JPH1032201A - Formation of pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming patterns, which can contrive to microscopically form the wiring pattern, through which a low current is made to flow, while the wiring pattern, through which a high current is made to flow, is formed thick. SOLUTION: A photoresist 3 is exposed and developed in such a way that the photoresist 3 of a part, which is formed with a wiring pattern 9 for high current use, is all removed and the photoresist 3 of a part, which is formed with a wiring pattern 10 for signal use, remains slightly. Then, plated metal films 8 are formed by electroplating. The slighly remaining photoresist 3 (the remaining part 12) is removed by a dry etching method and thereafter, electroplating is again applied to the removed part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a wiring pattern on a semiconductor wafer, a printed wiring board, or the like.

[0002]

2. Description of the Related Art Conventionally, in a wiring pattern formed on a semiconductor wafer or a printed wiring board, a material for forming the wiring pattern has a limitation in current density, and thus a cross-sectional area is set according to an amount of flowing current. That is, a wiring pattern having a larger amount of current than a signal wiring pattern, such as a power supply wiring pattern, is formed to have a relatively large cross-sectional area. In order to increase the cross-sectional area, when the wiring width is increased, the degree of integration is reduced. Therefore, the thickness is increased.

Here, a conventional method for forming a wiring pattern will be described with reference to FIG. 4A and 4B are cross-sectional views for explaining a conventional pattern forming method. FIG. 4A shows a state in an exposure step, FIG. 4B shows a state after development, and FIG. FIG. 3D shows a state after the electroplating step is completed, and FIG. 4D shows a state after the resist is removed.

In these figures, reference numeral 1 denotes a substrate such as a semiconductor wafer or a main body of a printed wiring board, 2 denotes a barrier metal made of a conductor formed on the substrate 1, and 3 denotes a barrier metal formed on the barrier metal 2. 3 shows an applied positive photoresist. Reference numeral 4 denotes a photolithography mask.

The mask 4 is made of a transparent reticle glass 5
The opaque chromium layer 6 is provided so that the mask pattern formed of the light transmitting portion has the same shape as the wiring pattern. The mask pattern includes a large current amount mask pattern 4a for forming a large current wiring pattern having a relatively large amount of current and a signal mask pattern for forming a signal wiring pattern having a relatively small amount of current. 4b.

To form a wiring pattern on the substrate 1, first, a barrier metal 2 is formed on the substrate 1, and a photoresist 3 is applied on the barrier metal 2.
The photoresist 3 is formed to have a thickness of about 2 μm so that a relatively thick large current wiring pattern can be formed. Then, as shown in FIG. 4A, the mask 4 is opposed to the substrate 1 on which the photoresist 3 has been applied, and the photoresist 3 is exposed over the entire area in the thickness direction. The photosensitive portion is indicated by reference numeral 7 in FIG.

Next, as shown in FIG. 4B, the photoresist 3 is developed to remove the photosensitive portion 7, thereby exposing the barrier metal 2 at a portion where a wiring pattern is to be formed. Then, as shown in FIG. 4C, electroplating is performed on the substrate 1 using the barrier metal 2 as a conductive path. When electroplating is performed, plating metal 8 is formed on the exposed portion.

After the plating step is completed, the photoresist 3 is removed to expose the barrier metal 2 on which the plating metal 8 is not formed, and as shown in FIG. The exposed portion of the metal 2 is removed by etching. By performing the etching as described above, a wiring pattern is formed by the plating metal 8. That is, the plating metal 8 formed in the portion corresponding to the large current mask pattern 4a constitutes the large current wiring pattern 9, and the plating metal 8 formed in the portion corresponding to the signal mask pattern 4b corresponds to the signal. The wiring pattern 10 is formed. These wiring patterns 9 and 10 are formed so as to have the same thickness.

