JPH0922878A - Heat treatment furnace for substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat treatment furnace which can keep the uniformity of treatment temperature for every substrate by preheating a gas sufficiently which is supplied through a gas supply inlet to a furnace body, preventing the reduction of processing capacity by preparing a dummy substrate inside the furnace body, and suppressing the temperature drop in substrate due to gas. SOLUTION: A gas preheating member 20 which is heated by a heater 54 is prepared in a manner to partition a furnace body 10 into a gas leading part 22 and substrate housing part 24 therewith, and the member 20 is comprised of a plurality of flat plates 26, 28 and 30 which cross in a direction of axial center line of the furnace body and are placed in parallel and closely, further the gas leading part is connected with the substrate housing part through spaces among the flat plates as a passage for gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment furnace for subjecting a substrate such as a semiconductor wafer to various heat treatments such as annealing, oxidation and diffusion. The heat treatment furnace is, for example, an SOG (spin) on the surface of a semiconductor wafer. on glass
s) SOG formed on the wafer surface by applying material and heating
It is used, for example, when firing a film to densify it.

[0002]

2. Description of the Related Art As a heat treatment furnace for this type of substrate, a vertical heat treatment furnace as disclosed in, for example, JP-A-4-5827 is known. As shown in FIG. 4, this vertical heat treatment furnace has a cylindrical furnace body (furnace core tube) 50 having an upper end closed and an opening 52 formed at the lower end, as shown in FIG. Then, on the outside of the furnace body 50, a heater 54 is provided so as to surround the entire outer peripheral wall surface, in the illustrated example, a first heater 54a that is short in the vertical direction, a second heater 54b that is long in the vertical direction, and a short heater in the vertical direction. Third heater 54c
Are arranged. The main part of the furnace main body 50 is formed of a quartz glass material having infrared transparency, and the inside of the furnace main body 50 is heated through the wall surface of the furnace main body 50 by the heater 54. A gas supply port 56 for supplying a purge gas such as nitrogen gas or a reaction gas is provided at an upper end portion inside the furnace body 50. An exhaust pipe 58 is provided at the lower end of the furnace body 50. Then, a quartz boat 60, which holds a plurality of substrates W in parallel with each other in the vertical direction with a small gap, is inserted into the furnace body 50 through the opening 52 at the lower end of the furnace body 50. Further, the quartz boat 60 holding the substrate after the heat treatment is discharged to the outside of the furnace main body 50. On the lower end side of the quartz boat 60, a heat insulating support member 62 having a plurality of heat insulating plates parallel to each other and fixed in parallel to each other in a vertical direction is arranged on a column, and the heat insulating support member 62 is supported on a furnace port cap 64. ing. Then, by raising and lowering an elevator support arm (not shown), the quartz boat 60 supported on the furnace port cap 64 is raised and lowered, the quartz boat 60 is inserted into and removed from the furnace main body 50, and the quartz boat 60 is moved into the furnace main body 50. 5
It is configured so that the opening 52 at the lower end of the furnace body 50 is airtightly closed by the furnace port cap 64 when inserted into 0.

In a substrate heat treatment furnace having an example of the configuration shown in FIG. 4, gas is introduced from a gas supply port 56 at the tip of the furnace body 50 (upper end in a vertical furnace) to the substrate accommodating portion. When supplied, the temperature of the introduced gas is lower than the processing temperature of the substrate, so the substrate W heated by the heater 54 is cooled by the gas. In particular, the temperature of the substrate close to the gas introduction part (the substrate arranged in the upper part in the vertical furnace) becomes remarkable. As a result, the uniformity of the processing temperature is impaired even between the substrates that are simultaneously heat-treated.

Therefore, in order to raise the temperature of the gas introduced into the furnace main body 50, as shown in FIG. 4, a gas introduction pipe 66 is inserted into the inside of the furnace main body 50 from the vicinity of the lower end of the furnace main body 50. The gas introducing pipe 66 is extended along the inner wall surface of the furnace body 50 to the tip of the furnace body 50, or the gas introducing pipe is extended along the outer wall surface of the furnace body from the vicinity of the lower end to the vicinity of the upper end. The gas introducing pipe is provided so that the tip of the gas introducing pipe is communicated with the inside of the furnace body so that the gas introducing pipe is heated by the heater. Alternatively, a large number of dummy substrates are installed in parallel on the uppermost substrate to be processed held by the quartz boat to prevent the temperature of the substrate to be processed held on the upper side of the quartz boat from decreasing. The uniformity of the processing temperature is kept between the substrates to be processed.

[0005]

However, in the method of preheating the gas flowing in the gas introduction pipe by heating the gas introduction pipe by the heater to raise the temperature of the gas introduced from the gas supply port, the gas introduction pipe is used. Since the cross-sectional area of the channel is small, the gas passes through the gas introduction pipe in a short time, and the gas flows out from the gas supply port without a sufficient temperature increase. Further, since the temperature of the gas introducing pipe itself is lowered by the low temperature gas flowing in the gas introducing pipe, the gas is not preheated sufficiently by the gas introducing pipe, and the temperature of the gas cannot be sufficiently increased.

Further, in the method of installing a large number of dummy substrates on the uppermost substrate to be processed held by the quartz boat, if the total length of the furnace body does not change, only the dummy substrates are installed. The number of substrates accommodated decreases, and the processing capacity of the heat treatment furnace decreases.

The present invention has been made in view of the above circumstances, and it is possible to sufficiently preheat the gas supplied to the inside of the furnace body through the gas supply port. It is possible to suppress the temperature drop of the substrate due to the gas and maintain the uniformity of the process temperature among the substrates housed in the furnace body without installing the dummy substrate and lowering the processing capacity. An object of the present invention is to provide a heat treatment furnace for various substrates.

[0008]

The invention according to claim 1 is
A furnace main body having a sealable substrate loading / unloading port on one end side and a gas supply port disposed on the other end and accommodating a plurality of substrates in parallel with each other, and on the outside of the furnace main body In a substrate heat treatment furnace provided with a heating means for heating the inside of the furnace body, the inside of the furnace body is partitioned between a gas introduction section in which the gas supply port is arranged and a substrate accommodation section. In, a gas preheating member to be heated by the heating means is disposed, and the gas preheating member is composed of a plurality of flat plates which are parallel to and intersect each other in the axial direction of the furnace body. It is characterized in that the gas introducing portion and the substrate accommodating portion are communicated with each other by using a gap between the respective flat plates of the gas preheating member as a gas passage.

According to a second aspect of the present invention, the gas preheating member comprises a perforated flat plate having a through hole formed in a central portion and an outer peripheral edge portion integrally fixed to an inner peripheral wall surface of the furnace body, and the perforated flat plate. It is characterized by comprising a pair of flat plates fixed to both sides of the plate and provided with a constant interval in the entire circumferential direction between each outer peripheral edge and the inner peripheral wall surface of the furnace body.

[0010]

In the substrate heat treatment furnace according to the first aspect of the present invention, the gas introduced into the gas introduction part inside the furnace main body through the gas supply port bypasses through the gas passage formed in the gas preheating member. And is supplied to the substrate accommodation part. At this time, since the gas preheating member is heated by the heating means, while the gas passes through the gas passage formed in the gas preheating member, the gas is heated by heat transfer from the wall surface of the gas preheating member, and its temperature Rises. The gas preheating member is composed of a plurality of flat plates that intersect with and parallel to each other in the axial direction of the furnace body, and the gap between the flat plates serves as a gas passage. It will flow in the direction intersecting with the axial direction. Therefore, even if there is only a small gap between the flat plates, the cross-sectional area of the flow path that intersects the gas flow becomes relatively large, so the flow velocity of the gas becomes small, and the time during which the gas passes through the gas preheating member becomes small. Becomes longer. In addition, since there is only a small gap between the flat plates, the distance between the surface of each flat plate and the center of the gas flow in the axial direction of the furnace body (1/2 of the gap between the flat plates) Becomes smaller, which facilitates the transfer of heat from each flat plate to the gas.
Therefore, when the gas passes through the gas preheating member, heat exchange between them is sufficiently performed, and the gas is
It is supplied to the substrate accommodating portion in a state where it is sufficiently preheated and the temperature is sufficiently raised. As a result, the temperature decrease of the substrate due to the gas is suppressed.

In the heat treatment furnace according to the second aspect of the present invention, the gas introduced into the gas introducing portion passes through the gap formed by one surface of the perforated flat plate of the gas preheating member and the flat plate surface facing the flat plate surface. , Radially from the inner wall surface side of the furnace body toward the center of the furnace body, passing through the through hole in the center of the perforated flat plate,
The gas flows in the radial direction from the central portion of the furnace body toward the inner peripheral wall surface of the furnace body through a gap formed by the other surface of the perforated disk and the flat plate surface facing it. During this period, the gas is sufficiently preheated and its temperature rises, and then the gas is supplied to the substrate housing portion in that state.

[0012]

Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical cross-sectional view showing an embodiment of the present invention and showing a schematic structure of a substrate heat treatment furnace (a vertical heat treatment furnace in this example). It should be noted that, in FIG. 1, members given the same reference numerals as those used in FIG. 4 are the same members as those described with reference to FIG. 4, and the description thereof will be omitted.

As in the heat treatment furnace shown in FIG. 4, the furnace body 10 of this heat treatment furnace has a main part formed of a quartz glass material having infrared transparency, and a quartz boat holding a large number of substrates W. An opening 12 for inserting and discharging 60 is formed at the lower end side, and an exhaust pipe 14 is provided at the lower end portion. On the other hand, a gas introduction pipe 16 is provided at the upper end of the furnace body 10, and the gas supply port 1 is provided at the upper end inside the furnace body 10.
8 are provided.

In this heat treatment furnace, a gas preheating member 20 is arranged near the upper end inside the furnace body 10, and this gas preheating member 20 introduces gas through the gas supply port 18. The part 22 and the substrate housing part 24, which is held by the quartz boat 60 and houses a large number of substrates W, are partitioned. As shown in the enlarged sectional view of the upper portion of the furnace main body 10 in FIG. 2, the gas preheating member 20 is different from that of FIG. 1 in that the shape of the furnace main body 10 and the shape of the gas preheating member 20 are slightly different. The basic configuration is the same.), And a perforated disc 26 having a through hole 28 formed in the central portion thereof, and an upper disc 30 and a lower disc 3 fixed to both sides of the perforated disc 26, respectively.
And 2. These three discs 26, 3
0 and 32 are formed of, for example, quartz glass, and each has a circular shape. Also, the three disks 26, 3
Nos. 0 and 32 are held in parallel so as to intersect each other at right angles to the axial direction of the furnace body 10 and to be parallel to each other. The disk 32 is about 0.5 to several mm, for example, 2 mm
They face each other with a certain gap. The outer peripheral edge of the perforated disc 26 is integrally fixed to the inner peripheral wall surface of the furnace body 10 by integral molding or welding, and the gas preheating member 20 is supported on the inner peripheral wall surface of the furnace body 10. There is. On the other hand, the upper disc 30 and the lower disc 32 are each formed smaller than the perforated disc 26, and between the outer peripheral edge of each disc 30, 32 and the inner peripheral wall surface of the furnace body 10, A constant interval is provided in the circumferential direction.

In this heat treatment furnace, a large number of substrates W held in the quartz boat 60 are loaded into the furnace body 10 through the opening 12 at the lower end of the furnace body 10, and the opening 1 at the lower end of the furnace body 10 is loaded.
2 is airtightly closed by the furnace port cap 64, and in this state, the inside of the furnace body 10 is heated by the heater 54, and gas is introduced into the furnace body 10 through the gas supply port 18.
For example, the substrate is heat-treated by supplying wet oxygen gas. At this time, the gas preheating member 20 is also heated by the heater 54, and the temperature is raised to near the processing temperature of the substrate. In addition, the gas introduced from the gas supply port 18 to the gas introduction part 22 is discharged from between the outer peripheral edge of the upper disc 30 of the gas preheating member 20 and the inner peripheral wall surface of the furnace body 10 to the upper face of the perforated disc 26. After flowing into the gap between the lower surface of the upper disc 30 and the inside of the gap in the radial direction from the entire circumferential direction of the furnace body 10 toward the central portion, a through hole in the central portion of the perforated disc 26 is formed. Through a gap 28 between the lower surface of the perforated circular plate 26 and the upper surface of the lower circular plate 32, and flowed in the radial direction from the center of the furnace body 10 toward the entire circumference in the gap. Rear bottom disc 32
Flows into the substrate housing portion 24 from between the outer peripheral edge of and the inner peripheral wall surface of the furnace body 10. As described above, the gas passes from the gas introduction part 22 to the substrate housing part 24 through the narrow gap of the gas preheating member 20, and is relatively low in the direction orthogonal to the axial direction of the furnace body 10, particularly the gas preheating member. Since the gas flows at a low speed on the outer peripheral side of 20, the gas is efficiently heated from each of the disks 26, 30, 32 during this time, and the temperature rises. Then, the gas comes into contact with the substrate W in a state where the temperature has risen sufficiently, so that the temperature decrease of the substrate W due to the gas is suppressed.

Further, since the three flat plates 26, 30, 32 intersect each other at right angles to the axial direction of the furnace body 10 and are held in parallel so as to be parallel to each other, The distance between the outer peripheral edge of the disk 32 and the inner peripheral wall surface of the furnace body 10 is the same in the positional relationship in the axial direction of the furnace body 10 over the entire circumference. The gas flowing out from between the inner wall surface and the furnace main body 1
A uniform flow is obtained in the direction of the axis of 0. This makes it possible to achieve more uniform processing. Further, in this way, the flat plates 26, 30, 32 intersect so as to be orthogonal to the axial direction of the furnace body 10, and are held in parallel so as to be parallel to each other. It is also advantageous in terms of space, and the accommodation capacity of the substrate can be improved.

FIG. 3 is a partially enlarged sectional view showing a different example of the gas preheating member. The gas preheating member 34 is provided with a central disc 36 having a through hole 38 formed in the central portion thereof and a plurality of through holes disposed in the upper and lower sides of the central disc 36, respectively, in the circumferential direction near the outer peripheral edge. An upper disc 40 and a lower disc 44 are formed by equally arranging 42 and 46. Similar to the gas preheating member 20 shown in FIGS. 1 and 2, each of the disks 36, 40, 44 is made of quartz glass in a circular shape, and is orthogonal to the axial direction of the furnace body 10. A small gap parallel to each other,
For example, they are arranged with a gap of about 0.5 to several mm. Each of the disks 36, 40, 44 is integrally fixed by welding to the inner peripheral wall surface of the furnace body 10 at the entire outer peripheral edge portion thereof.

In the gas preheating member 34 shown in FIG. 3, the gas introduced from the gas supply port 18 of the furnace body 10 to the gas introduction portion passes through a plurality of through holes 42 near the outer peripheral edge of the upper disc 40. After passing through the gap between the lower surface of the upper circular plate 40 and the upper surface of the central circular plate 36 and flowing in the gap from the entire circumferential direction of the furnace body 10 toward the central portion, the central circle It flows through the through hole 38 in the central portion of the plate 36 into the gap between the lower surface of the central disc 36 and the upper surface of the lower disc 44, and within the gap from the central portion of the furnace body 10 to the entire circumferential direction. After flowing in the radial direction toward the substrate accommodating portion 24, it passes through a plurality of through holes 46 near the outer peripheral edge of the lower disk 44. And
As described above, while the gas flows while bypassing the inside of the gas preheating section 34, the gas is preheated by each of the disks 36, 40 and 44.

In each of the above embodiments, the gas preheating member is composed of three discs. However, the disc having a through hole in the center and one of the discs is provided on one side. The gas preheating member may be constituted by two discs including the disc arranged in the above, or the gas preheating member may be constituted by combining four or more discs. Further, the shape of the gas preheating member is not limited to that of the above-mentioned embodiment, and is composed of a plurality of flat plates which are orthogonal to the axial center direction of the furnace body and are parallel to and close to each other, and the gas flow is circular. Any shape may be used as long as it is uniform in the circumferential direction.

Further, in the above embodiment, the gas introducing pipe 16 is provided at the upper end of the furnace body 10 and the gas supply port 18 is provided in the furnace body 10.
Although it is arranged at the upper end of the inside, the gas introduction pipe is extended along the outer wall surface of the furnace body from near the lower end of the furnace body to near the upper end, and the tip of the gas introduction pipe is placed at the upper end of the furnace body. It should be connected to the inside of the furnace body in the vicinity, or
As shown in, insert the gas introduction pipe into the furnace body from the vicinity of the lower end of the furnace body, extend the gas introduction pipe upward along the inner wall surface of the furnace body, and penetrate the gas preheating member. You may make it arrange | position the front-end | tip part of a gas introduction pipe. This is more effective because the gas introduction pipe is heated by the heater and the temperature of the gas introduced into the gas introduction portion inside the furnace body rises even a little.

Further, in the above embodiment, the gas preheating member 20 is used.
The flat plates 26, 30, and 32 constituting the above are crossed so as to be orthogonal to the axial direction of the furnace body 10, and are held in parallel so as to be parallel to each other. However, the intersecting angle between each flat plate and the axial direction of the furnace body 10 and the positional relationship between the flat plates can be appropriately set as long as the accommodation capacity of the substrate and the uniformity of the gas flow are not impaired.

[0023]

When the substrate heat treatment furnace according to the first aspect of the present invention is used, the gas supplied into the furnace body through the gas supply port is sufficiently preheated and the temperature of the substrate is increased. Since they come into contact with each other, the temperature drop of the substrate due to the gas is suppressed, and therefore, the uniformity of the processing temperature among the plurality of substrates housed in the furnace body is maintained, and the heat treatment quality of the substrate is improved. Uniformity is achieved. Further, since it is not necessary to install a dummy substrate inside the furnace body, the processing capacity is not lowered.

In the structure of the invention according to claim 2, the gas introduced into the gas introducing portion is provided with a gap between the one surface of the perforated circular plate of the gas preheating member and the flat plate surface opposite thereto and the perforated circular circle. The above effect is reliably exhibited because the temperature is increased by being sufficiently preheated while sequentially flowing through the gap between the other surface of the plate and the flat plate surface facing it.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a schematic configuration of a substrate heat treatment furnace according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the upper part of the furnace body showing an example of the gas preheating member in the heat treatment furnace for substrates according to the present invention.

FIG. 3 is a partially enlarged sectional view showing another configuration example of the gas preheating member.

FIG. 4 is a schematic vertical sectional view showing an example of the configuration of a conventional substrate heat treatment furnace.

[Explanation of symbols]

 10 Furnace Main Body 12 Opening at Lower End of Furnace Main Body 16 Gas Introducing Pipe 18 Gas Supply Port 20, 34 Gas Preheating Member 22 Gas Introducing Section 24 Substrate Accommodating Section 26 Perforated Disc 28 Perforated Disc 30, 32 Disc 36, 40, 44 Disc 38, 42, 46 Disc through hole 54 Heater 60 Quartz boat 64 Furnace cap W Substrate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 21/324 H01L 21/324 D

Claims (2)

[Claims] 1. A furnace body having a sealable substrate loading / unloading port at one end and a gas supply port at the other end, and containing a plurality of substrates in parallel with each other. In a substrate heat treatment furnace provided with a heating means arranged outside the furnace body to heat the inside of the furnace body, a gas introduction part and a substrate housing part in which the gas supply port is arranged, inside the furnace body. A gas preheating member, which is composed of a plurality of flat plates that intersect with each other in the axial direction of the furnace main body and are parallel to each other and close to each other, is heated by the heating means so as to partition the space A heat treatment furnace for a substrate, characterized in that the gap between each of the flat plates of the preheating member is used as a gas passage to communicate the gas introducing portion with the substrate housing portion. 2. A gas preheating member, a perforated flat plate having a through hole formed at a central portion and an outer peripheral edge portion integrally fixed to an inner peripheral wall surface of a furnace body, and fixed to both sides of the perforated flat plate, respectively. 2. The heat treatment furnace for a substrate according to claim 1, comprising a pair of flat plates each having a constant interval in the entire circumferential direction between the outer peripheral edge and the inner peripheral wall surface of the furnace body.