JPH04306824A - Heat treatment device - Google Patents

Abstract

PURPOSE:To make it possible to start a heat treatment in the state wherein the residual water vapor and oxygen in a heat treatment device are removed. CONSTITUTION:A load locking chamber 40, where inert gas is filled up and the material to be processed is carried in or out, is formed on the lower part of a heat treatment part 3 where a heat treatment is conducted on a plurality of materials 52 to be treated, and the water, vapor and the like remaining in the heat treatment part are removed by a vacuum exhaust system immediately before start of the heat treatment or after finish of the treatment.

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.

[Prior Art] Generally, in a heat treatment apparatus, such as an oxidation diffusion apparatus, the oxidation diffusion reaction is carried out at a higher temperature, for example, 1200° C., than in a film forming process by CVD or the like. If a metal material is used in the exposed interior of the furnace, and if a corrosive gas is used as a processing gas, there is a risk that the metal material will corrode and the products will adhere to and diffuse onto the semiconductor wafer, resulting in performance deterioration. Therefore, the entire processing container is made of heat-resistant and corrosion-resistant quartz or the like, which is integrally molded into a single-layer structure or a double-layer structure. The inlet pipe for the processing gas and the exhaust pipe for discharging the processed gas are integrally attached to the quartz processing container itself, and are heated at normal pressure, for example at 1200° C., while supplying water vapor etc. into the processing container. The apparatus is configured to oxidize a semiconductor wafer.

0002

[Problem to be solved by the invention] By the way, in recent years, LS
Due to the high integration of I, for example, the mounting density of MOSFET has improved, and in recent LSIs, for example, 1M, 4M DRA
The minimum design width of M has become less than 1 mm, and the thickness of the gate oxide film has also become less than 200 Å. Furthermore, 16MDRAM
The gate oxide film is becoming thinner to 100 to 150 Å. When the silicon surface is wet cleaned with HF or HCL as a pretreatment before film formation, a clean silicon surface appears immediately after cleaning, but soon the silicon reacts with oxygen and moisture in the air and the silicon surface becomes about 10 Å thick. A natural oxide film is formed. In addition, in the case of a horizontal furnace, when loading a boat carrying semiconductor wafers into a reaction tube heated to 1000°C by horizontal drive, convection due to the temperature difference between the inside and outside of the furnace causes It was inevitable that air would enter the reaction tube. Therefore, in the case of a horizontal furnace, the heated wafer reacts with oxygen in the air when loading the wafer, and the
The formation of a native oxide film of 0.00 Å is unavoidable, and since the native oxide film is porous and has poor film quality, there is a limit to its ability to handle high-density devices that require control of the gate oxide film due to its structure. .

On the other hand, in the case of a vertical furnace, less oxygen is entrained than in a horizontal furnace, and the formation of a natural oxide film is also less
Since the film thickness is as small as 50 Å, this vertical furnace is currently the main type of equipment used for film formation of 1M DRAM. However, as the density increases further to 4M and 16M, even in the case of this vertical furnace, the formation of a natural oxide film that occurs due to the insertion of air during loading and unloading and the adsorption of moisture on the wafers is suppressed. In particular, as the density of devices rapidly increases and the control of oxide film thickness becomes more precise, oxygen and moisture in the air will be reduced between the wafer cleaning and transport to the heat treatment furnace. It has become necessary to suppress the formation of a native oxide film of about 10 Å, which is formed by the reaction between silicon and silicon, or to eliminate residual moisture and oxygen in the heat treatment furnace, which are factors in the formation of the natural oxide film. In addition, even in processing equipment other than oxide film deposition equipment, it is necessary to suppress the formation of excess natural oxide film during film formation, especially for polysilicon film formation and capacitance, which require low contact resistance. be. The present invention has been devised to effectively solve the above-mentioned problems, and an object of the present invention is to suppress the formation of a natural oxide film during loading of a wafer into a heat treatment section. The purpose of the present invention is to provide a heat treatment apparatus that can perform the following steps.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the first invention provides a heat treatment section that performs predetermined heat treatment on a plurality of objects to be processed housed in a processing boat, and an interior of the heat treatment section. and a load lock chamber that is connected to the heat treatment section so as to be openable and closable, is filled with an inert gas, and carries the object to be processed into and out of the heat treatment section. This is how it was done. In order to solve the above-mentioned problems, the second invention includes a heat treatment section that performs predetermined heat treatment on a plurality of objects to be processed housed in a processing boat, and a manifold connected to an opening of the heat treatment section. , which is connected to the manifold and includes an evacuation system for evacuating the inside of the heat treatment section, and a cooling means for cooling the entire manifold.

[0005]

[Operation] According to the first invention, when the heat treatment, for example, oxidation treatment, of the object to be treated is completed in the heat treatment section, the vacuum exhaust system is driven to remove water vapor, which is a cause of the formation of a natural oxide film remaining in the heat treatment section. Eliminate oxygen components. Then, inert gas,
For example, the internal atmosphere is replaced with nitrogen (N2) to bring the pressure to normal pressure. Next, the processed object is unloaded into the load lock chamber which is already maintained at normal pressure with inert gas. At this time, the inside of the heat treatment section and the load lock chamber communicate with each other, but since the water vapor and oxygen components in the heat treatment section have already been removed, they do not flow into the load lock chamber. According to the second invention, the object to be processed is loaded into the heat treatment section and is evacuated to remove water vapor and oxygen components inside. When performing heat treatment, for example, oxidation diffusion treatment, on the object to be treated in the heat treatment section, in order to prevent the metal manifold from becoming high temperature and being corroded by corrosive gas,
The entire manifold is cooled by the cooling means. When the heat treatment operation is completed, the supply of the processing gas is stopped, and the vacuum exhaust system connected to the manifold is driven to eliminate residual water vapor, oxygen components, and the processing gas inside. Thereafter, the internal atmosphere is replaced with nitrogen to bring it to normal pressure, and the processed object is unloaded.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the 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 apparatus will be explained as an example of the heat treatment apparatus. As shown in FIGS. 1 and 2, this heat treatment apparatus includes a heat treatment section 1
The heat treatment section 1 has a cylindrical outer tube 2 made of, for example, quartz and has a ceiling, and is installed concentrically inside the outer tube 2 at a predetermined distance apart. The inner cylinder 3 is formed into a shape with an open upper end, and the processing container as a whole has a vertical double-tube structure. And, on the outer periphery of the outer cylinder 2,
A heater 4 is provided to surround this. A manifold 6 made of stainless steel, for example, is provided in the opening 5 at the lower end of the outer cylinder 2 and the inner cylinder 3.
are connected to each other and hold the outer cylinder 2 and inner cylinder 3. Specifically, an annular flange 7 is formed at the lower end of the outer cylinder 2, and a similar annular flange 8 is formed at the upper end of the manifold 6. The outer cylinder 2 and the manifold 6 are fixed by fixing them with bolts 10 via locking members 9. Furthermore, an O-ring 11 made of, for example, fluororubber is interposed between the contact surfaces of both the flange portions 7 and 8 to maintain sealing properties. Further, an elastic packing member 13 made of, for example, carbon fiber and having good thermal conductivity is interposed between the locking member 9 and the upper surface of the outer cylinder flange portion 7 in order to promote heat dissipation from the flange portion 7. has been done. Further, an annular convex portion 14 is provided on the inner wall of the manifold 6.
is formed, and the lower end of the inner tube 3 is supported and fixed to this annular convex portion 14. A gas introduction pipe 18 made of quartz, for example, is provided on the upper side wall of the manifold 6.
is provided so as to penetrate therethrough, and is arranged with its tip upright between the outer cylinder 2 and the inner cylinder 3, and is configured so that the processing gas can be emitted from the ejection hole 20 provided at the upper end. There is. Further, the gas introduction pipe 18 is connected to a combustion device 21 that combusts an inert gas supply source such as nitrogen or a processing gas supply source, for example, oxygen and hydrogen to generate water vapor when performing oxidation treatment. There is. Further, at the lower part of the gas introduction pipe 18, a relatively large diameter pipe, for example, a diameter of 60 m is provided.
m vacuum ports 23 are formed, and this vacuum port 2
3 is connected to a vacuum evacuation system 25 equipped with, for example, a turbo molecular pump.
It is constructed so that it can be evacuated to about r. In addition, in the manifold 6 opposite to the vacuum outlet 23,
An exhaust port 26 for exhausting the processing gas is formed, and an exhaust pipe 27 is connected to the exhaust port 26.
The processing system is configured to supply processed gas to the processing system. Furthermore, a temperature measuring jig 29 is inserted into the upper part of the exhaust port 26 to measure the temperature inside the processing container.

Further, the manifold 6 is provided with a cooling means 30 for cooling the entire manifold 6 during the oxidation diffusion treatment. Specifically, the cooling means 30 is constructed by forming the manifold 6 into a double pipe structure to form a cooling water passage 31 through which cooling water flows. An annular flange portion 33 is formed at the lower end of the manifold 6, and the annular flange portion 33 is connected to a base plate 34 made of stainless steel or the like, that is, an auxiliary member 35 to the upper wall side of the load lock chamber to be described later. It is supported and fixed by bolts 36 and 37 via. Since a load-lock chamber 40 that requires airtightness as described below is provided below this processing container, the space between the upper surface of the annular flange portion 33 and the auxiliary member 35, and this auxiliary member O-rings 41 and 42 are interposed at the contact portion between 35 and the base plate 34. On the other hand, a cap portion 45 made of, for example, stainless steel is provided at the lower end opening of the manifold 6 so as to be sealable via an O-ring 46 . This cap portion 45 has
Rotating shaft 4 made rotatable by a drive means (not shown)
7 is inserted through the rotary shaft 47, and a heat insulating cylinder 50 made of, for example, quartz is attached to the upper end of the rotating shaft 47. A wafer boat 51 as a processing boat made of quartz, for example, is placed on top of this heat-insulating cylinder 50, and
In this wafer boat 51, objects to be processed, such as a large number of semiconductor wafers 52, are stacked at a predetermined pitch. The cap portion 45 is configured to be able to be raised and lowered integrally with the heat insulating cylinder 50 and the wafer boat 51 by a boat elevator 54 provided below.

On the other hand, the lower part of the heat treatment section 1 is filled with an inert gas such as nitrogen, and is formed into a rectangular parallelepiped made of stainless steel, for example, and is used to transport the semiconductor wafers 52 into and out of the heat treatment section 1. A load-lock chamber 40 having an airtight structure is provided through an opening 80. The entire boat elevator 54 is housed in the load lock chamber 40, 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 a is an inert gas pipe 6 with a valve etc.
0 is connected, and the other end of this inert gas 60 is connected to an inert gas supply source 61. Further, an exhaust port 63 having a relatively large diameter is formed in the same side wall of the load lock chamber 40, and a pressure switch 66 is connected to the exhaust port 63.
4a and an exhaust pipe 65 equipped with a pressure gauge 64b are connected, and the other end of this exhaust pipe 65 is connected to an exhaust system 66 equipped with a turbo molecular pump, a dry pump, etc. Further, a maintenance door 67 is attached to the other side wall of the load lock chamber 40 so that it can be opened and closed when maintenance is performed inside the chamber. A robot chamber 71 that is airtightly connected to the load lock chamber 40 is connected to the load lock chamber 40 through a gate vent 70. A transfer device (not shown) for transferring semiconductor wafers is installed in the robot chamber 71. ) and a cleaning device (not shown) for removing a natural oxide film formed on the surface of a semiconductor wafer. A plurality of observation windows 73 made of glass or the like are formed on the side wall of the robot room 71 to observe the operating conditions inside.

