JP3260168B2 - Plasma processing equipment - Google Patents

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 used in a semiconductor manufacturing process and the like, and more particularly to a magnetron plasma etching apparatus.

[0002]

2. Description of the Related Art Conventionally, as a magnetron plasma processing apparatus, for example, a dry etching apparatus and a thin film forming apparatus used for manufacturing a semiconductor device are known. In this type of magnetron plasma processing apparatus, plasma is generated in a processing chamber of the apparatus, and ions in the plasma,
A desired process (etching, thin film formation, or the like) is performed using the action of radicals, electrons, or the like.

Hereinafter, such a magnetron plasma processing apparatus will be described with reference to the magnetron plasma etching apparatus shown in FIG.

In FIG. 1, a process chamber 40 is provided.
Are configured to be able to be evacuated and to be capable of introducing an etching gas. Inside the process chamber 40, a plate-shaped mounting electrode 42 on which the wafer 10 as an object to be processed is mounted and a plate-shaped upper electrode 46 are provided in parallel. The mounting electrode 42 and the upper electrode 46 are both formed of a conductive material, and the upper electrode 46 is grounded, for example, and high frequency power (380 KHz or 13.56 MHz, for example) is applied to the mounting electrode 42. An output RF power supply 44 is connected. With such a configuration, it is possible to generate plasma facing the wafer 10 between the parallel plate electrodes of the upper electrode 46 and the placement electrode 42 by the cathode coupling (RIE) method. The electrons or neutrons in the plasma react with the silicon compound forming the wafer 10 or physically act thereon, whereby the wafer 10 is etched.

In this device, the two permanent magnets 38 supported by the yoke 38b are rotated about the rotation shaft 38a, thereby forming the upper electrode 46 and the mounting electrode 42 as shown by broken lines in FIG. A magnetic field having a horizontal component is formed between the upper electrode 46 and the mounting electrode 42 during the period. According to Fleming's left-hand rule, the action of the electric field generated between the upper electrode 46 and the mounting electrode 42 and the magnetic field component orthogonal to the electric field causes the cycloid motion of the electrons in the directions orthogonal to each other. This is to increase the frequency of collision between electrons and gas molecules. As a result, the amount of plasma generated can be increased, and therefore, the etching rate can be increased.

[0006]

In a plasma etching apparatus, it is required that the etching rate be uniform over the entire surface of the silicon wafer 10. However, when the above-described conventional apparatus is used, unevenness in the wafer surface of the etching process occurs due to the following reasons.

(1) The electrons move in a direction orthogonal to the magnetic field due to the cycloid movement of the electrons, so that the electron density becomes extremely high in a part of the outer peripheral portion of the wafer 10 and damages the wafer. The ions in the plasma collide with the surface of the wafer 10 due to the action of the ion sheath generated between the upper electrode 46 and the mounting electrode 42. At this time, some of the colliding ions are implanted into the wafer 10 and cause damage to the wafer. When the electron density in the plasma is high, the number of ions implanted into the wafer 10 increases, and the damage increases. In the magnetron etching apparatus, since the magnetic field is rotated, the damaged portion is the entire outer peripheral portion of the wafer 10.

(2) The concentration of ions of the etching gas (eg, Cl) is higher in the space region near the periphery than in the space region near the center of the silicon wafer 10. The reason that the concentration of the etching gas ions is higher in the space region near the peripheral portion than in the space region near the center of the silicon wafer 10 is that the flow (exhaust) of the reacted gas generated by the etching reaction (exhaust) is high. It is considered that one factor is that it is slow near the center of the silicon wafer 10 and fast near the periphery.

Such a problem is not limited to a magnetron plasma etching apparatus, but is common to a magnetron plasma sputtering apparatus and a plasma CVD apparatus.

The present invention has been made in view of such a conventional technique, and an object of the present invention is to provide a plasma processing apparatus capable of performing a uniform plasma processing in a plane of an object to be processed.

[0011]

The present invention has a first electrode on which an object to be processed is mounted and a second electrode facing the first electrode, wherein the first electrode is placed in a processing gas atmosphere. In a plasma processing apparatus that generates plasma by generating an electric field between the first electrode and the second electrode and processes the object by the action of the plasma, A conductive ring which is controlled so as to have substantially the same potential and is provided near a peripheral portion of the object to be processed, and an outer diameter of the conductive ring is larger than a diameter of the object to be processed; It is characterized by.

Here, the electric resistance of the conductive ring is:
It is desirable that the electric resistance be smaller than the electric resistance of the object.

[0013]

According to the present invention, the outer diameter of the conductive ring having substantially the same potential as that of the first electrode on which the object is placed is formed larger than the diameter of the object. Accordingly, the same effect as substantially increasing the apparent area of the object to be processed can be obtained. The ion concentration of the processing gas tends to be high in the peripheral part of the processing object, but by increasing the apparent area of the processing object by the conductive ring, the adverse effect that occurs in the peripheral part of the processing object can be reduced. Sex ring. In other words, by expanding the plasma generation region over the conductive ring, a high ion concentration region can be generated on the conductive ring around the target object.

According to the second aspect of the present invention, since the electric resistance of the conductive ring is smaller than the electric resistance of the object to be processed, the electrons floating in the plasma generation region on the conductive ring are taken in, so that the density of the electrons is increased. Can be uniformed around the object to be processed. When the ion distribution around the object to be processed is uniform, damage to the object to be processed is reduced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as an embodiment of the present invention, a case where the present invention is applied to a magnetron plasma etching apparatus will be described as an example.

FIG. 2 is a sectional view showing a magnetron plasma etching apparatus according to a first embodiment of the present invention together with a transport mechanism.

A load lock chamber 2 is connected to both sides of the process chamber 1. The two load lock chambers 2 communicate with the process chamber 1 through the opening 3. A gate 3a is provided in each opening 3, and can be opened and closed freely. Each load lock chamber 2 also has another opening 4 opposite the opening 3. A gate 4a is provided in the opening 4 and can be opened and closed freely.
Each opening 4 is arranged so as to face the cassette 7 that stores the wafer 10.

An air supply pipe 5 for introducing an inert gas (eg, nitrogen) and an exhaust pipe 6 connected to a vacuum pump are connected to each load lock chamber 2. Therefore,
Each load lock chamber 2 can change the internal atmosphere to a high reduced pressure atmosphere and an inert gas atmosphere independently of the process chamber 1. In each of the load lock chambers 2, a transfer device 100 described later is provided. The transfer device 100 transfers the wafer 10 between the cassette 7 and the process chamber 1. In this arrangement of the etching and load lock chambers, the wafer 10 is usually loaded into the process chamber 1 from one of the left and right sides,
After processing in the same chamber 1, it is unloaded from the other side. In another embodiment, the wafer 10 may be loaded and unloaded by using only one transfer mechanism.

FIG. 1 is an enlarged sectional view showing a main part of the apparatus of the first embodiment.

The wafer 10 to be processed is mounted and fixed on the upper surface of the first susceptor 12. As a method for mounting and fixing, for example, an electrostatic chuck (not shown) method can be used. In this method, the wafer 10 is suctioned and fixed by Coulomb force. The first susceptor 12 is detachably fixed to the upper surface of the second susceptor 14. The reason why the susceptor is divided into two is that only the upper first susceptor 12 needs to be replaced when the susceptor is contaminated, thereby facilitating maintenance.

In this embodiment, the diameter of the first susceptor 12 is 180 mm, and this dimension is
Corresponds to the case where a wafer having a diameter of 150 mm is used.

The side and bottom surfaces of the first susceptor 12 and the second susceptor 14 are formed of an insulating member 16 made of ceramic.
Covered by On the lower surface of the insulating member 16, a liquid nitrogen storage section 20 as a cooling section is provided. The bottom surface of the inner wall of the liquid nitrogen accommodating portion 20 is formed, for example, in a porous manner so that nucleate boiling can be caused, and the liquid nitrogen inside can be maintained at -196 ° C.

The process chamber 1 for forming a reaction chamber is formed by an upper chamber portion 30 and a lower chamber portion 32.

The lower chamber portion 32 has a bottomed cylindrical portion that exposes only the wafer mounting surface of the first susceptor 12 into the chamber and covers another portion of the first susceptor 12. That is, the lower chamber portion 32
Has a side wall 32a that covers the first susceptor 12, the second susceptor 14, the ceramic insulating member 16 and the side surface of the liquid nitrogen accommodating portion 20, and a support wall 32b that supports the side wall 32a. .

On the other hand, the upper chamber portion 30 is formed in a cylindrical shape so as to cover the periphery of the side wall 32a of the lower chamber portion 32, and the lower end thereof is connected and fixed to the lower chamber portion 32. The upper chamber portion 30 has a surface 30 a facing the upper surface of the first susceptor 12. Note that an etching gas, for example, Cl ₂ is introduced from a supply source S via a pipe 33 connected to the upper chamber portion 30.

The inside of the reaction chamber 1 composed of the upper chamber portion 30 and the lower chamber portion 32 can be evacuated via a pipe 34 by a pump P.

As shown in FIG. 1, the second susceptor 14, the insulating member 16 and the liquid nitrogen accommodating portion 20 are each provided with a through hole, and a pipe 36 is disposed in the through hole. On the bonding surface between the wafer 10 and the first susceptor 12,
Voids are present due to minute irregularities on the back surface of the wafer 10 and cause uneven temperature of the wafer 10. However, through the pipe (not shown) provided in the first susceptor 12, a predetermined pressure H
The e-gas is filled to prevent such temperature unevenness.

In this embodiment, the upper chamber portion 3
0 is grounded, while the first and second susceptors 12, 14
Is connected to the RF power supply 44, and two electrodes are configured.
That is, the surface 30a of the upper chamber portion 30 functions as an anode electrode, and the surface of the first susceptor 12 functions as a cathode electrode, thereby forming an RIE type magnetron plasma etching apparatus. Then, an etching gas is introduced in a state where the inside of the chamber is evacuated, and plasma is generated between the opposed electrodes by the etching gas. As described above, in this embodiment, since the surface 30a of the upper chamber portion 30 is used as an anode electrode, the configuration of the apparatus can be simplified, and a permanent magnet 38 described later is connected to the upper chamber portion 30. Can be placed outside. Further, by disposing the permanent magnet 38 outside the upper chamber portion 30 in this manner, the volume of the reaction chamber can be reduced, so that the load on the vacuum pump P connected to the pipe 34 can be reduced. Alternatively, the time required for evacuation can be reduced.

In this embodiment, as described above, the anode electrode (upper chamber portion 30) is connected to the electrode portion (first surface 30) corresponding to the cathode electrode (first susceptor 12).
a), and an electrode portion (first surface 30b) located at right angles to the cathode electrode. Therefore, wafer 1
At the periphery of 0, an electric field of a horizontal component is generated as shown by a solid line in FIG.

The rotation of the permanent magnet 38 causes the surface 30 a of the upper chamber portion 30 and the first susceptor 12
And a rotating magnetic field is formed between them. The reason for forming this magnetic field is that the electric field generated between the upper chamber portion 30 and the first susceptor 12 and the magnetic field component orthogonal to this electric field act on each other, and are orthogonal to each other according to Fleming's left-hand rule. This is for causing cycloidal motion of electrons in the direction, thereby increasing the frequency of collision between electrons and gas molecules.

The magnetic field formed by the permanent magnet 38 is
As shown by the broken line in FIG. 1, the wafer 10 is substantially horizontal above the center of the wafer 10, and the closer to the periphery, the greater the inclination of the arc (that is, the greater the vertical component). In contrast, the electric field formed by both electrodes is
As described above, since the anode electrode has the electrode portion parallel to the cathode electrode and the electrode portion perpendicular to the cathode electrode, only the component substantially perpendicular to the central portion of the wafer 10 is obtained. Then, the horizontal component increases. For this reason,
The cycloid motion of the electrons caused by the orthogonality of the magnetic field and the electric field is made uniform in the central portion and the peripheral portion of the wafer 10. That is, with such a configuration, in the apparatus of the present embodiment, the amount of plasma generated is made uniform at the central portion and the peripheral portion of the wafer 10, and the in-plane uniform processing of the wafer becomes possible.

On the upper surface of the lower chamber portion 32,
A conductive ring 22 made of a conductor, such as carbon, is placed along the outer periphery of the wafer 10. The ring 22 is mounted in a concave portion formed on the upper part of the ceramic insulating member 16.

The ring 22 is in electrical contact with the susceptor 12 and is insulated from the lower chamber portion 32. The conductive ring 22 is formed from a substance having a lower electric resistance than the object to be processed. For example, non-metallic SiC, carbon, or the like can be used for the silicon wafer 10.
The conductive ring 22 plays a role of making the electron density uniform around the wafer 10 by taking in the electrons floating in the plasma generation region on the conductive ring 22. When the ion distribution around the wafer 10 becomes uniform, the damage to the wafer 10 decreases.

The outer diameter of the ring 22 is equal to that of the first susceptor 12.
And is formed larger than the diameter of the wafer 10. Therefore, the same effect as substantially increasing the apparent area of the wafer 10 can be obtained. As described above, the wafer 10
Tends to have a high ion concentration of the etching gas (for example, Cl). But like this, ring 2
2 to increase the apparent area of the wafer 10 to reduce the adverse effects that may occur at the periphery of the wafer 10.
It is possible to impose it. In other words, by extending the plasma generation region onto the conductive ring 22,
A high Cl concentration region can be created on the ring 22 around the wafer 10.

FIG. 3 shows a conductive ring 2 according to the first embodiment.
It is a figure which shows the example of a change of No. 2. In the examples of FIGS. 7A and 7B, the surface position of the conductive ring 22 is flush with the surface of the wafer 10 or indicates a height position protruding above the surface. In each case, the conductive ring 22
Is the insulating ring 3 for the lower chamber portion 32
Insulated by 2c. Further, in any of the examples, the conductive ring 22 is in a non-contact state with the first susceptor 12, but the conductive ring 22 is controlled to have substantially the same potential as the first susceptor 12. In the example shown in FIG. 3C, the arrangement is such that the surface of the conductive ring 22 is flush with the surface of the first susceptor 12. In this case, the conductive ring 22 is insulated from the lower chamber portion 32 by the insulating ring 32 c, but is conductive when the inner wall surface of the conductive ring 22 contacts the first susceptor 12.

FIGS. 6A and 6B are views showing another modification of the conductive ring 22 according to the first embodiment. FIG.
In the example of (A), the upper surface of the ring 22 is aligned with the main surface of the wafer 10. In the example of FIG. 6B, the upper surface of the ring 22 is located above the main surface of the wafer 10.

As described above, by providing the conductive ring 22 detachably, when the ring 22 is contaminated,
Only the ring 22 needs to be replaced, and maintenance of the apparatus can be facilitated. [Experiment 1] In order to determine the effect of the conductive ring 22, damage to the wafer 10 was examined. Here, an E ² PROM evaluation method was used as a damage evaluation method.

The E ² PROM evaluation method is to damage a wafer 10 ′ on which an E ² PROM is already formed in place of an original object (eg, a silicon wafer on which a resist is formed). In this method, the magnitude of the damage received by the E ² PROM is compared by comparing the threshold voltage of the E ² PROM with the threshold voltage before the damage is given. E ² PR
When the OM is damaged, the electron density in the floating gate increases, and thus the threshold voltage V _Th increases. Accordingly, by comparing the threshold voltage with the threshold voltage before damaging, it is possible to determine the magnitude of the received damage E ² PROM.

FIG. 4 shows a wafer 1 on which an E ² PROM is formed.
FIG. 4 is a top view conceptually showing 0 ′ and is a diagram for explaining a method of performing evaluation by an E ² PROM evaluation method.

At a plurality of positions on the line AB shown in FIG. 4, a threshold voltage V _Th1 before damage and a threshold voltage V _Th2 after damage are measured, and the difference between the two is measured. ΔV _Th (=
(V _Th2 −V _Th1 ) was evaluated.

The evaluation was performed in a state where the S pole and the N pole were fixed at the positions shown in FIG. 4 without rotating the permanent magnet 38. As a result, as shown in FIG. 4, a high electron density region was formed only in a specific region on the peripheral portion of the wafer 10.

In the present embodiment, for the purpose of comparison, the same evaluation was performed for a case where an insulating ring made of quartz was used instead of the conductive ring 22.

FIG. 5 is a graph showing the results of the evaluation. In the figure, the horizontal axis indicates the position (unit: millimeter) of the wafer 10 ′ on the line AB, and the vertical axis indicates ΔV
_Th (unit: volt).

As can be seen from FIG. 5, ΔV _Th increases in a region where the electron density in the plasma is high, regardless of whether the ring is conductive or insulating. However, when the insulating ring was used, ΔV _Th was close to 8 [V] at the maximum, whereas when the conductive ring was used, it was about 2 [V] at the maximum. As described above, in the magnetron etching apparatus of the present embodiment, by using the conductive ring 22, it was possible to drastically reduce ΔV _Th as compared with the case where the insulating ring was used. This phenomenon has a remarkable effect when etching the polysilicon.

FIG. 7 is an enlarged sectional view showing a main part of a magnetron plasma etching apparatus according to a second embodiment of the present invention. In the figure, parts corresponding to those of the apparatus of the first embodiment shown in FIG.

As shown in FIG. 8, the second embodiment differs from the first embodiment in that the conductive ring 22 is disposed on the insulating ring 32C. Insulation ring 32
C has substantially the same outer diameter as the support wall 32b of the lower chamber portion 32.
6 has approximately the same inner diameter.

The conductive ring 22 is in electrical contact with the susceptor 12 and is insulated from the lower chamber portion 32 as in the first embodiment. The conductive ring 22 is formed from a substance having a lower electric resistance than the object to be processed. For example, for the silicon wafer 10, non-metallic Si
C, carbon, etc. can be used. Further, the outer diameter of the ring 22 is formed larger than the diameter of the first susceptor 12 and the wafer 10.

Therefore, even in the second embodiment, the first
The same advantages as those described in the embodiment can be obtained.

FIGS. 11A to 11D are views showing a modified example of the conductive ring 22 according to the second embodiment. FIG.
In the example of (A), the upper surface of the ring 22 is aligned with the main surface of the wafer 10. In the example of FIG. 11B, the upper surface of the ring 22 is located above the main surface of the wafer 10. FIG.
In the example of (C), the ring 22 is configured to be separable from the upper ring 22a and the lower ring 22b, the upper surface of the ring 22a is located above the main surface of the wafer 10, and the inner diameter thereof is smaller than that of the wafer 10. Has become. FIG.
In the example of (D), the thickness of the ring 22 is the second thickness in FIGS.
Same as Example, but with a larger outer diameter.

As described above, by providing the conductive ring 22 detachably, when the ring 22 is contaminated,
Only the ring 22 needs to be replaced, and maintenance of the apparatus can be facilitated. [Experiment 2] In order to investigate the relationship between the diameter of the conductive ring 22 and the etching rate of the wafer 10, the apparatus structure according to the second embodiment was used, and as shown in FIG. The following experiment was performed with only the following changes. Here, the carbon ring 22 and the silicon wafer 10
And were used. The etching was performed according to the measurement conditions shown in Table 1.

[Table 1] FIG. 9 is a graph showing the measurement results. In the figure, the horizontal axis represents the distance (unit: mm) from the center of the wafer 10, and the vertical axis represents the etching rate (unit: nm / min).

When a ring 22 having an outer diameter of 186 mm (ie, d = 18 mm in FIG. 8) was used, the etching rate was generally slower at the center of the wafer 10 and faster at the periphery. As a result of the measurement, the average value of the etching rate of the entire etched surface of the wafer 10 was 256.
7 nm / min, and the variation in etching rate
It was ± 10.7% based on this average value.

Outer diameter 200 mm (that is, d = 25 m
When the ring 22 of m) is used, the average value of the etching rate is 211.2 nm / min, and the variation in the etching rate is ± 6.4% based on this average value.
Met. Thus, the outer diameter is 1 mm larger than 186 mm.
By using the ring 22 that is 4 mm larger, the variation in the etching rate could be significantly reduced.

Outer diameter 220 mm (that is, d = 35 m)
When the ring 22 of m) is used, the average value of the etching rate is 198.7 nm / min, and the variation in the etching rate is ± 6.8% based on this average value.
Met. As described above, when the ring having the outer diameter of 220 mm was used, the variation in the etching rate could be reduced to substantially the same extent as when the ring 22 having the outer diameter of 200 mm was used.

An outer diameter of 250 mm (that is, d = 50 m)
When the ring of m) was used, the average value of the etching rate was 185.3 nm / min, and the variation in the etching rate was ± 15.3% based on this average value. As described above, when the carbon ring 22 having the outer diameter of 250 mm was used, the etching rate was faster in the center portion of the silicon wafer 10 and slower in the peripheral portion, contrary to the case where the carbon ring 22 of the standard size was used. . As a result, the variation in the etching rate was rather large.

As described above, the large-diameter carbon ring 22
By using, it was possible to make the etching rate of the silicon wafer 10 uniform. However, if the diameter of the carbon ring 22 was too large, the etching rate in the peripheral portion was too small, and the uniformity of the etching rate was rather deteriorated. Also, as the diameter of the carbon ring 22 was increased, the average value of the etching rate tended to decrease.

The variation in the etching rate is preferably set to ± 10% or less, more preferably ± 7% or less. In order to make the variation of the etching rate ± 7% or less, the outer diameter of the conductive ring 22 is set to be 130 to 150% of the diameter of the wafer 10 based on the above measurement result.
It is considered that the degree should be set. [Experiment 3] Next, in order to investigate the effect of the conductive ring 22 in a plasma etching apparatus without using a magnetron, a permanent magnet 38 was obtained from the apparatus of the second embodiment shown in FIG.
Was removed and the same measurement was performed. Here, a carbon ring 22 and a silicon wafer 10 were used. The etching and measurement conditions were the same as described above.

FIG. 10 is a graph showing the measurement results.
In the figure, the horizontal axis is the distance (unit: mm) from the center of the wafer 10, and the vertical axis is the etching rate (unit: nm / mi).
n).

When a ring 22 having an outer diameter of 186 mm (d = 18 mm) is used, the etching rate is generally
The speed was slow at the center of the wafer 10 and was fast at the periphery.
As a result of the measurement, the average value of the etching rate of the entire etched surface of the wafer 10 was 175.8 nm / min, and the variation in the etching rate was ± with respect to this average value.
35.1%.

When a ring 22 having an outer diameter of 200 mm (d = 25 mm) is used, the average value of the etching rate is 1
It was 33.6 nm / min, and the variation in the etching rate was ± 32.6% based on this average value.
As described above, by using a ring whose diameter is 14 mm larger than the outer diameter of 186 mm, variation in the etching rate could be reduced.

When a ring 22 having an outer diameter of 220 mm (d = 35 mm) is used, the average value of the etching rate is 1
08.0 nm / min, and the variation in the etching rate was ± 27.0% based on the average value.
As described above, when the ring having the outer diameter of 220 mm was used, the variation in the etching rate could be further reduced as compared with the case where the ring 22 having the outer diameter of 200 mm was used.

When a ring 22 having an outer diameter of 250 mm (d = 50 mm) is used, the average value of the etching rate is 8
It was 4.4 nm / min, and the variation in the etching rate was ± 11.2% based on this average value. As described above, when the ring 22 having the outer diameter of 250 mm was used, the variation in the etching rate could be reduced significantly.

As described above, it has been confirmed that the etching rate of the silicon wafer 10 can be made uniform by using the large-diameter carbon ring 22 even in a plasma etching apparatus that does not use a magnetron. . However, as compared with the case where the magnetron was used, the variation in the etching rate was large as a whole, and the average value of the etching rate was also slow.

As described above, the large-diameter carbon ring 22
By using, the variation of the etching rate,
It was able to be dramatically reduced. 9 and FIG.
As can be seen from the comparison with the above, by forming a rotating magnetic field in the plasma generation region using the permanent magnet 38, it is possible to increase the average value of the etching rate as compared with the case where the permanent magnet 38 is not used. At the same time, variations in the etching rate could be further reduced.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention.

For example, in the magnetron plasma etching apparatuses of the first and second embodiments, the surface 30a of the upper chamber portion 30 is used as an anode electrode, and the permanent magnet 38 is used as the upper chamber portion 30.
However, the anode electrode and the magnetic field generator may be arranged in the reaction chamber.

In this embodiment, the conductive ring 22 is formed of carbon, but may be formed of another conductive material such as SiC or A1. However, the conductive ring 22 is provided in order to take in electrons in the plasma and prevent the electrons from being injected into the wafer 10. It is desirable to use one having a small electric resistance. Further, only the surface may be formed of a conductive material, but in this case, the conductive surface of the ring and the susceptor 14 need to be electrically connected. The conductive ring 22 can be replaced with one having a different electric resistance according to the electric resistance of the wafer 10.

Further, in the above embodiment, since an RF power source is used as a power source for generating an electric field between the electrodes, a ring formed of an insulating material and a conductive film formed on the surface thereof may be used. It can be used as In the present invention, these rings are also referred to as “conductive rings”.

The substrate to be processed is polysilicon,
A wafer made of single crystal silicon, amorphous silicon, or the like can also be used. If it is an etching device,
A liquid crystal substrate can also be used as an object to be processed.

The present invention is not necessarily applied to a magnetron plasma etching apparatus, but can be applied to other magnetron plasma processing apparatuses such as a plasma CVD apparatus.

[0070]

According to the present invention, as described above, the conductive ring having substantially the same potential as the first electrode on which the object is placed is arranged around the object to be processed. The apparent area of the body can be substantially increased. As a result, a region that deteriorates the in-plane uniformity of the processing is assigned to the conductive ring, and the in-plane uniformity of the processing can be improved in the entire region of the processing target. According to the second aspect of the present invention, the floating electron is taken into the plasma generation region on the conductive ring by the conductive ring having lower electric resistance than the object to be processed, so that the electron density becomes uniform around the object. And the in-plane uniformity of the object to be processed can be further improved.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a main part of an apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing the magnetron plasma etching apparatus according to the first embodiment of the present invention together with a transport mechanism.

FIGS. 3A to 3C are cross-sectional views showing modified examples of the conductive ring in the device of the first embodiment.

FIG. 4 is a plan view showing a wafer 10 ′ on which an E ² PROM is formed and a high electron density region.

FIG. 5 shows an E ² PROM using the device of the first embodiment of the present invention.
4 is a graph showing the results of evaluation by an evaluation method.

FIGS. 6A and 6B are cross-sectional views showing another modification of the conductive ring in the device of the first embodiment.

FIG. 7 is an enlarged sectional view showing a main part of a magnetron plasma etching apparatus according to a second embodiment of the present invention.

FIG. 8 is an enlarged sectional view showing a portion near a conductive ring of the device of the second embodiment.

FIG. 9 is a graph showing the relationship between the diameter of a conductive ring and the etching rate of a wafer in the second embodiment.

FIG. 10 is a graph showing the relationship between the diameter of a conductive ring and the etching rate of a wafer when a permanent magnet is omitted from the apparatus of the second embodiment.

FIGS. 11A to 11D are cross-sectional views showing modified examples of the conductive ring in the device of the second embodiment.

FIG. 12 is a schematic sectional view showing a conventional magnetron plasma etching apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Wafer 12,14 Susceptor 20 Cooling part (liquid nitrogen storage part) 22 Carbon ring 30 Upper chamber portion 30a Upper surface of upper chamber portion 32 Lower chamber portion 34,36 Piping 38 Permanent magnet

Continuation of the front page (72) Inventor Masato Hiratsuka 2381 Kita Shimojo, Fujii-machi, Nirasaki City, Yamanashi Prefecture Inside Tokyo Electron Yamanashi Co., Ltd. (56) References JP-A-3-145725 (JP, A) JP-A-1- 200629 (JP, A) JP-A-61-119686 (JP, A) JP-A-52-123173 (JP, A) JP-A-1-298183 (JP, A) JP-A-4-356920 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/3065 C23C 14/34 C23C 16/509

Claims (4)

(57) [Claims] A first electrode on which an object to be processed is placed; and a second electrode facing the first electrode, wherein the first electrode and the second electrode are arranged in a processing gas atmosphere. A plasma processing apparatus that generates plasma by generating an electric field between the first electrode and the second electrode and processes the object by the action of the plasma. And a conductive ring provided on a peripheral portion of the object to be processed, the outer diameter of the conductive ring being 130 to the outer diameter of the object to be processed.
A plasma processing apparatus characterized by being 150%. 2. The plasma processing apparatus according to claim 1 , wherein an electric resistance of the conductive ring is smaller than an electric resistance of the object to be processed. 3. The method according to claim 1 , further comprising: means for forming a rotating magnetic field having a magnetic field component in a direction orthogonal to an electric field formed between the first electrode and the second electrode. A plasma processing apparatus characterized by the above-mentioned. 4. The plasma processing apparatus according to claim 1 , wherein the conductive ring is made of SiC or carbon.