JP2002043301A - Heat treatment apparatus, method of heat-treating substrate, and medium in which treatment recipe is recorded - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat treatment apparatus with which uniform heat treatment of a substrate surface can be performed even if the stabilizing time for stabilizing the substrate temperature is shortened. SOLUTION: This heat treatment apparatus is controlled with a programmed temperature profile that represents a relation between elapsing time and programmed temperature, wherein the programmed temperature profile is specified so as to contain both a center high-temperature condition where the temperature of the central part of the substrate is higher under film deposition and a periphery high-temperature condition where the temperature of the peripheral part of the substrate is higher. Through mutual compensation between the center high-temperature condition and the periphery high-temperature condition, average temperature under film deposition in the peripheral part and that in the central part become close. As a result, uniform heat treatment is performed on the substrate surface even if the stabilizing time is shortened.

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, a heat treatment method for a substrate, and a medium on which a processing recipe is recorded, and more particularly to a heat treatment apparatus, a heat treatment method for a substrate, and a treatment method capable of reducing a waiting time for temperature stabilization. It relates to a medium on which a recipe is recorded.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, a vertical heat treatment apparatus for performing batch processing is one of apparatuses for performing heat treatment on a semiconductor wafer (hereinafter, referred to as a wafer). In this apparatus, a large number of wafers are held in a shelf shape by a holder called a wafer boat or the like, and the holder is loaded into a vertical heat treatment furnace and subjected to heat treatment, for example, oxidation treatment or CVD (Ch).
It performs an Electronic Vapor Deposition. When performing heat treatment with a vertical heat treatment device,
The wafer is carried into the processing chamber of the vertical heat treatment apparatus, and heated by a heater to raise the temperature. Then, after the temperature of the substrate is stabilized, a target heat treatment, for example, an oxidation treatment is performed.

[0003]

However, in the conventional heat treatment apparatus, in order to uniformly perform the heat treatment in the substrate surface,
This requires a stabilization time for the substrate temperature to stabilize.
For this reason, the heat treatment process takes time for the stabilization time, and the throughput is reduced. The present invention has been made to solve such a problem, and an object of the present invention is to provide a heat treatment apparatus capable of uniformly performing a heat treatment in a substrate surface even if the stabilization time is shortened.

[0004]

Means for Solving the Problems (1) In order to achieve the above object, the present invention comprises the following heat treatment apparatus. A heat treatment apparatus for performing heat treatment by disposing a substrate in a processing chamber, wherein the heating unit heats the substrate, and a gas introduction unit that introduces a processing gas for forming a film on the substrate into the processing chamber. The heating unit and the heating unit according to a processing recipe including at least a heat treatment step describing a heat treatment step of forming a film on the substrate, including a set temperature profile representing a relationship between a lapse of time and a set temperature. A control section for controlling a gas introduction section, wherein the central temperature near the center of the substrate is higher than the peripheral temperature near the peripheral edge during the heat treatment step, and the peripheral temperature of the substrate is higher than the central temperature. The set temperature profile is defined so that a peripheral high temperature state appears.

[0005] During the heat treatment step, both the central high-temperature state near the center of the substrate and the peripheral high-temperature state near the periphery of the substrate are high. By canceling out both the central high-temperature state and the peripheral high-temperature state, the central temperature and the peripheral temperature become closer with time averaging. As a result, even if the stabilization time is shortened, the heat treatment on the substrate surface can be easily performed uniformly.

Here, it is preferable that the set temperature profile is defined so that a time average value of the center temperature of the substrate during the heat treatment step is substantially equal to a time average value of the peripheral temperature. When the time average value of the center temperature is substantially equal to the time average value of the peripheral temperature, it is easy to ensure the uniformity of the heat treatment on the substrate surface. Note that the set temperature profile may be defined so that the set temperature during the heat treatment step is a time-change set temperature that changes with time.

(2) The heat treatment method for a substrate according to the present invention is configured as follows. Control the temperature according to the set temperature,
A method for performing a heat treatment of a substrate, comprising a heat treatment step of forming a film on the substrate in a processing gas atmosphere, wherein the heat treatment step is such that a central temperature near a center of the substrate is higher than a peripheral temperature near a peripheral edge of the substrate. A central high-temperature step; and a peripheral high-temperature step in which the peripheral temperature of the substrate is higher than the central temperature.

Since the central high-temperature state and the peripheral high-temperature state cancel each other, uniformity of the heat treatment in the substrate surface can be easily ensured even if the stabilization time is shortened. Here, the set temperature in the heat treatment step may decrease with the passage of time. At this time, if the substrate is heated and radiated from the periphery, the central high-temperature step is performed after the peripheral-edge high-temperature step. If the substrate is heated and radiated from the periphery of the substrate, the peripheral temperature of the substrate falls more rapidly than the center temperature as the set temperature falls with time.

[0009] Further, the time change set temperature in the heat treatment step may increase with time. At this time, if the substrate is heated and radiated from the periphery of the substrate, the peripheral high-temperature step is performed after the central high-temperature step. If the substrate is heated and radiated from the periphery of the substrate, the peripheral temperature of the substrate rises more quickly than the center temperature as the set temperature rises over time.

Here, it is preferable that the time average value of the central temperature of the substrate in the heat treatment step is substantially equal to the time average value of the peripheral temperature. This is because it leads to securing uniform heat treatment in the substrate surface. Here, the peripheral edge temperature may be an average value of the temperatures at a plurality of locations near the peripheral edge.

In the heat treatment step, it is preferable that the concentration and pressure of the processing gas are substantially constant with time. This is because uniform heat treatment in the substrate surface can be easily performed.

(3) The heat treatment method for a substrate according to the present invention may be configured as follows. A method for heat-treating a substrate, the method comprising: heating the substrate with a heat output in a first range to increase a central temperature near a center of the substrate and a peripheral temperature near a peripheral edge of the substrate; Heating the substrate from the substrate periphery with a second range of heat output smaller than the first range of heat output in a process gas atmosphere, thereby lowering the central temperature and the periphery temperature, A heat treatment step of forming a film on the substrate, and a heat treatment step including a central high temperature step in which the central temperature of the substrate is higher than the peripheral temperature and a peripheral high temperature step in which the peripheral temperature is higher than the central temperature. It is characterized by doing.

In a heat treatment step of forming a film while heating the substrate with the second heat output after the substrate is heated with the first heat output, the heat output and the like are adjusted so that a central high temperature state and a peripheral high temperature state are formed during the film formation. Both states can appear. As a result, even if the stabilization step between the temperature raising step and the heat treatment step (film formation step) is shortened or the stabilization step is not provided, it is easy to ensure the uniformity of the heat treatment in the substrate surface.

(4) The recording medium according to the present invention can be configured as follows. A recording medium recording a processing recipe for controlling a heat treatment apparatus for performing a heat treatment on a substrate, wherein the processing recipe includes a set temperature profile representing a relationship between a lapse of time and a set temperature, and A heat treatment step describing at least a heat treatment step for describing a heat treatment step of forming a film on the substrate, wherein during the heat treatment step, the central temperature near the center of the substrate is higher than the peripheral temperature near the periphery; Is characterized in that the set temperature profile is defined so that a peripheral high temperature state higher than the central temperature appears.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 are a cross-sectional view and a perspective view, respectively, of a vertical heat treatment apparatus according to the present invention. The vertical heat treatment apparatus includes a vertical heat treatment furnace 10, a wafer boat 20 as a wafer holder, a boat elevator 30 that moves the wafer boat 20 up and down, a control unit 100.
And

The vertical heat treatment furnace 10 is a heater 5 serving as a heating unit including a reaction tube 40 having a double structure made of, for example, quartz and a resistance heating element provided so as to surround the reaction tube 40.
0 and so on. A gas supply pipe 60 is provided at the bottom of the reaction pipe 40.
And the exhaust pipe 70 is connected to the outer pipe 4 of the reaction pipe 40.
The gas flows from 0a into the inner tube 40b through the gas hole 41. The gas flow rate in the gas supply pipe 60 is controlled by a flow rate controller 65, and the amount of exhaust from the exhaust pipe 70 is controlled by an exhaust rate controller 75. In addition, 45 is a soaking container.

In the wafer boat 20, for example, a plurality of columns 23 are provided between a top plate 21 and a bottom plate 22, and the peripheral edge of a wafer (substrate to be processed) W is inserted into a vertically formed groove in the columns 23. It is configured to hold the wafers W and thus hold the plurality of wafers W in a shelf shape. The wafer boat 20 has a lid 81 that opens and closes an opening 80 at the lower end of the vertical heat treatment furnace 10.
It is mounted on a heat retaining cylinder 82 provided above. The lid 81 is provided in the boat elevator 30, and when the boat elevator 30 moves up and down, the wafer boat 20 is carried in and out of the vertical heat treatment furnace 10.

The heater 50 includes five heaters 51 to 5
The zones (regions) 1 to 5 in the vertical heat treatment furnace 10 are mainly heated. Monitor wafers W1 to W5 for temperature monitoring are arranged at positions representative of zones 1 to 5, respectively. That is,
The monitor wafers W1 to W5 and the zones 1 to 5 correspond to each other on a one-to-one basis. The power consumption of the heaters 51 to 55 is individually controlled by power controllers 91 to 95, respectively.

The substrate temperatures of the monitor wafers W1 to W5 are not directly measured but are provided near the heater 50 (the outer wall of the heat equalizing vessel 45) and near the wafer W (the inner wall of the inner tube 40b). Temperature sensors Sout, Sin
Is estimated on the basis of the temperature measurement result. This is to prevent the wafer W from being contaminated with metal or the like by contacting the wafer W with a temperature sensor such as a thermocouple. The temperature sensors Sin and Sout correspond to the monitor wafers W1 to W5, respectively, and correspond to Sin1 to Sin5 and Sout1 to Sout.
out5 is installed. The control unit 100 controls the vertical heat treatment furnace 10 and includes a temperature sensor Sin1.
To Sin5 and Sout1 to Sout5, and outputs control signals to the power controllers 91 to 95, the flow controller 65, and the displacement controller 75.

FIG. 3 shows the internal configuration of the control unit 100.
FIG. 3 is a block diagram illustrating details of a portion related to control of a heater 3. As shown in FIG. 3, the control unit 100 includes a temperature sensor S1
in to S5in, central temperatures T1c to T5c near the center of monitor wafers W1 to W5, and peripheral temperature T1 near the peripheral edge estimated based on measurement signals from S1out to S5out.
e to T5e, the substrate temperature estimating unit 110, the central temperatures T1c to T5c of the respective monitor wafers W1 to W5,
From the peripheral temperatures T1e to T5e, each monitor wafer W
Based on the representative temperature calculator 120 for calculating the representative temperatures T1 to T5 of 1 to W5, the representative temperatures T1 to T5 of the monitor wafer, and the heater outputs h1 to h5 based on the set temperature profiles stored in the set temperature profile storage unit 130. It comprises a heater output determining unit 140 for determining. The heater outputs h1 to h5 determined by the heater output determining unit 140 are sent to the power controllers 91 to 95 as control signals.

The set temperature profile represents the relationship between the passage of time and the set temperature (the temperature at which the wafer W should be). One example is shown in FIG. FIG. 4 shows a set temperature profile according to the present invention as a graph showing a relationship between time and temperature.

(A) From time t0 to t1, the set temperature is maintained at T0. At this time, the wafer boat 20 holding the wafer W is carried into the vertical heat treatment furnace 10 (loading step). (B) Between time t1 and t2, the set temperature is the temperature T
It rises at a constant rate from 0 to T2 (heating step).

(C) Between time t2 and time t3, the set temperature is maintained at T2. Even if the actual temperature of the wafer W is constant, it takes some time until the temperature becomes constant due to thermal inertia. Therefore, it is not necessary to proceed to the next step until the wafer temperature is stabilized (stabilization step). In general, this stabilization step usually requires several minutes or more, and in some cases, tens of minutes. The present invention is characterized in that even if the stabilization time (t3−t2) is shortened or omitted, the quality of the wafer W is hardly deteriorated.

(D) Between time t3 and t4, the set temperature gradually decreases from T2 to T1. At this time, the processing gas such as oxygen gas is supplied from the gas supply pipe 60 to the vertical heat treatment furnace 1.
Then, heat treatment such as formation of an oxide film on a silicon wafer is performed (film forming step). That is, the set temperature during film formation is a time-change set temperature that changes with the passage of time. Note that the time change set temperature referred to here is one in which the set temperature undergoes some change during film formation, and the set temperature may temporarily become a constant value during film formation. That is, it can be said that the temperature is a time-change set temperature except that the set temperature is constant throughout the film forming process (heat treatment process). Hereinafter, the same shall be interpreted. According to the present invention, the stabilization time can be shortened by appropriately combining the temperature raising rate and the temperature change set temperature during film formation. The details will be described later.

(E) Between time t4 and time t5, the set temperature decreases from T1 to T0 at a constant rate (temperature decreasing step). (F) After time t5, the set temperature is maintained at T0. At this time, the wafer boat 20 holding the wafer W is carried out of the vertical heat treatment furnace 10 (unloading step).

As described above, in addition to (1) directly specifying the temperature in response to the passage of time,
Various expression methods are conceivable, such as (2) designating a rate of change in temperature such as a heating rate, or (3) designating a heater output. As a result, as long as the passage of time and the temperature of the wafer W are associated with each other, there is no need to be concerned with the apparent expression method.

The set temperature profile is a part of a processing recipe that determines the entire heat treatment process of the wafer W. In the processing recipe, in addition to the set temperature profile, processes such as discharge of the atmosphere from the inside of the vertical heat treatment furnace 10 and introduction of the processing gas are shown corresponding to the passage of time. The film formation step is particularly important in the entire heat treatment step, and a portion of the processing recipe that describes the film formation step is referred to as a film formation step description section.

FIG. 5 is a flowchart showing a control procedure of the heater 50 by the control unit 100. Hereinafter, the procedure of controlling the temperature of the vertical heat treatment furnace 10 will be described based on this flowchart. (A) When the heat treatment process is started, the temperature sensor S
in (S1in ~ S5in), Sout (S1out ~
The measurement signal of S5out) is read by the temperature estimating unit 110 (S201).

(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 (S202). This estimation includes the following equations (1) and (2) known in control engineering.
Can be used. x (t + 1) = Ax (t) + Buu (t) Formula (1) y (t) = Cx (t) + u (t) Formula (2) where t: time x (t): n-dimensional state vector y (t): m-dimensional output vector u (t): r-dimensional input vector A, B, C: constant matrix of n × n, n × r, m × n, respectively .

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 the present embodiment, the input vectors u (t) are temperature sensors S1in to S5in,
S1out to S5out are measured signals, and the output vector y (t) is the center temperature T1c to T5c and the peripheral temperature T
1e to T5e.

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 given 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
n, m × m, n × m constant matrix.

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 sensor S1
in to S5in, measurement signals of S1out to S5out and central temperatures T1c to T5c and peripheral temperatures T1e to T5
e, and obtains the data from, for example, software Matlab (manufactured by The MathWorks.
Inc. , Sales: Cybernet System Co., Ltd.), the constant matrices A, B, and C can be back calculated.

This data acquisition is performed by gradually changing the outputs of the heaters 51 to 55 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.

Generally, there are a plurality of combinations of the determined constant matrices A, B, C, and D. 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, Equation (1),
By simultaneously solving (2) or equations (3) and (4), the temperature sensors S1in to S5in, S1out to S5
The center temperature T1c to T5c and the peripheral temperature T1e to T5e can be calculated from the measurement signal of out.

(C) The representative temperature calculator 120 calculates the representative temperature T representing the temperatures of the monitor wafers W1 to W5 based on the central temperatures T1c to T5c and the peripheral temperatures T1e to T5e.
1r to T5r are calculated (S203). The calculation of the representative temperature Tr can be performed, for example, by the following equation (5). Tr = Tc.x + Te. (1-x) Formula (5) where x: weight (0 <x <1). The weight x is
In consideration of the temperature distribution on the wafer W, a value that makes the representative temperature Tr appropriate as a value representing the temperature of the wafer W is adopted. As the weight x, for example, a value of 1/3 can be adopted.

