Detection and reduction of dielectric breakdown in semiconductor devices

Abstract

Methods for detecting the breakdown potential of a semiconductor device having a thin dielectric layer are disclosed. The method includes measuring a spectroscopy of the thin dielectric layer and determining whether the spectroscopy exhibits the presence of a breakdown precursor (H 2 , H interstitial radical, H attached radical, and H attached dimer). Preferably, the method is carried out in the presence of a substantially significant applied electric field across dielectric layer. A semiconductor device tested in accordance with this method is also disclosed. Additionally, methods for reducing dielectric breakdown of a semiconductor device having a thin dielectric layer involving the substitution of a second molecule for H 2 molecules present in the dielectric. This second molecule preferably does not react with Si or O to form an undesired attached state and may be an inert gas having a molecular size approximating that of a Hydrogen atom, such as Helium. A semiconductor device made using this method is also disclosed.

1 . A method of detecting the breakdown potential of a semiconductor device having a thin dielectric layer, the method comprising: 
 measuring a spectroscopy of at least one selected area of the thin dielectric layer; and    determining whether the spectroscopy of the at least one selected area of the thin dielectric layer exhibits the presence of at least one breakdown precursor from the group consisting of H 2 , H interstitial radical, H attached radical, and H attached dimer.    
   
   
       2 . The method according to  claim 1  further comprising applying a substantially significant applied electric field across the at least one selected area of the thin dielectric layer while measuring the spectroscopy of the at least one selected area of the thin dielectric layer.  
   
   
       3 . The method according to  claim 2  further comprising: 
 increasing the substantially significant applied electric field across the at least one selected area of the thin dielectric layer by a predetermined amount after measuring the spectroscopy of the at least one selected area o the thin dielectric layer; and    determining whether the spectroscopy of the at least one selected area of the thin dielectric layer under the influence of the increased applied electric field exhibits the presence of at least one breakdown precursor from the group consisting of H2, H interstitial radical, H attached radical, and H attached dimer.    
   
   
       4 . The method according to  claim 2  further comprising: 
 repetitively increasing the substantially significant applied electric field across the at least one selected area of the thin dielectric layer by the predetermined amount after measuring the spectroscopy of the at least one selected area of the thin dielectric layer; and    for each repetitive increase of the substantially significant applied electric field, determining whether the spectroscopy of the at least one selected area of the thin dielectric layer under the influence of the increased applied electric field exhibits the presence of at least one breakdown precursor from the group consisting of H 2 , H interstitial radical, H attached radical, and H attached dimer.    
   
   
       5 . The method according to  claim 2  further comprising selecting the at least one selected area of the thin dielectric layer for measurement based upon the location of a leakage current in the semiconductor device.  
   
   
       6 . The method according to  claim 2  wherein measuring the spectroscopy includes the step of using Electron Spin Resonance Spectroscopy to measure the physical characteristics caused by the at least one selected from the group consisting primarily of Hydrogen ESR, Attached H ESR, Attached H dimer ESR and Si E and E′-center ESR.  
   
   
       7 . The method of  claim 6  wherein measuring the spectroscopy further includes the step of using infra-red spectroscopy to measure the physical characteristics caused by the at least one selected from the group consisting primarily of H 2 , attached H radical and dimer, and Si—O bond vibrations.  
   
   
       8 . The method according to  claim 7  wherein the infra-red spectroscopy is performed with a Raman Spectroscope.  
   
   
       9 . The method according to  claim 2  wherein measuring the spectroscopy includes the step of using Glancing Incidence X-Ray Reflection/Refraction (GIXR) to measure the physical characteristics caused by small spatial density changes in the interface (Metal/SiO2) region caused by the formation of the above H attached and radical states.  
   
   
       10 . The method according to  claim 2  wherein measuring the spectroscopy includes the step of using optical absorption, reflection, and transmission to measure the physical characteristics caused by the group consisting of attached H radical and dimer states.  
   
   
       11 . The method according to  claim 2  wherein measuring the spectroscopy includes the step of using X-ray Absorption Near Edge Structure (XANES) to measure small structural changes arising from the formation of the above H attached and radical states.  
   
   
       12 . The method according to  claim 2  wherein measuring the spectroscopy includes the step of using X-ray Absorption Fine Structure (XAFS) to measure small structural changes arising from the formation of the above H attached and radical states.  
   
   
       13 . A semiconductor device tested in accordance with the method of  claim 1 .  
   
   
       14 . A semiconductor device tested in accordance with the method of  claim 2 .  
   
   
       15 . A semiconductor device manufactured as part of a batch wherein a statistically representative sample from the batch is tested in accordance with the method of  claim 1 .  
   
   
       16 . A semiconductor device manufactured as part of a batch wherein a statistically representative sample from the batch is tested in accordance with the method of  claim 2 .  
   
   
       17 . A method for reducing dielectric breakdown of a semiconductor device having a thin dielectric layer, the method comprising: 
 substituting an H2 molecule in at least one selected area of the thin dielectric area with a second molecule.    
   
   
       18 . The method of  claim 17  wherein the second molecule does not react with Si or O to form an undesired attached state.  
   
   
       19 . The method of  claim 17  wherein the second molecule is an inert gas having a molecular size approximating that of a Hydrogen atom.  
   
   
       20 . The method of  claim 17  wherein the second molecule is helium.  
   
   
       21 . The method of  claim 17  wherein substituting includes growing the at least one selected are in the presence of pressurized flowing He.  
   
   
       22 . The method of  claim 17  wherein substituting includes: 
 applying ultra-violet light to the at least one selected area; and    applying a pressurized He gas to the at least one selected area.    
   
   
       23 . The method of  claim 17  wherein substituting includes: 
 applying a substantially significant electric field to the at least one selected area; and    applying a pressurized He gas to the at least one selected area.    
   
   
       24 . The method of  claim 23  wherein the substantially significant electric field is a pulsed electric field.  
   
   
       25 . A semiconductor device made using the method of  claim 17 .  
   
   
       26 . A semiconductor device made using the method of  claim 18.