JPH0448724A - Semiconductor heat treatment device - Google Patents

Abstract

PURPOSE:To get a wafer temperature measuring device which can determine real wafer temperature by calculating the emissivity of a semiconductor wafer from the measurment result of the transient change of the radiation energy intensity at the start of the heating of the semiconductor wafer so as to calculate the wafer temperature. CONSTITUTION:Wafer temperature can be measured with a radiation thermometer 11. The radiation thermometer 11 takes in only parallel beams, and further, since it measures the mirror face side of a wafer 1, the lost beam from a lamp, and others do not enter it, either, so it can measure the intensity of the radiation energy from the wafer accurately. To calculate the wafer temperature from the radiation energy intensity, it is desirable to measure the emissivity separately for each wafer, and the larger the emissivity is, the more the wafer absorbs heat and the higher the temperature rise speed is. By measuring the rise speed of the intensity of the radiation energy from the wafer, making use of that phenomena, the emissivity can be sought. If the emissivity is sought, the wafer temperature in heat treatment can be calculated, and the quantity of the heat generated by a lamp can be controlled so that the wafer temperature may be heat treatment temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat treatment apparatus such as an oxidation/diffusion apparatus for semiconductor manufacturing, and particularly to a wafer temperature measuring method and apparatus structure.

[Conventional technology]

As described in Japanese Unexamined Patent Publication No. 131430/1983, the conventional device measures the wafer temperature with an infrared radiation thermometer to control the amount of lamp heating, and also provides a concave reflecting plate on the outside of the lamp. was.

Furthermore, as described in Japanese Patent Application Laid-Open No. 62-128525, a thin annular plate was provided around the wafer to prevent the occurrence of thermal stress defects.

Also, as described in Japanese Patent Application Laid-Open No. 61-67115,
Heat treatment was controlled by arranging rod-shaped lamp groups in two layers orthogonally.

Also, as described in JP-A-64-71118.

Only the lower part of the wafer heated by a flat electric heater was supported by a quartz jig, and the wafer temperature was measured using reflection from a prism.

(Problems to be Solved by the Invention) Japanese Patent Application Laid-Open No. 131430/1982 does not take into consideration the fact that the emissivity changes depending on the surface condition of the wafer, and the indicated value of the radiation thermometer is not the true wafer temperature. In addition, there was a problem that the reflector on the outside of the lamp did not take into consideration the change over time, so it gradually oxidized and the reflection efficiency decreased.

JP-A No. 62-128525 does not take into consideration the fact that the wafer is thermally deformed during heating, and when the wafer is thermally deformed, the position of the wafer and the annular plate is shifted, and the effect of the annular plate is lost. There was a problem with this.

In Japanese Patent Application Laid-open No. 61-67115, it is necessary to form the lamp group into two layers in orthogonal directions, resulting in problems of increased power consumption and increased size of the device.

Japanese Patent Application Laid-open No. 64-71118 has a problem in that in the case of a large diameter wafer, a large force is applied to the lower part of the wafer. Further, there is a problem in that it takes time and effort to adjust the position of the prism when assembling it.

The purpose of the present invention is to determine the emissivity of each wafer to be heat treated,
It is an object of the present invention to provide a wafer temperature measuring device capable of determining the true wafer temperature by correcting the indicated value of a radiation thermometer.

[Means to solve the problem]

In order to achieve the above object, the present invention measures the wafer temperature rise characteristics at the start of wafer heating, calculates the emissivity, corrects the indicated value of the radiation thermometer using the calculated emissivity, and calculates the true wafer temperature. Find the temperature.

[Effect]

For the purpose of the present invention, when a wafer is heated under the same heater heating conditions, the higher the emissivity of the wafer, the higher the rate of temperature rise. Furthermore, the higher the emissivity, the higher the radiant energy intensity. Therefore, the emissivity can be calculated by measuring the rate of increase in the wafer radiant energy intensity at the start of heating. Using this, the true wafer temperature can be determined from the radiant energy intensity.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a longitudinal sectional view of a diffusion device to which the present invention is applied. Rod-shaped heating halogen lamps 2a and 2b are juxtaposed above and below the horizontally supported wafer l. The directions of the upper lamp 2a and the lower lamp 2b are perpendicular to each other. FIG. 2 is a horizontal sectional view showing the lamp array. The wafer 1 is housed in a reaction tube 3 (made of quartz glass, etc.), and a processing gas (nitrogen, atom, etc.) is supplied to the inside of the reaction tube 3. A reflector plate 4 is provided on the outside of the lamps 2a, 2b.

