JP2004312029A - Etching system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the operating cost of an etching system and an investment to an industrial detoxifying facility by separating a large quantity of unreacted gas presently discharged into the atmosphere and reusing or recovering the separated gas by circulation, and in addition, reducing the energy consumption of a pump used for discharging etching gas by reducing a load imposed on the pump. <P>SOLUTION: Gases, reaction products, or unreacted gases discharged from a processing chamber 11 are separated into etching gas and reaction products by introducing them to a separating means 50 such as a filter or a cyclone, and the reaction products are further separated into solid bodies of materials to be etched and into original etching gas by dissociating the reaction products. The separated etching gas is circulated to the processing chamber 11 via a circulating and storing means 60 and a flow passage control section 71, and reused. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an etching method and an apparatus used for manufacturing a semiconductor device.

  Many gases used for etching are active and harmful, such as CCl4, Cl2, CF4 (-O2), and the gas discharged from the etching equipment is collected by various abatement equipment and disposed of by a specialized contractor. Have been. Further, in order to automatically remove harmful gas from exhaust gas of a semiconductor manufacturing apparatus, an exhaust gas processing apparatus such as a purification apparatus as disclosed in Patent Document 1 has been proposed. On the other hand, as described in Patent Literature 2 and Patent Literature 3, it is known that useful components are separated and recovered from exhaust gas from a coating film forming apparatus or vacuum degassing equipment and reused.

  However, there is no example in the field of plasma etching that discloses reusing exhaust gas.

JP-A-2-9438

JP-A-60-137465 JP-A-61-9513

  By the way, when etching a wafer, the amount of the etching gas that is actually effectively used is estimated to be about 20% at most, and the etching by the current etching apparatus discharges a large amount of harmful industrial waste. And a great deal of investment is being spent on these abatement equipment.

  Further, a vacuum pump for discharging the gas into the atmosphere in the etching apparatus is a large power consumption source.

  An object of the present invention is to reduce the operating cost of the apparatus and reduce the investment in abatement equipment by separating, circulating, and reusing or recovering a large amount of unreacted gas that is currently released to the atmosphere. Is to do.

  Another object of the present invention is to reduce the load on the pump for discharging the etching gas and save energy.

  As is clear from the principle of the etching, the etching gas is not consumed by the etching, but is merely combined with the material to be etched to change the shape. Here, consumption refers to a state in which a part of gas components is deposited on a substrate, as in CVD. According to the present invention, a gas discharged in combination with a material to be etched, a reaction product or a gas discharged unreacted is separated into an etching gas and a solid, and the etching gas is circulated for use.

  That is, the unused etching gas is separated from the reaction products generated by the etching by the primary separation means such as a filter and a cyclone. Further, the reaction product, that is, the solid matter which is discharged in combination with the material to be etched is separated by the secondary separation means using heat or plasma to separate the solid matter of the material to be etched from the original etching gas. The reaction product can be separated or re-separated by giving energy equal to or higher than the binding energy. The secondary separated etching gas is circulated and used like the unreacted gas.

  The etching gas once introduced into the processing chamber is partially used for etching and is discharged out of the processing chamber, but since the pump for discharging has a compression ratio, the pump on the discharge side must be located on the processing chamber side. The higher the pressure. Therefore, it is very easy to introduce this etching gas into the processing chamber again. In recent years, a completely oil-free pump has been completed, and the etching gas is not contaminated by passing through the pump.

  If the reaction product generated by the etching can be recovered at a distance of 100%, the etching gas will be repeatedly supplied only at a fixed amount in the initial stage without being supplied permanently. Also, since there is no need to discharge gas into the atmosphere, the pump can circulate gas with a light load. However, in an actual operation, the reaction product cannot be separated by 100%, and there is a loss accompanying the replacement of the processing object. Therefore, it is necessary to replenish the etching gas only for the loss. As for the pump, it is necessary to discharge only the loss to the outside of the apparatus. However, compared to the current power to discharge all of them to the atmosphere, they are very small.

According to the present invention, the following effects can be obtained.
(1) Expensive etching gas can be used effectively, and running costs can be reduced.

(2) Since the amount of gas discharged from the apparatus is small, the burden on the abatement equipment and exhaust gas equipment is reduced, so that investment in these auxiliary equipment can be reduced.
(3) Since most of the gas is used in the closed system, there is no influence on the environment.
(4) Since the exhaust means only needs to provide power enough to circulate gas, energy can be saved.

  Hereinafter, the present invention will be described in detail based on examples.

  FIG. 1 is a diagram showing an example of a system configuration of an etching apparatus according to an embodiment of the present invention. The etching means 10 comprises a vacuum processing chamber 11, a sample table 12 as a substrate mounting table, a high frequency power supply 13 for bias, and the like. Reference numeral 20 denotes a plasma generating means, which includes a microwave oscillator 21 for transmitting microwaves to the processing chamber, a waveguide 22, and a magnet coil 23 for generating a magnetic field in the processing chamber 11. Reference numeral 14 denotes an etching gas supply path, and a gas having a predetermined pressure is introduced into the processing chamber 11 from the etching gas supply means 30. This gas is excited by utilizing the interaction between the electric field of the microwave and the magnetic field of the magnet coil 23 to generate plasma. With this plasma, the substrate, that is, the sample 15 which is the material to be etched is etched.

  The exhaust gas after the etching process is sent from the exhaust hole 16 to the separation unit 50 via the variable conductance valve 41 of the exhaust unit 40 and the exhaust pump 42. Here, a gas effective for etching is separated. It is again supplied to the processing means 10 via the circulation / accumulation means 60 and the flow path control section 71 of the gas flow rate control means 70. The amount of the supplied gas is controlled by the controller 72. 73 is a vacuum pressure gauge. The remaining gas and solids separated by the separation means 50 are carried out of the apparatus from the discharge means 80 and processed.

  FIG. 2 shows details of the gas flow control means. The flow path control section 71 has a valve 711 provided in a passage 710 connecting the etching gas supply means 30 and the processing means 10, and flow meters 712, 713, and further, a passage connecting the circulation / accumulation means 60 and the passage 710. 714 has a valve 715 and a flow meter 716. On the other hand, the control device 72 includes a control unit 721 that performs overall control of the etching processing means. Further, a gas flow rate / pressure measuring unit 722 for measuring the gas flow rate of each passage and measuring the pressure of the processing chamber, and a gas supply control unit 723 for controlling the gas supply amount based on the outputs of the control unit and the measuring unit are provided. I have. The exhaust unit control unit 725 generates an output for driving the exhaust unit 40 based on the output of the control unit 721. The outputs of the gas supply unit 723 and the exhaust unit control unit 725 are applied to a valve drive unit 724 and a pump drive unit 726, and control signals (1) to (5) are given to the corresponding units.

  Next, the operation of the gas flow control means 70 of FIG. 2 will be described with reference to the time chart of FIG.

When the etching apparatus is started, the exhaust pump 42 is driven to exhaust gas. At this time, the controller 72 controls the pressure in the processing chamber to a predetermined pressure while monitoring the pressure in the processing chamber 11 with the vacuum gauge 73. After the startup, the exhaust pump 42 is used as a pump for circulating the etching gas. The etching is performed at time TE (about 3 minutes) at the timing shown in FIG. First, an etching gas is supplied to the processing chamber 11 from the gas supply unit 30 via the passage 710. The control device 72 opens the valve 711 at the timing shown in FIG. 3B and supplies the processing gas to the processing chamber 11.
At this time, the flow rate is measured by the flow meter 712. On the other hand, the exhaust pump 42 is driven to perform exhaust at the timing shown in FIG. At this time, the variable conductance valve 41 is controlled while monitoring the pressure in the processing chamber 11 with the vacuum gauge 73 to control the processing chamber to a predetermined pressure.

  Next, a microwave is introduced into the processing chamber 11 from the microwave oscillator 21 via the waveguide 22, the processing gas in the processing chamber is turned into plasma, and the sample 15 placed on the sample stage 12 is subjected to plasma processing.

  The exhaust gas after the plasma processing is guided to the separating means 50 via the variable conductance valve 41 and the exhaust pump 42, and the unreacted gas and the reactive gas are separated at the timing shown in FIG.

  The unreacted gas separated by the separation means is recovered in the recovery tank of the circulation / accumulation means 60 (E in FIG. 3), and further supplied with the processing gas for a time TD via a passage 714 including a flow meter 716 and an opening / closing valve 715. It is led to line 710 (FIG. 3, F).

  The control device 72 controls the valve 711 of the flow control unit 71 while comparing the unreacted gas flow rate Q2 supplied from the recovery tank of the storage device 60 and the processing gas flow rate Q1 supplied to the processing chamber, and controls the processing gas source. The shortfall Q3 is supplemented from 30. As an example, the flow rate Q1 of the processing gas is about 100 cc / min, and the flow rate Q2 is close to this, so that the shortage Q3 can be considerably small.

  Next, as the separation means 50, a method which can be most easily realized is a mechanical method without a reaction using a separator having a combination of separators 51 and 52, a check valve 53 and a pump 54 as shown in FIG. Separation (primary separation). According to this method, a substance having a large mass generated by the etching can be separated by a filter or a cyclone in the separator, and only a gas that has not contributed to the etching can be extracted. Alternatively, the separators 51 and 52 may be constituted by adsorption means. In this case, the reaction gas is adsorbed by the separator, and the unreacted gas is taken out. The separators are used alternately, and when one is adsorbed, the other is regenerated.

  As a method of further improving the utilization efficiency of the etching gas, as shown in FIG. 5, a secondary separator having a high frequency power supply 57 connected to a coil 56 and a DC power supply 59 connected to an electrode 58 has a reaction (decomposition) accompanied by a reaction (decomposition). Secondary separation). In the secondary separation, the reaction product is given an energy higher than its binding energy to separate it. By this secondary separation, the exhaust gas after the plasma treatment is converted into plasma again, a voltage is applied to the plasma-converted molecules to deflect the molecules, and the unreacted gas species is collected. In this way, the reaction product can be separated by applying energy with heat, plasma, etc., to return to the original gas.

  The solid reaction product remaining in the secondary separation is removed as a solid. For example, when 30% of the surface of an 8-inch wafer is etched to a depth of 1 μm, the volume of the solid is 9.42 mm 3, which can be accumulated in a 1-liter tank for about 100,000 sheets. .

  FIG. 6 shows a gas reaction state according to the method of the present invention. This example shows a case in which Al or Poly-Si is used for a substrate and Cl2 is used as an etching gas. The pressure of the etching gas in the processing chamber is set to 1 mmTorr, and microwaves are introduced to generate plasma. Due to the plasma, a part of the Cl2 gas is combined with the material Al to be etched to become a reaction product ClxAly. The Cl2 gas and the reaction product are separated by primary separation means, and the Cl2 gas is refluxed. On the other hand, the reaction product ClxAly is separated into solid Al and gas Cl2 by secondary separation, and the Cl2 gas is refluxed.

  The etching gas is not limited to the above example, and may be an F-based gas, a Cl-based gas, or an FH-based gas, or may be a mixed gas as the etching gas. In the case of a mixed gas, a means for further separating the mixed gas into each single gas is provided between the separating means 50 and the gas flow rate control means, and the flow rate of each gas is measured to make the replenishment gas flow rate. What is necessary is just to set and supply it to the etching processing means 10 at a predetermined mixed gas ratio. Also, the material to be etched can be widely applied, such as Si, Poly-Si, and SiO2.

  Note that it is also possible to provide a single separating and circulating means for a plurality of etching apparatuses. Further, the plasma generating means is not limited to the method using the microwave described in the embodiment, but may be another means such as a high-frequency power supply.

  Also, in a case where a film is formed by reacting a processing gas as in a CVD apparatus, in a case where the unreacted gas is exhausted, the present invention is similarly applied to the case where the unreacted gas is exhausted. Can be reused.

1 is a diagram illustrating a system configuration of an etching apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing details of gas flow control means in the system of FIG. 1. FIG. 3 is a timing chart showing the operation of the gas flow control means of FIG. FIG. 2 is a diagram illustrating an example of a separating unit in the system of FIG. 1. FIG. 4 is a diagram illustrating another example of the separating unit in the system of FIG. 1. FIG. 3 is a diagram illustrating a gas reaction in the method of the present invention.

Explanation of reference numerals

10 etching processing means, 20 plasma generating means, 30 etching gas supply means, 40 exhaust means, 50 separation means, 60 circulation / accumulation means, 70 gas flow control means.

Claims (10)

In an etching method, an etching gas is introduced into a processing chamber, the etching gas is turned into plasma, and the plasma is used to perform an etching process on a substrate placed in the processing chamber.
Exhaust gas discharged from the processing chamber along with the etching process is separated into the etching gas and solids,
An etching method, wherein the separated etching gas is circulated to the processing chamber and used for the next etching process. In an etching method, an etching gas is introduced into a processing chamber, the etching gas is turned into plasma, and the plasma is used to perform an etching process on a substrate placed in the processing chamber.
Exhaust gas discharged from the processing chamber along with the etching process is separated into the etching gas and solids,
Giving energy equal to or more than the binding energy to the solid, to separate the solid of the material to be etched and the etching gas,
The etching method, wherein the etching gas obtained by the separation and separation is circulated to the processing chamber and used for the next etching process. An etching method for introducing an etching gas from a supply source into a processing chamber, converting the etching gas into plasma, and performing an etching process on a substrate placed in the processing chamber by the plasma.
Exhaust gas discharged from the processing chamber along with the etching process is separated into the etching gas and solids,
The separated etching gas is returned to the processing chamber, and a flow rate of the etching gas to be supplied to the processing chamber is compared with a flow rate of the refluxed etching gas, and a control is performed so as to compensate for the shortage from the etching gas supply source. An etching method characterized in that:   4. The etching method according to claim 1, wherein a pump for discharging the etching gas from the processing chamber is used as a vacuum pump when starting the etching apparatus, and for circulating the etching gas after starting. An etching method characterized by being used as a pump. A processing chamber, a plasma generation unit, an etching processing unit, an etching gas supply unit, and an exhaust unit, and introducing an etching gas into the processing chamber;
The etching gas is turned into a plasma, and the etching apparatus performs an etching process on the substrate placed in the processing chamber by the plasma.
Separating means for separating the etching gas from the gas and reaction products exhausted by the exhaust means, accumulating means for accumulating the etching gas separated by the separating means, and applying the accumulated etching gas to the processing means. An etching apparatus comprising: circulating means for circulating.   The etching apparatus according to claim 5, wherein the separation unit is a filter that separates the reaction product from the etching gas exhausted from the exhaust unit.   The etching apparatus according to claim 6, wherein the separation unit is a cyclone that separates a reaction product from the etching gas exhausted from the exhaust unit.   6. The etching apparatus according to claim 5, wherein said separation means is an apparatus for applying energy equal to or more than the binding energy to the reaction product to separate the reaction product into the etching gas and the material to be etched. A processing chamber, a plasma generation unit, an etching processing unit, an etching gas supply unit, and an exhaust unit, an etching gas is introduced into the processing chamber, the etching gas is turned into plasma, and the plasma enters the processing chamber. In an etching apparatus that performs an etching process on a placed substrate,
Separating means for separating the etching gas from the gas and reaction products exhausted by the exhaust means, accumulating means for accumulating the etching gas separated by the separating means, and circulating the accumulated gas to the processing means Circulating means, and a gas flow control means,
The gas flow rate control means includes a valve and a gas flow meter provided in a first passage connecting the etching gas supply means and the processing chamber, and a valve provided in a second passage connecting the accumulation means and the first passage. An etching apparatus comprising: a gas flow meter; a pressure measuring unit that measures the pressure of the processing chamber; and a control device that controls the valve based on the gas flow rate and the pressure. The control device compares the flow rate of the etching gas supplied into the processing chamber with the flow rate of the etching gas refluxed from the storage means, and is provided in the first passage so as to compensate for the shortage from the etching gas supply means. The etching apparatus according to claim 9, further comprising a gas supply control unit configured to control the provided valve.

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