JP3181308B2 - 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.

2. Description of the Related Art Generally, in a heat treatment apparatus, for example, an oxidation diffusion apparatus, an oxidation diffusion reaction is performed at a higher temperature, for example, 1200 ° C. than a film forming process by CVD or the like. If a metal material is used in the exposed part of the furnace, if a corrosive gas is used as the processing gas, the metal material may corrode and the product may adhere to and diffuse on the semiconductor wafer, resulting in deterioration of performance. Therefore, the entire processing container is made of heat-resistant and corrosion-resistant quartz or the like integrally formed in a single structure or a double structure. The introduction pipe for the processing gas and the exhaust pipe for discharging the processed gas are integrally attached to the quartz processing container itself, and at a normal pressure, for example, at 1200 ° C. while supplying steam or the like into the processing container. The semiconductor wafer is configured to be oxidized.

[0002]

By the way, in recent years, LS
As the degree of integration of I increases, for example, the mounting density of MOSFETs increases.
The minimum design width of M has become 1 mm or less, and the thickness of the gate oxide film has also become 200 ° or less. In addition, 16MDRAM
Has a tendency to be further reduced to 100 to 150 °. If the silicon surface was wet cleaned with HF and HC l as pretreatment before the deposition, but right after washing appears a clean silicon surface, 10 Å on the silicon surface immediately react oxygen and moisture and silicon in air The front and rear natural oxide films are formed. In the case of a horizontal furnace, when a boat loaded with semiconductor wafers is loaded into a reaction tube heated to, for example, 1000 ° C. by driving in a horizontal direction, convection caused by a temperature difference between the inside of the furnace and the outside of the furnace causes It was inevitable that air would enter the inside of the reaction tube.
Therefore, in the case of a horizontal furnace, the heated wafer reacts with oxygen in the air when the wafer is loaded, and 50 to 50 mm.
The formation of a natural oxide film of 100 ° is unavoidable, and the natural oxide film is porous and has poor film quality, so that there is a natural limit to a high-density element that requires control of the gate oxide film due to its structural reason. .

On the other hand, in the case of a vertical furnace, the entrapment of oxygen is small and the formation of a natural oxide film is reduced by 30 to 30 hours as compared with a horizontal furnace.
This vertical furnace is the mainstream apparatus used for film formation of the current 1M DRAM because it is as small as 50 °. However, 4M, the 16M further densification promoting, loading in the case of the vertical furnace, insertion of the air at the time of unloading, and the formation of native oxide film generated due to absorption landing portion of the wafer Improvements that need to be suppressed are needed, especially when the density of devices is rapidly increasing and the control of the oxide film thickness is becoming more and more precise. It has become necessary to suppress the formation of a natural oxide film of about 10 ° formed by the reaction of moisture and silicon, or to remove residual moisture and oxygen remaining in the heat treatment furnace, which cause formation of the natural oxide film. In addition, even in a processing apparatus other than an oxide film forming apparatus, it is necessary to suppress the formation of a polysilicon film and a capacitance, which require a particularly low contact resistance, and the generation of an extra natural oxide film even when the film is formed. is there. The present invention has been made in view of the above problems, and has been made in order to effectively solve the problems. An object of the present invention is to suppress the formation of a natural oxide film at the time of loading a wafer into a heat treatment section. Can be with manifold erosion and manifold bottom opening
It is an object of the present invention to provide a heat treatment apparatus capable of preventing corrosion of a cap part for opening and closing a part .

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a vertical heat treatment section for performing a predetermined heat treatment on a plurality of workpieces housed in a processing boat; A manifold connected to the opening of the unit, a vacuum exhaust system connected to the manifold and for evacuating the inside of the heat treatment unit, cooling means for cooling the entire manifold, lower end
A load lock chamber connected via an opening, filled with an inert gas therein, and configured to carry the object into and out of the heat treatment unit, and a lower end opening of the manifold.
It has a cap that can be moved up and down to open and close.
A cooling means for cooling the cap is provided in the cap.
Those who like to be.

