JP2005051098A - Device and method for plasma treating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treating device for carrying out a plasma treatment of a substrate attracted and held by electrostatic power on an electrostatic stage, by improving the attraction of the substrate with the electrostatic stage, and preventing plasma treatment failures such as etching failures generated due to the shortage of an attraction power. <P>SOLUTION: This plasma treating device equipped with an electrostatic stage for attracting a substrate by electrostatic power is provided with a control means for dividing the plasma discharge into a first plasma discharge for charging the back face of the substrate, and a second plasma discharge for plasma-treating the surface of the substrate to generate a plasma. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  Conventionally, a plasma etching apparatus which is one of dry etching apparatuses is widely known as a plasma processing apparatus.

  As an example of the plasma etching apparatus, there is one in which an electrostatic adsorption stage is provided in a vacuum chamber. In such a plasma etching apparatus, a substrate (wafer) to be processed is adsorbed and held on the electrostatic adsorption stage. The processing gas supplied into the vacuum chamber is turned into plasma, and the substrate is etched by this plasma.

  The electrostatic adsorption stage generates a static electricity between the substrate and the surface of the insulating member by applying a DC voltage to an electrode embedded in the insulating member located in the upper layer of the stage, and the substrate is made using this static electricity. Is provided with a so-called electrostatic chuck mechanism (see, for example, Patent Document 1).

As a means for fixing the substrate to the substrate support, a mechanical chuck mechanism that clamps the outer peripheral portion of the substrate is also conceivable. However, the electrostatic chuck mechanism that attracts the back surface of the substrate and the electrostatic adsorption stage with electrostatic force. Can be said to be advantageous in preventing the generation of particles as compared with a mechanical chuck mechanism in which the clamp and the substrate are in direct physical contact.
JP-A-10-27780

  However, in the conventional plasma processing apparatus in which the substrate is sucked and fixed using the electrostatic chucking stage described above to perform the plasma processing, the substrate may not be sufficiently sucked, which hinders processing such as plasma etching. There was a thing.

  In particular, in a manufacturing process of a TFT (Thin Film Transistor) using a quartz substrate, a conductive film is formed on the back surface of the quartz substrate in advance for electrostatic chucking, but the thickness of the conductive film is insufficient. In such a case, the attracting force becomes insufficient, and the contact between the substrate and the electrostatic attracting stage is lowered, which may cause various etching defects.

  That is, due to insufficient contact between the substrate and the electrostatic adsorption stage, the substrate is warped, or the temperature control of the substrate heated via the heater provided on the electrostatic adsorption stage varies, resulting in uniform etching. There is a risk that the performance may be reduced, or the bias voltage on the substrate surface may be non-uniform, resulting in variations in etching amount.

  In addition, in the case of a process with a short etching time, such a defect tends to be prominent because etching is terminated while the adhesion between the substrate and the electrostatic adsorption stage is unstable.

  It is an object of the present invention to provide a plasma processing apparatus and a plasma processing method that can solve the above-described problems.

  According to the first aspect of the present invention, in the plasma processing apparatus provided with the electrostatic adsorption stage for adsorbing the substrate by electrostatic force, the first plasma discharge for charging the back surface of the substrate and the surface of the substrate being plasma Control means for generating plasma by dividing it into a second plasma discharge for processing is provided.

  In the present invention according to claim 2, the control means adsorbs the substrate on the electrostatic adsorption stage by electrostatic force, executes the first plasma discharge, and terminates the first plasma discharge. Thereafter, control was performed so as to execute the second plasma discharge after a predetermined time.

  According to a third aspect of the present invention, in the plasma processing method of storing a substrate in a vacuum chamber and performing plasma processing in a state where the substrate is adsorbed on an electrostatic adsorption stage by electrostatic force, the back surface of the substrate is charged. The first plasma discharge is performed for a predetermined time, and after the first plasma discharge is temporarily terminated, the plasma processing is performed on the surface of the substrate by executing the second plasma discharge for plasma processing after the predetermined time has elapsed. It was decided.

  According to a fourth aspect of the present invention, in the plasma processing method according to the third aspect, the substrate is adsorbed on the electrostatic adsorption stage by electrostatic force, and the first plasma discharge is performed. After the plasma discharge was finished, a second plasma discharge was performed after a predetermined time to perform plasma treatment on the substrate.

  (1) In the present invention described in claim 1, in the plasma processing apparatus provided with the electrostatic adsorption stage for adsorbing the substrate by electrostatic force, the first plasma discharge for charging the back surface of the substrate, Since the control means for generating plasma by dividing the surface into the second plasma discharge for plasma processing is provided, the adhesion force due to electrostatic force is instantly generated between the substrate and the electrostatic adsorption stage. Even if it is a short etching process, the contact property is improved and uniform etching can be performed, and no etching residue or the like occurs in the substrate surface. And the plasma processing apparatus which shows this effect can be provided simply, without adding a special structure.

  (2) In the present invention according to claim 2, the control means adsorbs the substrate on the electrostatic adsorption stage by electrostatic force, and executes the first plasma discharge, and the first plasma discharge. Since the second plasma discharge is controlled to be executed after a predetermined time after the process is finished, the substrate adsorption is more stable and the effect (1) can be further enhanced.

  (3) In the present invention as set forth in claim 3, in the plasma processing method in which the substrate is housed in a vacuum chamber and the substrate is plasma-treated in a state of being adsorbed on an electrostatic adsorption stage by electrostatic force, A first plasma discharge for charging is performed for a predetermined time, and after the first plasma discharge is once terminated, a second plasma discharge for plasma processing is performed after the predetermined time has elapsed to generate plasma on the surface of the substrate. Because the processing is performed, the adsorption force of the substrate due to electrostatic force increases immediately, and even in a short etching process, the contact is improved and uniform etching can be performed, and the etching residue within the substrate surface, etc. Will not occur.

  (4) In this invention of Claim 4, while adsorb | sucking the said board | substrate on the said electrostatic adsorption stage by electrostatic force, performing the said 1st plasma discharge, and after complete | finishing this 1st plasma discharge, Since the second plasma discharge is performed after a predetermined time to perform the plasma treatment on the substrate, the effect (3) can be further enhanced.

  The present invention provides a plasma processing apparatus having an electrostatic adsorption stage for adsorbing a substrate by electrostatic force, a first plasma discharge for charging the back surface of the substrate, and a first plasma for plasma processing the surface of the substrate. And a control means for generating plasma divided into two plasma discharges.

  That is, when the plasma is generated, a high frequency is temporarily discharged as a first plasma discharge for charging the back surface of the substrate, and then a high frequency is discharged for plasma treatment of the substrate surface. .

  As described above, according to the present embodiment, the substrate is attracted and held by the electrostatic force on the electrostatic adsorption stage composed of the lower electrode, and the first plasma discharge is performed in advance to The charge is charged, and the adsorptivity by the electrostatic force between the electrostatic adsorption stage and the substrate is greatly improved.

  By performing plasma etching by improving the contactability in such a stable substrate holding state and executing the second plasma discharge, uniform etching can be performed, and etching residue and the like are generated within the substrate surface. Can be prevented.

  In addition, since the above-described configuration only needs to add a control device capable of executing the control described above to a general plasma processing apparatus, it is easy to manufacture the plasma processing apparatus (plasma etching apparatus), and stable substrate holding is possible. A plasma processing apparatus having a function can be provided without significant cost increase.

  In this embodiment, the plasma processing apparatus includes a parallel plate type plasma in which a lower electrode and an upper electrode for generating plasma are provided in a vacuum chamber, and the lower electrode also serves as the electrostatic adsorption stage. The etching apparatus will be described. However, the present invention is not limited to such a configuration, and as a plasma processing apparatus, for example, a CVD apparatus, a sputtering apparatus, etc. are conceivable, and it does not necessarily have parallel plate electrodes such as an induction coil type. It doesn't matter.

  The control means adsorbs the substrate on the electrostatic adsorption stage by electrostatic force, executes the first plasma discharge, and after completing the first plasma discharge, waits for a predetermined time before the second plasma discharge. The plasma discharge is controlled to be executed.

  That is, after applying a DC voltage to the electrostatic adsorption stage to adsorb the substrate by electrostatic force, the first plasma discharge is performed, or a DC voltage is applied to the electrostatic adsorption stage and the first 1 plasma discharge is simultaneously performed. In any case, after the first plasma discharge is executed for a predetermined time, the second plasma discharge can be executed after a predetermined time.

  In this way, the first plasma discharge is not performed first, but a DC voltage is applied to at least the lower electrode to develop an electrostatic chuck function, and then the first plasma discharge is performed, thereby stabilizing the discharge. Substrate adsorption becomes possible, and the occurrence of etching defects and the like can be reliably prevented.

  It has been found that the electrostatic chuck function becomes stable with time, and after performing the first plasma discharge for a predetermined time, it is possible to perform plasma processing in a more stable state by leaving a predetermined time. It becomes.

  Although it is not preferable when a normal plasma etching apparatus is used, the first plasma discharge is first performed before the electrostatic chuck function is manifested to charge the substrate in advance, and the lower electrode is applied to the lower electrode. It is also conceivable that a powerful electrostatic chuck function is exhibited immediately when a DC voltage is applied.

  Plasma processing (plasma etching processing) using the plasma processing apparatus (plasma etching apparatus) is performed as follows.

  First, a substrate is accommodated in a chamber provided with an upper electrode and a lower electrode for generating plasma. Then, a DC voltage is applied to the lower electrode to attract and fix the substrate by an electrostatic chuck function, and a high frequency is discharged between the upper electrode and the lower electrode, and first plasma discharge is first performed for a predetermined time. The electric charge is charged on the back surface of the substrate. Then, after the first plasma discharge is once ended, a high frequency is discharged again between the upper electrode and the lower electrode after a predetermined time has elapsed, and a second plasma discharge is executed to perform a plasma etching process.

  By the way, for example, in the TFT manufacturing process, when the substrate is a quartz substrate, a conductive film may be formed on the back surface of the quartz substrate in advance. As a result, the charge on the back surface of the substrate is reliably charged, and a stable electrostatic attraction can be obtained.

  Hereinafter, embodiments of the present invention will be described more specifically with reference to the drawings. FIG. 1 is a schematic explanatory view of the plasma etching apparatus according to the present embodiment, and FIG. 2 is an explanatory view showing timings of plasma generation and electrostatic chuck function generation.

  In the present embodiment, the description will be made assuming that the plasma etching apparatus 1 is used in a manufacturing process of a TFT (Thin Film Transistor). The substrate 7 is a quartz substrate having a conductive film 70 formed on the back surface.

  As shown in FIG. 1, the plasma etching apparatus 1 according to the present embodiment includes a substantially cylindrical vacuum chamber 10, and a lower electrode that also serves as an electrostatic adsorption stage for placing a substrate on the bottom of the vacuum chamber 10. 2 and a parallel plate type in which an upper electrode 3 grounded is disposed on the upper portion of the chamber so as to face the lower electrode 2. Reference numeral 11 denotes a gas exhaust pipe, which is connected to a vacuum pump 13 through a control valve 12.

  The lower electrode 2 is connected to a high frequency power source 4 and a variable DC power source 5, and an upper layer portion is provided with an insulating material portion 20 whose upper surface is a substrate mounting surface, and a plurality of insulating material portions 20 are provided in the insulating material portion 20. The internal electrodes 21 and 22 are embedded, and the variable DC power source 6 is connected to the internal electrodes 21 and 22.

  And the electrostatic chuck mechanism is comprised by the internal electrodes 21 and 22 embedded in the said insulating material part 20, and the said variable DC power supply 6 connected to this, By applying a DC voltage to the internal electrodes 21 and 22, An electrostatic force is generated between the placed substrate 7 and the insulating material portion 20, and the substrate 7 is attracted by using this. In the present embodiment, a bipolar electrostatic chuck mechanism is employed in which a voltage having positive and negative polarities is applied to each of adjacent electrodes of the plurality of internal electrodes 21 and 22 to attract the substrate 7. Yes.

  The lower electrode 2 incorporates a heater (not shown) so that the adsorbing substrate 7 can be heated to a predetermined temperature according to the plasma processing.

On the other hand, the upper electrode 3 is grounded and provided with a plurality of jetting ports (not shown) so that an etching gas such as CF ₄ can be supplied into the vacuum chamber 10. 8 is a ground wire, and 9 is a gas supply pipe.

  In the above configuration, the plasma etching apparatus 1 is characterized by a first plasma discharge for charging the back surface of the substrate 7 and a second plasma discharge for plasma etching the surface of the substrate 7. There is a control means (not shown) for generating plasma by dividing. This control means controls the overall operation of the above-described configuration, and in particular controls the application timing and voltage by the high-frequency power source 4 and the variable DC power sources 5 and 6 as follows.

  That is, the substrate 7 is carried into the vacuum chamber 10 through a substrate transfer means (not shown) and placed on the lower electrode 2 serving as a stage. Then, the vacuum pump 13 is driven to evacuate the vacuum chamber 10, and an etching gas is introduced. At this time, the pressure in the vacuum chamber 10 is maintained at a predetermined pressure.

  Next, as shown in FIG. 2, a DC voltage is applied to the internal electrodes 21 and 22 embedded in the lower electrode 2 to develop an electrostatic chuck function, and the substrate 7 is attracted by electrostatic force. At the same time as the DC voltage is applied to the internal electrodes 21 and 22, high-frequency power is applied to the lower electrode 2 to execute the first plasma discharge, and positive and negative are applied to the conductive film 70 formed in advance on the back surface of the substrate 7. Charge the charge. The application timing of the high frequency power to the lower electrode 2 may be immediately after the application of the DC voltage to the internal electrodes 21 and 22.

In the present embodiment, the first plasma discharge time T ₁ is set to 1 second. In the present embodiment, the applied voltage V for the electrostatic chuck is set to V ₁ = 750 V in the initial state and V ₂ = 700 V in the subsequent execution of the second plasma discharge. It may be a constant value (see FIG. 3).

  Then, after 10 seconds have elapsed from the end of the first plasma discharge, high frequency power is applied to the lower electrode 2 again to execute a second plasma discharge, and the surface of the substrate 7 is etched.

The time T ₁ for the first plasma discharge is not particularly limited, but it has been experimentally confirmed that about 1 second is sufficient to charge the substrate 7 with electric charges. Further, the interval Int. Provided between the first plasma discharge and the second plasma discharge is for the purpose of stably exhibiting the electrostatic chuck function, and it is preferable that about 5 to 20 seconds is preferable. However, in the present embodiment, 10 seconds is set from the reliable electrostatic chuck function and the processing efficiency. By providing this interval Int., The etching process is performed in a state where the substrate 7 is more securely held, and it is possible to prevent an etching failure caused by the unstable holding of the substrate 7. The etching time T ₂ was 25 seconds.

  After the etching process is finished, the application of the high frequency power is stopped and the etching gas is exhausted to the outside of the vacuum chamber 10, and a voltage opposite to the DC voltage applied to the lower electrode 2 for the electrostatic chuck of the substrate 7 is applied. Then, the etched substrate 7 is taken out.

  As described above, in the present embodiment, the first plasma discharge is used to charge the back surface of the substrate 7 in advance, so that when a DC voltage is applied to the lower electrode 2, a powerful electrostatic chuck function can be obtained immediately. Even if the etching process is such that the second plasma discharge can be completed in a short time, the substrate 7 can be stably adsorbed and held, and the occurrence of defective etching can be prevented.

  By the way, as described above, in the present embodiment, after the first plasma discharge is finished, a DC voltage is applied to the lower electrode 2 for electrostatic chucking. However, as shown in FIG. A DC voltage may be applied to the lower electrode 2 while the plasma discharge is being performed. In the example shown in FIG. 3, the applied voltage for the electrostatic chuck is constant at V = 750V.

  As described above, the substrate 7 having the conductive film 70 formed on the back surface is accommodated in the vacuum chamber 10 provided with the lower electrode 2 and the upper electrode 2 for generating plasma. When performing plasma processing while being adsorbed by electrostatic force, a first plasma discharge for charging the back surface (conductive film 70) of the substrate 7 was performed for a predetermined time, and the first plasma discharge was temporarily terminated. After that, since the second plasma discharge for performing plasma etching is performed after a predetermined time has elapsed, the adhesion force due to electrostatic force is increased between the substrate 7 and the lower electrode 2, even if the conductive film 70 is formed. Even if the film thickness varies or the thickness is insufficient, the contact between the substrate 7 and the lower electrode 2 is improved, and uniform etching can be performed and etching can be performed within the substrate surface. Such is not generated grayed remaining. In addition, since the electrostatic chuck function is sufficiently exhibited before the etching process is started, the above-described effect can be obtained even in a short etching process.

  INDUSTRIAL APPLICABILITY The present invention has a configuration in which a substrate is adsorbed and held by an electrostatic force on an electrostatic adsorption stage, such as a plasma etching apparatus, a CVD apparatus, or a sputtering apparatus, and is suitably used for an apparatus that performs plasma processing using a plasma source. be able to.

It is typical explanatory drawing of the plasma etching apparatus which concerns on this Embodiment. It is explanatory drawing which shows an example of the timing of plasma generation and electrostatic chuck function generation. It is explanatory drawing which shows an example of the timing of plasma generation and electrostatic chuck function generation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma etching apparatus 2 Lower electrode 3 Upper electrode 7 Substrate 10 Vacuum chamber 21, 22 Internal electrode

Claims (4)

In a plasma processing apparatus equipped with an electrostatic adsorption stage that adsorbs a substrate by electrostatic force,
Control means for generating plasma by dividing into a first plasma discharge for charging the back surface of the substrate and a second plasma discharge for plasma processing the surface of the substrate. Plasma processing equipment.   The control means adsorbs the substrate on the electrostatic adsorption stage by electrostatic force, executes the first plasma discharge, and after completing the first plasma discharge, waits for a predetermined time before the second plasma discharge. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is controlled to perform plasma discharge. In a plasma processing method of storing a substrate in a vacuum chamber and performing plasma processing in a state where this substrate is adsorbed on an electrostatic adsorption stage by electrostatic force,
A first plasma discharge for charging the back surface of the substrate is performed for a predetermined time, and after the first plasma discharge is temporarily terminated, a second plasma discharge for plasma processing is performed after a predetermined time has elapsed. A plasma processing method comprising performing plasma processing on a surface of a substrate. The substrate is adsorbed by an electrostatic force on an electrostatic adsorption stage disposed in the vacuum chamber, and the first plasma discharge is performed. After the first plasma discharge is finished, a predetermined time is passed. The plasma processing method according to claim 3, wherein the substrate is subjected to plasma processing by executing a second plasma discharge.

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