JP2686465B2 - Heat treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a heat treatment apparatus.

(Prior Art) In manufacturing an object to be processed, for example, a semiconductor wafer, a heat treatment such as an oxidation process, a diffusion process CVD (chemical vapor deposition) process, or the like is performed. For example, decompression to form a thin film on a semiconductor wafer
In the CVD device, the cylindrical quartz reaction tube is evacuated and, for example, S
The i substrate is kept uniform at a temperature of 500-900 ° C., and reaction gases such as SiH ₄ and O ₂ , SiH ₂ Cl and N ₂ O or Si (OC ₂ H ₅ ) ₄ are reacted to form a Si oxide film on the Si substrate. To form. As disclosed in Japanese Patent Laid-Open No. 61-249826, a conventional low pressure CVD apparatus, when forming a Si oxide film on a Si substrate by a CVD reaction, flows through a reaction tube and the reaction gas becomes hot and the Si substrate. React with each other to form a Si oxide film on the Si substrate, but the unreacted gas has a reaction product such as SiO ₂ attached to the inner wall of the reaction tube near the exhaust side at a lower temperature than the reaction section of the Si substrate. In particular, in the metal exhaust part of the reaction tube for exhausting the processing gas, the temperature is low because the sealing material for maintaining the airtightness is cooled, and a considerable amount of reaction products such as SiO ₂ adhere to this vicinity. Therefore, in particular, the reaction product attached to the metal exhaust portion of the reaction tube is separated and floated as the film thickness increases, and becomes a source of particle contamination in the reaction tube. A technique for preventing the reaction product from adhering to the metal part of the reaction tube is disclosed in Japanese Patent Laid-Open No. 294826/1986.

(Problems to be Solved by the Invention) However, in the above-described conventional technique, a quartz protective cover is provided between the reaction tube cooling part and the substrate to be processed so that the cooling part on the inner wall of the reaction tube is not exposed. Although it prevents adhesion of the product to the cooling part, it has the following problems. A sealing material such as an O-ring is used for the joint in order to obtain an airtight joint between the quartz tube forming the reaction chamber and the metal exhaust portion. However, there is currently no sealant that can withstand a high temperature of 500-900 ° C, and generally a sealant that can withstand a temperature of approximately 200 ° C. Therefore, the metal exhaust portion is cooled by water cooling or the like. Therefore, the temperature of the metal exhaust part, especially the inner wall near the exhaust port and the connection part with the vacuum pipe on the exhaust device side, is lowered. Since the protective cover is made of quartz, which has poor heat conduction, the temperature near the heater is relatively high, but there is almost no heat transfer due to heat conduction on the far side, and the exhaust device side far from the heater of the protective cover. A temperature gradient is formed toward the thin cylindrical part of the, and the temperature becomes low, and the reaction product easily adheres to this part. Therefore, there is a problem that the reaction product attached at this portion is separated and floated, enters the reaction tube, and becomes a particle contamination source. Further, the reaction product attached to the exhaust port and the connection portion of the exhaust device with the vacuum pipe has an adverse effect on the exhaust performance and the like, and therefore needs to be cleaned and removed at regular intervals. When these adhered substances are removed by cleaning, a part of the reaction product enters the inside of the reaction tube to cause contamination in the reaction tube, and it takes a lot of time and labor to recover the contamination.

The present invention has been made in consideration of the above points, and an object of the present invention is to provide a heat treatment apparatus that suppresses the adhesion of reaction products to a metal tubular portion and suppresses the generation of particles.

[Configuration of the invention]

(Means for Solving the Problem) The present invention relates to a reaction tube surrounded by a heating section, and a metal tube provided at an end of the reaction tube, connected to an exhaust tube, and provided with a cooling mechanism. A heat treatment apparatus comprising: a tubular part, for introducing a processing gas into the reaction tube to perform a heat treatment of an object to be processed, a relay pipe detachably provided in a part of the exhaust pipe, and the tubular part. And a heat insulating cover made of a good heat conductor provided so as to cover the inner surface of the exhaust pipe up to the relay pipe through a gap, and the gas in the reaction tube is exhausted through the heat insulating cover. A heat treatment apparatus is characterized in that a reaction product is deposited in the relay pipe.

(Operation) According to the present invention, a heat insulating cover made of a good heat conductor is provided so as to cover the inner surface of the exhaust pipe up to the metal tubular portion and the relay pipe, and the gas in the reaction tube is passed through the heat insulating cover. Since it is led to the relay pipe in a gas state and the reaction product is deposited here, the adhesion of the reaction product to the tubular portion can be reduced and the relay pipe is detachably provided. In addition, it is possible to easily remove and clean the attached reaction product, and to suppress particles.

(Example) An example in which the heat treatment apparatus of the present invention is applied to a low pressure CVD apparatus will be described below with reference to the drawings. Decompression as shown in Fig. 1
The reaction vessel for performing the CVD is a cylindrical quartz tube (1) and a gas inlet pipe (2) of 3/8 inch diameter made of stainless steel, for example, which is used as a vacuum seal and introduces a reaction gas at both ends of the tube (1). There is provided a cylindrical front flange (3), which is a stainless steel tubular part. One end of the front flange (3) is hermetically connected to one end of the quartz tube (1) via a sealing material such as an O-ring (4).

On the other end side of the front flange (3), a disc-shaped stainless steel front flange door (5) is O-.
It is held airtight by a ring and is openable and closable. Since the operating temperature limit of the O-ring (4) is about 200 ° C., a cooling mechanism (6) such as water cooling is provided around the O-ring (4) of the front flange (3).
It is cooled to about 0 ° C to prevent deterioration of the O-ring (4) due to heat. The other end of the quartz tube (1) is connected to one end side of a cylindrical flange (7), which is a stainless steel tubular part, via an O-ring (4) so that airtightness is maintained. There is.

Further, on the other end side of the flange (7), an opening is provided in the center in the form of a disc made of stainless steel, and an exhaust cylinder (8) having a length of 30 to 70 mm and an inner diameter of about 30 to 50 mm is provided in the opening. A joined flange flange door (9) is hermetically held and removably mounted via an O-ring (4). Similar to the front flange (3), a cooling mechanism (6) by water cooling is provided around the O-ring (4) of the flange (7) to prevent deterioration of the O-ring (4) due to heating. The axis of the exhaust cylinder (8) of the flange door (9) is provided to be substantially the same as the axis of the quartz tube (1). At the free end of such an exhaust cylinder (8) is made of a metal such as stainless steel or a good heat conductor that does not react with the process gas, and has a length of 50 to 100 mm and an inner diameter of about 50 mm, which is a relay pipe (10). ) Is connected. A bellows (11) that is airtight and can be freely arranged is connected to the other end of the relay pipe (10), and is connected to an exhaust device (12) including a mechanical booster pump, a rotary pump, or the like (not shown). . Further, in the above-mentioned reaction container, a good thermal conductor is provided as follows so as to prevent the exhaust gas from adhering to the above-mentioned O-ring cooling part which is the comparatively low temperature part which is the characteristic of this embodiment. For example, a cylindrical heat insulation cover (13) made of a good conductor such as stainless steel is provided so as to cover the inner wall surface of the flange (7) without thermally insulating it, for example, without contacting it. The heat-insulating cover (13) is made of a good thermal conductor having an outer diameter that is approximately equal to or slightly smaller than the inner diameter of the quartz tube (1), and is made of, for example, stainless steel or a surface-treated metal material that does not react with process gas. The two large and small cylinders are joined so as to be thermally isothermal, and the large diameter cylinder (14) is arranged on the quartz tube side and the small diameter cylinder (15) is arranged on the exhaust device (12) side to be integrated. Connected as an object.

The small-diameter cylinder (15) is formed to have a diameter slightly smaller than the outer diameter of the exhaust cylinder (8), does not substantially contact the inner wall surface of the exhaust cylinder (8), and has a small diameter. Body (1
The length of 5) is formed up to the area where exhaust gas is prevented from adhering. In this embodiment, the length is slightly longer than the length of the exhaust cylinder (8) and is set to a length that is a little over the relay pipe (10), for example, about 1/3 to 1/2 of the length of the relay pipe (10). ing. Further, the heat insulating cover (13) is provided with a plurality of point contact means (not shown) so that the shaft center of the heat insulating cover (13) substantially coincides with the shaft center of the quartz tube (1) as in the case of the flange flange door (9). Of course, the axis may be shifted if necessary.
In addition, a cylindrical resistance heater (1) is provided on the outer circumference of the quartz tube (1) so as to surround the quartz tube (1).
6) is provided coaxially. Heat insulation cover (1
3) is a structure for effectively receiving the heat for heating the object to be processed by the heater (16), particularly radiant heat, that is, it is arranged substantially coaxially with the quartz tube (1). Further, since the heat insulating cover (13) is made of a good heat conductor, the heat absorbed by the heat insulating cover (14) near the heater (16) is conducted to the entire area where the heat insulating cover (13) is formed. However, there is little temperature gradient depending on the location in the heat insulating cover (13), and the heat can be kept substantially even.

In the quartz tube (1), a quartz boat (18) on which a plurality of objects to be processed, for example, semiconductor wafers (17) are arranged and mounted can be housed. The quartz boat (18) can be loaded and unloaded by a soft landing (not shown), a robot device or the like by opening and closing the front flange door (5). In this way, the low pressure CVD apparatus is constructed.

Next, the operation operation will be described. That is, the quartz board (18) on which the semiconductor wafers (17) are arranged is loaded into the quartz tube (1) at a predetermined position by a soft landing device (not shown). The semiconductor wafer (17) aligned and mounted on the quartz boat (18) in the quartz tube (1) is heated to a desired temperature, for example, 600 to 800 ° C. by the heater (16), and the pressure in the quartz tube (1) is exhausted. (12) is activated to reduce the pressure to a predetermined pressure, for example, 0.1 to 1.0 Torr. Then, a process gas such as tetraethoxysilane Si (OC ₂ H ₅ ) ₄ is supplied from the gas introduction pipe (2) at a predetermined flow rate, for example, 50 to 120 SCCM.
Flow. Since a predetermined process condition is set on the semiconductor wafer (17), a SiO ₂ film grows.

Further, the high temperature unreacted process gas is rapidly cooled to the above heat resistant temperature of the O-ring near the cooled flange (7) and the flange door (9). On the inner wall of the reaction product SiO ₂
Adheres. In order to prevent the adhesion of the reaction product, it is necessary to maintain the periphery of the flange at a temperature substantially equal to a predetermined process temperature or at a temperature at which the reaction product is hard to be generated, for example, 200 ° C. or higher.

Therefore, in this embodiment, a heat insulating cover (13) is provided as a countermeasure. And it is characterized by utilizing the heat from the heater (16) to keep it warm. That is, it is considered that the heat propagation inside the reaction vessel composed of the quartz tube (1) and the flange portion is mostly due to radiation rather than conduction or convection due to the reduced pressure (vacuum) in the reaction vessel. Therefore, as a feature of this embodiment, the heat insulating cover (13) made of a good heat conductor is provided so as to cover the surfaces of the cooled flanges (7) and the flange doors (9) and so as not to contact the surfaces. Since the axes of the heat insulating cover (16) and the heat insulating cover (13) are substantially coincident with each other, the radiant heat from the heater (16) extends over the entire heat insulating cover (13) as shown in FIG.
Further, the amount of heat decreases, but the cylindrical body with a small inner diameter is thin (15).
Goes all the way inside. Further, since the temperature goes down to the side of the flange (7), the door (9) of the flange, and the pipe (10) for relay, when the heat insulating cover (13) is a heat-defective conductor such as quartz, the quartz tube (1) side. To relay piping (10)
As it goes to the side, the temperature is affected by the above-mentioned outer peripheral temperature, and a temperature gradient is generated, so that the temperature is easily lowered to 200 ° C. or less in the vicinity of the relay pipe (10), and the small diameter cylindrical body (15) of the heat insulating cover (13) ), The reaction product is likely to adhere to the vicinity.
However, one of the features of this embodiment is the heat insulation cover (13).
Is a good conductor of heat, so a large amount of heat received in the closer part of the heater (16) is conducted to the relay pipe (10) side of the small diameter cylindrical body (15) of the heat insulating cover (13). Then
The heat-retaining cover (13) has a small temperature gradient and an almost uniform temperature distribution.
It is possible to keep the temperature above ℃. Lilla flange door (9)
Since the temperature of the relay pipe (10) provided on the side of the exhaust device (12) of the relay pipe (10) is drastically lowered to, for example, 100 ° C. or lower as compared with the heat insulating cover (13), the reaction product is likely to adhere to the relay pipe (10). However, since this relay pipe (10) is configured to be removable, it can be easily removed and washed. Then, the reaction product is generated at a position apart from the semiconductor process region, so that the reaction product is less likely to return to the reaction container and become a pollution source.

The heat insulation cover (13) is the exhaust flange (7).
Not only on the side, but in a region where the reaction product adheres at a relatively low temperature portion, for example, even if a heat insulating cover having a shape matching the front flange (3) side is provided on the front flange (3) side, the reaction product is generated. It has the effect of avoiding adhesion of objects.

Next, tetraethoxysilane Si (OC ₂ H ₅ ) ₄ is added to 70 to 100
SCCM, reaction vessel pressure 0.3 to 1.0 Torr, process temperature 700
When the adhesion state of the reaction product was examined under the condition of ℃,
The reaction product adheres as shown in the figure, and a small amount of adhered matter (21) is observed at the tip position of the small diameter cylindrical body (15) of the heat insulating cover (13) closest to the exhaust device (12) side. so,
A large amount of cross-section (22) adhered to the relay pipe (10) without the heat insulating cover (13), confirming the effect of the heat insulating cover (13). The amount of adhered matter (21) adhered is smaller than that of the cylindrical body (15).
The shorter the length, the smaller the adhesion amount, and the longer the length, the larger the adhesion amount. It is clear that this is due to the amount of heat radiation received from the heat source heater (16). When the inner diameter of this small-diameter cylindrical body is 35 to 40 mm, a length of about 50 mm is appropriate.

Since the relay pipe (10) is configured to be removable, it is possible to take a clean measure by removing and cleaning it. Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the gist of the present invention. Especially low pressure CVD
It is effective for heat treatment equipment such as equipment, TEOS equipment, atmospheric pressure CVD equipment, plasma CVD equipment, dry etching equipment, LCD etching equipment, and ashing equipment.

In the above embodiment, an example in which the heat insulation cover is provided in a cylindrical shape has been described, but the structure can be selected within the range in which the effect of the present invention is obtained. For example, it may be formed in a lattice shape, a slit shape, an arrangement of divided pieces, or a thin plate.

〔The invention's effect〕

According to the present invention, it is possible to reduce the adhesion of the reaction product to the metal tubular portion, and since the relay pipe is provided detachably, it becomes easy to clean and remove the adhered reaction product, Generation of particles can be suppressed.

[Brief description of the drawings]

FIG. 1 is a depressurized CV for explaining an embodiment of the device of the present invention.
FIG. 2 is a diagram for explaining the configuration of the D device, FIG. 2 is a diagram for explaining radiant heat propagation of the heater heat of FIG. 1 to the heat insulating cover, and FIG. 3 is a diagram for explaining the state of adhesion of reaction products by the device in FIG. 1 ... Quartz tube, 3 ... Front flange 4 ... O-ring, 5 ... Front flange door 6 ... Cooling mechanism, 7 ... Lya flange 8 ... Exhaust cylinder, 9 ... Lya flange door 10 ... … Relay pipe, 12 …… Exhaust device 13 …… Heat-insulating cover, 14 …… Large diameter cylinder 15 …… Small diameter cylinder, 16 …… Heater 17 …… Semiconductor wafer, 18 …… Quartz boat

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 21/31 H01L 21/302 B

Claims (1)

(57) [Claims] 1. A reaction tube surrounded by a heating portion, and a metal tubular portion provided at an end of the reaction tube, connected to an exhaust pipe, and provided with a cooling mechanism. In a heat treatment apparatus for introducing a processing gas into a reaction tube to heat-treat an object, a relay pipe detachably provided in a part of the exhaust pipe, an inner surface of the tubular portion and the relay pipe. A heat insulating cover made of a good heat conductor provided so as to cover the inner surface of the exhaust pipe through a gap, and the gas in the reaction pipe is exhausted through the heat insulating cover, and a reaction is generated in the relay pipe. A heat treatment apparatus for depositing a substance.