JP2000106347A - Method and device for processing object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress particles from being generated in a reaction tube and to manufacture a high-quality semiconductor device at high yield. SOLUTION: A sub-bypass pipe 65 equipped with a sub-valve SSV is formed parallel to a slow-exhaust bypass pipe 64 of an evacuation system of a thermal process apparatus. While the sub-valve SSV is opened to evacuation through the sub-bypass pipe 65, a wafer boat 14 is loaded or unloaded from a reaction pipe 11, and sticking of sublimation gas which is a reaction by-product and particles to a semiconductor substrate 15 are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for treating an object which is a heat treatment type, and more particularly to an apparatus for treating particles adhered to the object due to sublimation of a reaction by-product. The present invention relates to a processing apparatus and a processing method for an object that can be prevented.

[0002]

2. Description of the Related Art Generally, a vertical heat treatment apparatus reacts a cylindrical reaction tube (reactor) made of quartz or the like, a heater, and a semiconductor substrate (wafer), which is an object to be processed, mounted on a wafer boat. The apparatus includes a loading mechanism for loading the wafer boat after the processing and unloading the processed wafer boat from the inside of the reaction tube, a gas supply pipe for supplying a processing gas into the reaction tube, and an exhaust pipe for exhausting gas in the reaction tube. The semiconductor substrate to be processed is placed on a wafer boat and loaded into a reaction tube, and under heating, a processing gas is supplied to the reaction tube, and the semiconductor substrate and the processing gas react with each other or the processing gases react with each other. Then, a film forming process is performed on the surface of the semiconductor substrate. After the film forming process, the wafer board is unloaded from the reaction tube, the semiconductor substrate is pulled out from the wafer boat, and the semiconductor substrate is transported to the next step.

[0003]

SUMMARY OF THE INVENTION A vertical heat treatment apparatus includes:
When a film is formed, a reaction by-product adheres. In particular, the temperature of the vicinity of the manifold and the exhaust provided at the lower part of the reaction tube is lower than that of the film forming region where the wafer boat is arranged, and thus reaction by-products adhere.

[0004] The attached reaction by-products are adsorbed on the semiconductor substrate during loading and unloading into the reaction tube of the wafer boat, which is one of the causes of particle generation. For example, during the formation of a silicon nitride film (SiN film), ammonium chloride (NH ₄ Cl) solidifies at a low temperature in the reaction tube. It is considered that when the ammonium chloride sublimates during the loading of the semiconductor substrate and is adsorbed on the semiconductor substrate, the ammonium chloride becomes a seed in a subsequent film forming step, and particles are formed on the substrate surface. It is also considered that particles formed by the reaction between sublimed ammonium chloride and moisture in the atmosphere are adsorbed to the semiconductor substrate and cause defects. Therefore, it may be difficult to manufacture a high-quality semiconductor device at a high yield rate. With the configuration of the conventional vertical heat treatment apparatus, it is difficult to completely prevent the generation of reaction by-products in the reaction tube, and improvement is desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and has an object to suppress the generation of particles in a reaction tube and to manufacture a high-quality semiconductor device or the like at a high yield rate. And a method for treating an object to be treated.

[0006]

In order to achieve the above object, an object processing apparatus according to a first aspect of the present invention includes a reaction tube for accommodating a plurality of objects and performing processing. A loading mechanism for loading an object to be processed into the reaction tube and unloading the processed object; an exhaust passage connected to the reaction tube for discharging gas in the reaction tube; An exhaust means connected to the passage for exhausting gas in the reaction tube; a main valve arranged in the exhaust passage for opening and closing the exhaust passage; and connecting the exhaust passages across the main valve. A bypass passage for exhausting the gas in the reaction tube at a flow rate smaller than the gas flow rate in the exhaust passage; a bypass valve disposed in the bypass passage to open and close the bypass passage; Connecting the exhaust passages across the valve, and during the operation of loading or unloading the object to be processed, a sub-bypass passage for exhausting the gas in the reaction tube at a flow rate smaller than the gas flow rate of the bypass passage. A sub-valve arranged in the sub-bypass passage to open and close the sub-bypass passage. The sub-valve is opened, and the gas in the reaction tube is exhausted by the exhaust means, while the gas is exhausted by the loading mechanism. Loading or unloading the treatment body into or from the reaction tube.

