Plasma processing apparatus and plasma processing method

Abstract

To improve the yield of products when a substrate held on a holding sheet is subjected to plasma processing.SOLUTION: A plasma processing apparatus includes: a chamber; a plasma generation part which generates plasma in the chamber; a stage 111 which is provided inside the chamber and has a mounting surface on which a transfer carrier 10 is mounted; an imaging part 131 which is disposed outside the chamber and images an imaging area from a first direction crossing the mounting surface through a window part 130 provided in a side face of the chamber, the imaging area including an opposing area that is an inner peripheral side wall of a frame 2 of the transfer carrier 10 mounted on the stage 111 and that is an area opposing the window part 130; a control part which controls the plasma generation part and the imaging part; and a determination part which determines, based on imaging data imaged by the imaging part 131, whether the mounted state of the transfer carrier 10 is good or bad.SELECTED DRAWING: Figure 4E

Description

Technical Field

[0001] The present invention relates to a plasma processing apparatus and a plasma processing method, and particularly to a plasma processing method for plasma-processing a substrate held by a holding sheet.

Background Art

[0002] As a method of dicing a substrate, plasma dicing is known in which a substrate on which a mask is formed is subjected to plasma etching to be divided into individual chips. Patent Document 1 teaches that in order to improve the handleability of a substrate in conveyance and the like, the substrate is placed on a stage provided in a plasma processing apparatus while being held by a conveyance carrier including a frame and a holding sheet covering the opening thereof, and plasma processing is performed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The holding sheet has a small thickness and is easily bent. Therefore, the conveyance carrier holding the substrate may be placed on the stage with wrinkles in the holding sheet. When plasma processing is performed with wrinkles remaining in the holding sheet, abnormal discharge may occur at the wrinkled portion, or the temperature of the wrinkled portion may rise, making it difficult to perform plasma processing normally.

[0005] Plasma processing is usually performed while placing a transfer carrier on a stage and adsorbing it to the stage by an electrostatic adsorption mechanism called an electrostatic chuck. At this time, the holding sheet holding the substrate may be placed on the stage in a wrinkled state. Due to the wrinkles generated in the holding sheet, the holding sheet is adsorbed to the stage in a state where a part thereof is lifted from the stage. Therefore, the contact between the substrate and the stage via the holding sheet becomes insufficient.

[0006] When plasma processing is performed in a state where the contact between the substrate and the stage via the holding sheet is insufficient, etching of the substrate becomes non-uniform, resulting in variations in the processed shape and unprocessed portions. Furthermore, local temperature rise of the substrate or abnormal discharge may occur. There is also a concern that the substrate, the holding sheet, and even the ESC electrode constituting the electrostatic chuck may be damaged due to this temperature rise or abnormal discharge. As a result, the yield of the product decreases.

Means for Solving the Problems

[0007] One aspect of the present invention is a plasma processing apparatus for performing plasma processing on a substrate held by a transfer carrier including a frame and a holding sheet, the plasma processing apparatus including: a chamber; a plasma generation unit that generates plasma in the chamber; a stage provided in the chamber and having a mounting surface on which the transfer carrier is mounted; an imaging unit that is disposed outside the chamber and images an imaging region including a facing region, which is an inner peripheral side wall of the frame of the transfer carrier mounted on the stage and faces the window portion, from a first direction intersecting the mounting surface, through a window portion provided on a side surface of the chamber; a control unit that controls the plasma generation unit and the imaging unit; and a determination unit that determines a mounting state of the transfer carrier based on imaging data imaged by the imaging unit.

[0008] Another aspect of the present invention is a plasma processing method including: a placing step of placing a substrate held by a transfer carrier including a frame and a holding sheet on a stage of a plasma processing apparatus including a chamber, a plasma generation unit that generates plasma in the chamber, and a stage provided in the chamber and having a placement surface on which the transfer carrier is placed; and a determination step of determining a placement state of the transfer carrier. The determination step includes an imaging step of imaging the transfer carrier placed on the stage. The imaging step is a step of imaging an imaging region including a facing region, which is an inner peripheral side wall of the frame of the transfer carrier placed on the stage and faces the window portion, through a window portion provided on a side surface of the chamber from a first direction intersecting the placement surface, and in the determination step, the placement state of the transfer carrier is determined based on imaging data imaged in the imaging step.

Advantages of the Invention

[0009] According to the present invention, after confirming the contact state between the substrate and the stage via the holding sheet, plasma processing is executed, so that the yield of the product is improved.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 4E

Figure 4F

Embodiments for Carrying Out the Invention

[0011] A plasma processing apparatus according to an embodiment of the present invention is a plasma processing apparatus that performs plasma processing on a substrate held by a transfer carrier including a frame and a holding sheet, and includes a chamber, a plasma generation unit that generates plasma in the chamber, a stage provided in the chamber and having a mounting surface on which the transfer carrier is mounted, an imaging unit that is disposed outside the chamber and images an imaging region including a facing region that is an inner peripheral side wall of the frame of the transfer carrier mounted on the stage and faces the window portion provided on the side surface of the chamber from a first direction intersecting the mounting surface, a control unit that controls the plasma generation unit and the imaging unit, and a determination unit that determines the mounting state of the transfer carrier based on imaging data imaged by the imaging unit.

[0012] The determination of the placement state of the transfer carrier by the determination unit is performed based on imaging data obtained by imaging the placement state of the transfer carrier on the stage. The determination of the placement state can be performed based on the state of the inner peripheral side wall of the frame of the transfer carrier. The imaging unit images the placement state of the transfer carrier including the inner peripheral side wall of the frame from a first direction slightly inclined from the placement surface (main surface of the substrate) of the transfer carrier. When the material of the frame is, for example, a metal material, since it reflects light well, it is easy to distinguish the frame from the substrate or the holding sheet by image analysis from the imaging data. Here, when a part of the substrate or the holding sheet is lifted from the stage, when viewed from the first direction slightly inclined from the placement surface, the inner peripheral side wall of the frame is hidden by the shadow of the lifted substrate or holding sheet, making it difficult to identify the frame in the imaging data. Therefore, based on the state of the inner peripheral side wall of the frame in the imaging data, the placement state of the transfer carrier can be easily determined.

[0013] Therefore, the first direction can be set such that the angle formed by the first direction and the placement surface is an angle at which, when the holding sheet or the substrate has a separation region lifted and separated from the placement surface, at least a part of the imaging of the opposing region by the imaging unit is obstructed by the holding sheet or the substrate in the separation region.

[0014] The determination unit determines the placement state of the transfer carrier based on the information of the opposing region included in the imaging data. The determination unit determines, for example, whether the placement state of the transfer carrier corresponds to either the first state or the second state. The first state is when the placement is good, and the second state is when there is a poor placement. For example, if the area of the opposing region in the imaging region is equal to or greater than a predetermined value, it can be determined that the placement state is in the first state where the placement is good, and if it is less than the predetermined value, it can be determined that the placement state is in the second state with a poor placement. The information of the opposing region may include information such as the area of the opposing region, the brightness of the opposing region, and the shape.

[0015] Further, the determination unit may determine the placement state of the transfer carrier based on the information on the substrate surface included in the imaging data. Examples of the information on the substrate surface used for the determination include the reflection state of light on the substrate surface and the distortion of the pattern formed on the substrate surface. Specifically, when the placement state of the transfer carrier is defective and wrinkles are generated in the holding sheet, the reflected light on the substrate surface may increase due to the wrinkles. Further, when the placement state of the transfer carrier is defective and wrinkles are generated in the holding sheet, the pattern formed on the substrate surface is distorted due to the wrinkles.

[0016] When the determination unit determines that the placement state is the first state (good), the control unit causes the plasma generation unit to generate plasma. Plasma processing is performed using the generated plasma. On the other hand, when the determination unit determines that the placement state is the second state (defective), the control unit, for example, after performing a placement state improvement process, attempts to place the transfer carrier on the stage again. After the improvement process, the control unit causes the imaging unit to image the imaging area again and causes the determination unit to determine the placement state of the transfer carrier based on the imaging data again. When the determination unit determines that the placement state is the first state (good) in the re-determination, the control unit causes the plasma generation unit to generate plasma.

[0017] In this way, by determining the placement state based on the information on the opposing area in the imaging data, it is possible to suppress performing plasma processing in a state where there are separation areas such as wrinkles or lifting in the holding sheet, and improve the product yield.

[0018] Examples of the improvement process after the placement state is determined to be the second state (defective) include a method of repeatedly generating and stopping the suction force by the suction mechanism when using a suction mechanism that generates a suction force on the placement surface when fixing the transfer carrier to the stage. The generation and stop of the suction force may be repeated in a state where the plasma generation unit generates plasma.

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0020] First, an embodiment of the carrier used in the present invention will be described with reference to FIGS. 1(a) and (b). FIG. 1(a) is a top view schematically showing a substrate 1 and a carrier 10 for holding the same, and FIG. 1(b) is a cross-sectional view taken along line B-B shown in FIG. 1(a) of the substrate 1 and the carrier 10. As shown in FIG. 1(a), the carrier 10 includes a frame 2 and a holding sheet 3. The outer peripheral portion of the holding sheet 3 is fixed to the frame 2. The substrate 1 is adhered to the holding sheet 3 and held by the carrier 10. In FIG. 1, the case where both the frame 2 and the substrate 1 are substantially circular is illustrated, but the present invention is not limited thereto.

[0021] (Substrate) The substrate 1 is an object to be subjected to plasma treatment. The substrate 1 is produced, for example, by forming a circuit layer such as a semiconductor circuit, an electronic component element, or MEMS on one surface of a main body portion, and then grinding the back surface of the main body portion on the side opposite to the circuit layer to reduce the thickness. By singulating the substrate 1, an electronic component (not shown) having the above circuit layer can be obtained.

[0022] The size of the substrate 1 is not particularly limited. For example, the maximum diameter is about 50 mm to 300 mm. The thickness of the substrate 1 is usually about 25 to 150 μm, which is very thin. Therefore, the substrate 1 itself has almost no rigidity (self-supporting property). Therefore, the outer peripheral portion of the holding sheet 3 is fixed to the substantially flat frame 2, and the substrate 1 is adhered to this holding sheet 3. This facilitates handling such as transporting the substrate 1. The shape of the substrate 1 is not particularly limited either. For example, it may be circular or rectangular. Further, the substrate 1 may be provided with a notch such as an orientation flat (orifla) or a notch (both not shown).

