JP2002124471A - Film forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool a substrate in a rotation/revolution film forming device. SOLUTION: A vacuum chamber is provided with a holder 18 which can freely rotate with a revolution axis 34 as the center, a substrate holder 20 which is held by the holder at the periphery of the revolution axis and which can freely rotate with a rotation axis 40 as the center, a rotation driving part 22 for rotation-driving the holder and the substrate holder, and a cooling part 24 for cooling a substrate to be processed 42 which is held by the substrate holder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming apparatus for performing a film forming process on a substrate to be processed in a vacuum.

[0002]

2. Description of the Related Art In recent years, SAW (Surface), which is an electronic component for mobile communication equipment used in a transmitting / receiving circuit of a portable terminal,
The demand for Acoustic Wave (surface acoustic wave) filters is increasing dramatically as a key device for wireless communication devices.

[0003] To manufacture this SAW filter, a sputtering apparatus using plasma is used. Hereinafter, the operating principle of the SAW filter and the film forming characteristics required at the time of manufacturing the SAW filter will be described with reference to FIG. FIG. 4 is a perspective view showing a configuration of a typical SAW filter.

As shown in FIG. 4, the SAW filter includes a piezoelectric substrate 10 and comb electrodes 12a and 12b. The piezoelectric substrate 10 is a ferroelectric substrate having a so-called piezoelectric characteristic that generates distortion when an electric field is applied to a substance. For example, LTO (lithium tantalum oxide; LiTaO ₃ ) is used as the piezoelectric substrate 10. On the upper surface of the piezoelectric substrate 10, comb-shaped electrodes 12a and 12b made of a material such as Al or AlCu are provided. When a high-frequency voltage is applied to the comb-shaped electrode 12a on the input side, distortion occurs on the surface of the substrate 10 with which the electrode 12a contacts, and a surface acoustic wave 14 is generated. This surface acoustic wave 1
Numeral 4 propagates on the surface of the piezoelectric substrate 10 and is output as a voltage by the comb-shaped electrode 12b on the output side. Since the frequency of the propagated surface wave is determined according to the shapes of the comb-shaped electrodes on the input side and the output side, such a structure functions as a filter.

[0005] As described above, the frequency of the surface acoustic wave is determined by the thickness of the comb-shaped electrode and its pattern shape. Therefore, the electrode thickness uniformity is an important factor.

Conventionally, as a film forming apparatus for uniformly forming a film thickness, a sputtering apparatus provided with a self-revolving substrate holder disclosed in Document 1 (Japanese Patent Laid-Open No. 6-256940) (hereinafter referred to as a self-revolving type). A film forming apparatus is known.

[0007]

However, the conventional revolving film forming apparatus cannot provide means for cooling the substrate due to its mechanical complexity. Therefore, there is a problem that the temperature in the film formation chamber and the substrate during the film formation is inevitably increased, and an impurity gas is generated. When a heating source is installed near the rotating mechanism,
For example, there have been many troubles of the rotating mechanism itself such as a failure of the rotating motion due to the deformation of the bearing and a decrease in the lubricating function due to the depletion of the lubricant.

Further, with the recent increase in the frequency, it has become necessary to reduce the electrode width of the comb-shaped electrode of the SAW filter. Previously, pure Al was mainly used as an electrode material. However, pure Al is liable to cause electromigration or vibration-induced stress migration caused by vibrations in which Al atoms exposed to a high temperature are directly exchanged with kinetic energy from electrons carrying a direct current, and may cause disconnection of electrodes. is there.

On the other hand, it is known that the addition of impurities to pure Al reduces the above-mentioned electromigration and stress migration. Therefore, as a comb-shaped electrode material, for example, AlCu to which a trace amount of Cu is added is used.

However, it is known that the solubility of Cu in Al has a very high temperature dependency, and the solubility increases as the substrate temperature increases. FIG. 5 shows the relationship between the solubility of various elements in Al and the temperature (Source: Metal Handbook)
3rd revised edition, edited by The Japan Institute of Metals, published by Maruzen Co., Ltd.). FIG.
As shown in the figure, the solubility of Cu in Al at room temperature is very low, and hardly dissolves at room temperature (1000 / T ≒ 3.3). This means that Cu atoms do not enter the Al grains but exist around the grains, that is, in a state where they are gathered at the boundary portion. However, when the substrate temperature rises, the Cu in the boundary portion is dissolved in the Al grains, and an alloy of Al and Cu is formed. The details have not been elucidated yet, but are generally considered as described above.

It is said that when an AlCu film is deposited on a substrate by a sputtering method using plasma discharge, the temperature of the substrate becomes several hundred degrees due to radiant heat from the target or impact by accelerated secondary electrons emitted from the target. . As a result, Cu that hardly dissolves at room temperature becomes 10 ⁻⁴ at% to 10 ⁻³ at% in Al.
Becomes soluble. At this time, if there is a temperature unevenness of about 10% in the substrate temperature, it can be seen from FIG. 5 that the Cu solubility differs several times. Since the electric resistance of Cu is smaller than that of Al, electricity easily flows through Cu. Therefore, depending on the amount of Cu present at the grain boundary, AlCu
A change occurs in the sheet resistance value of the entire film. That is,
The occurrence of the substrate temperature distribution makes it difficult to reduce the distribution of the resistivity ρ of the AlCu film to 0.5% or less.

Therefore, in the conventional self-revolution type film forming apparatus in which the substrate cannot be cooled, there is a problem that the electric characteristics of the film formed become non-uniform.

The LTO substrate, which is a ferroelectric substance, has a piezoelectric effect as described above, and also has a pyroelectric effect. The pyroelectric effect is a phenomenon in which spontaneous polarization increases as the temperature rises. Although the pyroelectric coefficient of LTO is not so large, it is 200 (10 ⁻⁶ Cm ⁻² K ⁻¹ ), and a voltage is generated by an increase in polarization due to an increase in temperature. Due to this property, in the conventional self-revolution type film forming apparatus which could not be water-cooled, the substrate was stuck to the substrate holder due to the temperature rise of the substrate during the deposition of the AlCu film, and there was a problem in transporting the substrate.

[0014] To solve this problem, a method of reducing the sputtering power is also conceivable. However, this method means that the deposition rate is reduced, resulting in an increase in the mixing ratio of the impurity gas during the deposition. It is known that the specific resistance of the deposited film is lower as the amount of impurity gas remaining in the vacuum processing chamber is smaller. Therefore, an increase in the impurity gas leads to an increase in the specific resistance ρ, that is, a decrease in the film quality of the AlCu film,
Not recommended.

In the space between the substrate and the target,
There is also a method of arranging a cooled shield material to prevent radiant heat incident from the target. However, this method has a problem in that dust (separation of the deposited film) generated from the shielding material near the substrate falls on the substrate.

As described above, in the conventional self-revolving film forming apparatus, the substrate cannot be cooled, so that an increase in the substrate temperature cannot be avoided. As a result, non-uniformity of the specific resistance distribution of the AlCu film, deterioration of the film quality, and inconvenience of substrate transfer occur.

[0017]

According to the present invention, there is provided a film forming apparatus for performing a film forming process on a substrate to be processed held in a vacuum chamber, wherein the apparatus rotates in a vacuum chamber about a revolution axis. A free holder holder, a substrate holder held around the revolving axis by the holder holder, and rotatable about the rotation axis, a rotation driver for rotating the holder holder and the substrate holder, and a substrate holder And a cooling unit for cooling the substrate to be processed held by the device.

According to this structure, the substrate to be processed held by the self-revolving substrate holder can be cooled, so that a film having excellent film quality can be formed with good productivity.

In the film forming apparatus of the present invention, preferably, the cooling section is provided inside the holder holding section and the substrate holder, and is constituted by a flow path for circulating a cooling medium.

Further, the above-mentioned flow path is provided in the first holder in the substrate holder.
Flow path, a second flow path connected to the first flow path and disposed along the rotation axis, a refrigerant introduction part which is a part for introducing and discharging the cooling medium, and a refrigerant introduction part Connected to
A third flow path arranged along the orbital axis; and a fourth flow path connecting the second flow path and the third flow path.
The fourth flow path and the fourth flow path, and the third flow path and the refrigerant introduction part are preferably connected via a rotation introduction mechanism.

Further, in the film forming apparatus of the present invention, preferably, the first tube constituting the holder holding portion is provided rotatably about the revolving shaft with respect to the vacuum chamber via a sealing mechanism. The second tube constituting the substrate holder is preferably provided rotatably around the rotation axis with respect to the holder holding portion via a sealing mechanism.

Further, the above-mentioned sealing mechanism is preferably a magnetic fluid seal.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the drawings are nothing but schematic representations of shapes, sizes and arrangements so that the present invention can be understood. Therefore, the present invention is not limited to the illustrated example.

FIG. 1 is a cross-sectional view showing a main configuration of a film forming apparatus according to an embodiment. In the drawings, hatching indicating a cross section is partially omitted. FIG. 2 is a perspective view showing an arrangement relationship between the substrate holder and the holder holding unit.

The film forming apparatus of this embodiment is a sputtering apparatus for forming a film on a substrate to be processed held in a vacuum chamber. The vacuum chamber is defined by a vacuum chamber (not shown) above the base plate 16 in FIG. In this vacuum chamber, a holder holder 18 and a substrate holder 20
, A rotation drive unit 22 and a cooling unit 24.

The holder holding section 18 includes a tubular member (first tube) 26 and a storage chamber 28. The tubular member 26 is arranged so as to pass through the opening 16 a of the base plate 16. The tubular member 26 is attached to a vacuum chamber, that is, the base plate 16 via a seal mechanism 30. Since the bearing 32 is inserted between the sealing mechanism 30 and the tubular member 26, the tubular member 26
It is freely rotatable about a center revolution shaft 34. The storage chamber 28 is connected to an end of the tubular member 26 on the vacuum chamber side. The inside of the storage chamber 28 becomes the atmosphere.

The substrate holder 20 is a tubular member (second tube)
20a and a disc-shaped member 20b. The tubular member 20a is disposed so as to pass through an opening formed on a surface of the storage chamber 28 opposite to the tubular member 26.
The tubular member 20a is attached to a holder holding portion, that is, the storage chamber 28 via a seal mechanism 36. Since the bearing 38 is inserted between the seal mechanism 36 and the tubular member 20a, the tubular member 20a is rotatable about the rotation shaft 40 in FIG. The rotation axis 40 is
It is parallel to the revolution axis 34. Thus, the substrate holder 20
Is held around the revolution shaft 34 by the holder holding portion 18 and is rotatable about the rotation shaft 40. A disk-shaped member 20b is connected to an end of the tubular member 20a outside the storage chamber 28, and a substrate 42 to be processed such as a wafer is mounted on the member 20b.

As shown in FIG. 2, in this embodiment,
Four substrate holders 20 are arranged around the revolution shaft 34. The rotation shafts 40 of the respective substrate holders 20 are respectively separated from the revolution shaft 34 by an equal distance, and are arranged at 90 ° intervals around the revolution shaft 34.

The number of substrate holders 20 is not limited to four, but may be, for example, five. Japanese Patent Application No. 2000-65428 filed by the assignee of the present application shows an example in which a geometric condition such as a size and an arrangement relationship is optimized in a self-revolving sputtering apparatus having five substrate holders. According to this apparatus, the in-plane film thickness distribution on the substrate is set to ± 0.1.
It can be 5% or less.

Further, the above-described sealing mechanisms 30 and 36
It is preferable to use a magnetic fluid seal.

The above-described rotation drive unit 22 includes a rotation motor 22
And a transmission system including the following elements. The rotation motor 22 is attached to a motor support 44. The driving force of the rotation motor 22 is transmitted to a pulley 48 via a rotation transmission coupler 46. Pulley 4
8 is rotated by a pulley 52 connected to a tubular member 26 forming a holder holding portion by a toothed belt 50.
Is transmitted to When the pulley 52 rotates, the tubular member 2
Numeral 6 performs a rotational movement about the revolving shaft 34. In response, the storage chamber 28 revolves. On the other hand, a planetary gear 54 is attached to the tubular member 20a constituting the substrate holder. The planet gear 54 meshes with a fixed gear 56 that is annularly arranged around the storage chamber 28. The fixed gear 56 is fixed to the base plate 16 of the vacuum chamber.

Therefore, when the storage chamber 28 revolves,
The planetary gear 54 revolves along the fixed gear 56, and at this time, the teeth of the planetary gear 54 mesh with the teeth of the fixed gear 56, so that the planetary gear 54 rotates. Since the rotation center of the planetary gear 54 coincides with the rotation axis 40, the planetary gear 5
The substrate holder 20 rotates according to the rotation of the substrate holder 4. As shown in FIG. 2, when the storage chamber 28 rotates clockwise,
The substrate holder 20 rotates counterclockwise.

FIG. 3 is a diagram showing an arrangement relationship between a substrate to be processed and a target. The vacuum chamber 76 includes a gas introduction system 78 and a gas exhaust system 80. In this vacuum chamber 76, a target 72, a substrate to be processed 42, and a holder holding section 18 are arranged. Target 72
Is provided on a cathode 74 provided on the revolving shaft 34 so as to face the substrate 42 to be processed. Each substrate 42
As described above, while performing the rotation motion, the orbit revolves as the holder holding portion 18 rotates. According to this method, an extremely uniform film thickness distribution can be obtained.

Next, the cooling unit 24 will be described.
The cooling unit 24 is for cooling the processing target substrate 42 held by the substrate holder 20. The cooling unit 24 is provided inside the holder holding unit 18 and the substrate holder 20, and is configured by a flow path for circulating a cooling medium.

The above-described flow paths include first, second, third, and fourth flow paths 58, 60, 62, and 64,
6.

The first flow path 58 is provided in the substrate holder 20. Specifically, the first flow path 58 is formed using a partition plate or the like in the internal space of the disk-shaped member 20b on which the substrate to be processed 42 is mounted, and the cooling medium spreads over the whole without stagnation. It is devised as follows.

The second flow path 60 is connected to the first flow path 58 and is provided along the rotation axis 40. Therefore, the second flow path 60 is provided inside the tubular member 20a constituting the substrate holder.

The refrigerant introduction section 66 is a section for introducing and discharging a cooling medium. The refrigerant introduction part 66 is connected to the end of the pulley 52 on the side opposite to the holder holding part 18. However, the refrigerant introduction section 66 does not rotate with the rotation of the pulley 52. The refrigerant inlet 66 includes a refrigerant inlet 66a and a refrigerant outlet 66b.
It has.

The third flow path 62 is connected to the refrigerant introduction part 66 and is disposed along the revolution axis 34. The third flow path 62 is provided inside the pulley 52 and the tubular member 26.

The fourth flow path 64 is provided between the second flow path 60 and the third flow path 64.
This is a flow path connecting the flow path 62 of FIG. The fourth flow path 64 and the third flow path 62 are connected by a connection jig 70. The fourth flow path 64 and the second flow path 60 are connected via a rotation introducing mechanism 68 described later. 4th
Is disposed in the storage chamber 28 so as to extend in a direction orthogonal to the revolution axis 34 and the rotation axis 40. In this embodiment, since four substrate holders 20 are provided, the fourth flow paths 64 are arranged radially from the connection jig 70 toward each of the substrate holders 20.

The second flow path 60 and the fourth flow path 64 are connected via a rotation introducing mechanism 68. The rotation introducing mechanism 68 can be configured using a normal O-ring or the like. According to this configuration, even while the rotation movement of the substrate holder 20 and the rotation movement of the holder holding part 18 are being performed, the second flow path 60 and the fourth flow path 64
And the cooling medium can be exchanged between them.

Similarly, the third flow path 62 and the refrigerant introduction section 66
Are connected via a rotation introduction mechanism (internal to the refrigerant introduction section 66). With this rotation introducing mechanism, the cooling medium can flow between the third flow path 62 and the refrigerant introduction part 66 even while the rotation of the holder holding part 18 is being performed.

The above second, third and fourth flow paths 60,
62 and 64 are constituted by, for example, stainless steel pipes. These flow paths are provided in two systems for introduction and discharge. The cooling medium introduced into the refrigerant introduction port 66a of the refrigerant introduction part 66 passes through the pipe for introduction, flows in the order of the third flow path 62, the fourth flow path 64, and the second flow path 60, and flows through the second flow path 60. The first flow path 58 is reached. Subsequently, the cooling medium is discharged from the first flow path 58 to a discharge pipe, and the second flow path 6 is discharged.
The refrigerant flows in the order of 0, the fourth flow path 64, and the third flow path 62, and is discharged to the outside from the refrigerant discharge port 66b. First flow path 58
, Heat exchange is performed between the cooling medium and the processing target substrate 42, and the processing target substrate 42 is cooled.

In this embodiment, the material of the substrate holder 20 is made of Al which is light and has good thermal conductivity. Substrate 4
2 is mounted on the substrate holder 20 with good adhesion by a substrate mounting jig (not shown) or an electrostatic suction method. Since the substrate holder 20 is sufficiently cooled by the cooling medium, the substrate 42 is also cooled. Normally, when an AlCu film is deposited for 6 minutes without cooling, the substrate temperature will be about one hundred degrees. On the other hand, in the device of this embodiment, when water as a refrigerant flows at 1 liter per minute,
The substrate temperature is suppressed to about 50 degrees.

As a cooling medium, florinate may be used in addition to water.

The apparatus configuration of this embodiment can be applied to various film forming apparatuses such as a magnetron sputtering apparatus, an ion beam sputtering apparatus, an electron beam sputtering apparatus, and a vapor deposition apparatus.

As described above, the number of substrate holders can be changed depending on the process and the structure of the apparatus. Furthermore, the size can be changed to an arbitrary substrate size.

[0048]

According to the film forming apparatus of the present invention, the substrate to be processed held by the self-revolving substrate holder can be cooled, so that the pyroelectric effect of the piezoelectric body does not occur, and the film forming efficiency can be reduced. Can be greatly improved. Therefore, a film having excellent film quality can be formed with good productivity.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main configuration of a film forming apparatus according to an embodiment.

FIG. 2 is a diagram showing an arrangement relationship between a substrate holder and a holder holding unit.

FIG. 3 is a diagram showing an arrangement relationship between a substrate to be processed and a target.

FIG. 4 is a diagram showing a configuration of a typical SAW filter.

FIG. 5 is a diagram showing a relationship between solubility of various elements in Al and temperature.

[Explanation of symbols]

 10: Piezoelectric substrate 12a, 12b: Comb-shaped electrode 14: Surface acoustic wave 16: Base plate 18: Holder holder 20: Substrate holder 20a: Tubular member 20b: Disc-shaped member 22: Rotary drive unit (Rotary motor) 24 : Cooling unit 26: Tubular member 28: Storage chamber 16 a: Opening 30, 36: Seal mechanism 32, 38: Bearing 34: Revolving shaft 40: Rotating shaft 42: Substrate to be processed 44: Motor support base 46: Rotation transmission coupler 48 , 52: pulley 50: toothed belt 54: planetary gear 56: fixed gear 58: first flow path 60: second flow path 62: third flow path 64: fourth flow path 66: refrigerant introduction part 66a: Refrigerant introduction port 66b: Refrigerant discharge port 68: Rotation introduction mechanism 70: Connection jig 72: Target 74: Cathode 76: Vacuum chamber 78: Gas introduction system 80: Gas exhaust system

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 22, 2001 (2001.3.2)
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0025

[Correction method] Change

[Correction contents]

The film forming apparatus of this embodiment is a sputtering apparatus for forming a film on a substrate to be processed held in a vacuum chamber. The vacuum chamber is defined by a vacuum chamber (not shown) above the base plate 16 in FIG. In this vacuum chamber, a holder holder 18 and a substrate holder 20
, A rotation introducing mechanism 68 and a cooling unit 24.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction contents]

The rotation drive unit 22 uses the rotation motor 22 as a drive source and includes a transmission system including the following elements.
The rotation motor 22 is attached to a motor support 44. The driving force of the rotation motor 22 is controlled by the rotation transmission coupler 46.
To the pulley 48 via the The rotational movement of the pulley 48 is transmitted by the toothed belt 50 to the pulley 52 connected to the tubular member 26 constituting the holder holding portion. When the pulley 52 rotates, the tubular member 26 performs a rotational movement about the revolution shaft 34. In response, the storage chamber 28 revolves. On the other hand, a planetary gear 54 is attached to the tubular member 20a constituting the substrate holder.
The planet gear 54 meshes with a fixed gear 56 arranged annularly around the storage chamber 28. This fixed gear 5
6 is fixed to the base plate 16 of the vacuum chamber.

Claims (5)

[Claims] An apparatus for performing a film forming process on a substrate to be processed held in a vacuum chamber, wherein a holder holding section rotatable around a revolving shaft is provided in the vacuum chamber, and the revolving shaft is rotated by the holder holding section. Is held around
A substrate holder rotatable around a rotation axis; a rotation drive unit for rotationally driving the holder holding unit and the substrate holder; and a cooling unit for cooling a substrate to be processed held by the substrate holder. A film forming apparatus characterized by the above-mentioned. 2. The film forming apparatus according to claim 1, wherein the cooling unit is provided inside the holder holding unit and the substrate holder, and includes a flow path for circulating a cooling medium. Characteristic film forming apparatus. 3. The film forming apparatus according to claim 2, wherein the flow path includes a first flow path in the substrate holder and the first flow path.
And a second channel disposed along the rotation axis.
A cooling medium introduction part which is a part where the introduction and discharge of the cooling medium is performed; a third flow path connected to the cooling medium introduction part and disposed along the revolution axis; , And a fourth flow path connecting the third flow path, the second flow path and the fourth flow path, and the third flow path and the refrigerant introduction unit. Are connected via a rotation introducing mechanism. 4. The film forming apparatus according to claim 1, wherein a first tube constituting the holder holding portion is rotatably provided around the revolving shaft with respect to the vacuum chamber via a sealing mechanism. And a second tube constituting the substrate holder is rotatably provided on the holder holding portion via a seal mechanism around the rotation axis. 5. The film forming apparatus according to claim 4, wherein the sealing mechanism is a magnetic fluid seal.