JP3596312B2 - Heat treatment equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heat treatment apparatus and a heat treatment method used for manufacturing a semiconductor device and the like.
[0002]
[Prior art]
In the manufacture of semiconductor devices, various heat treatments such as diffusion of impurities, densification of thin films by oxidation or heating, baking of spin-on glass (hereinafter abbreviated as SOG), and baking of resist are performed in the process of manufacturing semiconductor devices. These heat treatments are usually performed by a heat treatment apparatus (hereinafter, referred to as a batch) in which a large number of substrates are inserted into a heat-resistant tube made of quartz or the like around which a heater as a heating source is placed to perform heat treatment. Furnace), a heat treatment apparatus (hereinafter, referred to as a baking furnace) that carries a heat treatment by transporting a substrate loaded on a belt conveyor or the like under a heating source such as a resistance heating means, or a heating source such as an infrared lamp. For example, a heat treatment apparatus (hereinafter, referred to as a single-wafer furnace) for performing a heat treatment by setting one substrate to be processed facing the substrate is used.
[0003]
[Problems to be solved by the invention]
2. Description of the Related Art In order to improve the productivity of semiconductor devices, the size of a semiconductor substrate is increased (hereinafter, referred to as an increase in diameter) to increase the number of semiconductor elements that can be obtained from one semiconductor substrate. However, in a conventional heat treatment apparatus, as the diameter of a semiconductor substrate as a substrate to be processed increases, temperature variation in the surface of the substrate to be processed becomes an important problem.
[0004]
In a batch furnace, since the substrate to be processed is placed inside the quartz tube in a position perpendicular to the heater outside the quartz tube, the temperature rise in the surface of the substrate Take the form that heat is transmitted to the part. For this reason, since the distance of heat conduction is increased by increasing the diameter of the substrate to be processed, the temperature difference between the peripheral portion and the central portion of the substrate to be processed increases, and the characteristics of the semiconductor elements formed in the substrate to be processed are affected. There is a problem that it differs depending on the position in the processing substrate surface. Further, in a baking furnace or a single-wafer furnace, heat treatment is performed in such a manner that the heat source and the substrate to be processed face each other, so that the in-plane temperature of the heat source varies and the heat source faces the substrate to be processed. Variations in the distance directly result in temperature variations in the surface of the substrate to be processed.
[0005]
When measures are taken to increase the size of the heating source in accordance with the increase in the diameter of the substrate to be processed, a very large heating source is required as compared with the substrate to be processed in order to secure a uniform heating length of the heating source. For this reason, the heat treatment apparatus becomes extremely large, and becomes difficult to be put to practical use. In addition, in a baking furnace or a single-wafer furnace, the size of the heating source increases due to an increase in the size of the heating source, and the characteristics of the semiconductor element formed in the substrate to be processed differ depending on the position in the surface of the substrate. The problem becomes noticeable.
[0006]
Further, heat treatment for densification of a thin film formed on a substrate to be processed, baking of a spin-on-glass (hereinafter, referred to as SOG) film, or baking of a photoresist (hereinafter, referred to as resist) film is performed. When applied, moisture absorption moisture and constituent materials of the film are released from the thin film, the SOG film, or the resist film in a gaseous state (hereinafter, referred to as outgas). The outgassing amount increases as the diameter of the substrate to be processed increases. When the substrate to be processed has a small diameter, the space formed between the surface of the substrate to be processed and the heating source is small, and the outgas is quickly carried away from this space by convection. However, when the substrate to be processed has a large diameter, the space between the surface of the substrate to be processed and the heating source is widened. Affects the substrate to be processed. The effect is a change in film quality of the thin film or generation of particles on the substrate to be processed, which causes a problem of lowering the yield of the semiconductor element to be manufactured.
[0007]
The first object of the present invention is to provide a heat treatment apparatus and a heat treatment method that realize heat treatment with good uniformity in heat treatment of a large-diameter substrate to be processed, and reduce the influence of outgas on the substrate to be processed. A second object is to provide a heat treatment apparatus and a heat treatment method that can perform the heat treatment.
