JP3146171B2 - Plasma processing method and apparatus - 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 method and apparatus such as dry etching, sputtering, and plasma CVD, and more particularly to a high-frequency induction type plasma processing method and apparatus.

[0002]

2. Description of the Related Art In recent years, in response to miniaturization of semiconductor devices,
In dry etching technology, in order to realize processing with a high aspect ratio, etc., and in plasma CVD technology, in order to realize embedding with a high aspect ratio, plasma processing in a higher vacuum is required. For example, in the case of dry etching, when high-density plasma is generated in a high vacuum, the probability that ions collide with neutral gas particles or the like in an ion sheath formed on the substrate surface decreases, and the direction of the ions is reduced. The properties are aligned toward the substrate and the ionization degree is high, so that the ratio of the ion flux reaching the substrate to the incident particle flux of the neutral radical is increased. Therefore, the etching anisotropy is enhanced, and processing with a high aspect ratio becomes possible. In the case of plasma CVD, when high-density plasma is generated in a high vacuum, a fine pattern is buried and flattened by the sputtering effect of ions, and burying with a high aspect ratio becomes possible.

As one of plasma processing apparatuses capable of generating high-density plasma in a high vacuum, there is a high-frequency induction type plasma processing apparatus that generates plasma in a vacuum chamber by applying a high-frequency voltage to a coil. This type of plasma processing apparatus generates a high-frequency magnetic field in a vacuum chamber, generates an induced electric field in the vacuum chamber by the high-frequency magnetic field, accelerates electrons, and generates plasma. High-density plasma can be generated even in a vacuum, and a sufficient processing speed can be obtained.

FIGS. 6 and 7 show an example of a conventional high frequency induction type plasma processing apparatus. In FIG. 6, the vacuum chamber 1
The pump 3 is evacuated while introducing an appropriate gas from the gas supply means 2 into the inside, and high-frequency power is arranged along the dielectric plate 5 by the high-frequency power source 4 for the coil while maintaining the inside of the vacuum chamber 1 at an appropriate pressure. When supplied to the coil 6, the plasma is generated in the vacuum chamber 1 and the substrate 8 placed on the electrode 7
Can be subjected to plasma processing such as etching, deposition, and surface modification. At this time, as shown in FIG. 6, by supplying high-frequency power to the electrode 7 from the electrode high-frequency power supply 13, the ion energy reaching the substrate 8 can be controlled. Further, as shown in FIG. 7, the coil is formed in a multiple spiral shape.

Further, as shown in FIG. 6, a resistance heater 9 is provided and connected to a heater power supply 12 for supplying a current to the resistance heater 9. The resistance heater 9 includes a heating element 100 and a thin heat insulating material sandwiching the heating element 100. FIG. 8 shows a plan view of a heating element 100 constituting a conventional resistance heater. As shown in FIG. 8, the heating element 100 is laid almost uniformly over substantially the entire surface of the dielectric plate 5 except for the central portion. Heating element 1
The reason why 00 is laid almost uniformly over almost the entire surface except for the central portion of the dielectric plate 5 is to heat the dielectric plate 5 uniformly. , 200 ° C. ± 5 ° C., it has been confirmed that heating can be performed with extremely excellent soaking properties. By heating the dielectric plate 5, the dielectric plate 5
The thickness of the thin film deposited on the substrate can be significantly reduced,
Further, since the film quality can be made dense, generation of dust is suppressed. The maintenance frequency of the dielectric plate 5 is also significantly reduced. Further, even when the processing is repeated, the change in the thickness of the deposited film is small and the temperature of the dielectric plate 5 is kept at a high temperature. It has not changed much. Therefore, the atmosphere in the vacuum chamber 1, that is, the partial pressure of the reactive species is stable, and plasma processing with excellent reproducibility can be performed.

Further, in the plasma processing apparatus shown in FIG. 6, the heating element 100 acts as a Faraday shield,
Since the electrostatic coupling between the coil 6 and the plasma is weakened, it is possible to prevent the vacuum side of the dielectric plate 5 from being largely negatively charged. Therefore, the sputtering of the dielectric plate 5 due to the collision of the positive ions in the plasma toward the dielectric plate 5 at high speed can be prevented, the life of the dielectric plate 5 can be extended, and the dielectric material 5 can be used. Substrate contamination can be prevented. The effect of the Faraday shield is described in Leonard J. Mahoney et. Al., “Electron-densi
ty and energy distributions in a planar inductivel
y coupled discharde ", J. Appl. Phys. 76 (4), 1994.

[0007]

[0006] However, FIGS.
In the conventional method shown in FIG. 8, since the heating element is laid almost uniformly over almost the entire surface except for the center of the dielectric plate, the effect of the Faraday shield does not act on the center of the dielectric plate. However, there is a problem that the vacuum side of the center portion is sputtered, the life of the dielectric plate is short, and the substrate constituting the dielectric plate is contaminated. In order to avoid this problem, if the heating element is laid almost uniformly over almost the entire surface including the center of the dielectric plate,
The temperature of the central portion of the dielectric plate becomes higher than that of the other portions, causing a problem that the uniformity of heating is impaired. An object of the present invention is to provide a plasma processing method and apparatus capable of heating a dielectric plate with good thermal uniformity and preventing sputtering at the center of the dielectric plate in view of the above-mentioned conventional problems.

[0008]

In order to achieve the above object, the present invention is configured as follows. First of the present invention
According to the plasma processing method according to the aspect, the vacuum chamber is evacuated while supplying gas into the vacuum chamber, and while controlling the vacuum chamber to a predetermined pressure, high-frequency power is supplied to a coil disposed along the dielectric plate. In the plasma processing method of generating plasma in the vacuum chamber by supplying and processing a substrate mounted on an electrode in the vacuum chamber, a part other than the central part which is 5 to 20% of the entire area of the dielectric is provided. The substrate is processed in a state in which the dielectric plate is heated by the heater that generates heat and plasma is generated in a state where the electrostatic coupling between the coil and the plasma is weakened by the Faraday shield at the center portion. . According to the plasma processing method according to the second aspect of the present invention, in the first aspect, high-frequency power can be supplied to the electrode.

According to the plasma processing apparatus of the third aspect of the present invention, there are provided means for supplying a gas into the vacuum chamber, means for evacuating the vacuum chamber, and an electrode for mounting a substrate in the vacuum chamber. A coil for generating plasma in the vacuum chamber, a dielectric plate on which the coil is disposed, a unit for supplying high-frequency power to the coil, a resistance heater for heating the dielectric plate, and the resistance heater And a heater power supply for supplying current to the dielectric plate, wherein the heating element of the resistance heater is substantially evenly distributed over substantially the entire surface including the central portion which is 5 to 20% of the entire area of the dielectric plate. The heater is arranged so as to prevent current from flowing from the heater power supply to the heating element near the center of the dielectric plate.

According to the plasma processing apparatus of the fourth aspect of the present invention, there are provided means for supplying a gas into the vacuum chamber, means for evacuating the vacuum chamber, and an electrode for mounting a substrate in the vacuum chamber. A coil for generating plasma in the vacuum chamber, a dielectric plate on which the coil is disposed, a unit for supplying high-frequency power to the coil, a resistance heater for heating the dielectric plate, and the resistance heater And a heater power supply for supplying a current to the dielectric plate, wherein the heating element of the resistance heater is substantially uniformly distributed over substantially the entire surface except for the vicinity of the center, which is 5 to 20% of the total area of the dielectric plate. A low resistance conductor laid and laid near the center of the dielectric plate is connected to the heating element of the resistance heater. The fifth of the present invention
According to the plasma processing apparatus according to the aspect, in the third or fourth aspect, a means for supplying high-frequency power to the electrode can be provided. According to the plasma processing apparatus of the sixth aspect of the present invention, in any one of the third to fifth aspects, a part or all of the coil may have a multiple spiral shape.

