Abstract
A large scale integrated circuit chip includes a semiconductor circuit having a multilayered wiring structure, a metal guard ring surrounding the semiconductor circuit, and a plurality of external connection terminals, on a semiconductor circuit. The plurality of external connection terminals connect to an uppermost-layer wiring of the multilayered wiring structure and are exposed on a surface of the large scale integrated circuit chip. A predetermined external connection terminal conducts to a predetermined wiring through a conductive via within the guard ring and conducts to a conductive piece through another conductive via outside the guard ring. One side of the external connection terminal extending over the guard ring connects to the conductive piece, and the other side of the external connection terminal connects to the uppermost-layer wiring within the guard ring. Thus, a cutout part is not necessary in the guard ring.
Claims
1. A large scale integrated circuit chip comprising: a semiconductor substrate; a semiconductor circuit formed above the semiconductor substrate and having a vertically multilayered wiring structure; a metal guard ring formed above the semiconductor substrate and surrounding the semiconductor circuit; and a plurality of external connection terminals connecting to a predetermined wiring of the multilayered wiring structure of the semiconductor circuit and exposed on a surface of the large scale integrated circuit chip, wherein a predetermined external connection terminal among the plurality of external connection terminals conducts to the predetermined wiring through a conductive via within the guard ring and conducts to a conductive piece through another conductive via outside the guard ring, and wherein the conductive piece is a piece of a test lead-out wiring and is a wiring having a cut surface that is exposed by dicing.
2. The large scale integrated circuit chip according to claim 1, wherein the external connection terminals are made of a noble metal wiring material, and the conductive piece and the guard ring are made of an aluminum wiring material.
3. The large scale integrated circuit chip according to claim 2, wherein the conductive piece enters into an indent part that inwardly indents from the outside to an inside of the guard ring and connects to the predetermined external connection terminal through the other conductive via at a position overlapping the predetermined external connection terminal in a vertical direction.
4. The large scale integrated circuit chip according to claim 2, wherein the conductive piece is a wiring that extends from a test pad formed in a dicing region having been subjected to dicing.
5. The large scale integrated circuit chip according to claim 2, wherein the guard ring is formed of closed-circuit wirings and conductive circumferential vias, wherein the closed-circuit wirings form closed circuits and are arranged at respective wiring layers of the multilayered wiring structure overlappingly in a vertical direction so as to surround an outside of the semiconductor circuit, and wherein the circumferential vias vertically and mutually connect the closed-circuit wirings of the wiring layers, which are adjacent to each other in the vertical direction.
6. A large scale integrated circuit wafer comprising: a semiconductor wafer; a plurality of chip forming regions arranged on the semiconductor wafer so as to be mutually separated, wherein each of the chip forming regions includes a semiconductor circuit, a metal guard ring, and a plurality of external connection terminals, wherein the semiconductor circuit is formed above the semiconductor wafer and has a vertically multilayered wiring structure, and wherein the metal guard ring is formed above the semiconductor wafer and surrounds the semiconductor circuit, and wherein the plurality of external connection terminals connect to a predetermined wiring of the multilayered wiring structure of the semiconductor circuit and are exposed on a surface of the large scale integrated circuit wafer; dicing regions formed between the plurality of chip forming regions, wherein the dicing regions have a plurality of test pads; and a plurality of predetermined external connection terminals among the plurality of external connection terminals in the chip forming regions that have the same function, wherein each of the predetermined external connection terminals conducts to the predetermined wiring through a conductive via within the guard ring and connects to a test lead-out wiring, which is drawn out from the test pad, through another conductive via outside the guard ring.
7. The large scale integrated circuit wafer according to claim 6, wherein the external connection terminals are made of a noble metal wiring material, and the conductive pieces and the guard rings are made of an aluminum wiring material.
8. The large scale integrated circuit wafer according to claim 7, wherein: the predetermined external connection terminals having the same function conduct to each other in the corresponding chip forming region; at least three chip forming regions are arranged along one direction so that the dicing region is interposed between the chip forming regions on the semiconductor wafer; and the test lead-out wiring is drawn out from the test pad, wherein the test pad is formed in the dicing region, toward the chip forming region at each side of the dicing region, and wherein the test pad connects to one of the predetermined external connection terminals, which are formed in the chip forming region at each side of the dicing region and have the same function.
