KR20080112080A - Multi-station decoupled reactive ion etch chamber - Google Patents

Abstract

A separated multistation reactive ion etching chamber is provided to process two wafers, at the same time, by having a isolated process area. A plasma processing chamber(100) has two or more process areas for discrete or simultaneous processing of two or more wafers(130,135). The plasma processing chamber comprises a chamber body(105), a vacuum pump(180), and a RF matching circuit(153,157). The chamber body limits two or more plasma process areas and an exhaust duct. The plasma process area comprises cathode installed in a lower part and anode installed at a ceiling respectively. The vacuum pump is connected to the exhaust duct. RF unites combine at least one of cathodes to the first radio frequency and the second radio frequency at the same time. The first frequency is higher than the secondary frequency.

Description

Separated multistation reactive ion etch chamber {MULTI-STATION DECOUPLED REACTIVE ION ETCH CHAMBER}

The present invention relates to a plasma processing chamber, and more particularly to a plasma processing chamber comprising at least twin or tandem processing regions that enable processing of at least two substrates at the same time. It is about.

In the manufacture of semiconductor wafers, two forms of semiconductor processing systems are commonly employed. The first type of system commonly used is commonly referred to as batch processing systems. The main factor in the development of a batch processing system is that several wafers are processed simultaneously and thus provide high throughput. However, due to the strictness of performance specifications, the industry has moved to a second form of process chamber, namely single-wafer processing chambers. The main factor in the development of a single wafer processing system is that it is easier to control the process characteristics and uniformity of the wafer.

Meanwhile, in some niche markets, attempts have been made to produce process chambers capable of processing two wafers at once. The idea for this approach is to process two wafers at once, while enabling single wafer processing characteristics. One configuration for twin / tandem wafer processing is disclosed in US Pat. No. 5,811,022, which is an inductively coupled plasma chamber used for plasma photoresist removal, also known as photoresist ashing. (inductively coupled plasma chamber) is disclosed. Photoresist ashing is an oxidation process that uses oxygen to remove organic photoresist. The photoresist is oxidized to gases such as carbon monoxide, carbon dioxide, and water vapor, which is then removed by a vacuum pump. Thus, such applications do not require as high accuracy for the process uniformity of the wafer as for more stringent applications such as semiconductor wafer etching.

Since the process requirements of photoresist ashing are not stringent, the chamber shown in US Pat. No. 5,811,022, which includes two separate plasma generating chambers, has both bottoms open toward the process chamber containing the wafer. In order to prevent the charged particles from reaching the process chamber, a charged particle filter is provided between the plasma chamber and the process chamber, but in order to remove the photoresist from the wafer, neutral activated species are added to the process chamber. have. Since the process chamber has no separation between the two wafers and no plasma can be ignited on the wafer, the chamber of US Pat. No. 5,811,022 provides simple ashing, especially since a filter is provided to remove charged particles from the wafer process chamber. Can be used, but not in modern stringent applications such as semiconductor wafer etching.

Another tandem process chamber is disclosed in US Pat. No. 5,855,681. The process chamber disclosed in US Pat. No. 5,855,681 includes two processing regions for simultaneously processing two wafers, and a separate gas distribution assembly (") to provide uniform plasma density to the wafer surface in each etching processing region. gas distribution assemblies and RF power sources ". In particular, the authors of U.S. Patent No. 5,855,681 explain that the unsatisfactory result provided by the Mattson system (described above in U.S. Patent No. 5,811,022) is "a direct result of allowing multiple wafers to be partially processed at multiple stations in a single chamber." do. To improve this design, U. S. Patent No. 5,855, 681 states that the chamber should have “isolated processing regions”. This teaches that at least two separate regions can be processed simultaneously and at least two wafers can be processed simultaneously.

The solution of isolating the processing area allows tandem processing of two wafers at the same time, while presenting the difficulties commonly referred to as chamber matching or station matching. That is, it becomes difficult to control two processing regions of the chamber to provide the same plasma processing conditions. For example, if one processing region develops at a higher etch rate than another region, it becomes difficult to control the end point of the etching process. In other words, if the end point is determined according to the higher etching rate, the other wafer will not be fully etched. Conversely, if the end point is delayed, the wafer in the higher etch rate region is overetched and damaged.

An improved version of this tandem chamber is disclosed, for example, in US Pat. No. 6,962,644, which proposes a "chamber defining a plurality of isolated treatment regions." In US Pat. No. 6,962,644, "central pumping plenum" causes the two chambers to "connect" to each other, causing a problem known as RF "crosstalk." RF crosstalk is detrimental to tandem processing because the change in conditions in one treatment region adversely affects the process of the second tandem region.

The isolated tandem chamber described above has a problem with isolation, which makes it difficult to match the treatment results between the two treatment regions. In addition, the tandem chamber disclosed in US Pat. No. 6,962,644 uses two RF power supplies of fixed phase and frequency to prevent beating of RF power from two sources. This complicates the structure and configuration of the chamber. Finally, the method of generating plasma in the tandem chamber described above does not meet the stringent performance specifications required to fabricate advanced semiconductor devices. Accordingly, there is a need in the art for multiple wafer chambers that allow for a high level of performance while matching the performance of each treatment region of the chamber.

The following summary of the invention is provided for a basic understanding of certain aspects and features of the invention. This summary is not an extensive overview of the invention, and is not particularly intended to identify key or critical components of the invention or to delineate the protection scope of the invention. Its sole purpose is to present the concepts of the invention in a simplified form as a prelude to the more detailed description that is presented below.

