JP6076601B2 - Laser processing method, semiconductor device manufacturing method, and laser processing apparatus - Google Patents

Laser processing method, semiconductor device manufacturing method, and laser processing apparatus Download PDF

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JP6076601B2
JP6076601B2 JP2012016807A JP2012016807A JP6076601B2 JP 6076601 B2 JP6076601 B2 JP 6076601B2 JP 2012016807 A JP2012016807 A JP 2012016807A JP 2012016807 A JP2012016807 A JP 2012016807A JP 6076601 B2 JP6076601 B2 JP 6076601B2
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semiconductor substrate
laser
output value
region
gettering region
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JP2013157454A (en
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剛志 坂本
剛志 坂本
いく 佐野
いく 佐野
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浜松ホトニクス株式会社
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  The present invention relates to a laser processing method, a semiconductor device manufacturing method, and a laser processing apparatus.
  Conventionally, in a semiconductor device manufacturing process, a semiconductor substrate is irradiated with laser light to modify the inside of the semiconductor substrate, thereby forming a gettering region inside the semiconductor substrate for capturing impurities such as heavy metals. Is known (see, for example, Patent Documents 1 to 3).
JP 2009-272440 A JP 2003-264194 A JP 58-44726 A
  Incidentally, in recent years, the thinning of semiconductor devices has progressed, such as the emergence of ultrathin memories having a thickness of 50 μm or less. For example, in order to improve the reliability of such a semiconductor device, it is important to form a gettering region inside the semiconductor substrate. On the other hand, the output value of laser light for forming the gettering region is generally very small. For this reason, the formation state of the gettering region may not be stable as a result of being influenced by the state of the semiconductor substrate and other various conditions.
  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a laser processing method, a semiconductor device manufacturing method, and a laser processing apparatus capable of stably forming a gettering region.
  In order to solve the above-described problems, a laser processing method according to the present invention provides a gettering region for capturing impurities by irradiating a semiconductor substrate with laser light to modify the inside of the semiconductor substrate. This is a laser processing method formed inside, and after irradiating a predetermined portion of a semiconductor substrate with a laser beam whose output value is adjusted, image information indicating the formation state of a gettering region in the predetermined portion is acquired, and the image information is Based on the preparatory step for determining the first output value of the laser light for setting the amount of formation of the gettering region to a predetermined value or more, and the laser light adjusted to the first output value determined in the preparatory step is applied to the semiconductor substrate. And an execution step of forming a gettering region in the semiconductor substrate by irradiation.
  This laser processing method includes a laser processing implementation step for forming a gettering region inside a semiconductor substrate, and a preparation step that is a pre-step of the implementation step. In the preparation step, the semiconductor substrate is irradiated with laser light whose output value has been adjusted, and image information indicating the formation state of the gettering region in the irradiated portion is acquired. Then, based on the acquired image information, a first output value of the laser beam for making the amount of formation of the gettering region equal to or larger than a predetermined value is determined. For this reason, according to this laser processing method, it is possible to determine the output value of the laser beam capable of sufficiently forming the gettering region. Therefore, according to this laser processing method, the gettering region is stably formed inside the semiconductor substrate by irradiating the semiconductor substrate with the laser beam having the first output value determined in the preparation step in the implementation step. It becomes possible.
  In the laser processing method according to the present invention, the preparation step includes a first step of irradiating the predetermined portion with the laser beam whose output value is adjusted, and a second step of acquiring image information of the predetermined portion after the first step. And a third step of determining whether or not the amount of gettering regions formed in the predetermined portion is greater than or equal to a predetermined amount based on the image information after the second step. While gradually increasing the output value from the second output value, the first step, the second step, and the third step are sequentially performed until it is determined in the third step that the amount of formation of the gettering region is greater than or equal to a predetermined amount. By repeating, the first output value can be determined. In this case, since the first output value is determined by repeating the first to third steps while increasing the output value of the laser beam stepwise from the second output value, the laser beam having an output value larger than necessary is applied to the semiconductor substrate. Can be avoided.
  At this time, in the laser processing method according to the present invention, the second output value can be set to an output value such that a gettering region is not formed by laser light irradiation. In this case, since the output value of the laser beam is increased stepwise from the extent that the gettering region is not formed, the output of the laser beam that is necessary and sufficient to stably form the gettering region. The value can be determined reliably.
  In the laser processing method according to the present invention, the semiconductor substrate includes a used portion where a functional element is formed on a surface and an unused portion where a functional element is not formed, and the predetermined portion is an unused portion. Can do. In this case, since the preparation process is performed in the unused portion of the semiconductor substrate where the gettering region is formed in the implementation process, it is possible to determine the first output value in accordance with the actual processing conditions in the implementation process. It becomes.
  In the laser processing method according to the present invention, the amount of gettering regions formed can be the ratio of the number of gettering regions formed to the number of shots of laser light.
  Here, the semiconductor device manufacturing method according to the present invention includes a step of forming a gettering region in a semiconductor substrate and a plurality of functional elements on the surface of the semiconductor substrate by performing the laser processing method described above. And after forming the gettering region and after forming the functional element, the semiconductor substrate is cut for each functional element along a scheduled cutting line set to pass between adjacent functional elements. And a step of obtaining a plurality of semiconductor devices including one functional element.
  This semiconductor device manufacturing method implements the laser processing method described above. Therefore, according to this method for manufacturing a semiconductor device, it is possible to stably form a gettering region inside the semiconductor substrate, and as a result, it is possible to improve the reliability of the semiconductor device.
  The laser processing apparatus according to the present invention also forms a gettering region for trapping impurities inside the semiconductor substrate by irradiating the semiconductor substrate with laser light to modify the inside of the semiconductor substrate. An apparatus, a laser light source that emits laser light, an adjustment unit that adjusts an output value of the laser light, and an image of a predetermined portion of the semiconductor substrate irradiated with the laser light, thereby obtaining a gettering region in the predetermined portion. Acquisition means for acquiring image information indicating a formation state, and determination means for determining a first output value of a laser beam for making the amount of formation of the gettering region a predetermined amount or more based on the image information. Features.
  In this laser processing apparatus, the output value of the laser light from the laser light source is adjusted, and image information indicating the formation state of the gettering region in the portion irradiated with the laser light whose output value is adjusted is acquired. Then, based on the acquired image information, a first output value of the laser beam for making the amount of formation of the gettering region equal to or larger than a predetermined value is determined. For this reason, according to this laser processing apparatus, it becomes possible to determine the output value of the laser beam capable of sufficiently forming the gettering region. Therefore, according to this laser processing apparatus, the gettering region can be stably formed inside the semiconductor substrate by irradiating the semiconductor substrate with the laser light adjusted to the first output value determined as described above. It becomes possible.
  The laser processing apparatus according to the present invention further includes a determination unit that determines whether or not the amount of gettering regions formed in the predetermined portion is greater than or equal to a predetermined amount based on the image information, and the determination unit outputs the laser light. Adjusting the output value of the laser beam by the adjustment unit until the determination unit determines that the formation amount of the gettering region is greater than or equal to a predetermined value while gradually increasing the value from the second output value held in advance. The first output value can be determined by sequentially repeating the acquisition of the image information by the acquisition unit and the determination by the determination unit. In this case, it is possible to avoid irradiating the semiconductor substrate with laser light having an output value more than necessary.
