WO2004021427A1

WO2004021427A1 - Plasma processing method and plasma processing device

Info

Publication number: WO2004021427A1
Application number: PCT/JP2003/010937
Authority: WO
Inventors: Toshihiko Shindo; Shin Okamoto; Kimihiro Higuchi
Original assignee: Tokyo Electron Limited
Priority date: 2002-08-30
Filing date: 2003-08-28
Publication date: 2004-03-11
Also published as: KR20050058464A; KR100782621B1; JP2004095909A; JP4322484B2; TWI324361B; TW200410332A; CN1679148A; AU2003261790A1; CN100414672C

Abstract

Argon gas is supplied into a vacuum chamber (1). Keeping this condition, relatively small high-frequency power such as 300W is supplied to a platform (2) (lower electrode) from a high-frequency power supply (11) in order to produce a weak plasma which acts on a semiconductor wafer (W) so as to adjust the condition of charge built up within it (W). During this adjustment, no DC voltage (HV) is applied to an electrostatic chuck (4) for ease of charge movement. Thereafter a direct current voltage is started to be applied to the electrostatic chuck (4), and then strong high-frequency power such as 2000W for a normal processing is supplied to produce a strong plasma, performing a normal processing. Thus, surface arching that possibly occurs in the processed substrate is avoided, improving the productivity compared to the conventional ones.

Description

Description Plasma processing method and plasma processing apparatus

The present invention relates to a plasma processing method and a plasma processing apparatus, and more particularly to a plasma processing method and a plasma processing apparatus for performing a plasma etching process or the like on a substrate to be processed such as a semiconductor wafer or an LCD substrate. Background art

BACKGROUND ART Conventionally, a plasma processing method for processing a substrate to be processed such as a semiconductor wafer or an LCD substrate by using plasma has been frequently used. For example, in a semiconductor device manufacturing process, as a technique for forming minute electric circuits on a substrate to be processed, for example, a semiconductor wafer, a thin film or the like formed on a semiconductor wafer is etched using plasma. Plasma etching is often used to remove.

In an etching apparatus for performing such a plasma etching process, for example, plasma is generated in a processing chamber (etching chamber) configured so that the inside can be hermetically closed. Then, a semiconductor wafer is placed on a susceptor provided in the etching chamber, and etching is performed.

Also, various types of means for generating the plasma are known. Among them, a device of the type that supplies high-frequency power to a pair of parallel plate electrodes provided so as to face each other up and down to generate plasma. One of the parallel plate electrodes, for example, the lower electrode also serves as a susceptor And a semiconductor wafer is placed on this lower electrode, A plasma is generated by applying a frequency voltage to perform etching.

However, in such an etching apparatus, during etching, so-called surface arcing in which a lightning-like abnormal discharge occurs on the surface of the semiconductor wafer may occur.

The surface arcing often occurs, for example, when an insulator layer is formed on a conductor layer and the insulator layer is etched. For example, when the insulator layer made of a silicon oxide film is etched to form a contact hole that leads to a conductor layer made of a lower metal layer, the silicon oxide film whose thickness has been reduced by etching is destroyed. In many cases, it occurs.

When such abnormal discharge occurs, many parts of the silicon oxide film in the semiconductor wafer are destroyed, and most of the elements on the semiconductor wafer become defective. At the same time, metal contamination occurs in the etching chamber, so that the etching process cannot be performed as it is, and the cleaning chamber in the etching chamber is required. For this reason, there was a problem that productivity was significantly reduced. Disclosure of the invention

Therefore, an object of the present invention is to provide a plasma processing method and a plasma processing apparatus which can prevent the occurrence of surface arcing on a substrate to be processed and can improve the productivity as compared with the related art. Things.

In the plasma processing method of the present invention, when performing plasma processing by applying plasma to a substrate to be processed, a plasma weaker than plasma used for the plasma processing is applied to the substrate before performing the plasma processing. And the state of electric charge of the substrate to be processed is kept constant, and thereafter, the plasma processing is performed. Further, in the plasma processing method of the present invention, in the plasma processing method, the weak plasma is applied to the substrate to be processed for a predetermined time, and thereafter, a DC voltage is applied to an electrostatic chuck for sucking and holding the substrate to be processed. It is characterized by applying.

