JP5169055B2 - Semiconductor wafer heat treatment equipment - Google Patents

Description

  The present invention relates to a semiconductor wafer heat treatment apparatus used for, for example, preheating in photoresist ashing (ashing), amorphous silicon film formation (CVD) on a glass substrate, or baking a photoresist. About.

  Currently, for example, in a semiconductor device manufacturing process, for example, in order to perform impurity diffusion processing or film formation processing on a semiconductor wafer, for example, a target processing can be performed simultaneously (collectively) on a large number of semiconductor wafers. A batch-type heat treatment apparatus is known, and in such a heat treatment apparatus, for example, a wafer holder that holds a plurality of semiconductor wafers in a vertical direction at a predetermined interval (pitch) in a horizontal state. The semiconductor wafer is heated to a predetermined processing temperature, for example, about 900 to 1200 ° C. by the heating means in a state where it is accommodated in the processing chamber and a predetermined processing gas is introduced into the processing chamber. Is done.

  In a certain type of such a heat treatment apparatus, for example, as shown in FIG. 3, a large number of light radiation heaters 40 each formed of an annular halogen lamp are arranged in parallel along the processing chamber 45 at predetermined intervals. It is set as the structure provided with the heating means comprised by arranging (refer patent document 1).

  In the case of performing preheating such as ashing of the photoresist (ashing process), film formation of amorphous silicon on the glass substrate (CVD), baking process of the photoresist, etc. by the light irradiation type heat treatment apparatus as described above. Therefore, it is necessary to heat-treat the object to be processed at a temperature lower than the above-described processes such as silicon oxide film formation and impurity diffusion, for example, about 100 to 500 ° C.

  However, in the above heat treatment apparatus, for example, when an object to be treated such as a semiconductor wafer (silicon wafer) PW made of silicon is heated in a temperature range of about 100 to 500 ° C., silicon close to the light radiation heater 40 is used. The outer edge portion of the wafer PW becomes high temperature, while the central portion of the silicon wafer PW far from the light radiation heater 40 has a lower temperature than the outer edge portion, and the temperature distribution on the surface of the silicon wafer PW is uniform. It has been found that there is a problem in that it cannot be heated to a state.

In general, as shown in FIG. 4 (a), silicon (Si) tends to have higher transmittance (lower absorbance) as the wavelength increases, that is, for example, light on the shorter wavelength side than 1.1 μm is absorbed. It is known that the ratio of transmitted light is high, and light having a longer wavelength than 1.1 μm exhibits a light transmission characteristic that increases the ratio of transmission.
Further, not only silicon (Si) but also gallium arsenide (GaAs (FIG. 4 (b))), germanium (Ge (FIG. 4 (c))), etc., the same tendency is observed. ) Has a higher light transmittance on the longer wavelength side than 0.8 μm, for example, and germanium (Ge) has a higher light transmittance on the longer wavelength side than, for example, 1.8 μm.
On the other hand, in filament lamps such as halogen lamps and incandescent lamps, as shown in FIG. 5, the wavelength peak radiated from the filament lamp moves to the longer wavelength side and becomes longer as the color temperature of the filament during lighting decreases. The ratio of the radiation intensity of the light on the wavelength side increases. Therefore, a state where a high light output is obtained for light having a short wavelength of 1.1 μm or less absorbed by the silicon wafer PW, that is, a state where the color temperature of the filament is high (for example, 3000 K, the wavelength peak is about 0.9 to 1 μm). When the silicon wafer PW is heated by the filament lamp 40, most of the light emitted from the filament lamp 40 is absorbed at the outer edge of the silicon wafer PW, so that the amount of light reaching the center is small. As a result, the degree of heating of the central portion of the silicon wafer PW becomes low, and the temperature distribution in the surface on the silicon wafer PW varies.
Specifically, for example, the temperature difference between the central portion and the outer edge portion of the silicon wafer PW may be 50 ° C. or more, and such a problem is caused by, for example, processing of a large-diameter silicon wafer having a diameter of φ300 mm. When doing it, it becomes prominent.