[0023] The material of the main body of the substrate is not particularly limited, and examples include semiconductors, dielectrics, metals, or laminates thereof. Examples of semiconductors include silicon (Si), gallium arsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC), etc. Examples of dielectrics include resin films such as polyimide, low dielectric constant films (Low-k films), silicon dioxide (SiO2), silicon nitride (Si3N4), lithium tantalate (LiTaO3), lithium niobate (LiNbO3), etc.

[0024] On the surface of the substrate 1 that is not adhered to the holding sheet 3, a mask is formed in a desired shape (not shown). The portion where the mask is formed is protected from plasma etching. The portion where the mask is not formed can be etched from its front surface to the back surface by plasma. As the mask, for example, a resist mask formed by exposing and developing a resist film can be used. Also, the mask may be formed, for example, by opening a resin film or resin film formed on the surface of the substrate 1 by laser scribing.

[0025] (Frame) The frame 2 is a frame body having an opening with an area equal to or larger than the entire substrate 1, and has a predetermined width and a substantially constant thin thickness. The frame 2 has rigidity sufficient to be transported while holding the holding sheet 3 and the substrate 1.

[0026] The shape of the opening of the frame 2 is not particularly limited, and may be, for example, circular, rectangular, or polygonal such as hexagonal. 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. On one surface of the frame 2, the outer peripheral edge vicinity of one surface of the holding sheet 3 is adhered.

[0027] (Holding Sheet) The holding sheet 3 has, for example, a surface with an adhesive (adhesive surface 3a) and a surface without an adhesive (non - adhesive surface 3b). The outer peripheral edge of the adhesive surface 3a is adhered to one surface of the frame 2 and covers the opening of the frame 2. Also, the substrate 1 is adhered to the portion of the adhesive surface 3a that is exposed from the opening of the frame 2.

[0028] The adhesive surface 3a preferably consists of an adhesive component whose adhesive force decreases upon irradiation with ultraviolet rays (UV). This is because by performing UV irradiation after dicing, the singulated substrates (electronic components) can be easily peeled off from the adhesive surface 3a and are easy to pick up. For example, the holding sheet 3 can be obtained by applying a UV - curable acrylic adhesive to one side of a film - shaped substrate to a thickness of 5 - 20 μm.

[0029] The material of the film - shaped substrate is not particularly limited, and examples include thermoplastic resins such as polyolefins like polyethylene and polypropylene, and polyesters like polyethylene terephthalate. The substrate may be blended with various additives such as rubber components (e.g., ethylene - propylene rubber (EPM), ethylene - propylene - diene rubber (EPDM), etc.) for adding stretchability, plasticizers, softening agents, antioxidants, and conductive materials. Also, the above - mentioned thermoplastic resin may have a functional group that exhibits a photopolymerization reaction such as an acrylic group. The thickness of the substrate is, for example, 50 - 150 μm. During plasma treatment, the transfer carrier 10 is placed on the stage such that the stage and the non - adhesive surface 3b are in contact.

[0030] (Plasma treatment apparatus) Next, with reference to FIG. 2, the basic structure of the plasma treatment apparatus 100 according to an embodiment of the present invention will be described. FIG. 2 schematically shows a cross - section of the basic structure of the plasma treatment apparatus 100.

[0031] The plasma processing apparatus 100 includes a stage 111. The transfer carrier 10 is mounted on the stage 111 such that the surface holding the substrate 1 of the holding sheet 3 faces upward. The stage 111 has a size large enough to place the entire transfer carrier 10 thereon. Above the stage 111, a cover 124 having a window portion 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.

[0032] The stage 111 and the cover 124 are disposed in the processing chamber (vacuum chamber 103). The vacuum chamber 103 is generally cylindrical with an open upper portion, and the upper opening is closed by a dielectric member 108 which is a lid body. Examples of the material constituting the vacuum chamber 103 include aluminum, stainless steel (SUS), and aluminum anodized on the surface. Examples of the material constituting the dielectric member 108 include dielectric materials such as yttrium oxide (Y2O3), aluminum nitride (AlN), alumina (Al2O3), and quartz (SiO2). Above the dielectric member 108, an antenna 109 as an upper electrode is disposed. The antenna 109 is electrically connected to a first high-frequency power supply 110A. The stage 111 is disposed on the bottom side in the vacuum chamber 103.

[0033] A gas inlet 103a is connected to the vacuum chamber 103. A process gas source 112 and an ashing gas source 113, which are sources of plasma generation gas, are respectively connected to the gas inlet 103a by piping. Further, an exhaust port 103b is provided in the vacuum chamber 103, and a decompression mechanism 114 including a vacuum pump for exhausting the gas in the vacuum chamber 103 to reduce the pressure is connected to the exhaust port 103b.

[0034] On the side of the transfer carrier 10, a window 130 is provided on the side surface of the vacuum chamber 103. The window 130 is made of, for example, transparent glass, and the state in which the transfer carrier 10 is placed on the stage 111 can be visually recognized through the window 130.

[0035] The imaging unit 131 is disposed close to the window 130 of the vacuum chamber 103. The imaging unit 131 is, for example, a CCD camera. The imaging unit 131 images the transport carrier 10 through the window 130 and acquires imaging data. The imaging region includes an opposing region that is the inner peripheral side wall of the frame 2 and faces the window 130. In the imaging data, by performing image analysis on the opposing region in particular of the imaging region, it is possible to determine whether the placement state of the transport carrier 10 on the stage 111 is good or not. The determination of whether the placement state is good or not can be performed by a determination unit provided in a control unit described later.

[0036] 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. The outer peripheral portion 118 is made of a metal having conductivity and etching resistance, and protects the electrode layer 115, the metal layer 116, and the base 117 from plasma. An annular outer peripheral ring 129 is disposed on the upper surface of the outer peripheral portion 118. The outer peripheral ring 129 serves to protect the upper surface of the outer peripheral portion 118 from plasma. The electrode layer 115 and the outer peripheral ring 129 are made of, for example, the above-described dielectric material.

[0037] Inside the electrode layer 115, an ESC electrode 119 that constitutes an electrostatic adsorption mechanism and a high-frequency electrode portion 120 electrically connected to the second high-frequency power supply 110B are disposed. A DC power supply 126 is electrically connected to the ESC electrode 119. The electrostatic adsorption mechanism is constituted by the ESC electrode 119 and the DC power supply 126. By the electrostatic adsorption mechanism, the holding sheet 3 is pressed against and fixed to the stage 111. Hereinafter, the case where the electrostatic adsorption mechanism is provided as a fixing mechanism for fixing the holding sheet 3 to the stage 111 will be described as an example, but the present invention is not limited thereto. The fixing of the holding sheet 3 to the stage 111 may be performed by a clamp (not shown).

[0038] The metal layer 116 is composed of, for example, aluminum with an anodized coating formed on its surface. A refrigerant flow path 127 is formed within the metal layer 116. The refrigerant flow path 127 cools the stage 111. When the stage 111 is cooled, the holding sheet 3 mounted on the stage 111 is cooled, and the cover 124 that is in contact with a part of the stage 111 is also cooled. As a result, it is possible to suppress damage to the substrate 1 and the holding sheet 3 caused by heating during plasma processing. The refrigerant within the refrigerant flow path 127 is circulated by a refrigerant circulation device 125.

[0039] In the vicinity of the outer periphery of the stage 111, a plurality of support portions 122 penetrating the stage 111 are arranged. The support portions 122 are driven to move up and down by a lifting mechanism 123A. When the transfer carrier 10 is transferred into the vacuum chamber 103, it is delivered to the support portions 122 that have risen to a predetermined position. The support portions 122 support the frame 2 of the transfer carrier 10. When the upper end surface of the support portion 122 descends to a level below that of the stage 111, the transfer carrier 10 is mounted at a predetermined position on the stage 111.

[0040] A plurality of lifting rods 121 are connected to the end of the cover 124, enabling the cover 124 to move up and down. The lifting rods 121 are driven to move up and down by a lifting mechanism 123B. The operation of moving the cover 124 up and down by the lifting mechanism 123B can be performed independently of the lifting mechanism 123A.

[0041] The elevating rod 121 and the elevating mechanism 123B constitute a relative position changing unit, and change the relative distance between the cover 124 and the stage 111. For example, the determination by the determination unit of the placement state of the transfer carrier 10 on the stage 111 can be performed in a state where the distance between the cover 124 and the stage 111 is the first distance d1 with the cover 124 raised so as not to interfere with the imaging of the opposing region by the imaging unit 131. As a result of the determination, when it is determined that the placement state is the first state (good), the relative position changing unit changes the distance between the cover 124 and the stage 111 to the second distance d2 by lowering the cover 124. Thereafter, plasma processing is performed in a state where the distance between the cover 124 and the stage 111 is the second distance d2. However, the method of changing the distance by the relative position changing unit is not limited to the method using the elevating rod 121.

[0042] The dielectric member 108, the antenna 109, the first high-frequency power source 110A, the second high-frequency power source 110B, the process gas source 112, the pressure reducing mechanism 114, and the high-frequency electrode unit 120 constitute a plasma generation unit.

[0043] The control device 128 controls the operations of the elements constituting the plasma processing apparatus 100 including the first high-frequency power source 110A, the second high-frequency power source 110B, the process gas source 112, the ashing gas source 113, the pressure reducing mechanism 114, the refrigerant circulation device 125, the elevating mechanism 123A, the elevating mechanism 123B, and the electrostatic adsorption mechanism. The control device 128 also has a determination unit, and determines the quality of the placement state of the transfer carrier 10 on the stage 111 based on the imaging data acquired by the imaging unit 131.

[0044] (Plasma processing method) Next, the basic steps of the plasma processing method according to the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a flowchart showing some steps of the plasma processing method.

[0045] Figs. 4A to 4F are conceptual diagrams showing the positional relationship between the cover and the stage in each step of the plasma treatment method. In Figs. 4A to 4F, for ease of understanding the invention, descriptions of the outer peripheral portion 118, the outer peripheral ring 129, and the gas introduction path are omitted.

