This invention relates to a flow rate ratio controlling apparatus that divides a precursory gas used for a semiconductor manufacturing process at a desired ratio.
Nowadays in a field of a semiconductor manufacturing process, a process chamber to house a wafer is also upsized because the wafer is upsized. In case of film forming the semiconductor wafer, it is preferable that a precursory gas for film forming is even. However, if the precursory gas is introduced to the upsized process chamber from one position alone, there might be a case that a concentration distribution becomes uneven.
Recently, a plurality of gas inlets are provided for the process chamber and from each of the gas inlets fed is the precursory gas whose mass flow rate ratio is controlled so that a gas concentration in the process chamber becomes even. At this time, as an apparatus to divide the precursory gas at a desired ratio, a flow rate ratio controlling apparatus is used.
Conventionally, as this kind of the flow rate ratio controlling apparatus, a method for dividing the precursory gas by the use of the pressure in each pipe is general. However, since this method does not directly control the ratio of the mass flow rate, an actual ratio of the mass flow rate is unclear.
Then as shown in the patent document 1 devised is a flow rate ratio controlling apparatus that conducts ratio control by measuring the mass flow rate.
Patent document 1: Japan patent laid-open number 2005-38239
However, this type of the flow rate ratio controlling apparatus requires two types of devices such as a flow rate controller and a pressure controller.
In consideration of these problems, a main object of this invention is to provide a flow rate ratio controlling apparatus that does not require multiple types of devices so as to enable reduction of a number of types of component and a manufacturing cost.
In order to solve these problems the preset claimed invention takes the following measures.
More specifically, the flow rate ratio controlling apparatus of this invention comprises a differential pressure flow rate controller wherein a flow rate control valve to control a flow rate of a fluid flowing in an internal flow channel, a first pressure sensor, a fluid resistance, and a second pressure sensor are arranged serially in this order in the internal flow channel and that can measure the flow rate of the fluid based on the detected pressures detected by the first pressure sensor and the second pressure sensor, and a control processing mechanism that is arranged in the internal flow channel to give commands to the differential pressure flow rate controller to control it, and is characterized by that the differential pressure flow rate controller is arranged respectively in each of the multiple branched flow channels branched from a terminal of a main flow channel, for the flow rate controller arranged in one branched flow channel, the second pressure sensor is arranged to locate at an upstream side of the flow rate control valve, the first pressure sensor and the fluid resistance, and the flow rate controller is operated so that a detected pressure detected by the second pressure sensor achieves a previously determined target pressure, for the differential pressure flow rate controller arranged in the other branched flow channel, the flow rate control valve is arranged to locate at an upstream side of the first pressure sensor, the fluid resistance and the second pressure sensor, and a target flow rate to be flown in the differential pressure flow rate controller arranged in the other branched flow channel is calculated by the control processing mechanism based on a total measured flow rate output from all of the differential pressure flow rate controllers and a previously determined flow rate ratio, and the differential pressure flow rate controller is operated so as to achieve the target flow rate.
In accordance with this arrangement, since the identical type of the differential pressure flow rate controller is used for one branched flow channel and the other branched flow channel and the differential pressure flow rate controller arranged in one branched flow channel is operated so as to be the previously determined target pressure for one branched flow channel while the differential pressure flow rate controller arranged in the other branched flow channel is operated so as to be the target flow rate for the other branched flow channel, it is possible to control the mass flow rate ratio of the fluid flowing in each branched flow channel.
Furthermore, since only the identical type of the differential pressure flow rate controller is used, it is possible to reduce a type of the component constituting the flow rate ratio controlling apparatus, thereby reducing the manufacturing cost.
In addition, since only the differential pressure flow rate controller is used, it is possible to control the flow rate ratio of the fluid flowing in each branched flow channel more accurately on a constant basis compared with a case that the thermal mass flow meter is used even though a pressure change of the fluid flowing into the flow rate ratio controlling apparatus is big. Furthermore, since only the differential pressure flow rate controller is used, it is also possible to control the mass flow rate ratio with high accuracy even though an inlet side of the differential pressure flow rate controller and an outlet side thereof are at a negative pressure.