Further, the plasma processing method of the present invention is characterized in that in the above-described plasma processing method, before applying the weak plasma, application of a DC voltage to the electrostatic chuck is started.

Further, in the plasma processing method of the present invention, in the above-described plasma processing method, the weak plasma is a plasma formed by an Ar gas, or a 〇2 gas, or a CF ₄ gas, or an N ₂ gas. I do.

Further, the plasma processing method of the present invention is characterized in that, in the above-mentioned plasma processing method, the weak plasma is formed by a high frequency power of 0.15 to 1.0 WZ cm 2.

The plasma processing method according to the present invention is the plasma processing method described above, wherein the weak plasma is applied to the substrate to be processed for 5 to 20 seconds.

Further, in the plasma processing method of the present invention, in the above-described plasma processing method, at the start of the plasma processing, after the application of high-frequency power for generating plasma is started, the application of a DC voltage to the electrostatic chuck is started. The application of the high-frequency power is stopped after the application of the DC voltage to the electrostatic chuck is stopped at the end of the plasma processing.

Further, in the plasma processing method of the present invention, in the above-mentioned plasma processing method, in a state where the substrate to be processed is supported by a support bar grounded by a conductor above the electrostatic chuck, a DC voltage of the electrostatic chuck is The application is started, and then the substrate is lowered and placed on the electrostatic chuck. It is characterized by doing.

Further, the plasma processing method of the present invention is characterized in that in the above-mentioned plasma processing method, the plasma processing is an etching processing, and the weak plasma is applied to the substrate to be processed in a processing chamber for performing the etching processing. And

Further, the plasma processing apparatus of the present invention is a plasma processing apparatus including a plasma processing mechanism for performing a plasma processing on a substrate to be processed, wherein the control unit controls the plasma processing mechanism and performs the plasma processing method. It is characterized by having. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram schematically showing a schematic configuration of an apparatus used in an embodiment of the present invention.

FIG. 2 is a view for explaining a plasma processing method according to one embodiment of the present invention.

FIG. 3 is a diagram schematically showing a schematic configuration of an apparatus used in another embodiment of the present invention.

FIG. 4 is a view for explaining a plasma processing method according to another embodiment of the present invention.

FIG. 5 is a view for explaining a plasma processing method according to a modification of the embodiment shown in FIG.

FIG. 6 is a diagram for explaining a chucking method using an electrostatic chuck.

FIG. 7 is a diagram for explaining a change in potential of each part in the checking method of FIG.

FIG. 8 is a diagram for explaining a change in potential of each part in another chucking method. FIG. 9 is a diagram for explaining a comparative example of a chucking method using an electrostatic chuck.

FIG. 10 is a diagram for explaining a change in potential of each part in the chucking method of FIG.

FIG. 11 is a diagram showing the relationship between the voltage applied to the electrostatic chuck and the number of particles.

1 2, the best mode for carrying out the Figure _c invention showing the difference in the number of particles due to the difference of the sequence

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows the overall configuration of a plasma processing apparatus (etching apparatus) used in an embodiment of the present invention. In the figure, reference numeral 1 denotes a cylindrical vacuum chamber which is made of, for example, aluminum and the like and is configured so as to be able to hermetically close the inside thereof, and which constitutes a processing chamber.

The vacuum chamber 11 is connected to a ground potential. Inside the vacuum chamber 1, there is provided a mounting table 2 made of a conductive material, for example, aluminum or the like in a block shape and also serving as a lower electrode.

The mounting table 2 is supported in a vacuum chamber 11 via an insulating plate 3 made of ceramic or the like. An electrostatic chuck 4 is provided on the mounting surface of the mounting table 2 on which the semiconductor wafer W is mounted. The electrostatic chuck 4 has a configuration in which an electrode 4 a for an electrostatic chuck is interposed in an insulating film 4 b made of an insulating material, and a DC power supply 5 is connected to the electrode 4 a for the electrostatic chuck. Have been. The electrostatic chuck electrode 4a is made of, for example, copper or the like, and the insulating film 4b is made of polyimide or the like.

