JP3563565B2 - Exhaust device and exhaust method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust device used for a film forming apparatus for forming a thin film such as a Ti film, and more particularly to an exhaust device and an exhaust method in which maintenance of a trap used in an exhaust system is considered in a cleaning process.
[0002]
[Prior art]
In a semiconductor device, a buried layer for electrical connection between layers such as a metal wiring layer, a contact hole which is a connection portion between a lower device and an upper wiring layer, and a via hole which is a connection portion between upper and lower wiring layers. Further, a metal-based thin film such as a barrier layer having a two-layer structure of a Ti (titanium) film and a TiN (titanium nitride) film, which is formed to prevent diffusion before forming the buried layer, is used.
[0003]
Such metal-based thin films have been formed using physical vapor deposition (PVD). However, recently, miniaturization and high integration of devices have been particularly required, and design rules have become particularly strict. As the line width and the opening diameter of the hole are further reduced and the aspect ratio is increased, it is particularly difficult to form the PVD film at the bottom of the hole in the Ti film and the TiN film constituting the barrier layer. It has become.
[0004]
Therefore, a Ti film and a TiN film constituting a barrier layer are formed by chemical vapor deposition (CVD), which can be expected to form a higher quality film. When a Ti film is formed by CVD, TiCl ₄ (titanium tetrachloride) and H ₂ (hydrogen) are used as reaction gases. When a TiN film is formed, TiCl ₄ is used as a reaction gas. NH ₃ (ammonia) or MMH (monomethylhydrazine) is used.
[0005]
By the way, when the above-mentioned thin film is formed by CVD, the film is deposited on a semiconductor wafer which is a substrate on which a film is to be formed, and the deposit also adheres to a chamber wall. For this reason, after the film formation is completed, the inside of the chamber is cleaned prior to the next film formation. In the cleaning at this time, a method has recently been adopted in which a chamber wall and a susceptor are heated, and a deposit is decomposed by introducing ClF ₃ gas into the chamber.
[0006]
At the time of cleaning after forming the Ti film, ClF ₃ gas and Ti react with each other to generate TiF ₄ as a reaction product. Therefore, the exhaust system is provided with a trap for trapping the TiF ₄ . In the maintenance of such a trap, the exhaust system is conventionally stopped, the exhaust system is brought to atmospheric pressure, and then the trap is removed.
[0007]
[Problems to be solved by the invention]
However, since the exhaust system is stopped during maintenance of the trap, the film forming apparatus must be stopped, which is inefficient. On the other hand, a double trap system in which exhaust is performed in one of two exhaust paths provided with a trap is disclosed (for example, Japanese Patent Laid-Open No. 8-176829). In addition, when the trap is removed during maintenance, the inside of the trap becomes atmospheric pressure, and the reaction products in the trap may cause a chemical reaction.
[0008]
The present invention has been made in view of such circumstances, there is no need to stop the device at the time of maintenance of the trap used for cleaning, without increasing the size of the device, and when removing the trap It is an object of the present invention to provide an exhaust device and an exhaust method in which a reaction product therein does not cause a chemical reaction.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, a first aspect of the present invention provides a film formation method in which a substrate to be processed is installed in a chamber, a film formation process is performed on the substrate to be processed, and then a cleaning gas is introduced into the chamber to perform a cleaning process. An exhaust device used for the device,
A main exhaust line connected to the chamber,
An exhaust pump provided in the main exhaust line,
A bypass line that bypasses the main exhaust line;
A trap detachably provided on the bypass line,
A vacuum sealing valve for vacuum sealing the inside of the trap,
Gas supply means for filling gas in the former part and the latter part of the trap of the bypass line,
A first on-off valve for opening and closing the main exhaust line;
A second opening / closing valve for opening / closing the bypass line.
[0010]
A second invention provides the exhaust device according to the first invention, further comprising a heating device for heating a portion of the bypass line up to the trap.
[0011]
A third invention is an exhaust method for performing exhaust using the exhaust device of the first invention. In the film forming process, the first opening / closing valve is opened to exhaust air through the main exhaust line. During the cleaning process, the second open / close valve is opened to exhaust air through the bypass line,
When the trap is removed, the inside of the trap is depressurized, the vacuum sealing valve is closed and the chamber is vacuum-sealed, and the gas is supplied to the front and rear parts of the bypass line by the gas supply means to reach atmospheric pressure. And an evacuation method which is performed after the evacuation.
