JP2002198320A - Heat treatment apparatus and its method, and method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize heat treatment with high accuracy by selecting a PID parameter applicable to substrate structure and making temperature profile of a heat treatment proper for control by a closed circuit. SOLUTION: A heat treatment apparatus 11 provides a control of the closed circuit for controlling temperatures of heating sources 31, 32, and is equipped with a control system 45 for judging the kind of a substrate 51 by a time required till the substrate 51 reaches a predetermined temperature when the substrate 51 is heated in a chamber 21 of the heat treatment apparatus 11 before performing control by the closed circuit.

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, and a method for manufacturing a semiconductor device, and more particularly, to a heat treatment apparatus for performing heat treatment on a substrate to be heat-treated in a temperature sequence suitable for the type of the substrate. The present invention relates to a heat treatment method and a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art As devices have been miniaturized, a lamp heating apparatus for performing a heat treatment at a high temperature for a short time has been used in order to reduce a thermal budget. In recent years, the holding temperature time may be 1 second or less as in spike annealing.

[0003] FIG. 3 shows an example of a lamp heating treatment apparatus of a single-wafer heating treatment apparatus. As shown in FIG. 3, the lamp heating apparatus 111 includes a quartz chamber 121, and after loading a wafer 151 into the chamber 121, the heating lamp 1 disposed at the upper and lower parts of the chamber 121.
The structure is such that the wafer 151 is heated by 31 and 132. A pyrometer is mounted below the wafer 151 as a temperature sensor 141. As the temperature sensor 141, a contact-type thermocouple can be used in addition to the pyrometer. The wafer 151 carried into the chamber 121 is supported by a wafer support (not shown).

Further, a PID controller 142 and a lamp controller 143 are provided. The above PI
The D controller 142 controls the lamp controller 143 based on the temperature information measured by the temperature sensor 141.
, The lamp controller 143 controls the heating lamps 131 and 13 based on the heating temperature specified by the PID controller 142.
2 is controlled.

The output of the heating lamps 131 and 132 is generally controlled in a closed circuit by feeding back the temperature measured by a temperature sensor 141 such as a pyrometer or a thermocouple to the heating lamps 131 and 132. The sampling period of the temperature to be fed back is 10 ms to 5
0 ms is common. PID control is often used for control.

[0006] The PID control method is the most general control method among the control methods, and PID is an abbreviation for Proportional (proportional), Integral (integral), and Derivative (differential). In this control, the operation is proportional to the deviation from the target value (in the example of the present invention, the operation is to increase the power of the lamp),
This control includes three operations: an integral operation proportional to the integral of the deviation and a differential operation proportional to the derivative of the deviation. The PID control has three coefficients, which are proportional gain, integration time,
It is called the derivative time. It is said that by optimizing this coefficient, control with a small deviation from the target value can be realized.

[0007] Each coefficient of the PID control is set in advance for each recipe when conditions are set. It depends not only on the recipe (heating rate and temperature reached), but also on the structure of the wafer. This is because the rate of temperature rise is different due to the difference in the amount of lamp light absorption depending on the wafer structure.

[0008]

As described above,
The optimum value of each coefficient of the PID control differs not only depending on the recipe (heating rate and reaching temperature), but also depending on the structure of the wafer.

An example is shown in FIG. FIG. 4 shows that the temperature of a wafer having four different structures was raised at a rate of 50 ° C./s.
This shows the overshoot temperature with respect to the emissivity of the back surface of the wafer measured simultaneously in the heat treatment apparatus when the heat treatment was performed at 00 ° C. for 10 s. Is becoming In addition,
The emissivity cannot be measured without increasing the processing temperature. In FIG. 4, the ordinate indicates the overshoot temperature, and the abscissa indicates the emissivity on the back surface of the wafer.

[0010] The overshoot temperature is as small as 1 ° C to 2 ° C for a wafer whose backside emissivity is around 0.76, but the overshoot temperature is 7 for a wafer whose backside emissivity is 0.5 or less.
C. to 8 C. It is considered that the coefficient optimized for the wafer with the backside emissivity of 0.76 cannot cope with the wafer with the low backside emissivity because the absorptance of the lamp light differs depending on the wafer structure. This data is based on the case where the heating rate is 50 ° C./s. However, since the amount of temperature change with respect to the sampling cycle of the temperature monitor becomes large, it is considered that the difference in overshoot temperature becomes larger as the heating rate is increased. In addition, an increase in the amount of overshoot causes deterioration of semiconductor device characteristics.