In addition, the inside of the mounting table 2 has insulating properties as a heat medium for temperature control. A heat medium flow path 6 for circulating a fluid and a gas flow path 7 for supplying a temperature control gas such as a helium gas to the back surface of the semiconductor wafer W are provided.

Then, the mounting table 2 is controlled to a predetermined temperature by circulating an insulating fluid controlled at a predetermined temperature in the heat medium flow path 6, and the space between the mounting table 2 and the back surface of the semiconductor wafer W is controlled. A gas for temperature control is supplied through the gas flow path 7 to promote heat exchange between them, so that the semiconductor wafer W can be accurately and efficiently controlled to a predetermined temperature. I have.

Further, a focus ring 8 made of a conductive material or an insulating material is provided on the outer periphery above the mounting table 2, and a power supply for supplying high-frequency power is provided substantially at the center of the mounting table 2. Wire 9 is connected. A high-frequency power supply (RF power supply) 11 is connected to the power supply line 9 via a matching unit 10 so that a high-frequency power of a predetermined frequency is supplied from the high-frequency power supply 11. .

Outside the focus ring 8, there is provided an exhaust ring 12, which is formed in a ring shape and has a large number of exhaust holes, and through this exhaust ring 12, an exhaust port 13 is provided. The processing space in the vacuum chamber 11 is evacuated by a vacuum pump or the like of an exhaust system 14 connected to the vacuum chamber.

On the other hand, a shower head 15 is provided on the top wall portion of the vacuum chamber 11 above the mounting table 2 so as to face the mounting table 2 in parallel, and this shower head 15 is grounded. I have. Therefore, the shower head 15 and the mounting table 2 function as a pair of electrodes (an upper electrode and a lower electrode).

The shower head 15 is provided with a number of gas discharge holes 16 on the lower surface, and has a gas inlet 17 on the upper part. And A gas diffusion space 18 is formed inside the shower head 15. A gas supply pipe 19 is connected to the gas introduction section 17, and a gas supply system 20 is connected to the other end of the gas supply pipe 19. The gas supply system 20 includes a mass flow controller (MFC) 21 for controlling a gas flow rate, a processing gas supply source 22 for supplying, for example, a processing gas for etching, and an Ar gas. It consists of an Ar gas supply source 23 for supplying water.

On the other hand, an annular magnetic field forming mechanism (ring magnet) 24 is arranged around the outside of the vacuum chamber 11 concentrically with the vacuum chamber 11, and is located between the mounting table 2 and the shower head 15. A magnetic field is formed in the processing space. The whole of the magnetic field forming mechanism 24 is rotatable around the vacuum chamber 11 at a predetermined rotation speed by a rotating mechanism 25.

The plasma processing mechanism such as the DC power supply 5, the high-frequency power supply 11, and the gas supply system 20 for performing the plasma processing on the semiconductor wafer W is configured to be controlled by the control unit 40.

Next, the procedure of the etching process by the etching apparatus configured as described above will be described.

(First embodiment)

First, a gut valve (not shown) provided in the vacuum chamber 11 is opened, and a semiconductor wafer W is transferred by a transfer mechanism (not shown) through a load lock chamber (not shown) arranged adjacent to the gate valve. Is loaded into the vacuum chamber 1 and is mounted on the mounting table 2. Then, after the transfer mechanism is retracted out of the vacuum chamber 11, the gate valve is closed. At this time, the application of the DC voltage (HV) from the DC power supply 5 to the electrostatic chuck electrode 4a of the electrostatic chuck 4 was not performed.

Thereafter, vacuum is exhausted through the exhaust port 13 by the vacuum pump of the exhaust system 14. First, Ar gas is supplied from the Ar gas supply source 23 into the vacuum chamber 11 while evacuating the chamber 11 to a predetermined degree of vacuum. Then, in this state, as shown in FIG. 2, first, a high-frequency power having a relatively low power such as 30 OW (frequency of 13.5 6 MHz) to generate a weak plasma, which acts on the semiconductor wafer W.

The reason why the weak plasma is applied to the semiconductor wafer W is as follows.

That is, the state of the semiconductor wafer W to be processed is not uniform due to the processing state in a previous step (for example, a film forming step such as CVD). For example, electric charges are accumulated inside the semiconductor wafer w. May be. If strong plasma is applied in the state where the electric charge is accumulated inside the semiconductor wafer W, surface arcing or the like is likely to occur, so that the weak plasma is applied before the strong plasma is applied. The purpose of this is to uniformly adjust (initialize) the state and the like of the electric charge accumulated inside the semiconductor wafer W.

In adjusting the state of the electric charge accumulated inside the semiconductor wafer W, the electrode 4 a for the electrostatic chuck of the electrostatic chuck 4 is used to facilitate the movement of the electric charge from the inside of the semiconductor wafer W. The semiconductor wafer is adjusted (initialized) by such weak plasma without applying a DC voltage (HV) to the semiconductor wafer.

The high-frequency applied power for generating such a weak plasma is about 0.15 W / cm ² to about 1.0 WZ cm ² , for example, about 100 to 500 W. Is applied to the semiconductor wafer W, for example, about 5 to 20 seconds.

In the above description, Ar gas is used and plasma of Ar gas is applied. Case is described, but not gas species limited to this, For example, 0 ₂ gas, CF ₄ gas, a gas such as N ₂ gas may be used, however, when the selection of the gas species It is necessary to select a plasma gas to be generated to such an extent that an undesired action such as etching is caused on the semiconductor wafer W and on the inner wall of the vacuum chamber 11 and on the semiconductor wafer W, and It is necessary to select one that easily ignites the plasma. Furthermore, the optimum gas type may change depending on the type of processing performed on the semiconductor wafer W to be processed in the previous process. Is preferred.

Then, after the weak plasma is applied to the semiconductor wafer W as described above, as shown in FIG. 2, a DC voltage (HV) from the DC power supply 5 is applied to the electrostatic chuck electrode 4a. Thereafter, a predetermined processing gas (etching gas) is supplied from the processing gas supply source 22 into the vacuum chamber 11, and the high frequency power supply 11 supplies the gas to the mounting table 2 as a lower electrode. By supplying high-frequency power (frequency: 13.56 MHz) with high power for normal processing such as 0 W, strong plasma is generated and normal plasma processing (etching processing) is performed. In FIG. 2, the horizontal axis represents time, and the vertical axis represents the voltage value in the case of the electrostatic chuck HV, and the power value in the case of the RF output. _C At this time, the high frequency is applied to the mounting table 2 as the lower electrode. By the application of power, a high-frequency electric field is formed in the processing space between the upper head 15 as the upper electrode and the mounting table 2 as the lower electrode, and a magnetic field forming mechanism 24 is formed. Thus, a magnetic field is formed, and etching by plasma is performed in this state.

Then, when the predetermined etching process is performed, the etching process is stopped by stopping the supply of the high-frequency power from the high-frequency power supply 11. The semiconductor wafer W is placed in a vacuum chamber in a procedure reverse to the procedure described above. One outside Take it out.

As described above, first, a weak plasma is applied to the semiconductor wafer W.- After that, when the semiconductor wafer w is subjected to an etching process, the rate at which surface arcing occurs on the semiconductor wafer W is independent of the lot. , Almost zero (less than 1%). On the other hand, when the process is started without applying the weak plasma as described above, the rate at which surface arcing occurs on the semiconductor wafer W may be about 80% depending on the lot. The reason is that the semiconductor wafer W was charged in a process before etching, and such surface arcing is performed when the so-called Low-K film is formed by CVD in the previous process. a, _c thus the probability was high particularly generated, before starting the normal process, by the action of weak plasma to the semiconductor wafer W as described above, greatly reduced the rate at which the surface arcing occurs in the semiconductor wafer W I was able to confirm that I could.

By the way, in the above embodiment, as shown in FIG. 1, a case where a device having a configuration in which high-frequency power is applied only to the mounting table 2 as the lower electrode is described, for example, as shown in FIG. Thus, a so-called upper and lower application type plasma processing apparatus configured to apply high-frequency power from the high-frequency power supply 31 via the matching unit 30 to the first head 15 as the upper electrode as well. Can also be applied.

In this case, for example, as shown in FIG. 4, first, the application of low-frequency high-frequency power to the mounting table 2 as the lower electrode is started, and then the low-frequency power is applied to the upper electrode 15 as the upper electrode. The application of the high-frequency power is started, and the application of the high-frequency power to the mounting table 2 as the lower electrode is temporarily stopped here. Then, in this state, after the weak plasma is applied to the semiconductor wafer W for a predetermined period, the application of the high-frequency power to the shower head 15 as the upper electrode is also stopped, and the plasma is once extinguished. Thereafter, a DC voltage (HV) is applied to the electrostatic chuck electrode 4 a of the electrostatic chuck 4, and a normal high-frequency power (high-power high-frequency power) for processing on the mounting table 2 as the lower electrode is applied. The application of normal high-frequency power for processing (high-frequency high-frequency power) to the shower head 15 as the upper electrode is started in this order, and normal processing of the semiconductor wafer W is started.

In this way, the present invention can be applied to the upper and lower applied plasma processing apparatus.

In addition, in addition to applying weak plasma as described above, or by itself, it is also possible to reduce the charge inside the semiconductor wafer W by, for example, applying an ionizer to the semiconductor wafer W before starting the processing. preferable. By such an operation of the ionizer, the occurrence of surface arcing can be suppressed. The ionizer may be installed in the chamber or may be installed in another location outside the chamber.

By the way, in the plasma processing method shown in FIG. 2, an electrostatic chuck is applied in a state in which a weak high-frequency power is applied to the mounting table 2 serving as the lower electrode and a weak plasma is not applied. The application of DC voltage (HV) to the electrostatic chuck electrode 4a has started. As described above, when the application of the DC voltage (HV) to the chuck electrode 4a is started in a state where the high-frequency power is not applied after the weak high-frequency power is applied and the weak plasma is formed, When the application of DC voltage (HV) is started, a lightning-like discharge may occur, damaging the substrate. In such a case, as shown in FIG. 5, in a state where high-frequency power is applied to the mounting table 2 (a state in which weak plasma is generated), a DC voltage to the electrostatic chuck electrode 4 a ( By starting application of HV), the occurrence of discharge can be suppressed.

As described above, in the first embodiment, the method of forming a weak plasma using Ar gas before the plasma processing such as etching, and the electric charge for the electrostatic chuck at that time. The timing of applying the DC voltage to the pole 4a has been described.

(Second embodiment)

Next, a preferred example of the relationship between the timing of the application of high-frequency power and the timing of the application of a DC voltage to the electrostatic chuck electrode 4a when performing a plasma process such as an etching process will be described.

The electrostatic chuck 4 includes a bipolar type and a monopolar type, and these types include a Coulomb type and a Johnson-Rahbek type, respectively. Among them, when a monopolar electrostatic chuck 4 of Coulomb type is used, it is preferable that the semiconductor wafer W is suctioned in the following sequence. Figure 6 shows the sequence. The horizontal axis represents time, the vertical axis represents the applied high-frequency power value (W) for the dotted line, and the applied DC voltage value (V) for the solid line. That is, after the semiconductor wafer W is mounted on the mounting table 2 (electrostatic chuck 4), introduction of gas into the vacuum chamber 11 is started. Then, as shown by a dotted line in FIG. 6, first, application of high-frequency power is started to the mounting table 2 to generate plasma, and thereafter, as shown by a solid line in FIG. Apply DC voltage (HV) to electrode 4a.

Before the start of the application of the DC voltage (HV) to the electrostatic chuck electrode 4a. Since the semiconductor wafer W is not attracted to the electrostatic chuck 4, its temperature control is not sufficiently performed. For this reason, the high-frequency power applied to the mounting table 2 when generating plasma for the first time is set to a lower high-frequency power (for example, about 500 W) than when processing is performed. Therefore, it is preferable that the temperature of the semiconductor wafer W does not rise. Also, when the semiconductor wafer W is removed from the electrostatic chuck 4, as shown in the figure, after the plasma processing is completed, first, the applied high-frequency power value is reduced to a power value (0 (Not W). After this, the application of DC voltage (HV) to the electrostatic chuck electrode 4a was stopped. Thereafter, the application of high frequency power is stopped to extinguish the plasma. When the application of the DC voltage (HV) to the electrostatic chuck electrode 4a is stopped, a voltage (for example, about 200 V) having a polarity opposite to that of the suction is temporarily applied to the electrostatic chuck electrode 4a. A voltage is applied to a to remove the charge and facilitate removal of the semiconductor wafer W. The application of such a voltage of the opposite polarity is performed as needed. If the semiconductor wafer W can be easily removed from the controversial check 4 without applying the voltage of the opposite polarity, the application of the opposite polarity is performed. No voltage is applied.

Figure 4 shows the sequence of the chucking of the semiconductor wafer W by the electrostatic chuck 4 as described above. The copper electrode part (Cu) of the electrostatic chuck (ESC) and the polyimide insulating film part (PI ), The backside oxide layer (B.S.Ox) of the multi-layer semiconductor wafer (Multi Layer Wafer), the silicon substrate (Sisub) and the oxide layer (Ox), and the inside of the vacuum chamber. It shows changes in the potential of each part of the processing space (Space) and upper electrode part (Wall).

As shown in the figure, first, when the semiconductor wafer W is mounted on the mounting table 2 by lowering the wafer supporting pins provided on the mounting table 2, as shown by 部 in the figure, the potential of each part becomes In this state, when the introduction of gas into the vacuum chamber 11 is started thereafter, the potential of each part is in the state of zero as shown by ② in the figure.

Thereafter, when the application of high-frequency power is started to generate plasma, the potential of the semiconductor wafer W becomes a potential of about 100 V minus the number of negative electrodes determined by the state of the plasma, as shown by ③ in the figure.

Then, in this state, when the application of the DC voltage (HV) to the electrostatic chuck electrode 4a is started, the potential of the electrostatic chuck electrode 4a is changed to the applied DC voltage ( HV) (for example, about 1.5 KV), causing a potential difference in the insulating film portion (PI) and causing the semiconductor wafer W to be attracted. Is

As described above, according to the sequence of adsorption of the semiconductor wafer W by the electrostatic chuck 4 as described above, the DC voltage (HV) is applied to the surface of the semiconductor wafer W to the electrode 4 a for the electrostatic chuck. Since the accompanying high voltage is not applied, it is possible to prevent undesirable abnormal discharge from occurring on the surface of the semiconductor wafer W.

Note that the sequence described in the second embodiment for applying a DC voltage after applying high-frequency power has the following effects.

A sequence as shown in FIG. 9, that is, high-frequency power is applied to the lower electrode (or upper electrode) after applying a DC voltage to the electrostatic chuck electrode 4a at the start of the plasma processing, and high-frequency power is applied after the plasma processing is completed When the DC voltage is turned OFF after the OFF, a large voltage is applied to the semiconductor wafer W as shown in FIG. 10 when the semiconductor wafer W is attracted or desorbed. As a result, the surface of the semiconductor wafer W may be damaged, specifically, a chip having a diameter of about several m may be generated. Depending on a place where the chip is generated, arcing may occur during etching and a product defect may occur. . In addition, the chipped particles become particles and may adhere to the surface of the semiconductor wafer W.

However, in the case of the sequence described in this embodiment, in which RFON → HVON at the start of the process and HVOFF → RFOFF at the end of the process, the semiconductor wafer W is not damaged because a high voltage is not applied to the semiconductor wafer W. As a result, particles on the surface of the semiconductor wafer W can be prevented.

In addition, in the sequence shown in FIG. 9, even if the surface of the semiconductor wafer W is not damaged, the DC voltage is not applied to the electrostatic chuck electrode 4a. Since the semiconductor wafer W is more charged, the charged particles normally floating in the processing chamber may adhere to the semiconductor wafer w due to the electrostatic force.

However, in the case of the sequence of RFON → HVON at the start of the process and HVOFF → RFOFF at the end of the process, the high-frequency discharge is maintained before the DC voltage is applied to the electrostatic chuck. The particles are trapped in the ion sheath, and as a result, the adhesion of particles to the surface of the semiconductor wafer W can be reduced. There is also such an effect.

The results of verifying the effect of the trap in the ion sheath are shown below.

FIG. 11 shows the result of examining the difference in the number of adhered particles due to the difference in the magnitude of the DC applied voltage of the electrostatic chuck for adsorbing the semiconductor wafer W.

That is, first, a CF-based reactant serving as a source of particles is attached to the processing chamber 1 of the plasma processing apparatus (seasoning), and then the semiconductor wafer W is loaded into the processing chamber and placed on the electrostatic chuck. The semiconductor wafer W is placed on the semiconductor wafer W, and the processing gas is circulated for a certain period of time.After that, the semiconductor wafer W is neutralized and unloaded from the processing chamber. The DC voltage of the electrostatic chuck is 0 V, 1.5 kV, 2.0 kV, and 2.5 kV. In each case, This shows the results of an investigation.

As shown in the figure, it can be seen that increasing the DC applied voltage of the electrostatic chuck increases the number of particles adhering to the semiconductor wafer W. That is, it can be seen that the application of a DC voltage to the electrostatic chuck affects the adhesion of particles to the semiconductor wafer W. The processing conditions of the seasoning process were as follows: pressure: 6.65 Pa, high-frequency power: 350 W, gas used: C ₄ F ₈ / Ar / CH ₂ F ₂ = 1 3/60 0/5 sccm _s Wafer back pressure (center / peripheral): 1330Z3990Pa, temperature (ceiling / sidewall / bottom): 60/60/60 ° C, high frequency application time : 3 minutes.

The pressure, gas used, wafer backside pressure, and temperature conditions when the semiconductor wafer W is placed on the electrostatic chuck and gas is passed are the same as described above. 60 seconds.

Further, in the above static elimination step, the static elimination of the semiconductor wafer W is performed by applying a pressure of 26.6 Pa, an applied voltage of 1.5 kV, a voltage application time of 1 second, and a pressure of 53.2 Pa. , N: 100 sccm, time: 15 seconds, and static elimination of the electrostatic chuck was performed at an applied voltage of —2, OkV, and a voltage applied time of 1 second. It is to be noted that such static elimination is performed because the semiconductor wafer W after the process is conveyed may cause extra particles to adhere again if the semiconductor wafer W jumps when the semiconductor wafer W is transferred. Thereby, such a jump of the semiconductor wafer W does not occur.

Further, FIG. 1 2, after the seasoning process, placing the semiconductor wafer W to the processing chamber in one, generates a large number of particles from the reactant deposited in seasoning step performed 0 ₂ Doraiku cleaning in this state The number of particles adhering to the semiconductor wafer W is calculated in the order of RFON → HVON at the start of processing, HVOFF → RFOFF at the end of processing, and HVON → RFON at the start of processing and RFOFF → HVOFF at the end of processing. This shows the results of measurements for the case of the sequence described above. In this measurement, the seeds enging process and the static elimination process are the same as those described above, and the O ₂ dry cleaning process is performed under the following conditions: pressure: 13.3 Pa, high-frequency power: 1000 W, gas used: 0 ₂ = 1 0 0 0 sccm Wafer back pressure (central edge): 133 0

390 Pa, temperature (top and bottom): 60 / 60Z60 ° C, high-frequency application time: 30 seconds.

As shown in the figure, by adopting the sequence of RF ON → HV ON at the start of the process and HVOFF → RFOFF at the end of the process, the number of attached particles can be significantly reduced. As shown in the sequence of FIG. 8, the DC voltage applied to the electrostatic chuck electrode 4a while the semiconductor wafer W is supported by the wafer support pins (support rods) provided on the mounting table 2 (台). (HV) is applied (②), and thereafter, the semiconductor wafer W is placed on the mounting table 2 by lowering the wafer supporting pins (③, ④), and the semiconductor wafer w is also attracted. However, the surface of the semiconductor wafer w does not reach the potential of the applied DC voltage (HV). Therefore, even by such a suction sequence, it is possible to prevent occurrence of an undesirable abnormal discharge on the surface of the semiconductor wafer W. However, such a sequence cannot be performed unless the pins for supporting the wafer are conductive and electric charges are supplied to the semiconductor wafer W from the pins.

In addition, abnormal discharge that occurs when the electrostatic chuck is attracted by the above-described electrostatic chuck can be prevented by using a bipolar electrostatic chuck even with the same Coulomb-type electrostatic chuck.

In the above example, an embodiment of an etching process using a parallel plate type etching apparatus has been described. However, the present invention is not limited to such an embodiment, and it is needless to say that the present invention can be used for any plasma processing. It is. Further, in the above embodiment, the case where the weak plasma is applied in the vacuum chamber of the etching apparatus for performing the etching process has been described. The body wafer w can be initialized.

As described above in detail, according to the present invention, it is possible to prevent surface arcing occurring on a substrate to be processed and to improve productivity as compared with the related art. Industrial applicability

The plasma processing method and the plasma processing apparatus according to the present invention can be used in a semiconductor manufacturing industry or the like that manufactures semiconductor devices.

Therefore, it has industrial applicability.

Claims

The scope of the claims

1. In performing plasma processing by applying plasma to a substrate to be processed, before performing the plasma processing, a plasma weaker than the plasma used for the plasma processing is applied to the substrate to be processed, and the plasma processing is performed. A plasma processing method characterized in that the state of charge on a substrate is kept constant, and thereafter, the plasma processing is performed.

2. The plasma processing method according to claim 1,

A plasma processing method, comprising: applying the weak plasma to the substrate to be processed for a predetermined time; and thereafter, applying a DC voltage to an electrostatic chuck for suction-holding the substrate to be processed.

3. In the plasma processing method according to claim 2,

A plasma processing method characterized by starting applying a DC voltage to the electrostatic chuck before extinguishing the weak plasma.

4. In the claims 1-3 plasma processing method according to any one, said weak plasma, A r gas, or 0 ₂ gas, or CF ₄ gas, also a plasma formed by the N ₂ gas A plasma processing method characterized by the following.

5. The plasma processing method according to any one of claims 1 to 4, wherein the weak plasma is formed by a high-frequency power of 0.15 to 1.0 WZ cm2. .

6. The plasma processing method according to any one of claims 1 to 5, wherein the weak plasma is applied to the substrate to be processed for 5 to 20 seconds.

7. The plasma processing method according to any one of claims 1 to 6, wherein at the start of the plasma processing, a high-frequency power for generating plasma is provided. After the application of force is started, the application of a DC voltage to the electrostatic chuck is started.At the end of the plasma processing, the application of the DC voltage to the electrostatic chuck is stopped, and then the application of the high-frequency power is stopped. A plasma processing method.

8. The plasma processing method according to any one of claims 1 to 6, wherein the substrate to be processed is supported by a support bar grounded by a conductor above the electrostatic chuck, and a DC voltage is applied to the electrostatic chuck. A plasma processing method comprising: starting application of a substrate; thereafter, lowering the substrate to be processed and mounting the substrate on the electrostatic chuck.

9. The plasma processing method according to any one of claims 1 to 8, wherein the plasma processing is etching processing, and the weak plasma is caused to act on the substrate to be processed in a processing chamber that performs the etching processing. A plasma processing method comprising:

10. A plasma processing apparatus comprising a plasma processing mechanism for performing plasma processing on a substrate to be processed, wherein the plasma processing mechanism is controlled to perform the plasma processing method according to any one of claims 1 to 9. A plasma processing apparatus comprising: