Method of making an electrically programmable, electrically erasable memory array cell
First Claim
1. A method for fabricating at least first and second electrically erasable and programmable memory cells at a face of a semiconductor layer having a first conductivity type, comprising the steps of:
- selectively doping the semiconductor layer with a dopant of a second conductivity type opposite the first conductivity type to create a drain region of the first cell, a shared source region spaced from the drain region of the first cell by a channel region of the first cell, and a drain region of the second cell spaced from the source region by a channel region of the second cell;
differentially growing an insulator layer over the face to create thick insulator regions over the source and drain regions, and a relatively thin insulator layer in between the source region and the drain regions;
selectively removing the thin insulator layer to expose first and second window areas on the source region adjacent the channel regions of the respective first and second cells;
forming a first conductive layer over the face;
selectively etching the first conductive layer to define first and second floating gate conductors, each formed over a respective thin window insulator and the channel adjacent the respective thin window insulator; and
forming a control gate conductor insulatively adjacent the floating gate conductors.
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Accused Products
Abstract
A pair of electrically erasable, electrically programmable memory cells are formed at a face of a semiconductor layer (10) and include respective drain regions (30a, 30b), a shared source region (28) and respective channel regions (38a, 38b). Each cell has a floating gate conductor (46a, 46b) which may be programmed by hot electron injection and erased by Fowler-Nordheim electron tunneling through respective tunneling oxide windows (40a, 40b) overlying a portion of source region (28) adjacent respective channels (38a, 38b). A wordline or control gate conductor (62) is insulatively disposed adjacent the floating gates (46a, 46b) to program or erase.
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Citations
4 Claims
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1. A method for fabricating at least first and second electrically erasable and programmable memory cells at a face of a semiconductor layer having a first conductivity type, comprising the steps of:
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selectively doping the semiconductor layer with a dopant of a second conductivity type opposite the first conductivity type to create a drain region of the first cell, a shared source region spaced from the drain region of the first cell by a channel region of the first cell, and a drain region of the second cell spaced from the source region by a channel region of the second cell; differentially growing an insulator layer over the face to create thick insulator regions over the source and drain regions, and a relatively thin insulator layer in between the source region and the drain regions; selectively removing the thin insulator layer to expose first and second window areas on the source region adjacent the channel regions of the respective first and second cells; forming a first conductive layer over the face; selectively etching the first conductive layer to define first and second floating gate conductors, each formed over a respective thin window insulator and the channel adjacent the respective thin window insulator; and forming a control gate conductor insulatively adjacent the floating gate conductors. - View Dependent Claims (2, 3, 4)
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Specification