[0012]
A fourth aspect of the present invention provides the film forming method according to the third aspect, wherein the trap is maintained while performing the film forming process while exhausting the gas through the main exhaust line.
[0013]
In the present invention, the exhaust system is divided into a main exhaust line and a bypass line, a trap is provided in the bypass line, and the main exhaust line and the bypass line can be opened and closed by a valve. The exhaust was performed through the main exhaust line, and during the cleaning process, a trap was provided and the exhaust was performed through a bypass line that bypassed the main exhaust line. When the trap was removed, the pressure inside the trap was reduced. It can be carried out after vacuum sealing and gas filling at the front and rear portions of the trap of the bypass line to make it atmospheric pressure. Therefore, the film can be formed using the main exhaust line during the maintenance of the trap, and there is no possibility that a chemical reaction occurs in the reaction product in the trap.
[0014]
Further, as in the second invention, by heating the portion of the bypass line up to the trap with the heating device, it is possible to prevent the reaction product generated during cleaning from adhering to the bypass line.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a sectional view showing a CVD-Ti film forming apparatus according to one embodiment of the present invention. This film forming apparatus has a substantially cylindrical chamber 1 which is airtightly arranged, and in which a susceptor 2 for horizontally supporting a semiconductor wafer W to be processed is a cylindrical supporting member. 3 and is supported. A guide ring 4 for guiding the semiconductor wafer W is provided at an outer edge of the susceptor 2. Further, a heater 5 is embedded in the susceptor 2, and the heater 5 is heated by a power source 6 to heat the semiconductor wafer W, which is an object to be processed, to a predetermined temperature. A controller 7 is connected to the power supply 6, whereby the output of the heater 5 is controlled in accordance with a signal from a temperature sensor (not shown).
[0016]
On the top wall 1a of the chamber 1, a shower head 10 is provided so as to face the semiconductor wafer W supported by the susceptor 2, and a large number of gas discharge holes 10a are formed on the lower surface facing the wafer W. ing. A space 11 is formed inside the shower head 10, and a dispersion plate 12 having a large number of holes formed therein is provided therein. A gas inlet 13 for introducing gas into the space 11 inside the shower head 10 is formed at the center of the top wall 1 a of the chamber 1, and a gas supply pipe 15 is connected to the gas inlet 13.
[0017]
An H ₂ source 16, an Ar source 17, a TiCl ₄ source 18, and a ClF ₃ source 19 are connected to the gas supply pipe 15 via a pipe 15a, and a desired gas is supplied from the gas source to the gas supply pipe 15 and the shower. It is supplied into the chamber 1 through the head 10. At the time of film formation, an H ₂ gas, an Ar gas, and a TiCl ₄ gas are supplied from an H ₂ source 16, an Ar source 17, and a TiCl ₄ source 18, respectively, and thereby a Ti film is formed on the semiconductor wafer W. Further, when cleaning the inside of the chamber 1, the ClF ₃ gas is supplied from the ClF ₃ source 19. Note that a pipe 26a from each gas source is provided with a valve 26 and a mass flow controller 27.
[0018]
A high frequency power supply 23 is connected to the top wall 1a of the chamber 1 via a matching circuit 22, and high frequency power can be applied from the high frequency power supply 23 to the top wall 1a. With this high frequency power, a plasma of a film forming gas is formed in the chamber 1. The space between the top wall 1a of the chamber 1 and the side wall of the chamber 1 is electrically insulated by the insulating member 14, and the chamber 1 is grounded.
[0019]
An exhaust port 8 is provided on the bottom wall 1 b of the chamber 1, and an exhaust system 9 for exhausting the inside of the chamber 1 is connected to the exhaust port 8.
As shown in FIG. 2, the exhaust system 9 includes a main exhaust line 31, and the main exhaust line 31 is connected to the exhaust port 8 of the chamber 1. The main exhaust line 31 is provided with a vacuum pump 33 for exhaust.
