WO2013011548A1 - 半導体装置の製造方法 - Google Patents
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- WO2013011548A1 WO2013011548A1 PCT/JP2011/066262 JP2011066262W WO2013011548A1 WO 2013011548 A1 WO2013011548 A1 WO 2013011548A1 JP 2011066262 W JP2011066262 W JP 2011066262W WO 2013011548 A1 WO2013011548 A1 WO 2013011548A1
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- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
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Definitions
- the present invention relates to a method of manufacturing a semiconductor device.
- IGBTs Insulated Gate Bipolar Transistors
- MOSFETs Metal Oxide Semiconductor Field Effect Transistors
- a one-chip power device having a low on-voltage characteristic of a bipolar transistor.
- the application range is expanding from industrial fields such as general-purpose inverters, AC servos, uninterruptible power supplies (UPSs) or switching power supplies to consumer electronics fields such as microwave ovens, rice cookers or strobes.
- FIG. 11 is a cross-sectional view showing the main parts of the configuration of the reverse blocking IGBT.
- FIG. 11 shows a cross-sectional structure in the vicinity of the breakdown voltage structure portion 110 of the reverse blocking IGBT 100.
- the reverse blocking IGBT 100 includes an active region (not shown), a withstand voltage structure unit 110 for holding a withstand voltage, and a separation structure unit 120 for holding a reverse withstand voltage.
- the pressure resistant structure 110 surrounds the active region, and the isolation structure 120 surrounds the pressure resistant structure 110.
- the MOS gate structure and the emitter electrode (not shown) of the IGBT are formed on the first main surface (front surface) of the semiconductor substrate 101 to be an n-type drift region.
- a p-type field limiting ring 111 and a p-type channel stopper 112 are formed on the surface layer of the first main surface of the semiconductor substrate 101.
- the p-type channel stopper 112 is formed on the element end side of the withstand voltage structure 110.
- a conductive film 113 is connected to each of the p-type field limiting ring 111 and the p-type channel stopper 112.
- the conductive films 113 are mutually insulated by the interlayer insulating film 114.
- a p-type collector layer 102 is formed on the surface layer of the second main surface (rear surface) of the semiconductor substrate 101 from the active region to the breakdown voltage structure portion 110. Then, in order to maintain the reverse breakdown voltage of reverse blocking IGBT 100, p-type collector layer 102 provided on the second main surface side of semiconductor substrate 101 and p provided on the first main surface side of semiconductor substrate 101. The mold channel stopper 112 needs to be connected. Therefore, a p-type isolation region 121 in contact with the p-type collector layer 102 and the p-type channel stopper 112 is formed in the isolation structure portion 120 at the element end of the semiconductor substrate 101.
- the p-type isolation region 121 can be formed, for example, as a diffusion layer having the same depth as the thickness of the semiconductor substrate 101 by deep diffusion reaching from the first main surface side of the semiconductor substrate 101 to the second main surface.
- the diffusion layer to be the p-type isolation region 121 is formed as described above, it is necessary to form the diffusion layer at a depth corresponding to the thickness of the n-type drift region for each breakdown voltage class.
- the depth of the diffusion layer to be the p-type isolation region 121 needs to be 120 ⁇ m or more in the reverse blocking IGBT of 600 V withstand voltage class and 200 ⁇ m or more in the reverse blocking IGBT of 1200 V withstand voltage class.
- heat treatment needs to be performed at a temperature of 1300 ° C. for 100 hours or more.
- the depth from the first main surface side of semiconductor substrate 101 to groove 130 formed in the second main surface is shallower than the thickness of semiconductor substrate 101.
- a reverse blocking IGBT 100 is known in which the p-type collector layer 102 and the p-type channel stopper 112 are connected by the p-type isolation region 121 and the p-type layer 131 formed on the side wall of the groove 130.
- the reverse blocking IGBT 100 is provided with a deep diffusion layer extending from the first main surface side of the semiconductor substrate 101 to the second main surface.
- a reverse breakdown voltage comparable to that of the reverse blocking IGBT can be obtained.
- the reverse blocking IGBT 100 is manufactured (manufactured), for example, as follows. First, the p-type isolation region 121 is formed at a predetermined depth not reaching the second major surface from the first major surface side of the semiconductor substrate 101. Next, on the first main surface of the semiconductor substrate 101, a front surface element structure such as a MOS gate structure or an emitter electrode and a front surface element structure of the breakdown voltage structure portion 110 are formed. The p-type channel stopper 112 formed as the front surface element structure of the breakdown voltage structure portion 110 is formed in contact with the p-type isolation region 121.
- a groove 130 reaching the p-type isolation region 121 from the side of the second main surface of the semiconductor substrate 101 is formed.
- the groove 130 is formed to surround the pressure resistant structure 110.
- the p-type collector layer 102 is formed on the surface layer of the second main surface of the semiconductor substrate 101, and the p-type layer is in contact with the p-type collector layer 102 and the p-type isolation region 121 on the surface layer of the sidewall portion of the groove 130.
- Form 131 Thereafter, a collector electrode (not shown) in contact with the p-type collector layer 102 and the p-type layer 131 is formed.
- Such reverse blocking IGBT 100 is formed in each element formation region of the wafer.
- the groove 130 is formed on a dicing line surrounding the element formation region of the wafer. Then, the wafer is diced along the groove 130 using a dicing blade having a width smaller than the width in the short direction of the bottom surface of the groove 130, and the plurality of reverse blocking IGBTs 100 formed on the wafer are cut into chips. . Thereby, the reverse blocking IGBT 100 is completed.
- a positive bevel structure is formed outside the planar breakdown voltage structure of the IGBT.
- a forward breakdown voltage is provided by the planar pressure structure and a reverse breakdown voltage is provided by the positive bevel structure.
- FIG. 12 is an explanatory view showing the state of a wafer in the process of manufacturing a conventional semiconductor device.
- a planar layout of the groove 130 formed in the second main surface of the wafer 200 is shown by a dotted line.
- the cross-sectional structure of the wafer 200 cut along the cutting lines AA-AA 'and BB-BB' is shown at the center and the lower side of FIG.
- the cross section cut along the cutting line AA-AA ' has a cross-sectional structure in which the groove 130 is cut across the plurality of element forming regions 201 in the short direction.
- the cross section cut along the cutting line BB-BB ' is a cross-sectional structure in which the groove 130 is cut in the longitudinal direction.
- reverse blocking IGBTs are formed in the respective element formation regions 201 of the wafer 200, whereby grooves 130 are formed in a lattice on the second main surface of the wafer 200.
- the groove 130 is formed to reach the outer peripheral end (side surface) 202 of the wafer 200.
- grooves 130 are formed on the second main surface of wafer 200 at regular intervals, and the outer peripheral edge of the second main surface of wafer 200 It is not formed in the portions 202-1a and 202-2a.
- groove 130 is formed from outer peripheral end 202-1b of the second main surface of wafer 200 to the other outer peripheral end 202-2b.
- the thickness of the wafer 200 is uniformly reduced.
- Patent Document 2 A proposed method has been proposed (see, for example, Patent Document 2 below).
- a product chip area located in an effective processing area of a semiconductor wafer and in which a product chip constituting a semiconductor integrated circuit device is formed, and an outer peripheral portion of the semiconductor wafer, the product chip
- a conductive film is deposited on the surface of the insulating film including the inner surface of the recessed portion and the pseudo recessed portion, and the conductive film is polished by a CMP method to form the conductive film on the surface of the insulating film.
- An object of the present invention is to provide a method of manufacturing a semiconductor device capable of reducing a crack in a semiconductor wafer in order to solve the above-mentioned problems of the prior art.
- a method of manufacturing a semiconductor device has the following features. First, on a first main surface of a semiconductor wafer of a first conductivity type, a MOS gate structure and a first electrode consisting of a gate electrode of a semiconductor element, a breakdown voltage structure for holding a breakdown voltage of the semiconductor element, and the semiconductor element And forming a first semiconductor region of a second conductivity type surrounding the breakdown voltage structure. Next, a step of forming a trench from the second main surface of the semiconductor wafer to the first semiconductor region is performed.
- a second conductivity type second semiconductor region is formed on the second main surface of the semiconductor wafer, and a second conductivity electrically contacting the first semiconductor region and the second semiconductor region on the sidewall of the groove
- a step of forming a third semiconductor region of the mold is performed.
- a step of forming a second electrode electrically in contact with the second semiconductor region is performed.
- the semiconductor wafer is left inside with a predetermined width from the outer peripheral end of the semiconductor wafer, and the groove is formed inside the semiconductor wafer than the outer peripheral end of the semiconductor wafer.
- the groove in the step of forming the groove, is formed so as to leave a distance of 7 mm or more from the sidewall of the groove to the outer peripheral end of the semiconductor wafer. It is characterized by forming.
- the cross-sectional shape of the groove is trapezoidal or circular.
- the thickness of the semiconductor wafer in a portion corresponding to the bottom of the groove is partially thickened. A groove is formed.
- the groove is formed so as to surround the semiconductor element and the withstand voltage structure portion.
- the groove when forming a groove surrounding the semiconductor element and the pressure-resistant structure portion formed in the wafer in the wafer, the groove does not reach the end in the longitudinal direction of the groove to the outer peripheral end of the wafer Form Therefore, it is possible to reduce the occurrence of cracks in the wafer during wafer processing, wafer transfer, and wafer handling.
- FIG. 1 is an explanatory view showing a state of a wafer in the process of manufacturing the semiconductor device according to the first embodiment.
- FIG. 2 is a cross-sectional view showing the cross-sectional shape of the groove according to the first embodiment.
- FIG. 3 is a cross-sectional view showing the cross-sectional shape of the groove according to the second embodiment.
- FIG. 4 is a cross-sectional view showing the cross-sectional shape of the groove according to the third embodiment.
- FIG. 5 is a cross-sectional view showing the state of the groove in the process of manufacturing the semiconductor device according to the third embodiment.
- FIG. 6 is a plan view showing the state of the wafer in the process of manufacturing the semiconductor device according to the third embodiment.
- FIG. 7 is a plan view showing a planar shape of a groove according to the fourth embodiment.
- FIG. 8 is a plan view showing another example of the planar shape of the groove according to the fourth embodiment.
- FIG. 9 is a characteristic diagram showing the crack occurrence rate of the wafer.
- FIG. 10 is a cross-sectional view schematically showing an end shape of a wafer outer peripheral end according to the embodiment.
- FIG. 11 is a cross-sectional view showing the main parts of the configuration of the reverse blocking IGBT.
- FIG. 12 is an explanatory view showing the state of a wafer in the process of manufacturing a conventional semiconductor device.
- n and p in the layer or region having n or p, it is meant that electrons or holes are majority carriers, respectively.
- + and-attached to n and p mean that the impurity concentration is higher and the impurity concentration is lower than that of the layer or region to which it is not attached, respectively.
- FIG. 1 is an explanatory view showing a state of a wafer in the process of manufacturing the semiconductor device according to the first embodiment.
- a plan view of the wafer 10 in a state in which the semiconductor device is formed is shown on the upper side of FIG.
- the cross section of the wafer 10 cut along the cutting line AA ′ is a cross sectional structure in which the groove 3 is cut across the plural element forming regions 1 in the short direction (the cross sectional view in the center of FIG. ).
- the cross section of the wafer 10 cut along the cutting line BB ′ is a cross sectional structure in which the groove 3 is cut in the longitudinal direction (a cross sectional view on the lower side of FIG. 1).
- FIG. 2 is a cross-sectional view showing the cross-sectional shape of the groove according to the first embodiment.
- each element formation region 1 of the wafer 10 an element structure (not shown) of a semiconductor device is formed.
- the semiconductor device formed on the wafer 10 is, for example, an IGBT (reverse blocking IGBT) having a reverse breakdown voltage (see FIG. 11).
- the reverse blocking IGBT includes an active region through which current flows when in the on state, a withstand voltage structure portion for holding a withstand voltage, and a separation structure portion for holding a reverse withstand voltage. That is, the active region, the breakdown voltage structure portion, and the isolation structure portion are formed in each element formation region 1.
- a MOS comprising a base region, an emitter region, a gate insulating film, and a gate electrode
- a front surface element structure of an IGBT is formed, such as a gate structure and an emitter electrode (first electrode).
- the pressure resistant structure is formed to surround the active region.
- a front surface element structure of a withstand voltage structure portion such as a p-type field limiting ring and a p-type channel stopper is formed on the surface layer of the first main surface of wafer 10.
- Ru is formed on the element end side of the breakdown voltage structure apart from the p-type field limiting ring.
- a conductive film is connected to each of the p-type field limiting ring and the p-type channel stopper. Each conductive film is mutually insulated by the interlayer insulation film.
- the isolation structure portion is formed on the element end side of each element formation region 1 so as to surround the breakdown voltage structure portion.
- the surface layer of the first main surface of wafer 10 holds the reverse breakdown voltage of the reverse blocking IGBT at a predetermined depth not reaching the second main surface of wafer 10.
- a p-type isolation region (first semiconductor region) is formed.
- the p-type isolation region is formed by diffusion by ion implantation and heat treatment, for example.
- the p-type isolation region is formed in contact with the p-type channel stopper.
- the wafer 10 is formed with the front surface element structure of the reverse blocking IGBT, the front surface element structure of the breakdown voltage structure portion and the separation structure portion on the first main surface side as described above, It is thinned from the main surface (back side) side.
- a groove 3 reaching the p-type separation region is formed on the second main surface of the thinned wafer 10.
- the groove 3 is formed so as not to reach the outer peripheral end (side surface) 2 of the second main surface of the wafer 10. That is, the groove 3 is formed so as not to penetrate in the lateral direction of the wafer (the direction perpendicular to the depth direction of the device). Further, the groove 3 is formed, for example, on a dicing line surrounding the element formation region 1 of the wafer 10 so as to surround the active region and the pressure-resistant structure portion.
- the groove 3 is formed, for example, by wet etching or dry etching using the resist mask formed on the second main surface of the wafer 10 as a mask. Further, the groove 3 is formed inside the outer peripheral end of the wafer 10 so as to leave the wafer 10 with a predetermined width inside from the outer peripheral end 2 of the wafer 10. That is, the groove 3 is formed such that the longitudinal end of the groove 3 does not reach the outer peripheral end portions 2-1a, 2-2a, 2-1b, and 2-2b of the wafer 10. By forming the groove 3 in this manner, it is possible to reduce the breakage of the wafer 10 when dicing the wafer 10.
- the shortest distance w) between the outer peripheral end portions is 5 mm or more in the 1200 V withstand voltage reverse blocking IGBT, and preferably 7 mm or more in the 1700 V reverse withstand blocking IGBT. If the shortest distance w11 between the groove and the outer peripheral edge of the wafer is too large, the number of chips cut out from one wafer 10 decreases and the cost increases. Therefore, according to the configuration and withstand voltage class of reverse blocking IGBT It is preferable to appropriately change the shortest distance w11 between the groove and the outer peripheral end of the wafer.
- the thickness of the wafer 10 after thinning is, for example, about 190 ⁇ m in the reverse blocking IGBT of 1200 V withstand voltage class, and may be, for example, about 270 ⁇ m in the reverse blocking IGBT of 1700 V withstand voltage class.
- the depth t of the groove 3 may be 85 ⁇ m or less in the reverse blocking IGBT of 1200 V withstand voltage class, and may be 175 ⁇ m or less in the reverse blocking IGBT of 1700 V withstand voltage class.
- the method of forming the groove 3 will be described later.
- the cross-sectional shape of the wafer 10 in which the groove 3 is formed will be described later.
- the p-type collector layer of the reverse blocking IGBT (the second semiconductor) Region: not shown) is formed. Then, in the surface layer of the side wall portion of the groove 3, a p-type collector layer and a p-type layer (third semiconductor region) in contact with the p-type isolation region are formed. That is, a p-type collector layer and a p-type channel stopper are formed by a p-type isolation region formed at a predetermined depth from the first main surface side of wafer 10 and a p-type layer formed on the sidewall of groove 3 Is connected. The p-type layer is formed simultaneously with, for example, the p-type collector layer.
- a collector electrode (second electrode) in contact with the p-type collector layer and the p-type layer is formed on the second main surface side of the wafer 10.
- the collector electrode is formed, for example, by physical vapor deposition such as chemical vapor deposition or sputtering.
