JPH06177141A - Heat treatment furnace - Google Patents

Abstract

PURPOSE:To enhance uniformity of temperature on the surface of a wafer by bringing the temperature of a wafer close to a set value while taking account of the fact that the distance between a wafer supported at three points and a heating stage and the fluctuation thereof have significant effect on the wafer temperature and the uniformity of temperature on the surface. CONSTITUTION:The heat treatment furnace comprises a supporting means 20 for adjusting the heights of three supporting points 13a of a wafer 11 individually (e.g. a piezoelectric unit 17 exhibiting reverse piezoelectric effect interposed between a supporting pin 13 and the base), means for detecting distance between the wafer 11 and a heating stage 12 or means for detecting temperature distribution on the main surface of the wafer 11, and a controller 19 receiving a distance or temperature detection signal and feeding a control signal for adjusting the height of the supporting point 13a back to the supporting means 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus, and more particularly to a heat treatment apparatus for single wafer type baking and annealing of semiconductor wafers.

[0002]

2. Description of the Related Art Among single-wafer heat treatments for semiconductor wafers,
For example, in the baking performed after applying a photoresist to a wafer and the heat treatment performed for baking the developed photoresist pattern, a method of bringing a semiconductor wafer into close contact with a heating stage is generally adopted.

However, in recent years, in order to prevent backside contamination of the semiconductor wafer, as shown in FIGS. 7 and 8, the semiconductor wafer 1 is held by a holding pin 3 or the like having a small contact area, and the heating stage 2 is held. On the other hand, attempts have been made to heat-treat the semiconductor wafer 1 in a non-contact manner (hereinafter referred to as non-contact bake). 7 and 8, reference numeral 4 is a heat insulating material, 5 is a support, and 6 is a base (base).

The aforementioned photolithography (photo-etching, phot
In the heat treatment of photoresist in the (o-lithography) process, the temperature of the wafer is, for example, about several tens of degrees (° C.) for solvent drying after resist application and about one hundred and several tens of degrees for baking the resist pattern after development. It is set and the variation is required to be ± 0.

However, in such a non-contact bake, the uniformity of the temperature of the wafer and the in-plane temperature of the wafer are
It is greatly influenced by the distance between the heating stage 2 and the wafer 1 and the variation in the distance within the wafer surface. Figure 7
In the conventional example, the distance between the wafer 1 and the heating stage 2 is several hundred μm, and the rate of temperature change due to the distance is 1 ° C.
It is about 10 μm. The set temperature of the wafer and its variation are influenced by the temperature distribution on the surface of the heating stage and the air flow around the wafer, in addition to the above distance.

[0006]

In the heat treatment such as single-wafer non-contact baking and non-contact annealing of semiconductor wafers, the heat treatment temperature of the wafer to be processed and the uniformity of the temperature within the wafer are the characteristics of the device and the characteristics of the device. Greatly affect the dispersion of. However, in the conventional technology, the uniformity of the temperature of the wafer and the temperature within the wafer surface is greatly affected by the distance between the wafer to be processed and the heating source and the variation in this distance within the wafer surface, and a satisfactory result is obtained. There was a problem that I could not get it. This problem becomes more prominent with the increase in wafer diameter (125 to 200 mmφ).

The present invention has been made in view of the above problems, and in a single-wafer heat treatment apparatus for performing heat treatment such as non-contact baking and non-contact annealing on a semiconductor wafer, the temperature of the semiconductor wafer is brought close to a set value, and It is intended to improve the uniformity of in-plane temperature of a semiconductor wafer.

[0008]

A heat treatment apparatus according to claim 1 of the present invention comprises a heating stage which faces a semiconductor wafer main surface and heats the wafer in a non-contact manner, and three supporting wafers or heating stages. Supporting means for supporting at each point and independently adjusting the height of each supporting point, means for detecting the distance between the wafer and the heating stage facing each other, or detecting the temperature distribution on the main surface of the wafer Means, or two means for detecting the distance and temperature distribution, and a controller for receiving a detection signal from the detection means and for sending a control signal for adjusting the height of the support point to the support means. It is a feature.

Further, the heat treatment apparatus according to claim 2 of the present invention comprises means for heating the wafer by irradiating the main surface of the semiconductor wafer with electromagnetic waves (including light) from a lamp or a microwave electron tube, and three wafers. Supporting means for supporting the supporting points and independently adjusting the height of each supporting point, and means for detecting the temperature distribution of the wafer main surface,
A controller for receiving a detection signal from the detecting means and sending a control signal for adjusting the height of the supporting point to the supporting means.

[0010]

The heat treatment apparatus according to the present invention is an apparatus for heat-treating a semiconductor wafer at a position which is in non-contact with and close to the heating stage. The temperature of the wafer and the temperature variation are mainly due to the difference between the wafer and the heating stage. Is determined by the distance and the variation of the distance.

The distance between the wafer and the heating stage is adjusted by fixing the height of one of the wafer and the heating stage and raising or lowering the height of the other. For example, if the height of the heating stage is fixed,
The wafer is supported by three support points, and the heights of the three support points can be raised and lowered independently of each other. This ensures that the distance between the main surface of the wafer and the main surface of the heating stage can be made equal over the entire opposing surface. Moreover, even if the temperature of the heating stage main surface is uneven, the wafer main surface is
It can be tilted in any direction and angle, and its effect can be greatly mitigated.

Of the three or more distance sensors for detecting the distance between the wafer and the heating stage and the temperature sensor for detecting the temperature distribution on the main surface of the wafer, distance information or temperature information, or distance and temperature information is input to the controller. To be done.

The controller has a built-in microcomputer and processes the inputted distance or temperature information to bring the average temperature of the wafer close to a set value so that the in-plane temperature of the wafer becomes as uniform as possible. A feedback control signal for adjusting the height is sent to the support means. That is, automatic control is performed.

It is a desirable embodiment to use a piezoelectric element unit as means for adjusting the height of the supporting point.

According to a second aspect of the present invention, there is provided a heat treatment apparatus which uses lamp heating or microwave heating as a heating method, and has means for detecting the temperature distribution on the main surface of the wafer, and detects the distance between the wafer and the heating source. It differs from the heat treatment apparatus according to claim 1 in that the means for performing is not required. The operation of each component is based on claim 1.

As a means for independently adjusting the heights of the three support points according to the second aspect, it is a desirable embodiment that an actuator having a feed mechanism by a stepping motor is provided for each support point. .

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are a schematic sectional view and a plan view showing the outline of the configuration of a first embodiment of a heat treatment apparatus according to claim 1 of the present invention. Semiconductor wafer 11 (caliber 125
The heating stage 12 is provided so as to face the main surface of (about 200 mmφ). The heating stage 12 is a stack of an insulated heater and a heat transfer member, and is surrounded by a heat insulating material 14 to keep its temperature. In this embodiment, the temperature of the exposed surface of the heating stage is several tens of degrees to several hundreds of degrees (° C.), the temperature distribution of the stage surface is made uniform, and the opposing wafer 11 is heated without contact.

The wafer supporting means is composed of three sets of supporting bodies 20 each including a holding pin 13 and a piezoelectric element unit 17 inserted between the holding pin 13 and the base 16.
The wafer 11 is supported by the support points 13a of the three holding pins 13, and the height of each support point can be independently adjusted by the corresponding piezoelectric element unit 17.

As is well known, a piezoelectric element has a property of generating mechanical strain proportional to the electric field applied to the piezoelectric body from the outside (referred to as an inverse piezoelectric effect), and the piezoelectric element unit has such a piezoelectric element. A plurality of elements are laminated in the direction in which the mechanical strain is added, and the length in the strain direction is changed by applying an electric field from the outside. The height of the supporting point is adjusted by utilizing this change in length. In this embodiment,
The distance between the heating stage 12 and the wafer 11 is several hundred μ
m, for example, when the wafer temperature is hundreds of degrees, the distance is 10 μm.
The temperature change rate is about 1 ℃. The adjustment of the height of the support point by the piezoelectric element unit is electric, has a simple structure, and has many advantages.

As the means 18 for detecting the distance between the wafer 11 and the heating stage 12 facing each other, a commercially available capacitance distance sensor 18 was used. The distance sensor may be of another type such as utilizing the interference of light.
In this embodiment, three distance sensors are used and provided near the outer peripheral edge of the radius connecting the center P of the wafer 11 and the support point 13a. The number of distance sensors installed may be three or more, but at least three are required.

