JPH05109654A - Film formation treatment system - Google Patents

Abstract

PURPOSE:To prevent a reaction product from adhering to a gas flowing part by cooling down the part at the temperature not exceeding specific value. CONSTITUTION:Within the title film formation processor of a metallic film having a treated body holding means 6 holding the treated body 4 and a gas feeding nozzle 12, a cooling means 36 is fitted to the rectifier cylinder 30 of a gas flow controller 26 so that a relatively intensive refrigerant such as ethylene glycol 46, etc., may be fed to cool down the rectifier cylinder 30 at the temperature not exceeding -5 deg.C. Through these cooling down procedures, the rectifier cylinder 30 can be cooled down at the temperature not exceeding the reaction temperature of a reactive gas thereby enabling the adherence of a reactive product to be restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming apparatus.

[0002]

2. Description of the Related Art Generally, as a film forming technique for depositing a thin film of an electrode material or a conductive material on the surface of a semiconductor wafer, one or more compound gas (reactive gas) consisting of elements forming the thin film is applied to the wafer surface. And a chemical reaction on the surface of the wafer to form a desired thin film.
VD) is known. Examples of the film forming apparatus include a batch type apparatus for forming a large number of wafers in a vertical or horizontal direction at narrow intervals to form an insulating thin film such as SiO _2, and a batch type apparatus. A single-wafer type apparatus mainly used for forming a metal film is known because a uniform film formation cannot be obtained.

In the above-mentioned single-wafer type film forming apparatus, for example, a wafer is carried into a container in a vacuum atmosphere and heated and held at a predetermined temperature (about 360.degree. C. to 700.degree. C.). Tungsten hexafluoride (WF ₆ ) and a reactive gas such as silane (SiH ₄ ) or dichlorosilane (SiH ₂ CL ₂ ) are mixed at a predetermined ratio from a portion facing to, and supplied to the wafer surface in the vacuum container. A desired thin film, for example, WSix is formed by a chemical reaction on the wafer surface. In this case, a plurality of wafers (for example, 25 wafers) housed in each cassette are set as one unit and the wafers are continuously subjected to thin film processing.

[0004]

By the way, in the conventional apparatus of this type, the radiant heat from the heating source of the holding portion of the wafer is transferred to the flow section of the reactive gas. Are heated to a temperature higher than the reaction initiation temperature of tungsten hexafluoride, that is, about 50 to 100 ° C., and as a result, products of reactive gas (WSix) and the like adhere to the surface of the member forming the gas flow portion. There was a case to do. Further, this product has a catalytic action, so that the reaction is promoted, a chemical reaction occurs even at a temperature lower than the above temperature, and at the same temperature, film formation proceeds at a high rate, As a result, there is an improvement in that the reactive gas is non-uniformly supplied to the wafer and the in-plane and inter-plane film thickness of each wafer is non-uniform.

Further, the film adhered to the gas flow portion may be peeled off by heat to become fine particles, that is, particles, and adhere to the object to be processed, which not only lowers the product yield but also increases the reliability of the film forming process. There was also an improvement point that it lacked. The present invention has been made to pay attention to the above problems and to solve them effectively. An object of the present invention is to provide a film forming apparatus capable of preventing a reaction product from adhering to this portion by cooling the gas circulation portion.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an object holding means for holding an object to be processed in a vacuum container while heating it to a predetermined temperature, and the vacuum container. A gas supply nozzle for supplying a reactive gas therein, and a film forming apparatus for forming a metal film on a surface of the object to be processed, wherein the object holding means and the gas supply nozzle are A gas flow control unit for controlling the flow of the reactive gas is provided, and the gas flow control unit is provided with a cooling means for cooling the gas flow control unit to a temperature not higher than the reaction temperature of the reactive gas. is there.

[0007]

Since the present invention is configured as described above, the reactive gas supplied from the gas supply nozzle rises in the vacuum container and is reactively generated on the surface of the object to be processed held by the object holding means. An object metal film is deposited. Further, the gas flow control unit that controls the flow of the reactive gas tends to be heated by the radiant heat from the heating source that heats the object to be processed. It is cooled below the reaction temperature of the gas. Therefore, it is possible to prevent the metal film from adhering to the surface of the gas flow control unit due to the products of the reactive gas, so that the reactive gas is supplied to the object to be processed at an appropriate concentration and mixing ratio. Therefore, it is possible to perform a film forming process with a uniform film thickness.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the film forming apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic sectional view showing a film forming processing apparatus according to the present invention, and FIG. 2 is a schematic sectional perspective view showing a gas flow control unit of the apparatus shown in FIG. As shown in the figure, in this embodiment, a case where a metal film of WSix is formed on the surface of a semiconductor wafer by a film forming apparatus under a low pressure will be described. This film formation processing apparatus 2 is
A cylindrical vacuum container 8 in which a chuck plate 6 made of graphite, which is an object-to-be-processed holding means for holding a semiconductor wafer 4 as an object to be processed by fingers (not shown), is arranged in a ceiling portion, and the vacuum container 8 And a reaction gas mixing container 10 communicating with the lower part of the container. Each of these containers is made of, for example, aluminum.

An annular gas supply nozzle 12 for supplying a reactive gas such as WF ₆ or SiH ₄ is arranged in the mixing container 10, and a concentric circle is provided on the ceiling of the vacuum container 8. Exhaust ports 14 are provided at four locations. These exhaust ports 14 are connected to a suction means (not shown) so that the vacuum container 8 and the mixing container 10 are maintained in a vacuum atmosphere. The wafer 4 is attached to the side wall of the vacuum container 8.
There is a window 16 for loading and unloading
A gate valve 18 that holds the vacuum container 8 and the mixing container 10 in a vacuum atmosphere when the valve is closed is openably and closably attached. In addition, a load lock chamber (not shown) for keeping the inside of the containers 8 and 10 in a vacuum state at the time of loading and unloading the wafer is connected to the window 16 via a gate valve 18. Further, on the back side, that is, on the upper side of the chuck plate 6, a quartz glass 20 that shuts off the atmosphere and the vacuum vessel 8 is attached via an O-ring 22, and a heating lamp 24 is placed on the quartz glass 20. Is arranged so that the chuck plate 6 is heated to about 360 to 700 ° C. It is also possible to embed a heating heater in the chuck plate 6 instead of the heating lamp 24. The space between the quartz glass 20 and the chuck plate 6 is in a vacuum state.

On the other hand, a gas flow control section 26 for controlling the flow of the reactive gas is formed in the gas flow section between the vacuum container 8 and the mixing container 10. The gas flow control unit 26 is
Inside the rectifying cylinder 30, an annular rectifying cylinder 30 standing upright on the communication port 28, a projecting wall 32 protruding from the lower side of the rectifying cylinder 30 toward the inner side of the rectifying cylinder 30, and the inside of the rectifying cylinder 30. The protrusion wall 32 is disposed so as to be movable in the vertical direction with a gap L1.
And a rectifying body 34 that controls the flow of the reactive gas by varying the gap L2 between In this case, the straightening cylinder 3
0 and the rectifying body 34 are formed of a material having good thermal conductivity, for example, an aluminum alloy.

An annular refrigerant supply chamber 36 as a cooling means, which is a feature of the present invention, is formed in the rectifying cylinder 30 at a position close to the upper end surface and the inner side surface. Is connected to a flexible coolant supply pipe 38 made of, for example, a bellows-shaped stainless pipe, and the end of the supply pipe 38 is provided so as to penetrate the vacuum container wall. This supply pipe 38 is provided with an on-off valve 40 on the way.
A coolant supply source such as a pump 44 and a coolant storage tank 46 are connected to the coolant passage 42 through the. In the present embodiment, since the rectifying cylinder 30 is cooled to −5 ° C. or lower, ethylene glycol is used as the refrigerant. In addition, a refrigerant discharge pipe 39 is connected to the refrigerant supply chamber 36 in parallel with the refrigerant supply pipe 38 so that ethylene glycol, which is a refrigerant, can be circulated and used. Further, a water cooling chamber 50 is formed on the head of the rectifying body 34 so as to be close to the upper end surface and the outer side surface of the rectifying body head. This water cooling room 50
Is connected via a cooling water supply pipe 52 and an on-off valve 54 to a pump 56, which is a cooling water supply source, and a cooling water storage tank 58. A drain pipe 60 is connected to the water cooling chamber 50 so that cooling water is circulated and supplied.
The plunger portion 36a of the rectifying body 34 and the mixing container 1
An O-ring 62 is interposed between 0 and 0 to maintain airtightness.

Further, the gas supply nozzle 12 has a plurality of injection ports (not shown) at the upper surface 45 ° positions of the two annular chambers 64a and 64b provided concentrically on the annular base body 64 made of, for example, stainless steel. It has a structure in which holes are provided at appropriate intervals, and an annular water cooling chamber 68 is formed between both annular chambers 64a and 64b. This water cooling room 68
The pump 56 and the cooling water storage tank 58 are connected to the cooling water supply pipe 70 connected to the
The cooling water in the tank 58 is circulated and supplied from the cooling water supply pipe 70 into the water cooling chamber 68 by driving the pump 56, and it is possible to prevent the gas supply nozzle 12 from being excessively heated by the radiant heat from the heating lamp 24. It is like this.
In addition, in the annular chambers 64a and 64b, the conduits 74 and 7 are respectively provided.
6 is connected, and a WF ₆ gas cylinder or a SiH ₄ gas cylinder (not shown) is connected to the pipes 74 and 76, respectively, and WF ₆ gas and SiH ₄ gas are supplied into the mixing chamber 4 at a predetermined ratio. After being mixed in the mixing container 10, it is supplied into the vacuum container 8. still,
Each of the vacuum container 8 and the mixing container 10 is formed of a material having good corrosion resistance and heat conductivity, such as an aluminum alloy, and an annular water cooling chamber 80 is formed at an arbitrary position of the vacuum container 8 and the vacuum container during thin film processing. 8 and the mixing container 10 are prevented from reaching a high temperature.

