JP2018036569A - Production method of photomask for wafer processing - Google Patents

Abstract

[Problem] To provide a method for manufacturing a photomask for wafer processing, which can inexpensively and easily manufacture a photomask that can be patterned as designed. [Solution] The method for manufacturing a photomask for wafer processing includes a preparation step ST1 for preparing a light-transmitting plate that is larger than the wafer to be processed and transmits light, a recess formation step ST2 for irradiating the front side of the light-transmitting plate in the area to be shielded with laser light to form a recess that is deep enough not to reach the back side of the light-transmitting plate, a light-shielding material embedding step ST3 for embedding a light-shielding material that shields light in the recess after the recess formation step ST2, and a thinning step ST4 for holding the back side of the light-transmitting plate and thinning the light-transmitting plate together with the light-shielding material embedded from the front side to a predetermined thickness. [Selected Figure] Figure 5

Description

  The present invention relates to a method of manufacturing a photomask for wafer processing used when a wafer is divided into devices by plasma etching.

  A semiconductor wafer formed on the surface by dividing a plurality of devices such as IC (Integrated Circuit), LSI (Large-Scale Integration), etc. by dividing lines is ground and then processed to a predetermined thickness, followed by dicing It is divided into individual devices by an apparatus and a laser processing apparatus, and the divided devices are widely used in various electronic devices such as mobile phones and personal computers.

  However, at the time of dicing by the dicing apparatus, the cutting blade that rotates at a high speed cuts into the division line of the wafer. Therefore, the device is chipped due to the crushing force of the cutting blade, and the bending strength of the device is lowered. Therefore, in order to improve the bending strength of the device, a technique has been proposed in which the division line of the wafer is divided into individual devices by plasma etching. For example, Patent Document 1 proposes a method for manufacturing a photomask used for plasma etching.

  The manufacturing method disclosed in Patent Document 1 can easily create a photomask. Specifically, the manufacturing method disclosed in Patent Document 1 forms a groove having a depth that does not reach the back surface of the transparent plate in a region on the front surface side corresponding to the street of the wafer to be processed of the transparent plate. Then, a light shielding material having a light shielding property is embedded in the groove to form a photomask.

Japanese Patent Laid-Open No. 2006-18139

  However, as disclosed in Patent Document 1, when a groove is formed by cutting with a cutting blade or a groove is formed by irradiating a laser beam, a recess is formed on the upper part of the groove side wall on the surface side of the transparent plate. Chipping of about several microns may occur on the upper side wall, or debris generated by laser processing may be generated and attached to the device surface. As a result, the manufacturing method disclosed in Patent Document 1 has a problem that when the processed wafer is exposed, these irregular shapes are transferred to the resist in the exposure, and cannot be patterned as designed.

  The present invention has been made in view of these points, and an object of the present invention is to provide a method of manufacturing a photomask for wafer processing that can accurately manufacture a photomask that can be patterned as designed at a low cost. It is.

  In order to solve the above-described problems and achieve the object, the method for manufacturing a photomask for wafer processing according to the present invention is a method for manufacturing a photomask for wafer processing, and has a size larger than the wafer to be processed. A preparation step of preparing a light-transmitting plate that transmits light, and a recess having a depth that does not reach the back surface of the light-transmitting plate by irradiating laser light onto the surface side of the light-transmitting plate in a region where light should be shielded A recessed portion forming step to be formed, a light shielding material embedding step for embedding a light shielding material for shielding light in the recessed portion after the recessed portion forming step, and a back surface side of the translucent plate, and embedded from the front surface side. In addition, a thinning step of thinning the translucent plate to a predetermined thickness together with the light shielding material is provided.

  According to the present invention, debris adhering to the surface of the light transmissive plate in the recess forming step can be removed together with the light shielding material in the thinning step, so that it is not necessary to cover the surface of the light transmissive plate with a protective film for ablation processing. As a result, the photomask that can be patterned as designed can be manufactured accurately at a low cost.

