| 摘要 |
A memory charge storage node ( 120.1, 120.2, 120.3 ) is at least partially located in a trench ( 124 ). The memory comprises a transistor including a source/drain region ( 170 ) present at a first side ( 124.1 ) but not a second side ( 124.2 ) of the trench. Before forming conductive material ( 120.3 ) providing at least a portion of the charge storage node, a blocking feature ( 704 ) is formed adjacent to the second side ( 124.2 ) to block the conductive material ( 120.3 ). The blocking feature can be dielectric left in the final structure, or can be a sacrificial feature which is removed after the conductive material deposition to make room for dielectric. The blocking features for multiple trenches in a memory array can be patterned using a mask ( 710 ) comprising a plurality of straight strips each of which runs through the memory array in the row direction. The charge storage node has a protrusion ( 120.3 ) at the first side of the trench adjacent to the source/drain region and also has a top surface portion (T) laterally adjacent to the protrusion. The trench sidewall has a substantially straight portion (S) on the second side ( 124.2 ) rising above the top surface portion (T). The dielectric ( 144.1, 144.2, 188 ) on the trench sidewall has a portion ( 188 ) which is thicker on the second side than on the first side of the trench.
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