JP2002270627A - Semiconductor device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the planarity of a seal resin surface formed by a potting mold for increasing the number of semiconductor devices which can be obtained from an aggregate substrate. SOLUTION: The method comprises double application of a dam material by a dispenser to form a dam 11 surrounding semiconductor elements 5 mounted on an aggregate substrate 30, dropping liquid resin on regions sectioned by the dam 11 so as to cover the semiconductor element 5 with a dropping quantity which is adjusted so that the height of the liquid resin surface over the central portion of the region, after completing the dropping, is aligned with the arcuate center of an approximately arcuate inner side of the dam 11 top, thereby expanding the area of a flat surface of the liquid resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device formed by a resin encapsulation method using a liquid resin, and more particularly to a method capable of obtaining a flat surface of an encapsulation resin.

[0002]

2. Description of the Related Art In order to protect a semiconductor element mounted on a lead frame or a wiring board from corrosion or the like, resin sealing by transfer molding or potting molding has been conventionally performed. The former forms a large amount of packages at a time in a mold, and is suitable for resin sealing of a semiconductor element mounted on a lead frame. On the other hand, the latter potting mold is a method of forming a package by dropping a liquid resin on a semiconductor element and curing it, and is not suitable for mass production.However, as in the transfer mold described above, excessive heat history and injection pressure Is not given, there is no risk of a change in the characteristics of the element. In addition, as portable devices and the like require a so-called chip size package (CSP), the miniaturization of the package is in the direction of progress in the future. However, when such a small package is formed by transfer molding, a considerable injection pressure is required because a resin flow path such as a gate is narrowed with miniaturization of a cavity. As a result, resin is not filled, voids are mixed,
Further, various problems such as breakage of the wire may be caused. In that respect, the potting mold allows the resin to be applied reliably, and furthermore, it is not necessary to apply extra stress to the element and the wiring, so that there is almost no physical problem, and in that sense, an extremely small package is formed. It can be said that it is suitable for.

A conventional method for manufacturing a semiconductor device using a potting mold will be described below with reference to FIG. (A) is a cross-sectional view showing a state after the completion of the potting mold in the manufacturing process of the semiconductor device.
(B) is a top view of (a), and (c) is a perspective view of the finally obtained semiconductor device. In this figure, 1 is a substrate, 2a is a metal wiring, 2b is a die pad,
2c is an electrode, 3 is a through hole, 4 is a bonding wire, 5 is a semiconductor element, 6 is a sealing resin, 7 is a resist film,
Reference numeral 11 denotes a dam, 30 denotes an aggregate substrate, and 31 denotes a semiconductor device.

[0004] This type of manufacturing method is based on firstly the collective substrate 30
, Secondly, the step of covering the opening of the through hole 3, thirdly, the step of mounting the semiconductor element 5, fourthly, the step of forming the dam 11, and fifthly, the sealing resin 6 is formed. There is a step, and finally, a step of individualizing the semiconductor element 31 into a single unit.

[0005] The process of forming the first collective substrate substrate 30 includes the steps of forming metal wiring 2a and die pad 2b on the front and back of the substrate 1 made of an insulator such as glass epoxy by etching a copper foil or the like.
And an electrode 2c, and a through hole 3 for electrically connecting them is mainly formed by plating or the like.

In the step of covering the opening of the second through hole 3, a dry film solder resist is laminated on the entire surface of the collective substrate 1, and is exposed and developed to cover the opening of the through hole 3. A resist film 7 is selectively formed.

The steps of mounting the third semiconductor element 5 include applying a silver paste on the die pad 2b, die bonding of the semiconductor element 5 by a chip mounter, and bonding wires 4 between the semiconductor element 5 and the metal wiring 2a by a wire bonder. Electrical connection is mainly performed via the. However,
The semiconductor element 5 may be a flip chip, and a method by flip chip bonding may be adopted.

In the step of forming the fourth dam 11, application and hardening of the dam material using a dispenser is mainly performed. That is, a resin such as silicon is filled into a syringe with a dam material, which is a main material, and the dam material is extruded at a predetermined discharge pressure while moving along the outer periphery of the surface of the collective substrate 30, and is cured at a predetermined temperature. The dam 11 is formed.

In the step of forming the fifth sealing resin 6, a so-called potting mold, in which a liquid resin is applied to a region surrounded by the dam 11 and cured, is performed.

In the last individualization step, as shown in FIG. 4B, dicing lines are determined in a matrix so as to be divided into unit semiconductor device forming regions 8 (one semiconductor device which has not been divided yet). The semiconductor device 31 is cut along the dicing line with a blade or the like to obtain individual semiconductor devices 31 as shown in FIG. The semiconductor device 31 thus obtained has an LCC (Lead-less Chip Carrier) structure in which the side through 10 is exposed on the side surface.

[0011]

However, when potting molding is performed in the fifth step in a region surrounded by the dam 11 formed in the fourth step, the formed sealing resin 6 is moved from the center of the dam 11. The length Ls is required until the sealing resin 6 becomes flat. Although the length Ls depends on the properties of the resin, it is generally about 7 to 1 in an epoxy type generally used.
It is about 0 mm. That is, since the surface of the sealing resin 6 is inclined near the dam, the semiconductor device 31 obtained by separating from the unit semiconductor device formation region 8 located near the dam is shown in FIG.
As shown in (c), the thickness of the package is not uniform. If the semiconductor device 31 is formed using only the region where the surface of the sealing resin 6 is flat, the number of components to be formed is reduced, the cost is increased, and more members are discarded. In addition, since the resin 6 has the lowest part in contact with the dam 11, voids contained in the resin
There is also a problem that the semiconductor device easily aggregates at the center of the zero and the semiconductor device at that portion becomes defective.

Furthermore, since the difference in thermal expansion between the dam member and the substrate is large, there is a problem that the aggregate substrate 30 is warped when the dam 11 is cured. Although there is a countermeasure such as forming the dam 11 with a low elastic resin, there is a problem that the resin hardening time takes 5 hours or more. Further, there is a method of narrowing the dam region, but this leads to a problem that the number of semiconductor devices 31 to be manufactured is reduced.

[0013]

Means for Solving the Problems To solve the above problems, a first invention is to form a dam by applying a dam material with a dispenser so as to surround a semiconductor element mounted on a collective substrate, In a method of manufacturing a semiconductor device in which a liquid resin is dropped into a region defined by the dam so as to cover a semiconductor element, the dam material is double-coated to form a dam having an inner surface with a substantially circular arc cross section. When the liquid resin is dropped, the height of the liquid resin surface at the center of the area after the completion of the drop is made to coincide with the substantially center of the substantially circular arc, and the drop amount is increased so as to increase the area of the flat surface of the liquid resin surface. Is adjusted. With this configuration, the inner surface of the upper layer of the dam where the liquid resin is doubled (the portion formed by application later) contacts the inner surface at a height near the center of the arc, and at the contact position, the influence of wettability is small. Therefore, the amount of deformation of the liquid resin surface is reduced.

According to a second aspect of the present invention, in the first aspect, when the dam material is applied twice, the amount of the dam material to be applied later is larger than that of the dam material to be applied first, and the dam material is applied first. It is characterized in that the dam material forms a core dam. With such a configuration, the dam material applied later has good wettability with the dam material applied earlier than the collective substrate, does not spread much on the collective substrate, and has a cross section due to the surface tension of the dam material applied later. The shape becomes closer to a circle.

According to a third aspect, in the first or second aspect, when the liquid resin is dropped, the height of the surface of the dropped liquid resin is highest at a portion in contact with the dam. It is characterized in that voids do not collect at the center of the liquid resin (the center of the semiconductor formation region) after the application is completed, but are instead collected to the outermost side.

In a fourth aspect based on the first to third aspects, the dam is formed for each unit semiconductor device formation region, and the dam is formed along the gap between the adjacent unit semiconductor device formation regions. The substrate is cut into individual semiconductor devices, and the stress applied to the collective substrate by the dam is distributed to each unit semiconductor device formation region.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same reference numerals as those in FIG. 4 described above indicate the same or corresponding components.

FIG. 1 shows an embodiment of the present invention, in which (a)
FIG. 7 is a cross-sectional view showing a state after completion of a resin sealing step, (b) is a plan view showing a state of dicing line selection in a dicing step, and (c) is a perspective view of a semiconductor device obtained after completion of a cutting step.

Next, the manufacturing method will be described. Since the steps up to the step of mounting the semiconductor element 5 on the collective substrate 30 are the same as those in the related art, the description will be omitted, and the description will be started from the step of forming the dam. First, an operation sequence and a discharge pressure of a dispenser (not shown) are set in advance. At this time, the syringe of the dispenser is set so as to move along the outer peripheral edge of the collective substrate 30, and it is programmed to repeat this twice. In addition, the operating speed and the discharge pressure of the syringe are set so as to provide a dam having a height higher than these so that the semiconductor element 5 and the wire 4 can be sufficiently covered in consideration of the amount of the liquid resin to be described later. Next, the syringe is filled with dam material, and the dam material employed at this time is preferably a quick-drying material that leaves a curved surface without damaging the dam surface, has good wettability with the liquid resin, and after curing. It is desirable that the residual stress is extremely low. For example, in the case of an epoxy-based resin generally used as a liquid resin, a quick-drying dam material mainly composed of a silicon resin is used. In this example, the viscosity 7
0 Pa · s Dow Corning Silicone (trade name,
(Manufactured by Toray Industries, Inc.). This can be used only by natural curing for about 10 minutes, and the productivity is good.

After the preparation described above, the dispenser is moved in accordance with the previously set sequence, and at the same time, the dam material is discharged onto the collective substrate 30 to form the double dam 11. This dam 11 is a two-layer dam-shaped dam as shown in FIG. 1 (a), and the cross section of the upper layer surface draws an arc. However, the surface required in the present invention is only the inner surface in contact with the liquid resin, and it is sufficient that even this portion has a circular cross section. It is sufficient that an arc close to a perfect circle can be obtained stably, but due to fluctuations in the discharge pressure of the dispenser, fluctuations in the viscosity of the dam material, and the like,
The shape may be slightly similar to an elliptical arc.

Next, the liquid resin is dropped into a region surrounded by the dam 11 by a dispenser. At this time, the dripping amount is adjusted to an amount such that the liquid resin after the dripping is in contact with the upper layer of the dam 11 and sufficiently covers the semiconductor element 5 and the wire 4. The amount of dripping is based on the fact that the height of the liquid resin surface at the center of the area defined by the dam 11 after the completion of dripping substantially coincides with the center of the arc described above. Since the deformation occurs near 11, the height does not always match between the vicinity of the dam 11 and the center. In extreme cases, FIG. 1 (a)
In some cases, the liquid resin contacts only the lower layer of the dam, as shown by the dotted line, so that the deformation of the liquid resin near the dam should be minimized, that is, experiments should be performed in advance to maximize the flat surface of the liquid resin surface. It is important to know the amount of dripping by using this method. In addition, since the thing shown in FIG. 1A has the intention described later, the liquid resin is intentionally applied to the dam 11.
Deformation is performed in such a way as to crawl up, but depending on the adjustment method, this deformation can be almost eliminated, and Ls
Is, for example, 0 to 3 mm compared to the conventional 7 to 10 mm.
It can be.

Next, the dropped liquid resin is cured at a predetermined temperature and time. At this time, the void moves to the highest point on the liquid resin surface. Here, the voids are bubbles generated by air or the like that is entrained when the liquid resin is dropped or gas originally dissolved in the liquid resin. As described above, the place where the surface of the liquid resin is highest is the dam 1
Since the deformed portion is in contact with 1, voids having increased buoyancy due to thermal expansion gather there.

Next, as shown in the plan view of FIG.
A dicing line is determined in a matrix so as to be divided into the unit semiconductor element regions 8, and a blade is run along the dicing line to cut the dicing lines, thereby forming individual semiconductor devices 31 as shown in FIG. At this time, dicing is performed so that the portion of the sealing resin 6 having the largest thickness, that is, the portion including the void near the dam 11 is not incorporated into the semiconductor device 31.

Since the present embodiment is configured as described above, all the semiconductor devices 3 taken from the same collective substrate 30
1 can make the thickness of the sealing resin uniform. Alternatively, since the portion of the resin surface near the dam 11 where the resin surface is deformed is reduced, the number of semiconductor devices 31 having a uniform thickness can be increased. Moreover, since the voids are diced and removed together with unnecessary portions of the collective substrate 30, the yield can be improved.

FIG. 2 is a cross-sectional view showing another embodiment using a semiconductor device having a BGA structure as an example. The manufacturing method in this case is such that a double-formed dam 11 is formed for each unit semiconductor formation region so as to surround the outer peripheral edge thereof, and that a solder ball 21 is mounted on the electrode 2c by a ball mounter before dicing. The other points are the same as those of the above-described embodiment. The through hole 3 is filled with a filling resin 22.

