JP7052584B2 - Plasma processing equipment and plasma processing method - Google Patents

Description

The present disclosure relates to a plasma processing apparatus and a plasma processing method.

In the manufacturing process of a flat panel display (FPD), there is a process of performing an etching process or a film forming process on a substrate by using plasma. This process involves placing the substrate on a mounting table in a vacuum vessel and applying high frequency energy to the processing gas supplied to the space above the mounting table to generate, for example, capacitively coupled plasma or inductively coupled plasma. Will be done. The mounting table used in such a plasma processing apparatus may be provided with a substrate fixing mechanism called, for example, an electrostatic chuck. The electrostatic chuck has a configuration in which an electrostatic adsorption electrode is arranged in a dielectric layer, and by applying a DC voltage to the electrostatic adsorption electrode, electrostatic adsorption is performed between the electrostatic adsorption electrode and the substrate. Force works to hold the substrate on the table.

Patent Document 1 describes a technique for detecting peeling of a substrate from the mounting table by monitoring the DC voltage supplied to the electrostatic adsorption electrode when the substrate is electrostatically adsorbed on the mounting table. In this technology, when the monitored DC voltage exceeds a preset threshold value, it is determined that the substrate has peeled off from the mounting table, and the high-frequency power to the high-frequency power supply for plasma generation is stopped.

Japanese Unexamined Patent Publication No. 2016-174081

The present disclosure has been made under such circumstances, and an object of the present invention is to provide a technique for accurately detecting partial peeling of a large substrate from a mounting table when plasma treatment is performed.

The plasma processing apparatus of the present disclosure is provided in a vacuum container for performing plasma processing on a substrate, and has a mounting table on which the substrate to be processed is placed.
An electrostatic adsorption electrode that is placed in the dielectric layer provided on the above-mentioned pedestal and electrostatically adsorbs the substrate placed on the above-mentioned pedestal,
A DC power supply that applies a DC voltage corresponding to a preset voltage set value to the electrostatic adsorption electrode, and
A high-frequency power supply unit that generates high-frequency power for generating plasma of processing gas in the vacuum vessel and supplying it to the substrate, and a high-frequency power supply unit.
A voltage measuring unit that measures the DC voltage applied to the electrostatic adsorption electrode, and
A difference value acquisition unit that acquires a difference value corresponding to the difference between the measured value of the DC voltage measured by the voltage measurement unit and the voltage set value, and the difference value acquisition unit.
An amplification unit that amplifies the difference value acquired by the difference value acquisition unit and acquires the amplification value,
The amplification value is compared with a threshold value preset for the amplification value, and when the amplification value exceeds the threshold value, high-frequency power is supplied from the high-frequency power supply unit. It is equipped with a control unit that outputs a control signal for stopping.
The DC power supply, the voltage measuring unit, the difference value acquisition unit, and the amplification unit are provided in a common power supply unit.
The amplification value is output from the power supply unit to the control unit, and
The power supply unit is characterized in that, in addition to the amplified value, a DC voltage measured by the voltage measuring unit is output to the control unit .
Alternatively, the plasma processing apparatus of the present disclosure is provided in a vacuum container for performing plasma processing on a substrate, and has a mounting table on which the substrate to be processed is placed.
An electrostatic adsorption electrode that is placed in the dielectric layer provided on the above-mentioned pedestal and electrostatically adsorbs the substrate placed on the above-mentioned pedestal,
A DC power supply that applies a DC voltage corresponding to a preset voltage set value to the electrostatic adsorption electrode, and
A high-frequency power supply unit that generates high-frequency power for generating plasma of processing gas in the vacuum vessel and supplying it to the substrate, and a high-frequency power supply unit.
A voltage measuring unit that measures the DC voltage applied to the electrostatic adsorption electrode, and
A difference value acquisition unit that acquires a difference value corresponding to the difference between the measured value of the DC voltage measured by the voltage measurement unit and the voltage set value, and the difference value acquisition unit.
An amplification unit that amplifies the difference value acquired by the difference value acquisition unit and acquires the amplification value,
The amplification value is compared with a threshold value preset for the amplification value, and when the amplification value exceeds the threshold value, high-frequency power is supplied from the high-frequency power supply unit. It is equipped with a control unit that outputs a control signal for stopping.
The amplification unit obtains the amplification value by multiplying the difference value by a preset amplification factor.
The amplification factor is the area ratio (area ratio =) of the area S (m ² ) of the substrate on which the plasma treatment is performed to the area of the reference size substrate when the substrate having an area of 2.78 m ² is used as the reference size substrate. It is characterized in that it is set to a value obtained by multiplying S / 2.78) by 1 to 10.

According to the present disclosure, it is possible to accurately detect partial peeling of a large substrate from a mounting table when performing plasma treatment.

