Abstract: A method for preparing a deep trench first forms a trench in a semiconductor substrate and a stacked structure in the trench, wherein the stacked structure includes at least one nitrogen-containing layer. A phosphorous oxide layer is then formed on the surface of the nitrogen-containing layer. The phosphorous oxide is then transformed into an etchant in a steam atmosphere to remove the nitrogen-containing layer in the trench. The phosphorous oxide layer in the trench is then removed, and the nitrogen-containing layer can be effectively removed. The method further comprises forming a plurality of crystallites on a portion of the nitrogen-containing layer before the phosphorous oxide layer is formed on the surface of the nitrogen-containing layer, which allows the formation of a deep trench with a rough inner sidewall.

Abstract: A method of forming cell bitline contact plugs is disclosed in the present invention. After providing a semiconductor substrate with a first region and a second region, cell bitline contacts are formed at the first region. After forming bitline pattern openings at the second region, poly spacers are formed on sidewalls of the cell bitline contacts and the bitline pattern openings. A substrate contact and a gate contact are then formed within the openings at the second region. After forming a trench around each of the substrate contact and the gate contact by performing an etching process, cell-bitline contact plugs, a substrate contact plug, and a gate contact plug are formed.

Abstract: 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.

Abstract: 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.

Abstract: The present invention discloses a trench capacitor formed in a trench in a semiconductor substrate. The trench capacitor comprises a bottom electrode positioned on a lower outer surface of the trench, a dielectric layer positioned on an inner surface of the bottom electrode, a top electrode positioned on the dielectric layer, a collar oxide layer positioned on an upper inner surface of the trench, a buried conductive strap positioned on the top electrode, and an interface layer made of silicon nitride positioned at the side of the buried conductive strap. The bottom electrode, the dielectric layer and the top electrode form a capacitive structure. The collar oxide layer includes a first block and a second block, and the height of the first block is larger than the height of the second block. The interface layer is positioned on a portion of the inner surface of the trench above the second block.