Claims
- 1. A semiconductor memory device comprising:a plurality of word lines; a plurality of bit lines; a plurality of nonvolatile memory cells each formed of a MIS transistor disposed at each intersection of said word lines and said bit lines, and a threshold voltage of said MIS transistor being externally electrically controllable; a write circuit for writing data to a memory cell located at an intersection of selected ones of said word lines and said bit lines; and a sense amplifier for reading data out of said memory cells, wherein an output current of said sense amplifier is changed according to a combination of ON states of two load transistors having different capacities, to realize a normal data read operation, an erase verify operation, and a write verify operation.
- 2. A semiconductor memory device as claimed in claim 1, wherein a reference voltage is increased to provide a word line with a voltage, which is used to carry out said write verify or erase verify operations on any cell transistor connected to said word line.
- 3. A semiconductor memory device as claimed in claim 1, wherein p-channel type and n-channel type transistors fabricated in the same process are connected in series like diodes to provide a word line with a voltage which is used to carry out said write verify or erase verify operations on any cell transistor connected to said word line.
- 4. A semiconductor memory device as claimed in claim 1, wherein said semiconductor memory device is constituted by a flash memory.
Priority Claims (3)
Number |
Date |
Country |
Kind |
4-324284 |
Dec 1992 |
JP |
|
4-349481 |
Dec 1992 |
JP |
|
5-000304 |
Jan 1993 |
JP |
|
Parent Case Info
This application is a divisional application filed under 37 CFR §1.53(b) of parent application Ser. No. 09/832,916, filed Apr. 12, 2001, now U.S. Pat. No. 6,414,874 which in turn is a divisional of application Ser. No. 09/457,736, filed Dec. 10, 1999, now U.S. Pat. No. 6,288,945, which in turn is a divisional of application Ser. No. 09/081,243, filed May 19, 1998, now abandoned which in turn is a divisional of application Ser. No. 08/822,036, filed Mar. 24, 1997, now U.S. Pat. No. 5,815,440, which in turn is a divisional of application Ser. No. 08/432,723, filed Jun. 6, 1995, now U.S. Pat. No. 5,666,314, which in turn is a divisional of application Ser. No. 08/079,738, filed Jun. 22, 1993, now U.S. Pat. No. 5,452,251.
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