Abstract:
A semiconductor structure and a manufacturing method of the same are provided. The semiconductor structure includes a conductive layer, a conductive architecture and a dielectric layer. The conductive layer defines adjacent first openings. The conductive architecture surrounds a portion of the conductive layer between the first openings. The dielectric layer separates the conductive layer and the conductive architecture.

Description:
BACKGROUND 
     1. Technical Field 
     The disclosure relates in general to a semiconductor structure and a manufacturing method thereof, and particularly to a memory and a manufacturing method thereof. 
     2. Description of the Related Art 
     In recent years, the structures of semiconductor devices have been changed constantly, and the storage capacity of the devices has been increased continuously. Memory devices are used in storage elements for many products such as MP3 players, digital cameras, computer files, etc. As the application increases, the demand for the memory device focuses on small size and large memory capacity. For satisfying the requirement, a memory device having a high element density and a small size and the manufacturing method thereof is in need. 
     As such, it is desirable to develop a three-dimensional (3D) memory device with larger number of multiple stacked planes to achieve greater storage capacity, a small size, and yet having excellent property and stability. 
     SUMMARY 
     According to an embodiment of the present disclosure, a semiconductor structure is provided. The semiconductor structure comprises a conductive layer, a conductive architecture and a dielectric layer. The conductive layer defines adjacent first openings. The conductive architecture surrounds a portion of the conductive layer between the first openings. The dielectric layer separates the conductive layer and the conductive architecture. 
     According to another embodiment of the present disclosure, a semiconductor structure is provided. The semiconductor structure comprises stacked conductive strips, a conductive architecture, and a dielectric layer. The conductive architecture surrounds the conductive strips. The dielectric layer separates the conductive strips and the conductive architecture. 
     According to yet another embodiment of the present disclosure, a method for manufacturing a semiconductor structure is provided. The method comprises following steps. Insulating layers and conductive layers are stacked alternately. First openings are formed to pass through the insulating layers and the conductive layers. Portions of the insulating layers exposed by the first openings are removed to form second openings in the insulating layer and bigger than the first openings. A dielectric layer is formed to cover portions of the conductive layers exposed by the first openings and the second openings. Conductive architectures are formed on the dielectric layer. 
     The above and other embodiments of the disclosure will become better understood with regard to the following detailed description of the non-limiting embodiment(s). The following description is made with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  to  FIG. 5C  illustrate a process for manufacturing method for a semiconductor structure according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  to  FIG. 5C  illustrate a process for manufacturing method for a semiconductor structure according to one embodiment. The figures marked with “A” are top views of the semiconductor structure. The figures marked with “B” are cross-section views of the semiconductor structure along BB line and CC line, respectively. 
     Referring to  FIG. 1A  to  FIG. 1C , insulating layers  102  and conductive layers  104  are alternately stacked on a semiconductor substrate  106 . The semiconductor substrate  106  may comprise silicon, SOI, or other suitable materials or structures. The insulating layer  102  may comprise an oxide, a nitride, an oxynitride, such as silicon oxide, silicon nitride, silicon oxynitride, or other suitable dielectric materials. The conductive layers  104  (such as un-doped polysilicon) and the insulating layers  102  (such as silicon oxide) exposed by a hard mask  108  (such as silicon nitride) of the top layer the may be removed to define first openings  110  in the conductive layers  104  and the insulating layers  102  by an etching process comprising a wet etching, a dry etching, or other suitable methods. 
     Referring to  FIG. 2A  to  FIG. 2C , portions of the insulating layer  102  exposed by the first openings  110  are removed to define out second openings  112  in the insulating layer  102 , bigger than the first openings  110  of the conductive layer  104 , and communicated with the first openings  110 , by an etching process. The etching process for the second openings  112  has an etching selectivity to the insulating layer  102  higher than an etching selectivity to the conductive layer  104 . In other words, the etching process etches the insulating layer  102  with an etching rate faster than an etching rate to the conductive layer  104 , or etches none of the conductive layer  104  substantially. For example, the insulating layer  102  of oxide may be removed by using DHF, BOE, or other suitable etchants. In one embodiment, a pitch P 1  of the first openings  110  in a first direction  114  is bigger than a pitch P 2  of the first openings  110  in a second direction  116 , and the etching process is controlled (for example, by adjusting an etching time of an isotropic etching process) to removed a portion of specific size of the insulating layer  102 , so as to remain a portion  118  ( FIG. 2A  and  FIG. 2C ) of the insulating layer  102  between the first openings  110  in the first direction  114 , and communicate the first openings  110  in the second direction  116  (as shown in  FIG. 2A  and  FIG. 2B , thereby forming the second openings  112  separated from each other in the first direction  114  ( FIG. 2A  and  FIG. 2C ), and in a shape type that communicates the different first openings  110  in the second direction  116  at the same time ( FIG. 2A  and  FIG. 2B ). In embodiments, after the second openings  112  are formed, an insulating portion  120  ( FIG. 2A ) of the insulating layer  102  is remained between adjacent four of the first openings  110 . The insulating portion  120  can support the upper and lower conductive layers  104  to keep separating state from each other, and avoid an un-desired short circuit resulting from bending and collapsing of the conductive layers  104 . 
     Referring to  FIG. 3A  to  FIG. 3C , a dielectric layer  122  is formed to cover all of the conductive layers  104  and the insulating layers  102  exposed by the first openings  110  and the second openings  112 . The first openings  110  of the conductive layer  104  and the second openings  112  of the insulating layers  102  are filled with a conductive material (such as P+ polysilicon, N+ polysilicon, TiN, TaN, W, Ti, Cu, or other conformal conductors) to form conductive architectures  124  on the dielectric layer  122 . The conductive architecture  124  comprises first conductive portions  126  filling in the first openings  110 , and a second conductive portion  128  filling in the second opening  112  and connecting the first conductive portions  126 . The dielectric layer  122  and the conductive material on the hard mask  108  may be removed by a CMP process. The second conductive portion  128  is on and under the conductive layer  104 . In addition, the dielectric layer  122  electrically isolates the conductive layer  104  and the conductive architecture  124 , and electrically isolates the conductive architectures  124  from each other of different positions in the first direction  114 . 
     Referring to  FIG. 3B , the conductive architecture  124  surrounds upper and lower surfaces and opposing sidewalls of the conductive layer  104  between the first openings  110 . One of the second conductive portions  128  overlaps the first conductive portions  126  in the different first openings  110 . 
     Referring to  FIG. 4A  to  FIG. 4C , insulating plugs  130  are formed to pass through the conductive layers  104  and the insulating layers  102 , to electrically isolating the conductive architectures  124 . The insulating plugs  130  are formed by a method comprising defining third openings  132  in the conductive layers  104  and the insulating layers  102 , and filling a dielectric material (such as an oxide) into the third openings  132 . The dielectric material over the hard mask  108  may be removed by a CMP method. In one embodiment, the insulating plugs  130  are disposed between the first conductive portions  126  in the first direction  114 , and adjoined (physically contact) with at least the dielectric layer  122  on the first conductive portion  126  (or in the first opening  110 ), so as to, with the dielectric layer  122 , define a conductive strip  134  extending in the first direction  114  ( FIG. 4D , showing arrangements of the elements of the single level of the conductive layer  104 ) in the conductive layer  104 . In other embodiments, under the premise that electrical conduction of the conductive architecture  124  of different levels in a third direction  136  (vertical direction) is not influenced, the insulating plugs  130  may be further extended to touch the first conductive portions  126 . 
     In the embodiments, the semiconductor structure is a 3D stack memory array having the conductive strip  134  functioned as bit lines extending along the first direction  114 , and the conductive architectures  124  functioned as word lines extending along the second direction  116 . For example, the dielectric layer  122  between the conductive strip  134  and the conductive architectures  124  may be an ONO structure, an ONONO structure, an ONONONO structure, or a multi-layer structure of tunneling material/trapping material/blocking material structure applied to a storage material for NAND. For example, O1N1O2 is for tunneling material, N2 is for trapping material, O3 or O3/N3/O4 is for blocking material. In one embodiment, the semiconductor structure uses a tantalum-alumina-nitride-oxide-silicon (TANOS) structure, comprising a Si substrate, an OX/SiN/Al2O3 dielectric, and a TaN gate. 
     As shown in  FIG. 4B , the device has a gate-all-around (GAA) structure of the conductive architectures  124  (gate) surrounding the conductive strip  134  (bit line channel). This structure has a good gate-controlling ability and a high cell current, better than a double gate device or a single gate device. In addition, since the bit lines (the conductive strips  134 ) is surrounded by the gate, one of the bit lines would not be easily affected by another one of the bit lines during operating the device. Therefore, the coupling interference between the bit lines in Z direction would be reduced. 
     In some comparative examples, bit lines are formed a pattering method in which openings of long strip shape are defined in the conductive layers and the insulating layers. In other words, during the formation process, the whole of sidewalls of the bit lines are exposed to the openings, without being supported by other elements. However, in this condition, bending would easily occur to the bit lines of high aspect ratio due to other stress effect for example resulted from a solution filling in the openings, or dipping-in or pulling-out actions during a dip clean process. The bending damage would result in un-desired short circuit and reduce product yield. 
     In the embodiments of the present disclosure, the conductive strip  134  is formed by a method comprising pattering out the openings comprising the first openings  110  and the third openings  132 . During the formation process, the material for the conductive strip  134  is supported. Therefore, compared to the comparative example, embodiment has a stronger structure characteristic that would not easily have bending problem, and higher reliability. 
     Referring to  FIG. 5A  to  FIG. 5C , in some embodiments, conductive connections  138  such as word line connections extending in the second direction  116  and separated from each other on the conductive architectures  124 . Other elements such as contact structures and ILD (not shown) may be formed. 
     The present disclosure is not limited to the illustrations according to the above embodiment drawings, and can be adjusted according to actual demands and other suitable designs. 
     For example, in embodiments, a number of the first conductive portions  126  (or the first openings  110 ) of the single level of the conductive layer  104  is not limited to 4 of 2×2 (for defining the one conductive strip  134  extending in the first direction  114 ) as shown in figures, and may use other numbers higher than 4 properly. For example, 9×8 (equal to 64) of the first conductive portions  126  may be used for defining  8  the conductive strips  134  extending in the first direction  114  and electrically separated from each other by the dielectric layer  122  and more the insulating plugs  130 . For example, 9×16 (equal to 128) or other numbers of the first conductive portions  126  may be used. In the specific examples, one of 8 or 16 the second conductive portion  128  extending in the second direction  116  covers  9  the first conductive portions  126  at the same time, so as to form array device of more memory cells. 
     In some embodiments, the first openings  110  ( FIG. 1A ) may be designed as the pitch P 1  in the first direction  114  equal to the pitch P 2  in the second direction  116 , and therefore the second opening  112  formed by the etching process would be a continuous opening extending not only in the second direction  116  (as shown in  FIG. 2A ) but also in the first direction  114  (not shown). Although this figure would result in the conductive architectures  124  of a shape continuously extending both in the first direction  114  and the second direction  116  (not shown), the memory device can still be obtained since the insulating plugs  130  are formed to segment the conductive architectures  124  into parts electrically isolated from each other and define out the bit lines in the second direction  116 . In this case, the etching process for the second openings  112  is controlled to leave an insulating portion  120  (FIG.  2 A) of the insulating layer  102  between adjacent four of the first openings  110 . The insulating portion  120  can support the upper and lower conductive layers  104  to keep separating state from each other, and avoid an un-desired short circuit resulting from bending and collapsing of the conductive layers  104 . 
     The dielectric layer  122  may use multi-layer structure and a single layer structure. In embodiments, the dielectric elements may comprise an oxide, a nitride, an oxynitride, such as silicon oxide, silicon nitride, silicon oxynitride, or other suitable dielectric materials. The conductive elements may comprise polysilicon, a metal such as TiN, Ti, TaN, Ta, Au, W, etc., or other suitable conductive materials. 
     While the disclosure has been described by way of example and in terms of the exemplary embodiment(s), it is to be understood that the disclosure is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.