JP2016096320A - Semiconductor chip manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor chip manufacturing method which makes it easy to balance inhibition of remaining adhesive layer on a surface of a semiconductor substrate and inhibition of breakage of a semiconductor chip stepped part.SOLUTION: A semiconductor chip manufacturing method comprises: a process of forming a surface side groove 400 by dry etching; a process of attaching a dicing tape having an adhesive layer 164 on a substrate surface; a process of forming from a rear face side of a substrate W, a rear face side groove 170 with a width wider than a width of the surface side groove 400, along the surface side groove 400 by a dicing blade; and a process of peeling the dicing tape after forming the rear face side groove 170. Formation of the surface side groove 400 is started at a first etching intensity where a width of the groove gradually decreases toward a depth direction, and on the way of forming the groove, the etching intensity is changed to a second etching intensity stronger than the first etching intensity, where the groove extends downward without an increase in width of the groove to form the groove having no part where the width increases.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a method for manufacturing a semiconductor piece.

  A first groove is formed with a first blade from the front surface side of the sapphire substrate, and then a second groove wider and deeper than the first groove is formed with a second blade from the back surface side. There has been proposed a dicing method capable of improving the yield without reducing the number of chips that can be obtained from the substrate (Patent Document 1). Also, there is a method of increasing the number of semiconductor elements that can be formed on a wafer by forming a groove with a laser from the wafer surface to the middle of the wafer and then cutting with a blade from the back surface of the wafer to the position where the laser groove is reached. It has been proposed (Patent Document 2).

JP 2003-124151 A JP 2009-88252 A

  An object of this invention is to provide the manufacturing method of the semiconductor piece which is easy to make compatible the suppression of the residual of the adhesion layer on the surface of a semiconductor substrate, and the damage suppression of the level | step-difference part of a semiconductor piece.

Claim 1 is a process of forming a groove on the front surface side by dry etching from the front surface to the back surface of the substrate, a step of attaching a holding member having an adhesive layer on the surface on which the groove on the front surface side is formed, A step of forming a groove on the back surface wider than the width of the groove on the front surface side from the back surface side of the substrate with the groove on the front surface side by a rotating cutting member, and after the formation of the groove on the back surface side Peeling off the surface and the holding member, and starting the formation of the groove on the surface side with a first etching strength at which the width of the groove on the surface side gradually decreases in the depth direction. During the formation of the groove on the surface side, the dry etching strength is higher than the first etching strength and has a second etching strength that extends downward without expanding the width of the inlet portion of the groove on the surface side. Switch the etching and point below the groove The method of manufacturing a semiconductor piece to form a groove in the surface side having no portion width increases.
According to a second aspect of the present invention, during the formation of the groove on the surface side, the flow rate of the protective film forming gas contained in the etching gas used for the dry etching is changed from the first flow rate to the protective film forming gas flow rate. 2. The method of manufacturing a semiconductor piece according to claim 1, wherein the groove on the surface side is formed by switching to a second flow rate lower than the first flow rate without stopping the flow rate.
According to a third aspect of the present invention, in the course of forming the groove on the surface side, the second gas flow rate of the etching gas contained in the etching gas used for the plasma etching is larger than the first flow rate from the first flow rate. The method of manufacturing a semiconductor piece according to claim 1, wherein the groove on the front surface side is formed by switching to a flow rate of 3 mm.
According to a fourth aspect of the present invention, the groove on the front surface side includes a first groove portion whose width gradually decreases from the front surface of the substrate toward the back surface, and a groove portion formed in communication with a lower portion of the first groove portion. And a second groove portion extending downward at a steeper angle than the angle of the first groove portion without expanding the width of the lowermost portion of the first groove portion. The manufacturing method of the semiconductor piece in any one of.
According to a fifth aspect of the present invention, in the semiconductor piece manufacturing method according to the fourth aspect, the side surface of the groove on the front surface side does not have a corner between the first groove portion and the second groove portion.

According to the first to third aspects, both the suppression of the adhesive layer remaining on the surface of the semiconductor substrate and the suppression of the breakage of the stepped portion of the semiconductor piece are achieved in comparison with the case where the groove on the surface side is formed under a single etching condition. Cheap.
According to claim 4, when the adhesive layer penetrates into the second groove portion, the semiconductor substrate is compared with the structure having the second groove portion having a width wider than the width of the lowermost portion of the first groove portion. It is possible to suppress the adhesive layer from remaining on the surface.
According to the fifth aspect, when the adhesive layer penetrates into the second groove portion, the surface of the semiconductor substrate is compared with the configuration having a corner portion between the first groove portion and the second groove portion. The remaining adhesive layer can be suppressed.

It is a flow which shows an example of the manufacturing process of the semiconductor piece which concerns on the Example of this invention. It is typical sectional drawing of the semiconductor substrate in the manufacturing process of the semiconductor piece which concerns on the Example of this invention. It is typical sectional drawing of the semiconductor substrate in the manufacturing process of the semiconductor piece which concerns on the Example of this invention. It is a schematic plan view of a semiconductor substrate (wafer) when circuit formation is completed. It is sectional drawing explaining the detail of the half dicing by a dicing blade. It is sectional drawing explaining the residual of the adhesion layer when peeling the tape for dicing from the substrate surface. 7A and 7B are cross-sectional views showing the shape of the first fine groove, and FIGS. 7C and 7D are the second fine groove according to the embodiment of the present invention. It is sectional drawing which shows the shape. 8A and 8B are cross-sectional views showing reverse tapered fine grooves, and FIGS. 8C and 8D are cross-sectional views showing vertical fine grooves. It is. FIG. 9A is a cross-sectional view showing a fine groove having only a forward taper shape, and FIGS. 9B and 9C are composed of a forward taper shape and a vertical shape. It is sectional drawing which shows the fine groove | channel. It is a schematic process sectional drawing explaining the manufacturing method of the fine groove | channel by the Example of this invention. FIG. 11A is a cross-sectional view showing a stepped portion formed in a semiconductor chip, FIG. 11B is a diagram illustrating a load applied to the stepped portion when cutting with a dicing blade, and FIG. It is a figure explaining breakage of a level difference part.

  The method of manufacturing a semiconductor piece according to the present invention is, for example, a method of manufacturing individual semiconductor pieces (semiconductor chips) by dividing (dividing into pieces) a substrate-like member such as a semiconductor wafer on which a plurality of semiconductor elements are formed. Applies to The semiconductor element formed on the substrate is not particularly limited, and can include a light emitting element, an active element, a passive element, and the like. In a preferred embodiment, the manufacturing method of the present invention is applied to a method of taking out a semiconductor piece including a light emitting element from a substrate, and the light emitting element can be, for example, a surface emitting semiconductor laser, a light emitting diode, or a light emitting thyristor. One semiconductor piece may include a single light-emitting element, or may include a plurality of light-emitting elements arranged in an array. A driving circuit for driving one or a plurality of light emitting elements can also be included. Further, the substrate can be, for example, a substrate made of silicon, SiC, a compound semiconductor, sapphire, or the like, but is not limited thereto, and is a substrate including at least a semiconductor (hereinafter collectively referred to as a semiconductor substrate). Any other material substrate may be used. In a preferred embodiment, it is a III-V group compound semiconductor substrate such as GaAs on which a light emitting element such as a surface emitting semiconductor laser or a light emitting diode is formed.

  In the following description, a method for forming a plurality of light emitting elements on a semiconductor substrate and taking out individual semiconductor pieces (semiconductor chips) from the semiconductor substrate will be described with reference to the drawings. It should be noted that the scale and shape of the drawings are emphasized for easy understanding of the features of the invention, and are not necessarily the same as the scale and shape of an actual device.

  FIG. 1 is a flowchart showing an example of a manufacturing process of a semiconductor piece according to an embodiment of the present invention. As shown in the figure, the method for manufacturing a semiconductor piece of this example includes a step of forming a light emitting element (S100), a step of forming a resist pattern (S102), and a step of forming fine grooves on the surface of a semiconductor substrate ( S104), a step of peeling the resist pattern (S106), a step of attaching a dicing tape to the surface of the semiconductor substrate (S108), a step of half dicing from the back surface of the semiconductor substrate (S110), and an ultraviolet (UV) on the dicing tape. ), A step of attaching an expanding tape to the back surface of the semiconductor substrate (S112), a step of peeling the dicing tape and irradiating the expanding tape with ultraviolet rays (S114), and picking a semiconductor piece (semiconductor chip) And a step (S116) of die mounting on a circuit board or the like. The cross-sectional views of the semiconductor substrate shown in FIGS. 2A to 2D and FIGS. 3E to 3I correspond to steps S100 to S116, respectively.

  In the step of forming light emitting elements (S100), as shown in FIG. 2A, a plurality of light emitting elements 100 are formed on the surface of a semiconductor substrate W such as GaAs. The light emitting element 100 is, for example, a surface emitting semiconductor laser, a light emitting diode, a light emitting thyristor, or the like. Note that although one region is shown as the light emitting element 100 in the drawing, one light emitting element 100 illustrates an element included in one separated semiconductor piece, and one light emitting element 100 is illustrated. It should be noted that the region may include not only one light emitting element but also a plurality of light emitting elements and other circuit elements.

  FIG. 4 is a plan view illustrating an example of the semiconductor substrate W when the light emitting element formation process is completed. In the drawing, for the sake of convenience, only the light emitting element 100 at the center portion is illustrated. On the surface of the semiconductor substrate W, a plurality of light emitting elements 100 are formed in an array in the matrix direction. The planar area of one light emitting element 100 is generally rectangular, and each light emitting element 100 is separated in a grid by a cutting area 120 defined by a scribe line or the like having a constant interval S.

  When the formation of the light emitting element is completed, a resist pattern is then formed on the surface of the semiconductor substrate W (S102). As shown in FIG. 2B, the resist pattern 130 is processed so that the cutting region 120 defined by a scribe line or the like on the surface of the semiconductor substrate W is exposed. The resist pattern 130 is processed by a photolithography process.

  Next, a fine groove is formed on the surface of the semiconductor substrate W (S104). 2C, using the resist pattern 130 as a mask, a fine groove 140 (hereinafter referred to as a fine groove or a groove on the surface side for convenience) is formed on the surface of the semiconductor substrate W. The Such a groove can be formed by dry etching, for example, and is preferably formed by anisotropic plasma etching (reactive ion etching) which is anisotropic dry etching. The width Sa of the fine groove 140 is substantially equal to the width of the opening formed in the resist pattern 130, and the width Sa of the fine groove 140 is, for example, several μm to several tens of μm. Further, the depth is, for example, about 10 μm to 100 μm, and is formed deeper than at least a depth at which a functional element such as a light emitting element is formed. When the fine groove 140 is formed by a general dicing blade, the interval S between the cutting regions 120 becomes as large as about 40 to 60 μm as a total of the margin width considering the groove width and chipping amount of the dicing blade itself. On the other hand, when the fine groove 140 is formed by a semiconductor process, not only the groove width itself but also the margin width for cutting can be made narrower than the margin width when a dicing blade is used, in other words, The interval S between the cutting regions 120 can be reduced. For this reason, the number of obtained semiconductor pieces can be increased by arranging the light emitting elements at a high density on the wafer. In this embodiment, the “front side” means a surface side on which a functional element such as a light emitting element is formed, and the “back side” means a surface side opposite to the “front side”.

  Next, the resist pattern is peeled off (S106). As shown in FIG. 2D, when the resist pattern 130 is peeled from the surface of the semiconductor substrate, the fine groove 140 formed along the cutting region 120 is exposed on the surface. Details of the shape of the fine groove 140 will be described later.

  Next, an ultraviolet curable dicing tape is attached (S108). As shown in FIG. 3E, a dicing tape 160 having an adhesive layer on the light emitting element side is attached. Next, half dicing is performed along the fine groove 140 by a dicing blade from the back side of the substrate (S110). The positioning of the dicing blade can be done by placing an infrared camera on the back side of the substrate and indirectly detecting the fine groove 140 through the substrate, or by placing a camera on the surface side of the substrate and directly positioning the fine groove 140. The detection method and other known methods can be used. By such positioning, as shown in FIG. 3F, half dicing is performed by a dicing blade, and a groove 170 is formed on the back surface side of the semiconductor substrate. The groove 170 has a depth that reaches the fine groove 140 formed on the surface of the semiconductor substrate. Here, the fine groove 140 is formed with a width narrower than the groove 170 on the back surface side by the dicing blade. However, if the fine groove 140 is formed with a width narrower than the groove 170 on the back surface side, only the dicing blade is formed. This is because the number of semiconductor pieces that can be obtained from one wafer can be increased as compared with the case of cutting the semiconductor substrate. In addition, if it is possible to form fine grooves of about several μm to several tens of μm as shown in FIG. It is not easy to form a fine groove having such a depth. Therefore, as shown in FIG. 3F, the half dicing from the back surface by the dicing blade is combined.

  Next, the dicing tape is irradiated with ultraviolet rays (UV), and an expanding tape is attached (S112). As shown in FIG. 3G, the dicing tape 160 is irradiated with ultraviolet rays 180, and the adhesive layer is cured. Thereafter, an expanding tape 190 is attached to the back surface of the semiconductor substrate.

  Next, the dicing tape is peeled off, and the expanding tape is irradiated with ultraviolet rays (S114). As shown in FIG. 3H, the dicing tape 160 is peeled off from the surface of the semiconductor substrate. Further, the expanding tape 190 on the back surface of the substrate is irradiated with ultraviolet rays 200, and the adhesive layer is cured. The expanding tape 190 has a stretchable base material, stretches the tape so that it is easy to pick up semiconductor pieces separated after dicing, and extends the interval between the light emitting elements.

  Next, picking and die mounting of the separated semiconductor pieces are performed (S116). As shown in FIG. 3I, the semiconductor piece 210 picked from the expanding tape 190 is mounted on the circuit board 230 via a fixing member 220 such as a conductive paste such as an adhesive or solder.

  Next, details of half dicing by a dicing blade will be described. FIG. 5 shows a state in which an enlarged cross-sectional view when half dicing is performed by the dicing blade shown in FIG. 3 highlights the light emitting element 100 formed on the surface of the substrate, but FIG. 5 does not clearly show the light emitting element on the surface of the substrate, but the light emitting element is the same as in FIG. It is assumed that it is formed on the surface.

  As shown in FIG. 5, the dicing blade 300 cuts the semiconductor substrate W from the back surface while rotating along the fine grooves 140 to form the grooves 170 in the semiconductor substrate W. The dicing blade 300 is, for example, a disc-shaped cutting member. Here, an example in which the tip portion has a constant thickness is shown, but a dicing blade in which the tip portion is tapered may be used. The groove 170 (kerf width) formed by the dicing blade 300 has a width substantially equal to the thickness of the dicing blade 300, and the groove 170 is processed to a depth that leads to the fine groove 140. The dicing blade 300 is aligned outside the semiconductor substrate W in a direction parallel to the back surface of the semiconductor substrate W. Further, a stepped portion 800 formed by the step formed in the connecting portion between the groove 170 and the fine groove 140 by moving by a predetermined amount in the direction Y perpendicular to the back surface of the semiconductor substrate W is desired in the Y direction. The semiconductor substrate W is aligned in the thickness direction so as to have the thickness T. Then, after alignment is performed outside the semiconductor substrate W, at least one of the dicing blade 300 or the semiconductor substrate W is moved in a direction parallel to the back surface of the semiconductor substrate W while the dicing blade 300 is rotated. Thus, the groove 170 is formed in the semiconductor substrate W. The step portion 800 is a portion between the step formed at the connection portion between the groove 170 and the fine groove 140 and the surface of the semiconductor substrate W. In other words, the width of the groove 170 and the width of the fine groove 140 are the same. It is a step-shaped part formed by the difference between.

  When half dicing is performed by the dicing blade 300, a dicing tape 160 is attached to the surface of the substrate. The dicing tape 160 includes a tape base material 162 and an adhesive layer 164 laminated thereon. The adhesive layer 164 is made of an ultraviolet curable resin, has a certain viscosity or viscosity before being irradiated with ultraviolet rays, and has a property of being cured and losing its adhesiveness when irradiated with ultraviolet rays. For this reason, when the dicing tape 160 is affixed, the adhesive layer 164 adheres to the surface of the substrate including the fine grooves 140 and holds them so that the semiconductor pieces do not leave after dicing.