A cassette chamber 76 which is made airtight is connected to the robot chamber 71 through a gate vent 75, and a cassette chamber (not shown) for storing a plurality of semiconductor wafers is connected through an opening/closing door 77. It is constructed so that it can be carried in and out. And the robot room 7
1 and the cassette chamber 76 are also connected to 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. next,
The operation of this embodiment configured as above will be explained. First, when performing oxidation diffusion treatment, the vacuum exhaust system 25 connected to the manifold 6 of the heat treatment equipment and the exhaust system 66 connected to the load lock chamber 40, robot chamber 71, and cassette chamber 76 are operated for a long time to vacuum the entire body. The vacuum state is, for example, 10-5 to 10-6 Torr. As a result, gases that cause the formation of a natural oxide film, such as moisture and enzyme components remaining in the processing container and in each of the chambers 40, 71, and 76, are almost certainly eliminated. When this removal is completed, nitrogen gas is then supplied into the processing container through the gas introduction pipe 18 to normal pressure, and the load lock chamber 40, robot chamber 71, and cassette chamber 7 are supplied from the inert gas supply source 61.
6, supply nitrogen gas to normal pressure. Once the internal pressure has reached normal pressure in this way, the cassette containing, for example, 25 semiconductor wafers is carried into the cassette chamber 76 through the opening/closing door 77 by a cassette carrying means (not shown). The semiconductor wafer in this cassette chamber 76 is stored in the robot chamber 7
After the native oxide film on the wafer surface is removed by cleaning, the wafers are sequentially stored in the 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 to accommodate it in the heat treatment section 1, and the cap section is 45 hermetically seals the lower end opening of the manifold 6. Since each process up to now has been carried out in a nitrogen atmosphere at normal pressure, no new natural oxide film is deposited on the semiconductor wafer. Moreover, once each process is completed, each chamber 40, 71,
Each gate vent 70, 75 is closed to prevent gas movement between the gate vents 76. As described above, when the semiconductor wafer 52 is housed in the heat treatment section 1, the heat treatment section is already heated to a predetermined temperature by the heater 4, for example, to about 1200° C. when performing oxidation diffusion. Then, water vapor is generated by burning hydrogen and oxygen in the combustion device 21, and this is supplied between the outer cylinder 2 and the inner cylinder 3 via the gas introduction pipe 18, while the pressure inside the processing container is is exhausted from the exhaust pipe 27 so as to maintain normal pressure,
Perform oxidation treatment. At this time, cooling water is passed through the cooling means 30 provided in the manifold 6 to cool the metal manifold 6 to below 100°C, preferably below 70°C,
Prevent this corrosion. In particular, even when a corrosive gas such as POCL3 is used in the diffusion process, the manifold 6 can be cooled to the temperature mentioned above, suppressing corrosion and eliminating particles that cause yield reduction. can be prevented from occurring. Further, at this time, if the cap portion 45 is also provided with a cooling means made of a water cooling jacket, further corrosion suppressing effects can be exhibited. Furthermore, if a quartz cover is provided all along the inner wall surface of the manifold 6, the temperature suppression effect will be further improved.

