JPH0156141B2 - - Google Patents

Description

Detailed Description of the Invention <Industrial Application Field> The present invention is applicable to the production of periodic multilayer thin films, superlattice structure thin films, or artificial lattice structure thin films that have highly accurate periodicity and have a single layer thickness. The present invention relates to a method and apparatus for producing a multilayer thin film that can uniformly produce an artificial lattice structure film of several nanometers or less over a large area.

<Prior Art> Conventionally, there are the following two methods for manufacturing this type of multilayer thin film.

The first method is the report "Artificial lattice alloy film" written by Teruya Shinjo in the academic journal "Solid State Physics" published by Agnes Publishing, Vol. 18, No. 5 (1983), p. p. 271-277.
is shown. That is, as shown in FIG. 4, a substrate holder electrode 2 to which a thin film forming substrate 1 is attached is arranged in a vacuum chamber 13, and targets A and B of different types are irradiated with electron beams 14 and 15. In this method, the shutters 6 and 7 for targets A and B are alternately opened and closed to alternately form the substances constituting the targets A and B on the thin film forming substrate 1. In this method, the shutter 6 is opened, and when the substance constituting the target A is formed as a thin film (hereinafter referred to as A film) on the substrate 1 to a thickness d _A , the shutter 6 is closed. At this time, the film thickness is controlled by time or by a film thickness measurement monitor. Next, open shutter 7,
When the material constituting the target B is formed as a thin film (hereinafter referred to as B film) on the substrate 1 to a thickness d _B , the shutter 7 is closed. By repeating this procedure n times, the thickness (d _A + d _B ) × n
A periodic AB multilayer film is formed. However, with this method, although it is possible to make the sum of the film thicknesses (d _A + d _B ) of the AB film in each period uniform over the entire surface of the substrate, the film thickness d _A or d of each layer in each period is _B is non-uniform because the configuration of the device is not bilaterally symmetrical as shown in FIG. Therefore, it is difficult to make the film thicknesses d _A and d _B uniform over a wide area. On the other hand, if the deviations when laminating n layers of AB films are Δd _A and Δd _B , then the film thickness accuracy Δd _A /d _A and Δd _B /d _B depend on the control of the film thickness, and the shutter open state time The shutter opening/closing time error becomes a problem in the control method, and in the film thickness measurement monitoring method, when the film thicknesses d _A and d _B become extremely thin layers on the order of 5 to 10 Å, a substantial error occurs, and Δd _A /d _A , Δd _B /
d _B is about 0.1 to 0.05. Although there are the above two drawbacks, it is particularly difficult to solve the former drawback of not being able to achieve uniformity over a large area. In addition, in FIG. 4, 3 and 4 are cathode electrodes.

On the other hand, the second method that is advantageous for making d _A and d _B uniform over a large area is the academic journal "Physical Review B" published by the American Physical Society, Vol. 26, No. .9, p.p4894
~4908, the paper “Superconducting Property of Nb−Ge metal” by ST Ruggiero et al.
Semiconductor multilayers”.
That is, as shown in FIGS. 5a and 5b, a plurality of about 2 to 6 substrates 1 are attached to the substrate holder electrode 2, and a recirculating mechanism (not shown) is attached to the substrate holder electrode 2. It is designed to rotate at a constant rotation speed. Targets A and B made of different materials are placed on cathode electrodes 3 and 4 below the substrate holder electrode. Shutters 6 and 7 are provided for each target A and B, respectively.
is designed to open and close by rotation. Further, between the shutters 6 and 7 and the substrate holder electrode 2, a film thickness correction plate 5 having a fan-shaped window 5a is installed. The film thickness correction plate 5 has a disk shape, and as shown in FIG. none,
This serves to make the film thickness distribution uniform on the substrate 1.

Therefore, according to this device, the substrate holder electrode 2
Targets A and B while rotating at a constant speed.
Since the laminated films can be formed alternately by , the film thickness distribution in the circumferential direction of rotation can be easily made uniform, and furthermore, by optimizing the opening shape of the window portion 5a of the film thickness correction plate 5, ± the radial film thickness distribution
It can be reduced to 1% or less. Specifically, FIG. 6 shows a flowchart of the AB multilayer film forming process using this apparatus. When films A and B are alternately stacked on a substrate, if the film thickness of each layer is d _A and d _B , first the film thicknesses formed per rotation at the same rotation speed are d _A and d _B. The electric power (sputter speed) of sputter discharges A and B and the rotation speed of the substrate holder electrode are set so that the following results are obtained. Next, shutters 6 and 7 are opened simultaneously to perform sputtering. As a result, a laminated film with the sum of film thicknesses (d _A + d _B ) is formed every time it rotates, and after sputtering is performed up to the preset number of revolutions N _nax ,
When the shutters 6 and 7 are closed to complete film formation, an AB multilayer film having a film thickness (d _A + d _B )×N _nax is formed.

As a result, when using a 150mmφ target,
Film thickness distribution ±1 for an area of 10 cm in the radial direction
% or less is possible. On the other hand, in the circumferential direction of rotation, the film thickness distribution is determined by the rotational accuracy, and since the rotational accuracy of a normal sputtering device is ±5%, a film thickness distribution of ±5% can be obtained. Therefore, the film thickness distribution ±
If it is 5%, it is relatively easy to uniformize a large area of 10 cm x 20 cm square.

<Problem to be solved by the invention> However, in order to accurately create an artificial lattice thin film structure, the film thickness distribution must be within ±1%, and the film thickness accuracy of each layer Δd _A /d _A , Δd _B /d _B ±1%
However, in the above-mentioned apparatus, it is extremely difficult to maintain the distribution in the circumferential direction of rotation within ±1%. An experiment was conducted using a combination of a high-precision drive motor and a high-precision gear, but the rotational precision obtained was limited to ±2%.

The present invention has been made in view of the above-mentioned prior art, and by forming an aggregate of two or more laminated layers made of a single substance, the film thickness distribution is made uniform, and the film thickness of each layer is reduced. It is an object of the present invention to provide a method and apparatus for manufacturing a multilayer thin film that can reduce deviation.

<Means for Solving the Problem> The structure of the method for manufacturing a multilayer thin film of the present invention that achieves the above object includes a cathode electrode on which a plurality of types of targets each made of a different substance are placed, and a substrate attached. By arranging the substrate holder electrodes facing each other and applying a voltage between these electrodes to cause sputter discharge, and further rotating the substrate holder electrode at a constant rotation speed, the substance constituting the target is removed. In the method for manufacturing a multilayer thin film that is laminated as a thin film on the substrate, a plurality of shutters corresponding to each of the targets are installed between the electrodes, and each time a plurality of rotations of the substrate holder electrode are detected, By repeatedly opening and closing the shutters selectively,
The multilayer thin film is characterized in that each layer made of a single substance is formed of two or more laminated thin films.

On the other hand, in the structure of the multilayer thin film manufacturing apparatus of the present invention which achieves the above object, a cathode electrode on which a plurality of types of targets made of different materials are placed, and a substrate holder electrode on which a substrate is attached are placed facing each other. The substance constituting the target is laminated as a thin film on the substrate by arranging the target and applying a voltage between these electrodes to cause sputter discharge, and further rotating the substrate holder electrode at a constant rotational speed. In the multilayer thin film manufacturing apparatus, a rotation detection sensor is provided to detect the number of rotations or the rotation speed of the substrate holder electrode, and a plurality of shutters corresponding to each of the targets are installed between the electrodes so as to be able to be opened and closed independently. Further, by providing a control unit that repeatedly selectively opens and closes the shutter each time the rotation detection sensor detects a plurality of rotations of the substrate holder electrode, the multilayer thin film can be made of a single substance. Each layer is formed of two or more laminated thin films.

<Operation> A voltage is applied between the substrate holder electrode and the cathode electrode, the substrate holder electrode is rotated at a constant rotation speed, one of the shutters for multiple types of targets is opened, and the remaining shutters are closed. shall be. For example, when two types of targets A and B are used as shown in FIG. 1, when opening shutter 7 for target B, target A
Close the shutter 6. Then, the substrate holder electrode 2 rotates R _Anax times (R _Anax > ^/22 ), and two or more layers of the A film are stacked on the substrate, and the thickness of the A film as an aggregate becomes a certain film thickness d _A. 7, close shutter 7 for target B, and
Open shutter 6 about. Further, the substrate holder electrode 2 rotates R _Bnax times (R _Bnax > ^/22 ), and two or more layers of the B film are stacked on the substrate, and the thickness of the B film as an aggregate becomes a certain film thickness d _B. The substrate holder electrode 2 is rotated until the substrate holder electrode 2 is rotated. By repeating this procedure N _nax times, a multilayer thin film consisting of the A film and the B film is formed on the substrate. Here, if the deviations of each film thickness are Δd _A and Δd _B , then the film thickness accuracy is Δd _A /d _A , Δd _B /d _B
are the rotational accuracy of the substrate holder electrode 2, respectively.
Since R ^-1/2 _Anax times and R ^-1/2 _Bnax times, the rotation speed
It can be seen that by increasing R _Anax and R _Bnax , they decrease hyperbolically.

<Example> Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1, 2, and 3. FIG. 1 shows the multilayer thin film manufacturing apparatus 2 of this embodiment.
2 is a control block diagram, and FIG. 3 is a flowchart of the method for manufacturing a multilayer thin film of this embodiment.

As shown in FIG. 1, a plurality of thin film forming substrates 1 are attached to the substrate holder electrode 2, and a rotation mechanism consisting of a motor 9 is attached, allowing the substrate holder electrode 2 to rotate around a central axis. It's becoming like that. The rotational speed or rotational speed of the substrate holder electrode 2 is detected by a rotation detection sensor 8, converted into an electrical output proportional to each by a rotational speed counter 10 and a tachometer 11, and sent to a control section 12.

Cathode electrodes 3 and 4 are provided below the substrate holder electrode 2, on which targets A and B made of different materials are placed. Power is supplied to the cathode electrodes 3 and 4 by the control section 12 so that a predetermined voltage is applied to the substrate holder electrode 2.

Furthermore, cathode electrodes 3 and 4 and substrate holder electrode 2
In between, shutters 6 and 7 are provided for targets A and B, respectively. Are these shutters 6 and 7 almost the same shape as targets A and B?
Or, it has a shape larger than that, and is driven linearly back and forth as shown by the arrows in the figure to open and close targets A and B independently. As shown in FIG. 1, the shutters 6 and 7 can be driven in a reciprocating manner using, for example, a voice coil motor, but a rotating mechanism may also be used. It's becoming controlled.

The control unit 12 feedback-controls the rotational speed of the substrate holder electrode 2 to a constant level using the motor 9 based on input signals from the rotational speed counter 10 and the rotational speed detector 11, and causes sputter discharge to the cathode electrodes 3 and 4. Feedback control of power to a constant level. Furthermore, as shown in FIG. 2, the rotation speed of the substrate holder electrode 2 is set to a preset rotation speed R _Anax ,
The shutters 6 and 7 are selectively opened and closed for each R _Bnax .

The multilayer thin film manufacturing apparatus 20 of this embodiment having the above-mentioned configuration is carried out, for example, according to the flowchart shown in FIG.

First, a predetermined sputter discharge voltage and a predetermined rotation speed of the substrate holder electrode are set, and preliminary sputtering is performed. Next, the shutter 6 is opened (the shutter 7 is closed), and the rotation detection sensor 8 detects the rotation speed.
Until R _Anax was detected, the substance constituting target A was laminated on substrate 1 as A film R _Anax times.
At this time, the film thickness of the A film as an aggregate is assumed to be _dA . Next, close shutter 6 and close shutter 7.
is opened, and the material constituting the target B is placed on the substrate 1 until the rotation detection sensor 8 detects the rotation speed R _Bnax .
R _Bnax was layered on top as a B film. The film thickness of the B film as an aggregate at this time is assumed to be _dB . A multilayer thin film is formed by repeating this operation N _nax times.

Here, if the respective deviations of the film thickness d _A and film thickness d _B as an aggregate are Δd _A and Δd _B , then the film thickness precisions Δd _A /d _A and Δd _B /d _B of the substrate holder electrode 2 are The rotational accuracy will be multiplied by R ^-1/2 _Anax and R ^-1/2 _Bnax , respectively. For example, the rotation accuracy of the substrate holder electrode 2 should be set to ±2.
If %, R _Anax , and R _Bnax are 4 rotations and 16 rotations,
Δd _A /d _A and Δd _B /d _B are as small as ±1% ±0.5%.

As a comparative example, carbon and tungsten were used as targets A and B of 150 mmφ, carbon sputter discharge power was 800 W, tungsten sputter discharge power was 240 W, Ar gas pressure was 5×10 ^-3 Torr, substrate rotation speed was 1 rpm, and R _Anax = 1, R _Bnax = 1, N _nax
A C/W multilayer film of (C film 16 Å + W film 24 Å)×50 layers was created on a mirror-finished 4-inch Si (111) wafer substrate under the condition of = 50. Radial film thickness distribution, X
The distribution of the artificial lattice spacing determined from line diffraction is good at ±0.8%, but the distribution in the circumferential direction is ±1.5% for the film thickness distribution and ±1.5% for the artificial lattice spacing.
It was 1.4%. Further, the film thickness accuracy Δd/d at one position was ±2.1%. On the other hand, as an example, the substrate rotation speed is 18 rpm, R _Anax = 9,
Under the conditions of R _Bnax = 9 and N _nax = 50, the other conditions were the same as in Example 1.
A C/W multilayer film of 50 layers (16 Å + W film 24 Å) was formed. The film thickness distribution in the radial direction and the distribution of the artificial lattice spacing are ±0.8% as in Example 1, but the film thickness distribution in the circumferential direction is below the film thickness measurement accuracy (1% or less), and the artificial lattice spacing is ±0.8%. ±0.5%, Δd/d is ±0.7
%, which was extremely good. When forming a single layer of carbon film or tungsten film in this way,
By rotating the substrate multiple times to reduce statistical errors due to uneven rotation, variations in the periodic stacking of each layer can be reduced.

In addition, although the above-mentioned example illustrated a multilayer thin film production method in which a plurality of target substances are alternately coated on a substrate by a sputtering method, it is possible to use electron beam heating, high frequency heating, or resistance heating melting method instead of the sputtering method. A plurality of these substances may be deposited and alternately coated on the substrate.

<Effects of the invention> As explained above, while rotating the substrate,
In a method in which thin films sputtered from more than one target are alternately laminated on a substrate, the opening/closing operation of the shutter is synchronized with the set number of times of the substrate, which has the advantage of reducing unevenness in the thickness of each layer due to uneven rotation. . In addition, using the apparatus of the present invention, not only can a multilayer thin film be fabricated by interlocking the shutter and the substrate rotation speed, but also the target materials can be changed to Nb, Si,
By combining Nb and Al, Nb and Sn, and Nb and Ge, it is possible to form an artificial lattice shape alternately according to the periodic length of the A15 structure, which exhibits superconductivity. For example, Nb
and Si for Nb at substrate temperature range of 600℃~300℃
When layering 2 to 3 Å of Si and Si, A15
Generation of phases was confirmed by X-ray diffraction. Therefore, the present invention has an advantage in producing an artificial lattice film having extremely high precision periodicity and a thermally non-equilibrium structural film.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the multilayer thin film manufacturing apparatus according to the present invention, FIG. 2 is a block diagram regarding control, FIG. 3 is a flowchart of the operation sequence of the multilayer thin film manufacturing apparatus of FIG. 1, and FIG. A schematic configuration diagram of an apparatus used in a conventional method for producing a multilayer thin film, FIGS. FIG. 3 is a flowchart of the working order of the apparatus shown in the figure. In the figure, 1 is a thin film forming substrate, 2 is a substrate holder electrode, 3 and 4 are cathode electrodes, A and B are targets (made of different substances), 6 and 7 are shutters, 8 is a rotation detection sensor, 9 is the motor, 10
is a rotation detection counter, 11 is a rotation speed detector, 1
2 is a control unit, and 20 is a multilayer thin film manufacturing apparatus.

Claims (1)

[Claims] 1. A cathode electrode on which a plurality of types of targets made of different substances are placed and a substrate holder electrode on which a substrate is attached are placed facing each other, and a voltage is applied between these electrodes. A method for manufacturing a multilayer thin film in which a substance constituting the target is laminated as a thin film on the substrate by applying a sputter discharge and rotating the substrate holder electrode at a constant rotational speed. A plurality of corresponding shutters are installed between the electrodes, and each time a plurality of rotations of the substrate holder electrode are detected, selective opening and closing of the shutters is repeated, whereby a single substance is formed in the multilayer thin film. 1. A method for producing a multilayer thin film, characterized in that each layer is formed from a laminated thin film of two or more layers. 2 A cathode electrode on which multiple types of targets made of different materials are placed and a substrate holder electrode on which a substrate is attached are placed facing each other, and a voltage is applied between these electrodes to cause spatter discharge. Further, in a multilayer thin film manufacturing apparatus in which a substance constituting the target is laminated as a thin film on the substrate by rotating the substrate holder electrode at a constant rotation speed, the rotation number or rotation speed of the substrate holder electrode is controlled. A rotation detection sensor is provided to detect the substrate holder electrode, and a plurality of shutters corresponding to each of the targets are installed between the electrodes so as to be able to be opened and closed independently, and the rotation detection sensor detects multiple rotations of the substrate holder electrode. Each layer of the multilayer thin film made of a single substance is formed by a laminated thin film of two or more layers by providing a control unit that repeats selective opening and closing of the shutter each time the shutter is opened and closed. Multilayer thin film manufacturing equipment. 3. The method or apparatus for manufacturing a multilayer thin film according to claim 1 or 2, wherein the shutter has a shape equal to or larger than the shape of the target corresponding to the shutter. 4. The method or apparatus for manufacturing a multilayer thin film according to claim 1 or 2, wherein the shutter opens and closes independently by linear reciprocating movement.