It is a vertical sectional side view of the plasma processing apparatus which concerns on one Embodiment. It is explanatory drawing explaining the partial peeling from the pedestal of a glass substrate. It is explanatory drawing which shows the principle that the change of DC voltage occurs when the partial peeling of a glass substrate occurs. It is a block diagram which shows the voltage monitor part provided in the said plasma processing apparatus. It is a graph which shows the time-dependent change of a voltage and a differential amplification value when peeling of a glass substrate does not occur. It is a graph which shows the time-dependent change of a voltage and a differential amplification value when peeling of a glass substrate occurs. It is a flowchart which shows the operation of the plasma processing apparatus of this disclosure. It is explanatory drawing which shows the relationship between the voltage measured value and the differential amplification value.

The plasma processing apparatus according to one embodiment will be described. As shown in FIG. 1, the plasma processing apparatus includes a processing container (vacuum container) 10 made of, for example, aluminum or stainless steel, which is connected to a ground potential. A carry-in outlet 11 for delivering, for example, a rectangular glass substrate G, which is a substrate to be plasma-treated, is provided on the side surface of the processing container 10, and a gate valve 12 for opening and closing the carry-in outlet is provided at the carry-in outlet 11. It is provided. Further, an exhaust port 13 is opened on the lower side surface of the processing container 10, and each exhaust port 13 is provided with a vacuum exhaust portion 15 via an exhaust pipe 14.

Inside the processing container 10, a prismatic mounting table 3 having a rectangular planar shape is provided on which the glass substrate G is placed. The detailed configuration of the mounting table 3 will be described later.
Further, above the processing container 10, a spiral inductively coupled antenna 70, which is a plasma forming portion, is provided via a window member (not shown) made of a dielectric or a metal so as to face the mounting table 3. .. A source power source (source power supply unit) 72 for plasma generation is connected to the inductively coupled antenna 70 via a matching unit 71. Then, by supplying source power (high frequency power for generating plasma) from the source power source 72 to the inductively coupled antenna 70, an electric field for plasma generation can be generated in the processing container 10.

Further, below the inductively coupled antenna 70 and the window member (not shown), a shower head 2 for supplying the processing gas into the processing container 10 is provided. The shower head 2 is fixed to the top plate portion of the processing container 10 via the insulating portion 16, and a large number of gas supply holes 21 are formed on the lower surface of the shower head 2 so as to face the mounting surface of the mounting table 3. Has been done. The shower head 2 includes a gas dispersion chamber 20 to which a gas supply hole 21 is connected to the inside, and a processing gas supply pipe 22 for supplying the processing gas toward the gas dispersion chamber 20 is provided on the upper surface of the shower head 2. It is connected. The processing gas supply pipe 22 is provided with a processing gas supply source 23 for supplying a processing gas containing an etching gas such as CF ₄ or Cl ₂ , a flow rate adjusting unit M22, and a valve V22 in this order from the upstream side. Has been done.

Next, the mounting table 3 will be described. The mounting table 3 has a structure in which the spacer 35 and the susceptor 33 are laminated in this order from the lower layer side, and the side surfaces of these members 35 and 33 are covered with, for example, a ceramic cover 38. The mounting table 3 is installed at the center of the bottom surface of the processing container 10 via the insulating layer 39. A bias power supply (bias power supply unit) 75 is connected to the susceptor 33 via the wiring 73. Reference numeral 74 in FIG. 1 is a matching device for matching the bias power. When a bias power, which is a high frequency power, is applied to the susceptor 33 by the bias power source 75, the active species of the processing gas generated in the processing container 10 by plasma can be drawn into the glass substrate G placed on the mounting table 3. In this example, the source power supply 72 and the bias power supply 75 correspond to the high frequency power supply unit.

A heat transfer gas supply path 34 is provided inside the mounting table 3, and the end portion on the downstream side thereof is branched into a plurality of parts and dispersed and opened on the upper surface of the mounting table 3, whereby a plurality of heat transfer paths are transferred. It constitutes a gas supply port 34a. The upstream side of the heat transfer gas supply path 34 is connected to the heat transfer gas supply pipe 62 provided outside the processing container 10, and the upstream side of the heat transfer gas supply pipe 62 is transferred via the flow rate adjusting unit 63. It is connected to the heat gas supply source 64.

Inside the spacer 35, for example, an annular refrigerant flow path 36 extending in the circumferential direction is provided. A heat conduction medium adjusted to a predetermined temperature is circulated and supplied to the refrigerant flow path 36 by a chiller unit (not shown), and the processing temperature of the glass substrate G can be controlled by the temperature of the heat conduction medium. There is.