(D) The heater output determining section 130 determines the output values h1 to h5 of the heaters 51 to 55 based on the representative temperatures T1r to T5r and the set temperature profile (S20).
4). The heater output values h1 to h5 are, for example, set temperatures Ts
It can be determined according to the difference between p and the representative temperature Tr (Tsp-Tr). Alternatively, it may be determined according to a temperature change rate such as a temperature rising rate. (E) The heater output determination unit 140 outputs the finally determined heater output values h1 to h5 to the power controllers 91 to 95 as control signals (S205), and the outputs of the heaters 51 to 55 are controlled. . (F) If the heat treatment process has not been completed, the process returns to step S201, and the temperature control of the semiconductor wafer W is continued (S206). In addition, this step S202 to S2
06 is repeated in a cycle of about 1 second to 4 seconds in many cases.

Next, the details of the temperature control using the set temperature profile according to the present invention will be described. FIG. 6 is a graph showing a temporal change in the temperature on the wafer W when the set temperature profile shown in FIG. 4 is used. FIG. 6 (A)
Shows the temporal changes of the peripheral temperature Te near the peripheral edge of the wafer W and the central temperature Tc near the center corresponding to the set temperature Tsp. FIG. 6B shows a temporal change of the temperature difference ΔT (= Tc−Te) in the surface of the wafer W, and FIG.
Represents the temporal change of the output of the heater 50.

(1) The temperature is raised from time t1 to t2. At this time, the output of the heater 50 is increased from P1 to P4 due to rapid temperature rise. Since the heater 50 heats the wafer W from its periphery, the periphery temperature Te rises before the center temperature Tc. As a result, the temperature difference ΔT
Takes a negative value. That is, at this time, the peripheral temperature of the wafer W is higher than the central temperature. (2) From time t2 to t3, the set temperature is constant at T2, and the temperature of wafer W is stabilized. At this time, the output of the heater 50 is reduced from P4 to P3. However, the temperature rise of the wafer W does not stop immediately due to thermal inertia. Therefore, the temperature difference ΔT gradually approaches zero.

(3) From time t3 to t5, the set temperature gradually decreases from T2 to T1. The output of the heater 50 is reduced from P3 to P2. From time t3 to t
In the period up to 5, film formation (heat treatment) is performed by introducing a processing gas such as oxygen gas. As the set temperature decreases, the wafer W
Is also lower, but the peripheral temperature Te is higher than the central temperature Tc.
Tend to decrease rapidly. This is because heat is radiated from the periphery of the wafer W. That is, the wafer W
In the periphery of the wafer W, a change in temperature occurs before the center of the wafer W both during heating and during heat radiation.

At time t3, the temperature difference ΔT of the wafer W which has been in the high temperature state at the peripheral edge due to the temperature raising step from time t1 to t2 is still in the high temperature state at the peripheral edge. This is because the time (t3-t2) for the stabilization step is short. However, as the set temperature decreases, the peripheral temperature decreases before the center temperature. Therefore, the peripheral high-temperature state gradually shifts to the central high-temperature state in which the central temperature Tc is higher than the peripheral temperature Te. At time t4, the center temperature and the peripheral edge temperature become the same, and accordingly, the temperature difference ΔT becomes zero. Thereafter, the temperature becomes the central high temperature state, and the temperature difference ΔT becomes a stable state at ΔT2.

As described above, it is a feature of the present invention that both the central high-temperature state and the peripheral high-temperature state are taken during the film formation. This means that the film forming conditions at the center and the peripheral edge of the wafer W are close on average over time. That is, the average value of the film formation rate R (film growth rate) when the temperature changes during film formation can be expressed based on the time average T (Av) of the temperature. This is shown below.

The film thickness D of the film formed on the wafer is represented by the following equation (6) from the film formation rate (film growth rate) R and time t. D = ∫ _t3 ^t5 R (T) dt Formula (6) Here, ∫ is an integral symbol, and R (T) is a film formation rate R.
Is a function of the temperature T.

The film formation rate R (T) can be developed with a constant temperature value T0 as shown in the following equation (7). R (T) = R (T0) + R1 (T0) * (T−T0) Formula (7) Here, R1 (T0): dR (T0) / dt (time derivative of film formation rate).

By substituting equation (7) into equation (6), the following equation (8) can be derived. D = R (T0) * (t5−t3) + R1 (T0) * ∫ _t3 ^t5 (T−T0) dt Equation (8) Here, the time average value (average temperature) T (Av) of the temperature T is as follows: Is defined by the following equation (9). T (Av) = ∫ _t3 ^t5 T (t) dt / (t5−t3) Equation (9)

Then, if T0 = T (Av) in equation (8), the following equation (10) is obtained. D / (t5−t3) = R (T (Av)) Equation (10) where D / (t5−t3) is an average value of film formation rates during film formation (average film formation rate). . That is, Expression (10) means that the average film forming rate when the temperature changes during film forming is determined by the average temperature T (Av).

From the above, it can be seen that it is preferable that the time average value (average center temperature) Tc (Av) of the central temperature during film formation and the time average value (average peripheral temperature) Te (Av) of the peripheral temperature are close. The average center temperature Tc (Av) and the average peripheral temperature Te (Av) are expressed by the following equations. ^{_{Tc (Av) = ∫ t3 t5}} Tc (t) dt / (t5-t3) ...... formula (11) Te (Av) = ∫ t3 t5 Te (t) dt / (t5-t3) ...... formula (12)

Here, Tc (Av) = Te (Av) Equation (13) The following equation (14) can be derived. Ｔ _t3 ^t5 (Tc (t) −Te (t)) dt = 0 Equation (14) where Tc (t) −Te (t) is a temperature difference ΔT (t)
Because it is. ∫ _t3 ^t5 (ΔT (t)) dt = 0 Equation (15)

As described above, in order to form a film at the center and the periphery of the wafer W in the same manner, the average center temperature Tc during the film formation is required.
It can be seen that (Av) and the average peripheral temperature Te (Av) are preferably the same, that is, the integral value of the temperature difference ΔT (t) is preferably 0. This means that the area of the oblique line from time t3 to t4 in FIG. 6B is equal to the area of the oblique line from time t4 to t5.

As described above, as a result of shortening the time of the stabilization step, even if there is a temperature difference between the center temperature and the peripheral temperature at the beginning of the film forming step, the temperature difference is opposite to the temperature difference. Thus, the film thickness distribution at the center and the periphery of the wafer W can be made uniform.

However, considering conditions other than the temperature, it is not always the best condition for making the film thickness uniform that the average temperature of the center and the peripheral edge of the wafer W are equal. For example, in low pressure CVD, a relatively fresh processing gas tends to be supplied to the periphery of the wafer, and a consumed processing gas tends to be supplied to the vicinity of the center. That is, at this time, even if the temperature conditions are the same, the film thickness at the center of the wafer W tends to be small and the film thickness at the peripheral edge tends to be large. In this case, it is more preferable that the center temperature is somewhat higher than the peripheral temperature in order to improve the film thickness distribution in consideration of the unevenness of the processing gas conditions.

As described above, the relationship between the average center temperature and the average peripheral temperature is adjusted according to the heat treatment conditions applied to the wafer W. There are the following methods for adjusting the average peripheral temperature and the average central temperature.

The heating rate in the heating step (from time t1 to t2) is changed. When the heating rate is increased, the temperature difference between the peripheral temperature Te and the central temperature Tc during the heating increases. As a result, the average peripheral temperature in the subsequent film forming process becomes higher than the average central temperature. Conversely, when the heating rate is decreased, the temperature difference between the peripheral temperature Te and the center temperature Tc during the heating increases. As a result, since the temperature difference between the peripheral temperature Te and the central temperature Tc is small in the peripheral high-temperature state at the beginning of the film forming process, the central high-temperature state becomes superior to the peripheral high-temperature state in the entire film forming process. That is, the average peripheral temperature in the subsequent film forming process is lower than the average central temperature.

The time (t) of the stabilization step (t 2 to t 3)
3-t2) is changed. When the stabilization time is shortened, the temperature difference between the peripheral temperature Te and the central temperature Tc in the initial stage of the film forming process increases, so that the average peripheral temperature Te increases with respect to the average central temperature Tc. Conversely, if the stabilization time is lengthened, the average peripheral temperature Te decreases with respect to the average center temperature.

The time gradient ((T 2 −T 3) / (t 5) of the time change set temperature in the film forming process (time t 4 to t 5)
-T3)) is changed. If the time gradient of the set temperature is increased, the peripheral temperature decreases more rapidly than the central temperature. Then, the final temperature difference ΔT2 also increases. As a result, the average center temperature is higher than the average peripheral temperature. Conversely, if the time gradient of the set temperature is reduced, the temperature difference ΔT
2 becomes smaller, and the average center temperature tends to be smaller than the average peripheral temperature.

As described above, by changing the set temperature profiles in the temperature raising step, the stabilizing step, and the film forming step, the average center temperature and the average peripheral temperature in the film forming step can be controlled. (4) From time t5 to t6, the set temperature is from T1 to T0.
To decline. At this time, the introduction of the processing gas is stopped. After that, the wafer W is taken out of the vertical heat treatment furnace 10.

(Comparative Example) Next, as a comparative example, a case where the set temperature during film formation is a constant temperature set temperature profile is shown.

FIG. 7 is a graph showing a comparative example of the present invention. FIG. 7A shows the set temperature Tsp and the central temperature Tc,
FIG. 7 is a graph showing the lapse of time of the peripheral edge temperature Te,
(B) is a graph showing a temporal change of the temperature difference ΔT (= Tc−Te) at that time. As shown in FIG. 7A, the set temperature Tsp from time t3 to time t4 is constant, which is different from the set temperature profile shown in FIG. Since there is no particular difference from FIG. 6 until the stabilization step, the description is omitted.

In the film forming process from time t3 to t5, the value is T1 'at the steady set temperature, so that the peripheral temperature Te and the central temperature Tc gradually approach the temperature T1'. As a result, until the time t4, the peripheral temperature Te becomes the central temperature time Tc.
The temperature is higher than that of the peripheral edge, and thereafter, the temperatures of the two become substantially equal.

That is, the average peripheral temperature Te (Av) during film formation
Becomes higher than the average center temperature Tc (Av). For this reason, the temperature condition differs between the center and the peripheral edge of the wafer W, and it is difficult to guarantee the uniformity of the film thickness in the wafer surface. To avoid this, a longer stabilization time (t3−t2) should be taken.
Then, the heat treatment process takes a long time.

(Specific Experimental Example) As an example of a specific heat treatment, an oxide film was formed using oxygen as a processing gas. Table 1 summarizes the results.

[Table 1]

An oxide film was formed on the silicon wafer W by using three kinds of recipes of the heat treatment, ie, the recipe 1 and the recipe 2 of the set temperature of the comparative example, and the recipe 3 of the set time with the temperature as the embodiment. In each case, the temperature was raised to 900 ° C., and after a predetermined stabilization step at a set temperature of 900 ° C., a film forming step was performed.

In recipe 1, when the stabilization time was set to 5 minutes, the film thickness distribution in the wafer surface was 0.57%. Recipe 2
When the stabilization time was shortened to 1 minute, the film thickness distribution in the wafer surface deteriorated to 1.25%. In contrast, Recipe 3
Means that the stabilization time is 1 minute and the set temperature is 900
The film was formed at a time-change set temperature in which the temperature was gradually decreased from 889C to 889C. As a result, 0.5
% And a uniform film thickness distribution could be obtained.

(Modification) Next, a modification of the set temperature profile will be described. The following modifications can be performed using the heat treatment apparatus shown in FIGS. 1 to 3 described above.

FIG. 8 shows an example in which steps after the film forming step are changed. From time t0 to t5, there is no difference from FIG. After time t5, the temperature is raised to raise the set temperature Tsp to T2 again, and thereafter, the temperature is kept constant after time t6 '. When the next step is scheduled after the heat treatment, the temperature may not be lowered as shown in FIG. As described above, various processes may be added after the film forming process from the time t3 to the time t5, but this does not affect the essence of the present invention.

Next, FIG. 9 shows an example in which the pre-process of the film forming process is changed. The set temperature profile shown in FIG.
FIG. 8 shows that a heating step from time t3 '' to t4 '' was inserted after the first stabilization step from time t2 '' to t3 '' and a first stabilization step from time t2 '' to t2 ''. This is different from the set temperature profile. As a result, the film forming step passes the set temperature T2 '' in the first stabilizing step at a time t5 '' in the middle of the step.

As described above, it is also possible to change the process before the film forming process. However, when the previous process is changed, the average center temperature and the average peripheral temperature during film formation change, and the film thickness distribution in the surface of the wafer W may deteriorate. At this time, the set temperature profile is optimized as needed. This optimization may be performed by using the estimated values of the center temperature Tc and the peripheral edge temperature Te, or by modifying the set temperature profile based on the film thickness distribution in the wafer surface after the heat treatment.

The set temperature of the second stabilization step after time t7 '' is also T2 '' as in the first stabilization step. As described above, it is possible to make the set temperature uniform before and after the film forming process.

Until now, only the gradient of the time change set temperature during film formation was negative, but the present invention can be implemented even if the gradient is positive. An example is shown in FIG. 10A shows the set temperature Tsp, the center temperature Tc of the wafer W, and the peripheral temperature Te, and FIG. 10B shows the temperature difference ΔT.
It is a graph which expressed (= Tc-Te) corresponding to time, respectively.

(1) In this embodiment, the temperature is constant at T3 ⁽³⁾ from time t0 ⁽³⁾ to t1 ⁽³⁾ . This temperature T3 ⁽³⁾ is higher than the temperature in the film forming step (high temperature step). At this time, the central temperature Tc and the peripheral edge temperature Te of the wafer W are assumed to be T3 ⁽³⁾ similarly to the set temperature Tsp.

(2) Thereafter, from time t1 ⁽³⁾ to t2
^{To (3)} , the set temperature decreases from T3 ⁽³⁾ to T1 ⁽³⁾ (temperature lowering step). At this time, as described above, the peripheral temperature Te decreases earlier than the central temperature Tc due to heat radiation from the peripheral edge of the wafer W. as a result,
The central temperature becomes a central high temperature state higher than the peripheral temperature, and the temperature difference ΔT (= Tc−Te) becomes positive.

^{(3) The} set temperature Tsp is kept constant from time t2 ⁽³⁾ to t3 ⁽³⁾ (stabilization step). At this time, the temperature difference ΔT gradually approaches zero. And the temperature difference Δ
The process proceeds to the film forming process before T approaches zero. That is, this stabilization step may not be necessary in some cases.

(4) From time t3 ⁽³⁾ to time t5 ^(3), the set temperature Tsp gradually increases from T1 ⁽³⁾ to T2 ⁽³⁾ and the processing gas such as oxygen gas is supplied to the vertical heat treatment furnace 1.
0, and a film is formed (film forming step). At this time, since the wafer W is heated from the peripheral edge, the peripheral temperature Te
Rises faster than the central temperature. As a result, time t
In 4 (4), the wafer W shifts from the central high temperature state to the peripheral high temperature state, and the temperature difference ΔT becomes negative.

As described above, during the film forming process, there are two states of the central high temperature state and the peripheral high temperature state. For this reason, the integral value of the temperature difference ΔT during the film formation approaches 0 as a result of the central high-temperature state and the peripheral high-temperature state canceling each other. This is, as shown in equation (14), the average central temperature Tc during film formation.
(Av) and the mean peripheral temperature Te (Av) approach. As a result, it is expected that the film thickness distribution in the plane of the wafer W approaches uniform.

(5) The temperature lowering step from time t5 ⁽³⁾ to t6 ⁽³⁾ and the unloading step after time t6 ⁽³⁾ are essentially the same as those in FIG. .

As described above, the present invention can be implemented even when the time change set temperature during film formation has a positive gradient. This is suitable when a high-temperature step is performed as a pre-treatment and then a heat treatment is performed.

(Other Embodiments) The above embodiments of the 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,
For example, a glass substrate may be used.

The heat treatment apparatus is not limited to a vertical heat treatment furnace or a batch furnace, but may be a single-wafer heat treatment apparatus for performing heat treatment one by one. However, depending on the arrangement of the substrate and the heater, the order of the gradient of the time-change set temperature and the frequency of appearance of the peripheral high-temperature state and the central high-temperature state may be different. Table 2 shows this relationship.

[Table 2]

As described above, in the vertical heat treatment furnace (an example of a batch type heat treatment furnace), as shown in FIGS. 6 and 10, if the gradient of the time change set temperature is negative (FIG. 6), The wafer W appears in the order of the peripheral high temperature state to the central high temperature state, and if the time change set temperature gradient is positive (FIG. 10),
The wafer W appears in the order from the central high temperature state to the peripheral high temperature state.

Since the vertical type heat treatment furnace performs the heat treatment in a state where the wafers W are stacked, heating and heat radiation are performed from the periphery of the wafer W (peripheral heating method). It is due to change.

On the other hand, in the single wafer method, since the heat treatment is performed for each wafer W, heat and heat are radiated from the surface of the wafer W, that is, near the center (central heating method). As a result, the central temperature tends to change prior to the peripheral temperature, and the order of appearance of the high-temperature state (the central high-temperature state, the peripheral high-temperature state) is opposite to that of the peripheral heating method. As described above, the present invention can be implemented regardless of a batch type or a single-wafer type.

In the present invention, the gradient of the time-change set temperature may be properly used depending on whether the pre-step before the stabilization step is the heating step or the cooling step. This is shown in Table 3.

[Table 3] That is, if the preceding step is a temperature raising step, the gradient of the time change set temperature may be negative (FIG. 6), and if the preceding step is a temperature decreasing step, the gradient of the time change set temperature may be positive (FIG. 10). This relationship can be applied regardless of whether the heating method is the peripheral heating method or the center heating method.

It goes without saying that a very short pre-process in which the influence on the temperature distribution of the substrate is small can be ignored.

The gradient of the set time change temperature is not necessarily required to be constant. In short, the present invention only requires the appearance of two states, a central high-temperature state and a peripheral high-temperature state, during film formation. The gradient of the time-change set temperature changes, and in some cases, the sign of the gradient changes during film formation. No problem.

The two states of the central high-temperature state and the peripheral high-temperature state are not limited to two, and three or more high-temperature states such as the central high-temperature state, the peripheral high-temperature state, and the central high-temperature state may be passed. .

The purpose of the heat treatment is diffusion, annealing, formation of a thermal oxide film, and CVD (Chemical Vapor Depth).
film (for example, film formation of SiN or the like). That is, the present invention can be applied to any process in which the temperature distribution in the substrate poses a problem.

The heaters need not be divided,
The number of sections is not limited to five. In addition, the heater temperature is always controlled from the central temperature Tc and the peripheral temperature Te to the representative temperature Tr.
It is not something that must be calculated and performed.
A temperature representative of the substrate in some form can be used as appropriate.

The center temperature Tc and the peripheral edge temperature Te may be directly measured instead of being estimated from the measurement signals of the temperature sensors Sin and Sout. For this measurement, for example, (a) a temperature sensor such as a thermocouple is connected to the monitor wafers W1 to W1.
It is possible to use a method of installing the sensor at W5 or (b) non-contact measurement using a radiation thermometer or the like. At this time, the temperature sensors Sin and Sout may be removed.

[0089]

As described above, in the present invention, during the heat treatment step, both the central high-temperature state where the vicinity of the substrate is high and the peripheral high-temperature state where the vicinity of the substrate periphery is high are both taken. By canceling out both the central high-temperature state and the peripheral high-temperature state,
If averaged over time, the central temperature and the peripheral temperature are closer. As a result, even if the stabilization time is shortened, it is easy to ensure the uniformity of the heat treatment on the substrate surface.

[Brief description of the drawings]

FIG. 1 is a 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 block diagram illustrating details of a control unit of the vertical heat treatment apparatus according to the present invention.

FIG. 4 is a graph showing an example of a set temperature profile of the vertical heat treatment apparatus according to the present invention.

FIG. 5 is a flowchart showing a control procedure of the vertical heat treatment apparatus according to the present invention.

FIG. 6 shows the wafer temperature and the temperature when the vertical heat treatment apparatus is controlled according to the set temperature profile according to the present invention.
4 is a graph showing a temperature change in a wafer surface and a temporal change of a heater output.

FIG. 7 is a graph showing a change over time in a wafer temperature and a wafer surface temperature difference when a vertical heat treatment apparatus is controlled according to a set temperature profile as a comparative example of the present invention.

FIG. 8 is a graph showing an example of a modification of the set temperature profile of the vertical heat treatment apparatus according to the present invention.

FIG. 9 is a graph showing an example of a modification of the set temperature profile of the vertical heat treatment apparatus according to the present invention.

