JP2012049376A - Plasma processing apparatus and plasma processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem of conventional plasma processing that gas flow distribution and reaction product flow distribution in the processing chamber cannot be controlled according to change in plasma conditions, controllable ranges of gas flow distribution and reaction product flow distribution are narrow, and gas flow distribution and reaction product flow distribution cannot be changed with high accuracy between steps in step etching.SOLUTION: A first etching gas supply means and a second etching gas supply means are provided and the etching gas supply means are adjusted respectively. The second etching gas supply means is installed on the periphery of a wafer, and etching gas flow and reaction product flow in the processing chamber are controlled.

Description

  The present invention relates to a plasma processing apparatus and a plasma processing method, and more particularly to a plasma processing apparatus and a plasma processing method suitable for performing an etching process on a material to be processed such as a semiconductor element substrate using plasma.

  In the semiconductor manufacturing process, dry etching using plasma is generally performed. Various types of plasma processing apparatuses for performing dry etching are used.

  In general, a plasma processing apparatus includes a vacuum processing chamber, a gas supply device connected to the vacuum processing chamber, an evacuation system for maintaining the pressure in the vacuum processing chamber at a desired value, an electrode on which a wafer as a processing object is placed, a vacuum processing It comprises plasma generating means for generating plasma in the room. The processing gas supplied from the shower plate or the like into the vacuum processing chamber by the plasma generating means is changed to a plasma state, whereby the wafer held by the wafer mounting electrode is etched.

  In recent years, with the improvement in the degree of integration of semiconductor devices, fine processing, that is, improvement in processing accuracy is required, and in-plane uniformity of etching rate or in-plane uniformity of CD value (Critical Dimension) in etching shape, etc. Improvement is required. In addition, the material to be etched is also changed from a single layer film to a multilayer film, and multi-step etching that changes etching conditions during the processing of each layer film or film is frequently used. This is because the factors that affect the in-plane uniformity of the etching rate and the etching shape are different in the material characteristics constituting each layer film. The uniformity of the in-plane etching rate of the material to be etched is susceptible to the following effects. Plasma density distribution, radical distribution, gas flow distribution, in-plane temperature distribution during etching of the material to be etched, reaction product distribution due to etching reaction, temperature setting of processing chamber side wall, etc. The influence of these distributions depends on the material characteristics of each layer film. In the case of plasma etching, the conditions of the etching process (for example, plasma excitation power, type of gas used, gas mixture ratio, gas pressure, bias RF power) It is necessary to optimize the temperature setting of the electrode or reactor wall etc. according to the material of each film layer. Therefore, it is difficult to obtain highly accurate in-plane uniformity of the etching rate and the etching shape (for example, CD) at the time when the etching of the multilayer film is completed. Further, in recent semiconductor processing, with the miniaturization, uniformity of etching characteristics is required on the order of nanometers or sub-nanometers. For this reason, it is necessary to control the gas flow distribution and the reaction product flow distribution in the processing chamber so as to be optimized in each processing step.

  As an etching gas supply means in a conventional plasma processing apparatus, as described in Non-Patent Document 1, an etching gas is supplied only from an etching gas supply means from the upper surface of a processing chamber provided above the center of a wafer. It is common. Furthermore, Patent Document 1 discloses a technique for introducing an etching gas from a plurality of locations on the upper surface of a processing chamber as a technique for improving the in-plane uniformity of ions and radicals in plasma (Japanese Patent Laid-Open No. 2003-260260). Sho 62-290885).

JP-A-62-290885

First semiconductor manufacturing equipment (Maeda, Industrial Research Committee, 1999)

  In the etching gas supply means in the conventional plasma processing apparatus, the etching gas supply means from the upper surface of the processing chamber is used to control the gas flow distribution and reaction product flow distribution in the processing chamber. One that introduces an etching gas is known.

  However, even if the etching gas is supplied from the upper surface of the processing chamber, the range in which the gas flow distribution and the reaction product flow distribution in the processing chamber can be controlled is extremely small. This is because when the etching gas is supplied only from the etching gas supply means from the upper surface of the processing chamber, the concentration of the etching gas and the reaction product concentration are often high in the central portion of the wafer and low in the outer peripheral portion. It is difficult to form a gas flow or reaction product flow that changes the flow rate or reverses the distribution. Furthermore, depending on the type of each film deposited on the wafer, the processing gas type, processing gas pressure, and plasma distribution change greatly, and accordingly, the optimal gas flow distribution and reaction product flow distribution for each film layer also change greatly. It is necessary to widen these control ranges. Even in an apparatus that introduces an etching gas from a plurality of locations on the upper surface of the processing chamber, since the wafer and the upper surface of the processing chamber are separated, it is difficult to control the gas flow distribution and reaction product flow distribution in the vicinity of the wafer, and the control range is extremely large. There is a problem of being narrow.

  In addition, when etching a laminated film in which multiple materials are deposited on a wafer, etching is performed sequentially under the optimum conditions (processing gas type, processing gas pressure, plasma distribution, wafer processing temperature, etc.) for each film material. It is necessary to perform processing. When a desired etching process is performed, each stage of the etching process (hereinafter referred to as a step) is sequentially performed according to a predetermined order. The etching process conditions are different, and the optimum gas flow distribution and reaction product flow distribution for each film during the plasma processing change greatly. When the etching gas is supplied from the upper surface of the processing chamber as in the prior art, the range in which the gas flow and the reaction product flow in the processing chamber can be controlled is extremely small. Even in an apparatus that introduces etching gas from multiple locations on the upper surface of the processing chamber, it is difficult to control the gas flow distribution and reaction product flow distribution in the vicinity of the wafer because the wafer and the upper surface of the processing chamber are separated from each other. Very narrow. The etching gas flow distribution and reaction product flow distribution cannot be changed with high accuracy so as to be optimal for each deposited film between the steps.

  On the other hand, as the wafer diameter becomes as large as Φ300 mm, the plasma distribution, reaction product distribution, etc. within the wafer surface tend to be non-uniform. As a countermeasure, a method for controlling the gas flow distribution and the reaction product flow in the plane so that the etching characteristics are uniform is required instead of making the gas flow distribution and the reaction product flow distribution uniform in the plane. Has been. In other words, highly accurate gas flow control and reaction product flow control in the vicinity of the wafer are required.

  Therefore, in the present invention, the gas flow distribution and the reaction product flow distribution can be controlled in accordance with changes in the processing gas type, processing pressure, plasma distribution, wafer temperature distribution, etc. An object of the present invention is to provide a plasma processing apparatus and a plasma processing method capable of widening the range of product flow distribution.

  Further, when plasma processing is performed on the laminated film on the wafer, the gas flow distribution and the reaction product flow are accurately performed between the steps in the step processing in which the plasma processing steps are sequentially performed according to a predetermined order. The purpose is to change the distribution.

  In the present invention, the gas flow distribution and reaction product flow in the processing chamber are controlled in accordance with changes in the processing gas type, processing pressure, plasma distribution, wafer temperature distribution, etc., and the range of the gas flow distribution that can be further controlled, the reaction product In order to widen the range of the flow distribution, the first etching gas supply means and the second etching gas supply means are provided, and the gas flow distribution in the processing chamber is adjusted by adjusting the etching gas introduced from each supply means, The reaction product flow distribution can be controlled with high accuracy.

  The first etching gas supply means includes one or more types of gas cylinders for supplying one or more types of etching gas and a gas corresponding to the one or more types of gas cylinders for introducing the one or more types of etching gas. A pipe, a gas valve, one or more types of gas flow controllers corresponding to the one or more types of etching gas for controlling the supply amount of the one or more types of etching gas, and the one or more types of supply amounts are controlled. In addition to the first etching gas supply means, the second etching gas supply means supplies one or more types of etching gases. One or more types of gas cylinders for performing the above and one or more types of gas cylinders for introducing the one or more types of etching gas. A pipe, a gas valve, one or more types of gas flow controllers corresponding to the one or more types of etching gas for controlling the supply amount of the one or more types of etching gas, and the one or more types of supply amounts are controlled. And a gas pipe for mixing and introducing the etching gas into the processing chamber.

  With the above configuration, each gas type, gas flow rate, and gas mixture ratio of the etching gas introduced from each etching gas supply means can be controlled. The second etching gas supply means may be connected to a susceptor provided around the electrode for mounting the material to be processed so that the etching gas can be introduced from the periphery of the material to be processed. The gas flow distribution and reaction product flow distribution in the processing chamber can be controlled with high accuracy and in a wider control range.

  Further, when etching the laminated film on the wafer by the above means, even in the step etching in which each step of the etching process is sequentially advanced according to a predetermined order, the processing chamber is highly accurate between each step. It is possible to change the gas flow distribution and the reaction product flow distribution.

  In the plasma processing apparatus and the processing method of the present invention, the gas flow that can control and further control the gas flow distribution and reaction product flow in the processing chamber in accordance with changes in the processing gas type, processing pressure, plasma distribution, wafer temperature distribution, and the like. There is an effect that the range of distribution and the range of reaction product flow distribution can be widened. In the present invention, the first etching gas supply means and the second etching gas supply means are provided, and the etching gas introduced from each supply means can be adjusted, and the gas flow distribution in the processing chamber, the reaction product flow There is an effect that the distribution can be controlled.

  The first etching gas supply means includes one or more types of gas cylinders for supplying one or more types of etching gas and a gas corresponding to the one or more types of gas cylinders for introducing the one or more types of etching gas. A pipe, a gas valve, one or more types of gas flow controllers corresponding to the one or more types of etching gas for controlling the supply amount of the one or more types of etching gas, and the one or more types of supply amounts are controlled. In addition to the first etching gas supply means, the second etching gas supply means supplies one or more types of etching gases. One or more types of gas cylinders for performing the above and one or more types of gas cylinders for introducing the one or more types of etching gas. A pipe, a gas valve, one or more types of gas flow controllers corresponding to the one or more types of etching gas for controlling the supply amount of the one or more types of etching gas, and the one or more types of supply amounts are controlled. And a gas pipe for mixing and introducing the etching gas into the processing chamber. Thereby, there is an effect that each gas type, gas flow rate, and gas mixture ratio of the etching gas introduced from each etching gas supply means can be controlled. The second etching gas supply means may be connected to a susceptor provided around the electrode for mounting the material to be processed so that the etching gas can be introduced from the periphery of the material to be processed. There is an effect that the gas flow distribution and the reaction product flow distribution in the processing chamber can be controlled with high accuracy and in a wider control range.

  In the above-mentioned present invention, when etching the laminated film on the wafer, even in the step etching in which each step of the etching process is sequentially advanced according to a predetermined order, the processing chamber is highly accurate between the steps. It is possible to change the gas flow distribution and the reaction product flow distribution.

1 is a longitudinal sectional view of a microwave ECR etching apparatus that is an embodiment of the present invention. 1 is a longitudinal sectional view of a microwave ECR etching apparatus that is an embodiment of the present invention. The etching rate distribution in an Example. The sequence diagram explaining an example of the plasma processing method of this invention. 1 is a longitudinal sectional view of a microwave ECR etching apparatus that is an embodiment of the present invention. (A) (B) Arrangement | positioning drawing of the gas inlet applied to one Example of this invention. (A) (B) The perspective view of the gas inlet part applied to one Example of this invention.

Example 1
A microwave ECR (Electron Cyclotron Resonance) etching apparatus according to an embodiment of the present invention will be described below with reference to FIG. A processing chamber 104 is formed by installing a dielectric window 103 (for example, made of quartz) for enclosing an etching gas in the vacuum vessel 101 on the upper portion of the vacuum vessel 101 whose top is opened. In addition, a vacuum exhaust device (not shown) is connected to the vacuum vessel 101 via a vacuum exhaust port 106.

  A waveguide 107 (or an antenna) that radiates electromagnetic waves is provided above the dielectric window 103 in order to transmit power for generating plasma to the processing chamber 104. The electromagnetic wave transmitted to the waveguide 107 (or antenna) is oscillated from the electromagnetic wave generating power source 109. The frequency of the electromagnetic wave is not particularly limited, but a microwave of 2.45 GHz is used in this embodiment. A magnetic field generating coil 110 that forms a magnetic field is provided on the outer periphery of the processing chamber 104, and the electric power oscillated from the electromagnetic wave generation power source 109 is high in the processing chamber 104 due to the interaction with the formed magnetic field. Generate a density plasma.

  Further, a wafer mounting electrode 111 is provided below the vacuum vessel 101 so as to face the dielectric window 103. The wafer mounting electrode 111 has an electrode surface covered with a sprayed film (not shown), and a DC power supply 116 is connected through a high frequency filter 115. Further, a high frequency power supply 114 is connected to the wafer mounting power supply 111 via a matching circuit 113.

  The wafer 112 transferred into the processing chamber 104 is adsorbed on the wafer mounting electrode 111 by the electrostatic force of the DC voltage applied from the DC power supply 116, and after supplying a desired etching gas into the processing chamber 104, The inside of the vacuum chamber 101 is set to a predetermined pressure, and plasma is generated in the processing chamber 104. By applying a high frequency power from a high frequency power source 114 connected to the wafer mounting electrode 111, ions are drawn from the plasma into the wafer, and the wafer 112 is etched.

  Next, the etching gas supply means 120 and 130 in this embodiment will be described with reference to FIG. The first etching gas supply means 120 used in the plasma processing apparatus of this embodiment is supplied with a shower plate 102 (for example, made of quartz) for introducing the etching gas into the processing chamber 104 and the first etching gas. A pipe 121, a valve 122 for supplying a first etching gas, a gas flow rate controller 123 for controlling the supply amount of each gas in the first etching gas, a valve 124 for supplying each gas in the first etching gas, Each gas cylinder 125 is connected. In many cases, the shower plate 102 for introducing the etching gas is provided above the vacuum vessel 101, and in this embodiment, the shower plate 102 is installed immediately below the dielectric window 103. Each gas cylinder 125 is composed of one or more types of gas cylinders, and a mixed gas optimum for a material to be processed (hereinafter, referred to as “wafer” in the description of the embodiments) is introduced into the processing chamber 104 by a pipe 121. Supplied.

  The second etching gas supply means 130 is supplied with a gas introducing portion 136 for introducing an etching gas into the processing chamber 104 from the periphery of the wafer mounting electrode 111 under the vacuum vessel 101 and a second etching gas. A pipe 131 for supplying a second etching gas, a gas flow controller 133 for controlling the supply amount of each gas in the second etching gas, and a valve 134 for supplying each gas in the second etching gas. The gas cylinders 135 are connected. In this embodiment, a gas inlet 136 for introducing an etching gas is provided in a susceptor 105 (for example, made of quartz) installed around the wafer mounting electrode 111, and a pipe for supplying a second etching gas is provided. Connected. The second etching gas is composed of a mixed gas of three systems, the first system is a gas that promotes etching (for example, chlorine gas), and the second system is a gas that suppresses etching (for example, carbon tetrafluoride gas). ) The third system is an inert gas (eg, argon gas) that does not affect the etching. The etching gas introduced from the first etching gas supply means 120 has gas flow lines in the direction from the shower plate to the wafer 112 in the vicinity of the shower plate 102, but in the vicinity of the wafer 112 from the center of the wafer 112 to the wafer. 112 has gas flow lines in the outer circumferential direction. In the etching reaction of the wafer 112, an etching rate and an etching shape are determined by an etching gas atmosphere in the vicinity of the wafer 112.

