JP3634261B2 - Resin sealing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin sealing device that fills and cures a molten resin in a gap between a flip-chip bonded semiconductor chip and a substrate, and seals the semiconductor chip with a resin.
[0002]
[Prior art]
A conventional case where a gap between a flip-chip bonded semiconductor chip and a substrate is filled with resin and sealed with resin to form a finished product, that is, a package will be described.
In flip-chip resin sealing, molten resin is injected into the cavity in order to perform underfill, that is, to fill the gap formed between the semiconductor chip and the substrate with a bump. Since this gap is only about 30 to 100 μm, the viscosity of the molten resin that has been used so far cannot be sufficiently underfilled. Therefore, a low viscosity resin is injected into the cavity at a low pressure.
[0003]
[Problems to be solved by the invention]
However, the flip chip underfill using the conventional resin sealing has the following problems.
First, in recent years, especially with respect to CPUs, the need for effective cooling of semiconductor chips has increased due to the increase in speed. Therefore, a technique for resin sealing by exposing the back surface of the semiconductor chip is required. Therefore, the entire back surface of the semiconductor chip is pressed using a jig having a surface parallel to the substrate, and a low-viscosity resin is injected into the cavity in this state. However, the semiconductor chip may be tilted and bonded due to variations in the size of the bumps. In this case, if the entire back surface of the semiconductor chip is pressed, there is a problem that the semiconductor chip or the bump may be damaged. In addition, if the semiconductor chip and the bump are pressed to such an extent that they are not damaged, a gap is generated between the jig and the back surface of the semiconductor chip, and there is a possibility that a resin flash is generated on the back surface of the semiconductor chip. Since this resin beam hinders the attachment of the heat sink to the back surface of the semiconductor chip, there is a problem that the assembly yield is lowered.
The resin sealing mold is provided with an air vent with a depth of about several tens of μm for the purpose of shortening the resin filling time and discharging gas for suppressing voids. Therefore, there is a problem that the low-viscosity resin easily leaks from the air vent.
In addition, a resin is injected into a substantially square semiconductor chip from the gate portion provided on the same line as the diagonal line, targeting the corner portion of the semiconductor chip along the diagonal line. However, there is a possibility that the flow of the low-viscosity resin becomes non-uniform due to a slight displacement between the gate portion and the semiconductor chip. In this case, after the low-viscosity resin that has reached the air vent first closes the air vent, bubbles remain in the low-viscosity resin and voids are generated.
Moreover, the resin pressure of low viscosity resin is measured using the sensor incorporated in the plunger. However, since the value including the sliding resistance between the pot and the plunger is measured, there is a problem that when the low-viscosity resin is injected into the cavity at a low pressure, an error occurs in the measured value of the resin pressure. .
[0004]
The present invention has been made in order to solve the above-described problems, and properly presses the back surface of the semiconductor chip to surely expose the back surface, and prevents resin flash, leakage of molten resin and generation of voids. An object of the present invention is to provide a resin sealing device that suppresses the above and accurately measures the resin pressure.
[0005]
[Means for Solving the Problems]
In order to solve the above technical problem, a resin sealing device according to the present invention is a cavity formed of a space including a gap between a semiconductor chip flip-chip bonded to a substrate and the substrate. A resin sealing device for curing a filled molten resin to expose a back surface of a semiconductor chip and resin-sealing the semiconductor chip, and a stretching mechanism for stretching a resin film along the back surface of the semiconductor chip And a pressing mechanism that presses the semiconductor chip when the semiconductor chip is sealed with the resin, and the pressing mechanism is tiltably provided so that the end surface of the pressing mechanism can be tilted and melted. this end face for the purpose of preventing the resin from leaking to the back of the semiconductor chip is provided so as to press the entire surface of the backside of the semiconductor chip through the resin film The features.
[0006]
According to this, even when the semiconductor chip is mounted on the substrate in an inclined manner, the end surface of the pressing mechanism is inclined so that the semiconductor chip is properly pressed, and the back surface of the semiconductor chip and the pressing mechanism are It is suppressed that a gap occurs between them. Accordingly, it is possible to prevent damage to the semiconductor chip and the like, and it is possible to prevent the occurrence of resin flash on the back surface of the semiconductor chip.
[0007]
Further, the resin sealing device according to the present invention fills and cures the molten resin in the gap between the semiconductor chip flip-chip bonded to the substrate and the substrate, and exposes the semiconductor chip by exposing the back surface of the semiconductor chip. A resin sealing device for resin sealing, a stretching mechanism for stretching a resin film along a back surface of a semiconductor chip, a pressing mechanism for pressing the semiconductor chip when the semiconductor chip is sealed with resin, and a semiconductor And a lock mechanism that holds the pressing mechanism so that the semiconductor chip does not float by the pressure of the molten resin that is filled when the chip is sealed with resin.
[0008]
According to this, since the pressing mechanism is held even when the pressure of the molten resin to be filled is applied in the direction of lifting the semiconductor chip when the semiconductor chip is resin-sealed, the semiconductor chip Can be prevented from rising.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. 1A and 1B are cross-sectional views taken along line AA of FIG. 1B, and FIG. 1B is a cross-sectional view of the resin sealing device according to the present embodiment. It is a top view which shows a substrate and a semiconductor chip by drawing a gas flow path virtually.
[0010]
1A and 1B, a lower mold 1 and an upper mold 2 are molds provided so as to face each other, and together constitute a resin sealing mold. The substrate 3 is a wiring member provided with a wiring pattern and placed on the lower mold 1. The semiconductor chip 4 is an integrated circuit such as a CPU. The bumps 5 are protruding electrodes that electrically connect terminals (not shown) of the substrate 3 and the semiconductor chip 4 respectively. The gap 6 is a space of about 30 to 100 μm between the upper surface of the substrate 3 and the lower surface of the semiconductor chip 4. In order to maintain the reliability of the completed package, a sealing resin is uniformly applied to the gap. Need to be filled. The substrate pressing members 7A and 7B are provided so as to be movable up and down, and are pressing members that fix the substrate 3 when lowered. The cavity 8 is a space surrounded by the upper surface of the substrate 3, the substrate pressing members 7 </ b> A and 7 </ b> B, and the upper mold 2, and into which low viscosity resin is injected.
[0011]
The pot 9 is a cylindrical space provided in the lower mold 1. The plunger 10 is a cylindrical pressing mechanism that is provided below the pot 9 so as to be movable up and down. The resin tablet 11 is a cylindrical resin material that is put into the pot 9 and is made of, for example, an epoxy resin and melted to be a raw material for the low-viscosity resin.
[0012]
The cull portion 12 is a recess provided in the upper mold 2 so as to face the pot 9. The cull part 12, the runner part 13, and the gate part 14 are resin flow parts in which a low-viscosity resin flows in a space that sequentially communicates from the cull part 12 to the cavity 8. Here, as shown in FIG. 1B, the gate portion 14 has the center line of the gate portion 14 substantially perpendicular to one side of the semiconductor chip 4 when the semiconductor chip 4 is viewed in plan. And it is provided so as to pass through the midpoint. The air vent 15 is a gas flow path provided substantially symmetrically with the gate portion 14 with respect to the center line of the semiconductor chip 4. That is, the center line of the gate portion 14, the center line of the air vent 15, and the center line passing through one side in the semiconductor chip 4 are substantially overlapped.
The movable member 16 is an open / close valve for the air vent 15 that can be moved up and down at the boundary between the cavity 8 and the air vent 15. Here, the movable member 16 is driven by, for example, an air cylinder, a linear motor, or the like, and can set an opening / closing timing, an opening amount, and a pressing force at the closing time. The resin film 17 is a release film that is stretched along the mold surface of the upper mold 2 and the upper surface of the chip pressing member 7B so as to be in close contact with the back surface of the semiconductor chip 4 in a mold-clamped state.
[0013]
Hereinafter, the operation of the resin sealing device according to the present embodiment will be described with reference to FIGS. 2 and 3. FIGS. 2A and 2B respectively show the behavior of the low-viscosity resin immediately after the resin sealing device according to the present embodiment starts injecting the resin, and FIG. Sectional drawing shown along A line, (b) is a top view which shows the board | substrate and a semiconductor chip by drawing the flow path of low-viscosity resin and gas virtually. 3A and 3B show the state of the resin sealing device according to this embodiment, FIG. 3A shows a state immediately before the low-viscosity resin injection is finished, and FIG. 3B shows the low-viscosity resin injection. It is sectional drawing which shows the state immediately after complete | finishing.
[0014]
First, as shown in FIG. 2A, the movable member 16 is raised to open the air vent 15. In this state, the resin tablet 11 is heated and melted by a heater (not shown) provided in the mold to form the low viscosity resin 18. Then, the low-viscosity resin 18 is pressed by the plunger 10, the low-viscosity resin 18 is branched at the cull portion 12, and injected into the cavity 8 through the runner portion 13 and the gate portion 14 in order.
[0015]
In the process so far, as shown in FIG. 2B, the gas (gas) in the cavity 8 is discharged out of the mold through the air vent 15 (see thick solid arrows).
The center line of the gate portion 14 is provided so as to pass substantially perpendicular to one side of the semiconductor chip 4 and through its midpoint. Thereby, the low-viscosity resin 18 injected from the gate 14 is not covered with the semiconductor chip 4 on the substrate 3, that is, in the exposed portion of the substrate 3, the semiconductor chip 4 is directed toward the side where the air vent 15 is provided. It flows almost evenly along the side. In the gap 6, since the gas is discharged from the air vent 15, the low-viscosity resin 18 flows toward the air vent 15 side at a slightly lower speed than the exposed portion of the substrate 3 (see the broken arrow). . Therefore, even when a positional deviation occurs between the gate portion 14 and the semiconductor chip 4, the low-viscosity resin 18 flows almost uniformly and fills the cavity 8 without leaving bubbles, so that voids are generated. Can be suppressed.
[0016]
Next, as shown in FIG. 3A, the low viscosity resin 18 is continuously pressed by the plunger 10 and injected into the cavity 8. Here, at a timing immediately before the cavity 8 is filled, the movable member 16 is lowered and the air vent 15 is closed. Thereby, leakage of the low-viscosity resin 18 to the air vent 15 can be suppressed.
[0017]
Through the above steps, the cavity 8 is filled with the low viscosity resin 18 as shown in FIG. In this state, the low-viscosity resin 18 is subsequently heated and cured to form a cured resin, and the resin sealing is completed. Thereafter, the lower mold 1 and the upper mold 2 are opened, and the substrate pressing member 7A is raised to perform a gate break, thereby completing a package made of the substrate 3, the semiconductor chip, and the cured resin.
[0018]
As described so far, according to the present embodiment, the gas in the cavity 8 is discharged out of the mold via the air vent 15 as shown in FIGS. In addition, even when a positional deviation occurs between the gate portion 14 and the semiconductor chip 4, the low-viscosity resin 18 flows almost uniformly and fills the cavity 8 without leaving bubbles. Therefore, generation of voids can be suppressed.
Further, as shown in FIG. 3A, the movable member 16 is lowered to close the air vent 15 at a timing immediately before the cavity 8 is filled. Therefore, leakage of the low viscosity resin 18 to the air vent 15 can be suppressed.
As shown in FIG. 1A, the resin film 17 is stretched in close contact with the back surface of the semiconductor chip in a state where the mold is clamped. Therefore, it is possible to improve the releasability when the mold is opened after the low-viscosity resin 18 is cured and to prevent resin flash on the back surface of the semiconductor chip 4.
[0019]
In the present embodiment, the back surface of the semiconductor chip 4 is exposed. This embodiment is not limited to this, and the present embodiment can also be applied to the case where the semiconductor chip 4 is entirely covered with the low-viscosity resin 18 without exposing the back surface of the semiconductor chip 4.
It is also possible to adopt a configuration in which the resin film 17 is not provided.
[0020]
In this embodiment, the low-viscosity resin 18 can be injected into the cavity 8 while sucking the atmosphere in the cavity 8 from the outside via the air vent 15. In this case, since the low-viscosity resin 18 quickly enters the gap 6, the low-viscosity resin 18 flows toward the air vent 15 at substantially the same speed between the exposed portion of the substrate 3 and the gap 6. Therefore, the cavity 8 can be filled in a short time.
Furthermore, in this case, since the atmosphere in the cavity 8 is sucked, even if bubbles remain in the low-viscosity resin 18 filled in the cavity 8, the inside of the bubbles is at a low pressure. . Accordingly, the remaining bubbles are crushed to a small extent by the pressure of the low-viscosity resin 18 so as not to cause a problem.
[0021]
(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. 4A and 4B show the resin sealing device according to the present embodiment. FIG. 4A shows a state where the semiconductor chip is bonded in parallel to the substrate, and FIG. 4B shows that the semiconductor chip is inclined to the substrate. It is sectional drawing which shows the state by which each was bonded.
[0022]
4A and 4B, the chip pressing member 19 is a pressing member that is provided below the lifting shaft 20 and presses the semiconductor chip 4 along its back surface. The elevating shaft 20 is an elevating mechanism that is provided so as to freely move up and down and operates so that the chip pressing member 19 presses the semiconductor chip 4 with a predetermined pressure. The ball bearing 21 is a bearing that is provided between the chip pressing member 19 and the elevating shaft 20 and slides the chip pressing member 19 smoothly.
[0023]
As shown in FIG. 4B, when the semiconductor chip 4 is tilted and bonded to the substrate 3 due to variations in the size of the bumps 5, the chip pressing member 19 is tilted by the ball bearing 21 and The semiconductor chip 4 is pressed along Thereby, the whole back surface of the semiconductor chip 4 can be pressed without gaps without damaging the semiconductor chip 4 and the bumps 5.
[0024]
As described above, according to the present embodiment, damage to the semiconductor chip 4 and the bumps 5 can be prevented. Further, there is no gap between the back surface of the semiconductor chip 4 and the chip pressing member 19, and the low-viscosity resin 18 does not enter between the upper mold 2 and the chip pressing member 19 by using the resin film 17. . Thereby, the occurrence of resin flash on the back surface of the semiconductor chip 4 is prevented, and the back surface of the semiconductor chip 4 is reliably exposed. Therefore, when a heat sink is attached to the back surface of the semiconductor chip 4, it is possible to suppress a decrease in assembly yield. Thus, the assembly yield can be kept good in the package production process and the heat sink mounting process.
[0025]
(Third embodiment)
A third embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a cross-sectional view showing the configuration of the resin sealing device according to the present embodiment. In FIG. 5, the substrate pressing member 22 is a pressing member that is provided so as to be movable up and down, like the substrate pressing member 7A, and fixes the substrate 3 when lowered. The lock mechanism 23 is a brake mechanism that is provided above the elevating shaft 20 and has a brake pad 24 inside that can clamp the elevating shaft 20 as necessary in a state where the mold is clamped. An air cylinder (not shown) is provided above the lifting shaft 20 and presses the resin film 17 against the back surface of the semiconductor chip 4 with a necessary and sufficient constant force.
[0026]
As described above, according to the present embodiment, an excessive pressure is not applied to the semiconductor chip 4 and the bump 5 in a normal state. In addition, in the case of injecting the low-viscosity resin into the cavity 8 after clamping, when the pressure of the injected low-viscosity resin is applied in the direction to lift the semiconductor chip 4, the brake pad 24 sandwiches the lifting shaft 20. Therefore, the floating of the semiconductor chip 4 can be suppressed.
[0027]
A pressure sensor and a control unit (both not shown) may be provided above the lifting shaft 20. The pressure sensor detects the pressure received when the chip pressing member 19 presses the semiconductor chip 4. Then, the control unit controls the brake pad 24 according to the detected pressure, and the brake pad 24 comes into pressure contact with the lifting shaft 20 sandwiched by the pressure according to the detected pressure.
According to this, when the pressure of the injected low-viscosity resin is applied in a direction to lift the semiconductor chip 4, the brake pad 24 presses the lifting shaft 20 in accordance with the pressure. As a result, since the semiconductor chip 4 is pressed according to the pressure applied in the direction in which the semiconductor chip 4 is lifted, the floating of the semiconductor chip 4 can be suppressed.
[0028]
FIGS. 6A and 6B are cross-sectional views showing configurations of two modified examples of the resin sealing device according to the present embodiment. In FIG. 6A, the chip pressing member 25 has a protruding outer peripheral pressing portion 26 provided continuously or intermittently in the outer peripheral portion, and a through hole 27 in the inner concave portion. The through hole 27 is a gas flow path for discharging the gas between the chip pressing member 25 and the semiconductor chip 4. According to this modification, the outer peripheral portion is appropriately pressed on the back surface of the semiconductor chip 4 without applying excessive pressure to the semiconductor chip 4 and the bumps 5. As a result, on the back surface of the semiconductor chip 4, the portion where the low-viscosity resin is desired to be prevented, that is, the outer peripheral portion of the semiconductor chip 4 is appropriately pressed. Therefore, on the back surface of the semiconductor chip 4, it is possible to suppress the entry of the low-viscosity resin and prevent the occurrence of resin flash.
[0029]
By the way, the chip size tends to increase due to the recent multifunctionalization of semiconductor chips. For this reason, when the low-viscosity resin is injected, the central portion of the semiconductor chip 4 is lifted by the pressure of the injected low-viscosity resin, and electrical connection between the terminals of the semiconductor chip 4 and the bumps 5 and the pads of the substrate 3 is performed. May become unstable.
In another modification shown in FIG. 6B, the chip pressing member 25 further has a projecting center pressing portion 28 at the center. Therefore, in addition to the modification of FIG. 6A, the floating near the center of the semiconductor chip 4 due to the pressure of the injected low viscosity resin can be more effectively suppressed.
[0030]
In the present embodiment, that is, in the configuration shown in FIGS. 5 and 6, the resin film 17 is used. Not limited to this, the chip pressing members 19 and 25 may directly press the back surface of the semiconductor chip 4 without using the resin film 17.
Further, in the configuration shown in FIG. 6, the brake mechanism 23 of FIG. 5 may not be used. Further, the ball bearing 21 of FIG. 4 may be used in combination with the chip pressing members 19 and 25 of FIGS.
[0031]
(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIG. FIGS. 7A and 7B are cross-sectional views showing the configuration of the resin sealing device according to the present embodiment, FIG. 7A showing the configuration thereof, and FIG. 7B showing the state immediately after the start of resin injection. .
[0032]
In FIG. 7A, the fixing member 29 is a block provided in the recess of the upper mold 2 in the runner portion 13. The sensor 30 is pressure detection means provided at the end of the fixing member 29. In a normal state, the pressure detection surface of the sensor 30 is kept flush with the mold surface of the upper mold 2. Thereby, as shown in FIG. 7B, the sensor 30 detects the pressure of the low viscosity resin 18 through the resin film 17.
[0033]
In the present embodiment, the back surface of the semiconductor chip 4 is exposed. This embodiment is not limited to this, and the present embodiment can also be applied to the case where the semiconductor chip 4 is entirely covered with the low-viscosity resin 18 without exposing the back surface of the semiconductor chip 4.
[0034]
According to the present embodiment, when the low viscosity resin 18 is injected into the cavity 8, the sensor 30 is pressed by the low viscosity resin 18 through the resin film 17. Thereby, the resin pressure of the low-viscosity resin 18 can be accurately measured without being affected by the sliding resistance between the pot 9 and the plunger 10.
[0035]
It should be noted that the present invention is not limited to the above-described embodiments, and can be arbitrarily changed, selected, and combined as necessary within the scope not departing from the gist of the present invention. It is.
[0036]
【The invention's effect】
According to the present invention, it is possible to suppress leakage of the molten resin into the air vent and generation of voids in the molten resin filled in the cavity. Further, since the semiconductor chip is properly pressed, the back surface can be surely exposed and damage to the semiconductor chip or the like can be prevented. Moreover, it is possible to prevent the occurrence of resin flash on the back surface of the semiconductor chip. Furthermore, the resin pressure of the molten resin can be accurately measured.
Therefore, the present invention properly measures the resin pressure by properly pressing the back surface of the semiconductor chip to surely expose the back surface and preventing resin flash, suppressing leakage of molten resin and generation of voids. This provides an excellent practical effect that a resin sealing device can be provided.
[Brief description of the drawings]
1A is a cross-sectional view of a resin sealing device according to a first embodiment of the present invention, taken along line AA in FIG. 1B, and FIG. 1B is a low-viscosity resin and gas; FIG. 3 is a plan view showing a substrate and a semiconductor chip by virtually drawing a flow path of FIG.
FIGS. 2A and 2B show the behavior of a low-viscosity resin immediately after the resin sealing device according to the first embodiment of the present invention starts injecting the resin, respectively. FIG. FIG. 5B is a plan view showing a substrate and a semiconductor chip by virtually drawing a low-viscosity resin and gas flow path.
FIGS. 3A and 3B show the state of the resin sealing device according to the first embodiment of the present invention, in which FIG. 3A shows a state immediately before the injection of the low-viscosity resin is completed, and FIG. It is sectional drawing which shows each of these states.
FIGS. 4A and 4B show a resin sealing device according to a second embodiment of the present invention, in which FIG. 4A shows a state in which a semiconductor chip is bonded in parallel to the substrate, and FIG. It is sectional drawing which shows each state.
FIG. 5 is a cross-sectional view showing a configuration of a resin sealing device according to a third embodiment of the present invention.
FIGS. 6A and 6B are cross-sectional views illustrating configurations of two modified examples of the resin sealing device according to the third embodiment of the present invention. FIGS.
7A is a cross-sectional view showing a configuration of a resin sealing device according to a fourth embodiment of the present invention, and FIG. 7B is a cross-sectional view showing a state immediately after resin injection is started.
[Explanation of symbols]
1 Lower mold 2 Upper mold 3 Substrate 4 Semiconductor chip 5 Bump 6 Gap 7A, 7B, 22 Substrate pressing member 8 Cavity 9 Pot 10 Plunger 11 Resin tablet 12 Cal part 13 Runner part 14 Gate part 15 Air vent 16 Movable member (open / close valve)
17 Resin film 18 Low viscosity resin 19 Chip pressing member (pressing mechanism)
20 Lifting shaft 21 Ball bearing 23 Lock mechanism 24 Brake pad 25 Chip pressing member 26 Outer periphery pressing portion 27 Through hole 28 Center pressing portion 29 Fixing member 30 Sensor

Claims (2)

In a cavity including a space including a gap between a semiconductor chip flip-chip bonded to a substrate and the substrate, the molten resin filled from the outside of the cavity is cured to expose the back surface of the semiconductor chip and A resin sealing device for resin sealing a semiconductor chip,
A stretching mechanism for stretching a resin film along the back surface of the semiconductor chip;
While having a pressing mechanism for pressing the semiconductor chip when resin-sealing the semiconductor chip,
The pressing mechanism is provided so as to be tiltable so that an end surface of the pressing mechanism can be tilted, and the end surface is provided with the resin for the purpose of preventing the molten resin from leaking to the back surface of the semiconductor chip. A resin sealing device, which is provided so as to press the entire back surface of the semiconductor chip through a film. A resin sealing device that fills and cures a molten resin in a gap between a semiconductor chip flip-chip bonded to a substrate and the substrate, exposes the back surface of the semiconductor chip, and seals the semiconductor chip with a resin. And
A stretching mechanism for stretching a resin film along the back surface of the semiconductor chip;
A pressing mechanism for pressing the semiconductor chip when resin-sealing the semiconductor chip;
A resin sealing device, comprising: a lock mechanism that holds the pressing mechanism so that the semiconductor chip does not float by the pressure of the molten resin that is filled when the semiconductor chip is resin-sealed.

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