[0015]
[Means for Solving the Problems]
To achieve the second object, the thermal processing apparatus Ru engaged to the present invention includes a heat source consisting of a plurality of heating elements, the lower the heat source in a heat treatment device having a region in which the processing substrate passes A configuration in which the distance between each of the heating elements and the region through which the substrate to be processed passes increases or decreases stepwise, or a configuration in which the heating elements other than the heating elements at both ends of the heating elements and the processing target substrate The minimum distance to the region through which the substrate passes, and the distance between each heating member and the region through which the substrate to be processed increases toward the heating members at both ends, and the inert gas is located at the center of the heat treatment apparatus. A gas inlet for introducing the inert gas, and the flow of the inert gas is created from the central portion to the both ends. Further, according to the heat treatment apparatus of this, by arranging so as to open toward a plurality of heating elements to the outside, conveying surface of the substrate to be processed and the outgassing heat source generated from the substrate to be treated by heating and in It can be quickly discharged from the space to be formed, and the influence of the outgas on the substrate to be processed can be eliminated.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Reference Example )
Hereinafter, a first reference example of the heat treatment apparatus of the present invention will be described with reference to the drawings.
[0017]
1A, 1B, and 1C show a perspective view of a heat treatment apparatus according to the present embodiment, and a rear view and a top view of the heat treatment apparatus as viewed from a conveyor belt. In FIG. 1, reference numeral 11 denotes a substrate to be processed, 12 denotes a heating source, 13 denotes a transport belt, 14 denotes a rotation direction of the substrate to be processed, and 14a denotes a transport direction of the transport belt. FIG. 1B shows the back surface of the transport belt 13. The loading section 13 a of the substrate 11 has a rotation gear 15 at the center, and is connected to the transport belt 13 via a bearing 16. The rotation gear 15 is in mesh with the guide gear 17.
[0018]
Next, the heat treatment method according to the present embodiment will be described with reference to FIG. The substrate 11 to be processed is loaded on the loading portion 13a of the transport belt 13, and the transport belt 13 is transported in the transport direction 14a. The rotation gear 15 attached to the back surface of the loading unit 13 a rotates the loading unit 13 a by the guide gear 17 by the movement of the transport belt 13. Due to this movement, the substrate 11 to be processed is conveyed under the heating source 12 while rotating.
[0019]
According to the present embodiment, the substrate to be processed passes while rotating even under a heating source having poor heat uniformity, thereby dispersing temperature variations in the surface of the substrate to be processed during the heat treatment, and , A uniform heat treatment can be realized.
[0020]
In addition, the process of heating the substrate to be processed by the firing furnace is performed by heating the region of the substrate to be processed entering the firing furnace by radiant heat from a heating source, and by heating the region of the substrate to be processed heated by the radiant heat. This is done by heat propagation to the heating zone. The process of heating the substrate to be processed according to the present embodiment will be described with reference to the top view of the heat treatment apparatus shown in FIG. The region 11a is a region of the substrate to be heated under the heating source 12, the heated region 11b is a region already heated under the heating source 12 and deviated from under the heating source 12 by rotation, and an unheated region 11c. Indicates an unheated region of the substrate to be processed. Compared to a conventional heat treatment apparatus in which the substrate 11 is not rotated, the heat treatment apparatus of the present embodiment increases the heated area 11b, which indicates that the substrate to be processed is heated more quickly. Furthermore, compared to the heat treatment by the conventional heat treatment apparatus, the heated region is enlarged, so that the heat conduction 11d from the heated region to the unheated region 11c is performed quickly.
[0021]
In the heat treatment apparatus according to the present embodiment, even when the heating source 12 is shorter than the diameter of the substrate 11 as shown in FIG. 1C, uniform heating can be applied to the substrate 11. Can be reduced in size.
[0022]
A heat treatment method for a semiconductor device using the heat treatment apparatus will be described.
In photolithography, a substrate to which a resist film is applied is subjected to a heat treatment at about 120 ° C. to cure the resist film except for an organic solvent contained in the resist material (hereinafter, referred to as pre-bake), and to expose and develop. Thereafter, the swollen resist pattern is subjected to a heat treatment at about 120 ° C. to cure the resist pattern (hereinafter, referred to as post bake).
[0023]
On the other hand, variations in the temperature of the heating source cause variations in the curing of the resist film and variations in the curing of the resist pattern, causing an increase in the dimensional variation of the resist pattern on the substrate to be processed, and deteriorating the characteristics of the semiconductor device to be subsequently manufactured on the substrate to be processed. Cause.
[0024]
In the heat treatment method according to the present embodiment, it is possible to uniformly heat a substrate to be processed having a resist film or a resist pattern, and to use a heat treatment apparatus with a heating source shorter than the diameter of the substrate to be processed to reduce outgas. Since it can be discharged quickly, it is possible to form a resist film without curing unevenness and to form a resist pattern with good dimensional accuracy.
[0025]
(Second reference example )
Next, a description will be given of a second exemplary embodiment of the present invention.
