Semiconductor memory device with oxide semiconductor transistor
First Claim
1. A semiconductor device comprising:
- n bit lines, n being a natural number;
m memory cells electrically connected to one of the bit lines, m being a natural number; and
m+1 word lines,wherein each of the memory cells comprises;
a first transistor comprising a first gate electrode, a first source electrode, and a first drain electrode;
a second transistor comprising a second gate electrode, a second source electrode, and a second drain electrode; and
a capacitor,wherein the second transistor includes an oxide semiconductor layer,wherein the one of the bit lines is electrically connected to the first drain electrode and the second drain electrode of a (k−
1)-th memory cell,wherein a k-th word line is electrically connected to the second gate electrode of a k-th memory cell and is electrically connected to the first source electrode and one electrode of the capacitor of the (k−
1)-th memory cell, k being a natural number of greater than or equal to 2 and less than or equal to m+1, andwherein the first gate electrode of the (k−
1)-th memory cell, the second source electrode of the (k−
1)-th memory cell, and the other electrode of the capacitor of the (k−
1)-th memory cell are electrically connected to one other.
1 Assignment
0 Petitions
Accused Products
Abstract
An object is to provide a semiconductor device which can hold stored data even when not powered and which achieves high integration by reduction of the number of wirings. The semiconductor device is formed using a material which can sufficiently reduce the off-state current of a transistor, e.g., an oxide semiconductor material which is a wide bandgap semiconductor. When a semiconductor material which allows a sufficient reduction in the off-state current of a transistor is used, data can be held for a long period. One line serves as the word line for writing and the word line for reading and one line serves as the bit line for writing and the bit line for reading, whereby the number of wirings is reduced. Further, by reducing the number of source lines, the storage capacity per unit area is increased.
114 Citations
17 Claims
-
1. A semiconductor device comprising:
-
n bit lines, n being a natural number; m memory cells electrically connected to one of the bit lines, m being a natural number; and m+1 word lines, wherein each of the memory cells comprises; a first transistor comprising a first gate electrode, a first source electrode, and a first drain electrode; a second transistor comprising a second gate electrode, a second source electrode, and a second drain electrode; and a capacitor, wherein the second transistor includes an oxide semiconductor layer, wherein the one of the bit lines is electrically connected to the first drain electrode and the second drain electrode of a (k−
1)-th memory cell,wherein a k-th word line is electrically connected to the second gate electrode of a k-th memory cell and is electrically connected to the first source electrode and one electrode of the capacitor of the (k−
1)-th memory cell, k being a natural number of greater than or equal to 2 and less than or equal to m+1, andwherein the first gate electrode of the (k−
1)-th memory cell, the second source electrode of the (k−
1)-th memory cell, and the other electrode of the capacitor of the (k−
1)-th memory cell are electrically connected to one other. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. A semiconductor device comprising:
-
a first wiring; a second wiring; a third wiring; a first memory cell comprising; a first transistor comprising; a first gate; a first source; and a first drain; a second transistor comprising; a second gate; a second source; and a second drain; and a first capacitor; and a second memory cell comprising; a third transistor comprising; a third gate; a third source; and a third drain; and a fourth transistor comprising; a fourth gate; a fourth source; and a fourth drain; wherein each of the second transistor and the fourth transistor includes an oxide semiconductor layer, wherein the first wiring is electrically connected to one of the first source and the first drain, one of the second source and the second drain, one of the third source and the third drain, and one of the fourth source and the fourth drain, wherein the second wiring is connected to the second gate, wherein the third wiring is electrically connected to one of electrodes of the first capacitor, and the other of the first source and the first drain, wherein the third wiring is electrically connected to the fourth gate, wherein the first gate is electrically connected to the other of the second source and the second drain, and the other of electrodes of the first capacitor, and wherein the third gate is electrically connected to the other of the fourth source and the fourth drain. - View Dependent Claims (13, 14, 15, 16, 17)
-
Specification