[0046] A plasma treatment method according to an embodiment of the present invention includes placing a substrate held by a transport carrier including a frame and a holding sheet on a stage of a plasma treatment apparatus including a chamber, a plasma generation unit that generates plasma in the chamber, and a stage provided in the chamber and having a placement surface on which the transport carrier is placed, and a determination step of determining the placement state of the transport carrier. The determination step includes an imaging step of imaging the transport carrier placed on the stage. The imaging step is a step of imaging an imaging region including a facing region, which is an inner wall of the frame of the transport carrier placed on the stage and faces the window portion, through a window portion provided on a side surface of the chamber, from a first direction intersecting the placement surface, the imaging region being disposed outside the chamber. In the determination step, the placement state of the transport carrier is determined based on the imaging data captured in the imaging step.

[0047] (1) Preparation step First, a transport carrier 10 is prepared. The transport carrier 10 is obtained by attaching and fixing a holding sheet 3 to one surface of a frame 2. At this time, as shown in Fig. 1(b), the adhesive surface 3a of the holding sheet 3 is opposed to the frame. Next, the substrate 1 is held by the transport carrier 10 by attaching the substrate 1 to the adhesive surface 3a of the holding sheet 3.

[0048] (2) Loading step Next, the transport carrier 10 holding the substrate 1 is loaded into the vacuum chamber 103.

[0049] Fig. 4A shows the positional relationship between the cover 124 and the stage 111 before loading the transport carrier. As shown in Fig. 4A, the lifting rod 121 and the support portion 122 are in the lowered positions.

[0050] Drive the lifting rod 121 and the support part 122 to raise the cover 124 to a predetermined position in the vacuum chamber 103 and wait with the support part 122 in the raised state. FIG. 4B shows the positional relationship between the cover 124 and the stage 111 at this time. At this time, the distance between the cover 124 and the stage 111 is the first distance d1.

[0051] Subsequently, open a shutter (not shown), and through the transfer arm, the transfer carrier 10 held by the transfer arm is carried into the vacuum chamber 103. When the transfer carrier 10 reaches a predetermined position above the stage 111, the transfer carrier 10 is delivered to the support part 122. The transfer carrier 10 is placed on the upper end surface of the support part 122 so that the surface holding the substrate 1 of the holding sheet 3 faces upward. FIG. 4C shows the positional relationship between the cover 124 and the stage 111 at this time.

[0052] (3) Placement step When the transfer carrier 10 is delivered to the support part 122, retract the transfer arm 221, close the shutter, and make the vacuum chamber 103 in a sealed state. Then, lower the support part 122. By lowering the upper end surface of the support part 122 below the same level as the stage 111, the transfer carrier 10 is placed on the stage 111. FIG. 4D shows the positional relationship between the cover 124 and the stage 111 at this time. Since the cover 124 is not lowered, the distance between the cover 124 and the stage 111 remains the first distance d1.

[0053] Subsequently, fix the transfer carrier 10 placed on the stage 111 on the stage 111. When the stage 111 is provided with the ESC electrode 119, by applying a voltage to the ESC electrode 119, an adsorption force is generated between the holding sheet 3 of the transfer carrier 10 and the stage 111, and the holding sheet 3, and thus the transfer carrier 10 can be fixed to the stage 111.

[0054] The ESC electrode 119 is roughly classified into two types: a unipolar type and a bipolar type. The unipolar ESC electrode 119 includes at least one electrode. When two or more electrodes are included in the unipolar ESC electrode 119, voltages of the same polarity are applied to all of them. The electrostatic adsorption mechanism provided with the unipolar ESC electrode 119 utilizes the Coulomb force as the adsorption mechanism. By applying a voltage to the ESC electrode 119, charges due to dielectric polarization are induced on the surface of the stage 111 made of a dielectric, and the holding sheet 3 placed on the stage 111 is charged. As a result, a Coulomb force acts between the charges induced on the surface of the stage 111 and the charged holding sheet 3, and the transfer carrier 10 is adsorbed to the stage 111. In addition, in order to charge the holding sheet 3, plasma may be generated in the vacuum chamber 103 and the holding sheet 3 may be exposed to the generated plasma.

[0055] On the other hand, the bipolar ESC electrode 119 includes a positive electrode and a negative electrode, and voltages of different polarities are applied to the positive electrode and the negative electrode, respectively. As the bipolar ESC electrode 119, for example, a comb-shaped electrode is used. A voltage of V1 is applied to the positive electrode from the DC power supply 126, and a voltage of -V1 is applied to the negative electrode from the DC power supply 126.

[0056] As the adsorption mechanism of the electrostatic adsorption mechanism provided with the bipolar ESC electrode 119, there are cases where the Coulomb force is utilized and cases where the Johnson-Larbeck force is utilized. Depending on the adsorption mechanism, the structure of the ESC electrode 119 and the material (for example, ceramics) constituting the ESC electrode 119 are appropriately selected. In any case of the adsorption mechanism, by applying voltages of different polarities to the positive electrode and the negative electrode, respectively, an adsorption force is generated between the ESC electrode and the holding sheet 3, and the transfer carrier 10 can be adsorbed to the stage 111. Note that, in the case of the bipolar type, unlike the unipolar type, it is not necessary to charge the holding sheet 3 for adsorption.

[0057] The bipolar ESC electrode can also function as a unipolar type depending on the method of applying voltages to the positive electrode and the negative electrode. Specifically, it can be used as a unipolar ESC electrode by applying voltages of the same polarity to the positive electrode and the negative electrode.

[0058] When the ESC electrode 119 is bipolar, after the carrier 10 is transferred to the support portion 122, a voltage is applied from the DC power supply 126 to the ESC electrode 119. As a result, the holding sheet 3 comes into contact with the stage 111 and is simultaneously adsorbed to the stage 111, and the holding sheet 3 is fixed to the stage 111. Note that the application of the voltage to the ESC electrode 119 may be started after the holding sheet 3 is placed on (comes into contact with) the stage 111.

[0059] (4) Determination step After the placement step, a determination step for determining the placement state of the carrier is performed. Here, through the window 130 provided on the side surface of the chamber, the placement state of the carrier 10 in the vacuum chamber 103 is photographed using the imaging unit 131, and the imaging data is analyzed. Thereby, the placement state of the holding sheet 3 on the stage 111, and thus the placement state of the substrate 1 on the stage 111 via the holding sheet 3, is determined.

[0060] For example, as shown in FIG. 4D, the imaging unit 131 is disposed at a position lateral to the carrier 10 in a state of being placed on the stage 111, and photographs the carrier 10 from an angle slightly inclined from the placement surface of the carrier (the main surface of the substrate 1). In particular, the imaging unit 131 photographs a region on the inner peripheral side wall of the frame 2 of the carrier 10 that faces the window portion 130. The imaging angle and imaging range of the imaging unit 131 are adjusted so that the inner peripheral side wall of the frame is included in the imaging data. More specifically, the imaging direction (first direction) of the imaging unit 131 is such that the angle formed by the first direction and the placement surface is an angle such that when the holding sheet or the substrate has a separated region where it floats and separates from the placement surface, at least a part of the facing region by the imaging unit is blocked by the holding sheet or the substrate in the separated region. The angle formed by the placement surface of the carrier and the first direction may be, for example, in the range exceeding 0° and equal to or less than 30°.

[0061] As shown in FIG. 4D, when there is no lifting from the stage 111 on the substrate or the holding sheet and the placement state of the transfer carrier is good (first state), the imaging data includes information on the inner peripheral side wall of frame 2. However, for example, as shown in FIG. 4E, when wrinkles occur in a part of the holding sheet and a part of the holding sheet is lifted from the stage 111 (second state), at least a part of the inner peripheral side wall of the frame is hidden by the lifted part and does not appear in the imaging data. Therefore, by obtaining the region (opposing region) corresponding to the inner peripheral side wall of the frame from the imaging data through image analysis, the placement state of the transfer carrier can be determined. For example, the area of the region (opposing region) corresponding to the inner peripheral side wall of the frame in the imaging data is obtained. If the area is equal to or greater than a predetermined value, the placement state is the first state (good), and if it is less than the predetermined value, the placement state is determined to be the second state (bad).

[0062] Also, as shown in FIG. 4E, when the substrate is thin and flexible, if wrinkles occur in the holding sheet, wrinkles may also occur in the substrate held at the wrinkled part of the holding sheet. When wrinkles occur in the substrate, the reflection state of light on the substrate surface changes, or distortion occurs in the pattern formed on the substrate surface. Therefore, by obtaining information on the substrate surface from the imaging data through image analysis, the placement state of the transfer carrier can be determined.

[0063] When it is determined that the placement state of the transfer carrier 10 on the stage 111 is the first state (good), the process proceeds to the plasma etching process described later. On the other hand, when it is determined that the placement state of the transfer carrier 10 on the stage 111 is the second state (bad), the transfer carrier 10 is carried out of the vacuum chamber 103, and then the placement process is attempted again. Alternatively, the support portion 122 is raised again, and the placement process is attempted again from the state where the transfer carrier 10 is separated from the stage 111. In the retry, the support portion 122 may be slightly raised or lowered while the support portion 122 is being raised or lowered. Thereby, the wrinkles of the holding sheet 3 are eliminated, and the lifting of the holding sheet is more easily eliminated.

[0064] When it is determined in the determination step that the placement state of the transfer carrier 10 is in the second state (defective), before the transfer carrier 10 is carried out of the vacuum chamber 103, an improvement step for the placement state may be performed. In the improvement step, for example, the application of voltage to the ESC electrode 119 is intermittently performed, and the generation and stop of the adsorption force are repeated a plurality of times. With the plasma generated in the vacuum chamber 103, the generation and stop of the adsorption force may be repeated a plurality of times. The applied voltage V1 (the absolute value of the voltage applied to the positive and negative electrodes) to the ESC electrode 119 in the improvement step is, for example, about 2500 V, and for example, the application of voltage for 1 second and the non-application of voltage for 1 second are repeated. When generating plasma, for example, Ar gas is supplied into the vacuum chamber 103, and high-frequency power with a frequency of 13.56 MHz and a power of 100 to 500 W is supplied to the antenna 109.

[0065] After the improvement step, the determination step is performed again to determine the placement state of the transfer carrier. In the determination step after the improvement step, when it is determined that the placement state of the transfer carrier 10 on the stage 111 is in the first state (good), the plasma etching step described later is proceeded to. On the other hand, when it is also determined in the determination step after the improvement step that the placement state of the transfer carrier 10 on the stage 111 is in the second state (defective), the improvement step may be performed again.

[0066] If it is determined that the placement state is in the second state (defective) even after a plurality of improvement steps, the transfer carrier 10 is carried out of the vacuum chamber 103, and then the placement step is attempted again. Alternatively, the support portion 122 is raised again, and the placement step is attempted again from the state where the transfer carrier 10 is separated from the stage 111.

[0067] In the determination step, the determination of the placement state of the transfer carrier is performed in a state where the cover 124 is raised so that the imaging of the opposing area by the imaging unit 131 is not obstructed by the cover 124, and the distance between the cover 124 and the stage 111 is the first distance d1. In this case, since the determination of the placement state of the transfer carrier is performed in a state where the cover is sufficiently separated from the transfer carrier, it is possible to prevent the occurrence of subsequent processing errors caused by a defective placement state. For example, it is possible to avoid a transfer error due to contact with the cover during unloading when the placement state is defective. As a result, the yield and production efficiency of the substrate can be further improved.

[0068] (5) Plasma treatment step In the determination step, when it is determined that the above placement state is good, the lifting rod 121 is driven to lower the cover 124 to a predetermined position. As a result, the distance between the cover 124 and the stage 111 is changed to a second distance d2 that is smaller than the first distance d1. FIG. 4F shows the positional relationship between the cover 124 and the stage 111 at this time. The second distance d2 is adjusted to a distance at which the cover 124 can cover the frame 2 without contacting the holding sheet 3. Thereby, a part of the portion of the frame 2 and the holding sheet 3 that does not hold the substrate 1 is covered by the cover 124, and the substrate 1 is exposed from the window portion 124W of the cover 124. The second distance d2 is not particularly limited, but is, for example, about 0.5 mm to 1.5 mm. The second distance d2 is the shortest distance between a part of the cover 124 that faces the holding sheet of the transfer carrier placed on the stage 111 and the stage 111.

[0069] The cover 124 has, for example, a donut shape with a substantially circular outer contour, and has a certain width and a thin thickness. The inner diameter of the cover 124 (the diameter of the window portion 124W) 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 transfer 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. The cover 124 is made of, for example, a dielectric such as ceramics (e.g., alumina, aluminum nitride, etc.) or quartz, or a metal such as aluminum or aluminum with an anodized surface.

[0070] When the support portion 122 and the cover 124 are arranged 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 pressure reducing 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 applied from the first high-frequency power source 110A to the antenna 109 to generate plasma P in the vacuum chamber 103. The generated plasma P is composed of ions, electrons, radicals, etc. The portion of the surface of the substrate 1 exposed from the resist mask formed thereon to the back surface is removed (etched) by the physicochemical reaction with the generated plasma P, and the substrate 1 is separated into individual pieces.

[0071] Here, high-frequency power of, for example, 100 kHz or more may be applied from the second high-frequency power source 110B to the high-frequency electrode portion 120. The incident energy of ions on the substrate 1 can be controlled by the high-frequency power applied from the second high-frequency power source 110B to the high-frequency electrode portion 120. When high-frequency power is applied to the high-frequency electrode portion 120, a bias voltage is generated on the surface of the stage 111, and the ions incident on the substrate 1 are accelerated by this bias voltage, increasing the etching rate.

[0072] The etching conditions (conditions for generating plasma) are set according to the material of the substrate 1 and the like. For example, when the substrate 1 is Si, plasma generated from sulfur hexafluoride (SF6) or the like as a raw material is generated in the vacuum chamber 103, and the substrate 1 is etched. In this case, for example, while supplying SF6 gas from the process gas source 112 at 100 to 800 sccm, the pressure of the vacuum chamber 103 is controlled to 10 to 50 Pa by the pressure reducing mechanism 114. At this time, high-frequency power with a frequency of 13.56 MHz and a power of 1000 to 5000 W is supplied to the antenna 109, and high-frequency power with a frequency of 100 kHz or more (for example, 400 to 500 kHz, or 13.56 MHz) and a power of 50 to 1000 W is supplied to the high-frequency electrode portion 120.

[0073] In order to suppress the temperature rise of the transfer carrier 10 during etching, it is preferable to set the temperature of the refrigerant circulated in the stage 111 to -20 to 20 °C by the refrigerant circulation device 125. Thereby, if the contact state between the holding sheet 3 and the stage 111 is good, the temperature of the holding sheet 3 during plasma processing is controlled to 60 °C or lower, for example. Therefore, thermal damage to the holding sheet 3 is suppressed.

[0074] In the case of plasma dicing, it is desirable that the surface of the substrate 1 exposed from the resist mask be etched vertically. In this case, as described above, an etching step using plasma of a fluorine-based gas such as SF6 and a protective film deposition step using plasma of a fluorocarbon gas such as perfluorocyclobutane (C4F8) may be alternately repeated.

[0075] After the substrate 1 is diced by etching, ashing is performed. A process gas for ashing (for example, oxygen gas, a mixed gas of oxygen gas and a gas containing fluorine, etc.) is introduced from an ashing gas source 113 into the vacuum chamber 103. On the other hand, evacuation is performed by a pressure reduction mechanism 114 to maintain the inside of 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 diced substrate 1 (electronic component) exposed from the window portion 124W of the cover 124 is completely removed.

[0076] (6) Unloading process When the ashing is completed, the gas in the vacuum chamber 103 is discharged, the shutter is opened, and the transfer carrier 10 holding the diced substrate 1 is unloaded from the plasma processing apparatus 100 by the transfer arm 221. The unloading process of the transfer carrier 10 may be performed in a procedure reverse to the procedure of mounting the substrate 1 on the stage 111 as described above. That is, after raising the cover 124 to a predetermined position, the applied voltage to the ESC electrode 119 is set to zero, the adsorption of the transfer carrier 10 to the stage 111 is released, and the support portion 122 is raised. After the support portion 122 is raised to a predetermined position, the transfer carrier 10 is unloaded.

Industrial applicability

[0077] The plasma processing method of the present invention is useful when performing plasma processing on a substrate held by a transfer carrier using a plasma processing apparatus.

Explanation of symbols

[0078] 1: Substrate, 1A: Outer peripheral portion, 1B: Central portion 2: Frame, 2a: Notch, 2b: Corner cut 3: Holding sheet, 3a: Adhesive surface, 3b: Non-adhesive surface 10: Transfer carrier 100: Plasma processing apparatus 103: Vacuum chamber, 103a: Gas inlet, 103b: Exhaust port, 108: Dielectric member, 109: Antenna, 110A: First high-frequency power source, 110B: Second high-frequency power source, 111: Stage, 112: Process gas source, 113: Ashing gas source, 114: Pressure reducing mechanism, 115: Electrode layer, 116: Metal layer, 117: Base, 118: Outer peripheral portion, 119: ESC electrode, 120: High-frequency electrode portion, 121: Lifting rod, 122: Support portion, 123A, 123B: Lifting mechanism, 124: Cover, 124W: Window portion, 125: Refrigerant circulation device, 126: DC power source, 127: Refrigerant flow path, 128: Control device, 129: Outer peripheral ring 130: Window (window portion), 131: Imaging unit

Claims

1. A plasma processing apparatus for performing plasma processing on a substrate held by a transport carrier including a frame and a holding sheet, the plasma processing apparatus comprising: a chamber; a plasma generation unit that generates plasma in the chamber; a stage provided in the chamber and having a placement surface on which the transport carrier is placed; an imaging unit disposed outside the chamber, imaging an imaging region including a facing region, which is an inner peripheral side wall of the frame of the transport carrier placed on the stage and faces the window portion, from a first direction intersecting the placement surface, through a window portion provided on a side surface of the chamber; a control unit that controls the plasma generation unit and the imaging unit; a determination unit that determines a placement state of the transport carrier based on imaging data imaged by the imaging unit. A plasma processing apparatus comprising:

2. The first direction is set such that when the holding sheet or the substrate has a separation region where it floats and separates from the placement surface, imaging of at least a part of the facing region by the imaging unit is hindered by the separation region. The determination unit determines the placement state of the transport carrier based on information of the facing region included in the imaging data. The plasma processing apparatus according to claim 1.

3. The imaging region includes a surface of the substrate held by the transport carrier. The determination unit determines the placement state of the transport carrier based on information of the surface included in the imaging data. The plasma processing apparatus according to claim 1.

4. When the determination unit determines that the placement state of the transport carrier is a first state, the control unit causes the plasma generation unit to generate plasma. When the determination unit determines that the placement state of the transport carrier is a second state, the plasma processing apparatus according to any one of claims 1 to 3, which causes an improvement process for the placement state to be performed.

5. After the improvement process, the control unit causes the imaging unit to image the imaging region again and the determination unit to determine the placement state of the transport carrier based on the imaging data. The plasma processing apparatus according to claim 4.

6. The plasma processing apparatus further includes an adsorption mechanism that generates an adsorption force on the placement surface. The improvement process includes repeatedly generating and stopping the adsorption force by the adsorption mechanism a plurality of times. The plasma processing apparatus according to claim 4 or 5.

7. Placing a substrate held by a transport carrier having a frame and a holding sheet on a stage of a plasma processing apparatus, the plasma processing apparatus including a chamber, a plasma generation unit that generates plasma in the chamber, and a stage provided in the chamber and having a placement surface on which the transport carrier is placed; A determination step of determining a placement state of the transport carrier; The determination step includes an imaging step of imaging the transport carrier placed on the stage; The imaging step is a step of imaging an imaging region including a facing region, which is an inner peripheral side wall of the frame of the transport carrier placed on the stage and is a region facing the window portion, from a first direction intersecting the placement surface, through a window portion provided on a side surface of the chamber and disposed outside the chamber; A plasma processing method for determining a placement state of the transport carrier based on imaging data captured in the imaging step in the determination step.

8. The first direction is set such that when the holding sheet or the substrate has a separation region where it floats and separates from the placement surface, imaging of at least a part of the facing region in the imaging step is hindered by the separation region; The plasma processing method according to claim 7, wherein in the determination step, the placement state of the transport carrier is determined based on information on the facing region included in the imaging data.

9. The imaging region includes a surface of the substrate held by the transport carrier; The plasma processing method according to claim 7, wherein in the determination step, the placement state of the transport carrier is determined based on information on the surface included in the imaging data.

Images