[0020]
A bypass line 32 is provided in the vicinity of the exhaust port 8 of the main exhaust line 31 (branch point A), and the bypass line 32 is provided before the vacuum pump 33 of the main exhaust line 31 (joining point B). It is connected to the. The bypass line 32 is provided with a trap 34 for capturing a reaction product. Valves 37 and 38 are provided on the upstream side and the downstream side of the trap 34. After the inside of the trap 34 is evacuated, the inside of the trap 34 can be vacuum-sealed by closing the valves 37 and 38. It has become. Removal parts C and D exist outside the valves 37 and 38, and the trap 34 can be removed at the removal parts C and D.
[0021]
A valve 35 and a valve 36 are provided downstream of the branch point A of the main exhaust line 31 and the bypass line 32, respectively. The valves open and close the main exhaust line 31 and the bypass line 32, respectively. . Further, an opening / closing valve 39 is provided further downstream of the removal portion D on the downstream side of the bypass line 32.
[0022]
On the other hand, a gas supply line 40 is connected between the valve 36 and the valve 37 and between the valve 38 and the valve 39 of the bypass line 32. This gas supply line 40 is connected to N ₂ gas cylinder 41, between the valve 36 and the valve 37 of the bypass line 32, and to be able to supply N ₂ gas into the portion between the valve 38 and the valve 39 It has become. The gas supply line 40 is provided with a valve 42 for supplying and stopping the N ₂ gas. As the gas used in this, it is possible to use other inert gases Ar gas or the like is not limited to N _2.
In addition, it is preferable to install a sensor for pressure monitoring between each valve for safety.
[0023]
In the apparatus configured as described above, first, the semiconductor wafer W is charged into the chamber 1 and the valve 35 of the exhaust system 9 is opened while heating the wafer W to a temperature of, for example, 450 to 600 ° C. by the heater 5. With the valves 38 and 40 closed and the exhaust path on the side of the main exhaust line 31, the vacuum pump 33 is evacuated to a high vacuum state, the inside of the chamber 1 is set to, for example, 0.1 to 1 Torr, , H ₂ gas and TiCl ₄ are pre-flowed at a predetermined flow rate for about 5 to 20 seconds, and then the gas is flowed under the same conditions to form a Ti film for a predetermined time. After the film formation, the semiconductor wafer W is carried out of the chamber 1.
[0024]
Since Ti is deposited on the chamber 1 and the susceptor 2 after the film formation, the inside of the chamber 1 is cleaned. In this cleaning, the supply of the TiCl ₄ gas and the H ₂ gas for film formation is stopped, and the ClF ₃ gas is supplied into the chamber 1. At this time, the susceptor 2 and the chamber wall are heated to, for example, about 300 ° C. by the heater 5 of the susceptor 2 and a heater (not shown) provided on the chamber wall. Since ClF ₃ has high reactivity, it is possible to generate titanium tetrafluoride (TiF ₄ ) that reacts with Ti and gasifies at a predetermined temperature or more by merely heating in such a manner, and discharges it to the outside of the chamber. That is, plasma rescreening is possible by using ClF ₃ as a cleaning gas, and cleaning can be performed extremely easily.
[0025]
In this case, the exhaust is performed through the bypass line 32 by the vacuum pump 33 in a state where the valve 36 is opened, the valve 35 is closed, and the exhaust path is on the bypass line 32 side. TiF _{4 in} the exhaust gas led to the bypass line 32 is captured by the trap 35.
[0026]
When maintenance of the trap 34 is performed, the vacuum pump 33 is operated with the valves 35, 36, and 37 closed and the valves 38 and 39 open, and the inside of the trap 34 is evacuated to a reduced pressure state. The valves 38 and 39 are closed to vacuum-enclose the trap 34. Then, the valve 42 is opened to supply N ₂ gas from the N ₂ gas cylinder 41 to the portion between the valve 36 and the valve 37 and the portion between the valve 38 and the valve 39 of the bypass line 32, and these portions are set to the atmospheric pressure. Then, the trap 34 is removed from the removal parts C and D.
On the other hand, by opening the valve 35 when the valves 38 and 39 are closed as described above, the exhaust operation by the main exhaust line 31 becomes possible, and the film forming process can be performed.
[0027]
Therefore, the film forming process can be performed simultaneously with the maintenance of the trap 34, and the film forming process can be continued even when the trap 34 is removed. As described above, the film formation process can be performed even during the maintenance of the trap, so that the efficiency is extremely high.
