Workpiece processing method

Abstract

To provide a workpiece processing method that can increase the processing speed.SOLUTION: A workpiece processing method uses a vacuum chamber that separates the interior from the atmosphere to process a plate-shaped workpiece contained inside using plasma-converted gas, and includes a holding step 101 of holding the workpiece on a holding table inside the vacuum chamber, a heating step 102 of heating the workpiece held on the holding table to a temperature of 150°C or higher and 660°C or lower using a heating mechanism, a depressurizing step 103 of reducing the pressure inside the vacuum chamber that contains the workpiece held on the holding table to 100 Pa or lower, and a processing step 104 of supplying plasma-converted gas to the heated workpiece and dry-etching the workpiece.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for processing a workpiece.

Background Art

[0002] There is known a dry etching technique in which a plate-shaped workpiece such as a semiconductor device wafer having a device formed on its surface is etched using a gas in a plasma state (see, for example, Patent Document 1).

[0003] In this dry etching technique, a vacuum chamber is used to remove unnecessary gas inside, and the inside is filled only with the gas used for various processes including etching, and the pressure is set to 1000 Pa or less at which plasma can be generated, and then the workpiece is processed with the plasma.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional processing methods described in Patent Document 1 and the like, the processing speed is not sufficient, and a higher processing speed has been demanded.

[0006] An object of the present invention is to provide a method for processing a workpiece that can achieve a higher processing speed.

Means for Solving the Problems

[0007] In order to solve the above-described problems and achieve the object, a method for processing a workpiece according to the present invention is a method for processing a workpiece in which a plate-shaped workpiece accommodated therein is processed with a gas made into plasma using a vacuum chamber that partitions the inside from the atmosphere, the method including: a holding step of holding the workpiece with a holding table in the vacuum chamber; a heating step of heating the workpiece held on the holding table to a temperature of 150° C. or higher and 660° C. or lower by a heating mechanism; a decompression step of decompressing the inside of the vacuum chamber in which the workpiece held on the holding table is accommodated to 100 Pa or lower; and a processing step of supplying a gas made into plasma to the heated workpiece to dry-etch the workpiece.

[0008] In the above processing method, the material of the workpiece may be diamond.

[0009] In the above processing method, the gas may be oxygen or a compound gas containing oxygen atoms.

[0010] In the above processing method, in the processing step, the gas may be made into plasma by glow discharge.

[0011] In the above processing method, in the processing step, high-frequency power may be applied to a dielectric coil, and the gas may be made into plasma by interaction with a magnetic field formed in the dielectric coil.

[0012] In the above processing method, in the processing step, the gas may be made into plasma by microwaves.

Effects of the Invention

[0013] The present invention has an effect that the processing speed can be increased.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

DETAILED DESCRIPTION OF THE INVENTION

[0015] The embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the content described in the following embodiments. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Also, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[0016] 〔Embodiment 1〕 The method for machining a workpiece according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of the workpiece to be machined in the method for machining a workpiece according to Embodiment 1. FIG. 2 is a flowchart showing the flow of the method for machining a workpiece according to Embodiment 1. FIG. 3 is a cross-sectional view schematically showing the etching apparatus during the machining of the method for machining a workpiece shown in FIG. 2.

[0017] (Workpiece) The processing method according to Embodiment 1 is a method for processing the workpiece 1 shown in FIG. 1. The workpiece 1 to be processed according to Embodiment 1 is, for example, a wafer such as a disk-shaped semiconductor wafer or an optical device wafer having a base material 2 (corresponding to a material) made of silicon, sapphire, gallium nitride, gallium arsenide, diamond, or the like. As shown in FIG. 1, devices 5 are formed in each region of the workpiece 1 partitioned in a grid pattern by a plurality of division planned lines 4 formed in a grid pattern on the circular surface 3.

[0018] The device 5 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), or a memory (semiconductor memory device).

[0019] After the workpiece 1 is thinned to a predetermined thickness by performing grinding or the like on the back surface 6 on the back side of the surface 3, dry etching is performed on the back surface 6 to release the internal stress generated during the grinding process. The workpiece 1 is divided into individual devices 5 along the division planned lines 4. In Embodiment 1, the base material 2 of the workpiece 1 is made of diamond.

