JPH06259978A - Flash erasing type non-volatile memory - Google Patents

Abstract

PURPOSE:To shorten the time required for erasure and erasure verification by storing the number of times required for reading out and checking whether the erasure of a cell region ends normally or not after the erasure operation. CONSTITUTION:A memory cell is erased after the start of erasure and the verification 44 to read out and check whether the erasure ends normally or not is executed. This execution is executed until the erasure ends A5. The erasure is ended by storing the number of the verification times into a a verification count memory section A3. Only the erasure is executed up to the number of the times stored in the verification count memory section before the start of the erasure A1 and the erasure A2. The erasure is executed again when the erasure does not end even at the number of times stored in the memory section. As a result, the time for the erasure and the erasure verification is shortened and the erasure time is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash erase type nonvolatile memory.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional flash erasing type non-volatile memory starts erasing (step A).
1) After the memory cell is erased (step A2), verify (read) is performed (step A3) in order to confirm whether the erase is normally completed. If erasing has not been completed (NO), erasing and verifying are performed again, and erasing and verifying are repeated until erasing is completed (OK), and erasing is completed (step A4). .

Here, there is a step between step A1 and step A2 in which a counter is set to n = 0 and [n + 1] is set to [n].

[0004]

In the conventional flash erasing type non-volatile memory, since erasing and erasing verification are repeated until erasing is completed, the erasing and erasing verification time becomes long, and erasing and erasing verification are required. This caused an increase in erase time.

An object of the present invention is to solve the above-mentioned problems and to provide a flash erase type non-volatile memory in which the time required for erase and erase verify is shortened.

[0006]

The structure of the flash erase type non-volatile memory of the present invention stores the number of erase verify times required after the erase is completed until the erase of the erased cell area is normally completed. A verify count storage unit is provided.

[0007]

The present invention will be described below with reference to the drawings. FIG. 1 is a flow chart showing the first erase and verify operations in a memory according to an embodiment of the present invention. FIG. 2 is a flow chart showing the second and subsequent erases and verifications in the memory according to the embodiment of the present invention.

First, the operation of this embodiment will be described with reference to FIG. 1 and then with reference to FIG. In FIG. 1, after erasing is started (step A1), the memory cell is erased (step A2), and verification is performed to confirm whether the memory cell has been erased normally (step A3) until the erase is completed. , Erase from (step A2), and if the verify in (step A3) is completed in the fifth time,
The verify count storage unit (step A4) stores 5 times (n = z), and the erasing ends (step A5).

In FIG. 2, erase start (step A
1) and deletion (step A2) are the same as in FIG. 1, but 1
Since the verify count storage section (step A3) stores 5 times in the erase verification of the fifth time, only the erase is performed up to the fifth time, and if the fifth time is exceeded thereafter, the verify is performed (step A4), and the memory is stored again. 5 stored in the department
When the erasing is not completed even after the number of times, the erasing is performed again (step A2), and the erasing is completed by repeating the erasing and erasing verification until the erasing is completed (step A2).
5).

[0010]

As described above, the flash erase type non-volatile memory according to the present invention stores the number of erase verify times required until the normal end of the erase, and the stored number of times at the next erase. Since only the erasing is performed up to the above, there is an effect that the erasing and erasing verification time is shortened and the erasing time is shortened.

[Brief description of drawings]

FIG. 1 is a flow chart of a first erase and verify in an embodiment of the present invention.

FIG. 2 is a flow chart of erasing and verifying after the second time in the embodiment of the present invention.

FIG. 3 is a flow chart of conventional erasing and verifying.

[Explanation of symbols]

 A1, A2, A3, A4, A5 steps

Claims (2)

[Claims] 1. A flash comprising a verify count storage unit for storing the number of times required to confirm whether or not the erased cell area has been normally erased after the erase operation. Erasable nonvolatile memory. 2. The flash erase type non-volatile memory according to claim 1, further comprising means for performing only erase without performing verify up to the number of times stored in the verify count storage unit.