By forming the dam 11 in each unit semiconductor formation region, the problem of warpage of the collective substrate 30 due to a difference in thermal expansion between the collective substrate 30 and the dam 11 is suppressed. That is, conventionally, since the dam was formed in a continuous frame shape, the aggregate substrate was subjected to a large bending stress in the length direction, particularly in the long direction, but in this example, the dam only applies stress to a small area. Therefore, a bending stress that warps the entire collective substrate does not work. Note that dicing is performed between the dams formed in adjacent unit semiconductor formation regions, and the dams 11 remain in the semiconductor device 31 as shown in FIG. However, the surface flatness of the sealing resin 6 can be improved as described above,
In addition, since the sealing resin 6 is divided into small areas, the absolute amount of voids is small and there is no problem. Therefore, it does not cause appearance defects or the like, and can be put on the market with the dam 11 remaining as it is.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the spirit of the claims. For example, in the first embodiment,
By applying a larger amount of dam material to be applied later than the dam material to be applied first, as shown in FIG.
3 is a core, and a dam is formed such that the dam is covered by an upper dam material 24. At this time, the dam material in the upper layer is less likely to wet and spread on the collective substrate, and the inner layer cross section of the upper layer of the dam becomes a circular arc closer to a perfect circle due to the surface tension of the dam material.
The dam is desirably formed after wire bonding so that the dam does not fall off due to an external force during the transportation process. However, the dam may be formed during substrate manufacturing before die bonding.

[0028]

As described above, since the present invention utilizes a potting mold, a dam can be easily formed at low cost without using an expensive mold or the like. Further, it has the following effects.

Since the flat portion of the resin can be expanded, the thickness variation of the semiconductor device can be suppressed, and the number of members to be discarded can be reduced. This also leads to an increase in the number of semiconductor devices to be obtained, so that costs can be reduced.

When a dam is formed in a double form, as shown in FIG. 3, the amount of dam material to be applied later is made larger than that of dam material to be applied first, and the dam material applied first becomes a core. By forming the dam, a good surface for bringing the liquid resin into contact with the inner surface of the dam can be stably formed.

If the thickness of the sealing resin is set to be the largest at the portion in contact with the dam, the location where the voids are generated may be affected by the entry of moisture into the portion that does not become a product or the semiconductor element or the bonding wire. Since there is no corner, the yield can be improved.

Further, a dam is formed for each unit semiconductor device forming region, and the collective substrate is cut along the dam between the adjacent unit semiconductor device forming regions to form individual semiconductor devices. Even when a large-area collective substrate with a large number of pieces to be removed is used, handling troubles and the like do not occur, and productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a semiconductor device substrate and a semiconductor device according to the present invention.

FIG. 2 is a view showing another example of a semiconductor device substrate and a semiconductor device according to the present invention.

FIG. 3 is a diagram showing an embodiment of a dam shape on a semiconductor device substrate according to the present invention.

FIG. 4 is a view showing a conventional semiconductor device substrate having an LCC structure and a semiconductor device.

[Explanation of symbols]

1: substrate, 2a: metal wiring, 2b: die pad, 2
c: electrode, 3: through hole, 4: bonding wire, 5: semiconductor element, 6: sealing resin, 7: dry film solder resist, 8: unit semiconductor device formation region, 10: side through, 11: dam , 21: solder ball, 22: filling resin, 23: dam applied first time,
24: Dam applied second time, 30: Collective substrate, 31:
Semiconductor device

Claims (4)

[Claims] 1. A dam material is applied by a dispenser so as to surround a semiconductor element mounted on an aggregate substrate to form a dam, and a liquid resin is applied to a region defined by the dam so as to cover the semiconductor element. In the method for manufacturing a semiconductor device to be dropped, the dam material is double-coated, a dam having an upper inner side surface having a substantially circular cross section is formed, and when dropping the liquid resin, the center of the region after the dropping is completed. A height of the liquid resin surface of the portion is made substantially coincident with a substantially center of the substantially circular arc, and a dripping amount is adjusted so as to increase an area of the flat surface of the liquid resin surface. 2. When the dam material is applied twice, the amount of the dam material to be applied later is made larger than that of the dam material to be applied first, so that the dam material applied first forms a core. 2. The method for manufacturing a semiconductor device according to claim 1, wherein: 3. The method according to claim 1, wherein, when the liquid resin is dropped, the height of the surface of the liquid resin dropped is highest at a portion in contact with the dam.
13. The method for manufacturing a semiconductor device according to item 5. 4. The method according to claim 1, wherein the dam is formed for each unit semiconductor device formation region, and the aggregate substrate is cut along the gap between the adjacent unit semiconductor device formation regions to form individual semiconductor devices. The method for manufacturing a semiconductor device according to claim 1, wherein: