JP2016195145A - Plasma processing apparatus and plasma processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide plasma processing apparatus and method that can enhance the yield of products when a substrate held on a transfer carrier is subjected to plasma processing.SOLUTION: In a plasma processing apparatus for performing plasma processing on a substrate held on a transfer carrier, the transfer carrier includes a holding sheet and a frame arranged at the outer peripheral portion of the holding sheet, and the substrate is held on a holding sheet. The plasma processing apparatus includes a reaction chamber, a stage which is disposed inside the reaction chamber and mounts the transfer carrier, an electrostatic adsorption mechanism having an electrode portion provided inside the stage, a support portion for supporting the transfer carrier between a mount position on the stage and a delivery position spaced upward from the stage, and an elevating mechanism for moving the support portion upwards and downwards relatively to stage. When the support portion is moved downwards to mount the transfer carrier on the stage, the electrostatic adsorption mechanism starts to apply a voltage to the electrode portion before the outer peripheral portion of the holding sheet comes into contact with the stage.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a plasma processing apparatus and a plasma processing method, and more particularly to a plasma processing apparatus and a plasma processing method for processing a substrate held on a carrier.

  As a method for dicing a substrate, plasma dicing is known in which a substrate on which a resist mask is formed is subjected to plasma etching and divided into individual chips. Patent Document 1 discloses a plasma processing stage (hereinafter simply referred to as a stage) in a state where a substrate is attached to a transport carrier including a frame and a holding sheet that covers an opening of the frame in order to improve handling of the substrate in transport or the like. ) And plasma processing is taught.

JP 2009-94436 A

  When the substrate is mounted on the stage with the carrier held on the stage and plasma processing is performed, the carrier is usually attracted to the stage by an electrostatic chucking mechanism called an electrostatic chuck. The electrostatic adsorption mechanism applies a voltage to an electrostatic chuck electrode (hereinafter referred to as an ESC electrode) disposed inside the stage, and Coulomb force or Johnson acting between the ESC electrode and the transport carrier. -The carrier is attracted to the stage by the Rahbek force. The stage is cooled. By performing the plasma processing while the transport carrier is adsorbed on the cooled stage, the transport carrier during the plasma processing can be effectively cooled.

  In recent years, electronic devices have become smaller and thinner, and the thickness of IC chips and the like mounted on electronic devices has been reduced. Along with this, the thickness of the substrate for forming an IC chip or the like to be diced is also reduced, and the substrate is easily bent.

  In addition, the holding sheet for holding the substrate is also small in thickness and easily bent. Therefore, the carrier carrying the substrate may be placed on the stage with the holding sheet wrinkled. Even if the transport carrier is attracted to the stage by the electrostatic attraction mechanism, the wrinkles are not eliminated. If the plasma processing is performed with wrinkles remaining on the holding sheet, abnormal discharge occurs in the wrinkled portions or the temperature of the wrinkled portions increases, making it difficult to perform the plasma processing normally.

  One aspect of the present invention relates to a plasma processing apparatus for performing plasma processing on a substrate held on a transport carrier. The transport carrier includes a holding sheet and a frame disposed on the outer periphery of the holding sheet, and the substrate is held by the holding sheet. The plasma processing apparatus includes a reaction chamber, a stage disposed inside the reaction chamber, on which a transport carrier is mounted, an electrostatic adsorption mechanism including an electrode provided inside the stage, and a transport carrier on the stage. A support unit that supports between the mounting position and a delivery position that is spaced upward from the stage; and an elevating mechanism that raises and lowers the support unit relative to the stage. In the case of mounting, before the outer peripheral portion of the holding sheet contacts the stage, the electrostatic adsorption mechanism starts applying a voltage to the electrode portion.

  Another aspect of the present invention relates to a plasma processing method for performing plasma processing on a substrate by mounting a carrier on which the substrate is held on a stage provided in the plasma processing apparatus. The transport carrier includes a holding sheet and a frame disposed on the outer periphery of the holding sheet, and the substrate is held by the holding sheet. In the plasma processing method, the transport carrier is supported at a transfer position away from the stage at a support portion that can be raised and lowered with respect to the stage, and the support portion is lowered to place the transport carrier at the mounting position on the stage. And a step of applying a voltage to the electrode part of the electrostatic adsorption mechanism provided inside the stage, and applying the voltage to the electrode part before the outer peripheral part of the holding sheet contacts the stage. To start.

  According to the present invention, the yield of products is improved when plasma processing is performed on a substrate held on a transport carrier.

It is the top view (a) which shows roughly the conveyance carrier holding the board | substrate which concerns on one Embodiment of this invention, and sectional drawing (b) in the BB line. It is a conceptual diagram of the plasma processing apparatus which concerns on one Embodiment of this invention. It is a conceptual diagram which shows the relationship between the ESC electrode which concerns on one Embodiment of this invention, and DC power supply. It is a conceptual graph which took the time after the support part which concerns on one Embodiment of this invention started a fall, and took the voltage applied to an ESC electrode on the vertical axis | shaft. It is explanatory drawing which shows the bending of the holding sheet which concerns on one Embodiment of this invention. It is a conceptual diagram which shows a mode after the support part which concerns on one Embodiment of this invention begins to fall until a conveyance carrier is mounted in a stage ((a)-(d)). It is a conceptual diagram which shows a part of operation | movement of the plasma processing apparatus which concerns on one Embodiment of this invention ((a)-(e)). FIG. 4 is a conceptual graph ((a) and (b)) in which the horizontal axis represents the time after power is applied to the antenna from the first high-frequency power supply according to an embodiment of the present invention, and the vertical axis represents the voltage applied to the ESC electrode. ) And a conceptual graph (c) in which the horizontal axis is taken in the same manner and the electric power input to the antenna is taken in the vertical axis. It is a conceptual graph which took the time after the support part which concerns on other one Embodiment of this invention started a fall, and took the voltage applied to an ESC electrode on the vertical axis | shaft. It is a notional graph which took the time after the support part concerning other 1 embodiment of the present invention started descent, and took the voltage applied to an ESC electrode on the vertical axis.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments of the present invention.
FIG. 1A is a top view schematically showing a transport carrier 10 according to an embodiment of the present invention, and FIG. 1B shows the transport carrier 10 in an unloaded state in FIG. It is sectional drawing in the BB line. Although FIG. 1 illustrates the case where the frame 2 and the substrate 1 are both circular, the present invention is not limited to this.

  As shown in FIG. 1A, the transport carrier 10 includes a substrate 1, a frame 2, and a holding sheet 3. The holding sheet 3 has an outer peripheral portion 3 c fixed to the frame 2. The substrate 1 is attached to the holding sheet 3 and held on the transport carrier. The outer peripheral portion 3 c is an overlapping portion of the holding sheet 3 with the frame 2. 1 (a) and 1 (b), the outer peripheral portion 3c is hatched for convenience.

  The substrate 1 is a processing target for plasma processing such as plasma dicing. The substrate 1 is formed by forming a circuit layer such as a semiconductor circuit, an electronic component element, or a MEMS on one surface of a substrate body (for example, Si, GaAs, SiC), and then the substrate body on the opposite side of the circuit layer. It is produced by grinding the back surface of the part and reducing the thickness. The thickness of the substrate 1 is usually very thin, about 25 to 150 μm. Therefore, the substrate 1 itself has almost no self-supporting property (rigidity). When the thickness of the substrate 1 is reduced, warping or bending may occur due to a difference in internal stress between the circuit layer portion and the substrate body portion. When warping or bending occurs, it becomes difficult to transport or cool the substrate 1 when performing plasma processing.

  Therefore, the outer peripheral portion 3 c of the holding sheet 3 is fixed to the substantially flat frame 2 in a state where tension is applied, and the substrate 1 is attached to the holding sheet 3. The holding sheet 3 is made of a resin having a thickness of about 50 to 150 μm, and has rigidity enough to hold the substrate 1. Moreover, the adhesion layer is formed in one surface of the holding sheet 3, and the board | substrate 1 is affixed on this adhesion layer. Thereby, the conveyance carrier 10 can hold the substrate 1, the holding sheet 3, and the frame 2 on substantially the same plane. Therefore, when plasma processing is performed on the substrate 1, handling such as transport of the substrate 1 and cooling during the plasma processing becomes easy.

  However, when the substrate 1 is attached to the holding sheet 3 whose outer peripheral portion 3c is fixed to the frame 2, the holding sheet 3 may be bent (see FIG. 1B). In FIG. 1B, the bending is emphasized for easy understanding.

The following four cases can be considered as causes of the holding sheet 3 to bend.
The first case is a case where the holding sheet 3 is bent due to distortion of the frame 2. The frame 2 is originally designed to be flat, but the flatness may be low due to variations and tolerances in manufacturing the frame 2 or repeated use in the production process. When the frame 2 having low flatness is used, the holding sheet 3 fixed to the frame 2 is bent.

  The second case is a case where the holding sheet 3 is bent due to the shape of the substrate 1. The transport carrier 10 holds the substrate 1 substantially flat by the tension of the holding sheet 3. For example, when the substrate 1 has a notch such as an orientation flat (orientation flat), the tension of the holding sheet 3 is uniform to the substrate 1. Don't join. In this case, wrinkles are generated in the holding sheet 3 in the vicinity of the orientation flat, and this is the bending of the holding sheet 3.

  The third case is a case where the holding sheet 3 is bent due to gravity. The carrier 10 holds the substrate 1 substantially flat by the tension of the holding sheet 3, but the holding sheet 3 is stretched due to the weight of the substrate 1 and the holding sheet 3, and the frame 2 is distorted and held. The sheet 3 is bent.

  The fourth case is a case where the holding sheet 3 is bent due to the stress of the substrate 1. A stress that warps the substrate 1 is applied to the substrate 1. On the other hand, the holding sheet 3 resists this stress by the adhesive force to which the substrate 1 is attached and the tension of the holding sheet 3, and suppresses the warp of the substrate 1 to keep the substrate 1 flat. At this time, if the stress of the substrate 1 is larger, the holding sheet 3 cannot suppress the warp of the substrate 1, the holding sheet 3 is stretched, and the holding sheet 3 is bent.

  Electrostatic adsorption electrodes (ESC electrodes) are roughly classified into two types, a monopolar type and a bipolar type. By applying a voltage to the ESC electrode, an attracting force is generated between the ESC electrode and the holding sheet 3, and the transport carrier 10 can be attracted to the stage 111.

  A monopolar ESC electrode is composed of at least one electrode, and a voltage having the same polarity is applied to all the electrodes. An electrostatic adsorption mechanism including a monopolar ESC electrode utilizes Coulomb force as an adsorption mechanism. By applying a voltage to the ESC electrode, a charge due to dielectric polarization is induced on the surface of the stage 111 made of a dielectric, and the transport carrier 10 placed on the stage 111 is charged. As a result, a Coulomb force acts between the charge induced on the surface of the stage 111 and the charged transport carrier 10, and the transport carrier 10 is attracted to the stage 111. In order to charge the carrier 10, plasma may be generated in the reaction chamber 103 and the carrier 10 may be exposed to the generated plasma.

  On the other hand, a bipolar ESC electrode includes a positive electrode and a negative electrode, and voltages having different polarities are applied to the positive electrode and the negative electrode, respectively. For example, a comb-shaped electrode 20 as shown in FIG. 3 is used as the bipolar ESC electrode. As shown in FIG. 3, a voltage V1 is applied to the positive electrode, and a voltage -V1 is applied to the negative electrode.

  As an adsorption mechanism of an electrostatic adsorption mechanism including a bipolar ESC electrode, there are a case where a Coulomb force is used and a case where a Johnson Rabeck force is used. Depending on the adsorption mechanism, the structure of the electrode and the material constituting the electrode (for example, ceramics) are appropriately selected. In any of the adsorption mechanisms, an adsorption force is generated between the ESC electrode and the conveyance carrier 10 by applying voltages having different polarities to the positive electrode and the negative electrode, and the conveyance carrier 10 can be adsorbed to the stage 111. . In the case of the bipolar type, unlike the case of the monopolar type, it is not necessary to charge the carrier 10 for adsorption.

  The bipolar electrode can be made to function as a monopolar type by applying a voltage to the positive electrode and the negative electrode. Specifically, it can be used as a monopolar ESC electrode by applying a voltage of the same polarity to the positive electrode and the negative electrode. Hereinafter, a case where voltages having different polarities are applied to the positive electrode and the negative electrode of the bipolar electrode is referred to as a bipolar mode, and a case where a voltage having the same polarity is applied to the positive electrode and the negative electrode is referred to as a unipolar mode.

  In the unipolar mode, a voltage having the same polarity is applied to the positive electrode and the negative electrode, and Coulomb force is used as an adsorption mechanism. Unlike the case of the bipolar mode, the carrier carrier cannot be adsorbed only by applying a voltage to the positive electrode and the negative electrode. In the unipolar mode, in order to attract the transport carrier 10, the transport carrier 10 needs to be charged. Therefore, when adsorbing in the monopolar mode, plasma is generated in the reaction chamber 103 and the carrier 10 is charged by exposing the carrier 10 to this plasma. As a result, the transport carrier 10 is attracted to the stage 111. As described above, the monopolar and bipolar ESC electrodes have been described. However, the transport carrier 10 can be adsorbed to the stage by using any type.

  As described above, when the carrier 10 having the holding sheet 3 bent is mounted on the stage, the holding sheet 3 or the substrate 1 itself may be wrinkled. Such wrinkles may occur in a region not in contact with the substrate 1 of the holding sheet 3 or may occur in a region in contact with the substrate 1 of the holding sheet 3. In the latter case, wrinkles may occur on the substrate 1 itself that is adhered to the holding sheet 3.

  Further, normally, the stage is cooled to, for example, 15 ° C. or less in order to prevent the transport carrier 10 from being heated by plasma irradiation and receiving thermal damage. By cooling the stage, the transport carrier 10 mounted on the stage is also cooled, and thermal damage to the transport carrier 10 is suppressed. However, when the holding sheet 3 comes into contact with the cooled stage, the holding sheet 3 may shrink. Since the outer peripheral portion 3 c of the holding sheet 3 is fixed to the frame 2, the shrinkage of the holding sheet 3 can be one of the causes of wrinkling of the holding sheet 3.

  When the wrinkled conveyance carrier is attracted to the stage by the electrostatic adsorption mechanism, at least a part of the wrinkle generated on the holding sheet 3 cannot come into contact with the stage, and a part of the holding sheet is lifted from the stage. Adsorbed in a state. When such a raised portion occurs in a region of the holding sheet 3 that is in contact with the substrate 1, if the plasma treatment is performed as it is, etching becomes uneven at the raised portion and other portions, and the processed shape is reduced. Variations and unprocessed parts occur. Furthermore, regardless of the region where the raised portion of the holding sheet 3 is generated, a local temperature rise or abnormal discharge may occur in the raised portion. There is a concern that the substrate 1, the holding sheet 3, and further the ESC electrode may be damaged by this temperature rise or abnormal discharge. Further, in the pick-up process after the plasma treatment, since the holding sheet 3 is wrinkled, it is difficult to accurately recognize the chip, and a pick-up mistake may occur. Further, in the subsequent appearance inspection process, there may be a case where the good product and the defective product are not accurately discriminated.

  In the present invention, before the transport carrier 10 is mounted on the stage, application of a voltage to the ESC electrode is started so that the holding sheet 3 is attracted to the stage without wrinkles.

(Plasma processing equipment)
First, a plasma processing apparatus 100 according to an embodiment of the present invention will be described with reference to FIG.
FIG. 2 schematically shows a cross section of a plasma processing apparatus 100 according to an embodiment of the present invention.

  The plasma processing apparatus 100 includes a stage 111. The carrier 10 is mounted on the stage 111 so that the surface (adhesive surface 3a) that holds the substrate 1 of the holding sheet 3 faces upward. Above the stage 111, a cover 124 having a window 124W for covering at least a part of the frame 2 and the holding sheet 3 and exposing at least a part of the substrate 1 is disposed.

  The stage 111 and the cover 124 are disposed in the reaction chamber (vacuum chamber) 103. The top of the vacuum chamber 103 is closed by a dielectric member 108, and an antenna 109 as an upper electrode is disposed above the dielectric member 108. The antenna 109 is electrically connected to the first high frequency power supply 110A. The stage 111 is disposed on the bottom side in the vacuum chamber 103.

  A gas inlet 103 a is connected to the vacuum chamber 103. A process gas source 112 and an ashing gas source 113, which are supply sources of plasma generating gas, are connected to the gas inlet 103a by pipes. The vacuum chamber 103 is provided with an exhaust port 103b, and a pressure reducing mechanism 114 including a vacuum pump for exhausting and depressurizing the gas in the vacuum chamber 103 is connected to the exhaust port 103b.

  The stage 111 includes a substantially circular electrode layer 115, a metal layer 116, a base 117 that supports the electrode layer 115 and the metal layer 116, and an outer peripheral portion 118 that surrounds the electrode layer 115, the metal layer 116, and the base 117. Is provided. Inside the electrode layer 115, an electrode part (hereinafter referred to as an ESC electrode) 119 constituting an electrostatic attraction mechanism and a high-frequency electrode part 120 electrically connected to the second high-frequency power source 110B are arranged. . A DC power supply 126 is electrically connected to the ESC electrode 119. The electrostatic adsorption mechanism is composed of an ESC electrode 119 and a DC power supply 126.

  The metal layer 116 is made of, for example, aluminum having an alumite coating on the surface. A coolant channel 127 is formed in the metal layer 116. The refrigerant flow path 127 cools the stage 111. By cooling the stage 111, the transport carrier 10 mounted on the stage 111 is cooled, and the cover 124 that partially contacts the stage 111 is also cooled. The refrigerant in the refrigerant flow path 127 is circulated by the refrigerant circulation device 125.

  In the vicinity of the outer periphery of the stage 111, a plurality of support portions 122 that penetrate the stage 111 are arranged. The support part 122 is driven up and down by an up-and-down mechanism 123A. When the support unit 122 is at the transfer position above the stage 111, the transfer carrier 10 is transferred into the vacuum chamber 103 by the transfer mechanism (not shown) and transferred to the support unit 122. At this time, the support unit 122 supports the frame 2 of the transport carrier 10. More preferably, the support part 122 supports the overlapping part (the outer peripheral part 3 c of the holding sheet 3) of the transport carrier 10 between the frame 2 and the holding sheet 3. The transport carrier 10 is mounted at a predetermined position of the stage 111 by lowering the upper end surface of the support unit 122 to the same level or lower as the stage 111.

  A plurality of lifting rods 121 are connected to the end of the cover 124 so that the cover 124 can be lifted and lowered. The elevating rod 121 is driven up and down by the elevating mechanism 123B. The raising / lowering operation of the cover 124 by the raising / lowering mechanism 123B can be performed independently of the raising / lowering mechanism 123A.

  The control device 128 includes a first high-frequency power source 110A, a second high-frequency power source 110B, a process gas source 112, an ashing gas source 113, a decompression mechanism 114, a refrigerant circulation device 125, an elevating mechanism 123A, an elevating mechanism 123B, and an electrostatic adsorption mechanism. The operation of the elements constituting the plasma processing apparatus 100 is controlled.

(flame)
The frame 2 is a frame having an opening having an area equal to or larger than that of the entire substrate 1 and has a predetermined width and a substantially constant thin thickness. The frame 2 is rigid enough to hold and transport the holding sheet 3 and the substrate 1.

  The shape of the opening of the frame 2 is not particularly limited, but may be, for example, a circle, a rectangle, or a polygon such as a hexagon. The frame 2 may be provided with notches 2a and corner cuts 2b for positioning. Examples of the material of the frame 2 include metals such as aluminum and stainless steel, and resins. One surface 3 a of the outer peripheral portion 3 c of the holding sheet 3 is attached to one surface of the frame 2.

(Holding sheet)
The holding sheet 3 includes, for example, a surface having an adhesive (adhesive surface 3a) and a surface not having an adhesive (non-adhesive surface 3b). The adhesive surface 3 a side of the outer peripheral portion 3 c is attached to one surface of the frame 2. In addition, the substrate 1 is attached to a portion exposed from the opening of the frame 2 of the adhesive surface 3a. The pressure-sensitive adhesive surface 3a is preferably made of a pressure-sensitive adhesive component whose adhesive force decreases when irradiated with ultraviolet rays. This is because, by performing ultraviolet irradiation after dicing, the separated substrate (chip) is easily peeled off from the adhesive surface 3a and is easily picked up. For example, the holding sheet 3 may be composed of a UV curable acrylic pressure-sensitive adhesive (adhesive surface 3a) and a polyolefin base material (non-adhesive surface 3b). In this case, the thickness of the UV curable acrylic pressure-sensitive adhesive is preferably 5 to 20 μm, and the thickness of the polyolefin substrate is preferably 50 to 150 μm.

  The holding sheet 3 may have conductivity. In the case of a unipolar ESC electrode or an ESC electrode that operates in a unipolar mode, a high adsorption force can be obtained for the stage 111 regardless of whether the holding sheet 3 is conductive. On the other hand, in the case of the ESC electrode operating in the bipolar mode, if the holding sheet 3 has poor conductivity, the attractive force to the stage 111 becomes weak. Therefore, the holding sheet 3 having conductivity is particularly useful when the bipolar ESC electrode is operated in the bipolar mode. As a result, when the bipolar ESC electrode is operated in the bipolar mode, it is possible to increase the suction force with respect to the stage 111.

(substrate)
The substrate 1 is an object of plasma processing and is not particularly limited. The material of the substrate 1 is not particularly limited. For example, a semiconductor, a dielectric, a metal, or a laminate of these may be used. Examples of the semiconductor include silicon (Si), gallium arsenide (GaAs), gallium nitride (GaN), and silicon carbide (SiC). Examples of the dielectric include silicon dioxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), polyimide, lithium tantalate (LiTaO ₃ ), lithium niobate (LiNbO ₃ ), and the like. The size is not particularly limited, and for example, the maximum diameter is about 50 mm to 300 mm and the thickness is about 25 to 150 μm. Further, the shape of the substrate 1 is not particularly limited, and is, for example, circular or square. The substrate 1 may be provided with notches (not shown) such as an orientation flat (orientation flat) and a notch.

  Further, a resist mask is formed in a desired shape on the surface of the substrate 1 that is not attached to the holding sheet 3 (not shown). The portion where the resist mask is formed is protected from etching by plasma. The portion where the resist mask is not formed can be etched by plasma from the front surface to the back surface.

(Electrostatic adsorption mechanism)
The electrostatic attraction mechanism applies a voltage from the DC power supply 126 to the ESC type electrode 119 disposed inside the stage 111 (electrode layer 115), and Coulomb force acting between the stage 111 and the transport carrier 10 or Johnson Rabeck. The conveyance carrier 10 is attracted to the stage 111 by force. The ESC electrode 119 is arranged so that the center thereof and the center of the stage 111 substantially coincide. Note that the center of the ESC electrode 119 can be regarded as the center of the perfect circle when a minimum perfect circle in which the entire ESC electrode 119 fits is drawn.

  The ESC electrode 119 may be a bipolar type or a monopolar type. Further, the bipolar ESC electrode 119 may be operated in a bipolar mode or a monopolar mode. When the ESC electrode 119 operates in a single-pole type or a single-pole mode, the DC carrier 126 and the first high-frequency power source 110A are activated, so that the transport carrier 10 is attracted to the stage 111. Specifically, the first high-frequency power source 110A is operated to generate plasma in the reaction chamber 103 to charge the surface of the transport carrier 10, and the DC power source 126 is operated to operate in a monopolar type or a monopolar mode. By applying a voltage to the ESC type electrode 119, an attractive force is generated between the transport carrier 10 and the stage 111.

  When the ESC electrode 119 is a bipolar type and operates in the bipolar mode, the transport carrier 10 is attracted to the stage 111 by operating the DC power supply 126. Specifically, the DC power supply 126 is operated to apply voltages having different polarities to the positive electrode and the negative electrode of the ESC type electrode 119, so that an adsorption force is generated between the transport carrier 10 and the stage 111. Hereinafter, the present embodiment will be described by taking a case where the ESC electrode 119 is a bipolar type as an example, but the present invention is not limited to this.

  FIG. 3 conceptually shows the relationship between the bipolar ESC electrode 119 and the DC power supply 126. The ESC electrode 119 is, for example, a comb electrode as shown in FIG. In FIG. 3, a voltage of V1 is applied to the positive electrode, and a voltage of -V1 is applied to the negative electrode. The shape of the ESC electrode 119 is not limited to this, and may be selected as appropriate.

  The control device 128 controls the application of voltage to the ESC electrode 119 according to the operation of the support part 122. That is, when the transport carrier 10 is mounted on the stage 111, the electrostatic adsorption mechanism starts applying a voltage to the ESC electrode 119 before the outer peripheral portion 3 c of the holding sheet 3 contacts the stage 111.

  The timing for starting the voltage application to the ESC electrode 119 is not particularly limited as long as it is before the outer peripheral portion 3 c of the holding sheet 3 contacts the stage 111. For example, the voltage application may be started before the holding sheet 3 contacts the stage 111, that is, before the bent portion of the holding sheet 3 (hereinafter sometimes referred to as a bent portion) contacts the stage 111. The voltage application may be started after the bent portion of the holding sheet 3 is in contact with the stage 111 and before the outer peripheral portion 3 c is in contact with the stage 111.

  Hereinafter, this embodiment will be described in detail. In addition, this invention is not limited to this embodiment, A various change is possible.

(First embodiment)
In the present embodiment, voltage application is started before the bent portion of the holding sheet 3 contacts the stage 111. FIG. 4 shows a conceptual graph in which the horizontal axis represents the time since the support unit 122 started to descend, and the vertical axis represents the voltage applied to the ESC electrode 119. In FIG. 4, the descent start is when the support unit 122 that supports the transport carrier 10 starts to descend. The landing start is the time when the bent portion of the holding sheet 3 held by the carrier 10 starts to contact the stage 111. Completion of landing is when the upper end surface of the support part 122 has been lowered to the same level or lower as the stage 111 and the outer peripheral part 3 c (at least a part of the holding sheet 3) has contacted the stage 111.

  Whether or not the bent portion of the holding sheet 3 is in contact with the stage 111 is determined, for example, by the distance D at which the upper end surface of the support portion 122 is lowered. The deflection Tc (see below) of the holding sheet 3 held on the transport carrier 10 is measured in advance, and the support portion 122 has a distance T between the upper end surface of the support portion 122 and the stage 111 of Tc. Know the descent distance D. The time point when the descending distance of the support part 122 becomes D is regarded as the time point when the bent part of the holding sheet 3 held by the transport carrier 10 starts to contact the stage 111.

  The deflection Tc is obtained as follows, for example. As shown in FIG. 5, the transport carrier 10 is placed on the upper end surface 122 a of the support part 122 that is raised to the extent that the holding sheet 3 does not contact the stage 111. At this time, in the cross section passing through the center of the transport carrier 10, the shortest distance between the straight line L1 passing through the surface 3b of the outer peripheral portion 3c and the tangent L2 of the surface 3b in the portion where the holding sheet 3 is most bent (flexible portion), Let it be a deflection Tc.

  The deflection Tc is not necessarily measured in the reaction chamber 103 or the plasma processing apparatus 100. For example, the measurement may be performed in advance by a non-contact type optical measuring device or the like before performing the processing in the plasma processing apparatus 100. In FIG. 5, the bending Tc is emphasized for easy understanding. When the diameter of the frame 2 is about 300 mm, the diameter of the substrate 1 is about 150 mm, the thickness of the substrate 1 is about 100 μm, and the thickness of the holding sheet is about 110 μm, the deflection Tc is about 50 μm to 800 μm, for example.

  FIG. 6 conceptually illustrates a state from when the support portion 122 supporting the transport carrier 10 starts to descend until the transport carrier 10 is mounted on the stage 111. For easy understanding, in FIG. 6, the ESC electrode 119 to which a voltage is applied is hatched. In FIG. 6 as well, for the sake of explanation, the deflection is emphasized.

  As shown in FIG. 6A, first, the support portion 122 that supports the transport carrier 10 starts to descend. At this time, the distance T between the upper end surface 122a of the support portion 122 and the stage is larger than the deflection Tc (T> Tc). After the lowering of the support part 122 is started, a voltage is applied to the ESC electrode 119. At the same time as the support portion 122 continues to descend and the bent portion of the holding sheet 3 comes into contact with the stage 111 (T = Tc), the contact portion is attracted to the stage 111 (FIG. 6B). Thereafter, the contact portion of the holding sheet 3 with the stage 111 is immediately attracted to the stage 111 (FIGS. 6C and 6D).

  The holding sheet 3 is sequentially attracted to the stage 111 from the most bent part. Therefore, it is difficult for wrinkles to occur. Further, the holding sheet 3 is adsorbed simultaneously with the contact with the stage 111. Therefore, even when the stage 111 is cooled, the holding sheet 3 is adsorbed without contracting. Therefore, the holding sheet 3 is attracted to the stage 111 without wrinkles. Therefore, the substrate 1 is uniformly etched by the subsequent plasma treatment, and the product yield is improved.

  Hereinafter, the operation of the plasma processing apparatus will be specifically described with reference to FIG. In FIG. 7, the bending is emphasized for easy understanding of the description.

  In the vacuum chamber 103, in order to support the conveyance carrier 10, it waits in the state where the some support part 122 raised. The cover 124 also stands by at the raised position (FIG. 7 (a)). The transport carrier 10 is transported into the vacuum chamber 103 by a transport mechanism (not shown) and transferred to the plurality of support parts 122 (FIG. 7B).

  The transport carrier 10 is placed on the upper end surface 122a of the support portion 122 so that the surface (adhesive surface 3a) that holds the substrate 1 of the holding sheet 3 faces upward. The frame 2 may be placed on the upper end surface 122 a of the support portion 122 via the outer peripheral portion 3 c of the holding sheet 3, or the frame 2 may be placed directly on the upper end surface 122 a of the support portion 122. . In particular, from the viewpoint of suppressing separation between the frame 2 and the holding sheet 3 during the lifting and lowering operation of the support part 122, the transport carrier 10 is placed on the support part 122 via the outer peripheral part 3 c of the holding sheet 3. It is preferable to be placed on the end face 122a.

  Next, the support part 122 descends (FIG. 7C). The DC power supply 126 applies a voltage to the ESC electrode 119 after the transport carrier 10 is transferred to the support unit 122 and before the bent portion of the holding sheet 3 contacts the stage 111 for the first time.

  When the ESC electrode 119 is monopolar, the transport carrier 10 is placed on the upper end surface 122a of the support 122 by the transport mechanism, and after the transport mechanism has left the vacuum chamber 103, a voltage is applied to the ESC electrode 119. In the meantime, low power (for example, 500 W or less) is supplied from the first high-frequency power supply 110A to the antenna 109, and plasma is generated in the reaction chamber 103. As a result, the surface of the transport carrier 10 is charged and a voltage is applied to the ESC electrode 119. At the same time, the transport carrier 10 can be attracted to the stage 111.

  Further, when the support portion 122 continues to descend, the outer peripheral portion 3c of the holding sheet 3 comes into contact with the stage 111, and the transport carrier 10 is mounted at a predetermined position on the stage 111 (FIG. 7D). When the upper end surface 122 a of the support part 122 is lowered to the same level or lower as the stage 111, it can be determined that the outer peripheral part 3 c of the holding sheet 3 is in contact with the stage 111.

  When the upper end surface 122a is lowered below the same level as the stage 111, the elevating rod 123 is driven by the elevating mechanism 123B, and the cover 124 is lowered to a predetermined position (FIG. 7 (e)). When the cover 124 is disposed at a predetermined lowered position, the portion of the frame 2 and the holding sheet 3 that does not hold the substrate 1 is covered with the cover 124 without contacting the cover 124, and the substrate 1 is covered with the window of the cover 124. The part 124W is exposed.

  The cover 124 is, for example, a donut shape having a substantially circular outer contour, and has a certain width and a small thickness. The inner diameter of the cover 124 (the diameter of the window portion 124 </ b> W) is smaller than the inner diameter of the frame 2, and the outer diameter of the cover 124 is larger than the outer diameter of the frame 2. Therefore, when the transport carrier 10 is mounted at a predetermined position on the stage and the cover 124 is lowered, the cover 124 can cover at least a part of the frame 2 and the holding sheet 3. At least a part of the substrate 1 is exposed from the window portion 124W. At this time, the cover 124 does not contact any of the frame 2, the holding sheet 3, and the substrate 1. The cover 124 is made of, for example, a dielectric such as ceramics (for example, alumina or aluminum nitride) or quartz, or a metal such as aluminum or aluminum whose surface is anodized.

  When the support part 122 and the cover 124 are disposed at predetermined positions, the process gas is introduced into the vacuum chamber 103 from the process gas source 112 through the gas inlet 103a. On the other hand, the decompression mechanism 114 exhausts the gas in the vacuum chamber 103 from the exhaust port 103b, and maintains the inside of the vacuum chamber 103 at a predetermined pressure.

  Subsequently, high-frequency power is supplied from the first high-frequency power source 110 </ b> A to the antenna 109 to generate plasma P in the vacuum chamber 103. The generated plasma P is composed of ions, electrons, radicals, and the like. Next, high-frequency power is supplied from the second high-frequency power source 110B to the high-frequency electrode 120, and plasma processing for the substrate 1 is started. The incident energy of ions on the substrate 1 can be controlled by a bias voltage applied to the high-frequency electrode 120 from the second high-frequency power source 110B. The portion from the front surface to the back surface of the portion exposed from the resist mask formed on the substrate 1 is removed by a physicochemical reaction with the generated plasma P, and the substrate 1 is singulated.

The conditions for the plasma treatment are set according to the material of the substrate 1 and the like. For example, when the substrate 1 is Si, the substrate 1 is etched by generating a plasma P of a fluorine-containing gas such as sulfur hexafluoride (SF ₆ ) in the vacuum chamber 103. In this case, for example, while the SF ₆ gas is supplied from the process gas source 112 at 100 to 800 sccm, the pressure in the reaction chamber 103 is controlled to 10 to 50 Pa by the decompression mechanism 114. The antenna 109 is supplied with a high frequency power of 1000 to 5000 W and a frequency of 13.56 MHz, and the high frequency electrode 120 is supplied with a high frequency power of 50 to 1000 W and a frequency of 13.56 MHz. At that time, the temperature of the refrigerant circulated in the stage 111 is set to −20 to 20 ° C. by the refrigerant circulation device 125 in order to suppress the temperature rise of the carrier 10 due to the plasma treatment. Thereby, the temperature of the carrier 10 during plasma processing can be suppressed to 100 ° C. or lower.

In the etching process, the surface of the substrate 1 exposed from the resist mask is desirably etched vertically. In this case, for example, an etching step using a fluorine-based gas plasma such as SF ₆ and a protective film deposition step using a fluorocarbon gas plasma such as perfluorocyclobutane (C ₄ F ₈ ) may be alternately repeated. .

  After the plasma P is generated, the operation mode of the ESC type electrode 119 may be switched from the bipolar mode to the monopolar mode. When the operation mode of the ESC electrode 119 is bipolar mode, the surface of the substrate 1 above the positive electrode of the ESC electrode 119 (positive surface) and the surface of the substrate 1 above the negative electrode of the ESC electrode 119 (negative electrode surface) ) And slightly different potentials. Further, since the Coulomb force is generated more strongly on the positive electrode side than on the negative electrode side, there is a slight difference in the adsorption force.

  Therefore, when the plasma processing is started in the bipolar mode, a difference in temperature of the substrate 1 due to a difference in adsorption force to the stage 111 occurs between the positive electrode side surface and the negative electrode side surface of the ESC type electrode 119. Further, there may be a difference in effective bias voltage applied to the substrate 1 between the positive electrode side surface and the negative electrode side surface. Furthermore, there may be a difference in the degree of etching between the positive electrode side surface and the negative electrode side surface. For these reasons, uniform plasma processing on the substrate 1 may be difficult.

  Switching from bipolar mode to unipolar mode is the same as the other voltage by, for example, inverting the polarity of the voltage applied to one of the positive electrode or the negative electrode or changing the voltage applied to one of the positive electrode or the negative electrode It is done by making it.

  At the time of switching from the bipolar mode to the monopolar mode, the suction force of the transport carrier 10 to the stage 111 may be momentarily weakened and cooling of the transport carrier 10 may be insufficient. Therefore, the switching from the bipolar mode to the monopolar mode is preferably performed while low power (for example, 500 W or less) is being applied to the antenna 109 from the first high frequency power supply 110A.

  In other words, first, the operation mode of the ESC type electrode 119 is switched from the bipolar mode to the monopolar mode while inputting low power from the first high frequency power supply 110A to the antenna 109 to generate low power plasma. After the switching is completed, it is preferable to perform plasma processing by supplying high power from the first high-frequency power source 110A to the antenna 109 (see FIG. 8C). When the input power to the antenna 109 is low, the energy of the generated plasma is weak, so that the heat transferred from the plasma to the carrier 10 is small. Therefore, there is little need to cool the transport carrier 10 by strongly adsorbing it to the stage 111. Therefore, at the time of switching from the bipolar mode to the monopolar mode, problems due to insufficient cooling of the transport carrier 10 are less likely to occur.

  The voltage applied to each ESC type electrode 119 may be increased after switching to the monopolar mode and before starting the plasma treatment. FIGS. 8A and 8B are conceptual diagrams in which the horizontal axis represents the time after power is applied to the antenna 109 from the first high frequency power supply 110A and the vertical axis represents the voltage applied to each ESC type electrode 119. A simple graph. As shown in FIGS. 8A and 8B, after switching to the unipolar mode, the voltage applied to each ESC type electrode 119 is increased stepwise to + V2 to attract the carrier 10 to the stage 111. To raise enough. Thereafter, high power is supplied from the first high-frequency power source 110A to the antenna 109, and plasma processing is started.

  Specifically, for example, the positive voltage (+ V1) in the bipolar mode is 1500 V, the negative voltage (−V1) is −1500 V, and the input power (low power) of the antenna 109 is 500 W. Next, the bipolar mode is switched to the monopolar mode by changing the negative voltage (-V1) from -1500V to 1500V. Thereafter, both the positive electrode voltage (+ V1) and the negative electrode voltage (−V1) are gradually increased to 3000 V (+ V2). Finally, the plasma processing is performed by increasing the input power (high power) to the antenna 109 to 2000 W to 5000 W. Thereby, while suppressing the occurrence of problems associated with switching from the bipolar mode to the unipolar mode, the carrier carrier 10 is strongly attracted to the stage 111 and the carrier carrier 10 is reliably cooled even during plasma processing. Can do.

  After singulation, ashing is executed. An ashing process gas (for example, oxygen gas or a mixed gas of oxygen gas and fluorine gas) is introduced into the vacuum chamber 103 from the ashing gas source 113. On the other hand, the vacuum mechanism 114 is evacuated to maintain the vacuum chamber 103 at a predetermined pressure. By applying high-frequency power from the first high-frequency power supply 110A, oxygen plasma is generated in the vacuum chamber 103, and the resist mask on the surface of the substrate 1 (chip) exposed from the window 124W of the cover 124 is completely removed. Is done.

  Finally, the carrier 10 holding the separated substrate 1 is unloaded from the plasma processing apparatus 100. The unloading of the substrate 1 may be performed by a procedure reverse to the procedure of mounting the substrate 1 shown in FIG. That is, after raising the cover 124 to a predetermined position, the applied voltage to the ESC type electrode 119 is set to zero, the suction of the transport carrier 10 to the stage 111 is released, and the support part 122 is raised. When the carrier at the time of plasma processing remains on the carrier carrier 10 and the carrier carrier 10 remains and adsorbs on the stage 111, the first high frequency power source 110A, for example, from the first high-frequency power source 110A, for example, before or during the raising of the support 122 A weak high frequency power of about 200 W may be input to generate a weak plasma, and the transport carrier 10 may be discharged.

  As a cause of the bending of the holding sheet 3, the first to fourth cases can be considered as described above. The present embodiment can be applied to any of these cases, but is particularly useful when the frame 2 is distorted. When the frame 2 is not distorted, the transport carrier 10 can be placed almost flat on the stage 111. However, when the frame 2 is distorted, the thin and light substrate 1 and the holding sheet 3 are lifted from the stage 111 due to the distortion of the frame 2, and a gap is generated between the stage 111 and the frame 2. In addition, the substrate 2 and the holding sheet 3 are wrinkled by the distortion of the frame 2.

  In the present embodiment, before the outer peripheral portion 3 c of the holding sheet 3 contacts the stage 111, application of a voltage is started to the ESC electrode 119, and the holding sheet 3 and the substrate 1 are attracted to the stage 111. That is, the holding sheet 3 and the substrate 1 are attracted to the stage 111 before the frame 2 is placed on the stage 111. Thereby, even if the frame 2 is distorted, the floating of the substrate 1 and the holding sheet 3 can be suppressed. Therefore, generation | occurrence | production of the clearance gap between the stages 111 and generation | occurrence | production of a wrinkle are suppressed.

(Second Embodiment)
This embodiment is the same as the first embodiment except that the voltage applied to the ESC electrode 119 is increased as the support portion is lowered. When the applied voltage is a negative voltage, the applied voltage is increased in the negative direction as the support portion is lowered.

  FIG. 9 shows a conceptual graph in which the horizontal axis represents the time since the support unit 122 started to descend, and the vertical axis represents the voltage applied to the ESC electrode 119. Before the holding sheet 3 comes into contact with the stage 111, a low voltage is applied to the ESC electrode 119, and the applied voltage increases as the support area 122 moves down and the contact area between the holding sheet 3 and the stage 111 increases. To do. Thereby, generation | occurrence | production of the wrinkle of the holding sheet 3 is further suppressed.

(Third embodiment)
In the present embodiment, after the bending portion of the holding sheet 3 comes into contact with the stage 111 and before the outer peripheral portion 3c of the holding sheet 3 comes into contact with the stage 111, the first implementation is performed except that voltage application to the ESC electrode 119 is started. It is the same as the form.

  FIG. 10 shows a conceptual graph in which the horizontal axis represents the time since the support unit 122 started to descend, and the vertical axis represents the voltage applied to the ESC electrode 119. The holding sheet 3 is adsorbed almost simultaneously with the contact with the stage 111. Therefore, the holding sheet 3 is adsorbed to the stage 111 without wrinkles.

  The plasma processing apparatus of the present invention is useful as an apparatus for plasma processing a substrate held on a carrier.

  1: substrate, 2: frame, 2a: notch, 2b: corner cut, 3: holding sheet, 3a: adhesive surface, 3b: non-adhesive surface, 3c: outer peripheral portion, 10: transport carrier, 100: plasma processing apparatus, 103 : Vacuum chamber, 103a: gas inlet, 103b: exhaust port, 108: dielectric member, 109: antenna (plasma source), 110A: first high frequency power source, 110B: second high frequency power source, 111: stage, 112 : Process gas source (gas supply means), 113: Ashing gas source, 114: Depressurization mechanism, 115: Electrode layer, 116: Metal layer, 117: Support layer, 118: Outer part, 119: ESC electrode, 120: High frequency electrode 121: lifting rod, 122: support portion, 122a: upper end surface, 123A, 123B: lifting mechanism, 124: cover, 124W: window portion, 125: Medium circulation apparatus, 126: DC power supply, 127: refrigerant passage, 128: controller

Claims (8)

A plasma processing apparatus for performing plasma processing on a substrate held on a carrier,
The transport carrier includes a holding sheet and a frame disposed on an outer peripheral portion of the holding sheet,
The substrate is held by the holding sheet;
The plasma processing apparatus includes:
A reaction chamber;
A stage disposed inside the reaction chamber for mounting the transport carrier;
An electrostatic attraction mechanism comprising an electrode provided inside the stage;
A support section for supporting the transport carrier between a mounting position on the stage and a delivery position spaced upward from the stage;
An elevating mechanism for elevating the support part with respect to the stage,
When the support unit is lowered and the transport carrier is mounted on the stage,
The plasma processing apparatus, wherein the electrostatic adsorption mechanism starts applying a voltage to the electrode unit before the outer peripheral portion of the holding sheet contacts the stage.   The plasma processing apparatus according to claim 1, wherein the electrostatic adsorption mechanism starts applying a voltage to the electrode unit before the holding sheet contacts the stage.   The plasma processing apparatus according to claim 1, wherein after the holding sheet comes into contact with the stage and before the outer peripheral portion comes into contact with the stage, the electrostatic adsorption mechanism starts applying a voltage to the electrode unit. .   The plasma processing apparatus according to any one of claims 1 to 3, wherein the electrostatic adsorption mechanism increases an absolute value of a voltage applied to the electrode part as the support part is lowered. A plasma processing method for carrying a plasma processing on a substrate by mounting a carrier on which a substrate is held on a stage provided in a plasma processing apparatus,
The transport carrier includes a holding sheet and a frame disposed on an outer peripheral portion of the holding sheet,
The substrate is held by the holding sheet;
Supporting the transport carrier on a support portion capable of moving up and down with respect to the stage at a transfer position away from the stage upward;
Lowering the support and mounting the transport carrier at a mounting position on the stage;
Applying a voltage to the electrode portion of the electrostatic adsorption mechanism provided inside the stage, and
The plasma processing method of starting application of the voltage to the said electrode part, before the said outer peripheral part of the said holding sheet contacts the said stage.   The plasma processing method according to claim 5, wherein application of a voltage to the electrode unit is started before the holding sheet contacts the stage.   The plasma processing method according to claim 5, wherein after the holding sheet comes into contact with the stage, application of a voltage to the electrode part is started before the outer peripheral part comes into contact with the stage.   The plasma processing method as described in any one of Claims 5-7 which makes the absolute value of the voltage applied to the said electrode part increase with the fall of the said support part.

Images