KR20090020925A - Cleaning methods for semiconductor manufacturing apparatus - Google Patents

Abstract

A cleaning methods for a semiconductor manufacturing apparatus is provided to increase removal rate of particles with minimizing damage of electrode by applying high frequency power and DC bias to electrode in supplying cleaning gas inside a chamber. Cleaning gas is supplied inside a chamber(201) including electrodes(207) in order to wash a semiconductor equipment. High frequency power and direct-current bias are applied at the electrode and particles(210) adhered to the electrode are removed. The cleaning gas is supplied to the inside of the chamber through the holes of the electrode. The high frequency power is applied to the frequency of 40 - 200 MHz. The direct-current bias is applied into changeably selected fixed voltage in the range of -50 ~ -500V. The cleaning gas is one selected in the group consisting of the gas containing chlorine, the gas containing boron, the gas containing carbon and fluorine and combinations using the same.

Description

Cleaning methods for semiconductor manufacturing apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning semiconductor equipment, and more particularly, to a method for cleaning semiconductor equipment used for deposition and etching of thin films containing metal components.

The manufacturing process of a semiconductor device requires a number of thin film formation processes and etching processes. In particular, a process of forming a metal thin film or etching a metal film is called a metal process, and typically, the metal process is performed at a high temperature.

The technique using a reaction chamber capable of generating plasma has the advantage of performing the metal process at a relatively low temperature. According to the above technique, while introducing a reaction gas or an etching gas into the reaction chamber on which the wafer is mounted, generating a plasma by applying high frequency power to an electrode located inside or outside the reaction chamber to generate a chemical reaction on the wafer. It is common.

However, when the metal process is performed using the reaction chamber, by-products generated from the chemical reaction are adsorbed on the inner wall of the reaction chamber in the form of polymer particles. In particular, in the case of a reaction chamber having a showerhead having a distribution function of a reaction gas or an etching gas and an electrode function for generating plasma, the polymer particles can be easily adsorbed to the showerhead. The adsorbed polymer particles may be a contaminant in a subsequent manufacturing process, and may block holes that are passages of a reaction gas or an etching gas in the showerhead and prevent the subsequent process from proceeding.

One method commonly used to solve the polymer particle problem is to periodically wet clean the reaction chamber. However, such a wet cleaning requires a long cleaning time and may be a major factor in lowering the operation efficiency of the reaction chamber.

In order to increase the period of the wet cleaning, it is generally used to remove the polymer particles by an in-situ dry cleaning method. In the case of the in-situ dry cleaning method, plasma is generated by supplying a cleaning gas into the reaction chamber and applying high frequency power. The plasma converts the nonvolatile polymer particles into volatile products by reacting with the polymer particles attached to the showerhead. The volatile product can be easily discharged to the outside of the reaction chamber through the gas exhaust unit.

However, in the case of polymer particles containing a large amount of metal such as cobalt (Co), tungsten (W), or titanium (Ti), the process conditions necessary for the dry cleaning process mainly contain silicon (Si) or aluminum (Al). This can be different from one common polymer particle.

Specifically, in order to remove polymer particles containing metals such as cobalt (Co), tungsten (W), molybdenum (Mo), titanium (Ti), or nickel (Ni), cleaning with a high energy plasma is required. . To this end, when the temperature of the shower head is raised to a level corresponding to the high energy, the time required for raising the temperature of the shower head may be increased, thereby increasing the cleaning time. In addition, when the energy of the plasma is increased by heating the shower head to a high temperature, a problem may occur due to a very wide distribution of energy of the plasma. For example, besides the removal of the polymer particles by reaction with the high temperature plasma, side effects may occur in which the showerhead itself is corroded by some plasma with excessively high energy produced in a significant proportion.

The technical problem to be achieved by the present invention is to improve the problems of the prior art, in cleaning the reaction chamber provided with a shower head, to remove the polymer particles containing a metal component attached to the shower head at a high speed Damage to the showerhead is to provide an in-situ cleaning method which can be minimized.

The present invention provides a method of cleaning a chamber used for forming and etching thin films containing metal components. The cleaning gas is supplied into the chamber provided with the electrode. In addition to applying high frequency power to the electrode, a DC bias is further applied to remove particles attached to the electrode.

In another embodiment, the electrode may include holes for supplying the cleaning gas into the chamber.

As another embodiment, the high frequency power may be applied at a frequency of 40 to 200 MHz.

As another embodiment, the DC bias may be applied at a predetermined voltage that is variably selected in the range of -50 to -500V.

As another embodiment, the cleaning gas may be one selected from the group consisting of a gas containing chlorine, a gas containing boron, a gas containing carbon and fluorine, and combinations thereof.

In another embodiment, the pressure of the chamber may be 50 mTorr to 350 mTorr.

In another embodiment, the electrode may be maintained at a temperature of 200 ℃ to 400 ℃.

In another embodiment, the polymer particle may include one selected from the group consisting of cobalt (Co), tungsten (W), molybdenum (Mo), titanium (Ti), nickel (Ni), and combinations thereof. have.

In another embodiment, the nonvolatile particles are reacted with the cleaning gas charged and accelerated by the high frequency power and the direct current bias to convert into volatile reaction products, and the reaction products are discharged out of the chamber. The particles can be removed.

According to the present invention, a method of cleaning a chamber used for deposition and etching of a thin film containing a metal component is provided. The cleaning gas is supplied to the inside of the chamber, high frequency power is applied to the electrodes mounted inside the chamber, and DC bias is applied. As a result, the cleaning gas is converted into charged particles having high kinetic energy controlled by the DC bias, and reacts with particles attached to the electrode. As a result, the removal rate of the particles can be greatly increased while minimizing damage to the electrode.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed contents are thorough and complete, and that the spirit of the present invention to those skilled in the art will fully convey. In the drawings, the thickness of structures is exaggerated for clarity. Portions denoted by like reference numerals denote like elements throughout the specification.

1 is a cross-sectional view of a reaction chamber according to the present invention.

Referring to FIG. 1, the reaction chamber 101 according to the embodiment of the present invention may be a plasma processing apparatus. For example, the reaction chamber 101 may be formed using physical vapor deposition (PVD) technology, chemical vapor deposition (CVD) technology, or atomic layer deposition (ALD) technology. It may be to form a thin film on a semiconductor substrate. The thin film may be formed of a thin film of one metal selected from the group consisting of cobalt (Co), tungsten (W), molybdenum (Mo), titanium (Ti), nickel (Ni), and combinations thereof. The oxide film, the nitride film, or the silicide films may be formed. In another example, the reaction chamber 101 may be used to etch a predetermined region of the metal film or the like on a semiconductor substrate by using a dry etching technique.

The reaction chamber 101 may be made of a conductive material such as metal. The reaction chamber 101 may be grounded. The reaction chamber 101 may be heated by a heater (not shown). A susceptor 105 supporting the wafer 103 may be installed at the lower portion of the reaction chamber 101.

An electrode 107 may be positioned above the inside of the reaction chamber 101. The electrode 107 may be a showerhead of a plasma chamber. The electrode 107 may be made of a metal such as aluminum or stainless steel. The surface of the electrode 107 may be coated with another metallic material such as nickel (Ni). In this case, the reaction chamber 101 and the electrode 107 may be insulated from each other by a predetermined insulating member.

On the other hand, the electrode 107 may be provided with a heating unit (not shown). In addition, the electrode 107 may include a plurality of holes 109. Reaction gases and cleaning gases may be supplied into the reaction chamber 101 through the holes 109. To this end, a gas supply unit 111 may be connected to the electrode 107.

On the other hand, the gas exhaust unit 113 may be connected to the other side of the reaction chamber 101. The gas exhaust unit 113 may include a vacuum system for discharging the reaction by-product gas and the residual gas from the reaction chamber 101. As a result, the internal pressure of the reaction chamber 101 may be maintained at a predetermined pressure required for the reaction process or the cleaning process by the gas supply unit 111 and the gas exhaust unit 113.

The high frequency power source 115 and the DC power source 117 may be connected to the electrode 107 in parallel. A high frequency matcher 119 may be installed in the supply line of the high frequency power source 115 to allow the high frequency power to be optimally applied to the electrode 109. The high frequency power may be applied as a frequency of 40 to 200 MHz. If the frequency is less than 40MHz, the plasma generation efficiency is lowered, if the frequency is greater than 200MHz may cause a burden due to the addition of the relevant equipment. The high frequency power may be applied at a power of 100 to 1000W.

A negative DC bias may be additionally applied to the electrode 107 to which the high frequency power is applied using the DC power supply 117. The DC bias may be applied at a predetermined voltage that is variably selected in the range of -50 to -500V.

2 is a cross-sectional view schematically showing the reaction chamber to explain the cleaning method according to the present invention. 3 is a process flow chart for explaining the cleaning method of the reaction chamber according to the present invention.

2 and 3, as a preceding step, a predetermined thin film forming process or a predetermined etching process may be performed on a wafer (not shown) mounted on the reaction chamber 201. The reaction by-product generated during the thin film formation process or the etching process may be attached to the inside of the reaction chamber 201. The reaction products may be attached to the surface of the electrode 207 located above the reaction chamber 201 to form particles 210. The particles 210 may be polymers containing cobalt (Co), tungsten (W), molybdenum (Mo), titanium (Ti), nickel (Ni), or the like.

In the preparation step S301, the wafer on which the predetermined preceding step is completed may be removed from the reaction chamber 201. Alternatively, removing the wafer from the reaction chamber 201 may be omitted. Alternatively, a dummy wafer may be mounted in the reaction chamber after removing the wafer.

In the heating step S303, the electrode 207 may be heated to maintain a predetermined temperature. If the temperature of the electrode 207 is too low, the removal rate of the particles 210 may be too slow. On the other hand, if the temperature of the electrode 207 is too high, the time for heating may be long, and thus the operation efficiency of the reaction chamber 201 may be lowered. In addition, when the temperature of the electrode 207 is too high, the kinetic energy of the cleaning gas heated to a high temperature while passing through the holes 209 located in the electrode 207 may increase too much. In this case, the energy of the plasma generated by the high energy cleaning gas discharged by the high frequency power is too high, which may cause other problems. For example, in addition to cleaning the particles 210, the high energy plasma corrodes the inner wall of the reaction chamber 201 and the electrode 207 to reduce the durability of the reaction chamber 201. Can be born. Preferably, the temperature of the electrode 207 may be 200 ℃ to 400 ℃.

Meanwhile, the internal temperature of the reaction chamber 201 except for the surface of the electrode 207 may be 0 ° C to 100 ° C. For example, when the temperature of the electrode 207 is maintained at 250 ° C. in the absence of a separate heating to the reaction chamber 201, the internal temperature of the reaction chamber 201 may be about 50 ° C. FIG.

In the cleaning gas supplying step (S305), the cleaning gas may be supplied into the reaction chamber 201 at a flow rate of 100 sccm to 2000 sccm. The cleaning gas may be heated to 250 ° C. while passing through the holes of the electrode 207 and supplied into the reaction chamber 201. In this case, the pressure of the reaction chamber 201 may be adjusted by adjusting the gas supply unit 211 and the gas exhaust unit 213 to adjust the supply flow rate of the cleaning gas and the flow rate of the exhaust gas. Preferably, the pressure of the reaction chamber 201 may be maintained at a predetermined pressure in the range of 50 mTorr to 350 mTorr.

The cleaning gas may be one selected from the group consisting of a gas containing chlorine, a gas containing boron, a gas containing carbon and fluorine, and combinations thereof. Examples of the chlorine-containing gas include chlorine gas (Cl ₂ ) or chlorine trifluoride (ClF ₃ ). Examples of the gas containing boron include boron trichloride (BCl ₃ ) or boron trifluoride (BF ₃ ). Examples of the gas containing carbon and fluorine include methane trifluoride (CHF ₃ ) or methane tetrafluoride (CF ₄ ).

In the high frequency discharge step S307, high frequency power may be applied to the electrode 207 through the high frequency power source 215. Plasma may be generated from the cleaning gas by discharging the periphery of the electrode 207 with the high frequency power. The plasma may include charged particles 212 generated by ionizing the cleaning gas. The charged particles 212 may be cations of molecules generated by decomposition of the cleaning gas or the cleaning gas. When the temperature of the electrode 207 is maintained below 400 ° C., the energy of the plasma is not large enough to react with the particles 210 made of a metal component such as cobalt (Co). As a result, substantial cleaning may not proceed in the high frequency discharge step S307.

The DC bias applying step (S309) is a step where substantial cleaning of the reaction chamber 201 is performed. In the DC bias application step (S309), to increase the responsiveness of the plasma, a DC bias using the DC power source 217 connected in parallel to the high frequency power source 215 to the electrode 207 to which the high frequency power is applied. Can be applied. The DC bias may be applied simultaneously with the high frequency power. The direct current bias may be a negative bias. Specifically, the DC bias may be applied at -50V to -500V. In this case, a strong electric field 214 is generated around the electrode 207 to accelerate the charged particles 212 generated from the cleaning gas toward the electrode 207. Accordingly, the charged particles 212 traveling toward the electrode 207 may obtain high energy and may easily react with the particles 210 attached to the electrode 207.

Meanwhile, by adjusting the DC bias to a predetermined voltage, the charged particles 212 may be precisely controlled to have energy within a predetermined range. That is, the voltage of the DC bias may be adjusted such that the charged particles 212 have energy necessary for reacting with the particles 210 but not excessive energy enough to cause side reactions. As a result, the reaction for removing the particles 210 is activated by applying the DC bias of the predetermined voltage to the electrode 207, but the side effects of the charged particles 212 corroding the electrode 207 are Can be greatly reduced.

When the particles 210 react with the accelerated charged particles 212, the non-volatile particles 210 react with the charged particles 212 containing chlorine or fluorine to volatile reaction products. Can be switched to. The DC bias applying step (S309) may be performed for a predetermined time so that the particles 210 of 5 μs to 500 μs may be sufficiently etched in response to the charged particles 212. For example, when the main component of the particles 210 is cobalt silicide (CoSi ₂ ), an internal temperature of the reaction chamber 207 is 250 ° C., and the direct current bias is -300V, the particles 210 are formed. The removal rate in response to the charged particles 212 may be about 2000 kW per minute.

In the evacuation step S311, the supply of the cleaning gas may be stopped and the DC bias and the high frequency power may be cut off. In this case, the reaction by-products generated in the DC bias application step S309 and the residues of the cleaning gas may be discharged to the outside of the reaction chamber 201 through the gas exhaust unit 213. Alternatively, the discharge of the reaction byproduct and the like may be partially performed in the DC bias applying step (S309). In the case of the exhaust step (S311), it is possible to facilitate the discharge of the reaction by-products and the residue by purging the reaction chamber 201 with an inert gas. Alternatively, purging the inert gas can be omitted.

In a subsequent step (S313), another wafer may be mounted in the reaction chamber 201. Subsequently, a predetermined subsequent process may be performed, such as forming a thin film on the other wafer or etching the other wafer.

Experimental Example

Table 1 shows the change in the DC current measured according to the change in the DC voltage applied to the electrode according to an embodiment of the present invention.

Actual value of DC current according to change of DC voltage applied to electrode DC voltage applied (V) Actual value of direct current (mA) -120 0.8 -210 2.1 -290 4.2 -360 9.0 -380 16.3

The experiment of Table 1 was carried out as follows. A predetermined cleaning gas was injected into the reaction chamber and the exhaust flow rate was adjusted to maintain the pressure in the reaction chamber at 60 mTorr. In this case, a mixed gas of Cl ₂ , BCl ₃ , and CHF ₃ was used as the cleaning gas. The temperature of the electrode was maintained at 250 ° C.

In order to generate plasma from the cleaning gas, high frequency power having a 100 MHz frequency was applied to the electrode at a power of 500 W using a high frequency power source. Subsequently, a DC power supply was operated to apply a DC bias to the electrode. In this case, while applying the DC bias divided into five voltages of -100V to -380V, respectively, the current flowing through the DC power supply was measured according to each voltage.

Referring to Table 1, the measurement of the DC current was consistently increased while the voltage of the DC bias increased from -120V to -380V. In particular, when the voltage of the DC bias becomes greater than -300V, the measured value of the DC current has rapidly increased.

The increase in the measurement of the direct current with the increase of the voltage of the direct current bias is caused by the charged particles generated from the cleaning gas by the high frequency power being accelerated by the electric field formed on the surface of the electrode by the direct current bias. will be. This is because the speed at which the charged particles accelerate toward the electrode and the frequency at which the accelerated charged particles collide with the electrode may increase. As a result, it can be inferred that by increasing the energy of the charged particles as the DC bias is applied to the electrode, the removal rate of the particles attached to the electrode can be greatly increased.

Although the present invention has been described in detail with reference to preferred embodiments of the present invention, the present invention is not limited to the above-described embodiments and may be modified in various other forms within the spirit of the present invention.

1 is a cross-sectional view of a reaction chamber according to the present invention.

2 is a cross-sectional view schematically showing the reaction chamber to explain the cleaning method according to the present invention.

3 is a process flow chart for explaining the cleaning method of the reaction chamber according to the present invention.

Claims (9)

Supplying a cleaning gas into the chamber provided with the electrode, And removing particles attached to the electrode by applying a high frequency power and a direct current bias to the electrode. The method of claim 1, And the electrode includes holes for supplying the cleaning gas to the inside of the chamber. The method of claim 1, The high frequency power is a cleaning method for a semiconductor device, characterized in that applied at a frequency of 40 to 200 MHz. The method of claim 1, The direct current bias is a cleaning method for a semiconductor device, characterized in that applied to a predetermined voltage variably selected in the range of -50 to -500V. The method of claim 1, The cleaning gas is one selected from the group consisting of a gas containing chlorine, a gas containing boron, a gas containing carbon and fluorine, and combinations thereof. The method of claim 1, The pressure of the chamber is 50 mTorr to 350 mTorr characterized in that the cleaning method for semiconductor equipment. The method of claim 1, The electrode is a cleaning method of a semiconductor device, characterized in that maintained at a temperature of 200 ℃ to 400 ℃. The method of claim 1, The polymer particle may include one selected from the group consisting of cobalt (Co), tungsten (W), molybdenum (Mo), titanium (Ti), nickel (Ni), and combinations thereof. Cleaning method. The method of claim 1, Removing the particles converts the nonvolatile particles into the volatile reaction product by reacting with the cleaning gas charged and accelerated by the high frequency power and the direct current bias, and discharging the reaction product out of the chamber. Method for cleaning a semiconductor device, characterized in that.

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