JPH07130854A - Wiring structure body and its forming method - Google Patents

Abstract

PURPOSE:To suppress the movement to aluminum plug of aluminum of a lower- layer wiring layer without forming barrier metal layer consisting of TiON or TiN with a high specific resistance between aluminum lower-layer wiring layer and the aluminum plug when electrically connecting the aluminum plug to the aluminum lower-layer wiring layer. CONSTITUTION:In the title wiring structure body which is constituted of aluminum lower-layer wiring layer 1, an insulation layer 2 which is formed on it and has a connection hole A for electrical connection to the aluminum lower- layer wiring layer 1, TiAl3 layer 7 is formed between the aluminum lower-layer wiring layer 1 at the bottom of at least the connection hole A and the aluminum plug 4a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring structure formed in a semiconductor device. More specifically, in a wiring structure in which an insulating layer is formed on an aluminum-based lower wiring layer and an aluminum-based plug is formed on the insulating layer, a void between the aluminum-based lower wiring layer and the aluminum-based plug is formed. The present invention relates to a wiring structure.

[0002]

2. Description of the Related Art Conventionally, a metal plug filling a wiring layer or a connection hole of a semiconductor device is formed by an ambient temperature sputtering method using an aluminum material having a low specific resistance and a low material cost.

Meanwhile, as the degree of integration of semiconductor devices has advanced, the diameter of the connection holes for conducting the lower wiring layer and the upper wiring layer of the semiconductor device has become finer and the aspect ratio thereof has become higher. When an aluminum-based material is embedded in such a fine connection hole, sufficient step coverage cannot be achieved by simply embedding the aluminum-based material by a room temperature sputtering method as in the conventional case.

Therefore, as a method of burying an aluminum-based material in a fine connection hole, attention has been paid to a high temperature sputtering method and a reflow method capable of simultaneously forming a metal plug and a flat upper wiring layer. The high-temperature sputtering method is a technique for reflowing the aluminum-based material deposited on the semiconductor substrate to fill the connection holes by heating the semiconductor substrate near the melting point of the aluminum-based material when sputtering the aluminum-based material. And the reflow method is
This is a technique in which a semiconductor substrate is sputtered with an aluminum-based material at a normal sputtering temperature, and then the semiconductor substrate is heated to near the melting point of the aluminum-based material to reflow the deposited aluminum-based material to fill the connection holes. In this case, in order to improve the embedding property of the aluminum-based material, a Ti layer having a good wettability with the aluminum-based material is generally formed as a base over the entire surface of the lower wiring layer and the insulating layer.

FIG. 7 shows a wiring structure formed by embedding an aluminum-based material in fine connection holes in this way.
As shown in the figure, this wiring structure has a lower wiring layer 1,
Insulating layer 2 made of SiO ₂ or PSG having connection hole A, Ti formed on the surface of insulating layer 2 and the inner surface of connection hole A
The layer 3 and the aluminum-based plug 4a embedded in the connection hole A and the aluminum-based upper wiring layer 4b are included. A TiAl alloy layer 5 formed by the reaction of Ti and Al is formed at the boundary between the Ti layer 3 and the aluminum-based plug 4a or the aluminum-based upper wiring layer 4b.

[0006]

However, when forming the wiring structure as shown in FIG. 7, when the lower wiring layer 1 is made of an aluminum-based material, the lower wiring layer 1 and the Ti layer 3 are separated from each other. Under the condition that they react with each other, for example, when an aluminum-based plug is formed by using a high temperature sputtering method or a reflow method, voids are formed in the lower wiring layer 1 as described below. There is a problem that the reliability of wiring cannot be ensured. That is, as shown in FIG. 8A, an insulating layer 2 made of SiO ₂ or the like having a connection hole A is formed on a lower wiring layer 1 made of an aluminum material, and a Ti layer 3 is formed on the entire surface as a base layer. After that, when an aluminum-based alloy is formed by high-temperature sputtering, the aluminum-based material forming the lower wiring layer 1 diffuses into the Ti layer 3 while expanding due to heating, as shown in FIG. Finally, the aluminum-based material that reaches the surface of the Ti layer 3 and further constitutes the lower wiring layer 1 is the aluminum-based plug 4a as shown by the arrow in the figure.
There is a problem in that the voids B are diffused and sucked up by the voids and voids B are formed in the lower wiring layer 1 as shown in FIG. 8C.

Similarly, the reflow method also has a problem that voids B are formed in the lower wiring layer 1 by heating in the reflow process after forming the aluminum type plug 4a.

In order to solve this problem, as shown in FIG. 9, in order to prevent the reaction between the aluminum-based lower wiring layer 1 and the Ti layer 3b, TiON conventionally used as a material for an antireflection film. Alternatively, it is proposed that the barrier metal layer 6 made of TiN is arranged so as to be sandwiched between the aluminum-based lower wiring layer 1 and the aluminum-based plug 4a and also between the Ti layers 3a and 3b (Japanese Patent Application No. Hei 5 (1999) -135242). −
173701 specification). Here, the barrier metal layer 6 and the Ti layer 3a are formed in advance on the aluminum lower wiring layer 1 before the connection hole A is formed in the insulating layer 2. The Ti layer 3a is a layer for preventing the aluminum-based lower wiring layer 1 from being rendered nonconductive by the barrier metal layer 6, and the Ti layer 3b is provided for improving the burying property of the aluminum material. .

However, since TiON, TiN and the like which form the barrier metal layer 6 have a high specific resistance, their thickness cannot be increased in order to suppress an increase in wiring resistance, and the wiring layer thickness must be suppressed. Therefore, the thickness is set to a thickness necessary for preventing the reaction between the lower wiring layer 1 and the Ti layer 3b. Therefore, the thickness of the barrier metal layer 6 is usually about 20-
It is very thin, 30 nm. Therefore, it is very difficult to stop the etching at the barrier metal layer 6 when the connection hole is formed by etching, and the connection hole A may penetrate the barrier metal layer 6. Further, the barrier metal layer 6 may be cracked due to stress,
In that case, the aluminum-based lower wiring layer 1 and the Ti layer 3b react with each other through cracks, and as a result, the lower wiring layer 1
There was a problem that voids were formed in the.

There is also a problem that the wettability of the aluminum-based material of the Ti layer 3b on the barrier metal layer 6 is lower than that when the barrier metal layer 6 is not present.

By the way, in FIG. 9, the barrier metal layer 6 is formed on the Ti layer 3a in advance before the connection hole A is formed, but the barrier metal layer 6 is connected after the connection hole sub-portion is formed in the insulating layer 2. It is also possible to form it inside the hole by using the CVD method or the like. However, the coverage to the bottom of the fine connection hole of the barrier metal layer is not sufficient,
Therefore, there is a problem that the reaction between the aluminum-based lower wiring layer and the Ti layer cannot be effectively prevented.

The present invention is intended to solve the above-mentioned problems of the prior art, and when the aluminum-based plug is electrically connected to the aluminum-based lower wiring layer, TiON has a high specific resistance therebetween. Alternatively, it is possible to suppress the movement of aluminum of the lower wiring layer to the aluminum-based plug without forming a barrier metal layer made of TiN, so that there is no void in the lower wiring layer and there is no disconnection of the Al wiring. It is an object to provide a body and a method for forming the body.

[0013]

Means for Solving the Problems The present inventor has achieved the above-mentioned object by forming a TiAl ₃ layer in advance between the aluminum-based lower wiring layer at the bottom of the connection hole and the aluminum-based plug. Heading out, the present invention has been completed.

That is, according to the present invention, an aluminum-based lower wiring layer, an insulating layer laminated on the aluminum-based lower wiring layer, and an insulating layer having a connection hole for establishing conduction to the aluminum-based lower wiring layer, and a connection hole. In a wiring structure including an aluminum-based plug embedded in the wiring, a TiAl ₃ layer is formed at least between the aluminum-based lower wiring layer at the bottom of the connection hole and the aluminum-based plug. Provide a structure.

The present invention also provides a method of forming a wiring structure as described above, wherein: TiAl is formed on the aluminum-based lower wiring layer.
A step of forming _three layers; a step of forming an insulating layer on the TiAl ₃ layer; a step of forming a connection hole in the insulating layer for establishing conduction to the aluminum-based lower wiring layer until reaching the TiAl ₃ layer; and There is provided a forming method including a step of burying an aluminum-based material in a connection hole to form an aluminum-based plug.

The present invention further provides the above-mentioned method for forming a wiring structure: a step of forming a Ti layer on an aluminum-based lower wiring layer; the aluminum-based lower wiring layer and the Ti layer are heated to react with each other to form a Ti layer. step of forming an insulating layer on the generated TiAl ₃ layer on; the processes and TiAl _3-layer insulating layer and openings to the connection hole to obtain conductivity to aluminum-based lower wiring layers reaches the TiAl ₃ layers And a step of burying an aluminum-based material in the connection hole to form an aluminum-based plug.

Further, the present invention provides the above-described method for forming a wiring structure: a step of forming an insulating layer on the aluminum-based lower wiring layer; connecting the insulating layer to the aluminum-based lower wiring layer for electrical connection. A step of forming a hole until reaching the aluminum-based lower wiring layer; a step of forming a Ti layer at least at the bottom of the connection hole by a CVD method; heating the aluminum-based lower wiring layer and the Ti layer to react with each other There is provided a forming method characterized by including a step of forming a Ti layer at the bottom portion into a TiAl ₃ layer; and a step of burying an aluminum material in a connection hole to form an aluminum plug.

Further, in the present invention, in the above-described method for forming a wiring structure, the step of forming an insulating layer on the aluminum-based lower wiring layer; connecting the insulating layer to the aluminum-based lower wiring layer for conduction. A step of forming a hole until reaching the aluminum-based lower wiring layer; a step of forming a TiAl ₃ layer by a CVD method on at least the bottom of the connection hole; and a step of burying an aluminum-based material in the connection hole to form an aluminum-based plug The present invention provides a forming method comprising:

The present invention will be described in detail below with reference to the drawings. In the drawings, the same reference numerals represent the same or equivalent constituent elements.

First, FIG. 1 shows a sectional view of a wiring structure of the present invention in a preferred embodiment. This wiring structure includes an aluminum-based lower wiring layer 1, an insulating layer 2 made of SiO ₂ having a connection hole A, and TiAl ₃ formed on the bottom of the connection hole A.
T formed on the surfaces of the layer 7 and the insulating layer 2 and the inner surface of the connection hole A
The i-layer 3 includes an aluminum-based plug 4a embedded in the connection hole A and an aluminum-based upper wiring layer 4b.
Further, an antireflection film 9 such as TiON or TiN, which is provided as necessary, is formed on the aluminum-based upper wiring layer 4b.

As described above, the wiring structure of the present invention has the TiAl ₃ layer 7 between the aluminum-based lower wiring layer 1 and the aluminum type plug 4a. This TiAl ₃
Layer 7 is a stable compound formed by the reaction of titanium and aluminum, the TiAl ₃ layer 7 no longer reacts with aluminum. Therefore, even if the aluminum-based lower wiring layer 1 is heated near the melting point of the aluminum-based alloy,
Aluminum contained therein does not react with the TiAl ₃ layer 7 and therefore does not diffuse into the aluminum-based plug 4a. As a result, it is possible to prevent the occurrence of voids in the aluminum-based lower wiring layer 1 and prevent disconnection of the aluminum-based wiring layer without forming a barrier metal layer made of TiON or TiN, thereby improving heat resistance. Can be made. In addition, TiAl has a significantly smaller specific resistance than TiON or TiN, so TiON
Alternatively, the wiring structure has a low resistance as compared with the case where a via metal layer made of TiN is formed. Also, the wettability of the aluminum-based material with respect to the Ti layer can be improved.

In the embodiment shown in FIG. 1, TiAl ₃
Although the layer 7 exists only on the aluminum-based lower wiring layer 1, it may also exist on the surface and side surfaces of the insulating layer 2, that is, on the inner wall of the connection hole A, as shown in FIG. When the upper wiring layer is further laminated on the aluminum upper wiring layer 4b via the connection hole, it is preferable that the TiAl ₃ layer is laminated again on the aluminum upper wiring layer 4b.

In addition to the above, as an aspect of the wiring structure of the present invention, the aluminum-based upper wiring layer 4b may be omitted in the aspects shown in FIGS.

When a high temperature sputtering method or a reflow method is used to fill the connection hole A with an aluminum-based material, the aluminum-based plug 4a, the aluminum-based upper wiring layer 4b, and the Ti layer 3 are bordered with each other. Is Ti and A
A TiAl alloy layer is formed by the reaction with 1, but such a TiAl alloy layer may be formed in the wiring structure of the present invention.

Next, a method of forming the wiring structure of the present invention will be described with reference to FIGS.

FIG. 3 shows that before the connection hole A is formed, TiA is formed.
This is a method characterized in that a TiAl ₃ layer is formed in advance on the aluminum-based lower wiring layer 1 by a sputtering method with a target of l ₃ as a target. A Ti layer 3c is first formed on the lower wiring layer 1 by a sputtering method using Ti as a target, and the Ti layer 3c and the aluminum-based lower wiring layer 1 are reacted to form a TiAl ₃ layer 7 in advance. 5 is a method of forming a connection hole A in the insulating layer 2 on the aluminum-based lower wiring layer 1 and then forming the Ti layer 3c.
Is formed on the entire surface by the CVD method, and the Ti layer 3c is reacted with the aluminum-based lower wiring layer 1 to form the TiAl ₃ layer 7
And a method of forming
Is a method characterized in that after the connection hole A is formed in the insulating layer 2 on the aluminum-based lower wiring layer 1, the TiAl ₃ layer 7 is formed at the bottom of the connection hole A by the CVD method.

In the case of the forming method shown in FIG. 3, first, the TiAl ₃ layer 7 is formed on the aluminum-based lower wiring layer 1 by a sputtering method or a CVD method using TiAl ₃ as a target. The insulating layer 2 is formed on the TiAl ₃ layer 7 and the holes are formed by photolithography, but in order to improve the patterning property at that time, on the TiAl ₃ layer 7, TiON or TiN is used. It is preferable to form an antireflection film 9 (FIG. 3A).

Next, the insulating layer 2 made of SiO ₂ or the like is formed on the TiAl ₃ layer 7 by the sputtering method or the like (FIG. 3).
(B)).

Next, the TiAl ₃ layer 7 is formed with a connection hole A in the insulating layer 2 for establishing electrical connection to the aluminum-based lower wiring layer 1.
The holes are opened by the photolithography method until the temperature reaches (Fig. 3 (c)).

Next, an aluminum-based material is embedded in the connection hole A to form an aluminum-based plug 4a. Before the filling, the entire surface, that is, the inner surface of the connection hole A and the surface of the insulating layer 2 is improved for the purpose of improving the filling characteristics. It is preferable to form the Ti layer 3 on the substrate (FIG. 3D). And this T
An aluminum material is embedded in the connection hole A in which the i layer 3 is formed by a sputtering method or the like to form an aluminum plug 4a. At this time, the aluminum-based upper wiring layer 4b may be simultaneously formed. If necessary, an antireflection film 8 made of TiON or TiN may be formed on the aluminum-based upper wiring layer 4b (FIG. 3).
(E)). In this way, the wiring structure of the present invention is obtained.

In the method shown in FIG. 3, the aluminum-based material is embedded in the connection hole A and the aluminum-based plug 4 is used.
By performing the high temperature sputtering method or the reflow method when forming a, it is possible to bury the aluminum-based material in the fine connection holes having a high aspect ratio with good coverage.

In the case of the forming method of FIG. 4, the difference from the forming method of FIG. 3 is that the T-layer is directly formed on the aluminum-based lower wiring layer 1.
Instead of forming the iAl ₃ layer, the Ti layer 3c is first formed, and then the antireflection film 9 made of TiON or TiN is formed.
(FIG. 4 (a)) and heat-treated, eg RT
Ti after A (Rapid Thermal Annealing) treatment
The point is to react the layer 3c with the aluminum-based lower wiring layer 1 to form a TiAl ₃ layer 7 as shown in FIG. 4 (b). With such a process, the effect that the TiAl ₃ layer is self-formed is obtained. After that, the wiring structure of the present invention is obtained by following the same steps as those shown in FIGS. The Ti layer 3c can be formed by a sputtering method or a CVD method using Ti as a target.

