JP2016201530A - Gas supply control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily supply a gas having a desired flow rate into a chamber.SOLUTION: A gas supply control method is provided that uses a pressure control flowmeter, a first valve and a second valve provided upstream and downstream, respectively, of the pressure control flowmeter. The pressure control flowmeter includes a control valve that is connected to the first and second valves, and an orifice that is provided between the control valve and the second valve. In the gas supply control method: a volume Vof a gas supply pipe between the orifice and the control valve and a volume Vof a gas supply pipe between the orifice and the second valve satisfy V/V≥9; a pressure Pof the gas supply pipe between the orifice and the control valve and a pressure Pof the gas supply pipe between the orifice and the second valve are maintained in P>2×Pwith the gas being supplied; and the supply of the gas is controlled by controlling opening/closing of the second valve with the first valve being opened and the control valve being controlled.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a gas supply control method.

  In the semiconductor manufacturing apparatus, the substrate is finely processed by the action of a desired gas supplied into the chamber. As an apparatus used for gas flow control at that time, for example, a pressure type flow control apparatus shown in Patent Document 1 has been proposed. The pressure-type flow control device is connected to a gas supply pipe for supplying gas from a gas supply source into the chamber, and controls the flow rate of the gas flowing through the gas supply pipe by controlling the opening degree of the control valve.

JP 2004-5308 A

  However, in the control of the control valve disclosed in Patent Document 1, it takes time to supply a gas having a desired flow rate into the chamber, which is one factor that deteriorates the throughput of semiconductor manufacturing. In addition, since a gas with an uncontrolled flow rate is supplied into the chamber until a gas with a desired flow rate is supplied, microfabrication of the substrate cannot be performed satisfactorily. It has become.

  In view of the above problem, in one aspect, an object of the present invention is to quickly supply a gas having a desired flow rate into a chamber.

In order to solve the above-described problem, according to one aspect, a pressure-controlled flow meter provided in a gas supply line and a first provided in an upstream side of the pressure-controlled flow meter in the gas supply line. And a second valve provided on the downstream side of the pressure control type flow meter in the gas supply line, wherein the pressure control type flow meter A control valve connected to the first valve and the second valve, and an orifice provided between the control valve and the second valve, and a gas supply pipe between the orifice and the control valve. the volume V ₂ of the gas supply pipe between the volume V ₁ and the orifice and the second valve has a relationship of V 1 _/ V ₂ ≧ 9, the gas supply between the orifice and the control valve Of the pressure P ₂ of the gas supply pipe between the pressure P ₁ and said orifice and said second valve is maintained P _1> to 2 × P ₂ while supplying gas, opening said first valve, said A gas supply control method is provided in which gas supply is controlled by opening / closing control of the second valve while the control valve is controlled.

  According to one aspect, a gas having a desired flow rate can be rapidly supplied into the chamber.

The figure which shows an example of the whole structure of the gas supply control system concerning one Embodiment. The figure which shows an example of the gas supply control method concerning a comparative example, and the flow volume of gas. The figure which shows an example of the gas supply control method concerning one Embodiment, and the flow volume of gas. The figure which shows an example of the emitted light intensity by gas of one Embodiment and a comparative example. The figure which shows an example of the pressure in the volume ratio of the gas supply pipe | tube around the orifice concerning a comparative example. The figure which shows an example of the pressure in the volume ratio of the gas supply pipe | tube around the orifice concerning one Embodiment. The figure which shows an example of the volume ratio change and equilibrium pressure of the gas supply pipe | tube around the orifice concerning one Embodiment. The figure which shows an example of the relationship between the predetermined time T and etching rate concerning one Embodiment. The figure which shows the appropriate range of the volume ratio of the gas supply pipe | tube around the orifice concerning one Embodiment. The flowchart which shows an example of the rapid alternating process using the gas supply control method of one Embodiment. The figure for demonstrating the gas supply control method concerning the modification of one Embodiment. The figure which shows an example of the whole structure of the gas supply control system concerning the modification of one Embodiment. The flowchart which shows an example of the rapid alternating process using the gas supply control method of the modification of one Embodiment. The flowchart which shows an example of the rapid alternating process using the gas supply control method of the modification of one Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, in this specification and drawing, about the substantially same structure, the duplicate description is abbreviate | omitted by attaching | subjecting the same code | symbol.

[Overall configuration of gas supply control system]
First, an example of the overall configuration of a gas supply control system 1 according to an embodiment of the present invention will be described with reference to FIG. The gas supply control system 1 is a system that controls the gas supplied to the semiconductor manufacturing apparatus 10.
(Configuration example of semiconductor manufacturing equipment)
The semiconductor manufacturing apparatus 10 has a cylindrical chamber C made of aluminum whose surface is anodized (anodized). Chamber C is grounded. A mounting table 12 is provided inside the chamber C. The mounting table 12 mounts the wafer W thereon.

  A high frequency power supply 13 for exciting plasma is connected to the mounting table 12 through a matching unit 13a. For example, the high frequency power source 13 applies a high frequency power of a frequency suitable for generating plasma in the chamber C, for example, 60 MHz, to the mounting table 12. In this way, the mounting table 12 functions as a lower electrode while mounting the wafer W thereon. The matching unit 13a matches the load impedance to the internal (or output) impedance of the high-frequency power source 13. The matching unit 13a functions so that the internal impedance of the high-frequency power source 13 and the load impedance seem to coincide when plasma is generated in the chamber C.

  On the ceiling of the chamber C, a gas shower head 11 is provided as an upper electrode. Thereby, high frequency power from the high frequency power supply 13 is capacitively applied between the mounting table 12 and the gas shower head 11. The gas is introduced from the gas introduction port 14 of the gas shower head 11 and is supplied into the chamber C through the gas buffer space 11b and from a large number of gas vent holes 11a.

The semiconductor manufacturing apparatus 10 performs fine processing on the wafer W by the action of a desired gas supplied into the chamber C. In this case, the pressure type flow rate control device 20 is used for the flow rate control of the gas. (Configuration example of pressure type flow control device)
The pressure type flow control device 20 is connected to a gas supply line 15 for supplying gas from the gas supply source 30 to the semiconductor manufacturing apparatus 10. The pressure type flow rate control device 20 controls the flow rate of the gas supplied into the chamber C by controlling the opening degree of the control valve 21 to flow through the gas supply line 15. An example of the control valve 21 is an electromagnetic valve drive type metal diaphragm valve. The pressure type flow control device 20 includes a control valve 21, a control circuit 22 for controlling the opening degree of the control valve 21, an orifice 23, pressure gauges 24 and 25, a gas supply pipe 15a, and a gas supply pipe 15b. The orifice 23 is provided between the gas supply pipe 15a and the gas supply pipe 15b. The gas supply pipe 15 a is a gas pipe from the orifice 23 to the control valve 21. The gas supply pipe 15b is a gas pipe between the orifice 23 and the second valve VL2. The gas supply pipe 15 a and the gas supply pipe 15 b are connected to the gas supply line 15. The pressure type flow control device 20 is an example of a pressure control flow meter provided in the gas supply line.

The pressure in the gas supply pipe 15a and _{P 1,} the volume and _{V 1.} The pressure in the gas supply pipe 15b and _{P 2,} the volume and _{V 2.} When the pressures P ₁ and P _{2 in} the gas supply pipe 15a and the gas supply pipe 15b inside the pressure type flow control device 20 are controlled so as to substantially satisfy the critical expansion pressure condition P ₁ > 2 × P ₂ , The gas flow rate Q flowing through the orifice 23 is determined only by the pressure P ₁ upstream of the orifice 23 and is represented by the following relational expression (1).
Q = CP ₁ (1)
The pressure type flow rate control device 20 utilizes the above formula (1), and the pressure P ₁ is adjusted by the control valve 21 so that the gas flow rate Q downstream of the orifice 23 matches the process conditions. Control to keep the value. In the above formula (1), C is a constant determined by the diameter of the orifice 23 and the gas temperature. Further, the pressure P ₁ and the pressure P ₂ are measured by the pressure gauge 24 and the pressure gauge 25, respectively.

  A first valve VL1 is disposed upstream of the pressure type flow control device 20 (gas supply source side), and a second valve VL2 is disposed downstream of the pressure type flow control device 20 (semiconductor manufacturing apparatus side). Has been. The first valve VL1 and the second valve VL2 can be controlled to be fully open or fully closed.

  When processing such as etching is performed in the semiconductor manufacturing apparatus 10 having such a configuration, first, the wafer W is loaded into the chamber C and mounted on the mounting table 12. The pressure in the chamber C is reduced to a vacuum state. The gas output from the gas supply source 30 is introduced into the chamber C from the gas shower head 11 in the form of a shower. A predetermined high frequency power output from the high frequency power supply 13 is applied to the mounting table 12.

  The wafer W is subjected to processing such as plasma etching by the action of plasma generated by ionizing and dissociating the introduced gas with high frequency power. After the processing such as plasma etching is completed, the wafer W is unloaded from the chamber C. Note that the semiconductor manufacturing apparatus 10 is not necessarily limited to processing using plasma, and the wafer W may be finely processed by heat treatment or the like.

[Gas supply control method]
Next, the gas supply control method according to the comparative example will be described with reference to FIG. 2, and then the gas supply control method according to the present embodiment will be described with reference to FIG. In the gas supply control method according to the comparative example, the gas supply is controlled by opening / closing control of each valve shown in FIG.

In FIG. 2A, the horizontal axis indicates time, and the vertical axis indicates the control states of the first valve VL1, the second valve VL2, and the control valve 21, respectively. In FIG. 2B, the horizontal axis represents time, and the vertical axis represents the pressures P ₁ and P ₂ of the pressure flow control device (FCS). In FIG. 2C, the horizontal axis represents time, and the vertical axis represents the gas flow rate flowing through the second valve VL2.

  Each valve is controlled in the order of step 1 → step 2 → step 3 → step 2 → step 3. Steps 2 and 3 are repeated a predetermined number of times.

  The first valve VL1 and the second valve VL2 can be controlled to be fully opened or fully closed. The opening of the control valve 21 can be adjusted from fully open to fully closed. When the first valve VL1 and the second valve VL2 are “OPEN”, it indicates that the valves are fully open. Further, when the first valve VL1 and the second valve VL2 are “CLOSE”, it indicates that the valves are fully closed. When the control valve 21 is “in control”, the opening degree of the control valve 21 is controlled by the control of the control circuit 22, and a gas having a flow rate corresponding to the opening degree is supplied. When the control valve 21 is “control stop”, the control valve 21 is fully closed, and the gas supply is stopped.

The state of each valve in each step is shown below.
(Step 1)
In step 1, the first valve VL1 and the second valve VL2 are controlled to be fully closed, the control of the control valve 21 is stopped, and the gas supply is stopped.
(Step 2)
In Step 2, the first valve VL1 and the second valve VL2 are controlled to be fully opened, and then the control valve 21 is under control and gas supply is started.

The order of the opening and closing operations of the first valve VL1 and the second valve VL2 may be simultaneous, or the opening operation of the first valve VL1 is performed after a predetermined time has elapsed since the opening of the second valve VL2. You may go. The control valve 21 is controlled after the opening operation of the first valve VL1 and the second valve VL2 is completed. Therefore, after the opening operation of the first valve VL1 and the second valve VL2 is completed, the control operation of the control valve 21 is started after a predetermined time T has elapsed. In the embodiment, the predetermined time T is 200 msec, but is not limited thereto.
(Step 3)
In Step 3, the first valve VL1 and the second valve VL2 are controlled to be fully closed, and then the control of the control valve 21 is stopped again, and the gas supply is stopped.

For the control of each valve in the above steps, the pressures P ₁ and P _{2 of the} pressure type flow control device 20 (FCS) shown in FIG. 2B and the second valve VL2 in FIG. The flowing gas flow rate will be described.

Since the critical expansion pressure condition P ₁ > 2 × P ₂ was satisfied before the gas was stopped, in step 1, after the gas supply was stopped, the gas supply pipe 15a and the gas supply pipe 15b would be in an equilibrium state. since the movement of gas occurs, the pressure P _1, as shown in FIG. 2 (b) gradually decreases, the pressure P ₂ increases gradually. Further, as shown in FIG. 2C, no gas flows through the second valve VL2.

In step 2, first, the first valve VL1 and the second valve VL2 are controlled to be fully opened. As a result, the pressures P ₁ and P ₂ are temporarily reduced as shown in FIG. 2B, and the gas supply pipe 15a and the gas supply pipe are provided in the second valve VL2 as shown in FIG. After the gas remaining in 15b flows, it decreases. Thereafter, as shown in FIG. 2 (a), since the control valve 21 of the pressure type flow rate control device 20 starts the control pressure P ₁ shown in FIG. 2 (b) is increased, the second valve VL2 The desired flow rate will flow.

Thereafter, when the control valve 21 is under control, the pressures P ₁ and P ₂ of the gas supply pipe 15a and the gas supply pipe 15b are controlled to be constant as shown in FIG. As shown, the gas flow rate passing through the second valve VL2 is controlled to be constant. That is, when the control valve 21 is under control, the flow rate of the gas supplied to the chamber C is controlled to a predetermined amount.

In Step 3, after the first valve VL1 and the second valve VL2 are controlled to be fully opened, the control valve 21 is fully closed, and the gas supply is stopped. As a result, gas movement occurs even if the gas supply pipe 15a and the gas supply pipe 15b are in an equilibrium state. As a result, as shown in FIG. 2 (b), the pressure _{P 1} of the gas supply pipe 15a is decreased, the pressure _{P 2} of the gas supply pipe 15b is moved in the direction to increase. In step 3, as shown in FIG. 2C, no gas flows through the second valve VL2.

  FIG. 4 shows a temporal change in the flow rate of the gas supplied into the chamber C by the emission intensity in the chamber C. When the emission intensity in the chamber C increases, the gas flow rate increases. Moreover, it shows that gas flow volume is falling, when emitted light intensity becomes low.

  In the comparative example, as shown in step 2 of FIG. 2A, (1) the first valve VL1 and the second valve VL2 are fully opened, and (2) the control valve 21 is under control thereafter. become. In the comparative example, the supply of gas is started when the second valve VL2 is opened. Therefore, at a predetermined time T from when the first valve VL1 and the second valve VL2 are opened to when the control valve 21 is under control, the first valve VL1 and the second valve VL1 shown in FIG. The gas G remaining in the gas supply pipe between the two valves VL2 flows through the second valve VL2 and is supplied to the chamber C. When the control valve 21 starts control, the gas controlled to a predetermined flow rate flows through the second valve VL2 and is supplied to the chamber C. Thus, in the comparative example, after the rising of the two stages I1 and I2 in FIG. 4 occurs in the gas flow rate supplied into the chamber C by the two-stage control of (1) and (2) in Step 2, It is controlled to a predetermined flow rate.

  The rising height and inclination of the gas flow rate of the first stage I1 before the control of the control valve 21 shown in FIG. 4 is determined by the residual gas in the pressure type flow rate control device 20. The state of this residual gas differs depending on the usage state of the pressure type flow control device 20 immediately before the start of the current gas supply and the individual difference of the pressure type flow control device 20. For this reason, it is difficult to completely manage the rising of the gas flow rate in the first stage I1. Therefore, in particular, it is more difficult to completely control the emission intensity waveform of the first stage I1, that is, the control of the gas flow rate of the first stage I1 than the control of the gas flow rate of the second stage I2.

As one method for eliminating the rise of the first stage I1 of the gas flow rate, there is a method of reducing the variation of the pressure P ₁ of while stopping the supply of gas. One of means for realizing the method is the gas supply control method according to the present embodiment.

  In the gas supply control method according to the present embodiment, the valve used for controlling the gas flow rate is one of the second valves VL2. As a result, it is possible to suppress a steep change at the time of gas supply in the chamber C, such that the two stages I1 and I2 rise in the flow rate of the gas supplied into the chamber C.

Specifically, the gas supply control method according to the present embodiment controls each valve as shown in FIG. The state of each valve in each step is shown below.
(Step 1)
In Step 1, the first valve VL1 is controlled to be fully opened, and the control valve 21 is under control. The second valve VL2 is controlled to be fully closed, and the gas supply is stopped.
(Step 2)
In step 2, the first valve VL1 is controlled to be fully opened, and the control valve 21 is maintained under control. The second valve VL2 is controlled to be fully opened, and gas supply starts.
(Step 3)
In step 3, the first valve VL1 is controlled to be fully opened, and the control valve 21 is maintained under control. The second valve VL2 is controlled to be fully closed, and the gas supply is stopped.

For the control of each valve in the above steps, the pressures P ₁ and P _{2 of the} pressure type flow control device 20 (FCS) shown in FIG. 3B and the second valve VL 2 in FIG. The flowing gas flow rate will be described. In the present embodiment, the first valve VL1 is controlled to be opened in all steps, and the control valve 21 is maintained during the control. Therefore, the pressure _{P 1} of the gas supply pipe 15a is constant.

Further, in the present embodiment, the gas flow through the pressure P ₂ and the second valve VL2 of the gas supply pipe 15b varies in response to the opening and closing of the second valve VL2. That is, since the step 1 in the second valve VL2 of the present embodiment shown in (a) FIG. 3 is in the closed state, the pressure P ₂ of the gas supply pipe 15b as shown in FIG. 3 (b) becomes higher It is maintained when it reaches the same pressure as the pressure P ₁ on the pressure. Further, as shown in FIG. 3C, no gas flows through the second valve VL2. In step 2 the second valve VL2 is opened, the pressure P ₂ is lowered as shown in (b) of FIG. 3 in response thereto, is maintained at a predetermined pressure. Further, as shown in FIG. 3C, a gas having a predetermined flow rate flows through the second valve VL2. In step 3, it closed second valve VL2 again, the pressure P ₂ of the gas supply pipe 15b as shown in FIG. 3 (b) is higher, is maintained when it reaches the same pressure as the pressure P ₁ on the pressure . As shown in FIG. 3C, no gas flows through the second valve VL2.

  According to this, in the present embodiment, the flow rate of the gas flowing through the second valve VL2 becomes constant according to the opening / closing of the second valve VL2, and the gas having a controlled flow rate is supplied to the chamber C. In this embodiment, since the first valve VL1 is always controlled to be open and the control valve 21 is always controlled during control, there is no uncontrollable gas remaining in the pressure type flow control device 20, This is because the gas flow rate following the opening and closing of the second valve VL2 can be controlled.

  As described above, the gas supply control method according to this embodiment always opens the first valve VL1 and always controls the control valve 21 during control. As a result, a part of the gas existing downstream of the orifice 23 whose conductance is reduced when the second valve VL2 is opened and gas supply is started smoothly enters the chamber C without passing through the orifice 23. Supplied. Thereby, as soon as the gas supply is started, the gas is supplied into the chamber C. As a result, the two-stage rising of the gas flow rate as shown in the comparative example of FIG. 4 can be eliminated.

However, in the above gas supply control method, when the variation of the pressure P ₁ and the pressure P ₂ is but are not no longer occur, which is repeated a very short period at a flow rate control (ON → OFF → ON → ... ) is the pressure P ₁ and the pressure P ₂ does not reach the equilibrium state, it is difficult to avoid the rise of in two stages.

Therefore, in this embodiment, the ratio V ₁ / V ₂ of the volumes V ₁ and V ₂ in the gas supply pipe 15a and the gas supply pipe 15b of the pressure type flow control device 20 using the gas supply control method described above is optimized. To do. By performing the gas supply control method of the present embodiment using the pressure type flow rate control device 20 in which the ratio V ₁ / V _{2 of} the volumes V ₁ and V ₂ is optimized as described above, the residual gas is caused. It is possible to completely avoid the rising of the gas flow rate in two stages. Hereinafter, the optimization of the volume ratio V ₁ / V ₂ in the gas supply pipe 15a and the gas supply pipe 15b will be described.

[Optimization of gas supply pipe volume ratio]
In the present embodiment, the arrangement of the orifice 23 in the pressure type flow control device 20, the control valve 21 and the second valve VL2 before and after the orifice 23 is changed, and the volume ratio V ₁ / V of the gas supply pipe 15a and the gas supply pipe 15b is changed. to optimize the V _2. Specifically, in the comparative example, whereas the volume ratio V _{1 /} V ₂ of the gas supply pipe 15a and the gas supply pipe 15b is 3/2, in the present embodiment, the gas supply pipe 15a and the gas supply pipe volume ratio _V 1 / _{V 2} 15b changes the arrangement of the control valve 21 and second valve VL2 to the above 9/1.

For example, on condition that the pressures P ₁ and P ₂ substantially satisfy the critical expansion pressure condition P ₁ > 2 × P ₂ , the volume ratio V ₁ / V ₂ of the gas supply pipe 15a and the gas supply pipe 15b is 3/2. Set to. In this case, FIG. 5 shows the states of the pressures P ₁ and P ₂ after the gas supply is stopped, that is, after the control valve 21 and the second valve VL2 are closed. In Figure 5, the variation of the pressure P ₁ of the gas supply pipe 15a is large, it takes time to stabilize. As a result, the peak of the gas corresponding to the pressure P ₁ after the change in the control of the start and stop of gas supply is generated, it is difficult to flow control of the gas. Also, when changing the gas flow rate, the pressure P ₁ is takes time to stabilize.

On the other hand, on the condition that the pressures P ₁ and P ₂ substantially satisfy the critical expansion pressure condition P ₁ > 2 × P ₂ , the volume ratio V ₁ / V ₂ of the gas supply pipe 15a and the gas supply pipe 15b is set to 90/1. Set to. In this case, FIG. 6 shows the states of the pressures P ₁ and P ₂ after the gas supply is stopped, that is, after the control valve 21 and the second valve VL2 are closed. In Figure 6, the pressure P ₁ of the gas supply pipe 15a is not substantially vary, it can be seen that immediately stabilized. This also when changing the gas flow rate, the pressure P ₁ indicating that a shorter time to stabilize.

Curve I3 of the light emitting intensity in this embodiment of FIG. 4, present by using a pressure type flow rate control device 20 the volume ratio of the gas supply pipe 15a and the gas supply pipe 15b V _{1 /} V ₂ is set to 90/1 The light emission intensity | strength by the gas in the chamber C when gas is supplied with the gas supply control method of embodiment is shown. According to this, since the time until the pressure P ₁ is stabilized can be shortened by setting the volume ratio V ₁ / V ₂ of the gas supply pipe 15 a and the gas supply pipe 15 b to 90/1, the gas supply can be performed. After being started, the gas is smoothly supplied into the chamber C. Thereby, the two-stage rising of the gas flow rate as shown in the comparative example of FIG. 4 can be eliminated.

[Equilibrium pressure P ₁ ]
FIG. 7 is a graph plotting the pressure in an equilibrium state with respect to the initial pressure of the pressure P ₁ in the gas supply pipe 15a when the volume ratio V ₁ / V ₂ of the gas supply pipe 15a and the gas supply pipe 15b is changed. . As described above, the equilibrium pressure / initial pressure of the pressure P ₁ when the volume ratio V ₁ / V ₂ of the gas supply pipe 15 a and the gas supply pipe 15 b is set to 90/1 is represented by Re in FIG. As shown by, the value is almost 100%. Specifically, with respect to the plotted values shown in FIG. 7, the equilibrium pressure / initial pressure of the pressure P ₁ is 62% when the volume ratio V ₁ / V ₂ is 1.5, and the volume ratio V ₁ / V ₂ is 3. 75% 0, 90% when the volume ratio _V 1 / _{V 2} 9.0 95% when the volume ratio _V 1 / _{V 2} is 18.0, the volume ratio _V 1 / _{V 2} is 30.0 97% and 99% when the volume ratio V ₁ / V ₂ is 90.0.

At this time, when the volume ratio V ₁ / V ₂ is set to 90/1, the etching rate E / R when the etching process is performed in the chamber C and the volume ratio V ₁ / V ₂ are set to 3/2. In this case, the variation from the etching rate E / R when the etching process is performed in the chamber C is 20%.

Since it is ideal that the volume ratio V ₁ / V ₂ is set to 90/1 and the rising waveforms of the two stages I1 and I2 shown in the comparative example of FIG. 4 are not observed, the etching rate E from here / variation of R a to keep within 5%, it is preferable that the ratio of the pressure P ₁ of the equilibrium with respect to the initial pressure to 90% to 100%. That is, the volume ratio _V 1 / _{V 2} of the gas supply pipe 15a and the gas supply pipe 15b may be set to more than 9/1.

That is, the volumes V ₁ and V ₂ may be set so that the volume ratio V ₁ : V ₂ in FIG. 9 is a portion (dot and hatched portion) of 9: 1 or more. However, it is preferable to set the volumes V ₁ and V ₂ so that the volume ratio V ₁ : V ₂ is 200: 1 or less due to physical limitations on the processing of the gas supply pipes 15a and 15b. Actually, when the volume ratio V ₁ : V ₂ is 9: 1 or more and 200: 1 or less and the volume V ₁ is in the range of 0.09 to 2.0 (cc), the volume V ₂ is 0. .01 to 0.2 (cc), that is, the area Ar is an effective range when the ratio of the volume V ₁ / V ₂ is set.

