Nonvolatile memory, semiconductor device, and method of programming to nonvolatile memory
View Patent ↗Disclosed is a nonvolatile memory with a shortened total write time, capable of stably writing data by making a write current constant while reducing fluctuations in a voltage generated by a booster circuit. In a nonvolatile memory such as a flash memory, data is determined at the time of writing operation. While skipping a bit corresponding to write data having the logic “1” (or logic “0”), writing operation to bits corresponding to write data having the logic “0” (or logic “1) is successively performed.
1. A semiconductor device comprising a nonvolatile memory array and a central processing unit,
wherein said nonvolatile memory array comprises a control circuit, a plurality of nonvolatile memory cells including a first nonvolatile memory cell and a second nonvolatile memory cell, a plurality of data lines including a first data line and a second data line, and a word line,
wherein said word line is coupled to both of said first nonvolatile memory cell and said second nonvolatile memory cell,
wherein said first data line is coupled to said first nonvolatile memory cell, and said second data line is coupled to said second nonvolatile memory cell,
wherein said central processing unit is adapted to control a write operation by setting a control bit in a control register,
wherein in said write operation, said control circuit performs control in accordance with said control bit in said control register, said word line is supplied with a program voltage, said first data line is supplied with a first voltage after said program voltage has been supplied to said word line, and said second data line is supplied with said first voltage after a start of suppling said first voltage to said first data line, and
wherein said central processing unit is adapted to control a verify operation, for checking whether data has been written to said first nonvolatile memory cell and said second nonvolatile memory cell, after said first voltage has been supplied to said second data line.
2. A semiconductor device according to claim 1 ,
wherein said first data line and said second data line are supplied with said first voltage during a second period.
3. A semiconductor device according to claim 2 ,
wherein each of said plurality of nonvolatile memory cells has a threshold voltage within an arbitrary one of a plurality of voltage ranges in accordance with data stored therein,
wherein before said write operator, said first nonvolatile memory cell and said second nonvolatile memory cell have a first level theshold voltage within a first voltage range in accordance with a first state of data, and
wherein after said write operation, said first nonvolatile memory cell and said second nonvolatile memory cell have a second level theshold voltage within a second voltage range in accordance with a second state of data.
4. A semiconductor device according to claim 3 ,
wherein in said verify operation, said central processing unit checks whether said threshold voltages of said first nonvolatile memory cell and said second nonvolatile memory cell have reached said second voltage range.
5. A semiconductor device according to claim 4 ,
wherein when said central processing unit detects, in said verify operation, that data has not been written to one or both of said first nonvolatile memory cell and said second nonvolatile memory cell, said central processing unit performs control to repeat said write operation.
6. A semiconductor device according to claim 5 ,
wherein each of said plurality of nonvolatile memory cells has a gate terminal, a source terminal, a drain terminal, and an electron charge area, and
wherein said electron charge area is structured by a floating gate.