JP3540133B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plasma processing apparatus and a plasma processing method , and more particularly to a plasma processing apparatus and a plasma processing method for performing film formation and etching processing using plasma.
The plasma processing apparatus is configured to perform film formation and etching on a semiconductor to be processed in a continuous process using plasma. According to this plasma processing apparatus, film formation and etching with good reproducibility can be performed by always generating the same plasma and performing the same processing.
[0002]
However, if dirt adheres to the chamber where the processing is performed, the state of generation of plasma changes, and there is a possibility that film formation and etching processing with good reproducibility cannot be performed. Therefore, there is a demand for a plasma processing apparatus capable of suppressing generation of dirt in the chamber.
[0003]
[Prior art]
In general, when a film is formed on a wafer in a semiconductor process or when a film on a wafer is etched, processing is often performed using plasma.
As a plasma processing apparatus used for film formation and etching, a parallel plate type, an ECR type, a helicon type, an ICP (inductive coupling) type and the like are mainly known. Helicon type and ICP (inductive coupling) type are increasingly used. In particular, the ICP (inductive coupling) type has a relatively compact structure and is widely used.
[0004]
FIG. 5 is a schematic view showing a conventional ICP (inductively coupled) plasma processing apparatus 10 (hereinafter simply referred to as a plasma processing apparatus) used for etching. FIG. 6 is an enlarged view of the vicinity of an antenna 14 of the plasma processing apparatus. FIG. As shown in each of the drawings, the plasma processing apparatus 10 generally includes a quartz chamber 12, an antenna 14, matching circuits 16 and 18, a high-frequency power supply 20, a wafer bias power supply 22, and the like.
[0005]
The quartz chamber 12 is filled with an etching gas, and a coil-shaped antenna 14 is wound therearound. This antenna 14 is connected to a high-frequency power supply 20 via a matching circuit 16. Specifically, as shown in FIG. 6, the high-frequency power supply 20 (matching circuit 16) and the antenna 14 are connected by two wires 32 and 34, and one wire 34 is grounded. Therefore, the wiring 32 functions as a power supply line, and the wiring 34 functions as a ground line.
[0006]
Then, high-frequency power (power for generating plasma; hereinafter, referred to as source power) is supplied to the antenna 14 from the high-frequency power supply 20 to generate plasma 30 (see FIG. 6) in the quartz chamber 12. Have been.
The wafer (semiconductor) 24 is mounted on a stage 26 provided in the quartz chamber 12, and is connected to a wafer bias power supply 22 via a blocking capacitor 28 and a matching circuit 18 in an AC manner. The wafer bias applied to the stage 26 by the wafer bias power supply 22 is important for obtaining a high etching rate and anisotropy in etching.
[0007]
That is, by applying a wafer bias, ions generated by the plasma can be drawn vertically into the wafer, thereby achieving anisotropic etching, and the etching rate, underlayer, and The selection ratio with respect to the mask material can be set (the power of the wafer bias power supply 22 is hereinafter referred to as bias power).
[0008]
The wafer processing using plasma is always performed by using the above-described plasma processing apparatus 10 and setting the etching gas flow rate, the chamber internal pressure, the stage position, the source power, the bias power, and the like to be equal for each processing wafer. The etching rate and the selectivity between the underlayer and the mask material are obtained.
[0009]
[Problems to be solved by the invention]
Here, the operation principle of the inductively coupled plasma device 10 will be described with reference to FIGS. FIG. 6 is an enlarged view of a main part of the vicinity of the antenna 14 of the plasma device 10, and FIG. 7 shows an equivalent circuit of the generated inductively coupled plasma. As shown in FIG. 6, the plasma 30 is generated by supplying source power from the high frequency power supply 20 to the antenna 14 wound around the quartz chamber 12. At this time, when a high-frequency current flows through the antenna 14, a high-frequency magnetic field is generated to generate an induced electric field, and the induced electric field drives electrons to generate and maintain plasma. In the mechanism in which electrons are driven by the induced electric field, as shown in FIG. 7, the antenna 14 corresponds to a primary coil of a transformer, and the plasma 30 corresponds to a secondary coil.
[0010]
Next, a case where the quartz chamber 12 is contaminated in the plasma processing apparatus 10 having the above configuration will be considered. When the quartz chamber 12 is contaminated, even if the same high-frequency magnetic field is generated from the antenna 14, the magnetic field that the plasma 30 feels from the antenna 14 is weakened, and the electric field applied to the plasma 30 is reduced even with the same source power. In such a state, the plasma processing apparatus 10 must be temporarily stopped and the quartz chamber 12 must be cleaned.
[0011]
Dirt adhering to the quartz chamber 12 becomes more severe as the number of processed wafers 24 increases, and thus requires periodic cleaning. In addition, chamber cleaning requires more than half a day, during which time the plasma processing apparatus 10 must be stopped.
Causes of contamination of the quartz chamber 12 include a material to be etched, an etched (sputtered) mask material, a redeposition of an etched (sputtered) base material, deposition of radicals generated by the plasma 30, and the like. If the quartz chamber 12 is contaminated by these factors, in the case of a device that turns on the power supply from outside the quartz chamber 12 to generate the plasma 30 such as the inductively coupled plasma processing apparatus 10, the contamination of the power supply is hindered and the same plasma is used. It is difficult to generate 30 continuously.
[0012]
In particular, if the stain is due to a conductive substance, the power consumption due to the stain increases, and the variation in the etching rate and the selectivity between the base and the mask material increases. Therefore, if dirt adheres to the quartz chamber 12, the state of generation of plasma changes over time, which causes a problem that film formation and etching with good reproducibility cannot be performed.
[0013]
Conventionally, however, no means has been provided for suppressing contamination that adheres to the quartz chamber 12, so that the quartz chamber 12 needs to be frequently cleaned, and thus the shutdown period of the plasma processing apparatus 10 becomes longer, and the efficiency is reduced. There is a problem that it is not possible to perform a film forming process or an etching process.
The present invention has been made in view of the above points, and an object of the present invention is to provide a plasma processing apparatus and a plasma processing method that can lengthen a cleaning cycle of a chamber.
[0014]
[Means for Solving the Problems]
The above problem can be solved by taking the following measures.
In the invention according to claim 1,
Has an inductive coupling type antenna in the chamber, the plasma processing apparatus Ru plasma is generated into the chamber by supplying power to the antenna,
Those characterized both ends of the coil forming the antenna, between the high frequency power supply for supplying power to the coil, in that a switching means for changing put the power supply wiring and ground wiring connected to the coil ends It is.
[0015]
In the invention according to claim 2,
In a plasma processing method of supplying power to an inductively coupled antenna installed in a chamber to generate plasma in the chamber,
A step of connecting a power supply wiring to one end of the coil forming the antenna, connecting a ground wiring to the other end, and generating plasma;
Generating a plasma by exchanging the power supply wiring and the ground wiring connected to both ends of the coil .
[0017]
Each means described above operates as follows.
According to the invention described in claims 1 and 2 ,
By supplying power to an inductively-coupled antenna provided in a chamber to generate plasma in the chamber, a semiconductor can be subjected to film formation processing or etching processing. Further, the both ends of the coil forming the antenna, between the high frequency power supply for supplying power to the coil, by providing the switching means for changing put the power supply wiring and ground wiring connected to the coil ends, the dirt chamber Adhesion can be suppressed. Hereinafter, the reason will be described.
[0018]
The inventor paid attention to a position where dirt adheres to the chamber in the etching process and the sputtering process using the above-described plasma processing apparatus having the conventional configuration.
As a result, it has been found that a position where a large amount of dirt adheres to the chamber basically occurs in the vicinity where the antenna is connected to the ground. On the other hand, it has been found that it is unlikely to occur in the vicinity of the power supply section to which the high frequency power of the antenna is supplied.
[0019]
This is presumed to be due to the fact that a spattering action occurs near the supply of the high-frequency power, so that dirt hardly adheres to the chamber.
Therefore, in a configuration in which both ends of the coil are not electrically switched as in the related art, a dirt is continuously accumulated in the chamber near the ground connected to the antenna, and conversely, the power supply unit to which the high frequency power of the antenna is supplied In the vicinity, dirt does not always adhere to the chamber.
[0020]
In contrast, as in the present invention, between the high frequency power supply for supplying power to both ends and the coil of the coil forming the antenna, providing a switching means for changing put the power supply wiring and ground wiring connected to the coil ends Thus, the above-described sputtering action can be generated at each of both ends of the coil by the switching process.
Accordingly, it is possible to prevent dirt from being intensively deposited on one of both ends of the coil, and to prevent dirt from adhering to the inside of the chamber. Accordingly, the cleaning cycle of the chamber can be lengthened, and the time for stopping the plasma processing apparatus for the cleaning processing can be shortened, so that efficient plasma processing can be performed.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
1 to 3 are views showing one embodiment of a plasma processing apparatus according to the present invention. FIG. 1 is a configuration diagram of the plasma processing apparatus 40, and FIGS. 2 and 3 are enlarged configuration views showing the vicinity of the antenna 44 of the plasma processing apparatus 40. As shown in each of the drawings, the plasma processing apparatus 40 generally includes a quartz chamber 42, an antenna 44, matching circuits 46 and 48, a high-frequency power supply 40, a wafer bias power supply 42, and a switching circuit 70 which is a main part of the present invention. It consists of.
[0024]
The quartz chamber 42 is filled with an etching gas, and a coil-shaped antenna 44 is wound therearound. The antenna 44 is connected to a high frequency power supply 50 via a matching circuit 46 and a switching circuit 70.
Specifically, as shown in FIGS. 2 and 3, the high-frequency power supply 50 (matching circuit 46) and the antenna 44 are connected by two wires 52 and 54, and one wire 54 is grounded. . Therefore, the wiring 52 functions as a power supply line that supplies power from the high-frequency power supply 50 to the antenna 44 (hereinafter, the wiring 52 is referred to as a power supply wiring), and the wiring 54 functions as a ground line (hereinafter, the wiring 54 is a ground wiring). Described). The two wires 52 and 54 are connected to connection terminals 66 and 68 of the antenna 44.
[0025]
In the above configuration, when high-frequency power (power for generating plasma; hereinafter, referred to as source power) is supplied from the high-frequency power supply 50 to the antenna 44, plasma 60 (see FIGS. 2 and 3) is generated in the quartz chamber. . At this time, the frequency adjustment (matching) of the applied power is performed by the matching circuit 46 according to the state (for example, gas concentration or the like) in the quartz chamber 42. The matching process is performed by controlling the matching circuit 46 by the control device 72 which controls the plasma processing device 40 in an integrated manner.
[0026]
A wafer (semiconductor) 54 which is a workpiece (that is, an object on which a film forming process or an etching process is performed) is mounted on a stage 56 provided in the quartz chamber 42. This stage 56 is AC-connected to the wafer bias power supply 52 via a blocking capacitor 58 and a matching circuit 48. The wafer bias applied to the stage 56 by the wafer bias power supply 52 is important for obtaining a high etching rate and anisotropy in etching.
[0027]
That is, by applying a wafer bias, ions generated by the plasma 60 can be drawn vertically into the wafer 54, thereby achieving etching anisotropy. , And a selection ratio with respect to the mask material (the power of the wafer bias power supply 22 is hereinafter referred to as bias power).
[0028]
The matching circuit 48 adjusts the frequency (matching) of the wafer bias according to the state (for example, gas concentration or the like) in the quartz chamber 42. This matching process is performed by the control device 72 controlling the matching circuit 48.
On the other hand, the switching circuit 70 is constituted by a relay device as shown in FIGS. 2 and 3, for example. The switching circuit 70 is configured to have a pair of movable contacts 74 and 76 and four fixed contacts 78a, 78b, 80a and 80b therein.
[0029]
Of the pair of movable contacts 74, 76, the movable contact 74 is connected to the power supply wiring 62, and the movable contact 76 is connected to the ground wiring 64. Further, among the four fixed contacts 78a, 78b, 80a, 80b, the fixed contacts 78a, 78b are integrally connected on the way and then connected to the connection terminal 66 of the antenna 44.
Further, among the fixed contacts 78a, 78b, 80a, 80b, the fixed contacts 78a, 78b are connected integrally to the connection terminal 66 of the antenna 44 after being integrally connected on the way. Further, the fixed contacts 80a and 80b are also integrally connected on the way and then connected to the connection terminal 68 of the antenna 44.
[0030]
In the above configuration, the pair of movable contacts 74 and 76 disposed in the switching circuit 70 are configured to be integrally movable by a driving device (not shown) controlled by the control device 72. Specifically, the switching circuit 70 includes a first state in which the pair of movable contacts 74 and 76 shown in FIG. 2 are connected to the fixed contacts 78a and 78b, and a pair of movable contacts 74 and 76 shown in FIG. Switching between the second state connected to 80a and 80b.
