JP5095114B2 - Method for manufacturing solid-state imaging device - Google Patents

Description

  The present invention relates to a method for manufacturing a solid-state imaging device, and more particularly to a method for manufacturing a solid-state imaging device in which a sensor package in which an image sensor of an imaging chip is sealed with a cover member is sealed with a resin.

  Digital cameras and video cameras that use a solid-state imaging device such as a CCD or CMOS type have become widespread. In addition, a solid-state imaging device and a memory are incorporated in an electronic device such as a personal computer, a mobile phone, and an electronic notebook, and a photographing function is added. Since the solid-state imaging device has a large influence on the external size of an electronic device or the like in which the solid-state imaging device is incorporated, it is desired to reduce the size thereof.

  In order to reduce the size of the solid-state imaging device, a solid-state imaging device using a chip-size package (hereinafter abbreviated as CSP) that can be packaged with the same size as a bare chip has been invented. In this CSP type solid-state imaging device, for example, an imaging chip in which an image sensor such as a CCD and an input / output pad are formed on an upper surface and an upper surface of the imaging chip are bonded via a spacer to seal the image sensor. It is comprised from the cover glass (cover member) and the external electrode which connects a solid-state imaging device to the exterior (for example, refer patent document 1).

The CSP type solid-state imaging device is created by the following method, for example.
1. A large number of image sensors and input / output pads corresponding to these are formed on the upper surface of the silicon wafer.
2. A spacer surrounding the outer periphery of each image sensor is formed on the silicon wafer.
3. A glass substrate which is a base material of a cover glass is bonded to the upper surface of the silicon wafer via a spacer, and each image sensor is sealed.
4). External electrodes corresponding to the image sensors are formed on the silicon wafer.
5. The silicon wafer and the glass substrate are separated into pieces by dicing or the like.

  Since the CSP type solid-state imaging device has a very small outer size comparable to that of a bare chip, a large number of external electrodes are provided on the lower surface of the chip substrate. Therefore, in the conventional CSP type solid-state imaging device, wiring from the input / output pad provided on the upper surface of the imaging chip to the external electrode on the lower surface is also performed in the external electrode forming step. As this wiring, a through wiring formed through the imaging chip or a side wiring formed on the side surface of the imaging chip is used.

The external electrode forming step using the through wiring is formed by the following method, for example (see Non-Patent Document 1).
1. A through hole is formed in the silicon wafer from the lower surface to the input / output pad.
2. An insulating film is formed on the inner wall surface of the through hole.
3. A through wiring is formed by copper plating in the through hole.
4). A secondary wiring that is electrically connected to the through wiring is formed on the lower surface of the silicon wafer.
5. A solder ball is formed on the secondary wiring.

Moreover, the external electrode formation process using side wiring is formed by the following methods, for example (for example, refer patent document 2).
1. A reinforcing plate is bonded to the lower surface of the silicon wafer.
2. Secondary wiring is formed on the lower surface of the reinforcing plate.
3. A notch that extends from the lower surface of the reinforcing plate to the input / output pad is formed in a portion that becomes the side surface of the solid-state imaging device after dicing.
4). A conductive film connecting the input / output pad and the secondary wiring is formed in the notch.
5. A solder ball is formed on the secondary wiring.
The conductive film provided in the cutout is disposed on the side surface of the solid-state imaging device by dicing the silicon wafer, and serves as side wiring.
JP 2001-257334 A US 6,777,767 B2 “Press release Next-generation packaging technology with through electrodes on semiconductor chip completed at practical level”, [online], Technology Research Association, Advanced Electronic Technology Development Organization, [Search February 15, 2005], Internet <URL ; Http://www.aset.or.jp/press_release/si_20040218/si_20040218.html>

  The creation of the through wiring requires many operations such as etching, cleaning, film formation, and plating, and the number of man-hours is very large. Furthermore, since a large number of dedicated devices (for example, an etcher, a CVD device, a plating device, etc.) are required, there is a problem that the cost is high. In addition, in order to clear quality such as electrical characteristics and reliability, there is a problem that it takes time to determine the conditions such as the shape of the through hole, the insulating film thickness, the thickness of the conductive paste, and the evaluation.

  Side wiring is expensive because of the same reason as the through wiring. Further, since the wiring is routed from the side surface to the lower surface of the imaging chip, the pitch of the input / output pads is required to be 350 μm or more, and the size of the solid-state imaging device is increased. As the size of the solid-state imaging device increases, the number of impositions of the image sensor on the silicon wafer decreases, and the cost increases.

  In Patent Document 1, a CSP type solid-state imaging device (hereinafter referred to as a sensor package) having no external electrode is fixed on a wiring board, and a bonding wire is provided between an input / output pad and a conductor pad of the wiring board. A package configuration of a solid-state imaging device is disclosed in which the outer periphery of the sensor package is sealed with a sealing resin.

  According to the resin-encapsulated package, although the size of the solid-state imaging device after completion of the package is slightly increased, it is possible to manufacture at a low cost because the technology and equipment for the post-process of the conventional semiconductor device can be used. Problems with through wiring and side wiring can be solved. In addition, since the space surrounded by the imaging chip, spacer, and cover glass can be sealed with sealing resin, fogging of the cover glass caused by moisture entering the space and poor image sensor electrical operation. Etc. can also be prevented.

  However, Patent Document 1 does not describe a method of resin-sealing the outer periphery of the cover glass while protecting the upper surface of the cover glass. When the upper surface of the cover glass is clogged or soiled with a resin, the yield is deteriorated and the cost is increased. Therefore, establishment of an appropriate resin sealing method is desired.

  In addition, there is an increasing demand for a system-in-package (hereinafter abbreviated as SIP) in which a plurality of IC chips that have been individually mounted on a wiring board in the past are mounted in a single package and systemized. When creating a SIP using the sensor package, the glass cover must be exposed to the outside. Compared to a SIP that does not require a part of the chip to be exposed to the outside, such as a SIP such as a CPU or memory. It is necessary to devise the arrangement of the package.

  Resin-sealed packages are conventionally used for various semiconductor elements, but problems due to moisture absorption between the sealing resin and the wiring board are known. The problem is that when a semiconductor device packaged with resin is soldered with a reflow device or the like, the moisture sucked into the sealing resin is heated to cause a steam explosion, and the sealing resin or sealing Cracks occur at the interface between the resin for the sensor and the sensor package, and the sealing resin is peeled off from the sensor package or the wiring board.

  When the above-described problem occurs in the solid-state imaging device described in Patent Document 1, the bonding wire connected to the input / output pad and the conductor pad is disconnected due to cracking or peeling of the sealing resin, and the solid-state imaging device becomes inoperable. In addition, ionic impurities are eluted from the encapsulating resin by the incorporated moisture, and this may accelerate the electrochemical decomposition reaction of the input / output pad made of Al and corrode it. Furthermore, when the sealing resin is peeled off from the sensor package or wiring board, the spacer or cover glass moves together with the sealing resin and peels off from the imaging chip, resulting in fogging of the cover glass or poor image sensor electrical operation. Etc. occur.

  As described above, in the solid-state imaging device, various problems occur due to moisture absorption of the sealing resin. However, Patent Document 1 does not disclose any technique for solving the problem due to humidity. Establishment of appropriate moisture resistance method is desired.

  The present invention has been made to solve the above-described problems, and provides a method for manufacturing a solid-state imaging device that can perform resin sealing while appropriately protecting a cover glass and prevent adverse effects due to humidity.

  In order to solve the above-described problems, a method for manufacturing a solid-state imaging device according to the present invention includes a die bonding step of fixing a sensor package in which an image sensor is sealed with a cover member on an assembly wiring board, and an input / output pad of each sensor package. A wire bonding process for connecting internal electrodes provided on the assembly wiring board corresponding to each sensor package with a bonding wire, a protection process for covering the upper surface of each cover member with a mask, and sealing on the assembly wiring board It comprises a sealing step of sealing the outer periphery of each sensor package by vacuum screen printing of the resin, and an individualization step of cutting the assembly wiring board and the sealing resin for each sensor package.

  According to the above manufacturing method, the upper surface of the cover member is protected by the mask in the protection step, and the variation in the height dimension of the sensor package is absorbed by the mask, so that the sealing resin adheres to the upper surface of the cover member. Can be prevented. Thereby, deterioration of the yield due to the sealing resin fouling the cover member can be prevented, and portions other than the upper surface of the cover member can be appropriately sealed. In addition, since a large number of solid-state imaging devices can be manufactured together, the cost can be reduced.

  In addition, when the SIP is formed by fixing the sensor package and at least one cooperating chip cooperating with the sensor package on the same assembly wiring board, the sensor is arranged so that the upper surface of the cover member is not hidden by the cooperating chip. The package and the cooperating chip are fixed on the wiring board, and the upper surface of the cover member is protected with a mask so that the upper surface of the cover member is not contaminated with the sealing resin, and then vacuum screen printing is performed. Thereby, also in the solid-state imaging device using SIP, it is possible to prevent the yield from being deteriorated and to appropriately seal the portions other than the upper surface of the cover member. In addition, since a large number of solid-state imaging devices using SIP can be manufactured at a time, the cost can be reduced.

  The mask can be provided with an outer wall portion that surrounds the outer periphery of the assembly wiring board and restricts the printing range of the sealing resin, together with a mask portion that covers the upper surface of each cover member. Thereby, since the range of vacuum screen printing can be decided, useless use of sealing resin can be prevented.

  Further, as the mask, a protective sheet having a similar shape having a larger area than the light receiving surface of the image sensor and having an area smaller than the upper surface of the cover member is used, and the edge of the protective sheet is the light receiving surface of the image sensor. It is good to affix on the upper surface of a cover member so that it may fit between the edge of this, and the edge of the upper surface of a cover member.

  When the edge of the protective sheet protrudes outside the cover member, the edge of the protective sheet may bend and enter the sealing resin during vacuum screen printing of the sealing resin in the sealing step. When the protective sheet in such a state is peeled off from the cover member, a recess is formed in a portion where the protective sheet has entered the sealing resin, and sealing performance and appearance quality are deteriorated. In this invention, since the edge part of a protection sheet is made not to protrude from the upper surface of a cover member, the said problem does not generate | occur | produce. Further, since the area of the protective sheet is larger than the area of the light receiving surface of the image sensor, the performance of the image sensor is not affected. Moreover, when using a protection sheet, it is good to provide an outer wall part separately.

  Further, as vacuum screen printing, a step of screen-printing a sealing resin on the outer periphery of each sensor package at a first air pressure lower than atmospheric pressure, and a step in which the air pressure is higher than the first air pressure and lower than atmospheric pressure. And a step of screen-printing the sealing resin again on the outer periphery of each sensor package. According to this, the outer periphery of the sensor package can be appropriately sealed without causing bubbles or the like in the sealing resin. The first atmospheric pressure is preferably, for example, 100 Pas, and the second atmospheric pressure is preferably, for example, about 20000 to 90000 Pas.

  Further, potting may be used when the sensor package is sealed with a sealing resin. In addition, when using potting, it is preferable to perform the formation process of the retaining wall used as the flow stop of sealing resin on the outer periphery of an assembly wiring board before this process. The sealing of the sensor package using the potting sealing step and the retaining wall forming step can also be used for manufacturing a solid-state imaging device using SIP.

  You may form a retaining wall by raising a dam material over the perimeter of the outer periphery of aggregate wiring. As this dam material, it is preferable to use the same material as the sealing resin so as not to cause a crack with the sealing resin. Further, the thermal expansion coefficient is preferably 13 ppm / ° C. or less so that cracks and the like do not occur due to the difference in thermal expansion coefficient between the sensor package and the assembly wiring board. Furthermore, considering the workability at the time of forming the retaining wall, the viscosity of the dam material at the time of forming the retaining wall is preferably about 400 to 550 Pas. Furthermore, if the retaining wall formed of the dam material is cured together with the sealing resin in the mold curing process, it is possible to prevent an increase in the number of processes due to the provision of the retaining wall.

  Further, when the sensor package is fixed to the fixing portion of the assembly wiring board, a film-like die attach material may be used. When using a paste or liquid die attach material, the height of each cover member on the assembly wiring board will be uneven if the coating thickness is not strictly controlled, creating a gap between the mask and the cover glass. And is soiled by the sealing resin. However, the use of a film-like die attach material with uniform thickness eliminates variations in the height of each cover member on the assembly wiring board, so that the upper surface of each cover member can be more reliably protected. It is possible to prevent the yield from deteriorating due to contamination of the sealing resin to the cover member.

  Moreover, it is preferable that the glass transition temperature of the die attach material is lower than the heat curing temperature of the mold curing process for heat curing the sealing resin. As a result, since the die attach material reaches the glass transition temperature in a state where the temperature is still low immediately after the start of mold curing, the difference in thermal expansion coefficient between the imaging chip and the assembly wiring board is absorbed, and the sealing resin cracks. It can prevent peeling. The glass transition temperature of the die attach material is preferably about 50 to 80 ° C. and the thermal expansion coefficient is about 80 to 100 ppm / ° C., for example.

  Also, during mold curing, the glass transition temperature of this adhesive is the heat curing temperature in the mold curing process so that the adhesive used to attach the imaging chip and the cover member does not reach the glass transition temperature and the adhesive force is not reduced. The above is preferable. When the thermal expansion coefficient of the sealing resin is low and the stress on the adhesive due to thermal stress at high temperature is small, the glass transition temperature or lower may be used.

  As the collective wiring board, a substrate substrate that has been widely used in semiconductor devices in the past can be used. As the external electrode, a solder ball or a solder paste can be used. Since the substrate substrate and the external electrode have high reliability and low cost, they can contribute to improvement in yield and cost reduction of the solid-state imaging device.

  A lead frame can also be used as another collective wiring board. When a lead frame is used, the outer lead of the lead frame is plated in the external electrode forming step. Since this lead frame also has high reliability and low cost, it can contribute to improvement in yield and cost reduction of the solid-state imaging device. In addition, when using PPF (Pre Plated Frame) which is a plated lead frame, this plating step can be omitted.

  Moreover, a tape board | substrate can also be used as another assembly wiring board. In particular, when a super heat-resistant polyimide film is used as the tape substrate, the sealing resin plays a role in discharging moisture absorbed by the sealing resin, so that the influence of water vapor explosion in the sealing resin can be reduced.

Between the die bonding and the wire bonding step may be provided a washing step for cleaning the sensor package and the current focus wiring board. By this cleaning process, the adhesion between the sensor package and the sealing resin is improved, and the reliability of the solid-state imaging device can be improved. As a cleaning method, UV cleaning or plasma cleaning is suitable.

Furthermore, cracks and the sealing resin, sensor package and to prevent peeling from the wiring board, sealing resin with high adhesion resin having a tight adhesion with respect to the sensor package and the current focus circuit board It is preferable to use as. As this highly adhesive resin, for example, a bisphenol-based epoxy resin can be used. As the curing agent used for this resin, amine-based or polyamine-based ones are suitable.

  The viscosity of the sealing resin is preferably 100 Pas or less, for example, in order to improve workability and prevent the generation of voids. In addition, as a sealing resin, when using a resin that has a high viscosity at normal temperature and a viscosity that decreases by heating, it is preferable to heat and fill the resin for sealing.

  Moreover, in order to reduce the thermal stress between the sealing resin and the sensor package and the wiring board, the thermal expansion coefficient of the sealing resin is preferably 12 ppm / ° C. or less. For the same reason, it is preferable that the sealing resin has a flexural modulus of 28 GPa or less and a molding shrinkage of 0.12% or less.

Furthermore, the moisture sealing resin is often absorbed, so causing cracks and peeling, the water absorption of the sealing resin is desirably a hereinafter 0.3 wt%.

  In order to further reduce the water absorption rate of the sealing resin, a sealing resin having a filler filling rate of 80% or more may be used. Further, in order to satisfy the filling rate of the filler, the filler filled in the sealing resin is composed of the first filler and the second filler having a smaller size than the first filler to increase the filling efficiency. Is preferred.

  In order to improve temperature cycle suitability, the glass transition temperature of the sealing resin is preferably 150 ° C. or higher.

  Further, in order to keep the strength of the solid-state imaging device appropriate and prevent deformation, the hardness at the time of sealing tree is preferably 90 or more on Shore D.

  In order to prevent the input / output pad from corroding due to the elution of impurities from the sealing resin, it is preferable to use a sealing resin having halogen and alkali metal contents of 10 ppm or less.

  According to the present invention, while taking advantage of the small size of the CSP type solid-state imaging device, it is possible to solve the problems such as high cost, low reliability, and increased chip size that the through wiring and the side wiring have. Further, since the upper surface of the cover member of the sensor package is not soiled during resin sealing, the cost of the solid-state imaging device does not increase due to the deterioration of the yield. Furthermore, a system-in-package using a CSP type solid-state imaging device can also produce a highly reliable product at low cost.

  Furthermore, although various problems such as cracks, peeling, and inoperability occur due to moisture absorption of the sealing resin, it can be solved by using various improved techniques of the present invention selectively or in combination as appropriate. .

  1 and 2 are an external perspective view and a cross-sectional view showing the configuration of the solid-state imaging device 2 using the first embodiment of the present invention. The solid-state imaging device 2 includes a rectangular wiring board 3, a sensor package 4 fixed on the wiring board 3, a plurality of bonding wires 5 connecting the wiring board 3 and the sensor package 4, and a sensor package. 4 is composed of a sealing resin 7 for sealing the outer periphery of the cover glass 6 and external conductor pads 8 formed on the lower surface of the wiring board 3. The solid-state imaging device 2 has a package form called a so-called Fine pitch Land Grid Array (FLGA). Since this FLGA package is a conventional packaging method, the solid-state imaging device 2 can be manufactured at low cost and with high reliability.

  The wiring board 3 is a substrate board (printed board) using glass epoxy or the like as a base material 11, and a plurality of internal parts used for connection to the sensor package 4 by bonding wires 5 are formed on the upper and lower surfaces of the base material 11. An internal conductor pad 12 that is an electrode and an external conductor pad 8 that is an external electrode are formed. The internal conductor pads 12 and the external conductor pads 8 are formed using, for example, Cu, and are electrically connected by a conductive film 14 formed in a through hole 13 that penetrates the base material 11. The upper and lower surfaces of the wiring board 3 are covered with solder resists 15 and 16 except for the internal conductor pads 12 and the external conductor pads 8.

  The sensor package 4 includes a rectangular imaging chip 19, a plurality of input / outputs used for connection between the image sensor 20 such as a CCD or CMOS provided on the upper surface of the imaging chip 19, and the wiring board 3 by bonding wires 5. The pad 21, a transparent cover glass 6 that seals the upper side of the image sensor 20, and a spacer 22 that is sandwiched between the imaging chip 19 and the cover glass 6.

  The imaging chip 19 is formed by dividing a silicon wafer on which a large number of image sensors 20 and input / output pads 21 are formed into a rectangular shape. The image sensor 20 has a large number of light receiving elements arranged in a matrix, and an RGB color filter and a microlens array 20a composed of a large number of microlenses are stacked on each light receiving element. Yes. A plurality of input / output pads 21 are formed side by side on two sides sandwiching the image sensor 20. These input / output pads 21 are formed, for example, by printing using Au, Al or the like, and are connected to the image sensor 20 by wiring formed by the same material and method.

  The spacer 22 is formed in a square shape having an opening 22a in the center using, for example, an inorganic material such as silicon. The spacer 22 is joined to the upper surface of the imaging chip 19 so as to surround the outer periphery of the image sensor 20, and forms a gap between the image sensor 20 and the cover glass 6. This prevents the microlens array 20a from interfering with the cover glass 6.

  The cover glass 6 is made of low α-ray glass joined to the upper surface of the spacer 22 so as to close the opening 22a. The low α-ray glass is a glass that emits less α-ray and prevents the light receiving element of the image sensor 20 from being broken by the α-ray. Note that an infrared cut filter or an optical low-pass filter may be bonded to the upper surface of the cover glass 6.

  The sensor package 4 is die-bonded on the wiring board 3. Au or Al is used for the bonding wire 5 that connects the input / output pad 21 and the internal conductor pad 12. For the sealing resin 7 that seals the outer periphery of the cover glass 6, for example, an epoxy resin that is a thermosetting resin conventionally used for sealing an IC is used. The sealing resin 7 prevents oxidation and corrosion of the input / output pad 21, the internal conductor pad 12, and the bonding wire 5 due to moisture and oxygen in the air, and improves the mechanical strength of the solid-state imaging device 2.

  Next, the manufacturing process of the solid-state imaging device 2 will be described with reference to the flowcharts of FIGS. In addition, the material and apparatus used in each process are described on both sides of the flowchart. The first manufacturing process of the solid-state imaging device 2 is the manufacturing of the sensor package 4.

  In the manufacturing process of the sensor package, first, a glass substrate that is a base material of the cover glass 6 and a spacer wafer that is a base material of the spacer 22 are joined. As shown in FIG. 5A, an adhesive is applied to the lower surface of the glass substrate 28 using a coater such as a bar coater, a blade coater, or a spin coater. Next, the spacer wafer 30 is bonded to the lower surface of the glass substrate 28 by a bonding apparatus capable of holding and moving the glass substrate 28 and the spacer wafer 30 in parallel. A normal temperature curable adhesive is used as the adhesive 29, but a UV curable adhesive, a visible light curable adhesive, a thermosetting adhesive, or the like may be used. Further, the bonding may be performed in a vacuum environment so that air does not enter between the glass substrate 28 and the spacer wafer 30 during the bonding.

  In the next step, as shown in FIG. 5B, a thinning step for reducing the thickness of the glass substrate 28 and the spacer wafer 30 is performed. The glass substrate 28 and the spacer wafer 30 are made thicker in order to improve the handling suitability at the time of bonding and to reduce the cost by using a standard wafer. Thus, the solid-state imaging device 2 can be reduced in size and the etching time can be shortened. In this thinning step, for example, a grinding / polishing apparatus is used.

  In the next step, the spacer 22 is processed. First, as shown in FIG. 5C, a resist 33 is applied to the lower surface of the spacer wafer 30. Next, as shown in FIG. 4D, the resist 33 is exposed using a predetermined mask and developed as shown in FIG. 4E, whereby a resist mask 34 representing the form of the spacer 22 is obtained. Complete. For the creation of the resist mask 34, a coater developer, an exposure device, a developing device, or the like is used.

  The spacer wafer 30 on which the resist mask 34 is formed is etched by a dry etcher, and a portion not covered with the resist mask 34 is removed as shown in FIG. As a result, a large number of spacers 22 are formed on the lower surface of the glass substrate 28. The resist mask 34 and the adhesive 29 after etching are removed by a cleaning device as shown in FIG.

  In the next step, as shown in FIG. 7, a glass substrate 28 on which a large number of spacers 22 are formed and a silicon wafer 37 on which a large number of image sensors 20 and input / output pads 21 are formed are bonded. . In the first step, as shown in FIG. 6A, an adhesive 40 is applied on each spacer 22. A normal temperature curable adhesive is used as the adhesive 40, but a UV curable adhesive, a visible light curable adhesive, a thermosetting adhesive, or the like may be used.

  Next, as shown in FIG. 6B, the spacers 22 on the glass substrate 28 and the silicon wafer 37 are bonded. For this joining, since it is necessary to strictly adjust the position of each image sensor 20 and the spacer 22, a joining apparatus having an alignment function for adjusting the parallelism between them and the position in the horizontal direction is used. Since each image sensor 20 on the silicon wafer 37 is sealed by the spacer 22 and the glass substrate 28, the image sensor 20 is not contaminated by dust generated in the subsequent processes.

  In the next step, the glass substrate 28 and the silicon wafer 37 are diced for each image sensor 20 and separated into individual pieces. First, as shown in FIG. 6C, the silicon wafer 37 is fixed on a dicing tape 43 provided with an adhesive layer 43a on the upper surface, and a protective tape similarly provided with an adhesive layer 44a on the glass substrate 28. 44 is attached.

  Next, as shown in FIG. 6D, the glass substrate 28 is diced along the end face of each spacer 22 using a slicer. Further, as shown in FIG. 5E, the silicon wafer 37 is diced for each image sensor 20 using a dicer, and a large number of sensor packages 4 are collectively formed. The protective tape 44 remains attached to protect the cover glass 6 at the time of shipment. Further, when a protective tape is not used during dicing, the protective tape is individually attached to each cover glass 6 after dicing.

  In the next inspection process, for example, functional inspection of each sensor package 4 is performed using a probe inspection apparatus. The sensor package 4 that has passed this function inspection is peeled off from the dicing tape 43 in the next storage step, stored in a tray, or attached to a carrier tape and ready for shipment. A large number of sensor packages 4 may be shipped in a state of being fixed on the dicing tape 43.

  As shown in FIG. 3, the completed sensor package is die-bonded on the assembly wiring board in the next die-bonding step. As shown in FIGS. 8A and 9, the assembly wiring board 47 is formed in a rectangular shape by, for example, a glass epoxy base material, and the upper surface serves as a fixing portion to which the sensor package 4 is die-bonded in a matrix shape. , 20 die bond regions 48 are provided. In each die bond region 48, the inner conductor pad 12 and the outer conductor pad 8 are formed in advance. The number of die bond regions 48 is not limited to 20 and may be more or less than this.

  A die bonder used in the die bonding process attaches a die attach film 51 to each die bond region 48 of the assembly wiring board 47. Next, the die bonder places the sensor package 4 on each die attach film 51 as shown in FIG. The collective wiring board 47 on which the sensor package 4 is placed is heated using a heating device such as an oven, and the die attach film 51 is cured. Thereby, each sensor package 4 is fixed onto the collective wiring board 47.

  In the case of using a paste-like or liquid-like die attach material, the height of each cover glass 6 on the assembly wiring board 47 becomes non-uniform unless the coating thickness is strictly controlled. In the printing process, the upper surface of each cover glass 6 is not properly protected and is soiled by the sealing resin 7. However, the use of the die attach film 51 having thickness uniformity as the die attach material eliminates the variation in the height dimension of each cover glass 6 on the collective wiring board 47, so that the upper surface of the cover glass 6 in the printing process. Can be more reliably protected, and the yield can be prevented from deteriorating due to the contamination of the sealing resin 7 to the cover glass. The die attach film 51 may be bonded to each sensor package 4 in advance. Moreover, when the problem by the dispersion | variation in the height dimension of the cover glass 6 does not arise, a paste-like die attach material can also be used.

In the next cleaning step, for example, each sensor package 4 and the collective wiring board 47 are cleaned using an O ₂ asher. This cleaning is performed in order to improve wire bondability in the wire bond process described later and resin adhesion in the printing process.

  As shown in FIG. 8C, in the next wire bonding step, a wire bonder is used to bond between the input / output pads 21 of each sensor package 4 and the inner conductor pads 12 of each die bond region 48 by the bonding wires 5. Connected. This wire bonding step is preferably performed in a low loop so that the bonding wire 5 does not protrude upward from the upper surface of the cover glass 6.

  In the next step, as shown in FIG. 8D, the upper surface of the assembly wiring board 47 and the outer periphery of each sensor package 4 are sealed with the sealing resin 7. The resin sealing is provided with a protection process for protecting the upper surface of each cover glass 6 together with a printing process for actually sealing.

  As shown in FIG. 10, a vacuum screen printing device 54 is used in the printing process. The vacuum screen printing apparatus 54 includes a chamber 55 having airtightness and pressure resistance, a horizontal movement stage unit 56 installed in the chamber 55, a resin supply unit 57, a printing unit 58, and the chamber 55 with reduced pressure. And a vacuum pump 59 for pressurization.

  The horizontal movement stage unit 56 includes a stage 61 on which the collective wiring board 47 is placed, and a stage movement mechanism 62 that horizontally moves the stage 61 in the horizontal direction in the drawing. The resin supply unit 57 includes a supply tank 63 that stores and supplies the paste-like sealing resin 7 and a nozzle 64 that discharges the paste-like sealing resin 7 in the vicinity of the assembly wiring board 47. The printing unit 58 includes a squeegee 65 that is in contact with the upper surface of the collective wiring board 47 and a squeegee moving mechanism 66 that is used for surface alignment with the collective wiring board 47 and gap adjustment by moving the squeegee 65 in the vertical direction.

  FIG. 11 is a plan view of the stage 61, on which three collective wiring boards 47 are set. In the protection process, the outer wall portion 68 a that regulates the printing range of the sealing resin 7 and the upper surface of the cover glass 6 of each sensor package 4 are protected on the three collective wiring boards 47 set on the stage 61. The mask 68 provided with the mask part 68b to cover is covered. Since the height dimension of each cover glass 6 on the collective wiring board 47 does not vary due to the thickness uniformity of the die attach film 51, the upper surface of each cover glass 6 is appropriately covered with each mask portion 68b. Therefore, the sealing resin 7 does not adhere to the upper surface of the cover glass 6.

As shown in FIG. 12, each mask part 68b is connected with the adjacent mask part 68b and the outer wall part 68a by the connection part 68c formed very thinly. Note that the sealing resin 7 is not printed on the portion where the connecting portion 68c is present, but the connecting portion 68c is formed very thin, so that the sealing performance is not affected.

  Printing of the sealing resin 7 is performed according to the procedure shown in the flowchart of FIG. First, the three collective wiring boards 47 are set on the stage 61 and fixed by suction so as not to move. The squeegee 65 is moved in the vertical direction by the squeegee moving mechanism 66, and surface alignment with the upper surface of the collective wiring board 47 and clearance adjustment are performed. The resin supply unit 57 discharges an appropriate amount of the sealing resin 7 from the nozzle 64 and supplies it onto the assembly wiring board 47.

  The vacuum pump 59 discharges the air in the chamber 55 through the pipe 59a and reduces the pressure to the first atmospheric pressure. The stage moving mechanism 62 moves the stage 61 toward the left A direction in the drawing. As a result, as shown in FIG. 14A, the sealing resin 7 is filled around the sensor package 4 by the squeegee 65.

  When the stage 61 moves to a position indicated by a two-dot chain line in FIG. 10, the first vacuum screen printing is completed. The vacuum pump 59 slightly opens the air supply valve and pressurizes the atmospheric pressure in the chamber 55 to the second atmospheric pressure. This second atmospheric pressure is an atmospheric pressure lower than the atmospheric pressure. As shown in FIG. 14B, when gaps or bubbles are generated in the sealing resin 7 filled by the first vacuum screen printing, the first and second pressures Due to the pressure difference, the sealing resin 7 is sucked into the gaps or bubbles.

  Due to the pressurization to the second atmospheric pressure, the surface of the sealing resin 7 is recessed, so that the second vacuum screen printing for correcting this is performed. Similar to the first vacuum screen printing, the resin supply unit 57 discharges an appropriate amount of the sealing resin 7 from the nozzle 64 and supplies it onto the assembly wiring board 47. The stage moving mechanism 62 moves the stage 61 from the A direction toward the B direction. As a result, as shown in FIG. 14C, the sealing resin 7 is filled around the sensor package 4 by the squeegee 65.

  After the second vacuum screen printing, the vacuum pump 59 is stopped, the air supply valve is opened, and the inside of the chamber 55 is raised to atmospheric pressure. Further, the squeegee moving mechanism 66 raises the squeegee 65 and retracts the tip from the assembly wiring board 47. Accordingly, as shown in FIG. 14D, the outer periphery of each sensor package 4 is sealed with the sealing resin 7, and the surface of the sealing resin 7 is also smoothed.

  After the vacuum screen printing is completed, the assembled wiring board 47 is taken out from the vacuum screen printing device 54, and the mask 68 is removed. The sealing resin 7 immediately after molding is not sufficiently polymerized and the characteristics are not stable. Therefore, in the next post mold cure (PMC) step, the assembly wiring board 47 is accommodated in an oven and heated at a high temperature to cure the sealing resin 7.

  As the sealing resin, an epoxy resin that is a thermosetting resin is suitable. For example, a resin having a viscosity of 450 Pas at room temperature, a Young's modulus of 25000 Mpas, and a coefficient of thermal expansion of about 12 ppm / ° C is a vacuum. Suitable for screen printing construction. In addition, as the first atmospheric pressure, for example, 100 Pas or less and the second atmospheric pressure are preferably about 20000 to 90000 Pas.

  After the printing process, in the marking process, a manufacturer name, a product name, a manufacturing number, a lot number, and the like are printed on the sealing resin 7 with a laser marker.

  In the next process, a singulation process is performed, which is an individualization process in which the assembly wiring board 47 and the sealing resin 7 are separated into individual sensor packages 4. First, as shown in FIG. 8E, the upper surface of the assembly wiring board 47 (the surface on which the cover glass 6 is exposed) is stuck on the dicing tape 71. Next, as shown in FIG. 8F, the dicing is used to dice the sealing resin 7 and the collective wiring board 47 for each sensor package 4 from the back side. Thereby, a large number of solid-state imaging devices 2 are collectively formed.

  In the next storage step, each solid-state imaging device 2 is peeled off from the dicing tape 71 by the storage device and stored in a tray, or attached to a carrier tape and ready for shipment. A large number of solid-state imaging devices 2 may be shipped in a state of being fixed on the dicing tape 71.

  In the above embodiment, the cover glass 6 of each sensor package 4 is protected by the mask portion 68b of the mask 68, but a protective sheet may be attached to the upper surface of each cover glass 6. In this case, for example, as shown in FIG. 15, a protective sheet 75 having an area larger than the light receiving surface of the image sensor 20 and an area smaller than the upper surface of the cover glass 6 is used. The protective sheet 75 may be attached to the upper surface of the cover glass 6 such that the edge of the protective sheet 75 is located between the edge of the light receiving surface of the image sensor 20 and the upper edge of the cover glass 6. The protective sheet 75 may be applied individually to each cover glass 6 or may be applied together using a jig or the like.

  Note that the size of the protective sheet 75 is made smaller than the upper surface of the cover glass 6 when the edge of the protective sheet 75 protrudes outside the cover glass 6 due to the filling of the sealing resin 7. This is because the end portion is bent and enters the sealing resin 7. When the protective sheet 75 in such a state is peeled off from the cover glass 6, a recess is formed in a portion where the protective sheet 75 has entered the sealing resin 7, and sealing performance and appearance quality are deteriorated. In the present embodiment, since the end portion of the protective sheet 75 does not protrude from the upper surface of the cover glass 6, the above problem does not occur. Further, since the area of the protective sheet 75 is larger than the area of the light receiving surface of the image sensor 20, the performance of the image sensor 20 is not affected.

  When the upper surface of the cover glass 6 is protected using the protective sheet 75, an outer wall portion that surrounds the outer periphery of the assembly wiring board 47 and restricts the filling range of the sealing resin 7 is separately required. As the outer wall portion, only the outer wall portion 68 a of the mask 68 described above may be used, or a retaining wall may be formed of resin on the outer periphery of the collective wiring board 47.

  Moreover, although the said embodiment demonstrated the manufacturing method of the solid-state imaging device using a FLGA package, this invention is a solid-state imaging device using the Fine pitch Ball Glid Array (FBGA) package which uses a solder ball as an external electrode. It can also be applied to. As shown in FIGS. 16 and 17, in the solid-state imaging device 78 using the second embodiment of the present invention, a solder ball 82 is provided on an external conductor pad 81 of a wiring board 80 to which a sensor package 79 is fixed. ing. Since this FBGA package is also a conventionally used packaging method, the solid-state imaging device 78 with high reliability can be manufactured at low cost.

  When manufacturing the FBGA package solid-state imaging device 78, as shown in the flowchart of FIG. 18, a step of forming the solder ball 82 is provided between the marking step and the singulation step. As a method for forming the solder ball 82, for example, a ball mount method can be used. In this ball mounting method, in the ball mounting process, flux is applied and preliminary solder is applied to the external conductor pads 81 of the assembly wiring board, and the solder balls 82 are mounted on the external conductor pads 81 using a mounter. . In the next reflow process, the preliminary solder is heated and melted by the reflow apparatus, and the solder balls 82 are fixed onto the external conductor pads 81. Finally, the flux is removed by a cleaning device.

  In each of the above embodiments, a printed circuit board is used as the assembly wiring board, but a tape substrate or a lead frame may be used. As is well known, the lead frame is a metal frame including a die pad to which a chip is fixed, an inner lead to be wire-bonded to an input / output pad of the chip, an outer lead to be an external electrode, and the like. A solid state imaging device can be obtained by die-bonding a sensor package to each of the die pads, performing wire bonding, and separating the resin package after resin sealing.

  19 and 20 are an external perspective view and a cross-sectional view of a solid-state imaging device 85 using the third embodiment of the present invention, and are called so-called quad flat non-leaded (QFN) formed using a lead frame. It has a package form. The solid-state imaging device 85 includes a die pad 87 to which the sensor package 86 is fixed, an inner lead 90 that is an internal electrode connected to the input / output pad 89 of the sensor package 86 by a bonding wire 88, and a lower surface of the sealing resin 91. The outer lead 92 is exposed to the outside and becomes an external electrode. Since this QFN package is also a conventional packaging method, a solid-state imaging device with high reliability can be manufactured at low cost. The die pad 87 is sealed to the lower surface with the sealing resin 91. However, in order to improve the heat dissipation of the sensor package 86, the lower surface of the die pad 87 may be exposed from the sealing resin.

  When manufacturing the solid-state imaging device 85 of this QFN package, as shown in the flowchart of FIG. 21, a burr removing process for exposing the outer lead 92 from the sealing resin 91 between the printing process and the marking process; And a plating step of plating the exposed outer lead 92. The reason why the burr removing process is performed before the marking process is to prevent the marking from being damaged when the abrasive grains are sprayed by the deflasher to remove the burr. In addition, when using PD-PPF (Palladium Pre Plated Frame) by which palladium plating was performed beforehand as a lead frame, the said plating process can be skipped.

  In each of the above embodiments, a single package solid-state imaging device using a sensor package has been described as an example. However, as shown in an external perspective view of FIG. 22, the sensor package 95 and the sensor package 95 cooperate with each other. A plurality of cooperating chips are fixed on the same wiring board 96 and sealed with a sealing resin 97 to form a system-in-package (SIP) solid-state imaging device 98 (fourth embodiment). You can also. According to the solid-state imaging device 98 using SIP, a camera unit can be configured only by attaching a photographing optical system on the cover glass 99, and the suitability for incorporation into various electronic devices can be improved. .

  As the cooperation chip, for example, an analog front end (AFE) chip 102 that digitizes an analog imaging signal input from the sensor package 95, a digital signal processor (DSP) chip 103 that processes digital image data, and the like. A power supply chip 104 or the like can be used.

  Moreover, each chip may be fixedly arranged on the wiring board 96 like the solid-state imaging device 98, or on the wiring board 111 like the solid-state imaging device 110 (fifth embodiment) shown in FIG. The power supply chip 112, the spacer 113, the DSP chip 114, the AFE chip 115, and the sensor package 116 may be stacked in this order to form a stacked system-in-package. In any case, sealing is performed so that the upper surface of the cover glass 117 of the sensor package 116 is exposed from the sealing resin 118.

  When manufacturing the solid-state imaging devices 98 and 110 using the SIP, work is performed on other cooperative chips together with the sensor packages 95 and 116 in the die bonding process and the wire bonding process. In the printing process, the surfaces other than the upper surfaces of the cover glasses 99 and 117 of the sensor packages 95 and 116 are sealed with sealing resins 97 and 118, and in the singulation process, a chip constituting the system has one wiring board 96 and 111. Divide into pieces so that they are placed on top.

  In the above embodiment, the sealing resin is filled by vacuum screen printing. However, since screen printing requires a dedicated mask, there is a problem that the cost is increased in a small production lot. Therefore, potting may be used instead of screen printing. The manufacturing of the solid-state imaging device using the potting is performed in substantially the same procedure as the manufacturing of the solid-state imaging device using the screen printing shown in FIG. 3, but instead of the printing process, as shown in FIG. A potting process is performed. In addition, detailed description is abbreviate | omitted about the same thing as the structure demonstrated in the said embodiment.

  As shown in FIG. 25A, first, the assembly wiring board 131 to which the plurality of sensor packages 130 are fixed and the wire bonding is completed is fixed on the work table of the potting apparatus. Next, as shown in FIG. 5B, the dam material syringe 134 in which the dam material 133 is housed is disposed on the outer peripheral edge of the collective wiring board 131, and the collective wiring is discharged while discharging the dam material 133 from the syringe 134. The dam material 133 is raised along the outer peripheral edge of the plate 131 to form a retaining wall 135 on the entire circumference. The retaining wall 135 regulates the filling range of the sealing resin. When the retaining wall 135 is formed, it is preferable to use a resin that has a high viscosity and that can be potted, for example, a resin having a viscosity of about 500 Pas so that the dam material 133 does not flow and the shape of the retaining wall 135 does not collapse.

  As shown in FIG. 25C, a sealing syringe 139 containing a liquid sealing resin 138 is disposed on the assembly wiring board 131, and each sensor package 130 is discharged while discharging the sealing resin 138. Move between. Thereby, the periphery of each sensor package 130 is sealed with the sealing resin 138 except for the upper surface of the cover glass 140.

  Thereafter, like the screen printing, the sealing resin 138 and the retaining wall 135 are heated and cured by a post mold curing process. Note that the sealing resin 138 and the retaining wall 135 are heat-cured together because only the retaining wall 135 is cured first, thereby causing the assembly wiring board 131 to be warped or the number of steps being increased. This is to avoid it.

  Then, as shown in FIG. 25D, a dicing tape 143 is attached to the lower surface of the collective wiring board 131, and the sealing resin 138 and the collective wiring board 131 are diced for each sensor package 130. Thereby, the solid-state imaging device 142 shown in FIG. 26 is formed. When filling the resin by potting, the upper surface of the sealing resin 138 may not be smooth, but the function of the solid-state imaging device 142 is not affected.

  Although the same material as the sealing resin is used as the material of the dam material, any material that is compatible with the sealing resin such as a thermal expansion coefficient can be used as the dam material. Further, when the thermal expansion coefficient of the dam material can be matched with that of the assembly wiring board and there is no problem even if the number of steps is increased, the retaining wall may be cured before supplying the sealing resin. The resin sealing by potting described above can also be used for manufacturing the above-described second to fifth solid-state imaging devices.

  A semiconductor device such as a solid-state imaging device needs to have high reliability so that a device in which the semiconductor device is incorporated can exhibit a predetermined function and performance for a desired period of time for an end user. Therefore, a standardized reliability test is performed on the semiconductor device. As a standard for semiconductor devices, for example, the JEDEC standard (Joint Electron Device Engineering Council (American Electronic Components Standardization Industry Association)) is known. The JEDEC standard also defines a reliability test for semiconductor devices. .

  The reliability test of the JEDEC standard includes a “pre-treatment” that applies stress to a semiconductor device before it is incorporated into various devices, and stress that is applied over a long period of time in actual use of the semiconductor device. It consists of a “main test” given at an accelerated rate. Further, “pre-processing” is defined as levels 1 to 3 according to the magnitude of the stress. The implementation conditions for the “pretreatment” and “main test” of the reliability test are described below.

JEDEC standards, reliability test conditions Pretreatment conditions (1) High temperature and high humidity storage conditions Level 1: Temperature 85 ° C, Humidity 85%, 168 hours Level 2: Temperature 85 ° C, Humidity 60%, 168 hours Level 3: Temperature 30 ° C, Humidity 60% 192 hours (2) Reflow conditions Preheating: temperature 160 ° C, 60 seconds Main heating: temperature 260 ° C, 20 seconds Main test (1) High temperature and high humidity storage test: temperature 85 ° C, humidity 85%, 1000 hours (2) Temperature cycle test: 85 ° C -40 ° C, 1000 cycles

  As a result of manufacturing the solid-state imaging device 2 of the first embodiment of the present invention and performing the reliability test of the JEDEC standard, various problems occurred and the reliability test could not be passed. The problem is that cracks occur in the sealing resin 7 or the interface between the sealing resin 7 and the sensor package 4 due to the steam explosion of moisture taken into the sealing resin 7. It is peeled off from the sensor package 4 and the wiring board 3, and the bonding wire 5 is detached from the internal conductor pad 12 and the input / output pad 21, resulting in malfunction.

  In addition, ionic impurities are eluted from the encapsulating resin 7 due to the incorporated moisture, and this causes a problem of accelerating the electrochemical decomposition reaction of the input / output pad 21 made of Al and causing corrosion.

  Furthermore, when the sealing resin 7 is peeled off, there is a problem that the spacer 22 and the cover glass 6 move together with the sealing resin and are peeled off from the imaging chip 19. According to this, the space surrounded by the imaging chip 19, the spacer 22, and the cover glass 22 is not properly sealed, and the cover glass 6 is clouded by moisture that has entered the space, and the electric operation of the image sensor 20 is performed. Defects occur.

  In the present invention, in order to obtain a solid-state imaging device capable of passing the reliability test, a structure change, various condition changes, and a sealing resin change described below were performed. Detailed descriptions of the same configurations as those described in the above embodiments are omitted.

  The present applicant considers that one of the causes for the sealing resin to peel off from the sensor package is the weakness of the fixing force of the sealing resin to the sensor package, and a novel structure capable of improving this fixing force. Invented.

  In the solid-state imaging device 150 shown in FIG. 27, a chamfered portion 153 is provided on the outer peripheral edge of the cover glass 152 of the sensor package 151. The chamfered portion 153 increases the contact area between the sealing resin 154 and the sensor package 151 and improves the fixing force of the sealing resin 154. Therefore, the anchor that prevents the sealing resin 154 from being peeled off from the sensor package 151 is obtained. An effect can be obtained. Further, even if the pressure in the space surrounded by the imaging chip 155, the spacer 156, and the cover glass 152 is increased by heat, the opposing reaction force acts on the cover glass 152, so that the sealing performance in this space is improved. be able to.

  In order to achieve the same purpose, in the solid-state imaging device 160 shown in FIG. 28, a stepped portion 163 is formed on the outer peripheral edge of the cover glass 162 of the sensor package 161 to increase the contact area with the sealing resin 164. ing. If the chamfered portion 153 and the stepped portion 163 are formed in a size that can be accommodated within the width dimension of the spacer, there is no adverse effect on the image sensor.

  The chamfered portion 153 and the stepped portion 163 can be formed using a slicer or a dicer when the glass substrate 28 and the silicon wafer 37 are diced as shown in FIGS. Therefore, there is no significant increase in the number of processes, and it can be adopted at a low cost.

  In the above embodiment, the anchor effect is obtained only by the outer peripheral edge of the cover glass. However, like the solid-state imaging device 170 shown in FIG. 29, the cover glass 172, the spacer 173, and the imaging chip 174 of the sensor package 171. The rough surfaces 175 and 176 may be formed on the entire circumference of the side surfaces of these, and the anchor effect for the sealing resin 177 may be obtained by these rough surfaces 175 and 176. The rough surfaces 175 and 176 can be easily formed by etching after dicing the glass substrate 28 and the silicon wafer 37, as shown in FIG. 6 (E).

  Further, as another method for making it difficult to peel off the sealing resin, it is conceivable to form a highly adhesive film on the outer peripheral surface of the sensor package to enhance the adhesiveness with the sealing resin. For example, a polyimide film 183 having a feature of low defect density is formed on the upper surface of the imaging chip 182 of the sensor package 181 as in the solid-state imaging device 180 shown in FIG. According to this, since the adhesiveness between the sealing resin 184 and the imaging chip 182 is improved, the fixing force of the sealing resin 184 is improved and it is difficult to peel off. In addition, since the adhesion between the imaging chip 182 and the spacer 185 is also improved, the adhesive force between the imaging chip 182 and the spacer 185 is improved, and it is difficult to peel off.

  The polyimide film 183 can be formed, for example, in the process of forming the image sensor 187 and the input / output pad 188 on the silicon wafer. The polyimide film 183 is also used as a passivation film during plasma etching. Therefore, when employed together with the aforementioned rough surface 175, the upper surface of the imaging chip 182 can be protected when the rough surface is formed on the side surfaces of the cover glass 186, the spacer 185, and the imaging chip 182 by plasma etching.

  Further, a moisture permeation preventive film can be used as a method for improving the sealing performance of the space in which the image sensor is accommodated. For example, if a nitride film 195 is deposited on the outer peripheral surface and upper surface of the cover glass 192 of the sensor package 191, the outer peripheral surface of the spacer 193, and the imaging chip 194 as in the solid-state imaging device 190 shown in FIG. Since the moisture permeation preventive property in the enclosed space is increased, the sealing property can be enhanced, and the peeling with the sealing resin 197 can be prevented. As shown in FIG. 8C, the nitride film 195 is deposited after the sensor package 4 is die-bonded to the assembly wiring board 47 and the input / output pads 21 and the internal conductor pads 12 of the assembly wiring board are wire-bonded. Good. Note that a nitride film has already been formed on the upper surface of the imaging chip 194 in the process of forming the silicon wafer 37, but vapor deposition may be further performed thereon.

  By preventing moisture permeation from the gap formed between the sealing resin, the sensor package and the wiring board, the moisture permeation preventing property by the nitride film and the adhesion property by the polyimide film can be prevented. Therefore, it is also effective in preventing cracking and peeling of the sealing resin due to steam explosion.

  Also, as one of the causes of the spacer peeling off from the imaging chip due to the peeling of the sealing resin, the air in the space sealed by the imaging chip, the spacer, and the cover glass is thermally expanded, and a load is applied to the bonded portion. Is considered to be related. In order to eliminate this cause, the space in which the image sensor is sealed may be evacuated. 32, an inert gas 205 such as N 2 gas may be filled into a space surrounded by the cover glass 202, the spacer 203, and the imaging chip 204 of the sensor package 201 as in the solid-state imaging device 200 shown in FIG. In order to evacuate the space or fill the inert gas 205, a chamber filled with a vacuum or an inert gas when the silicon wafer 37 and the glass substrate 28 are joined as shown in FIG. 6B. It is sufficient to perform the bonding within.

In each of the above embodiments, a new structure or the like is added to the sensor package to make it difficult to peel off the sealing resin. However, the adhesion of the nitride film provided in advance on the upper surface of the imaging chip is improved, and sealing is performed. The peeling of the stopping resin may be prevented. For example, UV cleaning or plasma cleaning is used to improve the adhesion. In the UV cleaning, the organic impurities attached to the nitride film can be removed and the wettability can be improved to improve the adhesion of the sealing resin. Further, in the plasma cleaning, the wire bondability with respect to the input / output pad can be improved, and the bonding force between the input / output pad and the bonding wire can be increased. As shown in FIG. 33, these UV cleaning or plasma cleaning may be performed in place of the O ₂ asher performed in the cleaning process of the first embodiment.

  In addition, the penetration of moisture into the sealing resin may be permeated through the wiring board in addition to directly penetrating from the surface of the sealing resin. Since the surface area of the wiring board is relatively large, the effect of preventing the penetration of moisture into the sealing resin by reducing the penetration of moisture is great. Therefore, in the present embodiment, a tape substrate 212 is used as a wiring board to which the sensor package 211 is attached as in the solid-state imaging device 210 shown in FIG. 34, and the base 213 of the tape substrate 212 is formed of a super heat resistant polyimide film. is doing. This super heat-resistant polyimide film can discharge the moisture absorbed by the sealing resin 214, so that the moisture in the sealing resin 214 can be reduced to suppress the occurrence of water vapor explosion. Moreover, since it is thinner than the glass epoxy substrate, it can contribute to the thinning of the solid-state imaging device 210.

  In addition, as a super heat-resistant polyimide film, for example, Kapton (registered trademark) film (trade name: US DuPont) is known and can be easily adopted.

  In each of the above embodiments, an epoxy resin is used as the sealing resin. However, in order to prevent the sealing resin from peeling off from the sensor package and the wiring board, a material having higher adhesion may be used. Good. As this highly adhesive resin, for example, a highly adhesive resin such as a bisphenol-based epoxy resin can be used. Moreover, when using this highly adhesive resin, it is preferable to use an amine or polyamine as the curing agent.

  The viscosity at the time of filling the sealing resin is preferably 100 Pas or less in consideration of screen printing suitability, potting suitability, void generation prevention, and the like. For example, when a sealing resin having a viscosity of about 450 Pas at room temperature is used, a viscosity of about 50 Pas can be obtained by heating to about 40 ° C. during filling. Also, a sealing resin having a low viscosity of about 50 Pas at room temperature may be used. In this case, it is advisable to adjust the viscosity by mixing a solvent with an optimized low-viscosity raw material.

  Moreover, in order to improve temperature cycling property, it is preferable to use sealing resin whose glass transition temperature (Tg) is 150 ° C. or more.

  In addition, as a cause of cracking or peeling of the sealing resin, the influence of thermal stress generated between the sealing resin, the sensor package, and the wiring board can be considered. For example, the thermal expansion coefficient (α) of the sealing resin (epoxy resin) 7 of the first embodiment is about 50 ppm / ° C. However, the thermal expansion coefficient of the imaging chip 19 and the spacer 22 formed of silicon is 3 ppm / ° C, the thermal expansion coefficient of the cover glass 6 is 6 ppm / ° C, and the thermal expansion coefficient of the wiring board 3 formed of glass epoxy. Is 13 to 17 ppm / ° C, which is much smaller than the thermal expansion coefficient of the sealing resin 7, so the difference in thermal expansion coefficient of each component during temperature cycle such as molding, reflow, PMC, and actual use As a result, thermal stress is generated, and the sealing resin 7 may be warped, distorted, or peeled off. In order to prevent this, the thermal expansion coefficient (α) of the sealing resin 7 is preferably 13 ppm / ° C. or less.

  Similarly, in order to reduce thermal stress, the sealing resin preferably has a flexural modulus of 28 GPa or less and a molding shrinkage of 0.12% or less. In order to keep the strength of the solid-state imaging device appropriate and prevent deformation, it is preferable that the hardness of the sealing resin is, for example, that Shore D has a hardness of 90 or more.

  Further, when the adhesive used for bonding the spacer 2 reaches the glass transition temperature during PMC, the spacer or the cover glass may be peeled off from the imaging chip. Therefore, it is preferable that the Tg of the adhesive is equal to or higher than the PMC temperature. When the thermal expansion coefficient of the sealing resin is low and the stress on the adhesive due to the thermal stress at high temperature is small, the glass transition temperature of the adhesive may be equal to or lower than the PMC temperature.

  In addition, thermal stress due to the difference in thermal expansion coefficient is also generated between the sensor package and the wiring board, which also causes cracking or peeling of the sealing resin. For example, the thermal expansion coefficient of the wiring board 3 made of glass epoxy is 13 to 17 ppm / ° C, the thermal expansion coefficient of the wiring board made of super heat-resistant polyimide film is 16 to 60 ppm / ° C, and the heat of the imaging chip Compared with an expansion coefficient of 3 ppm / ° C, the difference is quite large.

  In order to solve the above problem, it is preferable to use a die attach film having a glass transition temperature lower than the PMC temperature. Thereby, since the die attach film absorbs the distortion between the imaging chip and the wiring board during PMC, it is possible to prevent the sealing resin from being cracked and peeled off. The glass transition temperature of the die attach film is preferably, for example, about Tg = 50 to 80 ° C. and α = 80 to 100 ppm / ° C. so as to reach the glass transition temperature immediately after the start of PMC.

  In order to reduce the occurrence of water vapor explosion due to moisture absorption of the sealing resin, it is preferable to use a sealing resin having a water absorption rate of 0.3% by weight (saturated steam pressure test: 20 hours) or less. In order to prevent corrosion of the input / output pads of the sensor package, the water absorption rate of the sealing resin is more preferably 0.15% by weight or less.

  Further, as a method for further reducing the water absorption rate of the sealing resin 7, it is also effective to increase the filler filling rate in addition to using a resin having a low water absorption rate. For example, in the sealing resin 7 of the first embodiment, the filling rate of the filler such as silica was 73%, but the water absorption rate was not improved. Therefore, the present applicant manufactured a solid-state imaging device using a sealing resin with a filler filling rate of 80% or more, and conducted a reliability test of the JEDEC standard. A decrease in peeling could be confirmed. Therefore, it is preferable to use a sealing resin having a filler filling rate of 80% or more.

  Also, in order to increase the filling rate of the filler, sealing is performed by mixing two types of fillers, large coarse particles (for example, 55 μm in diameter) and small particles (for example, 20 μm in diameter). The resin may be filled. According to this, as shown in FIG. 35, since the fine particles 222 are accommodated in a small space generated by contact between the coarse particles 220, the filling rate of the filler in the sealing resin 223 is set to 80% or more. Can do.

  As the filling rate of the filler increases, the viscosity of the sealing resin increases, but if a low-viscosity raw material is optimized, a low-viscosity sealing resin with good screen printing and potting suitability Can be obtained.

  Further, as the sealing resin, it is preferable to use a low halogen, low alkali metal (for example, 10 ppm or less) sealing resin. Thereby, since the amount of ionic impurities eluted from the sealing resin is reduced, corrosion of the input / output pad can be prevented.

  Further, as the dam material used for forming the retaining wall in the potting process, the same resin system as the sealing resin described above is used so that cracks do not occur due to the difference in thermal expansion coefficient during the PMC process. Preferably, for example, it is desirable that the thermal expansion coefficient is 13 ppm ° / less or less, and the viscosity when forming the retaining wall is about 500 Pas.

  With the various improvements described above, cracking and peeling of the sealing resin are reduced, and the sealing performance in the space in which the image sensor is stored is also improved. At the same time, it is possible to prevent the bonding wire from coming off the pad, so that the malfunction of the solid-state imaging device can be reduced. For example, the solid-state imaging device according to the first embodiment is manufactured using a sealing resin in which the filler filling rate of the sealing resin is 80% or more and the thermal expansion coefficient is 12 ppm / ° C. or less. As a result of conducting a storage test and a temperature cycle test, 500 hours / 1000 cycles could be achieved. Further, in the solid-state imaging device using a super heat resistant polyimide film tape substrate as the wiring board, the reliability test could be cleared by the level 1 pretreatment.

  In addition, each improvement measure of the said embodiment can be used individually or in combination as appropriate. Moreover, although application to the solid-state imaging device of 1st Embodiment was demonstrated to the example, it is applicable also to the solid-state imaging device of 2nd-5th embodiment.

  In addition, although each said embodiment demonstrated the CCD type solid-state imaging device to the example, it can utilize also for manufacture of other solid-state imaging devices, such as a CMOS type. Moreover, although various package forms such as FLGA, FBGA, QFN, and SIP are used, the present invention can also be used to manufacture solid-state imaging devices in other package forms.

It is a perspective view which shows the external appearance shape of the solid-state imaging device manufactured using this invention. It is sectional drawing of a solid-state imaging device. It is a flowchart which shows the manufacture procedure of a solid-state imaging device. It is a flowchart which shows the manufacture procedure of a sensor package. It is explanatory drawing which shows the spacer formation process of a sensor package. It is explanatory drawing which shows the board | substrate joining and dicing process of a sensor package. It is a perspective view which shows the external appearance shape of a glass substrate and a silicon wafer. It is explanatory drawing which shows the manufacturing process of a solid-state imaging device. It is a perspective view showing the external shape of the assembly wiring board, It is the schematic which shows the structure of a vacuum screen printing apparatus. It is a top view of a stage. It is a perspective view which shows the attachment state of the mask to an assembly wiring board. It is a flowchart which shows the procedure of a printing process. It is explanatory drawing which shows the procedure of vacuum screen printing. It is sectional drawing which shows the example which covers a cover glass with a protection sheet. It is a perspective view which shows the external appearance shape of the solid-state imaging device of a FBGA package. It is sectional drawing of the solid-state imaging device of FBGA package. It is a flowchart which shows the manufacture procedure peculiar to the solid-state imaging device of a FBGA package. It is a perspective view which shows the external appearance shape of the solid-state imaging device of a QFN package. It is sectional drawing of the solid-state imaging device of a QFN package. It is a flowchart which shows the manufacture procedure peculiar to the solid-state imaging device of a QFN package. It is a perspective view which shows the external appearance shape of the solid-state imaging device using a system in package. It is sectional drawing of the solid-state imaging device using a stacked system in package. It is a flowchart which shows the procedure of a potting process. It is the schematic which shows the procedure of a potting process. It is sectional drawing which shows the solid-state imaging device resin-sealed by potting. It is sectional drawing which shows the solid-state imaging device which formed the chamfering part in the outer periphery of the cover glass. It is sectional drawing which shows the solid-state imaging device which formed the level | step-difference part in the outer periphery of the cover glass. It is sectional drawing which shows the solid-state imaging device which formed the rough surface in the side surface of a cover glass, a spacer, and an imaging chip. It is sectional drawing which shows the solid-state imaging device which formed the polyimide film on the upper surface of the imaging chip. It is sectional drawing which shows the solid-state imaging device which formed the nitride film in the outer peripheral surface of a cover glass, a spacer, and an imaging chip. It is sectional drawing which shows the solid-state imaging device which filled the inert gas in the space enclosed by the cover glass, the spacer, and the imaging chip. It is a flowchart which shows the timing which implements UV cleaning or plasma cleaning. It is sectional drawing which shows the solid-state imaging device using the tape board | substrate which consists of a super heat-resistant polyimide film as a wiring board. It is explanatory drawing which shows the filling state of the filler to resin for sealing.

Explanation of symbols

2, 78, 85, 98, 110, 142, 150, 160, 170, 180, 190, 200, 210 Solid-state imaging device 3, 80, 96, 111 Wiring board 4, 79, 86, 95, 116, 130, 151 161, 171, 181, 191, 201, 211 Sensor package 5, 88 Bonding wire 6, 99, 117, 140, 152, 162, 172, 186, 192, 202 Cover glass 7, 91, 97, 118, 138, 154, 164, 177, 184, 197, 214 Sealing resin 8, 81 External conductor pad 12 Internal conductor pad 19, 155, 174, 182, 194, 204 Imaging chip 20 Image sensor 21, 89 Input / output pad 22, 156 , 173, 185, 193, 203 Spacer 47, 131 Combined wiring board 51 Die attach film 54 Vacuum screen printing device 68 Mask 75 Protection sheet 82 Solder ball 92 Outer lead 102,115 AFE chip 103,114 DSP chip 104,112 Power supply chip 133 Dam material 134 Dam material syringe 135 Retaining wall 139 Syringe for sealing

Claims (33)

An assembly wiring board is provided with a sensor package including an imaging chip provided with an image sensor and an input / output pad and a cover member that is translucent and is attached to the imaging chip and seals the image sensor. A die bonding step for fixing to each of the plurality of fixing portions;
A wire bonding step of connecting each input / output pad and an internal electrode provided on the assembly wiring board corresponding to each sensor package with a bonding wire;
A protection step of covering the upper surface of each cover member with a mask;
A sealing step of sealing the outer periphery of each sensor package by vacuum screen printing a sealing resin on the assembly wiring board;
A method for manufacturing a solid-state imaging device, comprising: a separation process for cutting the assembly wiring board and the sealing resin for each sensor package. A sensor package including an imaging chip provided with an image sensor and an input / output pad, a light-transmitting cover member that is attached to the imaging chip and seals the image sensor, and cooperates with the sensor package A die bonding step of fixing at least one cooperating chip to each of a plurality of fixing portions provided on the assembly wiring board so that the upper surface of the cover member is not hidden by the cooperating chip;
A wire bonding step of connecting the input / output pads of each sensor package and cooperating chip and the internal electrodes provided on the collective substrate corresponding to each sensor package and cooperating chip with bonding wires;
A protection step of covering the upper surface of each cover member with a mask;
A sealing step of sealing the outer periphery of each sensor package by vacuum screen printing a sealing resin on the assembly wiring board;
A method of manufacturing a solid-state imaging device, comprising: a separate wiring step of cutting an assembly wiring board and a sealing resin into each sensor package and a corresponding cooperating chip corresponding thereto.   3. The solid according to claim 1, wherein the mask includes a mask portion that covers an upper surface of each cover member, and an outer wall portion that surrounds an outer periphery of the assembly wiring board and restricts a printing range of the sealing resin. Manufacturing method of imaging apparatus.   The mask is formed of a protective sheet that is larger than the image sensor and has an outer shape smaller than the upper surface of the cover member, and an edge of the protective sheet is formed between the edge of the image sensor and the upper edge of the cover member. The method for manufacturing a solid-state imaging device according to claim 1, wherein a protective sheet is attached to the upper surface of the cover member so as to be interposed therebetween.   5. The method of manufacturing a solid-state imaging device according to claim 4, wherein the mask includes an outer wall portion that surrounds an outer periphery of the assembly wiring board and restricts a printing range of the sealing resin.   The sealing step includes a step of screen-printing a sealing resin on the outer periphery of each sensor package at a first pressure lower than atmospheric pressure, and a second pressure higher than the first pressure and lower than atmospheric pressure. 6. The method of manufacturing a solid-state imaging device according to claim 1, further comprising a step of changing the pressure to atmospheric pressure and screen-printing a sealing resin again on the outer periphery of each sensor package.   7. The method of manufacturing a solid-state imaging device according to claim 6, wherein the first atmospheric pressure is 100 Pas or less, and the second atmospheric pressure is about 20000 to 90000 Pas. The die bonding step, the sensor package when secured to the fixed part of the assembly board, a manufacturing method of a solid-state imaging device according to any one of claims 1 to 7, characterized by the use of a film-like die attach material. After the sealing step, a method for manufacturing a solid-state imaging device having a mold curing step of heating and curing the sealing resin,
9. The method of manufacturing a solid-state imaging device according to claim 8 , wherein a glass transition temperature of the die attach material is lower than a heat curing temperature of the mold curing process. The method of manufacturing a solid-state imaging device according to claim 9 , wherein the die attach material has a glass transition temperature of 50 to 80 ° C and a thermal expansion coefficient of 80 to 100 ppm / ° C. After the sealing step, a method for manufacturing a solid-state imaging device having a mold curing step of heating and curing the sealing resin,
In the sensor package, a glass transition temperature of the adhesive used in attaching the imaging chip and the cover member, according to any one of claims 1 to 10, wherein the at heat curing temperature or higher of the mold curing step Manufacturing method of solid-state imaging device. Before the singulation process, a solid-state imaging of claims 1 to 11, wherein any one, characterized in that a external electrode forming step of forming an external electrode connected to the internal electrodes on the outside of the assembly board Device manufacturing method. 13. The solid-state imaging device according to claim 12 , wherein the collective wiring board is a substrate substrate, and the external electrode forming step includes a ball forming step of forming solder balls on the wiring of the substrate substrate. Production method. 13. The method of manufacturing a solid-state imaging device according to claim 12 , wherein the collective wiring board is a lead frame, and the external electrode forming step includes a plating step of plating an outer lead of the lead frame. The assembly board includes a method for manufacturing a solid-state imaging device of claims 1 to 12, wherein any one, characterized in that a tape substrate. 16. The method of manufacturing a solid-state imaging device according to claim 15 , wherein the tape substrate is formed of a super heat-resistant polyimide film. Wherein between the die bonding and the wire bonding step, the manufacturing method of the solid-state imaging device according to any one of claims 1 to 16, characterized in that the cleaning process is provided for cleaning the said sensor package and the assembly board. 18. The method of manufacturing a solid-state imaging device according to claim 17 , wherein the cleaning step uses UV cleaning. The method of manufacturing a solid-state imaging device according to claim 17 , wherein the cleaning step uses plasma cleaning. The sealing resin, a method for manufacturing a solid-state imaging device according to any one of claims 1 to 19, characterized in that in said sensor package to said circuit assembly board is highly adhesive resin having a dense adhesion . 21. The method of manufacturing a solid-state imaging device according to claim 20 , wherein a bisphenol-based epoxy resin is used as the high adhesion resin. The method for manufacturing a solid-state imaging device according to claim 21, wherein the curing agent used for the high-adhesion resin is an amine-based or polyamine-based one. The viscosity during the filling of the sealing resin, a method for manufacturing a solid-state imaging device according to any one of claims 1 to 22, characterized in that not more than 100 Pas. 24. The method of manufacturing a solid-state imaging device according to claim 23 , wherein the sealing resin is heated and filled. Thermal expansion coefficient of the sealing resin, 13 ppm / ° production method of claims 1 to 24 solid-state imaging device according to any one, characterized in that C or less. The flexural modulus of the sealing resin, a method for manufacturing a solid-state imaging device according to any one of claims 1 to 25, characterized in that not more than 28 GPa. The mold shrinkage factor of the sealing resin, a method for manufacturing a solid-state imaging device according to any one of claims 1 to 26, characterized in that 0.12% or less. The water absorption rate of the sealing resin, a method for manufacturing a solid-state imaging device according to any one of claims 1 to 27, characterized in that it is hereinafter 0.3 wt%. The sealing resin, a method for manufacturing a solid-state imaging device according to any one of claims 1 to 28, wherein the filling rate of the filler is 80% or more. 30. The method of manufacturing a solid-state imaging device according to claim 29, wherein the filler is a mixture of a first filler and a second filler having a smaller size than the first filler. Glass transition temperature of the sealing resin, the manufacturing method of claims 1 to 30 solid-state imaging device according to any one, characterized in that it is above 150 ° C. The hardness of the sealing resin, a method for manufacturing a solid-state imaging device of claims 1 to 31, wherein any one, characterized in that the Shore D of 90 or more. The sealing resin, the production method of halogen and a solid-state imaging device according 32 any one claims 1, wherein the content of the alkali metal is 10ppm or less, respectively.

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