JPH0324724A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To surely bury conductive material without necessitating special surface treatment on the bottom surface and the side wall of a connection hole, by arranging a substrate obliquely to the main axis of ECR plasma flow of etching gas, and selectively etching the conductive material deposited on the substrate with the plasma flow. CONSTITUTION:The following are simultaneously or alternately performed; process for depositing conductive material 4 on a substrate 1, and process for selectively etching the conductive material 4 with plasma flow 11, while the substrate 1 is arranged obliquely to the main axis 11a of the electron cycrotron resonance plasma flow 10 of etching gas. That is, the conductive material 4 directly exposed to the ECR plasma flow 11 of etching gas is selectively eliminated. On the other hand, the conductive material 4 deposited in the inside of a connection hole 3 is not etched and eliminated because of the shadowing effect of an interlayer insulating film 2, and deposition only is progressed. Thereby the elimination of a natural oxide film on the metal surface exposed on the bottom of the connection hole 3, the surface treatment containing the side wall, etc., are unnecessitated, and the conductive material 4 can be burried with excellent reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device having a multilayer wiring structure in which a conductive material is embedded in a contact hole opened in a glabellar insulating film on a substrate.

[Summary of the invention]

The present invention deals with the process of depositing a conductive material on a substrate having a contact hole opened in an interlayer insulating film, or alternately with this process, unnecessary conductive material is deposited on an interlayer insulating film other than the contact hole. The present invention relates to a method of manufacturing a semiconductor device, characterized in that a conductive material is selectively buried in a contact hole by performing a step of selectively etching and removing a conductive material using an electron cyclotron resonance (ECR) plasma flow of an etching gas.

[Conventional technology]

As the degree of integration of semiconductor devices such as LSIs progresses, the importance of multilayer wiring technology is increasing. Among these, the outer diameter of a contact hole opened in an interlayer insulating film on a substrate is becoming finer, and a larger aspect ratio of, for example, 1 or more is being used.

A typical method for filling this contact hole with a conductive material is selective CVD of a high melting point metal such as tungsten (1). This utilizes a reaction in which, for example, 67 tungsten fluoride (WFJ) as a source gas is selectively reduced on the surface of a metal such as silicon (Si) or aluminum (AI), and 1 is selectively reduced. It is.

In fact, it is difficult to select high-melting point metals due to the fact that they are deposited on parts other than the metal surface, and even on metal surfaces, due to differences in the material and surface condition. . In other words, if there was contamination or a natural oxide film on the underlying metal surface, the selectivity was significantly inhibited.

This situation will be explained with reference to FIG. 3, which is a cross-sectional view showing a state in which a conductive material is embedded in a contact hole using a conventional method.
This figure shows a case where a conductive material 4 made of a high melting point metal such as W is selectively grown in a contact hole 3 opened in an interlayer insulating film 2 on a substrate 1.

As seen here, in conventional selective CVD,
The conductive material 4a was partially deposited on the glabella insulating film 2, etc., resulting in a decrease in reliability and yield of the semiconductor device.

Therefore, with the intention of improving the selection ratio when selecting and lengthening a first-class high-melting point metal for the connection hole, surface treatment is performed on the surface of the St substrate and lower layer wiring exposed at the bottom of the connection hole, or on the inner wall of the connection hole. (For example, Proceedings of the 36th Spring 1989 Lectures of the Applied Physics Association, Lecture No. 3 p.
ZF-3 etc.).

[Problem to be solved by the invention]

In the conventional method described above, the diameter of the connection hole is reduced,
In addition, as the aspect ratio increases, it is not always possible to perform sufficient surface treatment, making it difficult to perform selective enhancement with excellent reliability.

Therefore, an object of the present invention is to apply special surface treatment to the bottoms and side walls of the contact holes in a method for manufacturing a semiconductor device having a multilayer wiring structure in which a conductive material is selectively buried in contact holes opened in an interlayer insulating film on a substrate. It is an object of the present invention to provide a method for reliably embedding a conductive material without causing any damage.

[Means to solve the problem]

The method for manufacturing a semiconductor device according to the present invention is characterized in that the following two steps (a) and (b) are performed simultaneously or alternately in a process chamber of an ECR plasma apparatus.

stomach. The process of depositing a conductive material onto a substrate.

The deposition method may be either conventional selective CVD or non-selective Plunket CVD.

This step uses the process chamber of the ECR plasma device as a reduced pressure CVD chamber, and does not directly use the ECR plasma generation function of the ECR plasma device.