JP 2001-156008 A

  The present invention has been made on the basis of the above circumstances, and is configured so that a plurality of semiconductor wafers can be processed at one time. It is an object of the present invention to provide a semiconductor wafer heat treatment apparatus that can be performed in a state where uniformity in a plane and uniformity between semiconductor wafers are high.

The semiconductor wafer heat treatment apparatus of the present invention accommodates a wafer holder in a state in which a semiconductor wafer is held in a processing container having an inner surface as a reflection surface, and heats it by a filament lamp provided in the processing container. In the semiconductor wafer heat treatment apparatus for performing the heat treatment of the semiconductor wafer,
The wafer holder has a plurality of wafer holders for holding a plurality of semiconductor wafers in a state of being separated from each other in the vertical direction,
The filament lamp is a straight tube type in which a filament made of a tungsten wire is disposed, and the tube axis is disposed around the wafer holder in a posture in which the tube axis extends in a vertical direction.
When the heat treatment is performed, a simulated thermocouple is connected to the wafer holders located above and below the wafer placement area on which the semiconductor wafer to be treated is placed in the wafer holder. A semiconductor wafer is placed,
It has means for controlling the magnitude of power supplied to the filament lamp to turn on the filament lamp so that the color temperature of the filament becomes 2000K or less.

  According to the semiconductor wafer heat treatment apparatus of the present invention, the inner surface of the processing vessel is a reflection surface, and the filament lamp is radiated from the filament lamp by being turned on so that the color temperature of the filament is 2000K or less. Since most of the light that passes through the semiconductor wafer passes through all of the semiconductor wafers, light irradiation is performed under substantially uniform conditions within the plane of the semiconductor wafer and between the semiconductor wafers, and is emitted from the filament lamp. As a result of the light being gradually absorbed by the semiconductor wafer in the process of multiple reflection in the processing container, the desired heat treatment can be performed with a uniform temperature distribution on all the semiconductor wafers. .

  In addition, the filament lamp is of a straight tube type, and its tube axis extends in the vertical direction, and is arranged around the wafer holder so that light from the filament lamp can be transmitted to the wafer. Since it can be guided between the semiconductor wafers held by the holder at a predetermined interval and light can be irradiated on all the semiconductor wafers under substantially uniform conditions within the surface of the semiconductor wafer and between the semiconductor wafers, The desired heat treatment can be performed reliably in a state where the temperature distribution of the semiconductor wafer is uniform.

In addition, simulated semiconductor wafers are placed on the wafer holders located above and below the wafer placement area where the semiconductor wafer to be processed is placed, where the light incident conditions are significantly different from those of other wafer holders. As a result, the semiconductor wafer to be a product can be subjected to predetermined heat treatment under substantially the same conditions, so that the uniformity within the surface of the semiconductor wafer and the uniformity between the semiconductor wafers A high state is reliably obtained.
In addition, the magnitude of the power supplied to the filament lamp is controlled based on the temperature data detected by the thermocouple provided on the simulated semiconductor wafer so that the semiconductor wafer is in the set temperature state. This heat treatment can be performed reliably.

FIG. 1 is a cross-sectional view schematically showing a configuration of a main part in an example of a semiconductor wafer heat treatment apparatus of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG.
This semiconductor wafer heat treatment apparatus includes a cylindrical inner tube (belger) 11 that is disposed so as to extend in the height direction (vertical direction in FIG. 1), with the upper end closed and the lower end open. A processing vessel 10 having a double tube structure including a cylindrical outer tube 12 having a closed upper end and concentrically arranged around the periphery at a predetermined interval is provided.
Both the inner tube 11 and the outer tube 12 are made of, for example, quartz glass, and the inner surface of the outer tube 12 is made of, for example, aluminum, gold, or stainless steel, for example, in a wavelength range of 1.1 to 3.0 μm. A reflection surface 12A that reflects 60% or more of the light is formed.

Below the processing container 10, there is provided an elevating mechanism 15 that is driven in the vertical direction to carry the wafer holder 20 into and out of the processing container 10 (inner tube 11). The processing chamber S is formed inside the inner tube 11 by closing the lower end opening of the processing container 10 by the bottom plate 16.
Further, the mounting surface of the wafer holder 20 on the bottom plate 16 is also formed with a reflecting surface 16 </ b> A similar to the inner surface of the outer tube 12.

The wafer holder 20 is made of, for example, quartz glass, and a plurality of, for example, about 14 semiconductor wafers, for example, a silicon wafer PW having a diameter of φ300 mm, is in a horizontal state with a predetermined interval (pitch), for example, 9.5 mm. A wafer holding portion is formed so as to be held in multiple stages vertically at intervals.
In the wafer holder 20, the wafer holders located at the upper and lower parts of the wafer placement area on which the silicon wafer PW as a product is placed, for example, the wafer holders located at the uppermost part and the lowermost part, For example, a dummy wafer DW, which is a simulated semiconductor wafer to which a thermocouple is connected, is disposed.

In the semiconductor wafer heating processing apparatus, the silicon wafer PW accommodated in the processing chamber S is heated to a predetermined processing temperature in an annular space formed between the inner tube 11 and the outer tube 12 in the processing container 10. A filament lamp 30 is installed.
In this embodiment, as shown in FIG. 2, for example, twelve straight tube type filament lamps 30 are spaced apart at equal intervals along the circumferential direction, for example, with the tube axis extending in the vertical direction. It is installed to surround the inner pipe.
Each filament lamp 30 includes, for example, an arc tube made of, for example, a glass material having sealing portions formed at both ends. For example, a halogen gas is sealed in an internal space of the arc tube, and, for example, a tungsten element. A coiled filament 31 formed by winding a wire in a coil shape is disposed so as to extend along the tube axis of the arc tube.

As long as the filament 31 in each filament lamp 30 is configured so that the color temperature of the filament 31 when the lamp is lit is at least about 2000K, the wire diameter, coil diameter, coil pitch, length, and other specific configurations Although there is no particular limitation, for example, the length of the filament 31 is preferably such that the light is uniformly irradiated over the entire height direction of the wafer holder 20.
As an example of the configuration of the filament lamp 30, for example, the filament 31 has a length of 40 cm, a rated power of 1 kW, and a rated voltage of 200V.

Next, heat treatment performed on the silicon wafer PW performed in the semiconductor wafer heat treatment apparatus will be described.
After the wafer holder 20 in a state where the silicon wafer PW is held is placed on the bottom plate 16, the bottom plate 16 is driven upward by the elevating mechanism 15, and the wafer holder 20 is moved from the lower end opening to the processing container 10 ( While being carried into the inner tube 11), the bottom plate 16 hermetically closes the lower end opening of the processing vessel 10. As described above, for example, the dummy wafer DW is placed on the uppermost and lowermost wafer holders of the wafer holder 20.
Then, after the inert gas replacement or evacuation of the atmosphere in the processing chamber S is performed as necessary, the filament lamp 30 mainly emits light having a wavelength that transmits the silicon wafer PW that is the object to be processed. The silicon wafer PW is heated by being turned on so that the color temperature of the filament 31 is 2000 K or lower. Here, “mainly radiated” means that the ratio of light having a wavelength that passes through the silicon wafer PW is 88% or more (light having a wavelength absorbed by the silicon wafer PW is 12% or less).
When the filament lamp 30 is turned on so that the color temperature of the filament 31 is higher than 2000K, the ratio of light having a wavelength absorbed by the silicon wafer PW is increased, so that the outer edge of the silicon wafer PW close to the filament lamp 30 Since the amount of light absorbed in the wafer increases, the temperature distribution of the silicon wafer PW varies.

  The heat treatment for the silicon wafer PW is performed, for example, on the uppermost part and the lowermost part of the wafer holder 20 in accordance with a correlation pattern (temperature profile) between the temperature of the dummy wafer DW and the applied voltage to the filament lamp 30 acquired in advance. The magnitude of the applied voltage (supply power) to the filament lamp 30 is adjusted based on temperature information detected by the thermocouple provided on the dummy wafer DW. Here, the correlation pattern (temperature profile) is obtained by, for example, performing a heat treatment under the processing conditions for the silicon wafer PW that is an actual product, using a dummy wafer DW in which a thermocouple is embedded.

