TWI420588B - Plasma etching method - Google Patents

Description

Plasma etching method

The present invention relates to a plasma etching method, and in particular to a plasma etching method for etching a metal film of Ti or the like using a plasma of a reactive gas.

In the semiconductor device, a metal such as titanium (Ti) is used as a wiring material, for the purpose of reducing parasitic resistance of a MOS transistor or the like, and is used for alloying. For example, in the manufacturing process of the MOS transistor, a process of forming a Ti film on the surface of the gate electrode and the diffusion layer, heat-treating the alloy, and removing the unreacted Ti film is performed. In the technique of removing the Ti film formed on the substrate by etching, a method of dry etching by a plasma of a CF ₄ -based etching gas has been proposed (for example, Patent Document 1 and Patent Document 2).

[Patent Document 1] Japanese Laid-Open Patent Publication No. SHO-53-118372 (Patent Document No. 5)

Generally, from the viewpoint of output improvement, the etching rate is preferably higher, and in the case of etching the Ti film, high etching rate processing is also required. However, the above-described prior art method does not consider the fact that the etching rate is made faster. For example, in the method of Patent Document 2, in order to make the build speed faster, in the etching after performing the pre-etching, even an etching rate of about 30 to 40 nm/min can be obtained (refer to the document, Fig. 1), after all, Can not meet the requirements of the current high-speed etching.

On the other hand, when the Ti film is etched at a high speed by the plasma of the CF-based gas described in Patent Documents 1 and 2, a re-adhesion phenomenon called an etching residue of a fence occurs. This phenomenon is based on the strong sputtering effect at the time of high-speed etching, and the etching residue such as Ti scatters and adheres to the side of the photoresist and other metal materials. This fence is responsible for the pollution caused by Ti and is required to be avoided as much as possible.

In addition, when the plasma is etched into the Ti film, a large amount of intracavity deposits are formed. This deposit is a cause of particle contamination and hinders the manufacture of a highly reliable semiconductor device. Therefore, in the plasma etching of the Ti film, it is necessary to take countermeasures against the deposit in the cavity.

Accordingly, it is an object of the present invention to provide: first, to avoid the generation of a fence, and to etch a plasma etching method of Ti at a high etching rate, and further to provide for suppressing the generation of deposits in the cavity during the etching process. A plasma etching method that prevents particles from being contaminated.

In order to solve the above problems, according to a first aspect of the present invention, in order to provide a plasma etching method, in a processing container which can be kept in a vacuum, at least a plasma of an etching gas is applied to form a specific shape. The patterned mask layer and the object to be treated as the Ti layer of the layer to be etched under the mask layer are etched to form the Ti layer, which is characterized by using an etching gas containing a fluorine compound in the chamber pressure Etching is performed below 4Pa.

In the plasma etching method of the first aspect, the fluorine compound is contained, and CF _{4 is} preferred. In addition, the etching rate is preferably from 90 to 140 nm/min.

According to a second aspect of the present invention, there is provided a plasma etching method comprising: forming, in a processing container which can be kept in a vacuum, at least a mask layer on which a pattern having a specific shape is formed, and forming The object to be treated of the Ti layer under the mask layer is subjected to a plasma having a fluorine compound-containing etching gas at a pressure of 4 Pa or less in the chamber to etch the first plasma treatment of the Ti layer. After the completion of the first plasma treatment project, the second plasma treatment project for dry cleaning is introduced into the processing chamber by the plasma of the cleaning gas, and in the second plasma treatment project, The deposit of the Ti compound produced by the first plasma treatment project is removed.

In the plasma etching method of the second aspect, it is preferable to repeatedly perform the first plasma treatment process and the second plasma treatment process. Further, the cleaning gas used in the second plasma treatment project is preferably a gas containing a fluorine compound or oxygen. Here, the fluorine compound is preferably NF ₃ or CF ₄ .

Further, the pressure in the chamber in the second plasma treatment project is preferably 6.7 Pa or less.

According to a third aspect of the present invention, a control program is provided which is characterized in that it operates on a computer and, when executed, controls the plasma processing apparatus to perform the plasma etching method of the first aspect or the second aspect.

According to a fourth aspect of the present invention, in a computer memory medium, a control program for storing an operation on a computer is provided, wherein the control program controls the first viewpoint or the second viewpoint when the control program is executed. A plasma processing apparatus used in a plasma etching method.

According to a fifth aspect of the present invention, there is provided a plasma etching apparatus comprising: a plasma supply source for generating a plasma; and a processing chamber for separating an object to be processed by the plasma a processing container, a support body on which the object to be processed is placed, an exhaust means for decompressing the inside of the processing container, a gas supply means for supplying a gas into the processing container, and a control in the processing container The control unit of the plasma etching method of the first aspect or the second aspect is performed.

According to the plasma etching method of the present invention, the etching gas system uses a gas containing a fluorine compound, and plasma etching is performed under a specific low pressure condition, whereby the Ti film can be etched while maintaining a high etching rate. Moreover, it is possible to effectively prevent the occurrence of a fence.

Further, by combining the plasma etching treatment and the plasma cleaning treatment under specific conditions, accumulation of deposits in the cavity can be suppressed, and particle contamination can be prevented, so that the reliability of the semiconductor device can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a schematic cross-sectional view showing a plasma etching apparatus 100 of a magnetron RIE type which can be suitably used for the purpose of carrying out the method of the present invention. The etching apparatus 100 is configured to be airtight, and is formed in a cylindrical shape including a small diameter upper portion 1a and a large diameter lower portion 1b. The wall portion has, for example, a cavity (processing container) 1 made of aluminum.

In the cavity 1, a support stage 2 for supporting a semiconductor wafer (hereinafter, simply referred to as "wafer") W having a substrate of a Ti film as a target to be processed is provided. The support stage 2 is made of, for example, aluminum, and is supported by the support base 4 of the conductor via the insulating plate 3. Further, on the outer circumference above the support stage 2, for example, a focus ring 5 formed of Si or quartz or the like is provided. The support mounting table 2 and the support table 4 can be lifted and lowered by a ball screw mechanism including a ball screw 7, and the driving portion below the support table 4 is covered with a bellows 8 made of stainless steel (SUS). A bellows cover 9 is provided on the outer side of the 8. Further, a baffle 10 is provided on the outer side of the focus ring 5 described above. In addition, the cavity 1 is grounded.

An exhaust port 11 is formed in a side wall of the lower portion 1b of the chamber 1, and an exhaust system 12 is connected to the exhaust port 11. Further, by operating the vacuum pump of the exhaust system 12, the inside of the chamber 1 can be decompressed to a specific degree of vacuum. On the other hand, a gate valve 13 for loading and unloading the switch wafer W is provided on the upper side of the side wall of the lower portion 1b of the chamber 1.

The first high-frequency power source 15 for forming a plasma is connected to the support stage 2 via the matching unit 14, and high-frequency power of a specific frequency is supplied from the first high-frequency power source 15 to the support stage 2. On the other hand, facing the support stage 2, the shower head 20 which will be described later in detail is provided in parallel with each other, and the shower head 20 is grounded. Therefore, the support stage 2 and the shower head 20 function as a pair of electrodes.

An electrostatic chuck 6 for holding and holding the electrostatically adsorbed wafer W is provided on the surface of the support stage 2. The electrostatic chuck 6 is formed by the presence of an electrode 6a between the insulators 6b, and a DC power source 16 is connected to the electrode 6a. Further, by applying a voltage from the power source 16 to the electrode 6a, the wafer W is adsorbed by an electrostatic force such as a Coulomb force.

A temperature adjustment medium chamber 17 is provided inside the support stage 2, and in the temperature adjustment medium chamber 17, the temperature adjustment medium is introduced through the introduction tube 17a, and is discharged from the discharge tube 17b to circulate the heat. (warm, hot and cold) is transmitted to the wafer W via the support stage 2, whereby the processing surface of the wafer W is controlled to a desired temperature.

