JPH07109828B2 - Method for manufacturing multilayer wiring structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multilayer metal wiring structure and a method for manufacturing the same, and in particular, gold wiring having a gold connection pillar between each layer wiring, or a tungsten film, or The present invention relates to a highly reliable multilayer fine gold wiring structure having a gold connection column and a gold wiring covered with a bolybdenum film, and a manufacturing method thereof.

[Conventional technology]

Conventionally, in the case of Al wiring as a multi-layer wiring technology having a connection pillar between each layer wiring of this kind, as shown in FIG. 5, first, as shown in FIG. Cu-containing) 502, Al film First W film (containing Ti) 503 as a barrier during etching, Al column second Al film (containing Cu) 504, Al
Second W film (containing Ti) that acts as a barrier during film etching 50
5 is continuously sputtered (FIG. 5 (a)).

Next, in order to leave only the portion that will be the Al pillar 506, the second W film (containing Ti) 505 and the second
Al film 304 is selectively removed by etching (FIG. 5 (b)). Subsequently, in order to leave a portion to be the Al wiring 507, the Al pillar 506 is selectively removed by etching the first W film (containing Ti) 503 and the first Al film 502 using a photoetching technique. The Al wiring 507 having the above is formed (FIG. 5 (c)). As shown in FIG. 5 (d), the interlayer insulating film is formed and flattened by forming a plasma chemical vapor deposition silicon oxide film 508, then forming a photoresist film 509, and forming an opening in a portion above the Al pillar ( 5 (e)), the silicon oxide film on the Al pillar is removed by etching to expose the upper portion of the Al pillar (FIG. 5 (f)). Further, there is a method of forming a multi-layer Al wiring having two or more layers by repeating the above steps (V-MIC Conf. Proc. 1986 Jure 9-10, P450 to 456).

On the other hand, Al wiring is prone to Al hillocks and has poor electromigration resistance.Therefore, in devices used at high currents such as bipolar LSI, silicon nitride produced by plasma enhanced chemical vapor deposition is used as an interlayer film. A two-layer gold-plated wiring using a two-layer structure of a film and a silicon oxide film has been studied (Solid State Technolog
y, 12,1983, P137).

[Problems to be Solved by the Invention]

However, the above-described conventional technique has the following problems with Al wiring. First, the number of steps is large and complicated, and high yield cannot be expected. Second, although the Al pillars are formed by dry etching, the controllability is poor, and it is difficult to form fine Al pillars, and it is difficult to increase the density. Further, since the plasma-enhanced chemical vapor deposition silicon oxide film used as the interlayer film has poor flatness, the resist film is used for flattening and patterning, and the silicon oxide film on the metal pillar is removed by etching. When such misalignment occurs, there is a problem in that a portion having extremely poor flatness is generated and the yield is reduced.

Further, in the above-described conventional gold-plated wiring having a two-layered interlayer film structure, the interlayer film has a two-layered structure of a silicon nitride film and a silicon oxide film formed by plasma enhanced chemical vapor deposition, so that its flatness is poor, There is a problem that a high yield cannot be obtained when miniaturized.

The object of the present invention is to solve the above problems, namely,
An object of the present invention is to provide a multilayer fine gold wiring structure having a gold-plated pillar with excellent flatness, high yield, and high reliability, and a manufacturing method thereof.

[Means for Solving the Problems]

The highly reliable multilayer fine gold wiring structure of the present invention is a gold wiring formed by a plating method, and a gold pillar or a gold wiring and a gold pillar formed by the plating method for electrically connecting between the respective layer wirings. The surface has a selectively formed tungsten film or a gold-plated wiring covered with a molybdenum film, and further an organic coating film such as a polyimide film as an interlayer insulating film, a silicon-containing polyimide film or an organic silica film, or The lower layer has an organic coating film having a silicon nitride film or a silicon oxide film formed by a plasma chemical vapor deposition method or a sputtering method.

Further, according to the method of manufacturing a highly reliable multilayer fine gold wiring structure of the present invention, after forming an insulating film on an element substrate, a titanium-containing tungsten film or a titanium film and a titanium-containing tungsten film is used as a first barrier metal. 2 step of forming a two-layer film by a sputtering method, a step of forming a gold thin film having a thickness of 500 to 1000Å by a sputtering method, a step of forming and patterning a first photoresist film, and an electrolytic plating method. A step of forming a first gold wiring, a step of curing the first photoresist film surface by reactive ion etching using a fluorine-based gas such as CF ₄ or irradiation with ultraviolet light; Then, the first gold wiring is formed on the first photoresist film to form the second photoresist film.
Patterning to form a first opening in a portion where electrical conduction is established between the first gold wiring and the second gold wiring, and subsequently, the first opening is formed in the first opening by electrolytic plating. A step of depositing gold to form a gold pillar, a step of improving the adhesion between the lower-layer gold wiring and the gold pillar by heat treatment, and subsequently, using O ₂ plasma, a first photoresist film and a first photoresist film, The step of ashing the second photoresist film at the same time and the gold thin film and the barrier metal other than the first gold wiring portion are removed by ion milling, reactive ion beam etching or the like, thereby forming a gold-plated pillar on the upper part. The step of forming the gold wiring, or the selective tungsten film or the molybdenum film is formed only on the surface of the first gold wiring having the gold-plated pillars by the chemical vapor deposition method to form a tungsten film on the surface. A step of forming a first gold wiring having a film or a molybdenum film and having a gold-plated pillar on the upper part, and subsequently forming a polyimide film, a silicon-containing polyimide film, or an organic coating film such as an organic silica film. Step, or a step of forming an organic coating film after forming a silicon nitride film or a silicon oxide film by a plasma chemical vapor deposition method or a sputtering method in the lower layer, and etching back the interlayer insulating film The step of exposing the upper part of the gold-plated pillar, the surface of the tungsten film or the surface of the molybdenum film on the upper part of the gold-plated pillar, and the step of forming the second barrier metal and the subsequent steps are repeated to obtain the second gold wiring. A step of forming
Further, there is a step of forming multi-layered gold wiring by the same step.

That is, the present invention does not remove the photoresist film, which serves as a mask for gold plating during formation of the lower layer gold wiring, after removing the photoresist film surface, by reactive ion etching using CF ₄ or by irradiating with ultraviolet light. After being cured by the above, by forming and patterning the photoresist film and the photoresist film on the gold wiring, providing an opening on the lower layer gold wiring, and performing gold plating again,
After forming a gold-plated pillar on the lower layer gold wiring and completely removing the photoresist film by O ₂ plasma treatment, the gold thin film and the barrier metal other than the gold wiring portion are removed to form a gold-plated pillar on top. Selectively tungsten film on the surface of gold wiring or gold wiring and gold-plated pillar of 1 or
A molybdenum film is formed, a polyimide resin film, a silicon-containing polyimide film, or a coating film such as an organic silica film, or a plasma chemical vapor deposition method in the lower layer, or
The coating film having a silicon nitride film or a silicon oxide film is formed by a sputtering method, and the gold plating pillar upper part or the gold plating pillar upper part or the tungsten film or the molybdenum film on the gold plating pillar upper part is formed by etching back. The surface of is exposed and a second gold wiring is formed.
Further, the multilayer fine gold wiring is formed by the same process.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a process sectional view of a method for manufacturing a two-layer gold wiring structure according to the first embodiment of the present invention.

First, as shown in FIG. 1 (a), an insulating film 102 having an opening 103 is formed on an element substrate 101, and then, FIG. 1 (b) is formed.
Titanium-containing tungsten film with a thickness of about 1500Å as shown in
104, a gold thin film 105 having a thickness of about 500 Å is formed by a sputtering method, and a photoresist film 106 having a thickness of about 1.5 μm is formed and patterned as shown in FIG. 1 (c). The photoresist film 106 is removed. Next, as shown in FIG. 1 (d), a thickness of 1 μm was formed by electrolytic plating.
m first gold-plated wiring 107 is formed. Then, under the conditions that the flow rate of CF ₄ gas is 30 SCCM, the pressure is 5 Pa, and the high frequency power is 400 W,
Reactive ion etching is performed for 0 minutes, and as shown in FIG. 1 (e), the photoresist film 106 is etched back by a thickness of about 0.5 μm, and at the same time, the photoresist film 10 is removed.
A hardened layer 108 is formed on the surface of 6. Then, FIG. 1 (f)
As shown in Figure 1, again, a photoresist film 1 with a thickness of about 1.5 μm
09 is formed and patterned, and a gold pillar 110 for electrically connecting the first and second gold wirings is formed with a height of about 1 μm by the electroplating method. Next, the first gold wiring 107 and the gold pillar 1
A heat treatment for improving the adhesiveness with 10 is performed at 200 ° C. for 30 minutes in a nitrogen gas atmosphere. Subsequently, the photoresist films 106, 108, and 109 are simultaneously ashed and removed by O ₂ plasma, and the first
The structure shown in Figure (g) is obtained. Next, as shown in FIG. 1 (h), the gold thin film 105 and the titanium-containing tungsten film 104 in the portion without the gold-plated wiring are removed by an ion milling method to form a first gold wiring having a gold pillar. To be done.

Next, on the first gold wiring having the gold pillar formed above,
As shown in FIG. 1 (i), a polyimide film 111 is formed with a thickness of about 2 μm, and CF ₄ gas flow rate is 5 SCCM, O ₂ gas flow rate is 30 SCCM,
Under the conditions of a pressure of 6 Pa and a high frequency power of 300 W, the entire surface is etched back by reactive ion etching for about 5 minutes, and the gold pillar is used.
Make the surface of 110 appear. Next, as shown in FIG. 1 (j), a titanium-containing tungsten film having a thickness of about 1500Å
112, a gold thin film 113 having a thickness of about 500Å is formed by a sputtering method, a photoresist film 114 having a thickness of about 1.5 μm is formed and patterned as shown in FIG. 1 (k), and a second gold wiring is formed. The portion of the photoresist film 114 to be removed is removed. Subsequently, a second gold wiring 115 having a thickness of about 1 μm is formed by the electroplating method, and then the photoresist film 114 is removed to obtain the structure shown in FIG. 1 (l). Then, the gold thin film 113 in the portion where the second gold wiring 115 is not formed and the titanium-containing tungsten film 112.
Are removed by an ion milling method to form a two-layer gold wiring structure as shown in FIG. 1 (m).

A gold pillar having a diameter of about 1 μm of the formed two-layer gold wiring structure;
When the electrical continuity with the first and second gold wirings was examined, the connection resistance including the wiring resistance per gold pillar was 0.1 to 0.2Ω, and the yield was 95% or more. This is practically
There was no problem.

Next, a second embodiment according to the present invention will be described. In the second embodiment, a manufacturing method in the case of using a two-layer film of a plasma chemical vapor deposition silicon nitride film and a polyimide film as an interlayer insulating film will be described.

In FIG. 2 (a), the process up to that of FIG. 1 (h) described in the first embodiment is completed, that is, the first gold-plated wiring 202 and the gold pillar having a titanium-containing tungsten film in the lower layer.
A plasma-enhanced chemical vapor deposition silicon nitride film 204 having a thickness of about 0.2 μm is formed on the element substrate 201 on which 203 is formed, and subsequently a polyimide film 205 having a thickness of about 2 μm is formed (second).
Figure (b)). Next, CF ₄ gas flow rate 5SCCM, O ₂ gas flow rate 30SCC
After etching back for about 5 minutes under the conditions of M, pressure 6Pa, high frequency power 300W, CF ₄ gas flow rate 30SCCM, pressure 5Pa, high frequency power
Plasma chemical vapor deposition silicon nitride film under the condition of 300 W
The surface of the gold pillar 203 is exposed by etching back 204 (FIG. 2 (c)). Then, a second titanium-containing tungsten film 206 having a thickness of about 1500Å and a second gold thin film 207 having a thickness of about 500Å are formed by a sputtering method by the same process as in the first embodiment (see FIG. d)), thickness about 1.5
forming and patterning a photoresist film 208 of μm,
A second gold wiring 209 having a thickness of 1.5 μm is formed by the electroplating method (FIG. 2 (e)). Next, the photoresist film 208 is removed, and the gold thin film 207 in the portion where the second gold-plated wiring 209 is not provided and the titanium-containing tungsten film 206 are sequentially removed by the ion milling method, as shown in FIG. A two-layer gold wiring structure as shown is formed.

The two-layer gold wiring structure thus formed has a connection resistance of 0.1 to 0.2 Ω including a wiring resistance per gold pole, and a yield of 95% or more, as described in the first embodiment. Yes, there was no problem in practical use.

FIG. 3 is a process cross-sectional view of a method for manufacturing a two-layer gold wiring structure in which a gold-plated pillar and a first gold wiring are covered with a tungsten film, which is a third embodiment of the present invention.

As shown in FIG. 3 (a), an insulating film 302 having an opening 303 is formed on an element substrate 301, and subsequently, as shown in FIG. 3 (b), a titanium-containing tungsten film having a thickness of about 2000 Å. 30
4, forming a gold thin film 305 with a thickness of about 500 Å by sputtering,
As shown in FIG. 3C, a first photoresist film 306 having a thickness of about 1.5 μm is formed and patterned. next,
As shown in FIG. 3D, the first gold-plated wiring 307 having a thickness of about 1 μm is formed by the electrolytic plating method. Then, reactive ion etching was performed for 20 minutes under the conditions of a CF ₄ gas flow rate of 30 SCCM, a pressure of 5 Pa, and a high frequency power of 400 W, and a photoresist film 306 was formed to a thickness of about 0.5 μm as shown in FIG. 3 (e).
At the same time, the hardened layer 308 is formed on the surface of the photoresist film 306 at the same time as it is etched back and removed. Subsequently, as shown in FIG. 3 (f), a photoresist film 309 having a thickness of about 1.5 μm is formed and patterned again, and gold for electrically connecting the first and second gold wirings is formed. The pillar 310 is formed by electrolytic plating to have a height of about 1 μm. Next, the first gold wiring
Heat treatment at 200 ℃ for improving adhesion between 307 and gold pillar 310
Perform in a nitrogen gas atmosphere for 0 minutes. Then, the photoresist films 306, 308, 309 are ashed and removed by O ₂ plasma,
The structure shown in FIG. 3 (g) is obtained.

Next, as shown in FIG. 3 (h), by removing the gold thin film 305 and the titanium-containing tungsten film 304 in the portion where the gold-plated wiring 307 is not formed by reactive ion beam etching, the gold pillar 310 having the gold pillars 310 is formed. 1 gold wiring is formed.
Next, as shown in FIG. 3 (i), a thickness of about 0.2 is selectively formed on the surfaces of the first gold wiring and the gold pillars 310 by the chemical vapor deposition method.
A tungsten film 311 having a thickness of μm is formed.