B. A step of arranging the substrate obliquely with respect to the main axis of the ECR plasma flow of the etching gas, and selectively etching the conductive material deposited on the substrate in step A above by the ECR plasma flow of the etching gas.

The etching gas used in this step may be any gas that can provide a sufficiently large etching selectivity between the conductive material and the glabellar insulating film.

The angle at which the substrate is held diagonally with respect to the main axis of the ECR plasma flow is not particularly limited since the ECR plasma flow itself is not necessarily a parallel flow, but in order to achieve the purpose of the present invention, Approximately 10″C to 80°C
The angle is selected. At this time, the substrate may be fixed and held obliquely to the main axis of the ECR plasma flow, or the holding angle may be varied continuously or stepwise. Alternatively, the substrate may be rotated or rotated within the plane of the substrate while being held obliquely.

It is also possible to increase the deposition rate of the conductive material by providing a heating mechanism in the susceptor on which the substrate is placed in the process chamber of the ECR plasma apparatus, or by heating the substrate by lamp irradiation.

As a conventional technique similar to the above-mentioned means according to the present invention, there is a method of forming an insulating film with a good stepping force barrier on a substrate using an ECR plasma CVD apparatus (Japanese Patent Application Laid-Open No. 62-2011).
- Published in Publication No. 133725). The present invention uses an ECR plasma device as an etching means.
Low pressure CVD separately without direct connection with plasma generation means
It is clear that the purpose, means, and effect are different from those of the conventional example.

[Effect]

The conductive material is selectively or non-selectively deposited inside the connection hole opened in the interlayer insulating film on the substrate by the 1,000-stage step.

Next, the conductive material deposited on the interlayer insulating film and the like, which is directly exposed to the ECR plasma flow of the etching gas, is selectively etched away by the means port. On the other hand, the conductive material deposited inside the contact hole is not etched away due to the shadowing effect of the glabellar insulating film, and only the deposition progresses.

Since we use an etching gas that has a sufficiently high etching selectivity between the conductive material and the glabellar insulating film by the ECR plasma flow, it is unlikely that the glabellar insulating film will be etched and its thickness will be reduced or the profile of the connection hole will deteriorate. Not many.

Due to the above-described effects, it becomes possible to reliably embed the conductive material only inside the connection hole not only by selective CVD but also by non-selective blanket CVD.

Conventionally, when connecting holes with different depths on the same substrate are filled with a conductive material, a phenomenon has been observed in which when the deep connecting holes are sufficiently filled, the conductive material overgrows in the shallow connecting holes. However, according to the present invention, connection holes of different depths can be filled simultaneously and uniformly without causing such a phenomenon.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of an apparatus used in a method of manufacturing a semiconductor device according to an embodiment of the present invention. In the same figure, 2.4
The 5 GHz microwave is transmitted to E by the microwave waveguide 14.
Introduced into CR plasma chamber l6, magnet coil 15
Together with the approximately 900 Gauss magnetic field generated by this, the etching gas from the etching gas introduction hole 12 is turned into plasma. The plasma becomes an ECR plasma stream 11 and is introduced into the process chamber 17. Process chamber l7
is equipped with a CVD gas introduction hole l3 and an exhaust hole l9 connected to a vacuum pump (not shown).

A substrate 1, such as a silicon wafer, is held on a susceptor 18 that is disposed obliquely at a variable angle between approximately 10° C. and 80° C. with respect to the main axis 11a of the ECR plasma flow. The susceptor 18 is rotatable or rotatable within the plane of the substrate 1 with the substrate 1 placed thereon. Further, the susceptor l8 has a built-in resistance heater, for example, and can heat the substrate 1 to a desired temperature.

In the ECR plasma device configured as above,
In this embodiment, a method of selectively filling connection holes with a high-melting point metal of first grade will be explained.

FIGS. 2(a) to 2(C) are schematic process diagrams of a method for manufacturing a semiconductor device according to an embodiment of the present invention. In FIG. 1A, a contact hole 3 having a large aspect ratio is opened in an interlayer insulating film 2 made of silicon oxide (Sift) or the like on a substrate 1. As shown in FIG. This substrate 1 is placed on a susceptor 18 disposed obliquely at an angle of approximately 45 degrees with respect to the main axis 11a of the ECR plasma flow, and heated to, for example, 260 degrees Celsius.

From the etching gas introduction hole 12, sulfur hexafluoride (SF&
) is introduced for 50 seconds and turned into plasma by a 2.45 GHz microwave introduced from the microwave waveguide l4 and a magnetic field of about 900 Gauss from the magnet coil l5. The etching gas turned into plasma becomes an ECR plasma flow 11, is conducted into the process chamber 17, and is irradiated onto the substrate l. At the same time, CVD gas introduction hole l3
For example, tungsten hexafluoride (W
F&) for 10sec, silane (Sill4) for 6s
ecm, hydrogen (L) 1000scc as carrier gas
A mixed gas of a+ is introduced and evacuated from the exhaust hole 9 with a vacuum pump to set the inside of the process chamber 17 to, for example, 0.5 Torr.
Under a reduced pressure atmosphere of r, a selective length is formed in the connection hole 3 of the substrate l by selective CVD. The deposited H is SFb for the part directly exposed to the ECR plasma flow 1l.
Because it is immediately etched away by plasma,
As a result, as shown in FIG. 2(b), the conductive material 4 is deposited only in the shadow of the interlayer insulating film 2, filling the contact hole.

In this embodiment, if selective etching of H and ECR plasma etching are performed simultaneously while rotating or rotating the substrate 1 within its plane, the conductive material 4 can be embedded with good uniformity as shown in FIG. 2(C). becomes possible.

In the present invention, it is possible to embed the conductive material 4 in the connection hole 3 not only by selective CVD but also by non-selective blanket CVD. In this case, the selection CV mentioned above
According to the embedding method according to D, the substrate temperature is set to 450℃, for example.
It is achieved by maintaining the temperature at a high temperature of °C.

Of course, even in the selective CVD method, the selective growth ratio is insufficient and as described in the conventional example, the glabella insulating film 2? Even if the wiring material 4a is partially deposited on the contact hole 3, it is etched away by the ECR plasma flow 11, and selective filling into the contact hole 3 is ensured.

In the present embodiment, metal was used as the conductive material 4, but it is also possible to use aluminum (AI), polysilicon (p-Si), or the like. In the case of AI, triisobutylaluminum (TIBA) or trimethylaluminum (TM^) is used as a source gas, argon (Ar) is used as a carrier gas, and boron trichloride (BC13) or chlorine (CI■) is used as an etching gas. In the case of p-St, use SiH4 or disilane (SiJb) as the source gas and the same as the carrier gas.
silane tetrachloride (SiC) was used as the etching gas.
la) and CI. You can use [Effects of the Invention] As detailed above, according to the present invention, the inside of the fine connection hole with a large aspect ratio opened in the glabella insulating film on the substrate,
Conductive materials such as W 2 , AI or p-Si allow reliable and reliable implantation.

Regardless of the method of embedding the conductive material, selective CVD or non-selective Plunket CVD, the conductive material can be deposited only in the connection hole.

This eliminates the need to remove the natural oxide film on the metal surface exposed at the bottom of the connection hole and to treat the surface including the sidewalls, which were necessary to improve the selectivity when filling with conventional CVD. Therefore, it becomes possible to embed a conductive material with good reproducibility, and the present invention makes a significant contribution to the semiconductor device manufacturing process.

2.1.1.1...1 interlayer insulating film 3...1 connection hole 4 -------...1---1 conductive material 11----
-----------E CR plasma flow 11a-
...1...1 ECR plasma flow main axis 12--1--1 Etching gas introduction hole l3-1...
-・-C V D gas introduction hole 14-・1-11--・
1...-Microwave waveguide 1 6-------------
------E CR plasma chamber 17-----
・−・−Process chamber 18−−−−−・−−1−
-Susceptor

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an apparatus used in a method of manufacturing a semiconductor device according to an embodiment of the present invention, FIG. 2 is a schematic process diagram of a method of manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. FIG. 3 is a cross-sectional view showing a state in which a conductive material is embedded into a contact hole by a method. i 1-1・---・----...Group 1 anti-Figure 1 (a) (b) (C) Horse 2 figure

Claims (1)

[Claims] A method for manufacturing a semiconductor device in which a conductive material is selectively buried in a contact hole on a substrate, comprising: (a) depositing the conductive material on the substrate; (b) electron cyclotron resonance of an etching gas on the substrate; A step of performing selective etching of the conductive material by an electron cyclotron resonance plasma flow of the etching gas arranged obliquely with respect to the main axis of the plasma flow, and performing the two types of steps A and B above simultaneously or alternately. A method for manufacturing a semiconductor device, characterized by: