JP2012159421A - Particle measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle measuring instrument which is capable of accurately measuring particles deposited on a target measurement surface of a measurement object regardless of irregularities on the target measurement surface.SOLUTION: A probe P includes: a compressed air introduction port 32 through which compressed air is introduced into the probe P; and at least one columnar floating pad 6 which has an injection port 65 through which the compressed air introduced through the compressed air introduction port is injected to a target measurement surface T, in a lower end surface 64 and is vertically movably disposed in the probe P. The floating pad 6 is held without contacting with the target measurement surface T, by upward force acting on the lower end surface 64 due to a secondary pressure of the compressed air injected through the injection port 65 and flowing in a gap B between the lower end surface 64 and the target measurement surface T.

Description

  The present invention includes a probe for inhaling air containing particles scattered from a surface to be measured by injecting air onto the surface to be measured, and a counter for counting particles contained in the air inhaled by the probe. The present invention relates to a particle measuring apparatus.

  For example, the manufacturing process of a semiconductor device is performed consistently in a clean room maintained at a predetermined cleanliness, but it is generally difficult to completely avoid the adhesion of particles to the substrate surface on which the semiconductor device is formed. is there. When the number of particles adhering to the substrate surface increases, there is a problem that a short circuit of wiring formed on the substrate, metal contamination of the substrate, and the like occur, and the performance of the semiconductor device deteriorates. For this reason, particles adhering to the substrate surface before and after processing, particles adhering to components of semiconductor manufacturing apparatuses such as targets attached in the processing chamber of the sputtering apparatus, and the like are measured and constantly monitored.

  As a particle measuring device used for such particle measurement, a device composed of a hand-held probe and a counter is known (for example, see Patent Document 1). In the thing of the said patent document 1, the probe adhered to the to-be-measured surface by scanning a probe along the to-be-measured surface of a measuring object, and injecting air to the to-be-measured surface from the injection port provided in the probe lower surface. The air containing the scattered particles is sucked from the probe inlet, and the particles contained in the sucked air are counted by a counter.

  Here, when the distance from the ejection port to the measurement surface changes during the scanning of the probe, the air pressure blown to the measurement surface changes accordingly. When the distance from the injection port (ie, the lower surface of the probe) to the surface to be measured increases, the air pressure blown to the surface to be measured decreases, and the particles adhering to the surface to be measured are difficult to scatter. As a result, the measurement accuracy of particles decreases.

  In order to improve the measurement accuracy of particles, it is necessary to keep the distance from the injection port to the surface to be measured constant during particle measurement. However, since scanning of the probe is performed by an operator's hand, it is difficult to keep the distance from the ejection port to the measurement surface constant. In particular, if the surface to be measured for scanning the probe has irregularities, it is extremely difficult to keep the distance from the ejection port to the surface to be measured constant. Therefore, when the measurement surface of the measurement object has irregularities, a decrease in particle measurement accuracy is inevitable.

Patent No. 3920216

  In view of the above points, the present invention provides a particle measuring apparatus capable of accurately measuring particles adhering to a surface to be measured even when the surface to be measured of the object to be measured has irregularities. And

  In order to solve the above problems, the present invention is included in a probe for inhaling air containing particles scattered from a surface to be measured by injecting air onto the surface to be measured of the object to be measured, and air sucked by the probe. In a particle measuring apparatus including a counter for counting particles, a probe includes a compressed air introduction port for introducing compressed air therein, and an injection port for injecting compressed air introduced from the compressed air introduction port to a surface to be measured. And at least one columnar floating pad that is arranged to be movable up and down in the probe, and the floating pad is ejected from the ejection port and is a gap between the lower end surface and the surface to be measured. The second pressure of the compressed air flowing through the air is held in a non-contact manner with respect to the surface to be measured by an upward force acting on the lower end surface.

  According to the present invention, the compressed air introduced from the compressed air introduction port is sprayed from the injection port to the surface to be measured, so that the particles attached to the surface to be measured are scattered and the air containing the scattered particles is sucked by the probe. The particles contained in the sucked air are counted by a counter. At this time, a downward force due to the atmospheric pressure and its own weight acting on the upper end surface acts on the floating pad, but an upward force due to the secondary pressure of the compressed air acts on the lower end surface of the floating pad. Then, the floating pad moves to a position where the downward force and the upward force are balanced, and is held in non-contact with the surface to be measured.

  Here, if there is a recess in the surface to be measured during the scanning of the probe, a gap between the injection port (that is, the lower end surface) of the floating pad and the surface to be measured widens, and the secondary pressure of the compressed air flowing through the gap is increased. Becomes lower. For this reason, the upward force acting on the lower end surface of the floating pad is reduced, and the floating pad moves downward. On the other hand, if there is a convex portion on the surface to be measured during the scanning of the probe, the gap between the lower end surface of the floating pad and the surface to be measured is narrowed, and the secondary pressure of the compressed air flowing through the gap is increased. For this reason, the upward force acting on the lower end surface of the floating pad increases, and the floating pad moves upward. In this way, even if the measurement surface to be scanned with the probe has irregularities, the floating pad moves up and down following the irregularities, so that the gap between the lower end surface of the floating pad and the measurement surface is kept constant. It is. Therefore, even if the measurement surface has irregularities, particles adhering to the measurement surface can be accurately measured.

  In order to scatter particles adhering to the surface to be measured, it is desirable to increase the secondary pressure of the compressed air injected from the injection port. However, increasing the secondary pressure of the compressed air increases the upward force. Thus, the lower end surface of the floating pad is too far away from the surface to be measured. In this case, if the floating pad is made of a material with high specific gravity and the downward force is increased, the distance between the lower end surface of the floating pad and the surface to be measured can be appropriately secured even if the secondary pressure is increased. it can. However, this increases the total weight of the probe and deteriorates the operability of the probe by the operator.

  In the present invention, the floating pad is formed in a stepped columnar shape whose diameter is lower than that of the upper part, and 1 of the compressed air introduced from the compressed air introduction port into the upper end of the diameter-enlarged part of the floating pad. It is preferable that a downward force due to the next pressure acts. According to this, even if the secondary pressure of the compressed air is increased, the downward force acting on the floating pad is increased by the primary pressure of the compressed air, so that the gap between the lower end surface of the floating pad and the surface to be measured is increased. The distance can be secured appropriately. Further, since it is not necessary to form the floating pad with a material having a large specific gravity, the total weight of the probe is not increased.

  Moreover, in this invention, it is preferable to provide a throttle member in the flow path communicating with the injection port formed in the floating pad. According to this, when the flow velocity of the air injected from the injection port is increased and the distance between the lower end surface of the floating pad and the measured surface is long, the downward suction force due to the Bernoulli effect acts on the floating pad. To do. As a result, when the distance between the lower end surface of the floating pad and the surface to be measured becomes shorter, the downward force and the upward force due to the secondary pressure are balanced. And if the distance between the bottom surface of the floating pad and the surface to be measured is shortened, the air pressure blown to the surface to be measured becomes high, so that the particles adhering to the surface to be measured are likely to scatter and the particle measurement accuracy is improved. It can be further improved.

  By the way, in the above-mentioned conventional example, the air flow rate injected from the probe to the surface to be measured and the air flow rate sucked by the probe and guided to the counter are substantially equal. Here, in general, an allowable flow rate of air is determined in a counter, and a counter having a large allowable flow rate is expensive. Therefore, using a counter having a large allowable flow rate causes an increase in cost. On the other hand, if the flow rate of air injected to the surface to be measured is reduced, particles attached to the surface to be measured are difficult to scatter, and the measurement accuracy is reduced. On the other hand, in the present invention, if an exhaust port for exhausting a part of the air flowing through the gap is provided in the lower part of the probe, the flow rate of air flowing into the counter is reduced, so that the allowable flow rate is low and inexpensive. A counter can be used, and there is an advantage that the cost is not increased. Moreover, since it is not necessary to reduce the flow rate of air injected onto the surface to be measured, the measurement accuracy is not lowered.

  In the present invention, a branch path branched from the exhaust path connected to the exhaust port may be communicated with the counter. According to this, since the exhaust port can be used also as the suction port, the structure of the probe may be simplified.

  In the present invention, it is preferable to further include a fan communicating with the exhaust port. According to this, since the amount of air exhausted from the exhaust port can be adjusted by operating the fan, the flow rate of the air flowing into the counter can be adjusted. In this case, it is preferable that the counter includes a flow rate detection unit that detects the flow rate of air flowing in from the probe, and adjusts the rotational speed of the fan based on the detection result of the flow rate detection unit.

The perspective view which shows the particle | grain measuring apparatus of embodiment of this invention. The top view of the probe main body shown in FIG. Sectional drawing along the III-III line of FIG.

  Hereinafter, a particle measuring apparatus according to an embodiment of the present invention will be described with reference to the drawings. Referring to FIG. 1, M is a particle measuring device. The particle measuring device M includes a probe P and a counter C. Here, since the thing of a well-known structure can be used as the counter C, description about the specific structure of the counter C and the particle counting method in the counter C is abbreviate | omitted here.

  The probe P includes a probe main body 1 and a handle 2. 2 and 3, the probe body 1 includes a first base 3, a second base 4 provided on the lower side of the first base 3, and a jacket 5 surrounding the second base 4. Consists of The first base 3 is formed with a through hole 30 penetrating the center in the vertical direction, and the second base 4 is integrally formed with a protrusion 40 extending upward from the center of the upper surface thereof. The first and second bases 3, 4 and the jacket 5 are fixed with screws 10 in a state where the protrusion 40 is inserted into the through hole 30.

  A fixed plate 20 is provided at one end of the handle 2. The fixed plate 20 includes a base portion 21 having a circular shape in plan view and a convex portion 22 having a rectangular shape in plan view protruding outward from one place around the base portion 21. The base 21 is fixed to the upper surface of the first base 3 with screws 11. A plurality of through holes are formed in the base portion 21 so as to pass through the protrusions 40 and upper portions of the floating pads 6 described later. The convex portion 22 is formed with a through hole through which an exhaust pipe 7 described later is inserted. A grip 23 is attached to the upper side of the other end of the handle 2 so that the operator can scan the probe P. An exhaust fan 24 is attached to the lower side of the grip 23.

  The first and second bases 3 and 4 are formed with through holes 31 and 41 communicating with each other, and the floating pad 6 is inserted into the through holes 31 and 41. In the present embodiment, three floating pads 6 are arranged at equal intervals in the circumferential direction on a circle concentric with the centers of both bases 3 and 4.

  A stopper 61 is provided in the vicinity of the upper end surface 60 of the floating pad 6 to restrict the downward movement of the floating pad 6. The stopper 61 includes, for example, a washer 61a and an E clip 61b for preventing the washer 61a from coming off. The floating pad 6 has a columnar shape whose diameter is expanded in two stages from the upper part. The diameter d1 of the upper part of the floating pad 6 shown in FIG. 3 is, for example, 6 mm, and the diameter d2 of the first-stage expanded part below the upper part is, for example, 7.7 mm. The diameter d3 is 9 mm, for example. When the stepped portion 62 at the upper end of the first-stage diameter-expanded portion contacts the lower surface of the first base portion 3, the upward movement of the floating pad 6 is restricted. For this reason, the floating pad 6 can move up and down by an amount (for example, 1 mm) indicated by a symbol D in FIG.

  On the side surface of the first base 3, three compressed air inlets 32 are opened corresponding to the three floating pads 6. Each compressed air introduction port 32 is connected to a pipe leading to a compressed air supply source (not shown) so that the compressed air can be introduced into the first base 3. A flow path 33 communicating with the compressed air introduction port 32 is formed in the first base 3. The flow path 33 extends in the horizontal direction to the side surface of the floating pad 6 and then bends downward to reach the stepped portion 62 of the floating pad 6. When compressed air is supplied to the stepped portion 62 through the flow path 33, a downward force due to the primary pressure (for example, 5 atm) of the compressed air acts on the stepped portion 62.

  In the second base 4, a flow path 42 that extends the flow path 33 of the first base 3 downward is formed. A flow path 63 communicating with the flow path 42 is formed in the floating pad 6. The flow path 63 extends horizontally to the vicinity of the central axis of the floating pad 6 and bends downward to reach the lower end surface 64. The lower end surface 64 of the floating pad 6 is provided with an injection port 65 communicating with the flow path 63 so that compressed air can be injected. The air injected from the injection port 65 flows through the gap B between the lower end surface 64 of the floating pad 6 and the surface T to be measured, and is 2 lower than the primary pressure of the compressed air on the lower end surface 64 of the floating pad 6. An upward force due to the next pressure (for example, 3 atm) is applied.

  In addition, as shown by the phantom line in FIG. 3, if an orifice serving as the throttle member 66 is disposed in the flow path 63 in the floating pad 6, the flow velocity of the air injected from the injection port 65 can be increased. In order to increase the flow velocity of the air injected from the injection port 65, a short pipe as the throttle member 66 may be inserted in the flow path 63, and a countersunk screw may be disposed in the injection port 65.

  In the center of the lower end surface 43 of the second base 4, a suction port 44 for sucking air flowing through the gap B is opened. A suction path 45 extending upward from the suction port 44 and reaching the upper end of the protrusion 40 is formed in the second base 4. The upper end of the suction passage 45 exposed at the upper end surface of the protrusion 40 communicates with the counter C via a pipe (not shown).

  The lower surface of the jacket 5 is an open surface. Then, an exhaust port 51 composed of an annular gap between the inner circumferential surface of the jacket 5 and the outer circumferential surface 46 of the second base 4 is provided on the lower surface of the probe body 1, and a part of the air flowing through the gap B is provided. It is possible to exhaust. An exhaust passage 52 communicating with the exhaust port 51 is formed in the jacket 5. The other end of the exhaust passage 52 exposed on the upper surface of the jacket 5 is connected to the fan 24 via the exhaust pipe 7 so that the exhaust amount from the exhaust port 51 can be increased by operating the fan 24. The counter C is provided with a flow rate detection unit that detects the flow rate of air flowing into the counter C, and the rotation speed of the fan 24 is controlled by a control unit (not shown) based on the detection result of the flow rate detection unit. You may comprise so that it may adjust.

  The exhaust pipe 7 extends upward from the upper surface of the jacket 5 and is inserted into a through-hole formed in the convex portion 22 of the fixing plate 20, and a flexible pipe 72 connected to the upper end of the pipe 71. It consists of A flange 73 connected to the upper end of the pipe 71 is provided at one end of the flexible pipe 72, and the flange 73 is fixed to the convex portion 22 with a screw 73a. The other end of the flexible pipe 72 is connected to the fan 24 so that the air sucked from the exhaust port 51 can be exhausted to the atmosphere.

  According to the present embodiment, when compressed air is introduced into the compressed air introduction port 32 while the probe P is scanned on the measurement target surface (for example, target surface) T by the operator's operation of the handle 2, the injection is performed from the injection port 65. The blown air is blown onto the surface T to be measured, the particles adhering to the surface T to be measured are scattered, the air containing the scattered particles is sucked from the suction port 44, and the particles contained in the sucked air are counted by the counter C. Is counted. At this time, a downward force due to its own weight, atmospheric pressure acting on the upper end surface 60, and primary pressure of compressed air acting on the stepped portion 62 acts on the floating pad 6, and the lower end surface 64 of the floating pad 6. An upward force due to the secondary pressure of the compressed air flowing through the gap B between the lower end surface 64 and the measured surface T acts on the. Then, the floating pad 6 moves to a position where the downward force and the upward force are balanced, and is held in non-contact with the measurement surface T.

  Here, if there is a recess in the measured surface T during the scanning of the probe P, the vertical width of the gap B between the lower end surface 64 of the floating pad 6 and the measured surface T increases, and the compression flowing through the gap B Since the secondary pressure of air becomes low, the upward force acting on the lower end surface 64 of the floating pad 6 decreases, and the floating pad 6 moves downward. Then, when the secondary pressure increases with the downward movement and the vertical width of the gap B decreases to a predetermined amount, the downward force and the upward force are balanced. Further, if there is a convex portion on the measurement surface T during the scanning of the probe P, the vertical width of the gap B becomes narrow, and the secondary pressure of the compressed air flowing through the gap B becomes high. The upward force acting on the end face 64 increases, and the floating pad 6 moves upward. Then, as the secondary pressure decreases with the upward movement and the vertical width of the gap B increases to a predetermined amount, the downward force and the upward force are balanced. Thus, even if the measurement surface T is uneven, the floating pad 6 moves up and down following the unevenness, so that the gap B between the lower end surface 64 of the floating pad 6 and the measurement surface T is constant. Kept. Therefore, even if the surface to be measured T has irregularities, particles adhering to the surface to be measured T can be accurately measured.

  By the way, if all the air jetted from the jet port 65 of the floating pad 6 is sucked from the suction port 44, the flow rate of the air flowing into the counter C increases, and the counter C having a large allowable flow rate must be used. As a result, there is a risk of increasing the cost. On the other hand, in this embodiment, a part of the air flowing through the gap B between the lower end surface 64 of the floating pad 6 (that is, the lower surface of the probe P) and the measurement surface T is sucked from the suction port 44 and remains. The air is sucked into the exhaust port 51 and exhausted into the atmosphere through the exhaust pipe 7 and the fan 24. For this reason, the flow rate of the air flowing into the counter C can be suppressed, it is possible to use a counter with a relatively small allowable flow rate, and there is an advantage that an increase in cost can be prevented.

  Further, if the throttle member 66 is provided in the flow path 63 communicating with the injection port 65, the flow velocity of the air injected from the injection port 65 is increased, and the gap between the lower end surface 64 of the floating pad 6 and the measured surface T is increased. If the distance is relatively long, a downward suction force due to the Bernoulli effect acts on the floating pad 6. As a result, when the distance between the lower end surface 64 of the floating pad 6 and the surface T to be measured becomes shorter, the downward force and the upward force due to the secondary pressure are balanced. When the distance between the lower end surface 64 of the floating pad 6 and the surface to be measured T is shortened, particles attached to the surface to be measured T are likely to scatter and the particle measurement accuracy can be further improved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said thing. For example, in the above embodiment, the probe main body 1 having three floating pads 6 has been described as an example. However, the probe main body 1 only needs to have at least one floating pad 6.

  In the above embodiment, the case where the stepped columnar floating pad 6 is used has been described. However, the shape of the floating pad 6 is not limited to this, and may be a columnar shape (for example, a columnar shape). In this case, a downward force due to atmospheric pressure and its own weight acting on the upper end surface and an upward force due to the secondary pressure of compressed air acting on the lower end surface of the floating pad act on the floating pad. Then, the floating pad moves to a position where the downward force and the upward force are balanced, and is held in non-contact with the surface to be measured.

  However, if the secondary pressure of the compressed air is increased in order to facilitate the scattering of particles, the upward force becomes larger than the downward force, and the lower end surface 64 of the floating pad 6 is too far away from the measured surface T. End up. In this case, if the floating pad 6 is formed of a material having a large specific gravity and the downward force is increased, the distance between the lower end surface 64 of the floating pad 6 and the measured surface T is increased even if the secondary pressure is increased. Can be secured appropriately. However, this increases the total weight of the probe and deteriorates the operability of the probe P by the operator.

  Therefore, when the secondary pressure of the compressed air is increased, the floating pad 6 is formed in a stepped columnar shape as in the above embodiment, and the step 62 at the upper end of the enlarged diameter portion is caused by the primary pressure of the compressed air. It is preferable that a downward force is applied. According to this, even if the secondary pressure of the compressed air is increased, the downward force acting on the floating pad 6 due to the primary pressure of the compressed air increases, so the lower end surface 64 of the floating pad 6 and the surface T to be measured T The distance between can be secured appropriately. Further, since it is not necessary to form the floating pad 6 with a material having a large specific gravity, the total weight of the probe P is not increased.

  In the above embodiment, the suction port 44 communicating with the counter C is provided separately from the exhaust port 51, but a branch pipe branched from the exhaust pipe 7 connected to the exhaust port 51 is communicated with the counter C. May be. According to this, since the exhaust port 51 can be used also as the suction port, and the suction port 44 and the suction path 45 do not have to be formed in the second base 3, the structure of the probe P can be simplified and the cost can be reduced. Can do.

  M ... Particle measuring device, P ... Probe, C ... Counter, T ... Surface to be measured, 6 ... Floating pad, 7 ... Exhaust pipe, 24 ... Fan, 32 ... Compressed air inlet, 44 ... Inlet, 62 ... Stage Part, 51 ... exhaust port, 64 ... lower end surface, 65 ... injection port.

Claims (7)

A particle measuring apparatus comprising: a probe for inhaling air containing particles scattered from the surface to be measured by injecting air onto the surface to be measured; and a counter for counting particles contained in the air inhaled by the probe In
The probe has a compressed air introduction port for introducing compressed air therein, and an injection port for injecting the compressed air introduced from the compressed air introduction port to the measurement surface at the lower end surface. And at least one columnar floating pad arranged freely,
The floating pad is not applied to the surface to be measured by an upward force acting on the bottom surface by the secondary pressure of compressed air that is injected from the injection port and flows through the gap between the bottom surface and the surface to be measured. A particle measuring apparatus configured to be held in contact.   The floating pad is formed in a stepped cylindrical shape with the diameter lower than the upper part, and the primary pressure of the compressed air introduced from the compressed air introduction port into the upper end of the diameter-enlarged part of the floating pad. 2. A particle measuring apparatus according to claim 1, wherein a downward force is applied.   The particle measuring apparatus according to claim 1, wherein a throttle member is provided in a flow path communicating with the ejection port formed in the floating pad.   The particle measuring apparatus according to any one of claims 1 to 3, wherein an exhaust port for exhausting a part of the air flowing through the gap is provided on a lower surface of the probe.   5. The particle measuring apparatus according to claim 4, wherein the probe further includes an exhaust path connected to the exhaust port and a branch path branched from the exhaust path, and the branch path communicates with the counter. .   6. The particle measuring apparatus according to claim 4, further comprising a fan communicating with the exhaust port. The counter includes a flow rate detection unit that detects a flow rate of air sucked from the probe,
The particle measuring apparatus according to claim 6, wherein a rotation speed of the fan is adjusted based on a detection result of the flow rate detection unit.

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