Patents Assigned to SanDisk Corporation
  • Patent number: 7965562
    Abstract: In a nonvolatile memory having an array of memory cells, wherein the memory cells are individually programmable to one of a range of threshold voltage levels, there is provided a predictive programming mode in which a predetermined function predicts what programming voltage level needs to be applied in order to program a given memory cell to a given target threshold voltage level. In this way, no verify operation needs to be performed, thereby greatly improving the performance of the programming operation. In a preferred embodiment, the predetermined function is linear and is calibrated for each memory cell under programming by one or more checkpoints. The checkpoint is an actual programming voltage that programs the memory cell in question to a verified designated threshold voltage level.
    Type: Grant
    Filed: December 29, 2009
    Date of Patent: June 21, 2011
    Assignee: Sandisk Corporation
    Inventor: Raul-Adrian Cernea
  • Patent number: 7965560
    Abstract: A non-volatile memory device capable of reading and writing a large number of memory cells with multiple read/write circuits in parallel has features to reduce power consumption during sensing, which is included in read, and program/verify operations. A sensing verify operation includes one or more sensing cycles relative to one or more demarcation threshold voltages to determine a memory state. In one aspect, coupling of the memory cells to their bit lines are delayed during a precharge operation in order to reduced the cells' currents working against the precharge. In another aspect, a power-consuming precharge period is minimized by preemptively starting the sensing in a multi-pass sensing operation. High current cells not detected as a result of the premature sensing will be detected in a subsequent pass.
    Type: Grant
    Filed: April 20, 2010
    Date of Patent: June 21, 2011
    Assignee: Sandisk Corporation
    Inventors: Shou-Chang Tsao, Yan Li
  • Publication number: 20110141816
    Abstract: Tracking cells are used in a memory system to improve the read process. The tracking cells can provide an indication of the quality of the data and can be used as part of a data recovery operation if there is an error. The tracking cells provide a means to adjust the read parameters to optimum levels in order to reflect the current conditions of the memory system. Read operations are performed on the tracking cells, where threshold voltages of physical states of the tracking cells are further apart than threshold voltages of physical states of non-tracking cells. Based on the read operations, an extent to which the tracking cells are errored is determined.
    Type: Application
    Filed: February 18, 2011
    Publication date: June 16, 2011
    Applicant: SANDISK CORPORATION
    Inventors: Daniel C. Guterman, Stephen J. Gross, Shahzad Khalid, Geoffrey S. Gongwer
  • Patent number: 7962819
    Abstract: An integrated circuit chip includes a scan-in pin, a scan clock pin, and a test controller. The scan-in pin and the scan clock pin receive a test program for the type of test mode and a soft-reset pattern. A state machine is configured to direct sampling of a scan clock waveform provided through the scan clock pin as dictated by transitions of a scan-in waveform provided through the scan-in pin. The state machine identifies a bit match from the sampled scan clock waveform upon executing the soft-reset pattern. The identified bit match triggers a soft reset which eliminates the need for an extra reset pin, when testing in scan mode.
    Type: Grant
    Filed: January 24, 2008
    Date of Patent: June 14, 2011
    Assignee: SanDisk Corporation
    Inventors: Baojing Liu, Matt Davidson, Vladimir Kovalev
  • Patent number: 7961511
    Abstract: A hybrid method of programming a non-volatile memory cell to a final programmed state is described. The method described is a more robust protocol suitable for reliably programming selected memory cells while eliminating programming disturbs. The hybrid method comprises programming the non-volatile memory cell to a first state according to a first coarse programming mechanism, and programming the non-volatile memory cell according to a second different more precise programming mechanism thereby completing the programming of the non-volatile memory cell to the final programmed state. Additionally, the described method is particularly advantageous for programming multilevel chips.
    Type: Grant
    Filed: September 26, 2006
    Date of Patent: June 14, 2011
    Assignee: SanDisk Corporation
    Inventors: Dana Lee, Yingda Dong, Changyuan Chen, Jeffrey Lutze
  • Patent number: 7962682
    Abstract: Methods and apparatus for accessing modules on a flash memory package concurrently during testing are disclosed. According to one aspect of the present invention, a memory device for storing data includes a plurality of modules and a logic block. The plurality of modules each include a plurality of storage elements that hold the data. The logic block is arranged to enable the plurality of modules to be accessed in parallel, and is also arranged to enable the plurality of modules to be accessed serially.
    Type: Grant
    Filed: October 23, 2006
    Date of Patent: June 14, 2011
    Assignee: SanDisk Corporation
    Inventor: Jason T. Lin
  • Patent number: 7961512
    Abstract: A non-volatile memory can perform a first operation (such as a write, for example) on a designated group of one or more addressed pages using a first set of data stored in the corresponding set of data latches and also receive a request for a second operation (such as a read, for example) that also uses some of these corresponding data latches with a second set of data. During the first operation, when at least one latch of each set of the corresponding become available for the second operation, the memory whether there are a sufficient number of the corresponding set of data latches to perform the second operation during the first operation; if not, the second operation is delayed.
    Type: Grant
    Filed: March 19, 2008
    Date of Patent: June 14, 2011
    Assignee: SanDisk Corporation
    Inventors: Yan Li, Anne Pao-Ling Koh
  • Patent number: 7960266
    Abstract: High density semiconductor devices and methods of fabricating the same are provided. Spacer fabrication techniques are utilized to form circuit elements having reduced feature sizes, which in some instances are smaller than the smallest lithographically resolvable element size of the process being used. Spacers are formed that serve as a mask for etching one or more layers beneath the spacers. An etch stop pad layer having a material composition substantially similar to the spacer material is provided between a dielectric layer and an insulating sacrificial layer such as silicon nitride. When etching the sacrificial layer, the matched pad layer provides an etch stop to avoid damaging and reducing the size of the dielectric layer. The matched material compositions further provide improved adhesion for the spacers, thereby improving the rigidity and integrity of the spacers.
    Type: Grant
    Filed: June 1, 2010
    Date of Patent: June 14, 2011
    Assignee: SanDisk Corporation
    Inventors: James Kai, George Matamis, Tuan Duc Pham, Masaaki Higashitani, Takashi Orimoto
  • Patent number: 7962777
    Abstract: Multiple copies of firmware code for controlling operation of a non-volatile flash memory system are stored at different suitable locations of the flash memory of a memory system. A map of addresses of these locations is also stored in the flash memory. Upon initialization of the memory system, boot code stored in the memory controller is executed by its microprocessor to reference the address map and load one copy of the firmware from the flash memory into a controller memory, from which it may then be executed by the microprocessor to operate the memory system to store and retrieve user data. An error correction code (ECC) is used to check the data but the best portions of the two or more firmware copies stored in the flash memory are used to reduce the need to use ECC. The firmware code may be stored in the flash memory in two-states when user data is stored in the same memory in more than two-states.
    Type: Grant
    Filed: June 15, 2009
    Date of Patent: June 14, 2011
    Assignee: Sandisk Corporation
    Inventors: Carlos J. Gonzalez, Andrew Tomlin
  • Patent number: 7962684
    Abstract: The operating firmware of a portable flash memory storage device is stored in the relatively large file storage memory, which is non executable. It is logically parsed into overlays to fit into an executable memory. The overlays can be of differing sizes to organize function calls efficiently while minimizing dead space or unnecessarily separating functions that should be within one or a group of frequently accessed overlays. Eviction of the overlays is preferably carried out on a least recently loaded basis. These features minimize latency caused by calling overlays unnecessarily and minimize fragmentation of the random access memory used for the overlays.
    Type: Grant
    Filed: February 14, 2008
    Date of Patent: June 14, 2011
    Assignee: Sandisk Corporation
    Inventors: Vadzim Struk, Aleh Dzenisiuk, Derrill Sturgeon
  • Publication number: 20110134694
    Abstract: Non-volatile memory is programmed using source side hot electron injection. To generate a high voltage bit line for programming, the bit line corresponding to a selected memory cell is charged to a first level using a first low voltage. A second low voltage is applied to unselected bit lines adjacent to the selected bit line after charging. Because of capacitive coupling between the adjacent bit lines and the selected bit line, the selected bit line is boosted above the first voltage level by application of the second low voltage to the unselected bit lines. The column control circuitry for such a memory array does not directly apply the high voltage and thus, can be designed to withstand lower operating voltages, permitting low operating voltage circuitry to be used.
    Type: Application
    Filed: February 16, 2011
    Publication date: June 9, 2011
    Applicant: SanDisk Corporation
    Inventors: Dana Lee, Hock So
  • Patent number: 7957197
    Abstract: Sensing circuits for sensing a conduction current of a memory cell among a group of non-volatile memory cells being sensed in parallel and providing the result of the sensing to a data bus are presented. A precharge circuit is coupled to a node for charging the node to an initial voltage. An intermediate circuit is also coupled to the node and connectable to the memory cell, by which current from the precharge circuit can be supplied to the memory cell. The circuit also includes a comparator circuit to perform a determination of the conduction current by a rate of discharge at the node; a data latch coupled to the comparator circuit to hold the result of this determination; and a transfer gate coupled to the data latch to supply a latched result to the data bus independently of the node. This arrangement improves sensing performance and can help to eliminate noise on the analog sensing path during sensing and reduce switching current.
    Type: Grant
    Filed: May 28, 2008
    Date of Patent: June 7, 2011
    Assignee: SanDisk Corporation
    Inventors: Hao Thai Nguyen, Man Lung Mui, Seungpil Lee, Fanglin Zhang, Chi-Ming Wang
  • Patent number: 7958390
    Abstract: A memory device for repairing a neighborhood of rows in a memory array using a patch table is disclosed. In one embodiment, circuitry in the memory device is operative to store, in a temporary storage area of the memory device, (i) first data to be stored in row N in the memory array, (ii) second data, if any, stored in row N?1 in the memory array, and (iii) third data, if any, stored in row N+1 in the memory array. The circuitry is operative to write the first data in row N in the memory array, and, in response to an error in writing the first data, to write the first data, the second data, if any, and the third data, if any, in respective rows in a repair area in the memory device. The circuitry is further operative to add the addresses of rows N?1, N, and N+1 to a table stored in the memory device.
    Type: Grant
    Filed: May 15, 2007
    Date of Patent: June 7, 2011
    Assignee: SanDisk Corporation
    Inventors: Derek J. Bosch, Christopher S. Moore
  • Patent number: 7957187
    Abstract: A process is performed periodically or in response to an error in order to dynamically and adaptively optimize read compare levels based on memory cell threshold voltage distribution. One embodiment of the process includes determining threshold voltage distribution data for a population of non-volatile storage elements, smoothing the threshold voltage distribution data using a weighting function to create an interim set of data, determining a derivative of the interim set of data, and identifying and storing negative to positive zero crossings of the derivative as read compare points.
    Type: Grant
    Filed: December 18, 2008
    Date of Patent: June 7, 2011
    Assignee: Sandisk Corporation
    Inventors: Nima Mokhlesi, Henry Chin
  • Patent number: 7957185
    Abstract: A non-volatile memory device capable of reading and writing a large number of memory cells with multiple read/write circuits in parallel has features to reduce power consumption during read, and program/verify operations. A read or program verify operation includes one or more sensing cycles relative to one or more demarcation threshold voltages to determine a memory state. In one aspect, selective memory cells among the group being sensed in parallel have their conduction currents turned off when they are determined to be in a state not relevant to the current sensing cycle. In another aspect, a power-consuming period is minimized by preemptively starting any operations that would prolong the period. In a program/verify operation cells not to be programmed have their bit lines charged up in the program phase. Power is saved when a set of these bit lines avoids re-charging at every passing of a program phase.
    Type: Grant
    Filed: September 22, 2006
    Date of Patent: June 7, 2011
    Assignee: Sandisk Corporation
    Inventors: Yan Li, Seungpil Lee, Siu Lung Chan
  • Publication number: 20110131473
    Abstract: Data stored in non-volatile storage is decoded using iterative probabilistic decoding and multiple read operations to achieve greater reliability. An error correcting code such as a low density parity check code may be used. In one approach, initial reliability metrics, such as logarithmic likelihood ratios, are used in decoding read data of a set of non-volatile storage element. The decoding attempts to converge by adjusting the reliability metrics for bits in code words which represent the sensed state. If convergence does not occur, e.g., within a set time period, the state of the non-volatile storage element is sensed again, current values of the reliability metrics in the decoder are adjusted, and the decoding again attempts to converge.
    Type: Application
    Filed: February 10, 2011
    Publication date: June 2, 2011
    Applicant: SANDISK CORPORATION
    Inventors: Nima Mokhlesi, Henry Chin, Dengtao Zhao
  • Patent number: 7951669
    Abstract: Methods of fabricating a dual control gate non-volatile memory array are described. Parallel strips of floating gate material are formed over the substrate in a first direction but separated from it by a tunnel dielectric. In the gaps between these strips control gate material is formed forming a second set of parallel strips but insulated from both the adjacent floating gate stripes and the substrate. Both sets of strips are isolated in a second direction perpendicular to the first direction forming an array of individual floating gates and control gates. The control gates formed from an individual control gate strip are then interconnected by a conductive wordline such the potential on individual floating gates are controlled by the voltages on two adjacent wordlines. In other variations either the floating gates or the control gates may be recessed into the original substrate.
    Type: Grant
    Filed: April 13, 2006
    Date of Patent: May 31, 2011
    Assignee: SanDisk Corporation
    Inventors: Eliyahou Harari, George Samachisa
  • Patent number: 7952179
    Abstract: A portable memory card and methods of manufacturing same are disclosed. The portable memory includes a substrate having a plurality of holes formed therein. During the encapsulation process, mold compound flows over the top surface of the substrate, through the holes, and down into a recessed section formed in the bottom mold cap plate to form a projection of mold compound on the bottom surface of the substrate.
    Type: Grant
    Filed: June 28, 2007
    Date of Patent: May 31, 2011
    Assignee: SanDisk Corporation
    Inventors: Chin-Tien Chiu, Hem Takiar, Chih-Chin Liao, Cheemen Yu, Ning Ye, Jack Chang Chien
  • Patent number: 7952925
    Abstract: A nonvolatile semiconductor memory device includes a memory cell array constituted by a plurality of memory blocks, an interface, a write circuit, and a read circuit. A protect flag is written in the memory block. The readout protect flag can be output to an external device through the interface. When a write command is input from the interface, the write circuit executes the write command when the protect flag in the selected memory block has a first value and does not execute the write command when the protect flag has a second value.
    Type: Grant
    Filed: July 29, 2010
    Date of Patent: May 31, 2011
    Assignees: Kabushiki Kaisha Toshiba, SanDisk Corporation
    Inventors: Tomoharu Tanaka, Koichi Kawai, Khandker N Quader
  • Patent number: 7953930
    Abstract: A memory card has a data scrambler that performs a data scrambling operation on data stored in the memory card according to a device ID associated with the memory card. The device ID is either set at the factory and permanently stored in the card, or configurable by a user or a host system.
    Type: Grant
    Filed: December 7, 2007
    Date of Patent: May 31, 2011
    Assignee: SanDisk Corporation
    Inventor: Steven S. Cheng