Etching Equipment

Abstract

To provide an etching device containing etching gas supply means of supplying a plasma etching gas to a plate-like processed material held by a chuck table.SOLUTION: In an etching device 50, etching gas supply means 54 comprises at least: a shower head 54b that ejects an etching gas to an opposite surface to a wafer 10 held by a chuck table 55; movement means (a motor 58, a ball screw 59, and a lifting part 60) that makes the shower head approach and separate to / from the chuck table. When opening a door 67 and entering a wafer into the chamber 53, and holding them by the chuck table, the shower head is separated from the chuck table, and when making the chamber in vacuum by closing the door, the wafer is coated so as to be approached to the shower head to the wafer held by the chuck table from the execution of the plasma etching processing in order to protect the shower head from a winding of a particle remaining in the chamber.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an etching apparatus including an etching gas supply means for supplying an etching gas in the form of plasma to a plate-shaped workpiece held on a chuck table. [Background technology]

[0002] A wafer having a plurality of devices such as ICs and LSIs formed on its surface defined by dividing lines is separated into individual device chips by a dicing machine and used in electrical equipment such as mobile phones and personal computers.

[0003] Also, a technique has been proposed in which a wafer is divided into individual devices by etching using a fluorine-based gas plasma (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-108428 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the chamber constituting the etching apparatus is controlled so that the gas inside is discharged every time an etching process is performed and the chamber is kept as clean as possible, but fine particles generated by etching remain inside the chamber, and it is difficult to completely remove these particles. Furthermore, when the pressure inside the chamber is reduced to create a vacuum during the etching process, the air flow inside the chamber becomes turbulent, causing the particles that have remained inside the chamber to rise up and adhere to the upper surface of the workpiece to be etched, resulting in non-uniform etching and a decrease in the quality of the etching process.

[0006] The present invention has been made in view of the above circumstances, and its main technical object is to provide an etching apparatus that can solve the problem of non-uniform etching and reduced quality. [Means for solving the problem]

[0007] In order to solve the above-mentioned main technical problem, according to the present invention, there is provided an etching apparatus comprising a chamber provided with a door, a chuck table provided within the chamber and holding a plate-shaped workpiece, and etching gas supply means for supplying a plasmatized etching gas to the workpiece held on the chuck table, the etching gas supply means including at least a shower head facing the workpiece held on the chuck table and spraying an etching gas thereto, and a moving means for moving the showerhead toward and away from the chuck table, and when the door is opened and the workpiece is advanced into the chamber and held on the chuck table, the showerhead is moved away from the chuck table, and when the door is closed and the chamber is evacuated, the showerhead is moved closer to the workpiece held on the chuck table than when plasma etching is performed, thereby covering the workpiece and protecting the workpiece from being blown up by particles remaining in the chamber.

[0008] It is preferable to maintain the position of the showerhead in the protected state for a predetermined time until the gas flow stabilizes after the etching gas is sprayed from the showerhead. Effect of the Invention

[0009] The etching apparatus of the present invention is an etching apparatus comprising: a chamber provided with a door; a chuck table provided within the chamber for holding a plate-shaped workpiece; and an etching gas supply means for supplying a plasmatized etching gas to the workpiece held on the chuck table. The etching gas supply means comprises at least a shower head which faces the workpiece held on the chuck table and sprays an etching gas thereto; and a moving means for moving the showerhead towards and away from the chuck table. When the door is opened to allow the workpiece to enter the chamber and be held on the chuck table, the showerhead is moved away from the chuck table, and when the door is closed to evacuate the chamber, the showerhead is moved closer to the workpiece held on the chuck table than when plasma etching is performed, so as to cover the workpiece and to protect the workpiece from being blown up by particles remaining in the chamber. Therefore, even if particles are blown up due to disturbances in the airflow when evacuating the chamber, the particles are prevented from adhering to the upper surface of the workpiece to be etched, and the problem of non-uniform etching and reduced quality is eliminated. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2A is a perspective view showing a wafer and a substrate which are workpieces, and FIG. 2B is an enlarged cross-sectional view of a portion of the wafer and the substrate shown in FIG. [Diagram 2] FIG. 2(a) is an oblique view showing how the resist film of the wafer shown in FIG. 1 is removed along the planned dividing lines; FIG. 2(b) is an enlarged cross-sectional view of a portion of the wafer shown in FIG. 1; and FIG. 2(c) is an oblique view of the wafer from which the resist film has been removed along all of the planned dividing lines. [Diagram 3] 1 is a schematic cross-sectional view of a portion of an etching apparatus according to an embodiment of the present invention. [Figure 4] 4 is a schematic diagram showing a state in which a door is opened and a wafer is introduced into a chamber in the etching apparatus of FIG. 3. [Diagram 5]5 is a schematic view showing a manner in which a door is closed in the etching apparatus shown in FIG. 4. [Figure 6] 6 is a schematic diagram showing a manner in which a shower head is brought close to a chuck table in the etching apparatus shown in FIG. 5. [Figure 7] 7 is a schematic diagram showing a mode in which an etching gas is supplied in a state in which a shower head is brought close to a chuck table in the etching apparatus shown in FIG. 6. [Figure 8] 8 is a schematic diagram showing a mode in which plasma etching is performed in the etching apparatus shown in FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an etching apparatus configured based on the present invention will be described in detail with reference to the accompanying drawings.

[0012] A plate-shaped workpiece etched by an etching apparatus 50 of the present embodiment described later is, for example, a wafer 10 shown in FIG. 1(a). The wafer 10 is made of a silicon (Si) substrate having a thickness of, for example, 100 μm, and a plurality of devices 12 are formed on a front surface 10a partitioned by a division line 14. A substrate 20 for supporting the wafer 10 is attached to a rear surface 10b of the wafer 10. The substrate 20 is preferably selected from a hard plate such as glass, polyethylene terephthalate, or ceramics. FIG. 1(b) shows an enlarged part of a cross section after the wafer 10 and the substrate 20 in FIG. 1(a) are integrated, and a resist film 16 is coated over the entire front surface 10a of the wafer 10.

[0013] Once the wafer 10 with the substrate 20 attached thereto has been prepared, a resist film removal process is carried out to remove the resist film 16 from above the intended division line 14, which will be the starting point for dividing the wafer 10 into individual devices 12. When carrying out the resist film removal process, for example, as shown in FIG. 2(a), the wafer 10 is positioned directly under a laser beam application means 30 (only a portion of which is shown). The laser beam application means 30 comprises a holding means (not shown) and a condenser 32 which condenses and irradiates a laser beam LB onto the wafer 10 held by the holding means. The holding means comprises an X-axis feed means which feeds the holding means and the condenser 32 relatively in the X-axis direction for processing, and a X-axis feed means which feeds the holding means and the condenser 32 relatively in the X-axis direction for processing. The holding means is provided with a Y-axis feed means for feeding the workpiece in the Y-axis direction perpendicular to the axial direction, and a rotary drive means for rotating the holding means (both not shown).

[0014] The wafer 10 transported to and held by the holding means of the laser beam application means 30 has the surface 10a coated with the resist film 16 facing upward, and the substrate 20 side is suction-held by the holding means. Next, alignment is performed by alignment means (not shown), which detects the positions of the division lines 14 formed on the surface 10a, and the wafer 10 is rotated by the rotation drive means to align the division lines 14 in a predetermined direction with the X-axis direction. Information on the detected positions of the division lines 14 is stored in control means (not shown).

[0015] Based on the position information detected by the above-mentioned alignment step, the condenser 32 of the laser beam application means 30 is positioned at the processing start position of the division lines 14 in a predetermined direction, and as shown in FIG. 2(b), a spot of a laser beam LB having a wavelength absorbent for the resist film 16 is positioned and irradiated on the resist film 16 coated on the surface 10a of the wafer 10, and the wafer 10 is processed and fed in the X-axis direction to perform ablation processing along the predetermined division lines 14 of the wafer 10 to remove the resist film 16 and form a removed groove 100. When removing the resist film 16 in a predetermined width along the division lines 14, ablation processing is repeatedly performed along the predetermined division lines 14 as necessary to form a removed groove 100 of a predetermined width. After the removed groove 100 is formed, the wafer 10 is indexed and fed in the Y-axis direction by the interval of the division lines 14, and the unprocessed division lines 14 adjacent in the Y-axis direction are positioned directly under the condenser 32. Then, in the same manner as described above, the spot of the laser beam LB is positioned on the dividing lines 14 of the wafer 10 and irradiated, and the wafer 10 is machined and fed in the X-axis direction to form the removed grooves 100. Similarly, the wafer 10 is machined and fed in the X-axis direction and the Y-axis direction to form the same removed grooves 100 as described above along all the dividing lines 14 along the X-axis direction. Next, the wafer 10 is rotated 90 degrees to align the unmachined dividing lines 14 perpendicular to the dividing lines 14 along which the removed grooves 100 have already been formed, with the X-axis direction. Then, the spot of the laser beam LB is positioned on each of the remaining dividing lines 14 in the same manner as described above and irradiated, and as shown in FIG. 2(c), the removed grooves 100 are formed by removing the resist film 16 along all the dividing lines 14 formed on the front surface 10a of the wafer 10.

