CN101043784B - hybrid plasma reactor - Google Patents

Abstract

Provided is a hybrid plasma reactor. The hybrid plasma reactor includes an ICP (Inductively Coupled Plasma) source unit and a bias RF (Radio Frequency) power supply unit. The ICP source unit includes a chamber, an antenna coil unit, and a source power supply unit. The chamber includes a chamber body whose top is opened and a dielectric window covering the opened top of the chamber body. The antenna coil unit is disposed outside of the dielectric window. The source power supply unit supplies a source power to the antenna coil unit. The bias RF power supply unit supplies a bias RF power to a cathode. The cathode is installed within the chamber and mounts a target wafer on its top.

Description

hybrid plasma reactor

technical field

The present invention relates to an apparatus used in a semiconductor manufacturing process, and in particular to a plasma reactor. the

Background technique

Generally, plasma reactors that perform a dry etching process using plasma are classified into a capacitively coupled plasma (CCP) type plasma reactor and an inductively coupled plasma (ICP) depending on a method of generating plasma in a chamber. type plasma reactor. As is known in the art, in a CCP type plasma reactor, the ion flow energy within the plasma chamber increases proportionally as the frequency of the radio frequency (RF) power supplied to the top electrode or cathode decreases. And, in the CCP type plasma reactor, the ion density increases as the frequency of RF power supplied to the upper electrode or the cathode becomes higher. In an ICP type plasma reactor, low ionization conditions and high ionization conditions can be provided within the chamber as the RF power supplied to the antenna coil is increased. The degree of dissociation of the reactant gas is lower in low ionization conditions and higher in high ionization conditions. When an ICP type plasma reactor performs an etching process under respective low ionization conditions and high ionization conditions, a target wafer exhibits physical properties different from each other. More specifically, when an ICP type plasma reactor performs an etching process under low ionization conditions, a target wafer exhibits physical properties similar to when a CCP type plasma reactor performs an etching process. When an ICP type plasma reactor performs an etching process under high ionization conditions, as the frequency of the offset RF power supplied to the cathode becomes lower, an increase in the RF power supplied to the antenna coil results in plasma ions in the chamber A sudden drop in energy. the

As for the dry etching process realized using plasma, there are insulating film (oxide) etching process and polyethylene (poly)/metal etching process. The insulating film etching process is mainly based on the physical etching process. Therefore, an insulating thin film is mainly etched using a narrow-gap CCP type plasma reactor in which multi-frequency RF power is supplied to an upper electrode or a cathode. The advantage of this CCP type plasma reactor is the ability to generate high energy ions using high electric fields. However, CCP type plasma reactors cause process equipment damage due to ion collisions, and cause arcing problems due to the high plasma potential characteristic. Low ionization reduces the efficiency of real-time chamber cleaning (ICC), therefore, the mean time between chamber cleanings (MTBC) is realized to be very short. The CCP type plasma reactor has problems in terms of hardware design and cost required to supply high frequency power to the upper electrode or cathode. the

Unlike the insulating film etching process, the polyethylene/metal etching process, which is generally based on the relative chemical etching method, mainly uses an ICP type plasma reactor. This is because the ICP type plasma reactor can independently control the plasma ion density and energy in the chamber, promote high-density and large-scale plasma generation at low pressure, and sufficiently etch devices with small plasma ion energy, Thereby reducing equipment loss. the

Very important parameters to realize ICP type plasma reactors are damage of dielectric window due to high voltage supplied to antenna coil, high/low plasma ion density and uniformity in a wide area, excess radical concentration control , adjustable ion energy, and wide ion energy distribution. the

However, the ICP-type plasma reactors manufactured so far can generate high-density plasma ions, but cannot control the concentration of excess radicals, cannot control the plasma ion energy, and cannot expand the plasma ion energy distribution. Therefore, the ICP type plasma reactor shows worse process performance than the CCP type plasma reactor although it is more efficient than the CCP type plasma reactor. Therefore, it is difficult for an ICP type plasma reactor to perform a high aspect ratio process while ensuring high photosensitive (PR) selectivity. the

In the case of an ICP type plasma reactor performing a dry etching process, high ionization of a reaction gas and an increase in source power supply cause a sudden decrease in plasma ion energy when low frequency RF power is supplied to a cathode. As a result certain phenomena such as etch stop, chamber matching, low PR selectivity, and narrow process window occur. the

Contents of the invention

An aspect of exemplary embodiments of the present invention is to address at least the problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of an exemplary embodiment of the present invention provides a hybrid plasma reactor for supplying offset RF power mixed with high frequency RF power and low frequency RF power to a cathode and controlling source power supplied to an antenna coil, Therefore, when the low frequency RF power is supplied to the cathode, the sudden decrease of the plasma ion energy due to the increase of the source power is compensated, and the plasma ion density and energy are maintained within the set range. the

According to an aspect of an exemplary embodiment of the present invention, a hybrid plasma reactor is provided. The hybrid plasma reactor includes an ICP (Inductively Coupled Plasma) source unit and an offset RF (Radio Frequency) power supply unit. The ICP source unit includes a chamber, an antenna coil unit, and a source power unit. The chamber includes an open top chamber body and a dielectric window covering the open top of the chamber body. The antenna coil unit is placed outside the dielectric window. The source power unit supplies source power to the antenna coil unit. The offset RF power supply unit provides offset RF power to the cathode. The cathode is mounted within the chamber, and a target wafer is mounted on top of the cathode. When the source power greater than the set power is supplied to the antenna coil unit, the plasma ion density in the chamber is greater than that in the chamber when the source power less than the set power is supplied to the antenna coil unit. plasma ion density. When the source power less than the set power is supplied to the antenna coil unit, the plasma ion energy in the chamber is greater than when the source power greater than the set power is supplied to the antenna coil unit. Plasma ion energy in the chamber. In order to increase the set power and expand the adjustable range of the source power supply, the offset RF power supply unit provides offset RF power mixed with high-frequency RF power and low-frequency RF power to the cathode, so as to The power of the source power supply of the antenna coil unit increases to more than the set power to compensate for the sudden decrease in the plasma ion energy in the chamber, or thereby maintain the plasma ion density and energy in the chamber at the set value within a certain range. the

According to another aspect of example embodiments of the present invention, a hybrid plasma reactor is provided. The hybrid plasma reactor includes an ICP source unit and a high frequency RF power supply unit. The ICP source unit includes a chamber, an antenna coil unit, and a source power unit. The chamber includes an open top chamber body and a dielectric window covering the open top of the chamber body. The antenna coil unit is placed outside the dielectric window. The source power unit supplies source power to the antenna coil unit. The high frequency RF power supply unit provides high frequency RF power to the cathode. The cathode is mounted within the chamber, and a target wafer is mounted on top of the cathode. A low-frequency RF power supply unit is connected to the cathode in parallel to the high-frequency RF power supply unit, and supplies low-frequency RF power to the cathode. When the source power greater than the set power is supplied to the antenna coil unit, the plasma ion density in the chamber is greater than that in the chamber when the source power less than the set power is supplied to the antenna coil unit. plasma ion density. When the source power less than the set power is supplied to the antenna coil unit, the plasma ion energy in the chamber is greater than when the source power greater than the set power is supplied to the antenna coil unit. Plasma ion energy in the chamber. In order to increase the set power and expand the adjustable range of the source power supply, the high-frequency RF power supply unit and the low-frequency RF power supply unit work together and provide offset RF power mixed with high-frequency RF power and low-frequency RF power to the cathode, thereby compensating for a sudden drop in plasma ion energy in the chamber that occurs when the source power supplied to the antenna coil unit is increased above the set power, or thereby turning the chamber The plasma ion density and energy are kept within the set range.

According to yet another aspect of example embodiments of the present invention, a hybrid plasma reactor is provided. The hybrid plasma reactor includes an ICP source unit, a high frequency RF power supply unit, a low frequency RF power supply unit, and a source power switching unit. The ICP source unit includes a chamber, an antenna coil unit, and a source power unit. The chamber includes an open top chamber body and a dielectric window covering the open top of the chamber body. The antenna coil unit is placed outside the dielectric window. The source power unit supplies source power to the antenna coil unit. The high frequency RF power supply unit provides high frequency RF power to the cathode. The cathode is mounted within the chamber and a target wafer is mounted on top of the cathode. A low-frequency RF power supply unit is connected to the cathode in parallel to the high-frequency RF power supply unit, and supplies low-frequency RF power to the cathode. The source power switching unit is connected to the cathode in parallel with the high frequency RF power supply unit. The source power switching unit is switched on to selectively connect the cathode to ground through the source power switching unit so that high frequency RF power generated from the source power unit is selectively supplied to the cathode. the

When the cathode is connected to the ground through the source power switching unit, a closed loop is formed, and the closed loop includes the source power unit, the antenna coil unit, the cathode, the source power switching unit and ground. The source power is RF power having a frequency higher than the high frequency RF power frequency, RF power having a frequency lower than the low frequency RF power frequency, and the low frequency RF power frequency and the high frequency RF power frequency any one of the frequencies in between the RF power. the

When the source power greater than the set power is supplied to the antenna coil unit, the plasma ion density in the chamber is greater than that in the chamber when the source power less than the set power is supplied to the antenna coil unit. plasma ion density. When the source power less than the set power is supplied to the antenna coil unit, the plasma ion energy in the chamber is greater than when the source power greater than the set power is supplied to the antenna coil unit. Plasma ion energy in the chamber. the

In order to increase the set power and expand the adjustable range of the source power supply, the high frequency RF power supply unit, the low frequency RF power supply unit and the source power switching unit work together and provide The offset RF power obtained by mixing the low-frequency RF power with the source power is supplied to the cathode, thereby affecting the inside of the chamber that occurs when the source power supplied to the antenna coil unit is increased above the set power. to compensate for the sudden decrease in plasma ion energy, or thereby maintain the plasma ion density and energy in the chamber within a set range. the

Description of drawings

In conjunction with the accompanying drawings to help understand, the above-mentioned and other objects, features and advantages of the present invention can be more clearly understood through the following detailed description in conjunction with the accompanying drawings, wherein:

Fig. 1 shows the construction of the plasma reactor according to the first exemplary embodiment of the present invention;

Fig. 2 shows the sectional view of the antenna coil unit shown in Fig. 1, and the distribution of the magnetic field generated around the antenna coil unit when source power is supplied to the antenna coil unit;

FIG. 3 is a diagram showing the dependence on each radius (R) of the primary antenna coil group and the secondary antenna coil group contained in the antenna coil unit shown in FIG. 2 and the length between the primary antenna coil group and the secondary antenna coil group ( Graphical representation of the magnetic field strength of L);

Figure 4 is a flow chart showing the etching procedure achieved by the plasma reactor shown in Figure 1;

Fig. 5 has shown the construction according to the plasma reactor of the second exemplary embodiment of the present invention;

Figure 6 is a flow chart showing the etching procedure achieved by the plasma reactor shown in Figure 5;

Fig. 7 shows the construction of the plasma reactor according to the third exemplary embodiment of the present invention;

Figure 8 is a flow chart showing the etching procedure achieved by the plasma reactor shown in Figure 7;

Figure 9 is a graph showing the plasma ion density characteristics dependent on the source power increase;

10 is a graph showing the self-offset variation (-VDC) formed in the cathode relative to the source supply power variation when an offset RF power of 2 MHz is provided to the cathode of a plasma reactor according to the present invention;

11 is a graph showing the self-offset variation (-VDC) formed in the cathode relative to the source power supply power variation when an offset RF power of 12.56 MHz is provided to the cathode of a plasma reactor according to the present invention;

12 is a graph showing the self-offset variation (-VDC) formed in the cathode relative to the source power supply power variation when an offset RF power of 27.12 MHz is provided to the cathode of a plasma reactor in accordance with the present invention;

13 is a graph showing the self-offset variation (-VDC) formed in the cathode relative to the source power in the case of providing single frequency offset RF power and mixed frequency offset RF power to the cathode of the plasma reactor, respectively, according to the present invention. Graphical representation of power variation;

14 is a graph showing the change in etching rate relative to the change in the frequency mixing ratio of the offset RF power supplied to the cathode when a source power supply power of 600W is provided to the antenna coil unit of the plasma reactor according to the present invention; and

15 is a graph showing a change in etching rate with respect to a change in frequency mixing ratio of offset RF power supplied to a cathode when a source power supply of 1500 W is supplied to an antenna coil unit of a plasma reactor according to the present invention. the

Throughout the drawings, the same drawing reference numbers represent the same elements, features, and structures. the

Detailed ways

Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. In the following description, detailed descriptions of well-known functions and constructions incorporated herein are omitted for simplicity. the

The present invention provides plasma properties (such as tunable plasma ion density, tunable ion energy distribution, tunable ion energy, tunable radicals, and low Ion-depleting plasma) hybrid type plasma generation apparatus and method. These plasma properties can be controlled using a multi-antenna coil structure, a pillar type dielectric window, an inductively coupled plasma (ICP) source unit provided above the chamber, and a hybrid frequency offset provided to the cathode. the

FIG. 1 shows the configuration of a plasma reactor according to a first exemplary embodiment of the present invention. Referring to FIG. 1 , a plasma reactor includes an inductively coupled plasma (ICP) source unit 1 , and an offset RF power unit including a low frequency radio frequency (RF) power unit 20 and a high frequency RF power unit 30 . The ICP source unit 1 includes a chamber 5 , an antenna coil unit 7 , and a source power unit 10 . The chamber 5 includes a chamber body 13 , and a pillar type dielectric window 11 . The chamber main body 13 is open at its top. A dielectric window 11 covers the open top of the chamber body 13 . The antenna coil unit 7 includes a primary antenna coil group 21 and a secondary antenna coil group 23 . The primary antenna coil group 21 is disposed outside the dielectric window 11 at an upper portion around the dielectric window 11 . The secondary antenna coil group 23 is disposed outside the dielectric window 11 at a lower portion around the dielectric window 11 . The shielding part 3 is attached to the upper portion of the peripheral side wall of the chamber main body 13, surrounds the dielectric window 11 and the antenna coil unit 7 to shield the dielectric window 11 and the antenna coil unit 7 from the outside. the

The dielectric window 11 has a gas injection port 31 at its top. A gas injection system (not shown) injects reaction gas into the chamber 5 through the gas injection port 31 . A cathode component support 15 is disposed within the chamber 5 . The cathode component support 15 is physically fixed to the chamber body 13 and is electrically grounded. The cathode 17 is placed on the cathode member support 15 . An insulator 19 is interposed between the cathode part support 15 and the cathode 17 . The insulator 19 electrically insulates between the cathode part support 15 and the cathode 17 . A wafer (W) is mounted on the cathode 17 as a processing target. More specifically, the wafer (W) is fixed using a ceramic electrostatic chuck (CESC) provided on the cathode 17 . the

The source power supply unit 10 supplies respective source power supplies to the primary antenna coil group 21 and the secondary antenna coil group 23 . The source power supply unit 10 includes a source impedance matching circuit 22 for source impedance matching, and a source high frequency generator 26 . A source impedance matching circuit 22 connects the primary antenna coil set 21 and the secondary antenna coil set 23 with a source high frequency generator 26 . The source high frequency generator 26 is connected to ground. When the source power supply unit 10 supplies source power to the primary antenna coil group 21 and the secondary antenna coil group 23 , a magnetic field is generated near the primary antenna coil group 21 and the secondary antenna coil group 23 . Accordingly, an RF electric field is induced within the chamber 5 . the

The low-frequency RF power supply unit 20 is an offset RF power supply unit that supplies low-frequency RF power to the cathode 17 . The low-frequency RF power supply unit 20 includes an offset impedance matching circuit/low-pass filter (LF matching/LPF) 24 and an offset low-frequency generator 27 . LF Matching/LPF 24 matches impedance and selectively passes only low frequency RF power. Offset low frequency generator 27 generates low frequency RF power. the

The high-frequency RF power supply unit 30 includes an offset impedance matching circuit/high-pass filter (HF matching/HPF) 25 and an offset high-frequency generator 28 . HF Matching/HPF 25 matches impedance and selectively passes only high frequency RF power. Offset high frequency generator 28 generates high frequency RF power. The offset RF power is a mixture of low frequency RF power and high frequency RF power, and is supplied to the cathode 17 when the low frequency RF power supply unit 20 and the high frequency RF power supply unit 30 work together. the

When the source power supply power greater than the set power (hereinafter referred to as "turning point power") is provided to the antenna coil unit 7, the plasma ion density in the chamber 5 is much greater than when the source power supply power less than the set power is provided to the antenna Coil unit 7 is the ion density in chamber 5 . The turning point power is the criterion for dividing the low ionization region and the high ionization region. Referring to FIG. 9, the degree of ionization of the reaction gas when the source power supply power greater than the turning point power is supplied to the antenna coil unit 7 is much greater than the ionization of the reaction gas when the source power supply power less than the turning point power is supplied to the antenna coil unit 7. degree. For example, in a plasma reactor processing a wafer having a diameter of 200mm, the breakpoint power may be set in the range of approximately 500W to 700W. The breakpoint power can be larger or smaller depending on the size, type and process conditions of the plasma reactor. the

When the source power supply power less than the set power is provided to the antenna coil unit 7, the plasma ion energy in the chamber 5 is much greater than the ions in the chamber 5 when the source power supply power greater than the set power is provided to the antenna coil unit 7 energy. When the offset RF power supply unit including the low frequency RF power supply unit 20 and the high frequency RF power supply unit 30 supplies offset RF power mixed with low frequency RF power and high frequency RF power to the cathode 17, the set power can be increased. Therefore, the adjustable range of source power in the low ionization region can be further expanded. For example, when only low-frequency RF power is supplied to the cathode 17 and a source power greater than a set power is supplied to the antenna coil unit 7, a phenomenon in which plasma ion energy in the chamber 5 suddenly decreases occurs. Also, when only high-frequency RF power is supplied to the cathode 17, the plasma ion energy in the chamber 5 is reduced to such an extent that the etching process cannot be normally performed despite increasing the power of the source power. However, when the offset RF power mixed with the low frequency RF power and the high frequency RF power is supplied to the cathode 17, the sudden drop of the plasma ion energy in the chamber 5 can be compensated, and the plasma ion energy can be maintained at the set Within the range, the etching process can be performed normally. the

According to the present invention, the ICP plasma source unit 1 includes an antenna coil unit 7 . As shown in FIGS. 2 and 3 , the antenna coil unit 7 provides uniform magnetic field properties and plasma properties as shown in FIG. 9 . This allows selective use of low and high ionization regions, as well as uniform ion density as described later. the

The cylindrical dielectric window 11 ensures a constant distance between the bulk plasma and the ceramic electrostatic chuck (CESC) (not shown) on the cathode 17 to place the wafer as process target, thereby supporting independent control Plasma ion density and energy. Thus, the pillar dielectric window 11 minimizes physical losses while supporting efficient etch process objectives. the

The antenna coil unit 7 is arranged outside the cylindrical dielectric window 11 . The pillar dielectric window 11 has a top flat surface structure. A gas injection system is provided at a gas injection port 31 provided in the dielectric window 11 . The gas injection system effectively exhausts the etching by-products generated during etching through the exhaust holes. As a result, the reactive gas can have a constant residence time over the entire surface of the processing target, guaranteeing a wide range of processing windows. Also, since the monitoring system can be installed in the space above the dielectric window 11, the hardware design can be flexible. the

As shown in FIG. 2 , the antenna coil unit 7 includes a primary antenna coil group 21 and a secondary antenna coil group 23 . Each of the primary antenna coil group 21 and the secondary antenna coil group 23 has a plurality of antenna coils connected in parallel. The secondary antenna coil group 23 is positioned to maintain a distance of the coil radius (R) from the primary antenna coil group 21 or smaller or larger than the coil radius (R). When the length (L) between the two antenna coil groups 21 and 23 is controlled, the strength of the magnetic field generated in the chamber 5 can be properly controlled. This provides very flexible chamber design for ion density uniformity/intensity and uniform etch rate. Fig. 3 is the magnetic field generated in the chamber 5 when the length (L) between the antenna coil windings 21 and 23 is less than the coil radius (R), when it is equal to the coil radius (R) and when it is greater than the coil radius (R) Graphical representation of the distribution of intensities. As shown in FIG. 3, the magnetic field strength increases when the length (L) is equal to or smaller than the radius (R). When the antenna coil unit 7 satisfies the above conditions and the respective antenna coil windings 21 and 23 are identical to each other in the current direction, a magnetic field with better uniformity and greater strength than conventional solenoid type antenna coils can be generated. This makes it possible to achieve a uniform and very high plasma ion density within the chamber 5 . the

The primary antenna coil group 21 and the secondary antenna coil group 23 each composed of a plurality of coils have a low impedance value. Therefore, a relatively small source supply voltage is dissipated and supplied to multiple coils. This reduces sputtering (ie low sputtering effect) occurring in the chamber 5 and minimizes damage and contamination of the dielectric window 11 by sputtering. the

It is possible to generate and maintain a plasma at low RF power below 20W. When offset RF power mixed with high-frequency and low-frequency RF power is supplied to the cathode 17, the power supply (i.e., turning point) is set as a criterion for dividing the low-ionization region and the high-ionization region, which point is shown in FIG. 9 from point (P1) moves to point (P2). Due to this movement, low-ionization and high-ionization regions can be secured in a relatively wide range, and flexibility in the insulating film etching process can be secured. In other words, the radical concentration can be controlled by controlling the high ionization properties of the ICP type plasma reactor. Enables low-loss and high-efficiency real-time chamber cleaning (ICC), maximizing mean time between chamber cleanings (MTBC) as high plasma can be achieved at constant RF power (approximately 500W to 700W or greater) Bulk ion density and high ionization conditions. Also, an effective solution to the process equipment damage problem of chronic chamber arcing and capacitively coupled plasma (CCP) type plasma reactors can be provided. the

FIG. 4 is a flowchart showing an etching process performed by the plasma reactor shown in FIG. 1. Referring to FIG. the

Referring to FIG. 4 , when the plasma reactor performs dry etching, a wafer (W) as a processing target is fixed by a CESC (not shown) provided on the cathode 17 . The reaction gas is supplied into the chamber 5 through the gas injection port 31 . A vacuum pump (not shown) and a pressure control unit (not shown) maintain the pressure in the chamber 5 at the working pressure. the

In terms of physics/chemistry, plasma generated by the ICP plasma source unit 1 can obtain two modes: CCP mode and ICP mode. As shown in Fig. 9, as the ICP source power increases, the specific plasma ion density does not increase significantly in the low ionization region (CCP mode), while ionization occurs suddenly in the high ionization region (ICP mode). the

More specifically, no sudden ionization occurs below a constant RF source power (ie, breakpoint power), and the plasma reactor exhibits CCP properties. Sudden ionization occurs above a constant RF source supply power, and the plasma reactor exhibits the intrinsic properties of ICP. When the pressure in the chamber 5 reaches the pressure required by the process, the plasma reactor can selectively work in any one of the CCP mode and the ICP mode depending on the process characteristics of the etching mode. the

When the etch process is performed in the low ionization region, the source power is set below the breakpoint power. When the etch process is performed in a high ionization region, the source power is set above the breakpoint power. Once the source power setting is completed, the source power unit 10, the low frequency RF power unit 20, and the high frequency RF power unit 30 are turned on. Therefore, the source power unit 10 supplies constant RF power (ie, source power) to the antenna coil unit 7 while forming plasma in the chamber 5 . Low frequency/high frequency RF power is mixed and supplied to cathode 17 . the

In other words, the upper ICP plasma source unit 1 generates plasma suitable for process characteristics, and at the same time supplies high frequency/low frequency RF power to cathode 17 in a mixed frequency manner suitable for process characteristics, thereby realizing desired processes. Also, the dip in ion energy intensity/ion density/radical concentration can be controlled by properly controlling the ICP source power and low/high frequency RF power supplied to the cathode in low and high ionization regions. Therefore, a high etch rate, high photosensitive (PR) selectivity, and a wide process window can be secured. the

During the etching process, the etching by-products are discharged out of the chamber 5 through the discharge system, and part of them are deposited on the inner wall of the chamber 5 . The etching by-products deposited on the inner wall of the chamber 5 change process characteristics and at the same time act as impurities, causing serious contamination problems of processed objects, thereby reducing quality and productivity. In order to solve this problem, ICC using plasma is implemented for a plasma reactor. the

When the plasma reactor is in the ICC cleaning mode, it performs a wafer-less high-density dry cleaning recipe using only the ICP source power, ie, RF power from the source power unit 10 . More specifically, when the plasma reactor works in the ICC cleaning mode, the source power supply unit 10 provides source power to the antenna coil unit 7, and offsets the RF power supply units (i.e., the low frequency RF power supply unit 20 and the high frequency RF power supply unit 30) Stop supplying offset RF power to cathode 17. Thus, the plasma reactor performs an ICC process using high-density plasma without a target wafer (W) mounted on the cathode 17 . the

Fig. 5 shows the configuration of a plasma reactor according to a second embodiment of the present invention. the

Referring to FIG. 5 , the configuration and detailed operation of the plasma reactor are described based on several differences because they are almost the same as the plasma reactor according to the first embodiment of the present invention. One difference is that the RF power supply unit 50 generates only one of high frequency RF power and low frequency RF power, connected to the cathode 17 . In other words, a high-frequency RF power supply unit or a low-frequency RF power supply unit is connected to the cathode 17 . Another difference is that the source power switching unit 42 is connected to the cathode 17 in parallel with the RF power unit 50 . The source power switching unit 42 supports the cathode 17 to be selectively connected to ground through the source power switching unit 42 so that high frequency or low frequency RF power generated through the source power unit 40 is selectively supplied to the cathode 17 . When the cathode 17 is connected to the ground through the source power switching unit 42, a closed loop including the source power unit 40, the antenna coil unit 7, the cathode 17, the source power switching unit 42 and the ground is formed. The source power switching unit 42 includes a source power filter 37 and a switch 39 . The source power filter 37 filters the source power received from the antenna coil unit 7 through the cathode 17, whereby signals having other frequencies than the source power frequency are excluded from the source power. A switch 39 electrically connects the source power filter 37 to ground, or disconnects it from ground. When the cathode 17 is connected to ground through the source power switching unit 42 and the offset RF power supply unit 50 and the source power supply unit 40 operate, offset RF power in which high frequency RF power and low frequency RF power are mixed is supplied to the cathode 17 . Therefore, the offset RF power supply unit 50 including a low frequency or high frequency RF power supply unit and the source power switching unit 42 supply offset RF power to the cathode 17 .

In the case where the offset RF power supply unit 50 includes a low-frequency RF power supply unit and supplies low-frequency RF power to the cathode 17, the source power supply unit 40 includes a high-frequency RF power supply unit and selectively supplies high-frequency RF power to the cathode 17 through the source power switching unit 42. Cathode 17. the

In the case where the offset RF power supply unit 50 includes a high-frequency RF power supply unit and supplies high-frequency RF power to the cathode 17, the source power supply unit 40 includes a low-frequency RF power supply unit and selectively supplies low-frequency RF power to the cathode 17 through the source power switching unit 42. Cathode 17. the

The source power filter 37 is tuned to the frequency of the source power generated by the source power unit 40 . the

FIG. 6 is a flowchart showing an etching procedure performed by the plasma reactor shown in FIG. 5 . Referring to FIG. 6, when the pressure in the chamber 5 reaches the required pressure of the process, the plasma reactor can depend on the process characteristics of the etching mode, in a similar manner to the plasma reactor according to the first exemplary embodiment of the present invention, Selectively work in any one of CCP mode and ICP mode. the

When the etching process is performed in the low ionization region, the source power supplied to the antenna coil unit 7 is set below the break point power. When the etching process is performed in a high ionization region, the source power supplied to the antenna coil unit 7 is set above the breakpoint power. Once the source power setting is completed, the source power unit 40, the source power switching unit 42, and the offset RF power unit 50 are turned on. Therefore, when the RF power unit 50 provides high frequency or low frequency offset RF power to the cathode 17 , the source power unit 40 provides source power to the cathode 17 through the antenna coil unit 7 . At this time, the cathode 17 is connected to ground through the source power switching unit 42 . the

When the plasma reactor is in the etching mode, the source power switching unit 42 is switched on and performs an etching process. When the plasma reactor is in the ICC cleaning mode, the source power switching unit 42 is switched off and the source power is supplied to the antenna coil unit 7 only. The plasma reactor according to the second exemplary embodiment of the present invention provides the advantages of reducing the cost and size of the equipment because it can obtain the performance corresponding to the plasma reactor according to the first exemplary embodiment of the present invention while passing two RF Power generators 33 and 35 and two impedance matching circuits/filters 29 and 31 replace three RF generators and three impedance matching circuits/filters. the

The inflection point power is greater than that of the first exemplary embodiment because it supports ICP source power being dually supplied to the antenna coil unit 7 and the cathode 17 of the ICP source unit 1 . the

Fig. 7 shows the configuration of a plasma reactor according to a third exemplary embodiment of the present invention. Referring to FIG. 7, the plasma reactor has a structure similar to the combination of the plasma reactors according to the first and second exemplary embodiments of the present invention. The plasma reactor is similar to the plasma reactor according to the first exemplary embodiment of the present invention in that the offset RF power supply unit includes a low frequency RF power supply unit 20 and a high frequency RF power supply unit 30 . This plasma reactor is similar to the plasma reactor according to the second exemplary embodiment of the present invention in that it further includes a source power switching unit 42 to selectively supply source power to the cathode 17 . the

More specifically, the low frequency RF power supply unit 20 and the high frequency RF power supply unit 30 are electrically connected to the cathode 17 in parallel so that low frequency/high frequency RF power is mixed and supplied to the cathode 17 . The source power switching unit 42 is configured to selectively supply source power to the cathode 17. the

In the case where the low-frequency RF power supply unit 20 and the high-frequency RF power supply unit 30 included in the offset RF power supply unit respectively supply low-frequency RF power and high-frequency RF power to the cathode 17, the source power supply unit 10 can pass through the source power supply switching unit 42 Low frequency RF power, which is lower than the low frequency RF power supplied to the cathode 17, is selectively supplied. the

In the case where the low-frequency RF power supply unit 20 and the high-frequency RF power supply unit 30 included in the offset RF power supply unit supply low-frequency RF power and high-frequency RF power to the cathode 17, respectively, the source power supply unit 10 can use the source power supply switching unit 42 Low frequency RF power is selectively supplied which is greater than the low frequency RF power supplied to the cathode 17 and lower than the high frequency RF power supplied to the cathode 17 . the

In the case where the low-frequency RF power supply unit 20 and the high-frequency RF power supply unit 30 included in the offset RF power supply unit supply low-frequency RF power and high-frequency RF power to the cathode 17, respectively, the source power supply unit 10 can use the source power supply switching unit 42 High-frequency RF power that is greater than the high-frequency RF power supplied to the cathode 17 is selectively supplied. the

FIG. 8 is a flowchart showing an etching procedure performed by the plasma reactor shown in FIG. 7. Referring to FIG. the

Referring to FIG. 8, when the pressure in the chamber 5 reaches the required pressure of the process, the plasma reactor can depend on the process characteristics of the etching mode, in a similar manner to the plasma reactor according to the first exemplary embodiment of the present invention, Selectively work in any one of CCP mode and ICP mode. the

When the etching process is performed in the low ionization region, the source power supplied to the antenna coil unit 7 is set below the break point power. When the etching process is performed in a high ionization region, the source power supplied to the antenna coil unit 7 is set above the breakpoint power. Once the source power setting is completed, the source power unit 10 , the low frequency RF power unit 20 and the high frequency RF power unit 30 and the source power switching unit 42 are turned on. Therefore, the low frequency RF power supply unit 20 and the high frequency RF power supply unit 30 supply mixed low frequency/high frequency RF power to the cathode 17 , and the source power supply unit 40 supplies source power to the cathode 17 through the antenna coil unit 17 . At this time, the cathode 17 is connected to ground through the source power switching unit 42 . the

When the plasma reactor is in the etching mode, the source power switching unit 42 is switched on and performs an etching process. When the plasma reactor is in the ICC cleaning mode, a waferless high-density ICC process is performed in a state where the source power switching unit 42 is switched off and the source power is supplied to the antenna coil unit 7 only. The plasma reactor according to the third exemplary embodiment of the present invention is provided for the purpose of expanding large-scale wafers (300mm, 450mm). This plasma reactor can reduce cost and equipment size because it replaces four RF power generators and four impedance matching circuit/filter. the

This inflection point power is greater than that in the first exemplary embodiment because it supports ICP source power being doubly supplied to the antenna coil unit 7 and the cathode 17 of the ICP source unit 1 . the

A graphical representation of the ICP attributes is shown in FIG. 9 to describe the operation of the present invention in detail. Referring to Figure 9, low ionization regions and high ionization regions are provided. As the power of the RF source power supplied to the antenna coil unit 7 is increased, the reaction gas is not suddenly ionized in the low ionization region, and is suddenly ionized in the high ionization region. More specifically, the plasma reactor exhibits CCP properties without sudden ionization below constant RF source power. And the plasma reactor exhibits ICP intrinsic properties in the case of sudden ionization above a constant RF source supply power. the

In addition to the ICP source power, offset power should be supplied to the cathode 17 to process the wafer placed on the cathode 17 . In the case where the bias power with mutually different frequencies (low frequency/medium frequency/high frequency) and the bias power with mixed frequency are respectively supplied to the cathode 17, two properties of the ICP plasma that determine the low ionization region and The properties of the self-deviation (-VDC) of ion energies in regions of high ionization were compared and predicted whether any processing results were obtained in each case. Thus, it can be understood why an insulating film etching apparatus, which is one type of etching apparatus using a conventional ICP type plasma reactor, cannot provide good results, and why many systems are withdrawn from production lines. the

10 is a graph showing the self-offset variation (-VDC) formed in the cathode versus the source supply power variation when 2 MHz offset RF power is supplied to the cathode of the plasma reactor according to the present invention. 11 is a graph showing the self-offset variation (-VDC) formed in the cathode relative to the source supply power variation when an offset RF power of 12.56 MHz is provided to the cathode of a plasma reactor in accordance with the present invention. 12 is a graph showing the self-offset variation (-VDC) developed in the cathode versus the source supply power variation when 27.12 MHz offset RF power is supplied to the cathode of a plasma reactor in accordance with the present invention. the

The graphs of FIGS. 10-12 represent values measured under process conditions in which the reaction gas CF is injected into the chamber ₅ at a rate of 150 standard cubic centimeters per minute (SCCM) and the chamber 5 has an internal pressure of approximately 50 millitorr. .

low ionization area

In the region below constant ICP source RF power (approximately 500W to 700W) in Figure 9, the ion density does not increase abruptly with increasing RF power. In this region, no sudden ionization occurs. the

The self-bias (-VDC) property, which determines the plasma ion energy, can be varied in dependence on the low frequency 2.0MHz, medium frequency 12.56MHz, and high frequency 27.12MHz of bias power supplied to the cathode to process wafers placed on the cathode. These properties are shown in Figures 10-12. From these graphs, it can be understood that self-offset (-VDC) increases with increasing source power in the region below constant ICP source power (approximately 500W to 700W). Also, the plasma ion energy increases as the frequency of the offset power supplied to the cathode decreases. Plasma ion energy decreases with increasing frequency of bias power supplied to the cathode. the

13 is a graph showing the self-offset variation (-VDC) formed in the cathode relative to the source power in the case of providing single frequency offset RF power and mixed frequency offset RF power to the cathode of the plasma reactor, respectively, according to the present invention. Graphical representation of power changes. In FIG. 13, the "◆" marked line represents the change in self-bias (-VDC) (corresponding to plasma ion energy) when low-frequency offset RF power is supplied to the cathode. The "▲" marked line indicates the change in self-offset (-VDC) when high-frequency offset RF power is supplied to the cathode. The "X" marked line represents the change in self-offset (-VDC) when an offset RF power that mixes low frequency and high frequency RF power is supplied to the cathode. As can be understood by the various lines, when mixed frequency offset RF power is supplied to the cathode, the ion energy is approximately equal to the average of the energy values when low frequency/high frequency RF power is supplied to the cathode. the

In the illustration of Fig. 13, the measured values are not shown, but the plasma ion density may have larger values depending on the magnitude of the frequency and the amount of offset power in the low ionization region. the

Therefore, the reaction gas is not suddenly ionized as the power of the source power is increased in the low ionization region. Since ion energy intensity and ion density are relatively dependent on frequency and amount of offset power, concentration control of excess groups is possible. And a wide process window and stable process can be obtained. the

In FIG. 14 showing the etching rate of the insulating film (Si0 ₂ ), when the same amount of offset power is supplied, the etching rate is highest at the mixing frequency. This is due to high ion energy due to low frequency and high ion density due to high frequency supplied to the cathode. Under this condition, etch rate and etch rate non-uniformity are more dependent on offset power.

high ionization area

In the region of Figure 9 above constant ICP source RF power (approximately 500W to 700W), the ion density increases abruptly with increasing RF power. In this region, ionization occurs suddenly. the

Figures 10 to 12 are graphs showing the self-offset of plasma ion energy (- An illustration of the properties of VDC). From these illustrations, it can be understood that the self-offset (-VDC) varies greatly with increasing source power in the region above constant ICP source power (approximately 500W to 700W). In other words, it can be understood that the self-offset (-VDC) suddenly becomes smaller as the power of the source power increases in this region. And, as the frequency gets smaller, the self-offset suddenly becomes smaller. As the frequency becomes larger, the self-offset becomes progressively smaller. the

Figure 13 is a graph showing the relationship between self-bias (-VDC), ie ion energy and single and mixed frequencies. The ion energy intensity at the mixed frequency is approximately equal to the average of the ion energy intensity at low/high frequencies. The sudden drop in ion energy at the low frequency of 2.0 MHz can be largely smoothed out by adding the high frequency of 27.12 MHz. the

Here, the measured value is not shown, but the plasma ion density may have a larger value depending on the magnitude of the frequency and the amount of offset power in the high ionization region. the

Therefore, as the power of the source power increases in the high ionization region, the reaction gas is suddenly ionized. A high frequency is added and applied to ensure a stable and wide process window because the ion energy intensity changes abruptly as the frequency supplied to the cathode becomes lower. the

In FIG. 15 showing the etching rate of the insulating film (SiO ₂ ), when the same amount of offset power is applied, the etching rate is almost the same at low frequency and mixed frequency. It can be appreciated that the change in etch rate in regions of high ionization is much different than the change in etch rate in regions of low ionization. This is because the ion density of the plasma reactor is more dependent on the power of the ICP source. The sudden decrease in ion energy intensity/ion density/radical concentration can be controlled by proper control of ICP source power and low/high frequency RF power supplied to the cathode in the high ionization region. Therefore, a high etch rate, high selectivity, and a wide process window can be guaranteed.

As described above, the present invention provides a hybrid plasma reactor for simultaneous capacitive and inductive coupling functions, thereby doubling process performance and productivity. More specifically, the present invention can improve process performance by properly coordinating ICP source power with high ion density properties and low ion energy properties by mixing frequency offset RF power, such as tunable ion density, tunable ion energy, and ion Energy distribution, group concentration control, and increased productivity, such as dramatic improvements in MTBC. the

According to the present invention, when an ICP type reactor implements a dry etching process, a high frequency is additionally added to compensate for the sudden drop in ion energy intensity that occurs with increasing ICP source power in high ionization regions when low frequencies are applied to the cathode. Thus, the present invention can provide solutions to the drawbacks of etch stop, chamber matching, low PR selectivity, and narrow process window of ICP type reactors. The present invention can add high frequency to low frequency in the low ionization region, thereby ensuring high ion energy and ion density, and increasing the etching speed. the

The present invention can maximize the advantages of ICP type reactors, such as high efficiency, low ion loss, and decoupled effect, and can effectively perform waferless ICC compared with CCP type reactors. The present invention can provide a solution to the problem of chronic arcing that occurs in CCP type plasma reactors. the

The plasma reactor of the present invention can suppress excessive ionization of the reactant gas, maintain a high plasma ion density, and compensate for sudden drops in ion energy intensity above constant ICP source power when low frequencies are supplied to the cathode. the

Although the present invention has been shown and described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. the

Claims (9)

1. hybrid plasma reactor comprises:

The ICP source unit, described ICP source unit comprises:

Chamber, described chamber comprise open-topped chamber body and the dielectric window that covers the open top of described chamber body;

Antenna unit places the described dielectric window outside; With

The source current unit is used to provide source current to described antenna unit; And

Skew RF power subsystem is used to provide the bias RF power of having mixed high-frequency RF power and low frequency RF power to negative electrode, and described negative electrode is installed in the described chamber, and on the top of described negative electrode the installation targets wafer, described skew RF power subsystem comprises:

The high-frequency RF power subsystem is used to provide high-frequency RF power to described negative electrode; With

The low frequency RF power subsystem is parallel to described high-frequency RF power subsystem and is connected to described negative electrode,

And provide low frequency RF power to described negative electrode;

Wherein when the source current greater than setting power is provided for described antenna unit the plasma ion density in the described chamber greater than the plasma ion density in the described chamber when the source current less than described setting power is provided for described antenna unit

Wherein when the source current less than described setting power is provided for described antenna unit the plasma ion energy in the described chamber greater than the plasma ion energy in the described chamber when the source current greater than described setting power is provided for described antenna unit, and

Wherein said skew RF power subsystem provides the bias RF power of having mixed high-frequency RF power and low frequency RF power to negative electrode, thereby the plasma ion energy in the described chamber that takes place when being increased to greater than described setting power when the source current that offers described antenna unit reduces suddenly and compensates, thereby perhaps plasma ion density in the described chamber and energy is remained in the setting range.

2. reactor according to claim 1 wherein depends on the degree of ionization that injects the reacting gas in the described chamber and etch process is provided and etch process is provided in the high ionization zone at low ionized space,

Wherein when the source current less than described setting power is provided for described antenna unit, described plasma reactor is carried out etch process in described low ionized space, and when the source current greater than described setting power is provided for described antenna unit, described plasma reactor is carried out etch process in described high ionization zone, and

When described skew RF power subsystem provides the bias RF power of having mixed high-frequency RF power and low frequency RF power during to negative electrode, described setting power improves and described low ionized space expansion.

3. reactor according to claim 1, wherein when described plasma reactor was carried out etch process to the wafer with 200mm diameter, described setting power was in the scope of 500W to 700W.

4. reactor according to claim 1, wherein when described plasma reactor is carried out the real time chamber clean operation, described source current unit provides source current to described antenna unit, and described skew RF power subsystem stops to provide bias RF power to described negative electrode, and described plasma reactor is carried out the high density plasma chamber cleaning course under the situation that wafer is not installed on the described negative electrode.

5. reactor according to claim 1, wherein said skew RF power subsystem also comprises:

The source current switch unit is parallel to described high-frequency RF power subsystem and is connected to described negative electrode,

Wherein said source current switch unit switches to be opened so that described negative electrode is connected to ground connection by described source current switch unit, thereby is provided for described negative electrode by the source current that described source current unit produces when described source current switch unit is opened, and

Wherein form the closed-loop path when described negative electrode is connected to ground connection by described source current switch unit, this closed-loop path comprises described source current unit, described antenna unit, described negative electrode, described source current switch unit and described ground connection.

6. reactor according to claim 5, wherein said source current unit produce have the frequency that is lower than described low frequency RF power-frequency additional RF power as source current,

Wherein said skew RF power subsystem produces by described high-frequency RF power is mixed the bias RF power that obtains with described low frequency RF power, and

Wherein when described negative electrode is connected to ground connection and described high-frequency RF power subsystem and the work of low frequency RF power subsystem by described source current switch unit, described additional RF power and be provided for described negative electrode by described high-frequency RF power is mixed the bias RF power that obtains with described low frequency RF power.

7. reactor according to claim 5, wherein said source current unit produce have the frequency that is higher than described low frequency RF power-frequency and is lower than described high-frequency RF power-frequency additional RF power as source current,

Wherein said skew RF power subsystem produces by described high-frequency RF power is mixed the bias RF power that obtains with described low frequency RF power, and

Wherein when described negative electrode is connected to ground connection and described high-frequency RF power subsystem and the work of low frequency RF power subsystem by described source current switch unit, described additional RF power and be provided for described negative electrode by described high-frequency RF power is mixed the bias RF power that obtains with described low frequency RF power.

8. reactor according to claim 5, wherein said source current unit produce have the frequency that is higher than described high-frequency RF power-frequency additional RF power as source current,

Wherein said skew RF power subsystem produces by described high-frequency RF power is mixed the bias RF power that obtains with described low frequency RF power, and

Wherein when described negative electrode is connected to ground connection and described high-frequency RF power subsystem and the work of low frequency RF power subsystem by described source current switch unit, described additional RF power and be provided for described negative electrode by described high-frequency RF power is mixed the bias RF power that obtains with described low frequency RF power.

9. reactor according to claim 5, wherein said source current switch unit comprises:

The source current filter is used for getting rid of other frequency signals except the source current frequency to carrying out filtering by described negative electrode from the source current that described aerial coil receives; And

Switch is used for described source current filter being electrically connected to ground connection or being connected with ground connection disconnection.

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