Next, the operation of this embodiment configured as described above will be described. First, after vacuuming the inside of the vacuum container 8 and the mixing container 10 and confirming the vacuum atmosphere, WF ₆ gas and SiH ₄ gas are supplied into the vacuum container 8 (hereinafter referred to as an empty depot), and the chuck plate A film of the product produced by the thin film treatment is attached to the surface of 6.
Then, the start switch is turned on, and WF ₆ gas and SiH are put into the vacuum container 8 in a state where the wafer 4 is not loaded.
₄ Empty the gas. Due to this pre-treatment empty deposition, the inside of the vacuum container 8 is brought into a state equivalent to the thin film processing atmosphere. In this state, the wafer 4 is loaded into the vacuum container 8 from the load lock chamber through the window 16, and the wafer 4 is held by the chuck plate 6 and heated to a predetermined temperature by heating from the heating lamp 24. ..

In this state, the WF ₆ gas and the SiH ₄ gas are supplied into the mixing container 10 and mixed, and then flown into the vacuum container 8 through the gas flow controller 26. A reaction occurs, and a desired thin film, that is, a metal film of WSix is formed on the wafer surface by this chemical reaction. At this time, as a reaction condition, the chuck plate 6 made of graphite is heated to about 360 ° C. to maintain the wafer temperature at about 310 ° C.
The pressure inside is maintained at about 200 mTorr. Also, Si
The flow rate of H ₄ is set to about 300 SCCM and WF
Set the flow rate of ₆ to 2 SCCM and set it for a predetermined time, for example about 2
A film forming process is performed for 50 seconds. During film formation, when the reactive gas mixed in the mixing container 10 flows into the vacuum container 8 and contacts the wafer 4, this gas flow is generated by the gas flow control unit 26.
Since it is guided by the straightening cylinder body 30 and rises, it uniformly contacts the wafer 4. Then, during this film forming process, the cooling water in the cooling water storage tank 58 is cooled by the cooling water supply pipe 5.
Rectifier 34 and gas supply nozzle 12 via 2, 70, etc.
And the like are circulated in water cooling chambers 50, 68, 80 to cool them to a predetermined temperature, for example, a temperature in the range of 15 to 20 ° C., to prevent reaction products from adhering to these members. ..

At the same time, the distance between the chuck plate 6 and the chuck plate 6 is as small as 30 to 40 mm, and the coolant supply chamber 36 of the rectifying cylinder 30 of the gas flow control unit 26, which tends to be heated most, contains cooling water. Instead of separately supplying the ethylene glycol, which is a stronger refrigerant than the cooling water, from the separately-provided refrigerant storage tank 46 through the refrigerant supply pipe 38, the rectifying cylinder 30 is -5 ° C or less, preferably as described later- 20 ° C
Cool to: Therefore, even if the reactive gas comes into contact with this portion, the reaction initiation temperature of these gases, for example, 50 ° C.
Since the rectifying cylinder 30 is cooled to a lower temperature, the reaction is locally suppressed, and the reaction product of SiH ₄ and WF ₆ is prevented from adhering to the rectifying cylinder 30. In this case, if ethylene glycol is caused to flow not only in the rectifying cylinder 30 but also in the rectifying body 34 and cooled to a low temperature of about -20 ° C, the adhesion of reaction products as a whole is further suppressed.

Further, since the adhesion of the reaction product is suppressed, the generation of particles accompanying the peeling of the adhered product is also suppressed. Table 1 below shows the number of particles, in-plane and inter-plane uniformity obtained as a result of film-forming processing of 50 wafers by appropriately changing the cooling temperature of the rectifying cylinder 30 under the above reaction conditions. ..

[0017]

[Table 1]

As is clear from Table 1, the straightening cylinder 3
It is found that the in-plane uniformity of the number of particles, the film thickness, and the in-plane uniformity are improved as the temperature of 0 is sequentially decreased from + 20 ° C to -20 ° C. Especially, the cooling temperature is -5 ℃
When set to, the number of particles is significantly reduced, and the standard number of particles is 5 at a cooling temperature of -20 ° C.
The number of particles is 10 which is far below 0, showing the best result. As described above, in the present embodiment, the rectifying cylinder 30 of the gas flow control unit 26 is cooled to the reaction temperature of the reaction gas or less, so that the reaction product does not adhere to this portion, and therefore the reaction Generation of particles due to peeling of the product can also be suppressed.

