JP2017161437A - Device and method for checking for surface deposits - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection device and method, which allow accurately checking for particles and other surface deposits.SOLUTION: A surface deposit inspection device comprises; a cup-shaped covering member 21 having an opening 211 whose edge is brought into contact with a surface 11 under measurement to cover the surface under measurement; electric potential measurement means 22 for measuring electric potential of the surface under measurement; neutralizing means 23 configured to impart neutralizing energy on the surface under measurement to bring the electric potential measured by the electric potential measurement means to zero or close to zero; agitation means 24 for agitating the air inside the covering member; suction means 25 for sucking the air inside the covering member; and inspection means 26 configured to check for particles contained in the air sucked by the suction means.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inspection apparatus and inspection method for surface deposits for inspecting particles and other contaminants adhered to the surface of an object.

  A surface contamination measuring instrument that captures particles attached to the surface of a semiconductor wafer, liquid crystal glass, organic EL, magnetic disk, IC chip, semiconductor device, or a device for manufacturing / inspecting these, and analyzes the source of the particle It has been known. For example, Patent Document 1 discloses a suction unit that sucks air from the vicinity of a measurement target, a measurement unit that measures the amount and components of particles in the sucked air, and a fluid discharged to the surface of the measurement target. A surface contamination measuring instrument, characterized in that a sampling member disposed close to the surface of a measurement object, and a shielding member made of a flexible member is provided around the sampling member Is disclosed.

JP 2000-321180 A

  In the surface contamination measuring instrument described in Patent Document 1, fluid is discharged onto the surface of the measurement object and air from the vicinity of the measurement object is sucked to thereby determine the amount and components of the particles in the sucked air. It is configured to measure. However, if the measurement object is charged, the particles are strongly adsorbed by static electricity, so that even if the fluid is discharged, not all particles are captured. For this reason, it cannot be said that the measurement accuracy of particles is high.

  The problem to be solved by the present invention is to provide an inspection apparatus and an inspection method capable of accurately inspecting particles and other surface deposits.

  In the present invention, the edge of the opening of the cup-shaped covering member is brought into contact with the measurement target surface, the measurement target surface is covered, the potential of the measurement target surface is measured, and the measured potential is zeroed or The problem is solved by applying static elimination energy that approaches zero, sucking air inside the covering member, and inspecting particles in the sucked air.

  According to the present invention, the potential of the surface to be measured is canceled by measuring the potential of the surface to be measured and applying the potential to make the measured potential zero or close to zero, thereby eliminating the adsorption of particles due to static electricity. can do. As a result, particles and other surface deposits can be accurately inspected.

It is a block diagram which shows one Embodiment of the inspection apparatus of the surface deposit | attachment which concerns on this invention. It is the bottom view seen from the direction of arrow II of covering member 21 of FIG. It is a flowchart which shows an example of the test | inspection process which the controller of FIG. 1 performs. It is a graph which shows the relationship between the surface potential of a measurement object surface, and the number of particles measured with the particle counter.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The surface deposit inspection apparatus 2 according to the present embodiment includes, for example, a wall surface, a floor surface, a ceiling surface, a processing apparatus surface, a base surface, a container for housing a semiconductor wafer, etc. Used to analyze the quantity and composition of particles present in the surrounding environment. Such a surface (hereinafter, also referred to as a measurement target surface 11 of the measurement target 1) comes into contact, friction, separation, or collision with an operator's hand (usually wearing resin or rubber gloves) or other objects. Charges up. In particular, in a clean room where the temperature is 20 to 25 ° C. and the humidity is 50% or less, it is easier to be charged than in a high temperature and high humidity environment. If such a measurement object is charged, even if it is measured using a conventional particle counter, the particles are strongly adsorbed to the measurement object surface by static electricity, so that all particles cannot be measured, and the measured values are Smaller than the value. FIG. 4 is a graph showing the relationship between the surface potential of the measurement target surface and the average number of particles per unit area measured by the particle counter. The horizontal axis represents the surface potential, and the vertical axis represents the number of particles measured when the charging potential is 10 times (10x) to 1000 times (1000x) of the leftmost value x. Each of the three lines indicates the measurement result of a different measurement object 1. As shown in the figure, it is understood that in any measurement object 1, the number of particles to be measured becomes smaller as the surface potential becomes larger than the number of particles at the potential x.

  For this reason, as shown in FIG. 1, the surface deposit inspection apparatus 2 according to the present embodiment has a cup-shaped covering member 21 that covers the measurement target surface 11 with the edge of the opening 211 in contact with the measurement target surface 11. A surface potential meter 22 that measures the potential of the measurement target surface 11, a static eliminator 23 that applies to the measurement target surface 11 a potential that makes the potential measured by the surface potential meter 22 zero or close to zero, and a covering member An air supply pump 24 and the like for stirring the air inside 21, a suction pump 25 and the like for sucking air inside the covering member 21, and a particle counter 26 for inspecting particles in the air sucked by the suction pump 25. Prepare. And as shown in FIG. 3, the edge of the opening part 211 of the cup-shaped coating | coated member 21 is made to contact the measurement object surface 11, and the measurement object surface 11 is coat | covered (step ST1), and the electric potential of the measurement object surface 11 is set. Measurement (step ST2), neutralizing energy that makes the measured potential zero or close to zero is applied to the measurement target surface 11 (step ST13), and the air inside the covering member 21 is stirred (step ST9). Air inside the member 21 is sucked (step ST10), and particles in the sucked air are inspected (step ST11).

  The covering member 21 has a cup shape having an opening 211 at one end, and is configured by a rigid body such as metal, ceramic, or resin. When a soft X-ray apparatus is used as the static eliminator 23 to be described later, a plate thickness of 1 mm or more if made of metal and 2 mm or more if made of resin is preferable from the viewpoint of a soft X-ray shielding function. The cross section of the covering member 21 may be either circular or rectangular. A head 212 is provided at the other end of the opening 211 of the covering member 21, and a surface potential meter 22 and a static eliminator 23 are provided on both sides thereof. In order to make the opening 211 of the covering member 21 follow the shape of the measurement target surface 11, a flexible member may be attached to the opening 211 of the covering member 21.

  An air supply pipe 242 and a suction pipe 252 are connected to the head 212. In the covering member 21 of the present embodiment, since the head 212 is fixed to the upper end of the covering member 21, the distance from the head 212 to the measurement target surface 11 is always constant. Therefore, since the balance between air supply and suction on the measurement target surface 11 is constant, there is an advantage that the particle measurement error due to the collection variation can be reduced.

  The surface potential meter 22 is a so-called non-contact potential type, measures the surface potential of the measurement target surface 11 covered with the opening 211, and outputs the data to the controller 28 (specifically, the controller 28 The measurement data of the surface electrometer 22 is read at a predetermined timing).

  The static eliminator 23 applies, to the measurement target surface, static elimination energy that makes the potential of the measurement target surface 11 zero, or static elimination energy that approaches zero. Particularly preferably, the absolute value of the surface potential of the measurement target surface 11 is set to 0 to 1 kV. Examples of the static eliminator 23 include ionizers using corona discharge, soft X-ray irradiation, and ultraviolet irradiation. When an ionizer that ionizes the air inside the covering member 21 by corona discharge is used as the static eliminator 23, in addition to fixing the static eliminator 23 made of an ionizer to the covering member 21, as shown in FIG. A static eliminator made of an ionizer may be provided in an air supply pipe 242 to be described later, and the air supplied from the air supply pump 24 to the inside of the covering member 21 may be ionized. In this case, the supply air may be ionized by soft X-rays instead of corona discharge.

  When the measurement object 1 is in air or an oxygen atmosphere under normal pressure, a soft X-ray irradiation device that irradiates soft X-rays having a wavelength of 1 nm or less and energy of about 0.1 to 5 KeV as the static eliminator 23. Is preferably used. When soft X-rays are irradiated, air molecules are photoionized by photon absorption, and further, the ionized electrons have high energy, so they are ionized by collisions with neutral atoms and molecules. A large number of ion pairs are generated by the avalanche phenomenon. When a soft X-ray irradiation apparatus is used as the static eliminator 23, there is an advantage that only ions are efficiently generated with complete ozone free (no generation of ozone).

  On the other hand, when the measurement object 1 is in an inert gas atmosphere such as nitrogen gas or argon gas and under reduced pressure, the static eliminator 23 has a wavelength of 10 to 400 nm, that is, a soft X-ray with a wavelength shorter than visible light. It is preferable to use an ultraviolet irradiation device that irradiates ultraviolet rays having a longer wavelength. In particular, the charge removal performance by ultraviolet irradiation in a reduced-pressure atmosphere increases dramatically as the vacuum state is approached.

  In the case of using a soft X-ray irradiation device or an ultraviolet irradiation device as the static eliminator 23, in consideration of safety, as shown in FIG. 1, the contact surface between the opening 211 of the covering member 21 and the measurement object 1 is shown. It is desirable that an X-ray measuring device for detecting a soft X-ray dose leaking from the contact surface or an ultraviolet ray measuring device 27 for detecting ultraviolet rays is provided outside the vicinity, and the measurement result is output to the controller. Then, when the leakage of soft X-rays or ultraviolet rays is detected by these X-ray measuring devices or ultraviolet ray measuring devices 27, it is desirable to stop the irradiation of soft X-rays or ultraviolet rays and take measures to urge the leakage.

  When the potential of the measurement target surface 11 is higher than the predetermined threshold by the surface potential meter 22 described above, static elimination energy such as ionized air, soft X-rays, or ultraviolet rays is applied to the measurement target surface 11 using the static eliminator 23. At this time, in order to stir the air in the internal space surrounded by the opening 211 of the covering member 21 and the measurement target surface 11 and to float particles adhering to the measured measurement target surface 11, the covering member 21 is suspended. Air is supplied to the inside. As the air supply means, an air supply pump 24, an air supply pipe 242 having one end connected to the air supply pump 24 and the other end connected to the air blowing hole 243 of the head 212, and an air supply pipe 242 are provided in the middle. And a dust removal filter 241 for removing particles mixed in the supply air. In the covering member 21 of the present embodiment, as shown in FIG. 2, four air blowing holes 243 are provided on the outer periphery of the head 212 at equal intervals. The air sucked by the air supply pump 24 by this air supply means is dust-removed by the dust removal filter 241, and then blown out from the four air blowing holes 243 to the inside of the covering member 21 via the air supply pipe 242. Thus, the inside of the covering member 21 is agitated.

  On the other hand, the air inside the covering member 21 containing particles by being neutralized and stirred is guided to the particle counter 26. As suction means for this purpose, suction pump 25, suction pipe 252 having one end connected to suction pump 25 and the other end connected to air suction hole 253 of head 212, and suction pipe 252 are provided in the middle of suction pipe 252. A particle counter 26 that measures particles mixed in the air by a light scattering method, and a particle collector 251 that is provided in the middle of the suction pipe 252 and collects particles mixed in the suction air are provided. By this suction means, the air inside the covering member 21 is guided to the particle counter 26 by the suction pipe 252, passes through the particle collector 251, and is exhausted from the suction pump 25. The particle counter 26 measures the number of particles mixed in the suction air for each particle size, but the particles collected by the particle collector 251 are supplied to an analysis device or the like to analyze components and the like. It is used to specify the source of particles.

  The controller 28 controls ON / OFF of the static eliminator 23, ON / OFF of the air supply pump 24, ON / OFF of the suction pump 25, and ON / OFF of the particle counter 26. Further, the measurement data of the surface potential meter 22 is read, and the amount of static electricity removed by the static eliminator 23 (for example, the application time of static electricity) is controlled. Further, when the measurement data of the X-ray measuring device or the ultraviolet measuring device 27 is read and leakage of soft X-rays or ultraviolet rays is detected, the operation of the static eliminator 23 is stopped and the operator is informed of the leakage.

  In the embodiment shown in FIG. 1, the air supply pump 24 and the suction pump 25 are provided separately, and the air supply system and the suction system are independent from each other. It is good also as a circulation system by connecting an air supply system and a suction system.

  Next, the usage method of the inspection apparatus 2 of this embodiment is demonstrated. FIG. 3 is a flowchart mainly showing an example of the inspection process executed by the controller 28. First, in step ST <b> 1, the covering member 21 is set on the measurement target surface 11 of the measurement target 1. At this time, particularly when a soft X-ray irradiating device or an ultraviolet irradiating device is used as the static eliminator 23 so that the edge of the opening 211 of the covering member 21 is in contact with the measurement target surface 11, it is preferably set so as to be in close contact. After the opening 211 of the covering member 21 is brought into contact with the measurement target surface 11 and the measurement target surface 11 is covered, in step ST2, the controller 28 reads the measurement data of the surface potential meter 22, and calculates the surface potential of the measurement target surface 11. To grasp.

In step ST3, the set and it is determined whether routine initial (first) and, if a routine for the first time the process proceeds to step ST4, the object surface 11 in the step ST4 is higher than the predetermined value V ₀ values To determine if it is charged. If not charged at a higher value than the predetermined value V ₀ the process proceeds to step ST9. If it is charged at a value higher than the predetermined value V ₀ , the process proceeds to step ST5, and after performing soft X-ray or ultraviolet irradiation for a short time predetermined in step ST5, the process proceeds to step ST6. In step ST 3, the process of steps ST 4 → ST 5 → ST 6 is executed only in the first routine in order to confirm whether or not the covering member 21 is properly set on the measurement target surface 11 of the measurement target 1. is there.

  In the case of the second and subsequent routines after setting in step ST3, the process proceeds from step ST13 to ST6 instead of steps ST4 and ST5. In step ST <b> 13, the controller 28 controls the static eliminator 23 in order to apply the static elimination energy corresponding to the measured potential from the static eliminator 23 to the measurement target surface 11. Here, the static elimination energy corresponding to the measured potential is, for example, when the absolute value of the measured potential of the measurement target surface 11 exceeds 1 kV, the static eliminator 23 is turned on for a time correlated with the exceeded value. For example, when the absolute value of the measured potential of the measurement target surface 11 is 1 kV or less, the static elimination energy is zero, that is, the static eliminator 23 remains OFF.

  In step ST7 following step ST3 → ST4 → ST5 → ST6, the controller 28 reads out the measurement data obtained by the X-ray measuring device or the ultraviolet ray measuring device 27 and softens it from between the opening 211 of the covering member 21 and the measurement target surface 11. Check if X-rays or ultraviolet rays are leaking. In step ST7, if leakage of soft X-rays or ultraviolet rays is confirmed, the process proceeds to step ST12 to turn off the static eliminator 23 and alert the operator to the leakage, and then the process ends.

If no leakage of soft X-rays or ultraviolet rays is confirmed in step ST7, the process proceeds to step ST8, where the controller 28 reads the measurement data of the surface potentiometer 22 again, and the absolute value of the measurement data is a predetermined value V ₀ , for example, It is determined whether the voltage is 1 kV or less. As a result of this determination, if the absolute value of the measurement data exceeds 1 kV (predetermined value V ₀ ), the process returns to step ST2, the potential is measured again (step ST2), and charge removal energy is applied according to the measured potential. (Step ST13), measurement and determination of leakage X-rays or leakage ultraviolet rays (steps ST6 and ST7) are repeated. In step ST8, when the absolute value of the measurement data is 1 kV (predetermined value V ₀ ) or less, the process proceeds to step ST9, and the controller 28 turns on the air supply pump 24 and supplies air into the covering member 21. The ON time of the air supply pump 24 can be set using, for example, a timer. As a result, the air sucked by the air supply pump 24 is dust-removed by the dust removal filter 241 and then blown out from the four air blowing holes 243 to the inside of the covering member 21 via the air supply pipe 242. The inside of 21 will be stirred. Note that steps ST5, ST6, and ST7 can be omitted when using a static elimination method other than X-rays or ultraviolet rays that does not affect the safety of the human body.

  In step ST <b> 10, the controller 28 turns on the suction pump 25 and sucks the air inside the covering member 21. The ON time of the suction pump 25 can be set using, for example, a timer. As a result, the air inside the covering member 21 is guided to the particle counter 26 via the suction pipe 252, passes through the particle collector 251, and is exhausted from the suction pump 25. In step ST11, the controller 28 turns on the particle counter 26 and measures the number of particles. The particles collected by the particle collector 251 are supplied to an analysis device (not shown) and used for identifying the particle generation source by analyzing the particle components and the like.

  As described above, according to the surface adhering matter inspection apparatus 2 of the present embodiment, particles are inspected after neutralizing electricity in various devices, wall surfaces, bases, containers, etc. in a clean room that is easily charged. Therefore, a highly accurate inspection apparatus and inspection method can be provided. In particular, according to the static eliminator 23 using soft X-rays or ultraviolet rays, whether the measurement object 1 is in air or an oxygen atmosphere under normal pressure, nitrogen gas, argon gas, inert gas atmosphere, and under reduced pressure. Therefore, it is possible to exhibit high static elimination efficiency depending on the measurement environment.

DESCRIPTION OF SYMBOLS 1 ... Measuring object 11 ... Measuring object surface 2 ... Inspection apparatus 21 ... Cover member 211 ... Opening part 212 ... Head 22 ... Surface electrometer (potential measuring means)
23 ... Static eliminator (static elimination means)
24 ... Air supply pump (stirring means)
241 ... Dust removal filter 242 ... Air supply pipe (stirring means)
243 ... Air blowing hole (stirring means)
25 ... Suction pump (suction means)
251 ... Particle collector 252 ... Suction piping (suction means)
253 ... Air suction hole (suction means)
26 ... Particle counter (inspection means)
27 ... X-ray measuring device, UV measuring device 28 ... Controller

Claims (9)

A cup-shaped covering member that is in contact with the surface to be measured, and that covers the surface to be measured;
A potential measuring means for measuring the potential of the measurement target surface;
Neutralizing means for applying to the surface to be measured neutralizing energy that makes the potential measured by the potential measuring means zero or close to zero; and
Stirring means for stirring the air inside the covering member;
Suction means for sucking air inside the covering member;
Inspection means for inspecting particles in the air sucked by the suction means;
A surface deposit inspection apparatus comprising:   2. The surface deposit inspection apparatus according to claim 1, wherein the static eliminating unit is a soft X-ray irradiation apparatus that irradiates soft X-rays.   3. The surface-attached surface according to claim 2, wherein an X-ray dose detecting means for detecting a soft X-ray dose leaking from the contact portion is provided outside the vicinity of the contact portion between the opening of the covering member and the measurement target surface. Kimono inspection device. The static elimination means provides a constant static elimination energy immediately after setting the covering member on the measurement target surface,
The surface deposit inspection apparatus according to claim 3, wherein the X-ray dose detection unit detects a soft X-ray dose leaking from the contact portion.   2. The surface deposit inspection apparatus according to claim 1, wherein the static elimination unit is an ultraviolet irradiation device that irradiates ultraviolet rays.   6. The surface deposit according to claim 5, wherein an ultraviolet ray amount detecting means for detecting an ultraviolet ray amount leaking from the contact portion is provided outside the vicinity of the contact portion between the opening of the covering member and the measurement target surface. Inspection equipment. The static elimination means provides a constant static elimination energy immediately after setting the covering member on the measurement target surface,
The said ultraviolet-ray amount detection means is an inspection apparatus of the surface deposit | attachment of Claim 6 which detects the ultraviolet-ray amount which leaks from the said contact part.   8. The surface deposit inspection apparatus according to claim 1, wherein the static elimination unit performs the static elimination process until an absolute value of the potential measured by the potential measurement unit becomes 1 kV or less. The edge of the opening of the cup-shaped covering member is brought into contact with the measurement target surface, the measurement target surface is covered,
Measure the potential of the measurement target surface,
Applying neutralization energy that makes the measured potential zero or close to zero to the surface to be measured,
Stirring the air inside the covering member;
Aspirating the air inside the covering member;
An inspection method for surface deposits that inspects particles in the sucked air.

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