JP3531890B2 - Surface potential measuring device, substrate processing device, and surface potential measuring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to measurement of a surface potential of a substrate such as a glass substrate for a liquid crystal display and a semiconductor wafer for an integrated circuit.

[0002]

2. Description of the Related Art When manufacturing an integrated circuit such as a liquid crystal display or an LSI, various processes are performed on a predetermined substrate. For example, when manufacturing a TFT active matrix type liquid crystal display, TF
2. Description of the Related Art In order to form an electrode portion of T (thin film transistor), a process of forming a thin film of amorphous silicon or the like on a glass substrate is performed.

In the processing of such a substrate, the surface of the substrate is charged, and this charging may cause a certain problem. The charging of the substrate may occur when gas discharge or the like is used for processing, but the main cause is a phenomenon called peeling charging. This is due to the fact that when separating different members that are in close contact with each other, a large amount of electrons remain on the surface of one member and electrons are deficient on the surface of the other member due to the difference in electron affinity between the two members. It is.

[0004] In many substrate processing apparatuses, an operation of transferring a substrate between an arm of a transfer robot and a substrate holder or the like is performed. Therefore, contact and separation between the substrate and different kinds of members are frequently performed. Therefore, the occurrence of the peeling charging is inevitable. Note that such charging of the substrate is not limited to a substrate made of a dielectric such as a glass substrate, but may also occur on a semiconductor or conductor substrate. This is because an insulating film may be formed on the surface of the substrate.

[0005] A serious problem in charging a substrate is that the voltage generated by charging varies with the movement of the substrate. This will be described with reference to FIG.
FIG. 9 is a diagram for explaining a point where the voltage of the charged substrate fluctuates due to the movement of the substrate. FIG. 9 partially shows a substrate processing apparatus for processing the substrate 2 by disposing the substrate 2 in the vacuum vessel 1.

In most cases, the vacuum vessel 1 is grounded and kept at a ground potential. Therefore, when the substrate 2 in the vacuum vessel 1 is charged, a potential difference is generated between the substrate 2 and the wall 10 of the vacuum vessel 1, and a voltage is generated. This voltage V is generated by the charge Q induced on the surface of the substrate 2 as is well known, and the relationship Q = CV is established. This C is the capacitance of the space between the substrate 2 and the container wall 10.

Here, since C = εS / d, the substrate 2
When the distance d between the device and the container wall 10 changes, the capacitance C also changes. On the other hand, the charge Q on the surface of the substrate 2 is constant and does not change. That is, the charge Q is stored regardless of the change in the capacitance C. Therefore, when the substrate 2 moves and the distance from the container wall 10 changes as d ₁ → d _{2 and} the capacitance changes from C ₁ to C ₂ , Q = C ₁ V ₁ = C ₂ V ₂ = voltage to be constant is changed from V ₁ to V _2. Furthermore, d ₂ → d ₃
, The voltage V increases to satisfy the above-mentioned Q = CV. At this time, if there is a place where the electric field is concentrated due to a projection or the like on the surface of the container wall 10, discharge may occur at that place. When the discharge occurs, a large current flows from the substrate 2 to the ground of the container wall 10, and a circuit or an element formed on the substrate 2 may be broken by the current.

However, the above-described discharge is unlikely to occur in a vacuum, and the discharge rarely occurs inside the vacuum vessel 1. The generation of a high voltage due to the movement of the substrate 2 poses a major problem in that discharge within the substrate 2 is caused. That is, when the voltage generated by the charging of the surface of the substrate 2 increases, a large dielectric polarization occurs in the substrate 2,
A dielectric breakdown occurs in the substrate 2 to generate a discharge. As a result,
A large discharge current flows in the substrate 2 and damages circuits and elements. In the atmosphere, since the surface charge of the substrate 2 is neutralized by ionized gas molecules slightly present in the atmosphere, such a problem of the charging of the substrate 2 is not so serious. However, it is a serious problem in a vacuum.

In consideration of the above, in the substrate processing apparatus which handles the substrate 2 which may be charged, the material of the surface of the substrate holder or the like is selected so that the charging of the substrate 2 is minimized, or the charging is performed. Even if it does, the dimension and shape of the structure in the vacuum vessel 1 are designed so that the voltage does not increase so much depending on the movement of the substrate 2. However, what is necessary for such selection and design is to confirm how much charge is actually generated on the substrate 2, that is, to measure the surface potential of the substrate 2. .

According to an investigation by the inventor, no practical device capable of measuring the surface potential of the substrate 2 is commercially available. The only experimental device is shown in FIG.
2. Description of the Related Art An apparatus as shown in FIG. FIG.
FIG. 7 is a schematic cross-sectional view illustrating a configuration of a conventional surface potential measurement. The conventional surface potential measuring apparatus shown in FIG. 10 utilizes a piezo effect, and includes a piezo element 3 arranged opposite to a substrate 2 to be measured, and a piezo element for detecting the magnitude of dielectric polarization of the piezo element 3. It comprises a piezo electrode plate 4 provided on the back surface of the element 3, a chopper 5 for periodically shielding an electric field E between the substrate 2 and the piezo element 3, and the like.
Further, the piezo element 3 is provided with a pressing mechanism (not shown) that presses the side surface to apply external stress in a direction perpendicular to the direction of the electric field E between the piezo electrode plate 4 and the substrate 2. .

In FIG. 10, assuming that the distance d between the piezo element 3 and the substrate 2 is known, a voltage of V = dE is applied to the piezo element 3 by an electric field E between the piezo electrode plate 4 and the substrate 2. You. As a result, the electric charge appearing on the piezo electrode plate 4 is equal to the electric charge due to the piezo effect (lateral piezo effect) and the voltage V.
And the charge due to Here, chopper 5
Is used to periodically cut off the electric field E and extract the electric charge appearing on the piezo electrode plate 4 as an electric signal by an appropriate method, the electric signal changes periodically in synchronization with the cycle of the chopper 5. I do. It is clear that the magnitude of the change depends on the surface potential of the substrate 2, and the surface potential of the substrate 2 can be measured by knowing the magnitude of the change.

[0012]

However, as described above, the above-mentioned apparatus is an experimental apparatus, and its practicality is considerably low.
In particular, an apparatus for measuring the surface potential of a substrate processed in a vacuum as described above has the following fatal defects. That is, first of all, a high-speed driving mechanism such as a chopper inevitably generates dust due to evaporation and abrasion of a lubricant or the like, and arranging such a component in a vacuum maintains a necessary vacuum pressure. In addition to having a serious adverse effect on the substrate, dust may adhere to the surface of the substrate and become dirty, causing serious damage such as circuit failure. When a piezo element is used, wiring for extracting an electric signal is indispensable as described above. On the other hand, a corrosive gas such as a fluorine-based gas may be used for the processing of the substrate, and the wiring used for the piezo element is severely corroded by the corrosive gas and cannot be used. As described above, there is no surface potential measuring device or surface potential measuring method suitably used for a substrate processing apparatus that performs processing in a vacuum, and the inventor considered that the development is urgent.

[0013]

According to an aspect of the present invention, there is provided a surface potential measuring apparatus for measuring a surface potential of a substrate disposed in a vacuum, comprising:
A conductor plate arranged opposite to the substrate with a predetermined gap in a deformable or displaceable state, and the magnitude of the deformation or displacement of the conductor plate caused by the Coulomb force acting between the substrate and the conductor plate. a detecting means for detecting that, and a calculation means for calculating the surface potential of the substrate on the basis of the detection result of the detection means possess, before
The pressure in the gap between the substrate and the conductor plate is determined by the position of the substrate.
Is the vacuum pressure of the space defined, and
A container surrounding the space opposite to the side where the plate is
Vignetting is, the pressure in the vessel was f _1, the substrate
Ku but the vacuum pressure of the deployed space and f _2, measured
When the Ron force is F, f ₁ and f ₂ are both greater than F
Or the difference between f ₁ and f ₂ is sufficiently smaller than F
Small . Similarly, in order to solve the above problem, the invention according to claim 2 measures a surface potential of a substrate placed in a vacuum.
Surface potential measuring device that can be deformed or displaced
Conductor facing the substrate with a predetermined gap in the state
Plate and the Coulomb force acting between the substrate and the conductive plate.
To detect the magnitude of deformation or displacement of the conductor plate
Means and the surface potential of the substrate based on the detection result of the detecting means.
And a calculating means for calculating the closed space, wherein the space on the opposite side to the side of the conductor plate facing the substrate is a closed space.
Is provided, the interior of the sealed container is maintained at high vacuum pressures below ^10-5 Pa. Similarly above
In order to solve the problem, the invention according to claim 3 is applied to a vacuum.
Surface potential measuring device that measures the surface potential of the placed substrate
Having a predetermined gap in a deformable or displaceable state.
A conductive plate disposed opposite the substrate, and the substrate and the conductive plate
Deformation of Conductive Plate Caused by Coulomb Force Acting between
Or, detecting means for detecting the magnitude of the displacement, and detecting the detecting means
Calculating means for calculating the surface potential of the substrate based on the output result;
Having a pressure in a gap between the substrate and the conductor plate,
The vacuum pressure in the space where the substrate is placed,
Surrounding the space on the side opposite to the side where the substrate is placed
Container is provided, and the pressure in the container is vacuum.
Therefore, the pressure is the same as the vacuum pressure in the space in which the substrate is disposed.
You. Similarly, in order to solve the above problem, according to a fourth aspect of the present invention, in the configuration of the third aspect , the container is provided with an opening for communicating with a space in which the substrate is arranged. Similarly, in order to solve the above problem, in the invention according to claim 5 , in the configuration according to any one of claims 1 to 4 , the distance between the conductor plate and the substrate is variable. Similarly, in order to solve the above problem, in the invention according to claim 6, in the configuration according to any one of claims 1 to 5 , the detecting means faces the conductor plate on a side opposite to the side of the conductor plate facing the substrate. And a capacitance meter for detecting a change in capacitance between the conductor plate and the electrode plate caused by deformation or displacement of the conductor plate. Similarly, in order to solve the above-mentioned problem, the invention according to claim 7 is based on claim 1.
In any one of the constitutions ( 5) to (5) , the detecting means is such that a long magnet provided on the conductor plate so as to extend on a side opposite to the side of the conductor plate facing the substrate and a line of magnetic force of the long magnet interlink. And a current meter for detecting an induced current generated in the coil when the long magnet is displaced by the deformation or displacement of the conductor plate. Similarly, in order to solve the above problem, an invention according to claim 8 is a substrate processing apparatus for performing a predetermined process by arranging a substrate in a vacuum vessel provided with an exhaust system . It has a configuration that includes a surface potential measuring apparatus according to. Similarly, in order to solve the above-mentioned problem, an invention according to claim 9 is a substrate processing apparatus that performs a predetermined process by arranging a substrate in a vacuum vessel provided with an exhaust system. comprising a measuring device, further, the exhaust system, the vacuum chamber 10
^It has a structure capable of evacuating to a high vacuum at a pressure of ^-3 Pa or less. Similarly, in order to solve the above problem, the invention according to claim 10 is directed to a substrate disposed in a vacuum.
Surface potential measuring method for measuring the surface potential of
Or facing the substrate with a predetermined gap in a displaceable state
A conductor plate, and a cooler acting between the substrate and the conductor plate.
The magnitude of the deformation or displacement of the conductor plate caused by the
Detected by the detection means and based on the detection result of the detection means
This is a method of calculating the surface potential of the substrate by the calculating means.
The pressure in the gap between the substrate and the conductor plate is
Is the vacuum pressure of the space in which the
The pressure in the space on the side opposite to the side where the substrate is
It is the same as the vacuum pressure in the space where the substrate is arranged.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described. 1 and 2 are diagrams illustrating a first embodiment of the surface potential measuring device according to the present invention. Among them, FIG. 1 is a diagram for explaining an arrangement state of the surface potential measuring device,
FIG. 2 is a schematic front sectional view illustrating details of the surface potential measuring device. As shown in FIG. 1, the surface potential measuring device 100 according to the present embodiment is disposed so as to be fitted into a vessel wall 10 of a vacuum vessel 1 provided with an exhaust system 101. This arrangement position is a position facing the substrate 2 located at a predetermined position in the vacuum vessel 1.

As shown in FIG. 2, the surface potential measuring device includes a conductor plate 6 which is disposed opposite to the substrate 2 with a predetermined gap in a deformable or displaceable state; 6
Detecting means 7 for detecting the magnitude of the deformation or displacement of the conductive plate 6 caused by the Coulomb force acting between them, and calculating means 8 for calculating the surface potential of the substrate 2 based on the detection result of the detecting means 7. Have.

The vessel 10 of the vacuum vessel 1 has a closed vessel 91
Is fitted. The sealed container 91 has a front opening on a surface facing the substrate 2, and the conductor plate 6 is provided so as to airtightly close the front opening. The conductor plate 6 is a thin metal plate having a thickness of, for example, about 10 ⁻² mm, and can be deformed or displaced in a direction perpendicular to the plate surface. As the material of the conductive plate 6, for example, a corrosion-resistant NiCr alloy or the like can be adopted.

The detecting means 7 is located behind the conductor plate 6, that is, the substrate 2
An electrode plate 71 provided on the opposite side to the conductor plate 6 on the opposite side to the conductor plate 6, and changes the capacitance between the conductor plate 6 and the electrode plate 71 caused by deformation or displacement of the conductor plate 6. It mainly comprises a capacity meter 72 to be detected. Electrode plate 71
Are arranged in parallel with the conductor plate 6 with a predetermined gap. The capacitance meter 72 applies a constant voltage V between the electrode plate 71 and the conductor plate 6 to charge a capacitor composed of the electrode plate 71 and the conductor plate 6, and
1 and the conductor plate 6 were short-circuited to measure the current flowing when the capacitor was discharged, and the stored charge Q was measured.
It is configured to detect the capacitance C from the equation of C = Q / V. The conductor plate 6 and the electrode plate 71 have substantially the same dimensions and shape, for example, a circle having a diameter of about 75 mm. The gap between the conductor plate 6 and the electrode plate 71 is set to, for example, about 10 ^-1 mm.

In the first embodiment, the interior of the sealed container 91 is evacuated to a high vacuum of, for example, about 10 ^-5 Pascal and hermetically closed. Further, the inner surface of the sealed container 91 is coated with a getter material such as titanium, and adsorbs gas released from the inner surface to prevent a rise in internal pressure over time. The portion where the conductor plate 6 is closed to close the front opening and the portion where the wiring of the capacitance meter 72 penetrates the container are hermetically sealed.

The calculating means 8 comprises an input section to which the measurement result of the capacitance meter 72 is inputted, an arithmetic section for calculating the surface potential of the substrate 2 from the input of the input section according to a formula stored in advance in a ROM or the like. It is. The calculating means 8 includes a display unit (not shown) for displaying the calculated surface potential.

Next, the operation of the surface potential measuring device of the present embodiment having the above-described configuration will be described. First, the substrate 2 is arranged at a position facing the surface measuring device using an appropriate holder. The distance between the substrate 2 and the conductive plate 6 is, for example, about 47 mm. A constant voltage of, for example, 1000 V is applied to the electrode plate 71, and the capacitor formed by the electrode plate 71 and the conductor plate 6 is charged by this voltage. The conductor plate 6 is grounded and is at the ground potential.

