JP2000150419A - Method for depositing metallic film, forming of wiring pattern, and structure thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which projecting eave sections are formed on the edges of metallic films at the time of forming the metallic films by vapor deposition, sputtering, etc., and to make a resist having no inversely tapered shape to work similarly to a resist having an inversely tapered shape by utilizing this method. SOLUTION: A resist pattern 12 having a rectangular cross section is formed on a substrate 11. Then projecting eave sections 13a are formed on the edges of Al films 13 formed on the pattern 12 by making Al particles 15 fly to the edges from an oblique direction while the substrate 11 is rotated. When the rotation of the substrate 11 is stopped and the particles 15 are made to perpendicularly enter the openings 12a of the pattern 12 thereafter, wiring patterns 14 having line widths which are narrower than the widths of the openings 12a are formed in the openings 12a, because the particles 15 are interrupted by the eave-like projecting sections 13a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of depositing a metal film, a method of forming a wiring pattern, and a structure of a wiring pattern.

[0002]

2. Description of the Related Art (First Conventional Example) As one method of forming fine wiring, a lift-off method as shown in FIGS. 1A to 1F is known. In this method, after a resist 2 is applied to the surface of a substrate 1 on which fine wiring is to be formed [FIGS. 1A and 1B], a photomask 3 is superposed on the resist 2 and irradiated with ultraviolet light. The resist 2 is exposed through the opening 3a of the photomask 3 (FIG. 1C). Next, when the resist 2 is developed with a developing solution, the resist 2 in a region not irradiated with the ultraviolet rays is dissolved and removed, and a resist pattern 4 having the same pattern as the opening 3a of the photomask 3 is obtained (FIG. 1D).

In order to ensure the removability of the resist pattern 4 after forming the metal material, it is desirable that the adhesion between the resist pattern 4 and the fine wiring 6 be as low as possible. Since the resist pattern 4 must be separated from the metal film 5 on the substrate 1 so as not to be connected, the resist pattern 4 becomes wider at this stage (the opening 4a becomes narrower at the opening end, as shown in FIG. 1D). ) Molded into a reverse taper shape. To form the resist pattern 4 into an inverse tapered shape, a negative resist or Si
A method using a contained resist, an image reverse method, or the like is used.

When the resist pattern is formed in a reverse tapered shape in this way, a metal film 5 is deposited on the resist pattern 4 and the substrate 1 by a technique having high perpendicular incidence of particles, such as vapor deposition or low-pressure remote sputtering [FIG. 1
(E)]. At this time, a metal film 5 is deposited in a predetermined pattern on the substrate 1 through the opening 4a of the resist pattern 4. However, since the resist pattern 4 has an inversely tapered shape, the metal film 5 deposited on the substrate 1 by vertical incidence. Membrane 5
Is determined by the size of the opening of the resist pattern 4, and the metal film 5 deposited in the opening 4a of the resist pattern which has become wider inside and the side surface of the resist pattern 4 do not adhere to each other, so that a gap is formed. Therefore, when this is immersed in an organic solvent and the resist is stripped, the metal film 5 on the resist pattern 4 is stripped together with the resist pattern 4 by lift-off, and the desired fine wiring 6 can be obtained on the substrate 1 with high precision. FIG.
(F)].

In the conventional lift-off method, it is necessary to form an inversely tapered resist pattern 4 in order to ensure the releasability of the resist pattern 4. For example, in order to make 4 a reverse tapered shape, in a method using a negative resist or an image reverse method,
There is a problem that the type of resist is limited, and the method using a Si-containing resist has a problem that the process is complicated. In addition, since the root of an inversely tapered resist pattern becomes narrow, there is a problem that the resist falls down in a narrow region, and it is extremely difficult to form a fine resist pattern.

On the other hand, if the shape of the resist pattern is rectangular or forward tapered, the metal film deposited on the substrate comes into close contact with the resist pattern, making it difficult to remove the resist. Further, even if the resist can be stripped, the problem that the fine wiring adheres to the resist pattern and is partially stripped during the stripping of the resist is likely to occur.

(Second Conventional Example) In an electrode of a semiconductor device, an upper electrode is formed on a lower electrode in order to reduce wiring resistance, and a lower electrode and an upper electrode are formed in order to prevent diffusion of electrode elements. In some cases, an intermediate electrode such as a diffusion barrier layer is provided between them. In such an electrode structure having three or more layers, if the thickness of the intermediate electrode is small, a bridge may be generated between the upper electrode and the lower electrode when the upper electrode is formed, and a short circuit may cause a failure.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems, and an object of the present invention is to provide a method for forming a metal film by vapor deposition or sputtering. To provide a method for forming an eaves-shaped convex portion on the surface. Another object of the present invention is to make the resist having no reverse taper shape work the same as the resist having the reverse taper shape by using the eave-shaped convex portion. Also,
The object of the present invention is to prevent occurrence of a short circuit between non-adjacent metal layers in three or more metal layers by using the eave-shaped convex portions.

[0009]

DISCLOSURE OF THE INVENTION The method for depositing a metal film according to claim 1 is characterized in that:
A method of depositing a metal film by a physical vapor deposition method such as vapor deposition or sputtering, and forming an eaves-like convex portion on the deposited metal film by changing the incident direction of flying metal particles obliquely incident on the deposition surface. It is characterized by doing.

When metal particles are incident on a deposition surface of a metal film, for example, a patterned resist or an upper surface of an already deposited metal film from an oblique direction, the metal particles are deposited on the side surface of the deposition surface or the side surface of the deposited metal film. Therefore, the metal film also grows in the lateral direction. Then, by changing the incident direction of the flying metal particles, a metal film can be grown in each direction of the deposition surface to form an eave-shaped projection.

Various methods can be considered as a method of changing the incident direction of the flying metal particles on the deposition surface. For example, as described in the second embodiment, a deposition method for depositing a metal film is described. A method of causing metal particles to fly from a direction inclined from the rotation axis while relatively rotating the deposition surface and the flying direction of the metal particles around a rotation axis perpendicular to the surface, deposition for depositing a metal film A method of relatively rotating the deposition surface and the flying direction of the metal particles around a rotation axis that is not perpendicular to the surface, and relatively oscillating the deposition surface for depositing the metal film and the flying direction of the metal. How to make
A method of changing the degree of vacuum for forming the metal film, a method of changing a distance between a film forming source for emitting metal particles and a deposition surface for depositing the metal film, and the like are considered. According to these methods, uniform convex portions can be easily formed.

According to a third aspect of the present invention, there is provided a method of forming a wiring pattern, comprising the steps of: patterning a resist applied on the surface of a substrate into a predetermined pattern; and performing physical vapor deposition such as vapor deposition or sputtering. Depositing the metal particles on the metal film formation surface by obliquely entering the flying metal particles on the metal film formation surface, and forming an eaves-like convex portion at the edge of the metal film deposited on the metal film formation surface. It is characterized by:

According to this method of forming a wiring pattern, it is possible to form an eaves-like projection on the wiring pattern in the wiring pattern or in an intermediate form of the wiring pattern by the principle of the method of depositing a metal film according to claim 1. it can. Therefore, it is possible to form a wiring pattern having a width narrower than the width of the resist pattern without using a resist pattern having a reverse tapered cross section by using the eave-shaped convex portion, or to form an eave-shaped convex portion on the side surface of the intermediate portion. It becomes possible to manufacture a wiring pattern having a dark spot.

According to a fourth aspect of the present invention, there is provided a method for forming a wiring pattern, comprising: a step of patterning a resist applied on a surface of a substrate into a predetermined pattern; Forming an eaves-like projection on the edge of the metal film deposited on the resist by obliquely incident particles, and depositing metal particles almost vertically in the resist opening by depositing metal particles in the resist opening. The method is characterized by comprising a step of depositing a film and a step of removing the resist on the substrate together with the metal film deposited on the resist.

According to this method of forming a wiring pattern, an eaves-like convex portion is formed on the metal film deposited on the resist, so that even if the cross section of the resist is not reverse-tapered, the resist and the The metal film can perform the same function as the reverse tapered resist. That is, the opening of the resist is narrowed by the eave-shaped protrusions of the metal film, and a wiring pattern smaller than the opening width of the resist is generated in the opening of the resist.

Therefore, unlike the conventional method using a reverse-tapered resist pattern, the type of resist is not limited and the manufacturing process is not complicated.
A wiring pattern with a fine line width can be obtained.

The structure of the wiring pattern according to the fifth aspect is
A wiring pattern structure in which electrode materials are stacked in a plurality of layers, wherein an edge of any one of the electrode material layers protrudes from a side surface of a lower electrode material layer and an upper electrode material layer.

The structure of the wiring pattern is obtained by applying the method of forming the eaves-shaped projections according to the first aspect, and is manufactured by, for example, the method of the third aspect. In this wiring pattern, since the edge of the central electrode material layer protrudes from the side surface in an eaves shape, the creepage distance between the upper electrode material layer and the lower electrode material layer becomes longer by that amount, and the central electrode material layer Even if it is thin, it is difficult for a bridge to be generated between the upper and lower electrode material layers, and a short circuit between layers in the wiring pattern can be prevented.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS.
(D) shows a method for forming a fine wiring pattern according to the first embodiment of the present invention. This is an embodiment of forming fine wiring by a lift-off method using a rectangular positive resist.

First, after a positive resist (PFI-26; manufactured by Sumitomo Chemical) is spin-coated on the alumina substrate 11, the resist is patterned by photolithography.
A rectangular (cross-sectional) resist pattern 12 as shown in FIG. 2A was formed. The resist pattern 12 is a line
The pattern was such that AND and space (L / S) were W1 = 0.5 μm, and the resist film thickness was set to T1 = 1 μm. Then, using this resist pattern 12, an Al film 13 having a thickness of 500 nm was formed by sputtering under the following conditions [FIGS. 2 (b) and 2 (c)].

At this time, the substrate 11 is rotated (rotated) at 90 rpm for 3 minutes from the start of the formation of the Al film 13 while the Al film is formed.
After the film 13 was deposited [FIG. 2 (b)], the rotation of the substrate 11 was stopped until the film formation was completed, and the Al film 13 was deposited [FIG. 2 (c)]. For three minutes (initial process) from the start of film formation, as shown in FIG. 3A, the substrate 11 is rotated and the incident angle α of the flying Al particles 15 with respect to the rotation axis R of the substrate 11 is increased. The wraparound of the Al film 13 is increased, and the rectangular resist pattern 1 is formed as shown in FIG.
An eave 13a of the Al film 13 is formed on the upper surface of the substrate 2. This eaves 1
Since 3a protrudes into the opening of the resist pattern 12, the resist pattern 12 and the Al film 13 having the same effect as the reverse tapered resist pattern 12 can be formed. Thereafter, the rotation of the substrate 11 is stopped and the incident angle α of the Al particles 15 is reduced (Al particles 1
When the Al film 13 is prevented from sneaking around the Al film 13, the eaves 13a of the Al film 13 shield the Al particles 15, so that the Al film 1 deposited in the opening of the resist pattern 12 is formed.
3 (fine wiring) is narrower than the opening width of the resist pattern 12, and as shown in FIG.
A gap is formed between the resist pattern 12 and the Al film 13 in the opening 2.

Thereafter, when the substrate 11 is immersed in acetone to peel off the resist pattern 12, the Al film 13 on the resist pattern 12 is peeled off together with the resist pattern 12, and a desired Al wiring is formed on the substrate 11 by lift-off. A pattern 14 (fine wiring) was obtained.

In the method of this embodiment, the substrate 11
Is rotated, the Al film 13 is deposited while changing the incident direction of the flying Al particles 15 on the wiring formation surface, and the eaves 1 of the Al film 13 are formed on the resist pattern 12.
Since the resist pattern 3a is formed, the same function as that of the resist pattern 12 having the reverse tapered shape can be provided without forming the resist pattern 12 in the reverse taper shape. Therefore, fine wiring can be formed by the lift-off method without forming the resist pattern 12 in a reverse taper shape. Therefore, as compared with the conventional method using the inversely tapered resist pattern 12, there is no limitation on the resist material, the number of options is larger than before, and the process of forming fine wiring can be simplified.

(Second Embodiment) FIG. 4 shows a method for forming a fine wiring pattern (fine wiring) according to a second embodiment of the present invention. This utilizes a technique of forming an eaves of a metal layer, and forms a multilayer multi-line fine wiring by a lift-off method using an inversely tapered resist pattern.

First, a chemically amplified negative resist (TLOR: manufactured by Tokyo Ohka) is spin-coated on a sapphire substrate 21.
An inversely tapered resist pattern 22 having a multi-line structure was formed by a reduced projection exposure method (FIG. 4A). The width W2 of the opening 22a of the resist pattern 22 is 50 μm.
The resist film thickness T2 was 4 μm.

Then, by EB (electron beam) evaporation,
From the substrate 21 side, Ti (film thickness 50 nm) → Au (film thickness 1 μm) → Ti (film thickness 30 nm) → SiO ₂ (film thickness 20
0 nm) → Al (film thickness 2 μm) was formed [FIG. 4 (b)
(C) (d)]. At this time, substrate heating and substrate rotation were not performed. Here, when the lower electrode 23 made of Ti, Au, and Ti is formed (FIG. 4B), the gas pressure is set to 2 × 1.
0 ^{-4 to} 6 × 10 ^-4 Pa, and O ₂ gas was introduced only when the intermediate electrode 24 made of SiO ₂ was formed (FIG. 4C).
Film formation is performed under a pressure of × 10 ^-1 Pa, and when forming the upper electrode 25 made of Al (FIG. 4D), the gas pressure is again increased to 2 × 10 ^{-4 to} 6 × 10 ^-4 Pa. And

If the pressure is increased only during the formation of the intermediate electrode 24 made of SiO ₂ , the Brownian motion (collision with gas particles) increases the variation in the incident angle of the particles, and as a result, the incident angle α of the particles increases. Therefore, the film is formed in such a manner that the intermediate electrode 24 has a large amount of wraparound, and the inside of the opening 22a of the resist pattern 22 and the resist pattern 22
Of the intermediate electrode 24 formed on the lower electrode 23 (Ti / Au / Ti) protrudes like an eave. And
Due to the eaves-like projections 24a formed on the upper surface of the resist pattern 22 at the edge of the intermediate electrode 24, the resist pattern 22
In the opening 22a, the width of the upper electrode 25 formed on the intermediate electrode 24 is smaller than the width of the intermediate electrode 24. As a result, the edge of the intermediate electrode is eaves between the lower electrode 23 and the upper electrode 25. A projection 24a is formed to protrude in a shape.

A lower electrode 23 made of Ti / Au / Ti,
After forming the intermediate electrode 24 made of SiO ₂ and the upper electrode 25 made of Al, the substrate 21 is immersed in acetone and lifted off to obtain a desired multilayer multi-line fine wiring pattern 26 (FIG. 4E). ].

In such a multilayer wiring, since the thickness of the intermediate electrode 24 is small, the lower electrode 23 (Ti / Au / Ti)
A short-circuit easily occurs between the upper electrode 25 and the upper electrode 25 (Al). However, in this embodiment, since the intermediate electrode 24 is formed in an eaves shape and protrudes to the periphery, the lower electrode 23 and the upper electrode 25 are formed. A short circuit due to a bridge between them can be prevented, and a multilayer electrode having high reliability and a low defect rate can be manufactured.

As a method of changing the incident direction of the flying particles or the flying direction of the deposited particles, as shown in FIG. 3, the incident direction of the flying particles 15 is changed from the direction perpendicular to the substrate 11 (the rotation axis direction). Various methods are conceivable besides a method of rotating (spinning, revolving) the substrate 11 in an inclined state, and a method of controlling a film forming vacuum degree (gas pressure in a chamber) as in the second embodiment. . For example, as shown in FIG. 5, the substrate 11 may be arranged to be inclined with respect to the rotation axis R, and the flying particles 15 may be made incident parallel to the rotation axis R of the substrate 11.

As shown in FIG. 6, the distance between the substrate and a film forming source such as an evaporation source or a target may be changed. That is, when the distance between the film formation source and the substrate 11 is increased, the incident direction of the flying particles 15a incident on the substrate 11 is substantially parallel, whereas when the distance between the film formation source and the substrate 11 is reduced, the substrate 11 Since the variation in the incident direction of the flying particles 15b incident on the surface becomes large, the eave-shaped convex portion becomes large. Further, as shown in FIG. 7, by stopping the substrate 11 and changing the position of a film forming source such as an evaporation source and a target,
The direction of the flying particles 15 may be changed to form an eave-shaped convex portion. Also, as in the case of linear wiring,
When it is sufficient that the eaves-shaped protrusions can be formed only on both side surfaces of the wiring, the substrate 11 may be swung in a seesaw shape as shown in FIG.

[Brief description of the drawings]

FIGS. 1A to 1F are schematic sectional views showing a conventional method for forming a fine wiring.

FIGS. 2A to 2D are schematic cross-sectional views illustrating a method for forming a fine wiring according to an embodiment of the present invention.

FIG. 3A is a cross-sectional view showing that Al particles are obliquely implanted, and FIG. 3B is a cross-sectional view showing a metal layer deposited on a resist pattern.

4A to 4E are schematic cross-sectional views illustrating a method for forming a fine wiring according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating another method for obliquely entering Al particles.

FIG. 6 is a cross-sectional view illustrating still another method for obliquely entering Al particles.

FIG. 7 is a cross-sectional view illustrating still another method for obliquely entering Al particles.

FIG. 8 is a cross-sectional view illustrating still another method for obliquely entering Al particles.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Alumina substrate 12 Resist pattern 13 Al film 13a Al film eave 14 Al wiring pattern 15 Al particles (flying particles) 21 Sapphire substrate 22 Reverse tapered resist pattern 23 Lower electrode 24 Intermediate electrode 25 Upper electrode

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masayuki Hasegawa 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto F-term in Murata Manufacturing Co., Ltd. 4K029 AA07 BA01 BA03 BA05 BA17 BA46 BB02 BB03 BD02 CA01 CA05 EA00 EA03 EA07 HA07 JA02 4M104 AA10 BB02 BB14 DD34 DD35 DD37 DD68 FF13 5F033 HH08 HH13 HH18 JJ13 JJ18 MM08 PP15 PP19 PP21 QQ41 RR04 SS08 SS10 SS17 XX31

Claims (5)

[Claims] 1. A method of depositing a metal film by a physical vapor deposition method such as vapor deposition or sputtering, in which an incident direction of flying metal particles obliquely incident on a deposition surface is changed to form an eaves-like shape on the deposited metal film. Forming a convex portion of the metal film. 2. The method according to claim 1, further comprising: rotating the deposition surface and the flying direction of the metal particles around a rotation axis perpendicular to the deposition surface for depositing the metal film, while rotating the deposition surface and the metal particles in a direction inclined from the rotation axis. A method of rotating the deposition surface relative to a rotation axis that is not perpendicular to the deposition surface for depositing the metal film, and a direction in which the metal particles fly, and a deposition method for depositing the metal film. A method of relatively oscillating the plane and the flying direction of the metal, a method of changing the degree of vacuum for film formation when forming the metal film, a method for depositing a film formation source for emitting metal particles and a metal film. The method for depositing a metal film according to claim 1, wherein the direction of incidence of the flying metal particles on the deposition surface is changed by at least one of the methods for changing the distance from the deposition surface. . 3. A step of patterning a resist applied on the surface of the substrate into a predetermined pattern, and obliquely entering flying metal particles on the surface of the substrate or a metal film forming surface above the substrate by physical vapor deposition such as vapor deposition or sputtering. And depositing the metal particles on the metal film forming surface by forming the metal particles, and forming an eaves-like projection on the edge of the metal film deposited on the metal film forming surface. 4. A step of patterning a resist applied on the surface of the substrate into a predetermined pattern, and a step of obliquely entering flying metal particles onto the resist by physical vapor deposition such as vapor deposition or sputtering. Forming an eaves-shaped projection on the edge of the deposited metal film; depositing a metal film in the opening of the resist by depositing metal particles substantially vertically in the opening of the resist; And removing the metal film together with the metal film deposited on the resist. 5. A wiring pattern structure in which electrode materials are stacked in a plurality of layers, wherein an edge of any one of the electrode material layers protrudes from side surfaces of a lower electrode material layer and an upper electrode material layer. A wiring pattern structure characterized by the above-mentioned.