JP2024119587A - Manufacturing method of resin-sealed substrate - Google Patents

Abstract

To provide a resin-sealed substrate manufacturing method that in exposing a head of a resin-sealed chip using a grinding device, inhibits a load of grinding from increasing as compared with conventional methods.SOLUTION: A resin-sealed substrate manufacturing method according to one aspect of the invention includes: a chip arrangement step of arranging a chip on a top face of a substrate; a damage layer formation step of forming a damage layer on the top face of the substrate before or after the chip arrangement step; a sealing step of sealing the chip by fixing, to the top face of the substrate, the chip and resin integrated by coating at least part of the top face of the substrate and a side face and the top face of the chip with the resin; and a grinding step of forming a resin-sealed substrate by exposing the top face of the chip from the resin by using a grinding wheel to grind and remove a part above the chip, of the resin. The grinding step grinds the damage layer together with the resin.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing a resin-sealed substrate.

In the manufacturing process of semiconductor devices, a workpiece, which consists of a large number of chips arranged on the surface of a substrate, is thinned by grinding the back side of the substrate using a grinding device to produce a semiconductor device of the desired thickness. In addition, with the recent demand for thinner semiconductor devices, there is a trend for workpieces to be processed even thinner than before.

Generally, the grinding of a workpiece is carried out while measuring its thickness. An example of a grinding device that grinds a workpiece in this manner is described in Patent Document 1. Patent Document 1 discloses a grinding device that accurately measures the thickness of a workpiece, a semiconductor wafer, while contacting the top surface of the workpiece with a measuring probe, and grinds the semiconductor wafer to the desired thickness.

JP 2000-6018 A

For example, when grinding a workpiece in which a silicon (Si) post is sealed in resin to expose the Si post, the grinding device grinds and removes the resin covering the Si post. However, in this type of grinding process, the material being ground by the grinding device changes from resin to resin and Si, and the grinding load increases at this time. As a result, the grinding device may enter an abnormal state, issue an alarm, and stop grinding the workpiece.

The object of the present invention is therefore to provide a method for manufacturing a resin-sealed substrate that suppresses an increase in the grinding load compared to conventional methods when exposing the head of a resin-sealed chip using a grinding device.

According to one aspect of the present invention, there is provided a method for manufacturing a resin-sealed substrate comprising a substrate, a chip provided on an upper surface of the substrate, and a resin covering the chip, the method including: a chip placement step for placing the chip on the upper surface of the substrate; a damage layer formation step for forming a damage layer on the upper surface of the chip before or after the chip placement step; a sealing step for covering at least a portion of the upper surface of the substrate and the side and upper surface of the chip with the resin, thereby integrating the chip and the resin and fixing them to the upper surface of the substrate and sealing the chip; and a grinding step for removing a portion of the resin above the chip with a grinding wheel to expose the upper surface of the chip from the resin and form the resin-sealed substrate, and in the grinding step, the damage layer is ground together with the resin.

Preferably, in the chip placement step, multiple chips of different thicknesses are placed on the upper surface of the substrate.

Preferably, in the damage layer forming step, the damage layer is formed on the upper surface of the chip by irradiating the upper surface of the chip with a laser beam having a wavelength that can be absorbed by the chip.

Preferably, in the damage layer forming step, the damage layer is formed on the upper surface of the chip by grinding the upper surface of the chip with a grinding wheel.

In a method for manufacturing a resin-encapsulated substrate according to one aspect of the present invention, a damage layer is formed on the top surface of the chip to be exposed. When the top surface of the chip is exposed, the damage layer is ground away, accelerating wear of the grinding wheel. This makes it possible to keep the condition of the grinding wheel in good condition, and suppresses an increase in the grinding load.

In addition, if the height of the exposed chips is varied, the timing of exposure will differ for each chip, allowing the wear of the grinding wheel to be promoted at multiple different times.

FIG. 1 is a perspective view that illustrates a grinding device used in the first embodiment. FIG. 2 is a flow diagram showing the method for manufacturing the resin-encapsulated substrate according to the first embodiment. 3(a) is a cross-sectional view showing the state of the substrate etc. at the chip placement step of FIG. 2, FIG. 3(b) is a cross-sectional view showing the state of the substrate etc. at the damage layer formation step of FIG. 2, FIG. 3(c) is a cross-sectional view showing the state of the substrate etc. at the sealing step of FIG. 2, and FIG. 3(d) is a cross-sectional view showing the state of the substrate etc. at the grinding step of FIG. 2. FIG. 4 is an enlarged cross-sectional view of the substrate, the chip, and the damaged layer shown in FIG. FIG. 5 is a cross-sectional view that illustrates a state in which the resin of the resin-sealed substrate illustrated in FIG. FIG. 6 is a cross-sectional view of a portion of FIG. FIG. 7 is a cross-sectional view of a resin-encapsulated substrate according to the second embodiment. FIG. 8 is a cross-sectional view that typically shows a state in which the resin of the resin-sealed substrate shown in FIG. 7 is being ground away.

