Phase change memory device and method of manufacturing the device
View Patent ↗The invention provides a novel structure of a phase change memory device. In the phase change memory device of the invention, an electrode acting as a radiating fin does not exit immediately above a phase change area of a phase change layer ( 115 ). A heater electrode ( 111 ) and landing electrode layer ( 113 a, 114 a ) both contact the bottom of the phase change layer ( 115 ) made of GST. The landing electrode layer ( 113 a, 114 a ) contacts the bottom of the phase change layer ( 115 ) to partially overlap in a region off from a portion immediately above the contact face (Y) of the phase change layer and heater electrode. The contact electrode ( 116, 118 ) is directly connected to the landing electrode layer ( 113 a, 114 a ) in a portion off from a portion immediately above the heater electrode ( 111 ). The phase change layer of GST or the like does not exist immediately below the contact electrode.
1. A semiconductor device comprising:
a first insulating layer having an upper surface,
a heater electrode selectively formed in the first insulating layer, the heater electrode having a top surface that is substantially coplanar with the upper surface of the first insulating layer;
a second insulating layer formed to cover the upper surface of the first insulating layer and the top surface of the heater electrode, the second insulating layer including a hole that exposes a part of the top surface of the heater electrode, a remaining part of the top surface of the heater electrode being kept covered by the second insulating layer;
a landing electrode selectively formed on the second insulating layer, the landing electrode thereby including a first surface on a side of the second insulating layer and a second surface opposed to the first surface; and
a phase change layer formed in contact with the part of the heater electrode through the hole, the phase change layer including an elongated portion that is elongated over and in contact with a part of the second surface of the landing electrode with an separation from the remaining part of the top surface of the heater electrode by the second insulating layer.
2. The device as claimed in claim 1 , wherein the hole further exposes a part of the upper surface of the first insulating layer together with the part of the top surface of heater electrode, and the phase change layer is in contact with the respective parts of the upper surface of the first insulating layer and of the top surface of the heater electrode.
3. The device as claimed in claim 1 , wherein the hole has a lower side on a side of the first insulating layer and an upper side on a side of the landing electrode, the lower side being smaller than the upper side, the second insulating layer including a first edge defining the lower side of the hole and a second edge defining the upper side of the hole.
4. The device as claimed in claim 3 , wherein the landing electrode is terminated at a peripheral edge thereof that is substantially aligned with a part of the second edge of the second insulating layer, and the elongated portion of the phase change layer is further in contact with the peripheral edge of the landing electrode.
5. The device as claimed in claim 4 , wherein the second insulating layer includes a slant side surface connecting the first and second edges thereof.
6. The device as claimed in claim 1 , further comprising:
a third insulating layer covering the phase change layer and the landing electrode, the third insulating layer including a contact hole that exposes a portion of the second surface of the landing electrode which is apart from the part of the second surface of the landing electrode; and
a contact electrode formed in the contact hole in contact with the portion of the second surface of the landing electrode.
7. A semiconductor device comprising:
a semiconductor substrate having a main surface;
a heater electrode formed over the main surface of the semiconductor substrate, the heater electrode having a top surface that is substantially in parallel to the main surface of the semiconductor substrate,
a first insulating film formed to cover the heater electrode and the semiconductor substrate, the first insulating film having a first hole that exposes a part of the top surface of the heater electrode, a remaining part of the top surface of the heater electrode being kept covered by the first insulating film,
a landing electrode selectively formed on the first insulating film, the landing electrode having a lower surface in contact with the first insulating film and an upper surface opposed to the lower surface;
a phase change layer including a first portion that is in contact with the part of the top surface of the heater electrode though the first hole and a second portion that is elongated from the first portion over a first part of the upper surface of the landing electrode in contact therewith;
a second insulating film formed to cover the landing electrode and the phase change layer, the second insulating film having a second hole that exposes a second part of the upper surface of the landing electrode, the second insulating film keeping covering a third part of the upper surface of the landing electrode between the first and second parts of the upper surface of the landing electrode; and
a contact electrode formed in contact with the second part of the upper surface of the landing electrode through the second hole.
8. The device as claimed in claim 7 , wherein the first hole is formed in tapered shape.
9. The device as claimed in claim 7 , wherein the first hole is formed in tapered shape with a first angle and the second hole is formed in a tapered shape with a second angle that is different from the first angle.
10. The device as claimed in claim 9 , wherein the first angle is lager than the second angle.
11. The device as claimed in claim 7 , further comprising an upper electrode formed on the second insulating film in contact with the contact electrode.
12. The device as claimed in claim 11 , further comprising a lower electrode formed between the heater electrode and the semiconductor substrate in contact with the heater electrode.