To increase read reliability margins in read-only MRAM arrays, a complimentary pair of MRAM cells includes a first MRAM cell having a first resistance value within a first high resistance range R.sub.H and storing a logic HI value and a second shorted MRAM cell having a second resistance value within a second minimal resistance range R.sub.o and storing a logic LO value. During manufacture and testing, MRAM cells that are assigned logic LO values are permanently shorted prior to distribution such that they permanently exhibit resistance values within the second minimal resistance range R.sub.o. When reading the values stored within the complimentary pair of MRAM cells, a differential sense amplifier applies a common reference current across the first MRAM cell and the second shorted MRAM cell; by shorting cells with logic LO values, a system can reliably read logic values stored within the read-only MRAM array.

A method for programming an electrically programmable fuse is disclosed. As conductive medium of the electrically programmable fuse exhibits different physical changes under different conditions, the conductive medium is changed from an initial physical state to a first physical state by using a first programming condition to program the electrically programmable fuse from a low resistance state to a medium resistance state, and the conductive medium is changed from the initial physical state or the first physical state to a second physical state by using a second programming condition to program the electrically programmable fuse from the low resistance state or the medium resistance state to a high resistance state. Transitions of three information storage states are achieved through two different programming conditions, so that the information storage density and chip area utilization rate of an electrically programmable fuse device can be significantly improved, and chip size reduction is facilitated.

The invention provides a multi-Vt vertical power device and a method of making the same. Through patterning a contact mask, a contact structure array having a shared trench gate structure may be formed, and different traversal gaps between an edge of a contact portion of a second conductivity type and an edge of a trench may be formed in the contact structure array. As such, multi-Vt vertical states may be implemented for storing information. The present invention allows making a multi-Vt vertical power device having different Vt's to be capable to store information without additional process steps. Therefore, with respect to the present invention, the process is simple, cost is low, and application field is wide; number of Vt varies to store multi-bit digital information or analog information in the power device; the built-in multi-Vt power MOSFET and IGBT are adapted not only for the high power applications but also for information storage.

A bi-sided pattern processor comprises a plurality of storage-processing units (SPU's). Each of the SPU's comprises at least a memory array and a pattern-processing circuit. The preferred pattern processor further comprises a semiconductor substrate with opposing first and second surfaces. The memory array is disposed on the first surface, whereas the pattern-processing circuit is disposed on the second surface. The memory array stores patterns; the pattern-processing circuit processes these patterns; and, they are communicatively coupled by a plurality of inter-surface connections.

A read-only memory (ROM) device includes memory cells, bit-line pairs, a virtual ground line, and a programmable metal track. The memory cells are arranged in an array of rows and columns. Each memory cell stores two bits of data. The virtual ground line is disposed vertically and shared by two adjacent columns. The programmable metal track connects a memory cell to the virtual ground line based on a value of the two bits of data stored in the memory cell.

A read-only memory (ROM) device includes memory cells, bit-line pairs, a virtual ground line, and a programmable metal track. The memory cells are arranged in an array of rows and columns. Each memory cell stores two bits of data. The virtual ground line is disposed vertically and shared by two adjacent columns. The programmable metal track connects a memory cell to the virtual ground line based on a value of the two bits of data stored in the memory cell.

To reduce the pre-programming cost, an efficient three-dimensional one-time-programmable read-only memory (3D-OTP) is disclosed. It comprises a dummy word line and a plurality of dummy bit lines. Only the dummy OTP cells at the intersections of the dummy word line and dummy bit lines are programmed. All other dummy OTP cells are unprogrammed.

To reduce the pre-programming cost, a double-biased three-dimensional one-time-programmable read-only memory (3D-OTP) is disclosed. The OTP array comprises a dummy word line and a plurality of data word lines. During read, both voltages on the dummy word line and a selected data word line are raised.

A mask read only memory device is provided. Single-transistor memory cells are arranged in rows and columns. Each word line is associated with a corresponding row. Each bit line is associated with a corresponding column. Each first reference line selectively provides a first potential in a first phase and a second potential in a second phase. Each second reference line selectively provides the second potential in the first read phase and the first potential in the second phase. Each memory cell has a gate coupled to a word line, a drain coupled to a bit line and a source terminal either floating, grounded or coupled to one among a first reference line and a second reference line. One of first to fourth logic values is read during a read operation of the memory cell.

The present invention discloses a multi-bit-per-cell three-dimensional read-only memory (3D-OTP.sub.MB) comprising a plurality of dummy bit lines. It comprises a plurality of OTP cells stacked above a semiconductor substrate. Each OTP array comprises at least four dummy bit lines.