This invention relates to a semiconductor device, and in particular to a semiconductor device and a manufacturing method thereof realized by directly mounting a semiconductor chip to a substrate by using projecting connection terminals (electrodes) which are arranged on one surface of a planar semiconductor chip.
The development of smaller, highly sophisticated consumer electronics has increased demands for compact and low-profiled semiconductor chips used in consumer electronic devices correspondingly. To accommodate this increase in demand, a connection method to connect a semiconductor chip and the substrate in the semiconductor device has been developed which is referred to as flip chip bonding. In traditional wire bonding techniques, the chip and the substrate are connected by wires, with a surface of the chip facing upwards, upon which connection terminals are provided. With flip chip bonding, protruding connection terminals referred to as “bumps” are provided on the chip. The chip is reversed (flipped) so that the bumps are on the lower surface and are thus directly connected to the substrate.
With flip chip bonding, the area at the bump periphery between the chip and the substrate is filled with a thermo-setting resin referred to as “underfill” for reinforcement. However, mounting using flip chip bonding poses a problem that this underfill material would often crawl up. This is depicted with reference to
When mounting chip 1 onto the substrate 3, an underfill 4 is coated in advance at locations where chip 1 is to be fixed to the substrate 3, for instance. Chip 1 is picked up by a bonding head 5 and is mounted at the fixing location of chip 1 on the substrate 3 onto which the underfill 4 is coated. Then, pressure and heat are applied from above by the bonding head 5. As a result, the underfill 4—which is typically a thermo-setting resin—cures, thereby fixing the chip 1 to substrate 3.
If the coated amount of underfill 4 is small, there is a risk that the underfill 4 will not sufficiently reach the periphery of bumps 2. This means that the underfill 4 must be coated in larger amounts to a certain degree. On the other hand, if the underfill 4 is coated in large amounts, the excess underfill 4 sticks out at the periphery of chip 1. The part of underfill 4 that sticks out is referred to as a “fillet portion.” If the volume of the fillet portion is large, the underfill 4 may rise and coat the side surface(s) of chip 1 as shown in
If the underfill 4 adheres to the bonding head 5, the chip 1 may be lifted to some degree, thereby causing shearing to occur in bumps 2 when the bonding head 5 is pulled up after mounting is completed. Furthermore, the underfill 4 that adhered cures and damages the flatness of the bonding head 5, thereby causing a drop in the quality of flip chip products.
However, in conventional techniques for preventing the rise and coating of the underfill 4, the peripheral edge of the front surface 11 of chip 1 is removed to provide a ledge at the periphery of the front surface 11. This ledge prevents the underfill 4 from rising up and coating the side surface of the chip 1.
However, the fillet portion of the underfill 4 may exceed the ledge formed at the periphery of the front surface 11 of chip 1. The ledge formed at the periphery of the front surface 11 of chip 1 may therefore be insufficient with respect to the volume of the fillet portion, thereby creating a problem that coating of the side surfaces of the chip 1 cannot be prevented.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
The semiconductor device according to the present invention has a planar semiconductor chip having protruding connection terminals provided on one surface thereof. The semiconductor chip also has a shelf provided where a peripheral edge is removed on a surface thereof opposite the surface having connection terminals provided thereon.
A fillet portion of underfill with a larger volume can thus be managed, thereby enhancing the function of preventing underfill crawl up by providing a shelf in the semiconductor chip.
According to one embodiment, a semiconductor device is manufactured having a planar semiconductor chip with projecting connection terminals provided on one surface thereof. A wafer is diced from a surface opposite the surface onto which a plurality of circuits is formed, thus forming individual chips from the wafer.
As a result, a shelf is provided where the peripheral edge is removed from a surface opposite the one surface of the semiconductor chip onto which connection terminals are provided. This enables manufacturing in which problems caused by the underfill crawling up are more reliably prevented when mounting using flip chip bonding.
According to the semiconductor device and the manufacturing method thereof according to embodiments of the present invention, problems caused by the underfill coating the side surfaces of a chip can be more reliably prevented when mounting using flip chip bonding.
The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention;
a is a graphical depiction of a first state in a conventional flip chip bonding technique;
b is a graphical depiction of a second state in a conventional flip chip bonding technique;
c is a graphical depiction of a third state in a conventional flip chip bonding technique;
d is a graphical depiction of a fourth state in a conventional flip chip bonding technique;
e is a graphical depiction of a potential fifth state in a conventional flip chip bonding technique;
f is a graphical depiction of a potential fifth state in a conventional flip chip bonding technique;
a is a graphical depiction of a first state in a method for flip chip bonding in accordance with various embodiments;
b is a graphical depiction of a second state in a method for flip chip bonding in accordance with various embodiments;
c is a graphical depiction of a third state in a method for flip chip bonding in accordance with various embodiments e;
d is a graphical depiction of a fourth state in a method for flip chip bonding in accordance with various embodiments;
e is a graphical depiction of a potential fifth state in a method for flip chip bonding in accordance with various embodiments;
f is a graphical depiction of a potential fifth state in a method for flip chip bonding in accordance with various embodiments;
Reference will now be made in detail to several embodiments. While the subject matter will be described in conjunction with the alternative embodiments, it will be understood that they are not intended to limit the claimed subject matter to these embodiments. On the contrary, the claimed subject matter is intended to cover alternative, modifications, and equivalents, which may be included within the spirit and scope of the claimed subject matter as defined by the appended claims.
Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the claimed subject matter. However, it will be recognized by one skilled in the art that embodiments may be practiced without these specific details or with equivalents thereof. In other instances, well-known processes, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects and features of the subject matter.
With reference now to
As shown in
The function of preventing the rising of underfill 4 by providing a shelf in chip 1 in the present invention is compared to the same function in the reference, and a description will be given on the effects of providing the shelf on the back surface of chip 1, according to the present invention, by referring to
As shown in
The estimated results of
Next, the volume of each portion of the underfill 4 is calculated from the cross-section area. With the front surface double cut, the volume of the die lower portion 41 of underfill 4 is determined by multiplying its cross section area (a) by the length obtained by subtracting the double cut shelf on both sides, in other words, 30 [μm]×2=60 [μm] from the 10 [mm] which is the die size. Accordingly, the relevant volume becomes approximately 2.5 [mm3] (e). With the back surface double cut, the volume of the die lower portion 41 of the underfill 4 is obtained by multiplying its cross section area (c) by the die size 10 [mm]. Accordingly, the relevant volume becomes 2.5 [mm3] (g). With the front surface double cut and the back surface double cut, the volume of the fillet portion 42 of the underfill 4 is calculated by multiplying the relevant cross sectional area (b, d) by the length of four sides of chip 1, in other words, the die size 10 [mm]×4=40 [mm]. With the front surface double cut, the relevant volume becomes 0.28 [mm3] (f) and with the back surface double cut, the relevant volume becomes 0.52 [mm3] (h).
The overall volume of the underfill 4 is calculated from the volume of each portion of underfill 4. The overall volume of the underfill 4 is determined by adding up the volumes (e, g) of the die lower portion 41 of the underfill 4 and the volumes (f, h) of the fillet portion 42. Accordingly, with the front surface double cut, the volume is 2.78 [mm3] (i) and with the back surface double cut, the volume is 3.02 [mm3] (j).
The fillet portion volume ratio which represents the ratio of the volume of the fillet portion 42 to the overall volume of underfill 4 is obtained by dividing the volume (f, h) of the fillet portion 42 by the overall volume (i, j) of 30 the underfill 4. Accordingly, with the front surface double cut, the ratio is approximately 10.0[%] (k), and with the back surface double cut, the ratio is approximately 17.2[%] (1).
The fillet portion volume ratios determined for the front surface double cut and the back surface double cut as was described are then compared. As can be noted, in any of the 100 μm die, the 200 μm die, the 300 μm die and the 400 μm die, the filet portion volume ratio for the back surface double cut is higher than that for the front surface double cut. Specifically, the ratio of the volume of the fillet portion 42 to the overall volume of the underfill 4 is high. When the rate of the volume of fillet portion 42 in the state that the underfill 4 starts rising up the side surface of chip 1 is high, this indicates that the amount of underfill 4 that may stick out at the periphery of chip 1 is large. Accordingly, as compared to the front surface double cut, with the back surface double cut according to the present invention, an improvement can be noted in the function of preventing the rising and coating of the underfill 4 by providing a shelf in chip 1.
The chips diced from the back surface of the wafer as described above are flip-chip connected in a die bonding process in the next step. As a result of forming chips by dicing the wafer from its back surface, a shelf is provided where the peripheral edge of the surface opposite one surface of the semiconductor chip onto which connection terminals are provided is removed. Thus, mounting using flip chip bonding enables manufacturing which can more reliably prevent problems caused by the underfill coating the side surfaces of the chip.
A detailed description will now be given on the step of imprinting a laser mark on the back surface of the wafer (S6), from amongst the respective steps of the flow shown in
The dummy wafer 6 has a through hole formed therein to allow confirmation. The dummy wafer 6 has its front surface facing downwards and its back surface facing upwards. The upper camera 71 serves to confirm the laser mark imprinted on the wafer. The lower camera 72 serves to recognize the circuit pattern on the surface of the wafer. The axis of the upper camera 71 with the lower camera 72 is detected using the dummy wafer 6. This detection includes numerical position correction. Next, the center positions of the upper camera 71 and the laser irradiator 8 are corrected. The laser 81 in the laser irradiator 8 makes an imprint at a specified position of the dummy wafer 6. The distance between the center positions of the upper camera 71 and the laser irradiator 8 is measured by confirming the imprinted laser mark using the upper camera 71, and is then corrected. The wafer is conveyed by the KY robot table 9.
Correction of the center positions of the upper camera 71 and the laser irradiator 8 includes correction of the convey errors caused by the XY robot table 9. The running test of the device is carried out using the dummy wafer 6 as described. As a result, using the upper camera 71, the lower camera 72 and the shift amount of the KY robot table 9, the circuit pattern on the front surface of the wafer is recognized, thereby allowing imprint of the laser mark at a random position of the back surface of the wafer. The wafer can be diced from its back surface by referencing the imprinted laser mark.
As was described in detail in the above text, according to the embodiment directed to the present invention, the wafer is diced from the back surface (surface opposite the circuit forming surface) to form individual chips from the wafer. As a result, a shelf is formed where the peripheral edge of the surface opposite the one surface of the semiconductor chip onto which connection terminals are formed is removed. Accordingly, a larger volume of the fillet portion of the underfill can be secured thereby improving the function of preventing rising up of the underfill by providing the shelf in the semiconductor chip.
In contrast to conventional techniques wherein the width of the double cut shelf cannot be made larger than the area which has no influence on the circuit pattern because the wafer is diced from its front surface (circuit forming surface). However, in the present invention, this constraint does not exist because the wafer is diced from its back surface.
Also, since the wafer is diced from its back surface in the present invention, the dicing tape which is conventionally attached to the back surface of the wafer is attached to the front surface of the wafer (refer to
The present invention is not limited to the embodiment described above, but needless to say, various improvements and modifications can be made thereto without departing from the scope of the present invention. For instance, the values of the die thickness, the double cut shelf, etc. are simply one example, and needless to say the invention is not limited to these values. The double cut shelf is sufficient as long as the fillet portion 42 does not touch the bonding head 5.
Although
In the present embodiment, the chip 1 is connected to the substrate 3, but this is not limited to this connection pattern. The chip 1 may also be connected with the package carrier such as a lead frame, etc., for instance, in addition to the substrate. The invention can also be applied to chip-on-chip mounting connecting the chips.
In the present embodiment, since the wafer is diced from the back surface, the position of the wafer is identified by referencing the laser mark imprinted on the back surface of the wafer as shown in
While the following exemplary configurations are shown as incorporating specific, enumerated features and elements, it is understood that such depiction is exemplary. Accordingly, embodiments are well suited to applications involving different, additional, or fewer elements, features, or arrangements.
Number | Date | Country | Kind |
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2007339935 | Dec 2007 | JP | national |
This application is a divisional of U.S. patent application Ser. No. 12/343,348, filed Dec. 23, 2008 which claims priority from Japanese patent application 2007-339935 filed on Dec. 28, 2007. Each of these references is incorporated herein by reference in their entireties and for all purposes.
Number | Date | Country | |
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Parent | 12343348 | Dec 2008 | US |
Child | 13918674 | US |