EP0379693A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
A non-volatile semiconductor memory device having a circuit for applying a program voltage
Assignee: Toshiba Corp
•
Filing: 1989-12-13
•
Granted: —
•
Expires: 2009-12-13
Abstract
Abstract In a method of applying a voltage pulse for injecting/extracting electrons into/from a non-volatile semiconductor memory in which high and low levels of a threshold voltage corresponding to presence and absence of storage of electrons are caused to correspond to binary information, the method includes the steps of generating a plurality of voltage pulses each having an ability of injecting or extracting only a portion of all electrons to be stored, and applying the plurality of voltage pulses to the non-volatile semiconductor memory to thereby carry out injection/extraction of all the electrons. Since the pulse of a Fowler-Nordheim current flowing through the tunnel insulating film by one voltage pulse is short, the density of holes produced in the tunnel insulating film by such a current pulse is extremely low. As a result, the number of holes trapped by a plurality of Fowler-Nordheim current pulses caused to flow by a plurality of voltage pulses is reduced, so the life time of the tunnel insulating film is prolonged.
Inventors
- 👤 Seiji Yamada
- 👤 Kiyomi Naruke
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 14:46
CPC Classifications
G; G11; G11C; G11C7/00; G11C16/00; G11C16/02; G11C16/06; G11C16/10; G11C16/14
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
94 words
In a method of applying a voltage pulse for carrying out injection/extraction of electrons into/from the non-volatile semiconductor memory in which high and low levels of a threshold voltage corresponding to presence and absence of storage of electrons are caused to correspond to binary information, the improvement comprising the steps of generating a plurality of voltage pulses each having an ability of injecting or extracting only a portion of all electrons to be stored, and applying the plurality of voltage pulses to the non-volatile semiconductor memory to thereby inject or extract all the electrons.
Claim 2
Dependent Claim
94 words
In a method of applying a voltage pulse for carrying out injection/extraction of electrons into/from the non-volatile semiconductor memory in which high and low levels of a threshold voltage corresponding to presence and absence of storage of electrons are caused to correspond to binary information, the improvement comprising the steps of generating a plurality of voltage pulses each having an ability of injecting or extracting only a portion of all electrons to be stored, and applying the plurality of voltage pulses to the non-volatile semiconductor memory to thereby inject or extract all the electrons.
Claim 3
Dependent Claim
28 words
A method as set forth in claim 1, wherein the plurality of voltage pulses are such that their respective peak values gradually rise in order of occurrence thereof.
Claim 4
Dependent Claim
70 words
A method as set forth in claim 1, wherein each of the plurality of voltage pulses is caused to rise steeply so that a Fowler-Nordheim current flows to a non-negligible degree even after each pulse has risen, and wherein each voltage pulse is caused to have a sufficiently short pulse width so as to interrupt, in the course of its fall, the Fowler-Nordheim current flowing after completion of the rise.
Claim 5
Dependent Claim
140 words
In an apparatus for applying a program voltage for a non-volatile semiconductor memory, which is constructed to apply a voltage pulse for carrying out injection/extraction of electrons into/from a selected cell of the non-volatile semiconductor memory cell in which high and low levels of a threshold voltage corresponding to presence and absence of storage of electrons are caused to correspond to binary information, the improvement comprising: means (1) for generating a rectangular pulse having a predetermined voltage level and a predetermined width, chopper means (3, 30) responsive to the rectangular pulse generated by the generation mans (1) to chop it into a plurality of narrow pulses, the narrow pulses each having an ability of injecting or extracting only a portion of all electrons to be stored, and means (9) for supplying the plurality of narrow pulses to the selected cell.
Claim 6
Dependent Claim
140 words
In an apparatus for applying a program voltage for a non-volatile semiconductor memory, which is constructed to apply a voltage pulse for carrying out injection/extraction of electrons into/from a selected cell of the non-volatile semiconductor memory cell in which high and low levels of a threshold voltage corresponding to presence and absence of storage of electrons are caused to correspond to binary information, the improvement comprising: means (1) for generating a rectangular pulse having a predetermined voltage level and a predetermined width, chopper means (3, 30) responsive to the rectangular pulse generated by the generation mans (1) to chop it into a plurality of narrow pulses, the narrow pulses each having an ability of injecting or extracting only a portion of all electrons to be stored, and means (9) for supplying the plurality of narrow pulses to the selected cell.
Claim 7
Dependent Claim
59 words
An apparatus as set forth in claim 4, including limiter means (7) provided between the chopper means (3) and the supply means (9), and responsive to the plurality of narrow pulses from the chopper means (3), thus to limit voltage levels of the respective pulses so that the voltage levels gradually rise in order of occurrence of the pulses.
Claim 8
Dependent Claim
72 words
An apparatus as set forth in claim 4, wherein the chopper means (30) allows each narrow pulse to rise steeply so that a Fowler-Nordheim current flows into the selected cell to a non-negligible degree even after each pulse has risen, and allows each narrow pulse to have a sufficiently short pulse width so as to interrupt, in the course of its fall, the Fowler-Nordheim current flowing after the completion of the rise.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.