JP3311762B2 - Mass flow controller and semiconductor device manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mass flow controller (mass flow controller), and more particularly to a method for adjusting a gas flow rate used in a semiconductor manufacturing apparatus such as a dry etching apparatus, a CVD apparatus, an ion implantation apparatus, and a sputtering apparatus. It relates to a mass flow controller to be controlled.

[0002] In recent years, the semiconductor industry has been increasingly integrated,
There is also a demand for higher performance in semiconductor manufacturing equipment.
As one of the requirements, it is necessary to improve the reliability of a mass flow controller that controls a gas flow rate, which is one of the important parameters in semiconductor manufacturing.

[0003]

2. Description of the Related Art FIG. 3 is an explanatory view of a conventional example. In the figure, 80 is the gas flow path body, 81 is the flow sensor, 82 is the bypass, 83 is the sensor tube, 84 is the resistance wire, 85 is the bridge circuit, 86 is the output signal, 87 is the comparison circuit, and 88 is the setting signal , 89 is a control circuit, 90 is a valve, 91 is a variable orifice, and 92 is a valve driver.

As shown in FIG. 3, the gas (flow rate Q) input to the mass flow controller is divided into a flow rate sensor section 81 (flow rate Q ₁ ) and a bypass section 82 (flow rate Q ₂ ). That is, it is represented by Q = Q ₁ + Q ₂ .

The flow rate sensor section 81 has a resistance wire 84 wound on each of an upstream side and a downstream side of a sensor tube 83, and forms a reference resistance and a bridge circuit 85. The resistance wire 84 also serves as a heater for heating the sensor tube 83, and the bridge circuit 85 is in an equilibrium state when gas is not flowing.

When the gas flows, the heat on the upstream side moves to the downstream side by the gas, the balance is lost, and an output signal 86 is obtained from the bridge circuit 85. In this case, the amount of heat transfer is determined by the mass of the gas. , Gas mass can be measured without being affected by temperature, pressure, etc.

The bypass unit 82 has a structure in which the gas flow ratio between the flow sensor unit 81 and the bypass unit 82 is constant over the entire gas flow measurement range. That is, Q ₁ / Q ₂ = constant.

Thus, the output signal 86 from the sensor is proportional to the actual gas flow. The comparison circuit 87 in the mass flow controller is a setting signal for externally setting the flow rate
The control circuit 89 drives the valve 90 until the difference signal becomes zero, and adjusts the flow path diameter of the variable orifice 91 by comparing the output signal (sensor output) 86 with the output signal (sensor output) 86. To control the gas flow.

[0009]

Therefore, when the flow rate ratio between the flow sensor section 81 and the bypass section 82 is constant, the gas flow rate is controlled at a correct value. However, the purge after opening the gas pipe to the atmosphere is insufficient. Residual moisture in the atmosphere due to
When moisture in the atmosphere due to external leaks enters the gas in the gas flow path, very corrosive products or powdery products are generated, and these products generate a flow rate in the mass flow controller. And the bypass section 82 is corroded or the product is clogged, and the flow rate ratio between the flow sensor section 81 and the bypass section 82 is broken.

In the conventional mass flow controller, even when the above problem occurs, the flow rate recognized by the mass flow controller is the flow rate detected by the flow rate sensor unit 81. Therefore, the flow rate actually input to the mass flow controller is equal to the setting signal. It could not be found even if it deviated from the flow rate set by 88.

The present invention provides a mass flow controller capable of automatically finding the above problem.

[0012]

FIG. 1 is a diagram illustrating the principle of the present invention. In the figure, 1 is a gas passage main body, 11 is a bypass section, 12 is a variable orifice, 2 is a flow sensor section, 21 is a sensor tube, 22 is a resistance wire, 23 is a reference resistance, 3 is a valve drive amount sensor unit, 31 Is a chamber, 32 is a metal diaphragm,
33 is a fixed electrode, 4 is a valve drive unit, 41 is a valve drive shaft,
42 is an electromagnet, 5 is a control unit, 51 is a detection circuit, 52 is a voltage conversion circuit, 53 is a control circuit, and 54 is a storage circuit.

As shown in FIG. 1, a valve driving amount sensor unit 2 for measuring a driving amount of the valve is connected to a valve driving unit 4 for controlling a flow rate in the mass flow controller.

The valve driving amount sensor unit 3 has a diameter of 3
It comprises a thin circular flat metal diaphragm 32 and a fixed electrode 33 fixed to the chamber 31 in opposition thereto.

A valve drive shaft 41 is directly connected to the metal diaphragm 32. When the valve drive shaft 41 moves up and down by the operation of the electromagnet 42, the metal diaphragm 32 bends. The amount of deflection is determined from the change in capacitance between the fixed electrode 33 and the metal diaphragm 32, and the amount of drive of the valve drive shaft 41 is determined.

The change in the capacitance is controlled by the control unit 5.
The change amount is converted into a voltage by the voltage conversion circuit 52 and sent to the control circuit 53. In the control circuit 53, the relationship between the drive amount of the valve drive shaft 41 converted into the voltage and the flow rate detected by the flow rate sensor unit 2 is calibrated and stored in the storage circuit 54 in advance.
It is constantly monitored to see if the initial value of the above relationship is stored.

If a deviation occurs in this relationship, the value is output by an alarm signal or other means. That is,
SUMMARY OF THE INVENTION An object of the present invention is to provide a mass flow controller for controlling a gas flow rate, wherein a gas flow path 1 is provided so as to be openable and closable, and a variable orifice 12 for controlling a gas flow rate.
Means for detecting the degree of opening and closing of the variable orifice 12
A flow rate sensor unit 2 for detecting a gas flow rate of the gas diverted from the gas flow path 1; an opening / closing degree measured by the detection means 3 and 4 and a flow rate value measured by the flow rate sensor unit 2. This is achieved by having a control unit 5 for detecting a correlation.

[0018]

According to the present invention, as described above, the drive amount of the valve drive shaft of the mass flow controller is detected and the correlation with the flow rate detected by the flow rate sensor unit is constantly checked. The collapse of the flow ratio between the flow sensor unit and the bypass unit can be found.

[0019]

FIG. 2 is an explanatory diagram of one embodiment of the present invention. In the figure, 61 is a chamber, 62 is an upper electrode, 63 is a lower electrode, 64 is an RF power supply, 65 is a semiconductor substrate, 66 is a gas pipe, 67
Is a main valve, 68 is a branch valve, 69 is a mass flow controller, 70 is a drive amount sensor unit, 71 is a flow sensor unit, 72 is a control unit, 73 is a gas container, 74
Is a turbo pump and 75 is a dry pump.

FIG. 2 is an explanatory view of the configuration of an embodiment in which the mass flow controller 69 of the present invention is mounted on a semiconductor device manufacturing apparatus for performing dry etching of a thin film deposited on a semiconductor substrate 65.

An RF power supply 64 is connected to an upper electrode 62 and a lower electrode 63 for generating glow discharge plasma in an etching chamber 61. A gas pipe 66 for supplying a reactive gas is connected in the chamber 61,
A plurality of branch valves 68 for selecting a gas to be used for etching from a variety of gases are connected to the end of a main valve 67 that opens and closes a gas flow path connected thereto. Mass flow controllers 69 for adjustment are connected to each other.

The chamber 61 has a turbo pump 74 for evacuating the chamber 61 and a dry pump 75.
Are connected to exhaust the reactive gas. The mass flow controller 69 has a drive amount sensor unit 70 that measures the drive amount of the valve drive shaft, and a control that checks the correlation between the flow rate detected by the flow rate sensor unit 71 and the valve drive amount measured by the drive amount sensor unit 70. Unit 72
Is connected so that the flow rate can be checked automatically.

[0023]

As described above, according to the present invention,
Since it is possible to automatically detect that the flow rate value detected by the sensor is actually a value having an error, a manufacturing trouble caused by a deviation from the actual flow rate is eliminated.

Conventionally, calibration of the mass flow controller has been performed periodically in order to prevent such inconveniences. However, such calibration work is not required, which greatly contributes to improvement of maintenance technology.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory view of one embodiment of the present invention.

FIG. 3 is an explanatory view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas flow path main body 2 Flow rate sensor unit 3 Valve drive amount sensor unit 4 Valve drive unit 5 Control unit 11 Bypass unit 12 Variable orifice 21 Sensor tube 22 Resistance wire 23 Reference resistance 31 Chamber, 32 Metal diaphragm, 33 Fixed electrode 41 Valve drive Axis 42 Electromagnet 51 Detection circuit 52 Voltage conversion circuit 53 Control circuit 54 Storage circuit 61 Chamber 62 Upper electrode 63 Lower electrode 64 RF power supply 65 Semiconductor substrate 66 Gas piping 67 Main valve 68 Branch valve 69 Mass flow controller 70 Driving amount sensor unit 71 Flow rate sensor Part 72 Control unit 73 Gas container 74 Turbo pump 75 Dry pump

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-69874 (JP, A) JP-A-63-48422 (JP, A) JP-A-62-100817 (JP, A) 107407 (JP, A) JP-A-3-156509 (JP, A) JP-A-57-187715 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G05D 7/06 G01F 1 / 68

Claims (3)

(57) [Claims] In a mass flow controller for controlling a gas flow rate, a variable orifice (1) is provided so as to open and close a gas flow path, and controls a gas flow rate.
2) and means for detecting the opening / closing degree of the variable orifice (12)
(3, 4), a flow sensor unit (2) for detecting the gas flow rate of the gas diverted from the gas flow path (1), and the detection means (3,
A mass flow controller comprising a control unit (5) for detecting a correlation between the opening / closing degree measured in (4) and the flow rate value measured in the flow rate sensor section (2). 2. A gas flow path main body of a mass flow controller.
The gas flowing into (1) passes through the bypass section (11) and the flow sensor section.
(2) at a fixed ratio, merges again, passes through a variable orifice (12), and is sent out.The flow rate sensor section (2) includes a sensor tube (21), and the sensor tube. And heating means (22, 23) provided in (21) for extracting the collapse of thermal equilibrium due to the passage of gas as an output signal proportional to the gas flow rate, and the detecting means (3, 4) comprises: It comprises a cylindrical chamber (31), a metal diaphragm (32) and a fixed electrode (33). The metal diaphragm (32) is placed in the cylindrical chamber (31).
A valve drive amount sensor unit (3) provided with a fixed electrode (33) opposed to the metal diaphragm (32) and fixed to the chamber (31); and a valve drive directly connected to the metal diaphragm (32). axis
A valve drive unit (4) for controlling the variable orifice (12) by driving the fixed electrode (33) by bending the metal diaphragm (32) by driving the valve drive shaft (41). ) And the metal diaphragm (32) to change the capacitance,
The control unit (5) has a detection circuit (51) and a control circuit (53), and detects the change in the capacitance by using the detection circuit (51).
The control circuit (53) detects the output of the detection circuit (51),
2. The mass flow controller according to claim 1, wherein a relationship with an output of said flow rate sensor section is detected. 3. An apparatus for manufacturing a semiconductor device, wherein a gas flow rate is controlled using the mass flow controller according to claim 1.