Semiconductor memory device and method for manufacturing same
According to one embodiment, a semiconductor memory device includes a stacked body and a column. The stacked body includes a plurality of electrode layers. The column includes a semiconductor channel, a charge storage film, and a doped silicon layer. The semiconductor channel extends in the stacking direction. The semiconductor channel is a polycrystalline. An average grain size of crystals in a polycrystalline is not less than a film thickness of the semiconductor channel. The charge storage film is provided between the semiconductor channel and the electrode layers. The doped silicon layer contains a metal element and an impurity other than a metal element. The doped silicon layer is in contact with a top end of the semiconductor channel.
1. A semiconductor memory device comprising:
a stacked body including a plurality of electrode layers, an insulator being interposed between the electrode layers; and
a column extending in a stacking direction in the stacked body;
the column including
a semiconductor channel extending in the stacking direction, the semiconductor channel being a polycrystalline, an average grain size of crystals in the polycrystalline being not less than a film thickness of the semiconductor channel, the film thickness being a thickness along a direction perpendicular to an extending direction of the semiconductor channel,
a charge storage film provided between the semiconductor channel and one of the electrode layers, and
a doped silicon layer containing a metal element and a non-metallic impurity, the doped silicon layer being in direct contact with a top end of the semiconductor channel.
2. The device according to claim 1 , wherein the doped silicon layer contains at least one of phosphorus, arsenic, boron, and carbon as the impurity.
3. The device according to claim 2 , wherein an impurity concentration of the doped silicon layer is higher than an impurity concentration of the semiconductor channel.
4. The device according to claim 1 , wherein the doped silicon layer contains at least one of nickel, cobalt, and palladium as the metal element.
5. The device according to claim 4 , wherein a concentration of the metal element in the doped silicon layer is higher than an impurity concentration of the semiconductor channel.
6. The device according to claim 4 , wherein a concentration of the metal element in the semiconductor channel is not higher than 1×10 19 [atoms/cc].
7. The device according to claim 1 , wherein the semiconductor channel contains a polycrystalline silicon, an average grain size of crystals in the polycrystalline silicone being not less than a film thickness of the semiconductor channel, the film thickness being a thickness along a direction perpendicular to an extending direction of the semiconductor channel.
8. The device according to claim 1 , further comprising a selection gate layer provided above the stacked body.
9. The device according to claim 8 , wherein a bottom end of the doped silicon layer is positioned higher than a top face of the selection gate layer.
10. The device according to claim 1 , wherein
the semiconductor channel is provided in a tubular shape, and
the doped silicon layer is provided on an inner side of a top portion of the semiconductor channel, and directly contacts a side surface of the top portion of the semiconductor channel.
11. The device according to claim 10 , wherein an impurity concentration of the top portion of the semiconductor channel is higher than an impurity concentration of a portion that faces one of the electrode layers in the semiconductor channel.
12. The device according to claim 10 , further comprising
a selection gate layer provided above the stacked body, and
an insulating film provided on an inner side of the semiconductor channel,
wherein
a boundary of a bottom end of the doped silicon layer and the insulating film is positioned higher than a top face of the selection gate layer.
13. The device according to claim 1 , wherein
the doped silicon layer contains at least one of nickel, cobalt, and palladium as the metal element,
the doped silicon layer contains at least one of phosphorus, arsenic, boron, and carbon as the impurity, and
an impurity concentration of the doped silicon layer is higher than a metal element concentration of the doped silicon layer.