Disclosed herein is a solid state, directly overwritable, non-volatile, high density, low cost, low energy, high speed, readily manufacturable, single cell memory element having reduced switching current requirements and an increased thermal stability of data retention. The memory element includes a volume of memory material which is a transition metal modified chalcogen. The transition metal may be selected from the group consisting of Nb, Pd, Pt and mixtures or alloys thereof. The memory material may further include at least one transition metal selected from the group consisting of Fe, Cr, Ni and mixtures or alloys thereof. The memory element exhibits orders of magnitude higher switching speeds at remarkably reduced switching energy levels. The novel memory element of the instant invention is in turn characterized, inter alia, by at least two stable and non-volatile detectable configurations of local atomic and/or electronic order, which configurations can be selectively and repeatably accessed by electrical input signals of designated energy levels. The memory elements are further characterized by enhanced thermal stability of data retention, which stability is achieved by elementally modifying Te--Ge--Sb semiconductor material from which previous memory elements were fabricated.
RELATED APPLICATION INFORMATION
This application is a continuation-in-part of U.S. application Ser. No. 08/423,484 filed Mar. 19, 1995, which is a continuation-in-part of U.S. application Ser. No. 07/789,234 filed Nov. 7, 1991, now U.S. Pat. No. 5,414,271 which is a continuation-in-part of U.S. application Ser. No. 07/768,139, filed Sep. 30, 1991, now U.S. Pat. No. 5,335,219, and a continuation-in-part of U.S. application Ser. No. 07/747,053 filed Aug. 19, 1991, now U.S. Pat. No. 5,296,716, each of which in turn is a continuation-in-part of U.S. application Ser. No. 07/642,984 filed Jan. 18, 1991, now U.S. Pat. No. 5,166,758.
A phase change material memory cell may be formed with singulated, cup-shaped phase change material. The interior of the cup-shaped phase change material may be filled with a thermal insulating material. As a result, heat losses upwardly through the phase change material may be reduced and adhesion problems between the phase change material and the rest of the device may likewise be reduced in some embodiments. In addition, a barrier layer may be provided between the upper electrode and the remainder of the device that may reduce species incorporation from the top electrode into the phase change material, in some embodiments. Chemical mechanical planarization may be utilized to define the phase change material reducing the effects of phase change material dry etching in some embodiments.
A memory may be implemented with a stable chalcogenide glass which is defined as a generally amorphous chalcogenide material that does not change to a generally crystalline phase when exposed to 200.degree. C. for 30 minutes or less. Different states may be programmed by changing the threshold voltage of the material. The threshold voltage may be changed with pulses of different amplitude and/or different pulse fall times. Reading may be done using a reference level between the threshold voltages of the two different states. A separate access device is generally not needed.
Provided are a phase-change memory device using a phase-change material having a low melting point and a high crystallization speed, and a method of fabricating the same. The phase-change memory device includes an antimony (Sb)-selenium (Se) chalcogenide Sb.sub.xSe.sub.100-x phase-change material layer contacting a heat-generating electrode layer exposed through a pore and filling the pore. Due to the use of Sb.sub.xSe.sub.100-x in the phase-change material layer, a higher-speed, lower-power consumption phase-change memory device than a GST memory device can be manufactured.
A memory system comprising memory cells and reference cells each including a programmable resistance element. The resistance state of a memory cell is determined by comparing a sense signal developed by the memory cell with a reference signal developed by one or more of the reference cells. The programmable resistance elements may comprise a phase-change material.
The electric device (100) has a body (102) having a resistor (107) comprising a phase change material being changeable between a first phase and a second phase. The resistor (107) has a first electrical resistance when the phase change material is in the first phase, and a second electrical resistance, different from the first electrical resistance, when the phase change material is in the second phase. The phase change material constitutes a conductive path between a first contact area and a second contact area. A cross-section of the conductive path is smaller than the first contact area and the second contact area. The body (102) may further have a heating element 106 being able to conduct a current for enabling a transition from the first phase to the second phase. The heating element (106) is preferably arranged in parallel with the resistor (107).