FIG. 10 is a graph showing an example of a modification of the set temperature profile of the vertical heat treatment apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vertical heat treatment furnace 20 Wafer boat 21 Top plate 22 Bottom plate 23 Prop 30 Boat elevator 40 Reaction tube 40a Outer tube 40b Inner tube 41 Gas hole 50, 51-55 Heater 60 Gas supply tube 65 Flow controller 70 Exhaust tube 75 Displacement volume Controller 80 Opening 81 Lid 82 Heat insulation cylinder 91 to 95 Power controller 100 Control unit 110 Substrate temperature estimation unit 120 Representative temperature calculation unit 130 Set temperature profile storage unit 140 Heater output determination unit

 ──────────────────────────────────────────────────続 き Continued 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. 3rd-6th Tokyo Electron Co., Ltd. F term (reference) 4K029 AA24 DA04 DA08 EA03 EA08 4K030 EA03 HA13 HA17 JA09 JA10 KA24 5F045 AA06 AA20 AB32 AC11 BB02 DP19 EK22 EK27 EK30 GB01 GB05

Claims (19)

[Claims] 1. A heat treatment apparatus for performing heat treatment by disposing a substrate in a processing chamber, comprising: a heating unit for heating the substrate; and a processing gas for forming a film on the substrate in the processing chamber. Introducing a gas introduction unit, including a set temperature profile representing the relationship between the passage of time and the set temperature, and according to a processing recipe having at least a heat treatment step description unit that describes a heat treatment step of forming a film on the substrate. A control unit that controls the heating unit and the gas introduction unit, wherein during the heat treatment step, the central temperature near the center of the substrate is higher than the peripheral temperature near the peripheral edge, and the peripheral temperature of the substrate is higher. The heat treatment apparatus according to claim 1, wherein the set temperature profile is defined so that a peripheral high temperature state higher than the central temperature appears. 2. The set temperature profile is defined such that a time average value of the central temperature of the substrate during the heat treatment step is substantially equal to a time average value of the peripheral edge temperature. The heat treatment apparatus according to claim 1. 3. The heat treatment according to claim 1, wherein the set temperature profile is defined such that the set temperature during the heat treatment step is a time-change set temperature that changes with time. apparatus. 4. The heat treatment apparatus according to claim 3, wherein the set temperature profile is defined such that the set temperature prior to the heat treatment step is the time change set temperature. 5. A method for performing a heat treatment of a substrate by controlling a temperature according to a set temperature, comprising: a heat treatment step of forming a film on the substrate in a treatment gas atmosphere; A heat treatment method for a substrate, comprising: a central high-temperature step in which a central temperature near a center is higher than a peripheral temperature near a peripheral edge; and a peripheral high-temperature step in which the peripheral temperature of the substrate is higher than the central temperature. 6. The heat treatment method according to claim 5, wherein the set temperature in the heat treatment step is a time-change set temperature that changes with time. 7. The heat treatment method according to claim 6, wherein the time change set temperature in the heat treatment step decreases with time. 8. The heat treatment method according to claim 7, wherein the central high-temperature step is performed after the peripheral high-temperature step. 9. The heat treatment method according to claim 6, wherein the temperature change set temperature in the heat treatment step increases with time. 10. The heat treatment method according to claim 9, wherein the peripheral high-temperature step is performed after the central high-temperature step. 11. The heat treatment method according to claim 5, wherein a time average value of the central temperature of the substrate in the heat treatment step is substantially equal to a time average value of the peripheral temperature. 12. The heat treatment method according to claim 5, wherein the peripheral temperature is an average value of temperatures at a plurality of locations near the peripheral edge. 13. The method according to claim 5, wherein in the heat treatment step, the concentration of the processing gas is substantially constant over time.
The heat treatment method described. 14. The method according to claim 1, wherein in the heat treatment step, the pressure of the processing gas is substantially constant over time.
3. The heat treatment method according to 3. 15. The heat treatment method according to claim 5, further comprising, before the heat treatment step, a temperature increasing step in which a set temperature increases with time. 16. The method according to claim 15, further comprising a time-varying set temperature step in which the set temperature changes with time between the temperature raising step and the heat treatment step.
The heat treatment method described. 17. The heat treatment method according to claim 15, further comprising a steady set temperature step in which a set temperature is substantially constant between the temperature raising step and the heat treatment step. 18. A method of heat treating a substrate, the method comprising: heating a substrate with a heat output in a first range to increase a central temperature near a center of the substrate and a peripheral temperature near a peripheral edge of the substrate. Heating the substrate from the periphery of the substrate with a heat output in a second range smaller than the heat output in the first range in a process gas atmosphere, thereby lowering the center temperature and the periphery temperature. A heat treatment step of forming a film on the substrate,
And a heat treatment step including a central high temperature step in which the central temperature of the substrate is higher than the peripheral temperature and a peripheral high temperature step in which the peripheral temperature is higher than the central temperature. 19. A recording medium recording a processing recipe for controlling a heat treatment apparatus for performing a heat treatment on a substrate, wherein the processing recipe includes a set temperature profile representing a relationship between a lapse of time and a set temperature. And at least a heat treatment process description portion that describes a heat treatment process of forming a film on the substrate, wherein a central high temperature near the center of the substrate is higher than a peripheral temperature near the periphery during the heat treatment. A recording medium recording a processing recipe, wherein the set temperature profile is defined so that a peripheral high temperature state in which the peripheral temperature of the substrate is higher than the central temperature appears.