[0026]
3A and 3B are a side view and a top view of a heat treatment apparatus for a firing furnace according to the present embodiment, and FIG. 4 is a temperature setting diagram of a heating source. In FIG. 3, 31 is a substrate to be processed, 32a, 32b, 32c, 32d, and 32e are heating elements that can be independently controlled in temperature, 33 is a substrate holder, 34 is a rotation direction of the substrate to be processed by a rotation mechanism, and 34a is This shows the transport direction of the transport belt.
[0027]
A heat treatment method using the heat treatment apparatus will be described. A deposition temperature of 450 ° C. by an atmospheric pressure chemical vapor deposition (hereinafter, referred to as an atmospheric pressure CVD) method using a SiH ₄ gas and an O ₂ gas as an insulating film formed on a silicon semiconductor substrate in which a transistor region is formed. SiO ₂ film in form are used. However, the SiO ₂ film formed by the normal pressure CVD method lacks denseness, and has a processing problem that etching resistance with a hydrofluoric acid aqueous solution for subsequent fabrication of a semiconductor element is weak. For this purpose, a process of heating the substrate on which the SiO ₂ film is formed to about 700 ° C. to improve the compactness (hereinafter, referred to as a compaction process) is usually performed.
[0028]
On the other hand, in the conventional heat treatment apparatus, since the uniformity of the heat source is reduced due to the increase in the size of the heat source, a difference is caused in the densification in the surface of the substrate to be processed, which causes unevenness in etching at the time of etching, resulting in a semiconductor device yield. Had been lowered.
[0029]
In addition, when a large-diameter substrate to be processed is subjected to a high-temperature heat treatment at 700 ° C. by using a conventional heat treatment apparatus without rotating, a state in which a heated region and an unheated region in the surface of the substrate to be processed are separated for a long time. Because of the continuation, a large thermal stress occurs in the surface of the substrate to be processed, causing cracks in the substrate to be processed.
[0030]
Using the heat treatment apparatus of the present embodiment in which the heating bodies 32a, 32b, 32c, 32d, and 32e were set to the temperatures shown in FIG. 4, the densification treatment of the SiO ₂ film formed by the normal pressure CVD method was performed. First, the first substrate 31 to be processed is transported from a room temperature state to below a heating body 32a set at 500 ° C. Subsequently, the substrate 31 to be processed is heated to 700 ° C. by the heating body 32b and subjected to a heat treatment of 750 ° C. by the heating body 32c, and then sequentially passes through the heating body 32d set at 700 ° C. and the heating body 32e set at 500 ° C. And carried out. At this time, since the substrate to be processed is conveyed while rotating, the temperature in the surface of the substrate to be processed is quickly and uniformly increased. In addition, since the temperature of the substrate to be processed is raised and lowered step by step, heat treatment without uneven etching and cracking of the substrate to be processed can be performed.
[0031]
Note that, in the present embodiment, the temperature settings of the plurality of heating elements are independently performed, but the same is performed by setting each heating element to the same temperature and changing the distance between each heating element and the substrate to be processed. The effect of can also be obtained.
[0032]
(Third reference example )
Next, a description will be given of a third exemplary embodiment of the present invention.
[0033]
FIG. 5 shows a side view of the heat treatment apparatus used in the present embodiment. In FIG. 5, reference numeral 51 denotes a substrate to be processed, 52 denotes a heating source, 53 denotes a conveyor belt, 55 denotes outgas from the substrate to be processed, and 55a denotes a flow of outgas out of the heat treatment apparatus.
[0034]
As shown in FIG. 5, the heating surface of the heating source 52 and the conveying surface of the conveying belt 53 are inclined and non-parallel. Since the outgas 55 discharged from the substrate 51 is discharged by convection outside the heat treatment apparatus along the slope, the outgas 55 does not stay between the heating source 52 and the transport belt 53.
[0035]
Note that when the substrate to be processed is rotated by the rotating mechanism, temperature variations in the surface of the substrate to be processed can be reduced at the same time.
[0036]
(Fourth reference example )
Next, a fourth reference example of the present invention will be described.
[0037]
FIGS. 6A and 6B show a side view and a top view of the heat treatment apparatus for a single-wafer furnace in the present embodiment. 6, reference numeral 61 denotes a substrate to be processed, 62 denotes a heating source, 62a denotes a center point of the heating source, 63 denotes a substrate holder, 63a denotes a rotation axis of the substrate holder, and a rotation axis 63a of the substrate holder denotes a center point of the heating source. The positional relationship is set to be eccentric with respect to 62a.
