JP2008060560A - Annealing apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an annealing apparatus and an annealing method wherein a great optical power is generated by utilizing LEDs as a heat source. <P>SOLUTION: The annealing apparatus includes a process chamber 1 wherein an object W is disposed, heat sources 7a, 7b having a plurality of LED elements 33 with which light is irradiated onto the object W, a feeding device 10 for feeding electricity to the plurality of LED elements 33, cooling devices 6a, 6b and 20 for cooling the LED elements, and light transmitting members 5a, 5b disposed between the process chamber 1 and the heat sources 7a, 7b. In the apparatus 100, the object W is annealed by being irradiated with light emitted from the LED elements 33. The LED elements 33 are comprised of GaAs-based materials. A high optical output power is generated from the LED elements 33 driven with high current while the LED elements 33 are being cooled by the cooling devices 6a, 6b and 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an annealing apparatus and an annealing method for performing annealing by irradiating a semiconductor wafer or the like with light from an LED.

  In the manufacture of semiconductor devices, there are various types of heat treatment such as film formation, oxidation diffusion treatment, modification treatment, annealing treatment on a semiconductor wafer (hereinafter simply referred to as a wafer) that is a substrate to be processed. With the demand for higher speed and higher integration, annealing after ion implantation, in particular, is directed to higher temperature rise and fall in order to minimize diffusion. As an annealing apparatus capable of such high-speed temperature rising and cooling, an apparatus using an LED (light emitting diode) as a heat source has been proposed (for example, Patent Document 1). LED heating uses electromagnetic radiation due to recombination of electrons and holes, not black body radiation of the heating source, so there is a possibility that the temperature drop rate is high for heating wafers and the like and it can be applied to the most advanced processes. .

However, the LED element generally has a low energy density, and it is difficult to obtain a high power necessary for increasing the temperature at a high speed. In particular, GaN, which is widely used as an LED element that emits light with a short wavelength of ultraviolet light to blue light from the viewpoint of heating only the surface portion of the wafer, has a property that the optical power is saturated when the current value exceeds a predetermined value. In principle, large optical power cannot be extracted.
JP 2005-536045 gazette

This invention is made | formed in view of this situation, Comprising: It aims at providing the annealing apparatus and annealing method which can obtain big optical power using LED as a heat source.
It is another object of the present invention to provide a computer-readable storage medium for executing the annealing method.

  In order to solve the above-described problem, in a first aspect of the present invention, a processing container in which an object to be processed is accommodated, a heating source having a plurality of LED elements that irradiate light to the object to be processed, A power supply unit that supplies power to the LED element, a cooling unit that cools the LED element, and a light transmission member that is provided between the processing container and the heating source, and receives light emitted from the LED element. An annealing apparatus for irradiating a processing body to anneal a target object, wherein the LED element is made of a GaAs-based material, and the LED element is driven at a high current while cooling the LED element by the cooling means. An annealing apparatus characterized in that a high light output is obtained from the above.

  In the first aspect, the heating source may be provided on both sides of the processing container. The cooling means includes a housing in which the heating source is accommodated, and a cooling medium supply mechanism that supplies a cooling medium that has insulating properties and transmits light emitted from the LED element in the housing. It can be. In this case, a fluorine-based inert liquid can be used as the cooling medium. Furthermore, it is preferable that the cooling unit cools the LED element to 0 ° C. or less, and the power feeding unit sets a current flowing through the LED element to 100 mA or more.

  According to a second aspect of the present invention, there is provided an annealing method in which an object to be processed is accommodated in a processing container, a plurality of LED elements are supplied with power and turned on, and the object to be processed is annealed by the light. An annealing method comprising a material and emitting light from the LED element with high light output by high current driving while cooling the LED element is provided.

  In the second aspect, the cooling can be performed by directly contacting the LED element with a cooling medium that has insulating properties and transmits light emitted from the LED element. In this case, a fluorine-based inert liquid can be used as the cooling medium. Moreover, it is preferable that the said LED element is cooled to 0 degrees C or less, and the electric current sent through the said LED element shall be 100 mA or more.

  According to a third aspect of the present invention, there is provided a computer-readable storage medium in which a control program that operates on a computer is stored, and the control program performs the method according to the second aspect at the time of execution. A computer-readable storage medium characterized by causing a computer to control an annealing apparatus is provided.

