JPH05295552A - Plasma treating device - Google Patents

Abstract

PURPOSE:To eliminate plasma leakage and to increase the energy of the ions jumping to a substrate surface so as to speed up film forming or etching by using a vacuum chamber formed to a shape of enclosing a space where plasma is formed as an electrode for plasma generation. CONSTITUTION:This plasma treatment device is formed of a discharge means 6, the electrode and voltage supplying means for generating the plasma in a vacuum vessel, a means 8 for supplying gas to a plasma generating section, etc. This vacuum vessel is formed to the shape of enclosing the plasma space. The vacuum vessel is connected to the above-mentioned voltage supplying means 7 without grounding the vacuum vessel and is used as the electrode vacuum chamber 1 to generate the plasma. The grounding member in the vacuum vessel is formed of a substrate 2 and a mounting member. Further, an earth cover 3 is disposed in the atm. outside the vacuum vessel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus such as a film forming processing apparatus and an etching processing apparatus using plasma, and in particular, a substrate to be processed is intermittently transported and sequentially plasma-processed while the substrate is stationary. The present invention relates to a plasma processing apparatus suitable for a continuous processing type plasma processing apparatus that performs processing.

[0002]

2. Description of the Related Art As is well known, a substrate to be treated as it is or one mounted on a holder or the like is sequentially fed into a reaction vessel to generate plasma to modify or etch the surface of the substrate to be treated, After forming a thin film on the surface of the substrate to be treated, the apparatus for continuously plasma-treating a large number of substrates by repeating the step of feeding the substrate,
Widely used in industry. As an example of this, there is known a sputtering film forming apparatus for sequentially forming a multilayer film of a magnetic disk or an optical disk as disclosed in JP-A-62-502846.

On the other hand, as a high-frequency plasma processing method, a method of performing etching with high-energy ions or ion-assisted film formation by utilizing the self-bias effect caused by the asymmetry of the electrode area is well known, for example, reactive ion etching. A high hardness carbon film is formed. In these treatments, the treatment is usually performed on the electrode on which the high frequency is applied.
As disclosed in Japanese Laid-Open Patent Publication No.-83471, if the same processing is performed on the ground side substrate by increasing the area of the high frequency electrode, a great industrial effect is obtained. That is, in consideration of the above-mentioned continuous multi-layer processing, it was very advantageous to be able to keep the substrate at the ground potential, for example, in constructing a transfer device.

FIG. 8 is a sectional view showing a structural example of a conventional typical plasma processing apparatus for performing plasma processing on a disk substrate to be processed. In the figure, 16 is a grounded vacuum chamber in which an electrode vacuum chamber 17 for generating plasma is arranged via an insulator 5. The earth cover 3 connected to the vacuum chamber 16 is provided at a predetermined interval on the outer periphery of the electrode vacuum chamber 17,
Has a ground shield. Furthermore, the electrode vacuum chamber 17
An opening is formed in the vacuum chamber 16, and the processing target disk substrate 2 mounted on a grounded substrate holder 19 is held in the opening. The electrode vacuum tank 17 and the vacuum tank 16 are evacuated to a vacuum by an exhaust mechanism connected via the valve 4. Further, 7 is a high-frequency voltage applying device, which is connected to the electrode vacuum chamber 17. Reference numeral 8 denotes a gas introduction mechanism, which supplies a gas necessary for plasma processing into the electrode vacuum chamber 17.

[0005]

In the continuous plasma processing apparatus using the above-mentioned conventional technique, the self-bias voltage generated when the substrate 2 is set to the ground potential and the film forming speed are as follows. Compared to those values generated during processing, it is about ⅓, and the film formation rate is at most 0.
It is about 5 nm / s. Further, the etching rate is also slow when the etching process is performed instead of the film forming process. Therefore, when performing a large number of continuous treatments, there is a problem that the time required for film formation or etching becomes a bottleneck and the plasma treatment cannot be performed within the desired time, resulting in poor production efficiency.

[0006] This is mainly due to the grounded substrate 2 surface to be processed and the electrode member (electrode vacuum chamber 17) which is connected to the voltage supply source side and which can surround the space where plasma is generated. It is to be limited by the electric capacity (hereinafter referred to as the floating electric capacity) generated in parallel by the electrode member connected to the voltage supply source side and the spacer between the members grounded. That is, the floating capacitance value is larger than the capacitance of the sheath when plasma is generated.

Therefore, the problem to be solved by the present invention is to solve the problem of plasma generation during plasma processing.
An object of the present invention is to provide an improved plasma processing apparatus having an electrode structure capable of reducing the floating electric capacitance value with respect to the electric capacitance of the plasma.

[0008]

In order to solve the above problems, in the plasma processing apparatus according to the present invention, the vacuum chamber itself that can surround the space above the surface to be processed of the grounded substrate is the power supply side (voltage By using the electrode connected to the supply means), the structure in which the stray capacitance between the power source side member and the grounding member is not generated in the vacuum chamber, which has been pointed out as a conventional problem, is generated as much as possible.

That is, a typical structure thereof is a vacuum container, an exhaust means for maintaining the pressure in the vacuum container at a pressure lower than the atmospheric pressure, an electrode for generating plasma in the vacuum container, and a voltage for the electrode. Voltage supply means for applying,
In a plasma processing apparatus comprising a means for supplying a gaseous substance to a plasma generating part, the vacuum container is a vacuum chamber having a shape capable of surrounding a space where plasma is generated, and the vacuum container is not grounded. A plasma processing apparatus comprising an electrode vacuum chamber which is connected to a voltage supply means and serves as an electrode for generating the plasma, and a ground member in the vacuum container is composed of a substrate and a mounting member thereof. ..

Generally, the gas pressure for plasma treatment is about 0.01 to 0.1 Torr, and in such a gas pressure, the sheath distance generated on the substrate is 5 to 10 m.
m. On the other hand, in the vacuum chamber, the distance between the electrode member and the ace shield surrounding the electrode member must be usually 3 mm or less so that unnecessary plasma is not generated. Further, in the positive bias electrode, the electrode ratio is as follows: power supply side: ground electrode side (substrate side) = 2: 1
The above is necessary. When we think about capacitance here,
When the electrode cross section is A (m ² ), the electrode distance L (m), the vacuum permittivity ε ₀ (F · m ~ ¹ ), and the relative permittivity ε s, the following equation (1)
It is represented by.

[0011]

[Number 1] _{C = ε 0 · εs A /} L ... (1) Therefore, sheet - the electric capacity generated by the scan, A -
The stray capacitance generated in the shield has a larger value.

FIG. 1 shows an equivalent circuit diagram of the electrode in consideration of these points. Here, the electric capacitance C _P (F) generated by the sheath, the floating electric capacitance C _F (F) generated in parallel with the electrodes, the electric capacitance C _A (F) between the electrodes, and the self-bias voltage V _P ( V), space charge current I (A), angular velocity ω
(Rad / s), the floating capacitance C _F (F) is 10 C _{P with} respect to the capacitance C _P (F) in the plasma case.
It can be seen that the value is (F) or more. Therefore, the following equations (2) and (3)

[0013]

[Equation 2] C _P << C _F (2)

[0014]

## EQU3 ## C _A = C _P + C _F ≈C _F (3), and 90% or more of the total electric capacitance C _A between the electrodes is due to the floating electric capacitance C _F. Therefore, the voltage value V _P (self-bias voltage) between the electrodes is calculated by the following equation (4)

))

## EQU4 ## V _P = I / ωC _F (4), which is rate-controlled by C _F.

The plasma processing apparatus according to the present invention has a structure in which the stray capacitance C _F is minimized in consideration of these points. That is, normally, an earth shield is provided on an electrode on the power supply side capable of enclosing plasma in the vacuum chamber to prevent abnormal discharge. However, in the present invention, the vacuum chamber itself is an electrode on the power supply side (vacuum chamber and electrode). The electrode shield tank also serves as an electrode vacuum tank, which eliminates the ground shield inside the vacuum tank and provides an earth cover for surrounding the vacuum tank for safety outside the vacuum tank. These will be specifically described in the following examples.

[0017]

According to the present invention, the bias voltage value can be increased in the electrode structure in which the disk substrate 2 is grounded and a positive bias voltage value is obtained. The experimental results are shown in FIG. Here, the abscissa plots the stray capacitance C _F , and the ordinate plots the bias voltage V _P. As can be seen from the figure, the result is that the bias voltage increases as the stray capacitance C _F decreases. In particular, C _F = 250 (pF)
Below, the desired bias voltage value 800
(V) The above was obtained.

Further, in FIG. 3, the film formation rate is plotted on the vertical axis, and the reciprocal relation between the stray capacitance C _F and the film formation rate is obtained here as well. It is considered that this is because the energy of the ions jumped in by increasing the bias voltage was increased, and the film formation rate was improved.

Further, the vacuum chamber 16 of the conventional apparatus shown in FIG.
Since the earth cover 3 is removed, no abnormal discharge occurs between the electrode on the power supply side and the ground shield, and the plasma leakage, which is a fatal problem in the conventional structure, is completely eliminated. Can be eliminated.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. <Embodiment 1> FIG. 4 is a schematic cross-sectional view of an essential part showing a structural example in which the present invention is applied to a plasma processing apparatus for a disk substrate. That is, the plasma processing apparatus according to the present invention is a vacuum chamber that can be evacuated to a pressure of at least atmospheric pressure or less, and an electrode vacuum chamber 1 that also serves as an electrode for applying a high voltage and a vacuum chamber, and A disk substrate 2 to be processed, which is grounded via a substrate holder, and an array of disks which can surround them.
Scuba-3, an insulating material 5 for insulating them and maintaining a vacuum, a voltage applying device 7 for applying a high voltage to the electrode vacuum chamber 1, and for introducing a gaseous substance into the plasma generation region. Gas introduction mechanism 8, an exhaust mechanism 6 for keeping the inside of the electrode vacuum chamber 1 at atmospheric pressure or below, and a valve 4 for partitioning the electrode vacuum chamber 1 and the exhaust mechanism 6.

When high frequency plasma is generated using such an electrode, a large drop in bias voltage occurs in the substrate of the disk substrate 2, and reactive ion etching is possible if an etching gas is introduced as a gaseous substance from the gas introduction mechanism 8. After the treatment, for example, a film-forming treatment gas such as a methane gas is introduced to form a film-forming treatment such as a hard carbon film.

<Embodiment 2> In FIG. 5, two electrode vacuum chambers 1 shown in FIG. 4 are used with the disk substrate 2 to be processed facing each other. At this time, by independently controlling the gas pressure and gas flow rate of the two plasma processing units, the applied voltage and the current, etc., the difference in processing efficiency between the two plasma processing units (deposition rate, film quality, etching rate, etc.) Is minimized,
A uniform plasma treatment can be performed on both sides simultaneously.

Further, by setting the processing conditions of these two plasma processing sections independently, one processing section performs film formation by, for example, CVD, and the other processing section performs etching processing, or both are processed by CVD. It is possible to combine various treatments, such as different conditions of film formation, for example, film formation of different materials, and desired plasma treatment can be performed simultaneously on both surfaces.

In the structure of the electrodes used in this embodiment, a pair of electrode vacuum chambers 1 facing each other are reciprocated in the vertical direction with respect to the substrate surface of the disk substrate 2 as shown by the arrow. It is used to close the plasma near the substrate 2 or to open the substrate 2 away from the substrate in order to carry it in and out, and is used for sputtering film formation, plasma CVD, etc., and also for plasma etching treatment, etc. be able to.

As described above, the reciprocating mechanism of the electrode vacuum chamber 1 is used when loading / unloading the disk substrate 2 into / from the apparatus main body. Specifically, the electrode vacuum chambers 1 facing each other are to be processed. Keep away from the portion 18 and the disk substrate 2
After being set on the processed portion 18, the electrode vacuum chamber 1 is brought closer to both sides of the disk substrate 2 to a distance where plasma does not leak, and a high voltage is applied from the power supply 7 to generate plasma. After the processing, the plasma is stopped, the electrode vacuum chamber 1 is moved away from the disk substrate 2 again, and the disk substrate 2 is discharged.

<Third Embodiment> FIG. 6 shows an example of a magnetic disk manufacturing apparatus to which the present invention is applied. In this apparatus, a disk substrate 2 is mounted on a holder 19, and the holder 19 is placed on a rail 15 to be conveyed, and a preparation chamber 9, a pretreatment chamber 10 and a sputtering chamber 1 are provided.
1 (composed of two chambers 11a and 11b in this example), a partition chamber 12, a plasma CVD chamber 13, and a take-out chamber 14 in this order, and a base film, a magnetic film, and a protective film are formed in this order and taken out. .. Rails 15 are continuously laid in each of these chambers so that the substrate can move in each chamber.

In this embodiment, the pretreatment chamber 10 is
Although it may be simply heated, it has the same structure as the plasma CVD chamber 13, and the gas introduction mechanism 8 (see FIGS. 4 and 5) to C
Instead of the VD gas, an inert gas such as argon may be introduced to generate plasma to lightly etch the substrate surface. That is, in this case, the plasma processing apparatus of the present invention is applied to the processing chamber 10 as an etching processing apparatus.

Next, an example of actually manufacturing a magnetic disk using the above apparatus will be described. Twenty sets of disk substrates 2 each having a diameter of 5.25 inches mounted on a holder 19 were set in the preparation chamber 9 and evacuated.
In the sputtering cathode of the sputtering chamber 11, a pair of a Cr target for a base film and a CoCrTa alloy target for a magnetic film were set in advance, and after vacuum evacuation, argon was introduced and the gas pressure was kept at 10 mTorr. DC plasma was generated, dummy sputtering was performed for 1 to 2 hours, and then the plasma was stopped. Next, the holder-19 is conveyed toward the side of the single take-out chamber 14 and
When it reached the pretreatment chamber 10, it was once stopped and heated to heat the substrate to about 200 ° C.

Next, the holder was conveyed to the sputtering chamber 11, and at the same time, the next holder was sent from the charging chamber 9 to the pretreatment chamber 10. In this way, the holder 19 was sequentially sent out while performing processing in each processing chamber. In this way, about 300 nm of Cr was sputtered on the disk substrate in the sputtering chamber 11a, and then CoCrTa alloy of 50 nm was sputtered in the sputtering chamber 11b. Then, it was transported to the plasma CVD chamber 13.

As shown in FIG. 5, during the transportation, the inside of the processing tank is evacuated in advance, and the electrode vacuum tank 1 is moved away from the disk substrate 2. Secured an easy passage. When the holder 19 reaches the processing target 18 and stops, the electrode vacuum chamber 1 is moved toward the disk substrate surface to reduce the distance between the processing target 18 and the electrode vacuum chamber 1 and the holder 19. Narrowed the intervals. Then, methane (CH ₄ ) gas was introduced from the gas introduction mechanism 8 and the flow rate and the exhaust speed were adjusted so that the pressure became constant at 6.7 (Pa). Then, a high voltage having a frequency of 13.56 MHz was applied to generate plasma. At this time, the effective power is 1 kW and the bias voltage is 1
000 (V) was obtained, and the film formation rate was 1 nm / s. After holding the plasma for 1 minute, stop the voltage application,
The electrode vacuum chamber 1 was moved away from the disk substrate 2 again, the gas was stopped and the gas was exhausted. Then, the disk substrate holder 19 was sent to the take-out chamber 14, and at the same time, the next disk substrate 2 was introduced.

By repeating the above cycle, 2
A hard carbon protective film was formed on the disk substrate 2 mounted on 0 holders 19. At this time, when the protective film thickness of 20 nm required on the disk substrate is 1 nm / s
Since it was obtained, the execution processing time was about 20 s, which was able to be shortened to about 1/3 of the conventional case.

<Embodiment 4> FIG. 7 is a partially cutaway sectional perspective view of a magnetic disk device in which a plurality of magnetic disks 21 manufactured by using the plasma processing apparatus of Embodiment 3 are mounted on a spindle. is there. As shown, the magnetic disk device includes a magnetic head 21, a magnetic disk 20,
The magnetic head 21 is attached to the magnetic disk 21 via the arm 22.
2 for moving to a predetermined position within the effective recording / reproducing range of
5 and an access mechanism (not shown) for writing or reading information on the magnetic disk 20 via the magnetic head 21. In this device, good results comparable to the durability of the conventional carbon protective film were obtained.

<Fifth Embodiment> In this embodiment, the plasma processing apparatus of the first embodiment is applied to an etching apparatus to form a gate electrode array of a field effect transistor of a liquid crystal display device. First, as the substrate 2, a glass substrate on which aluminum was vapor-deposited or sputtered beforehand, and a predetermined resist mask pattern was formed thereon by a well-known lithographic technique was prepared. Next, a commercially available fluorine-based gas was introduced as an etching gas from the gas introduction mechanism 8, and the substrate 2 was subjected to plasma etching treatment under substantially the same plasma generation conditions as the carbon film formation in Example 3. As a result, an aluminum etching pattern corresponding to a predetermined mask pattern was obtained, and the intended aluminum gate electrode array could be formed. The etching rate was about 3 times faster than the conventional one, and the processing accuracy was comparable to the conventional one.

[0034]

As described above, according to the present invention, the intended purpose can be achieved. That is, plasma C
In the VD positive bias electrode structure, the factor limiting the bias voltage value was eliminated, and the value could be increased.
Therefore, the energy of ions jumping to the surface of the substrate to be processed can be increased, the chemical reaction on the surface can be promoted, and film formation or etching speed can be increased. Therefore, for example, a large number of disc substrates can be sequentially transported to provide an efficient processing apparatus in a short time, and the applicable range of the multi-step continuous processing apparatus can be greatly expanded.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram of a plasma CVD electrode structure for explaining a floating capacitance.

FIG. 2 is a characteristic curve diagram showing a relationship between a floating capacitance and a bias voltage value.

FIG. 3 is a characteristic curve diagram showing the relationship between floating capacitance and film formation rate.

FIG. 4 is a cross-sectional view showing the basic configuration of an embodiment of a plasma processing apparatus according to the present invention.

FIG. 5 is a sectional view of a plasma processing apparatus according to another embodiment of the present invention.

FIG. 6 is a sectional view of a continuous plasma film forming apparatus according to another embodiment of the same.

FIG. 7 is a partially cutaway perspective view of a magnetic disk device equipped with a magnetic disk manufactured by using the plasma processing apparatus of the present invention.

FIG. 8 is a cross-sectional view showing the configuration of a conventional plasma processing apparatus.

[Explanation of symbols]

1 ... Electrode vacuum tank, 2 ... Disk substrate to be processed, 3 ... Aer cover,
4 ... Valve, 5 ... Insulation material,
6 ... Exhaust mechanism, 7 ... Voltage applying mechanism,
8 ... Gas introduction mechanism, 9 ... Preparation room,
10 ... Pretreatment chamber, 11 ... Sputtering chamber,
12 ... Partition chamber, 13 ... Plasma CVD processing chamber, 14 ... Take-out chamber, 15 ... Rail,
16 ... Vacuum tank, 17 ... Electrode vacuum tank,
18 ... Processed part, 19 ... Substrate holder,
20 ... magnetic disk, 21 ... head,
22 ... Arm, 23 ... Spindle motor, 24 ... Cover, 25 ... Mechanism for moving the magnetic head to a predetermined position within the effective recording / reproducing range of the magnetic disk.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryo Kito, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd.

Claims (11)

[Claims] 1. A vacuum container, an evacuation means for keeping the pressure in the vacuum container lower than atmospheric pressure, an electrode for generating plasma in the vacuum container, and a voltage supply for applying a voltage to the electrode. In a plasma processing apparatus comprising means and means for supplying a gaseous substance to a plasma generating part, the vacuum container is a vacuum chamber having a shape capable of enclosing a space in which plasma is generated, and the vacuum container is grounded. A plasma processing apparatus which is constituted by an electrode vacuum chamber which is connected to a voltage supply means without being used as an electrode for generating the plasma, and in which the ground member in the vacuum container is constituted by a substrate and its mounting member. 2. A plasma processing apparatus having a structure in which a pair of the electrode vacuum chambers are arranged on both sides of a substrate to be plasma-processed so as to face each other, and both surfaces of the substrate can be independently plasma-processed. 3. An electrode vacuum chamber moving means for mutually reciprocating the set of electrode vacuum chambers in a direction perpendicular to the substrate surface of the plasma processed substrate; and discharging the substrate out of the electrode vacuum chamber. The plasma processing apparatus according to claim 1 or 2, further comprising: a substrate moving unit that conveys the substrate. 4. The plasma processing apparatus according to claim 1, wherein an earth cover is provided in the atmosphere outside the vacuum container. 5. The plasma processing apparatus according to claim 1, wherein the electric capacity generated between the electrode vacuum chamber and the substrate holder including the substrate is 250 pF or less. 6. The plasma processing apparatus according to claim 1, wherein the electrode vacuum tank is a plasma CVD processing tank. 7. The plasma processing apparatus according to claim 1, wherein the electrode vacuum tank is a plasma etching processing tank. 8. A method of manufacturing a magnetic disk, comprising a step of forming a protective film on a surface of a magnetic disk substrate on which a magnetic film is formed by a plasma CVD process, wherein the plasma generating unit of the plasma processing apparatus according to claim 1, A method of manufacturing a magnetic disk, comprising forming a predetermined protective film by supplying a predetermined protective film forming gas as a gaseous substance. 9. A method of manufacturing a magnetic disk according to claim 8, wherein a hydrocarbon gas is supplied as the predetermined protective film forming gas to form a carbon protective film. 10. A magnetic disk comprising a protective film formed by the method for manufacturing a magnetic disk according to claim 8. 11. A magnetic head, a magnetic disk, a mechanism for moving the magnetic head to a predetermined position within an effective recording / reproducing range of the magnetic disk via an arm, and a magnetic disk to the magnetic disk via the magnetic head. A magnetic disk device comprising an access mechanism for writing or reading information, wherein the magnetic disk is a magnetic disk device.
A magnetic disk device comprising the magnetic disk described in 0.