[0005]

According to the present invention, heat treatment of the workpiece in the heat treatment section, for example, oxidation processing is completed is a main cause of a natural oxide film formed remaining in the heat treated portion by driving the vacuum evacuation system water vapor, oxygen component To eliminate. Thereafter, the internal atmosphere is replaced with an inert gas, for example, nitrogen (N ₂ ), and the pressure is adjusted to normal pressure. Next, the processed object is unloaded into the load lock chamber already maintained at normal pressure by the inert gas.
At this time, the interior of the heat treatment section communicates with the load lock chamber,
Since the water vapor and oxygen components in the heat treatment section have already been eliminated, they do not flow into the load lock chamber.
In addition , the object to be processed is evacuated while being loaded into the heat treatment section, thereby removing water vapor and oxygen components therein. When performing a heat treatment, for example, an oxidative diffusion treatment on the object to be processed in the heat treatment unit,
In order to prevent the metallic manifold from becoming hot and being corroded by corrosive gas, the entire manifold is cooled by cooling means. Then, when the heat treatment operation is completed, the supply of the processing gas is stopped, the vacuum exhaust system connected to the manifold is driven, and the residual water vapor inside,
Eliminates oxygen components and processing gases. Thereafter, the internal atmosphere is replaced with nitrogen to make the pressure normal, and the processed object is unloaded. Open and close the lower end opening of the manifold
Cooling means is also provided in the cap part to cool it
The cap is corroded by corrosive gas
Can be prevented.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a heat treatment section according to the present invention will be described below in detail with reference to the accompanying drawings. In this embodiment, an oxidation diffusion device will be described as an example of the heat treatment device. As shown in FIG. 1 and FIG.
The heat treatment unit 1 is formed in a cylindrical shape with quartz, for example, and has a ceiling portion. The outer tube 2 is concentrically installed inside the outer case 2 with a predetermined distance therebetween. And an inner cylinder 3 having an open upper end, and constitutes a processing container having a vertical double-tube structure as a whole. And, on the outer circumference of the outer cylinder 2,
A heater 4 is provided so as to surround this.
An opening 6 at the lower end of the outer cylinder 2 and the inner cylinder 3 is provided with a manifold 6 made of, for example, stainless steel.
Are connected, and hold the outer cylinder 2 and the inner cylinder 3. Specifically, an annular flange portion 7 is formed at a lower end portion of the outer cylinder 2, and a similar annular flange portion 8 is also formed at an upper end portion of the manifold 6. The outer cylinder 2 and the manifold 6 are fixed by fixing the nut 8 with a bolt 10 via a locking member 9. Further, an O-ring 11 made of, for example, fluoro rubber is interposed between the contact surfaces of the flange portions 7 and 8 to maintain a sealing property. Further, an elastic packing member 13 made of, for example, carbon fiber having good thermal conductivity is provided between the locking member 9 and the upper surface of the outer cylinder flange portion 7 to promote heat radiation of the flange portion 7. Have been. In addition, an annular convex portion 14 is provided on the inner wall of the manifold 6.
The lower end of the inner cylinder 3 is supported and fixed to the annular projection 14. A gas introduction pipe 18 made of, for example, quartz is provided on an upper side wall of the manifold 6.
Is provided between the outer cylinder 2 and the inner cylinder 3 with its leading end standing upright so that the processing gas can be released from the ejection hole 20 provided at the upper end. I have. In addition, an inert gas supply source such as nitrogen or a processing gas supply source, for example, a combustion device 21 for burning oxygen and hydrogen to generate steam by performing oxidation treatment is connected to the gas introduction pipe 18. I have. Further, a relatively large diameter, for example, a diameter of 60 m, is provided below the gas introduction pipe 18.
m vacuum evacuation port 23 is formed, and this vacuum evacuation port 2 is formed.
3, for example an evacuation system 25 with a turbo-molecular pump is connected, in the container for example 10 ^-6 Torr
It is configured so that it can be evacuated to the extent. Also,
An exhaust port 26 for exhausting a processing gas is formed in the manifold 6 at a portion opposite to the vacuum port 23, and an exhaust pipe 27 is connected to the exhaust port 26.
It is configured to supply the processed gas to the processing system. Further, a temperature measurement jig 29 for measuring the temperature inside the processing container is inserted above the exhaust port 26.

The manifold 6 is provided with a cooling means 30 for cooling the entire manifold 6 during the oxidation diffusion process. Specifically, the cooling means 30 is configured by forming a cooling water passage 31 through which cooling water flows by making the manifold 6 have a double pipe structure. An annular flange portion 33 is formed at a lower end portion of the manifold 6. The annular flange portion 33 is attached to a base plate 34 made of, for example, stainless steel or the like, that is, an auxiliary member 35 to an upper wall side of a load lock chamber described later. And are fixedly supported by bolts 36 and 37. Since a load lock chamber 40 that requires airtightness is provided below the processing container as described later, the load lock chamber 40 is provided between the upper surface of the annular flange portion 33 and the auxiliary member 35 and the auxiliary member 35. O-rings 41 and 42 are provided at contact portions between the base plate 34 and the base plate 34. On the other hand, a cap 45 made of, for example, stainless steel is provided at the lower end opening of the manifold 6 via an O-ring 46 so as to be sealable. In this cap part 45,
Rotating shaft 4 rotatable by driving means (not shown)
7 is inserted, and a heat retaining cylinder 50 made of, for example, quartz is attached to the upper end of the rotating shaft 47. Then, a wafer boat 51 as a processing boat made of, for example, quartz is placed on the heat retaining cylinder 50,
An object to be processed, for example, a large number of semiconductor wafers 52, is stacked in the wafer boat 51 at a predetermined pitch. Then, the cap section 45 is moved by the boat elevator 54 provided below the heat insulating cylinder 50 and the wafer boat 51.
It is configured to be able to move up and down as one unit.

On the other hand, an inert gas such as nitrogen is filled in the lower part of the heat treatment unit 1, and the semiconductor wafer 52 in the heat treatment unit 1 is loaded and unloaded. An airtight load lock chamber 40 is provided through the opening 100 . The load lock chamber 40 houses the entire boat elevator 54, and has a height that can accommodate at least the entire wafer boat 51. As shown in FIGS. 3 to 6, a gas supply port 59 for supplying an inert gas such as nitrogen is formed in the side wall of the load lock chamber 40, and the gas supply port 59 is provided in the middle thereof. Is connected to an inert gas pipe 60 via a valve or the like, and the other end of the inert gas 60 is connected to an inert gas supply source 61. The same side wall of the load lock chamber 40 is provided with a relatively large-diameter exhaust port 6.
The exhaust port 63 is connected to an exhaust pipe 65 having a pressure switch 64a and a pressure gauge 64b. The other end of the exhaust pipe 65 is provided with a turbo molecular pump, a dry pump, and the like. An exhaust system 66 is connected. On the other side wall of the load lock chamber 40, a maintenance door 67 that opens and closes when performing maintenance in the chamber is movably mounted. The load lock chamber 40 is connected to an airtight robot chamber 71 via a gate valve 70. In the robot chamber 71, a transfer device (not shown) for transferring a semiconductor wafer. And a cleaning device (not shown) for removing a natural oxide film formed on the surface of the semiconductor wafer.
A plurality of observation windows 73 made of glass or the like for observing the internal operation state are provided on the side wall of the robot room 71.
Are formed.

The robot room 71 has a gate.
A cassette chamber 76 which is airtightly connected via a valve 75 is connected, and is configured so that a cassette (not shown) for accommodating a plurality of semiconductor wafers can be loaded and unloaded via an opening / closing door 77. I have. And the robot room 71
Gas supply pipes 80 and 81 directly connected to the inert gas supply source 61 and exhaust pipes 83 and 84 connected to the exhaust system 66 are also connected to the cassette chamber 76. Next, the operation of the present embodiment configured as described above will be described. First, when performing the oxidation diffusion treatment, the vacuum exhaust system 25 connected to the manifold 6 of the heat treatment apparatus and the exhaust system 66 connected to the load lock chamber 40, the robot chamber 71, and the cassette chamber 76 are driven for a long time to evacuate the whole body. Then, a vacuum state of, for example, 10 ⁻⁵ to 10 ⁻⁶ Torr is established.
As a result, gases that form a natural oxide film, such as moisture and enzyme components, remaining in the processing container and the chambers 40, 71, and 76 are almost certainly eliminated. When the removal is completed, nitrogen gas is supplied to the processing vessel to normal pressure through the gas introduction pipe 18 and the load lock chamber 40, the robot chamber 71, and the cassette chamber 7 are supplied from the inert gas supply source 61.
6 is supplied with nitrogen gas to normal pressure. When the internal pressure becomes normal pressure in this way, a cassette containing, for example, 25 semiconductor wafers is loaded into the cassette chamber 76 via the opening / closing door 77 by cassette transport means (not shown).
The semiconductor wafer in the cassette chamber 76 is stored in the robot chamber 7.
After being held by a single-wafer transfer means (not shown) in 1 and removing a natural oxide film on the wafer surface by washing, the wafers are sequentially accommodated in a wafer boat 51 lowered into the load lock chamber 40.

After all the semiconductor wafers have been accommodated in the wafer boat 51 in this manner, the wafer boat 51 is then raised by the boat elevator 54 and accommodated in the heat treatment section 1 and the cap section By 45, the lower end opening of the manifold 6 is hermetically sealed. Since each of the steps so far is performed in a nitrogen atmosphere at normal pressure, a new natural oxide film does not adhere to the semiconductor wafer. When each process is completed, each chamber 40, 7
The gate valves 70 and 75 are closed to prevent gas movement between the gate valves 1 and 76. As described above, when the semiconductor wafer 52 is accommodated in the heat treatment unit 1, the heat treatment unit is already heated by the heater 4 to a predetermined temperature, for example, about 1200 ° C. when oxidative diffusion is performed. Then, steam is generated by burning hydrogen and oxygen in the combustion device 21, and this is supplied to the gas introduction pipe 18.
While supplying it between the outer cylinder 2 and the inner cylinder 3 through the exhaust pipe 27 so as to maintain the pressure in the processing vessel at the normal pressure, thereby performing the oxidation treatment. At this time, cooling water is circulated through cooling means 30 provided in the manifold 6 to cool the metallic manifold 6 to 100 ° C. or less, preferably 70 ° C. or less, thereby preventing this corrosion. In particular, even when a corrosive gas such as phosphorus oxychloride (POCl ₃ ) is used in the diffusion treatment, the manifold 6 can be cooled to the above-mentioned temperature, so that corrosion can be suppressed and the yield is reduced. Can be prevented from being generated. At this time, if a cooling means composed of a water-cooled jacket is also provided in the cap portion 45, a further corrosion suppressing effect can be exhibited. Further, if a quartz cover is provided on the entire surface along the inner wall surface of the manifold 6, the effect of suppressing corrosion is further improved.

After the oxidation diffusion treatment has been performed for a predetermined time as described above, the supply of water vapor from the gas introduction pipe 18 is stopped, and then the vacuum exhaust system 25 is driven again to evacuate the inside of the processing vessel. In the same manner as described above, the chamber is evacuated to 10 ^-5 to 10 ^-6 Torr and maintained for a predetermined time. Thereby, the water vapor component and the oxygen component which cause the natural oxide film remaining in the processing container are almost completely eliminated. When the removal is completed in this way, next, nitrogen, which is an inert gas, is supplied into the processing container to bring the internal pressure to normal pressure. Then, the wafer boat 51 is lowered by the boat elevator 54, and the processed semiconductor wafer 52 is unloaded from the processing container. At this time, the load lock chamber 40 is at a normal pressure in a nitrogen atmosphere, and the inside of the processing vessel and the load lock chamber 40 communicate with each other through the lower end opening of the manifold 6. Since the residual water vapor and the like have already been removed, the water vapor component and the like do not flow into the load lock chamber 40. Thereafter, the processed semiconductor wafers are transferred to the robot chamber 71 and the cassette chamber 7 by the reverse operation procedure described above.
While being unloaded outside through 6, a new unprocessed semiconductor wafer is loaded, and the same operation procedure as described above is repeated. As described above, according to the present embodiment, the inside of the heat treatment unit 1 has a structure capable of evacuating, and the load lock chamber 40 filled with an inert gas is provided below the heat treatment unit 1 to provide a reaction vessel before or after the treatment. Since the water vapor component and the oxygen component remaining inside are excluded to the outside, the formation of a natural oxide film on the surface of the semiconductor wafer can be greatly suppressed. In the above embodiment,
Since the inside of the heat treatment section 1 needs to be evacuated, a metallic manifold 6 needs to be provided. However, since a cooling means 30 for cooling the entire manifold is provided in this portion, for example, a corrosive gas is used during oxidation diffusion. However, corrosion of the manifold 6 can be prevented, and therefore, formation of a natural oxide film can be suppressed while suppressing generation of particles that cause a reduction in yield.

Furthermore, since the inside of the container is evacuated, the sealability is improved by using the manifold 6, so that the POC is compared with the conventional oxidized diffusion container made of all quartz.
It can improve the sealing against hazardous gases l ₃ etc., thereby improving the safety. Further, in the above embodiment, since the outer tube 2 and the inner tube 3 are divided and divided by using the manifold 6, the integral type 2 in the conventional oxidation diffusion device is used.
The cost can be significantly reduced as compared with the heavy pipe structure. In the above embodiment, when the inside of the processing vessel is evacuated, high-temperature water is supplied to the cooling means 30 of the manifold 6 or a heating means is provided on the outer periphery of the manifold 6 to heat the entire manifold 6 during evacuation. With such a configuration, the discharge of residual water vapor and the like can be further promoted, and the discharge operation time can be reduced or the integrity of the discharge operation can be secured. Further, the vacuum exhaust pipe and the exhaust pipe 27 for exhausting the processing gas may not be formed separately but may be integrated to switch between the two functions by a valve operation. Further, the above embodiment can be applied to a normal oxidation / diffusion apparatus without vacuuming, and can be applied to a CVD apparatus and the like other than the oxidation / diffusion apparatus.

[0013]

As described above, according to the present invention, the water vapor component and the oxygen component remaining in the heat treatment part can be reliably eliminated and the inflow of the water vapor component and the like into the heat treatment part can be prevented. Formation of a natural oxide film can be suppressed. Therefore, a uniform oxide film of good quality can be accurately formed on the surface of the object to be processed, and it is possible to cope with high integration of semiconductor products. Also, during heat treatment
The manifold is cooled by cooling the manifold with cooling means.
Prevents the manifold from being corroded by corrosive gases
Can be Furthermore, a cooling means for cooling the cap
Providing steps prevents corrosion of the cap.
Can be. Also, a quartz cover on the inner wall of the manifold
The corrosion suppression effect can be further improved by providing
You. When vacuuming after heat treatment,
If the heat is applied to the
Can promote outing.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a heat treatment apparatus according to the present invention.

FIG. 2 is an enlarged view showing a main part of a heat treatment apparatus according to the present invention.

FIG. 3 is a schematic view showing a load lock chamber side of the heat treatment apparatus according to the present invention.

FIG. 4 is a plan view showing a load lock chamber side used in the present invention.

FIG. 5 is a front view showing a load lock chamber side used in the present invention.

FIG. 6 is a side view showing a load lock chamber side used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat treatment part 2 Outer cylinder 3 Inner cylinder 4 Heater 5 Opening 6 Manifold 21 Combustion device 23 Vacuum inlet 25 Vacuum exhaust system 27 Exhaust pipe 30 Cooling means 31 Cooling water passage 40 Load lock chamber 52 Semiconductor wafer (workpiece)

──────────────────────────────────────────────────の Continued on the front page (58) Field 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 (5)

(57) [Claims] 1. A vertical heat treatment section for performing a predetermined heat treatment on a plurality of objects to be processed accommodated in a processing boat, a manifold connected to an opening of the heat treatment section, and a manifold connected to the manifold; A vacuum evacuation system for evacuating the inside of the heat treatment section, cooling means for cooling the entire manifold, and being connected to the heat treatment section via a lower end opening of the manifold and being inert therein. together with the gas is filled, a load lock chamber for loading and unloading the object to be processed to the heat treatment unit, lift-friendly in order to open and close the lower end opening of the manifold
And a cap portion provided with
A heat treatment apparatus comprising a cooling means for cooling the heat treatment apparatus. 2. The cooling means for cooling the entire manifold comprises a cooling water passage formed by forming the manifold into a double pipe structure. Heat treatment equipment. 3. The manifold is provided with a quartz cover along the inner wall surface.
Or the heat treatment apparatus according to 2 . 4. The cooling means is characterized in that high-temperature water flows when the heat treatment unit is evacuated after the heat treatment apparatus is completed, thereby facilitating the discharge of residual water vapor. Item 4. The heat treatment apparatus according to any one of Items 1 to 3 . 5. The system according to claim 1, wherein said manifold is provided with a heating means which is driven when said heat treatment apparatus is completed and said heat treatment section is evacuated to promote discharge of residual water vapor. The heat treatment apparatus according to any one of claims 1 to 3 .