Electrical fuse device based on a phase-change memory element and corresponding programming method

Abstract

A fuse device has a fuse element provided with a first terminal and a second terminal and an electrically breakable region, which is arranged between the first terminal and the second terminal and is configured to undergo breaking as a result of the supply of a programming electrical quantity, thus electrically separating the first terminal from the second terminal. The electrically breakable region is of a phase-change material, in particular a calcogenic material, for example GST.

1 . A fuse device, comprising: 
 a fuse element having a first terminal; a second terminal; a phase-change region, including an electrically breakable region of phase-change material configured to undergo breaking as a result of the supply of a programming electrical quantity; and a heating element of conductive material in contact with said first terminal, said electrically breakable region being arranged at a contact area between said heating element and said phase-change region; and    a selector element electrically connected to said fuse element and configured to enable the supply of said programming electrical quantity to said fuse element.    
     
     
         2 . The fuse device according to  claim 1 , wherein said phase-change material is a calcogenic material, in particular GST.  
     
     
         3 . The fuse device according to  claim 1 , wherein said contact area is at a bottom side of the phase-change region and the second terminal contacts a top side of the phase-change region, the fuse device further comprising an electrical connection element connecting the selector element to the phase-change region via the second terminal.  
     
     
         4 . The fuse device according to  claim 1 , wherein said selector element is a transistor element having a current input terminal and a current output terminal.  
     
     
         5 . The fuse device according to  claim 4 , wherein said selector element is configured to enable supply to said electrically breakable region of a programming pulse with a current comprised between 2 mA and 3 mA, a voltage comprised between 2 V and 3 V, and a duration comprised between 100 ns and 1 μs.  
     
     
         6 . The fuse device according to  claim 4 , wherein said heating element has a rectangular ring shape having a first long side and a second long side including conductive material, said first long side being arranged above said selector element and said second long side being spaced apart from said selector element; and wherein said electrically breakable region is in contact with said second long side, and said current input terminal is connected to said first long side.  
     
     
         7 . The fuse device according to  claim 4 , wherein said first terminal is connected to said current output terminal, said second terminal is connected to a first line set at a first potential, and said current input terminal is connected to a second line set at a second potential, higher than said first potential.  
     
     
         8 . The fuse device according to  claim 7 , wherein said selector element is a P-channel planar MOSFET.  
     
     
         9 . The fuse device according to  claim 4 , wherein said current input terminal is connected to said second terminal, said current output terminal is connected to a first line set at a first potential, and said first terminal is connected to a second line set at a second potential, higher than said first potential.  
     
     
         10 . The fuse device according to  claim 9 , wherein said selector element is formed in a substrate of semiconductor material, and said first terminal is in contact with a first connection line provided above said substrate, the fuse device further comprising: first contact elements connecting said current input terminal to a second connection line of conductive material; second contact elements connecting said second connection line to said second terminal; and third contact elements connecting said first connection line to said second line.  
     
     
         11 . The fuse device according to  claim 1 , wherein said fuse element has a vertical structure, and said electrically breakable region has a cross section with sublithographic dimensions.  
     
     
         12 . The fuse device according to  claim 1 , wherein, in at least one operating condition, said first terminal has a voltage higher than a voltage of said second terminal, and said programming electrical quantity comprises a programming current flowing from said first terminal to said second terminal.  
     
     
         13 . The fuse device according to  claim 1 , wherein the contact area is laterally spaced apart from the selector element.  
     
     
         14 . The fuse device according to  claim 1 , wherein the heater element is a vertically-arranged thin film of conductive material that contacts the phase-change region at the contact area, which has a sublithographic dimension.  
     
     
         15 . A one-time-programmable storage device, comprising 
 a plurality of fuse devices, each fuse device including:    a fuse element having a first terminal; a second terminal; a phase-change region, including an electrically breakable region of phase-change material configured to undergo breaking as a result of the supply of a programming electrical quantity; and a heating element of conductive material in contact with said first terminal, said electrically breakable region being arranged at a contact area between said heating element and said phase-change region; and    a selector element electrically connected to said fuse element and configured to enable the supply of said programming electrical quantity to said fuse element.    
     
     
         16 . The storage device according to  claim 15 , further comprising a programming circuit configured to supply to at least one of said fuse devices said programming electrical quantity.  
     
     
         17 . The storage device according to  claim 15 , wherein said contact area is at a bottom side of the phase-change region and the second terminal contacts a top side of the phase-change region, the fuse device further comprising an electrical connection element connecting the selector element to the phase-change region via the second terminal.  
     
     
         18 . The storage device according to  claim 15 , wherein said selector element is configured to enable supply to said electrically breakable region of a programming pulse with a current comprised between 2 mA and 3 mA, a voltage comprised between 2 V and 3 V, and a duration comprised between 100 ns and 1 μs.  
     
     
         19 . The storage device according to  claim 15 , wherein said selector element is a transistor element having a current input terminal and a current output terminal, and wherein said heating element has a rectangular ring shape having a first long side and a second long side including conductive material, said first long side being arranged above said selector element and said second long side being spaced apart from said selector element; and wherein said electrically breakable region is in contact with said second long side, and said current input terminal is connected to said first long side.  
     
     
         20 . The storage device according to  claim 15 , wherein said selector element is a P-channel planar MOSFET.  
     
     
         21 . The storage device according to  claim 15 , wherein said selector element is a transistor element having a current input terminal and a current output terminal, and wherein said selector element is formed in a substrate of semiconductor material, and said first terminal is in contact with a first connection line provided above said substrate, the fuse device further comprising: first contact elements connecting said current input terminal to a second connection line of conductive material; second contact elements connecting said second connection line to said second terminal; and third contact elements connecting said first connection line to said second line.  
     
     
         22 . The storage device according to  claim 15 , wherein said fuse element has a vertical structure, and said electrically breakable region has a cross section with sublithographic dimensions.  
     
     
         23 . The storage device according to  claim 15 , wherein the contact area is laterally spaced apart from the selector element.  
     
     
         24 . A method for programming a fuse device provided with a fuse element having a first terminal; a second terminal; a phase-change region, including an electrically breakable region of phase-change material arranged between said first and second terminals; and a heating element of conductive material in contact with said first terminal, said electrically breakable region being arranged at a contact area between said heating element and said phase-change region, the method comprising breaking said electrically breakable region, wherein breaking said electrically breakable region comprises supplying to said phase-change material a programming electrical quantity such as to cause breaking thereof, wherein supplying the programming electrical quantity comprises supplying a programming current flowing between said first terminal and said second terminal so as to form a void in said electrically breakable region.  
     
     
         25 . The method according to  claim 24 , wherein supplying the programming electrical quantity comprises supplying to said electrically breakable region a programming pulse with a current comprised between 2 A and 3 A, a voltage comprised between 2 V and 3 V, and a duration comprised between 100 ns and 1 μs.  
     
     
         26 . The method according to  claim 24 , wherein supplying a programming electrical quantity comprises supplying a programming current flowing from said first terminal to said second terminal so as to form the void in said electrically breakable region.  
     
     
         27 . The method according to  claim 24 , further comprising programming said electrically breakable region in a first low-resistivity operating condition, so as to electrically connect said first and second terminals, and programming said electrically breakable region in a second high-resistivity operating condition, so as to electrically disconnect said first terminal from said second terminal; programming in said second high-resistivity operating condition comprising said step of breaking said electrically breakable region.  
     
     
         28 . A process for manufacturing a fuse device, comprising: 
 forming a fuse element using steps including: 
 forming a first terminal and a second terminal; and  
 forming an electrically breakable region between said first terminal and said second terminal, wherein forming the electrically breakable region comprises forming a region of phase-change material; and  
 forming a heating element of conductive material in contact with said first terminal, said electrically breakable region being arranged at a contact area between said heating element and said electrically breakable region; and  
   forming a selector element electrically connected to said fuse element and configured to enable the supply of said programming electrical quantity to said fuse element.    
     
     
         29 . The process according to  claim 28 , wherein said contact area is at a bottom side of the phase-change region and the second terminal contacts a top side of the phase-change region, the process further comprising forming an electrical connection element connecting the selector element to the phase-change region via the second terminal.  
     
     
         30 . The process according to  claim 28 , wherein said selector element is a transistor element having a current input terminal and a current output terminal, and wherein said heating element has a rectangular ring shape having a first long side and a second long side including conductive material, the process further comprising arranging said first long side above said selector element and spacing apart said second long side from said selector element; and wherein said electrically breakable region is in contact with said second long side, and said current input terminal is connected to said first long side.  
     
     
         31 . The process according to  claim 28 , wherein the contact area is laterally spaced apart from the selector element.