Patent Application
20150329968
The present invention relates to a plasma CVD apparatus for forming a CVD coating on a substrate, and more particularly, to an in-line plasma CVD apparatus with a high production efficiency while maintaining stable deposition conditions.
Engine parts, etc., of automotives, such as a piston ring, are required to have good wear resistance, heat resistance, seizure resistance, and the like. For this reason, these mechanical parts are subjected to a wear-resistant coating, such as a diamond-like-carbon (DLC), by using a plasma CVD method.
When forming the coating on the above-mentioned substrate by the plasma CVD method, numerous substrates are preferably accommodated in a vacuum chamber and coated at one time in terms of productivity. In order to process the numerous substrates at one time in this way, the coatings formed on the respective substrates have to have uniform thickness and film properties among the substrates. Thus, in a conventional plasma CVD apparatus, a plurality of substrates is arranged on the same table. The substrates undergo the deposition process while being rotated and revolved by driving the table.
Alternatively, from another viewpoint of improving the productivity, a so-called in-line type apparatus, or an apparatus equipped with a load-lock chamber is employed. Such an apparatus includes a deposition chamber, and a chamber dedicated to evacuation or the like and separately provided from the deposition chamber. The substrates are conveyed between these chambers. In this way, a number of deposition cycles are performed with the deposition chamber constantly maintained under vacuum.
Japanese Unexamined Patent Application Publication No. H5-295551 (Patent Document 1) discloses a modified technique for an in-line plasma CVD apparatus that deposits a coating on a surface of an object to be processed (substrate, base) by the plasma CVD method. FIG. 2 in Patent Document 1 discloses a typical example of the in-line plasma CVD apparatus in the related art. Referring to
In the in-line plasma CVD apparatus, the respective stages of the process are performed in compartments independent from each other. Thus, the in-line plasma CVD apparatus can be expected to have high productivity, and to stably form a coating of high quality with no gaseous adsorption in the inside of the deposition chamber while not needing exposure of the deposition chamber to the atmosphere every time each substrate is inserted into the deposition chamber. Note that Patent Document 1 discloses the technique of the in-line plasma CVD apparatus in which an atmospheric heating furnace is provided to preheat the substrate under atmospheric pressure, thereby shortening a temperature rise time for increasing the temperature of the substrate up to a predetermined temperature in the load chamber.
In apparatuses that form a coating by the plasma CVD method, the coating is deposited not only a substrate to be coated, but also walls of a deposition chamber, electrodes facing the substrate, and the like. In particular, a part serving as an electric current passage for generating a plasma tends to be covered with the coating. The substrate to be coated and a jig supporting the substrate are removed after completion of the deposition process, and then the substrate is replaced by a next object to be coated. However, the walls of the deposition chamber and the electrodes or the like facing the substrate are used through multiple processes, so that the coating deposited thereon becomes thicker as the deposition cycle is repeated.
For example, in the deposition apparatus disclosed in Patent Document 1, while a high-frequency electrode denoted by reference numeral 30 in FIG. 2 of Patent Document 1 is opposed to the substrate mounted on a substrate cart denoted by reference numeral 1, a plasma is generated by applying a high-frequency power to the high-frequency electrode. Thus, the coating is formed on the substrate and simultaneously the coating is also deposited on the high-frequency electrode in the substantially same amount as that of the coating on the substrate. Although the substrate cart and the substrate are replaced by new ones every completion of the deposition cycle, the high-frequency electrode is constantly used, so that the coating is continuously deposited on the electrode. The coating deposited thick in this way tends to be peeled off and fly apart, which can result in a defective coating. Such deposits therein need to be removed by cleaning on a regular basis.
Further, when the coating deposited by the plasma CVD method is an insulating coating, such as a DLC, other problems can also be caused. That is, as the deposition progresses to thicken the coating, the insulating coating can include a resistance component acting on supply of electric power. Thus, even if the same power conditions are set, the state of generation of the plasma disadvantageously fluctuates, and thus the properties of the coating are also varied.
As another system of the plasma CVD apparatus, there is proposed a system in which a part of the high-frequency electrode is simply a wall of a chamber and an electric power is applied to a substrate and a substrate cart. Even in this system, however, the coating is also deposited on the chamber wall opposed to the substrate as well as on the substrate. As a result, there arises a problem that the deposits attached thickly might fly apart. When the formed coating is insulating, the coating positioned even on the chamber side exist at the part through which the electric power passes, resulting in an increase in electric resistance of the inner wall of the chamber. Thus, the generation of the plasma that would occur with an inner wall of the chamber serving as one electrode becomes unstable, or process requirements can deviate from the optimal ones.
Patent Document 1: JPH 05-295551 A
Accordingly, it is an object of the present invention to provide an in-line plasma CVD apparatus with a high production efficiency that is less likely to deposit a CVD coating on a part other than a substrate, thereby being capable of stably performing its operation without cleaning for a long time.
The in-line plasma CVD apparatus provided by the present invention includes a deposition chamber and a compartment other than the deposition chamber. A substrate is conveyed between the deposition chamber and the compartment. The deposition chamber includes a vacuum chamber, a pump for exhausting the air from the vacuum chamber, a gas supply unit for supplying a source gas into the vacuum chamber, and an AC plasma generation power supply for generating a plasma in the source gas supplied into the vacuum chamber. In the deposition chamber, the substrates are divided or classified into two groups. Specifically, the substrates belong to either a first group which is connected to one pole of the plasma generation power supply, or a second group which is connected to the other pole of the plasma generation power supply.
