JPH02130828A - How to form fine wiring - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming fine wiring, and particularly to a method for forming a thin film having a laminated structure and having good adhesion.

[Conventional technology]

In conventional methods for forming fine wiring, methods for improving the adhesion of the thin film include applying heat treatment immediately after forming the thin film or inserting another thin film.

[Problem to be solved by the invention]

The above-mentioned conventional technologies are all aimed at flat surfaces and contact structures between the surfaces, and do not take into consideration the mechanical structure or shape, resulting in the thin film formed peeling off during the LSI manufacturing process. There was a problem.

An object of the present invention is to improve the adhesion of the above-mentioned thin film.

[Means to solve the problem]

The above object is achieved by forming depressions or protrusions on the surface of the base on which the thin film is to be formed, and creating a structure for mechanically holding the thin film.

[Effect]

When a depression is formed on the surface of the base and a thin film is formed thereon, a part of the thin film is buried in the depression of the base. When the shape of the sidewall of the recess is perpendicular to the main plane of the semiconductor substrate, the thin film becomes difficult to peel off from the underlying surface due to the frictional force between the base material and the thin film material on this sidewall surface.
Adhesion is improved. Furthermore, when the sidewalls of the recesses have an inversely tapered shape, the properties can be significantly improved because peeling will not occur unless the underlying layer or the formed thin film is destroyed or greatly deformed in the vicinity of the recesses. Furthermore, even when protrusions are formed on the base surface, adhesion can be improved accordingly depending on the shape of the side walls of the protrusions.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1st
The figure shows a cross-sectional view of tungsten applied to LSI wiring.

The steps leading to FIG. 1 will be explained. First, a P-type Si substrate 1 is prepared, and a desired region of the main surface is selectively thermally oxidized to produce 5iO
A Z film 2 was formed, and then a phosphorus diffusion layer 3 was formed by phosphorus ion implantation and heat treatment. Next, the film thickness at the flat part is 0.8
A 5iOz4 film having a thickness of 5 μm was formed by a CVD method, and an opening was formed in the SiOz4 film by a dry etching method using a patterned photoresist as a mask.

Next, depressions 5 were formed on the surface of the thin film, which is an example of the present invention, to strengthen adhesion. This depression has a diameter of 0.5 μm
As a mask, a photoresist with a circular pattern of
0.2μ by dry etching method using CHFa gas
The depth was set to m. After removing the photoresist mask, 0.4μ of W was applied using DC magnetron sputtering.
m was formed.

Next, using the photoresist wiring pattern as a mask, W was processed by dry etching to form a W wiring pattern.

Next, a depression 7, which is an example of the present invention, was formed on the W surface.

The depressions 7 are formed by forming a photoresist pattern using the same photolithography process as that used to form the depressions 5, and by dry etching using SFe gas to a depth of 0.1 μm.Then, the photoresist used as a mask is removed. After that, an insulating film 8 was formed.

A cross-sectional view of this state is shown in FIG. Hollow 7 shown here
In forming the recesses 7, the recesses 7 may be formed after processing the W wiring as described above, or the recesses 7 may be formed by changing the processing order and the W layer 6 may be processed into the wiring pattern. A similar effect was obtained by forming .

Next, the relationship between the density of the depression and the critical load in the adhesion evaluation test is shown using FIG. Recesses each having a thickness of 5 pm and a depth of 0.15 μm were formed at different densities, and a W film having a thickness of 0.4 μm was formed thereon by sputtering. The critical load was 0.50 kgw when the density of the hollow was IC) m″″2, but when the density of the hollow was 50 m″2100+nm−”, the critical load was 0, respectively.
They were 57 kgv, 0, and 72 kgv. ! If the density is 500 mm-2 or more, the measurement limit (1, kgw)
That was it. It can be seen that as the density of the bells increases, that is, as the number of depressions increases, the adhesion improves.

Next, the critical load when the composition ratio X of the CVD-WSiX film is changed will be explained using FIG.

Two types of depressions were prepared, and samples were prepared that had a vertical to approximately 10@reverse taper and a vertical depression.

Comparison was made with one without dents. The sample has a depression density of 108
C V D Si O with a recess shaped like “am-”
0.4 μm of CVD-WSix was deposited on Z. The larger the composition ratio X of CVD-WSix, that is, the more Si-rich the film, the larger the critical load and the better the adhesion. When the composition ratio
On S i Oz, the critical load was 100 gw (curve C), whereas it rose to 680 gw for the sample with vertically shaped depressions (curve b). For the sample with a reverse taper of approximately 10° from the vertical (curve a), the value is even larger, 81
0 gw was measured. Regardless of the value of
It can be seen that the adhesion is good.

Next, the measurement results of the adhesion of W when protrusions are formed on the insulating film will be explained using FIG. For the sample, 0.6 μm CVD-8iOz was formed on a 4-inch Si substrate,
CVD 5iOz using photoresist as a mask.
A cylindrical protrusion with a height of 0.15 μm was formed by 15 μmz cutting.

Vertical and reverse tapered protrusions were formed by changing the dry etching conditions of CVD SiOz. The diameter of the protrusion is 0
．． It was set to 5 μm.

A on the horizontal axis in Fig. 4 indicates CV D after forming 0.4 μm W.
-S i Oz is deposited to a thickness of 0.6 μm.

The adhesion between the C V D -S i Oz film on which protrusions were formed and the W film was evaluated based on the critical load value of the squeeze test.

B is the state after further N2 annealing at 600°C for 30 minutes from state A, C is the state after forming 0.15 μm thick TiN from state B, and D is 0.9 μm from state C.
E shows the state after forming AQ of m, and E shows the state after annealing in Ht at 450° C. for 30 minutes from state D. As each process progresses, a slight decrease in critical load is observed.
It can be seen that the adhesion has decreased.

FIG. 4 is a plot for the case where no protrusion is formed (curve C), the case where a vertical protrusion is formed (curve b), and the case where a reversely tapered protrusion is formed (curve a). It was found that adhesion was improved by forming protrusions, and that adhesion was further improved by making the protrusions tapered.

Next, another example will be described. FIG. 5 is a cross-sectional view of the process of forming unevenness on 5iOz and forming tungsten wiring in close contact with this 5iOz.

On the surface of the insulating film 5iOz2 formed on the Si substrate 1,
A solution containing a mixture of resist and coating silicon compound (SOa) in a volume ratio of approximately 1=1 was applied to a film thickness of approximately 0.5 μm at 5 iOz.
Apply it on Z, etch the SOG with diluted hydrofluoric acid solution,
A cross section of the dried product is shown in FIG. 5a. A SEM photograph of the surface in this state is shown in FIG.

The sample in Fig. 5a is treated in oxygen plasma for 2 minutes to etch a part of the resist, forming an island-like resist on 5iOz2, as shown in Fig. 5. 0.1μ by plasma etching using
FIG. 5C shows a cross section after etching m5ioz and removing the resist 3 used as a mask. Film thickness 0.6μ
FIG. 5d is a cross-sectional view of a state in which tungsten is formed by sputter deposition on Si22 with 0.1 .mu.m unevenness formed on the surface of tungsten. As a result of evaluating the tungsten adhesion of the sample in this state, the critical load was 680 gw, which was significantly improved as compared to 360 g%l when no unevenness was formed.

Although the W wiring and the WSix wiring have been described above, similar effects can be obtained even if high melting point metals other than W or compounds of these metals are used as the wiring material. As can be seen from the above embodiments, the shape of the depressions and protrusions is most effective when they are inverted tapered, and the dimensions are determined by taking into account the underlying material, the thickness of the thin film to be formed, the pattern of the thin film, etc. The formation of depressions and protrusions is
In addition to the examples described above, processing techniques using etching gas or etching liquid can be applied depending on the liquid etching material.

〔Effect of the invention〕

According to the present invention, the adhesion of the thin film can be significantly improved, so that in the field of LSI manufacturing, the incidence of defects due to peeling of the thin film can be significantly reduced. Further, according to the present invention, the restrictive conditions regarding stress and distortion of the laminated thin film during the manufacturing process can be relaxed, so that it has the effect of improving economy and efficiency.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a tungsten wiring according to an embodiment of the present invention, Fig. 2 is a measurement diagram showing the relationship between pain and critical load of a W thin film formed on 5 ins. A measurement diagram showing the relationship between X of S i x and critical load,
Fig. 4 is an explanatory diagram of the transition of critical load showing the adhesion between S↓O2 and W in the LSI wiring process, Fig. 5 is a sectional view for explaining the process of an embodiment of the present invention, and Fig. 6 is a scanning electron micrograph showing the shape of a sample surface structure in an example of the present invention. DESCRIPTION OF SYMBOLS 1... Si substrate, 2... Si thermal oxide film, 3... Phosphorus diffusion layer, 4... Interlayer insulating film 1.5... Recess formed in interlayer insulating film 1, 6... Tungsten wiring, 7...
- Hollow formed in tungsten wiring, 8... interlayer insulating film 2.9... resist. 3rd barrier 2nd mouth 4 Figure 7 2nd degree (Ikubori t Stk handling 5LI-Rebellion SL□z Tank "Stenno L Dust b Niss Otsu O2

Claims (1)

[Scope of Claims] 1. A method for forming fine wiring, which comprises forming a thin film after forming depressions or protrusions on the surface of a base when laminating thin films in close contact with each other. 2. When forming depressions or protrusions on the base surface, a liquid containing solid or liquid particulate matter is applied to the base surface, a pattern of the above-mentioned particulate matter is formed on the base surface, and the particulate matter pattern is masked. 2. The method for forming fine wiring according to claim 1, further comprising the step of etching the surface of the base as a step. 3. The method for forming fine interconnects according to claim 1, wherein when forming the depression or protrusion on the surface of the base, the surface of the base is etched using a resist pattern as a mask. 4. The method for forming fine wiring according to claim 3, further comprising the step of applying a mixture of a resist and a silicon compound for coating (SOG) to the underlying surface when forming the resist pattern. 5. A method for forming fine wiring, which comprises irradiating the resist with light, X-rays, or electron beams when forming the resist pattern. 6. The depth of the formed depression or the height of the protrusion is 0
．． 2. The method for forming fine wiring according to claim 1, wherein the thickness is 0.1 μm or more and less than the thickness of the thin film formed on the base. 7. Claims 1 to 6, characterized in that at least one of W, Mo, tungsten silicide, titanium silicide, TiW, TiN, Al, and Cu is used as the thin film.
The method for forming fine wiring described in Section 1. 8. The method for forming fine wiring according to any one of claims 1 to 7, characterized in that a CVD method or a sputter deposition method is used when forming the thin film.