JPH08153681A - Vacuum processing chamber pressure control method of semiconductor manufacture device and its device - Google Patents

Abstract

PURPOSE: To enable pressure control of an interior of a vacuum processing chamber to a required pressure in a short time in vacuum processing chamber pressure control of a semiconductor manufacturing device and to prevent gas mixture rate after pressure control from varying to process conditions. CONSTITUTION: In a semiconductor manufacturing device with a plurality of gas lines 2, 3, 4 communicated to a vacuum processing chamber 1, gas flow rate controllers 5, 7, 9 are provided to the gas lines, allowance of a full scale to process conditions set flow rate of each flow rate controller is obtained and a flow rate multiplied by process conditions set flow rate in each gas line is obtained by making allowance of a gas line of minimum allowance a constant. The obtained gas flow rate is a maximum flow rate of flowable gas without changing gas mixing rate in a range not exceeding a full scale of each flow rate controller. Pressure of a vacuum processing chamber is controlled by controlling gas flow rate in the range of the maximum flow rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure control method and apparatus for a vacuum processing chamber of a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art A vacuum processing chamber of a semiconductor manufacturing apparatus and a conventional vacuum processing chamber pressure control method will be briefly described with reference to FIG.

The vacuum processing chamber 1 has a first gas supply line 2,
The second gas supply line 3 and the third gas supply line 4 communicate with each other, and each line has a first flow rate controller 5, an air valve 6, a second flow rate controller 7, an air valve 8, a third flow rate controller 9, and an air valve 10. Are provided respectively. An exhaust line 12 is connected to the vacuum processing chamber 1 via a gate valve 11, and a variable conductance valve 13 and a vacuum pump 14 are provided in the exhaust line 12 from the vacuum processing chamber 1 side.

In order to increase the process pressure in the vacuum processing chamber 1 by the reaction gas, first, the air valves 6, 8 and 10 are closed, and the gate valve 11 is closed.
Is opened and the vacuum pump 14 evacuates. When the inside of the vacuum processing chamber 1 reaches a predetermined degree of vacuum, the air valve 6, the air valve 8, and the air valve 10 are opened, and the first gas supply line 2, the second gas supply line 3, and the third gas supply line 3 are connected to the vacuum processing chamber 1. Gas is supplied from the gas supply line 4 through the first flow rate controller 5, the second flow rate controller 7, and the third flow rate controller 9. The first flow rate controller 5, the second flow rate controller 7, and the third flow rate controller 9 set the gas flow rate of each line so that the gas flow rate and the gas mixing ratio at the time of the process can be obtained.

When the pressure is increased to near the process pressure, the gate valve 11 is opened, the opening of the variable conductance valve 13 is controlled while the pressure detected by the pressure sensor 18 is monitored, and the exhaust speed is adjusted to adjust the process pressure.

[0006]

The gas supply flow rate under normal vacuum processing chamber process conditions is smaller than the volume of the vacuum processing chamber, and it takes a lot of time for the vacuum processing chamber to reach the process pressure from the vacuum state. It costs. Also, if an excessive gas flow rate is supplied at the time of pressure adjustment, particles in the vacuum processing chamber will be rolled up and contamination of the object to be processed will be induced. Furthermore, if the gas flow rate is increased without considering the gas mixture ratio, it will take a long time for the gas mixture ratio after pressure adjustment to meet the conditions required for processing, and there will be a slight difference in the gas mixture ratio. There is a problem that the quality of the processed material is not constant.

In view of the above situation, the present invention can adjust the pressure in the vacuum processing chamber to a required pressure in a short time, and the gas mixing ratio after the pressure adjustment does not change with the process conditions. Is.

[0008]

SUMMARY OF THE INVENTION The present invention is a semiconductor manufacturing apparatus having a plurality of gas lines communicating with a vacuum processing chamber, wherein each of the gas lines is provided with a flow rate controller,
The full-scale margin with respect to the process condition set flow rate of each of the flow rate regulators is obtained, and the flow rate multiplied by the process condition set flow rate in each gas line is obtained with the margin of the gas line having the smallest margin as a constant. The gas flow rate thus obtained is supplied as a maximum flow rate to the vacuum processing chamber to adjust the pressure.

[0009]

[Operation] By multiplying the set flow rates of the flow rate regulators of all the gas lines to be used by the margin, the maximum flow rate that can flow without changing the gas mixing ratio within the full scale of each flow rate regulator is obtained. The flow rate is increased or decreased while maintaining the gas mixture ratio of the process condition within this maximum flow rate range.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the same parts as those shown in FIG. 3 are designated by the same reference numerals, and 15 is a controller and 16
Is an external input device connected to the controller 15, and 17 is a storage device provided in the controller 15 to which a pressure control program is set and input. The first flow rate controller 5 and the second flow rate controller 7 are shown. The third flow rate controller 9 is designed to set the flow rate in response to a command from the controller 15.

From the external input device 16, a gas mixing ratio that matches the process conditions is set. Generally, the actual flow rate is sufficiently small with respect to the full scale of the flow rate controller. Therefore, the flow regulator has the ability to control more flow than the gas flow at process conditions. From this, as a preparation for starting the pressure regulating operation, it is calculated how much the flow rate can be increased without changing the mixing ratio of the process conditions.

The full scale of the first flow rate controller 5 is set to F
₁ , the full scale of the second flow controller 7 is F ₂ , the full scale of the third flow controller 9 is F _3, and the first flow controller 5 is
Let V _{1 be} the process set flow rate of the second flow controller, V _{2 be} the process set flow rate of the second flow rate controller 7, and V ₃ be the process set flow rate of the third flow rate controller 9, and calculate the margin state for the set flow rate of each flow rate controller. .

That is, V _n / F _n is calculated for each flow rate controller, and the maximum value M of V _n / F _{n is} further calculated. V _n / F _n
The flow rate controller having the maximum value M of is a flow rate controller that sets the flow rate that is closest to the full scale, and has the least margin with respect to the process set flow rate. Next, the margin F _n / V _n (1 / M) = C is obtained for the flow rate controller.

The set flow rates V ₁ and V of the first flow rate controller 5, the second flow rate controller 7, and the third flow rate controller 9 are set.
_{2. The} flow rate obtained by multiplying the set flow rate V ₃ by C is the maximum value at which the gas flow rate can be increased without exceeding the full scale of each flow rate controller without changing the gas mixture ratio of the processing conditions.

As described above, when a large flow rate is suddenly supplied to the vacuum processing chamber 1, the particles in the vacuum processing chamber 1 are rolled up to induce contamination of the object to be processed. Therefore, the flow rate is gradually increased at the beginning of inflow and gradually decreased at the end of inflow. It goes without saying that the gas mixing ratio is kept constant even when the flow rate is decreased or increased, and the flow rate control of each flow rate controller is based on the flow rate obtained by multiplying the set flow rate of the process condition by the same constant. I do.

Thus, the lamp U having a predetermined flow rate in each line
The ramp rate of each flow rate controller is calculated so that the flow rate will be the set flow rate in P hours, and the set flow rate of all flow rate controllers is set to 0 at the start of gas supply, and the set flow rate of the flow rate controllers is increased with time to adjust the flow rate. Before the pressure ends, the gas flow rate is reduced to the set flow rate in the process conditions.

The pressure control program is FS (Ful
l Scale) conversion routine, gas flow rate calculation routine, and gas flow rate control routine.

First, the FS conversion routine will be described.

In this routine, the set flow rate of one gas flow rate controller and the full-scale flow rate of the flow rate controller are given as a 16-bit binary number, and the set flow rate corresponds to what percentage of the full-scale flow rate. Is calculated, and the calculation result is (for example, this time) 0000 (Hex) to 07FF (Hex)
It is converted to binary number and output.

The calculation formula is shown below. However, division is processed by double-precision arithmetic. If this method is used for calculation, there will be no missing digits or overflow. [Calculation result] (Hex) = ([Flow rate controller set flow rate of gas]
(Hex) x [07FF] (Hex)) / [Full-scale flow rate of flow controller used] (Hex)

Next, the gas flow rate calculation routine will be described.

This routine obtains the maximum flow rate of each gas that can be flowed without changing the mixing ratio of the mixed gas flow rates from the converted values of each gas output in the "FS conversion routine". The maximum value of the FS conversion value in the gas used is determined. The maximum value of [07FF] (Hex) / FS conversion value = C is obtained. The set flow rate at the time of pressure regulation is obtained by multiplying the set flow rate by the count C obtained in.

Since the FS converted value indicates what percentage of the full scale of the flow controller the set flow rate of the flow controller corresponds to, the maximum value of the FS converted value in the gas used is calculated, When calculating the ratio with the maximum value of conversion [07FF] (Hex), the flow rate of the flow rate controller (flow rate controller with the maximum FS conversion value) that sets the flow rate closest to full scale is set to full scale flow rate. , A margin constant can be obtained by multiplying the current set value.

By multiplying the set flow rate of the flow rate controller for each of all the gas types used by the above constant, it is possible to flow without changing the gas mixing ratio within the range not exceeding the full scale of the flow rate controller of each of the all gas types used. Maximum flow rate will be obtained.

Next, the gas flow rate control routine will be described.

This routine is a routine for actually outputting the gas flow rate to the flow rate controller based on the gas set flow rate obtained by the "FS conversion routine" and the "gas flow rate calculation routine".

As described above, if the gas flow rate calculated by the gas flow rate calculation routine is set at the start of gas supply, a large amount of gas flows at once, which may cause particles to be wound up in the vacuum chamber. The ramp controller set ramp rate is calculated so as to reach the preset flow rate during the ramp-up time, the total gas preset flow rate is set to 0 sccm at the start of gas supply, and the preset flow rate of the flow controller is changed with time. Further, the gas flow rate is reduced to a normal process gas flow rate before the pressure adjustment is completed.

FIG. 2 shows changes in the set gas flow rate and the pressure in the processing chamber in the above sequence.

In the above embodiment, 3 gas lines have been described, but it goes without saying that the same operation can be carried out even if there are 2 or 4 or more gas lines.

[0031]

As described above, according to the present invention, the following excellent effects are exhibited.

It is possible to supply a large amount of process gas at the time of pressure regulation and shorten the time required to reach the process pressure from the high vacuum.

Since the gas having the same gas mixture ratio as the normal process gas is supplied during the pressure adjustment, it is possible to obtain the desired process result because the gas composition is different at the start of the process.

Since the gas flow rate is ramped up when the gas is supplied, it is possible to suppress the particles from being wound up.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an apparatus for implementing the present invention.

2A, 2B and 2C are graphs showing a gas flow rate control state of each line, and FIG. 2D is a graph showing a pressure state of a vacuum processing chamber.

FIG. 3 is an explanatory diagram showing an outline of a semiconductor manufacturing apparatus.

[Explanation of symbols]

 5 1st flow controller 7 2nd flow controller 9 3rd flow controller 13 Variable conductance valve 15 Controller 16 External input device 17 Memory device 18 Pressure sensor

Claims (3)

[Claims] 1. A semiconductor manufacturing apparatus having a plurality of gas lines communicating with a vacuum processing chamber, wherein each gas line is provided with a flow rate controller, and a full scale for a process condition set flow rate of each of the flow rate controllers. The margin is calculated, the margin of the gas line with the smallest margin is used as a constant, and the flow rate is multiplied by the process condition setting flow rate in each gas line. The obtained gas flow rate is used as the maximum flow rate in the vacuum processing chamber. A method for controlling a pressure in a vacuum processing chamber of a semiconductor manufacturing apparatus, comprising: 2. The method of controlling the pressure in a vacuum processing chamber of a semiconductor manufacturing apparatus according to claim 1, wherein the gas flow rate is increased or decreased while maintaining the gas mixture ratio of the process conditions. 3. A plurality of gas lines communicating with the vacuum processing chamber, flow rate controllers provided in the respective gas lines, and a margin of process condition setting flow rate with respect to full scale of each flow rate controller are obtained. , A control for controlling the flow rate regulator by using the margin of the gas line with the smallest margin as a constant to obtain a flow rate multiplied by the process condition setting flow rate in each gas line, and using the obtained gas flow rate as the maximum flow rate. And a vacuum processing chamber pressure control apparatus for a semiconductor manufacturing apparatus.