JPH08313486A - Method and apparatus for detecting charge quantity of static electricity of insulating substrate - Google Patents

Abstract

PURPOSE: To independently calculate the charge quantities of the upper and rear surfaces of an insulating substrate by opposing an earth plate and a surface potential detecting probe to each other on both sides of an insulating substrate to be measured through a definite gap. CONSTITUTION: The surface potential of the upper surface of a substrate 1 is measured and the substrate 1 is turned over to measure the surface potential of the rear surface of the substrate 1. The charge densities of static electricity on the upper and rear sides of the substrate 1 are calculated from the measured values of the surface potentials. Herein, the thickness of an insulating spacer 5, that is, the distance (d) between the rear surface of the substrate 1 and an earth plate 2 is set so that the electrostatic capacity Cd between the rear surface of the substrate 1 and the earth plate 2 is made larger than 1/10 the electrostatic capacity Cg of the substrate 1 itself to enable further accurate evaluation. Only by moving the probe 3a of a surface electrometer 3 so as to hold a definite gap from the substrate 1, the charge quantities of static electricity at a plurality of places can be measured and the distribution state thereof can be known.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting static electricity of an insulating substrate for a liquid crystal display device and the like, and a detection device used therefor.

[0002]

2. Description of the Related Art For example, in a liquid crystal display device, a liquid crystal material is sandwiched between an insulating substrate provided with a switching element, an electrode film and the like on its surface and another insulating substrate provided with an electrode film and the like. Is configured. In the manufacturing process of this liquid crystal display device, the insulating substrate is likely to be charged with static electricity due to friction such as peeling of the insulating substrate from the heating plate in the heat treatment and rubbing process, and plasma irradiation for etching. May be discharged. Due to this discharge, the switching element formed on the surface of the insulating substrate may be damaged or the electrode film may be broken, resulting in a failure. Therefore, it is extremely useful to accurately grasp the electrostatic charge state on the surface of the insulating substrate and to take effective discharge prevention measures and static elimination measures in order to improve the product yield.

In order to measure the amount of static electricity, a method of measuring the surface potential of the object to be measured has been conventionally used.
As an example, as shown in FIG.
There is a static electricity measuring device disclosed in Japanese Patent No. In FIG. 4, 101 is an object to be measured for measuring the amount of static electricity on an insulating film provided on the surface of a semiconductor substrate, 102 is a piezoelectric element that is a drive mechanism, 103 is an electrode, and 104 is an ammeter that is a current detection means. , 105 is a grounded stage, 106
Is an electrostatic shield.

An object 101 to be measured is fixed on a stage 105, and its back surface is electrically grounded via the stage 105. The electrode 103 vibrates up and down by the piezoelectric element 102 that is a driving mechanism, and the electrode 103 and the DUT 1
The distance from 01 changes periodically. This piezoelectric element 102
The electrode and the electrode 103 are connected by an arm having an appropriate length, and the vibration of the piezoelectric element is magnified by the lever principle. As a result, the electrostatic capacitance between the electrode 103 and the DUT 101 changes, and the DUT 1
When the surface of 01 is charged, a current flows through the electrode 103. This is detected by the current detecting means 104.
The detected current I [A] is the potential of the DUT 101 being V
[V], the distance between the object to be measured 101 and the electrode 103 is D [m], the capacitance is C [F], and the effective area of the electrode 103 is S [m ² ] and is expressed by the following equation (1). Be done.

[0005]

[Equation 2]

Here, in the right side of the equation (1), other than V is known, so that the potential V of the object 101 to be measured can be measured from the current I.

[0007]

In the conventional method for detecting the amount of electrostatic charge charged on the substrate, as described above,
The object to be measured was fixed to a grounded stage, and the surface charge potential was used to detect the amount of charge.Therefore, if the substrate is, for example, a semiconductor substrate and charging on the back surface does not pose a problem, the measured object should be measured. If an object is an insulating board, such as an insulating board, and if both sides are insulative plates, it is not clear before the measurement whether the front side or the back side is charged.
It cannot detect how much static electricity is charged on which surface. Also, when both sides of the insulating substrate are charged, the back side is grounded through the stage when measuring the front side, so the charge accumulated on the back side leaks and the charge amount on the back side is measured. I can't.
Further, after the front side is measured, when the insulating substrate is separated from the stage, peeling charge is newly generated between the back side of the substrate and the stage, and indeterminate static charge is generated on the insulating substrate. For these reasons, in the conventional method, when electric charges are accumulated on the front and back surfaces of the insulating substrate and accumulated, the amount of charge on each surface cannot be obtained.

