JP2007258636A - Dry-etching method and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dry etching method and its device for preventing the damage of a substrate to be etched by extracting a substrate to be etched from an electrostatic chuck, and removing any residual absorption for the substrate to be etched before shfiting to a conveyance process. <P>SOLUTION: The end section of a substrate 1 to be etched is finely projected, and a portion of the substrate 1 to be etched is made to float for carrying out plasma processing. Thus it is possible to remove any residual charge, and to reduce the residual absorption force of the substrate 1 to be etched. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic chuck for attracting and holding, for example, a semiconductor wafer or a substrate to be etched such as a substrate having a high dielectric constant, etc., and a dry etching method for removing the substrate to be etched from the electrostatic chuck. And a dry etching apparatus for the same.

  Conventionally, a thin plate removing method in this type of dry etching method has a structure as shown in FIG. FIG. 4 is an explanatory diagram of a conventional separation method. The prior art will be described with reference to FIG.

  An electrostatic chuck 3 is provided on the upper surface of the mounting table 5, a pair of electrodes 4 is provided in the electrostatic chuck 3, and the electrodes 4 are constituted by a power source 15 and a switch 16. On the other hand, the lift pins 19 are connected to the lift table 20, and when the lift table moves up and down, a plurality of lift pins (generally 3 to 4) move up and down at the same time.

  For example, the substrate to be etched carried into the processing chamber is placed on the electrostatic chuck 3, and the switch 16 is turned on and a DC voltage is applied by the power source 15, so that the substrate is subjected to Coulomb force or Johnson-Rahbek force. An electrostatic attractive force is generated between the etching substrate 1 and the electrostatic chuck 3, and the substrate to be etched is attracted and held on the electrostatic chuck 3. In order to take out the substrate 1 to be etched after the plasma etching process is performed, the switch 16 is turned off to cancel the application of the DC voltage. When the residual charge is large, for example, plasma is applied to the substrate to be etched to neutralize the charge, and then the lift table 20 is lifted to lift the lift pin 19 from the upper surface of the electrostatic chuck to float the substrate 1 to be etched, The method of unloading the substrate 1 to be etched by 21 has been taken.

As prior art document information relating to this application, for example, Patent Document 1 is known.
JP-A-6-252253

  However, when the wafer to be etched is thermally oxidized, the thin film formed on the substrate to be etched, or the like is a high dielectric constant material, the residual adsorption force becomes considerably large. Further, in recent years, the thickness of the substrate to be etched has been reduced, and when the lift pins 19 are pushed up, the substrate to be etched is damaged, and the substrate to be etched cannot be taken out.

  The present invention is to solve the above-mentioned problems, and removes the substrate to be etched from the electrostatic chuck and removes the residual adsorption to the substrate to be etched before moving to the transfer process, thereby preventing the substrate to be etched from being damaged. It is an object of the present invention to provide a dry etching method and a dry etching apparatus for taking out a wafer.

  In order to achieve the above object, the present invention has the following configuration.

  The invention described in claim 1 of the present invention particularly includes the step of releasing the application of the chucking voltage of the electrostatic chuck during plasma processing, and the direction of the substrate to be etched away from the electrostatic chuck with respect to the substrate to be etched. A process of pushing up a part of the pushing member up to the lower surface of the substrate to be etched by a small protrusion amount, and further pushing up the substrate to be etched to the delivery position by the pushing member and delivering it from the electrostatic chuck to the delivery means. As a result, a part of the substrate to be etched is lifted, the residual charge on the back surface is removed by the plasma, and when it is pushed up to the delivery position, the residual adsorption force becomes weak and the substrate to be etched can be easily detached. Have

  The invention according to the second aspect of the present invention particularly includes the step of releasing the application of the chucking voltage of the electrostatic chuck, and a part of the substrate to be etched in a direction away from the electrostatic chuck with respect to the substrate to be etched. The step of pushing the pushing member up to the bottom surface of the substrate to be etched by the protruding amount, the step of pushing up the minute protruding amount by the pushing member and then generating plasma, and further pushing the substrate to be etched to the delivery position by the pushing member It has a configuration in which it is transferred from the electric chuck to the transfer means, so that a part of the substrate to be etched is lifted, the residual charge on the back surface is removed by the plasma, and the residual adsorption force is weakened when pushing up to the transfer position. It has the effect of.

  In the invention according to claim 3 of the present invention, in particular, after pushing up one side of the substrate to be etched by a small amount to weaken the residual charge on the back surface, the pushing member is lowered and placed on the electrostatic chuck, and then the opposite The push-up member on the side is pushed up to a minute amount to further weaken the residual charge on the back surface, and then pushed up to the transfer position by the push-up member and transferred from the electrostatic chuck to the transfer means. Since the portion where the residual charge is removed is enlarged, there is an effect that the residual attracting force is weaker when pushing up to the delivery position.

  The invention described in claim 4 of the present invention has a configuration in which the step of pushing up a minute amount is repeated a plurality of times alternately on each side, and the amount of pushing up is sequentially increased. Since the portion where the residual charge is removed is further enlarged, there is an effect that the residual attracting force becomes weaker when pushing up to the delivery position.

  The invention according to claim 5 of the present invention is particularly independent of an electrostatic chuck capable of electrostatically attracting the substrate to be etched, and a push-up member that slightly projects a part of the substrate to be etched on the electrostatic chuck. A push-up member that slightly protrudes on the opposite side that can be operated, a push-up member that can push up the substrate to be etched to the delivery position, and means for removing charges by plasma during the push-out As a result, the residual stress of the substrate is reduced each time a minute amount is pushed up, and the thin plate substrate can be taken out without being damaged.

  The dry etching method and apparatus using the thin plate release method of the present invention are configured to slightly float a part of the substrate to be etched and irradiate the plasma, and slightly float from the electrostatic chuck and irradiate the plasma. There is an effect that the residual adsorptive force to the substrate to be etched can be removed before the process is started.

  Hereinafter, the first aspect of the present invention will be described with reference to the drawings.

  Note that the same components and the like as those described in the background art are assigned the same reference numerals and detailed description thereof is omitted.

  FIG. 1 is a schematic cross-sectional view of an apparatus according to Embodiment 1 of the present invention.

  In FIG. 1, the electrostatic chuck 3 is provided on the upper surface of the mounting table 5, is installed inside the processing chamber 26, and is configured to be moved up and down.

  A pair of electrodes are embedded in the electrostatic chuck, and are inserted into the mounting table 5 and electrically connected to one end side of the power supply line. A DC power supply 15 is connected via a switch 16 on the lower side.

  The mounting table 5 is provided with, for example, four lift pins 7 and 10 serving as push-up members. As for these lift pins, two lift pins 7 and two lift pins 10 are attached to respective lift bases as shown in FIG. The lift table 8 can be moved up and down by a motor 9 and the lift table 11 can be moved up and down by a motor 12. Further, the motors 9 and 12 are attached to a lift base 13 and can be moved up and down by an air cylinder 14.

Next, the overall configuration of the apparatus will be described. A high frequency power of 36.56 MHz is applied from the high frequency power supply 30 into the plasma chamber 25 on the upper side of the processing chamber 26, and is applied to the antenna 28 via the matching circuit 29. On the other hand, CF ₄ gas is introduced from the halogen gas supply device 22 for plasma gas from the upper part of the plasma chamber 25. Alternatively, Ar gas may be introduced from the inert gas supply device 23 and plasma gas such as O ₂ gas may be introduced from the oxygen gas supply device 24 to form a mixed gas. Thus, the plasma chamber 25 is configured to generate plasma.

  Further, vacuum pumps 34 and 35 for evacuating the processing chamber 26 and an orifice valve 33 for controlling the gas pressure when plasma gas is flowed are provided. Furthermore, a gate valve 27 for carrying in and out the substrate to be etched is provided, and a transfer arm 21 for transferring the substrate 1 to be etched from a transfer chamber (not shown) can be moved in and out.

Next, an embodiment of the present invention will be described taking an ICP plasma apparatus as an example. The substrate 1 to be etched is transferred from the transfer chamber onto the mounting table 5 by the transfer arm 21 serving as transfer means. In this delivery, the lift base 13 is lifted by the air cylinder 14 and the lift pins 7 and 10 are lifted via the lift bases 8 and 11 to receive the substrate 1 to be etched. Next, the lift pins 7 and 10, which the transport arm 21 has returned and raised, lowers the lift base 13 by the air cylinder 14, thereby lowering the upper surface of the electrostatic chuck 3. As a result, the substrate 1 to be etched is placed on the electrostatic chuck 3. At this time, the switch 16 is turned on to apply an attracting voltage to the electrode 4 of the electrostatic chuck 3 and electrostatically attracts it. Then, in order to enhance the cooling effect of the substrate 1 to be etched, a coolant 18 at 10 ° C. is supplied, and further, He gas 17 is supplied. Thereafter, the mounting table 5 is raised to a predetermined process position, CF ₄ gas is introduced from the halogen gas supply device 22, and Ar gas is introduced from the inert gas supply device 23 to the plasma chamber 25. And the substrate 1 to be etched is dry-etched. When the etching process is completed, the high frequency power supply 30 is turned off, the CF ₄ gas and Ar gas are stopped, the orifice valve 33 is fully opened, the inside of the processing chamber 26 is evacuated, and the etching gas is exhausted. When a predetermined degree of vacuum is reached, Ar gas is introduced from the inert gas supply device 23, the gas pressure is controlled by the orifice valve 33, and then power is applied by the high frequency power source 30 to generate plasma for static elimination. Subsequently, the electrostatic chuck 3 that holds the substrate 1 to be etched in this plasma atmosphere is released (the application of the suction voltage is released), and the lift table 8 is raised by the motor 9 so that the lift pins 7 are smaller than the surface of the electrostatic chuck. The protrusion is made to protrude by, for example, 0.5 mm. FIG. 2A is a diagram for explaining this state. When the lift pin 7 protrudes by a minute protrusion amount, the edge of the substrate 1 to be etched is lifted because the edge is weak even if the electrostatic attracting force due to the residual charge remains on the substrate 1 to be etched. At this time, the most part still remains attracted to the electrostatic chuck by the residual attracting force. Plasma flows into this floating gap and residual charges are removed. When the predetermined time has elapsed, the lift pin 7 is once lowered, then the lift base 11 is raised by the motor 12, and the other lift pin 10 is made to project a minute protrusion amount, for example, 0.5 mm as described above. FIG. 2B is a diagram for explaining this situation. The action is the same as that of removing the charge by operating the lift pin 7.

  Here, when the residual stress is small, the thin plate substrate is not damaged only by the one-side operation of the operation. However, when the residual stress is large and the electrostatic adsorption force is large, it is necessary to gradually increase the static elimination area, so both operations are performed. Furthermore, the electrostatic attraction force can be further reduced by repeating these multiple times. Here, the minute protrusion amount when pushing up the lift pin is 0.5 mm, but this may be any amount that does not break even if the substrate to be etched is locally pushed up and curved, It depends on the outer size, thickness, elastic modulus, etc. of the substrate 1 to be etched.

  After performing the static elimination process in this manner, the supply of Ar gas is stopped and the high frequency power supply 30 is turned off to stop the plasma. Next, after making the heights of the lift pins 7 and 10 the same, the lift base 13 is raised by the air cylinder 14, and the substrate 1 to be etched is lifted by the lift pins 7 and 10. Next, the transfer arm 21 serving as a transfer means is inserted between the lift pins 7, 10, the lift pins 7, 10 are lowered, and the substrate 1 to be etched which has been detached from the electrostatic chuck 3 is transferred to the transfer arm 21 and transferred to the transfer chamber. Is done. FIG. 2C illustrates this operation.

  As described above, in the present embodiment, after the application of the chucking power of the electrostatic chuck 3 is canceled, the lift pins 7 and 10 are not pushed up at a stretch by the protruding position corresponding to the delivery position of the substrate 1 to be etched, but the substrate 1 to be etched 1 In order to prevent the substrate 1 from being broken, the lifted pins 7 and 10 partly float, the residual charge is gradually neutralized by the plasma, the residual adsorption force is reduced, and the protrusion is projected to the delivery position. Absent. Note that plasma may be generated before the lift pins 7 and 10 float.

  In addition, when the residual adsorption force is weakened by repeating the lift pins 7 and 10 a plurality of times and pushing up several times, the number of repetitions is reduced by increasing the push-up amount stepwise by 0.5 mm, and the substrate to be etched can be smoothly done. Can be taken out. Of course, the protruding amount of the lift pins in stages is not limited to 0.5 mm.

  In the present embodiment, a method using lift pins has been described. However, for example, a method of handling a peripheral portion of a substrate may be used without using lift pins. The apparatus to which the present invention is applied is not limited to the ICP plasma apparatus, but can be applied to a CCP plasma apparatus, an ECR plasma apparatus, a helicon wave plasma apparatus, and the like.

  A dry etching method using the thin substrate removal method and the dry etching apparatus according to the present invention are configured such that a part of a substrate to be etched is slightly floated and irradiated with plasma, and is slightly floated from an electrostatic chuck and irradiated with plasma. It has the effect of removing the residual adsorption force to the substrate to be etched before moving to the transfer process, and is used to adsorb and hold a substrate to be etched such as a semiconductor wafer or a substrate having a high dielectric constant. The electric chuck is useful for applications such as a dry etching method and a dry etching apparatus having a thin plate substrate removing step of taking out the substrate to be etched from the electrostatic chuck.

Schematic cross-sectional view of an apparatus according to Embodiment 1 of the present invention (A) A cross-sectional view showing a state of being slightly protruded by a lift pin, (b) a cross-sectional view showing a state of being slightly protruded by a lift pin, (c) a cross-sectional view showing a state of being slightly protruded by a lift pin Plan view showing the arrangement of lift pins (A) Cross-sectional view showing conventional lift pin operation, (b) Cross-sectional view showing conventional lift pin operation

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate to be etched 2 Guide ring 3 Electrostatic chuck 4 Electrode 5 Mounting table 6 Insulator 7 Lift pin 8 Lift table 9 Motor 10 Lift pin 11 Lift table 12 Motor 13 Lift base 14 Air cylinder 15 DC power supply 16 Switch 17 He gas 18 Refrigerant 19 Lift pin 20 Lift base 21 Transfer arm 22 Halogen gas supply device 23 Inert gas supply device 24 Oxygen gas supply device 25 Plasma chamber 26 Processing chamber 27 Gate valve 28 Antenna 29 Matching circuit 30 High frequency power supply 31 Matching circuit 32 Bias power supply 33 Orifice valve 34 Vacuum pump 35 Vacuum pump

Claims (5)

In a dry etching method for dry etching a substrate to be etched electrostatically adsorbed on an electrostatic chuck,
Release the voltage application of the electrostatic chuck that holds the substrate to be etched in the plasma atmosphere after the dry etching process,
The substrate to be etched is pushed up by a minute protrusion amount by a push-up member, and after a predetermined time has passed, the substrate to be etched is pushed up to the delivery means by the push-up member and delivered to the delivery means, and the substrate to be etched after dry etching is electrostatically A dry etching method characterized in that it is released from the chuck. In a dry etching method for dry etching a substrate to be etched electrostatically adsorbed on an electrostatic chuck,
Release the voltage application of the electrostatic chuck holding the substrate to be etched after the dry etching process,
The above-mentioned substrate to be etched is pushed up by a minute protruding amount by a pushing-up member to generate plasma,
Further, a dry etching method characterized in that the substrate to be etched is pushed up to a delivery means by a push-up member, delivered to the delivery means, and the substrate to be etched after dry etching is detached from the electrostatic chuck. The process of pushing up the minute amount pushes up one side of the substrate to be etched to weaken the residual charge on the back surface, then lowers the pushing member, places it on the electrostatic chuck, and then moves the pushing member on the opposite side to the minute amount. 3. The method according to claim 1, further comprising a step of pushing up to further weaken the residual charge on the back surface, pushing up to a transfer position by a push-up member, and transferring from the electrostatic chuck to the transfer means. The dry etching method as described. The dry etching method according to claim 1, wherein the step of pushing up the minute amount is alternately repeated a plurality of times for each side, and the amount of pushing up is sequentially increased. A dry etching apparatus for performing a plasma dry etching process on a substrate to be etched in a predetermined atmosphere, and an electrostatic chuck capable of electrostatically attracting the substrate to be etched, and a part of the substrate to be etched on the electrostatic chuck protruding slightly A push-up member that projects a part of the opposite side that can be operated independently, and a push-up member that can push up the substrate to be etched to the delivery position, and removing the charge by plasma at the time of the push-out A dry etching apparatus.

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