State detection method and circuit applied to electrostatic chuck and storage medium

Abstract

The invention relates to the technical field of semiconductor processing, in particular to a state detection method and circuit applied to an electrostatic chuck and a storage medium, and the method comprises the following steps: superposing a high-voltage direct-current voltage with a low-voltage alternating-current voltage to form an alternating-current and direct-current fusion signal; inputting the AC-DC fusion signal to two ends of an electrostatic chuck; detecting an alternating current and direct current fusion signal flowing through the electrostatic chuck, and separating an alternating current signal from the alternating current and direct current fusion signal; calculating the capacitive reactance and capacitance value of the electrostatic chuck according to the alternating current signal; according to the capacitance value and the capacitance threshold value, the state between the electrostatic chuck and the wafer is judged, wherein the state between the electrostatic chuck and the wafer comprises the states that no wafer exists on the electrostatic chuck, no wafer exists on the chuck but no electrostatic adsorption force exists on the chuck, and no wafer exists on the chuck and the electrostatic adsorption force exists on the chuck. According to the invention, the adsorption state of the wafer and the electrostatic chuck is detected in the whole process, the stable adsorption of the wafer in the process flow is ensured, the condition of wafer etching errors is reduced, and the good rate of finished products is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor processing, and in particular to a state detection method, circuit and storage medium applied to an electrostatic chuck. Background Art

[0002] In the early days, mechanical clamping was used. This traditional fixing method may not only scratch the wafer, but also cause the wafer to break if strong force is applied to a specific part, and there will be warping areas where the wafer is subjected to uneven force. If vacuum adsorption is used, it is impossible to use a decompression adsorption method like a suction cup. The advantages and disadvantages of various adsorption methods are compared as follows:

[0003]

[0004] In semiconductor processing, the fixation of wafers is very important. If the position of the silicon wafer cannot be fixed, the uniformity of the processing will not be ensured during the processing of the wafer, and the processing accuracy will be greatly affected. The use of electrostatic chucks to fix the wafer has a more uniform adsorption force and can fix the wafer in a non-contact manner, with more stable performance and better consistency.

[0005] In the existing related technologies, such as the patent application with publication number CN117855069A, a method, circuit, equipment, and medium for detecting the state of a chip on an electrostatic chuck are disclosed. An alternating power supply module is used to provide an alternating power supply to the positive electrode and the negative electrode of the electrostatic chuck so that the electrostatic chuck is in a detected state, and then the state of the chip on the electrostatic chuck is determined according to the measured load capacitance value at the positive electrode and the load capacitance at the positive electrode and the negative electrode. This patent can judge the state of the chip according to the load capacitance values ​​at the positive electrode and the negative electrode. On the premise of understanding the state of the chip, it will help to improve the safety of the chip transmission process and avoid chip collision; and the state of the chip can be obtained without manual cavity opening, which reduces manpower expenditure, avoids long-term process production interruption caused by cavity opening, and improves work efficiency.

[0006] However, the existing related technologies are only applicable to detection before the process starts and at the end of the process, and cannot achieve real-time detection throughout the entire process. Therefore, in order to further improve the accuracy of wafer detection, a state detection method, circuit and storage medium for an electrostatic chuck are provided. Summary of the invention

[0007] Taking into account the problem that it is impossible to accurately judge whether the wafer and the chuck are well adsorbed, the present invention proposes a state detection method, circuit and storage medium for an electrostatic chuck, which detects the size of the capacitance between the wafer and the electrostatic chuck, and then judges the current adsorption status of the wafer and the chuck in a high-precision manner.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A state detection method for an electrostatic chuck comprises the following steps:

[0010] A high-voltage DC voltage is superimposed on a low-voltage AC voltage to form an AC / DC fusion signal, wherein the high-voltage DC voltage is used to provide an adsorption force to the electrostatic chuck;

[0011] Among them, when used for a bipolar electrostatic chuck, two AC / DC fusion signals are required, and there is a phase difference between the AC signals in the two AC / DC fusion signals, which act on the positive and negative polarity chucks respectively;

[0012] When used for a unipolar chuck, only one AC / DC fusion signal is needed to act on the unipolar chuck;

[0013] Inputting the AC / DC fusion signal to both ends of the electrostatic chuck; detecting the AC / DC fusion signal flowing through the electrostatic chuck, and separating the AC signal therein;

[0014] The capacitive reactance of the electrostatic chuck is calculated according to the AC signal, and the capacitance value is converted according to the capacitive reactance;

[0015] The state between the electrostatic chuck and the wafer is determined based on the capacitance value and the capacitance threshold, wherein the state between the electrostatic chuck and the wafer includes no wafer on the electrostatic chuck, a wafer on the chuck but no electrostatic adsorption force, and a wafer on the chuck and an electrostatic adsorption force.