9. The large scale integrated circuit wafer according to claim 8, wherein the predetermined external connection terminals are power source terminals or ground terminals.
10. The large scale integrated circuit wafer according to claim 7, wherein each of the test lead-out wirings enters into an indent part that inwardly indents from the outside to an inside of the guard ring and connects to the predetermined external connection terminal through the conductive via at a position overlapping the predetermined external connection terminal in a vertical direction.
11. The large scale integrated circuit wafer according to claim 7, wherein the guard ring is formed of closed-circuit wirings and conductive circumferential vias, wherein the closed-circuit wirings form closed circuits and are arranged at respective wiring layers of the multilayered wiring structure overlappingly in a vertical direction so as to surround an outside of the semiconductor circuit, and wherein the circumferential vias vertically and mutually connect the closed-circuit wirings of the wiring layers, which are adjacent to each other in the vertical direction.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] FIG. 1 is a plan view showing an uppermost-layer wiring within a guard ring and a test lead-out wiring outside the guard ring, which are separated by the guard ring.
[0048] FIG. 2 is a sectional view taken along a line A1-A1 in FIG. 1.
[0049] FIG. 3 is a plan view showing the test lead-out wiring that is exposed at a side surface of a chip by dicing from the condition shown in FIG. 1.
[0050] FIG. 4 is a sectional view taken along a line A2-A2 in FIG. 3.
[0051] FIG. 5 is a plan view schematically showing a part of a large scale integrated circuit wafer.
[0052] FIG. 6 is a perspective view showing an example of a structure of the guard ring.
[0053] FIG. 7 is a sectional view taken along a CDEF plane in FIG. 6.
[0054] FIG. 8 is a vertical sectional view showing a part of the large scale integrated circuit wafer before a gold bump is formed.
[0055] FIG. 9 is a vertical sectional view showing the part of the large scale integrated circuit wafer of which surface is sputtered to form a UBM in the condition shown in FIG. 8.
[0056] FIG. 10 is a vertical sectional view showing the part of the large scale integrated circuit wafer of which surface is coated with a photoresist in the condition shown in FIG. 9.
[0057] FIG. 11 is a vertical sectional view showing an exposure step performed on the part of the large scale integrated circuit wafer in the condition shown in FIG. 10.
[0058] FIG. 12 is a vertical sectional view showing the part of the large scale integrated circuit wafer that is developed in the condition shown in FIG. 11.
[0059] FIG. 13 is a vertical sectional view showing the part of the large scale integrated circuit wafer that is plated with gold in the condition shown in FIG. 12.
[0060] FIG. 14 is a vertical sectional view showing the part of the large scale integrated circuit wafer from which the photoresist is removed in the condition shown in FIG. 13.
[0061] FIG. 15 is a vertical sectional view showing the part of the large scale integrated circuit wafer from which the UBM is removed in the condition shown in FIG. 14.
[0062] FIG. 16 is a plan view showing a comparative example in which a test lead-out wiring outside a guard ring connects to an uppermost-layer wiring within the guard ring through a cutout part of the guard ring.
[0063] FIG. 17 is a sectional view taken along a line B1-B1 in FIG. 16.
[0064] FIG. 18 is a plan view showing the test lead-out wiring that is exposed at a side surface of a chip by dicing from the condition shown in FIG. 16.
[0065] FIG. 19 is a sectional view taken along a line B2-B2 in FIG. 18.
