JP3835376B2 - Deposition processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a film forming apparatus for forming a metal thin film, for example.
[0002]
[Prior art]
In general, in the manufacturing process of a semiconductor integrated circuit, W (tungsten), WSi (tungsten silicide), Ti (in order to form a wiring pattern on the surface of a semiconductor wafer, which is an object to be processed, or to fill a recess such as between wirings. Thin films are formed by depositing metals or metal compounds such as titanium), TiN (titanium nitride), and TiSi (titanium silicide).
[0003]
The method for forming the metal thin film of this kind, three methods, for example, H ₂ (hydrogen) reduction method, SiH ₄ (silane) reduction method, SiH ₂ Cl ₂ (dichlorosilane) and reduction methods are known, SiH ₂ Cl ₂ reduction method is a method of forming a W or WSi (tungsten silicide) layer at a high temperature of about 600 ° C. using dichlorosilane as for example reducing gas to form a wiring pattern, SiH ₄ reduction method, like In order to form a wiring pattern, for example, silane is used as a reducing gas, and a W or WSi film is formed at a low temperature of 370 to 400 ° C., which is lower than before.
[0004]
The H ₂ reduction method is a method of depositing a W film at a temperature of about 400 to 430 ° C. using, for example, hydrogen as a reducing gas in order to fill a hole on the wafer surface such as a recess between wirings.
In any of the above cases, for example, WF ₆ (tungsten hexafluoride) is used.
A typical film forming apparatus for forming such a metal thin film is shown in FIG. 3. In the processing chamber 2 formed into a cylindrical shape with aluminum or the like, for example, a thin carbon material or an aluminum compound is used. A molded mounting table 4 is provided, and below this, heating means 8 such as a halogen lamp is arranged through a transmission window 6 made of quartz.
[0005]
And the heat ray from the heating means 8 permeate | transmits the permeation | transmission window 6, reaches the mounting base 4, heats this, and heats and maintains the semiconductor wafer W arrange | positioned on it at predetermined temperature indirectly. At the same time, WF ₆ or SiH _4, for example, is uniformly supplied as a process gas from the shower head 10 provided above the mounting table 4 on the wafer surface, and a metal film such as W or WSi is formed on the wafer surface. Will be.
In this case, the metal film is deposited not only on the target wafer surface but also on a structure in the processing chamber, such as a processing chamber wall or shower head surface or a member near the wafer such as a clamp ring (not shown). When the deposit is peeled off, it becomes particles and causes a decrease in the yield of the wafer. Therefore, every time a predetermined number of wafers, for example, 25 wafers are processed, ClF ₃ is flowed as a cleaning gas to remove excessive deposited films such as W and WSi adhering to the surface of the internal structure.
[0006]
[Problems to be solved by the invention]
By the way, although a small amount of moisture enters the processing chamber as the wafer is loaded and unloaded, the moisture that has entered the processing chamber as the wafer is loaded and unloaded decomposes, and the generated oxygen forms tungsten and oxide. Therefore, this adheres to the lower surface of the shower head 10 which is exposed to a particularly high temperature.
[0007]
This tungsten oxide is a stable substance and cannot be completely removed by the ClF ₃ gas used for dry cleaning. Therefore, for example, every 1000 sheets, the entire apparatus must be disassembled and a wet cleaning process must be performed. The frequency of such a large-scale maintenance work has increased, which has caused a significant reduction in the apparatus operating rate.
[0008]
The present invention has been devised to pay attention to the above problems and to effectively solve them. An object of the present invention is to provide a film forming apparatus capable of reducing the frequency of wet cleaning work by forming a film forming prevention film on the surface of a shower head or the like.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a processing chamber having a mounting table on which an object to be processed is mounted, and a gas supply unit for supplying a processing gas into the processing chamber at a position facing the mounting table. in thin film deposition apparatus for forming a metal film or metal compound film on the surface of the object to be processed includes bets, the gas supply unit, a shower with a large number of gas holes you release the gas into the processing chamber Comprising a head, the shower head is formed of a metal having good thermal conductivity, and a film containing aluminum oxide is formed on the surface thereof, and means for maintaining the temperature of the shower head at a predetermined temperature is provided. A film forming apparatus comprising a means for discharging a cleaning gas made of a compound gas from the shower head into the processing chamber and cleaning the processing chamber .
[0010]
[Action]
Since the present invention is formed as described above, a metal film (including a metal compound film) deposited on the surface of the structure in the processing chamber, particularly on the surface opposite to the mounting table of the shower head that is a gas supply unit, is formed during the film forming process. Including the same, the same applies below).
Therefore, the frequency of maintenance work such as wet cleaning can be greatly reduced, and the operating rate of the apparatus can be improved.
In this case, a metal film is deposited by forming a structural material of the processing chamber, for example, a constituent material of the gas supply unit with a material having good thermal conductivity, and providing a cooling means for cooling the gas supply unit surface. Further suppression can be achieved.
[0011]
Further, oxides such as quartz, alumina, and alumite can be used as the film adhesion prevention film. In particular, the use of quartz can efficiently suppress the deposition of the metal film.
Furthermore, as a structure in the processing chamber, for example, a wall defining the processing chamber may be made of the above-mentioned material that is difficult to deposit, such as alumina.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a film forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a film forming apparatus according to the present invention, and FIG. 2 is an enlarged cross-sectional view showing a gas supply unit of the apparatus shown in FIG. Note that the same parts as those in the conventional apparatus shown in FIG.
[0013]
The deposition process equipment, for example aluminum or the like has a cylindrical or box shape to be molded a processing chamber 2 by, in the treatment chamber 2, on post 14 is erected from the processing chamber bottom For example, a mounting table 4 for mounting a semiconductor wafer W as an object to be processed is provided via a holding member 16 having an L-shaped cross section. The support column 14 and the holding member 16 are made of a heat ray transmissive material, for example, quartz, and the mounting table 4 is made of, for example, a carbon material or an aluminum compound having a thickness of about 1 mm.
Below the mounting table 4, a plurality of, for example, three lifter pins 18 are provided to stand upward with respect to the support member 20, and the support member 20 is provided so as to penetrate the bottom of the processing chamber. The wafer W can be lifted by being moved up and down by the push-up bar 22 so that the lifter pins 18 are inserted through the lifter pin holes 24 provided through the mounting table 4.
[0014]
The lower end of the push-up bar 22 is connected to an actuator 28 via a bellows 26 that can be expanded and contracted in order to maintain an internal airtight state in the processing chamber 2.
A ring-shaped ceramic clamp ring 30 for holding the peripheral portion of the wafer W and fixing it to the mounting table 4 side is provided on the peripheral portion of the mounting table 4 described above. The support member 20 is connected to the support member 20 through a support rod 32 that penetrates the holding member 16 in a loosely fitted state, and is moved up and down integrally with the lifter pin 18. Here, a coil spring 33 is interposed in the support bar 32 between the holding member 16 and the support member 20 to assist the lowering of the clamp ring 30 and the like and to securely clamp the wafer. The lifter pins 18, the support member 20, and the holding member 16 are also made of a heat ray transmitting member such as quartz.
[0015]
In addition, a transmission window 6 made of a heat ray transmission material such as quartz is airtightly provided at the bottom of the processing chamber directly below the mounting table 4, and a box-shaped heating chamber is provided below the transmission window 6 so as to surround the transmission window 6. 34 is provided. In the heating chamber 34, a plurality of, for example, four heating lamps 8 are attached as a heating means to a rotating table 36 that also serves as a reflecting mirror. The rotating table 36 is attached to the bottom of the heating chamber 34 via a rotating shaft 40. It is rotated by the provided rotary motor 38. Therefore, the heat rays emitted from the heating lamp 8 can pass through the transmission window 6 and irradiate the lower surface of the mounting table 4 to heat it.
The side wall of the heating chamber 34 is provided with a cooling air inlet 40 for introducing cooling air for cooling the room and the transmission window 6 and a cooling air outlet 42 for discharging the air.
[0016]
Further, on the outer peripheral side of the mounting table 4, a ring-shaped rectifying plate 46 having a large number of rectifying holes 44 is provided by being supported by a support column 48 that is annularly formed in the vertical direction. A ring-shaped quartz attachment 47 is provided on the inner peripheral side of the rectifying plate 46 so as to contact the outer peripheral portion of the clamp ring 30 and prevent gas from flowing below this. An exhaust port 50 is provided at the bottom of the rectifying plate 46, and an exhaust path 52 connected to a vacuum pump (not shown) is connected to the exhaust port 50, and a predetermined degree of vacuum (for example, within the processing chamber 2). 100 Torr to 10 ⁻⁶ Torr).
[0017]
Further, the partition wall 54 that partitions the processing chamber 2 is provided with a processing chamber cooling jacket 56 formed by sweeping the processing wall 2, and an inlet 58 for introducing cooling water and the cooling chamber 56 are provided in this jacket. Is provided to cool the inner wall of the processing chamber 2 to prevent deposits from adhering thereto.
[0018]
On the other hand, a gas supply unit 62 for introducing a necessary gas such as a processing gas or a cleaning gas into the processing chamber 2 is provided on the processing chamber ceiling facing the mounting table 4. Specifically, the gas supply unit (shower head) 62 has a shower head structure, and has a head main body 64 formed into a circular box shape with aluminum or the like, for example. 66 is provided.
The gas inlet 66 is connected to processing gas sources 70 and 72 of WF ₆ and SiH ₄ and a cleaning gas source 74 of ClF ₃ through a gas passage 68 and a plurality of branch paths, respectively. Flow control valves 70A, 72A, 74A and on-off valves 70B, 72B, 74B are interposed in the passages, respectively. Note that H ₂ gas can be used as the reducing gas instead of SiH ₄ .
[0019]
The side wall of the head main body 64 is provided with a water cooling jacket 80 as a cooling means formed by passing through the inside of the head main body 64 so as to cool the surface of the head main body 64, in particular, the surface opposite to the mounting table. It has become.
In the mounting table facing surface 64A, which is the lower surface of the head main body 64, a number of gas holes 76 for releasing the gas supplied into the head main body 64 are evenly arranged in the surface, and extend across the wafer surface. The gas is released evenly.
[0020]
Further, as shown in FIG. 2, a film deposition preventing film 78 which is a feature of the present invention that is difficult to deposit is formed on the mounting table facing surface 64A over the front surface, and the film is deposited. It has become difficult. As this film adhesion preventing film 78, for example, quartz (SiO ₂ ), alumina, or oxide such as alumite formed by treatment without using sodium can be used. In consideration of manufacturing cost, quartz is preferably used. Use. In this embodiment, quartz is used as the prevention film 78. As the quartz prevention film 78, for example, a thin film of quartz (SiO ₂ ) can be formed by an ion plating method using an aluminum head body 64 as an electrode, but the production method is not limited to this.
[0021]
When the prevention film 78 is formed, the diameter L1 of each gas hole 76 is relatively large as about 1.1 mm, whereas the thickness L2 of the prevention film 78 is as small as about 3 to 5 μm. There is no fear of being done.
Here, it is conceivable that the entire head main body 64 is made of quartz in order to prevent the deposition of the film, but in this case, quartz has a low thermal conductivity, so that the mounting table facing surface 64A is sufficiently cooled. This part cannot be performed and the part is heated more than necessary, and on the contrary, a lot of deposits are attached, which is not preferable. Therefore, in consideration of cooling efficiency, the head main body 64 is preferably formed of a material having good thermal conductivity such as aluminum described above.
[0022]
In the head main body 64, two diffusion plates 84 and 86 having a large number of gas dispersion holes 82 are arranged in two upper and lower stages, so that gas is supplied more evenly to the wafer surface. ing.
[0023]
Next, the operation of the present embodiment configured as described above will be described.
First, when a metal film is formed on the wafer surface, a gate valve (not shown) provided on the partition wall of the processing chamber 2 is opened, the wafer W is loaded into the processing chamber 2 by the transfer arm, and the lifter pins 18 are attached. By pushing up, the wafer W is transferred to the lifter pin 18 side. Then, the lifter pin 18 is lowered by lowering the push-up rod 22, and the wafer W is placed on the mounting table 4, and the push-up rod 22 is further lowered to press the peripheral edge of the wafer W with the clamp ring 30. To fix.
