US4569120A — Method of fabricating a programmable read-only me…

Claim 1

Independent Claim 159 words

A method of fabricating a semiconductive programmable read only memory cell, comprising: (a) locally oxiding selected surface regions of a body of monocrystalline semiconductor of first type conductivity to produce a plurality of isolated semiconductor regions in said body; (b) introducing dopant impurities of opposite second type conductivity in a first one of said isolated semiconductor regions to produce a first region of second type conductivity forming a semiconductive junction with said body at a location beneath the surface of said body; (c) implanting ions of sufficiently high energy and density within a surface layer of said first region to convert said surface layer to amorphous form that is electrically and irreversibly switchable from high resistance state to low resistance state; and (d) introducing dopant impurities of first type conductivity in a second one of said isolated semiconductor regions lying adjacent to said first isolated region to form a low resistance contact region at the surface of said body.

Claim 2

Independent Claim 159 words

A method of fabricating a semiconductive programmable read only memory cell, comprising: (a) locally oxiding selected surface regions of a body of monocrystalline semiconductor of first type conductivity to produce a plurality of isolated semiconductor regions in said body; (b) introducing dopant impurities of opposite second type conductivity in a first one of said isolated semiconductor regions to produce a first region of second type conductivity forming a semiconductive junction with said body at a location beneath the surface of said body; (c) implanting ions of sufficiently high energy and density within a surface layer of said first region to convert said surface layer to amorphous form that is electrically and irreversibly switchable from high resistance state to low resistance state; and (d) introducing dopant impurities of first type conductivity in a second one of said isolated semiconductor regions lying adjacent to said first isolated region to form a low resistance contact region at the surface of said body.

Claim 3

Dependent Claim 36 words

A method according to claim 1 and further including forming a low resistance semiconductor region of first type conductivity within said body spaced from and lying beneath said semiconductive junction and said low resistance contact region.

Claim 4

Dependent Claim 21 words

A method according to claim 1 wherein said impurity ions in step (c) are ions of neutral conductivity in the semiconductor.

Claim 5

Dependent Claim 18 words

A method according to claim 1 wherein said impurity ions in step (c) are of second type conductivity.

Claim 6

Dependent Claim 16 words

A method according to claim 1 wherein said semiconductor body is lightly doped N type silicon.

Claim 7

Dependent Claim 28 words

A method according to claim 1 wherein the impurity ions in step (c) are implanted with an energy substantially in the range of 10 Kev to 180 Kev.

Claim 8

Dependent Claim 25 words

A method according to claim 1 wherein the impurity ions in step (c) have a dose of 1×10 15 ions per square centimeter or greater.

Claim 9

Dependent Claim 15 words

A method according to claim 7 wherein the impurity ions in step (c) are argon.

Claim 10

Independent Claim 145 words

A method of fabricating a programmable read-only memory cell according to the steps of: creating means to laterally electrically isolate islands of an upper zone of first type conductivity in a monocrystalline semiconductor body; introducing an impurity of opposite second type conductivity into a first of the islands to produce therein a region of second type conductivity extending along the upper surface of the island and forming a PN junction with semiconductive material of the island outside the region; implanting ions of sufficiently high energy and dosage into a layer of the region along its upper surface to convert this surface layer into a highly resistive amorphous form that is electrically and irreversably switchable to a low resistance state; and creating a path of first type conductivity in the body extending from the PN junction through a second of the islands to its upper surface.

Claim 11

Independent Claim 145 words

A method of fabricating a programmable read-only memory cell according to the steps of: creating means to laterally electrically isolate islands of an upper zone of first type conductivity in a monocrystalline semiconductor body; introducing an impurity of opposite second type conductivity into a first of the islands to produce therein a region of second type conductivity extending along the upper surface of the island and forming a PN junction with semiconductive material of the island outside the region; implanting ions of sufficiently high energy and dosage into a layer of the region along its upper surface to convert this surface layer into a highly resistive amorphous form that is electrically and irreversably switchable to a low resistance state; and creating a path of first type conductivity in the body extending from the PN junction through a second of the islands to its upper surface.

Claim 12

Dependent Claim 25 words

A method according to claim 9 wherein the ions implanted into the surface layer are neutral with respect to the first and second type conductivities.

Claim 13

Dependent Claim 17 words

A method according to claim 10 wherein the implanted ions are from Group O (inert gas group).

Claim 14

Dependent Claim 19 words

A method according to claim 9 wherein the ions implanted into the surface layer are of second type conductivity.

Claim 15

Dependent Claim 25 words

A method according to claim 9 wherein the dosage of the ions implanted into the surface layer is at least 10 15 ions/cm 2 .

Claim 16

Dependent Claim 27 words

A method according to claim 9 wherein the ions implanted into the surface layer comprise argon at a dosage of at least 10 15 ions/cm 2 .

Claim 17

Dependent Claim 19 words

A method according to claim 9 wherein the side boundaries of the first island laterally bound the PN junction.

Claim 18

Dependent Claim 65 words

A method according to claim 15 further including the step of forming first and second electrically conductive layers in ohmic contact with the surface layer and the second island, respectively, at their upper surfaces, the surface layer being switched to its low resistance state upon application of a voltage of sufficient magnitude between the conductive layers in the forward conductive direction of the PN junction.

Claim 19

Dependent Claim 11 words

A method according to claim 16 wherein the body comprises silicon.

Claim 20

Dependent Claim 25 words

A method according to claim 17 wherein the conductive layers comprise metal silicide at least where they contact the surface layer and the second island.

Claim 21

Dependent Claim 37 words

A method according to claim 17 wherein: the first conductive layer comprises a non-silicide barrier metal at least along the surface layer; and the second conductive layer comprises a metal silicide at least along the second island.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1989-02-10	1989-08-12	1990-02-11	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1993-02-10	1993-08-12	1994-02-11	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1997-02-10	1997-08-12	1998-02-11	$7700.00	Window Closed / Lapsed

Method of fabricating a programmable read-only memory cell incorporating an antifuse utilizing ion implantation

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag