1. Field of the Invention
The present invention relates to semiconductor devices and methods for manufacturing the same. In particular, the present invention relates to a semiconductor device and a method for manufacturing the same that prevent deformation or cracking caused by a difference in coefficient of thermal expansion so as to ensure a proper electrical connection between electronic components or between an electronic component and a base substrate.
2. Description of the Related Art
In the field of semiconductor devices in recent years, a technology of densification is developing by means of stacking a plurality of bare chips (electronic components) in a single package. There are several known packaging techniques for connecting electrodes of the plurality of bare chips to electrodes of a base substrate on which the bare chips are mounted. For example, such packaging techniques include a wire-bonding packaging technique in which the electrodes are connected using gold wires, a flip-chip packaging technique in which the bare chips are flipped over to face downward so that the electrodes are connected via bumps provided on the functional faces of the bare chips, and a stacked packaging technique in which the electrodes are connected via bumps provided in the bare chips having a multilayered structure. These packaging techniques are discussed in, for example, Japanese Unexamined Patent Application Publication No. 11-274375.
According to Japanese Unexamined Patent Application Publication No. 11-274375, the chips are formed using, for example, an underfill material and/or a die-bond material. Moreover, a substrate, the die-bond material, the underfill material, and a sealing resin material have predetermined relationships among one another in view of coefficient of thermal expansion and glass-transition temperature so as to reduce stress induced as a result of thermal stress and to prevent connection failures in soldered areas caused by, for example, separation or cracking.
Manufacturing a semiconductor device using the known packaging techniques mentioned above has the following problems.
Since a matching inspection for the above-referenced semiconductor device is easily affected by line impedance between the electrodes, the inspection must be performed in an end-product state, which means that all of the bare chips have to be set in predetermined positions and be in an electrically connected state. Therefore, even in a case where only some of the bare chips are mismatched, all of the bare chips will be determined to be defective. In other words, the semiconductor device, which is the end product, will be determined to be defective, meaning that the entire semiconductor device has to be discarded. This is problematic in that the yield rate is lowered, thus resulting in high manufacturing costs.
If only the mismatched bare chips can be replaced with new ones, the other bare chips do not need to be discarded. An ability to achieve this can prevent a waste of bare chips and thus contributes to lower manufacturing costs.
However, a process for separating at least one of the bare chips from the other bare chips, which are physically connected to each other with, for example, wires or electrically conductive adhesives, is extremely complicated, and thus leads to high manufacturing costs.
Moreover, Japanese Unexamined Patent Application Publication No. 11-274375 does have any descriptions related to materials that satisfy conditions with regard to coefficient of thermal expansion and glass-transition temperature, or in other words, has no detailed examples with regard to the substrate, the die-bond material, the underfill material, the sealing resin material, an electrically conductive adhesive, and so on. Therefore, even though the invention set forth in Japanese Unexamined Patent Application Publication No. 11-274375 may be theoretically correct, the semiconductor device according to such an invention is impractical and is actually difficult to manufacture.
Accordingly, it is an object of the present invention to provide a semiconductor device that allows for a matching inspection during a manufacturing process thereof in a state similar to the actual end product of the device.
Furthermore, it is another object of the present invention to provide a semiconductor device and a method for manufacturing the device in which, if a mismatch of bare chips is determined in an inspection step during a manufacturing process, at least one of the mismatched bare chips (electronic components) can be readily replaced with a new one.
Furthermore, it is another object of the present invention to provide a semiconductor device that compensates for displacement caused by a difference in coefficient of thermal expansion between the bare chips or between the bare chips and a base substrate so as to prevent separation or cracking in electrode connection areas.
According to one aspect of the present invention, a semiconductor device includes an electronic component provided with a plurality of electrodes; a base substrate having a plurality of pattern electrodes disposed on a surface thereof; and an interposer whose upper and lower surfaces are both provided with a plurality of elastic contacts, the elastic contacts on the upper surface being electrically connected to the elastic contacts on the lower surface. The electrodes of the electronic component are electrically connected to the pattern electrodes of the base substrate via the interposer.
In this aspect of the present invention, the elastic contacts are elastically biased against the electrodes instead of being fixed to the electrodes. Consequently, even in a case where the positional relationship between the elastic contacts and the electrodes is subject to relative displacement due to a difference in coefficient of thermal expansion, the elastic contacts can be slid against the electrodes so as to be continuously elastically biased against the electrodes. Thus, the electrical connection between the elastic contacts and the electrodes can be maintained.
Furthermore, the semiconductor device may further include at least one electronic component stacked above the electronic component, such that the at least one electronic component of an upper layer and the electronic component of a lower layer are electrically connected to each other via an interposer disposed therebetween.
Accordingly, the electrodes of the at least one electronic component of the upper layer are constantly electrically connected to the electrodes of the electronic component of the lower layer.
For example, the interposer may include an insulating base having a plurality of through holes, and electric conductors embedded in the through holes. The elastic contacts are preferably disposed on opposite end surfaces of electric conductors.
In this case, the base is preferably composed of silicon or polyimide.
Accordingly, the coefficient of thermal expansion of the base is the same as or similar to those of the electronic component and the base substrate, thereby reducing relative displacement of the electrodes.
Furthermore, the elastic contacts on the upper surface of the interposer may be elastically biased against the electrodes of the electronic component disposed above the interposer or against electrodes provided in the at least one electronic component disposed above the interposer, and the elastic contacts on the lower surface of the interposer may be elastically biased against the pattern electrodes of the base substrate or against the electrodes of the electronic component disposed below the interposer.
Furthermore, the electronic component and the interposer are preferably fixed to each other with a first thermosetting or thermoplastic adhesive member disposed therebetween, and the interposer and the base substrate are preferably fixed to each other with a second thermosetting or thermoplastic adhesive member disposed therebetween.
Accordingly, this ensures the connection between the electrodes and the elastic contacts.
For example, the elastic contacts include spiral contact members or stressed metal members.
A lower surface of the base substrate may be provided with an external connection electrode.
According to another aspect of the present invention, a method for manufacturing a semiconductor device includes a first step for stacking at least two electronic components above a base substrate so as to form layers while mounting interposers and thermosetting or thermoplastic adhesive members between the adjacent layers, the at least two electronic components being provided with electrodes and the base substrate being provided with pattern electrodes, each interposer having opposite surfaces provided with a plurality of elastic contact's, the pattern electrodes and the electrodes being temporarily electrically connected via the elastic contacts, the electrodes being temporarily electrically connected to each other via the elastic contacts; a second step for implementing a matching inspection between the at least two electronic components by receiving an electric signal from an external source; and a third step for heating the adhesive members so as to fixedly bond the at least two electronic components together and/or fixedly bond the at least two electronic components to the base substrate.
Furthermore, if the matching between the at least two electronic components is determined to be defective in the second step, one of the at least two electronic components is preferably replaced with a new electronic component before repeating the first step.
According to the present invention, even in a case where the positional relationship between the elastic contacts and the electrodes is subject to relative displacement caused by a difference in coefficient of thermal expansion, the elastic contacts can be slid against the electrodes so as to be continuously elastically biased against the electrodes. Accordingly, this prevents separation or cracking in the electrode connection areas, whereby the electrical connection between the elastic contacts and the electrodes can be properly maintained.
Furthermore, since the matching inspection is incorporated into the manufacturing process, a combination of mismatched electronic components is prevented before the electronic components are fixedly bonded to each other. Accordingly, this contributes to a higher yield rate of the semiconductor device, which is the end product.
The semiconductor device 10 shown in
Referring to
The electronic components 12, 13, 14, 15 may alternatively be, for example, a Chip Scale Package (CSP) having substantially the same dimension as the bare chips. The electronic components 12, 13, 14, 15 are surrounded and sealed by a sealing material (mold resin) 18.
The base substrate 11 has a multilayer structure in which insulating layers composed of, for example, glass epoxy or polyimide and conductor layers are alternately stacked one on top of the other. The upper surface (top surface) of the base substrate 11 has a plurality of pattern electrodes 11a exposed thereon. The lower surface (bottom surface) of the base substrate 11 has external connection electrodes 17 arranged substantially in a matrix, such as a Ball Grid Array (BGA). The pattern electrodes 11a are electrically connected to the external connection electrodes 17 via the conductor layers in the multilayer base substrate 11. The base substrate 11 is rewired such that a pitch between the adjacent external connection electrodes 17 on the lower surface of the base substrate 11 is larger than a pitch between the adjacent pattern electrodes 11a on the upper surface.
Referring to
Referring to
The first embodiment shown in
Referring to
The spiral contact members 31 may be formed by, for example, etching or plating. If an etching technique is applied, a thin plate-like copper film is etched into the shape shown in
On the other hand, if a plating technique is applied, the spiral contact members 31 may be formed with copper layers. Alternatively, the spiral contact members 31 may be formed by depositing copper and nickel layers on top of each other by continuous plating, or by depositing copper and nickel-phosphorous layers on top of each other by continuous plating.
Referring to
The adhesive members 25 may be formed of, for example, a thermosetting or thermoplastic adhesive film or adhesive paste, such as a non-conductive film (NCF) or a non-conductive paste (NCP). If the adhesive members 25 are formed of sheet-like adhesive films, each film is provided with a plurality of through holes that correspond to the plurality of spiral contact members 31 defining the elastic contacts 30.
Accordingly, each spiral contact member 31 is in a contracted state, such that the first end 35 serving as a contact is constantly elastically pressed against the corresponding electrode 16. For example, the electrodes 16 of the lower electronic component 12 and the electrodes 16 of the upper electronic component 13 respectively facing each other across the interposer 20B are electrically connected to each other via the spiral contact members 31 on the upper side of the interposer 20B, the spiral contact members 31 on the lower side of the interposer 20B, and the electric conductors 22 disposed between the upper and lower spiral contact members 31 of the interposer 20B.
As mentioned above, the bases 21, the electronic components 12, 13, 14, 15, and the base substrate 11 are composed of materials having the same or similar coefficient of thermal expansion. For example, in a case where the ambient temperature surrounding the semiconductor device 10 changes and thus induces deformation of the electronic components 12, 13, 14, 15, the interposers 20, and the base substrate 11, the positional relationship between the pattern electrodes 11a and the spiral contact members 31 and between the electrodes 16 and the spiral contact members 31 may be subject to relative displacement, as shown in
The positional relationship mentioned above applies similarly to the relationship among the base substrate 11, the interposer 20A, and the electronic component 12.
A second embodiment of the present invention will now be described with reference to
The second embodiment shown in
Each of the stressed metal members 40 includes a bent conductive contact strip 41. The contact strip 41 has a stationary portion 41a and an elastically deformable portion 41b. One of the surfaces of the stationary portion 41a is provided with a sacrificial layer 42. The sacrificial layer 42 may either be conductive or insulative. For example, the sacrificial layer 42 may be, for example, a resin layer mixed with Ti or conductive filler.
The contact strip 41 is coated with a conductive metal film (not shown) of, for example, Au. The metal film is formed by, for example, plating. A section of the metal film on the stationary portion 41a functions as a bonding layer to the corresponding end surface of the electric conductor 22. For example, an undersurface (i.e. bonding surface) of the stationary portion 41a of the contact strip 41 is securely bonded to the corresponding end surface of the electric conductor 22 via the metal film by, for example, ultrasonic welding.
Referring to
The bending characteristic of the elastically deformable portion 41b is achieved by giving different internal stresses to different internal sections of the elastically deformable portion 41b in a predetermined manufacturing step. In detail, for a stressed metal member 40A provided on the upper side of each interposer 20, one surface (upper surface) of the elastically deformable portion 41b is given a compressive stress, whereas the other surface (lower surface) is given a tensile stress. On the other hand, for a stressed metal member 40B provided on the lower side of each interposer 20, one surface (lower surface) of the elastically deformable portion 41b is given a compressive stress, whereas the other surface (upper surface) is given a tensile stress.
Accordingly, the elastically deformable portion 41b of the upper stressed metal member 40A is bent upward in
Referring to
As the adhesive members 25 harden, the distance between the base substrate 11 and the interposer 20A and the distance between the interposer 20A and the electronic component 12 become smaller in comparison to the non-hardened state of the adhesive members 25. For this reason, each of the electrodes 16 of the upper electronic component 13 applies pressure to the free end (first end) of the corresponding stressed metal member 40A in the direction of the arrow Z2, thus allowing the stressed metal member 40A to be elastically deformed downward. Similarly, each of the electrodes 16 of the lower electronic component 12 applies pressure to the free end (first end) of the corresponding stressed metal member 40B in the direction of the arrow Z1, thus allowing the stressed metal member 40B to be elastically deformed upward.
Accordingly, the electrodes 16 of the upper electronic component 13 and the electrodes 16 of the lower electronic component 12 are electrically connected to each other via the stressed metal members 40A, the electric conductors 22, and the stressed metal members 40B.
In the second embodiment, the free ends (first ends) of the stressed metal members 40A and the stressed metal members 40B are constantly elastically biased against the respective electrodes 16, 16. Therefore, even in a case where deformation of the electronic components 12, 13, 14, 15, the interposers 20, and the base substrate 11 caused by a change in ambient temperature induces relative displacement in the positional relationship between the stressed metal members 40 and the electrodes 16, the free ends (first ends) of the stressed metal members 40 can be slid against the displaced electrodes 16 so as to be continuously elastically biased against the electrodes 16. Thus, the electrical connection between the electrodes 16 of the lower electronic component 12 and the electrodes 16 of the upper electronic component 13 can constantly be maintained. Accordingly, the stressed metal members 40 compensate for the displacement caused by a difference in coefficient of thermal expansion, thereby preventing defective electrical continuity caused by separation or cracking in the electrode connection areas. The positional relationship mentioned above applies similarly to the relationship among the base substrate 11, the interposer 20A, and the electronic component 12.