[0024]
Next, WF ₆ and SiH ₄ as processing gases are supplied from the processing gas sources 70 and 72 to the gas supply unit 62 and mixed, and are supplied evenly into the processing chamber 2 from the gas holes 62 on the lower surface of the head main body 62. To do. The supply amount of the gas at this time is, for example, WF ₆ is ₅ to 100 SCCM and SiH ₄ is 10 to 300 SCCM. At the same time, the inside atmosphere is sucked and exhausted from the exhaust port 50 to set the processing chamber to a predetermined vacuum level, for example, a value in the range of 1 Torr to 50 Torr, and the heating lamp 8 in the heating chamber 34 is not rotated. reluctant to drive dynamic, to radiate heat energy.
[0025]
The radiated heat rays pass through the transmission window 6 and then pass through the quartz support member 20 and the like to irradiate the back surface of the mounting table 4 and heat it. Since the mounting table 4 is very thin as about 1 mm as described above, the mounting table 4 is rapidly heated. Therefore, the wafer W mounted thereon can be rapidly heated to a predetermined temperature.
The supplied mixed gas causes a predetermined chemical reaction, and for example, a tungsten film is deposited on the wafer surface to be formed. At this time, since the lower surface of the head main body 64 of the shower head structure facing the wafer surface is also exposed to a relatively high temperature state, the deposited film tends to adhere to this portion.
[0026]
However, in this embodiment, since the film deposition prevention film 78 is formed in this portion, the film adhesion can be prevented. In particular, the effect of preventing film adhesion is effectively exerted on a metal oxide film such as WOx (tungsten oxide film) generated as a result of decomposition of moisture on the wafer surface introduced into the room as the wafer W is loaded. The
In such a film forming process, after processing one wafer, the wafer is discharged, a new unprocessed wafer is loaded, and film formation is performed again. Each time a batch, for example, 25 wafers is processed, ClF ₃ is introduced into the processing chamber 2 as a cleaning gas, and the inside of the processing chamber such as the lower surface of the head body 64 or the inner surface of the partition wall of the processing chamber 2 is introduced. The film deposited on the surface of the structure is removed by cleaning. Here, in this cleaning process, the metal film (W) and the metal silicide (WSi) can be removed relatively easily by the ClF _3, but the metal oxide film (WO _X ) is removed because it is stable. Is difficult.
[0027]
However, in this embodiment, since the film adhesion preventing film 78 made of, for example, SiO ₂ is formed as described above, the metal oxide film is difficult to adhere. Therefore, even if a large number of wafers are formed, the dry cleaning process using a normal cleaning gas such as ClF ₃ is sufficient, and the frequency of the decomposition wet cleaning operation accompanying the adhesion of the metal oxide film can be greatly reduced. Thus, the apparatus operating rate can be greatly improved.
[0028]
In particular, in the case of a blanket process for embedding irregularities on the wafer surface, rather than a film forming process for forming a wiring pattern, a film having a thickness of 8000 to 10,000 mm is formed on one wafer. The amount of deposits adhering to the lower surface of 64 increases, but among them, the amount of metal oxide film that is difficult to remove with ClF ₃ gas as described above is very small due to the action of the prevention film 78. Therefore, also in this case, the frequency of the wet cleaning work performed by disassembling the apparatus itself can be reduced, and the apparatus operating rate can be improved.
[0029]
When a comparative experiment between the conventional apparatus and the present invention apparatus was performed, when a film formation process of 1000 wafers was performed in the conventional apparatus and the lower surface of the head body was observed, yellow tungsten oxide was formed on one side. It was found that even when 1500 wafers were deposited in the apparatus of the present invention, tungsten oxide hardly adhered to the lower surface of the head body, and the initial state was maintained.
As described above, the film body adhesion preventing film 78 made of quartz or the like is formed on the mounting table facing surface 64A while the head body 64 is effectively cooled, so that it can be removed with a normal cleaning gas such as ClF ₃ gas. Therefore, it is possible to significantly suppress the adhesion of the metal oxide film, which is difficult to perform, and therefore the frequency of the wet cleaning process, which is a large-scale maintenance and inspection work, can be greatly reduced.
[0030]
In the above embodiment, the case where tungsten or tungsten silicide is formed as the metal film has been described. However, the present invention is not limited to this, and other metals such as Ti (titanium), TiN (titanium nitride), TiSi (titanium silicide) are used. The present invention can also be applied when a film is formed.
Further, in this embodiment, aluminum is used as the material of the head body 64 and the mounting table facing surface 64A is coated with, for example, a quartz film as a material that is difficult to deposit, but the entire head body 64 is deposited. hard material, may be formed, for example, alumina (Al ₂ O _3).
[0031]
Further, the portion covered with the film formation adhesion preventing film 78 is not limited to the surface opposite to the mounting table of the head main body, and the other structure in the processing chamber, for example, the inner surface of the partition wall that divides the processing chamber is also shown in FIG. Alternatively, it may be formed as shown by a one-dot chain line 88.
[0032]
【The invention's effect】
As described above, according to the film forming apparatus of the present invention, the following excellent effects can be exhibited.
A metal deposition preventive film is formed on the entire surface of the gas supply section, which is a structure in the processing chamber, that is, on the entire surface facing the mounting table of the shower head and on the partition wall that partitions the processing chamber. Oxide film formation can be suppressed.
Accordingly, it is possible to reduce the frequency of maintenance work on large-scale wet cleaning process or the like performed by disassembling the device itself in order to remove the metal oxide film, that amount is significantly improves the equipment utilization Rukoto Can do.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a film forming apparatus according to the present invention.
FIG. 2 is an enlarged cross-sectional view showing a gas supply unit of the apparatus shown in FIG.
FIG. 3 is a schematic cross-sectional view showing a general film forming apparatus for forming a metal thin film.
[Explanation of symbols]
2 Processing chamber 4 Mounting table 6 Transmission window 8 Heating means (heating lamp)
DESCRIPTION OF SYMBOLS 10 Shower head 12 Film-forming processing apparatus 18 Lifter pin 22 Push-up rod 30 Clamp ring 34 Heating chamber 54 Partition wall 62 of processing chamber Gas supply part 64 Head main body 64A Mounting table opposing surface 70, 72 Processing gas source 74 Cleaning gas source 76 Gas hole 78 Deposition prevention film 80 Water cooling jacket (cooling means)
W Semiconductor wafer (object to be processed)

Claims (7)

A metal film is provided on the surface of the object to be processed, comprising: a processing chamber having a mounting table for mounting the object to be processed; and a gas supply unit for supplying a processing gas into the processing chamber at a position facing the mounting table. Alternatively, in a film forming apparatus for forming a metal compound film,
The gas supply unit is made from a shower head having a large number of gas holes you release the gas into the processing chamber,
The shower head is formed of a metal having good thermal conductivity and a film containing aluminum oxide is formed on the surface thereof.
Means for maintaining the temperature of the shower head at a predetermined temperature;
A film forming apparatus, comprising: means for discharging a cleaning gas composed of a fluorine compound gas from the shower head into the processing chamber and cleaning the processing chamber. A metal film is provided on the surface of the object to be processed, comprising: a processing chamber having a mounting table for mounting the object to be processed; and a gas supply unit for supplying a processing gas into the processing chamber at a position facing the mounting table. Alternatively, in a film forming apparatus for forming a metal compound film,
  The gas supply unit comprises a shower head having a large number of gas holes for discharging gas into the processing chamber,
  Forming a partition wall defining the processing chamber with a metal having good thermal conductivity and forming a film containing aluminum oxide on the surface thereof;
  Means for maintaining the temperature of the partition wall at a predetermined temperature;
  An apparatus for forming a film, comprising means for discharging a cleaning gas made of a fluorine compound gas from the shower head into the processing chamber and cleaning the processing chamber. 3. The film forming apparatus according to claim 1, wherein the metal having good thermal conductivity is an aluminum alloy. The film forming apparatus according to claim 1, wherein the film containing aluminum oxide is alumite. The fluorine compound is ClF ₃ The film forming apparatus according to claim 1, wherein the film forming apparatus is a film forming apparatus. The film forming apparatus according to claim 1, wherein the metal film or the metal compound film contains tungsten or titanium. 7. The film forming apparatus according to claim 1, wherein the means for maintaining the predetermined temperature is a water cooling jacket .

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