JPH0826898A - Method for making artificial lattice - Google Patents

Abstract

PURPOSE:To accurately control the thicknesses of the respective layers constituting an artificial lattice by combining respective steps, i.e., moving a substrate at a constant speed, charging electric power to targets, and opening/closing 1st and 2nd shutters, so as to make a specific action. CONSTITUTION:The pressure of a nitrogen gas is set at 1Pa and a substrate holder 10 is revolved at 2rpm. A 1st target 12 consisting of vanadium is charged with an electric power of 185W and a 2nd target 14 consisting of carbon with an electric power of 240W. When a standard substrate 2a comes to this side of the 1st target 12, a 1st shutter 16 is opened, and this shutter is closed after making four revolutions. As a result, vanadium nitride is accumulated in thickness of 2.5nm on each of six substrates. Subsequently, the standard substrate 2a comes to this side of the 2nd target 14, the 2nd shutter 18 is opened, and this shutter is closed after making one revolution. As a result, carbon nitride is accumulated in thickness of 2.5nm on the above vanadium nitride, thus completing a process equivalent to one cycle. The above operation is repeated 30 cycles.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to a method of making artificial lattices on a substrate by sputtering a plurality of targets.

[0002]

2. Description of the Related Art Two kinds of substances (first layer substance and second layer substance) are respectively set to thicknesses λ1 and λ2, and a total Λ (= λ
A multilayer film deposited for N periods with a period length of 1 + λ2) is called an artificial lattice or a superlattice. Examples of the substance forming each layer include a single element, an alloy, and a compound (nitride, oxide, semiconductor, etc.). Since artificial lattices are substances that do not exist in nature, they can be expected to have special functions. Recently, as the materials constituting the artificial lattice, the scope of research has expanded to metals other than compound semiconductors, carbides, nitrides, and oxides. Also, from the viewpoint of application, these artificial lattices have many possibilities such as an X-ray microscope, a monochromator, an IC mask, a superconducting element, a magnetoresistive element, and a next-generation magneto-optical disk, in addition to the super-high frequency semiconductor element. is there.

Various methods such as a sputtering method, a laser ablation method, and an ion beam sputtering method have been tried as a method for producing an artificial lattice. Among these manufacturing methods, the sputtering method is drawing attention from the viewpoint of mass production.

Ishii et al. Is a sputtering method using two targets (Mo and Si) and has a period length of 6.7 nm, “M”.
The “o / Si” artificial lattice was produced and the soft X-ray has a reflectance of 46%. This artificial lattice has a reflection characteristic that can be used as an optical mirror or mask for reduction exposure used under conditions close to direct incidence. (SR Science and Technology Info
rmation, Vol.1, No.1, 1991)

Yamamoto et al. Also produced an artificial lattice of 161 periods of "Mo / Si" by a sputtering method using two targets (Mo and Si) and obtained a high reflectance of 60 to 80%. .

[0006]

The important points in producing an artificial lattice are (1) the film thickness of the first layer and the second layer is
It should be constant over N cycles, and there should be no irregularities on the interface. (2) From the viewpoint of mass production, it is possible to manufacture a large number of artificial lattices at one time. These points will be described in detail below.

(1) The thicknesses of the first layer and the second layer are constant over N cycles and there is no unevenness on the interface. Particularly in the optical artificial lattice, if there is an error in the film thickness or unevenness of the interface, the disorder is accumulated as the number of laminations increases, and the reflectance decreases. Assuming that the uncertainty of the position of the interface due to such turbulence is Δz, the attenuation factor of the reflectance is exp (−4π ² Δz ² / Λ when the artificial period is Λ.
² ) For example, the film thickness of each layer is 2 nm (Λ =
4 nm), to obtain an attenuation factor of 80%, Δ
z needs to be 0.2 nm. As described above, in the process of manufacturing the artificial lattice, it is necessary to make the uncertainty of the position of the interface as small as possible.

In the conventional process for producing an artificial lattice by the sputtering method, the target for depositing the first layer and the target for depositing the second layer are discharged at the same time, the shutters are simultaneously opened, and the targets are sequentially opposed to each other. By rotating the substrate, the first layer and the second layer are alternately laminated on the substrate. This method has the following problems. The deposition rate of each film first depends on the power applied to each target. In addition, the film thickness deposited when the substrate passes the facing position of the target also depends on the substrate rotation speed. Therefore, in order to deposit a predetermined film thickness during one rotation of the substrate, it is necessary to adjust the input power and the substrate rotation speed, and the input power and the substrate rotation speed are independently set to arbitrary values. You cannot do it. Also,
In the sputtering method, it is known that the film quality changes considerably depending on the input power. Furthermore, it is also possible that the roughness of the interface in the artificial lattice changes depending on the deposition rate. Therefore, the optimum conditions of input power are considerably limited. On the other hand, the fluctuation of the substrate rotation speed causes a film thickness error, but the substrate rotation mechanism may also have an optimum speed condition in which the fluctuation of the rotation speed hardly occurs. That is, even if the input power and the substrate rotation speed are adjusted so that a predetermined film thickness can be deposited during one rotation of the substrate,
There is a problem that the input power and the substrate rotation speed are not necessarily the optimum conditions for producing a high-quality artificial lattice with less film thickness error and interface irregularities.

Particularly, in the optical artificial lattice, the first layer and the second layer are used.
Since high reflectance can be obtained when the film thicknesses of the layers are almost equal, the condition that the film thicknesses of the first layer and the second layer are made equal is further added, and the constraint on the process parameter becomes larger. For example, when an artificial lattice is made of a combination of two kinds of materials with greatly different sputter rates (for example, heavy metal and carbon), if the first layer and the second layer are to be deposited in the same film thickness while the substrate makes one rotation, It is necessary to make the input power of the target with the higher sputtering rate extremely lower than that of the target with the lower sputtering rate. By doing so, the discharge tends to be unstable in the target whose input power is extremely low, and the reproducibility of the film thickness and the film quality cannot be obtained in the deposited layer.

Recently, artificial lattices made of nitrides, carbides, oxides, etc. have been studied in order to improve the smoothness of the interface. However, these artificial lattices use the reactive sputtering method. The constraint on the optimum condition of the target input power becomes even larger.

(2) Regarding the fact that a large number of artificial lattices can be manufactured at once from the viewpoint of mass production. The above-mentioned literature on the sputtering method only describes data for research and trial production, and does not touch on the problem in actual mass production. In the prior art, while rotating the substrate so as to face each target in order, two targets are simultaneously discharged and the shutter is opened at the same time. In this state, an artificial lattice is produced on the substrate. . It is necessary to alternately stack the first layer and the second layer on the substrate, but if the shutters are opened at the same time, the relative positional relationship between the substrate and each target becomes a problem, and it can be attached to the substrate holder. Since the number of substrates is reduced, it is difficult to manufacture a large number of artificial lattices at once. This point will be described with reference to the drawings.

FIG. 11 (A) shows a conventional rotary substrate holder 10 in which six substrates 2a to 2f are mounted on a cylindrical surface and an artificial lattice is produced using two targets 12 and 14. FIG. 6 is a plan view of the method. Two targets 1
2 and 14 are discharged at the same time, and two shutters 16,
When 18 is opened at the same time, the first layer by the target 12 and the second layer by the target 14 are deposited on each of the six substrates while the substrate holder 10 makes one rotation. The artificial lattice is completed. By the way, at the substrate position shown in this drawing, the two shutters 12, 1
When 4 are opened simultaneously, the substrate 2a first faces the target 12 and starts deposition from the first layer, whereas the substrate 2d first faces the target 14 and deposits from the second layer. Will start. Eventually, the three substrates 2a-2c will start to deposit from the first layer material on the substrate and the three substrates 2d to 2f will start to deposit the second layer material. That is, the artificial lattices are not exactly the same. And the first layer material and the second layer
The quality of the artificial lattice may differ depending on which of the layer materials contacts the substrate. For example, the degree of mutual diffusion may be different, or the adhesion between the substrate and the film may be different, depending on the compatibility between the film that contacts the substrate and the substrate. As described above, when there is a requirement that a specific one of the two layers must be in contact with the substrate, the substrate arrangement as shown in FIG. 11A does not work. Similarly, when there is a requirement to terminate the top layer (surface layer) of the artificial lattice with a specific layer, the method of closing the two shutters at the same time also fails.

On the other hand, as shown in FIG.
If only three substrates 2a to 2c are used, even if the two shutters 16 and 18 are opened and closed at the same time, all the substrates will be the first
The arrangement of the layers and the second layer can be exactly the same. However, the number of processed substrates must be reduced.

Therefore, an object of the present invention is to provide a method capable of precisely controlling the film thickness of each layer constituting the artificial lattice and producing a large amount of artificial lattice thin film at one time.

[0015]

The method for producing an artificial lattice according to the present invention is characterized by mainly controlling the opening / closing of the shutter. That is, the present invention is a method of producing an artificial lattice in which two kinds of deposited layers are periodically repeated on a substrate by sputtering a plurality of targets. First, the substrate circulates while facing the plurality of targets in order. The substrate is moved at a constant speed so that the first layer deposition target (hereinafter referred to as the first shutter) and the second layer deposition target shutter (hereinafter referred to as the first shutter). 2 shutters) and a predetermined power are applied to the first layer deposition target and the second layer deposition target, respectively. Then, in such a state, the following shutter opening / closing control is performed. First, the first shutter is opened when the substrate is not in the facing position of the first layer deposition target, and the first shutter is closed after the substrate has passed the facing position of the first layer deposition target a predetermined number of times.
As a result, the first layer is deposited on the substrate to a predetermined thickness. Next, the second shutter is opened when the substrate is not in the facing position of the second layer deposition target, and the second shutter is closed after the substrate has passed the facing position of the second layer deposition target a predetermined number of times. As a result, the second layer is deposited on the first layer by a predetermined thickness. This completes the artificial lattice for one cycle. Next, by repeating such shutter opening / closing control N times, an artificial lattice of N cycles is completed.

The first layer deposition target is not limited to one, but may be two or more. That is, the deposition rate may be increased by using two targets of the same type,
It is also conceivable to use different types of targets to form the composite material layer on the substrate. Similarly, the second layer deposition target is not limited to one.

In the fabrication of the artificial lattice, the first layer and the second layer
Since it is necessary to repeat the cycle consisting of layers for N cycles,
The substrate needs to circulate and move while sequentially facing a plurality of targets. This circulatory movement can typically be realized by a rotational movement of the substrate. For example, a substrate is attached to a cylindrical or circular flat plate type substrate holder, and the substrate holder is rotated.

The opening / closing timing of the shutter must be set at a time when the substrate is not facing the target. The period in which the film is deposited on the substrate is a period from when a part of the substrate starts to face the target to when the substrate is completely removed from the target facing position. Therefore, the shutter is opened at a timing before a part of the substrate starts facing the target. If the shutter is opened after a part of the substrate starts to face the target, the deposited layer that has started to be deposited at that time becomes smaller than the target deposited film thickness. The shutter closing timing is also after the substrate has completely passed the target facing position.

The elapsed time until the substrate returns to the original position is
Hereinafter, when it is called a circulation required time, in the case of a rotary type substrate holder, the circulation required time is 1
It corresponds to the time to rotate. Hereinafter, the rotating substrate holder will be described as an example. During one rotation of the substrate holder, the substrate passes through the facing position of the first layer target only once, during which the first layer is deposited by a predetermined film thickness. If the deposited film thickness is equal to the required film thickness of the first layer, the substrate holder may be rotated once and then the step of depositing the second layer may be performed. If the first layer deposition film thickness during one rotation is smaller than the first layer required film thickness, it is necessary to rotate the substrate holder two or more times and continue the first layer deposition step until the required film thickness is reached. . As can be seen from this description, the film thickness deposited during one rotation of the substrate holder is an integral fraction of the required film thickness of each layer.
(Including the case where the film thickness is equal to the required film thickness). In other words, it is necessary to adjust the substrate rotation speed and the target input power so as to satisfy such conditions. The relationship between the rotation speed of the substrate, the power applied to the target, and the deposited film thickness during one rotation may be known in advance by experiments.

Artificial lattices typically have two layers of N
Although it is manufactured by repeating the cycle only, even when an artificial lattice in which three or more types of layers are repeated by N cycles is manufactured, 2
It can be made in the same way as for the types of layers.

[0021]

The operation will be described by taking the case of using the rotating substrate holder as an example. First, the substrate holder is rotated at a constant speed while a predetermined electric power is applied to all the targets. First, the first shutter is opened to rotate the substrate holder once or twice or more, and then the first shutter is closed to deposit a first layer having a predetermined film thickness on the substrate. Next, the second shutter is opened to rotate the substrate holder once or twice or more, and then the second shutter is closed to deposit a second layer having a predetermined film thickness on the substrate. As a result, the artificial lattice for one cycle is completed. By repeating such a deposition operation of the first layer and the second layer N times, an N-period artificial lattice is completed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a plan layout view showing an embodiment of the present invention and shows a layout relationship between a substrate, a target and a shutter. In this example, an artificial lattice was prepared by depositing one cycle consisting of a vanadium nitride layer having a thickness of 2.5 nm and a carbon nitride layer having a thickness of 2.5 nm for 30 cycles. This artificial lattice is [VN _x (2.5n
m) / CN _x (2.5 nm)] ₃₀ .

In FIG. 1A, six substrates 2a to 2f are mounted on the cylindrical surface of a cylindrical substrate holder 10. The substrate holder 10 rotates around the center line of the cylindrical surface at a rotation speed of 2 rpm. The first target 12 is vanadium and the second target 14 is carbon. By sputtering these targets in a nitrogen gas atmosphere, vanadium nitride and carbon nitride can be deposited on the substrate. First, the pressure of 100% nitrogen gas is kept at 1 Pa, and the first target 12 is
High-frequency power of 5 W is applied to the second target 14 for 24 hours.
Apply 0 W of high frequency power. Two shutters 16,
18 is in the closed state.

When a specific substrate 2a (which will be referred to as a reference substrate) of the six substrates comes to a position before starting to face the first target 12, the first shutter 16 is turned on. open. Then, while the substrate 2a passes through the facing position of the target 12, vanadium nitride is deposited on the substrate 2a with a thickness of 0.625 nm. Similarly, while the next substrate 2b passes the facing position of the target 12, vanadium nitride is similarly deposited on this substrate 2b by the same thickness. In this manner, the six substrates 2a to 2f are provided until the reference substrate 2a returns to the original position shown in FIG. 1A (that is, while the substrate holder 10 makes one rotation).
Vanadium nitride with a thickness of 0.625 nm is deposited on each of the above.

In this state, when the substrate holder 10 is further rotated 3 times (that is, 4 times in total), 0.625 × 4 = 2.5 nm of vanadium nitride is deposited on each of the 6 substrates. This completes the deposition of the first layer. Then, when the substrate holder 10 rotates four times and returns to the substrate position (hereinafter referred to as the A position) shown in FIG. 1A, the first shutter 16 is closed.

Next, the substrate holder 10 is moved from the position A described above.
When is further rotated by a half rotation (180 degrees), the substrate position (hereinafter referred to as B position) shown in FIG. At the position B, the reference substrate 2a is in a position before starting to face the second target 14. Second at this time
Open the shutter 18. While the substrate 2a passes through the position facing the target 14, the substrate 2a contains carbon nitride of 2.5%.
deposited to a thickness of nm. Carbon nitride is deposited on this substrate 2b by the same thickness even while the next substrate 2b passes through the position facing the target 14. In this manner, carbon nitride having a thickness of 2.5 nm is deposited on each of the six substrates 2a to 2f until the reference substrate 2a returns to the B position (that is, while the substrate holder 10 makes one rotation). To do. Then, when the reference substrate 2a returns to the position B, the second shutter 18 is closed. This completes the deposition of the second layer.

When the substrate holder 10 is further rotated a half turn from the position B at the time when the deposition of the second layer is completed, the position of the substrate returns to the position A. With this, the deposition work for one cycle is completed, and one cycle is completed. In the deposition work for one cycle, the number of rotations of the substrate holder is four rotations of the first layer deposition work, half rotation of moving from the A position to the B position, one rotation of the second layer deposition work, and the B position. A total of 6 rotations, which is half a rotation until returning to the A position. The target artificial lattice [VN _x (2.5 nm) / CN _x (2.5 nm)] ₃₀ is completed by repeating the above-described first and second layer deposition operations 30 times.

FIG. 2 is a timing chart in which the above procedure is graphed. The vanadium target shutter (V shutter) is open only while the substrate holder rotates 4 times from position A to position A, and the carbon target shutter (C shutter) is the substrate holder B
It is only open for one full rotation from position to B position. During the first four revolutions of the start, vanadium nitride deposits 2.5 nm. Also, the substrate holder is 4.5
Carbon nitride is deposited by 2.5 nm between the fifth rotation and the fifth rotation. In this way, the substrate holder rotates six times, and thus the work for one cycle (one cycle) is completed. Since this is performed for 30 cycles, the total number of rotations of the substrate holder is 180 rotations. Since the rotation speed of the substrate holder is 2 rpm, the total required time is 90 minutes.

By the way, in FIG. 2, the time axis of the graph of increase in film thickness shows the film thickness of the reference substrate 2a. On the next substrate 2b, as indicated by the broken line 20, the film is deposited with a delay of 1/6 rotation from the reference substrate. In any case, a film is deposited on all six substrates at some point during one rotation of the reference substrate from position A back to position A.

Next, the timing for opening and closing the shutter will be described in detail. In (A) of FIG. 1, in a region L facing the first target 12, many particles sputtered by the target come flying. Therefore, when the substrate position is such that no substrate exists in this region L,
It is necessary to open and close the first shutter 16. If the first shutter 16 is opened or closed while a part of the substrate is included in this region L, vanadium nitride deposited on the substrate while the substrate passes the position facing the first target 16. The film thickness of is less than the planned 0.625 nm. This also applies to the opening / closing timing of the second shutter.

In this embodiment, since the six substrates are mounted on the substrate holder 10 at equal intervals, all the substrates are present at the target facing positions at the A position and the B position regardless of which substrate is the reference substrate. It will be arranged not to.
If the reference substrate is limited to the specific substrate 2a, if the distance between the reference substrate 2a and the substrate 2f in front of it is at least the region L, the other substrate intervals are made smaller than the region L. I don't mind. By doing so, more substrates can be attached to the substrate holder, and mass productivity is improved.

In FIG. 1A, the region L is drawn to be approximately the same as the target size, but in reality, the region L needs to be made larger than the target size to some extent. This is because the sputtered particles fly in directions other than the front of the target. After all, it can be said that the region L at the target facing position is a region in which the amount of particles is large enough to substantially affect the film thickness control.

FIG. 3 is a plan sectional view showing the overall structure of the artificial lattice producing apparatus. This apparatus is provided with a so-called carousel type rotary substrate holder 10, and the positional relationship among the substrate, the target and the shutter is as shown in FIG. 1 described above. In this device, circular targets 12 and 14 each having a diameter of 3 inches are arranged facing each other at positions separated by 180 degrees on the circumference. Each target has a matching circuit 22
And a high frequency power supply 24 are connected. Target 12,
The shutters 16 and 18 are independently provided between the board 14 and the substrate holder 10, and the shutter drive mechanisms 26 and 2 are provided.
It is driven by 8 to open and close. Shutter drive mechanism 2
6, 28 are driven by controlling compressed air of 5 kgf / cm ² .

When the substrate 2 is taken out, the substrate transfer mechanism 3 is used.
By using 0, the substrate 2 can be taken out without exposing the processing chamber, that is, the vacuum container 32 to the atmosphere. The sputtering gas has a structure in which two kinds of gases can be used. For example, argon gas, nitrogen gas, or a mixed gas of both can be used.
The sputtering gas can be supplied to the ring-shaped pipe 34 while controlling the flow rate with a mass flow meter (not shown), and the gas is introduced into the vacuum container 32 from a plurality of gas blowing holes of the ring-shaped pipe 34. .

To manufacture the artificial lattice as described above using this apparatus, first, the inside of the vacuum container 32 is evacuated to a vacuum state of 10 ^-5 Pa or less, and then 100% nitrogen gas is introduced, The pressure in the vacuum container 32 is maintained at 1P by adjusting the mass flow meter and the main valve of the main exhaust system. The substrate rotation speed is kept at 2 rpm. In this state, the shutter opening / closing control as described above is performed to manufacture the artificial lattice.

FIG. 4 is an exploded perspective view showing the shutter opening / closing control system. The rotation of the substrate rotation motor 36 is transmitted to the rotation introducing device 38, and the cylindrical substrate rotation holder 10 fixed to the lower end of the rotation introducing device 38 rotates in the direction of arrow 38. The six substrates 2 are attached to the substrate holder 10 as described above. Furthermore, the rotation introduction machine 3
A disk 40 is fixed to the disk 8, and one sensor rod 42 is fixed to the disk 40. Therefore, this sensor rod 42 also rotates at the same rotation speed as the substrate holder 10. On the other hand, the hollow disc 44 fixed to the vacuum container has two
A pair of photosensors 46 and 48 are installed on the circumference at an angle of 180 degrees. When the sensor rod 42 passes the photosensors 46 and 48, the fact is detected by the photosensor. And FIG.
The positional relationship between the sensor rod 42 and the substrate holder 10 is determined so that the sensor rod 42 passes through the first photosensor 46 at the substrate position (A position) shown in (A). Further, at the substrate position (position B) shown in FIG. 1B, the sensor rod 42 passes through the second photo sensor 48.

The outputs of the photosensors 46 and 48 are sent to the substrate position detecting device 50 to detect the substrate position. The output of the board position detecting device 50 is sent to the computer 52, and the position of the sensor rod 42 is displayed on the display thereof. A black dot 54 on the circumference of the display indicates the position of the sensor rod 42.
When the substrate holder 10 rotates, the black dots 54 also move circularly on the display. Further, the computer 52 can calculate the rotation speed and the number of rotations of the substrate holder 10 based on the output of the substrate position detecting device 50, and display the calculated result.

A shutter open / close signal is output from the computer 52 to a shutter control device 56, and the shutter control device 56 sends an on / off signal to a solenoid valve 58. As a result, the air pressure is controlled by the solenoid valve 58, and the shutter drive mechanisms 26 and 28 shown in FIG. 3 are controlled to be opened and closed. In this way, the timing of the rotation of the substrate holder 10 and the opening / closing of the shutters 16 and 18 are controlled.

Next, a method of determining the target input power will be described. An artificial lattice composed of a layer of a nitride of a 3d transition metal element and a layer of carbon nitride is expected to be applied to a soft X-ray optical material, and the graph of FIG. 5 shows a case where such an artificial lattice is manufactured. It shows the deposition rate of various nitrides used in. As for the sputtering conditions, in the apparatus shown in FIG. 3, the pressure of 100% nitrogen gas was set to 1 Pa,
The rotation speed of the substrate holder was 2 rpm. As a target, experiments were conducted on five types of Cu, Cr, V, C, and Ni, and the deposition rate when each nitride was deposited on the rotating substrate was measured. It should be noted that the deposition rate is an average value in the case of including all the time when the substrate faces the target and when the substrate does not face the target. The horizontal axis of FIG. 5 is the target input power, and the vertical axis is the deposition rate.

By the way, in order to deposit a certain nitride layer by 2.5 nm as the first layer or the second layer of the artificial lattice, the deposition thickness per rotation of the substrate is 2.5 nm or
Alternatively, it needs to be divided by an integer. Converting this to a deposition rate, the substrate rotates twice per minute, so it is necessary to set the deposition rate to 5.0 nm / min or an integral fraction thereof. In FIG. 5, the deposition rate is 5.0.
A broken line is drawn at nm / min. If the nitride layer is 2.5 nm, a deposition rate higher than this cannot be used. Therefore, 5.0 nm / min
The target power may be selected so that the deposition rate is equal to or a fraction of the integer. For example, in the case of a vanadium target, if a high frequency power of 185 W is applied,
A deposition rate of 1.25 nm / min was obtained, which was 5.
It is a quarter of 0 nm / min. Therefore, the deposition of vanadium nitride at this target power leaves the substrate at 1
During rotation, it deposits only 0.625 nm and after 4 rotations has a thickness of 2.5 nm. Also, in the case of a carbon target, it is 5.0 nm / m when a high frequency power of 240 W is applied.
A deposition rate of in is obtained. Therefore, depositing carbon nitride with this target power results in a thickness of 2.5 nm during one revolution of the substrate. [VN _x (2.5 nm) / CN _x (2.5 n
m)] ₃₀ artificial lattices were produced in the embodiment shown in FIG.

Next, as a second embodiment, [CrN _x
A procedure for producing an artificial lattice of (2.5 nm) / CN _x (2.5 nm)] ₃₀ will be described. In FIG. 1, the target 12 was chromium, and high frequency power of 190 W was applied to this to set the deposition rate of chromium nitride to 2.5 nm / min. In addition, carbon is used as the target 14 and 2
A high frequency power of 40 W was applied to set the carbon nitride deposition rate to 5.0 nm / min. The pressure of nitrogen gas and the substrate rotation speed are the same as in the first embodiment. FIG. 6 is a timing chart showing the procedure in this case. Open the chrome target shutter at position A and close the shutter after two turns. With this, 1.25n per rotation
m chromium nitride is deposited, and a total of 2.5 nm is obtained by two rotations. Next, the shutter of the carbon target is opened at the position B, and when the carbon target is returned to the original position B by one rotation, the shutter is closed. This deposits 2.5 nm of carbon nitride. This completes an artificial lattice for one cycle. This work is carried out for 30 cycles. In this embodiment, the substrate holder rotates four times to form one cycle, so the total required time is 60 minutes.

Next, as a third embodiment, [Cu ₃ N _x
A procedure for producing an artificial lattice of (2.5 nm) / CN _x (2.5 nm)] ₃₀ will be described. In FIG. 1, the target 12 is copper, and high-frequency power of 65 W is applied to it,
The copper nitride deposition rate was set to 5.0 nm / min. Further, the target 14 is carbon, and high frequency power of 240 W is applied to this to increase the deposition rate of carbon nitride to 5.0 nm.
/ Min. The pressure of nitrogen gas and the substrate rotation speed are the same as in the first embodiment. FIG. 7 is a timing chart showing the procedure in this case. The shutter of the copper target is opened at the A position, and when it returns to the original A position after rotating once, this shutter is closed. As a result, 2.5 nm of copper nitride is deposited. Next, the shutter of the carbon target is opened at the position B, and when the carbon target is returned to the original position B by one rotation, the shutter is closed. This deposits 2.5 nm of carbon nitride. This completes an artificial lattice for one cycle. This work is carried out for 30 cycles. In this embodiment, the substrate holder rotates three times to form one cycle, so the total required time is 45 minutes.

Next, as a fourth embodiment, [NiN _x
A procedure for producing an artificial lattice of (2.5 nm) / CN _x (2.5 nm)] ₃₀ will be described. In FIG. 1, the target 12 is nickel, and high-frequency power of 165 W is applied to this to increase the deposition rate of nickel nitride to 5.0 nm / min.
Set to. Further, the target 14 was carbon, and high frequency power of 240 W was applied to this to set the deposition rate of carbon nitride to 5.0 nm / min. The pressure of nitrogen gas and the substrate rotation speed are the same as in the first embodiment. The procedure for opening and closing the shutter is exactly the same as that shown in FIG. 7. Nickel nitride is deposited by 2.5 nm in one rotation from position A to position A, and carbon nitride is 2 in one rotation from position B to position B. Deposit only 0.5 nm. Therefore, the total required time is 45 minutes, which is the same as in the third embodiment.

Next, as a fifth embodiment, [CrN _x
A procedure for producing an artificial lattice of (2.5 nm) / CN _x (2.5 nm)] ₃₀ will be described. This artificial lattice is the same as that produced in the second embodiment (timing chart in FIG. 6), except that two chromium targets are used. FIG. 8 is a plan view showing the positional relationship between the target, the substrate and the shutter in the fifth embodiment. The difference from the arrangement of FIG. 1 is that a third target 13 is arranged in addition to the two targets 12 and 14. This target 13 is 60 in circumference with respect to the target 12.
It is just a few degrees away. Of course, the third photosensor for detecting the sensor rod is additionally installed at a position 60 degrees away from the photosensor for detecting the A position.

The targets 12 and 13 are chromium, and high frequency power of 190 W is applied to both of them to increase the deposition rate of chromium nitride by each chromium target to 2.5 nm.
/ Min. The target 14 was carbon, and high frequency power of 240 W was applied to the target 14 to set the deposition rate of carbon nitride to 5.0 nm / min. The pressure of nitrogen gas is 1 Pa and the substrate rotation speed is 2 rpm. First, the three shutters 16, 17 and 18 are closed.

First, in FIG. 8A, when the reference substrate 2a reaches the position A, the first shutter 16 is opened,
Chromium nitride is deposited to a thickness of 1.25 nm while the reference substrate 2a passes the facing position of the first target 12. Immediately after that, as shown in (C), when the reference substrate 2a comes in front of the third target 13 (this position will be referred to as C position), the third shutter 1 will be described.
7 is also opened, and chromium nitride is subsequently deposited to a thickness of 1.25 nm on this reference substrate 2a. As a result, the reference substrate 2a passes through the positions where the two targets 12 and 13 face each other, whereby chromium nitride having a total thickness of 2.5 nm is deposited. Chromium nitride is similarly deposited on the subsequent substrate. The first shutter 16 is closed when the reference substrate 2a makes one rotation and returns to the original position A, and the second shutter 1 is closed when the reference substrate 2a further moves to the position C.
7 is also closed. This deposits 2.5 nm of vanadium nitride on all substrates. From this state, the reference substrate 2
When a further reaches the position B shown in (B), the second shutter 18 is opened this time. As a result, carbon nitride is deposited with a thickness of 2.5 nm while the reference substrate 2a passes through the facing position of the second target 14. Then, when the reference substrate 2a returns to the position B, the second shutter 18 is closed. From this state, the reference substrate 2a is further
When returning to the position, one cycle ends. This one
During the cycle, the substrate holder 10 makes a total of 3 revolutions. FIG. 9 is a timing chart showing the procedure of this one cycle. The desired artificial lattice can be produced by repeating this operation for 30 cycles. Total time required is 4
5 minutes.

As described above, when two chromium targets and one carbon target are used (timing chart of FIG. 9), when one chromium target and one carbon target are used (timing chart of FIG. 6). ),
The total duration is reduced from 60 minutes to 45 minutes. Increasing the number of targets in this way is effective for shortening the film formation time. It is also possible to shorten the deposition time by increasing the target input power.
In that case, the number of rotations of the substrate holder may be increased so that the required film thickness (or an integral fraction thereof) is deposited by rotating the substrate holder once. In the apparatus of this embodiment, the substrate rotation speed can be increased up to 8 rpm.

A characteristic of each of the above-described embodiments is that, for a target (copper, nickel, or carbon) having a relatively high deposition rate, the target input power is set so that the required film thickness can be deposited by one rotation of the substrate holder. On the other hand, for targets with relatively low deposition rates (vanadium and chromium),
The target input power is set so that the required film thickness can be deposited by rotating the substrate holder multiple times. This will give all targets
It is possible to use the power region where the deposition rate is relatively stable,
It became possible to control the accuracy of the film thickness at the level of 0.1 nm.

The present invention is not limited to the above-mentioned embodiment, but the following modifications are possible.

(1) Instead of providing two or three photosensors for detecting the sensor rod, only one photosensor may be provided. In this case, for example, only the A position is detected by the photo sensor, and the other B position or C position is 1 from the A position.
It is calculated by a computer as if it were rotated by 80 degrees or 60 degrees.

(2) The present invention can be applied not only to the artificial lattice of nitride but also to a method of producing an artificial lattice made of another material.

(3) In the case of manufacturing an artificial lattice composed of three types of layers, a deposition step of the third layer is added after the deposition steps of the first layer and the second layer, and this is repeated for one cycle. And it is sufficient.

(4) As shown in FIG. 10, a circular flat plate type substrate holder may be used. In the illustrated example, the two targets 60 and 62 and the substrate holder 64 face each other in parallel, and the rotation axis of the substrate holder 64 is perpendicular to the substrate surface. Four substrates 66 are attached to the substrate holder 64, and the substrate holder 64 rotates in the direction of arrow 68 at a constant speed. Shutters (not shown) are individually arranged between the targets 60 and 62 and the substrate holder 64, and an artificial lattice can be manufactured by controlling opening / closing of these shutters. The manufacturing procedure is basically the same as when a cylindrical substrate holder is used.

[0054]

According to the method for producing an artificial lattice of the present invention, even when two types of layers having greatly different deposition rates are alternately deposited, by controlling the opening / closing timing of the shutter, An input power region with a stable deposition rate can be used, and precise film thickness control is possible. In addition, there are less restrictions on the board layout, and productivity is also improved.

[Brief description of drawings]

FIG. 1 is a plan layout view showing an embodiment of the present invention.

FIG. 2 is a timing chart showing the procedure of an embodiment of the present invention.

FIG. 3 is a plan cross-sectional view showing the overall configuration of an artificial lattice production device.

FIG. 4 is an exploded perspective view showing a shutter opening / closing control system.

FIG. 5 is a graph showing the deposition rates of various nitrides forming the artificial lattice.

FIG. 6 is a timing chart showing the procedure of the second embodiment.

FIG. 7 is a timing chart showing the procedure of the third embodiment.

FIG. 8 is a plan view showing an arrangement relationship between a target, a substrate, and a shutter in a fifth embodiment.

FIG. 9 is a timing chart showing the procedure of the fifth embodiment.

FIG. 10 is a perspective view when a flat plate type substrate holder is used.

FIG. 11 is a plan layout view showing a conventional method.

[Explanation of symbols]

 10 Substrate Holder 12 First Target 14 Second Target 16 First Shutter 18 Second Shutter 2a to 2f Substrate L Target Target Area

Claims (9)

[Claims] 1. A method for producing an artificial lattice in which two kinds of deposited layers are periodically repeated on a substrate by sputtering a plurality of targets, wherein the substrate circulates and moves while facing the plurality of targets in order. So as to move the substrate at a constant speed, a shutter for the first layer deposition target (hereinafter referred to as the first shutter) and a shutter for the second layer deposition target (hereinafter referred to as the second shutter). , And a predetermined power is applied to the first layer deposition target and the second layer deposition target, respectively, and when the substrate is not at a position opposite to the first layer deposition target. Opening the first shutter; closing the first shutter after the substrate has passed a facing position of the first layer deposition target a predetermined number of times. Opening the second shutter when the substrate is not in the facing position of the second layer deposition target, and closing the second shutter after the substrate has passed the facing position of the second layer deposition target a predetermined number of times. And a step of repeating the step of opening the first shutter to the step of closing the second shutter a predetermined number of times. 2. The method for producing an artificial lattice according to claim 1, wherein a plurality of substrates are attached to a movable substrate holder, and the artificial lattice is simultaneously produced on the plurality of substrates. 3. The method for producing an artificial lattice according to claim 2, wherein a plurality of substrates are attached to the substrate holder so that all the substrates do not face any target. 4. The film thickness that can be deposited on the substrate by the target for depositing the first layer is the required film thickness of the first layer during the elapsed time until the substrate returns to the original position (hereinafter referred to as the circulation required time). The substrate is formed so that the film thickness can be 1 / integral and the film thickness that can be deposited on the substrate by the second layer deposition target during the circulation time is 1 / integral of the required film thickness of the second layer. 2. The method for producing an artificial lattice according to claim 1, wherein the moving speed of the target, the input power of the first layer deposition target and the input power of the second layer deposition target are adjusted. 5. The moving speed of the substrate and the input power of the target for depositing the first layer such that the deposited film thickness of the first layer or the second layer during the circulation required time becomes equal to the required film thickness of the layer. The method for producing an artificial lattice according to claim 1, wherein the input power of the target for depositing the second layer is adjusted. 6. The artificial lattice according to claim 1, wherein the substrate is attached to a cylindrical surface of a cylindrical substrate holder, and the substrate holder is rotated around a center line of the cylindrical surface. Manufacturing method. 7. The method for producing an artificial lattice according to claim 1, wherein the substrate is attached to a flat plate type substrate holder, and the substrate holder is rotated about an axis perpendicular to the plane. 8. The method for producing an artificial lattice according to claim 1, wherein at least one of the first layer deposition target and the second layer deposition target is a plurality of targets. 9. In a method for producing an artificial lattice in which n (n is an integer of 3 or more) kinds of deposition layers are periodically repeated on a substrate by sputtering a plurality of targets, the plurality of targets are sequentially opposed to each other. While moving the substrate at a constant speed so that the substrate circulates and moves, and applying predetermined power to each target with each shutter closed, A step of opening a shutter for the first layer deposition target (hereinafter referred to as a first shutter) when the first layer deposition target does not face the first layer deposition target; For closing the first shutter after passing the number of times and for each of the second layer deposition target to the nth layer deposition target, In the same manner as in the case of the above-mentioned target for depositing the first layer, the steps from the step of opening the shutter to the step of closing the shutter are performed, and from the step of opening the first shutter, the shutter for the target for depositing the n-th layer is closed. And a step of repeating steps up to a predetermined number of times.