Semiconductor device having a stacked capacitor

Abstract

A stacked capacitor in a memory cell has a bottom electrode made of a metal or metal compound, a capacitor insulation film and a top electrode made of a metal or a metal compound. The capacitor insulation film includes an aluminum oxide film having a thickness of 2 to 4 nm and in contact with the bottom electrode, and an overlying hafnium oxide film having a thickness of 3 to 6 nm. The stacked capacitor has a higher resistance against a biased temperature test.

Description

BACKGROUND OF THE INVENTION [0001] (a) Field of the Invention [0002] The present invention relates to a semiconductor device having a stacked capacitor and, more particularly, to a technique for reducing dimensions of a semiconductor device having a stacked capacitor while assuring a higher capacitance of the stacked capacitor. The present invention also relates to a method for manufacturing such a semiconductor device. [0003] (b) Description of the Related Art [0004] Semiconductor devices have been developed to reduce the dimensions and increase the scale and functions thereof. In particular, DRAM devices now on the market have a capacity of giga-bit order with a reduced design rule of 110 nm (F110-rule), and next-generation DRAM devices will have such an order of capacity with a further reduced design rule of 90 nm (F90-rule). In such a development of finer design rule, a stacked capacitor used in each memory cell of the DRAM device also has reduced dimensions, which makes it diff...

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Benefits of technology

[0008] The present inventor noticed aluminum oxide in the study for achieving a thin capacitor insulation film in the stacked capacitor. Use of the aluminum oxide obviates a heat treatment for achieving a lower leakage current and thus provides a smaller thickness as small as 1 nm or smaller for the low-dielectric-constant film, which is generally formed on a silicon surface by oxidization thereof. This allows the capacitor insulation film to have a smaller thickness by 2.5 nm or more compared to the case of using the tantalum oxide as the capacitor insulation film.

[0010] In view of the above, it is an object of the present invention to provide a semiconductor device including a stacked capacitor having a capacitor insulation film, which is capable of suppressing degradation of the characteristics in the capacitor insulation film and suppressing increase in the leakage current generally caused by the BT test of the semiconductor device.

[0016] In accordance with the semiconductor device of the present invention and the semiconductor device manufactured by the method of the present invention, due to obviation of the heat treatment for reducing the leakage current in the aluminum oxide film, the aluminum oxide film is free from a low-dielectric-constant material and thus provides a higher capacitance to the stacked capacitor. In addition, the metal or metal compound of the bottom electrode prevents the aluminum oxide film from generating a depletion layer in the adjacent bottom electrode to thereby suppress degradation of the capacitor insulation film and thus improve the reliability of the capacitor after a BT test.

Problems solved by technology

In such a development of finer design rule, a stacked capacitor used in each memory cell of the DRAM device also has reduced dimensions, which makes it difficult for the stacked capacitor to have a required capacitance.

However, in the F90-rule DRAM device, it is difficult to use the HSG structure due to the finer design rule, wherein the polysilicon bottom electrode is not allowed to have the HSG structure because of the difficulty in formation of the hemispherical grains on the surface thereof.

However, the tantalum oxide has a problem of occurring of silicon oxynitride film having a lower dielectric constant, after the silicon electrode reacts with an adjacent tantalum oxide film in a heat treatment conducted for reducing a leakage current in the capacitor.

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