JPH02303024A - Semiconductor heat treatment equipment - Google Patents

Abstract

PURPOSE:To improve a wafer temperature measurement accuracy by a method wherein an angle adjusting means is provided, the angle of a radiation thermometer or a semiconductor wafer is adjusted and the generation of an error due to stray light is minimized. CONSTITUTION:An observation window 6 is provided in a part, which opposes to a wafer 3, of the outer periphery of a reaction tube 2 and the temperature of the wafer 3 is measured by a radiation thermometer 7 through the window 6. At this time, unless the wafer 3 is placed on a heat-resistant jig 5 at a right angle to a measuring optical path of the thermometer 7, a probe beam reflected light 15 does not return to a reflected light detecting part 16. The part 16 always measures the angle of the wafer 3 to the measuring optical path of the thermometer 7 and by the measurement result, the flow rate of inert gas, which is made to jet through nozzles 5a formed in the jig 5 which is an angle adjusting means, is changed. Whereupon, the angle of the wafer 3 is controlled so as to be always located in a prescribed position, and an error from stray light, which is caused by heat radiation, is minimized and a wafer temperature measurement accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor heat treatment device such as a diffusion device or an annealing device for heat-treating a semiconductor wafer, and in particular to a radiation fi11 that can accurately measure the humidity of a wafer. The present invention relates to a semiconductor heat treatment equipment that includes a full temperature equipment.

[Conventional technology]

In semiconductor wafer heat treatment equipment such as diffusion equipment and annealing equipment, due to the need for microfabrication due to the high integration of LSI,
It is desired to shorten the heat treatment time and further equalize the wafer humidity. In order to meet this demand, conventionally the temperature inside the processing chamber of heat processing equipment was measured using a thermocouple to ensure uniform processing temperature, but instead of using a radiation thermometer to directly measure the wafer temperature. Devices that perform temperature control using the same technology are becoming mainstream.

However, these heat treatment apparatuses use infrared lamps or electric heaters as heating sources to heat the wafers placed in the furnace, so when measuring the surface temperature of the wafer by radiation, the radiation from the infrared lamps or the furnace wall is After the thermal radiation is reflected by the wafer, it is detected by the radiation thermometer and so-called stray light is generated, resulting in a+! There was a problem in that an error in l temperature occurred. In order to eliminate the occurrence of this stray light, methods such as measuring outside the stray light wavelength band, measuring and correcting the stray light, and using a shielding plate are used.For example, in a lamp annealing device, Since the main wavelength of infrared rays emitted from commonly used heating lamps is 1 μm to 3 μm, the measurement wavelength of the radiation hygrometer is set to 4 μm to 5 μm.
l! l? Correct the output of the radiation thermometer by performing lI& or by measuring the temperature or brightness of the furnace wall that emits stray light. Note that this method is not preferable because the use of a shielding plate makes the temperature of the wafer non-uniform.

It is also effective to provide an opening by removing the infrared lamp or furnace wall located in the optical path of the infrared rays that are reflected from the surface to be measured of the wafer and enter the radiation thermometer.

At this time, since the ambient temperature is generally much lower than the temperature inside the furnace, stray light due to infrared rays emitted from these can be ignored. In this case, in order to measure the diffuse reflection 11, thermal radiation from all hemisphere directions on which the surface to be measured is reflected is reflected by the surface to be measured and emitted toward the radiation thermometer.
Therefore, as shown in FIG. 6, it is necessary to enlarge the opening in the furnace wall 22, bring the object to be measured 23 closer to the opening, and fully open the 21IIII structure for measurement.

However, when the object to be measured 23 is a semiconductor wafer,
Since the surface is very smooth and a specular reflection surface 23b is formed, the thermal radiation 24 is almost specularly reflected. Therefore, it is only necessary to remove the heater 1, such as an infrared lamp, and the furnace M22, which are mirror-symmetrical to the radiation thermometer 7 with respect to the surface to be measured, and provide a small opening.

An example is shown in FIG. 7. In this example, the specular reflection surface 23b of the wafer 23, which is the object to be measured, is perpendicular to the measurement optical path of the radiation thermometer 7.
2a also serves as an opening provided to prevent straying. Reference numeral 23a shown in FIG. 6 is a diffuse reflection surface formed on the measurement surface of the object to be measured 23, and reference numeral 2b in FIG. 7 is stray light.

[Problem to be solved by the invention]

In semiconductor heat processing equipment, in order to make the wafer temperature JW uniform and prevent contamination factors from entering from outside the equipment, it is necessary to avoid as much as possible the structure in which the wafer is exposed to the outside of the heat processing chamber. The opening provided in mirror symmetry with the radiation thermometer must also be made as small as possible.On the other hand, since the surface of a semiconductor wafer is a smooth mirror surface, it is basically impossible to The viewing window or aperture formed in the wall only needs to be slightly larger than the 8-bound optical path of the radiation thermometer; however, measuring the temperature of the wafer through such a small viewing window or opening will prevent the wafer from reaching a predetermined temperature. Even if it is tilted by a small angle from the position,
Once radiation flood occurs, a heat radiation source such as the furnace wall enters the mirror-symmetrical position of the liver, causing errors due to stray light.

For example, in the apparatus shown in FIG. 8, if the wafer 3 deviates from a predetermined angle, the error due to stray light will be as shown in FIG. 9. Here, the furnace wall 22 is heated using a resistance heater l.
Assuming that the wafer 3 placed therein was to be heated, the temperature inside the furnace wall was 1000° C. and the emissivity was 1. The angle of the wafer 3 is 0 degrees as a reference when it directly faces the radiation thermometer 7, and as described above, the viewing window for the radiation thermometer also serves as an opening. In addition, the measurement wavelength of the radiation thermometer 7 is 0.9
μm, half width is 50μm, effective diameter of lens is 20-1
The ratio of the measurement ratio ML to the measurement diameter is L/L)=500. Further, assume that an extremely thin oxide film of 10 μm or less is formed on the surface of the wafer 3.

- The temperature was calculated as 1000° C., and the emissivity for a wavelength of 0.9 μm was calculated as 0.675. According to the results of this calculation, the angle of the wafer 3 is ±0.8, as shown in FIG.
It can be seen that even a very small change in temperature, such as a temperature of 1.5 degrees, results in a measured value higher than the actual temperature of the wafer 3 due to stray light. What about the code 7a? l+q constant optical path.

From the above, in order to take advantage of the fact that the wafer is a mirror surface and prevent errors caused by stray light when heating the wafer, it is necessary to accurately set the angle of the wafer to the radiation thermometer to a predetermined value. becomes.

However, in the conventional semiconductor heat treatment bag (C), the structure is such that the wafer is simply supported by a quartz jig, and no consideration is given to maintaining the wafer at an appropriate angle during heat treatment, as mentioned above. There wasn't.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a semiconductor heat treatment apparatus equipped with a radiation ap+u apparatus capable of minimizing errors caused by stray light and improving wafer temperature accuracy. With the goal.

[Means for Solving Problem 7a] In order to achieve the above object, the present invention provides a semiconductor heat treatment bag in which a semiconductor wafer mounted on a heat-resistant jig is housed and heat-treated in a heating space surrounded by heating means. t, a radiation thermometer that detects thermal radiation on the surface of the semiconductor wafer; an angle measuring means that determines the angle of the surface to be measured of the semiconductor wafer with respect to the measurement optical path of the radiation thermometer; A radiation a+++ h, h device is provided, which has a thermometer or an angle adjusting means for adjusting the angle of the semiconductor wafer and bringing the angle to a predetermined value.

