JPS5950214B2 - Manufacturing method of semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device, particularly a method of manufacturing wiring and electrodes, and improves the adhesion between an insulating film formed on a semiconductor substrate and a metal film for wiring and electrodes. Furthermore, an alloy layer of the electrode metal film and the semiconductor constituting the substrate can be easily formed in the contact area, and even after heat treatment at high temperatures close to 1000 degrees Celsius, it has good ohmic properties that prevent the electrode metal from coming off in shallow junctions. The aim is to get contacts who show

The following methods are considered necessary to reduce the wiring area and element dimensions and increase the speed of operation in ICs and LSIs.

(1) Use multilayer aluminum wiring.

(2) A high melting point material such as Mo is used for the gate electrode, the gate electrode is extended to form a wiring, and a direct contact is formed to the Si substrate.

(3) The junction depth of the diffusion layer provided on the semiconductor substrate is made shallow, about 0.1 to 0.8 μm.

In (1), in order to form an ohmic contact, 50
Heat treatment (jitter) at around 0℃ is performed multiple times, (2
), heat treatment at close to 1000°C is performed after electrodes and wiring are formed.

Even after such a long or high temperature heat treatment process (3
), it is desirable that the electrode metal maintain good ohmic properties with low contact resistance and no penetration into the junction. Various methods have been considered to meet the above requirements, as exemplified below.

In the jitter of conventional Al electrodes, Al destroys the junction because the atoms (silicon) that make up the semiconductor substrate dissolve in the Al film at high temperatures during jitter, and conversely, Al atoms form a diffusion layer in the substrate. In order to prevent this phenomenon, an A1 1-1% Si alloy film is used.

By including a large amount of Si in the Al film, junction breakdown can be eliminated, but from a practical standpoint, there are new problems such as Si precipitation due to heat treatment, deterioration of reliability against electromigration, and increase in contact resistance. problems occur. Therefore, since the actual Si concentration needs to be suppressed to about 0.5% to 1%, there is still a possibility of junction leakage for extremely shallow junctions. The A1 film and the semiconductor substrate (
An electrode structure (Si) with a polycrystalline Si film interposed between
There is A1 (polycrystalline Si-Si).

In this electrode, Al and polycrystalline Si are separated by heat treatment.
Since the Si layer reacts preferentially with the Si substrate, the Si substrate is not affected much, and the bond can be almost prevented from being destroyed. However, in order to lower the contact resistance of this electrode, it is necessary to diffuse into the polycrystalline Si layer a high concentration of impurity that has the same conductivity type as the diffusion layer, or, if no impurity is introduced, to reduce the thickness of the polycrystalline Si layer. must be 300 Å or less. That is, since A1 and the substrate Si do not come into direct contact with each other, there is a drawback that it is difficult to sufficiently lower the contact resistance when the contact window size is minute. T can be used as an electrode with low contact resistance and can form shallow junctions.
There is a method using i or Pt.

This person. In order to make an ohmic contact, when heat treatment is applied after Ti or Pt is deposited on the contact part of the Si substrate, the thin layer including the deposited metal-Si interface uniformly forms TiSi2 and PtSi due to a reaction. Become. Since the thickness of this metal silicide layer can be controlled by the heat treatment temperature and 3 hours, it has the feature that electrodes can be formed relatively easily even in shallow junction regions. However, Ti. Pt is an expensive material, and its adhesion to insulators such as SiO2 is A
Since the metal or metal silicide must be left only in the electrode portion, it is difficult to use it as a wiring material. In addition, other electrode forming methods have been proposed as follows.

That is, a thin Al or Sb layer of about 500 to 600 layers is provided in contact with a semiconductor substrate, inert gas atoms are injected into the surface of the metal layer, and the Al or Sb constituting the metal layer is removed by the knock-on effect. It is introduced onto the surface of the substrate to form a contact. In this way, when the substrate is Si, the introduced A1 becomes an acceptor and forms a P-type layer on the substrate surface, and Sb becomes a donor and forms an N-type layer on the surface of the substrate.
An ohmic contact can be obtained at the same time by forming a shallow junction depth of 1 μm or less. Using this method, the emitter, collector, base, and CMOS of bipolar semiconductor devices can be
When simultaneously creating electrodes for the source and drain of P-channel and N-channel transistors in a semiconductor device,
Different metals must be deposited on the contact portions that are to become the N-type layer and the P-type layer, which complicates the process. In addition, since the metal film is several hundred thin, in order to apply it to an actual semiconductor device, it is normal to further evaporate about 1 μm of A1, which will become the final electrode/wiring, on the thin metal layer. Additional heat treatment is required to recover from radiation damage during evaporation and to lower the contact resistance between the thin metal layer and A1.
A new problem with Al.L film sticking to shallow junctions is that Al. This is because a low melting point metal such as Sb does not act as a diffusion barrier for Al. Furthermore, high melting point transition metals MO, W and high melting point transition metal silicides MOSi2, WSi2, etc., which are useful as gate wiring of MOS type semiconductor devices, are inexpensive materials and can be used as wiring materials by extending the gate electrode. Although it has the advantage of being able to be heat-treated at a high temperature close to °C, the adhesion with the insulating film is still not strong, and even if the electrode is simply formed by CVD or sputtering and then heat-treated, it will not work on the Si substrate. There is a problem in that the contact resistance hardly reacts with the highly concentrated diffusion layer provided in the substrate, and as the heat treatment temperature increases, the contact resistance increases rapidly. The present invention eliminates the drawbacks of electrodes for shallow junctions as seen in the above conventional examples, has low contact resistance,
The present invention provides a new method for forming electrode wiring that has fewer leaders in shallow junctions even when heat-treated to temperatures close to 1000°C. The manufacturing method of the present invention will be explained below with reference to the drawings. 1 to 6 are cross-sectional views showing the formation process near the contact portion of a semiconductor device. The process in FIG. 1 forms a shallow diffusion layer 2 having a conductivity type opposite to that of the substrate 1 on a single silicon substrate 1. After that, SiO.

A stage is shown in which a film 3 is formed on the surfaces of layers 1 and 2, and a part of the film 3 above the diffusion layer 2 is selectively opened by photoetching to provide a contact window. Next, an MO film 4 made of a high melting point transition metal is deposited over the entire surface formed in the step of FIG. 1 to a thickness of approximately 500 mm by sputtering, electron beam evaporation, etc. (FIG. 2). Furthermore, through the MO film 4, inert gas ions such as Ar or impurity ions having the same conductivity type as the diffusion layer 2, that is, impurities of the opposite conductivity type to the substrate, are implanted into the MO film 4.
It is introduced into a layer below the film 4, particularly in a region including the interface between the film 4 and the diffusion layer 2. At this time, the ions incident from the surface of the MO film 4 collide with MO atoms, and the MO atoms receive the energy.
Atoms proceed while generating lattice defects in the diffusion layer 2 due to the knock-on effect, stop very close to the surface of the diffusion layer 2, and are introduced into the diffusion layer 2, so that a large number of atoms are generated near the interface between MO4 and the diffusion layer 2. A MO-Si alloy layer 5 containing lattice defects is formed.

The specific conditions are: MO4 film thickness is 500Λ, implanted ions are Ar, implantation energy is approximately 100 KeV, DOs
If the amount of e is 1015~5×1015/Cm2, Ar
The concentration peak of is located near the interface between MO4 and the diffusion layer 2,
The thickness of the MO-Si alloy layer 5 can be approximately 300Λ.

Therefore, the depth of the alloy layer 5 can be kept sufficiently smaller than the bonding depth. Furthermore, MO atoms are introduced not only into the MO-Si contact surface but also into the very thin surface layer of the SiO2 film 3 due to the knock-on effect, forming an MO-SiO transition layer. It is possible to strengthen the adhesion with the membrane 3 (Fig. 3). Thereafter, an MO film 6 is further deposited to a thickness of about 1 ftm (FIG. 4), and then photoetching is performed to selectively remove the films 4 and 6 to form a wiring pattern (FIG. 5).

Note that the metal film 6 is made of a metal other than MO, for example, ALAl/Si.
etc. may be used. Layer 5 is a uniformly homogeneous layer containing many defects due to ion implantation, and is heated at 400°C to 6°C in order to anneal them and turn them into silicide of high melting point metal.
Heat treatment is performed at a temperature of about 00°C. As described above, in the electrode manufacturing method of the present invention, an alloy film of a high melting point transition metal such as MO or a semiconductor is used, and ions are implanted near the semiconductor interface, so an intermediate layer is created at the interface between the insulating film and the MO. Therefore, the adhesion of MO can be improved, and a uniform MO-semiconductor alloy layer can be stably formed at the contact interface with good reproducibility at room temperature.

Compared to alloy layers formed by conventional methods, this alloy layer is extremely effective in preventing interdiffusion between the metal atoms that make up the electrode and the semiconductor atoms of the substrate even after high-temperature heat treatment. Constantly low contact resistance (
It has a special property of maintaining a resistance of 10-゜Ω・Cm2).

Therefore, in the electrode structure shown in the embodiment of the present invention, 100
Even when heat treatment is performed at around 0° C., because the alloy layer is formed by ion implantation, the MO does not slip into the junction due to interdiffusion, and can withstand shallow junctions. Such properties are similar to other low melting point metals (ALSb
etc.), this cannot be expected.

Because of this property, it is necessary to increase the density of MOS type (including NMOS and CMOS) high-speed LSIs that have high-melting point metal gate wiring such as MO, and MO-Si direct contact that must withstand high-temperature heat treatment processes of about 1000 degrees Celsius. The present invention also exhibits its effects in contact formation. The manufacturing method of the present invention is a high melting point transition metal film other than MO or M
OSi. It can also be used when an alloy film of a high melting point transition metal and an element constituting a semiconductor is brought into contact with a semiconductor substrate. In particular, alloy films have almost the same acid resistance as semiconductor substrates, and have the advantage of facilitating various surface treatments in semiconductor processes compared to the case of using metals. Even if MO6 is replaced with Al or Al/Si, the high melting point metal-semiconductor alloy layer 5 acts as a sufficient Al diffusion barrier, so the heat treatment temperature can be increased.

Therefore, even for shallow junctions, electrodes can be easily formed without junction leakage being a problem. Moreover, unlike Al and Sb, high melting point transition metals such as MO do not become donors or acceptors even when introduced into a semiconductor substrate, and do not affect the conductivity type of the semiconductor substrate. Even when layers coexist, ohmic contacts with low contact resistance can be formed simultaneously to both layers through a simple process. Therefore, it is effective as a method for forming electrodes for shallow junctions in bipolar transistors and CMOS devices.

[Brief explanation of the drawing]

1 to 5 are cross-sectional views showing the manufacturing process of wiring and electrodes of a semiconductor integrated circuit device according to an embodiment of the present invention.゛1... Silicon substrate,
2... Diffusion layer having a conductivity type opposite to that of the silicon substrate 1, 3... SiO2 film, 4... Thin MO film, 5... MO-Si Alloy layer, 6...
...Thick MO film.

Claims (1)

[Claims] 1. After opening a part of an insulating film formed on the surface of a semiconductor substrate to expose the surface of the semiconductor substrate, a film of a high melting point transition metal or a film of this metal is formed to cover the opening. a step of depositing an alloy film with an element constituting the semiconductor; and a step of implanting ions from above the metal film or alloy film to introduce atoms constituting the metal film or alloy film into the substrate; or a step of forming an alloy layer of atoms constituting an alloy film and atoms constituting the semiconductor, and after the ion implantation, heat treating the alloy layer to establish contact between the semiconductor substrate and the metal film or the alloy film. A method for manufacturing a semiconductor device, comprising the steps of forming a metal film or an alloy film, and further forming a metal film on the metal film or alloy film. 2. Claim 1, which includes the step of implanting ions from above the metal film or alloy film so that the implanted ion concentration becomes approximately maximum in the vicinity of the interface between the metal film or alloy film and the semiconductor substrate. A method for manufacturing a semiconductor device according to . 3. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein the high melting point transition metal is a Mo film.