After that, as shown in FIG. 3 (j), the polyimide film 312
Is formed to a thickness of about 2 μm, and the entire surface is etched back by reactive ion etching for about 5 minutes under the conditions of CF ₄ gas flow rate 5 SCCM, O ₂ gas flow rate 30 SCCM, pressure 6 Pa, high frequency power 300 W, and the top of the gold pillar 310. The surface of the tungsten film 311 is exposed. Next, as shown in FIG. 3 (k), the thickness is about 20.
A tungsten film 313 containing titanium having a thickness of 00 Å and a gold thin film 314 having a thickness of about 500 Å are formed by a sputtering method, and a photoresist film 315 having a thickness of about 1.5 μm is formed as shown in FIG. 3 (l).
Pattern. Subsequently, a second gold wiring 316 having a thickness of about 1 μm is formed by electrolytic plating, and then the photoresist film 315 is removed to obtain the structure of FIG. 3 (m). After that, the gold thin film 314 and the titanium-containing tungsten film 313 in the portion where the second gold wiring 316 is not present are removed by reactive ion beam etching, so that the two-layer gold is formed as shown in FIG. 3 (n). A wiring structure is formed.

A gold pillar 310 with a diameter of about 1 μm of the formed two-layer gold wiring structure
Then, when the electrical continuity with the first and second gold wirings was examined,
The connection resistance (including wiring resistance) per gold pillar is 0.1 to 0.2
Ω, and the yield is 95% or more, which is a value with no problem in practical use.

Next, a fourth embodiment based on the present invention will be described. In the fourth embodiment, the surface of the gold-plated pillar and the surface of the first gold wiring are covered with the tungsten film, and the plasma chemical vapor deposition silicon nitride film and the polyimide film are used as the interlayer insulating film.
A manufacturing method using a layer film will be described.

In FIG. 4 (a), the process of FIG. 3 (h) described in the third embodiment is completed. That is, as shown in FIG. 4B, on the element substrate 401 on which the first gold-plated wiring 402 and the gold-plated pillar 403 having the titanium-containing tungsten film as the lower layer are formed.
As shown in FIG. 3, a tungsten film 404 having a thickness of about 0.2 μm is selectively formed on the surface of the first gold wiring and the gold pillar by the chemical vapor deposition method. Subsequently, a plasma chemical vapor deposition silicon nitride film 405 having a thickness of about 0.2 μm is formed, and then a polyimide film 406 having a thickness of about 2 μm is formed (FIG. 4 (c)). Next, CF ₄ gas flow rate 5SCCM, O ₂ gas flow rate 30SCC
Etch back for about 5 minutes under the conditions of M, pressure 6Pa, high frequency power 300W, and then etch back the plasma chemical vapor deposition silicon nitride film under conditions of CF ₄ gas flow rate 30SCCM, pressure 5Pa, high frequency power 300W. Thus, the surface of the tungsten film 404 above the gold pillar 403 is exposed (FIG. 4 (d)). Then, by the same process as the third embodiment,
A second titanium-containing tungsten film 407 having a thickness of about 2000Å and a second gold thin film 408 having a thickness of 500Å are formed by the sputtering method (FIG. 4 (e)). Then, a photoresist film 409 having a thickness of about 2 μm is formed and patterned, and a second gold wiring 410 having a thickness of about 1.5 μm is formed by electrolytic plating (fourth).
(F)). Next, the photoresist film 409 is removed, and the gold thin film 4 in the portion where the second gold-plated wiring 410 is not provided.
08 and the titanium-containing tungsten film 407 are sequentially removed by reactive ion beam etching to form a two-layer gold wiring structure as shown in FIG. 4 (g).

In the formed two-layer gold wiring structure, the connection resistance including the wiring resistance per gold pillar is 0.1 to 0.2Ω, and the yield is 95% or more, as described in the third embodiment. The level was practically no problem. Further, the result of the reliability test of the formed two-layer wiring structure was good, and it was found that there was no particular problem in practical use.

〔The invention's effect〕

As described above, according to the present invention, when the lower layer gold plated wiring is formed, the photoresist film surface used as the mask is
By performing reactive ion etching with a fluorine-based gas such as ₄ or by curing by irradiating with ultraviolet light, the photoresist film formed by coating at the time of forming the gold pillar and the lower photoresist film are completely mixed. In addition, the problem that the photoresist film remains in the lower part of the opening where the gold pillar is formed does not occur at all.

Further, since the photoresist film remains on the portion other than the gold wiring portion, the flatness of the surface is high and a uniform gold pillar can be formed regardless of the height of the gold wiring pattern. Therefore, the yield can be improved. Further, since it has excellent flatness, it also has an advantage that it can be easily formed into a multi-layer. In addition, the number of steps can be shortened and mass productivity is high as compared with the conventional technique.

Therefore, the present invention is very useful for manufacturing a device having a multilayer wiring structure.

[Brief description of drawings]

FIGS. 1A to 1M are process cross-sectional views showing a method for manufacturing a two-layer gold wiring structure according to the first embodiment of the present invention,
2A to 2F are process cross-sectional views showing a method for manufacturing a two-layer gold wiring structure according to the second embodiment, and FIGS. 3A to 3F.
(N) is a process sectional view showing a method for manufacturing a two-layer gold wiring structure according to a third embodiment of the present invention, and FIG. 4 (a).
5A to 5G are process cross-sectional views showing a method for manufacturing a two-layer gold wiring structure according to the fourth embodiment, and FIGS. 5A to 5F are conventional multilayer wiring structures having metal pillars. FIG. 6 is a process cross-sectional view showing the manufacturing method of FIG. 101 ... Element substrate, 102 ... Insulating film, 103 ... Opening, 104,1
12 ... Titanium-containing tungsten film, 105,113 ... Gold thin film, 106,109, 114 ... Photoresist film, 107 ... First gold-plated wiring, 108 ... Photoresist film surface hardening layer, 1
10 …… Gold pillar, 111 …… Polyimide resin film, 115 …… Second gold plated wiring, 201 …… Element substrate, 202 …… First gold plated wiring, 203 …… Gold pillar, 204 …… Plasma chemical vapor phase Growing silicon nitride film, 205 ... Polyimide film, 206 ... Second titanium-containing tungsten film, 207 ... Second gold thin film, 208 ...
… Photoresist film, 209… Second gold-plated wiring, 301
...... Element substrate, 302 …… Insulation film, 303 …… Aperture, 304,313
...... Titanium-containing tungsten film, 305,314 …… Gold thin film, 3
06,309,315 …… Photoresist film, 307 …… First gold-plated wiring, 308 …… Photoresist film surface hardening layer, 310…
… Gold pillars, 311 …… Tungsten film, 312 …… Polyimide film, 316 …… Second gold plated wiring, 401 …… Element substrate, 40
2 ... First gold-plated wiring, 403 ... Gold pillar, 404 ... Tungsten film, 405 ... Plasma chemical vapor deposition silicon nitride film, 406 ... Polyimide film, 407 ... Second titanium-containing tungsten film, 408 ... second gold thin film, 409 ... photoresist film, 410 ... second gold-plated wiring, 501 ... substrate, 502 ... first Al film, 503 ... first W film (containing Ti) ), 504 ... second Al film, 505 ... second W film (containing Ti), 506 ... Al pillar, 507 ... Al wiring, 508 ... silicon oxide film, 509 ... photoresist film.

Claims (2)

[Claims] 1. A step of forming a wiring layer having a gold thin film on a surface of an element substrate, and a first step on the wiring layer having the gold thin film.
Selectively forming a photoresist film and forming a first gold wiring on the portion of the wiring layer not covered with the first photoresist film by electrolytic plating, and the first photoresist. Curing the film surface to form a cured layer; forming a second photoresist film on the cured layer on the surface of the first gold wiring and the first photoresist film; A step of selectively forming an opening in the photoresist film to expose a part of the first gold wiring; and a step of forming a gold pillar by depositing gold in the opening part by an electrolytic plating method, A method of manufacturing a multilayer wiring structure, comprising: a step of removing the first and second photoresist films; and a step of forming an interlayer insulating film having at least an organic coating film after that. 2. The method of manufacturing a multilayer wiring structure according to claim 1, wherein the hardened layer is formed by reactive ion etching using CF ₄ gas for the first photoresist film.