Semiconductor device

Abstract

There is provided a non-volatile memory device capable of improving screening test accuracy while applying voltage below the limit voltage of a high-voltage element in the screening test. The non-volatile memory device (51) includes: a high-voltage generation circuit (7) for generating a high voltage; a high-voltage waveform conversion circuit (58) for inputting the high voltage and converting the voltage waveform; and a memory cell unit (2) for performing data rewrite by applying the converted high voltage. The high-voltage waveform conversion circuit (58) has a test signal input unit TEST. When a test signal is inputted to this test signal input unit, a high voltage inputted from the high-voltage generation circuit (7) is applied to the memory cell unit (2) without converting the voltage waveform.

Description

technical field [0001] The present invention relates to a semiconductor device suitable for use in a nonvolatile memory device such as an EEPROM or a flash memory in which data can be rewritten by applying a high voltage to a memory cell. Background technique [0002] In recent years, EEPROM or flash memory has been widely used to store various programs or store various data in consumer equipment, industrial equipment, and the like. A memory cell constituting an EEPROM or a flash memory injects electrons into a floating gate or releases electrons from the floating gate using tunnel current or hot electrons generated by a high voltage (eg, 15V). As a result, data can be rewritten by changing the threshold value of the memory cell. [0003] In general, semiconductor devices manufactured in a semiconductor factory are subjected to a so-called screening test to remove products that may become defective after shipment with defects. This screening test is performed under conditi...

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Problems solved by technology

[0005] However, if Figure 7 As shown in the waveform a, the high voltage output from the high voltage generating circuit 7, at the time t when data rewriting starts 0 rise sharply

This steep rising edge puts excess stress on the memory cell, resulting in a shortened memory cell life

[0006] Also, the high-voltage elements (specifically, N-type or P-type MOS transistors, etc.) used in the peripheral circuits of the memory cell portion such as the high-voltage generating circuit 7 operate near the limit of their withstand voltage, so In the screening test, it is practically difficult to conduct the test by generating or inputting a higher high voltage from the outside

Therefore, in practice, the test of the memory cell portion having a plurality of memory cells is a test that does not increase the applied high voltage but uses a power supply voltage other than a high voltage, temperature, etc. as severe conditions, so the accuracy of the screening test is not enough.

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