  In the cutting line A2 of FIG. 5, during the cutting of the semiconductor substrate W, the vibration B and the vibration B and the semiconductor substrate W via the inner wall of the groove 170 are caused by the rotation of the dicing blade 300 or the relative movement of the dicing blade 300 and the semiconductor substrate W. A cutting pressure P is applied. When the semiconductor substrate W is pressed in the Y direction by the cutting pressure P, the viscous adhesive layer 164 flows and enters the fine groove 140. In addition, the vibration B is transmitted to the vicinity of the fine groove 140 to promote the flow of the adhesive layer 164. Further, in the cutting by the dicing blade 300, a cutting water flow (jet water flow) mixed with chips is supplied to the groove 170, and the pressure P1 is applied in the direction in which the fine groove 140 expands by the cutting water flow, so that the adhesive layer 164 enters. It can be further encouraged. As a result, in the case of the fine groove not having the forward tapered shape of this embodiment described later, for example, the adhesive layer 164 may enter into the fine groove 140 having a width of about 5 μm with an entry depth of about 10 μm. . Therefore, in this example, even if the method of manufacturing the semiconductor piece by reducing the groove width on the front surface side than the groove width on the back surface side for the reason of improving the number of obtained semiconductor pieces, the groove on the back surface side When formed with a rotating cutting member, the number of semiconductor pieces obtained is somewhat sacrificed, but forward-tapered fine grooves described later are formed.

  Note that, in the cutting line A1 after the dicing is completed, pressure is applied so that the fine groove 140 is narrowed in the width direction during the cutting of the adjacent cutting line A2, so that the adhesive layer 164 entering the fine groove 140 further enters the inside. It will be easier. In the cutting line A3 on the opposite side before cutting, since only the adhesive layer 164 is stuck, it is considered that the amount of the adhesive layer 164 entering the fine groove 140 is relatively small.

  When the half dicing by the dicing blade 300 is completed, the expanding tape 190 is attached to the back surface of the substrate, and then the dicing tape 160 is irradiated with ultraviolet rays 180. The adhesive layer 164 irradiated with ultraviolet rays is cured and loses its adhesive strength (FIG. 3G). Next, the dicing tape is peeled off from the substrate surface. FIG. 6 is a cross-sectional view illustrating the remaining adhesive layer when the dicing tape is peeled off. An expanded tape 190 and a tape base material 192 affixed to the back surface of the substrate, and an adhesive layer 194 laminated thereon, and the cut semiconductor pieces are held by the adhesive layer 194.

  When the dicing tape 160 and the substrate surface are peeled off, the adhesive layer 164a that has entered the fine groove 140 has penetrated to a deep position. It may become. Since the uncured adhesive layer 164 has adhesiveness, when the adhesive layer 164 is peeled off from the substrate surface, the uncured adhesive layer 164a is cut and the adhesive layer 164a remains in the fine groove 140. Alternatively, it may remain attached to the substrate surface again. Even in the cured state, the pressure-sensitive adhesive layer 164a penetrates deeply into the narrow microgrooves, so that it can be broken off by the stress at the time of peeling. If the remaining adhesive layer 164b is reattached to the surface of the light-emitting element, the light amount of the light-emitting element is reduced, the light-emitting element is regarded as a defective product, and the yield is reduced. Further, even if the semiconductor chip is other than the light emitting element, other adverse effects are assumed such as the adhesive layer 164b remaining, which is determined to be defective by an appearance inspection of the chip. For this reason, it is not preferable that the adhesive layers 164a and 164b remain on the substrate surface when the dicing tape is peeled off. In this example, by changing the shape of the fine groove formed on the substrate surface to a forward taper shape as described later, the adhesive layer remains in the fine groove or the substrate surface when the dicing tape is peeled off. Try to suppress.

  Note that in the case where the plurality of light emitting elements 100 are formed in a mesa shape, the light emitting element 100 forms a convex portion, a concave portion is formed between the light emitting element 100 and another light emitting element 100, and the fine groove 140 is formed in the concave portion. Often formed. In such a configuration, not only the convex part but also the adhesive layer 164 is pasted not only to the entrance part of the fine groove 140 formed in the concave part, but the cutting water flow mixed with chips enters the substrate surface side. A configuration that prevents this may be considered. However, in order for the adhesive layer 164 to follow the entrance portion of the fine groove 140, a dicing tape having a sufficient thickness of the adhesive layer 164 is required, so that the adhesive layer 164 becomes more fine. It becomes easy to get deep into. Therefore, under such conditions that the adhesive layer 164 easily penetrates into the fine groove 140, applying the forward tapered fine groove according to this embodiment described later has a higher effect on the remaining adhesive layer 164. can get.

  Further, when the fine groove perpendicular to the surface of the semiconductor substrate is formed, the adhesive layer 164 penetrates deeper than the distance of the groove width of the fine groove, that is, the adhesive layer 164a in the fine groove of the adhesive layer 164. In the case where the shape is vertically long, it is considered that when the adhesive layer 164 is peeled off, the adhesive layer 164 is easily peeled off due to the stress applied to the root portion of the adhesive layer 164a in the fine groove as compared with the case where the shape is not vertically long. Therefore, in the case where the forward taper shape of the present embodiment is not applied, in the manufacturing conditions such as the width of the fine groove and the thickness of the pressure-sensitive adhesive layer 164 such that the shape of the pressure-sensitive adhesive layer 164a in the fine groove is vertically long, this embodiment described later. By applying the forward-tapered fine groove, a higher effect can be obtained for the remaining adhesive layer 164.

  Next, the shape of the fine groove according to the embodiment of the present invention will be described. FIG. 7A is a cross-sectional view showing the shape of the first microgroove of this embodiment, and FIG. 7B illustrates ultraviolet irradiation to the adhesive layer that has entered the microgroove of FIG. 7A. It is a figure to do.

As shown in FIG. 7A, the fine groove 400 of the present embodiment is inclined so that the opening width Sa1 is narrowed from the opening width Sa1 on the substrate surface to the width Sa2 (Sa1> Sa2) at the bottom of the depth D. The opposite side surfaces 402 and 404 are included (this inclination is referred to as a forward tapered shape). In other words, the fine groove 400 has a shape in which the width gradually decreases from the opening width Sa1 to the depth D of the surface of the semiconductor substrate W. Further, the side surfaces 402 and 404 are not straight, but have a shape extending downward at a steep angle on the lower side rather than on the upper side of the groove. Such a groove shape is formed by switching the etching conditions during the formation of the groove (details will be described later). The opening width Sa1 is, for example, about several μm to several tens of μm. The depth D is deeper than the depth at which a circuit such as a light emitting element is formed. When the groove 170 is formed from the back side, the stepped portion 800 formed due to the difference in width between the groove 170 and the fine groove 400 is damaged. Do not make the depth. When the fine groove 400 is too shallow, when the groove 170 is formed from the back surface side, the stepped portion 800 may be damaged by the stress caused by the dicing blade 300. Therefore, it is necessary to set the depth so as not to be damaged. On the other hand, when the fine groove 400 is too deep, the strength of the semiconductor substrate is weakened by the deep groove, so that it becomes difficult to handle the semiconductor substrate W in the process after forming the fine groove 140. Therefore, it is preferable not to form deeper than necessary. The fine groove 400 is preferably formed by anisotropic dry etching, and the inclination angles of the side surfaces 402 and 404 can be appropriately selected by changing the shape of the photoresist, etching conditions, and the like. Note that the shape in FIG. 7A is a shape in which there is no portion (corner portion) where the angle of the side surface of the groove changes discontinuously at the boundary portion between the first groove portion and the second groove portion. The boundary between the first groove portion on the upper side and the second groove portion on the lower side is not a clear shape. However, since the angle of the side surface is different between the upper side and the lower side of the fine groove 400, the first groove portion whose width gradually decreases from the front surface of the substrate toward the back surface, and the lower portion of the first groove portion. Second groove that is formed in communication and extends downward at a steeper angle than the angle of the first groove part without expanding the width of the lowermost part of the first groove part. It is an example of the surface side groove | channel (fine groove | channel) containing a part.

  As shown in FIG. 7B, a groove 170 having a kerf width Sb is formed by cutting the dicing blade 300, and the groove 170 is connected to the fine groove 400. The width (kerf width Sb) of the groove 170 is, for example, about 20 to 60 μm. A part of the adhesive layer 164 enters the forward tapered fine groove 400 due to the pressure from the dicing blade 300, vibration, or the like, and after applying the expanding tape, dicing is performed by ultraviolet rays 180 from the substrate surface side. The tape 160 is irradiated. At this time, since the microgroove 400 is processed into a forward tapered shape, the ultraviolet ray 180 is sufficiently shielded by the semiconductor substrate W and irradiates the adhesive layer 164a in the microgroove 400 sufficiently. The adhesive layer 164a is easily cured. As a result, when the dicing tape 160 and the substrate surface are peeled off, the adhesive layer 164a in the fine groove 400 is more adhesive than the vertical shape even if the opening width of the fine groove 400 is the same. The adhesive layer is easily removed from the substrate surface and the fine groove 400, and the adhesion layer is prevented from reattaching to the substrate surface. Further, since the forward tapered shape of the fine groove 400 is inclined, the groove shape is inclined, so that even when the adhesive layer 164a pushed into the fine groove 400 is not hardened, it is easy to come out as compared with the vertical fine groove. This facilitates the separation of the adhesive layer 164a.

  FIG. 7C is a cross-sectional view showing the shape of the second fine groove of this example. The second fine groove 410 has a groove portion of opposing side surfaces 412 and 414 inclined in the forward direction from the opening width Sa1 on the substrate surface to a width Sa2 in the middle of the depth D, and a substantially vertical facing from the width Sa2 to the bottom portion. And the groove portions of the side surfaces 412a and 414a. That is, a first groove portion whose width is gradually narrowed from the front surface of the substrate toward the back surface, and a groove portion formed in communication with the lower portion of the first groove portion, the lowermost portion of the first groove portion And a second groove portion extending downward at a steeper angle than the angle of the first groove portion without expanding the width of the first groove portion. Such a shape is formed, for example, by switching the etch condition during the formation of the groove. In addition, the shape of FIG.7 (C) is the part which the angle of the side surface of a groove | channel changes discontinuously in the boundary part of a 1st groove part and a 2nd groove part similarly to the shape of FIG. 7 (A). The shape has no (corner). The depth D of the inclined groove portion formed by the side surfaces 412 and 414 is preferably deeper than the depth at which the adhesive layer 164 enters when the dicing tape 160 is applied. Since the width of the groove portion deeper than the depth D is narrower than the groove width of the forward tapered shape, the ratio of the variation of the groove width due to vibration or stress of the dicing blade is larger than that of the forward tapered groove portion. Therefore, when the adhesive layer 164 has already entered the groove portion deeper than the depth D when the dicing tape 160 is applied, the adhesive layer 164 penetrates deeper into the groove due to vibration or stress of the dicing blade. Can do. Therefore, the depth D is preferably deeper than the depth at which the adhesive layer 164 enters in the state where the dicing tape 160 is attached.

  Further, it is preferable that the depth D is a depth that can maintain a state in which the adhesive layer 164 does not enter the groove portion deeper than the depth D after the groove on the back surface side is formed by the dicing blade. This is because when the adhesive layer 164 penetrates into a groove portion deeper than the depth D, it remains more easily during peeling. Other conditions such as the depth of the entire fine groove are the same as those in FIG.

  Here, if the fine groove is to be formed deeply only by the forward tapered shape as shown in FIG. 7A, the opening Sa1 needs to be widened. Further, if the fine groove 400 is formed deeply with only the forward taper shape while the opening Sa1 is narrow, the taper angle becomes steep, so that the adhesive layer 164 easily remains in the fine groove 400. On the other hand, in the shape of FIG. 7C, the width of the opening Sa1 can be easily formed as a fine groove having a desired depth while maintaining the width in which the adhesive layer is difficult to remain in the fine groove. If a fine groove having a desired depth can be formed, damage to the stepped portion is suppressed when the groove 170 having a width wider than the width of the fine groove 410 is formed from the back side compared to a case where the depth of the fine groove is shallow. The

  Further, when the fine groove perpendicular to the surface of the semiconductor substrate is formed, the adhesive layer 164 penetrates deeper than the distance of the groove width of the fine groove, that is, the adhesive layer 164a in the fine groove of the adhesive layer 164. When the shape is vertically long, compared to the case where the shape is not vertically long, when the pressure-sensitive adhesive layer 164 is peeled off, it tends to remain due to the stress applied to the root portion of the pressure-sensitive adhesive layer 164a in the fine groove. Therefore, in the manufacturing conditions such as the width of the fine groove and the thickness of the adhesive layer 164 such that the shape of the adhesive layer 164a penetrating into the fine groove becomes vertically long when it is assumed that a vertical fine groove shape is formed. It is preferable that the entrance portion of the fine groove has a forward taper shape as in FIG. That is, the groove width of the groove portion located below the forward tapered groove portion is narrower than the depth into which the adhesive layer enters when it is assumed that the entire fine groove 410 is formed with this groove width. In this case, if the entrance portion of the groove has a forward taper shape, a higher effect can be obtained for the remaining adhesive layer 164.

  When the groove 170 having the kerf width Sb is formed by cutting the dicing blade 300 with respect to the fine groove in FIG. 7C, the groove 170 is connected to the fine groove 410 as shown in FIG. 7B, a part 164a of the adhesive layer 164 enters the fine groove 410, but the depth D of the forward tapered groove portion (side surfaces 412 and 414) of the fine groove 410 is If the pressure-sensitive adhesive layer 164a is formed deeper than the depth into which the pressure-sensitive adhesive layer 164a enters, the pressure-sensitive adhesive layer 164a in the fine groove 410 is sufficiently irradiated with ultraviolet rays and easily cured. For this reason, when the dicing tape is peeled off, the adhesive layer is suppressed from remaining on the fine groove 410 or the substrate surface. Further, since the side surface of the fine groove 410 has an inclination, the adhesive layer 164a pushed into the fine groove 410 is easily removed even when the adhesive layer 164a is not cured, and the separation of the adhesive layer 164a is promoted.

  As described above, according to the present embodiment, the fine grooves 400 and 410 are configured to include a forward taper-shaped groove portion in which at least the opening width of the substrate surface is narrowed toward the bottom portion. Even if the pressure-sensitive adhesive layer enters the fine groove, the whole pressure-sensitive adhesive layer in the fine groove is irradiated with ultraviolet rays and cured, and compared with the case where the pressure-sensitive adhesive layer does not have a forward tapered shape, it becomes easy to lose its adhesiveness. Furthermore, since it is a forward taper shape, when the dicing tape is peeled off, the adhesive layer is prevented from being interrupted as compared with a case where the dicing tape is not peeled off, and is easily peeled off from the fine groove or the substrate surface as a unit. Further, the side surface of the fine groove is not a straight line shape as in the shape of FIG. 9A described later, and the lower side surface has a steeper angle than the upper side surface. Even when the width of the entrance portion is the same, a groove deeper than the shape of FIG. 9A can be formed. If a deep groove can be formed, when the groove 170 is formed from the back side, the stepped portion 800 is not easily damaged by the stress of the dicing blade. Therefore, when the shape of FIG. 9A is compared with the shape of FIGS. 7A and 7C, the shape of FIG. 7A and FIG. It is easy to balance the damage of the parts.

  7A to 7D each disclose a form in which the opening width Sa1 on the substrate surface is narrower than the width of the groove 170. This is because the opening width Sa1 on the substrate surface is This is because if the configuration is narrower than the width of the groove 170, the number of obtained semiconductor pieces can be increased as compared with the method of full dicing with the width of the groove 170. Here, in general, in order to increase the number of obtained semiconductor pieces, the groove on the surface side has a narrower vertical shape than the groove on the surface side formed by isotropic etching or a dicing blade. It is better to form the groove by anisotropic dry etching, which is easy to form, but by adopting anisotropic dry etching, if the groove shape is simply narrow and vertical, the adhesive layer remains. It is not preferable from the viewpoint. On the other hand, paying attention to the remaining adhesive layer, isotropic etching in which the opening of the fine groove does not become a vertical shape rather than forming the groove on the surface side by anisotropic dry etching that becomes a narrow groove with a vertical shape. However, it is difficult to form narrow and deep grooves by isotropic etching. Therefore, in this embodiment, even in the case of anisotropic dry etching, the number of semiconductor pieces obtained can be increased and the remaining adhesive layer can be suppressed by forming fine grooves having the shapes shown in FIGS. Can be achieved.

  FIGS. 8A and 8B are comparative examples when the fine groove is processed into an inversely tapered shape. As shown in FIG. 8A, the fine groove 500 is processed into a so-called reverse tapered groove having inclined side surfaces 502 and 504 that face each other so that the bottom width Sa2 is larger than the opening width Sa1. Yes. The shape in which the width on the bottom side widens in this way is the flow rate of the etching gas (Cl 2 etc.) contained in the etching gas and the side wall protection even when using isotropic etching or anisotropic dry etching. For example, the balance with the flow rate of the protective film forming gas (C4F8 or the like) is set so as to be processed into a reverse taper shape. As shown in FIG. 8B, when a part 164a of the adhesive layer 164 enters the minute groove 500 having a reverse taper shape, the opening of the opening width Sa1 is narrowed. Therefore, the peripheral edge 165 (the painted portion in the figure) of the adhesive layer 164a is not sufficiently irradiated with ultraviolet rays, and a certain amount of uncured adhesive layer 165 tends to remain. For this reason, when the dicing tape is peeled off, the adhesive layer 165 which is sticky easily breaks compared to the case of the forward taper shape, and remains in the fine groove or reattaches to the substrate surface or the like. End up. Furthermore, since it has a reverse taper shape, the hardened adhesive layer 164 pushed into the fine groove 500 is not easily removed.

  8C and 8D are comparative examples when the fine groove is processed into a vertical shape. As shown in FIG. 8C, the fine groove 510 is processed into a so-called vertical groove including side surfaces 512 and 514 that are perpendicular to each other and have an opening width Sa1 on the substrate surface. Such a shape is formed when general anisotropic dry etching is employed. As shown in FIG. 8D, the pressure-sensitive adhesive layer 164a that has entered the vertical micro-grooves 510 penetrates deeply into the width Sa1 of the micro-grooves. Thus, the entire adhesive layer 164a is not sufficiently irradiated with the ultraviolet rays 180, and the adhesive layer 166 that is part of the peripheral edge thereof is likely to be uncured. The uncured pressure-sensitive adhesive layer 166 is smaller than the pressure-sensitive adhesive layer 165 in the reverse taper shape of FIG. 8A, but such a pressure-sensitive adhesive layer 166 remains on the fine groove 510 or the substrate surface when the dicing tape is peeled off. Or may reattach.

  FIG. 9A is a comparative example when the fine groove 520 is processed into a forward tapered shape having only the straight side surfaces 522 and 524. Such a shape is obtained, for example, in anisotropic dry etching between the flow rate of an etching gas (Cl 2 or the like) contained in an etching gas and the flow rate of a protective film forming gas (C 4 F 8 or the like) for protecting the side walls. It is formed by setting the balance so as to be processed into a forward tapered shape. As shown in FIG. 9A, the pressure-sensitive adhesive layer 164a that has entered the fine groove 520 having a forward taper shape has an ultraviolet ray 180 applied to the entire pressure-sensitive adhesive layer 164a as compared with the shape of FIGS. 8A and 8C. Is easily irradiated. Therefore, an uncured adhesive layer is unlikely to be generated after irradiation with the ultraviolet ray 180, and the adhesive layer hardly remains or reattaches to the fine groove 520 or the substrate surface when the dicing tape is peeled off. However, the shape of FIG. 9A is different from the shapes of FIGS. 7A and 7C, and the side surfaces 522 and 524 of the fine groove 520 are configured by straight side surfaces having a constant angle. Therefore, if the width Sa1 of the entrance portion of the fine groove is compared under the same condition, a groove deeper than that shown in FIGS. 7A and 7C cannot be formed. When a deep groove cannot be formed and becomes a shallow groove, as described above, when the groove 170 is formed from the back surface side, the stepped portion 800 is likely to be damaged by the stress of the dicing blade. Therefore, when the shape of FIG. 9A is compared with the shape of FIGS. 7A and 7C, the shape of FIG. 7A and FIG. It is easy to balance the damage of the parts.

  In FIG. 9B, the fine groove 530 is formed in communication with the first groove portion (532, 534) whose width gradually decreases from the front surface to the back surface of the substrate, and below the first groove portion. A second groove portion (532a, 534a) extending downward at a steeper angle than the angle of the first groove portion without expanding the width of the lowermost portion of the first groove portion. ). For example, the upper groove portion corresponding to the first groove portion is formed by isotropic etching, and the lower groove portion corresponding to the second groove portion is formed by anisotropic dry etching. It can be realized by forming. In FIG. 9B, as in FIG. 9A, the entrance portion of the fine groove 530 has a forward taper shape, so that the adhesive layer is compared with the shape of FIGS. 8A and 8C. It becomes difficult to remain on the fine groove 530 or the substrate surface. Further, as compared with the shape of FIG. 9A, since the deeper groove can be formed even if the width Sa1 of the entrance portion of the fine groove 530 is the same, breakage of the stepped portion 800 is suppressed. However, the shape of FIG. 9B is compared with the shapes of FIGS. 7A and 7C between the first groove portion and the second groove portion, and the side surfaces 532, 532a and 534 of the groove. The presence of a portion (corner portion) where the angle of 534a changes discontinuously, when the adhesive layer penetrates into the second groove portion, the entire adhesive layer is difficult to be irradiated with ultraviolet rays 180, Hardened adhesive layer is likely to occur. Further, when the dicing tape 160 and the substrate surface are peeled off due to the presence of portions (corner portions) where the angles of the groove side surfaces 532, 532a and 534, 534a change discontinuously, the second groove The adhesive layer 164A that has penetrated to the portion is caught in the corners and is easily broken, and the remaining of the adhesive layer 164A is promoted. Therefore, when the shape of FIG. 9B is compared with the shapes of FIGS. 7A and 7C, the shape of FIGS. It is easy to balance the damage of the parts.

  FIG. 9C shows a first groove portion in which the fine groove 540 is composed of linear side surfaces 542 and 544 whose width gradually decreases from the front surface to the back surface of the substrate, and below the first groove portion. And a second groove portion formed of side surfaces 542a and 544a extending substantially vertically downward. In such a shape, for example, a portion corresponding to the first groove portion is formed using only the tip portion of a dicing blade having an acute-angled tip portion, and a portion corresponding to the second groove portion is thin. This can be realized by using a dicing blade. Also in the case of the shape of FIG. 9C, as in the case of the shape of FIG. 9B described above, the portions where the angles of the side surfaces 542, 542a and 544, 544a of the fine groove change discontinuously (corner portions). ) And the shapes of FIGS. 7A and 7C are compared, the shapes of FIGS. It is easy to balance.

  Next, the manufacturing method of the fine groove | channel of a present Example is demonstrated. FIG. 10 is a cross-sectional view showing the steps of the method for manufacturing the fine groove shown in FIGS. 7 (A) and 7 (C). As shown in FIG. 10A, a photoresist 600 is applied to the surface of a semiconductor substrate W (GaAs substrate) on which a plurality of light emitting elements are formed. The photoresist 600 is, for example, an i-line resist having a viscosity of 100 cpi and is formed to a thickness of about several μm. An opening 610 is formed in the photoresist 600 using a known photolithography process, for example, an i-line stepper and 2.38% TMAH developer. The opening 610 is formed to expose the cutting region 120 as described with reference to FIG.

  Next, as shown in FIG. 10B, the semiconductor substrate W is anisotropically dry etched using the resist pattern 600 in which the openings 610 are formed as an etching mask. As an example, inductively coupled plasma (ICP) is used as a reactive ion etching (RIE) apparatus. By adding a CF-based gas as an etching gas, a protective film 630 is formed on the sidewall of the groove 620 simultaneously with the etching. Radicals and ions are generated by the plasma of the reactive gas, but the side wall of the groove 620 is attacked only by radicals, and the bottom is attacked by both radicals and ions, making it easy to etch, and anisotropic etching is achieved. . Here, the etching conditions such as the forward tapered groove are formed by adjusting the etching conditions such as the output of the etching apparatus, the gas flow rate, and the time. For example, by increasing the flow rate of an etching gas (Cl2 or the like) included in the etching gas or reducing the flow rate of a CF-based gas (C4F8 or the like) that is a gas for forming a sidewall protective film, Since the protective film 630 to be formed becomes thin, the angle of the side wall of the groove becomes a steep angle with respect to the depth direction (that is, an angle close to vertical). Conversely, by reducing the flow rate of the etching gas (Cl2 or the like) contained in the etching gas or increasing the flow rate of the CF-based gas (C4F8 or the like) that is a gas for forming the sidewall protective film, the sidewall of the groove Since the protective film 630 formed on the substrate becomes thick, the angle of the side wall of the groove becomes a gentle angle with respect to the depth direction. As an example, the etching conditions are: inductively coupled plasma (ICP) power 500 W, bias power 50 W, pressure 3 Pa, etching gas: Cl 2 = 150 sccm, BCl 3 = 50 sccm, C 4 F 8 = 50 sccm, substrate temperature 20 ° C., etching time 20 minutes. is there.

  Next, as shown in FIG. 10C, the etching conditions are switched so that the angle becomes steeper than the forward taper angle formed in FIG. For example, by increasing the flow rate of an etching gas (Cl 2 or the like) included in the etching gas, or by reducing the flow rate of a CF-based gas (C 4 F 8 or the like) that is a gas for forming the sidewall protective film, FIG. The groove portion 640 having a steeper angle than the angle of the side wall of the groove 620 formed in (1) is formed. As an example, the etching conditions are: inductively coupled plasma (ICP) power 500 W, bias power 50 W, pressure 3 Pa, etching gas: Cl 2 = 200 sccm, BCl 3 = 50 sccm, C 4 F 8 = 35 sccm, substrate temperature 20 ° C., etching time 20 minutes. is there. When forming a fine groove, the thickness of the side wall protective film 630 tends to be thinner on the bottom side than on the upper side, so that the etching strength is increased in the middle to adhere to the bottom side of the already formed groove. The side wall protective film 630 is shaved and the side walls are easily exposed. As a result, the groove width on the bottom side of the already formed groove slightly widens and the groove extends downward. On the other hand, since the thick side wall protective film 630 is attached to the upper side of the already formed groove, the side wall protective film 630 is not etched until the side wall is exposed unless the etching conditions are extremely increased. The shape of the upper part (entrance part) of the groove is kept unchanged.

  In addition, when reducing the flow volume of CF type gas (C4F8 etc.) which is gas for forming a side wall protective film, it is preferable to reduce in the range which does not stop completely. This is because if the gas for forming the sidewall protective film is stopped, the etching strength in the sidewall direction becomes excessive, and a groove portion having a width extending toward the lower side of the fine groove is formed. In this way, when a groove portion having a width extending toward the lower portion of the fine groove is formed, if the adhesive layer 164a enters the groove portion, the entire adhesive layer 164a is not easily irradiated with the ultraviolet ray 180, and FIG. This is because the adhesive layer 164a is likely to remain as in the case of A). As described above with reference to FIG. 5, when forming a groove with a rotating cutting member such as a dicing blade from the back surface of the substrate with respect to the fine groove, for example, about 10 μm in a fine groove having a width of about 5 μm. In some cases, the adhesive layer penetrates to a depth greater than expected, for example, the adhesive layer penetrates at the penetration depth. Therefore, when there is no special reason for forming a groove portion whose width increases toward the lower side of the fine groove, such a groove portion is not formed from the viewpoint of suppressing the remaining adhesive layer. Further, when the etching strength in the side wall direction becomes excessive by stopping the gas for forming the side wall protective film, the side wall protective film 630 is scraped until the side wall on the upper side (entrance portion) of the groove is exposed. There is. This is considered to occur because the concentration of fresh etching gas is higher in the entrance portion of the fine groove than in the bottom portion. In this case, etching is performed so that the upper side of the groove extends in the width direction, which may affect the element formation region in some cases. Therefore, it is preferable to switch to an etching strength within a range where the upper side wall of the groove is not exposed.

  After the formation of the fine groove in FIG. 10C is completed, the resist 600 is removed by oxygen ashing as shown in FIG. In this way, the fine grooves 400 and 410 shown in FIGS. 7A and 7C are obtained.

  As described above, in the fine groove manufacturing method of the present embodiment, the formation of the fine groove is started with the first etching strength at which the width of the fine groove is gradually narrowed in the depth direction, and the fine groove is being formed. Then, the dry etching conditions are switched from the front surface to the back surface of the substrate by changing the dry etching conditions to a second etching strength that is lower than the first etching strength and that extends downward without increasing the width of the entrance portion of the groove on the front surface side. A fine groove that does not have a portion where the width of the groove widens is formed. Since the etching is performed with the first etching strength at which the width of the fine groove is gradually narrowed in the depth direction, the shape in which the adhesive layer 164a is prevented from remaining as compared with the shapes in FIGS. The fine groove is formed. Further, during the formation of the fine groove, there is a portion where the width of the entrance portion of the fine groove is not widened but the dry etching strength is increased to the second etching strength that extends downward, and the width is widened toward the lower portion of the groove. Since no fine groove is formed, a fine groove having no corner as shown in FIG. 9C is formed. Furthermore, compared with the forward tapered shape having only the straight side surface as shown in FIG. 9A, even if the width of the entrance portion of the fine groove is the same, a deeper fine groove is formed. The

  In addition, the manufacturing method in the above-described embodiment is merely an example, and is not necessarily limited to the manufacturing process shown in FIG. For example, although the opening 610 of the photoresist 600 formed in FIG. 10A has an opening side surface perpendicular to the substrate surface, the shape disclosed in FIGS. 7A and 7C can be easily formed. In addition, the opening width may be gradually increased upward from the substrate surface. If a photoresist having such a shape is used, the etching range gradually increases from a thin portion to a thick portion of the photoresist, so that a forward tapered shape can be easily formed. Also, the etching conditions need not be switched only once, and may be performed a plurality of times as necessary, such as gradually increasing the etching strength.

  Next, breakage of the step portion formed by the difference in width between the fine groove and the groove on the back surface side will be described. 11A is a cross-sectional view when half dicing is performed by the dicing blade shown in FIG. 3F, FIG. 11B is an enlarged view of the step portion shown in FIG. 11A, and FIG. C) shows breakage of the stepped portion.

  As described above, a plurality of light emitting elements 100 are formed on the surface of the semiconductor substrate W, and each light emitting element 100 is separated by a cutting region 120 defined by a scribe line having a spacing S or the like. It is assumed that a fine groove 140 (a vertical groove shown in FIG. 8C) having a width Sa is formed in the cut region 120 by anisotropic dry etching. A groove 170 having a width substantially equal to the kerf width Sb is formed in the semiconductor substrate W by cutting from the back surface of the semiconductor substrate W while rotating the dicing blade 300 having the kerf width Sb. Since the kerf width Sb is larger than the width Sa of the fine groove 140, when the groove 170 is formed, the cutting region 120 has a difference between the width Sb and the width Sa, in other words, the positions of the side surfaces of the fine groove 140 and the groove 170. Thus, a cantilever-shaped stepped portion 800 having a thickness T is formed. If the center of the dicing blade 300 and the center of the fine groove 140 are completely coincident with each other, the length of the stepped portion 800 extending in the lateral direction is (Sb−Sa) / 2.

  When cutting with the dicing blade 300 is performed, the flat surface at the tip of the dicing blade 300 presses the semiconductor substrate W in the Y direction, whereby a force F is applied to the stepped portion 800, thereby Stress concentrates on the corner C. When the stress on the corner portion C exceeds the breaking stress of the wafer, the stepped portion 800 is damaged (chip, crack, picking, etc.) as shown in FIG. In particular, a compound semiconductor substrate such as GaAs is weaker than a silicon substrate, so that the stepped portion 800 is easily damaged. If the stepped portion 800 is damaged, a margin M for cutting the stepped portion 800 must be secured. This is because the interval S between the cutting regions 120 is equal to or larger than the margin M. This means that the number of obtained semiconductor pieces is reduced. Therefore, it is preferable to suppress breakage of the stepped portion 800.

  There are mainly the following three factors that have a high influence on the stress that causes the stepped portion 800 to be damaged. First, the shape of the tip of the dicing blade, second, the thickness T of the stepped portion 800, and third, the size of the step at the stepped portion, that is, a dicing blade 300 having a certain thickness is used. Is the amount of misalignment between the fine groove 140 and the groove 170. As in this example, the formation of the fine groove is started with the first etching strength at which the width of the fine groove is gradually narrowed in the depth direction. A case where a fine groove is formed with only the first etching strength by switching the dry etching conditions to the second etching strength that has a strong etching strength and does not widen the width of the entrance portion of the groove on the surface side. Compared to the above, since deeper fine grooves are formed, the thickness T of the stepped portion 800 becomes thicker. Therefore, even if the shape and the amount of positional deviation of the tip portion of the dicing blade are the same, breakage of the step portion is suppressed.

  Next, application examples of the embodiment of the present invention will be described. In this application example, the semiconductor substrate is divided by grinding (back grinding) from the back surface of the semiconductor substrate to the fine grooves on the front surface side of the semiconductor substrate without forming the back surface groove 170 in the previous embodiment. To do. Specifically, instead of attaching the dicing tape in step S108 in FIG. 1, a backgrinding tape is attached to the surface of the substrate. The dicing tape may be used as it is as a back grinding tape. Then, instead of the half dicing in step S110 in FIG. 1, back grinding is performed until the fine grooves on the surface side are reached. The back grind is arranged so that the back surface of the substrate can be seen in the same way as half dicing.For example, by moving the rotating grindstone in the horizontal or vertical direction, the thickness of the substrate is entirely increased until the surface side fine grooves are exposed. make it thin. Subsequent steps may be the same as those in FIG. When the strength of the substrate after back grinding becomes a problem, a so-called rib structure may be formed by not grinding only the peripheral portion of the substrate.

  Here, during the back grinding process, vibration and cutting pressure are applied to the adhesive layer of the back grinding tape through the inner wall of the fine groove due to rotation of the grindstone or relative movement of the grindstone and the semiconductor substrate. . When the semiconductor substrate is pressed by the cutting pressure, the viscous adhesive layer flows and enters the fine groove. Further, the vibration is transmitted to the vicinity of the fine groove, thereby promoting the flow of the adhesive layer. In particular, in the case of a fine groove having a width of several μm to several tens of μm, the pressure-sensitive adhesive layer easily penetrates deeper, and in the case of 10 μm or less, it becomes more remarkable.

  When the grinding with the grindstone is completed, an expanding tape is attached to the back surface of the substrate, and the back grinding tape is irradiated with ultraviolet rays. The pressure-sensitive adhesive layer irradiated with ultraviolet rays is cured, the adhesive strength is lost, and the backgrinding tape is peeled off from the substrate surface. Here, as described with reference to FIG. 6, the adhesive layer that has entered the fine groove on the surface side may remain in the groove or on the substrate surface when the backgrinding tape is peeled off. Therefore, in order to suppress the adhesive layer from remaining when the backgrinding tape is peeled off, the fine groove of the embodiment described with reference to FIGS. 7 and 10 may be applied. By applying the fine grooves shown in FIGS. 7 and 10, not only the adhesion layer remains but also a deeper groove is formed, so that the amount of grinding can be reduced, and the ground semiconductor substrate ( It is easy to ensure the strength of the semiconductor piece).

  In this application example, grinding is performed halfway from the back surface of the semiconductor substrate to the fine grooves on the front surface side of the semiconductor substrate, and then the semiconductor substrate is subjected to stress such as tensile stress and bending stress to break the remaining portion. The semiconductor substrate may be divided by Further, when the depth of penetration of the adhesive layer is known in advance, the shape of the fine groove at a portion deeper than the depth of penetration of the adhesive layer may be any shape such as a shape spreading in the depth direction. This is because, if the adhesive layer does not penetrate, problems such as difficulty in being irradiated with ultraviolet rays are not promoted even if the adhesive layer has a shape extending in the depth direction.

  The application examples described above can be explained as follows. That is, a step of forming a groove on the front side by dry etching from the front surface to the back surface of the substrate, a step of attaching a holding member having an adhesive layer to the surface on which the groove on the front surface side is formed, A step of grinding the substrate from the back surface toward the groove on the front surface side, and a step of peeling the surface and the holding member after the grinding, wherein the width of the groove on the front surface side is in the depth direction. The formation of the groove on the surface side is started with the first etching strength gradually narrowing toward the surface, and the dry etching is switched to an etching strength stronger than the first etching strength during the formation of the groove on the surface side. The method of manufacturing a semiconductor piece for forming the groove on the surface side. According to the manufacturing method of this application example, not only the adhesion layer remains but also the strength of the semiconductor substrate after grinding can be easily secured.

  Further, in the manufacturing method according to the above application example, during the formation of the groove on the surface side, the etching strength is stronger than the first etching strength, and the width of the entrance portion of the groove on the surface side is not increased. The dry etching may be switched to a second etching strength that extends downward to form the groove on the surface side that does not have a portion whose width increases toward the bottom of the groove. In such a configuration, since the reverse taper shape or the like in which the adhesive layer is likely to remain is not formed, the adhesive layer can be prevented from remaining even when the depth of penetration of the adhesive layer of the tape is increased.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment, and various modifications can be made within the scope of the present invention described in the claims. Deformation / change is possible.

  For example, the groove 170 on the back surface side may reach the vicinity of the fine groove on the front surface side, but may have a depth that does not communicate with the fine groove on the front surface side. That is, in the step of forming the groove 170 on the back surface side in FIG. 3F, the groove 170 on the back surface side may be formed while leaving a part of the thickness of the semiconductor substrate. In this case, the semiconductor substrate may be divided by applying a stress such as a tensile stress or a bending stress to the semiconductor substrate in a subsequent process and dividing the remaining portion.

  In addition, the manufacturing method of the present invention may be applied when individual elements are separated from a substrate that does not include a semiconductor such as glass or polymer.

  In addition, the suppression of damage in the present specification is not limited to suppression of chipping, cracking, etc. to the extent that it can be visually confirmed. The degree of suppression is not limited, including those that can be reduced. Also, the suppression of the residual adhesive layer does not mean that the residual is completely suppressed, and includes those that suppress the residual level to some extent and those that can reduce the possibility of the residual level to some extent. The degree of suppression is not limited. In addition, the shape of the fine groove of this embodiment in FIGS. 7 and 10 is merely an example, and the shape and angle of the inclination are not limited as long as the method is formed by switching the etching strength.

100: Light emitting element 120: Cutting region (scribe line)
130: Resist pattern 140: Surface side fine groove 160: Dicing tape 162: Tape base material 164: Adhesive layer 165, 166: Uncured adhesive layer 170: Back side groove 190: Expanding tape 210: Semiconductor chip 300 : Dicing blade 400, 410: Fine groove 402, 404, 412, 414, 412a, 414a: Side surface 500, 510, 520, 530, 540: Fine groove 502, 504, 512, 514, 522, 524, 532, 534: Side surface 600: photoresist 610: opening 620: groove 630: protective film 800: step portion

Claim 1 is a process of forming a groove on the front surface side by dry etching from the front surface to the back surface of the substrate, a step of attaching a holding member having an adhesive layer on the surface on which the groove on the front surface side is formed, A step of forming a groove on the back surface wider than the width of the groove on the front surface side from the back surface side of the substrate with the groove on the front surface side by a rotating cutting member, and after the formation of the groove on the back surface side said surface and provided with a step of peeling and the holding member, to start the formation of grooves in the surface side gradually narrows the dry etching toward the wide depth direction of grooves of the surface, the During the formation of the groove on the surface side, the flow rate of the protective film forming gas contained in the etching gas used for the dry etching is set within a range in which the flow rate of the protective film forming gas is not stopped from the first flow rate. Second flow less than the first flow rate Switch to, a method of manufacturing a semiconductor piece to form a groove in the surface side having no part broadening downward groove with gradually narrower toward the wide depth direction of the groove.
According to a second aspect of the present invention, in the course of forming the surface-side groove, the flow rate of the etching gas contained in the etching gas used for the dry etching is increased from the first flow rate to the second flow rate higher than the first flow rate. switch to the flow rate, the method of manufacturing a semiconductor element according to claim 1 for forming a groove in the surface side.
According to a third aspect of the present invention, the groove on the front surface side includes a first groove portion whose width gradually decreases from the front surface of the substrate toward the back surface, and a groove portion formed in communication with a lower portion of the first groove portion. there are, according to claim 1 or 2 and a top without spreading width than the lower portion of the width, the second groove portion extending downwardly at an acute angle than the angle of the first groove portion of the first groove portion The manufacturing method of the semiconductor piece of description.
According to a fourth aspect of the present invention, in the semiconductor piece manufacturing method according to the third aspect, the side surface of the groove on the front surface side does not have a corner portion between the first groove portion and the second groove portion.

According to claims 1 and 2 , both the suppression of the adhesive layer remaining on the surface of the semiconductor substrate and the suppression of breakage of the stepped portion of the semiconductor piece can be achieved in comparison with the case where the groove on the surface side is formed under a single etching condition. Cheap.
According to claim 3 , when the adhesive layer penetrates into the second groove portion, the semiconductor substrate is compared with the structure having the second groove portion having a width wider than the width of the lowermost portion of the first groove portion. It is possible to suppress the adhesive layer from remaining on the surface.
According to the fourth aspect , when the adhesive layer penetrates into the second groove portion, the surface of the semiconductor substrate is compared with a configuration having a corner portion between the first groove portion and the second groove portion. The remaining adhesive layer can be suppressed.

Next, as shown in FIG. 10B, the semiconductor substrate W is anisotropically dry etched using the resist pattern 600 in which the openings 610 are formed as an etching mask. As an example, inductively coupled plasma (ICP) is used as a reactive ion etching (RIE) apparatus. By adding a CF-based gas as an etching gas, a protective film 630 is formed on the sidewall of the groove 620 simultaneously with the etching. Radicals and ions are generated by the plasma of the reactive gas, but the side wall of the groove 620 is attacked only by radicals, and the bottom is attacked by both radicals and ions, making it easy to etch, and anisotropic etching is achieved. . Here, the etching conditions such as the forward tapered groove are formed by adjusting the etching conditions such as the output of the etching apparatus, the gas flow rate, and the time. For example, by increasing the flow rate of an etching gas ( Cl ₂ or the like) included in the etching gas, or by reducing the flow rate of a CF-based gas ( C ₄ F ₈ or the like) that is a gas for forming a sidewall protective film, Since the protective film 630 formed on the side wall of the groove becomes thin, the angle of the side wall of the groove becomes a steep angle with respect to the depth direction (that is, an angle close to vertical). Conversely, by reducing the flow rate of the etching gas ( Cl ₂ or the like) contained in the etching gas or increasing the flow rate of the CF-based gas ( C ₄ F ₈ or the like) that is a gas for forming the sidewall protective film. Since the protective film 630 formed on the side wall of the groove becomes thick, the angle of the side wall of the groove becomes a gentle angle with respect to the depth direction. As an example, the etching conditions are: inductively coupled plasma (ICP) power 500 W, bias power 50 W, pressure 3 Pa, etching gas: Cl ₂ = 150 sccm, BCl ₃ = 50 sccm, C ₄ F ₈ = 50 sccm, substrate temperature 20 ° C. The etching time is 20 minutes.

Next, as shown in FIG. 10C, the etching conditions are switched so that the angle becomes steeper than the forward taper angle formed in FIG. For example, by increasing the flow rate of an etching gas ( Cl ₂ or the like) included in the etching gas, or by reducing the flow rate of a CF-based gas ( C ₄ F ₈ or the like) that is a gas for forming a sidewall protective film, A groove portion 640 having a steeper angle than the angle of the side wall of the groove 620 formed in FIG. 10B is formed. As an example, etching conditions are: inductively coupled plasma (ICP) power 500 W, bias power 50 W, pressure 3 Pa, etching gas: Cl ₂ = 200 sccm, BCl ₃ = 50 sccm, C ₄ F ₈ = 35 sccm, substrate temperature 20 ° C. The etching time is 20 minutes. When forming a fine groove, the thickness of the side wall protective film 630 tends to be thinner on the bottom side than on the upper side, so that the etching strength is increased in the middle to adhere to the bottom side of the already formed groove. The side wall protective film 630 is shaved and the side walls are easily exposed. As a result, the groove width on the bottom side of the already formed groove slightly widens and the groove extends downward. On the other hand, since the thick side wall protective film 630 is attached to the upper side of the already formed groove, the side wall protective film 630 is not etched until the side wall is exposed unless the etching conditions are extremely increased. The shape of the upper part (entrance part) of the groove is kept unchanged.

In the case of reducing the flow rate of the CF-based gas is a gas for forming the sidewall protective film (C ₄ F _8, etc.), it is preferable to reduce completely not stop range. This is because if the gas for forming the sidewall protective film is stopped, the etching strength in the sidewall direction becomes excessive, and a groove portion having a width extending toward the lower side of the fine groove is formed. In this way, when a groove portion having a width extending toward the lower portion of the fine groove is formed, if the adhesive layer 164a enters the groove portion, the entire adhesive layer 164a is not easily irradiated with the ultraviolet ray 180, and FIG. This is because the adhesive layer 164a is likely to remain as in the case of A). As described above with reference to FIG. 5, when forming a groove with a rotating cutting member such as a dicing blade from the back surface of the substrate with respect to the fine groove, for example, about 10 μm in a fine groove having a width of about 5 μm. In some cases, the adhesive layer penetrates to a depth greater than expected, for example, the adhesive layer penetrates at the penetration depth. Therefore, when there is no special reason for forming a groove portion whose width increases toward the lower side of the fine groove, such a groove portion is not formed from the viewpoint of suppressing the remaining adhesive layer. Further, when the etching strength in the side wall direction becomes excessive by stopping the gas for forming the side wall protective film, the side wall protective film 630 is scraped until the side wall on the upper side (entrance portion) of the groove is exposed. There is. This is considered to occur because the concentration of fresh etching gas is higher in the entrance portion of the fine groove than in the bottom portion. In this case, etching is performed so that the upper side of the groove extends in the width direction, which may affect the element formation region in some cases. Therefore, it is preferable to switch to an etching strength within a range where the upper side wall of the groove is not exposed.

Claims (5)

Forming a groove on the front side by dry etching from the front surface to the back surface of the substrate;
A step of attaching a holding member having an adhesive layer to the surface on which the groove on the surface side is formed;
Forming a groove on the back surface having a width wider than the width of the groove on the front surface side from the back surface side of the substrate along the groove on the front surface side by a rotating cutting member;
Separating the front surface and the holding member after forming the groove on the back surface side,
The formation of the groove on the surface side is started with a first etching strength at which the width of the groove on the surface side is gradually narrowed in the depth direction, and the first etching is performed during the formation of the groove on the surface side. The dry etching is switched to a second etching strength which is lower than the strength and has a second etching strength which extends downward without expanding the width of the entrance portion of the groove on the surface side, and a portion where the width widens toward the lower portion of the groove. A method for producing a semiconductor piece for forming a groove on the surface side which does not have. In the course of forming the groove on the surface side, the flow rate of the protective film forming gas contained in the etching gas used for the dry etching is within a range in which the flow rate of the protective film forming gas is not stopped from the first flow rate. 2. The method of manufacturing a semiconductor piece according to claim 1, wherein the groove on the surface side is formed by switching to a second flow rate lower than the first flow rate. During the formation of the groove on the surface side, the flow rate of the etching gas contained in the etching gas used for the plasma etching is switched from the first flow rate to the second flow rate higher than the first flow rate. The method for manufacturing a semiconductor piece according to claim 1, wherein the groove on the surface side is formed. The groove on the front surface side is a first groove portion whose width gradually decreases from the front surface of the substrate toward the back surface, and a groove portion formed in communication with a lower portion of the first groove portion. 4. A second groove portion that extends downward at an angle steeper than the angle of the first groove portion without expanding the width of the lowermost portion of the groove portion. 5. Manufacturing method of semiconductor piece. 5. The method of manufacturing a semiconductor piece according to claim 4, wherein the side surface of the groove on the front surface side does not have a corner between the first groove portion and the second groove portion.

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