Further, the angle measuring means includes an illumination means for irradiating the target surface 81j of the semiconductor wafer with a beam that substantially coincides with the alII fixed optical path of the radiation thermometer, and an optical element that receives the reflected light reflected from the surface to be measured. It consists of

Furthermore, the light source of the illumination means has wavelength characteristics different from the dll constant wavelength of the radiation thermometer, and the optical element is sensitive only to the wavelength of this light source.

Alternatively, processing means may be provided to convert the beam emitted from the illumination means into intermittent light having a constant period, and the optical element may be sensitive only to the intermittent light having the same period as this beam.

Further, the angle adjustment means may be configured by providing a heat-resistant jig with a plurality of nozzles that blow out inert gas in a flow pattern.

[Effect]

According to the above configuration, first, the wafer to be heat-treated is taken out of the cassette and transferred onto the heat-resistant jig, and while supported by the heat-resistant jig or the inert scum blown out from the heat-resistant jig, the wafer is transported into the heat treatment chamber by the wafer transport means. insert. At this time, a beam is emitted from the light source of the illumination means provided in the wafer angle measuring means along the measurement optical path of the radiation thermometer to illuminate the wafer, and the reflected light from the wafer surface is received by the optical element. The position where the optical element receives the reflected light,
That is, a signal dependent on the wafer angle is output, and based on this output signal, the wafer angle is corrected by the angle adjustment means so that the wafer is at a predetermined angle. At this time, if the wafer is deviated from a predetermined angle and one reflected light does not return to the light-receiving surface of the light-receiving element, change the angle of the wafer appropriately so that the reflected light enters the light-receiving surface. After that, the wafer angle is adjusted based on the output of the light receiving element as described above.

Also, during heat treatment of the wafer, if the reflected light deviates from the center of the light-receiving surface of the optical element, the wafer may be placed in a heat-resistant jig based on the output signal from the optical cable f-. Use the same method to return the angle to its proper value! Make 1ul1.

Due to the above-mentioned action, the angle of the wafer is always adjusted to a predetermined value, and its temperature can be measured using a radiation thermometer! ! +
By setting q, measurement without stray light can be performed.

〔Example〕

An embodiment of the semiconductor heat treatment apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. FIG. 1 shows a single wafer heat treatment apparatus, in which an infrared lamp 1 is provided at the outer station of a reaction tube 2, and a quartz lamp is placed inside the reaction tube 2. A cap 4 made of quartz is placed on the 6 reaction tube 2 in which the wafer 3 placed on a heat-resistant jig 5 made of quartz is housed.
A viewing window without an infrared lamp 1 is installed on the outer periphery of the reaction tube 2 facing the wafer 3 to prevent the temperature inside the reaction tube 2 from becoming uneven due to heat radiation to the outside. 6 is provided, and the temperature of the wafer 3 is determined by a radiation thermometer "7" through the observation window 6. The heat-resistant jig 5 is also provided with a plurality of nozzles 5a. An inert gas heated to approximately the same temperature as the wafer 3 is supplied to the nozzle 5a from a gas supply device 8 through an introduction pipe 9, so that the wafer 3 is supported from below without contact.

The radiation thermometer 7 is provided outside the viewing window 6, and the radiation thermometer 7 is attached to a mrros table 10 whose mounting angle can be adjusted at a temperature of 0°C. Further, a He-Ne laser 11 is connected to the radiation thermometer 7 via an optical fiber 12, and the light emitted from the laser 11 is made to match the measurement optical path of the radiation thermometer 7 and is used as a probe beam 13. 7
The light is emitted through a condensing lens (not shown) provided in the . Further, a half mirror 14 is provided on the optical path of the probe beam 13, and the emitted probe beam 13 passes through the half mirror 142 and the reaction tube 2.
The surface of the wafer 3 is irradiated. The probe beam 13 reflected from the surface of the wafer 3 indicates that the wafer 3 is connected to the radiation thermometer 7 . If it is perpendicular to the l+q constant optical path, it will pass through the viewing window 6 and be reflected by the 11-f mirror 14, as shown in Figure 2.
The reflected light 15 enters the reflected light detection section 16 . A diaphragm 16c and a lens 16b provided in the reflected light detection section 16
The light passes through and is received at the center of the light receiving surface of the optical AI'r l 6a.

Next, the operation of this embodiment will be explained. When the wafer 3 is placed on the heat-resistant jig 5 for a distance of 7 m for heat treatment, the angle of the wafer 3 is not necessarily at right angles to the measurement optical path of the radiation thermometer 7.

Therefore, it is necessary to once adjust the angle of the wafer 3 so that it is perpendicular to the measurement optical path. In particular, if the angle of the wafer 3 is greatly deviated and the probe beam reflected light 15 does not return to the reflected light detection section 16, the angle of the wafer 3 is changed appropriately.

The wafer angle is adjusted to a range where the reflected light 15 is detected by the optical element 16a. Thereafter, adjustments are made so that the reflected light 15 is received at the center of the light receiving surface based on the output signal of the optical cable 16a, which will be described later. Further, once the reflected light 15 is detected by the optical probe 16a, the angle of the wafer 3 is corrected so that the reflected light is always detected at the center of the element light-receiving surface, and the same operation is performed even during heat treatment. Therefore, the wafer 3 is always kept perpendicular to the measurement optical path of the radiation thermometer.

Next, the operation of the reflected light detection section 16 will be explained.

This reflected light detection section 16 includes a lens 16b and an aperture 16c.
Although not necessarily required in principle, they are used for the following reasons. That is, the lens 16b is the optical element 1.
It is used to widen the angle measurement range that is determined by the size of the light receiving surface of 6a.

Furthermore, it is necessary to minimize the amount of light incident on the optical element 16a other than the probe beam 13, that is, the amount of light received by the optical probe 16a among the thermal radiation of the wafer 3. Therefore, using the aperture 16c, the probe beam 1 is
Only light including reflected light 15 of the probe beam emitted from the portion irradiated with probe beam 3 is made to enter the optical element 16a. This optical element 16 uses elements that sense light arranged in an array, and receives the reflected light 15 that has passed through the opening of the lens 16b and the aperture 16c. At this time, the aperture 16c is placed at the focal point of the lens 16b, and as shown in FIGS. 3 to 5, the position of the light received by the optical element 16a changes depending on the angle of the incident reflected light 15, and the optical The angle of the reflected light 15 can be detected by the element 16a.

On the other hand, in order to change the angle of the wafer 3 placed on the heat-resistant jig 5, the inert gas blown out from the plurality of nozzles 5a provided on the heat-resistant jig 5 is controlled by the optical element 16a. It is changed for each nozzle according to the angle of the detected reflected light 15.

The wafer 3 may be supported at a predetermined angle without contact.

According to the present embodiment, the angle of the wafer 3 with respect to the measurement optical path of the radiation thermometer 7 is constantly determined by the reflected light detection unit 16, which stabilizes all angles, and based on the measurement result, the angle of the wafer 3 with respect to the measurement optical path of the radiation thermometer 7 is Nozzle 5 formed on tool 5
By changing the flow of inert gas blown out from a, the angle of the wafer 3 is controlled so that it always maintains a predetermined value. Since sources of heat radiation such as the infrared lamp 1 and the furnace wall are no longer located, temperature measurement errors due to stray light can be minimized, and the accuracy of temperature measurement of the wafer 3 can be improved.

Note that the wavelength characteristic of the laser 11 is different from the 1llq constant wavelength of the radiation thermometer 7, and the optical probe 16a is sensitive only to the wavelength of this laser 11, or the beam 13 emitted from the laser 11 is made into an intermittent light with a constant period. It is preferable that the optical element 16a is sensitive only to intermittent light having the same period as the beam 13.

FIG. 2 shows a schematic structure of a batch type diffusion device according to another embodiment of the present invention, and the same or equivalent parts as in the first embodiment shown in FIG. omitted.

In this embodiment, a heat-resistant jig 5 supporting a plurality of wafers 3 substantially in parallel is placed on a fork 5a, these are inserted into a reaction tube 2, and the SiC
It is heated by a heater 1 via a tube 2a.

Further, the heat radiation emitted by the wafer 3 whose temperature is to be measured is bent by a prism 17 provided on the fork 5a adjacent to the wafer 3, passed through the gap between the heat-resistant jig 5 and the fork 5a, and then passed through the reaction tube. Take it outside of 2 and measure the radiation thermometer 7.
It is designed to receive light and measure temperature. Also,
Radiation 11. The rotor 7 is attached via a fine movement table 10 to one end of a fork support mechanism 8a to which a fork 5a is attached. In order to change the angle of the wafer 3, it is sufficient to change the inclination of the fork 5a using this fork support mechanism 8a. It is similar to

This embodiment also has the same effects as the first embodiment.

In each of the above embodiments, a case has been described in which the semiconductor wafer 3 is heat-treated by the semiconductor heat-treating apparatus, but similar effects can be obtained for a measurement target other than a wafer if the surface to be measured can be regarded as a mirror surface.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent the source of thermal radiation from being located in a direction that is mirror-symmetrical to the radiation thermometer with respect to the normal to the wafer. can be minimized and the accuracy of wafer temperature measurement can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention, and FIGS. 3 to 5 are sectional views showing the action of the reflected light detection section. FIGS. 6 and 7 are cross-sectional views showing conventional means for eliminating stray light when the radiation side is heated, respectively, and FIG. 81! ! 1 is a sectional view showing an experimental apparatus for measuring errors due to stray light caused by changes in the angle of the wafer in the furnace, and FIG. 9 is a graph showing the experimental results. 1... Infrared lamp (heating means), 2... Reaction tube (
heating space), 3... wafer, 5... heat resistant jig, 5a
... Nozzle (angle adjustment means), 7... Radiation hygrometer,
7a...Measurement optical path, 11...Laser (light source), 13
...Probe beam, 15...Reflected light, 16...
Reflected light detection part leopard 1 time ¥J 3 eyes/Δc--system missing 6I21 foil 7 % 8 opening ? eye wafer i11 seat, (at))

Claims (1)

[Claims] 1. In a semiconductor heat treatment apparatus in which a semiconductor wafer mounted on a heat-resistant jig is housed in a heating chamber surrounded by heating means and heat-treated, the heat radiation on the surface of the semiconductor wafer is a radiation thermometer for detecting a radiation thermometer, an angle measuring means for measuring an angle of a surface to be measured of the semiconductor wafer with respect to a measurement optical path of the radiation thermometer, and adjusting an angle of the radiation thermometer or the semiconductor wafer to obtain a predetermined angle. What is claimed is: 1. A semiconductor heat treatment apparatus, comprising: a radiation temperature measurement device having angle adjustment means for adjusting a value. 2. The angle measuring means shall consist of an illumination means that irradiates the surface to be measured of the semiconductor wafer with a beam that substantially coincides with the measurement optical path of the radiation thermometer, and an optical element that receives reflected light reflected from the surface to be measured. The semiconductor heat treatment apparatus according to claim 1, characterized in that: 3. The semiconductor heat treatment apparatus according to claim 2, wherein the light source of the illumination means has wavelength characteristics different from the measurement wavelength of the radiation thermometer, and the optical element has sensitivity only to the wavelength of this light source. 4. The semiconductor heat treatment apparatus according to claim 2, further comprising processing means for converting the beam emitted from the illumination means into intermittent light having a constant period, and the optical element having sensitivity only to the intermittent light having the same period as this beam. . 5. The semiconductor heat processing apparatus according to claim 1, wherein the angle adjusting means is a plurality of nozzles provided on the heat-resistant jig and blowing out inert gas at a variable flow rate.