JP2005303214A - Grinding method for semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding method that can decrease thickness variations of a semiconductor wafer. <P>SOLUTION: When the backside of a semiconductor wafer 2, on whose surface an integrated circuit layer 1 composed of multiple semiconductor elements is formed, is ground to make its thickness uniform, the steps are carried out of forming a protective film 11 from a liquid resinous material that protects the integrated circuit and metal bump composing the semiconductor elements by covering the surface of the semiconductor wafer 2, grinding and leveling off the surface of the protective film 11, grinding the backside of the semiconductor wafer 2 using a grinding stone while keeping the leveled-off surface of the protective film 11 in contact with the top of the chuck table 4. Through such an easy method as protects the semiconductor elements on the surface of the semiconductor wafer 2 not by sticking a conventional protective tape on it but by forming the protective film 11 with a liquid resinous material and gets the surface of the protective film 11 ground and leveled off prior to grinding the backside of the semiconductor wafer 2, uniformity of the semiconductor wafer 2's thickness can be significantly improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for grinding a semiconductor wafer in which the thickness of the semiconductor wafer is made uniform by grinding the back surface of a semiconductor wafer having a plurality of semiconductor elements formed on the surface, and in particular, a grinding method that improves the thickness accuracy of the semiconductor wafer. It is about.

  When packaging and mounting a semiconductor chip or COG (Chip on Glass) mounting, the semiconductor chip is required to have high thickness accuracy. For this purpose, backside grinding of semiconductor wafers on which integrated circuits such as IC and LSI are formed is performed.

  In general, as shown in FIG. 7, a protective tape 3 for circuit protection is rolled onto a semiconductor wafer 2 (FIG. 7 (a)) having an integrated circuit layer 1 on which a plurality of integrated circuits such as IC and LSI are formed. 3a is attached to the surface (FIG. 7 (b)), the protective tape 3 is cut out along the outer shape of the semiconductor wafer 2 (FIG. 7 (c)), and the semiconductor wafer 2 is then chucked on the back grinding apparatus. 4 is held by vacuum suction with the protective tape 3 facing down (FIG. 7 (d)), and a grinding wheel 5 that rotates is brought into contact with the back surface that faces upward, and is pressed to a predetermined thickness by applying a pressing force. (FIG. 7 (e)), the protective tape 3 is peeled off after the grinding (FIG. 7 (f) (g)).

  As shown in FIG. 8, for the semiconductor wafer 2 on which metal bumps 6 for electrically connecting the integrated circuits of the integrated circuit layer 1 to the outside are formed (FIG. 8A), the metal bumps 6 are buried. After applying the protective tape 3 having a thick adhesive layer 3b (FIG. 8 (b)), the same procedure is performed (FIG. 8 (c) (d) (e) (f) (g)) The stress generated in the metal bump 6 due to the pressing force at the time of grinding is relieved, and deformation of the metal bump 6 and cracking of the semiconductor wafer 2 due to the concentration of stress are prevented.

However, the back grinding method using the protective tape 3 has various problems.
The first problem is the thickness variation of the protective tape 3. The protective tape 3 for backside grinding is manufactured by applying an acrylic adhesive to the surface of a film having a certain thickness, and uneven application of the adhesive may occur. The thickness of 3 varies by about 3 to 10 μm. Due to the influence of the thickness variation of the protective tape 3, the thickness variation of the semiconductor wafer 2 to which the protective tape 3 is attached and the back surface grinding is performed regardless of the thickness processing accuracy of the back grinding apparatus being about 1 to 2 μm Becomes larger and has a variation of about 4 to 12 μm.

  The second problem is that air bubbles may be sandwiched between the surface of the semiconductor wafer 2 when the protective tape 3 is stuck, and the thickness of the semiconductor wafer 2 is locally reduced at the air bubbles when grinding the back surface. The wafer 2 may be cracked or cracked.

  The third problem is that the protection by the protective tape 3 cannot sufficiently remove the stress of the metal bump 6, and the deformation of the metal bump 6 and the cracking of the semiconductor wafer 2 cannot be completely prevented.

For this reason, a method of forming a resist film or the like and grinding the back surface instead of attaching the protective tape 3 to the semiconductor wafer 2 has been proposed. For example, as shown in FIG. 9, a resist film 7 is formed so as to cover the integrated circuit layer 1 on the semiconductor wafer 2 (FIG. 9A) on which the integrated circuit layer 1 is formed (FIG. 9B). )), The resist film 7 in the region where the metal bumps are to be formed corresponding to each integrated circuit of the integrated circuit layer 1 is exposed using the light source 8 and the photomask 9 (FIG. 9C) and developed. After forming a plurality of pores 10 (FIG. 9 (d)) and plating each pore 10 to form metal bumps 6 (FIG. 9 (e)), the semiconductor wafer 2 is coated with the resist film 7. The semiconductor wafer 2 provided with the metal bumps 6 is obtained by holding the chuck table 4 so as to face and grinding the back surface to a predetermined thickness (FIG. 9 (f)), removing the resist film 7 (FIG. 9 (g)). A method of obtaining (FIG. 9 (h)) is disclosed (for example, Patent Document 1).
JP 2003-51473 A (page 4, FIG. 8)

  In the back surface grinding method using the resist film 7 described above, the thickness variation due to bubble mixing when the protective tape 3 is stuck, which has been a problem with the conventional methods, cracks in the semiconductor wafer 2 due to bubbles or stress, and metal bumps 6 The deformation of can be avoided.

  However, on the other hand, the protective film such as the resist film 7 is formed by spreading a liquid resin material such as a resist dropped on the surface of the semiconductor wafer 2 by rotating the semiconductor wafer 2 and then curing it with a hot plate or the like. The film thickness variation from the central part of the semiconductor wafer 2 toward the outer peripheral direction may occur, or the resin material may rise at the outer peripheral edge of the semiconductor wafer 2. Therefore, also in this case, the back surface grinding is performed using a film having a large thickness variation as a protective film, and the thickness variation of the semiconductor wafer 2 after the back surface grinding cannot be sufficiently improved.

  The present invention solves the above problems, and an object thereof is to provide a semiconductor wafer grinding method capable of reducing thickness variation.

  In order to solve the above problems, the present invention does not protect the semiconductor elements on the surface of the semiconductor wafer with a protective tape, but protects the surface of the semiconductor wafer by forming a protective film with a liquid resin material. Prior to the back surface grinding, the surface is ground and flattened, whereby the thickness uniformity of the semiconductor wafer after the back surface grinding can be easily remarkably improved.

  According to a first aspect of the present invention, there is provided a method for grinding a semiconductor wafer, wherein when the back surface of the semiconductor wafer having a plurality of semiconductor elements formed on the surface is ground to make the thickness of the semiconductor wafer uniform, the surface of the semiconductor wafer is covered. Forming a protective film for protecting an integrated circuit and metal bumps constituting the semiconductor element with a liquid resin material, grinding and planarizing a surface of the protective film, and the planarized protection And a step of grinding the back surface of the semiconductor wafer by holding the surface of the film in contact with a stage and removing the protective film after the grinding.

  A semiconductor wafer grinding method according to a second aspect of the present invention is a semiconductor wafer grinding method for grinding the back surface of a semiconductor wafer having a plurality of semiconductor elements formed on the surface thereof to make the thickness of the semiconductor wafer uniform. A step of forming a protective film covering the surface of the wafer and protecting the integrated circuit constituting the semiconductor element with a photoresist material; and holding the back surface of the semiconductor wafer on the stage so that the surface of the protective film is A step of grinding and flattening, and an opening for exposing the external terminals of the plurality of semiconductor elements are formed in the flattened protective film by photolithography, and metal bumps connected to the external terminals are formed in the openings. The step of forming by plating and the surface of the protective film having the metal bumps in the opening are held in contact on the stage to Grinding the surface, and performing the step of removing the protective film after the grinding completion.

  According to a third aspect of the present invention, there is provided a semiconductor wafer grinding method for grinding a back surface of a semiconductor wafer having a plurality of semiconductor elements formed on the surface thereof to make the thickness of the semiconductor wafer uniform. Forming a protective film covering the surface of the wafer and protecting the integrated circuit constituting the semiconductor element with a photoresist material; and exposing openings for exposing the external terminals of the plurality of semiconductor elements to the protective film. A step of forming a metal bump connected to the external terminal in each opening by a plating method, and a surface of the protective film by holding the back surface of the semiconductor wafer having the metal bump on the stage in contact with each other Grinding the surface of the semiconductor wafer and grinding the back surface of the semiconductor wafer by holding the surface of the flattened protective film in contact with the stage. , And performs the step of removing the protective film after the grinding completion.

  In the semiconductor wafer grinding method described above, the protective film is formed thicker than the step formed on the surface of the semiconductor wafer by the integrated circuit of the semiconductor element or the metal bump, and is ground so as to remain thicker than the height of the metal bump. can do.

  In the semiconductor wafer grinding method described above, the protective film is formed thicker than the step formed on the surface of the semiconductor wafer by the integrated circuit of the semiconductor element or the metal bump, and when the protective film is ground, The top can also be ground.

  According to the method for grinding a semiconductor wafer of the present invention, an easy method of forming a protective film with a liquid resin instead of the conventional protective tape, and grinding and planarizing the protective film prior to the back surface grinding of the semiconductor wafer. Thus, variation in the thickness of the semiconductor wafer can be avoided.

  Further, by selecting a highly rigid resin as the protective film material, it is possible to sufficiently reduce the stress applied to the metal bumps during back surface grinding, and to prevent deformation of the metal bumps and cracking of the semiconductor wafer due to the stress.

  Disadvantages caused by conventional protective tape, that is, semiconductor wafer thickness variation due to protective tape thickness variation, local thinning or cracking of semiconductor wafer due to air bubbles being sandwiched between the protective tape and the semiconductor wafer surface, This is a method that can eliminate cracks.

Hereinafter, a semiconductor wafer grinding method of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a process cross-sectional view illustrating a semiconductor wafer grinding method according to a first embodiment of the present invention.

FIG. 1A shows a semiconductor wafer 2 to be ground, and has an integrated circuit layer 1 on which a plurality of integrated circuits such as IC and LSI are formed on the surface.
As shown in FIG. 1B, a protective film 11 is formed on the integrated circuit layer 1 of the semiconductor wafer 2 by a coating method or the like using a liquid resin material such as resist or polyimide. The protective film 11 is formed to be thicker than the unevenness of the integrated circuit layer 1. As a coating method, a spin coating method, a roll coating method, a slit coating method, or the like can be used.

  Next, as shown in FIG. 1 (c), the semiconductor film 2 is placed on the chuck table 4 of the grinding apparatus with the back side down, and the protective film 11 facing upward is held by vacuum suction. The grinding wheel 5 is rotated for grinding. At this time, the grinding amount is set so that the film thickness (t1) of the protective film 11 after grinding is smaller than the minimum film thickness (t2) of the protective film 11 before grinding.

  Next, as shown in FIG. 1 (d), as shown in FIG. 1 (e), the semiconductor wafer 2 is placed on the chuck table 4 with its protective film 11 down and held by vacuum suction. Then, the back surface of the semiconductor wafer 2 facing upward is ground with a grinding wheel 5. At this time, the grinding amount is set so that the thickness of the semiconductor wafer 2 after grinding becomes a desired thickness. After this grinding, polishing or etching may be performed as necessary to improve the chip breaking strength.

  Next, as shown in FIG. 1 (f), the semiconductor wafer 2 is removed from the chuck table 4, and the protective film 11 is removed by dissolving with a stripping solution such as an organic solvent or a developing solution. The semiconductor wafer 2 having a desired thickness (t3) having the integrated circuit layer 1 on the surface as shown in FIG.