In this state, if the substrate 2 is charged and a surface potential is present, the surface potential of the substrate 2 and the potential of the conductive plate 6 (=
0V), an electric field is generated, and the substrate 2 and the electrode plate 7
1 and the Coulomb force F acts. This Coulomb force F
Is represented by the following formula: F = (εV ² ) / (2d ² ) (unit: N / m ² ). Here, ε is the dielectric constant of vacuum, V is the potential difference, the distance between the d substrate 2 and the conductor plate 6, N
Is Newton and m is meters. The Coulomb force F deforms or displaces the conductor plate 6, and the magnitude of the deformation or displacement is detected by the detecting means 7.

With respect to the deformation or displacement of the conductor plate 6, FIG.
This will be supplementarily explained using. FIG. 3 is an explanatory diagram of deformation or displacement of the conductor plate 6. The conductor plate 6 is deformed or displaced by the Coulomb force between the conductive plate 6 and the charged substrate 2, and some forms of the deformation or displacement can be considered. First, when the conductor plate 6 is disposed with both ends fixed, as shown in FIG. 3A, the conductor plate 6 is deformed into an arc-shaped cross section. Further, in the case where elastic members 61 such as elastic bodies are provided at both ends of the conductor plate 6, as shown in FIG.
Is displaced in a direction perpendicular to the plate surface. Furthermore, when only one end of the conductor plate 6 is fixed, as shown in FIG. 3C, the conductor plate 6 is inclined (deformed).

Whether the state of the conductor plate 6 is “deformation”, “displacement”, or both may not be determined in some cases. The capacitance C between the conductive plate 6 and the conductive plate 6 changes. The value of the changed capacitance is measured by the capacitance meter 72. Then, the calculating means 8 calculates the magnitude of the deformation or displacement from the measured value of the capacitance, and further obtains the surface potential of the substrate 2 based on the calculation result.

More specifically, when the conductor plate 6 is displaced, for example, as shown in FIG.
Is calculated by the following equation: δ = d ₀ −d ₁ = εS / C ₀ −εS / C ₁ However, d ₀ is the conductor plate 6 in a state where the substrate 2 is not disposed (or the surface potential is 0 V, the same applies hereinafter).
The distance between the electrode plates 71, the distance between d ₁ is conductive plate 6 and the electrode plate 71 when displaced by the charging of the substrate 2, S is the size of the conductive plate 6 and the electrode plates 71, C ₀ is the substrate 2 the capacitance of the health state or the substrate 2 is not arranged is not charged, C ₁ represents the capacitance changes due to the arrangement of the charged substrate 2, respectively. The Coulomb force F required to generate the magnitude of displacement δ can be obtained by calculation from the mass of the conductive plate 6, the spring constant of the elastic body provided at both ends of the conductive plate 6, and the like. The surface potential of the substrate 2 is calculated according to the above-described equation (1).

The structure of the conductor plate 6, the sealed container 91, the electrode plate 71 and the detecting means 7 in the apparatus of the first embodiment is the same as that of a commercially available capacitance manometer (diaphragm gauge) for measuring vacuum pressure. Similar ones can be employed.
For example, a configuration such as Baratron 223BD manufactured by MKS is suitable. However, if this is used as it is, it does not become a surface potential measuring device, and it is necessary to add at least the configuration of the calculating means 8 described above.

Next, a second embodiment of the surface potential measuring device of the present invention will be described. FIG. 4 is a schematic front sectional view illustrating details of the surface potential measuring device according to the second embodiment. The surface potential measuring device shown in FIG. 4 is arranged so as to be fitted to the vessel wall 10 of the vacuum vessel 1 so as to face the substrate 2 as in the first embodiment. Then, as in the first embodiment, the conductor plate 6 disposed opposite to the substrate 2 with a predetermined gap in a deformable or displaceable state,
Detecting means 7 for detecting the magnitude of deformation or displacement of conductor plate 6 caused by the Coulomb force acting between it and conductor plate 6
And a calculating means 8 for calculating the surface potential of the substrate 2 based on the detection result of the detecting means 7.

In the device of the second embodiment, the structure of the detecting means 7 is greatly different from that of the first embodiment. That is, the detecting means 7 in the second embodiment includes a long magnet 73 provided on the conductor plate 6 so as to extend on the side opposite to the side of the conductor plate 6 facing the substrate 2, 7
Coil 74 arranged so that the three magnetic lines of force interlink
And an ammeter 7 for detecting an induced current generated in the coil 74 by the displacement of the long magnet 73 due to the deformation or displacement of the conductor plate 6.
5.

The long magnet 73 is a needle-like permanent magnet having a thickness of about 0.1 mm in diameter, and is vertically fixed to the center of the back surface of the conductive plate 6 by welding or the like. The coil 74 is disposed so that the lines of magnetic force coming out of the long magnet 73 interlink. Specifically, the coil 74 is disposed so that the longitudinal direction of the long magnet 73 coincides with the axis of the coil 74. I have.

In the above configuration, as in the first embodiment, when the conductor plate 6 is deformed or displaced by the Coulomb force generated by charging the substrate 2, the long magnet 73 is displaced in the longitudinal direction, and The intersecting lines of magnetic force change. As a result, an induced current flows through the coil 74, and this current is detected by the ammeter 75. The magnitude of the deformation or displacement of the conductive plate 6 is proportional to the Coulomb force, and the magnitude of the Coulomb force is proportional to the potential of the substrate 2. Since the magnitude of the deformation or displacement of the conductive plate 6 can be determined by the value of the induced current, as a result,
The potential of the substrate 2 is calculated.

For example, when the conductor plate 6 is deformed by the Coulomb force F as shown in FIG. 3A, the deformation (warpage) δ at the center of the conductor plate 6 is δ = δ3 ( M ² -1) Fr ⁴ ｝ / (16EM ² t ³ ) ... Equation (3) Where 1 / M is the Poisson's ratio of the conductor plate 6,
r is the radius of the conductor plate 6, E is the Young's modulus of the conductor plate 6, and t is the thickness of the conductor plate 6. Therefore, δ is determined according to the magnitude of the induced current, and is substituted into the above equation to determine the Coulomb force F. Then, if V is calculated by substituting into the aforementioned equation (1), the potential of the substrate 2 is finally calculated.

In order to confirm the effectiveness of the devices of the above embodiments, the inventor conducted a simulation experiment. That is, a predetermined power supply was connected to the substrate 2 to apply a surface potential of 1000 V, and in this state, the surface potential measuring devices having the above-described configurations were operated, and it was confirmed whether or not a measurement result according to theoretical calculation was obtained. First,
In the device according to the first embodiment, the substrate 2 and the conductive plate 6
Is 47 mm, and the distance between the electrode plate 71 and the conductor plate 6 (d
₀ ) was 0.1 mm. The deformation or displacement of the conductor plate 6 was the pattern shown in FIG. Therefore, the amount of deformation of the conductor plate 6 complies with the above-mentioned equation (3).

When the substrate 2 is not disposed, the displacement of the conductor plate 6 does not occur, and the capacitance of the capacitor formed by the conductor plate 6 and the electrode plate 71 is calculated by the above-described equations (1) and (2).
Is calculated to be 391.6 pF. When the surface potential of the substrate 2 is 1000 V, the conductive plate 6 is warped and deformed by δ = 14.1 μm from the equation (3).
The capacitance at this time is 342.7 pF, and 48.9 pF
The change in F should be measured.

On the other hand, when the output of the capacitance meter 72 was actually observed, the capacitance when the surface potential of the substrate 2 was 0 V was approximately 391.6 pF, and the capacitance when the surface potential was 1000 V was applied. The capacity is 357.7 pF and 40.8 pF
The change in F was measured. From this result, a measurement error of 20%
It was found that the surface potential can be measured with a degree of accuracy.

In the apparatus according to the second embodiment, the distance between the substrate 2 and the conductive plate 6 is set to 47 mm.
In the theoretical calculation, when a surface potential of 1000 V is applied to the substrate 2, the amount of warpage δ of the conductive plate 6 is similarly 14.1 μm. On the other hand, when a surface potential of 1000 V is actually given,
The amount of warpage calculated from the induced current detected by the detection means 7 was approximately 13 μm. Therefore, in this embodiment, it was found that the measurement could be performed with an accuracy of about 8%.

Next, the problem of the measurement range of the device according to each of the above embodiments will be described. FIG. 5 is a diagram illustrating a measurement range of the device shown in FIG. 2 or FIG. As described above, the conductor plate 6 in each of the above embodiments is provided so as to hermetically close the front opening of the sealed container 91, and the space behind the conductor plate 6 is a sealed space maintained at a high vacuum. ing. In this case, the pressure in front of the space or arranged space of the substrate 2 of the conductive plate 6, a force is applied coming from the pressure differential across the conductive plate 6, guide by the force
The body plate 6 is expected to undergo the deformation or displacement as described above.

Here, as shown in FIG. 5, the pressure inside the closed vessel 91 of the surface potential measuring device (the pressure behind the conductor plate 6) is f ₁ , and the pressure inside the space where the substrate 2 is arranged (the conductor plate) is 6
Assuming that the pressure in front of f) is f ₂ and the Coulomb force is F, measurement with sufficient accuracy is possible if any of the following relationships A and B is established. _{A: F "f 1, f} 2 B: f = f 1 -f 2" F that is, whether f ₁ and f ₂ is sufficiently smaller than the F, f ₁
If the magnitude of −f ₂ is sufficiently smaller than F, the magnitude of the deformation or displacement due to the pressure difference can be ignored compared to the magnitude of the deformation or displacement due to the Coulomb force.

Here, in each of the above-described embodiments, the inside of the sealed container 91 is maintained at a high vacuum of 10 ⁻⁵ Pa or less. That is, in the above embodiments, F "f ₁ is first achieved. Therefore, if the pressure in the space where the substrate 2 is disposed is set to a high vacuum of 10 ⁻³ Pa or less, F >> f ₂
Is achieved, and measurement with sufficient accuracy becomes possible.
In this case, the difference between _{f 1} and _{f 2} (pressure difference) is not necessary to adjust the _{f 2} to be smaller. That is, in the configuration of each of the above embodiments, the condition of A is automatically achieved and high-precision measurement is possible as long as the space in which the substrate 2 is arranged is maintained at a high vacuum of 10 ⁻³ Pa or less. It becomes. Many substrate processing apparatuses using a vacuum such as a chemical vapor deposition (CVD) apparatus are provided with a high vacuum exhaust system such as a turbo molecular pump or a cryopump. Such a substrate processing apparatus can be used without requiring any change.

On the other hand, if the inside of the sealed container 91 is not at a high vacuum as described above, it is difficult to satisfy the condition A, and the space in which the substrate 2 is arranged so as to satisfy the condition B is used. The pressure must be adjusted. For example,
When the inside of the closed container 91 is 100 Pascal, the pressure in the space in which the substrate 2 is arranged is 99.99999 to 109.99
It must be adjusted to the range of 0.0001 Pascal. However, it is very difficult to maintain a constant vacuum pressure with six significant figures, and a configuration in which the inside of the sealed container 91 is not a high vacuum is not very practical.

The pressure in the space where the substrate 2 is arranged is
If for some reason the high vacuum cannot be achieved, condition A,
It is difficult to satisfy any of B. The third embodiment described below is effective in the case where the substrate 2 is placed in such a pressure range from a medium vacuum to a low vacuum for measurement. FIG. 6 is a schematic front cross-sectional view illustrating details of the surface potential measuring device according to the third embodiment of the present invention. Less than
Is a description of the embodiment of the invention of the surface potential measuring method.
There is also.

The apparatus shown in FIG. 6 is the same as that shown in FIG.
Is different from the device shown in FIG.
There is not a closed vessel, is that the opening 90 is provided. As can be seen from FIG. 6, the opening 90 is provided so as to allow the space in which the substrate 2 is arranged to communicate with the inside of the container 92. That is, the pressure in the container 92 and the pressure in the space in which the substrate 2 is arranged are equalized by the opening 90. In the embodiment shown in FIG. 6, the above-mentioned f1 and f2 are equal, and the condition B is achieved by a simple configuration in which the container 92 is not a closed container and the opening 90 is provided.
For this reason, it is possible to perform highly accurate measurement not only when the pressure in the space where the substrate 2 is disposed is high vacuum but also in a pressure range from medium vacuum to low vacuum. The size of the opening 90 may be, for example, about 1 mm in diameter. Further, the space in the container 92 and the space in which the substrate 2 is arranged may not be directly communicated by the opening 90. That is, the communication may be established by a bypass pipe or the like connected to the opening 90.

[0041] Incidentally, considering only that f ₁ and f ₂ may be equal, it is possible to measure in principle even atmospheric pressure. However, the thin conductor plate 6 having a thickness of, for example, about 10 ⁻² mm is deformed or displaced by warpage or the like due to the presence of a slight air current of a gentle breeze, and this is included in the measured values. I will. Therefore, it is preferable that the measurement is performed with the substrate 2 placed in a vacuum, that is, a pressure lower than the atmospheric pressure.

In the above configuration, when a highly corrosive gas is present at the place where the substrate 2 is disposed, the gas enters the container 92 through the opening 90. Therefore, in the embodiment of FIG. 6, a member having no corrosion resistance should not be provided in the container. Conversely, the device of the first and second embodiments described above is superior to the third embodiment in that such restrictions are not imposed.

Next, a fourth embodiment of the present invention will be described. FIG. 7 is a schematic front sectional view of the surface potential measuring device according to the fourth embodiment. The device of the fourth embodiment differs from the device of the third embodiment in that the distance between the substrate 2 and the conductor plate 6 is variable. Specifically, one end of a bellows 93 is provided around the periphery of the opening for the surface potential measuring device provided on the vessel wall 10 of the vacuum vessel 1 and extends inside the vacuum vessel 1, and the other end of the bellows 93 is provided. Is fixed to a container 92 of the surface potential measuring device.

The container 92 is provided with a holding arm 94 holding the container 92 and a holding arm 94 via the holding arm 94.
A drive mechanism 95 or the like for moving the container up and down is provided, and the container 92 moves up and down by these configurations, whereby the distance between the substrate 2 and the conductor plate 6 is variably configured. Substrate 2
Changing the distance between the conductor and the conductor plate 6 is determined by the above-described equation (1).
As can be seen from FIG. 5, the range of the surface potential to be measured can be adjusted. Therefore, the configuration of the apparatus of the embodiment shown in FIG. 7 has an advantage that the surface potential of the substrate 2 can be measured over a wide range. It is needless to say that the distance between the substrate 2 and the conductor plate 6 can be made variable by the same configuration in the device of the first or second embodiment.

Next, an embodiment of the invention of a substrate processing apparatus equipped with the surface potential measuring device of the present invention will be described.
FIG. 8 is a schematic front sectional view for explaining an embodiment of the invention of the substrate processing apparatus equipped with the surface potential measuring device. The above-mentioned surface potential measuring device is suitably used when selecting the material of the surface of the arm of the transfer robot or the substrate holder and designing the details of the substrate processing apparatus such as the dimensions and shape of the vacuum vessel.
That is, an apparatus is prototyped based on a certain design, a substrate is carried into the prototype, a predetermined operation is performed, and whether or not the substrate is charged is measured.

In this case, it is conceivable to take out the substrate 2 from the apparatus and carry it into another vacuum vessel 1 as shown in FIG. 1 to measure the surface potential. However, the substrate processing apparatus itself has a surface potential measuring function. It is very convenient to give it. It is very preferable that the surface potential measurement function is provided in a normal practical machine, even if it is not a prototype machine, because the surface potential of the substrate can be monitored at any time during processing or the like. The apparatus shown in FIG. 8 is configured in consideration of such points, and is a substrate processing apparatus having a surface potential measuring function.

