JP2018056486A - Mask forming method and wafer processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily produce a mask for etching.SOLUTION: A mask forming method includes: a tape adhering step of adhering a tape (80) to a wafer(W); a cut-out groove processing step of irradiating a tape adhered in the tape adhering step with laser beams having absorbent wavelength to form a cut-out groove (M); and a mask forming step of peeling off the tape along the cut-out groove processed in the cut-out groove processing step to form the tape remaining in the wafer without being peeled off in a mask.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a mask forming method and a wafer processing method of dividing a wafer by etching using the mask.

  In the semiconductor device manufacturing process, the wafer is partitioned by the division line, and the device chip is manufactured by dividing the wafer along the division line. As a wafer dividing method, a method of dividing with a cutting blade is known (see, for example, Patent Document 1), and the wafer is cut along a planned division line with a high-speed rotating cutting blade to cut the wafer. However, since the cutting blade that rotates at a high speed cuts into the scheduled dividing line of the wafer, the device is chipped due to the crushing force of the cutting blade.

  In view of this, a technique has been proposed in which a division line of a wafer is divided into individual devices by plasma etching (see, for example, Patent Document 2). In the method of Patent Document 2, a photoresist film is coated on the surface of a wafer, and a portion corresponding to the planned dividing line is exposed through a mask plate having a lattice-like mask pattern similar to the planned dividing line. The portion of the photoresist film corresponding to the planned division line is removed by development, and the portion corresponding to the planned division line is plasma etched using the remaining photoresist film corresponding to the device as a mask. Thereby, the wafer is divided into individual devices.

JP2015-159241A JP 2006-114825 A

  As described above, in the method of transferring a pattern to an object using a photoresist film as a mask, it is necessary to coat the object with the photoresist film, expose the object in a predetermined pattern, and then develop using a solvent. Therefore, there is a problem that the work becomes complicated.

  SUMMARY An advantage of some aspects of the invention is that it provides a mask forming method and a wafer processing method that can easily manufacture a mask for etching.

  The mask formation method of one embodiment of the present invention is a mask formation method, in which a tape is attached to a wafer, and a laser having an absorptive wavelength with respect to the tape attached in the tape attachment step. Cut-out groove processing step of forming a cut-out groove in the tape by irradiating light, and mask formation step of peeling the tape along the cut-out groove processed in the cut-out groove processing step, and the tape remaining on the wafer without being peeled off as a mask And comprising.

  A wafer processing method according to an aspect of the present invention is a wafer processing method in which a wafer is partitioned by a predetermined division line and a wafer device formed with a plurality of devices is masked, and the wafer is divided by dry etching the predetermined division line. There is a tape adhering process for adhering the tape to the wafer, and a laser beam having an absorptive wavelength is applied to the tape adhering to the wafer in the tape adhering process so that the cut groove is cut along the planned dividing line. Cut-out groove processing step to be formed, mask formation step in which the tape is peeled along the cut-out groove processed in the cut-out groove processing step, and the tape left on the surface of the wafer device without being peeled off is used as a mask, and the mask formation step Plasma that etches the wafer with the device masked to form split grooves along the planned split lines Comprising an etching step.

  According to this configuration, the tape is adhered to the wafer, a cut groove is formed in the tape by laser processing, and the tape is integrally peeled along the cut groove, whereby the tape remaining on the wafer surface is used as a mask. Available. Thus, a mask can be formed more easily than a conventional structure in which a photoresist film is coated and exposed, and further developed to form a mask. Since the tape is attached to the wafer with a glue layer, the mask can be easily removed by peeling off the tape. Further, the tape removal can be performed in a dry environment because it is not necessary to perform wet stripping performed by a conventional photoresist film, and the device is not adversely affected by heat because it is not necessary to perform ashing.

  According to the present invention, a mask for etching can be easily manufactured.

It is a cross-sectional schematic diagram of the wafer which concerns on this Embodiment. It is a figure which shows the tape sticking process which concerns on this Embodiment. It is a figure which shows the cut-out groove processing process which concerns on this Embodiment. It is a figure which shows the mask formation process which concerns on this Embodiment. It is a figure which shows the plasma etching process which concerns on this Embodiment. It is a figure which shows the peeling tape sticking process which concerns on this Embodiment. It is a figure which shows the mask removal process which concerns on this Embodiment. It is a figure which shows the mode of peeling of the tape in the mask formation process which concerns on this Embodiment. 1 is an overall schematic diagram of a plasma etching apparatus according to an embodiment.

  A wafer according to the present embodiment will be described with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view of a wafer according to the present embodiment.

  The wafer W is composed of a substrate 11 such as silicon and a device D formed on the surface of the substrate 11. A plurality of division lines L are formed in a lattice pattern on the surface of the substrate 11, and a plurality of devices D are formed in regions partitioned by the division lines. The wafer W is supported by the ring frame F via the protective tape T.

  Conventionally, when a device is manufactured by dividing a wafer along a division line, a photoresist film is formed on the surface of the device, and a portion corresponding to the division line is plasma-etched using the photoresist film as a mask. However, in order to form a photoresist film on the surface of the device, the surface of the wafer is covered with a photoresist film, and only the portion corresponding to the planned dividing line is selectively exposed and developed, and the photo resist film is formed on the surface of the device. It was necessary to leave a resist film. For this reason, a complicated process is required to form the photoresist film, and the work is complicated because a solvent is used for development. Therefore, in this embodiment, a tape is attached to the surface of the wafer, and the tape is cut out so as to surround the device by laser processing so that a mask can be easily formed on the surface of the device.

  Hereinafter, a wafer processing method according to the present embodiment will be described. The wafer processing method according to the present embodiment includes a tape adhering step, a cut groove processing step, a mask forming step, a plasma etching step, a peeling tape adhering step, and a mask removing step. 2 is a tape attaching process according to the present embodiment, FIG. 3 is a cut groove forming process, FIG. 4 is a mask forming process, FIG. 5 is a plasma etching process, FIG. 6 is a peeling tape attaching process, and FIG. It is a figure which shows a process.

  As shown in FIG. 2, a tape sticking process is first implemented in a tape sticking apparatus. The wafer W is supported by the ring frame F via the protective tape T, and is sucked and held by the holding table 61 via the protective tape T. A pressing roller 71 is provided above the holding table 61, and the tape 80 fed from the tape roll is pressed and adhered to the wafer W. The tape 80 is, for example, a dicing tape, and includes a tape base material 81 and a tape glue layer 82 formed on one surface of the tape base material 81. The tape base material 81 side of the tape 80 is in contact with the pressing roller, and the tape glue layer 82 side is adhered to the surface of the wafer W.

  As shown in FIG. 3, after the tape sticking step, a cut groove processing step is performed in the laser processing apparatus. As shown in FIG. 3A, the wafer W is supported by the ring frame F via the protective tape T, and is sucked and held by the holding table 62 via the protective tape T. Four clamp portions 91 are provided around the holding table 62, and the ring frame F around the wafer W is clamped and fixed from four directions by each clamp portion 91. The injection port of the laser processing means 72 is positioned on the division line L of the wafer W, and the laser beam is applied to the tape 80 attached to the wafer W. The laser beam has a wavelength that is absorptive with respect to the tape 80 and is adjusted so as to be condensed inside the tape 80. Then, the irradiation position of the laser beam is moved along the outer edge shape of the device D in a state where the laser beam is irradiated on the tape 80. Thereby, as shown in FIG. 3B, a cutout groove M surrounding the device D is formed along the planned division line L.

  As shown in FIG. 4, after the cut groove processing step, a mask forming step is performed by peeling the tape 80 along the cut groove M in a peeling device. As shown in FIG. 4A, the wafer W is supported by the ring frame F via the protective tape T, and is sucked and held by the holding table 63 via the protective tape T. Above the holding table 63, a gripping means 73 connected to the moving means 74 is provided. The gripping means 73 clamps the end of the tape 80 with the clamping part 73a. In this state, the moving means 74 is raised in the Z-axis direction by the elevating means 75 and moved in the horizontal direction with respect to the holding table 63, whereby the gripping means 73 is moved from one end to the other end of the outer periphery of the wafer W. Roll up tape 80 toward you. At this time, as shown in FIG. 8, the tape 80 is peeled off in a mesh shape, and as shown in FIG. 4B, the tape 80 is left on the surface of the device D, and the division line L is exposed to the outside. Thereby, the tape 80 left on the surface of the device D can be used as a mask in the subsequent plasma etching process.

  The tape 80 is attached to the wafer W, and the cut groove M is formed so as to surround the device D by the laser processing means 72, so that the tape 80 corresponding to the division line L is peeled integrally along the cut groove M. The tape 80 that can be used and remains on the surface of the device D can be used as a mask. Accordingly, it is not necessary to use a solvent used when developing a conventional photoresist film, and thus a mask can be easily formed.

  After the mask formation step, a plasma etching step is performed in the plasma etching apparatus. First, before describing the plasma etching process, a plasma etching apparatus used in the plasma etching process will be described. FIG. 9 is an overall schematic diagram of the plasma etching apparatus according to the present embodiment.

  As shown in FIG. 9, a loading / unloading port 13 is formed on the side wall 12 of the chamber 11 of the plasma etching apparatus 1 for loading and unloading the wafer W. A shutter mechanism 21 is attached to the outer wall surface of the side wall 12 so as to open and close the loading / unloading port 13. In the shutter mechanism 21, a shutter 23 is connected to the upper end of a cylinder 22, and the carry-in / out port 13 is opened and closed by the cylinder 22 being moved up and down along the outer wall surface. When the loading / unloading port 13 is closed by the shutter 23, a sealed space is formed in the chamber 11. In the chamber 11, a lower electrode unit 31 and an upper electrode unit 41 that form an electric field are disposed facing each other in the vertical direction.

  The lower electrode unit 31 is provided on the upper end of a conductive support 32 that penetrates the bottom wall 14 of the chamber 11. The lower electrode unit 31 is configured by attaching a disc-shaped holding plate 34 made of a porous material to the upper surface of a conductive holding table 33. The holding plate 34 is connected to a suction source 36 through a holding table 33 and a suction path 35 in the support column 32. In the lower electrode unit 31, a cooling path 38 through which the cooling water sent out from the cooling unit 37 passes is formed. At the time of etching, heat generated in the holding table 33 is transmitted to the cooling water, and an abnormal temperature rise is suppressed.

  The upper electrode unit 41 is provided at the lower end of the conductive support column 42 that penetrates the upper wall 15 of the chamber 11. The upper electrode unit 41 is configured by attaching a disc-shaped diffusion plate material 44 formed of a porous material to the lower surface of a conductive ejection table 43 for introducing an etching gas into the chamber 11. The diffusion plate 44 is connected to the etching gas source 48 through the ejection table 43 and the flow path 45 in the support column 42.

An etching gas such as sulfur hexafluoride (SF ₆ ), tetrafluoromethane (CF ₄ ), and nitrogen trifluoride (NF ₃ ) is supplied into the chamber 11 from an etching gas source 48. Further, the upper end side of the support column 42 protrudes upward from the chamber 11 and is connected to a ball screw type elevating drive mechanism 49 provided on the upper wall 15 of the chamber 11. By driving the elevating drive mechanism 49, the upper electrode unit 41 is moved away from or approached to the lower electrode unit 31, and the height of the ejection table 43 with respect to the silicon wafer W on the holding table 33 is an appropriate position. Adjusted to

  By applying a high frequency voltage between the lower electrode unit 31 and the upper electrode unit 41, the etching gas is turned into plasma. Furthermore, a discharge port 53 is formed in the chamber 11 below the holding table 33, and a pressure reducing unit 54 is connected to the discharge port 53. The air and the etching gas in the chamber 11 are sucked by the decompression unit 54, and the pressure is reduced until the inside of the chamber 11 is in a negative pressure state.

  In the etching apparatus 1 configured as described above, an etching gas is jetted from the upper electrode unit 41 toward the wafer W in a state where the inside of the chamber 11 is at a negative pressure. In this state, the wafer W is plasma etched by applying a high frequency voltage between the upper electrode unit 41 and the lower electrode unit 31.

  The wafer W (see FIG. 4B) in which the tape 80 is left on the surface of the device D is carried into the chamber 12. The wafer W is supported by the ring frame F via the protective tape T and is sucked and held by the holding table 33 via the protective tape T. The shutter 23 is closed and the upper electrode unit 41 is moved closer to the lower electrode unit 31 to adjust the distance between the electrodes. When the decompression process is started by the decompression unit 54 until the pressure in the chamber 12 becomes a negative pressure state, the coolant is passed through the cooling path 38 and the holding table 33 is cooled by the coolant.

  Etching gas is injected from the upper electrode unit 41 in this reduced pressure state. A high-frequency voltage is applied from the high-frequency power source 42 between the upper electrode unit 41 and the lower electrode unit 33 to supply high-frequency power, and the etching gas is turned into plasma (radicalized). Only the portion other than the device D masked by the tape 80 on the surface of the wafer W, that is, only the division planned line, is plasma etched by the plasma etching gas. Then, as shown in FIG. 5, the division lines G penetrate in the vertical direction and the division grooves G are formed along the division lines, so that the wafer W is divided into individual devices D.

  When the plasma etching of the wafer W is completed, the application of the high frequency voltage from the high frequency power source 51 to the upper electrode unit 41 and the lower electrode unit 31 is stopped, and the supply of the high frequency power is stopped. Further, the injection of etching gas from the upper electrode unit 41 is stopped, and the upper electrode unit 41 is separated from the lower electrode unit 31. The decompression process by the decompression unit 54 is finished, and the flow of the cooling water to the cooling path 38 is stopped. The shutter 23 is opened, and the device into which the wafer W is divided is carried out of the chamber 11.

  As shown in FIG. 6, a peeling tape sticking process is implemented in a tape sticking apparatus after a plasma etching process. The wafer W is supported by the ring frame F via the protective tape T, and is sucked and held by the holding table 64 via the protective tape T. A pressure roller 76 is provided above the holding table 64, and the pressure roller 76 uses the adhesive layer 87 side of the peeling tape 85 made of the base material 86 and the adhesive layer 87 as a mask attached to the surface of the device D. It is pressed against the used tape 80 and attached.

  As shown in FIG. 7, after the peeling tape attaching process, a mask removing process is performed in the peeling apparatus. The wafer W is supported by the ring frame F via the protective tape T, and is sucked and held by the holding table 65 via the protective tape T. A gripping means 77 provided above the holding table 65 holds the end portion of the peeling tape 85 with the holding portion 77a. In this state, the moving means 78 is lifted in the Z-axis direction by the elevating means 79 and moved in the horizontal direction with respect to the holding table 65, whereby the gripping means 77 is moved from one end to the other end of the outer periphery of the wafer W. The release tape 85 is peeled off. Thereby, the tape 80 to which the adhesive layer 87 of the peeling tape 85 is stuck is peeled off together with the peeling tape 85, and the tape 80 as a mask is removed from the surface of the device D. As the peeling tape 85, for example, a tape having an adhesive strength equal to or greater than the adhesive strength of the tape glue layer 82 of the tape 80 remaining on the surface of the device D may be used.

  Since the tape 80 is adhered to the wafer W with the tape adhesive layer 82, it can be easily peeled off. Therefore, it is not necessary to perform ashing in order to remove the photoresist film, and the device D is not adversely affected by heat. Further, since it is not necessary to perform wet peeling unlike a photoresist film, it can be performed in a dry environment. Thus, the tape 80 as a mask can be easily removed.

  As described above, in the mask forming method and the wafer W processing method according to the present embodiment, the tape 80 is attached to the wafer W, the cut groove is formed in the tape 80 by laser processing, and the cut groove M is aligned. Thus, the tape 80 left on the surface of the wafer W can be used as a mask by peeling the tape 80 together. Thus, a mask can be formed more easily than a conventional structure in which a photoresist film is coated and exposed, and further developed to form a mask. Since the tape 80 is adhered to the wafer W with the adhesive layer 82, the mask can be easily removed by peeling. Further, when removing the tape 80, it is not necessary to perform the wet stripping performed by the conventional photoresist film, so that it can be performed in a dry environment, and since it is not necessary to perform ashing, the device D is not adversely affected by heat. .

  In the above embodiment, a dicing tape is used as the tape 80, but a BG tape for protecting the device D can be used as the tape 80. Thereby, the device D can be protected and the BG tape can be used as a mask for plasma etching.

  Moreover, in the said embodiment, although it was set as the structure which uses the tape 80 as a mask for plasma etching by forming the cut-out groove | channel M in the tape 80 and leaving it on the surface of the device D, it is not limited to this. The tape 80 can also be used for selectively irradiating light as a photomask for the photoresist film.

  Moreover, in the said embodiment, although it was set as the structure in which the peeling tape sticking process and a mask removal process were included in the division | segmentation method of a wafer, it is good also as a structure from which a peeling tape sticking process and a mask removal process are not included.

  The embodiments of the present invention are not limited to the above-described embodiments, and various changes, substitutions, and modifications may be made without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in another way by technological advancement or another derived technique, the method may be used. Accordingly, the claims cover all embodiments that can be included within the scope of the technical idea of the present invention.

  In this embodiment mode, a structure in which the present invention is applied to a mask formation method and a wafer processing method has been described. However, the present invention can also be applied to other processing methods for selectively plasma etching a substrate.

  As described above, the present invention has an effect that a mask for etching can be easily manufactured, and in particular, a method of forming a mask for etching and a wafer that is divided by etching using the mask. Useful for processing methods.

80 Tape G Dividing groove M Cutout groove D Device L Divided line W Wafer

Claims (2)

A method for forming a mask, comprising:
A tape sticking process for sticking the tape to the wafer;
A cut groove processing step of forming a cut groove on the tape by irradiating a laser beam having an absorptive wavelength to the tape attached in the tape attaching step;
A mask forming method comprising: a step of peeling the tape along the cut groove processed in the cut groove processing step, and a mask forming step in which the tape left on the wafer without being peeled becomes a mask. A wafer processing method of dividing a wafer by masking the device of the wafer partitioned by the planned dividing line and forming a plurality of devices, and dry etching the planned dividing line,
A tape sticking process for sticking the tape to the wafer;
A cut groove processing step in which a laser beam having an absorptive wavelength is applied to the tape attached to the wafer in the tape attaching step, and a cut groove is formed in the tape along the planned dividing line;
A mask forming step in which the tape is peeled along the cut groove processed in the cut groove processing step, and the tape left on the surface of the wafer device without being peeled is used as a mask;
A plasma etching step of plasma-etching the wafer masked with the device in the mask formation step to form a division groove along the division line.

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