JP2008179861A - Magnetron sputtering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetron sputtering apparatus which can uniformly form a sputtered film on a substrate. <P>SOLUTION: The magnetron sputtering apparatus forms the sputtered film on the substrate 13 by generating plasma and making a target 5 emit sputtered particles, wherein a jig 10 for making the film uniformly formed on the substrate 13 has a curved surface shape expressed by Y<SP>2</SP>=-X<SP>2</SP>-a<SP>2</SP>+2K<SB>0</SB>±2(a<SP>2</SP>X<SP>2</SP>+K<SB>0</SB><SP>2</SP>-K<SB>0</SB>a<SP>2</SP>)<SP>1/2</SP>and K<SB>0</SB>=[(a<SP>2</SP>+d<SP>2</SP>)/2d]<SP>2</SP>, or a polygonal shape similar to the curved surface shape, when the axis passing through the centers of the jig 10 and the target-holding part 6 is defined as a Y-axis, the axis perpendicular to the Y-axis in the horizontal plane of the target 5 is defined as an X-axis, the coordinate of a point at which the center of the jig 10 intersects with the Y-axis is defined as (0, d), the coordinate of the center of the target 5 is defined as (0, 0), and the coordinates of eroding parts 12 to be formed on the target 5 are defined as (a, 0) and (-a, 0). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetron sputtering apparatus for forming a sputtered film having a uniform thickness on a substrate.

In the sputtering method, when the target is sputtered, it is required to uniformly form the sputtered particles protruding from the target on the substrate and to improve the utilization efficiency of the target, so various proposals have been made.
Patent Document 1 describes the following magnetron sputtering apparatus.
The magnetron sputtering apparatus described in Patent Document 1 will be described with reference to FIG.
A target 101 is disposed above the yoke 100, and a substrate 102 is disposed above the target 101 so as to face the target 101. On the yoke 100, a rotating magnet 103 is arranged slightly deviated from the central portion thereof, an outer peripheral magnet 104 is arranged along the periphery thereof, and an auxiliary magnet 105 is arranged inside the outer peripheral magnet 104. Yes.
Then, by adjusting the shape of the auxiliary magnet 105, the N / S pole, etc., and changing the gradient of the line of magnetic force generated between the rotating magnet 103 and the outer peripheral magnet 104, the target 101 is sputtered. And the uniformity of the film thickness distribution in the substrate can be improved.

However, the plasma concentrates on a part of the target 101 to form an erosion region, and a considerable amount of sputtered particles are deposited on the substrate 102 from the erosion region by a scattering distribution according to the cosine law. In general, the thickness of the sputtered film formed at the center of the target is the thickest at the center of the target, and the thickness of the sputtered film becomes thinner toward the outer periphery. Further, the film thickness distribution is improved by rotating the rotating magnet 103 and the auxiliary magnet 105 to widen the erosion. However, the film thickness is said to be the thickest at the center of the target and become thinner toward the outer periphery. There was a problem that the tendency of distribution would appear.
Further, since the sputtered particles have a steep incident angle on the outer side than the center, there is a problem that the thickness of the sputtered film laminated on the substrate 102, the distribution of characteristics, and the variation become large.
As countermeasures, it has been considered to increase the distance between the target 101 and the substrate 102 and to arrange a film thickness correcting plate between the target 101 and the substrate 102.
JP-A-1-268867

  However, widening the distance between the target 101 and the substrate 102 causes a problem that production efficiency is lowered because it is necessary to lengthen the film formation time when the sputtered film is formed thick. The method of disposing a film thickness correction plate between the target 101 and the substrate 102 is effective only when the film is formed while moving the substrate 102, and cannot be used for film formation when the substrate 102 is fixed. Further, when the film is formed while moving the substrate 102, the film thickness correcting plate blocks a part of the sputtered film, which causes a problem that the film forming speed of the sputtered film is reduced.

  Therefore, the present invention has been made to solve the above-described problems, and provides a magnetron sputtering apparatus capable of uniformly forming a sputtered film on a substrate without reducing the film formation speed. For the purpose.

The present invention relates to an anode for holding a film-forming jig in a vacuum chamber, a cathode provided so as to face the anode, and a target support unit for holding a target arranged between the anode and the cathode. A permanent magnet that is provided on the side of the target support opposite to the anode and that generates a leakage magnetic field on the target surface, and a high-frequency power source that generates plasma when gas is introduced into the vacuum chamber. A magnetron sputtering apparatus arranged such that the center of the film-forming jig held by the anode and the center of the target holding part are coaxial, the center of the film-forming jig and the target holding part An axis passing through the center is a Y-axis, and an axis that is in a horizontal plane of the target and is orthogonal to the Y-axis is an X-axis. The coordinates of the point at which the center intersects the Y axis is (0, d), the center coordinates of the target are (0, 0), and the coordinates of the erosion part formed on the target are (a, 0), (-a , 0), the magnetron sputtering apparatus is characterized by having a curved surface shape represented by the following formula or a polygonal shape approximated to the curved surface shape.

According to the present invention, an axis passing through the center of the film-forming jig and the center of the target holding portion is a Y-axis, and an axis that is in the horizontal plane of the target and is orthogonal to the Y-axis is the X-axis. The coordinates of the point where the center of the jig intersects the Y axis is (0, d), the center coordinates of the target are (0, 0), and the coordinates of the erosion part formed on the target are (a, 0), ( -a, 0), it has a curved surface shape represented by the following formula or a polygonal shape approximated to the curved surface shape, so that the sputtered film is uniformly formed on the substrate without reducing the film formation rate. Can be formed.

A magnetron sputtering apparatus according to an embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is a diagram showing a magnetron sputtering apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic diagram for explaining the relationship between a substrate and a target when a flat substrate is used.
FIG. 3 is a diagram showing a state in which the sputtering film thickness obtained theoretically and experimentally obtained when a flat substrate is used coincide with each other.
FIG. 4 is a diagram showing a curved surface shape of a film forming jig for uniformly laminating the sputter film thickness when the substrate can be bent.
FIG. 5 is a diagram showing a curved surface shape of a film forming jig for uniformly stacking the sputter film thickness when the substrate cannot be bent.

  As shown in FIG. 1, a magnetron sputtering apparatus 1 according to an embodiment of the present invention has a gas pipe 3 for introducing a gas to one side 2A, and an exhaust pipe 4 for evacuating to the other side 2B. A vacuum chamber 2 having a target, a target support 6 holding a target 5 disposed in the vacuum chamber 2, a yoke-type permanent magnet 7 disposed below the target support 6, and a target support 6. A cathode 8 that connects the vacuum chamber 2, an anode 9 that is disposed above and parallel to the target support 6 and holds the film-forming jig 10, and a high-frequency power source 11 that generates plasma are provided. Yes. In addition, although this description demonstrates the case where the target 5 is a disk-shaped round shape, as a cross-sectional shape, a square target is also the same.

The yoke-type permanent magnet 7 includes a base 7A, a central magnetic pole 7B fixed to the center on the base 7A, and an annular magnet 7C formed so as to surround the central magnetic pole 7B. The center magnetic pole 7B has an S pole at the upper part and an N pole at the lower part. The annular magnet 7C has an N pole at the upper part and an S pole at the lower part. The magnetic field is directed from the annular magnet 7C toward the central magnetic pole 7B. Is formed.
One of the high-frequency power sources 11 described above is connected to the base 7A, and the other is grounded.

As shown in FIG. 2, the axis passing through the center of the film forming jig 10 and the center of the target holding unit 6 is the Y axis, and the axis that is in the horizontal plane of the target 5 and is orthogonal to the Y axis is the X axis. The coordinates of the point at which the center of 10 intersects the Y axis is (0, d), the center coordinates of the target 5 are (0, 0), and the coordinates of the erosion part formed on the target 5 are (a, 0), (- a, 0)
The curved surface shape of the film forming jig 10 is expressed as follows.

It will be described below that the curved surface shape of the film forming jig 10 is expressed by the equation (1).
First, as shown in FIG. 2, a flat substrate 13 is arranged on the anode 9 when Y = d, and the sputtering film thickness laminated on the substrate 13 when actual sputtering is performed will be described later. Comparison was made with the sputtering film thickness obtained from the simulation result (8).
Here, it is assumed that sputtering is performed only from the erosion part 12 of the target 5, and the sputtered particles sputtered from the erosion part 12 reach the substrate 13 linearly.
The coordinate axes in the XY plane are the same as described above.

The vector in the position coordinate (X, d) direction on the substrate 13 where the sputtered particles arrive from the position coordinate (a, 0) of the erosion unit 12 is the vector t ₁ , and the substrate from the position coordinate (−a, 0) of the erosion unit 12 position coordinates on 13 (X, d) the direction of the vector vector t _2, when the resultant vector of the vectors t ₁ and the vector t ₂ and vector t, expressed as follows.

Then, the position coordinate of the center of the substrate 13 is (0, d), and the position coordinate (X, d) on the substrate 13 where the sputtered particles from the position coordinate (a, 0) of the erosion part 12 reach the substrate 13 is reached. the position coordinates of the distance t _1, erosion unit 12 (-a, 0) sputtered particles from the substrate 13 to reach the substrate 13 (X, d) the distance to t _2, the position coordinates (a, 0 ) And the position coordinates (X, d) are each θ ₁ , and the line connecting the position coordinates (−a, 0) and (X, d) is each X _2. Then, the thickness t of the sputtered film formed at the position coordinate (X, d) on the substrate 13 can be expressed as follows.

  In general, sputtered particles sputtered from the position of the erosion part 12 spread radially according to the cosine law. Therefore, the thickness of the sputtered film formed on the substrate 13 is the distance between the position of the erosion part 12 and the substrate 13. Inversely proportional to

That is, when the inverse proportionality coefficient is K, t ₁ , t ₂ , sin θ ₁ , sin θ ₂ can be expressed as follows.

  Substituting Equations (4) to (7) into Equation (3) to obtain Equation (8).

On the other hand, when sputtering was performed using the magtron sputtering apparatus 1, the sputtered film laminated on the substrate 13 was measured.
At this time, the sputtering gas pressure is 3 mTorr, the power of the high-frequency power source 11 is 800 W, the target diameter is 6 inches φ, and a = 30 mm and d = 70 mm.

The result is shown in FIG.
In FIG. 3, the horizontal axis is the distance (mm) from the center of the substrate 13, and the vertical axis is the thickness variation (%) in the substrate 13 when the thickness at the center of the substrate 13 is 100%. ), The broken line is the simulation value, and the solid line is the actual measurement value.
As shown in FIG. 3, the simulation value and the actual measurement value are almost the same, and it was found that the sputtered particles follow the cosine law. As a result, it was found that sputtering was performed only from the erosion part 12 of the target 5, and it was found that the sputtered particles sputtered from the erosion part 12 may be simulated on the assumption that they reach the substrate 13 linearly. .
However, the sputtered film becomes thinner as the distance from the center of the substrate 13 increases.

Next, a description will be given of making the sputtering film thickness uniform on the substrate 13 based on the above simulation.
Here, it is assumed that the sputtered particles reach the substrate 13 in the vertical direction.
In this case, since the thickness T of the sputtered film laminated on the substrate 13 is the length of the combined vector t, the absolute value of each vector in the equation (1) is taken and can be expressed as follows.

  Next, the following equation is obtained by squaring both sides of equation (9).

Here, in the equations (4) to (7), t ₁ , t ₂ , sin θ ₁ , sin θ ₂ , cos θ ₁ , and cos θ _{2 in} which d is replaced with Y are obtained to obtain the following equations.

  Next, substituting the equations (11) to (16) into the equation (10), the following equation (17) is obtained.

Since the sputtered film laminated on the substrate 13 is constant, T = constant. Here, when (K / T) ² = K ₀ (constant), the equation (17) can be rearranged and expressed as follows.

  Next, when formula (18) is arranged so as to be a quaternary equation of Y, it can be expressed as follows.

Further, the equation (19) is modified to obtain the above-described equation (1).
Here, the thickness T of the sputtered film laminated on the substrate 13 at the position coordinate (0, d) can be expressed as follows from the equation (17).

Next, as in the case of obtaining the thickness of the sputtered film laminated on the substrate 13 in the case where the flat substrate 13 is disposed on the anode 9, a = 30 mm and d = 70 mm, and these are (1 When the curved surface shape that can make the sputter film thickness uniform is obtained by substituting it into the equation (1), it is as shown in FIG. As shown in FIG. 4, in order to make the sputter film thickness uniform, the substrate 12 is placed on a film forming jig 10 that is curved so as to approach the target 5 as it goes from the center to the periphery. It turns out that it needs to be done.
In FIG. 4, the horizontal axis represents the distance (mm) in which one side is the positive direction and the other is the negative direction with respect to the center of the target 5, and the vertical axis is the distance (mm) between the target 5 and the substrate 13. is there.

When the substrate 13 is bent like a thin sheet, the sputter film thickness is set by placing the substrate 13 on the film forming jig 10 using the film forming jig 10 having the shape shown in FIG. Can be uniform.
However, when it cannot be bent like a thick substrate, a similar effect can be obtained by using a polygonal jig approximated to the curved surface shape shown in FIG. 4 as shown in FIG. Although the figure has a single-stage polygonal shape, if the substrate size is smaller, a two-stage or three-stage polygonal shape approximating a curved surface shape can provide a uniform film thickness distribution. Can be achieved.
In FIG. 5, the horizontal axis indicates the distance (mm) in which the horizontal axis indicates one in the positive direction and the other in the negative direction with respect to the center of the target 5, and the vertical axis indicates the distance between the target 5 and the substrate 13. (Mm).

Next, the operation of the magnetron sputtering apparatus 1 will be described.
First, the substrate 13 is fixed to the film forming jig 10, while the target 5 is held on the target support portion 6.
Next, after the inside of the vacuum chamber 2 is brought to a predetermined degree of vacuum through the exhaust pipe 4 with a vacuum pump (not shown), for example, Ar gas is introduced into the vacuum chamber 2 through the gas pipe 3 to obtain a predetermined gas pressure. To.
Next, the high frequency power source 11 is driven to generate plasma by Ar gas, and the plasma is confined by a leakage magnetic field formed between the central magnetic pole 7A of the yoke-type permanent magnet 7 and the annular magnet 7B. Sputtered particles are discharged, and a sputtered film is stacked on the substrate 13.
In this way, a sputtered film having a uniform thickness can be formed on the substrate 13. Furthermore, since the film grows perpendicular to any substrate, the film characteristics become more uniform.

  As described above, according to the embodiment of the present invention, one direction in the horizontal plane of the target 5 is the X axis, the direction orthogonal to the X axis and the center of the target 5 is the Y axis, and the anode 9 The coordinates of the point intersecting the Y axis are (0, d), the center of the target 5 is (0, 0), and the coordinates of the erosion part 12 formed on the target 5 are (a, 0), (-a, 0). When using the film-forming jig 10 having a curved surface shape represented by the formula (1) or a polygonal shape approximated to the curved surface shape, the substrate 13 is placed on the film-forming jig 10 and sputtering is performed. Therefore, a sputtered film having a uniform film thickness and characteristics can be obtained. In addition, since a film thickness correction plate or the like is not provided between the target 5 and the substrate 13, the film formation speed is not reduced.

It is a figure which shows the magnetron sputtering apparatus in embodiment of this invention. It is the schematic for demonstrating the relationship between a board | substrate and a target at the time of using a flat substrate. It is a figure which shows a mode that what was calculated | required theoretically and what was calculated | required experimentally when the flat board | substrate is used are obtained. It is a figure which shows the curved surface shape of the film-forming jig | tool for uniformly laminating | stacking a sputtering film thickness, when a board | substrate can be bent. It is a figure which shows the curved surface shape of the film-forming jig | tool for uniformly laminating | stacking a sputtering film thickness when a board | substrate cannot be bent. It is the schematic which shows the conventional magnetron sputtering apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Magnetron sputtering apparatus, 2 ... Vacuum chamber, 2A, 2B ... Side part, 3 ... Gas pipe, 4 ... Exhaust pipe, 5 ... Target, 6 ... Target support part, 7 ... Yoke type permanent magnet, 7A ... Base, 7B ... center magnetic pole, 7C ... annular magnet, 8 ... cathode, 9 ... anode, 10 ... film forming jig, 11 ... high frequency power source, 12 ... erosion part, 13 ... substrate

Claims (1)

An anode for holding a film-forming jig in a vacuum chamber; a cathode provided to face the anode; a target support for holding a target placed between the anode and the cathode; and the anode A permanent magnet that generates a leakage magnetic field on the target surface, and a high-frequency power source that generates plasma when gas is introduced into the vacuum chamber. In the magnetron sputtering apparatus arranged so that the center of the film-forming jig held in the center and the center of the target holding unit are coaxial,
An axis passing through the center of the film forming jig and the center of the target holding unit is a Y axis, and an axis that is in a horizontal plane of the target and is orthogonal to the Y axis is an X axis, and the center of the film forming jig is the The coordinates of the point that intersects the Y axis are (0, d), the center coordinates of the target are (0, 0), and the coordinates of the erosion part formed on the target are (a, 0), (-a, 0). And when
The magnetron sputtering apparatus, wherein the film forming jig has a curved surface shape represented by the following formula or a polygonal shape approximate to the curved surface shape.

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