JP2016031949A - Wafer level packaging structure and method of manufacturing the same - Google Patents

Abstract

Variations in device characteristics and reliability of a wafer level packaging structure due to variations in bonding layer shape and thickness are reduced. A method of manufacturing a wafer level packaging structure 1 composed of a plurality of wafers bonded via bonding layers 25 and 27, wherein a planar shape surrounding at least a part of an individual chip region in the wafer is provided. It includes a step of forming frame-like bonding layers 25 and 27 on the wafer by screen printing. The screen plate for forming the bonding layers 25 and 27 is provided with a pattern so that the corners of the outer periphery of the planar shape of the bonding layers 25 and 27 are rounded or formed by a plurality of obtuse angles. Yes. [Selection] Figure 1

Description

  The present invention relates to a wafer level packaging structure and a manufacturing method thereof.

  For example, semiconductor devices formed by microfabrication technology and thin film formation technology such as a pressure sensor, an infrared sensor, an acceleration sensor, and an optical scanner are known. Such a semiconductor device is called a MEMS (Micro Electro Mechanical Systems) device.

  In the manufacturing process of the MEMS device, the element of the MEMS device is formed on a silicon wafer, a glass wafer, or the like. After a plurality of wafers are bonded together by a bonding technique at the wafer level, the MEMS devices are divided into individual pieces. As a result, small, high-performance MEMS devices, for example, in the order of several thousand pieces from one wafer are packaged at low cost.

By using a glass frit paste as a bonding layer between wafers in a MEMS device, hermetic sealing can be realized by a simple method. Bonding using glass frit paste has a wide tolerance for the shape and cleanliness of the surface of the substrate to be bonded due to the thickness and flexibility of the bonding layer.
In addition, the glass frit can be formed by an independent process as a bonding layer, and has high flexibility in the process because of its good applicability to the preceding and subsequent manufacturing processes.

  In MEMS devices such as MEMS sensors and actuators, which are composed of microcavities bonded to multiple substrates, extremely precise control of the width and thickness of the bonding layer is required to ensure its performance and reliability. The

In order to apply the glass frit paste by patterning on the wafer, a screen plate and a screen printing machine are used.
FIG. 13 is a schematic plan view and cross-sectional view for explaining the screen printing technique.

  The screen plate 101 is, for example, a metal frame 103 with a stainless steel mesh 105 stretched. A part of the polymer emulsion having a thickness of several μm to several tens of μm (micrometer) applied so as to cover the entire surface of the mesh 105 is removed in an arbitrary pattern having a width of several tens of μm to several hundreds of μm to expose the mesh. .

  In the screen printing process, the paste 107 is placed on the mesh 105, and the squeegee 109 is pressed from the back of the paste 107 and moved in the direction of the arrow in the figure. Thereby, the paste 107 is applied to the wafer 111 through the exposed mesh pattern.

  In MEMS devices such as sensors and actuators, the glass frit printed pattern for hermetically sealing and bonding wafers to each other has a rectangular shape with a length of several hundred μm to several mm (millimeters) or a lattice with a period of several hundred μm to several mm. In many cases.

FIG. 14 is a schematic view for explaining a conventional glass frit pattern.
As shown in FIG. 14A, the glass frit pattern 203 for hermetically sealing the individual chip region 201 is formed on the peripheral portion and the peripheral portion of the individual chip region 201 and formed in a lattice pattern. Yes.

  As shown in FIG. 14B, the glass frit pattern 205 is formed in a frame-like rectangle along the peripheral edge of the individual chip region 201 so as to surround the central portion of the individual chip region 201. The glass frit pattern 205 is formed for each individual chip region 201. A frame-like glass frit pattern is disclosed in Patent Document 1, for example.

  14A and 14B, after the two wafers are bonded at the wafer level by the glass frit pattern 203 or 205, the center position between the adjacent individual chip regions 201 is determined by the dicing technique. The individual chip area 201 is divided by cutting.

  The frame-shaped rectangular glass frit pattern 205 requires less glass frit when compared to the lattice-shaped glass frit pattern 203 to obtain the same bonding width. Further, the glass frit pattern 205 has advantages such that the pattern parallel to the squeegee is not continuous over a wide range, so that the movement of the squeegee is stable and a good pattern shape can be obtained.

  When a screen plate having a frame-like rectangular pattern is used and printing is performed by moving the squeegee in a direction parallel to one side of the rectangle, as shown in FIG. 14B, a straight line is formed at the corner 207 of the glass frit pattern 205. The line width is wider than the portion 209. In addition, since the paste transmission state from the mesh changes discontinuously at the corner portion 207, there is a problem that the amount of paste applied varies greatly.

  For example, in MEMS sensors and actuators composed of microcavities, if the shape and thickness of the bonding layer changes depending on the location, the design and process will become difficult, and the characteristics will vary due to changes in sealing properties. Problems such as reduced reliability occur.

  An object of the present invention is to reduce variations in device characteristics and reliability of a wafer level packaging structure due to variations in the shape and thickness of a bonding layer.

  A method for manufacturing a wafer level packaging structure according to the present invention is a method for manufacturing a wafer level packaging structure composed of a plurality of wafers bonded via a bonding layer, and includes a method for manufacturing individual chip regions in a wafer. A step of forming the bonding layer having a frame shape in a plane shape surrounding at least a portion on a wafer by screen printing, and the screen plate for forming the bonding layer has a corner portion of the outer periphery of the bonding layer in a plane shape A pattern is provided so as to have a rounded shape or a shape constituted by a plurality of obtuse angles.

  The method for manufacturing a wafer level packaging structure of the present invention can reduce variations in device characteristics and reliability of the wafer level packaging structure due to variations in the shape and thickness of the bonding layer.

It is a schematic sectional view for explaining one embodiment of a wafer level packaging structure, and a plan view showing a formation position of a bonding layer. It is a schematic sectional drawing for demonstrating the manufacturing process of one Example of the manufacturing method of a wafer level packaging structure. FIG. 3 is a schematic cross-sectional view for explaining a step subsequent to FIG. 2 of the same example. It is a top view for demonstrating the planar shape of the joining layer formed on the wiring board by screen printing. It is a top view for demonstrating the planar shape of the joining layer formed on the element substrate by screen printing. It is the top view for demonstrating an example of the screen plate used for formation of a joining layer, and the top view which expands and shows the part. It is the top view for demonstrating the conventional screen plate used for formation of a joining layer, and the top view which expands and shows a part. It is the top view for demonstrating the other example of the screen plate used for formation of a joining layer, and the top view which expands and shows the part. It is a top view for demonstrating the further another example of the screen plate used for formation of a joining layer. FIG. 10 is a plan view for explaining paste permeation amounts at corners during screen printing for the screen plate shown in FIG. 9 and the conventional screen plate shown in FIG. 7. It is a top view for demonstrating the further another example of the screen plate used for formation of a joining layer. It is a top view for demonstrating the further another example of the screen plate used for formation of a joining layer. It is the schematic plan view and sectional drawing for demonstrating a screen printing technique. It is the schematic for demonstrating the conventional glass frit pattern.

  In the method for manufacturing a wafer level packaging structure according to the present invention, a bonding layer having a shape in which the corners of the outer periphery of the planar shape are rounded or formed by a plurality of obtuse angles is formed by screen printing. In the formed bonding layer, the change in the pattern width at the corners is smaller than when the corners on the outer periphery are perpendicular. As a result, variations in the shape and thickness of the bonding layer are reduced, and variations in device characteristics and reliability of the wafer level packaging structure due to variations in the shape and thickness of the bonding layer are reduced.

  In the method for manufacturing a wafer level packaging structure according to the present invention, for example, the pattern of the screen plate is configured with a rounded shape or a plurality of obtuse angles on the inner periphery of the planar shape of the bonding layer. You may make it form so that it may become a shape. However, the pattern of the screen plate may be formed such that the corners of the inner periphery of the planar shape of the bonding layer are at right angles.

  The bonding layer may be formed with a uniform width over the entire circumference, for example. Thereby, the dispersion | variation in the shape and thickness of the joining layer formed by screen printing is reduced. However, in the present invention, the bonding layer may not be formed with a uniform width.

  An example in which the bonding layer is a glass frit can be given. By reducing the variation in the shape and thickness of the glass frit, the flow of the glass frit is stabilized over the entire circumference of the glass frit when two wafers are pressure-bonded via the glass frit, and is uniformly thermocompressed. The For example, when the glass frit is formed with a uniform width over the entire circumference, the flow of the glass frit during pressurization is uniform over the entire circumference, which is particularly effective. The bonding layer is not limited to glass frit. The bonding layer may be any material that can be formed by screen printing and can bond between wafers.

  Further, the pattern of the screen plate is a substantially rectangular shape having a frame shape in a plane shape, and the corner portion arranged on the upstream side of the squeegee movement at the screen printing out of the corner portions on the outer periphery of the pattern is on the downstream side. You may make it form large compared with the corner | angular part arrange | positioned. Such a plane shape of the pattern of the screen plate can adjust the transmission state of the paste evenly on the upstream side and the downstream side during screen printing. Thereby, the flow of the bonding layer (for example, glass frit) when the two wafers are pressure-bonded is made uniform in the individual chip region, and the two wafers are evenly thermocompression bonded. In addition, when the planar shape is a frame-like substantially rectangular shape, the shape of all the corners may be the same, or any one or more of the four corners may be the pattern of the screen plate. The shape of the corner may be different from the shape of the other corner.

  A wafer level packaging structure according to the present invention is a wafer level packaging structure composed of a plurality of wafers bonded via a bonding layer, and the bonding layer is formed by screen printing. The planar shape of the bonding layer is a frame shape that surrounds at least a part of the individual chip region in the wafer, and the corners of the outer periphery of the planar shape of the bonding layer are configured with a rounded shape or a plurality of obtuse angles. It is characterized by having a different shape.

  In the wafer level packaging structure of the present invention, the outer peripheral corner of the planar shape of the bonding layer has a rounded shape or a shape composed of a plurality of obtuse angles, so that the outer peripheral corner is a right angle. The change in the pattern width at the corner is smaller than in some cases. This reduces variations in the shape and thickness of the bonding layer formed by screen printing, and reduces variations in device characteristics and reliability of the wafer level packaging structure due to variations in the shape and thickness of the bonding layer. Is done.

  In the wafer level packaging structure of the present invention, for example, the inner peripheral corner of the planar shape of the bonding layer is formed to have a rounded shape or a shape constituted by a plurality of obtuse angles. It may be. However, the corner of the inner periphery of the planar shape of the bonding layer may be a right angle.

  In the wafer level packaging structure of the present invention, the bonding layer may be formed with a uniform width, for example, over the entire circumference. Thereby, the dispersion | variation in the shape and thickness of the joining layer formed by screen printing is reduced. However, in the wafer level packaging structure of the present invention, the bonding layer may not be formed with a uniform width.

  In the wafer level packaging structure of the present invention, an example in which the bonding layer is a glass frit can be given. The operation and effect when the bonding layer is a glass frit in the wafer level packaging structure of the present invention is the same as the above operation and effect when the bonding layer is a glass frit in the manufacturing method of the wafer level packaging structure of the present invention. It is the same. In the wafer level packaging structure of the present invention, the bonding layer is not limited to glass frit. The bonding layer may be any material that can be formed by screen printing and can bond between wafers.

  Further, in the wafer level packaging structure of the present invention, the planar shape of the bonding layer is, for example, a frame-like substantially rectangular shape, and two linear portions for at least one of the two opposing two sides. The lengths may be different from each other. Such a bonding layer is a frame in which corners arranged on the upstream side of the squeegee movement in the corners on the outer periphery of the pattern are formed larger than corners arranged on the downstream side. Can be formed by using a screen plate having a substantially rectangular pattern. The operation and effect of this aspect are the same as the above operation and effect when the above-described screen plate is used in the method for manufacturing a wafer level packaging structure of the present invention. In the wafer level packaging structure of the present invention, when the planar shape of the bonding layer is a frame-like substantially rectangular shape, even if the length of the straight portion is the same for every two opposing sides. The lengths of the straight portions on the four sides may be the same.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view for explaining an embodiment of a wafer level packaging structure and a plan view showing positions where bonding layers are formed. In FIG. 1, the cross-sectional view corresponds to the position AA in the plan view. In the plan view of FIG. 1, only the outline of the wafer level packaging structure and the bonding layer are shown.

  The wafer level packaging structure 1 is, for example, a MEMS sensor. The wafer level packaging structure 1 includes an element substrate 3, a wiring substrate 5, and a cover substrate 7.

  The element substrate 3 is formed from, for example, a silicon substrate having a thickness of 400 μm. The element substrate 3 includes an element 9 formed by a MEMS manufacturing technique. The element 9 is, for example, a sensor formed by a microfabrication technique, an actuator such as a vibrator, and is an optical sensor in this embodiment.

  The element substrate 3 also includes an element drive circuit 11 and an electrode pad 13 formed by a semiconductor manufacturing technique. The element drive circuit 11 controls the operation of the element 9. The element drive circuit 11 includes, for example, a transistor, a resistance element, a metal wiring, and the like. The electrode pad 13 is an electrode pad that serves as an electrical contact with the outside for driving the element 9. The electrode pad 13 is made of, for example, aluminum or an aluminum alloy.

  The wiring substrate 5 is used to draw out the potential of the electrode pad 13 of the element substrate 3 to the outside of the wafer level packaging structure 1. The wiring substrate 5 includes an element substrate side electrode pad 15, a through electrode 17, and an external side electrode pad 19. The wiring substrate 5 is formed of a glass substrate having a thickness of 400 μm, for example. The substrate material of the wiring board 5 may be other insulating substrates such as ceramics.

  The element substrate side electrode pad 15 is formed on the surface of the wiring substrate 5 facing the element substrate 3. For example, the element substrate side electrode pad 15 has a structure in which a Cr thin film, a Pt thin film, and an Au thin film are laminated in this order from the wiring substrate 5 side. The Cr thin film improves the adhesion with the surface of the wiring substrate 5 (for example, glass). The Pt thin film prevents diffusion of the Cr thin film. The Au thin film is for conducting.

  The through electrode 17 is formed in a through hole provided in the wiring substrate 5 so as to penetrate from the surface facing the element substrate 3 to the opposite surface. The through electrode 17 is made of, for example, tungsten. The through electrode 17 is electrically connected to the element substrate side electrode pad 15.

  The external electrode pad 19 is formed on the surface of the wiring substrate 5 opposite to the surface facing the element substrate 3. The configuration of the external electrode pad 19 is the same as the configuration of the element substrate side electrode pad 15, for example. The external electrode pad 19 is electrically connected to the element substrate side electrode pad 15 through the through electrode 17.

  In addition, the element substrate side electrode pad 15 and the external side electrode pad 19 are not limited to the above-described configuration of the through electrode 17. For example, as the diffusion preventing layer of the electrode pad, a Ni thin film or the like can be used in addition to the Pt thin film. Further, a Ti thin film or the like can be used as an adhesion layer with the surface of the wiring board 5. Further, the material of the through electrode 17 is not limited to Au, and may be another conductive material.

  The cover substrate 7 is for hermetically sealing the element 9. The cover substrate 7 is formed of a silicon substrate having a thickness of 600 μm, for example.

  The cover substrate 7 includes, for example, an optical element 21 on the surface opposite to the surface facing the element substrate 3. The optical element 21 is a diffraction grating formed by, for example, a thin film process. The optical element 21 is not limited to a diffraction grating, and may be another optical element such as a lens or a filter. The optical element 21 may be formed on any one of the surface of the cover substrate 7 facing the element substrate 3, the opposite surface, or both surfaces. Further, the cover substrate 7 may not have an optical function.

A connection terminal 23 and a bonding layer 25 are disposed between the element substrate 3 and the wiring substrate 5.
The connection terminal 23 electrically connects the electrode pad 13 formed on the element substrate 3 and the element substrate side electrode pad 15 formed on the wiring substrate 5. The connection terminal 23 is made of a flexible conductive material such as Au or Ag.

  The bonding layer 25 is for bonding the element substrate 3 and the wiring substrate 5. The bonding layer 25 is, for example, a glass frit. The element substrate 3 and the wiring substrate 5 are spaced from each other depending on the thickness of the bonding layer 25. As a result, the element 9 of the element substrate 3 can be prevented from receiving interference from the wiring substrate 5. The bonding layer 25 is arranged in a frame shape along the periphery of the element substrate 3 and the wiring substrate 5 so as not to overlap with the element 9, for example, so as to have an interval of at least 50 μm from the element 9.

  A bonding layer 27 is disposed between the element substrate 3 and the cover substrate 7. The bonding layer 27 is for bonding the element substrate 3 and the cover substrate 7 together. The bonding layer 27 is, for example, a glass frit. The element substrate 3 and the cover substrate 7 are arranged at intervals. The bonding layer 27 is arranged in a frame shape along the periphery of the element substrate 3 and the cover substrate 7.

  For example, the wiring substrate 5 and the cover substrate 7 are bonded to the element substrate 3 by the bonding layers 25 and 27 under reduced pressure conditions. Thereby, the element 9 formed on the element substrate 3 is hermetically sealed.

  The bonding layers 25 and 27 are respectively formed by screen printing. The planar shape of the bonding layers 25 and 27 is a frame-like substantially rectangular shape. The outer peripheral corners and the inner peripheral corners of the bonding layers 25 and 27 are rounded so that the width dimensions of the bonding layers 25 and 27 are uniform over the previous week. The width dimension of the bonding layers 25 and 27 is, for example, 150 μm.

  The thickness of the bonding layer 25 is 20 μm, for example. The maximum height of the protrusion on the surface of the wiring substrate 5 facing the element substrate 3 is, for example, 10 μm, and the thickness of the bonding layer 25 is set to be thicker than that. The thickness of the bonding layer 27 is, for example, the same as the thickness of the bonding layer 25 and is 20 μm.

  The bonding layers 25 and 27 are formed using, for example, the same screen plate (screen plate). By setting the planar shape and thickness to the same settings for the bonding layers 25 and 27, the bonding layers 25 and 27 can be formed under a common screen plate and printing conditions, respectively, so that manufacturing costs can be reduced.

  2 and 3 are schematic cross-sectional views for explaining a manufacturing process of an embodiment of a method for manufacturing a wafer level packaging structure. The numbers in parentheses in FIGS. 2 and 3 correspond to the numbers in parentheses in steps (1) to (8) described below. FIG. 4 is a plan view for explaining the planar shape of the bonding layer formed on the wiring board by screen printing. FIG. 5 is a plan view for explaining the planar shape of the bonding layer formed on the element substrate by screen printing. An embodiment of the manufacturing method will be described with reference to FIGS.

(1) The element 9, the element drive circuit 11, and the electrode pad 13 are formed for each individual chip region 1a on the element substrate wafer 3a by a fine processing process and a semiconductor thin film process. The electrode pad 13 is formed in a laminated structure composed of three layers of Au / Pt / Cr in the order of the element substrate wafer 3a, for example, by a sputtering film forming technique. On the element substrate wafer 3a, a plurality of individual chip regions 1a are arranged in a matrix, for example. Between adjacent individual chip areas 1a, a planned cutting area 29 called a scribe line is provided.

  The element substrate wafer 3a is, for example, a silicon wafer having a thickness of 400 μm. However, the element substrate wafer 3a is not limited to a silicon wafer, and other wafers such as an SOI (Silicon on Insulator) wafer in which an oxide film layer is interposed may be used.

(2) The connection terminals 23 are printed in a dot shape by screen printing in accordance with the positions of the electrode pads 13 of the element substrate wafer 3a. The connection terminal 23 is, for example, Ag paste. In order to remove the solvent and the binder, the printed Ag paste is heated to 200 ° C. in the atmosphere and sufficiently heated and fired. Although Ag paste is used here, porous Au or the like may be used as a flexible conductor.

  The thickness of the connection terminal 23 after the heating and baking treatment is, for example, 20 μm. The thickness of the connection terminal 23 is such that the electrode pad 13 and the element substrate formed when the element substrate wafer 3a and the wiring substrate wafer 5a (see FIG. 2 (5)) are bonded by the bonding layer 25 in the step (5) described later. It is set to be thicker than the interval between the side electrode pads 15. The dot diameter of the connection terminal 23 is set smaller than the planar size of the electrode pad 13 and is, for example, 150 μm.

(3) The element substrate side electrode pad 15 and the external side electrode pad 19 are formed at positions where the through electrodes 17 on both surfaces of the wiring board wafer 5a in which the through electrodes 17 made of tungsten are formed are exposed. The base material of the wiring board wafer 5a is, for example, glass. The element substrate side electrode pad 15 and the external side electrode pad 19 are composed of, for example, three layers of Au / Pt / Cr by sputtering film deposition in order from the surface side of the wiring substrate wafer 5a, like the electrode pad 13 of the element substrate 3. The

(4) The bonding layer 25 is formed for each individual chip region 1a by screen printing on the surface of the wiring substrate wafer 5a on which the element substrate side electrode pads 15 are formed. The bonding layer 25 is, for example, a glass frit. A glass frit paste is printed by screen printing, dried and baked to remove the solvent and the binder, and subjected to a heat treatment at, for example, 400 ° C. or more to be vitrified.

  As shown in FIG. 4, the pattern of the bonding layer 25 is formed along the peripheral edge of the individual chip region 1a. The planar shape of the bonding layer 25 is a frame-like substantially rectangular shape. When the bonding layer 25 is laid out so as to surround the arrangement positions of the element 9, the element driving circuit 11, the electrode pad 13, and the element substrate side electrode pad 15 in the individual chip region 1 a when viewed in plan, the element 9 is hermetically sealed. It is possible to stop. In FIG. 4, illustration of the element substrate side electrode pad 15 and the like is omitted.

The outer peripheral corner and the inner peripheral corner of the planar shape of the bonding layer 25 are rounded. The bonding layer 25 is formed with a uniform width over the entire circumference.
The bonding layer 25 has the same width over the entire circumference of the pattern, and the direction of the width gradually changes in the direction of 90 degrees. That is, the paste transmission state at the time of screen printing becomes continuous, and the application state such as the thickness and width dimension of the paste is stabilized. Therefore, variation in shape such as thickness and width dimension is reduced between the plurality of bonding layers 25 and in each bonding layer 25.

(5) The element substrate wafer 3a on which the connection terminal 23 for electrical connection is formed on the electrode pad 13 and the wiring substrate wafer 5a on which the bonding layer 25 for hermetic sealing bonding is formed are aligned. After that, thermocompression bonding is applied under high temperature. The element substrate wafer 3 a and the wiring substrate wafer 5 a are bonded via the bonding layer 25. The electrode pad 13 and the element substrate side electrode pad 15 are electrically connected via the connection terminal 23. Since the shape such as the thickness and the width dimension of the bonding layer 25 before bonding is stable, the flow of the bonding layer 25 at the time of thermocompression bonding becomes uniform between the plurality of individual chip regions 1a, and all the bonding layers 25 The circumference becomes uniform, and the state of the bonding layer 25 after bonding becomes uniform. Thereby, the sealing performance between the element substrate wafer 3a and the wiring substrate wafer 5a is stabilized.

(6) The second bonding layer 27 is printed by screen printing on the surface of the element substrate wafer 3a opposite to the surface bonded to the wiring substrate wafer 5a. Thereafter, drying and baking are performed to remove the solvent and the binder, and heat treatment at 400 ° C. or higher is performed to vitrify the bonding layer 27.

  For example, the same screen plate as that used when forming the bonding layer 25 is used, and the bonding layer 27 is formed under the same printing conditions. As a result, as shown in FIG. 5, the bonding layer 27 having a shape in which the outer peripheral corners and the inner peripheral corners of the planar shape are rounded is formed. Variations in shapes such as thickness and width are reduced between the plurality of bonding layers 27 and in each bonding layer 27. In FIG. 5, illustration of the element 9 and the like is omitted.

(7) Prepare the cover substrate wafer 7a on which the optical element 21 is formed using, for example, a thin film process. The optical element 21 is formed in all the individual chip regions 1a.

(8) The element substrate wafer 3a on which the bonding layer 27 for hermetic sealing bonding is formed and the cover substrate wafer 7a on which the optical element 21 is formed are aligned, and a load is applied at a high temperature. Thermocompression bonding. The setting of the bonding temperature at this time is set higher than the temperature of the thermocompression bonding of the bonding layer 25.

  The element substrate wafer 3 a and the cover substrate wafer 7 a are bonded via the bonding layer 27. Since the shape such as the thickness and width dimension of the bonding layer 27 before bonding is stable, the flow of the bonding layer 27 at the time of thermocompression bonding becomes uniform among the plurality of individual chip regions 1a, and all of the bonding layers 27 are all formed. The circumference becomes uniform, and the state of the bonding layer 27 after bonding becomes uniform. Thereby, the sealing performance between the element substrate wafer 3a and the cover substrate wafer 7a is stabilized.

  After that, the planned cutting area 29 is cut and the individual chip area 1a is cut out, whereby the wafer level packaging structure 1 is separated (see FIG. 1).

  FIG. 6 is a plan view for explaining an example of a screen plate used for forming the bonding layer and a plan view showing an enlarged part thereof. FIG. 7 is a plan view for explaining a conventional screen plate used for forming a bonding layer and a plan view showing an enlarged part thereof.

  As shown in FIG. 7, the corner portion 305 of the rectangular pattern 303 of the screen plate 301 has an outer periphery and an inner periphery at right angles. Therefore, the lengths of the width dimension 307a of the linear portion 307 and the width dimension 305a of the corner portion 305 of the rectangular pattern 303 are different. Therefore, at the corner portion 305, more paste is transmitted through the mesh onto the application target during screen printing. Further, the discontinuous change in the width dimension causes the paste transmission state to change abruptly, so that the application state such as the thickness and width of the paste at the corner 305 becomes unstable.

  As shown in FIG. 6, the corner portion 35 of the substantially rectangular pattern 33 of the screen plate 31 has a rounded outer periphery and inner periphery. The width dimension 37a of the linear portion 37 and the width dimension 35a of the corner portion 35 of the substantially rectangular pattern 33 are the same length. That is, the substantially rectangular pattern 33 is formed with a uniform width all around. The substantially rectangular pattern 33 has the same width over the entire circumference of the pattern, and the direction of the width gradually changes in the 90 degree direction. Therefore, the transmission state of the paste during screen printing is continuous, and the application state such as the thickness and width dimension of the paste applied on the application target is stabilized.

  By using the screen plate 31 of FIG. 6 to form the bonding layers 25 and 27 (see FIG. 1), the screen plate 301 of FIG. 7 is used in a plurality of bonding layers or individual bonding layers that are printed simultaneously. Compared to the case, variations in shape such as thickness and width are reduced.

  FIG. 8 is a plan view for explaining another example of the screen plate used for forming the bonding layer and a plan view showing an enlarged part thereof.

  The corner 45 of the substantially rectangular pattern 43 of the screen plate 41 is configured with a plurality of obtuse angles on the outer periphery and inner periphery. The width dimension 47a of the linear portion 47 of the substantially rectangular pattern 43 and the width dimension 45a of the 45 degree linear portion of the corner portion 45 have the same length. Further, the width dimension 45b of the boundary of the corner portion 45 is larger than the width dimension 47a of the straight portion 47, but smaller than the width dimension 305a of the corner portion 305 of FIG. As described above, in the substantially rectangular pattern 43, the pattern width gradually changes in the direction of 90 degrees, so that the paste transmission state at the time of screen printing is continuous, and the thickness of the paste applied on the application target is Application state such as width dimension is stabilized.

  FIG. 9 is a plan view for explaining still another example of the screen plate used for forming the bonding layer.

  The corner portions 55 and 57 of the substantially rectangular pattern 53 of the screen plate 51 are configured with a plurality of obtuse angles on the outer periphery and the inner periphery in the same manner as the corner portion 45 shown in FIG. The size of the substantially rectangular pattern 53 is different between the upstream corner portion 55 and the downstream corner portion 57 (the arrow in the figure is the moving direction of the squeegee during printing) during screen printing. In this example, the corner 55 is formed larger than the corner 57. The length of the 45-degree straight line portion of the corner portion 55 is larger than the length of the 45-degree straight portion of the corner portion 57. In a substantially rectangular pattern, the paste transmission state changes between the corner portion arranged on the upstream side and the corner portion arranged on the downstream side during screen printing. Accordingly, by forming an asymmetric pattern like the corners 55 and 57 in accordance with this, the application state such as the thickness and width of the paste at this portion can be further stabilized.

  FIG. 10 is a plan view for explaining the paste permeation amount at the corners during screen printing for the screen plate shown in FIG. 9 and the conventional screen plate shown in FIG.

  As shown in FIG. 10A, the corner portion 305 of the rectangular pattern 303 of the screen plate 301 has an outer periphery and an inner periphery at right angles. Therefore, in the corner portion 305 arranged on the upstream side of the movement of the squeegee 109, the paste permeation amount is larger in the region 309 having no pattern on the upstream side than the region 311 in the downstream corner portion 305.

  As shown in FIG. 10B, the corner portions 55 and 57 of the substantially rectangular pattern 53 of the screen plate 51 are configured with a plurality of obtuse angles on the outer periphery and the inner periphery. In the corner portion 55 arranged on the upstream side of the movement of the squeegee 109, the outer periphery of the substantially rectangular pattern 53 is inclined with respect to the squeegee 109 in the region 59 where there is no pattern on the upstream side. Transparent. As a result, the amount of paste transmitted through the region 59 of the corner 55 of the screen plate 51 is smaller than the amount of paste transmitted through the region 309 of the corner 305 of the screen plate 301. Therefore, the screen plate 51 can stabilize the application state such as the thickness and width dimension of the paste applied on the application target.

  This effect is also obtained in the screen plate 31 shown in FIG. 6 and the screen plate 41 shown in FIG. In the screen plate 51, the upstream corner portion 55 is formed larger than the downstream corner portion 57, and when the squeegee 109 moves on the corner portion 55, the outer periphery of the substantially rectangular pattern 53 is the squeegee 109. Since the portion inclined with respect to is larger, the effect can be obtained more remarkably.

FIG. 11 is a plan view for explaining still another example of the screen plate used for forming the bonding layer.
The corner 65 of the substantially rectangular pattern 63 of the screen plate 61 has a round outer periphery and a right inner periphery. The width dimension of the straight part 67 and the width dimension of the corner part 65 of the substantially rectangular pattern 63 are the same length.

FIG. 12 is a plan view for explaining still another example of the screen plate used for forming the bonding layer.
The corner portion 75 of the substantially rectangular pattern 73 of the screen plate 71 has a plurality of obtuse angles on the outer periphery and a right angle on the inner periphery. The corner 75 includes a portion having a width dimension equal to the width dimension of the linear portion 77 and a portion having a width dimension larger than the width dimension of the linear portion 77 and smaller than the width dimension 305a of the corner portion 305 in FIG. I have.

  As described above, the pattern of the screen plate used for forming the bonding layer in the present invention only needs to have a rounded shape or a plurality of obtuse angles on the outer periphery of the planar shape of the bonding layer. Further, the corner of the pattern has a difference between the width of the corner and the width of the straight portion, and the maximum width of the corner in the frame-like rectangular pattern (width 305a of the corner 305 in FIG. 7). Any shape can be used as long as it is smaller than the difference between the width dimension of the linear portion. In addition, in the corner | angular part of the said pattern, the part of the width dimension smaller than the width dimension of a linear part may exist.

  By using a screen plate having such a pattern, variations in shape such as the thickness and width of the bonding layer can be reduced as compared to the case of using a conventional screen plate in which the corners of the pattern are perpendicular. .

  Moreover, when the outer periphery and the inner periphery are configured with a plurality of obtuse angles, the number of obtuse angles in the inner periphery and the outer periphery is not particularly limited. For example, the number of obtuse angles on the inner periphery and the number of obtuse angles on the outer periphery may be different from each other.

  Further, the corners of the pattern of the screen plate may be a combination of a rounded shape and a straight line portion.

  As mentioned above, although the Example of this invention was described, the numerical value, material, arrangement | positioning, number, etc. in the said Example are examples, This invention is not limited to these, It was described in the claim Various modifications are possible within the scope of the present invention.

  For example, in the above embodiment, three wafers are bonded using two bonding layers, but the present invention is not limited to this. The present invention is applicable to any wafer level packaging structure including a structure in which two wafers are bonded via a bonding layer and a method for manufacturing the same.

  Moreover, in the said Example, although the joining layers 25 and 27 are formed along the peripheral part of the separate chip area | region 1a, this invention is not limited to this. In the present invention, a part or all of the bonding layer may be arranged at a position spaced from the peripheral edge of the individual chip region.

  Further, in the method for manufacturing a wafer level packaging structure according to the present invention, the bonding layer may be formed so that a part or all of the outer periphery of the bonding layer protrudes from the individual chip region and is disposed in the region to be cut. In this case, when cutting the planned cutting region and cutting out the individual chip region, a part or all of the rounded shape of the bonding layer or the shape constituted by a plurality of obtuse angles is removed.

  In the above embodiment, the bonding layers 25 and 27 are formed under the same printing conditions using the same screen plate, but the method for manufacturing the wafer level packaging structure of the present invention is not limited to this. In the method for manufacturing an air-level packaging structure including a plurality of bonding layers, the present invention may form the bonding layers using the same screen plate or different screen plates. May be.

1 Wafer Level Packaging Structure 1a Individual Chip Region 3a Element Substrate Wafer 5a Wiring Substrate Wafer 7a Cover Substrate Wafer 25, 27 Bonding Layers 35, 45, 55, 65, 75 Corners

Japanese Patent No. 3567793

Claims (10)

In a manufacturing method of a wafer level packaging structure composed of a plurality of wafers bonded via a bonding layer,
Forming a bonding layer having a frame-like planar shape surrounding at least a part of an individual chip region in the wafer on the wafer by screen printing;
The screen plate for forming the bonding layer is provided with a pattern such that corners of the outer periphery of the planar shape of the bonding layer have a rounded shape or a shape constituted by a plurality of obtuse angles. A method for manufacturing a wafer level packaging structure.   The said pattern of the said screen plate is formed so that the corner | angular part of the internal periphery of the planar shape of the said joining layer may also become a round shape or the shape comprised by the some obtuse angle. Manufacturing method of wafer level packaging structure.   The method for manufacturing a wafer level packaging structure according to claim 1, wherein the bonding layer is formed with a uniform width over the entire circumference.   The method for manufacturing a wafer level packaging structure according to any one of claims 1 to 3, wherein the bonding layer is a glass frit. The pattern of the screen plate is a substantially rectangular shape whose plane shape is a frame shape,
5. The corner portion disposed on the upstream side of the squeegee movement during the screen printing among the corner portions on the outer periphery of the pattern is formed larger than the corner portion disposed on the downstream side. The manufacturing method of the wafer level packaging structure as described in any one of these. In a wafer level packaging structure composed of a plurality of wafers bonded via a bonding layer,
The bonding layer is formed by screen printing,
The planar shape of the bonding layer is a frame shape surrounding at least a part of the individual chip area in the wafer,
The wafer level packaging structure according to claim 1, wherein a corner portion of the outer periphery of the planar shape of the bonding layer has a rounded shape or a shape constituted by a plurality of obtuse angles.   7. The wafer level packaging structure according to claim 6, wherein an inner peripheral corner portion of the planar shape of the bonding layer is also formed in a rounded shape or a shape constituted by a plurality of obtuse angles.   The wafer level packaging structure according to claim 6 or 7, wherein the bonding layer is formed with a uniform width over the entire circumference.   The wafer level packaging structure according to claim 6, wherein the bonding layer is a glass frit.   The planar shape of the joining layer is a frame-like substantially rectangular shape, and the lengths of the linear portions of the two sides are different from each other for at least one of the two pairs of opposing sides. The wafer level packaging structure as described in any one of Claims.

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