 Various embodiments of the present invention provide at least twin or tandem treatment region chambers with plasma isolation and frequency isolation so that multiple RF frequencies can be supplied from below for each treatment region. The chamber wall is grounded, and the partition wall between the two treatment regions is also grounded. The use of frequency isolation allows the supply of multiple RF frequencies from the cathode without crosstalk or beating. Plasma confinement rings are used to prevent plasma crosstalk. In addition, a grounded common exhaust passage connected to a single vacuum pump is provided.

A micro-channel ring structure is provided at the inlet of the exhaust path so that the plasma is confined to the treatment area, so that the plasma does not reach the exhaust path and there is no crosstalk between the treatment areas. The microchannel also aids in pressure distribution since a single pump forms asymmetric pumping. The ring also prevents RF radiation leakage between the two treatment areas. The ring is made so that the top is an insulator so that there is no plasma sputtering, but the bottom is conductive and grounded to prevent RF leakage.

Since the plasma confinement of the chamber prevents beating, there is no need to fix the phase and frequency of the RF power supply. In addition, because of plasma confinement and RF separation, each treatment region may be operated alone or in combination.

According to one aspect of the present invention, there is provided a plasma processing chamber having at least two processing regions that allow for the individual or simultaneous processing of at least two wafers, each plasma processing chamber mounted on a cathode and a ceiling disposed below each other. At least two plasma processing regions comprising an anode and a chamber body defining an exhaust passage; At least one vacuum pump connected to the exhaust passage; And at least two RF matching circuits respectively coupling at least a first RF frequency and a second RF frequency to one of the cathodes, wherein the first frequency is higher than the second frequency.

Here, the plasma processing chamber may further include at least two plasma confinement rings, each of which is installed around a corresponding cathode and prevents plasma transfer from the processing region to the exhaust passage. In this case, each of the plasma confinement rings may include a plasma shield and an RF shield, the plasma shield is conductive but is electrically floating, and the RF shield is grounded conductive. It may be made of a material.

In addition, the plasma process chamber of the present invention may further comprise two movable insulating isolation rings. It is provided in one treatment area each, and serves to define a peripheral boundary of each treatment area when in the lower position, respectively. It is then preferred that the chamber body provides a grounded chamber wall in each processing area, and each isolation ring has a thickness designed to shield the grounded chamber wall from RF energy. In addition, each isolation ring may further comprise at least one pressure balancing passage. Furthermore, the plasma process chamber of the present invention further comprises a separating wall separating each of the two processing regions, the separating wall comprising a pressure balancing channel, the pressure balancing channel having the isolation ring in a lower position. When in communication with the pressure balancing passage.

In addition, the plasma process chamber of the present invention further comprises a plurality of RF conductors, each of which combines energy from one RF matching circuit into a corresponding cathode, each of the RF conductors being adapted to each other in the same manner. It may have a plurality of branches spaced at the same radial distance to engage on the cathode. In this case, each of the RF matching circuit, a high frequency input, a low frequency input, a combined output, a high frequency matching circuit connected between the high frequency input and the combined output, a low frequency matching circuit connected between the low frequency input and the combined output. Wherein the high frequency matching circuit exhibits high impedance at the second and fourth frequencies, and the low frequency matching circuit exhibits high impedance at the first and third frequencies.

Here, the first frequency may be selected from 27 MHz, 60 MHz, and 100 MHz, and the second frequency may be selected within a range of 500 KHz to 2.2 MHz.

Furthermore, each of the RF matching circuits may further couple the third RF frequency to the corresponding cathode. In this case, the plasma processing chamber may further comprise a plurality of switches each operating to select one of the first, second and third RF frequencies.

According to another aspect of the present invention, there is provided a system comprising: defining a first processing region and a second processing region; A partition wall separating the first processing region and the second processing region; An exhaust chamber including a single exhaust port and in fluid communication with said first processing region and said second processing region; A conductive chamber body connected to ground potential; A vacuum pump connected to the exhaust port; A first fixed cathode fixed to the lower portion of the first processing region and including a first chuck supporting the wafer; A first shower head fixed to a ceiling of the first processing region and including a first electrode; A second fixed cathode fixed to the bottom of the second processing region and including a second chuck supporting the wafer; A second shower head fixed to the ceiling of the second processing region and including a second electrode; A common gas source providing process gas to the first showerhead and the second showerhead; A first RF matching circuit for simultaneously coupling at least one low RF frequency and at least one high RF frequency to the first cathode; And a second RF matching circuit for simultaneously coupling at least one low RF frequency and at least one high RF frequency to the second cathode, wherein the high RF frequency is at least twice as high as the tandem plasma etch chamber. A tandem plasma etch chamber is provided.

The tandem plasma etching chamber may include: a first plasma confinement ring disposed around the first cathode and preventing plasma transfer from the first processing region to the exhaust chamber; And a second plasma confinement ring installed around the second cathode and preventing plasma transfer from the second processing region to the exhaust chamber. In this case, each of the first and second plasma constraining rings may include a plasma shield and an RF shield. Further, the plasma shield may be conductive but include a floating member, and the RF shield may include a grounded conductive member.

The tandem plasma etching chamber of the present invention also includes a movable first insulating isolation ring provided in the first processing region; And a movable second insulating isolation ring provided in the second processing region, wherein the first and second isolation rings can take an upper position during wafer loading and a lower position during wafer processing. Here, each of the first and second isolation rings preferably has a thickness designed to shield the grounded chamber wall from RF energy. In addition, each of the first and second isolation rings may further include at least one pressure balancing passage. In this case, the dividing wall includes a pressure balancing channel, which allows the pressure balancing channel to communicate with the pressure balancing passages of the first and second isolation rings when the first and second isolation rings are in a lower position. have.

Further, in the tandem plasma etching chamber of the present invention, the low frequency may be selected within the range of 500 KHz to 2.2 MHz, and the high frequency may be selected from 27 MHz, 60 MHz, and 100 MHz.

The tandem plasma etching chamber of the present invention further includes a first switch connected to the first RF matching circuit and a second switch connected to the second RF matching circuit, each of the first and second switches. May operate to select the low RF frequency from a selection of two low RF frequencies, or to select the high RF frequency from a selection of two high RF frequencies.

On the other hand, in the tandem plasma etching chamber of the present invention, each of the first processing region and the second processing region is operable independently of each other.

According to another aspect of the present invention, a plurality of processing regions are defined; Having a separating wall comprising a fluid transfer channel for separating the plurality of processing regions from each other and equalizing the pressure between the processing regions; And an exhaust chamber in fluid communication with the processing regions; A conductive chamber body connected to ground potential; At least one vacuum pump connected to the exhaust chamber; A plurality of cathodes each fixed to a lower portion of a corresponding one of said processing regions, said plurality of cathodes comprising a chuck for supporting a wafer; A plurality of showerheads fixed to a corresponding one ceiling of said processing region and comprising electrodes; A common gas source providing process gas to the showerhead; And a plurality of RF matching circuits, each simultaneously connecting at least one low RF frequency and at least one high RF frequency to a corresponding one of the cathodes, a decoupled reactive ion etch chamber.

Here, the separate reactive ion etch chambers may further comprise a plurality of plasma confinement rings, each installed around a corresponding cathode, to prevent plasma transfer from one processing region to the exhaust chamber. In this case, each plasma constraining ring may include a plasma shield and an RF shield. Further, the plasma shield may be conductive but include a floating member, and the RF shield may include a grounded conductive member.

In addition, the separate reactive ion etching chambers of the present invention may further comprise a plurality of movable insulating isolation rings, each provided in one processing region, each defining a peripheral boundary of each processing region when in the lower position. have. Each isolation ring then preferably has a thickness designed to shield the grounded chamber wall from RF energy. Further, each isolation ring may further include at least one pressure balancing passage in communication with the fluid delivery channel when the isolation ring is in the lower position.

Embodiments of the present invention provide a multipurpose plasma chamber that allows for accurate and uniform processing at high throughput. By combining various forms and components to enable stable and uniform plasma in each processing region, the processing results meet the demanding requirements of advanced semiconductor fabrication. In particular, the combination of the forms provided herein enables multi-station reactive ion etching (RIE) separated by a multi-frequency RF power source applied to each processing region. Various forms and measures are provided to avoid RF crosstalk and frequency beating between the two tandem treatment regions. In particular, no tandem chamber has ever been proposed in which separate RIE is enabled by the use of two RF frequencies supplied from the cathode for each treatment area.

1 is a schematic cross-sectional view of a tandem plasma chamber 100 according to an embodiment of the present invention, Figure 2 is a cross-sectional view taken along the line C-C of FIG. It will be described in detail with reference to these two drawings. The chamber body 105 is generally made of a metallic material, such as aluminum, and defines two tandem treatment regions 110 and 115. The treatment regions 110 and 115 are physically separated by the dividing wall 122. However, as described below, a pressure balancing mechanism is provided to equalize the pressure between the two treatment regions 110 and 115. The chamber body including the dividing wall 122 is grounded to provide isolation of the electric field between the two treatment regions 110 and 115, thereby avoiding RF crosstalk.

Each of the processing regions 110 and 115 is provided with cathodes 120 and 125 which are fixed to support the wafers 130 and 135 during processing. In the present embodiment a fixed cathode is used because it allows for better grounding than the movable cathode. Since both frequencies are supplied from the cathode in this embodiment, efficient grounding is important. Therefore, the use of a fixed cathode is advantageous in this embodiment.

Cathodes 120 and 125 include a chucking mechanism to hold the wafer in place. The chucking mechanism may be any conventional chuck, such as a conventional electrostatic chuck. In addition, cathodes 120 and 125 include buried electrodes for radiating RF energy to the processing region. RF energy is supplied to the cathode by RF conductors 140 and 145. Each RF conductor is connected to two RF power supplies, with RF conductors 140 connected to 152 and 154, RF conductors 145 connected to 156 and 158 via matching circuits 153 and 157, respectively. According to this embodiment, the distribution of RF power to the cathode is done equally, which in this embodiment is a three-branch coupler each comprising three connectors (although only two are shown in cross section) that are 120 ㅀ apart from each other ( 150 and 155).

According to this embodiment, separate RIEs are made possible by the use of two RF frequencies applied to each cathode, where the two frequencies are sufficiently separated so that the RF power from the two power supplies is separated. For example, the ratio of high frequency to low frequency is set to about 10 or more. This ensures isolation between the two frequencies. In one example, the low frequency is selected in the range of about 500 KHz to 2.2 MHz. In a particular example, the low frequency is set to about 2 MHz while the second frequency is set to about 27 MHz. In another example, the low frequency is set to about 2 MHz, while the second frequency is set to about 60 MHz or 100 MHz.

According to the present embodiment, the interference between the processing regions 110 and 115 can be partially avoided by using frequency tuning for the RF power supply. This allows for fast tuning (e.g., shorter than one second response) so that any disturbances in one treatment area do not adversely affect the treatment of adjacent tandem areas. According to one embodiment, high efficiency, self isolation RF matching circuits 153 and 157 are provided, each coupling two RF signals to a cathode of one processing region. For this purpose, the RF matching disclosed in US Patent Application Publication No. 2005/0133163 can be used. However, RF matching disclosed in US Patent Application Publication No. 2005/0133163 requires the use of a filter that further complicates the structure of the RF matching. Therefore, it is more advantageous to utilize RF matching as disclosed in US 2007/0030091, which is hereby incorporated by reference in its entirety. The new design of RF matching of US Application Publication No. 2007/0030091 does not require a filter.

5 is a conceptual diagram of an RF matching network structure that does not require the use of a filter, which may be employed in the chamber of the present invention. As shown, this embodiment has two RF inputs, one high frequency input and the other low frequency input. The RF matching network has three ports, two of which are input ports: a high frequency input port connected to a high frequency RF generator such as 158 and a low frequency input port connected to a low frequency RF generator such as 156, and one 145. RF output port for outputting the energy of the multiple RF generator to the vacuum process chamber via a conductor such as. The RF matching network of the vacuum process chamber can be divided into a low frequency part and a high frequency part, which are collected at a single connection point at the output port. The high frequency portion includes grounded capacitor C1 ', capacitor C2' and inductor L '. The low frequency portion also includes one terminal grounded through capacitor C1 and another terminal connected to capacitor C2 connected in series with inductor L to an output port through inductor L.

In the low frequency portion, inductor L, capacitor C1 and capacitor C2 form a low pass filter, while in the high frequency portion, inductor L ', ground capacitor C1' and capacitor C2 'form a high pass filter. If the frequency of the high frequency input is much higher than the frequency of the low frequency input, i.e., the frequency of the high frequency input is about 10 times the frequency of the low frequency input, the characteristics of the high pass filter and the impedance of the vacuum process chamber under the high frequency input Due to the nature, a small inductance in the high frequency part is required to realize a conjugate match between the entire matching network and the vacuum process chamber. Also under certain circumstances it is appropriate to use a conducting piece, such as a connecting wire, which does not provide any physical inductor in the high frequency portion but has a conductive connector extending from the RF output port to the lower electrode of the vacuum process chamber. . This replaces the inductor. In this configuration, the magnetic inductance of the conductive segments and the conductive connector is substantially equivalent to the inductor. In this case the ground capacitor C1 'may be replaced by a conductive piece and a parasitic capacitor between the conductive connector and ground. Since the parasitic capacitors C1 'and L' have a small value and are not easily tuned, the capacitor C2 'of the high frequency portion can be provided as a variable capacitor for adjusting the impedance of the circuit.

The values of the capacitors and inductors can be calculated from the frequencies of the high and low frequency portions. In addition, the ideal impedance can be obtained by selecting the value of the capacitor C1. It will be appreciated that such a network consisting of a capacitor and an inductor has a complex impedance. Therefore, with the self-resistance of circuit components and wires, by selecting and adjusting the values of the components of the matching network, the low frequency portion from the output port under low frequency when the low frequency portion is connected to the low frequency RF generator, It is possible that the resulting impedance, when measured by, will be substantially conjugate matched to the impedance as measured from the output port via the return path under low frequency. When the high frequency portion is connected to the high frequency RF generator, the impedance under high frequency measured from the output port to the high frequency portion is substantially conjugate matched to the other impedance under high frequency measured from the output port to the high frequency portion via the return path.

In the RF matching network shown in FIG. 5, the low frequency RF energy is the output of the output port coming through a circuit consisting of capacitor C2 and inductor L. The low frequency RF output can then have two branches or paths that can go, either to the vacuum process chamber or to the high frequency portion. The high frequency portion includes capacitor C2 'and inductor L' (in addition to parasitic capacitance). In this embodiment, the capacitor C2 'and the inductor L' of the high frequency portion are configured for the low frequency RF input so that the impedance of the high frequency portion is much larger than the impedance of the vacuum process chamber. Thus, most of the low frequency RF generator energy is input into the vacuum process chamber. In addition, by selecting an appropriate value for the capacitor C2 ', the energy input to the high frequency portion can be reduced to 2% or less.

In a similar manner, high frequency RF energy reaches the output port through a circuit consisting of capacitor C2 'and inductor L'. The high frequency RF output may then have two branches or paths that can go, either into the vacuum process chamber or into the low frequency portion. The low frequency portion includes parasitic capacitance, capacitor C2, and inductor L, where inductor L and capacitor C2 are connected in series. One terminal of capacitor C1 is connected to capacitor C2 and the other terminal is grounded. With this circuit configuration, by adding the calculated values of the capacitors and inductors, and further adjusting the value of the capacitor, it is possible to realize that the impedance of the low frequency portion for the high frequency RF input is much larger than the impedance of the vacuum process chamber. Thus, most of the high frequency RF generator energy is input into the vacuum process chamber. In addition, by selecting an appropriate value for capacitor C1, the energy input into the low frequency portion can be reduced to 2% or less.

Referring again to FIGS. 1 and 2, process gas is provided from a common source 160. Gas from the common source 160 is distributed to the respective treatment regions from the showerheads 170 and 175, which in this embodiment are dual-zone showerheads. That is, as shown in FIG. 1, the showerhead 170 includes a central region 172 and a peripheral region 176 separated by a seal 174. The gas transfer pipe 171 transfers the gas to the central region 172, while the gas transfer pipe 173 transfers the gas to the peripheral region 176. The gas transfer ratio of the central region to the peripheral region can be controlled by the common source 160. In addition, the components of the gas carried by the pipes 171 and 173 may also be controlled by the common source 160. That is, the pipes 171 and 173 can carry different or identical gases or mixed gases. Complementary arrangements are made for the processing region 115.

Showerheads 170 and 175 also include conductive electrodes embedded to form a ground path for RF power coupled to respective cathodes 120 and 125.

