JPH06104896B2 - Method for producing multilayer thin film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a multilayer thin film by a sputtering vapor deposition method, and in particular, a multilayer substrate having a uniform thickness of each layer over a large area by rotating a vapor deposition substrate. The present invention relates to a method for producing a thin film.

[Prior Art] Conventionally, application of a multi-layered thin film in various fields has been studied. In many cases, in such applications, it is necessary to produce a multilayer thin film in which each layer has a uniform thickness over a large area. However, in the region where the thickness of each layer is uniform within ± 10% so far, the area about 1/10 of the target diameter is the maximum when the deposition substrate is placed right above the target.

As shown in FIG. 1, a conventional method for producing a multi-layered thin film by the sputtering deposition method comprises sputtering two or more sputtering targets having different components, and depositing each of the deposition substrates for a predetermined time. In many cases, a method was used in which the particles were moved to the front or side of the target for vapor deposition and the sputtered particles were sequentially deposited on the deposition substrate (for example, CMFalco & IKSchulle.
r: Synthetic Modulated Structures, ed.by LLChang
& BCGiessen, Accademic Press, Inc.Orland, USA
(1985), Chapter.9, pp.339-364.). Although FIG. 1 shows the case where the number of targets is two, the same applies when the number of targets is three or more. At that time, a shutter is inserted between the target and the vapor deposition substrate (2a in FIG. 1) to prevent the two components from intermingling with each other when the vapor deposition substrate moves, and the vapor deposition substrate is placed at a predetermined position on the target (normal target). (Upper part near the center of the), after moving the opening portion of the shutter (2b in FIG. 1) between the moved vapor-deposited substrate and the target to start the vapor deposition, and further for a predetermined time. After the elapse of time, the shutter is closed again to end the vapor deposition, then the substrate is moved to the next target, the same operation is performed again, the respective layers are vapor-deposited in sequence, and a multilayer film is generally produced. there were.

However, when the above shutter is used, there are the following problems. That is, the opening and closing of the shutter has a finite time peculiar to each device, and depending on the opening and closing direction of the shutter, the shutter is opened at different points on the deposition substrate for different times, and vapor deposition is performed for different times. It will be. That is, one end of the vapor deposition substrate is vapor-deposited longer, and the vapor deposition time is shorter at the opposite end. Therefore, there arises a problem that the thickness of each layer of the multilayer film is different at each point on the vapor deposition substrate. This problem becomes more serious as the thickness of one of the layers becomes thinner, the deposition rate becomes faster, and the movement of the shutter becomes slower. This state is schematically shown in FIG. That is, as described with reference to FIG. 1, when each layer A, B of the multilayer thin film is vapor-deposited, for example, if the opening 2b of the shutter 2a is moved to the left or right as shown by the arrow in the figure, if the substrate is not rotated IIIa As described above, a layer thickness distribution of each layer occurs, and as a result, the nonuniformity of the film thickness occurs (IIIb).

In order to reduce the distribution of film thickness in a single-layer film,
The method for rotating the substrate has been adopted so far.
(For example, refer to Chapter 3 of the Comprehensive Technical Data Book "Thin-Film Preparation Technology by Sputtering Method-Handling of Equipment / Measurement / Evaluation of Films and Practical Uses of Various Applications" (Management Development Center, Tokyo, 1985)).

Such non-uniformity of each layer of the multi-layer film affects various physical properties of the multi-layer film, which not only hinders an increase in area, which is indispensable for industrialization, but also affects production cost.

[Problems to be Solved by the Invention] The present invention solves these problems and has a thickness of 2 to 3
In ultra-thin multi-layer film of about Å, and also in multi-layer film including a layer having a high deposition rate of about 5 to 10 Å / s, the shutter movement is relatively slow, and the shutter opening is from one end on one target. An object of the present invention is to provide a method for producing a multilayer thin film having a uniform layer thickness even when the time required to move to one end (that is, the time required for the target to be completely opened) takes about several seconds. Is.

The present invention will be described in detail below. The non-uniformity of the layer thickness of each layer in the multilayer thin film as described above occurs, and the non-uniformity seriously affects the characteristics of the manufactured multilayer thin film in the following cases. That is, (1) the multilayer film includes a thin layer, (2) the multilayer thin film includes a layer composed of a component having a high vapor deposition rate, and (3) the shutter moves slowly. The characteristics (1) and (2) are characteristics required for producing a multilayer thin film having desired physical properties, and the characteristics (3) are extremely technically difficult to improve, especially in a large apparatus.

As for (1), for example, in quantum effect devices, which have been attracting attention in recent years, it is required to form a layer of 10 Å or less extremely uniformly. (For example, JC Bean (translated by Yasuhiro Shiraki): Semiconductor-Parity Separate Volume Series No.3 Parity Editing Committee (Edited by Hidetoshi Fukuyama) Maruzen Co., Ltd. 19
1987, Tokyo, pp.96-107). Regarding (2), in order to produce a special crystal layer having excellent physical properties peculiar to a thin film, it may be necessary to perform vapor deposition at a high speed to produce a non-equilibrium phase. Regarding (3), it is not impossible to increase the moving speed of the shutter in a small device, but in a large device for the purpose of simultaneously producing several thin films having a large area using a large target. , It is technically extremely difficult to move a huge shutter at high speed. Therefore, it was necessary to develop a method for producing a multilayer thin film having a uniform layer thickness without changing the conditions as described above.

[Means for Solving the Problems] Therefore, the present invention is configured as follows.

That is, in a method for producing a multilayer thin film by using a plurality of sputtering targets and sequentially depositing particles emitted by the sputtering from each sputtering target, in the method for producing a multilayer thin film, the rotation speed ω of the deposition substrate is ω [ rps] ≧ κV _{d, max} T / d _min (1) A method for producing a multilayer thin film, characterized in that it is rotated within a range represented by the formula:

Here, V _{d, max} [Å / s]: maximum deposition rate among the deposition rates of each layer, T [s]: required from when the shutter between the vapor deposition substrate and the target begins to open until it completely opens Time, d _min [Å]: The thickness of the thinnest of the layers constituting the multilayer thin film to be produced, κ “s ⁻¹ ”: proportional constant κ = 2.

As a method of rotation, when the vapor deposition substrate is placed in front of the target as shown in FIG. 1 for vapor deposition, it may be rotated in a plane substantially parallel to the substrate and the target with the central axis of the substrate as the central axis.

As the rotating mechanism, there are a method of arranging a vacuum motor and a battery in the chamber, and a power source may be externally supplied by a feed-through flange. In either case, the rotation shaft is driven via the gear reducer.

When the vapor deposition substrate is rotated in the range of the rotation speed by such a method, the length of the vapor deposition time depending on the location on the vapor deposition substrate caused by the movement of the shutter is eliminated, and the uniformity of the film thickness is dramatically improved.

[Operation] The operation will be described below with reference to FIG. FIG. 1 is a schematic diagram of an example of a method of rotating a vapor deposition substrate (when the substrate is placed in front of a target) when a multilayer thin film is formed by using various sputtering deposition methods (however, here, the target is Only two cases are shown, but the same is true for three or more cases). 1a and 1b are targets for sputtering. Reference numeral 2a is a shutter having an opening 2b having the same size as the diameter of one target. Reference numeral 3a is a disk for fixing a vapor deposition substrate, and 3b is a rotating mechanism for moving the disk 3a onto each target to perform vapor deposition. 4a is a jig for rotating the vapor deposition substrate, and 4b is a drive mechanism for the jig 4b. In addition, these are installed in the vacuum container O.

FIG. 2 shows how the layer thickness of each layer of the multi-layered film differs at each point on the substrate with and without the substrate rotation mechanism described in the previous section (IIIa and IVa). ) And a multilayer thin film (IIIb and IVb) formed by stacking such layers. That is, when the substrate rotation mechanism as shown above is not used, the shutter opening portion is moved above the target 1a and the target 1b, respectively, when producing a multilayer film, the shutter at a finite speed. In order to move, the opening time of the shutter seen from each position of the substrate is not uniform. As shown in IIIa, in A, the right end is longer, and in B, the left end is longer, and conversely, the opening time is longer on the opposite side. It gets shorter as you go. Therefore, the number of particles deposited at each point by opening and closing the shutter once,
That is, the layer thickness of one layer becomes thicker as the opening time becomes longer, and conversely becomes thinner as the opening time becomes shorter, so that the layer thickness distribution on the substrate as shown in IIIa occurs. As a result of such non-uniformity of the layer thicknesses at the positions on the substrate in each layer, a multilayer film having a thickness distribution as shown in IIIb is produced.

On the other hand, as shown in IVa, such non-uniformity disappears if the vapor deposition substrate is rotated at a sufficiently high speed so as to satisfy the condition expressed by the equation (1) with respect to the opening / closing time of the shutter. However, only the distribution caused by the difference in the sputtering efficiency in each part of the target remains (IVb).

