JP2014215278A - Sealing sheet attachment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately attach a sealing sheet to a semiconductor element formed on a semiconductor substrate.SOLUTION: A sealing sheet formed by disposing release liners in a sealing layer is attached to a semiconductor substrate while adding heat and pressure to the sheet, to obtain a temporary crimped state. In this state, the semiconductor substrate is exposed to an X ray, to obtain a transmission image. Whether or not there are voids is inspected from the transmission image and the locations of the voids are determined; and after forming a discharge flow path by sticking a needle for each void, the discharge flow path is repaired while removing the voids by adding heat and pressure to the sealing sheet again. If voids are not detected after re-inspection, the sealing layer is hardened, to be completely crimped to the semiconductor substrate.

Description

  The present invention relates to a sealing sheet attaching method for attaching and sealing a sealing sheet on which a sealing layer made of a resin composition is formed on a plurality of semiconductor elements formed on a semiconductor substrate.

  After surrounding one semiconductor chip with a frame, each of both surfaces of the semiconductor chip is sandwiched between a first sealing resin sheet and a second sealing resin sheet made of a prepreg impregnated with resin. A semiconductor device is manufactured by sealing a semiconductor chip (see Patent Document 1).

JP-A-5-291319

  However, the above conventional method has the following problems.

  That is, in recent years, semiconductor devices tend to be miniaturized due to the demand for high-density mounting accompanying rapid development of applications. Therefore, after the semiconductor wafer is divided into semiconductor elements by the dicing process, the semiconductor elements are individually sealed with resin, resulting in a problem that throughput is lowered and production efficiency is lowered.

  This invention is made | formed in view of such a situation, Comprising: The main objective is to provide the sealing sheet sticking method and sealing sheet sticking apparatus which can stick a sealing sheet to a semiconductor substrate accurately. And

  Therefore, the present inventors have obtained the following knowledge as a result of intensive studies by repeating experiments and simulations in order to solve the inconvenience.

  An attempt was made to divide into a semiconductor device after a single-sheet sealing sheet on which a sealing layer made of a resin composition was formed was applied to the entire surface of the semiconductor substrate and cured.

  However, when a large-area sealing sheet that simultaneously seals a plurality of semiconductor elements is attached to a semiconductor substrate as compared to sealing a single semiconductor element, the adhesive interface between the sealing layer and the semiconductor substrate is used. There was a problem that voids were easily generated, resulting in product defects.

  In order to achieve such an object, the present invention has the following configuration.

That is, a sealing sheet attaching method for attaching a sealing sheet formed with a sealing layer made of a thermoplastic resin composition to a semiconductor substrate,
At least the sealing layer is cut to the shape of the semiconductor substrate or less, and a pasting process for pasting the semiconductor substrate while heating and pressing the sealing sheet in which a release liner is attached to the sealing layer;
An imaging process for acquiring a transmission image by blasting X-rays onto the semiconductor substrate to which the sealing sheet is attached;
Inspecting the presence or absence of voids from the transmission image, an inspection process for obtaining the position of the voids,
It is provided with.

  (Operation / Effect) According to this method, it is possible to detect voids generated by bubbles entrained in the sealing layer, the semiconductor substrate, and the sealing layer after the sealing sheet is attached to the semiconductor substrate. By obtaining the position of the void detection site, the semiconductor element at the site can be appropriately handled in a later step.

That is, in the above method, based on the void position obtained in the inspection process, the needle is pierced to the void of the sealing layer to form the discharge flow path, and then the void is removed by reheating and pressurizing the sealing sheet. While repairing the discharge flow path,
A final pressure bonding process in which the sealing sheet from which voids have been removed in the repair process is cured and finally pressure bonded to the semiconductor substrate;
It is preferable to provide.

  When the sealing layer is subjected to main pressure bonding, depending on the properties of the resin composition forming the sealing layer, the resin composition is heated to 120 to 150 ° C., for example, in order to thermally cure the resin composition. At this time, if the pressure bonding is performed without removing the voids, the voids thermally expand and the sealing layer is ruptured or the semiconductor element is damaged.

  However, according to this method, the sealing layer is not cured when the sealing sheet is attached to the semiconductor substrate. Therefore, the needle can be easily pierced to the void of the sealing layer. Therefore, it is possible to remove the void from the sealing layer and soften the resin composition to block the discharge flow path by reheating and pressurizing with the needle inserted into the void to form the air discharge flow path. Can do. Therefore, after removing the void from the sealing layer, it is possible to perform the main landing, so that it is possible to avoid defects such as breakage of the sealing layer.

  In the above method, it is more preferable to remove the void from the sealing layer while reducing the pressure in the reduced pressure chamber. According to this method, voids in the sealing layer can be reliably removed.

  According to the sealing sheet attaching method of the present invention, the adhesive interface between the sealing layer of the sealing sheet attached to the semiconductor substrate and the semiconductor substrate and voids generated in the sealing layer are detected, and the detection result is Based on this, voids can be removed.

It is a perspective view which shows the original fabric roll of a sealing sheet. It is a longitudinal cross-sectional view of a sealing sheet. It is a flowchart which shows the operation | movement which affixes a sealing sheet on a semiconductor substrate. It is a front view which shows the cutting | disconnection operation | movement of the sealing sheet in a cutting process. It is a front view which shows the cutting | disconnection operation | movement of the sealing sheet in a cutting process. It is a front view which shows the cutting | disconnection operation | movement of the sealing sheet in a cutting process. It is a front view which shows peeling operation | movement of a 2nd peeling liner. It is a front view which shows peeling operation | movement of a 2nd peeling liner. It is a front view which shows alignment with a semiconductor substrate and a sealing sheet piece. It is a front view which shows the sticking operation | movement of a sealing sheet. It is a front view of the semiconductor substrate in an inspection process. It is a top view which shows the permeation | transmission image of a semiconductor substrate. It is a front view which shows the operation | movement of restoration. It is a front view which shows the operation | movement of restoration. It is a front view which shows the operation | movement of restoration. It is a front view which shows the operation | movement of restoration. It is a front view which shows the inspection apparatus of a modification.

  An embodiment of the present invention will be described below with reference to the drawings. A case where a sealing sheet having a sealing layer made of a resin composition is attached to a semiconductor substrate having a plurality of semiconductor elements formed on the surface will be described as an example.

<Sealing sheet>
For example, as shown in FIGS. 1 and 2, the sealing sheet T is supplied by being cut into a sheet-shaped body having a predetermined shape from an original roll or a raw roll in which a long sealing sheet T is wound. The Further, the sealing sheet T is provided with a protective first release liner S1 and a second release liner S2 on both surfaces of the sealing layer M.

  The sealing layer M is formed in a sheet shape from a sealing material. Examples of the sealing material include thermosetting silicone resin, epoxy resin, thermosetting polyimide resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, thermosetting urethane resin, and the like. A curable resin is mentioned. Moreover, as a sealing material, the above-mentioned thermosetting resin and the thermosetting resin composition which contains an additive in an appropriate ratio can also be mentioned.

Examples of the additive include a filler and a phosphor. Examples of the filler include inorganic fine particles such as silica, titania, talc, alumina, aluminum nitride, and silicon nitride, and organic fine particles such as silicone particles. The phosphor has a wavelength conversion function, and examples thereof include a yellow phosphor capable of converting blue light into yellow light, and a red phosphor capable of converting blue light into red light. . Examples of the yellow phosphor include garnet phosphors such as Y ₃ Al ₅ O ₁₂ : Ce (YAG (yttrium, aluminum, garnet): Ce). Examples of the red phosphor include nitride phosphors such as CaAlSiN ₃ : Eu and CaSiN ₂ : Eu.

  The sealing layer M is adjusted to a semi-solid state before sealing the semiconductor element. Specifically, when the sealing material contains a thermosetting resin, for example, complete curing (C It is adjusted before being staged, that is, in a semi-cured (B stage) state.

  The dimension of the sealing layer M is appropriately set according to the dimensions of the semiconductor element and the substrate. Specifically, when the sealing sheet is prepared as a long sheet, the length in the left-right direction of the sealing layer, that is, the width is, for example, 100 mm or more, preferably 200 mm or more, for example, 1500 mm. Hereinafter, it is preferably 700 mm or less. The thickness of the sealing layer is appropriately set according to the size of the semiconductor element, and is, for example, 30 μm or more, preferably 100 μm or more, and for example, 3000 μm or less, preferably 1000 μm or less.

  Examples of the first release liner S1 and the second release liner S2 include polymer sheets such as polyethylene sheets, polyester sheets (such as PET), polystyrene sheets, polycarbonate sheets, and polyimide sheets, such as ceramic sheets, such as metal foil. It is done. In the release liner, the contact surface in contact with the sealing layer can be subjected to a release treatment such as a fluorine treatment. The dimensions of the first release liner and the second release liner are appropriately set according to the release conditions, and the thickness is, for example, 15 μm or more, preferably 25 μm or more, and for example, 125 μm or less, preferably 75 μm. It is as follows.

  <Sealing sheet pasting method>

  A case where a single-sheet sealing sheet piece cut out in a predetermined shape from the roll-shaped sealing sheet is attached to a semiconductor substrate will be described with reference to the flowchart shown in FIG. 3 and FIGS. 4 to 16.

  First, as shown in FIG. 4, the back surface of the strip-shaped sealing sheet T supplied from the raw fabric roll is adsorbed and held by the holding member 1 in the cutting step. Note that the holding member 1 is constituted by a chuck table larger than the semiconductor substrate W, for example.

  As shown in FIG. 5, the sealing sheet T with the back surface held by suction is cut into the shape of the semiconductor substrate W by the annular Thomson blade 2 having the same diameter as the outer shape (diameter) of the semiconductor substrate W (step S1). . The cutting blade is not limited to the annular Thomson blade 2, and the sealing sheet T may be cut into the shape of the semiconductor substrate W by piercing and turning a tapered taper cutter.

  When the cutting process is completed, the suction plate 4 of the sheet transport mechanism 3 sucks the sealing sheet T on the holding member 1 and rises. At this time, the sealing sheet piece CT cut into the semiconductor substrate-shaped sheet is extracted from the band-shaped sealing sheet T.

  Sealing sheet piece CT is conveyed to a peeling process. In this conveyance process, the sealing sheet piece CT held by the suction plate 4 is imaged by the imaging camera 5 as shown in FIG. 6, and the image data is transmitted to the control unit 6. The control part 6 calculates | requires the center coordinate of sealing sheet piece CT from the said image data (step S2).

  When the sealing sheet piece CT reaches the peeling position in the peeling process, the peeling roller 8 rises. That is, as shown in FIG. 7, the peeling tape TS wound around the peeling roller 8 is pressed against the second peeling liner S2 on the back surface side of the sealing sheet piece CT as indicated by a chain line. Thereafter, as shown in FIG. 8, the second release liner S2 is peeled from the sealing sheet piece CT while winding the release tape TS at a speed synchronized with the transport speed of the sheet transport mechanism 3. The peeled second peeling liner S2 is wound and collected on the collecting bobbin 9 together with the peeling tape TS (step S3).

  The sealing sheet piece CT from which the second release liner S2 has been peeled is transported to the attaching step by the sheet transport mechanism 3. That is, the sealing sheet piece CT is conveyed onto the first holding table 10 on which the semiconductor substrate W is held by suction.

  The semiconductor substrate W on the first holding table 10 is as shown in FIG. 9 based on the image data of the sealing sheet piece CT acquired in the conveyance process and the center coordinates of the semiconductor substrate W acquired in advance. Then, alignment is performed by rotating the first holding table 10 around the horizontal and vertical axes so that the center coordinates of the sealing sheet piece CT and the semiconductor substrate W coincide (step S4).

  When the alignment process is completed, the sealing plate piece CT is heated to a predetermined temperature by heating the suction plate 4 with the embedded heater 11. Thereafter, as shown in FIG. 10, the suction plate 4 is lowered to a predetermined height, so that the sealing sheet piece CT is attached to the semiconductor substrate W while being heated and pressurized (step S5).

  At this time, the resin composition forming the sealing layer M is softened by heating and enters between a plurality of adjacent semiconductor elements C formed on the semiconductor substrate W to remove air while removing the semiconductor elements. C is sealed.

  The resin composition is heated and semi-cured over a predetermined time in a constant pressure state. That is, the sealing sheet piece CT is temporarily pressure-bonded to the semiconductor substrate W. When the predetermined time has elapsed, the suction of the first holding table 10 is stopped. The semiconductor substrate W is sucked and held by the suction plate 4 and transferred to the inspection process.

  The semiconductor substrate W is placed on the top plate 16 of the inspection stage. As shown in FIG. 11, the X-ray tube 17 and the X-ray detector 18 are disposed opposite to each other with the top plate 16 interposed therebetween. Therefore, X-rays that have been blasted from the X-ray tube 17 and transmitted through the semiconductor substrate W are detected by the X-ray detector 18 (step S6). Based on the transmitted X-ray, a transmission image inside the sealing layer M is acquired as shown in FIG. As the X-ray detector 18, for example, a flat panel X-ray detector in which detection elements are arranged in a two-dimensional array is used.

  The control unit 6 determines the void 19 from the acquired transmission image and obtains the position coordinates of the void 19. When the X-ray imaging is completed, the semiconductor substrate W is sucked and held by the suction plate 4 of the sheet transport mechanism 3 and transported to the repair process.

  The semiconductor substrate W is placed on the second holding table 20. The control unit 6 moves the needle 25 to the position of the void 19 based on the position coordinates of the void 19 obtained in the inspection process. For example, as shown in FIG. 13, the needle 25 is connected to a lower end of a support arm 22 connected to a horizontally movable table 21 via a folder 24 attached to a movable table 23 that moves up and down along the support arm 22. And is detachably equipped. As shown in FIG. 14, the controller 6 lowers the needle 25 to a predetermined height and pierces the tip of the needle 25 into the void 19 of the sealing layer M. By pulling out the pierced needle 25 from the sealing layer M, a discharge channel 26 is formed to discharge the air in the void 19. At this time, since the heights of the semiconductor substrate W and the semiconductor element C are determined in advance, the descending height of the needle 25 is changed according to the generation site of the void 19.

  When the needle 25 is completely pierced by the void 19, the needle 25 returns to the upper standby position. Thereafter, the second holding table 20 housed in the lower housing 30a constituting the decompression chamber 30 moves to below the upper housing 30b as shown in FIG. The decompression chamber 30 is configured to be lowered until the lower end of the upper housing 30b comes into contact with the upper end of the lower housing 30a.

  As shown in FIG. 16, the controller 6 depressurizes the inside of the decompression chamber 30 and lowers the pressing plate 32 in which the heater 31 is embedded to pressurize the sealing sheet piece CT while heating it at a predetermined temperature. At this time, air is extracted from the discharge flow path 26, and the void 19 and the discharge flow path 26 are filled with the resin composition that has been softened simultaneously with the discharge (step S7).

  When the repair process is completed, the pressing plate 32 and the upper housing 30b are raised, and the lower housing 30a is moved to the delivery position of the semiconductor substrate W. The semiconductor substrate W is transported again to the inspection process by the suction plate 4 of the sheet transport mechanism 3. If the void 19 is not detected in the sealing layer M as a result of the inspection, it is transported to the second holding table 20 and the sealing sheet piece CT is finally bonded to the semiconductor substrate W in the decompression chamber 30. At this time, the sealing layer M has been hardened more than the temporary pressure bonding, but is not completely cured.

  As for 1st peeling liner S1 of sealing sheet piece CT, the adhesive force of the sealing layer M is falling. Accordingly, the first release liner S1 can be easily peeled from the sealing layer M by suctioning the semiconductor substrate W by the second holding table 20 and ascending the first release liner S1 by the suction plate 4. (Step S8).

  The semiconductor substrate W sealed with the semiconductor element C by the sealing layer M is transported to a desired processing step, and a series of pasting processes is completed.

  According to the above embodiment, when the void 19 is detected in the sealing layer M at the time when the sealing sheet piece CT is temporarily bonded to the semiconductor substrate W, the void 19 can be removed. That is, in the repair process, the needle 25 is pierced to the void 19 in the semi-cured sealing layer M to form the air discharge channel 26. While the semiconductor substrate W on which the discharge channel 26 is formed is put into the decompression chamber 30 and decompressed, the pressure sheet 32 is pressurized while heating the sealing sheet piece CT. As a result, air is extracted from the void 19 of the sealing layer M, and the void 19 and the discharge flow path 26 are filled with the softened resin composition.

  Therefore, it is possible to avoid the rupture of the sealing layer M and the damage of the semiconductor element C caused by the void 19.

  In addition, this invention can also be implemented with the following forms.

  (1) In the above embodiment, a transmission image obtained by bombarding the semiconductor substrate W with X-rays may be used as a live image. That is, the void 19 may be pierced while monitoring the tip of the needle 25 that pierces the sealing layer M.

  In the above embodiment, as shown in FIG. 17, the X-ray tube 17 and the X-ray detector 18 are opposed to each other in an inclined posture with the top plate 16 interposed therebetween, and the X-ray tube 17 and the X-ray detector 18 are arranged. The transmitted X-rays of the semiconductor substrate W may be acquired from a plurality of angles by relatively rotating the set 16 and the top plate 16 around the vertical axis. In the case of this configuration, the height of the void 19 can also be obtained using transmission images acquired from a plurality of angles.

  Therefore, by adjusting the piercing height of the needle 25 according to the height, the tip of the needle 25 can be accurately pierced into the void 19 without damaging the semiconductor element C.

  (2) In the above embodiment, when the semiconductor substrate W is transported to the inspection process at the time of provisional pressure bonding, the first holding table 10 is used instead of the suction plate 4 of the sheet transport mechanism 3, and the pasting process and the inspection process are performed. You may reciprocate. In this case, the first holding table 10 may be made of a material that transmits X-rays such as carbon.

  (3) In the said Example, you may comprise so that the load concerning the semiconductor substrate W at a sticking process may be measured with a load sensor, and a load may be adjusted. For example, at least one of the suction plate 4 and the first holding table 10 includes a load sensor. In the process of repairing the sealing layer M, the control unit 6 compares the actual value detected by the load sensor with a predetermined reference value. If the actual value exceeds the reference value, the lowering speed of the suction plate 4 is reduced. It is configured to keep the load constant.

  According to this configuration, the flow rate of the resin composition softened (plastically deformed) by heating radially spreading on the semiconductor substrate W can be integrally maintained. That is, the resin composition can be prevented from protruding from the semiconductor substrate W due to a rapid flow.

  (4) In the above embodiments, the shape of the semiconductor substrate W is not limited to a circle. Therefore, the semiconductor substrate W may be a quadrangle such as a square or a rectangle or a polygon. In this case, the sealing sheet piece CT may be a square or a polygon such as a square or a rectangle according to the shape of the semiconductor substrate W.

DESCRIPTION OF SYMBOLS 1 ... Holding member 2 ... Thomson blade 3 ... Sheet conveyance mechanism 4 ... Suction plate 6 ... Control part 8 ... Peeling roller 10 ... 1st holding table 11 ... Heater 17 ... X-ray tube 18 ... X-ray detector 20 ... 2nd holding | maintenance Table 23 ... Needle 30 ... Decompression chamber 31 ... Heater 32 ... Press plate T ... Sealing sheet CT ... Sealing sheet piece C ... Semiconductor element M ... Sealing layers S1, S2 ... First and second release liners W ... Semiconductor substrate

Claims (3)

A sealing sheet affixing method for affixing a sealing sheet formed with a sealing layer made of a thermoplastic resin composition to a semiconductor substrate,
At least the sealing layer is cut to the shape of the semiconductor substrate or less, and a pasting process for applying the sealing sheet to which the release liner is attached to the sealing layer while heating and pressing the semiconductor substrate,
An imaging process for acquiring a transmission image by blasting X-rays onto the semiconductor substrate to which the sealing sheet is attached;
Inspecting the presence or absence of voids from the transmission image, an inspection process for obtaining the position of the voids,
The sealing sheet sticking method characterized by having provided. In the sealing sheet sticking method of Claim 1,
Based on the void position obtained in the inspection process, a needle is pierced to the void of the sealing layer to form a discharge flow path, and then the discharge sheet is removed while removing the void by reheating and pressurizing the sealing sheet. Repair process to repair,
A main press-bonding process in which the sealing sheet from which voids have been removed in the repairing process is cured and finally press-bonded to the semiconductor substrate;
The sealing sheet sticking method characterized by having provided. In the sealing sheet sticking method according to claim 1 or 2,
The said restoration process removes a void from a sealing layer, decompressing in a decompression chamber. The sealing sheet sticking method characterized by the above-mentioned.

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