JP2009016538A - Wafer surface protective tape, and wafer grinding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer surface protective tape capable of being excellently peeled from a wafer surface without causing peeling defects or the chipping or cracking of a wafer or the like, since the sensor recognition property of the sensor recognition part of the wafer in a peeling process is excellent, positioning defects or the like are hardly caused and adhesion of a base material film back surface to a peeling tape is high. <P>SOLUTION: The wafer surface protective tape 10 is used in the process of sticking the surface side of a base material film to the surface of the wafer provided with the sensor recognition part and grinding the back surface of the wafer. The back surface of the base material film has a coarse region 20 where center line average roughness (Ra) is 1-9 μm and flat regions 22 and 24 where the center line average roughness (Ra) is ≤0.5 μm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wafer surface protection tape and a wafer grinding method using the same, and more specifically, a wafer surface protection tape used for protecting a wafer surface in a wafer grinding process in various semiconductor manufacturing processes, and the same. The present invention relates to a wafer grinding method.

  In the semiconductor wafer manufacturing process, after forming a pattern on the wafer surface, a so-called back grinding process is performed in which the back surface of the wafer is ground to a predetermined thickness. At that time, in general, for the purpose of protecting the wafer surface, a wafer surface protection tape is bonded to the wafer surface, and the wafer back surface is ground in that state. As disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-338911 (Patent Document 1), the wafer surface protective tape is provided with an adhesive layer on the surface side of the base film, and a separator is provided on the adhesive layer as necessary. It is used (see Patent Document 1 0013, FIG. 1), and in a state where the separator is peeled off, the surface side of the base film is adhered to the wafer surface with an adhesive layer.

  The wafer surface protection tape is generally unnecessary in the steps after the back grinding process, and after the back grinding process, for example, as disclosed in JP-A-5-62950 (Patent Document 2), the wafer surface protection tape is used. Affix the release tape to the back of the tape base film (the outermost surface exposed to the outside), and peel off the wafer surface protection tape from the wafer by turning the release tape sharply with respect to the wafer. (See Patent Document 2 0019, FIG. 5).

  The above-described wafer surface protective tape peeling step is generally performed in a state where the back surface of the wafer is vacuum-fixed and fixed by a vacuum suction-fixing device. In addition, the vacuum suction fixing of the back surface of the wafer, the application of the release tape, and the release of the release tape are performed by, for example, recognizing with a sensor a sensor recognition unit (see FIG. 3 described later) provided in a part on the outer periphery of the wafer The vacuum suction fixing position, the attaching position, the peeling position, etc. are determined.

JP 2002-338911 A JP-A-5-62950

  In the back grinding process, grinding dust (silicon dust or the like) generated by grinding the back surface of the wafer adheres to the back surface of the substrate film, which is the outermost surface of the wafer surface protective tape, and causes the following problems. That is, when the wafer is subjected to the wafer surface protection tape peeling step with the grinding dust adhered to the back surface of the base film, the sensor recognition is reduced because the grinding dust covers the sensor recognition unit, and the wafer is peeled off. Wafer positioning failure occurs in the process, and as a result, the wafer surface protection tape may not be peeled off or tape peeling failure may occur. In an extreme case, an excessive external force due to peeling is transmitted to the wafer fixed at the shifted position, and the wafer may be chipped or cracked.

  Furthermore, in the peeling step, the adhesive force between the back surface of the base film of the wafer surface protective tape and the peeling tape is important. If the adhesive force between them is insufficient, the wafer surface protective tape may be poorly peeled. Occur.

  The present invention has been made in view of the above-described circumstances, and is a wafer surface protective tape used for protecting the wafer surface, in which the sensor recognizability of the sensor recognition unit of the wafer in the peeling process is good, positioning failure, etc. Wafer surface protection tape that can be easily peeled off from the wafer surface without causing defective peeling, chipping or cracking of the wafer, and the like. An object is to provide a wafer grinding method using the same.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that the center line average roughness (Ra) on the back surface of the base film of the wafer surface protective tape is a wafer of grinding dust (silicon dust or the like). The present inventors have found that the adhesion of the surface protection tape to the back surface of the base film and the sensor recognizability are greatly affected, and further the adhesiveness with the release tape is greatly affected.

  In order to achieve the above object, the present invention provides a wafer surface protective tape used in a process of bonding the front surface side of a base film to the surface of a wafer having a sensor recognition unit and grinding the back surface of the wafer. The wafer surface, wherein the back surface of the material film has a roughened region having a centerline average roughness (Ra) of 1 to 9 μm and a flat region having a centerline average roughness (Ra) of 0.5 μm or less. Provide protective tape.

Further, the present invention is a wafer grinding method for grinding a back surface of a wafer by laminating a wafer surface protective tape on the surface of a wafer having a sensor recognition unit,
While using the wafer surface protection tape of the present invention as the wafer surface protection tape,
Bonding the surface side of the base film to the surface of the wafer so that at least a part of the flat region overlaps the sensor recognition unit of the wafer;
Grinding the backside of the wafer;
After grinding the back surface of the wafer, applying a release tape to at least a part of the roughened region of the back surface of the base film,
There is provided a wafer grinding method characterized by performing a step of peeling the wafer surface protection tape from the wafer by turning up the peeling tape on the wafer.

  In the flat region on the back surface of the base film in the wafer surface protection tape of the present invention, Ra is 0.5 μm or less, so that grinding dust (silicon dust or the like) generated by grinding in a back grinding process or the like is difficult to adhere to the surface. Therefore, the sensor recognizability of the wafer sensor recognition unit in the peeling process is good by bonding the surface side of the base film to the surface of the wafer so that at least a part of the flat region overlaps the sensor recognition unit of the wafer. Therefore, it is possible to make it difficult for a wafer positioning failure to occur, so that it is possible to prevent the occurrence of tape peeling failure, chipping or cracking of the wafer. Moreover, since Ra is 1-9 micrometers in the roughening area | region of the base film back surface in this invention wafer surface protection tape, the adhesive force of the surface and peeling tape becomes high. Therefore, the wafer surface protective tape can be peeled from the wafer without causing a peeling failure by applying a peeling tape to at least a part of the roughened area and turning the peeling tape over the wafer. .

  According to the wafer surface protective tape and the wafer grinding method according to the present invention, the sensor recognizing part of the wafer sensor recognition part in the peeling step is good, positioning failure and the like are unlikely to occur, and the back surface of the base film of the wafer surface protective tape Since the adhesive strength between the wafer surface and the peeling tape is high, the wafer surface protective tape can be favorably peeled from the wafer surface without causing defective peeling and chipping or cracking of the wafer.

  Hereinafter, the present invention will be described in more detail. FIG. 1 is a partial sectional view showing an embodiment of a wafer surface protection tape according to the present invention. As shown in FIG. 1, the wafer surface protective tape 10 of this example is provided with an adhesive layer 14 on a base film 12. Moreover, the separator 16 can be laminated | stacked on the adhesion layer 14 as needed. The wafer surface protection tape 10 can be formed in a flat plate shape or a tape shape wound in a roll shape. In addition, in the base film 12, the surface opposite to the surface in contact with the adhesive layer 14 is the back surface 18 of the base film 12, that is, the surface that becomes the outermost surface when attached to the wafer.

  Although the material of the base film 12 is not particularly limited, for example, low density polyethylene, linear polyethylene, medium density polyethylene, high density polyethylene, ultra-low density polyethylene, random copolymer polypropylene, block copolymer polypropylene , Polyolefins such as homopolyprolene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester (random, alternating) Polymer, ethylene-butene copolymer, ethylene-hexene copolymer, polyurethane, polyester such as polyethylene terephthalate, polyimide, polyether ether ketone, polyvinyl chloride, polyvinylidene chloride, fluororesin, cellulose resin, and Polymers such as those crosslinked products thereof. The polymer may be used alone, or several kinds may be blended as necessary, or may be used as a multilayer structure.

  The thickness of the base film 12 is usually about 10 to 300 μm, more preferably about 30 to 200 μm. The base film 12 can be formed by a conventionally known film forming method. For example, a wet casting method, an inflation extrusion method, a T-die extrusion method, or the like can be used. The base film 12 may be used without stretching or may be subjected to uniaxial or biaxial stretching treatment as necessary.

  In the wafer surface protection tape 10 according to the present invention, the back surface 18 of the base film 12 has a roughened region with Ra of 1 to 9 μm and a flat region with Ra of 0.5 μm or less. Ra of the roughened region is more preferably 1.5 to 8 μm, and Ra of the flat region is more preferably 0.3 μm or less.

  If Ra of the roughened region is less than 1 μm or exceeds 9 μm, the adhesive force between the peeling tape and the surface of the roughened region becomes insufficient, and a peeling failure of the wafer surface protection tape from the wafer may occur. is there. When the Ra of the flat region exceeds 0.5 μm, grinding dust (silicon dust, etc.) generated by grinding tends to adhere to the back surface of the base film of the wafer surface protection tape, covering the sensor recognition part of the semiconductor wafer. The sensor recognizability is lowered, and a positioning failure occurs in the peeling process. As a result, the wafer surface protection tape may not be peeled off or a peeling failure may occur.

  The position, shape, area ratio, etc. of each of the roughened region and the flat region are not particularly limited. For example, as shown in FIG. 2, the flat region 20 is provided in a strip shape, and the regions on both sides thereof are roughened regions 22, 24. And an embodiment. In the embodiment of FIG. 2, the base film is pressed or rolled with a roll having a flat portion that can form a belt-like flat region 20 and roughened portions that can form roughened regions 22 and 24 on both sides of the flat portion. Thus, it can be easily manufactured.

  In addition, the method for providing the roughened region and the flat region is not particularly limited. In addition to the method using the roll described above, for example, an embossing method, a sand plast method, an etching method, an electric discharge machining method, a satin treatment method, a mat treatment. It can be performed by various methods such as a method. The process which provides a roughening area | region and a flat area | region may be given at any time after film forming at the time of film forming of a base film.

  In addition, the higher the transmittance of the flat region on the back surface of the base film, the better the sensor recognizability, and in the peeling step, it is possible to further reduce positioning failure and peeling failure, which is preferable. The transmittance is the transmittance at the entire thickness of the wafer surface protective tape in the flat region on the back surface of the base film, and is a value obtained by measuring the total light transmittance in the wavelength region of the light source used for the sensor with a spectrophotometer. . Examples of the light source include red monochromatic light having a wavelength of about 610 nm, green monochromatic light of about 540 nm, blue monochromatic light of about 450 nm, or white light having these three wavelengths.

  Although the material of the adhesion layer 14 is not specifically limited, For example, a normal acrylic adhesive etc. are applicable. The acrylic pressure-sensitive adhesive contains a (meth) acrylic copolymer and a curing agent as components. Examples of the (meth) acrylic copolymer include a polymer having (meth) acrylic acid ester as a polymer constituent unit, a (meth) acrylic polymer of a (meth) acrylic acid ester copolymer, and (meth) ) A copolymer of an acrylate ester and a functional monomer, and a mixture of these polymers. As the molecular weight of these polymers, those having a weight average molecular weight of about 500,000 to 1,000,000 are generally applied.

  Moreover, the said hardening | curing agent is used in order to make it react with the functional group which a (meth) acrylic-type copolymer has, and to adjust adhesive force and cohesion force. Examples of the curing agent include 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, 1,3-bis (N, N-diglycidylaminomethyl) toluene, 1,3-bis (N, N -Diglycidylaminomethyl) benzene, N, N, N, N'-tetraglycidyl-m-xylenediamine and other epoxy compounds having two or more epoxy groups in the molecule, 2,4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylene diisocyanate, diphenylmethane-4,4′-diisocyanate and other isocyanate compounds having two or more isocyanate groups in the molecule, tetramethylol-tri -Β-aziridinylpropionate, trimethylol-tri-β-aziridinyl Aziridine compounds having two or more aziridinyl groups in the molecule such as lopionate, trimethylolpropane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β- (2-methylaziridine) propionate, etc. Can be mentioned. What is necessary is just to adjust the addition amount of a hardening | curing agent according to desired adhesive force, Preferably it is 0.1-5.0 mass parts with respect to 100 mass parts of (meth) acrylic-type copolymers.

  Although the thickness of the adhesion layer 14 can be selected suitably, generally it is about 1-300 micrometers or less, Preferably it is 3-200 micrometers, More preferably, it is 5-100 micrometers.