[0016] The method of removing the resist film 16 along the planned dividing lines 14 of the wafer 10 is not limited to the method of removing the resist film 16 using the above-mentioned laser beam application means 30. For example, after covering the entire surface 10a of the wafer 10 with the resist film 16, an appropriate mask may be applied and only the parts corresponding to the planned dividing lines 14 may be exposed to light to remove the resist film 16, or after covering the entire surface 10a of the wafer 10 with the resist film 16, a cutting blade may be applied to the parts corresponding to the planned dividing lines 14 to remove the resist film 16.

[0017] As described above, once the wafer 10 suitable for etching by the etching apparatus 50 of the present embodiment is prepared, it is transferred to the etching apparatus 50 of the present embodiment shown in Fig. 3. The etching apparatus 50 of the present embodiment will be described in more detail with reference to Fig. 3.

[0018] The etching apparatus 50 of this embodiment is an apparatus for performing plasma etching on a workpiece, and is equipped with an etching processing section 52 including a chamber 53 provided with a door 67, a chuck table 55 provided in the chamber 53 for holding a plate-shaped workpiece, and an etching gas supply means 54 for supplying an etching gas in the form of plasma to the workpiece held on the chuck table 55. A fluorine-based gas used in the plasma etching process is supplied to the etching processing section 52 from a gas supply section 51 at any timing and in any amount.

[0019] As shown in FIG. 3, the etching processing section 52 is configured to accommodate an etching gas supply means 54 on the upper side of a chamber 53 in which plasma etching is performed, and a chuck table 55 for holding a workpiece to be etched on the lower side.

[0020] The etching gas supply means 54 has a shaft 54a inserted into the chamber 53 via a bearing 56, and a gas circulation hole 57 is formed inside the shaft 54a, which is connected to the gas supply unit 51 and is connected to a jetting unit 57a formed in the shower head 54b and made of a porous material. The etching gas supply means 54 is driven by a motor 58 to rotate a ball screw 59, and can be raised and lowered as an elevation unit 60 having a nut screwed onto the ball screw 59 rises and falls. The motor 58, the ball screw 59, and the elevation unit 60 function as a moving unit for moving the shower head 54b toward and away from the chuck table 55.

[0021] The chuck table 55 has a shaft portion 55a rotatably inserted through a bearing 61 of the chamber 53, and a cooling passage 65 that communicates with a cooling section 64 and circulates cooling water inside the chuck table 55 is formed inside the shaft portion 55a. An electrostatic chuck 55c having a plurality of electrodes embedded therein is disposed on an upper surface 55b of the chuck table 55, and a voltage is applied to the electrostatic chuck 55c from a power source 62 electrically connected through the inside of the shaft portion 55a, thereby electrically adsorbing a plate-shaped workpiece placed on the electrostatic chuck 55c.

[0022] An opening 66 serving as an entrance for loading and unloading the wafer 10 to be etched is formed on the side of the chamber 53, and a door 67 is disposed on the outside of the opening 66, which opens and closes the opening 66 by ascending and descending. The door 67 is fixed to the tip of a piston rod 69 which is ascended and descended by a cylinder 68, and is ascended and descended by the cylinder 68.

[0023] An exhaust port 71 communicating with a gas exhaust unit 70 is formed at the bottom of the chamber 53, and gas inside the chamber 53 can be exhausted from the exhaust port 71. A high-frequency power source 72 is connected to the etching gas supply means 54 and the chuck table 55, and the fluorine-based gas supplied to the etching gas supply means 54 can be turned into plasma. The electric energy supplied by the high-frequency power source 72 to the etching gas supply means 54 is set to, for example, 3000 W, and the electric energy supplied to the chuck table 55 is set to, for example, 100 W. Each operating unit of the gas supply unit 51 and the etching processing unit 52 of the etching apparatus 50 described above is controlled by a control unit (not shown).

[0024] The etching apparatus 50 of this embodiment has a configuration generally as described above, and the operation when etching the wafer 10 using the etching apparatus 50 described with reference to FIG. 3 will be described below.

[0025] First, as shown in FIG. 4, the cylinder 68 is operated to lower the door 67 in the direction indicated by the arrow R1 to open the opening 66. Next, the wafer 10 is introduced into the chamber 53 from the direction indicated by the arrow R2 relative to the opening 66. Then, the wafer 10 is placed and held on the electrostatic chuck 55c to which a voltage is applied from the voltage source 62, with the side covered with the resist film 16 facing upward and the side to which the substrate 20 is attached facing downward. When holding the wafer 10 on the chuck table 55 in this manner, the moving means including the motor 58 is operated to move the shower head 54b including the ejection part 57a of the etching gas supply means 54 away from the chuck table 55. The position of the shower head 54b at this time is set to a position higher than the position of the shower head 54 when performing the etching process, and is positioned at a height of about 100 mm with respect to the upper surface 55b of the chuck table 55, for example.

[0026] As described above, when the wafer 10 is advanced into the chamber 53 and held on the chuck table 55, as shown in FIG. 5, the cylinder 68 is operated to move the door 67 in the direction indicated by the arrow R3 to close the opening 66 and isolate the inside of the chamber 53 from the outside. Thereafter, as shown in FIG. 6, the gas exhaust unit 70 is operated to exhaust the gas inside the chamber 53 as indicated by the arrow R4 to reduce the pressure inside the chamber 53 to a vacuum state (for example, about 50 Pa). Also, before starting to reduce the pressure inside the chamber 53 as described above, as shown in FIG. 6, the moving unit is operated by the control unit to lower the lift unit 60 in the direction indicated by the arrow R5, and at the same time, the shower head 54b is lowered in the direction indicated by the arrow R6. As a result, the lower surface of the shower head 54b is brought closer to the wafer 10 held on the chuck table 55 than when the etching process is performed, and the side of the front surface 10a of the wafer 10 on which the resist film 16 is formed is covered and protected by the shower head 54b. At this time, the distance between the shower head 54b and the resist film 16 on the wafer 10 is set to, for example, about 1 mm. As a result, when the gas exhaust unit 70 is operated to exhaust the gas in the chamber 53 and reduce the pressure, even if an air current is generated inside the chamber 53 and particles remaining inside the chamber 53 are blown up, the particles do not enter the gap between the shower head 54b and the resist film 16 on the wafer 10, and the particles are prevented from adhering to the surface of the resist film 16.

[0027] As described above, after the inside of the chamber 53 is depressurized and a vacuum state is reached, the height position of the shower head 54b is maintained in the above-mentioned protected state, and the gas exhaust unit 70 is operated to maintain the depressurized state, while a fluorine-based gas is supplied from the gas supply unit 51 to the gas circulation hole 57. As shown in FIG. 7, the gas supply unit 51 includes, for example, a first gas storage means 51a for storing sulfur hexafluoride (SF6) as a fluorine-based gas, a second gas storage means 51b for storing octafluorocyclobutane (C4F8), and a three-way valve V for switching the fluorine-based gas supplied to the gas circulation hole 57. The three-way valve V is switched to supply one of the fluorine-based gases to the ejection part 57a of the shower head 54b according to the material forming the wafer 10, and the etching gas is ejected from the ejection part 57a. When the etching gas is ejected, the high frequency power supply 72 is operated to apply a high frequency voltage to the etching gas supply means 54 and the chuck table 55 as described above, and an etching gas obtained by converting a fluorine-based gas into plasma is ejected from the ejection part 57a of the shower head 54b. In this embodiment, the three-way valve V is switched in the gas supply part 51 so that sulfur hexafluoride SF6 is selected, and sulfur hexafluoride SF6 flows in the direction indicated by the arrow R7, and the etching gas G converted into plasma is ejected from the ejection part 57a of the shower head 54b. When the etching gas G is ejected in this manner, the position of the shower head 54b is kept in the protected state as described above for a predetermined time (for example, about one minute) from the start of ejection. As a result, even if the airflow in the chamber 53 is disturbed due to the etching gas G being ejected from the ejection portion 57a ​​and particles remaining inside the chamber 53 are stirred up, the particles are prevented from adhering to the resist film 16 of the wafer 10 held on the chuck table 55.

[0028] As described above, when it is determined that the air flow in the chamber 53 is stabilized by the etching gas G being ejected from the ejection part 57a and the etching gas G being exhausted from the gas exhaust part 70 and a predetermined time has elapsed, the moving means including the motor 58 is operated to raise the lifting part 60 in the direction indicated by the arrow R8, and the shower head 54b of the etching gas supplying means 54 is raised in the direction indicated by the arrow R9, and positioned at a predetermined height suitable for etching (for example, 40 mm above the upper surface of the chuck table 55). As a result, the etching gas G in plasma form is supplied onto the resist film 16 forming the upper surface of the wafer 10, and etching is performed along the above-mentioned removal grooves 100, i.e., the planned division lines 14, on the upper surface of the wafer 10 where the resist film 16 has been removed and is not covered, and the wafer 10 is divided into individual devices 12.

[0029] According to the above-described embodiment, even if the airflow is disturbed and particles are stirred up when the chamber 53 is evacuated, the particles are prevented from adhering to the upper surface of the wafer to be etched, and the problem of non-uniform etching and reduced quality is eliminated. Also, after the chamber 53 is evacuated, when the plasmatized etching gas G is supplied into the chamber 53, the shower head 54b is brought close to the upper surface of the wafer 10 to cover the wafer 10 until the airflow becomes stable. Therefore, even if the airflow in the chamber 53 is disturbed by the supply of the etching gas G and particles are stirred up, the problem of the particles adhering to the upper surface of the wafer 10 to be etched is eliminated.

[0030] In the above embodiment, the etching apparatus 50 is used to perform plasma etching from the front surface 10a side of the wafer 10, and the wafer 10 is divided into individual devices 12 along the division lines 14 from which the resist film 16 has been removed, but the present invention is not limited to this. For example, the present invention can be applied to an etching process performed to remove a damage layer consisting of grinding distortion formed by the grinding process from the back surface 10b side of the wafer 10 that has been ground to a desired thickness, and the same effects as those described above can be obtained. [Explanation of symbols]

[0031] 10: Wafer 12: Device 14: Planned division line 16: Resist film 20: Substrate 30: Laser beam irradiation means 32: Concentrator 50: Etching equipment 51: Gas supply section 52: Etching processing section 53: Chamber 54: Etching gas supply means 54a: Shaft 54b: Shower head 55: Chuck table 55a: Shaft 55b:Top surface 55c: Electrostatic chuck 56: Bearing 57: Gas flow hole 57a: Spout part 58: Motor 59: Ball screw 60: Lifting section 61: Bearing 62: Voltage source 64: Cooling section 65: Cooling path 66: Opening 67: Door 68: Cylinder 69: Piston rod 70: Gas exhaust section 71: Exhaust port 100: Removal groove G: Etching gas V: Three-way valve

Claims

1. An etching apparatus including a chamber having a door, a chuck table disposed in the chamber and holding a plate-shaped workpiece, and an etching gas supply means for supplying an etching gas in the form of plasma to the workpiece held on the chuck table, the etching gas supply means includes at least a shower head that faces the workpiece held on the chuck table and sprays the etching gas, and a moving means that moves the shower head toward and away from the chuck table; When the door is opened and the workpiece is introduced into the chamber and held on the chuck table, the shower head is moved away from the chuck table; When the door is closed to evacuate the chamber, the shower head is brought closer to the workpiece held on the chuck table than when performing plasma etching processing, covering the workpiece and putting the workpiece into a protective state to protect it from the lift-up of particles remaining in the chamber.

2. 2. The etching apparatus according to claim 1, wherein the position of the shower head is maintained in the protected state for a predetermined time until an etching gas is sprayed from the shower head and an air flow becomes stable.

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