JPH06259144A - High-speed pressure control method - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a high-speed pressure control method capable of solving the increase in pressure adjustment time accompanying an increase in chamber volume and shortening the pressure adjustment time regardless of the chamber volume. [Structure] A chamber 1 for controlling pressure and a mass flow controller 4 for introducing a gas 5 into the chamber 1.
A turbo molecular pump 3 for sucking the gas 5 in the chamber 1 through the variable conductance valve 2, a main controller 8 for controlling the mass flow controller 4, and the variable conductance valve for receiving the pressure in the chamber 1. 2 and an automatic control unit 7 that controls the main control unit 8. When the automatic control unit 7 introduces a gas into the chamber 1 that has been evacuated to a high vacuum, the pressure in the chamber 1 reaches a set pressure P. The gas flow rate is controlled so as to flow in a larger amount than the original set flow rate Q at a constant primary flow rate Q ₁ due to a high primary set value, and to reach the secondary set flow rate Q at the same time when the set pressure P is reached next time. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high speed pressure control method, and more particularly to a pressure control method for achieving high speed pressure control in a pressure control system of a vacuum apparatus for wafer processing in a semiconductor manufacturing apparatus. .

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing apparatus, a wafer is placed in a vacuum, and various kinds of reaction gases are brought into contact with each other to cause a physicochemical reaction to form an integrated circuit. Thus, FIG.
As shown in FIG. 3, the chamber 1 which is a vacuum chamber is sucked by the turbo molecular pump 3 through the variable conductance valve 2 to a high vacuum, and then the chamber 1 evacuated to this high vacuum is passed through the mass flow controller 4 to a constant flow rate. Gas 5 was introduced to adjust the gas pressure to the set pressure. At the start of introducing the gas, the variable conductance valve 2 of the exhaust system is almost fully closed.

Next, the diaphragm gauge 6 is attached to the chamber 1.
The automatic control unit 7 sends a signal to the main control unit 8 in response to the detected vacuum pressure in the chamber 1, the main control unit 8 opens the mass flow controller 4, and the gas 5 is supplied into the chamber 1 at the normal set flow rate Q. (Step a _{1 in} FIG. 4). Thus, immediately after the gas pressure in the chamber 1 reaches the set pressure P as shown in step a ₂ of FIG.
Adjusts the opening degree of the variable conductance valve 2 to maintain the pressure inside the chamber 1 at the set pressure as shown in step a ₃ . After that, it stabilizes at the set pressure as shown in step a ₄ . Therefore, the pressure in the chamber 1 changes as shown by the curve α in the graph of FIG. 5, the flow rate of the gas 5 changes as shown by the curve β, and the flow rate is maintained at the set flow rate in step a ₄ . The horizontal axis of the graph represents time t, and the vertical axis represents pressure and flow rate.

However, the mass flow controller 4 rises to the set flow rate at the start of gas introduction due to its hardware characteristics, but at least 2-3 regardless of the size of the set flow rate.
It takes seconds. Further, when the volume of the chamber 1 is large and the set flow rate of the mass flow controller is small, the time until the gas pressure in the chamber 1 rises to the set pressure T ₁ becomes long, so the time until the set pressure stabilizes, that is, the adjustment The pressure time t ₁ also increases. At present, the level of research-level semiconductor manufacturing equipment has shifted from the batch type to the single-wafer type, and with the batch type, the pressure adjustment time required for the whole is very small when converted to one sheet All such pressure adjustment times are integrated and become a large amount.

[0005]

However, in the pressure adjusting time t ₁ in the conventional pressure control method, the specific gravity is larger than the process time which is shortened year by year, and the efficiency is lowered. Further, as the volume of the chamber 1 increases, the gas flow rate during the process does not flow in a large amount in proportion to the volume of the chamber, so that a small gas flow rate must occupy a large chamber volume. Since the rate of increase of the gas pressure decreases as the chamber volume increases, the time T ₁ until the gas pressure reaches the set pressure is extended, and the pressure adjusting time t _{1 of the} gas pressure in the chamber ₁ is further lengthened. .

The object of the present invention is to solve the problem of the prior art, that is, the increase in pressure adjustment time accompanying the increase in chamber volume,
An object of the present invention is to provide a high-speed pressure control method capable of shortening the pressure adjustment time without being affected by the chamber volume.

[0007]

The present invention has been made in view of the above problems, and includes a chamber 1 for controlling pressure,
A mass flow controller 4 that introduces a gas 5 into the chamber 1, a turbo molecular pump 3 that sucks the gas 5 inside the chamber 1 through a variable conductance valve 2, and a main controller 8 that controls the mass flow controller 4. The automatic control unit 7 controls the variable conductance valve 2 and the main controller 8 by receiving the pressure in the chamber 1.

[0008]

When the gas is introduced into the chamber 1 that is evacuated to a high vacuum, the automatic control unit 7 keeps the gas flow rate constant until the pressure in the chamber 1 reaches the set pressure P by a constant high flow rate Q ₁ At the same time, a larger amount than the original set flow rate Q is flown in, and at the same time when the set pressure P is reached next, the secondary set flow rate Q is controlled to be the original set flow rate Q. It should be noted that although this large amount of gas having a constant flow rate Q ₁ is made to flow by the primary control, this “large amount” is not set to a level of tens of times the original set flow rate and is not accompanied by danger.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIGS. Gas is introduced into the chamber 1 evacuated to a high vacuum through the mass flow controller 4 at a set flow rate Q ₁ of a primary high set value. As shown in step b ₁ of FIG. 1, this primary flow rate Q ₁ is determined by the set pressure P in the chamber 1, the time T _{2 at} which the gas pressure in the chamber 1 reaches the set pressure, the capacity of the chamber 1, the exhaust amount, etc. But
In order to suppress the amount of overshoot after the set pressure P is exceeded, it is determined in consideration of the time T ₂ . As a result, the gas pressure in the chamber 1 rapidly approaches the set pressure P as indicated by the curve α ₁ of the graph 2 in FIG.

Thus, when the gas pressure in the chamber 1 reaches the set pressure P as shown in step b ₂ , the automatic control unit 7 adjusts the opening degree of the variable conductance valve 2 to show the variable conductance valve 2 as shown in step b _3.
Is returned to the secondary set flow rate Q of the original set value, the automatic pressure control by the automatic control unit 7 is started, the gas pressure in the chamber 1 is controlled, and the time is stabilized at the set pressure, that is, the pressure adjustment time. At t ₂ , the set pressure becomes P as shown in step b ₄ , and the set pressure P is stabilized as shown in step b ₅ .

As described above, in the high-speed pressure control method according to the present invention, the gas pressure in the chamber 1 changes as shown by the curve α of the graph 2 in FIG. 2, and the flow rate of the gas 5 is the curve β.
It changes as shown in ₁ .

[0012]

As described above, according to the present invention, when the gas is introduced into the chamber 1 which is evacuated to a high vacuum, the flow rate of the gas is increased to the first order until the pressure in the chamber 1 reaches the set pressure P. At a constant flow rate Q ₁ according to the set value, a larger amount than the original set flow rate Q is poured, and at the same time when the set pressure P is reached, the secondary set flow rate Q is set to the original secondary set flow rate Q. Since the exceeded time T ₂ is shortened, the time for stabilizing the set pressure P, that is, the pressure adjusting time t ₂ is also shortened. Therefore, the pressure adjusting time t ₁ at the time of introducing the gas can be shortened, so that the efficiency is improved, and by increasing the first-order high set value, it is possible to deal with a large chamber volume at high speed.

[Brief description of drawings]

FIG. 1 is a flow chart of the present invention.

FIG. 2 is a graph showing the relationship between time and pressure.

FIG. 3 is a block diagram of a conventional device.

FIG. 4 is a flowchart thereof.

FIG. 5 is a graph showing the relationship between time and pressure.

[Explanation of symbols]

1 chamber 2 variable conductance valve 3 turbo molecular pump 4 mass flow controller 5 gas 7 automatic control unit 8 main control unit P set pressure Q ₁ constant flow rate Q set flow rate

Claims (1)

[Claims] 1. A chamber for controlling pressure, a mass flow controller for introducing gas into the chamber,
A turbo molecular pump that sucks gas in the chamber through a variable conductance valve, a main control unit that controls the mass flow controller, and an automatic control that controls the variable conductance valve and the main control unit by receiving the pressure in the chamber. When the gas is introduced into the chamber that is evacuated to a high vacuum, the automatic control unit consists of a unit and the gas flow rate is originally set at a constant flow rate by the primary high set value until the pressure inside the chamber reaches the set pressure. A high-speed pressure control method characterized by pouring a larger amount than the flow rate, and then controlling so that the secondary set flow rate is reached at the same time when the set pressure is reached next.