The apparatus shown in FIG. 8 is configured to perform a plasma CVD process as an example of a substrate process. That is, a vacuum vessel 1 having an exhaust system 101 and a substrate holder 1 for disposing a substrate 2 at a predetermined position in the vacuum vessel 1.
02, a gas introduction means 103 for introducing a predetermined reactive gas into the vacuum vessel 1, and a high frequency supplied to a coil wound around a dielectric vessel such as a bell jar to supply energy to the internal gas. And plasma forming means 104 for forming plasma.

In the apparatus shown in FIG. 8, the introduced gas causes a gas phase reaction such as decomposition by plasma, whereby a predetermined thin film is deposited on the surface of the substrate 2. For example, when depositing a thin film of amorphous silicon, a mixed gas of monosilane and hydrogen is introduced to form plasma, and the amorphous silicon thin film is deposited by decomposition of monosilane.

In the apparatus shown in FIG. 8, the surface potential measuring apparatus 100 is, like the case shown in FIG.
It is arranged so as to be fitted in. That is, an opening for a surface measuring device is provided in the container wall 10 of the vacuum vessel 1, and the closed container 91 described above is provided in the opening for the surface measuring device.
(Or the container 92), the surface potential measuring device 100 is provided.

In the apparatus of this embodiment, a bell jar constituting the plasma forming means 104 is provided at a position facing the substrate 2 placed on the substrate holder 102. 100 cannot be disposed, and is disposed at a position slightly shifted from the substrate holder 102. Therefore, when operating the surface potential measuring device 100, the substrate 2 is moved to a position facing the surface potential measuring device 100 using a transfer robot or the like that can operate in a vacuum, and measurement is performed while maintaining this position. To do. At this time, as described above, by setting the inside of the vacuum vessel 1 to 10 ^-3 Pa or less using the exhaust system 101, highly accurate measurement can be performed.

In the configuration of each embodiment of the present invention described above, the configuration of the detecting means 7 for detecting the magnitude of the deformation or displacement of the conductor plate 6 may be variously considered in addition to the above. For example, a configuration in which a laser displacement meter is used to optically detect the displacement or a displacement of a cantilever that moves in conjunction with the deformation of the conductive plate 6 can be adopted. Further, the substrate 2 and the conductor plate 6 need not be parallel, and may be inclined. In the case of inclination, the equation for obtaining the Coulomb force is only complicated, and is sufficiently practicable. Further, for the same purpose, the conductor plate 6 and the electrode plate 71 in the first embodiment need not be parallel. Although it is not included in the scope of the present invention, it will be apparent from the above description that there is no problem in principle even if the object for measuring the surface potential is not a substrate, that is, a plate-like object.

[0052]

As described above, claim 1 of the present application
According to the invention of 2, 3, 6 or 7 , a practical device for measuring the surface potential of the substrate is provided. In particular, since it is not necessary to employ a high-speed driving mechanism such as a chopper unlike a conventional apparatus, the apparatus is very suitable as an apparatus for measuring the surface potential of a substrate placed in a vacuum. Claim 2
According to the invention, particularly, the space behind the conductor plate is 10 ^−5.
Since the vacuum is maintained at a high vacuum equal to or lower than Pascal, high-precision measurement is possible only by setting the space in which the substrate is placed to a high vacuum, and the apparatus is very easy to use. Claim 4
According to the invention, in addition to the above effects, the container surrounding the space behind the conductor plate is provided with the opening communicating with the space in which the substrate is disposed, so that the space in the container and the space in which the substrate is disposed are separated. The same pressure is automatically set, and as a result, highly accurate measurement can be easily performed even in a low vacuum to medium vacuum pressure region. According to the invention of claim 5 , in addition to the above effects, the distance between the conductor plate and the substrate is variable, so that the measurement can be performed in a wide range of surface potential. There is. According to the eighth aspect of the present invention, there is provided a substrate processing apparatus having a surface potential measuring function having the above effect. Further, according to the ninth aspect of the present invention, there is provided a substrate processing apparatus capable of easily performing a highly accurate measurement of a surface potential. According to the tenth aspect,
A practical method for measuring the surface potential of a substrate is provided.
In particular, a high-speed drive mechanism such as a chopper is adopted as in the past.
Surface of the substrate placed in a vacuum because it is not necessary to use
This is a very suitable method for measuring the potential.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first embodiment of a surface potential measuring device according to the present invention, and is a diagram illustrating an arrangement state of the surface potential measuring device.

FIG. 2 is a diagram illustrating a first embodiment of the surface potential measuring device of the present invention, and is a schematic front sectional view illustrating details of the surface potential measuring device.

FIG. 3 is an explanatory diagram of deformation or displacement of a conductive plate.

FIG. 4 is a schematic front sectional view illustrating details of a surface potential measuring device according to a second embodiment.

FIG. 5 is a diagram illustrating a measurement range of the device shown in FIG. 2 or FIG.

FIG. 6 is a schematic front sectional view illustrating details of a surface potential measuring device according to a third embodiment of the present invention.

FIG. 7 is a schematic front sectional view of a surface potential measuring device according to a fourth embodiment.

FIG. 8 is a schematic front sectional view illustrating an embodiment of the invention of a substrate processing apparatus equipped with a surface potential measuring device.