[0038]
Normally, the temperature of the heating source 62 of a single-wafer furnace tends to be high at the center and lower toward the periphery. This is due to the fact that heat propagation is concentrated at the center of the heat source and that the gas heated during the heat treatment flows to the outer periphery of the heat source, resulting in a decrease in the temperature of the outer periphery. For this purpose, conventional heat treatment is performed without rotating the substrate to be processed in opposition to a heat source having poor heat uniformity, or by rotating the substrate to be processed in a state where the center of the heat source and the center of the substrate are aligned. When a conventional heat treatment to be performed is performed on a substrate to be processed, a temperature variation in a form in which a temperature distribution of a heating source is projected is caused in a surface of the substrate to be processed.
[0039]
On the other hand, in the heat treatment apparatus according to the present embodiment, by rotating the substrate to be processed in such a manner that the center of the heating source and the center of the substrate to be processed are eccentric, the substrate to be processed facing the high-temperature portion or the low-temperature portion of the heating source is rotated. The position is changed, and the temperature variation in the surface of the substrate to be processed is reduced.
[0040]
FIG. 7 is a side view showing another heat treatment apparatus according to the fourth embodiment of the present invention. In FIG. 7, the rotation shaft 63a of the substrate holder 63 faces the center point 62a of the heating source 62 and has substantially the same positional relationship. Since the center point 61a of the substrate 61 to be processed is installed in an eccentric relationship with the rotating shaft 63a, the substrate 61 to be processed is eccentrically rotated with respect to the heating source 62. This reduces temperature variations in the surface of the substrate to be processed.
[0041]
Note that a mechanism for rotating the substrate to be processed may be provided in the heat treatment apparatus of FIG. 7 to cause the substrate to be processed to revolve on its own axis.
[0042]
(Fifth reference example )
Next, a fifth reference example of the present invention will be described.
[0043]
FIG. 8 is a side view of a heat treatment apparatus for a single-wafer furnace according to the present embodiment. In FIG. 8, reference numeral 81 denotes a substrate to be processed, 82 denotes a heating source, 82a denotes an infrared lamp for heating, 83 denotes a substrate holder, 84 denotes an opening provided in the heating source 82, and 85a and 85b denote portions from the substrate 81 to be processed. 4 shows the flow of outgas.
[0044]
In the conventional heat treatment apparatus, the outgas released from the target substrate 81 stays between the target substrate 81 and the heating source 82. However, by providing the opening 84, the outgas can be quickly discharged to the outside of the heat treatment apparatus. Became possible.
[0045]
A heat treatment method for a semiconductor device using the heat treatment apparatus will be described.
Normally, a flat insulating film is formed on a substrate to be processed, which is a semiconductor substrate having a gate electrode formed thereon, by a normal pressure CVD method using a SiH ₄ gas, an O ₂ gas, a B ₂ H ₆ gas, and a PH ₃ gas. _A borophosphosilicate glass film (hereinafter, referred to as a BPSG film) containing ₂ O ₃ and P ₂ O ₅ is formed, and subsequently subjected to a heat treatment at about 850 ° C. to soften the glass (hereinafter, referred to as a glass flow). ).
[0046]
However, since the BPSG film has a high hygroscopicity, phosphate hydrate and boric acid hydrate are released from the BPSG film as outgas together with water when glass flow is performed. In a conventional heat treatment apparatus, a large amount of outgas released stays in a space formed between a substrate to be processed and a heating source and reacts with the BPSG film to generate a BPO ₄ compound precipitate. Since this precipitate is extremely difficult to be etched and has a protruding shape, a failure occurs in the subsequent formation of a fine pattern or etching of the BPSG film, and the yield of semiconductor elements formed on the substrate to be processed is reduced.
[0047]
By the way, when the glass flow of the BPSG film is performed using the heat treatment apparatus according to the present embodiment, the outgas from the target substrate 81 flows through the flow 85 a from the end of the heating source 82 and the opening 84 provided in the heating source 82. It becomes stream 85b and is quickly discharged without stagnation. For this reason, the glass flow of the BPSG film without any precipitate was able to be performed, and a decrease in the yield of the semiconductor element formed on the substrate to be processed could be prevented.
[0048]
( 1st Embodiment)
Next, a first embodiment of the present invention will be described.
[0049]
FIG. 9 shows a side view of the heat treatment apparatus in the present embodiment. 9, reference numeral 91 denotes a substrate to be processed, 92 denotes a heating source, 92a, 92b and 92c denote heating bodies, 93 denotes a conveyor belt, 94 denotes a gas inlet, 94a denotes a flow of a gas to be introduced, and 95 denotes a flow from the substrate to be processed. Outgas 95a indicates the flow of the outgas outside the heat treatment apparatus.