[0028]
Further, since the trap 34 removed as described above is sealed in a vacuum, there is no possibility that a chemical reaction occurs in a reaction product therein. The trap 34 in this state is transported to the maintenance place, where it is purged with N ₂ and washed.
[0029]
When exhausting the cleaning gas, there is a possibility that TiF _{4 as} a reaction product may adhere to the exhaust line. Therefore, as shown in FIG. A heating device 43 is provided at a portion reaching the branch point A of the line, and these portions are heated to a temperature equal to or higher than the gasification temperature of TiF ₄ . This avoids the adverse effects of TiF ₄ adhesion.
[0030]
Note that the present invention can be variously modified without being limited to the above embodiment. For example, in the above-described embodiment, an example in which a Ti film is formed by CVD and cleaning is performed using a ClF ₃ gas has been described. However, the present invention is not limited to this. However, it is effective in producing a reaction product adhered to the exhaust system during cleaning.
[0031]
In the above embodiment, the case where a semiconductor wafer is used as a substrate to be processed has been described. However, the present invention is not limited to this, and another substrate such as an LCD substrate may be used. Alternatively, another substrate may be formed on the substrate. It may be.
[0032]
【The invention's effect】
As described above, according to the present invention, the exhaust system is divided into a main exhaust line and a bypass line, a trap is provided in the bypass line, and the main exhaust line and the bypass line can be opened and closed by a valve. During processing, exhaust is performed through the main exhaust line of the exhaust system, during cleaning, exhaust is performed through a bypass line that is provided with a trap and bypasses the main exhaust line, and when removing the trap, After the pressure in the trap is reduced, the air is vacuum-sealed, and the gas is sealed in the front and rear parts of the bypass line trap to bring the pressure to atmospheric pressure. Therefore, the film can be formed using the main exhaust line at the time of maintenance of the trap, and the efficiency can be increased without increasing the size of the device as in the case of a double trap. The possibility that a reaction occurs can be avoided.
[0033]
Further, according to the second aspect, the portion of the bypass line up to the trap is heated by the heating device, so that reaction products generated during cleaning can be prevented from adhering to the bypass line.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a film forming apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing an exhaust system of the film forming apparatus of FIG.
FIG. 3 is a diagram showing another example of the exhaust system.
[Explanation of symbols]
1 ...... chamber 2 ...... susceptor 8 ...... exhaust port 9 ...... exhaust system 10 ...... showerhead 10a ...... gas discharge holes 16 ...... _{H 2} source 17 ...... Ar source 18 ...... TiCl ₄ source 19 ...... ClF ₃ source 31 ...... main exhaust line 32 ...... bypass line 33 ...... vacuum pump 34 ...... trap 35,36,37,38,39,42 ...... valve 40 ...... gas supply line 41 ...... _{N 2} gas cylinder 43 ... ... Heating device W ... Semiconductor wafer

Claims (4)

An exhaust device used for a film forming apparatus that installs a substrate to be processed in a chamber, performs a film forming process on the substrate to be processed, and then performs a cleaning process by introducing a cleaning gas into the chamber,
A main exhaust line connected to the chamber,
An exhaust pump provided in the main exhaust line,
A bypass line that bypasses the main exhaust line;
A trap detachably provided on the bypass line,
A vacuum sealing valve for vacuum sealing the inside of the trap,
Gas supply means for filling gas in the former part and the latter part of the trap of the bypass line,
A first on-off valve for opening and closing the main exhaust line;
A second opening / closing valve for opening and closing the bypass line. The exhaust device according to claim 1, further comprising a heating device configured to heat a portion of the bypass line up to the trap. An exhaust method for exhausting by using the exhaust device according to claim 1, wherein in the film forming process, the first opening / closing valve is opened and the exhaust is performed through the main exhaust line to perform the exhaust process. Open the second on-off valve and exhaust through the bypass line,
When the trap is removed, the inside of the trap is depressurized, the vacuum sealing valve is closed and the chamber is vacuum-sealed, and the gas is supplied to the front and rear parts of the bypass line by the gas supply means to reach atmospheric pressure. Exhaust method, which is performed after the exhaust. 4. The exhaust method according to claim 3, wherein the trap is removed at the same time as performing the film forming process while exhausting the gas through the main exhaust line.

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