JP6994965B2 - How to lay resin for die bond - Google Patents

Description

The present invention relates to a method for laying a resin for die bonding.

When a semiconductor device chip is laminated on a substrate or another semiconductor device chip and bonded, a bonding method such as applying a silver paste has been conventionally used, but this type of bonding method is a method of applying a silver paste and applying the silver paste. Area control is very difficult. Therefore, a film called a die attach film (DAF) is attached to the back surface of the semiconductor wafer, and the film is divided together with the semiconductor wafer to form a device chip with a film, and the device chip is heated while heating. There is known a technique in which a film becomes an adhesive when placed on an adhesive destination.

However, in the so-called pre-dicing method, in which a wafer having a groove formed on its surface is ground and thinned to be divided into individual device chips, a film is attached to the divided semiconductor wafer and a laser beam is applied through the divided groove. For example, a step of dividing only the film is required (see, for example, Patent Document 1). The processing method shown in Patent Document 1 requires man-hours and costs for purchasing a laser processing apparatus and laser processing, as compared with a processing method for dividing a film at the same time as a device chip by dicing.

In order to solve the problem of the processing method shown in Patent Document 1, a liquid resin acting as an adhesive like a film is sprayed and laid on the back surface side of a wafer divided into device chips after dicing. A processing method was devised (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2014-220417 Japanese Unexamined Patent Publication No. 2017-041574

In the processing method shown in Patent Document 2, a liquid resin is applied to the back surface of the device chip to form a resin for die bonding. For this reason, in the processing method shown in Patent Document 2, the surface of the die-bonding resin tends to have an uneven shape due to the raised four corners of the device chip. As a result, the processing method shown in Patent Document 2 has a problem that it becomes difficult to uniformly adhere the entire back surface of the device chip to the bonding destination.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for laying a die bond resin capable of suppressing unevenness on the surface of the die bond resin on the back surface of the device chip. ..

In order to solve the above-mentioned problems and achieve the object, in the method of laying the resin for die bonding of the present invention, a protective member is attached to the surface where the device is formed in a plurality of regions partitioned by a plurality of planned division lines. This is a method of laying a die-bonding resin on the back surface of the wafer divided into individual device chips along the planned division line, and is a method of laying the die-bonding resin on the back surface of the wafer by heat. A die bond resin laying step for laying a liquid die bond resin that is softened and cured by irradiation with ultraviolet rays, a curing step for curing the laid die bond resin by irradiation with ultraviolet rays, and unevenness after performing the curing step. A flattening step of heating the surface of the die-bonding resin and pressing the softened surface of the die-bonding resin through a flat sheet to flatten the die-bonding resin, and a flattening of the die-bonding resin. It is characterized by comprising a sheet peeling step for stopping heating and peeling the sheet and the die-bonding resin in close contact with each other.

In the method of laying the die-bonding resin, in the flattening step, a roller may be rotated through the sheet to press the surface of the die-bonding resin to flatten it.

In the method of laying the resin for die bonding, the sheet may be a sheet made of polyolefin.

The method of laying the die-bonding resin of the present invention has an effect that the unevenness of the surface of the die-bonding resin on the back surface of the vise tip can be suppressed.

FIG. 1 is a perspective view showing an example of a wafer to be processed in the method of laying the die bond resin according to the first embodiment. FIG. 2 is a perspective view showing a state in which a dividing groove is formed in the wafer shown in FIG. 1 and a protective tape is attached to the surface side. FIG. 3 is a flowchart showing the flow of the method of laying the die bond resin according to the first embodiment. FIG. 4 is a perspective view showing a die bond resin laying step of the die bond resin laying method according to the first embodiment. FIG. 5 is a cross-sectional view of the wafer after the die bond resin laying step of the die bond resin laying method according to the first embodiment. FIG. 6 is a side view showing a curing step of the method of laying the die bond resin shown in FIG. FIG. 7 is a cross-sectional view of a wafer showing an enlarged VII portion in FIG. 6 after the curing step of the method of laying the die bond resin shown in FIG. FIG. 8 is a perspective view showing a flattening step of the method of laying the die bond resin shown in FIG. FIG. 9 is a cross-sectional view of a wafer showing a flattening step of the method of laying the die bond resin shown in FIG. FIG. 10 is a cross-sectional view of a wafer or the like after the sheet peeling step of the method of laying the die bond resin shown in FIG. FIG. 11 is a cross-sectional view of a wafer in which the XI portion in FIG. 10 is enlarged and shown. FIG. 12 is a cross-sectional view of a wafer showing a flattening step of the method of laying the die bond resin according to the second embodiment. FIG. 13 is a cross-sectional view of a wafer or the like showing a part of the sheet peeling step of the method for laying the die bond resin according to the second embodiment.

An embodiment (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions or changes of the configuration can be made without departing from the gist of the present invention.

[Embodiment 1]
The method of laying the die bond resin according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of a wafer to be processed in the method of laying the die bond resin according to the first embodiment. FIG. 2 is a perspective view showing a state in which a dividing groove is formed in the wafer shown in FIG. 1 and a protective tape is attached to the surface side. FIG. 3 is a flowchart showing the flow of the method of laying the die bond resin according to the first embodiment.

The method for laying the die-bonding resin according to the first embodiment is the processing method for the wafer 1 shown in FIG. In the first embodiment, the wafer 1 is a disk-shaped semiconductor wafer or an optical device wafer having silicon, sapphire, gallium arsenide, SiC (silicon carbide) or the like as a substrate 2. As shown in FIG. 1, the wafer 1 has a surface 5 in which a device 4 is formed in a plurality of regions partitioned by a plurality of linear scheduled division lines 3 intersecting with each other. Further, in the first embodiment, as shown in FIG. 2, the method of laying the die bond resin according to the first embodiment is carried out in a state where the protective tape 10 which is a protective member is attached to the surface 5 of the wafer 1. To. The protective tape 10 is formed in a disk shape having the same diameter as the wafer 1 and includes a base material layer made of resin and a glue layer to be attached to the wafer 1. In the drawings shown, the base material layer and the glue layer are omitted. Further, in the wafer 1, a division groove 12 for dividing the substrate 2 is formed in each scheduled division line 3, and the wafer 1 is divided into individual device chips 7 along the planned division line 3 and the die bond according to the first embodiment. The method of laying the resin is carried out. The dividing groove 12 is formed by ablation processing using a laser beam or cutting processing using a cutting blade. Alternatively, the dividing groove 12 is formed when the wafer 1 is fractured with the modified layer formed inside the wafer 1 as the fracture starting point by a laser beam. The device chip 7 includes a part of the substrate 2 and the device 4.

The method for laying the die-bonding resin according to the first embodiment is a method for processing a wafer in which the die-bonding resin 13 shown in FIG. 4 or the like is laid on the exposed back surface 6 of the wafer 1. The die-bonding resin 13 is for fixing the device chip 7 to an adhesive destination such as a printed wiring board when the device chip 7 is mounted. In the first embodiment, the die-bonding resin 13 is laid on the back surface 6 of the wafer 1 in a liquid state, and then cured by being irradiated with ultraviolet rays 14 (shown in FIG. 6) which are external stimuli. After the die-bonding resin 13 is cured, it is temporarily softened by being heated by another external means, the device chip 7 is fixed to an adhesive destination such as a printed wiring board, and the resin 13 is cured again after being fixed. In the first embodiment, the die-bonding resin 13 is a Honghow Specialty Chemicals Inc. The product name "HP20VL" or "ST20VL" can be adopted.

As shown in FIG. 3, the die bond resin laying method includes a die bond resin laying step ST1, a curing step ST2, a flattening step ST3, and a sheet peeling step ST4.

(Resin laying step for die bond)
FIG. 4 is a perspective view showing a die bond resin laying step of the die bond resin laying method according to the first embodiment. FIG. 5 is a cross-sectional view of the wafer after the die bond resin laying step of the die bond resin laying method according to the first embodiment.

The die bond resin laying step ST1 is a step of laying a liquid die bond resin 13 that is softened by heating on the back surface 6 of the wafer 1 and cured by irradiation with ultraviolet rays 14. In the first embodiment, in the die bond resin laying step ST1, as shown in FIG. 4, the surface 5 side of the wafer 1 is placed on the holding surface 22 of the holding table 21 of the resin laying device 20 via the protective tape 10. , The resin laying device 20 sucks and holds the wafer 1 on the holding surface 22 of the holding table 21.

In the first embodiment, in the die bond resin laying step ST1, the resin laying device 20 moves the coating nozzle 23 at least once along the first linear direction 24 and moves the holding table 21 to the first, as shown in FIG. The liquid die-bonding resin 13 mixed with the gas pressurized from the coating nozzle 23 while being moved at least once in the second linear direction 25 intersecting (orthogonal in the first embodiment) in the linear direction 24 of the wafer 1. It is sprayed on the back surface 6. The relative moving directions of the coating nozzle 23 and the holding table 21 are not limited to the example shown in FIG. In the first embodiment, in the die bond resin laying step ST1, the resin laying device 20 lays the die bond resin 13 on the entire back surface 6 of the wafer 1 as shown in FIG. As for the method of laying the die bond resin, when the die bond resin 13 is laid on the entire back surface 6 of the wafer 1, the process proceeds to the curing step ST2.

(Curing step)
FIG. 6 is a side view showing a curing step of the method of laying the die bond resin shown in FIG. FIG. 7 is a cross-sectional view of a wafer showing an enlarged VII portion in FIG. 6 after the curing step of the method of laying the die bond resin shown in FIG.

The curing step ST2 is a step of curing the laid resin 13 for die bonding by irradiation with ultraviolet rays 14. In the first embodiment, in the curing step ST2, the wafer 1 is removed from the holding table 21 of the resin laying device 20, and the surface 5 side of the wafer 1 is passed through the protective tape 10 and the ultraviolet irradiation device 30 is shown in FIG. The wafer 1 is sucked and held on the holding surface 32 of the holding table 31 by the ultraviolet irradiation device 30.

In the first embodiment, in the curing step ST2, the ultraviolet irradiation device 30 irradiates the die bond resin 13 with ultraviolet rays 14 from the ultraviolet irradiation unit 33, and is laid on the back surface 6 to cure the die bond resin 13. The ultraviolet irradiation unit 33 of the ultraviolet irradiation device 30 includes a plurality of LEDs 34 (Light Emitting Diodes) that irradiate the ultraviolet 14, and the LED 34 is arranged at a position where the ultraviolet 14 can be irradiated on the entire back surface 6.

In the first embodiment, the ultraviolet irradiation unit 33 of the ultraviolet irradiation device 30 includes a plurality of LEDs 34 that irradiate the ultraviolet 14, but the configuration of the ultraviolet irradiation unit 33 is not limited to that shown in FIG. In the curing step ST2, the ultraviolet irradiation device 30 irradiates the entire die-bonding resin 13 with the ultraviolet rays 14 for a predetermined time during which the entire die-bonding resin 13 can be completely cured, and then stops the irradiation of the ultraviolet rays 14 to completely cure the entire die-bonding resin 13. Since the die-bonding resin 13 laid on the back surface 6 has the dividing groove 12 formed in the wafer 1, the surface tension when the wafer 1 is liquid causes the die-bonding resin 13 to be on the outer edge of the device chip 7 as shown in FIG. The thickness 15 is formed to be thicker than the thickness 16 on the central portion of the device chip 7, and the surface 17 of the die bond resin 13 is uneven. The method of laying the die-bonding resin proceeds to the flattening step ST3 when the entire die-bonding resin 13 laid on the back surface 6 of the wafer 1 is completely cured.

(Flatification step)
FIG. 8 is a perspective view showing a flattening step of the method of laying the die bond resin shown in FIG. FIG. 9 is a cross-sectional view of a wafer showing a flattening step of the method of laying the die bond resin shown in FIG.

In the flattening step ST3, after performing the curing step ST2, the surface 17 of the uneven die-bonding resin 13 is heated, and the surface 17 of the softened die-bonding resin 13 is pressed through the flat sheet 18 to press the surface 17 of the softened die-bonding resin 13 through the flat sheet 18. This is a step of flattening the surface 17 of 13.

In the flattening step ST3, the wafer 1 is removed from the holding table 31 of the ultraviolet irradiation device 30, and the surface 5 side of the wafer 1 is placed on the holding surface 42 of the holding table 41 of the flattening device 40 via the protective tape 10. Then, the flattening device 40 sucks and holds the wafer 1 on the holding surface 42 of the holding table 41.

In the first embodiment, in the flattening step ST3, as shown in FIGS. 8 and 9, the flattening apparatus 40 holds the sheet 18 having a constant thickness 18-1 on the holding table 41. The entire surface 17 of the die-bonding resin 13 on the back surface 6 of the above is covered. The sheet 18 is composed of a base material layer 181 made of a synthetic resin or the like, and in the first embodiment, the base material layer 181 is a sheet made of polyolefin (Polyolefin), but in the present invention, the synthetic resin constituting the sheet 18 Is not limited to polyolefins. For example, the synthetic resin constituting the base material layer 181 of the sheet 18 may be polyethylene terephthalate, vinyl chloride or the like. Further, it is desirable that the thickness 18-1 is, for example, 40 μm or more and has a waist that can maintain a flat shape.

In the first embodiment, in the flattening step ST3, the flattening device 40 heats the die-bonding resin 13 on the back surface 6 of the wafer 1 by the heating unit 43 shown in FIG. 9 embedded in the holding table 41 for die-bonding. The resin 13 is slightly softened. In the present invention, the configuration of the heating unit 43 is not limited to that shown in FIG. In the first embodiment, in the flattening step ST3, the flattening device 40 slightly softens the die-bonding resin 13 and rotates the roller 44 through the sheet 18 to press the surface 17 of the die-bonding resin 13 to flatten it. To become. In the flattening step ST3, the flattening device 40 can flatten the surface 17 by pressing with the roller 44, and slightly softens the die-bonding resin 13 to the extent that the sheet 18 is peeled off from the re-cured die-bonding resin 13. ..

In the first embodiment, the roller 44 is rotatable around the axis 45 and has a columnar appearance. The roller 44 has an axis 45 arranged parallel to the holding surface 42, and is moved in a direction (horizontal direction) orthogonal to the axis 45 while pressing the die bonding resin 13 on the outer peripheral surface, so that the roller 44 moves with the movement. It rotates on the seat 18 around the axis 45. In the flattening step ST3, the flattening device 40 positions the roller 44 on the sheet 18 and presses the roller 44 against the surface 17 of the die bonding resin 13 via the sheet 18 while moving the roller 44 in the horizontal direction. The method of laying the die-bonding resin proceeds to the sheet peeling step ST4 when the roller 44 is moved in the horizontal direction a predetermined number of times while pressing the roller 44 on the die-bonding resin 13 via the sheet 18.

(Sheet peeling step)
FIG. 10 is a cross-sectional view of a wafer or the like after the sheet peeling step of the method of laying the die bond resin shown in FIG. FIG. 11 is a cross-sectional view of a wafer in which the XI portion in FIG. 10 is enlarged and shown.

The sheet peeling step ST4 is a step of stopping the heating of the flattened die-bonding resin 13 and peeling off the adhered sheet 18 and the die-bonding resin 13. In the sheet peeling step ST4, after a predetermined time has elapsed in which the heating by the heating unit 43 of the flattening device 40 is stopped and the die bond resin 13 is cooled and cured again, the sheet is sucked and held on the holding surface 42 of the holding table 41. The sheet 18 is peeled off from the die-bonding resin 13 by moving the sheet 18 with the holding table 41 and the holding table 41 in the vertical direction or in a direction in which the sheet 18 flipped from the end is relatively separated from the wafer 1 in the direction opposite to the wafer 1 along the holding surface 42. do.

Since the die-bonding resin 13 after the sheet peeling step ST4 is flattened by the roller 44 through the sheet 18 while being heated in the flattening step ST3, the thickness on the outer edge portion of the device chip 7 is as shown in FIG. The 15-1 and the thickness 16-1 on the central portion of the device chip 7 are formed equally, and the surface 17 of the die bonding resin 13 is formed flat. The method of laying the die bond resin ends after the sheet peeling step ST4.

In the method of laying the die-bonding resin according to the first embodiment, the die-bonding resin 13 having irregularities on the surface 17 after the curing step ST2 is slightly softened by heating in the flattening step ST3, and then the flat sheet 18 is laid. Press through to flatten. Therefore, in the method of laying the die bond resin, the surface 17 of the die bond resin 13 laid on the device chip 7 can be formed flat, and the unevenness of the surface 17 of the die bond resin 13 on the back surface 6 of the device chip 7 is suppressed. can do. As a result, the method of laying the resin for die bonding can suppress the gas entering between the device chip 7 and the adhesive destination when the device chip 7 is fixed to the adhesive destination, and the entire back surface 6 of the device chip 7 can be suppressed. Has the effect of being able to be completely attached to the adhesive destination.

Further, in the method of laying the die bond resin, since the roller 44 is moved horizontally while being pressed against the die bond resin 13 through the sheet 18, the roller 44 is rotated through the sheet 18 to flatten the die bond resin 13. .. As a result, in the method of laying the die-bonding resin, since the roller 44 that is rotatable around the axis 45 is used in the flattening step ST3, the variation in the thicknesses 15-1 and 16-1 of the die-bonding resin 13 is suppressed. be able to.

Further, in the method of laying the die bond resin, since the sheet 18 is made of polyolefin, the surface 17 of the die bond resin 13 can be formed flat while suppressing the adhesion of the die bond resin 13 to the sheet 18.

[Embodiment 2]
The method of laying the die bond resin according to the second embodiment of the present invention will be described with reference to the drawings. FIG. 12 is a cross-sectional view of a wafer showing a flattening step of the method of laying the die bond resin according to the second embodiment. FIG. 13 is a cross-sectional view of a wafer or the like showing a part of the sheet peeling step of the method for laying the die bond resin according to the second embodiment. In FIGS. 12 and 13, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The method of laying the die bond resin according to the second embodiment is the same as that of the first embodiment except that the flattening step ST3 and the sheet peeling step ST4 are different from the first embodiment.

In the flattening step ST3 of the method for laying the die bond resin according to the second embodiment, as in the first embodiment, the flattening device 40 sucks and holds the wafer 1 on the holding surface 42 of the holding table 41, and then shows in FIG. As described above, the die-bonding resin 13 on the back surface 6 of the wafer 1 in which the sheet 18-2 having a constant thickness 18-1 and having the base material layer 181 and the glue layer 182 is held on the holding table 41. Cover the entire surface 17. In the second embodiment, in the flattening step ST3, the flattening apparatus 40 positions the annular frame 11 having an inner diameter larger than that of the wafer 1 at a position coaxial with the wafer 1 before the sheet 18-2 is placed on the wafer 1. Deploy. In the second embodiment, the sheet 18-2 and the base material layer 181 are formed in a disk shape having a diameter smaller than the outer diameter of the annular frame 11 and a diameter larger than the inner diameter of the annular frame 11, and the glue layer 182 is a base. It is formed on the surface of a portion having a diameter larger than the inner diameter of the annular frame 11 of the material layer 181. In the second embodiment, in the flattening step ST3, the flattening apparatus 40 superimposes the glue layer 182 on the annular frame 11 when the sheet 18-2 is put on the wafer 1, and the base material layer 181 at a portion without the glue layer 182. Is layered on the wafer 1.

In the second embodiment, in the flattening step ST3, the flattening device 40 heats the die-bonding resin 13 on the back surface 6 of the wafer 1 by the heating unit 43 embedded in the holding table 41, and the die-bonding resin 13 is slightly removed. The roller 44 is rotated through the sheet 18 to press the surface 17 of the die-bonding resin 13 through the base material layer 181 where the glue layer 182 is not present to flatten the surface 17 of the die-bonding resin 13, and the base material layer is flattened by the roller 44. The glue layer 182 is pressed against the annular frame 11 via 181 to bond the sheet 18-2 to the annular frame 11. At this time, the sheet 18-2 holds the device chip 7 by the adhesion force or the tack force of the sheet 18-2.

In the sheet peeling step ST4 of the method for laying the die bond resin according to the second embodiment, the heating of the flattened die bond resin 13 by the heating unit 43 is stopped, the wafer 1 is removed from the holding table 41 of the flattening device 40, and the wafer 1 is removed from the holding table 41. As shown in FIG. 13, the back surface 6 side of the wafer 1 is placed on the holding surface 52 of the holding table 51 of the peeling device 50 via the sheet 18-2, and the peeling device 50 is placed on the holding surface 52 of the holding table 51. The wafer 1 is sucked and held.

In the sheet peeling step ST4 of the method for laying the resin for die bonding according to the second embodiment, the peeling device 50 peels the protective tape 10 from the surface 5 side of the wafer 1 instead of the sheet 18-2, and the wafer is peeled off by the sheet 18-2. 1 (that is, the device chip 7) forms a frame unit 19 fixed to the annular frame 11. In the sheet peeling step ST4 of the method of laying the resin for die bonding according to the second embodiment, the frame unit 19 is set in a pickup device (not shown), individual device chips 7 are picked up from the frame unit 19, and the sheets 18-2 are in close contact with each other. And the die bond resin 13 are peeled off.

In the method of laying the die-bonding resin according to the second embodiment, similarly to the first embodiment, the die-bonding resin 13 having irregularities on the surface 17 after the curing step ST2 is slightly softened by heating in the flattening step ST3. After that, since it is pressed through the flat sheet 18 to be flattened, the unevenness of the front surface 17 of the die bonding resin 13 on the back surface 6 of the device chip 7 can be suppressed.

The present invention is not limited to the above embodiment. That is, it can be variously modified and carried out within a range that does not deviate from the gist of the present invention.

1 Wafer 2 Substrate 3 Scheduled division line 4 Device 5 Front side 6 Back side 7 Device chip 10 Protective tape (protective member)
13 Diebond resin 14 Ultraviolet rays 17 Surface 18,18-2 Sheet 44 Roller ST1 Diebond resin laying step ST2 Curing step ST3 Flattening step ST4 Sheet peeling step

Claims (3)

A wafer in which a protective member is attached to a surface on which a device is formed in a plurality of regions divided by a plurality of planned division lines, and the wafer is divided into individual device chips along the planned division line. It is a method of laying the resin for die bond by laying the resin for die bond on the back surface.
A die bond resin laying step for laying a liquid die bond resin that is softened by heat and cured by irradiation with ultraviolet rays on the back surface of the wafer.
A curing step of curing the laid resin for die bonding by irradiation with ultraviolet rays,
After performing the curing step, the surface of the uneven die-bonding resin is heated, the softened surface of the die-bonding resin is pressed through a flat sheet, and the flattening step of flattening the die-bonding resin is performed. ,
A method for laying a die-bonding resin, comprising: stopping heating of the flattened die-bonding resin and a sheet peeling step for peeling off the adhered sheet and the die-bonding resin. The method for laying a die bond resin according to claim 1, wherein in the flattening step, a roller is rotated through the sheet to press the surface of the die bond resin to flatten the surface. The method for laying a die bond resin according to claim 1 or 2, wherein the sheet is a sheet made of polyolefin.

Images