The first embodiment of the present invention will be described below with reference to the attached drawings. FIG. 1 is a perspective view showing a grinding device 2 used in the first embodiment. In FIG. 1, some of the elements constituting the grinding device 2 are expressed as functional blocks. In addition, the X-axis (first axis), Y-axis (second axis), and Z-axis (third axis) used in the following description are perpendicular to each other.

As shown in FIG. 1, the grinding device 2 has a base 4 that supports various elements that make up the grinding device 2. A long opening 4a is formed on the top surface of the base 4 in a direction roughly parallel to the X-axis (front-rear direction). A ball screw type X-axis movement mechanism 6 is disposed within the opening 4a. The X-axis movement mechanism 6 includes a motor (not shown) connected to the ball screw and a moving table (not shown), and moves the moving table back and forth along the X-axis.

The top of the moving table is covered by a table cover 8. In addition, bellows-shaped dust-proof and drip-proof covers 10 that can expand and contract in response to the movement of the moving table (table cover 8) are attached to the front and rear of the table cover 8. A chuck table 12 that is configured to hold a plate-shaped substrate 11 used in the manufacture of resin-encapsulated substrates is arranged above the moving table in a manner that is partially exposed from the table cover 8.

The substrate 11 is, for example, a disk-shaped wafer made of a semiconductor material such as silicon. That is, the substrate 11 has a circular surface (top) 11a and a circular back surface (bottom) 11b opposite the surface 11a. The surface 11a side of the substrate 11 is divided into a number of small regions by a number of intersecting streets (planned division lines), and devices such as integrated circuits (ICs) are formed in each small region.

When manufacturing a resin-sealed substrate using this substrate 11, as described below, chips 60 are placed in small regions on the surface 11a of the substrate 11 that correspond to each device (see FIG. 3). Then, the entirety of each chip 60 and at least a portion of the surface 11a of the substrate 11 are covered with resin 64. In other words, each chip 60 is sealed with this resin 64. The grinding device 2 of this embodiment is used, for example, when exposing the top surface of the chip 60 sealed with resin 64 in the manufacturing process of this resin-sealed substrate.

In addition, in this embodiment, a disk-shaped wafer made of a semiconductor material such as silicon is used as the substrate 11, but the material, shape, structure, size, etc. of the substrate 11 are not limited to this embodiment. For example, a substrate made of other materials such as semiconductors, ceramics, resins, metals, etc. may be used as the substrate 11. Similarly, the type, number, shape, structure, size, arrangement, etc. of the devices are not limited to the above embodiment. The substrate 11 does not need to have any devices formed thereon.

The chuck table 12 is connected to a rotary drive source (not shown) such as a motor, and rotates around a rotation axis parallel to the Z axis or a rotation axis slightly tilted relative to the Z axis. A portion of the upper surface 12a of the chuck table 12 is made of, for example, a porous material, and a portion of the upper surface 12a serves as a holding surface that holds the back surface 11b side of the substrate 11, the front surface 11a side of which is coated with resin. In other words, the chuck table 12 has a holding surface on the upper portion that holds the substrate 11.

The holding surface of the chuck table 12 is connected to a suction source (not shown) such as an ejector capable of generating negative pressure via a suction path (not shown) formed inside the chuck table 12. The back surface 11b of the substrate 11 brought into the chuck table 12 is sucked in by the negative pressure of the suction source acting on the holding surface. In this way, the chuck table 12 holds the substrate 11 by sucking in the back surface 11b of the substrate 11, the front surface 11a of which is covered with resin, with the holding surface.

When the moving table is moved back and forth along the X-axis by the above-mentioned X-axis moving mechanism 6, the chuck table 12 also moves back and forth along the X-axis. More specifically, the X-axis moving mechanism 6 moves the chuck table 12, for example, between a load/unload area in front where the substrate 11 is loaded onto the chuck table 12, and a grinding area behind the load/unload area.

A columnar support structure 14 is provided behind the grinding area (i.e., behind the X-axis movement mechanism 6). A Z-axis movement mechanism 16 is disposed on the front side of the support structure 14. The Z-axis movement mechanism 16 has a pair of guide rails 18 that are long in a direction (up and down direction) roughly parallel to the Z axis, and a moving plate 20 is attached to the pair of guide rails 18 in a manner that allows it to slide.

A nut portion (not shown) that constitutes a ball screw is provided on the rear side of the moving plate 20, and a screw shaft 22 that is roughly parallel to the Z axis is connected to this nut portion in a rotatable manner. A motor 24 or the like is connected to one end of the screw shaft 22. By rotating the screw shaft 22 by the motor 24 or the like, the moving plate 20 moves up and down along the guide rail 18.

A support 26 is provided on the front surface of the moving plate 20. A grinding unit 28 capable of grinding the resin coating the front surface 11a side of the substrate 11 held by the chuck table 12 in the grinding area is supported on this support 26. The grinding unit 28 includes a spindle housing 30 fixed to the support 26. The spindle housing 30 contains a spindle 32 whose rotation axis is parallel to the Z axis or slightly inclined to the Z axis, in a manner that allows it to rotate around its axis.

The lower end of the spindle 32 is exposed from the lower end surface of the spindle housing 30, and a disk-shaped mount 34 is fixed to the lower end of the spindle 32. For example, the outer edge of the mount 34 is provided with multiple holes (not shown) that penetrate the mount 34 in the thickness direction, and a bolt 36 is inserted into each hole.

The grinding wheel 38 is fixed to the underside of the mount 34 by the bolts 36 described above. In other words, the grinding wheel 38 is attached to the spindle 32 via the mount 34, etc. The spindle housing 30 also contains a motor (not shown) etc. that is connected to the upper end side of the spindle 32. The grinding wheel 38 rotates together with the spindle 32 due to the power of this motor etc.

The underside of the wheel base 40 has an annular groove (not shown), in which a number of grinding wheels 42, each of which has abrasive grains such as diamond dispersed in a binder such as vitrified or resinoid, are arranged along the circumferential direction of the wheel base 40. In other words, the grinding wheels 42 are arranged on the underside of the wheel base 40. Each grinding wheel 42 is fixed to the wheel base 40 by an adhesive or the like. The size of the abrasive grains and the type of binder are appropriately set according to the quality required for the resin-sealed substrate obtained by grinding.

A controller (control unit) 50 is connected to each element of the grinding device 2. This controller 50 is configured, for example, by a computer including a processing device 52 and a storage device 54, and controls the operation of each element of the grinding device 2 described above so that the resin covering the substrate 11 is appropriately ground.

The processing device 52 is typically a CPU (Central Processing Unit) and performs various processes necessary to control the above-mentioned elements. The storage device 54 includes, for example, a main storage device such as a DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a hard disk drive or flash memory. The functions of the controller 50 are realized, for example, by the processing device 52 operating in accordance with a program stored in the storage device 54.

An input device 56 is connected to the controller 50. The input device 56 is, for example, a touch screen, and is used to input instructions from the operator to the controller 50. This touch screen also serves as a display device that displays information output from the controller 50. Note that a keyboard, mouse, etc. may also be used as the input device 56.

A part of the storage device 54, which includes a non-transitory recording medium that can be read by a computer or the like, stores a program for causing the processing device 52 to execute a series of procedures required for grinding the resin that covers the substrate 11. The processing device 52 performs various procedures required for grinding the resin of the resin-sealed substrate in accordance with this program.

Next, the processing procedure for manufacturing a resin-sealed substrate using the substrate 11 will be described. FIG. 2 is a flow diagram showing the manufacturing method for a resin-sealed substrate according to the first embodiment, and FIGS. 3(a), 3(b), 3(c), and 3(d) are cross-sectional views showing the state of the substrate 11 and other components at each step in FIG. 2. As shown in FIG. 2, the manufacturing method for a resin-sealed substrate according to this embodiment includes a chip placement step S1, a damaged layer formation step S2, a sealing step S3, and a grinding step S4.

In the chip placement step S1, as shown in FIG. 3(a), chips 60 are placed on the surface 11a of the substrate 11. Examples of chips 60 include device chips on which ICs (integrated circuits) and optical elements are formed. There is no limit to the number of chips 60 to be placed or the arrangement method, and the chips 60 are placed according to the design of the resin-sealed substrate to be manufactured. In this embodiment, the rectangular parallelepiped chips 60, which have four sides in addition to a front surface (top surface) and a back surface (bottom surface), are placed at approximately equal intervals.

Methods for placing the chip 60 on the substrate 11 include, for example, die bonding and wire bonding. In die bonding, the back surface of the chip 60 and the surface 11a of the substrate 11 are fixed using a conductive adhesive. In wire bonding, the electrodes of the chip 60 and the electrodes of the substrate 11 are joined via metal by thermocompression or the like. The chip 60 may also have a silicon through electrode or the like formed thereon to achieve bonding.

In the damage layer formation step S2, as shown in FIG. 3(b), a damage layer 62 is formed on the surface of the chip 60. FIG. 4 is an enlarged cross-sectional view of the substrate 11, chip 60, and damage layer 62 shown in FIG. 3(b). The damage layer 62 is provided to promote the dressing effect of the grinding wheel 42 in the grinding step S4 described later, and has an uneven structure exposed on its upper surface, which becomes the grinding surface (the surface that contacts the grinding wheel 42), as shown in FIG. 4. This uneven structure makes the grinding wheel 42 more susceptible to wear, promoting dressing. The surface roughness Ra of the damage layer 62, which is an indicator of the uneven structure, is preferably Ra>0.1 μm.

The method of forming the damage layer 62 is not particularly limited, but an example is a method of irradiating the upper part of the chip 60 with a laser beam. When forming the damage layer by irradiating a laser beam, the wavelength of the laser beam is selected to be, for example, a wavelength that is absorbed by the chip 60. However, a wavelength that is transmitted through the chip 60 may also be selected as the wavelength of the laser beam. In this case, the laser beam is focused on the upper part of the chip 60, thereby modifying the upper part of the chip 60 and forming an uneven structure.

When a laser beam having a wavelength absorbed by the chip 60 is irradiated onto the surface of the chip 60 to form the damage layer 62, for example, the output of the laser beam is set to 0.2 W, the frequency of the laser beam oscillation is set to 200 kHz, and the speed (feed rate) of relative movement between the laser beam and the chip 60 in a direction parallel to the surface of the chip 60 is set to 500 mm/s.

In addition, a method of grinding the upper part of the chip 60 may be adopted as a method of forming the damage layer 62. When forming the damage layer 62 by grinding, for example, a grinding wheel including a grinding stone having a grain size of #320 is used, and the rotation speed of the spindle that rotates the grinding wheel is set to 3200 rpm, the rotation speed of the chuck table that holds the chip 60 is set to 300 rpm, and the speed (feed rate) of the relative movement between the grinding wheel and the chuck table in a direction perpendicular to the surface of the chip 60 is set to 2 μm/s. The grain size of the grinding stone is a standard specified in JIS (Japanese Industrial Standards) R6001.

As shown in FIG. 3, in this embodiment, the damage layer 62 is formed on the chip 60 after the chip 60 is placed on the substrate 11. However, the damage layer 62 may be formed on the chip 60 before the chip 60 is placed on the substrate 11. In this case, the chip 60 with the damage layer 62 formed is placed on the substrate 11. In other words, either the chip placement step S1 or the damage layer formation step S2 may be performed first.

Next, the sealing step S3 is performed. In the sealing step S3, as shown in FIG. 3(c), at least a portion of the surface 11a of the substrate 11 and the side and surface (top surface) of the chip 60 are covered with resin 64, so that the chip 60 and the resin 64 are integrated and fixed to the surface 11a side of the substrate 11. In other words, the chip 60 is sealed by the resin 64.

Resin (sealing resin) 64 is provided to protect chip 60 from moisture in the air and light. There are no particular limitations on the material of resin 64, but for example, thermosetting epoxy resin, urethane resin, silicone resin, etc. can be used as resin 64.

One method for forming the resin 64 is, for example, to place a mold (metal mold) so as to cover the chip 60 to be sealed, fill this mold with the resin that is the raw material for the resin 64, soften and melt it, and then harden the resin. However, the method for forming the resin 64 is not limited to this.

Next, grinding step S4 is performed. In grinding step S4, as shown in FIG. 3(d), the portion of the resin 64 above the chip 60 is ground and removed to expose the surface (top surface) of the chip 60 from the resin 64. This completes the resin-encapsulated substrate 66.

When exposing the top surface of the chip 60, the grinding device 2 grinds away the resin 64 and also grinds away the damaged layer 62 formed on the top of the chip 60.

The action and effect of the above-mentioned damage layer 62 will be explained with reference to the drawings. FIG. 5 is a cross-sectional view showing the state in which the resin 64 of the resin-sealed substrate 66 shown in FIG. 3(d) is being ground away. FIG. 6 is an enlarged view of a portion (encircled portion) of FIG. 5.

As shown in Figures 5 and 6, when exposing the tip 60, the portion of the resin 64 above the tip 60 is first ground and removed by the grinding wheel 42. Next, the grinding wheel 42 grinds the damaged layer 62, but because the damaged layer 62 has an uneven structure, the grinding wheel 42 is dressed by the uneven structure of the damaged layer 62.

In this way, the grinding wheel 42 is dressed by the damaged layer 62 when the upper part of the tip 60 is exposed from the resin 64, so the increase in the grinding load caused by the change in the grinding material is suppressed. Therefore, the increase in the current value of the current flowing through the motor for rotating the spindle 32 is suppressed.

A second embodiment of the present invention will now be described. FIG. 7 is a cross-sectional view of a resin-sealed substrate 66 according to the second embodiment. FIG. 8 is a cross-sectional view that shows a schematic diagram of the state in which the resin 64 of the resin-sealed substrate 66 shown in FIG. 7 is being ground.

As shown in FIG. 7, the resin-sealed substrate 66 according to the second embodiment has a plurality of chips 60 of different thicknesses arranged on the surface 11a of the substrate 11. Typically, each of the plurality of chips 60 is configured to have a different thickness. Note that in FIG. 7, the chips 60 are arranged so that the thickness increases from left to right, but the arrangement method of the chips 60 is not limited to this.

By arranging multiple chips 60 of different thicknesses on the substrate 11, as shown in FIG. 8, the timing at which the thicker chips 60 and the thinner chips 60 are exposed and ground is shifted. In other words, dressing of the grinding wheel 42 (wear and tear of the grinding wheel 42) is promoted at multiple different times, so that the condition of the grinding wheel 42 is maintained in good condition for a long time compared to the configuration of embodiment 1, and an increase in the grinding load is better suppressed.

In addition, the structures, methods, etc. according to the above-described embodiments may be modified as appropriate without departing from the scope of the present invention.

2: Grinding device 4: Base 4a: Opening 6: X-axis movement mechanism 8: Table cover 10: Dust-proof/water-proof cover 12: Chuck table 12a: Upper surface 14: Support structure 16: Z-axis movement mechanism 18: Guide rail 20: Movement plate 22: Screw shaft 24: Motor 26: Support 28: Grinding unit 30: Spindle housing 32: Spindle 34: Mount 36: Bolt 38: Grinding wheel 40: Wheel base 42: Grinding stone 44: Thickness measuring device 46: First height gauge 48: Second height gauge 50: Controller (control unit)
52: Processing device 54: Storage device 56: Input device 60: Chip 62: Damaged layer 64: Resin 66: Resin-sealed substrate 11: Substrate 11a: Front surface 11b: Back surface

Claims (4)

A method for manufacturing a resin-encapsulated substrate including a substrate, a chip provided on an upper surface of the substrate, and a resin covering the chip, comprising the steps of:
a chip placement step of placing the chip on an upper surface of the substrate;
a damage layer forming step of forming a damage layer on an upper surface of the chip before or after the chip arrangement step;
a sealing step of coating at least a portion of the upper surface of the substrate and the side and upper surface of the chip with the resin to integrate the chip and the resin and fix them to the upper surface of the substrate, thereby sealing the chip;
a grinding step of removing a portion of the resin above the chip with a grinding wheel to expose an upper surface of the chip from the resin and form the resin-encapsulated substrate;
In the grinding step, the damaged layer is ground together with the resin. The method for manufacturing a resin-encapsulated substrate according to claim 1, wherein in the chip placement step, multiple chips having different thicknesses are placed on the upper surface of the substrate. The method for manufacturing a resin-encapsulated substrate according to claim 1 or 2, wherein in the damage layer forming step, the damage layer is formed on the upper surface of the chip by irradiating the upper surface of the chip with a laser beam having a wavelength that can be absorbed by the chip. The method for manufacturing a resin-encapsulated substrate according to claim 1 or 2, wherein in the damage layer forming step, the damage layer is formed on the upper surface of the chip by grinding the upper surface of the chip with the grinding wheel.

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