Patent Application
20100272895
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2007-255780 filed on Sep. 28, 2007, the entire contents of which are incorporated herein by reference.
The present invention relates to a technique for supplying a process gas to a substrate, so as to deposit a film of reaction products of the process gas on the substrate.
As a film deposition method in a semiconductor manufacturing process, there has been known a method for depositing a film on a substrate, which makes, under vacuum atmosphere, a semiconductor wafer (hereinafter referred to as “wafer”), which is a substrate, adsorb a first process gas (material gas) on its surface, then switches a gas to be supplied from the first process gas to a second process gas (oxidizing gas) so as to form one or more atomic layers and molecular layers by the reaction of the first and second gases, and repeats this cycle plural times so as to stack these layers. This film deposition method, which is referred to as, e.g., an ALD (Atomic Layer Deposition) method or an MLD (Molecular Layer Deposition) method, can precisely control a film thickness depending on the number of cycles, and can provide an excellent film quality, i.e., a high in-plane uniformity. Thus, such a film deposition method is an effective method capable of coping with a thinner film of a semiconductor device.
For example, 3P2004-6733 A (particularly paragraph 0056 and FIG. 8) describes a film deposition apparatus for carrying out this film deposition method, wherein a film is deposited on a surface of a substrate placed in a process container (vacuum container) by alternately flowing two kinds of process gases from a left side surface of the process container to a right side surface thereof (or from the right side surface to the left side surface). When there is employed such a side flow method in which a process gas is flown from one side to the other side of a substrate, a lateral non-uniformity of a film thickness and of a film quality can be restrained. Thus, such a film deposition process can be performed under a relatively low temperature atmosphere such as about 200° C.
On the other hand, when a high dielectric constant material such as zirconium oxide (ZrO2) is deposited, for example, a TEMAZ (tetrakis ethyl methyl amino zirconium) gas is used as the first process gas (material gas), and an ozone gas is used as the second process gas (oxidizing gas). Since a decomposition temperature of the TEMAZ gas is high, a film deposition process is performed at a temperature as high as, e.g., 280° C. However, under this high temperature condition, since a reaction speed is accelerated, a film thickness of a film deposited during one cycle tends to be thicker. In particular, in the side flow method, since a moving distance of a gas on the surface of the substrate is long, there is a possibility that a film thickness might be large on a gas supply side, but might be small on an exhaust side. In this case, an excellent in-plane uniformity of the film thickness cannot be obtained.
In addition, when a supply time of an ozone gas as an oxidizing gas is reduced in order to improve a throughput, for example, an oxidation ability of the ozone gas becomes weaker as a supply point becomes distant from a supply source of the ozone gas (ozone gas is consumed). Thus, there is a possibility that the high dielectric constant material adsorbed on the substrate might not be oxidized in a sufficiently uniform manner. In this case, values of a leak current of semiconductor devices formed in the wafer may be deviated.
In order to solve the disadvantage of the side flow method, the following method is under review. Namely, by using a gas showerhead (see, JP2006-299294A (particularly paragraphs 0021 to 0026)) for use in a general CVD apparatus, for example, a process gas is supplied from above a central part of a substrate, and a non-reacted process gas and a reaction byproduct are discharged from a bottom part of a process container. In this gas supply and discharge method, the process gas to be supplied flows from the center of the substrate toward a periphery thereof. Thus, since a moving distance of the gas is shorter than that in the side flow method, a high in-plane uniformity of a film thickness and of a film quality of the deposited film can be expected after the film deposition.
In order to further improve properties of a film in a device, a material of the film itself and a material gas have been selected and developed. As a material for a high dielectric constant film used for a gate oxide film, the present inventors have taken notice of oxides containing strontium (Sr) and titanium (Ti). The use of three kinds of gases as material gases, i.e., a material gas containing Sr compound, a material gas containing Ti compound, and an oxidizing gas has been under review. When a film is deposited by the ALD method by using a gas showerhead as described above, the gas showerhead should be a showerhead of a post-mix type in which the respective gases are allocated to a number of gas supply holes formed in a gas supply surface, so that the three kinds of gases are independently jetted.
On the other hand, in order to cope with the demand for thinner film, higher degree of integration, and higher performance of a semiconductor device, an excellent in-plane uniformity of a film thickness and of a film quality is required. Thus, how such an excellent in-plane uniformity is achieved should be researched, when the three kinds of gases are used.
JP2005-723A (see, paragraph 0052 and FIG. 4) describes a gas supply system wherein a gas supply surface of a gas showerhead is divided into unit zones formed of regular triangles of the same size, and gas supply holes are positioned on three apexes of each regular triangle constituting the unit zone. However, JP2005-723A does not describe the above object at all.
The present invention has been made in view of the aforementioned circumstances. The object of the present invention is to provide a film deposition apparatus, a film deposition method, a storage medium storing this method, and a gas supply apparatus, capable of achieving an excellent in-plane uniformity of a film thickness and of a film quality, when three kinds of process gases are supplied to a substrate from a gas supply surface opposed to the substrate so as to deposit a film on the substrate.
A film deposition apparatus of the present invention comprising:
a process container;
a table on which a substrate can be placed, the table being disposed in the process container; and
a gas showerhead disposed so as to be opposed to the table, the gas showerhead including a gas supply surface having a first gas supply hole for supplying a first process gas, a second gas supply hole for supplying a second process gas, and a third gas supply hole for supplying a third process gas;
wherein:
the gas supply surface is divided into unit zones formed of regular triangles of the same size, and the first gas supply hole, the second gas supply hole, and the third gas supply hole are disposed on respective three apexes of each regular triangle constituting the unit zone; and
the first process gas, the second process gas, and the third process gas differ from each other, and a film is deposited on a surface of the substrate by reacting the first process gas, the second process gas, and the third process gas with each other.
In the film deposition apparatus of the present invention, it is preferable that
the first process gas supplied from the first gas supply hole contains a strontium compound;
the second process gas supplied from the second gas supply hole contains a titanium compound;
the third process gas supplied from the third gas supply hole is an oxidizing gas reactable with the strontium compound and the titanium compound; and
the film to be deposited on the surface of the substrate is made of strontium titanate.
In the film deposition apparatus of the present invention, it is preferable that
the oxidizing gas is an ozone gas or a steam.
A film deposition method of the present invention comprising the steps of:
placing a substrate on a table disposed in a process container; and
supplying gases from a gas showerhead disposed so as to be opposed to the table, the gas showerhead being divided into unit zones formed of regular triangles of the same size, with a first gas supply hole, a second gas supply hole, and a third gas supply hole being disposed on respective three apexes of each regular triangle constituting the unit zone;
wherein:
the step of supplying gases includes a first process-gas supplying step for supplying the first process gas, a second process-gas supplying step for supplying the second process gas, and a third process-gas supplying step for supplying the third process gas; and
the first process gas, the second process gas, and the third process gas differ from each other, and a film is deposited on a surface of the substrate by reacting the first process gas, the second process gas, and the third process gas with each other.
In the film deposition method of the present invention, it is preferable that
the first process gas supplied in the first process-gas supplying step contains a strontium compound;
the second process gas in the second process-gas supplying step contains a titanium compound;
the third process gas supplied in the third process-gas supplying step is an oxidizing gas reactable with the strontium compound and the titanium compound; and
the film made of strontium titanate is deposited on the surface of the substrate.
In the film deposition method of the present invention, it is preferable that
the oxidizing gas is an ozone gas or a steam.
A storage medium of the present invention storing a computer program for causing a film deposition apparatus to perform a film deposition method that comprises the steps of:
placing a substrate on a table disposed in a process container; and
supplying gases from a gas showerhead disposed so as to be opposed to the table, the gas showerhead being divided into unit zones formed of regular triangles of the same size, with a first gas supply hole, a second gas supply hole, and a third gas supply hole being disposed on respective three apexes of each regular triangle constituting the unit zone;
wherein:
the step of supplying gas includes a first process-gas supplying step for supplying the first process gas, a second process-gas supplying step for supplying the second process gas, and a third process-gas supplying step for supplying the third process gas; and
the first process gas, the second process gas, and the third process gas differ from each other, and a film is deposited on a surface of the substrate by reacting the first process gas, the second process gas, and the third process gas with each other.
A gas supply apparatus of the present invention comprising:
a first introduction port for introducing a first process gas;
a second introduction port for introducing a second process gas;
a third introduction port for introducing a third process gas;
a first gas supply hole for supplying the first process gas introduced from the first introduction port to a substrate;
a second gas supply hole for supplying the second process gas introduced from the second introduction port to the substrate;
a third gas supply hole for supplying the third process gas introduced from the third introduction port to the substrate; and
a gas conduit structure part configured such that the first process gas introduced from the first introduction port, the second process gas introduced from the second introduction port, the third process gas introduced from the third introduction port, are respectively jetted from the first gas supply hole, the second gas supply hole, and the third gas supply hole, independently;
wherein:
the first gas supply hole, the second gas supply hole, and the third gas supply hole are disposed in a gas supply surface;
the gas supply surface is divided into unit zones formed of regular triangles of the same size, and the first gas supply hole, the second gas supply hole, and the third gas supply hole are disposed on respective three apexes of each regular triangle constituting the unit zone; and
the first process gas, the second process gas, and the third process gas differ from each other, and a film is deposited on a surface of the substrate by reacting the first process gas, the second process gas, and the third process gas with each other.
In the present invention, the gas supply surface is divided into the unit zones formed of regular triangles of the same size. The first process gas, the second process gas, and the third process gas are supplied from the three apexes of each regular triangle. Thus, the three gas supply holes for jetting the first to third process gases exist in every regular triangle, and the three gas supply holes are arranged with equal intervals therebetween. Thus, when a film is deposited by the CVD method in which the first to third processing gases are jetted simultaneously or by the so-called ALD method in which those gases supply timings differ from each other, an excellent in-plane uniformity of a film thickness and of a film quality can be obtained.
At first, an overall structure of the film deposition apparatus 1 in this embodiment is described with reference to
The first process gas, the second process gas, and the third process gas differ from each other, and a thin film can be deposited on a surface of the wafer W by reacting these first process gases, the second process gas, and the third process gas with each other. For example, a material gas containing strontium (Sr) (hereinafter referred to as “Sr material gas”) may be used as the first process gas, a material gas containing titanium (Ti) (hereinafter referred to as “Ti material gas”) may be used as the second process gas, and an ozone gas which is an oxidizing gas may be used as the third process gas. By reacting the Sr material gas, the Ti material gas, and the ozone gas with each other, a film made of strontium titanate (SrTiO3 (hereinafter abbreviated to “STO”), which is a high dielectric constant material, can be deposited on a surface of the wafer W by the ALD method.
The table 3 is composed of a stage 31 corresponding to a table body for supporting the wafer W, and a stage cover 32 for covering the stage 31. The stage 31 is made of aluminum nitride or quartz, and is formed to have a flat discoid shape. Embedded in the stage 31 is a stage heater 33 configured to heat a table surface of the table 3, so as to heat the wafer W to a film deposition temperature. The stage heater 33 is formed of, e.g., a sheet-like heating resistor, and is capable of heating the wafer W placed on the table 3 to, e.g., 280° C., by means of an electric power supplied from a power supply part 68. Further, an electrostatic chuck, not shown, is disposed in the stage 31. Thus, the wafer W placed on the table 3 can be electrostatically fixed.
On the other hand, the stage cover 32 constituting the table 3 together with the stage 31 has a function for preventing deposit of reactants such as reaction products and reaction byproducts onto the surface of the stage 31, by covering an upper surface and a side surface of the stage 31. The stage cover 32 is structured as a quartz removable cover member (called “deposit shield” or the like). A circular recess whose diameter is slightly larger than that of the wafer W is formed in a central area of an upper surface of the stage cover 32. Thus, the wafer W can be easily placed in position on the table surface above the stage cover 32.
