Through silicon via (TSV) isolation structures for noise reduction in 3D integrated circuit

[0001] This application is a continuation of U.S. patent application Ser. No. 13/324,405, filed on Dec. 13, 2011, the contents of which are incorporated by reference as if set forth in their entirety.

[0002] The disclosure relates, most generally, to semiconductor devices and methods for manufacturing the same and the disclosure is more particularly directed to 3D integrated circuits, and structures and methods for noise isolation for through silicon vias.

[0003] 3D (three dimensional) integrated circuits have become very popular in recent years due to the increased levels of integration they provide. 3D integrated circuits utilize through silicon via (TSV) structures which are via openings that extend completely through a semiconductor substrate and enable devices above and below the substrate to be coupled to one another and to devices internal to the substrate and provide the interconnects compatible with 3D wafer level packaging. When filled, the TSV structures may serve as signal lines or other purposes. Signal lines can carry and create significant amounts of electrical noise that adversely affects semiconductor devices such as active transistors, in their vicinity.

[0004] It would therefore be desirable to take advantage of the advanced integration levels afforded by 3D integrated circuits using TSV structures while avoiding problems associated with electrical noise created by such TSV structures.

[0011] FIG. 1 is a cross-sectional view showing one exemplary aspect of the disclosure. FIG. 1 shows semiconductor substrate 2 which may be a P-type semiconductor substrate according to one exemplary embodiment and may be an N-type semiconductor substrate according to another exemplary embodiment. Semiconductor substrate 2 includes opposed surfaces including top surface 4 and opposed bottom surface 6. Semiconductor substrate 2 with bottom surface 6 is shown after a backgrinding or lapping process has been used to diminish the original thickness of semiconductor substrate 2 as will be shown in subsequent figures, for example in FIGS. 2A-2F. Still referring to FIG. 1, active through silicon via (TSV) 8 includes TSV opening 12 filled with conductive material 10 and carrying signal 14. Conductive material 10 may be copper, aluminum or other suitable materials and active TSV 8 enables wafer-to-wafer interconnect compatible with 3D wafer level packaging. Signal 14 may be a noisy signal. Noise is represented as electrical noise 16 which propagates through semiconductor substrate 2 and would adversely affect the performance of active semiconductor device 22 if not for the presence of isolation structure 20.

[0012] Active semiconductor device 22 includes transistor 24 in the illustrated embodiment but active semiconductor device 22 may be other active semiconductor devices in other exemplary embodiments. In exemplary embodiments in which active semiconductor device 22 is a transistor, it may be various different types of transistors such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), a FinFET, or various other P-type or N-type transistors or other active semiconductor devices. The illustrated doping types and electrical connections of FIG. 1 are intended to be exemplary only.

[0013] Isolation structure 20 includes TSV isolation structure 23 which is formed of TSV opening 26 surrounded by surrounding dopant impurity region 28B and filled with conductive material 10. TSV openings 26 and 12 are formed simultaneously and may advantageously be filled with conductive material 10 simultaneously. The sidewalls of TSV openings 12 and 26 include oxide liner 30. Surrounding dopant impurity regions 28A and 28B surround TSV openings 12 and 26, respectively. The dopant impurity regions 28A, 28B may be P-type dopant impurity regions or N-type dopant impurity regions. In one embodiment, both dopant impurity regions 28A and 28B are P-type dopant impurity regions. In another embodiment, both dopant impurity regions 28A and 28B are N-type dopant impurity regions. In another embodiment, dopant impurity regions 28A and 28B are of different dopant impurity types. Surface dopant impurity region 32 may be an N-type dopant impurity region or a P-type dopant impurity region and will be the same dopant impurity type as surrounding dopant impurity region 28B according to various exemplary embodiments. In the illustrated embodiment, surface dopant impurity region 32 is advantageously a P+ dopant impurity region coupled to ground 34. According to the exemplary embodiment in which surface dopant impurity region 32 and surrounding dopant impurity region 28B are N-type dopant impurity regions, surface dopant impurity region 32 will be advantageously coupled to V_DD.

[0014] Still referring to FIG. 1, TSV isolation structure 23 is electrically coupled to surface dopant impurity region 32 and therefore also to ground 34 by conductive surface lead 38 because surrounding dopant impurity region 28B and surface dopant impurity region 32 are spaced apart, but it will be seen in other exemplary embodiments that surrounding dopant impurity region 28B may overlap surface dopant impurity region 32 and obviate the need for surface conductive lead 38.