  The second etching gas is directed from the gas introduction part 136 for introducing the second etching gas toward the center of the wafer 112 so as to influence the gas flow line in the vicinity of the wafer 112 of the first etching gas. Have a streamline heading. That is, as shown in FIG. 6A, the gas introduction unit 136 for introducing the second etching gas blows out the second etching gas from the outer periphery of the wafer in the direction substantially parallel to the wafer. Is desirable. Therefore, in this embodiment, a slit-like opening is provided on the entire circumference of the inner diameter portion of the susceptor 105. Further, as shown in FIG. 6B, the gas introduced from the slit-shaped opening is radiated by being inclined from the central direction, thereby preventing gas accumulation near the inside of the opening. May be.

  In this embodiment, as shown in FIG. 1, the gas introduction part 136 is provided in the susceptor 105. However, the same effect can be obtained if the susceptor 105 and the gas introduction part 136 are provided separately and around the wafer mounting electrode 111. Is obtained. In the first etching gas supply means 120 and the second etching gas supply means 130, the gas cylinders 125 and 135 are provided independently, but the piping from each gas cylinder is branched to supply the first etching gas. The means 120 may be connected to the means 130 for supplying the second etching gas. Furthermore, the pipe for supplying the second etching gas is not limited to three systems, and a plurality of gas pipes may be connected.

  An example of the gas introduction part 136 is shown in FIG. 7A as a perspective view thereof, but it is not necessary to provide slit-like openings all around unless the etching rate and the uniformity of the etching shape in the wafer are significantly reduced. One or more slit-shaped openings and one or more hole-shaped openings may be provided.

  Further, as shown in FIG. 2, a gas reservoir 201 for providing conductance may be provided in the susceptor connected to the second etching gas supply means 130. In this case, the second etching gas is provided at the opening of the susceptor. There is an effect that the etching gas introduced from the supply means 130 is uniformly ejected in the entire circumferential direction. As an example, a perspective view thereof is shown in FIG. The second etching gas supply means 130 does not need to be connected to the susceptor 105 from one place, and one or more connecting places may be provided. Also in this case, the uniformity of the etching gas introduced from the opening of the susceptor is improved, and the effect of improving the circumferential uniformity of the gas flow distribution and the reaction product flow distribution inside the processing chamber 104 is obtained.

  The material of the susceptor 105 is not limited to quartz material. For example, the same effect can be obtained with a ceramic material such as an alumina material. Furthermore, the susceptor 105 needs to form a flow path for flowing the etching gas introduced from the second etching gas supply means 130 therein. In order to form this flow path, the structure of the susceptor 105 has a plurality of components. Or a structure in which a plurality of components are bonded together.

  When the structure of the susceptor 105 is composed of a plurality of parts, there is an effect that the cost of the member can be reduced. In the case of a structure in which a plurality of parts are bonded together, the etching introduced from the second etching gas supply means 130 The effects of reducing gas leakage from the gas flow path and improving the circumferential uniformity of the gas introduced from the opening of the susceptor are obtained.

  In the embodiment of the present invention described above, the arrangement of the etching gas introduction holes of the shower plate 102 in the first etching gas supply means 120 is a concentric annular shape or a circular shape. Furthermore, the arrangement of the gas introduction part 136 in the second etching gas supply means 130 is also a concentric ring. The concentric circular or circular shape allows the etching gas flow distribution to be symmetric about the central axis with respect to the wafer 112. For example, the etching rate distribution in the wafer surface and the etching shape (including CD) are controlled. The effect is easy.

  Further, the position of the opening provided in the inner diameter portion so that the etching gas introduced from the second etching gas supply means 130 can be introduced from the inner diameter portion of the susceptor 105 is larger than the position of the outermost periphery of the wafer 112 in the radial direction. Further, by setting the position within 1 mm to 30 mm from the position of the outermost periphery of the wafer 112 in the radial direction, there is an effect that the etching gas flow distribution and the reaction product flow distribution in the processing chamber can be controlled with high accuracy. If the gas introduction part 136 of the second etching gas supply means 130 is, for example, 30 mm or more away from the wafer 112, the etching gas flow and reaction product flow in the vicinity of the wafer 112 cannot be controlled.

  When plasma processing is performed, each valve 124 of the first etching gas supply means is opened, and an etching gas (for example, chlorine gas, hydrogen bromide gas, tetrafluoromethane gas, methane trifluoride, methane trifluoride, difluoride methane, difluoride methane trifluoride, difluoromethane Fluorinated methane, argon gas, helium gas, oxygen gas, nitrogen gas, carbon dioxide, carbon monoxide, hydrogen, ammonia, propane octafluoride, nitrogen trifluoride, sulfur hexafluoride gas, methane gas, silicon tetrafluoride gas , Silicon tetrachloride gas, etc.) are supplied, and the respective gas flow rate controllers 123 are controlled so as to obtain a desired etching gas mixture ratio. Similarly, the second etching gas supply means 130 also opens the valves 134, and etching gas (for example, chlorine gas, hydrogen bromide gas, tetrafluoromethane gas, argon gas, helium gas, oxygen gas, nitrogen) from each gas cylinder 135. Gas, sulfur hexafluoride gas, methane gas, CHF3 gas, NF3 gas, SiF4 gas, SiCl4 gas, etc.) are supplied, and each gas flow rate controller 133 is controlled so as to obtain a desired etching gas mixture ratio.

  When only the first etching gas supply means 120 is provided as in the conventional plasma processing apparatus, it is difficult to control the gas flow and the reaction product flow inside the processing chamber 104 with high accuracy. In contrast, by providing the second etching gas supply means 130 as in the plasma processing apparatus of the present embodiment, the gas flow and reaction product flow inside the processing chamber 104 can be optimally controlled in each processing step. Can do. In addition, since the gas flow and reaction product flow inside the processing chamber can be controlled with high accuracy, the etching rate and etching shape distribution within the surface of the material to be etched can be controlled arbitrarily, such as a convex distribution or a concave distribution. It becomes.

  In this embodiment, the first and second etching gas supply means are two systems, but by providing a plurality of two or more etching gas supply means, etching in the wafer surface can be performed with higher accuracy. The rate and etching shape (including CD) can be controlled.

  Next, FIG. 3 shows an actual etching rate result. In the present embodiment, the material to be etched is a polysilicon film, and, for example, chlorine gas, tetrafluoromethane gas, or argon gas is used as an etching gas. A curve 301 indicates the distribution in the wafer surface of the etching rate when etching is performed using only the first etching gas supply unit 120, that is, uniformity. A curve 302 shows the in-wafer distribution of the etching rate when chlorine gas is introduced from the second etching gas supply means 130 and other etching gas is introduced from the first etching gas supply means 120. A curve 303 indicates an etching rate when tetrafluoromethane gas is introduced from the second etching gas supply means 130 and other etching gas, chlorine gas, and argon gas are introduced from the first etching gas supply means 120. The wafer in-plane distribution is shown.

  As indicated by a curve 301, when the etching gas is supplied using only the first etching gas supply means 120, the etching rate in the wafer surface has a substantially uniform distribution. On the other hand, as shown by the curve 302, when a gas (for example, chlorine gas) having a characteristic of promoting the etching rate in the etching rate performance is introduced from the outer periphery of the wafer, the etching rate at the outer peripheral portion of the wafer is increased. Furthermore, as shown by the curve 303, when a gas (for example, tetrafluoromethane gas) having a characteristic of suppressing the etching rate in the etching rate performance is introduced from the outer periphery of the wafer, the etching rate at the outer peripheral portion of the wafer is lowered. It can be seen that the uniformity of the etching rate within the wafer surface can be controlled by supplying the etching gas using the second etching gas supply means 130.

  In this embodiment, a desired etching gas can be introduced at a desired flow rate by using the second etching gas supply means 130, and the gas flow inside the processing chamber 104 can be arbitrarily controlled. Further, by arbitrarily controlling the gas flow inside the processing chamber 104, there is an effect that the reaction product flow inside the processing chamber 104 can also be controlled with high accuracy. In the etching rate result of FIG. 3, the gas having the characteristic of promoting the etching rate or the gas having the characteristic of suppressing is introduced from only the second etching gas supply means 130, but each gas is supplied to the first etching gas. Even if the gas is supplied from the means 120 and the second etching gas supply means 130 at an arbitrary gas flow rate, the uniformity distribution of the etching rate in the wafer surface can be controlled. Further, even if an inert gas (for example, argon gas) that does not directly contribute to the chemical reaction on the wafer surface is introduced from the second etching gas supply means 130, the uniformity distribution of the etching rate within the wafer surface can be controlled. This is thought to be because the gas flow inside the processing chamber of the etching gas introduced from the first etching gas supply means 120 and the reaction product flow change by supplying the inert gas from the second etching gas supply means 130. It is done.

  In actual etching, even if the uniformity of the etching rate is made uniform in the surface as shown by the curve 301 due to the influence of the plasma distribution, the temperature distribution in the wafer surface and the distribution of reaction products, the etching shape, for example, the line width ( CD) may not be uniform in the wafer plane. Rather, when the etching rate distribution in the wafer surface is a concave distribution or a convex distribution as in the curve 202 and the curve 203, the etching shape in the wafer surface, for example, the line width (CD) may be uniform. Even in such a case, in this embodiment, the etching rate distribution in the wafer surface can be arbitrarily controlled by introducing a desired etching gas at a desired flow rate using the second etching gas supply means 130, and the wafer In-plane etching characteristics, in particular, the etching shape and line width (CD) can be uniformized in a highly precise manner within the wafer surface.

  As described above, by using the first etching gas supply means 120 and the second etching gas supply means 130, the apparatus configured as in the present embodiment arbitrarily controls the etching rate distribution in the wafer surface. It becomes possible. This makes it possible to optimize the etching rate distribution in the wafer surface at each step in the step etching in which the steps of the etching process are sequentially advanced according to a predetermined order when a desired etching shape is obtained. It becomes. Thereby, it is possible to perform highly accurate etching processing, and there is an effect that the apparatus operating rate can be improved and the device yield can be improved.

  In this embodiment, the material to be etched is a polysilicon film, and for example, chlorine gas, tetrafluoromethane gas, or argon gas is used as an etching gas. However, the material to be etched is not only a polysilicon film but also a photoresist film. Anti-reflective organic film, anti-reflective inorganic film, organic material, inorganic material, silicon oxide film, silicon nitride oxide film, silicon nitride film, low-k material, high-k material, amorphous carbon film, Si substrate, metal The same effect can be obtained with materials and the like.

  Examples of gases that promote etching include chlorine gas, hydrogen bromide gas, tetrafluoromethane gas, trifluoromethane, difluoride methane, oxygen gas, nitrogen gas, carbon dioxide, carbon monoxide, hydrogen, and ammonia. , Octafluoropropane, nitrogen trifluoride, sulfur hexafluoride gas, methane gas, silicon tetrafluoride gas, silicon tetrachloride gas, etc. can be used. Examples of gases that suppress etching include chlorine gas and hydrogen bromide. Gas, tetrafluoromethane gas, trifluoride methane, difluoride methane, oxygen gas, nitrogen gas, carbon dioxide, carbon monoxide, hydrogen, ammonia, propane octafluoride, nitrogen trifluoride, sulfur hexafluoride gas, Methane gas, silicon tetrafluoride gas, silicon tetrachloride gas, etc. can be used. Examples of the inert gas include argon gas, helium gas, neon gas, and clear gas. Tongasu, xenon gas, radon gas or the like can be used.

  Also, in such an etching processing apparatus, a laminated film formed by depositing a plurality of materials on a wafer is often etched. The optimum plasma processing conditions differ depending on the material of each film, and the etching performance distribution in the wafer surface during the plasma processing varies greatly. In particular, the in-plane distribution of CD (Critical Dimension) is strongly dependent on the etching gas flow distribution and the reaction product distribution during the plasma processing and is easily affected. For this reason, in the plasma treatment of a laminated film formed by depositing a plurality of materials, step etching in which the steps of the optimum plasma treatment conditions are sequentially advanced depending on the material of each film is effective. In the apparatus configured as in this embodiment, it is possible to arbitrarily control the etching rate distribution in the wafer surface by using the first etching gas supply means 120 and the second etching gas supply means 130. Therefore, the gas flow and the reaction product flow in the processing chamber 104 can be controlled with high accuracy corresponding to each step in the step etching. In other words, there is an effect that it is possible to control so as to obtain a desired CD distribution.

  One embodiment in the case of performing the step etching process on the above laminated film will be described with reference to FIG. FIG. 4 is a sequence diagram for explaining an example of the plasma processing method of the present invention. First, the wafer 112 is mounted on the wafer mounting electrode 111 (step S401). Next, an etching gas is introduced into the processing chamber 104. Using the first or second etching gas supply means, a desired etching gas is introduced into the processing chamber 104 at a desired flow rate so that a gas flow distribution or a reaction product flow distribution in the processing chamber is obtained. (Step S402). Next, plasma is generated in the processing chamber 104, and the wafer 112 is etched (step 404). When etching a laminated film on a wafer, optimum plasma processing conditions differ depending on the material of each film. Therefore, in the case of step etching in which each step is sequentially advanced under the optimum plasma processing conditions for each film (step 405), the gas flow distribution and reaction product flow distribution in the wafer surface during the plasma processing in each step also change greatly. It is necessary to control the gas flow distribution and the reaction product flow distribution with high accuracy corresponding to each step. That is, in order to etch the next film, the etching gas type, flow rate, and mixing ratio of the etching gas introduced from the first or second etching gas supply means 120 and 130 must be adjusted to desired values again. I must. When shifting to the next step etching, first, the plasma is stopped (step 405, it is not always necessary to stop, and the same effect can be obtained without stopping), and the etching gas inside the processing chamber 104 is exhausted. Or maintain (step 406). Next, again using the first or second etching gas supply means 120, 130, a desired etching gas is introduced into the processing chamber 104 at a desired flow rate, and a gas flow distribution or reaction product flow distribution in the processing chamber is introduced. To be. When all the step etching processes are completed (step 404), the application of the DC voltage to the electrostatic chucking electrode is stopped (step 407), the plasma is stopped (step S408), and the etching gas is exhausted (step S409). ). Finally, the wafer 112 is removed from the wafer mounting electrode 111 and carried out of the processing chamber (step S410). In the plasma processing method described above, when the step etching process is performed, the plasma is stopped between the steps (step S406). However, it is not always necessary to stop the plasma between the steps, and the first plasma process is continued while the plasma processing is continued. Alternatively, the type, flow rate, and mixing ratio of the etching gas introduced from the second etching gas supply means 120 and 130 may be changed.

  In the plasma processing method as shown in the present embodiment, the etching rate distribution in the wafer surface can be arbitrarily controlled by using the first etching gas supply means 120 and the second etching gas supply means 130. Therefore, the gas flow and reaction product flow in the processing chamber can be controlled with high precision corresponding to each step in step etching, and plasma processing can be performed so as to obtain a desired etching shape, particularly a desired etching CD distribution. There is an effect.

  In addition, deposits may be formed by performing plasma treatment in the structure of the periphery of the wafer, for example, in the gap between the inner diameter of the susceptor 105 and the outermost periphery of the wafer 112. Such deposits may lead to a decrease in yield in the device manufacturing process. For example, it diffuses into the processing chamber 104 as foreign matter and adheres to the surface of the wafer or device, thereby significantly reducing its performance. However, according to the present embodiment, the etching gas can be caused to flow into the gap between the inner diameter portion of the susceptor 105 and the outermost periphery of the wafer 112 by using the second etching gas supply means 130, thereby suppressing the formation of deposits. Can be made. As a result, the etching process has the effect of improving the stability of the etching performance and further improving the yield.

  In the above embodiments, an etching apparatus using microwave ECR discharge has been described as an example, but other discharges (magnetic field UHF discharge, capacitively coupled discharge, inductively coupled discharge, magnetron discharge, surface wave excited discharge, The same effect can be obtained in a dry etching apparatus using a coupled discharge). In each of the above embodiments, the etching apparatus has been described. However, other plasma processing apparatuses that perform plasma processing, such as a plasma CVD apparatus, an ashing apparatus, and a surface modification apparatus, have similar operational effects.

(Example 2)
A second embodiment of the present embodiment will be described with reference to FIG. The difference between this figure and FIG. 1 will be described below. Except for the following differences, this embodiment is substantially the same as the first embodiment.

  In the plasma processing apparatus of this embodiment, the processing chamber 104, the wafer 112, the wafer mounting electrode 111, the vacuum exhaust port 106, and the vacuum exhaust apparatus (not shown) are arranged coaxially. As a result, the gas flow distribution and reaction product flow distribution inside the processing chamber 104 are axisymmetric. Therefore, the gas flow distribution and reaction product flow distribution inside the processing chamber 104 controlled by the etching gas introduced by the first and second etching gas supply means 120 and 130 according to the present invention are also axisymmetric, Compared with this, it is possible to control the gas flow distribution and reaction product flow distribution with higher accuracy, and the etching rate distribution and etching shape distribution (including CD) in the wafer surface can be controlled with high accuracy and over a wide range. .

DESCRIPTION OF SYMBOLS 101 ... Vacuum container, 102 ... Shower plate, 103 ... Dielectric window, 104 ... Processing chamber, 105 ... Susceptor, 106 ... Vacuum exhaust port, 107 ... Waveguide 109 ... Electromagnetic wave generating power supply, 110 ... Magnetic field generating coil, 111 ... Wafer mounting electrode, 112 ... Wafer, 113 ... Matching circuit, 114 ... High frequency power supply, 120 ... ..First etching gas supply means, 121 ... piping, 122 ... gas valve, 123 ... flow rate regulator, 124 ... gas valve, 125 ... gas cylinder, 130 ... second etching Gas supply means 131... Pipe 132 132 Gas valve 133 Flow rate regulator 134 Gas valve 135 Gas cylinder 136 Gas inlet 201 Gas reservoir, 301, 302, 303 ... etching rate distribution.

Claims (18)

The temperature of the processing chamber to which a vacuum exhaust device is connected and the inside of which can be reduced, a device for supplying gas into the processing chamber, a plasma generating means for generating plasma in the processing chamber, and a wafer as a processing target are controlled. In a plasma processing apparatus comprising means for adsorbing and fixing on an electrode by electrostatic force,
A first etching gas supply means for supplying an etching gas to the processing chamber and a second etching gas supply means provided separately from the first etching gas supply means are provided, and an etching gas flow distribution in the processing chamber is provided. A plasma processing apparatus for controlling a reaction product flow distribution. A processing chamber to which an evacuation apparatus is connected and the inside of which can be depressurized, a device for supplying gas into the processing chamber, a plasma generating means for generating plasma in the processing chamber, and a temperature-controlled electrode of the material to be processed In a plasma processing apparatus comprising means for adsorbing and fixing to an electrostatic force,
One or more types of gas cylinders for supplying one or more types of etching gas, gas pipes and gas valves corresponding to the one or more types of gas cylinders for introducing the one or more types of etching gases, and the one or more types of gas cylinders. One or more types of gas flow controllers corresponding to the one or more types of etching gas for controlling the supply amount of the etching gas and the etching gas of which the one or more types of supply amount are controlled are mixed and introduced into the processing chamber. A first etching gas supply means comprising a gas pipe and a gas valve for performing
Apart from the first etching gas supply means, it corresponds to one or more types of gas cylinders for supplying one or more types of etching gas and the one or more types of gas cylinders for introducing the one or more types of etching gas. Gas pipes and gas valves, one or more gas flow controllers corresponding to the one or more etching gases for controlling the supply of the one or more etching gases, and the one or more supply amounts. A second etching gas supply means comprising a gas pipe and a gas valve for mixing and introducing the controlled etching gas into the processing chamber;
A plasma processing apparatus for controlling an etching gas flow distribution and a reaction product flow distribution in the processing chamber. A processing chamber to which an evacuation apparatus is connected and the inside of which can be depressurized, a device for supplying gas into the processing chamber, a plasma generating means for generating plasma in the processing chamber, and a temperature-controlled electrode of the material to be processed In a plasma processing apparatus comprising means for adsorbing and fixing to an electrostatic force,
The apparatus for supplying a gas into the processing chamber comprises a first etching gas supply means for supplying an etching gas, and a second etching gas supply means provided separately from the first etching gas supply means, The second etching gas supply means is connected to a susceptor provided around the electrode for placing the material to be processed, so that the etching gas can be introduced also from the periphery of the material to be processed,
A plasma processing apparatus for controlling an etching gas flow distribution and a reaction product flow distribution in the processing chamber. In the plasma processing apparatus according to any one of claims 1 to 3,
A plasma processing apparatus, wherein the etching gas introduced from the second etching gas supply means is introduced in a direction substantially parallel to the material to be treated and from the outer periphery of the material to be treated to a substantially central direction. In the plasma processing apparatus according to any one of claims 1 to 3,
The first etching gas supply means is provided on the upper surface of the processing chamber, and the etching gas introduced from the first etching gas supply means is supplied from the upper surface of the processing chamber facing the material to be processed. Plasma processing equipment. In the plasma processing apparatus according to any one of claims 1 to 3,
Etching gas cylinders connected to the etching gas supply means in the first etching gas supply means and the second etching gas supply means, respectively, are common to the first etching gas supply means and the second etching supply means. A plasma processing apparatus characterized by the above. In the plasma processing apparatus according to any one of claims 1 to 3,
The processing chamber, the first etching gas supply means and the second etching gas supply means, the plasma generating means, the electrode for placing the material to be processed, and the vacuum exhaust means are coaxial with respect to the central axis of the processing chamber. A plasma processing apparatus, which is disposed above. In the plasma processing apparatus according to any one of claims 1 to 3,
According to a predetermined order, when sequentially proceeding to each stage of the plasma processing on the material to be processed, the first etching gas supply means and the second etching gas supply means are adjusted at each stage,
An etching gas flow distribution and a reaction product flow distribution in the processing chamber are controlled at each stage. The plasma processing apparatus according to claim 3, wherein
In order to allow the etching gas introduced from the second etching gas supply means to be introduced from the inner diameter portion of the susceptor, one or more substantially slit-shaped openings or hole-shaped openings are provided on the entire circumference of the inner diameter portion. A plasma processing apparatus. The plasma processing apparatus according to claim 3, wherein
The position of the opening provided in the inner diameter portion so that the etching gas introduced from the second etching gas supply means can be introduced from the inner diameter portion of the susceptor is larger than the position of the outermost periphery of the workpiece in the radial direction. A plasma processing apparatus having a large size and a position within 1 mm to 30 mm in the radial direction from the position of the outermost periphery of the material to be processed. The plasma processing apparatus according to claim 3, wherein
A plasma processing apparatus, wherein a gas reservoir is provided inside the susceptor, and a second etching gas supply means is connected to the gas reservoir. The plasma processing apparatus according to claim 3, wherein
The plasma processing apparatus, wherein the susceptor comprises a plurality of members. The plasma processing apparatus according to claim 3, wherein
The plasma processing apparatus, wherein the susceptor has a structure in which a plurality of members are bonded together. A processing chamber to which an evacuation apparatus is connected and whose inside can be depressurized, a device for supplying gas into the processing chamber, a plasma generating means for generating plasma in the processing chamber, and an electrode whose temperature is adjusted for the material to be processed In the plasma processing apparatus consisting of means for adsorbing and fixing on the surface by electrostatic force,
A first etching gas supply means for supplying an etching gas to the processing chamber; and one or more etching gas supply means provided separately from the first etching gas supply means; A plasma processing apparatus for controlling an etching gas flow distribution and a reaction product flow distribution. The inside of the processing chamber is depressurized by a vacuum exhaust device, gas is supplied into the processing chamber, plasma is generated in the processing chamber, and the material to be processed is adsorbed on the temperature-controlled electrode by electrostatic force, and the processing target In a method of plasma processing a material,
First etching gas supply means for supplying an etching gas to the processing chamber, and second etching gas supply means provided separately from the first etching gas supply means, the first etching gas supply means And adjusting each etching gas type, etching gas flow rate, and etching gas flow rate ratio with the second etching gas supply means,
A plasma processing method comprising controlling an etching gas flow distribution and a reaction product flow distribution in the processing chamber. The inside of the processing chamber is depressurized by a vacuum exhaust device, gas is supplied into the processing chamber, plasma is generated in the processing chamber, and the material to be processed is adsorbed on the temperature-controlled electrode by electrostatic force, and the processing target In a method of plasma processing a material,
First etching gas supply means for supplying an etching gas to the processing chamber, and second etching gas supply means provided separately from the first etching gas supply means, the second etching gas supply means Introducing a gas that promotes or suppresses etching of the material to be treated as an etching gas introduced from the above, and an inert gas
A plasma processing method comprising controlling an etching gas flow distribution and a reaction product flow distribution in the processing chamber. The plasma processing method according to claim 16, wherein
According to a predetermined order, when sequentially proceeding with each stage of the plasma treatment of the material to be processed, by adjusting the first etching gas supply means and the second etching gas supply means in each stage, An etching gas flow distribution and a reaction product flow distribution in a processing chamber are controlled at each stage. A processing chamber to which an evacuation apparatus is connected and the inside of which can be depressurized, a device for supplying gas into the processing chamber, a plasma generating means for generating plasma in the processing chamber, and a temperature-controlled electrode of the material to be processed In a plasma processing apparatus comprising means for adsorbing and fixing to an electrostatic force,
A plasma processing apparatus, wherein an etching rate distribution and an etching shape distribution of a material to be processed are controlled by controlling an etching gas flow distribution and a reaction product flow in the processing chamber.

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