JPS6348846A - Thin film device and formation thereof - Google Patents

Abstract

PURPOSE:To prevent wire breakdown at a step part, defects due to electromigration accompanied by the increase in current density and short circuits between layers due to the yield of hillocks, by a laminated structure, in which metal layers are provided between Al layers including C. CONSTITUTION:The constitution of this device bas a laminated structure, in which, e.g., metal layers 5 are provided between Al layers 4. The concentration of C in the Al layer 4 is relatively high. The concentration of the C in the metal layer 5 is relatively low. In addition, an SiO2 oxide film 7, a contact hole 7a and a diffused layer 10 are provided in an Si substrate 6. A metal layer 9, whose concentration of C is relatively low, is provided between Al layers 8, whose concentration of the C is relatively high. Such a laminated structure is possible. The lower Al layer is in contact with the Si substrate 6. Si is introduced in the Al layers 8 so as to prevent the diffusion of Si in the substrate into Al.

Description

[Detailed Description of the Invention] [Summary] In order to solve the problem of the conventional device that cannot completely prevent hillocks (protrusions) in a thin film 4 and a method for forming the same, the present invention uses a carbon-containing A2 layer. The multilayer structure completely prevents hillocks.

(Industrial Application Field) The present invention relates to a thin film device, particularly A! ! , relates to a thin film device using a wiring film and a method for forming the same. In a thin film device, the A2 wiring film may be disconnected if electromigration or hillocks occur, so there is a need for a highly reliable thin film device that suppresses these phenomena and does not cause disconnection of the A2 wiring film.

[Conventional technology]

An IC is formed by forming elements on a semiconductor substrate and connecting them with metal wiring. In this case, with the development of highly integrated ICs, both element f and wiring tend to be miniaturized.
Limited to J.

[Problem that the invention seeks to solve]

Wiring films tend to be multi-layered as they become finer, which causes problems such as disconnections at step portions, defects due to electromigration due to increased current density, and short circuits due to the formation of hillocks. All of these are caused by the fact that the atoms of A tend to migrate, and even heat treatment alone without current flow causes migration and disconnection of the wiring film.

In order to eliminate the problem of hillock generation, conventionally, a thin film device having a multilayer structure with a metal layer 2 such as W or Ti interposed between the △2 layers 1 has been used, as shown in Fig. 5. Yes, but
Even with this method, there was a problem that hillocks could not be completely prevented. In addition, 3 in Figure 3 is S! 02 chukka membrane.

[Means for solving problems]

The device of the present invention has a W-layer structure in which a C-containing Af1 layer 4 is interposed with a gold Ii1 layer 5, as shown in FIG. 1', for example.

[Effect]

By forming the C-containing A2 layer 4 into a multilayer structure, hillocks are not generated.

〔Example〕

FIG. 1 shows a top view of an embodiment of the apparatus of the present invention.

In the figure, 4 is a double layer containing C, and the Ca content is set relatively high (10% to 20%). 5ha A Ill
, m It is a metal layer containing relatively low C11 degrees (0.1% or less). It has a multilayer structure in which a metal layer 5 is interposed between A2 layers 4. Note that the metal layer 5 has C on A2.
In addition to those containing Ti or W, the same metal layers as conventional ones may be used.

Here, a method of mixing C into Ae will be explained. A
When C is doped by ion implantation in the IFJ, C(7
) Although the specific resistance gradually increases with injection of 0.1% or more45
C precipitates during heat treatment at 0°C.

This is because C and AE are not in a bonded state, so the eigenlimit (0
, 1%) or more is thought to precipitate during heat treatment.

Therefore, as a result of gradually introducing C into the A2 film in a state where A2 and C are bonded, it has been found that no precipitation of C occurs even after heat treatment. However, in this case, the resistance increases exponentially when the C concentration exceeds a certain level, making it impossible to use it as a wiring.

FIG. 2 is a diagram showing the change in specific resistance when the C concentration (C/(A~+C)) in the bonded state is changed under conditions before and after heat treatment. As is clear from the figure, if the C concentration is 20% or less both before and after heat treatment, there is almost no increase in resistivity, and after heat treatment at 450°C, resistivity decreases by 1/2.
It turns out that it becomes 2.

As a result of X-ray measurement, it was found that the A2 film mixed with C had oriented microcrystals, and it is thought that C was present in the grain boundaries. Therefore, even during heat treatment, A2
Migration of UA particles is suppressed, so that crystal growth does not occur rapidly, and electromigration accompanying an increase in current density is also suppressed, and hillocks do not occur. In particular, no hillocks occur even during heat treatment at 600℃ (C
In the case of a film that does not contain any of the above, hillocks occur during heat treatment at 1,100°C, which is not the case with the conventional substrate film.

The present invention is also characterized by being microcrystalline with a tJ5 grain size of 1100 nm or less. In this case, C
The bonding state of the and AIl atoms was measured using an X-ray photoelectron analyzer, and it was confirmed that they were completely chemically bonded.

In addition, in the case of the present invention, the C temperature of the bottom layer 4 is not necessarily 20
It does not have to be less than %.

FIG. 3 shows a sectional view of a further embodiment of the device according to the invention. In the figure, 6 is a 3HI plate, 7 is a 5i02 arrangement film, 7a is a contact hole, and 10 is a diffusion layer.

8 is an A2 layer having a relatively high C concentration, 9 is a metal layer A having a relatively low iCm degree, and has a multilayer structure in which a metal layer 9 is interposed between the A2 layers 8. The lower Afl 18 is in contact with the S r m plate 6 . A2 layer 8
In order to prevent 3i of the substrate 6 from diffusing into A2,
St has been introduced.

This device also does not cause electromigration or hiccups for the same reason as the embodiment shown in the first figure.

Here, a method of forming npai shown in FIG. 3 will be explained. In FIG. 4 (Δ), 5i02ff17 is formed to a thickness of 7000 mm on the 3i plate 6 by thermal oxidation or CVD, and as shown in FIG. 4 (B), a contact forming part is opened and impurities are implanted. and activated by heat treatment,
A diffusion layer 10 is formed. First, as shown in FIG. 2B, 2000 A2 films 8 containing 15% carbon are formed by plasma CVD in a state of being bonded to the Al film.

The formation conditions were parallel plate plasma CVDvciH.
At a gas pressure of 2.3 Torr, R of 13.56 MHz
F plasma and trimethylaluminum (CH3
) 3A2-A mixture of gas and H2 diluent gas is introduced into the plasma to deposit A. Substrate temperature is 50-100
It is also necessary to maintain the temperature at a low temperature of °C in order to reduce the grain size of the crystals.

Further, in the A to C films that contact the Si substrate 6 at the contact portion, about 1 to 2% of Si is introduced in advance in order to prevent 3i of the substrate from diffusing into A2. The introduction method is trimethyl aluminum.

S to hydrogen gas! The plasma CVD method is performed by mixing Ht (silane) gas.

Both Si and C are included in the contact diffusion film mentioned above.
Further, after depositing the A layer 9 of 6,000 layers by CVD or sputtering, an AE-C-3i film 8 of 2,000 layers is formed by the same method as above (see Figure 1).
C)〉.

〔Effect of the invention〕

According to the present invention, hillocks can be completely prevented by forming two layers containing C into a multilayer structure, and accidents such as short circuits in the living room can be prevented.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of one embodiment of the device of the present invention, FIG. 2 is a carbon concentration versus resistance characteristic diagram, FIG. 3 is a cross-sectional view of another embodiment of the device of the present invention, and FIG. diagram forming the device;
FIG. 5 is a sectional view of an example of a conventional device. In the figure, 3.7 is a 5i02 oxide film, 4.8 is an A2 layer containing C, 5.9 is a metal layer, 6 is a 3i substrate, 7a is a contact hole, and 10 is a diffusion layer. , -N, Agent: Patent Attorney Igata -[ . ．． / '' -da (Kuaishi used bamboo one yiden resistance L1 -hj mouth 1 figure 2t9, Ritsuki Kudamamohi 2 廼 5-)) 4 Kufu) Kojizashito I〉Rino) Kikuni Carbon, & Kyo no Ju Ni Ura Kabuto Zeh Ueda Hiroshi La (q (A) (B) (C) Ki 3 illustration -) membrane mutter 5 form ↑ between the 4th figure 1/) Figure 5

Claims (7)

[Claims] (1) Aluminum layer (4, 8) containing carbon,
A thin film device characterized by having a multilayer structure with metal layers (5, 9) interposed therebetween. (2) The aluminum layer (4, 8) has a relatively high carbon concentration, and the metal layer (5, 9) has a relatively low carbon concentration. The thin film device according to scope 1. (3) The thin film device according to claim 1, wherein the aluminum layer (8) is provided at a contact portion with the Si substrate (6) and further contains Si. (4) The bottom aluminum layer (8) is the substrate (6)
3. The thin film device according to claim 1 or 2, wherein the thin film device is provided in a contact portion with. (5) The thin film device according to claim 3, wherein the uppermost aluminum layer (8) has a relatively high carbon concentration and covers the surface of the wiring. (6) When forming a thin film device having a multilayer structure in which carbon-containing aluminum layers (4, 8) are interposed with metal layers (5, 9), the method is characterized in that it is formed in plasma. Method for forming thin film devices. (7) Forming a thin film device in which aluminum layers (4, 8) containing relatively high carbon concentration are interposed with metal layers (5, 9) containing relatively low carbon concentration to form a multilayer structure. A method for forming a thin film device, characterized in that the film is formed in plasma.