The controller 19 has a built-in microcomputer, and the correlation between the distance between the wafer and the heating stage and the wafer temperature distribution is obtained in advance by trial, and this data is stored (recorded) in the computer. The controller 19 receives the distance information from the distance sensor 18, generates a control signal for adjusting the height of the supporting point from the stored correlation data between the distance and temperature, the set temperature of the wafer, and the like, and the piezoelectric element unit. It is fed back to 17, and this is repeated to automatically control.

In the apparatus of the first embodiment, the wafer 11
The distance between the heating stage 12 and the heating stage 12 can be uniformly set within the plane of the wafer 11, and the error between the temperature of the wafer 11 and the set temperature caused by the difference in the distance is small, and the in-plane temperature is small. Uniformity can be improved. Further, in this apparatus, the wafer temperature is indirectly controlled by the distance between the wafer and the heating stage, which is a practical method with a simple structure and control.

FIG. 3 is a schematic sectional view showing the outline of the configuration of the second embodiment of the heat treatment apparatus according to claim 1 of the present invention. The same reference numerals as those in FIGS. 1 and 2 represent the same or corresponding parts.

The second embodiment shown in FIG. 3 is a heat treatment apparatus in which a radiation thermometer 30 is further provided above the wafer 11 in the first embodiment. As the radiation thermometer 30, a commercially available infrared radiation thermometer (one capable of obtaining a temperature distribution image) is used, and it is possible to detect temperatures at desired plural points substantially at the same time.

In the second embodiment, the temperature distribution of the wafer 11 is measured by the radiation thermometer 30, and the temperature information and the distance information of the distance sensor 18 are input to the controller 19, and the preset temperature data input in advance. Etc., the control signal is sent to each of the three piezoelectric element units 17, and the height of each holding pin 13 is controlled.

Here, the temperature information is mainly the wafer 11
Is used to bring the temperature of the wafer 11 close to the set value and improve the in-plane temperature uniformity of the wafer 11. The distance information is used to prevent the wafer 11 and the heating stage 12 from coming into contact with each other when the height of the holding pin 13 is controlled by the temperature information. Compared to the first embodiment, this embodiment can cancel the influence of the gas flow around the wafer 11 and the non-uniformity of the temperature distribution in the heating stage plane, and can reduce the temperature variation in the wafer 11 plane. With characteristics.

As described above, the obtained effect is more accurate in the second embodiment than in the first embodiment, because the object to be controlled is directly controlled. However, the structure and control of the first embodiment are simple and easy to implement.

FIG. 4 is a schematic sectional view showing the outline of the configuration of the third embodiment of the heat treatment apparatus according to claim 1 of the present invention. In this embodiment, the distance sensor provided in the second embodiment is omitted, and the heating stage 12 is supported by the supporting points 25a of the three supports 25 via the heat insulating material 14. Support 2
The piezoelectric element unit 27 can be inserted between the base 5 and the base 16, and the height of the support point 25a can be adjusted independently by the control voltage applied to the piezoelectric element unit 27. The wafer 11 is placed on the holding pins 23 and held at a constant height.

In this embodiment, the radiation thermometer 30 detects the temperature distribution on the wafer 11, and the detected data is sent to the controller 19. From the temperature information data and the reference data stored in advance, the controller 19 sends a control signal for adjusting the height of the support point 25a so that the wafer temperature is set to the set temperature and the temperature variation is reduced. It feeds back to the piezoelectric element 27.

Although the first to third embodiments have described the hot plate type heat treatment apparatus, the above method of controlling the temperature of the wafer by supporting the semiconductor wafer at three points and adjusting the height of the supporting points. Can also be applied to lamp heating and microwave heating of wafers. FIG. 5 is a sectional view showing a fourth embodiment in which the present invention is applied to lamp heating. A lamp (tungsten halogen lamp) 31 and a reflector 32 are provided above the semiconductor wafer 11 to irradiate the main surface of the wafer 11 with light (electromagnetic waves).
To heat. Reference numeral 33 is a power supply device for the lamp 31 (Power su
pply). The heating means is a lamp 31, a reflector 3
2 and a power feeder 33 and the like.