[0009]

However, when the wiring pattern is formed by the above-described method, the wiring width and the wiring interval of the signal wiring pattern 10 that requires a small amount of current cannot be reduced, and the pattern cannot be miniaturized. There was a problem. This is because the thickness of the photoresist 3 is determined so that the thickest large current wiring pattern 9 among the wiring patterns can be formed.
It is considered that the reason is that the thickness of the photoresist 3 in the portion where the photomask is formed is unnecessarily thick.

That is, in order to expose the photoresist 3 over the entire area in the thickness direction, the area of the light incident surface must be increased as the thickness increases, so that the wiring width and spacing of the signal wiring pattern 10 are reduced. This is because there is a limit to narrowing.

As shown in FIG. 5, the photoresist 3 is formed thin so that the signal wiring pattern 10 can be miniaturized, and a thick large-current wiring pattern 9 is formed using the photoresist 3. Signal wiring pattern 10
Since the plating metal 8 spreads along the surface of the photoresist 3, the plating metals 8 having a narrow wiring interval come into contact with each other. This contact portion is indicated by reference numeral 8a in FIG. FIG. 5 is a cross-sectional view showing a state after the electroplating step when a thin photoresist is formed. In FIG. 5, the same or equivalent members as those described in FIG. Is omitted. The photoresist 3 shown in FIG. 5 is formed relatively thin so as to have a thickness of about 1 μm.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a pattern forming method capable of miniaturizing a wiring pattern having a small amount of current while forming a wiring pattern having a large flowing current thickly. The purpose is to provide.

[0013]

According to a first aspect of the present invention, there is provided a pattern forming method, wherein the photoresist at a portion where a thick wiring pattern is formed is completely removed and the photoresist at a portion where another wiring pattern is formed slightly remains. Then, the photoresist is exposed and developed, a metal layer is formed by electroplating, the slightly remaining photoresist is removed by dry etching, and electroplating is performed again. According to the present invention, even if a photoresist is formed with a thickness capable of forming a thick wiring pattern, a portion where another wiring pattern is formed in the photoresist does not have to be exposed over the entire area in the thickness direction, so that light is incident. The area of the surface to be formed can be relatively reduced.

A pattern forming method according to a second aspect of the present invention is the pattern forming method according to the first aspect of the present invention, wherein a positive type photoresist is used, and an exposure step is performed on a portion corresponding to all wiring patterns in the photoresist. Is exposed halfway in the thickness direction, and then only the portion corresponding to the thick wiring pattern in the photoresist is exposed over the entire region in the thickness direction. The pattern forming method of the present invention can be carried out using a photolithography mask in which all wiring patterns are drawn as mask patterns, and a photolithography mask in which only thick wiring patterns are drawn as mask patterns. Since the mask pattern of these masks can be constituted only by the light-transmitting portions and the non-light-transmitting portions, the present invention can be implemented using a mask having a simple configuration.

The pattern forming method according to a third aspect of the present invention is the pattern forming method according to the first aspect of the present invention, wherein a positive type photoresist is used, and an exposure step is performed. A mask having a structure in which light is transmitted and a portion corresponding to another wiring pattern has a small amount of light transmission is used, and all portions of the photoresist corresponding to the thick wiring pattern are exposed. According to the present invention, one mask may be used in the exposure step.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment Hereinafter, an embodiment of a pattern forming method according to the first invention and the second invention will be described in detail with reference to FIGS. FIG. 1 is a cross-sectional view for explaining a pattern forming method according to the first and second inventions. FIG. 1A shows a state in a first exposure step, and FIG. 1B shows a state in a second exposure step. (C) shows the state after the first electroplating step is completed, (d) shows the state after dry etching is completed, and (e) shows the state in the exposure step. FIG. 11F shows a state after the second electroplating step is completed, and FIG. 10F shows a state after the resist is removed. FIG. 2 is a graph showing the relationship between the exposure amount and the thickness of the photoresist remaining after development. In these drawings, the same or equivalent members as those described in FIG. 4 are denoted by the same reference numerals, and detailed description is omitted.

