Method for manufacturing semiconductor device

FIELD: electronic engineering; integrated circuit manufacture on silicon.

SUBSTANCE: proposed method includes formation of active areas of devices on substrate; masking; opening of contact cuts for active areas; formation of metal deposition system that has amorphous metallide possessing negative mixing heat and incorporating components characterized in higher pressure of inherent vapors or higher sublimation heat than substrate material, and other components of metal deposition system. High stability of metal deposition system provides for manufacturing semiconductor device capable of operating at high temperatures approximately over 650 °C.

EFFECT: provision for preventing ingress of metal deposition system components into active area and escape of impurities from the latter.

6 cl, 2 dwg, 1 tbl

 

The scope of the invention is the electronic equipment, and more specifically the technology of production of integrated circuits (ICS) on silicon. The invention can be used for the manufacture of a metallization system of intellectual property.

Known semiconductor device with a metallization system containing alloy of Al-si(5%), titanium nitride TiN, titanium disilicide TiSi2[1]. The disadvantage of it is that it is only stable up to a temperature of 500° C. moreover, as follows from the experimental results, already at this temperature was found penetration of copper on the border of the active region of the device, that is unacceptable.

There are also other systems metallization for semiconductor devices, which contain copper si and diboride TiB2[2] or tantalum nitride TaN [3]. The disadvantage of these systems is that the limit of their stability is the temperature 600-680° that is only 60-65% of the melting temperature of copper. In addition, TiB2and TaN have sufficiently high resistivity 450-500 µohm· cm and reduce the total resistance of the metallization system.

Also known in the metallization system, which contains material on the basis of a carbide of a metal selected from the group of tungsten, molybdenum, tantalum, titanium, niobium, zirconium, vanadium and chromium, which create thermodynamicist the stable couple with silicon and its compounds at temperatures above about 500° C. In the metallization system of IP, along with silicon, includes materials based on aluminum or copper, which may contain impurities. From the literature [1-3] it is well known that a very common cause degradation of electrical characteristics of a semiconductor device penetration is exactly the atoms of copper, aluminum or impurities from the system metallization on the border and into the active area of the device. The disadvantage of this method [4] is that it uses the materials selected only from the point of view of stability in a pair of silicon, and does not take into account the presence of other elements. As a result, it affects the temperature stability is only over 500° With, while some possible subsequent processes can be carried out at temperatures above 600-650° C.

The closest technical solution of the present invention is a method comprising the following process steps [5]. Forming on the substrate active areas of the devices, masking, opening contact Windows to the active regions, forming the metallization system containing amorphous metallic selected from the group consisting of a transition metal, a transition metal/normal metal alloy and a transition metal/metalloid alloy, the above-mentioned layer is amorphous when standing.

The disadvantage of this method [5] is that it uses materials Ni-Mo, Ni-Nb, Mo-Si, W-Si and Ni-Ta though they are amorphous and have a crystallization temperature of 800-900° but in contact, in particular with a layer of aluminum crystallize and interact with them already when 525-530° From [6].

The purpose of this invention is to provide a semiconductor device capable of withstanding the high temperature manufacturing operations at temperatures above about 650° through the use of a stable system metallization, which prevents the penetration of various components in the active region, and impurities of the active region.

To achieve the technical result in the method of manufacturing a semiconductor device, comprising forming on a silicon substrate in the active regions of the devices, masking, opening contact Windows to the active regions, forming the metallization system, which uses amorphous metallic, which has a negative heat of mixing (Ecm), the components of which have a lower pressure of vaporized or higher heat of sublimation than the substrate material and other components of the materials of the metallization system.

Thus, the distinctive features of the invention is that the system metallization with the holding amorphous metallic, having a negative heat of mixing, the components of which have a lower pressure of vaporized or higher heat of sublimation than the substrate material and other components of the materials of the metallization system.

This set of distinctive features eliminates the disadvantages of the method [5] and to obtain a semiconductor device capable of withstanding the high temperature manufacturing operations at temperatures above about 650° through the use of a stable system metallization, which prevents the penetration of various components in the active region and impurities from the active region.

In modern microelectronics is the most widely used system metallization containing material based on copper or aluminum. When applying high temperature operations necessary to ensure the safety of the predetermined settings of the device, which in turn requires the creation of a highly stable system metallization, which prevents such degradation phenomenon as a change in electrical parameters of the devices until their failure due to penetration of the individual components of the system metallization, such as aluminum and copper, on the border of the metallization with the active regions of the semiconductor.

Common cause degradation of the device is chemicas the first interaction between the metallization and the substrate, in particular silicon, either within the metallization system, in which other substances are formed. The desire to mixing and interaction is characterized by the energy (heat) mixing. First of all, a positive value of the energy of mixing is characterized by the aspiration system components to mix, and at Ecm2· k· T (Ecm- mixing energy, k is Boltzmann's constant, T is the temperature) is observed splitting. The negative value of the energy of mixing indicates a tendency towards unification. If the material is characterized by a negative mixing energy, the interaction of this material with other components of the system metallization is less likely than a material with a positive mixing energy. Moreover, the negative mixing energy, the lower the probability of its interaction.

The process of interaction primarily occurs at the interface of the phase boundary, as there is a local increase in free energy. Therefore, to reduce the velocity of degradation of all the main components of the material, preventing degradation, should have low surface activity, or, in other words, you have no energy benefit out of the atoms of the material of the volume. Parameter for evaluation of surface the activity of the components may be a comparison of the heats of sublimation of components or pressure of its own vapor above the surface: the heat of sublimation of the above and the pressure of vaporized below the lower surface activity of the component.

Another way of degradation of the device is the diffusion of atoms from one material to another. It is now known that the diffusion along the phase boundaries and grain boundaries in polycrystalline materials has the lowest activation energy and runs ten times faster than the bulk lattice diffusion. In this regard, it is the emergence of diffusion at the grain boundaries is the cause of low-temperature degradation of the metallization system, which uses polycrystalline material. To avoid it is advisable to use an amorphous material in which grain boundaries are absent.

In accordance with the above as components of Metallica in the composition of the metallization system can be selected from elements from group W, TA, Nb, Mo. First, as can be seen in table 1, are elements that have one of the biggest values of the heat of sublimation and one of the lowest values of the pressure of its own vapor and, therefore, are not surface-active, among other system components metallization and therefore do not tend to accumulate at the phase boundaries. Secondly, the system W-Ta and W-Nb, Ta, Mo, Nb-Mo represent a continuous series of solid solutions [7], and, consequently, the magnitude is the power of mixing of these systems is negative [8]. Thirdly, the thin film alloys W-Ta and W-Nb, Ta, Mo, Nb-Mo, besieged, in particular, by ion-plasma sputtering, are amorphous.

Table 1

Heat sublimation Δ NS298and the decimal logarithm of the pressure of its own vapour above the surface of the lgP298at 298 K [6]
System components metallizationΔ NS298, kcallgP298
Si108,0-49,4
Al78,7-44,2
C80,68-48,7
Ti112,6-74,2
Co102,38 
Ni102.49 euros-47,4
Components MetallicaΔ NS298, kcallgP298
Nb172,5 
Moto 158.4-85,5
The186,5-113,0
W203,5-142,7

As amorphous Metallica it is advisable to use material W-Ta, because the energy of mixing is negative, and its components have the highest heats of Sublim the tion and the lowest pressure of its own vapor [6].

In order to increase the temperature range of existence of a stable system metallization, slowing down the process of degradation and increase the stability of the amorphous state of Metallica need to make a dopant from the group of nitrogen, carbon, boron, silicon, phosphorus, germanium, arsenic. These dopant, on the one hand, improves the stability of the amorphous state Metallica [9], and on the other, egregious in areas with high free energy, such as the phase boundary, grain boundary, the local inhomogeneity and others, and Passepartout them, thus preventing the degradation process.

The drawing shows the stages of the proposed method of creating a semiconductor device.

In the drawing, and the substrate 1 formed with the active regions 2, a masking dielectric 3 and the contact Windows 4, 5.

In the drawing, b shows the structure formed by the metallization system 6, which contains a layer of amorphous Metallica and other planes, including interlevel dielectric.

This method can be used, for example, to create a bipolar transistor active regions in the n-epitaxial layer and the contact Windows through the dielectric layer, for example silicon dioxide SiO2. The composition of the metallization providing interconnect active about the t through the contact window, includes titanium silicide, providing the necessary electrical contact with the active region to the silicon, to ensure the stability of the device during high-temperature operations, amorphous metallic Ta-W containing nitrogen as an alloying agent, and an alloy of Al-si(5%), providing a low resistance. The components of this Metallica TA and W have the lowest pressure of vaporized or the high heat of sublimation than the other components of the materials of the metallization system. Nitrogen as a dopant segregates in areas with high free energy, increases the stability of the amorphous state of Metallica Ta-W and reduces the tendency to degradation of the metallization system even during high-temperature treatments above about 65° C. the Etching pattern of the metallization system should be performed in a chlorinated plasma. On top of the metallization system is formed planarize dielectric, for example silicon dioxide SiO2.

Accordingly, the invention is applicable in the manufacture of integrated circuits and is quite technical. Can be used for the manufacture of such devices, as well as when using a prototype of the invention, but with a more stable system interconnects.

The source of information

1. Lu JP, W.Y. Hsu, etc. "Thermalstability of Al/barrier/TiSi xmultilayer structures". Thin Solid Films 32-p.2-25, 1998

2. Sade G., J. Pelleg "Co-sputtered TiB2as diffusion barrier for advanced microelectronic with Cu metallization". Applied Surface Science 91, SCR-268, 1995

3. Wen flood Yang, Wen-Fa Wu and other "Barrier capability of TaNxfilms deposited by different nitrogen flow rate against Cu diffusion in Cu/TaNx/n+-p junction diodes. Solid-State Electronics 45, str-159, 2-1,

4. U.S. patent N 54143-1.

5. U.S. patent N 4494136 prototype.

6. Veretin UD, Mashiri VP, N. Ryabtsev, V.I. Tarasov, Rogozkin D., I. Korobov Thermodynamic properties of inorganic substances // Directory. Edited Appepeave. M: Atomizdat, 1965, -46-C.

7. Hansen M. Patterns of double alloys. Reference: t/Mhansen, Kandenko.-M., 1962. -1488 C.

8. Chistyakov UD, Rinova P. Physico-chemical fundamentals of microelectronics technology//M.: metallurgy, 1979. 4-9 C.

9. Physical encyclopedic dictionary. Edited Amerkhanov //M: “Soviet encyclopedia”, 1984. -944 S. (p.4-8).

10. A.R. Miedema, Boom R., De Boer F.R. On the heat of formation of solid alloys // J. Less-Common Metals, 1975, p.283-298.

1. A method of manufacturing a semiconductor device, comprising forming on a substrate active areas of the devices, masking, opening contact Windows to the active regions, forming the metallization system containing amorphous metallic, characterized in that the specified metallic has a negative heat of mixing, and the components of which have a lower pressure is vaporized or higher heat of sublimation, than the substrate material and other components of the metallization system.

2. The method according to claim 1, characterized in that the components specified Metallica are selected from the group of W, Ta, Nb, Mo.

3. The method according to claim 2, characterized in that the components specified amorphous Metallica are W and TA.

4. The method according to claim 1, characterized in that the amorphous metallic includes a dopant of a range of nitrogen, carbon, boron, silicon, phosphorus, germanium, arsenic, antimony.

5. The method according to PP and 4, characterized in that the amorphous metallic, components of which are W and That includes nitrogen as alloying impurity.

6. The method according to claims 4 and 5, characterized in that the amorphous metallic, components of which are W and TA containing nitrogen as alloying impurity includes silicon as alloying impurity.



 

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