temperature of the semiconductor wafer when the heat treatment is performed by the process shown in FIG.

FIG. 10A is a graph showing the temporal change of the representative temperature of the semiconductor wafer, and FIG. 10B is a graph showing the temporal change of the heater output.

In FIG. 10A, Tw represents a target temperature profile, and Tr is a representative temperature.

(1) Until time t1, the heater output is kept at P3 corresponding to the holding temperature T0. Temperature rise starts at time t1, and the heater output is increased from P3 to P6. Normally, this heater output should be maintained until the temperature raising process end time t6.

However, at time t2, the temperature difference Δ
Since T exceeds the allowable range ΔTper, the heater output is reduced from P6 to P5, and as a result, the heating rate is reduced.

At time t3, since the temperature difference ΔT falls within the allowable range ΔTper, the heater output is increased again to P6, and the temperature increase rate is increased again.

From time t4 to time t5, since the temperature difference ΔT has exceeded the allowable range, the heater output drops again to P5, and the rate of temperature rise decreases.

From time t5 to time t6, since the temperature difference ΔT is within the allowable range ΔTper, the heater output increases to P6.

Then, since the representative temperature reaches the set temperature Tsp at time t6, the output of the heater is reduced to an output P4 sufficient to maintain the set temperature Tsp.

(2) At time t7, the temperature lowering step is started, and the heater output is reduced to the output P1 for rapid temperature lowering. Then, from time t8 to t9, and time t10
From t to t11, since the temperature difference ΔT has exceeded the allowable range, the heater output is increased to P2, and the temperature lowering rate decreases accordingly.

From time t9 to t10, from time t11 to t1
At 2, the heater output is reduced to P1 for rapid temperature drop.

Since the representative temperature Tr has reached the holding temperature T0 at time t12, the heater output becomes the holding temperature T0.
Is again raised to an output P3 suitable for maintaining

As described above, the heater output is controlled by the representative temperature Tr, the temperature difference ΔT, the target temperature profile Tw, and the allowable range ΔTper of the temperature difference.

The heater output is switched according to the relationship between the representative temperature Tr and the target temperature profile Tw, and whether or not the temperature difference ΔT is within the allowable range ΔTper. This switching may be performed in a binary manner as described above, or may be performed in a stepwise manner depending on the degree of deviation from the allowable range or the like.

Next, a method for determining the peripheral measuring point will be described.

FIG. 11 is a flow chart showing a procedure for determining a peripheral measurement point.

First, a semiconductor wafer for measuring a peripheral edge measurement point is placed in a heat treatment apparatus, and the semiconductor wafer is heated according to predetermined heat treatment conditions (S302).

Then, after the temperature of the semiconductor wafer is stabilized, the temperature is measured at a number of measurement points set near the periphery of the semiconductor wafer (S304).

The measurement points can be set at equal intervals on a concentric circle along the periphery of the semiconductor wafer as shown in FIG. 12A, for example. The number of measurement points is not particularly limited as long as it is plural, but for example, 5 or more, 8 or more, 16 or more can be selected.

In some cases, measurement points may be set on a plurality of concentric circles as shown in FIG. 12B. As a method of measuring the temperature, for example, a temperature sensor such as a thermocouple may be provided on a semiconductor wafer.

The lowest temperature point where the temperature is the lowest and the highest temperature point where the temperature is the highest are selected from the measurement points (S306).

Finally, a peripheral edge measurement point is determined so as to include at least one of the lowest temperature point and the lowest temperature point (S308).

Since either the lowest temperature point or the lowest temperature point is included in the peripheral measurement point,
Even if the number of peripheral measurement points is small, it is easy to measure the peripheral temperature accurately reflecting the temperature distribution.

The peripheral measuring points are preferably set so as to be symmetrical with respect to the center of the semiconductor wafer, and are preferably determined so as to be substantially equally spaced on the semiconductor wafer. Further, it is particularly preferable that both the lowest temperature point and the highest temperature point are included, and the distance between them is determined to be equal. By doing so, it becomes possible to measure the peripheral temperature that more accurately reflects the temperature distribution of the semiconductor wafer.

The above embodiments of the present invention can be extended and modified within the scope of the technical idea of the present invention.

For example, the substrate is not limited to a semiconductor wafer, but may be, for example, a glass substrate.

The heat treatment apparatus is not limited to a vertical heat treatment furnace, and the purpose of the heat treatment is diffusion, annealing, formation of a thermal oxide film, and CVD (Chemical Vapor Depo).
deposition (for example, deposition of SiN or the like)
It does not matter which one of these.

The heaters need not be divided,
The number of sections is not limited to five. Further, it is not always necessary to always use both the representative temperature and the temperature difference for controlling the heater, but it is also possible to use only one of them.

Center temperature T1c to T5c and peripheral temperature T
1e to T5e are temperature sensors S1in to S5in, S1
Instead of estimating from the measurement signals of out to S5out, direct measurement may be performed. For this measurement, for example, (a) a temperature sensor such as a thermocouple is connected to the monitor wafers W1 to W
5, or (b) non-contact measurement using a radiation thermometer or the like can be used. At this time, the measurement signals of the temperature sensors S1in to S5in and S1out to S5out may be omitted in some cases.

[0120]

As described above, according to the present invention,
A heat treatment apparatus, a method of controlling the heat treatment apparatus, which enables the heat treatment of the substrate in consideration of the temperature distribution on the substrate,
In addition, a method for determining a location on the semiconductor wafer where the temperature is measured can be provided.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating a vertical heat treatment apparatus according to the present invention.

FIG. 2 is a perspective view illustrating a vertical heat treatment apparatus according to the present invention.

FIG. 3 is a top view showing a positional relationship between a center measurement point and a peripheral measurement point on a semiconductor wafer.

FIG. 4 is a top view and a partial cross-sectional view illustrating a positional relationship between an opening of a gas supply pipe and a semiconductor wafer.

FIG. 5 is a graph showing a temporal change of a central temperature and a peripheral temperature on a semiconductor wafer.

FIG. 6 is a block diagram illustrating details of a controller of the heat treatment apparatus according to the present invention.

FIG. 7 is a flowchart showing a control procedure by a controller of the heat treatment apparatus according to the present invention.

FIG. 8 is a graph showing a frequency distribution of a temperature on a semiconductor wafer.

FIG. 9 is a graph showing an allowable range of a temperature difference on a semiconductor wafer.

FIG. 10 is a graph showing a temporal change of a representative temperature of a semiconductor wafer together with a temporal change of a heater output when a heat treatment is performed by a heat treatment apparatus according to the present invention.

FIG. 11 is a flowchart showing a procedure for determining a peripheral measurement point.

FIG. 12 is a top view illustrating measurement points on a semiconductor wafer when a peripheral measurement point is determined.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Controller 110 Substrate temperature estimation unit 120 Representative temperature / temperature difference calculation unit 130 Heater output control unit 132 Processing recipe storage unit 134 Heater output derivation unit 136 Temperature difference allowable range storage unit 138 Heater output correction unit 2 Reaction tube 2a Inner tube 2b Outside Pipe 21 Manifold 22 Face plate 23 Wafer boat 24 Lid 26 Boat elevator 27 Exhaust pipe 28 Pressure regulator 3, 31-35 Heater 41-45 Power controller 51, 52 Gas supply pipe 510, 520 Opening 61, 62 Flow rate Adjustment unit Sin, Sout Temperature sensor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fujio Suzuki 1-2-41 Machiya, Shiroyama-cho, Tsukui-gun, Kanagawa Prefecture Inside the Sagami Office of Tokyo Electron Tohoku Co., Ltd. F3 term in Tokyo Electron Co., Ltd. (reference) 4K056 AA09 BA01 BB03 CA18 FA04 FA13 5F045 AA03 AA20 BB02 DP19 EK06 EK22 GB05

Claims (12)

[Claims] 1. A heat treatment apparatus for arranging a substrate in a processing chamber and performing heat treatment, comprising: a heating unit for heating the substrate from the periphery of the substrate; a central measurement point located near a center of the substrate; A temperature measuring unit that measures the temperature of a plurality of peripheral measurement points located near the periphery of the substrate; and, based on the temperatures of the central measurement point and the plurality of peripheral measurement points measured by the temperature measuring unit, A heat treatment apparatus comprising: a representative temperature calculation unit that calculates a representative temperature; and a control unit that controls the heating unit based on the representative temperature calculated by the representative temperature calculation unit. 2. The representative temperature calculating section calculates the representative temperature by weighting and averaging the average value of the temperatures of the plurality of peripheral measurement points and the temperature of the central measurement point. Item 2. The heat treatment apparatus according to Item 1. 3. The heating unit includes at least a divided first heater and a second heater, and the temperature measuring unit is disposed corresponding to each of the first heater and the second heater. Measuring the temperatures of the first substrate and the second substrate, respectively, wherein the representative temperature calculation unit calculates the temperature of the first substrate and the second substrate.
Calculating the representative temperature of each of the substrates, wherein the control unit controls the first heater and the second heater based on the representative temperatures of the first substrate and the second substrate. The heat treatment apparatus according to claim 1, wherein 4. A heat treatment apparatus for performing heat treatment by arranging a substrate in a processing chamber, comprising: a heating unit for heating the substrate from a periphery of the substrate; A temperature measurement unit that measures the temperature of a plurality of peripheral measurement points located near the periphery of the substrate; and a temperature that calculates a temperature difference in the substrate based on the temperature of the central measurement point and the temperatures of the plurality of peripheral measurement points. A heat treatment apparatus comprising: a difference calculation unit; and a control unit that controls the heating unit based on the temperature difference calculated by the temperature difference calculation unit. 5. The heat treatment apparatus according to claim 4, wherein the control unit controls the heating unit such that the temperature difference falls within a predetermined allowable range. 6. The heat treatment apparatus according to claim 5, wherein the allowable range changes according to a temperature of the substrate. 7. The temperature difference calculating section calculates the temperature difference by selecting a difference having a maximum absolute value from a temperature difference between the center measurement point and the plurality of peripheral measurement points. The heat treatment apparatus according to claim 4. 8. The temperature measuring section includes: (1) a plurality of temperature measuring means installed in the heat treatment apparatus in a non-contact state with the substrate; Estimating means for estimating the temperature of the measurement point; (2) Consisting of temperature measuring means installed on a substrate placed in the heat treatment apparatus; The heat treatment apparatus according to claim 1, wherein: 9. A method for controlling a heat treatment apparatus for performing a heat treatment on a substrate, comprising: measuring a temperature of a central measurement point located near a center of the substrate and a plurality of peripheral measurement points located near a periphery of the substrate. A temperature measuring step of measuring; a representative temperature / temperature difference calculating step of calculating a representative temperature of the substrate and a temperature difference in the substrate based on the temperature of the central measurement point and the temperatures of a plurality of peripheral measurement points; and the representative temperature A control step of controlling the heat treatment apparatus based on the representative temperature and the temperature difference calculated in the temperature difference calculation step. 10. A control parameter deriving step of deriving a control parameter of the heat treatment apparatus based on the representative temperature, and correcting the control parameter derived in the control parameter deriving step based on the temperature difference. And a control parameter correcting step for controlling the heat treatment apparatus. 11. A method for determining a plurality of peripheral measurement points for measuring a temperature at the time of heat-treating a substrate, the method comprising: arranging the substrate in a heat-treating apparatus. A heating step of heating the substrate until the temperature of the substrate is stabilized, a measuring step of measuring the temperature of the substrate heated in the heating step at five or more locations near the periphery of the substrate, A minimum / maximum temperature location identifying step for identifying at least one of the lowest temperature location corresponding to the lowest temperature or the highest temperature location corresponding to the highest temperature; and The edge measuring section near the periphery of the substrate so as to include either the lowest temperature point or the highest temperature point and to be evenly spaced on the substrate along the periphery of the substrate. Methods for determining the peripheral measurement portion of the substrate, characterized by comprising a measurement point determination step of determining. 12. The method according to claim 11, wherein the method is for use in the heat treatment apparatus according to claim 1. Description: