JPS639584B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a plasma deposition apparatus for forming thin films of various materials on a sample substrate in the manufacture of electronic devices such as semiconductor integrated circuits, and in particular to a plasma deposition apparatus that uses plasma. The present invention relates to a plasma deposition apparatus for forming high-quality thin films of metals and metal compounds at low temperatures.

(Prior art) Conventionally, film forming equipment using plasma can be broadly divided into sputtering equipment and plasma
There is a CVD device. The former mainly targets metal films or metal compound films, and the latter mainly targets metal films or metal compound films.
It targets thin film formation of silicon-based materials such as SiO ₂ , Si ₃ N ₄ , and Si.

From a raw material supply method, the former targets a solid material and bombards it with ions, causing spatter atoms emitted from the solid surface to adhere and deposit on the substrate on which the film is to be formed, thereby forming a film. The latter is supplied in the form of a raw material gas. For example, gases such as SiH ₄ , N ₂ or O ₂ are decomposed and reacted using plasma to produce Si ₃ N ₄ and
A film such as SiO ₂ is formed on the substrate.

Plasma using conventional high-frequency discharge plasma
In the CVD method, it is necessary to heat the sample substrate to 250°C to 400°C, and the quality of the formed Si ₃ N ₄ film is also insufficient in terms of density.

In contrast, plasma was generated using microwaves under electron cyclotron resonance conditions, and a divergent magnetic field was used to draw the plasma onto the sample stage, causing ion bombardment with moderate energy.
The ECR plasma deposition method is proposed in Japanese Patent Application No. 55-57877 (Japanese Unexamined Patent Publication No. 56-155535) and the corresponding U.S. Patent Application No. 257616, which describes a low-temperature deposition method without substrate heating. With this method, it is possible to form silicon-based films such as Si ₃ N ₄ that are dense and of high quality comparable to high-temperature CVD methods.

However, in the case of film formation of metals and metal compounds, there is no suitable gas such as SiH ₄ for silicon-based materials, and the only gases that can be supplied in gas form are halogens such as fluoride, chloride, and bromide. Limited to compounds. In order to supply these halides, heating and a special introduction system are required, and decomposition by plasma is difficult or unstable, making it difficult to obtain a good quality film.

In addition, in the conventional sputtering method, the ionization and ion energy of atoms incident on the sample substrate are not controlled to promote the film-forming reaction, and a high-quality film with good adhesion cannot be obtained at low temperatures. It was hot.

(Purpose) The present invention has been made in view of the above circumstances, and its purpose is to achieve both the ease of supplying raw materials by the sputtering method and the film forming characteristics of the ECR plasma deposition method, and to achieve both. It is an object of the present invention to provide a plasma deposition apparatus that can solve the above drawbacks and form thin films of an extremely wide range of materials such as metals and metal compounds stably at low temperatures and with good quality.

Another object of the present invention is to provide a plasma deposition apparatus that allows for extensive control over the properties of the films formed.

Still another object of the present invention is to provide a plasma deposition apparatus with high deposition efficiency.

Yet another object of the invention is easy maintenance;
An object of the present invention is to provide a plasma deposition apparatus with improved film formation yield.

Still another object of the present invention is to provide a plasma deposition apparatus that increases target current and increases deposition rate.

Still another object of the present invention is to provide a plasma deposition apparatus that allows for easy use of targets of a variety of materials.

(Structure of the Invention) In order to achieve the above object, the plasma deposition apparatus of the present invention includes a plasma generation chamber for introducing gas to generate plasma, and a sample stage for placing a sample substrate on which a film is to be formed. , a sample chamber in which a thin film is attached and deposited on the sample substrate, a plasma extraction window placed between the plasma generation chamber and the sample chamber, and a plasma extraction window and a sample stage formed into a cylindrical shape by sputtering material. a first target which is arranged to surround the plasma flow between the first target and the second target, and a first target which extracts ions for sputtering the target from a part of the plasma flow generated by the plasma generated in the plasma generation chamber and injects them into the target.
and second means for directing the plasma stream through the plasma extraction window into the sample chamber and transporting the sputtered atoms to the sample substrate, sputtering the target with such ions and transferring the sputtered atoms into the plasma stream. The sputtering material is taken in, transported to a sample substrate, and made incident on the sample substrate to form a thin film of a sputtering material or a thin film of a compound or alloy containing the elements of the sputtering material on the sample substrate.

In the present invention, it is preferable that the above-mentioned target be placed near the plasma extraction window and in contact with the plasma flow.

Here, it is preferred that the surface of the cylindrical target to be sputtered intersects a part of the plasma stream.

Here, in the plasma generation chamber, it is preferable to generate plasma by electron cyclotron resonance discharge using microwaves.

In the present invention, the first means described above may include a sputter power supply connected so that the target becomes negative.

Further, in a preferred embodiment of the present invention, the second means described above includes a magnetic coil having a magnetic field distribution of a diverging magnetic field in which the magnetic field strength weakens with an appropriate gradient from the plasma generation chamber to the sample chamber.

Here, it is preferable to cover the portion of the target that does not face the plasma flow with a shield electrode.

Furthermore, it is preferred to cool the shield electrode, thereby cooling the target by radiative heat conduction.

Furthermore, a cylindrical target can be constructed by concentrically stacking cylinders made of multiple types of target materials, or by stacking cylinders with approximately the same diameter made of multiple types of target materials in the direction of the plasma flow. It can be configured as follows.

Alternatively, the cylindrical target can be formed from a plurality of electrically independent target sections, each of which can be independently connected to a separate sputtering power supply, thereby allowing independent control of sputtering for each target section. You can do it like this.

Further, it is preferable to electrically insulate the above-mentioned sample stage from the plasma generation chamber.

Furthermore, the first gas introduction system may be provided only in the plasma generation chamber, or the first gas introduction system may be provided in the plasma generation chamber and the second gas introduction system may be provided in the sample chamber.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, where 1 is a plasma generation chamber and 2 is a sample chamber. 3 is a microwave introduction window, which in this embodiment is made of a quartz glass plate. As a microwave source (not shown) of the microwaves guided from the rectangular waveguide 4 to the plasma generation chamber 1 via the microwave introduction window 3, a magnetron with a frequency of 2.45 GHz, for example, can be used.

In the plasma generation chamber 1, a plasma extraction window 5 is provided at the other end facing the microwave introduction window 3, and a plasma flow 6 is extracted from the generated plasma through this window 5, and a sample substrate 7 is placed thereon. the sample table 8. The sample chamber 2 is connected to an exhaust system 9. This exhaust system 9 includes, for example, an exhaust capacity adjustment valve, a liquid nitrogen trap, and an exhaust capacity of 2400/2.
It can be configured with a sec oil diffusion pump and an oil rotary pump with a pumping capacity of 500/min (both not shown).

It is convenient for the plasma generation chamber 1 to be placed under the conditions of a microwave cavity resonator so as to increase the microwave electric field strength and the efficiency of microwave discharge. Therefore, as one such example, a circular cavity resonance mode TE ₁₁₂ was adopted, and the plasma generation chamber 1 was made into a cylindrical shape with inner dimensions of 15 cm in diameter and 15 cm in height.
According to calculations, a diameter of 15cm satisfies this condition.
The height is approximately 14 cm, but considering the change in the wavelength of left-handed circularly polarized waves after plasma generation, a height of 15 cm was adopted as mentioned above. Note that the wavelength of the right-handed circularly polarized wave that directly couples with the cyclotron motion electrons becomes sufficiently short due to plasma generation, and after plasma generation, there is no need to strictly define the height dimension. The plasma extraction window 5 can be, for example, a circular window with a diameter of about 6 cm.

A magnetic coil 10 is installed around the outer periphery of the plasma generation chamber 1, and the strength of the magnetic field generated by this is controlled by electron cyclotron resonance (ECR) using microwaves.
It is assumed that the following conditions are established in at least a portion of the interior of the plasma generation chamber 1. 11 is a magnetic shield. For microwaves with a frequency of 2.45 GHz, this condition is a magnetic flux density of 875 G, so the magnetic coil 10 is configured to generate a maximum magnetic velocity density higher than this. Also, magnetic coil 1
The magnetic field generated by 0 is not only used for electron cyclotron resonance in the plasma generation chamber 1, but also extends to the sample chamber 2, and the strength of the magnetic field in the sample chamber 2 is equal to It is also used to form a diverging magnetic field that decreases at an appropriate gradient from the window 5 toward the sample stage 8, and thereby to draw out the plasma flow 6 from the plasma generation chamber 1 to the sample stage 8.

Due to the interaction between the magnetic moment of the circularly moving electrons, which have become in a high-energy state due to electron cyclotron resonance, and the magnetic field gradient of the divergent magnetic field, the electrons are accelerated while making circular motions in the direction of the sample stage 8 along the magnetic field lines. . However, since the surface of the sample stage 8 and the plasma generation chamber 1 are configured to be electrically insulated,
The sample stage 8 generates a negative potential, and in the plasma flow,
An electric field is generated that decelerates electrons and accelerates ions, and conditions are maintained such that the same number of electrons and ions reach the sample stage 8. That is, with this divergent magnetic field configuration, the energy of electrons is converted into the energy of ions incident on the sample stage 8, and efficient adhesion and film-forming reactions occur due to appropriate ion bombardment. The ion energy in this case is about 5 to 30 eV, and its value can be controlled by microwave power, gas pressure, etc. Therefore, the film quality can be freely controlled for thin films made of a wide range of materials.

As a gas introduction system, Ar is introduced into the plasma generation chamber 1.
A first gas introduction system 12 that introduces plasma generation gas such as N ₂ , O ₂ , H _{2 ,} etc. and a sample chamber 2 containing SiH ₄ , N ₂ , O ₂
It has two systems including a second gas introduction system 13 that introduces raw material gas such as. Note that this second gas introduction system 1
3 may not be necessary depending on the thin film to be formed. In addition, cooling water is allowed to flow through the wall of the plasma generation chamber 1 from the water supply port 14, and the cooling water is discharged from the drain port 15.
to cool down. Further, the sample stage 8 and the magnetic coil 10 can also be cooled in the same manner.

The above structure can be substantially the same as the plasma deposition apparatus disclosed in the above-mentioned Japanese Patent Application No. 57877/1983.

Further, in the sample chamber 2, a right cylindrical sputtering target 41 made of a sputtering material such as Al, Mo, or Nb is placed in the vicinity of the plasma extraction window 5 so as to surround the plasma flow 6 and come into contact with the plasma flow 6. Place. Here, the target 41 is attached to a ring-shaped target holder 42, and the part of the target 41 that does not face the plasma flow 6 is covered with a shield electrode 43 at ground potential with a gap of 5 to 10 mm. prevent abnormal discharge such as spark discharge or the incidence of unnecessary ions.

A cooling pipe 44 is disposed on the outer surface of the shield electrode 43, and cooling water is supplied to the cooling pipe 44 from a water supply port 45 and drained from a drain port 46. Thereby, the shield electrode 43 is cooled, and the sputtering target 41 is thereby cooled by radiant heat conduction. Thereby, film formation can be stabilized.

Radiant heat conduction in a vacuum can be theoretically determined by the Stephan-Boltzmann law, and is proportional to the fourth power of absolute temperature. According to this, the temperature is 200
℃ or above, sufficient heat transfer becomes possible, and the sputtering target 41 can be effectively cooled. In this embodiment, since the surface of the cylindrical target 41 is perpendicular to the surface of the sample substrate 7,
The heat radiated from the surface of the target 41 has almost no effect on the sample substrate 7. Therefore, in this configuration, it is only necessary to cool the target 41 itself to a temperature at which it does not deform or change in quality, and a sufficient effect can be obtained by cooling by radiant heat conduction. Furthermore, since there is no need to provide a cooling mechanism for the target 41 itself, this is very effective in simplifying the target structure.

Also, from the point of view of film formation, the target 41
Negative ions are generated on the surface of the target and may be ejected perpendicularly to the target surface due to the energy of the target voltage, causing damage to the sample surface in the conventional sputtering method. The high-energy particles are incident on the target surface again and do not reach the sample surface. Therefore, no damage to the sample surface occurs, and only particles with optimal energy for film formation reach the sample surface.

Again, in FIG. 1, the sputtering target 41 is further connected to the sputtering power source 19 via the holder 42. This power supply 19 is, for example, a DC power supply with a maximum voltage of 1000V and a maximum current of 1A. As the sputtering power source 19, a high frequency power source can also be used in the same way as the high frequency sputtering device.

When the power source 19 is connected so that the sputtering target 41 becomes negative, and argon (Ar) gas is introduced from the first gas introduction system 12 to generate plasma, as shown in FIG. The argon ions Ar ⁺ in the plasma flow 6 cause the sputtering target 41 to have a negative potential (-100 to -1000V).
The atom of the metal M constituting the sputtering target 41 is sputtered and ejected into the plasma stream 6. In the plasma flow 6, these spatter atoms are ionized by collision with electrons.
M ⁺ , and as explained earlier, the plasma flow 6
Due to the electric field induced by the divergent magnetic field in the
The ions M ⁺ are transported in the direction of the sample stage 8, and are given appropriate energy and directionality to promote the film-forming reaction, enter and adhere to the sample substrate 7, and are deposited to form a film of metal M. It is formed.

As shown in FIG. 2, there is a strong magnetic field on the upstream side of the plasma flow 6 and a weak magnetic field on the downstream side, so the interaction between the magnetic field gradient due to the magnetic field and the negative potential of the target 41 surface causes electrons to e, including secondary electrons from the target surface, are trapped between the plasma stream 6 and the surface of the target 41, increasing the plasma density near the target surface of the plasma stream.
As a result, abnormal discharge can be prevented and ionization efficiency can be improved.

Next, specific examples of the characteristics of the plasma deposition apparatus of the present invention will be described. When plasma is generated by introducing Ar gas into the first gas introduction system 12, stable discharge occurs in an extremely wide gas pressure range where the gas pressure in the plasma generation chamber 1 is 1×10 ^-5 Torr to ^{10 -2} Torr or higher. I was able to do this. A particularly optimal gas pressure range was 1×10 ⁻⁴ Torr to 1×10 ⁻² Torr.

When the sputtering target 41 is made of Al, the microwave power is 100W, and the voltage of the sputtering power source 19 is 500V, the target 41
An ionic current of 400 mA was applied to the At this time, a sputtering reaction occurred on the sputtering target 41 due to argon ion bombardment, and the entire plasma flow took on a deep blue color, and it was observed that Al atoms were sputtered uniformly.

According to the present invention, as shown in FIG. 2, the sputtered M atoms are ionized in the plasma stream 6 to become M ⁺ , and are transported onto the sample stage 8 together with the plasma stream 6 to form a thin film. , so the area where the plasma flow 6 irradiates the sample stage 8, in this example,
The film is formed only in an area of 15 cmφ, and therefore, efficient film formation is possible. In addition, it is possible to form a film with good uniformity in this area, and the center 10cm
In the region of φ, uniformity of ±5% or less was obtained.

Furthermore, since the attached ions and other ions in the plasma flow have appropriate energy as described above, it is possible to form a film of good quality with good adhesion. Despite forming an Al film at room temperature,
It was possible to form a mirror-like film with extremely good adhesion and a thickness of 1 μm. Furthermore, even when a material with extremely low adhesion, such as Teflon, was used as a substrate, a film could be formed on it with extremely good adhesion.

A mixed gas of Ar and O ₂ (or only O ₂ gas) is introduced from the first gas introduction system 12, or
Ar and second gas introduction system 1 from gas introduction system 12
By introducing O ₂ from No. 3 and combining it with the sputtering target Al, a dense and high quality Al ₂ O ₃ film can be formed at low temperature. Also,
By introducing _N2 instead of _O2 , AlN film,
Furthermore, by using various metals such as Mo, W, Ta, Nb, and other materials as the material for the sputtering target 16, it is possible to form films of these materials, or even oxide or nitride films of these materials. can. For example, by introducing SiH ₄ gas from the second gas introduction system 13,
It is possible to form alloys of Si and metals and silicide films such as MoSi ₂ and WSi ₂ . That is, in the present invention, by selecting the gases to be introduced from the first gas introduction system 12 and the second gas introduction system 13, selecting the target material for sputtering, and combining these, it is possible to produce very different types of films such as metal films, compound films, and alloy films. Thin films of a wide range of materials can be formed at low temperatures and with extremely high quality.

Regarding the shape and structure of the target 41, in addition to the one obtained by processing a band-shaped metal material into a cylindrical shape as shown in the above example, there are other structures such as a structure in which a band-shaped target material is attached to the inner peripheral surface of a cylindrical base. Of course, it may be of various sizes and shapes depending on the application.

In the embodiment described above, the target electrode 4
1 and the shield electrode 43 are formed in a cylindrical shape, but they do not necessarily have to be formed in a continuous cylindrical shape, but may be divided into one or more parts facing the plasma flow 6 to form a cylindrical shape. May be placed.

A specific example of the sputtering target portion in the plasma deposition apparatus of the present invention shown in FIG. 1 is shown in FIG. Here, the shield electrode 43 consists of an upper shield electrode 43A, a lower shield electrode 43B, and an outer shield electrode 43C.
The flange portion 43D of 3C is fixed to the upper wall 2A of the sample chamber 2 with screws 47. Since the shield electrode 43 is at ground potential, it can be directly fixed to the sample chamber with screws 47. Upper and lower shield electrodes 43A
and 43B have a structure of a hollow flange disk, and both of them or only the lower shield electrode 43B can be attached and detached using screws 48. Furthermore, for example, MACOR is used for the shield electrode 43B.
A ring-shaped insulating spacer 49 made of processing ceramic such as (trade name of Corning Glass Works) is attached, and the target 41 attached to the target holder 42 is supported by this spacer 49.

In this example, since the target 41 is a right cylinder, its structure is simple, and it is only necessary to arrange a strip-shaped target material in a cylindrical shape along the holder 42. Therefore, it can be easily and inexpensively applied to various materials. You can configure targets. In a specific example, the ring-shaped holder 42 has a thickness of 5 mm and an inner diameter of 84 mm, and the cylindrical target 41 has a thickness of 2 mm. Since the target 41 can be made thin in this way, it can be easily formed into a cylindrical shape using various strip-shaped materials, and the target can be easily replaced.

A support cylinder 50 is provided protruding from the holder 42, and an electrode 52 is fixed inside the support cylinder 50, one end of which contacts the back surface of the target 41, and the other end of which has a receiving hole for a pin 51 that supplies power from the power source 19. do. The pin 51 is fixed to the insulating tube 53, and the insulating tube 53 is attached to the support tube 50.
It is possible to fit into the Another insulating tube 54 is fixed to the insulating tube 53, and a pin 5 is installed inside this insulating tube 54.
1 and the connection part between the power supply line 55 from the power source 19 is accommodated. As described above, the pin 51 is made detachable from the electrode 52, and power from the power source 19 is supplied to the target 4.

Furthermore, a cooling pipe 44 is disposed on the outer circumferential shield electrode 43C to cool the sputtering target 41 by radiant heat conduction, and also to prevent the temperature of the sample substrate and the inside of the sample chamber from rising due to the heat of the target. Stabilization can be achieved. In such a configuration, the plasma chamber 1
The ions 56 in the plasma flow generated by the plasma sheath 57 and transported by the effect of the divergent magnetic field are efficiently transferred to the plasma sheath 57.
The target current can be increased and the deposition speed can be improved. Further, due to the negative potential on the target surface and the effect of the magnetic field gradient, electrons are captured between the plasma generation chamber 1 and the sputtering target 41, preventing abnormal discharge and
Ionization efficiency can be improved.

Figure 4 shows a more detailed example of Figure 3.
An example of mounting a belt-shaped cylindrical target is shown in Fig. 3 C-
It is shown in the cross section of part C'. Here, 41
A is an inner cylindrical target, 41B is an outer cylindrical target, 42 is a support ring, D is a seam of target 41A, and E is a seam of target 41B. When using a belt-shaped target material in a cylindrical form, if the joints are not completely sealed, the lower part, in this case the support ring 42, will be exposed. When such elements are present, different elements are mixed into the film, making it impossible to obtain a thin film of desired purity. Generally, as a countermeasure of this type, joining the joint portions by welding is taken. However, depending on the material, welding itself may not be possible, or even if welding is possible, impurities may be mixed into the welded part, and especially in the case of thin plates, the bulge in the welded part may make it difficult to precisely attach the cylindrical target. It was making it difficult. In the present invention, by using two cylindrical strip targets stacked one on top of the other, it is possible to simply and easily attach the target. The cylindrical target is simply molded to a desired diameter, and the joints do not require welding or other joining, and can be installed so that joints D and E do not overlap, as shown in FIG. At this time, the cylindrical target can be fixed if the cylindrical target is mounted under a force that causes it to open outward. Furthermore, during sputtering, the cylindrical target is firmly fixed by thermal stress.

FIG. 5 shows the effect of the present invention, and shows the relationship between microwave power and target current.
Gas is Ar (8×10 ^-2 Pa), target voltage is 500V
And so. Target current is target area 100cm ²
It's a hit. Curve A is the case when the conical cylindrical target disclosed in Japanese Patent Application No. 156843/1988, which was previously proposed by the applicant, is used instead of the cylindrical target in the present invention, and curve B is the case when the conical cylindrical target disclosed in the patent application No. 156843, which was previously proposed by the applicant, is used. This is the case for a right cylindrical target according to the invention. In curve B, as mentioned above, due to the ion influx effect and the electron trapping effect, 3 of curve A
More than double the target current was obtained. Also,
Even when such a large current (large power) was applied to the target, it was possible to operate stably for a long time due to the cooling effect of the target.

FIG. 6 is a diagram showing the relationship between target voltage and target current in the sputtering target of the present invention. The gas was Ar (8×10 ^-2 Pa). The target current increases rapidly up to a target voltage of 50V, and remains at a nearly constant value above that point.
Also, this target current can be controlled by microwave power. Therefore, the optimum target current and voltage can be applied freely and with good controllability to targets made of various materials.

FIG. 7 shows an example of film deposition according to the present invention, in which Ta is used as the target 41, Ar gas is introduced from the first gas introduction system 12, and O ₂ is introduced from the second gas introduction system 13 to form a Ta ₂ O ₅ film. The figure shows the case where . The total flow rate of Ar and O ₂ was 15 c.c./min, and the target power was 3 W/cm ² . The substrate 7 was made of Si and was fixed to a water-cooled sample stage 8. The substrate temperature was approximately 45°C. The deposition rate decreases as the O ₂ flow rate ratio increases. In contrast, the refractive index is the O ₂ flow rate ratio
Up to 0.25, it decreases as the O ₂ flow rate ratio increases, but at higher O ₂ flow rate ratios, it becomes constant at a value specific to the Ta ₂ O ₅ film. Because highly active ECR plasma is used, Ta and O ₂ can be deposited at a high speed of 200 Å/min.
The reaction proceeded satisfactorily, and a high-quality film having a refractive index unique to the film was obtained with good adhesion. Furthermore, although the film is formed at a low temperature without heating the substrate 7, the etching rate with buffered hydrofluoric acid (50% hydrofluoric acid: 40% ammonium fluoride = 1:1, 20°C) is approximately 20%.
Å/min, and compared to films obtained by conventional sputtering methods or thermal oxidation methods, which require heating the substrate to approximately 500°C, a film was formed that was equivalent or more dense. Furthermore, by applying this Ta ₂ O ₅ film to the gate film of a MOS diode, we obtained a specific inductivity of 22, and confirmed good diode characteristics with very little generation of interface states due to surface damage and low surface charge.

As described above, in the sputter type ECR plasma deposition method using the sputtering target having the structure and arrangement of the present invention, sputtering targets made of various materials can be easily used. A high quality thin film can be formed at a low temperature by the combination of the following. In the explanation so far, a case has been described in which one type of target material is used and a thin film is formed in combination with a gas. However, since the structure of the sputtering target is simple, it becomes possible to easily form a thin film of a metal compound or alloy using a plurality of target materials.

Two examples of using multiple target materials in this manner are shown in FIGS. 8 and 9.

FIG. 8 shows an example in which two types of target materials are used, and an outer cylindrical target 61 is attached inside the ring-shaped holder 42. Inside this outer cylindrical target 61, first and second inner cylindrical targets 62 and 63 are stacked in two layers, upper and lower, in the direction of the plasma flow. Preferably, the outer cylindrical target 61 is constructed of the same material as either the first or second inner cylindrical target 62 or 63. A sputter voltage is applied to the entire target from a sputter power supply 19. The composition ratio of the two types of materials in the thin film can be freely controlled by the ratio X/Y of the widths X and Y of the first and second inner cylindrical targets 62 and 63.

FIG. 9 shows an example in which sputtering voltage can be applied independently to two types of target materials. In this example, two ring-shaped holders 7
2 and 73 are electrically insulated, and first outer and inner cylindrical targets 74 and 75 and second outer and inner cylindrical targets 76 and 77 are placed inside each holder 72 and 73, respectively. Attach. In this example, two cylindrical targets are placed within the shield electrode 43 with an insulating ring 71 interposed therebetween. For these two targets, first and second sputter power supplies 19A and 19 as sputter power supplies 19 are connected.
It is possible to apply sputter voltages individually and independently from B.

When a thin film is formed by arranging two types of target materials in this way, the spatter particles fly to the center of the plasma flow and are transported to the sample stage by the transport effect of the plasma flow, so that they are spread within the plane of the sample surface. A very homogeneous thin film is formed. Furthermore, since a target made of a single material is used, non-uniformity in the thickness direction of the thin film due to temporal changes in spatter components, which is a problem with mixed targets, does not occur. Furthermore, it is a very effective means when forming thin films of materials with extremely different sputtering rates or when it is necessary to delicately control the sputtering speed. In the above explanation, the case where targets of two types of materials are used has been described, but it is also effective when using three or more types of targets, and can be easily applied to the formation of thin films made of a wide variety of materials.

(Effects) As explained above, according to the present invention, atoms of a solid material are emitted by sputtering using a solid material as a raw material for forming a thin film, the sputtered atoms are ionized by a plasma flow, and the sputtered atoms are attached to and react with. Since the film is formed by applying the optimum kinetic energy to the film, by combining this with the introduction of various gases, it is possible to form films of an extremely wide range of materials at low temperatures and with high quality. In addition, unlike conventional sputtering equipment, the present invention generates plasma independently of sputtering using electron cyclotron resonance using microwaves, thereby achieving an extremely wide range of 10 ^-5 Torr to ^{10 -2} Torr or more. The sputtering reaction can be stably generated at a gas pressure of . Furthermore, according to the present invention,
The kinetic energy imparted to the sputtering atoms can be varied by microwave power, the gas pressures of various introduced gases can be set over a wide range, and the partial pressures of the gases from the two introduction systems can also be set appropriately. Therefore, the properties of the formed film can be controlled over a wide range. Moreover, the ionized spatter atoms and molecules are directionally transported onto the sample substrate by the plasma flow, which not only increases the efficiency of deposition but also prevents unnecessary film formation on other parts of the sample chamber. Since this does not occur, there is an advantage that there is less wear on the target and less contamination inside the device, which also contributes to ease of maintenance and improvement of yield.

Furthermore, according to the present invention, highly active plasma can be obtained even under low gas pressure, so various compounds such as oxides and nitrides can be formed at high speed and with high quality by introducing a reactive gas. In addition, since plasma generation conditions and adhesion reaction conditions can be controlled independently,
The physical properties of the membrane can be easily controlled. Since the ion energy is at an appropriate level of about 5 to 30 eV, the film formation reaction is promoted, the film has good adhesion, and damage to the semiconductor surface is extremely small. Since films can be formed at low temperatures, films of various materials can be formed on polymeric materials and resists. Therefore, ultra-LSI manufacturing, GaAs,
The present invention is effective in manufacturing thermally unstable compound semiconductor devices such as InP, and can also be widely applied to coating various materials.

Furthermore, when the sputtering target is shaped like a right cylinder and its surface intersects with the plasma flow, the ions in the plasma flow are efficiently incident on the target surface, increasing the target current and improving the deposition rate. do. Along with that,
Electrons are captured by the interaction between the negative potential of the target and the divergent magnetic field, thereby promoting ion production and preventing abnormal discharge. Further, since the straight cylindrical target has a simple structure, the strip-shaped target material can be easily bent into a cylinder, and targets made of various materials can be used easily and at low cost. By using a plurality of strip target materials, thin films of various alloys can be easily and uniformly obtained. Additionally, in this case, since the target plane is perpendicular to the sample direction,
The target can also be cooled by cooling the shield electrode, which can be easily water-cooled.Therefore, since there is no need to attach a cooling pipe to the target, the target can be easily replaced.

Furthermore, in the above-described embodiments of the present invention, sputtering with an inert gas such as Ar is used to supply the metal _M. It is also possible to supply the metal M solely by reactive sputtering to improve the deposition rate. From the perspective of the method of supplying metal M by sputtering, halogen-based gases generally involve a chemical reaction that produces volatile halides than inert gases such as Ar, so the sputtering speed is much higher, and therefore, The supply efficiency of the metal M is increased, and the deposition rate can be improved. In this case, the metal halide that has jumped out into the plasma stream is decomposed by collision with the electrons in the plasma stream.
Ionized, it looks like ECR plasma deposition method (Application Serial No. 257616 Patent Application 1987-57877)
A thin film can be formed using the same mechanism as that in which a metal halide gas is introduced in
However, in this case, a solid target of metal M is used and the metal halide is supplied by a reactive sputter, so a special gas introduction system is not required, and metal halides with high boiling points can also be easily supplied. be.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
The figure is an explanatory diagram of the principle of plasma deposition according to the present invention.
FIG. 3 is a cross-sectional view showing a specific example of the structure of the target and shield electrode in the present invention shown in FIG. 1, and FIG. 4 is a cross-sectional view showing a detailed example of the target.
FIG. 5 is a characteristic curve diagram showing the relationship between microwave power and target current according to the present invention, and FIG. 6 is a characteristic curve diagram showing the relationship between target voltage and target current according to the present invention using microwave power as a parameter. FIG. 7 is a characteristic curve diagram showing Ta ₂ O ₅ film adhesion characteristics according to the present invention, and FIGS. 8 and 9 are cross-sectional views showing two further embodiments of the present invention. 1...Plasma generation chamber, 2...Sample chamber, 2A...
... Upper wall, 3 ... Microwave introduction window, 4 ... Rectangular waveguide, 5 ... Plasma extraction window, 6 ... Plasma flow, 7 ... Sample substrate, 8 ... Sample stage, 9 ... Exhaust system , 10... Magnetic coil, 11... Magnetic shield, 12... First gas introduction system, 13... Second gas introduction system, 14... Water supply port, 15... Drain port, 19
...Sputtering power supply, 19A...First sputtering power supply, 19B...Second sputtering power supply, 41...Sputtering target, 42...Holder, 43...
...shield electrode, 43A...upper shield electrode,
43B... Lower shield electrode, 43C... Outer shield electrode, 43D... Flange portion, 44... Cooling pipe, 45... Water supply port, 46... Drain port, 47...
...Screw, 48...Screw, 49...Spacer, 50
... Support cylinder, 51 ... Pin, 52 ... Electrode, 53
...Insulated tube, 54...Insulated tube, 55...Power line,
56... Ions in plasma flow, 57... Plasma sheath, 61... Outer cylindrical target, 62
...first inner cylindrical target, 63...second
Inner cylindrical target, 71...insulation ring,
72...Ring-shaped holder, 73...Ring-shaped holder, 74...First outer cylindrical target, 75
...first inner cylindrical target, 76...second
Outer cylindrical target, 77... second inner cylindrical target.

Claims (1)

[Scope of Claims] 1. A plasma generation chamber in which a gas is introduced to generate plasma; a sample chamber in which a sample stage is arranged for placing a sample substrate on which a film is to be formed; the plasma generation chamber and the sample chamber; a plasma extraction window disposed between the two; a target made of a sputtering material into a cylindrical shape and disposed between the plasma extraction window and the sample stage so as to surround the plasma flow; ions for
a first means for extracting a part of the plasma flow caused by the plasma generated in the plasma generation window and causing it to enter the target; A plasma deposition apparatus comprising: a second means for transporting to a sample substrate. 2. The plasma deposition apparatus according to claim 1, wherein the target is disposed near the plasma extraction window and in contact with the plasma flow. 3. A plasma deposition apparatus according to claim 1, wherein a surface of the cylindrical target to be sputtered intersects a part of the plasma flow. 4. In the plasma deposition apparatus according to any one of claims 1 to 3, the plasma generation chamber is configured to generate the plasma using electron cyclotron resonance discharge using microwaves. A plasma deposition device characterized by: 5. In the plasma deposition apparatus according to any one of claims 1 to 4, the first means includes a sputter power source connected so that the target becomes negative. Plasma deposition equipment. 6. In the plasma deposition apparatus according to any one of claims 1 to 5, the second means has a weak magnetic field strength with an appropriate gradient from the plasma generation chamber to the sample chamber. 1. A plasma deposition apparatus characterized by having a magnetic coil having a magnetic field distribution of a diverging magnetic field. 7. The plasma deposition apparatus according to any one of claims 1 to 6, characterized in that a portion of the target that does not face the plasma flow is covered with a shield electrode. Plasma deposition equipment. 8. The plasma deposition apparatus according to claim 7, wherein the shield electrode is cooled. 9. In the plasma deposition apparatus according to any one of claims 1 to 3, the cylindrical target is configured by concentrically stacking cylinders made of a plurality of types of target materials. Characteristic plasma deposition equipment. 10. In the plasma deposition apparatus according to claim 1, 2, 3, or 9,
A plasma deposition apparatus characterized in that the cylindrical target is constructed by stacking cylinders of substantially the same diameter made of a plurality of types of target materials in the flow direction of the plasma flow. 11 Claims 1, 2, 3,
In the plasma deposition apparatus according to either paragraph 9 or 10, the target is formed from a plurality of target portions, each of the target portions being independently connected to a separate sputtering power supply, A plasma deposition apparatus characterized in that sputtering of each target portion can be independently controlled. 12. A plasma deposition apparatus according to any one of claims 1 to 11, characterized in that the sample stage is electrically insulated from the plasma generation chamber. 13. In the plasma deposition apparatus according to any one of claims 1 to 12,
A plasma deposition apparatus characterized in that the plasma generation chamber is provided with a first gas introduction system. 14. The plasma deposition apparatus according to claim 13, wherein the sample chamber is provided with a second gas introduction system.