The wafer 11 is supported substantially horizontally by the support points of the three holding pins 13. Further, the heights of the supporting points are independently raised and lowered by the actuators 34 inserted between the holding pins 13 and the base 16, respectively.
The holding position of 1 is adjusted. The actuator 34 is
It is composed of a stepping motor and a feed mechanism such as a ball screw, and drives the motor according to a control signal from the controller 29 to adjust the height of the holding pin 13. An infrared radiation thermometer 30 for detecting the temperature distribution on the main surface of the wafer is provided above the wafer, and the detected temperature distribution information is
It is sent to the controller 29. The controller 29 is
The temperature distribution information from the infrared radiation thermometer 30 is input, the control signals are output to the actuator 34 and the lamp power feeder 33, respectively, and the temperature of the wafer 11 is automatically controlled so that the temperature becomes the set temperature and the temperature distribution becomes uniform. Do. FIG. 6 is a sectional view showing a fifth embodiment in which the present invention is applied to microwave heating. In this embodiment, the means for heating the wafer 11 is composed of the magnetron 44, the antenna 46, the shield plate 47, etc. located above the wafer 11. Reference numeral 45 is packing. Semiconductor wafer 11
Is kept almost horizontal by the three holding pins 13 and heated by the microwave (electromagnetic wave) emitted from the magnetron. Wafer 1 by infrared radiation thermometer 30
The temperature distribution of the main surface of No. 1 is detected through the window 28. The controller 39 inputs the temperature distribution information from the infrared radiation thermometer 30 and connects the actuator 2 to the holding pin 13.
The control signal for moving 3 and the control signal for adjusting the microwave output of the magnetron 33 are output respectively,
Automatic control is performed so that the temperature of 1 becomes the set temperature and the temperature distribution becomes uniform.

[0033]

As described above, in the single-wafer heat treatment apparatus of the present invention for baking or annealing a semiconductor wafer in contact with the semiconductor wafer, the temperature of the semiconductor wafer is brought close to the set value and It was possible to improve the uniformity of the in-plane temperature.

[Brief description of drawings]

FIG. 1 is a sectional view showing the configuration of a first embodiment of a heat treatment apparatus of the present invention.

FIG. 2 is a plan view showing an outline of the heat treatment apparatus shown in FIG.

FIG. 3 is a sectional view showing the configuration of a second embodiment of the heat treatment apparatus of the present invention.

FIG. 4 is a sectional view showing the configuration of a third embodiment of the heat treatment apparatus of the present invention.

FIG. 5 is a sectional view showing the configuration of a fourth embodiment of the heat treatment apparatus of the present invention.

FIG. 6 is a sectional view showing the configuration of a fifth embodiment of the heat treatment apparatus of the present invention.

FIG. 7 is a cross-sectional view showing an example of the configuration of a conventional heat treatment apparatus.

8 is a plan view showing an outline of the heat treatment apparatus shown in FIG.

[Explanation of symbols]

 1, 11 Semiconductor wafer 2, 12 Heating stage 3.13.23 Holding pin 4,14 Heat insulating material 5.15.25 Support 6,16 Base substrate 13a, 25a Support point 17,27 Piezoelectric element unit 18 Distance sensor 19,29 , 39 controller 20 supporting means 30 radiation thermometer 31 lamp 32 reflector 33 power feeder 34 actuator 44 magnetron 46 antenna 47 shield plate

Claims (2)

[Claims] 1. A heating stage which faces a semiconductor wafer main surface and heats the wafer in a non-contact manner, and the wafer or the heating stage is supported by three supporting points, and the height of each supporting point is independently adjusted. Support means capable of, at least one of the means for detecting the distance between the facing wafer and the heating stage and means for detecting the temperature distribution of the main surface of the wafer, and the detection means A heat treatment apparatus comprising: a controller that receives a detection signal and sends a control signal for adjusting the height of a support point to the support means. 2. A means for irradiating an electromagnetic wave on a main surface of a semiconductor wafer with a lamp or a microwave electron tube to heat the wafer, the wafer is supported by three supporting points, and the height of each supporting point is independent. Adjustable supporting means, means for detecting the temperature distribution of the wafer main surface, and a controller for receiving a detection signal from the detecting means and sending a control signal for adjusting the height of the supporting point to the supporting means,
A heat treatment apparatus comprising.