Further, even if the chamber 1 is exhausted by the exhaust system 12 and kept in a vacuum, the wafer W can be efficiently temperature-regulated by circulating the temperature regulating medium in the temperature adjusting medium chamber 17, as a heat transfer medium. The gas system is introduced into the surface of the electrostatic chuck 6 and the back surface of the wafer W at a specific pressure (back pressure) by the gas introduction mechanism 18 through the gas supply line 19. As described above, by introducing the gas as the heat transfer medium, the heat of the temperature adjustment medium is efficiently transmitted to the wafer W, and the temperature adjustment efficiency of the wafer W can be improved.

The aforementioned shower head 20 is disposed on the wall portion of the cavity 1 and faces the support stage 2. The shower head 20 is provided with a plurality of gas discharge holes 22 on the lower side thereof, and a gas introduction portion 20a at the upper portion thereof. Then, a space 21 is formed inside thereof. A gas supply pipe 23a is connected to the gas introduction portion 20a, and a processing gas supply system 23 that supplies a processing gas such as an etching gas and a cleaning gas is connected to the other end of the gas supply pipe 23a.

The processing gas is supplied from the processing gas supply system 23 to the space 21 of the shower head 20 through the gas supply pipe 23a and the gas introduction portion 20a, and is discharged from the gas discharge hole 22.

On the other hand, a pair of upper and lower bipolar annular magnets 24a and 24b are arranged concentrically around the upper portion 1a of the chamber 1. The two-pole annular magnets 24a and 24b are each formed by a plurality of anisotropic segment columnar magnets 31 attached to a ring-shaped magnetic body casing 32 as shown in the horizontal cross-sectional view of Fig. 2 . Among the particles, 16 anisotropic segment columnar magnets 31 having a circular shape are arranged in a ring shape. In Fig. 2, the arrow shown in the anisotropic segment columnar magnet 31 indicates the direction of magnetization, and as shown in the figure, the magnetization directions of the plurality of anisotropic segment columnar magnets 31 are slightly shifted. Forming a horizontal magnetic field B that is oriented in one direction as a whole.

Therefore, as shown in the model diagram of Fig. 3, in the space between the support stage 2 and the shower head 20, the electric field EL in the vertical direction is formed by the first high-frequency power source 15, and is ring-shaped by the dipole. The magnets 24a, 24b are formed with a horizontal magnetic field B, and the magnetron discharge is generated by the orthogonal electromagnetic field thus formed. Thereby, a plasma of an etching gas of a high energy state can be formed, and the wafer W can be etched.

Further, each component of the plasma etching apparatus 100 is configured to be connected to a process controller 50 including a CPU and controlled. The process controller 50 is connected to a display formed by a keyboard that the engineering administrator performs a command input operation for managing the plasma etching apparatus 100, and a display that visualizes the state of the plasma etching apparatus 100. Interface 51.

Further, the process controller 50 is connected to a memory unit 52 that stores a processing program for recording control programs and processing condition data and the like which are executed by the process controller 50 to realize various processes executed by the plasma etching apparatus 100.

Further, if necessary, the arbitrary processing program is called from the memory unit 52 by an instruction from the user interface 51 or the like, and the process controller 50 is executed to perform the power control under the control of the process controller 50. The desired processing of the slurry etching apparatus 100. Further, the processing program may be, for example, a state of a readable memory stored in a CD-ROM, a hard disk drive, a floppy disk drive, a non-volatile memory, or the like, or may be transmitted from another device, for example, through a dedicated line. And use.

Next, a plasma etching method according to the first embodiment of the method of the present invention using the plasma etching apparatus 100 thus constructed will be described with reference to Fig. 4 as appropriate.

First, the gate valve 13 of Fig. 1 is opened, the wafer W is carried into the chamber 1, and after being placed on the support stage 2, the support stage 2 is raised to the position shown in the figure, and the vacuum pump of the exhaust system 12 is used. The chamber 1 is evacuated through the exhaust port 11. As shown in FIG. 4(a), the wafer W in this state is formed by laminating an SiO ₂ layer 102 of an insulating oxide film, a Ti layer 103 as an etched layer, and a mask layer 104 on the Si substrate 101. . The mask layer 104 is not particularly limited as long as it has etching selectivity with the Ti layer 103. For example, a hard mask made of metal or the like, or an upper layer formed by other processes may be used. Further, a pattern of a specific shape is formed on the mask layer 104.

Then, the processing gas containing the etching gas and the diluent gas is introduced into the chamber 1 from the processing gas supply system 23 at a specific flow rate, and the pressure in the chamber 1 is set to 4 Pa (30 mTorr) or less, and the wafer W (supporting table 2) is placed. The temperature is set to 50 to 80 ° C. In this state, the specific high-frequency power is supplied from the first high-frequency power source 15 to the support stage 2 . The high-frequency power to generate the plasma is preferably 2,000 W or more, and more preferably 3,000 to 5,000 W, from the viewpoint of increasing the etching rate. At this time, the wafer W is applied to the electrode 6a of the electrostatic chuck 6 from the DC power source 16 by a specific voltage, for example, by the Coulomb force, and is held by the electrostatic chuck 6, and the shower head 20 of the upper electrode and A high-frequency electric field is formed between the support stages 2 of the lower electrodes. Between the shower head 20 and the support stage 2, the horizontal magnetic field B is formed by the bipolar annular magnets 24a and 24b. Therefore, an orthogonal electromagnetic field is formed in the processing space between the electrodes in which the wafer W exists. The resulting electron drift causes a magnetron discharge. Then, the wafer W is etched by the plasma of the etching gas formed by the discharge of the magnetron. In this case, in the usual etching, by setting the pressure in the chamber 1 to be higher, not only the charged particles of the single ions and the electrons, a sufficient amount of active groups can be generated, and the active group can effectively act. The etch rate is increased. Further, if the pressure is low, the sputtering effect is enhanced, and a fence is easily generated. From the viewpoint of the conventional etching, a relatively high pressure condition of 6.7 Pa (50 mTorr) or more is employed. However, in the present embodiment, in the plasma etching of the Ti layer 103, as will be described later, by using a low pressure condition of 4 Pa or less (that is, a range of 0 to 4 Pa), it is possible to prevent the occurrence of a fence, for example, one side. A high-speed etching of 90 to 140 nm/min is achieved.

In the present embodiment, the plasma generating mechanism of the REI type is used to apply high-frequency power to the support stage 2 on which the lower electrode of the wafer W is placed, and plasma can be formed directly above the object to be processed. Further, by forming a magnetic field orthogonal to the electric field between the electrodes, etching is performed to cause the electrons to trace the spiral orbit, and the chance of impact with the gas molecules can be increased. Therefore, high plasma can be realized directly above the object to be processed. density. With this, it can be etched at a higher speed.

As the processing gas used in the first etching process, it is preferable to use a fluorine-containing compound gas having high reactivity from the viewpoint of etching the wafer W at a high speed. Here, examples of the fluorine compound include CF ₄ , C ₃ F ₈ , SF ₆ , S ₂ F _{1 0} , CHF ₃ , CH ₂ F ₂ , C ₄ F ₈ and the like. Further, as the fluorine compound, for example, a rare gas such as Ar, Xe or Kr or an inert gas such as N _{2 may} be used.

Further, the gas introduction means 18 passes through the gas supply line 19, and the gas of the heat medium (warm or cold) which is efficiently supplied to the wafer W is introduced into the electrostatic chuck 6 at a specific pressure (back pressure). Between the surface and the back of the wafer W. For this gas, for example, He or the like can be used.

The first high-frequency power source 15 for plasma generation is appropriately set in order to form a desired plasma. From the viewpoint of increasing the density of the plasma directly above the wafer W, it is preferable that the frequency is 10 MHz or more.

In order to increase the density of the plasma directly above the wafer W, the bipolar annular magnets 24a and 24b apply a magnetic field to the processing space between the support stage 2 and the shower head 20 of the counter electrode, but in order to make the effect effective. It is preferable to use a strong magnet that can form a magnetic field of 10000 μT (100 G) or more in the processing space. The stronger the magnetic field, the more the effect of increasing the plasma density can be increased, but from the viewpoint of safety, it is preferably 100000 μT (1 kG) or less.

In the etching process, as shown in Fig. 4(a), the Ti layer 103 is etched, for example, by CF ₄ gas plasma. At this time, in the method of the present invention, for example, high-speed etching at a high etching rate of 90 to 140 nm/min can be performed. At a low-voltage plasma etching treatment of 4 Pa or more, Ti constituting the Ti layer 103 becomes TiF4, and is evaporated by the low vapor pressure. With this low-pressure etching mechanism, the occurrence of a fence can be prevented. Then, Ti which is formed into the Ti layer 103 by etching is removed from the SiO ₂ layer 102 except for the region which is covered by the mask layer 104. The remaining Ti layer 103 is patterned in the same pattern as the mask layer 104 as shown in Fig. 4(b).

Here, the test results confirming the effects of the present invention will be described.

The wafer W having the Ti layer 103 having the same configuration as that of Fig. ₄ is subjected to CF ₄ and Ar as an etching gas system under the following conditions, using the plasma etching apparatus 100 having the same structure as that of Fig. 1 . Plasma etching of the Ti layer 103.

<Condition 1> Magnetic field strength = 12000 μ T (120 G) slope magnet; magnetic field tilt = 8.53 deg; pressure in chamber 1 = 4 Pa (30 mTorr); high frequency power = 4000 W; CF ₄ / Ar flow = 300 / 600 ml / Min (sccm); distance between upper and lower electrodes (the distance between the lower surface of the shower head 20 and the upper surface of the support stage 2, the same below) = 40 mm; He back pressure (center/edge portion) = 1333/3332.5 Pa (10/25 Torr) ); the temperature of the shower head 20 = 60 ° C; the temperature of the side wall of the chamber 1 = 60 ° C; the temperature of the support table 2 = 50 ° C; processing time = 53.7 seconds

<Condition 2> Plasma etching was performed in the same manner as in Example 1 except that the pressure in the chamber was 6.7 Pa and the treatment time was 94.8 seconds.

After the plasma etching treatment, the individual wafers W of Condition 1 and Condition 2 were observed by a scanning electron microscope (SEM). In the case of Condition 2, the sputtering force was weaker than Condition 1, although it was a high voltage. In the treatment, a vertical stripe pattern of the fence is observed on the side wall of the mask layer 104. On the other hand, in the case of Condition 1, no occurrence of a fence was observed (both of which are omitted from the results).

Further, after the etching of Condition 1, the deposit in the chamber 1 was subjected to XPS analysis, and the peak of Ti was detected. Fig. 5 shows the result of waveform separation of this Ti peak. From Fig. 5, it is proved that Ti contained in the deposit is mostly present in the form of TiF ₄ .

In the condition 2 of the high pressure treatment of 6.7 Pa, the etching rate was as high as 140 nm/min. However, as described above, it was confirmed that a fence was formed by etching a Ti layer 103 containing a fluorine gas plasma. The etch rate increase and fence suppression have a compromise relationship. On the other hand, in the condition 1, the occurrence of the fence can be prevented, and the etching rate is 90 nm/min, and high-speed etching can be realized at a practically sufficient etching rate.

From the above, the plasma containing the fluorine gas is subjected to an etching treatment under a low pressure condition of 4 Pa or less, and Ti which constitutes the Ti layer 103 is changed to TiF4, and is evaporated and removed. In the etching by this method, it was confirmed that the occurrence of the barrier of Ti adhering to the photoresist and other metal films due to sputtering can be prevented.

Next, a plasma etching method according to a second embodiment of the present invention in which the plasma etching method is combined with the cleaning process of the plasma etching method according to the first embodiment will be described. When the plasma etching treatment of the first embodiment is carried out, a large amount of deposits are generated in the chamber 1. When this deposit was subjected to XPS analysis, it was known that TiF ₄ and CF compound were mixed. This deposit is in the form of a powder, and is a member attached to the periphery of the wafer W, particularly when the upper top plate (the member disposed at the lower portion of the shower head 20 in FIG. 1 is omitted) is deposited as a fine particle. Therefore, by performing a combination of the plasma etching treatment and the dry cleaning treatment, a stable plasma etching treatment can be performed.

Fig. 6 is a flow chart showing the processing procedure of the plasma etching method of the second embodiment. First, in step S101, the Ti general wafer on which the Ti layer 103 is formed is carried into the chamber 1, and in step S102, a plasma etching process is performed. The plasma etching treatment in the steps S101 and S102 is performed in the same manner as in the first embodiment.

After the plasma etching process is completed, in step S103, after the necessary processing such as pressure adjustment after etching, the gate valve 13 of Fig. 1 is opened, and the wafer W is carried out from the chamber 1. Next, in step S104, the bare Si wafer is carried into the chamber 1. A bare Si wafer does not have a clean wafer such as a thin film.

In step S105, a plasma cleaning process is performed on the bare Si wafer. For the processing gas in the plasma cleaning, for example, a fluorine compound containing NF ₃ , CF ₄ or the like and a gas such as O ₂ may be suitably used. Further, the processing gas may contain, for example, a rare gas such as Ar, Xe, Kr, or He or an inert gas such as N ₂ . The pressure of the cleaning treatment in the step S105 is preferably 6.7 Pa or less (that is, a range of 0 to 6.7 Pa) from the viewpoint of improving the cleaning efficiency, more preferably 4 Pa or less, and desirably 2 Pa or less. Further, the temperature of the cleaning treatment is preferably 50 ° C or more, more preferably 80 ° C or more.

Here, the results of reviewing the influence of the type of the treatment gas on the cleaning effect will be described. The treatment gas system was cleaned by three kinds of a mixed gas of CF ₄ /Ar, a mixed gas of NF ₃ /Ar, and O ₂ gas (separate) under the conditions shown below, and the thickness of the deposit in the upper top plate was measured.

CF ₄ /Ar gas: magnetic field strength = 12000 μ T (120G) slope magnet; magnetic field tilt = 8.53 deg; pressure in chamber 1 = 4 Pa (30 mTorr); high frequency power = 4000 W; CF ₄ / Ar flow = 300 / 600ml/min (sccm); distance between upper and lower electrodes = 40mm; He back pressure (center/edge) = 1333/3332.5Pa (10/25Torr); temperature of shower head 20 = 80 °C; temperature of side wall of cavity 1 = 60 ° C; temperature of support table 2 = 50 ° C; treatment time = 90 seconds NF ₃ /Ar gas: Except that NF ₃ /Ar gas was used, it was carried out under the same conditions as CF ₄ /Ar gas.

O ₂ gas: O ₂ flow rate = 900 ml/min (sccm), magnetic field tilt = 12.88 deg, and was carried out under the same conditions as CF ₄ /Ar gas.

The measurement point of the deposit is defined as the center portion (C) and the edge portion (E3) of the upper top plate, and between the middle portion (C) and the intermediate portion (M), at a slight interval from the center portion (C) side. 1 edge portion (E1) and second edge portion (E2) (the same applies hereinafter). Figure 7 shows the result.

From Fig. 7, the gas with the highest effect is NF ₃ /Ar, and O ₂ has the effect of almost completely cleaning the upper top plate. The CF ₄ /Ar system knows the first edge portion (E1) compared with the other two gas systems. The cleaning effect is weak. As a result, for example, in the NF ₃ /Ar gas, it is treated separately, and in the CF ₄ /Ar gas treatment, in combination with the O ₂ gas treatment, for example, after the CF ₄ /Ar gas treatment, O ₂ gas treatment can be expected to have sufficient cleaning effect.

Next, Fig. 8 shows the results of a review of the effect of the treatment pressure on the cleaning effect. The pressure (gas flow rate) was changed using O ₂ gas (separate) under the conditions shown below, and cleaning was performed to measure the thickness of the deposit in the upper top plate.

Cleaning conditions: magnetic field strength = 12000 μ T (120G) slope magnet; magnetic field tilt = 12.88 deg; pressure in chamber 1 = 4 Pa (30 mTorr) or 2 Pa (15 mTorr); high frequency power = 4000 W; O ₂ flow = 900 ml / Min (sccm) or 450ml/min (sccm); distance between upper and lower electrodes = 40mm; He back pressure (center/edge) = 1333/3332.5Pa (10/25Torr); temperature of shower head 20 = 80 °C; cavity 1 side wall temperature = 60 ° C; support table 2 temperature = 50 ° C; processing time = 90 seconds

From Fig. 8, by reducing the pressure in the chamber from 4 Pa (30 mTorr) to 2 Pa (15 mTorr), the film thickness of the deposit becomes thinner in almost the entire area of the upper top plate, and the cleaning effect is improved.

In the processing step of Fig. 6, after the cleaning is completed, the necessary processing such as pressure adjustment is performed, and in step S106, the gate valve 13 of Fig. 1 is opened to carry out the wafer W from the chamber 1. Next, the process returns to step S101 again to perform processing of a new Ti general wafer. Cleaning can also be performed after etching a certain number of wafers (for example, one batch) of wafer W. However, as shown in Fig. 6, each time the plasma is etched to treat one piece of Ti wafer, the cavity is implemented. 1 plasma cleaning is better. Thereby, the deposit in the chamber 1 can be removed, and a stable plasma etching treatment can be performed while preventing the contamination of the particles.

Fig. 9 is a view showing the result of measuring the number of fine particles of 0.5 μm or more in the case where the Ti general wafer is plasma-etched by the microparticle counter according to the flow chart of Fig. 6 under the following conditions. In addition, for comparison, the results when cleaning is not performed are also described together.

Etching conditions: magnetic field strength = 12000 μ T (120G) slope magnet; magnetic field tilt = 8.53 deg; pressure in chamber 1 = 4 Pa (30 mTorr); high frequency power = 4000 W; CF ₄ / Ar flow = 300 / 600 ml / min (sccm); distance between upper and lower electrodes = 40 mm; He back pressure (center/edge portion) = 1333/3332.5 Pa (10/25 Torr); temperature of shower head 20 = 60 ° C; temperature of side wall of chamber 1 = 60 ° C; Supporting the temperature of the mounting table 2 = 50 ° C; processing time = 90 seconds Cleaning conditions: magnetic field strength = 12000 μ T (120G) slope magnet; magnetic field tilt = 8.53 deg; pressure in chamber 1 = 4 Pa (30 mTorr); Power = 4000W; NF ₃ /Ar flow = 300/600ml/min (sccm); distance between upper and lower electrodes = 40mm; He back pressure (center/edge) = 1333/3332.5Pa (10/25Torr); shower head 20 Temperature = 80 ° C; temperature of the side wall of the chamber 1 = 60 ° C; temperature of the support table 2 = 50 ° C; processing time = 90 seconds

According to Fig. 9, when the plasma cleaning is not performed, the number of processed wafers increases with the number of wafers of Ti, and the number of fine particles increases. On the other hand, by the plasmon type plasma cleaning, the fine particles hardly occur, and it is revealed that a highly reliable semiconductor device can be manufactured.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible.

For example, in the above-described embodiment, the magnetic field forming means of the magnetron RIE plasma etching apparatus 100 uses a dipole magnet, but is not limited thereto, and may be formed under the pressure of the range of the present invention. As the slurry, various plasma etching apparatuses 100 such as a capacity coupling type and an inductive coupling type which do not use a magnetic field can be used.

Further, in the above embodiment, the Ti layer 103 is etched according to the pattern of the mask 104. However, the present invention is not limited thereto, and can be applied to the entire etching of the Ti layer.

1. . . Cavity (processing container)

2. . . Supporting table (electrode)

12. . . Exhaust system

15. . . First high frequency power supply

17. . . Temperature regulation media room

18. . . Gas introduction mechanism

20. . . Shower head (electrode)

twenty three. . . Process gas supply system

24a, 24b. . . Bipolar ring magnet

100. . . Plasma etching device

101. . . Si substrate

102. . . SiO ₂ layer

103. . . Ti layer

104. . . Mask layer

W. . . Wafer

Fig. 1 is a schematic cross-sectional view showing a magnetron RIE plasma etching apparatus for carrying out the method of the present invention.

Fig. 2 is a horizontal sectional view schematically showing a bipolar ring magnet arranged in a state around the cavity of the apparatus of Fig. 1.

Figure 3 is a model diagram showing the electric and magnetic fields formed in the cavity.

Fig. 4 is a view showing the steps of the electrode etching method according to the first embodiment of the present invention, wherein (a) is etching, and (b) is a state diagram after completion of etching.

Fig. 5 is a graph showing the results of waveform separation results by XPS analysis of the deposits in the cavity after the plasma etching treatment.

Fig. 6 is a flow chart showing the processing procedure of the plasma etching method according to the second embodiment of the present invention.

Fig. 7 is a graph showing the measurement results of the thickness of the deposit in the top plate after the cleaning treatment is performed by changing the processing gas.

Fig. 8 is a graph showing the measurement results of the thickness of the deposit in the top plate after the cleaning treatment is performed by changing the pressure.

Fig. 9 is a graph showing the relationship between the number of wafer processed sheets and the fine particles in plasma etching.

Claims (7)

A plasma etching method comprising: in a processing container that can be kept in a vacuum, at least a photomask layer formed with a pattern forming a specific shape, and an etched layer formed under the photomask layer The object to be treated of the Ti layer is subjected to a plasma having a fluorine compound-containing etching gas at a pressure of 4 Pa or less in the chamber, and the first plasma treatment project for etching the Ti layer by plasma of CF ₄ and Af gas is used. And after the end of the first plasma treatment project, the second plasma treatment project for dry cleaning is carried out by introducing the plasma of the cleaning gas into the treatment chamber into the plasma chamber of the NF ₃ and the Ar gas, in the second plasma treatment. In the treatment, the deposit of the Ti compound produced by the first plasma treatment project is removed. The plasma etching method according to claim 1, wherein the first plasma processing project and the second plasma processing project are alternately performed. The plasma etching method according to claim 1, wherein the cleaning gas used in the second plasma treatment project further contains a gas of CF ₄ or oxygen. The plasma etching method according to claim 1, wherein the pressure in the chamber in the second plasma treatment is 6.7 Pa or less. A control program, characterized in that: operating on a computer, when implemented, controlling a plasma processing device to perform electrical etching as recited in any one of claims 1 to 4. Engraving method. A computer memory medium is a control program for memorizing actions on a computer, wherein the control program, when implemented, controls plasma etching as described in any one of claims 1 to 4. The plasma processing apparatus used in the method. A plasma etching apparatus comprising: a plasma supply source for generating a plasma; and a processing container for treating a processing chamber for etching the object to be processed by the plasma, and the processing container; The support body on which the object to be processed is placed, the exhaust means for decompressing the inside of the processing container, and the gas supply means for supplying gas into the processing container, and the control are applied to the first to fourth items of the patent scope A control unit for a plasma etching method according to any one of the preceding claims.