JPH0411730A - Cvd method - Google Patents

Abstract

PURPOSE:To enable complete burying into a groove and uniform deposition onto a substrate having a large area by forming a silicon-containing layer by using organic silicon gas and hydrogen gas and forming reactive atoms by the discharge or a reactive gas. CONSTITUTION:The surface of a wafer 2 in a reaction vessel 1 is supplied with organic silicon gas A as it is, and hydrogen gas B and a reactive gas C are introduced into the vessel 1 by microwave discharge. TES(triethylsilane) is induced as the organic silicon gas, and hydrogen atoms formed by the discharge of the gas B are applied and a silicon-containing layer is formed on the surface of a substrate. A silicon reaction layer is shaped by reactive atoms formed by the discharge of the gas C. Laminated films are deposited by repeating such a CVD method. Accordingly, comformable CVD enabling complete burying into a groove and uniform deposition onto a substrate having a large area is realized, thus forming excellent various multilayer films.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a CVD method.

More specifically, the present invention relates to a novel CVD method useful as conformal CVD that enables complete filling in trenches and uniform deposition on large area substrates.

(Prior Art and its Problems) Various CVD (vapor phase reactive deposition) methods have been developed and have already been put into practical use for manufacturing semiconductors, LSIs, and other electronic devices. These C
The VD method is used not only in the manufacture of electronic devices but also in a wide range of technical fields as an effective method for various surface coatings and surface modifications.

The technology of these CVD methods is being vigorously improved, and with the development of industrial technology, further advances are required.

For example, recent technological advances in VLSI devices have been extremely rapid, and along with the progress toward higher integration, there has been the establishment of deposition technology in trenches with a large aspect ratio (depth of 7 widths), and the development of multilayer wiring technology. It is becoming necessary to improve the technique for embedding between An interconnects.

However, plasma CVD, which has been commonly used in the past, has the drawback that gaseous species are dominantly generated, and voids are inevitably generated.

In recent years, conformal CVD has attracted attention and is being studied as a method to eliminate such drawbacks and enable complete embedding. This conformaple CVD
As a result, attempts have been made to enable complete embedding using TE01 (tetraethyl oxy siren) 102 plasma and TEO8103 reaction, and in fact, surface migration caused in the gas phase by the TEOS/Os reaction has been It has been reported that conformal deposition is achieved because large multimers ((S i (OCi Hs )) are adsorbed uniformly on the substrate surface or, depending on the conditions, at the bottom of the grooves.

However, for these methods, T E OS
/Os system has practical difficulties in using ozone, and in the case of TEO810□ plasma system, T
As a result of the reaction between E01 and oxygen atoms, Si polymers are generated in the gas phase, and because these polymers have ethyl groups, they cannot be sufficiently oxidized by oxygen atoms, causing OH groups to form in the film. The remainder becomes moisture and desorbs when the temperature rises, resulting in volumetric shrinkage and unavoidable problems such as peeling and cracking of the film.

Moreover, in the case of the conventional methods, since TE01 contains oxygen and oxygen is used as a reactive gas, there is a restriction that only an oxide film can be formed. As insulating films used in "stud" capacitors, which are expected to become mainstream in DRAMs in the future, Si nitride films are also considered as well as Si oxide films, and this restriction on the types of films to be produced poses a technical hurdle.

This invention was made in view of the above-mentioned circumstances, and it is a T
It overcomes the drawbacks of the EOS/02 plasma method, etc., provides a high-quality film, and achieves conformal deposition when filling trenches.
The purpose of this invention is to provide a new conformal CVD method that is expected to spread to large-area display devices in the future.

(Means for Solving the Problems) In order to solve the above problems, the present invention introduces organic silicon gas and then irradiates hydrogen atoms generated by hydrogen gas discharge to form a silicon-containing layer on the surface of a substrate. The present invention also provides a CVD method characterized by forming a silicon reaction layer using reactive atoms generated by discharging a reactive gas.

The present invention also provides a digital CVD method characterized in that a laminated film is deposited by repeating the above CVD method.

More specifically, the CVD method of the present invention involves first reacting an organosilicon gas with hydrogen atoms, abstracting the hydrogen, depositing the resulting Si-containing polymer, and then depositing reactive atoms such as oxygen and nitrogen atoms. It is characterized by irradiating this with Si-reactive film such as oxide film or nitride film,
This step is repeated further, that is, the reaction is performed digitally to deposit a multilayer film. By this method, a)
- The film can be deposited layer by layer to achieve high quality, and even if it is thickly deposited, a high quality film can be obtained.

b) Depending on the conditions, it is possible to choose whether to deposit conformally (uniformly) within a deep groove or to deposit it at the bottom of the groove.
In either case, deep grooves can be buried and the surface can be flattened in the end.

For example, by depositing oxide films and nitride films alternately to a certain thickness, the film quality and pressure resistance can be improved.

e) By dispersing the deposition gas uniformly using a nozzle, etc., it is possible to deposit a film uniformly on large devices such as flat panels.
Application to other thin films such as a is also possible.

The type of organosilicon gas used as a raw material in this method is not particularly limited, and any organosilicon compound gas containing alkyl groups, alkoxyl groups, etc., and in addition halogen atoms, hydrogen atoms, etc. can be used.

This organosilicon gas is controlled to have a required flow rate together with hydrogen gas and reactive gas which are discharged into atomic form, and the hydrogen gas and reactive gas are controlled by means for discharging, For example, microwave discharge, high frequency discharge, and its conditions, such as voltage, degree of vacuum, etc., can be determined as appropriate.

As for the reactive gas, oxygen, nitrogen, ammonia, and various other gases can be used.

Hereinafter, embodiments of the present invention will be shown, and the structure of the present invention and its effects will be explained in more detail.

(Example) FIG. 1 of the attached drawings shows an example of a reaction apparatus that can be used in the CVD method of the present invention.

The organic silicon gas (A) is supplied as it is to the surface of the wafer (2) in the reaction vessel (1). On the other hand, hydrogen gas (B) and reactive gas (C) are introduced into the reaction vessel (1) by microwave discharge.

Next, an example of forming a 5iOz film using the second apparatus and introducing TES (triethylsilane) as the organic silicon gas will be specifically described.

First, a silicon-containing film was deposited on a wafer by causing a gas phase reaction with the TES introduced as it was by microwave discharge of hydrogen gas. Note that no reaction occurred even when hydrogen gas was directly introduced.

Figure 2 shows the TE of film deposition rate and step coverage (B/A).
It shows S concentration dependence. When the deposition rate was 40%, the deposition rate was maximum, the degree of step coverage was also very close to 1.0, and it was confirmed by SEM observation that the deposition was conformal.

Moreover, FIG. 3 shows the results of FT-IR measurement at each concentration. From the 40% waveform at which conformal deposition begins, peaks of 5iCzHs groups, CH3 groups, and CH2 groups, which were not observed at 20%, begin to appear. From this, the deposited species containing C has a large surface migration, which makes it possible to fill trenches with a large aspect ratio with an oxide film.

Next, in the reaction apparatus shown in FIG. 1, digital CVD was performed using the T ES / H2 plasma reaction followed by the <Ot plasma reaction at the pulse width shown in FIG. 4. That is, the process of adsorbing the above intermediate product onto the wafer and then oxidizing it with 02 radicals was repeated. The temperature of the wafer was 250°C, and 0□ radicals were generated by microwave (2,45GH2) discharge.

Figure 5 shows the deposition rate and X when changing the 02 pulse width.
This is the composition ratio determined from the PS measurement results.

This composition ratio was calculated by considering only the photoionization cross section.

The deposition rate decreases as the 02 pulse width increases. This is considered to be because the ethyl group bonded to Si is cut off by oxygen radicals. Furthermore, the composition ratio is close to that of a thermal oxide film.

FIG. 6 shows the deposition rate and composition ratio with respect to the reaction time of TES/Ht. It is shown that by controlling the reaction time, it is possible to perform a layer-by-layer deposition process of molecular layers.

FIG. 7(a) shows the FT-IR waveform of a Si oxide film formed by digital CVD using TES/H2+02 plasma. The peak of 5i-0 was steep, indicating that the film was of good quality. In the case of the conventional method of TEO8102 shown in FIG. 7(b), absorption of 5iC2Hs, which is an impurity peak, is observed.

The filling characteristics in the trench were also confirmed by SEM observation and the like to be conformal deposition.

Of course, the invention is not limited to the above examples. Various aspects are possible.

(Effects of the Invention) As described above in detail, the present invention realizes conformal CVD that enables complete embedding in trenches and uniform deposition on a large-area substrate. High-quality, heterogeneous multilayer films are also possible.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a reaction apparatus that can be used in the CVD of the present invention. FIG. 2 is a correlation diagram showing the relationship between TES concentration and deposition rate. FIG. 3 is a spectrum diagram showing the film composition of T ES / H2 plasma. FIG. 4 is a schematic diagram showing the supply pulses of TES/H2 and 02 in digital CVD. FIG. 5 is a correlation diagram showing the relationship between the 02 pulse width and the deposition rate. FIG. 6 is a correlation diagram showing the relationship between T ES / H2 reaction time and deposition rate. FIG. 7 is a spectrum diagram showing the composition of the produced film. 1... Reaction container 2... Wafer

Claims (2)

[Claims] (1) Introducing organic silicon gas, then irradiating hydrogen atoms generated by hydrogen gas discharge to form a silicon-containing layer on the substrate surface, and then silicon-containing layer by reactive atoms generated by reactive gas discharge. A CVD method characterized by forming a reaction layer. (2) A digital CVD method in which the method described in claim (1) is repeated to deposit a laminated film.