[0031]
Accordingly, in the first state shown in FIG. 2, the power supply wiring 62 is connected to the connection terminal 66 of the antenna 44 via the movable contact 74 and the fixed contact 78a, and the ground wiring 64 is connected via the movable contact 76 and the fixed contact 80a. It is connected to the connection terminal 68 of the antenna 44. That is, power is supplied to the connection terminal 66 of the antenna 44 located at the upper part in the figure, and the connection terminal 68 located at the lower part is grounded.
[0032]
On the other hand, in the second state shown in FIG. 3, the power supply wiring 62 is connected to the connection terminal 68 of the antenna 44 via the movable contact 74 and the fixed contact 80b, and the ground wiring 64 is connected via the movable contact 76 and the fixed contact 78b. Connected to connection terminal 66 of antenna 44. That is, the connection terminal 66 of the antenna 44 located at the upper part in the figure is grounded, and power is supplied to the connection terminal 68 located at the lower part.
[0033]
As described above, the switching circuit 70 is disposed between the connection terminals 66 and 68 at both ends of the coil forming the antenna 44 and the matching circuit 46 for matching the antenna 44, and electrically connects the connection terminals 66 and 68. Provides a function to switch.
Next, the operation and action of the plasma processing apparatus 40 having the above configuration will be described.
[0034]
First, attention is paid to the first state shown in FIG. In the first state, power is supplied to the connection terminal 66 of the antenna 44 located at the upper part in the figure, and the connection terminal 68 located at the lower part is grounded. As described above, in the quartz chamber 42, the position where a large amount of dirt adheres is basically near the ground connected to the antenna 44, that is, near the connection terminal 68 (in the figure, the dirt is denoted by reference numeral 82). Shown).
[0035]
On the other hand, dirt hardly adheres to the vicinity of the power supply unit to which the high-frequency power of the antenna 44 is supplied, that is, the position near the connection terminal 66. This is presumed to be due to the fact that a spattering action occurs near the supply of the high-frequency power, so that dirt hardly adheres to the chamber.
The conventional plasma processing apparatus 10 described with reference to FIGS. 5 and 6 has a configuration that can realize only this first state. Therefore, in the vicinity where the antenna is connected to the ground, dirt is constantly accumulated in the chamber, so that the cleaning cycle has to be accelerated.
[0036]
However, by providing the switching circuit 70 for electrically switching both ends of the coil as in the present invention, the state of the plasma processing apparatus 40 is changed from the first state shown in FIG. 2 to the second state shown in FIG. Can be.
In the second state, power is supplied to the connection terminal 68 of the antenna 44 located at the lower part in the figure, and the connection terminal 66 located at the upper part is grounded. As described above, dirt 82 is deposited near the connection terminal 68 in the first state. However, the dirt 82 near the connection terminal 68 is scattered and removed by the sputter action generated by supplying the high frequency power to the connection terminal 68. Conversely, dirt 84 is newly generated near the grounded connection terminal 66.
[0037]
Therefore, by alternately switching the electrical polarities (characteristics) of the connection terminals 66 and 68 by the switching circuit 70, the above-described sputtering action can be generated at each of the connection terminals 66 and 68. Accordingly, it is possible to prevent the dirt 82, 84 from being intensively deposited on one of the vicinity of the arrangement position of the connection terminals 66, 68, and to suppress the adhesion of the dirt on the entire inside of the quartz chamber 42. .
[0038]
As described above, since it is possible to suppress the attachment of dirt in the quartz chamber 42, it is possible to lengthen the cleaning cycle of the quartz chamber 42 and shorten the time for stopping the plasma processing apparatus 40 for the cleaning process. Therefore, efficient plasma processing can be performed.
The timing of the switching by the switching circuit 70 is not particularly limited, and the material (etching material, mask material, base material, etc.) provided in the quartz chamber 42 at the time of processing, or processing. It can be set arbitrarily based on the state and the like. For example, the connection terminals 66 and 68 may be electrically switched each time the switching device 70 processes one wafer 54, or the connection terminals 66 and 68 may be performed a plurality of times during the processing of one wafer 54. May be electrically switched. As described above, by performing the switching process relatively frequently, it is possible to reliably prevent the quartz chamber 42 from being contaminated.
[0039]
When the plasma processing apparatus 40 is used in the etching (including sputter etching) process, at least one of the material to be etched and the mask material is Pt, Ir, Ru, RuO, and Cu having a low vapor pressure. It is known that these conductive films easily adhere to the quartz chamber 42. Since the conductive dirt has a great effect on the plasma 60, it has a great effect on the selectivity between the etching grate, the mask and the material of the base.
[0040]
However, since the plasma processing apparatus 40 effectively suppresses the contamination of the quartz chamber 42 as described above, the material to be etched, the mask material, or the base material is made of platinum (Pt) having conductivity. ), Iridium (Ir), ruthenium (Ru), ruthenium oxide (RuO), copper (Cu), or the like, the cleaning cycle of the quartz chamber 42 can be made much longer than in the past.
[0041]
Next, experimental results of experiments performed by the present inventors to demonstrate the effects of the present invention will be described. In this experiment, the conventional plasma processing apparatus 10 and the plasma processing apparatus 40 according to the present invention were used to perform an etching process on each of the apparatuses 10 and 40 under substantially the same conditions, and the resulting dirt was evaluated.
(Comparative example)
In the conventional plasma processing apparatus 10, Pt etching of the resist mask was performed under the following conditions: Ar: 50 cc / min, Cl ₂ : 75 cc / min, pressure: 5 mTorr, source power: 1000 W, and bias power: 1000 W.
[0042]
FIG. 8 shows the etching rate of Pt and the ratio (selectivity) of the etching rate of Pt to the resist with respect to the number of processed wafers at this time. As shown in the figure, it can be seen that the etching rate and the selectivity of Pt change every time the number of processed wafers is increased. 〔Example〕
On the other hand, in the plasma processing apparatus 40 according to the present invention shown in FIGS. 1 to 3, Ar: 50 cc / min, Cl ₂ : 75 cc / min, pressure: 5 mTorr, source power: 1000 W, bias power: 1000 W, constant Under the conditions described above, Pt etching of the resist mask was performed. Both ends of the antenna 44 are electrically exchanged for each wafer.
[0043]
FIG. 4 shows the etching rate of Pt and the ratio (selection ratio) of the etching rate of Pt to the resist with respect to the number of processed wafers at this time. As shown in the figure, the change in the etching rate and the selectivity of Pt is smaller than that of the conventional characteristic shown in FIG. Naturally, if there is a case where the chamber is contaminated by processing one wafer, it is effective to replace both ends of the coil during the processing of the wafer.
[0044]
【The invention's effect】
As described above, according to the present invention, the above-described sputtering action can be generated at each of both ends of the coil by the switching process, so that it is possible to prevent the accumulation of dirt on one of the two ends of the coil, and to prevent the inside of the chamber from being contaminated. Can be prevented from adhering to the surface. Accordingly, the cleaning cycle of the chamber can be lengthened, and the time for stopping the plasma processing apparatus for the cleaning processing can be shortened, so that efficient plasma processing can be performed.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a plasma processing apparatus according to one embodiment of the present invention.
FIG. 2 is a main part configuration diagram showing a first switching state of the plasma processing apparatus according to one embodiment of the present invention;
FIG. 3 is a main part configuration diagram showing a second switching state of the plasma processing apparatus according to one embodiment of the present invention;
FIG. 4 is a diagram for explaining the effect of the present invention, and is a diagram showing a Pt etching rate and a Pt / resist selection ratio with respect to the number of processed wafers.
FIG. 5 is a configuration diagram showing a conventional ICP (inductive coupling) type plasma processing apparatus.
FIG. 6 is a configuration diagram of a main part of a plasma processing apparatus as an example of the related art.
FIG. 7 is a diagram showing an equivalent circuit of an inductively coupled plasma.
FIG. 8 is a diagram showing a Pt etching rate and a Pt / resist select ratio with respect to the number of processed wafers in a conventional plasma processing apparatus.
[Explanation of symbols]
Reference Signs List 40 Plasma processing device 42 Quartz chamber 44 Antenna 50 High frequency power supply 52 Wafer bias power supply 54 Wafer 56 Stage 60 Plasma 62, 64 Wiring 66, 68 Connection terminal 70 Switching circuit 72 Controller

Claims (2)

In a plasma processing apparatus having an inductively coupled antenna in a chamber and supplying power to the antenna to generate plasma in the chamber,
And both ends of the coil forming the antenna, between the high frequency power supply for supplying power to the coil, plasma, characterized in that a switching means for changing put the power supply wiring and ground wiring connected to the coil ends Processing equipment.   In a plasma processing method of supplying power to an inductively coupled antenna installed in a chamber to generate plasma in the chamber,
  A step of connecting a power supply wiring to one end of the coil forming the antenna, connecting a ground wiring to the other end, and generating plasma;
  Generating a plasma by exchanging the power supply wiring and the ground wiring connected to both ends of the coil.

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