CN113948360A

CN113948360A - Plasma processing apparatus

Info

Publication number: CN113948360A
Application number: CN202110729723.5A
Authority: CN
Inventors: 渡边大辅; 目黑佑一
Original assignee: Shibaura Machine Co Ltd
Current assignee: Shibaura Machine Co Ltd
Priority date: 2020-07-15
Filing date: 2021-06-29
Publication date: 2022-01-18
Also published as: TWI794864B; TW202218098A

Abstract

The plasma processing apparatus according to the present invention processes a substrate, the substrate including: a base; a plurality of devices provided on one surface of the base; an organic film provided on one surface of the base and covering the plurality of devices; and a resist mask provided on the other surface of the base. The plasma processing apparatus includes an electrostatic chuck placed on a side of the substrate on which the organic film is formed. The electrostatic chuck has: a dielectric having a plurality of grooves opened on a surface thereof; an electrode provided inside the dielectric; a thin film provided on the surface of the dielectric, covering the openings of the plurality of grooves, and containing a fluororesin; and a joint portion provided between the film and the dielectric. When a dimension of the dielectric in a direction parallel to the surface is D1(mm) and a dimension of the film in a direction parallel to the surface is D2(mm), the following formula D2(mm) < D1(mm) is satisfied.

Description

Plasma processing apparatus

Technical Field

Embodiments of the present invention relate to a plasma processing apparatus.

Background

There is a substrate including a plate-like susceptor such as a wafer, a plurality of devices provided on one surface (hereinafter, referred to as a device surface) of the susceptor, and a resist mask formed on the other surface (hereinafter, referred to as a back surface) of the susceptor. For example, a resist mask is provided to implant ions into a predetermined region of the back surface of the susceptor.

In such a substrate, after ion implantation, a resist mask formed on the back surface side of the substrate is removed by plasma treatment or the like. In plasma processing, a substrate is placed on an electrostatic chuck. At this time, the back surface side of the substrate on which the resist mask to be removed is formed is directed to the plasma processing space, and the device surface side of the substrate is placed on the electrostatic chuck.

However, a plurality of devices are provided on the device surface side of the substrate. Therefore, in order to protect a plurality of devices, a technique of attaching a glass substrate to the device surface side of the substrate has been proposed. However, if a glass substrate is attached, the substrate is difficult to be adsorbed on the electrostatic chuck. Therefore, a gap is generated between the electrostatic chuck and the substrate, and cooling of the substrate by the electrostatic chuck is prevented. As a result, the adhesive layer to which the glass substrate is attached is easily modified by heat generated during the plasma treatment. If the adhesive layer is altered, it may be difficult to peel off the glass substrate, or a part of the adhesive layer may remain on the device surface side of the substrate when the glass substrate is peeled off.

In addition, a technique of attaching a thin plate to the device surface side of the substrate has been proposed. Depending on the type of sheet, the substrate is more likely to adhere to the electrostatic chuck than when it is a glass substrate. However, a gap is still likely to be formed between the electrostatic chuck and the substrate. Therefore, similarly to the case of a glass substrate, it may be difficult to peel the thin plate, or a part of the adhesive layer may remain on the device surface side of the substrate when the thin plate is peeled.

Further, if a glass substrate or a thin plate is to be bonded to a substrate, a device for bonding these to the substrate and a device for removing these from the substrate are required. As a result, the manufacturing cost is increased.

Accordingly, a method for protecting a device instead of a glass substrate or a thin plate is required. The present inventors have studied a method of providing an organic film covering a plurality of devices on the device surface side of a substrate instead of a glass substrate or a thin plate. Since the thickness of the organic film can be reduced, the substrate is easily adsorbed to the electrostatic chuck. Therefore, the organic film is easily cooled by the electrostatic chuck. Thus, the temperature rise of the organic film can be suppressed. The organic film may be formed by an existing technique such as spin coating, and the organic film may be removed by an existing technique such as plasma treatment or wet treatment. Therefore, the formation and removal of the organic film can be handled by an existing apparatus.

However, it was found that when the substrate in a state of being supported by the electrostatic chuck is subjected to plasma processing and then separated from the electrostatic chuck, a part of the organic film remains on the surface of the electrostatic chuck. If a material such as an organic film is adhered to the surface of the electrostatic chuck, a gap is likely to be formed between the electrostatic chuck and the substrate. Therefore, cooling of the substrate by the electrostatic chuck is suppressed, or the attraction force of the electrostatic chuck becomes weak.

Here, a technique of coating a modified fluororesin on the surface of an electrostatic chuck has been proposed (for example, see patent document 1).

If a layer containing a modified fluororesin is formed on the surface of the electrostatic chuck, the adhesion of the organic film material to the surface of the electrostatic chuck can be suppressed. However, in the case of an electrostatic chuck for cooling a substrate, it is necessary to provide a groove through which a cooling gas flows on the surface of the electrostatic chuck. If the coating of the modified fluororesin is applied to the electrostatic chuck having the grooves on the surface, the grooves are clogged with the modified fluororesin. As a result, it is difficult to perform cooling using the cooling gas.

In this case, an electrostatic chuck may be considered in which a fluororesin film having an adhesive on only one surface is bonded to the surface. However, even at this time, the adhesive or the like of the bonding film may be decomposed by the etchant. That is, the vicinity of the peripheral end of the film may be peeled off from the surface of the electrostatic chuck.

Accordingly, there is a demand for development of a plasma processing apparatus capable of suppressing peeling from the surface of an electrostatic chuck in the vicinity of the peripheral end of a thin film provided on the electrostatic chuck.

Patent document

Patent document 1: japanese laid-open patent application No. 2008-91353

Disclosure of Invention

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a plasma processing apparatus capable of suppressing peeling from the surface of an electrostatic chuck in the vicinity of the peripheral end of a thin film provided on the electrostatic chuck.

A plasma processing apparatus according to an embodiment processes a substrate, the substrate including: a base; a plurality of devices provided on one surface of the base; an organic film provided on one surface of the base and covering the plurality of devices; and a resist mask provided on the other surface of the base. The plasma processing apparatus includes an electrostatic chuck placed on a side of the substrate on which the organic film is formed. The electrostatic chuck has: a dielectric having a plurality of grooves opened on a surface thereof; an electrode provided inside the dielectric; a thin film provided on the surface of the dielectric, covering the openings of the plurality of grooves, and containing a fluororesin; and a joint portion provided between the film and the dielectric. When a dimension of the dielectric in a direction parallel to the surface is D1(mm) and a dimension of the film in a direction parallel to the surface is D2(mm), the following formula D2(mm) < D1(mm) is satisfied.

According to an embodiment of the present invention, there is provided a plasma processing apparatus capable of suppressing peeling from a surface of an electrostatic chuck in the vicinity of a peripheral end of a thin film provided on the electrostatic chuck.

Drawings

Fig. 1 is a schematic cross-sectional view of a substrate.

Fig. 2 is a schematic cross-sectional view illustrating the plasma processing apparatus according to the present embodiment.

Fig. 3 is a schematic sectional view illustrating the structure of the electrostatic chuck.

Fig. 4 is a schematic top view of an electrostatic chuck.

Fig. 5 is a schematic cross-sectional view illustrating an electrostatic chuck according to a comparative example.

Fig. 6 is a schematic cross-sectional view illustrating the operation of the thin film.

Fig. 7 is a diagram illustrating the effect of the thin film.

Description of the symbols

1-a plasma processing apparatus; 2-a chamber; 3-a power supply unit; 4-a power supply unit; 5-a decompression part; 6-gas supply; 7-a placement section; 71-an electrostatic chuck; 71 a-a dielectric; 71a 1-groove; 71 b-an electrode; 71 c-a film; 71c 1-joint; 75-cooling gas supply; 100-a substrate; 101-a base; 102-a device; 103-resist mask; 104-organic film.

Detailed Description

Hereinafter, embodiments will be described by way of example with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.

Substrate 100

First, a substrate 100 to be processed by the plasma processing apparatus 1 according to the present embodiment is exemplified.

Fig. 1 is a schematic cross-sectional view of a substrate 100.

As shown in fig. 1, a base 101, a device 102, a resist mask 103, and an organic film 104 may be disposed on a substrate 100.

The base 101 can be formed into a plate-like body. The susceptor 101 may be a semiconductor substrate such as a wafer. The base 101 has a back surface 101a and a device surface 101 b. The back surface 101a of the base 101 is provided with a recess 101a 1. For example, the concave portion 101a1 can be formed by polishing the back surface 101a of the base 101. The recess 101a1 is not necessarily required. However, if the recess 101a1 is provided, the thickness of the region of the base 101 where the plurality of devices 102 are formed can be reduced. Therefore, ions and the like are easily implanted from the rear surface 101a side of the base 101 into the region where the device 102 is formed.

The plurality of devices 102 are provided on the device surface 101b of the base 101. The type, number, configuration, etc. of the devices 102 are not expressly limited. The device 102 may be, for example, a power transistor or the like having a back electrode. Since the plurality of devices 102 can be formed by a known semiconductor manufacturing flow, detailed description of manufacturing and the like of the plurality of devices 102 is omitted.

The resist mask 103 can be provided on the bottom surface of the recess 101a 1. A resist mask 103 is provided to implant ions or the like into a predetermined region of the bottom surface of the recess 101a 1. For example, the resist mask 103 may be a so-called ion implantation resist mask or the like. Since the resist mask 103 can be formed by a known photolithography method, a detailed description of the manufacture of the resist mask 103 and the like is omitted.

The substrate 100 to be processed by the plasma processing apparatus 1 is the ion-implanted substrate 100. Therefore, a solidified layer formed by allowing ions to enter the resist mask 103 in the ion implantation step exists on the surface of the resist mask 103.

The organic film 104 is provided on the device surface 101b of the base 101 and covers the plurality of devices 102. An organic film 104 is provided to protect the plurality of devices 102. The thickness of the organic film 104 is not particularly limited. As long as the plurality of devices 102 are covered with the organic film 104. In particular, if the ease of removal and the reduction in removal time after use as a protective film are taken into consideration, the thickness of the organic film 104 is preferably as thin as possible.

However, if the thickness of the organic film 104 is too thin, the particles 200 may reach the device 102 when the particles 200 to be described later are pressed against the organic film 104 (see, for example, fig. 5 and 6). Generally, the thickness of the device 102 is about several hundred nm, and thus the thickness of the organic film 104 may be, for example, 1 μm or more. More preferably 3 μm to 10 μm. The organic film 104 may contain a resin such as a photoresist or polyimide. Since the organic film 104 can be formed by a known spin coating method or the like, a detailed description of manufacturing or the like is omitted. The thickness of the organic film 104 is a thickness t (see fig. 1) that can cover the thickest part of the device 102. For example, the thickness t may be confirmed by confirming the cross section of the substrate 100 by TEM or SEM.

Plasma processing apparatus 1

Next, the plasma processing apparatus 1 according to the present embodiment will be exemplified.

In addition, a dual-frequency plasma processing apparatus having an inductively coupled electrode in the upper portion and a capacitively coupled electrode in the lower portion is described as an example below. However, the method of generating plasma is not limited thereto. For example, the Plasma processing apparatus may be a Plasma processing apparatus using Inductively Coupled Plasma (ICP), a Plasma processing apparatus using Capacitively Coupled Plasma (CCP), or the like.

However, as described above, a solidified layer formed in the ion implantation step exists on the surface of the resist mask 103 to be removed. Therefore, it is preferable that the solidified layer which is difficult to chemically remove by radicals or the like is physically removed by ions. In this case, if the dual-frequency plasma processing apparatus is used, the energy of ions introduced into the substrate 100 can be controlled, and therefore, the solidified layer can be easily removed. Therefore, the plasma processing apparatus 1 is preferably a dual-frequency plasma processing apparatus.

Further, since a known technique can be applied to the general operation of the plasma processing apparatus 1, the flow conditions for removing the resist mask 103, and the like, detailed description thereof will be omitted.

Fig. 2 is a schematic cross-sectional view illustrating the plasma processing apparatus 1 according to the present embodiment.

As shown in fig. 2, the plasma processing apparatus 1 may be provided with a chamber 2, a power supply unit 3, a power supply unit 4, a pressure reducing unit 5, a gas supply unit 6, a placing unit 7, and a controller 8.

The controller 8 may include an arithmetic unit such as a cpu (central Processing unit) and a storage unit such as a memory. The controller 8 may be a computer, for example. The controller 8 controls the operations of the respective elements provided in the plasma processing apparatus 1 according to a control program stored in the storage unit. Since a known technique can be applied to a control program for controlling the operation of each element, detailed description thereof will be omitted.

The chamber 2 has an airtight structure that can maintain an atmosphere decompressed more than atmospheric pressure. The chamber 2 is, for example, substantially cylindrical in shape. The chamber 2 can be formed of a metal such as an aluminum alloy, for example. The chamber 2 may be grounded.

A hole 2a for loading and unloading the substrate 100 can be provided in a side surface of the chamber 2. In a portion of the Chamber 2 where the hole 2a is provided, a Load Lock Chamber (Load Lock Chamber)21 may be connected. A gate valve 22 can be provided to the load-lock vacuum chamber 21. When the plasma treatment is performed, the hole 2a is hermetically sealed by the gate valve 22. When the substrate 100 is carried in and out, the holes 2a communicate with the load lock chamber 21 through the gate valve 22.

On the top surface of the chamber 2, a window 23 is provided hermetically. The window 23 has a plate shape. The window 23 is permeable to electromagnetic fields. The window 23 can be formed of a material that is difficult to be damaged when plasma treatment is performed. The window 23 can be formed of a dielectric material such as quartz.

A shielding body 24 can be provided inside the chamber 2. Reaction products are generated when plasma processing is performed. The reaction product is deposited on the inner wall of the chamber 2, and if the deposited reaction product is peeled off, it becomes a contaminant such as a particle. In addition, if the deposition amount increases, the processing environment changes, the processing rate changes, and unevenness occurs in the quality of the product. Therefore, the cleaning is performed periodically or in accordance with the amount of the reaction product deposited. In this case, although the inner wall of the chamber 2 may be cleaned, it takes much labor, time, and cost.

Then, a shielding body 24 is provided inside the chamber 2. The shielding body 24 has a cylindrical shape and may be provided to cover, for example, the upper surface of the placement section 7 and a portion other than the surface of the window 23. The shielding body 24 is formed of, for example, an aluminum alloy or the like, and the surface thereof may be subjected to alumite treatment, ceramic sputtering treatment (aluminum oxide, yttrium, or the like), or the like. If the shielding body 24 is provided, only the shielding body 24 may be replaced at the time of cleaning. Thus, the labor required for cleaning can be significantly reduced.

The power supply unit 3 generates plasma P in the inner space of the chamber 2.

The power supply unit 3 includes, for example, an antenna 31, a matching unit 32, and a power supply 33.

The antenna 31 may be disposed outside the chamber 2 and on the window 23. The antenna 31 is electrically connected to a power supply 33 via a matching unit 32. The antenna 31 may have, for example, a plurality of coils and a plurality of capacitors that generate an electromagnetic field.

The matching unit 32 may include: impedance on the power supply 33 side; and a matching circuit for matching the impedance of the plasma P side.

The power supply 33 may be a high frequency power supply. The power supply 33 applies high-frequency power having a frequency of, for example, about 100KHz to 100MHz to the antenna 31. At this time, the power supply 33 applies high-frequency power having a frequency (for example, 13.56MHz) suitable for generating the plasma P to the antenna 31. In addition, the power supply 33 may also change the frequency of the output high-frequency power.

The power supply unit 4 is provided for so-called bias control. That is, the power supply unit 4 is provided to control the energy of ions introduced into the substrate 100. As described above, the cured layer is formed on the surface of the resist mask 103. The cured layer has high hardness and is difficult to chemically remove by radicals or the like. The plasma processing apparatus 1 according to the present embodiment is provided with a power supply unit 4. Accordingly, by controlling the energy of ions introduced into the substrate 100, the sputtering effect due to the ions is easily generated. Therefore, the solidified layer is easily physically removed.

The power supply unit 4 includes, for example, a base 41, a matching unit 42, and a power supply 43.

The susceptor 41 is provided at the bottom of the chamber 2 via an insulating member 41 a. The base 41 is electrically connected to a power supply 43 via a matching unit 42. In addition, an electrostatic chuck 71 may be provided on the base 41. The susceptor 41 serves as an electrode to which high-frequency power is applied from the power supply 43, and also serves as a support base for supporting the electrostatic chuck 71. In this case, the base 41 may have a flow path for flowing cooling water therein to cool the electrostatic chuck 71. The base 41 can be formed of a metal such as an aluminum alloy, for example.

Matching unit 42 is electrically connected between base 41 and power supply 43. Matching unit 42 may include a matching circuit or the like for matching the impedance on the power supply 43 side and the impedance on the plasma P side.

The power supply 43 may be a high frequency power supply. The power supply 43 applies high-frequency power having a frequency suitable for introducing ions (for example, 13.56MHz or less) to the susceptor 41.

The decompression section 5 decompresses the inside of the chamber 2 to a predetermined pressure. For example, when the resist mask 103 is removed, the pressure reducing unit 5 can reduce the pressure inside the chamber 2 to 100Pa or less.

The decompression section 5 includes, for example, an on-off valve 51, a pump 52, and a pressure controller 53.

The opening and closing valve 51 is connected to a hole 2b provided on the side surface of the chamber 2. The on-off valve 51 opens and closes a flow path between the chamber 2 and the pump 52. The opening and closing valve 51 may be a poppet valve, for example.

The Pump 52 may be, for example, a Turbo Molecular Pump (TMP) or the like.

A pressure controller 53 may be provided between the on-off valve 51 and the pump 52. The pressure controller 53 controls the internal pressure of the chamber 2 to a predetermined pressure based on an output of a vacuum gauge or the like, not shown, which detects the internal pressure of the chamber 2. The Pressure controller 53 may be, for example, an apc (auto Pressure controller).

The gas supply unit 6 supplies the gas G to the internal space of the chamber 2 through a plurality of nozzles 2c provided on the side surface of the chamber 2. For example, the plurality of nozzles 2c can be arranged at substantially equal intervals around the central axis of the chamber 2. Thus, the concentration of the gas G can be suppressed from being deviated in the region where the plasma P is generated.

The gas supply unit 6 includes, for example, a gas source 61, a gas controller 62, and an opening/closing valve 63.

The gas source 61 supplies gas G into the chamber 2 through the gas controller 62 and the on-off valve 63. The gas source 61 may be, for example, a high-pressure bottle or the like containing the gas G. The gas source 61 may be, for example, a plant pipe.

The gas G can be excited and activated by the plasma P to generate radicals that react with the resist mask 103 provided on the substrate 100. The gas G may be, for example, oxygen gas or a mixed gas of oxygen gas and helium gas.

A gas controller 62 can be provided between the gas source 61 and the chamber 2. The gas controller 62 controls at least one of the flow rate and the pressure of the gas G supplied from the gas source 61. The gas controller 62 may be, for example, an MFC (Mass Flow controller) or the like.

The open-close valve 63 can be provided between the gas controller 62 and the chamber 2. The on-off valve 63 controls the start and stop of the supply of the gas G. The on-off valve 63 may be, for example, a two-way solenoid valve. The gas controller 62 may also have a function of an opening/closing valve 63.

The mounting unit 7 includes, for example, an electrostatic chuck 71, an insulating ring 72, a mask ring 73, a power supply unit 74, and a cooling gas supply unit 75. The placing unit 7 may be provided with a lift pin 76 for transferring the substrate 100 between a not-shown conveying device and the electrostatic chuck 71 (see, for example, fig. 6).

The side of the substrate 100 on which the organic film 104 is formed is placed on the electrostatic chuck 71. The electrostatic chuck 71 generates an electrostatic force to attract the substrate 100. The electrostatic chuck 71 can use coulomb force or johnson rahbeck force. Hereinafter, a case where the electrostatic chuck 71 utilizes coulomb force will be described as an example.

In addition, when the resist mask 103 is removed, the electrostatic chuck 71 cools the substrate 100 to prevent the temperature of the substrate 100 from becoming excessively high. That is, the electrostatic chuck 71 has a function of sucking the substrate 100 and a function of cooling the substrate 100.

Fig. 3 is a schematic sectional view illustrating the structure of the electrostatic chuck 71.

Fig. 4 is a schematic plan view of the electrostatic chuck 71.

As shown in fig. 3, an electrostatic chuck 71 is provided on the base 41.

The electrostatic chuck 71 includes, for example, a dielectric 71a, an electrode 71b, and a thin film 71 c.

The dielectric 71a has a step shape in which the thickness of the central region is larger than the thickness of the peripheral region surrounding the central region. The peripheral edge region of the dielectric 71a can be attached to the base 41 by a fastening member such as a bolt. The dielectric 71a may be formed of a ceramic such as alumina.

As shown in fig. 3 and 4, a plurality of grooves 71a1 are provided on the surface of the dielectric 71 a. The plurality of grooves 71a1 open on the surface of the dielectric 71 a. At this time, the plurality of grooves 71a1 can be divided into a plurality of groups, and the grooves 71a1 included in 1 group can be communicated with each other. For example, as shown in fig. 4, the plurality of grooves 71a1 can be divided into 3 groups 71aa to 71 ac. Further, the grooves 71a1 included in the group 71aa can be communicated with each other, the grooves 71a1 included in the group 71ab can be communicated with each other, and the grooves 71a1 included in the group 71ac can be communicated with each other.

In addition, the dielectric 71a may be provided with a plurality of 1 st holes 71a2 connected to the plurality of grooves 71a 1. The plurality of 1 st holes 71a2 can be divided into: the air supply holes 71a2a for supplying a cooling gas G1 described later to the plurality of grooves 71a 1; and an exhaust hole 71a2b for exhausting the cooling gas G1 supplied to the grooves 71a 1. The cooling gas supply unit 75 described later can be connected to the gas supply hole 71a2 a. An exhaust pipe or the like, not shown, can be connected to the exhaust hole 71a2 b. For example, at least 1 air supply hole 71a2a and air discharge hole 71a2b can be connected to the groove 71a1 included in 1 group 71aa (71ab, 71 ac).

The cooling gas G1 supplied to the plurality of grooves 71a1 through the gas supply hole 71a2a flows through the plurality of grooves 71a1, and is then discharged to an exhaust pipe or the like, not shown, through the gas discharge hole 71a2 b. That is, the grooves 71a1 serve as flow paths for the cooling gas G1 supplied from the cooling gas supply unit 75.

Further, the dielectric 71a may be provided with a plurality of holes 71a3 (corresponding to an example of the 2 nd hole) penetrating in the thickness direction. The plurality of holes 71a3 may each have a lift pin 76 (see, e.g., fig. 6) disposed therein.

Further, a groove 71a1 connected to the hole 71a3, and an air supply hole 71a2a and an air discharge hole 71a2b connected to the groove 71a1 may be provided. Part of the cooling gas G1 supplied to the groove 71a1 through the gas supply hole 71a2a flows through the inside of the groove 71a1 and then diffuses in the hole 71a 3. Therefore, a portion of the cooling gas G1 directly contacts the portion of the organic film 104 opposite the hole 71a 3. Thus, the cooling efficiency can be improved.

The electrode 71b is plate-shaped and is provided inside the dielectric 71 a. The electrode 71b may be a unipolar type or a bipolar type. For example, in the case of a bipolar type, 2 electrodes 71b may be arranged in a row on the same plane. The electrode 71b can be formed of a metal such as tungsten or molybdenum, for example.

The thin film 71c is formed in a film shape and is provided on the surface of the dielectric 71 a. The film 71c covers the openings of the plurality of grooves 71a 1. The film 71c may contain a fluororesin, for example. Further, a joint portion 71c1 is provided between the film 71c and the dielectric 71 a. The joining portion 71c1 may be a layer formed by curing an adhesive, an adhesive tape, or the like.

At this time, if the joint 71c1 enters the groove 71a1, the flow of the cooling gas may be obstructed. If the joint portion 71c1 is an adhesive tape, it is easy to suppress the penetration of the joint portion 71c1 into the groove 71a 1. Further, the work of attaching the film 71c and the work of detaching the film 71c are facilitated.

Further, if the total of the thickness of the bonding portion 71c1 and the thickness of the thin film 71c is too large, the force of suction to the substrate 100 may be weakened or cooling of the substrate 100 may be suppressed. Therefore, the total of the thickness of the joining portion 71c1 and the thickness of the film 71c is preferably 100 μm or less.

In addition, if the irregularities on the surface of the thin film 71c are too large, the gap between the thin film 71c and the substrate 100 (organic film 104) becomes large. Therefore, the force of attraction to the substrate 100 becomes weak or cooling of the substrate 100 by the electrostatic chuck 71 is suppressed.

As described above, since the thickness of the joint portion 71c1 and the thickness of the film 71c are small, the irregularities on the surface of the dielectric 71a are transferred to the surface of the film 71 c. Therefore, the arithmetic mean roughness Ra of the surface of the dielectric 71a is preferably 0.3 μm or less. Thus, the unevenness on the surface of the film 71c can be reduced.

Fig. 5 is a schematic cross-sectional view illustrating an electrostatic chuck 171 according to a comparative example.

The electrostatic chuck 171 is provided with the dielectric 71a and the electrode 71b, but is not provided with the thin film 71 c. Therefore, the organic film 104 of the substrate 100 directly contacts the surface of the dielectric 71 a.

As described above, the dielectric 71a is formed of ceramic such as alumina. Therefore, when the substrate 100 is held by the electrostatic chuck 171 without the thin film 71c, the substrate 100 comes into contact with the dielectric 71a of the electrostatic chuck. Since the substrate 100 is in contact with the dielectric 71a of the electrostatic chuck 171, there is a possibility that fine particles including ceramics are generated. Further, the substrate 100 and the dielectric 71a expand due to the heat of the plasma. Since the substrate 100 and the dielectric 71a have different coefficients of expansion, there is a possibility that friction may occur when expansion occurs. Therefore, fine particles 200 made of ceramic or the like may adhere to the surface of the dielectric 71 a. If the substrate 100 is attracted to the electrostatic chuck 171 in a state where the particles 200 are attached to the surface of the dielectric 71a, the particles 200 present on the surface of the dielectric 71a enter the organic film 104 as shown in fig. 5.

In general, the groove 71a1 of the dielectric 71a is formed by cutting. Therefore, burrs may be formed in the groove 71a 1. Since the cooling gas G1 flows in the groove 71a1, the burr may be peeled off from the groove 71a1 during the plasma treatment to become the particle 200. The cooling gas supply unit 75 described later supplies the cooling gas G1 through a filter not shown. However, the particles 200 that have leaked through the filter or the particles 200 that have passed through the filter and existed between the paths to the groove 71a1 may be included in the cooling gas G1. Therefore, in the electrostatic chuck 171 without the thin film 71c, there is a possibility that the particles 200 existing inside the grooves 71a1 enter the inside of the organic film 104 due to the cooling gas G1.

In addition, the dielectric 71a may be provided with a hole 71a3 for providing the lift pin 76. When the cooling gas is supplied to the holes 71a3, there is a possibility that the particles 200 present on the inner wall of the holes 71a3 enter the inside of the organic film 104 due to the cooling gas.

At this time, if the particle diameter of the particles 200 is larger than the distance between the end of the device 102 and the surface of the organic film 104, the particles 200 entering the inside of the organic film 104 reach the device 102. Thus, the device 102 may be damaged.

Fig. 6 is a schematic cross-sectional view illustrating the operation of the film 71 c.

As described above, the thin film 71c is provided on the surface of the dielectric 71 a. Therefore, as shown in fig. 6, even if the particles 200 adhere to the surface of the dielectric 71a, the thin film 71c can prevent the particles 200 from entering the organic film 104.

In addition, as described above, the film 71c covers the openings of the plurality of grooves 71a 1. Therefore, the particles 200 present on the inner wall of the groove 71a1 can be prevented from entering the organic film 104 by the cooling gas.

Fig. 7 is a diagram illustrating the effect of the film 71 c.

In fig. 7, "a 1" and "a 2" indicate the number of particles 200 adhering to the surface of the organic film 104 in the electrostatic chuck 171 according to the comparative example. That is, the number of particles 200 adhering to the surface of the organic film 104 when the thin film 71c is not provided is shown. "A2" is the case where the particle diameter of the particle 200 is 5 μm or more. That is, "a 2" represents the number of particles 200 having a size that may cause the aforementioned damage to the device 102. "A1" means that the particle diameter of the particles 200 is 0.3 μm or more but less than 5 μm. That is, "a 1" represents the number of particles 200 of almost the entire size except for particles 200 of a size to the extent that damage may occur to the device 102.

"B1" indicates the number of particles 200 adhering to the surface of the organic film 104 in the electrostatic chuck 71 according to the present embodiment. That is, the number of particles 200 adhering to the surface of the organic film 104 when the thin film 71c is provided is shown. "B1" means that the particle diameter of the particles 200 is 0.3 μm or more but less than 5 μm. That is, "B1" represents the number of particles 200 of almost the entire size except for particles 200 of a size to the extent that damage may occur to the device 102.

As can be seen from fig. 7, if the openings of the plurality of grooves 71a1 are covered with the thin film 71c, the number of particles 200 of almost the entire size adhering to the surface of the organic film 104 can be reduced. That is, the particles 200 adhering to the organic film 104 can be suppressed. In addition, it is possible to prevent the particles 200 having a size such that the device 102 can be damaged from adhering to the surface of the organic film 104. That is, it is possible to prevent the generation of particles having a size of 5 μm or more that can damage the device 102.

In order to confirm that the present inventors formed the organic film 104 on the surface of the aluminum substrate, experiments were performed to determine whether indentations due to the particles 200 were generated on the surface of the substrate. The indentation means a flaw or a depression having a planar size of 5 μm × 5 μm or more.

In the case of the electrostatic chuck 171 (in the case where the film 71c is not provided), 67 impressions are generated.

In the case of the electrostatic chuck 71 (in the case where the film 71c is provided), no indentation is generated. This means that if the thin film 71c is provided on the surface of the electrostatic chuck 71, the device 102 can be prevented from being damaged.

On the other hand, it was found that if the substrate 100 is separated from the electrostatic chuck 71 after the plasma treatment is performed, a part of the organic film 104 of the substrate 100 remains on the surface of the electrostatic chuck 71 (on the thin film 71 c). The film 71c at this time is made of polyimide.

If a part of the organic film 104 adheres to the thin film 71c provided on the surface of the dielectric 71a, adhesion between the electrostatic chuck 71 and the substrate 100 is inhibited, and cooling of the substrate 100 by the electrostatic chuck 71 is suppressed or the suction force of the electrostatic chuck 71 is weakened.

The present inventors considered that this is because the organic film 104 does not have an adhesive layer unlike a glass substrate or a thin plate. That is, the present inventors considered that this is because the adhesion force between the organic film 104 and the device 102 and the device surface 101b is weaker than the adhesion force between the organic film 104 and the surface of the thin film 71 c.

In the case of the present embodiment, since the thin film 71c contains a fluororesin, the material of the organic film 104 is less likely to adhere. In addition, when the resist mask 103 is removed, the thin film 71c is less likely to be decomposed or altered by plasma.

Further, the etchant may enter from a gap between the mask ring 73 and the substrate 100, which will be described later. In this case, as shown in fig. 3, when the dimension of the dielectric 71a parallel to the surface is D1(mm) and the dimension of the thin film 71c parallel to the surface is D2(mm), it is preferable that "D2 (mm) < D1 (mm)". Thus, the peripheral end surface of the joint portion 71c1 is provided closer to the center of the dielectric 71a than the peripheral end surface of the dielectric 71 a. Therefore, the etchant entering from the gap between the mask ring 73 and the substrate 100 hardly reaches the vicinity of the peripheral end of the joint portion 71c 1. Therefore, the vicinity of the peripheral end of the bonding portion 71c1 is prevented from being decomposed and the vicinity of the peripheral end of the film 71c is prevented from being peeled off from the surface of the dielectric 71 a. According to the knowledge obtained by the present inventors, if the distance between the peripheral end face of the dielectric 71a and the peripheral end face of the thin film 71c is L (mm), it is preferable that "0.5 mm. ltoreq. L.ltoreq.5 mm". Thus, the peeling of the vicinity of the peripheral end of the film 71c from the surface of the dielectric 71a can be effectively suppressed. The etchant is an active species such as ions and radicals generated from the gas G excited and activated by the plasma P.

Here, the organic film 104 is the same as the resist mask 103 to be removed. Therefore, when the resist mask 103 is removed, the exposed portion of the organic film 104 (for example, the peripheral end face of the organic film 104) may be decomposed by the etchant that intrudes from the gap between the mask ring 73 and the substrate 100. If the decomposed material of the organic film 104 adheres to the surface of the thin film 71c, the material of the organic film 104 adhering may be changed in quality and hardened by heat or the like. Further, as the number of processed substrates 100 increases, the amount of adhesion may increase with time. If there are adhering matter having high hardness or adhering matter having large size on the surface of the electrostatic chuck 71 (film 71c), the adhering matter can interfere with the substrate 100 even when the substrate 100 is placed on the electrostatic chuck 71. If the adhering matter interferes with the substrate 100, the substrate 100 may be damaged, the force of suction to the substrate 100 may be weakened, or unevenness may occur in the in-plane distribution of the temperature of the substrate 100.

In the electrostatic chuck 71 according to the present embodiment, when the dimension of the organic film 104 in the direction parallel to the surface is D3, "D2 (mm) < D3 (mm)". Since the thin film 71c is covered with the organic film 104 when the substrate 100 is adsorbed in this way, even if the vicinity of the peripheral end of the organic film 104 is decomposed, the adhesion of the material of the organic film 104 to the surface of the thin film 71c can be suppressed. Therefore, it is possible to suppress the occurrence of damage to the substrate 100, weakening of the force of adsorption to the substrate 100, or unevenness in the in-plane distribution of the temperature of the substrate 100 due to the material of the organic film 104 adhering thereto.

As described above, the particles 200 including ceramic and the like are generated due to the contact between the electrostatic chuck and the substrate 100. However, as described above, the surface of the dielectric 71a is polished to reduce the unevenness of the surface of the dielectric 71 a. Therefore, it is considered that the particles 200 including ceramics and the like are generated also when the dielectric 71a is formed. It is considered that the particles 200 including ceramics or the like generated when the dielectric 71a is formed adhere to the surface of the dielectric 71 a. The particles 200 including ceramics and the like adhering to the formation of the dielectric 71a cannot be completely removed by ordinary washing, and a part thereof continues to adhere to the dielectric 71 a.

The present inventors dealt with the problem that particles 200 made of ceramic or the like adhere to the dielectric 71a by covering the surface of the dielectric 71a and the groove 71a1 with a film 71 c.

At this time, if the film 71c is made to be "D2 (mm) < D3 (mm)" in a state where the film does not cover the vicinity of the peripheral end of the dielectric 71a, there is a possibility that the particles 200 including ceramics or the like adhere to the vicinity of the peripheral end of the organic film 104.

In this embodiment, the vicinity of the peripheral end of the organic film 104 does not contact the electrostatic chuck 71. Therefore, even if the particles 200 of 5 μm or more are attached to the vicinity of the peripheral end of the organic film 104, it is considered that the particles 200 of 5 μm or more do not enter the inside of the organic film 104. However, during the transfer of the substrate 100 after the plasma treatment and when the treatment is performed on the rear surface 101a of the substrate 100 in the next step, the organic film 104 may contact an electrostatic chuck of a transfer arm or another device. That is, if particles 200 of 5 μm or more, which can damage the device 102, adhere to the vicinity of the peripheral end of the organic film 104, there is a possibility that damage may occur to the device. However, as shown in fig. 7, in the present embodiment, the particles 200 of 5 μm or more, which can damage the device 102, are prevented from adhering to the organic film 104.

Even if the thin film 71c does not cover the vicinity of the peripheral end of the dielectric 71a, the particles 200 having a size of 5 μm or more, which may be damaged in the device 102, do not adhere to the organic film 104, and the mechanism thereof is not necessarily clear. However, the following is considered.

By attaching the thin film 71c to the surface of the dielectric 71a, a distance is generated between the particles 200 made of ceramic or the like attached to the vicinity of the peripheral end of the dielectric 71a and the organic film 104 of the substrate 100. Therefore, it is considered that the particles 200 can be suppressed from adhering to the organic film 104.

Next, other elements provided in the placing section 7 will be described with reference to fig. 2.

As shown in fig. 2, the insulating ring 72 is cylindrical and is disposed at the bottom of the chamber 2. The insulating ring 72 covers the side surface of the base 41. The insulating ring 72 can be formed of a dielectric material such as quartz.

The mask ring 73 has a cylindrical shape and is provided in a peripheral edge region of the dielectric 71a of the electrostatic chuck 71. The mask ring 73 encloses a central region of the electrostatic chuck 71. By disposing the mask ring 73 in this manner, the vicinity of the peripheral edge of the dielectric 71a can be prevented from being exposed to the etchant. Therefore, the dielectric 71a is provided in the peripheral edge region, and the aforementioned connecting member can be prevented from being damaged by the etchant.

The mask ring 73 can be formed of a dielectric material such as quartz, for example.

In addition, if the mask ring 73 is provided, the etchant can be suppressed from reaching the peripheral end face of the organic film 104 when the resist mask 103 is removed. Therefore, the adhesion of the material of the organic film 104 to the surface of the electrostatic chuck 71, which is generated by the decomposition of the peripheral end surface of the organic film 104, can be suppressed.

The power supply unit 74 includes, for example, a dc power supply 74a and a changeover switch 74 b. The dc power supply 74a is electrically connected to the electrode 71b of the electrostatic chuck 71. When a voltage is applied to the electrode 71b by the dc power supply 74a, an electric charge is generated on the substrate 100 side surface of the electrode 71 b. Accordingly, an electrostatic force is generated between the electrode 71b and the substrate 100, and the substrate 100 is attracted to the electrostatic chuck 71 by the generated electrostatic force.

The changeover switch 74b is electrically connected between the dc power supply 74a and the electrode 71b of the electrostatic chuck 71, and switches between suction and release of the substrate 100.

The cooling gas supply unit 75 supplies the cooling gas G1 to the grooves 71a1 through the gas supply holes 71a2a provided in the dielectric 71 a. That is, the cooling gas supply unit 75 supplies the cooling gas to the inside of the plurality of grooves 71a1 whose openings are covered with the film 71 c.

The cooling gas supply unit 75 includes, for example, a gas source 75a, a gas controller 75b, and an opening/closing valve 75 c. The gas source 75a may be, for example, a high-pressure bottle or the like containing the cooling gas G1. The gas source 75a may be, for example, a plant pipe. The cooling gas G1 may be helium or the like, for example.

The gas controller 75b can be disposed between the gas source 75a and the electrostatic chuck 71. The gas controller 75b controls at least one of the flow rate and the pressure of the cooling gas G1 supplied from the gas source 75 a. The gas controller 75b may be, for example, an MFC or the like.

For example, when the resist mask 103 is removed, the gas controller 75b can control at least one of the flow rate and the pressure of the cooling gas so that the surface temperature of the substrate 100 becomes 80 ℃. For example, the gas controller 75b can control the surface temperature of the substrate 100 to 80 ℃ or lower by controlling the temperature of the electrostatic chuck 71 to 45 ℃ or lower. For example, the gas controller 75b can control the supply flow rate of the cooling gas G1 so that the detected value of the pressure in the space defined by the pellicle 71c and the plurality of grooves 71a1, which is detected by a pressure gauge, not shown, becomes 400Pa to 2000Pa, thereby making the surface temperature of the substrate 100 80 ℃ or lower.

The on-off valve 75c can be provided between the gas controller 75b and the electrostatic chuck 71. The opening/closing valve 75c controls the start and stop of the supply of the cooling gas G1. The opening/closing valve 75c may be a two-way solenoid valve, for example. The gas controller 75b may also have a function of opening and closing the valve 75 c.

Here, as described above, the film 71c covers the openings of the plurality of grooves 71a 1. Therefore, the cooling gas G1 supplied to the plurality of grooves 71a1 cools the substrate 100 through the film 71 c. In this case, in order to enhance the cooling effect, the temperature of the cooling gas G1 is preferably equal to or lower than normal temperature (e.g., equal to or lower than 25 ℃).

If the cooling gas G1 is supplied to the space partitioned by the film 71c and the plurality of grooves 71a1, the cooling gas G1 directly contacts the film 71 c. Therefore, the heat transfer efficiency is better than that when the film 71c is cooled by the cooling gas G1 through the dielectric 71 a.

For example, the cooling gas supply unit 75 may further include a cooler 75d that cools the supplied cooling gas G1. The cooler 75d may be, for example, a heat exchanger that cools the cooling gas G1 so that the temperature of the cooling gas G1 becomes-20 ℃. Further, the liquefied cooling gas G1 may be vaporized to be the cooling gas G1. Thus, the cooling gas G1 at a temperature of-20 ℃ or lower can be supplied to the electrostatic chuck 71 without providing the cooler 75 d.

In the present embodiment, the air supply hole 71a2a and the air discharge hole 71a2b can be separated. This prevents the particles 200 having a particle diameter that may damage the device 102 from being generated, and also forms the flow of the cooling gas G1 in the space defined by the thin film 71c and the plurality of grooves 71a 1. Therefore, the cooling efficiency is improved.

The plasma processing apparatus 1 of the present embodiment is particularly suitable for plasma processing of the substrate 100 having the concave portion 101a1 on the back surface 101a of the susceptor 101.

When the thickness of the base 101 is the substrate 100 which is thin as a whole, the substrate 100 has low rigidity and is thus bent. Therefore, a glass substrate or a thin plate having a certain thickness is used to supplement rigidity.

In the substrate 100 of the present embodiment, the outer peripheral portion of the susceptor 101 is thick. Therefore, the substrate 100 of the present embodiment has higher rigidity than the substrate 100 in which the thickness of the susceptor 101 is small as a whole. Accordingly, the substrate 100 of the present embodiment does not need to be made rigid by a glass substrate or a thin plate. Therefore, the organic film 104 may have a thickness that can protect the device 102. That is, the thickness of the organic film 104 of the substrate 100 of the present embodiment can be made smaller than the thickness of a glass substrate or a thin plate.

The thickness of the organic film 104 is very thin compared to a glass substrate or a thin plate. Therefore, the electrostatic chuck 71 has a larger force for attracting the substrate 100 of the present embodiment than when attracting the substrate 100 protected by a glass substrate or a thin plate. Therefore, even if the pressure in the space defined by the film 71c and the plurality of grooves 71a1 is made higher than the pressure at the time of suction of the substrate 100 protected by the glass substrate or the thin plate, the substrate 100 of the present embodiment is not separated from the electrostatic chuck 71. That is, even if the cooling gas G1 having a higher pressure than that of the conventional art is supplied to the space defined by the film 71c and the plurality of grooves 71a1, the film 71c is not expanded by the pressure of the cooling gas G1. As described above, the cooling gas G1 can be supplied to the space defined by the film 71c and the plurality of grooves 71a1 under a higher pressure than in the conventional case. Therefore, the cooling efficiency of the substrate 100 of the present embodiment is better than that of the substrate 100 protected by a glass substrate or a thin plate.

In the present embodiment, the thickness of the organic film 104 can be set to 3 μm or more and 10 μm or less. By setting the thickness of the organic film 104 within the above range, the cooling gas G1 can be supplied under a higher pressure than in the conventional case. Therefore, the cooling efficiency is better than that of the substrate 100 protected by a glass substrate or a thin plate. In addition, the thickness of the organic film 104 of the substrate 100 in which the device 102 is protected by the organic film is small. Therefore, heat transfer to the susceptor 101 is preferable. Thus, the substrate 100 in which the device 102 is protected by the organic film 104 has better cooling efficiency than the substrate 100 protected by a glass substrate or a thin plate.

The embodiments are exemplified above. However, the present invention is not limited to the above description.

In the above-described embodiments, a person skilled in the art can add, delete, or change the design of the components or add, omit, or change the conditions of the steps as appropriate, as long as the features of the present invention are included in the scope of the present invention.

Further, each element included in each of the above embodiments may be combined as long as the technique is technically feasible, and the technique in which these are combined is also included in the scope of the present invention as long as the feature of the present invention is included.

For example, although the removal of the resist mask 103 is described as an example of the plasma treatment, the plasma treatment is not limited thereto. For example, a process of etching the rear surface 101a of the susceptor 101 of the substrate 100 and a process of forming a metal film or an insulating film on the rear surface 101a of the susceptor 101 are also included in the plasma process.

For example, an opening may be provided in a portion of the film 71c that faces the air supply hole 71a2 a. Thus, the cooling efficiency of the substrate 100 is improved.

For example, although the 1 st hole 71a2 is divided into the air supply hole 71a2a and the air discharge hole 71a2b, it may be used without being divided. For example, the gas G may be continuously supplied from the 1 st hole 71a2 during the plasma processing, and may be exhausted from the 1 st hole 71a2 after the plasma processing is completed.

Claims

1. A plasma processing apparatus for processing a substrate, the substrate comprising: a base; a plurality of devices provided on one surface of the base; an organic film provided on one surface of the base and covering the plurality of devices; and a resist mask provided on the other surface of the base,

an electrostatic chuck on which the side of the substrate on which the organic film is formed is placed,

The electrostatic chuck has: a dielectric having a plurality of grooves opened on a surface thereof;

an electrode provided inside the dielectric;

a thin film provided on the surface of the dielectric, covering the openings of the plurality of grooves, and containing a fluororesin;

and a joint portion provided between the film and the dielectric,

when a dimension of the dielectric in a direction parallel to the surface is D1(mm) and a dimension of the film in a direction parallel to the surface is D2(mm), the following formula D2(mm) < D1(mm) is satisfied.

2. The plasma processing apparatus according to claim 1, wherein the organic film has a thickness of 5 μm or more and 10 μm or less.

3. The plasma processing apparatus according to claim 1 or 2, wherein when a dimension of the organic film in a direction parallel to the surface is D3, the following formula D2(mm) < D3(mm) is satisfied.

4. The plasma processing apparatus according to any one of claims 1 to 3, wherein L is a distance between the peripheral end surface of the dielectric and the peripheral end surface of the thin film, and 0.5 mm. ltoreq. L.ltoreq.5 mm is satisfied.

5. The plasma processing apparatus according to any one of claims 1 to 4, wherein a total of a thickness of the joint portion and a thickness of the thin film is 100 μm or less.

6. The plasma processing apparatus according to any one of claims 1 to 5, further comprising a cooling gas supply unit capable of supplying a cooling gas into the plurality of grooves having the openings covered with the thin film.