  According to the grinding method as described above, the finishing thickness accuracy after grinding of the semiconductor wafer 2 including the protective film 11 is obtained by grinding the back surface of the semiconductor wafer 2 after grinding the surface of the protective film 11. The thickness processing accuracy of the grinding device (chuck table 4, grinding wheel 5) is about 1 to 2 μm, and is about 1 to 4 μm. Since the thickness processing accuracy in the conventional grinding method using the protective tape is 4 to 12 μm as described above, the accuracy is greatly improved.

The thickness of the protective film 11 may be 5 μm to several hundred μm before grinding and 1 μm to several hundred μm after grinding.
(Second Embodiment)
FIG. 2 is a process cross-sectional view illustrating a semiconductor wafer grinding method according to the second embodiment of the present invention.

  FIG. 2 (a) shows a semiconductor wafer 2 to be ground. An integrated circuit layer 1 on which a plurality of integrated circuits such as IC and LSI are formed, and each integrated circuit of the integrated circuit layer 1 is electrically connected to the outside. A plurality of metal bumps 6 are provided on the surface. The metal bump 6 may be formed of gold, solder, copper or the like by an electroless plating method, an electrolytic plating method, a printing method, or the like.

  As shown in FIG. 2B, a protective film 11 is formed on the integrated circuit layer 1 of the semiconductor wafer 2 by a coating method or the like using a liquid resin material such as resist or polyimide. The protective film 11 is formed to be thicker than the height of the metal bump 6.

  Next, as shown in FIG. 2 (c), the semiconductor wafer 2 is placed on the chuck table 4 of the grinding apparatus with the back side down, and the protective film 11 facing upward is held in a vacuum suction state. The grinding wheel 5 is rotated for grinding. At this time, the film thickness (t1) of the protective film 11 after grinding is smaller than the minimum film thickness (t2) of the protective film 11 before grinding and larger than the maximum height (t4) of the metal bump 6. Set the grinding amount.

  Next, as shown in FIG. 2D, the semiconductor wafer 2 is placed on the chuck table 4 with the protective film 11 facing down and held by vacuum suction as shown in FIG. Then, the back surface of the semiconductor wafer 2 facing upward is ground with a grinding wheel 5. At this time, the grinding amount is set so that the thickness of the semiconductor wafer 2 after grinding becomes a desired thickness. After this grinding, polishing or etching may be performed as necessary.

  Next, as shown in FIG. 2 (f), the semiconductor wafer 2 is removed from the chuck table 4, and the protective film 11 is dissolved and removed with a stripping solution or a developing solution, as shown in FIG. 2 (g). A semiconductor wafer 2 having a desired thickness (t3) having the metal bumps 6 and the integrated circuit layer 1 on the surface is obtained.

  As described above, as in the first embodiment, the finishing thickness accuracy after grinding of the semiconductor wafer 2 including the protective film 11 is greatly improved as compared with the grinding method using the conventional protective tape.

  Furthermore, the conventional grinding method using a protective tape or a resist film cannot sufficiently remove the stress on the metal bump 6 during back grinding, and completely prevents deformation of the metal bump 6 and cracking of the semiconductor wafer 2. On the other hand, in the grinding method of the second embodiment, by selecting a resin material having high rigidity for the protective film 11, the stress on the metal bump 6 can be sufficiently removed, and the metal bump can be removed. 6 deformation and cracking of the semiconductor wafer 2 can be prevented.

The protective film 11 may have a thickness before grinding of several tens of μm to several hundreds of μm, and a thickness after grinding of several μm to several hundreds of μm. Further, the metal bump 6 may be formed and ground so as to satisfy the above-mentioned conditions in the range of several μm to several hundred μm in diameter and several μm to several hundred μm in height. The same applies to the following embodiments.
(Third embodiment)
FIG. 3 is a process cross-sectional view illustrating a semiconductor wafer grinding method according to a third embodiment of the present invention.

  Similar to the second embodiment described above, a semiconductor having an integrated circuit layer 1 having a plurality of integrated circuits such as IC and LSI and a plurality of metal bumps 6 on its surface as shown in FIG. As shown in FIG. 3B, the protective film 11 is applied on the integrated circuit layer 1 by a coating method using a liquid resin material such as a resist or polyimide on the integrated circuit layer 1 as shown in FIG. Form. The protective film 11 is thicker than the metal bump 6.

  Next, as shown in FIG. 3 (c), the semiconductor wafer 2 is placed on the chuck table 4 of the grinding apparatus with the back side down, and the protective film 11 facing upward is held by vacuum suction. The surface is ground with the grinding wheel 5. At this time, the grinding amount is set so that the film thickness (t 1) of the protective film 11 after grinding becomes thinner than the minimum height (t 5) of the metal bump 6. Then, the top of the metal bump 6 is also ground at the same time, and the height of the metal bump 6 is leveled.

  Thereafter, as in the second embodiment, as shown in FIG. 3 (d), the semiconductor wafer 2 is placed on the chuck table 4 with the protective film 11 facing down and held by vacuum suction. As shown in FIG. 3 (e), the back surface of the semiconductor wafer 2 facing upward is ground with a grinding wheel 5. At this time, the grinding amount is set so that the thickness of the semiconductor wafer 2 after grinding becomes a desired thickness. After this grinding, polishing or etching may be performed as necessary.

  Then, as shown in FIG. 3 (f), the semiconductor wafer 2 is removed from the chuck table 4 and the protective film 11 is dissolved and removed with a stripping solution or a developing solution, as shown in FIG. 3 (g). Then, a semiconductor wafer 2 having a desired thickness (t3) having the metal bumps 6 and the integrated circuit layer 1 on the surface is obtained.

Even in the grinding method of the third embodiment, the finished thickness accuracy of the semiconductor wafer 2 including the protective film 11 after grinding is greatly improved as compared with the grinding method using the conventional protective tape. Moreover, compared with the grinding method using the conventional protective tape and resist film, the stress to the metal bump 6 can be removed sufficiently, and the deformation of the metal bump 6 and the crack of the semiconductor wafer 2 can be easily prevented.
(Fourth embodiment)
FIG. 4 is a process cross-sectional view illustrating a semiconductor wafer grinding method according to the fourth embodiment of the present invention.

FIG. 4A shows a semiconductor wafer 2 to be ground, and has an integrated circuit layer 1 on the surface on which a plurality of integrated circuits such as IC and LSI are formed.
On the integrated circuit layer 1 of the semiconductor wafer, as shown in FIG. 4B, a protective film 11 made of a photoresist material is formed using a coating method or the like. The protective film 11 is formed to be thicker than the unevenness of the integrated circuit layer 1.

  Next, as shown in FIG. 4 (c), the semiconductor wafer 2 is placed on the chuck table 4 of the grinding apparatus with the back side down, and the protective film 11 facing upward is held by vacuum suction. The grinding wheel 5 is rotated for grinding. At this time, the grinding amount is set so that the film thickness (t1) of the protective film 11 after grinding is smaller than the minimum film thickness (t2) of the protective film 11 before grinding.

  Next, as shown in FIG. 4D, alignment of the pattern of the photomask 9 and each integrated circuit of the integrated circuit layer 1 of the semiconductor wafer 2 was performed in an exposure apparatus such as a projection aligner or a stepper exposure machine. Thereafter, the light source 8 selectively exposes a portion of the protective film 11 where metal bumps are to be formed on each integrated circuit (a portion where metal bumps should not be formed depending on the photoresist material).

Next, as shown in FIG. 4E, the protective film 11 is developed to form pores 10 in selectively exposed portions (or unexposed portions).
Next, as shown in FIG. 4 (f), the inside of the pores 10 is plated by an electroless plating method, an electrolytic plating method or the like to form metal bumps 6 such as gold, solder, and copper. At this time, the height of the metal bump 6 is set to be lower than the film thickness (t1) of the protective film 11 after grinding.

  Next, as shown in FIG. 4 (g), the semiconductor wafer 2 is placed on the chuck table 4 with the protective film 11 down and held by vacuum suction, and then the back surface of the semiconductor wafer 2 facing upward is placed. Grind with a grinding wheel 5. At this time, the grinding amount is set so that the thickness of the semiconductor wafer 2 after grinding becomes a desired thickness. After this grinding, polishing or etching may be performed as necessary.

  Next, as shown in FIG. 4 (h), the semiconductor wafer 2 is removed from the chuck table 4, and the protective film 11 is dissolved and removed with a stripping solution or a developing solution, as shown in FIG. 4 (i). A semiconductor wafer 2 having a desired thickness (t3) having the metal bumps 6 and the integrated circuit layer 1 on the surface is obtained.

Also in the grinding method of the fourth embodiment, the finished thickness accuracy of the semiconductor wafer 2 including the protective film 11 after grinding is greatly improved as compared with the grinding method using the conventional protective tape. Moreover, compared with the grinding method using the conventional protective tape and resist film, the stress to the metal bump 6 can be removed sufficiently, and the deformation of the metal bump 6 and the crack of the semiconductor wafer 2 can be easily prevented.
(Fifth embodiment)
FIG. 5 is a process cross-sectional view illustrating a semiconductor wafer grinding method according to a fifth embodiment of the present invention.

FIG. 5A shows a semiconductor wafer 2 to be ground, and has an integrated circuit layer 1 on the surface on which a plurality of integrated circuits such as IC and LSI are formed.
On the integrated circuit layer 1 of this semiconductor wafer, as shown in FIG. 5B, a protective film 11 made of a photoresist material is formed using a coating method or the like. The protective film 11 is formed to be thicker than the unevenness of the integrated circuit layer 1.

  Next, as shown in FIG. 5C, the alignment of the pattern of the photomask 9 and each integrated circuit of the integrated circuit layer 1 of the semiconductor wafer 2 was performed in an exposure apparatus such as a projection aligner or a stepper exposure machine. Thereafter, the light source 8 selectively exposes a portion of the protective film 11 where metal bumps are to be formed on each integrated circuit (a portion where metal bumps should not be formed depending on the photoresist material).

Next, as shown in FIG. 5D, the protective film 11 is developed to form pores 10 in selectively exposed portions (or unexposed portions).
Next, as shown in FIG. 5 (e), the inside of the pores 10 is plated by an electroless plating method, an electrolytic plating method or the like to form metal bumps 6 such as gold, solder, and copper. At this time, the height of the metal bump 6 is set to be sufficiently lower than the film thickness of the protective film 11.

  Next, as shown in FIG. 5 (f), the semiconductor wafer 2 is placed on the chuck table 4 with its back side down and held by vacuum suction, and then the protective film 11 facing upward is removed with a grinding wheel 5. Grind. At this time, the film thickness (t1) of the protective film 11 after grinding is smaller than the minimum film thickness (t2) of the protective film 11 before grinding and larger than the maximum height (t4) of the metal bump 6. Set the grinding amount to.

  Next, as shown in FIG. 5 (g), the semiconductor wafer 2 is placed on the chuck table 4 with its protective film 11 facing down and held by vacuum suction, and then as shown in FIG. 5 (h). The back surface of the semiconductor wafer 2 facing upward is ground with a grinding wheel 5. At this time, the grinding amount is set so that the thickness of the semiconductor wafer 2 after grinding becomes a desired thickness. After this grinding, polishing or etching may be performed as necessary.

  Next, as shown in FIG. 5 (i), the semiconductor wafer 2 is removed from the chuck table 4, and the protective film 11 is dissolved and removed with a stripping solution or a developing solution, as shown in FIG. 5 (j). A semiconductor wafer 2 having a desired thickness (t3) having the metal bumps 6 and the integrated circuit layer 1 on the surface is obtained.

Also in the grinding method of the fifth embodiment, the finished thickness accuracy after grinding of the semiconductor wafer 2 including the protective film 11 is greatly improved as compared with the grinding method using the conventional protective tape. Moreover, compared with the grinding method using the conventional protective tape and resist film, the stress to the metal bump 6 can be removed sufficiently, and the deformation of the metal bump 6 and the crack of the semiconductor wafer 2 can be easily prevented.
(Sixth embodiment)
FIG. 6 is a process cross-sectional view illustrating a semiconductor wafer grinding method according to a sixth embodiment of the present invention.

  Similar to the fifth embodiment described above, a semiconductor wafer 2 having an integrated circuit layer 1 having a plurality of integrated circuits such as IC and LSI formed thereon as shown in FIG. As shown in FIG. 6B, a protective film 11 made of a photoresist material is formed on the integrated circuit layer 1 using a coating method or the like. The protective film 11 is formed to be thicker than the unevenness of the integrated circuit layer 1.

  Then, after aligning the pattern of the photomask 9 and each integrated circuit of the integrated circuit layer 1 of the semiconductor wafer 2 in an exposure apparatus such as a projection aligner or a stepper exposure machine, as shown in FIG. The light source 8 selectively exposes a portion of the protective film 11 where a metal bump is to be formed on each integrated circuit (a portion where a metal bump should not be formed depending on the photoresist material).

  Then, as shown in FIG. 6 (d), the resin film 7 is developed to form pores 10 in selectively exposed portions (or unexposed portions), as shown in FIG. 6 (e). As described above, the inside of the pores 10 is plated by an electroless plating method, an electrolytic plating method, or the like to form metal bumps 6 such as gold, solder, and copper.

  Next, as shown in FIG. 6 (f), the semiconductor wafer 2 is placed on the chuck table 4 with its back side down and held by vacuum suction, and then the protective film 11 facing upward is removed with a grinding wheel 5. Grinding is performed, but here, unlike the fifth embodiment, the grinding amount is set so that the film thickness (t1) of the protective film 11 after grinding is thinner than the minimum height (t5) of the metal bump. Then, the top of the metal bump 6 is also ground at the same time, and the height of the metal bump 6 is leveled.

  Thereafter, as in the fifth embodiment, as shown in FIG. 6G, the semiconductor wafer 2 is placed on the chuck table 4 with the protective film 11 facing down and held by vacuum suction. As shown in 6 (h), the back surface of the semiconductor wafer 2 facing upward is ground with a grinding wheel 5. At this time, the grinding amount is set so that the thickness of the semiconductor wafer 2 after grinding becomes a desired thickness.

  Then, as shown in FIG. 6 (i), the semiconductor wafer 2 is removed from the chuck table 4, and the protective film 11 is dissolved and removed with a stripping solution, a developing solution or the like, as shown in FIG. 6 (j). Then, a semiconductor wafer 2 having a desired thickness (t3) having the metal bumps 6 and the integrated circuit layer 1 on the surface is obtained.

  Even in the grinding method of the sixth embodiment, the finishing thickness accuracy after grinding of the semiconductor wafer 2 including the protective film 11 is greatly improved as compared with the grinding method using the conventional protective tape. Moreover, compared with the grinding method using the conventional protective tape and resist film, the stress to the metal bump 6 can be removed sufficiently, and the deformation of the metal bump 6 and the crack of the semiconductor wafer 2 can be easily prevented.

  The semiconductor wafer grinding method of the present invention can be used in place of the conventional grinding method using a protective tape to improve the thickness accuracy, and manufacture of semiconductor chips for use in packages and packaging that require high thickness accuracy. Useful for.

  Even when gold bumps are formed on a semiconductor wafer, equivalent thickness processing accuracy can be achieved, and metal bump heights can be leveled at the same time, so COG (Chip on Glass) that requires particularly high chip thickness accuracy. It is also very effective in the manufacture of semiconductor chips used for mounting.

Process sectional drawing explaining the grinding method of the semiconductor wafer in the 1st Embodiment of this invention Process sectional drawing explaining the grinding method of the semiconductor wafer in the 2nd Embodiment of this invention Process sectional drawing explaining the grinding method of the semiconductor wafer in the 3rd Embodiment of this invention Process sectional drawing explaining the grinding method of the semiconductor wafer in the 4th Embodiment of this invention Process sectional drawing explaining the grinding method of the semiconductor wafer in the 5th Embodiment of this invention Process sectional drawing explaining the grinding method of the semiconductor wafer in the 6th Embodiment of this invention Process sectional drawing explaining the conventional grinding method of a semiconductor wafer Process sectional view explaining another conventional grinding method for semiconductor wafers Process sectional drawing explaining the conventional grinding method of another semiconductor wafer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Integrated circuit layer 2 Semiconductor wafer 4 Chuck table 5 Grinding wheel 6 Metal bump 8 Light source 9 Photomask 10 Fine pore (opening)
11 Protective film

Claims (5)

A method for grinding a semiconductor wafer in which the back surface of a semiconductor wafer having a plurality of semiconductor elements formed on the front surface is ground to make the thickness of the semiconductor wafer uniform,
Forming a protective film that covers the surface of the semiconductor wafer and protects the integrated circuit and metal bumps constituting the semiconductor element with a liquid resin material;
Grinding and planarizing the surface of the protective film;
A method of grinding a semiconductor wafer, comprising: holding a surface of the planarized protective film in contact with a stage to grind the back surface of the semiconductor wafer; and removing the protective film after the grinding is completed. A method for grinding a semiconductor wafer in which the back surface of a semiconductor wafer having a plurality of semiconductor elements formed on the front surface is ground to make the thickness of the semiconductor wafer uniform,
Forming a protective film that covers the surface of the semiconductor wafer and protecting the integrated circuit constituting the semiconductor element with a photoresist material;
A step of holding the back surface of the semiconductor wafer in contact with a stage and grinding and flattening the surface of the protective film;
Forming an opening exposing the external terminals of the plurality of semiconductor elements in the planarized protective film by a photolithography method, and forming a metal bump connected to the external terminal in each opening by a plating method;
A method for grinding a semiconductor wafer, comprising: holding a surface of a protective film having the metal bumps in an opening in contact with a stage, grinding a back surface of the semiconductor wafer, and removing the protective film after the grinding is completed. A method for grinding a semiconductor wafer in which the back surface of a semiconductor wafer having a plurality of semiconductor elements formed on the front surface is ground to make the thickness of the semiconductor wafer uniform,
Forming a protective film that covers the surface of the semiconductor wafer and protecting the integrated circuit constituting the semiconductor element with a photoresist material;
Forming an opening exposing the external terminals of the plurality of semiconductor elements in the protective film by a photolithography method, and forming a metal bump connected to the external terminal in each opening by a plating method;
The process of grinding and flattening the surface of the protective film by holding the back surface of the semiconductor wafer having the metal bumps in contact with the stage,
A method of grinding a semiconductor wafer, comprising: holding a surface of the planarized protective film in contact with a stage to grind the back surface of the semiconductor wafer; and removing the protective film after the grinding is completed.   The protective film is formed thicker than a step formed on the surface of the semiconductor wafer by an integrated circuit of a semiconductor element or a metal bump, and is ground so as to remain thicker than the height of the metal bump. The semiconductor wafer grinding method according to any one of the above.   4. The semiconductor wafer according to claim 3, wherein the protective film is formed thicker than the step formed on the surface of the semiconductor wafer by the integrated circuit of the semiconductor element or the metal bump, and the top of the metal bump is ground when the protective film is ground. Grinding method.

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