JP2706388B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device. More specifically, the present invention relates to a method for forming an electric conduction portion.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor elements, the diameter of a contact hole has been reduced, and the ratio of the depth to the diameter (aspect ratio) of the contact hole has been increasing. Then, it is becoming difficult to cover the inside of the contact hole with the wiring material.
As a solution to this problem, there has been a chemical vapor deposition method (hereinafter, referred to as a CVD method) of a refractory metal such as tungsten. In the whole surface growth method, after a contact layer such as Ti, TiW or WSix is coated in advance by a sputtering method, tungsten can be grown on the whole surface to fill the contact hole.

[0003]

When tungsten is to be grown by the whole surface growth method, necessary sputtering Ti or TiW is required.
The adhesion layer of, for example, WSix is used not only to make tungsten and the insulating film adhere to each other, but also to make Si
It is also indispensable as a barrier metal to suppress erosion of the substrate, but as the aspect ratio of the contact hole increases, the required amount of barrier metal is coated up to the bottom of the contact hole by a normal thin film formation method by sputtering. Things are getting harder.

[0004] In recent years, LSIs have been increasingly miniaturized, and the aspect ratio of contact holes has been increasing, so that the above problem cannot be ignored.

The present invention has been made in view of the above circumstances, and has as its object to provide a method of manufacturing a semiconductor device capable of uniformly filling a contact hole having a high aspect ratio.

[0006]

According to the present invention, an insulating layer having a thickness of 1 to 1.2 μm is formed on a silicon substrate, and the insulating layer is etched to form a contact hole having an aspect ratio of 3 or more. , TiW or Ti is sputtered at 0.08 to 0.12 μm. Next, a tungsten film that is dense and has no underlying Si erosion
After the entire surface is grown from 8 to 0.1 μm, tungsten is entirely grown and the contact is completely buried.
A method for manufacturing a semiconductor device is provided.

For example, N + Si, P
This is for inputting or outputting a signal to an element composed of + Si and WSix layers. The embedded blanket tungsten CVD method of the present invention may be performed under conditions known in the art. Dense tungsten as a barrier metal is obtained by heating a substrate placed in a CVD apparatus to 250 ° C. to 350 ° C. (lower temperature than the embedding condition) and converting WF ₆ and SiH ₄ to, for example, 30/24 to 30 / With a flow rate ratio of 16 and a pressure of, for example, 0.01 to 0.10 Torr (low pressure compared to the embedding condition), a thickness of 0.08 to 0.1 μm is usually deposited. The embedded blanket tungsten heats a substrate placed in a CVD apparatus to 410 ° C. to 450 ° C.,
WF ₆ and H ₂ are mixed, for example, at 450 / 65-520 / 80 sc
At a flow rate of 70 cm and a pressure of, for example, 70 to 90 Torr, a thickness of usually 0.4 to 0.7 μm is deposited to completely fill the contact hole. Next, tungsten on the insulating film is etched back to form a contact buried plug. After the formation of the tungsten plug, a wiring or the like is formed to manufacture a semiconductor device.

[0008]

When a contact hole is buried by the blanket tungsten method, a stacked layer of CVD tungsten and a sputtered metal having good step coverage is used as a barrier metal, so that a sufficient film thickness can be obtained as a barrier metal at the bottom of a high aspect ratio contact. This suppresses erosion of the underlying Si when the contact hole is buried by the tungsten method, and suppresses the occurrence of junction leak current. Good contact characteristics can be obtained in a high aspect ratio contact hole.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the following embodiments. A method of manufacturing a semiconductor device using the above-described method for embedding an SRAM contact will be described. As shown in FIG. 1A, a gate electrode 2 having a laminated structure of an element isolation region 1, a WSix layer 2B and a poly-Si layer 2A, an N + Si layer 3, and a P + Si layer 4 on a silicon substrate 12.
Is formed, an interlayer insulating film 5 having a thickness of 1.1 μm is formed.
Is deposited by a CVD method, the interlayer insulating film is etched by a photolithography method, and the N + Si layer 3 and P
A contact hole 6 is formed on the + Si layer 4 and the WSix layer 2B of the gate electrode 2. Each of the contact holes has a diameter of 0.3 μm and a depth of 1.1 μm on the N +, P + Si layer and the WSix layer. Next, the silicon substrate is immersed in 1% buffered hydrofluoric acid for 45 seconds to remove a natural oxide film on the device, and then a TiW layer 7 is deposited by a 0.1 μm sputtering method. (FIG. 1 (b)). Next, the deposition temperature 2
At 70 ° C., a pressure of 0.02 Torr, and flow rates of WF ₆ and SiH ₄ of 10 sccm and 8 sccm, respectively, 12
A 0.08 μm tungsten layer 8 is grown for 0 seconds (FIG. 1C). FIG. 2 is an enlarged view of a portion A in FIG. Subsequently, the substrate temperature was 430 ° C., the pressure was 80 Torr,
The flow rates of WF ₆ and H ₂ were set to 500 sccm and 75 s, respectively.
A tungsten layer 9 having a thickness of 0.6 μm is grown on the entire surface in 90 seconds at ccm (FIG. 1D). Subsequently, etch back is performed to remove tungsten and TiW on the interlayer insulating film. Is completed (Fig. 1
(E)).

When the barrier metal is formed only by sputtering, as shown in FIG. 3, when the contact hole is buried by the blanket tungsten method, the underlying Si is eroded (11: silicon) because the thickness of the contact bottom is insufficient. Erosion) and junction leaks occur.

[0011]

As described above in detail, according to the present invention, a good buried shape and good contact characteristics can be obtained in a contact hole having a high aspect ratio.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a manufacturing process of a semiconductor device showing a configuration of an embodiment of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG. 1 (c).

FIG. 3 is a cross-sectional view of a semiconductor device according to the related art.

[Description of Signs] 1 element isolation region 2 gate electrode 2A poly-Si layer 2B WSix layer 3 N + Si layer 4 P + Si layer 5 interlayer insulating film 6 contact hole 7 sputter TiW layer 8 CVD-tungsten layer (barrier metal) 9 CVD-tungsten layer (Embedded) 10 Embedded plug 11 Silicon erosion 12 Silicon substrate

Claims (1)

(57) [Claims] An insulating layer is formed on a silicon substrate, and the insulating layer is etched to open a contact hole.
After sputtering high melting point metal of Ti or Ti alloy ,
Blanket CVD-Tungsten using WF ₆ and SiH ₄
The coverage is better tungsten than sputtered film confluent as a barrier metal in low temperature and low pressure conditions than embedding conditions of tungsten by ten method, followed by embedding the tungsten by the blanket <br/> Tsu preparative CVD- tungsten method, a wire A method for manufacturing a semiconductor device, comprising: forming a semiconductor device;