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 on which a transfer carrier 10 is mounted; a cover 124 which covers at least part of the transfer carrier mounted on the stage; a relative position change part which can change a relative distance between the cover 124 and the stage 111 into a first distance and a second distance less than the first distance; a determination part which determines whether the mounted state of the transfer carrier 10 is good or bad; and a control part. The determination part determines whether the mounted state is good or bad, in a state where the distance between the cover 124 and the stage 111 is the first distance, and plasma processing is applied in a state where the distance between the cover 124 and the stage 111 is the second distance.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 (wafer) on which a resist mask is formed is subjected to plasma etching to be divided into individual chips.

[0003] Patent Document 1 discloses a method of plasma-dicing a substrate, including steps of supplying a workpiece support portion into a processing chamber, disposing a substrate on a carrier support portion to form a workpiece, loading the workpiece onto the workpiece support portion, providing a cover ring disposed above the workpiece, generating plasma by a plasma source, and etching the workpiece by the generated plasma.

[0004] The substrate is usually adhesively fixed to a holding sheet provided with an adhesive for fixing the substrate on one side. The holding sheet is also called a dicing tape. The substrate is placed on a stage in a plasma processing apparatus in a state of being held by a transport carrier (carrier support portion) including the holding sheet and a frame disposed on the outer peripheral portion of the holding sheet for improving handling properties, and plasma processing is performed. In order to suppress the transport carrier from being directly exposed to plasma and damaged, a protective cover made of a dielectric covers the exposed portions of the frame and the holding sheet.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The larger the separation distance between the protective cover and the transport carrier, the more likely it is for discharge to occur in the space between the protective cover and the holding sheet, and the more likely it is for tape damage to occur. For this reason, the protective cover is arranged close to the transport carrier. The distance between the protective cover and the holding sheet is, for example, about 2 mm.

[0007] On the other hand, when fixing the transport carrier to the stage, a part of the substrate or the holding sheet may be lifted or fixed to the stage in a wrinkled state. If the protective cover is lowered with the substrate or the holding sheet floating, the protective cover may come into contact with the holding sheet and the tape may be damaged. In addition, when plasma treatment is performed with the substrate floating, the substrate may not be sufficiently cooled by the stage and become hot, or the wafer may be damaged. Also, the plasma etching may become non-uniform and the processing variation may increase.

Means for Solving the Problems

[0008] One aspect of the present invention is 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 including: a chamber; a plasma generation unit that generates plasma in the chamber; a stage provided in the chamber on which the transport carrier is placed; a cover that covers at least a part of the transport carrier placed on the stage; a relative position changing unit that can change the relative distance between the cover and the stage to a first distance and a second distance smaller than the first distance; a determination unit that determines the placement state of the transport carrier; and a control unit that controls the plasma generation unit and the relative position changing unit, wherein the determination unit determines the placement state in a state where the distance between the cover and the stage is the first distance, and the plasma processing is performed in a state where the distance between the cover and the stage is the second distance.

[0009] Another aspect of the present invention is to place a substrate held by a transport 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, a stage provided in the chamber on which the transport carrier is placed, and a cover that covers at least a part of the transport carrier in a state where the transport carrier is placed on the stage, and a determination step of determining the placement state of the transport carrier in a state where the distance between the cover and the stage is a first distance. When it is determined in the determination step that the placement state is a first state, the distance between the cover and the stage is changed to a second distance smaller than the first distance, and then plasma is generated in the chamber, and the generated plasma is irradiated onto the substrate to perform plasma processing. It relates to a plasma processing method.

Advantages of the Invention

[0010] According to the present invention, it is possible to suppress plasma processing from being performed in a state where a part of the substrate or the holding sheet floats from the stage, and the yield and production efficiency of the substrate are improved.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 4E

Figure 4F

Embodiments for Carrying Out the Invention

[0012] 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 on which the transfer carrier is placed, and a cover that covers at least a part of the transfer carrier placed on the stage. The plasma processing apparatus further includes a relative position changing unit that can change the relative distance between the cover and the stage to a first distance and a second distance smaller than the first distance, a determination unit that determines the placement state of the transfer carrier, and a control unit that controls the plasma generation unit and the relative position changing unit.

[0013] The determination unit determines the placement state of the transfer carrier in a state where the distance between the cover and the stage is the first distance. On the other hand, plasma processing is performed in a state where the distance between the cover and the stage is the second distance. That is, the determination of the placement state of the transfer carrier by the determination unit is performed in a state where the distance between the cover and the stage is larger than the state where plasma processing is performed, that is, in a state where the cover is sufficiently separated from the transfer carrier. Thereby, 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 are improved. The determination unit determines whether the placement state of the transfer carrier corresponds to either the first state or the second state. The first state is the case where the placement is good, and the second state is the case where there is a defective placement.

[0014] The determination of the placement state of the transfer carrier by the determination unit may be performed based on imaging data obtained by imaging the placement state of the transfer carrier on the stage. Preferably, the plasma processing apparatus further includes an imaging unit that images the transfer carrier placed on the stage. The determination unit can determine the placement state based on the imaging data imaged by the imaging unit in a state where the distance between the cover and the stage is the first distance.

[0015] In this case, the determination of the placement state may be performed based on the state of the inner peripheral side wall of the frame of the transfer carrier. For example, the imaging unit images the placement state of the transfer carrier including the inner peripheral side wall of the frame from a direction slightly inclined from the placement surface (main surface of the substrate) of the transfer carrier. When the material of the frame is a metal material, since it reflects light, 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 a direction slightly inclined from the main surface of the substrate, 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.

[0016] When the placement state is determined by the determination unit to be the first state (good), the control unit causes the relative position changing unit to change the distance between the cover and the stage to the second distance, and then causes the plasma generation unit to generate plasma. Using the generated plasma, plasma processing is performed. On the other hand, when the placement state is determined by the determination unit to be the second state (bad), the control unit does not change the distance between the transfer carrier and the cover to the second distance, and causes the transfer carrier to be placed on the stage again with the distance between the cover and the stage being greater than the second distance. In this case, since the placement process is retried with the transfer carrier and the cover sufficiently separated, it is possible to avoid the occurrence of an error due to the transfer carrier contacting the cover during the retry process.

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0018] First, an embodiment of the transfer 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 transfer carrier 10 holding the same, and FIG. 1(b) is a cross-sectional view of the substrate 1 and the transfer carrier 10 taken along line B-B shown in FIG. 1(a). As shown in FIG. 1(a), the transfer 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 transfer 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.

[0019] (Substrate) The substrate 1 is an object to be subjected to plasma processing. The substrate 1 is manufactured, for example, by forming a circuit layer such as a semiconductor circuit, an electronic component element, or MEMS on one surface of the 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.

[0020] The size of the substrate 1 is not particularly limited. For example, it is about 50 mm to 300 mm in maximum diameter. 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). Thus, the outer peripheral portion of the holding sheet 3 is fixed to a substantially flat frame 2, and the substrate 1 is adhered to this holding sheet 3. This makes it easy to handle the substrate 1, such as conveyance. The shape of the substrate 1 is also not particularly limited. For example, it can 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).

[0021] The material of the main body of the substrate is also not particularly limited. For example, it includes 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.

[0022] A mask is formed in a desired shape on the surface of the substrate 1 that is not adhered to the holding sheet 3 (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 the 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. Further, 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.

[0023] (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 conveyed while holding the holding sheet 3 and the substrate 1.

[0024] The shape of the opening of the frame 2 is not particularly limited, and for example, it may be circular, rectangular, or polygonal such as hexagonal. The frame 2 may be provided with notches 2a or 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 near one surface of the holding sheet 3 is adhered.

[0025] (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 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. Further, the substrate 1 is adhered to the portion of the adhesive surface 3a exposed from the opening of the frame 2.

[0026] The adhesive surface 3a preferably consists of an adhesive component whose adhesive force decreases upon irradiation with ultraviolet (UV) light. This is because by performing UV irradiation after dicing, the individual 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 base material to a thickness of 5 - 20 μm.

[0027] The material of the film - shaped base material is not particularly limited, and examples include thermoplastic resins such as polyolefins such as polyethylene and polypropylene, and polyesters such as polyethylene terephthalate. Various additives such as rubber components (e.g., ethylene - propylene rubber (EPM), ethylene - propylene - diene rubber (EPDM), etc.) for adding stretchability, plasticizers, softeners, antioxidants, and conductive materials may be blended in the base material. Further, the above - mentioned thermoplastic resin may have a functional group showing a photopolymerization reaction such as an acrylic group. The thickness of the base material 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.

[0028] (Plasma Treatment Apparatus) Next, while referring to FIG. 2, the basic structure of the plasma processing 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 processing apparatus 100.

[0029] 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.

[0030] The stage 111 and the cover 124 are disposed in a 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. 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 source 110A. The stage 111 is disposed on the bottom side in the vacuum chamber 103.

[0031] 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 connected to the gas inlet 103a by piping, respectively. Further, an exhaust port 103b is provided in the vacuum chamber 103, and a decompression mechanism 114 including a vacuum pump for exhausting and decompressing the gas in the vacuum chamber 103 is connected to the exhaust port 103b.

[0032] 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 through the window 130, it is possible to visually recognize the state in which the transfer carrier 10 is placed on the stage 111.

[0033] 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 transfer carrier 10 (for example, the region including the inner peripheral side wall of the frame 2) through the window 130 and acquires imaging data. By performing image analysis on the imaging data obtained by the imaging unit 131, it is possible to determine whether the placement state of the transfer 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 the control unit described later.

[0034] Each 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.

[0035] 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 arranged. 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 the stage 111 and fixed. 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 it is not limited thereto. The fixing of the holding sheet 3 to the stage 111 may be performed by a clamp (not shown).

[0036] The metal layer 116 is composed of, for example, aluminum or the like having an anodized coating formed on the surface. A refrigerant flow path 127 is formed in 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. Thereby, it is suppressed that the substrate 1 and the holding sheet 3 are damaged by being heated during the plasma treatment. The refrigerant in the refrigerant flow path 127 is circulated by a refrigerant circulation device 125.

[0037] A plurality of support portions 122 penetrating the stage 111 are arranged near the outer periphery of the stage 111. 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 not higher than that of the stage 111, the transfer carrier 10 is mounted at a predetermined position on the stage 111.

[0038] 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 lifting and lowering the cover 124 by the lifting mechanism 123B can be performed independently of the lifting mechanism 123A.

[0039] The lifting rods 121 and the lifting mechanism 123B constitute a relative position changing unit, which changes the relative distance between the cover 124 and the stage 111 between a first distance and a second distance smaller than the first distance. However, the method of changing the distance by the relative position changing unit is not limited to the method using the lifting rods 121. When the placement state of the transfer carrier 10 on the stage 111 is determined in a state where the distance between the cover 124 and the stage 111 is the first distance d1, and as a result, when the placement state is determined to be 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.

[0040] The dielectric member 108, the antenna 109, the first high-frequency power supply 110A, the second high-frequency power supply 110B, the process gas source 112, the pressure reducing mechanism 114, and the high-frequency electrode unit 120 constitute a plasma generation unit.

[0041] The control device 128 controls the operations of the components constituting the plasma processing apparatus 100, including the first high-frequency power supply 110A, the second high-frequency power supply 110B, the process gas source 112, the ashing gas source 113, the pressure reducing mechanism 114, the refrigerant circulation device 125, the lifting mechanism 123A, the lifting 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.

[0042] (Plasma processing method) Next, with reference to FIGS. 3 and 4, the basic steps of the plasma processing method according to the present embodiment will be described. FIG. 3 is a flowchart showing some steps of the plasma processing method.

[0043] FIGS. 4A to 4F are conceptual diagrams showing the positional relationship between the cover and the stage in each step of the plasma processing method. In FIGS. 4A to 4F, for ease of understanding of the invention, descriptions of the outer peripheral portion 118, the outer peripheral ring 129, and the gas introduction path are omitted.

[0044] A plasma processing method according to an embodiment of the present invention includes a substrate held by a transfer carrier including a frame and a holding sheet, a chamber, a plasma generation unit that generates plasma in the chamber, a stage provided in the chamber on which the transfer carrier is placed, and a cover that covers at least a part of the transfer carrier in a state where the transfer carrier is placed on the stage. The method includes a placement step of placing the transfer carrier on the stage of the plasma processing apparatus, and a determination step of determining the placement state of the transfer carrier in a state where the distance between the cover and the stage is a first distance. When it is determined in the determination step that the placement state is a first state (good), the distance between the cover and the stage is changed to a second distance smaller than the first distance, and then plasma is generated in the chamber, and the generated plasma is irradiated onto the substrate to perform plasma processing.

[0045] (1) Preparation step First, a transfer carrier 10 is prepared. The transfer 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 adhered to the adhesive surface 3a of the holding sheet 3, thereby holding the substrate 1 by the transfer carrier 10.

[0046] (2) Loading step Next, the transfer carrier 10 holding the substrate 1 is loaded into the vacuum chamber 103.

[0047] Figure 4A shows the positional relationship between the cover 124 and the stage 111 before the transfer carrier is carried in. As shown in Figure 4A, the elevating rod 121 and the support portion 122 are in the lowered positions.

[0048] Drive the elevating rod 121 and the support portion 122 to raise the cover 124 to a predetermined position within the vacuum chamber 103 and make the support portion 122 wait in the raised state. Figure 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.

[0049] 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 portion 122. The transfer carrier 10 is placed on the upper end surface of the support portion 122 such that the surface holding the substrate 1 of the holding sheet 3 faces upward. Figure 4C shows the positional relationship between the cover 124 and the stage 111 at this time.

[0050] (3) Placement step When the transfer carrier 10 is delivered to the support portion 122, retract the transfer arm 221, close the shutter, and make the vacuum chamber 103 in a sealed state. Then, lower the support portion 122. By lowering the upper end surface of the support portion 122 to a level below that of the stage 111, the transfer carrier 10 is placed on the stage 111. Figure 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.

[0051] Subsequently, the transfer carrier 10 placed on the stage 111 is fixed 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.

[0052] The ESC electrode 119 is roughly classified into two types: a single-pole type and a bipolar type. The single-pole type ESC electrode 119 includes at least one electrode. When two or more electrodes are included in the single-pole type ESC electrode 119, voltages of the same polarity are applied to all of them. The electrostatic adsorption mechanism provided with the single-pole type 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 order to charge the holding sheet 3, plasma may be generated in the vacuum chamber 103 and the generated plasma may be exposed to the holding sheet 3.

[0053] On the other hand, the bipolar type 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 type 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.

[0054] As the adsorption mechanism of the electrostatic adsorption mechanism equipped with the bipolar ESC electrode 119, there are cases of using Coulomb force and cases of using Johnson-Lambeck force. 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 with 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 transport carrier 10 can be adsorbed to the stage 111. Note that in the case of the bipolar type, different from the case of the unipolar type, it is not necessary to charge the holding sheet 3 in order to adsorb it.

[0055] The bipolar ESC electrode can also function as a unipolar type by 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.

[0056] When the ESC electrode 119 is bipolar, after the transport carrier 10 is transferred to the support portion 122, a voltage is applied from the DC power supply 126 to the ESC electrode 119. Thereby, 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 (after contact with) the holding sheet 3 is placed on the stage 111.

[0057] (4) Judgment step After the placement step, a judgment step for judging the placement state of the transport carrier is performed. Here, through the window 130, the placement state of the transport carrier 10 in the vacuum chamber 103 is photographed using the imaging unit 131, and the imaging data is subjected to image analysis. 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 judged.

[0058] For example, as shown in FIG. 4D, the imaging unit 131 is disposed at a position lateral to the transfer carrier 10 while being placed on the stage 111, and images the transfer carrier 10 at an angle slightly inclined from the placement surface of the transfer carrier (the main surface of the substrate 1). In particular, the imaging unit 131 images a region including the inner peripheral side wall of the frame 2 of the transfer carrier 10. 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.

[0059] When there is no lifting from the stage 111 in the substrate or the holding sheet and the placement state of the transfer carrier is good, the imaging data includes information on the inner peripheral side wall of the frame 2. However, for example, as shown in FIG. 4E, when the holding sheet is lifted from the stage 111 in a partial region, at least a part of the inner peripheral side wall of the frame is hidden by the lifted portion and does not appear in the imaging data. Therefore, by obtaining a 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 corresponding to the inner peripheral side wall of the frame in the imaging data is obtained, and if the area is equal to or greater than a predetermined value, the placement state is determined to be in the first state (good), and if it is less than the predetermined value, the placement state is determined to be in the second state (bad).

[0060] However, the method for determining the placement state of the transfer carrier is not limited to the method using the imaging unit 131 described above. For example, a method of providing a determination gas hole on the surface of the stage 111 facing the holding sheet 3, or a method of providing a displacement sensor or a temperature sensor may be used to determine whether the placement state of the transfer carrier is good or bad.

[0061] In the method of providing the determination gas holes, based on the time change of the gas pressure when introducing the determination gas through the determination gas holes, it is possible to determine whether the placement state of the transfer carrier is good or not. When the holding sheet 3 is lifted from the stage 111, a gap is formed between the holding sheet 3 and the stage 111. On the other hand, when the placement state of the transfer carrier is good, the holding sheet 3 is in close contact with the stage 111, and the determination gas holes are blocked by the holding sheet 3. Therefore, for example, when introducing the determination gas from the determination gas holes at a constant flow rate, if there is a gap between the holding sheet 3 and the stage 111, it takes time for the pressure to reach a predetermined value. Therefore, by measuring the time until the pressure reaches the predetermined value (or the gas pressure after a predetermined period has elapsed since the introduction of the determination gas), the placement state of the transfer carrier can be determined.

[0062] When using a displacement sensor, the displacement sensor moves above the stage 111 while being attached to the transfer arm, and measures the height of the substrate in the state where the transfer carrier is placed on the stage. The displacement sensor is not particularly limited, but a non-contact type is preferable. Examples of non-contact displacement sensors include optical (laser type), eddy current type, and ultrasonic type. When using a temperature sensor, the stage is cooled to a predetermined temperature (for example, -10°C or lower), and the temperature of the surface of the substrate 1 placed on the stage is measured. When the placement state of the transfer carrier is in the first state (good), the surface temperature of the substrate 1 is uniformly low, but when there is a portion where the holding sheet 3 has lifted from the stage 111 (second state), the temperature of that portion becomes high. The temperature sensor is not particularly limited, but a non-contact type is preferable. Examples of non-contact temperature sensors include radiation thermometers that measure infrared radiation energy. The radiation thermometer is installed outside the vacuum chamber 103 so as to face the viewing window provided above the vacuum chamber 103, for example.

[0063] When it is determined that the placement state of the transfer carrier 10 on the stage 111 is in 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 in the second state (bad), the transfer carrier 10 is unloaded from 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, while raising or lowering the support portion 122, the support portion 122 may be slightly raised and lowered. Thereby, the wrinkles of the holding sheet 3 are eliminated, and the lifting of the holding sheet is more easily eliminated.

[0064] (5) Plasma processing step In the determination step, when it is determined that the above-described 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 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 frame 2 and the portion of the holding sheet 3 that does not hold the substrate 1 are 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.

[0065] The cover 124 is, for example, donut-shaped with a substantially circular outer contour, having 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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 the ashing gas source 113 into the vacuum chamber 103. On the other hand, evacuation is performed by the pressure reducing 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.

[0072] (6) Unloading process When the ashing is completed, the gas in the vacuum chamber 103 is exhausted, 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

[0073] The plasma processing method of the present invention is useful when performing plasma processing using a plasma processing apparatus provided with a cover above the stage.

Explanation of symbols

[0074] 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, 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, comprising: a chamber; a plasma generation unit that generates plasma in the chamber; a stage provided in the chamber on which the transport carrier is placed; a cover that covers at least a part of the transport carrier placed on the stage; a relative position changing unit that can change the relative distance between the cover and the stage to a first distance and a second distance smaller than the first distance; a determination unit that determines the placement state of the transport carrier; a control unit that controls the plasma generation unit and the relative position changing unit, wherein the determination unit determines the placement state in a state where the distance between the cover and the stage is the first distance, and the plasma processing is performed in a state where the distance between the cover and the stage is the second distance. A plasma processing apparatus.

2. further comprising an imaging unit that images the transport carrier placed on the stage, wherein the determination unit determines the placement state based on imaging data imaged by the imaging unit in a state where the distance between the cover and the stage is the first distance. The plasma processing apparatus according to claim 1.

3. The determination unit determines the placement state based on the state of the inner peripheral side wall of the frame in the imaging data. The plasma processing apparatus according to claim 2.

4. When the determination unit determines that the placement state is the first state, the control unit causes the relative position changing unit to change the distance between the cover and the stage to the second distance, and then causes the plasma generation unit to generate the plasma. The plasma processing apparatus according to any one of claims 1 to 3.

5. When the determination unit determines that the placement state is the second state, the control unit causes the transport carrier to be placed on the stage again in a state where the distance between the cover and the stage is greater than the second distance. The plasma processing apparatus according to any one of claims 1 to 4.

6. Placing a substrate held by a transport 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, a stage provided in the chamber on which the transport carrier is placed, and a cover that covers at least a part of the transport carrier in a state where the transport carrier is placed on the stage; A determination step of determining the placement state of the transport carrier in a state where the distance between the cover and the stage is a first distance. When it is determined in the determination step that the placement state is a first state, A plasma processing method in which the distance between the cover and the stage is changed to a second distance smaller than the first distance, then plasma is generated in the chamber, and the generated plasma is irradiated onto the substrate to perform plasma processing.

7. The determination step includes an imaging step of imaging the transport carrier placed on the stage in a state where the distance between the cover and the stage is the first distance. The plasma processing method according to claim 6, wherein the placement state is determined based on imaging data imaged in the imaging step.

8. The plasma processing method according to claim 7, wherein in the determination step, the placement state is determined based on the state of the inner peripheral side wall of the frame in the imaging data.

Images