A method for manufacturing and inspecting the semiconductor device 10 equipped with the elastic contacts 30 described above will now be described with reference to
In step S1, a set of electronic components 12, 13, 14, 15 and the interposers 20A, 20B, 20C, 20D constituting the semiconductor device 10 subject to inspection are stacked alternately in a predetermined order on the base substrate 11. In this step, the adhesive members 25 in a non-hardened state are respectively provided at predetermined positions between the interposers 20A, 20B, 20C, 20D and the electronic components 12, 13, 14, 15 and between the interposer 20A and the base substrate 11.
In
The temporal securing of the components mentioned above can be readily achieved using a designated maintaining member, such as a socket.
In step S2, the plurality of external connection electrodes 17 provided on the lower surface of the base substrate 11 is supplied with power and electric signals from an external source so as to implement a matching inspection among the set of electronic components 12, 13, 14, 15 included in the semiconductor device 10. The matching inspection may include, for example, continuity checking, an impedance matching inspection, an on-resistance measurement inspection between terminals, and a leakage-current inspection.
In step S3, the semiconductor device 10 that has passed the inspection is heated at a predetermined temperature for a predetermined time period. Then, the adhesive members 25 harden so that the base substrate 11 and the interposer 20A become fixedly bonded to each other and the electronic components 12, 13, 14, 15 and the interposers 20B, 20C, 20D also become fixedly bonded to each other. Due to thermal contraction of the adhesive members 25, the elastic contacts 30 contract accordingly, whereby the electrical connection between the first ends of the elastic contacts 30 and the electrodes 16 and the electrical connection between the first ends of the elastic contacts 30 and the pattern electrodes 11a are maintained.
In a case where the adhesive members 25 are formed of a thermoplastic adhesive material, each adhesive member 25 thermally contracts as it cools down from the heated state to room temperature. Thus, the distance between the base substrate 11 and the interposer 20A and the distance between the interposers 20 and the electronic components 12, 13, 14, 15 become smaller. Accordingly, this achieves a good connection state in which the electrodes 16 of the electronic components 12, 13, 14, 15 are constantly in contact with the corresponding elastic contacts 30.
In step S4, the semiconductor device 10 is entirely sealed with the sealing material 18 by resin molding so that an end product is attained. Since the semiconductor device 10 manufactured by this method has passed the matching inspection, the semiconductor device 10 can be shipped as a Known Good Die (KGD) product.
On the other hand, if the semiconductor device 10 fails the inspection in step S2, the operation returns to step S1 where, for example, the electronic component 15 of the set of electronic components 12, 13, 14, 15 is replaced with a new electronic component 15. Subsequently, the operation proceeds to step S2 where the matching inspection is implemented again.
If the semiconductor device 10 having the new set of electronic components 12, 13, 14, 15 passes the re-inspection, the electronic components 12, 13, 14, 15 are fixedly bonded to the interposers 20A, 20B, 20C, 20D and the base substrate 11 with the adhesive members 25 in step S3. Subsequently, the resin molding process is performed on the semiconductor device 10 in step S4. Since it is highly probable that the old electronic component 15 replaced with the new one is defective, the electronic component 15 may be discarded or may be subject to a more detailed inspection.
On the other hand, if the semiconductor device 10 fails the re-inspection step, it is highly probable that at least one of the electronic components 12, 13, and 14 is defective. In that case, for example, the electronic component 14 is replaced with a new one, and the same re inspection step is implemented again on the semiconductor device 10 with the new set of electronic components. If the semiconductor device 10 passes the re-inspection, the thermal-fixing process is performed on the semiconductor device 10 in step S3. Subsequently, the resin-molding process is performed on the semiconductor device 10 in step S4.
In the method for manufacturing the semiconductor device 10 according to the present invention, the matching inspection of the electronic components 12, 13, 14, 15 can be implemented in the assembled state thereof. Accordingly, this preliminarily prevents a combination of mismatched electronic components, thereby contributing to a higher yield rate of the semiconductor device 10 (i.e. the percentage of products manufactured in a manufacturing line from which defective products are subtracted).
Furthermore, even if a combination of electronic components is determined to be defective the first time, there is still a possibility that the combination of electronic components having at least one of the electronic components replaced with a new one may be determined to be non-defective in a re-inspection process. Therefore, only the electronic components that are determined to be defective in the final inspection may be discarded. Accordingly, this reduces the number of electronic components to be discarded, thereby contributing to a higher yield rate of the electronic components.
Although the spiral contact members 31 and the stressed metal members 40 are used as the elastic contacts 30 in the above embodiments, the present invention may include other alternatives for the elastic contacts 30. For example, such alternatives may include a membrane-type elastic contact having a metal film that forms a top layer and an elastic body composed of rubber or elastomer attached to a bottom surface of the metal film, an elastically deformable spring pin (contact pin) whose first end serving as a contact is bent into a substantially U-shape, a contact probe (see Japanese Unexamined Patent Application Publication No. 2002-357622), and a volute spring.
Number | Date | Country | Kind |
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2005-145243 | May 2005 | JP | national |