JP2002356769A - Method and apparatus for plasma treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the highest temperature of a substrate. SOLUTION: Plasma treatment in a vacuum treatment chamber 1 is performed a plurality of times while cooling the substrate during rest time between the treatments. When continuously performing the treatments in a plurality of treatment chambers, the temperature of the substrate is increased by performing the treatments together except a treatment in the treatment chambers reaching the highest temperature, a radiation heat is increased thereby, and the treatment is performed a plurality of times in the treatment chamber reaching the highest temperature. In order to prevent a target 4 and a wall surface of the treatment chamber from hindering the radiation heat, a shielding plate 8 is provided between the substrate 7 and the target 4 or the wall surface of the treatment chamber 1 to increase the radiation heat from the substrate 7 during the waiting time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to sputtering,
The present invention relates to a plasma processing method and apparatus for performing processing using plasma such as CVD and dry etching.

[0002]

2. Description of the Related Art As a technique for processing a substrate by generating plasma in a processing chamber in a reduced pressure atmosphere, sputtering or CV
D and dry etching. Hereinafter, a sputtering apparatus will be described as an example of a plasma processing apparatus with reference to FIGS.

In FIG. 5, 11 is a vacuum processing chamber, 12 is an exhaust port, 13 is a gas inlet for introducing a sputtering gas, 14 is a target, 15 is a high voltage power supply, and 16 is a magnetron arranged on the back surface of the target 14. Magnet, 17
Is a substrate set in the vacuum processing chamber 11 so as to face the surface of the target 14.

When a substrate 17 is set in the vacuum processing chamber 11, a sputtering gas is introduced while evacuating the vacuum processing chamber 11, and power is supplied from a high-voltage power supply 15 to the target 14, a high-density plasma for sputtering is formed. Occurs. At this time, since the lines of magnetic force are generated by the magnetron magnet 16 so as to close on the surface of the target 14, a higher-density plasma is generated and a film can be formed at a high speed. When the ions in the plasma hit the surface of the target 14, atoms of the target 14 are sputtered,
The thin film is formed by adhering to the opposing surfaces of the substrate 17.

Normally, as shown in FIG. 6, film formation is performed by one discharge, and the time until the substrate 17 is carried out is a standby time.

[0006]

By the way, during the film formation time, plasma is generated in the vacuum processing chamber 11, and charged particles in the plasma flow into the substrate 17, and the temperature of the target 14 becomes high. Also, the temperature of the substrate 17 rises due to radiant heat from the wall surface of the vacuum processing chamber 11. For this reason, during the discharge period, the temperature of the substrate 17 rises at a stretch and may affect the film characteristics, which is not preferable. When a material having low heat resistance such as resin is used for the substrate 17, the substrate 17 itself may be deformed or melted.

As a means for solving such a problem, conventionally, the back surface of the substrate 17 or a substrate holder for fixing the substrate 17 is cooled to prevent the temperature of the substrate 17 from rising. There is a problem that cooling is not enough to reduce the temperature rise on the substrate surface.
In particular, when the substrate 17 is made of a material having poor thermal conductivity such as a resin, a temperature gradient is formed between the front surface and the rear surface of the substrate 17, which may cause a problem such as distortion. Further, when the film is formed by bringing the substrate holder into contact with the substrate 17 in order to increase the cooling efficiency, there is a possibility that the substrate 17 may be damaged by foreign substances or the like attached to the substrate holder.

As described above, the temperature of the substrate 17 rises due to the flow of the charged particles into the substrate 17 and the radiant heat from the target 14 and the wall surface of the vacuum processing chamber 11, and the substrate 17 is deformed or dissolved, and the quality of the film is reduced. There was a problem that it could cause deterioration.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a plasma processing method and apparatus capable of reducing the maximum temperature of a substrate.

[0010]

According to the plasma processing method of the present invention, the processing time in one processing chamber is divided into a plurality of processing times.
A waiting time is provided between each processing, and the processing is performed while radiating heat during the waiting time, so that the maximum temperature of the substrate can be kept low.

If the waiting time between each processing is set unequally, and the time of each processing is set unequal, the processing time is set appropriately according to the maximum temperature of the substrate, and the processing time is set. By setting the standby time in accordance with the rise in the temperature of the substrate, the ultimate temperature of the substrate can be kept lower.

Further, of the processing times, the n-th time is defined as t _n and the (n + 1) -th time is defined as t _{(n + 1)} .
t _n > t _{(n + 1)} , and among the standby times between the processes, the n-th time is T _n , the (n + 1) -th time is T _{(n + 1)} , and By setting _n > T _{(n + 1)} , the substrate temperature can be kept almost constant at a temperature close to the maximum attained temperature, the total amount of radiant heat can be increased, and the maximum attainable temperature of the substrate can be suppressed lower.

Further, of the processing times, the n-th time
To t_nAnd the m-th time is t_mAnd wait between each process
T is the nth time in the machine time_nAnd m-th time
To T _mAs t_n> T_mAll of n and m satisfying the relationship
T for all combinations _n> T_mSatisfy the relationship
And the substrate temperature is almost equal to the maximum temperature.
And maintain the maximum temperature of the substrate by increasing the total amount of radiant heat.
The degree can be kept lower.

Further, among the power input in each process, the n-th power is set to P _n , the (n + 1) -th time is set to P _{(n + 1)} , and P _n > P _{(n + 1)} is set. By doing so, the substrate temperature can be kept almost constant at a temperature close to the maximum attainable temperature, and the total amount of radiant heat can be increased to lower the maximum attainable temperature of the substrate.

Further, in a plasma processing method in which plasma processing is performed in a plurality of processing chambers and plasma processing is continuously performed in each processing chamber, the plasma processing method may be such that the substrate temperature becomes higher than the maximum allowable temperature if the continuous processing is performed once. Regarding the plasma processing, when the above-described plasma processing method is used, the substrate temperature can be kept almost constant at a temperature close to the maximum attainable temperature equal to or lower than the maximum allowable temperature, and the maximum amount of radiant heat is increased to lower the maximum attainable temperature of the substrate. Can be suppressed.

Further, in a plasma processing method in which plasma processing is performed in a plurality of processing chambers and plasma processing is continuously performed in each processing chamber, the plasma processing method may be such that the substrate temperature becomes equal to or higher than the maximum allowable temperature if continuous processing is performed at once. For the plasma processing, the above-described plasma processing method is used, and for the plasma processing in the other processing chambers, the processing time in each processing chamber is not divided into a plurality of times, so that the substrate temperature is close to the maximum attainable temperature equal to or lower than the maximum allowable temperature. The temperature can be kept almost constant, and the total amount of radiant heat can be increased to lower the maximum temperature of the substrate.

In a plasma processing method in which plasma processing is performed in a plurality of processing chambers and plasma processing is performed continuously in each processing chamber, when the same processing is performed in a plurality of continuous processing chambers, a plurality of processing Among the chambers, when the total processing time in at least any one of the subsequent processing chambers is shorter than the total processing time in the preceding processing chamber, the substrate temperature can be kept almost constant at a temperature close to the highest reached temperature, By increasing the total amount of radiant heat, the maximum temperature of the substrate can be kept lower.

Further, the plasma processing apparatus of the present invention is a plasma processing apparatus for processing a substrate by generating plasma in a processing chamber. A shielding plate is provided, and the shielding plate is made of at least one of Al, Ni, and Zn. By inserting the shielding plate between the target and the processing chamber wall surface and the substrate during the standby time, Since the amount of heat radiation from the substrate can be increased, the maximum temperature of the substrate can be suppressed lower.

When at least one of the surfaces of the shielding plate opposite to the surface facing the substrate is polished or mirrored, the temperature rise of the shielding plate is suppressed and the amount of heat radiation from the substrate is increased. Thus, the maximum temperature of the substrate can be kept lower.

Further, in a plasma processing apparatus for processing a substrate by generating plasma in a processing chamber, a shielding plate which can be inserted between a target or a processing chamber wall surface and the substrate which is heated by the plasma processing is provided. If at least one of the surfaces opposite to the surface facing the substrate is a polished surface or a mirror surface, the amount of heat released from the substrate can be increased, so that the maximum temperature of the substrate can be suppressed lower. it can.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the plasma processing method and apparatus of the present invention will be described below with reference to FIGS.

In FIG. 1, 1 is a vacuum processing chamber, 2 is an exhaust port, 3 is a gas inlet for introducing a sputtering gas, 4
Is a target, 5 is a high-frequency or DC power supply for supplying high-voltage power to the back surface of the target 4, 6 is a magnetron magnet arranged on the back surface of the target 4, 7 is inside the vacuum processing chamber 1 so as to face the surface of the target 4. Is a shielding plate which can be interposed between the substrate 7 and the target 4 or the wall surface of the vacuum processing chamber 1 exposed to plasma. The shield plate 8 may be taken in and out by a method using a rotation mechanism as indicated by an arrow in the figure, or by a straight forward / backward movement, and the driving means may be an air actuator or a motor.

In the above configuration, a plasma is generated in the vacuum processing chamber 1 by introducing a sputtering gas while evacuating the vacuum processing chamber 1 and applying a voltage to the target 4 by the power supply 5. At this time, Ar or Xe is generally used as a sputtering gas. Ions present in the plasma are attracted to the target 4 to cause a sputtering phenomenon, and sputter particles repelled from the target 4 adhere to the substrate 7 to form a thin film. However, at the same time, the temperature of the substrate 7 rises because charged particles flow into the substrate 7 from the plasma. Rather than performing film formation in one vacuum processing chamber 1 at a time, as shown in FIG. 2, the maximum temperature of the substrate 7 divided into a plurality of times can be suppressed.

More specifically, in the case where the substrate 7 is introduced into the vacuum processing chamber 1 and the substrate 7 is removed after performing the process using plasma, the processing time is generally shorter than the tact time. 6, a waiting time can be taken before and after the processing is performed, as shown in FIG. Therefore, as shown in FIG. 2, the film formation in the vacuum processing chamber 1 can be divided into a plurality of times, and a standby time during which no plasma is generated between the film formations can be taken.

If there is no room for the tact time,
For example, the standby time can be ensured by increasing the power supplied to the target 4 to increase the film forming speed.

The substrate temperature rises during film formation, but decreases during the standby time because heat is released by radiant heat. In order to form a film having the same thickness, the amount of heat flowing into the substrate 7 is substantially the same regardless of whether the film is formed once or in a plurality of times. Therefore, in order to keep the maximum temperature attained by the substrate 7 low, it is more advantageous to divide the film into a plurality of times as shown in FIG. Can be kept low.

The amount of heat radiation from the substrate 7 is proportional to the fourth power of the substrate temperature in accordance with the Stefan-Boltzmann law.
It is better to keep the temperature of the substrate 7 high. In other words, when the film formation is divided into a plurality of times, the initial film formation time is increased to raise the temperature of the substrate 7 to near the maximum temperature, and then the standby time is increased to release the substrate 7 by radiation of heat. Cool and
By sequentially shortening the film formation time and the standby time,
The substrate temperature can be kept almost constant at a temperature close to the maximum attained temperature, and the total amount of radiant heat can be increased to keep the maximum attained temperature of the substrate 7 low. Further, since the change in the substrate temperature can be suppressed to a small value, adverse effects such as thermal distortion of the substrate 7 can also be reduced.

Further, in this embodiment, a shielding plate 8 is provided between the substrate 7 and the target 4 or the high-temperature portion of the wall surface of the vacuum processing chamber 1, and is moved to a position that does not hinder sputtered particles during film formation. Since it is inserted between the target 4 and the substrate 7 only during the standby time after the film formation, the amount of heat radiation from the substrate 7 during the standby time can be increased. That is,
When there is a high-temperature object around the substrate 7, effective heat radiation from the substrate 7 is hindered. In the case of a sputtering apparatus, the target 4 or the wall surface of the vacuum processing chamber 1 at a position facing the substrate 7 causes Although it will hinder heat radiation, the shielding plate 8
Is provided, heat radiation by heat radiation is effectively performed, and the maximum temperature of the substrate 7 can be reduced.

Further, if a material having a low heat radiation rate is used as the material of the shielding plate 8, the temperature of the shielding plate 8 itself does not have to hinder the heat radiation of the substrate 7. Specifically, Al, Ni,
Even if Zn or the like is oxidized, the emissivity may be low. Alternatively, a material such as iron or stainless steel is used as a base material, and Ni, Z
A plating layer such as n may be formed. The emissivity also changes depending on the state of the surface. In order to keep the emissivity low, the surface may be smoothed, and may be polished or mirror-finished.

The film formation in one vacuum processing chamber in the phase change rewritable optical disk sputtering apparatus will be described below. Using a target 4 having a diameter of 203 mm,
A film is formed on a 20 mm polycarbonate substrate. ZnS · SiO ₂ which is used as a protective film performs the film formation by RF sputtering, to deposit a film thickness of 50~200nm at 5～20S, the substrate temperature is very hot.

FIG. 3 shows a result of simulating a change in the substrate temperature in order to show the effect of reducing the increase in the substrate temperature according to the present invention. The calculation conditions are as follows: thickness 0.6 mm, diameter 12
For a 0 mm polycarbonate substrate, ZnS
An iO ₂ target is arranged at a distance of 58 mm, a high-frequency power of 3.4 kW is applied for a total of 10 s, and the
Was formed when a ZnS.SiO ₂ film was formed. The amount of heat flowing into the substrate was 430 from the comparison with the measured value of the substrate temperature.
0W And The specific gravity of polycarbonate is 1.
2. The specific heat is 1.26 J / kg and the emissivity is 0.9.
Radiation was calculated as obeying Stefan-Boltzmann's law. Assuming a tact time of 20 s, comparison was made from two viewpoints: the substrate temperature 20 s after the start of film formation and the maximum temperature reached by the substrate.

As shown in FIG. 3, in the case of the film formation pattern A in which the film formation is performed once, the maximum temperature of the substrate is 72.4.
° C and the highest. However, the amount of heat radiation from the substrate increases because the substrate temperature increases, and as a result, the substrate temperature after 20 s is the lowest at 64.7 ° C. On the other hand, in the case of the film formation pattern B in which the film formation is divided into two, the maximum temperature of the substrate can be kept as low as 69.4 ° C., but the temperature after 20 s is higher than 65.7 ° C. Further, in order to further reduce the maximum temperature reached by the substrate, a film forming pattern C in which the first film forming time and the subsequent cooling time are long, and the next film forming time and the cooling time are short is effective. The highest temperature reached is 66.9 ° C.

Next, a case where a laminated film is continuously formed in a plurality of film forming chambers will be described. In this case, the film formation chamber where the substrate reaches the maximum temperature is determined by the material and film thickness of each layer, so that the film formation in the film formation chamber where the maximum temperature is reached is divided into a plurality of times and the maximum temperature of the substrate is suppressed low. It is better to raise the substrate temperature in order to increase the amount of heat radiation from the substrate except in the film forming chamber where the temperature reaches the maximum temperature. By increasing the temperature, the radiation can be increased, the heat radiation amount can be increased, and the maximum temperature of the substrate can be kept low.

