Semiconductor device and manufacturing method thereof

Abstract

An insulating layer is formed on a semiconductor substrate, and has a through hole for via. A porous silica layer has a trench for interconnection communicating to the through hole for via, and is formed on the insulating layer in contact therewith. A conductive layer is formed in the through hole for via and in the trench for interconnection. The insulating layer is formed from a material containing carbon, hydrogen, oxygen, and silicon, and having absorption peak attributed to Si—CH3 bond in a range from at least 1260 cm−1 to at most 1280 cm−1 (around 1274 cm−1) when measured with FT-IR. Thus, a semiconductor device having a porous insulating layer in which depth of the trench for interconnection is readily controlled, a dielectric constant is low, and increase in leakage current is less likely, as well as a manufacturing method thereof can be obtained.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically showing a structure of a semiconductor device according to one embodiment of the present invention.

FIGS. 2 to 5 are schematic cross-sectional views successively showing the steps in a method of manufacturing the semiconductor device according to one embodiment of the present invention.

FIG. 6 is a cross-sectional view schematically showing another structure of a semiconductor device according to one embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view showing a manner of depositing three types of insulating layers on a wafer with CVD.

FIG. 8 is a schematic cross-sectional view showing a manner of annealing three types of insulating layers.

FIG. 9 shows a result of measurement of leakage current values before and after annealing for each of the three types of insulating layers.

FIG. 10 shows a result of measurement of a ratio between dielectric constant after annealing and dielectric constant before annealing (after annealing/before annealing) for each of the three types of insulating layers.

FIG. 11 shows a result of composition analysis before and after annealing for each of the three types of insulating layers.

FIG. 12 shows a result of measurement with FT-IR (in a range of wave number from 1500 to 5000 cm^{31 1}) before and after annealing for each of the three types of insulating layers.

FIG. 13 shows a result of measurement with FT-IR (in a range of wave number from 500 to 1400 cm⁻¹) before and after annealing of an insulating layer in Comparative Example 1.

FIG. 14 shows a result of measurement with FT-IR (in a range of wave number from 500 to 1400 cm⁻⁵¹) before and after annealing of an insulating layer in Comparative Example 2.

FIG. 15 shows a result of measurement with FT-IR (in a range of wave number from 500 to 1400 cm⁻¹) before and after annealing of an insulating layer in Example of the Present Invention.

Claims

1. A semiconductor device, comprising: a semiconductor substrate;an insulating layer formed on said semiconductor substrate and having a through hole for connection; anda porous silica layer having a trench for interconnection communicating to said through hole for connection and formed on said insulating layer in contact with the insulating layer;said insulating layer being formed from a material containing carbon, hydrogen, oxygen, and silicon, and having absorption peak in a range from at least 1260 cm−1 to at most 1280 cm−1 when measured with Fourier transform infrared absorption spectroscopy.

2. The semiconductor device according to claim 1, wherein absorption peak of said insulating layer is attributed to Si—CH3 bond.

3. The semiconductor device according to claim 1, wherein said porous silica layer has an average pore diameter in a range from at least 1 nm to at most 10 nm.

4. The semiconductor device according to claim 1, wherein said insulating layer contains said carbon in an amount ranging from at least 10 atomic % to at most 40 atomic %.

5. A method of manufacturing a semiconductor device, comprising the steps of: depositing an insulating layer containing carbon, hydrogen, oxygen, and silicon on a semiconductor substrate by producing plasma of dimethyldimethoxysilane used as a raw material; andforming a porous silica layer by applying a coating liquid on a surface of said insulating layer followed by drying and annealing.

6. The method of manufacturing a semiconductor device according to claim 5, wherein said annealing is performed in an atmosphere containing oxygen.