FIG. 1 is a perspective view showing a wafer to be processed by the wafer processing photomask according to the first embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is a perspective view showing the wafer processing photomask according to the first embodiment. 4 is a cross-sectional view of a main part of the photomask for wafer processing shown in FIG. FIG. 5 is a flowchart showing a flow of a method of manufacturing a photomask for wafer processing according to the first embodiment. FIG. 6 is a cross-sectional view illustrating a preparation process of the method for manufacturing the photomask for wafer processing shown in FIG. FIG. 7 is a cross-sectional view showing a recess forming step in the method of manufacturing the photomask for wafer processing shown in FIG. FIG. 8 is a cross-sectional view of the main part of the translucent plate after the recess forming step of the method for manufacturing the photomask for wafer processing shown in FIG. FIG. 9 is a plan view of the main part of the translucent plate after the recess forming step of the method for manufacturing the photomask for wafer processing shown in FIG. FIG. 10 is a cross-sectional view showing a light shielding material embedding step of the method for manufacturing the wafer processing photomask shown in FIG. FIG. 11 is a cross-sectional view of the thinning process of the method of manufacturing the photomask for wafer processing shown in FIG. FIG. 12 is a cross-sectional view showing a resist coating process of a method for forming a protective film on a wafer using the wafer processing photomask shown in FIG. FIG. 13 is a cross-sectional view showing an exposure process of a method for forming a protective film on a wafer using the wafer processing photomask shown in FIG. FIG. 14 is a sectional view of a wafer on which a protective film is formed using the wafer processing photomask shown in FIG. FIG. 15 is a plan view of a part of a wafer of another example to be processed by the wafer processing photomask according to the first embodiment. FIG. 16 is a plan view of a part of a wafer of still another example of a processing target of the photomask for wafer processing according to the first embodiment. FIG. 17 is a flowchart showing a flow of a method of manufacturing a photomask for wafer processing according to the second embodiment. FIG. 18 is a cross-sectional view showing a light-transmitting plate thinning step in the method for manufacturing the wafer processing photomask shown in FIG. FIG. 19 is a cross-sectional view of the light transmissive plate after the light transmissive plate thinning step of the method for manufacturing the wafer processing photomask shown in FIG. 17. FIG. 20 is a cross-sectional view showing a light shielding material embedding step of the method for manufacturing the wafer processing photomask shown in FIG. FIG. 21 is a cross-sectional view showing a light shielding material thinning step of the method for manufacturing the wafer processing photomask shown in FIG. FIG. 22 is a cross-sectional view showing a light shielding material embedding step of the method for manufacturing a wafer processing photomask according to a modification of the first embodiment. FIG. 23 is a perspective view of a wafer processing photomask manufactured by the method of manufacturing a wafer processing photomask according to a modification of each embodiment. FIG. 24 is a cross-sectional view of a main part of the wafer processing photomask shown in FIG. FIG. 25 is a perspective view showing a recess forming step in the method for manufacturing a photomask for wafer processing of the disclosed example. FIG. 26 is a cross-sectional view of the main part of the light-transmitting plate after the recess forming step of the method for manufacturing the photomask for wafer processing according to the disclosed example. FIG. 27 is an enlarged cross-sectional view of the XXVII portion in FIG. FIG. 28 is a cross-sectional view showing a light shielding material embedding step of the method for manufacturing a wafer processing photomask of the disclosed example. FIG. 29 is a cross-sectional view of a main part of a wafer processing photomask manufactured by the method for manufacturing a wafer processing photomask of the disclosed example.

  DESCRIPTION OF EMBODIMENTS 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 contents described in the following embodiments. 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 structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

Embodiment 1
A method of manufacturing a photomask for wafer processing according to Embodiment 1 will be described with reference to the drawings. FIG. 1 is a perspective view showing a wafer to be processed by the wafer processing photomask according to the first embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is a perspective view showing the wafer processing photomask according to the first embodiment. 4 is a cross-sectional view of a main part of the photomask for wafer processing shown in FIG.

  The wafer processing photomask manufacturing method according to the first embodiment is a method of manufacturing the wafer processing photomask 1 shown in FIGS. 3 and 4 used when processing the wafer W shown in FIGS. 1 and 2. . The wafer W shown in FIGS. 1 and 2 is a disk-shaped semiconductor wafer or optical wafer having a substrate S of silicon, sapphire, gallium arsenide or the like in the first embodiment. As shown in FIGS. 1 and 2, the wafer W has devices D formed in each region on the substrate S defined by a plurality of division lines L intersecting the surface WS (in the first embodiment, orthogonal). ing. The wafer W according to the first embodiment includes a rectangular device D having a width of a predetermined division line L of about several tens of μm or less and a size of 0.1 mm or more and 20 mm or less on one side. The device D is preferably divided. Further, the thickness of the wafer W according to the first embodiment is not less than 30 μm and not more than 300 μm. Further, in the first embodiment, the device D of the wafer W is formed in a quadrangular planar shape and is equal in size to each other. However, the present invention is not limited to this, and the device D having various sizes on the surface WS of the wafer W. The planar shape may be an irregular shape other than a quadrangle.

  The wafer processing photomask 1 performs plasma etching on the wafer W, and forms a protective film P (shown in FIG. 14) on the wafer W used for processing to divide the wafer W into individual devices D by plasma etching. Is. The protective film P is composed of a resist R (shown in FIGS. 12 and 13).

  As shown in FIGS. 3 and 4, the wafer processing photomask 1 includes a translucent plate 2. The light transmissive plate 2 transmits light irradiated to the resist R when the resist R is exposed. The translucent plate 2 has a size larger than the wafer W to be processed. In the first embodiment, the translucent plate 2 is formed in a disk shape having substantially the same size as the wafer W. In the first embodiment, the translucent plate 2 is made of quartz glass.

  The light-transmitting plate 2 is provided with a light blocking unit 3 that blocks light applied to the resist R when the resist R applied to the surface WS of the wafer W is exposed. In the first embodiment, the light blocking unit 3 is provided at a position that overlaps the division line L when the wafer processing photomask 1 is overlaid on the wafer W coated with the resist R. In the first embodiment, the light blocking unit 3 is formed in the same planar shape as the planned division line L, that is, in the same width and length.

  The light blocking portion 3 is configured by a concave portion 4 formed in a concave shape from the surface 2S of the translucent plate 2 and a light shielding material 5 filled in the concave portion 4. The light shielding material 5 blocks light applied to the resist R when the resist R is exposed. The light shielding material 5 is composed of nano ink that shields light for exposing the resist R. The nano ink is obtained by dispersing metal nanoparticles such as Ag (silver) of several nm to several tens of nm in a liquid. In the first embodiment, the light shielding material 5 is composed of nano ink, but the present invention is not limited to this, and may be composed of various materials that shield light.

  Next, a method for manufacturing a photomask for wafer processing according to Embodiment 1 will be described with reference to the drawings. FIG. 5 is a flowchart showing a flow of a method of manufacturing a photomask for wafer processing according to the first embodiment. FIG. 6 is a cross-sectional view illustrating a preparation process of the method for manufacturing the photomask for wafer processing shown in FIG. FIG. 7 is a cross-sectional view showing a recess forming step in the method of manufacturing the photomask for wafer processing shown in FIG. FIG. 8 is a cross-sectional view of the main part of the translucent plate after the recess forming step of the method for manufacturing the photomask for wafer processing shown in FIG. FIG. 9 is a plan view of the main part of the translucent plate after the recess forming step of the method for manufacturing the photomask for wafer processing shown in FIG. FIG. 10 is a cross-sectional view showing a light shielding material embedding step of the method for manufacturing the wafer processing photomask shown in FIG. FIG. 11 is a cross-sectional view of the thinning process of the method of manufacturing the photomask for wafer processing shown in FIG.

  The wafer processing photomask manufacturing method (hereinafter simply referred to as manufacturing method) according to Embodiment 1 is a method of manufacturing the wafer processing photomask 1 (hereinafter simply referred to as photomask) shown in FIG.

  As shown in FIG. 5, the manufacturing method includes a preparation step ST1, a recess forming step ST2, a light shielding material embedding step ST3, and a thinning step ST4.

  As shown in FIG. 6, the preparation step ST <b> 1 is a step of preparing a translucent plate 2 </ b> A in which the light blocking part 3 is not formed. The translucent plate 2A has the same configuration as the translucent plate 2 except that the light blocking portion 3 is not formed and is not thinned. Is omitted. The thickness T of the translucent plate 2A is thicker than the thickness TM of the photomask 1, and is 700 μm in the first embodiment.

In the recess forming step ST2, the surface 2S of the translucent plate 2A is irradiated by irradiating the surface 2S of the translucent plate 2A in the region where light is to be shielded with a laser beam LR having a wavelength that absorbs the translucent plate 2A. This is a step of forming a recess 4 having a depth DP that does not reach the back surface 2R on the back side. In the recess forming step ST2, the back surface 2R side of the translucent plate 2A is sucked and held on the chuck table 101 of the laser processing machine 100, and the light of the translucent plate 2A is emitted when the photomask 1 is overlaid on the wafer W for exposure. The laser beam LR is irradiated from the laser irradiation unit 102 to the region RL shown in FIG. 7 that overlaps the planned division line L that is the region to be shielded, and the translucent plate 2A is ablated. In the first embodiment, the recess forming step ST2 moves the chuck table 101 and the laser irradiation unit 102 of the laser processing machine 100 relative to each other along the processing feed direction X and the index feed direction Y, thereby dividing each divided line. As shown in FIG. 7, the laser beam LR is irradiated on the region RL that overlaps L. In the first embodiment, the recess forming step ST2 is a region where the translucent plate 2A is irradiated with a laser beam LR having a wavelength of about 10 μm, for example, and subjected to ablation processing, and as shown in FIG. A recess 4 is formed in the RL. In the first embodiment, for example, a CO ₂ (carbon dioxide) laser can be used as the laser light LR.

  As shown in FIGS. 8 and 9, the translucent plate 2 </ b> A after the recess forming step ST <b> 2 is formed with the recess 4 along the planned division line L, and fine dust that is generated and scattered during ablation processing. The debris DB constituted by is attached to the surface 2S. In addition, the translucent plate 2A after the recess forming step ST2 has the debris DB attached to the edge portion of the inner surface 4a of the recess 4 near the surface 2S, and the irregularly shaped portion PL is formed. The irregularly shaped portion PL is a portion where irregularities finer than the flat surface near the bottom surface 4b of the inner surface 4a of the recess 4 are formed. In the first embodiment, the range AR is 3 μm from the surface 2S of the inner surface 4a of the recess 4. Is formed inside.

  In Embodiment 1, the thickness T of the translucent plate 2A before the light blocking portion 3 is formed is about 0.7 mm or more, and the range AR in which the irregularly shaped portion PL is formed is 3 μm from the surface 2S. Within the range, the depth DP of the recess 4 is about 10 μm.

  The light shielding material embedding step ST3 is a step of embedding a light shielding material 5 for blocking light in the concave portion 4 after the concave portion forming step ST2. In the first embodiment, in the light shielding material embedding step ST3, the rear surface 2R on the back side of the front surface 2S of the translucent plate 2A is held by a spinner (not shown), and the translucent plate 2A is rotated around the axis by the spinner. As shown in FIG. 10, the light shielding material 5 is embedded in the recess 4 and covered with the entire surface 2S of the translucent plate 2A, and the light shielding material 5 is cured. . In the first embodiment, in the light shielding material embedding process ST3, the light shielding material 5 is coated on the surface 2S of the light transmissive plate 2A by a spinner. In the present invention, the light shielding material 5 is supplied from the inkjet nozzle to the surface 2S of the light transmissive plate 2A. Then, the light shielding material 5 may be covered on the surface 2S of the light transmitting plate 2A. In the light shielding material embedding process ST3 of the manufacturing method according to the first embodiment, the depth at which the thickness of the light blocking part 3 that can provide the contrast necessary for the exposure of the resist R in the photomask 1 that has undergone the thinning process ST4 described later can be ensured. A recess 4 of depth DP is formed, and a light shielding material 5 is embedded in the recess 4.

  In the thinning step ST4, after the light shielding material embedding step ST3 is performed, the light transmitting plate 2A is held together with the light shielding material 5 embedded from the front surface 2S side of the light transmitting plate 2A while holding the back surface 2R side of the light transmitting plate 2A. This is a step of thinning the photomask 1 to a predetermined thickness TM. In Embodiment 1, the thickness TM of the photomask 1 is smaller than the value obtained by subtracting the range AR from the thickness T of the light transmitting plate 2A before the thinning step ST4. For this reason, in the thinning step ST4, the light-transmitting plate 2A together with the light shielding material 5 is ground and removed from the front surface 2S side to a position closer to the back surface 2R than the range AR. In the first embodiment, the range AR in which the irregularly shaped portion PL is formed is within a range of 3 μm (about 1/10 of the planned division line L) from the surface 2S, and the thickness TJ of the translucent plate 2A to be ground and removed is The thickness T of the translucent plate 2A is within a range where the strength of the photomask 1 of about 0.7 mm to 10 mm can be obtained. In the thinning step ST4, as shown in FIG. 11, the back surface 2R side of the light-transmitting plate 2A is sucked and held by the chuck table 201 of the grinding device 200, and the grinding wheel 202 of the grinding wheel 203 is pushed onto the surface 5S of the light shielding material 5. Then, the chuck table 201 and the grinding wheel 203 are rotated about the axis, and the light-transmitting plate 2A is ground together with the light shielding material 5 by the grinding wheel 202 to the thickness TM of the photomask 1 which is a predetermined thickness. When the translucent plate 2A reaches the thickness TM of the photomask 1, the irregularly shaped portion PL is removed from the inner surface 4a of the recess 4 and the translucent plate 2A is formed on the translucent plate 2. In the thinning step ST4, after grinding with the grinding wheel 202, the surface 2S of the translucent plate 2 is used by using a surface planer, a polishing apparatus or a CMP (Chemical Mechanical Polishing) polishing apparatus until the arithmetic surface roughness Ra becomes about 10 nm. The surface 5S of the light shielding material 5 is polished or CMPed. In this way, the photomask 1 is obtained.

  Next, a method for forming the protective film P of the wafer W using the photomask 1 manufactured by the manufacturing method according to the first embodiment will be described with reference to the drawings. FIG. 12 is a cross-sectional view showing a resist coating process of a method for forming a protective film on a wafer using the wafer processing photomask shown in FIG. FIG. 13 is a cross-sectional view showing an exposure process of a method for forming a protective film on a wafer using the wafer processing photomask shown in FIG. FIG. 14 is a sectional view of a wafer on which a protective film is formed using the wafer processing photomask shown in FIG.

  The method for forming the protective film P on the wafer W using the photomask 1 manufactured by the manufacturing method according to the first embodiment includes the resist coating process shown in FIG. 12 and the exposure process shown in FIG. In the resist coating step, the back surface WR on the back side of the front surface WS of the wafer W is held by a spinner (not shown), and the resist R is supplied to the front surface WS of the wafer W while rotating the wafer W around the axis by the spinner. As shown in FIG. 2, a resist R is applied to the surface WS of the wafer W in the form of a thin film. The resist R according to the first embodiment is a so-called negative resist in which an exposed portion remains on the surface WS of the wafer W.

  In the exposure step, the wafer W and the photomask 1 are positioned in a state where the light shielding material 5 faces the surface WS of the wafer W and the light blocking portion 3 faces the division line L. In the exposure process, the resist R applied to the wafer W is irradiated with light through the photomask 1 to be exposed. Then, since the light blocking part 3 faces the division planned line L, the light is irradiated onto the part of the resist R that overlaps the device D. When the resist R is developed, a protective film P such as a resist mask composed of the resist R remains on the device D as shown in FIG. As shown in FIG. 14, the wafer W in which the device D is covered with the protective film P is divided into individual devices D by cutting the substrate S of the line L to be divided by plasma etching.

  In the manufacturing method according to the first embodiment, the debris DB attached to the surface 2S of the translucent plate 2A and the inner surface 4a of the recess 4 in the recess forming step ST2 is removed together with the light shielding material 5 in the thinning step ST4. For this reason, the manufacturing method is produced by ablation without covering the surface 2S of the translucent plate 2A with a protective film for ablation before forming the recess 4 using the laser beam LR in the recess forming step ST2. The debris DB, that is, the irregularly shaped portion PL generated on the inner surface 4a of the concave portion 4 can be removed. As a result, the manufacturing method can achieve cost reduction and simplification of the manufacturing process, can be thinned by grinding, and can remove the irregularly shaped portion PL, so that the photomask 1 that can be patterned as designed can be obtained. It can be manufactured more accurately at a low cost. In the manufacturing method according to the first embodiment, the laser beam LR is irradiated onto the light transmitting plate 2A to form the concave portion 4 that constitutes the light blocking portion 3, so that the wafer W on which devices D of various sizes are formed is formed. The photomask 1 that can also be used for the processing can be easily manufactured.

  Further, the manufacturing method according to the first embodiment is a street that does not form a straight line continuous from one end to the other end because the concave portion 4 constituting the light blocking portion 3 is formed by irradiating the light transmitting plate 2A with the laser beam LR. The photomask 1 that can be used to divide the wafers W ′ and W ″ illustrated in FIGS. 15 and 16 that are the workpieces to which the division lines L are set can be easily manufactured.

  Note that the wafer W ′, which is a workpiece on which a division line L that is a street that does not form a straight line from one end to the other end, is set, as illustrated in FIG. A device in which a different device D ′ is formed is included. The wafer W ′ shown in FIG. 15 is used for, for example, research purposes or trial manufacture. In addition, as the wafer W ′ that is the workpiece on which the division line L that is a street that does not become a straight line that continues from one end to the other end is set, the division line L that does not become a straight line that continues from one end to the other end. , Devices in which devices D of the same size are arranged, and devices in which devices D of a plurality of shapes (for example, a rectangle and a circle) are mixedly mounted are included.

  In addition, as shown in FIG. 16, the wafer W ″ that is a workpiece on which a division line L that is a street that is not a straight line continuous from one end to the other end has an irregular shape other than a square as illustrated in FIG. In which the device D ″ is formed. In the wafer W ″ shown in FIG. 16, for example, the planar shape of the device D ″ is formed in a honeycomb shape (hexagon). Further, the planar shape of the irregularly shaped device D ″ is not limited to the honeycomb shape, and may be various shapes such as a circle. FIG. 15 is a plan view of a part of a wafer of another example to be processed by the wafer processing photomask according to the first embodiment. FIG. 16 is a plan view of a part of a wafer of still another example of a processing target of the photomask for wafer processing according to the first embodiment.

  Further, in the photomask 1 manufactured by the manufacturing method according to the first embodiment, since the concave portion 4 constituting the light blocking portion 3 is configured by irradiating the light transmitting plate 2A with the laser beam LR, the concave portion 4 is formed on the wafer. A shape corresponding to the division line L of W, that is, a shape equivalent to the division line L can be formed. For this reason, the photomask 1 uses a negative resist R which is cheaper than a positive resist in which the exposed portion is removed from the surface WS of the wafer W when the resist R is formed on the wafer W. Since the protective film P made of the resist R can be formed on the device D, the cost for processing the wafer W and manufacturing the device D can be reduced.

[Embodiment 2]
A method of manufacturing a photomask for wafer processing according to Embodiment 2 will be described with reference to the drawings. FIG. 17 is a flowchart showing a flow of a method of manufacturing a photomask for wafer processing according to the second embodiment. FIG. 18 is a cross-sectional view showing a light-transmitting plate thinning step in the method for manufacturing the wafer processing photomask shown in FIG. FIG. 19 is a cross-sectional view of the light transmissive plate after the light transmissive plate thinning step of the method for manufacturing the wafer processing photomask shown in FIG. 17. FIG. 20 is a cross-sectional view showing a light shielding material embedding step of the method for manufacturing the wafer processing photomask shown in FIG. FIG. 21 is a cross-sectional view showing a light shielding material thinning step of the method for manufacturing the wafer processing photomask shown in FIG. In the second embodiment, the same parts as those in the first embodiment will be described with the same reference numerals.

  A method for manufacturing a photomask for wafer processing according to the second embodiment (hereinafter simply referred to as a manufacturing method) is a method for manufacturing the same photomask 1 as in the first embodiment. As shown in FIG. 17, the manufacturing method includes a preparation step ST1, a recess forming step ST2, a translucent plate thinning step ST5, a light shielding material embedding step ST13, and a light shielding material thinning step ST14.

  The preparation step ST1 and the recess formation step ST2 are the same as those in the first embodiment. The light-transmitting plate thinning step ST5 is a step of forming the light-transmitting plate 2A to the thickness TM of the photomask 1 having a predetermined thickness and forming the light-transmitting plate 2 after the recess forming step ST2. In the translucent plate thinning step ST5, as shown in FIG. 18, the back surface 2R side of the translucent plate 2A is sucked and held by the chuck table 201 of the grinding device 200, and the grinding wheel 203 is ground on the front surface 2S of the translucent plate 2A. The grindstone 202 is pressed, the chuck table 201 and the grinding wheel 203 are rotated around the axis, and the translucent plate 2A is ground by the grinding grindstone 202 to the thickness TM of the photomask 1 which is a predetermined thickness. When the translucent plate 2A reaches the thickness TM of the photomask 1, the irregularly shaped portion PL is removed from the inner surface 4a of the recess 4.

  The light shielding material embedding step ST13 is a step of embedding the light shielding material 5 for blocking light in the concave portion 4 after the light transmitting plate thinning step ST5, that is, after the concave portion forming step ST2. In the second embodiment, in the light shielding material embedding step ST13, as in the light shielding material embedding step ST3 of the first embodiment, the rear surface 2R of the light transmissive plate 2 is held by a spinner (not shown), and the light transmissive plate 2 is rotated around the axis by the spinner. The light shielding material 5 is supplied to the surface 2S of the translucent plate 2 while being rotated, and the light shielding material 5 is embedded in the recess 4 as shown in FIG. 20, and the entire surface 2S of the translucent plate 2 is covered. Then, the light shielding material 5 is cured. In the second embodiment, the light shielding material embedding step ST13 supplies the light shielding material 5 to the surface 2S of the light transmissive plate 2 from the inkjet nozzle, and the light shielding material 5 is applied to the surface 2S of the light transmissive plate 2 as in the first embodiment. It may be covered.

  In the light shielding material thinning step ST14, after the light shielding material embedding step ST13, the light transmitting plate 2 whose surface 2S is covered with the light shielding material 5 is thinned to the thickness TM of the photomask 1 having a predetermined thickness, and the light transmitting plate This is a step of exposing the surface 2S of the second. In the light shielding material thinning step ST14, as shown in FIG. 21, the rear surface 2R side of the light transmitting plate 2 is sucked and held by the chuck table 201 of the grinding device 200, and the grinding wheel 202 of the grinding wheel 203 is placed on the surface 5S of the light shielding material 5. , The chuck table 201 and the grinding wheel 203 are rotated around the axis, and the light shielding material 5 is ground by the grinding wheel 202 to the thickness TM of the photomask 1 which is a predetermined thickness.

  When the translucent plate 2 with the light shielding material 5 coated on the surface 2S reaches the thickness TM of the photomask 1, the surface 2S of the translucent plate 2 is exposed, and the light blocking portion 3 is formed on the surface 2S of the translucent plate 2. It is formed. The light shielding material thinning step ST14 is performed by using a surface planer, a polishing apparatus or a CMP (Chemical Mechanical Polishing) polishing apparatus until the arithmetic surface roughness Ra becomes 10 nm after grinding by the grinding wheel 202. 2S and the surface 5S of the light shielding material 5 are polished or subjected to CMP. In this way, the photomask 1 is obtained. Note that the light-transmitting plate thinning step ST5 and the light-shielding material thinning step ST14 of the manufacturing method according to the second embodiment hold the back surface 2R side of the light-transmitting plates 2 and 2A, and the surface 2S of the light-transmitting plates 2 and 2A. A thinning step ST4 for thinning the light-transmitting plates 2 and 2A together with the light shielding material 5 embedded from the side to the thickness TM of the photomask 1 having a predetermined thickness is configured.

  In the manufacturing method according to the second embodiment, the debris DB attached to the surface 2S of the light transmissive plate 2A and the inner surface 4a of the concave portion 4 in the concave portion forming step ST2 is removed together with the light shielding material 5 in the light transmissive plate thinning step ST5. For this reason, the manufacturing method does not need to cover the surface 2S of the translucent plate 2A with a protective film before forming the recess 4 using the laser beam LR in the recess forming step ST2 as in the first embodiment. Since the irregularly shaped portion PL can be removed, the photomask 1 that can be patterned as designed can be accurately manufactured at low cost. Moreover, since the manufacturing method according to the second embodiment irradiates the light transmitting plate 2A with the laser light LR to form the concave portion 4 that constitutes the light blocking portion 3, as in the first embodiment, the straight line extends from one end to the other end. It is possible to easily manufacture the photomask 1 that can be used for dividing the wafers W ′ and W ″ in which the planned division lines L are not formed. Further, in the photomask 1 manufactured by the manufacturing method according to the second embodiment, since the concave portion 4 constituting the light blocking portion 3 is configured by irradiating the light transmitting plate 2A with the laser beam LR, the concave portion 4 is formed on the wafer. The shape corresponding to the division line L of W, that is, the shape equivalent to the division line L can be formed. Since the photomask 1 can form the protective film P made of the resist R on the device D using a negative resist that is less expensive than the positive resist, the processing of the wafer W and the manufacture of the device D can be performed. Such costs can be reduced.

[Modification]
A method for manufacturing a photomask for wafer processing according to a modification of each embodiment will be described with reference to the drawings. FIG. 22 is a cross-sectional view showing a light shielding material embedding step of the method for manufacturing a wafer processing photomask according to a modification of the first embodiment. FIG. 23 is a perspective view of a wafer processing photomask manufactured by the method of manufacturing a wafer processing photomask according to a modification of each embodiment. FIG. 24 is a cross-sectional view of a main part of the wafer processing photomask shown in FIG. 22 to 24, the same reference numerals are given to the same portions as those in the first and second embodiments, and the description thereof will be omitted.

  In the light shielding material embedding step ST3 of the method for manufacturing a wafer processing photomask according to the modification of the first embodiment, the light shielding material 5 does not cover the surface 2S of the light-transmitting plate 2 as shown in FIG. The light shielding material 5 may be embedded in the recess 4 so that the surface 5S of 5 is located in the above-described range AR, or the light shielding material may be embedded so as to cover the entire surface 2S as in the first embodiment. Good. The manufacturing method of the photomask for wafer processing provided with the light shielding material embedding process ST3 shown in FIG. 22 can be performed without covering the protective film in the recess forming process ST2 as in the first embodiment. The part PL can be removed in the thinning step ST4.

  Further, the wafer processing photomask 1-2 (hereinafter, simply referred to as a photomask) shown in FIGS. 23 and 24 is an area where the light blocking unit 3 corresponds to the device D by the manufacturing method according to the first embodiment, that is, The light blocking portion 3 is formed at a position facing the device D when the resist R is exposed. The photomask 1-2 shown in FIG. 23 and FIG. 24 forms a protective film P on the device D by exposing the resist R on the outer peripheral side of the division line L and the outermost device D during exposure of the resist R. Is to do. That is, the photomask 1-2 shown in FIG. 23 is for forming the protective film P on the device D using the positive resist R from which the exposed portion is removed. In the recess forming step ST2 of the method of manufacturing the photomask 1-2 shown in FIGS. 23 and 24, the recess 4 is formed by irradiating the region corresponding to the device D on the surface 2S of the light transmitting plate 2A with the laser beam LR. In the manufacturing method of the photomask 1-2 shown in FIGS. 23 and 24, the recess 4 is formed by ablation processing using the laser beam LR. Therefore, the recess 4 can be formed in the region corresponding to the device D and is exposed by development. The protective film P made of the resist R can be formed on the device D by using the positive resist R from which the removed portion is removed from the surface WS of the wafer W. The photomask 1-2 shown in FIGS. 23 and 24 is manufactured by irradiating the surface 2S of the translucent plate 2A with the laser beam LR in both the positive resist application and the negative resist application. Therefore, in addition to forming a straight line extending continuously from one end of the wafer W to the other end, the recesses 4 having various shapes can be formed.

[Disclosure Example]
A method of manufacturing a photomask for wafer processing according to a disclosed example will be described with reference to the drawings. FIG. 25 is a perspective view showing a recess forming step in the method for manufacturing a photomask for wafer processing of the disclosed example. FIG. 26 is a cross-sectional view of the main part of the translucent plate after the recess forming step of the manufacturing method of the photomask for wafer processing of the disclosed example. FIG. 27 is an enlarged cross-sectional view of the XXVII portion in FIG. FIG. 28 is a cross-sectional view showing a light shielding material embedding step of the method for manufacturing a wafer processing photomask of the disclosed example. FIG. 29 is a cross-sectional view of a main part of a wafer processing photomask manufactured by the method for manufacturing a wafer processing photomask of the disclosed example. In the disclosure example, the same portions as those in the first embodiment are denoted by the same reference numerals.

  The method for manufacturing a photomask for wafer processing according to the disclosed example (hereinafter simply referred to as a manufacturing method) is a method for manufacturing the same photomask 1 as that of the first embodiment shown in FIG. The manufacturing method according to the disclosed example is the same as the manufacturing method according to the first embodiment, except that the recess forming step ST2 is different from the first embodiment.

  The recess forming step ST2 of the manufacturing method according to the disclosed example is performed by the cutting blade 301 of the cutting device 300 on the region RL that overlaps the division line L at the time of exposure of the resist R that is a region where light to expose the resist R is to be shielded. This is a step of forming the recess 4 having a depth DP that does not reach the back surface 2R of the light transmitting plate 2A. In the recess forming step ST2, the back surface 2R of the translucent plate 2A is sucked and held on a chuck table (not shown) of the cutting device 300, and a cutting blade 301 is used to cut the region RL that overlaps the division line L of the translucent plate 2A. The recess 4 is formed. In the disclosed example, the recess forming step ST2 moves the chuck table of the cutting device 300 and the cutting blade 301 along the machining feed direction X, the index feed direction Y, and the cutting feed direction Z, thereby performing cutting. It applies to the translucent plate 2A.

  As shown in FIGS. 26 and 27, the translucent plate 2 after the recess forming step ST2 of the manufacturing method according to the disclosed example is formed with the recesses 4 along the planned dividing line L, and at the time of cutting. Due to the crushing force of the cutting blade 301, chipping (chip) occurs at the edge of the inner surface 4a of the recess 4 near the surface 2S, and the irregularly shaped portion PL-2 is formed. The irregularly shaped portion PL-2 is a portion where irregularities finer than the flat surface near the bottom surface 4b of the inner surface 4a of the recess 4 are formed, and in the disclosed example, the range is 10 μm from the surface 2S of the inner surface 4a of the recess 4. It is formed in the AR.

  In the disclosed example, the range AR in which the irregularly shaped portion PL-2 is formed is in the range AR of 10 μm from the surface 2S, the thickness T of the light transmitting plate 2A is 0.7 mm to 10 mm, and the depth DP of the recess. Is about 20 μm. In the disclosed example, the shape of the cutting edge of the cutting blade 301 is gradually rounded, the dimension is reduced in the depth direction, and the dimension of the recess 4 is reduced when the surface is cut from the surface 2S. And compared with the case where the concave portion 4 is formed by the laser beam LR as in the second embodiment, the range AR where the irregularly shaped portion PL-2 is formed approaches the bottom surface 4b of the concave portion 4, so that the concave portion 4 is formed deeply. .

  In the manufacturing method according to the disclosed example, the light shielding material embedding step ST3 and the thinning step ST4 shown in FIG. 28 are sequentially performed after the recess forming step ST2 as in the first embodiment. In this way, the photomask 1 shown in FIG. 29 is obtained by the manufacturing method according to the disclosed example.

  Similar to the first embodiment, the manufacturing method according to the disclosed example can remove the irregularly shaped portion PL-2 without covering the protective film in the recess forming step ST2, and can perform patterning as designed. Can be manufactured more accurately at a low cost.

  The disclosed example shows a manufacturing method in which the recess forming step ST2 is different from the first embodiment and the other steps are the same as those in the first embodiment. However, the recess forming step ST2 is different from the second embodiment and other steps are performed. The manufacturing method which is the same as that of the second embodiment may be used.

  In addition, this invention is not limited to the said embodiment and modification. That is, various modifications can be made without departing from the scope of the present invention.

1, 1-2 Photomask for wafer processing 2, 2A Translucent plate 2S Front surface 2R Back surface 4 Recessed portion 5 Light shielding material W, W ′, W ″ Wafer LR Laser light RL Area that overlaps the planned division line (light should be shielded region)
TM Photomask thickness (predetermined thickness)
ST1 Preparation process ST2 Concave formation process ST3 Shading material embedding process ST4 Thinning process

Claims (1)

A method of manufacturing a photomask for wafer processing,
A preparation step of preparing a light-transmitting plate having a size larger than a wafer to be processed and transmitting light;
A recess forming step for forming a recess having a depth that does not reach the back surface of the light transmitting plate by irradiating the surface of the light transmitting plate with laser light in a region where light should be shielded;
A light shielding material embedding step of embedding a light shielding material for shielding light in the concave portion after the recess forming step;
A method of manufacturing a photomask for wafer processing, comprising a thinning step of holding a back surface side of the translucent plate and thinning the translucent plate to a predetermined thickness together with the light shielding material embedded from the front surface side.

Images