Incidentally, as shown in the relationship diagram between the heating temperature and the heating time in FIG. 5, in the heating process using the optimized PID parameters (indicated by squares), the temperature change during heating and holding is an allowable value. For example, within ± 2 ° C. On the other hand, in the heat treatment indicated by triangles, crosses, and diamonds, the temperature change during the heating and holding exceeds the allowable value, for example, ± 2 ° C. Note that a substrate in which a silicon oxide film and a 100-nm-thick polysilicon film are laminated on both surfaces of a silicon substrate having a thickness of 720 μm is used, and the temperature profile of a silicon oxide film having a thickness of 50 nm is indicated by a square mark. The temperature profile of a silicon oxide film having a thickness of 20 nm is indicated by a diamond, the temperature profile of a silicon oxide film having a thickness of 100 nm is indicated by a triangle, and the temperature profile of a silicon oxide film having a thickness of 200 nm is shown. Profiles are indicated by crosses.

To solve this problem, it is necessary to perform a wafer process as shown in FIG. As shown in FIG. 6, "preparation for wafer processing" is first performed, and then "whether or not the wafer has a new structure" is determined. In the case of a newly structured wafer,
Adjustment of PID parameters by applying process temperature to wafers having the same structure. " Then, “creation of a recipe having optimized PID parameters” is performed for each wafer structure.
After that, “process processing” is performed based on the created recipe. On the other hand, if the wafer does not have a new structure, “selection of a recipe having optimized PID parameters” is performed. After that, “process processing” is performed based on the selected recipe.

However, in the above-described wafer processing, every time a wafer having a new structure is processed, it is necessary to perform a heat treatment on the wafer having the same structure as the wafer to optimize the PID parameters. Further, when handling wafers of a large variety of small-quantity production, it is necessary to separately create recipes even at the same processing temperature and processing time, and the number of recipes is enormous. As another solution, there is a method of shortening the interval of the sampling cycle of the temperature monitor. However, at present, the system is expensive and difficult to realize.

[0014]

SUMMARY OF THE INVENTION The present invention is directed to a heat treatment apparatus, a heat treatment method, and a method for manufacturing a semiconductor device, which have been made to solve the above-mentioned problems.

The heat treatment apparatus according to the present invention is a heat treatment apparatus having a closed circuit control for controlling a temperature of a heating source, and heats the substrate in a chamber of the heat treatment apparatus before performing the closed circuit control. And a control system for judging the type of the substrate from a required time until the substrate reaches a predetermined temperature.

In the above heat treatment apparatus, the type of the substrate is determined from the time required for the substrate to reach a predetermined temperature when the substrate in the chamber is heated during the open circuit control before the closed circuit control is performed. Since the control system is provided, the type of the substrate is determined and specified based on the difference in the required time. Therefore, closed circuit control in which the temperature rise profile differs depending on the type of substrate can be performed with an appropriate temperature rise profile. Further, since the overshoot temperature during heating and holding in the heat treatment apparatus is reduced, highly accurate heat treatment is realized.

A heat treatment method according to the present invention is a heat treatment method for subjecting a substrate to heat treatment by a closed circuit control for controlling a temperature of a heating source, wherein the heat treatment is performed in a chamber where the substrate is heat treated before the closed circuit control is performed. A step of determining the time required for the substrate to reach a predetermined temperature when the substrate is heated, determining the type of the substrate from the determined required time, and registering the type in advance based on the determined type of the substrate. A heat treatment method including a step of selecting a control parameter that has been used and a step of heat-treating the substrate in a temperature sequence based on the control parameter.

In the above heat treatment method, a time required for the substrate to reach a predetermined temperature when the substrate is heated in a chamber where the substrate is heat-treated before performing the closed circuit control is obtained, and the obtained required time is obtained. Since the step of determining the type of the substrate from the time is provided, the type of the substrate is specified before the closed circuit control is performed. Therefore, closed circuit control suitable for the type of the substrate can be performed, so that the substrate can be appropriately heated. In addition, since the overshoot temperature during heating and holding in the closed circuit control becomes small,
High-precision heat treatment is realized.

A method of manufacturing a semiconductor device according to the present invention is a method of manufacturing a semiconductor device including a heat treatment step of heat-treating a substrate by closed-circuit control for controlling the temperature of a heating source, wherein the semiconductor device is manufactured before the closed-circuit control. Determining the time required for the substrate to reach a predetermined temperature when the substrate is heated in a chamber where the substrate is heat-treated, and determining the type of the substrate from the determined required time; and A method for manufacturing a semiconductor device, comprising: a step of selecting a control parameter registered in advance according to a type of a substrate, and a step of heat-treating the substrate in a temperature sequence based on the control parameter.

In the method of manufacturing a semiconductor device, a time required for the substrate to reach a predetermined temperature when the substrate is heated in a chamber where the substrate is heat-treated is determined before the closed circuit control is performed. Since the method includes the step of determining the type of the substrate from the required time, the type of the substrate is specified before the closed circuit control is performed. Therefore, closed circuit control suitable for the type of the substrate can be performed, so that the substrate can be appropriately heated. In addition, since the overshoot temperature during heating and holding in the closed circuit control is reduced, a highly accurate heat treatment is realized.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One example of an embodiment of a heat treatment apparatus according to the present invention will be described with reference to the schematic configuration diagram of FIG.

As shown in FIG. 1, the lamp heating device 11
A chamber 21 made of quartz is provided, and a substrate (eg, a wafer) 51 is loaded into the chamber 21, and then the substrate 51 is heated by heating lamps serving as heating sources 31 and 32 disposed above and below the chamber 21. It has a structure. A pyrometer is mounted as a temperature sensor 41 below the substrate 51. As the temperature sensor 41, a contact-type thermocouple may be used in addition to the pyrometer.
The wafer 51 carried into the chamber 21 is supported by a substrate support (not shown).

The heat treatment apparatus 11 includes a heating source 31,
A PID controller 42 and a lamp controller 43 that perform closed circuit control for controlling the temperature of the lamp 32 are provided. Further, a control system 45 is provided for judging the type of the substrate 51 from the residual heat in the chamber 21 before performing the closed circuit control, that is, from the temperature rising tendency in the open circuit control. Further, the PID controller 42 is connected to the control system 45.
A control parameter, that is, a PID parameter which is registered in advance according to the type of the substrate 51 determined in the above step, is selected, a recipe is created based on the selected parameter, and a temperature sequence is determined by the lamp controller 43 based on the recipe. , 32. Therefore, the heating sources 31 and 32 heat the substrate 51 in a temperature sequence suitable for the substrate structure.

Generally, the temperature range that can be measured by a temperature sensor used in a lamp heating apparatus is 300 ° C. or more. Therefore, the heating sequence is not closed circuit control from the start of heating. That is, open circuit control is performed up to a temperature at which the temperature can be measured. For example, if the temperature sensor is capable of measuring a temperature of 300 ° C. or more and the start temperature of the closed circuit control is 350 ° C., a certain output is supplied to the heating source up to 350 ° C. to heat the substrate. Become. The outline of the contents of the recipe is as follows: (1) purging after loading a wafer; (2) heating by open circuit control (from room temperature to 350 ° C.); (3) heating by closed circuit control (from 350 ° C. to process temperature); 4) There are four stages of cooling (from process temperature to wafer removal temperature).

Here, when the time from when the heating sources 31 and 32 start supplying the output (lamp light) to when the substrate 51 reaches 350 ° C. (heating time by open circuit control) is measured.
The time varies depending on the difference in the absorptance of the lamp light due to the difference in the substrate structure. In the heat treatment apparatus 11, when the substrate 51 is heated in the chamber 21 at the time of the open circuit control before performing the closed circuit control, the type of the substrate 51 is determined based on a time required for the substrate 51 to reach a predetermined temperature. Since the control system 45 for determining the (structure) is provided, the type (structure) of the substrate 51 is determined and specified based on the difference in the required time. For example, in the case where the substrate 51 is formed by laminating a silicon oxide film having a predetermined thickness and a polysilicon film having a predetermined thickness on both sides of a silicon substrate having a thickness of 0.72 μm, it is necessary to grasp in advance. The film structures formed on both sides of the silicon substrate can be specified by comparing the time required to reach a predetermined temperature corresponding to the various film structures. As a result, the heating sources 31 and 32
The absorptance of the lamp light emitted from the lamp.