According to this structure, the object to be processed, such as a semiconductor substrate, is loaded or unloaded while the gas in the reaction tube is exhausted by the sub-bypass tube. Adsorption to the processing body is small, and defects in the manufactured device can be suppressed.

In the processing apparatus for the object to be processed, for example, the object to be processed is loaded while the sub-valve is opened and the gas in the reaction tube is exhausted by the exhaust means. Until the pressure is reached, the sub-valve is opened, and the gas in the reaction tube is exhausted by the exhaust means. After the inside of the reaction tube reaches the first pressure, the bypass valve is opened, and the inside of the reaction tube is exhausted by the exhaust means. After the inside of the reaction tube reaches a second pressure lower than the first pressure, the main valve is opened, and the gas in the reaction tube is exhausted by the exhaust means.

The exhaust means is, for example, -5 to -70 mm with respect to the atmospheric pressure through the opened sub-valve.
The gas in the reaction tube is exhausted at a pressure difference of H ₂ O (preferably −10 to −50 mmH ₂ O).

The apparatus for processing an object to be processed is an apparatus for supplying an NH ₃ gas and a SiH ₂ Cl ₂ gas into the reaction tube to form a SiN film on the object to be processed. At the time of and / or at the time of unload operation, by opening the sub-valve and performing exhaust by the exhaust means,
A sublimation gas of NH ₄ Cl, which is a reaction by-product, is prevented from flowing to the object.

Further, in the method for treating a workpiece according to a second aspect of the present invention, the workpiece is loaded into a reaction tube, and the loaded workpiece is subjected to a predetermined film forming process involving heat treatment. In the method for processing an object to be unloaded, the object to be processed is loaded into the reaction tube and / or unloaded from the reaction tube while exhausting gas from the reaction tube. Features. According to this method as well, it is possible to suppress the adsorption of particles to the object to be processed and the like, and to suppress defects of the manufactured apparatus and the like.

The pressure difference with respect to the atmospheric pressure at the time of evacuation is, for example, −5 to −70 mmH ₂ O (preferably −10 to −5 mm).
0 mmH ₂ O).

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a configuration of a vertical heat treatment apparatus according to an embodiment of the present invention. This vertical heat treatment apparatus includes a cylindrical reaction tube 11 whose longitudinal direction is directed vertically as shown in FIG. The reaction tube 11 is composed of an outer cylinder 12 having a lower end opening made of a heat-resistant material, for example, quartz, and an inner cylinder 13 having upper and lower openings which are concentrically housed in the outer cylinder 12 and are appropriately separated from the inner wall thereof. It has a double tube structure.

A wafer boat (heat treatment boat) 14 made of quartz or the like is provided in the reaction tube 11. In the wafer boat 14, semiconductor substrates (semiconductor wafers) 15, which are objects to be processed, are stacked and housed at predetermined intervals in the vertical direction.

At the periphery of the reaction tube 11, a heating heater 16 formed of a resistance heating element or the like is provided so as to surround the reaction tube 11.

An outer cylinder 1 is provided below the outer cylinder 12 and the inner cylinder 13.
A stainless steel manifold 17 that supports the inner cylinder 2 and the inner cylinder 13 is provided. A flange 18 is formed in an annular shape at the upper end of the manifold 17, and is configured to be hermetically sealed via a flange 19 formed at a lower end of the outer cylinder 12 and an O-ring 20 made of an elastic member. ing. The lower end of the inner cylinder 13 is placed on a support 21 formed to protrude inward from the inner wall of the manifold 17.

First and second gas supply pipes 31 and 41 made of quartz or the like bent toward the heat treatment section (upward) are inserted through one side surface of the manifold 17 through a seal member. .

A first gas pipe 33 is connected to the first gas supply pipe 31 via a joint 32. The first gas pipe 33 has a mass flow controller (MFC) 34 for adjusting a gas flow rate and a valve VB1 for controlling a gas flow.
To the first gas source 35. The first gas source 35 is, for example, a gas source of ammonia (NH ₃ ). Further, the first gas pipe 33 is also connected to a nitrogen gas source 36 via an MFC 34 and a valve VB3.

A second gas pipe 43 is connected to the second gas supply pipe 41 via a joint 42. The second gas pipe 43 has a mass flow controller (MFC) 44 for adjusting a gas flow rate and a valve VB2 for controlling a gas flow.
To the second gas source 45. Further, the second gas pipe 43 is also connected to a nitrogen gas source 46 via the MFC 44 and the valve VB4.

At the opening at the lower end of the manifold 17, a disk-shaped lid 51 is provided so as to be airtightly sealed via an O-ring 52 made of an elastic member. On the upper surface of the lid 51, a heat retaining cylinder 53 is arranged, and the wafer boat 14 is mounted on the heat retaining cylinder 53. The lid 51 is attached to an elevating mechanism 54 that moves vertically to load and unload (load / unload) the heat retaining cylinder 53 and the wafer boat 14 placed on the upper surface of the lid 51. Have been.

An exhaust pipe 61 is connected to the other side of the manifold 17. The exhaust pipe 61 is made of stainless steel or the like, and is connected to an exhaust pipe 63 having a diameter φ of about 50 to 200 mm via a joint 62. Exhaust piping 63 (6
3a, 63b, 63c) are connected to the vacuum pump VP via the main valve MV and the trap TRP in order. The trap TRP includes a disk trap, a water trap, and the like, and adsorbs particles in exhaust gas. The vacuum pump VP has an exhaust capacity of about 15,000 to 20,000 liters / minute.

The exhaust pipes 63 (63a and 63b) straddle the main valve MV (in parallel with the main valve MV).
A bypass pipe (so-called slow vacuum line) 64 and a sub-bypass pipe 65 are arranged.

When the inside of the reaction tube 11 is evacuated, the bypass tube 64 is evacuated gradually at the beginning of the evacuation to prevent the semiconductor substrate 15 from moving and from winding up the reaction by-product. It is provided for so-called slow exhaust. The flow rate (exhaust flow area) of the bypass pipe 64 is set sufficiently smaller than the exhaust flow rate (exhaust flow area) of the exhaust pipe 63. The bypass pipe 64 is made of, for example, stainless steel, has a diameter of about 10 mm to 30 mm, and includes a bypass valve (slow vacuum valve) SV.

The sub-bypass pipe 65 loads (loads) or unloads (unloads) the wafer boat 14 from the reaction tube 11.
In this case, the inside of the reaction tube 11 is slightly exhausted. The sub bypass pipe 65 shares a part of the pipe with the bypass pipe 64. This sub-bypass pipe 65 is
The flow rate (flow area) is made of stainless steel or the like, and the flow rate (flow area) is smaller than the exhaust flow rate (flow area) of the bypass pipe 64. For example, the diameter is formed to about 3 mm to 10 mm, and the needle valve NV and the needle valve NV And a sub-valve SSV provided in series. Needle valve NV
The value of the pressure difference across the valve is predetermined, for example, the atmospheric pressure -5~-70mmH ₂ O (-0.05
The opening degree is adjusted in advance so as to be −0.7 kPa). The sub-valve SSV opens and closes the sub-bypass pipe 65.

Next, the operation of this vertical heat treatment apparatus will be described with reference to the timing chart of FIG. 3 showing the opening and closing timing of each valve, taking as an example the case of forming a silicon nitride film Si ₃ N ₄ . .

The heating heater 16, the mass flow controllers 34 and 44, the valves VB1 to VB4, MV, S
V, SSV, gas sources 35, 36, 45, 46, elevating mechanism 54, auto pressure controller (not shown),
The vacuum pump VP is connected to a controller (not shown) for controlling these. The controller measures the temperature, pressure, and the like of each part of the vertical heat treatment apparatus using a sensor (not shown), and automatically controls a series of processing described below by supplying a control signal or the like to each part.

First, as shown in FIG. 2, in a state where the elevating mechanism 54 is lowered, the wafer boat 14 on which the semiconductor substrate 15 is mounted is mounted on the heat retaining cylinder 53. At this time, the heating heater 16 is set at about 700 to 800 ° C.
Heat to about.

Next, the vacuum pump VP is activated and the sub-valve SSV is opened to start exhausting the gas in the reaction tube 11. Is moved upward, whereby the wafer boat 14 is loaded into the reaction tube 11. At this time, -5~-70mmH ₂ O pressure differential is the atmospheric pressure in the interior of the reaction tube 11 and the inner exhaust pipe 63 (or the inlet side and the outlet side of the needle valve), desirably, -10～-
50 mm H ₂ O such that (-0.1 to-0.5 kPa) degree, adjusts the opening degree of the needle valve to open the sub-valve SSV. Due to this pressure difference, the gas in the reaction tube 11 is exhausted, and as shown conceptually in FIG. 4, sublimation gas of a reaction by-product, particles formed by reacting the sublimation gas with moisture in the atmosphere, Other suspended particles are exhausted through the exhaust pipe 63. Further, since the pressure difference is small and the exhaust is relatively gentle, the gas in the reaction tube 11 is not disturbed, and the deposit is not rolled up. For this reason, these sublimation gases and particles are transferred to the semiconductor substrate 15 during loading.
Without being adsorbed by the trap TRP via the exhaust pipe 63.

Even after the loading of the wafer boat 14 into the reaction tube 11 is completed and the flange 22 and the lid 51 formed at the lower end of the manifold 17 reach an airtight state via the O-ring 52, for a while, Exhaust is continued as it is. When the pressure in the reaction tube 11 drops to about 20 Torr, the bypass valve SV is opened (at this time,
The sub-valve SSV may be closed), and the exhaust is continued. When the pressure in the reaction tube 11 drops to about 5 Torr, the main valve MV is opened (at this point, the bypass valve SV and the sub-valve SSV may be closed), and the inside of the reaction tube 11 is maintained at a predetermined pressure, for example, 4 to 5 minutes. Reduce the pressure to × 10 ⁻³ Torr.

As described above, by sequentially opening the valves SSV, SV, and MV and gradually increasing the exhaust capacity,
The pressure fluctuation in the reaction tube 11 is moderated, and the main evacuation is performed when the evacuation progresses and the movement of the semiconductor substrate 15 to be processed and the particles do not roll up.

When the pressure in the reaction tube 11 reaches a predetermined value,
The valves VB1 and VB2 are opened and N
The H _3, to adjust the temperature of the semiconductor substrate 15 by heater 16 with the _SiH 2 Cl ₂ from the second gas source 45 is supplied to the reaction tube 11 to 600 to 700 ° C.. During this time, the exhaust is continued while the main valve MV is opened, and the pressure in the reaction tube is controlled to 0.2 to 0.4 Torr by the auto pressure control, and the pressure is maintained for a predetermined time, for example, 2 hours. A film is formed from Si ₃ N ₄ .

During this film forming process, ammonium chloride NH ₄ Cl adheres to a relatively low temperature portion such as the vicinity of the manifold 17 or the exhaust pipe 61.

After the film forming process is completed, the valves VB1 and VB
B2 is closed, the supply of the reaction gas is stopped, and the vacuum pump VP
The pressure inside the reaction tube 11 is again reduced to 4 to 5 × 10 ⁻³ Torr.

Subsequently, the main valve MV is closed, the valves VB3 and VB4 are opened, and nitrogen gas is supplied from the nitrogen gas sources 36 and 46 into the reaction tube 11, so that the inside of the reaction tube 11 is at normal pressure (atmospheric pressure). Return to Here, all valves VB1 to VB
B4, MV, SV, SSV are closed and left to cool for a predetermined time, for example, 15 minutes.

Thereafter, the sub-valve SSV is opened, and the pressure (atmospheric pressure) in the reaction tube 11 is passed through the needle valve NV.
-5~-70mmH ₂ O with respect to, preferably, -10
While sucking the gas in the reaction tube 11 with a pressure difference of about −50 mmH ₂ O, the lifting mechanism 54 is driven to lower the wafer boat 14 from the reaction tube 11 and unload the wafer boat 14 as shown in FIG. Then, the semiconductor substrate 15 is brought into a transportable state.

When the wafer boat 14 is unloaded, NH ₄ Cl adhering to a low-temperature portion of the reaction tube 11 sublimates when the heat-treated high-temperature semiconductor substrate 15 passes through the vicinity,
The sublimation gas may react with moisture in the atmosphere to generate particles. However, by employing such an unloading method, sublimation gas and particles are gently sucked and discharged without adhering to the semiconductor substrate 15, as schematically shown in FIG.

As described above, according to this embodiment, during the loading operation and the unloading operation of the semiconductor substrate 15, the gas in the reaction tube 11 is brought to -5 to -5 with respect to the atmospheric pressure.
70mmH ₂ O, preferably, gently evacuated at a pressure differential of -10 to-50 mm H about ₂ O. Therefore, the sublimation gas of the reaction by-products and the particles due to the sublimation gas, and further the particles of the reaction by-products and the general particles are exhausted, and these are adsorbed on the semiconductor substrate 15 and impair the film formation. Can be prevented.

Further, since the sub bypass pipe 65 is formed separately from the slow exhaust bypass pipe 64, the exhaust during loading / unloading, the slow exhaust, and the main exhaust can be performed using the vacuum pump VP. .

The present invention is not limited to the above embodiment, and various modifications and applications are possible. For example, in the above-described embodiment, a part of the bypass pipe 64 and a part of the sub-bypass pipe 65 are shared, but the bypass pipe 64 and the sub-bypass pipe 65 may be completely separated. In the above embodiment, the on-off valve SSV and the needle valve NV are arranged in series in the sub-bypass pipe 65. However, if the opening and closing and the opening can be appropriately controlled by feedback control or the like, only the needle valve NV is used. It may be arranged.

In the above embodiment, the bypass pipe 6
4 and the sub bypass pipe 65 are arranged so as to connect the exhaust pipes 63a and 63b. However, if the gas in the reaction pipe can be exhausted when loading and unloading the wafer boat 14, the bypass pipe 64 and the sub bypass pipe 65 are connected. Connection and arrangement can be arbitrarily changed. For example, as shown in FIG.
The bypass pipe 64 and the sub bypass pipe 65 are connected to the exhaust pipe 63
a and 63c may be arranged to connect. According to this configuration, the gas that has passed through the bypass pipe 64 and the sub-bypass pipe 65 does not pass through the trap TRP, the conductance of the flow path is high, and control of the flow rate is easy.

In the above embodiment, the sub-bar
Sub-viper with lube SSV and needle valve NV
By arranging the pipe 65 in parallel with the main valve MV,
Exhaust during loading / unloading of the wafer boat 14
Performed, but it is possible to use another configuration for this exhaust
It is. For example, as schematically shown in FIG.
Between valve VB5 and damper
A DAM is installed, which leads to the so-called factory exhaust 72,
An air line 71 may be provided. This exhaust line 71
Is connected to the damper DAM when the valve VB5 is turned on.
More relaxed, -5 to -70 mmH with respect to atmospheric pressure ₂O
The inside of the reaction tube 11 is evacuated by the pressure difference.

In this configuration, when the wafer boat 14 is loaded / unloaded, the main valve MV and the bypass valve (slow exhaust valve) SV are closed, and the valve V
B5 is opened and the gas in the reaction tube 11 is
5~-70mmH is evacuated at a pressure differential of about ₂ O. Therefore, as in the example schematically shown in FIG. 4, it is possible to prevent the sublimation gas and the particles of the reaction by-product from adhering to the semiconductor substrate 15.

In the above embodiment, the present invention has been described by taking the case of forming a silicon nitride film as an example. However, the present invention is not limited to the above embodiment, and various film forming processes and other processes can be performed. Applicable to The object to be processed is not limited to a semiconductor substrate or a wafer, and any object such as a glass substrate or a sapphire substrate can be an object to be processed.

[0044]

As described above, according to the present invention, the gas in the reaction tube is sucked at the time of loading and unloading to and from the reaction tube of the object to be treated, so that the particles and sublimation gas in the reaction tube are not treated. Adhere to the surface and do not form defects. In addition, since narrower piping is arranged in parallel with the slow exhaust pipe provided for slow exhaust and exhaust is performed,
There is no need to increase the burden on the equipment.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a film forming apparatus (semiconductor manufacturing apparatus) according to an embodiment of the present invention.

FIG. 2 is a view showing a state where a wafer boat for heat treatment is taken out of the film forming apparatus of FIG. 1;

FIG. 3 is a timing chart for explaining the operation of the film forming apparatus shown in FIGS. 1 and 2.

FIG. 4 is a view schematically showing a state in which particles in a reaction tube are exhausted.

FIG. 5 is a view showing a modification of the film forming apparatus of the present invention.

FIG. 6 is a view showing a modification of the film forming apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Reaction tube 12 Outer cylinder 13 Inner cylinder 14 Wafer boat 15 Semiconductor substrate 16 Heating heater 17 Manifold 31, 41 Gas supply pipe 35, 45 Gas source 51 Cover 54 Lifting mechanism 61 Exhaust pipe 63 Exhaust pipe 64 Bypass pipe 65 Sub-bypass tube

Continued on the front page F term (reference) 4K029 BA58 BD01 DA02 EA03 KA09 4K030 AA03 AA06 EA11 GA12 5F045 AA06 AB33 AC05 AC12 AD11 AD12 AE19 AF01 AF07 AF09 BB15 DP19 EB12 EG01 EG05

Claims (6)

[Claims] A reaction tube for accommodating a plurality of objects to be processed and performing a process; a loading mechanism for loading the objects to be processed into the reaction tube and unloading the processed objects; An exhaust passage connected to the reaction tube, for exhausting gas in the reaction tube; an exhaust unit connected to the exhaust passage, for exhausting gas in the reaction tube; A main valve for opening and closing an exhaust passage, a bypass passage for connecting the exhaust passages across the main valve and exhausting the gas in the reaction tube at a flow rate smaller than a gas flow rate of the exhaust passage, A bypass valve that is disposed in the bypass passage and opens and closes the bypass passage, and connects the exhaust passages across the main valve, and during the operation of loading or unloading the workpiece, A sub-bypass path for exhausting gas in the reaction tube at a flow rate smaller than the gas flow rate of the bypass path; and a sub-valve arranged in the sub-bypass path to open and close the sub-bypass path. An apparatus for processing an object to be processed, wherein the object to be processed is loaded or unloaded into the reaction tube by the loading mechanism while the sub-valve is opened and the gas in the reaction tube is exhausted by the exhaust means. 2. Opening the sub-valve and loading the object to be processed while exhausting the gas in the reaction tube by the exhaust means. After the loading is completed, open the sub-valve until the inside of the reaction tube reaches a first pressure. After the gas in the reaction tube is exhausted by the exhaust means, after the inside of the reaction tube reaches the first pressure, the bypass valve is opened, and the gas in the reaction tube is exhausted by the exhaust means. The gas to be processed according to claim 1, wherein after reaching a second pressure lower than the first pressure, the main valve is opened and the gas in the reaction tube is exhausted by the exhaust means. Body processing equipment. Wherein the exhaust means via the sub-valve in an open position, to exhaust gas in the reaction tube at a pressure differential of -5~-70mmH 2 _O relative to atmospheric pressure, characterized in that An apparatus for processing an object to be processed according to claim 1. 4. An apparatus for processing an object to be processed is a device for supplying an NH ₃ gas and a SiH ₂ Cl ₂ gas into the reaction tube to form a SiN film on the object to be processed. During the loading operation and / or the unloading operation, the sub-valve is opened and the exhaust unit exhausts gas to prevent the sublimation gas of NH ₄ Cl, which is a reaction by-product, from flowing to the object. 3. The processing apparatus for processing an object according to claim 1 or 2, wherein: 5. An object to be processed is loaded into a reaction tube, and a predetermined film forming process involving heat treatment is performed on the object to be loaded after loading.
In the method for processing an object to be unloaded, the object to be processed is loaded into the reaction tube and / or unloaded from the reaction tube while exhausting gas from the reaction tube. A method for processing an object to be processed. 6. The gas in the reaction tube is -5 to atmospheric pressure.
~-70mmH while exhausting at a pressure differential of 2 _O, processing of the workpiece according to claim 5, the workpiece is unloaded from and loaded into the reaction tube and / or the reaction tube, it is characterized by Method.