HIGH RELIABILITY OTP MEMORY
First Claim
1. A method for programming one time programmable (OTP) memory cells comprising:
- i) programming input data with first programming parameters;
ii) identifying bits of the input data which failed programming with the first programming parameters as failed bits;
iii) reprogramming the failed bits with second programming parameters different from the first programming parameters; and
,iv) repeating the method at ii) if at least one bit is identified as failing the reprogramming.
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Accused Products
Abstract
A method and system for improving reliability of OTP memories, and in particular anti-fuse memories, by storing one bit of data in at least two OTP memory cells. Therefore each bit of data is read out by accessing the at least two OTP memory cells at the same time in a multi-cell per bit mode. By storing one bit of data in at least two OTP memory cells, defective cells or weakly programmable cells are compensated for since the additional cell or cells provide inherent redundancy. Program reliability is ensured by programming the data one bit at a time, and verifying all programmed bits in a single-ended read mode, prior to normal operation where the data is read out in the multi-cell per bit mode. Programming and verification is achieved at high speed and with minimal power consumption using a novel program/verify algorithm for anti-fuse memory. In addition to improved reliability, read margin and read speed are improved over single cell per bit memories.
45 Citations
37 Claims
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1. A method for programming one time programmable (OTP) memory cells comprising:
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i) programming input data with first programming parameters; ii) identifying bits of the input data which failed programming with the first programming parameters as failed bits; iii) reprogramming the failed bits with second programming parameters different from the first programming parameters; and
,iv) repeating the method at ii) if at least one bit is identified as failing the reprogramming. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A one time programmable memory system, comprising:
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a memory array having one time programmable (OTP) cells connected to bitlines and wordlines; a select circuit configurable to couple a variable number of OTP cells to a sense amplifier at the same time in response to an address and a selected read mode of operation; and
,a mode selector for selecting the read mode of operation to control the select circuit to access one OTP cell per bit of data in a single-ended mode during a program or verify operation, and to control the select circuit to concurrently access at least two OTP cells per bit of data for sensing during a read operation. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification