JPS59100565A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the deposition of Si on wiring parts and to prevent the deposition of Si into a block layer, by arranging the block layer comprising TiN in the vicinity of the bottom part of the wiring comprising an Al-Cu or Al-Mg layer. CONSTITUTION:A wiring part is formed by the lamination of the following layers in the order of description from the bottom: an Al or an Al alloy layer 16 having a thickness of about 500-1,500Angstrom ; a TiN layer 17 having a thickness of 500-1,500Angstrom ; and an Al-Cu or Al-Mg layer 18 having a thickness of 4,000- 8,000Angstrom . Since the main conducting layer 18 includes 0.5-4% Cu or Mg, electromigration can be prevented. Since the TiN layer 17 is provided, the deposition of Si to the wiring from a polycrystal Si layer 15 can be confined only to the layer 16, when heat treatment is performed at 400-450 deg.C during a process after the formation of the wiring. Different from conventionally used Ti-W, TiN does not have reaction against Si. Therefore Si is not deposited on a shallow diffused layer 13 such as an emitter, and the damage of P-N junction can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to the structure of a semiconductor device, and particularly to the structure of an aluminum electrode wiring provided in a semiconductor device having a shallow junction.

(b) Background of the technology An n-type diffusion region with a shallow junction, such as the emitter layer of a highly integrated bipolar IC, is usually made of phosphosilicate glass (which is deposited on the surface of a p-type semiconductor substrate through four layers of polycrystalline silicon). P.S.
G) is formed by solid phase-solid phase diffusion of thin (P) (washing, de-emitter method). When connecting the aluminum (Al) wiring to the shallow diffusion layer,
In order to prevent Al from penetrating into the diffusion layer and destroying the junction, Al wiring turns are formed on the polycrystalline silicon layer. Therefore, in such a structure, A[
Since a polycrystalline silicon layer is disposed over the entire area under the wiring pattern, many problems occur during the heat treatment process at about 400 to 450 [°C] after the wiring pattern is formed, such as the growth of a surface protection insulating film. There is a problem in that crystalline silicon dissolves into the Al wiring at supersaturation and precipitates, increasing the wiring resistance.

On the other hand, as ICs become more highly integrated, the wiring becomes finer, and the density of current flowing through the wiring increases.) In wiring made of pure Al, when electricity is applied for a long time, the well-known electromagnetic
There is a problem that wire breakage occurs due to the migration effect, and as a means to reduce the electro-migration effect and increase the wiring life, copper (Cu) or magnesium (Mg) is contained in the layer at an amount of 4% or less. Al--Mg alloy interconnects made of Al--Cu alloy interconnects have come to be widely used.

However, when the Al-Cu alloy wiring or 1-Mg alloy wiring is formed on the polycrystalline silicon layer of the IC substrate on which shallow junctions have been formed by the method described above, the wiring is removed by heat treatment after wiring formation as described above. As the precipitation of silicon crystals inside is promoted and the shape of the precipitated crystals becomes larger than in the case of pure Al, wiring resistance increases significantly and I
A problem arises in that the operating speed of C is reduced. Figure 1 shows Al-Cu or 1-Mg with precipitated silicon crystals.
This is a schematic diagram of alloy wiring, and 1 in the figure is Al-Cu.
or Al-Mg alloy wiring, 2 is silicon precipitated crystal,
3 represents a polycrystalline silicon layer.

(c) Prior art and problems Therefore, when using Al-Cu alloy wiring or Al-Mg alloy wiring, in order to confine the precipitated silicon crystal only in the lower layer in contact with the polycrystalline silicon layer, the conventional technique shown in Fig. 2 is used. For example, a titanium-tungsten (Ti-W) alloy layer 4, which is often used as a high-melting point wiring material, is placed near the lower layer of the Ad-Cu alloy arrangement 9.
A structure in which blocking layers with a thickness of about 500 CX) were sandwiched was tried, and precipitation of silicon crystals in areas other than the lower layer 5 of the Al--Cu alloy wiring 1 was prevented.

However, in this structure, the reactivity of the Ti-W alloy with silicon is extremely strong, so even the silicon in the shallow emitter layer below the polycrystalline silicon layer at the electrode contact part is eaten away by the Ti-W alloy layer. However, there is a problem in that the junction of the emitter layer is destroyed and an emitter head (E-B) short failure is induced.

(d) Purpose of the Invention In view of the above-mentioned problems, the present invention provides a jW! that has a silicon block layer near the bottom that is not reactive to silicon and has a sufficient shielding effect. - It provides a wiring structure consisting of Cu or Al-Mg layer, and its purpose is to improve the quality and reliability of wiring, and to improve the quality and reliability of semiconductor ICs.
The goal is to improve the performance and reliability of

(e) At the dawn of the invention, the present invention provides a semiconductor device comprising a first layer made of aluminum or an aluminum alloy, a second layer made of titanium nitride, and an aluminum-copper O alloy or an aluminum-magnesium alloy. The third layer is characterized in that it includes metal wiring that is sequentially laminated from the bottom.

(f) Examples of the Invention The present invention will now be described in detail with reference to the drawings.

FIG. 3 is a cross-sectional view showing an embodiment of a metal wiring structure according to the present invention, and FIG. 4 is a cross-sectional view of essential parts of an embodiment of a semiconductor device according to the present invention.

The metal wiring, which is a feature of the present invention, is a silicon (St) substrate and an epitaxial layer that the wiring directly contacts.

Pure Al or Al-Cu for making ohmic contact with semiconductor substrates such as diffusion layers and polycrystalline St layers;
The first layer consists of an AA alloy layer such as Al-Mg, and the titanium nitride (TiN
), and the third layer, which is the main conductive layer and is made of an A1 alloy layer such as Al-Cu or Al-Mg to prevent migration of Al, are laminated sequentially from the bottom. It has become.

Figure 3 shows its cross section. The first layer for making ohmic contact has a thickness of about 500 to 1,500 [ku], and the second layer to prevent Si diffusion has a thickness of about 500 to 1,500 [ku].
The third layer, which is the main conductive layer, is formed to have a thickness of about 4000 to 8000 [X].

Note that in order to prevent the Al--Cu or Al--Mg structure from becoming non-uniform, an A1 alloy containing about 0.5 to 4 [chi] of Cu or Mg is desirable.

In addition, the reason why A4 alloys such as Al-Cu and A/-Mg are included in the material of the first layer is to simplify the formation process by using the same material as the third layer, and it is functionally pure Al. is sufficient.

Furthermore, the TiN layer used as the Si shielding layer has a thickness of 80 [μ
Although it has a relatively high resistivity of about Ω-Cm, since the layer thickness is extremely thin, the effect on wiring resistance is extremely small.

FIG. 4 shows a cross section of a main part of a bipolar IC having a shallow emitter layer on which the above wiring is formed, in which 11 is an n-type collector region, 12 is a p-type base region, and 13 is an n-type emitter region. , 14 is a silicon dioxide (Sin2) film, 15 is a polycrystalline Si layer, 16 is an Al-Cu alloy ohmic contact layer, 17 is a TiN layer, 18 is A7-C
The U alloy Φ main conductive layer, 19 is an emitter wiring, 20 is a base wiring, and 21 is a cover insulating film.

And emitter wiring 19. When forming metal wiring having the structure of the present invention, such as the base wiring 20, the Al-Cu alloy layer 16. A 711-Cu alloy layer 18 is sequentially laminated on one TiN layer, and the laminated film is etched all at once by a dry etching method using a chlorine gas such as boron trichloride (B CAR) + carbon tetrachloride <CC, . All you have to do is pattern.

Note that it can also be formed by reactive sputtering of Ti in an atmosphere of 7 elements < N2) on one TiN layer or in an atmosphere containing N2 and argon (Ar).

(g) As described in detail, the aluminum wiring in the present invention is
An ohmic contact layer made of aluminum or aluminum alloy and a main conductive layer made of aluminum-copper or aluminum-magnesium alloy that prevents migration of sialuminium are separated by a titanium nitride layer that prevents silicon diffusion. Therefore, the silicon that has melted into the ohmic contact layer is confined and precipitated within the ohmic contact layer, and no silicon is precipitated within the main conductive layer.

Therefore, according to the present invention, an aluminum wiring having low wiring resistance and preventing disconnection due to aluminum migration is provided, thereby improving the performance and reliability of a semiconductor device.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the state of silicon crystal precipitation in aluminum-copper or aluminum-magnesium alloy wiring, Fig. 2 is a cross-sectional view of conventional aluminum alloy wiring, and Fig. 3 is a metal wiring according to the present invention. 4 is a cross-sectional view of a wall of an embodiment of the semiconductor device of the present invention. In the diagram, 11 is an n-type collector region, 12 is a p-type base region, 13 is an n-type emitter region, 14 is a silicon dioxide film, 15 is a polycrystalline silicon layer, 16 is an aluminum-copper alloy ohmic contact layer, 17 is a titanium nitride layer, 18 is an aluminum-copper alloy main conductive layer, 19 is the emitter wiring, 20 is the base wiring, and 21 is the cover insulating film. closed

Claims (1)

[Claims] A first layer made of aluminum or an aluminum alloy, a second layer made of titanium nitride, and an aluminum-copper layer.
1. A semiconductor device comprising metal wiring in which a third layer made of an alloy or an aluminum-magnesium alloy is laminated sequentially from the bottom.