JP3203536B2 - Vertical heat treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical heat treatment apparatus.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing process, a CVD apparatus has been used for laminating a thin film or an oxide film on a surface of a semiconductor wafer (hereinafter referred to as a wafer) to be processed or for diffusing impurities. An oxide film forming device or a diffusion device is used. And as one of this type of apparatus, wafers are arranged and held in multiple stages in the vertical direction,
A vertical heat treatment apparatus is used which is housed in a process tube (reaction vessel) heated at a high temperature and is processed by a processing gas introduced into a processing chamber.

As shown in FIG. 11, the vertical heat treatment apparatus has a cylindrical outer container 2 having a bottom and made of quartz glass, and a quartz glass tube placed in the outer container 2 with a gap 4 therebetween. A heat insulating vessel having a reaction vessel 1 composed of an internal vessel 30 and a vertically arranged reaction vessel 1 with an opening facing downward and having a heater 5 as a heating means on its inner wall surface. A main part is constituted by a furnace main body 6, a wafer boat 7 made of quartz for holding the wafers W in multiple stages in the vertical direction, and an elevating mechanism 8 for elevating the wafer boat 7. A wafer boat 7 and an elevating mechanism 8 are provided, and carry-in / out means 9 for carrying or carrying out the wafer W stored in the wafer carrier C carried by the carrier carrying means (not shown) to / from the wafer boat 7 is provided. Have been.

In the above vertical heat treatment apparatus, the inner container 3
An inlet 11 of the processing gas introduction pipe 10 is provided in the lower opening of the cylinder 0, and an exhaust port 13 of a processing gas exhaust pipe 12 is provided below the outer container 2. Also, the wafer boat 7
Is provided with a lid 15 via a heat retaining tube 14 below a holding portion 7a for holding the wafer W in multiple stages.
Is configured so that the inside of the reaction vessel 1 is sealed by closing the opening of the reaction vessel 1. Thus, a predetermined processing gas can be supplied into the reaction vessel 1 from the processing gas introduction pipe 10 while the inside of the reaction vessel 1 is evacuated from the processing gas exhaust pipe 12.

[0005] In order to form a predetermined thin film on the surface of the wafer W using the vertical heat treatment apparatus configured as described above, first, the valves (not shown) of the processing gas introduction port 11 and the exhaust port 13 are closed. Then, the wafer boat 7 is raised and the wafer W is accommodated in the reaction vessel 1. Next, the heater 5
After the inside of the reaction vessel 1 is heated to a predetermined temperature, a processing gas is introduced into the reaction vessel 1 from the processing gas introduction pipe 10, and the processing gas is chemically reacted by heat from the heater 5 to form a thin film on the surface of the wafer W. can do.

However, in this type of conventional heat treatment apparatus, since the inner container 30 is formed in a cylindrical shape and has an open upper portion, the inner container 30 is connected through the processing gas introduction pipe 10 to the inner container 30.
The processing gas introduced into the inside flows from the upper opening of the internal container 30 to the outside through the processing gas exhaust pipe 12 through the gap 4 between the internal container 30 and the external container 2, and is generated by the processing gas heated at this time. A thin film is formed on the upper inner surface of the outer container 2. Therefore, there is a problem that the wafer W is subsequently separated and falls as particles, and falls on the surface of the wafer W, thereby causing contamination of the wafer W. Further, the formation of the thin film on the inner surface of the upper portion of the outer container 2 causes distortion due to the formation of the thin film, and also causes cracks, thereby reducing the life of the outer container 2. Therefore, as a means for solving this problem, as shown by the imaginary line in FIG. 11, a sphere depressed downward through a plurality of support members 40 projecting from the opening of the inner container 30 at appropriate intervals. A structure for fixing the cap 41 has been developed (Japanese Utility Model 5-303).
No. 57). According to this structure, the processing gas introduced into the inner container 30 is discharged through the space between the inner container 30 and the spherical cap 41, so that a thin film is formed on the upper inner surface of the outer container 2. Can be prevented.

The inner container 30 is detachably attached to the outer container 2 to facilitate cleaning, maintenance and inspection. That is, FIG. 12 and FIG.
As shown in FIG. 3, a peripheral groove 17a is provided on an inner peripheral surface of a fixing ring 16 provided on a lower inner wall of the outer container 2, and a notch 17b communicating with the peripheral groove 17a is provided on a lower surface of the fixing ring 16.
On the other hand, on the outer peripheral surface of a mounting ring 18 provided on the lower outer wall of the inner container 30, a locking claw 19 that fits into the circumferential groove 17a via the cutout 17b is provided.
After the locking claws 19 are inserted into the notches 17b of the fixing ring 16 and inserted into the peripheral grooves 17a, the inner container 30 can be mounted inside the outer container 2 by rotating. When removing the inner container 30 from the outer container 2, the inner container 30 is removed from the outer container 2 by performing the above operation in reverse.
Can be removed from

At the mounting portion of the outer container 2 and the inner container 30 configured as described above, for example, a stainless fixing plate 50 protruding outward is fixed to the lower surface of the mounting ring 18 with a fixing screw 51. In a state where the inner container 30 is mounted, the fixing plate 50 is pressed against the lower surface of the fixing ring 16 by tightening the fixing screw 51,
This prevents rotation of the inner container 30 from rotating, and
The gap between the fixing ring 16 and the mounting ring 18 is closed to prevent the product of the processing gas carried by the processing gas exhausted from dropping to the inner container 30 side.

[0009]

However, the spherical cap 4 is inserted into the opening of the inner container 30 through the support member 40.
1 is fixed, the plurality of support members 4
Since the spherical cap 41 is fixed and supported via the
Vibration is transmitted to the spherical cap 41 when the wafer boat 7 is raised and lowered, and the vibration causes the thin film formed on the inner surface of the spherical cap 41 to peel off and fall on the wafer, thereby contaminating the wafer W and lowering the yield. There's a problem. Further, such a structure has a spherical cap 4
1 and the support member 40 must be fixed to the opening of the internal container 30, so that many components are required, and the mounting operation is not only complicated, but also the internal container 30 There is also a problem that cleaning of the is troublesome.

[0010] Further, from the processing gas introduction pipe 10 to the inner container 3.
Since a large amount of the processing gas introduced into the inside of the wafer W flows to the side close to the exhaust port 13, the flow of the processing gas becomes non-uniform, and there is a possibility that the film thickness uniformity of the thin film formed on the surface of the wafer W is reduced. .

In the conventional mounting structure of the inner container 30 and the outer container 2, the product of the processing gas can be prevented from falling into the inner container 30 by the fixing plate 50, but the doughnut is fixed to the donut. Due to the flat plate shape, the contact with the fixing ring 16 is insufficient and a gap is generated, and a part of the processing gas introduced into the inner container 30 from the processing gas introduction pipe 10 is partially removed between the inner container 30 and the outer container. Leaks into the gap 4 and flows. For this reason, a predetermined amount of the processing gas is not supplied into the inner container 30, and there is a possibility that the uniformity of the thickness of the thin film formed on the surface of the wafer W is reduced. In order to prevent this decrease in film thickness uniformity, it is sufficient to introduce a large amount of processing gas. However, this causes a problem that the consumption of the processing gas is wasted and the cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims at preventing contamination of an object to be processed, making the flow of processing gas uniform, and making the film thickness of the surface of the object uniform, thereby improving the product yield. An object of the present invention is to provide a vertical heat treatment apparatus for achieving the object.

[0013]

In order to achieve the above-mentioned object, a vertical heat treatment apparatus according to the present invention comprises : a reaction vessel disposed in a heating means; A processing gas introduced into the internal container from an inlet provided at a lower portion of the internal container, and an external container through the internal container and the external container. Assuming a vertical heat treatment apparatus that discharges to the outside from an exhaust port provided at the lower part of the inner container, the inner container is formed in a cylindrical shape with a bottom opening at the bottom, and a circumferential direction at the upper part of the inner container is formed. A plurality of processing gas communication holes are provided, and the area of the processing gas communication hole on the exhaust port side is formed smaller than the area of the processing gas communication hole on the introduction port side.

In this case, the shape of the processing gas communication holes is made the same, and the pitch between the processing gas communication holes is gradually increased toward the exhaust port side, or the pitch of the processing gas communication holes is made equal and the exhaust gas is exhausted. By gradually reducing the diameter of the processing gas communication hole toward the opening, the area of the processing gas communication hole on the exhaust port side can be made smaller than the area of the processing gas communication hole on the introduction port side.

[0015]

According to the vertical heat treatment apparatus of the present invention constructed as described above, the inner container is formed in a bottomed cylindrical shape having an opening at the bottom, and a plurality of processing gases are formed in the upper part of the inner container in the circumferential direction. By providing the communication hole, the processing gas introduced into the internal container flows through the processing gas communication hole into the gap between the internal container and the external container, and flows from the exhaust port to the outside.
Therefore, the processing gas is dispersed from the inner container and flows into the gap between the inner container and the outer container, so that the flow of the processing gas becomes uniform, and the processing film thickness on the surface of the processing object can be made uniform, and the product yield can be improved. Can be improved. In addition, since the processing gas communication hole is provided in the bottomed cylindrical internal container, the product of the processing gas attached to the inner surface of the upper portion of the internal container falls due to the vibration when the object to be processed is carried in and out of the reaction container. And does not contaminate the object.

[0016] Further, by forming the area of the processing gas communication hole on the exhaust port side smaller than the area of the processing gas communication hole on the introduction port side, the gas flows from the inner container to the gap between the inner container and the outer container. can be a flow of process gas into more uniform, it is possible to achieve uniform treatment film thickness of the surface of the object.

[0017]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. Here, a case where the vertical heat treatment apparatus of the present invention is applied to a vertical CVD apparatus will be described. In addition,
The same parts as those of the conventional heat treatment apparatus shown in FIG.

FIG. 1 is a sectional view of a main part of a vertical heat treatment apparatus according to the present invention. The vertical heat treatment apparatus according to the present invention includes a cylindrical outer container 2 having a bottom and made of quartz glass and having a bottom opening.
A reaction vessel 1 consisting of a bottomed cylindrical inner vessel 3 made of, for example, quartz glass or silicon carbide (SiC) and having a lower opening, which is disposed with a gap 4 in the outer vessel 2, and the opening is on the lower surface. A vertically insulated furnace body 6 having a heater 5 as a heating means on its inner wall surface and a plurality of wafers W are vertically arranged in a multistage manner. Quartz wafer boat 7
The main part is constituted by a lifting mechanism (not shown) for raising and lowering the wafer boat 7.

A plurality of processing gas communication holes 20 are formed in the upper part of the inner container 3 in a circumferential direction at appropriate intervals. In addition, an inlet 11 of the processing gas introduction pipe 10 is provided in a lower opening of the inner container 3, and an exhaust port 13 of a processing gas exhaust pipe 12 is provided in a portion of the lower part of the outer container 2 opposite to the introduction port 11. Have been. With this configuration, the processing gas flowing through the processing gas introduction pipe 10 and being introduced into the internal container 3 from the introduction port 11 is dispersed through the processing gas communication hole 20 and is thus dispersed into the internal container 3 and the external container 2. Can flow into the gap 4 between them.

In this case, by providing the processing gas communication holes 20 at equal intervals in the circumferential direction of the internal container 3 as shown in FIG. 2, the processing gas can be dispersed from the internal container 3 to the gap 4 and flow. Yes, but as shown in FIG.
The processing gas communication holes 20 and 2 extend from the first side to the exhaust port 13 side.
By gradually increasing the pitch between 0, the area of the processing gas communication hole 20 on the exhaust port 13 side is formed smaller than the area of the processing gas communication hole 20 on the introduction port 11 side. , The flow of the processing gas flowing into the gap 4 can be made more uniform. As another means for forming the area of the processing gas communication hole 20 on the exhaust port 13 side smaller than the area of the processing gas communication hole 20 on the introduction port 11 side,
For example, as shown in FIG. 4, the pitch of the processing gas communication holes 20 is set to be equal to the processing gas communication holes 2 toward the exhaust port 13 side.
The diameter of 0 may be gradually reduced.

The inner container 3 is detachably attached to the outer container 2 via a seal mechanism described later. In this case, as shown in FIGS. 5 to 9, a connection between a peripheral groove 17 a provided on the inner peripheral surface of the fixing ring 16 provided on the lower inner wall of the outer container 2 and a mounting ring provided on the lower outer wall of the inner container 3. Due to the pawls 19, the inner container 3 is connected to the outer container 2.
The seal member 21 fixed to the mounting ring 18 elastically contacts the lower surface of the fixing ring 16 to seal a gap between the fixing ring 16 and the mounting ring 18 at the time of mounting. That is, the circumferential groove 17 is formed on the inner circumferential surface of the fixing ring 16 provided on the lower inner wall of the outer container 2.
a and 90 on the lower surface of the fixing ring 16.
The notches 17b communicating with the circumferential groove 17a are provided at four positions apart from each other, while the outer circumferential surface of a mounting ring 18 provided on the lower outer wall of the inner container 3 is provided on the outer circumferential surface through the notch 17b.
By providing four locking claws 19 at 90 ° intervals to be fitted in a, the locking claws 19 are notched 17b of the fixing ring 16.
After being inserted into the peripheral groove 17a, the inner container 3 can be attached inside the outer container 2 by rotating in the horizontal direction. Also, the inner container 3 is replaced with the outer container 2
When removing from the inner container 3
Can be removed from the outer container 2. The fixing ring 16 and the mounting ring 18 are made of a material having high heat resistance, corrosion resistance, and rigidity, for example, a member made of stainless steel, Inconel, Hastelloy (trade name), or the like.

In the mounting portion of the outer container 2 and the inner container 3 thus configured, a seal member 21A (a leaf spring seal) formed of, for example, a stepped donut-shaped leaf spring is provided on the lower surface of the mounting ring 18. Are fixed by fixing means such as welding or screwing. This leaf spring seal 21
A is formed of a member such as stainless steel or spring steel, and has a donut-shaped base 22a fixed to the lower surface of the mounting ring 18 and a base 22a.
And a horizontal pressing piece 22c extending horizontally from the tip of the outwardly inclined piece 22b (FIG. 10).
(A)).

The sealing member is necessarily a leaf spring seal 21.
A does not need to be A. For example, as shown in FIGS. 6 and 10B, a donut-shaped base 23a fixed to the lower surface of the mounting ring 18 and a meandering shape upward from the outer peripheral edge of the base 23a Can be formed by a bellows seal 21B composed of a bellows piece 23b extending to the bellows. Also,
As shown in FIGS. 8 and 10 (c), a doughnut-shaped base 24a fixed to the lower surface of the mounting ring 18 is provided with a hollow seal portion 24b on the outer peripheral edge. The sealing member can be formed by an O-ring 21C made of a material rich in odor. In this case, the base portion 24a may be flat, but a dovetail-shaped cross section is provided on the mounting surface of the base section 24a, and the convex section 24c is provided on the lower surface of the mounting ring 18. Groove 18
The O-ring 21 </ b> C can be firmly attached to the attachment ring 18 by fitting into the inside a.

In the above description, the sealing member 21 (21A to 21A) is attached to the lower surface of the mounting ring 18 provided on the inner container 3.
21C), the case where the sealing member 21 is elastically brought into contact with the lower surface of the fixing ring 16 provided on the outer container 2 when the inner container 3 is mounted in the outer container 2 has been described. It is not necessary to adopt such a structure. As shown in FIG. 9, for example, a leaf spring seal 21 </ b> D fixed to the upper surface of the fixing ring 16 may be elastically contacted with the upper surface of the mounting ring 18 for sealing. As shown in FIG. 10D, the leaf spring seal 21D has a donut-shaped base 25a fixed to the upper surface of the fixing ring 16.
And an inwardly inclined piece 25b extending inward from the inner peripheral edge of the base 25a in an inclined manner, and a horizontal pressing piece 25c extending horizontally from the tip of the inwardly inclined piece 25b. The bellows seal 21B and the O-ring 21C can be used instead of the leaf spring seal 21A in the seal portion configured as described above.

By configuring the sealing mechanism as described above, the locking claw 19 of the mounting ring 18 is inserted into the circumferential groove 17a through the notch 17b provided in the fixing ring 16 and rotated in the horizontal direction. When the inner container 3 is mounted in the outer container 2 by the seal member 21 (specifically, a leaf spring seal 21A, a bellows seal 21B, an O-ring 21).
C or a leaf spring seal 21D.
1 will be elastically contacted with the fixing ring 16 or the mounting ring 18, so that the gap between the fixing ring 16 and the mounting ring 18 can be airtightly closed. Therefore, it is possible to prevent the product of the processing gas carried by the exhausted processing gas from falling to the inner container 3 side, and the processing gas introduced into the inner container 3 from the inlet 11 is connected to the inner container 3. Leakage into the gap between the outer containers 2 can be prevented.

On the other hand, the wafer boat 7 is provided with a lid 15 via a heat retaining cylinder 14 below a holding portion 7a for holding the wafers W in multiple stages, and this lid 15 closes the opening of the reaction vessel 1. The inside of the reaction vessel 1 is configured to be sealed by closing. As a result, a predetermined processing gas can be introduced from the processing gas introduction pipe 10 into the internal vessel 3 of the reaction vessel 1 while the inside of the reaction vessel 1 is evacuated from the processing gas exhaust pipe 12, and introduced into the internal vessel 3. The processed gas is heated by the heater 5 and undergoes a chemical reaction, and a thin film generated thereby is formed on the surface of the wafer W stored in the wafer boat 7.

In order to form a thin film, for example, an oxide film on the surface of the wafer W using the vertical heat treatment apparatus configured as described above, first, the valves (not shown) of the processing gas inlet 11 and the exhaust port 13 are set. In the closed state, the wafer boat 7 containing the wafer W is raised by driving the elevating mechanism, and the wafer W is contained in the internal container 3 of the reaction vessel 1. Next, after the inside of the reaction vessel 1 is heated to a predetermined temperature by the heater 5,
The processing gas supplied from the processing gas introduction pipe 10 is supplied to the inlet 1
When the processing gas is introduced into the internal container 3 from the internal container 3, the processing gas rises in the internal container 3, passes through the processing gas communication hole 20 provided around the upper portion of the internal container 3, and forms a gap 4 between the internal container 3 and the external container 2. And exhausted to the outside from the processing gas exhaust pipe 12 through the exhaust port 13. Therefore, the processing gas introduced into the internal container 3 flows uniformly by passing through the processing gas communication holes 20 provided in the circumferential direction. Therefore, it reacts with the heat from the heater 5 in the inner container 3 and can form a uniform oxide film on the surface of the wafer W.

After the oxide film is formed on the surface of the wafer W as described above, the elevating mechanism is driven to lower the wafer boat 7, and the wafer W accommodated in the wafer boat 7 on which the oxide film is formed is removed. It is removed from the reaction vessel 1 and the process is completed.

When the wafer boat 7 is moved up and down, vibration is transmitted to the reaction vessel 1. However, since the processing gas communication hole 20 is directly formed in the internal vessel 3, the vibration is transmitted to the upper inner surface of the internal vessel 3 by the vibration. The generated oxide film does not peel off and fall.

When the inner container 3 is to be periodically cleaned, or when maintenance or inspection is to be performed, the inner container 3 is rotated in the horizontal direction and the mounting ring 18 provided on the inner container 3 is rotated.
After the locking claw 19 is moved to the position of the notch 17 b of the fixing ring 16, the inner container 3 can be pulled out downward and the inner container 3 can be removed from the outer container 2. Therefore, the inner container 3 can be easily removed as compared with a conventional processing apparatus in which the fixing screw is loosened and then the inner container 3 is rotated and removed. Moreover, since the inner container 3 can be removed by rotating the inner container 3, the temperature of the heater 5 does not need to be lowered, and after maintenance and inspection are performed, the inner container 3 is inserted and arranged in the outer container 2 again. Loss time until the next processing is performed can be reduced.

Further, when the inner container 3 is inserted and arranged in the outer container 2, the sealing member 21 is
6 or the elastic ring 18, the gap between the inner container 3 and the mounting portion of the outer container 2 can be hermetically sealed, and the inside of the processing gas introduced into the inner container 3 from the processing gas inlet 11 can be sealed. Leakage into the gap between the container 3 and the external container 2 can be prevented. Therefore, the amount of processing gas used can be set to a minimum and used effectively, and the processing film thickness can be made uniform.

In the above embodiment, the CV of the semiconductor wafer is
Although the D apparatus has been described, it is needless to say that the apparatus can be applied to a heat treatment apparatus for an object other than a semiconductor wafer, such as a glass substrate or an LCD substrate, for example, an oxide film forming apparatus or a diffusion apparatus.

[0033]

As described above, since the vertical heat treatment apparatus of the present invention is configured as described above, the following effects can be obtained.

According to the vertical heat treatment apparatus of the present invention, the flow of the processing gas introduced into the internal vessel from the processing gas inlet can be made uniform, so that the processing film thickness on the surface of the object to be processed is made uniform. Can be achieved. Further, since the area of the processing gas communication hole on the exhaust port side is formed to be smaller than the area of the processing gas communication hole on the introduction port side, the flow of the processing gas flowing from the internal container to the gap between the internal container and the external container is performed. more can be made more uniform, it is possible to achieve uniform treatment film thickness of the surface of the object.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing an example of a vertical heat treatment apparatus of the present invention.

FIG. 2 is a sectional view showing a processing gas communication hole according to the present invention.

FIG. 3 is a sectional view showing another embodiment of the processing gas communication hole.

FIG. 4 is a sectional view showing still another embodiment of the processing gas communication hole.

FIG. 5 is an enlarged sectional view of a portion V in FIG. 1 showing a sealing mechanism for an inner container and an outer container in the present invention.

FIG. 6 is an enlarged sectional view showing another sealing mechanism for the inner container and the outer container.

FIG. 7 is an exploded perspective view showing a mounting portion of the inner container and the outer container.

FIG. 8 is an enlarged sectional view showing still another sealing mechanism for the inner container and the outer container.

FIG. 9 is an enlarged sectional view showing still another sealing mechanism for the inner container and the outer container.

FIG. 10 is a sectional perspective view showing a seal member according to the present invention.

FIG. 11 is a cross-sectional view showing a conventional vertical heat treatment apparatus.

FIG. 12 is an enlarged sectional view of a mounting portion of an inner container and an outer container in a conventional vertical heat treatment apparatus.

FIG. 13 is a sectional view taken along the line AA of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 External container 3 Inner container 4 Gap 5 Heater (heating means) 10 Processing gas introduction pipe 11 Inlet 12 Processing gas exhaust pipe 13 Exhaust port 16 Fixing ring 18 Mounting ring 20 Processing gas communication hole 21 Seal member 21A Plate spring Seal 21B Bellows seal 21C O-ring 21D Leaf spring seal W Wafer (workpiece)

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/205 H01L 21/22-21/24 H01L 21/31 H01L 21/365 H01L 21/38-21/40 H01L 21 / 469 H01L 21/86

Claims (1)

(57) [Claims] 1. A reaction vessel arranged in a heating means, comprising an outer vessel having a lower opening, and an inner vessel arranged in the outer vessel and accommodating an object to be processed, a lower portion of the inner vessel. In the vertical heat treatment apparatus, the processing gas introduced into the internal vessel from the introduction port provided in the vertical container is discharged from the exhaust port provided at the lower part of the external container through the internal container and the external container. The inner container is formed in a bottomed cylindrical shape with a lower opening, and a plurality of processing gas communication holes are provided in a circumferential direction at an upper portion of the inner container, and the area of the processing gas communication hole on the exhaust port side is reduced.
A vertical heat treatment apparatus characterized in that it is formed smaller than the area of the processing gas communication hole on the inlet side.