Cooling air flows outside the reaction tube 3 to cool the lamps 2a, 2b and the reflector 4.

A reflecting plate 7 is also provided on the side of the device. The wafer 1 is placed on a support jig 8 (made of quartz glass, etc.), and a cap 9 integrated with the support jig 8 is also provided with a reflective plate 10. A radiation thermometer 11 is provided to measure the temperature of the wafer 1. The radiation thermometer 11 faces the mirror side of the wafer 1. When the mirror side of the wafer 1 is facing upward, the radiation thermometer 11 is provided above the apparatus.

A perspective view of the wafer support jig 8 is shown in FIG.

A band-shaped ring 12 is provided around the wafer. The broken line indicates the position where the wafer is placed, and the strip ring 12
, is at the center position.

A perspective view of the reflection plate 4 is shown in FIG. 4, and as shown in the cross-sectional view of FIG. 14a
, 14b, and an inert gas (nitrogen, etc.) is filled in, and the periphery 14c is hermetically sealed.The zero reflection plates 7 and 10 have a similar structure.

The configuration of the radiation thermometer 11 is shown in FIG. 5, including a lens 15, an aperture 16. Interference filter 171-point hole plate 18° Photo sensor (silicon photo diode, etc.) 19, case 20
By setting the zero point aperture plate 18, which is composed of

Only parallel rays of the incident light are guided to the sensor 19.

The aperture 16 is for adjusting the amount of incident light, and the interference filter 17 is for defining the measurement wavelength.

In this embodiment, the measurement wavelength is 0.6 to 0.9 μm so that the temperature change in the emissivity of silicon is small.

The output of the radiation thermometer 11 is led to a computing unit 21, which calculates the wafer temperature, and transmits a signal to a temperature controller 22 to control the amount of heat generated by the lamp.

The operation and effects of this embodiment will be described below. The support jig 8 is taken out, the wafer 1 is placed thereon, and the support jig 8 is inserted into the apparatus. Due to the heat generated by the lamps 2a and 2b, the wafer 1 reaches a heat treatment temperature (for example, 1000° C.) in about 10 seconds, is heat treated for a predetermined time (for example, 30 seconds), is cooled, and is replaced with the next wafer.

The wafer temperature is measured by a radiation thermometer 11. Since the radiation thermometer 11 inputs only parallel light beams and measures the mirror side of the wafer 1, stray light from the lamp may be input to the radiation thermometer 1.
1, and the intensity of radiant energy from the wafer can be measured with high accuracy. Since the radiant energy intensity from the wafer is proportional to the wafer's emissivity, it is necessary to provide the emissivity in order to calculate the wafer temperature from the radiant energy intensity. Since the emissivity varies depending on the surface condition of the wafer, it is desirable to measure the emissivity for each wafer.The measurement method is as follows. given that,
The rate of temperature rise of the wafer varies depending on the emissivity of the wafer. Figure 7 shows the temperature change of a wafer.A wafer with a high emissivity (broken line in Figure 7) absorbs heat well and has a high rate of temperature rise.Using this phenomenon, we can calculate the rate of increase in the intensity of radiant energy from the wafer. Emissivity can be determined by measurement. At that time, the relationship between emissivity and the rate of increase in radiant energy intensity shall be determined in advance through experiments.

Once the emissivity is determined, the wafer temperature during the heat treatment (after about 10 seconds) can be calculated, and the amount of heat generated by the lamp can be controlled so that the wafer temperature reaches the heat treatment temperature.

The band-shaped ring 12 provided on the wafer support jig 8 is effective in making the temperature distribution within the wafer surface uniform and preventing the occurrence of thermal stress defects. Heating lamp 2a.

2b are located above and below the wafer 1. Therefore, when the wafer 1 reaches a high temperature, heat is radiated toward the sides, causing the peripheral temperature of the wafer 1 to drop below the center temperature.

Since the band-shaped ring 12 blocks heat radiation from the wafer 1 in the side direction, no temperature distribution occurs on the wafer 1.
Although the wafer may be deformed when the wafer temperature rises, since the width of the band-shaped ring 12 is larger than the amount of deformation of the wafer, the wafer 1 does not come off from the band-shaped ring 12.
There is always an effect of the band-shaped ring 12.

Since the reflectors 4, 7, and 10 have a sandwich structure in which a thin plate 13 with a high reflectance is sandwiched between glass plates 14a and 14b with a low coefficient of thermal expansion, each reflector does not undergo thermal deformation and has good reflection efficiency.