On the other hand, even if an electrode film or a switching element is not provided on the back side of the substrate, if the amount of charge on the back side increases, it may wrap around to the front side and discharge.
Problems such as switching element destruction and electrode film disconnection occur, and it is necessary to accurately grasp the static charge on the back surface side and eliminate the static electricity.

Therefore, for example, when the static electricity of the substrate is removed by ion irradiation, effective charge removal cannot be performed unless the surface is charged and the amount of charge is grasped before ion irradiation. The method (1) has a problem that only the electrostatic charge amount on one side can be detected, and the detection result does not serve as an effective guideline for static elimination.

The present invention has been made in order to solve such a problem, and in order to obtain an effective guideline for static elimination, it is possible to independently obtain the charge amounts of the front and back surfaces of the insulating substrate. An object of the present invention is to provide an electrostatic charge amount detection method and a detection device therefor.

[0011]

According to the method for detecting the amount of electrostatic charge of an insulating substrate of the present invention, (a) a potential probe of a surface electrometer is provided on one surface side of the insulating substrate at a certain distance. A grounding plate is provided on the other surface side of the substrate facing the potential probe with a certain distance from the substrate, and the surface potential meter measures the potential V ₁ of the _one surface of the substrate,
(B) The potential V ₂ on the other surface side of the substrate is measured by the same method as in (a), and (c) the capacitance per unit area of the air gap between the surface of the substrate and the ground plate is Cd. , The capacitance per unit area of the substrate is Cg, 1 / C = 1 /
The electrostatic charge density Q ₁ on one surface side of the substrate and the electrostatic charge density Q ₂ on the other surface side of the substrate are defined as Cd + 1 / Cg.

[0012]

(Equation 3)

It is characterized by being obtained by

The detection of the amount of electrostatic charge at a plurality of points on the insulating substrate and the detection of the tendency of the distribution of the amount of electrostatic charge on the surface of the substrate are effective in elucidating the cause of charging and improving the effect of static elimination. preferable.

The contact between the substrate and the substrate is such that the capacitance per unit area formed by the gap between the substrate surface and the ground plate is 1/10 or more of the capacitance per unit area of the substrate itself. By setting the gap with the ground plane, it is possible to accurately separate the difference in the surface potentials generated by the electric charges on the front and back of the substrate, and it is possible to accurately detect the amount of electric charges on the front and back. It is preferable in terms.

The electrostatic charge detector of the present invention comprises a mounting table for partially supporting an insulating substrate for measuring the electrostatic charge, and the substrate on one side of the substrate mounted on the mounting table. And a potential probe is provided on the other side of the substrate opposite to the one side opposite to the ground plate so as to measure a potential of the surface of the substrate. And a surface electrometer having the above-mentioned potential probe.

A calculation means for calculating the electrostatic charge amount on the surface of the substrate from the potential measured by the surface electrometer is further provided, and the charge amount can be directly displayed by measuring the potential. It is preferable because it is possible.

The ground plate is made of a conductive plate material, and the mounting table is a spacer provided on the ground plate.
This is preferable because it is possible to measure the potentials at a plurality of points on the substrate and to know the charge distribution on the substrate simply by moving the potential probe.

The mounting table is also used as a transport means for transporting the substrate in a direction parallel to the surface of the substrate, and the ground plate and the surface electrometer are provided on both sides of the substrate transported by the transport means. And a first surface potential measuring means composed of a first potential probe and a first ground plate of a surface electrometer provided so as to have a constant gap, and the substrate of the first probe and the first ground plate. And a second surface potential measuring means composed of a second probe and a second ground plate of the surface electrometer provided in the same manner as the first surface potential measuring means. This is preferable because it is possible to detect the amount of electric charge directly charged in the manufacturing process line and to eliminate the electric charge without interruption.