In the case of the forming method of FIG. 5, first, the insulating layer 2 is formed on the aluminum-based lower wiring layer 1 by a conventional method (FIG. 5A).

Next, a connection hole A for establishing electrical connection to the aluminum-based lower wiring layer 1 is formed in the insulating layer 2 by photolithography until it reaches the aluminum-based lower wiring layer 1 (FIG. 5B). ).

Next, a Ti layer 3c is formed on at least the bottom of the connection hole A by the CVD method. In this case, generally, the Ti layer 3c is formed on the entire surface (FIG. 5C).

Next, the aluminum-based lower wiring layer 1 and Ti
The layer 3c and the layer 3c are heated and reacted by RTA treatment or the like to form the Ti layer at the bottom of the connection hole A as the TiAl ₃ layer 7 (FIG. 5).
(D)).

Next, an aluminum-based material is embedded in the connection hole A to form an aluminum-based plug 4a. Before the filling, an excess T is formed to remove the overhang portion.
The i layer 3c is removed by selective etching (FIG. 5 (e)), and T is again formed on the entire surface, that is, the inner surface of the contact hole A and the surface of the insulating layer 2 for the purpose of improving the filling characteristics of the aluminum-based material.
It is preferable to form the i layer 3 (FIG. 5F).
Then, an aluminum material is embedded in the connection hole A in which the Ti layer 3 is formed by a sputtering method or the like to form an aluminum plug 4a. At this time, the aluminum-based upper wiring layer 4b may also be formed at the same time. If necessary, TiON may be formed on the aluminum-based upper wiring layer 4b.
Alternatively, the antireflection film 8 made of TiN or the like may be formed (FIG. 5G). In this way, the wiring structure of the present invention is obtained.

In the method shown in FIG. 5, the aluminum-based material is embedded in the connection hole A and the aluminum-based plug 4 is used.
By performing the high temperature sputtering method or the reflow method when forming a, it is possible to bury the aluminum-based material in the fine connection holes having a high aspect ratio with good coverage.

The method shown in FIG. 6 differs from the method shown in FIG. 5 in that the insulating layer 2 is formed on the aluminum-based lower wiring layer 1 and the connection hole A is formed, and then the aluminum-based lower wiring layer is formed. 1. Instead of forming a Ti layer on
in that formed directly on the bottom of at least the connection hole A to l _3-layer 7 (Fig. 6). With such a process, an effect of suppressing an increase in wiring resistance value can be obtained. After that, the wiring structure of the present invention is obtained according to the same steps as those in FIGS.

The wiring structure and the method of forming the same according to the present invention described above are particularly suitable for the case where an aluminum-based lower wiring layer inside a highly integrated semiconductor device is electrically connected by a fine and high aspect ratio aluminum-based plug. It is a thing.

[0041]

In the present invention, the TiAl ₃ layer is formed between the aluminum-based lower wiring layer and the aluminum-based plug. This TiAl ₃ layer is a stable compound formed by the reaction of titanium and aluminum,
No longer reacts with aluminum. Therefore, even if the aluminum-based lower wiring layer is heated to near the melting point of the aluminum-based alloy, the aluminum in the aluminum-based lower wiring layer does not react with the TiAl ₃ layer, and therefore,
The aluminum-based lower wiring layer does not diffuse into the aluminum-based plug. This makes it possible to prevent the occurrence of voids in the aluminum-based lower wiring layer 1. Further, since the via metal layer made of TiON or TiN is not formed, it is possible to realize a wiring structure having low resistance.

[0042]

The present invention will be described in more detail below with reference to examples.

Example 1 A 100-nm-thick Ti layer (a layer for preventing Al diffusion into a silicon substrate) layer was laminated on a silicon substrate under the following film forming conditions by a single-wafer type magnetron sputtering apparatus. Further, an AlSi layer (aluminum-based lower wiring layer) having a thickness of 500 nm was formed.

Ti layer (layer for preventing diffusion of Al into silicon substrate) Sputtering film forming conditions Target Ti DC power 4 kW Gas type Ar, 100 SCCM pressure 0.4 Pa Substrate heating temperature 150 ° C. AlSi layer (aluminum type lower wiring layer) ) Sputtering film forming conditions (high temperature sputtering method) Target Al-1% Si DC power 10 kW Gas system Ar, 100 SCCM Film forming rate 0.6 μm / min. Pressure 0.4 Pa Substrate heating temperature 500 ° C. A 70 nm thick TiAl ₃ layer was formed on this AlSi layer under the following film forming conditions according to the process shown in FIG.
An iON layer (antireflection film) was formed.

TiAl ₃ layer (reaction preventing layer of Ti and Al) Sputtering film forming conditions Target TiAl ₃ DC power 10 kW Gas system Ar, 100 SCCM pressure 0.4 Pa Substrate heating temperature 150 ° C. TiON layer (antireflection film) Sputtering film formation Conditions Target TiON DC power 5 kW Gas system Ar, 30 SCCM N ₂ + 6% O ₂ , 70 SCCM Pressure 0.4 Pa Substrate heating temperature 150 ° C. A SiO ₂ insulating layer is formed on the TiON layer thus formed by a conventional method. , TiAl ₃ layer was opened by photolithography. The depth of the connection hole was 0.5 μm and the opening diameter was 0.7 μm.

Then, a Ti layer for improving the wettability of the aluminum-based material is formed by the single-wafer type magnetron sputtering apparatus under the same film forming conditions as described above, and then an AlSi layer is laminated to form an aluminum-based plug. Along with the formation, an aluminum-based upper wiring layer was formed, and an antireflection film made of TiON was further formed to obtain a wiring structure having the structure shown in FIG. 3 (e). The aluminum-based lower wiring layer of the obtained wiring structure had no voids, and was a highly reliable and low-resistance aluminum-based wiring structure having excellent heat resistance.

A bias voltage may be applied to the silicon substrate during high temperature sputtering of the AlSi layer forming the aluminum-based lower wiring layer, the aluminum-based plug or the aluminum-based upper wiring layer. Further, the reflow method may be adopted instead of the high temperature sputtering method, and the film forming conditions in that case are as follows.

AlSi layer (reflow method) Sputtering film forming conditions Target Al-1% Si DC power 20 kW Gas system Ar, 100 SCCM Film forming rate 1.2 μm / min. Pressure 0.4Pa Substrate heating temperature 150 ° C Reflow condition Heating method Substrate backside gas heating method Heating temperature 500 ° C Heating time 2 min. Gas system Ar, 100 SCCM Substrate backside pressure 1064 Pa (8.0 Torr) In addition, the substrate backside gas heating method is that a heater block installed on the backside of the substrate is heated to a predetermined temperature, and between this heater block and the backside of the substrate. This is a method of heating the substrate by introducing an assist gas such as Ar. A general method such as a lamp heating method may be used instead of the substrate backside gas heating method.

Example 2 Instead of forming the TiAl ₃ layer by the sputtering method according to the process of FIG.
By repeating Example 1 except that a Ti layer with a thickness of nm is formed and a TiAl ₃ layer is formed by further performing a lamp annealing treatment (heating temperature 500 ° C., heating time 1 minute, gas-based Ar 5 liter / minute). The wiring structure of the present invention was obtained. The aluminum-based lower wiring layer of the obtained wiring structure had no voids, and was a highly reliable and low-resistance aluminum-based wiring structure having excellent heat resistance.

Example 3 By repeating the example 2 except that a furnace annealing treatment (heating temperature of 500 ° C., heating time of 30 minutes, gas system N ₂ liter / minute) is performed instead of the lamp annealing treatment of the embodiment 2. The wiring structure of the present invention was obtained. The aluminum-based lower wiring layer of the obtained wiring structure had no voids, and was a highly reliable and low-resistance aluminum-based wiring structure having excellent heat resistance.

Example 4 The process of Example 2 was performed by using the Ti sputtering chamber 100 and the Al alloy sputtering chamber 1 as shown in FIG.
01, RTA By using a multi-chamber type device (cluster tool) having a plurality of chambers 102, a pre-clean chamber 103, a load lock chamber 104, and transfer chambers 105 and 106, each layer is continuously exposed without being exposed to the atmosphere. Formed. As a result, the adverse effect of oxygen on the Ti layer and the like can be eliminated, and a wiring structure having higher reliability was obtained.

Example 5 According to the process of FIG. 5, an insulating layer is formed in the same manner as in Example 1 on the AlSi layer (aluminum-based lower wiring layer) formed in the same manner as in Example 1, and the AlSi layer is further formed. Form a connecting hole that reaches.

Next, after removing the natural oxide (alumina) on the Al surface by sputter etching by Ar reverse sputtering, the bottom of the connection hole is continuously formed by collimation sputtering under the following sputtering conditions or ordinary sputtering. A Ti layer having a thickness of 5 to 50 nm is formed.

Ti sputter condition target
Ti DC power 3 to 10 kW Gas system Ar, 50 to 100 SCCM Pressure 0.5 Pa Substrate heating temperature 200 to 400 ° C. Next, at 400 to 500 ° C. in Ar or H ₂ atmosphere 30
By performing heat treatment for 120 seconds, the Ti layer at the bottom of the contact hole reacts with Al in the aluminum-based lower wiring layer to change into a TiAl ₃ layer.

Next, unreacted T on the surface of the insulating layer and on the side wall of the contact hole.
The i layer was treated with ammonia hydrogen peroxide (NH ₃ : H ₂ 0 ₂ : H ₂ 0 =
It is selectively etched away at 1: 2: 2).

Next, in the same manner as in Example 1, a Ti layer for improving the wettability of the aluminum-based material is formed, and then an AlSi layer is laminated to form an aluminum-based plug and an upper wiring layer. Then, an antireflection film made of TiON is further formed to obtain the wiring structure having the structure shown in FIG. The wiring structure obtained in this manner also has no voids in the aluminum-based lower wiring layer, is highly reliable in heat resistance, and has low resistance.

Example 6 After the natural oxide (alumina) on the Al surface was sputter-etched and removed by Ar reverse sputtering according to the process described in FIG. 6, a TiAl ₃ layer instead of the Ti layer was continuously formed in the connection hole. 2 is repeated except that a film is formed on the bottom of the substrate by a sputtering method and no heat treatment is performed.
A wiring structure of the present invention as shown in is obtained. The wiring structure obtained in this manner also has no voids in the aluminum-based lower wiring layer, is highly reliable in heat resistance, and has low resistance.

Example 7 After natural oxide (alumina) on the Al surface was removed by sputter etching by Ar reverse sputtering, TiAl ₃
Instead of depositing by sputtering a layer on the bottom of the continuously connecting hole, continuously _{[(i-C 4 H 9} ) 3 AlH]
Alternatively, a wiring structure of the present invention is obtained in the same manner as in Example 6 except that a TiAl ₃ layer is formed by a CVD method using [(CH ₃ ) ₂ AlH], TiCl ₄ and H ₂ under the following conditions. . The wiring structure obtained in this manner also has no voids in the aluminum-based lower wiring layer, is highly reliable in heat resistance, and has low resistance.

TiAl ₃ CVD film forming conditions Substrate temperature 400 to 500 ° C. [(i-C ₄ H ₉ ) ₃ AlH] or [(CH ₃ ) ₂ Al
H] flow rate 5 to 50 SCCM TiCl ₄ flow rate 5 to 30 SCCM H ₂ flow rate 50 to 300 SCCM

[0060]

According to the present invention, when an aluminum-based plug is electrically connected to an aluminum-based lower wiring layer, a barrier metal layer made of TiON or TiN having a high specific resistance is not formed between them to form an aluminum-based plug. It is possible to suppress the movement of the aluminum of the lower wiring layer to the aluminum-based plug, prevent the occurrence of voids in the lower wiring layer of the aluminum-based wiring layer, and realize a wiring structure of low-resistance aluminum-based wiring without disconnection.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a wiring structure of the present invention.

FIG. 2 is a cross-sectional view of a wiring structure of the present invention.

FIG. 3 is a process drawing of a method for forming a wiring structure of the present invention.

FIG. 4 is a process drawing of the method for forming a wiring structure of the present invention.

FIG. 5 is a process drawing of the method for forming a wiring structure of the present invention.

FIG. 6 is an explanatory diagram of a method for forming a wiring structure of the present invention.

FIG. 7 is a cross-sectional view of a conventional wiring structure on a silicon substrate.

FIG. 8 is an explanatory diagram of a problem of a conventional wiring structure.

FIG. 9 is a cross-sectional view of a conventional wiring structure.

FIG. 10 is a schematic plan view of a cluster tool.

[Explanation of symbols]

1 Aluminum-based lower wiring layer 2 Insulating layer 3, 3a, 3b, 3c Ti layer 4a Aluminum-based plug 4b Aluminum-based upper wiring layer 5 TiAl alloy layer 6 Barrier metal layer 7 TiAl ₃ layer 8, 9 Antireflection film A Connection hole B Void

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[Procedure amendment]

[Submission date] July 20, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0055

[Correction method] Change

[Correction content]

Next, the unreacted Ti layer on the surface of the insulating layer and the sidewall of the contact hole is treated with ammonia hydrogen peroxide (NH ₄ OH : H ₂ 0 ₂ : H
₂₀ : 1: 2: 2) selectively removes by etching.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/88 R

Claims (10)

[Claims] 1. An aluminum-based lower wiring layer and an insulating layer laminated on the aluminum-based lower wiring layer, the insulating layer having a connection hole for electrically connecting to the aluminum-based lower wiring layer, and embedded in the connection hole. In a wiring structure including an aluminum-based plug, at least Ti is provided between the aluminum-based lower wiring layer at the bottom of the connection hole and the aluminum-based plug.
A wiring structure, wherein an Al ₃ layer is formed. 2. The wiring structure according to claim 1, wherein an aluminum-based upper wiring layer is formed on the aluminum-based plug. 3. The method for forming a wiring structure according to claim 1, wherein a step of forming a TiAl ₃ layer on the aluminum-based lower wiring layer; a step of forming an insulating layer on the TiAl ₃ layer; and an aluminum layer on the insulating layer. A step of forming a connection hole for establishing electrical connection to the lower wiring layer of the system until reaching the TiAl ₃ layer; and a step of burying an aluminum material in the connection hole to form an aluminum plug. Forming method. 4. The forming method according to claim 3, wherein when the aluminum-based material is embedded in the connection hole to form the aluminum-based plug, the high-temperature sputtering method or the reflow method is used. 5. The method for forming a wiring structure according to claim 1, wherein the step of forming a Ti layer on the aluminum-based lower wiring layer; the aluminum-based lower wiring layer and the Ti layer are heated to react with each other to form a Ti layer. step of forming an insulating layer on the generated TiAl ₃ layer on; step of the TiAl _3-layer insulating layer, the step of opening a connection hole for taking conduction to an aluminum-based lower wiring layers to reach the TiAl ₃ layers And a step of burying an aluminum-based material in the connection hole to form an aluminum-based plug. 6. The forming method according to claim 5, wherein when the aluminum-based material is embedded in the connection hole to form the aluminum-based plug, the high-temperature sputtering method or the reflow method is used. 7. The method of forming a wiring structure according to claim 1, wherein: a step of forming an insulating layer on the aluminum-based lower wiring layer; a connection hole for electrically connecting the insulating layer to the aluminum-based lower wiring layer. To form a hole until it reaches the aluminum-based lower wiring layer; Ti is formed on at least the bottom of the connection hole.
A step of forming a layer by the CVD method; the aluminum-based lower wiring layer and the Ti layer are heated to react with each other to form T
A forming method comprising: a step of forming the i layer as a TiAl ₃ layer; and a step of burying an aluminum material in a connection hole to form an aluminum plug. 8. The forming method according to claim 7, wherein when the aluminum-based material is embedded in the connection hole to form the aluminum-based plug, the high-temperature sputtering method or the reflow method is used. 9. The method for forming a wiring structure according to claim 1, wherein: a step of forming an insulating layer on the aluminum-based lower wiring layer; a connection hole for electrically connecting the insulating layer to the aluminum-based lower wiring layer. To form a hole until it reaches the aluminum-based lower wiring layer; Ti is formed on at least the bottom of the connection hole.
A method of forming, comprising a step of forming an Al ₃ layer by a CVD method; and a step of burying an aluminum material in a connection hole to form an aluminum plug. 10. The forming method according to claim 9, wherein the aluminum-based material is embedded in the connection hole to form the aluminum-based plug by a high temperature sputtering method or a reflow method.