[0011]

According to the plasma processing method according to the above aspect of the present invention, the vacuum chamber is evacuated while supplying gas into the vacuum chamber, and is arranged along the dielectric plate while controlling the vacuum chamber to a predetermined pressure. In the plasma processing method of generating plasma in the vacuum chamber by supplying high-frequency power to the coil and processing the substrate mounted on the electrodes in the vacuum chamber, the dielectric plate is heated by a heater that generates heat except at the center. In order to process the substrate in a state where the plasma is generated in a state where the coil is heated and the electrostatic coupling between the coil and the plasma is weakened by the Faraday shield at the center,
The dielectric plate can be heated with good uniformity, and sputtering near the center of the dielectric plate can be prevented. According to the plasma processing apparatus of the above aspect of the present invention, a means for supplying a gas into the vacuum chamber, a means for evacuating the vacuum chamber, an electrode for mounting a substrate in the vacuum chamber, A coil for generating plasma, a dielectric plate on which the coil is arranged, means for supplying high-frequency power to the coil, a resistance heater for heating the dielectric plate, and a current supply for supplying current to the resistance heater. In a plasma processing apparatus equipped with a heater power supply, the heating element of the resistance heater is laid almost evenly over almost the entire surface including the center of the dielectric plate, and current flows from the heater power supply to the heating element near the center of the dielectric plate. As a result, the dielectric plate can be heated with good thermal uniformity, and sputtering near the center of the dielectric plate can be prevented.

Further, according to the plasma processing apparatus according to the above aspect of the present invention, means for supplying gas into the vacuum chamber,
Means for evacuating the vacuum chamber, an electrode for mounting a substrate in the vacuum chamber, a coil for generating plasma in the vacuum chamber, a dielectric plate in which the coil is disposed, and means for supplying high-frequency power to the coil And, in a plasma processing apparatus having a heater power supply for supplying a current to the resistance heater and a resistance heater for heating the dielectric plate,
Since the heating element of the resistance heater is laid almost uniformly over almost the entire surface except for the center of the dielectric plate, and the low resistance conductor laid near the center of the dielectric plate is connected to the heating element of the resistance heater, The dielectric plate can be heated with good uniformity, and sputtering near the center of the dielectric plate can be prevented. In these devices, if a part or all of the coil has a multiple spiral shape, the inductance of the spiral coil becomes extremely small, so that a plasma processing device having excellent matching characteristics can be provided. Regarding the effect of multiple spiral coils, see T. Okumura and I.
Nakayama, “New inductively coupled plasmasource us
ing a multispiral coil ", Rev. Sci. Instrum. 66 (1
1), 1995.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a plasma processing method and apparatus according to various embodiments of the present invention will be described.
The structure other than the heating element 10 is the same as that of the conventional device shown in FIGS. Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a plan view of a heating element 10 constituting a resistance heater 9 used in the plasma processing apparatus according to the first embodiment of the present invention. As shown in FIG.
However, the current from the heater power supply 12 does not flow to the center 10a of the heating element 10 which is laid almost uniformly over substantially the entire surface including the center of the dielectric plate 5 and is arranged near the center of the dielectric plate 5. Is configured. That is, although a current flows through the heating element 10 as shown by an arrow in the figure,
The central portion 10a of the heating element 10 arranged near the center of the dielectric plate 5 has no open end, so that no current flows. Therefore, the central portion 10a of the heating element 10 does not generate heat near the center of the dielectric plate 5. Here, the heating element 1
The center portion 10a of 0 refers to a portion where there is no place for heat to escape, and the uniformity is maintained even with less heat generation than other portions (for example, a surrounding portion surrounding the center portion). In other words,
The central portion 10a is a portion for preventing the heat generating element 10 in the central portion from generating heat in order to improve the temperature uniformity of the dielectric plate 5 and to prevent the temperature in the central portion from rising excessively.