A set of surface potential measuring means formed by arranging the first and second surface potential measuring means along the conveying direction of the substrate is arranged in the conveying direction of the substrate. It is preferable to provide a plurality of sets in the direction perpendicular to the above because the in-plane distribution of the surface charges can be accurately and easily measured while the insulating substrate is being transported.

When the length of each side of the ground plate is formed larger than the distance between the ground plate and the potential probe facing the ground plate, the parallel plate has a capacitance relative to the ground portion of the measurement region. Since the capacitance of the capacitor is accurately defined and its value can be easily known, it is preferable that the charge density can be accurately obtained when the charge density is obtained from the potential measurement value.

The capacitance per unit area formed by the gap between the surface of the insulative substrate placed on the mounting table and the ground plate is 1/10 of the capacitance per unit area of the substrate. As described above, the provision of the ground plate makes it possible to accurately separate the difference in the surface potentials generated by the electric charges on the front and back sides of the substrate, and the electric charges on the front and back sides can be accurately separated. It is preferable because it can be accurately detected.

[0023]

According to the electrostatic charge detecting method of the present invention, the ground plate and the probe for detecting the surface potential are opposed to each other on both sides of the insulating substrate to be measured with a constant gap therebetween so that one of the substrates can be measured. The surface potential is measured, and then the potential of the other surface of the substrate is measured in the same manner, and the electrostatic charge amount charged on both surfaces is detected from the potentials on both surfaces. It is possible to accurately grasp whether or not only static electricity is charged, and it is possible to accurately eliminate static electricity.

Further, since it is not a method of directly contacting with a ground plate as in the conventional method, it is not only possible to accurately detect the charge amount on the back surface side, but also it is necessary to separate the substrate from the ground plate after the measurement. In addition, the electrostatic charge is not newly charged on the substrate during the separation.

Further, by detecting the amount of charged electric charge at a plurality of points on the substrate, the tendency of the electric charge distribution on the substrate can be known, the effect of static elimination can be further enhanced, and the cause of the electrostatic charge can be grasped. You can also

According to the electrostatic charge detector of the present invention,
Since the grounding plate is provided on one side of the substrate with a constant gap by placing the insulating substrate on the mounting table of the substrate, accurate measurement can be made by the surface electrometer provided on the other side of the substrate. The potential can be measured and the amount of electrostatic charge can be detected. Moreover, since the insulating substrate is not in direct contact with the ground plate, it is possible to accurately detect the amount of electrostatic charge on the back surface side, and even when the insulating substrate is removed from the mounting table, it does not contact the mounting table. Since the part is small, even if static electricity is generated, it is small and does not affect the measured value.

With the structure according to the sixth aspect, the electrostatic charge distribution on the surface of the insulating substrate can be known only by measuring the potential while moving the potential probe of the surface electrometer on the surface of the insulating substrate. be able to.

Further, according to the structure described in claim 7, the first and second potential measuring means composed of the potential probe of the surface electrometer and the ground plate have the probes on both surfaces of the insulating substrate. As described above, since at least two sets are provided, it is possible to detect the electrostatic charge amount on both surfaces while transporting the insulating substrate. Therefore, it is possible to accurately measure the amount of electric charges charged on both surfaces while being conveyed during the manufacturing process, to understand the cause of easy charging, and to quickly eliminate the charge to prevent the occurrence of defects. .

[0029]

【Example】

Embodiment 1 Next, an embodiment of the electrostatic charge amount detection method and apparatus of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 is an insulating substrate which is an object to be measured.
Glass substrate for liquid crystal display device with dimensions of 300 mm x 40
The thickness is 0 mm, the thickness is 1 mm, and the relative dielectric constant is 6. 2 is a ground plate, for example, SUS made 500 mm x 500 mm,
Conductive plate material having a thickness of about 2 mm, 3 is a surface electrometer, 3a
Is the probe of the surface electrometer. Reference numeral 5 denotes an insulating spacer fixed to the ground plate 2 and made of, for example, polytetrafluoroethylene having a thickness of about 1 mm. The insulating spacer 5 serves as a mounting table on which the insulating substrate 1 is mounted.

First, as to the front side of the insulating substrate 1, FIG.
As shown in, the surface side of the substrate 1 is faced up, and the surface potential of the surface is measured, and the value is defined as V ₁ . Next, the substrate 1 is turned upside down, the back side is faced up, and the surface potential of the back side is measured, and the value is defined as V ₂ .

[0031] The electrostatic charge density charged on the front side and the back side of the substrate 1 and Q _1, Q _2, respectively, from the measured values V ₁ and V ₂ of the surface potential is example as measured by this configuration, the Q _1, Q ₂ The method of finding is shown below. Since the surface potential V _{1 on the} front side is a superposition of the potential induced by the charge Q ₁ and the potential induced by the charge Q ₂ , the measured value V ₁ and the accumulated charge densities Q ₁ , Q ₂ of the substrate 1 are The following relationships are established between them. Here, Cd represents the capacitance per unit area of the air gap between the substrate 1 and the ground plate 2, and Cg represents the capacitance per unit area of the substrate 1.

[0032]

[Equation 4]

The measured value V ₂ is as follows by replacing Q ₁ and Q ₂ in the above equation.

[0034]

(Equation 5)

Cd is the substrate 1 and the ground plate 2 when measuring the surface potential.
And Cg are also known from the physical property values of the substrate 1. In the embodiment shown in FIG. 1, the gap d between the substrate 1 and the ground plate 2 is 1 mm, and the thickness g of the substrate 1 is 1 mm.
Since the relative dielectric constant ε _r of the glass that is the material of the substrate 1 is 6, Cd = 8.854 × 10 ⁻¹³ [F / cm ² ], Cg
= 5.312 × 10 ^-12 [F / cm ² ]. Cd and C
If the series coupling capacitance with g is C, then 1 / C = 1 / Cd +
Since it is 1 / Cg, C = 7.589 × 10 ⁻¹³ [F /
cm ² ].

The above equation (3) is as follows.

[0037]

(Equation 6)

From this, the charges Q ₁ and Q ₂ accumulated on both sides of the substrate are as follows.

[0039]

(Equation 7)

From the equation (4), the measured value of the surface potential V
_{From 1} [V] and V ₂ [V], electrostatic charge densities Q ₁ [C / cm ² ] and Q ₂ [C / cm ² ] charged and accumulated on the respective surfaces
Can be requested.

For example, the measured surface potential is V ₁ = -85.
When 7 [V] and V ₂ = −1000 [V], Q ₁ = −1.02 [pC / cm ² ] and Q ₂ = from the formula (4).
It becomes −760.35 [pC / cm ² ] and it can be seen that most of the charges are accumulated on the back side of the substrate. Therefore, it is not effective to irradiate the front side of the substrate with ions by judging only from the measurement result of V ₁ when removing electricity from the substrate, and Q ₁ and Q ₂ obtained from the measurement results of both V ₁ and V ₂ are not effective. From this, it is found that it is effective to irradiate the back side of the substrate with ions.

Further, for example, V ₁ = 0 [V], V ₂ = -1
If it is 000 [V], Q ₁ = 2450 [pC /
cm ² ], Q ₂ = −2860 [pC / cm ² ] and even if the surface potential on the front side is zero, the insulating substrate 1 has a surface,
It can be seen that charges are accumulated on the back.

Since the insulating substrate 1 is supported by the insulating spacers 5, it is possible to prevent the accumulated charges of the substrate 1 from leaking to the ground plate 2 and to move the substrate 1 from the ground plate 2 to the ground plate 2. Since it is possible to prevent so-called peeling electrification, which occurs when separating, it is possible to accurately evaluate the amount of static electricity.

