Apparatus and method for inspecting an electrostatic chuck for substrate processing

Abstract

An apparatus for inspecting an electrostatic chuck for substrate processing, the apparatus including: an electrostatic chuck including a ceramic layer and an electrode layer coupled to an inner portion of the ceramic layer; an ultrasonic sensor unit disposed on the electrostatic chuck to allow ultrasonic waves to be incident into the electrostatic chuck and to convert a reflected signal reflected through the electrostatic chuck into an ultrasonic voltage signal; and an ultrasonic inspection unit to divide the ceramic layer and the electrode layer based on a magnitude value of the ultrasonic voltage signal.

Description

Technical Field

[0001] The embodiments of this disclosure described herein relate to apparatus and methods for inspecting electrostatic chucks used in substrate processing, and more specifically, to apparatus and methods for inspecting electrostatic chucks capable of using ultrasonic waves. Background Technology

[0002] Typically, electrostatic chucks (ESCs) use electrostatic forces to attract objects such as substrates. The total electrostatic force (F) of an electrostatic chuck is... 总 ) by F 库仑 The sum of F and Johnson-Labeckheem (FJ-R) is used to represent the sum, where F 库仑 It is expressed as α*0.5*ε1*ε2*A1*(V1 / D1)2 (α = constant, ε1 = vacuum dielectric constant, ε2 = specific dielectric constant, A1 = area of ​​non-contact region, V1 = applied voltage, and D1 = thickness of dielectric material), and the Johnson-Rabeel force is expressed as β*0.5*ε2*A2*(V2 / D2)2 (β = constant, ε2 = vacuum dielectric constant, A2 = area of ​​contact region, V2 = applied voltage, and D2 = roughness of ceramic surface).

[0003] In this case, when the resistance of the ceramic constituting the electrostatic chuck is 1E16 or higher, the Coulomb force is significantly greater than the Johnson-Rabe force. Therefore, the area (A2) of the contact region where the substrate overlaps with the electrode does not have a significant impact. Consequently, when the electrode voltage is turned off, the substrate easily separates from the electrostatic chuck.

[0004] However, when the resistance of the ceramic constituting the electrostatic chuck is in the range of 1E9 to 1E13, the Johnson-Rabe force increases significantly. Therefore, the area (A2) of the contact region where the substrate overlaps with the electrode has a significant impact. Consequently, when the electrode voltage is turned off, the substrate is less likely to separate from the electrostatic chuck. In this case, when the electrode diameter increases by 1 mm, the area (A2) of the contact region where the substrate overlaps with the electrode increases by 10% or more. Therefore, when the electrode voltage is turned off, the substrate will not separate from the electrostatic chuck.

[0005] Therefore, when inspecting an electrostatic chuck, the area of ​​the electrodes should be checked. However, according to traditional methods for inspecting electrostatic chucks, no technical solution has yet been proposed for checking the electrode area.

[0006] Meanwhile, in nondestructive testing, there is an ultrasonic testing method, which is only used to probe the interior of an object to check for cracks or pores inside. When using ultrasonic testing to calculate the offset of an electrostatic chuck relative to the electrode, the area of ​​the electrode, or the thickness of the electrode, additional technical solutions are necessary for the calculation. Summary of the Invention

[0007] Embodiments of this disclosure provide apparatus and methods for inspecting electrostatic chucks used in substrate processing, which can measure the offset of the electrostatic chuck relative to electrodes by using ultrasonic waves during the inspection of the electrostatic chuck.

[0008] Embodiments of the present invention provide an apparatus and method for inspecting an electrostatic chuck used for substrate processing, which enables the measurement of the electrode area of ​​the electrostatic chuck by using ultrasonic waves during inspection.

[0009] Furthermore, embodiments of the present invention provide an apparatus and method for inspecting an electrostatic chuck used for substrate processing, which enables the thickness of the electrostatic chuck to be measured by using ultrasonic waves during inspection.

[0010] According to an embodiment, an apparatus for inspecting an electrostatic chuck used for substrate processing includes: an electrostatic chuck comprising a ceramic layer and an electrode layer, the electrode layer being coupled to the interior of the ceramic layer; an ultrasonic sensor unit disposed on the electrostatic chuck to allow ultrasonic waves to be incident into the electrostatic chuck and to convert reflected signals reflected through the electrostatic chuck into ultrasonic voltage signals; and an ultrasonic inspection unit configured to distinguish the ceramic layer and the electrode layer based on the magnitude of the ultrasonic voltage signals.

[0011] According to an embodiment, the ultrasonic inspection unit includes an image conversion unit electrically connected to the ultrasonic sensor unit to receive ultrasonic voltage signals from the ultrasonic sensor unit for the entire area to be inspected by the electrostatic chuck, and to convert the ultrasonic voltage signals into ultrasonic image information.

[0012] According to embodiments of this disclosure, the pixel values ​​constituting ultrasonic image information are set to have different brightness levels for different levels of the voltage amplitude of the ultrasonic voltage signal.

[0013] According to an embodiment, the ultrasonic inspection unit further includes a scaling conversion unit, which receives ultrasonic image information of the electrostatic chuck by interacting with the image transformation unit, so as to adjust the scale of the received ultrasonic image information of the electrostatic chuck so that the scale of the ultrasonic image information of the electrostatic chuck matches the actual size of the electrostatic chuck.

[0014] According to an embodiment, the ultrasonic inspection unit further includes a non-overlapping region extraction unit, which is used to receive ultrasonic image information of the electrostatic chuck having an actual ratio that is adjusted by interaction with the scaling unit, and to extract non-overlapping regions in which the ceramic layer and the electrode layer do not overlap based on the received ultrasonic image information of the electrostatic chuck.

[0015] According to an embodiment, the ultrasonic inspection unit further includes an electrode spacing calculation unit, which receives the pixel coordinate values ​​of the inner and outer boundary lines of the non-overlapping region by interacting with the non-overlapping region extraction unit, calculates the width between the inner and outer boundary lines, and calculates the spacing between the ceramic layer and the electrode layer.

[0016] According to an embodiment, the ultrasonic inspection unit further includes an electrode area calculation unit, which receives the spacing by interacting with the electrode spacing calculation unit, and subtracts the spacing from the previously measured diameter value of the ceramic layer while storing the diameter value therein, and calculates the area of ​​the electrode layer using the circular area formula (radius * circumference).

[0017] According to an embodiment, the ultrasonic inspection unit includes an electrode thickness calculation unit, which calculates the thickness of the electrode layer using the following Equation 1.

[0018] Equation 1

[0019] S0 = 0.5 * V1(t1 - t0)

[0020] (S0 = thickness of the electrode layer, V1 = speed of sound when the ultrasonic wave passes through the electrode layer, t1 = time taken for the ultrasonic wave output from the ultrasonic sensor unit to be reflected through the electrode layer, and t0 = measurement delay time from the ultrasonic generator until the ultrasonic voltage signal is generated).

[0021] According to an embodiment, when performing a detection operation, the ultrasonic sensor unit performs the detection operation by allowing the focus of the ultrasonic wave to exist on the surface of the ceramic layer.

[0022] According to an embodiment, the device may further include an inspection tank unit for containing a liquid medium, such that the electrostatic chuck is immersed in the liquid medium.

[0023] According to an embodiment, the ultrasonic sensor unit is immersed in a liquid medium and is configured to be separated from the electrostatic chuck.

[0024] According to an embodiment, a method for inspecting an electrostatic chuck used for substrate processing includes: when an ultrasonic sensor unit generates ultrasonic waves, operating the ultrasonic sensor unit to output a reflected wave in the form of a voltage waveform, the reflected wave returning after the ultrasonic waves pass through the electrostatic chuck; and generating an ultrasonic image by analyzing the magnitude value of the voltage waveform of the reflected signal detected by the ultrasonic sensor unit through an image transformation unit, thereby generating ultrasonic image information of the electrostatic chuck, the ultrasonic image information having different brightness for each level of the magnitude value of the voltage waveform.

[0025] According to an embodiment, the method for inspecting an electrostatic chuck used for substrate processing further includes: adjusting the scale of an ultrasonic image via a scaling unit to receive ultrasonic image information of the electrostatic chuck by interacting with an image transformation unit, thereby adjusting the scale of the ultrasonic image information of the electrostatic chuck so that the scale of the ultrasonic image information of the electrostatic chuck matches the actual size of the electrostatic chuck.

[0026] According to an embodiment, the method for inspecting an electrostatic chuck used for substrate processing further includes: extracting non-overlapping regions by a non-overlapping region extraction unit by receiving ultrasonic image information of an electrostatic chuck whose actual size is adjusted in interaction with a scaling unit, and performing a division operation such that regions with mutually different information in pixel brightness are divided into regions with ultrasonic image information of the electrostatic chuck with adjusted scaling, calculating the spacing between the non-overlapping regions divided in the non-overlapping region extraction unit by an electrode spacing calculation unit, and subtracting the spacing from the previously measured diameter value of the ceramic layer while storing the diameter value therein, so as to calculate the area of ​​the electrode layer by using a circular area formula.

[0027] According to an embodiment, the method for inspecting an electrostatic chuck used for substrate processing further includes: measuring the electrode layer from an ultrasonic sensor unit using an electrode thickness calculation unit to measure the time (t1) until the ultrasonic wave is reflected through the electrode layer, and calculating the thickness of the electrode layer using Equation 1 below, which includes previously stored constant values.

[0028] Equation 1

[0029] S0 = 0.5 * V1(t1 - t0)

[0030] (S0 = thickness of the electrode layer, V1 = speed of sound when the ultrasonic wave passes through the electrode layer, t1 = time taken for the ultrasonic wave output from the ultrasonic sensor unit to be reflected through the electrode layer, and t0 = measurement delay time from the ultrasonic generator until the ultrasonic voltage signal is generated).

[0031] According to an embodiment, the method for inspecting an electrostatic chuck used for substrate processing further includes: setting the substrate by placing the electrostatic chuck in an inspection tank unit filled with a liquid medium before driving the ultrasonic sensor unit.

[0032] According to an embodiment, in a method for inspecting an electrostatic chuck used for substrate processing, when setting the substrate, an ultrasonic sensor unit is immersed in a liquid medium and is positioned separately from the electrostatic chuck.

[0033] According to an embodiment, the method for inspecting an electrostatic chuck used for substrate processing further includes setting the ultrasonic sensor unit by moving it to a check point on a preset drive command by a scanning drive unit before driving the ultrasonic sensor unit.

[0034] According to an embodiment, in a method for inspecting an electrostatic chuck used for substrate processing, the pixel values ​​constituting ultrasonic image information are set to have different brightness levels depending on the magnitude of the ultrasonic voltage signal.

[0035] According to an embodiment, an apparatus for inspecting an electrostatic chuck used for substrate processing includes: an electrostatic chuck comprising a ceramic layer and an electrode layer, the electrode layer being coupled to the interior of the ceramic layer; an ultrasonic sensor unit disposed on the electrostatic chuck to allow ultrasonic waves to be incident into the electrostatic chuck and to convert reflected signals reflected through the electrostatic chuck into ultrasonic voltage signals; and an ultrasonic inspection unit configured to distinguish the ceramic layer and the electrode layer based on the magnitude of the ultrasonic voltage signals.

[0036] The ultrasonic inspection unit includes an image conversion unit electrically connected to the ultrasonic sensor unit to receive ultrasonic voltage signals from the entire area to be inspected of the electrostatic chuck from the ultrasonic sensor unit and convert the ultrasonic voltage signals into ultrasonic image information.

[0037] The pixel values ​​that constitute the ultrasonic image information are set to have different brightness levels for different levels of the ultrasonic voltage signal amplitude.

[0038] The ultrasonic inspection unit also includes a scaling unit, which receives ultrasonic image information from the electrostatic chuck by interacting with the image transformation unit, so as to adjust the scale of the received ultrasonic image information of the electrostatic chuck to match the actual size of the electrostatic chuck.

[0039] The ultrasonic inspection unit also includes a non-overlapping region extraction unit, which receives ultrasonic image information from the electrostatic chuck with an actual scale adjusted by interaction with the scaling unit, and extracts non-overlapping regions where the ceramic layer and electrode layer do not overlap based on the received ultrasonic image information from the electrostatic chuck.

[0040] The ultrasonic inspection unit also includes an electrode spacing calculation unit, which receives the pixel coordinate values ​​of the inner and outer boundary lines of the non-overlapping region by interacting with the non-overlapping region extraction unit, calculates the width between the inner and outer boundary lines, and calculates the spacing between the ceramic layer and the electrode layer.

[0041] The ultrasonic inspection unit also includes an electrode area calculation unit, which receives the spacing by interacting with the electrode spacing calculation unit, subtracts the spacing from the previously measured diameter value of the ceramic layer while storing the diameter value therein, and calculates the area of ​​the electrode layer using the circular area formula (radius * circumference).

[0042] The ultrasonic inspection unit also includes an electrode thickness calculation unit, which calculates the thickness of the electrode layer using Equation 1 below.

[0043] Equation 1

[0044] S0 = 0.5 * V1(t1 - t0)

[0045] (S0 = thickness of the electrode layer, V1 = speed of sound when the ultrasonic wave passes through the electrode layer, t1 = time taken for the ultrasonic wave output from the ultrasonic sensor unit to be reflected through the electrode layer, and t0 = measurement delay time from the ultrasonic generator until the ultrasonic voltage signal is generated).

[0046] When performing a detection operation, the ultrasonic sensor unit performs the detection operation by allowing the focus of the ultrasonic wave to exist on the surface of the ceramic layer.

[0047] The device also includes an inspection tank unit for containing a liquid medium, which allows the electrostatic chuck to be immersed in the liquid medium.

[0048] The ultrasonic sensor unit is immersed in a liquid medium and is configured to be isolated from the electrostatic chuck. Attached Figure Description

[0049] The above and other objectives and features of this disclosure will become apparent from the detailed description of embodiments thereof with reference to the accompanying drawings.

[0050] Figure 1 This is a block diagram illustrating an apparatus for inspecting an electrostatic chuck used for substrate processing according to an embodiment of the present disclosure.

[0051] Figure 2 yes Figure 1 A partial cross-sectional view of the enlarged area to be inspected on the electrostatic chuck shown.

[0052] Figure 3 It shows the use Figure 1 The image shown is a photograph of the electrostatic chuck taken by the ultrasonic image processing unit.

[0053] Figure 4 It is the voltage waveform of the reflected wave measured by the ultrasonic sensor unit when using ultrasonic waves to inspect the electrode layer of an electrostatic chuck.

[0054] Figure 5This is a flowchart of a method for inspecting an electrostatic chuck used for substrate processing, according to an embodiment of the present disclosure. Detailed Implementation

[0055] In the following description, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the description below, when a part "includes" a component, that part does not exclude other components, but other components may also be included if specifically described otherwise. Furthermore, terms such as "unit" refer to a unit that performs at least one function or operation, and are considered in the description of machine devices as a part, function, purpose, point, or driving component. Additionally, in the following description, the same or similar components will be given the same reference numerals, and repeated descriptions of the same reference numerals will be omitted to avoid redundancy.

[0056] Figure 1 This is a block diagram illustrating an apparatus for inspecting an electrostatic chuck according to an embodiment of the present disclosure. Figure 2 yes Figure 1 A partial cross-sectional view of the enlarged area to be inspected on the electrostatic chuck shown. Figure 3 It shows the use Figure 1 The image shown is a photograph of the electrostatic chuck taken by the ultrasonic image processing unit. Figure 4 It is the voltage waveform of the reflected wave measured by the ultrasonic sensor unit when using ultrasonic waves to inspect the electrode layer of an electrostatic chuck.

[0057] like Figure 1 As shown, the apparatus for inspecting an electrostatic chuck used for substrate processing according to an embodiment of the present disclosure includes an inspection water tank unit 10, an ultrasonic sensor unit 20, a scanning drive unit 30, and an ultrasonic inspection unit 40.

[0058] The inspection tank unit 10 is formed in the form of a tank with an open upper portion, and an electrostatic chuck 1 is disposed on the inner bottom surface of the inspection tank unit 10. In this case, a liquid medium is contained in the inspection tank unit 10. In this case, the liquid medium may include water, and other liquid media may be included if necessary. As described above, the inspection tank unit 10 is configured such that when the electrostatic chuck 1 is immersed in the liquid medium, the probe of the ultrasonic sensor unit 20 is immersed in the liquid medium, but direct contact between the electrostatic chuck 1 and the ultrasonic sensor unit 20 is prevented. Therefore, when the electrostatic chuck 1 is inspected using ultrasound, the ultrasonic sensor unit 20 can easily transmit ultrasonic waves to the electrostatic chuck 1 through the liquid medium. Furthermore, since direct contact between the ultrasonic sensor unit 20 and the electrostatic chuck 1 is prevented, scratches to the electrostatic chuck 1 due to direct contact between the ultrasonic sensor unit 20 and the electrostatic chuck 1 are prevented. In this case, the electrostatic chuck 1 disposed inside the inspection tank unit 10 is an electrostatic chuck 1 that attracts substrates such as wafers by electrostatic force. According to this embodiment, the electrostatic chuck 1 includes: a ceramic layer 1a formed of ceramic; an electrode layer 1b inserted into the ceramic layer 1a; and an adhesive layer formed below the electrode layer 1b and bonded to an alumina layer (not shown). In this case, the ceramic layer 1a has an embossed portion 1c formed on its top surface, an outer dam region 1d formed on the outer side of the outermost portion of the embossed portion 1c, and an inner dam region 1e formed on the inner side of the outermost embossed portion 1c.

[0059] An ultrasonic sensor unit 20 is disposed in the upper part of the inspection tank unit 10, and its lower end is inserted into the liquid medium. In this configuration, the ultrasonic sensor unit 20 includes: an ultrasonic pulse generator (not shown) that generates ultrasonic waves; and an ultrasonic receiver (not shown) that receives the reflected waves when the ultrasonic waves generated by the ultrasonic pulse generator pass through the electrostatic chuck 1 and are reflected. Furthermore, the ultrasonic sensor unit 20 is mounted with a scanning drive unit 30 and moves according to a preset drive command from the scanning drive unit 30, while simultaneously allowing ultrasonic waves to be incident on the electrostatic chuck 1 and receiving the reflected waves, converting the reflected signals into ultrasonic voltage signals. In this configuration, the ultrasonic sensor unit 20 performs an ultrasonic scanning operation to obtain ultrasonic voltage signals for the entire area to be inspected on the electrostatic chuck 1, thereby ensuring ultrasonic voltage signals for every micro-region of the entire plane of the area to be inspected. As described above, when the density of the ceramic differs from the density of the electrode, the ultrasonic sensor unit 20 detects the ceramic layer 1a and electrode layer 1b of the electrostatic chuck by changing the output voltage therein. In this case, the ultrasonic sensor unit 20 has an ultrasonic frequency in the range of 50MHz to 100MHz, and performs a detection operation by allowing the focus of the ultrasonic wave to exist on the surface of the ceramic layer 1a, so that when the detection operation is performed, the ceramic layer 1a can be distinguished from the electrode 1b with a higher probability.

[0060] The scanning drive unit 30 is configured as a multi-degree-of-freedom transmission device, and is configured to have an ultrasonic sensor unit 20 at one end. In this case, the scanning drive unit 30 moves the ultrasonic sensor unit 20 while moving according to a preset drive command. The scanning drive unit 30 fixes the ultrasonic sensor unit 20 to prevent it from hitting the electrostatic chuck 1 and scratching it, and moves the ultrasonic sensor unit 20 to its current position to ensure accurate ultrasonic images during ultrasonic inspection.

[0061] The ultrasonic inspection unit 40 includes an image transformation unit 41, a scaling conversion unit 42, a non-overlapping region extraction unit 43, an electrode spacing calculation unit 44, an electrode area calculation unit 45, and an electrode thickness calculation unit 46.

[0062] The image conversion unit 41 is electrically connected to the ultrasonic sensor unit 20 and receives ultrasonic voltage signals from the ultrasonic sensor unit 20 for the entire area to be inspected from the electrostatic chuck 1, converting the ultrasonic voltage signals into ultrasonic image information. In this case, the ultrasonic image information includes, for example... Figure 3The image shows the ultrasonic image information of the electrostatic chuck 1. In this case, when converting the ultrasonic signal into ultrasonic image information, the image conversion unit 41 is configured such that the pixel values ​​constituting the ultrasonic image information have different brightness level information according to the voltage amplitude of the ultrasonic voltage signal. Therefore, the image conversion unit 41 pre-stores a brightness information table containing information about 256 brightness levels divided according to voltage amplitude, determines the brightness level information matching the magnitude of the ultrasonic voltage signal's voltage amplitude in the brightness information table, and outputs the brightness level information corresponding to the magnitude of the voltage amplitude as pixel information. In this case, the brightness level information can output pixel information where the brightness increases with the increase of the level. However, according to this disclosure, the brightness information is not limited to the above 256 levels. For example, the brightness level can be adjusted if needed.

[0063] The scaling unit 42 receives the ultrasonic image information of the electrostatic chuck 1 by interacting with the image transformation unit 41, and adjusts the scaling of the ultrasonic image information of the electrostatic chuck 1 so that the ultrasonic image information of the electrostatic chuck 1 matches the actual size of the electrostatic chuck 1. In this case, the scaling unit 42 can adjust the grid coordinate value of each pixel of the ultrasonic image information of the electrostatic chuck 1 to match the actual size of the electrostatic chuck 1.

[0064] The non-overlapping region extraction unit 43 receives ultrasonic image information from the electrostatic chuck 1, which has an actual scale adjusted by interaction with the scaling unit 42, and extracts a non-overlapping region 1f in which the ceramic layer 1a and the electrode layer 1b do not overlap based on the received ultrasonic image information from the electrostatic chuck 1. More specifically, the non-overlapping region extraction unit 43 receives the ultrasonic image information of the electrostatic chuck 1 adjusted to the actual scale by interaction with the scaling unit 42, and performs a segmentation operation such that regions with mutually different information in pixel brightness are segmented into regions with the ultrasonic image information of the electrostatic chuck 1 at the adjusted scale. In this case, regarding regions with mutually different information in pixel brightness information, in the ultrasonic image information with the scale adjusted by the scaling unit 42, the overlapping region between the ceramic layer 1a and the electrode layer 1b is formed to have a specific brightness or higher. In this case, the non-overlapping region in which the ceramic layer 1a does not overlap with the electrode layer 1b is formed to have information about lower brightness, but the information about brightness is higher than the information about black. Furthermore, the medium region that only has the medium and does not have the ceramic layer 1a and the electrode layer 1b is formed to be black.

[0065] The electrode spacing calculation unit 44 receives the pixel coordinate values ​​of the inner boundary line 2b and outer boundary line 2c of the non-overlapping region 1f through the interactive non-overlapping region extraction unit 43, calculates the width between the inner boundary line 2b and the outer boundary line 2c, and calculates the spacing 2a between the ceramic layer 1a and the electrode layer 1b. According to this embodiment, as shown in the attached figures, the spacing 2a of the non-overlapping region 1f is formed to be 1.15 micrometers. As described above, for example, assuming a virtual line extends from the center point of the electrostatic chuck 1 to the outer periphery of the electrostatic chuck 1, the electrode spacing calculation unit 44 can receive the pixel coordinate values ​​of the inner boundary line 2b and outer boundary line 2c of the non-overlapping region 1f through interaction with the non-overlapping region extraction unit 43, and can calculate the distance between the inner interconnection point between the virtual line and the inner boundary line 2b and the outer interconnection point between the virtual line and the outer boundary line 2c. Since the virtual line is generated for each angle in this manner, the entire spacing 2a between the outer boundary line 2c and the inner boundary line 2b of the electrode layer 1b can be calculated. In this configuration, the electrostatic chuck tester can identify the degree of separation between the electrode layer 1b and the ceramic layer 1a based on the spacing 2a. Therefore, it can be determined whether the spacing between the electrode layer 1b and the ceramic layer 1a exceeds a specific deviation, thereby determining whether the electrode layer 1b is offset.

[0066] The electrode area calculation unit 45 receives the spacing 2a through interaction with the electrode spacing calculation unit 44. With the measured diameter value stored therein, it subtracts the spacing 2a from the diameter value of the ceramic layer 1a and calculates the area of ​​the electrode layer 1b using the circular area formula (radius * circumference). In this case, when the calculated area of ​​the electrode layer 1b exceeds a preset reference area value, the electrode area calculation unit 45 determines that the electrostatic chuck 1 is defective and outputs a defect alarm during inspection of the electrostatic chuck 1 to more effectively inspect it.

[0067] The electrode thickness calculation unit 46 is a component for calculating the thickness of the electrode layer 1b, which can calculate the thickness of the electrode layer 1b using the following equation 1.

[0068] Equation 1

[0069] S0 = 0.5 * V1(t1 - t0)

[0070] (S0 = thickness of electrode layer 1b, V1 = speed of sound when the ultrasonic wave passes through electrode layer 1b, t1 = time taken for the ultrasonic wave output from ultrasonic sensor unit 20 to be reflected through electrode layer 1b, and t0 = measurement delay time until the ultrasonic generator generates an ultrasonic voltage signal).

[0071] In this case, V1, t1, and t0 are values ​​measured experimentally and stored in the electrode thickness calculation unit 46.

[0072] like Figure 4 As shown, the electrode layer 1b is measured by the ultrasonic sensor unit 20, and the electrode thickness calculation unit 46 receives the time t1 taken for the ultrasonic wave to be reflected through the electrode layer 1b, so that the area of ​​the electrode layer 1b can be calculated using Equation 1. In this case, the ultrasonic sensor unit 20 is configured to focus on the top surface of the electrode layer 1b to measure the thickness of the electrode layer 1b. Next, the electrode thickness calculation unit 46 calculates the thickness S0 of the electrode layer 1b by substituting the sound velocity V1 of the ultrasonic wave passing through the electrode layer 1b and the measurement delay time t0 of the ultrasonic sensor unit, where the sound velocity is a value pre-stored experimentally.

[0073] In the following, a method for inspecting an electrostatic chuck for substrate processing will be described using an apparatus for inspecting an electrostatic chuck for substrate processing, according to embodiments of the present disclosure.

[0074] Figure 5 This is a flowchart of a method for inspecting an electrostatic chuck used for substrate processing, according to an embodiment of the present disclosure.

[0075] like Figure 5 As shown, an apparatus for inspecting an electrostatic chuck for substrate processing according to an embodiment of the present disclosure includes the following steps: setting a substrate (S10), setting an ultrasonic sensor unit (S20), operating the ultrasonic sensor unit (S30), generating an ultrasonic image (S40), adjusting the scale of the ultrasonic image (S50), extracting non-overlapping regions (S60), calculating the electrode spacing (S70), calculating the electrode area (S80), and calculating the electrode thickness (S90).

[0076] First, in the step of setting the substrate (S10), the ceramic layer 1a of the electrostatic chuck 1, in which the electrode layer 1b is provided, is placed in the inspection water tank unit 10 filled with liquid medium.

[0077] Next, in the step of setting up the ultrasonic sensor unit (S20), the scanning drive unit 30 moves the ultrasonic sensor unit 20 to the inspection point according to the preset drive command.

[0078] Next, in the step (S30) of operating the ultrasonic sensor unit, when the ultrasonic sensor unit generates ultrasonic waves, it outputs the reflected wave that returns after passing through the electrostatic chuck in the form of a voltage waveform.

[0079] Next, in the step of generating an ultrasonic image (S40), the image transformation unit 41 analyzes the magnitude of the voltage waveform of the reflected signal detected by the ultrasonic sensor unit 20 to generate ultrasonic image information of the electrostatic chuck 1. For each level of the magnitude of the voltage waveform, the ultrasonic image information is formed with different brightness.

[0080] Then, in the step of adjusting the scale of the ultrasonic image (S50), the scale conversion unit 42 receives the ultrasonic image information of the electrostatic chuck 1 by interacting with the image conversion unit 41, and adjusts the scale of the ultrasonic image information of the electrostatic chuck 1 to match the actual size of the electrostatic chuck 1.

[0081] Subsequently, in the step of extracting non-overlapping regions (S60), the non-overlapping region extraction unit 43 receives the ultrasonic image information of the electrostatic chuck 1 with adjusted actual size by interacting with the scaling conversion unit 42, and performs a division operation so that regions with different information in pixel brightness are divided into regions with ultrasonic image information of the electrostatic chuck 1 with adjusted scale.

[0082] Then, in the step of calculating the electrode spacing (S70), the electrode spacing calculation unit 44 calculates the spacing 2a between the non-overlapping regions 1f divided in the non-overlapping region extraction unit 43. In this case, in the step of calculating the electrode spacing (S70), the electrode spacing calculation unit 44 can calculate the spacing 2a of the electrode layers by performing numerical interpolation on the boundary lines between the non-overlapping regions 1f as described above.

[0083] Subsequently, in the step of calculating the electrode area (S80), with the previously measured diameter value of the ceramic layer 1a stored therein, the area of ​​the electrode layer 1b is calculated by subtracting the spacing 2a from the diameter value of the ceramic layer 1a using the circular area formula (radius * circumference). In this case, in the step of calculating the electrode area (S80), when the calculated area of ​​the electrode layer 1b exceeds a preset reference area value, the electrode area calculation unit 45 determines that the electrostatic chuck 1 is defective and outputs a defect alarm when inspecting the electrostatic chuck 1 to more effectively inspect the electrostatic chuck 1.

[0084] Next, in the step of calculating the electrode thickness (S90), the electrode thickness calculation unit 46 measures the electrode layer 1b from the ultrasonic sensor unit 20, measures the time t1 until the ultrasonic wave is reflected through the electrode layer 1b, and calculates the thickness S0 of the electrode layer 1b using Equation 1, which includes previously stored constant values.

[0085] As described above, in the apparatus and method for inspecting an electrostatic chuck according to embodiments of the present disclosure, since the spacing 2a of the electrode layer 1b is calculated, the offset phenomenon of the electrostatic chuck 1 can be measured.

[0086] As described above, in the apparatus and method for inspecting an electrostatic chuck according to embodiments of the present disclosure, the area of ​​the electrostatic chuck 1 can be measured by the spacing 2a of the front layers.

[0087] Furthermore, according to embodiments of this disclosure, in the apparatus and method for inspecting an electrostatic chuck used for substrate processing, the thickness of the electrostatic chuck 1 can be measured by using ultrasonic waves.

[0088] According to this disclosure, since the spacing between the electrode layers is calculated, the offset phenomenon of the electrodes of the electrostatic chuck can be measured.

[0089] Furthermore, according to this disclosure, the area of ​​an electrostatic chuck can be measured based on the spacing between the electrode layers.

[0090] Furthermore, according to this disclosure, when inspecting an electrostatic chuck, the thickness of the electrostatic chuck can be measured using ultrasound.

[0091] In the foregoing, although the present disclosure has been described with reference to embodiments and accompanying drawings, the present disclosure is not limited thereto, but can be modified and altered by those skilled in the art without departing from the spirit and scope of the present disclosure as claimed in the appended claims.

[0092] Although the spirit of this disclosure has been described with reference to embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications may be made thereto without departing from the spirit and scope of this disclosure as set forth in the appended claims.

Claims

1. An apparatus for inspecting an electrostatic chuck used for substrate processing, the apparatus comprising: An electrostatic chuck, the electrostatic chuck comprising a ceramic layer and an electrode layer, the electrode layer being connected to the interior of the ceramic layer; An ultrasonic sensor unit, disposed on the electrostatic chuck, configured to allow ultrasonic waves to be incident into the electrostatic chuck, and configured to convert reflected signals passing through the electrostatic chuck into ultrasonic voltage signals; and An ultrasonic inspection unit is configured to divide the ceramic layer and the electrode layer based on the frequency value of the ultrasonic voltage signal.

2. The apparatus according to claim 1, wherein the ultrasonic inspection unit comprises: An image conversion unit is electrically connected to the ultrasonic sensor unit to receive ultrasonic voltage signals from the ultrasonic sensor unit for the entire area to be inspected by the electrostatic chuck, and to convert the ultrasonic voltage signals into ultrasonic image information.

3. The apparatus of claim 2, wherein the pixel values ​​constituting the ultrasonic image information are set to have different brightness levels for different voltage amplitude levels of the ultrasonic voltage signal.

4. The apparatus according to claim 2, wherein the ultrasonic inspection unit further comprises: A scaling conversion unit receives the ultrasonic image information of the electrostatic chuck by interacting with the image transformation unit, so as to adjust the scale of the received ultrasonic image information of the electrostatic chuck so that the scale of the ultrasonic image information of the electrostatic chuck matches the actual size of the electrostatic chuck.

5. The apparatus according to claim 4, wherein the ultrasonic inspection unit further comprises: A non-overlapping region extraction unit is used to receive ultrasonic image information of the electrostatic chuck, which has an actual ratio adjusted by interaction with the scaling unit, and to extract non-overlapping regions where the ceramic layer and the electrode layer do not overlap based on the received ultrasonic image information of the electrostatic chuck.

6. The apparatus according to claim 5, wherein the ultrasonic inspection unit further comprises: An electrode spacing calculation unit receives the pixel coordinate values ​​of the inner and outer boundary lines of the non-overlapping region by interacting with the non-overlapping region extraction unit, calculates the width between the inner and outer boundary lines, and calculates the spacing between the ceramic layer and the electrode layer.

7. The apparatus according to claim 6, wherein the ultrasonic inspection unit further comprises: An electrode area calculation unit receives the spacing by interacting with the electrode spacing calculation unit, and with the diameter value stored therein, subtracts the spacing from the previously measured diameter value of the ceramic layer, and calculates the area of ​​the electrode layer using the circular area formula (radius * circumference).

8. The apparatus according to claim 1, wherein the ultrasonic inspection unit comprises: The electrode thickness calculation unit calculates the thickness of the electrode layer using the following equation 1. Equation 1 S0 = 0.5 * V1(t1 - t0) S0 = thickness of the electrode layer, V1 = speed of sound when the ultrasonic wave passes through the electrode layer, t1 = time taken for the ultrasonic wave output from the ultrasonic sensor unit to be reflected by the electrode layer, and t0 = measurement delay time until the ultrasonic generator generates an ultrasonic voltage signal.

9. The apparatus of claim 1, wherein when performing a detection operation, the ultrasonic sensor unit performs the detection operation by allowing the focus of the ultrasonic wave to exist on the surface of the ceramic layer.

10. The apparatus according to claim 1, further comprising: Inspect the water tank unit, which is used to contain the liquid medium, so that the electrostatic chuck is immersed in the liquid medium.

11. The apparatus of claim 10, wherein the ultrasonic sensor unit is immersed in the liquid medium and is configured to be spaced apart from the electrostatic chuck.

12. A method for inspecting an electrostatic chuck used for substrate processing, the method comprising: When the ultrasonic sensor unit generates ultrasonic waves, the ultrasonic sensor unit is operated to output the reflected wave of the ultrasonic waves after passing through the electrostatic chuck in the form of a voltage waveform. The electrostatic chuck includes a ceramic layer and an electrode layer, and the electrode layer is connected to the interior of the ceramic layer. as well as An ultrasonic image is generated by analyzing the magnitude of the voltage waveform of the reflected signal detected by the ultrasonic sensor unit using an image transformation unit, thereby generating ultrasonic image information of the electrostatic chuck with different brightness for each level of the magnitude of the voltage waveform, wherein the reflected signal is in the form of an ultrasonic voltage signal.

13. The method of claim 12, further comprising: The scale of the ultrasonic image is adjusted by a scaling conversion unit to receive the ultrasonic image information of the electrostatic chuck by interacting with the image transformation unit, thereby adjusting the scale of the ultrasonic image information of the electrostatic chuck so that the scale of the ultrasonic image information of the electrostatic chuck matches the actual size of the electrostatic chuck.

14. The method of claim 13, further comprising: The non-overlapping region extraction unit extracts non-overlapping regions by receiving the ultrasonic image information of the electrostatic chuck having the actual size adjusted through interaction with the scaling unit, and performs a segmentation operation such that regions with mutually different information in pixel brightness are segmented into regions having the ultrasonic image information of the electrostatic chuck with the adjusted scale. The spacing between the non-overlapping regions divided in the non-overlapping region extraction unit is calculated by the electrode spacing calculation unit; as well as With the diameter value stored therein, the spacing is subtracted from the previously measured diameter value of the ceramic layer to calculate the area of ​​the electrode layer using the circular area formula.

15. The method of claim 12, further comprising: The electrode thickness is measured by an electrode thickness calculation unit to measure the time (t1) until the ultrasonic wave generated by the ultrasonic sensor unit is reflected through the electrode layer, and the thickness of the electrode layer is calculated using Equation 1, which includes previously stored constant values. Equation 1 S0 = 0.5 * V1(t1 - t0) S0 = thickness of the electrode layer, V1 = speed of sound when the ultrasonic wave passes through the electrode layer, t1 = time taken for the ultrasonic wave output from the ultrasonic sensor unit to be reflected by the electrode layer, and t0 = measurement delay time until the ultrasonic generator generates an ultrasonic voltage signal.

16. The method of claim 12, further comprising: Before driving the ultrasonic sensor unit The substrate is set by placing the electrostatic chuck in an inspection tank unit filled with a liquid medium.

17. The method of claim 16, wherein in the arrangement of the substrate, the ultrasonic sensor unit is immersed in the liquid medium and is configured to be spaced apart from the electrostatic chuck.

18. The method of claim 12, further comprising: Before driving the ultrasonic sensor unit The ultrasonic sensor unit is set by moving it to the check point according to a preset drive command by the scanning drive unit.

19. The method of claim 12, wherein the pixel values ​​constituting the ultrasonic image information are set to have different brightness levels corresponding to the voltage amplitude of the ultrasonic voltage signal.

20. An apparatus for inspecting an electrostatic chuck used for substrate processing, the apparatus comprising: An electrostatic chuck, the electrostatic chuck comprising a ceramic layer and an electrode layer, the electrode layer being connected to the interior of the ceramic layer; An ultrasonic sensor unit, disposed on the electrostatic chuck and configured to allow ultrasonic waves to be incident on the electrostatic chuck, and to convert reflected signals passing through the electrostatic chuck into ultrasonic voltage signals; and An ultrasonic inspection unit is configured to distinguish the ceramic layer and the electrode layer based on the frequency of the ultrasonic voltage signal. The ultrasonic inspection unit includes: An image conversion unit, electrically connected to the ultrasonic sensor unit, receives ultrasonic voltage signals from the ultrasonic sensor unit for the entire area to be inspected by the electrostatic chuck, and converts the ultrasonic voltage signals into ultrasonic image information. The pixel values ​​constituting the ultrasonic image information are set to have different brightness levels for different voltage amplitude levels of the ultrasonic voltage signal. The ultrasonic inspection unit further includes: A scaling unit receives the ultrasonic image information of the electrostatic chuck by interacting with the image transformation unit, and adjusts the scale of the received ultrasonic image information of the electrostatic chuck so that the scale of the ultrasonic image information of the electrostatic chuck matches the actual size of the electrostatic chuck. The ultrasonic inspection unit further includes: A non-overlapping region extraction unit is configured to receive ultrasonic image information of the electrostatic chuck, having an actual scale adjusted through interaction with the scaling unit, and extract non-overlapping regions between the ceramic layer and the electrode layer based on the received ultrasonic image information of the electrostatic chuck. The ultrasonic inspection unit further includes: An electrode spacing calculation unit receives the pixel coordinate values ​​of the inner and outer boundary lines of the non-overlapping region by interacting with the non-overlapping region extraction unit, calculates the width between the inner and outer boundary lines, and calculates the spacing between the ceramic layer and the electrode layer. The ultrasonic inspection unit further includes: An electrode area calculation unit receives the spacing by interacting with the electrode spacing calculation unit. With the diameter value stored therein, the unit subtracts the spacing from the previously measured diameter value of the ceramic layer and calculates the area of ​​the electrode layer using the circular area formula (radius * circumference). The ultrasonic inspection unit further includes: The electrode thickness calculation unit calculates the thickness of the electrode layer using the following equation 1. Equation 1 S0 = 0.5 * V1(t1 - t0) S0 = thickness of the electrode layer, V1 = speed of sound when the ultrasonic wave passes through the electrode layer, t1 = time taken for the ultrasonic wave output from the ultrasonic sensor unit to be reflected by the electrode layer, and t0 = measurement delay time from when the ultrasonic generator produces an ultrasonic voltage signal. When performing a detection operation, the ultrasonic sensor unit performs the detection operation by allowing the focus of the ultrasonic wave to be located on the surface of the ceramic layer. The device further includes: Inspect the water tank unit, which is used to contain the liquid medium, such that the electrostatic chuck is immersed in the liquid medium, and The ultrasonic sensor unit is immersed in the liquid medium and is configured to be separated from the electrostatic chuck.

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