- the grooves 3 are formed in a lattice shape on the second main surface of the wafer 10 so as not to reach the outer peripheral end 2 of the wafer 10.
- the wafer 10 is diced along the dicing line and cut into chips by using a dicing blade having a width smaller than the width in the short direction of the bottom surface of the groove 3.
- the reverse blocking IGBT formed in each element formation region 1 of the wafer 10 is cut into individual chips, and the reverse blocking IGBT is completed.
- the first main surface of wafer 10 on which the front surface element structure (including the front surface element structure of the breakdown voltage structure portion and the p-type isolation region of the isolation structure portion) of the reverse blocking IGBT is formed is protected Protected by Then, a tape is attached to the surface of the protective resist.
- the front surface element structure of the reverse blocking IGBT, the front surface element structure of the breakdown voltage structure portion, and the p-type isolation region of the isolation structure portion may be formed, for example, in the same manner as in the related art.
- the wafer 10 is fixed to, for example, a stage with the first main surface side to which the tape of the wafer 10 is attached facing down.
- the wafer 10 is uniformly removed from the second major surface side of the wafer 10 by, for example, grinding or etching, and the wafer 10 is thinned.
- the protective resist is formed on the first main surface of wafer 10
- the protective resist is formed across the first main surface to the side surface and the second main surface of wafer 10, but the protection formed on the back surface of wafer 10
- the resist is removed by thinning the wafer 10 from the second main surface side of the wafer 10.
- the tape is peeled off from the first main surface of the wafer 10.
- a resist mask having an opening for forming the groove 3 is formed on the second main surface of the wafer 10 by photolithography.
- the opening of the resist mask is a region of the resist applied to the second main surface of wafer 10 from the outer peripheral edge 2 of wafer 10 to the inner side of wafer 10 by at least the shortest distance w11 between the groove and the outer peripheral edge of wafer. It is not formed in the part corresponding to.
- the entire wafer 10 is immersed in an alkaline solution to perform wet etching, and the wafer 10 exposed at the opening of the resist mask is removed. Thereby, the groove 3 is formed on the second main surface of the wafer 10.
- the groove 3 is formed to have a depth t reaching the p isolation region formed on the first main surface of the wafer 10.
- the resist mask for forming the groove 3 may be formed by exposing and developing the pattern of the groove 3 on the resist. Specifically, for example, a resist applied to the second main surface of the wafer 10 is exposed using a stepper. At this time, a portion of the resist applied to the second main surface of wafer 10 corresponds to a region from the outer peripheral edge 2 of wafer 10 to the inner side of wafer 10 by at least the shortest distance w11 between the groove and the outer peripheral edge of wafer. The exposure conditions are set so that the pattern of the groove 3 is not exposed.
- channel 3 was formed is demonstrated.
- the grooves 3 are arranged in a lattice-like planar layout so as not to reach the outer peripheral end 2 of the wafer 10. For this reason, as shown in the cross section of the wafer 10 taken along the central and lower cutting lines AA 'and BB' in FIG.
- the thickness of 1b and 2-2b is thicker than that of the central portion 2-3a and 2-3b of the wafer 10 in which the groove 3 is formed.
- the side walls of the groove 3 are illustrated perpendicularly to the first main surface of the wafer 10, but As shown in FIG. 2, it has an inclination with respect to the first main surface of the wafer 10.
- grooves 3 are formed on the second main surface of wafer 10 at regular intervals, and the outer peripheral edge of the second main surface of wafer 10 It is not formed in the parts 2-1a and 2-2a. For this reason, in the cross-sectional shape of the wafer 10 along the cutting line A-A ', the unevenness due to the groove 3 is formed on the second main surface side.
- the element structure (not shown) of the reverse blocking IGBT and the breakdown voltage structure portion is formed in a portion of the wafer 10 sandwiched by the adjacent grooves 3.
- the groove 3 is formed leaving the thickness of the wafer 10 at the outer peripheral end portions 2-1b and 2-2b of the wafer 10.
- the groove 3 is not formed from the outer peripheral end 2-1b of the second main surface of the wafer 10 to the other outer peripheral end 2-2b, and does not penetrate the wafer 10 in the lateral direction. Therefore, the cross-sectional shape of the wafer 10 along the cutting line BB 'is such that the thickness of the central portion 2-3b is uniformly thin and removed, and the outer peripheral end portions 2-1b and 2-2b remain in a thick concave shape. .
- the groove 3 has a trapezoidal cross-sectional shape in which the first width w21 in the width direction of the opening of the groove 3 is wider than the second width w22 in the width direction of the bottom surface of the groove 3.
- the groove 3 is formed on the side wall of the groove 3 so that the (110) plane is exposed. The reason is that since the side walls of the groove 3 can be made flat, the diffusion depth of the p-type layer formed on the side wall of the groove 3 can be made uniform.
- the groove 3 having such a trapezoidal cross-sectional shape is formed, for example, by wet etching.
- the groove 3 is formed with the depth t reaching the p-type isolation region 4 by anisotropic etching using the resist mask 11 as a mask.
- anisotropic etching By the anisotropic etching, the angle ⁇ between the extension of the bottom of the groove 3 and the side wall of the groove 3 becomes an acute angle, and the groove 3 having a trapezoidal cross-sectional shape is formed.
- the first width w21 may be, for example, about 250 ⁇ m.
- the second width w22 may be, for example, about 100 ⁇ m.
- the cross-sectional shape of the groove 3 may be substantially rectangular (not shown).
- the groove 3 having a substantially rectangular cross-sectional shape is formed, for example, by dry etching. Specifically, the groove 3 is formed with a depth reaching the p-type isolation region by anisotropic etching using the resist mask as a mask. By forming the groove 3 by anisotropic etching, the angle ⁇ between the extension of the bottom of the groove 3 and the side wall of the groove 3 becomes about 90 °, and the groove 3 having a substantially rectangular cross-sectional shape is formed Ru.
- the end portion in the longitudinal direction of the groove 3 is formed so that the outer edge of the wafer 10 does not reach. Therefore, it is possible to reduce the occurrence of cracks in the wafer 10 during wafer processing, wafer transfer, and wafer handling. Therefore, the non-defective rate of wafer 10 can be improved as compared to a reverse blocking IGBT having a deep diffusion layer extending from the first main surface side of wafer 10 to the second main surface.
- a reverse blocking type in which a p-type isolation region formed on the first main surface of wafer 10 and a p-type collector layer are electrically connected by a p-type layer. It can apply to the manufacturing method of IGBT. Therefore, the reverse of providing a deep diffusion layer reaching from the first main surface side of wafer 10 to the second main surface without performing heat treatment at a temperature of 1300 ° C. for 100 hours or more for forming a p-type separation region A reverse blocking IGBT having a reverse withstand voltage similar to that of the blocking IGBT can be manufactured with a good yield rate.
- FIG. 3 is a cross-sectional view showing the cross-sectional shape of the groove according to the second embodiment.
- the semiconductor device manufacturing method according to the second embodiment is different from that of the first embodiment in that the bottom corner 31a is formed as a groove formed in the separation structure portion of the element formation region 1 of the wafer 10, as shown in FIG. To form a groove 31 having an arc shape.
- Such a groove 31 is formed, for example, by deforming the bottom corner portion of the groove formed in the isolation structure portion of the element formation region 1 of the wafer 10 into a circular shape.
- the first embodiment for example, wet etching is performed using the resist mask 11 as a mask, and the p-type formed in the isolation structure portion of the element formation region 1 on the second main surface of the wafer 10 A groove is formed to reach the separation area 4. Then, for example, a laser is irradiated to the bottom corner portion of the groove to deform it into a circular shape. As a result, a groove 31 having a circular arc shape on the bottom surface corner 31a is formed. Not only the bottom surface corner portion 31 a of the groove 31 but also the bottom surface of the groove 31 may be arc-shaped to form, for example, the groove 31 having a U-shaped cross-sectional shape.
- the etching may be performed twice and the bottom corner portion of the groove may be deformed into a circular shape by the second etching.
- first, wet etching is performed as in the first embodiment (first etching), and a groove reaching the p-type isolation region 4 is formed on the second main surface of the wafer 10.
- second etching isotropic etching such as dry etching is performed (second etching) to deform the bottom corner portion of the groove into a circular shape.
- the dimension of the groove 31 is, for example, the same as the dimension of the groove according to the first embodiment.
- the configuration of the reverse blocking IGBT other than the groove 31 formed in the wafer 10 is the same as the configuration of the reverse blocking IGBT formed in the wafer of the first embodiment.
- the manufacturing method of the reverse blocking IGBT except the method of forming the groove 31 according to the second embodiment is the same as the manufacturing method of the reverse blocking IGBT according to the first embodiment.
- the same effect as the method of manufacturing a semiconductor device according to the first embodiment can be obtained. Further, by making the shape of the bottom surface corner portion 31a of the groove 31 of the wafer 10 circular, stress applied to the bottom surface corner portion 31a of the groove 31 of the wafer 10 at the time of wafer handling and wafer handling during wafer processing of the wafer 10. Can be further reduced. Therefore, cracking of the wafer 10 can be further reduced.
- FIG. 4 is a cross-sectional view showing the cross-sectional shape of the groove according to the third embodiment.
- the semiconductor device manufacturing method according to the third embodiment is different from that of the first embodiment in the portion corresponding to the bottom of the groove formed in the isolation structure portion of the element formation region 1 of the wafer 10, as shown in FIG.
- the groove 32 is formed so that the thickness of the wafer 10 is partially thickened.
- Such grooves 32 are formed, for example, between two adjacent grooves, such that two grooves are arranged between the adjacent element formation regions 1 in the short direction of the formation region of the grooves 32. It is formed by reducing the protrusion to a predetermined height.
- the groove 32 is formed, for example, as follows.
- FIG. 5 is a cross-sectional view showing the state of the groove in the process of manufacturing the semiconductor device according to the third embodiment.
- FIG. 6 is a plan view showing the state of the wafer in the process of manufacturing the semiconductor device according to the third embodiment.
- the first resist mask 11 in which the formation region of the groove 32 is opened is formed on the first main surface of the wafer 10, and provided in the central portion in the formation region of the groove 32.
- a second resist mask 12 is formed which covers only the upper side of the dicing lines (not shown).
- the etching speed at which the portion under the second resist mask 12 of the wafer 10 is removed by the second resist mask 12 covering the central portion of the formation region of the groove 32 is the opening of the first and second resist masks 11 and 12 It is slower than the etching rate for removing the wafer 10 exposed to the portion.
- the grooves 32 separated into two grooves are formed by the projections 32 a that project from the bottom of the grooves 32 corresponding to the second resist mask 12.
- the height of the protrusion 32 a protruding from the bottom of the groove 32 is lowered, and a gap is generated between the upper end of the protrusion 32 a and the second resist mask 12.
- two grooves are connected in the space above the protrusion 32a, so that the groove 32 having a cross-sectional shape in which the bottom surface partially protrudes is formed by the protrusion 32a.
- the first width w31 in the short direction of the opening of the groove 32 may be, for example, 155 ⁇ m.
- the second width w32 in the short direction of the bottom surface of the groove 32 may be, for example, 100 ⁇ m.
- the third width w33 in the short direction of the protrusion 32a remaining on the bottom of the groove 32 after the end of etching is preferably such a width as to be removed by the dicing blade when dicing the wafer 10. The reason is that the bottom surface of the groove 32 formed at the end of the element of the completed reverse blocking IGBT cut into chips by dicing can be made flat.
- the third width w33 in the short direction of the protrusion 32a remaining on the bottom of the groove 32 after the end of etching may be, for example, 20 ⁇ m to 30 ⁇ m.
- the first and second resist masks 11 and 12 for forming the groove 32 may be connected to each other at an arbitrary position such as an end portion in the longitudinal direction of the groove 32 as shown in FIG.
- the connection of the first and second resist masks 11 and 12 can prevent the second resist mask 12 from drifting in the etching bath when the wafer 10 is etched. Therefore, the second resist mask 12 floating in the etching bath can be prevented from reattaching to the wafer 10 as a deposit. In addition, the deterioration of the etching bath due to the second resist mask 12 floating in the etching bath can be prevented.
- the configuration of the reverse blocking IGBT other than the groove 32 formed in the wafer 10 is the same as the configuration of the reverse blocking IGBT formed in the wafer of the first embodiment.
- the manufacturing method of the reverse blocking IGBT except the method of forming the groove 32 according to the third embodiment is the same as the manufacturing method of the reverse blocking IGBT according to the first embodiment.
- the same effect as the method of manufacturing a semiconductor device according to the first embodiment can be obtained.
- the thickness of the wafer 10 in a portion corresponding to the bottom surface of the groove 32 which is likely to be cracked can be formed thicker than in the prior art. This can further reduce the breakage of the wafer 10 during wafer processing, wafer transfer, and wafer handling.
- FIG. 7 is a plan view showing a planar shape of a groove according to the fourth embodiment.
- the semiconductor device manufacturing method according to the fourth embodiment is different from that of the first embodiment in the corner portion 1a of the element formation region 1 closest to the outer peripheral end 2 of the wafer 10, as shown in FIG.
- the fourth width w12 of the opening of the groove 33 up to the side wall corner 33a of the groove 33 facing 1a is narrower than the first width w21 of the opening of the other part of the groove 33.
- the sidewall corner 33a of the groove 33 closest to the outer peripheral end 2 of the wafer 10 is formed into an arc-like plane shape.
- FIG. 8 is a plan view showing another example of the planar shape of the groove according to the fourth embodiment.
- the fourth width w12 of the groove 33 is made narrower than the first width w21 by making the side wall corner portion 34 a of the groove 34 closest to the outer peripheral end 2 of the wafer 10 chamfered. May be
- Such grooves 33 and 34 appropriately set the pattern of a portion corresponding to the fourth width w12 of the groove 33 of the resist mask for forming the grooves 33 and 34, for example, and wet etching is performed using the resist mask as a mask. It is formed by doing.
- the side wall corners of the grooves 33 and 34 are formed so that the side wall corner portions 33a and 34a of the grooves 33 and 34 do not remain at the element end of the reverse blocking IGBT after dicing of the wafer 10. It is preferable to appropriately set the planar shape of the portions 33a and 34a.
- the dimensions of the grooves 33 and 34 other than the side wall corner portions 33a and 34a are, for example, the same as the dimensions of the grooves according to the first embodiment.
- the configuration of the reverse blocking IGBT other than the grooves 33 and 34 formed on the wafer 10 is the same as the configuration of the reverse blocking IGBT formed on the wafer of the first embodiment.
- the manufacturing method of the reverse blocking IGBT except the method of forming the grooves 33 and 34 according to the fourth embodiment is the same as the manufacturing method of the reverse blocking IGBT according to the first embodiment.
- the same effect as the method of manufacturing a semiconductor device according to the first embodiment can be obtained. Further, as described above, by setting the fourth width w12, the shortest distances w41 and w51 between the groove and the outer peripheral edge of the wafer can be increased. Therefore, the number of element formation regions 1 arranged on one wafer 10 can be increased. Therefore, the number of chips cut out from one wafer 10 can be increased.
- FIG. 9 is a characteristic diagram showing the crack occurrence rate of the wafer.
- the reverse blocking IGBT is manufactured on the wafer 10 by variously changing the shortest distance w11 between the groove and the outer peripheral edge of the wafer. The incidence of cracking was measured for each of the wafers 10 having different shortest distances w11 between the groove and the outer peripheral edge of the wafer.
- the withstand voltage class of the reverse blocking IGBT is 1700V.
- the thickness (including the emitter electrode) on the active region side of the reverse blocking IGBT is 190 ⁇ m.
- the thickness (not including the emitter electrode) on the active region side of the reverse blocking IGBT is 180 ⁇ m.
- the thickness on the side of the separation structure of the reverse blocking IGBT is 100 ⁇ m.
- the shortest distance w11 between the groove and the outer peripheral edge of the wafer was variously changed in the range of 9 mm or less.
- the crack occurrence rate of the wafer 10 is reduced by setting the shortest distance w11 between the groove and the outer peripheral edge of the wafer to 7 mm or more. Also, although not shown, the wafer in which the reverse blocking IGBT having a withstand voltage class of less than 1700 V is formed has a lower crack occurrence rate than the wafer 10 in which the reverse blocking IGBT having a withstand voltage class 1700 V is formed. It has been confirmed.
- the setting condition of the shortest distance w11 between the groove and the outer peripheral edge of the wafer for reducing the crack occurrence rate of the wafer 10 in which the reverse blocking IGBT of withstand voltage class 1700V is formed is reverse reverse IGBT of less than withstand voltage class 1700V. Even when applied to the formed wafer, the setting condition is to reduce the incidence of cracking of the wafer. Therefore, it was verified that by setting the shortest distance w11 between the groove and the outer peripheral edge of the wafer to 7 mm or more, the crack occurrence rate of the wafer in which the reverse blocking IGBT less than the withstand voltage class 1700 V is formed can be reduced.
- FIG. 10 is a cross-sectional view schematically showing an end shape of a wafer outer peripheral end according to the embodiment.
- the p-type collector region and the p-type are formed on the second main surface side of wafer 10 from the process of forming the front surface element structure and the like of the reverse blocking IGBT on the first main surface side of wafer 10. The process was carried out to form a layer. Then, after removing the protection resist for protecting the front surface element structure of the first main surface of wafer 10 and the resist mask for forming a groove in the second main surface of wafer 10, the outer peripheral edge of wafer 10 The end shape of the part 2 was observed.
- the wafer 10 is processed until the p-type collector region and the p-type layer are formed on the wafer 10, and the reverse blocking IGBT of withstand voltage class 1200 V is formed (hereinafter referred to as the first wafer)
- a wafer 10 (hereinafter, referred to as a second wafer) on which a reverse blocking IGBT of withstand voltage class 1700 V is formed was prepared.
- the thickness of the first wafer after thinning was 190 ⁇ m.
- the thickness of the second wafer after thinning was 270 ⁇ m.
- the shape of the end of the outer peripheral end 2 of such first and second wafers was observed.
- FIGS. 10 (a) and 10 (b) show end shapes of the outer peripheral end 2 of the first and second wafers, respectively.
- element structures and grooves are formed in the first and second wafers.
- FIGS. 10A and 10B it is confirmed that the end shape of the outer peripheral end 2 of the first wafer has an acute angle compared to the end shape of the outer peripheral end 2 of the second wafer. It was done. Thus, the thickness of the first wafer is thinner than the second wafer.
- the end shape of the outer peripheral end 2 of the first wafer has an acute angle as compared with the end shape of the second wafer.
- the first wafer deforms more easily than the second wafer, and the partition in the wafer carrier The friction due to contact with the part is less than in the case of the second wafer. As a result, it is estimated that the first wafer has a lower crack occurrence rate than the second wafer.
- the thickness of a wafer on which a reverse blocking IGBT with a withstand voltage class less than 1700 V, such as the first wafer, is formed is the second wafer on which a reverse stop IGBT with a withstand voltage class 1700 V is formed according to the withstand voltage class. Also becomes thinner. Therefore, a reverse blocking IGBT of withstand voltage class 1700 V is formed at the outer peripheral end 2 of the wafer on which the reverse blocking IGBT of less than the withstand voltage class 1700 V, such as the first wafer, is formed.
- the shape of the end portion is more acute than that of the outer peripheral end portion 2 of the second wafer.
- the wafer in which the reverse blocking IGBT having a withstand voltage class less than 1700 V is formed has a lower crack occurrence rate than the second wafer in which the reverse blocking IGBT having a withstand voltage class 1700 V is formed.
- the reverse blocking IGBT is described above as an example in the present invention, the present invention is not limited to the embodiment described above, and can be applied to a semiconductor device having a groove at an end portion of the element.
- the method for manufacturing a semiconductor device according to the present invention is used in industrial fields such as general-purpose inverters, AC servos, uninterruptible power supplies, switching power supplies, etc., and in consumer electronics fields such as microwave ovens, rice cookers or strobes. It is useful for manufacturing power semiconductor devices.
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Abstract
Description
図1は、実施の形態1による半導体装置の製造途中のウエハの状態を示す説明図である。図1の上側に、半導体装置が形成された状態のウエハ10の平面図を示す。図1において、切断線A-A’で切断したウエハ10の断面は、溝3をその短手方向に複数の素子形成領域1を横切るように切断した断面構造である(図1中央の断面図)。切断線B-B’で切断したウエハ10の断面は、溝3をその長手方向に切断した断面構造である(図1下側の断面図)。また、図2は、実施の形態1にかかる溝の断面形状について示す断面図である。
図3は、実施の形態2にかかる溝の断面形状について示す断面図である。実施の形態2にかかる半導体装置の製造方法が実施の形態1と異なるのは、図3に示すように、ウエハ10の素子形成領域1の分離構造部に形成される溝として、底面コーナー部31aの形状を円弧状とした溝31を形成することである。このような溝31は、例えば、ウエハ10の素子形成領域1の分離構造部に形成した溝の底面コーナー部を円形状に変形させることにより形成される。
図4は、実施の形態3にかかる溝の断面形状について示す断面図である。実施の形態3にかかる半導体装置の製造方法が実施の形態1と異なるのは、図4に示すように、ウエハ10の素子形成領域1の分離構造部に形成される溝の底面に対応する部分のウエハ10の厚みが部分的に厚くなるように当該溝32を形成することである。このような溝32は、例えば、隣り合う素子形成領域1の間に溝32の形成領域の短手方向に並ぶように2本の溝を形成し、この2本の溝の間に形成された突起部を所定の高さまで小さくすることにより形成される。
図7は、実施の形態4にかかる溝の平面形状について示す平面図である。実施の形態4にかかる半導体装置の製造方法が実施の形態1と異なるのは、図7に示すように、ウエハ10の外周端部2に最も近い素子形成領域1のコーナー部1aから当該コーナー部1aに対向する溝33の側壁コーナー部33aまでの溝33の開口部の第4幅w12を、溝33の他の部分の開口部の第1幅w21よりも狭くすることである。具体的には、例えば、ウエハ10の外周端部2に最も近い溝33の側壁コーナー部33aを円弧状の平面形状にする。
つぎに、ウエハ10の割れ発生率について検証する。図9は、ウエハの割れ発生率について示す特性図である。実施の形態1にしたがい、溝・ウエハ外周端部間の最短距離w11を種々変更してウエハ10に逆阻止型IGBTを作製した。溝・ウエハ外周端部間の最短距離w11の異なる各ウエハ10について、それぞれ割れ発生率を測定した。逆阻止型IGBTの耐圧クラスを1700Vとした。逆阻止型IGBTの活性領域側の厚さ(エミッタ電極を含む)を190μmとした。逆阻止型IGBTの活性領域側の厚さ(エミッタ電極を含まない)を180μmとした。逆阻止型IGBTの分離構造部側の厚さを100μmとした。溝・ウエハ外周端部間の最短距離w11を9mm以下の範囲で種々変更した。
つぎに、耐圧クラスが低いほどウエハ10の割れ発生率が低くなることについて検証した。図10は、実施例にかかるウエハ外周端部の端部形状について模式的に示す断面図である。実施の形態1にしたがい、ウエハ10の第1主面側に逆阻止型IGBTのおもて面素子構造などを形成する処理から、ウエハ10の第2主面側にp型コレクタ領域およびp型層を形成するまでの処理を行った。そして、ウエハ10の第1主面のおもて面素子構造を保護する保護レジスト、およびウエハ10の第2主面に溝を形成するためのレジストマスクを除去した後の、ウエハ10の外周端部2の端部形状を観察した。
2,2-1a,2-2a,2-1b,2-2b ウエハの外周端部
2-3a 素子形成領域を横切るウエハ断面の中央部
2-3b 溝を横切るウエハ断面の中央部
3 溝
10 ウエハ
Claims (5)
- 第1導電型の半導体ウエハの第1主面に、半導体素子のゲート電極からなるMOSゲート構造および第1電極と、前記半導体素子の耐圧を保持するための耐圧構造部と、前記半導体素子および前記耐圧構造部を囲む第2導電型の第1半導体領域と、を形成する工程と、
前記半導体ウエハの第2主面から前記第1半導体領域に達する溝を形成する工程と、
前記半導体ウエハの第2主面に第2導電型の第2半導体領域を形成するとともに、前記溝の側壁に前記第1半導体領域および前記第2半導体領域に電気的に接する第2導電型の第3半導体領域を形成する工程と、
前記第2半導体領域に電気的に接する第2電極を形成する工程と、
を含み、
前記溝を形成する工程では、前記半導体ウエハの外周端部から内側に所定の幅で当該半導体ウエハを残し、当該半導体ウエハの外周端部よりも当該半導体ウエハの内側に前記溝を形成することを特徴とする半導体装置の製造方法。 - 前記溝を形成する工程では、前記溝の側壁から前記半導体ウエハの外周端部までの距離を7mm以上残すように前記溝を形成することを特徴とする請求項1に記載の半導体装置の製造方法。
- 前記溝の断面形状は、台形状または円形状であることを特徴とする請求項1に記載の半導体装置の製造方法。
- 前記溝を形成する工程では、前記溝の底部に対応する部分の前記半導体ウエハの厚さが部分的に厚くなるように前記溝を形成することを特徴とする請求項1に記載の半導体装置の製造方法。
- 前記溝を形成する工程では、前記半導体素子および前記耐圧構造部を囲むように前記溝を形成することを特徴とする請求項1~4のいずれか一つに記載の半導体装置の製造方法。
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JP2013524532A JP5768885B2 (ja) | 2011-07-15 | 2011-07-15 | 半導体装置の製造方法 |
CN201180072259.1A CN103688346B (zh) | 2011-07-15 | 2011-07-15 | 用于制造半导体器件的方法 |
US14/233,147 US9240456B2 (en) | 2011-07-15 | 2011-07-15 | Method for manufacturing semiconductor device |
DE112011105448.3T DE112011105448T5 (de) | 2011-07-15 | 2011-07-15 | Verfahren zum Herstellen einer Halbleitervorrichtung |
PCT/JP2011/066262 WO2013011548A1 (ja) | 2011-07-15 | 2011-07-15 | 半導体装置の製造方法 |
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WO2014208201A1 (ja) * | 2013-06-27 | 2014-12-31 | 三菱電機株式会社 | 半導体装置およびその製造方法 |
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CN105814694B (zh) | 2014-10-03 | 2019-03-08 | 富士电机株式会社 | 半导体装置以及半导体装置的制造方法 |
CN117558622A (zh) * | 2024-01-11 | 2024-02-13 | 粤芯半导体技术股份有限公司 | 一种沟槽刻蚀方法及沟槽型栅器件 |
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- 2011-07-15 WO PCT/JP2011/066262 patent/WO2013011548A1/ja active Application Filing
- 2011-07-15 CN CN201180072259.1A patent/CN103688346B/zh not_active Expired - Fee Related
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CN103688346B (zh) | 2016-12-28 |
JP5768885B2 (ja) | 2015-08-26 |
DE112011105448T5 (de) | 2014-04-03 |
US9240456B2 (en) | 2016-01-19 |
US20140162413A1 (en) | 2014-06-12 |
JPWO2013011548A1 (ja) | 2015-02-23 |
CN103688346A (zh) | 2014-03-26 |
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