Patent Publication Number: US-8987839-B2

Title: Ground shield structure and semiconductor device

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. CN201310232109.3, filed on Jun. 9, 2013, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to the field of semiconductor technology and, more particularly, relates to ground shield structures and semiconductor devices having the ground shield structures. 
     BACKGROUND 
     In current integrated circuits (ICs), such as complementary metal-oxide-semiconductor radio-frequency (CMOS RF) circuits, inductor is an important electrical device. Performance parameters of an inductor can directly affect performance of an IC. Conventionally, most inductors in ICs are planar inductors, such as planar spiral inductors. The planar inductors are formed by winding a metal wire on a surface of a substrate or a dielectric layer. In comparison with traditional coils or coil inductors, the planar inductors have advantages such as low cost, ease of integration, low noise and low power consumption. More importantly, the planar inductors can be compatible with current IC processes. 
     Performance of an inductor is characterized by a quality factor Q of the inductor. The quality factor Q is a ratio of energy stored in the inductor to energy loss during each oscillation cycle. The higher the quality factor Q of the inductor, the greater the efficiency and the better the performance of the inductor. The energy loss of the inductor is an important factor that affects the value of Q. Substrate loss in an IC accounts for the largest proportion of the energy loss of the inductor. That is, the substrate loss is an important factor that affects the quality factor Q of the inductor. 
     Conventionally, on one hand, a planar inductor is disposed on an IC, so electric field lines can enter a substrate and lead to electric charge movements in the substrate to generate a coupling substrate current. The current can lead to ohmic loss in the substrate. On the other hand, an alternating current in the inductor generates an alternating magnetic field (i.e., an induced alternating magnetic field), which can vertically enter the substrate through the surface of the substrate to generate an alternating eddy current in the substrate. The eddy current can dissipate electric energy (converted from magnetic energy) as Joule heat, which causes eddy current loss. The ohmic loss and the eddy current loss can result in a significant substrate loss, which can significantly reduce the quality factor Q. 
     Therefore, currently, a ground shield structure is provided between the inductor and the substrate. The ground shield structure serves to shield the electric field lines and the induced magnetic field lines of the inductor, such that the electric field lines and the induced magnetic field lines can terminate at the ground shield structure instead of entering the substrate. The substrate loss can thus be reduced. 
     Although the existing ground shield structure can reduce the substrate loss, in practical applications, after the existing ground shield structure is introduced into a semiconductor device containing the inductor, the quality factor Q of the inductor is not improved. To the contrary, the quality factor Q of the inductor is even reduced in some bands of operating frequency of the inductor. 
     Referring to  FIG. 1 , a curve 01 corresponds to a Q value of an inductor not having a ground shield structure, and a curve 02 corresponds to a Q value of an inductor having an existing ground shield structure. In an operating frequency band of the inductor that is higher than 10×10 9  Hz, the Q value of the inductor having the ground shield structure is not significantly greater than the Q value of the inductor not having the ground shield structure. Moreover, in an operating frequency band of the inductor that is lower than 10×10 9  Hz, the Q value of the inductor having the ground shield structure is lower than the Q value of the inductor not having the ground shield structure. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     One aspect of the present disclosure includes a ground shield structure. An exemplary structure can include a substrate and a dielectric layer disposed on the substrate. The structure can further include multiple conductive rings disposed in the substrate, in the dielectric layer, and/or on the dielectric layer. Each conductive ring of the multiple conductive rings can have openings of about three or more, and the openings of the each conductive ring can divide the multiple conductive rings into a plurality of sub-conductive rings arranged spaced apart. The structure can further include a ground ring electrically connected to each of the plurality of sub-conductive rings. 
     Another aspect of the present disclosure includes a method for forming a ground shield structure: An exemplary method can include providing a dielectric layer on a substrate. The method can further include configuring multiple conductive rings in the substrate, in the dielectric layer, and/or on the dielectric layer. Each conductive ring of the multiple conductive rings can have openings of about three or more, and the openings of the each conductive ring can divide the multiple conductive rings into a plurality of sub-conductive rings arranged spaced apart. The method can further include connecting a ground ring to each of the plurality of sub-conductive rings. 
     Yet another aspect of the present disclosure includes a semiconductor device. An exemplary device can include a ground shield structure and an induction device disposed on the ground shield structure. The structure can include a substrate and a dielectric layer disposed on the substrate. The structure can further include multiple conductive rings disposed in the substrate, in the dielectric layer, and/or on the dielectric layer. Each conductive ring of the multiple conductive rings can have openings of about three or more, and the openings of the each conductive ring can divide the multiple conductive rings into a plurality of sub-conductive rings arranged spaced apart. The structure can further include a ground ring electrically connected to each of the plurality of sub-conductive rings. 
     Other aspects or embodiments of the present disclosure can be understood by those skilled in the art in light of the description, the claims, and the drawings of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a relationship between an operating frequency and a Q value of each of an inductor not having a ground shield structure and an inductor having an existing ground shield structure; 
         FIG. 2  depicts a top view of an exemplary ground shield structure (e.g., including multi-ring conductive rings, a ground ring, and/or interconnects) in accordance with various disclosed embodiments; 
         FIG. 3  depicts a cross-sectional view of the exemplary ground shield structure along an AB direction as shown in  FIG. 2  in accordance with various disclosed embodiments; 
         FIG. 4  depicts a cross-sectional view of another exemplary ground shield structure in accordance with various disclosed embodiments; 
         FIG. 5  depicts a top view of another exemplary ground shield structure (e.g., including multi-ring conductive rings, a ground ring, and/or interconnects) in accordance with various disclosed embodiments; 
         FIG. 6  depicts a cross-sectional view of the exemplary ground shield structure along an AB direction as shown in  FIG. 5  in accordance with various disclosed embodiments; 
         FIG. 7  depicts a cross-sectional view of another exemplary ground shield structure in accordance with various disclosed embodiments; 
         FIG. 8  depicts a cross-sectional view of another exemplary ground shield structure in accordance with various disclosed embodiments; 
         FIG. 9  depicts a cross-sectional view of another exemplary ground shield structure in accordance with various disclosed embodiments; 
         FIG. 10  depicts a cross-sectional view of another exemplary ground shield structure in accordance with various disclosed embodiments; 
         FIGS. 11-12  depict top views of an exemplary planar spiral inductor in accordance with various disclosed embodiments; and 
         FIG. 13  depicts a relationship between an operating frequency and a Q value of each of an inductor having an exemplary ground shield structure in accordance with various disclosed embodiments, an inductor not having a ground shield structure, and an inductor having an existing ground shield structure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary embodiments of the disclosure, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     A ground shield structure is often provided between an inductor and a substrate. The ground shield structure may not improve a quality factor Q of the inductor. When a high-frequency signal is applied to the inductor, the inductor can introduce a significant parasitic effect into the ground shield structure. The parasitic effect can include a parasitic resistance and a parasitic capacitance, which can result in a large amount of energy loss, thus reducing the quality factor Q of the inductor. 
     Various embodiments provide a ground shield structure and a semiconductor device having the ground shield structure. For example,  FIG. 2  depicts a top view of an exemplary ground shield structure (e.g., including multi-ring conductive rings, a ground ring, and/or interconnects) in accordance with various disclosed embodiments.  FIG. 3  depicts a cross-sectional view of the exemplary ground shield structure along an AB direction as shown in  FIG. 2  in accordance with various disclosed embodiments. 
     Referring to  FIGS. 2-3 , a ground shield structure  300  can include a substrate  301 , a dielectric layer  302  disposed on the substrate  301 , and conductive rings  303  in the substrate  301 . The conductive rings  303  can include multiple rings, i.e., having a multi-ring structure. In one embodiment, the conductive rings  303  can include first-active rings. Adjacent first-active rings can be separated by annular isolation structures  306 . Each conductive ring  303  can have a plurality of openings  305 , e.g., about 8 openings  305  in the example as shown in  FIG. 2 . The openings  305  can divide each conductive ring  303  into a plurality of spaced sub-conductive rings  331 . 
     Further, the ground shield structure  300  can include a ground ring  304 . The ground ring  304  can be a third-active ring located in the substrate  301  and surrounding the conductive rings  303 . The ground ring  304  and the conductive rings  303  can be separated by the annular isolation structures  306 . For illustrative purposes, one ground ring is shown in this example. However, in various embodiments, there can be more than one ground rings, without limitation. 
     In addition, the ground shield structure  300  can include interconnects  307  located on the dielectric layer  302 . The ground ring  304  can be electrically connected to the interconnects  307  via conductive plugs  308 . The sub-conductive rings  331  of two adjacent conductive rings  303  in a radial direction can be electrically connected to one of the interconnects  307  via the conductive plugs  308 . 
     Referring to  FIG. 2 , in one embodiment, the conductive rings  303  can have a regular (e.g., symmetric) shape, for example, an octagonal shape. Correspondingly, the conductive rings  303  can have about 8 openings. That is, an opening can be formed at each side of the octagonal shape, so a pattern of the conductive rings  303  can be more symmetric. However, in other embodiments, the number of the openings may not necessarily correspond to the shape of the conductive rings  303 . For conductive rings  303  having any shape, the number of the openings of the conductive rings  303  can be any number greater than or equal to about 3. In various embodiments, the openings can be symmetrically configured in each of the conductive rings  303 . 
     In various embodiments, each of the conductive rings  303  can serve as a parasitic resistor between the substrate  301  and an inductor. When the ground shield structure  300  is placed under the inductor and a high-frequency signal is applied to the inductor, the high-frequency signal in the inductor can generate an induced alternating magnetic field perpendicular to a surface of the substrate  301 . The induced alternating magnetic field can be applied to the parasitic resistor, causing electric charge movements in the parasitic resistor, which can result in an energy loss. 
     In various embodiments, the openings  305  can divide each conductive ring  303  into a plurality of spaced sub-conductive rings  331 . Thus, a parasitic resistance of each conductive ring  303  can be reduced, in comparison with a conductive ring without openings. A reduction in the parasitic resistance of each conductive ring  303  can cause a reduction of a total parasitic resistance of the multi-ring conductive rings  303 , which can reduce the energy loss of the inductor caused by conventional ground shield structures and significantly increase the quality factor Q of the resultant inductor. 
     Generally, on one hand, the more the openings  305  of the conductive rings  303 , the lower the parasitic resistance. On the other hand, if there are too many openings  305 , many induced magnetic field lines may enter the substrate  301  through the opening  305  and a desired shielding effect may not be achieved. For example, the number of openings  305  of the conductive rings  303  in  FIG. 2  can be greater than or equal to 3, and/or less than or equal to 8, and the desired shielding effect may be achieved. 
     In various embodiments, when the inductor is disposed on the ground shield structure  300 , and a high-frequency signal is applied to the inductor coil (or the inductor), electric potentials at junctions between the interconnect  307  and the sub-conductive rings  331  can be fixed. There can be no electric charge movement in the interconnect  307  between two adjacent junctions. However, under the high-frequency signal, an electric potential away from one of the junctions can be unequal, i.e., unequal to the electric potential at the junction. So a potential difference can be established, and mobile charge can be induced in a sub-conductive ring  331  away from the junction. 
     Therefore, under the high-frequency signal, the sub-conductive rings  331  of two adjacent conductive rings  303  configured with a same interconnect  307  can face each other in the radial direction to form a coupling capacitor. Each sub-conductive ring  331  can be regarded as an electrode plate of the coupling capacitor. Thus, the multiple sub-conductive rings  331  electrically connected to the same interconnect  307  can form multiple coupling capacitors between each other. For example, two adjacent sub-conductive rings  331  can form one coupling capacitor. The interconnect  307  can electrically connect the multiple coupling capacitors, which can be equivalent to electrically connecting the multiple coupling capacitors in series. 
     After connecting the multiple coupling capacitors in series, a total coupling capacitance can be a parasitic capacitance between the substrate  301  and the inductor. Connecting the multiple coupling capacitors in series can reduce the total coupling capacitance, which can equivalently reduce the parasitic capacitance between the substrate  301  and the inductor. The reduction of the parasitic capacitance can result in a reduction of the energy loss of the inductor in the ground shield structure, thus increasing the quality factor Q of the inductor. 
     Referring to  FIG. 2 , to further enhance the shielding effect, in some embodiments, the multi-ring conductive rings  303  can be concentric electrically conductive rings. A distance between two adjacent conductive rings  303  can be equal. Thus, the electric field lines and the induced magnetic field lines of the inductor can be uniformly shielded along circumferential and/or radial directions. Further, each of the conductive rings  303  can have an equal number of openings  305 , e.g., about 8. The openings  305  can be equally spaced. The openings  305  of two adjacent conductive rings  303  can have a one-to-one correspondence with (i.e., can be consistent with) each other. In various embodiments, the openings in each of adjacent conductive rings are consistent in radial directions. Thus, along the circumferential and radial directions, the electric field lines and the induced magnetic field lines of the inductor can be uniformly shielded. 
     In other embodiments, when each of the multiple conductive rings  303  does not have an equal number of the openings  305 , a shielding effect can be achieved, but the achieved shielding effect may not be uniform and may not be satisfactory. In addition, each interconnect  307  can electrically connect midpoints of two adjacent sub-conductive rings  331  in the radial direction, so distribution density of the interconnects  307  can be uniform. This can result in a desired and uniform shielding effect. 
     Referring to  FIGS. 2-3 , in one embodiment, the conductive rings  303  and the ground ring  304  can be active rings located in the substrate  301 . Therefore, the conductive rings  303  and the ground ring  304  can be formed in a same step, which can save time and cost for manufacturing. 
     For example, multiple spaced annular isolation structures  306  can first be formed in the substrate  301 . Of any two annular isolation structures  306 , one annular isolation structure  306  can be enclosed by another annular isolation structure  306 . The substrate  301  between the two adjacent annular isolation structures  306  can be doped with impurities to form the active rings (e.g., using a diffusion process). 
     Next, the plurality of openings  305  can be formed in each of the active rings. For example, an outermost active ring can be the ground ring  304 . The ground ring  304  can have about 2 openings, which can prevent the induced magnetic field lines from generating an eddy current in the ground ring  304 . The active rings enclosed by the outermost active ring can be the conductive rings  303 . The conductive rings  303  can have about 8 openings  305 . 
     The dielectric layer  302  can then be deposited. The conductive plugs  308  can be formed in the dielectric layer  302  to electrically connect to the ground ring  304  and the sub-conductive rings  331 . 
     Further, the interconnects  307  can be formed on the dielectric layer  302 . Each of the interconnects  307  can electrically connect to the sub-conductive rings  331  of the conductive rings  303  and the ground ring  304  in the radial direction. Corresponding to a number of the sub-conductive rings  331  in each conductive ring  303  (e.g., about 8), about 8 interconnects  307  can be formed. 
     In one embodiment, the interconnects  307  can be made of a material including aluminum, and can be formed by a process including a deposition step and/or an etching step. In another embodiment, the interconnects  307  can be made of a material including copper, and can be formed by a process including a dual-Damascene process. In one embodiment, the interconnects  307  and the conductive plugs  308  can be formed in a same step. 
     In some embodiments, a number of the conductive rings  303  can be about 8, which is not limited in the present disclosure. In other embodiments, the number of the conductive rings  303  can range from about 2 to about 100, e.g., about 10, about 20, or about 50. 
     In some embodiments, the conductive rings  303  can have a regular (e.g., symmetric) octagonal shape. In other embodiments, the conductive rings  303  can have a triangular, square, circular shape, etc. The shape of the conductive rings  303  and the shape of the ground ring  304  can be the same. For example, in one embodiment, the conductive rings  303  and the ground ring  304  can have an octagonal shape. In other embodiments, the shape of the conductive rings  303  and the shape of the ground ring  304  can be different. When the conductive rings  303  and the ground ring  304  have the same shape, the formed pattern can be more regular (e.g., symmetric). In one embodiment, each of the conductive rings  303  and the ground ring  304  can have a width ranging from about 0.1 micron to about 100 microns. 
     According to various embodiments, the process for forming the ground ring  304  and the multi-ring conductive rings  303  can be compatible with CMOS processes. For example, the substrate  301  can include one or more materials used in CMOS process, e.g., silicon, germanium, silicon-on-insulator, silicon carbide, silicon-germanium, gallium nitride, glass, etc. In one embodiment, the substrate  301  can be a p-type silicon substrate. 
       FIG. 4  depicts a cross-sectional view of another exemplary ground shield structure in accordance with various disclosed embodiments. In this example, conductive rings can be polycrystalline silicon (or polysilicon) rings in a dielectric layer. 
     Referring to  FIG. 4 , conductive rings  403  can be polysilicon rings in a dielectric layer  402 . The conductive rings  403  can include multiple rings, i.e., having a multi-ring structure. Two adjacent conductive rings  403 , or two adjacent sub-conductive rings can be separated by the dielectric layer  402 . The conductive rings  403  can be separated from a substrate  401  by the dielectric layer  402 . The sub-conductive rings of each of the conductive rings  403  can be electrically connected to interconnects  407  via first conductive plugs  418 . A number of the first conductive plugs  418  can be equal to a number of the sub-conductive rings. A ground ring  404  can be a third-active ring in the substrate  401 , and can be electrically connected to the interconnects  407  via second conductive plugs  428 , and separated from a surrounding portion of the substrate  401  by annular isolation structures  406 . On a surface of the substrate  401 , a projection of the conductive rings  403  can be within a range of a projection of the ground ring  404 . 
     In addition, parameters of the conductive rings  403 , e.g., shape, number, number of openings, and arrangement of the openings can be similar to or the same as described above in accordance with various embodiments. A shielding effect achieved by the ground shield structure in this example can be the same as or similar to the shielding effect achieved by the ground shield structures as described above in accordance with various embodiments. 
     In this case, a method for forming the ground shield structure in accordance with various embodiments can include the following steps. First, the third-active ring can be formed in the substrate  401  as the ground ring  404 . The annular isolation structures  406  can be formed on both sides of the third-active ring. 
     Next, a first dielectric layer can be disposed on the substrate  401  and a polysilicon layer can be disposed on the first dielectric layer. The polysilicon layer can be patterned to form the multi-ring polysilicon rings. On the surface of the substrate  401 , the projection of the polysilicon rings can be enclosed by the projection of the ground ring  404 . The polysilicon rings can have a plurality of openings and can serve as the conductive rings  403 . 
     A second dielectric layer can then be deposited, and the first conductive plugs  418  can be formed in the second dielectric layer to electrically connect to the sub-conductive rings. The second conductive plugs  428  of the third-active ring can be formed in the first dielectric layer and the second dielectric layer. The first dielectric layer and the second dielectric layer together can form the dielectric layer  402 . The interconnects  407  can be formed on the dielectric layer  402 . A location and structure of the interconnects  407 , and positions of junctions between the interconnects  407  and the sub-conductive rings and the ground ring can be similar to or the same as described above in accordance with various embodiments. 
       FIG. 5  depicts a top view of another exemplary ground shield structure (e.g., including multi-ring conductive rings, a ground ring, and/or interconnects) in accordance with various disclosed embodiments.  FIG. 6  depicts a cross-sectional view of the exemplary ground shield structure along an AB direction as shown in  FIG. 5  in accordance with various disclosed embodiments. In this example, conductive ring can be metal rings. 
     In some embodiments, referring to  FIGS. 5-6 , conductive rings  503  can be first metal rings on a dielectric layer  502 . The conductive rings  503  can include multiple rings, i.e., having a multi-ring structure. The conductive rings  503  and interconnects  507  can be in a same plane and connected with each other, and can be separated from a substrate  501  by the dielectric layer  502 . 
     A ground ring  504  can include a third-active ring  541  in the substrate  501  and a second metal ring  542  above the third-active ring  541 . Annular isolation structures  506  can be formed on both sides of the third-active ring  541 , and can separate the third-active ring  541  from other portions of the substrate  501 . The second metal ring  542  can be electrically connected to the third-active ring  541  via conductive plugs  508 . The second metal ring  542  and the conductive rings  503  can be in the same plane with the interconnects  507  and connected with each other. 
     In this case, a method for forming the ground shield structure in accordance with various embodiments can include the following steps. First, the third-active ring  541  can be formed in the substrate  501 . The annular isolation structures  506  can be formed on both sides of the third-active ring  541 . 
     Next, the dielectric layer  502  can be formed on the substrate  501 . The conductive plugs  508  can be formed in the dielectric layer  502  to electrically connect the third-active ring  541 . 
     The second metal ring  542 , the first metal rings enclosed by the second metal ring  542 , and the interconnects  507  connecting the second metal ring  542  and the first metal rings, can then be formed on the dielectric layer  502 . The first metal rings can be used as the conductive rings  503 . Sub-conductive rings  531  of adjacent conductive rings  503  can be connected by one of the interconnects  507  in the radial direction. 
     Parameters of the conductive rings  503 , e.g., shape, number, number of openings, and arrangement of the openings can be similar to or the same as described above in accordance with various embodiments. A shielding effect achieved by the ground shield structure in this example can be the same as or similar to the shielding effect achieved by the ground shield structures as described above in accordance with various embodiments. 
     In other embodiments, the first metal rings can be in a different plane from the interconnects. The first metal rings can be in the dielectric layer and electrically connected to the interconnects via the conductive plugs (e.g., as shown in  FIG. 4 ). In this case, the first metal rings and the second metal ring can be in a same plane, and can be electrically connected to the interconnects via the conductive plugs. Optionally, the second metal ring can be electrically connected to the third-active ring via the conductive plugs. In one embodiment, the ground ring can include the third-active ring without the second metal ring, and can be electrically connected to the interconnects. 
     In this case, a density of metal in the ground shield structure can be significantly reduced. So the energy loss of the inductor in the conductive rings  503  can be reduced, and the quality factor Q can be increased. Moreover, the first metal rings, the second metal ring  542  and the interconnects  507  can be formed in a same process. On one hand, process steps can be saved and manufacturing efficiency can be increased. On the other hand, conductive plug structures for connecting the sub-conductive rings  531  and the interconnects  507  can be omitted, so material consumption and fabrication cost can be reduced. 
       FIG. 7  depicts a cross-sectional view of another exemplary ground shield structure in accordance with various disclosed embodiments. In this example, in comparison with various disclosed embodiments (e.g., in  FIG. 4 ), the ground shield structure can further include second-active rings  605  in a substrate  601 . Two adjacent second-active rings  605  can be separated by an annular isolation structure  606 . Conductive rings  603  can be polysilicon rings in a dielectric layer  602 , and can be separated from the substrate  601  by the dielectric layer  602 . The conductive rings  603  and the second-active rings  605  can include multiple rings, i.e., having a multi-ring structure. The conductive rings  603  can be above the second-active rings  605  with a one-to-one correspondence in a direction perpendicular to a surface of the substrate  601 . The second-active rings  605  can have the similar or same parameters, e.g., shape, openings (e.g., a number of the openings), number (e.g., the number of the rings), and/or arrangement, as the conductive rings  603 . The ground ring  604  can be a third-active ring, and can enclose the second-active rings  605 . Sub-conductive rings can be electrically connected to interconnects  607  via first conductive plugs  618 . The ground ring  604  can be electrically connected to the interconnects  607  via second conductive plugs  628 . 
     In this example, the conductive rings  603  and the second-active rings  605  can be equivalent to double “barriers”, which can enhance a shielding effect of the ground shield structure. When the conductive rings  603  shield most of the electric field lines and/or induced magnetic field lines, and a small amount of the electric field lines and/or induced magnetic field lines pass through the second-active rings  605 , the second-active rings  605  can provide a further shielding effect to prevent an eddy current loss of the inductor in the substrate and achieve a better shielding effect. 
     Further details, variations of the ground shield structure, etc., and methods for forming the ground shield structure in this case can be similar to or the same as described above (e.g., in  FIG. 4 ) in accordance with various embodiments. 
       FIG. 8  depicts a cross-sectional view of another exemplary ground shield structure in accordance with various disclosed embodiments. In this example, in comparison with various disclosed embodiments (e.g., in  FIGS. 5-6 ), the ground shield structure can further include second-active rings  705  in a substrate  701 . Two adjacent second-active rings  705  can be separated by annular isolation structures  706 . Conductive rings  703  can be metal rings on a dielectric layer  702 , and can be separated from the substrate  701  by the dielectric layer  702 . The conductive rings  703  and the second-active rings  705  can include multiple rings, i.e., having a multi-ring structure. The conductive rings  703  can be above the second-active rings  705  with a one-to-one correspondence in a direction perpendicular to a surface of the substrate  701 . The second-active rings  705  can have the similar or same parameters, e.g., shape, openings (e.g., a number of the openings), number (e.g., the number of the rings), and/or arrangement, as the conductive rings  703 . 
     In this example, the second-active rings  705  can enhance the shielding effect of the ground shield structure. Further details, variations of the ground shield structure, etc., and methods for forming the ground shield structure in this case can be similar to or the same as described above (e.g., in  FIGS. 5-6 ) in accordance with various embodiments. 
       FIG. 9  depicts a cross-sectional view of another exemplary ground shield structure in accordance with various disclosed embodiments. In this example, conductive rings  803  can have a two-layer structure, including polysilicon rings  831  in a dielectric layer  802  and first metal rings  832 . The first metal rings  832  can be above the polysilicon rings  831  and electrically connected to the polysilicon rings  831  via first conductive plugs  818 . The polysilicon rings  831  and the first metal rings  832  can have a one-to-one correspondence (i.e., can be consistent) in a direction perpendicular to a surface of a substrate  801 . The polysilicon rings  831  can be separated from the substrate  801  by the dielectric layer  802 . 
     A ground ring  804  can include a third-active ring  841  in the substrate  801  and a second metal ring  842  above the third-active ring  841 . The second metal ring  842  can be electrically connected to the third-active ring  841  via second conductive plugs  828 . The third-active ring  841  can be separated from other portions of the substrate  801  by annular isolation structures  806 . The first metal rings  832 , the second metal ring  842  and interconnects  807  can be in a same plane, and can be formed in a same process. The interconnects  807  can be connected to the first metal rings  832  and the second metal ring  842  as a whole. 
     In this case, the conductive rings  803  having the two-layer structure can enhance the shielding effect of the ground shield structure. Further details, variations of the ground shield structure, etc., and methods for forming the ground shield structure in this case can be similar to or the same as described above (e.g., in  FIGS. 2-8 ) in accordance with various embodiments. 
       FIG. 10  depicts a cross-sectional view of another exemplary ground shield structure in accordance with various disclosed embodiments. In this example, in comparison with various disclosed embodiments (e.g., in  FIG. 9 ), the ground shield structure can further include second-active rings  905  in a substrate  901 . Adjacent second-active rings  905  can be separated by annular isolation structures  906 . 
     Further details, variations of the ground shield structure, etc., and methods for forming the ground shield structure in this case can be similar to or the same as described above (e.g., as shown in  FIG. 9 ) in accordance with various embodiments. 
     In this case, the shielding effect of the ground shield structure can be further enhanced in comparison with various disclosed embodiments (e.g., in  FIG. 9 ). 
     Accordingly, there is provided a semiconductor device including a ground shield structure in accordance with various disclosed embodiments. For example, the semiconductor device can include the ground shield structure, and an induction device on the ground shield structure. The induction device can include an inductor, a transformer and/or a balun. In one embodiment, the induction device can be an inductor, and the inductor can be a planar spiral inductor. 
       FIGS. 11-12  depict top views of an exemplary planar spiral inductor in accordance with various disclosed embodiments.  FIG. 11  depicts a top view of a first planar spiral ring of the inductor.  FIG. 12  depicts a top view of a second planar spiral ring of the inductor. 
     Referring to  FIG. 11 , the first planar spiral ring is located above an insulating layer (not shown). The insulating layer can be on a top of a ground shield structure. The first planar spiral ring can include a first metal ring  100 , a contact point  101 , a contact point  102 , a contact layer  110  and a contact layer  120 . 
     Referring to  FIG. 12 , the second planar spiral ring is located above the first planar spiral ring. There can be a dielectric layer between the first planar spiral ring and the second planar spiral ring. The second planar spiral ring can include a metal ring  200 , a contact point  201 , a contact point  202 , a contact layer  210  and a contact layer  220 . 
     The contact points of the first planar spiral ring and of the second planar spiral ring can be electrically connected via conductive plugs through the dielectric layer between the first planar spiral ring and the second planar spiral ring. For example, the contact point  101  and the contact point  201  can be electrically connected via conductive plug(s). The contact point  102  and the contact point  202  can be electrically connected via conductive plug(s). The contact layer  110  and the contact layer  210  can be electrically connected via conductive plug(s). The contact layer  120  and the contact layer  220  can be electrically connected via conductive plug(s). 
     In one embodiment, the planar spiral inductor (e.g., the first planar spiral ring and/or the second planar spiral ring) can have an octagonal shape, without limitation. For example, the first planar spiral ring and the second planar spiral ring can have a triangular, square, circular or octagonal shape, and the shape can be the same as or different from the conductive rings of the ground shield structure. The planar spiral inductor can include multiple planar spiral rings configured as a multi-layer structure. The shape of the rings of the planar spiral inductor (e.g., the first planar spiral ring and/or the second planar spiral ring) can be the same as or different from the rings (e.g., the conductive rings) of the ground shield structure. 
     In other embodiments, an induction device, e.g., a transformer, a balun, etc., can be formed above the ground shield structure. The induction device can generate a magnetic field to form an eddy current in the substrate and cause an eddy current loss. In various embodiments, in a direction perpendicular to a surface of the substrate, a projection of the induction device, e.g., the inductor, the transformer, the balun, etc., can be within the range of a projection of the ground shield structure. Thus, the magnetic field generated by the induction device that is perpendicular to the substrate can be within the range of the ground shield structure. 
       FIG. 13  depicts a Q value of an exemplary inductor in accordance with various disclosed embodiments, a Q value of an inductor not having a ground shield structure, and a Q value of an inductor having a conventional ground shield structure, versus an operating frequency. 
     As shown in  FIG. 13 , a curve 01 corresponds to a Q value of a disclosed inductor having a ground shield structure. A curve 02 corresponds to a Q value of an inductor not having the ground shield structure. A curve 03 corresponds to a Q value of an inductor having a conventional ground shield structure. As shown in  FIG. 13 , the Q value of the curve 01 reaches a maximum of about 26.8, at a frequency of about 10.4 GHz. The Q value of the curve 02 reaches a maximum of about 22.3, at a frequency of about 8.3 GHz. The Q value of the curve 03 reaches a maximum of about 22.3, at a frequency of about 9.3 GHz. Thus, the disclosed ground shield structure can effectively improve the Q value of the inductor, and the maximum of the Q value can be increased by more than about 17%. 
     The embodiments disclosed herein are exemplary only. Other applications, advantages, alternations, modifications, or equivalents to the disclosed embodiments are obvious to those skilled in the art and are intended to be encompassed within the scope of the present disclosure.