  The separator 16 is provided as necessary. Examples of the constituent material of the separator 16 include synthetic resin films such as paper, polyethylene, polypropylene, and polyethylene terephthalate. The surface of the separator 16 may be subjected to release treatment such as silicone treatment, long-chain alkyl treatment, fluorine treatment, etc., as necessary, in order to improve the peelability from the adhesive layer 14. The thickness of the separator 16 is usually about 10 to 200 μm, preferably about 25 to 100 μm.

  In the wafer grinding method according to the present invention, as described above, the surface side of the base film is attached to the surface of the wafer so that at least a part of the flat area of the wafer surface protection tape described above overlaps the sensor recognition unit of the wafer. A step of grinding, a step of grinding the back surface of the wafer, a step of pasting the release tape on at least a part of the roughened region of the back surface of the base film after grinding the back surface of the wafer, The process of peeling off the wafer surface protective tape from the wafer is performed by turning up.

  In this case, for example, the wafer shown in FIG. 3 can be used as the wafer. The wafer 26 in FIG. 3 is formed by forming a V-shaped cut (V notch) 28 as a sensor recognition part in a part of the outer periphery. However, the shape and structure of the sensor recognition unit can be set as appropriate.

  In the process of attaching the wafer surface protection tape to the wafer, the wafer scraping tape (silicon dust, etc.) generated by grinding is bonded to the sensor recognition unit of the wafer so that at least a part of the flat area of the wafer surface protection tape overlaps. It becomes difficult to adhere to the part corresponding to the sensor recognition part on the back surface of the base film. Therefore, the sensor recognizability of the wafer sensor recognition part is good in the peeling process, it is difficult to cause positioning failure, etc., so that the wafer surface protection tape can be peeled off from the wafer surface without causing wafer chipping or cracking. Become.

  Also, in the process of applying the release tape to the wafer surface protection tape, the adhesive force between the wafer surface protection tape and the release tape is increased by applying the release tape to at least a part of the roughened area of the wafer surface protection tape. Thus, the wafer surface protective tape can be satisfactorily peeled from the wafer surface.

  Bonding the wafer sensor recognition unit so that at least part of the flat area of the wafer surface protection tape overlaps, grinding the back surface of the wafer, peeling tape on at least part of the roughened area of the wafer surface protection tape There is no particular limitation on the method of performing the process of peeling the wafer surface protection tape from the wafer by turning up the release tape on the wafer, but for example, in the process of bonding the wafer surface protection tape to the wafer As shown in FIG. 4, the wafer surface protective tape 10 in which the flat region 20 is provided in a band shape and the other regions are roughened regions 22 and 24 is applied to the sensor recognition unit 28 of the wafer 26. What is necessary is just to bond together so that a part of 20 may overlap.

  Further, for example, in the step of attaching the release tape to the wafer surface protection tape, as shown in FIG. 5, the wafer surface protection tape is provided with a flat region 20 in a strip shape and the other regions are roughened regions 22 and 24. In a state where 10 is bonded to the wafer 26, the release tape 30 may be applied so as to cover a part of the roughened regions 22 and 24 of the wafer surface protection tape 10. At that time, the larger the area of the roughening regions 22, 24 of the release tape 30, the higher the adhesive force between the release tape 30 and the wafer surface protection tape 10, which is preferable.

  Further, the release tape used in the wafer grinding method according to the present invention is not particularly limited, but the adhesion between the back surface of the base film of the wafer surface protection tape and the release tape with respect to the adhesive force between the wafer and the wafer surface protection tape. It is preferable that the force is relatively high.

  EXAMPLES Next, although this invention is demonstrated further in detail based on an Example and a comparative example, this invention is not limited to the following Example. First, production of a wafer surface protective tape, bonding of a wafer surface protective tape, wafer back grinding, sensor recognition test, and peelability test using a release tape were performed as follows to confirm the effect of the present invention.

(Production of wafer surface protection tape)
For one surface of an ethylene-methyl methacrylate copolymer (EMMA) film (“ACRIFT WD-210” (trade name, manufactured by Sumitomo Chemical Co., Ltd.)), Ra has the value shown in Table 1. Then, it was pressed with a roll. On the non-processed surface of the base film, an acrylic pressure-sensitive adhesive (acrylic acid ester copolymer is 100 parts by mass, curing agent ("Coronate L" (trade name, manufactured by Nippon Polyurethane Co., Ltd.) is 2 parts by mass). Coating and drying were carried out to produce wafer surface protective tapes 1 to 10 having a 30 μm-thick adhesive layer on a base film, where Ra is a Tokyo Seimitsu Handy Surf E− per 10 points according to JIS B0601. It is the value measured and averaged using 30A.

(Lamination of wafer surface protection tape, wafer back surface grinding)
The wafer surface protective tape obtained by the above method is bonded to the surface of a 650 μm thick 8-inch silicon wafer having a sensor recognition part (V notch) as shown in FIG. Wafer backside grinding was performed with a grinder “DFG8560” (trade name) to a surface roughness of “# 2000” and a final finished thickness of 200 μm.

(Sensor recognition test)
Whether or not the sensor recognition part of the wafer was recognized by the sensor was evaluated in a state where the back surface of the wafer after grinding was vacuum suction fixed by a vacuum suction fixing device. A three-wavelength fluorescent lamp was used as the sensor light source. The results are shown in Table 1. In the table, ◎ indicates that the recognizability by the sensor is very excellent, ○ indicates that the recognizability by the sensor is at a level that does not cause a problem in practice, and × indicates that there is a problem in the recognizability by the sensor.

(Peelability with peeling tape)
Then, at the relative position of the release tape to the sensor recognition part of the wafer as shown in FIG. 5, the release tape is attached to the back surface of the base film of the wafer surface protection tape, and the release tape is turned up with respect to the wafer. The peelability of the wafer surface protective tape from the wafer was evaluated. As the release tape, a tape having a relatively higher adhesive force between the back surface of the base film of the wafer surface protection tape and the release tape than the adhesive force between the wafer and the wafer surface protection tape was used. The results are shown in Table 1. ◎ in the table indicates that the wafer surface protective tape can be peeled off from the wafer without any problem, ○ indicates that the wafer surface protective tape can be peeled off from the wafer, although x is partially peeled between the wafer surface protective tape and the peeling tape, and x indicates that the wafer is peeled off from the wafer. Indicates that the surface protection tape cannot be peeled off.

  According to Table 1, with respect to sensor recognizability, the sensor recognizability is good if Ra on the back surface of the base film of the surface protection tape is 0.5 μm or less, and the sensor recognizability is more excellent if it is 0.3 μm or less. I understand that. Moreover, regarding the peelability, it can be seen that if the Ra on the back surface of the base film of the surface protective tape is 1 to 9 μm, the peelability is good, and if it is 1.5 to 8 μm or less, the peelability is more excellent.

Example 1
Affixed to an 8-inch wafer as shown in FIG. 3 on one side of an ethylene-methyl methacrylate copolymer (EMMA) film (“ACRIFT WD-210” (trade name, manufactured by Sumitomo Chemical Co., Ltd.)). A band-shaped flat area of Ra 0.2 μm that overlaps the sensor recognition part of the wafer when combined, and a roughened area of Ra 2 μm on both sides thereof were pressed with a roll. On the non-processed surface of the base film, an acrylic pressure-sensitive adhesive (acrylic ester copolymer is 100 parts by mass, curing agent ("Coronate L" (trade name, manufactured by Nippon Polyurethane Co., Ltd.) is 2 parts by mass). The wafer surface protection tape which apply | coated and dried and provided the 30 micrometer adhesion layer on the base film was produced.

  The obtained wafer surface protective tape is applied to the surface of a 650 μm thick 8-inch silicon wafer having a sensor recognition portion (V notch) as shown in FIG. Bonding was performed so that part of the flat region overlapped. Thereafter, the wafer back surface was ground with a surface roughness “# 2000” and a final finished thickness of 200 μm using a disco grinder “DFG8560” (trade name).

  Whether or not the sensor recognition part of the wafer is recognized by the sensor in a state where the back surface of the wafer after grinding is vacuum suction fixed by a vacuum suction fixing device was evaluated, the recognizability was very excellent.

  Then, at the relative position of the release tape to the sensor recognition part of the wafer as shown in FIG. 5, the release tape is attached to the back surface of the base film of the wafer surface protection tape, and the release tape is turned up against the wafer. When the peelability of the wafer surface protection tape was evaluated, the wafer surface protection tape could be peeled from the wafer without any problem. As the release tape, a tape having a relatively higher adhesive force between the back surface of the base film of the wafer surface protection tape and the release tape than the adhesive force between the wafer and the wafer surface protection tape was used.

(Comparative Example 1)
Ra is 0.2 μm with respect to the entire surface of one side of an ethylene-methyl methacrylate copolymer (EMMA) film (“ACRIFT WD-210” (trade name, manufactured by Sumitomo Chemical Co., Ltd.)). A wafer surface protective tape was produced in the same manner as in Example 1 except that the pressing process was performed using a roll.

  The obtained wafer surface protective tape was bonded to the surface of a 650 μm-thick 8-inch silicon wafer having a sensor recognition portion (V notch) as shown in FIG. 3, and then a disco grinder “DFG8560” ( Under the trade name, the wafer back surface was ground so that the surface finish was “# 2000” and the final finished thickness was 200 μm.

  Whether or not the sensor recognition part of the wafer is recognized by the sensor in a state where the back surface of the wafer after grinding is vacuum suction fixed by a vacuum suction fixing device was evaluated, the recognizability was very excellent.

  Then, using the same release tape as in Example 1, the release tape was attached to the back surface of the base film of the wafer surface protective tape at the relative position of the release tape to the sensor recognition portion of the wafer as shown in FIG. When the peelability of the wafer surface protection tape from the wafer was evaluated by turning the tape over the wafer, the wafer surface protection tape could not be peeled from the wafer.

(Comparative Example 2)
Roll with an ethylene-methyl methacrylate copolymer (EMMA) film (“ACRIFT WD-210” (trade name, manufactured by Sumitomo Chemical Co., Ltd.)) with a roll so that Ra is 2 μm with respect to the entire surface of one side. A wafer surface protective tape was prepared in the same manner as in Example 1 except that the pressing process was performed.

  The obtained wafer surface protective tape was bonded to the surface of a 650 μm thick 8-inch silicon wafer having a sensor recognition part (V notch) as shown in FIG. 3, and then a disco grinder “DFG8560” (trade name) The wafer backside grinding was performed so that the final finish thickness was 200 μm with a surface roughness of “# 2000”.

  Whether or not the sensor recognition unit of the wafer was recognized by the sensor in a state where the back surface of the wafer after grinding was vacuum suction fixed by a vacuum suction fixing device was evaluated, there was a problem in recognition by the sensor.

  Then, using the same release tape as in the example, the release tape was attached to the back surface of the base film of the wafer surface protection tape at the relative position of the release tape to the sensor recognition portion of the wafer as shown in FIG. When the peelability of the wafer surface protection tape from the wafer was evaluated by turning up the wafer with respect to the wafer, the wafer surface protection tape could be peeled from the wafer without any problem.

It is a partial sectional view showing one embodiment of a wafer surface protection tape concerning the present invention. It is a top view of the wafer surface protection tape of FIG. It is a top view which shows an example of the wafer which comprises a sensor recognition part. It is a top view which shows the state which bonded the wafer surface protection tape of FIG. 1 on the surface of the wafer of FIG. It is a top view which shows the state which affixed the peeling tape on the wafer surface protection tape bonded together on the surface of the wafer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wafer surface protection tape 12 Base film 14 Adhesion layer 16 Separator 18 Back surface 20 of base film Flat area 22 Rough area 24 Rough area 26 Wafer 28 Sensor recognition part 30 Release tape

Claims (2)

  A wafer surface protective tape used in a process of bonding a front surface side of a base film to a front surface of a wafer having a sensor recognition unit and grinding the back surface of the wafer, wherein the back surface of the base film has a center line average roughness A wafer surface protective tape comprising a roughened region (Ra) of 1 to 9 μm and a flat region having a center line average roughness (Ra) of 0.5 μm or less. A wafer grinding method for grinding a back surface of a wafer by attaching a wafer surface protective tape to the surface of a wafer having a sensor recognition unit,
While using the wafer surface protection tape according to claim 1 as the wafer surface protection tape,
Bonding the surface side of the base film to the surface of the wafer so that at least a part of the flat region overlaps the sensor recognition unit of the wafer;
Grinding the backside of the wafer;
After grinding the back surface of the wafer, applying a release tape to at least a part of the roughened region of the back surface of the base film,
And a step of peeling the wafer surface protection tape from the wafer by turning up the peeling tape on the wafer.

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