JP2013048227A - Shower head device and deposition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shower head device which enables high in-plane uniformity of the film thickness.SOLUTION: A shower head device 46, introducing a gas into a processing container 4 housing a workpiece W on which a thin film is formed, has a shower head body 50 where a gas diffusion chamber 48, diffusing the gas, is formed therein; and multiple gas jet holes 54 provided on a gas jet plate 52 of the shower head body. The multiple gas jet holes are arranged along multiple spiral curve lines 84, each of which is virtually formed with a center part of the gas jet plate located at the center. This structure uniformly diffuses the gas in the planar direction and improves the in-plane uniformity of the film thickness.

Description

  The present invention relates to a shower head device and a film forming apparatus for forming a thin film on the surface of an object to be processed such as a semiconductor wafer.

  In general, in order to manufacture a semiconductor device or the like, various processes such as a film forming process, an etching process, and an annealing process are repeatedly performed on an object to be processed such as a semiconductor wafer. For example, in the case of a single wafer type film forming apparatus that processes semiconductor wafers one by one, a semiconductor wafer is placed in a processing container that can be evacuated and heated while the wafer is heated. Various film forming gases are ejected from the gas ejection holes of the shower head provided in the substrate, thereby depositing a thin film of a desired film type on the surface of the wafer.

  Recently, there has been a demand for further higher integration and miniaturization of semiconductor devices. Along with this, the thin film itself is made thinner and the in-plane uniformity of the film thickness is further improved. It is demanded to make it.

  As described above, in order to improve the in-plane uniformity of the film thickness, various studies have been made on optimizing the arrangement, shape, size, and the like of the gas injection holes of the showerhead (for example, Patent Documents). 1, 2, 3). For example, in Patent Document 1, the gas injection holes are arranged on multiple circumferences or in a spiral shape, in Patent Document 2, the gas injection holes are arranged in a spiral shape, and in Patent Document 3, the shower head is formed by a partition member. A large number of gas flow paths formed in a shape are formed, and gas is supplied from the slit-shaped gas injection holes, which are the outlets, into the processing container.

Japanese Patent Laid-Open No. 03-248431 JP 2009-152603 A JP 2009-239082 A

  However, in the conventional shower head as described above, it is difficult to say that the arrangement and shape of the gas injection holes are sufficiently optimized, and the in-plane uniformity of the film thickness is inferior. there were. Particularly recently, as a method for supplying a film forming gas as in the case of forming a high dielectric constant (high-k) thin film using an organic metal material, a source gas and a reactive gas such as ozone (oxidizing gas) ) Are intermittently and repeatedly supplied to each other, and a so-called ALD (Atomic Layer Deposition) method is employed in which thin films having a thickness of atomic level or molecular level are stacked.

  In this ALD method, the gas switching in the shower head and the processing vessel must be performed in a short time of about several seconds as described above. However, the conductance of the shower head can be increased while maintaining high in-plane film thickness uniformity. It was difficult to switch the gas quickly at a high value.

  The present invention has been devised to pay attention to the above problems and to effectively solve them. The present invention is a shower head apparatus and a film forming apparatus capable of increasing in-plane uniformity of film thickness.

According to the shower head apparatus and the film forming apparatus according to the present invention, the following excellent operational effects can be exhibited.
In a showerhead apparatus that introduces gas into a processing container that accommodates an object to be processed on which a thin film is formed, the gas can be supplied in a uniformly dispersed manner in the processing space. Therefore, the in-plane uniformity of the film thickness formed on the object to be processed can be improved.

It is a cross-sectional block diagram which shows the film-forming apparatus using the shower head apparatus which concerns on this invention. It is a top view which shows the lower surface of the gas injection plate of a shower head apparatus. It is an expanded sectional view which shows the A section in FIG. It is a figure for demonstrating arrangement | positioning of the gas injection hole of a gas injection plate. It is a timing chart which shows an example of the timing of supply of each gas. It is a figure which shows the aspect of the spiral used for the deformation | transformation Example of a shower head apparatus.

  Hereinafter, an example of a shower head device according to the present invention and a film forming apparatus using the same will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing a film forming apparatus using a shower head device according to the present invention, FIG. 2 is a plan view showing a lower surface of a gas injection plate of the shower head device, and FIG. 3 shows a portion A in FIG. FIG. 4 is an enlarged cross-sectional view, and FIG. 4 is a view for explaining the arrangement of gas injection holes of the gas injection plate.