  As described above, in this embodiment, the gas supply to the chamber C and the gas supply stoppage are performed by the opening / closing operation of the second valve VL2 provided on the downstream side of the orifice 23 in the pressure type flow control device 20. Take control. At that time, the volume from the orifice 23 to the control valve 21 and the second valve VL2 before and after the orifice 23 is reduced in comparison with the comparative example in order to relieve the pressure change at the time of gas stop due to the structure peculiar to the pressure type flow control device 20. Make it one or more orders of magnitude smaller.

  According to this, the gas supplied into the chamber C can be quickly started up to a predetermined flow rate using the pressure type flow rate control device 20. According to the present embodiment, by improving the gas responsiveness in this way, the gas can be switched at a high speed. That is, the gas supply control method according to the present embodiment using the pressure type flow rate control device 20 according to the present embodiment is effective for a process (Gas Pulse) in which gas supply and gas supply stop are repeated at high speed.

  Further, in this embodiment, since the gas responsiveness is improved, the time until the gas flow rate is stabilized in the chamber C can be shortened, and the throughput can be improved.

  When the predetermined time T in FIG. 2A described above becomes longer, the flow rate of the gas supplied to the chamber C becomes stable. However, the actual gas supply time is shortened when the gas supply valve is open. As a result, the etching rate decreases as the predetermined time T increases. FIG. 8 shows an example of the relationship between the predetermined time T and the etching rate according to the present embodiment. The horizontal axis of FIG. 8 indicates the ratio T / S of the predetermined time T to the time S of Step 2. The vertical axis | shaft of FIG. 8 shows the etching rate (E / R) with respect to T / S.

  According to this, the etching rate becomes lower as the predetermined time T becomes longer. When (ST) / S is smaller than 90%, that is, when T / S is larger than 0.1, a decrease in etching rate cannot be ignored. Therefore, the predetermined time T needs to be 1/10 or less of the step time S.

  Further, in this embodiment, after the gas supply is started by the control of the second valve VL2, the flow rate of the gas supplied to the chamber C can be quickly stabilized at a desired flow rate. For this reason, by setting the matching unit 13a to the matching position after the flow rate is stabilized in advance, the reflected wave of the high frequency power output from the high frequency power source 13 can be suppressed, and the processing stability in the semiconductor manufacturing apparatus 10 can be suppressed. Can be improved.

  Furthermore, in this embodiment, the gas of non-control information is not introduced into the chamber C as in the comparative example. For this reason, variations in gas supply into the chamber C due to individual differences in the pressure type flow control device 20 and individual differences in the semiconductor manufacturing apparatus 10 can be absorbed, and the semiconductor manufacturing apparatus 10 can stably perform processing.

[Rapid alternating process]
Finally, as an example of a process that repeats gas supply and gas supply stop at high speed, a rapid alternating process will be briefly described with reference to FIG. In the rapid alternating process using the gas supply control method of this embodiment shown in FIG. 10, the etching process and the deposition process are executed alternately and rapidly. However, this is an example of a rapid alternating process, and the type of process is not limited to this. Further, during the rapid alternating process, the first valve VL1 is always controlled to be opened, and the control valve 21 is always controlled during the control. The rapid alternating process shown in FIG. 10 is controlled by the control circuit 22.

  When the process of FIG. 10 is started, first, the second valve VL2 is controlled to be opened, and the first gas is introduced (step S10). Next, high frequency power is applied, and an etching process is executed with the first gas (step S12). Next, the second valve VL2 is controlled to be closed (step S14).

  Next, the second valve VL2 is controlled to be opened, and the second gas is introduced (step S16). Next, high frequency power is applied, and a deposition process is executed with the second gas (step S18). Next, the second valve VL2 is controlled to be closed (step S20).

  Next, it is determined whether a further rapid alternating process cycle is necessary (step S22). If it is determined that the cycle is necessary, the process returns to step S10 and the processes of steps S10 to S22 are repeated. If it is determined in step S22 that a further rapid alternating process cycle is not required, the process ends.

  According to the rapid alternating process according to the present embodiment, a gas having a predetermined flow rate is promptly supplied into the chamber C following the control of the opening and closing of the second valve VL2, so that a good process can be realized. Further, it is possible to eliminate the control in consideration of the time until the gas reaches the chamber C. As described above, the gas supply control method of this embodiment that improves the gas responsiveness can be effectively used particularly in the rapid alternating process in which the gas supply and the stop of the gas supply are repeated at high speed.

  However, regarding the allowable range of the predetermined time T with respect to the time S of Step 2 in FIG. 2A, as shown in FIG. 8, the longer the predetermined time T (the larger T / S), the etching rate (E / R). ) Is lower. When (ST) / S is smaller than 90%, that is, when T / S is larger than 0.1, a decrease in etching rate cannot be ignored. Therefore, the predetermined time T needs to be 1/10 or less of the step time S.

(Modification)
Next, an example of a gas supply control method according to a modification of the present embodiment will be described with reference to FIGS. FIG. 11 is a diagram for explaining a gas supply control method according to a modification of the present embodiment. FIG. 12 is a diagram illustrating an example of an overall configuration of a gas supply control system according to a modification of the present embodiment.

As described above, in the gas supply control method according to the present embodiment, it is possible to improve the stability and increase the speed in the process of switching the gas at high speed. However, as shown in FIG. 11 (a), the first gas is supplied in step 2 following step 1, and the second gas is supplied in step 4 after the gas supply is stopped in step 3. In this case, a problem occurs when the flow rate of the first gas is larger than the flow rate of the second gas. That is, at the beginning of the step 4 of flowing the second gas, the flow rate of the gas flowing to the second valve VL2 cannot be controlled, the spike S is generated, and the stability and controllability when supplying the gas are deteriorated. This is the Step 2 in the first step 3 after completion of the supply of gas pressure in the gas supply pipe 15a and P _1, the gas supply pipe 15a required for supplying the second gas in Step 4 When the pressure is P ₁ ′, the flow rate of the first gas is larger than the flow rate of the second gas, and therefore P ₁ > P ₁ ′. This said that same for the pressure in the gas supply pipe 15b, the pressure in the gas supply pipe 15b in step 3 and P _2, when the pressure of the gas supply pipe 15b necessary in Step 4 was P _{2 '} And P ₂ > P ₂ ′. Thus, at the start of step 4, the pressure P ₁ necessary for a second gas supply which is sealed in the gas supply pipe 15a and the gas supply pipe 15b _'and the pressure P _2' of the high pressure P ₁ and the pressure P ₂ than Gas spouts out. As a result, at the start of step 4 immediately after switching from step 3 to step 4, the flow rate of the gas flowing through the second valve VL2 increases and a spike S is generated.

  Therefore, in the gas supply control system 1 according to the modification of the present embodiment, as shown in FIG. 12, a vacuum line 28 is provided in the gas supply pipe 15a between the control valve 21 and the second valve VL2. The evacuation line 28 is provided with a evacuation valve VL3, and the evacuation by the exhaust device 29 connected to the evacuation line 28 is controlled by opening and closing the evacuation valve VL3.

Specifically, the vacuuming valve VL3 is controlled to open in Step 3 between Step 2 and Step 4 in FIG. As a result, the inside of the gas supply pipe 15a and the gas supply pipe 15b is evacuated by the exhaust device 29, so that the pressure P ₁ of the gas supply pipe 15a in step 3 ≦ the pressure P ₁ ′ of the gas supply pipe 15a in step 4; Then, the pressure P ₂ of the gas supply pipe 15b in step 3 ≦ the pressure P ₂ ′ of the gas supply pipe 15b in step 4 is satisfied. Therefore, even when the flow rate of the first gas is larger than the flow rate of the second gas, the flow rate of the gas flowing through the second valve VL2 in FIG. The spike S is not generated. Thereby, even in the process of supplying gases having different flow rates, the stability and controllability during the gas supply can be further improved.

[Rapid alternating process]
Next, a rapid alternating process according to a modification of the present embodiment will be briefly described with reference to FIG. In the rapid alternating process using the gas supply control method of the modification of the present embodiment shown in FIG. 13, the etching process and the deposition process are alternately and rapidly performed. The rapid alternating process shown in FIG. 13 is controlled by the control circuit 22.

  When the process of FIG. 13 is started, first, the second valve VL2 is controlled to be opened, and the first gas is introduced (step S10). Next, high frequency power is applied, and an etching process is executed with the first gas (step S12). Next, the second valve VL2 is controlled to be closed, and the gas supply pipe 15a and the gas supply pipe 15b are evacuated while the gas is not supplied (step S30).

  Next, the second valve VL2 is controlled to be opened, and the second gas is introduced (step S16). Next, high frequency power is applied, and a deposition process is executed with the second gas (step S18). Next, the second valve VL2 is controlled to be closed, and the gas supply pipe 15a and the gas supply pipe 15b are evacuated while the gas is not supplied (step S32).

  Next, it is determined whether a further rapid alternating process cycle is necessary (step S22). If it is determined that the cycle is necessary, the process returns to step S10 and the processes of steps S10 to S22 are repeated. If it is determined in step S22 that a further rapid alternating process cycle is not required, the process ends.

  According to the rapid alternating process according to the modification of the present embodiment, the opening and closing of the second valve VL2 is controlled and the gas supply pipe 15a and the gas supply pipe 15b are evacuated. As a result, even when processes with different gas flow rates are performed before and after, a high-pressure gas is exhausted from the vacuum line 28 while no gas is supplied, and a small flow rate gas is supplied in the next step. Even if it exists, the gas of predetermined flow rate can be rapidly supplied in the chamber C. For this reason, according to the rapid alternating process concerning a modification, stability and controllability in supply of gas are further improved, and a good process can be realized. In particular, the gas supply control method according to the modification of the present embodiment, in which the gas responsiveness is improved, can be effectively used in a rapid alternating process in which gas supply and gas supply stop are repeated at high speed.

[Variation of rapid alternating process]
Next, variations of the rapid alternating process according to the modification of the present embodiment will be briefly described with reference to FIG. In the rapid alternating process using the gas supply control method of the modified example of the present embodiment shown in FIG. 14, the etching process and the deposition process are alternately and rapidly executed. The rapid alternating process shown in FIG. 14 is controlled by the control circuit 22.

  When the process of FIG. 14 is started, first, the second valve VL2 is controlled to be opened, and the first gas is introduced (step S10). Next, high frequency power is applied, and an etching process is executed with the first gas (step S12). Next, the second valve VL2 is controlled to be closed (step S14).

  Next, it is determined whether or not the flow rate of the first gas is higher than the flow rate of the second gas (step S40). When the flow rate of the first gas is higher than the flow rate of the second gas, the gas supply pipe 15a and the gas supply pipe 15b are evacuated while the gas is not supplied (step S42). If the flow rate of the first gas is less than or equal to the flow rate of the second gas, evacuation is not performed.

  Next, the second valve VL2 is controlled to be opened, and the second gas is introduced (step S16). Next, high frequency power is applied, and a deposition process is executed with the second gas (step S18). Next, the second valve VL2 is controlled to be closed (step S20).

  Next, it is determined whether a further rapid alternating process cycle is necessary (step S22), and if it is determined that it is necessary, it is determined whether the flow rate of the first gas is higher than the flow rate of the second gas. (Step S44). When the flow rate of the first gas is higher than the flow rate of the second gas, the gas supply pipe 15a and the gas supply pipe 15b are evacuated while the gas is not supplied (step S42), and then the process returns to step S10 and returns to step S10. The subsequent processing is repeated. If the flow rate of the first gas is less than or equal to the flow rate of the second gas, the evacuation is not performed, and then the process returns to step S10 and the processes after step S10 are repeated.

  On the other hand, if it is determined in step S22 that a further rapid alternating process cycle is not required, the process ends.

  According to the variation of the rapid alternating process according to the modification of the present embodiment, the gas supply pipe 15a and the gas supply are performed while the gas is not supplied only when the flow rate of the first gas is larger than the flow rate of the second gas. The tube 15b is evacuated. Thereby, when processes with different gas flow rates are performed before and after, a gas with a predetermined flow rate is quickly supplied into the chamber C. For this reason, according to the rapid alternating process concerning a modification, stability and controllability in supply of gas are further improved, and a good process can be realized. Further, when the flow rate of the first gas is smaller than the flow rate of the second gas, it is predicted that the spike S is unlikely to occur, and the gas supply is performed in the step in which no gas is supplied (for example, step 3 in FIG. 11). The tube 15a and the gas supply tube 15b are not evacuated. Thereby, compared with the rapid alternating process shown in FIG. 13, the time of step 3 can be shortened and a throughput can be raised.

  As mentioned above, although the gas supply control method was demonstrated by the said embodiment, the gas supply control method concerning this invention is not limited to the said embodiment, A various deformation | transformation and improvement are possible within the scope of the present invention. . The matters described in the above embodiments can be combined within a consistent range.

  For example, a semiconductor manufacturing apparatus using the gas supply control method according to the present invention uses a capacitively coupled plasma (CCP) apparatus, an inductively coupled plasma (ICP) apparatus, and a radial line slot antenna. It may be a plasma processing apparatus, a helicon wave excited plasma (HWP) apparatus, an electron cyclotron resonance plasma (ECR) apparatus, or the like.

  The substrate processed by the semiconductor manufacturing apparatus according to the present invention is not limited to a wafer, and may be a large substrate for a flat panel display, an EL element, or a substrate for a solar cell, for example.

1: Gas supply control system 10: Semiconductor manufacturing equipment 11: Gas shower head (upper electrode)
12: Mounting table (lower electrode)
13: High-frequency power supply 15: Gas supply line 15a, 15b: Gas supply pipe 20: Pressure type flow rate control device 21: Control valve 22: Control circuit 23: Orifice 24, 25: Pressure gauge 30: Gas supply source VL1: First Valve VL2: Second valve C: Chamber

Claims (5)

A pressure-controlled flow meter provided in the gas supply line; a first valve provided upstream of the pressure-controlled flow meter in the gas supply line; and the pressure-controlled flow meter in the gas supply line A gas supply control method using a second valve provided on the downstream side of the
The pressure-controlled flow meter has a control valve connected to the first valve and the second valve, and an orifice provided between the control valve and the second valve,
And the volume V ₁ of the gas supply pipe between the control valve and the orifice, and the volume V ₂ of the gas supply pipe between said orifice second valve, the relationship between V 1 _/ V ₂ ≧ 9 Have
The pressure P ₁ of the gas supply pipe between the control valve and the orifice, and the pressure P ₂ of the gas supply pipe between said second valve and said orifice, while supplying gas P _1> 2 × P ₂ is maintained,
Controlling the supply of gas by opening and closing the second valve while opening the first valve and controlling the control valve;
Gas supply control method. The volume V ₁ and the volume V ₂ have a relationship of V ₁ / V ₂ ≦ 200,
The gas supply control method according to claim 1. The first valve is opened, and the first valve and the second gas are alternately supplied by opening / closing control of the second valve in a state where the control valve is controlled, and the process using the first gas and the process Alternately performing the process with the second gas,
The gas supply control method according to claim 1 or 2. In the step of not supplying a gas between the step of supplying the first gas and the step of supplying the second gas, an inside of a gas supply pipe between the second valve and the control valve is provided. Evacuate,
The gas supply control method according to claim 3. When the flow rate of the first gas is higher than the flow rate of the second gas, the inside of the gas supply pipe between the second valve and the control valve is evacuated in the step of not supplying the gas. ,
The gas supply control method according to claim 4.

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