JP5773360B2 - Flow measuring device - Google Patents

Description

  The present invention relates to a flow rate measuring device for measuring the flow rate of a gas flowing in a pore, and more specifically, a pore serving as a gas injection port of a shower plate for introducing a raw material gas into a reaction chamber under reduced pressure by a CVD device. The present invention relates to one used for measuring the flow rate of flowing gas.

  A semiconductor device manufacturing process includes, for example, a film forming process, and a CVD method is one of film forming methods used in this film forming process. A CVD apparatus that performs a CVD method includes a vacuum chamber that defines a reaction chamber, and an exhaust pipe that is connected to a vacuum pump and is provided with a pressure control valve or the like is connected to the vacuum chamber. Further, a gas gas introduction part for a source gas is provided inside the top plate of the vacuum chamber, and a stage for positioning and holding a substrate to be processed is provided at the bottom part of the vacuum chamber so as to face the gas introduction part ( For example, see Patent Document 1).

  For example, the gas introduction part has the same form (the same as a predetermined pattern on a plate-like member mounted on the annular wall standing on the inner side of the vacuum chamber and the lower surface of the annular wall. And a shower plate having a plurality of pores of the same diameter and the same length), and the space defined by the annular wall and the shower plate is premixed or at least two types without mixing. A gas introduction pipe for introducing the raw material gas at a constant flow rate is connected. Then, the source gas introduced into the space is once diffused in the space and supplied to the substrate surface in the processing chamber through each pore of the shower plate.

  Here, as one of the methods for improving the uniformity of the film thickness in the substrate surface when the film is formed by the CVD method, the gas flow rate of the source gas supplied to the substrate through each pore of the shower plate is set. It can be considered to be uniform, and this requires that there is no variation in the processing accuracy of each pore of the shower plate, in other words, the conductance of each pore needs to match each other. Conventionally, the variation in the processing accuracy of the pores formed in the shower plate in this way has been managed by, for example, inserting a pin gauge into each pore.

  However, in recent years, in order to further improve the uniformity of the film thickness distribution, for example, a high aspect ratio having a diameter of 1 mm and a hole length of 20 mm or more is used as each pore formed in the plate-like member. In some cases. In such a case, depending on the material of the base material of the shower plate, it may be difficult to accurately machine all of the pores in the base material. For this reason, the conventional management method using a pin gauge not only has poor workability, but also cannot substantially determine whether the conductances of the respective pores coincide with each other. However, it is desired to develop an apparatus for measuring the conductance efficiently and accurately, that is, for measuring the flow rate of gas flowing in the pores.

JP 2005-158919 A

  In view of the above points, the present invention provides a flow rate measuring apparatus with good workability capable of measuring the flow rate of a gas flowing through the pores efficiently and accurately even for pores with a high aspect ratio. Is the issue.

  In order to solve the above-described problems, the present invention provides a flow rate measuring device for measuring a flow rate of a gas flowing in a pore formed in a member having a predetermined shape as a measurement object, and measuring the flow rate of the gas from the atmospheric pressure. A suction means for sucking at a low predetermined pressure, and a main intake passage and a comparison intake passage connected to the suction means respectively, the main intake passage is detachably connected to one side of the pore, and the comparison intake passage is narrow. A second measurement reference hole corresponding to the pore is provided in the comparative intake passage, and a third measurement reference corresponding to the pore is provided in the main intake passage. A hole is interposed, and the suction means is operated to suck the gas through the fine hole and the first measurement reference hole, respectively, and between the fine hole and the third measurement reference hole and both the first and second measurement holes. A first measurement for measuring a pressure difference between the main intake passage and the comparative intake passage between the measurement reference holes Characterized in that a stage.

  According to the present invention, after one end of the main intake passage is connected to one side of the pore, the suction means is operated, and the main intake passage and the comparison intake passage are sucked by the suction means at a predetermined pressure lower than the atmospheric pressure, respectively. Then, gas (for example, in the atmosphere) is sucked into the main intake passage through the pore from the other side of the pore, and gas (for example, in the atmosphere) is sucked into the comparative intake passage through the first measurement reference hole. Sucked. Then, by measuring a pressure difference at a predetermined position (for example, an intermediate position) between the main intake passage and the comparison intake passage, each of the first to third measurement reference holes is made to correspond to the pore to be measured. If precisely machined (that is, matched to the shape of the pore to be measured), the absolute value of the pressure difference between the main intake passage and the comparative intake passage can be reduced, and is affected by the measurement environment. The relative conductance of the conductance of the pores and hence the flow rate of the gas flowing through the pores can be accurately measured from the pressure difference.

  In the present invention, there is provided a second measuring means for measuring the pressure difference between the suction port of the suction means and the atmospheric pressure, and the suction speed of the suction means is controlled according to the pressure difference measured by the second measuring means. It is preferable to configure so as to. According to this, by measuring the pressure difference between the atmospheric pressure, the main intake passage, the comparative intake passage, and the suction means at a constant level, the gas flow rate can be measured more accurately without being affected by fluctuations in the atmospheric pressure. can do.

  In the present invention, it is preferable that at least a tip portion of the main intake passage is formed of a flexible member, and one end of the flexible member is provided with a suction pad. According to this, when the measurement object is each pore of the shower plate used in the CVD apparatus and the flow rate of the gas flowing through these pores is measured, the suction pad is moved to an arbitrary position, By simply pressing the suction pad so that it surrounds the periphery of one side of the pore and adsorbing it, the main intake passage communicates with the pore to prepare for flow measurement. Work can be improved and is advantageous.

  By the way, when a predetermined thin film is formed on a substrate having a predetermined area in a CVD apparatus equipped with a shower plate, if there is variation in the flow rate of gas injected from each pore of the shower plate, Of these, unevenness in film thickness often occurs within a certain range. In such a case, it is possible to further improve the uniformity of the film thickness distribution by managing the total flow rate of the gas injected from the plurality of pores located at the position corresponding to the portion where the film thickness unevenness occurs. it can. Therefore, in the present invention, in the case where a plurality of pores having the same shape are formed in the member, the plurality of pores are set as aggregate pores, and the suction pad surrounds the circumference of the aggregate pores. It can be configured to suck gas simultaneously through the holes. According to this, the total flow rate of the gas injected from the plurality of pores can be managed without changing the configuration of the flow rate measuring device, which is advantageous. In addition, if the suction pad is detachably provided in the main intake passage so that it can be exchanged according to the range in which the film thickness distribution is uneven, the usability is improved.

The figure which shows typically the structure of the flow volume measuring apparatus of embodiment of this invention. The figure explaining the measurement of the gas flow rate with the flow measuring device shown in FIG. The expanded sectional view explaining the modification of a suction pad.

  Hereinafter, with reference to the drawings, a measurement object is showered using a shower plate SP in which a plurality of pores (gas injection ports) H are formed in a predetermined pattern in a plate-like member constituting a gas introduction part of a CVD apparatus. The flow rate measuring device according to the embodiment of the present invention will be described by taking as an example a case where each pore of the plate SP (diameter 0.7 mm, length 20 mm) is measured and the flow rate of the gas flowing through the pore H is measured.

  Referring to FIG. 1, M is a flow rate measuring device of the present embodiment. The flow rate measuring device M includes suction means 1 that sucks at a predetermined pressure lower than atmospheric pressure. The suction means 1 includes a housing 11, and a sirocco fan 12 is built in the housing. The sirocco fan 12 is connected to an output shaft 13a of a servo motor 13 attached to the housing 11, and is driven to rotate at a constant rotational speed. The suction port 14 formed in the housing 11 is provided with a T-shaped joint 14a, and the first pipe 2 constituting the main exhaust passage and the second pipe 3 constituting the comparative exhaust passage are connected to each other. The suction port 14 is provided with a differential pressure gauge (second measuring means) 15 having a known structure for measuring a pressure difference between the suction port 14 and the atmospheric pressure.

In the first pipe 2 and the second pipe 3, cylindrical members 4 ₁ and 4 ₂ are respectively provided at positions equidistant from the T-shaped joint 14a. The cylindrical members 4 ₁ , 4 ₂ are finely machined precisely according to the shape of the pore H to be measured, that is, by matching the inner diameter d and the length l of the pore H to be measured. hole is drilled, a second pore of the tubular member 4 ₂ provided to the pipe 3 constitutes a second metric hole RH2, the first pipe 2 provided with the tubular member 4 ₁ of the hole 3 Measurement reference hole RH3. Further, the first pipe 2 and the second pipe 3 are respectively branched at a position equidistant from the T-shaped joint 14a (preferably, an intermediate position of the entire length of the main intake passage and the comparison intake passage). The pipes 5 ₁ and 5 ₂ are respectively connected to a differential pressure gauge (first measuring means) 6 having a known structure. And each said component is accommodated in the housing F (it shows with the dashed-dotted line in FIG. 1) which can be carried.

Joints (so-called one-touch joints) 7 ₁ and 7 ₂ are provided at the ends of the first pipe 2 and the second pipe 3, respectively. Then, the one of the joint _71, extends outwardly through the housing F, the third pipe 2a constituting the main exhaust passage is connected detachably suction pad 8 to the end of the third pipe 2a It is attached. As the suction pad 8, a known material such as a resin can be used, and a suction part extending from the base end to the third pipe 2 a and extending downward in a skirt shape from the base end to one side peripheral edge of the pore H The flat surface (upper surface in FIG. 1) of the shower plate can be pressed and adsorbed so as to surround the periphery of the portion. Thereby, the 3rd piping 2a and the pore H are mutually connected. Note that the attachment method of the suction pad 8 to the third pipe 2a is not limited as long as it can be attached so as to be kept airtight. Further, the other joint 7 _2, extends outwardly through the housing F, fourth pipe 3a constituting the comparison exhaust passage are connected. As the third pipe 2a and the fourth pipe 3a, synthetic resin air tubes having the same diameter and the same length are used. The end of the fourth pipe 3a is connected to the tubular member 4 ₃ attached to the housing F. In this case, the tubular member 4 _3, in the same manner as described above, precision machined holes to match the form of the pores H to be measured is bored, cylindrical housing 4 ₃ provided in the fourth pipe 3a The hole constitutes the first measurement reference hole RH1.

  The housing F includes a control unit C including a computer, a memory, a sequencer, and the like, and calculates the flow rate of gas flowing through the pores H from the operation of the suction means 1 and the measured value of the differential pressure gauge 6. It is designed to be controlled in an integrated manner. The rotational speed of the servo motor 13 is feedback-controlled based on the measured value of the differential pressure gauge 15 so that the intake speed at the intake port 14 is maintained at a predetermined pressure lower than atmospheric pressure (for example, atmospheric pressure −200 Pa). The Below, the flow measurement of the gas which flows through the pore H using the flow measuring device of this embodiment is demonstrated.

  First, the suction pad 8 of the third pipe 2a is pressed against the shower plate SP so as to adsorb so as to surround the periphery of one side of the pore H (see FIG. 1), and then the suction means 1 is operated. To do. When the main intake passages 2, 2a and the comparison intake passages 3, 3a are respectively sucked by the suction means 1 at a predetermined pressure lower than the atmospheric pressure, the main intake passage 2, Gas (in the atmosphere) is sucked into 2a and gas (in the atmosphere) is sucked into the comparative intake passages 3, 3a through the first measurement reference hole RH1.

Here, with reference to FIG. 2, the gas flow rate flowing through the main intake passages 2 and 2a through the pores H is Q1, the gas flow rate flowing through the comparative intake passages 3 and 3a through the first measurement reference hole RH1 is Q2, and The conductance of the first measurement reference hole RH1 is C1, the conductance of the second measurement reference hole RH2 is C2, the conductance of the third measurement reference hole RH3 is C3, and the conductance of the pore H is C4. _{P 1} the pressure in the main air intake passage 2,2a between H and the third metric hole RH3, the pressure in comparison intake passage 3,3a between both the first and second measurement reference holes RH1, RH2 P ₂ (that is, the pressure difference of the differential pressure gauge 15), the pressure of the suction port 14 leading to the main intake passages 2, 2 a and the comparison intake passages 3, 3 a in the suction means 1 is P ₃ , and the atmospheric pressure is P _0. If The following relationship is established. That is,
_{Q2 = C1 (P 0 -P 2} ) = C2 (P 2 -P 3) ··· ( Equation 1)
_{Q1 = C3 (P 1 -P 3} ) = C4 (P 0 -P 1) ··· ( Equation 2)
From Equation 1 and Equation 2 above,
C4 / C3 = (P ₁ −P ₂ + (P ₀ −P ₂ ) × C 1 / C 2) / (P ₀ −P ₁ ) (Equation 3)

  From the above, the first to third measurement reference holes RH1, RH2, and RH3 are made to correspond to the pore H to be measured (that is, the diameter d and the length l of the pore to be measured are made to coincide with each other). If the machine is precisely machined, the relative conductance of the conductance of the pores H and hence the flow rate of the gas flowing through the pores H can be precisely measured from the pressure difference, that is, the measured value of the differential pressure gauge 15. In this case, the pressure difference measured by the differential pressure gauge 15 is input to the control unit C, and the gas flow rate is instructed based on this pressure difference.

As described above, according to the present embodiment, the first to third are measured by measuring the pressure difference between the main intake passages 2 and 2a and the comparison intake passages 3 and 3a at a predetermined position (for example, an intermediate position). If each of the measurement reference holes RH1 to RH3 is precisely machined corresponding to the hole H to be measured, the absolute value of the pressure difference between the main intake passages 2 and 2a and the comparison intake passages 3 and 3a is obtained. The relative conductance of the conductance C4 of the pore H and the flow rate of the gas flowing through the pore H can be precisely measured from the pressure difference (P ₁ -P ₂ ) without being affected by the measurement environment. it can. Further, in order to control the speed (ie, suction speed) of the servo motor 13 in accordance with the measured value of the second measuring means 15, the atmospheric pressure, the main intake passages 2, 2a, the comparative intake passages 3, 3a, and the suction means 1 are controlled. By measuring while maintaining a constant pressure difference between each other, the gas flow rate can be measured with higher accuracy without being affected by fluctuations in atmospheric pressure. Further, since the third pipe 2a is composed of a flexible air tube, the suction pad 8 is moved to an arbitrary position, and the suction pad 8 is sucked so as to be in close contact with the periphery of the one side periphery of the pore H. It is advantageous to prepare for the flow rate measurement, and as a result, work can be improved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited above. In the above embodiment, the suction means 1 has been described by way of an example including the servo motor 13 and the sirocco fan 12. However, if the suction means 1 can be stably suctioned at a constant suction speed without pulsation, etc. There is no limitation, and for example, a DC motor or the like can be used as a drive source. Moreover, although the case where an air tube was used was demonstrated to the example as each 1st-4th piping, it is not limited to this, You may use metal things. In this case, at least only the 3rd piping 2a should just have flexibility. Furthermore, in the above embodiment, the linear pore H of the shower plate SP is the measurement object, but the measurement object is not limited to this, and the flow rate of the present invention is not limited to this. The gas flow rate can be measured using a measuring device.

  Further, in the above-described embodiment, the suction pad 8 is described as an example in which the suction pad 8 is adsorbed so as to be in close contact with the periphery of the one side periphery of the fine hole H. However, the present invention is not limited to this. . Here, when a predetermined thin film is formed on the substrate by the CVD apparatus provided with the shower plate SP, if the flow rate of the gas injected from each pore H of the shower plate varies, In many cases, unevenness of the film thickness occurs in a certain range, and it is better to manage the total flow rate of the gas injected from the plurality of pores H existing at the position corresponding to the portion where the unevenness of the film thickness occurs. Further improvement in uniformity can be achieved. For this reason, as shown in FIG. 3, each pore H existing within a certain range (that is, a range corresponding to a portion in which the film thickness is uneven) among the pores H formed in the shower plate SP is gathered into a fine cell. With the holes Hs, the suction pad 80 can be configured to simultaneously suck gas through each of the pores H surrounding the aggregate pores Hs. According to this, the total flow rate of the gas injected from the plurality of pores can be managed without changing the configuration of the flow rate measuring device, which is advantageous.

SP ... Shower plate, H ... Fine pore (measurement object), 1 ... Suction means, 14 ... Intake port, 2 ... First pipe (main suction passage), 2a ... Third pipe, 3 ... Second pipe (comparative suction) (Passage), 3a ... fourth pipe (comparative suction passage), RH1 to RH4 ... first to third measurement reference holes, 6, 15 ... differential pressure gauge, 8 ... suction pad.

Claims (1)

A flow rate measuring device for measuring a flow rate of a gas flowing in a pore formed in a member having a predetermined shape as a measurement object,
A suction means for sucking at a predetermined pressure lower than the atmospheric pressure, and a main intake passage and a comparative intake passage respectively connected to the suction means,
The main intake passage is detachably connected to one side of the pore, the comparison intake passage communicates with a first measurement reference hole corresponding to the pore, and the second measurement reference corresponding to the pore is connected to the comparison intake passage. And a third measurement reference hole corresponding to the fine hole is interposed in the main intake passage,
The suction means is operated to suck the gas through the pore and the first measurement reference hole, respectively, and between the pore and the third measurement reference hole, and between the first and second measurement reference holes. Providing a first measuring means for measuring a pressure difference between the intake passage and the comparative intake passage;
A second measuring means for measuring the pressure difference between the suction port of the suction means and the atmospheric pressure is provided, and the suction speed of the suction means is controlled according to the pressure difference measured by the second measuring means. , At least a tip portion of the main intake passage is made of a flexible member, and is provided with a suction pad at one end of the flexible member, and a plurality of pores of the same shape are formed in the member, And the suction pad is configured to simultaneously suck gas through each of the pores surrounding the aggregated pores .

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