Segmented column memory array
First Claim
1. In an EPROM or EEPROM of Flash EEPROM integrated circuit memory device, including a two-dimensional array of memory cells organized in rows and columns, each memory cell having a gate, a source and a drain, said two-dimensional array having a word line connected to all the gates in each row, said integrated circuit memory device comprising:
- a plurality of segmented arrays formed by partitioning the two-dimensional array along the column direction, each segmented array being formed by a bank of segmented columns and each segmented column having a pair of independent segmented bit lines connected respectively to all the sources and drains therein, such that each segmented array is addressable column-by-column by an array of segmented bit lines;
cell accessing means connectable to an addressed cell in a segmented array by the word line and the pair of segmented bit lines connected thereto, said cell accessing means further comprising;
a plurality of electrically isolated conductive rails parallel to and overlaying the columns of the two-dimensional array, such that for each segmented column therein, the pair of segmented bit lines thereof is associated with a corresponding pair of conductive rails for access therethrough;
first and second switching transistors for exclusively and switchably connecting the pair of segmented bit lines to the pair of corresponding conductive rails;
each first switching transistor located at a top end of each segmented column for switchably connecting first of the pair of segmented bit lines to first of the pair of corresponding conductive rails; and
said second switching transistor located at a bottom end of each segmented column for switchably connecting second of the pair of segmented bit lines to second of the pair of corresponding conductive rails;
thereby forming in each segmented array, a row of first switching transistors at a top end thereof one-to-one connected to one set of alternate segmented bit lines therein and a row of second switching transistors at a bottom end thereof one-to-one connected to a complement set of alternate segmented bit lines therein, each said row of first or second switching transistors having a pitch double that of the array of segmented bit lines.
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Accused Products
Abstract
In an array of solid-state memory cells organized into rows and segmented columns and addressable by wordlines and bit lines, a memory cell within a segmented column is addressable by segment-select transistors which selectively connect the memory cell'"'"'s pair of bit lines via conductive lines running parallel to the columns to a column decode circuit. The disposition of the segment-select transistors and the conductive lines relative to the segmented columns enables one segment-select transistor to fit in every two or more columns. In one embodiment, the segment-select transistors have double the pitch of the columns while the conductive lines have the same pitch of the columns. In another embodiment, the segment-select transistor have four times the pitch of the columns while the conductive lines have double the pitch of the columns. This enables the use of larger size segment-select transistors which are necessary for passing higher currents in devices such as EPROM or flash EEPROM. Column segmentation effectively isolates defects to individual segments and reduces the capacitance in the source and drain of an address memory cell.
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Citations
11 Claims
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1. In an EPROM or EEPROM of Flash EEPROM integrated circuit memory device, including a two-dimensional array of memory cells organized in rows and columns, each memory cell having a gate, a source and a drain, said two-dimensional array having a word line connected to all the gates in each row, said integrated circuit memory device comprising:
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a plurality of segmented arrays formed by partitioning the two-dimensional array along the column direction, each segmented array being formed by a bank of segmented columns and each segmented column having a pair of independent segmented bit lines connected respectively to all the sources and drains therein, such that each segmented array is addressable column-by-column by an array of segmented bit lines; cell accessing means connectable to an addressed cell in a segmented array by the word line and the pair of segmented bit lines connected thereto, said cell accessing means further comprising; a plurality of electrically isolated conductive rails parallel to and overlaying the columns of the two-dimensional array, such that for each segmented column therein, the pair of segmented bit lines thereof is associated with a corresponding pair of conductive rails for access therethrough; first and second switching transistors for exclusively and switchably connecting the pair of segmented bit lines to the pair of corresponding conductive rails; each first switching transistor located at a top end of each segmented column for switchably connecting first of the pair of segmented bit lines to first of the pair of corresponding conductive rails; and said second switching transistor located at a bottom end of each segmented column for switchably connecting second of the pair of segmented bit lines to second of the pair of corresponding conductive rails; thereby forming in each segmented array, a row of first switching transistors at a top end thereof one-to-one connected to one set of alternate segmented bit lines therein and a row of second switching transistors at a bottom end thereof one-to-one connected to a complement set of alternate segmented bit lines therein, each said row of first or second switching transistors having a pitch double that of the array of segmented bit lines. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In an EPROM or EEPROM of Flash EEPROM integrated circuit memory device, including a two-dimensional array of memory cells organized in rows and columns, each memory cell having a gate, a source and a drain, said two-dimensional array having a word line connected to all the gates in each row, a method of isolating defects that may arise in said array comprising:
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partitioning the two-dimensional array along the column direction to form a plurality of segmented arrays, each segmented array being formed by a bank of segmented columns and each segmented column having a pair of independent segmented bit lines connected respectively to all the sources and drains therein, such that each segmented array is addressable column-by-column by an array of segmented bit lines; selectively connecting a cell accessing means to an addressed cell in a segmented array by the word line and the pair of segmented bit lines connected thereto, said cell accessing means further comprising; a plurality of electrically isolated conductive rails parallel to and overlaying the columns of the two-dimensional array, such that for each segmented column therein, the pair of segmented bit lines thereof is associated with a corresponding pair of conductive rails for access therethrough; first and second switching transistors for exclusively and switchably connecting the pair of segmented bit lines to the pair of corresponding conductive rails; each first switching transistor located at a top end of each segmented column for switchably connecting first of the pair of segmented bit lines to first of the pair of corresponding conductive rails; and each second switching transistor located at a bottom end of each segmented column for switchably connecting second of the pair of segmented bit lines to second of the pair of corresponding conductive rails; thereby forming in each segmented array, a row of first switching transistors at a top end thereof one-to-one connected to one set of alternate segmented bit lines therein and a row of second switching transistors at a bottom end thereof one-to-one connected to a complement set of alternate segmented bit lines therein, each said row of first or second switching transistors having a pitch double that of the array of segmented bit lines; and said two-dimensional array being segmented that a segmented column therein containing a defect is isolated therein.
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11. In an EPROM or EEPROM of Flash EEPROM integrated circuit memory device, including a two-dimensional array of memory cells organized in rows and columns, each memory cell having a gate, a source and a drain, said two-dimensional array having a word line connected to all the gates in each row, a method of reducing capacitance in the source and drain of an adressed memory cell comprising:
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partitioning the two-dimensional array along the column direction to form a plurality of segmented arrays, each segmented array being formed by a bank of segmented columns and each segmented column having a pair of independent segmented bit lines connected respectively to al the sources and drains therein, such that each segmented array is addressable column-by-column by an array of segmented bit lines; selectively connecting a cell accessing means to an addressed cell in a segmented array by the word line and the pair of segmented bit lines connected thereto, said cell accessing means further comprising; a plurality of electrically isolated conductive rails parallel to and overlaying the columns of the two-dimensional array, such that for each segmented column therein, the pair of segmented bit lines thereof is associated with a corresponding pair of conductive rails for access therethrough; first and second switching transistors for exclusively and switchably connecting the pair of segmented bit lines to the pair of corresponding conductive rails; each first switching transistor located at a top end of each segmented column for switchably connecting first of the pair of segmented bit lines to first of the pair of corresponding conductive rails; and each second switching transistor located at a bottom end of each segmented column for switchably connecting second of the pair of segmented bit lines to second of the pair of corresponding conductive rails; thereby forming in each segmented array, a row of first switching transistors at a top end thereof one-to-one connected to one set of alternate segmented bit lines therein and a row of second switching transistors at a bottom end thereof one-to-one connected to a complement set of alternate segmented bit lines therein, each said row of first or second switching transistors having a pitch double that of the array of segmented bit lines; and said two-dimensional array having segmented arrays with independent segmented bit lines that additional capacitance imparted from other segmented bit lines is avoided.
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Specification