1 also shows a central vacuum pump 180. The vacuum pump 180 exhausts both treatment regions 110 and 115 through the pumping port 182 of the exhaust chamber 184. The use of a single pump 180 simplifies the overall chamber configuration and makes the chamber compact. In addition, a common pumping port helps to equalize the pressure between the two treatment regions 110 and 115. However, this configuration also has some problems as follows in this embodiment.

Although the following description is provided with respect to the processing region 110, it should be understood that the same may be applied to the processing region 115. As shown in FIG. 1, the pumping port 182 is provided between the two processing regions 110 and 115, thus creating an oblique processing path for each processing region. For example, arrow A shows the path from the area close to the pumping port 182, while arrow B shows the path from the portion of the processing area remote from the pumping port 182. As can be appreciated, path B is longer than path A, which leads to a pressure difference in the treatment region 110. To overcome this problem, in this embodiment, micro channel plasma confinement rings 190 and 195 are provided in each processing region. Constraining ring 190 provides isolation between treatment region 110 and pumping port 182 while allowing vacuum pumping from treatment region 110 in a manner that equalizes pressure across treatment region 110. to provide. Ring 190 may be implemented with any of the rings disclosed in US Application Publication No. 2007/0085483, which is incorporated by reference in its entirety.

One embodiment of a plasma confinement ring that can be used with the chamber of FIG. 1 is generally indicated at 70 in FIGS. 3 and 4. Other plasma constraining rings may be used, but to provide a more complete description, the embodiments of FIGS. 3 and 4 will be described in greater detail. As shown in FIGS. 3 and 4, the plasma confinement apparatus is located between the processing region 110 and the exhaust chamber 184. In the embodiment of FIG. 1, the ring 70 is provided such that the top is at approximately the same level as the wafer 130. The plasma constraining ring 70 comprises, in part, an electrically grounded conductive member, which is indicated generally by the reference numeral 71. The electrically grounded member is defined by an outer peripheral edge 72 and an opposite inner peripheral edge 73, which generally surrounds the inner wall 183 of the exhaust chamber 184. In addition, the electrically grounded member 71 has an upper surface 74 and an opposite bottom surface 75. As shown, a plurality of passages 76 are formed in a predetermined pattern in the electrically grounded member 71 and extend between the upper and lower surfaces 74 and 75. The electrically grounded member 71 forms an electric field shield to substantially prevent RF emissions from reaching the pumping port 182. In this way, the plasma cannot reach the pumping port 182. In addition, RF crosstalk between the two processing regions 110 and 155 is prevented.

The plasma confinement ring 70 further includes an electrically insulating layer 80, which is located in a partial cover relationship over or with respect to the top surface 74 of the electrically grounded member 71. As shown in FIG. 4, the electrically insulating layer extends substantially radially inward with respect to the outer peripheral edge 72. The electrically insulating layer comprises a single layer or multiple layers, as shown. Positioned or lying on the electrically insulating layer 80 is an electrically conductive support ring, generally indicated at 90. The support ring includes an outer peripheral edge 91 that is substantially coplanar with respect to the outer peripheral edge 72 of the electrically grounded member, and further includes an inner peripheral edge 92 at regular intervals therefrom. The support ring 90 formed by gathering a plurality of electrically conductive members 95 has a plurality of electrically conductive members 95 arranged at predetermined intervals from each other and electrically insulated from the electrically grounded member 71. The electrically conductive member 95 allows it to be electrically floating from ground during processing. The plurality of electrically conductive members 95 herein define a plurality of passages 99 connected therein in a fluid flow relationship with respect to the plurality of passages 76 defined by the electrically grounded member 71, wherein the plurality of electrically conductive members 95 are defined therein. It is shown as a substantially concentric ring 96 at regular intervals of. Thus, passages 76 and 99 respectively form a fluid passageway such that the process gas employed to form the plasma used in processing region 110 leaves the processing region and proceeds to exhaust port 182. In one form of the invention, the electrically conductive component or member 95 may be made of a doped semiconductor material. In this configuration, the doping of the semiconductor material increases the electrical conductivity of the semiconductor material.

As can be appreciated from the description of FIG. 4, each passage 99 has a length that is longer than the average free stroke length of any charged species that may be present in the plasma formed in the treatment region 110. Thus, as the plasma moves from the treatment region to the exhaust region, all charged species passing through the passage 99 are likely to impinge on a plurality of electrically conductive concentric rings 96, thereby exhausting the charged paper plasma processing apparatus. Inhibit charged species before reaching the area. According to the invention shown in FIGS. 3 and 4, the surface of the electrically conductive member 95, here a plurality of electrically conductive concentric rings 96, is substantially free of etching by plasma generated in the treatment region 110. It may be coated with, or wrapped in, a resistant material. According to one embodiment of the invention, the material coated on the surfaces of the plurality of electrically conductive members 96 comprises Y ₂ O ₃ . This surface coating prevents the electrically conductive member 95 from being etched by the plasma and thereby producing particles. According to another embodiment, the electrically conductive member 96 may include a plate having slotted perforations or holes formed therein rather than utilizing an arrangement of the conductive members 96.

