JP4376247B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a resin sealing device and a method for manufacturing a semiconductor device, and more particularly to a technique for resin sealing a semiconductor chip.

  As one method of encapsulating a semiconductor chip, a method of sealing a semiconductor chip with a resin (for example, epoxy resin) using a mold is known. In this method, a lead frame on which a semiconductor chip is mounted is set in a mold, a resin tablet placed in a pot is pushed out by a plunger, and the fluidized resin is guided to a cavity space of the mold. The mold shown below is an example, and there are various other types.

  A conventional resin sealing device 100 for resin-sealing a semiconductor chip will be described with reference to the drawings. FIG. 4 is a cross-sectional view showing an outline of the configuration of the sealing device 100 when the sealing process is performed, and FIG. 5 shows that the upper die 101 of the resin sealing device 100 is brought into contact with the lower die 102. It is the top view seen from the surface side. 4 is a cross-sectional view taken along line XX in a state in which the upper mold 101 in FIG. 5 is in contact with the lower mold 102.

  As shown in FIG. 4, the resin sealing device 100 includes an upper mold 101 and a lower mold 102. A plurality of spaces (cavities 103) in which semiconductor chips as sealed bodies are arranged are provided on the contact surface between the upper mold 101 and the lower mold 102. The lower mold 101 is provided with a pot 106 for accommodating a resin tablet 105 pressed by a plunger 104 having a vertical mechanism. The upper mold 101 has a cull 107 at a position corresponding to the pot 106, a gate 108 at a position corresponding to between the pot 106 and the cavity 103, and a runner 109 at a position corresponding to between each cavity 103. Each is formed.

  Further, when the resin is guided from the pot 106 to the cavity 103, the air vent 110 for exhausting the air of the gate 108, the cavity 103, and the runner 109 to the outside is the upper mold 101, and communicates with the cavity 103. Is provided.

  Further, a packing 111 made of, for example, rubber is formed in an annular shape on the outer periphery of the contact surface between the upper mold 101 and the lower mold 102 as a seal member for sealing the space of the contact surface. Each pot 106 is connected by a pot connection path 112.

The above-described resin sealing device and a method for manufacturing a semiconductor device using the same are described in, for example, the following patent documents.
JP 2000-31180 A Japanese Patent Laid-Open No. 10-144713

  However, when the sealing process is performed using the conventional resin sealing device 100 described above, a resin burr may be generated in the air vent 110. The resin burr is surplus resin that has passed through the cavity 103 and is pushed out to the air vent 110 side.

  As a result, the air vent is clogged, degassing in the cavity is reduced and problems such as unfilled defects occur, a resin burr removal process is required, the burden of visual inspection increases, and resin burrs are scattered. As a result, a device having desired operation characteristics cannot be obtained because it is mixed in the next sealing step, and the yield is reduced.

  In addition, the transparent resin used for sealing the light receiving element or the like has a problem of resin burrs as compared with a general black resin, and a resin sealing device that solves this problem and a semiconductor device using the resin sealing device. The production method has not been sufficiently studied.

  One of the reasons why the transparent resin has a problem of resin burrs as compared with the black resin is considered to be because the transparent resin does not contain a filler like the black resin and has high fluidity. Specifically, for example, a general black resin flows and hardens by about 98 cm at 180 ° C., whereas a transparent resin flows and hardens by 150 cm at 150 ° C. Accordingly, there has been a demand for a resin sealing apparatus that can satisfactorily perform resin sealing with high fluidity such as a transparent resin, and a manufacturing method using the apparatus. In addition, the filler here is a resin that makes the thermal expansion coefficients of the Si chip and the resin coincide with each other as much as possible, and relaxes the stress applied to the chip. Naturally, since the powder of Si is mixed, the viscosity becomes high. On the other hand, a resin used for an optical IC or the like needs to be transparent to light, and if the light is irregularly reflected by a filler, desired operation characteristics cannot be obtained. For this reason, no filler is mixed into the transparent resin.

  Therefore, the main object of the present invention is to suppress the generation of resin burrs and improve the reliability and yield of the device after sealing. It is another object of the present invention to provide a resin sealing device suitable for sealing using a highly fluid resin such as a transparent resin and a method for manufacturing a semiconductor device using the device.

  The present invention has been made in view of the above problems, and the main features are as follows. That is, the resin sealing device of the present invention includes an upper mold, a lower mold, and a pot for charging resin, communicated with the pot, and formed in a contact surface between the upper mold and the lower mold A resin sealing device for resin-sealing a semiconductor chip disposed in the cavity by filling the resin therein, wherein a resin flow including the cavity in at least one of the upper mold and the lower mold A through-hole that exposes the contact surface to the outside without directly communicating with the road is provided.

  Further, in the semiconductor device of the present invention, a concave step portion is provided in a region where the resin flow path is not formed in the contact surface of the mold on the side where the through hole is provided, and the step portion and the step The through-hole is connected.

  The main features of the semiconductor device manufacturing method of the present invention are as follows. That is, the method for manufacturing a semiconductor device of the present invention is a method for manufacturing a semiconductor device including a step of sealing a semiconductor chip using the resin sealing device, wherein the semiconductor chip is divided into the upper mold and the lower mold. Placing the semiconductor chip in the cavity by sandwiching, sealing the semiconductor chip by charging resin from the pot, filling and curing the resin in a resin flow path including the cavity, and And the gas in the resin flow path is exhausted to the outside through the through hole.

  In addition, the semiconductor device manufacturing method of the present invention includes a step of depressurizing the space of the resin flow path by operating a vacuum pump. Further, after the step of depressurizing the space of the resin path, there is a step of releasing the operation of the vacuum pump and then maintaining the state until the resin is cured. Furthermore, the resin is a transparent resin.

  In the resin sealing device of the present invention, a deaeration through-hole is formed in a region including a cavity and excluding a path through which resin flows (hereinafter referred to as a resin flow path). That is, the through hole is not in direct communication with the resin flow path. Therefore, generation | occurrence | production of the resin burr | flash can be suppressed. In addition, since the resin flow path can be deaerated through the through hole, it is possible to prevent the occurrence of void defects and unfilled defects.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an outline of the configuration of the resin sealing device 1 when the sealing step is performed. FIG. 2 is a plan view of the upper mold 2 of the resin sealing device 1 as viewed from the contact surface side with the lower mold 3. 1 is a cross-sectional view taken along line YY in a state where the upper mold 2 in FIG. 2 is in contact with the lower mold 3.

  As shown in FIG. 1, the resin sealing device 1 of the present embodiment includes an upper mold 2 and a lower mold 3. And the predetermined position of the contact surface of the upper metal mold | die 2 and the lower metal mold | die 3 is processed into the concave shape, and the cavity 4 is provided because each recessed part faces. An object to be sealed is disposed in the cavity 4. There are various types of objects to be sealed.

  For example, a known structure such as a lead frame, a flexible sheet, a ceramic substrate, a metal substrate, a printed board, or an electrode called ISB sealed without a frame.

  The lead frame has an island in which at least one chip is provided in the center, an inner lead having one end adjacent to the periphery of the island, and the other end integrated with the inner lead and extends outside the sealing body. There is an outer lead, and in order to support these, the connecting body is integrally arranged between the inner lead and the outer lead, outside the outer lead, and the island is supported integrally with the connecting body, and the whole is It is supported in one piece. A chip is mounted on the island, and the chip and the inner lead are electrically connected. The lead frame provided with the chip is placed in the cavity.

  Then, what uses a flexible sheet, a ceramic substrate, a metal substrate, or a printed circuit board (a single layer or a multilayer) as a support substrate is demonstrated. There is also an island where chips are placed, and leads are provided around the island. Unlike the lead frame, since there is a support substrate, the lead and the island do not require a connecting body or a suspension lead. In many cases, an external electrode is provided on the back surface of the substrate. However, in the case of a metal substrate, it is difficult to provide an electrode on the back surface, and thus a lead fixing pad may be provided around the substrate. The types using these support substrates are those in which one chip is mounted, those in which a plurality of chips are mounted three-dimensionally in the vertical direction or in a plane type in the horizontal direction, and further, passive elements and semiconductor chips are mounted. , There is something that is configured as a system-in-package. In some cases, one layer of electrodes is provided on the support substrate, and in other cases, the support substrate is removed and only the electrodes are held in the resin.

  In ISB, the Cu foil plate is half-etched, islands and lead electrodes are arranged in a projecting shape, and a chip is electrically connected thereon. This type also has one chip mounted, a plurality of chips mounted three-dimensionally in the vertical direction or a plane type in the horizontal direction, and a passive element and a semiconductor chip are mounted on the system in package. There is something that consists of Then, after the sealing described below, the back surface of the Cu foil plate is removed to separate islands and leads.

  Furthermore, although it is the shape of the cavity 4 of the upper metal mold | die 2 and the lower metal mold | die 3, either one may be flat.

  The lower mold 3 is provided with a pot 7 for accommodating a resin tablet 6 pressed by a plunger 5 having a vertical mechanism. Depending on the design, the upper mold 2 may be provided with a pot 7.

  The upper die 2 has a cull 8 at a position corresponding to the pot 7, a gate 9 and a runner at a position corresponding to between the pot 7 and the cavity 4, and a runner at a position corresponding to between the cavities 4. 10 are each formed in a concave shape. Thus, the cavity 4, the pot 7, the gate 9, and the runner 10 communicate with each other as a resin flow path.

  Further, the upper mold 2 is formed with a through hole 11 that penetrates the upper mold 2 and exposes the contact surface with the lower mold 3. As shown in FIG. 2, the through hole 11 communicates with the outside of the upper mold 2 without directly communicating with the resin flow path including the cavity 4, the cull 8, the gate 9, and the runner 10. The diameter of the opening of the through hole 11 is about 4 mm, for example. However, as will be described later, it is considered that the through-hole 11 indirectly communicates with the resin flow path through a very small gap on the contact surface. The extremely small gap referred to here is a slight gap generated on the contact surface other than the resin flow path even if the upper mold 2 and the lower mold 3 are apparently completely clamped. The thickness is such that the resin cannot flow but the gas can move. Logically, if the abutment surfaces of the upper and lower molds are flat, there will be no gap between them, and fluid materials will never enter, but in reality the resin will not flow but the gas will move It is considered that there is a gap as much as possible.

  In addition, from the viewpoint of improving the deaeration characteristics by the through holes 11, it is preferable to arrange a plurality of through holes 11 in the vicinity of the resin flow path. Similarly, from the viewpoint of improving the deaeration characteristics, as shown in FIG. 2, a concave dent (step 20) is provided on the contact surface side of the upper mold 2 in the vicinity of the resin flow path. You may connect the bottom part of this and the through-hole 11. FIG. The depth of the stepped portion 20 is about 2 cm, for example.

  Here, referring to FIG. 2, the upper through hole 11 is disposed between the cull 8 and the two gates 9. The through-holes 11 provided in a line on the left and right are provided around the cavities 4 arranged in a matrix, that is, four sides here, but on the two opposite sides. Further, it is provided between two cals 8. In some cases, as shown in FIG. 2a, the cavity rows 4, 4, 4,... And the cavity rows 4, 4, 4,. When the space between the cavity rows 4, 4, 4... And the cavity rows 4, 4, 4... Is short (for example, about 2 mm) In this case, since support pillars, index mark pins, and the like are arranged, it is difficult to arrange the through hole 11 at the site, but it is better to provide it near the resin flow path including the cavity 4. So it is better to place it if possible.

  Further, the stepped portion 20 is a gas intrusion region, and it is considered that the gas from the cavity is more easily taken in if there is a slight groove. Therefore, in FIG. 2, the stepped portion 20 is disposed around the cull 8 and the pot connecting path 16, but the stepped portion 20 may be disposed at the end of the mold and the through hole 11 may be formed there. One through hole 11 may be provided for one stepped portion 20, or a plurality of through holes 11 may be provided for one stepped portion 20.

  Further, a packing 12 made of, for example, rubber is provided in an annular shape as a seal member on the outer periphery of the contact surface between the upper mold 2 and the lower mold 3. Further, a vacuum pump 13 communicating with the resin flow path is connected via a predetermined valve 14 and an exhaust pipe 15. Each pot 7 is connected by a pot connection path 16. In FIG. 2, the vacuum pump 13, the valve 14, and the exhaust pipe 15 are provided on the lower mold 3 side. Furthermore, as shown in FIG. 3, a mold base 21 covering the entire mold including the upper mold 2 and the lower mold 3 is arranged, and an exhaust pipe 22 and a vacuum pump 23 are arranged on the mold base 21. You can also.

  In FIG. 2, the pot connection path 16 is arranged in order to make the pressure of the cavity of the entire mold uniform. However, the connection path 16 may be omitted depending on the design.

  Cavity 4 ... There is a groove shaped like a letter T at the end of the row, but this is a dummy cavity, and the resin is pushed into this cavity, so it is unfilled poorly Is suppressed.

  The object of the present invention is achieved by the following idea. That is, a resin that is transparent to light, which is not mixed with a filler, has a low viscosity.

  Conventionally, resin burrs have occurred in the air vent due to the low viscosity. The air vent was removed to remove the resin burr. If there is no escape route for gas in the space from the cal to the dummy cavity, an exhaust pipe was placed as forced exhaust.

  Originally, the gas is eliminated by this forced exhaust, so when the resin is filled in the cavity 4, the void should disappear. However, since the resin is heated at a high temperature, outgas is generated from the resin itself, which remains as a cause of the void. This is because extra gas is generated because the filler is not mixed with the resin.

  In the present invention, this gas may be released somewhere. However, since the packing 12 is provided around the outside of the mold contact area, there is no escape path, and therefore, a through hole 11 is provided as a separate escape path.

  Since the cavity is actually filled with resin at a high pressure, if there is a gas reservoir in the scale, it is considered that it exists at a fairly high pressure. It is considered that the gas escapes through the through hole 11 communicating with the atmosphere through a slight gap between the contact surfaces of the upper and lower molds located between the cavity 4 and the through hole 11. Moreover, since the gas passage to the through hole 11 and the through hole 11 has a lower pressure than the gas accumulated in the cavity 4, the gas naturally escapes to the outside. Therefore, even if the gas is not discharged from the through-hole 11 and remains in the passage on the contact surface reaching the through-hole 11, the gas in the cavity 4 disappears, and the generation of the unfilled region can be suppressed.

  In FIG. 2, the through hole 11 communicates with the atmosphere, but the gas may be forcibly exhausted by directly connecting a vacuum device (exhaust pipe 15, vacuum pump 13, etc.) to the through hole 11.

  In addition, when the occurrence of resin burrs is acceptable, it is also possible to provide an air vent after the dummy cavity in FIG. 2 from the viewpoint of suppressing the occurrence of unfilled regions. With this configuration, the gas generated before the resin reaches the dummy cavity can be released by the air vent, while the gas reservoir that cannot be released by the air vent can be released by the through hole 11. Further, according to this configuration, even if the air vent is clogged with resin, it is possible to perform deaeration through the through hole 11.

  Next, a manufacturing process of a semiconductor device using the resin sealing device 1 will be described.

  First, a semiconductor chip as an object to be sealed is fixed and mounted on a lead frame, each semiconductor chip (not shown) is disposed in a corresponding cavity 4, and the upper mold 2 and the lower mold 3 are brought into contact with each other. Tighten the mold. Here, the packing 12 between the upper mold 2 and the lower mold 3 is compressed, and the contact surface is sealed.

  Next, the vacuum pump 13 is operated to deaerate the resin flow path on the abutting surface, and the pressure is reduced. This is to prevent the occurrence of voids by preventing air from being entrained in the resin injected by exhausting the air to the outside of the mold, and to prevent unfilled defects. Specifically, for example, the process is performed until the vacuum pressure reaches about 5 Torr. Further, the deaeration can be performed by the vacuum pump 23 shown in FIG. In such a case, deaeration is performed through the slight gap between the through hole 11 and the contact surface described above. The lower mold 3, or both the lower mold 3 and the upper mold 2 are heated to a predetermined molding temperature by a heater. The molding temperature varies depending on the resin, and is about 150 ° C., for example.

  In the above description, deaeration is performed after the upper and lower molds are clamped (mold clamp), but other processes are possible. Specifically, before the mold is completely clamped, the mold clamping operation (clamping operation) is temporarily stopped, and the space of the contact surface including the resin flow path is sealed with a sealing member (packing 12) (mold) This may be referred to as a pre-clamp seal), followed by deaeration with a vacuum pump, followed by mold clamping. Here, temporarily stopping the mold clamping operation is to temporarily stop the operation, for example, about 1 mm before complete mold clamping. At this time, the sealing member (packing 12) is compressed by the upper and lower molds. .

  By performing deaeration before mold clamping in this way, air can be easily discharged from the upper and lower molds and the resin tablet, and residual air when the resin flows into the cavity 4 is eliminated. There is an advantage that defects such as a wire flow due to the phenomenon hardly occur. From the above viewpoint, it is preferable to perform seal before mold clamping and deaeration before mold clamping, and then perform resin injection. The packing 12 is an example of a sealing member, and can be sealed with another member.

  Next, the resin tablet 6 is arrange | positioned in the pot 7, and the resin tablet 6 is extruded by the raise of the plunger 5. FIG. And the resin tablet 6 which was initially solid melt | dissolves with the heat | fever of a metal mold | die. The dissolved resin moves from the pot 7 through the cal 8, the gate 9, and the runner 10 and is guided into the cavities 4. When this resin is introduced, air (gas) generated in the resin flow path is excluded to the outside of the cavity through the through hole 11. Further, since there is no air vent directly communicating with the resin flow path as in the prior art, the generation of resin burrs is suppressed. In addition, since a part of the resin does not reach the through hole 11 through the gap of the contact surface other than the resin flow path, no resin burr is generated on the contact surface.

  Next, the reduced pressure state is maintained (for example, for 100 seconds). At this time, the boiling point may be lowered in a reduced pressure state, and a volatile component is generated as a gas during the curing reaction of the resin, but this is also outside the cavity through a slight gap to the through hole 11. It is sucked out by pressure difference.

  Next, the operation of the vacuum pump 13 is released, and then the state is held for a predetermined time (for example, 210 seconds) until the resin is completely cured. The reason why the operation of the vacuum pump 13 is canceled in this way is that the effect of preventing void defects is improved as compared with the case where the operation is not performed until the resin is completely cured. It is unclear what mechanism is effective in preventing this void failure, but the volatile component of the resin that was generated during the resin curing reaction or that is being generated penetrates when the vacuum state is released. It is considered that the air is exhausted to the outside through the hole 11. Moreover, by releasing the vacuum, the boiling point of the gas may rise and the gas may return to a liquid state. Therefore, the generation of voids in the molded product is reduced. The term “until completely cured” refers to a state where the resin is cured to the extent that the state of the resin is maintained when the molded product is separated from the mold.

  Thereafter, the upper mold 2 and the lower mold 3 are separated, the shaped lead frame is taken out and cut for each semiconductor chip, and a final resin-encapsulated semiconductor device is completed.

  As described above, in the resin sealing device of the present invention and the method of manufacturing a semiconductor device using the same, a through-hole that communicates with the outside without being directly connected to the resin flow path is provided. The resin sealing device shown in FIGS. 1 to 3 does not include a conventional air vent that communicates the resin flow path with the outside. Therefore, generation | occurrence | production of the resin burr | flash can be suppressed. In particular, it is also effective for a resin having high fluidity in which the occurrence of resin burrs was remarkable.

  In addition, since it is possible to deaerate during the sealing process through a very small gap and through hole on the contact surface excluding the resin flow path, the resin is guided to each cavity with sufficient fluidity and is not filled. Defects can be prevented. Moreover, generation | occurrence | production of a resin void can be prevented by deaeration of a resin flow path. Furthermore, it becomes possible to reduce the burden of the cleaning operation of the sealing resin device after the sealing step and the appearance inspection step, and the reliability and yield of the completed semiconductor device can be improved.

  Needless to say, the present invention is not limited to the above-described embodiment and can be modified without departing from the scope of the invention. For example, the through hole 11 is provided in the upper mold 2 in the above embodiment, but it may be provided in the lower mold 3.

It is sectional drawing explaining the manufacturing method of the resin sealing device and semiconductor device which concern on embodiment of this invention. It is a top view explaining the upper metal mold | die which concerns on embodiment of this invention. It is sectional drawing explaining the manufacturing method of the resin sealing device and semiconductor device which concern on embodiment of this invention. It is sectional drawing explaining the manufacturing method of the conventional resin sealing device and a semiconductor device. It is a top view explaining the upper metal mold | die which concerns on the conventional resin sealing apparatus.

Explanation of symbols

1 Resin sealing device 2 Upper mold 3 Lower mold 4 Cavity
5 Plunger 6 Resin tablet 7 Pot 8 Pot
9 Gate 10 Runner 11 Through hole 12 Packing
13 Vacuum pump 14 Valve 15 Exhaust pipe 16 Pot connection path 20 Step part 21 Mold base 22 Exhaust pipe 23 Vacuum pump 100 Resin sealing device 101 Upper mold 102 Lower mold
103 Cavity 104 Plunger 105 Resin Tablet 106 Pot 107 Cal 108 Gate 109 Runner 110 Air Vent 111 Packing 112 Pot Connection Path

Claims (6)

A lead frame provided with a semiconductor chip on the surface or a sealed body comprising a support substrate provided with a semiconductor chip on the surface is disposed in a cavity provided on the contact surface between the upper mold and the lower mold,
The contact surface of the upper mold and the lower mold is provided with a resin flow path until a resin-dissolved resin that seals the object to be sealed reaches the cavity. The molten resin is injected into the cavity through the passage with a low viscosity,
A method of manufacturing a semiconductor device that removes the object to be sealed from the cavity after curing of the dissolved resin,
The abutment surface of the upper mold and the lower mold around the cavity has a gap that allows the gas to move although the resin cannot flow, and the upper mold and the lower mold have a gap. A through hole located in the gap of the contact surface is provided in one of the molds,
A method for manufacturing a semiconductor device, characterized in that a gas generated from a dissolved resin introduced into the cavity is discharged to the outside through the gap and the through hole. The method for manufacturing a semiconductor device according to claim 1 , wherein the cavity is not provided with an air vent. The method for manufacturing a semiconductor device according to claim 1, wherein the resin is transparent to light and does not contain a filler. The upper mold and the lower mold are brought into contact with each other, gas in the cavity and the resin flow path is discharged through the gap and the through hole, and then the dissolved resin is injected into the cavity. A method for manufacturing a semiconductor device according to claim 1, claim 2 or claim 3. The semiconductor device manufacturing method according to claim 4, wherein a plurality of cavities are connected in a row through a runner, and a cavity is connected to a cavity at an end of the row. The method for manufacturing a semiconductor device according to claim 1, wherein the support substrate is a flexible sheet, a ceramic substrate, a metal substrate, or a printed substrate.

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