As a specific example of forming this laminated film, a description will be given of the case of forming a phase change rewritable optical disk. A phase-change rewritable optical disk is composed of a laminated layer of films such as a reflective layer and a protective layer, in addition to a recording layer that causes a phase change. Among them, the substrate temperature reaches a maximum temperature in a film forming chamber for forming a protective layer of ZnS.SiO ₂ by high frequency sputtering.
Table 1 shows an example in which the ultimate temperature of the substrate is reduced by dividing the deposition time of ZnS.SiO ₂ .

[0035]

[Table 1] In Table 1, when a laminated film is formed with a tact time of 24 s, the film forming time is 9.7 s when ZnS.SiO _{2 is formed} with a high frequency power of 5 kW. In this case, if the maximum temperature of the substrate was 92.6 ° C. when the film formation was performed once, the total of 9.7 s was divided into two times, and at that time, divided into 4.85 s. By dividing into film-7.15s pause-4.85s film formation-7.15 pause, the temperature can be reduced to 87.4 ° C, and firstly, the film formation time and the pause time are unequally divided so as to be longer. 83.7 ° C. when divided into 7.2 s film formation—11.3 s pause—2.5 s film formation—3.0 pause
Can be reduced.

Next, another embodiment of the plasma processing method and apparatus of the present invention will be described with reference to FIG.

In the above embodiment, the processing is performed in a single vacuum processing chamber 1, but in this embodiment, the processing is performed continuously in a plurality of vacuum processing chambers 1 (1a to 1e). Have been. In FIG. 4, a substrate 7 is provided on one side of a polygonal transfer chamber 9 in which transfer means 9a for sequentially transferring substrates is provided.
And a vacuum processing chamber 1 (1a to 1e) having the configuration described in the above embodiment are disposed on the other sides.

In this vacuum processing apparatus, the substrate 7 is sequentially fed into each of the vacuum processing chambers 1 (1a to 1e), and the same or different processing is successively performed. At that time, for the plasma processing in the vacuum processing chamber where the substrate temperature becomes equal to or higher than the maximum allowable temperature when the continuous processing is performed at once, the cooling time is set by dividing the processing time into a plurality of times as in the above embodiment, and other processing is performed. In the plasma processing in the chambers, the temperature of the substrate 7 being processed in each of the vacuum processing chambers 1a to 1e is substantially equal to or lower than the maximum allowable temperature by not dividing the processing time in each processing chamber into a plurality. It can be kept constant, so that the total amount of radiant heat can be increased, and as a result, the maximum temperature of the substrate 7 can be kept lower.

The plurality of processing chambers 1 (1a to 1e)
When the same processing is performed in the subsequent processing chambers, the temperature of the substrate 7 has already risen in the preceding processing, so that the total processing time in at least one of the following processing chambers among the plurality of processing chambers Is shorter than the total processing time in the preceding processing chamber, the temperature of the substrate 7 can be kept almost constant at a temperature close to the maximum attained temperature, and the total amount of radiant heat is increased to increase the maximum attainable temperature of the substrate 7. It can be kept lower.

[0040]

According to the plasma processing method and apparatus of the present invention, the plasma processing for the substrate is performed in a plurality of times as described above, and the processing is performed while cooling the substrate during the downtime during the processing. The maximum temperature of the substrate can be kept low.

Further, when processing is continuously performed in a plurality of processing chambers, in a processing chamber where the substrate temperature becomes higher than the maximum allowable temperature if the continuous processing is performed at once, the maximum temperature of the substrate can be lowered by dividing the processing into a plurality of times. In the other processing chambers, the maximum temperature of the substrate can be suppressed by performing the processing at once and raising the substrate temperature to increase the radiant heat.

Further, a shield plate is provided between the substrate and the target or the wall of the processing chamber to prevent the target or the wall of the processing chamber from obstructing the heat radiation from the substrate, so that the amount of heat radiated from the substrate during the standby time is reduced. And the maximum temperature of the substrate can be kept low.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment in which a plasma processing apparatus of the present invention is applied to a sputtering apparatus.

FIG. 2 is an explanatory diagram of an example of a film forming process in the embodiment.

FIG. 3 is an explanatory diagram showing a reduction effect of a maximum temperature of a substrate by various film forming steps in the embodiment.

FIG. 4 is a plan view showing a schematic configuration of another embodiment of the plasma processing apparatus of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional sputtering apparatus.

FIG. 6 is an explanatory diagram of a film forming process in the conventional example.

[Explanation of symbols]

 1 vacuum processing chamber 4 target 7 substrate 8 shielding plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G075 AA22 BC02 BC04 BC06 CA47 EB31 EB37 FB02 4K029 BA46 BA51 BB02 BD12 CA05 DA00 EA06 EA09 5D112 FA04 FA09 FA10 GA20 GA22 5D121 AA04 EE03 EE20 EE30

Claims (13)

[Claims] 1. A plasma processing method, wherein a processing time in one processing chamber is divided into a plurality of times, and a standby time is provided between each processing. 2. The plasma processing method according to claim 1, wherein the time of each processing is set unequally. 3. The plasma processing method according to claim 1, wherein a standby time between each processing is set unequally. 4. An n-th time of each processing time is represented by t
_n , and the (n + 1) th time is t _{(n + 1)} , and t _n
3. The plasma processing method according to claim 2, wherein the value is set to> t _{(n + 1)} . 5. The standby time between the processes is set such that the n-th time is T _n , the (n + 1) -th time is T _{(n + 1)} , and T _n > T _{(n + 1)} The plasma processing method according to claim 3, wherein the plasma processing is performed. 6. An n-th time of each processing time is represented by t
_n , the m-th time is t _m, and the n-th time is T _n , and the m-th time is T
As _m, t _n> for all combinations of n and m that satisfy a relation of t _m, plasma processing method according to claim 2 or 3, wherein the satisfying the relation T _n> T _m. 7. The power input in each process,
Let the n-th power be P _n and the (n + 1) -th time be P n
_2. The plasma processing method according to claim _{1, wherein (n + 1)} is set to satisfy _Pn > P _{(n + 1)} . 8. A plasma processing method in which plasma processing is performed in a plurality of processing chambers and plasma processing is continuously performed in each of the processing chambers. A plasma processing method using the plasma processing method according to any one of claims 1 to 7 for the plasma processing. 9. A plasma processing method in which plasma processing is performed in a plurality of processing chambers and plasma processing is continuously performed in each of the processing chambers. The plasma processing, wherein the plasma processing method according to any one of claims 1 to 7 is used, and the plasma processing in the other processing chamber does not divide the processing time in each processing chamber into a plurality of pieces. Processing method. 10. A plasma processing method in which plasma processing is performed in a plurality of processing chambers and the plasma processing is performed continuously in each of the processing chambers. Of the chambers, the total processing time in at least one of the subsequent processing chambers,
A plasma processing method, wherein the total processing time is shorter than a total processing time in a preceding processing chamber. 11. A plasma processing apparatus for processing a substrate by generating plasma in a processing chamber, wherein a shielding plate that can be inserted between a target or a processing chamber wall surface and the substrate that is heated by the plasma processing is provided. Are Al, Ni,
A plasma processing apparatus comprising at least one material of Zn. 12. The plasma processing apparatus according to claim 11, wherein at least one of the surfaces of the shielding plate opposite to the surface facing the substrate is polished or mirrored. 13. A plasma processing apparatus for processing a substrate by generating plasma in a processing chamber, wherein a shielding plate which can be inserted between a target or a processing chamber wall surface and the substrate, which is heated by the plasma processing, is provided. A plasma processing apparatus characterized in that at least one of the surfaces opposite to the surface facing the substrate has a polished surface or a mirror surface.