Several alternative embodiments of the restraint ring are also possible. For example, the surfaces of the electrically grounded member 71 and the plurality of electrically conductive rings 96 in contact with the plasma may be anodized to resist etching and form an electrically insulating layer thereon. Will understand. It will be appreciated that anodization is a form of electrolysis that allows protective oxide coatings to form on metals. Anodization can be used for a variety of purposes, including providing a hard coating on the surface of the metal, as well as providing electrical insulation and corrosion resistance to the metal. According to one aspect of the invention, the plurality of electrically conductive members 96, the electrically conductive support ring 90 and the electrically grounded member 71 are formed of aluminum, and the electrically insulating layer 80 is electrically grounded. Aluminum formed by anodizing the surface of the electrically conductive support ring 90 opposite the member 71 or anodizing the surface of the electrically grounded member 71 opposite the electrically conductive support ring 90. Anodization layer. In another form of the invention, all surface areas of these same structures can be anodized. This ensures that the electrically conductive member 95 is electrically floating with respect to ground during processing. According to still another aspect of the present invention, the surface areas of the plurality of electrically conductive rings facing or in contact with the plasma may be first anodized and then coated with Y ₂ O ₃ which is more resistant to etching. In addition to the above, an insulating spacer ring (not shown) may be disposed between the electrically conductive support ring 90 and the underlying electrically grounded member 71, which is electrically grounded by the electrically conductive member 95. Ensure that it is electrically floating against. According to this aspect of the invention, the electrically insulating layer 80 can be replaced by an electrically insulating spacer. The electrically insulating spacer similarly causes the electrically conductive member 95 to be electrically floating from ground.

As can be appreciated, the plasma constraining ring 70 used in the plasma processing region 110 is positioned on the electrically grounded member 71 and the electrically grounded member 71 and is electrically conductive but floating member. (95). In this way, the plasma constraining ring of this embodiment forms a plasma shield and an RF shield. That is, the floating member constitutes a plasma shield that prevents active species from passing through, while the grounded member constitutes an RF shield that prevents RF energy from passing through it. The floating member 95 defines a plurality of passageways 99 in which the pumping of the processing region 110 is operated in a controlled manner. The plurality of passageways 99 are sized to inhibit the charged species and allow the neutral species to pass through. In this way, the confinement ring 70 enables pumping control of the treatment region 110 to provide uniform pressure to the treatment region, prevents reaching the charged paper pumping port 182, and pumping port. Prevents RF coupling to pumping port 182 and prevents RF crosstalk between processing regions 110 and 115 to prevent plasma ignition at 182.

Another form of this embodiment is indicated as an isolation ring 132 in FIG. 2. The isolation ring 132 can move in the vertical direction as indicated by arrow D. FIG. While transporting the wafer into or out of the processing region 110, the ring is moved to an upper position, opening the wafer loading slit 134. Once the wafer is installed over the cathode, the isolation ring is lowered to the position shown in FIG. In this position, the treatment region 110 defined by the isolation ring is symmetrically circular and the loading slit 134 is "hidden" to the plasma so that the plasma only "sees" the circular boundary. That is, in the lower position, each isolation ring defines a peripheral boundary of each treatment area. In addition, the isolation ring in this embodiment is made of an insulator and is T in thickness to isolate the grounded chamber wall from the plasma. That is, the thickness T is calculated to prevent the return path from the plasma via the grounded wall 105. In this way, the RF return path is controlled to flow through the showerhead 170, which acts as an upper electrode in the RF return path.

Isolation ring 132 may also be used for pressure balancing. One example of such a configuration is shown in FIG. 6. The chamber 600 of FIG. 6 is similar to that of FIGS. 1 and 2 and will not be described in detail except for the specific features highlighted in FIG. 6. In particular, FIG. 6 shows one embodiment in which a pressure balancing mechanism is provided between two treatment regions. According to this example, the pressure balancing mechanism is implemented using the isolation ring 632. As shown, a channel 684 is provided in the dividing wall 682. As the isolation ring 632 is moved to the upper position as indicated by arrow D, the channel 684 allows free gas movement between the two treatment regions 610 and 615. In addition, channels 634 and 636 are provided in the isolation ring 632. When the isolation ring is in the lower position as shown in FIG. 6, channels 634 and 636 form a passage with channel 684. In this manner, the pressure between the treatment regions 610 and 615 may be balanced by fluid transfer through the channels 634, 684 and 636.

7 shows another embodiment of the invention in which multiple frequencies are applied to each of the two cathodes. The embodiment of FIG. 7 may be implemented by modifying any of the other embodiments disclosed herein, along with other embodiments that are not described in detail herein but may be inferred from the presented description. The particular embodiment shown in FIG. 7 utilizes the basic embodiment shown in FIG. 1 and, therefore, like elements are designated by like reference numerals, except that they are 700 numbers rather than 100 numbers.

As shown in FIG. 7, each cathode 720, 725 receives three RF frequencies. This is done to improve the control of the etching process by controlling the plasma density and ion energy independently. That is, one or two frequencies can be used to control the plasma ion energy. The frequency for plasma ion energy control should be selected in the lower range, for example, one frequency is selected within the range of 500 KHz to 2 MHz, while the other is set to 13 MHz (more precisely 13.56 MHz). These are generally referred to as bias frequencies. The plasma density can be controlled by higher RF frequencies, for example 27 MHz, 60 MHz, 100 MHz, or 160 MHz, which is referred to as the source frequency. On the other hand, a configuration of a single bias frequency and a dual source frequency may be employed. For example, a single bias frequency can be selected from values of 500 KHz to 2 MHz and 13 MHz. The dual source frequency can then be selected, for example, from 27 MHz, 60 MHz, 100 MHz, or 160 MHz.

In a particular example, one bias frequency 754, 756 is used and set to 2 MHz or 13 MHz. Two source frequencies are used, 751 and 752 for cathode 720 and 758 and 759 for cathode 725. One of each source RF frequency is set to 27 MHz and the other is set to 60 MHz. This configuration provides improved control of plasma species dissociation.

Other features shown in the embodiment of FIG. 7 are switches 763 and 767. Switches 763 and 767 enable switching among various supply frequencies for better control of plasma dissociation. By using switches 763 and 767, any of the above embodiments can also be used to operate the plasma chamber, such that a first period of operation in a first combination of bias and source frequency, and a second combination of bias and source frequency Provide a process comprising a second period of time operating in. For example, the chamber can be operated using a low bias frequency, eg, about 2 MHz in the main etch step. However, to achieve softlanding during over etching, the system can be switched to operate using a higher frequency bias, such as about 13 MHz. On the other hand, the chamber can be operated using a low source frequency, for example about 27 MHz, in the etching step. However, after completion of the etching, the wafer is removed and the chamber can be cleaned using a higher density plasma. Higher density plasmas can be made using higher source frequencies, such as 60 MHz, 100 MHz, or 160 MHz.

8 provides an example of a process using two bias frequencies in accordance with one embodiment of the present invention. This process can be for example the etching of a semiconductor wafer. In step 800, the source RF power supply is activated to ignite the plasma. The source RF power source may have frequencies of 27 MHz, 60 MHz, 100 MHz, 160 MHz, and the like, for example. In step 810, the first bias frequency is activated so that dissociated ions are applied to the chamber to impinge on the wafer during the first processing step (step 820). When the first processing step is complete, the first bias power is deactivated in step 830 and the second bias power is activated in order to proceed to the second processing of step 850 in step 840. In this case, the first bias frequency may be about 2 MHz, for example, and the second bias frequency may be about 13 MHz. In this case, if the bias frequency is 2 MHz, the source frequency is at least 10 times higher. On the other hand, if the bias frequency is 13MHz, the source frequency may be twice or more frequencies. For example, when the bias is 13 MHz, the source can be twice as high, 27 MHz, about 5 times 60 MHz, or even 100 MHz or 160 MHz.

9 provides an example of a process using two source frequencies in accordance with one embodiment of the present invention. This process may be, for example, a process that performs a semiconductor wafer etch and and “in-situ” cleaning process. In step 900, the first source RF power supply is activated to ignite the plasma. The source RF power can be, for example, a frequency of 27 MHz. In step 910, the bias frequency is activated so that dissociated ions are applied to the chamber to impinge on the wafer during the etching process step (step 920). Once the etching process step is complete, the bias power is deactivated in step 930 and the wafer is removed from the chamber in step 935. Next, at step 940, the second source power is activated to proceed to cleaning step 950. In this case, the second source frequency may be 60 MHz, 100 MHz, or 160 MHz, for example.

It will be understood that the processes and techniques described herein are not inherently related to any particular apparatus and may be implemented by any suitable combination of components. In addition, various types of general purpose devices are available in accordance with the description disclosed herein. It may also be proven advantageous to configure specialized devices to perform the procedural steps disclosed herein. The invention has been described in connection with specific embodiments, which are not intended to be limiting and are intended for illustrative purposes. Those skilled in the art will recognize that many other combinations of hardware, software, and firmware will be suitable for the practice of the present invention. For example, the methods and systems described above may be implemented in a wide variety of programming languages or scripts, such as Assembler, C / C ++, Perl, Shell, PHP, Java, and the like.

Although the present invention has been described in connection with specific embodiments, it is not intended to be limiting and is intended for illustrative purposes. Those skilled in the art will recognize that many other combinations of hardware, software, and firmware will be suitable for the practice of the present invention. In addition, from the description and examples of the invention disclosed herein, other implementations of the invention will be apparent to those skilled in the art. Various aspects and / or components of the disclosed embodiments may be used alone or in any combination in the plasma chamber technology. The description and embodiments of the present specification are intended as merely preferred examples, and the spirit and scope of the present invention are defined by the claims.

The following drawings, together with the description of the invention, provide various non-limiting examples of various embodiments of the invention as defined by the claims. DETAILED DESCRIPTION The various aspects and forms of the invention will be clearly understood from the following description, referred to by the description of the invention and the following description of the invention.

The following drawings, which are attached to and constitute a part of the present specification, illustrate embodiments of the present invention, and serve to explain and illustrate the technical idea of the present invention together with the detailed description of the present invention. The drawings are intended to illustrate principal aspects of the preferred embodiments in a schematic manner. The accompanying drawings are not intended to represent all the forms of actual embodiments or the relative dimensions of the illustrated components, nor are they drawn to scale.

1 is a schematic cross-sectional view of a tandem plasma chamber according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view taken along the line C-C of FIG. 1.

3 is a cross-sectional perspective view of an embodiment of the plasma confinement device of the present invention.

4 is a partially enlarged cross-sectional perspective view of the embodiment of the plasma confinement device shown in FIG. 3.

5 is a conceptual diagram of an RF matching network structure of the present invention.

FIG. 6 shows one embodiment in which a pressure equalizing mechanism is provided between two treatment regions.

7 shows another embodiment of the present invention in which multiple frequencies are applied to each of the two cathodes.

8 provides an example of a process using two bias frequencies in accordance with one embodiment of the present invention.

9 provides an example of a process using two source frequencies in accordance with one embodiment of the present invention.

Claims (32)

