JPH0414219A - Formation of electrode wiring of semiconductor element - Google Patents

Abstract

PURPOSE:To make it possible to form an electrode wiring, which is high in heat resistance and has good contact characteristics to a shallow diffused layer, by a method wherein a contact hole is opened and thereafter, a high-melting point metal film is applied on the whole surface, an Si substrate is cooled and after a multilayer adsorption layer consisting of NH3 gas is formed thereon, a barrier metal layer consisting of a high-melting point nitride metal is formed. CONSTITUTION:A Ti film 14 which is used as a barrier metal layer is deposited and thereafter, an Si substrate 11 is dipped in liquid nitrogen or the like and is held at 0 deg.C or lower. NH3 gas is introduced in a reaction chamber and a multilayer adsorption layer 15 consisting of the NH3 gas is formed on the surface of the film 14. In the case of this layer 15, the feed amount of the NH3 gas, which consist of reaction molecules, to the film 14 is increased more than that in the case of a single layer adsorption layer. As a result, when an excitation reaction using ultraviolet light is used for a nitriding reaction, an absorption wavelength to the ultraviolet light is shifted to the side of a high wavelength and the absorption amount of the NH3 gas is increased. Accordingly, the nitriding reaction only of the film 14 is caused at a large reaction rate, a TiN layer 16 of a desired film thickness is formed and the improvement of the heat resistance of a semiconductor element is contrived.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to bipolar integrated circuits (IC, LSI, etc.) and MO8 integrated circuits (I) using a Si substrate (silicon substrate).
The present invention relates to a method for forming electrode wiring for semiconductor devices such as C, LSI, etc.).

(Prior Art) Conventionally, this type of LSI electrode wiring formation has been performed, for example, as shown in FIGS. 2(a) to 2(C). below,
Each manufacturing process (1) to (3) will be explained.

(1> Process shown in FIG. 2(a)) First, semiconductor elements such as source/drain diffusion layers are formed on the Si substrate 1, then an interlayer insulating film 2 is deposited on the entire surface, and contact holes 3 are formed in predetermined areas. Next, remove the Ti film (
Deposit titanium film) 4 by 500 people.

(2) Heating is performed at 800° C. for 10 seconds in a N2 gas (nitrogen gas) atmosphere using the process lamp annealing apparatus shown in FIG. 2(b).

As a result, a TiSi2 layer (silicon titanium layer) 5 is formed at the interface between the Ti film 4 and the Si substrate 1 in the contact hole 3.
is formed, and furthermore, a TiN layer (titanium nitride layer>4a) is simultaneously formed on the TiSi2 layer 5 and the interlayer insulating film 2. Next, A and Q containing 1% Si are formed on the entire surface.
- Deposit 1 μm of 8i layer 6.

(3) In the process shown in Fig. 2(c), A, f! The -3i layer 6 and the TiN layer 4a are selectively processed and processed into a wiring pattern having an Aρ-3i/TiN structure, that is, a wiring M7. Thereafter, a PSG film (phosphorus glass film>8a) and a SiN film (silicon nitride film>8b) for preventing moisture intrusion are deposited as the passivation film 8.

(Problem to be Solved by the Invention) However, in the above electrode wiring formation method, TiSi
The second layer 5 provides ohmic relationship with the diffusion layer (not shown) formed in the Si substrate 1, and the AN-8i in the wiring layer 7
The aim is to provide the TiN layer 4a with a barrier effect against the thermal reaction of the layer 6. On the other hand, in the reaction of Ti in the N2 gas atmosphere, the following two competing reactions occur simultaneously on the Si substrate 1.

Ti+28i-+TiSi2 ΔHf=-32, I Kca, I)/mo, [)...
・(1> Ti×N2→TiN ΔHf=-80,4KcaF/mofJ・・・・・・(
2) From the enthalpy ΔHf, the reaction of equation (2>) is easier to proceed. However, in the case of the solid phase reaction of equation (1), the concentration of the reactant is much higher, so in terms of reaction rate, equation (2) than(
1) Equation has a higher reaction rate. In the process shown in FIG. 2(b), in the case of lamp heating at 800° C. for 10 seconds, the thickness of the TiN layer 4a is approximately 100 people,
The i2 layer 5 is formed to a thickness of about 0.2 μm. If the TiSi2 layer 5 is thick and the diffusion layer (not shown) formed therein in the Si substrate 1 is shallow, junction leakage will occur due to Si consumption in the diffusion layer. On the other hand, if the TiN layer 4a is thin, the heat resistance is low, and junction leakage occurs due to the A1 spike of the A and Q-3i layers 6. Therefore, when semiconductor devices are made into ultra-LSIs, the TiSi2 layer 5 must be made as thin as possible and the TiN layer 4a must be made thicker, otherwise application to the ultra-LSI will become difficult.

However, in the process shown in FIG. 2(b), if the lamp heating temperature is made higher than 800°C, the equation (1) and (
2) The difference in reaction rate with the formula becomes larger, and TiN
The layer 4a becomes thinner, and the TiSi2 layer 5 becomes even thicker. Conversely, if the heating temperature is lowered, unreacted Ti remains on the interlayer insulating film 2, and the resistance of AfJ in the wiring layer 7 increases during subsequent heat treatment. Therefore, in order to increase the reaction rate of the above equation (2) and increase the thickness of the TiN layer 4a, it is conceivable to use NH3 gas (ammonia gas) instead of N2 gas as the heating atmosphere. Even if , the reaction rate of equation (1) proceeds more easily, so no great effect can be obtained.

As described above, if the T i S i 2 layer 5, which is an ohmic metal layer, is thick on the Si substrate 1, junction leakage will occur due to consumption of the Si substrate 1 (approximately 2.4 times the thickness of the Ti film). Or, the TiN layer 4a, which is a barrier metal layer, becomes thinner in inverse proportion to the thickness of the TiSi2 layer 5, and the wiring N
The barrier effect against A and Q in 7 is reduced and junction leakage occurs. In order to solve this problem, it may be possible to use a method in which a complete TiN layer 4a is not formed by low-temperature nitridation in the process shown in FIG. The resistance value of A and 11 increases due to the reaction of the wiring layer 7 with unreacted Ti. Therefore, no matter which method was adopted, a technically satisfactory product could not be obtained.

The present invention addresses the problems that the prior art had, in that it is difficult to make the TiN layer, which is a barrier metal layer, thick and the TiSi2 layer, which is an ohmic metal layer, as thin as possible, resulting in low heat resistance and shallow diffusion. The present invention provides a method for forming electrode wiring of a semiconductor device that solves the problem of deterioration of contact characteristics for layers.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the first invention provides a method for forming electrode wiring of a semiconductor element constituted by an LSI or the like, in which an interlayer insulating film is formed on a Si substrate on which an element is formed. After depositing and forming contact holes in predetermined areas, a first step of depositing a high melting point metal film on the entire surface, cooling the Si substrate, and forming a multilayer adsorption layer of NH3 gas on the high melting point metal film. a second step of forming a barrier metal layer made of a high melting point metal nitride to a predetermined thickness by irradiating ultraviolet light of a predetermined wavelength from above the multilayer adsorption layer in NH3 gas; The Si substrate is heated to a predetermined temperature and heated with N2 gas or NH3 gas to bond the high melting point metal film and the S in the contact hole.
a third step of reacting with the i-substrate to form an ohmic metal layer in the Si substrate; and a fourth step of selectively forming a wiring layer on the contact hole and forming a passivation film thereon. These steps are performed in order.

In a second invention, in the first invention, in the second step, the Si substrate is cooled to 0° C. or less, and ultraviolet light with a wavelength of 210 nm or less is irradiated from above the multilayer adsorption layer perpendicularly to the Si substrate. In the third step, the Si substrate is
It is heated to 75-900°C.

(Function) According to the first invention, since the method for forming electrode wiring of a semiconductor element is configured as described above, in the second step, by using N H3 scum as a reaction gas and cooling the Si substrate, A multilayer adsorption layer of NH3 gas without forming is formed by a high melting point metal film (e.g., titanium, Ti, etc.) of reactive molecules (NH3).
tungsten W, zirconium Zr, etc.)
It has the function of increasing the amount of adsorption compared to a single layer adsorption layer.

When irradiating ultraviolet light from above this multilayer adsorption layer to form a barrier metal layer made of a nitrided high-melting point metal (e.g., TiN, WN, ZrN, etc.), an excitation reaction by ultraviolet light is used for the nitriding reaction. The absorption wavelength for ultraviolet light (for example, 210 nm) is shifted to the higher wavelength side compared to that in the gas phase,
The amount of absorption of NH3 to ultraviolet light increases.

Due to the effects of such a multilayer adsorption layer and ultraviolet light irradiation, the growth rate of the high melting point metal nitride becomes larger than before, even at low temperatures (for example, below 0° C.), due to the reaction of the following equation (3).

2 T i + 2 N H3 → 2 T iN + 3
H2...(3) During the reaction of formula (3), the silicide reaction does not occur due to the low temperature. After the high melting point metal film is converted into a barrier metal layer made of a high melting point metal nitride having a desired thickness by a photoexcitation reaction, the process proceeds to the third step.

In the third step, the remaining unreacted high melting point metal film is coated with an ohmic metal layer (for example, T i S i 2 = WS
i2, ZrSi2, etc.) formation critical temperature (e.g. 70
By heating at a temperature of about 0° C.), an ohmic metal layer with a desired thickness is formed, and the photoexcitation barrier metal layer formed in the second step is made more dense.

In this manner, in the second step, only the nitriding reaction of the high melting point metal film occurs at a higher reaction rate than in the past, and a barrier metal layer with a desired thickness is formed.

Thereafter, in a third step, an ohmic metal layer having a desired thickness is independently formed by a solid phase reaction between the remaining unreacted high melting point metal film and the Si substrate.

According to the second invention, in the second step, cooling the Si substrate to 0° C. or lower and irradiating ultraviolet light with a wavelength of 210 nm or lower from above the multilayer adsorption layer can be performed even at a low temperature of 0° C. or lower. Due to the reaction in formula 3), the growth route of the barrier metal layer becomes larger than before. Moreover, in the third step,
Heating the Si substrate to 675-900°C allows easy control of the thickness of the ohmic metal layer and
The photo-excited barrier metal layer formed in the process can be made more dense.

Therefore, the above problem can be solved.

(Example) FIGS. 1(a) to 1(d) are manufacturing process diagrams for explaining a method for forming electrode wiring of a semiconductor device according to an example of the present invention. Steps (1) to (4)
Explain.

(1) Process of FIG. 1(a) After introducing impurities to form a diffusion layer on the Si substrate 11, an interlayer insulating film 12 such as a PSG film is formed by vapor phase growth (CVD).
method) etc. A contact hole 13 is formed in a predetermined region of the interlayer insulating film 12 by photolithography technology. Then, a high melting point metal film, for example, a Ti film 14, which will become a barrier metal layer, is deposited by magnetron sputtering or the like.

Next, the Si substrate 11 is immersed in liquid nitrogen or the like, and the Si substrate 11 is maintained at 0°C or lower, for example, about -80°C.

Then, NH3 gas is introduced into the reaction chamber, and the NH3 gas forms a multilayer adsorption layer 15 of NH3 gas on the surface of the Ti film 14. Thereafter, in NH3 gas, ultraviolet light H having a wavelength of 210 nm or less is irradiated perpendicularly to the Si substrate 11 using a low-pressure mercury lamp or the like.

(2) Step of FIG. 1(b) In the ultraviolet light irradiation step, the ultraviolet light absorption wavelength of NH3 gas is 200 to 210 nm in the gas phase, but in the case of the multilayer adsorption layer 15, it shifts to the higher wavelength side. It is known. On the other hand, when a low-pressure mercury lamp, for example, is used for ultraviolet light irradiation, the wavelength of the resonance line of the low-pressure mercury lamp is 1
Since the wavelengths are 85 nm and 254 nm, NH3 gas sufficiently absorbs and excites ultraviolet light. This photoexcitation reaction causes 8
Even at a low temperature of 0° C., the nitridation reaction proceeds from the surface of the Ti film 14 according to equation (3) above, and the TiN layer 16, which is a barrier metal layer, grows at a growth rate of, for example, 45° C.
It is formed to a thickness of about 0.8 mm. During this nitriding reaction, no silicide reaction occurs due to the low temperature.

(3) Step in FIG. 1(c) Stop cooling the Si substrate 11, and use a halogen lamp etc.
The Si substrate 11 is heated for about 10 seconds at a critical temperature for T1S12 formation of 675 to 900°C, for example 800°C, and the whole is heated with N2 gas or NH3 gas. Then, according to the above formula (1), unreacted Ti with a thickness of, for example, about 500 mm is formed.
The film 14 and the Si substrate 11 undergo a solid phase reaction, and the contact hole 1
3, only below the ohmic metal layer with a thickness of 100 mm.
About eight T1S12 layers 17 are formed. At this time, the thickness of the TiN layer 16 above the contact hole 13 hardly increases, but the TiN layer 16 becomes more dense. Since no silicidation reaction occurs on the interlayer insulating film 12,
Unreacted T of 50 people in the process of FIG. 1(b)
The i film 14 changes into a TiN layer 16.

(4) In the process example shown in FIG. 1(d), an Aρ-3i layer 18 containing 1% Si is deposited to a thickness of about 1 μm. Then, by photolithography technology and reactive ion etching, the A1-8i layer 18 and the Ti
The N layer 16 is processed into a predetermined wiring pattern, and one wiring layer is formed over the contact hole 13. After that, the PSG film 20a and 5iNJlli20 are used as the passivation film 20.
By depositing the layer b by plasma CVD or the like, the process of forming the electrode wiring is completed.

This embodiment has the following advantages.

In the process of Figure 1 (a>, (b)), S
The i-substrate 11 is cooled to form a multilayer adsorption layer 15 of NH3 scum. This multilayer adsorption layer 15 is composed of NH3 which is a reactive molecule.
The amount of gas supplied to Tiii is larger than that of a single layer adsorption layer. Therefore, when an excitation reaction using ultraviolet light is used for the nitriding reaction, the absorption wavelength for the ultraviolet light shifts to the higher wavelength side and the amount of absorption of NH3 gas for the ultraviolet light increases. Irradiate the light H. Then, only the nitriding reaction of Tiii occurs at a higher reaction rate than before, and a TiN layer 16 with a desired thickness is formed. In this way, since the TiN layer 16 to be thickened is first formed to a desired thickness, heat resistance can be improved.

Next, the thickness of the TiSi2 layer 17 to be made thinner is determined by the thickness of the remaining unreacted Ti layer 14, so
By controlling the film thickness of ii and the film thickness of the TiN layer 16, the film thickness of the T i S i 2 layer 17 can also be controlled. Therefore, the critical temperature for TiSi2 formation is 675-900℃,
For example, by lamp heating at about 800°C, the remaining unreacted Ti
By an in-phase reaction between the film 14 and the Si substrate 11 according to the above equation (1), a TiSi2 layer 17 of a desired thickness is independently formed.

