JP2003129236A - Thin film former - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a thin film in the state in which damages due to dust and abnormal plasma are suppressed. SOLUTION: A plasma confinement cylinder 113 that confines the scatter region of the ECR plasma delivered from a plasma formation chamber 102 is provided below the bottom of a target 105 (container 105a). The cylinder is made from a nonmagnetic material such as quartz or alumina. The cylinder 113 confines the scattering of a plasma stream delivered from the chamber 102 and passed through the region of the target 105 and confines the irradiation region of the plasma stream in the surface defined by the surface of a sample mount 104 within the region on the sample mount 104.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus for forming a thin film used in electronic devices such as semiconductor devices and magnetic storage devices.

[0002]

2. Description of the Related Art First, the situation of a semiconductor device will be described. A large-scale integrated circuit (LSI) formed on a silicon (Si) substrate has been made to be highly integrated by miniaturizing the elements. MOS with a structure of gate electrode / gate insulating film / semiconductor when miniaturizing devices
When the gate length of the transistor is shortened, the operation speed is improved. Improvements in integration and operating speed due to miniaturization are the driving force for LSI technology development, and research and research aiming to overcome various limitations.
Development is underway. The miniaturization can be performed by so-called scaling, and the power supply voltage and the gate voltage are also scaled.

In order to operate the MOS transistor while suppressing the gate voltage to a low level, it is necessary to provide the semiconductor with a MOS capacitance enough to generate an inversion layer. Therefore, the gate insulating film is thinned to secure the capacitance. Came. As a result, recently, the gate oxide film of the MOS transistor has become thinner (3 nm or less) so that a direct tunnel current flows. In particular, in devices such as mobile phones and mobile terminals including PDAs that require low power consumption, it is important to suppress tunneling current and power consumption.

Recently, an insulating film having a relative dielectric constant larger than that of a silicon dioxide (SiO ₂ ) film, which has been used as a gate oxide film, is used as a gate insulating film to increase the film thickness while ensuring the capacitance. Has actively researched methods for suppressing tunnel current.

Silicon oxynitride (SiO _x N _y ), alumina (Al
₂ O ₃ ), titanium dioxide (TiO ₂ ), zirconium dioxide (ZrO ₂ ), hafnium dioxide (HfO ₂ ), lanthanum dioxide (LaO ₂ ), or a binary alloy oxide,
Silicon nitride (Si ₃ N ₄ ), aluminum nitride (Al
N), titanium nitride (TiN), zirconium nitride (Zr
N), hafnium nitride (HfN), lanthanum nitride (La)
N), or a nitride of a binary alloy, is listed as a strong candidate. Further, these high dielectric materials are combined in layers to be used for the gate insulating film.

In order to use such a material as a gate insulating film, various thin film forming apparatuses and various thin film forming methods have been tried. Among them, the sputtering method is one of the promising devices and methods because it does not require high-risk gases or toxic gases and has a relatively good surface (irregularity) morphology of the deposited film. There is. As an excellent apparatus / method for obtaining a film having a stoichiometric composition in the sputtering method, an apparatus / method for supplying oxygen gas or nitrogen gas to prevent the loss of oxygen or nitrogen in the film, that is, the reaction Promising sputtering equipment and method.

In the sputtering method, there are a case where a metal is used as a target used when depositing a high dielectric constant film and a case where a compound which becomes a film to be formed is used.
Generally, metal is easier to manufacture as a target. The compound target requires a process such as sintering, and has difficulty in shaping and adjusting the composition.

As a method for improving the film quality of the sputtered film, a plasma flow created by utilizing electron cyclotron resonance (ECR) and a divergent magnetic field is applied to the substrate, and at the same time, a high frequency wave is applied between the target and the ground. A method of applying a DC high voltage and causing ions in the plasma generated by the ECR to collide with a target for sputtering to deposit a film on a substrate (hereinafter, referred to as an ECR sputtering method)
(Reference 1: Ono et al., Jpn.J.Appl.Phys.23, No.8,
L534 (1984)).

In the generally well-known magnetron sputtering method, stable plasma cannot be obtained unless the pressure is about 0.1 Pa or more, whereas in the above ECR sputtering method,
Stable ECR with gas pressure of molecular flow of about 0.01 Pa
A plasma is obtained. Further, in ECR sputtering, particles generated by ECR are applied to a target by high frequency or direct current voltage to perform sputtering, so that sputtering can be performed at low pressure.

In the ECR sputtering method, a substrate is irradiated with an ECR plasma stream and sputtered particles. Ions in the ECR plasma flow are 10 eV to several tens of e due to the divergent magnetic field.
Controlled to V energy. Further, since the plasma is generated and transported at a pressure low enough that the gas behaves as a molecular flow, the ion current density of the ions reaching the substrate can be large. Therefore, the ions of the ECR plasma flow give energy to the raw material particles that are sputtered and fly onto the substrate, and promote the binding reaction between the raw material particles and oxygen, which improves the film quality of the film deposited by the ECR sputtering method. To be done.

The ECR sputtering method is particularly characterized in that a high quality film can be formed on a substrate at a low substrate temperature close to room temperature which does not require external heating. E
How to deposit a high quality thin film by the CR sputtering method is described in, for example, Amazawa et al., Journal of Vacuum Science and Technology, Volume B17, No. 5, 222.
P. 2, 1999 (J. Vac. Sci. Techno
1. B17, No. 5.2222 (1999). ) (Reference 2).

The surface morphology of the film deposited by the ECR sputtering method is flat on the atomic scale order. Therefore, it can be said that the ECR sputtering method is a promising method for forming a high dielectric constant gate insulating film.

Further, the situation of the optical communication device and the optical device will be described. A multilayer film formed by alternately stacking dielectric films with different optical refractive indexes is a non-reflective coating on glasses and plastics such as glasses, color separation prisms for video cameras, various optical filters, and end faces of light emitting lasers. It is used for coating. In addition, as a recent situation, wide-area wavelength division multiplexing (DWD)
It has come to be applied to the production of multiplexing filters and demultiplexing filters used for M communication).

Thin films used for the multilayer film include silicon (Si), silicon hydride (SiH), silicon dioxide (SiO ₂ ), tantalum pentoxide (Ta ₂ O ₅ ), alumina (Al ₂ O ₃ ), titanium dioxide. (TiO ₂ ), zirconium dioxide (ZrO ₂ ), hafnium dioxide (HfO ₂ ),
Lanthanum dioxide (LaO ₂ ), silicon oxynitride (Si
O _x N _y), or oxides of binary alloys, silicon nitride (SiN), aluminum nitride (AlN), zirconium nitride (ZrN), hafnium nitride (HfN), lanthanum nitride (LaN), magnesium fluorinated (MgF ),
Alternatively, there are nitrides of binary alloys.

Various forming apparatuses and forming methods have been attempted for the purpose of forming a multilayer film by laminating such materials. Among them, the sputtering method is regarded as promising for the same reason as the above-mentioned formation of the gate oxide film.
Further, since the surface morphology of the deposited film is flat on an atomic scale order, the ECR sputtering method has been attracting attention as a promising method for forming a multilayer film.

Generally, in a sputtering apparatus for forming a thin film, scattered particles (sputtered particles) which are raw materials of the thin film.
However, it is empirically known to form a deposited film by adhering to a vacuum chamber wall or a shutter plate other than the sample stage on which the substrate is placed. The amount of the deposited film attached to the chamber wall changes depending on the positional relationship between the sputtering source and the sample stage. However, conventionally, no special measures have been taken for the film deposited on the chamber wall, assuming that the deposition on the substrate is not significantly affected.

As a result of investigating dust adhering to the wafer after forming the thin film, the inventors have found that in the conventional thin film forming method, the film adhering to the chamber wall has a stress of the film and an action of ions / electrons in plasma. It was discovered that it was peeled off due to electrostatic breakdown due to, causing dust. The findings are as follows.

(1) Sputtered particles adhere incompletely to the chamber wall other than the sample stage. (2) The incompletely deposited film is exposed to electrons and ions in plasma to generate dust due to electrostatic breakdown. (3) Even if the generation of dust due to electrostatic breakdown can be prevented,
As the deposited film thickness increases, the film stress causes the film to peel off and generate dust. (4) During electrostatic breakdown, a sudden discharge occurs and the plasma becomes unstable, damaging the thin film on the substrate.

FIG. 10 shows the structure of a conventional ECR sputtering apparatus. ECR sputtering equipment is chamber 1
001 and a plasma generation chamber 1002 communicating with this are provided. The chamber 1001 communicates with a vacuum exhaust device (not shown), and the inside of the chamber 1001 is vacuum exhausted together with the plasma generation chamber 1002 by the vacuum exhaust device. Chamber 1
001 is provided with a sample table 1004 to which a substrate (wafer) 1003 for film formation is fixed. Further, in the opening region in the chamber 1001 where the plasma from the plasma generation chamber 1002 is introduced, a ring-shaped target 1005 is provided so as to surround the opening region. The target 1005 is a container 10 made of an insulator.
05a, and the inner surface is exposed in the chamber 1001.

The plasma generation chamber 1002 is connected to a vacuum waveguide 1006, and the vacuum waveguide 1006 is connected to a waveguide 1008 through a quartz window 1007. The waveguide 1008 communicates with a microwave generator (not shown). A mode converter may be provided in the middle of the waveguide 1008. In addition, the ECR sputtering apparatus of FIG. 10 has the magnetic coil 1 around the plasma generation chamber 1002 and above the plasma generation chamber 1002.
It is equipped with 010.

In the ECR sputtering apparatus of FIG. 10, first,
After the chamber 1001 and the plasma generation chamber 1002 have been evacuated to a vacuum, an inert gas, argon gas, is introduced from the inert gas introducing section 1011 and a reactive gas such as oxygen is introduced from the reactive gas introducing section 1012. The pressure inside the plasma generation chamber 1002 is set to, for example, about 10 ⁻³ Pa. In this state, a magnetic field of 0.0875T is generated in the plasma generation chamber 1002 from the magnetic coil 1010, and then a microwave of 2.45 GHz is introduced into the plasma generation chamber 1002 through the waveguide 1008 and the quartz window 1007. Then, electron cyclotron resonance (ECR) plasma is generated.

As described above, a high frequency voltage is applied to the ring-shaped target 1005 provided between the plasma generation chamber 1002 and the sample stage 1004 while plasma is being generated, so that plasma is generated on the surface of the target 1005. It attracts and sputters. By sputtering, particles of the target material jump out from the surface of the target 1005 and reach the substrate 1003 together with the plasma emitted from the plasma generation chamber 1002. At this time, the reactive gas activated by plasma reaches the substrate 1003 together with the particles. As a result,
An oxide film of the target material is formed on the substrate 1003.

Here, considering the scattered region of the sputtered particles sputtered from the target 1005 by sputtering, the state of the divergent magnetic field and the plasma flow, as shown in FIG.
1 The inner sidewall is also reached and the target material is deposited there. Divergent magnetic field 11 formed by electromagnetic coil 1010
01 corresponds to the transport region of the ECR plasma generated in the plasma generation chamber 1002.

As described above, when a high frequency voltage is applied to the target 1005, the ions in the plasma collide with the target 1005 to cause a sputtering phenomenon, and the particles constituting the target 1005 are scattered in all directions. Among them, particles scattered in the direction of the sample table 1004 adhere to the substrate 1003 to form a thin film, which is irradiated with plasma extracted by a divergent magnetic field and is strong and of high quality due to the plasma assist effect. It becomes a film.

[0025]

However, the particles of the target scattered by the sputtering phenomenon also scatter in the inner sidewall direction of the chamber 1001 other than the direction of the sample stage 1004, and form a deposited film in the deposition region 1102, for example. Most areas of the deposited film formed in the deposition area 1102 are not irradiated with plasma, and are deposited as an incomplete film.

A plasma irradiation region 1103, which is a part of the plasma flow drawn out from the plasma generation chamber 1002, also exists in a part of the deposition region 1102. However, when the plasma flow drawn out from the plasma generation chamber 1002 by the divergent magnetic field exits the plasma generation chamber 1002, it rapidly spreads along the magnetic force lines together with the divergent magnetic field. Therefore, the spread plasma flow is entirely in the sample stage 1004.
Area is not poured, but the peripheral portion is irradiated to the inner side wall of the chamber 1001 to form a plasma irradiation area 1103.

The sample table 1004 is connected to the plasma generation chamber 1002.
The entire plasma flow by moving the sample table 1004
It is also possible to configure so that it will be accepted by. However, if they are brought close to each other in this way, the acceleration of ions due to the divergent magnetic field is insufficient, so that the ion assist effect on the film formed on the substrate 1003 is weakened. Therefore, in general, a part of the plasma flow extracted from the plasma generation chamber 1002 reaches the inner side wall of the chamber 1001 and forms the plasma irradiation region 1103.

The plasma irradiation area 1103 is the deposition area 1
A part of the deposition area 1102, which is a part of 102, is irradiated with plasma. However, the plasma reaching the inner side wall of the chamber 1001 has a low density,
Since the energy of ions is also low, an incomplete film is likely to be formed even when plasma is irradiated. Further, in the plasma irradiation region 1103, plasma is irradiated to a region where an incomplete film is formed, so that sudden discharge is likely to occur at the initial stage of plasma generation, and due to this discharge or electrostatic breakdown,
A part of the incomplete film formed in this portion may be peeled off and scattered.

Since the inside of the chamber 1001 is in a high vacuum state of about 0.01 Pa or less, the mean free path of particles is about 10 cm to 1 m, and a part of the scattered film flies around inside the chamber 1001 irregularly. , Substrate 1003
It adheres to the top and becomes dust, which causes deterioration of the film quality. Moreover, the above-mentioned sudden discharge makes the generation of plasma itself unstable, and this unstable plasma is generated by the substrate 1.
If it reaches above 003, the deposited film may be damaged.

The generation of dust and damage at the time of forming a film as described above is a big problem for the formation of a gate insulating film or a multilayer film, for example, and the influence becomes more remarkable as the substrate becomes larger in area. . For example, at present, many chips are simultaneously formed on a wafer (substrate) having a large area such as a diameter of 300 mm, and measures for reducing dust and damage are becoming more important. . The present invention has been made to solve the above problems, and an object of the present invention is to enable a thin film to be formed in a state in which damage due to dust or abnormal plasma is suppressed.

[0031]

A thin film forming apparatus according to one aspect of the present invention comprises a chamber that is evacuated to a predetermined pressure, a sample table that is placed in the chamber and mounts a substrate to be processed. A plasma generating means for generating a plasma of an inert gas and a reactive gas, a target placed on the upper part of the sample table and sputtered by the plasma generated by the plasma generating means, and a target between the target and the sample table. A plasma limiting cylinder made of a non-magnetic substance, which is arranged with the penetrating direction parallel to the center line toward the direction of the sample stage and which limits diffusion of plasma generated by the plasma generating means. is there. According to this thin film forming apparatus, the spread of the plasma between the target and the sample stage is limited, and the irradiation of the plasma on the inner wall of the chamber is suppressed.

In the thin film forming apparatus described above, the plasma generating means includes a plasma generating chamber communicating with the sample stage, a gas introducing means for introducing an inert gas into the plasma generating chamber, and a divergent magnetic field from the plasma generating chamber in the chamber direction. It is composed of a magnetic field forming means for forming and a microwave supplying means for supplying a microwave to the plasma generation chamber, and generates plasma in the plasma generation chamber by electron cyclotron resonance,
A divergent magnetic field is used to draw plasma toward the chamber, and the target is a ring-shaped one that is arranged at the boundary between the plasma generation chamber and the chamber, and applies a high-frequency voltage to the target. It is equipped with. In this thin film forming apparatus,
An auxiliary magnetic field forming means may be provided which is arranged in the direction opposite to the target of the sample stage and adjusts the divergence of the magnetic field formed by the magnetic field forming means.

In the thin film forming apparatus described above, the plasma generating means is a gas introducing means for introducing an inert gas and a reactive gas into the chamber, an RF electrode arranged to face the sample stage, and a high frequency power to the RF electrode. The target is disposed on the surface of the RF electrode facing the sample stage. Further, the thin film forming apparatus may be provided with a bias applying means for applying a bias for limiting the ion energy to the substrate, and with a rotating means for rotating the sample table, and the sample table is a method for measuring the surface of the sample. The line may be tilted so that it points in a direction different from the centerline.

In the above thin film forming apparatus, the inert gas is, for example, a rare gas, the reactive gas is, for example, oxygen gas, nitrogen gas, hydrogen, or a mixed gas thereof, and the target is, for example, , Aluminum, silicon, lithium, beryllium, magnesium, calcium, scandium, titanium, strontium, yttrium, zirconium, hafnium, or a lanthanum series element, or a plurality thereof.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. It is needless to say that the embodiment described below is just an example of the present invention, and the specific structure can be changed or improved without departing from the spirit of the present invention. Also, 1 Pa = 0.0076T
orr, and 1T = 10000 gauss. Further, sccm indicates that a fluid at 0 ° C. and 1.01325 × 10 ⁵ Pa flows 1 cm ³ per minute, and hereinafter, the gas flow rate indicates that nitrogen gas is replaced.

<Embodiment 1> FIG. 1 is a sectional view schematically illustrating an example of the structure of a thin film forming apparatus according to an embodiment of the present invention. The thin film forming apparatus of FIG. 1 firstly includes a chamber 101 and a plasma generation chamber 102 that communicates with the chamber 101. The chamber 101 communicates with a vacuum exhaust device (not shown), and the plasma generation chamber 1 is connected by the vacuum exhaust device.
With 02, the inside is evacuated.

The chamber 101 is provided with a sample table 104 to which a substrate (wafer) 103 on which a film is to be formed is fixed. Further, in the opening region in the chamber 101 where the plasma from the plasma generation chamber 102 is introduced,
A ring-shaped target 105 that surrounds the opening area.
Is provided. The target 105 is placed in a container 105a made of an insulator, and the inside surface is the chamber 1
It is exposed in 01. The target 105 may have a polygonal shape as well as a circular shape when viewed from above.

Further, the plasma generation chamber 102 communicates with a vacuum waveguide 106, and the vacuum waveguide 106 has a quartz window 107.
Is connected to the waveguide 108 via. Waveguide 108
Communicate with a microwave generator (not shown).
A magnetic coil (magnetic field forming means) 11 is provided around the plasma generation chamber 102 and above the plasma generation chamber 102.
0 is provided. The microwave generator, the waveguide 108, the quartz window 107, and the vacuum waveguide 106 constitute microwave supply means. The waveguide 10
There is also a configuration in which a mode converter is provided in the middle of 8.

In addition, in the thin film forming apparatus of the present embodiment, a cylindrical plasma limiting tube 113 for limiting the scattering area of the ECR plasma drawn from the plasma generation chamber 102 is provided below the target 105 (container 105a). Prepare The plasma limiting cylinder 113 is made of, for example, a non-magnetic material such as quartz or alumina. The plasma limiting cylinder 113 limits the divergence of the plasma flow that has been drawn from the plasma generation chamber 102 and passed through the region of the target 105, so that the irradiation region of the plasma flow on the surface defined by the surface of the sample table 104 is located on the sample table 104. It is to be put in the area of.

In the ECR sputtering apparatus of FIG. 1, first, the chamber 101 and the plasma generation chamber 102 are evacuated, then an inert gas, argon gas, is introduced from the inert gas introducing section 111, and the reactive gas is also introduced. Introductory part 11
A reactive gas such as oxygen is introduced from 2 to bring the inside of the plasma generation chamber 102 to a pressure of about 10 ⁻³ Pa, for example. In this state, after a magnetic field of 0.0875T is generated in the plasma generation chamber 102 by the magnetic coil 110, the waveguide 108,
2.4 into the plasma generation chamber 102 through the quartz window 107.
A microwave of 5 GHz is introduced to generate electron cyclotron resonance (ECR) plasma.

The ECR plasma forms a plasma flow toward the sample stage 104 by the divergent magnetic field from the magnetic coil 110. In the thin film forming apparatus of FIG. 1, microwave power supplied from a microwave generator (not shown) is once branched in the waveguide 108, and the plasma is supplied to the vacuum waveguide 106 above the plasma generation chamber 102. The generation chamber 102 is connected from the side through a quartz window 107. By doing so, the adhesion of scattered particles from the target 105 to the quartz window 107 can be prevented, and the running time can be greatly improved.

As described above, a high frequency voltage is applied to the ring-shaped target 105 provided between the plasma generation chamber 102 and the sample stage 104 while plasma is being generated, so that plasma is generated on the surface of the target 105. It attracts and sputters. By the sputtering, particles of the target material are ejected from the surface of the target 105 and reach the substrate 103 together with the plasma emitted from the plasma generation chamber 102. At this time, the reactive gas activated by plasma also reaches the substrate 103 together with the particles. As a result, on the substrate 103,
An oxide film of the target material will be formed. In addition, since the plasma extracted by the divergent magnetic field is irradiated onto the substrate 103, the film formed on the substrate 103 is more robust and of high quality due to the plasma assist effect of the irradiated plasma. Become.

Here, the scattering region of the sputtered particles sputtered from the target 105 by sputtering, the state of the divergent magnetic field and the plasma flow will be considered. As shown in FIG. 2, the magnetic lines of force formed by the electromagnetic coil 110 are
The divergence increases in the direction of 04. This magnetic field is called a divergent magnetic field 201. The divergent magnetic field 201 causes the EC generated in the plasma generation chamber 102 as described above.
The R plasma can be extracted as the plasma flow 202.

Here, in this embodiment, since the plasma limiting cylinder 113 is provided, the plasma flow 202 drawn out from the plasma generation chamber 102 does not irradiate the side wall inside the chamber 101, and almost all of the plasma flow 202 is provided on the sample stage 104. Irradiated on. On the other hand, as shown in FIG.
Part of the sputtered particles scattered from No. 5 is the chamber 10.
1 The inner sidewall is also reached and the target material is deposited there. However, according to the present embodiment, since the plasma limiting cylinder 113 is provided, the sputtered particles reaching the inner sidewall of the chamber 101 are also limited, and the chamber 10
The deposition of the film on the side wall of No. 1 is suppressed.

Further, even if a small amount of sputtered particles reach the side wall of the chamber 101 and a film is deposited, the plasma flow 202 is not radiated there. It is possible to prevent the occurrence of dielectric breakdown and the like. As a result, according to the present embodiment, the dust can be significantly reduced, and since the plasma flow is not irradiated on the inner side wall of the chamber 101,
Generation of abnormal plasma is also suppressed.

A part of the sputtered particles scattered from the target also reaches the inner wall of the plasma limiting cylinder 113,
A film is formed here, but since the plasma of the high density is irradiated to the inner wall of the plasma limiting cylinder 113, the formed film becomes complete and strong. Therefore, a film is formed on the inner wall of the plasma limiting cylinder 113, and the plasma is irradiated onto the inner wall of the plasma restricting cylinder 113, but a sudden discharge is not induced, and a part of the film is peeled off due to electrostatic breakdown or the like. It does not scatter.

Second Embodiment Next, another embodiment of the present invention will be described. FIG. 3 is a cross-sectional view schematically illustrating a configuration example of a thin film forming apparatus according to another embodiment of the present invention. This thin film forming apparatus is almost the same as the thin film forming apparatus shown in FIG. 1. First, a chamber 101 and a plasma generating chamber 102 communicating with the chamber 101 are provided, and the chamber 101 communicates with a vacuum exhaust device (not shown). There is. The chamber 101 includes a plasma generation chamber 1 in the chamber 101.
In the opening area into which the plasma from 02 is introduced, a ring-shaped target 105 is provided so as to surround the opening area. The target 105 is placed in a container 105a made of an insulator.

Further, the plasma generation chamber 102 communicates with a vacuum waveguide 106, and the vacuum waveguide 106 has a quartz window 107.
Is connected to the waveguide 108 via the plasma generation chamber 10
A magnetic coil 110 is provided around the periphery of the plasma generating chamber 102 and above the plasma generating chamber 102. Also in the thin film forming apparatus of FIG. 3, the ECR drawn from the plasma generation chamber 102 is located below the target 105 (container 105a).
Cylindrical plasma limiting tube 1 for limiting plasma scattering area
13 is provided. In addition, in the thin film forming apparatus of FIG. 3, the substrate 103 as the film forming target is fixed on the sample stage 104a which is inclined and rotated at a desired angle. Sample table 1
04a is rotatable by a rotating mechanism (not shown).

Also in the thin film forming apparatus of this embodiment, as shown in FIG. 4, the magnetic lines of force formed by the electromagnetic coil 110 have a divergence increasing toward the sample stage 104a. By the divergent magnetic field 201 due to this magnetic field, the EC generated in the plasma generation chamber 102 as described above.
The R plasma can be extracted as the plasma flow 202.

Here, also in this embodiment, since the plasma limiting cylinder 113 is provided, the plasma flow 202 drawn out from the plasma generation chamber 102 does not irradiate the side wall inside the chamber 101, and almost all of the plasma flow 202 is provided on the sample stage 104a. Irradiated on. On the other hand, as shown in FIG.
Part of the sputtered particles scattered from 05
01 The inner wall is also reached and the target material is deposited there. However, according to the present embodiment, since the plasma limiting cylinder 113 is provided, the sputtered particles reaching the inner side wall of the chamber 101 are also limited, and the chamber 1
The film deposition on the 01 side wall is suppressed.

Further, even if a small amount of sputtered particles reach the side wall of the chamber 101 and a film is deposited, the plasma flow 202 is not radiated there. It is possible to prevent the occurrence of dielectric breakdown and the like. As a result, according to the present embodiment, the dust can be significantly reduced, and since the plasma flow is not irradiated on the inner side wall of the chamber 101,
Generation of abnormal plasma is also suppressed.

The formation of an alumina thin film using pure aluminum as the target 105, oxygen as the reactive gas, and argon as the inert gas in the thin film forming apparatus of FIG. 3 will be described below. Argon is supplied to the plasma generation chamber 102 so that plasma can be stably obtained, and plasma is generated. For example, the supply flow rate of argon gas is 20 sccm, the supply flow rate of oxygen gas is 0 to 10 sccm, the microwave power introduced into the plasma generation chamber 102 is 500 W, and the high frequency power applied to the target 105 is 500 W. The substrate 103 is not heated.

Thus, the substrate 10 made of silicon
FIG. 5 shows typical characteristics of the oxygen flow rate dependence of the deposition rate and the refractive index of the alumina thin film formed on No. 3. As shown in FIG. 5, the alumina deposition rate increased with the increase of the oxygen gas flow rate to be supplied, and then gradually decreased at the maximum oxygen gas flow rate of about 4 sccm, and then rapidly decreased at the oxygen gas flow rate of about 7 sccm. , And settles at a small deposition rate of about 1/10 of the maximum value. The reason that the deposition rate sharply decreases when the oxygen gas flow rate is around 7 sccm is that the ratio of the oxidized aluminum on the surface of the target increases and the alumina becomes difficult to be sputtered. The deposition rate increases as the sputter rate increases, so if the target surface becomes less likely to be sputtered and the sputter rate decreases, the deposition rate also decreases. This phenomenon is a well-known phenomenon in the reactive sputtering method (Reference 3: Yutaka Kanehara, "Sputtering Phenomenon", The University of Tokyo Press, 120-132).
page).

On the other hand, the refractive index of the formed alumina film is
The oxygen gas flow rate sharply decreases near 4 sccm, and the refractive index is almost constant between about 1.6 and 1.65, which is close to the refractive index of the sapphire substrate satisfying the stoichiometric composition. The fact that the value of the refractive index appropriate for the alumina film is obtained by the measurement of the ellipsometer means that the formed film has high transparency and high film quality.

FIG. 6 shows a thin film forming apparatus (ECR sputtering apparatus) according to the present embodiment in which pure aluminum is used as a target and oxygen gas is used as a reactive gas.
The following shows the number of dusts in a silicon wafer (substrate) having a diameter of 8 inches with respect to the integrated film thickness when an alumina film is formed using argon gas as an inert gas. The dust was measured by forming an alumina film having a film thickness of 100 nm on the silicon wafer, and then measuring the dust attached to a portion of the silicon wafer excluding 5 mm around the periphery with a dust counter device. Further, the integrated film thickness was obtained by converting the deposition film thickness of the sample stage from the deposition rate and the deposition time for all depositions including the dummy process.

As shown in FIG. 6, the number of dusts tends to increase slightly as the integrated film thickness increases.
The number is as small as about 50 at 0 μm, which is suppressed to a value applicable to the silicon gate process. In a general sputtering method that does not use the plasma limiting cylinder according to the above-described embodiment, the number of dusts is usually several thousand or more,
It was said that it could not be applied to the gate process. On the other hand, by providing the plasma limiting cylinder described above, it is possible to suppress the generation of dust and significantly reduce the number of dusts, and the thin film forming apparatus of the present embodiment is provided with the number of dusts in a silicon gate process or the like. Can be adapted to the process where Further, after the integrated film thickness reaches 30 μm, it is possible to operate the thin film forming apparatus while suppressing an increase in the number of dusts by properly performing maintenance such as cleaning of the sample table and the inner wall of the chamber. Become.

<Third Embodiment> Next, another embodiment of the present invention will be described. FIG. 7 is a cross-sectional view schematically illustrating a configuration example of a thin film forming apparatus according to another embodiment of the present invention. In this thin film forming apparatus, an auxiliary coil 110a is newly added to the thin film forming apparatus shown in FIG. 3, and a mechanism (bias applying means) for applying a bias for controlling ion energy is provided to the sample stage 104a. It was done. The auxiliary coil 110a is arranged in the lower part of the apparatus on the side opposite to the side of the sample table 104a where the plasma is irradiated.
With the auxiliary coil 110a, the main magnetic coil 11
The degree of divergence of the divergent magnetic field formed by 0 can be controlled appropriately, and the effect of the plasma limiting cylinder 113 can be further enhanced.

<Fourth Embodiment> Next, another embodiment of the present invention will be described. FIG. 8 is a schematic sectional view showing a configuration example of a thin film forming apparatus according to another embodiment of the present invention.
In this embodiment mode, the RF sputtering apparatus is provided with the plasma limiting cylinder 813 made of a nonmagnetic material such as quartz or alumina. The thin film forming apparatus (RF sputtering apparatus) shown in FIG. 8 is provided with an RF electrode 802 to which high-frequency power is supplied from a high-frequency power supply means and a RF electrode 802 facing the RF electrode in a chamber 801 whose inside is evacuated by an unillustrated vacuum exhaust apparatus. A sample table 804 on which a plurality of substrates 803 are placed is provided.

An upper portion of the RF electrode 802 is covered with a cathode shield 805, and a target 806 is fixed to a lower surface of the RF electrode 802. Therefore, the target 806 and the sample table 804 are arranged to face each other. The plasma limiting cylinder 813 is arranged so as to surround a region below the target 806, and the plasma formed below the target 806 is supplied to the chamber 801.
Restrict the inner wall from reaching. The RF electrode 80
2 is fixed to the upper part of the chamber 801 by an insulating member 807.

In the RF sputtering apparatus of FIG. 8, the inside of the chamber 801 is made to have a predetermined vacuum degree, and then the sputtering gas and the reactive gas are introduced from the gas introduction section 811 to obtain an appropriate gas pressure. Then, a high frequency voltage is applied to the RF electrode 802 to generate RF plasma below the RF electrode 802. Due to the existence of the plasma limiting cylinder 813, the generated plasma is in a state of being confined in the region inside the plasma limiting cylinder 813 without reaching the inner wall of the chamber 801. In this state, since a negative bias for attracting ions is applied to the target 806, the surface of the target 806 is sputtered by the ion bombardment in the plasma inside the plasma limiting cylinder 813, and as a result, the sputtered particles scattered. , Is deposited on the substrate 803 to form a thin film.

Further, sputtered particles scattered as a result of sputtering are scattered in all directions, but since the plasma limiting cylinder 813 is provided, it is possible to limit the sputtered particles scattered to the inner wall of the chamber 801.
As a result, even in the thin film forming apparatus of FIG. 8, film deposition on the sidewall of the chamber 801 is suppressed. Further, even if a small amount of sputtered particles reach the side wall of the chamber 801, and a film is deposited, plasma irradiation is limited here, so that insulation that causes dust due to peeling of the film occurs. It is possible to prevent triggering such as destruction. As a result, even in the present embodiment, the dust can be significantly reduced, and the chamber 80
1. Since plasma is not irradiated on the inner side wall, generation of abnormal plasma is also suppressed.

As described above, the plasma limiting cylinder is not limited to the cylindrical shape, but may be an elliptical cylinder or a cylinder having a polygonal cross section. In addition, as shown in FIG.
As shown in (b), the plasma limiting cylinders 913 and 913a may be provided with an eaves-shaped portion on the upper portion. In addition, FIG.
As shown in (a) and (b), plasma limiting cylinders 913,
The upper portion of 913a may be arranged apart from the lower portion of the container 105a of the target 105. By using the plasma limiting cylinder 913, the influence of the differential pressure can be eliminated. Further, as shown in FIG. 9C, the plasma limiting cylinder 913b may have a shape in which the diameter becomes smaller as the distance from the target 105 increases.

[0063]

As described above, according to the present invention, the spread of the generated plasma is limited.
An excellent effect that a thin film can be formed in a state in which damage due to dust or abnormal plasma is suppressed is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration example of a thin film forming apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an enlarged part of FIG.

FIG. 3 is a cross-sectional view showing a configuration example of a thin film forming apparatus according to another embodiment of the present invention.

4 is an enlarged sectional view showing a portion of FIG.

FIG. 5 is a characteristic diagram showing typical characteristics of oxygen flow rate dependency of deposition rate and refractive index of an alumina thin film.

FIG. 6 shows the number of dust particles in the substrate with respect to the integrated film thickness in the thin film forming apparatus according to the present embodiment.

FIG. 7 is a cross-sectional view showing a configuration example of a thin film forming apparatus according to another embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a configuration example of a thin film forming apparatus according to another embodiment of the present invention.

FIG. 9 is a sectional view showing a partial configuration example of a thin film forming apparatus according to another embodiment of the present invention.

FIG. 10 is a sectional view showing a configuration of a conventional thin film forming apparatus.

11 is a cross-sectional view showing an enlarged part of FIG.

[Explanation of symbols]

101 ... Chamber, 102 ... Plasma generation chamber, 103
... Substrate (wafer), 104 ... Sample stage, 105 ... Target, 106 ... Vacuum waveguide, 107 ... Quartz window, 108 ... Waveguide, 110 ... Magnetic coil, 111 ... Inert gas introduction part, 112 ... Reactivity Gas introduction part, 113 ... Plasma limiting cylinder.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiro Ono             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Masaru Shimada             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Seitaro Matsuo             4-16-30 Shimorenjaku, Mitaka City, Tokyo             Inside Nutty Afty Co., Ltd. F-term (reference) 2H048 GA04 GA60                 4K029 AA06 AA24 BA01 BA03 BA17                       BA35 BA43 BA44 BD01 CA05                       DC02 DC27 DC35 DC48                 5F045 AA19 AB31 AB32 AB33 AB34                       BB15 DP03 DQ10 EH17 EH20

Claims (7)

[Claims] 1. A chamber that is evacuated to a predetermined pressure, a sample stage that is placed in the chamber and mounts a substrate to be processed, and plasma generation that generates plasma of an inert gas and a reactive gas. Means, a target arranged on the upper part of the sample table and sputtered by the plasma generated by the plasma generating means, and a center line extending from the target toward the sample table between the target and the sample table. And a plasma limiting cylinder made of a non-magnetic material, which is arranged in parallel with the through direction and limits diffusion of the plasma generated by the plasma generating means. 2. The thin film forming apparatus according to claim 1, wherein the plasma generating unit includes a plasma generating chamber that communicates with the sample stage, a gas introducing unit that introduces the inert gas into the plasma generating chamber, It is composed of a magnetic field forming means for forming a divergent magnetic field from the plasma generation chamber in the chamber direction, and a microwave supply means for supplying microwaves to the plasma generation chamber, and generates plasma in the plasma generation chamber by electron cyclotron resonance. , The plasma is drawn out in the chamber direction by the divergent magnetic field, the target is arranged in a boundary portion between the plasma generation chamber and the chamber, and is formed in a ring shape. A thin film forming apparatus comprising a high frequency voltage applying means for applying a voltage. 3. The thin film forming apparatus according to claim 2, wherein the thin film forming apparatus is arranged in a direction opposite to the target of the sample stage,
A thin film forming apparatus comprising an auxiliary magnetic field forming means for adjusting the divergence of the magnetic field formed by the magnetic field forming means. 4. The thin film forming apparatus according to claim 1, wherein the plasma generating unit is arranged to face the sample stage, and a gas introducing unit that introduces the inert gas and the reactive gas into the chamber. An RF electrode and power supply means for supplying high-frequency power to the RF electrode, and the target is arranged on a surface of the RF electrode facing the sample stage. . 5. The thin film forming apparatus according to claim 1, further comprising a bias applying unit that applies a bias that limits ion energy to the substrate. 6. The thin film forming apparatus according to claim 1, further comprising a rotating unit that rotates the sample table, wherein the sample table has a normal line to the center line. Is a thin film forming apparatus, which is inclined so as to face in different directions. 7. The thin film forming apparatus according to claim 1, wherein the inert gas is a rare gas, and the reactive gas is oxygen gas, nitrogen gas, hydrogen, or a mixture thereof. The target is any one of a mixed gas, and the target is composed of any one or more of aluminum, silicon, lithium, beryllium, magnesium, calcium, scandium, titanium, strontium, yttrium, zirconium, hafnium, or a lanthanum series element. A thin film forming apparatus characterized in that