As another embodiment of the flow rate ratio controlling apparatus that can control the mass flow rate ratio of a fluid flowing in each branched flow channel with reducing a number of types of components together with high accuracy by using only the differential pressure flow rate controller of the identical type is used represented is a flow rate ratio controlling apparatus comprising a differential pressure flow rate controller wherein a first step pressure sensor, a flow rate control valve to control a flow rate of a fluid flowing in an internal flow channel, a first pressure sensor, a fluid resistance, and a second pressure sensor are arranged serially in this order in the internal flow channel and that can measure the flow rate of the fluid based on the detected pressures detected by the first pressure sensor and the second pressure sensor, and a control processing mechanism that is arranged in the internal flow channel to give commands to the differential pressure flow rate controller to control it and that is arranged in the internal flow channel, wherein the differential pressure flow rate controller is arranged respectively in each of the multiple branched flow channels branched from a terminal of a main flow channel, for the flow rate controller arranged in one branched flow channel, the differential pressure flow rate controller is operated so that a detected pressure detected by the first step pressure sensor achieves a previously determined target pressure, for the differential pressure flow rate controller arranged in the other branched flow channel, a target flow rate to be flown in the differential pressure flow rate controller arranged in the other branched flow channel is calculated by the control processing mechanism based on a total measured flow rate output from all of the differential pressure flow rate controllers and a previously determined flow rate ratio, and the differential pressure flow rate controller is operated so as to achieve the target flow rate.
In accordance with this invention having the above-mentioned arrangement, it is possible to control the mass flow rate ratio of the fluid flowing in each branched flow channel with high accuracy together with reducing a manufacturing cost by reducing a number of a type of the components because only the same type of the component is used.
A first embodiment of this invention will be explained with reference to drawings.
As shown in
As shown in
The control processing mechanism C comprises at least a CPU, a memory and various driver circuits as hardware and produces various functions in cooperation with the CPU and its peripheral devices according to a program stored in the memory.
Next, an operation of the flow rate ratio controlling apparatus 100 will be explained. For convenience of explanation, two mass flow controllers MSC1 and MSC2 are described separately as the first mass flow controller MFC1 and the second mass flow controller MFC2, however, the mass flow controllers MSC1 and MSC2 are of the completely identical mass flow controller.
For the first mass flow controller MFC1 wherein the second pressure sensor P21 is arranged in the upstream side, the control processing mechanism C conducts feedback-control on the flow rate control valve V1 of the first mass flow controller MFC1 by the use of the deviation between the pressure detected by the second pressure sensor P21 and a target pressure stored in the memory. In addition, the control processing mechanism C calculates the mass flow rate flowing in the internal flow channel L1 of the first mass flow controller MFC1 based on the pressure difference generated in the fluid resistance R1 detected by the second pressure sensor P21 and the first pressure sensor P11.
For the second mass flow controller MFC2 wherein the flow rate control valve V2 is arranged in the upstream side, the control processing mechanism C calculates the mass flow rate flowing in the internal flow channel L2 of the second mass flow controller MFC2 based on the pressure difference generated in the fluid resistance R2 detected by the first pressure sensor P12 and the second pressure sensor P22. Then the control processing mechanism C calculates a target mass flow rate to be flown in the second mass flow controller MFC2 based on the mass flow rate of the fluid flowing in each branched flow channel BL1, BL2 and a target flow rate ratio of each branch flow channel BL1, BL2 stored in the memory. The control processing mechanism C conducts feedback-control on the flow rate control valve V2 of the second mass flow controller MFC2 by the use of the deviation between the mass flow rate flowing in the internal flow channel L2 of the second mass flow controller MFC2 and the target mass flow rate.
In accordance with this arrangement, it is possible both to constitute the flow rate ratio controlling apparatus 100 using only the identical mass flow controller MFC1, MFC2, thereby reducing a manufacturing cost by reducing a number of a type of the components and also to control the flow rate ratio with high accuracy.
Furthermore, it is possible to control the flow rate ratio just with a very simple change of the mounting method such that one of the mass flow controllers MFC1, MFC2 is mounted in an opposite direction to an ordinary direction.
In addition, since the measurement of the mass flow rate is conducted by means of only the differential pressure type, even though a pressure change of the fluid flowing into the mass flow controller MFC1, MFC2 is big, it is possible to control the flow rate ratio with accuracy on a constant basis compared with a case of using a thermal type mass flow rate measurement method.
Next, a second embodiment of this invention will be explained with reference to
As shown in
As shown in
Next, an operation of the flow rate ratio controlling apparatus 100 will be explained. For convenience of explanation, two mass flow controllers MSC1 and MSC2 are described separately as the first mass flow controller MFC1 and the second mass flow controller MFC2, however, the mass flow controllers MSC1 and MSC2 are of the completely identical mass flow controller.
For the first mass flow controller MFC1, the control processing mechanism C conducts feedback-control on the flow rate control valve V1 of the first mass flow controller MFC1 by the use of the deviation between the pressure detected by the first step pressure sensor P01 and a target pressure stored in the memory. In addition, the control processing mechanism C calculates the mass flow rate flowing in the internal flow channel L1 of the first mass flow controller MFC1 based on the pressure difference generated in the fluid resistance R1 detected by the first pressure sensor P11 and the second pressure sensor P21.
For the second mass flow controller MFC2, the control processing mechanism C calculates the mass flow rate flowing in the internal flow channel L2 of the second mass flow controller MFC2 based on the pressure difference generated in the fluid resistance R2 detected by the first pressure sensor P12 and the second pressure sensor P22. Then the control processing mechanism C calculates a target mass flow rate to be flown in the second mass flow controller MFC2 based on the mass flow rate of the fluid flowing in each branched flow channel BL1, BL2 and a target flow rate ratio of each branched flow channel BL1, BL2 stored in the memory. The control processing mechanism C conducts feedback-control on the flow rate control valve V2 of the second mass flow controller MFC2 by the use of the deviation between the mass flow rate flowing in the internal flow channel L2 of the second mass flow controller MFC2 and the target mass flow rate.
In accordance with this arrangement, it is possible to control the mass flow rate ratio of each branched flow channel BL1, BL2 with high accuracy together with reducing a manufacturing cost by reducing a number of a type of the components. In addition, in case of this second embodiment, it is also possible to omit a process of changing the direction of the mass flow controllers MFC1, MFC2 and it is possible to arrange the identical mass flow controller MFC1, MFC2 in all of the flow channels.
In addition, since the measurement of the mass flow rate is conducted by means of only the differential pressure type, even though a pressure change of the fluid flowing into the mass flow controller MFC1, MFC2 is big, it is possible to control the flow rate ratio with accuracy on a constant basis.
The present claimed invention is not limited to the above-mentioned embodiment.
For example, a number of the branched flow channel is two, however, a further more number of flow channels may be provided. In this case, at least one of the mass flow controllers as being the flow rate controller arranged in each branched flow channel may control the pressure as a reference.
In the above-mentioned embodiment, one control processing mechanism is provided for all of the flow rate controllers, however, the control processing mechanism may be arranged for each flow rate controllers and each control processing mechanism may control the flow rate ratio cooperatively each other.
Furthermore, the present claimed invention can be applied not only to the semiconductor manufacturing process but also to other gas and a liquid, and in case it is applied to the gas and the liquid, the same action and effect can be produced as that of the above-mentioned embodiment.
In addition, the present claimed invention may be variously modified without departing from a spirit of the invention.
In accordance with this invention, it is possible for the flow rate ratio controlling apparatus both to reduce a number of a type of components so as to reduce a manufacturing cost and to control the mass flow ratio of the fluid flowing in each branched flow channel with high accuracy.
Number | Date | Country | Kind |
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2007-338257 | Dec 2007 | JP | national |
Number | Date | Country | |
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Parent | 12809836 | Jun 2010 | US |
Child | 13348745 | US |