JPS63119547A - Formation of wiring structure - Google Patents

Abstract

PURPOSE:To omit a step for removing an attached layer, which is formed on the side surface of a mask layer, by forming a second mask layer having a pattern, which is slightly smaller than that of a first mask layer with respect to at least the side of the surface, from the first mask material layer. CONSTITUTION:An Al layer 2 is formed on a substrate 1 having the insulating surface. Then a first mask material layer 11 is formed on the Al layer. Thereafter, a first mask layer 4 having a desired pattern is formed on the first mask material layer 11. Then, a second mask layer 12 having a pattern slightly smaller than that of the first mask layer 4 with respect to at least the surface side is formed. Then, with the first and second mask layers 4 and 12 as masks with respect to the Al layer 2, a patterned Al layer 5 is formed from the Al layer 2 as a wiring layer by dry etching. Even if an attached layer 6 composed of an Al oxide is formed on the side surface of the first mask layer, a removing step is not required.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a wiring structure having a patterned AI structure as a semiconductor layer.

2. Description of the Related Art Conventionally, a method for forming a wiring structure as described below with reference to FIG. 3 has been proposed.

That is, a substrate 1 having an insulating surface is prepared in advance (
(See Figure 3).

Then, on the substrate 1, an Al layer 2 is formed (third
Figure B).

Next, All! ! A mask material layer 3 made of, for example, photoresist is formed on the mask 12 (FIG. 3C).

Next, a mask 1i! having a desired pattern is formed from the mask material layer 3 by photolithography. 4 (Figure 3D).

Next, a patterned Al layer 5 is formed from the Al layer 2 as a wiring layer by dry etching the Al layer 2 using the mask WJ4 (FIG. 3E).

In this case, the side surface of the mask layer 4 is coated with aluminum produced by oxides formed on the surface of the Al layer 2, residual moisture in the reaction chamber used for the dry etching process, etc.
An unnecessary M layer 6 made of a chemical compound is formed.

Next, the mask layer 4 is removed from the patterned Al 115 by plasma etching using oxygen, wet etching, or the like (FIG. 3F). In this case, the attachment 6 attached to the side surface of the mask layer 4 remains on the patterned Alff 5.

Next, stick! ! Patterned All
! Attach it from above i5! 6 (Figure 3G).

The above is a conventionally proposed method for forming a wiring structure.

According to such a conventional wiring structure formation method, the patterned Al layer 5 as a wiring layer is formed from Alff2 by dry etching using the mask layer 4, so that the patterned Alff15 can be easily formed into a fine, desired pattern, compared to the case where it is formed by wet etching treatment accompanied by diode etching.

However, in the case of the method of forming the wiring structure described above in FIG. 3, the patterning All! In addition to the step of removing the mask layer 4, a step of removing the adhesion 116 formed on the side surface of the mask layer 4 in the step of forming the I is required.

Further, the adhesion layer 6 formed on the side surface of the mask ff14 is
Since it is made of Allide, it is chemically stable. Therefore, it is difficult to remove it by wet etching or plasma etching, and if it is removed by using external force. However, the patterned Al layer 5 may be damaged.

SUMMARY OF THE INVENTION Accordingly, the present invention seeks to propose a novel method for forming wiring structures that does not have the above-mentioned drawbacks.

In the method for forming a wiring structure according to the present invention, a desired wiring structure is formed by performing the following sequential steps.

That is, an Al layer is formed on a substrate having an insulating surface.

Next, Si oxide, Si nitride, Si
Alternatively, a first master layer made of a high melting point metal is formed.

Next, a first mask layer having a desired pattern is formed on the first mask material layer.

Next, by etching the first mask material layer using the first mask layer as a mask, the first mask material layer is etched.
From the mask material layer, a second mask layer is formed, at least on the surface side having a pattern one size smaller than that of the first mask layer.

Next, a patterned Al layer is formed from the Al layer as a wiring layer by dry etching the Al layer using the first and second mask layers as masks.

Next, the first mask layer is removed from above the second mask layer by etching the mask layer m1.

The above is the method for forming a wiring structure according to the present invention.