Further, on the mounting table 3, an elevating pin (not shown) for transferring the glass substrate G to and from the external transport arm vertically penetrates the bottom plate portion of the mounting table 3 and the processing container 10, and the mounting table 3 is used. It is provided so as to sink from the surface of the glass.
As shown in FIG. 1, a dielectric layer 31 is provided on the upper surface of the susceptor 33, and an electrostatic adsorption electrode 32 made of a metal that spreads in the horizontal direction is embedded in the dielectric layer 31. The electrostatic adsorption electrode 32 is connected to the power supply unit 400 via a wiring 41 provided with a voltage adjusting resistor 42. The power supply unit 400 includes a DC power supply 40 and a voltage monitoring unit 5 for monitoring the DC voltage applied to the electrostatic adsorption electrode 32. The DC power supply 40 is connected to the wiring 41 via a voltage adjusting resistor 40a. The DC power supply 40 is configured so that, for example, a preset DC voltage in the range of 0 to 6000 V can be applied to the electrostatic adsorption electrode 32 based on a voltage set value input from a control unit 9 described later, for example. There is.

In the above-mentioned plasma processing apparatus, when a DC voltage is applied to the electrostatic adsorption electrode 32, an electrostatic attractive force is generated between the electrostatic adsorption electrode 32 and the glass substrate G via the dielectric layer 31 to generate glass. The substrate G can be sucked and held. However, if the glass substrate G is peeled off from the surface of the mounting table 3, plasma enters between the glass substrate G and the mounting table 3, causing an abnormal discharge or damaging the surface of the mounting table 3. May affect.

Therefore, in the plasma processing apparatus of this example, the voltage monitor unit 5 described above is used to detect the peeling of the glass substrate G from the mounting table 3. On the other hand, the boards processed during the manufacture of FPDs are becoming larger and larger, and some of them have a side of about 3 meters. The inventors have found that as the size of the glass substrate G increases, it becomes difficult to detect the peeling of the glass substrate G by monitoring the DC voltage applied to the electrostatic adsorption electrode 32.
Hereinafter, a method for detecting peeling of the glass substrate G using the voltage monitor unit 5 and a reason why it becomes difficult to detect peeling due to the increase in size of the glass substrate G will be described.

First, considering the principle of electrostatic adsorption by the electrostatic adsorption electrode 32, the electrostatic adsorption electrode 32 and the glass substrate G form a capacitor arranged in parallel with the dielectric layer 31 interposed therebetween. There is. When a DC voltage is applied to the electrostatic adsorption electrode 32 from the positive electrode of the DC power supply 40, a positive charge is charged on the electrostatic adsorption electrode 32 side and a negative charge is charged on the glass substrate G side. Since the electrostatic adsorption electrode 32 and the glass substrate G are attracted to each other by electrostatic attraction due to these charges, the glass substrate G is adsorbed and held on the mounting table 3.

For example, when the glass substrate G is held in a horizontal position on the mounting table 3 as shown in FIG. 1, the area of the glass substrate G is S, and the distance between the glass substrate G and the electrostatic adsorption electrode 32 is d. Assuming that the charge between the glass substrate G and the electrostatic adsorption electrode 32 is Q, the voltage V applied between the mounting table 3 is represented by the following equation (1). Note that ε is the dielectric constant of the dielectric layer 31 between the glass substrate G and the electrostatic adsorption electrode 32.
V = Q × d / (ε × S)… (1)
Here, the peeling of the glass substrate G from the mounting table 3 occurs, and the increase in the average separation distance of the entire surface of the glass substrate G from the mounting table 3 is defined as Δd. In this case, the voltage V'between the mounting table 3 and the mounting table 3 can be expressed by the following equation (1)'.
V'= Q × (d + Δd) / (ε × S) ... (1)'
Therefore, by monitoring the voltage rise from the voltage V to V'with the voltage monitor unit 5, it is possible to detect the occurrence of peeling of the glass substrate G.

On the other hand, it is more likely that peeling will occur only in a part of the glass substrate G as schematically shown in FIG. 2 than the possibility that peeling will occur uniformly on the entire surface of the glass substrate G. I understood. Even if a part of the glass substrate G is peeled off, if the peeling occurs on the peripheral edge side of the glass substrate G as shown in FIG. 2, abnormal discharge due to plasma intrusion and damage to the surface of the mounting table 3 may occur. There is.

Therefore, the voltage change when a part of the glass substrate G is peeled off from the mounting table 3 will be considered. For example, when peeling from the mounting table 3 occurs in a part of the glass substrate G having an area S, the area of the peeling area is defined as p, and the increase in the average separation distance from the mounting table 3 is defined as Δd. At this time, as shown in FIG. 3, the glass substrate G in the region where peeling does not occur is the same as the glass substrate G held in a horizontal posture on the mounting table 3 at the separation distance d. Therefore, the glass substrate G in the region can be regarded as a capacitor having an area (Sp) and a separation distance of d.

On the other hand, the glass substrate G in the region separated from the mounting table 3 can be regarded as a capacitor having an area of p and a separation distance of (d + Δd). Since the value of Δd is very small, the dielectric constant of the space between the glass substrate G and the electrostatic adsorption electrode 32 in the peeling region is ignored, and the dielectric constant ε of the dielectric layer 31 is used.

Summarizing the states described above, as shown in FIG. 3, in the glass substrate G, the portion of the capacitor in the region peeled off from the mounting table 3 and the portion of the capacitor in the region not peeled off are connected in parallel to each other. It can be regarded as forming a part of the circuit.

C'can express the capacitance of the entire parallel circuit by the following equation (2).
C'= {ε × p / (d + Δd)} + {ε (S-p) / d} ... (2)
The voltage V + ΔV applied between the glass substrate G and the mounting table 3 when a part of the glass substrate G is peeled off is represented by the following equation (3). However, ΔV is the amount of change from the voltage of the equation (1).
V + ΔV = Q / C'... (3)

Since the charge Q between the glass substrate G and the electrostatic adsorption electrode 32 does not change before and after the peeling of the glass substrate G occurs, if Q is erased from the equations (1) and (3) and arranged, the glass substrate G is arranged. The voltage change ΔV before and after the peeling is expressed by the following equation (4). As described above, it can be seen that the voltage between the glass substrate G and the electrostatic adsorption electrode 32 changes according to the area where the glass substrate G is peeled off from the mounting table 3.
ΔV = p × Δd × V / {S × (d + Δd) −pΔd}… (4)

Here, the inventors have found that even when the area of the glass substrate G becomes large, the area where peeling occurs tends not to change significantly. On the other hand, even when the area of the glass substrate G becomes large, the glass substrate G can be adsorbed and held without changing the voltage applied from the DC power supply 40 represented by the equation (1). Looking at Eq. (4) based on these assumptions, if the area of the peeled portion p does not change even if the area S of the glass substrate G increases, the voltage when a part of the glass substrate G is peeled does not change. It can be seen that the amount of change tends to be small. Therefore, the amount of change in the measured voltage value detected by the voltage monitor unit 5 becomes small, and it becomes difficult to detect the peeling of the glass substrate G due to the change in voltage.

Therefore, in the plasma processing apparatus of the present disclosure, the voltage monitor unit 5 acquires a difference value corresponding to the difference between the voltage measured value and the voltage set value, and amplifies the difference value to peel off the glass substrate G. The detection accuracy is improved.

Hereinafter, the configuration of the voltage monitor unit 5 of this example will be described with reference to FIG. As shown in FIG. 1, the voltage monitor unit 5 is connected to, for example, a measurement portion D between the resistance 42 in the wiring 41 connecting the DC power supply 40 and the electrostatic adsorption electrode 32 and the resistance 40a. As shown in FIG. 4, the voltage monitor unit 5 is a difference between the voltage measurement unit 51 that acquires the voltage measurement value Vm at the measurement site D, the voltage measurement value Vm, and the voltage set value Vs input to the DC power supply 40. It includes a difference value acquisition unit 53 for acquiring a certain difference value Vd, and an amplification unit 54 for amplifying the difference value and acquiring the difference amplification value Va.

Further, 52 in FIG. 4 indicates a voltage level based on the voltage range (for example, 0 to 5 V) of the analog signal input to the DC power supply 40 corresponding to the voltage set value Vs, and is an analog signal output from the voltage measuring unit 51. This is a voltage level processing unit for processing a voltage level equal to the voltage level of the voltage measurement value Vm based on the voltage range (for example, 0 to 6 V).

As shown in FIG. 4, as the voltage level processing unit 52, for example, a non-inverting amplifier circuit using an operational amplifier 52a can be applied, and a signal corresponding to the voltage set value Vs is input to the positive side of the operational amplifier 52a. The output is configured to feed back to the negative side via the resistor R1. Further, the negative side of the operational amplifier 52a is grounded via the resistor R2. Then, the ratio of the resistance value of the resistor R1 and the resistance value of the resistor R2 is adjusted, the voltage set value Vs is amplified (in the case of each of the above-mentioned voltage ranges, it is amplified 1.2 times), and the processed voltage is applied. The set value Vs'is input to the difference value acquisition unit 53.

The difference value acquisition unit 53 can apply, for example, a differential amplifier circuit using an operational amplifier 53a. From the minus side, the processed voltage set value Vs'is input via the resistor R3, and from the plus side, the voltage measurement value Vm measured by the voltage measuring unit 51 is input via the resistor R5. Further, the positive side of the operational amplifier 53a is grounded via the resistor R6. Further, the output of the operational amplifier 53a is configured to feed back to the negative side via the resistor R4. As a result, the operational amplifier 53a acquires the difference value Vd between the voltage measurement value Vm and the processed voltage set value Vs'and outputs it to the amplification unit 54 in the subsequent stage.

Similarly, a non-inverting amplifier circuit provided with an operational amplifier 54a can be applied to the amplification unit 54, and a difference value Vd is input from the plus side, and its output is configured to be fed back to the minus side via the resistor R7. ing. Further, the negative side of the operational amplifier 54a is grounded via the resistor R8. Then, the amplification factor is set to be 10 times by adjusting the values of the resistance R7 and the resistance R8. The acquired differential amplification value Va is output to the control unit 9 described later.

For example, in the case of a glass substrate G having a long side of 1.85 m, a short side of 1.5 m, and an area of 2.78 m ² , which is called the 6th generation, the inventors have measured the result of measuring the DC voltage applied from the DC power supply 40. It is known that the peeling of the glass substrate G from the mounting table 3 can be detected by the technique directly used (for example, Patent Document 1: Japanese Patent Application Laid-Open No. 2016-174081). On the other hand, as the size of the glass substrate increases in the subsequent generations, it becomes difficult to detect the voltage change ΔV when partial peeling occurs as described above.

Further, as described above, even if the area of the glass substrate G becomes large, the area of partial peeling does not change significantly, and the amplification factor used in the amplification unit 54 (difference amplification value / difference value = amplification). Rate) can be set based on the following ideas.
Since the difference value is a voltage change value when the substrate is peeled off, it corresponds to ΔV represented by the equation (4). Here, assuming that V and d do not change significantly depending on the electrode size and p and Δd do not change in the equation (4), ΔV depends on the area of the glass substrate G and is approximately the area of the glass substrate G. The value is inversely proportional to. Therefore, for example, assuming that the glass substrate G having an area of 2.78 m ² is used as the reference size, the area S (m ² ) is relative to the difference value Vd ₀ obtained when the substrate peels off during the processing of the reference size substrate G. ), The difference value Vd _S acquired when the substrate peels off during the processing of the substrate G is approximately Vd _S = Vd ₀ × 2.78 / S. From this relationship as well, it can be confirmed that the difference value Vd _S becomes small when processing a substrate (S> 2.78 m ² ) larger than the reference size.
From this, in order to multiply the difference value Vd _S by the amplification factor to obtain the same sensitivity as Vd ₀ , the area of the glass substrate G to be subjected to plasma treatment with respect to the area of the glass substrate G of the reference size (2.78 m ² ). The area ratio of S (m ² ) (area ratio = S / 2.78) may be used as the amplification factor.

Further, when the area S of the glass substrate G is large and the amount of change in the voltage measurement value Vm acquired when the substrate peels off is small, the above-mentioned amplification factor (glass substrate G with respect to the reference size) is obtained with respect to the difference value Vd. Even if it is multiplied by the area ratio of), a sufficient difference value may not be obtained. In such a case, the area ratio may be multiplied by a correction value (1 to 10 times) and used as the amplification factor. For example, when the area ratio (= S / 2.78) described above is 3.6, setting the amplification factor to 10 times means that the correction value is set to about 2.8 times. ..
In this case, as the threshold value, a threshold value used when detecting the peeling of the substrate in the glass substrate G of the reference size can be set.
Further, the voltage monitoring unit 5 can directly output the voltage measured value Vm acquired by the voltage measuring unit 51 to the control unit 9, and directly monitors the DC voltage applied to the electrostatic adsorption electrode 32. You can also do it.

The plasma processing apparatus includes a control unit 9. The control unit 9 includes a program, a memory, and a CPU. The program incorporates an instruction (step group) to drive the plasma processing apparatus and execute the plasma processing of the glass substrate G. Further, the program incorporates an instruction to monitor the voltage and detect the detachment of the substrate G from the mounting table 3 according to the flowchart described later. The above-mentioned threshold value is stored in the memory of the control unit 9, and is used for comparison with the differential amplification value Va output from the amplification unit 54.

Further, as will be described later, the source power supply 72 is not stable at the start of operation of the plasma processing apparatus, and the measurement result of the DC voltage by the voltage monitor unit 5 may be affected by the stability. Therefore, in executing the detection of the detachment of the substrate G from the mounting table 3, the control unit 9 stores the determination reference value (variation range) of the fluctuation of the power values of the source power and the bias power generated at the start of operation. It is configured so that it can be determined whether or not the power value supplied from the source power source 72 is within a predetermined fluctuation range. Similarly, the fluctuation range of the bias power output from the bias power supply 75 is also stored so that it can be determined whether or not the power value supplied from the bias power supply 75 is within the fluctuation range of the bias power supply. It may be configured as.

Further, the control unit 9 outputs the voltage set value Vs to the DC power supply 40, outputs the DC voltage corresponding to the voltage set value Vs from the DC power supply 40, and outputs the voltage set value Vs to the voltage level processing unit 52. ..

Subsequently, the operation of the plasma processing apparatus will be described by taking an etching process on the glass substrate G as an example. First, the glass substrate G, which is the substrate to be processed, is mounted on the mounting table 3 by the cooperative action of the transport arm that has entered from the outside and the elevating pin (not shown). Next, after closing the gate valve 12, heat transfer gas is supplied between the mounting table 3 and the glass substrate G. Further, based on the information described in the processing recipe or the like, the control unit 9 inputs a voltage set value Vs for outputting a voltage value of 3000 V, for example, a signal having a voltage of 2.5 V to the DC power supply 40. As a result, a DC voltage of 3000 V is applied from the DC power supply 40 to the electrostatic adsorption electrode 32. As a result, the electrostatic adsorption electrode 32 and the glass substrate G are attracted to each other, and the glass substrate G is adsorbed and held on the mounting table 3. Next, a processing gas containing an etching gas such as CF ₄ or Cl ₂ is supplied into the processing container 10 from the shower head 2, and vacuum exhaust is performed from the exhaust port 13 to adjust the pressure in the processing container 10 to a predetermined pressure. ..

After that, the source power for plasma generation is applied from the source power source 72 to the inductively coupled antenna 70 via the matching unit 71 to generate a high frequency electric field between the mounting table 3 and the shower head 2. The processing gas supplied in the processing container 10 is excited by a high-frequency electric field generated between the mounting table 3 and the shower head 2, and plasma of the processing gas is generated. Further, by applying the bias power from the bias power source 75 to the susceptor 33, the ions contained in the plasma generated in the processing container 10 are attracted to the mounting table 3, and the film to be treated of the glass substrate G is etched. Is done.

FIG. 5 shows the power value of the source power, the power value of the bias power, the DC voltage of the measurement site D, and FIG. 6 when the glass substrate G is not peeled off from the mounting table 3. It is a graph which shows the time-dependent change of the differential amplification value. In this example, the source power supply 72 is turned on at time t1 and the source power is applied. Further, the bias power is applied at time t2. As shown in FIGS. 5 and 6, the power value of the source power (source power) and the power value of the bias power (bias power) repeatedly increase and decrease during the transition period until the set value stabilizes. After that, it is stable at a constant value (for convenience of illustration, the increase and decrease of the source power are shown for one cycle in the figure). Further, the voltage of the DC power supply (DC voltage) immediately after the source power supply 72 is turned on fluctuates slightly under the influence of fluctuations in the source power and bias power, and the differential amplification value also fluctuates accordingly. ..

Next, when the behavior of each electric power after stabilization is confirmed, peeling of the glass substrate G does not occur, and if the etching process is executed without any problem, each electric power remains stable at a constant value. .. However, for example, in the case where the glass substrate G is peeled off at time t4 in FIG. 6, the fluctuation occurs in the DC voltage on the electrostatic adsorption electrode 32 side. If this state continues, an abnormal discharge will occur (time t5), and the mounting table 3 may be damaged. Therefore, during the plasma processing, the peeling of the glass substrate G is monitored based on the differential amplification value Va acquired from the voltage monitor unit 5.

Next, the operation of monitoring the peeling of the glass substrate G will be described. FIG. 7 is a flowchart showing a group of steps for monitoring the peeling of the glass substrate G.
In performing the plasma processing as described above, the source power supply 72 is first turned on at time t1 and the application of the source power is started. Further, the bias power supply 75 is turned on at time t2, and the application of the bias power is started. After that, as shown in FIG. 7, the control unit 9 compares each measured value of the source power and the bias power with the fluctuation range, and determines whether or not the output of the source power and the bias power is stable (). Step S1). When it is determined that these electric powers are stable (step S1: Yes), it is confirmed that the DC voltage does not fluctuate due to the influence of fluctuations in the source power and the bias power. Then, for example, at time t3 shown in FIG. 6, the measurement of the DC voltage by the voltage measuring unit 51 is started, and the voltage measured value Vm is acquired (step S2).

After that, it is assumed that a part of the glass substrate G on the mounting table 3 is peeled off at time t4. As a result, as shown in FIG. 8A, it is assumed that the voltage between the glass substrate G and the electrostatic adsorption electrode 32 becomes, for example, 3020V. At this time, the voltage measurement unit 51 outputs the voltage measurement value Vm based on the voltage range of the analog signal (0 to 6V in this example) to the difference value acquisition unit 53. Since the measured voltage value is 3020V here, a signal having a voltage of, for example, 3.02V is output as the voltage measurement value Vm as shown in FIG. 8B.

On the other hand, as described above, the voltage range of the analog signal input as the voltage set value Vs is a signal of 0 to 5V. Therefore, the voltage level processing unit 52 aligns the voltage level of the voltage measured value Vm and the voltage level of the voltage set value Vs. Since the voltage set value Vs corresponding to 3000 V is a voltage of 2.5 V, this value is multiplied by 1.2 by the voltage level processing unit 52 and converted into a 3 V signal, and the difference value acquisition unit 53 is used. Entered.

In the difference value acquisition unit 53, the difference value Vd of the voltage measurement value Vm and the processed voltage set value Vs'is acquired (step S3). Here, since the measured voltage value Vm is 3.02 V and the processed voltage set value Vs'is 3 V, the difference value Vd is 0.02 V (FIG. 8 (c)).

Next, the difference value Vd acquired by the difference value acquisition unit 53 is input to the amplification unit 54 and amplified (step S4). In the present embodiment, since the amplification factor of the amplification unit 54 is 10 times, the differential amplification value Va is 0.2V as shown in FIG. 8D.

Next, the differential amplification value Va is output to the control unit 9, and the differential amplification value Va is compared with the threshold value (step S5). When the differential amplification value Va is within the threshold range, the differential amplification value Va is compared. Returning to the acquisition of the voltage measurement value Vm in order to update Va (step S5: No). When the differential amplification value Va exceeds the threshold value (step S5: Yes), a signal for stopping the power supply to the source power supply 72 and the bias power supply 75 is output (step S6). As a result, the application of the source power and the bias power is stopped (step S7), and the plasma processing in the processing container 10 is stopped. In step S6, only one of the source power supply 72 and the bias power supply 75 may be stopped. In particular, by stopping only one of the bias power supplies 75, it is possible to suppress the intrusion of plasma between the glass substrate G and the mounting table 3 while generating the plasma of the processing gas in the vacuum vessel 10. can.

Due to the above operation, even if the region where the peeling from the mounting table 3 occurs is a part of the glass substrate G, the DC voltage applied between the glass substrate G and the electrostatic adsorption electrode 32 is slightly increased. It is detected as the differential amplification value Va, and the plasma processing performed in the processing container 10 is stopped. As a result, it is possible to suppress the occurrence of abnormal discharge due to the peeling of the glass substrate G.

According to the above-described embodiment, in the plasma processing device for detecting the peeling of the glass substrate G from the mounting table 3, the voltage measurement value Vm and the voltage set value Vs'of the DC voltage applied to the electrostatic adsorption electrode 32 are used. The difference value Vd of the above is amplified and the difference amplification value Va is acquired. Then, the differential amplification value Va and the threshold value are compared, and when the differential amplification value Va exceeds the threshold value, a source that supplies high-frequency power into the vacuum vessel 10 for plasma processing on the substrate G. Stop applying power and bias power. Therefore, even when the glass substrate G becomes large and the change in the DC voltage becomes small, the peeling of the glass substrate G from the mounting table 3 is surely detected and the plasma processing on the substrate G in the processing container 10 is stopped. can do.

However, if the detection sensitivity becomes high, the DC voltage applied to the electrostatic adsorption electrode 32 may change due to the influence of fluctuations when the application of the source power and the bias power is started, and the source power supply 72 may be erroneously stopped. be. Therefore, after the application of the source power and the bias power is started and these powers are stabilized, the detection of the peeling of the substrate G from the mounting table 3 based on the differential amplification value Va is started. This makes it possible to prevent the above-mentioned erroneous stop from occurring.

Further, the influence of the fluctuation after starting the application of the source power and the bias power may affect the signal output to the control unit 9 as noise.
Therefore, in the above-described embodiment, the DC power supply 40, the voltage measuring unit 51, the difference value acquisition unit 53, and the amplification unit 54 are provided in the power supply unit 400, and the difference amplification value Va is output to the control unit 9. In this way, the power supply unit 400 outputs the difference value Vd to the control unit 9, for example, after amplifying the difference value Vd by 10 times, to the signal (difference amplification value) output to the control unit 9. The noise effect of can be suppressed to a small level.

Here, if the amplification factor for amplifying the difference value Vd is too large, noise or the like unrelated to the peeling of the glass substrate G may be detected and used for determining the stop of the source power and the bias power. .. On the other hand, if the amplification factor is too small, the peeling detection accuracy of the glass substrate G may decrease. Therefore, as described above, the amplification factor (difference amplification value / difference value = amplification factor) is the area of the reference size glass substrate G having an area of 2.78 m ² and the area S of the glass substrate G to be subjected to plasma treatment. It is preferable to use the area ratio (S / 2.78) with. Further, it is preferable to multiply by 1 to 10 times as a correction value. From these, the amplification factor is preferably about 5 to 25 times.

As discussed above, the embodiments disclosed this time should be considered to be exemplary and not restrictive in all respects. The above embodiments may be omitted, replaced or modified in various embodiments without departing from the scope of the appended claims and their gist.

3 Stand 9 Control unit 10 Processing container 31 Dielectric layer 32 Electrostatic adsorption electrode 40 DC power supply 51 Voltage measurement unit 53 Difference value acquisition unit 54 Amplification unit 70 Inductive coupling antenna 72 Source power supply 75 Bias power supply

Claims (6)

A mounting table provided in a vacuum vessel for performing plasma processing on the substrate and on which the substrate to be processed is placed, and
An electrostatic adsorption electrode that is placed in the dielectric layer provided on the above-mentioned pedestal and electrostatically adsorbs the substrate placed on the above-mentioned pedestal,
A DC power supply that applies a DC voltage corresponding to a preset voltage set value to the electrostatic adsorption electrode, and
A high-frequency power supply unit that generates high-frequency power for generating plasma of processing gas in the vacuum vessel and supplying it to the substrate, and a high-frequency power supply unit.
A voltage measuring unit that measures the DC voltage applied to the electrostatic adsorption electrode, and
A difference value acquisition unit that acquires a difference value corresponding to the difference between the measured value of the DC voltage measured by the voltage measurement unit and the voltage set value, and the difference value acquisition unit.
An amplification unit that amplifies the difference value acquired by the difference value acquisition unit and acquires the amplification value,
The amplification value is compared with a threshold value preset for the amplification value, and when the amplification value exceeds the threshold value, high-frequency power is supplied from the high-frequency power supply unit. It is equipped with a control unit that outputs a control signal for stopping.
The DC power supply, the voltage measuring unit, the difference value acquisition unit, and the amplification unit are provided in a common power supply unit.
The amplification value is output from the power supply unit to the control unit, and
A plasma processing apparatus characterized in that, in addition to the amplification value, a DC voltage measured by the voltage measuring unit is output from the power supply unit to the control unit . A mounting table provided in a vacuum vessel for performing plasma processing on the substrate and on which the substrate to be processed is placed, and
An electrostatic adsorption electrode that is placed in the dielectric layer provided on the above-mentioned pedestal and electrostatically adsorbs the substrate placed on the above-mentioned pedestal,
A DC power supply that applies a DC voltage corresponding to a preset voltage set value to the electrostatic adsorption electrode, and
A high-frequency power supply unit that generates high-frequency power for generating plasma of processing gas in the vacuum vessel and supplying it to the substrate, and a high-frequency power supply unit.
A voltage measuring unit that measures the DC voltage applied to the electrostatic adsorption electrode, and
A difference value acquisition unit that acquires a difference value corresponding to the difference between the measured value of the DC voltage measured by the voltage measurement unit and the voltage set value, and the difference value acquisition unit.
An amplification unit that amplifies the difference value acquired by the difference value acquisition unit and acquires the amplification value,
The amplification value is compared with a threshold value preset for the amplification value, and when the amplification value exceeds the threshold value, high-frequency power is supplied from the high-frequency power supply unit. It is equipped with a control unit that outputs a control signal for stopping.
The amplification unit obtains the amplification value by multiplying the difference value by a preset amplification factor.
The amplification factor is the area ratio (area ratio =) of the area S (m ² ) of the substrate on which the plasma treatment is performed to the area of the reference size substrate when the substrate having an area of 2.78 m ² is used as the reference size substrate. A plasma processing apparatus characterized in that it is set to a value obtained by multiplying S / 2.78) by 1 to 10 . The high-frequency power supply unit is a source power supply unit that supplies high-frequency power to a plasma forming unit for generating plasma of a processing gas in the vacuum vessel, and a processing generated by the plasma for the above-mentioned stand. A bias power supply unit for applying a bias power for drawing an active species of gas toward a substrate mounted on the mounting table is provided.
The control unit has a step of applying high frequency power from the source power supply unit to generate plasma in a vacuum vessel, then a step of applying bias power from the bias power supply unit to the above-mentioned table, and then. After the power values of the high-frequency power and the bias power are stabilized at the values within the preset fluctuation range, the step of starting the determination of stopping the supply of the high-frequency power using the amplified value and the step of executing the control signal are output. The plasma processing apparatus according to claim 1 or 2 . It is provided with a voltage level processing unit for aligning the voltage level based on the voltage range of the analog signal input as the voltage set value and the voltage level based on the voltage range of the analog signal output as the voltage measurement value. The plasma processing apparatus according to any one of claims 1 to 3 , wherein the plasma processing apparatus is characterized. The process of placing the substrate to be processed on a mounting table provided in a vacuum container for performing plasma processing on the substrate, and
A DC voltage corresponding to a preset voltage set value is output to the electrostatic adsorption electrode arranged in the dielectric layer provided on the above-mentioned pedestal, and the substrate mounted on the above-mentioned pedestal is statically charged. The process of electrostatic adsorption and
The process of generating plasma of the processing gas in the vacuum vessel and supplying high-frequency power to supply it to the substrate, and
The step of measuring the DC voltage applied to the electrostatic adsorption electrode and
A step of acquiring a difference value corresponding to a difference between the measured value of the DC voltage and the voltage set value, and
The step of amplifying the difference value and acquiring the amplified value, and
A step of comparing the amplification value with a threshold value preset for the amplification value and stopping the supply of the high frequency power when the amplification value exceeds the threshold value. Including,
In the step of acquiring the amplification value, the amplification value is calculated by multiplying the difference value by the amplification factor, and the amplification value is plasma-processed when a substrate having an area of 2.78 m ² is used as a reference substrate. A plasma processing method characterized in that the ratio (ratio = S / 2.78) of the area S (m ² ) of the substrate to be performed is set to a value obtained by multiplying the ratio (ratio = S / 2.78) by 1 to 10 . The step of supplying high-frequency power to generate the plasma is a step of supplying high-frequency power to the plasma forming portion for generating plasma of the processing gas in the vacuum vessel, and then to the above-mentioned stand. , A step of applying a bias power for drawing the active species of the processing gas generated by the plasma toward the substrate mounted on the mounting table.
The plasma processing method according to claim 5 , wherein the determination of stopping the supply of high-frequency power using the amplification value is performed after the step of applying the bias power.

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