  In the laser processing apparatus according to the present invention, the second output value can be set to an output value such that a gettering region is not formed by laser light irradiation. In this case, it is possible to reliably determine the output value of the laser beam necessary and sufficient for stably forming the gettering region.
  In the laser processing apparatus according to the present invention, the amount of gettering regions formed can be the ratio of the number of gettering regions formed to the number of shots of laser light.
  According to the present invention, it is possible to provide a laser processing method, a semiconductor device manufacturing method, and a laser processing apparatus capable of stably forming a gettering region.
It is a schematic block diagram of the laser processing apparatus used for formation of a modification area | region. It is a top view of the process target object used as the object of formation of a cutting | disconnection start area | region. It is sectional drawing along the III-III line of the workpiece of FIG. It is a top view of the processing target after laser processing. It is sectional drawing along the VV line of the workpiece of FIG. It is sectional drawing along the IV-IV line of the processing target object of FIG. It is sectional drawing of the semiconductor substrate in which formation of a gettering area | region is implemented. It is sectional drawing of the semiconductor substrate in which the gettering area | region was formed, and a semiconductor device. It is sectional drawing of the semiconductor substrate in which the gettering area | region was formed, and a semiconductor device. It is a top view which shows the formation aspect of a gettering area | region. It is a schematic block diagram of the laser processing apparatus used for the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. It is a top view of the semiconductor substrate with which the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention is enforced. It is a flowchart which shows the main processes of the laser processing method which concerns on one Embodiment of this invention. It is a figure which shows an example of the table | surface which the dimmer control part shown by FIG. 11 hold | maintains. It is a figure which shows an example of the image information which the IR camera shown by FIG. 11 acquired. It is an enlarged plan view of the unused part of the semiconductor substrate in which the preparatory process of the laser processing method which concerns on one Embodiment of this invention was implemented. It is the top view and sectional drawing of a semiconductor substrate with which the laser processing method concerning one embodiment of the present invention is carried out. It is the top view and sectional drawing of a semiconductor substrate with which the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention is implemented. It is the top view and sectional drawing of a semiconductor substrate with which the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention is implemented. It is the top view and sectional drawing of a semiconductor substrate with which the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention is implemented. It is the top view and sectional drawing of a semiconductor substrate with which the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention is implemented. It is a top view of the semiconductor substrate with which the laser processing method concerning other embodiment of this invention is implemented. It is a top view of the semiconductor substrate with which the laser processing method concerning other embodiment of this invention is implemented.
  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.
  In the semiconductor device manufacturing method according to the present embodiment, the semiconductor substrate is irradiated with laser light to modify the inside of the semiconductor substrate, thereby generating a crack in the thickness direction of the semiconductor substrate along the planned cutting line. There is a case where a cutting starting region (that is, a modified region functioning as a cutting starting region) for forming is formed inside the semiconductor substrate. Therefore, the formation of the cutting start region for the plate-like workpiece is not limited to the semiconductor substrate, and will be described with reference to FIGS.
  As shown in FIG. 1, a laser processing apparatus 100 includes a laser light source 101 that oscillates a laser beam L, a dichroic mirror 103 that is arranged to change the direction of the optical axis (optical path) of the laser beam L by 90 °, and And a condensing lens 105 for condensing the laser light L. Further, the laser processing apparatus 100 includes a support base 107 for supporting the workpiece 1 irradiated with the laser light L condensed by the condensing lens 105, and a stage 111 for moving the support base 107. In addition, a laser light source control unit 102 that controls the laser light source 101 and a stage control unit 115 that controls driving of the stage 111 are provided to adjust the output, pulse width, and the like of the laser light L.
  In this laser processing apparatus 100, the laser light L emitted from the laser light source 101 is changed in direction of the optical axis by 90 ° by the dichroic mirror 103, and the processing object 1 placed on the support base 107 is changed. The light is condensed inside by the condensing lens 105. At the same time, the stage 111 is moved, and the workpiece 1 is moved relative to the laser beam L along the planned cutting line 5. As a result, a modified region along the planned cutting line 5 is formed on the workpiece 1.
  As the workpiece 1, plate-like members (for example, substrates, wafers, etc.) made of various materials (for example, glass, semiconductor material, piezoelectric material, etc.) are used. As shown in FIG. 2, a scheduled cutting line 5 for cutting the workpiece 1 is set in the workpiece 1. The planned cutting line 5 is a virtual line extending linearly. When the modified region is formed inside the workpiece 1, as shown in FIG. 3, the laser beam L is directed along the planned cutting line 5 in a state where the focusing point P is aligned with the inside of the workpiece 1. (Ie, in the direction of arrow A in FIG. 2). As a result, as shown in FIGS. 4 to 6, the modified region 7 that functions as the cutting start region 8 is formed inside the workpiece 1 along the planned cutting line 5.
  In addition, the condensing point P is a location where the laser light L is condensed. Further, the planned cutting line 5 is not limited to a straight line, but may be a curved line, or may be a line actually drawn on the surface 3 of the workpiece 1 without being limited to a virtual line. In addition, the modified region 7 may be formed continuously or intermittently. Further, the modified region 7 may be in the form of a line or a dot. In short, the modified region 7 only needs to be formed at least inside the workpiece 1. In addition, a crack may be formed starting from the modified region 7, and the crack and modified region 7 may be exposed on the outer surface (front surface, back surface, or outer peripheral surface) of the workpiece 1.
  Incidentally, the laser light L here passes through the workpiece 1 and is particularly absorbed near the condensing point inside the workpiece 1, thereby forming the modified region 7 in the workpiece 1. (Ie, internal absorption laser processing). Therefore, since the laser beam L is hardly absorbed by the surface 3 of the workpiece 1, the surface 3 of the workpiece 1 is not melted. In general, when a removed portion such as a hole or a groove is formed by being melted and removed from the front surface 3 (surface absorption laser processing), the processing region gradually proceeds from the front surface 3 side to the back surface side.
  By the way, the modified region refers to a region in which density, refractive index, mechanical strength, and other physical characteristics are different from the surroundings. Examples of the modified region include a melt treatment region, a crack region, a dielectric breakdown region, a refractive index change region, and the like, and there is a region where these are mixed. Furthermore, as the modified region, there are a region where the density of the modified region in the material of the workpiece is changed compared to the density of the non-modified region, and a region where lattice defects are formed. Also known as the metastatic region).
In addition, the area where the density of the melt-processed area, the refractive index changing area, the modified area is changed compared to the density of the non-modified area, or the area where lattice defects are formed is In some cases, cracks (cracks, microcracks, etc.) are included in the interface between the non-modified region and the non-modified region. The included crack may be formed over the entire surface of the modified region, or may be formed in only a part or a plurality of parts. Examples of the processing object 1 include a substrate or wafer made of silicon, glass, LiTaO 2 or sapphire (Al 2 O 2 ), or a material including such a substrate or wafer.
  The modified region 7 is a region in which a plurality of modified spots (processing marks) are formed along the planned cutting line 5. The modified spot is a modified portion formed by one pulse shot of pulsed laser light (that is, one pulse of laser irradiation: laser shot). Examples of the modified spot include a crack spot, a melting treatment spot, a refractive index change spot, or a mixture of at least two of these. Considering the required cutting accuracy, required flatness of the cut surface, thickness of the workpiece, type, crystal orientation, etc., the size of the modified spot and the length of the crack to be generated are appropriately determined. It is preferable to control.
  Here, in the method of manufacturing a semiconductor device according to the present embodiment, a gettering region (that is, gettering) for capturing impurities by irradiating the semiconductor substrate with laser light to modify the inside of the semiconductor substrate. A modified region functioning as a region) is formed inside the semiconductor substrate. Therefore, formation of the gettering region for the semiconductor substrate will be described with reference to FIGS.
  As shown in FIG. 7, a semiconductor substrate 2 such as a silicon wafer is prepared. The semiconductor substrate 2 has a front surface 2a for forming a plurality of functional elements 25 and a back surface 2b opposite to the front surface 2a. The functional element 25 means, for example, a light receiving element such as a photodiode, a light emitting element such as a laser diode, a memory element such as a semiconductor memory, or a circuit element formed as a circuit.
  Subsequently, the surface 2a of the semiconductor substrate 2 is used as the laser beam incident surface, and the semiconductor substrate 2 is irradiated with the laser beam L with the focusing point P aligned with the interior of the semiconductor substrate 2, thereby forming the modified region 17 functioning as the gettering region 18 in the semiconductor. It is formed inside the substrate 2. More specifically, in the thickness direction of the semiconductor substrate 2, the semiconductor substrate is opposed to the formation region 25 a of each functional element 25 (region in which each functional element 25 is formed on the surface 2 a of the semiconductor substrate 2). A gettering region 18 is formed inside 2. In forming the gettering region 18, the back surface 2b of the semiconductor substrate 2 may be a laser light incident surface. Further, the gettering region 18 may be formed continuously or intermittently as long as it faces at least the respective formation regions 25a.
  Subsequently, a plurality of functional elements 25 are formed on the surface 2a of the semiconductor substrate 2, and then the semiconductor substrate 2 is cut for each functional element 25 to obtain a plurality of semiconductor devices. The gettering region 18 may be formed after the functional element 25 is formed, or may be formed both before and after the functional element 25 is formed.
  The gettering region 18 formed as described above exhibits a gettering effect for collecting and capturing impurities such as heavy metals inside the semiconductor substrate 2. Thereby, it can suppress that the functional element 25 is adversely affected by impurities such as heavy metals. Here, the modified region 17 functioning as the gettering region 18 is a region in which density, refractive index, mechanical strength, and other physical characteristics are different from the surroundings, and is, for example, a melt processing region.
  When it is necessary to reduce the thickness of the semiconductor substrate 2 to a predetermined thickness, the semiconductor substrate 2 has a predetermined thickness after the functional element 25 is formed and before the semiconductor substrate 2 is cut. The back surface 2b of the substrate 2 is polished. At this time, as shown in FIG. 8A, if the gettering region 18 is formed on the surface 2a side of the semiconductor substrate 2 with respect to the surface 16 to be polished, as shown in FIG. In addition, the gettering region 18 remains in the semiconductor device 20. On the other hand, as shown in FIG. 9A, if the gettering region 18 is formed on the back surface 2b side of the semiconductor substrate 2 with respect to the polishing end planned surface 16, as shown in FIG. 9B. The gettering region 18 does not remain in the semiconductor device 20. Here, the polishing is a thinning process comprising one or a combination of mechanical polishing (cutting, grinding, dry polishing, etc.), chemical polishing (chemical etching, etc.), chemical mechanical polishing (CMP), and the like.
  Incidentally, when the gettering region 18 is formed, the above-described laser processing apparatus 100 can be used. However, the modified region 7 that functions as the cutting start region 8 needs to be easily cracked in the thickness direction of the semiconductor substrate 2, whereas the modified region 17 that functions as the gettering region 18 It is necessary that such cracks are difficult to occur. Therefore, it is necessary to make the irradiation condition of the laser beam L different between the case where the modified region 7 functioning as the cutting start region 8 is formed and the case where the modified region 17 functioning as the gettering region 18 is formed.
  For example, when the modified region 7 that functions as the cutting start region 8 is formed, the output of the laser light L is about 10 to 40 μJ, whereas when the modified region 17 that functions as the gettering region 18 is formed. The output of the laser beam L is about 0.2 to 3.0 μJ. As a result, in the modified region 17 that functions as the gettering region 18, the width of the modified spot in the thickness direction of the semiconductor substrate 2 is 1 to 10 μm (more preferably 4 to 6 μm). The modified region 17 composed of the modified spot having such a width hardly causes a crack in the thickness direction of the semiconductor substrate 2 and sufficiently exhibits the gettering effect. As described above, the output of the laser beam L when forming the modified region 17 that functions as the gettering region 18 is lower than the output of the laser beam L when forming the modified region 7 that functions as the cutting start region 8. It is preferable.
  Further, for example, in the case of forming the modified region 7 that functions as the cutting starting region 8, the modified spot distance (distance between the nearest modified spots) is about 3.75 to 7.5 μm, In the case where the modified region 17 that functions as the gettering region 18 is formed, the modified spot distance is about 5 to 20 μm. The modified region 17 composed of the modified spots having such modified spot distances makes it difficult to extend cracks between the nearest modified spots and sufficiently exhibits the gettering effect. As described above, the modified spot distance when the modified region 17 that functions as the gettering region 18 is formed is longer than the modified spot distance when the modified region 7 that functions as the cutting start region 8 is formed. preferable.
  It should be noted that the adjustment of the modified spot distance when the modified region 17 functioning as the gettering region 18 is formed can be performed as follows. For example, as shown in FIG. 10A, a plurality of modifications are made along the moving direction of the laser light L (the direction in which the focal point P of the laser light L is moved relative to the semiconductor substrate 2). When the spots 17a are arranged in a line, the pulse pitch of the laser beam L (relative to the laser beam L) is set so that the modified spot distance d is difficult to extend the crack and can sufficiently exhibit the gettering effect. (Moving speed / repetition frequency of laser light L) may be set.
  Further, as shown in FIG. 10B, one laser beam L is branched along the direction intersecting the moving direction of the laser beam L and condensed at a plurality of locations, and the modified spot 17a is formed at each location. When forming the laser beam, one laser beam L may be branched and condensed at a plurality of locations so as to have the above-described modified spot distance d. Further, as shown in FIG. 10C, when the plurality of modified spots 17a are arranged in a plurality of rows along the moving direction of the laser beam L, the above-described modified spot distance d is set. The distance between the reforming spots 17a across adjacent rows may be set. In these cases, in the moving direction of the laser light L, the distance between the adjacent modified spots 17a can be increased, so that it is difficult to extend the crack along the direction.
  Subsequently, a method for manufacturing a semiconductor device according to an embodiment of the present invention will be described. First, a laser processing apparatus used in this semiconductor device manufacturing method will be described. FIG. 11 is a diagram showing a laser processing apparatus used in the semiconductor device manufacturing method according to the present embodiment. As shown in FIG. 11, the laser processing apparatus 100A is similar to the laser processing apparatus 100 described above, and includes a laser light source 101, a laser light source control unit 102, a dichroic mirror 103, a condensing lens (processing objective lens) 105, A support base 107, a stage 111, and a stage control unit 115 are provided.
  The laser processing apparatus 100A includes a dimmer (adjusting unit) 104 for dimming the laser light L, and a dimmer control unit (determination) that controls the dimmer 104 based on image information and output value information described below. (Means, determination means) 114. The dimmer 104 is disposed between the dichroic mirror 103 and the condensing lens 105 on the optical axis of the laser light L. The dimmer 104 is an attenuator made of, for example, a half-wave plate or a polarizing plate. The dimmer 104 adjusts the degree of dimming of the laser light L, for example, by changing the angle of the half-wave plate with respect to the optical axis of the laser light L under the control of the dimmer control unit 114. (That is, the output value of the laser beam L is adjusted). As described above, in the laser processing apparatus 100A, by using the dimmer 104, the output value of the laser light L for forming the gettering region 18 can be reliably adjusted.
  The angle of the half-wave plate in the dimmer 104 can be changed, for example, by changing the number of pulses of the pulse motor drive signal for changing the angle of the half-wave plate. In the following, the number of pulses is referred to as “attenuator pulse number” and is used as a term indicating the degree of attenuation of the laser light L. In the present embodiment, it is assumed that as the number of dimmer pulses increases, the degree of attenuation of the laser light L decreases and the output value of the laser light L increases.
  The laser processing apparatus 100 </ b> A further includes an IR camera (acquisition means) 106 for imaging the semiconductor substrate 2 placed on the support base 107, and a camera control unit (decision means) 116 for controlling the IR camera 106. I have. The IR camera 106 is attached to the condensing lens 105, for example. Under the control of the camera control unit 116, the IR camera 106 images a predetermined portion of the semiconductor substrate 2 irradiated with the laser light L, and acquires image information indicating the formation state of the gettering region 18 in the predetermined portion. . The IR camera 106 transmits the acquired image information to the camera control unit 116. The camera control unit 116 transmits the image information from the IR camera 106 to the dimmer control unit 114.
  The laser processing apparatus 100A further includes a power meter 108 for measuring the output value of the laser light L. The power meter 108 receives the laser beam L from the condensing lens 105, measures the output value of the laser beam L, and acquires output value information indicating the measurement result. The power meter 108 transmits the acquired output value information to the dimmer control unit 114.
  The dimmer control unit 114 and the camera control unit 116 are mainly configured by a computer including a CPU, a ROM, a RAM, and the like, for example. The dimmer control unit 114 and the camera control unit 116 may be configured separately, or may be configured integrally with each other. Details of the control of the dimmer controller 114 and the camera controller 116 will be described later.
  Next, a semiconductor device manufacturing method using the above-described laser processing apparatus 100A will be described. In this semiconductor device manufacturing method, a semiconductor substrate 2 as shown in FIG. 12 is used. As shown in FIG. 12, the semiconductor substrate 2 has a front surface 2a for forming a plurality of functional elements 25 and a back surface 2b opposite to the front surface 2a. The semiconductor substrate 2 is placed on the support 107 of the laser processing apparatus 100A so that the surface 2a is on the condensing lens 105 side (see FIG. 11).
  The functional elements 25 are arranged on the surface 2 a of the semiconductor substrate 2 so as to be arranged in a matrix along a direction substantially parallel to and substantially perpendicular to an orientation flat (hereinafter referred to as “OF”) 19 of the semiconductor substrate 2. A formation region 25a is set. That is, the semiconductor substrate 2 includes a used portion 2d where the functional element 25 is formed on the surface 2a and an unused portion 2f where the functional element 25 is not formed. FIG. 12B is an enlarged view of the unused portion 2f. The semiconductor substrate 2 can be a silicon wafer having a diameter of 12 inches and a thickness of 775 μm, for example.
  In the semiconductor device manufacturing method according to the present embodiment, first, a laser processing method according to an embodiment of the present invention is performed. In the laser processing method, the gettering region 18 is formed inside the semiconductor substrate 2 by modifying the inside of the semiconductor substrate 2 by irradiating the semiconductor substrate 2 with the laser light L. FIG. 13 is a flowchart showing the main steps of such a laser processing method. As shown in FIG. 13, the laser processing method includes a preparation process and an execution process. In the preparation step, the laser light L whose output value is adjusted is irradiated to the unused portion 2f of the semiconductor substrate 2, and image information indicating the formation state of the gettering region 18 in the unused portion 2f is acquired, and the image information is obtained. Based on the above, the machining output value (first output value) of the laser beam L for determining the amount of formation of the gettering region 18 to a predetermined value or more is determined.
  For this purpose, first, the initial value of the dimmer pulse number of the dimmer 104 is determined (step S101). This step S101 will be described in more detail. In this step S101, first, the power meter 108 is irradiated with the laser beam L while changing the number of dimmer pulses of the dimmer 104 under the control of the dimmer controller 114, and the output value of the laser beam L Measure. Thereby, the number of dimmer pulses of the dimmer 104 and the measured value of the power meter 108 (that is, the output value of the laser light L) are associated with each other, and the dimmer control unit 114 in FIG. A table T1 as shown in FIG.
  The dimmer controller 114 can determine the initial value of the dimmer pulse number for adjusting the output value of the laser light L to the initial value (second output value) by referring to this table T1. it can. The initial value of the laser beam L is an output value such that the gettering region 18 is not formed by the irradiation of the laser beam L, and can be set to 0.03 W, for example. In that case, the initial value of the dimmer pulse number can be determined to be 190 by referring to the table T1. Note that the initial value of the laser beam L is held in advance by the dimmer controller 114.
  Here, the dimmer control unit 114 further holds a table T2 as shown in FIG. Table T2 is created in advance by a predetermined experiment, and the laser light L is applied to the semiconductor substrate 2 while changing the number of dimmer pulses of the dimmer 104 step by step (here, 10 steps to 6 steps). It is a table | surface which shows the determination result of the formation state of the gettering area | region 18 at the time of irradiation in three steps of A, B, and C. The determination results A to C are distinguished by the ratio of the number of gettering regions 18 (that is, the modified spots 17a) to the number of shots of the laser beam L. FIG. 15 shows an example of image information corresponding to each of the determination results A to C. In FIG. 15, SH indicates one shot of the laser beam L, and 17a indicates a modified spot formed by the one shot.
  In the state shown in FIG. 15A, the modified spot 17a is not formed at all. That is, in the state shown in FIG. 15A, the ratio of the number of modified spots 17a (0 here) to the number of shots SH (10 here) of the laser light L is 0%. In this case, the determination result is C. Note that the determination result is C, for example, when the ratio of the number of modified spots 17a to the number of shots SH of the laser light L is 0%.
  In the state shown in FIG. 15B, the modified spots 17a are sparsely formed. In the state shown in FIG. 15B, the ratio of the number of modified spots 17a (here, 5) to the number of shots SH (here, 10) of the laser light L is 50%. In this case, the determination result is B. The determination result is B, for example, when the ratio of the number of modified spots 17a to the number of shots SH of the laser beam L is greater than 0% and less than 100%.
  In the state shown in FIG. 15C, the modified spots 17a are formed for all the shots SH of the laser light L. That is, in the state shown in FIG. 15C, the ratio of the number of modified spots 17a (10 here) to the number of shots SH (10 here) of the laser light L is 100%. In this case, the determination result is A. The determination result can be A when, for example, the ratio of the number of modified spots 17a to the number of shots SH of the laser light L is 100%. By repeating such irradiation of the laser light L and determination of the formation state of the gettering region 18 a plurality of times (here, four times), a table T2 shown in FIG. 14B is obtained.
  In step S101, the dimmer control unit 114 can further determine the initial value of the dimmer pulse number of the dimmer 104 by further referring to the table T2. For example, according to Table T2, when the number of dimmer pulses is 200 (dimming degree 1: when the degree of dimming is the highest, that is, when the output value of the laser beam L is the smallest), N1 to N4 In all trials, the determination result is C. Therefore, if the initial value of the dimmer pulse number is set to be smaller than 200, the output value of the laser light L is adjusted to an output value at which the gettering region 18 is not sufficiently formed.
  Subsequently, in a state where the dimmer control unit 114 sets the number of dimmer pulses of the dimmer 104 to the initial value determined in step S102 (that is, in a state where the output value of the laser light L is adjusted to the initial value). ) Irradiate the unused portion 2f of the semiconductor substrate 2 with the laser beam L using the surface 2a of the semiconductor substrate 2 as the laser beam incident surface (step S102: first step). At this time, for example, the laser light L is irradiated along the first line L1 in the unused portion 2f (see FIG. 12B).
  Subsequently, under the control of the camera control unit 116, the unused portion 2f is imaged by the IR camera 106, and image information indicating the formation state of the gettering region 18 in the unused portion 2f is acquired (step S103: second). Process). The image information acquired at this time is transmitted from the IR camera 106 to the dimmer control unit 114 via the camera control unit 116.
  Subsequently, the dimmer controller 114 determines whether or not the formation amount of the gettering region 18 is greater than or equal to a predetermined amount in the unused portion 2f based on the image information acquired in step S103 (step S104: (3rd process). Here, the amount of gettering region 18 formed can be, for example, the ratio of the number of modified spots 17a to the number of shots SH of laser light L. That is, in this step S104, it can be determined whether or not the ratio of the number of modified spots 17a to the number of shots SH of the laser beam L is greater than or equal to a predetermined value. This determination can be performed in the same manner as when creating the table T2 described above. For example, when the ratio of the number of modified spots 17a to the number of shots SH is 100% or more (that is, for example, in the case of the determination result A described above), it can be determined that the number is greater than or equal to a predetermined value.
  Subsequently, when it is determined that the amount of formation of the gettering region 18 is not equal to or greater than a predetermined value as a result of the determination in step S104, the dimmer control unit 114 sets the dimmer pulse number of the dimmer 104 from the initial value. The level is increased (that is, the output value of the laser beam L is increased by one level) (step S105). At this time, the degree of increasing the number of dimmer pulses can be determined with reference to Table T2, for example. According to Table T2, when the number of dimmer pulses is changed from 200 to 210, trials with a determination result of B appear. Therefore, also in this case, the degree of increasing the number of dimmer pulses can be determined to be about 10.
  After increasing the number of dimmer pulses by one step in step S105, the process returns to step S102, and steps S102 to S104 are repeated. This repetition is performed until the number of gettering regions 18 formed is determined to be greater than or equal to a predetermined value in step S104 while the number of dimmer pulses is increased stepwise in step S105 (that is, for example, the determination result is A). Done).
  In other words, the dimmer control unit 114 and the camera control unit 116 increase the formation value of the gettering region 18 to a predetermined value or more while gradually increasing the output value of the laser light L from an initial value that is held in advance. Until the determination is made, the adjustment of the output value of the laser light L by the dimmer 104, the acquisition of image information by the IR camera 106, and the determination of the formation state of the gettering region 18 are repeated in order. In this repetition, the laser beam L is irradiated in order along each of the first line L1 to the sixth line L6 in the unused portion 2f, for example.
  FIG. 16 is an enlarged view showing an example of the unused portion 2f when Steps S102 to S105 are repeatedly performed. As shown in FIG. 16, in this example, in the first and second implementations (that is, the implementation when the number of dimmer pulses is the initial value and the attenuation corresponding to the dimming degree 2 in Table T2). In the implementation with the number of optical pulses, the gettering region 18 is not formed at all (see the first line L1 and the second line L2 in the figure). Accordingly, in the first and second implementation steps S104, it is determined that the amount of formation of the gettering region 18 is less than a predetermined amount (for example, the determination result is C).
  In the third and fourth trials (that is, in the case where the number of dimming pulses corresponding to the dimming degree 3 and the dimming degree 4 in Table T2 is used), the gettering regions 18 are sparsely formed. (See the third line L3 and the fourth line L4 in the figure). Therefore, in the third and fourth implementation steps S104, it is determined that the formation amount of the gettering region 18 is less than a predetermined amount (for example, the determination result is B).
  Further, in the fifth implementation (that is, in the implementation when the number of dimmer pulses corresponding to the dimming degree 5 in Table T2 is used), the gettering region 18 is sufficiently formed. Therefore, in step S105 in the fifth implementation, it is determined that the amount of formation of the gettering region 18 is greater than or equal to a predetermined amount (for example, the determination result is A). In Table T2, the result of the sixth trial (that is, the implementation when the number of dimmer pulses corresponding to the dimming degree 6 is used) is shown. In this example, the gettering region is obtained in the fifth implementation. Since 18 is sufficiently formed, the sixth implementation is not performed. Therefore, the number of dimmer pulses at the time of the fifth implementation can be determined as the threshold of the number of dimmer pulses for forming the gettering region 18.
  By repeating the steps S102 to S105 in this way, the threshold value of the number of light-attenuator pulses for forming the gettering region 18 by a predetermined amount or more (that is, necessary and sufficient for forming the gettering region 18) is determined. (That is, the threshold value of the output value of the laser beam L is determined). Then, the dimmer controller 114 determines the value of the number of dimmer pulses that is one step larger than the threshold value determined in this way, so that the processing output value of the laser beam for actually performing laser processing ( First output value) is determined (step S106). Here, the degree of increasing the number of light-attenuator pulses is, for example, about 10 with reference to Table T2 or from the viewpoint of performing a modification that hardly causes cracks in the thickness direction of the semiconductor substrate 2. It can be. In addition, various examples in the above preparation process (for example, the output value of the laser beam, the number of dimmer pulses, the formation state of the gettering region 18) are actual laser processing apparatuses (for example, manufactured by Hamamatsu Photonics Co., Ltd.) 400SS (product number: L9571-11)) is used.
  In this laser processing method, after the processing output value of the laser beam L is determined, the process proceeds from the preparation process to the execution process. In the implementation step, the gettering region 18 is formed inside the semiconductor substrate 2 by irradiating the semiconductor substrate 2 with the laser light L adjusted to the processing output value determined in step S106 (step S107). Details of step S107 will be described. In this step S107, as shown in FIG. 17, first, a formation planned line 15 for forming the gettering region 18 is set on the surface 2a of the semiconductor substrate 2. Here, the formation lines 15 are set in a lattice shape, and each of the columns of the formation regions 25a aligned in a direction substantially parallel to the OF 19 and the formation regions 25a aligned in a direction substantially perpendicular to the OF 19 are formed. Along the respective rows, the central portion of each forming region 25a is passed.
  Subsequently, the surface 2a of the semiconductor substrate 2 is used as the laser light incident surface, and the light collecting point P is set inside the semiconductor substrate 2 (here, the back surface 2b side of the semiconductor substrate 2 with respect to the polishing-finished planned surface 16). The semiconductor substrate 2 is irradiated with the laser light L under the irradiation conditions when the modified region 17 that functions as the ring region 18 is formed. Note that the output value of the laser beam L is adjusted to the processing output value determined in step S106. In the irradiation with the laser light L, the condensing point P of the laser light L is moved along each planned formation line 15 while the optical axis of the laser light L is positioned on each planned formation line 15. As a result, a gettering region 18 is formed inside the semiconductor substrate 2.
  However, when the optical axis of the laser light L passes through a portion where the formation scheduled line 15 and the planned cutting line 5 intersect, the irradiation of the laser light L is turned off, and each formation region 25a is set to the optical axis of the laser light L. When the laser beam passes, the laser beam L is turned on. Therefore, in this step S107, the gettering region 18 is formed so as not to intersect the planned cutting line 5 when viewed from the thickness direction of the semiconductor substrate 2. Further, in this step S107, the gettering region 18 is formed on the back surface 2b side of the semiconductor substrate 2 with respect to the planned polishing end surface 16. Note that the scheduled cutting lines 5 are set in a lattice shape in a subsequent process so as to pass between the functional elements 25 adjacent to each other (that is, between the formation regions 25a adjacent to each other).
  In order to move the condensing point P of the laser light L relative to the semiconductor substrate 2, the support 107 may be moved, or the laser light source 101 side (the laser light source 101, the dichroic mirror 103, the reduction amount). The optical device 104, the condensing lens 105, etc.) may be moved, or both the support 107 and the laser light source 101 side may be moved. Thus, the laser processing method for forming the gettering region 18 is completed.
  In the semiconductor device manufacturing method according to the present embodiment, a process of forming the functional element 25 is performed following the above laser processing method. In this step, a plurality of functional elements 25 are formed on the surface 2a of the semiconductor substrate 2 as shown in FIG. The functional element 25 is formed in each of the formation regions 25a. At this time, the gettering region 18 formed in a cross shape along the formation line 15 is opposed to the formation region 25 a of the functional element 25 in the thickness direction of the semiconductor substrate 2.
  In the method for manufacturing a semiconductor device according to this embodiment, a step of cutting the semiconductor substrate 2 is performed following the step of forming the functional element 25. In this step, the semiconductor substrate 2 is cut for each functional element 25 along the scheduled cutting line 5 set so as to pass between adjacent functional elements 25, and a plurality of semiconductor devices 20 including one functional element 25 are formed. obtain. Details of this step will be described.
  In this step, first, as shown in FIG. 19, the cutting starting point region 8 is formed inside the semiconductor substrate 2 using the laser processing apparatus 100 </ b> A as follows. That is, after the protective film 22 is attached to the front surface 2a of the semiconductor substrate 2 so as to cover all the functional elements 25, the support base 107 of the laser processing apparatus 100A so that the back surface 2b of the semiconductor substrate 2 becomes the laser light incident surface. The semiconductor substrate 2 is placed thereon, and the cutting lines 5 are set in a lattice shape so as to pass between the functional elements 25 adjacent to each other (that is, between the adjacent formation regions 25a).
  Then, the back surface 2b of the semiconductor substrate 2 is used as the laser light incident surface, and the condensing point P is aligned with the inside of the semiconductor substrate 2 (here, the back surface 2b side of the semiconductor substrate 2 with respect to the gettering region 18). The semiconductor substrate 2 is irradiated with the laser beam L under the irradiation condition of the laser beam when the modified region 7 functioning as 8 is formed. The output value of the laser beam L is adjusted to a value necessary for forming the modified region 7 that functions as the cutting start region 8. When the laser beam L is irradiated, the condensing point P of the laser beam L is moved along each planned cutting line 5 while the optical axis of the laser beam L is positioned on each planned cutting line 5.
  As described above, in this cutting step, the semiconductor substrate 2 is irradiated with the laser light L to modify the inside of the semiconductor substrate 2, so that the cutting origin region is formed inside the semiconductor substrate 2 along the planned cutting line 5. 8 is formed. Then, by irradiating the semiconductor substrate 2 with the laser beam L, the crack 21 generated from the cutting start region 8 is caused to reach the surface 2 a of the semiconductor substrate 2. Here, since the condensing point P is set on the back surface 2b side of the semiconductor substrate 2 with respect to the gettering region 18, the cutting starting point region 8 is also formed on the back surface 2b side of the semiconductor substrate 2 with respect to the gettering region 18. The In order to move the condensing point P of the laser beam L relative to the semiconductor substrate 2, the support 107 may be moved, the laser light source 101 side may be moved, or You may move both the support stand 107 and the laser light source 101 side.
  Subsequently, as shown in FIG. 20, the semiconductor substrate 2 to which the protective film 22 is attached is placed on the support base 207 of the polishing apparatus, and the back surface 2 b of the semiconductor substrate 2 reaches the planned polishing end surface 16. The back surface 2b of the semiconductor substrate 2 is polished until the process is completed (that is, the gettering region 18 does not remain). As a result, the polishing surface reaches the crack 21 generated from the cutting start region 8 and extending toward the back surface 2 b of the semiconductor substrate 2, and the semiconductor substrate 2 is cut along the planned cutting line 5. The thickness of the semiconductor substrate 2 after polishing is, for example, about 50 μm.
  Subsequently, as shown in FIG. 21, an expanded film 23 is attached to the back surface 2 b of the semiconductor substrate 2, and then the protective film 22 is removed from the front surface 2 a of the semiconductor substrate 2. Then, in order to pick up a plurality of semiconductor devices 20 obtained by cutting the semiconductor substrate 2, the expanded film 23 is expanded radially outward to separate the plurality of semiconductor devices 20 from each other. A plurality of semiconductor devices 20 including the functional element 25 are obtained as described above.
  As described above, the semiconductor device manufacturing method according to the present embodiment is a laser that forms the gettering region 18 inside the semiconductor substrate 2 before the functional element formation step of forming the functional element 25 on the semiconductor substrate 2. Implement the processing method. The laser processing method includes a laser processing implementation process for forming the gettering region 18 and a preparation process that is a pre-process of the implementation process. In the preparation step, after the laser beam L whose output value has been adjusted is irradiated onto the unused portion 2f of the semiconductor substrate 2, image information indicating the formation state of the gettering region 18 in the unused portion 2f is acquired. Then, based on the acquired image information, a processing output value of laser light for determining the amount of formation of the gettering region 18 to a predetermined value or more is determined.
  Therefore, according to the laser processing method and the laser processing apparatus 100A that performs the laser processing method, it is possible to determine the output value of the laser light L that can sufficiently form the gettering region 18. In this laser processing method, the gettering region 18 is stably formed inside the semiconductor substrate 2 by irradiating the semiconductor substrate 2 with the laser light L having the processing output value determined in the preparation step in the implementation process. It becomes possible to form.
  In this laser processing method, steps S102 to S104 are repeated until it is determined that the amount of gettering region 18 formed is greater than or equal to a predetermined value while gradually increasing the output value of laser light L. Thus, the processing output value of the laser beam L is determined. For this reason, according to the laser processing method and the laser processing apparatus 100A that performs the laser processing method, it is possible to avoid irradiating the semiconductor substrate 2 with the laser light L having an output value more than necessary.
  Further, in this laser processing method, the initial value of the output value of the laser beam is set to an output value that prevents the gettering region from being formed by the laser beam irradiation. For this reason, according to the laser processing method and the laser processing apparatus 100A that performs the laser processing method, the output value of the laser light L is set to a value sufficient for stably forming the gettering region 18. The output value can be reliably determined.
  Further, in this laser processing method, prior to the formation of the gettering region 18, the power meter 108 is irradiated with the laser light L while changing the number of dimmer pulses of the dimmer 104, and the output of the laser light L is obtained. By measuring the value, the number of dimmer pulses of the dimmer 104 is associated with the measured value of the power meter 108 (that is, the output value of the laser light L). For this reason, according to this laser processing method and the laser processing apparatus 100A that performs the laser processing method, the laser beam L is reliably irradiated with a desired output value when the gettering region 18 is formed. Is possible.
  Thus, according to the method for manufacturing a semiconductor device according to this embodiment, the reliability of the semiconductor device 20 is improved by forming the gettering region 18 stably in the semiconductor substrate 2 by the laser processing method. It becomes possible to do.
  The above embodiments describe one embodiment of the laser processing method, the semiconductor device manufacturing method, and the laser processing apparatus according to the present invention. Therefore, the laser processing method, the semiconductor device manufacturing method, and the laser processing apparatus according to the present invention are not limited to the above-described embodiments. The laser processing method, the semiconductor device manufacturing method, and the laser processing apparatus according to the present invention may be modified from the above-described aspects without departing from the spirit of each claim described in the claims. .
  For example, when the semiconductor substrate 2 is cut along the planned cutting line 5, a stacked portion such as an oxide film may be formed on the surface 2 a of the semiconductor substrate 2 so as to extend between the adjacent functional elements 25. In that case, the laminated portion may be cut along with the semiconductor substrate 2 along the planned cutting line 5.
  In the above embodiment, before polishing the back surface 2b of the semiconductor substrate 2, the semiconductor substrate 2 is not completely cut along the scheduled cutting line 5, and after polishing the back surface 2b of the semiconductor substrate 2, Although the semiconductor substrate 2 has been completely cut along the planned cutting line 5, it is not limited to this. That is, the semiconductor substrate 2 may be completely cut along the scheduled cutting line 5 before the back surface 2b of the semiconductor substrate 2 is polished. Even in this case, if the semiconductor substrate 2 is cut by extending the crack 21 generated from the modified region 7 that functions as the cutting start region 8, the cut surfaces of the semiconductor substrate 2 cut by the crack 21 are in close contact with each other. It becomes a state. Therefore, the semiconductor substrate 2 can be thinned while suppressing occurrence of chipping and cracking of the semiconductor substrate 2 due to polishing.
  Further, the modified region 17 functioning as the gettering region 18 and the modified region 7 functioning as the cutting start region 8 are not limited to the case where they are formed only due to multiphoton absorption, and correspond to multiphoton absorption. It may be formed due to other light absorption such as light absorption or thermal influence. That is, multiphoton absorption is an example of a phenomenon that can form a modified region.
  Further, the modified region 17 functioning as the gettering region 18 may have various shapes depending on the formation pattern of the functional element 25 as long as the modified region 17 faces the formation region 25 a of the functional element 25 in the thickness direction of the semiconductor substrate 2. Can be taken.
  As an example, as shown in FIG. 22, the gettering regions 18 may be formed in a plurality of rows vertically and horizontally with respect to one forming region 25a. Further, as shown in FIG. 23A, the laser beam L1 is moved in the radial direction of the semiconductor substrate 2 while rotating the semiconductor substrate 2, so that one formation region is formed as shown in FIG. The curved gettering region 18 may be formed in at least one row with respect to 25a. Thus, when the formation line 15 for forming the gettering region 18 is spiral with respect to the semiconductor substrate 2, the modified spot distance (distance between the nearest modified spots) is substantially constant. It is desirable to change the rotational speed of the semiconductor substrate 2 and the repetition frequency of the laser light L so that And in any case shown in FIG.22 and FIG.23, by performing ON / OFF control of the laser beam L, when it sees from the thickness direction of the semiconductor substrate 2, it does not cross | intersect the scheduled cutting line 5. A gettering region 18 can be formed inside the semiconductor substrate 2.
  Further, when the gettering region 18 is formed, it is not necessary to perform ON / OFF control of the laser light L. In that case, in a state where the laser light L is always ON, the condensing point of the laser light L along each formation line 15 while the optical axis of the laser light L is positioned on each formation line 15. Move P. By forming the gettering region 18 by irradiating the laser beam L in this way, the gettering region 18 and the planned cutting line 5 intersect when viewed from the thickness direction of the semiconductor substrate 2.
  Further, the modified regions 7 functioning as the cutting start region 8 may be formed in a plurality of rows so as to be aligned in the thickness direction of the semiconductor substrate 2 with respect to one cutting scheduled line 5. Further, the cutting start region 8 is not limited to the case where it is formed on the back surface 2b side of the semiconductor substrate 2 with respect to the gettering region 18, but is formed on the surface 2a side of the semiconductor substrate 2 with respect to the gettering region 18. Also good.
  In the above-described embodiment, the semiconductor substrate 2 is cut by extending the crack 21 generated from the modified region 7 that functions as the cutting start region 8. However, the cutting line 5 is cut by other methods such as cutting with a blade. The semiconductor substrate 2 may be cut along. Also in this case, since the influence of the gettering region 18 on the portion along the planned cutting line 5 in the semiconductor substrate 2 is suppressed, the semiconductor substrate 2 can be cut along the planned cutting line 5 with high accuracy. it can.
  In the above embodiment, the back surface 2b of the semiconductor substrate 2 is polished so that the gettering region 18 does not remain. However, as shown in FIG. 8, the back surface 2b of the semiconductor substrate 2 is formed so that the gettering region 18 remains. You may grind | polish. In that case, in the semiconductor device 20, the gettering region 18 may be housed in the semiconductor substrate 2 or exposed on the back surface 2b.
  In the above embodiment, the dimmer 104 is used as the means for adjusting the output value of the laser light L in the laser processing apparatus 100A. However, the means for adjusting the output value of the laser light L is not limited to this. For example, in the laser processing apparatus 100A, the laser light source control unit 102 may directly adjust the output value of the laser light source 101.
  In the above embodiment, the image information indicating the formation state of the gettering region 18 in the unused portion 2f of the semiconductor substrate 2 is acquired using the IR camera 106. However, the information indicating the formation state of the gettering region 18 is an image. For example, information indicating the formation state of the gettering region 18 may be acquired using a photoluminescence measuring device or the like instead of the IR camera 106.
  Further, in the above embodiment, the step of forming the functional element 25 is performed after the laser processing method is performed and the gettering region 18 is formed. However, after the step of forming the functional element 25 is performed, the laser processing method is performed. The gettering region 18 may be formed by implementation.
  DESCRIPTION OF SYMBOLS 2 ... Semiconductor substrate, 2a ... Surface, 5 ... Planned cutting line, 18 ... Gettering area | region, 20 ... Semiconductor device, 25 ... Functional element, 2d ... Used part, 2f ... Unused part (predetermined part), 100A ... Laser processing Numerals 101, 101, laser light source, 104, dimmer (adjustment means), 106, IR camera (acquisition means), 114, dimmer control section (determination means, determination means), 116, camera control section (determination means) , L: Laser light.

Claims (11)

  1. A laser processing method for forming a gettering region for capturing impurities by irradiating a semiconductor substrate with laser light to modify the inside of the semiconductor substrate,
    After irradiating the predetermined portion of the semiconductor substrate with the laser beam whose output value is adjusted, image information indicating a formation state of the gettering region in the predetermined portion is acquired, and the gettering is performed based on the image information A preparatory step of determining a first output value of the laser beam for making the formation amount of the region a predetermined value or more;
    An implementation step of irradiating the semiconductor substrate with the laser light adjusted to the first output value determined in a preparation step to form the gettering region in the semiconductor substrate;
    With
    The amount of formation of the gettering region is a ratio of the number of gettering regions formed to the number of shots of the laser light.
  2. The preparation step includes
    A first step of irradiating the predetermined portion with the laser beam whose output value is adjusted;
    A second step of acquiring the image information of the predetermined portion after the first step;
    After the second step, based on the image information, a third step of determining whether the formation amount of the gettering region in the predetermined portion is greater than or equal to the predetermined amount,
    In the preparation step,
    While increasing the output value of the laser beam stepwise from the second output value, the first step, the first step until the formation amount of the gettering region is determined to be greater than or equal to the predetermined value in the third step. The laser processing method according to claim 1, wherein the first output value is determined by sequentially repeating two steps and the third step.
  3.   3. The laser processing method according to claim 2, wherein the second output value is an output value in which the gettering region is not formed by the irradiation of the laser light.
  4. The semiconductor substrate includes a use portion where a functional element is formed on a surface and a non-use portion where the functional element is not formed,
    The laser processing method according to claim 1, wherein the predetermined portion is the unused portion.
  5. Forming a gettering region for trapping impurities inside the semiconductor substrate by carrying out a laser processing method;
    Forming a plurality of functional elements on the surface of the semiconductor substrate after forming the gettering region;
    After forming the gettering region and after forming the functional element, the semiconductor substrate is cut for each functional element along a planned cutting line set to pass between the adjacent functional elements. And obtaining a plurality of semiconductor devices including one functional element;
    With
    The laser processing method is a laser processing method in which the gettering region is formed inside the semiconductor substrate by modifying the inside of the semiconductor substrate by irradiating the semiconductor substrate with laser light, and an output value After irradiating the predetermined portion of the semiconductor substrate with the laser beam adjusted to obtain image information indicating the formation state of the gettering region in the predetermined portion, and obtaining the image of the gettering region based on the image information A preparatory step for determining a first output value of the laser light for making the formation amount a predetermined value or more, and irradiating the semiconductor substrate with the laser light adjusted to the first output value determined in the preparatory step as in the step of forming the gettering region inside the semiconductor substrate, seen including,
    The amount of gettering region formed is a ratio of the number of gettering regions formed to the number of shots of the laser light.
    A method for manufacturing a semiconductor device.
  6. The preparation step includes
    A first step of irradiating the predetermined portion with the laser beam whose output value is adjusted;
    A second step of acquiring the image information of the predetermined portion after the first step;
    After the second step, based on the image information, a third step of determining whether the formation amount of the gettering region in the predetermined portion is greater than or equal to the predetermined amount,
    In the preparation step,
    While increasing the output value of the laser beam stepwise from the second output value, the first step, the first step until the formation amount of the gettering region is determined to be greater than or equal to the predetermined value in the third step. 6. The method of manufacturing a semiconductor device according to claim 5, wherein the first output value is determined by sequentially repeating two steps and the third step.
  7.   The method of manufacturing a semiconductor device according to claim 6, wherein the second output value is an output value in which the gettering region is not formed by the laser light irradiation.
  8. The semiconductor substrate includes a use portion where a functional element is formed on a surface and a non-use portion where the functional element is not formed,
    The method for manufacturing a semiconductor device according to claim 5, wherein the predetermined portion is the unused portion.
  9. A laser processing apparatus for forming a gettering region for trapping impurities inside the semiconductor substrate by irradiating the semiconductor substrate with laser light to modify the inside of the semiconductor substrate,
    A laser light source for emitting the laser light;
    Adjusting means for adjusting the output value of the laser beam;
    Acquisition means for acquiring image information indicating a formation state of the gettering region in the predetermined portion by imaging a predetermined portion irradiated with the laser light of the semiconductor substrate;
    Determining means for determining a first output value of the laser beam for making the amount of formation of the gettering region a predetermined amount or more based on the image information;
    With
    The amount of formation of the gettering region is a ratio of the number of gettering regions formed to the number of shots of the laser light.
  10. Based on the image information, further comprising determination means for determining whether the amount of formation of the gettering region in the predetermined portion is equal to or greater than the predetermined;
    The determination means increases the output value of the laser beam stepwise from a second output value held in advance until the determination means determines that the formation amount of the gettering region is equal to or greater than the predetermined value. The first output value is determined by sequentially repeating the adjustment of the output value of the laser beam by the adjustment unit, the acquisition of the image information by the acquisition unit, and the determination by the determination unit. The laser processing apparatus according to claim 9 .
  11. The laser processing apparatus according to claim 10 , wherein the second output value is an output value at which the gettering region is not formed by irradiation with the laser light.
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