As an example, a diameter of 350 mm and a thickness of 25 m
m of the dielectric 5 made of quartz,
When a is 5% of the entire area of the dielectric 5 (the entire area of the surface of the dielectric 5 such as a circle or a rectangle facing the heating element 10), in the dielectric 5, the center 1 of the heating element 10
The portion corresponding to 0a is 210 ° C., and the outer peripheral end is 200 ° C. When the central portion 10a of the heating element 10 is 10% of the total area of the dielectric 5, the portion corresponding to the central portion 10a has a temperature of 200 ° C. and the outer peripheral end has a temperature of 200 ° C. Furthermore, when the central portion 10a of the heating element 10 is set to 20% of the total area of the dielectric 5, the portion corresponding to the central portion 10a is 190 ° C., and the outer peripheral end is 200 ° C. Therefore, as an example, it is preferable that 5 to 20% of the entire area of the dielectric 5 be the center 10 a of the heating element 10. Further, by using the heating element 10 shown in FIG. 1, the central portion 10a of the heating element 10 also acts as a Faraday shield near the center of the dielectric 5 to weaken the electrostatic coupling between the coil 6 and the plasma. Therefore, it is possible to prevent the vacuum side of the dielectric plate 5 from being largely negatively charged, and to prevent sputtering of the dielectric plate 5 due to high-speed collision of positive ions in the plasma toward the dielectric plate 5. . In the first embodiment, although not specifically shown, the central portion 10a of the heating element 10 is closed instead of being partially opened, and the width of the heater at the central portion 10a is changed. The resistance may be lowered by making the width sufficiently larger than the width of the portion, and the same effect as that of substantially opening may be obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a plan view of a heating element 10 and a low-resistance conductor 11 constituting a resistance heater 9 used in a plasma apparatus according to a second embodiment of the present invention. As shown in FIG. 2, the heating element 10 is different from the heating element 1 in the first embodiment in place of the central portion 10a opened.
The low-resistance conductor 1 having a resistance lower than that of the heating element 10 and made of, for example, copper
1 is provided. The heating element 10 itself is laid almost uniformly over almost the entire surface except for the vicinity of the center of the dielectric plate 5 and the low-resistance conductor 1 laid near the center of the dielectric plate 5.
1 is connected to the heating element 10. The current from the heater power supply 12 flows as indicated by the arrow in the figure, but the low-resistance conductor 11 is laid near the center of the dielectric plate 5. Does not generate heat. Note that the resistance of the low-resistance conductor 11 is such that when a current flows through the heating element 10 to generate heat, the low-resistance conductor 11 does not generate any heat even when a current flows through the low-resistance conductor 11, or the heat generated by the heating element 10. It is preferable to set the resistance so that heat generation can be almost ignored. The resistance of the low-resistance conductor is preferably, for example, 70% or less of the resistance of the heating element.

Measurements were made in order to confirm that the dielectric plate 5 was uniformly heated in the plasma processing apparatus having the above configuration, and it was found that heating with a very uniform temperature of 200 ° C. ± 5 ° C. was possible. . Further, by using the heating element 10 and the low-resistance conductor 11 shown in FIG. 2, the low-resistance conductor 11 also acts as a Faraday shield near the center of the dielectric 5, and electrostatically couples the coil 6 with the plasma. To prevent the vacuum side of the dielectric plate 5 from being greatly negatively charged, and to prevent sputtering of the dielectric plate 5 due to high-speed collision of positive ions in the plasma toward the dielectric plate 5. Can be.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a plan view of a heating element 10 and a low-resistance conductor 11 constituting a resistance heater 9 used in a plasma processing apparatus according to a third embodiment of the present invention. As shown in FIG. 3, the heating element 10 includes a low-resistance conductor 11 having a resistance lower than the resistance of the heating element 10 but having an open end at a location corresponding to the low-resistance conductor 11 of the second embodiment. It is provided. The heating element 10 itself is laid almost uniformly over almost the entire surface except for the central portion of the dielectric plate 5, and the low-resistance conductor 1 near the center of the dielectric plate 5 is provided.
1 is configured so that current from the heater power supply 12 does not flow. That is, a current flows through the heating element 10 as indicated by an arrow in the figure, and no current flows through the low-resistance conductive wire 11 near the center of the dielectric plate 5 because its tip is open. Therefore, near the center of the dielectric plate 5, the low-resistance conductor 1
1 does not generate heat.

Measurements were made to confirm that the dielectric plate 5 was uniformly heated in the plasma processing apparatus having the above configuration, and it was found that heating with a very uniform temperature of 200 ° C. ± 5 ° C. was possible. . Further, by using the heating element 10 and the low-resistance conductor 11 shown in FIG. 3, the low-resistance conductor 11 also acts as a Faraday shield near the center of the dielectric 5 and electrostatically couples the coil 6 with the plasma. To prevent the vacuum side of the dielectric plate 5 from being greatly negatively charged, and to prevent sputtering of the dielectric plate 5 due to high-speed collision of positive ions in the plasma toward the dielectric plate 5. Can be.

In the various embodiments of the present invention described above,
Although the case where the multiple planar spiral coils 6 are mounted along the dielectric plate 5 constituting the outer wall surface of the vacuum chamber 1 has been described, it goes without saying that the shape of the coils 6 and the The positional relationship between the dielectric plate 5 and the coil 6 is not limited to this, and includes other forms as shown in FIGS.
The present invention can be applied to various types of high frequency induction type plasma processing methods and apparatuses. That is, FIG. 4 shows that the coil 6 is constituted by a single planar spiral instead of a multiplex. FIG. 5 shows that the coil 6 is three-dimensionally shaped like a bell rather than a plane. In the coil 6 shown in FIG. 5, it is preferable that the curvature of the bell-shaped coil 6 is such that the height of the central portion is 20 to 30% of the outer diameter of the entire coil 6.

As is clear from the above description, according to the plasma processing method according to the embodiment of the present invention, the inside of the vacuum chamber 1 is evacuated while supplying the gas into the vacuum chamber 1, and the inside of the vacuum chamber 1 is evacuated. By supplying high frequency power to the coil 6 arranged along the dielectric plate 5 while controlling to a predetermined pressure,
In the plasma processing method for generating plasma in the vacuum chamber 1 and processing the substrate 8 mounted on the electrode 7 in the vacuum chamber 1, the dielectric plate 5 is heated by a heater 10 that generates heat except at the center. The substrate 8 is processed in a state in which plasma is generated in a state where the electrostatic coupling between the coil 6 and the plasma is weakened by the Faraday shield at the center, so that the dielectric plate 5 can be heated with good thermal uniformity, and Sputtering near the center of the dielectric plate 5 can be prevented. Also,
According to the plasma processing apparatus according to the embodiment of the present invention, the means 2 for supplying gas into the vacuum chamber 1, the means 3 for evacuating the vacuum chamber 1, and the substrate 8 placed in the vacuum chamber 1 7, a coil 6 for generating plasma in the vacuum chamber 1, a dielectric plate 5 on which the coil 6 is disposed, means 4 for supplying high-frequency power to the coil 6, and heating the dielectric plate 5 Heater 9 for heating and resistance heater 9
In the plasma processing apparatus provided with a heater power supply 12 for supplying a current to the heater, the heating element 1 of the resistance heater 9 is provided.
0 is laid almost uniformly over substantially the entire surface including the center of the dielectric plate 5 and the heating element 10 near the center of the dielectric plate 5
Is configured so that the current from the heater power supply 12 does not flow to the dielectric plate 5, so that the dielectric plate 5 can be heated with good uniformity.
Sputtering at the center of the dielectric plate 5 can be prevented.

Further, according to the plasma processing apparatus according to the above embodiment of the present invention, a means 2 for supplying gas into the vacuum chamber 1, a means 3 for evacuating the vacuum chamber 1, and a substrate in the vacuum chamber 1 An electrode 7 for mounting the coil 8, a coil 6 for generating plasma in the vacuum chamber 1, a dielectric plate 5 on which the coil 6 is arranged, and a means 4 for supplying high frequency power to the coil 6.
And a resistance heater 9 for heating the dielectric plate 5;
In a plasma processing apparatus provided with a heater power supply 12 for supplying a current to the resistance heater 9, the heating element 10 of the resistance heater 9 is laid almost uniformly over almost the entire surface of the dielectric plate 5 except for the vicinity of the center thereof. Since the low resistance wire 11 laid near the center of the plate 5 is connected to the heating element 10 of the resistance heater 9, the dielectric plate 5 can be heated with good uniformity, and sputtering near the center of the dielectric plate 5 can be performed. Can be prevented. If a part or the whole of the coil 6 has a multiple spiral shape, the inductance of the spiral coil becomes extremely small, so that a plasma processing apparatus having excellent matching characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view of a heating element constituting a resistance heater used in a first embodiment of the present invention.

FIG. 2 is a plan view of a heating element and a low-resistance conductor constituting a resistance heater used in a second embodiment of the present invention.

FIG. 3 is a plan view of a heating element and a low-resistance conductor constituting a resistance heater used in a third embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a plasma processing apparatus used in another embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a plasma processing apparatus used in still another embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a configuration of a plasma processing apparatus used in an embodiment of the present invention and a conventional example.

FIG. 7 is a plan view of a coil used in an embodiment of the present invention and a conventional example.

FIG. 8 is a plan view of a heating element constituting a resistance heater used in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Gas supply unit 3 Pump 4 High frequency power supply for coil 5 Dielectric plate 6 Coil 7 Electrode 8 Substrate 9 Resistance heater 10 Heating element 10a Heating element center part 12 Heater power supply 13 High frequency power supply for electrode

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/3065 C23C 16/50 C23F 4/00 H01L 21/205 H05H 1/46

Claims (6)

(57) [Claims] A coil (6) disposed along a dielectric plate (5) while evacuating the vacuum chamber while supplying gas into the vacuum chamber (1) and controlling the vacuum chamber to a predetermined pressure. )
A plasma processing method for generating plasma in the vacuum chamber by supplying high-frequency power to the substrate to process a substrate (8) mounted on an electrode (7) in the vacuum chamber; The center (5-10%)
Plasma is generated in a state in which the dielectric plate is heated by a heater (9) that generates heat other than a, 11), and the Faraday shield at the center reduces the electrostatic coupling between the coil and the plasma. In the state
A plasma processing method comprising processing the substrate. 2. The plasma processing method according to claim 1, wherein high-frequency power is supplied to said electrodes. 3. A means (2) for supplying gas into the vacuum chamber (1), a means (3) for evacuating the vacuum chamber, and an electrode (10) for mounting a substrate (8) in the vacuum chamber. 7)
A coil (6) for generating plasma in the vacuum chamber, a dielectric plate (5) on which the coil is disposed, a unit (4) for supplying high-frequency power to the coil, and a resistor for heating the dielectric plate A heater (9) and a heater power supply (1) for supplying a current to the resistance heater.
2) wherein the heating element (10) of the resistance heater is laid almost evenly over substantially the whole surface including the vicinity of the center, which is 5 to 20% of the total area of the dielectric plate, and A plasma processing apparatus characterized in that current from the heater power supply does not flow through the heating element (10a) near the center of the dielectric plate. 4. A means (2) for supplying gas into the vacuum chamber (1), a means (3) for evacuating the vacuum chamber, and an electrode (10) for mounting a substrate (8) in the vacuum chamber. 7)
A coil (6) for generating plasma in the vacuum chamber, a dielectric plate (5) on which the coil is disposed, a unit (4) for supplying high-frequency power to the coil, and a resistor for heating the dielectric plate A heater (9) and a heater power supply (1) for supplying a current to the resistance heater.
2) wherein the heating element (10) of the resistance heater is laid almost evenly over almost the entire surface except for the vicinity of the center, which is 5 to 20% of the total area of the dielectric plate, and A plasma processing apparatus, characterized in that a low-resistance wire (11) laid near the center of the dielectric plate is connected to the heating element of the resistance heater. 5. The plasma processing apparatus according to claim 3, further comprising means (13) for supplying high-frequency power to said electrodes. 6. The plasma processing apparatus according to claim 3, wherein a part or the whole of the coil has a multiple spiral shape.