JPH07263531A - Plasma processing apparatus having a mechanism for separating a substrate to be electrostatically adsorbed and a method for separating a substrate to be electrostatically adsorbed to be processed - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a plasma processing apparatus and a method for separating a substrate to be processed, which is provided with a mechanism capable of quickly, reliably and safely separating the substrate to be processed from the electrostatic adsorption electrode. In a plasma processing apparatus provided with an electrostatic adsorption clamp mechanism, a lift pin 9 capable of projecting from an electrostatic adsorption electrode surface into a vacuum chamber 10 and air, a rare gas, an inorganic gas, or nitrogen, oxygen, hydrogen, sulfur, It has a mechanism 1 for introducing one or more mixed gases of gases containing at least one of chlorine or fluorine atoms, and has pressure control systems 7, 7a, 7b for maintaining the pressure of the mixed gases at a predetermined pressure. It is a device. When the substrate 5 to be processed is detached, the lift pin 9 applies a detaching force, and the pressure of the mixed gas is maintained at a predetermined pressure (0.1 to 500 Pa).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus applied to a semiconductor manufacturing apparatus or the like. More specifically, the present invention relates to a plasma processing apparatus having a mechanism capable of quickly, reliably and safely detaching a substrate to be processed from an electrostatic attraction electrode and a method of detaching the substrate to be processed.

[0002]

2. Description of the Related Art In a plasma processing apparatus for processing the surface of a substrate to be processed such as a semiconductor wafer under reduced pressure, the heat received by the substrate to be processed is efficiently removed from the plasma, and the temperature of the substrate to be processed is irreversible. In order to prevent damage, it is necessary to provide a temperature control mechanism for preventing the temperature of the electrode supporting the substrate to be processed from rising and a means for increasing the efficiency of heat conduction between the substrate to be processed and the electrode. As means for increasing the efficiency of heat conduction between the substrate to be processed and the electrodes, a mechanical clamping mechanism for mechanically applying force to the electrode from above the substrate to be fixed, which is called a mechanical clamp mechanism, or a dielectric on the electrode is used. A substrate to be processed is placed, and a DC voltage is applied between the electrode and the substrate to be processed, or a self-bias voltage induced on the substrate to be processed by plasma is used to fix the substrate by electrostatic attraction. There is known a method of narrowing the distance between the substrate to be processed and the electrode to increase the contact area, and a method of generating convection by filling the gap between the substrate to be processed and the electrode with a gas such as He in addition to these mechanisms. Has been.

However, recently, the size of the substrate to be processed tends to be large, and the demand for expansion of the effective use area of the substrate is increasing. Therefore, in the mechanical clamp, a smaller and smaller number of clamping claws are provided on the edge of the substrate. The substrate must be pressed against the electrode by using it close to the plate, the substrate will be distorted, and if the gas is used together to improve the heat conduction between the substrate to be processed and the electrode, set the gas pressure to the desired value. There was an inconvenience such as being unable to hold it. Further, there is a problem that particles are likely to be generated due to mechanical contact between the claw for clamping and the substrate to be processed, peeling of the reaction product attached to the claw for clamping, and the like.

On the other hand, the method of fixing the substrate to be processed by electrostatic attraction can fix the substrate to be processed with uniform force over the entire surface without disturbing the plasma, and is essentially suitable for a large substrate to be processed. It is a fixed method.

However, when the electrostatic adsorption clamp mechanism is used, the adsorption force is reduced even after the plasma processing is completed due to the potential difference caused by the residual charges in the dielectric substance interposed between the substrate to be processed and the electrostatic adsorption electrode. Therefore, it is difficult to remove the substrate to be processed quickly, reliably and safely.

Conventionally, there are roughly the following two types of methods for removing the electrostatically attracted substrate to be processed.

(1) Detachment mechanism by mechanical means (1-1) A method of causing a mechanical detachment force applying means such as a pin or a piston to protrude from the surface of the electrostatic attraction electrode. (1-2) A method in which a high-pressure gas is introduced into the gap between the substrate to be processed and the electrostatic adsorption electrode from an introduction tube provided inside the electrostatic adsorption electrode, and the desorption force is imparted by the expansive force of the gas pressure. (2) Detachment mechanism by electric means (2-1) By reversing the polarity of the voltage applied to the electrostatic attraction electrode and the substrate to be processed, the residual charge of the insulator interposed between the two is erased and the attraction force is increased. How to eliminate it. (2-2) A method in which the potential of the electrostatic attraction electrode and the substrate to be processed are set to the ground potential to eliminate the attraction force. (2-3) In the case where the substrate to be processed is a semiconductor wafer, a method in which the DC voltage is set to zero in the presence of plasma and the residual charges are eliminated through the plasma.

[0008]

However, each of the above-mentioned various conventional techniques has the following problems in principle or in practical use.

(1) Problems due to forced disengagement by mechanical means (1-1) The method of causing a mechanical disengagement force imparting means such as a pin or a piston capable of protruding from the surface of the electrostatic adsorption electrode is caused by residual charge. A force for detaching a part of the substrate to be processed is forcibly applied in a state where the suction force uniformly acts on the entire surface of the substrate to be processed. Therefore, there is a high possibility that the portion to which the force is applied may deform or break the substrate to be processed. (1-2) Further, there is a problem that particles are generated due to contact friction between the mechanical separation mechanism and the substrate to be processed. (1-3) When the substrate to be processed is separated by the expansion force of gas pressure, if the substrate to be processed is a light substrate such as a silicon wafer, the wafer is blown up at the moment of separation, and significantly There was a point of failure.

(2) Problems of Eliminating Residual Charge by Electrical Means (2-1) When erasing the residual charge in the insulator by reversing the polarity of the applied voltage, the residual charge is eliminated only once. It is practically difficult to set the state to the completely erased state without excess or deficiency. In order to overcome this, it was inevitable that the polarity of the applied voltage was repeatedly inverted, the value was gradually decreased, and finally the value was made zero. Therefore, if only the polarity reversal method is used, it takes a long time of several tens of seconds or more to perform separation. (2-2) A method of grounding both the electrostatic attraction electrode and the substrate to be processed is as follows.
When the SiO ₂ film is present, the time constant until completely eliminating the residual charges of the dielectric film is very large, which is not practical. (2-3) A method in which the DC voltage is set to zero in the presence of plasma and the residual charge is eliminated through the plasma is as follows.
Due to the decrease in the attraction force, the heat conduction between the substrate to be processed and the electrostatic attraction electrode may be deteriorated, and the temperature of the substrate to be processed may rise. In addition, if the DC voltage is set to zero and the time during which the plasma is present is set improperly, a large amount of residual charge remains or the substrate is recharged due to self-bias generated on the substrate to be processed, and the adsorption force is sufficiently increased. I can't lower it.

The present invention, which has been made in view of the above problems, provides a plasma processing apparatus and a method for removing a substrate to be processed, which is provided with a mechanism capable of quickly, reliably and safely removing the substrate to be processed from the electrostatic attraction electrode. It is intended to be provided.

[0012]

In order to solve the above-mentioned problems, the present invention places a substrate to be processed on an electrode via a dielectric, and a static electricity caused by a DC potential difference between the electrode and the substrate to be processed. In a plasma processing apparatus equipped with an electrostatic adsorption clamp mechanism for fixing a substrate to be processed by electroadsorption and performing processing of the substrate to be processed under reduced pressure, an electrostatic adsorption electrode is placed in a chamber where the substrate to be processed is detached. A mechanical releasing force applying means such as a pin or a piston capable of projecting from the surface, and at least one of air, a rare gas, an inorganic gas or nitrogen, oxygen, hydrogen, sulfur, chlorine or a fluorine atom.
A gas introduction mechanism for supplying a mixed gas containing seeds to the periphery of the substrate to be processed, and a pressure control system for maintaining the pressure in the chamber where the substrate to be processed is released at a predetermined pressure. It is characterized by that.

It is desirable from the standpoint of automation of operation to further include a sequencer for the mechanical releasing force applying means, the gas introduction mechanism and the pressure control system.

It is preferable that the mechanical separating force applying means is provided at a position in the attraction surface of the electrostatic attraction electrode, which is opposed to a portion other than the edge portion of the substrate to be processed. The mechanical separating force applying means is composed of, for example, a plurality of pins provided at the suction surface along the circumference at regular intervals so as to be capable of projecting and retracting. Further, as another example, it is configured by a circular base provided in the suction surface so as to be flush with the suction surface so as to be retractable.

Further, preferably, the mechanical releasing force applying means is provided with a drive mechanism for adjusting the height of the pin or the circular base protruding from the suction surface.

Further, the method of releasing the electrostatically adsorbed substrate to be processed is a method of releasing the substrate to be processed which is fixed to the electrostatic adsorption electrode by electrostatic adsorption in the plasma processing apparatus as described above. There is a detaching force applied to the substrate to be processed by using a mechanical detaching force imparting means such as a pin or a piston capable of protruding from the attraction surface of the electrostatic attraction electrode,
It is characterized in that a predetermined pressure atmosphere of air, a rare gas, an inorganic gas or a mixed gas containing at least one of nitrogen, oxygen, hydrogen, sulfur, chlorine or fluorine atoms is maintained in the vicinity of the substrate to be processed.

Further, by forming a minute gap between the substrate to be processed fixed to the electrode by electrostatic attraction and the attraction surface of the electrostatic attraction electrode, the substrate to be treated and the electrostatic attraction by the formation of the minute gap. Gas that increases the potential difference between the electrodes and exists in the atmosphere around the substrate to be processed (hereinafter referred to as "atmosphere gas")
Is used as a discharge gas to generate a discharge near the substrate to be processed. The gas particles charged by the discharge neutralize the charged substrate to be processed. Then, after the static elimination, the substrate to be processed is separated from the electrostatic attraction electrode.

In order to generate an electric discharge in the vicinity of the substrate to be processed, the fine gap is set so that the potential difference between the substrate to be processed and the electrostatic adsorption electrode becomes equal to or higher than the discharge start voltage, and further according to Passen's law, The pressure of the atmosphere gas is set. There are cases where the pressure is set after setting the fine gap, and cases where the fine gap is set after setting the pressure.

The interval of the fine gap is preferably set to about 0.1 mm or more and about 1 mm or less.

It is preferable that the pressure of the atmospheric gas is set to 0.1 Pa to 500 Pa within the range of the fine gap.

The potential difference between the substrate to be processed and the electrostatic attraction electrode is proportional to the interval of the minute gap. The discharge generated in the vicinity of the substrate to be processed is DC discharge.

After the discharge, when the potential difference between the substrate to be treated and the electrostatic attraction electrode becomes equal to or lower than the discharge sustaining potential, the substrate to be treated is separated from the electrostatic attraction electrode. For example, when the surface potential of an 8-inch substrate to be processed becomes 220 V or less, the substrate to be processed is separated from the electrostatic attraction electrode.

The atmosphere gas preferably has a flow rate of 200.
Nitrogen gas is introduced at a sccm pressure of 20 Pa.

Alternatively, the atmospheric gas is a gas for processing the substrate to be processed. For example, the gas for processing the substrate to be processed is CF ₄ + O ₂ or CF ₄ + CHF ₃ .

In order to form a fine gap between the substrate to be processed and the electrostatic attraction electrode, the pin projects from the surface of the electrostatic attraction electrode.

The height of this pin is adjusted to such a level that the substrate to be processed is not damaged. Preferably, the pin height is
It is set to about 0.1 mm or more and about 1 mm or less.

[0027]

In the present invention, the generation of DC discharge in the vicinity of the substrate to be processed plays the most important role. The gas molecules charged by this DC discharge neutralize the charged substrate to be processed.

The conditions for generating this DC discharge are the potential difference Φ _{s of} the substrate to be processed with respect to the ground, the distance D between the grounded component near the substrate to be processed, such as the counter electrode or the wall of the vacuum container and the substrate to be processed, and the object to be processed. It is determined by the pressure P of the gas existing around the processing substrate. More specifically, the potential difference Φ _{s of the} substrate to be processed with respect to the earth is the Passen's law (or the Passen curve (Paschen's curve)).
('S law)), the product of pressure and distance (P *
Discharge start voltage (Vs = f (P * D)) determined by D)
When Φ _s ≧ Vs or more (Φ _s ≧ Vs), a DC discharge occurs between the substrate to be processed and a grounded component near the substrate.

Further, according to the present invention, the potential difference between the substrate to be processed and the electrostatic attraction electrode is increased by the distance (fine gap) between the charged substrate to be treated and the electrostatic attraction electrode, and DC discharge is generated. Play an important role in making it happen.
The phenomenon that the potential difference increases can be theoretically explained as follows. The potential difference V = Φ _s between the potential difference Φ _{s of the} substrate to be ground and the potential difference Φ _d of the electrostatic attraction electrode.
-Φ _d has a relationship of V = Q / C (a) with the electric quantity Q of the residual charge of the substrate to be processed. Here, C represents capacitance. On the other hand, the capacitance C is represented by C = εS / d (b). Here, ε is the dielectric constant between the substrate to be processed and the electrostatic attraction electrode, S is the area of the substrate to be treated, and d is the interval (fine gap) between the substrate to be processed and the electrostatic attraction electrode. By substituting the equation (b) into the equation (a), it becomes V = Qd / εS = kd (c) (k is a constant). Here, the electric quantity of the residual charge of the substrate to be processed does not decrease unless the substrate to be processed is grounded.
Q can be regarded as constant. Since ε can be regarded as a constant and S can be regarded as constant, after all, the potential difference V between the substrate to be processed and the electrostatic attraction electrode is proportional to the distance d (see FIG. 3) between the substrate to be processed and the electrostatic attraction electrode. I can say. Therefore, when the distance d between the substrate to be processed and the electrostatic attraction electrode is increased, the potential difference V between the substrate to be processed and the electrostatic attraction electrode becomes large.

Further, the widening of the distance d between the substrate to be processed and the electrostatic attraction electrode means that the potential difference Φ _{s of the} substrate to be processed with respect to the ground becomes large. Electric field E (= V / d = Q / εS = generated from residual charge Q of the electrostatic adsorption electrode)
It can be said that the constant value increases as the distance d between the substrate to be processed and the electrostatic attraction electrode increases. E = V / (D−d) (d) (D is considered to be the distance between the wall surface of the vacuum container and the adsorption surface of the electrostatic adsorption electrode.) Substituting the equation (c), E = kd / This is because (D-d) (e). It can also be said that the potential difference Φ _s of the substrate to be processed with respect to the ground increases as the potential difference V increases.

From the above viewpoints, for example, when the pins are pushed up from the attraction surface of the electrostatic attraction electrode to lift the substrate to be processed, the potential difference Φ _{s of the} substrate to be processed with respect to the ground is increased during the process of lifting the substrate to be processed. The discharge start voltage Vs determined by the distance D between the processing substrate and some grounded component near the processing substrate (for example, the distance between the processing substrate and the counter electrode) and the pressure P of the atmospheric gas around the processing substrate. Reach At that time, it can be said that DC discharge occurs between the substrate to be processed and the components near the substrate to be processed. Where the discharge occurs near the substrate to be processed is that the substrate to be processed is grounded in the vicinity of the substrate to be processed during the process of raising the substrate to be processed (potential difference V, that is, the process of increasing the potential Φ _{s of the} substrate). Of the spaces between the parts, it first occurs in a space that has an atmosphere according to Passen's law.

However, the distance between the substrate to be processed and the electrode for electrostatic attraction cannot be expanded indefinitely. This is because if the distance between the substrate to be processed and the electrostatic attraction electrode is increased, the substrate to be processed will be deformed or destroyed. In order to widen the space, it is necessary to apply a larger force for separation. When a large force is partially applied while the attracting force due to the residual charge acts evenly on the entire surface of the substrate to be processed,
The substrate to be processed is easily bent or broken at the portion to which the force is applied. Therefore, the distance between the substrate to be processed and the electrostatic attraction electrode must be set so that the substrate to be processed is not deformed or destroyed. It is best to separate the substrate to be processed and the electrostatic adsorption electrode to the extent that a minute gap is formed between the substrate to be processed and the electrostatic adsorption electrode. The detachment mechanism that implements this substrate detachment method includes a drive mechanism that adjusts the protrusion height of the pins to the extent that a fine gap is formed between the substrate to be processed and the electrostatic attraction electrode without damaging the substrate to be processed. It is desirable to be prepared.
Further, the pins must be arranged so as to be lifted at a portion other than the edge portion of the substrate to be processed. The inventors
This is because it was found from the substrate detachment experiment that the edge of the substrate to be processed was chipped or the substrate to be processed tilted up when the edge of the substrate to be processed was lifted.

Since the distance between the substrate to be processed and the electrostatic attraction electrode can be set only to the extent that a minute gap is formed, it can be said that the increase in the potential difference of the substrate to be processed has an upper limit. It may be practically difficult to control the generation of DC discharge by adjusting the distance between the substrate to be processed and the electrostatic attraction electrode, that is, only the potential of the substrate to be processed. In such a case, in order to control the generation of the DC discharge, according to Passen's law,
It can be said that it is easiest to control the pressure of the gas existing around the substrate to be processed. The gas existing around the substrate to be processed may be any gas as long as it can form an atmosphere in which DC discharge is generated near the substrate to be processed. For example, it may be a processing gas such as a mixed gas containing at least one of nitrogen, oxygen, hydrogen, sulfur, chlorine or fluorine atoms, a residual gas left after the substrate processing, or a purge gas for expelling the residual gas. . From the viewpoint of controlling the gas pressure, it is best to use the gas introduced into the vacuum vessel, that is, the processing gas or the purge gas.

The inventors have found that, regardless of the voltage applied to the electrostatic attraction electrode for electrostatic attraction, when the distance between the 8-inch semiconductor wafer and the electrostatic attraction electrode is about 0.1 mm, the potential difference of the wafer with respect to the ground is about. 4,000V, about 40mm at about 1mm,
It was found to be 000V. Further, it was discovered that when the pressure of N ₂ gas was set from 0.1 Pa to 500 Pa within this potential difference range, DC discharge occurred. As will be described later, the inventors were able to separate the substrate to be processed within 10 seconds within this pressure range. Moreover, even when the residual charge of the substrate to be processed is not completely lost, if the surface potential of the substrate to be processed is lower than the discharge sustaining potential, the substrate to be processed is gradually lifted up by the pin to gradually remove the electrostatic adsorption electrode. The substrate to be processed could be separated from the suction surface. The inventors have found that the surface potential of an 8-inch semiconductor wafer is 220
Even if 2,500 semiconductor wafers are continuously separated under the condition that they are separated from the electrostatic attraction electrode when reaching V,
It was confirmed that the semiconductor wafer could be separated accurately without damage. Table 1 shows that after applying a DC voltage of −1000 V to the electrostatic adsorption electrode in the reactive ion etching apparatus to etch the semiconductor wafer fixed on the adsorption surface of the electrostatic adsorption electrode, the substrate is divided into three types by the following three methods. Shows the surface potential of the substrate when it is released. After applying DC voltage,
(1) Nitrogen gas is introduced into the vacuum container where the wafer is placed at the moment when the pins are ejected from the adsorption surface of the electrostatic adsorption electrode to lift the semiconductor wafer, and the semiconductor wafer is electrostatically adsorbed while the pressure is kept at 20 Pa. Method of detaching from the electrode,
(2) A method in which the pressure inside the vacuum container is 0.05 Pa, the semiconductor wafer is forcibly detached from the electrostatic attraction electrode only by lifting the semiconductor wafer by the pin, and (3) before the semiconductor wafer is lifted by the pin, the semiconductor Nitrogen gas was introduced into the vacuum container in which the wafer was placed, the pressure was set to 20 Pa, and after leaving it for 1 minute, the nitrogen gas was exhausted, and then the semiconductor wafer was lifted with a (0.05 Pa) pin to separate it from the electrode. The method is a comparison of the surface potentials of semiconductor wafers. In each case, the position of the semiconductor wafer at the time of measuring the surface potential is 10 mm from the attraction surface of the electrostatic attraction electrode. Here, the surface potential of the semiconductor wafer is the electrostatic measurement surface potential meter model 344 (TREK Inc. Electrostatic voltmeter
del 344). Incidentally, after the application of the DC voltage was stopped, the surface potential of the semiconductor wafer with the semiconductor wafer still mounted on the electrostatic attraction electrode was 370V.

[0035]

[Table 1]

The surface potential of the semiconductor wafer separated by the method (1) is much smaller than the surface potential of the semiconductor wafer separated by the methods (2) and (3). This means that the amount of static electricity charged on the semiconductor wafer is considerably lost due to the occurrence of DC discharge in the vicinity of the semiconductor wafer. Perhaps, from the distance between the semiconductor wafer and the electrostatic attraction electrode and the pressure of nitrogen gas, the semiconductor wafer and the grounded component,
For example, it can be inferred that discharge is occurring between the counter electrode and the wall surface of the vacuum container. Then, it is shown that the gas molecules charged by the discharge have discharged the charged semiconductor wafer. It can be said that a considerable amount of static electricity remains on the semiconductor wafer from the surface potential of the semiconductor wafer separated by the method (2). The surface potential of the semiconductor wafer separated by the method (3) is almost the same as the surface potential by the method (2). This indicates that the charge of the charged semiconductor wafer cannot be sufficiently removed by simply introducing and discharging the gas in the vacuum container. The surface potential of the semiconductor wafer separated by the methods (2) and (3) is the surface potential (37) of the semiconductor wafer while it is mounted on the electrostatic adsorption electrode.
0 V) and lower than the potential expected from the equation (c). This can be said to be the effect of stray capacitance.

From these results, when the semiconductor wafer is separated from the electrostatic attraction electrode, the vacuum container is filled or filled with gas (atmosphere gas) so that the vicinity of the substrate to be processed has an atmosphere for generating discharge. Can be said to be important. Therefore, it is desirable that the substrate detaching mechanism for carrying out the detaching method of the present invention is provided with a sequencer for sequentially operating the introduction of the atmospheric gas, the protrusion of the pins, and the pressure adjustment.

Table 2 shows that after etching the semiconductor wafer fixed by applying a DC voltage of -1000 V to the electrostatic adsorption electrode in the reactive ion etching apparatus, the nitrogen gas was lifted at the moment when the semiconductor wafer was lifted by the pins. Is introduced into the chamber in which the semiconductor wafer is placed,
(1) 0.05Pa, (2) 0.1Pa, (3) 10P
a, (4) 50 Pa, (5) 500 Pa, (6) 600
It shows the time required for the surface potential to reach 100 V or less when the vacuum container is filled with a pressure of Pa. The height of the pin protruding from the attraction surface of the electrostatic attraction electrode was about 0.1 mm to about 1 mm.

[0039]

[Table 2]

The pressure is 0.1 to 500 Pa, and both are 1
It reached 100V or less within 0 seconds. That is, the distance between the substrate to be processed and the electrostatic attraction electrode is about 0.1 mm to about 1 m.
It is shown that discharge of atmospheric gas (N ₂ gas) occurred between the semiconductor wafer and the electrostatic adsorption electrode within a pressure range of 0.1 to 500 Pa under m.

[0041]

1 is a block diagram of the first embodiment of the present invention.
In the figure, 1 is a gas pipe for introducing gas into the vacuum chamber 10, 2 is an electrostatic attraction electrode, 3 is a dielectric sheet covering the surface of the electrostatic attraction electrode 2, and 4 is a direct current to the electrostatic attraction electrode 2. Direct current power source for applying voltage, 5 substrate to be processed for performing ion etching, 6 electrode holder, 7 automatic pressure control mechanism (Auto Pressure Controller), 7a flow control valve, 7b exhaust system (The figure shows an example constituted by a turbo molecular pump and a rotary pump.), 8 is a plasma source, and 9 is a lift pin embedded in the electrostatic attraction electrode 2. The lift pin 9 is adapted to project and retract from the surface of the dielectric sheet 3 when the drive member 13a is moved up and down via the drive shaft 13 supported by the bearings 11a and 11b.
A frame 12 is provided with a drive mechanism (not shown) for moving the drive member 13a up and down.

In FIG. 1, when etching the substrate 5 to be processed, the substrate 5 to be processed is placed on the electrostatic attraction electrode 2 via the dielectric sheet 3 using a transporting means (not shown), and then a DC power source is used. A DC voltage is applied to the electrostatic attraction electrode 2 from 4. At the same time, a gas pipe 1 for introducing gas into the vacuum chamber 10
Chlorine gas is further introduced, and a predetermined pressure (about 0.5 Pa) is set by the automatic pressure control mechanism 7. Then, the plasma source 8
To generate plasma. A direct current circuit including the electrostatic attraction electrode 2 and the direct current power source 4 is formed by the plasma, the target substrate 5 is fixed to the electrostatic attracting electrode 2, and the surface of the target substrate 5 is etched. After completion of the treatment, nitrogen gas was introduced from the gas pipe 1, the pressure control (about 2 Pa) was performed by the automatic pressure control mechanism 7, the plasma source 8 and the DC power supply 4 were turned off, and the gas was buried in the electrostatic adsorption electrode 2. Lift pin 9 from the surface of dielectric sheet 3 by 0.5 m
Protrude about m. When the substrate 5 to be processed begins to separate from the electrostatic attraction electrode 2, the lift pins 9 are further projected to completely separate the substrate 5 to be processed. The time required from the start of the protrusion of the lift pin 9 to the completion of the separation was about 3 seconds.

FIG. 2 is a block diagram of a second embodiment of the present invention, more specifically, a block diagram when the present invention is applied to a parallel plate type reactive ion etching (RIE) apparatus. Reference numeral 14 is a high frequency power source, 15 is a ground electrode, and the other parts have the same structure as the embodiment of FIG.

In FIG. 2, when the substrate 5 to be processed is processed, the substrate 5 to be processed is placed on the electrostatic attraction electrode 2 via the dielectric film 3 by using a transfer means (not shown), and then the DC power source 4 is used. Further, a DC voltage is applied to the electrostatic attraction electrode 2. At the same time, the process gas (CF ₄ + O ₂ ) is introduced into the vacuum chamber 10 from the gas pipe 1 which constitutes the gas introduction system, and the automatic pressure control mechanism 7 brings the process gas to a predetermined pressure (about 10 Pa). Then
A high frequency power is supplied from the high frequency power supply 14 to the electrostatic attraction electrode 2 to generate a reactive gas plasma between the electrostatic attraction electrode 2 and the ground electrode 15. A direct current circuit including the electrostatic attraction electrode 2 and the direct current power supply 4 is formed by the plasma, and the substrate 5 to be processed is fixed to the electrostatic attraction electrode 2 and the substrate 5 to be processed 5
The surface of is etched. After the processing is completed, the process gas is continuously introduced through the gas pipe 1, and the high-frequency power source 14 and the direct-current power source 4 are turned off while the pressure control (about 10 Pa) is performed by the automatic pressure control mechanism, and the electrostatic attraction electrode 2
The lift pins 9 embedded inside are projected from the surface of the dielectric sheet 3 by about 0.5 mm. When the substrate 5 to be processed begins to separate from the electrostatic attraction electrode 2, the lift pins 9 are further projected to completely separate the substrate 5 to be processed. In this case, the time required from the start of the protrusion of the lift pin 9 to the completion of the separation was about 2 seconds.

After the etching process is completed, the gas to be introduced is switched to argon and the pressure in the vacuum chamber 10 is set to 10 P.
When the same detaching operation as described above was performed in the state of being maintained at a, the time from the start of protrusion of the lift pins 9 to the completion of detachment could be about 1 second.

In each of the above embodiments, the vacuum chamber 10 is shared by the chamber constituting the processing portion of the substrate 5 to be processed and the chamber for separating the substrate to be processed. Alternatively, the substrate 5 to be processed may be transferred together with the electrode 2 to another chamber where the detaching operation is performed, and the detaching operation may be performed in this part.

Further, the gas pipe 1 has a common system for introducing the process gas and a system for introducing the gas to be introduced when the substrate 5 to be processed is separated, but they may be separate systems. Furthermore, the gas introduction system introduced at the time of separation can be made common with the air or nitrogen gas introduction system provided for venting the chamber. When the process gas and the gas at the time of desorption are different as in the first embodiment, the operability may be improved by using separate introduction systems.

FIG. 3 shows a block diagram of the third embodiment. For details, see Multi-chamber Etching System (ANELVA-
4100) is a diagram of a substrate release mechanism incorporated in a chamber (vacuum container) modularized for the parallel plate reactive etching process of FIG. Similar to the above-described embodiment, 1 is a pipe for introducing gas into the vacuum chamber 10, 1a and 1b are valves, 20 is an etching gas supply source, and 21 is an atmosphere gas supply source. 2 is an electrostatic adsorption electrode, 3 is an electrostatic adsorption electrode 2
The dielectric sheet covering the surface of the substrate constitutes the attracting surface of the substrate. Reference numeral 4 is a DC power source for applying a DC voltage to the electrostatic attraction electrode 2, 5 is an 8-inch semiconductor wafer (substrate to be processed), 6 is a holder, 14 is a high frequency power source, and 15 is a ground electrode. 7 is an automatic pressure control mechanism.
ller), 7a is an exhaust valve, and 7b is an exhaust system composed of a turbo molecular pump and a rotary pump.
The automatic pressure control mechanism 7 adjusts the degree of opening of the valve 7a to adjust the pressure inside the vacuum container. Reference numeral 9 denotes a lift pin installed in the electrostatic attraction electrode 2. The semiconductor wafer 5 is lifted by the four lift pins, and constitutes a means for applying a mechanical detaching force to the substrate to be processed. As shown in FIG. 4, the four lift pins are provided at equal intervals on the circumference of a circle shorter than the diameter of the semiconductor wafer 5 (the same applies to the first and second embodiments). The lift pin 9 is connected to a drive shaft 13 supported by bearings 11a and 11b, and is configured to project and retract from the surface of the dielectric sheet 3 when the drive member 13a moves up and down. 12 is a vacuum tank 1
A drive mechanism 22 for raising and lowering the drive member 13a is installed on the frame installed at the bottom of 0. The drive mechanism 22 has a configuration in which the height of the lift pin 9 protruding from the suction surface when the fine gap is formed between the semiconductor wafer 5 and the electrostatic suction electrode 2 is adjusted to a height that does not damage the semiconductor wafer 5. is there. Specifically, the protruding height of the lift pin 9 can be adjusted to about 0.1 mm to 1 mm. 23
Indicates a sequencer. The sequencer 23 is a valve 1
The opening and closing of a, 1b, the activation of the automatic pressure control mechanism 7 and the activation of the drive mechanism 23 are controlled.

The substrate detaching operation using the substrate detaching mechanism incorporated in the chamber modularized for the parallel plate type reactive etching process will be described.

The semiconductor wafer 5 is placed on the attraction surface made of the dielectric sheet 3 covering the electrostatic attraction electrode 2 by using a transfer robot (not shown). Next, a DC voltage (for example, −1000 V) is applied to the electrostatic attraction electrode 2 from the DC power supply 4.
The valve 1a is opened, and the etching gas (CF ₄ + O ₂ ) is introduced into the vacuum chamber 10 through the pipe 1. The pressure of the etching gas is set to about 10 Pa by the automatic pressure control mechanism 7. Then, high frequency power is supplied from the high frequency power supply 14 to the electrostatic attraction electrode 2 to generate reactive plasma between the electrostatic attraction electrode 2 and the ground electrode 15. A direct current circuit including the electrostatic attraction electrode 2 and the direct current power source 4 is formed by the plasma, the semiconductor wafer 5 is fixed to the electrostatic attraction electrode 2, and the surface of the semiconductor wafer 5 is etched. After the elapse of a predetermined time, the high frequency power supply 14 and the direct current power supply 4 are turned off to end the etching process. Valve 1 continues after processing
Etching gas CF from gas pipe 1 with a open
While introducing ₄ + O ₂ (90/10 sccm),
The counter 23 activates the drive mechanism to cause the lift pin 9 embedded in the electrostatic attraction electrode 2 to protrude from the surface of the dielectric sheet 3 by about 0.5 mm. On the other hand, Sequencer 2
3 activates the automatic pressure control mechanism 7 to set the pressure of the etching gas to about 10 Pa. When the semiconductor wafer 5 starts to separate from the electrostatic attraction electrode 2 as a result of the static elimination action by the discharge, the lift pins 9 are further projected to make the semiconductor wafer 5
To leave completely. In this case, it took about 2 seconds from the start of the protrusion of the lift pin 9 to the completion of the separation. Also in this example,
As in the second embodiment, an etching gas is used as an atmosphere gas for generating a discharge between the semiconductor wafer 5 and the electrostatic attraction electrode 2 at the time of separation.

As a fourth embodiment, in the mechanism of FIG.
CF ₄ + CHF for both etching gas and atmosphere gas
₃ (150/50 sccm) was used. When the pressure of the atmospheric gas was set to 20 Pa and the same detaching operation as in the third embodiment was performed, it took about 1 second from the start of the protrusion of the lift pin 9 to the completion of the detachment.

As a fifth embodiment, after the etching process in the third embodiment is completed, the valve 1a is closed by the sequencer 23, and then the valve 1b is opened to supply the argon gas (atmosphere gas) (200 sccm) to the vacuum container. Introduced in 10. Simultaneously with the introduction, the sequencer 23 activates the drive mechanism to cause the lift pin 9 to project by about 0.5 mm. On the other hand, the sequencer 23 activated the automatic pressure control mechanism 7 to set the pressure of the argon gas to about 10 Pa. It took about 1 second from the start of the protrusion of the lift pin 9 to the completion of the separation.

As a sixth embodiment, after completion of the etching treatment in the third embodiment, N ₂ (200 sc
cm) was used. When the pressure of the atmospheric gas was set to 20 Pa and the same detaching operation as in the third embodiment was performed, it took about 1 second from the start of protrusion of the lift pin 9 to the completion of detachment.

As a seventh embodiment, ANELVA-4100
The substrate detaching operation by the substrate detaching mechanism incorporated in the chamber (the helicon wave plasma generator is mounted) that is modularized for the helicon wave etching process will be described. Here, the substrate separating mechanism is exactly the same as the substrate separating mechanism incorporated in the chamber modularized for the parallel plate type reactive etching process in FIG. A helicon wave plasma generator is disclosed in US Pat. No. 4,990,2.
29 and 5,122,251. Chlorine gas is introduced into the chamber as an etching gas and helicon wave plasma is generated to perform the etching process. The helicon wave plasma generator and the DC power supply 4 are turned off, and the process is terminated. Then, nitrogen gas (200 sccm) is introduced into the chamber as an atmosphere gas, and the pressure is set to about 2 Pa by the automatic pressure control mechanism 7. At the same time, the lift pin 9 embedded in the electrostatic attraction electrode 2 is attached to the dielectric sheet 3
About 0.5 mm from the surface. Semiconductor wafer 5
When the wafer starts to separate from the electrode 2, the lift pin 9 is further projected to completely separate the semiconductor wafer 5. The time required from the start of the protrusion of the lift pin 9 to the completion of the separation is about 3
It was seconds.

The gas filled at the time of separation may be air. In this case, a vent valve (not shown) separately provided in the vacuum container (chamber) 10 is opened to introduce air into the chamber.

In each of the above embodiments, the case of the plasma etching process is explained, but the substrate detaching mechanism of the present invention is also incorporated in the plasma CVD device, the sputtering device and the plasma ashing device which electrostatically attract the substrate to be processed. The plasma processing apparatus can be configured and the detachment method of the present invention can be implemented. Also, in each example,
After setting the pressure of the gas existing in the atmosphere around the substrate to be processed (semiconductor wafer), a small gap, that is, the space between the substrate to be processed and the electrostatic attraction electrode was formed. It is also possible to adjust the pressure of the atmospheric gas to the discharge starting pressure.

FIG. 5 shows another embodiment of the mechanical separating force applying means, in which a circular base 24 is provided at the center of the dielectric sheet 3 constituting the suction surface. The circular base 24 is the drive shaft 1
It is connected to 3 so that it can be projected and retracted, and the upper surface thereof is flush with the suction surface when retracted. This round table 24
The mechanical separation force imparting means by means of can also form a fine gap between the substrate to be processed and the suction surface, and the substrate to be processed can be separated in the same manner as in the above-mentioned embodiment.

The case where the pressure of the gas introduced at the time of detaching the substrate 5 to be processed is 2 Pa, 10 Pa, and 20 Pa has been described, but in the range of approximately 0.1 Pa to 500 Pa, a practically sufficient residual charge disappearing effect is obtained. Obtainable.
The higher the pressure is, the faster the disappearance speed is, and the effect of shortening the detachment time is obtained. However, when the pressure is too high, the effect of disappearing the residual charge is reduced again.

[0059]

As described above, according to the present invention, in an apparatus for processing a substrate to be processed by fixing the substrate to be processed to the electrode by electrostatic adsorption under reduced pressure, the electrostatic adsorption electrode The effect is that the substrate to be processed can be quickly and easily removed from the substrate. In addition, it is possible to avoid damage to the substrate caused by the residual electrostatic attraction force.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a third embodiment of the present invention.

FIG. 4 is a top view showing an arrangement relationship of pins that constitute a mechanical separating force applying unit.

FIG. 5 is a partial cross-sectional view of another embodiment of the mechanical releasing force applying means.

[Explanation of symbols]

 1 Gas Pipe 2 Electrostatic Adsorption Electrode 3 Dielectric Sheet 4 DC Power Supply 5 Substrate 6 Electrode Holder 7 Automatic Pressure Control Mechanism 7a Flow Control Valve 7b Exhaust System 8 Plasma Source 9 Lift Pin 10 Vacuum Tank 11a, 11b Bearing 12 Frame 13 Drive Axis 13a Drive member 14 High frequency power supply 15 Ground electrode 20 Etching gas supply source 21 Atmosphere gas supply source 22 Drive mechanism 23 Sequencer 24 Circular platform

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/3065 // H05H 1/46 M 9014-2G

Claims (24)

[Claims] 1. An electrostatic attraction clamp mechanism for placing a substrate to be processed on an electrode via a dielectric and fixing the substrate to be processed by electrostatic attraction due to a DC potential difference between the electrode and the substrate to be processed. In a plasma processing apparatus for processing a substrate to be processed under reduced pressure, a chamber for performing the operation of separating the substrate to be processed is provided with a mechanical separating force applying means such as a pin or a piston capable of projecting from the electrostatic attraction electrode surface. ,
The substrate to be processed is provided with a gas introduction mechanism for supplying air, a rare gas, an inorganic gas or a mixed gas containing at least one of nitrogen, oxygen, hydrogen, sulfur, chlorine or fluorine atoms to the periphery of the substrate to be processed. A plasma processing apparatus comprising a pressure control system for maintaining the pressure in the chamber in which the detachment operation is performed at a predetermined pressure. 2. The plasma processing apparatus according to claim 1, further comprising a sequencer for the mechanical release force applying means, the gas introduction mechanism, and the pressure control system. 3. Fixing by electrostatic attraction is performed by applying a DC voltage applied between an electrode and a substrate to be processed or a substrate to be processed by plasma generated in a vacuum chamber in which the electrode and the substrate to be processed are placed. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is electrostatically attracted and fixed by a potential difference generated by self-bias. 4. The plasma processing apparatus according to claim 1, wherein the gas introduction mechanism is common or separate from the process gas introduction mechanism of the plasma processing for processing the substrate to be processed. 5. The plasma processing apparatus according to claim 1, wherein the mechanical separating force applying means is provided at a position other than the edge portion of the substrate to be processed within the attraction surface of the electrostatic attraction electrode. 6. The mechanical releasing force applying means comprises a plurality of pins provided so as to project and retract at equal intervals along the circumference of the attraction surface of the electrostatic attraction electrode. Plasma processing equipment. 7. The plasma processing according to claim 1 or 2, wherein the mechanical separating force applying means is constituted by a circular base provided in the attraction surface of the electrostatic attraction electrode so as to be flush with the attraction surface so as to be retractable. apparatus. 8. The plasma processing apparatus according to claim 6, wherein the mechanical separating force applying means has a drive mechanism for adjusting a height of the pin or the circular base protruding from the suction surface. 9. A method of releasing a substrate to be processed fixed to an electrostatic attraction electrode by electrostatic attraction, comprising a machine such as a pin or a piston capable of protruding from the attraction surface of the electrostatic attraction electrode to the substrate to be processed. The release force is applied by using the selective release force application means, and in the vicinity of the substrate to be processed, air, rare gas,
A method for separating a substrate to be processed, characterized in that a predetermined pressure atmosphere of an inorganic gas or a gas containing at least one of nitrogen, oxygen, hydrogen, sulfur, chlorine or fluorine atoms is maintained. 10. A method of separating a substrate to be processed electrostatically attracted to an electrostatic attraction electrode, comprising forming a fine gap between the substrate to be processed and the attraction surface of the electrostatic attraction electrode,
A method for separating a substrate to be processed, comprising: discharging a substrate in the vicinity of the substrate to be processed, and then separating the substrate from the electrostatic attraction electrode. 11. The method for separating a substrate to be processed according to claim 10, wherein the fine gap is formed after the pressure of the gas existing in the atmosphere around the substrate is set to a predetermined pressure. 12. The method for separating a substrate to be processed according to claim 10, wherein the pressure of the gas existing in the atmosphere around the substrate to be processed is set to a predetermined pressure after forming the fine gap. 13. The fine gap formed between the substrate to be processed and the suction surface is a fine gap of about 0.1 mm to about 1 mm.
13. The method for separating a substrate to be processed according to any one of 0 to 12. 14. The method for separating a substrate to be processed according to claim 9, wherein the pressure of the gas existing in the atmosphere around the substrate to be processed is set to a pressure of 0.1 Pa to 500 Pa. 15. The method for separating a substrate to be processed according to claim 9, wherein the discharge generated between the substrate to be processed and the electrostatic attraction electrode is a DC discharge. 16. The separation of the substrate to be processed from the electrostatic attraction electrode is performed when the potential difference between the substrate to be processed and the electrostatic attraction electrode becomes equal to or lower than a potential required to maintain discharge. 16. The method for separating a substrate to be processed according to any one of 9 to 15. 17. The method for detaching a substrate to be processed according to claim 16, wherein the substrate to be processed is separated from the electrostatic attraction electrode when the surface potential of the substrate to be processed having a diameter of 8 inches becomes 220 V or less. 18. The method for separating a substrate to be processed according to claim 9, wherein nitrogen gas is introduced into the atmosphere around the substrate to be processed at a flow rate of 200 sccm and the pressure is set to 20 Pa. 19. The separation of the substrate to be processed according to claim 9, wherein the gas existing in the atmosphere around the substrate to be processed is a gas for processing the substrate to be processed before the separation of the substrate to be processed. Method. 20. A gas for processing a substrate to be processed is CF ₄
The method for separating a substrate to be processed according to claim 19, wherein the mixed gas of gas and O ₂ gas is used. 21. The gas for processing the substrate to be processed is CF ₄
The method for separating a substrate to be processed according to claim 19, wherein the mixed gas of gas and CHF ₃ gas is used. 22. The fine gap is formed by projecting a pin or a circular base from the suction surface toward the substrate.
3. The method for separating a substrate to be processed according to any one of 2 above. 23. The method for separating a substrate to be processed according to claim 22, wherein the projecting height of the pin or the circular base is such a height that the substrate is not damaged. 24. The protruding height of the pin or the circular base is about 0.
The method for separating a substrate to be processed according to claim 23, wherein the height is from 1 mm to about 1 mm.