Method of producing semiconductor device and semiconductor device

Abstract

In the production of a semiconductor device in which a ferroelectric capacitor is used as a memory, a method of producing the semiconductor device in which the oxidation of a tungsten film embedded in an alignment mark prepared in the form of a groove is prevented includes forming an oxidation-preventing film composed of P—SiN (SiON) to cover the tungsten film prior to the formation of the ferroelectric capacitor, and heat-treating the oxidation-preventing film so as to thermally contract the film in advance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematic cross-sectional views of the relevant part of a first embodiment of the present invention;

FIGS. 2A and 2B are schematic cross-sectional views of the relevant part of a second embodiment of the present invention;

FIGS. 3A to 3C are schematic cross-sectional views of the relevant part of a third embodiment of the present invention;

FIGS. 4A and 4B are schematic cross-sectional views of the relevant part of a fourth embodiment of the present invention;

FIG. 5A is a schematic cross-sectional view of an example of a known FRAM;

FIGS. 5B and 5C are cross-sectional images of an example of the known FRAM; and

FIGS. 6A and 6B are images each showing a state of the oxidation of an alignment mark.

Claims

1. A method of producing a semiconductor device having a ferroelectric capacitor used as a memory and an alignment mark prepared in a form of a groove, comprising the steps of: embedding a tungsten(W) film in the groove of the alignment mark;forming an oxidation-preventing film composed of P—SiN (SiON) to cover the tungsten film; andperforming heat-treatment on the oxidation-preventing film so as to thermally contract the oxidation-preventing film prior to the formation of the ferroelectric capacitor.

2. A method of producing a semiconductor device as claimed in claim 1, further comprising the steps of: performing etch back so as to remove a part of the tungsten(W) film at the groove peripheral part of the alignment mark.

3. A method of producing a semiconductor device having a ferroelectric capacitor used as a memory and an alignment mark prepared in a form of a groove, comprising the steps of: depositing the tungsten(W) film in the groove of the alignment mark;polishing the tungsten(W) film by CMP to remove the tungsten(W) film outside of the alignment mark;forming an oxidation-preventing film composed of P—SiN (SiON) to cover the tungsten film;polishing the oxidation-preventing film by CMP to remove oxidation-preventing film outside of the alignment mark; andforming an oxidation-preventing film composed of P—SiN (SiON) to cover the tungsten film prior to the formation of the ferroelectric capacitor.

4. A method of producing a semiconductor device having a ferroelectric capacitor used as a memory and an alignment mark prepared in a form of a groove, comprising the steps of: depositing the tungsten (W) film in the groove of the alignment mark;polishing the tungsten (W) film by CMP to remove the tungsten (W) film outside of the alignment mark; andembedding an SOG film in the groove of the alignment mark.

5. A method of producing a semiconductor device as claimed in claim 1, wherein the oxidation-preventing film is a high-density plasma film.

6. A method of producing a semiconductor device as claimed in claim 1, further comprising a step of: performing a plasma treatment using N2 or N2O in the range of 200° C. to 450° C. on the oxidation-preventing film.

7. A method of producing a semiconductor device as claimed in claim 1, wherein the oxidation-preventing film is formed by using SiH4 or N2O gas.

8. A method of producing a semiconductor device as claimed in claim 1, further comprising a step of: forming a oxide film composed of P—SiO after forming an oxidation-preventing film composed of P—SiN (SiON),wherein a range of refraction index of the oxide film is from 1.45 to 1.65.

9. A method of producing a semiconductor device as claimed in claim 1, further comprising a step of: forming a hydrogen-diffusion-preventing film composed of Al2O3.