The temperature control during the heat treatment will be specifically described. By detecting that the dummy wafer DW has reached a predetermined temperature, the power supplied to each filament lamp 30 is reduced (suppressed small), or By stopping the supply, a predetermined temperature state is maintained. For example, when the inside of the processing chamber S is in a vacuum state, the heat radiation from the silicon wafer PW is performed gently, so that even when the power supply to the filament lamp 30 is stopped, the temperature of the silicon wafer PW is The heat treatment is performed while the temperature of the silicon wafer PW is maintained within a predetermined temperature range.
Moreover, the lighting control of the filament lamp 30 may be performed according to the temperature range required for the desired heat treatment. For example, when the temperature range is relatively wide, power supply to the filament lamp 30 is stopped. On the other hand, when the temperature range is relatively narrow, power necessary to maintain the silicon wafer PW at a predetermined temperature state is supplied. Is done.

Thus, in the semiconductor wafer heat treatment apparatus, when the filament lamp 30 is turned on so that the color temperature of the filament 31 is 2000K or less, the light emitted from the filament lamp 30 is as shown in FIG. The ratio of light having a wavelength peak of, for example, 1.4 to 1.5 μm and a wavelength of 1.1 μm or more is 88% or more, and most of the light is transmitted through the silicon wafer PW and emitted.
That is, the light from the filament lamp 30 (indicated by a two-dot chain line in FIG. 1) passes through the inner tube 11 constituting the processing vessel 10 and is incident on the silicon wafer PW. While passing through the silicon wafer PW and repeatedly entering and passing through the other silicon wafer PW, the light passes through the inner tube 11, and then on the reflecting surface 12 </ b> A formed on the inner surface of the outer tube 12 or the inner surface of the bottom plate 16. Then, the light is reflected by the reflecting surface 16 </ b> A formed and is introduced into the processing chamber S again.
Then, in the process in which the light emitted from the filament lamp 30 is multiple-reflected in the processing chamber S, the light is substantially uniform in the plane of the silicon wafer PW and between the silicon wafers PW for all silicon wafers PW. As a result of the fact that the irradiation is performed and the silicon wafer PW is gradually absorbed, as shown in the result of an experimental example described later, the desired heat treatment is uniformly performed on each silicon wafer PW. For example, the temperature difference in the temperature distribution on the silicon wafer PW, which is an allowable range in the state-of-the-art line for manufacturing semiconductors, is 2% or less.

  In addition, according to the semiconductor wafer heat treatment apparatus, the filament lamp 30 is of a straight tube type, and the tube axis is arranged around the wafer holder 20 in a posture that extends in the vertical direction. As a result, the light from the filament lamp 30 is guided between the silicon wafers PW held by the wafer holder 20 at a predetermined interval, and all the silicon wafers PW are within the plane of the silicon wafer PW and between the silicon wafers PW. Since light irradiation can be performed under substantially uniform conditions, the desired heat treatment can be performed more reliably in a state where the temperature distribution of the silicon wafer PW is uniform.

In addition, dummy wafers DW are arranged in wafer holding units positioned at the upper and lower portions of the wafer mounting region on which a silicon wafer PW as a product is placed, which is significantly different from the other wafer holding units. As a result, the silicon wafer PW that is a product can be more reliably subjected to the desired heat treatment under substantially uniform conditions. Therefore, the uniformity within the surface of the silicon wafer PW and the silicon wafer can be obtained. A state with high uniformity between PWs can be reliably obtained.
Further, the magnitude of the power supplied to the filament lamp 30 according to a preset temperature profile so that the silicon wafer PW is set to a set temperature state based on temperature data detected by a thermocouple provided on the dummy wafer DW. Therefore, the desired heat treatment can be performed reliably and easily.

Hereinafter, experimental examples performed for confirming the effects of the present invention will be described.
Using the semiconductor wafer heat treatment apparatus having the configuration shown in FIGS. 1 and 2, 14 silicon wafers (product wafers) having a diameter of 300 mm are placed on the wafer holder and positioned at the uppermost and lowermost positions. In a state where the dummy wafer was placed on the wafer holding portion (full load state), the wafer holder was carried into the processing chamber and heat treatment was performed so that the temperature of the product wafer was 200 ° C. Here, each filament lamp had a rated power of 1 kW and a rated voltage of 200 V, and was lit under the condition that the color temperature of the filament when the lamp was lit was 2400K.
The temperature difference between the maximum temperature and the minimum temperature on the silicon wafer when the temperature at a specific measurement location of the silicon wafer reaches 200 ° C. during the heat treatment, and the temperature uniformity within the surface of the silicon wafer is measured. Examined. The results are shown in Table 1 below.

Further, by adjusting the number of filament lamps and lighting under conditions (driving power) where the total amount of radiant energy (power density) is the same, the color temperature of the filament during lighting is adjusted according to the following Table 1, and the above The same experiment was conducted. The results are shown in Table 1 below.
In Table 1 below, for example, the temperature difference is “4 ° C.” because the maximum temperature is 202 ° C. and the minimum temperature is 198 ° C. when the temperature of a specific measurement location on the silicon wafer reaches 200 ° C. The temperature difference (error relative to the processing temperature) [%] is described as “1%” from 2/200 × 100 (%).

As described above, when the filament lamp is turned on so that the color temperature of the filament is 2000K or less, the temperature difference in the surface of the silicon wafer can be reduced to 2% or less, and the temperature distribution of the silicon wafer is uniform. It was confirmed that it was possible to heat in the state.
The same result was obtained for all silicon wafers regardless of the position in the height direction of the wafer holder. That is, it was confirmed that the desired heat treatment can be performed with high uniformity between silicon wafers.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, A various change can be added.
For example, if the filament lamp is arranged in the processing chamber, the light emitted from the filament lamp can be multiple-reflected in the processing chamber, so there is no need for a plurality of filament lamps. It does not need to be arranged on the outer periphery of the silicon wafer. Furthermore, the filament lamp may be of a both-end sealed type or a one-end sealed type.
Further, the temperature control during the heat treatment may be performed by using a temperature measuring unit such as a radiation thermometer and performing feedback control of temperature information obtained by the temperature measuring unit.
Furthermore, the present invention is not limited to a so-called vertical heat treatment apparatus, and the processing container is disposed so as to extend in the horizontal direction and the semiconductor wafers are held in a horizontal state in a vertical state. The present invention can also be applied to a horizontal heat treatment apparatus housed inside.

It is sectional drawing which shows roughly the structure of the principal part in an example of the semiconductor wafer heat processing apparatus of this invention. It is the sectional view on the AA line in FIG. It is sectional drawing which shows the structure in an example of the conventional light irradiation type heat processing apparatus. It is a graph which shows the light transmission characteristic of Si (b), GaAs (b), and Ge (c). It is a graph which shows a radiation spectrum in case the total radiant energy (lamp power density) is made the same.

Explanation of symbols

10 Processing container 11 Inner pipe (Berja)
DESCRIPTION OF SYMBOLS 12 Outer tube 12A Reflection surface 15 Elevating mechanism 16 Bottom plate 16A Reflection surface 20 Wafer holder 30 Filament lamp 31 Filament 40 Heater for light radiation heating 45 Processing chamber PW Silicon wafer DW Dummy wafer S Processing chamber

Claims (1)

The wafer holder in a state where the semiconductor wafer is held is accommodated in a processing container having an inner surface as a reflection surface, and heated by a filament lamp provided in the processing container, thereby performing the heat treatment of the semiconductor wafer. In semiconductor wafer heat treatment equipment,
The wafer holder has a plurality of wafer holders for holding a plurality of semiconductor wafers in a state of being separated from each other in the vertical direction,
The filament lamp is a straight tube type in which a filament made of a tungsten wire is disposed, and the tube axis is disposed around the wafer holder in a posture in which the tube axis extends in a vertical direction.
When the heat treatment is performed, a simulated thermocouple is connected to the wafer holders located above and below the wafer placement area on which the semiconductor wafer to be treated is placed in the wafer holder. A semiconductor wafer is placed,
A semiconductor wafer heat treatment apparatus comprising means for controlling the magnitude of power supplied to the filament lamp to turn on the filament lamp so that the color temperature of the filament is 2000K or less.

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