Manufacturing method of semiconductor device

Abstract

The transistor characteristics of a MIS transistor provided with a gate insulating film formed to contain oxide with a relative dielectric constant higher than that of silicon oxide are improved. After a high dielectric layer made of hafnium oxide is formed on a main surface of a semiconductor substrate, the main surface of the semiconductor substrate is heat-treated in a non-oxidation atmosphere. Next, an oxygen supplying layer made of hafnium oxide deposited by ALD and having a thickness smaller than that of the high dielectric layer is formed on the high dielectric layer, and a cap layer made of tantalum nitride is formed. Thereafter, the main surface of the semiconductor substrate is heat-treated.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]The present application claims priority from Japanese Patent Application No. JP2007-128692 filed on May 15, 2007, the content of which is hereby incorporated by reference into this application.TECHNICAL FIELD OF THE INVENTION[0002]The present invention relates to a technology for manufacturing a semiconductor device. More particularly, it relates to a technology effectively applied to the manufacture of a semiconductor device provided with a MIS (Metal Insulator Semiconductor) transistor having a gate insulating film formed to contain oxide whose relative dielectric constant is higher than that of silicon oxide (SiO2).BACKGROUND OF THE INVENTION[0003]In recent years, with the trend of scaling down the size of MIS transistors constituting a semiconductor integrated circuit, the thickness of a gate insulating film made of silicon oxide has been rapidly reduced. However, when the thickness of the gate insulating film is reduced to about 2 nm,...

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Benefits of technology

[0009]However, although an oxide film formed by the rapid heat treatment in the non-oxidation atmosphere has sufficient densification, such an oxide film has oxygen deficiency which can be one of the defect sites to cause the deterioration of transistor characteristics such as mobility. On the other hand, although an oxide film formed by the heat treatment in the oxygen atmosphere can suppress the oxygen deficiency in the heat treatment, oxygen diffuses in the oxide to reach a silicon substrate and form an interface silicon oxide layer, and as a result, the capacitance of an equivalent silicon oxide thickness is increased.

[0011]An object of the present invention is to provide a technology capable of improving the transistor characteristics of a MIS transistor provided with a gate insulating film formed to contain oxide whose relative dielectric constant is higher than that of silicon oxide.

[0012]Another object of the present invention is to provide a technology capable of achieving the high dielectric constant of an oxide film, the reduction of oxygen deficiency in the oxide film, and the suppression of the interface silicon oxide growth.

[0016]By this means, since the high dielectric layer is densified by the heat treatment at the step (b), the high dielectric layer with a high relative dielectric constant can be obtained. Also, since oxygen in the oxygen supplying layer is supplied to the high dielectric layer by the heat treatment at the step (e), the high dielectric layer in which the oxygen deficiency is reduced can be obtained. In other words, it is possible to obtain the oxide in which the high dielectric constant of an oxide film, the reduction of oxygen deficiency in the oxide film, and the suppression of the interface silicon oxide growth can be achieved.

[0017]Note that Japanese Patent Application Laid-Open Publication No. 2006-080133 (Patent Document 1) and Japanese Patent Application Laid-Open Publication No. 2006-310801 (Patent Document 2) do not describe the formation of the oxygen supplying layer for supplying oxygen to the high dielectric layer. Also, different from Japanese Patent Application Laid-Open Publication No. 2006-310801 (Patent Document 2), the cap layer is not used as an intermediate layer (so-called buffer layer) for preventing the trapping which occurs at an interface between a gate insulating film and a gate electrode, but it is used for preventing oxygen in the oxygen supplying layer from diffusing into the atmosphere opposite to the high dielectric layer. Since oxygen does not diffuse into the atmosphere owing to the cap layer, oxygen in the oxygen supplying layer is supplied to the high dielectric layer.

[0019]According to the embodiment, it is possible to improve the transistor characteristics of a MIS transistor provided with a gate insulating film formed to contain oxide whose relative dielectric constant is higher than that of silicon oxide.

Problems solved by technology

However, although an oxide film formed by the rapid heat treatment in the non-oxidation atmosphere has sufficient densification, such an oxide film has oxygen deficiency which can be one of the defect sites to cause the deterioration of transistor characteristics such as mobility.

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