JP2001085417A - Device and method for plasma treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma treatment device which can uniformly improve step coverage and film thickness. SOLUTION: A plasma treatment device is provided with a plasma-generating chamber 14, which is sandwiched between an upper electrode 30 and a lower electrode 32 connected to a high-frequency power source, and in which radicals are generated by generating a plasma, and a treatment chamber 16 which is provided on the downstream side of the plasma-generating chamber 14 and constituted to be evacuated for performing prescribed plasma treatment on an object W to be treated with the flow-down radicals. The plasma-generating chamber 14 is divided concentrically into a plurality of parts and the concentration of the radical is adjusted, in such a way that the concentration becomes higher going toward the peripheral section from the central part of the chamber 14. Consequently, for example, step coverage and film thickness uniformity can be improved.

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 and a plasma processing method for performing processing such as film formation on a target object such as a semiconductor wafer using plasma.

[0002]

2. Description of the Related Art Generally, in order to perform various processes such as film formation and etching on a semiconductor wafer, processing can be performed in a relatively low temperature range as compared with thermal CVD or the like. They tend to be heavily used. Here, a case where an insulating film such as a SiO ₂ film is formed using plasma will be described as an example. FIG. 12 is a schematic configuration diagram of a conventional parallel plate type plasma processing apparatus. In the illustrated example, a mounting table 4 also serving as a lower electrode is provided at the bottom of the processing container 2 which can be evacuated, and a semiconductor wafer W to be processed is mounted on the mounting table 4. A shower head 6 serving also as an upper electrode is provided on the ceiling of the processing vessel 2 via an insulator 8. For example, silane, oxygen, Ar gas, or the like is used as a processing gas. It can be supplied inside. Further, a high frequency power supply 10 of, for example, 13.56 MHz is connected to the shower head unit 6 to generate plasma between the shower head unit 6 as the upper electrode and the mounting table 4 as the lower electrode, Thus, radicals (active species) are generated to deposit, for example, a SiO ₂ film on the wafer W.

[0003]

However, in this type of parallel plate type plasma processing apparatus, the process pressure is relatively high, for example, about 0.1 to 1.0 Torr, and therefore, the radicals as film forming particles Will fly isotropically over the wafer due to intermolecular collisions. As a result, when burying contact holes or wiring trenches with a large aspect ratio, voids will occur due to poor step coverage, for example. there were. Here, the concentration of the processing gas supplied into the processing chamber 2 is generally high in the central portion of the wafer W and lower in the peripheral portion, so that the film thickness deposited on the wafer W The thickness tends to increase at the center of the wafer W and decrease toward the periphery, and there is a problem that the in-plane uniformity of the film thickness is deteriorated. The present invention has been devised in view of the above problems and effectively solving them. An object of the present invention is to provide a plasma processing apparatus and a plasma processing method that can improve, for example, step coverage and uniformity of film thickness.

[0004]

The invention defined in claim 1 is a plasma generation chamber for generating radicals inside by being sandwiched between an upper electrode and a lower electrode connected to a high-frequency power supply; A plasma processing apparatus having a processing chamber provided below the plasma generation chamber and capable of performing vacuum processing for performing a predetermined plasma processing on an object to be processed by radicals flowing down, wherein the plasma generation chamber is concentric. The processing chamber is configured so that the concentration of the radical is set higher in the peripheral part than in the central part of the processing chamber.

First, by generating plasma in a plasma generation chamber having an upper electrode and a lower electrode, the gas is activated in the processing to form radicals, and the radicals flow downward to flow into the processing chamber to be processed. A predetermined plasma process, for example, a film forming process is performed on the body. At this time, the plasma generation chamber is divided into a plurality of concentric sections, and the concentration of radicals in the peripheral portion of the processing chamber is set to be higher than that in the central portion. Thus, for example, a deposited film tends to be thickly deposited on the peripheral portion of the object to be processed. For this reason, it is possible to improve the uniformity of the processing of the whole object to be processed, that is, the in-plane uniformity of the film thickness in the case of film formation.

[0006] As defined in claim 2, for example, a plurality of radical flow holes for passing the radicals are formed in the lower electrode. For example, if a plurality of vacuum exhaust ports for evacuating the processing chamber are formed on a side wall that partitions the processing chamber, the atmosphere in the processing chamber is horizontal. Since the evacuation is performed in the direction as it is, the exhaust conductance is increased accordingly, and the process pressure can be further reduced to increase the anisotropy in the direction in which the radicals fly, thereby increasing the step coverage. As defined in claim 4, for example, a processing gas is individually supplied to each of the plurality of divided plasma generation chambers.

According to a fifth aspect of the present invention, for example, a distance between the lower electrode and a mounting table on which the object is placed is a length within a range from a radius to a diameter of the object. Is set to According to this, the function of the directional distribution of the radicals incident on the object to be processed is distributed more in the vertical direction, that is, since the anisotropy in the flying direction of the radicals is increased, the step coverage is further improved. It is possible to do. As set forth in claim 6, for example, the pressure in the processing chamber is set so that the mean free path of the radical falls within a range of about 1 to 2 times the distance between the lower electrode and the mounting table. Is done. As a result, since many generated radicals fly to the object without frequently causing intermolecular collisions, the anisotropy in the incident direction of the radicals is maintained at a high level, thus improving the step coverage. It is possible to do.

As defined in claim 7, for example, the upper limit electrode of the plurality of divided plasma generation chambers is divided into a plurality corresponding to the plasma generation chambers, and a high frequency voltage applied thereto is applied to a central portion. The room located in the peripheral part is set to be larger than that in the room. As a result, the plasma density of the plasma generation chamber located at the peripheral portion is increased, so that radicals having a higher concentration than the central portion can flow down from the plasma generation chamber into the processing chamber. Properties, for example, the in-plane uniformity of the film thickness can be improved. As defined in claim 8, for example, the opening area per unit area of the radical flow hole formed in the lower electrode may be set to be larger at a peripheral part than at a central part. According to this, the amount of radicals flowing down from the plasma generation chamber located in the peripheral portion is larger than that in the central portion, so that the in-plane uniformity of the processing, for example, the in-plane uniformity of the film thickness can be improved. It becomes possible. For example, a grid electrode may be arranged in the processing chamber. According to this, for example, if a DC fixed bias is applied to the grid electrode, charged particles such as electrons and ions are minimized from being incident on the object side so that only radicals are incident, Charge-up damage (Char
get up Damage) can be suppressed.

According to a tenth aspect of the present invention, there is provided a plasma processing apparatus for performing a predetermined plasma processing on an object to be processed, comprising: a cylindrical processing chamber accommodating the object to be processed and capable of being evacuated; A ring-shaped plasma generation chamber that is formed concentrically outside the processing chamber and is sandwiched between an upper electrode and a lower electrode connected to a high-frequency power source to generate plasma inside and generate radicals And a partition plate formed between the processing chamber and the plasma generation chamber and having a plurality of radical circulation holes. According to this, when plasma is generated in the plasma generation chamber having the upper electrode and the lower electrode, a radical of the processing gas is generated by this, and the radical is located inside through the radical circulation hole of the partition plate. After flowing into the processing chamber, the object to be processed is subjected to a predetermined plasma process, for example, a plasma film forming process. In this case, since the radicals act so as to flow toward the central portion rather than the peripheral portion of the object to be processed, the in-plane uniformity of the processing can be improved as compared with the conventional apparatus which flows from the central portion toward the peripheral portion. For example, in-plane uniformity of the film thickness can be improved. In addition, since the plasma generation chamber and the processing chamber are clearly separated from each other, even if the plasma itself has, for example, non-uniformity in concentration, it is possible to prevent the non-uniformity from directly affecting the processing of the object to be processed. It becomes possible.

As defined in claim 11, for example, the ring-shaped plasma generation chamber may be provided with a plurality of gas inlets at predetermined intervals along the outer periphery thereof. According to this, it becomes possible to uniformly introduce a processing gas or the like into the plasma generation chamber. As defined in claim 12, for example, a grid electrode may be provided on at least the inner peripheral side of the inner peripheral side and the outer peripheral side of the ring-shaped plasma generation chamber. According to this, the charged particles can be prevented from flowing out of the plasma generation chamber, the efficiency of plasma generation can be increased, and the object to be processed can be suppressed from being charged up. . As defined in claim 13, for example, a vacuum exhaust port for evacuating the inside may be formed.

For example, the object to be processed in the processing chamber is supported at a position lower than a bottom level of the plasma generation chamber, and the object is supported on a side wall of the processing chamber. A vacuum exhaust port for evacuating the inside may be formed. As defined in claim 15, for example, a ring-shaped baffle plate may be provided downward at a peripheral portion of a ceiling portion of the processing chamber. According to this, the discharge of radicals is blocked by the baffle plate, and the concentration of radicals in the processing chamber rises.
Processing efficiency can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a plasma processing apparatus and a plasma processing method according to the present invention will be described below with reference to the accompanying drawings. 1 is a configuration diagram showing a plasma processing apparatus of the first invention, FIG. 2 is a view showing a state when a mounting table is lowered in the plasma processing apparatus shown in FIG. 1, and FIG. 3 is a plane showing an arrangement state of exhaust ports. FIG. 4 is a diagram showing the supply state of the processing gas and the application state of the high frequency power supply, and FIG. 5 is a plan view showing the lower electrode. Here, a case where a plasma film forming process is performed as the plasma process will be described as an example. As shown in the figure, the plasma processing apparatus 10 has a processing container 12 made of aluminum and formed into a substantially cylindrical shape as a whole. The inside of the processing container 12 is divided into three areas in the vertical direction. The upper area is a plasma generation chamber 14, the middle area is a processing chamber 16, and the lower area is a loading / unloading chamber 18. In the loading / unloading room 18,
A mounting table 20 for mounting a semiconductor wafer W, which is an object to be processed, on the upper surface thereof is provided supported by a support 22.
The support column 22 and the mounting table 20 can be moved up and down by lifting means (not shown). The mounting table 20 is provided with an electrostatic chuck (not shown) and lifter pins used when loading / unloading the wafer. Further, a heater for heating the wafer W or a cooling unit for cooling the wafer may be provided as necessary.

An elastic bellows 24 is interposed between the periphery of the bottom opening of the processing container 12 and the peripheral edge of the lower surface of the mounting table 20 so as to improve the airtightness of the processing container 12. As described above, the mounting table 20 can be moved up and down while being maintained. A gate valve 26 for loading / unloading the wafer W is provided on the side wall of the processing container which partitions the loading / unloading chamber 18, and the loading / unloading of the wafer W is performed by moving the mounting table 20 downward as shown in FIG. It is designed to be performed in a state of being lowered. In addition, as shown in FIG. 3, a vacuum exhaust port 28 having a conical cross section, for example, is formed on the side wall of the processing chamber which defines the processing chamber 16 and has a diameter gradually reduced toward the outside in the radial direction. ing. A plurality of vacuum evacuation ports 28 are provided along the circumferential direction of the container, and four are provided at equal intervals in the illustrated example, and the atmosphere in the processing chamber 16 is radially outwardly, that is, substantially uniformly radially in the horizontal direction. It can be evacuated. By performing the horizontal pulling in this manner, the exhaust conductance can be set as large as possible. Exhaust paths extending from the respective vacuum exhaust ports 28 are combined into, for example, a single line, and are evacuated by a vacuum pump or the like (not shown). The vacuum exhaust port 28
The number is preferably two or more so that the internal atmosphere can be evenly reduced from the peripheral portion of the wafer.

On the other hand, the upper plasma generation chamber 14 is concentrically partitioned into a plurality, in the illustrated example, two. Specifically, the ceiling of the plasma generation chamber 14 is configured as an upper electrode 30 made of, for example, copper or aluminum, and the bottom is made of, for example, copper or aluminum in which a plurality of radical flow holes 34 of the same size are formed on the entire surface. It is configured as a lower electrode 32 (see FIG. 5). The upper electrode 30 is divided into a central upper electrode 30A at a central portion and a ring-shaped peripheral upper electrode 30B around the central upper electrode 30A.
Are electrically insulated. The upper electrode 30 itself is also attached to the upper end of the processing container 12 via an insulator 38. Further, the lower electrode 32 is also provided in the processing container 1.
The second side wall is attached via an insulator 40 and is electrically insulated. Then, the insulator 36 and the lower electrode 3 at the division of the center and peripheral upper electrodes 30A and 30B are formed.
By providing the partition wall 42 made of a ring-shaped insulator between the two, the plasma generation chamber 14 is separated into the cylindrical plasma generation chamber 14A and the ring-shaped peripheral plasma generation chamber 14B as described above. I have. A high-frequency power supply for plasma generation, that is, a high-frequency power supply for center 44A and a high-frequency power supply for periphery 44B are connected between the center and peripheral upper electrodes 30A and 30B and the lower electrode 32, respectively. Both of these high-frequency frequencies are, for example, 13.56 MHz. Here, the supply power per unit area of the electrode from the peripheral high-frequency power supply 44B is set to be larger than that for the center, and the plasma in the peripheral plasma generation chamber 14B is set. The concentration and the radical concentration are set to be higher than those of the central plasma generation chamber 14B.

As shown in FIG. 4, a center gas supply head 46A is provided at the center of the center upper electrode 30A.
The peripheral upper electrode 30B is provided with a plurality of peripheral gas supply heads 46B arranged at equal intervals along the circumferential direction thereof, in the illustrated example, four peripheral gas supply heads 46B. The processing gas is supplied evenly to the processing gas. The number of the peripheral gas supply heads 48B is not limited to the number as long as the gas can be supplied uniformly, and the whole may be connected in a ring shape. The gas supply paths 48A and 48B of the heads 46A and 46B respectively have flow controllers 50 such as mass flow controllers.
A and 50B are provided so that the flow rate of the supplied processing gas can be individually controlled. Here, for example, Ar gas is used as the plasma gas, and silane and oxygen are used as the film formation gas, but the gas type is not limited to this. Returning to FIG. 1, immediately below the lower electrode 32, a grid-like grid electrode 52 is attached by supporting the periphery of the grid electrode 52 inside the container via an insulator 53. A DC power supply 54 is connected to the grid electrode 52 to prevent electrons, load particles, and the like from flowing through the grid electrode 52 and flowing downward.

Next, the operation of the embodiment constructed as described above will be described. First, with the mounting table 20 lowered as shown in FIG. 2, an unprocessed semiconductor wafer W is loaded into the processing chamber 12, which has been preliminarily evacuated, via the gate valve 26. 20. Then, the gate valve 26 is closed and the mounting table 2 is closed.
0, the wafer W is moved into the processing chamber 1 as shown in FIG.
6 Then, silane, oxygen, and Ar gas whose flow rates are individually controlled are respectively supplied to the central gas supply head 46.
A and the peripheral gas supply heads 46B supply the gas into the central plasma generation chamber 14A and into the peripheral plasma generation chamber 14B, respectively. Here, a high-frequency voltage is applied between the upper electrode 30 and the lower electrode 32 from the high-frequency power sources 44A and 44B, and plasma is generated inside by Ar gas, and the processing gas is activated by the plasma. To generate radicals. These radicals flow down into the processing chamber 16 through the radical flow holes 34 of the lower electrode 32, react on the surface of the wafer W, and here react with SiO _2.
The film will be deposited on the wafer. During this time, the four vacuum exhaust ports 28 are evacuated, and the processing chamber 12 is maintained at a predetermined process pressure.

In this embodiment, the power applied to the peripheral upper electrode 30B per unit area is increased by increasing the voltage of the peripheral high-frequency power supply 40B higher than the central high-frequency power supply 40A. Since it is set higher than that, the plasma concentration and the radical concentration in the peripheral plasma generation chamber 14B are higher than in the center plasma generation chamber 14A. Therefore, the radical concentration difference is reflected also in the processing chamber 16, and the radical concentration in the peripheral part becomes higher in the processing chamber 16 than in the central part thereof. Will be promoted. as a result,
Since a larger amount of deposited film tends to be deposited on the peripheral portion of the wafer as compared with the conventional apparatus, it is possible to improve the uniformity of the film thickness over the entire surface of the wafer.

Further, since the plasma generation chamber 14 and the processing chamber 16 are separated from each other by the lower electrode 32 having the radical flow holes 34, the exhaust conductance in this portion is reduced, and the pressure difference between the two chambers 14, 16 is reduced. Can be set large. In addition, since the atmosphere in the processing chamber 16 is designed to be evacuated in the horizontal direction outward from the plurality of vacuum exhaust ports 28 provided around the processing chamber 16, the exhaust conductance is increased by that amount and the process pressure is reduced by several times. It can be reduced to about mmTorr. For this reason, the mean free path of the radical is lengthened, and the anisotropy in the flying direction can be increased. As a result, the embedding property is improved, and the step coverage can be improved. In this case, in order to set the pressure difference between the inside of the plasma generation chamber 14 and the inside of the processing chamber 16 to a desired pressure difference, the ratio of the opening area of the radical flow holes 34 of the lower electrode 32 is set to the lower electrode 32. It is desirable to set within a range of about 3 to 15% per unit area.

In this case, the lower electrode 32 and the mounting table 2
0 is set within a range from the radius to the diameter of the wafer W, for example, 10 when processing an 8-inch wafer.
It is preferable to set it within a range of about 20 cm. According to this, the vertical component of the radical incident on the surface of the wafer W is distributed more, and the anisotropy in the flying direction of the radical is increased by that amount, so that the step coverage can be further improved. Becomes FIG. 6 shows the results of a simulation in which the distance L1 was variously changed with the wafer diameter set to 20 cm. FIG. 6A shows L1 of 40 mm, FIG. 6B shows L1 of 100 mm, and FIG.
L1 is 180 mm. According to this, L1 is approximately 1
If it is smaller than 00 mm, the tendency of generation of voids increases, and if L1 exceeds 200 mm, the film forming speed is significantly reduced. Therefore, L1 is 100 to 200
It turns out that setting the value in the range of mm is relatively preferable.

Further, if the process pressure is set so that the mean free path of the radical is within a range of about 1 to 2 times the distance L1 between the lower electrode 32 and the mounting table 20, in particular. Since many radicals generated and flowing into the processing chamber 16 fly to the wafer surface without causing intermolecular collisions so frequently, the step coverage can be further improved. By applying a negative DC voltage to the grid electrode 52, negative electrons are confined in the plasma generation chamber 14, and positive charged particles are trapped near the grid electrode 52. Only a large amount of neutral radicals contributing to film formation flow into the processing chamber 16 and the surface of the wafer W is not charged, so that occurrence of charge-up damage can be suppressed. Become.

In place of the above-described voltage application method, the grid electrode 52, the lower electrode 32, and the wafer W may be set to the same potential, for example, the ground potential.
According to this, plasma can be drawn out relatively slowly at a heat velocity into the film formation chamber, and then the charged particles are separated by the difference in the sign of the charge, and a required amount of ions are deposited on the wafer with a desired energy. Irradiation becomes possible. Here, the radical concentration in the peripheral plasma generation chamber 14B is increased by increasing the voltage of the peripheral high-frequency power supply 44B, but instead, the amount of processing gas supplied to the peripheral plasma generation chamber 14B is reduced to a central value. The radical concentration may be set higher than that in the plasma generation chamber 14A and set higher.

In the above embodiment, the lower electrode 32
Although the diameters of all the radical flow holes 34 were set to be the same,
Not limited to this, for example, as shown in FIG. 7, the diameter D of the radical flow hole 34B corresponding to the peripheral plasma generation chamber 14B.
2 may be set to be larger than the diameter D1 of the radical flow hole 34A corresponding to the center plasma generation chamber 14A, and the ratio of the opening area per electrode unit area may be set to be large. According to this, the amount of radicals flowing down from the peripheral plasma generation chamber 14B is larger than that in the center plasma generation chamber 14A, so that the in-plane uniformity of the film thickness can be increased accordingly. In this case, the same high-frequency voltage may be applied to both the center and peripheral upper electrodes 30A, 30B. As described above, by setting the diameter D2 to be large, in the processing chamber 16, more radicals flow down to the peripheral portion than to the central portion. The sizes of the diameters D1 and D2 are set to values that generate ionization efficiency in the plasma generation chambers 14A and 14B such that the concentration distribution of radicals is optimal in the processing chamber 16. As an example, this size can be about 1/5 of the radical transport distance in the film formation chamber.

Next, the plasma processing apparatus of the second invention will be described. FIG. 8 is a configuration diagram showing a plasma processing apparatus of the second invention, and FIG. 9 is a schematic plan view of the apparatus shown in FIG. In the above-described apparatus of the first invention, the plasma generation chamber and the processing chamber are vertically divided into two stages. Instead, in the second invention, both chambers are concentrically divided. As shown
The plasma processing apparatus 60 has a processing container 62 made of aluminum and formed into a substantially cylindrical body having a large diameter. In the processing chamber 62, a central area is formed as a processing chamber 64, and a ring-shaped area is formed concentrically as a plasma generation chamber 66 on the outer periphery thereof. Further, the center of the bottom of the processing container 62 is projected downward into a cylindrical shape, and a transfer chamber 65 is defined therein. In the transfer chamber 65, like the first invention, the mounting table 6 is provided.
8, a support 70 and a bellows 72 are provided.
9 is also provided with a gate valve 74.

The ceiling of the processing chamber 64 projects upward in a conical cross section, and is formed as a vacuum exhaust port 76. A ring-shaped upper electrode 76 and a lower electrode 78 are provided above and below the plasma generation chamber 66, respectively.
0, 82. A high-frequency power source 85 for generating, for example, 13.56 MHz plasma is connected between the upper and lower electrodes 76 and 78. Also,
As shown in FIG. 9, a plurality of gas introduction ports 84 arranged at equal intervals along the circumferential direction, and in the illustrated example, four gas introduction ports 84 are provided on the side wall of the processing container 62. A processing gas whose flow rate is controlled by a flow rate controller 86 such as a mass flow controller is introduced into the gas inlet 84. On the inner and outer sides of the plasma generation chamber 66, ring-shaped partitioning plates 86 and 88 made of, for example, ceramics having high insulating properties are provided, and the plasma generation chamber 66 is partitioned. This partition plate 8
A large number of radical circulation holes 90, 92 are formed in substantially the entire surfaces of the tubes 6, 88, respectively. The slight gap between the outer peripheral partition plate 88 and the container side wall is, for example, 5 mm wide.
The buffer space 94 is formed as a ring-shaped buffer space 94 having a diameter of about cm. The gas introduced from the gas inlet 84 also flows through the buffer space 94 in the circumferential direction and is diffused into the processing chamber 64 so as to extend in the outer circumferential direction. To supply the gas uniformly.

In the buffer space 94, two ring-shaped outer grids 96A and 96B which are formed in a mesh shape and are slightly separated from each other are provided above and below the container via an insulator 98. Also, inside the partition plate 86 on the inner periphery, two ring-shaped inner grids 100A and 100B which are formed in a mesh shape and are slightly separated from each other are supported on the upper and lower sides of the container via the insulator 102. Is provided. And the outer grid 96A,
By applying an AC voltage of a predetermined frequency having a phase difference of, for example, 180 degrees between the inner grid 96B and the inner grids 100A and 100B, the charged particles are reciprocally oscillated in the plasma generation chamber 66 and are confined. Also,
A ring-shaped baffle plate 104 extending downward to about half the height in the processing chamber 64 is provided on the further inner ceiling of the inner grids 100A and 100B, that is, around the ceiling of the processing chamber 64. ing. The ceiling of the processing chamber 64 (the partition wall of the vacuum exhaust port 76) is grounded.

Next, the operation of the present embodiment configured as described above will be described. First, an unprocessed wafer W is mounted on the mounting table 68 in a state where the mounting table 68 is lowered as indicated by a virtual line, and thereafter, the unprocessed wafer W is raised to a film forming position. Silane, oxygen, Ar gas, etc., whose flow rates are controlled, are introduced from the respective gas introduction ports 84, and the introduced processing gas diffuses in the circumferential direction in the buffer space 94 while the radical flow holes 92 of the partition plate 88 are formed. Flows through the ring-shaped plasma generation chamber 66 through the upper and lower electrodes 7.
Plasma is generated by the high-frequency voltage applied between 6, 6 and 78, and the plasma is activated to generate radicals of the processing gas. The generated radicals flow almost uniformly from the circumferential direction into the processing chamber 64 through the radical circulation holes 90 of the partition plate 86 located inside. Then, an SiO ₂ film is deposited on the surface of the wafer W by the reaction of the radical. The gas that has flowed into the processing chamber 64 is evacuated upward through a vacuum exhaust port 76 provided in the ceiling, and the inside of the processing container 62 is maintained at a predetermined process pressure.

Here, in the case of this embodiment, the processing chamber 64
The plasma generating chamber 66 is arranged in a ring around the periphery of the processing chamber 64, and the generated radicals are introduced almost uniformly from the entire circumference of the processing chamber 64 toward the center thereof. Therefore, the radical concentration tends to decrease. The concentration of radicals in the peripheral portion of the wafer becomes relatively high. As a result, it is possible to improve the uniformity of the plasma processing, that is, the in-plane uniformity of the film thickness in this case. Also, as described above, the plasma generation chamber 6
6 and the processing chamber 64 are clearly separated from each other.
This can prevent the influence on the wafer processing. Further, since the baffle plate 104 is provided around the ceiling of the processing chamber 64, the radicals flowing into the processing chamber 64 can be directly discharged from the vacuum exhaust port 76 without contributing to the reaction. As a result, almost all radicals flow once near the surface of the wafer W, and the film formation rate can be improved accordingly.

Further, outer and inner grids 96A, 96B and 100A, 1A, 1B surrounding the inner and outer circumferences of the plasma generation chamber 66, respectively.
By applying an alternating voltage of a predetermined frequency during 00B and causing the charged particles to reciprocate and vibrate between them,
By preventing this outflow, the generation efficiency of plasma and radicals can be increased. Further, it is possible to prevent charge-up damage from occurring on the wafer W. Furthermore, the opening area of each of the radical flow holes 90 and 92 of the partition plates 86 and 88 that partition the plasma generation chamber 66 is
It may be determined based on the exhaust conductance such that the pressure difference between the inside and the processing chamber 64 becomes an optimum value. in this case,
The pressure ratio and the opening area ratio are closely related. Although four gas inlets 84 are provided here, the buffer space 9
If the width of 4 can be sufficiently secured to ensure the uniformity of the gas flowing into the plasma generation chamber 66, the number of the gases can be reduced,
For example, one may be provided.

In this embodiment, the upper surface level of the mounting table 68 and the bottom surface level of the plasma generation chamber 66 are set to be substantially the same during the film forming process. However, the present invention is not limited to this. For example, as shown in FIG. In addition, the upper surface level of the mounting table 68 is considerably higher than the lower surface level of the plasma generation chamber 66,
For example, the film formation process may be performed on the wafer W in a state where the wafer W is positioned about 3 to 5 cm below and falls into a concave shape. According to this, stagnation of radicals occurs in the space defined by the concave portion 106, and as a result, the in-plane uniformity of the film thickness can be further improved. FIG.
In the example of the apparatus shown in FIG.
6, but is not limited to this. As shown in FIG. 11, a plurality of, for example, four vacuum exhaust ports 76 having the same structure as that described in FIG. It may be provided. In this case, the same operation and effect as described above can be exhibited. Also,
In this case, it is not necessary to provide the baffle plate 104 shown in FIG.

[0030] In the above description a case has been described using silane and oxygen and Ar gas as a processing gas as an example, this not limited to the gas species is of course, still not the deposition of SiO ₂ The present invention can be applied to the case of forming other insulating films, metal films, metal oxide films, and the like. Further, the object to be processed is not limited to a semiconductor wafer, and may be used for an LCD substrate, a glass substrate, and the like.

[0031]

As described above, according to the plasma processing apparatus and the plasma processing method of the present invention, the following excellent operational effects can be obtained. Claims 1, 2,
According to the inventions defined in 4 and 16, the plasma generation chamber includes:
It is concentrically divided into a plurality of sections, and the radicals in the peripheral portion of the processing chamber are set to have a higher concentration than that in the central portion. For example, the deposited film tends to be thickly deposited. For this reason,
It is possible to improve the uniformity of the processing as a whole, that is, the in-plane uniformity of the film thickness in the case of film formation. According to the third aspect of the present invention, the atmosphere in the processing chamber is evacuated in the horizontal direction as it is, so that the exhaust conductance is increased by that amount, the process pressure is further reduced, and the anisotropy in the direction in which radicals fly is increased. And increase step coverage. According to the invention defined in claim 5, the component near the vertical direction of the radical incident on the object to be processed is increased, that is, the anisotropy in the flying direction of the radical is increased, and the step coverage is further improved. Can be. According to the invention defined in claim 6, since many generated radicals fly to the object without frequently causing intermolecular collisions, the anisotropy in the incident direction of the radicals is kept high. Thus, step coverage can be improved. According to the invention defined in claim 7, since the plasma density of the plasma generation chamber located at the peripheral portion is increased, radicals having a higher concentration than the central portion can flow down from the plasma generation chamber into the processing chamber, Therefore, the in-plane uniformity of the processing, for example, the in-plane uniformity of the film thickness can be improved. According to the invention defined in claim 8, since the amount of radicals flowing down from the plasma generation chamber located at the peripheral portion is larger than that at the central portion, the in-plane uniformity of processing, for example, the film thickness Can be improved in-plane uniformity. According to the invention defined in claim 9, for example, if a DC fixed bias is applied to the grid electrode, it is possible to minimize the incidence of charged particles such as electrons and ions on the object to be processed and to reduce only radicals. By making the light incident, generation of charge-up damage can be suppressed. Claims 10, 13, 14, 17
According to the invention defined in (1), since the radicals act so as to flow toward the center rather than the peripheral portion of the object to be processed, compared with the conventional apparatus flowing from the central portion toward the peripheral portion, In-plane uniformity, for example, in-plane uniformity of film thickness can be improved. In addition, since the plasma generation chamber and the processing chamber are clearly separated from each other, even if the plasma itself has, for example, non-uniformity in concentration, it is possible to prevent the non-uniformity from directly affecting the processing of the object to be processed. be able to. According to the invention defined in claim 11, the processing gas or the like can be uniformly introduced into the plasma generation chamber. According to the invention defined in claim 12, it is possible to prevent the charged particles from flowing out of the plasma generation chamber, to enhance the plasma generation efficiency, and to suppress the object to be processed from being charged-up damaged. can do. According to the invention as defined in claim 15, the discharge of radicals is prevented by the baffle plate and the concentration of radicals in the processing chamber increases, so that the processing efficiency can be increased accordingly.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a plasma processing apparatus of a first invention.

FIG. 2 is a diagram showing a state when a mounting table is lowered in the plasma processing apparatus shown in FIG. 1;

FIG. 3 is a plan view showing an arrangement state of exhaust ports.

FIG. 4 is a diagram showing a supply state of a processing gas and an application state of a high-frequency power supply.

FIG. 5 is a plan view showing a lower electrode.

FIG. 6 is a diagram showing a simulation result of the dependence of the embedding state on the distance between the lower electrode and the mounting table.

FIG. 7 is a view showing a modification of the radical flow hole of the lower electrode.

FIG. 8 is a configuration diagram showing a plasma processing apparatus of the second invention.

9 is a schematic plan view of the device shown in FIG.

FIG. 10 is a diagram showing a part of a modification of the second invention.

FIG. 11 is a view showing another modification of the second invention.

FIG. 12 is a schematic configuration diagram showing a conventional parallel plate type plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Plasma processing apparatus 12 Processing container 14 Plasma generation chamber 16 Processing chamber 20 Mounting table 28 Vacuum exhaust port 30 Upper electrode 30A Center upper electrode 30B Peripheral upper electrode 32 Lower electrode 34 Radical circulation hole 42 Partition wall 44A Center high frequency power supply 44B Peripheral High frequency power supply 52 Grid electrode W Semiconductor wafer (workpiece)

Claims (17)

[Claims] 1. A plasma generation chamber for generating a plasma therein to generate radicals sandwiched between an upper electrode and a lower electrode connected to a high frequency power supply, and a radical provided below the plasma generation chamber and flowing down And a processing chamber which is made evacuable to perform a predetermined plasma processing on the object to be processed, wherein the plasma generation chamber is divided into a plurality of concentric shapes, and a central portion of the processing chamber A plasma processing apparatus characterized in that the concentration of the radical in a peripheral portion is set high. 2. The plasma processing apparatus according to claim 1, wherein the lower electrode has a plurality of radical flow holes for allowing the radicals to pass therethrough. 3. The plasma processing apparatus according to claim 1, wherein a plurality of vacuum exhaust ports for evacuating the processing chamber are formed in a side wall that partitions the processing chamber. 4. The plasma processing apparatus according to claim 1, wherein a processing gas is individually supplied to each of the plurality of divided plasma generation chambers. 5. A distance between the lower electrode and a mounting table for mounting the object to be processed is set to a length within a range from a radius to a diameter of the object to be processed. The plasma processing apparatus according to claim 1, wherein 6. The pressure in the processing chamber is set such that the mean free path of the radical falls within a range of about 1 to 2 times a distance between the lower electrode and the mounting table. The plasma processing apparatus according to claim 5, wherein 7. An upper limit electrode of the plurality of divided plasma generation chambers is divided into a plurality corresponding to the plasma generation chamber, and a high-frequency voltage applied to the upper limit electrode is located at a peripheral portion rather than a central portion. 7. The plasma processing apparatus according to claim 1, wherein is set to be large. 8. The method according to claim 1, wherein an opening area per unit area of a radical flow hole formed in the lower electrode is set to be larger at a peripheral portion than at a central portion. The plasma processing apparatus according to any one of the above. 9. The plasma processing apparatus according to claim 1, wherein a grid electrode is disposed in the processing chamber. 10. A plasma processing apparatus for performing predetermined plasma processing on an object to be processed, comprising: a cylindrical processing chamber containing the object to be processed and capable of being evacuated; A ring-shaped plasma generation chamber that is formed concentrically and is sandwiched between an upper electrode and a lower electrode connected to a high-frequency power source to generate plasma inside and generate radicals, A plasma processing apparatus, comprising: a partition plate formed between the plasma generation chamber and a plurality of radical circulation holes. 11. The ring-shaped plasma generation chamber includes:
11. The plasma processing apparatus according to claim 10, wherein a plurality of gas inlets are provided at predetermined intervals along the outer peripheral direction. 12. The plasma processing apparatus according to claim 10, wherein a grid electrode is provided on at least the inner peripheral side of the inner peripheral side and the outer peripheral side of the ring-shaped plasma generation chamber. 13. The plasma processing apparatus according to claim 10, wherein a vacuum exhaust port for evacuating the inside of the processing chamber is formed in a ceiling portion of the processing chamber. 14. The processing object in the processing chamber is supported at a position lower than a bottom level of the plasma generation chamber, and a vacuum exhaust port for evacuating the inside of the processing chamber is provided on a side wall of the processing chamber. The plasma processing apparatus according to any one of claims 10 to 12, wherein is formed. 15. The plasma processing apparatus according to claim 13, wherein a ring-shaped baffle plate is provided downward around a ceiling of the processing chamber. 16. A plasma processing method for performing plasma processing on an object to be processed, wherein a step of generating plasma in a concentrically divided plasma generation chamber to generate radicals, A process in which radical concentration is introduced into a processing chamber located below in a state where a radical concentration is higher in a peripheral portion than in a central portion of the processing object, and plasma processing is performed on the processing object. Method. 17. A plasma processing method for performing plasma processing on an object to be processed, wherein: a step of generating plasma in a ring-shaped plasma generation chamber to generate radicals; Performing a plasma process on the object by introducing the object into a processing chamber located inside a generation chamber.