In order to carry out the pattern forming method according to the first and second aspects of the present invention, two types of photolithography masks are used. That is, the mask 4 shown in FIG.
And the mask 11 shown in FIG. This mask 1
Reference numeral 1 denotes a reticle glass 5 and a chromium layer 6 similar to the mask 4, and only a large-current wiring pattern 9 is drawn as a mask pattern. This mask pattern is indicated by reference numeral 11a. The substrate 1 is a semiconductor wafer in this embodiment.

In order to form a wiring pattern on the substrate 1 by the pattern forming method of the present invention, first, the barrier metal 2
Then, a positive photoresist 3 is applied on the barrier metal 2 so as to have a thickness of about 1 μm. Then, as shown in FIG. 1A, a portion corresponding to all the wiring patterns in the photoresist 3 is exposed using the mask 4. The exposure amount at this time is set so that the photoresist 3 is exposed halfway in the thickness direction. In this embodiment, the setting is made so that the photosensitive portion 7 is formed only about 0.9 μm in the thickness direction from the exposed surface of the photoresist 3. That is, the photosensitive member is exposed with an exposure amount indicated by a reference symbol A in FIG.

Next, as shown in FIG.
1 is used again to expose only the portion of the photoresist 3 corresponding to the large current wiring pattern 9. The exposure amount at this time is set to an exposure amount indicated by BA in FIG. 2, that is, an exposure amount such that the photoresist 3 is exposed over the entire region in the thickness direction and the photosensitive portion 7 reaches the contact surface with the barrier metal 2. I do.

After the exposure as described above, the photoresist 3 is developed. By the development, the photoresist 3 in the portion corresponding to the large-current wiring pattern 9 is entirely removed, and the photoresist 3 in the portion corresponding to the signal wiring pattern 10 is removed by about 0.1 μm after the photosensitive portion 7 is removed. (See FIG. 2). This remaining part is shown in FIG.
Reference numeral 12 denotes the inside.

After development, the substrate 1 is subjected to electroplating using the barrier metal 2 as a conductive path. In this embodiment, a cyan plating solution is used during electroplating. When the electroplating is performed, as shown in FIG. 1C, the entirety of the photoresist 3 is removed, and a plating metal 8 is formed in a portion where the barrier metal 2 is exposed. Since a portion corresponding to the signal wiring pattern 10 is insulated by the photoresist 3 in a thin film state, no plating metal is formed. In this embodiment, the plating metal 8 is formed to have a thickness of 0.5 μm by adjusting the plating time. Note that this film thickness is a value obtained by subtracting the film thickness of the signal wiring pattern 10 from the value finally required for the large current wiring pattern 9.

Thereafter, the substrate 1 is supplied to a dry etching apparatus (not shown), and the photoresist 3 is subjected to dry etching using oxygen plasma. When oxygen plasma is used, the photoresist 3 is selectively removed and the metal portion is not removed. Therefore, when this dry etching is performed, the remaining portion 12 is removed as shown in FIG.

Next, the substrate 1 is again subjected to electroplating, and a plating metal 8 is formed on the metal portion exposed on the surface of the substrate 1 as shown in FIG. When the electroplating is performed in this manner, the thickness of the plating metal 8 formed in the first electroplating step increases, and the plating metal 8 is formed in a portion corresponding to the signal wiring pattern 10. This second electroplating step is performed by plating metal 8
Is formed so as to form about 1 μm. That is, the thickness of the plating metal 8 forming the large current wiring pattern 9 reaches about 1.5 μm, and the thickness of the plating metal 8 forming the signal wiring pattern 10 becomes about 1 μm.

Since the thickness of the photoresist 3 is about 1 μm, the plating metal 8 of the large current wiring pattern 9 extends upward from the photoresist 3 in FIG. However, the large-current wiring pattern 9 is different from the signal wiring pattern 10.
Since the wiring intervals are wider than those in the above, the plated metals 8 do not come into contact with each other.

After completion of the second electroplating step, as shown in FIG. 1 (f), by removing the photoresist 3, the thickness of the large current wiring pattern 9 differs from that of the signal wiring pattern 10. A wiring pattern can be formed.

Therefore, even if the photoresist 3 is formed with a thickness capable of forming the large current wiring pattern 9 (thick wiring pattern), the portion of the photoresist 3 where the signal wiring pattern 10 (other wiring pattern) is formed. Since it is not necessary to expose the entire surface in the thickness direction, the area of the surface on which light is incident can be relatively reduced. Therefore, the wiring width and the wiring interval of the signal wiring pattern 10 can be reduced.

The photolithography is performed using a mask 4 in which all wiring patterns are drawn as mask patterns 4a and a mask 11 in which only high-current wiring patterns are drawn as mask patterns 11a. Can be. Since the mask patterns 4a and 11a of the masks 4 and 11 can be constituted only by the light-transmitting portions and the non-light-transmitting portions, this pattern forming method can be carried out using a mask having a simple configuration.

Further, since the electroplating is performed twice and the plating metal 8 of the signal wiring pattern 10 is formed in the second electroplating step, the thickness of the large current wiring pattern 9 is reduced in the first electroplating step. The signal wiring pattern 10 by changing the thickness of the plating metal 8 formed by
Can be set irrespective of the thickness.

Second Embodiment A pattern forming method according to a third invention will be described in detail with reference to FIG. 3A and 3B are cross-sectional views for explaining a pattern forming method according to the third invention. FIG. 3A shows a state in an exposure step, and FIG. 3B shows a state after an electroplating step is completed. (C) shows the state after the dry etching is completed, (d) shows the state after the second electroplating step is completed, and (e) shows the state after the resist is removed. Is shown. In these drawings, the same or equivalent members as those described in FIG. 1 and FIG. 4 are denoted by the same reference numerals, and detailed description is omitted.

In order to carry out the pattern forming method according to the third invention, a photolithography mask indicated by reference numeral 21 in FIG. 3A is used. The mask 21 is composed of the reticle glass 5 and the chromium layer 6 and has a large current mask pattern 21 a having the same shape as the large current wiring pattern 9.
And a signal mask pattern 21b having the same shape as the signal wiring pattern 10.

The large current mask pattern 21a is configured to transmit the entire amount of light incident thereon, and the signal mask pattern 21b is configured so that the amount of transmitted light is smaller than that of the large current mask pattern 21a. Make up. Such a reduction in the amount of transmitted light is realized by partially thinning the chrome layer 6 formed on the reticle glass 5.

In order to form a wiring pattern using this mask 21, an exposure amount is set so that the photoresist 3 is exposed over the entire area in the thickness direction by light transmitted through the large current mask pattern 21a. When exposure is performed with this exposure amount, as shown in FIG. 3A, the portion of the photoresist 3 corresponding to the large current mask pattern 21a is exposed over the entire area in the thickness direction, and corresponds to the signal mask pattern 21b. The portion is exposed partway in the thickness direction due to weak incident light, and an unexposed portion remains on the barrier metal 2 side.

After the exposure step is completed, the photoresist 3
Is developed, the photoresist 3 corresponding to the high-current wiring pattern 9 is removed, and the signal wiring pattern 1 is removed.
The photoresist 3 in the portion corresponding to 0 remains as a thin film as indicated by reference numeral 12 in FIG. When the first electroplating is performed on the substrate 1 in this state, a plating metal 8 is formed at a portion corresponding to the large-current wiring pattern 9 as shown in FIG.

After the first electroplating, the remaining portion 12 is removed by dry etching as in the case of the first embodiment {see FIG. 3 (c)}. 3D, a second electroplating is performed, and as shown in FIG.
By removing the wiring pattern, it is possible to form a wiring pattern having a different thickness between the large current wiring pattern 9 and the signal wiring pattern 10.

Therefore, according to this pattern forming method, it is possible to form wiring patterns having different thicknesses (wiring pattern 9 for large current and wiring pattern 10 for signal) with one mask 21.

[0036]

As described above, in the pattern forming method according to the first aspect of the present invention, the photoresist at the portion where a thick wiring pattern is formed is entirely removed and the photoresist at the portion where another wiring pattern is formed is slightly removed. The photoresist is exposed and developed so as to remain, then a metal layer is formed by electroplating, and after removing the slightly remaining photoresist by dry etching, electroplating is performed again. Even if a photoresist is formed with a thickness that can be formed, the portion of the photoresist where another wiring pattern is formed does not have to be exposed over the entire area in the thickness direction, so that the area of the light incident surface is relatively narrowed. be able to. Therefore, it is possible to reduce the wiring width and the wiring interval of the wiring pattern having a small amount of current, while forming the wiring pattern having a large amount of flowing current to be thick, thereby achieving miniaturization.

A pattern forming method according to a second aspect of the present invention is the pattern forming method according to the first aspect of the present invention, wherein a positive type photoresist is used, and an exposure step is performed on a portion corresponding to all wiring patterns in the photoresist. After exposure to a part of the thickness direction in the thickness direction, only the portion corresponding to the thick wiring pattern in the photoresist is exposed to the entire area in the thickness direction, so that all the wiring patterns are drawn as a mask pattern as a photolithography mask. And a pattern in which only a thick wiring pattern is drawn as a mask pattern.

Since the mask pattern of these masks can be composed of only light-transmitting portions and non-light-transmitting portions, the pattern forming method of the present invention can be carried out using a mask having a simple configuration. Therefore, it is possible to minimize an increase in cost in carrying out the present invention.

The pattern forming method according to a third aspect of the present invention is the pattern forming method according to the first aspect of the present invention, wherein a positive type photoresist is used, and an exposure step is performed. Since a mask having a structure that transmits light and a portion corresponding to another wiring pattern and transmits a small amount of light is used and all portions corresponding to a thick wiring pattern in the photoresist are exposed to light, only one mask is used in the exposure process. One. Therefore, it is possible to minimize an increase in cost in carrying out the present invention.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a pattern forming method according to first and second inventions.

FIG. 2 is a graph showing a relationship between an exposure amount and a thickness of a photoresist remaining after development.

FIG. 3 is a cross-sectional view for explaining a pattern forming method according to a third invention.

FIG. 4 is a cross-sectional view for explaining a conventional pattern forming method.

FIG. 5 is a cross-sectional view showing a state after completion of an electroplating step when a thin photoresist is formed.

[Explanation of symbols]

1 ... substrate, 2 ... barrier metal, 3 ... photoresist,
4, 11, 21 ... mask, 8 ... plated metal, 9 ... wiring pattern for large current, 10 ... wiring pattern for signal, 12 ...
Remaining part.

Claims (3)

[Claims] 1. A pattern forming method for forming a part of a wiring pattern thicker than another part, comprising forming a conductor layer and a photoresist layer on a pattern forming surface, and then forming the thick wiring pattern. Exposure and development so that the conductor layer of the conductive layer is exposed and the portion of the photoresist layer where another wiring pattern is formed is thinner than the photoresist layer outside the pattern, and electroplating is performed on the exposed portion of the conductor layer to form a metal layer. Forming a pattern, the relatively thin photoresist layer is removed by a dry etching method to expose the conductor layer in this portion, and the conductor layer and the metal layer are subjected to electroplating. . 2. A pattern forming method according to claim 1, wherein a positive type photoresist is used, and an exposure step is performed after exposing portions of the photoresist corresponding to all wiring patterns to a halfway in a thickness direction. A pattern forming method in which only a portion corresponding to a thick wiring pattern in a photoresist is exposed over the entire region in the thickness direction. 3. The pattern forming method according to claim 1, wherein a positive photoresist is used as the photoresist, and the exposure step is performed in such a manner that a portion corresponding to the thick wiring pattern transmits the entire amount of light and corresponds to another wiring pattern. A pattern forming method, wherein a portion corresponding to a thick wiring pattern in a photoresist is exposed over the entire region in the thickness direction using a mask having a structure in which a portion to be transmitted has a relatively small light transmission amount.