After the type of the substrate 51 is determined, when the heating process is performed by a closed circuit control at, for example, 350 ° C. or more, the PID is set as a control parameter corresponding to the lamp light absorptance corresponding to the obtained substrate 51. The parameters are loaded into the recipe for the heat treatment and the program is such that closed circuit control can be started. As a result, the PID parameters optimal for the substrate 51 are automatically created on the heat treatment apparatus 11 side, and the substrate 5 is determined based on the PID parameters.
1 is performed. Therefore, the closed circuit control of the heat treatment, which differs depending on the type of the substrate, can be performed with an optimal temperature profile. In addition, the overshoot temperature during heating and holding in the heat treatment apparatus 11 is reduced. Therefore, high-precision heat treatment is realized. In addition, there is no need to change the recipe to another recipe when heating the substrate, and even when processing a substrate having a new structure, there is no need to determine the heating processing conditions. In addition, the heat treatment of the substrate can be easily and accurately performed.

In the above description, an example of lamp heating has been described. However, even in heater heating, the present invention is applicable because infrared absorption is different depending on the wafer structure depending on the wafer structure.

Next, an embodiment of the heat treatment method according to the present invention will be described with reference to the flowchart of FIG. In this heat treatment method, the heat treatment apparatus described with reference to FIG. 1 is used as an example.

As shown in FIG. 2, according to the heat treatment method of the present invention, the structure of the substrate is specified at the time of open circuit control, and the substrate is heat-treated by closed circuit control that controls the temperature of the heating source based on the obtained substrate structure. Heat treatment method.

That is, first, preparation for substrate processing is performed by “preparation for substrate processing”, and subsequently, a recipe for the heat treatment is selected by “selection of recipe”. Next, “process processing” is performed. In this “process processing”, first, the substrate is heated to a predetermined temperature (for example, 350 ° C.) by open circuit control by “heating the substrate by open circuit control”. As a substrate heating source, for example, lamp heating, heater heating, or the like is used.

Next, the type (eg, structure) of the substrate is determined based on the time required for the substrate to reach a predetermined temperature in “determination of type of substrate”. That is, after the heating source also starts to supply an output (lamp light), the substrate is heated to a predetermined temperature (for example, 350
℃) (heating time by open circuit control)
Is measured. Here, the above-described determination is made using the fact that the required time is different depending on the difference in the absorptance of the lamp light due to the difference in the substrate structure. At that time, it is necessary to check in advance the time required to reach a predetermined temperature corresponding to various film structures formed on the substrate. For example, if the substrate is 0.
When a silicon oxide film having a predetermined thickness and a polysilicon film having a predetermined thickness are formed on both sides of a silicon substrate having a thickness of 72 μm, it is possible to cope with various film structures known in advance. By comparing the required time required to reach a predetermined temperature, it is possible to specify the film structure formed on both surfaces of the silicon substrate.

For example, in the case where a silicon oxide film having a predetermined thickness and a polysilicon film having a predetermined thickness are laminated on both sides of a silicon substrate having a thickness of 0.72 μm, it is necessary to grasp in advance. The film structures formed on both surfaces of the silicon substrate can be specified by comparing the time required to reach a predetermined temperature corresponding to the various film structures described above. As a result, the absorptance of the lamp light emitted from the heating source is known.

After determining the type of the substrate, for example,
When shifting to the heating step by the closed-circuit control of 50 ° C. or more, it is registered in advance by “selection of control parameters” corresponding to the type of substrate obtained in “determination of type of substrate” above. A control parameter (here, a PID parameter) is selected. That is, PI as a control parameter corresponding to the absorptance of the lamp light corresponding to the substrate determined above.
The D parameters are loaded into the recipe for the heat treatment, and the program is such that closed circuit control can be started. As a result, an optimal PID parameter for the substrate is automatically created.

Thereafter, "substrate heating processing" is performed by closed circuit control having a temperature sequence based on a recipe based on the control parameters (PID parameters). Therefore, the closed circuit control of the heat treatment, which differs depending on the type of the substrate, can be performed with an optimal temperature profile. In addition, the overshoot temperature during the heating and holding in the closed circuit control is reduced. Therefore, high-precision heat treatment is realized. Moreover, when heating the substrate,
There is no need to replace the recipe with another recipe, and even when processing a substrate with a new structure, there is no need to determine the heat treatment conditions, making substrate heat processing easy and accurate. Will be able to do it.

In the above embodiment, the substrates are selected according to the difference in the absorptance of the lamp light radiated from the heating source, and the optimum PID parameter corresponding to the absorptivity is determined in advance. The heat treatment can be performed with an optimum temperature profile according to the corresponding PID parameter. Therefore, there is no need to change the recipe when heating the wafer. Further, even when processing a wafer having a new structure, it is not necessary to determine conditions, and the wafer can be heated.

Next, an example of an embodiment according to a method of manufacturing a semiconductor device of the present invention will be described below. The heat treatment method described with reference to FIG. 2 can be applied to substrate heat treatment in a semiconductor device manufacturing process. The heat treatment method is the same as the heat treatment method described with reference to FIG. 2, and therefore, the same effect as described above can be obtained.

[0037]

As described above, according to the heat treatment apparatus of the present invention, the substrate reaches a predetermined temperature when the substrate in the chamber is heated during the open circuit control before the closed circuit control is performed. Since a control system is provided for determining the type of the substrate from the required time until, the type of the substrate can be specified based on the difference in the required time. for that reason,
Closed circuit control in which the temperature rise profile differs depending on the type of substrate can be performed with an appropriate temperature profile. Therefore, since the overshoot temperature during heating and holding is reduced, high-precision heat treatment can be realized. Also,
When heating the substrate, there is no need to change the recipe,
Further, even when processing a substrate having a new structure, it is not necessary to determine the conditions, and the efficiency of the heat treatment can be improved.

According to the heat treatment method of the present invention, the time required for the substrate to reach the predetermined temperature when the substrate is heated in the chamber where the substrate is heat-treated before performing the closed circuit control is determined. Since the method includes the step of determining the type of the substrate from the required time, the type of the substrate can be specified before the closed circuit control is performed. Therefore, the closed circuit control of the heat treatment corresponding to the type of the substrate can be appropriately performed, and the overshoot temperature during the heating and holding in the closed circuit control can be reduced, so that a highly accurate heat treatment is realized. Further, there is no need to change the recipe when heating the substrate, and even when processing a substrate having a new structure, it is not necessary to determine the conditions, and the efficiency of the heat treatment can be improved. it can.

According to the method of manufacturing a semiconductor device of the present invention,
Since the same effect as the above-described heat treatment method can be obtained, it is possible to heat and hold at an appropriate temperature. Therefore, the characteristics and reliability of the semiconductor device can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an embodiment according to a heat treatment apparatus of the present invention.

FIG. 2 is a flowchart showing an example of an embodiment according to a heat treatment method of the present invention.

FIG. 3 is a schematic configuration diagram showing a conventional single-wafer lamp heating apparatus.

FIG. 4 is a diagram showing the relationship between the overshoot temperature and the emissivity of the back surface of the wafer.

FIG. 5 is a relationship diagram between a heat treatment temperature and a heating time.

FIG. 6 is a flowchart showing a conventional heat treatment method.

[Explanation of symbols]

11 heat treatment apparatus, 21 chamber, 31, 32 heating source, 45 control system, 51 substrate

Claims (4)

[Claims] 1. A heating processing apparatus having a closed circuit control for controlling a temperature of a heating source, wherein the substrate when the substrate is heated in a chamber of the heating processing apparatus before the closed circuit control is performed. A heat treatment apparatus comprising: a control system that determines a type of the substrate from a time required until the temperature reaches a predetermined temperature. 2. The method according to claim 1, further comprising the step of: selecting a control parameter registered in advance according to the type of the board determined by the control system, and instructing the heating source to perform a temperature sequence based on the control parameter. The heat treatment apparatus according to claim 1, wherein 3. A heat treatment method for subjecting a substrate to heat treatment by a closed circuit control for controlling a temperature of a heating source, wherein the substrate is heated in a chamber where the substrate is heat treated before the closed circuit control is performed. Determining a required time until the substrate reaches a predetermined temperature, determining the type of the substrate from the determined required time, and selecting a control parameter registered in advance based on the determined type of the substrate. And a step of heat-treating the substrate in a temperature sequence based on the control parameter. 4. A method for manufacturing a semiconductor device comprising a heat treatment step of heat-treating a substrate by a closed-circuit control for controlling a temperature of a heating source, wherein the substrate is heat-treated before the closed-circuit control is performed. A step of obtaining a time required for the substrate to reach a predetermined temperature when the substrate is heated in the step of determining the type of the substrate from the obtained required time; and A method of manufacturing a semiconductor device, comprising: a step of selecting a control parameter set forth above; and a step of heat-treating the substrate in a temperature sequence based on the control parameter.