Although the thickness of the insulating spacer 5, that is, the distance d between the lower surface of the substrate 1 and the ground plate 2 is 1 mm, the distance is set to the lower surface of the substrate 1 and the ground plate 2.
And the electrostatic capacitance Cd is between the electrostatic capacitance C of the substrate 1 itself.
By configuring so as to be larger than 1/10 of g, the difference in the charge amount between the front and the back can be detected with high sensitivity, and more accurate evaluation becomes possible. When Cd is smaller than this, the degree of influence of Q ₁ and Q ₂ on the measured surface potential becomes similar, and the difference between Q ₁ and Q ₂ cannot be represented by the difference between the front and back surface potentials. It is not preferable because the amount of charges on the back cannot be separated. That is, assuming that Cd = k · Cg, equations (2) and (3) are as follows.

[0045]

(Equation 8)

[0046]

[Equation 9]

For example, when k = 1/10, Q ₁
The weight of the influence on V ₁ and V ₂ is 11:10, that is, the influence on V ₁ is 10% greater than the influence on V ₂ .
For Q ₂ , the effect on V ₂ is 10% greater than the effect on V ₁ , and if this difference is detected, Q ₁ and Q ₂ can be distinguished from the measured values. On the other hand, when k = 1/50, for example, the difference between the respective weights becomes small at 2%, and the degree of influence of Q ₁ and Q ₂ on V ₁ and V ₂ is almost the same. ₁ , Q ₂
Becomes difficult to distinguish, and the error becomes large.

In this embodiment, the size of the substrate 1 is 300.
mm × 400 mm, its thickness was 1 mm, and the relative permittivity was 6, the Cg for that substrate was Cg = ε _o · ε _r / g (ε _o even when different substrates were used. Is the dielectric constant of the vacuum, ε _r is the relative dielectric constant of the substrate 1, and g is the thickness of the substrate 1). Further, an example in which a stainless steel plate is used as the ground plate 2 has been shown, but any other material may be used as long as it is a conductive material, and the material is not limited. Further, although the ground plate 2 is formed larger than the substrate 1 in the example shown in FIG. 1, the ground plate 2 may have the same size, or the ground plate 2 may be made small enough not to affect the measurement of the electric potential of the peripheral portion.

In this embodiment, since the substrate 1 is installed on the large ground plate 2 with the insulating spacer 5 interposed therebetween, the probe 3a of the surface electrometer 3 can be moved to a plurality of positions by moving the probe 3a at a certain gap. It is possible to measure the amount of electrostatic charge of, and to know its distribution status.

Embodiment 2 FIG. 2 is an explanatory diagram of a second embodiment of the electrostatic charge amount detecting device of the present invention. In the second embodiment, the mounting table on which the insulative substrate 1 is mounted is also used as a transporting unit constituted by, for example, a rotating roller 14, and the electrostatic charge amount on both sides of the substrate 1 can be detected while transporting. Is.

In FIG. 2A, reference numeral 10 denotes a first potential probe installed so as to face the upper surface of the substrate 1, and 11
Is a first ground plate installed on the side of the substrate 1 opposite to the first potential probe 10 in parallel with the substrate 1 with a constant gap. Reference numeral 12 denotes a second potential probe installed so as to face the lower surface of the substrate 1, 13 denotes a side opposite to the second potential probe 12 with respect to the substrate 1, parallel to the substrate 1,
The second installed with the same gap as the first ground plate 11
It is a ground plate. Reference numeral 14 is a roller which is a transporting means for transporting the substrate 1. The distance a between the first potential probe 10 and the upper surface of the substrate 1 and the distance a between the second potential probe 12 and the lower surface of the substrate 1 are both set to a = 3 mm, and the first ground plate 11 and the lower surface of the substrate 1 are separated from each other. Both the distance d and the distance d between the second ground plate 13 and the upper surface of the substrate 1 were set to d = 1 mm. That is, the first surface potential measuring means including the first ground plate 11 and the first potential probe 10, and the second surface potential measuring unit including the second ground plate 13 and the second potential probe 12.
The surface potential measuring means is provided in the opposite direction to the substrate 1. In addition, the first and second ground plates 11 and 13 are squares each having a width h of 20 mm.

First, the surface potential V ₁ of the upper surface of the substrate 1 is measured by the first potential probe 10 at one measurement point of the insulating substrate _1.
To measure. Next, the measurement point is the second potential probe 1
The insulative substrate 1 is moved on the roller 14 so as to be in a position facing 2 and the surface potential V ₂ of the lower surface of the substrate 1 at the measurement point is measured by the second potential probe 12.

According to this embodiment, the surface potentials of the upper and lower surfaces can be measured while the substrate 1 is being transported.
It is easy to measure the surface potentials on both the front and back surfaces of the substrate 1, and there is no charge leakage on the back surface of the substrate 1 and no new peeling charge that occurs when the conventional substrate 1 is removed from the ground plate that is the measuring stand. , It is possible to accurately evaluate the charge amount on both the front and back sides.

In this case, the length h of one side of the ground plates 11 and 13 is made larger than the distance b (= a + g + d) between the potential probes 10 and 12 and the ground plates 11 and 13 to contact the substrate 1. Since the capacitance between the ground planes 11 and 13 is accurately defined, it is possible to accurately determine the charge density from the potential measurement value. Therefore, the surface charge density can be accurately evaluated.

From the surface potentials V ₁ and V _{2 on} the front and back sides of the substrate 1 thus obtained, the formula (4) shown in Example 1 is used.
By applying, it is possible to obtain the charge density accumulated on each of the front and back surfaces of the substrate 1.

Further, according to the present embodiment, it is possible to detect the amount of electric charge charged during the transportation in the normal manufacturing process, and without requiring a special process, the cause of the occurrence of static electricity, its countermeasure, and It is possible to surely remove the generated charge accurately.

In the example described here, the device for measuring the potentials on both the front and back surfaces of the insulating substrate by the two pairs of potential probes and the ground plate is used, but three or more pairs of potential probes and the ground plate may be used. In that case, it becomes easier to measure the in-plane distribution of the surface potential of the insulating substrate 1. In particular, the first surface potential measuring means composed of the first potential probe 10 and the first ground plate 11 and the second surface potential measuring means composed of the second potential probe 12 and the second ground plate 13 are provided. , Fig. 2
As shown in (a), if a plurality of sets of surface potential measuring means provided along the substrate transport direction are provided in a direction perpendicular to the substrate transport direction, the surface potential of the insulating substrate 1 is within the plane. The distribution can be measured accurately and easily.

Embodiment 3 FIG. 3 is a diagram showing another embodiment of the electrostatic charge detecting device of the present invention. In FIG. 3, 20 is the potential measuring unit shown in Example 2, 21 is the potential obtained by the potential measuring unit,
It is an operation unit that is composed of a computer that calculates the amount of electric charge. The calculation means is composed of, for example, a general-purpose computer having an analog voltage input function.

The surface potentials V ₁ and V _{2 on} both the front and back surfaces of the substrate 1 are measured by the potential measuring unit 20, and these V ₁ and V ₂ are taken into the calculating means and based on the equation (4) shown in the first embodiment. The amount of electric charge on each of the front and back sides of the substrate 1 is calculated by the calculation means 2
1 is displayed on a display device (not shown) connected to the display device 1.

In the apparatus of the third embodiment, the charge amount is automatically calculated based on the measured potential, so that the charge amount can be known easily and directly.

[0061]

According to the electrostatic charge amount detecting method and the apparatus therefor of the present invention, the insulating substrate to be measured is arranged on the ground plate with a constant gap, and the surface potential is measured. The charges on the back side of the measurement surface hardly change, and the surface potentials on both sides can be measured by the same method to determine the charge amounts charged on both sides of the insulating substrate separately for the front and back sides.

Therefore, it is possible to properly perform static elimination for removing the generated static electricity, and it is easy to take a measure to prevent the generation of the static electricity. Can be prevented from becoming defective. As a result, the yield of electronic devices such as liquid crystal display devices can be improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an embodiment of an apparatus for detecting an electrostatic charge amount according to the present invention.

FIG. 2 is a diagram illustrating another embodiment of the apparatus for detecting the amount of electrostatic charge according to the present invention.

FIG. 3 is a diagram illustrating still another embodiment of the apparatus for detecting the amount of electrostatic charge according to the present invention.

FIG. 4 is a diagram illustrating a conventional device for detecting an electrostatic charge amount.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Ground plate 3 Surface potential meter 3a Potential probe 10 First potential probe 11 First ground plate 12 Second potential probe 13 Second ground plate 21 Computing means

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hirotaka Muto 1-1-1, Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation Central Research Institute (72) Inventor Hiroka Kitabayashi 8-1-1 Tsukaguchihonmachi, Amagasaki Mitsubishi Electric Central Research Institute, Inc. (72) Inventor Haruhisa Fujii 8-1-1 Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation Central Research Institute

Claims (10)

[Claims] 1. (a) A potential probe of a surface electrometer is provided on one surface side of an insulating substrate at a certain distance, and the substrate is provided on the other surface side of the substrate facing the potential probe. A ground plate is provided at regular intervals, and the potential V ₁ of the _one surface of the substrate is measured by the surface electrometer, (b)
The potential V ₂ on the other surface side of the substrate is measured by the same method as in (a), and (c) the capacitance per unit area of the air gap between the surface of the substrate and the ground plate is Cd, The capacitance per unit area of Cg, 1 / C = 1 / Cd +
As 1 / Cg, the electrostatic charge density Q ₁ on one surface side of the substrate and the electrostatic charge density Q ₂ on the other surface side of the substrate are expressed as follows. A method for detecting the amount of electrostatic charge on an insulating substrate, which is characterized by: 2. The electrostatic charge amount detection method according to claim 1, wherein the electrostatic charge amount is detected at a plurality of locations on the insulating substrate, and a distribution tendency of the electrostatic charge amount on the substrate surface is detected. 3. The substrate so that the capacitance per unit area formed by the gap between the substrate surface and the ground plate is 1/10 or more of the capacitance per unit area of the substrate itself. 3. The electrostatic charge amount detection method according to claim 1, wherein a gap with the ground plate is set. 4. A mounting table for partially supporting an insulating substrate for measuring an electrostatic charge amount, and a mounting table provided on one side of the substrate mounted on the mounting table so as to have a constant gap with the substrate. And a surface potential having a potential probe for measuring the potential of the surface of the substrate, the potential probe being provided on the other side of the substrate opposite to the one side of the substrate. An electrostatic charge detection device including a meter. 5. The electrostatic charge amount detecting device according to claim 4, further comprising calculation means for calculating an electrostatic charge amount on the surface of the substrate from a potential measured by the surface electrometer. 6. The electrostatic charge detection device according to claim 4, wherein the ground plate is made of a conductive plate material, and the mounting table is a spacer provided on the ground plate. 7. The mounting table is also used as a transport means for transporting the substrate in a direction parallel to the surface of the substrate, and the ground plate and the surface electrometer are respectively provided on both sides of the substrate transported by the transport means. A first surface potential measuring means composed of a first potential probe and a first ground plate of a surface electrometer provided so as to have a constant gap with the substrate; and a first probe and a first ground plate. A second probe including a second probe and a second ground plate of the surface electrometer, which are provided in the same manner as the first surface potential measuring means but have an opposite relationship to the substrate.
6. The electrostatic charge amount detecting device according to claim 4 or 5, further comprising a surface potential measuring means. 8. A set of surface potential measuring means formed by arranging the first and second surface potential measuring means along a direction in which the substrate is transported, and a set of surface potential measuring means for transporting the substrate. 8. The electrostatic charge amount detecting device according to claim 7, wherein a plurality of sets are provided in a direction perpendicular to the vertical direction. 9. The electrostatic charge amount detecting device according to claim 7, wherein the length of each side of the ground plate is formed to be larger than the distance between the ground plate and the potential probe facing the ground plate. 10. The capacitance per unit area formed by the gap between the ground plate side surface of the insulating substrate placed on the mounting table and the ground plate is equal to the capacitance per unit area of the substrate. The grounding plate is provided so as to have a capacitance of 1/10 or more of the capacitance.
The electrostatic charge detection device described.