In this way, the size of a multilayer thin film having a uniform layer thickness is up to the size of the target, and the larger the area, the smaller the number of particles sputtered from the target decreases. It is not possible to produce a simple multilayer film. When using a shutter, the opening area of the shutter is the upper limit.

The minimum rotation speed required to obtain a multilayer thin film having a uniform layer thickness is inversely proportional to the opening / closing speed of the shutter and the sputtering speed, that is, the vapor deposition speed. That is, the faster the opening and closing of the shutter, the slower the rotation speed, and conversely, the faster the deposition rate, the faster the rotation speed must be (see formula (1)). That is, the substrate rotation speed ω is the ratio of the vapor deposition thickness variation (V _d T) when the shutter is opened and closed to the average film thickness (d _m ) in order to make the vapor deposition time at each position of the substrate uniform (uniform film thickness). Considering the opening and closing of the shutter twice, it is better to set it to 2V _d T / d _m or more. In the case of a multilayer film, if the thickness of the thinnest one of the layers constituting the multilayer film to be produced is applied as the film thickness, and the maximum vapor deposition rate among the vapor deposition rates of the respective layers as the vapor deposition rate is applied, Certainly. In a normal large-scale sputtering vapor deposition apparatus, it takes several seconds to open and close the shutter, and the vapor deposition rate is some metal, etc., and if the input power density is about 6 W / cm ² , if it is several Å / s, In order to control the layer thickness of a multilayer thin film having a thickness of several tens of Å to about ± 10%, it is sufficient to rotate at a speed of about 5 times / s. Of course, the vapor deposition substrate may be rotated at a rotation speed higher than this, but this is meaningless and becomes technically difficult as the rotation speed increases.

[Examples] (Example 1) A multi-layered thin film of Hf / Fe was formed on a single crystal Si substrate by the method for producing a multi-layered thin film of the present invention. The production conditions are as follows.

Target: Hf (6inchΦ, 5mm thickness) and Fe (6inchΦ, 1mm)
Thickness) Sputtering gas (Ar): Flow rate, 50ccm Pressure: ~ 4 × 10 ^-3 Torr Input high frequency power: Hf: 200W, Fe: 400W Deposition substrate: Si 〈111〉 Deposition substrate temperature: Uncontrolled (100 ° C or less) Deposition time: Hf and Fe, 5 seconds each, 100 times Average time required to open and close the shutter once: Approximately 3 seconds Number of substrate rotations: 10 times / second According to the above-mentioned fabrication conditions, the parameters of equation (1) are used. Are T = 3s, d _min = 50Å and V _{d, max} = 5Å / s, respectively, suggesting that a rotation speed of ω ≧ 0.6 is sufficient to obtain a multilayer thin film with a desired layer thickness. To be done. Actually, as shown in FIG. 3, the layer thickness of each layer of the produced multi-layer thin film is larger when the substrate is rotated than when the substrate is not rotated.
The thickness of one layer is about -5% in the area of 3 cmΦ from the center and about -10% in the area of 6 cmΦ compared to the thickness of the vicinity of the center of the vapor deposition substrate whose center is fixed on the center axis of the target. The sex is maintained. On the other hand, the layer thickness of the multi-layer thin film produced without rotating the substrate under the same conditions is asymmetric in the direction of shutter movement, as shown in FIG. 3, and there is a difference between the center and 3 cmΦ. There is a difference of about ± 50% in the layer thickness. (Note that FIG. 3 shows only the Fe layer out of the distribution of the thickness of each layer.) (Example 2) A W / C multilayer thin film was produced on a quartz substrate by the method for producing a multilayer thin film of the present invention. . The production conditions are as follows.

Target: W (6inchΦ, 5mm thickness) and C (6inchΦ, 5mm)
Thickness) Sputtering gas (Ar): Flow rate, 50ccm Pressure: ~ 4 × 10 ^-3 Torr Input high frequency power: W: 200W, C: 400W Deposition substrate: Quartz glass (3inchΦ) Deposition substrate temperature: Uncontrolled (100 ° C or less) ) Deposition time: W and C, each 5 seconds x 100 times Average time required to open and close the shutter once: Approximately 3 seconds Substrate rotation: 2 times / second According to the above manufacturing conditions, The parameters are T = 3s, d _min = 10Å and V _{d, max} = 1Å / s, respectively, and a rotation speed of ω ≧ 0.6 is sufficient to obtain a multilayer thin film with a desired layer thickness. It is suggested. In fact, the layer thickness of each layer of the multilayer thin film produced under the above-described production conditions is one layer fixed at the center on the center axis of the target when the substrate is rotated, compared to when the substrate is not rotated. Uniformity of the layer thickness of about -5% is maintained in the region of 4 cmΦ and about -10% in the region of 7 cmΦ compared to the thickness near the center of the deposited substrate. On the other hand, the layer thickness of the multilayer thin film produced without rotating the substrate under the same conditions is also asymmetrical in the direction of shutter movement, and the layer thickness is around ± 50% between the center and 4 cmΦ. There is a difference.

Both W and C have slow deposition substrates (several tens of Å / s),
It was found that the substrate rotation speed was sufficient at this level.

(Comparative Example 1) An Hf / Fe multilayer thin film was formed on a single crystal Si substrate by the method for producing a multilayer thin film of the present invention. The production conditions are as follows.

Target: Hf (6inchΦ, 5mm thickness) and Fe (6inchΦ, 1mm)
Thickness) Sputtering gas (Ar): Flow rate, 50ccm Pressure: ~ 4 × 10 ^-3 Torr Input high frequency power: Hf: 200W, Fe: 400W Deposition substrate: Si 〈111〉 Deposition substrate temperature: Uncontrolled (100 ° C or less) Deposition time: Hf and Fe, 1 second each for 100 times Average time required to open and close the shutter once: Approximately 3 seconds Number of substrate rotations: 1 time / second Are T = 3 s, d _min = 10 Å and V _{d, max} = 5 Å / s, respectively, and a rotation speed of ω ≧ 3 is necessary to obtain a multilayer thin film having a desired uniform layer thickness. The thickness of each layer of the produced multilayer thin film is about -10% in the region of 3 cmΦ from the center, 6 cmΦ, compared with the thickness of the layer near the center of the vapor deposition substrate whose center is fixed on the center axis of the target. In this area, the layer thickness is about -20%. This is inferior in the uniformity of the layer thickness as compared with the case where the substrate rotation speed is 10 times / second shown in the first embodiment. This is because the rotation number of the substrate (1 turn / second) in this comparative example does not satisfy the rotation condition ω ≧ 3 for obtaining sufficient uniformity of the layer thickness and is too small.

EFFECTS OF THE INVENTION The present invention uses a plurality of sputtering targets, moves a deposition substrate to the front or side of the sputtering targets, and sequentially deposits particles emitted by the sputtering from the sputtering targets to obtain a multilayer structure. Among the sputtering deposition methods for producing thin films, the target diameter is the area where the thickness of each layer of the multilayer thin film can be controlled within ± 10% compared to the case where the evaporation substrate is rotated about its center as an axis of rotation and is not rotated. It is a method to expand to about 1/2. By this method, it becomes possible to fabricate a multi-layered thin film in which each layer has a uniform layer thickness over a large area, which is extremely useful for various applications of the multi-layered thin film.

[Brief description of drawings]

Fig. 1 is a schematic diagram of this device, Fig. 2 is a schematic diagram of this method, and Fig. 3 is how the layer thickness distribution of one layer of the Fe layer in the vapor-deposited multilayer thin film differs depending on the presence or absence of substrate rotation. Is shown. 1a, 1b ... Target for spattering, 2a ... Shutter, 2b ... Shutter opening, 3a ... Disk for fixing and moving vapor deposition substrate, 3b ... Rotating mechanism of disk, 4a ... Vapor deposition substrate holder, 4b …… Rotation mechanism of vapor deposition substrate holder, 5a, 5b
...... Vapor-deposited thin film, A, B ... Components of each layer, O ... Vacuum container that houses this device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-58-110671 (JP, A) JP-A-63-50466 (JP, A) JP-B-51-14993 (JP, B2)

Claims (1)

[Claims] 1. A method for producing a multilayer thin film by using a plurality of sputtering targets and depositing particles emitted by the sputtering from the respective sputtering targets in order, wherein a deposition substrate is rotated at a rotation speed ω. Ω [rps] ≧ κV _{d, max} T / d _min (where V _{d, max} [Å / s]: maximum deposition rate among the deposition rates of each layer, T [s]: deposition substrate and target shutter begun open time required to end completely opened from between, d _min [Å]: among the respective layers constituting the multilayer film to be produced, the most thick layer of thin thickness, kappa "s ^{- 1} ": proportional constant κ = 2) A method for producing a multilayer thin film, which comprises rotating the film within a range represented by the formula: