Resin sealing process for semiconductor chips

Abstract

A resin sealing method for a plurality of semiconductor chips. The resin sealing method includes a die-holding line attachment step of attaching a die-holding line to a support substrate through an adhesive ring, a semiconductor die-holding step of attaching the front side of each semiconductor chip to an adhesive layer forming the die-holding line in a region corresponding to the interior of the adhesive ring, a resin sealing step of sealing all of the semiconductor chips with a molding resin, a support substrate removal step of removing the support substrate from the die-holding line on which the semiconductor chips are mounted and sealed with the molding resin, and a die-holding line peeling step of peeling the die-holding line from the front side of each semiconductor chip sealed with the molding resin.

Description

Background of the inventionField of the invention

[0001] The present invention relates to a resin sealing method for a plurality of semiconductor chips with a resin. Description of the state of the art

[0002] For example, Japanese Patent Application Laid-Open No. JP-08-78566 A discloses a manufacturing method for an area package type semiconductor unit. The area package type semiconductor unit includes a substrate, such as a resin substrate formed of a glass fiber-based epoxy resin, semiconductor chips mounted on the front side of the substrate, external electrodes provided on the back side of the substrate to be arranged in a grid-like manner, and a sealing member, such as a molding resin, for sealing the semiconductor chips on the front side of the substrate.

[0003] US 2011 / 0 143 552 A1 relates to a heat-resistant film for producing semiconductors.

[0004] US 2002 / 0 004 288 A1 concerns a manufacturing method of LSI chips.

[0005] JP 2011- 236 59 A relates to a wafer processing method.

[0006] US 2005 / 0 070 072 A1 relates to a method for processing a wafer. Summary of the invention

[0007] However, when sealing the semiconductor chips with the molding resin, the semiconductor chips are attached to a steel support substrate by a thermally releasable tape, and the molding resin is then applied to the support substrate to seal the semiconductor chips. Consequently, it takes a long time to remove the support substrate from the molding resin after sealing the semiconductor chips with the molding resin. Furthermore, adhesive material of the thermally releasable tape may remain on the surface of each semiconductor chip after removing the support substrate.

[0008] It is therefore an object of the present invention to provide a resin sealing method for a plurality of semiconductor chips which can simplify the removal of the support substrate when sealing the semiconductor chips with the molding resin, thereby shortening the manufacturing time.

[0009] According to one aspect of the present invention, there is provided a resin sealing method for a plurality of semiconductor chips, including: a die-holding line attaching step of attaching a die-holding line to a plate-like support substrate through an adhesive ring, the die-holding line having a base surface and an adhesive layer formed on the front surface of the base surface, the adhesive ring having an outer dimension equal to that of the die-holding line, and the support substrate having an outer dimension larger than that of the die-holding line; a semiconductor chip attaching step of attaching the front surface of each semiconductor chip to the adhesive layer of the die-holding line in a region corresponding to the interior of the adhesive ring after performing the die-holding line attaching step; a resin sealing step of sealing all of the semiconductor chips with a molding resin after performing the semiconductor chip attaching step;a carrier substrate removal step of removing an adhesive force to the die-holding sheet after performing the resin sealing step, thereby removing the carrier substrate from the die-holding sheet on which the semiconductor chips are mounted and sealed with the molding resin; and a die-holding sheet peeling step of peeling the die-holding sheet from the front side of each semiconductor chip sealed with the molding resin after performing the carrier substrate removal step.

[0010] Preferably, the resin sealing method further includes a grinding step of grinding the molding resin in the state where the chip holding sheet is held on a holding table after performing the carrier substrate removing step, thereby reducing the thickness of the molding resin until each semiconductor chip is exposed.

[0011] Preferably, the carrier substrate has an annular groove with a shape corresponding to the shape of the adhesive ring on the front side of the carrier substrate, and the annular groove is filled with the adhesive ring (12). As a modification, the adhesive ring is attached to the back side of the base surface of the chip holding track opposite the adhesive layer along the outer circumference of the base surface.

[0012] Preferably, the adhesive ring is formed of an ultraviolet-curable adhesive, and the carrier substrate removing step includes the step of applying ultraviolet light to the adhesive ring to cure the adhesive ring, thereby removing the adhesive force of the adhesive ring.

[0013] Preferably, the carrier substrate removing step includes the step of cutting the chip holding track along the inner circumference of the adhesive ring using a cutting blade, thereby removing the adhesive force of the adhesive ring.

[0014] According to the resin sealing method of the present invention, the die-holding line is fixed to the support substrate by the adhesive ring, and the plurality of semiconductor chips are fixed to the die-holding line and sealed with the molding resin. Consequently, the molding resin and the die-holding line can be separated from the support substrate by simply removing the adhesive force of the adhesive ring. Since the area occupied by the adhesive ring on the support substrate is small, the molding resin and the die-holding line can be easily separated from the support substrate. By studying the following description and appended claims with reference to the accompanying drawings which show a preferred embodiment of the invention, the above and other objects, features and advantages of the present invention and the manner of achieving them will become apparent, and the invention itself can be best understood. Short description of the drawings Fig. 1A is a perspective view of a semiconductor device obtained by a preferred embodiment of the resin sealing method according to the present invention; Fig. 1B is a sectional view of the Fig. 1A shown semiconductor unit; Fig. 2A is a perspective view showing a chip holding line attaching step in this preferred embodiment; Fig. 2B is a sectional view of a chip holding track, a carrier substrate and an adhesive ring shown in Fig. 2A; Fig. 3 is a sectional view of the chip holding trace fixed to the support substrate by the adhesive ring through the chip holding trace fixing step; Fig. 4 is a sectional view showing a semiconductor chip mounting step in this preferred embodiment; Fig. Fig. 5 is a sectional view showing a resin sealing step in this preferred embodiment; Fig. 6 is a sectional view showing a carrier substrate removing step in this preferred embodiment; Fig. Fig. 7 is a sectional view showing a grinding step in this preferred embodiment; Fig. 8A and Fig. 8B are sectional views showing a chip holding line peeling step in this preferred embodiment; Fig. 9 is a sectional view showing a forming step of a rewiring layer in this preferred embodiment; Fig. 10 is a sectional view showing a modification of the chip holding line attaching step; Fig. 11 is a sectional view showing a modification of the carrier substrate removing step; and Fig. 12 is a sectional view showing an edge processing step in the present invention. Detailed description of the preferred embodiment

[0015] A preferred embodiment of the present invention will now be described in detail with reference to the drawings. The present invention is not limited to this preferred embodiment. Furthermore, the components used in this preferred embodiment may include those easily adopted by those skilled in the art or may be substantially the same elements as those known in the art. Furthermore, the arrangements described below may be appropriately combined. Furthermore, the arrangements may be variously omitted, substituted, or changed without departing from the scope of the present invention.

[0016] The resin sealing method according to this present embodiment is a Fig. 1B shown method of sealing several semiconductor chips 1 with a molding resin 2 in order to form a Fig. 1A and Fig. 1B shown semiconductor unit 3 (corresponding to a package). As in Fig. 1A and Fig. As shown in FIG. 1B, the semiconductor device 3 obtained by the resin sealing method according to the preferred embodiment is a disk-shaped object, and includes the plurality of semiconductor chips and the molding resin 2 covering the plurality of semiconductor chips 1 except for their patterned surfaces 1a (corresponding to the front surfaces) where terminals are formed. Each semiconductor chip 1 is obtained by forming, for example, an IC or LSI such as a memory, logic, gate array, custom array, and power transistor on a semiconductor wafer made of Si or GaAs. As described above, terminals are formed on the patterned surface 1a of each semiconductor chip 1. Further, a wiring layer 4 constituted by bumps connected to the terminals is formed on the patterned surface 1a of each semiconductor chip 1.The molding resin 2 is formed of a resin that is moldable by a molding process at a predetermined molding temperature.

[0017] The resin sealing method according to this preferred embodiment, used as in Fig. 2A and Fig. 2B, a carrier substrate 10 and a chip holding track 11. The carrier substrate 10 is formed, for example, from metal (e.g., iron) or resin. As shown in Fig. 2A and Fig. 2B, the support substrate 10 is a plate member whose outer dimension is larger than the die-holding track 11. Specifically, the support substrate 10 is a circular plate member, and the die-holding track 11 is a circular track member, the diameter of the support substrate 10 being larger than that of the die-holding track 11. To accommodate an adhesive ring 12, an annular groove 13 is formed on the front side (upper surface) 10a of the support substrate 10 along its entire circumference. The annular groove 13 has an outer dimension equal to that of the die-holding track 11. The annular groove 13 is formed only on the outer peripheral portion on the front side 10a of the support substrate 10. Specifically, the annular groove 13 is an annular groove having an outer diameter equal to the diameter of the die-holding track 11. The adhesive ring 12 received in the annular groove 13 is formed of an ordinary adhesive or an ultraviolet-curable adhesive.

[0018] As in Fig. 2A and Fig. As shown in Figure 2B, the die holding sheet 11 consists of a base surface 15 and an adhesive layer 14 formed on the front surface (upper surface) of the base surface 15 for mounting semiconductor chips 1 thereon. The adhesive layer 14 is formed by applying an adhesive to the entire surface of the front surface of the base surface. The adhesive layer is formed of a photo-curable adhesive that can be cured by ultraviolet light or visible light. Specifically, the adhesive layer 14 is formed of an ultraviolet-curable adhesive that can be cured by ultraviolet light. The base surface 15 is formed of a transparent or translucent synthetic resin capable of transmitting ultraviolet light or visible light. Specifically, the base surface 15 is formed of a synthetic resin capable of transmitting ultraviolet light.As described above, the chip holding track 11 in this preferred embodiment is a circular track element.

[0019] The resin sealing method according to this preferred embodiment is carried out in the following manner. First, the adhesive ring 12 is filled into the annular groove 13 of the support substrate 10 such that the upper surface of the adhesive ring 12 is flush with the front side 10a of the support substrate 10. Thereafter, the Fig. 2A and Fig. 2B is performed such that the chip holding line 11 is attached to the support substrate by the adhesive ring 12. Specifically, the base surface 15 of the chip holding line 11 is attached to the front surface 10a of the support substrate so that the chip holding line 11 is aligned with the support substrate 10. Thus, the outer peripheral portion of the chip holding line is placed on the adhesive ring filled in the annular groove. Fig. 3 shows a state obtained by performing the chip holding line attaching step. As in Fig. 3, the chip holding track 11 is fixed by the adhesive ring 12 to the support substrate 10 in a state that the base surface 15 of the chip holding track 11 is in contact with the front surface 10a of the support substrate 10. Since the outer diameter of the adhesive ring 12 is equal to the diameter of the chip holding track 10, only the outer peripheral portion of the base surface 15 of the chip holding track 11 is fixed to the support substrate 10 by the adhesive ring. After performing the above-mentioned chip holding track fixing step, the Fig. 4 is carried out such that the structured surface 1a of each semiconductor chip 1 is attached to the adhesive layer 14 of the chip holding track 11 in a region corresponding to the interior of the adhesive ring 12.

[0020] After performing the above-mentioned semiconductor chip attaching step, as shown in Fig. 5, a resin sealing step is performed such that all of the plurality of semiconductor chips 1 are sealed with the molding resin 2. Specifically, the molding resin 2 is formed on the die holding line 11 in a region corresponding to the inside of the adhesive ring 12 so as to completely cover all of the plurality of semiconductor chips 1 through a molding process. Consequently, all of the plurality of semiconductor chips 1 attached to the die holding line 11 are sealed with the molding resin 2 in a region corresponding to the inside of the adhesive ring 12.

[0021] After performing the above-mentioned resin sealing step, as in Fig. 6, a carrier substrate removing step is performed such that the die holding sheet 11 is cut along the entire inner circumference of the adhesive ring 12 using a cutting blade 20. Consequently, an adhesive force of the adhesive ring 12 to the die holding sheet 11 is removed, thereby removing the carrier substrate 10 together with the adhesive ring 12 from the die holding sheet 11 on which the plurality of semiconductor chips 1 are mounted and sealed with the molding resin 2.

[0022] After performing the above-mentioned carrier substrate removal step, a grinding step as in Fig. 7 in the following manner. The mold resin 2, which seals the plurality of semiconductor chips 1, is transferred together with the chip holding track 11 to a holding table 22 of a Fig. 7 using a transport device (not shown). Therefore, the plurality of semiconductor chips 1, which are attached to the chip holding sheet 11 and sealed with the molding resin 2, are mounted on the holding table 22 in the state where the chip holding sheet 11 is in contact with the holding table 22 and the molding resin 2 is exposed. In this state, the chip holding sheet 11 is held on the holding table 22 under suction, and the molding resin 2 is ground using grinding members 23 constituting the grinding device 21, thereby reducing the thickness of the molding resin 2 until the plurality of semiconductor chips 1 are exposed. As shown in Fig. 7, the grinding apparatus 21 used in this grinding step mainly includes the holding table 22 for holding the molding resin 2 by the die holding sheet 11, and the grinding members 23 for grinding the molding resin 2 held on the holding table 22, thereby reducing the thickness of the molding resin 2 to a final thickness. The holding table 22 has a circular holding surface 22a formed of a porous ceramic material or the like. The holding surface 22a is connected to a vacuum source (not shown) through a vacuum line (not shown), whereby the molding resin 2 is held on the holding surface 22a by the die holding sheet 11 under suction. Further, the holding table is rotatable about its axis by a rotary motion drive source (not shown).When grinding the mold resin 2, the holding table 22 holding the mold resin 2 is rotated by the rotational motion drive source, and the grinding members 23 are equally rotated in the same direction as the rotational direction of the holding table 22.

[0023] After performing the above-mentioned grinding step, a chip holding track peeling step is performed as in Fig. 8A and Fig. 8B shown in the following manner. As shown in Fig. As shown in Fig. 8A, the molding resin 2 and the die-holding sheet 11 are transported to ultraviolet application devices 30 to expose the die-holding sheet 11 to a plurality of ultraviolet lamps 31 constituting the ultraviolet application device 30. In this state, ultraviolet light V is applied to the adhesive layer 14 of the die-holding sheet 11 from the ultraviolet lamps 31 of the ultraviolet application device 30 through the base surface of the die-holding sheet 11. As a result, the adhesive layer 14 adhered to the patterned surface 1a of each semiconductor chip 1 is cured by the ultraviolet light V, thereby reducing an adhesive force of the adhesive layer 14 of the die-holding sheet 11. Thereafter, as shown in Fig. 8B, the chip holding line 11 is peeled off from the patterned surface 1a of each semiconductor chip 1 sealed with the molding resin 2.

[0024] After performing the above-mentioned chip holding line peeling step, a rewiring layer forming step as shown in Fig. 9, is designed such that bumps or the like are connected to the terminals on the patterned surface 1a of each semiconductor chip 1 sealed with the molding resin 2, thereby forming the wiring layer 4 on the patterned surface 1a. In this way, the semiconductor unit 3 described above with reference to Fig. 1A and Fig. 1B was obtained.

[0025] In the resin sealing method according to this preferred embodiment described above, the die-holding sheet 11 is fixed to the support substrate 10 by the adhesive ring 12, and the plurality of semiconductor chips 1 are next fixed to the die-holding sheet 11. After that, the plurality of semiconductor chips 1 are sealed with the molding resin 2. Thus, simply by removing the adhesive force of the adhesive ring 12, the molding resin and the die-holding sheet 11 can be removed from the support substrate 10. As a result, the manufacturing time can be shortened, and likewise, the work efficiency in manufacturing the semiconductor unit 3 can be improved. Further, in the support substrate removing step, the cutting blade 20 is used to cut the die-holding sheet 11 along the inner circumference of the adhesive ring 12. Thus, the die-holding sheet 11 can be removed from the support substrate 10 without leaving the adhesive ring 12 on the die-holding sheet 11.Consequently, the subsequent grinding step can be performed in the state where the die-holding sheet 11 attached to the mold resin 2 is held on the holding table 22 of the grinding device 21. In this state, the mold resin 2 is ground by the grinding elements 23 of the grinding device 21. Consequently, the die-holding sheet 11 can be used as a protective tape for protecting the patterned surface 1a of each semiconductor chip 1 in the grinding step. This means that when performing the grinding step, the mold resin 2 does not need to be transferred to a dedicated protective tape, thereby further shortening the manufacturing time and further improving the work efficiency in manufacturing the semiconductor unit 3. Furthermore, the adhesive layer 14 of the die-holding sheet 11 is formed of an ultraviolet-curable adhesive, and in the die-holding sheet peeling step, the adhesive layer 14 is cured by applying ultraviolet light V.Consequently, it is possible to prevent the adhesive layer 14 of the chip-holding track 11 peeled off in the chip-holding track peeling step from remaining on the patterned surface 1a of each semiconductor chip. In the event that even a portion of the adhesive ring 12 remains on the base surface 15 of the chip-holding track after the carrier substrate removal step, the adhesive ring 12 remaining on the base surface 15 of the chip-holding track 11 is preferably removed before the grinding step.

[0026] While the adhesive ring 12 is filled into the annular groove 13 formed on the front side 10a of the support substrate 10 in this preferred embodiment, the adhesive ring 12 may be provisionally attached to the back side (lower surface) of the base surface 15 opposite the adhesive layer 14 along the entire outer circumference of the base surface 15, as shown in Fig. 10. That is, Fig. Fig. 10 is a sectional view showing a modification of the chip holding line attaching step. In this modification, the chip holding line 11 includes the base 15 and the adhesive layer 14, and the adhesive ring 12 is attached to the back of the base 15 opposite the adhesive layer 14 along the entire outer periphery of the base 15. According to this Fig. 10, the adhesive ring 12 does not need to be filled into the annular groove 13 formed on the support substrate 10 before the chip holding line attaching step is carried out, so that the chip holding line attaching step can be easily carried out by simply attaching the chip holding line 11 to the support substrate 10 through the adhesive ring 12.

[0027] In this preferred embodiment, the adhesive ring 12, as shown in Fig. 11, be formed from an ultraviolet-curable adhesive. That is, Fig. 11 is a sectional view showing a modification of the carrier substrate removal step. In this modification, ultraviolet lamps 31 are used to apply ultraviolet light through the die-holding trace 11 to the adhesive ring 12, thereby curing the adhesive ring 12 to eliminate the adhesive force of the adhesive ring 12. As a result, the die-holding trace 11 can be separated from the carrier substrate 10. In this case, the adhesive ring 12 may be formed of two layers, i.e., an ultraviolet-curable adhesive layer attached to the base surface 15 of the die-holding trace and a non-ultraviolet-curable layer attached to the bottom of the ring groove 13. In the case where the adhesive ring 12 is composed of these two layers, the adhesive force of the ultraviolet-curable adhesive layer is eliminated by applying the ultraviolet light, but the adhesive force of the non-ultraviolet-curable layer is maintained regardless of the application of the ultraviolet light.Consequently, when the die holding line 11 is removed from the support substrate 10 after applying the ultraviolet light to the die holding line 12, the adhesive ring 12 can be removed from the base surface 15 of the die holding line 11 in the state where the ultraviolet-curable adhesive layer is attached to the non-ultraviolet-curable adhesive layer.

[0028] Furthermore, in this preferred embodiment, after the resin sealing step and before or after the carrier substrate removing step, a Fig. 12 shown edge processing step must be carried out. That is, Fig.12 is a sectional view showing an edge processing step according to a modification of this preferred embodiment, in which the edge processing step is performed after the support substrate removal step and before the grinding step. In this edge processing step, a cutting blade 40 is used to cut the outer peripheral edge of the molding resin 2, thereby removing burrs of the molding resin 2. Consequently, damage to the conveying device caused by the burrs when conveying the molding resin 2 with the semiconductor chips 1 and the die holding sheet 11 can be prevented.

[0029] Furthermore, while in this preferred embodiment, the shapes of the support substrate 10 and the die-holding line are circular, and the shape of the adhesive ring 12 is also circular, the shapes of these devices are not limited in the present invention. For example, if the shape of the die-holding line 11 is quadrangular, the shape of the adhesive ring 12 may be made quadrangular accordingly. Therefore, the shapes of the support substrate 10 and the die-holding line 11 may be made in various shapes, such as a rectangular shape, and the shape of the adhesive ring 12 may be made in various ring shapes, such as a rectangular ring shape. Furthermore, the application of the resin sealing method of the present invention is not limited to a semiconductor unit 3 as a package, but the present invention is applicable to semiconductor chips to form any package having various arrangements.

Claims

[1] Resin sealing method for multiple semiconductor chips (1), comprising: a chip holding track attaching step of attaching a chip holding track (11) to a plate-like support substrate (10) by an adhesive ring (12), the chip holding track (11) having a base surface (15) and an adhesive layer (14) formed on a front side of the base surface (15), the adhesive ring (12) having an outer dimension equal to that of the chip holding track (11), and the support substrate (10) having an outer dimension larger than that of the chip holding track (11); a semiconductor chip attaching step of attaching a front side of each semiconductor chip (1) to the adhesive layer (14) of the chip holding track (11), in an area corresponding to the interior of the adhesive ring (12), after performing the chip holding track attaching step; a resin sealing step of sealing all of the semiconductor chips (1) with a molding resin (2) after performing the semiconductor chip mounting step; a carrier substrate removing step of removing an adhesive force of the adhesive ring (12) to the chip holding track (11) after performing the resin sealing step, thereby removing the carrier substrate (10) from the chip holding track (11) to which the semiconductor chips (1) are attached and sealed with the molding resin (2); and a chip holding sheet peeling step of peeling the chip holding sheet (11) from the front side of each semiconductor chip (1) sealed with the molding resin (2) after performing the carrier substrate removing step. [2] The resin sealing method according to claim 1, further comprising, after performing the support substrate removing step, a grinding step of grinding the molding resin (2) in the state where the chip holding sheet (11) is held on a holding table, thereby reducing the thickness of the molding resin (2) until each semiconductor chip (1) is exposed. [3] The resin sealing method according to claim 1, wherein the support substrate (11) has an annular groove (13) having a shape corresponding to the shape of the adhesive ring (12), and wherein the annular groove (13) is filled with the adhesive ring (12). [4] The resin sealing method according to claim 1, wherein the adhesive ring (12) is attached to a back side of the base surface (15) of the chip holding sheet (11) opposite to the adhesive layer (14) along the outer periphery of the base surface (15). [5] The resin sealing method according to claim 1, wherein the adhesive ring (12) is formed of an ultraviolet-curable adhesive, and the carrier substrate removing step comprises the step of applying ultraviolet light (V) to the adhesive ring (12) to cure the adhesive ring (12), thereby eliminating the adhesive force of the adhesive ring (12). [6] The resin sealing method according to claim 1, wherein the carrier substrate removing step comprises the step of cutting the chip holding sheet (11) along the inner circumference of the adhesive ring (12) using a cutting blade (20), thereby eliminating the adhesive force of the adhesive ring (12).

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