DETAILED DESCRIPTION
[0066] FIG. 5 shows a part of a large scale integrated circuit wafer 9 according to an embodiment. As shown in FIG. 5, the large scale integrated circuit wafer 9 includes a semiconductor wafer 7 on which a plurality of chip forming regions 1w are arranged in matrix so as to be separated from each other. Dicing regions 8 are formed between the chip forming regions 1w. The chip forming regions 1w are subjected to dicing after the large scale integrated circuit wafer 9 is inspected to thereby obtain large scale integrated circuit chips 1. The semiconductor wafer 7 is formed in a circular shape in practical use and is made of single crystal silicon, for example. As shown in FIG. 6, the semiconductor wafer 7 is also called a semiconductor substrate 10 in the large scale integrated circuit chip 1. The usage of the chip forming regions 1w is not limited to a specific object. Here, the chip forming regions 1w are made as display driver ICs for driving liquid crystal panel displays. Each of the chip forming regions 1w has a long shape, and a great number of external connection terminals 16_1 to 16_m and 17_1 to 17_n are arranged along the long sides of the respective chip forming regions. The external connection terminals 17_1 to 17_n, which are arranged along one of the long sides of the chip forming region 1w, may be respectively used as a source driving terminal, a gate control signal terminal, a display synchronizing signal terminal, a power source terminal, and a ground terminal for a liquid crystal panel. The external connection terminals 16_1 to 16_m, which are arranged along the other long side of the chip forming region 1w, may be used as terminals for a host interface.
[0067] Each of the chip forming regions 1w includes a semiconductor circuit 11 and a metal guard ring 14, as shown in FIG. 6. The semiconductor circuit 11 has desired circuit elements, such as a MOS transistor and a capacitive element, and a vertically multilayered wiring structure above the semiconductor wafer 7. The guard ring 14 is also formed above the semiconductor wafer 7 and surrounds the semiconductor circuit 11.
[0068] Circuit elements are formed on a main surface of the semiconductor wafer 7 and are connected to multilayered wirings as desired, and thus, the semiconductor circuit 11 has a necessary circuit function, for example, a display controlling function that is necessary for the display driver IC. Although not limited to a specific structure, the multilayered wiring structure may be a five-layered wiring structure in which wiring layers L1 to L5 are stacked above the circuit elements. In this case, each of the wiring layers has a desired wiring pattern for constituting wiring to connect the circuit elements. The wiring of each of the wiring layers is, for example, aluminum wiring, and is insulated by an interlayer insulating film. A publicly known production technology for a CMOS integrated circuit can be applied to the device structure and the production method for the circuit elements and the wiring layers L1 to L5 in the semiconductor circuit 11, and therefore, detailed description thereof will be omitted.
[0069] The guard ring 14 is formed of closed-circuit wirings 12_1 to 12_6 and conductive circumferential vias 13_1 to 13_5, as shown in FIG. 6. The closed-circuit wirings 12_1 to 12_6 form closed circuits and are arranged at the respective wiring layers L1 to L5 of the multilayered wiring structure overlappingly in a vertical direction so as to surround an outside of the semiconductor circuit 11. The circumferential vias 13_1 to 13_5 vertically and mutually connect the closed-circuit wirings 12_1 to 12_6 of the wiring layers, which are adjacent to each other in the vertical direction. The guard ring 14 forms a wall that surrounds the semiconductor circuit 11. The closed-circuit wirings 12_1 to 12_6 are made of, for example, the same aluminum wiring material as that of the other wirings. The circumferential vias 13_1 to 13_5 are made of, for example, the same aluminum wiring material as that of the other vias. The guard ring 14 has a vertical sectional structure as shown in FIG. 7, and FIG. 7 is a sectional view taken along a CDEF plane in FIG. 6. The guard ring 14 can be produced by a publicly known production method, such as one disclosed in JP-A-2012-89668.
[0070] The dicing regions 8 have a plurality of test pads 4, as exemplified in FIG. 5. The positions of the test pads 4 are not limited to specific positions, but the test pads 4 may be arranged in the dicing regions 8 that are adjacent to short sides of the chip forming regions 1w. Each of the test pads 4 has a test lead-out wiring 6 at each side, and the test lead-out wirings 6 extend to the chip forming regions 1w. The test lead-out wirings 6 can connect to any terminals. For example, one of the test lead-out wirings 6 at both sides of the test pad 4 connects to the external connection terminal 17_1 in the chip forming region 1w on the right side in FIG. 5, and the other test lead-out wiring 6 connects to the external connection terminal 17_n in the chip forming region 1w on the left side in FIG. 5. The external connection terminals 17_1 and 17_n in the chip forming region 1w are conducted by a power source wiring Lvdd or a ground wiring Lvss within the chip forming region 1w. Thus, as clearly shown in FIG. 5, the plurality of chip forming regions that are arranged in a line in the lateral direction are supplied with power source or are grounded through one of the test pads 4 that are arranged in the same line. It is not necessary to supply power source or ground connection to each of the chip forming regions 1w through the respective test pads 4. That is, the test pads 4 are useful for collectively inspecting the semiconductor circuits 11 in the plurality of chip forming regions 1w.
[0071] One embodiment has a feature in the structure in which the test pad 4 is connected to the predetermined external connection terminal 17_1 without cutting apart of the guard ring 14. The structure of the connecting part therebetween in a plan view is shown in FIG. 1, and a cross section taken along a line A1-A1 in FIG. 1 is shown in FIG. 2. As shown in FIGS. 1 and 2, the external connection terminal 17_1 conducts to a predetermined uppermost-layer wiring 15 through a conductive via 18 within the guard ring 14 and also conducts to the test lead-out wiring 6, which is drawn out from the test pad 4, through a conductive via 19 outside the guard ring 14. Each of the predetermined uppermost-layer wiring 15, the test pad 4, and the test lead-out wiring 6 is formed on an uppermost wiring layer by using an aluminum wiring material, for example. The conductive via 19 is positioned outside the guard ring 14 in a plan view. That is, the test lead-out wiring 6 connects to the external connection terminal 17_1 through the conductive via 19 at a position overlapping the external connection terminal 17_1 in the vertical direction such that the test lead-out wiring 6 enters into an indent part 14A, which inwardly indents from the outside to the inside of the guard ring 14. The left side from a cut line D shown in FIGS. 1 and 2 is cut off by dicing. Thus, the test lead-out wiring 6 is cut at an intermediate part thereof and is exposed at a side surface of the large scale integrated circuit chip 1. FIG. 3 shows the test lead-out wiring 6 that is exposed at the side surface of the chip by dicing from the condition shown in FIG. 1. FIG. 4 shows a cross section taken along a line A2-A2 in FIG. 3. It should be noted that a passivation film for covering the large scale integrated circuit wafer except for the test pad 4 and the external connection terminal 17 is not shown in FIGS. 1 and 3.
[0072] The external connection terminals 17 are made of a noble metal wiring material and are formed as gold bumps, for example. FIG. 8 shows an example of a part of the large scale integrated circuit wafer before the gold bump is formed. The uppermost-layer wiring 15 is formed as an aluminum pad. The reference numeral 21 denotes an aluminum wiring of a wiring layer L4. The reference numeral 20 denotes a barrier metal that is formed on upper and back surfaces of the aluminum wiring 21 and that is made of TiN, and the barrier metal 20 prevents deterioration due to corrosion of aluminum. The surface of the large scale integrated circuit wafer in the condition shown in FIG. 8 is sputtered with an under-bump metal (UBM) 23 (FIG. 9). Then, a photoresist 30 is coated on the UBM 23 (FIG. 10), and the surface of the photoresist 30 is exposed by using a photo mask 31 (FIG. 11). The photoresist 30 is developed after the exposure, whereby an opening 32 is formed at an unexposed part (FIG. 12). Next, gold plating is performed on the opening 32 by using the remaining photoresist 30 as a mask (FIG. 13). Then, the remaining photoresist 30 is removed (FIG. 14), and the exposed UBM 23 is removed (FIG. 15). Thus, the external connection terminal 17 is formed of a gold bump. The external connection terminal 17 formed of the gold bump has a thickness of 10 to 12 μm, and the wirings such as the uppermost-layer wiring 15 and the closed-circuit wirings 12_1 to 12_6 under the external connection terminal 17 have thicknesses of several thousands angstrom. As is clear from the above descriptions, the conductive vias 18 and 19 can also be formed in a partial step of producing the gold bump.
[0073] The large scale integrated circuit wafer 7 thus formed has a structure in which signals, power source, etc. can be commonly supplied from one of the test pads 4 to the plurality of chip forming regions 1w that are arranged in parallel. That is, the two predetermined external connection terminals 17_1 and 17_n having the same function conduct to each other in the corresponding chip forming region 1w, as exemplified in FIG. 5. Accordingly, signals or power source can be commonly supplied from one test pad 4 to the predetermined external connection terminals 17_1 and 17_n in the plurality of chip forming regions 1w, which are arranged in parallel so that the dicing regions 8 is interposed between each two of the chip forming regions 1w. Thus, the number of terminals of test probes, which are to be pushed against the test pads on a wafer before the wafer is diced, is reduced. In other words, increase in the number of the terminals of the test probes is avoided regardless of increase in the number of the external connection terminals in one chip forming region 1w. Moreover, conduction of the external connection terminals 17_1 and 17_n in the chip forming region 1w, as shown in FIG. 5, allows reduction in the number and the length of the test lead-out wirings that are to be arranged in the dicing regions.
[0074] Furthermore, the large scale integrated circuit wafer thus formed has a structure in which the uppermost-layer wiring 15 within the guard ring 14 is separated from the test lead-out wiring 6 outside the guard ring 14 by the guard ring 14. That is, one side of the external connection terminal 17_1, which extends over the guard ring 14, connects to the test lead-out wiring 6, and the other side of the external connection terminal 17_1 connects to the uppermost-layer wiring 15 within the guard ring 14. Thus, forming a cutout part at a part of the guard ring 14 is not necessary. Accordingly, the moisture-proof performance of the guard ring 14 is not degraded even though the conductive piece 6 of the test lead-out wiring extending to the inside of the semiconductor circuit 11 is exposed at a cut surface that is made by dicing or at another part in the large scale integrated circuit chip 1 having been subjected to dicing. As exemplified in FIG. 3, moisture and chlorine ions entering along the exposed conductive piece 6 are blocked off by the guard ring 14 and are prevented from entering within the guard ring 14. The conductive via 19 and the external connection terminal 17_1, which connect to the conductive piece 6, are formed of the gold bumps and are thereby not easily corroded. Thus, even when contamination develops to the conductive piece 6 at the outside of the guard ring, the conductive via 19 and the external connection terminal 17_1, which are made of the noble metal wiring material, are not greatly affected, and the moisture-proof performance is still maintained.
[0075] On the other hand, in a comparative example shown in FIGS. 16 and 17, a test lead-out wiring 42 outside a guard ring 43 connects through a cutout part 43A of the guard ring 43 to an uppermost-layer wiring 40 within the guard ring 43. In this case, moisture and chlorine ions entering along the conductive piece 42 that is exposed by dicing, enter within the guard ring 14 through the cutout part 43A, as shown in FIGS. 18 and 19. Thus, although the conductive via 18 and the external connection terminal 17_1 are formed of the gold bumps, contamination of the uppermost-layer wiring 40 underlying the conductive via 18 and the external connection terminal 17_1 can cause unstable conduction between the external connection terminal 17_1 and the uppermost-layer wiring 40, and the other parts can be damaged by corrosion that develops.
[0076] As exemplified in FIG. 1, the test lead-out wiring (conductive piece) 6 enters into the indent part 14A that inwardly indents from the outside to the inside of the guard ring 14. Thus, the conductive via 19 can be formed without the need for extending the external connection terminal 17_1 to the outside of the guard ring 14 in a plan view.
[0077] Although certain embodiments are specifically described above, the disclosure is not limited to these embodiments, and various changes and modifications can be made within the scope not departing from the gist of the disclosure.
[0078] For example, the test pad is arranged in the dicing region that faces the short side of the chip forming region with the long shape in the above descriptions, but the disclosure is not limited to this embodiment. That is, another embodiment comprises a test pad arranged in a dicing region that faces a long side of a chip forming region and connects to the inside of a guard ring in a chip forming region, and moreover, the disclosure can also be applied in a case of performing both of such embodiments. Additionally, the external connection terminal to which the disclosure is applied is not limited to one that is used for power source or ground and may be one that is used for any signals or any electric voltages, such as data, address, control signal, or reference voltage.
[0079] The noble metal wiring material is not limited to gold and may be platinum. The aluminum wiring material may be substituted with one of various kinds of wiring materials such as copper wiring materials and silicides. The number of the layers in the multilayered wiring structure is not limited to five and may be another number.
[0080] Additionally, the conductive vias 18 and 19 may not necessarily be made of noble metals and may be made by using an aluminum wiring material.
