Abstract:
The present invention discloses a hybrid content-distribution system. It uses two types of memory to distribute contents: re-writable memory (RWM) and three-dimensional mask-programmed read-only memory (3D-MPROM). During a publication period, new contents are transferred from a remote server to the RWM. At the end of the publication period, a user receives a 3D-MPROM, which stores a collection of the transferred contents. To make room for the contents to be released during the next publication period, the contents common to the 3D-MPROM and the RWM are deleted from the RWM afterwards.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application relates to a provisional application, “Content-Delivery System and Method Using Three-Dimensional Printed Memory”, Application Ser. No. 61/529,925, filed Sep. 1, 2011. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field of the Invention 
         [0003]    The present invention relates to the field of integrated circuit, more particularly to mask-programmed read-only memory (mask-ROM). 
         [0004]    2. Prior Arts 
         [0005]    With the advent of three-dimensional mask-programmed read-only memory (3D-MPROM), the storage capacity of the mask-ROM greatly improves. 3D-MPROM is primarily used for mass publication, i.e. mass distribution of mass contents. U.S. Pat. No. 5,835,396 discloses a 3D-MPROM. It is a monolithic semiconductor memory. As illustrated in  FIG. 1 , a typical 3D-MPROM comprises a semiconductor substrate  0  and a 3-D stack  10  stacked above. The 3-D stack  10  comprises M (M≧2) vertically stacked memory levels (e.g.  10 A,  10 B). Each memory level (e.g.  10 A) comprises a plurality of upper address lines (e.g.  2   a ), lower address lines (e.g.  1   a ) and memory cells (e.g.  5   aa ). Each memory cell stores n (n≧1) bits. Memory levels (e.g.  10 A,  10 B) are coupled to the substrate  0  through contact vias (e.g.  1   av,    1   av ′). The substrate circuit OX in the substrate  0  comprises a peripheral circuit for the 3-D stack  10 . Hereinafter, xM×n 3D-MPROM denotes a 3D-MPROM comprising M memory levels with n bits-per-cell (bpc). 
         [0006]    3D-MPROM is a diode-based cross-point memory. Each memory cell (e.g.  5   aa ) typically comprises a diode  3   d.  The diode can be broadly interpreted as any device whose electrical resistance at the read voltage is lower than that when the applied voltage has a magnitude smaller than or polarity opposite to that of the read voltage. The memory level  10 A further comprises a data-coding layer  6 A, i.e. a blocking dielectric  3   b.  It blocks the current flow between the upper and lower address lines. Absence or existence of a data-opening  6   ca  in the blocking dielectric  3   b  indicates the state of a memory cell. Besides the blocking dielectric  3   b,  the data-coding layer  6 A could also comprise a resistive layer (referring to U.S. patent application Ser. No. 12/785,621) or an extra-dopant layer (referring to U.S. Pat. No. 7,821,080). 
         [0007]    Because the prior-art mask-ROM has a limited storage capacity, when it is used for content distribution, a separate new mask-ROM card is issued for each newly released content.  FIG. 2  illustrates an example. Contents C 1  (e.g. movie  1 ), C 2  (e.g. movie  2 ), . . . are released at time t 1 , t 2 , . . . , respectively. A separate mask-ROM card is issued for each new content: at time t 1 , a first mask-ROM card m 1 , which stores the content C 1 , is delivered to a user; at time t 2 , a second mask-ROM card m 2 , which stores the content C 2 , is delivered to the user; . . . . As more and more contents are released, this content-distribution method becomes cumbersome, because the user needs to manage hundreds, even thousands of mask-ROM cards. 
       OBJECTS AND ADVANTAGES 
       [0008]    It is a principle object of the present invention to provide a content-distribution system that makes memory-card management easier for a user. 
         [0009]    It is a further object of the present invention to provide a content-distribution method that offers a user timely access to the new contents. 
         [0010]    It is a further object of the present invention to provide a content-distribution method that keeps the cost of the content storage low. 
         [0011]    In accordance with these and other objects of the present invention, hybrid content-distribution system and method are disclosed. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention discloses a hybrid content-distribution system. It comprises a playback device (e.g. cellular phone, internet TV, or computer) and uses two types of memory to distribute contents: re-writable memory (RWM) and 3D-MPROM. The RWM is part of the playback device, while the 3D-MPROMs are periodically delivered to a user. 
         [0013]    Hybrid content-distribution takes advantage of the fact that the 3D-MPROM is much less expensive than the RWM and stores the past contents in the 3D-MPROM. It also takes advantage of the fact that the RWM is re-writable and stores the new contents in the RWM. During a publication period, new contents, once released, are transferred from a remote server to the playback device and saved into the RWM. At the end of the publication period, a user receives a 3D-MPROM card which stores a collection of the transferred contents. To make room for the contents to be released during the next publication period, the contents common to the 3D-MPROM and the RWM are deleted from the RWM. Hybrid content-distribution offers the user timely access to the new contents while keeping the overall storage cost low. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a cross-sectional view of a 3D-MPROM; 
           [0015]      FIG. 2  discloses a content-distribution method from prior arts; 
           [0016]      FIG. 3  is a block diagram of a preferred hybrid content-distribution system and its communication with a remote server; 
           [0017]      FIGS. 4A-4B  illustrate two preferred playback devices; 
           [0018]      FIG. 5  is a flow chart for a preferred hybrid content-distribution method; 
           [0019]      FIG. 6  illustrates the amount of the occupied space in the RWM at different time points; 
           [0020]      FIGS. 7A-7B  are cross-sectional views of a preferred 3D-MPROM cartridge at different time points T 1 , T 2 . 
       
    
    
       [0021]    It should be noted that all the drawings are schematic and not drawn to scale. Relative dimensions and proportions of parts of the device structures in the figures have been shown exaggerated or reduced in size for the sake of clarity and convenience in the drawings. The same reference symbols are generally used to refer to corresponding or similar features in the different embodiments. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    Those of ordinary skills in the art will realize that the following description of the present invention is illustrative only and is not intended to be in any way limiting. Other embodiments of the invention will readily suggest themselves to such skilled persons from an examination of the within disclosure. 
         [0023]    The present invention uses 3D-MPROM as an example to explain the concept of hybrid content-distribution. The preferred embodiments disclosed herein can be extended to any large-capacity mask-ROM. A large-capacity mask-ROM has a storage capacity on the order of GB, even on the order of TB. In the present invention, the primary data-recording means for a mask-ROM includes photo-lithography and imprint-lithography. The “mask” in the mask-ROM includes data-mask used in photo-lithography, as well as nano-imprint mold or nano-imprint template used in imprint-lithography. 
         [0024]    Referring now to  FIG. 3 , a preferred hybrid content-distribution system  40  and its communication channel  50  with a remote server  100  are disclosed. It comprises a memory card  20  and a playback device  30 . The memory card  20  could comprise a memory package or a memory module. It contains at least one 3D-MPROM die, more generally, at least one large-capacity mask-ROM die. The memory card  20  stores contents such as movies, video games, maps, music library, book library, and/or softwares. 
         [0025]    The playback device  30 , more generally, a consumer processing apparatus, can read and process data from the memory card  20 , e.g. playing a movie or video game, reading a map, listening to music, reading books, or running software. The playback device  30  comprises a communicating means  36  and a re-writable memory (RWM)  48 . The communicating means  36  communicates with a remote server  100  through a communication channel  50 . The remote server  100  stores a mass-content library. The communication channel  50  includes internet, WiFi and cellular (e.g. 3G, 4G) signals. The RWM  48  is a non-volatile re-writable memory, e.g. a flash memory. 
         [0026]      FIG. 4A  illustrates a preferred playback device  30 —a cellular phone. It communicates with the remote server  100  via cellular signals  50 . The cellular phone  30  further comprises a slot  32  for holding the memory card  20 , which can be inserted into or removed from the cellular phone  30 .  FIG. 4B  illustrates another preferred playback device  30 —an internet TV (or, a computer). It communicates with the remote server  100  via internet signals (including wired and wireless internet signals)  50 . The internet TV (or, computer)  30  further comprises a slot  32  for holding the memory card  20 , which can be inserted into or removed from the internet TV (or, computer)  30 . 
         [0027]    The present invention discloses a hybrid content-distribution method. It takes advantage of the fact that the 3D-MPROM is much less expensive than the RWM and stores the past contents in the 3D-MPROM. It also takes advantage of the fact that the RWM is re-writable and stores the new contents in the RWM.  FIG. 5  discloses a preferred hybrid content-distribution method; and  FIG. 6  illustrates the amount of the occupied space in the RWM  48  at different time points. 
         [0028]    The preferred hybrid content-distribution method includes a number of publication periods (e.g. PERIOD  1  and PERIOD  2 ). Each publication period comprises similar steps. During PEORID  1  (e.g. during the first two months), new contents (i.e. the contents released during the current publication period), once released, are transferred from the remote server  100  to the playback device  30 . For example, content C 1  (e.g. movie  1 ) is transferred at time t 1  (step  701 ); content C 2  (e.g. movie  2 ) is transferred at time t 2  (step  702 ); . . . ; content C n  (e.g. movie n) is transferred at time t n  (step  70   n ). Here, new contents are either downloaded by the playback device  30  or pushed in by the remote server  100 . The transferred contents are stored in the RWM  48 . This is reflected by the staircase RWM curve between t 1  and T 1  of  FIG. 6 . During PERIOD  1 , the contents C 1 , C 2 , . . . C n  are accessed from the RWM  48 . 
         [0029]    At the end of PERIOD  1 , a first set of contents S 1  (=C 1 +C 2 + . . . +C n ) is accumulated in the RWM  48 . At time T 1 , a user receives a first memory card M 1  (step  76 ), which permanently stores the first set of contents S 1 . Afterwards, the first set of contents S 1  is deleted from the RWM  48  (step  84 ). This is reflected by the steep drop of the RWM curve at T 1  in  FIG. 6 . Because the RWM  48  is emptied, PERIOD  2  can now start. After PERIOD  1 , the contents C 1 , C 2 , . . . C n  can be accessed from the memory card M 1 . 
         [0030]    During PERIOD  2  (e.g. during the next two months), similar steps (steps  70   1 - 84 ) are performed. Contents C n+1 , C n+2 , . . . C m  are transferred at time t n+1 , t n+2 , . . . t m , respectively. During this period, the contents C n+1 , C n+2 , . . . C m  are accessed from the RWM  48 . At the end of PERIOD  2 , a second set of contents S 2  (=C n +1 +C n+2 + . . . +C m ) is accumulated in the RWM  48 . At time T 2 , the user receives a second memory card M 2 , which permanently stores the second set of contents S 2 . Then the second set of contents S 2  is deleted from the RWM  48 . After PERIOD  2 , the contents C n+1 , C n+2 , . . . C m  are accessed from the second memory card M 2 . 
         [0031]    Because the playback device  30  can communicate with the remote server  100  in a timely manner, the preferred hybrid content-distribution method offers the user timely access to the new contents. Moreover, because the past contents (i.e. contents released during the previous publication periods) are stored in the memory cards (e.g. M 1 , M 2 , . . . ) and only the new contents need to be stored in the RWM  48 , the playback device  30  only needs a limited amount of the RWM  48 . Since the 3D-MPROM is much less expensive than the RWM, the overall storage cost for this hybrid content-distribution method is much lower than prior arts where all contents are stored in the RWM. 
         [0032]    The present invention further discloses a preferred 3D-MPROM cartridge  90  that can accommodate hybrid content-distribution.  FIGS. 7A-7B  illustrate its configurations at different time points T 1 , T 2 . The 3D-MPROM cartridge  90  comprises a cartridge frame  99 , which comprises a plurality of slots (e.g.  90 B,  90 C) for holding the memory cards. At T 1 , a memory card  20 A, which comprises two vertically stacked 3D-MPROM dice  10 A,  10 B, is released. It is inserted into the bottom slot of the memory cartridge  90 . At this time, the slots  90 B,  90 C are empty. At T 2 , the memory card  20 B, which comprises two vertically stacked 3D-MPROM dice  10 C,  10 D, is released. It is then inserted into the slot  90 B. At this time, the slot  90 C is empty. The cartridge frame  99  can provide electrical connections between the memory cards  20 A and  20 B (not shown in this figure). Preferably, the playback device  30  can directly read data from the 3D-MPROM cartridge  90 . Apparently, the preferred memory cartridge  90  can have more than three slots. For example, it may comprise six slots. Assuming a new memory card is released every two month, a single memory cartridge can hold all memory cards released in a year. The memory cartridge  90  makes the memory-card management much easier. 
         [0033]    While illustrative embodiments have been shown and described, it would be apparent to those skilled in the art that may more modifications than that have been mentioned above are possible without departing from the inventive concepts set forth therein. Besides 3D-MPROM, the field-repair system and method disclosed herein can be extended to other mask-ROMs. The invention, therefore, is not to be limited except in the spirit of the appended claims.