Now, some embodiments of an in-line plasma CVD apparatus 100 according to the present invention (hereinafter simply referred to as a “plasma CVD apparatus 100”) will be described in detail based on the accompanying drawings. Here, the term “in-line type” as used herein is a generic name for an apparatus system with a mechanism that includes a load-lock chamber (pre-evacuation chamber). The mechanism constantly maintains a deposition chamber in a vacuum state, also at the time of replacement of substrates, by exchanging the substrate between an area outside the apparatus (atmospheric pressure) and the deposition chamber (vacuum pressure) via the load-lock chamber. The in-line type includes a load-lock type, an inter-back type, and a multi-chamber type. The object to be coated by the plasma CVD apparatus 100 is a substrate W.
The plasma CVD apparatus 100 includes a deposition chamber 1 with a plasma CVD mechanism, a load-lock chamber 20 which is another compartment disposed on an upstream side of the deposition chamber 1, and a load-lock chamber (compartment) 30 which is a further compartment disposed on a downstream side of the deposition chamber 1. The terms “upstream” and “downstream” as used herein are based on the transport direction of the substrate W. At an inlet of the load-lock chamber 20, an isolation valve 41 is placed. An isolation valve 42 is placed between an outlet of the load-lock chamber 20 and an inlet of the deposition chamber 1. An isolation valve 43 is placed between an outlet of the deposition chamber 1 and an inlet of the load-lock chamber 30. An isolation valve 44 is placed at an outlet of the load-lock chamber 30.
These isolation valves 41 to 44 are closed, whereby the deposition chamber 1, the load-lock chamber 20, and the load-lock chamber 30 are interrupted from the adjacent chamber or atmosphere. That is, by closing the isolation valve, the transfer of the atmosphere or the pressure can be interrupted between the adjacent chambers. On the other hand, by opening the isolation valve, the substrate W independently, or the substrate W mounted on the substrate table can be transported between the adjacent chambers.
The substrates W are divided into two groups. In at least the deposition chamber 1, a vacuum chamber 2 to be described later is grounded, so that both the groups are insulated from the vacuum chamber 2, and are also insulated from each other. Therefore, the respective groups can have potentials independent from each other. These will be described in detail below.
The load-lock chamber 20 includes the isolation valve 41 serving as a door for carrying in the substrate W, and an evacuation mechanism. While the isolation valve 41 is opened (with the isolation valve 42 closed at this time) and exposed to the atmosphere, the substrates W and the substrate table are carried from the outside of the plasma CVD apparatus 100 into the load-lock chamber 20. Thereafter, the isolation valve 41 is closed (with the isolation valve 42 kept closed at this time), so that the inside of the load-lock chamber 20 can be exhausted to vacuum. Once a pretreatment including heating is completed with the inside of the load-lock chamber 20 being under vacuum, then the isolation valve 42 located between the load-lock chamber and the deposition chamber 1 previously evacuated is opened (with the isolation valves 41 and 43 closed at this time), and the substrates W and the substrate table are transported to the deposition chamber 1 under vacuum. The plasma CVD apparatus 100 includes a transport mechanism for transporting the substrates W and the substrate table between the chambers.
After completion of the transport, the isolation valve 42 is closed, followed by introducing the atmospheric air into the load-lock chamber 20, so that the inside of the load-lock chamber 20 is at atmospheric pressure. In this way, substrates W of a next lot and another substrate table can be received.
As shown in
The load-lock chamber 30 includes the isolation valve 44 serving as a door for carrying out the substrate W, and an evacuation mechanism. After the inside of the load-lock chamber 30 is exhausted to vacuum with the isolation valve 44 closed, the isolation valve 43 is opened, whereby the substrate W on which the coating is formed under vacuum in the deposition chamber 1 and the substrate table can be carried from the deposition chamber 1 into the load-lock chamber 30. Then, the isolation valve 43 is closed, so that the deposition chamber 1 is brought into a standby state for the carry-in operation of the substrate W and the substrate table from the load-lock chamber 20 again.
After the isolation valve 43 is closed, a postprocessing including cooling is performed with the load-lock chamber 30 being under vacuum. If the postprocessing is completed, then the atmospheric air is introduced into the load-lock chamber 30. Once the inside of the load-lock chamber 30 reaches the atmospheric pressure, the isolation valve 44 is opened (with the isolation valve 43 closed at this time). In this way, the substrates W and the substrate table, which are exposed to the atmosphere, are carried from the load-lock chamber 30 out to the outside of the plasma CVD apparatus 100. The plasma CVD apparatus 100 includes the transport mechanism for transporting the substrates W and the substrate table between the chambers.
Thereafter, the isolation valve 44 is closed and the inside of the load-lock chamber 30 is exhausted to vacuum. In this way, the load-lock chamber 30 is brought into a state capable of receiving a next substrate W of another lot and another substrate table therefor from the deposition chamber 1.
The above-mentioned structure of the plasma CVD apparatus 100 according to the first embodiment is the same as that of the normal so-called in-line deposition apparatus except that an AC power is applied to the substrates W divided into two groups, which is the feature of the present invention as will be described later. Thus, the plasma CVD apparatus 100 also has the advantages, which are general merits of the in-line deposition apparatus, specifically, that there are few chances for the deposition chamber to be exposed to the atmosphere, enabling the stable coating, and that the mass production can be achieved because of a short tact time. In addition, the plasma CVD apparatus 100 has overcome disadvantages of the general in-line deposition apparatus by refining the structure of the deposition chamber 1. Specifically, the disadvantages are that the deposition chamber 1 sandwiched between the load-lock chamber 20 and the load-lock chamber 30 has to be purposely exposed to the atmosphere in order to clean or remove the coating deposited on the inner wall surface of the deposition chamber 1 that is hardly exposed to the atmosphere. Next, a description will be given of the detailed structure of the deposition chamber 1 in the plasma CVD apparatus 100.
The structure of the deposition chamber 1 in the plasma CVD apparatus 100 will be described below using
The vacuum chamber 2 is a casing capable of having its internal space sealed from the outside air. The vacuum pump 3 is provided on a side surface of the vacuum chamber 2, and serves to exhaust gas from the vacuum chamber 2 into the outside environment to bring the inside of the vacuum chamber 2 into a low-pressure state. The vacuum pump 3 can decompress the inside of the vacuum chamber 2 into the vacuum state.
The plasma CVD apparatus 100 further includes the substrate table. The substrate table is capable of mounting a plurality of substrates W thereon, so that these substrates W can be processed within the vacuum chamber 2 while being mounted on the substrate table. The substrate table has a mechanism that performs planetary rotation, that is, rotation and revolution of the substrate W mounted on the substrate table. Specifically, as shown in
The substrate table can be transported using a table trolley 50. The table trolley 50 is a transportation mechanism for transporting the substrates W together with the substrate table, and includes a plurality of wheels 51. The substrate table can horizontally move within the plasma CVD apparatus 100, while being mounted on the table trolley 50. The table trolley 50 in the first embodiment is sequentially moved from the outside of the plasma CVD apparatus 100 to the load-lock chamber 20, from the load-lock chamber 20 to the deposition chamber 1, from the deposition chamber 1 to the load-lock chamber 30, and from the load-lock chamber 30 to the outside of the plasma CVD apparatus 100.
While the table trolley 50 is stopped at the center of the deposition chamber 1, a rotation introducing mechanism provided under the deposition chamber 1 is connected to the table trolley 50. The rotation introducing mechanism includes a shaft 14 and a rotation driving portion 15 as shown in
The substrate W subjected to deposition by the plasma CVD apparatus 100 of the first embodiment is preferably installed in a cylindrical space elongated vertically so as to enable the uniform deposition. For example, if the substrate W is a piston ring shown in
When the substrates W to be coated are small-sized members (for example, small piston pins) as shown in
Even when the substrate W has a shape other than the above-mentioned shape, preferably, a fixing jig corresponding to the shape may be manufactured as appropriate, and the jig and the substrates may be accommodated in the cylindrical space.
An assembly of the substrates W shown in
The rotation table 4 is, for example, a circular mounting stand having a flat upper surface. The rotation table 4 holds the substrate W disposed on its upper surface or at an upper part thereof while rotating the substrate W on its rotary axis. The rotation table 4 can be power-fed, and the voltage supplied is also applied to the substrates W.
The substrate table of the plasma CVD apparatus 100 shown in FIGS. 1, 2, and 4B includes six rotation tables 4 in total. These six rotation tables 4 are disposed on the revolution table 5 so as to be arranged on one circle in the planar view.
On the other hand, as shown in
For example, when a carbon-based CVD coating, such as a DLC (diamond-like-carbon, amorphous carbon film), is deposited, a source gas including a carbon hydride (acetylene, ethylene, methane, ethane, benzene, toluene, etc.) is used as a process gas. Further, an inert gas, such as argon or helium, may be added as an assist gas as needed. When a silicon oxide-based CVD coating (e.g., SiOx film, SiOC film, SiNx film, SiCN film) is deposited, a reaction gas, such as oxygen, nitrogen, or ammonia, is added to the source gas containing silicon, such as a silicon organic compound (monosilane, TMS, TEOS, HMDSO etc.), or silane. Further, an inert gas, such as argon, can be added as an assist gas in use as needed. The CVD coatings can include, in addition to those described above, a TiOx film, an AlOx film, an AlN film, and the like.
A small amount of an additional source gas is sometimes mixed into the main source gas. For example, when forming the DLC coating, a small amount of a silicon-based organic compound gas is added to the source gas mainly containing carbon hydride, so that a coating containing Si can be formed in the DLC. Alternatively, when forming the DLC coating, a small amount of the source gas containing metal (e.g., TTIP (titanium isopropoxide), TDMAT (tetrakis(dimethylamino) titanium)) is added to the source gas mainly containing carbon hydride, so that a coating containing metal (e.g., titanium) can be formed in the DLC.
These source gas, reaction gas, and assist gas can be used in combination as appropriate, depending on the kinds of the gases used.
Now, a description will be given of the characteristic structure of the deposition chamber 1 of the plasma CVD apparatus 100 in the first embodiment, specifically, the plasma generation power supply 10, as well as the supply of power from the plasma generation power supply 10 to the substrate W.
The plasma generation power supply 10 is used to generate the glow discharge in the process gas supplied into the vacuum chamber 2, thereby producing a plasma. The plasma generation power supply 10 supplies an AC power. Examples of the AC power supplied by the plasma generation power supply 10 may include not only an AC power that changes a current or voltage positively and negatively according to a sine waveform, but also an AC power with a square wave that switches between the positive and negative according to a pulsed waveform. The AC for use can also be one including alternating continuous pulse groups with the same polarity, or one formed by superimposing the square wave on the sine-wave AC. In fact, a voltage waveform during generation of the plasma is sometimes distorted due to the influence of the generated plasma. Once the plasma is generated, the zero level of the AC voltage is shifted. When the potential with respect to the ground potential of each electrode is measured, it is observed in many cases that 80 to 95% of the applied voltage is assigned to the negative electrode, and 5 to 20% of the applied voltage is assigned to the positive electrode.
The frequency of the AC current supplied from the plasma generation power supply 10 is preferably in a range of 1 kHz to 100 MHz. When the frequency of the AC current is less than 1 kHz, the charge-up of the coating tends to occur. On the other hand, when the frequency of the AC current exceeds 100 MHz, it is difficult to execute the electric-power feed to the inside of the chamber. In particular, the frequency is preferably in a range of 10 kHz to 400 kHz from the viewpoint of easiness to supply the power to the substrate W, further availability of the power supply, and the like. Especially, when there is provided a rotation and revolution mechanism of the substrate W, the frequency of the AC current is preferably in a range of 1 kHz to 1 MHz. When the frequency is less than 1 kHz, the charge-up of the coating tends to occur. Further, it is difficult to establish a mechanism that transmits the power with a frequency of more than 1 MHz, to the rotating and revolving substrate W. Taking into consideration the availability of the power supply or the like, the frequency of the AC current is more preferably in a range of 10 kHz to 400 kHz. An AC voltage supplied from the plasma generation power supply 10 is preferably in a range of 300 to 3000 V required for maintaining the glow discharge as a wave crest value. The AC power supplied from the plasma generation power supply 10 is varied depending on a superficial area of the substrate W. However, a power per unit area preferably has a power density of about 0.05 to 5 W/cm2.
A glow discharge is generated between the electrodes by applying the AC current with the frequency, voltage, and power (power density) described above to between a pair of electrodes disposed in the vacuum chamber 2. The generated glow discharge decomposes a process gas supplied into the vacuum chamber 2, thereby generating a plasma. Then, the gas components produced through decomposition by the plasma are deposited on the surface of each electrode, thereby depositing a CVD coating. That is, the use of the substrate W as either of a pair of electrodes can deposit the CVD coating on the surface of the substrate W.
As shown in
Specifically, when the six rotation tables 4 in total are disposed on the revolution table 5, the three rotation tables 4 among the rotation tables 4 designated by “A” in
Specifically, as to these rotation tables 4, the rotation tables 4 belonging to the second group 19 are provided on both sides of the rotation table 4 belonging to the first group 18. Further, another rotation table 4 belonging to the first group 18 is provided adjacent to the rotation table 4 belonging to the second group 19. That is, the rotation tables 4 belonging to the first group 18 and the rotation tables 4 belonging to the second group 19 are arranged one by one in alternate order (alternately) around a revolution axis Q of the revolution table 5.
The plasma generation power supply 10 has a pair of electrodes. All three rotation tables 4 belonging to the first group 18 are connected to one electrode of the plasma generation power supply 10. All three rotation tables 4 belonging to the second group 19 are connected to the other electrode of the plasma generation power supply 10. That is, during application of the voltage, the rotation table 4 belonging to the first group 18 has constantly a polarity reverse to that of the rotation table 4 belonging to the second group 19.
The above-mentioned polarities are imparted to the respective rotation tables 4, for example, by providing a brush mechanism (not shown) in each of the revolution axis Q and a rotation axis P, and applying voltages with the respective polarities to the revolution axis Q and the rotation axis P through the brush mechanisms. The revolution axis Q and the rotation axis P are rotatably held by the bearing mechanism, through which the voltage may be applied thereto.
As shown in
First, the substrates W are set on the rotation tables 4. The substrates W may be directly fixed to the rotation tables 4, or may be installed on the rotation tables 4 via the mounting jig 13. The rotation tables 4 constitute the substrate table together with the revolution table 5. Further, the substrate table is movable within the plasma CVD apparatus 100, while being mounted on the table trolley 50.
(Second Step: Carrying into Load-Lock Chamber 20, and Pretreatment)
After the substrate W is prepared in this way, first, the isolation valve 41 as an inlet door of the load-lock chamber 20 is opened, and then the table trolley 50 with the substrates W mounted thereon enters the load-lock chamber 20. Then, the isolation valve 41 as the inlet door of the load-lock chamber 20 is closed, and the inside of the load-lock chamber 20 is exhausted by the vacuum pump 3 serving as the vacuum exhaust means. Thereafter, the substrate W is preferably heated by a heater within the load-lock chamber 20. In this step, the isolation valve 42 is kept closed. In an example shown in
Next, the isolation valve 42 between the load-lock chamber 20 and the deposition chamber 1 previously evacuated is opened, and the table trolley 50 with the substrates W mounted thereon is moved to the deposition chamber 1. After completion of the movement of the table trolley 50 to the deposition chamber 1, the isolation valve 42 is closed to evacuate the inside of the deposition chamber 1. In addition, in the first embodiment, the rotation mechanism for the substrate table positioned at a bottom part of the deposition chamber 1 is raised to be coupled to the substrate table on the table trolley 50, thereby enabling rotation of the substrate table, and simultaneously causing the substrate table to be electrically connected to the plasma generation power supply 10.
Then, the gas supply unit 9 supplies inert gas, such as Ar, or gas, such as H2 or O2, into the vacuum chamber 2 as needed to generate the glow discharge for cleaning the surface between the substrates W by supplying power from the plasma generation power supply 10 (ion bombardment process).
Thereafter, the gas supply unit 9 supplies the process gas into the vacuum chamber 2, thereby holding the pressure of the vacuum chamber 2 at a pressure of 0.1 to 1000 Pa appropriate for deposition.
In deposition, the glow discharge is generated between the substrates W on the rotation tables 4 belonging to the first group 18 and the substrates W on the rotation tables 4 belonging to the second group 19 by supplying AC power from the plasma generation power supply 10 to the rotation tables 4 belonging to the respective groups 18 and 19, so that a plasma required for deposition is generated between the substrates W.
An appropriate pressure during the deposition process differs depending on the kind of the CVD coating (process gas and reaction gas) to be deposited. In general, the pressure is preferably in a range of approximately 0.1 Pa to 1000 Pa. As mentioned above, the pressure in the deposition of approximately 0.1 Pa to 1000 Pa enables stable generation of the glow discharge, thereby depositing the coating at appropriate deposition rate. Further, the pressure in the deposition is preferably 100 Pa or less from the viewpoint of suppressing formation of powder together with the reaction in gas.
An AC voltage supplied from the plasma generation power supply 10 is preferably in a range of 300 V to 3000 V required for maintaining the glow discharge (as a wave crest value of the voltage between both electrodes). Further, the AC output power supplied from the plasma generation power supply 10 is preferably in a range of about 0.05 to 5 W/cm2 in terms of power per unit area.
After adjusting the voltage and power of the AC current supplied from the plasma generation power supply 10 in this way, the substrate is rotated and revolved every rotation table 4, whereby the stable glow discharge is generated between the substrates W (substrates W close to each other) adjacent in the peripheral direction, which can form the CVD coating with a uniform thickness over the surfaces of the substrates W. During these steps, the isolation valve 42 and the isolation valve 43 are kept closed.
(Fourth Step: Carrying into Load-Lock Chamber 30, and Postprocessing)
When the deposition process is finished, the output from the plasma generation power supply 10 as well as the introduction of the process gas are stopped. Thereafter, the isolation valve 43 located between the deposition chamber 1 and the load-lock chamber 30 on its downstream side which is previously evacuated is opened. The substrates W mounted on the substrate table are transported to the load-lock chamber 30 by moving the table trolley 50, and then the isolation valve 43 is closed. Thereafter, the plasma CVD apparatus is brought into a standby state for a decrease in temperature of the substrate W within the load-lock chamber 30 as needed. Note that in this step, the isolation valve 44 is kept closed.
Then, the atmospheric air, inert gas, or the like is introduced into the load-lock chamber 30. Once the pressure of the load-lock chamber 30 reaches the atmospheric pressure, the isolation valve 44 as an outlet door of the load-lock chamber 30 is opened, and the table trolley 50 with the substrates W mounted thereon departs from the load-lock chamber 30.
In the deposition chamber 1, as mentioned above, the rotation tables 4 of the first group 18 and the rotation tables 4 of the second group 19 which have the reversed polarities to each other are arranged in alternate order (alternately) in the peripheral direction of the table, which generates a potential difference between the substrates W respectively held by the rotation tables 4 adjacent in the peripheral direction. Thus, the glow discharge is surely generated between both substrates. If positive and negative charges of both electrodes are switched in the plasma generation power supply 10, the polarities of the rotation tables 4 adjacent in the peripheral direction are also switched to thereby subsequently generate the glow discharge between both electrodes. Thus, the deposition can be uniformly performed on the numerous substrates W at one time.
That is, when the substrate W on the rotation table 4 belonging to the first group 18 acts as a working electrode, and the CVD coating is deposited on the side of the substrate W, the substrate W on the rotation table 4 belonging to the second group 19 acts as a counter electrode (opposite electrode). Then, when the positive and negative electrodes of the plasma generation power supply 10 are switched, the substrate W on the rotation table 4 belonging to the second group 19 acts as the working electrode, and the substrate W on the rotation table 4 belonging to the first group 18 acts as the counter electrode.
That is, with the structure described above, even though the substrates W serve as the counter electrode, the casings for the revolution table 5 and the vacuum chamber 2 do not serve as the counter electrode. Since they do not act as a discharge generation electrode, these members are not exposed directly to a plasma produced by decomposing the source gas, and thus the coating is less likely to be deposited on these members, as compared to in the related art. As a result, flakes that would cause deposition of a thick coating is less likely to occur, which hardly generates the defective coating. These members do not act as an electrode for generation of the glow discharge so as to generate a plasma. Even if an insulating coating is deposited thickly during the operation for a long time, the generation of the plasma is not made unstable. Therefore, the CVD coating with less variation in film properties and thickness can be also stably produced.
In particular, the deposition chamber 1 of the in-line plasma CVD apparatus is required to process the numerous substrates without being exposed to the atmospheric air. Thus, the structure of the plasma CVD apparatus 100 in the first embodiment is very useful because it does not deposit the thick coating on the casing of the vacuum chamber 2.
The minimum deposition process has been described above. The minimum process includes carrying in the substrate in the atmospheric state, evacuating, heating, deposition by the plasma CVD apparatus, cooling, and carrying out the substrate in the atmospheric state in this order. If necessary, a more complicated deposition process can be achieved by increasing the number of chambers in the plasma CVD apparatus 100 and the like. For example, the plasma CVD apparatus 100 can also include numerous compartments for performing different steps as follows.
1) Load-lock Chamber: Evacuation
2) Heating Chamber: Preheating of Substrate W
3) Pretreatment Chamber: Adhesion Improvement Process Including Etching of Substrate W or the like.
4) Intermediate Layer Deposition Chamber: Formation of Intermediate Layer for Improvement of Adhesion by Sputtering or the like
5) Deposition Chamber: Deposition by Plasma CVD on Substrates Divided into Two Groups
6) Cooling Chamber: Cooling
7) Load-lock Chamber: Exposure to Atmosphere
Also in this case, the structure of the plasma CVD apparatus 100 in the first embodiment can be employed in the “5) deposition chamber” to achieve the stable deposition in the deposition chamber, and a low frequency of maintenance.
Now, a plasma CVD apparatus 200 according to a second embodiment of the invention will be described with reference to
As shown in
The pair of substrate tables are insulated from each other, and also insulated from the vacuum chamber 202. The substrates W on each table constitute respective groups. The deposition chamber 201, the load-lock chamber 220, and the load-lock chamber 230 have the respective size that can accommodate therein the substrate table. In the deposition chamber 201, a plasma is generated between the groups of the substrates W on the substrate tables, thereby depositing a coating on the substrate W.
The substrate table may have a mechanism for planetary rotation of each substrate W as shown in
Now, a plasma CVD apparatus 300 according to a third embodiment of the invention will be described with reference to
As shown in
The pair of substrate holders 313 is insulated from each other and also insulated from the vacuum chamber 302 at least in the deposition chamber 301, and thus can have potentials independent from each other. In the load-lock chamber 320, the deposition chamber 301, and the load-lock chamber 330, the pair of the substrate holders 313 are disposed to be opposed to each other. Specifically, the surfaces of the respective substrate holders 313 with the substrates W mounted, among both surfaces of each substrate holder, are disposed opposed to each other.
The pair of substrate holders 313 arranged in this way and having the substrates W mounted thereon is carried into the load-lock chamber 320, and then the inside of the load-lock chamber 320 is exhausted to vacuum. The load-lock chamber 320 is previously heated by the heater installed in the load-lock chamber 320, as needed.
After completion of predetermined evacuation or heating, the isolation valve 42 between the load-lock chamber 320 and the deposition chamber 301 is opened, and then the pair of substrate holders 313 with the substrates W mounted thereon is carried into the deposition chamber 1, and then the isolation valve 42 is closed. Thereafter, the load-lock chamber 320 is exposed again to the atmospheric air, thereby preparing reception of a next object to be processed.
The deposition on the substrate W carried into the deposition chamber 301 will be performed as follows. A process gas (deposition source gas, reaction gas, and auxiliary gas) is supplied into a space between the substrate holders 313 in the evacuated deposition chamber 301, thereby keeping the inside of the deposition chamber 301 at a predetermined pressure. In this state, an AC power with a high frequency is supplied from the AC plasma generation power supply 10 to the pair of substrate holders 313. As a result, an AC voltage is applied between the substrate groups fixed to the substrate holders 313, thereby generating the glow discharge between the substrates belonging to the two groups, that is, the pair of the substrate holders 313, whereby the coating is formed on the substrates W.
At this time, the plasma is formed mainly in a space between the substrate holders 313, so that the formed coating is unevenly distributed at a part facing the space. Thus, the coating is hardly formed on the inner surface of the deposition chamber 301. After completion of the formation of the coating, the output from the plasma generation power supply 10 is stopped to thereby terminate the introduction of the process gas. In this way, the deposition process is completed.
Then, the isolation valve 43 between the load-lock chamber 330 and the deposition chamber 301 is opened, so that the substrates W are transported from the deposition chamber 301 into the load-lock chamber 330 together with the substrate holders 313. After completion of the transportation, the isolation valve 43 between both the chambers 301 and 330 is closed, so that the deposition chamber 301 is brought again into a standby state for carrying-in of the substrates W from the load-lock chamber 20.
After cooling the substrate W for a predetermined cooling time, the load-lock chamber 330 receives the atmospheric air or inert gas introduced thereinto to be at an atmospheric pressure. Then, the isolation valve 44 is opened, so that the substrates W are carried out of the load-lock chamber 330, together with the substrate holders 313. In this way, the deposition process is completed. After closing the isolation valve 44, the load-lock chamber 330 is exhausted again to be brought into the standby state for transfer of a next lot from the deposition chamber 301.
Accordingly, the plasma CVD apparatus 300 of the third embodiment forms the coating on the substrates and the substrate holders, but hardly forms the coating on the wall surface of the deposition chamber and the like. Since the substrates and the substrate holders are carried out every lot, the formation of the coating on the deposition chamber can be kept minimum. As a result, even though the deposition is performed on the numerous lots, the deposition chamber is not polluted, which can prevent the flying of flake of the coating that would otherwise cause defects, or variation of the process accompanied by the formation of the insulating coating.
Now, a plasma CVD apparatus 400 according to a fourth embodiment of the invention will be described with reference to
As shown in
The plasma CVD apparatus 400 has a fewer compartments as compared to the plasma CVD apparatus 300 of the third embodiment, and thus can suppress facility cost.
Now, a plasma CVD apparatus 500 according to a fifth embodiment of the invention will be described with reference to
In a modified example, as shown in
In this way, the substrates W stacked at intervals in the form of multilayer, or the substrate holder 513 with the substrates W set thereat are carried into the plasma CVD apparatus 500.
The deposition on the substrates W carried into the deposition chamber 501 will be performed as follows. A process gas (deposition source gas, reaction gas, and auxiliary gas) is supplied into a space between the substrates W in the evacuated deposition chamber 501, or between the substrate holders 513, thereby keeping the space at a predetermined pressure. In this state, an AC power with a high frequency is supplied from the AC plasma generation power supply 10 to the substrates W, or the substrate holders 513 arranged in the form of multilayer. As a result, the AC voltage is applied between the substrates W of the group A or group B (or the substrates W fixed to the substrate holders 513), so that the glow discharge is generated between the substrates W belonging to the two groups (or between the substrate holders 513 of the two groups), thereby forming the coatings on the substrates W. In this case, a plasma is generated between the substrates W stacked in the form of multilayer (or between the substrate holders 513). Thus, the coating can be formed on both surfaces of the substrate W, or on both surfaces of the substrate holder 513.
Now, a plasma CVD apparatus 600 according to a sixth embodiment of the invention will be described with reference to
The respective isolation valves are disposed between the transfer chamber 610 and the respective chambers around the transfer chamber. Specifically, an isolation valve 61 is openably and closably provided between the transfer chamber 610 and the load-lock chamber 20. An isolation valve 62 is openably and closably provided between the transfer chamber 610 and the deposition chamber 1. An isolation valve 63 is openably and closably provided between the transfer chamber 610 and the intermediate layer deposition chamber 40. An isolation valve 64 is openably and closably provided between the transfer chamber 610 and the load-lock chamber 30. These isolation valves can maintain the transfer chamber 610, the deposition chamber 1, and the intermediate layer deposition chamber 40 in the state of evacuation during operation of the plasma CVD apparatus 600.
As shown in
The same or similar one as the table trolley 50 described in the first embodiment is used as a transport mechanism for the revolution table 5. In an example shown in
The procedure of the deposition process for the substrate W in the plasma CVD apparatus 600 will be described below.
The deposition process by the plasma CVD apparatus 600 involves, after depositing the intermediate layer via the evacuation, another deposition by the plasma CVD, cooling, and taking out the substrate W to the atmosphere, which are performed in this order. The substrates W mounted on the revolution table 5 will be processed in the following way. In an initial state, the isolation valves 61 to 66 are closed, and the transfer chamber 610, the deposition chamber 1, and the intermediate layer deposition chamber 40 are in the vacuum state.
The isolation valve 65 is opened, and the revolution table 5 with the substrates W mounted thereon is carried into the load-lock chamber 20. Thereafter, the isolation valve 65 is closed and the inside of the load-lock chamber 20 is exhausted to vacuum.
After completion of the exhaust from the load-lock chamber 20, the isolation valves 61 and 62 are opened, and then the revolution table 5 with the substrates W mounted on is moved to the intermediate layer deposition chamber 40 via the transfer chamber 610. After completion of the movement, the isolation valve 61 is closed.
The load-lock chamber 20 is exposed to the atmosphere after closing the isolation valve 61, and then by opening the isolation valve 65, the load-lock chamber 20 is brought into a standby state for next substrates W to be carried thereinto. In the intermediate layer deposition chamber 40, a coating supply source (sputter source) 6 is operated to form an intermediate layer serving as an underlayer for the CVD layer, on the surface of each substrate W.
After completion of the deposition of the intermediate layer at the intermediate layer deposition chamber 40, the isolation valves 62 and 63 are opened, and then the revolution table 5 with the substrates W mounted on is moved to the deposition chamber 1 via the transfer chamber 610. The intermediate layer deposition chamber 40 is brought into the standby state for transfer of next substrates W from the load-lock chamber 20.
In the deposition chamber 1, after closing the isolation valve 63, the substrates W of the two groups mounted on the revolution table 5 are respectively connected to both electrodes of the plasma generation power supply 10, so that the deposition is performed while introducing the process gas.
After completion of the deposition of the CVD layer in the deposition chamber 1, the isolation valves 63 and 64 are opened, and then the revolution table 5 with the substrates W mounted thereon is moved to the load-lock chamber 30 via the transfer chamber 610. The deposition chamber 1 is brought into the standby state for transfer of next substrates W from the intermediate layer deposition chamber 40.
In the load-lock chamber 30, the substrates W of the two groups mounted on the revolution table 5 wait until they are cooled to an appropriate temperature after the isolation valve 64 is closed. After the substrates W are cooled to the appropriate temperature, the atmospheric air is introduced into the load-lock chamber 30, and the isolation valve 66 is opened, so that the revolution table 5 with the substrates W mounted thereon is carried out of the load-lock chamber 30.
As mentioned above, the plasma CVD apparatus 600 forms the CVD coating on the substrates W and the revolution table 5, but hardly forms the CVD coating on the wall surface and the like of the deposition chamber 1. Since the substrates W and the substrate holders are carried out to the outside of the plasma CVD apparatus 600 every lot, the formation of the coating on the deposition chamber 1 can be kept minimum. As a result, even though the deposition is performed on the numerous lots, the deposition chamber 1 is not polluted, which prevents the flying of flake of the coating that would otherwise cause defects, or variation of the process accompanied by the formation of the insulating coating. In particular, the plasma CVD apparatus 600 can perform a continuous deposition process while maintaining the deposition chamber 1 in the vacuum state, thereby effectively processing the numerous lots to suppress the pollution of the deposition chamber 1. This is a very effective means for stably operating the plasma CVD apparatus 600 for a long time.
Now, a plasma CVD apparatus 700 according to a seventh embodiment of the invention will be described with reference to
As shown in
The transfer chamber 610 is provided with the rotation transport mechanism 710, unlike the plasma CVD apparatus 600. The rotation transport mechanism 710 includes a rotatable central shaft 711, and four extensible arms 712 disposed around the shaft at intervals of 90°. The partition plate 720 is attached to the tip end of each arm 712. As shown in
As shown in
In the present embodiment, the two rotation tables 4 are arranged on the table 730, and each rotation table 4 has the substrate W mounted thereon. However, alternatively, the form of the table and the mounting state of the substrate W may be the same as those of other embodiments described above.
The procedure of the deposition process for the substrate W in the plasma CVD apparatus 700 will be described below. The deposition process in the plasma CVD apparatus 700 involves evacuation, heating, deposition of the intermediate layer, deposition by the plasma CVD, cooling, and taking out the substrate to the atmosphere, which are performed in this order in the same way as that in the plasma CVD apparatus 600. The substrates W mounted on the table 730 are processed as follows.
The atmospheric air is introduced into the load-lock chamber 30, while the load-lock chamber 30 is independently separated from other compartments by the partition plate 720. Thereafter, the isolation valve 65 is opened to expose the inside of the load-lock chamber 30 to the atmospheric air, so that the substrates W subjected to the deposition process are taken out of the table 730. Then, next substrates W mounted on the table 730 are carried into the load-lock chamber 30. Thereafter, the isolation valve 65 is closed and the inside of the load-lock chamber 30 is exhausted to vacuum.
After completion of the exhaust from the load-lock chamber 30, the central shaft 711 rotates by 90° in the anticlockwise direction with the arms 712 of the rotation transport mechanism 710 shrinking. After end of the rotation, the arms 712 of the rotation transport mechanism 710 are extended to transport the table 730 into the heating chamber 21. At this time, the partition plate 720 makes the heating chamber 21 independent from other compartments (with all four compartments made independent from each other). Thereafter, a heater 17 disposed in the heating chamber 21 heats the substrates W by increasing its temperature, while rotating the rotation table 4.
When the heating of the substrates W in the heating chamber 21 is completed, the central shaft 711 rotates by 90° in the anticlockwise direction with the arms 712 of the rotation transport mechanism 710 shrinking. After end of the rotation, the arms 712 of the rotation transport mechanism 710 are extended to transport the table 730 into the intermediate layer deposition chamber 40. At this time, the partition plate 720 makes the intermediate layer deposition chamber 40 independent from other compartments. Thereafter, the coating supply source (sputter source) 6 is operated while rotating the rotation table 4 to form the intermediate layer serving as an underlayer for the CVD layer, on the surface of each substrate W.
Once the deposition of the intermediate layer in the intermediate layer deposition chamber 40 is completed, the central shaft 711 rotates by 90° in the anticlockwise direction with the arms 712 of the rotation transport mechanism 710 shrinking. After end of the rotation, the arms 712 of the rotation transport mechanism 710 are extended to transport the table 730 into the deposition chamber 1. At this time, the partition plate 720 makes the deposition chamber 1 independent from other compartments. Thereafter, the substrates W belonging to the two groups are respectively connected to both electrodes of the plasma generation power supply 10, while the rotation tables 4 are rotating. In this way, the deposition is performed while introducing the process gas.
After completion of the deposition of the CVD layer in the deposition chamber 1, the central shaft 711 rotates by 90° in the anticlockwise direction with the arms 712 of the rotation transport mechanism 710 shrinking. After end of the rotation, the arms 712 of the rotation transport mechanism 710 are extended to transport the table 730 into the load-lock chamber 30. At this time, the partition plate 720 makes the load-lock chamber 30 independent from other compartments. Thereafter, the substrates W of the two groups wait until they are cooled to the appropriate temperature. After the substrates W are cooled to the appropriate temperature, the atmospheric air is introduced into the load-lock chamber 30, and the isolation valve 65 is opened, so that the substrates W are carried out of the load-lock chamber 30.
In this way, the deposition process (which involves evacuation, heating, deposition of the intermediate layer, deposition of the CVD layer by the plasma CVD, and cooling) is performed with the isolation valve 65 closed while all four compartments are in the vacuum state. When the arms 712 shrinks in this state, the four partition plates 720 are drawn into the center of the transfer chamber 610 with the substrate W mounted on the tables 730. In this state, the central shaft 711 can rotate by 90° in the anticlockwise direction. Thereafter, once the arms 712 are extended, the respective substrates W can be transported to the compartment to be subjected to next processing of the deposition process.
This kind of deposition process can also be simultaneously performed on the substrates W accommodated in the respective four compartments. In this way, the process efficiency can be drastically improved.
As mentioned above, the plasma CVD apparatus 700 hardly forms the CVD coating on the wall surface or the like of the deposition chamber 1, and thus can keep the formation of the coating on the deposition chamber 1 minimum, like the plasma CVD apparatus 600. As a result, even though the deposition is performed on the numerous lots, the deposition chamber 1 is not polluted or contaminated, which prevents the flying of flake of the coating that would otherwise cause defects, or variation of the process accompanied by the formation of the insulating coating. In this way, the pollution of the deposition chamber 1 can be suppressed, which is very effective for stably and effectively operating the plasma CVD apparatus 700 for a long time.
Note that the number of compartments disposed is changed depending on the number of process steps, and a rotation angle per one rotation by the rotation transport mechanism 710 is also changed.
The present invention is not limited to each embodiment described above, and various modifications and changes can be appropriately made to the shape, structure, and material of the respective components, and the combination thereof without changing the spirit of the invention. In the present embodiments disclosed, the features not definitely disclosed, for example, operating conditions, process requirements, various parameters, size, weight, and volume of components, and the like do not depart from the range that can be normally implemented by a person skilled in the art. Thus, those features can be easily made by a normal person skilled in the art.
Accordingly, the present invention can provide the in-line plasma CVD apparatus with a high production efficiency that is less likely to deposit a CVD coating on a part other than a substrate, thereby being capable of stably performing its operation without cleaning for a long time. The in-line plasma CVD apparatus includes the deposition chamber and a compartment other than the deposition chamber. The substrate is conveyed between the deposition chamber and the compartment. The deposition chamber includes a vacuum chamber, a pump for exhausting the air from the vacuum chamber, a gas supply unit for supplying a source gas into the vacuum chamber, and an AC plasma generation power supply for generating a plasma in the source gas supplied into the vacuum chamber. In the deposition chamber, the substrates are divided or classified into two groups. Specifically, the substrates belong to either a first group which is connected to one pole of the plasma generation power supply, or a second group which is connected to the other pole of the plasma generation power supply.
In the invention, preferably, the substrates of the two groups can be configured to be flat plate-shaped substrates opposed to each other.
Further preferably, the substrates of the two groups are flat plate-shaped substrates fixed onto holders alternately arranged at intervals. Alternatively, the substrates of the two groups are flat plate-shaped substrates alternately arranged at intervals, and the substrates of the two groups or the substrate holders can be configured to alternately belong to groups different from each other.
Further preferably, the substrates of the two groups can be configured to be mounted on the substrate holders that respectively rotate during the deposition process.
Further preferably, the substrates of the two groups can be configured to be mounted on the substrate holders that respectively rotate and revolve during the deposition process.
Further preferably, the substrates of the two groups are mounted on the substrate holders that rotate and revolve. The number of the rotation tables belonging to the first group is set to the same as that of the rotation tables belonging to the second group. The rotation tables of the first group and the rotation tables of the second group can be configured to be alternately arranged one by one around the revolution axis.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-282954 | Dec 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/007338 | 12/12/2013 | WO | 00 |
