JP2004047500A - Plasma processing apparatus and method of initializing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing device which is efficiently set up and is shifted to another process, and is capable of preventing generation of particles from occurring. <P>SOLUTION: A semiconductor wafer mount 100 is equipped with a susceptor 153 of, for instance, AlN or the like and a dielectric member 180 formed of, for instance, SiO<SB>2</SB>or the like and is shaped so as to cover the entire susceptor 153. The dielectric member 180 is subjected to plasma processing for a certain time without mounting semiconductor wafer 1 so as to enable the plasma processing device to be efficiently set up, and shifted to another process, and to prevent generation of particles from occurring. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plasma processing apparatus and a method for initializing the plasma processing apparatus. In particular, the plasma processing apparatus can be efficiently initialized after cleaning the plasma processing apparatus, performing another process, or preventing generation of particles. The present invention relates to a plasma processing apparatus and an initialization method thereof.
[0002]
[Prior art]
2. Description of the Related Art In the manufacture of semiconductor devices, the density and integration have been increasing recently. For this reason, design rules are becoming stricter, for example, the line width of a gate wiring pattern and the like is further reduced, and the aspect ratio of a contact hole, which is a connection portion between a lower semiconductor device and an upper wiring layer, is increasing.
[0003]
As described above, for manufacturing a semiconductor device designed according to strict design rules, management of the manufacturing process is important. For example, in an etching process, it is necessary to surely etch a contact hole having a fine pattern and a high aspect ratio. For this reason, it is indispensable to control the etching rate and reliably form a desired pattern.
[0004]
However, in a plasma processing apparatus that performs etching, particularly a plasma processing apparatus that uses inductively-coupled plasma (hereinafter referred to as ICP), since no potential is applied to a chamber made of, for example, quartz, the etched material is deposited on the inner wall of the chamber. Easy to adhere as foreign matter. The foreign matter adhering to the inner wall of the chamber or the like affects the plasma state at the time of etching, and becomes a factor of changing the etching rate.
[0005]
In particular, various processes may be performed in order to respond to various requirements accompanying the progress of semiconductor devices. As an example, an oxide film (eg, SiO 2) formed by oxidizing or altering the bottom surface of the contact hole before embedding a material such as tungsten in the contact hole. ₂ ) Must be etched. However, when etching a conductive material other than the oxide film that is usually etched, for example, a material such as Poly-Si, W, WSi, or CoSi, if the oxide film is etched again thereafter, a phenomenon called a memory effect occurs.
[0006]
The memory effect is the following phenomenon. For example, when a film made of a metal material such as CoSi is etched, the etched material adheres to a chamber made of a quartz material and its inner wall, and electrons and ions generated in the plasma are grounded via the attached matter. As a result, the plasma becomes unstable and is affected by the plasma state. Therefore, immediately after that, even if etching is performed under the same conditions using an oxide film as a target, the plasma is unstable, and the etching rate does not reach a steady state. In other words, when a film other than the film that is normally etched is etched, a material different from the one that normally adheres to the inside of the chamber or its inner wall adheres, thereby changing the impedance with respect to the plasma, and thereby affecting the plasma state, and thus the memory effect is reduced. Will be triggered.
[0007]
FIG. 18 is a schematic sectional view showing an example of the semiconductor wafer mounting section 10 in a conventional plasma processing apparatus. As shown in FIG. 18, the semiconductor wafer mounting section 10 has a guide ring 80 and a susceptor 153a.
[0008]
The susceptor 153a is made of, for example, AlN. The guide ring 80 is made of, for example, SiO ₂ The upper surface is located above the susceptor 153a, and is configured to guide the outer periphery of the semiconductor wafer 1 to be mounted at an appropriate position. .
[0009]
A plasma processing apparatus having such a semiconductor wafer mounting unit 10 is, for example, usually made of SiO2. ₂ When the semiconductor wafer of the film is being etched, the surface of the semiconductor wafer whose surface is covered with Poly-Si is etched on the way, and then the surface is made of SiO. ₂ When the wafer is etched, the etching rate decreases. In this case, for example, SiO ₂ Unless five semiconductor wafers are processed (corresponding to an etching time of, for example, 150 seconds), a normal etching rate may not be recovered.
[0010]
This is because the plasma state, which had been attenuated due to the scattering of Poly-Si Si and adhering to the inner wall surface of the chamber, was changed to SiO 2 ₂ It is considered that the oxide state is deposited again inside the chamber to some extent due to the etching of several semiconductor wafers, and the plasma state returns to the original steady state.
[0011]
Therefore, in order to return the etching rate to a steady state, etching using a dummy wafer is performed. However, preparing a dummy wafer requires time, labor, and cost, which is not preferable in that production and work efficiency are deteriorated.
[0012]
Further, the deposits on the inner wall of the chamber are, for example, ClF. ₃ The cleaning using gas is difficult to remove by etching, and even if the cleaning is performed, the etching must be performed using a certain number of dummy wafers in order for the apparatus to return to a steady state.
[0013]
Furthermore, when a plurality of semiconductor wafers are etched, the operation time of the apparatus becomes longer, so that the deposits attached to the inner wall of the chamber become thicker and peel off due to film stress, and ions and radicals in the processing gas cause Particles may be generated as particles due to the attachments being subjected to stress such as reduction and erosion and being peeled off.
[0014]
In such a case, it is also known that the generation of particles can be suppressed by performing a plasma treatment using a wafer whose surface is covered with an oxide film as a dummy wafer and attaching an oxide to the inner wall of the chamber. However, this work is also not preferable from the viewpoint of production and work efficiency.
[0015]
Further, the guide ring 80 arranged around the susceptor 153a is configured so that the upper surface is located above the susceptor 153a. There is also a problem that the in-plane uniformity of the processing is impaired.
[0016]
Conventionally, an O-ring or a flat or L-shaped gasket having both flat surfaces has been used to seal a dielectric wall, particularly a bell jar type dielectric wall, and a processing chamber.
[0017]
However, when an O-ring is used, it is necessary to protect a portion other than the contact surface of the O-ring to prevent damage. In addition, when a flat or L-shaped gasket is used, there is a problem that a sufficient surface pressure cannot be secured on the sealing surface, and vacuum leakage is likely to occur.
[0018]
Further, conventionally, when a processing gas is introduced into a processing chamber, the processing gas is introduced from the ceiling using a so-called shower head having a structure in which a plurality of gas introduction holes are formed in the ceiling.
[0019]
However, in the showerhead structure, the distance between the wafer and the gas introduction hole is limited according to the structure of the processing apparatus, and the gas distribution at the outer peripheral portion of the wafer changes. There was a problem of impairing the performance.
[0020]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems of the conventional plasma processing apparatus and its initialization method, and an object of the present invention is to start up the apparatus efficiently and to etch materials other than oxide films. It is an object of the present invention to provide a new and improved plasma processing apparatus and an initialization method thereof, which can appropriately perform the above processing and can prevent generation of particles.
[0021]
Still another object of the present invention is to provide a new and improved plasma processing apparatus capable of preventing metal contamination based on the material composition of members constituting the apparatus such as a mounting table in the processing apparatus. It is.
[0022]
Further, another object of the present invention is to improve in-plane uniformity of plasma processing such as film formation and etching by making gas flow uniform on a wafer and uniformly distributing plasma over the entire processing surface. It is an object of the present invention to provide a plasma processing apparatus having a new and improved gas introduction structure capable of performing the above-described steps.
[0023]
[Means for Solving the Problems]
According to the present invention, there is provided a plasma processing apparatus configured to excite an induction plasma into a processing chamber through a dielectric wall. There is provided a plasma processing apparatus provided with a dielectric member capable of detachably covering at least a mounting surface, for example, quartz.
[0024]
According to this configuration, when troubles such as generation of particles occur during processing in the plasma processing apparatus, the inside of the chamber is cleaned by wet cleaning or the like, the maintenance is performed regularly, and the etching target is removed. Etching a dielectric member placed on a mounting table in plasma, for example, when shifting to another process such as when shifting from metal etching to oxide film etching, and when returning the inside of the chamber to an initial state. Therefore, it is possible to efficiently initialize the inside of the chamber of the plasma processing apparatus without using a dummy wafer, and since the mounting surface of the mounting table is covered with a dielectric member, even if the material forming the mounting table is metal or the like. Prevents contamination of the chamber and workpieces by this metal, even if it contains impurities can do.
[0025]
A guide ring for guiding the object to be processed may be formed around the mounting surface of the dielectric member, and the surface of the guide ring is formed at a position lower than the processing surface of the object to be processed. May be. The dielectric member may have a concave shape that can be put on the mounting table. Further, the dielectric member may be configured as an assembly including a mounting surface portion and a guide ring portion which can be separated from each other.
[0026]
According to this configuration, the object to be processed and the dielectric member can be accurately placed, the plasma can be made uniform on the processing surface of the object to be processed, and the production and consumption of the dielectric member can be achieved. Exchange at the time becomes easy.
[0027]
According to yet another aspect of the present invention, a plasma processing apparatus configured to excite an induced plasma into a processing chamber through a dielectric wall, for example, a bell jar-shaped dielectric wall, comprises: Between them, there is provided a plasma processing apparatus characterized by disposing a flat gasket made of a fluoroelastomer material and having at least one row of annular projections formed on both surfaces thereof.
[0028]
According to such a configuration, it is possible to protect the entire sealing surface and secure an appropriate surface pressure, so that it is possible to provide a more airtight plasma processing apparatus.
[0029]
Further, according to another aspect of the present invention, in a plasma processing apparatus configured to perform plasma processing on an object to be processed disposed in a processing chamber, a gap between a side wall and a ceiling of the processing chamber is provided. A plasma processing apparatus is provided, wherein a gas introduction ring having a plurality of gas ejection holes opening upward from the processing chamber is provided.
[0030]
The gas ejection hole may be opened in an upward tapered surface, and the gas ejection hole may be opened toward one point of the processing chamber. Further, the plasma processing apparatus excites induction plasma into the processing chamber through a bell jar type dielectric wall, and the ceiling may be a bell jar type dielectric wall.
[0031]
According to such a configuration, it is possible to uniformly eject gas from a side surface of the processing chamber toward a predetermined position of the processing chamber, for example, toward the center. As a result, the gas flow becomes uniform on the wafer, the plasma is also generated uniformly, and the in-plane uniformity of plasma processing such as film formation and etching can be improved.
[0032]
Further, a dielectric member configured to excite the induced plasma into the processing chamber through the dielectric wall and capable of removably covering at least a mounting surface of a mounting table for mounting an object to be processed in the processing chamber. A method for initializing a plasma processing apparatus, comprising: exciting plasma in a processing chamber for a predetermined time while exposing a dielectric member at the time of initialization of the plasma processing apparatus; An initialization method for a plasma processing apparatus that can be generated is provided. The initialization of the plasma processing apparatus is performed when shifting to another process, when starting up the plasma processing apparatus, or when generating particles. At the time of initialization, plasma of Ar gas may be excited in the processing chamber to generate plasma stably.
[0033]
According to the above method, initialization of the plasma processing apparatus can be efficiently performed in terms of operation rate, and it is effective in preventing generation of particles, so that a highly reliable process can be performed.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a plasma processing apparatus and an initialization method thereof according to the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted.
[0035]
(First Embodiment)
FIG. 1 is a schematic view showing a plasma processing apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the plasma processing apparatus 150 is an etching apparatus that removes an oxide film or a film of another material on a semiconductor wafer, and can employ an inductively coupled plasma (ICP) method.
[0036]
This device 150 has a substantially cylindrical chamber 151 and a substantially cylindrical bell jar 152. The bell jar 152 is provided above the chamber 151 in a gas-tight manner via a gasket 179 described later. The bell jar 152 is formed of a dielectric material such as quartz or a ceramic material.
[0037]
A susceptor 153 is provided in the chamber 151. The susceptor 153 is for horizontally supporting a semiconductor wafer (hereinafter simply referred to as a wafer) 1 which is an object to be processed. The dielectric member 180 according to the present embodiment is disposed on the upper surface of the susceptor 153, and its detailed structure will be described later. Although the dielectric member 180 is supported by the susceptor 153, a shaft 184 that stands up from the bottom of the chamber 151 is provided to support the dielectric member 180 as shown in FIG. Is also good. One or more shafts 184 may be provided. For example, three or four shafts 184 may be provided to support a portion of the dielectric member 180 extending beyond the susceptor 153, and the shafts 184 may be arranged at equal intervals in the circumferential direction of the dielectric member 180.
[0038]
The support member 154 has a substantially cylindrical shape, and supports the susceptor 153. The heater 156 is embedded in the susceptor 153 to heat the wafer 1. The power supply 175 supplies power to the heater 156 via the power supply connection line 177.
[0039]
The coil 157 is wound around the bell jar 152 as an antenna member. The high frequency power supply 158 is connected to the coil 157 via the matching unit 159. The high-frequency power supply 158 can generate high-frequency power having a frequency of, for example, 450 kHz to 60 MHz (preferably 450 kHz to 13.56 MHz).
[0040]
Here, the configuration of the upper part of the bell jar 152 will be described. FIG. 3 is a schematic sectional view showing the configuration of the upper part of the bell jar 152, and FIG. 4 is an enlarged view of a portion P shown in FIG. As shown in FIG. 3, a counter electrode 201 for the susceptor 153 is provided at an upper portion outside the bell jar 152. The counter electrode 201 is formed of Al or the like, and is provided between the bell electrode 152 and the bell jar 152 via a cap 203 and a spacer ring 205 for preventing the buffer from the bell jar 152 disposed at the center. The cap 203 and the spacer ring 205 are formed of a resin such as Teflon (registered trademark) and press the bell jar 152 so as to hermetically close it.
[0041]
The counter electrode 201 is connected to an Al cover 207 provided thereon, and the cover 207 is connected to an Al sheath cover 209 that covers the side surface of the bell jar 152. The counter electrode 201 is grounded via the cover 207 and the sheath cover 209.
[0042]
A matching device 159 is provided further above the cover 207, and is electrically connected to the coil 157 via a portion P in FIG. As shown in FIG. 4, the P portion includes an electrode 211 connected to the matching unit 159, an electrode 213 connected to the electrode 211, an electrode 215 connected to the electrode 213, and an electrode connected to the electrode 215 by a screw 219. 217, and each electrode is detachable. Further, the electrode 217 is connected to the clip 221, and the clip 221 sandwiches the coil 157, so that the matching unit 159 and the coil 157 are electrically connected.
[0043]
The clip 221 only needs to have a function of electrically connecting the electrode 217 and the coil 157, and the connection portion 223 may be connected to the coil 157 by the screw 225 as shown in FIG. The electrodes 213 and 215 are made of copper coated with silver. The outsides of the electrodes 213 and 215 are covered with a cover 227 made of a heat-resistant resin such as an amide resin, and further covered with a cover 229 made of Al. As described above, by supplying high frequency power from the high frequency power supply 158 to the coil 157 via the matching unit 159, an induction electromagnetic field is formed in the bell jar 152.
[0044]
The gas supply mechanism 160 includes an Ar supply source 161, which supplies Ar for etching the surface of the semiconductor wafer, and an H source for reducing oxides of the metal material. ₂ H to supply ₂ It has a source 162. The gas lines 163 and 164 are connected to gas supply sources 161 and 162, respectively. Valves 165, 178 and a mass flow controller 166 are provided for each line.
[0045]
The gas introduction ring 167 is provided annularly between the bell jar 152 and the ceiling of the side wall of the chamber 151, and supplies the processing gas in the direction indicated by the arrow, that is, toward the center (α point) of the space 155 in the bell jar 152. It can be ejected, and is airtightly fixed to the upper part of the side wall of the chamber 151 via a gasket 179 with bolts or the like. A plurality of gas introduction holes 167a for ejecting the processing gas toward the substantially central portion of the space 155 are formed on the inner peripheral side wall surface of the gas introduction ring 167. The gas introduction hole 167a is arranged at an angle of 1/2 of the number of turns (height of the coil) of the induction coil disposed outside the bell jar 152 at an angle at which the processing gas is ejected toward the center of the space 155. I have. Further, since the gas introduction holes 167a are arranged at equal intervals, the processing gas can be uniformly injected into the space 155 of the bell jar 152.
The number of the gas introduction holes 167a is not limited thereto, and the number and the ejection angle are adjusted so as to form a uniform flow according to the size of the apparatus. In the present embodiment, twenty are formed. Further, the uniform ejection angle of the gas introduction holes 167a can be arbitrarily determined by the molding angle, and may be an angle (fixed) toward the center of the space 155, that is, the upper part of the semiconductor wafer.
[0046]
As shown in FIG. 6, the gas introduction ring 167 is provided with a gas passage 167d communicating with the annular groove 167b, and gas lines 163 and 164 are connected to the gas passage 167d. The gas from the gas lines 163 and 164 is injected into the gas introduction ring 167 through the gas passage 167d, and the etching gas is introduced toward the center of the space 155 through the gas introduction hole 167a.
[0047]
As shown in FIG. 6, the gas introduction ring 167 can be configured such that a side surface 167c on the space portion 155 side is formed vertically, and a gas introduction hole 167a is opened in the vertical side surface 167c. However, in such a configuration, a velocity difference occurs between the gas flow A ejected from the upper portion of the hole and the gas flow B ejected from the lower portion of the hole, so that when the processing gas is ejected from the gas introduction hole 167a, Since a turbulent flow (spiral flow) is formed near the outlet of the gas introduction hole 167a, gas cannot be uniformly introduced into the space 155.
[0048]
Therefore, as shown in FIG. 7, a tapered surface 167f is formed on the side surface 167c of the gas introduction ring 167 on the space portion 155 side, and the gas introduction hole 167a formed upward is formed substantially perpendicular to the tapered surface 167f. The gas flow spouted from the upper part of the hole is formed by opening the hole and further adjusting the angle so that the direction of the gas introduction hole 167a is at a height position that is half the number of turns (height of the coil) of the induction coil. The speed difference between A and the gas flow B ejected from the lower part of the hole is reduced, and the gas can be uniformly introduced into the chamber. In addition, it is preferable that the vicinity of the outlet of the gas introduction hole 167a on the space portion 155 side is chamfered like the outlet 167g so as to reduce the resistance at the time of gas ejection.
[0049]
Next, the configuration of the gas passage 167d for introducing gas into the groove 167b in the gas introduction ring 167 will be described with reference to FIG. FIGS. 8A and 8B are diagrams showing the configuration of the gas passage 167d. FIG. 8A is a schematic view from above, and FIG. 8B is a schematic view from the Q direction in FIG. (c) is a schematic view of the RR section of FIG.
[0050]
As shown in FIG. 8, the gas introduction ring 167 is provided with a gas passage 167d for introducing gas into the internal groove 167b. As shown in FIG. 8B, an inlet of a gas passage 167d is provided outside the gas introduction ring 167. A horizontal hole 167h is provided in the upper part of the connection between the gas passage 167d and the groove 167b, as shown in FIGS. The gas introduced from the gas passage 167d passes through the horizontal hole 167h and is introduced into the groove 167b. With this configuration, the gas easily flows in the circumferential direction of the groove 167b, and when the plurality of gas introduction holes 167a are formed in the gas introduction ring 167, the gas ejected toward the space 155 is made more uniform. effective.
[0051]
The connection between the side wall of the chamber 151 and the side wall of the bell jar 152 is airtightly connected via a gasket 179 in order to maintain the degree of vacuum. FIG. 9 is a sectional view of a gasket according to one embodiment of the present invention. As shown in FIG. 9, the gasket 179 is provided between the sealing surface of the bell jar 152 and the upper sealing surface of the gas introduction ring 167. Thereby, airtightness is maintained, and the sealing surface of the bell jar 152 can be protected to prevent breakage. Further, the gasket 179 may be made of, for example, a fluorine-based elastomer material for the purpose of further improving the airtightness. May be formed. The protrusion 179a may not be provided on the lower surface of the gasket 179, and a plurality of protrusions 179a such as two protrusions 179a may be provided on the upper surface of the gasket 179.
[0052]
An exhaust device 169 including a vacuum pump is connected to the exhaust pipe 168. A part of the bottom wall of the chamber 151 is open, and a concave exhaust part 182 is airtightly connected to this opening. The exhaust pipe 168 is connected to a side opening of the exhaust part 182. A support member 154 that supports the susceptor 153 is provided at the bottom of the exhaust part 182. By operating the exhaust device 169, the inside of the chamber 151 and the bell jar 152 can be depressurized to a predetermined degree of vacuum through the exhaust unit 182 and the exhaust pipe 168.
[0053]
Further, a gate valve 170 is provided on a side wall of the chamber 151. The wafer 1 is transferred between an adjacent load lock chamber (not shown) with the gate valve 170 opened. The electrode 173 buried in the susceptor 153 is connected to a high-frequency power supply 171 via a matching unit 172 so that a bias can be applied.
[0054]
The processing operation in the plasma processing apparatus configured as described above will be described. First, the gate valve 170 is opened, the wafer 1 is inserted into the chamber 151, the lifter pins 181a are lifted by the lifter pin lifting / lowering drive unit 181b of the lifter pin drive mechanism 181, and the wafer 1 is received by the lifter pins 181a. After that, the lifter pins 181a are lowered, and the wafer 1 is placed on the susceptor 153. Thereafter, the gate valve 170 is closed, and the chamber 151 and the bell jar 152 are evacuated by the exhaust device 169 to a predetermined reduced pressure state. Subsequently, the Ar supply source 161 and H ₂ Ar gas and H are supplied from the supply source 162 into the chamber 151. ₂ While supplying gas, high-frequency power is supplied from the high-frequency power supply 158 to the coil 157 to form an induction electromagnetic field in the space 155 in the bell jar 152.
[0055]
Plasma is generated in the space 155 in the bell jar 152 by the induced electromagnetic field, and the plasma removes, for example, an oxide film on the surface of the wafer 1 by etching. For example, H ₂ When gas is used, electric power may be supplied from the power supply 175 to the heater 156 as necessary to heat the heater 156. Further, a bias voltage may be applied to the susceptor 153 from the high frequency power supply 171.
[0056]
As an example of the processing conditions at this time, for example, the pressure is 0.1 to 13.3 Pa, preferably 0.1 to 2.7 Pa, the wafer temperature is 100 to 500 ° C., the gas flow rate is, 0.03 L / min, preferably 0.005 to 0.015 L / min, H ₂ 0 to 0.06 L / min, preferably 0 to 0.03 L / min, the frequency of the high frequency power supply 158 of the plasma processing apparatus 150 is 450 kHz to 60 MHz, preferably 450 kHz to 13.56 MHz, and the bias voltage is -20 to -200 V (0 ５００500 W). By treating with plasma under such conditions for about 30 seconds, for example, SiO ₂ Is removed by about 1 to 10 nm.
[0057]
FIG. 2 is a schematic cross-sectional view illustrating the semiconductor wafer mounting unit 100 according to the first embodiment. As shown in FIG. 2, the semiconductor wafer mounting section 100 has a susceptor 153 and a dielectric member 180.
[0058]
The susceptor 153 is made of, for example, AlN, Al ₂ O ₃ , SiC material and the like. The dielectric member 180 is made of, for example, SiO. ₂ , Al ₂ O ₃ , AlN, or Si ₃ N ₄ For example, it is made of a material that maintains dielectric during plasma processing. The dielectric member 180 can be placed on the susceptor 153. The dielectric member 180 in the present embodiment uses quartz as an example.
[0059]
The dielectric member 180 on the upper surface of the susceptor 153 has a thickness t1. If the thickness is too thin, it is difficult to process, and the durability is poor. , Preferably 0.5 to 1 mm.
[0060]
At the center of the upper surface of the dielectric member 180 that covers the outer peripheral portion of the susceptor 153, a step t2 that is concave downward is provided so as to guide the outer periphery of the wafer 1 and mount the wafer 1 at an appropriate position. ing. Since the thickness of the wafer 1 is about 0.7 mm, the step t2 is, for example, about 0.5 to 3 mm, preferably 1 to 3 mm, and more preferably the same level as that of the wafer.
[0061]
The dielectric member 180 has an outer diameter larger than that of the susceptor 153, and is provided with an outer edge portion 180a that protrudes outside the susceptor 153 when the dielectric member 180 is placed on the susceptor 153. Further, the dielectric member 180 has a convex portion 180n that is convex downward at the center thereof, and is accommodated in a concave portion 153n that is concave upward and provided on the susceptor 153.
[0062]
Specifically, for example, the concave portion 153n of the susceptor 153 is formed as a counterbore as shown in FIG. 2, and the convex portion 180n of the dielectric member 180 contacts the concave portion 153n of the susceptor 153. The lower surface of the outer edge 180a of the member 180 may be brought into contact. Thus, the dielectric member 180 can be stably mounted on the susceptor 153 without slipping off the susceptor 153.
[0063]
In the plasma processing apparatus 150 having such a semiconductor wafer mounting portion 100, plasma processing has conventionally been performed using a dummy wafer in order to initialize the memory effect or prevent generation of particles. Instead, for example, the etching of the dielectric member 180 is performed while the wafer 1 is not loaded while the wafer 1 is carried in and out. This is called after-process processing.
[0064]
Actually, the output of the high frequency power supply 158 for ICP is 200 to 1000 W (preferably 200 to 700 W), the output of the power supply 171 for bias voltage is 100 to 500 W (preferably 400 W), the frequency is 13.56 MHz, and the pressure is 13.56 MHz. It is preferable to use only Ar gas at about 0.1 to 1.33 Pa (preferably 0.67 Pa), and the flow rate of the Ar gas is 0.001 to 0.06 L / min (preferably 0.001 to 0. (Susceptor temperature: 03 L / min or 0.038 L / min) The susceptor temperature is −20 to 500 ° C., preferably 200 ° C. (Ar gas and H ₂ When a gas mixture is used, the susceptor temperature is 500 ° C.). The processing time is 5 to 30 seconds, for example, preferably about 10 seconds. By etching the dielectric member under such processing conditions and attaching the dielectric member to the inner wall surface of the bell jar, the memory effect and the generation of particles can be prevented.
[0065]
Here, the mechanism of the generation of particles and the memory effect will be described with reference to FIGS. FIG. 10 is an elemental composition analysis diagram by SEM-EDX (scanning electron microscope with an energy dispersive X-ray spectrometer), FIG. 11 is a conceptual diagram of particle generation, and FIGS. FIG.
[0066]
FIGS. 10A, 10B and 10C respectively show Si, bell jar 152 side wall deposits and SiO ₂ FIG. 4 is an element composition analysis diagram of FIG. As shown in FIG. 10, Si, bell jar 152 side wall deposit, SiO ₂ Are 100: 0, 49:46 and 34:66, respectively. Therefore, the side wall deposit of the bell jar 152 is assumed to be SiO because the Si element and the O element are contained at about 1: 1.
[0067]
As shown in FIG. 11A, the SiO deposited on the side wall of the bell jar 152 is formed in the space 155 in the bell jar 152 by etching. ₂ If hydrogen exists in the processing gas, H ⁺ Is considered to be reduced to SiO.
[0068]
As shown in FIG. 11B, when a large amount of SiO is deposited due to the processing of a large number of wafers, the film becomes a film like a deposit 315. As shown in FIG. 11C, when the Si-rich SiO film has a certain thickness, the Si-rich SiO film peels off like a deposit 317 due to stress, and becomes a particle. Therefore, as described above, the after-process treatment for suppressing the generation of particles is performed using SiO 2. ₂ Is preferably performed only with an Ar gas that does not reduce the hydrogen.
[0069]
FIGS. 12 and 13 show the etching amount when the processing is performed under the same etching conditions, respectively. As shown in FIG. ₂ Are etched, and COSi is applied to each of the second semiconductor wafers. ₂ , Poly-Si is etched, the third ₂ Etching causes a memory effect, which is different from the initial etching amount.
[0070]
This memory effect is considered to be caused by the fact that when a different material is etched, a different material adheres to the inner wall of the chamber, and the generated plasma becomes unstable. When the memory effect occurs as described above, if the above-described after-process is performed before the next process (here, the etching of the fourth semiconductor wafer), as shown in FIG. ₂ , Or the amount of etching before the etching of Poly-Si. This is considered to be because the inner wall of the chamber is again covered with the original material and the plasma state is stabilized. Thus, the after-process processing has the effect of eliminating the memory effect.
[0071]
When the dielectric member 180 is processed under the above-described conditions for the after-process, the following results are obtained for the plasma processing time required to return to the steady state etching rate.
[0072]
Other than the oxide film, for example, Poly-Si (polysilicon) or CoSi ₂ To prevent the memory effect after etching conductive materials such as (cobalt silicon, cobalt silicide), it is necessary to initialize for about 150 seconds after wet cleaning using chemicals when maintaining the inside of the chamber. It took about 300 seconds to process particles and about 1500 seconds to prevent particles. By etching the dielectric member for several tens of seconds, the inside of the chamber can be returned to a steady state, and optimal etching can be performed. It becomes possible.
[0073]
In particular, Ar gas and H used as processing gas ₂ When the etching of the silicon oxide film is repeatedly performed by the plasma of the gas mixture of the gas, the sputtered SiOx adheres to the inner wall of the processing container or the surface of the member in the processing container, and the processing gas H ₂ The gas dissociates from the plasma and becomes H ⁺ And H ^* Is generated and eroded. Therefore, for example, SiO ₂ The dielectric member 180 made of plasma or the like is subjected to plasma treatment to newly add SiO ₂ By covering with a dielectric material, etc., it is possible to make the surface state in which particles are hardly generated, and to suppress the generation of particles. In the plasma processing for preventing particles, it is preferable to use Ar gas as a processing gas.
[0074]
In addition, if the above processing time is to be performed using a dummy wafer, a processing time of about 30 seconds per sheet is used as a countermeasure against a memory effect, initialization after wet cleaning using a chemical or the like, and prevention of particles. , Which correspond to about 5, 10, and 50 sheets, respectively. According to the plasma processing apparatus and the initialization method of the present embodiment for processing the dielectric member 180 in this manner, measures for the memory effect, initialization after wet cleaning using a chemical, etc., and particle prevention are provided. Therefore, there is no need to prepare a dummy wafer, which has the effect of improving work and production efficiency. The dielectric member 180 can be replaced when it is consumed after etching.
[0075]
(Second embodiment)
FIG. 14 is a schematic cross-sectional view illustrating a semiconductor wafer mounting unit 500 according to the second embodiment. As shown in FIG. 14, the semiconductor wafer mounting portion 500 can be used in place of the semiconductor wafer mounting portion 100 in the plasma processing apparatus 150. The same components and functions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
[0076]
The susceptor 153a has a convex center and is made of, for example, AlN. The dielectric member 580 is made of, for example, SiO. ₂ , Al ₂ O ₃ , AlN, or Si ₃ N ₄ For example, the susceptor 153a is made of a material that maintains dielectric during plasma processing, and has a shape that covers the entire susceptor 153a. The dielectric member 580 on the upper surface of the susceptor 153a has a thickness t1. If it is too thin, it is difficult to process, the durability is inferior. Preferably it can be 1-3 mm.
[0077]
A step t2 is provided on the upper surface of the dielectric member 580 that covers the outer peripheral portion of the susceptor 153a, and is configured to guide the outer periphery of the wafer 1 and mount the wafer 1 at an appropriate position. Since the thickness of the wafer 1 is about 0.7 mm, the step t2 is, for example, about 0.5 to 3 mm, preferably 1 to 3 mm, and more preferably the same level as the thickness of the wafer.
[0078]
In the plasma processing apparatus 150 having such a semiconductor wafer mounting section 500, the wafer 1 is mounted instead of the processing conventionally performed using a dummy wafer in order to initialize the memory effect and the wet processing, or to prevent generation of particles. The dielectric member 580 is etched without being placed.
[0079]
The etching conditions and the required time are the same as those in the first embodiment, but since the dielectric member 580 is configured to cover the susceptor 153a, it is not necessary to support the dielectric member 580 with a shaft. Also, it is preferable to use an Ar gas as a processing gas during plasma processing for preventing generation of particles.
[0080]
(Third embodiment)
FIG. 15 is a schematic sectional view showing a semiconductor wafer mounting section 600 according to the third embodiment. As shown in FIG. 15, the semiconductor wafer mounting section 600 can be used in place of the semiconductor wafer mounting section 100 in the plasma processing apparatus 150. The same reference numerals are given to the same configurations and functions as those in the first and second embodiments, and the description is omitted.
[0081]
The semiconductor wafer mounting section 600 has a susceptor 153a and dielectric members 680 and 682. The dielectric members 680 and 682 are made of, for example, SiO. ₂ , Al ₂ O ₃ , AlN, or Si ₃ N ₄ For example, the susceptor 153a is made of a material that maintains dielectric during plasma processing, and has a shape that covers the entire susceptor 153a.
[0082]
The dielectric member 680 has a thickness t1. If it is too thin, it is difficult to process, and the durability is inferior. If it is thick, the cost is high, for example, about 0.5 to 5 mm, preferably 1 to 3 mm. can do.
[0083]
A step t3 is provided on the upper surface of the dielectric member 682 that covers the outer peripheral portion of the susceptor 153a. The step t3 is configured to guide the outer periphery of the dielectric member 680 and the wafer 1 to be mounted at an appropriate position. Since the thickness of the dielectric member 680 is about 0.5 to 3 mm and the thickness of the wafer 1 is about 0.7 mm, the step t3 is, for example, about 1 to 4 mm, preferably at the same level as the surface of the wafer. It is good to be the surface that becomes.
[0084]
In the plasma processing apparatus 150 equipped with such a semiconductor wafer mounting part 600, the wafer 1 is replaced with the wafer effect instead of the processing conventionally performed using a dummy wafer in order to initialize the memory effect and the wet processing, or to prevent the generation of particles. The dielectric member 680 is etched without being placed.
[0085]
The etching conditions and the required time are the same as those of the first and second embodiments. However, since the dielectric member is an assembly of two parts, the processing at the time of manufacturing is smaller than that of the dielectric member 580. Therefore, there is an effect that replacement when exhausted by etching becomes easy. Also, it is preferable to use an Ar gas as a processing gas during plasma processing for preventing generation of particles.
[0086]
(Fourth embodiment)
FIG. 16 is a schematic sectional view showing a semiconductor wafer mounting part 700 according to the fourth embodiment. As shown in FIG. 16, the semiconductor wafer mounting section 700 can be used in place of the semiconductor wafer mounting section 100 in the plasma processing apparatus 150. The same reference numerals are given to the same configurations and functions as those in the first, second, and third embodiments, and description thereof will be omitted.
[0087]
The semiconductor wafer mounting section 700 has a susceptor 153a and dielectric members 780 and 782. The dielectric members 780 and 782 are made of, for example, SiO. ₂ , Al ₂ O ₃ , AlN, or Si ₃ N ₄ For example, the susceptor 153a is made of a material that maintains dielectric during plasma processing, and has a shape that covers the entire susceptor 153a.
[0088]
The upper surface portion of the susceptor 153a of the dielectric member 780 has a thickness t1, and if it is too thin, it is difficult to process, and the durability is poor. can do.
[0089]
A step t2 is provided on the upper surface of the dielectric member 780 that covers the outer peripheral portion of the susceptor 153a, and is configured to guide the outer periphery of the wafer 1 and mount the wafer 1 at an appropriate position. Since the thickness of the wafer 1 is about 0.7 mm, the step t2 is, for example, about 0.5 to 3 mm, and preferably has a surface at the same level as the wafer surface.
[0090]
In the plasma processing apparatus 150 equipped with such a semiconductor wafer mounting section 700, the wafer 1 is replaced with a wafer 1 instead of the processing conventionally performed using a dummy wafer in order to initialize the memory effect and wet processing, or to prevent generation of particles. The dielectric member 780 is etched without being placed.
[0091]
The etching conditions and the required time are the same as those of the previous embodiment. However, since the dielectric member is an assembly of two parts, it is easier to replace when consumed by etching than the dielectric member 580. In addition, there is an effect that similar effects can be obtained with a smaller number of materials as compared with the dielectric members according to the second and third embodiments. At the time of plasma processing for preventing generation of particles, it is preferable to use Ar gas as a processing gas.
[0092]
(Fifth embodiment)
FIG. 17 is a schematic sectional view showing a semiconductor wafer mounting section 800 according to the fifth embodiment. As shown in FIG. 17, the semiconductor wafer mounting section 800 can be used in place of the semiconductor wafer mounting section 100 in the plasma processing apparatus 150. The same components and functions as those in the first, second, third, and fourth embodiments are denoted by the same reference numerals, and description thereof is omitted.
[0093]
The semiconductor wafer mounting section 800 has a cylindrical susceptor 153b and a dielectric member 880. The dielectric member 880 is made of, for example, SiO. ₂ , Al ₂ O ₃ , AlN, or Si ₃ N ₄ For example, the susceptor 153b is made of a material that maintains dielectric during plasma processing, and has a shape that covers the entire susceptor 153b. The susceptor 153b is partially different from the susceptors 153 and 153a in accordance with the shape of the dielectric member 880.
[0094]
The upper surface portion of the susceptor 153b of the dielectric member 880 has a thickness t1, and if it is too thin, it is difficult to process, the durability is inferior. can do.
[0095]
A step t2 is provided on the upper surface of the dielectric member 880 that covers the outer peripheral portion of the susceptor 153b, and is configured to guide the outer periphery of the wafer 1 and mount the wafer 1 at an appropriate position. Since the thickness of the wafer 1 is about 0.7 mm, the step t2 is preferably, for example, about 0.5 to 3 mm, and is preferably a surface of the same level as the wafer.
[0096]
In the plasma processing apparatus 150 equipped with such a semiconductor wafer mounting section 800, the wafer 1 is replaced with a wafer 1 instead of the processing conventionally performed using a dummy wafer in order to initialize the memory effect and the wet processing or to prevent the generation of particles. The dielectric member 880 is etched without being placed.
[0097]
The etching conditions and the required time are the same as those of the first embodiment, but the dielectric member is simplified compared to the dielectric members according to the first, second, third and fourth embodiments. By adopting such a shape, replacement when it is consumed by etching is facilitated, the same effect can be obtained with a small amount of material, and it is more preferable when used in a plasma processing apparatus for mass-producing semiconductor devices. Also, it is preferable to use an Ar gas as a processing gas during plasma processing for preventing generation of particles.
[0098]
The preferred embodiments of the plasma processing apparatus and the initialization method according to the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person skilled in the art can conceive various changes or modifications within the scope of the technical idea described in the claims, and those changes naturally fall within the technical scope of the present invention. It is understood to belong.
[0099]
For example, the shape and material of the dielectric member are not limited to such examples. Different shapes and materials may be used as long as similar effects can be obtained. Further, the processing conditions and the processing time are specific to each plasma processing apparatus, and do not limit the present invention.
[0100]
【The invention's effect】
As described above, according to the present invention, a new and improved plasma processing apparatus capable of efficiently starting up an apparatus and shifting to another process and preventing generation of particles, and a plasma processing apparatus therefor. An initialization method can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a plasma processing apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic sectional view showing a semiconductor wafer mounting portion 100 according to the first embodiment of the present invention.
FIG. 3 is a schematic sectional view showing a configuration of an upper portion of a bell jar 152.
FIG. 4 is an enlarged view of a portion P in FIG.
FIG. 5 is a plan view of a connection portion 223.
FIG. 6 is a schematic sectional view of a gas introduction ring according to the first embodiment of the present invention.
FIG. 7 is a schematic sectional view of a gas introduction ring according to another embodiment of the present invention.
FIG. 8 is a diagram showing a configuration of a gas passage 167d.
FIG. 9 is a sectional view of a gasket according to one embodiment of the present invention.
FIG. 10 is an element composition analysis diagram by SEM-EDX (scanning electron microscope with an energy dispersive X-ray spectrometer).
FIG. 11 is a conceptual diagram of particle generation.
FIG. 12 is a diagram showing a change in an etching amount due to a memory effect.
FIG. 13 is a diagram showing a change in an etching amount due to a memory effect.
FIG. 14 is a schematic sectional view showing a semiconductor wafer mounting section 500 according to a second embodiment of the present invention.
FIG. 15 is a schematic sectional view showing a semiconductor wafer mounting section 600 according to a third embodiment of the present invention.
FIG. 16 is a schematic sectional view showing a semiconductor wafer mounting section 700 according to a fourth embodiment of the present invention.
FIG. 17 is a schematic sectional view showing a semiconductor wafer mounting section 800 according to a fifth embodiment of the present invention.
FIG. 18 is a schematic sectional view showing an example of a semiconductor wafer mounting section 10 in a conventional plasma processing apparatus.
[Explanation of symbols]
100 Semiconductor wafer mounting part
150 Plasma processing equipment
153 susceptor
180 dielectric member

Claims (15)

In a plasma processing apparatus configured to excite an induction plasma into a processing chamber through a dielectric wall,
A plasma processing apparatus, comprising: a dielectric member capable of detachably covering at least a mounting surface of a mounting table on which an object to be processed is mounted in the processing chamber. 2. The plasma processing apparatus according to claim 1, wherein a guide ring for guiding an object to be processed is formed around a mounting surface of the dielectric member. 3. The plasma processing apparatus according to claim 2, wherein a surface of the guide ring is formed at a position lower than a processing surface of the object to be processed. 4. The plasma processing apparatus according to claim 1, wherein said dielectric member has a concave shape capable of covering an upper part of said mounting table. 5. The plasma processing apparatus according to claim 1, wherein the dielectric member is configured as an assembly including a mounting surface portion and a guide ring portion which can be separated from each other. . 6. The plasma processing apparatus according to claim 1, wherein said dielectric member is quartz. In a plasma processing apparatus configured to excite an induction plasma into a processing chamber through a dielectric wall,
A plasma processing apparatus, wherein a flat gasket made of a fluorine-based elastomer material and having at least one row of annular projections formed on both surfaces thereof is disposed between the dielectric wall and the processing chamber. The plasma processing apparatus according to claim 7, wherein the dielectric wall has a bell jar shape. In a plasma processing apparatus configured to perform plasma processing on an object to be processed disposed in a processing chamber,
A plasma processing apparatus, characterized in that a gas introduction ring having a plurality of gas ejection holes opening upward from the processing chamber is disposed between a side wall and a ceiling of the processing chamber. 10. The plasma processing apparatus according to claim 9, wherein the gas ejection hole is formed in an upward tapered surface. 11. The plasma processing apparatus according to claim 9, wherein the gas ejection hole is opened toward one point of the processing chamber. 10. The plasma processing apparatus for exciting induction plasma into the processing chamber through a bell jar type dielectric wall, wherein the ceiling is the bell jar type dielectric wall. 12. The plasma processing apparatus according to any one of 10 and 11. A dielectric member configured to excite the induction plasma into the processing chamber through the dielectric wall and capable of detachably covering at least a mounting surface of a mounting table for mounting an object to be processed in the processing chamber. A method for initializing a plasma processing apparatus comprising:
A method for initializing a plasma processing apparatus, comprising: exciting plasma in the processing chamber for a predetermined time while exposing the dielectric member when the plasma processing apparatus is initialized. 14. The method according to claim 13, wherein the initialization of the plasma processing apparatus is performed when the process is shifted to another process, when the plasma processing apparatus is started, or when particles are generated. 15. The method of claim 13, wherein the initialization of the plasma processing apparatus is performed by converting Ar gas introduced into the processing chamber into plasma.

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