JP2714576B2 - 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 heat treatment apparatus .

[0002]

2. Description of the Related Art In a heat treatment process in a semiconductor manufacturing process, for example, the degree of flow of highly corrosive gas into a heat treatment reaction tube has increased. For example, in a hydrochloric acid oxidation process, by adding a few percent of HCl to dry O ₂ gas, there is an effect of capturing metal impurities such as Na in a stable form, and a device having stable characteristics can be manufactured. In addition, by performing a heat treatment on the oxidation reaction tube with dry O ₂ gas to which HCl is added at a high temperature for a certain period of time at a high temperature, dirt in the reaction tube can be removed, and a stable process can be expected. There are various benefits such as possible.

However, it is difficult to manufacture all the devices around the reaction tube from quartz glass or the like so as to withstand highly corrosive gas due to problems of strength and dimensional accuracy. For example, a manifold for holding the reaction tube or an opening of the reaction tube is required. The parts made of metal such as caps that close the parts are made of corrosion-resistant stainless steel (SU
S) or made of SU to further increase corrosion resistance
Corrosion-resistant methods such as coating a Ni-based alloy on the surface of S have been adopted. In particular, when a highly corrosive HCl gas or the like is used, a metal in which the surface of SUS is coated with a Ni-based alloy is used as a metal in a portion in contact with the corrosive gas. Japanese Patent Publication No. 57-52423 discloses a technique of coating a metal oxide layer for preventing corrosion of the inner wall of a reaction vessel such as a plasma etching apparatus.

[0004]

However, as shown in FIG. 5, a usual coating is a coating of a corrosion-resistant oxide film, that is, a passive film 2, on a surface of a base metal 1 such as stainless steel or aluminum. However, the base material 1 contains various crystal defects and segregation of impurities. For example, a crystal grain boundary 3 which is a boundary between crystals is formed on the surface of the base material 1.
Is present at the grain boundaries, the coated passive film 2 is not strong and the film is broken, and this is the starting point of corrosion, and corrosion begins. To prevent this drawback, a second passivation film 5 is applied. However, a defect 6 such as a pinhole is formed in the passivation film 5 and corrosion starts again from the defect 6, so that this defect is reduced. The third passivation film 7 and the coating are applied several times.

[0005] The strength of the corrosion resistance in this way, corrosion gas,
This is the time required to propagate the defects of the passivation film applied multiple times and finally reach the base metal. Also, for example, SUS
The base material with Ni coating is SUS without coating in an atmosphere filled with HCl gas.
Compared with 316, the corrosion rate is about 1/10, that is, about 10 times higher. However, in actual processes such as HCl, there are places where even SUS coated with severe corrosion cannot be used, and even if the corrosion is not so severe, it will lead to the generation of dust and the like. Has to be stopped and maintenance takes a very long time.

The present invention has been made in order to improve the above-mentioned points, and an object thereof is to provide a processing apparatus having excellent corrosion resistance.

[0007]

According to the present invention, one end is closed.
Is a process tube that the other end is open, the
A heating device provided to surround the process tube,
This process tube is connected to the other end of the process tube.
Constitutes a process vessel together with a gas tube,
A cylindrical metal manifold with exhaust and exhaust pipes,
On the opposite side of the process tube from this manifold
A metal lid for closing the opening of the end portion hermetically, many
Semiconductor wafers are loaded and moved with the lid
Comprising a boat is loaded into the process tube, a front
The semiconductor wafer is placed in the process tube by the heating device.
Processed by processing gas from gas inlet pipe while being heated by
Heat treatment apparatus, the manifold and the lid
At least the surface of the inside of the process tube is covered with a cover made of quartz glass via a gap, and inert gas introduction means for introducing an inert gas into the gap is provided.

[0008]

According to the present invention, the number of manifolds and lids is small.
Stone with a gap the Kutomo process tube interior surface of the
By covering the gap with an inert gas introducing means and purging the gap with an inert gas while covering with a cover body made of British glass, there is an effect that the corrosion resistance can be extremely increased.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the processing apparatus of the present invention is applied to a vertical CVD apparatus will be described below with reference to the drawings. Vertical CV
As shown in FIG. 1, the D apparatus has a cylindrical process tube 21 which forms a processing chamber and has a vertical axis in the axial direction. The process tube 21 is made of, for example, quartz glass having excellent corrosion resistance. 21a and an inner cylinder 21b.
b, there is a boat 23 made of, for example, quartz glass which supports a plurality of objects to be processed, for example, semiconductor wafers 22 in a horizontal state and vertically separated from each other.
Can be carried in the vertical direction, and below the boat 23, the boat 23 is positioned on the furnace core, and a heat retaining cylinder 24 for preventing heat in the process tube from escaping downward is arranged. In addition, a process gas introduction pipe 25 made of, for example, quartz glass having excellent corrosion resistance or made of, for example, stainless steel having an inner surface which is amorphous coated as described later is inserted and supported from the lower end toward the upper end of the inner cylinder 21b. A gas ejection hole 26 is provided substantially at the center of the wafers 22 arranged and supported by the boat 23, and substantially half the circumference to 4/5 of the inner cylinder 21b at a position facing the ejection hole 26. A plurality of gas discharge holes 27 are formed around the circumference. The exhaust gas such as the process gas is led to the outer cylinder 21a through the discharge hole 27, and the gas is discharged through the gas outlet 28a of the annular manifold 28 made of, for example, stainless steel holding the lower end of the outer cylinder 21a. The air is exhausted by an exhaust pipe (not shown) connected to the outlet 28a.

A resistance heating heater made of, for example, a Kanthal wire is disposed around the process tube 21 as a heating device 29 so as to surround it. Then, the boat 23 is loaded into and unloaded from the process tube 21 by vertically moving the stainless steel disc-shaped lid 30 which holds the heat retaining cylinder 24 and abuts on the manifold 28 to keep the airtight inside the process tube. Loader device 31 to load
Is provided. The manifold 28 and the lid 3
A seal member (not shown), for example, an O-ring is provided at a contact portion with 0 to maintain airtightness. In addition, the heat retaining cylinder 24 can be configured to be rotatable, and the temperature and gas uniformity can be improved.

For example, the manifold 28 or the lid 30 is made of a metal such as stainless steel, and the portion having insufficient corrosion resistance is provided on the inner surface of the base metal 13 as shown in FIGS. A cover body 12 made of, for example, quartz glass or the like (in FIG. 1, the solid line itself is a cover body) is provided so as to cover the base metal 13 with the gap 11 interposed therebetween. An inert gas introducing means (not shown) for introducing an inert gas such as _two gases into the gap 11 is connected, and the space between the base metal 13 and the cover body 12 is purged with, for example, N ₂ gas.

For example, a manifold 28 made of stainless steel
Is a portion that may come into contact with the reaction gas and the reaction product at the inner exposed surface 40 and the inner surface 42 of the tubular gas outlet 28, and the outer tube 21a and the inner tube 2 of the process tube.
The cover body 12 is provided on a portion of the surface 41 that comes into contact with 1b. Further, for example, a cover 30 made of a material stainless steel is provided on the inner surface 43 which comes into contact with the manifold 28 to form a reaction vessel and may come into contact with a reaction gas or a reaction product.

Next, the operation of the above vertical CVD apparatus will be described. The wafer 22 is transferred from the cassette to the boat 23 by a wafer transfer device (not shown), the boat 23 on which the wafer 22 is loaded is raised by a predetermined amount by the loader device 31, and the process tube is moved to a predetermined position in the process tube 21. Without being brought into contact with the inner wall of the inner cylinder 21b. At this time, by bringing the manifold 28 below the process tube 21 into contact with the lid 30, the wafer 22 is automatically positioned and the inside of the process tube 21 is airtight. Next, the inside of the process tube 21 is set to a desired pressure state, for example, 0.1-3.
Evacuation is controlled by a vacuum pump (not shown) so as to maintain the pressure at Torr, and a desired temperature, for example, 600 to 12
Set to about 00 ° C. After this setting, the reaction gas, for example, SiH _{2 is} controlled while controlling the flow rate from a gas supply source using a mass flow controller (not shown) while controlling the exhaust gas.
When Cl ₂ (dichlorosilane) and H ₂ (hydrogen) are supplied into the process tube 21 from the gas introduction tube 25 for a predetermined time, the following Si film is deposited on the surface of the wafer 22 installed in the process tube 21.

SiH ₂ Cl ₂ + H ₂ → Si + 2HCl In this case, HCl having a strong oxidizing power is generated in the process tube 21. However, the cover 12 is provided on the inner surfaces of the metal manifold 28 and the lid 30 while forming the process vessel, and an inert gas is introduced into the gap 11 between the metal surface and the cover 12. Since the inert gas is introduced by the means and the gap is purged with the inert gas, the reaction gas and a reaction product such as HCl are less likely to contact or accumulate on the inner surface of the metal part, so that corrosion is less likely to occur. . Therefore, generation of dust due to corrosion can be suppressed, and the process tube 2
1 and the wafer 22 can be prevented from being contaminated.

After such a CVD process, the supply of the reaction gas is stopped, and an inert gas such as N ₂ gas is introduced into the gas introduction pipe 25.
After returning to normal pressure in the process tube, the boat 23 loaded with the wafer is loaded into the loader device 3.
By 1, it is taken out of the process tube 21 and transferred to a transfer device (not shown) to complete the processing.

In the above-described embodiment, the vertical CVD apparatus is described. However, the present invention is not limited to the above-described embodiment. The effect of sex can be expected. For example, as shown in FIG. 3, the exhaust part of the processing apparatus is, for example, a stainless steel box-shaped scavenger 51 for exhausting exhaust gas from the processing chamber. There is an annular ring, for example, a stainless steel manifold 52 for holding the reaction tube. The opening of the manifold 52 is heat-shielded during processing (exhaust gas or the like flows), and a quartz glass boat loaded with wafers is loaded and unloaded into the reaction tube. During loading, a disc-shaped shutter 53 made of, for example, stainless steel is driven by a driving mechanism 54 composed of, for example, an air cylinder so as to be retracted. Exhaust gas and reaction products from the reaction tube pass through the exhaust pipe 55 and are discharged from the scavenger 51 to an external exhaust treatment device maintained at a negative pressure.

As described above, the reaction gas or the reaction product during the process flows or adheres into the scavenger 51 and is easily oxidized and corroded. Therefore, the inner surface of the scavenger 51, the entire surface of the shutter 53, and the driving mechanism 54
It is preferable to provide the cover body 12 on metal devices and components disposed inside the scavenger 51, the exhaust pipe 55, and other components disposed or attached inside the scavenger 51. As described above, in addition to the CVD device and the diffusion / oxidation device, the same effect can be obtained by an etching device, an ashing device, and the like.

[0018]

As described above, according to the present invention, the manifold
Hold and lid at least inside process tube
By covering the surface with a cover made of quartz glass through a gap and introducing an inert gas into this gap, the corrosion resistance is very high, the maintainability is good, and the generation of dust due to corrosion is extremely small. can Ru. Therefore par
For semiconductor wafers with narrow tolerance of tickle adhesion
Also, using a heat treatment device using a metal manifold
It can be treated with highly corrosive gas.

[Brief description of the drawings]

FIG. 1 shows a vertical type C for explaining an embodiment of the apparatus of the present invention.
It is a block diagram of a VD apparatus.

FIG. 2 is an explanatory diagram for explaining a cover body.

FIG. 3 is an explanatory diagram of another embodiment.

FIG. 4 is an explanatory view of a conventional coating.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Gap 12 Cover body 13 Base metal 21 Process tube 21a Inner cylinder 22 Wafer 23 Boat 28 Manifold 30 Lid

Claims (1)

(57) [Claims] 1. One end is closed and the other end is open.
Process tube and a heating device provided around the process tube
When connected to the other end of the process tube this process
Constitutes a process vessel together with a gas tube,
And a cylindrical metal manifold provided with exhaust and exhaust pipes, and a side of the manifold opposite to the process tube.
A metal lid for hermetically closing the opening at the end, and a large number of semiconductor wafers are loaded and moved together with the lid.
And a boat to be carried into the process tube
The semiconductor wafer is placed in the heating tube in a process tube.
Process gas from the gas introduction pipe
In the heat treatment apparatus to be treated , at least the process tube of the manifold and the lid is processed.
The inside surface of the bulb is covered with a cover made of quartz glass via a gap, and inert gas introduction means for introducing an inert gas into the gap is provided.
Heat treatment equipment .