JPS6240364A - Formation of high melting point metal silicide - Google Patents

Abstract

PURPOSE:To form high m.p. metal silicide having uniform and low resistance and excellent self-matching characteristic by executing vapor deposition and ionization under specific conditions in the stage of heating a substrate having a silicon layer under specific conditions so that a high-purity metal is deposited by evaporation thereon. CONSTITUTION:The substrate having the silicon layer on at least the surface is heated to the temp. at which tetragonal MoSi2 and WSi2 are respectively formed with Mo and W, the temp. at which hexagonal VSi2, NbSi2 and TaSi2 are respectively formed with V, Nb and Ta and the temp. at which rhombic TiSi2, ZrSi2 and HfSi2 are respectively formed with Ti, Zr and Hf, then these high m.p. metals are deposited by evaporation on the substrate in the stage of depositing the high m.p. metallic films on the substrate. In this stage, >=10% of the vapor deposition particles are ionized for the formation of the first several tens Angstrom film or below and the ionized vapor deposition particles are accelerated to >=0.1keV to execute the vapor deposition. The vapor deposition is then continued in the non-ionizing stage until the desired film thickness is attained to generated the silicidation reaction simultaneously with the vapor deposition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming a high melting point metal silicide to be used as wiring or electrodes in a semiconductor device.

(Prior art) In recent years, semiconductor devices such as silicon integrated circuits have become increasingly popular.
In recent years, efforts have been made to increase density and speed by miniaturizing element dimensions. With such miniaturization, problems have arisen, such as delays in signal propagation due to increased resistance of polycrystalline silicon and diffusion layers, which have conventionally been frequently used as luminous poles and wiring. As a method to solve this problem, a method has been proposed in which high-melting-point metal silicide with excellent heat resistance is formed on the polycrystalline silicon or the diffusion layer to achieve low resistance. In particular, MI8 (Metal In5ul a) with minute dimensions
torSem1 conductor ) type field effect transistors have a so-called polycide electrode in which a high melting point metal silicide is formed on top of a polycrystalline silicon gate arrangement, and a high melting point metal silicide is formed on top of an impurity doped layer that is to constitute the source and drain. Silicided source/drain electrodes are being considered.

Refractory metal silicide can be formed by depositing a high melting point metal and silicon simultaneously and then performing high temperature annealing to form a silicide, or by depositing a high melting point metal on the surface of silicon and then annealing. A method of forming silicide (thermal annealing method) is being used.

(Problems to be Solved by the Invention) The electrical resistance of the silicide thin film formed by the conventional method described above has a drawback that it is large compared to the bulk value. for example,
□Siri size by uneven force (S, PLM... old...)
Fore VLSI Applications (Silic
ides for VLSI Applications
ns(New York Academic Pres.
s, 1983)) p, 30-31, in the case of MoSi2 the bulk resistivity is ~20
In contrast to the μΩ・bode, the U
The value of the membrane is low at 100-150 μΩ @ CIIL.

Thickness #i of the silicide layer used for lowering resistance,
In order to form a shallow b source/drain junction and to reduce the influence on the underlying silicon layer, it is desirable to reduce the thickness to about 1000A or less. Mo by conventional forming method
In Six, even when a film thickness of 1000 A is used, the sheet resistance is as high as 10 to 1507, indicating that only an insufficient reduction in resistance has been achieved.

Currently, in addition to MoSi2, W8i ze TaSi2 f
fi, TiSi2, etc. are being considered, and if a lower electrical resistance can be obtained with these high-melting point metal silicides than with conventional methods, it will be useful for applications in electrobalance and wiring of MIS field effect transistors, etc. Extremely useful.

Furthermore, the high melting point metal silicide film obtained by the above-mentioned thermal annealing method has poor uniformity and smoothness, and the strength of the film is 1. It has the disadvantage that it cannot be formed in a self-aligned manner with respect to interlayer insulating film patterns such as the above.

The purpose of the present invention is to solve the problem of high electrical resistance of high melting point metal silicide thin films obtained by conventional methods, improve the uniformity and smoothness of the film, and create a new high melting point film with excellent self-alignment. An object of the present invention is to provide a method for forming metal silicide.

(Means for solving the problem) According to the present invention, Mo, W, V, Nb, Ta
, Ti, Zr, and Hf 7) In the method of forming a high melting point metal silicide by reacting a high melting point metal consisting of z with silicon, when the high melting point metal film is deposited on a substrate having a silicon layer on at least the surface. In, Mo and W
for tetragonal fyjoSit and WSi, respectively.
2, hexagonal VSi z, NbSi x and Ta5 for V, Nb and Ta, respectively.
ix #For the temperature at which Ti, Zr and Hf are formed, the orthorhombic system Tf8i! , When performing vapor deposition of the high melting point metal while heating the substrate with the silicon layer to a temperature at which ZrSi* and Hf8i* are formed, the vapor deposition Ionize 10% or more of the particles, accelerate the ionized deposition particles by Q, IKeV or more, and then continue the deposition without ionization until the desired film thickness is reached, causing a silicidation reaction at the same time as the deposition. A method for forming a high melting point metal silicide is obtained.

(Function) In order to reduce the electrical resistance of high-melting point metal silicide, it is essential to promote the growth of crystal grains of a low-resistance crystal phase and to reduce stress such as stress acting on the grown crystal grains.

In the present invention, the substrate is heated to a temperature that allows a low-resistance crystalline phase of high-melting-point metal silicide to be vapor-deposited. can be obtained, and the stress acting on the crystal grains can be extremely reduced.

Furthermore, the reason why the smoothness, uniformity, and self-alignment of the high melting point metal silicide film deteriorates due to thermal reaction is that the reaction between the high melting point metal and silicon begins non-uniformly.

In the present invention, 10% or more of the high melting point metal particles equivalent to a film thickness of several tens of amps that reach the silicon substrate in the early stage of the reaction are 0.
The accelerated ions collide with the surface of the silicon substrate, uniformly mixing the surface layer of the silicon substrate, and uniformly starting a reaction within the surface of the silicon substrate.

As described above, according to the present invention, a uniform, low-resistance, high-melting point metal silicide film can be formed in a self-aligned manner with respect to a pattern of an insulating film such as SiOf.

(Example) FIG. 1 (fan, fb) is a schematic cross-sectional view showing the process of forming MoSi 24 on a P-type silicon substrate 1 according to the present invention. After normal acid cleaning, a P-type silicon substrate 1 having a 5iO-insulating M2 (400A) pattern with a clean surface treated with diluted hydrofluoric acid was heated to the lower limit of the tetragonal Mo8iz formation temperature in an ionization vapor deposition apparatus. The P-type silicon substrate is heated to 900° C. and the ionization rate is 20%, and the accelerating voltage is 1.
After ionizing Mo3 with a thickness of 40 people at 5 KV, Mo3 with a thickness of 360 A was further deposited without ionization, as shown in Figure 1(b). Uniform resistivity 60 μΩ・My MoSi* film 4
(approximately 100 OA) was formed only on the exposed Si surface in a self-aligned manner.

On the other hand, by conventional thermal annealing method, 40OA M
o When the metal film 3 is deposited on a substrate at room temperature and then annealed at 900°C for 20 minutes in a nitrogen atmosphere using an electric furnace, it becomes non-uniform and has a specific resistance of 150 μΩ as shown in Figure 2.
My Mo8iz film 4 was formed protruding over the Si0g insulating film 2.

With respect to other high melting point metal silicides, a smooth and uniform high melting point metal silicide film with lower resistance than the conventional method could be formed using the method of the present invention. In addition, in the above example, P
Although a type silicon substrate is used, an N type silicon substrate may also be used.

(Effects of the Invention) According to the present invention, a uniform, low-resistance, high-melting point metal silicide film can be self-aligned to the pattern of a 1D insulating film of 5 ioZ or the like by m'R:r.

[Brief explanation of drawings]

Figures 1(a) and (1)) show that M
FIG. 3 is a schematic cross-sectional view showing a process of forming an OS 12 film. Figure 2 shows MoS obtained by conventional thermal annealing method.
FIG. 2 is a schematic cross-sectional view of an i2 film. Fig. 1 (α) (b) Fig. 2 Mo 5i02 Kienmei oSi2 P-type silicon base

Claims (1)

[Claims] In a method of forming a high melting point metal silicide by reacting a high melting point metal silicon consisting of Mo, W, V, Nb, Ta, Ti, Zr and Hf, the high melting point metal is added to a substrate having a silicon layer on at least the surface thereof. When depositing films, tetragonal MoSi_2 is used for Mo and W, respectively.
and the temperature at which hexagonal system VSi_2NbSi_2 and TaSi_2 are formed for V, Nb and Ta, respectively, and the orthorhombic system TiSi_2, ZrSi_2 for Ti, Zr and Hf, respectively.
When the high melting point metal is vapor-deposited while the substrate with the silicon layer is heated to a temperature at which HfSi_2 is formed, 10% of the vapor-deposited particles are The method is characterized by ionizing the above particles, accelerating the ionized deposition particles by 0.1 KeV or more to deposit them, and then continuing the deposition in a non-ionized state until the desired film thickness is reached, causing a silicidation reaction to occur at the same time as the deposition. Method of forming high melting point metal silicide.