JP2009206291A - Semiconductor substrate, semiconductor device, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a processing cycle time without lowering quality of division when a semiconductor substrate having a plurality of semiconductor elements formed is divided by semiconductor element to form individual semiconductor devices. <P>SOLUTION: On the semiconductor substrate 1, the plurality of semiconductor elements 2 each having constructed functional elements are formed in a grid shape, and on longitudinal and lateral separating lines 4 individually separating the plurality of semiconductor elements 2, grooves 3 are formed which are continuous except at parts corresponding to corner parts of the semiconductor elements 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor substrate having a partially thinned diaphragm structure or beam structure, represented by MEMS (Micro Electro Mechanical System), a semiconductor device, and a method for manufacturing the same.

  A semiconductor pressure sensor or a MEMS acceleration sensor is a semiconductor device having a diaphragm structure or a beam structure that is partially thinned as typified by MEMS. In general, these sensors are manufactured by forming a plurality of sensors at the same time so as to have a diaphragm structure and a beam structure in a semiconductor wafer process, and then dividing them individually. The most commonly used method is to rotate a circular dicing saw with diamond or CBN particles fixed at high speed and crush it, and use cutting water to remove crushing waste and reduce frictional heat. It is done while flowing. However, since the diaphragm structure and the beam structure are fragile structures, they may be destroyed by cutting water pressure.

  In recent years, laser beam machining has attracted attention as a dividing method that does not require cutting water. For example, Patent Document 1 discloses a method in which a modified region by multiphoton absorption is formed in a semiconductor wafer by laser light, and division is performed by cleavage starting from the modified region. Multiphoton absorption is a phenomenon in which absorption occurs in a material when the intensity of light is very large even when the energy of the photon is smaller than the absorption bandgap of the material, that is, when it is optically transmitted. This will be described below with reference to the drawings.

  10A and 10B are a plan view and a cross-sectional view schematically showing the separation line of the semiconductor substrate and its periphery. In the figure, 101 is a semiconductor substrate, 102 is a semiconductor element (semiconductor device) formed on the semiconductor substrate 101, and 104 is a separation line that separates the semiconductor substrate 101 for each semiconductor element 102.

  With respect to the semiconductor substrate 101, the condensing point of the laser beam 108 is aligned inside the substrate in the region of the separation line 104 to cause multiphoton absorption in a predetermined thickness direction, and this multiphoton absorption occurs continuously or intermittently. The laser beam 108 is scanned along the center of the separation line 104 so as to form a modified region 109 along the separation line 104 inside the substrate, and a cut portion (crack) starting from the modified region 109 110 is generated. In this way, by applying an external force to both sides of the separation line 104 simultaneously, the semiconductor substrate 101 can be easily broken even with a relatively small external force. When the semiconductor substrate 101 is thin, it can be naturally broken by the cut portion (crack) 110 without applying an external force.

  There is also a method of reducing the thickness of the processed portion by forming grooves on the separation line in advance by anisotropic etching or the like. For example, in the method disclosed in Patent Document 2, anisotropic etching is performed after an etching protective film is formed on a semiconductor substrate having an azimuth plane (100) so that vertical and horizontal separation line portions are exposed. . In this case, etching stops on the azimuth plane (111) and a V-groove having an inclination angle of 54.7 degrees is formed. By applying an external force to the semiconductor substrate so as to expand the V-groove, the V-groove is formed. The semiconductor substrate can be divided along the line, that is, along the separation line.

Patent Document 3 discloses that a continuous linear first groove and a dashed second groove are formed as scrub grooves on a surface portion of a semiconductor substrate. In Patent Document 4, as a method for dividing a substrate on which a plurality of semiconductor devices having a diaphragm are formed, one of the vertical and horizontal kerfs for division is a continuous kerf and the other is not. It is disclosed that a continuous kerf portion is formed. Patent Document 5 discloses that two grooves are formed on the separation line corresponding to each of the four sides of each semiconductor device.
Japanese Patent No. 3408805 JP 2001-127008 A JP 2004-186340 A Japanese Utility Model Publication No. 4-109537 JP 2004-165227 A

  However, in the laser processing method disclosed in Patent Document 1, when the semiconductor substrate 101 is thick, it cannot be divided by the modified region 109 by a single scan. It is necessary to arrange the regions 109 almost in series in the thickness direction, which leads to an increase in tact time for processing.

  In the method disclosed in Patent Document 2, erosion of anisotropic etching is different from other portions at the portion where the vertical and horizontal V-grooves along the separation line intersect, and excessive etching is performed. Then, the etching does not stop at the azimuth plane (111), and the etching proceeds to the azimuth plane (211), for example. For example, if a V-groove is formed simultaneously with the step of forming a diaphragm structure that requires deeper etching than required for the V-groove, the intersection of the V-groove may be excessively etched and penetrate the semiconductor substrate. is there. In this case, the strength of the semiconductor substrate is extremely deteriorated, and the semiconductor substrate is damaged during handling.

  In the method disclosed in Patent Document 3 or Patent Document 4, only one of the grooves in the vertical direction and the horizontal direction is a continuous groove, and the four sides of the semiconductor device to be divided are not uniform. Stress is concentrated on the side where the groove is formed, and the semiconductor device is damaged from the side.

  In the method disclosed in Patent Document 5, two grooves for division are formed corresponding to each of the four sides of the semiconductor device, that is, a continuous groove is not formed on the separation line. For this reason, the straightness of separation deteriorates, and the shape of the semiconductor device after division, particularly the dimensions of each side, becomes nonuniform. As a result, for example, the pick-up property with a collet picked up at the side of the semiconductor device in a later process is deteriorated, and the productivity is lowered.

  In view of the above problems, the present invention improves processing tact without reducing the quality of division when a semiconductor substrate formed with a plurality of semiconductor elements is divided into semiconductor elements to form individual semiconductor devices. With the goal.

  In order to solve the above-described problems, a semiconductor substrate according to the present invention includes a plurality of semiconductor elements in which functional elements are constructed in a grid shape, and the plurality of semiconductor elements are separated from each other in the vertical and horizontal directions. A continuous groove except for a portion corresponding to a corner portion of each semiconductor element is formed on the separation line. This is convenient when a part of the structure is thinned, for example, a diaphragm structure having a recess on the back side of each semiconductor element.

  A method of manufacturing a semiconductor device according to the present invention is a method of manufacturing a semiconductor device by dividing a semiconductor substrate in which a plurality of semiconductor elements each having a functional element built therein are formed in a grid pattern, for each semiconductor element. Forming a continuous groove by anisotropic etching on the vertical and horizontal separation lines separating the individual semiconductor elements, except for the portions corresponding to the corners of each semiconductor element, and forming the grooves Forming a modified region in the substrate by irradiating a laser beam along each separated line and focusing on the inside of the substrate; and applying an external force to the semiconductor substrate in which the groove and the modified region are formed. And a step of dividing the semiconductor substrate along each separation line to form individual semiconductor devices.

In the step of forming the modified region, the number of times of laser light scanning for the groove forming portion can be made smaller than the number of times of laser light scanning for the non-groove forming portion.
When the step of forming the concave portion constituting the diaphragm structure is formed on the back side of each semiconductor element by anisotropic etching, the step of forming the groove can be performed simultaneously with the step of forming the concave portion.

  The semiconductor device of the present invention is manufactured as described above, and has a notch portion that is continuous except for a corner portion on each side of the back surface of the substrate opposite to the semiconductor element. In addition, the semiconductor device has a diaphragm structure including a recess on the back side of the semiconductor element.

  The semiconductor substrate of the present invention forms a continuous groove on the vertical and horizontal separation lines that individually separate a plurality of semiconductor elements, except for a portion corresponding to a corner portion of each semiconductor element, Since the substrate is thin at the groove and stress is easily concentrated when dividing by cleavage, etc., stable division with good straightness is possible compared to a semiconductor substrate without such a groove. Become.

  In the method of manufacturing a semiconductor device according to the present invention, a continuous groove is formed on each separation line of the semiconductor substrate except for a portion corresponding to a corner portion of each semiconductor element. That is, it is extremely difficult to control etching. Since the formation of the groove intersection is eliminated, the groove can be formed very easily and stably. Since the groove on each separation line is almost entirely continuous in a straight line, when the modified region that is the starting point for the division is formed by the laser beam, the number of times the laser beam is scanned for the groove forming portion is changed. Even if the number is less than the portion, it is possible to stably perform division with excellent straightness, and it is possible to shorten the machining tact time. When forming a recess that forms the diaphragm structure on the back side of each semiconductor element by anisotropic etching, it is sufficient to form a groove at the same time in the step of forming the recess. The process will not increase, and it will not increase costs or lead time.

  Since the semiconductor device of the present invention is manufactured as described above, each side of the back surface of the substrate opposite to the semiconductor element has a cutout portion that is continuous except for the corner portion. Can be prevented from climbing to the side of the apparatus. Since the corner portion has no notch, the area of the back surface of the apparatus is not reduced, and an adhesion area can be secured.

Embodiments of the present invention will be described below with reference to the drawings.
1 is a plan view of a semiconductor substrate according to an embodiment of the present invention, FIG. 2 is a partially enlarged view of the semiconductor substrate, FIGS. 3 and 4 are cross-sectional views taken along line AA ′ of FIG. It is -B 'sectional drawing.

  1 and 2, a semiconductor substrate 1 is made of Si single crystal, and a plurality of semiconductor elements 2 in which functional elements are constructed are formed in a grid pattern on one surface. The semiconductor element 2 shown in the drawing becomes a diaphragm pressure sensor (semiconductor device) after being divided. The semiconductor element 2 itself is made as thin as possible as a detection part, and a concave part 5 is formed on the back side, and these have a diaphragm structure. It is composed. An example of such a diaphragm pressure sensor is a microphone sensor. The diaphragm vibrates due to air oscillated by sound, and the displacement of the diaphragm changes the conductor capacitance between the passive diaphragm / vibrating diaphragm, thereby changing the vibration frequency and electric signal. Converted.

  The separation line 4 separating the plurality of semiconductor elements 2 is a divided region set for dividing each semiconductor element 2 and extends in the vertical direction and the horizontal direction so as to be orthogonal to each other. On each separation line 4 and on the back surface of the substrate opposite to the semiconductor element 2, a groove 3 that is linearly continuous is formed except for a portion corresponding to a corner portion of each semiconductor element 2.

A method for manufacturing the semiconductor substrate 1 and the semiconductor device will be described.
As shown in FIG. 5A, an etching mask 6 is formed on a semiconductor substrate 1 (see FIG. 1) in which a plurality of semiconductor elements 2 are separated by separation lines 4 and formed in a grid shape. The etching mask 6 is formed, for example, by depositing a silicon oxide film or the like by a CVD method and patterning by a lithography technique so as to have an opening in a region where the recess 5 and the groove 3 are formed. Although not shown, an etching mask is left on the entire surface on which the semiconductor element 2 is formed.

  Next, as shown in FIG. 5B, the recess 5 and the groove 3 are formed by anisotropic etching. For the anisotropic etching, for example, a KOH solution or a TMAH (tetramethylammonium hydroxide) solution is used. At this time, since the groove 3 is formed on the separation line 4 except the portion corresponding to the corner portion of each semiconductor element 2 as described above, no abnormal erosion occurs at the intersection of the separation lines 4 and the etching depth is reduced. Even if the recesses 5 are formed at the same time, the etching can be stopped at a desired depth. That is, the depth and width of the groove 3 can be determined by the opening width of the etching mask 6.

For example, when the semiconductor device is a microphone sensor, the Si single crystal substrate is Φ4 to 12 inches and the thickness is 100 to 1000 μm, the planar size of the target semiconductor device is about 1 to 200 mm ² , and the finished thickness is about 10 to 900 μm. If there is, the thickness of the planar diaphragm (semiconductor element 2 here) is about 1 to 5 μm on the passive side and about 1 to 5 μm on the vibration side. Therefore, the recess 5 is formed by etching so as to have such a thickness. The planar size of the recess 5 is about 0.5 to 150 mm ² . The groove 3 has a width of about 20 to 500 um (preferably narrow in order to improve the number of chips taken), and a depth of about 10 to 890 um (preferably deep to facilitate separation and division, but needlessly It is assumed that the substrate is not cracked).

  After the etching is completed, the etching mask 6 is removed as shown in FIG. In this case, for example, a BHF solution is used, but the etching mask 6 may be left if there is no particular problem.

  After that, as shown in FIGS. 5D and 5E, the semiconductor substrate 1 is mounted on the expanded tape 7, and the laser beam 8 is focused along each separation line 4 and inside the semiconductor substrate 1. Then, a modified region 9 is formed inside the semiconductor substrate 1. At this time, the laser beam 8 is scanned along the longitudinal direction of the groove 3 while moving the focal point in the substrate thickness direction so that the microcracks generated from the modified region 9 propagate into the groove 3.

  Finally, as shown in FIG. 5 (f), by applying an external force F to the semiconductor substrate 1 in which the groove 3 and the modified region 9 are formed, that is, by applying an external force F that expands the expanded tape 7, A crack 10 starting from the modified region 9 formed along the separation line 4 is generated to divide the semiconductor substrate 1 to obtain individual semiconductor devices 11. If the above-mentioned microcracks have advanced to the groove 3 prior to the external force F, the external force F can be reduced and processing with smaller energy becomes possible.

  When the semiconductor substrate 1 is thick, as shown in FIGS. 6A and 6B, the laser beam 8 is scanned a plurality of times so that the modified regions 9 are aligned in the substrate thickness direction, thereby dividing the substrate. Can be easily. The laser beam 8 can be divided even if the number of times of scanning with the laser beam 8 is less than the portion where the groove 3 is not formed compared to the portion where the groove 3 is not formed.

  FIG. 6A shows a portion where the groove 3 is formed, and the modified regions 9a and 9b are formed by setting the number of scans of the laser light 8 twice. FIG. 6B shows a non-formed portion of the groove 3, and the modified regions 9 a, 9 b, 9 c are formed with the number of scans of the laser light 8 being three.

According to the configuration of the semiconductor substrate 1 and the manufacturing method of the semiconductor device 11 described above, the following effects can be obtained.
Since the groove 3 that is linearly continuous is formed in a portion other than the portion corresponding to the corner portion 15, it is possible to stably and easily perform division with excellent straightness. Even when the modified region 9 serving as a starting point for the division is formed by the laser beam 8, the number of scans of the laser beam 8 in the portion where the groove 3 is formed is equal to the number of scans of the laser beam 8 in the portion where the groove 3 is not formed. And the machining tact time can be shortened.

  On the other hand, since the formation of the modified region 9 by the laser beam 8 facilitates the formation of cracks, the groove 3 does not have to have a V-groove shape, for example, which is extremely difficult to control the etching. Is possible. Since the groove 3 is not formed in the portion corresponding to the corner portion 15 (intersection portion of the separation line 4), the abnormal erosion at the time of etching as in the case where the groove is formed also in this portion does not occur.

  Since both the groove 3 and the modified region 9 are formed, even when a crack is formed by expanding or the like, there is a width range for the groove width, so compared to the case where the groove 3 is not formed, Division with excellent straightness can be easily performed.

If the groove 3 is formed simultaneously with the anisotropic etching step for forming the recess 5, there is no particular increase in the number of steps, and an increase in cost and an increase in lead time can be avoided.
FIG. 7 shows the semiconductor device 11 divided from the semiconductor substrate 1. A semiconductor element 2 and a recess 5 are formed in the semiconductor substrate 1 ′, and a notch (dent) 12 along each side is formed on each side excluding the corner portion on the back side of the substrate opposite to the semiconductor element 2. Have. The notch 12 is obtained by dividing the groove 3 in the longitudinal direction.

  In general, a semiconductor device has a quadrangular shape in plan view, and if it is an elongated quadrangular shape, it is likely to be broken from the long side, but it is rarely broken from the short side. The starting point at the time of bending is a crack formed in the edge portion. In this respect, since the semiconductor device 11 of the present embodiment has the notch portion 12 at the edge portion, in other words, the edge portion exists above and inside the original edge portion, the folding start point Cracks are less likely to occur. For this reason, in the semiconductor device 11, cracks and chipping at the edge portion are suppressed, the bending strength is dramatically improved, and the mechanical strength is excellent.

  8A and 8B show a state in which the semiconductor device 11 is mounted on the mounting substrate 13. The semiconductor device 11 and the mounting substrate 13 are bonded with a die bond material 14 as is generally done.

  At the time of bonding, in order to control the creeping of the die bond material 14 on the side surface of the semiconductor device 11, it is required to strictly control the coating amount of the die bond material 14. Since there is a notch 12 at the edge portion, the surface tension at the notch 12 suppresses the creeping of the die bond material 14 and can be managed much more easily than when there is no notch 12. It is.

  On the other hand, since the notch 12 is not present in the corner 15 of the semiconductor device 11, the substantial area of the back surface of the semiconductor device 11 is not reduced, but rather the die bond area is increased by the presence of the notch 12. In addition, the bond strength between the semiconductor device 11 and the mounting substrate 13 can be increased. Further, since the notch 12 is not provided in the corner 15 of the semiconductor device 11, the thickness of the semiconductor device 11 can be detected as usual, and the mounting height variation accuracy of the semiconductor device 11 can be controlled without change as usual.

  In the above embodiment, the diaphragm structure is formed in the semiconductor substrate 1 and the semiconductor device 11, but it is needless to say that the diaphragm structure is not necessary. The semiconductor substrate 1 may also be a compound semiconductor substrate in addition to a silicon substrate.

  For example, when an acceleration sensor is manufactured as the semiconductor device 11, as shown in FIGS. 9A and 9B, the recess 5 ′ is formed on the upper surface of the semiconductor substrate 1, and the semiconductor element 2 is installed in the opening. The groove 3 is formed on the lower surface of the semiconductor substrate 1. The effects of the subsequent steps and the grooves 3 are the same as described above.

  According to the present invention, when a semiconductor substrate on which a plurality of semiconductor elements are formed is divided into semiconductor devices corresponding to the respective semiconductor elements, the processing tact can be improved without increasing the processing cost and reducing the processing quality. In particular, it is useful for manufacturing a MEMS sensor or the like having a diaphragm structure.

The top view of the semiconductor substrate of one embodiment of the present invention The top view which expands and shows a part of the semiconductor substrate A-A 'sectional view of the semiconductor substrate in FIG. B-B 'sectional view of the semiconductor substrate in FIG. Sectional drawing which shows the manufacturing method of the semiconductor device of one Embodiment of this invention Sectional drawing which shows a part of manufacturing method of the same semiconductor device in detail Plan view and sectional view of the semiconductor device Sectional drawing which shows the state which mounted the semiconductor device in the semiconductor substrate Sectional drawing which shows the manufacturing method of the semiconductor device of other embodiment of this invention Plan view and sectional view showing a conventional semiconductor substrate and its dividing method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Semiconductor element 3 Groove 4 Separation line 5 Concave part 6 Etching mask 7 Expanding tape 8 Laser beam 9, 9a, 9b, 9c Modified area 10 Crack 11 Semiconductor device 12 Concave part 13 Mounting board 14 Die bond material 15 Corner part

Claims (7)

  A plurality of semiconductor elements in which functional elements are constructed are formed in a grid shape, and a portion corresponding to a corner portion of each semiconductor element is formed on a vertical and horizontal separation line separating the plurality of semiconductor elements individually. A semiconductor substrate, wherein a continuous groove is formed except for.   2. The semiconductor substrate according to claim 1, wherein the semiconductor substrate has a diaphragm structure provided with a recess on the back side of each semiconductor element.   A method of manufacturing a semiconductor device by dividing a semiconductor substrate on which a plurality of semiconductor elements each having a functional element are formed in a grid shape, and separating the plurality of semiconductor elements individually. Forming a continuous groove by anisotropic etching, excluding a portion corresponding to a corner portion of each semiconductor element, on a separation line in each direction and a lateral direction, and along each separation line in which the groove is formed and on a substrate A step of forming a modified region inside the substrate by irradiating a laser beam with a focus on the inside, and applying an external force to the semiconductor substrate on which the groove and the modified region are formed, and applying the semiconductor substrate to each separation line And a step of forming individual semiconductor devices by dividing the semiconductor device.   4. The method of manufacturing a semiconductor device according to claim 3, wherein, in the step of forming the modified region, the number of times of laser beam scanning with respect to the groove forming portion is smaller than the number of times of laser light scanning with respect to the non-groove forming portion.   A step of forming a recess constituting the diaphragm structure on the back side of each semiconductor element by anisotropic etching, wherein the step of forming a groove is performed simultaneously with the step of forming the recess. A method for manufacturing a semiconductor device according to claim 3.   4. A semiconductor device manufactured by the method according to claim 3, wherein each side of the back surface of the substrate opposite to the semiconductor element has a notch portion that is continuous except for a corner portion.   7. The semiconductor device according to claim 6, wherein the semiconductor device has a diaphragm structure provided with a recess on the back side of the semiconductor element.

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