JP2012038761A - Substrate processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate processing device for enhancing decomposition efficiency of processing gas and improving processing speed for a substrate.SOLUTION: The substrate processing device comprises: plasma generating means 9 and 11 provided to surround a plasma generating pipe 6, and forming a plasma producing area 12 at least near an inner wall of the plasma generating pipe 6; gas supplying means 16 for supplying processing gas from an upstream side of the plasma generating pipe 6; a processing chamber 4 adjacently arranged on a downstream side of the plasma generating pipe 6, and processing a substrate 3 with the processing gas which has been changed into plasma; a regulator plate 17 provided between the gas supplying means 16 and an upper end of the plasma producing area 12, and regulating the flow of the processing gas to increase the density of the processing gas near the inner wall of the plasma generating pipe; and exhaust means 28 for exhausting the processing gas from the processing pipe.

Description

  The present invention relates to a substrate processing apparatus for manufacturing a semiconductor device by performing plasma processing on a substrate such as a silicon wafer to form a thin film, etching or ashing.

  In the process of manufacturing a semiconductor device, a thin film is formed on a substrate such as a glass substrate or a silicon wafer (hereinafter referred to as a wafer), an etching process for forming a circuit pattern on the wafer, or the resist on the wafer is removed after etching. There are ashing processes to be performed, and examples of processes for processing such processes include a plasma CVD apparatus, a plasma etching apparatus, and a substrate processing apparatus such as an ashing apparatus.

  First, a conventional substrate processing apparatus will be described with reference to FIG.

  The substrate processing apparatus 1 includes a processing container 2 and a processing chamber 4 that is defined in the processing container 2 and performs predetermined processing on the wafer 3. A gas exhaust unit 5 is provided below the processing chamber 4. Is provided.

  An airtight plasma generating tube 6 made of quartz or the like is provided on the processing vessel 2 so as to communicate with the processing chamber 4, and a plasma generating chamber 7 is defined in the plasma generating tube 6. Yes. A gas inlet 8 for introducing a processing gas into the processing chamber 4 is formed above the plasma generating tube 6, and a coil 11 to which a high frequency current can be applied from a high frequency power source 9 around the plasma generating tube 6. By applying a high frequency current to the coil 11, plasma is generated in the plasma generation region 12 near the wall surface of the plasma generating tube 6 near the coil 11.

  The processing gas introduced from the gas inlet 8 is excited, ionized, separated from the processing gas by the induction electromagnetic field generated by the coil 11 to which a high-frequency current is applied, and then converted into plasma, and then the wafer 3 in the processing chamber 4. Reach the surface. The reactive active species that have reached the surface of the wafer 3 contribute to dry etching, dry ashing, and chemical vapor deposition (CVD), and are then exhausted from the gas exhaust unit 5.

  The ratio of reactive active species in the processing gas that reaches the surface of the wafer 3 depends on the ratio at which the processing gas passing through the plasma generation region 12 is excited, that is, the decomposition efficiency. This is an important factor in improving the processing speed such as the film speed.

  However, the plasma generated in the plasma generation chamber 7 is generated not in the entire plasma generation chamber 7 but in the plasma generation region 12. Therefore, when the processing gas is uniformly introduced into the plasma generation tube 6, the processing gas has a maximum flow velocity at the center of the plasma generation tube 6 as shown in FIG. Since it passes through the central portion of the plasma generating tube 6 with low efficiency, the processing gas cannot be decomposed efficiently, and there is a problem that the reactive active species that reaches the surface of the wafer 3 and contributes to the reaction is reduced. there were.

JP 2008-91836 A Japanese Patent Laid-Open No. 11-3799

  In view of such circumstances, the present invention provides a substrate processing apparatus that increases the processing gas supplied to the vicinity of the plasma generation chamber inner wall having a high plasma density, thereby improving the decomposition efficiency of the processing gas and improving the processing speed for the substrate. To do.

  The present invention is provided so as to surround the plasma generation chamber, and generates a plasma region at least in the vicinity of the inner wall of the plasma generation chamber; and a gas supply unit that supplies a processing gas from the upstream side of the plasma generation chamber. A processing chamber that is adjacent to the downstream side of the plasma generation chamber and processes the substrate with a plasma processing gas; and is provided between the gas supply means and the upper end of the plasma region, in the vicinity of the inner wall of the plasma generation chamber The present invention relates to a substrate processing apparatus including a rectifying plate that regulates a flow of a processing gas so that the processing gas density of the gas increases, and an exhaust unit that exhausts the processing gas from the processing chamber.

