JPH0324720A - Wafer processing method and processing equipment - Google Patents

Abstract

PURPOSE:To enable heat treatment at a high temperature and in a short time without generating crystal defect in the outer periphery of a wafer, by making the temperature of gas to be introduced into a processing vessel rise or fall in accordance with the temperature of the wafer. CONSTITUTION:The temperature of gas to be introduced into a processing vessel 11 is controlled in accordance with the temperature of a wafer 13 under heat treatment. That is, the temperature of the wafer 13 is measured with an infrared thermometer 23, and input to a controlling apparatus 18; the gas temperature is measured with a gas thermometer 20; a heater power source 19 is controlled by the controlling apparatus 18 in the manner in which the temperature of gas around the wafer rises or falls synchronizing with the rise or fall of the temperature of the wafer 13. By making the temperature of the gas to be introduced approach to that of the wafer 13, heat dissipation from the wafer 13 to the surrounding atmospheric gas can be restrained. Further, since the time necessary to introduce high temperature gas into the vessel 11 is saved, the temperature rise of the vessel 11 itself can be restrained. Thereby heat treatment at a high temperature and in a short time is enabled without generating crystal defect in the outer periphery of the wafer 13.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention heats a semiconductor wafer by light irradiation, oxidizes it, and
The present invention relates to a wafer processing method and processing apparatus that performs processes such as diffusion and nitridation.

(Prior Art) In recent years, in ultra-LSI devices, miniaturization and higher density of elements are progressing rapidly. In response to this, consideration is being given to incorporating high-temperature, short-time heat treatment using light irradiation heating using a halogen lamp or the like during the production process. For example, after introducing impurities into a silicon wafer, heat treatment is performed to restore crystallinity and activate the impurities. At that time, in order to suppress the redistribution of the impurities and form shallow junctions, light irradiation is used to suppress the redistribution of the impurities and form shallow junctions. The use of high-temperature, short-time heat treatment is being considered.

Further, gate insulating films are also becoming thinner and thinner, and it is required to form thin Sin2 films with good controllability. It is known that the insulation properties of thermal oxide films deteriorate as the oxidation temperature is lower, and rapid oxidation at high temperatures and short times using light irradiation heating is also being considered. Furthermore, it has been reported that a thin film with good insulating properties can be obtained by forming a thin SiO2 film and then performing rapid nitriding and rapid oxidation at a high temperature and for a short time by heating with light irradiation.

In the high-temperature, short-time heat treatment using light irradiation heating described above, silicon wafers housed in a reactor are heated from room temperature to l0
The temperature is raised to a high temperature of 00° C. or higher in about 10 seconds, and after the heat treatment is finished, the temperature is lowered to room temperature in about several minutes.

However, this type of method has the following problems. That is, when a wafer is subjected to heat treatment that involves rapid temperature rise and fall, crystal defects called slips often occur on the outer periphery of the wafer, and the wafer can no longer be used as a material for semiconductor devices. In particular, slipping always occurred when heat treatment was performed at a high temperature of 1050° C. or higher.

The cause of the occurrence of such crystal defects at the outer periphery of the wafer is considered to be as follows. In rapid temperature rise by light irradiation heating, only the wafer is heated to a high temperature, and the atmospheric gas around the wafer is not heated so much. Therefore, heat is dissipated into the atmospheric gas around the wafer, but the heat dissipation from the wafer outer circumference is much larger than the heat dissipation from the wafer center, and the temperature of the wafer outer circumference is lower than that of the center.

Furthermore, the radial temperature gradient is particularly large at the wafer periphery, and crystal defects occur at the wafer periphery due to strain stress due to differences in thermal expansion.

In order to prevent the occurrence of crystal defects at the outer periphery of the wafer, a known method is to heat the gas introduced into the reactor in advance to suppress the dissipation of heat from the wafer to the atmospheric gas around the wafer. .

However, this method has the following problems.

In order to prevent crystal defects from occurring on the wafer periphery,
It is necessary to heat the gas introduced into the reactor to a fairly high temperature. However, if high-temperature gas is continuously introduced into the furnace from the start to the end of the heat treatment, the temperature of the furnace itself will also rise.

Therefore, the time required to cool down the wafer after heat treatment becomes long, making it difficult to control the heat treatment time to a short time.

In actual production processes, the same heat treatment is often performed continuously, making it even more difficult to control the heat treatment time to a short time.

(Problems to be Solved by the Invention) Conventionally, when heat treatment is performed at a high temperature and for a short time using light irradiation, there has been a problem in that crystal defects called slips occur at the outer peripheral portion of the wafer. In addition, in order to prevent the occurrence of crystal defects on the outer periphery of the wafer, if the gas introduced into the reactor is preheated to a high temperature, the temperature of the reactor itself will also rise, resulting in a longer cooling down time after the heat treatment is completed. Therefore, it was difficult to control the heat treatment time to a short time.

The present invention has been made in consideration of the above circumstances, and its purpose is to provide a semiconductor wafer that can be heat-treated at high temperature and for a short time by light irradiation without causing crystal defects on the outer periphery of the wafer. The purpose is to provide a processing method.

Another object of the present invention is to provide a wafer processing apparatus for carrying out the above method.

[Structure of the Invention] (Means for Solving the Problems) The gist of the present invention is to reduce heat dissipation from the outer peripheral portion of the wafer by increasing and decreasing the temperature of the gas according to the wafer temperature.

That is, the present invention provides a wafer processing method in which a predetermined gas is introduced into a processing container containing a semiconductor wafer, and the wafer is heated by irradiating light onto the surface of the wafer. This is a method in which the temperature is variably controlled according to the temperature of the wafer during heat treatment.

The present invention also provides a wafer processing apparatus for carrying out the above method, including a processing container containing a semiconductor wafer, means for introducing gas into the container, and heating the wafer by irradiating the surface of the wafer with light. and a means for raising and lowering the temperature of the gas introduced into the processing container in accordance with the temperature of the wafer undergoing heat treatment.

Furthermore, the present invention provides a plurality of gas containers adjacent to the processing container for introducing gas into the container as a means for raising and lowering the temperature of the gas, and the gas in each gas container is transferred to the wafer during heat treatment. The surface temperature is maintained at different temperatures between the lowest temperature and the highest temperature, and the gas container connected to the processing container is selected depending on the temperature of the wafer during heat treatment.

(Function) According to the present invention, when heating a semiconductor wafer by light irradiation, the temperature of the gas introduced into the processing container is raised or lowered in accordance with the wafer temperature during heat treatment (bringing it closer to the wafer temperature). It is possible to suppress the dissipation of heat from the wafer to the atmospheric gas around the wafer, and at the same time, it is possible to suppress the rise in temperature of the container itself by shortening the time during which high-temperature gas is introduced into the container. This makes it possible to perform heat treatment at a high temperature and for a short time without generating crystal defects on the outer periphery of the wafer.

Note that it is better to have a smaller difference between the temperature of the gas introduced into the processing container and the temperature of the semiconductor wafer surface, but according to experiments by the present inventors, if this temperature difference is kept within about 500°C, It has been found that the occurrence of crystal defects can be almost suppressed.

In addition, gas heated to each temperature from the lowest temperature to the highest temperature of the semiconductor wafer surface during heat treatment is prepared in advance in multiple gas containers, and the gases are sequentially introduced into the containers according to the temperature change of the wafer surface. This makes it possible to easily raise and lower the temperature of the gas introduced into the processing container in synchronization with the rise and fall of the temperature of the wafer.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic configuration diagram showing a wafer processing apparatus according to an embodiment of the present invention. In the figure, reference numeral 11 denotes a reactor (container) made of quartz glass, and a wafer 13 supported on a susceptor 12 is accommodated in the reactor 11. The reactor 11 is provided with a gas inlet 14 for introducing gas and a gas exhaust port 15 for exhausting the gas.

Gas introduced into the reactor 11 from the gas inlet 14 is supplied from a gas pipe 16 and heated by a gas heater 17. The gas heater 17 is powered by a heater power source 1 that operates according to a control command from a control device 18.
It is heated by electricity. Furthermore, a gas temperature meter 20 is installed between the gas inlet 14 and the gas heater 17 to measure the temperature of the gas. The gas temperature detected by the gas thermometer 20 is supplied to the control device 18.

On the other hand, a group of lamps 21 is installed around the outer periphery of the reactor 11 to heat the workpiece/\13 by irradiating light. The lamp group 21 is energized and emitted by a lamp power supply 22 that is operated in response to a control command from the control device 18 . Also, wafer 1
3 is detected by an infrared thermometer 23, and the detected temperature is supplied to the control device 18.

In addition, 24 in the figure is a furnace cover that closes the open end of the reactor 11, and 25
indicates the outer wall of the lamp chamber that accommodates the lamp group 21.

In such a configuration, in order to perform heat treatment for oxidation, nitridation, diffusion, etc. on a semiconductor wafer, the wafer 13 is first supported on the susceptor 12 and inserted into the reactor 11. Next, the wafer 13 is heated by the upper and lower lamp groups 19,
The temperature is raised to 1000°C or more in about 10 seconds. And 10
Heat treatment is performed by maintaining the lamp at a high temperature for about seconds to several minutes, and then the lamp power source 22 is turned off and the temperature is rapidly lowered.

During the heat treatment, the temperature of the wafer 13 is measured with an infrared thermometer 20, and the lamp power supply 22 is controlled by the controller 18 so that the temperature follows a predetermined temperature pattern. Gas piping 16
The atmospheric gas for heat treatment supplied from the reactor 11 is introduced into the reactor 11 from the gas inlet 14 via the gas heater 17 , passes around the wafer 13 , and then is exhausted from the gas exhaust port 15 . At this time, the gas temperature is measured by a gas thermometer 20 installed just before the gas inlet 14, and the control device 18 controls the reheater power supply 19 so that the gas temperature around the wafer rises and falls in synchronization with the temperature rise and fall of the wafer 13. control.

Here, in order to perform high-temperature, short-time heat treatment without generating crystal defects on the wafer's outer periphery, #J should be controlled so that the difference between the gas temperature and the wafer temperature is always maintained within 500°C. . Therefore, in this embodiment, the heater power supply 19 and lamp power supply 22 are controlled by the control device 18, thereby controlling the wafer temperature and the gas temperature as shown in FIG. That is, the lamp power supply 22 is driven based on the temperature measured by the infrared thermometer 23, the wafer temperature is raised from room temperature to 1200°C in about 10 seconds, this temperature is maintained for about 1 minute, and the lamp is turned off. The power supply 22 is turned off and the temperature is lowered. Furthermore, the heater power source 19 is driven based on the temperatures measured by the infrared thermometer 23 and the gas thermometer 20, and the temperature of the introduced gas is controlled to approach the wafer temperature.

In reality, the temperature of the gas does not rise as quickly as the temperature of the wafer, so the initial temperature of the gas is set to 100 to 30° below room temperature.
By increasing the temperature by about 0°C, it is possible to always maintain the difference between the wafer temperature and the gas temperature within 500°C, as shown in FIG.

In this way, by raising and lowering the gas temperature in accordance with the wafer temperature, the temperature difference between the wafer and the atmospheric gas can be reduced, and the temperature gradient in the radial direction can also be made gentler in the wafer peripheral area. Therefore, high-temperature, short-time heat treatment can be performed without generating crystal defects on the outer periphery of the wafer. Furthermore, since the time for flowing the high-temperature gas into the reactor is shortened, it is possible to suppress the temperature rise of the reactor itself, and thereby it is also possible to shorten the temperature-lowering time.

Note that in this embodiment, the gas thermometer 20 is connected to the gas inlet 14.
Although it is installed just before the reactor 11, it can also be installed near the wafer inside the reactor 11.