  According to the present invention, when the object to be processed is annealed by irradiating the object to be processed from a plurality of LED elements constituting the heating source in a state where the object to be processed is accommodated in the processing container, A GaAs material is used. In the LED element composed of a GaAs-based material, if the current is increased, the light output can be increased by the capacity of the coupling layer and the quantum well, and the light output is substantially proportional to the current. Therefore, the LED element can be cooled to suppress a decrease in the amount of light emission due to heat generation of the LED element itself, and a high light output can be obtained by high current driving. Further, since the light output of the LED element composed of GaAs increases greatly as the temperature decreases, an increase in the light output due to the increase is added, and an extremely large light output can be obtained. Therefore, the object to be processed can be annealed with a large optical power.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, an example of an annealing apparatus for annealing a wafer having impurities implanted on the surface will be described.
FIG. 1 is a sectional view showing a schematic configuration of an annealing apparatus according to an embodiment of the present invention. The annealing apparatus 100 is hermetically configured and has a chamber (processing vessel) 1 into which a wafer W is loaded.

  A support column 2 is erected from the bottom of the chamber 1, and a support member 3 that horizontally supports the wafer W is provided so as to extend inward from the upper end of the support column 2. Openings 1a and 1b are formed in portions corresponding to the wafer W on the top wall and the bottom wall of the chamber 1, and the light transmitting members 5a and 5b are airtightly attached so as to cover the openings 1a and 1b. ing. Further, a processing gas introduction port 22 into which a predetermined processing gas is introduced from a processing gas supply mechanism (not shown) and an exhaust port 23 connected to an exhaust device (not shown) are provided on the side wall of the chamber 1. Further, a loading / unloading port 24 for loading / unloading the wafer W into / from the chamber 1 is provided on the side wall of the chamber 1, and the loading / unloading port 24 can be opened and closed by a gate valve 25. A temperature sensor 26 for measuring the temperature of the wafer W placed on the support member 3 is provided inside the chamber 1. The temperature sensor 26 is connected to a measurement unit 27 outside the chamber 1, and a temperature detection signal is output from the measurement unit 27 to a process controller 60 described later.

  A first housing 6a is provided on the top wall of the chamber 1 so as to surround the light transmission member 5a, and a second housing is provided below the bottom wall of the chamber 1 so as to surround the light transmission member 5b. A housing 6b is provided. Heating sources 7a and 7b each having a plurality of LED elements are accommodated in the housings 6a and 6b.

  The first housing 6a forms a holding member 28a that holds the periphery of the light transmission member 5a, and a space 30a that is provided in close contact with the holding member 28a and accommodates the cooling medium, and the cooling medium flows therethrough. And a copper heat dissipating member 29a having a cooling medium passage 31a. A heating source 7a is held on the lower surface of the heat dissipation member 29a.

  The second housing 6b forms a holding member 28b that holds the periphery of the light transmission member 5b and a space 30b that is provided in close contact with the holding member 28b and accommodates the cooling medium, and the cooling medium flows therethrough. And a heat radiating member 29b made of copper having a cooling medium passage 31b. A heating source 7b is held on the upper surface of the heat dissipation member 29b.

  As shown in an enlarged view in FIG. 2, the heat sources 7a and 7b are a plurality of LEDs in which a large number of LED elements 33 are mounted on a support member 32 made of a highly heat conductive material having insulation properties, typically AlN ceramics. These LED arrays 34 are arranged on the lower surface of the heat dissipating member 29a in the heating source 7a and on the upper surface of the heat dissipating member 29b in the heating source 7b. An electrode 35 is provided between the support member 32 of the LED array 34 and the LED element 33, and this electrode 35 is connected to a power supply member 36 that passes through the inside of the heat dissipation members 29a and 29b. A connection wire 37 connects between one LED element 33 and the electrode 35 of the adjacent LED element 33. The power supply unit 10 is connected to the power supply member 36 of the heating sources 7a and 7b via the power supply lines 10a and 10b, and is supplied with power to the LED elements 33 via the power supply member 36. Then, the LED element 33 emits light by supplying power to the LED element 33, and the wafer W is heated from the front and back surfaces by the light and annealed. These LED arrays 34 have a hexagonal shape, for example, and are arranged as shown in FIG. 3, for example. For example, about 2000 to 5000 LED elements 33 are mounted on one LED array 34. The LED element 33 is made of a GaAs material, for example, GaAs or GaAsAl.

  A cooling medium introduction port 11a and a cooling medium discharge port 12a are provided on the side wall of the first housing 6a, and a cooling medium introduction port 11b and a cooling medium discharge port 12b are provided on the side wall of the second housing 6b. Yes. Cooling medium supply pipes 13a and 13b are connected to the cooling medium introduction ports 11a and 11b, respectively, and cooling medium discharge pipes 14a and 14b are connected to the cooling medium discharge ports 12a and 12b. The cooling medium supply pipes 13a and 13b are connected to the cooling medium supply mechanism 20, and the cooling medium supply mechanism 20 causes liquids to enter the first and second housings 6a and 6b via the cooling medium supply pipes 13a and 13b. The cooling medium 21 is supplied, and the first and second housings 6 a and 6 b are filled with the cooling medium 21. Further, the cooling medium 21 of the first and second housings 6a and 6b is recovered via the cooling medium discharge pipes 14a and 14b. That is, the cooling medium 21 is circulated by the cooling medium supply mechanism 20.

  As the cooling medium 21, a liquid that has a cooling capability capable of sufficiently cooling the LED element 33, is insulative, and is transmissive with respect to the wavelength of light emitted from the LED element is used. Further, in order to prevent the light emitted from the LED element 33 from being totally reflected, the refractive index is larger than 1 and smaller than the GaAs-based material (refractive index of 3.6 in the case of GaAs) that constitutes the LED element. It is preferable to use these substances. From the viewpoint of efficiency, the transmittance with respect to the wavelength of light irradiated from the LED element is preferably 90% or more, and more preferably transparent (transmittance is approximately 100%) with respect to the light irradiated from the LED element. Examples of such substances include fluorine-based inert liquids (trade names such as florinate and galden). As shown in FIG. 4, the visible light transmittance of Fluorinert is almost 100%, and the refractive index is about 1.25.

  As shown in FIG. 1, the cooling medium 21 is in direct contact with the LED elements 33 constituting the heating sources 7a and 7b in the first and second housings 6a and 6b. The cooling medium 21 is also supplied to the cooling medium flow path 31a of the heat dissipation member 29a in the first housing 6a and the cooling medium flow path 31b of the heat dissipation member 29b in the second housing 6b. In addition to being cooled by the heat, the heat is also radiated to the heat radiating members 29a and 29b, so that the cooling is extremely efficient. The cooling temperature of the LED element 33 is preferably 0 ° C. or less.

  In addition, since the direct cooling medium 21 contacts the light emitting surface of the LED element 33, the gas (air) slightly dissolved in the cooling medium 21 becomes a bubble on the light emitting surface, and the light emitting efficiency of the LED element 33 is reduced. There is a risk of causing. For this reason, it is preferable to use the cooling medium 21 after performing deaeration and defoaming processing beforehand. As the deaeration and defoaming process at this time, the sealed container containing the cooling medium 21 may be simply evacuated with a vacuum pump.

  The LED element 33 is made of a GaAs-based material as described above, and examples of such a material include GaAs and GaAsAl. These materials are in the near infrared region where the center wavelength of the emitted light is about 950 to 970 nm, and the width of the emitted light band is as narrow as about 50 nm. The wafer W to be annealed is made of silicon, and its radiation (absorption) characteristics are as shown in FIG. 5, and the emissivity (absorption rate) is around 950 to 970 nm, which is the emission wavelength of the GaAs material. It is about .65, and its value is almost constant regardless of the temperature. GaN, which has been widely used as an LED element in the past, is in the ultraviolet to blue region where the center wavelength of the emitted light is about 360 to 520 nm, and the emissivity (absorption rate) of silicon at that emission wavelength is about 0.6. Light emitted from the system material is more absorptive.

  Further, in the case of an LED element made of a GaAs-based material, when GaAs is taken as an example, the voltage-current characteristics are as shown in FIG. 6, and the forward current largely changes depending on the change of the forward voltage. The change in forward current of conventional GaN is shown in FIG. 7. Since the change in forward current due to the change in forward voltage is smaller than that of GaAs, GaAs has a large necessity for current control.

  FIG. 8 is a diagram comparing the current-light output relationship when GaAs and GaN are used as LED elements. As shown in this figure, GaN saturates the light output from about 1.5 times the rated current (50 mA), whereas GaAs increases the light output in proportion to the current even when the rated current (50 mA) is exceeded. I understand that That is, in the LED element composed of GaAs, if the current is increased, the light output can be increased by the capacity of the coupling layer and the quantum well. However, since there is a decrease in the amount of light emission due to heat generation of the LED element itself, a large increase in light output cannot be obtained at room temperature. However, a large light output can be obtained by cooling with the cooling medium 21 as described above. In this case, the cooling temperature by the cooling medium is preferably 0 ° C. or lower in order to effectively suppress a decrease in the amount of light emission due to heat generation and obtain a sufficient light output. In addition, since the operation in the pulse mode is defined for the GaAs LED element, and the current value in that case is 1 A (room temperature), if the LED element 33 is cooled by the cooling medium 21 in this way, even in the continuous mode. It becomes possible to supply a current that is 1A and 20 times the rating, and an optical output that is 20 times higher can be obtained. From the viewpoint of obtaining an effective light output, the current value supplied to the GaAs LED element is preferably 100 mA or more.

  FIG. 9 is a diagram showing a comparison of the temperature-light output relationship when GaAs and GaN are used as LED elements. As shown in this figure, GaN does not change light output with temperature, whereas GaAs increases light output significantly when the temperature decreases, and it is about twice that at room temperature at -50 ° C. .

  That is, the cooling by the cooling medium 21 enables high-current driving and high light output while suppressing a decrease in light emission amount due to heat generation of the LED element itself, and in addition, a decrease in element temperature itself directly increases the light output. Therefore, an extremely large light output can be obtained by these two synergistic effects. For example, if the LED element 33 is cooled to −50 ° C. and a current of 1 A is applied, compared to the case where light irradiation is performed at the rated current at room temperature, the increase in current is 20 times, the effect due to temperature is twice, and the total is 40 times. Light output can be obtained. In the case of GaN, the increase in the light output with respect to the current value is saturated at about 1.5 times the rated current, and the light output does not increase due to a decrease in temperature. On the other hand, with a GaAs-based material, the light output can be dramatically increased by cooling the LED element and driving at a high current.

  As shown in FIG. 1, each component of the annealing apparatus 100 is connected to and controlled by a process controller 60 having a microprocessor (computer). Connected to the process controller 60 is a user interface 61 including a keyboard for a process manager to input commands to manage the annealing apparatus 100, a display for visualizing and displaying the operating status of the annealing apparatus 100, and the like. ing. Further, the process controller 60 causes each component of the annealing apparatus 100 to execute processing according to a control program for realizing various processes executed by the annealing apparatus 100 under the control of the process controller 60 and processing conditions. Is connected to a storage unit 62 that can store a program for storing the recipe. The recipe may be stored in a hard disk or semiconductor memory, or may be set at a predetermined position in the storage unit 62 while being stored in a portable storage medium such as a CDROM or DVD. Furthermore, you may make it transmit a recipe suitably from another apparatus via a dedicated line, for example. Then, if necessary, an arbitrary recipe is called from the storage unit 62 by an instruction from the user interface 61 and is executed by the process controller 60, so that a desired value in the annealing apparatus 100 is controlled under the control of the process controller 60. Processing is performed.

Next, the annealing operation in the annealing apparatus 100 as described above will be described.
First, the gate valve 25 is opened, the wafer W is loaded from the loading / unloading port 24, and placed on the support member 3. Thereafter, the gate valve 25 is closed to make the inside of the chamber 1 hermetically sealed, and the inside of the chamber 1 is evacuated through an exhaust port 23 by an exhaust device (not shown), and from a processing gas supply mechanism (not shown) through a processing gas introduction port 22. A predetermined processing gas, for example, argon gas or nitrogen gas is introduced into the chamber 1, and the pressure in the chamber 1 is maintained at a predetermined pressure in the range of 100 to 10,000 Pa, for example.

  In this state, the cooling medium supply mechanism 20 fills the housings 6a and 6b with a liquid cooling medium 21, for example, a fluorine-based inert liquid (trade name Fluorinert, Galden, etc.) and circulates the LED element 33 at 0 ° C. It cools to the following predetermined temperature, Preferably it is the temperature of -50 degrees C or less.

  Then, a predetermined current is supplied from the power supply unit 10 to the LED elements 33 of the heating sources 7a and 7b to light the LED elements 33. At this time, the LED element 33 is composed of a GaAs-based material, for example, GaAs or GaAsAl, and the light output of these materials is substantially proportional to the current. When the drive current is increased in a state in which the decrease in temperature is suppressed, for example, 100 mA or more, a large light output can be obtained, and the light output also increases due to the temperature drop itself due to cooling, so that a significantly large light output Can be obtained. Therefore, the wafer W can be rapidly heated at a heating rate of about 500 ° C./sec or higher, which is higher than before, and can be sufficiently applied to annealing that requires higher speed heating than before.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, in the above-described embodiment, the example in which the heat source having the LED elements is provided on both sides of the wafer that is the object to be processed has been described, but the heat source may be provided on either one. Moreover, although the example in which the LED element is directly immersed in the cooling medium for cooling is shown, the present invention is not limited to this. The object to be processed is not limited to the semiconductor wafer, and other objects such as a glass substrate for FPD can be targeted.

  The present invention is suitable for applications that require rapid heating, such as annealing after impurities are implanted.

1 is a cross-sectional view showing a schematic configuration of an annealing apparatus according to an embodiment of the present invention. Sectional drawing which expands and shows the heating source of the annealing apparatus of FIG. The schematic diagram which shows the arrangement | positioning state of the LED array in the heating source of the annealing apparatus of FIG. The graph which shows the transmittance | permeability curve of the fluorinate used as a cooling medium in the annealing apparatus of FIG. The figure which shows the radiation | emission (absorption) characteristic of silicon. The graph which shows the voltage-current characteristic of the LED element comprised by GaAs. The graph which shows the voltage-current characteristic of the LED element comprised by GaN. The figure which compares and shows the relationship of an electric current-light output in the case where GaAs and GaN are used as an LED element. The figure which compares and shows the relationship of temperature-light output in the case of using GaAs and GaN as an LED element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Chamber 1a, 1b; Opening part 2; Support pillar 3; Support member 5a, 5b; Light transmissive member 6a, 6b; Housing 7a, 7b; Heat source 10; Power supply part 20: Refrigerant supply mechanism 21; Processing gas inlet 23; Exhaust port 26; Temperature sensor 29a, 29b; Heat dissipation member 30a, 30b; Space 32; Support member 33; LED element 34; LED array 35; Electrode 36; Power supply member 37; Connection wire 60; 61; user interface 62; storage unit 100; annealing apparatus W ... semiconductor wafer (object to be processed)

Claims (10)

A processing container in which an object to be processed is stored;
A heating source having a plurality of LED elements for irradiating light to the object to be processed;
A power feeding unit that feeds power to the plurality of LED elements;
Cooling means for cooling the LED element;
A light transmissive member provided between the processing container and the heating source;
An annealing apparatus for annealing a target object by irradiating the target object with light emitted from the LED element,
An annealing apparatus, wherein the LED element is made of a GaAs-based material, and a high light output is obtained from the LED element by high current driving while cooling the LED element by the cooling means.   The annealing apparatus according to claim 1, wherein the heat source is provided on both sides of the processing container.   The cooling means includes a housing in which the heating source is accommodated, and a cooling medium supply mechanism that supplies a cooling medium that has an insulating property and transmits light emitted from the LED element into the housing. The annealing apparatus according to claim 1 or 2.   The annealing apparatus according to claim 3, wherein the cooling medium is a fluorine-based inert liquid.   The said cooling means cools the said LED element to 0 degrees C or less, and the said electric power feeding part sets the electric current sent through the said LED element to 100 mA or more, The any one of Claims 1-4 characterized by the above-mentioned. Annealing equipment. An annealing method for accommodating a target object in a processing container, feeding and lighting a plurality of LED elements, and annealing the target object with the light,
The LED element is made of GaAs material,
An annealing method comprising emitting light from the LED element with high light output by driving at a high current while cooling the LED element.   The annealing method according to claim 6, wherein the cooling is performed by directly contacting the LED element with a cooling medium having insulating properties and transmitting light emitted from the LED element.   The annealing method according to claim 7, wherein the cooling medium is a fluorine-based inert liquid.   The annealing method according to any one of claims 6 to 8, wherein the LED element is cooled to 0 ° C or less, and a current flowing through the LED element is set to 100 mA or more. A computer-readable storage medium storing a control program that runs on a computer,
A computer-readable storage medium, wherein when executed, the control program causes a computer to control an annealing apparatus so that the method of any one of claims 6 to 9 is performed.

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