| 摘要 |
PURPOSE:To increase capacitor density by improving the controllability of a Ta2O5 film thickness and thus decrease leakage current by a method wherein the Ta2O5 of high content of N and that of low content are superposed on a Si substrate via a Si3N4 ultrathin film. CONSTITUTION:The Si3N4 ultrathin film 2 is formed by treating the N type Si substrate 1 in NH3 at 1,200 deg.C, N2 is introduced into Ar+O2 for a fixed time with the Ta2O5 as the target, the Ta2O5 film 3 of high content of N is provided by high frequency sputtering method; when the Ta2O5 film 4 of low content of N is formed by stopping the introduction of N2, the rate of thermal expansion of the film 3 becomes at the value of medium between those of the film 4 and the Si substrate, and the stress due to the difference of the rates of thermal expansion is relaxed, accordingly the leak current in the Ta2O5 film is decreased. Since large content of N produces small dielectric constant, the film 3 is formed as thin as possible. Next, treatment is performed in dry O2 at 500 deg.C, thus decreasing the shortage of O in non stoichiometrical respect in the film 5 and blocking the formation of a conductive Ta4Si5, and accordingly leak is decreased. Finally, an Al electrode 8 is laid, and annealing is performed in N2, resulting in completion. |
