JP2647842B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device.

[Conventional technology]

A self-aligned contact formation method is used as one of the high integration techniques for semiconductor devices. However, a punch-through (alloy spike) caused by an interaction between a silicon substrate and an aluminum electrode is a shallow area required for high integration. A method of contacting an electrode through a barrier metal layer such as titanium nitride has been used to prevent the occurrence of penetration due to bonding.

In a conventional method for manufacturing a semiconductor device, a diffusion region of the opposite conductivity type is formed on a semiconductor substrate of one conductivity type, and an insulating layer covering the surface of the semiconductor substrate is formed. Next, a titanium layer is formed on the entire surface after providing a contact opening in the insulating layer on the diffusion region, and heat treatment is performed to form a titanium silicide in a region of the opening that is in contact with the surface of the diffusion region exposed. Material layer,
The titanium layer on the insulating layer is removed by an etching method. next,
Titanium is sputtered in a nitrogen atmosphere by a reactive sputtering method to form a titanium nitride layer on the entire surface, and after the aluminum layer is formed on the titanium nitride layer, the aluminum layer and the titanium nitride layer are selectively etched. An interconnect is formed to contact the diffusion region.

In another example of forming the titanium nitride layer, after forming the titanium silicide layer, the semiconductor substrate is heat-treated in a nitrogen atmosphere to form a titanium nitride layer on the surface of the titanium silicide layer.

[Problems to be solved by the invention]

In the conventional method of manufacturing a semiconductor device described above, when the titanium nitride layer is formed by the reactive sputtering method, the composition of TiNx varies depending on the partial pressure of the nitrogen gas and the argon gas, and controllability is difficult. Further, a process of forming a wiring by applying an aluminum layer after applying a titanium nitride layer on the entire surface is performed. However, there is a problem in that the titanium nitride layer is difficult to dry-etch and it is difficult to form fine wiring. In addition, the method of heat-treating a titanium silicide layer in a nitrogen atmosphere to form a titanium nitride layer on the surface has a problem that the reaction becomes non-uniform depending on the surface state and the reproducibility is deteriorated.

An object of the present invention is to provide a method of manufacturing a semiconductor device in which a barrier metal layer for preventing penetration is formed with good reproducibility.

[Means for solving the problem]

The method of manufacturing a semiconductor device according to the present invention includes the steps of: forming a reverse conductivity type diffusion region on one main surface of a one conductivity type semiconductor substrate; and forming an insulating layer on a surface including the diffusion region. Forming an opening in the insulating film, depositing a titanium layer on the insulating film including the diffusion region exposed to the opening, performing heat treatment, and forming a titanium layer in a portion in contact with the surface of the diffusion region. Forming a silicide layer; etching and removing the unreacted titanium layer; implanting nitrogen ions into the surface of the titanium silicide layer; and heat-treating the surface of the titanium silicide layer. And a step of depositing and patterning a metal layer on a surface including the titanium nitride layer to form a wiring electrically connected to the diffusion region.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

1 (a) to 1 (c) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining one embodiment of the present invention.

First, as shown in FIG. 1A, a field insulating layer 2 for element isolation is formed on one main surface of a silicon substrate 1 of one conductivity type to form an element formation region, and a surface of the element formation region is formed. A gate electrode 4 is formed via a gate insulating layer 3 and a source region 5 and a drain region 6 are formed by introducing a reverse conductivity type impurity into the silicon substrate 1 using the gate electrode 4 and the field insulating layer 2 as a mask. . Next, the silicon substrate 1
An insulating layer 7 is formed on the entire surface of the substrate, and an opening 8 for forming an electrode is formed in the insulating layer 7 on the source region 5 and the drain region 6.

Next, as shown in FIG. 1B, the surface of the source region 5 and the drain region 6
About 1000 mm of titanium layer is deposited by sputtering.
A heat treatment at about 600 ° C. is performed in nitrogen to form a titanium silicide layer 9 to a thickness of about 2000 ° at a portion where the surface of the source region 5 and the drain region 6 of the opening 8 is in contact with the titanium layer. Next, the titanium layer on the insulating layer 7 is removed with an etchant of H ₂ O ₂ + NH ₄ OH.

Next, as shown in FIG. 1C, nitrogen ions are implanted at an acceleration energy of 30 keV and a dose of 1 × 10 ¹⁶ cm ⁻² .
From the projection range at this time, nitrogen is introduced to a depth of several hundred degrees from the surface. Next, a heat treatment at about 900 ° C. is performed to form a titanium nitride layer 10 on the surface of the titanium silicide layer 9, and an aluminum wiring 11 connected to the titanium silicide layer 9 is selectively formed.

〔The invention's effect〕

As described above, according to the present invention, an opening is formed in an insulating film provided on the surface of a diffusion region, and a titanium silicide layer is formed only on the surface of the diffusion region exposed to the opening, and then nitrogen ions are formed. By forming a titanium nitride layer on the surface of the titanium silicide layer by ion implantation, a barrier layer is formed only in the opening, eliminating the need for a patterning step of the titanium nitride layer that is difficult to etch, and facilitating fine wiring. This has the effect of being able to be formed into

Further, by controlling the dose of nitrogen ions, the composition ratio of Ti and N in the titanium nitride layer can be easily controlled to a desired value, and the titanium nitride layer can be formed with good reproducibility.

[Brief description of the drawings]

1 (a) to 1 (c) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Field insulating layer, 3 ... Gate insulating layer, 4 ... Gate electrode, 5 ... Source region, 6
... Drain region, 7... Insulating layer, 8.
... titanium silicide layer, 10 ... titanium nitride layer, 11 ... aluminum wiring.

Claims (1)

(57) [Claims] A step of forming a diffusion region of a reverse conductivity type on one principal surface of a semiconductor substrate of one conductivity type; forming an insulating layer on a surface including the diffusion region; Forming a hole and exposing the surface of the diffusion layer, and depositing a titanium layer on the insulating film including the diffusion region exposed to the opening and performing a heat treatment to contact the surface of the diffusion region. Forming a titanium silicide layer in the portion where the titanium silicide layer is present, etching the unreacted titanium layer, removing the unreacted titanium layer, implanting nitrogen ions into the surface of the titanium silicide layer, and heat-treating the surface of the titanium silicide layer. A step of forming a titanium nitride layer on the substrate, and a step of depositing and patterning a metal layer on a surface including the titanium nitride layer to form a wiring electrically connected to the diffusion region. Manufacturing method.