  According to the present invention, the plasma generating means is provided so as to surround the plasma generating chamber and generates a plasma region at least in the vicinity of the inner wall of the plasma generating chamber, and the gas supply for supplying the processing gas from the upstream side of the plasma generating chamber Means, a processing chamber adjacent to the downstream side of the plasma generation chamber and processing the substrate with the plasma-ized processing gas, and provided between the gas supply means and the upper end of the plasma region, A flow straightening plate that regulates the flow of the processing gas so that the processing gas density near the inner wall becomes dense and an exhaust means for exhausting the processing gas from the processing chamber are provided, so that the density is increased in the vicinity of the inner wall of the plasma generation chamber where the plasma density is high. High processing gas can be supplied, and the decomposition efficiency of the processing gas can be improved and the processing speed of the substrate can be improved. .

It is the schematic which shows the substrate processing apparatus which concerns on this invention. It is a graph which shows the distribution of the relationship between the plasma density and gas flow velocity which concern on the substrate processing apparatus of this invention, and the distance from the plasma generation tube center. It is a graph which shows the relationship between the run-up distance B between the baffle plate which concerns on this invention, and a plasma production area | region, and the ashing rate at the time of performing an ashing process. It is the schematic which shows the conventional substrate processing apparatus. It is a graph which shows the distribution of the relationship between the plasma density and gas flow velocity concerning the conventional substrate processing apparatus, and the distance from the plasma generation tube center.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, referring to FIG. 1, an ashing apparatus will be described as an example of a substrate processing apparatus according to the present invention. In FIG. 1, the same components as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

  On the processing vessel 2 which is a sealed vessel, a plasma generating tube 6 made of quartz, for example, is formed concentrically. A plasma generating coil 11 is provided around the plasma generating tube 6, and the coil 11 is connected to a high frequency power source 9. The coil 11 and the high frequency power source 9 constitute plasma generating means. Yes.

  The coil 11 is surrounded by a shield 13, and the shield 13 is configured so that a high-frequency current flowing through the coil 11 does not affect the surroundings of the apparatus.

  A gas introduction port 8 is formed in the central portion of the top plate of the plasma generation tube 6, and a gas supply tube 14 is connected to the gas introduction port 8, and the gas supply tube 14 is connected to a gas through a flow rate control means 15. Connected to the supply means 16. The gas supply means 16 includes a processing gas (for example, a mixed gas obtained by adding a predetermined ratio of a fluorine-based gas to oxygen gas), a forming gas (for example, a mixed gas obtained by adding a predetermined ratio of hydrogen gas to nitrogen gas), an inert gas, Alternatively, a seasoning gas (for example, oxygen gas) can be supplied into the plasma generation tube 6 through the gas supply tube 14 and the gas inlet 8.

  On the upper end side inside the plasma generation tube 6, for example, a disc-shaped rectifying plate 17 made of quartz is concentric with the plasma generation tube 6 via a support column 18 provided on the top plate of the plasma generation tube 6. The lower end of the current plate 17 and the upper end of the plasma generation region 12 are separated by a run-up distance B. The space inside the plasma generating tube 6 is partitioned by the rectifying plate 17 into an upper gas reservoir 19 of the rectifying plate 17 and a lower plasma generating chamber 7.

  The diameter of the rectifying plate 17 is slightly smaller than the inner diameter of the plasma generating tube 6, and a gap 21 is formed between the inner peripheral surface of the plasma generating tube 6 and the outer peripheral surface of the rectifying plate 17. The gas reservoir 19 and the plasma generation chamber 7 communicate with each other through a gap 21.

  The lower end of the plasma generation tube 6 is opened, and an opening 22 that is concentric with the plasma generation tube 6 and substantially the same diameter as the inner diameter of the plasma generation tube 6 is provided at the center of the top plate of the processing vessel 2. Is formed.

  The inside of the processing container 2 is a processing chamber 4 that is a space for performing predetermined processing on a wafer 3 that is a glass substrate or a substrate such as a silicon wafer, and the processing chamber 4, the plasma generation chamber 7, Are communicated through the opening 22.

  In the processing chamber 4, a substrate holder 23 is installed concentrically with the plasma generation tube 6, and the wafer 3 can be placed concentrically with the substrate holder 23 on the upper surface of the substrate holder 23. . The substrate holding table 23 includes a heating unit (not shown), and the heating unit can heat the mounted wafer 3 to a desired processing temperature.

  An annular space is formed around the substrate holding table 23, and the space serves as a gas exhaust unit 5. The gas exhaust unit 5 includes the outer peripheral surface of the substrate holding table 23 and the processing container 2. An exhaust resistance plate 24 made of, for example, aluminum is provided over the inner peripheral surface, and a required number of vent holes 25 are formed in the exhaust resistance plate 24. The exhaust resistance plate 24 can adjust the exhaust resistance according to the number and inner diameter of the vent holes 25.

  The gas exhaust section 5 is connected to an exhaust pipe 26 via the exhaust resistance plate 24, and the exhaust pipe 26 is connected to an exhaust means 28 such as a vacuum pump via a pressure regulating valve 27. The gas in the processing chamber 4 can be forcibly exhausted through the exhaust resistance plate 24 and the exhaust pipe 26. Further, by adjusting the exhaust flow rate by the pressure adjusting valve 27, the pressure in the processing chamber 4 and the plasma generation chamber 7 can be adjusted to a predetermined pressure value.

  The high-frequency power source 9, the flow rate control means 15, and the exhaust means 28 are connected to a control unit 29. The control unit 29 controls the high-frequency power source 9, and the high-frequency power source 9 supplies a high frequency current to the coil 11. The control unit 29 controls the flow rate control means 15, and the flow rate control means 15 can adjust the flow rate of the gas flowing through the gas supply pipe 14 to a desired flow rate. The controller 29 controls the exhaust means 28, and the exhaust means 28 can adjust the exhaust flow rate to a desired flow rate.

  A substrate loading / unloading port (not shown) is opened at a required location of the processing container 2, and a gate valve (not shown) is installed at the substrate loading / unloading port, and the gate valve closes the substrate loading / unloading port in an airtight manner. The wafer 3 can be opened and opened, and the wafer 3 can be loaded into and unloaded from the processing chamber 4 via the substrate loading / unloading port.

  Further, as an example of the inner diameter of the plasma generating tube 6, in the case of an ashing apparatus that processes an 8-inch wafer 3, 200 mm to 235 mm is preferable. As an example of the mixed gas, oxygen containing 2% freon (fluorine gas) is used.

  Next, ashing processing by the above ashing device will be described.

  A wafer 3 is placed on the substrate holder 23, and the wafer 3 is heated to a predetermined processing temperature by the heating means (not shown). Further, the resist used in the etching process, which is the previous process, is attached to the surface of the wafer 3.

  The control unit 29 controls the flow rate control means 15 to control the gas flow rate, and the process is a mixed gas obtained by adding a fluorine-based gas to the oxygen gas through the gas supply pipe 14 and the gas introduction port 8. Gas is supplied to the gas reservoir 19. The processing gas passes through the gap 21 and descends along the inner peripheral surface of the plasma generation tube 6 and is supplied to the plasma generation chamber 7.

  A high-frequency current is applied to the coil 11 from the high-frequency power source 9, plasma is generated in the processing gas, radical oxygen (radical oxygen) that is a reactive active species is generated, and a plasma generation region 12 is formed. The

  A processing gas containing radical oxygen descends in the plasma generation chamber 7, is supplied to the processing chamber 4, and is exhausted as exhaust gas by the exhaust means 28 through the gas exhaust section 5 and the exhaust pipe 26. The exhaust means 28 exhausts the exhaust gas at a predetermined flow rate, and the exhaust resistance is adjusted by the exhaust resistance plate 24, so that the pressure in the plasma generation chamber 7 and the processing chamber 4 becomes a predetermined processing pressure. Adjusted to In addition, the arrow in a figure has shown the flow of said gas.

  The radical oxygen in the processing gas comes into contact with the wafer 3, and the resist on the surface of the wafer 3 is oxidized by the radical oxygen, and the resist becomes carbon dioxide, water, etc., removed from the surface of the wafer 3, and exhausted from the processing chamber 4 together with the exhaust gas. Is done.

  In addition, as an example of the processing chamber temperature, gas flow rate, and processing chamber pressure in the ashing process described above, the processing chamber temperature is 250 ° C., and the gas flow rate is 1 L / min or more, preferably 3 L / min. 15 L / min and the processing chamber pressure are 133 Pa to 665 Pa.

  FIG. 2 is a distribution showing the relationship between the plasma density and gas flow velocity (gas density) in the A section (see FIG. 1) and the distance from the center of the plasma generating tube 6 when the ashing process is performed. FIG.

  In the figure, two gas flow rates are shown: a run-up distance B, that is, a distribution when the distance from the lower end of the rectifying plate 17 to the upper end of the plasma generation region 12 is 5 mm, and a distribution when the run-up distance B is 30 mm. Distribution is shown.

  The plasma density decreases as it approaches the center of the plasma generation chamber 7, increases as it approaches the vicinity of the inner wall of the plasma generation chamber 7, and increases as it approaches the coil 11 serving as plasma generation means. The In addition, the same tendency as the plasma density is observed with respect to the gas flow velocity, but the case where the run distance B is 5 mm is closer to the inner wall of the plasma generation chamber 7 than the case where the run distance B is 30 mm. You can see that the flow rate is high.

  From the above, it can be seen that the gas flow velocity can be increased in the vicinity of the inner wall of the plasma generation chamber 7 and the gas flow velocity distribution shape can be made closer to the plasma density distribution shape when the running distance B is smaller.

  FIG. 3 is a graph showing the relationship between the approaching distance B and the ashing rate in the ashing process. It can be seen that the ashing rate is improved as the approaching distance B is decreased. Further, from the figure, when the run-up distance B is 30 mm or less, the improvement of the ashing rate is remarkable, and therefore the run-up distance B is preferably B ≦ 30 mm.

  Although not shown in the figure, for example, when the running distance B is set to 0 mm, the rectifying plate 17 inhibits the plasma generation in the portion A and the plasma generation efficiency is lowered. It is desirable that the size does not hinder the generation of plasma.

  From FIG. 2 and FIG. 3, it can be predicted that the distribution shape of the gas flow velocity approaches the distribution shape of the plasma density as the approach distance B is reduced. Therefore, the amount of the processing gas passing through the plasma generation region 12 can be increased by reducing the running distance B, the decomposition efficiency of the processing gas can be improved, and the processing speed for the wafer 3 can be improved. .

(Appendix)
The present invention includes the following embodiments.

  (Supplementary Note 1) Plasma generating means provided so as to surround the plasma generation chamber and generating a plasma region at least near the inner wall of the plasma generation chamber; and gas supply means for supplying a processing gas from the upstream side of the plasma generation chamber; A processing chamber that is adjacent to the downstream side of the plasma generation chamber and processes the substrate with a plasma processing gas; and is provided between the gas supply means and the upper end of the plasma region, in the vicinity of the inner wall of the plasma generation chamber A substrate processing apparatus comprising: a rectifying plate that regulates a flow of the processing gas so that the processing gas density of the gas increases; and an exhaust unit that exhausts the processing gas from the processing chamber.

  (Appendix 2) The plasma generating means generates plasma having a density higher than that of the center of the plasma generation chamber near the inner wall of the plasma generation chamber, and the rectifying plate is closer to the wall of the plasma generation chamber than the center of the plasma generation chamber. The substrate processing apparatus according to appendix 1, which generates a high gas flow rate.

DESCRIPTION OF SYMBOLS 1 Substrate processing apparatus 3 Wafer 4 Processing chamber 6 Plasma generating tube 7 Plasma generating chamber 9 High frequency power supply 11 Coil 12 Plasma generating area 17 Current plate 28 Exhaust means

Claims (1)

  Plasma generating means provided to surround the plasma generating chamber and generating a plasma region at least in the vicinity of the inner wall of the plasma generating chamber, gas supply means for supplying a processing gas from the upstream side of the plasma generating chamber, and the plasma generating A processing chamber adjacent to the downstream side of the chamber and processing the substrate with the plasmaized processing gas; and a processing gas density near the inner wall of the plasma generation chamber provided between the gas supply means and the upper end of the plasma region A substrate processing apparatus, comprising: a rectifying plate that adjusts a flow of a processing gas so that the concentration of the processing gas is increased; and an exhaust unit that exhausts the processing gas from the processing chamber.

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