JP2013219256A - Dry etching device and dry etching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dry etching device and a dry etching method, capable of controlling reaction with high accuracy in a dry etching device under atmospheric pressure using a ClF3 gas.SOLUTION: A dry etching device comprises: a chamber having a gas introduction port; a stage which is disposed in the chamber and on which a substrate is mounted; a gas supply line connected to the gas introduction port in the chamber and introducing a gas into the chamber; and an exhaust device connected to the chamber and discharges a gas in the chamber. The gas supply line is connected to a gas supply unit, and a bypass line is connected to the gas supply line. The exhaust device is connected to the other end of the bypass line.

Description

  The present invention relates to a technique for treating the surface of a silicon substrate, for example, and particularly to a technique for forming a texture on the surface of a silicon substrate for a solar cell.

  In general, when sunlight reaches a silicon substrate serving as a cell in a solar battery, the light is separated into light entering the silicon substrate and light reflected from the surface of the silicon substrate. Since only the light that enters the silicon substrate among these lights contributes to the photovoltaic effect, a texture in which a large number of concave and convex portions are continuous on the surface of the silicon substrate in order to reduce the reflectance on the surface of the silicon substrate. The shape is formed.

  Conventionally, wet etching methods (see, for example, Patent Documents 1 and 2) have been the mainstream for texturing the surface of such a silicon substrate. The shift to dry etching, such as a method using reactive ion etching, is beginning to proceed.

  FIG. 4 is a diagram showing a general reactive ion etching apparatus configuration. A general reactive ion etching method will be described with reference to FIG.

  A silicon substrate 3 is placed on the stage 2 of the chamber 1 which has been previously held in vacuum. Process gas is introduced into the shower plate 14 from the gas supply line 6 via the mass flow controller 5 from the cylinder 4. The process gas is uniformly dispersed in the buffer layer in the shower plate 14 and supplied into the chamber 1 in the form of a shower. The supply and termination of the process gas are appropriately controlled by the mass flow controller 5 and the valve 10 ahead. The chamber 1 is evacuated by the vacuum pump 7 and adjusted to a desired pressure by the pressure adjusting valve 8, and then power is applied to the stage from the high frequency power supply 15.

  As a result, plasma is generated in the chamber, whereby the activated ions and radicals react with the silicon substrate 3, and etching proceeds to form a texture.

  On the other hand, a dry etching method under atmospheric pressure using chlorine trifluoride gas (ClF3) (for example, refer to Patent Document 3) is also attracting attention as a texture forming method by dry etching without using reactive ion etching. .

  FIG. 5 is a diagram showing a dry etching method under atmospheric pressure using chlorine trifluoride gas (ClF 3) described in Patent Document 3.

  A stage 2 is provided in a chamber 1 under atmospheric pressure that has been previously replaced with N 2 gas, a silicon substrate 3 is placed, and a predetermined flow rate is passed from a cylinder 4 through a mass flow controller 5 through a gas supply line 6. The ClF 3 gas is introduced and exhausted by the vacuum pump 7. As a result, by exposing the silicon substrate 3 to the ClF 3 gas, it is possible to react with silicon only by a chemical reaction in the gas layer and form etch pits, thereby forming a texture.

  Compared to reactive ion etching, this process performs etching without generating plasma, so plasma damage to the silicon substrate does not occur theoretically, and attention is paid to the development of solar cells with high power generation efficiency. Has been.

JP 2006-344765 A JP 2007-194485 A Japanese Patent Laid-Open No. 10-178194

  However, the dry etching method performed by a chemical reaction in the gas layer under the atmospheric pressure using ClF 3 gas as in Patent Document 3 has a problem peculiar to the gas layer reaction. This will be described with reference to FIGS.

  FIG. 6 is a flowchart showing a dry etching method under atmospheric pressure using chlorine trifluoride gas (ClF 3) described in Patent Document 3.

  In this case, the flow is substrate placement (process P1), N2 gas replacement (process P2), process gas introduction (process P3), process gas end (process P4), and exhaust (process P5). Here, the silicon substrate 3 shown in FIG. 5 passes through the process gas introduction (process P3), the process gas ends (process P4), and the process gas in the chamber 1 is sufficiently exhausted by the exhaust (process P5). During this time, a chemical reaction proceeds and etching occurs.

  FIG. 7 is a flowchart showing a general reactive ion etching method.

  In this case, substrate placement (process P1)-process gas introduction (process P2)-pressure adjustment (process P3)-discharge start (process P4)-discharge end (process P5)-process gas end (process P6)-exhaust The flow is (Process P7). In the case of reactive ion etching by plasma, ions and radicals excited by plasma discharge react with silicon, so that the reaction itself is performed in the range from the start of discharge (process P4) to the end of discharge (process P5). Since the discharge can be started and ended instantaneously, it can be performed without being influenced by the time for introducing the process gas (process P2) and exhausting (process P7).

  That is, when etching is performed only by a chemical reaction by the gas layer, the entire time during which the silicon substrate is exposed to the process gas contributes to the etching.

  Here, a texture forming method using ClF 3 gas and O 2 gas will be described. The authors formed not only ClF3 gas but also O2 gas in a chemical reaction in the air layer under atmospheric pressure to form better etch pits and texture the silicon substrate surface. We are studying how to achieve this.

The supplied ClF 3, O 2 gas and Si react in the gas layer,
3Si + 4ClF3 → 3SiF4 ↑ + 2Cl2 ↑ (1)
Si + O2 → SiO2 (2)
Reaction occurs. According to the formula (1), ClF3 reacts with Si to become gaseous SiF4 and etching progresses. At the same time, SiO2 shown in the formula (2) is generated on the etched surface, which becomes a self-mask and has a plane orientation of single crystal silicon. It has been found that along etching is performed.

  In particular, as shown in Patent Document 3, when a silicon substrate having a surface orientation (1.1.1) on the surface is etched, a texture having triangular pyramid-shaped etch pits is obtained, and the surface orientation (1.0.0) When a silicon substrate having a surface is etched, a texture having a rectangular etch pit is obtained.

  However, even if a good texture is formed, if the process gas continues to be exposed to the silicon substrate surface, the formed texture further undergoes a chemical reaction, and the texture shape is destroyed. In particular, after the formation of a good texture, it is necessary to stop the gas supply to the chamber and exhaust the residual gas in the chamber instantaneously.

  The present invention solves the above-described conventional problems, and provides a dry etching apparatus and a dry etching method capable of controlling the reaction with high precision in a dry etching apparatus using ClF 3 gas under atmospheric pressure. The purpose is to provide.

  In order to achieve the above object, a dry etching apparatus of the present invention has the following characteristics.

[1] a chamber having a gas inlet;
A stage placed in the chamber and on which the substrate is placed;
A gas supply line connected to the gas inlet of the chamber and introducing gas into the chamber;
In a dry etching apparatus comprising: an exhaust device that is connected to the chamber and exhausts gas in the chamber.
The gas supply line is connected to a gas supply unit, a bypass line is connected to the gas supply line, and an exhaust device is connected to the other end of the bypass line;
A dry etching apparatus characterized by the above.

  [2] In the above [1], a valve is disposed between the gas supply section and the gas inlet in the gas supply line, and the gas supply line between the valve and the gas inlet A dry etching apparatus in which a bypass line is connected.

  [3] The dry etching apparatus according to [1] or [2], wherein the gas supply unit includes a plurality of gas supply units.

  [4] A dry etching apparatus according to [1] to [3], wherein a valve is disposed in the bypass line.

[5] The dry etching apparatus according to [1] to [4], wherein the exhaust apparatus for exhausting the gas in the chamber and the exhaust apparatus connected to the other end of the bypass line are the same.
The dry etching method of the present invention has the following characteristics.

[6] In a dry etching method for etching a substrate placed in a chamber,
A first step of supplying gas into the chamber via a gas supply line;
A second step of stopping the supply of the gas after etching the substrate;
A third step of exhausting the gas in the chamber and exhausting the gas through a bypass line connected to the gas supply line.

  [7] The dry etching method according to [6], wherein the first step is performed with a valve disposed in the bypass line being closed, and the third step is performed with the valve being opened.

  [8] The dry etching method according to [6] or [7], wherein the method includes a plurality of etching steps having different gas ratios, and each step includes the first to third steps.

  [9] The dry etching method according to [6] to [8], wherein the etching of the substrate is performed in a range of atmospheric pressure to 30 kPa.

  [10] The dry etching method according to [6] to [9], wherein the gas supplied into the chamber is a fluorine-based gas, an O 2 gas, and an N 2 gas.

  [11] The dry etching method according to [10], wherein the fluorine-based gas is ClF3 gas.

  By using the dry etching apparatus under atmospheric pressure using the ClF3 gas of the present invention, when performing only a chemical reaction by a gas layer, the gas can be exhausted instantaneously, and the reaction is controlled with high accuracy. be able to.

  Also, according to this configuration, not only the chamber but also the gas supply line is exhausted. Therefore, when incorporating a plurality of steps for changing the gas flow rate by combining a plurality of gases, the gas ratio and flow rate of the previous step are incorporated. The processing conditions can be changed without being influenced by the above.

Device diagram showing an embodiment of the present invention Flow chart of dry etching showing Embodiment 1 of the present invention Flow chart of dry etching showing Embodiment 2 of the present invention General reactive ion etching equipment diagram Diagram of dry etching apparatus using ClF3 gas described in Patent Document 3 Flow chart of dry etching using ClF3 gas described in Patent Document 3 General reactive ion etching flow diagram The figure which shows the reaction temperature profile in Embodiment 1 of this invention The figure which shows the comparative reaction temperature profile with respect to Embodiment 1 when not using this invention The figure which shows the etching pit shape when etching the silicon substrate which has the surface orientation (1.1.1) surface in Embodiment 1 of this invention on the surface The figure which shows the comparison shape with respect to Embodiment 1 when not using this invention The figure which shows the reaction temperature profile in Embodiment 2 of this invention The figure which shows the comparative reaction temperature profile with respect to Embodiment 2 when not using this invention The figure which shows the etch pit shape when etching the silicon substrate which has a surface orientation (1.1.1) surface in Embodiment 2 of this invention on the surface The figure which shows the comparison shape with respect to Embodiment 2 when not using this invention

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a diagram showing an etching apparatus according to an embodiment of the present invention.

  As an example, it is assumed that there are three process gas supply lines. A stage 2 is provided on the chamber 1 and a silicon substrate 3 is placed thereon. The inside of the chamber 1 is maintained at atmospheric pressure by a pressure regulating valve 8 and a vacuum pump 7.

  The cylinder 41 is an N2 cylinder and is connected to a gas supply line 61 in which a mass flow controller 51 and a valve 101 are installed. The cylinder 42 is a cylinder of ClF 3 and is connected to a gas supply line 62 in which a mass flow controller 52 and a valve 102 are installed. Further, the cylinder 43 is an O 2 cylinder and is connected to a gas supply line 63 in which the mass flow controller 53 and the valve 103 are installed. These gas supply lines 61 to 63 are finally joined and supplied from the gas inlet A into the chamber as a mixed gas.

  Here, the position of the valves 101 to 103 is C. In the embodiment of the present invention, the valves 101 to 103 are installed immediately after the mass flow controllers 51 to 53. However, the valves 101 to 103 can be opened and closed by opening and closing the mass flow controllers 51 to 53. Therefore, the installation of the valves 101 to 103 may be eliminated. However, a general mass flow controller may cause a very small flow rate to leak inside even when fully closed, and it is usually common to provide a valve immediately after the mass flow controller.

  The gas supplied into the chamber 1 from the gas inlet A first fills the buffer layer of the shower plate 14 and is exposed to the surface of the silicon substrate 3 through the pores of the shower plate 14. On the surface of the silicon substrate 3, a chemical reaction occurs in the air layer, and a texture (uneven shape) is generated. The gas generated by the chemical reaction with the supplied gas is exhausted from the vacuum pump 7.

  The bypass line 9 is branched at a branch point B of the bypass line on the gas supply line, and is connected to a vacuum pump 13 as an exhaust facility via a valve 11. As appropriate, the gas supply lines 61 to 63 and the exhaust of the chamber 1 can be performed through the bypass line 9.

  The N2 gas supplied from the cylinder 41 is a gas for adjusting the concentration of ClF3 and O2 gas and for replacing the gas in the chamber 1, and may be any inert gas that does not contribute to a chemical reaction, such as a rare gas. But you can. Further, the branch point B of the bypass line on the gas supply line may be at any position between the gas inlet A and the position C of the valves 101 to 103.

  FIG. 2 is an etching flowchart showing the first embodiment of the dry etching method using the apparatus of FIG. From this, it is the dry etching method of this invention using FIG. 2, Comprising: By providing a bypass line in a gas supply line, and performing exhaust by a bypass line and chamber exhaust, reaction is carried out by shortening exhaust time. A method of controlling with high accuracy will be described.

  (Start): At the start, the mass flow controllers 51 to 53, the valves 101 to 103, and the valve 11 are closed, and the pressure inside the chamber 1 is maintained at the atmospheric pressure by the pressure adjusting valve 8.

  (Process P1)... The silicon substrate 3 is placed on the stage 2.

  (Process P2)... From here, the mass flow controller 51 and the valve 101 set to a predetermined flow rate of 15 slm are opened, and in order to replace the inside of the chamber 1 with an inert gas, the gas is passed from the cylinder 41 through the gas supply line 61 and N2. Gas is supplied from the gas inlet A. The inside of the chamber 1 is regulated and stabilized at atmospheric pressure using a pressure regulating valve 8 and a vacuum pump 7.

  (Process P3) Next, the mass flow controller 52 set to the predetermined flow rate 1 slm and the valve 102 are opened, and the ClF 3 is supplied through the gas supply line 62, and at the same time, the mass flow controller 53 set to the predetermined flow rate 4 slm. The valve 103 is opened, and O 2 is supplied through the gas supply line 63 and introduced from the gas inlet A as a mixed gas of ClF 3, O 2, and N 2.

  After the mixed gas fills the buffer layer of the shower plate 14, the mixed gas is uniformly exposed to the surface of the silicon substrate 3 through the pores of the shower plate 14. On the surface of the silicon substrate 3, the reactions of the above formulas (1) and (2) proceed, and a texture is formed.

  (Step P4) ... After the formation of the texture, the supply of the process gas is terminated. In order to end the supply of N2, ClF3, and O2 gas, the mass flow controllers 51 to 53 and the valves 101 to 103 are closed.

  (Step P5) ... Simultaneously with (Step P4), exhaust of the process gas is required immediately. As the time for which the residual process gas is exposed to the surface of the silicon substrate 3 becomes longer, excessive etching proceeds and the texture shape is destroyed.

  For this reason, the pressure regulating valve 8 is fully opened, the exhaust from the chamber side using the vacuum pump 7, and the valve 11 is opened to exhaust from the bypass line 9 side using the vacuum pump 13. Thus, simultaneously with the exhaust in the chamber 1, the residual gas in the buffer layer of the shower plate 14 and in the vicinity of the surface of the silicon substrate 3 is also bypassed from the position C of the valves 101 to 103 through the gas inlet A. From 9 side, it can exhaust instantly.

  FIG. 8 is a reaction temperature profile in Embodiment 1 of the present invention. The above formulas (1) and (2) are exothermic reactions. For this reason, the progress of the chemical reaction can be estimated by measuring the temperature of the silicon substrate. That is, the reaction is accelerated as the temperature is higher, and the reaction is lower as the temperature is lower.

  In FIG. 8, it can be seen that the temperature rises from room temperature and the reaction proceeds simultaneously with the start of the process P3. After texture formation by etching for a predetermined time, the process P5 was performed simultaneously with the process P4, and exhaust by the bypass line and chamber exhaust were performed. It can be seen from the graph that the chemical reaction time with the residual gas is about 25 seconds.

  On the other hand, FIG. 9 is a comparative reaction temperature profile when the first embodiment of the present invention is not used. After etching for a predetermined time and forming etch pits, P5 is performed simultaneously with the process P4. In the process P5, the valve 11 is kept closed, the pressure regulating valve 8 is fully opened, and only the chamber exhaust is used. is there. Similarly, it can be seen from the graph that the chemical reaction time with the residual gas is about 125 seconds.

  As described above, when the first embodiment of the present invention is used, the etching time by the residual gas can be greatly shortened.

  FIG. 10 shows a texture shape when a silicon substrate having a surface orientation (1.1.1) plane is etched using the first embodiment of the present invention shown in FIG.

  FIG. 11 shows a texture shape when a silicon substrate having a surface orientation (1.1.1) plane is etched when the first embodiment of the present invention shown in FIG. 9 is not used.

  When the first embodiment of the present invention is used, a triangular pyramid-shaped etch pit is formed. However, when the first embodiment is not used, the shape is a porous surface, and the texture It can be seen that the shape is not formed.

  FIG. 3 is an etching flowchart showing a second embodiment of the dry etching method using the apparatus of FIG. From this, the method of controlling the reaction with high accuracy by shortening the exhaust time by providing a bypass line in the gas supply line of the present invention and performing exhaust by the bypass line and exhausting the chamber by using FIG. A case where a plurality of etching steps having different gas ratios is provided will be described.

  As an example, an etching method having a first step and a second step, etching in only ClF3 in the first step, and etching in a mixed gas of ClF3 and O2 in the second step will be described. . It has been found by the authors that this etching method is effective as a method for controlling the size of the texture shape.

(First step)
(Start): At the start, the mass flow controllers 51 to 53, the valves 101 to 103, and the valve 11 are closed, and the pressure inside the chamber 1 is maintained at the atmospheric pressure by the pressure adjusting valve 8.

  (Process P1)... The silicon substrate 3 is placed on the stage 2.

  (Process P2)... From here, the mass flow controller 51 and the valve 101 set to a predetermined flow rate of 15 slm are opened, and in order to replace the inside of the chamber 1 with an inert gas, the gas is passed from the cylinder 41 through the gas supply line 61 and N2. Gas is supplied from the gas inlet A. The inside of the chamber 1 is regulated and stabilized at atmospheric pressure using a pressure regulating valve 8 and a vacuum pump 7.

  (Process P3)... Next, the mass flow controller 52 and the valve 102 set to the predetermined flow rate 1 slm are opened, and ClF 3 is introduced from the gas inlet A through the gas supply line 62.

  The mixed gas of ClF 3 and N 2 fills the buffer layer of the shower plate 14 and is then exposed to the surface of the silicon substrate 3 uniformly from the pores of the shower plate 14. On the surface of the silicon substrate 3, the reaction of only the above formula (1) proceeds.

  (Step P4) ... After the etching for a predetermined time, the supply of the process gas is terminated. In order to end the supply of N2 and ClF3, the mass flow controllers 51 to 52 and the valves 101 to 102 are closed.

  (Step P5) ... Simultaneously with (Step P4), exhaust of the process gas is required immediately. This is because the longer the time during which the residual process gas is exposed to the surface of the silicon substrate 3, the more etching is performed.

  In addition, since the gas ratio in the second step is different from that in the first step, the first step passes from the position C of the valves 101 to 103 through the gas inlet A and into the buffer layer of the shower plate 14. The mixed gas used in (1) remains, and etching is performed with the residual gas at the initial stage of the second step, which hinders the control of etching.

  For this reason, the pressure regulating valve 8 is fully opened, the exhaust from the chamber side using the vacuum pump 7, and the valve 11 is opened to exhaust from the bypass line 9 side using the vacuum pump 13. Thus, simultaneously with the exhaust in the chamber 1, the residual gas in the buffer layer of the shower plate 14 and in the vicinity of the surface of the silicon substrate 3 is also bypassed from the position C of the valves 101 to 103 through the gas inlet A. From 9 side, it can exhaust instantly.

(Second step)
(Process P6)... From here, the valve 11 is closed and the second step is started. The mass flow controller 51 and valve 101 set to a predetermined flow rate of 15 slm are opened, and N 2 gas is supplied from the gas inlet 41 through the gas supply line 61 from the cylinder 41 to replace the inside of the chamber 1 with the inert gas. . The inside of the chamber 1 is regulated and stabilized at atmospheric pressure using a pressure regulating valve 8 and a vacuum pump 7.

  (Process P7)... Next, the mass flow controller 52 and valve 102 set to the predetermined flow rate 1 slm are opened, and ClF3 is supplied through the gas supply line 62, and the mass flow controller 53 and valve 103 set to the predetermined flow rate 4 slm. Is opened, O2 is supplied through the gas supply line 63, and is introduced from the gas inlet A as a mixed gas of ClF3, O2, and N2.

  After the mixed gas fills the buffer layer of the shower plate 14, the mixed gas is uniformly exposed to the surface of the silicon substrate 3 through the pores of the shower plate 14. On the surface of the silicon substrate 3, the reactions of the above formulas (1) and (2) proceed, and a texture is formed.

  (Step P8) ... After the formation of the texture, the supply of the process gas is terminated. In order to end the supply of N2, ClF3, and O2 gas, the mass flow controllers 51 to 53 and the valves 101 to 103 are closed.

  (Step P9) ... Simultaneously with (Step P8), exhaust of the process gas is required immediately. This is because the longer the time during which the residual process gas is exposed to the surface of the silicon substrate 3, the more excessive etching proceeds and the texture shape is destroyed.

  For this reason, the pressure regulating valve 8 is fully opened, the exhaust from the chamber side using the vacuum pump 7, and the valve 11 is opened to exhaust from the bypass line 9 side using the vacuum pump 13. Thus, simultaneously with the exhaust in the chamber 1, the residual gas in the buffer layer of the shower plate 14 and in the vicinity of the surface of the silicon substrate 3 is also bypassed from the position C of the valves 101 to 103 through the gas inlet A. From 9 side, it can exhaust instantly.

  FIG. 12 is a reaction temperature profile in Embodiment 2 of the present invention. It can be seen from the graph that the chemical reaction time due to the residual gas in the first step is about 12 seconds, and the chemical reaction time due to the residual gas in the second step is about 13 seconds.

  On the other hand, FIG. 13 is a comparative reaction temperature profile when the second embodiment of the present invention is not used. It can be seen from the graph that the chemical reaction time due to the residual gas in the first step is about 57 seconds, and the chemical reaction time due to the residual gas in the second step is about 77 seconds.

  As described above, when the second embodiment of the present invention is used, the etching time by the residual gas can be greatly shortened.

  FIG. 14 shows a texture shape when a silicon substrate having a surface orientation (1.1.1) plane is etched using the second embodiment of the present invention shown in FIG.

  FIG. 15 shows a texture shape when a silicon substrate having a surface orientation (1.1.1) plane is etched when the second embodiment of the present invention shown in FIG. 13 is not used.

  The shape in the case of using the second embodiment of the present invention forms a triangular pyramid texture shape, but in the case of not using the second embodiment, it has a porous surface shape and has a texture. It can be seen that the shape is not formed.

  In addition, in the method which shows the above-mentioned embodiment, in order to prevent the gas leak from the chamber 1, you may implement holding | maintenance under atmospheric pressure under the weak decompression to about 30 kPa from atmospheric pressure.

  As described above, in an atmospheric pressure dry etching apparatus using ClF 3 gas, a bypass line is provided in the gas supply line, and the exhaust time is shortened by exhausting from the bypass line. The chemical reaction can be suppressed and high-precision etching can be expected.

  By forming a texture of a highly accurate etch pit on a silicon substrate used in a solar cell by the dry etching method of the present invention, a solar cell with high light confinement effect and high power generation efficiency can be provided. In addition, plasma damage as seen in dry etching by reactive ion etching using conventional plasma does not occur theoretically, and an efficient solar cell can be provided.

DESCRIPTION OF SYMBOLS 1 Chamber 2 Stage 3 Silicon substrate 4,41,42,43 Cylinder 5,51,52,53 Mass flow controller 6,61,62,63 Gas supply line 7 Vacuum pump 8 Pressure regulating valve 9 Bypass line 10,101,102, 103 Valve 11 Valve 13 Vacuum pump 14 Shower plate A Gas inlet B Branch point of bypass line C Position of valves 101-103

Claims (11)

A chamber having a gas inlet;
A stage placed in the chamber and on which the substrate is placed;
A gas supply line connected to the gas inlet of the chamber and introducing gas into the chamber;
In a dry etching apparatus comprising: an exhaust device that is connected to the chamber and exhausts gas in the chamber.
The dry etching apparatus, wherein the gas supply line is connected to a gas supply unit, a bypass line is connected to the gas supply line, and an exhaust device is connected to the other end of the bypass line. A valve is disposed between the gas supply part and the gas inlet in the gas supply line,
The dry etching apparatus according to claim 1, wherein a bypass line is connected to the gas supply line between the valve and the gas inlet.   The dry etching apparatus according to claim 1, wherein the gas supply unit includes a plurality of gas supply units.   The dry etching apparatus according to claim 1, wherein a valve is disposed in the bypass line.   The dry etching apparatus according to any one of claims 1 to 4, wherein an exhaust apparatus that exhausts the gas in the chamber and an exhaust apparatus connected to the other end of the bypass line are the same. In a dry etching method for etching a substrate placed in a chamber,
A first step of supplying gas into the chamber via a gas supply line;
A second step of stopping the supply of the gas after etching the substrate;
A third step of exhausting the gas in the chamber and exhausting the gas through a bypass line connected to the gas supply line. The first step is performed with a valve disposed in the bypass line closed,
The dry etching method according to claim 6, wherein the third step is performed with the valve open.   8. The dry etching method according to claim 6, further comprising a plurality of etching steps having different gas ratios, wherein each step includes the first to third steps.   The dry etching method according to any one of claims 6 to 8, wherein the etching of the substrate is performed in a range of atmospheric pressure to 30 kPa.   The dry etching method according to claim 6, wherein the gas supplied into the chamber is a fluorine-based gas, an O 2 gas, and an N 2 gas.   The dry etching method according to claim 10, wherein the fluorine-based gas is ClF 3 gas.

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