JP3617575B2 - Vacuum exhaust system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an evacuation system used to evacuate a vacuum chamber for semiconductor manufacturing, for example.
[0002]
[Prior art]
A conventional evacuation system will be described with reference to FIG.
The vacuum chamber 10 is a process chamber of a semiconductor manufacturing apparatus such as an etching apparatus or a chemical vapor deposition apparatus (CVD), for example, and the vacuum chamber 10 is connected to a vacuum pump 12 through a pipe 14. The vacuum pump 12 is used for increasing the pressure of the process gas from the vacuum chamber 10 to atmospheric pressure. Conventionally, an oil rotary pump and a dry pump are mainly used.
[0003]
When the degree of vacuum required by the vacuum chamber 10 is higher than the ultimate degree of vacuum of the dry pump 12, an ultra-high vacuum pump such as a turbo molecular pump may be further provided upstream of the dry pump. Since the process gas is toxic or explosive depending on the type of process, an exhaust gas treatment device 22 is disposed downstream of the vacuum pump 12. Among the process gases whose pressure has been increased to the atmospheric pressure, those which cannot be released into the atmosphere as described above are subjected to treatments such as adsorption, decomposition and absorption, and only harmless gases are released. The pipe 14 is provided with a valve at an appropriate position as necessary.
[0004]
[Problems to be solved by the invention]
The conventional vacuum exhaust system as described above has the following disadvantages: (1) If the process gas or reaction by-product gas is corrosive, the gas will corrode the vacuum pump, There is a disadvantage that the lifetime is shortened.
For example, in the case of etching Si, when CF ₄ and O ₂ which are typical process gases are used, SiF ₄ , F ₂ , CO, and CO ₂ together with the residual gas of CF ₄ and O ₂ from the process chamber. By-products are discharged by a vacuum pump. Of these, F ₂ is particularly corrosive (contains F radicals for process reasons) and corrodes the vacuum pump.
[0005]
(2) Also, if there is a substance with a high sublimation temperature in the reaction by-product, the gas is exhausted by the vacuum pump, so the gas solidifies during the pressurization and precipitates in the vacuum pump, causing a failure. Become.
For example, when BCl ₃ and Cl ₂ , which are typical process gases, are used to etch aluminum, the process gas from the process chamber is a residual gas of BCl ₃ and Cl ₂ and a reaction byproduct of AlCl ₃ . Is evacuated by a vacuum pump. This AlCl ₃ does not precipitate because the partial pressure is low on the intake side, but the partial pressure increases during pressurized exhaust, and precipitates in the vacuum pump, causing a failure of the vacuum pump. The same applies to reaction by-products such as (NH ₄ ) ₂ SiF ₆ and NH ₄ Cl produced from a CVD apparatus for forming a SiN film.
[0006]
{Circle around (3)} Further, when a reactive gas is contained in the reaction by-product at a high temperature, the gas reacts in the vacuum pump, causing a failure of the vacuum pump.
For example, when a typical process gas WF ₆ or SiH ₄ is used in a plasma CVD apparatus for forming a tungsten film, a residual gas of WF ₆ or SiH _{4 and} a by-product of HF and H ₂ are generated from the process chamber. Is discharged. As pressure and temperature rise in the vacuum pump, WF ₆ and SiH ₄ react to precipitate W, which causes a failure of the vacuum pump.
[0007]
(4) Since the trapped process gas is discarded without being reused, the running cost is high. In particular, a gas such as SiH ₄ is expensive and desirably reused. However, in the conventional method, since a plurality of kinds of gases are mixed in the trap, a lot of labor is required for the separation work.
[0008]
(5) Since all gases are introduced into the exhaust gas treatment apparatus for treatment, the scale of the treatment apparatus becomes large, enormous equipment costs are required, the treatment process becomes complicated, and the running cost increases.
[0009]
Of these, (1) is the development of a corrosion-resistant vacuum pump, and (2) is not deposited by raising the temperature of the vacuum pump or injecting an inert gas into the pump to lower the partial pressure. Although such measures are taken, these improvement measures are improvements only on the side of the vacuum pump, and are not considered as the entire vacuum exhaust system, and thus are not sufficiently effective. Further, (4) and (5) are not even considered at all.
[0010]
The present invention has been made in view of the above drawbacks, and a vacuum capable of improving operational reliability and reducing equipment and operating costs by extending the life of a vacuum pump and reducing the capacity of an exhaust gas treatment device. It aims to provide an exhaust system.
[0011]
[Means for Solving the Problems]
In the present invention, a sacrificial material that reacts with a predetermined active component of the exhaust gas from the process chamber and inactivates it is disposed in an exhaust pipe that communicates the process chamber with a vacuum pump for exhausting the chamber. An evacuation system characterized in that a reaction trap is provided.
As a result, the active component present in the exhaust gas reacts with the sacrificial material before flowing into the vacuum pump and is converted into a more inert substance, so that this component corrodes the vacuum pump or other components in the vacuum pump. This prevents the occurrence of clogging by reacting with other ingredients.
[0012]
Then, the sacrificial material is formed with a breathable, the sacrificial material having a vent temper is characterized in that it is arranged so as to close the flow path of the exhaust pipe. In this case, since the sacrificial material is disposed on the upstream side of the vacuum pump and the gas flow rate is large, it is necessary to increase the air permeability to some extent.
[0013]
Then, between the sacrificial material and the vacuum pump, in which a product by the reaction of the predetermined active ingredient and the sacrificial material, characterized in that a removing mechanism for removing from the flue gas. Thereby, the product due to the reaction with the sacrificial material is removed before reaching the vacuum pump, so that the vacuum pump is kept clean.
Further, the vacuum exhaust system, the removal mechanism is characterized in that a cold trap. Thereby, the reaction product having a relatively high freezing point is condensed and trapped and removed.
[0014]
Further, the vacuum pump is preferably the exhaust path is a dry pump using no lubricant. In such a vacuum pump, since the constituent members are not covered with the lubricating oil and exposed, the present invention is particularly useful because it is easily affected by the corrosive components contained in the exhaust gas.
[0015]
Moreover , it is preferable that the reaction trap is detachably attached to the exhaust pipe . This makes it easy to replace the reaction trap, and the sacrificial material can be replenished with the reaction trap removed from the exhaust pipe.
[0016]
Further, it is preferable that the reaction trap is connected in a conducting the two systems in parallel and selectively to the exhaust pipe, by using switching this, the exhaust line work replenishment or replacement of the sacrificial material This can be done without stopping.
[0017]
In addition , a sensor for measuring the differential pressure before and after the reaction trap is preferably provided, and by the instruction of this sensor, it is possible to determine the degree of reduction of the sacrificial material in the reaction trap or the state of clogging. it can.
[0018]
Further, the sacrificial material is C, Si, is preferably one containing at least one of the group consisting of S, it is preferred that the sacrificial material is a metal.
[0019]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a basic embodiment related to the present invention , and a reaction trap 16 is provided via valves 18 and 20 in an exhaust pipe 14 connecting a vacuum chamber 10 and a vacuum pump 12. An exhaust gas treatment device 22 is provided on the downstream side of the vacuum pump 12.
[0020]
As shown in FIG. 2, the reaction trap 16 is configured such that a container 28 for storing a sacrificial material 26 is provided inside a cylindrical casing 24, and an inlet 32 is provided in a top plate 30. An outlet 34 is provided on the outer surface. As shown in FIG. 3 (a), the container 28 includes two tubes 36 and 38 made of a mesh-like material so as to have air permeability, and a top plate 40 that covers the upper surface of the space between them. The bottom plate 42 covers the entire lower side of the container.
[0021]
The sacrificial material 26 is also formed in the form of particles, powders, needles, irregular lumps, fibers, or sintered bodies so as to have air permeability. The material of the sacrificial material is selected so that it is highly reactive with the component to be treated in the exhaust gas and is stable and easy to process. A problem in the semiconductor manufacturing process is that the gas to be treated often contains fluorine. In this case, C, Si, S, or a mixture thereof may be used. A metal that is the same as or similar to the material constituting the vacuum pump is useful as a sacrificial material.
[0022]
The inlet 32 and the outlet 34 are respectively provided with flanges 44 and 46 for connecting exhaust pipes. The inlet 32 communicates with the inner space of the container 28, which is connected to the vacuum chamber 10 via the valve 18. It is connected to the. Further, the outer space of the container 28, that is, the inner space of the casing 24, communicates with the outflow port 34, which is connected to the vacuum pump 12 via the valve 20. In addition, the top plate 30 of the casing 24 can be removed, thereby facilitating replenishment and replacement of the sacrificial material 26 or cleaning the inside of the casing 24.
[0023]
FIGS. 3B and 3C show another example of a container for storing the sacrificial material 26. FIG. 3B shows that the inner cylinder 38 is shortened and the bottom portions 48 and 50 are also made of mesh. . Therefore, the area of venting the container 28 is large, the reaction efficiency is high, even small pressure loss. In FIG. 3 (c), the upper part of the outer cylinder 36 is formed by a non-breathable cylinder plate 52 so that the gas flows only on the lower side. Thereby, when the sacrificial material 26 is lost from the container due to the reaction with the exhaust gas, the sacrificial material in the upper part of the container 28 is lowered and sequentially supplied to the lower part, and the reaction is continued.
[0024]
FIG. 4 shows another embodiment in which a taper portion 54 having a narrow lower side is provided at the lower portion of the casing 24. In the case where a solid product is produced by the reaction between the sacrificial material 26 and the exhaust gas, the product is dropped on the tapered portion 54 and appropriately discharged from the lower discharge port 56. In this case, in order to improve the product capture rate, it is preferable to use a downward flow of gas, and therefore it is advantageous to combine with a sacrificial material container 28 of the type of FIG.
[0025]
FIG. 5A shows still another embodiment, in which a sacrificial material 62 formed in a plate shape so as to have air permeability is attached to the inside of a cylindrical casing 60. This plate-shaped sacrificial material 62 is a layered or layered mesh-shaped material, a material obtained by sintering a granular, powdered, needle or rod-shaped member, a material in which a hole is formed in the plate-shaped member, etc. However, it can be appropriately selected depending on the situation. FIG. 5B shows a plate-like sacrificial material 62 arranged in a layered manner with a gap 64 serving as a gas flow path formed therebetween. This is suitably used when the above processing is difficult.
[0026]
Figure 6 is a basic embodiment of the invention, is provided with a cold trap 70, 72 downstream of the embodiment of FIG. As a result, products formed by the reaction of the components in the exhaust gas with the sacrificial material and / or components remaining without reacting with the sacrificial material are removed before the vacuum pump 12. In this example, since two traps 70 and 72 having different temperatures are provided, elements having different freezing points can be separated and trapped, which is convenient when used by regenerating.
[0027]
FIG. 7 shows another embodiment. By providing two reaction traps 16 each having valves 18 and 20, the reaction trap 16 can be replaced and the sacrificial material can be replenished without stopping the exhaust line. It is what I did. Further, a differential pressure sensor 7 4 before and after the reaction trap 16 in this example is provided by an instruction of the sensor 74, decreases the degree and sacrificial material in the reaction trap, or the like so as to be able to determine the clogging state It has become.
[0028]
【The invention's effect】
As described above, according to the present invention, the active component present in the exhaust gas reacts with the sacrificial material before it flows into the vacuum pump and is converted into a more inert substance. Can be prevented from clogging or clogging by reacting with other components in the vacuum pump. Therefore, by extending the life of the vacuum pump and saving the capacity of the exhaust gas treatment device, it is possible to improve operation reliability and reduce equipment and operating costs.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of an evacuation system according to an embodiment related to the present invention.
FIG. 2 is a diagram showing a specific configuration of a reaction trap which is a main part of the present invention.
FIG. 3 is a diagram showing a configuration example of a sacrificial material container.
FIG. 4 is a diagram showing another embodiment of a reaction trap.
FIG. 5 is a view showing still another embodiment of a reaction trap.
6 is a diagram showing a basic embodiment of the evacuation system of the present invention.
7 is a diagram showing still another embodiment of the vacuum exhaust system.
FIG. 8 is a diagram showing an overall configuration of a conventional evacuation system.
[Explanation of symbols]
10 Process (vacuum) chamber 12 Vacuum pump 14 Exhaust piping
16 reaction trap 26,6 2 sacrificial牲材charge 74 differential pressure sensor

Claims (8)

An exhaust pipe (14) communicating the process chamber (10) and a vacuum pump (12) for exhausting the chamber reacts with a predetermined active component of the exhaust gas from the process chamber and deactivates it. A sacrificial material (26, 62) is disposed, the sacrificial material has air permeability, and is accommodated in a reaction trap (16) disposed in the middle of the exhaust pipe, and between the sacrificial material and the vacuum pump, A vacuum exhaust system comprising a low temperature trap (70, 72) for condensing and removing a product resulting from a reaction between a predetermined active ingredient and a sacrificial material from exhaust gas at a low temperature. The vacuum exhaust system according to claim 1, wherein the vacuum pump is a dry pump that does not use lubricating oil in an exhaust path. The vacuum exhaust system according to claim 1 or 2, wherein the reaction trap is detachably attached to the exhaust pipe. 3. The vacuum exhaust system according to claim 1, wherein the reaction trap is connected to the exhaust pipe so as to be selectively conductive in parallel with two systems. 4. The evacuation system according to claim 1, wherein the reaction trap is provided with a sensor that indicates a remaining amount of the sacrificial material. The vacuum exhaust system according to claim 1 or 2, wherein a sensor (74) for detecting a differential pressure before and after the reaction trap is provided. The evacuation system according to claim 1, wherein the sacrificial material includes at least one of a group consisting of C, Si, and S. The evacuation system according to claim 1, wherein the sacrificial material is a metal.

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