FIG. 9 is a diagram illustrating a point where the voltage of a charged substrate changes due to movement of the substrate.

FIG. 10 is a schematic sectional view illustrating a configuration of a conventional surface potential measurement.

[Explanation of symbols]

1 vacuum container 10 Wall 2 Substrate 6 conductor plate 7 Detecting means 71 Electrode plate 72 capacity meter 73 long magnet 74 coil 75 ammeter 8 Calculation means 90 opening 91 Closed container 92 containers 93 Bellows 94 Holding arm 95 Drive mechanism 100 Surface potential measuring device 101 Exhaust system

Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01R 29/12 G01R 29/24 H01L 21/66

Claims (10)

(57) [Claims] 1. A surface potential measuring device for measuring a surface potential of a substrate placed in a vacuum, wherein the conductor plate is disposed to face the substrate with a predetermined gap in a deformable or displaceable state. Detecting means for detecting the magnitude of deformation or displacement of the conductive plate caused by Coulomb force acting between the substrate and the conductive plate, and calculating means for calculating the surface potential of the substrate based on the detection result of the detecting means It has a pressure of the gap between the substrate and the conductive plate, the substrate distribution
Vacuum pressure of the space in which the
A container surrounding the space opposite to the side where the substrate is placed
Is provided, the pressure in the vessel was f _1, wherein the substrate is placed empty
The vacuum pressure between is f ₂ and the Coulomb force to be measured is F
, When both f ₁ and f ₂ are sufficiently smaller than F
Or, the surface potential measuring apparatus difference f ₁ and f ₂ is equal to or sufficiently smaller than the F. 2. A method for measuring a surface potential of a substrate placed in a vacuum.
Surface potential measuring device that can be deformed or displaced
In this state, a conductor is placed facing the substrate with a predetermined gap.
The Coulomb force acting between the body plate and the substrate and conductor plate
Detection of the magnitude of deformation or displacement of the conductor plate caused by
Output means and the surface voltage of the substrate based on the detection result of the detection means.
And a calculating means for calculating the position, wherein a closed container is provided in which a space opposite to the side of the conductor plate facing the substrate is a closed space, and the inside of the closed container is 10 ⁻⁵ Pascal. A surface potential measuring device characterized by being maintained in a high vacuum at the following pressure. 3. A method for measuring the surface potential of a substrate placed in a vacuum.
Surface potential measuring device that can be deformed or displaced
In this state, a conductor is placed facing the substrate with a predetermined gap.
The Coulomb force acting between the body plate and the substrate and conductor plate
Detection of the magnitude of deformation or displacement of the conductor plate caused by
Output means and the surface voltage of the substrate based on the detection result of the detection means.
Calculating means for calculating the position, wherein the pressure in the gap between the substrate and the conductor plate is distributed by the substrate.
Vacuum pressure of the space in which the
A container surrounding the space opposite to the side where the substrate is placed
Provided, the pressure in the container is a vacuum, the substrate is placed
Is characterized by being the same as the vacuum pressure of
Characteristic surface potential measuring device. 4. The surface potential measuring device according to claim 3 , wherein the container is provided with an opening communicating with a space in which the substrate is arranged. 5. The one of claims 1 to 4, characterized in that the distance between the substrate and the conductor plate is variable
Surface treatment apparatus of the crab according. 6. The detecting means comprises: an electrode plate provided on the opposite side of the conductor plate to the substrate and facing the conductor plate; and a conductor plate and an electrode formed by deformation or displacement of the conductor plate. claims 1 to 5 Izu, characterized in that is made of a capacitance meter for detecting a change in capacitance between the plate
A surface potential measuring device according to any one of the preceding claims. 7. The detection means, wherein a long magnet provided on the conductor plate so as to extend on a side opposite to the side of the conductor plate facing the substrate, and lines of magnetic force of the long magnet interlink. a coil disposed so as to, one of claims 1 to 5, characterized in that the deformation or displacement of the conductor plate is made of a current meter for detecting an induced current generated in the coil by displacement elongated magnet surface treatment apparatus of the crab according. 8. by placing a substrate in a vacuum chamber equipped with an exhaust system and a substrate processing apparatus for performing predetermined processing, claim 1
A substrate processing apparatus comprising the surface potential measuring device according to any one of claims 1 to 7 . 9. A substrate processing apparatus for performing a predetermined process by arranging a substrate in a vacuum vessel provided with an exhaust system.
A substrate processing apparatus comprising: the surface potential measuring device according to claim 1; and wherein the exhaust system is capable of evacuating the inside of the vacuum vessel to a high vacuum having a pressure of 10 ⁻³ Pa or less. 10. The surface potential of a substrate placed in a vacuum
A method for measuring surface potential, which can be deformed or displaced
The conductor plate facing the board with a predetermined gap
And the Coulomb force acting between the substrate and the conductor plate.
The magnitude of the deformation or displacement of the conductor plate caused by the
The surface voltage of the substrate based on the detection result of the detection means.
A method of calculating the position by a calculating means, The pressure in the gap between the substrate and the conductor plate is controlled by the substrate.
Vacuum pressure of the space in which the
The pressure in the space opposite to the side where the substrate is
It is the same as the vacuum pressure of the space where the plate is placed
Surface potential measurement method.