摘要:
A stress mode for use in testing non-volatile memory arrays for a number of types of defects is described. More specifically, a multi-word line select option for a given block can be used for a group of selected word lines to be set to the a programming or other high voltage, while the unselected word lines of the block are set to a pass voltage to minimize electric field differences in order to avoid disturb. For example, a group of selected word lines could number 4, 8 or 16. The multi-word line option can be applied to one block per plane, so that if there are two memory planes, for example, two such blocks can be selected simultaneously for the multi-word line option for those blocks.
摘要:
Techniques are presented for the determination and handling of defects in non-volatile arrays, particularly those having a 3D or BiCS type of arrangement where NAND strings run in a vertical direction relative to the substrate. In such an arrangement, the NAND strings are formed along memory holes and connected to global bit lines, and are separated into blocks or sub-blocks by vertical local interconnects, such as for source lines, and connected to a corresponding global line. To determine defects, an AC stress can be applied between the interconnects and the bit lines/NAND strings, after which a defect determination operation can be performed. This technique can also be implemented at the system level by having the controller instruct the memory to perform it as part of an adaptive defect determination operation.
摘要:
Detecting defects in select gates of memory cell strings is disclosed. An electrical short between adjacent select gates may be detected. The select gate may comprises a transistor having an adjustable threshold voltage. An operation configured to change a threshold voltage of one select transistor and to maintain a threshold voltage of an adjacent select transistor may be performed. The select transistors may be flagged in response to the threshold voltage of either select transistor failing to meet a target threshold voltage in response to the operation. The operation may be an erase operation or a program operation.
摘要:
A stress mode for use in testing non-volatile memory arrays for a number of types of defects is described. More specifically, a multi-word line select option for a given block can be used for a group of selected word lines to be set to the a programming or other high voltage, while the unselected word lines of the block are set to a pass voltage to minimize electric field differences in order to avoid disturb. For example, a group of selected word lines could number 4, 8 or 16. The multi-word line option can be applied to one block per plane, so that if there are two memory planes, for example, two such blocks can be selected simultaneously for the multi-word line option for those blocks.
摘要:
For a non-volatile memory device having a NAND type of architecture, techniques are presented for determining NAND strings that are slow to program. These techniques are particularly applicable to memory devices have a 3D structure, such as of BiCS type, where the slow programming can arise from defects of the spacing between the memory holes, in which the NAND strings are formed, and the local interconnects, such as for connecting common source lines and which run in a vertical direction between groups of NAND strings. The slow to program NAND strings can be recorded and this information can be used when writing data to the NAND strings. Several methods of writing data along a word line that includes such slow to program cells are described.
摘要:
A number of techniques for determining bit line related defects in non-volatile memory arrays are presented, which are particularly applicable to 3D NAND memory, such as that of the BiCS type. Defects related to bit line to NAND string contacts are determined by application of an AC stress mode along bit lines, followed by a defect detection operation. If the AC stress is applied to be out of phase on adjacent bit lines, this can also be used to accelerate bit line to bit line defects. The subsequent defect determination phase can include an erase operation followed a read to determine whether the NAND strings of the erased block read as erased, a process that can also be followed by a program and subsequent read to further check for defects.
摘要:
A non-volatile storage system includes a three dimensional structure comprising vertical columns of memory cells and a managing circuit in communication with the vertical columns. The managing circuit applies one or more patterns of stress voltages to the vertical columns, with different voltages applied to each vertical column of pairs of adjacent vertical columns being tested for shorts. The managing circuit tests for a short in the pairs of adjacent vertical columns after applying the one or more patterns of stress voltages. In one embodiment, the test may comprise programming a memory cell in each vertical column with data that matches the pattern of stress voltages, reading from the memory cells and determining whether data read matches data programmed. The applying of the stress voltages and the testing can be performed as part of a test during manufacturing or in the field during user operation.
摘要:
Techniques are provided for operating a memory device which detect word line short circuits, such as short circuits between adjacent word lines. In an example implementation, during a programming operation, the number of program loops used to complete programming or reach another programming milestone for WLn are counted. If the number of program loops exceeds a loop count limit, the memory cells of WLn+1 are evaluated to determine whether a short circuit is present. The evaluation involves a read operation which counts erased state memory cells in the upper tail of the Vth distribution of WLn+1. If the count exceeds a bit count limit, it is concluded that a short circuit exits between WLn and WLn+1, and a corrective action is taken. The loop count limit is adjusted lower as the number of program-erase cycles increases.
摘要:
A number of techniques for determining defects in non-volatile memory arrays are presented, which are particularly applicable to 3D NAND memory, such as that of the BiCS type. Word line to word shorts within a memory block are determined by application of an AC stress mode, followed by a defect detection operation. An inter-block stress and detection operation can be used determine word line to word line leaks between different blocks. Select gate leak line leakage, both the word lines and other select lines, is consider, as are shorts from word lines and select lines to local source lines. In addition to word line and select line defects, techniques for determining shorts between bit lines and low voltage circuitry, as in the sense amplifiers, are presented.
摘要:
A number of techniques for determining defects in non-volatile memory arrays are presented, which are particularly applicable to 3D NAND memory, such as that of the BiCS type. Word line to word shorts within a memory block are determined by application of an AC stress mode, followed by a defect detection operation. An inter-block stress and detection operation can be used determine word line to word line leaks between different blocks. Select gate leak line leakage, both the word lines and other select lines, is consider, as are shorts from word lines and select lines to local source lines. In addition to word line and select line defects, techniques for determining shorts between bit lines and low voltage circuitry, as in the sense amplifiers, are presented.