JPH073446A - Ect sputtering device and substrate cleaning method using for sputtering device - Google Patents

Abstract

PURPOSE:To provide the ECR sputtering device capable of forming high-quality films on a substrate and the substrate cleaning method using the ECR sputtering device capable of completely cleaning the substrate within the device. CONSTITUTION:A film forming chamber 1 disposed adjacently to a plasma chamber 7 is provided with a plasma introducing hole 4 communicating with this plasma chamber 7. This plasma introducing hole 4 is provided with first and second targets 15, 17. The respective targets 15, 17 are provided with first, second shutters 25, 27 covering these targets. The film forming chamber 1 is provided with a substrate holder 1 on which the substrate is mounted. The holder 2 side is provided with a shutter 26 covering the substrate 3. The ECR plasma is first generated in the plasma chamber 7 while all the shutters 25, 26, 27 are held closed as shown in (a), then the shutter 26 is opened like (b) and the plasma is brought into collision against the substrate 3 to clean the substrate 3; thereafter, the shutters 25, 27 are opened, by which the thin films of the first, second target 15, 17 materials are formed on the substrates 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ECR sputtering apparatus for forming a thin film on a substrate and a substrate cleaning method using the ECR sputtering apparatus.

[0002]

2. Description of the Related Art ECR as one means for forming a thin film
(Electron cyclotron resonance) sputtering method is used.
As shown in FIG. 5, the apparatus for carrying out this method is provided with a film forming chamber 1 and a plasma chamber 7 adjacent to each other. Deposition chamber 1
A substrate holder 2 is provided inside, and a substrate 3 is attached to the substrate holder 2. The substrate holder 2 is provided with a heater (not shown) as a heating means for heating the substrate 3. A plasma introducing hole 4 communicating with the plasma chamber 7 is formed on the wall surface of the film forming chamber 1 facing the substrate 3.
The cylindrical target 5 is mounted on the wall surface of the film forming chamber 1 with the plasma introduction hole 4 as the center. The inner peripheral surface of the target 5 is a sputtering surface 6, and this sputtering surface 6 is a surface orthogonal to the substrate 3.

A vacuum waveguide 8 is connected to the plasma chamber 7, and a microwave waveguide 11 is connected to an inlet side of the vacuum waveguide 8 through a microwave introduction window 10 to supply a microwave electric field. Has been done. Further, the plasma chamber 7 is provided with coils 12 and 13 for applying a magnetic field. In addition, the film forming chamber 1 is configured such that the inside of the film forming chamber 1 is in a vacuum state by an exhaust system such as a vacuum pump. The configuration example of the film forming equipment is the same as that shown in the document of Matsuoka and Ono (Applied Physics, Vol. 58, No. 8, page 1217).

Next, a method of forming a thin film using the apparatus shown in FIG. 5 will be described. First, the target 5 is arranged at the exit of the plasma chamber 7, that is, at the film formation chamber side of the plasma introduction hole 4 of the film formation chamber 1. A substrate 3 is attached to the substrate holder 2, and an exhaust system is driven to bring the inside of the film forming chamber 1 into a vacuum state. The substrate 3 is preheated by a heater. Plasma chamber 7
A discharge gas, for example, an argon (Ar) gas is introduced into the inside. In the film forming chamber, the pressure is, for example, 1.0 × 10 ⁻⁴ to ⁴ depending on the flow rate of the discharge gas from the plasma chamber 7 and the exhaust from the exhaust system.
Adjust to 0 × 10 ⁻⁴ Torr. By supplying a microwave electric field to the plasma chamber 7 from the waveguide 11 through the microwave introduction window 10 and the vacuum waveguide 8 and applying a magnetic field by the coils 12 and 13, Ar gas is excited and plasma is generated.
The plasma in the plasma chamber 7 becomes a plasma flow due to the divergent magnetic fields of the coils 12 and 13 and is drawn into the film forming chamber 1. A negative target voltage is applied to the target 5,
When the plasma in the plasma chamber 7 collides with the sputtering surface 6 of the target 5, target particles are emitted. The target particles are deposited on the surface of the substrate 3.

In this case, the composition forming the target 5 is a composition of the same element as the thin film to be formed on the substrate 3, for example, if the thin film on the substrate 3 is a thin film of indium antimonide (InSb). , InSb of the same composition.

However, when the target particles are deposited on the substrate to form a thin film, the elements constituting the thin film are re-evaporated from the heated substrate. In the conventional ECR sputtering method, as a result of re-evaporation, the composition of the thin film deviates from the stoichiometric composition, for example, In: Sb = 1: 1 in the case of InSb, and a high vapor pressure element such as antimony
There was a problem of shortage of b). That is, the conventional ECR
In the sputtering method, it was difficult to match the composition of the thin film with the stoichiometric composition when the vapor pressures of the elements of the composition were greatly different.

Therefore, the inventors of the present invention have provided a thin film forming method that solves the above-mentioned drawbacks, and an ECR sputtering apparatus that carries out this thin film forming method. That EC
The R sputtering device is a device as shown in FIG.
A characteristic of this ECR sputtering apparatus is that a first target 15 and a second target 17 are arranged adjacent to each other in the plasma introduction hole 4 and a first power source 19 for supplying power to the first target 15 is provided. And a second power source 20 for supplying power to the second target 17, and at least one of the first and second power sources 19 and 20 is configured to be able to vary the power to be supplied. The configuration and function are similar to those of the device shown in FIG. In FIG. 4, the first and second targets 1
5,17 is supported in the target holder 16, 18 formed in a tubular shape with copper or stainless steel, the first power source 19 a frequency of the high frequency power source of about 13.56 MH _Z, the second power supply It is a direct current power source with variable power.

According to this ECR sputtering apparatus, for example, a main composition of a thin film formed on the substrate 3, for example, In
Sb is provided as the first target 15, while as the second target 17, an element having a high vapor pressure among the composition elements of the thin film formed on the substrate 3, for example, Sb is provided, and the first and second targets are provided. The target 15 and 17 of the second target 17 are simultaneously sputtered with plasma, and the second power source 20 is varied to adjust the power supplied to the second target 17 to control the amount of target particles emitted from the second target 17. Under the control, the composition of the thin film formed on the substrate 3 is stoichiometrically matched by compensating for the element that has a high vapor pressure and easily evaporates among the composition elements of the thin film formed on the substrate 3. It is like this.

Further, a multilayer thin film can be formed by using the same device as that shown in FIG. In this case, first, the first power source 19 is turned on and the second power source 20 is turned off, power is supplied only to the first target 15 to deposit the material of the first target 15 on the substrate 3, Then, conversely, the second power supply
With only 20 turned on, the material of the second target 17 is deposited on the material film of the first target 15 deposited on the substrate 3.
Then, in this way, the first and second power sources 19 and 20 are turned on.
The process of turning off is alternately repeated, and films of the materials of the first and second targets 15 and 17 are alternately formed and laminated to form a multilayer thin film.

[0010]

[Problems to be Solved by the Invention] However, each power source
When supplying power from 19 and 20 to each target 15 and 17,
Immediately after the start of discharge, the discharge is unstable, and each target 15,
Target material 1 due to inadequate power supply to 17
There is a problem that 5 and 17 are not properly sputtered and a clean thin film is not formed. When a multilayer film is formed by alternately turning on and off each power source 19 and 20, the film is formed at the interface between layers. There was a problem that the quality of the product deteriorated.

When forming the multilayer film, the first power source is used.
Even if only 19 is turned on and only the material of the first target 15 is deposited, the first target 15 and the second target 17 are adjacent to each other. Part of the particles may collide with the second target 17, causing some of the particles of the second target 17 to be ejected and deposited with the particles of the first target 15. It has been difficult to stack them in a uniform state with no impurities and with high precision.

Further, in the ECR sputtering apparatus as shown in FIGS. 4 and 5, a mechanism for cleaning the substrate 3 in the apparatus before the targets 5, 15 and 17 are formed on the substrate 3 by sputtering is incorporated. Therefore, even if the substrate 3 is cleaned before being mounted in the apparatus, dust such as carbon and metal in the air adheres to the substrate 3 or the surface of the substrate 3 before the substrate 3 is mounted. There is also a problem in that the surface of the substrate 3 is contaminated due to the oxidization of oxygen and the accuracy of the film formed on the substrate 3 deteriorates. When a semiconductor or a dielectric is formed using these films, the performance of the semiconductor or the like also deteriorates.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an ECR sputtering apparatus capable of forming a high quality thin film having a uniform layer composition and the like on a substrate, and a substrate. It is an object of the present invention to provide a substrate cleaning method using an ECR sputtering device capable of completely cleaning the substrate.

[0014]

In order to achieve the above object, the present invention is constructed as follows. That is, the ECR sputtering apparatus of the present invention has a plasma chamber for generating ECR plasma, a film forming chamber adjacent to the plasma chamber and having a plasma introduction hole communicating with the plasma chamber, and the substrate is placed in the film forming chamber. A substrate holder that is detachably attached is provided, a plurality of targets are arranged in the plasma introduction hole, and an independent shutter that covers the target is provided on each target side so as to be openable and closable. Further, a shutter that covers the substrate is provided on the substrate holder side so as to be openable and closable, which is also a characteristic configuration of the ECR sputtering apparatus of the present invention.

Further, according to the substrate cleaning method using the ECR sputtering apparatus of the present invention, the target is provided in the communicating portion of the film forming chamber which is adjacently arranged in communication with the plasma chamber, and the substrate is arranged in the film forming chamber. Before the thin film is formed on the substrate by sputtering, the target is covered with a shutter, ECR plasma is generated in the plasma chamber with the shutter closed, and the plasma is made to collide with the substrate to clean the substrate. Has been done.

[0016]

In the ECR sputtering apparatus of the present invention having the above structure, a plurality of targets are arranged in the plasma introduction hole, and each target is provided with an independent shutter for covering the target so that it can be opened and closed. By supplying power to the target with the shutter of each target closed, and opening the shutter when the power supplied to the target is appropriate, and sputtering, the target material is sputtered on the substrate in the optimum state. To be formed.

Further, each shutter can be opened and closed independently, and by adjusting the opening and closing, it becomes possible to form a thin film having a high quality such as a composition of the film on the substrate, and also when forming a multilayer film. Thus, it becomes possible to form a film having a good interface between layers and a composition of each layer.

Further, in the substrate cleaning method using the ECR sputtering apparatus of the present invention having the above structure, the target material is covered with the shutter before the thin film is formed on the substrate by the sputtering of the target material, and the plasma is kept in the state where the shutter is closed. Since the ECR plasma is generated in the chamber, the plasma collides with the substrate without colliding with the target material. Then, when the plasma collides with the substrate, dust and the like attached to the surface of the substrate are repelled and the substrate is completely cleaned.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same parts as those of the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted. Figure 1
Shows an example of the ECR sputtering apparatus according to the present invention. The main difference of this embodiment from the ECR sputtering apparatus shown in FIG. 4 is the first and second shutters 25 and 27 that cover the first and second targets 15 and 17 independently of each other. And a substrate 3 on the substrate holder 2 side.
That is, the substrate shutter 26 for covering the above is provided. The first and second shutters 25 and 27 are shutter opening / closing mechanisms 30 and 32, respectively.
Is connected to a motor that is an external drive mechanism by a magnetic fluid seal, and the shutters 25 and 27 can be automatically opened and closed freely by the action of the shutter opening and closing mechanisms 30 and 32. 26 is a shutter opening / closing mechanism 31
The shutter opening / closing mechanism 31 can freely open and close the shutter, like the first and second shutters 25 and 27. In addition, the first and second power supplies 19 and 20 connected to the first and second targets 15 and 17, respectively, are configured to be able to vary the power to be independently supplied to the substrate holder 2. Is connected to a high frequency power source 33 so that a voltage can be applied to the substrate 3 by applying it to the substrate holder 2.

"Specific Example 1"

The ECR sputtering apparatus of this embodiment is configured as described above. Next, a method for cleaning a substrate using this ECR sputtering apparatus and a silicon germanide (SiGe) film is formed after cleaning the substrate. An example will be described with reference to FIG. First, in FIG.
The target 15 is made of silicon in a cylindrical shape, and the second target 17 is made of germanium in a cylindrical shape. In addition,
The targets 15 and 17 are supported by the target holders 16 and 18, respectively, and the first and second shutters 25 and 27 and the substrate shutter 26 are closed as shown in FIG.

Next, the substrate 3 of a 100-direction silicon wafer that has been previously treated with hydrofluoric acid is attached to the substrate holder 2. Although this substrate 3 has been previously treated with hydrofluoric acid, it may be exposed to the air before being washed with water or attached to it, so that dust may adhere to its surface or a natural oxide film 34 of several nm may be formed. It has been done.

Next, after the substrate 3 is attached, the chamber 3 is evacuated to evacuate the film forming chamber 1 and the substrate 3 is heated to 400 to 700 ° C.
Heat to. In addition, argon (A
r) introducing a gas, while introducing a microwave of 2.45 GHz _Z, by applying a magnetic field 875Gauss by coils 12 and 13, to generate ECR plasma by exciting the Ar gas.

When the ECR plasma is generated, the substrate shutter 26 is opened by the shutter opening / closing mechanism 31 to expose the substrate 3 to the ECR plasma, as shown in FIG.
By making the ECR plasma collide with the surface of the substrate 3,
The native oxide film 34 and dust on the surface of the substrate 3 are completely removed, and the substrate 3 is cleaned. At this time, 0.3 W / cm is applied to the substrate 3 by the high frequency power source 33 connected to the substrate holder 2.
High-frequency power of ² or less or negative DC bias voltage of 2.0 U or less in absolute value may be applied. If you do that, EC
The R plasma is more likely to collide with the substrate 3, and the substrate 3 can be efficiently cleaned.

After the cleaning of the substrate 3 is completed as described above, next, the first and second power sources 19 and 20 connected to the first and second targets 15 and 17 are turned on. A negative voltage is applied to each target 15 and 17, and the first and second
When the target 15 and 17 of No. 1 are pre-sputtered and the electric power is supplied to the first and second targets 15 and 17 to stabilize the discharge, as shown in FIG. 32 opens the first and second shutters 25 and 27. When the shutters 25 and 27 are opened, the ECR plasma collides with the first and second targets 15 and 17 to which the negative target voltage is applied, and the target particles are emitted to deposit on the surface of the substrate 3 and the silicon germanium thin film. 35 are formed.

Therefore, by using the ECR sputtering apparatus of this embodiment, the substrate 3 is placed in the film forming chamber 1 and each thin film is formed on the substrate by sputtering the first and second targets 15 and 17. The targets 15 and 17 are covered with the shutters 25 and 27, respectively, and the shutters 25 and 27 are closed.
If CR plasma is generated, and the plasma is collided with the substrate 3 to clean the substrate 3, the generated ECR plasma collides directly with the surface of the substrate 3 without colliding with the targets 15 and 17, and the substrate 3 is The cleaning can be performed perfectly, and since the ECR plasma is not high enough to damage the substrate 3, the cleaning by the ECR plasma does not damage the substrate 3 but causes an oxide film or dust on the surface of the substrate 3. Can be removed.

Since the target material can be continuously formed after the cleaning of the substrate 3, the substrate is not soiled again after the cleaning, and the target material is deposited on the substrate 3 in a perfectly clean state. The accuracy of the formed thin film can be improved.

Further, when the target material is deposited on the substrate 3 after the cleaning of the substrate 3,
The first and second shutters 25 and 27 are closed until the applied voltage of 5 and 17 is variably controlled until they are in an appropriate state. When the appropriate state is reached, the shutters 25 and 27 are opened and the sputtering is performed. Since the film is formed, the target particles are deposited by sputtering with the applied voltage to each target 15 and 17 being at an optimum state, and it is possible to form a clean thin film having a uniform film composition and the like.

"Specific Example 2"

Next, an example of producing a multilayer film of strontium titanate (SrTiO ₃ ) and barium titanate (BaTiO ₃ ) using the above ECR sputtering apparatus will be described. First, as shown in (a) of FIG.
25, 26, 27 are S as the first target 15 in the closed state.
rTiO ₃ is formed in a cylindrical shape, and BaTiO ₃ is formed in a cylindrical shape as the second target 17. Next, a mixed gas of oxygen is introduced into the plasma chamber 7, and the substrate 3 is cleaned in the same manner as in Example 1 to remove dust and the like. In this example, the film formed on the substrate 3 is an oxide film, and the surface of the substrate 3 may be oxidized.

Then, as in Example 1, the first and second targets 15 and 17 were pre-sputtered, and when the voltages of the first and second targets 15 and 17 became appropriate, (a) in FIG. ), The first shutter 25 is opened to deposit SrTiO ₃ which is the first target 15 material on the substrate 3 to form a film, and then, as shown in FIG. Then, the shutter 25 is closed and the second shutter 27 is opened to deposit BaTiO ₃ as the second target 17 material on the SrTiO ₃ film 37 to form a BaTiO ₃ film 38. Then again
Of the SrTiO ₃ film 37 and the BaTiO ₃ film by alternately opening and closing the first and second shutters 25 and 27 such that only the shutter 25 of the SrTiO ₃ film 37 is opened to deposit the SrTiO ₃ film 37.
A multi-layered film superlattice in which films 38 are alternately stacked can be formed.

That is, also in the second specific example, the substrate 3 is cleaned and the same effect is obtained as in the first specific example.
Even when a multilayer film is formed on the substrate 3, the first and second targets 15 and 17 are always sputtered by an appropriate target applied voltage and the target particles are deposited, so that each layer is a high quality film. Since the films are alternately formed, the quality of the film does not deteriorate at the interface between layers, and a high quality multilayer film is manufactured.

Further, as shown in FIG. 3A, when the SrTiO ₃ film 37 of the first target 15 material is formed, the second shutter 27 is closed and the second target 17 is formed.
The material BaTiO ₃ particles are never sputtered and mixed with SrTiO ₃ to form a film, and conversely, when the BaTiO ₃ film 38 of the second target 17 material is formed, SrTi
Since no O ₃ particles are mixed in, the composition of each layer is uniform without impurities, and a high quality film is formed.

The present invention is not limited to the above-mentioned embodiments, but various embodiments can be adopted. For example, in the above embodiment, the formation of the SiGe film and the formation of the multilayer film of SrTiO ₃ and BaTiO ₃ by the ECR sputtering device were described as specific examples, but the film formed by the ECR sputtering device is not limited to those films. For example, In
Various films such as Sb film can be formed.

Although the shutter 26 is provided on the substrate holder 2 side in the above embodiment, the shutter 26 does not necessarily have to be provided on the substrate holder 2 side, and in that case also, the shutters 25 and 27 are first and second. A high-quality film can be formed by adjusting the opening and closing of. However, if the shutter 26 is also provided on the substrate holder 2 side, after cleaning the substrate 3,
When the discharge of the first and second targets 15 and 17 is not stable, the first and second shutters 25 and 27 are opened with the shutter 26 closed until the discharge is stable, and when the discharge is stable. It is also possible to open the shutter 26 on the side of the substrate holder 2 to deposit the first and second targets 15 and 17, and the operation for forming a high quality thin film becomes easier.

Further, in the above embodiment, the shutters 25, 2
The shutter opening / closing mechanisms 30, 31, 32 are configured to automatically open / close the shutters 6, 27, but the shutters 25, 26, 27 are not necessarily opened / closed automatically. It may be done by means.

Further, in the above embodiment, both the first and second power sources 19 and 20 are variable power sources, but both the first and second power sources are not necessarily variable power sources, either of which is variable. One may be variable, or neither may be variable. Further, in the specific example 2 of the above-described embodiment, the first and second shutters 25 and 27 are opened and closed with the switches of the first and second power sources 19 and 20 left turned on. Switch on / off according to opening / closing of 27
You can turn it off.

Although the high frequency power supply 33 is connected to the substrate holder 2 in the above embodiment, the high frequency power supply 33 need not necessarily be connected to the substrate holder 2.

Further, in the above embodiment, the targets 15,
Although 17 is set as two targets, the number of targets is not limited to two and may be three or more.

Further, the substrate cleaning method using the ECR sputtering device of the present invention does not always use the ECR sputtering device provided with a plurality of targets as in the above embodiment, and at least covers the target on the target side. If a shutter is provided, the target is covered with the shutter before the thin film is formed on the substrate by the sputtering of the target material using the ECR sputtering device having one target, and the target is generated in the plasma chamber with the shutter closed. The substrate can also be cleaned with ECR plasma.

[0041]

According to the ECR sputtering apparatus of the present invention,
Since each target has an independent shutter that can be opened and closed to cover the target, the discharge of each target is stable, and the shutter is closed until it becomes optimal, and the shutter is opened when the discharge becomes optimal. Since the target material is sputtered to form a thin film, it is possible to form a clean, high-quality film having a uniform composition.

Further, since the shutter on each target side functions independently, for example, by opening and closing two shutters alternately for two targets, a multilayer film in which target materials are alternately laminated can be formed. By adjusting the opening and closing of the shutter as well as the number and types of films, it can be applied to the formation of various films, and moreover, when forming each layer, it is possible to reliably and selectively deposit only the target particles to be deposited. Therefore, the formed film does not contain impurities in each layer, has high quality, and can be a very high-quality film as a whole.

Further, according to the substrate cleaning method using the ECR sputtering apparatus of the present invention, the target is covered with the shutter before the thin film is formed on the substrate by sputtering the target material, and the ECR plasma is generated with the shutter closed. In order to clean the substrate by colliding with it,
The ECR plasma directly collides with the surface of the substrate without colliding with the target, repels dust and the like on the substrate, and can completely clean the substrate. Further, since the energy of ECR plasma is not large enough to damage the substrate, the substrate surface is cleaned without being damaged, and after cleaning,
Since the shutter on the target side can be opened continuously to form a thin film on the substrate by the target material, the target material is deposited on the substrate in a perfectly clean state. The accuracy of the film can be improved. A semiconductor using such a high-quality film can improve its mobility, and a dielectric can improve its dielectric constant.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an ECR sputtering apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a step of forming a film on a substrate by cleaning the substrate using the ECR sputtering apparatus of the above embodiment.

FIG. 3 shows the first and second ECR sputtering devices of the above embodiment.
FIG. 9 is an explanatory view of a main part showing a multilayer film forming step by alternately opening and closing the shutters 25 and 27 of FIG.

FIG. 4 is an explanatory diagram showing an ECR sputtering apparatus previously proposed by the present inventors.

FIG. 5 is an explanatory diagram showing a conventional ECR sputtering apparatus.

[Explanation of symbols]

 1 film forming chamber 3 substrate 4 plasma introduction hole 5,15,17 target 7 plasma chamber 25,26,27 shutter

Claims (3)

[Claims] 1. A substrate having a plasma chamber for generating ECR plasma and a film forming chamber adjacent to the plasma chamber and having a plasma introduction hole communicating with the plasma chamber, wherein the substrate is detachably attached to the film forming chamber. An ECR sputtering apparatus characterized in that a holder is provided, a plurality of targets are arranged in a plasma introduction hole, and an independent shutter for covering the target is provided on each target side so as to be openable and closable. 2. The EC according to claim 1, wherein a shutter for covering the substrate is provided on the substrate holder side so as to be openable and closable.
R sputtering device. 3. A target is provided in a communicating portion of a film forming chamber that is adjacently placed in communication with a plasma chamber, a substrate is arranged in the film forming chamber, and a target is formed before forming a thin film on the substrate by sputtering a target material. Is covered with a shutter, ECR plasma is generated in the plasma chamber with the shutter closed,
A substrate cleaning method using an ECR sputtering device, characterized in that the plasma is made to collide with the substrate to clean the substrate.