JP2003115400A - Plasma processing equipment of large area wafer processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the plasma processing equipment of a large area wafer processing which can control plasma density and uniformity. SOLUTION: The plasma processing equipment is used for the large area wafer processing. This plasma processing equipment has a doubly concentric rf electrode as an upper electrode. The doubly concentric rf electrode is used for generation of the plasma by the capacitive coupling-mechanism or the capacitive and the inductive coupling mechanism. It has a central rf electrode and an outside rf electrode of the doubly concentric rf electrode. The central rf electrode has a circular shape and the outside rf electrode is arranged around the central rf electrode. A dielectric component is arranged between the center and outside rf electrodes. Two rf generators are connected to the center and outside rf electrodes via a matching circuit and an rf filter, respectively. A 3rd flat plate rf electrode as an wafer holder is arranged at a bottom side surface parallel to the doubly concentric rf electrode. The sidewall of a reaction container is electrically grounded as a 4th electrode.

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 for large area wafer processing, and more particularly to a large area plasma source having a controlled radial distribution profile for plasma density in a desired plane. This plane is set between the double concentric rf electrode and the bottom electrode and the generated plasma is useful for plasma assisted etching, chemical vapor deposition, and sputter deposition applications. These applications are used in the microelectronics industry to fabricate semiconductor devices on Si (silicon) substrates or other substrates.

[0002]

2. Description of the Related Art In the last decade, semiconductor device manufacturers have increased the standard diameter of silicon wafers used to manufacture integrated circuits from 100 mm to 300 mm. The microelectronics industry expects the next standard diameter to be approximately 450 mm. With the increasing diameter of silicon wafers, large area plasma sources are required to process these wafers. Control of plasma parameters such as plasma density, plasma potential, plasma uniformity, and radial densities of ions and neutrals at the plane of the wafer, even if it is not technically difficult to fabricate larger area plasma sources. very hard. In particular,
Higher radial plasma uniformity at the wafer surface is important for most wafer processing. In most conventional plasma sources, the controllability of radial plasma uniformity is limited, especially when increasing size for large area wafer processing. This is explained in detail using a conventional parallel plate capacitively coupled plasma device.

A schematic diagram of a conventional parallel plate capacitively coupled plasma device is shown in FIG. This plasma device has two parallel electrodes called an upper electrode 101 and a lower electrode 102,
It is composed of a cylindrical side wall 104, a plurality of gas inlets 110 above the upper electrode 101, and an exhaust port 108. The upper electrode 101 has an rf (high frequency) generator 115.
Is supplied with a rf current that typically operates at a frequency of 13.56 MHz via a matching circuit 114. The lower electrode 102 may or may not be supplied with the rf current. In the structure shown in FIG. 10, the matching circuit 1
It has an rf generator 113 connected to the lower electrode 102 via 12.

The upper electrode 101 is a ring-shaped upper plate 1
It is supported by the dielectric member 103 fixed to 04a. The upper electrode 101 has a gas reservoir 109 inside and a gas inlet 110 on its lower surface. The main gas introduction pipe 111 is connected to the upper electrode 101. Similarly, the bottom electrode 102 also includes a bottom plate 106.
It is supported by a dielectric member 105 fixed to.

[0005]

The plasma is the upper electrode 1
01 produced by capacitive coupling of the rf power applied to. The change in plasma density in the radial direction below the upper electrode 101 is shown in FIG. Since the upper electrode 101 has a flat plate shape, the plasma density in the vicinity of the upper electrode 101 exhibits higher radial uniformity. This is indicated by the curve labeled 116. This plasma then diffuses toward the cylindrical sidewall 104 and extinguishes at its surface. Therefore, the plasma density and the radial uniformity of the plasma decrease towards the lower electrode 102. The radial uniformity of the plasma in the plane near the surface of the wafer mounted on the bottom electrode 102 is shown by the curve labeled 117. This change in plasma density is typically common to most conventional parallel plate capacitively coupled plasma sources.

There are two ways in which the reduction in radial uniformity of the plasma at the substrate surface can be reduced. The first method is to increase the diameter of the upper electrode by keeping the gap between the upper electrode and the lower electrode constant. This causes the diameter of the reaction vessel and the volume of the reaction vessel to increase. Therefore, higher rf power is required to obtain the same plasma density and processing speed. The second method is to reduce the operating pressure to facilitate fast diffusion of the plasma. However, the reduction in pressure results in a reduction in plasma density and therefore the rf power must be increased to maintain the same processing rate.