10. A plasma process chamber having at least two processing regions allowing for the individual or simultaneous processing of at least two wafers, At least two plasma processing regions each comprising a cathode disposed below and an anode mounted on the ceiling, and a chamber body defining an exhaust passage; At least one vacuum pump connected to the exhaust passage; And At least two RF matching circuits respectively coupling at least a first RF frequency and a second RF frequency to one of the cathodes, The first frequency is higher than the second frequency. The method of claim 1, And at least two plasma confinement rings, each disposed around a corresponding cathode, to prevent plasma transfer from a processing region to the exhaust passage. The method of claim 2, Each said plasma confinement ring comprises a plasma shield and an RF shield. The method of claim 3, The plasma shield comprises a conductive but floating member and the RF shield comprises a grounded conductive member. The method of claim 1, And two movable insulating isolating rings, each provided in one processing region, each defining a peripheral boundary of each processing region when in the lower position. The method of claim 5, The chamber body defining a grounded chamber wall for each processing region, each isolation ring having a thickness designed to shield the grounded chamber wall from RF energy. The method of claim 6, Each isolation ring further comprises at least one pressure balancing passage. The method of claim 7, wherein And a separating wall separating each of the two processing regions, the separating wall comprising a pressure balancing channel, the pressure balancing channel being in communication with the pressure balancing passage when the isolation ring is in the lower position. chamber. The method of claim 1, Further comprising a plurality of RF conductors, each coupling energy from one RF matching circuit to the corresponding cathode, each of the RF conductors having the same radial distance to couple the RF energy onto each cathode in the same manner; A plasma process chamber having a plurality of spaced apart branches. The method of claim 9, Each of the RF matching circuits includes a high frequency input, a low frequency input, a combined output, a high frequency matching circuit coupled between the high frequency input and the combined output, and a low frequency matching circuit coupled between the low frequency input and the combined output; And the high frequency matching circuit exhibits high impedance at second and fourth frequencies and the low frequency matching circuit exhibits high impedance at first and third frequencies. The method of claim 10, Wherein the first frequency is selected from 27 MHz, 60 MHz, and 100 MHz. The method of claim 10, And said second frequency is selected within the range of 500 KHz to 2.2 MHz. The method of claim 1, Each of the RF matching circuits further couples a third RF frequency to a corresponding cathode. The method of claim 13, And a plurality of switches, each switch operative to select one of said first, second, and third RF frequencies. In a tandem plasma etch chamber, Defining a first processing region and a second processing region; A partition wall separating the first processing region and the second processing region; An exhaust chamber including a single exhaust port and in fluid communication with said first processing region and said second processing region; A conductive chamber body connected to ground potential; A vacuum pump connected to the exhaust port; A first fixed cathode fixed to the lower portion of the first processing region and including a first chuck supporting the wafer; A first shower head fixed to a ceiling of the first processing region and including a first electrode; A second fixed cathode fixed to the bottom of the second processing region and including a second chuck supporting the wafer; A second shower head fixed to the ceiling of the second processing region and including a second electrode; A common gas source providing process gas to the first showerhead and the second showerhead; A first RF matching circuit for simultaneously coupling at least one low RF frequency and at least one high RF frequency to the first cathode; And A second RF matching circuit for simultaneously connecting at least one low RF frequency and at least one high RF frequency to said second cathode, And said high RF frequency is at least twice as high as said low RF frequency. The method of claim 15, A first plasma confinement ring disposed around the first cathode and preventing plasma transfer from the first processing region to the exhaust chamber; And a second plasma confinement ring disposed around the second cathode and preventing plasma transfer from the second processing region to the exhaust chamber. The method of claim 16, Each of the first and second plasma confinement rings comprises a plasma shield and an RF shield. The method of claim 16, And the plasma shield comprises a conductive but floating member and the RF shield comprises a grounded conductive member. The method of claim 15, A movable first insulating isolation ring provided in said first processing region; And Further comprising a movable second insulating isolation ring provided in said second processing region, And the first and second isolation rings take an upper position during wafer loading and a lower position during wafer processing. The method of claim 19, Each of the first and second isolation rings having a thickness designed to shield the grounded chamber wall from RF energy. The method of claim 20, Each of the first and second isolation rings further comprises at least one pressure balancing passage. The method of claim 21, And the dividing wall comprises a pressure balancing channel, wherein the pressure balancing channel is in communication with the pressure balancing passages of the first and second isolation rings when the first and second isolation rings are in a lower position. The method of claim 15, The low frequency is selected within the range of 500 KHz to 2.2 MHz and the high frequency is selected from 27 MHz, 60 MHz, and 100 MHz. The method of claim 15, A first switch connected to the first RF matching circuit and a second switch connected to the second RF matching circuit, each of the first and second switches being configured from the selection of two low RF frequencies; A tandem plasma etching chamber operable to select a low RF frequency, or to select the high RF frequency from a selection of two high RF frequencies. The method of claim 15, And wherein each of said first and second processing regions is operable independently of each other. In a decoupled reactive ion etch chamber, Define a plurality of processing regions; Having a separating wall comprising a fluid transfer channel for separating the plurality of processing regions from each other and equalizing the pressure between the processing regions; And an exhaust chamber in fluid communication with the processing regions; A conductive chamber body connected to ground potential; At least one vacuum pump connected to the exhaust chamber; A plurality of cathodes each fixed to a lower portion of a corresponding one of said processing regions, said plurality of cathodes comprising a chuck for supporting a wafer; A plurality of showerheads fixed to a corresponding one ceiling of said processing region and comprising electrodes; A common gas source providing process gas to the showerhead; And And a plurality of RF matching circuits each simultaneously connecting at least one low RF frequency and at least one high RF frequency to a corresponding one of the cathodes. The method of claim 26, And a plurality of plasma confinement rings each disposed around a corresponding cathode, the plasma confinement rings for preventing plasma transfer from one processing region to the exhaust chamber. The method of claim 27, Each plasma constraining ring includes a plasma shield and an RF shield. The method of claim 28, And wherein the plasma shield comprises a conductive but floating member, and the RF shield comprises a grounded conductive member. The method of claim 26, A separate reactive ion etch chamber, each provided in one processing region, further comprising a plurality of movable insulating isolating rings each defining a peripheral boundary of each processing region when in the lower position. The method of claim 30, Each isolation ring having a thickness designed to shield the grounded chamber wall from RF energy. The method of claim 31, wherein Each isolation ring further comprises at least one pressure balancing passage in communication with the fluid delivery channel when the isolation ring is in the lower position.

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