The stage 3 is supported by a columnar support member 34 on a lower central part of the stage 31. The support member 34 is adapted to be vertically moved (moved upward and downward) (elevated and lowered) by an elevating mechanism 69. By vertically moving the support member 34, the table 3 can be vertically moved along a distance of 80 mm at maximum, between a transport position at which the wafer W is transported to and from an external transport mechanism, and a process position at which the wafer W is processed.
As shown in
In addition, the table 3 has a plurality of, e.g., three elevating pins 35 for vertically moving the wafer W on the table surface of the table 3 while supporting a rear surface of the wafer W. For example, as shown in
A ring-shaped elevating member 36 is disposed below the elevating pins 35 passing through the stage 31. In a state where the table 3 is lowered and located at the transport position for the wafer W, by vertically moving the elevating member 36 so as to vertically move the respective elevating pins 35, the wafer W supported by the elevating pins 35 can be vertically moved above the table surface of the table 3.
Openings for receiving the head parts of the elevating pins 35 are formed in the upper surface of the stage cover 32 at positions where the elevating pins 35 pass through. Thus, as shown in
Next, a structure of the process container 2 is described. The process container 2 in this embodiment includes the flat bowl-like lower container 22, and an annular exhaust duct 21 superposed on the lower container 22. The lower container 22 is made of, e.g., aluminum. The lower container 22 has a through hole 221 in a bottom surface thereof, through which the support member 34 of the stage 31 can pass. A plurality of, e.g., four purge-gas supply conduits 222 are disposed around the through hole 221. Thus, a purge gas such as a nitrogen gas supplied from a purge-gas supply source 66 can be sent into the lower container 22. In
The exhaust duct 21 is an annular member formed by curving an aluminum rectangular duct, for example. An inside diameter and an outside diameter of the annular body are substantially the same as an inside diameter and an outside diameter of the sidewall part 223 of the lower container 22. A wall surface of the exhaust duct 21, which is closer to the process atmosphere, is referred to as an inner wall surface, and a wall surface thereof, which is more distant from the process atmosphere, is referred to as an outer wall surface. In an upper end part of the inner wall surface, there are circumferentially arranged a plurality of vacuum exhaust ports 211, which are laterally extending slit-like exhaust ports, with intervals therebetween. An exhaust pipe 29 is connected to the outer wall surface of the exhaust duct 21 at one certain position, for example. By using a vacuum pump 67 connected to the exhaust pipe 29, for example, a gas can be discharged from the vacuum exhaust ports 211 so as to create a vacuum. As shown in
The exhaust duct 21 having the aforementioned structure is superposed on the lower container 22 via the heat insulation member 212. The exhaust duct 21 and the lower container 22, which are thermally insulated from each other, integrally constitute the process container 2. Since the plurality of vacuum exhaust ports 211 formed in the inner wall surface of the exhaust duct 21 are opened to a space including a process atmosphere 10, which is formed between the gas showerhead 4 and the table 3, the process atmosphere 10 can be discharged through the vacuum exhaust ports 211 to create a vacuum.
As shown in
As shown in
In addition, a baffle ring 27 is disposed between the vacuum exhaust ports 211 formed in the inner wall surface of the exhaust duct 21 and the process atmosphere 10. The baffle ring 27 is a member having an inverted L-shape section, for lowering a flow conductance, to thereby allow the process container 2 to be uniformly exhausted in a circumferential direction thereof when viewed from the process atmosphere 10.
Next, the gas showerhead 4 is described.
A supply structure of the process gases in the central area is described at first. As shown in
Arrangement of the respective introduction ports 51a to 54a in the upper surface of the gas showerhead 4 is described. As shown in
The first introduction port 51a is in communication with the first diffusion space 421 through a first gas introduction conduit 511. As described below, the gas showerhead 4 is structured by stacking four plates. The first gas introduction conduit 511 is formed vertically to the uppermost plate 41 of the plate group.
The second introduction ports 52a are in communication with the second diffusion space 422 through second gas introduction conduits 521. The third introduction ports 53a are in communication with the third diffusion space 431 through third gas introduction conduits 531. The second gas introduction conduits 521 extend vertically from the uppermost plate 41 through the second diffusion space 421. Thus, in the first diffusion space 421, there are arranged small cylindrical parts 423 whose inside spaces form the second gas introduction conduits 521. The third gas introduction conduits 531 extend from the uppermost plate 41 to the third diffusion space 431 such that positions of the third gas introduction conduits 531 in a planar direction are located outside the first diffusion space 421 and the second diffusion space 422.
Further, disposed between a bottom surface of the first diffusion space 421 and the gas supply surface 40a of a lower surface of the gas showerhead 4 are a number of vertical first gas supply conduits 512 whose upper and lower ends are opened to the bottom surface and the gas supply surface 40a. The first gas supply conduits 512 pass through the second diffusion space 422 and the third diffusion space 431. Thus, in parts of the diffusion spaces 422 and 431, through which the first gas supply conduits 512 pass, there are respectively arranged small cylindrical parts 425 and 432 whose inside spaces form the first gas supply conduits 512.
Furthermore, disposed between a bottom surface of the second diffusion space 422 and the gas supply surface 40a of the lower surface of the gas showerhead 4 are a number of vertical second gas supply conduits 522 whose upper and lower ends are opened to the bottom surface and the gas supply surface 40a. The second gas supply conduits 522 pass the third diffusion space 431. Thus, in parts of the third diffusion space 431, through which the second gas supply conduits 522 pass, there are arranged small cylindrical parts 433 whose inside spaces form the second gas supply conduits 522.
Still furthermore, disposed between a bottom surface of the third diffusion space 431 and the gas supply surface 40a of the lower surface of the gas showerhead 4 are a number of vertical third gas supply conduits 532 whose upper and lower ends are opened to the bottom surface and the gas supply surface 40a. Regarding the name of each gas conduit, the gas conduit extending from the introduction port to the diffusion space is referred to as “gas introduction conduit”, and the conduit extending from the diffusion space to the lower surface of the gas showerhead 4 is referred to as “gas supply duct”.
Since the central area of the gas showerhead 4 is as structured above, by respectively introducing the Sr material gas, the Ti material gas, and the ozone gas to the first introduction port 51a, the second introduction port 52a, and the third introduction port 53a, these gases pass through the conduits that are independent from each other, and then the gases are supplied from the gas supply surface 40a of the lower surface of the gas showerhead 4 to a central area 10a of the process atmosphere 10 shown in
Next, a supply structure of the process gas in the peripheral area of the gas showerhead 4 is described. As described above, the two fourth introduction ports 54a are disposed in the area outside the central area in the upper surface of the gas showerhead 4 at the opposed positions with the center of the gas showerhead 4 being interposed therebetween. In the peripheral area, a ring-like fourth diffusion space 411 is formed at a position higher than the first diffusion space 421. In order to introduce a gas from the two fourth introduction ports 54a to the fourth diffusion space 411, fourth gas introduction conduits 541, which vertically extend, are formed. A ring-like fifth diffusion space 441 is formed in a lower projection area of the fourth diffusion space 411 at a position lower than the third diffusion space 431. Two fifth gas introduction conduits 542, which vertically extend, are formed to allow a gas to flow from the fourth diffusion space 411 to the fifth diffusion space 441.
The upper fourth gas introduction conduits 541 and the lower fifth gas introduction conduits 542 are alternately shifted by 90 degrees in the circumferential direction of the gas showerhead 4. Disposed between a bottom surface of the fifth diffusion space 441 and the gas supply surface 40b of the lower surface of the gas showerhead 4 are a number of vertical fourth gas supply conduits 543 whose upper and lower ends are opened to the bottom surface and the gas supply surface 40b.
Due to the structure of the peripheral area of the gas showerhead 4, by introducing the purge gas to the fourth introduction ports 54a, the purge gas can be supplied from the peripheral area 10b, which is outside the central area 10a for supplying the process gases, in the gas supply surface 40b of the lower surface of the gas showerhead 4.
As shown in
The first plate 41 has a flange part 41a on an upper periphery thereof. As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
In the diffusion spaces 422 and 431, owing to the existence of the plurality of cylindrical parts 425, 432, and 433, heat is transferred through these parts. However, since the number of cylindrical parts 423 in the diffusion space 421 is smaller, a columnar part 424 projecting upward from the bottom surface of the recess to the upper plate is disposed at a location other than the aforementioned cylindrical parts 423, in order that heat can be easily transferred between the upper and lower plates 41 and 42.
Upper end surfaces or lower end surfaces of the cylindrical parts 423, 425, 432, and 433 and the columnar part 424 are coplanar with (positioned at the same height) the surfaces of the plates 42 and 43 other than the recesses. Thus, the upper end surfaces of the lower end surfaces of the cylindrical parts 423, 425, 432, and 433 are sealingly in contact with the surfaces of the opposed plates 41, 43, and 45, whereby a gas flowing through the cylindrical parts 423, 425, 432, and 433 can be prevented from leaking into the gas diffusion spaces 421, 422, and 432. Hereabove, the aforementioned gas diffusion spaces 421, 422, 431, 411, and 441, the gas introduction conduits 511, 521, 531, 541, and 542, and the gas supply conduits 512, 522, 532, and 543, which are disposed in the respective plates 41 to 45, constitute a gas conduit structure part for independently supplying the first to third process gases (Sr material gas, Ti material gas, and ozone gas) to the process atmosphere.
Larger diameter parts are formed at positions where the gas introduction conduits 511, 521, 541, and 542 are opened to the gas diffusion spaces 421, 422, 411, and 441. In detail, as shown in
As shown in
Bolt holes 81a to 84a and 81b to 84b are drilled in the respective plates 41 to 45 of the gas showerhead 4 such that the plates 41 to 45 are fastened to each other.
As shown in
In detail, the Sr-material supply line 610 is connected to the Sr-material supply source 61 that stores a liquid Sr material such as Sr(THD)2 (strontium bistetra methyl heptanedionato) and Sr(Me5 Cp)2 (bis pentamethyl cyclopenta dienyl strontium). The Sr material is extruded to the supply conduit, and is evaporated by an evaporator 611. Then, the evaporated Sr material is supplied to the Sr-material supply line 610.
The Ti-material supply line 620 is connected to the Ti-material supply source 62 that stores a Ti material such as Ti(OiPr)2(THD)2 (titanium bis-isopropoxide bistetra methyl heptanedionato) and Ti(OiPr) (titanium tetra isopropoxide). Similarly to the Sr material, the Ti material is extruded to the supply conduit, and is evaporated by an evaporator 621. Then, the evaporated Ti material is supplied to the Ti-material supply line 620.
The ozone-gas supply line 630 is connected to the ozone-gas supply source 63 formed of, e.g., a well-known ozonizer. The purge-gas supply line 640 is connected to the purge-gas supply source 64 formed of an argon-gas cylinder. Thus, an ozone gas and an argon gas can be supplied to the respective supply lines 630 and 640. The respective Sr-gas supply line 610, the Ti-material supply line 620, and the ozone-gas supply line 630 are branched, and the respective branched conduits are connected to the purge-gas supply source 64. Thus, a purge gas, instead of the respective process gases, can be supplied from the respective gas supply lines 610 to 630. In addition, disposed between the gas supply lines 610 to 640 and the gas supply sources 61 to 64 is a flow-rate controller group 65 composed of valves and flowmeters. Thus, based on a command from a control device 7, which will be described below, supply rates of the respective gases can be controlled. Although the respective gas supply lines 610 to 640 are connected to all the eleven introduction ports 51a to 52 shown in
Returning to the description of the apparatus structure of the film deposition apparatus 1, as shown in
The film deposition apparatus 1 as described above is equipped with the control device 7 that controls a gas supply operation from the aforementioned gas supply sources 61 to 63, a vertical movement of the stage 31, an exhaust operation in the process container 2 by the vacuum pump 67, and a heating operations of the respective heaters 47 and 213. The control device 7 is formed of a computer, not shown, including a CPU and a program. The program has a step (command) group required for the film deposition apparatus 1 to control the respective members so as to perform a film deposition process to a wafer W, for example, to perform a control of gas supply and stop timings and supply rates of the respective gases from the gas supply sources 61 to 64, an adjustment of a vacuum degree in the process container 2, control of a vertical movement of the stage 31, and a control of temperatures of the respective heaters 47 and 213. Such a program is stored in a storage medium such as a hard disc, a compact disc, a magnetoptical disc, and a memory card, and is generally installed on the control device 7 from the storage medium.
In the film deposition apparatus 1 having the above-described apparatus structure, the arrangement of the gas supply holes for the respective gases formed in the gas supply surface 40a of the gas showerhead in this embodiment is determined such that, when an STO film is deposited with the use of the three kinds of gases, i.e., the Sr material gas, the Ti material gas, and the ozone gas, an excellent in-plane uniformity of a film thickness and of a film quality of the STO film can be achieved. Herebelow, details of the arrangement is described with reference to
As in this embodiment, in the gas showerhead 4 that deposits a film by supplying a process gas to a wafer W opposed thereto from the plurality of gas supply holes 51b to 53b formed in the gas supply surfaces 40a, intervals (hereinafter referred to as “pitches”) between the gas supply holes 51b to 53b, and a distance (hereinafter referred to as “gap”) between the surface of the wafer W placed on the table 3 and the gas supply surface 40a of the gas showerhead 4, exert an effect on an in-plane uniformity of a film quality and of a film thickness.
Namely, as shown in
The transfer of the gas supply holes 50b occurs as the value of the pitch a increases (in proportion to the value of the pitch a). In addition, the transfer of the gas supply holes 50b occurs when the value of the gap h is too large and too small. Thus, in order to obtain a film F having a uniform film thickness without transfer, it is preferable to perform a film deposition process under conditions where the pitch a is sufficiently small with the suitable gap h, which is shown in
As described above with reference to
In the film deposition apparatus 1 in this embodiment, as has been described with reference to
From this point of view, as shown in
Namely, in the arrangement technique shown in
As shown in
Another arrangement technique shown in
Similarly to the arrangement in this embodiment shown in
When a film deposition is performed by using a gas showerhead having the gas supply surface 40a in which the smaller pitches a1 and the larger pitches a2 exist in a mixed manner, as in the above-described arrangement technique, there exist areas whose degree of transfer of the gas supply holes 51b to 53b to the deposited film is large, and areas whose degree of the transfer is small, in a mixed manner. However, in general, a uniformity of a film thickness is evaluated with the use of a maximum value of a difference between an average value of the film thickness and the actual film thickness. Thus, the evaluation of the uniformity of the film thickness of the overall film is performed in the area whose degree of transfer is large. Thus, as compared with the arrangement technique shown in
The arrangement techniques shown in
On the other hand, the influence of the other arrangement technique is similarly examined for the four unit zones 402 surrounding the certain Sr-material gas supply hole 51b. For example, the two ozone-gas supply hole 53b, i.e., the left and below ozone-gas supply holes 53b with respect to the central Sr-material gas supply hole 51b are distant therefrom by the distance l, while the upper right ozone-gas supply hole 53b with respect to the central Sr-material gas supply hole 51b is distant therefrom by the distance (√{square root over (2)}l). Namely, the distances from the Sr-material gas supply hole 51b differ from each other. Thus, in the area of the wafer W positioned below the Sr-material gas supply hole 51, the timings at which the gas supplied from these supply holes 53b reaches the area of the wafer W and the adsorption periods differ from each other in the upper right part and the left below part of the area. For example, there is a possibility that a gas adsorption density might be non-uniform, i.e., the gas adsorption density might be low in the upper right part of the area, while the gas adsorption density might be high in the lower left part. Meanwhile, regarding the three Ti-material gas supply holes 52b surrounding the central Sr-material gas supply hole 51b, since the arrangement state thereof is a state that is obtained by rotating the arrangement state of the ozone-gas supply holes 53b by 180°. Thus, there is a possibility that the gas adsorption density might be non-uniform, i.e., the gas adsorption density might be low in the lower left part of the area, while the gas adsorption density might be high in the upper right part.
When the adsorption amounts of the three kinds of gases become larger and smaller because of the non-uniform arrangement state, it is impossible to combine strontium atoms, titanium atoms, and oxygen atoms at a ratio of 1:1:3. In this case, there is a possibility that strontium oxide (SrO) and titanium oxide (TiO2) might be mixed in the STO film, whereby an STO film having a uniform film quality cannot be obtained.
According to the aforementioned arrangement technique of the gas holes shown in
As shown in
At this time, as described above, the inner block 26 is fixed at the position higher than the transport position for the wafer W. Thus, as shown in
After the pressure in the process container 2 is reduced to a predetermined value, the table 3 on which the wafer W has been placed is elevated to the process position which selected in accordance with the recipes, i.e., to the process position at which the gap h is 8 mm, while the vacuum evacuation is continued. As shown in
After the process atmosphere 10 and the space inside the lower container 22 have been separated from each other, there is started introduction of the purge gas into the lower container 22 through the purge-gas supply conduits 222. Then, a temperature of the wafer W is heated to, e.g., 280° C. by the stage heater 33. Thereafter, an STO film deposition process is started. In
The STO film deposition process by the ALD method is performed based on a gas supply sequence shown in
As shown in
In this manner, the Sr material gas is supplied from the central area of the gas supply surface 40a of the gas showerhead 4 to the process atmosphere 10 and reaches the central part of the wafer W placed on the table 3. At this time, as shown in
As shown in
After a predetermined time has passed and the adsorption layer of the material gases has been formed on the wafer W, the supply of the material gases is stopped. As shown in
Since the purge gas is simultaneously supplied to both the central area 10a and the peripheral area 10b of the process atmosphere 10 in the process container 2, a larger amount of the purge gas is supplied as compared with a case in which the purge gas is supplied from only one of these areas. Thus, the material gas can be purged for a shorter time. At this time, as shown in
After the purge of the Sr material gas from the process atmosphere 10 is finished, as shown in
Then, as shown in
After the supplying steps and the purging steps of the Sr material gas and the Ti material gas, as shown in
As a result, the ozone gas reaching the surface of the wafer W in the process atmosphere 10 reacts with the material gases which have been already adsorbed on the surface of the wafer W, by a heat energy from the stage heater, whereby an STO molecular layer is formed. After the ozone gas has been supplied for a predetermined time, the supply of the ozone gas is stopped. Then, as shown in
As shown in
In the present invention, the gas supply surface 40a is divided into the unit zones 401 formed of regular triangles of the same size. The Sr material gas (first process gas), the Ti material gas (second process gas), and the ozone gas (third process gas) are supplied from the three apexes of each regular triangle. Thus, the three gas supply holes 51b to 53b for jetting the first to third process gases exist in every regular triangle, and the three gas supply holes 51b to 53b are arranged with equal intervals therebetween. Thus, when a film is deposited by the so-called ALD method in which gas supply timings differ from each other, an excellent in-plane uniformity of a film thickness and of a film quality can be obtained.
In addition, even when the first to third process gases are simultaneously jetted as described above, it is possible to adsorb these gases in a uniform state. Thus, the arrangement of the gas supply holes 51b to 53b in this embodiment is not limited to the ALD method, but can be applied to a gas showerhead of a film deposition apparatus that deposits a film by simultaneously jetting the first to third gas by a CVD method.
In the above-described film deposition apparatus 1, there has been described the case in which an STO film is deposited by reacting the Sr material gas (first process gas) and Ti material gas (second process gas), which are used as material gases, with the ozone gas (third process gas) as an oxidizing gas. However, the kind of a film capable of being deposited by the film deposition apparatus 1 is not limited to the STO film. For example, a steam (water vapor), instead of the ozone gas described in the embodiment, may be employed as an oxidizing gas. Alternatively, the present invention may be applied to a process for depositing a barium titanate (BaTiO3) film, by reacting a first process gas containing a barium compound and a second process gas containing a titanium compound, with an oxidizing gas as a third process gas.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-255780 | Sep 2007 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/066455 | 9/11/2008 | WO | 00 | 6/15/2010 |