[0020] (Processing Method of Workpiece) The processing method of the workpiece according to Embodiment 1 includes a holding step 101, a heating step 102, a decompression step 103, and a processing step 104, as shown in FIG. 2. The processing method of the workpiece according to Embodiment 1 uses the vacuum chamber 11 of the etching device 10 shown in FIG. 3 that airtightly partitions the inside from the atmosphere, and processes the workpiece 1 accommodated inside the vacuum chamber 11 with the plasma gas 52 to release the internal stress of the workpiece 1 generated during the grinding process.

[0021] (Etching Device) First, the etching apparatus 10 shown in FIG. 3 will be described. As shown in FIG. 3, the etching apparatus 10 includes a rectangular parallelepiped vacuum chamber 11, a holding table 20, a plasma generation electrode 30, and a control unit (not shown).

[0022] The vacuum chamber 11 has a processing space 12 (corresponding to the inside) formed therein for accommodating the workpiece 1. The vacuum chamber 11 is provided with an opening (not shown) for loading and unloading the workpiece 1 and an opening / closing door (not shown) for opening and closing the opening. When the opening is closed by the opening / closing door, the processing space 12 is hermetically partitioned from the atmosphere outside the vacuum chamber 11.

[0023] Also, the vacuum chamber 11 has an exhaust cylinder 40 connected to the bottom wall 13 for communicating the inside and outside of the vacuum chamber 11. The exhaust cylinder 40 is provided with a pressure regulating valve 41, and an exhaust mechanism 42 such as a vacuum pump is connected thereto.

[0024] Further, the vacuum chamber 11 has a gas supply cylinder 50 connected to one side wall 14 and connected to a gas supply source 51. The gas supply source 51 supplies a gas for dry etching into the vacuum chamber 11 through the gas supply cylinder 50. In Embodiment 1, when the base material 2 of the workpiece 1 is made of diamond, the gas supply source 51 supplies oxygen or a compound gas containing oxygen atoms as the gas. That is, in Embodiment 1, the gas supplied by the gas supply source 51 into the vacuum chamber 11 is oxygen or a compound gas containing oxygen atoms.

[0025] The holding table 20 and the plasma generation electrode 30 are arranged to face each other in the processing space 12 of the vacuum chamber 11. The holding table 20 is formed in a disk shape, and the upper surface is a holding surface 21 for holding the workpiece 1. Also, the holding table 20 is made of a conductive material and also functions as a lower electrode.

[0026] The holding table 20 has the workpiece 1 placed on the holding surface 21. In Embodiment 1, the holding table 20 has the surface 3 of the workpiece 1 placed on the holding surface 21. The holding table 20 is provided with an electrode (not shown) connected to a high-frequency power source (not shown). When power is applied from the high-frequency power source to the electrode, a dielectric polarization phenomenon is generated between the holding surface 21 and the workpiece 1, and the workpiece 1 is adsorbed and held on the holding surface 21 by the electrostatic adsorption force due to the polarization of charges. Also, the holding table 20 is connected to an external high-frequency power source different from the high-frequency power source that applies power to the electrode and the vacuum chamber 11.

[0027] Further, the holding table 20 is provided with a heating mechanism 22 for heating the holding surface 21. By heating the holding surface 21, the heating mechanism 22 heats the workpiece 1 adsorbed and held on the holding surface 21.

[0028] The plasma generation electrode 30 is made of a conductive material, formed in a disk shape, and has a circular end face facing the holding surface 21 of the holding table 20 within the processing space 12 in the vacuum chamber 11. The plasma generation electrode 30 is connected to a high-frequency power source (not shown) outside the vacuum chamber 11.

[0029] The control unit controls each component of the etching apparatus 10 to perform dry etching on the workpiece 1 in the etching apparatus 10. The control unit is a computer having an arithmetic processing unit with a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory), and an input / output interface device. The arithmetic processing unit of the control unit performs arithmetic processing according to a computer program stored in the storage device, and outputs a control signal for controlling the etching apparatus 10 to each component of the etching apparatus 10 via the input / output interface device.

[0030] The control unit is also connected to a display unit composed of a liquid crystal display device or the like that displays various types of information, images, etc., and an input unit used when an operator registers processing content information or the like. The input unit is composed of at least one of a touch panel provided on the display unit and an external input device such as a keyboard.

[0031] (Holding Step) Next, the holding step 101 will be described. The holding step 101 is a step of holding the workpiece 1 on the holding table 20 in the vacuum chamber 11. In Embodiment 1, in the holding step 101, the etching apparatus 10 has the opening opened by the opening / closing door, and the workpiece 1 is carried into the processing space 12 by a conveying unit (not shown), and the surface 3 side of the workpiece 1 is placed on the holding surface 21 of the holding table 20.

[0032] In Embodiment 1, in the holding step 101, the etching apparatus 10 applies electric power from a high-frequency power source to the electrode in the holding table 20 to adsorb and hold the surface 3 of the workpiece 1 on the holding surface 21. In Embodiment 1, in the holding step 101, the etching apparatus 10 closes the opening with the opening / closing door to keep the processing space 12 in the vacuum chamber 11 airtight.

[0033] (Heating Step) Next, the heating step 102 will be described. The heating step 102 is a step of heating the workpiece 1 held on the holding table 20 by the heating mechanism 22 at a temperature of 150°C or higher and 660°C or lower. In Embodiment 1, in the heating step 102, the etching apparatus 10 heats the holding table 20 by the heating mechanism 22 and heats the workpiece 1 via the holding table 20 at a temperature of 150°C or higher and 660°C or lower. In Embodiment 1, in the heating step 102, the reason for heating the workpiece 1 at a temperature of 150°C or higher and 660°C or lower is that if the temperature for heating the workpiece 1 is less than 150°C, the processing speed in the processing step 104 cannot be improved, and if the temperature for heating the workpiece 1 exceeds 660°C, it will have an adverse effect on the device 5 on the surface 3 of the workpiece 1.

[0034] (Pressure reduction step) Next, the pressure reduction step 103 will be described. The pressure reduction step 103 is a step of reducing the pressure in the vacuum chamber 11 in which the workpiece 1 held on the holding table 20 is accommodated to 50 Pa or less. In Embodiment 1, in the pressure reduction step 103, the etching apparatus 10 operates the exhaust mechanism 42 to reduce the pressure in the vacuum chamber 11, and the control unit controls the pressure regulating valve 41 to reduce the processing space 12 to 0.5 Pa (absolute pressure) or higher and 100 Pa (absolute pressure) or lower. In Embodiment 1, in the pressure reduction step 103, the reason for reducing the pressure in the processing space 12 to 0.5 Pa or higher and 100 Pa or lower is that if the pressure for reducing the pressure in the processing space 12 is less than 0.5 Pa, it will lead to an increase in equipment cost due to the enlargement of the pressure reduction mechanism, and the processing speed (etching rate) will significantly decrease. Also, if the pressure for reducing the pressure in the processing space 12 exceeds 100 Pa, the plasma temperature will drop, and the processing speed (etching rate) will significantly decrease, or a huge amount of power will be required to maintain the plasma temperature. Further, if the pressure for reducing the pressure in the processing space 12 exceeds 50 Pa (absolute pressure), the plasma temperature will drop, and the processing speed (etching rate) will show a decreasing trend. Therefore, in the present invention, in the pressure reduction step 103, it is better to reduce the pressure in the processing space 12 to 0.5 Pa (absolute pressure) or higher and 50 Pa (absolute pressure) or lower.

[0035] (Processing Step) Next, the processing step 104 will be described. The processing step 104 is a step of supplying the plasmaized gas 52 to the heated workpiece 1 and dry-etching the workpiece 1. In Embodiment 1, in the processing step 104, the etching apparatus 10 supplies a gas containing oxygen or a compound gas containing oxygen atoms from the gas supply source 58 into the processing space 12 at a predetermined flow rate.

[0036] Also, in Embodiment 1, in the processing step 104, with the gas being supplied from the gas supply source 58 into the processing space 12, the etching apparatus 10 applies high-frequency power for generating and maintaining plasma from the high-frequency power source to the plasma generation electrode 30, and applies high-frequency power for attracting ions from the high-frequency power source to the holding table 20 which is the lower electrode. In Embodiment 1, in the processing step 104, a glow discharge occurs between the holding table 20 and the plasma generation electrode 30 in the processing space 12, and the gas is plasmaized by this glow discharge, and the plasmaized gas 52 is drawn to the side of the workpiece 1, and the back surface 6 of the workpiece 1 is plasma-etched (so-called dry-etching).

[0037] In Embodiment 1, in the processing step 104, a predetermined time for dry-etching the back surface 6 of the workpiece 1 is set in advance in the etching apparatus 10. In Embodiment 1, in the processing step 104, the etching apparatus 10 applies high-frequency power to the holding table 20 and the plasma generation electrode 30 while supplying the gas for a predetermined time to dry-etch the back surface 6 of the workpiece 1. Thus, in Embodiment 1, the processing step 104 plasmaizes the gas by glow discharge to dry-etch (also referred to as plasma-etching) the workpiece 1.

[0038] The processing method according to Embodiment 1 described above has the effect that the processing speed can be increased because the workpiece 1 is processed using the plasmaized gas 52 while heating the workpiece 1 at 150°C or higher and 660°C or lower in the processing step 104.

[0039] In addition, in the processing method according to Embodiment 1, since the base material 2 of the workpiece 1 is diamond and the gas is oxygen or a compound gas containing oxygen atoms, the processing speed in the processing step 104 can be increased.

[0040] 〔Embodiment 2〕 A method for processing a workpiece according to Embodiment 2 will be described with reference to the drawings. FIG. 4 is a cross-sectional view schematically showing an etching apparatus during processing of the method for processing a workpiece according to Embodiment 2. In FIG. 4, the same parts as those in Embodiment 1 are denoted by the same reference numerals, and the description thereof will be omitted.

[0041] The method for processing a workpiece according to Embodiment 2 includes, in the same manner as Embodiment 1, a holding step 101, a heating step 102, a pressure reduction step 103, and a processing step 104, and is the same as Embodiment 1 except that the method of plasmaizing the gas in the processing step 104 is different.

[0042] In the method for processing a workpiece according to Embodiment 2, in the same manner as Embodiment 1, in the holding step 101, the surface 3 side of the workpiece 1 is adsorbed and held on the holding table 20 of the etching apparatus 10-2 shown in FIG. 4. In the heating step 102, the workpiece 1 held on the holding table 20 is heated by the heating mechanism 22. In the pressure reduction step 103, the inside of the vacuum chamber 11 is depressurized. In Embodiment 2, in the processing step 104, the etching apparatus 10-2 is provided with a dielectric coil 53 connected to a high-frequency power source (not shown) on the outer periphery of a gas supply cylinder 50 connected to a ceiling wall 15 that supplies gas into the processing space 12 from a gas supply source 51 without providing a plasma generation electrode 30, and the gas is supplied into the processing space 12 from the gas supply source 58 while applying high-frequency power from the high-frequency power source to the dielectric coil 53.

[0043] In Embodiment 2, in processing step 104, the gas supplied into the processing space 12 is converted into plasma by the interaction between the etching apparatus 10-2 and the magnetic field formed in the dielectric coil 53, and the back surface 6 of the workpiece 1 is etched (so-called dry etching) with the plasma-converted gas 52. In Embodiment 2, in processing step 104, the etching apparatus 10-2 supplies gas from the gas supply source 58 into the processing space 12 while applying high-frequency power from the high-frequency power supply to the dielectric coil 53 for a predetermined time to dry-etch the back surface 6 of the workpiece 1.

[0044] Similar to Embodiment 1, the method for processing the workpiece according to Embodiment 2 processes the workpiece 1 using the plasma-converted gas 52 while heating the workpiece 1 at 150°C or higher and 660°C or lower in processing step 104, and thus has the effect of achieving a higher processing speed.

[0045] 〔Embodiment 3〕 The method for processing the workpiece according to Embodiment 3 will be described with reference to the drawings. FIG. 5 is a cross-sectional view schematically showing the etching apparatus during the processing of the method for processing the workpiece according to Embodiment 3. Note that the same reference numerals are given to the same parts as in Embodiment 1, and the description thereof will be omitted.

[0046] Similar to Embodiment 1, the method for processing the workpiece according to Embodiment 3 includes a holding step 101, a heating step 102, a depressurization step 103, and a processing step 104, and is the same as Embodiment 1 except that the method for converting the gas into plasma in the processing step 104 is different.

[0047] The processing method of the workpiece according to Embodiment 3 is the same as that of Embodiment 1. In the holding step 101, the surface 3 side of the workpiece 1 is adsorbed and held on the holding table 20 of the etching apparatus 10-3 shown in FIG. 5. In the heating step 102, the workpiece 1 held on the holding table 20 is heated by the heating mechanism 22. In the depressurization step 103, the inside of the vacuum chamber 11 is depressurized. In Embodiment 3, in the processing step 104, the etching apparatus 10-3 is provided with a microwave introduction mechanism 54 for introducing microwaves into the gas supply cylinder 50 connected to the side wall 14 that supplies gas into the processing space 12 from the gas supply source 51 without providing the plasma generation electrode 30. While introducing microwaves from the microwave introduction mechanism 54 into the gas supply cylinder 50, gas is supplied from the gas supply source 58 into the processing space 12.

[0048] In Embodiment 3, in the processing step 104, in the etching apparatus 10, the electron cyclotron resonance phenomenon occurs in the gas supply cylinder 50, the energy of the microwaves is efficiently absorbed by the gas, the gas is plasmaized, and the plasmaized gas 52 is supplied into the processing space 12. In Embodiment 3, in the processing step 104, the etching apparatus 10 etches the back surface 6 of the workpiece 1 with the plasmaized gas 52 (so-called dry etching). In Embodiment 2, in the processing step 104, the etching apparatus 10 supplies gas from the gas supply source 58 into the processing space 12 while introducing microwaves from the microwave introduction mechanism 54 into the gas supply cylinder 50 for a predetermined time to dry-etch the back surface 6 of the workpiece 1. Thus, in Embodiment 3, in the processing step 104, the gas is plasmaized by microwaves to dry-etch the workpiece 1.

[0049] The processing method of the workpiece according to Embodiment 3 is the same as that of Embodiment 1. In the processing step 104, since the workpiece 1 is processed using the plasmaized gas 52 while being heated to 150°C or higher and 660°C or lower, the effect of achieving a high processing speed can be obtained.

[0050] Note that the present invention is not limited to the above-described embodiments. That is, various modifications can be made and implemented without departing from the gist of the present invention. In the present invention, in the processing step 104, the planned division line 4 of the workpiece 1 may be plasma-etched to divide the workpiece 1 into individual devices 5.

Explanation of Reference Numerals

[0051] 1 Workpiece 2 Base material (raw material) 11 Vacuum chamber 20 Holding table 22 Heating mechanism 52 Plasma gas (plasma-treated gas) 53 Dielectric coil 101 Holding step 102 Heating step 103 Pressure reduction step 104 Processing step

Claims

1. A method for processing a workpiece, which uses a vacuum chamber that partitions the inside from the atmosphere and processes the plate-shaped workpiece accommodated inside with a gas converted into plasma, comprising: a holding step of holding the workpiece by a holding table in the vacuum chamber; a heating step of heating the workpiece held by the holding table at a temperature of 150°C or higher and 660°C or lower by a heating mechanism; a depressurization step of depressurizing the inside of the vacuum chamber in which the workpiece held by the holding table is accommodated to 100 Pa or lower; a processing step of supplying the gas converted into plasma to the heated workpiece and dry-etching the workpiece. The method for processing a workpiece according to claim 1, characterized by including the above steps.

2. The method for processing a workpiece according to claim 1, characterized in that the material of the workpiece is diamond.

3. The method for processing a workpiece according to claim 1, characterized in that the gas is oxygen or a compound gas containing oxygen atoms.

4. The method for processing a workpiece according to any one of claims 1 to 3, characterized in that in the processing step, the gas is converted into plasma by glow discharge.

5. The method for processing a workpiece according to any one of claims 1 to 3, characterized in that in the processing step, high-frequency power is applied to a dielectric coil, and the gas is converted into plasma by interaction with a magnetic field formed in the dielectric coil.

6. The method for processing a workpiece according to any one of claims 1 to 3, characterized in that in the processing step, the gas is converted into plasma by microwaves.

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