Backside gate line slit structure to reduce wafer bow in a three-dimensional memory device comprising bonded devices
A three-dimensional (3D) memory device includes a memory array device, a peripheral device, an etch stop layer, and a backside gate line slit. The memory array device includes a frontside and a backside, a plurality of memory strings, and a plurality of word lines in a staircase structure coupled to the plurality of memory strings. The peripheral device is above the frontside of the memory array device. The etch stop layer is between the memory array device and the peripheral device. The backside gate line slit extends through the backside of the memory array device to the etch stop layer. The backside gate line slit includes a conductive gate line layer and an insulating gate line layer. The 3D memory device can increase manufacturing efficiency, increase yield, reduce thermal stress, reduce fluorine contamination, increase an overlay window, and decrease overlay errors.
1 . A three-dimensional memory device comprising:
a memory array device having a frontside and a backside, the memory array device comprising a plurality of memory strings coupled to a plurality of word lines in a staircase structure;
an etch stop layer disposed on the frontside of the memory array device;
a peripheral device disposed on the etch stop layer, the etch stop layer being between the memory array device and the peripheral device; and
a backside gate line slit extending through the backside of the memory array device to the etch stop layer, the backside gate line slit comprising a conductive gate line layer and an insulating gate line layer, wherein a cross-sectional diameter of the backside gate line slit decreases from the backside of the memory array device towards the frontside of the memory array device, and wherein a cross-sectional diameter of each of the plurality of memory strings increases from the backside of the memory array device towards the frontside of the memory array device.
2 . The three-dimensional memory device of claim 1 , wherein the insulating gate line layer is between the etch stop layer and the conductive gate line layer.
3 . The three-dimensional memory device of claim 1 , further comprising an array common source coupled to the plurality of memory strings and the backside gate line slit.
4 . The three-dimensional memory device of claim 3 , wherein the insulating gate line layer is between the conductive gate line layer and the array common source.
5 . The three-dimensional memory device of claim 1 , wherein the insulating gate line layer comprises a high-k dielectric layer.
6 . The three-dimensional memory device of claim 1 , wherein the plurality of word lines each comprises a word line insulating layer, the word line insulating layer comprising a high-k dielectric layer.
7 . The three-dimensional memory device of claim 1 , wherein the plurality of memory strings each comprises a pillar and an insulating layer surrounding the pillar, the insulating layer comprising a high-k dielectric layer.
8 . The three-dimensional memory device of claim 1 , further comprising a pad-out interconnection layer coupled to the backside of the memory array device.
9 . The three-dimensional memory device of claim 1 , wherein the etch stop layer comprises a thickness in a range of about 5 nm to about 50 nm.
10 . A method for forming a three-dimensional memory device, the method comprising the steps of:
(a) forming a plurality of memory strings through a dielectric stack;
(b) forming a staircase structure in the dielectric stack to form a memory array device having a frontside and a backside, wherein a cross-sectional diameter of each of the plurality of memory strings increases from the backside of the memory array device towards the frontside of the memory array device;
(c) forming an etch stop layer on the frontside of the memory array device;
(d) forming a plurality of interconnections through the etch stop layer to the plurality of memory strings and the staircase structure of the memory array device;
(e) bonding a peripheral device above the memory array device to the plurality of interconnections; and
(f) forming a backside gate line slit extending through the backside of the memory array device to the etch stop layer, the backside gate line slit comprising a conductive gate line layer and an insulating gate line layer, wherein a cross-sectional diameter of the backside gate line slit decreases from the backside of the memory array device towards the frontside of the memory array device.
11 . The method of claim 10 , wherein forming the backside gate line slit comprises forming the insulating gate line layer between the etch stop layer and the conductive gate line layer.
12 . The method of claim 10 , further comprising forming an array common source coupled to the plurality of memory strings and the backside gate line slit.
13 . The method of claim 12 , wherein forming the backside gate line slit comprises forming the insulating gate line layer between the conductive gate line layer and the array common source.
14 . The method of claim 10 , wherein forming the backside gate line slit comprises forming the insulating gate line layer with a high-k dielectric layer.
15 . The method of claim 10 , wherein forming the backside gate line slit comprises forming a plurality of word lines in the staircase structure, the plurality of word lines coupled to the plurality of interconnections.
16 . The method of claim 15 , wherein forming the plurality of word lines comprises forming a word line insulating layer comprising a high-k dielectric layer.
17 . The method of claim 10 , wherein forming the plurality of memory strings comprises forming a pillar and an insulating layer surrounding the pillar.
18 . The method of claim 17 , wherein the insulating layer comprises a high-k dielectric layer.
19 . The method of claim 10 , further comprising forming a pad-out interconnection layer coupled to the backside of the memory array device.
20 . The method of claim 10 , wherein forming the etch stop layer with a thickness in a range of about 5 nm to about 50 nm.