[0016] As a preferred solution, when used in a bipolar electrostatic chuck, the phases of the two AC signals are complementary.

[0017] As a preferred solution, the electrostatic chuck is equivalent to a capacitor and a resistor connected in parallel.

[0018] As a preferred solution, when the equivalent resistance value of the electrostatic chuck is much larger than the capacitive reactance value of the electrostatic chuck, the capacitance value is calculated by the voltage value, current value and phase. When the fRC≥1 criterion is met, the electrostatic chuck is equivalent to a capacitor. f is the frequency of the low-voltage AC voltage signal, U is the effective value of the low-voltage AC voltage, and I is the effective value of the low-voltage AC current; among them, U and f are emitted by the AC and DC output units, and their values ​​are known and do not need to be tested, so only the only variable needs to be tested: I.

[0019] As a preferred solution, a capacitance threshold is set according to the relationship between the wafer and the electrostatic chuck, including a threshold C1 when there is no wafer on the electrostatic chuck, in which case C≤C1; a threshold C2 when there is a wafer on the electrostatic chuck, when C1<C<C2, the electrostatic chuck does not adsorb the wafer; when C2≤C, the electrostatic chuck adsorbs the wafer, and C is the capacitance value converted based on the capacitive reactance.

[0020] As a preferred solution, when used for a bipolar chuck, judging the state between the electrostatic chuck and the wafer by the capacitance threshold includes two situations, which are as follows:

[0021] The capacitance value of the positive and negative polarity detection is integrated. C o1 is the positive polarity capacitance value, C o2 is the negative polarity capacitance value, and the state between the electrostatic chuck and the wafer is determined by comparing it with the threshold value;

[0022] The detected positive and negative polarity capacitance values ​​are compared with the threshold values ​​respectively, and the states between the positive and negative polarity chucks and the wafer are determined respectively.

[0023] A state detection circuit applied to an electrostatic chuck, comprising an AC / DC output unit, a detection unit and an electrostatic chuck;

[0024] The AC / DC output unit outputs an AC / DC fusion signal to both ends of the electrostatic chuck; the AC / DC fusion signal is formed by superimposing a high-voltage DC voltage on a low-voltage AC voltage, and the high-voltage DC voltage is used to provide an adsorption force to the electrostatic chuck;

[0025] The detection unit is used to detect the AC / DC fusion signal flowing through the electrostatic chuck, separate the AC signal therein, calculate the capacitive reactance of the electrostatic chuck according to the AC signal, and convert the capacitance value according to the capacitive reactance;

[0026] The state between the electrostatic chuck and the wafer is determined based on the capacitance value and the capacitance threshold, wherein the state between the electrostatic chuck and the wafer includes no wafer on the electrostatic chuck, a wafer on the chuck but no electrostatic adsorption force, and a wafer on the chuck and an electrostatic adsorption force.

[0027] As a preferred solution, the electrostatic chuck is equivalent to a capacitor and a resistor connected in parallel, and the connection relationship between the electrostatic chuck and the wafer is determined based on the capacitance value and the capacitance threshold.

[0028] Based on the same concept, a storage medium is also proposed, on which instructions executable by a processor are stored. When the instructions are executed by the processor, the processor executes any of the above-mentioned state detection methods for an electrostatic chuck.

[0029] In summary, due to the adoption of the above technical scheme, the beneficial effects of the present invention are: the method and circuit of the present invention detect the capacitive reactance at both ends of the electrostatic chuck by superimposing a low-voltage AC voltage under the condition of high-voltage DC power supply, and then analyze the connection relationship between the electrostatic chuck and the wafer. In the application scenario of high-voltage DC circuit, the detection method can perform real-time detection in the entire process, and the wafer status detection accuracy is higher, thereby reducing the probability of wafer damage, and has the advantages of low power consumption, safety and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is the equivalent circuit of the monopolar electrostatic chuck in Example 1;

[0031] Figure 2 This is a schematic diagram of a monopolar electrostatic chuck in Example 1;

[0032] Figure 3 Schematic diagram of a bipolar electrostatic chuck in Example 1;

[0033] Figure 4 is an equivalent circuit diagram of the bipolar electrostatic chuck in Example 1;

[0034] Figure 5 This is a flow chart of a state detection method applied to an electrostatic chuck in Example 1;

[0035] Figure 6 The voltage / current waveforms collected at both ends of the unipolar electrostatic chuck in Example 1;

[0036] Figure 7 is an equivalent circuit diagram of the electrostatic chuck in Example 1;

[0037] Figure 8 Schematic diagram of the phase difference between the effective value of the AC current and the load AC voltage and current in Example 2;

[0038] Fig. 9 This is the waveform diagram of the AC / DC fusion signal required to be injected into the bipolar electrostatic chuck. DETAILED DESCRIPTION

[0039] The present invention is described in detail below in conjunction with the accompanying drawings. In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] Example 1

[0041] When a DC power supply applies voltage to the electrodes of the suction cup, an electric field is formed between the electrodes. This electric field propagates between the insulating layer and the ceramic adsorption surface and extends to the back of the wafer. The electric field causes the charge on the surface of the wafer to be redistributed or polarized, and finally, under the action of electrostatic force, the wafer is firmly adsorbed on the suction cup. The magnitude of the electrostatic adsorption force can be approximately calculated by Coulomb's law and the electric field strength. Assuming that the electric field of the wafer and the suction cup is uniform, the electrostatic force F can be expressed as:

[0042]

[0043] Among them, ε0 is the vacuum permittivity (8.85×10-12F / m), ε r is the dielectric constant which depends on the insulating layer material, E is the electric field strength which is equal to the applied voltage V divided by the insulating layer thickness d, A is the effective area of ​​the electrode.

[0044] In addition, the capacitance between the wafer and the electrostatic chuck is

[0045] Then, the electrostatic force between the wafer and the chuck is

[0046] During the electrostatic adsorption process, the silicon wafer essentially acts as the upper plate of the capacitor, thus forming a circuit. Therefore, for the electrostatic chuck and wafer, the equivalent capacitance method can be used. The system between the electrostatic chuck and the wafer is equivalent to a capacitor system composed of electrodes, dielectric layers, gaps, and wafers. The capacitance value can be calculated based on the structure of the electrostatic chuck and the wafer, and then the electrostatic force between them can be solved to determine the adsorption effect between the wafer and the chuck. There is a capacitor and resistor between the electrode and the inside of the wafer, which is composed of the wafer oxide layer, gap layer, and dielectric layer in series. Its equivalent circuit is as follows: Figure 1 As shown, Figure 1 This is the equivalent circuit of a monopolar electrostatic chuck.

[0047] According to the number of electrodes, the actual application of electrostatic chuck can be divided into two types: monopolar type and bipolar type. Figure 2 As shown. Figure 2 It can be seen that the monopolar electrostatic chuck has only one electrode. In order to generate electrostatic adsorption force, voltage needs to be applied to the silicon wafer, that is, electrostatic attraction can only be generated when plasma is working.

[0048] Schematic diagram of bipolar electrostatic chuck Figure 3 As shown: The bipolar electrostatic chuck has two electrodes, and its equivalent circuit is as follows: Figure 4 As shown, the working principle is similar to that of a unipolar chuck.

[0049] When used for a bipolar electrostatic chuck, two AC / DC fusion signals are required, and there is a phase difference between the AC signals in the two AC / DC fusion signals, which act on the positive and negative polarity chucks respectively; the most preferred two AC signals are complementary in phase, which has higher signal detection accuracy and less impact on the adsorption effect of the bipolar suction cup.

[0050] During the processing, if the wafer is not completely adsorbed, it may cause it to shift, thus affecting the etching accuracy. Therefore, the quality of the finished wafer is closely related to whether it is completely adsorbed. Figure 2 , Figure 4 Analysis can be done by calculating the interaction force between the capacitor plates and analyzing the adsorption force of the electrostatic chuck to obtain the wafer status. However, the force cannot be directly measured in a simple way.

[0051] The equivalent capacitance of the actual electrostatic chuck during the process of adsorbing the wafer is related to its state: the capacitance is smallest when there is no wafer on the electrostatic chuck; the capacitance increases when there is a wafer on the electrostatic chuck but it is not adsorbed; the capacitance is largest when the electrostatic chuck adsorbs the wafer well. Therefore, the actual capacitance between the electrostatic chuck and the wafer can be calculated to determine the presence status of the wafer.

[0052] A state detection method for an electrostatic chuck, the flow chart is as follows Figure 5 As shown, the following steps are included:

[0053] A high-voltage DC voltage is superimposed on a low-voltage AC voltage to form an AC-DC fusion signal, wherein the high-voltage DC voltage is used to provide an adsorption force to the electrostatic chuck, wherein the high-voltage DC voltage can be any value or any DC waveform;

[0054] Inputting the AC / DC fusion signal to both ends of the electrostatic chuck; detecting the AC / DC fusion signal flowing through the electrostatic chuck, and separating the AC signal therein;

[0055] The capacitive reactance of the electrostatic chuck is calculated according to the AC signal, and the capacitance value is converted according to the capacitive reactance;

[0056] The state between the electrostatic chuck and the wafer is determined based on the capacitance value and the capacitance threshold, wherein the state between the electrostatic chuck and the wafer includes no wafer on the electrostatic chuck, a wafer on the chuck but no electrostatic adsorption force, and a wafer on the chuck and an electrostatic adsorption force.

[0057] After the method is applied to the wafer and electrostatic chuck status detection scenario, the method detects the status of the wafer and the electrostatic chuck by detecting the capacitance value between the capacitor plates in the high-voltage circuit, ensuring the stable adsorption of the wafer in the process flow, reducing the abnormalities of the wafer processing process, and improving the yield rate.

[0058] Taking the scenario of semiconductor electrostatic chuck and wafer connection as an example, further explanation is as follows:

[0059] like Figure 6 As shown, Figure 6 The figure below shows the voltage / current waveform collected at both ends of the electrostatic chuck. The peak-to-peak value of the voltage is △U, the peak-to-peak value of the current is △I, the effective value of the voltage is U, the effective value of the current is I, the voltage and current have the same frequency f, and the current leads the voltage by a phase angle of φ.

[0060] like Fig. 9 As shown, Fig. 9 The bipolar electrostatic chuck requires the AC and DC output units to send out AC and DC fusion signals respectively. Its principle is similar to that of the unipolar electrostatic chuck. The signal required for detecting the capacitance is determined by the joint action of the two AC and DC output units.

[0061] like Figure 7 As shown, Figure 7 This is the equivalent circuit diagram of the electrostatic chuck. The input is a unit that can output AC and DC. The AC and DC signals are injected into the equivalent model of the electrostatic chuck. Among them, the DC component is mainly used to generate the adsorption force between the electrostatic chuck and the wafer. The AC component is a small AC sinusoidal signal superimposed on the high-voltage DC signal, which is mainly used to detect the capacitance value of the load end shown. The detection unit is mainly used to collect the AC component.

[0062] The relationship between voltage and current is expressed by the following equation:

[0063]

[0064] ω=2πf;

[0065] set up

[0066] but

[0067]

[0068] Among them, U is the effective value of AC voltage, I is the effective value of AC current, and f is the frequency value of AC sinusoidal small signal. The above three parameters can be obtained by testing instruments. R is the load impedance value, C is the load capacitance value, It is the angle between the load capacitance and impedance, that is, the phase difference between the output AC voltage and current.

[0069] By combining equation ① and equation ②, we can calculate the capacitance value of the output load.

[0070]

[0071] Therefore, in order to find the capacitance value of the output load end, it is necessary to find the effective value of the AC voltage, the effective value of the AC current, and the phase difference of the load AC voltage and current. The schematic diagram is as follows: Figure 8 shown.

[0072] This scheme is actually applied to the capacitance detection of the electrostatic chuck, and three states of the wafer are set: non-existent (no wafer on the chuck), present but not adsorbed (there is a wafer on the chuck, but there is no electrostatic adsorption force between the two or the electrostatic adsorption force cannot guarantee the fixation of the wafer in the process flow), and good adsorption (the electrostatic adsorption force can guarantee the fixation of the wafer in the process flow).

[0073] And the capacitance range is defined as follows:

[0074] 1. In practical applications, two capacitance thresholds, threshold C1 and threshold C2, can be set. Reasonable thresholds can be set according to the relationship between the wafer and the chuck in the current process. The current capacitance value read by this method is compared with the threshold to judge the current process effect.

[0075] 2. The relationship between the current wafer state and the capacitance threshold is: when C≤C1, the wafer does not exist; when C1<C<C2, the wafer exists but is not adsorbed; when C2≤C, the wafer is well adsorbed.

[0076] When used for a bipolar chuck, there are two situations in which the state between the electrostatic chuck and the wafer is judged by the capacitance threshold, as follows:

[0077] The capacitance value of the positive and negative polarity detection is integrated. C o1 is the positive polarity capacitance value, C o2 is the negative polarity capacitance value, and the state between the electrostatic chuck and the wafer is determined by comparing it with the threshold value;

[0078] The detected positive and negative polarity capacitance values ​​are compared with the threshold values ​​respectively, and the states between the positive and negative polarity chucks and the wafer are determined respectively.

[0079] Example 2

[0080] Based on the above analysis, further, in actual implementation, given that the purpose of capacitance detection is to determine the current adsorption status of the wafer and the chuck, the measurement can be weakened without excessively losing accuracy, taking into account the actual detection cost, difficulty of the means, etc.

[0081] Since the equivalent resistance between the electrostatic chuck and the wafer is very high, generally several hundred KΩ, and the equivalent capacitance is generally less than 100nF, when the appropriate value is taken, the phase angle between the AC voltage and current is generally large, close to 0°.

[0082] In the actual detection process, it is not convenient to obtain the phase difference between voltage and current in real time. The following simplified method can be used.

[0083]

[0084] Among them, U is the effective value of AC voltage, I is the effective value of AC current, |Z| is the modulus of load impedance, Xc is the load capacitive reactance, and f is the frequency of AC signal.

[0085] From the formula, we can see that when fRC≥1, |Z|≈X c , at this time, the calculation is performed in the form of pure capacitance.

[0086] Theoretical error:

[0087]

[0088] At this time there is Right now Only the effective values ​​of the AC voltage and AC current are needed to calculate the actual capacitance of the electrostatic chuck, and the theoretical error is much less than 1.24%.

[0089] The AC voltage value is set by the user according to the actual process, so the AC voltage value and frequency value are known. It is possible to detect only one variable: the effective value of the AC current, and then obtain the capacitance value, and further deduce the adsorption force.

[0090] This scheme is actually applied to the capacitance detection of the electrostatic chuck, and three states of the wafer are set: non-existent (no wafer on the chuck), present but not adsorbed (there is a wafer on the chuck, but there is no electrostatic adsorption force between the two or the electrostatic adsorption force cannot guarantee the fixation of the wafer in the process flow), and good adsorption (the electrostatic adsorption force can guarantee the fixation of the wafer in the process flow).

[0091] And the capacitance range is defined as follows:

[0092] 1. In practical applications, two capacitance thresholds, threshold C1 and threshold C2, can be set. Reasonable thresholds can be set according to the relationship between the wafer and the chuck in the current process. The current capacitance value read by this method is compared with the threshold to judge the current process effect.

[0093] 2. The relationship between the current wafer state and the capacitance threshold is: when C≤C1, the wafer does not exist; when C1<C<C2, the wafer exists but is not adsorbed; when C2≤C, the wafer is well adsorbed.

[0094] 3. When fRC is much larger than 1, a simple method can be used to more accurately detect the capacitance value. Therefore, it is necessary to match a more reasonable f (frequency) value according to different wafers and different chuck types.

[0095] It should be noted that the equivalent circuit between the electrostatic chuck and the wafer is exemplified in the form of RC parallel equivalent circuit. When other components are included or optimization changes are made to the equivalent circuit, the above detection method is still applicable.

[0096] This embodiment provides an effective solution to detect the wafer status during the entire process, ensure the stable adsorption of the wafer during the process, reduce the wafer etching errors, and improve the good rate of the finished product. It provides a feasible idea for other situations where the capacitance value needs to be detected in high-voltage circuits.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A state detection method for an electrostatic chuck, characterized in that: The following steps are involved: A high-voltage DC voltage is superimposed on a low-voltage AC voltage to form an AC / DC fusion signal, wherein the high-voltage DC voltage is used to provide an adsorption force to the electrostatic chuck; Among them, when used for a bipolar electrostatic chuck, two AC / DC fusion signals are required, and there is a phase difference between the AC signals in the two AC / DC fusion signals, which act on the positive and negative polarity chucks respectively; When used for a unipolar chuck, only one AC / DC fusion signal is needed to act on the unipolar chuck; Inputting the AC / DC fusion signal to both ends of the electrostatic chuck; detecting the AC / DC fusion signal flowing through the electrostatic chuck, and separating the AC signal therein; The capacitive reactance of the electrostatic chuck is calculated according to the AC signal, and the capacitance value is converted according to the capacitive reactance; The state between the electrostatic chuck and the wafer is determined based on the capacitance value and the capacitance threshold, wherein the state between the electrostatic chuck and the wafer includes no wafer on the electrostatic chuck, a wafer on the chuck but no electrostatic adsorption force, and a wafer on the chuck and an electrostatic adsorption force.

2. A state detection method for an electrostatic chuck according to claim 1, characterized in that: When used in a bipolar electrostatic chuck, the two AC signals are complementary in phase.

3. A state detection method for an electrostatic chuck according to claim 1, characterized in that: The electrostatic chuck is equivalent to a capacitor and a resistor connected in parallel.

4. A state detection method for an electrostatic chuck as claimed in claim 3, characterized in that: The capacitance is calculated by voltage, current and phase. When the fRC≥1 criterion is met, the electrostatic chuck is equivalent to a capacitor, and the capacitance value is , f is the frequency of the low-voltage AC voltage signal, U is the effective value of the low-voltage AC voltage, and I is the effective value of the low-voltage AC current.

5. A state detection method for an electrostatic chuck according to claim 1, characterized in that: The capacitance threshold is set according to the relationship between the wafer and the electrostatic chuck, including the threshold C1 when there is no wafer on the electrostatic chuck, in which case C≤C1; the threshold C2 when there is a wafer on the electrostatic chuck, when C1<C<C2, the electrostatic chuck does not adsorb the wafer; when C2≤C, the electrostatic chuck adsorbs the wafer, and C is the capacitance value converted based on the capacitive reactance.

6. A state detection method for an electrostatic chuck as claimed in claim 5, characterized in that: When used for a bipolar chuck, there are two situations in which the state between the electrostatic chuck and the wafer is judged by the capacitance threshold, as follows: The capacitance value of the positive and negative polarity detection is integrated. , is the positive polarity capacitance value, is the negative polarity capacitance value, and the state between the electrostatic chuck and the wafer is determined by comparing it with the threshold value; The detected positive and negative polarity capacitance values ​​are compared with the threshold values ​​respectively, and the states between the positive and negative polarity chucks and the wafer are determined respectively.

7. A state detection circuit for an electrostatic chuck, characterized in that: It includes an AC / DC output unit, a detection unit and an electrostatic chuck; The AC / DC output unit outputs an AC / DC fusion signal to both ends of the electrostatic chuck; the AC / DC fusion signal is formed by superimposing a high-voltage DC voltage on a low-voltage AC voltage, and the high-voltage DC voltage is used to provide an adsorption force to the electrostatic chuck; The detection unit is used to detect the AC / DC fusion signal flowing through the electrostatic chuck, separate the AC signal therein, calculate the capacitive reactance of the electrostatic chuck according to the AC signal, and convert the capacitance value according to the capacitive reactance; The state between the electrostatic chuck and the wafer is determined based on the capacitance value and the capacitance threshold, wherein the state between the electrostatic chuck and the wafer includes no wafer on the electrostatic chuck, a wafer on the chuck but no electrostatic adsorption force, and a wafer on the chuck and an electrostatic adsorption force.

8. A state detection circuit for an electrostatic chuck as claimed in claim 7, characterized in that: The electrostatic chuck is equivalent to a capacitor and a resistor in parallel, and the connection relationship between the electrostatic chuck and the wafer is determined based on the capacitance value and the capacitance threshold.

9. A storage medium, characterized in that: Instructions executable by a processor are stored thereon, and when the instructions are executed by the processor, the processor executes a state detection method applied to an electrostatic chuck as claimed in any one of claims 1 to 6.

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