Furthermore, by flowing cooling water on or near the outer wall of the reactor 11, the temperature increase in the reactor 11 caused by lamp heating and high-temperature heat treatment atmosphere gas can be more effectively suppressed, and short-term controllability of heat treatment can be improved. is also possible.

FIG. 3 is a schematic configuration diagram showing another embodiment of the present invention.

Note that the same parts as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted.

This embodiment differs from the previously described embodiments in that a plurality of gas containers are provided in order to quickly switch the gas temperature. That is, the gas heater 1 in the previous embodiment
7 instead of 3 gas-heated thermal containers 31, 32.3
3 is installed. These containers 31 to 33 each include a heater that is energized and heated by a heater power source 19. The gases in each of the volumes 431 to 33 are heated to different temperatures from a minimum of 4 degrees Celsius to a maximum temperature of the wafer surface at +7.

In such a configuration, the gas heating and heat-insulating containers 31 to 33 are selected depending on the temperature change on the wafer surface, and the gas from the selected container or the gas supplied to the pipe 16 is transferred to the reactor 1.
Introduced within 1.

For example, when heating the wafer 13 to 1100°C, heat treatment atmosphere gas is heated and kept warm in advance at 1000°C in the gas heating heat-insulating container 31, at 700°C in the container 32, and at 300°C in the container 33. . When the wafer surface temperature is between room temperature and 100°C, the valve 37 is opened to supply gas at room temperature, and when it is between 100°C and 500°C, valve 36 is opened to supply gas at 300°C and 500°C. and 900
When the temperature is between 900°C and 1100°C, open the valve 35 to supply 700°C gas, and when the temperature is between 900°C and 1100°C, open the valve 34.
is opened and gas at 1000° C. is introduced into the reactor 11 through the gas inlet 14. Further, to obtain a desired temperature between these temperatures, gases in a plurality of containers may be mixed and used.

In this case, the gas temperature can be quickly switched, and the difference between the gas temperature and the wafer temperature can always be kept within 200°C. Therefore, not only the same effects as in the previous embodiment can be obtained, but also the occurrence of crystal defects at the outer periphery of the wafer can be more reliably prevented.

In this example, by adjusting the flow rate ratio and mixing two types of gas using a gas mass flow meter,
It is also possible to introduce gas at any temperature from ffi to 1000° C. into the reactor 11. Also, in Figure 3, three gas-heated heat-insulating containers are installed, but two or four
It goes without saying that more than one may be installed.

[Effects of the Invention] As detailed above, according to the present invention, by raising and lowering the temperature of the gas introduced into the processing container in accordance with the temperature of the wafer, high temperature can be achieved without generating crystal defects on the outer periphery of the wafer. Heat treatment can be performed for a short time.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a schematic diagram showing a wafer processing apparatus according to an embodiment of the present invention, and Fig. 2 is for explaining the operation of the above-mentioned apparatus. FIG. 3 is a schematic diagram showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 11... Reactor (processing container), 13... Semiconductor wafer, 14... Gas inlet, 15... Gas exhaust port, 7... Gas heater, 8... Control device, 9. ...Heater power source, O...Gas thermometer, 1...Lamp group, 2...Lamp power source, 3...Infrared thermometer, 1-33...Gas heating thermal insulation container.

Claims (2)

[Claims] (1) In a wafer processing method in which a predetermined gas is introduced into a processing container containing a semiconductor wafer, and the wafer is heated by irradiating light onto the surface of the wafer, the temperature of the gas introduced into the container is controlled. A wafer processing method characterized by variable control according to the temperature of a wafer during heat processing. (2) a processing container containing a semiconductor wafer; a means for introducing a predetermined gas into the container; a means for heating the wafer by irradiating the surface of the wafer with light; 1. A wafer processing apparatus comprising: means for raising and lowering the temperature of a gas in accordance with the temperature of a wafer undergoing heat treatment.