[0050]
The heating bodies 92a, 92b, and 92c are set so that the distance from the center of the heating source 92 to the outside of the heating source 92 to the transport belt 93 increases. With this setting, the outgas 95 from the substrate to be processed is discharged to the outside of the heat treatment apparatus by the inclination created by the heating bodies 92a, 92b, and 92c. Further, in the present embodiment, the effect of accelerating the outgas flow 95a out of the heat treatment apparatus is obtained by introducing an inert gas into the heat treatment apparatus from the gas inlet 94 at the center of the heat treatment apparatus.
[0051]
A heat treatment method for a semiconductor device using the heat treatment apparatus will be described.
Usually, an SOG film used for an insulating film of a semiconductor device is formed by applying an SOG material containing a silicon compound such as silanol in an organic solvent to a substrate to be processed and baking it at about 400 ° C. However, since the SOG material contains an organic solvent, a large amount of outgas is generated during the heat treatment. When a large-diameter substrate to be heated is subjected to heat treatment by a conventional heat treatment apparatus, non-uniform outgassing occurs near the center of the space between the heat treatment substrate and the heat source. When a large amount of outgas containing an organic solvent as a main component comes into contact with the SOG film, the firing effect of the SOG film is reduced, and the hardness and denseness of the SOG film are reduced. For this reason, in the above-described conventional heat treatment apparatus, the outgas that has non-uniformly accumulated forms an SOG film having inhomogeneity in hardness and denseness on the surface of the substrate to be processed, thereby lowering the yield of semiconductor elements to be manufactured subsequently. . In the heat treatment apparatus of the present embodiment, since the outgas is quickly discharged, the heat treatment method using this heat treatment apparatus can form a uniform SOG film, and the yield of subsequently formed semiconductor elements is also good.
[0052]
In the present embodiment, the distance between the heating member 92a at the center of the heat treatment apparatus and the conveyor belt 93 is set to be the minimum. However, in order to discharge heated outgas, each heating member is required. Any configuration may be used as long as the distance between the belt and the conveyor belt increases or decreases stepwise or with a slope.
[0059]
【The invention's effect】
According to the heat treatment apparatus of the present invention , a plurality of heating elements are arranged at an inclination opening toward the outside, and a heat treatment apparatus having a structure in which an inert gas is introduced into a central portion is used to heat-treat outgas from a substrate to be processed. Since the gas can be quickly discharged from the inside of the apparatus, deterioration of the semiconductor device caused by stagnation of outgas around the substrate to be processed can be prevented.
[Brief description of the drawings]
[1] This first aspect of the heat treatment apparatus according to the reference example diagram Figure 2 of the heat treatment apparatus according to a first exemplary embodiment of the present invention partially enlarged top view Figure 3 a second of the present invention configuration diagram of a heat treatment apparatus according to a third reference example of FIG. 5 shows the present invention showing the temperature setting of the heat treatment apparatus according to a second reference example of the block diagram FIG. 4 the invention of a heat treatment apparatus according to the reference example FIG. 6 is a configuration diagram of a heat treatment apparatus according to a fourth reference example of the present invention; FIG. 7 is a configuration diagram of a heat treatment apparatus according to a fourth other reference example of the present invention; FIG. FIG. 9 is a configuration diagram of a heat treatment apparatus according to a reference example . FIG. 9 is a configuration diagram of a heat treatment apparatus according to the first embodiment of the present invention.
11 substrate to be processed 12 heating source 13 transport belt 14 rotation direction 14a of substrate to be processed transport direction of transport belt

Claims (2)

In a heat treatment apparatus having a heating source including a plurality of heating elements and an area through which the substrate passes below the heating source, the distance between each of the heating elements and the area through which the substrate passes increases step by step. A heat treatment apparatus , wherein a gas inlet for introducing an inert gas is provided at a central portion of the heat treatment device, and the flow of the inert gas is generated from the central portion to the both ends . The distance between each heating element and the area where the substrate to be processed passes in the heat treatment apparatus having a heating source composed of a plurality of heating elements and an area where the substrate to be processed passes under the same heating source, the heating at both ends. The distance between the heating body other than the body and the area through which the substrate to be processed passes is the minimum, and the distance between each heating body and the area through which the substrate to be processed passes increases toward the heating bodies at both ends. A heat inlet provided with a gas inlet for introducing an inert gas at a central portion of the heat treating device , wherein the inert gas flows from the central portion to the both ends .

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