  As shown in FIG. 1, a film forming apparatus 2 according to the present invention includes a processing container 4 formed into a cylindrical shape from, for example, aluminum, aluminum alloy, stainless steel, or the like. The bottom portion 6 of the processing container 4 is formed such that its center portion is recessed downward so as to protrude downward, and an exhaust port 8 is provided on the bottom side wall.

  The exhaust port 8 is provided with a vacuum exhaust system 10 that exhausts the atmosphere in the processing container 4. Specifically, the vacuum exhaust system 10 has an exhaust passage 12 connected to the exhaust port 8. In the exhaust passage 12, a pressure adjusting valve 14 and a vacuum pump 16 for sequentially adjusting the pressure in the processing container 4 are provided in order from the upstream side to the downstream side.

  And in this processing container 4, the holding means 18 which hold | maintains the to-be-processed object, for example, the semiconductor wafer W is provided. Here, the holding means 18 has a support column 20 erected at the center of the bottom 6 of the processing container 4, and a mounting table 22 having a disk shape is provided at the upper end of the support column 20. The semiconductor wafer W is mounted on the mounting table 22. The diameter of the semiconductor wafer W is set to 300 mm, for example.

  The mounting table 22 is formed of, for example, a ceramic material such as AlN, an aluminum alloy, or the like, and a heating unit 24 for heating the semiconductor wafer W is provided therein. As the heating means 24, for example, a resistance heater such as a carbon wire heater is used so that the wafer temperature can be controlled. A heating lamp may be used as the heating means 24.

  The mounting table 22 is provided with a lifter mechanism 25 that lifts or lifts the wafer W when the semiconductor wafer W is loaded and unloaded. The lifter mechanism 25 has a plurality of elevating pins 28 that are moved up and down in through holes 26 provided in the periphery of the mounting table 22, and the lower ends of the elevating pins 28 are supported by an elevating ring 30. Yes.

  Then, by moving the lifting ring 30 up and down by a lifting rod 34 provided penetrating the bottom 6 of the processing container 4 via a bellows 32, the lifting pin 28 is caused to appear above and below the upper surface of the mounting table 22. The wafer W can be lifted or lowered. The lifting rod 34 is lifted and lowered by an actuator 36 provided at the lower end portion. A plurality of, for example, three (e.g., only two are shown in the drawing) are provided as the lifting pins 28 along the circumferential direction of the mounting table 22.

  A loading / unloading port 38 for loading / unloading the wafer W is provided on the side wall of the processing container 4, and a gate valve 40 is provided at the loading / unloading port 38 that is opened and closed airtightly when the wafer is loaded / unloaded. A ceiling plate 44 is provided on the ceiling of the processing container 4 via a sealing member 42 such as an O-ring. A shower head device 46 according to the present invention for introducing gas into the processing container 4 is provided on the ceiling plate 44 so as to face the mounting table 22.

  Specifically, the shower head device 46 includes a shower head main body 50 in which a gas diffusion chamber 48 for diffusing gas is formed, and a plurality of gas injection plates 52 provided on the lower surface of the shower head main body 50. The gas injection hole 54 is mainly configured. The ceiling plate 44 is formed as a part of a shower head body 50 that defines the gas diffusion chamber 48, and the ceiling plate 44 is formed with a gas inlet 56 for introducing various gases. A plurality of gas inlets 56 may be provided according to the gas type.

  Various gas supply systems necessary for film formation are connected to the gas inlet 56. Specifically, here, the source gas supply system 60, the reaction gas supply system 62, and the purge gas supply system 64 are connected so that each gas flows while controlling the flow rate as necessary. The source gas supply system 60 has a gas passage 66 connected to the gas inlet 56. The gas passage 66 is sequentially provided with an on-off valve 68 and a flow rate controller 70 such as a mass flow controller so that the source gas is allowed to flow intermittently while controlling the flow rate as will be described later. Here, for example, tetrakis (ethylmethylamino) hafnium (TEMAHf), which is an organic metal material containing hafnium metal, is used as the source gas.

The reaction gas supply system 62 has a gas passage 72 connected to the gas inlet 56. The gas passage 72 is sequentially provided with an on-off valve 74 and a flow rate controller 76 such as a mass flow controller so that the reaction gas is allowed to flow intermittently while controlling the flow rate as will be described later. Here, as the reaction gas, for example, water vapor (H ₂ O) which is an oxidizing gas is used.

The purge gas supply system 64 has a gas passage 78 connected to the gas inlet 56. The gas passage 78 is sequentially provided with an on-off valve 80 and a flow rate controller 82 such as a mass flow controller so that a purge gas is allowed to flow intermittently while controlling the flow rate as will be described later. Here, for example, a rare gas Ar is used as the purge gas. As the purge gas, other rare gas such as He or N ₂ gas which is an inert gas may be used.

  Each gas as described above is allowed to flow from the gas injection holes 54 to the processing space S between the gas injection plate 52 and the mounting table 22 while being diffused in the gas diffusion chamber 48 in the peripheral direction. A distance H1 between the gas injection plate 52 and the upper surface (wafer mounting surface) of the mounting table 22 is made as small as possible in order to facilitate gas switching in the processing space S, and is set to about 10 mm, for example. ing.

  Here, the example of arrangement | positioning of the said gas injection hole 54 in the shower head apparatus 46 which is the characteristics of this invention is demonstrated in detail. As shown also in FIG. 2, the diameter D1 of the gas injection plate 52 is set to a value larger than the diameter of the semiconductor wafer W, for example, about 360 mm, and the diameter D2 of the circular region 83 in which the gas injection holes 54 are formed. Also, a value larger than the diameter of the semiconductor wafer W, for example, about 310 mm is set.

  The plurality of gas injection holes 54 are arranged along a plurality of spiral curves 84 virtually formed around the center of the gas injection plate 52. In FIG. 2, the virtual spiral curve 84 is partially visualized for easy understanding of the present invention. The opening area of each gas injection hole 54 formed along the spiral curve 84 is gradually reduced from the periphery of the gas injection plate 52 toward the center.

  In this case, the opening area of the gas injection hole 54 may be slightly smaller as it goes to the center of the gas injection plate 52, or a plurality of, for example, two to three adjacent to each other. The opening area of the gas injection holes 54 may be set to be the same, and may be gradually reduced as they go to the center by two to three. In any case, the opening area of the gas injection holes 54 that are adjacent to each other in a plan view is set to be gradually reduced toward the center so as not to be connected.

  In the illustrated example, each gas injection hole 54 has a circular shape. In FIG. 2, the arrangement of the gas injection holes 54 is formed using any three numerical values adjacent to each other in the Fibonacci sequence. Here, the Fibonacci number sequence is a number sequence as shown below, and any term (numerical value) is a number sequence that is the sum of the two preceding terms.

  0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, ...

  This Fibonacci sequence appears in many natural phenomena, for example in the arrangement of sunflower seeds. Here, three adjacent numerical values of the Fibonacci sequence, for example, “13, 21, 34” are selected and used.

  Specifically, among the plurality of spiral curves 84, the total number of spiral curves 84A heading in the clockwise direction 90 from the peripheral portion to the central portion of the gas injection plate 52 is the above three when counted. It is set to be “34” which is the maximum value among the selected numerical values. Then, on one spiral curve 84A in the clockwise direction 90, the gas injection holes 54 are set to be “13” which is the minimum value among the three selected numerical values. Yes. Accordingly, the number of gas injection holes 54 arranged in the gas injection plate 52 is “442” (= 34 × 13).

  As described above, the opening area of the gas injection hole 54 arranged on the spiral curve 84A, that is, the diameter here is made smaller from the peripheral part to the center part of the gas injection plate 52, Adjacent holes do not communicate with each other. A central gas injection hole 94 different from each gas injection hole 54 is formed at the center of the gas injection plate 52 so as to improve the in-plane uniformity of the film thickness at the center of the wafer W. It has become.

  Here, of the plurality of spiral curves 84, the total number of spiral curves 84B heading in the counterclockwise direction 92 from the peripheral portion to the central portion of the gas injection plate 52 is the above three when counted. It is set to be “21” which is an intermediate value among the selected numerical values. That is, one gas injection hole 54 is positioned on the two spiral curves 84A and 84B.

  The diameter of each gas injection hole 54 is set to be equal to or larger than the interval between the gas injection hole 54 and the adjacent gas injection hole 54. Specifically, in FIG. 2, when attention is paid to a specific gas injection hole 54A, the diameter of the gas injection hole 54A is set to X1, and a spiral shape directed in the clockwise direction 90 with respect to the gas injection hole 54A. The intervals between the gas injection holes 54 adjacent to each other on the curve 84A are Xa and Xb, respectively, and both are adjacent to each other on the spiral curve 84B directed in the counterclockwise direction 92 with respect to the gas injection holes 54A. If the intervals between the gas injection holes 54 are Xc and Xd, respectively, the intervals Xa to Xd are set to dimensions that have a diameter X1 or less. Therefore, in practice, the diameter of the gas injection hole 54 is larger than shown. As shown in the figure, the “intervals Xa to Xd” are the shortest distances between the peripheral edges of the two adjacent gas injection holes 54.

  That is, by setting the dimensions as described above, each gas injection hole 54 is adjacent to the adjacent gas injection holes 54 so as not to be excessively wide. The in-plane uniformity of the film thickness is improved by preventing the area between the gas injection holes 54 from becoming too wide.

  Further, the intervals Xa to Xd between the gas injection holes 54 adjacent on the same spiral curve 84 are not more than the interval H1 (see FIG. 1) between the gas injection plate 52 and the mounting table 22, preferably The wafer W is set to have a size of 0.9 times or less of the interval H1, and the gas injected from the plurality of gas injection holes 54 is sufficiently diffused in the processing space S until reaching the wafer W. The occurrence of gas concentration is prevented from occurring above, and the in-plane uniformity of the film thickness is improved. According to the arrangement rule of the gas injection holes 54 described later, the distance between the centers of adjacent gas injection holes 54 on one spiral curve 84 (84A, 84B) increases toward the outer side, but the outer gas injection Also in the hole 54, the outer gas injection hole 54 has a larger diameter so that the relationship between the interval H1 and the intervals Xa to Xd is established.

  As shown in FIG. 3, the central gas injection hole 94 is provided so as to penetrate the screw member 96 in the vertical direction. The screw member 96 is detachably attached to the central portion of the gas injection plate 52 with a screw. It has become. In this case, since the screw member 96 having a different inner diameter of the center gas injection hole 94 can be replaced, the optimum center gas injection hole 94 can be selected as necessary. The inner diameter of the central gas injection hole 94 is about 1.0 to 1.3 mm. If the inner diameter is smaller than 1.0 mm, the flow rate of the gas is too small and the central gas injection hole 94 is provided. If the effect is lost and the thickness is larger than 1.3 mm, the gas flows excessively and adversely affects the in-plane uniformity of the film thickness. Here, the inner diameter of the central gas injection hole 94 is set to about 1.2 mm.

  Here, the geometric feature of the arrangement of the gas injection holes 54 using the Fibonacci sequence will be described in detail with reference to FIG. FIG. 4 is a diagram illustrating only the gas injection holes 54 in FIG. First, of the plurality of gas injection holes 54, the gas injection hole 54 to be positioned at a specific reference position S0 on the outermost periphery is defined as a reference gas injection hole 54A. This reference gas injection hole 54 </ b> A is located farthest from the center position of the gas injection plate 52 among all the gas injection holes 54.

  Then, starting from the reference gas injection hole 54A, it rotates sequentially in one of the clockwise direction and the counterclockwise direction, here the counterclockwise direction 92, by the rotation angle corresponding to the golden angle or its approximate value. In addition, for each rotation, the length of 1 / [number of helical curves] of the pitch P1 in the radial direction of the gas injection plate 52 (see FIG. 4) of the gas injection holes adjacent to each other on one helical curve. The whole is formed so that new gas injection holes are sequentially arranged at positions shifted inward in the radial direction. Then, by connecting all the gas injection holes 54 in a curved shape in the radial direction, the spiral curve is virtually formed. Here, the pitch P1 refers to the distance from the center of the gas injection plate 52 to the center of each gas injection hole 54 in the two adjacent gas injection holes 54 on one spiral curve 84 (84A, 84B). It means the difference in distance.

Specifically, the golden ratio is “1: (1 + √5) / 2”, and the golden angle is defined as a central angle corresponding to a short arc when the circumference is divided by the golden ratio. Is required.
360 degrees × 1 / [1+ (1 + √5) / 2] = 137.57077
The above rotation angle does not have to be strictly a golden angle, and an approximate value of the golden angle, for example, an angle in the range of 136 to 138 degrees can be used. The rotation angle is set to an angle that is not divisible by 360 degrees.

  Here, 137.5 degrees is used as the rotation angle, the reference position S0 is set as a starting point (reference), the rotation is performed 137.5 in the counterclockwise direction 92, and the gas injection holes adjacent to each other on the curve each time the rotation is performed. It is set so that the gas injection holes are arranged at positions shifted in the central direction of the gas injection plate by a length of “1/34” (34: the number of spiral curves) of the pitch in the gas injection plate central direction. ing. The arrangement of the gas injection holes 54 as described above is a 34/13 square (also a 34/21 square) when expressed in a fractional polygon.

In FIG. 4, the pitch P1 of the gas injection holes adjacent to each other on the spiral curve of 1 in the center direction of the gas injection plate is set to 11.5 mm, and accordingly, 137 from the reference position S0 counterclockwise. Each time it rotates by 5 degrees, it is displaced by 0.33 mm (= 11.5 mm / 34) toward the center of the gas injection plate.
Therefore, the position of each gas injection hole can be expressed as follows using a polar coordinate system.
(Rn, θn) = (r0−0.33n, θ0 + 137.5n)
However, (r0, θ0) is the polar coordinate of the reference position S0, n is the number of rotations, and the rotation angle is the positive direction in the counterclockwise direction.
In FIG. 4, the position after the first rotation is represented as position S1, the position after the second rotation is represented as position S2, and the position after the third rotation is represented as position S3. When the rotation is repeated and the 34th time (the same number as the number of spiral curves 84A) is reached, the position after the rotation is represented as a position S34. Here, the reference position S0 and the position S34 are positions of the adjacent gas injection holes 54 on the same spiral curve 84A (see FIG. 2). At this time, an angle θ formed by the reference position S0 and the position S34 with respect to the center of the gas injection plate is “5 degrees”.

Here, the above “5 degrees” is obtained as follows.
137.5 degrees × 34 (number of spiral curves) = 4675 degrees 4675 degrees− (360 degrees × 12) = − 355 degrees 355 degrees−360 degrees = −5 degrees That is, in one spiral curve 84A The angular position of the gas injection hole 54 adjacent to the gas injection hole 54A at the reference position S0 is an angle position that is returned clockwise by “5 degrees” from the reference position S0. In the present embodiment, the total number of gas injection holes 54 determined by the above operation is 442.
Further, as described above, the pitch in the radial direction of the gas injection plate 52 of the gas injection holes 54 adjacent to each other in one spiral curve 84A is P1 (here, 11.5 mm).
Accordingly, the position of each gas injection hole 54 in one spiral curve 84A can be expressed as follows using a polar coordinate system.
(Rm, θm) = (ra-11.5 (m−1), θa-5 (m−1))
However, “(ra, θa)” means the polar coordinates of the outermost gas injection hole 54 located on the spiral curve 84A, and “m” means the number of the gas injection hole 54 from the outside. In addition, the rotation angle is positive in the counterclockwise direction.

As described above, the rotation angle is not limited to the golden angle of 137.5 degrees, and even if it is slightly shifted, there is little adverse effect on the in-plane uniformity of the film thickness, and the range is an approximate value of the golden angle. An angle within a certain range of 136 to 138 degrees can also be used. However, the rotation angle is a numerical value that cannot be divided by 360 degrees. When 360 degrees is divisible by this value, the arrangement of the gas injection holes 54 is regularly arranged radially from the center of the gas injection plate 52 along a plurality of directions, and is distributed in the circumferential direction. As a result, there is a fear that the gas concentration in the surface is biased. Here, the diameter of the outermost gas injection hole is set to 10 mm, the diameter of the innermost gas injection hole is set to 2 mm, and the diameter of the gas injection hole is the same spiral curve from the outer periphery. As it goes to the center side, it is reduced by about 0.5 mm.
Thus, the gas injection hole 54 of this embodiment is considerably larger in size than the gas injection hole of the gas injection plate of a normal shower head. Thereby, conductance can be improved and gas can be introduced and replaced quickly. However, if the size (diameter) of the gas injection hole is excessively increased, the gas concentration is increased only around the gas injection hole, and the uniformity is deteriorated. In the present embodiment, the gas injection hole with the largest possible diameter is increased to improve conductance, while the gas injection holes are arranged based on the Fibonacci number sequence to maintain the uniformity of the gas concentration. .

  The operation of the entire film forming apparatus formed as described above is controlled by the apparatus control unit 100 including, for example, a computer. A computer program for performing this operation is stored in the storage medium 102. Yes. The storage medium 102 includes, for example, a flexible disk, a CD (Compact Disc), a hard disk, a flash memory, or a DVD. Specifically, in response to a command from the apparatus control unit 100, supply of each gas is started, stopped, flow rate is controlled, process temperature and process pressure are controlled, and the like.

<Film formation method>
Next, a film forming method performed using the film forming apparatus configured as described above will be described with reference to FIG. FIG. 5 is a timing chart showing an example of the supply timing of each gas. Here, as an example of the film forming method, an ALD method in which each gas is intermittently supplied alternately to deposit thin films will be described.

  First, when the wafer W is loaded into the evacuated processing container 4 and placed on the mounting table 22, the inside of the processing container 4 is sealed. Then, the heating means 24 provided on the mounting table 22 raises the wafer W to a predetermined process temperature and maintains this temperature. At the same time, the respective gases are introduced into the processing space S from the gas injection holes 54 of the gas injection plate 52 of the shower head device 46 provided on the ceiling portion of the processing container 4 in the order shown in FIG.

  In this case, the TEMAHf gas, which is a raw material gas, is supplied into the gas diffusion chamber 48 of the shower head main body 50 by the raw material gas supply system 60, and the water vapor, which is a reactive gas (oxidizing gas), is supplied by the reactive gas supply system 62. The Ar gas, which is a purge gas, is supplied into the gas diffusion chamber 48 of the shower head body 50 by the purge gas supply system 64. Each gas flows from the respective gas injection holes 54 toward the lower processing space S while diffusing horizontally into the gas diffusion chamber 48. The start and stop of the supply of each gas are performed by opening and closing the corresponding on-off valves 68, 74, and 80.

  An example of the timing of supplying each gas is shown in FIG. 5, and the raw material gas TEMAHf (FIG. 2 (A)) and the reaction gas water vapor (FIG. 2 (B)) are alternately and intermittently. Repeated supply is used as a pulsed supply mode. Then, Ar gas, which is a purge gas, is allowed to flow during a period in which the supply gas supply suspension period and the reaction gas supply suspension period overlap, thereby facilitating the discharge of the residual gas in the processing container 4. When the source gas is supplied, the TEMAHf gas is adsorbed on the surface of the wafer W, and when the reaction gas is supplied, the TEMAHf gas adsorbed on the wafer W reacts with water vapor as a reaction gas and is oxidized to form thin atoms. A hafnium oxide having a thickness of a level or a molecular level is formed. By repeating this operation, the thin films are laminated, and a hafnium oxide film having a desired thickness is obtained by repeating the necessary number of times (cycles).

  Here, one cycle is from the start of the source gas supply period to the start of the next source gas supply period. As an example, the supply period T1 of the source gas is about 0.1 to 5.0 seconds, the supply period T2 of the reaction gas is about 0.1 to 5.0 seconds, and the purge period T3 is 0.1 ˜10.0 seconds. Moreover, as an example of the supply amount of each gas, TEMAHf gas is about 1 to 500 mg / min, water vapor is about 1 to 500 mg / min, and Ar gas is about 100 to 5000 sccm. The process pressure is in the range of 1 to 10 Torr, and is set in the range of 1 to 3 Torr here. Moreover, process temperature is about 200-500 degreeC. In addition, the supply mode of each gas by the ALD method shown in FIG. 2 is merely an example, and is not limited to this.

  Here, in the shower head device 46 of the present invention, each gas injection hole 54 is arranged along a plurality of spiral curves 84 virtually formed around the center of the gas injection plate 52. Each gas can be supplied while being uniformly dispersed in the plane direction toward the processing space S located below. Therefore, the in-plane uniformity of the thin film formed on the surface of the semiconductor wafer W can be improved.

  In particular, in the present embodiment, the maximum value of any three adjacent numerical values in the Fibonacci sequence is a spiral curve 84A directed in the clockwise direction 90 from the peripheral portion of the gas injection plate 52 to the central portion, for example. Since the number of gas injection holes 54 corresponding to the minimum value of the above three values is arranged on the curve 84A, the number of gas injection holes 54 is formed on the surface of the semiconductor wafer W. The in-plane uniformity of the thin film can be further improved.

  In the example shown in FIGS. 2 and 3, “34” is obtained when the number of spiral curves is counted in the clockwise direction 90, and “21” is obtained when counted in the counterclockwise direction 92. However, the two may be set in opposite directions.

<Evaluation of the present invention>
Next, as described above, a thin film is actually formed on the surface of the semiconductor wafer by using the film forming apparatus having the shower head device according to the present invention using the three numerical values “13, 21, 34” in the Fibonacci sequence. Since the experiment to deposit was conducted, the evaluation result will be described. A hafnium oxide film was formed using TEMAHf gas as a source gas and water vapor as a reaction gas. Here, the flow rate of TEMAHf is 100 mg / min, the flow rate of water vapor is 40 mg / min, and the number of film formation cycles is 12. The inner diameter of the central gas injection hole 94 was set to 1.2 mm, the process pressure was set to 80 Pa, and the process temperature was set to 350 ° C.

  As a comparative example, a film forming apparatus provided with a shower head having slit-like gas injection holes as disclosed in Patent Document 3 was used. A central gas injection hole having an inner diameter of 1.3 mm is formed at the center of the shower head. Other process conditions were set to be the same as in the case of using the showerhead device of the present invention.

  As a result, when the conventional shower head was used, the in-plane uniformity of the film thickness was 1.04% when the average film thickness was 34.3 mm. When the apparatus was used, the in-plane uniformity of the film thickness was 0.98% when the average film thickness was 36.1 mm. Thus, when the shower head apparatus of this invention was used, it has confirmed that the in-plane uniformity of a film thickness could be improved.

<Modified Example>
Next, a modified embodiment of the shower head device of the present invention will be described. Here, an Archimedean spiral and a logarithmic spiral are used as a spiral curve for arranging the gas injection holes. FIG. 6 is a diagram showing a spiral mode used in a modified embodiment of the showerhead device, FIG. 6 (A) shows an example of a logarithmic spiral used in the first modified embodiment, and FIG. 6 (B) is a second modified embodiment. An example of the Archimedes spiral used for an example is shown.

Here, the Archimedean spiral is a curve represented by the following polar coordinate formula.
r = aθ
r: distance from the origin, a: constant, θ: rotation angle The logarithmic spiral is a curve represented by the following formula in polar coordinate display (r, θ).
log (r) = bθ · log (ae)
r: distance from the origin, e: Napier number, a, b: fixed constant, θ: rotation angle In this case, the above spiral one curve (either Archimedes spiral or logarithmic spiral) is expressed as a golden angle or A plurality of spiral curves for arranging the gas injection holes are defined by sequentially rotating in either the clockwise direction or the counterclockwise direction by an angle corresponding to the approximate value. become. This point is similar to the case shown in FIGS.

  In this case, the number of the plurality of spiral curves formed as a whole is set so as to be the maximum value of any three adjacent numerical values in the Fibonacci sequence. Then, on one spiral curve, the number of gas injection holes is set to any one of the other two numerical values among the above three numerical values.

  Specifically, as described above, when “13, 21, 34” is selected as any three adjacent numerical values in the Fibonacci sequence, the number of spiral curves is set to “34”. For all spiral curves, “13” gas injection holes or “21” gas injection holes may be arranged on one spiral curve. Good.

  In this case, for example, when 34 spiral curves are formed, they may intersect each other. However, when gas injection holes are arranged at the intersection, the gas injection holes intersect with two spiral curves. It will be arranged so that it exists in common above. As in the previous embodiment, the opening area of the gas injection hole is gradually reduced from the peripheral part of the gas injection plate toward the central part.

  The rotation angle of the spiral curve is a numerical value that is in the range of 136 to 138 degrees and cannot be divided by 360 degrees, as in the case described with reference to FIGS. In the case of the first and second embodiments, the same operational effects as those of the embodiment described above with reference to FIG. 2 and the like can be exhibited.

  In each of the above-described embodiments, the case where “13, 21, 34” is selected as an arbitrary three number from the Fibonacci sequence is described as an example, but the present invention is not limited to this, and the diameter of the gas injection plate is considered. In this case, practically, any three adjacent numbers are preferably selected from “8, 13, 21, 34, 55, 89, 144”.

  Further, in each of the above embodiments, the gas injection hole has been described as an example in which the shape is circular. However, the present invention is not limited to this, and the shape of the gas injection hole is set to a triangle, a quadrangle, an ellipse, or the like. May be. In each of the above embodiments, the case where TEMAHf, which is an organic metal material, is used as a raw material during film formation has been described as an example. However, the present invention is not limited to this, and other organic metal materials such as TEMAZr, La (amd) ) Or the like may be used. Furthermore, the material is not limited to the organometallic material, and other film forming materials may be used.

Furthermore, in each of the above-described embodiments, water vapor, which is an oxidizing gas, is used as the reactive gas. However, other oxidizing gases such as O ₂ and O ₃ may be used, or a film should be formed as the reactive gas. Depending on the film type, a reducing gas such as H ₂ , SiH ₄ , or an organic acid, or a nitriding gas such as NH ₃ may be used.

  Although the semiconductor wafer is described as an example of the object to be processed here, the semiconductor wafer includes a silicon substrate and a compound semiconductor substrate such as GaAs, SiC, GaN, and the like, and is not limited to these substrates. The present invention can also be applied to glass substrates, ceramic substrates, and the like used in display devices.

DESCRIPTION OF SYMBOLS 2 Film-forming apparatus 4 Processing container 10 Vacuum exhaust system 18 Holding means 22 Mounting stand 46 Shower head apparatus 48 Gas diffusion chamber 50 Shower head main body 52 Gas injection plate 54 Gas injection hole 60 Raw material gas supply system 62 Reaction gas supply system 64 Purge gas supply System 84 Helical curve 84A Clockwise curve 84B Counterclockwise curve 94 Center gas injection hole 96 Screw member W Semiconductor wafer (object to be processed)

Claims (17)

In a shower head device for introducing gas into a processing container containing a target object on which a thin film is formed,
A shower head body in which a gas diffusion chamber for diffusing the gas is formed;
A plurality of gas injection holes provided in the gas injection plate of the shower head body,
The shower head device, wherein the plurality of gas injection holes are arranged along a plurality of spiral curves virtually formed around a center portion of the gas injection plate. 2. The shower head device according to claim 1, wherein an opening area of the gas injection hole is gradually reduced from the peripheral part toward the central part. The spiral curve in which the maximum value of any three adjacent numerical values in the Fibonacci sequence is directed in the clockwise direction or the counterclockwise direction from the peripheral portion to the central portion of the gas injection plate is counted. 3. The shower head device according to claim 1, wherein the shower head device is set to be a numerical value of hour. 4. The shower head according to claim 3, wherein the gas injection holes of the minimum value among the three numerical values are arranged on a spiral curve in a direction in which the maximum value is counted. apparatus. The plurality of spiral curves have only a rotation angle corresponding to a golden angle or an approximate value approximating this starting from a gas injection hole located at a specific reference position on the outermost periphery of the plurality of gas injection holes. The pitch is sequentially rotated in either the clockwise direction or the counterclockwise direction, and the pitch in the radial direction of the gas injection plate of the gas injection holes adjacent to each other on one spiral curve is rotated at each rotation. It is virtually formed by sequentially arranging new gas injection holes at positions shifted inward in the radial direction by the length of 1 / [number of spiral curves] and connecting the gas injection holes in the radial direction. The showerhead device according to any one of claims 1 to 4, wherein the showerhead device is provided. 6. The shower head device according to claim 5, wherein the rotation angle is a value that is in a range of 136 to 138 degrees and is not divisible by 360 degrees. The showerhead device according to claim 1 or 2, wherein the spiral curve is an Archimedean spiral. The showerhead device according to claim 1 or 2, wherein the spiral curve is a logarithmic spiral. The plurality of spiral curves are sequentially rotated in one of a clockwise direction and a counterclockwise direction by a rotation angle corresponding to a golden angle or an approximate value approximate to the one spiral curve. 9. The shower head device according to claim 7, wherein the shower head device is formed virtually by rotating. The number of the plurality of spiral curves is the maximum value of any three adjacent numerical values in the Fibonacci sequence, and the gas injection hole has the number 3 on the one spiral curve. The showerhead device according to any one of claims 7 to 9, wherein only one of the other two numerical values is arranged. The plurality of spiral curves have only a rotation angle corresponding to a golden angle or an approximate value approximating this starting from a gas injection hole located at a specific reference position on the outermost periphery of the plurality of gas injection holes. The pitch is sequentially rotated in either the clockwise direction or the counterclockwise direction, and the pitch in the radial direction of the gas injection plate of the gas injection holes adjacent to each other on one spiral curve is rotated at each rotation. It is virtually formed by sequentially arranging new gas injection holes at positions shifted inward in the radial direction by the length of 1 / [number of spiral curves] and connecting the gas injection holes in the radial direction. The shower head device according to claim 7, wherein the shower head device is provided. The shower head device according to claim 9 or 11, wherein the rotation angle is a value that is in a range of 136 to 138 degrees and is not divisible by 360 degrees. The distance between the shortest peripheral edges of adjacent gas injection holes on the same spiral curve is set to a size equal to or smaller than the diameter of the gas injection holes. The showerhead device according to item. The distance between the shortest peripheral edges of the adjacent gas injection holes on the same spiral curve is the gas injection plate and the holding surface of the holding means installed to hold the object to be processed in the processing container. The shower head device according to any one of claims 1 to 13, wherein the shower head device is set to be equal to or smaller than an interval between the two. The center gas injection hole different from the plurality of gas injection holes formed along the plurality of spiral curves is formed at the center of the gas injection plate. The showerhead device according to any one of the above. The shower head device according to claim 15, wherein a screw member in which the central gas injection hole is formed is attached to a central portion of the gas injection plate. In a film forming apparatus for forming a thin film on an object to be processed,
A processing container for containing the object to be processed;
Holding means for holding the object to be processed;
Heating means for heating the object to be processed;
The shower head device according to any one of claims 1 to 16,
An evacuation system for evacuating the atmosphere in the processing vessel;
An apparatus controller for controlling the operation of the entire film forming apparatus;
A film forming apparatus comprising:

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