[0015] Now turning to FIGS. 2A-2F, FIG. 2A shows semiconductor substrate 100 having top surface 102 and bottom surface 104. Semiconductor substrate 100 may be formed of silicon or other suitable materials and it may be a P-type or N-type material. Active semiconductor device 108 is formed in and on top surface 102 and includes well region 110, source/drain regions 112, and gate 114 and active semiconductor device 108 is a transistor in the illustrated exemplary embodiment. Active semiconductor device 122 includes gate 124 and source/drain regions 126. Active semiconductor devices 108, 122 are intended to be exemplary only. Also formed extending downwardly from top surface 102 is surface dopant impurity region 118 which will be coupled to electrical coupling 120, the dashed line indicating that the coupling has not yet been made. Surface dopant impurity region 118 may be an N-type dopant impurity region or it may be a P-type dopant impurity region. According to the embodiment in which surface dopant impurity region 118 is an N-type dopant impurity region, electrical coupling 120 will be to V_DD and according to the exemplary embodiment in which surface dopant impurity region 118 is a P-type dopant impurity region, electrical coupling 120 will be to ground.

[0016] FIG. 2B shows the structure of FIG. 2A after dielectric layer 130 has been formed over top surface 102. Various suitable materials such as used as interlevel dielectric layers may be used as dielectric layer 130. A photoresist layer may be formed over dielectric layer 130 and patterned and a subsequent etching process may be carried out to form the structure shown in FIG. 2C.

[0017] FIG. 2C shows the structure of FIG. 2B after via opening 134 has been formed extending downwardly from top surface 102. Various etching processes may be used. Via opening 134 includes bottom 136 that does not reach bottom surface 104 at this stage of processing and also extends through dielectric layer 130. Via opening 134 may include a width of about 4-10 microns and the width may be about 6 microns in one exemplary embodiment. Depth 140 may take on various values and may range from about 50-80 microns, preferably 60 microns, in one exemplary embodiment. It should be noted that the expressed values for the width and for depth 140, are exemplary only. Via opening 134 is spaced from surface dopant impurity region 118 by spacing 142 which may be various distances in various exemplary embodiments. Spacing 142 will determine whether the surrounding dopant impurity region to be formed as shown in FIG. 2D, will overlap with surface dopant impurity region 118. A further via opening (not shown) is advantageously formed to the left of via opening 134 in the illustration of FIG. 2C, the further via opening to serve as an active, signal carrying TSV (such as TSV opening 12 shown in FIG. 1) that will be isolated from active semiconductor devices 108, 122 by the TSV isolation structure to be formed using via opening 134.

[0018] FIG. 2D shows surrounding dopant impurity region 146 surrounding via opening 134 and extending downwardly to bottom 136. Various methods may be used to form surrounding dopant impurity region 146 which may be an N-type or P-type region. In the exemplary embodiment, surrounding dopant impurity region 146 overlaps surface dopant impurity region 118 at overlap region 152. Surrounding dopant impurity region 146 and surface dopant impurity region 118 will advantageously be of the same dopant type. In one exemplary embodiment, an angled ion implantation process may be used to introduce dopant impurities into substrate 100 around via opening 134 to form surrounding dopant impurity region 146. This is illustrated by arrows 150 illustrative of an angled ion implantation process. Angled ion implantation processes are known in the art. According to another exemplary embodiment, a plasma doping operation may be used to form surrounding dopant impurity regions 146 and the plasma doping process may be carried out in-situ with the etching operation used to form via opening 134, or separately. According to either the angled ion implantation doping embodiment or the plasma doping embodiment, the doping operation may be carried out with patterned dielectric layer 130 still in place and also with a photoresist layer used to pattern dielectric layer 130, still in place. Various other methods for introducing dopant impurities into sidewalls 138 of via opening 134 may be used. Surrounding dopant impurity region 146 may include various depths and in one exemplary embodiment, thickness 154 may range from about 10 to about 30 microns.

[0019] According to the embodiment in which a further via opening is advantageously formed to the left of via opening 134, the doping operation simultaneously forms surrounding dopant impurity regions of the same impurity type around the further via opening, in one embodiment. The further via opening may be an active, signal carrying TSV such as TSV opening 12 shown in FIG. 1, in one embodiment. In another embodiment in which a further via opening (not shown) is advantageously formed to the left of via opening 134, two separate doping operations may be used. In particular, two different doping operations may be used in conjunction with an interceding patterning operation, to separately form one of the surrounding dopant impurity regions to include a first impurity type and the other of the surrounding dopant impurity regions to include a second impurity type which may be the opposite impurity type.

[0020] The structure in FIG. 2E shows the structure of FIG. 2D after a thermal oxidation process has been carried out to form oxide liner 158 and after a backgrinding or backlapping operation has been carried out to upwardly recede the bottom surface of semiconductor substrate 100. The thickness of semiconductor substrate 100 is diminished by the backgrinding or backlapping operation and backgrinded surface 160 results. The via opening (134) that had extended into semiconductor substrate 100 now extends completely through semiconductor substrate 100 forming TSV opening 164.

[0021] TSV opening 164 will be substantially filled with a conductive material such as conductive material 168 such as shown in FIG. 2F. TSV isolation structure 170 includes oxide liner 158, surrounding dopant impurity region 146 and TSV opening 164 filled with conductive material 168 and will serve as a TSV isolation structure 170 as it is coupled to electrical coupling 120 through substrate dopant impurity region 118. In other exemplary embodiments, surrounding dopant impurity region 146 does not overlap with surface dopant impurity region 118. When surface dopant impurity region 118 is an N-type dopant impurity region, electrical coupling 120 is to V_DD and when surface dopant impurity region 118 is a P-type dopant material, electrical coupling 120 will be ground. As discussed supra, TSV isolation structure 170 isolates active semiconductor devices 108, 122 from electrical noise such as may be generated by a signal carrying active TSV disposed to the left of TSV isolation structure 170.

[0022] According to the embodiment in which a further via opening (not shown in FIG. 2E) is formed to the left of via opening 134, the thermal oxidation process and backgrinding or backlapping operations that are performed as described above, will also produce an oxide liner around the further via opening such as oxide liner 30 surrounding TSV opening 12 as in FIG. 1.

[0023] FIGS. 3A and 3B are cross-sectional views showing another exemplary embodiment, FIG. 3A representing the same step such as the processing step illustrated in FIG. 2D and FIG. 3B illustrating the same process step such as the process step illustrated in FIG. 2F. In FIG. 3A, depth 174 of surrounding dopant impurity region 146 is less than depth 140 of via opening 134. FIG. 3A also shows the electrical connection as ground connection 120A such as used according to the exemplary embodiment in which surface dopant impurity region 118 is a P-type dopant impurity. The structure illustrated in FIG. 3B is then produced after at least an oxidation process, a backgrinding process and a conductive material formation process are carried out upon the structure shown in FIG. 3A. The exemplary structure shown in FIG. 3B differs from the exemplary embodiment shown in FIG. 2F because TSV isolation structure 170 including oxide liner 158 extends through semiconductor substrate 100 and reaches backgrinded surface 160, however surrounding dopant impurity region 146 does not extend to backgrinded surface 160. Depth 174 of surrounding dopant impurity region 146 is less than thickness 178 of the backgrinded semiconductor substrate 100.

[0024] FIGS. 4 and 5 are top views illustrating two exemplary embodiments of arrays of TSV isolation structures used to isolate active TSV structures from active semiconductor devices. FIG. 4 shows array configuration 200 and FIG. 5 shows array configuration 220. In each array, active TSVs 204 are separated from active semiconductor devices 202 by one or more TSV isolation structures arranged in an array. Active TSVs 204 are TSVs that carry signals or perform other active electrical functions and may include surrounding dopant impurity regions 210, although surrounding dopant impurity regions 210 may not be present in some embodiments. In FIG. 4, array configuration 200 includes a row of TSV isolation structures 206 including surrounding dopant impurity regions 216 and a row of TSV isolation structures 208 with surrounding dopant impurity regions 218. FIG. 5 shows an inner ring of TSV isolation structures 206 with surrounding dopant impurity regions 216 and an outer ring of TSV isolation structures 208 with corresponding surrounding dopant impurity regions 218.

[0025] Referring to FIGS. 4 and 5, according to a first embodiment, TSV isolation structures 206 may be N-type TSV isolation structures with corresponding surrounding dopant impurity regions 216 being N-type dopant impurity regions coupled to V_DD with TSV isolation structures 208 being P-type TSV isolation structures with corresponding surrounding dopant impurity regions 218 being P-type dopant impurity regions coupled to ground. According to this first embodiment, surrounding dopant impurity region 210 may be either P-type or N-type dopant impurity regions. According to another exemplary embodiment, surrounding dopant impurity region 210, and each of TSV isolation structures 206 and 208 and corresponding surrounding dopant impurity regions 216 and 218 are P-type dopant impurity regions coupled to ground. According to yet another exemplary embodiment, surrounding dopant impurity region 210, and each of TSV isolation structures 206 and 208 and corresponding surrounding dopant impurity regions 216 and 218 are N-type dopant impurity regions coupled to V_DD. According to yet another exemplary embodiment, TSV isolation structures 206 may be P-type TSV isolation structures with corresponding surrounding dopant impurity regions 216 being P-type dopant impurity regions coupled to ground with TSV isolation structures 208 being N-type TSV isolation structures with corresponding surrounding dopant impurity regions 218 being N-type dopant impurity regions coupled to V_DD. According to this embodiment, surrounding dopant impurity regions 210 may be either P-type or N-type dopant impurity regions.

[0026] Active semiconductor device 202 may represent one or a plurality of any of various active semiconductor devices that may be formed within an integrated circuit and it should be understood that the configurations of the arrays shown in FIGS. 4 and 5 are intended to be exemplary only and may take other shapes in other exemplary embodiments.

[0027] According to one aspect, a semiconductor device is provided. The semiconductor device comprises an active semiconductor device formed on a surface of a semiconductor substrate and an isolation through silicon via (TSV) extending through the semiconductor substrate and laterally spaced from the active semiconductor device and next to a surface dopant impurity region of a first dopant impurity type formed in the surface between the isolation TSV and the active semiconductor device. The semiconductor device further comprises an isolation TSV surrounded laterally by a surrounding dopant impurity region, the surrounding dopant impurity region being one of a P-type dopant impurity region coupled to ground and an N-type dopant impurity region coupled to V_DD.

[0028] According to another aspect, provided is a method for forming a semiconductor device. The method comprises: providing a semiconductor substrate with a surface having an active semiconductor device disposed thereon and a surface dopant impurity region of a first dopant impurity type disposed therein; forming a through silicon via (TSV) opening next to the surface dopant impurity region and extending downwardly from the surface and into the semiconductor substrate, the surface dopant impurity region disposed between the TSV opening and the active semiconductor device; forming a surrounding dopant impurity region surrounding the TSV opening, the surrounding dopant impurity region being one of a P-type dopant impurity region and an N-type dopant impurity region; and electrically coupling the surrounding dopant impurity region by one of coupling the P-type dopant impurity region to ground when the surrounding dopant impurity comprises a P-type dopant impurity region, and coupling the N-type dopant impurity region to V_DD when the surrounding dopant impurity comprises an N-type dopant impurity region.

[0029] According to another aspect, a method for forming a semiconductor device is provided. The method comprises providing a semiconductor substrate with a surface having an active semiconductor device disposed thereon; forming a plurality of through silicon vias (TSV) extending through the semiconductor substrate, the plurality of TSVs including an active TSV including a conductive structure carrying an electrical signal therein, an array of N-type TSV isolation structures surrounded by corresponding N-type surrounding dopant impurity regions and an array of P-type TSV isolation structures surrounded by corresponding P-type surrounding dopant impurity regions; and coupling the N-type TSV isolation structures to V_DD and coupling the P-type TSV isolation structures to ground, wherein the active TSV is separated from the active semiconductor device by at least some of the N-type TSV isolation structures and the P-type TSV isolation structures.

[0030] The preceding merely illustrates the principles of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the disclosure and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended expressly to be only for pedagogical purposes and to aid the reader in understanding the principles of the disclosure and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.

[0031] This description of the exemplary embodiments is intended to be read in connection with the figures of the accompanying drawing, which are to be considered part of the entire written description. In the description, relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.

[0032] Although the disclosure has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the disclosure, which may be made by those skilled in the art without departing from the scope and range of equivalents of the disclosure.