After the oxidation diffusion treatment has been carried out for a predetermined period of time as described above, the supply of water vapor from the gas introduction pipe 18 is stopped, and then the evacuation system 25 is driven again to vacuum the inside of the processing container as described above. Similarly, vacuum is drawn to 10-5 to 10-6 Torr and maintained for a predetermined period of time. As a result, water vapor components and oxygen components that cause a natural oxide film remaining in the processing container are almost completely eliminated. After the evacuation is completed in this manner, 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 carried out from the processing container. At this time, the load lock chamber 40 is at normal pressure in a nitrogen atmosphere, and the inside of the processing container and the load lock chamber 40 communicate through the lower end opening of the manifold 6. Since residual water vapor and the like have already been removed, water vapor components and the like will not flow into the load lock chamber 40. Thereafter, according to the operation procedure reverse to that described above, the processed semiconductor wafer is carried out via the robot chamber 71 and the cassette chamber 76, while a new unprocessed semiconductor wafer is carried in, and the same procedure as described above is carried out. The operating procedure will be repeated. In this way, according to this embodiment,
The inside of the heat treatment section 1 has a structure that can be evacuated, and a load lock chamber 40 filled with inert gas is provided below the heat treatment section 1 to remove water vapor components and oxygen components remaining in the reaction vessel before or after treatment to the outside. Therefore, the formation of a natural oxide film on the surface of the semiconductor wafer can be significantly suppressed. In addition, in the above embodiment, it was necessary to provide a metallic manifold 6 due to the need to evacuate the inside of the heat treatment section 1, but since a cooling means 30 for cooling the entire manifold was provided in this part, For example, even if corrosive gas is used during oxidation diffusion, the manifold 6
Therefore, it is possible to suppress the formation of a natural oxide film while suppressing the generation of particles that cause a decrease in yield.

Furthermore, since the inside of the container is evacuated, the sealing performance is improved by using the manifold 6, so the POC is improved compared to the conventional oxidation diffusion container constructed entirely of quartz.
Sealing performance against dangerous gases such as L3 can be improved, and safety can be improved. In addition, in the above embodiment, the manifold 6 is used to create a double tube structure in which the outer cylinder 2 and the inner cylinder 3 are separated and divided.
Compared to the heavy pipe structure, it is possible to significantly reduce costs. In the above embodiment, when the inside of the processing container is evacuated, the entire manifold 6 is heated by flowing high-temperature water through the cooling means 30 of the manifold 6, or by providing a heating means on the outer periphery of the manifold 6. If configured to do so, it is possible to further promote the discharge of residual water vapor, etc., and it is possible to shorten the discharge operation time or ensure the integrity of the discharge operation. Alternatively, the vacuum exhaust pipe and the exhaust pipe 27 for discharging the process gas may not be constructed separately, but may be integrated into one body, and both functions may be switched by operating a valve. Furthermore, the above embodiment can of course be applied to a normal oxidation diffusion device that does not draw a vacuum, and can also be applied to other devices other than the oxidation diffusion device, such as a CVD device.

[0013]

As described above, according to the present invention, it is possible to reliably eliminate water vapor components and oxygen components remaining in the heat treatment section, and to prevent water vapor components, etc. from flowing into the heat treatment section. The formation of a natural oxide film can be suppressed. Therefore, a uniform oxide film of good quality can be formed with high accuracy on the surface of the object to be processed, and it is possible to cope with the high integration of semiconductor products.

[Brief explanation of drawings]

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

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

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

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

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

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

[Explanation of symbols]

1 Heat treatment section 2 Outer cylinder 3 Inner cylinder 4 Heater 5 Opening 6 Manifold 21 Combustion device 23 Vacuum outlet 25 Vacuum exhaust system 27 Exhaust pipe 30 Cooling means 31 Cooling water passage 40 Load lock room 52 Semiconductor wafer (object to be processed)

Claims (2)

[Claims] 1. A heat treatment section that performs predetermined heat treatment on a plurality of objects to be processed housed in a processing boat, an evacuation system for evacuating the inside of the heat treatment section, and an openable/closable connection to the heat treatment section. A heat treatment apparatus comprising: a load lock chamber filled with an inert gas, and a load lock chamber for transporting the object to be processed into and out of the heat treatment section. 2. A heat treatment section that performs predetermined heat treatment on a plurality of objects to be processed housed in a processing boat; a manifold connected to an opening of the heat treatment section; A heat treatment apparatus comprising: an evacuation system for evacuating the manifold; and a cooling means for cooling the entire manifold.