Further, since the outer walls of the vacuum container 8 and the mixing container 10 are cooled by ordinary cooling water to prevent excessive cooling, dew condensation does not occur on the outer walls and the like. Condensation does not drip on an electronic device or the like (not shown) located in the position, and a problem such as a short circuit of the electronic device does not occur. Further, in the above embodiment, ethylene glycol was used as the cooling medium for cooling the rectifying cylinder 30, but the invention is not limited to this, and other cooling medium may be used. Further, in the above embodiment, the refrigerant supply chamber 36
In order to enhance this cooling effect, it is preferable to form an annular shape at a portion close to the upper end surface and the inner side surface of the rectifying cylinder 30, and when forming a refrigerant supply chamber in the rectifying body 34, It is preferable to provide this at a portion close to the upper end surface and the outer side surface of 34.

Further, in the above embodiment, the case where the projecting wall 32 is provided at the lower portion of the flow straightening cylinder 30 has been described, but the present invention is not limited to this, and the projecting wall is projected on the inner peripheral surface of the flow straightening cylinder 30, for example. Alternatively, a projecting wall may be provided on the outer peripheral surface of the rectifying body 34. Furthermore, in the present embodiment, the rectifying cylinder 30 is shaped to have a rectangular cross section, but is not limited to this.
For example, as shown in FIG. 3, the rectifying cylinder 30 may be tapered to have a triangular cross section so that its lateral width is gradually reduced upward. In this case, by setting the cross-sectional shape of the refrigerant supply chamber 36 to have a triangular shape corresponding to the cross-sectional shape of the flow straightening cylinder 30, a chuck serving as a heating source located above the flow straightening cylinder 30 is configured. Plate 6
Even though the projected area of the straightening cylinder is the same, the distance of the tapered surface of the cylinder to the plate becomes longer, so the heating temperature of this portion becomes lower than that in the previous embodiment, and as a result, the cooling efficiency of the straightening cylinder 30 is improved. Can be increased.

Further, although the case where SiH ₄ and WF ₆ are used as the reactive gas has been described in the above embodiment, the present invention is not limited to this, and the case where a metal film is deposited using another reactive gas. Needless to say, the present invention can also be applied to such a case, and in that case, the cooling temperature of the flow straightening cylinder is appropriately selected according to the reactive gas.

[0022]

As described above, according to the present invention, the following excellent operational effects can be exhibited. Since it is possible to prevent the gas flow control unit from being heated above the reaction temperature of the reactive gas, it is possible to prevent the metal film as a reaction product from adhering to this portion. Therefore, it is possible to suppress the generation of particles due to peeling of the reaction product, and it is possible to improve the yield of products. Further, for the reason described above, it is possible to prevent the reactive gas from being consumed while rising, so that the reactive gas can be uniformly supplied within the surface of the object to be processed, and the surface of the film formation can be reduced. And the in-plane uniformity can be improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a film forming processing apparatus according to the present invention.

FIG. 2 shows a gas flow controller of the film forming process shown in FIG.

FIG. 3 is a sectional view showing a gas flow controller according to another embodiment of the present invention.

[Explanation of symbols]

 2 Film Forming Processing Device 4 Semiconductor Wafer (Processing Object) 6 Chuck Plate (Processing Object Holding Means) 8 Vacuum Container 10 Mixing Container 12 Gas Supply Nozzle 24 Heating Lamp 26 Gas Flow Control Section 30 Rectifying Cylindrical Body 34 Rectifying Body 36 Refrigerant supply chamber (cooling means) 46 Refrigerant storage tank 50, 68, 80 Water storage chamber 58 Cooling water storage tank

Claims (2)

[Claims] 1. An object-to-be-processed holding means for holding an object to be processed in a vacuum container in a state of being heated to a predetermined temperature, and a gas supply nozzle for supplying a reactive gas into the vacuum container, In a film forming apparatus for forming a metal film on a surface of an object to be processed, a gas flow control unit for controlling a flow of the reactive gas is provided between the object-to-be-processed holding means and the gas supply nozzle. A film forming apparatus characterized in that the flow control unit is provided with a cooling means for cooling the gas flow control unit to a temperature not higher than the reaction temperature of the reactive gas. 2. The cooling means is configured to cool the gas flow control unit to −5 ° C. or lower when a metal film of WSix is formed using SiH ₄ and WF ₆ as the reactive gas. The film forming apparatus according to claim 1, wherein