JPS61250163A - Method and apparatus for production of multi-layered thin film - Google Patents

Abstract

PURPOSE:To form multi-layered thin films having a uniform film thickness in a manner as to have periodicity of high accuracy by passing successively prescribed times the substrates attached to a substrate holder electrode rotating at a specified rotating speed on the sputtering paths of plural different targets. CONSTITUTION:The substrates 1 are attached to the substrate holder electrode 2 rotated at the specified rotating speed by a motor 9 and a voltage is impressed to cathodes electrodes 3, 4 carrying the plural targets A, B consisting of materials different from each other to generate a sputter discharge, by which the sputter films of the materials of the above-mentioned targets A, B are successively and alternately laminated respectively at specified periods on the substrates 1 and the multi-layered thin films are formed thereon. The thin films are successively formed to the prescribed film thickness in the above-mentioned method by detecting the rotation of the above-mentioned substrate holder electrode 2 with a sensor 8 and a counter 10, speed detecting part 11, etc., controlling shutters 6, 7 by a control part 12 to open the sputtering paths for the desired targets A, B, etc. and passing prescribed times the substrates 1 through said paths.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method and apparatus for producing a multilayer thin film in which thin film layers made of different materials are sequentially and alternately laminated, and more specifically, to a method and apparatus for producing a thin film having a uniform thickness. The present invention relates to a method and apparatus for manufacturing multilayer thin films that are sequentially and alternately laminated with precision.

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

The first method is described in the academic journal "Solid State Physics" published by Agnes Publishing, Vol. 18, No. 5 (1983), p. 271-27.
7, in the report "Popular lattice alloy film" written by Teruya Shinjo, as shown in FIG. A multilayer film manufacturing method is disclosed in which thin films of substances A and B are alternately laminated on a thin film forming substrate 1 by irradiation with an electron beam 14.15.

The second method is described in the academic journal “Physical Review B” published by the American Society of Physics.
J Vol. 26, & 9, p. 4894-4908, S. T.

Ruggiero and 2 other authors' papers r Supercon
CluetingProperty of Nb-Ge
metal semiconductor multi
In layersJ, cathode electrodes 3 and 4 each having a plurality of targets made of different substances are arranged below a substrate holder electrode 2 to which a film forming substrate 1 is attached, and a sputtering voltage is applied to the cathode electrodes to remove the targets. While sputtering, the substrate holder electrode ff11
2 around its central axis, and using a film thickness correction plate 5 between the target and the substrate holder electrode,
In order to make the film thickness distribution in the radial direction of the film uniform, a plurality of different openings are inserted through the film thickness correction plate 5, which has a fan-shaped opening with a small diameter in the direction of the rotation axis of the substrate holder electrode 2 and a large diameter in the circumferential direction. It is disclosed that target materials A and B made of materials are sputtered so as to be alternately stacked. That is, as shown in FIG. 5(aL(b)), the apparatus is composed of a rotating mechanism/substrate holder electrode 2, a substrate 1, a shutter 6.7, cathode electrodes 3 and 4, targets A and B, and a film thickness correction plate 5. At the same time, 2 to 6 substrates 1 are attached to the substrate holder electrode 2, and the target A is attached while rotating the substrate holder electrode.
, B are alternately sputtered to form a laminated film. In order to make the film thickness distribution uniform in the circumferential direction of the substrate being rotated by the rotating mechanism, and also to make the film thickness distribution in the radial direction uniform, the sputtered material from the targets A and B is spread in a large circle in the circumferential direction. It is laminated onto a substrate through a small circular fan-shaped opening in the axial direction.

This sputter deposition layer forming step is performed according to the flowchart shown in FIG.

When forming a multilayer thin film of sputtered material A→B−hA→B→... on a substrate, the thickness of each layer must be carefully controlled.

9, first set the power (sputtering speed) of sputtering discharges A and B and the rotational speed of the substrate holder electrode so that the film formed per rotation at the same rotational speed is "A-dB".Next, the shutter 6 and 7 are opened at the same time to perform sputtering.This forms a laminated film of (dA and 10 dB) each time it rotates, and after performing sputtering up to the preset number of revolutions N, shutters 6 and 7 are closed. After completing the film formation,
(dA+dB) X N, , a layer is formed. According to this method, when using a target with a diameter of 150 cylinders,
Film thickness distribution ±1% for a 10cm area in the radial direction
The following 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 normal sputtering equipment is ±5%, the film thickness distribution is ±5%.
is obtained.

Therefore, if the film thickness distribution is ±5%, 10 cm
It is easy to coat a large area of 20 cm square with a uniform thickness.

<Problems to be Solved by the Invention> However, in the first method, even though it is possible to make the film thickness of the pair forming the first period of (dA+dl,) uniform over the entire surface of the laminated layer on the substrate, d However, the thickness of each layer of aa has a distribution in the left-right direction of the substrate in FIG. 4 due to the structure of the device. For this reason, it is difficult to make the particles uniform over a wide area. In addition, variations in stacking n layers of (dA+d,) pairs exist, ΔdA, Δ, and variations in opening/closing shutter time become a problem in the method of managing the time when the shutter is open.

In particular, in the case of the film thickness measurement monitoring method, dA and dB are 5 to 1
When the layer becomes extremely thin, on the order of 0 people, a substantial error occurs, reaching approximately ΔdA/dA and ΔdA/dB of 0.1 to 0.05. Although there are the above two drawbacks, it is particularly difficult to make the former uniform over a large area.

Further, in the second method, when a target of 150 nmφ is used as described above, the film thickness distribution can be made to be ±1% or less in an area of 10 cm in the radial direction. In addition, the film thickness distribution in the direction of rotation of the base holder electrode is determined by the rotational accuracy, and in normal sputtering equipment, the rotational accuracy is ±
5%, the film thickness distribution is ±5%. Therefore, if the film thickness distribution is ±5%, 10 cm x 20 cm
A large area of m square area can be coated with a uniform thickness. However, in order to create a multilayer thin film structure with high precision, the film thickness distribution must be within ±1%, and the variations in dA and dl of each layer, ΔdA/dA and Δde/'a, must be within ±1%. , in the above device, the distribution in the rotational circumferential direction is ±1%.
It is extremely difficult to keep it within this range. 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%.

This invention was made to eliminate the above-mentioned drawbacks in conventional multilayer thin film manufacturing methods, and involves applying a voltage between a substrate holder electrode and a cathode electrode having a plurality of targets made of different materials. The substrate is passed over the cathode electrode while causing sputter discharge and rotating the substrate holder electrode at a constant speed.

A method for manufacturing a multilayer thin film in which different target materials are alternately laminated on a substrate, in which thin films of each target material with little variation in film thickness are sequentially and alternately laminated with high precision periodicity. This is what we are trying to provide.

Further, the present invention aims to provide a multilayer thin film manufacturing apparatus suitable for the method for manufacturing multilayer thin films such as B.

Means for Solving the Problems> A method for producing a multilayer thin film according to the present invention to achieve the above object uses sputtering by applying voltage to a substrate holder electrode and an electrode having a plurality of targets made of different materials. In a method for manufacturing a multilayer thin film, in which a substrate holder electrode to which a substrate is attached is rotated at a constant rotational speed while discharging, sputtered films of each of the target materials are sequentially and alternately laminated on the substrate at a constant period. When coating each sputter layer, the sputtering path for the target material is opened while the substrate holder electrode is rotated at a constant rotation speed, and the substrate is passed over the sputtering path a predetermined number of times, thereby sputtering the target material. After forming the layer to a predetermined thickness, there is a step of closing the sputtering path for that target material, and following this step, opening a sputtering path for another target material, and then connecting the substrate holder electrode to the sputtering path of the target material in the same way as in the previous step. The method is characterized in that the sputtered layers of each target material are alternately stacked by repeating the process of passing the target material through a road to deposit a sputtered film of the target material to a predetermined thickness and then closing the sputtering path. be.

In addition, in the above-mentioned method for manufacturing a multilayer thin film, each target material may be sequentially and alternately laminated at a constant period through a radial sputtered film thickness equalization film thickness correction plate placed between the target and the substrate holder electrode. .

Further, as the film thickness correction plate, one having a fan-shaped opening having a small diameter in the direction of the rotation axis of the substrate holder electrode and a large diameter in the circumferential direction may be used.

In addition, the multilayer thin film manufacturing apparatus of the present invention is used to apply sputter discharge power to a cathode electrode having a substrate holder electrode plate and a plurality of targets made of different materials disposed on the substrate holder side of the substrate holder electrode plate facing the substrate. a drive source that rotates the substrate holder electrode plate around its central axis; a rotation detection sensor that detects the number of rotations and rotational speed of the substrate holder electrode plate; shutter means each disposed between a plurality of cathode electrodes and opening and closing a sputter evaporation path for the target material; It is characterized by comprising control words for adjusting opening/closing, discharge power to the cathode electrode, and drive power to the drive source.

As described above, in the method for producing a multilayer thin film of the present invention, when coating a sputter layer of each target material, the sputtering layer of the target material is sputtered while the substrate holder electrode is rotated at a constant rotation speed. A film forming substrate attached to a substrate holder electrode is passed through the sputtering path a predetermined number of times using a sputtering path to form a sputtered layer of the target material to a predetermined thickness, and then the sputtering path of the target material is closed, Opening the sputtering path for another target material, passing the substrate-holder electrode over the sputtering path of the target material, coating the target with a predetermined sputtering film thickness, and closing the sputtering path is repeated N, @8 times. Then, the sputtered layers of each target material are alternately laminated, so for example, the sputtering paths are opened for each target material A and B, and the substrate holder electrode is rotated RAIIImM and RBmsx times to obtain film thicknesses dA, dl! When one pair formed in 1 is laminated by N,...q, the film thickness becomes -+R11111111 times. Therefore, RAMsx
' If RBIIIIN is increased to 4 rotations or 16 rotations, ΔdA/dA, Δd, /dB can be reduced to ±1% or ±0.5%.

EXAMPLES> The content of the present invention will be specifically explained below with reference to Examples.

1 to 3 show the schematic configuration of an apparatus used in the method of manufacturing a multilayer thin film of the present invention, FIG. 2 is a configuration diagram of the apparatus 20 shown in FIG. 1, and FIG. FIG. 3 is a block diagram of the control section, and is a flowchart of the work order of the apparatus shown in FIG. 1.

The apparatus 20 shown in FIG. 1 is composed of mutually different materials A disposed below a substrate holder electrode 2 to which a thin film forming substrate 1 is attached.
, B, a shutter 6.7 that opens and closes the sputtering path between the targets A and 8 by protruding and retracting using electric power supplied from a power supply not shown, and a substrate holder electrode. 2 has a rotation detection sensor that detects the rotation speed and number of rotations, and a motor 9 that rotates the substrate holder electrode 2 around a central axis.

Furthermore, the substrate holder electrode 2 obtained with a rotation detection sensor
Electrical output proportional to the rotational speed and rotational speed 10,11
is sent to the control unit 12, and controls the shutter driving power from a power source (not shown) supplied to the shutter 6°7 via the control unit 12, as well as feedback control of the power to the motor 9 and cathode power S3, 4. Then, the substrate rotation speed and sputter discharge are controlled to be constant.

In FIG. 1, the shutters 6 and 7 may be driven to open and close by using a voice coil motor, for example, and a mechanism that rotates the shutters while reciprocating them.

Using the sputtering apparatus shown in Fig. 1, target materials A and B are
f) To form the i@ thin film by sputtering, the process is carried out, for example, according to the flowchart shown in FIG.

That is, the sputtered film C of target material A will be referred to as "A film", and the sputtered film of target material B will be referred to as "B film". ) is formed by the number of substrate rotations, one layer of B film is formed by the number of substrate rotations, and this is done alternately to form a pair layer of (dA+dB) N , when forming only eight layers, predetermined sputter discharges A and B and a predetermined substrate rotation speed are set by the control unit 12 shown in FIG.
Perform preliminary sputtering. Next, the shutter 6 is opened and the film A is formed until the number of revolutions reaches RA□ times, and then the shutter 7 is opened and the film B is formed until the number of revolutions reaches RIIIIIIX times. As a result, (dA+d,
) is formed, and this process is repeated for N1.8. As a result, ΔdA/dA, Δd8/dl.

are -+-+ RAffi and 8 times' R111111111 times, respectively, for a variation of substrate rotation speed of ±2%. Therefore, R@X'RB□, K rotates 4 times, 1
Assuming 6 rotations, Δd,/bug.

Δda/'a can be made as small as ±1% or ±0.5%.

As an example, target A is 150 mφ.

B and groove are carbon (C) and tungsten (B) respectively.
Using C sputter discharge 800W, W sputter discharge 240W, Ar gas pressure 5X10 Torr1 substrate rotation speed, 1 rP m'RAmmy+=1, RBI?
4 with mirror finish under the conditions of 1lI11 = 1, N = 50
A C/W multilayer film with 50 layers (16 C films and 24 W films) was created on an inch S i (111) substrate. The film thickness distribution in the radial direction and the distribution of the population lattice spacing determined from xNs diffraction are both good at 0°8% above, but the distribution in the circumferential direction is ±1.5% in film thickness distribution, and the population The lattice spacing was 1°4% above. Further, Δd/d (dispersion among 50 layers) at one position was 2°1%. On the other hand, as Example 2, the substrate rotation speed is 18
rpmSRAffi,=9,R,7,=9,N,...
= 50, the other conditions were the same as in Example 1, and (16 C films + 24 W films) X
A C/W multilayer film with a thickness of 50@ was created. The film thickness distribution in the radial direction and the distribution of the artificial lattice plane spacing are the same as in Example 1, with the upper 0°8.
%, 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 above 0°5%, Δd
/d was extremely good at 0.7%. In this way C
When forming a single layer of a film or a W film, by rotating the substrate multiple times to reduce statistical errors due to uneven rotation, it is possible to reduce variations in the periodic stacking of each layer.

In addition, although the above-mentioned example illustrated a multilayer thin film manufacturing method in which a plurality of target materials are alternately coated on a substrate by sputtering, these multiple target materials can be produced by electron beam heating, high frequency heating, or resistance heating melting method without using sputtering. The materials may be deposited and alternately coated on the substrate.

<Effects of the Invention> As explained above, in a method of alternately stacking particles sputtered from two or more targets on a substrate while rotating the substrate, the opening/closing operation of the shutter is adjusted to the set number of times of the substrate. Since they are synchronized, there is an advantage that the thickness unevenness of each layer due to uneven rotation can be reduced. 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
By the combinations of i, Nb and AI, Nb and Sn, and Nb and Ge, it is possible to form them alternately in an artificial lattice shape according to the periodic length of the A15 structure exhibiting superconductivity.

For example, for Nb and Si, the substrate temperature is 600°C to 300°C.
When Nb and Si were laminated by 2 to 3 people each in the range of , the formation of A15 phase was confirmed from XIj1 diffraction. Therefore, the present invention is advantageous in producing artificial lattice films having extremely high precision periodicity and thermally non-equilibrium structural films.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the multilayer thin film manufacturing apparatus according to the present invention, FIG. 2 is a schematic configuration diagram of the control section of FIG.
Fig. 4 is a schematic configuration diagram of an apparatus used in a conventional method for producing a multilayer thin film, and Figs. 5(a) and 5(b) are a cross-sectional view and a top view, respectively, of the apparatus used in another conventional method for producing a multilayer thin film. , FIG. 6 is a flowchart of the operating sequence of the apparatus of FIG. 5. In the figure, 1...Substrate for thin film formation, 2...Substrate holder electrode, 3.4...Cathode electrode, A, B...Targets (made of different substances), 6.7. ...Shutter, 8...Rotation detection sensor, 9...Motor, 10...Rotation detection counter, 11...Rotation speed detector, 12...Control unit, 20...Multilayer thin film forming device

Claims (4)

[Claims] (1) A voltage is applied to the substrate holder electrode and an electrode having multiple targets made of different materials to cause sputter discharge, and the substrate holder electrode with the substrate attached is rotated at a constant rotational speed, and each of the above targets is placed on the substrate. In a method for manufacturing a multilayer thin film in which sputtered films of target materials are sequentially and alternately deposited at a constant period, when each sputtered layer of each target material is deposited, the substrate holder electrode is rotated at a constant rotational speed. a step of opening a sputtering path for a target material, forming a sputtered layer of the target material to a predetermined thickness by passing the substrate over the sputtering path a predetermined number of times, and then closing the sputtering path for the target material; Subsequently, after opening the sputtering path for another target material, the substrate holder electrode is passed over the sputtering path of the target material to deposit the target material to a predetermined thickness, and then the sputtering path is opened. 1. A method for producing a multilayer thin film, characterized in that sputtered layers of each target material are alternately stacked by repeating the step of closing. (2) Each target material is sequentially and alternately laminated at a constant period through a radial sputtered film thickness uniformity film thickness correction plate disposed between the target and the substrate holder electrode. The method for producing a multilayer thin film according to item (1). (3) Claim (2) characterized in that the film thickness correcting plate is a plate having a fan-shaped opening having a small diameter in the direction of the rotation axis of the substrate holder electrode and a large diameter in the circumferential direction. A method for manufacturing the multilayer thin film described. (4) a power source that supplies sputter discharge power to a substrate holder electrode plate and a cathode electrode having a plurality of targets made of mutually different materials arranged on the substrate holder side of the substrate holder electrode plate facing the substrate; A drive source that rotates the substrate holder electrode plate around its central axis, a rotation detection sensor that detects the number of rotations and rotation speed of the substrate holder electrode plate, and a plurality of cathode electrodes having the target between the substrate holder electrode plate and the target. A shutter means is provided, and opens and closes a sputter evaporation path for the target material, and opens and closes the shutter means and discharges power to the cathode electrode in accordance with the rotation number and rotation speed of the substrate holder electrode detected by the rotation detection sensor. and a controller for adjusting drive power to the drive source.