JP5168920B2 - Semiconductor device manufacturing method and marking device - Google Patents

Description

  The present invention relates to a method of manufacturing a semiconductor device and a marking device used when dicing a rib structure wafer having a metal electrode film formed on the back surface into chips.

  2. Description of the Related Art Conventionally, a semiconductor device having a metal electrode film on the back surface, such as a vertical IGBT and a vertical MOSFET, is known (see, for example, Patent Document 1 below). A general manufacturing process of such a semiconductor device will be described. First, a gate structure, a source / emitter structure, and the like are formed on the surface side of a thick wafer to form a surface side element structure portion (previous process). Next, polishing or etching is performed from the back side of the wafer to thin the wafer (wafer thinning step). Subsequently, a back diffusion layer and a back electrode are formed on the back surface of the thinned wafer (back surface forming step). Then, the wafer is diced to form individual chips (chip formation process).

  More specifically, for example, when a vertical IGBT is taken as an example, a wafer thinning process is performed after forming a surface-side element structure such as a gate structure and an emitter structure, and further, a back surface is formed by ion implantation and low-temperature furnace annealing or laser annealing. A collector diffusion layer is formed. Then, after a collector metal electrode film is formed by vapor deposition or sputtering, the wafer is diced as shown in FIG. 8 to form individual chips.

  FIG. 9 is an explanatory view schematically showing a dicing process for a wafer. As shown in FIG. 9, the back surface of the wafer 900 on which the metal electrode film 901 is formed is bonded to a dicing tape 910, and then the wafer 900 is cut from the front surface of the wafer 900 using a dicing blade 920 or the like. To do. At this time, several points in the wafer 900 are observed with an optical microscope or a CCD camera, and the chip arrangement and alignment marks formed on the front surface of the wafer 900 are observed. Then, positioning is performed based on the chip arrangement and alignment marks, and a dicing blade rotated at high speed is scanned over the wafer at a constant direction / interval, thereby cutting the wafer into individual chips.

  By the way, the wafer after the wafer thinning process has a very high added value, and in the process performed after the wafer thinning process, it is particularly desired to reduce defective wafers. For this reason, in order to suppress chipping and chipping at the wafer edge, and to correct warpage and deflection of the wafer, a rib structure wafer having a wafer outer peripheral portion thicker than the wafer inner peripheral portion is known. (For example, see Patent Document 1 below.) For rib-structured wafers, for example, the outer peripheral part of the wafer back surface is masked and then etched to thin only the wafer inner peripheral part, or only the wafer inner peripheral part is wheel-polished to thin only the wafer inner peripheral part. Obtained by.

  FIG. 10 is an explanatory view schematically showing an example of a dicing process for a rib structure wafer. The rib structure wafer 1000 has a large step (boundary between a thick outer peripheral portion and a thin inner peripheral portion) on the back surface (the surface on which the metal electrode film 1001 is formed). For this reason, as shown in FIG. 10, when the back surface of the rib structure wafer 1000 is bonded to the dicing tape 1010, a cavity 1020 is generated in the inner peripheral portion of the wafer. In addition, if the hollow portion 1020 is forcibly attached to the dicing tape 1010, a crack defect occurs in the rib structure wafer 1000. Furthermore, even if it is affixed, bubbles or gaps will enter between the dicing tape 1010 and the rib structure wafer 1000. If dicing is performed with air bubbles or gaps between the dicing tape 1010 and the rib structure wafer 1000, the dicing tape 1010 and the rib structure wafer 1000 are not fixed. The device will be scattered and the production efficiency will be reduced.

JP 2003-243356 A

  In order to prevent such a defect at the time of dicing, dicing processing is performed by a method as shown in FIG. 11 when dicing the rib structure wafer. FIG. 11 is an explanatory view schematically showing a dicing process for a rib structure wafer. In the example shown in FIG. 11, contrary to FIG. 10, dicing is performed by bonding the front surface side of the rib structure wafer 1100 and the dicing tape 1110 so that the wafer back surface with the rib step is on top. Thereby, it can bond together without producing a bubble and a clearance gap between the rib structure wafer 1100 and the dicing tape 1110. FIG.

  If a metal electrode film is not formed on the back surface of the rib structure wafer 1100, the infrared camera 1120 can be used to observe the chip arrangement and alignment marks on the front surface of the wafer and position the dicing line. This is because silicon of the semiconductor substrate transmits infrared rays. Thereby, contrary to a normal wafer (see FIG. 9), dicing can be normally performed even if a dicing tape is bonded to the front surface of the wafer and cut from the back side of the wafer.

  However, in the manufacturing method described above, when the metal electrode film is formed on the back surface of the rib structure wafer, there is a problem that the dicing line cannot be positioned because the metal electrode film does not transmit infrared rays.

  FIG. 12 is an explanatory view schematically showing a dicing process for a rib structure wafer on which a metal electrode film is formed. When the metal electrode film 1201 is formed on the back surface of the rib structure wafer 1200, the metal electrode film 1201 does not transmit infrared rays, so that the chip arrangement on the front side of the wafer can be observed even using the infrared camera 1220. I can't. For this reason, the dicing line cannot be positioned and dicing cannot be performed from the back surface of the wafer. Also, as shown in FIG. 10, when the rib structure wafer is diced from the front surface side, a crack defect or the like due to a rib step occurs and the production efficiency of the semiconductor device decreases. There is.

  An object of the present invention is to provide a method of manufacturing a semiconductor device and a marking device capable of efficiently dicing a rib structure wafer having a metal electrode film formed on the back surface in order to eliminate the above-described problems caused by the prior art. .

In order to solve the above-described problems and achieve the object, a manufacturing method of a semiconductor device according to claim 1 is provided on the first main surface of a semiconductor wafer in which an outer peripheral portion of the first main surface is thicker than other regions. A back surface electrode forming step for forming a metal electrode film, and a mark for adjusting the cutting position of the semiconductor wafer on the first main surface of the semiconductor wafer based on an image obtained by photographing the shape of the second main surface of the semiconductor wafer And a setting step for setting a dicing line based on the cutting position adjustment mark in this order, and in the marking step, the center positions of four adjacent chips on the outer peripheral portion of the semiconductor wafer There by adjusting the position of the semiconductor wafer such that the center of the image, the cutting position adjusting at least three places of the outer peripheral portion of the first main surface of the semiconductor wafer Forming a use marks, in the setting step, based on the interval dicing vertically and horizontally to a preset, the cutting position the starting point of the adjustment marks the dicing lines of the three, end point, it is parallel out point It is characterized by.

  According to the first aspect of the present invention, the cutting position adjusting mark can be formed at an appropriate position on the first main surface of the semiconductor wafer based on the shape of the second main surface of the semiconductor wafer.

According to a second aspect of the present invention, there is provided a manufacturing method of a semiconductor device according to the first aspect of the present invention, wherein the marking step uses the camera provided on the second main surface side of the semiconductor wafer. 2 The shape of the main surface side is photographed .

  According to the second aspect of the present invention, the cutting position adjustment mark is formed by observing the shape of the second main surface side of the semiconductor wafer from the image output from the camera provided on the second main surface side of the semiconductor wafer. Can be formed.

According to a third aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: a back electrode forming step of forming a metal electrode film on the first main surface of a semiconductor wafer having an outer peripheral portion of the first main surface thicker than other regions; An electrode film removing step of selectively removing the metal electrode film in a region to be an inspection chip out of the metal electrode film formed on the first main surface of the semiconductor wafer; and A marking step of forming a mark for adjusting the cutting position of the semiconductor wafer on the first main surface of the semiconductor wafer based on an image obtained by photographing the shape of the second main surface side of the removed region, and the adjustment of the cutting position seen including a setting step of setting a dicing line based on use marks and, in the marking process, so that the center position of the semiconductor wafer outer periphery four chips adjacent of the center of the image The position of the semiconductor wafer is adjusted to form the cutting position adjusting marks at least at three locations on the outer periphery of the first main surface of the semiconductor wafer, and in the setting step, dicing is performed in the vertical and horizontal directions set in advance. Based on the interval, the three cutting position adjustment marks are set as a dicing line start point, end point, and parallel point .

  According to the third aspect of the invention, the semiconductor wafer can be diced from the first main surface side based on the shape of the second main surface side of the semiconductor wafer.

According to a fourth aspect of the present invention, there is provided the method for manufacturing a semiconductor device according to the third aspect of the present invention, wherein the marking step uses an infrared camera provided on the first main surface side of the semiconductor wafer. The second main surface side is photographed .

  According to the fourth aspect of the present invention, the cutting position adjustment mark is observed by observing the shape of the second main surface side of the semiconductor wafer from the image output from the infrared camera provided on the first main surface side of the semiconductor wafer. Can be formed.

  According to a fifth aspect of the present invention, there is provided a semiconductor device manufacturing method according to any one of the first to fourth aspects, wherein in the marking step, a laser beam is applied to the first main surface of the semiconductor wafer. The irradiation mark of the laser beam is used as the cutting position adjusting mark.

  According to the fifth aspect of the present invention, the cutting position adjusting mark can be formed by irradiating the first main surface of the semiconductor wafer with laser light.

  According to a sixth aspect of the present invention, there is provided a semiconductor device manufacturing method according to any one of the first to fourth aspects, wherein, in the marking step, the metal electrode is formed on the first main surface of the semiconductor wafer. A member harder than the film is pressure-contacted, and a pressure-contact mark by the member is used as the cutting position adjusting mark.

  According to the sixth aspect of the present invention, the cutting position adjusting mark can be formed by pressing the hard member against the first main surface of the semiconductor wafer.

  According to a seventh aspect of the present invention, there is provided a semiconductor device manufacturing method according to any one of the first to fourth aspects, wherein, in the marking step, ink is attached to the first main surface of the semiconductor wafer. The ink is used as the cutting position adjustment mark.

  According to the seventh aspect of the present invention, the cutting position adjusting mark can be formed by attaching ink to the first main surface of the semiconductor wafer.

  According to an eighth aspect of the present invention, there is provided a method for manufacturing a semiconductor device according to any one of the first to seventh aspects, wherein the semiconductor device is formed using the cutting position adjusting mark formed in the marking step. It includes a cutting step of cutting the wafer into chips.

  According to the eighth aspect of the invention, the semiconductor wafer can be cut into chips based on the cutting position adjusting marks formed on the first main surface side of the semiconductor wafer.

The marking device according to the invention of claim 9 is characterized in that a mark is formed on the second main surface of the semiconductor wafer while photographing the first main surface of the semiconductor wafer where the outer peripheral portion of the first main surface is thicker than other regions. a marking apparatus for forming, wherein provided on the first main surface side of the semiconductor wafer, a photographing means for photographing the first major surface, provided on the second major surface side of said semiconductor wafer, said imaging means Marking means for forming the mark on the second main surface based on the image photographed by the method, and setting means for setting a dicing line based on the mark, the marking means comprising an outer periphery of the semiconductor wafer the center position of the four chips section adjacent is to adjust the position of the semiconductor wafer such that the center of the image, less of the outer peripheral portion of the first main surface of the semiconductor wafer Forming the mark Kutomo three, the setting means, based on the interval dicing vertically and horizontally, which is set in advance and the mark of the three starting points of the dicing line, the end point, parallel out point It is characterized by that.

  According to the ninth aspect of the present invention, the cutting position adjusting mark can be formed at an appropriate position on the second main surface of the semiconductor wafer based on the shape on the first main surface side of the semiconductor wafer.

  The marking device according to a tenth aspect of the present invention is the marking device according to the ninth aspect, wherein the marking means irradiates the second main surface of the semiconductor wafer with a laser beam, The mark is used.

  According to the tenth aspect of the present invention, the cutting position adjusting mark can be formed by irradiating the second main surface of the semiconductor wafer with the laser beam.

  The marking device according to an eleventh aspect of the present invention is the marking device according to the ninth aspect, wherein the marking means is a member harder than the surface layer of the second main surface on the second main surface of the semiconductor wafer. , And a mark of pressure contact by the member is used as the mark.

  According to the eleventh aspect of the present invention, the cutting position adjusting mark can be formed by pressing the hard member against the second main surface of the semiconductor wafer.

  The marking device according to a twelfth aspect of the present invention is the marking device according to the ninth aspect, wherein the marking means attaches ink to the second main surface of the semiconductor wafer and uses the ink as the mark. It is characterized by.

  According to the twelfth aspect of the present invention, the cutting position adjustment mark can be formed by attaching ink to the second main surface of the semiconductor wafer.

  According to the semiconductor device manufacturing method and the marking device of the present invention, the rib structure wafer having the metal electrode film formed on the back surface can be efficiently diced.

  Exemplary embodiments of a method for manufacturing a semiconductor device and a marking device according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment 1)
First, the structure of the semiconductor wafer used in the semiconductor device manufacturing method according to the first embodiment will be described. FIG. 1 is an explanatory view showing an example of the structure of a semiconductor wafer (rib structure wafer) used in the first embodiment. FIG. 1 illustrates the back surface of the rib structure wafer.

  A rib-structure wafer 100 shown in FIG. 1 has a substantially circular shape with a diameter of 150 mm (6 inches), for example, and an inner peripheral portion 101 and an outer peripheral portion 102 are formed on the back surface. The inner peripheral portion 101 is, for example, a circle having a radius of 60 mm to 74 mm. Further, the outer peripheral portion 102 is formed from the edge of the inner peripheral portion 101 to the outer peripheral end portion of the rib structure wafer 100. The inner peripheral portion 101 has a thickness of, for example, 50 μm, and the outer peripheral portion 102 has a thickness of, for example, 300 μm. The inner peripheral portion 101 is thinner than the outer peripheral portion 102.