Further, since the thin plate 13 is sealed, there is no change over time such as oxidation, and high reflection efficiency can be maintained forever.

Figure 6 shows the relationship between the distance X from the lamp filament and the spatial temperature distribution in which a plurality of rod-shaped lamps are arranged in a plane, and the pitch of the lamps is set to 25.

If the distance X from the lamp is small, the temperature will be high just below the lamp and the temperature will be low between the lamps. If the distance from the lamp is equal to or greater than the pitch (preferably, if the layers are twice the pitch or more), there will be almost no spatial temperature distribution. Therefore, the distance between the wafer 1 and the lamps 2a, 2b is set to be greater than the pitch of the lamps. However, if the distance is more than necessary, the device will become larger, so it is desirable that the pitch be about twice the pitch of the lamps.

In FIG. 6, a description has been given of the rod-shaped lamps, but in the case where the dot-shaped lamps are arranged in a matrix pattern, it is also desirable that the distance between the wafer and the lamps be equal to or greater than the pitch of the lamps.

According to this embodiment, even when heat-treating wafers with various surface conditions, the wafer temperature can be determined with high accuracy using a radiation thermometer, so that the predetermined heat treatment can be performed with high precision without any difference between wafers.

Furthermore, since there is no thermal deformation or aging of the reflector, heat treatment can be performed with high precision for a long time. Furthermore, production efficiency is improved without generating thermal stress defects on the wafer. Further, the entire surface of the wafer can be uniformly heat-treated.

Another embodiment of the present invention will be explained with reference to FIGS. 8 and 9. FIG. 9 is a longitudinal sectional view of a diffusion device to which the present invention is applied, and FIG. 8 is a horizontal sectional view showing the arrangement of lamps and reflectors.

The heating halogen lamps 2 are arranged in parallel in the same direction only below the wafer 1. Six reflecting plates 23 are divided into a plurality of plates, and the direction thereof is perpendicular to the direction of the lamps 2. The distances between the plurality of reflectors 23 and the lamps 2 (that is, the distances 81 from the reflectors 1) can be adjusted individually. Further, a flow path 24 through which a cooling fluid (water, air, etc.) flows is provided at the terminal portion of the lamp 2. The flow direction of the cooling fluid is opposite to the left and right as shown by arrow 25. The rest is the same as the first embodiment.

The operation and effects of this embodiment will be described below. The heating lamp 2 is located only below the wafer 1, and the peripheral temperature of the wafer 1 drops below the center temperature. Therefore, in the parallel direction of the lamps 2, the amount of heat generated by the lamps in the peripheral portion of the plurality of lamps 2 is increased to be greater than the amount of heat generated by the lamp in the center 11. Further, the distance between the reflection plate 23 and the lamp 2 is adjusted in the axial direction of the lamp to control the wafer temperature to be uniform. In other words, if the distance between the reflector plate 23 and the lamp 2 is reduced in one peripheral area, more reflected light will hit the peripheral area of the wafer. It is desirable that the amount of heat generated by each lamp and the position of the reflector be changed depending on the diameter of the wafer, and these can be changed. According to this embodiment, all the lamps are paralleled in the same direction, and only below the wafer, so electrical wiring is easy, the device can be made compact, and power consumption can be reduced. Note that the effect is the same even if the lamp 2 is provided only above the wafer.

The cross-sectional shape of the reflection plate 23 is shown in FIG. It was made into a flat plate with folds 26 on both sides. The folds 26 are used to eliminate gaps between the reflectors when the positions of the reflectors are changed.1 Other embodiments of the shape of the reflectors are shown in Figs.
Convex shape shown in Figure 4.

It is arcuate and concave. Figure 11 or 12
In the case of the convex shape shown in the figure, the reflected light spreads out and has the effect of equalizing the amount of heating to the wafer. In the case of the concave shape shown in FIG. 13 or 14, reflected light gathers and has the effect of locally heating. In the plurality of reflectors 23, if the shape of the reflector at the center of the wafer is convex and the shape of the reflector at the periphery is concave, the effect of making the wafer temperature uniform is large.

Cooling of the lamp terminal portion increases the temperature of the cooling fluid in the flow direction. The temperature of the inner wall of the device also changes with the temperature of the cooling fluid, which causes a temperature distribution on the wafer. By setting the left and right flow directions in opposite directions, the average values of the left and right sides can be approximately matched, so that the temperature distribution of the wafer can be reduced.

According to this embodiment, the device can be downsized and power consumption can be reduced. Further, the amount of heat treatment within the wafer surface can be made uniform.

Another embodiment of the present invention will be described with reference to FIG.

FIG. 15 is a longitudinal sectional view of a diffusion device to which the present invention is applied. A high-temperature space is formed inside by two parallel flat electric heaters 27a to 27i. FIG. 16 is a perspective transparent view showing the arrangement of electric heaters. The device is rectangular. A soaking tube 28 (made of silicon carbide, etc.) and a reaction tube 3 (made of quartz glass, etc.) are provided inside the heater.
There is a heat insulating material 29 around it. The wafer 1 is inserted into the high temperature space by a support jig 8 in an attitude slightly inclined from the vertical direction. The support jig 8 is attached to the upper and lower transport tables 34, and its tip is divided into two parts so that two wafers 1 can be inserted at the same time. A partition plate 30 (made of quartz glass or the like) fixed to the reaction tube 3 is inserted between the two wafers. A perspective view of the tip of the support jig 8 is shown in the 18th article. The longitudinal cross-sectional view of the support jig 8 is shown in FIG.
In the figure, the position where the wafer 1 is placed is indicated by a broken line, and the portion in contact with the wafer 1 has a grooved plate 31 on the lower side and a protrusion 32 on the upper side. The wafer is placed on the grooved plate 3 at a slight angle.
In this embodiment, the inclination angle of the wafer is 5°. A band-shaped ring 12 is provided around the wafer 1 . In order to measure the temperature of the wafer l, one end of the quartz rod 33 faces the wafer l;
The other end is led to a radiation thermometer 11. The radiant energy from the wafer 1 enters the quartz rod 33, and the quartz rod acts like an optical fiber to transmit the radiant energy to the radiation thermometer 11. A cross-sectional view of the quartz rod 33 is shown in FIG. is core 37. Lens 38. In all of the embodiments in which the holder 39 is constructed, the material is quartz glass, and the diameter of the core 37 is 1 mm. The holder 39 has squeezed portions 40 at several places and holds the core 37.

The operation and effects of this embodiment will be described below.The inside of the apparatus is a uniform high temperature space by controlling the heat generation of the plurality of divided heaters 27a to 27i. Two wafers are placed on a support jig 8 below the apparatus, and are inserted into a high temperature space by the action of the upper and lower transport tables 34. The wafer is heat-treated for a predetermined time and then replaced with the next wafer.

Regarding the quartz rod 33, the radiant energy from the wafer 1 is focused by the lens 38 and enters the core 37.

The light is transmitted inside the core 37 by total reflection. The bending radius of the core 37 is at least one time the core diameter. The holder 39 is provided with a mechanism for attaching it to the device (not shown in the figure).1 The quartz rod 33 can be molded to match the shape of the device, and can also be removed from the heater for adjustment. It's easy.

When two low-temperature wafers l are inserted into the heater, the outer surface of the wafer 1 is heated by the heater, and the two wafers 1
Since the inner surface of the wafer 1 is heated by the heat capacity of the partition plate 30 that enters the gap, the temperature of the wafer 1 quickly rises to the heat treatment temperature.

When a wafer is inserted into a high-temperature space, heat transfer to the edges of the wafer causes the peripheral portion to become hotter than the central portion (temperature distribution is opposite to that in the case of lamp heating in the first embodiment). Since the band-shaped ring 12 blocks heating to the edge portion of the wafer, the entire surface of the wafer 1 is kept at a uniform temperature.

Since the wafer 1 is supported in an almost vertical position with point contact above and below, no local force is applied to the wafer even with large diameter wafers, and there is little thermal influence due to jig contact. Therefore, thermal stress defects do not occur on the wafer.

Another embodiment of the support jig will be described with reference to FIGS. 20 to 23. FIG. 20 shows two wafers 1 with opposite inclinations. In this way, when the wafer is placed, it does not get caught on the protrusion 32 and the operation is easy.

FIG. 21 shows a structure in which the support jig 8 is divided into a ring part 41 and a support part 42. In this method, a ring portion 41 on which a wafer is placed is prepared and prepared outside the apparatus, and the ring portion 41 and the wafer are heat-treated as one unit. In this way, the wafer can be placed with the two ring parts 41 separated from each other, and the operation is easy.

In FIGS. 22 and 23, the portion in contact with the wafer 1 is provided by grooved plates 31 at three locations. The wafer 1 is supported in point contact below and on the sides. In this way, the operation when placing a wafer is easy.

FIG. 24 shows the temperature change of the wafer. The higher the emissivity of the wafer (broken line in FIG. 24), the faster the temperature rises. When a wafer is inserted into a high-temperature space created by an electric heater, the wafer temperature eventually reaches the space temperature (when heated for 30 minutes or more), regardless of the emissivity of the wafer. However, when performing heat treatment for a short time of about - minutes or less, the space temperature fluctuates due to the insertion of a low-temperature wafer, so it is necessary to measure the wafer temperature and control the amount of heat generated by the heater. Figure 25 is the 24th
The output of the radiation thermometer shown in the figure corresponds to the wafer temperature, and it can be seen that the higher the wafer's emissivity, the faster the rising speed of the wafer. That is, the emissivity of the wafer can be determined by measuring the rate of increase in the 8 forces of the radiation thermometer when the wafer temperature rises. Once the emissivity is determined, the wafer temperature can be calculated from the output of the radiation thermometer.

According to this embodiment, since heating is performed using an electric heater, power consumption can be reduced compared to lamp heating. Furthermore, the radiation thermometer is easy to assemble and adjust. Further, even with large diameter wafers, thermal stress defects do not occur and production efficiency is improved.

Another embodiment of the present invention will be described with reference to FIG. 26.

FIG. 26 is a perspective sectional view of a diffusion device to which the present invention is applied. A high temperature space is formed inside by a cylindrical electric heater 27. A soaking tube 28 and a reaction tube 3 are provided inside the heater. A large number of wafers 1 are arranged in a boat 43 (made of quartz glass, etc.).

It is inserted into a heater and heat treated. A plurality of quartz rods 33 are attached to a boat 43 for measuring wafer temperature. One end of the quartz rods 33 is facing the wafer 1, and the other end is connected to a connector 35° with a flexible optical fiber 36 connected to a radiation thermometer. It is connected to 11.

Since the wafer temperatures at multiple positions are measured using multiple quartz rods 33, all wafers can be uniformly heat-treated.

〔Effect of the invention〕

According to the present invention, the emissivity is determined for each wafer to be heat-treated and the wafer temperature is measured without contact, so that the wafer can be heat-treated with high precision. In addition, it can prevent thermal deformation and aging of the reflector, preventing deterioration of the characteristics of the device.
Production efficiency improves.

Further, even with large diameter wafers, thermal stress defects do not occur on the wafers, improving production efficiency. Furthermore, the device can be made smaller and power consumption can be reduced.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a diffusion device according to an embodiment of the present invention;
The figure is a horizontal cross-sectional view showing the arrangement of the lamps, Figure 3 is a perspective view of the wafer support jig, Figure 4 is a perspective view of the reflector, Figure 5 is a cross-sectional view of the radiation thermometer, and Figure 6 is a view from the lamp. 7 is a wafer temperature change diagram, FIGS. 8 and 9 are horizontal and vertical sectional views showing other embodiments of the present invention, and FIGS. 10 to 14 are 15 is a longitudinal sectional view showing another embodiment of the present invention, FIG. 16 is a perspective view showing the heater arrangement, and FIG. 17 is a sectional view of the quartz rod.
Figures 8 to 23 are perspective views and cross-sectional views of the wafer insertion jig, Figure 24 is an explanatory diagram showing wafer temperature changes, Figure 25 is an explanatory diagram showing the output of a radiation thermometer, and Figure 26 is an illustration of the present invention. It is a longitudinal cross-sectional view which shows another Example. 1... Wafer, 2, 27... Heater, 4, 7, 10
゜23...Reflector plate, 8...Support jig, 11...Radiation thermometer, 12...Striped ring, 13...Thin plate, 1
4...Glass plate, 24...Cooling fluid flow path, 30.
...Partition plate, 31...Grooved plate, 32...Protrusion, 33
...Quartz rod.

Claims (1)

[Claims] 1. An apparatus for heat-treating a semiconductor wafer by inserting it into a heating space formed by a heat source such as a lamp or a heater, which has a wafer temperature measurement system that measures the intensity of radiant energy from the semiconductor wafer and calculates the wafer temperature. . A semiconductor heat treatment apparatus, characterized in that the emissivity of the semiconductor wafer is calculated from the measurement result of a transient change in radiant energy intensity at the start of heating of the semiconductor wafer, and the wafer temperature is calculated.