At higher rf powers, the plasma density saturates, even though increasing rf power results in an increase in plasma density. After this rf power, increasing rf power does not result in increasing plasma density.
On the contrary, the added rf power causes excessive heating of the rf electrode and the devices around it, which require strict cooling conditions.

Therefore, it is somewhat difficult to control the density and uniformity of plasma, especially on large area wafers, using conventional parallel plate capacitively coupled plasma equipment.

It is an object of the present invention to provide a plasma processing apparatus for processing a large area wafer capable of controlling plasma density and uniformity.

[0010]

The plasma processing apparatus of the present invention is configured as follows in order to solve the above problems.

The plasma processing apparatus for large area wafer processing according to the present invention has double concentric rf electrodes. This double concentric rf electrode is used to generate the plasma by a capacitive coupling mechanism or a capacitive and inductive coupling mechanism. The central rf electrode of the double concentric rf electrode has a circular shape or a shape close to a circular shape, and the outer rf electrode thereof is arranged around the central rf electrode. A dielectric member is disposed between the center and outer rf electrodes. The two rf generators are respectively connected to the central and outer rf electrodes via a matching circuit and an rf filter. A third flat plate rf electrode as a wafer holder is arranged on a lower plane parallel to the double concentric rf electrode. The side wall of the reaction container is electrically grounded as a fourth electrode.

A new reactor configuration was invented with four electrodes, in which the upper electrode was constituted by a double concentric rf electrode, which produced two independently controllable plasmas. , These two plasmas diffuse and make one plasma.

In the above plasma processing apparatus for large area wafer processing, the outer rf electrode has a large flat surface facing the plasma for generating the plasma by a capacitive coupling mechanism.

In the above plasma processing apparatus for large area wafer processing, a single loop antenna is used instead of the outer rf electrode to generate plasma by an inductive coupling mechanism.

In the above plasma processing apparatus for processing a large area wafer, the central and outer rf surfaces facing the plasma are exposed.
The lower surface of either one of the electrodes or the lower surface of both rf electrodes is covered with a dielectric member or a semiconductor member.

In the above plasma processing apparatus for large area wafer processing, one or both of the central and outer rf electrodes have a gas reservoir and a plurality of gas inlets for introducing a process gas into the reaction chamber. ing.

In the above plasma processing apparatus for large area wafer processing, one or both of the central and outer rf electrodes are provided with a mechanism for controlling their surface temperature.

In the above-mentioned plasma processing apparatus for processing a large area wafer, the double concentric rf electrodes are 1 to 100 MH.
Same rf frequency in the range of z or two different rf
Two separate rf currents are supplied by two different rf generators operating at frequency.

In the above plasma processing apparatus for processing a large area wafer, each of the center and outer rf electrodes is r.
The rf current and the negatively biased DC voltage are supplied from the f generator and the DC voltage supply, respectively.
The rf generator connected to one electrode and the DC voltage supply are independent of those connected to the other rf electrode.

In the above plasma processing apparatus for large area wafer processing, each rf electrode of the double concentric rf electrodes is connected to the corresponding rf generator via a matching circuit and a phase shifter.

[0021]

Preferred embodiments will be described below with reference to the accompanying drawings. The details of the present invention will be made clear through the description of the embodiments.

A first embodiment of the present invention will be described with reference to FIG. 1, which shows a cross-sectional view of a plasma processing apparatus. This device has double concentric rf (high frequency) electrodes 1 and 2, a lower electrode 3,
It has a reaction vessel with a cylindrical side wall 4, a plurality of gas inlets 5 and one exhaust port 6. All electrodes are made of metal, eg aluminum. Typically,
The double concentric rf electrodes 1 and 2 have a circular shape. In particular, the outer rf electrode has a circular ring shape. However, the shape of the electrodes may be square, pentagonal, hexagonal or any similar shape. These rf
The dimensions of the electrodes 1, 2 are not important. If the double concentric electrodes 1 and 2 are circular, the plasma device is 300m
If it is intended for the processing of m-diameter wafers, the diameter of the central electrode 1 is in the range of 200 mm to 300 mm. The outer shape of the outer rf electrode 2 is 200 mm to 500 mm
Is in the range. If these rf electrodes 1 and the other electrodes are of different shapes, comparable dimensions are used. The inner and outer rf electrodes (1, 2) are separated by an inner dielectric ring 7. The material of the dielectric ring 7 is not critical and it is chosen depending on other requirements such as electrode temperature. The width of the narrowest part of the dielectric ring 7 is not critical and can vary from 1 mm to about 20 mm. The outer rf electrode is also placed on the outer dielectric ring 8 to electrically insulate it from the grounded surface. The thickness and the dielectric constant of the dielectric ring 8 are not important.

The process gas is initially rf at the center and outside rf.
It is introduced via the gas reservoirs 9, 12 in the electrodes (1, 2) and the main gas pipes 11, 12. This gas then moves to the reaction vessel through a plurality of gas inlets 5 made in the central and outer rf electrodes (1, 2). Even if the process gas is supplied through both the central and outer rf electrodes (1,2) as shown in FIG. 1 and described above, only one process gas is supplied.
It is also possible to supply only through the f electrode, for example the central rf electrode 1. Furthermore, the flow rates of the process gases introduced via the central and outer rf electrodes are not always the same and can be different. Furthermore, the process gas or gas mixture introduced through the central and outer rf electrodes can be different.

Both the central and the outer rf electrodes (1, 2) have a temperature control mechanism. For this purpose, a channel 39 is created through the rf electrodes 1 and 2. In the flow channel 39, the temperature control liquid flows. The temperatures of the central and outer rf electrodes can be independently controlled by separately dividing the channels 39 of the central and outer rf electrodes 1 and 2 and connecting them to two different temperature controllers. In FIG. 1, 40 indicates a temperature control liquid inlet, and 41 indicates a temperature control liquid outlet.

The central and outer rf electrodes (1, 2) are respectively connected to two different rf generators 13, 14 operating at two different frequencies or at the same frequency.
As shown in FIG. 1, both rf generators 13, 14 are located outside the top cover 24 of the reaction vessel. r
The f generator 13 is coupled to the central rf electrode 1 via the rf matching circuit 15 and the rf filter 17. The rf generator 14 is coupled to the outer rf electrode 2 via a matching circuit 16 and an rf filter 18. Usually, the rf current is applied to the center of the central rf electrode 1 in order to maintain symmetrical rf current flow. However, the rf current is
Above, it is difficult to obtain a symmetrical rf current flow on the outer rf electrode 2, so it may be applied at any place.

The frequency of the rf current in either rf generator is not critical, it is 1-100 MHz.
Can be changed within the range. The rf currents applied to the electrodes 1 and 2 are usually different from each other.
For example, an rf current of 60 MHz is applied to the central rf electrode 1, while 13.56 M is applied to the outer rf electrode.
An rf current of Hz is provided. It is appropriate to provide a high frequency rf current (eg 60 MHz) to the central rf electrode 1 and a low frequency rf current (eg 13.56 MHz) to the outer rf electrode 2. This is because the plasma density tends to be generated asymmetrically when an rf current of high frequency, for example 60 MHz, is applied asymmetrically to a particularly large area electrode.
Only the central rf electrode 1 gives a symmetrical flow of rf current to its surface, so that the high frequency rf current will be transmitted to the central rf electrode 1.
Should be given to. On the other hand, when the frequency of the rf current is low, for example, 13.56 MHz, even the flow of the asymmetric rf current on the surface of the rf electrode does not cause the generation of asymmetric plasma. Therefore, a low frequency rf current should be applied to the outer rf electrode 2, which gives an asymmetric rf current flow on its surface.

Rf given to the central and outer electrodes 1 and 2
The currents are matched boxes 15, 16 and rf filter 17,
Flowing through 18. If the frequency of the rf current is f1 and f
2 and if given to the central and outer electrodes 1 and 2, respectively, the rf filter 17 has a frequency f
The rf current of 2 is removed, and the rf filter 18 has the frequency f1.
Rf current is removed. Therefore, the rf current of each of the rf generators 13 and 14 does not flow into the other rf generators. This is important for the safety of the electrical circuits of the rf generators 13,14. However, if the r of both rf generators
If the f frequencies are the same, the rf filters 17, 18
Can be omitted.

Any conventional wafer holder may be used as the wafer holder 19. Wafer holder 19
Are fixed to the bottom plate 23. Usually, the wafer holder 19 is a dielectric member including an rf electrode. This rf electrode corresponds to the lower electrode 3 described above. The rf electrode becomes the third electrode in the four-electrode type plasma device. The lower electrode 3 is embedded in the wafer holder 19 and covered with the dielectric member 42. In addition, the wafer holder 19 may include a cooling or heating mechanism (not shown in the figure). The lower electrode 3 is disposed on the dielectric member 20 to electrically insulate it from the rest of the reaction vessel. The lower electrode 3 is supplied with an rf current from an rf generator 22 through a matching circuit 21. However, the structure for applying the rf current to the lower electrode 3 can be omitted. The frequency of the rf current is not critical and lies in the range 500 KHz to 15 MHz. The purpose of applying rf power to the lower electrode is to generate a self-biased DC voltage on the lower electrode 3. If no rf power is applied, the bottom electrode 3 is either electrically grounded or floating. The electrical state of the bottom electrode 3 is not critical to this embodiment or the expected application and thus can vary depending on the type of wafer processing.

The cylindrical side wall 4 of the reaction vessel is electrically grounded and acts as a fourth electrode. Because the inner surface of the side wall 4 is in contact with the plasma, the double concentric rf
This is because the electrodes (1, 2) and the lower electrode (3) collect all the rf currents entering the plasma by the capacitive coupling mechanism. However, a ground shield placed inside the sidewall may be used as the ground electrode for the purpose of collecting the rf current from the plasma. The use of the shield facilitates the reaction vessel cleaning procedure, as the shield can be easily removed from the reaction vessel. In particular, it is advantageous when the chemical constituents of the plasma processing gas deposit any unwanted films on the surface of the shield.

In addition, the wafer transfer port 25 is formed on the cylindrical side wall 4, and the exhaust port 6 is formed on the lower side of the side wall 4.

In the structure shown in FIG. 1, two rf
When an electric current is applied separately to the central and outer rf electrodes 1, 2, plasma is generated in the reaction vessel by a capacitive coupling mechanism. It should be noted that the mechanism of plasma generation by both rf electrodes 1, 2 is a capacitive coupling process regardless of the frequency of the rf current adopted. The plasma density and radial distribution of the plasma in any desired plane between the upper electrode (1, 2) and the lower electrode 3 depends on the frequency and power of the applied rf current.

FIG. 2 shows the radial shape of the plasma generated near the upper center and the outer rf electrodes 1 and 2.
If the rf current is applied only to the central rf electrode 1, the plasma density has a peak at the center and decays toward the side wall 4 of the reaction vessel. This is indicated by the curve labeled 26. This smooth pyramidal shaped plasma becomes even more non-uniform as it moves towards the lower electrode 3 as the plasma diffusion moves towards the sidewalls. The change in inhomogeneity depends on the pressure and the applied r
f power. Similarly, if an rf current is applied only to the outer rf electrode 2, a donut-shaped plasma is generated below the outer rf electrode 2. The radial shape of this plasma is shown by the curve labeled 27 in FIG. When the rf currents are simultaneously applied to the central and outer rf electrodes 1 and 2, both plasmas described above are generated. Since these two plasmas make one plasma by the diffusion process, the radial shape of the resulting plasma will be different from the shape of the individual plasmas. Due to the presence of the doughnut-shaped plasma, the radial plasma uniformity of the resulting plasma is improved as shown by the curve labeled 28 in FIG. The overlapping area between the periphery of the plasma (26) and the inner edge of the plasma (27) is
Create a flat radial shape for the synthesized plasma. The two rf powers applied to the upper center and outer rf electrodes 1, 2 are independently varied until a plasma is created with the required radial distribution uniformity.

The quadrupole plasma processing apparatus of the above embodiment obtains a plasma having the required radial plasma uniformity on a large area wafer placed on the lower (ie third) electrode 3. To facilitate. This can be achieved by controlling the rf power applied to the double concentric rf electrodes 1, 2, or by properly selecting the frequency of the rf current applied to the double concentric rf electrodes 1, 2.
Alternatively, it can be achieved by using both of these methods.

Next, a second embodiment will be described with reference to FIG. The configuration of the second embodiment is such that the dielectric or high-resistance semiconductor plate 2 is provided below the central and outer electrodes 1 and 2.
It is the same as that described in the first embodiment except that 9 is added. Therefore, only the characteristics of the dielectric plate 29 and its role in this device are described. The thickness of the dielectric plate 29 is not an important matter, and is 1 to 10
It can be in the range of mm. Moreover, the type of dielectric (eg, quartz, SiN, Teflon, silicon, etc.) and the dielectric constant used for the dielectric plate 29 are likewise and not critical. The material thickness and its type are selected depending on the type of application. Process gas is rf
It is introduced through the electrodes 1 and 2 and a plurality of gas introduction ports 5 formed in the dielectric plate 29. This dielectric plate 29
The purpose of is described below.

The center and outer r described in the first embodiment
The f electrodes 1 and 2 are not covered with any material. Therefore, the metallic material from which the electrodes 1, 2 are made is exposed to the plasma. When plasma is generated, a self-biased DC voltage is generated on the rf electrodes 1 and 2. If these DC voltages are high enough, the ions in the plasma gain energy and strike the metal surface of electrodes 1, 2 and result in sputtering of the rf electrode surface.
This contaminates the plasma and the wafer surface, resulting in defective devices. Therefore, the configuration given in the first embodiment is only applied at lower rf power, or where there is no problem with metal sputter for wafer processing. In particular, the configuration of the first embodiment is suitable for plasma-assisted chemical vapor deposition.

For the above-mentioned reason, the central and outer rf electrodes 1 and 2 arranged on the upper side in the second embodiment are covered with the dielectric plate 29. The dielectric plate 29 is made of a suitable dielectric material. Dielectric plate 2
Instead of 9, a semiconductor member that does not cause any problems due to the sputtering process may be used as the cover plate. For example, high-resistivity silicon or quartz can be used for dielectric etching processes because sputtered silicon reacts with other gases in the reaction vessel to form gas species, which therefore causes no problems for the process considered. It is useful. In addition, this configuration may be used in dielectric or semiconductor sputter deposition applications. In this case, the dielectric or semiconductor plate is made of a material that needs to be sputtered with or without chemical reaction in the plasma state and deposited on the wafer surface. However, if this configuration is used in a sputter deposition application, the process gas must be introduced into the sidewall 4 or through a gas inlet made on the bottom plate 23. There should be no gas inlet above the dielectric or semiconductor plate 29 located below the central and outer rf electrodes 1, 2.

Next, a third embodiment will be described with reference to FIG. This figure shows a schematic diagram of the third embodiment. The configuration of the third embodiment is particularly suitable for metal sputter film formation. Here, the central and outer rf electrodes 1, 2 are made of metal, for example copper, which needs to be sputtered and deposited on a wafer mounted on a wafer holder 19. . If the configuration given in the first embodiment is used for metal sputter deposition, rf
Metal atoms sputtered from the electrodes 1, 2 are deposited on the lower surface of the dielectric rings 7, 8. These dielectric rings 7, 8 are respectively between the rf electrodes 1, 2 and between the outer rf electrode 2 and the grounded wall. This is rf
The result is an electrical connection between the electrodes (1, 2) and ground. Between rf electrodes 1 and 2, and outside rf
In order to prevent the formation of a continuous metal film between the electrode 2 and the ground, the configuration of the dielectric rings 7 and 8 in the third embodiment is changed as shown in FIG.
For the purposes described above, deep grooves or gaps 30 have been formed on the inner and outer surfaces of each of the dielectric rings 7, 8 which are adjacent to each of the rf electrodes 1, 2. These grooves 30 have a circular shape around the rf electrodes 1 and 2. The thickness and width of the groove are usually 2 mm or less, and the height or depth depends on the thickness of the rf electrodes 1 and 2. Its height may range from 10 mm to 40 mm. Since the sputtered metal atoms cannot reach the upper part of the deep trench 30, a continuous metal film cannot be deposited. In this way an electrical connection is prevented from being formed between the rf electrode (1, 2) and ground.

The center and outer rf electrodes 1 and 2 have the rf generators 13 and 1, respectively, as described in the first embodiment.
Rf power from 4. In addition, the rf electrodes 1 and 2
Of the rf cut filter (33, 3
It is connected to the DC voltage supply devices 31, 32 via 4). The purpose of applying the DC voltage is to provide a negative bias voltage on the rf electrodes 1, 2 to increase the sputter rate. The DC voltage values applied to the central and outer rf electrodes 1 and 2 from the DC voltage supply devices 31 and 32 are different and are not important. If the self-bias voltage generated by the rf plasma is sufficient to have the required sputter rate, this configuration may be used without the DC voltage supplies 31, 32.

In addition, the plurality of gas inlets formed in the central and outer rf electrodes 1 and 2 shown in the first embodiment are omitted in the third embodiment. instead of,
The process gas is introduced through several gas inlets made around the cylindrical side wall 4 of the reaction vessel, as shown in FIG. For this purpose, a circular tube 36 with several gas inlets 35 is fixed to the cylindrical side wall 4. At that time, the process gas is the main gas introduction part 3
It is supplied to the circular tube 36 via 7.

However, instead of the structure described above,
Different mechanisms for supplying the process gas can be used. For example, the process gas may be supplied via a single gas introducing pipe formed on the bottom plate 23. Except for the modifications described above, all other configurations are the same as in the first embodiment.

The operating procedure of the sputtering apparatus is also the same as that described in the first embodiment. Rf provided to the center and outer rf electrodes 1 and 2 to obtain the required properties of the deposited film, such as film uniformity and deposition rate.
The current and DC voltage can be changed appropriately.

The fourth embodiment will be described with reference to FIGS. 5, 6 and 7. This configuration is obtained by replacing the outer rf electrode 2 in the second embodiment with a single loop rf antenna 38 made of metal. Central r
A top view of the f-electrode 1 and the single loop rf antenna 38 is shown in FIG.
Shown in. One end of the single loop rf antenna 38 is rf
Rf generator 43 via filter 18 and matching circuit 44
It is connected to the. The other end of the single loop rf antenna 38 is grounded. The frequency of the rf generator 43 connected to the single loop antenna 38 is not critical and is typically in the range 500 KHz to 20 MHz. Normal,
Lower rf frequencies are more convenient for single loop rf antenna 38 for the following reasons.

The purpose of the single loop rf antenna 38 is to create an inductively coupled plasma below the single loop rf antenna 38. For this purpose, the impedance of the induced rf current should be minimized. If the induction of the single loop rf antenna 38 is L and the impedance of the induced current is Z _L , then Z _L = i · 2
πf · L, where f is the frequency of the rf current.
Therefore, if the frequency f is reduced, Z _L will be reduced, which intensifies the induced current flowing from the single loop rf antenna 38 into the plasma.

Even if one of the two ends of the single loop rf antenna 38 shown in FIG. 6 is electrically grounded, its end is a capacitor C1 as shown in FIG.
Can be connected to the ground via. This configuration is usually
It creates a smaller potential difference between the ends of the single loop rf antenna 38 compared to the configuration shown in FIG. This is important to reduce the circumferential (azimuth) variation in plasma density below the single loop rf antenna 38.

The thickness of the single loop rf antenna 38 is typically less than 2 mm. The bottom portion of the single loop rf antenna 38 facing the plasma may be sharpened to have knife edges as shown in FIG. This is to reduce the possibility of capacitive coupling of rf power to the plasma.

The lower surface of the central rf electrode 1 and the single loop rf antenna 38 are covered by the dielectric plate 29, as described in the second embodiment. However, the dielectric plate 29 is not essential,
Therefore, it is also possible to use a configuration without the dielectric plate 29.

Plasma is generated in the central region by the capacitive coupling mechanism of rf power from the central rf electrode 1 to the plasma. In addition, a donut-shaped plasma is generated below the single loop rf antenna 38 by an inductive coupling mechanism. This configuration results in an increase in plasma density in the reaction vessel as compared to those in the previously described embodiments, as the inductive coupling mechanism creates a higher plasma density. The operation procedure of this configuration is the same as the procedure described in the previous embodiment.

The fifth embodiment is an extension of the fourth embodiment and is intended for metal sputter film formation application. A schematic diagram of the fifth embodiment is shown in FIG. As described in the third embodiment, in order to avoid depositing a continuous metal film on the surfaces of the dielectric rings 7 and 8,
Grooves or gaps are made in the lower surface of the dielectric rings 7,8.

Further, a plurality of gas introduction ports on the central rf electrode 1 are omitted. Instead, the process gas is introduced through a gas inlet made in the cylindrical side wall of the reaction vessel as described in the third embodiment. Except for these changes, all other hardware configurations are the same as those given in the fourth embodiment.

Some metal deposition processes require a high density plasma to ionize sputtered atoms from the top electrode 1 before depositing the film on the wafer surface. For these applications, the inductively coupled plasma created below the single loop rf antenna 38 creates a high density plasma, so the configuration given in the fifth embodiment is used.

The sixth embodiment will be described with reference to FIG. This configuration is an extension of the second embodiment shown in FIG. Here, r connected to the double concentric rf electrodes 1 and 2
f The power supply circuit is changed. The same frequencies (f1, f2) shown in FIG. 9 are adopted as the frequencies of the rf generators 13, 14. The rf currents from the rf generators 13 and 14 are supplied to the central and outer rf electrodes 1 and 2 via the matching circuits 15 and 16 and the phase shifters 45 and 46. By using the phase shifters 45 and 46, respectively, the phase of the rf current coming from each rf generator (13, 14) can be arbitrarily changed. In FIG. 9, phase shifters 45, 4
6 is arranged between the matching circuits 15 and 16 and the rf electrodes 1 and 2, respectively. However, a phase shifter can be placed between the rf generator and the matching circuit to achieve the same result as described below. Except for the modified parts described above, all other hardware of the sixth embodiment is the second hardware.
It is the same as that given in the embodiment.

The phase shifters 45 and 46 are connected to the plasma density,
It is used to change plasma characteristics such as plasma potential and plasma uniformity. Normally, when plasma is generated by the capacitive coupling mechanism, the rf current coming from the rf electrode flows to the ground electrode. However, if the same rf frequency and 180 degrees out of phase rf
If there are other rf electrodes operating with current, the rf currents coming from the two electrodes 1, 2 will flow to each other. Therefore, if the rf currents of the central and outer rf electrodes 1 and 2 are 180 degrees out of phase, the rf current will flow between these two electrodes. This causes the plasma to be confined in the region between the central and outer rf electrodes 1, 2 and limits the expansion of the plasma towards the lower electrode. This has the potential to reduce the plasma potential in the vicinity of the wafer surface.

It is difficult to monitor the exact phase shift of the rf current on the bottom surfaces of the central and outer rf electrodes 1, 2 towards the plasma. Because the phase shifter 4
This is because the parasitic inductance (induction component) and capacitance (capacitance component) of the transmission line after 5 or 46 cause a phase change of the rf current. Therefore, a practical experiment must obtain the proper phase shift. First, the plasma is generated by the central and outer rf electrodes 1,
2 by providing an rf current. The phase of the rf current coming from either rf generator 13 or 14 is then slowly changed until the desired plasma characteristics are obtained. The characteristics of plasma are the same as those of the conventional Langmuir probe (Reference: D.
N. Ruzic, Electric probes for for low temperature p
lasmas, AVS pres, USA, 1994) or plasma absorption probe (Reference: H.Kokura, K.Nakamura, I.Ghanas)
hevand H. Sugai, Jpn. J. Appl. Phys. 38, 5262 (199
9)). In some cases, the change in the optical emission intensity of the plasma is r
It may give some information that changes the phase of the f-current. This experiment has to be done only once, after the relevant data have been obtained, they are used for subsequent wafer processing.

Even if r is adopted in the sixth embodiment,
Even if the mechanism of f current flow is explained using the configuration given in the second embodiment, the same rf
The current flow mechanism can be applied to the configurations given in the first and third embodiments. because,
Central and outer rf in the first, second and third embodiments
This is because the electrodes generate plasma by the capacitive coupling mechanism.

The characteristic technical matters described in the above-described embodiments can be combined as appropriate in order to achieve the object of the present invention.

[0056]

According to the plasma processing apparatus of the present invention, the improved structure including the double concentric rf electrodes, that is, the central and outer rf electrodes can control the plasma density, and the plasma density in the radial direction of the reaction vessel. It is useful for processing large area wafers because it can achieve uniformity of

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 shows a radial distribution shape of plasma densities generated simultaneously and separately by the central and outer rf electrodes according to the first embodiment.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

FIG. 4 is a sectional view showing a third embodiment of the present invention.

FIG. 5 is a sectional view showing a fourth embodiment.

FIG. 6 shows a central rf electrode according to the fourth embodiment,
FIG. 6 is a top view of a single loop antenna, dielectric ring, rf electrical connection.

FIG. 7 shows a central rf electrode according to the fourth embodiment,
FIG. 6 is a top view of a single loop antenna, dielectric ring, rf electrical connection.

FIG. 8 is a sectional view of the fifth embodiment.

FIG. 9 is a sectional view of a sixth embodiment.

FIG. 10 shows a conventional parallel plate capacitively coupled plasma source.

FIG. 11 is a change in distribution profile of radial plasma density in the conventional plasma source shown in FIG.

[Explanation of reference symbols]

1 Central rf electrode 2 outer rf electrode 3 Lower electrode 4 side walls 5 gas inlet 6 exhaust port 7,8 Dielectric ring 9,10 Gas reservoir 13,14 rf generator 15,16 Matching circuit 17,18 rf filter 19 Wafer holder 26, 27, 28 Radial shape of plasma density 30 deep circular groove 31 DC voltage supply 33,34 rf cutoff filter 38 single loop rf antenna 39 channels 45,46 Phase shifter

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4K029 AA06 AA24 BD01 CA13 DA06                       DC35                 4K030 CA04 CA12 EA06 FA03 FA04                       JA10 JA18 JA19 KA16 KA20                       KA41                 5F045 AA08 BB02 EB02 EF05 EH04                       EH05 EH08 EH12 EH13 EH19                       EJ05

Claims (9)

[Claims] 1. Double concentric rf for plasma generation by capacitive coupling mechanism or capacitive and inductive coupling mechanism.
An electrode, wherein the center r of the double concentric rf electrode
The f-electrode has a circular shape or a shape close to a circular shape, while the outer rf electrode of the double concentric rf electrode has the central rf electrode.
The double concentric rf electrode arranged around the electrode, a dielectric member arranged between the central and outer rf electrodes, and a matching circuit and an rf filter for the central and outer rf electrodes Two rf generators connected to each other, a third flat plate rf electrode as a wafer holder arranged on a lower plane parallel to the double concentric rf electrode, and a fourth electrode as a fourth electrode. A plasma processing apparatus for large-area wafer processing, which comprises a reaction container side wall that is electrically grounded. 2. The plasma processing apparatus for large area wafer processing according to claim 1, wherein the outer rf electrode has a wide flat surface facing the plasma to generate plasma by a capacitive coupling mechanism. 3. The plasma processing apparatus for large area wafer processing according to claim 1, wherein a single loop antenna is used instead of the outer rf electrode to generate plasma by an inductive coupling mechanism. 4. The central and outer r facing the plasma
The plasma processing apparatus for large area wafer processing according to claim 1 or 2, wherein the lower surface of any one of the f electrodes or both lower surfaces thereof are covered with a dielectric member or a semiconductor member. 5. One of the central and outer rf electrodes
5. The plasma processing apparatus for large area wafer processing according to claim 1, wherein one or both of them includes a gas reservoir and a plurality of gas inlets for introducing a process gas into the reaction chamber. 6. The plasma processing apparatus for large area wafer processing according to claim 1, wherein the central and outer rf electrodes include a mechanism for controlling the surface temperature of the central and outer rf electrodes. 7. The dual concentric rf electrode operates separately at two different rf generators operating at the same rf frequency or at two different rf frequencies and the frequencies being in the range of 1-100 MHz. The plasma processing apparatus for large area wafer processing according to claim 1, wherein two rf currents are supplied. 8. Each of the center and outer rf electrodes is r
The rf generator and the DC voltage supply are respectively supplied with an rf current and a DC voltage negatively biased, and said rf generator and DC voltage supply connected to one electrode are connected to another rf electrode. Claim 1 independent of those
7. A plasma processing apparatus for large-area wafer processing according to any one of items 6 to 6. 9. The large area wafer according to claim 1, wherein each rf electrode of said double concentric rf electrode is connected to a corresponding rf generator through a matching circuit and a phase shifter. Plasma processing equipment.