In this way, since the nitriding reaction and the silicidation reaction occur independently, the electrode wiring forming method of this embodiment can be applied to semiconductor devices having shallow diffusion layers or semiconductor devices that require a lot of heat treatment such as multilayer wiring. It becomes possible to form electrode wiring with good contact characteristics.

Note that the present invention is not limited to the above embodiments, and various modifications are possible. Examples of such modifications include the following.

(i) In the above embodiment, Tiii is used as the high melting point metal film.
Although I was used, other high melting point metal films such as W and Zr may also be used.

(++) Although the barrier metal layer made of a high melting point metal nitride is formed of the TiN layer 16, it may be formed of other high melting point metal nitride such as WN or ZrN.

(iii > In the process of Figure 1 (a), the Si substrate 11 was cooled to -80°C, but if this cooling temperature is within the range of 0°C or lower to liquid nitrogen temperature, cooling other than -80°C is possible. It may also be temperature.

(iv) In the step of FIG. 1(c), the Si substrate 1
1 was heated to about 800° C., but depending on the critical temperature for forming the nitrided high-melting point metal film, heating may be performed at a temperature in the range of 675 to 900° C., or at a temperature other than that.

(V> Although the ohmic metal layer is formed of the TiSi2 layer 17, it may be formed of other metal layers such as WSi2 and ZrSi2.

(Effects of the Invention) As explained in detail above, according to the first and second inventions, the barrier metal layer is made thicker or the barrier metal layer is formed to a desired thickness first, so that heat resistance can be improved. can be achieved. Next, the thickness of the ohmic metal layer to be made thinner is determined by the thickness of the remaining unreacted high melting point metal film, so the thickness of the initial high melting point metal film and the thickness of the barrier metal layer made of the high melting point metal nitride are controlled. This allows the thickness of the ohmic metal layer to be controlled to a desired thickness. In this way, since the nitridation reaction and the silicidation reaction occur independently, it is possible to accurately form an electrode wiring having high heat resistance and good contact characteristics even to a shallow diffusion layer.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1(a) to (d) are manufacturing process diagrams for explaining a method for forming electrode wiring of a semiconductor device according to an embodiment of the present invention, and FIGS. 2(a) to (C) ) is a manufacturing process diagram for explaining a conventional method for forming electrode wiring of a semiconductor element. 11... Si substrate, 12... Interlayer insulating film, 13... Contact hole, 14...
Ti film, 15...Multilayer adsorption layer, 16...
・TiN layer, 17...TiSi2 layer, 18...
...A, ll-3i layer, 19... wiring layer,
20... Passivation film, H...
ultraviolet light.

Claims (1)

[Claims] 1. A first step of depositing an interlayer insulating film on the Si substrate on which the device is formed, forming contact holes in predetermined areas, and then coating the entire surface with a high melting point metal film. After cooling the Si substrate and forming a multilayer adsorption layer of NH_3 gas on the high melting point metal film, ultraviolet light of a predetermined wavelength is irradiated from above the multilayer adsorption layer in NH_3 gas to remove the nitrided high melting point metal. a second step of forming a barrier metal layer with a predetermined thickness; and heating the Si substrate to a predetermined temperature and injecting it with N_2 gas or N_2 gas or N_2 gas.
a third step of heating with H_3 gas to cause the high melting point metal film in the contact hole to react with the Si substrate to form an ohmic metal layer in the Si substrate; and selecting a wiring layer on the contact hole. A method for forming an electrode wiring of a semiconductor device, characterized in that a fourth step of forming a passivation film thereon is sequentially performed. 2. The method for forming electrode wiring of a semiconductor device according to claim 1, wherein in the second step, the Si substrate is cooled to 0° C. or less, and ultraviolet light with a wavelength of 210 nm or less is applied to the Si substrate from above the multilayer adsorption layer. A method for forming an electrode wiring of a semiconductor device, characterized in that the Si substrate is heated to 675 to 900° C. in the third step.