  Here, an example of a manufacturing process of the rib structure wafer 100 will be described. First, a gate structure and a source / emitter structure are formed on the surface side of a thick wafer to form a surface element structure portion. Next, the wafer outer peripheral portion is masked and only the wafer inner peripheral portion is etched to reduce the thickness of the wafer inner peripheral portion. Alternatively, only the wafer inner peripheral portion may be wheel-polished to reduce the thickness of the wafer inner peripheral portion. Then, a metal electrode film is formed on the back surface of the thinned wafer. As a material of the metal electrode film, for example, aluminum (Al), titanium (Ti), nickel (Ni), gold (Au), or the like can be laminated and used. The rib structure wafer 100 is formed by the procedure as described above.

  Thereafter, the rib structure wafer 100 is diced to form individual chips. More specifically, while observing the shape of the front surface side of the rib structure wafer 100, that is, based on the arrangement of the surface element structure portions formed on the front surface side, the dicing line is positioned, An alignment mark serving as a reference point during dicing is added to the back surface of the rib structure wafer 100. A dicing blade rotated at high speed is scanned over the wafer at a constant direction / interval, and the wafer is cut into individual chips.

  Next, a marking device 200 used for forming an alignment mark on the rib structure wafer 100 will be described. FIG. 2 is a perspective view showing an appearance of the marking device used in the first embodiment. The marking device 200 includes an XY stage 201, an X-axis adjustment screw 202, a Y-axis adjustment screw 203, a Z-axis adjustment screw 204, a CCD camera 205, and a laser marker 206.

  The XY stage 201 can be moved in the X axis direction, the Y axis direction, and the Z axis direction by an X axis adjustment screw 202, a Y axis adjustment screw 203, and a Z axis adjustment screw 204, respectively. A laser marker 206 is provided on the upper surface side of the XY stage 201, and a CCD camera 205 is provided on the lower surface side. The central portion of the XY stage 201 is provided with an opening 210, which enables photographing of the lower surface side of an object (specifically, the rib structure wafer 100) placed on the XY stage 201 by the CCD camera 205. Note that an object placed on the XY stage 201 may be photographed with the CCD camera 205 by creating the XY stage 201 with a transparent material such as glass without providing the opening 210.

  The CCD camera 205 photographs the lower surface side of the object placed on the XY stage 201 and outputs the image as an image signal to a monitor (not shown). The laser marker 206 irradiates laser light generated by a laser oscillator (not shown) onto the upper surface side of the object placed on the XY stage 201, and forms a mark by making an irradiation mark on the object surface. Laser irradiation from the laser marker 206 is controlled by a switch 207, for example.

  When marking is performed by the marking device 200, the center of the optical axis of the CCD camera 205 and the laser irradiation position of the laser marker 206 are matched in advance. In the example shown in FIG. 2, the CCD camera 205 and the laser marker 206 are fixed in advance at positions where the optical axis center and the laser irradiation position coincide.

  When the position of the center of the optical axis of the CCD camera 205 or the laser irradiation position of the laser marker 206 can be moved, for example, while irradiating laser from the laser marker 206 without placing an object on the XY stage 201, the CCD camera The laser spot reflected in the image output from 205 is observed. Then, the position of the CCD camera 205 or the laser marker 206 is adjusted so that the laser spot becomes the center of the image output from the CCD camera 205. Thereby, the center of the optical axis of the CCD camera 205 and the laser irradiation position of the laser marker 206 can be matched.

  When marking is performed by the marking device 200, an object is placed on the XY stage 201, and the X-axis adjusting screw 202 and the Y-axis adjusting screw 203 are adjusted while viewing an image on the lower surface side of the object imaged by the CCD camera 205, and desired. The position of (the point you want to mark) is set to the center of the image. If necessary, the position of the XY stage 201 in the Z-axis direction is adjusted by the Z-axis adjusting screw 204 so that the CCD camera 205 is focused on the lower surface of the object. Then, laser is irradiated from the laser marker 206 at that position, and marking is performed on the upper surface side of the object. Thereby, a mark can be added to a desired position.

  Next, an alignment mark forming process for the rib structure wafer 100 will be described. FIG. 3 is an explanatory view schematically showing an alignment mark forming process for the rib structure wafer. When forming the alignment mark on the rib structure wafer 100, the rib structure wafer 100 is placed on the XY stage 201 with the back surface of the rib structure wafer 100 facing the laser marker 206 and the front surface of the rib structure wafer 100 facing the CCD camera 205. That is, the surface with the rib structure step is placed on the upper surface side of the XY stage 201, and the surface on which the surface element structure is formed is placed on the lower surface side of the XY stage 201.

  The CCD camera 205 images the front side of the rib structure wafer 100 mounted on the XY stage 201 and outputs an image signal to the monitor 230. The monitor 230 displays an image of the front surface side of the rib structure wafer 100 taken by the CCD camera 205. The X-axis adjusting screw 202 and the Y-axis adjusting screw 203 are adjusted while viewing the image of the front surface of the rib structure wafer 100 displayed on the monitor 230, and the desired position (the point where marking is desired) is imaged. To be the center of

Specifically, for example, as shown in FIG. 3, the center position P of the adjacent chips C1 to C4 of the surface element structure portion is adjusted to be the center of the image. For example, when an alignment mark is formed in advance on the front surface of the rib structure wafer 100, the position is adjusted so as to be the center of the image. Then, a laser is irradiated from the laser marker 206 at that position, and an alignment mark (irradiation trace) for adjusting the cutting position is formed on the metal electrode film on the back surface side of the rib structure wafer 100. At this time, for example, a YLF2ω laser or a YAG2ω laser can be used as the type of laser emitted from the laser marker 206. The laser irradiation energy density is, for example, 0.2 to 4.0 J / cm ² .

  FIG. 4 is an explanatory view schematically showing the relationship between the alignment mark for adjusting the cutting position on the wafer and the dicing line. The chip size, that is, the distance between dicing vertically and horizontally (x and y in FIG. 4) is known. Therefore, if the alignment marks are formed at least at three points in the wafer (start point, end point, parallel projection points: M1 to M3 in FIG. 4), the rib structure wafer 100 can be parallelized / vertically aligned. A dicing line can be set. The alignment mark may be added to the outer peripheral portion of the rib structure wafer 100.

  After adding the alignment mark as described above, a dicing process is performed in which the rib structure wafer 100 is diced from the back surface side to form individual chips. A dicing tape and a dicing frame are attached to the front surface of the rib structure wafer 100. In the case of a normal semiconductor wafer, a dicing tape and a dicing frame are attached to the back surface of the wafer. However, the rib structure wafer 100 has a rib step on the back surface, which is opposite to the normal attachment surface. Then, positioning is performed using the alignment mark formed by the marking device 200 as a reference, and the rib structure wafer 100 is diced from the back side using a normal dicing device.

  In the above description, the position of the alignment mark is determined while viewing the image displayed on the monitor. However, the present invention is not limited to this. For example, the image signal output from the CCD camera 205 may be output to a computer, the image signal may be analyzed by the computer, and the position of the XY stage 201 may be controlled by the computer to determine the position of the alignment mark.

  In the above description, the marking device 200 performs marking with the laser marker 206, but the present invention is not limited to this. For example, the marking may be performed by pressure contact with a hard member.

  FIG. 5 is a diagram schematically showing another configuration example of the marking device. In the marking device 500 having the configuration shown in FIG. 5, a pressure core rod 240 made of a hard member is used instead of the laser marker 206. The marking device 500 performs the marking for adjusting the cutting position by bringing the pressure core rod 240 into pressure contact with the back surface of the rib structure wafer 100 and forming an impression (dent) on the metal electrode film.

  In this case, for example, the center of the optical axis of the CCD camera 205 and the pressure contact position by the pressure core rod 240 are matched in advance. Then, an image on the lower surface side of the object imaged by the CCD camera 205 is displayed on the monitor 230 so that a desired position (a point to be marked) becomes the center of the image. Then, the pressure core rod 240 is adjusted in the Z-axis direction at that position and pressed against the back surface of the rib structure wafer 100 to form a pressure contact mark.

  As a material of the pressure core rod 240, for example, a material harder than the metal electrode film, such as diamond, ceramic, or silicon, is desirable. The tip shape of the pressure core rod 240 may be formed in accordance with a desired indentation shape such as a cross (+), a circle (◯), or a square (□).

  The pressure contact with the pressure core rod 240 may cause mechanical damage not only on the metal electrode film of the rib structure wafer 100 but also on the underlying silicon surface. However, since the alignment mark is in the scribe region, the damaged portion is also removed at the time of dicing if the damage is slight. For this reason, it does not become a trouble also in a subsequent process.

  In addition, for example, marking for adjusting the cutting position may be performed by attaching ink onto the metal electrode film on the back surface side of the rib structure wafer 100. FIG. 6 is a diagram schematically showing another configuration example of the marking device. In the marking device 600 having the configuration shown in FIG. 6, an ink application member 250 having an ink application part 251 such as a pen tip of an ink marker or an ink discharge port is used instead of the laser marker 206. Specifically, the marking is performed by adjusting the ink application member 250 in the Z-axis direction and applying ink to the back surface of the rib structure wafer 100 by the ink application part 251.

  When using the ink application member 250, for example, the center of the optical axis of the CCD camera 205 and the ink application position by the ink application part 251 are matched in advance. The X-axis adjusting screw 202 and the Y-axis adjusting screw 203 are adjusted while viewing the image on the lower surface side of the object imaged by the CCD camera 205, and the desired position (the point where marking is desired) becomes the center of the image. Like that. Then, the ink application member 250 is adjusted in the Z-axis direction at that position, and ink is applied to the back surface of the rib structure wafer 100 to place an alignment mark. In this case, ink applied as an alignment mark by dicing is removed, so that there is no influence on the chip after dicing.

  The material of the ink applied by the ink application member 250 is not particularly limited as long as a sufficient contrast can be formed when observed with a CCD camera 205 or an optical microscope. Ink or the like can be used. This is because the wafer process of the rib structure wafer 100 is completed and a protective film is formed.

  As described above, according to the marking method according to the first embodiment, the alignment mark for adjusting the cutting position corresponding to the shape of the wafer surface, that is, the chip arrangement and the alignment mark, is formed on the wafer back surface of the rib structure wafer. . Then, a wafer can be diced from the back surface side by attaching a dicing tape to the front surface of the wafer and positioning based on the alignment mark formed on the back surface of the wafer. As a result, there are no gaps or bubbles between the wafer and the dicing tape, as in the case of dicing with a dicing tape attached to the back of the rib structure wafer, reducing chip defects and crack defects during dicing. Can be made.

  In addition, according to the method for manufacturing a semiconductor device according to the first embodiment, the alignment mark for adjusting the cutting position can be efficiently formed by a simple process. As a method of forming the alignment mark, for example, a method of performing marking by applying a photoresist on the back surface of the wafer and etching a part of the metal electrode film using a double-sided aligner can be considered. In this method, since a large number of marks can be formed at a time, it is efficient when a large number of marks need to be formed. However, a photo process such as resist coating, exposure, development, and baking is added, which increases costs and lead time. When forming alignment marks for dicing as in this embodiment, it is only necessary to form three marks on a semiconductor wafer as shown in FIG. For this reason, it is more efficient to form by a method like this embodiment rather than using a double-sided aligner.

  In the method for manufacturing a semiconductor device according to the first embodiment, dicing is performed by attaching a dicing tape to the front surface of the wafer. For this reason, it is possible to prevent dicing cutting waste (silicon powder) from adhering to the device surface. During normal dicing, dicing tape is attached to the back surface of the wafer, so that cutting waste adheres to the wafer surface. In order to remove the cutting waste, cleaning is performed by spraying a high-pressure water stream. However, in the case of a device having a complicated step structure, removal of cutting waste is particularly difficult, and a large amount of cleaning water and cleaning time are required. In the manufacturing method of the semiconductor device according to the first embodiment, since the dicing tape is bonded to the wafer surface, cutting waste does not adhere to the device surface. Moreover, although cutting waste adheres to the back surface of the wafer, the back surface of the wafer is smoother than the front surface, so that the cutting waste can be easily removed, and the amount of cleaning water and cleaning time during cleaning can be reduced.

(Embodiment 2)
In the first embodiment, the dicing line is positioned by observing the surface element structure portion of the rib structure wafer 100 with the CCD camera 205. In the second embodiment to be described next, a part of the metal electrode film formed on the back surface of the rib structure wafer 100 is removed, and the surface element structure portion is observed with an infrared camera from the removed portion, and the dicing line is positioned. To do. In the second embodiment, the description will be made assuming that the rib structure wafer 100 shown in FIG. 1 is used as in the first embodiment.

  FIG. 7 is an explanatory view schematically showing the method of manufacturing the semiconductor device according to the second embodiment. In the method of manufacturing a semiconductor device according to the second embodiment, first, a metal electrode film in a region where a PCM (process control monitor) chip is formed is selected from the metal electrode films formed on the back surface of the rib structure wafer 100. Then, the openings L are formed.

  The PCM chip is a chip on which a simple device for monitoring whether or not a product being manufactured is within a standard range without any abnormality or defect in a semiconductor chip manufacturing process is formed. The PCM chip is often used for electrical measurement (inspection) performed after completion of the wafer process, and has finished its role during wafer dicing. For this reason, if the metal electrode film on the back surface of the normal chip is removed, a chip loss occurs. However, even if the metal electrode film on the back surface of the PCM chip is removed, no chip loss occurs.

  Three to five PCM chips are formed on a semiconductor wafer. The positions where the PCM chips are formed are determined in advance, and the PCM chips are formed at intervals. For this reason, alignment is easy when the PCM chip is used as a reference.

  When removing the metal electrode film on the back surface of the PCM chip, for example, a nozzle for dropping etching droplets is aligned with the back surface at the position where the PCM chip is formed, and several drops of the metal film etching solution are dropped from the nozzle. At this time, the dropping amount of the metal film etching solution is adjusted by the dispenser so that the etching solution does not protrude from the PCM chip area and enter the product chip area. This is because if the metal film etching solution enters the region of the product chip, the product chip is lost. Then, after the metal electrode film is dissolved, the metal film etching solution is wiped off to form the opening L. Further, for example, etching may be performed by masking a region other than the PCM chip, and after etching only the region of the PCM chip, the mask may be removed.

  Thereafter, using the infrared camera C from the opening L, the shape of the front surface side of the rib structure wafer 100, that is, the chip arrangement of the surface element structure portion, is observed, and the dicing line is positioned. Even if the opening L is smaller than the size of the PCM chip, the chip size is determined, so that a dicing line can be set if the position of the opening L on the PCM chip is known. The procedure of the subsequent dicing process is as described in the first embodiment. As in the first embodiment, the alignment mark for adjusting the cutting position is formed on the back surface while observing the shape of the front surface side of the rib structure wafer, and the dicing process is performed based on this mark. Also good.

  Next, a modification of the semiconductor device manufacturing method according to the second embodiment will be described. FIG. 8 is an explanatory view schematically showing a modification of the method for manufacturing the semiconductor device according to the second embodiment. In the modification shown in FIG. 8, the metal electrode film on the back surface of the wafer outer peripheral region S where the product chip is not formed is selectively removed. Specifically, after forming an etching protective film on the front surface of the rib structure wafer 100, the outer peripheral region S of the rib structure wafer is immersed in a metal film etching solution (for example, aqua regia) to form a metal electrode film. Remove.

  After the metal electrode film in the outer peripheral region S is removed, for example, when an alignment mark is formed in advance on the front surface of the outer peripheral region S of the rib structure wafer 100, Observe the position and shape, and position the dicing line. The procedure of the subsequent dicing process is as described in the first embodiment.

  Further, for example, dummy chips may be formed in accordance with the arrangement of the product chips on the outer periphery of the wafer on which the product chips are not formed and used for positioning. In FIG. 8, the dotted line on the rib structure wafer 100 indicates the position of the product chip formed on the front surface side. A thick line on the rib structure wafer 100 indicates the position of the dummy chip formed on the front surface side. In this case, the dicing line is positioned by observing the shape of the arrangement of dummy chips on the front surface side by the infrared camera C from the back surface of the rib structure wafer 100 from which the metal electrode film has been removed.

  As described above, according to the manufacturing method of the semiconductor device according to the second embodiment, a part of the metal electrode film formed on the back surface of the rib structure wafer is removed, and the chip array and the alignment mark on the wafer surface are removed. The dicing line can be positioned by observing. The wafer can be diced by attaching a dicing tape to the wafer surface. This eliminates gaps and bubbles between the wafer and the dicing tape, as in the case of dicing with a dicing tape attached to the back of the rib structure wafer, and reduces chip defects and crack defects. Can do.

  Further, in the method of manufacturing a semiconductor device according to the second embodiment, dicing is performed by attaching a dicing tape to the wafer surface as in the first embodiment. For this reason, it can prevent that the cutting waste of dicing adheres to a device surface, and can reduce the amount of washing water at the time of washing of cutting waste, and washing time.

  As described above, the method for manufacturing a semiconductor device and the marking device according to the present invention are useful when a semiconductor device having a metal electrode film on the back surface is manufactured using a wafer having a rib structure. Suitable for manufacturing vertical MOSFETs.

FIG. 3 is an explanatory diagram showing an example of a structure of a semiconductor wafer used in the first embodiment. It is a perspective view which shows the external appearance of the marking apparatus used in Embodiment 1. FIG. It is explanatory drawing which showed typically the alignment mark formation process with respect to a rib structure wafer. It is explanatory drawing which shows typically the relationship between the alignment mark for cutting position adjustment on a wafer, and a dicing line. It is the figure which showed typically the other structural example of the marking apparatus. It is the figure which showed typically the other structural example of the marking apparatus. FIG. 6 is an explanatory view schematically showing a method for manufacturing a semiconductor device according to a second embodiment; FIG. 10 is an explanatory view schematically showing a modification of the method for manufacturing a semiconductor device according to the second embodiment. It is explanatory drawing which shows typically the dicing process with respect to a wafer. It is explanatory drawing which shows typically an example of the dicing process with respect to a rib structure wafer. It is explanatory drawing which shows typically the dicing process with respect to a rib structure wafer. It is explanatory drawing which shows typically the dicing process with respect to the rib structure wafer in which the metal electrode film was formed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Rib structure wafer 101 Inner peripheral part 102 Outer peripheral part 200 Marking apparatus 201 XY stage 202 X-axis adjustment screw 203 Y-axis adjustment screw 204 Z-axis adjustment screw 205 CCD camera 206 Laser marker 207 Switch 210 Opening part 230 Monitor

Claims (12)

A back electrode forming step of forming a metal electrode film on the first main surface of the semiconductor wafer in which the outer peripheral portion of the first main surface is thicker than other regions;
A marking step of forming a mark for adjusting the cutting position of the semiconductor wafer on the first main surface of the semiconductor wafer based on an image obtained by photographing the shape of the second main surface of the semiconductor wafer;
A setting step for setting a dicing line based on the cutting position adjustment mark;
In this order,
In the marking step, the position of the semiconductor wafer is adjusted so that the center position of four adjacent chips on the outer periphery of the semiconductor wafer is the center of the image, and the outer periphery of the first main surface of the semiconductor wafer is adjusted. part forming the cutting position adjustment mark in at least three locations,
In the setting step, the cutting position adjusting marks at the three positions are set as a dicing line start point, end point, and parallel projecting point based on a predetermined interval between vertical and horizontal dicing. Manufacturing method. 2. The method of manufacturing a semiconductor device according to claim 1, wherein in the marking step, the shape of the second main surface is photographed using a camera provided on the second main surface of the semiconductor wafer. . A back electrode forming step of forming a metal electrode film on the first main surface of the semiconductor wafer in which the outer peripheral portion of the first main surface is thicker than other regions;
An electrode film removing step of selectively removing the metal electrode film in a region to be an inspection chip from the metal electrode film formed on the first main surface of the semiconductor wafer;
A marking step of forming a cutting position adjusting mark of the semiconductor wafer on the first main surface of the semiconductor wafer based on an image of the shape of the second main surface side of the region from which the metal electrode film has been removed; ,
A setting step for setting a dicing line based on the cutting position adjustment mark;
Only including,
In the marking step, the position of the semiconductor wafer is adjusted so that the center position of four adjacent chips on the outer periphery of the semiconductor wafer is the center of the image, and the outer periphery of the first main surface of the semiconductor wafer is adjusted. Forming the cutting position adjusting marks in at least three locations of the part,
In the setting step, the cutting position adjusting marks at the three positions are set as a dicing line start point, end point, and parallel projecting point based on a predetermined interval between vertical and horizontal dicing. Manufacturing method. 4. The manufacturing of a semiconductor device according to claim 3, wherein in the marking step, the shape of the second main surface side is photographed using an infrared camera provided on the first main surface side of the semiconductor wafer. Method.   In the marking step, the first main surface of the semiconductor wafer is irradiated with a laser beam, and an irradiation mark of the laser beam is used as the cutting position adjusting mark. The manufacturing method of the semiconductor device as described in one.   2. In the marking step, a member harder than the metal electrode film is pressed against the first main surface of the semiconductor wafer, and a pressure contact mark by the member is used as the cutting position adjusting mark. The manufacturing method of the semiconductor device as described in any one of -4.   5. The semiconductor according to claim 1, wherein in the marking step, ink is attached to the first main surface of the semiconductor wafer, and the ink is used as the cutting position adjustment mark. Device manufacturing method.   8. The semiconductor device according to claim 1, further comprising a cutting step of cutting the semiconductor wafer into chips using the cutting position adjusting marks formed in the marking step. Manufacturing method. A marking device for forming a mark on the second main surface of the semiconductor wafer while photographing the first main surface of the semiconductor wafer, wherein the outer peripheral portion of the first main surface is thicker than other regions,
Provided on the first main surface side of said semiconductor wafer, a photographing means for photographing the first main surface,
Marking means provided on the second main surface side of the semiconductor wafer and forming the mark on the second main surface based on an image photographed by the photographing means;
Setting means for setting a dicing line based on the mark;
With
The marking means adjusts the position of the semiconductor wafer so that the center position of four adjacent chips on the outer peripheral portion of the semiconductor wafer becomes the center of the image, and the outer periphery of the first main surface of the semiconductor wafer said mark formed on at least three parts,
The marking device according to claim 1, wherein the setting unit sets the three marks as a starting point, an ending point, and a paralleling point of the dicing line based on preset vertical and horizontal dicing intervals .   The marking device according to claim 9, wherein the marking unit irradiates the second main surface of the semiconductor wafer with a laser beam and uses an irradiation mark of the laser beam as the mark.   10. The marking device according to claim 9, wherein the marking means presses a member harder than the semiconductor wafer against the second main surface of the semiconductor wafer, and uses a press contact mark by the member as the mark. .   The marking device according to claim 9, wherein the marking unit attaches ink to the second main surface of the semiconductor wafer and uses the ink as the mark.

Images