JP2010165918A - Photodiode array and radiation detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photodiode array, capable of suppressing deterioration in mechanical strength of semiconductor substrates caused by forming modified regions, while suppressing crosstalks. <P>SOLUTION: The photodiode array 1a includes: the semiconductor substrate 3; and a plurality of p-type semiconductor regions 5 that are disposed side by side, on the rear side of the semiconductor substrate 3 and each compose a photodiode by a p-n junction with the semiconductor substrate 3. A modified region 50 is formed by focusing the focusing point at a prescribed position in a region 37, to have laser beams irradiated in the region 37 between the adjacent p-type semiconductor regions 5, while the modified region 50 extends, in a direction of crossing the arranging direction of the adjacent p-type semiconductor region 5, and the modified region is not formed in a region 38 surrounded by four adjacent p-type semiconductor regions 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photodiode array and a radiation detector.

  As a photodiode array, a photodiode array including a plurality of photodiodes formed on the light incident surface side of the semiconductor substrate and a modified region formed between adjacent photodiodes reaching the light incident surface of the semiconductor substrate. Known (see, for example, Patent Documents 1 and 2). In the photodiode arrays described in Patent Documents 1 and 2, a modified region is formed by irradiating a semiconductor substrate with laser light along a region between adjacent photodiodes. Thus, carriers generated by incident light from the light incident surface side and diffused to the adjacent photodiodes are trapped in the modified region, and crosstalk between adjacent photodiodes is suppressed.

  In addition, a plurality of pixel electrodes disposed on an insulating substrate, a light absorption layer that is disposed on the pixel electrode and generates carriers upon incidence of light, a barrier layer disposed on the light absorption layer, and an adjacent pixel A photodiode including a modified region (potential barrier region) formed in a barrier layer along a region between electrodes is known (see, for example, Patent Document 3). In the photodiode described in Patent Document 3, a modified region (potential barrier region) is formed by irradiating the barrier layer with laser light along between adjacent pixel electrodes. As a result, carriers diffusing to adjacent pixel electrodes are blocked by the modified region (potential barrier region), and crosstalk between adjacent pixel electrodes is suppressed.

JP 2005-19465 A Japanese Unexamined Patent Publication No. 63-128677 Japanese Patent Laid-Open No. 10-70303

  An object of the present invention is to provide a photodiode array and a radiation detector capable of suppressing a decrease in mechanical strength of a semiconductor substrate due to formation of a modified region while suppressing crosstalk.

  The photodiode array according to the present invention is arranged side by side on the first conductivity type semiconductor substrate and one surface side of the semiconductor substrate, and each of the plurality of second arrays constituting the photodiode by bonding to the semiconductor substrate. A conductive type semiconductor region, and a region between the adjacent second conductive type semiconductor regions is irradiated with a laser beam with a converging point aligned with a predetermined position of the adjacent second conductive type. The modified region is formed to extend in a direction intersecting the arrangement direction of the type semiconductor region, and the modified region is not formed in a region surrounded by at least three adjacent second conductivity type semiconductor regions. Features.

  In the photodiode array according to the present invention, the modified region is formed in the region between the adjacent second conductivity type semiconductor regions so as to extend in a direction intersecting the arrangement direction of the adjacent second conductivity type semiconductor regions. Yes. In this case, carriers generated by the incidence of light and diffusing into a region between the adjacent second conductivity type semiconductor regions are trapped in the modified region, and crosstalk can be suppressed.

  By the way, the mechanical strength of the portion of the semiconductor substrate where the modified region is formed is lower than that of the portion where the modified region is not formed. For this reason, when an external force is applied to the semiconductor substrate, the stress tends to concentrate on the modified region, and cracks may occur in the portion where the modified region is formed. Here, a modified region extending from a region between adjacent second conductivity type semiconductor regions and a modified region extending from a region between other adjacent second conductivity type semiconductor regions in a direction crossing the modified region. Are continuous in a region surrounded by at least three adjacent second-conductivity-type semiconductor regions, cracks generated in the modified region grow in different directions. If such crack growth is repeated, cracks grow over a wide area of the semiconductor substrate. For this reason, there is a limit to suppressing a decrease in the mechanical strength of the semiconductor substrate due to the formation of the modified region.

  However, in the photodiode array according to the present invention, the modified region is not formed in a region surrounded by at least three adjacent second conductivity type semiconductor regions. In this case, a decrease in mechanical strength of the semiconductor substrate is suppressed in a region surrounded by at least three adjacent second conductivity type semiconductor regions. Therefore, even when an external force is applied to the semiconductor substrate 3, it is possible to suppress the occurrence of cracking in a region surrounded by at least three adjacent second conductivity type semiconductor regions. Further, even when a crack occurs in the modified region, the growth of the crack in a region surrounded by at least three adjacent second conductivity type semiconductor regions is suppressed. Thereby, the crack of the modified region is prevented from growing over a wide area of the semiconductor substrate. Therefore, it is possible to suppress a decrease in mechanical strength of the semiconductor substrate due to the formation of the modified region.

  The plurality of second conductivity type semiconductor regions are two-dimensionally arranged in a matrix, and the modified region is adjacent to the region between the second conductivity type semiconductor regions adjacent in the row direction in the column direction. It is preferably formed only in the region between the second conductivity type semiconductor regions.

  The photodiode array according to the present invention is arranged side by side on the first conductivity type semiconductor substrate and one surface side of the semiconductor substrate, and each of the plurality of second arrays constituting the photodiode by bonding to the semiconductor substrate. A conductive type semiconductor region, and a region between the adjacent second conductive type semiconductor regions is irradiated with a laser beam with a converging point aligned with a predetermined position of the adjacent second conductive type. A first modified region is formed extending in a direction crossing the direction of arrangement of the semiconductor region of the type, and a region surrounded by at least three adjacent semiconductor regions of the second conductivity type is concentrated at a predetermined position of the region. The second modified region is formed by irradiating the laser beam with the light spot aligned, and the first modified region and the second modified region are located apart from each other. To do.

  In the photodiode array according to the present invention, the first modified region is formed in the region between the adjacent second conductivity type semiconductor regions, and the region surrounded by the at least three adjacent second conductivity type semiconductor regions is formed. The second modified region is formed. In this case, carriers generated by the incidence of light and diffusing into each of a region between adjacent second conductivity type semiconductor regions and a region surrounded by at least three adjacent second conductivity type semiconductor regions are the first. And it will be trapped in each of the 2nd modification field, and crosstalk can be controlled.

  In the photodiode array according to the present invention, the first modified region and the second modified region are formed apart from each other. In this case, a decrease in mechanical strength of the semiconductor substrate is suppressed in a region between the first modified region and the second modified region. Therefore, even if a crack occurs in the first or second modified region, it is suppressed that the crack grows in a region between the first modified region and the second modified region. . Thereby, the crack of the modified region is prevented from growing over a wide area of the semiconductor substrate. Therefore, it is possible to suppress a decrease in mechanical strength of the semiconductor substrate due to the formation of the modified region.

  The plurality of second conductivity type semiconductor regions are two-dimensionally arranged in a matrix, and the first modified region includes a region between the second conductivity type semiconductor regions adjacent in the row direction and a column direction. The second modified region is formed in a region between the second conductive type semiconductor regions adjacent to each other in a direction crossing the row direction and the column direction. Preferably it is formed.

  The photodiode array according to the present invention is arranged side by side on the first conductivity type semiconductor substrate and one surface side of the semiconductor substrate, and each of the plurality of second arrays constituting the photodiode by bonding to the semiconductor substrate. And the second conductivity type semiconductor regions are two-dimensionally arranged in a matrix, and among the plurality of second conductivity type semiconductor regions, four adjacent second conductivity type semiconductor regions are provided. First and second second conductivity type semiconductor regions adjacent to each other in the row direction, and a third second conductivity type semiconductor region adjacent to the first second conductivity type semiconductor region in the column direction. And a fourth second conductivity type semiconductor region adjacent to the first second conductivity type semiconductor region in a direction intersecting the row direction and the column direction, and the first and second second conductivity types. Type semiconductor region and third and fourth second conductivity type semiconductors A first modified region extending continuously in the row direction is formed in a region between the first and second regions by irradiating a laser beam with a condensing point at a predetermined position of the region. The region between the second second conductivity type semiconductor regions and the region between the third and fourth second conductivity type semiconductor regions are aligned with a condensing point at a predetermined position of each of the laser beams. , A second modified region extending in the column direction is formed, and the first modified region and the second modified region are located apart from each other.

  In the photodiode array according to the present invention, one of the first and second modified regions is formed between each of the first to fourth second conductivity type semiconductor regions. As a result, carriers generated by the incidence of light and diffusing between the first to fourth second conductivity type semiconductor regions are trapped in either the first or second modified region. Crosstalk can be suppressed.

  In the photodiode array according to the present invention, the first modified region and the second modified region are formed apart from each other. In this case, a decrease in mechanical strength of the semiconductor substrate is suppressed in a region between the first modified region and the second modified region. Therefore, even if a crack occurs in the first or second modified region, the growth of cracks is suppressed in the region between the first modified region and the second modified region. Become. Thereby, the crack of the modified region is prevented from growing over a wide area of the semiconductor substrate. Therefore, it is possible to suppress a decrease in mechanical strength of the semiconductor substrate due to the formation of the modified region.

  The semiconductor substrate also includes a first region in which a plurality of second conductivity type semiconductor regions are disposed, and a second region that surrounds the first region and whose outer edge forms the outer edge of the semiconductor substrate. The modified region is preferably not formed in the second region. In this case, since the modified region is not formed in the second region, the formation of a region with reduced mechanical strength in the second region is suppressed. Therefore, even when an external force is applied to the second area by dicing by a blade or the like, the occurrence of cracks in the second area is suppressed. Therefore, it is possible to further suppress the decrease in the mechanical strength of the semiconductor substrate due to the formation of the modified region.

  The semiconductor substrate also includes a first region in which a plurality of second conductivity type semiconductor regions are disposed, and a second region that surrounds the first region and whose outer edge forms the outer edge of the semiconductor substrate. In the second region, it is preferable that a modified region is formed by irradiating a laser beam with a focusing point at a predetermined position of the region. In this case, the carriers generated between the side surface of the semiconductor substrate and the modified region formed in the second region by the incidence of light and the carriers generated due to crystal defects on the side surface of the semiconductor substrate are the second It is trapped in the modified region formed in this region. Thereby, since it is suppressed that the said carrier reaches the 2nd conductivity type semiconductor area | region arrange | positioned in the 1st area | region, crosstalk can further be suppressed.

  In addition, a plurality of modified regions in the second region are formed to extend in a direction along the outer edge of the semiconductor substrate, and the modified regions preferably surround the first region. In this case, the carriers generated between the side surface of the semiconductor substrate and the modified region formed in the second region by the incidence of light and the carriers generated due to crystal defects on the side surface of the semiconductor substrate are the second Thus, the modified region formed in this region is surely trapped. Thereby, since it is further suppressed that the carrier reaches the second conductivity type semiconductor region arranged in the first region, crosstalk can be further suppressed.

  The modified region of the second region is an outer edge of the semiconductor substrate in a region between the plurality of first parts extending in the direction along the outer edge of the semiconductor substrate and arranged apart from each other and the adjacent first parts. A plurality of second portions extending in a direction intersecting with the first portion and spaced apart from the first portion, wherein the plurality of first and second portions surround the first region. preferable. In this case, carriers generated between the side surface of the semiconductor substrate and the modified region formed in the second region by the incidence of light and carriers generated due to crystal defects on the side surface of the semiconductor substrate are the first. And will be trapped by the second part. Thereby, since it is further suppressed that the carrier reaches the second conductivity type semiconductor region arranged in the first region, crosstalk can be further suppressed. Moreover, since the 2nd part is located away from the 1st part, the fall of mechanical strength is suppressed in the area | region between the 1st part and the 2nd part. Therefore, even if a crack occurs in any of the first and second portions, the growth of the crack is suppressed in the region between the first portion and the second portion. Therefore, it is possible to suppress the crack in the modified region from growing over a wide area of the semiconductor substrate while suppressing the crosstalk as described above.

  Moreover, it is preferable that the bump is disposed on a region surrounded by at least three adjacent second conductivity type semiconductor regions. In this case, the external force applied to the photodiode array via the bumps when mounting the photodiode array and the wiring board is applied to the region in which the growth of cracks is suppressed. As a result, even if an external force is applied to the photodiode array via the bumps, the growth of cracks in the semiconductor substrate can be suppressed.

  A radiation detector according to the present invention includes the photodiode array according to the present invention, and a scintillator disposed on one surface of the semiconductor substrate or on the other surface facing the one surface. . In this case, since the photodiode array according to the present invention is provided, it is possible to suppress a decrease in mechanical strength of the semiconductor substrate due to the formation of the modified region while suppressing crosstalk.

  ADVANTAGE OF THE INVENTION According to this invention, the photodiode array and radiation detector which can suppress the fall of the mechanical strength of a semiconductor substrate by forming a modification area | region can be provided, suppressing crosstalk.

FIG. 3 is a plan view showing a part of the photodiode array according to the first embodiment. It is a schematic diagram which shows the cross-sectional structure along the II-II line | wire in FIG. It is a schematic diagram which shows the cross-sectional structure for demonstrating the manufacturing method of the photodiode array which concerns on 1st Embodiment. It is a schematic diagram which shows the cross-sectional structure for demonstrating the manufacturing method of the photodiode array which concerns on 1st Embodiment. It is a top view which shows the photodiode array which concerns on 2nd Embodiment. It is a schematic diagram which shows the cross-sectional structure along the VI-VI line in FIG. It is a top view which shows the modification of the photodiode array which concerns on embodiment of this invention. It is a top view which shows the modification of the photodiode array which concerns on embodiment of this invention. It is a top view which shows the modification of the photodiode array which concerns on embodiment of this invention. It is a top view which shows the modification of the photodiode array which concerns on embodiment of this invention. It is a schematic diagram which shows the cross-sectional structure for demonstrating the modification of the manufacturing method of the photodiode array which concerns on embodiment of this invention. It is a schematic diagram which shows the cross-sectional structure of the radiation detector which concerns on this embodiment. It is a schematic diagram which shows the cross-sectional structure for demonstrating the manufacturing method of the radiation detector which concerns on this embodiment. It is a schematic diagram which shows the cross-sectional structure of the modification of the radiation detector which concerns on this embodiment. It is a schematic diagram which shows the cross-sectional structure for demonstrating the modification of the manufacturing method of the radiation detector which concerns on this embodiment. It is a schematic diagram which shows the cross-sectional structure for demonstrating the modification of the manufacturing method of the radiation detector which concerns on this embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

[Photodiode array]
[First Embodiment]
The configuration of the photodiode array 1a according to the first embodiment will be described with reference to FIGS. FIG. 1 is a plan view showing the photodiode array 1a according to the first embodiment. FIG. 2 is a schematic diagram showing a cross-sectional configuration along the line II-II in FIG.

  As shown in FIGS. 1 and 2, the back-illuminated photodiode array 1a includes an n-type (first conductivity type) semiconductor substrate 3, a p-type (second conductivity type) semiconductor region 5, and an n-type semiconductor. Region 7.

The semiconductor substrate 3 has a front surface (other surface) 3a and a back surface (one surface) 3b that face each other. The front surface 3a is an incident surface for the light L1, and the rear surface 3b is a signal output surface. The semiconductor substrate 3 includes a region (first region) 35 in which a plurality of p-type semiconductor regions 5 to be described later are disposed, and a region (second region) that surrounds the region 35 and whose outer edge forms the outer edge of the semiconductor substrate 3. 36. The semiconductor substrate 3 is a square substrate made of, for example, silicon (Si) and having a thickness of, for example, 150 μm. The semiconductor substrate 3 contains impurities (for example, phosphorus), and its concentration is, for example, 5 × 10 ¹² / cm ³ . The semiconductor substrate 3 has a modified region 50 to be described later.

The p-type semiconductor regions 5 are two-dimensionally arranged in a matrix (for example, 4 × 4) spaced apart from each other on the back surface 3 b side of the semiconductor substrate 3. The plurality of p-type semiconductor regions 5 include a p-type semiconductor region 5 arranged in the row direction (first direction) and a p-type semiconductor region 5 arranged in the column direction (second direction) intersecting the row direction. Yes. Each p-type semiconductor region 5 is formed in a square shape by, for example, Si, and the thickness thereof is, for example, 0.55 μm. Each p-type semiconductor region 5 contains an impurity (for example, boron), and its concentration is, for example, 1 × 10 ¹⁹ / cm ³ . Each p-type semiconductor region 5 is a pixel portion including a photodiode 13 constituted by a pn junction 11 with the semiconductor substrate 3. The pn junction 11 functions as a light sensitive region of the photodiode 13 due to a depletion layer spreading on the semiconductor substrate 3.

The n-type semiconductor region 7 is disposed so as to surround each p-type semiconductor region 5 in a region between the adjacent p-type semiconductor regions 5 on the back surface 3 b side of the semiconductor substrate 3, separated from each p-type semiconductor region 5. ing. The n-type semiconductor region 7 is made of, for example, Si and has a thickness of, for example, 1.5 μm. The n-type semiconductor region 7 includes an impurity (for example, phosphorus) and is set to have an impurity concentration higher than that of the semiconductor substrate 3 (for example, 1 × 10 ¹⁸ / cm ³ ).

An insulating film 21 is formed on substantially the entire back surface 3b of the semiconductor substrate 3 by, for example, a well-known CVD (chemical vapor deposition) method, vapor deposition method, sputtering method, or thermal oxidation method. The insulating film 21 is made of, for example, SiO ₂ (oxide film) or SiN (nitride film), and a plurality of contact holes 23 are provided. An electrode film 25 is disposed on the insulating film 21 at the position where each of the p-type semiconductor region 5 and the n-type semiconductor region 7 is disposed as viewed from the direction perpendicular to the back surface 3 b of the semiconductor substrate 3. The electrode film 25 is made of a metal material (for example, Al), is disposed so as to close the contact hole 23, and is physically and electrically connected to the p-type semiconductor region 5 or the n-type semiconductor region 7.

  An electrode pad 29 is formed on the electrode film 25 by sequentially plating, for example, Ni and Au. An interlayer insulating film 27 is disposed so as to cover the electrode film 25 excluding the portion where the electrode pad 29 is formed and the region between the adjacent electrode films 25. The interlayer insulating film 27 is formed of an insulating resin such as polyimide, thereby suppressing adjacent electrode films 25 from being electrically connected to each other.

  A bump electrode 31 is disposed on the electrode pad 29 at the approximate center of each p-type semiconductor region 5 when viewed from the direction perpendicular to the back surface 3 b of the semiconductor substrate 3. A bump electrode 33 is disposed on the electrode pad 29 in the approximate center of the region between the four p-type semiconductor regions 5 adjacent to each other when viewed from the direction perpendicular to the back surface 3 b of the semiconductor substrate 3. The bump electrodes 31 and 33 are physically and electrically connected to a wiring board 81 to be described later. The bump electrodes 31 and 33 are made of a metal material (for example, solder), and are formed by, for example, a solder paste screen printing method.

An accumulation region 41 is disposed on substantially the entire surface of the semiconductor substrate 3 on the surface 3a side. The accumulation region 41 is made of, for example, Si and has a thickness of, for example, 1.0 μm. The accumulation region 41 is an n-type semiconductor region containing an impurity (for example, phosphorus or the like), and its concentration is, for example, 1 × 10 ¹⁵ / cm ³ .

An insulating film 43 is disposed on a substantially entire surface of the surface 3a of the semiconductor substrate 3 as a coating film (protective film) for the surface 3a. A surface 43a of the insulating film 43 opposite to the semiconductor substrate 3 constitutes a light incident surface of the photodiode array 1a. The insulating film 43 is, for example, a light transmission film. The insulating film 43 is made of, for example, SiO ₂ (oxide film) or SiN (nitride film), and the thickness thereof is, for example, 0.1 μm. The insulating film 43 is formed by, for example, a well-known CVD method, vapor deposition method, sputtering method, or thermal oxidation method. The insulating film 43 includes a portion on the surface 3a of the semiconductor substrate 3 corresponding to a position where the modified region 50 is disposed and the modified region 50 when viewed from a direction perpendicular to the back surface 3b of the semiconductor substrate 3. And a portion on the surface 3a of the semiconductor substrate 3 corresponding to the position that is not.

  Next, the modified region 50 will be described. The modified region 50 is disposed only in the region 35 and is not disposed in the region 36. In the region 35, the modified region 50 is disposed only in the region 37 having the region 37a between the p-type semiconductor regions 5 adjacent in the row direction and the region 37b between the p-type semiconductor regions 5 adjacent in the column direction. ing. The modified region 50 is not disposed in the region 38 surrounded by the four adjacent p-type semiconductor regions 5. The modified region 50 is formed in each of the regions 37a and 37b as a linear portion continuously extending in a direction intersecting with the arrangement direction of the p-type semiconductor region 5. The linear portion is formed by a plurality of portions having a longitudinal direction substantially parallel to the side surface of the semiconductor substrate 3 and a short direction perpendicular to the longitudinal direction.

  The “region between adjacent p-type semiconductor regions 5” means a region inside the semiconductor substrate 3 located between adjacent p-type semiconductor regions 5 when viewed from the direction perpendicular to the back surface 3b of the semiconductor substrate 3. To do. The “region surrounded by the four adjacent p-type semiconductor regions 5” means the inside of the semiconductor substrate 3 surrounded by the four adjacent p-type semiconductor regions 5 when viewed from the direction perpendicular to the back surface 3 b of the semiconductor substrate 3. Means the area.

  The modified region 50 is formed in a substantially half region on the surface 3a side of the semiconductor substrate 3 between the surface 3a of the semiconductor substrate 3 and each n-type semiconductor region 7, and the surface 3a of the semiconductor substrate 3 and the n-type semiconductor region 3 are formed. They are arranged without reaching the semiconductor region 7. The modified region 50 is disposed without reaching the depletion layer formed integrally by spreading from the pn junctions 11 of the two adjacent p-type semiconductor regions 7.

  The modified region 50 has a predetermined depth position from the surface 3a in the semiconductor substrate 3 (the region on the surface 3a side in the thickness direction of the semiconductor substrate 3 is preferably 10 to 60%, more preferably 10 to 45%, and more preferably 10 to 30%. % Is more preferable). Further, the end of the modified region 50 on the surface 3a side is located at a predetermined depth from the surface 3a (for example, 145 μm or less is preferable, 75 μm is more preferable, and 20 μm is more preferable).

  The cross section obtained by cutting the linear portion of the modified region 50 along a plane perpendicular to the longitudinal direction has an elliptical shape having a major axis in the thickness direction of the semiconductor substrate 3 and has a minor axis width of, for example, 3 to 4 μm. Is formed. The modified region 50 is formed over the entire region irradiated with the laser beam La by, for example, multiphoton absorption by irradiating the laser beam La with the focusing point F inside the semiconductor substrate 3 as will be described later. Yes. In addition, the condensing point F is a location where the laser beam La is condensed.

  The photodiode array 1a having the above configuration performs the following operation. When the light L1 is incident from the surface 43a side of the insulating film 43, the light L1 passes through the insulating film 43 and reaches the semiconductor substrate 3, the p-type semiconductor region 5, and the n-type semiconductor region 7. The carriers generated by each wavelength component of the light L1 drift according to the electric field inside the semiconductor substrate 3, the p-type semiconductor region 5, and the n-type semiconductor region 7, and diffuse when there is no electric field.

  When carriers generated by each wavelength component of the light L1 drift or diffuse between adjacent p-type semiconductor regions 5, they are trapped in the modified region 50 and disappear by recombination. Carriers that have not been trapped in the modified region 50 and have reached the pn junction 11 are taken out from the bump electrodes 31 and 33 as photocurrents. With this photocurrent, each photodiode 13 outputs an electrical signal corresponding to the light wavelength component of the light L1.

  Next, a manufacturing method of the photodiode array 1a described above will be described with reference to FIGS. 3 and 4 are schematic views showing a cross-sectional configuration for explaining a manufacturing process of the photodiode array 1a according to the first embodiment.

  First, a workpiece 61 is prepared in which structural units having the same configuration as the photodiode array 1a shown in FIG. 2 are arranged in a matrix except that the modified region 50 is not formed. Then, as shown in FIG. 3A, a dicing tape (holding member) 63 is attached to the workpiece 61.

  Next, the laser beam La is set to a condition where multiphoton absorption occurs, and as shown in FIG. 3B, at a predetermined depth position in a region between adjacent p-type semiconductor regions 5 inside the semiconductor substrate 3. On the other hand, the laser beam La is irradiated from the surface 3a side of the semiconductor substrate 3 with the focusing point F aligned. The modified region 50 is formed to expand from the condensing point F in the direction of the surface 3 a of the semiconductor substrate 3, so that the cross section has an elliptical shape having a major axis in the thickness direction of the semiconductor substrate 3. Note that the depth position of the modified region 50 is adjusted by, for example, adjusting the relative positional relationship between the semiconductor substrate 3 and the optical system that irradiates the laser light La so that the condensing point F is located in the thickness direction of the semiconductor substrate 3. It is possible to adjust by moving relative to 3.

Here, the multiphoton absorption will be briefly described. Photon energy hν is smaller than the band gap E _G of absorption of the material, the optically transparent. Therefore, if it is hv> E _G is the absorption occurs in the material. However, it is optically transparent, when very the intensity of the laser light largely, Nhnyu> of E _G condition (n = 2,3,4, ···) absorption occurs in the material in. This phenomenon is called multiphoton absorption. In the case of pulsed waves, the intensity of laser light is determined by the peak power density of the focus point of the laser beam (W / cm ^2), for example, the peak power density multiphoton at ^{1 × 10 8 (W / cm} 2) or more conditions Absorption occurs. The peak power density is obtained by (energy per one pulse of laser light at a condensing point) / (laser beam cross-sectional area of laser light × pulse width). In the case of a continuous wave, the intensity of the laser beam is determined by the electric field intensity (W / cm ² ) at the condensing point of the laser beam.

  In the laser processing according to the first embodiment, the modified region 50 is not formed by causing the semiconductor substrate 3 to generate heat by the semiconductor substrate 3 absorbing the laser light La. The laser beam La is transmitted through the semiconductor substrate 3 and multiphoton absorption is generated inside the semiconductor substrate 3 to form the modified region 50. Therefore, since the laser beam La is hardly absorbed at the surface 3a of the semiconductor substrate 3 and the surface 43a of the insulating film 43, the surface 3a of the semiconductor substrate 3 and the surface 43a of the insulating film 43 are not melted.

  As an example of the modified region 50 formed by multiphoton absorption in the first embodiment, there is a melting processing region.

In this case, the laser beam La is focused at the condensing point F inside the semiconductor substrate 3, and the electric field intensity at the condensing point F is 1 × 10 ⁸ (W / cm ² ) or more and the pulse width is 1 μs or less. Irradiate under conditions. Thereby, the inside of the semiconductor substrate 3 is locally heated by multiphoton absorption. By this heating, a melt processing region is formed inside the semiconductor substrate 3.

The melting treatment region means at least one of a region once solidified after melting, a region in a molten state, and a region in a state of being resolidified from melting. It can also be said that the melt treatment region is a phase-change region or a region where the crystal structure is changed. It can be said that the melt-processed region is a region in which one structure is changed to another structure in a single crystal structure, an amorphous structure, or a polycrystalline structure. In other words, for example, a region changed from a single crystal structure to an amorphous structure, a region changed from a single crystal structure to a polycrystalline structure, and a region changed from a single crystal structure to a structure including an amorphous structure and a polycrystalline structure. To do. When the semiconductor substrate 3 has a silicon single crystal structure, the melt processing region has, for example, an amorphous silicon structure. In addition, as an upper limit of an electric field strength, it is 1 * 10 < ¹² > (W / cm < ² >), for example. For example, the pulse width is preferably 1 to 200 ns.

  Next, a continuous linear reforming region 50 is formed by moving the condensing point F relative to the semiconductor substrate 3 along a planned formation line (not shown). The formation planned line is an imaginary line extending in a straight line, and, for example, along the adjacent p-type semiconductor region 5 on the surface 3a side of the semiconductor substrate 3 so as to correspond to the formation position of the modified region 50. Has been placed. Similarly, the modified region 50 is formed in the region between the adjacent p-type semiconductor regions 5 by relatively moving the condensing point F with respect to the semiconductor substrate 3 along other planned formation lines. As a result, the workpiece 65 in which the modified region 50 is arranged is obtained.

  Next, as shown in FIG. 3C, the laser beam La is irradiated with the focal point F aligned with the cutting position of the semiconductor substrate 3. Then, the condensing point F is moved relative to the semiconductor substrate 3 in the thickness direction of the semiconductor substrate 3, and the condensing point F is moved relative to the semiconductor substrate 3 along a planned cutting line (not shown). Then, the melt processing region is formed inside the semiconductor substrate 3 so as to reach the back surface 3 b of the semiconductor substrate 3 and the front surface 43 a of the insulating film 43. Note that the planned cutting line is a virtual line extending in a straight line, and is arranged, for example, on the surface 3a side of the semiconductor substrate 3 so as to correspond to the cutting position.

  Then, the dicing tape 63 is expanded while the dicing tape 63 and the workpiece 65 are neutralized. As a result, since the dicing tape 63 is in an expanded state, as shown in FIG. 4A, the workpiece 65 is cut along the planned cutting line using the melting region as a starting point of cutting, and a plurality of processings are performed. The object 65a is obtained.

  Next, after each dicing tape 63 is peeled off by irradiating each work object 65a with UV, one of the obtained work objects 65a is taken out as shown in FIG. 4B. Then, as shown in FIG. 4C, by forming bump electrodes 31 and 33 at predetermined positions by, for example, a solder paste screen printing method, the photodiode array 1a is obtained.

  As described above, in the first embodiment, the modified region 50 is formed in the region 37 so as to extend in the direction intersecting the arrangement direction of the adjacent p-type semiconductor regions 5. In this case, carriers generated by the incidence of the light L1 and diffusing into the region 37 are trapped in the modified region 50, and crosstalk can be suppressed.

  In the first embodiment, the modified region 50 is not formed in the region 38. In this case, in the region 38, the decrease in the mechanical strength of the semiconductor substrate 3 is suppressed. Therefore, even when an external force is applied to the semiconductor substrate 3, it is possible to suppress the occurrence of cracks in the region 38. Further, even when a crack occurs in the modified region 50 of the region 37, the growth of the crack in the region 38 is suppressed. As a result, the cracks in the modified region 50 are suppressed from growing over a wide area of the semiconductor substrate 3. Accordingly, it is possible to suppress a decrease in mechanical strength of the semiconductor substrate 3 due to the formation of the modified region.

  By the way, when the modified regions 50 formed in the regions 37a and 37b respectively extend to the region 38 and intersect with each other, when an external force is applied to the semiconductor substrate 3, the stress is particularly concentrated at the intersecting portion. In this case, the reformed region 50 is likely to be cracked starting from the intersection. Furthermore, if the mechanical strength inside the semiconductor substrate 3 in contact with the intersecting portion is not sufficient, the semiconductor substrate 3 is cracked. However, in the first embodiment, since the modified region 50 is not formed in the region 38, the formation of the intersection of the modified region 50 in the region 38 is suppressed. Therefore, it is possible to suppress the occurrence of cracks in the modified region 50 and the semiconductor substrate 3 in the region 38.

  In the first embodiment, the semiconductor substrate 3 includes a region 35 in which the plurality of p-type semiconductor regions 5 are disposed, and a region 36 that surrounds the region 35 and whose outer edge forms the outer edge of the semiconductor substrate 3. In the region 36, no modified region is formed. In this case, the formation of a region with reduced mechanical strength in the region 36 is suppressed. For this reason, even when an external force is applied to the region 36 by dicing using a blade or the like, the occurrence of cracks in the region 36 is suppressed. Therefore, it is possible to further suppress a decrease in mechanical strength of the semiconductor substrate 3 due to the formation of the modified region.

[Second Embodiment]
The configuration of the photodiode array 91 according to the second embodiment will be described with reference to FIGS. FIG. 5 is a plan view showing a photodiode array 91 according to the second embodiment. FIG. 6 is a schematic diagram showing a cross-sectional configuration along the line VI-VI in FIG.

  The front-illuminated photodiode array 91 according to the second embodiment includes an n-type semiconductor substrate 3, a p-type semiconductor region 5, and an n-type semiconductor region 7, as shown in FIGS. Yes.

  The semiconductor substrate 3 has a front surface (one surface) 3c and a back surface (other surface) 3d facing each other. The surface 3c is an incident surface for the light L1, and is also a signal output surface. The semiconductor substrate 3 is a substrate formed in a rectangular shape and has a modified region 50 inside.

An n-type semiconductor region 93 is disposed on substantially the entire surface of the semiconductor substrate 3 on the back surface 3d side. The n-type semiconductor region 93 includes an impurity (for example, phosphorus) and is set to have a higher impurity concentration (for example, 1 × 10 ¹⁸ / cm ³ ) than the semiconductor substrate 3. The semiconductor substrate 3 is the same as that of the first embodiment in other points.

  The p-type semiconductor regions 5 are two-dimensionally arranged in a matrix (for example, 2 × 3) on the surface 3 c side of the semiconductor substrate 3. Each p-type semiconductor region 5 is arranged away from each other, and is formed in a rectangular shape, for example. The p-type semiconductor region 5 is the same as that of the first embodiment in other points.

  The n-type semiconductor region 7 is arranged between the adjacent p-type semiconductor regions 5 on the surface 3c side of the semiconductor substrate 3 so as to be separated from each p-type semiconductor region 5 and surround each p-type semiconductor region 5. . The n-type semiconductor region 7 is the same as that of the first embodiment in other points.

An insulating film 21 is disposed on substantially the entire surface 3 c of the semiconductor substrate 3. The insulating film 21 is made of, for example, SiO ₂ (oxide film) or SiN (nitride film), and a contact hole 23 is provided. An electrode wiring 95 is disposed on the insulating film 21 at the end in the long side direction of each p-type semiconductor region 5.

  The electrode wiring 95 is formed of a metal material (for example, Al). The electrode wiring 95 is substantially T-shaped and has a first portion 95a and a second portion 95b. The first portion 95 a is disposed so as to close the contact hole 23 and extends in the short side direction of the p-type semiconductor region 5. The substantially center of the first portion 95a is joined to one end side of the second portion 95b. The other end side of the second portion 95 b is joined to an anode electrode 97 a disposed on the insulating film 21 on one end side in the short side direction of the semiconductor substrate 3.

  A metal film 99 made of a metal material (for example, Al) is disposed on the insulating film 21 corresponding to the position where the n-type semiconductor region 7 is disposed. The metal film 99 is disposed so as to close the contact hole 23 of the insulating film 21 and is connected to the n-type semiconductor region 7. On the corner of the metal film 99, the cathode electrode 97b is disposed.

  The modified region 50 is different from the first embodiment in the depth position inside the semiconductor substrate 3, and is otherwise the same as the first embodiment. The modified region 50 is formed without reaching the back surface 3 d of the semiconductor substrate 3 and the n-type semiconductor region 7. The modified region 50 has a predetermined depth position on the surface 3c side in the thickness direction of the semiconductor substrate 3 (preferably the region on the surface 3c side is 10 to 60%, more preferably 10 to 45%, still more preferably 10 to 30%. .) Is formed. Further, the end of the modified region 50 on the surface 3c side is formed at a predetermined depth from the surface 3c (for example, 145 μm or less is preferable, 75 μm is more preferable, and 20 μm is more preferable).

  As described above, in the second embodiment, similarly to the first embodiment, the modified region 50 is formed in the region 37 so as to extend in a direction intersecting the arrangement direction of the adjacent p-type semiconductor regions 5. Therefore, crosstalk can be suppressed. In addition, since the modified region 50 is not formed in the region 38, it is possible to suppress a decrease in mechanical strength of the semiconductor substrate 3 due to the formation of the modified region.

  By the way, in 2nd Embodiment, it is preferable to form the modified area | region 50 in the surface 3c vicinity of the semiconductor substrate 3 from a viewpoint of suppressing crosstalk. In this case, since the electric field strength is high at the corner of each p-type semiconductor region 5, breakdown occurs when the modified region 50 is brought close to the corner. However, in the second embodiment, since the modified region 50 is not formed in the region 38 close to the corner portion, it is possible to suppress breakdown.

  The preferred embodiments of the photodiode array of the present invention have been described above. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  The number and shape of the modified regions 50, the depth positions from the surfaces 3a and 3c of the semiconductor substrate 3, and the width in the minor axis direction of the cross section are not limited to the above embodiment. For example, when the width of the short axis direction in the cross section of the modified region 50 is wider than that in the above embodiment (for example, 6 to 7 μm), the modified region 50 is loaded when an external force is applied to the semiconductor substrate 3. Since the stress is dispersed without locally concentrating, a decrease in mechanical strength of the semiconductor substrate 3 can be suppressed.

  The modified region 50 is not limited to being not formed in the region 38. For example, a photodiode array 1b as shown in FIG. 7 may be used. The region 37 of the photodiode array 1b is irradiated with a laser beam La at a predetermined position of the region 37 and irradiated with the laser beam La, so that the region 37 of the photodiode array 1b extends in a direction intersecting the arrangement direction of the adjacent p-type semiconductor regions 5. A quality region (first modified region) 50 is formed. Further, a modified region (second modified region) 52 is formed in the region 38 by irradiating the laser beam La with the focal point F at a predetermined position in the region 38. The modified region 50 and the modified region 52 are located apart from each other.

  In the photodiode array 1b, the plurality of p-type semiconductor regions 5 are two-dimensionally arranged in a matrix (for example, 4 × 4). The modified region 50 is formed in a continuous linear shape in a region 37a between the p-type semiconductor regions 5 adjacent in the row direction and a region 37b between the p-type semiconductor regions 5 adjacent in the column direction. The modified region 52 is formed in a region 38 between the p-type semiconductor regions 5 adjacent to each other in the direction intersecting the row direction and the column direction. The modified region 52 is formed in one continuous straight line extending in the thickness direction of the semiconductor substrate 3 in the approximate center of the region 38. Note that the modified region 50 and the modified region 52 arranged in a straight line may be formed by a single relative movement of the condensing point F with respect to the semiconductor substrate 3, and are formed by separate relative movements. Also good.

  In the photodiode array 1b, a modified region 50 is formed in the region 37, and a modified region 52 is formed in the region 38. In this case, carriers generated by the incidence of the light L1 and diffusing in the regions 37 and 38 are trapped in the modified regions 50 and 52, respectively, and crosstalk can be suppressed.

  In the photodiode array 1b, the modified region 50 and the modified region 52 are formed apart from each other. In this case, in the region between the modified region 50 and the modified region 52, a decrease in the mechanical strength of the semiconductor substrate 3 is suppressed. Therefore, even when a crack occurs in the modified region 50 or the modified region 52, the growth of the crack in the region between the modified region 50 and the modified region 52 is suppressed. Thereby, the crack of the modified region is prevented from growing over a wide area of the semiconductor substrate. Accordingly, it is possible to suppress a decrease in mechanical strength of the semiconductor substrate 3 due to the formation of the modified region.

  Further, in the photodiode array 1b, since the modified region 50 and the modified region 52 are formed apart from each other, the formation of an intersection in the region 38 is suppressed. Therefore, it is possible to suppress the occurrence of cracks in the modified regions 50 and 52 and the semiconductor substrate 3 in the region 38.

  Further, a photodiode array 1c as shown in FIG. 8 may be used. In the photodiode array 1c, the p-type semiconductor regions 5 are two-dimensionally arranged in a matrix (for example, 4 × 4). Further, among the two-dimensionally arranged p-type semiconductor regions 5, four adjacent p-type semiconductor regions 5 are divided into p-type semiconductor regions adjacent to each other in the row direction (first and second second-conductivity-type semiconductor regions). 5a, 5b, a p-type semiconductor region (third second conductivity type semiconductor region) 5c adjacent to the p-type semiconductor region 5a in the column direction, and a p-type semiconductor region 5a in the direction intersecting the row direction and the column direction. And a p-type semiconductor region (fourth second conductivity type semiconductor region) 5d adjacent to each other, a region 37c between the p-type semiconductor regions 5a, 5b and the p-type semiconductor regions 5c, 5d A modified region (first modified region) 50a extending continuously in the row direction is formed by aligning the condensing point F at a predetermined position of the region 37c and irradiating the laser beam La, and a p-type semiconductor is formed. A region 37d between the regions 5a and 5b, a p-type semiconductor region 5c, In the region 37e between d, a modified region (second modified region) 50b extending in the column direction is obtained by irradiating the laser beam La with the condensing point F at a predetermined position of the regions 37d and 37e. Is formed.

  In the four adjacent p-type semiconductor regions 5, the modified region 50a and the modified region 50b are located away from each other. The modified regions 50a and 50b are arranged so that the respective longitudinal directions thereof alternately face the row direction and the column direction in the arrangement of the p-type semiconductor regions 5 for each region including the four adjacent p-type semiconductor regions 5. Yes. Note that the regions including the four adjacent p-type semiconductor regions 5 may be arranged adjacent to each other such that the longitudinal directions of the modified regions 50a and 50b face the same direction.

  In the photodiode array 1c, one of the modified regions 50a and 50b is formed between each of the p-type semiconductor regions 5a to 5d. As a result, carriers generated by the incidence of the light L1 and diffused between the p-type semiconductor regions 5a to 5d are trapped in either the modified region 50a or the modified region 50b, thereby suppressing crosstalk. can do.

  In the photodiode array 1c, the modified region 50a and the modified region 50b are formed apart from each other. In this case, a decrease in the mechanical strength of the semiconductor substrate 3 is suppressed in the region between the modified region 50a and the modified region 50b. Therefore, even when a crack occurs in the modified region 50a or the modified region 50b, the growth of the crack is suppressed in the region between the modified region 50a and the modified region 50b. Thereby, the crack of the modified region is prevented from growing over a wide area of the semiconductor substrate 3. Accordingly, it is possible to suppress a decrease in mechanical strength of the semiconductor substrate 3 due to the formation of the modified region.

  Moreover, in the photodiode array 1c, since the modified region 50a and the modified region 50b are formed apart from each other, the formation of an intersection is suppressed. Therefore, the generation of cracks in the modified regions 50a and 50b and the semiconductor substrate 3 can be suppressed.

  Further, the region 36 is not limited to the case where the modified region is not formed. For example, a photodiode array 1d as shown in FIG. 9 may be used. In the region 36 of the photodiode array 1d, a modified region 54 is formed by irradiating the laser beam La with the focal point F aligned with a predetermined position of the region 36. A plurality of modified regions 54 are formed extending in the direction along the outer edge of the semiconductor substrate 3. The plurality of modified regions 54 surround the region 35. Each reforming region 54 is formed in a continuous linear shape and is spaced apart from each other. The plurality of modified regions 54 may surround the outer periphery of the region 35 by connecting the modified regions 54 to each other.

  In the photodiode array 1d, a modified region 54 is formed in the region 36. In this case, carriers generated between the side surface of the semiconductor substrate 3 and the modified region 54 due to the incidence of the light L1 and carriers generated due to crystal defects on the side surface of the semiconductor substrate 3 are trapped in the modified region 54. The Rukoto. Thereby, since it is further suppressed that the carrier reaches the p-type semiconductor region 5 arranged in the region 35, crosstalk can be further suppressed.

  In the photodiode array 1d, the modified region 50 and the modified region 54 are formed apart from each other. In the region between the reforming region 50 and the reforming region 54, the decrease in mechanical strength is suppressed. Therefore, even if a crack occurs in either the modified region 50 or the modified region 54, the growth of cracks is suppressed in the region between the modified region 50 and the modified region 54. . Therefore, it is possible to suppress the crack in the modified region from growing in a wide area of the semiconductor substrate 3 while suppressing the crosstalk as described above. Further, the formation of an intersecting portion by the modified region 50 and the modified region 54 is suppressed. Therefore, even when an external force is applied to the region 36, it is possible to suppress the occurrence of cracks in the region 36.

  Further, a photodiode array 1e as shown in FIG. 10 may be used. In the photodiode array 1e, a modified region 56 is formed in the region 36. The modified region 56 has a plurality of first portions 56a and a plurality of second portions 56b. The plurality of first and second portions 56 a and 56 b surround the region 35. The first portions 56 a are formed in a continuous linear shape extending in the direction along the outer edge of the semiconductor substrate 3 and are arranged apart from each other. Each second portion 56b is formed in a continuous linear shape extending in a direction intersecting the outer edge of the semiconductor substrate 3 in a region between the adjacent first portions 56a and to the side surface of the semiconductor substrate 3. It extends. Each second portion 56 b is arranged apart from the first portion 56 a and is continuous with the modified region 50 between the adjacent p-type semiconductor regions 5.

  In the photodiode array 1e, the light is generated due to carriers generated between the side surface of the semiconductor substrate 3 and the first portion 56a formed in the region 36 due to the incidence of the light L1 and crystal defects on the side surface of the semiconductor substrate 3. Carrier to be trapped by the modified region 56. Thereby, since it is further suppressed that the carrier reaches the p-type semiconductor region 5 arranged in the region 35, crosstalk can be further suppressed.

  Further, in the photodiode array 1e, since the second portion 56b is located away from the first portion 56a, the mechanical strength decreases in the region between the first portion 56a and the second portion 56b. Is suppressed. Therefore, even if a crack occurs in any of the first and second portions 56a and 56b, the growth of the crack is suppressed in the region between the first portion 56a and the second portion 56b. It will be. Therefore, it is possible to suppress the crack in the modified region from growing in a wide area of the semiconductor substrate 3 while suppressing the crosstalk as described above. Further, in the photodiode array 1e, the formation of an intersecting portion by the first portion 56a and the second portion 56b is suppressed. Therefore, even if an external force is applied, it is possible to suppress the occurrence of cracks in the region 36.

  The modified region 50 does not reach the surface 3a of the semiconductor substrate 3 in the photodiode arrays 1a to 1e, and the end on the surface 3a side (light incident surface side) is located inside the semiconductor substrate 3. It is not limited to. For example, the modified region 50 reaches the surface 3 a of the semiconductor substrate 3 and is arranged so that the end on the light incident surface side is located between the surface 3 a of the semiconductor substrate 3 and the surface 43 a of the insulating film 43. It may be.

  In addition, the modified region 50 is not limited to be formed in the region between the adjacent p-type semiconductor regions 5 so as to extend in a direction intersecting the arrangement direction of the adjacent p-type semiconductor regions 5. Alternatively, two or more may be formed apart from each other in the arrangement direction of the p-type semiconductor region 5. The two or more modified regions 50 may have the same or different depth positions from the surfaces 3 a and 3 c of the semiconductor substrate 3.

  The modified region 50 is not limited to being formed in a continuous linear shape, and may be an intermittent linear shape. For example, the modified region 50 is formed in an intermittent linear shape by arranging a plurality of portions having a longitudinal direction and a short direction perpendicular to the longitudinal direction so that the longitudinal directions are separated from each other in the same direction. It may be. Moreover, the modified region 50 is formed in two intermittent straight lines, and each of the above portions may be formed alternately without facing each other.

  The modified region 50 is not limited to being formed only by a linear portion having an elliptical cross section. The modified region 50 may include a linear portion extending from the linear portion in the thickness direction of the semiconductor substrate 3. Further, the modified region 50 may be formed by modification other than multiphoton absorption.

  Further, the number, material, shape, thickness, impurity concentration, and impurity type of the semiconductor substrate 3, the p-type semiconductor region 5, and the n-type semiconductor region 7 are not limited to the above-described embodiments. For example, each p-type semiconductor region 5 is not limited to being formed in a square shape, and may be formed in a polygonal shape such as a hexagon.

  The semiconductor substrate 3, the p-type semiconductor region 5 and the n-type semiconductor region 7 may contain an impurity having a conductivity type opposite to that of the above-described embodiment. The semiconductor substrate 3 is not limited to being formed of Si. For example, the semiconductor substrate 3 and the p-type semiconductor region 5 may be formed of the same or different compound semiconductors (for example, GaAs or GaSb). Good.

  The manufacturing method of the photodiode array according to the above embodiment is not limited to cutting the workpiece 65 by forming a melt processing region by laser processing, and cutting the workpiece 65 using a blade. May be. In this case, the workpiece 65 shown in FIG. 3B is irradiated with UV, and the dicing tape 63 is peeled off as shown in FIG. Next, after transferring the planned cutting line to the back surface 3b side of the semiconductor substrate 3, a dicing tape 63 is attached to the surface 43a of the insulating film 43 as shown in FIG. And as shown in FIG.11 (c), the process target object 65 is cut | disconnected by the braid | blade 67 along a cutting plan line. Furthermore, a plurality of workpieces 65a similar to those shown in FIG. 4B can be obtained by sucking and cleaning dust or the like using an ion air cleaning device or a suction device.

[Radiation detector]
With reference to FIG. 12, the structure of the radiation detector 100 which concerns on this embodiment is demonstrated. FIG. 12 is a schematic diagram showing a cross-sectional configuration of the radiation detector 100 according to the present embodiment.

  As shown in FIG. 12, the radiation detector 100 includes the photodiode array 1a, a scintillator 73, and a wiring board 81.

  The scintillator 73 is disposed on the insulating film 43. The scintillator 73 includes a scintillator layer 75 disposed on the insulating film 43 and a moisture-resistant protective film 77 disposed on the scintillator layer 75.

  The scintillator layer 75 is configured such that a plurality of columnar crystals that convert incident light (radiation) into light of a predetermined wavelength are in contact with each other. The scintillator layer 75 is formed by vapor-depositing CsI, CsBr or the like on the surface 43a of the insulating film 43 by a resistance heating method of about room temperature to about 150 ° C. The scintillator layer 75 has a thickness of, for example, 400 μm.

  The moisture-resistant protective film 77 prevents the scintillator layer 75 from being deteriorated due to the absorption of moisture and the characteristics from being deteriorated. The moisture-resistant protective film 77 has a thickness of 10 μm, for example. The moisture-resistant protective film 77 is a resin layer made of a xylene-based resin such as polyparaxylylene, polymonochloroparaxylylene, etc., which has high X-ray permeability and extremely low water vapor and gas permeability. The moisture-resistant protective film 77 is formed by using a CVD method or the like.

  For example, a glass substrate is used as the wiring substrate 81, and has a signal input surface 81a and a signal output surface 81b facing each other. The wiring board 81 has a plurality of through-holes 81c reaching from the signal input surface 81a to the signal output surface 81b. A plurality of through holes 81 c are formed at the same pitch as the bump electrodes 31 and 33. A conductive member 83 is provided in each through hole 81c. The conductive member 83 is disposed on the inner wall of each through-hole 81c and electrically connects the signal input surface 81a and the signal output surface 81b with each other, and the through-hole 81c on the signal input surface 81a. The input portion 83a is disposed at the outer peripheral portion, and the output portion 83b is disposed at the outer peripheral portion of each through hole 81c on the signal output surface 81b.

  The wiring substrate 81 is disposed above the back surface 3 b of the semiconductor substrate 3, and the input unit 83 a is connected to the bump electrodes 31 and 33. A bump electrode 85 is disposed on each output portion 83b. The wiring substrate 81 is connected to, for example, an external substrate 87 described later via the bump electrode 85.

  The radiation detector 100 having the above configuration performs the following operation. When light (radiation) L1 such as X-rays enters the scintillator 73, scintillation light having a predetermined wavelength corresponding to the light L1 is generated in the scintillator layer 75, and the scintillation light enters the photodiode array 1a.

  When scintillation light enters from the surface 3 a side of the photodiode array 1, the scintillation light passes through the insulating film 43 and reaches the semiconductor substrate 3, the p-type semiconductor region 5, and the n-type semiconductor region 7. The carriers generated by the scintillation light drift according to the electric field inside the semiconductor substrate 3, the p-type semiconductor region 5, and the n-type semiconductor region 7, and diffuse when there is no electric field.

  When carriers generated by scintillation light drift or diffuse between adjacent p-type semiconductor regions 5, they are trapped in the modified region 50 and disappear by recombination. Carriers that have not been trapped in the modified region 50 and have reached the pn junction 11 are taken out from the bump electrodes 31 and 33 as photocurrents. With this photocurrent, each photodiode 13 outputs an electrical signal corresponding to the light wavelength component of the light L1.

  Next, the manufacturing method of the radiation detector 100 mentioned above is demonstrated using FIG. FIG. 13 is a schematic diagram showing a cross-sectional configuration for explaining a manufacturing process of the radiation detector 100 according to the present embodiment.

  First, the photodiode array 1a is manufactured by the manufacturing method described above. Next, after producing a wiring board 81 having a configuration as shown in FIG. 12, the wiring board 81 is connected to the photodiode array 1a by, for example, flip chip mounting. In flip-chip mounting, first, alignment of the photodiode array 1a and the wiring substrate 81 is performed so that the bump electrodes 31 and 33 and the input portion 83a face each other. After this alignment, the bump electrodes 31 and 33 and the input portion 83a are pressed against each other and bump-bonded by thermocompression bonding, ultrasonic waves, or the like. As described above, the wiring substrate 81 is connected to the photodiode array 1a via the bump electrodes 31 and 33 as shown in FIG.

  Next, the scintillator layer 75 is formed by evaporating CsI, CsBr or the like on the surface 43a of the insulating film 43 by, for example, resistance heating, and growing it as a columnar crystal. Further, a moisture-resistant protective film 77 is formed so as to cover the scintillator layer 75 by, for example, a CVD method. Thus, the scintillator 73 is formed on the insulating film 43, and the radiation detector 100 is obtained as shown in FIG.

  Note that the external substrate 87 may be further flip-chip mounted by the bump electrode 85 of the wiring substrate 81 to form the radiation detector 200 having the configuration as shown in FIG. In the external substrate 87, for example, a plurality of internal wirings 89b formed by embedding a conductive member in the external substrate 87, and an input portion disposed on the outer periphery of the conductive member exposed on the signal input surface 89a is arranged. By connecting the input portion 89a to the bump electrode 85, the wiring substrate 81 and the external substrate 87 are connected.

  As described above, since the photodiode array 1a is used in the present embodiment, it is possible to suppress a decrease in mechanical strength of the semiconductor substrate 3 due to the formation of the modified region while suppressing crosstalk. .

  The preferred embodiments of the radiation detector of the present invention have been described above. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  In the radiation detector 100, a barrier layer may be disposed between the insulating film 43 and the scintillator 73. The barrier layer is a resin layer made of, for example, polyimide or the like, which has a corrosion prevention (moisture prevention) effect, for example. The barrier layer is formed by applying and curing, for example, by spin coating.

  Further, the scintillator 73 is not limited to the one in which the scintillator layer 75 is directly deposited on the insulating film 43 or the barrier layer. For example, a scintillator in which a scintillator layer made of CsI, CsBr, or the like is formed on a radiation transmissive substrate (for example, aluminum, amorphous carbon, FOP (fiber optic plate)) by a resistance heating method at about room temperature to 150 ° C. is used. Also good. In this case, the surface opposite to the surface on which the scintillator layer of the radiation transmissive substrate is disposed and the surface 43a of the insulating film 43 and the light incident surface of the barrier layer are transparent (light transmissive) resin (for example, epoxy resin). , Acrylic resin).

  Further, as the scintillator 73, a panel type scintillator may be used. FIG. 14 is a schematic diagram showing a cross-sectional configuration of a radiation detector 300 using a panel-type scintillator. The radiation detector 300 includes a transparent (light transmitting) resin layer 72 disposed on the insulating film 43 and a scintillator panel 73 disposed on the transparent resin layer 72.

  The transparent resin layer 72 is formed of an optical resin having adhesiveness (for example, polyimide). The transparent resin layer 72 is disposed so as to fill a gap between the insulating film 43 and the scintillator panel 73. As a result, when light (radiation) enters the scintillator 73 and scintillation light having a predetermined wavelength is generated, the scintillation light is not reflected by the gap between the insulating film 43 and the scintillator panel 73 and the photodiode array 1. Is incident on.

The scintillator panel 73 includes a scintillator layer 75 disposed on the transparent resin layer 72 and a moisture-resistant protective film 77 that covers the scintillator layer 75. The scintillator layer 75 has a flat plate shape. The scintillator layer 75 is made of GOS (gadolinium sulfate) such as Gd ₂ O ₂ S: Pr or Gd ₂ O ₂ S: Tb, CsI doped with Tl, CdWO ₄ (CWO), or the like. The scintillator layer 75 is set in position, shape, and size so that the entire p-type semiconductor region 5 is hidden when viewed from the direction perpendicular to the surface 3 a of the semiconductor substrate 3.

The moisture-resistant protective film 77 is formed of a PET sheet or an epoxy resin kneaded with TiO ₂ and functions as a light-shielding film. Although the moisture-resistant protective film 77 covers the side surface and the light incident surface of the scintillator layer 75, the moisture-resistant protective film 77 does not cover the light-emitting surface of the scintillator layer 75. It enters the photodiode array 1 without being performed.

  The manufacturing method of the radiation detector according to the above embodiment is not limited to connecting the wiring board 81 after cutting the workpiece 65 after forming the modified region 50. For example, the modified region 50 may be formed after a melt processing region is formed and cut in the semiconductor substrate 3 by laser processing. In other words, as shown in FIG. 15A, a melt processing region is formed in the semiconductor substrate 3 by laser processing for the workpiece 61 similar to that in FIG. And as shown in FIG.15 (b), the dicing tape 63 is expanded and the process target object 61 is cut | disconnected along a cutting plan line, and the process target object 61a as shown in FIG.15 (c) is obtained. In this case, the semiconductor substrate 3 may be cut with a blade in the same manner as described above.

  Subsequently, as shown in FIG. 16A, bump electrodes 31 and 33 are formed at predetermined positions of the workpiece 61a by a solder paste screen printing method to obtain the workpiece 61b. Next, as illustrated in FIG. 16B, the bump electrodes 31 and 33 of the workpiece 61 b and the input portion 83 a of the wiring substrate 81 are connected. And as shown in FIG.16 (c), after attaching the dicing tape 63 to the output part 83b on the signal output surface 81b of the wiring board 81, the modified area | region 50 is formed by performing laser processing, The photodiode array 1a is connected to the wiring board 81. Further, the radiation detector can be obtained by forming the scintillator 73 and the bump electrode 85 after peeling the dicing tape 63 by UV irradiation.

.
1a to 1e, 91 ... photodiode array, 3 ... n-type (first conductivity type) semiconductor substrate, 3a, 3c ... front surface, 3b, 3d ... back surface, 5, 5a-5d ... p-type (second conductivity type) semiconductor Region, 11 ... pn junction, 13 ... photodiode, 33 ... bump electrode, 35 ... region (first region), 36 ... region (second region), 37, 37a to 37e ... region, 38 ... region, 50 , 50a, 50b, 52, 54, 56 ... reforming region, 56a ... first part, 56b ... second part, 73 ... scintillator, 100, 200, 300 ... radiation detector, F ... condensing point, La ... laser light, L1 ... light.

Claims (11)

A first conductivity type semiconductor substrate;
A plurality of second-conductivity-type semiconductor regions that are arranged side by side on the one side of the semiconductor substrate and each constitute a photodiode by bonding to the semiconductor substrate;
By irradiating the region between the adjacent second conductivity type semiconductor regions with a laser beam with a focusing point aligned with a predetermined position in the region, the arrangement direction of the adjacent second conductivity type semiconductor regions is increased. A modified region is formed extending in the intersecting direction,
The photodiode array, wherein the modified region is not formed in a region surrounded by at least three adjacent semiconductor regions of the second conductivity type. The plurality of second conductivity type semiconductor regions are two-dimensionally arranged in a matrix.
The modified region is formed only in a region between the second conductivity type semiconductor regions adjacent in the row direction and a region between the second conductivity type semiconductor regions adjacent in the column direction. The photodiode array according to claim 1. A first conductivity type semiconductor substrate;
A plurality of second-conductivity-type semiconductor regions that are arranged side by side on the one side of the semiconductor substrate and each constitute a photodiode by bonding to the semiconductor substrate;
By irradiating the region between the adjacent second conductivity type semiconductor regions with a laser beam with a focusing point aligned with a predetermined position in the region, the arrangement direction of the adjacent second conductivity type semiconductor regions is increased. A first modified region is formed extending in the intersecting direction,
In a region surrounded by at least three adjacent second-conductivity-type semiconductor regions, a second modified region is formed by irradiating a laser beam with a focusing point at a predetermined position in the region. And
The photodiode array, wherein the first modified region and the second modified region are located apart from each other. The plurality of second conductivity type semiconductor regions are two-dimensionally arranged in a matrix.
The first modified region is formed in a region between the second conductivity type semiconductor regions adjacent in the row direction and a region between the second conductivity type semiconductor regions adjacent in the column direction,
4. The photo according to claim 3, wherein the second modified region is formed in a region between the second conductivity type semiconductor regions adjacent to each other in a direction intersecting the row direction and the column direction. Diode array. A first conductivity type semiconductor substrate;
A plurality of second-conductivity-type semiconductor regions that are arranged side by side on the one side of the semiconductor substrate and each constitute a photodiode by bonding to the semiconductor substrate;
The semiconductor regions of the second conductivity type are two-dimensionally arranged in a matrix form,
Among the plurality of second-conductivity-type semiconductor regions, four adjacent second-conductivity-type semiconductor regions are separated from the first and second second-conductivity-type semiconductor regions adjacent in the row direction and in the column direction. A third second conductivity type semiconductor region adjacent to the first second conductivity type semiconductor region, and adjacent to the first second conductivity type semiconductor region in a direction crossing the row direction and the column direction. When the fourth second conductivity type semiconductor region is defined,
In a region between the first and second second-conductivity type semiconductor regions and the third and fourth second-conductivity type semiconductor regions, a laser beam is focused on a predetermined position of the region. By irradiating with light, a first modified region extending continuously in the row direction is formed,
The region between the first and second second-conductivity type semiconductor regions and the region between the third and fourth second-conductivity type semiconductor regions are condensed at predetermined positions in the respective regions. By irradiating the laser beam with the points aligned, a second modified region extending in the column direction is formed,
The photodiode array, wherein the first modified region and the second modified region are located apart from each other. The semiconductor substrate includes: a first region where the plurality of second conductivity type semiconductor regions are disposed; and a second region surrounding the first region and having an outer edge forming the outer edge of the semiconductor substrate. Have
The photodiode array according to claim 1, wherein a modified region is not formed in the second region. The semiconductor substrate includes: a first region where the plurality of second conductivity type semiconductor regions are disposed; and a second region surrounding the first region and having an outer edge forming the outer edge of the semiconductor substrate. Have
The modified region is formed in the second region by irradiating a laser beam with a focusing point at a predetermined position of the region. The photodiode array described in 1. A plurality of the modified regions of the second region are formed extending in a direction along the outer edge of the semiconductor substrate;
8. The photodiode array according to claim 7, wherein the plurality of modified regions surround the first region. The modified region of the second region includes a plurality of first portions extending in a direction along the outer edge of the semiconductor substrate and arranged apart from each other, and a region between the adjacent first portions, A plurality of second portions extending in a direction intersecting the outer edge of the semiconductor substrate and arranged apart from the first portion;
8. The photodiode array according to claim 7, wherein the plurality of first and second portions surround the first region.   10. The photodiode array according to claim 1, wherein bumps are arranged on a region surrounded by at least three adjacent semiconductor regions of the second conductivity type. The photodiode array according to any one of claims 1 to 10,
A radiation detector, comprising: a scintillator disposed on the one surface of the semiconductor substrate or on the other surface facing the one surface.

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