According to the method for forming a wiring structure according to the present invention,
Similar to the conventional wiring structure formation method described above in FIG. 3, the patterned Al layer is formed by dry etching using the first and second mask layers as masks. , similar to the conventional wiring structure formation method described above in FIG. 3, the patterned Al layer is
Compared to the case of forming by wet etching treatment accompanied by side etching, it is possible to easily form a fine and desired pattern.

However, in the method for forming a wiring structure according to the present invention, in the step of forming a patterned AIB by dry etching using the first and second mask layers as masks, the second mask layer is formed at least on the surface thereof. The pattern on the side J3 is one size smaller than that of the first mask layer, and because of this, the lower surface of the first mask layer is not in contact with the second mask layer at its outer periphery. An adhesion layer made of Al oxide is formed on the side surface of the first mask layer, as in the case of the conventional wiring structure formation method described above in FIG. Al
1o! An adhesion layer consisting of a chemical compound is hardly formed, or even if it is formed, it is formed only to a very thin thickness.

For this reason, in the process of removing the first mask layer by etching, the first mask layer is etched from the outer circumferential portion of the lower surface that is not in contact with the second mask layer, and the second mask layer is etched. removed from above the layer,
At the same time, the adhesion layer formed on the side surface of the first mask layer is removed.

Therefore, according to the method of forming a wiring structure according to the present invention, A
Patterned AI from the L layer by dry etching process
T! 1, even if an adhesion layer made of Al oxide is formed on the side surface of the first mask layer, the attached ME
No step of removing I is required in addition to the step of removing the first mask layer.

Note that in the step of removing the first mask layer, the second mask layer remains on the patterned Alff1;
The mask layer, whether made of 81 oxide, Si nitride, Si or a refractory metal, is etched, if necessary, from above the patterned AIJID by the same etching process as when forming the second mask layer. , can be easily removed.

Next, a first embodiment of the method for forming a wiring structure according to the present invention will be described with reference to FIGS. 1A to 1G.

In FIG. 1, parts corresponding to those in FIG. 3 are designated by the same reference numerals and detailed explanations are omitted.

The method for forming a wiring structure according to the present invention shown in FIG. 1 takes the following sequential steps to form a desired wiring structure.

First, as in the case of the conventional wiring structure formation method described above in FIG. 3, a substrate 1 having an insulating surface is prepared in advance (see FIG. 1).

Then, an Al layer 2 is formed on the substrate 1 (FIG. 1B) in the same manner as in the conventional wiring structure formation method described above with reference to FIG.

Next, SiF! compound, Si nitride, Si
Alternatively, the first mask material layer 11 made of a high melting point metal is formed by various methods known per se, and then the conventional wiring described above in FIG. 3 is formed on the first mask material layer 11. A mask material layer 3 similar to that described above in the structure formation method is formed as a second mask 44 layer (FIG. 1C).

Next, from the second mask material Fm3, by the same method as the conventional wiring structure formation method described above in FIG.
A mask layer 4 similar to that in the conventional wiring structure forming method described above with reference to FIG. 3 is formed as a first mask layer (FIG. 1D).

Next, the second mask layer 12 is formed from the first mask layer 11 by etching the first mask layer 11 using the first mask layer 4 as a mask (first
Figure E).

In this case, the first mask material layer 11 is Sil! In the case of a dioxide, for example, by wet etching using an etchant containing fluorine ions, and in the case of Si nitride or Si, for example, by plasma etching using a mixed gas of CH and 02. In the case of a melting point metal, the second mask layer 12 is formed by plasma etching using SF6, for example, so that at least the surface side thereof has a pattern one size smaller than that of the first mask layer 4. the bottom surface of
It is formed so that its outer peripheral portion is not in contact with the second mask layer 12. In addition, in Fig. 1, the first
The mask material WJ11 is Si oxide or S;
Since the second mask layer 12 is made of i-nitride, it has inclined side surfaces and is therefore formed in a so-called mesa shape. However, the first mask layer 11 is made of high melting point metal. In the case of ash, the second mask layer is formed with vertical sides.

Next, in accordance with the conventional method for forming the wiring M4 structure described above in FIG. From A 1112 by dry etching process,
The patterned Al layer 5 is arranged! Form as a layer (first
Figure F).

In this case, on the side surface of the first mask layer 4, an Al
An unnecessary adhesion layer 6 made of a chemical compound is formed on the outer periphery of the lower surface of the first mask layer 4 that is not in contact with the second mask layer, and at least on the side surface of the second mask layer 12. In this case, hardly any Allide is formed, or even if it is formed, it is formed only to a thin thickness.

Next, by etching the first mask layer 4 such as a plasma etching process using 02 or a wet etching process, the first mask layer 4 is etched by etching the outer periphery of the first mask layer 4 on the lower surface thereof which is not in contact with the second mask layer 12. The etching mechanism is used to remove the etching from above the mask layer 12, and at the same time, the Ti layer 6 formed on the side surface of the first mask layer 4 is removed (FIG. 1G).

The above is the first embodiment of the method for forming a wiring structure according to the present invention.

According to the method for forming a wiring structure according to the present invention,
Similar to the conventional wiring structure formation method described above in FIG. 3, the patterned Al layer 5 is formed by dry etching using the first and second mask layers 4 and 12 as masks. Therefore, as in the case of the conventional wiring structure formation method described above in FIG. Can be easily formed into patterns.

However, in the method of forming the wiring structure according to the present invention shown in FIG. 1, in the step of forming the patterned Al layer 5 by dry etching using the first and second mask layers 4 and 12 as masks, Since the second mask layer 12 has a pattern one size smaller than that of the first mask layer 4 at least on its surface side,
The side surface of the mask layer 4 has the conventional arrangement described above in FIG.
Similar to the method for forming the lAM4 structure, the adhesion layer 6 made of Al oxide is formed, but the second mask Jl! on the lower surface of the first mask ff4! At least on the surface side of the outer periphery that is not in contact with the second mask ff12 and the side surface of the second mask ff12, an adhesion layer made of Al oxide is hardly formed, or even if it is formed, it is only to a very thin thickness. Not formed.

Therefore, in the process of removing the first mask layer 4 by etching, the first mask WJ4 is etched from the outer circumferential portion of the lower surface that is not in contact with the second mask w112. Mask layer 12
At the same time, the attached WJFJ 6 formed on the side surface of the first mask layer 4 is removed.

Therefore, in the process of forming the patterned Al layer 5 from Al1li2 by dry etching, the first
Even if an adhesion layer 6 made of Al oxide is formed on the side surface of the mask layer 4, the step of removing the adhesion layer 6 is not necessary in addition to the step of removing the first mask m4.

Note that in the above description, in the step of removing the first mask layer 4, there is no mention of removing the second mask layer 12 remaining on the patterned AIJIWl.
The second mask layer 12 is composed of pentaillide, S
Since it is made of i-nitride, St, or a high-melting point metal, it can be easily removed from the patterned Alff 15 by the same etching process used to form the second mask layer, if necessary.

Embodiment 2 Next, a second embodiment of the method for forming a wiring structure according to the present invention will be described with reference to FIGS. 2A-H.

In FIG. 2, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

The method for forming a wiring structure according to the present invention shown in FIG. 2 takes the following sequential steps to form a desired wiring structure.

That is, as in the case of the present invention described above with reference to FIG. 1, a substrate 1 having an insulating surface is prepared (FIG. 2A). However, this substrate 1 has a step on its insulating surface.

Then, on the substrate 1, as in the case of the present invention described above with reference to FIG. 12 (Figure 2B).

Next, on the AI layer 2, a first mask material W111 similar to that of the present invention described above in FIG. 1 is applied, the surface of which is AIF! Next, the mask material Ii! 11, a second masking material layer 3' is formed (FIG. 2C) according to the case of the present invention described above in FIG.

In this case, the second mask material layer 3' is replaced by the first mask material layer 1.
A mask material ff13 formed on f11 with, for example, photoresist to a thickness thick enough to flatten the surface.
A, a mask material G3B formed on the mask material layer 3A to a relatively thin thickness using, for example, Si resin, and a mask material 113G formed on the mask material ff13B to a relatively thin thickness using, for example, a photoresist. It is formed as a thing consisting of.

Next, the mask material 1 constituting the second mask material layer 3'
13c, a mask layer 4C having a desired pattern is formed by a lithography method, and then a mask material layer 3B is formed.
A mask layer 4B is formed from the mask material layer by etching using the mask m4G as a mask (
Figure 2D).

Next, the second mask material It! A mask material layer 4Δ is formed from the mask material layer 3A by etching the mask material layer 3A constituting the mask material layer 53' using the mask layers 4C and 4B as masks.

In this case, if the mask 1I4c is made of a material that is substantially etched by the etching process of the mask material layer 3A, the mask material layer 3A has a large thickness, so that the mask layer 4C is a mask layer as shown in the figure. 4B (hereinafter, for simplicity, the explanation will be given assuming that the mask layer 4C has been removed in this way), and therefore, in reality, only the mask layer 4B acts as a mask for the mask material 13A, and the mask layer 4B acts as a mask for the mask material 13A. 1lJ4A is formed, thus forming a first mask WJ4' corresponding to the first mask layer 4 in the case of the invention described above in FIG. 1, consisting of masks 1i14A and 4B.

Further, since the mask material Fm 3 A has a step on the surface of the mask material 111, it has thickness unevenness, so the mask ff14A is formed by over-etching in consideration of the thickness unevenness.

As a result, an adhesion layer 13 made of the material of the mask material layer 11 is formed on the side surface of the mask ff4A' made up of the masks Jff14A and 4B.

Next, in accordance with the case of the present invention described above with reference to FIG. A second mask [212 is formed.

In this case, when the first mask material layer 11 is made of Si oxide, a first etching process is performed using, for example, a wet etching process using an etchant containing fluorine ions, and then a first etching process is performed using, for example, CF 3 and H or 02. By performing a second etching process using a reactive ion etching process using a mixed gas, the second mask layer 12 is formed so that the surface side is one size smaller than that of the first mask layer 4', as shown in the figure. It is formed to have a pattern and sloped side surfaces, but portions other than the surface side have vertical side surfaces. In addition, when the first mask material layer 11 is made of 81 nitride, the second mask layer 12 is etched through the entire thickness of the first mask by plasma etching using a mixed gas of CH and 02, for example. B4' is formed with a pattern that is one size smaller than B4' and has an inclined side surface, or a first etching process is performed using, for example, a plasma etching process using a mixed gas of CF and 02, followed by a first etching process. Then, by performing a second etching process, for example, a reactive ion etching process using a mixed gas of CF 2 and H 2 , the second mask l! 112 is formed in the same manner as when the first mask material layer 11 is made of Si oxide and as shown. Furthermore, when the first mask material Fm11 is made of Si, for example, plasma etching using a mixed gas of CF4 and 02! l! By X-embedding, the second mask layer 12 is formed to have a pattern that is one size smaller than that of the first mask layer 4' throughout its entire thickness and has an inclined side surface, or, for example, by CF
A first etching process is performed by plasma etching using a mixed gas of C1 and C02, and then, for example, C1
The second mask layer 1 is etched by performing a second etching process by reactive plasma etching using 2
2 is formed in the same manner as in the case where the first mask material layer 11 is made of SiM compound and as shown in the figure. In addition, when the first mask material layer 11 is made of a high melting point metal, the second mask layer 1 may be etched by plasma etching using SF, for example.
2 is formed so as to have a pattern that is one size smaller than that of the first mask layer 4' throughout its entire thickness, and to have vertical side surfaces. Therefore, the first mask material IFi11 is
SiP! The second mask Ji! 12, as in the case of the present invention described above with reference to FIG. is formed so that its outer periphery is not in contact with the second mask layer 12.

Further, the mask 1iW4B of the first mask layer 4' is
The mask Jit34B is removed from above the mask WiJA as shown in the figure. (described as being removed).

Next, as in the case of the present invention described above in FIG.
2, a patterned Al layer 5 is formed as a wiring layer from the Al layer 2 by dry etching using, for example, CCl2 using the first and second masks F14' and 12 as masks (see FIG. G).

In this case, an unnecessary adhesion layer 6 made of Al oxide is formed on the side surface of the first mask layer 4, as in the case of the present invention described above with reference to FIG. Almost no Al oxide is formed, or even if it is formed, very little Al oxide is formed on the outer periphery of the lower surface of 4 that is not in contact with the second mask layer, and at least on the surface side of the d3G layer on the side surface of the second mask layer 12. It is formed only to a very thin thickness.

Next, as in the case of the present invention described above with reference to FIG. , the second on its lower surface
The first mask layer 4 is etched from the outer periphery that is not in contact with the mask layer 12, and at the same time, the attached layer 6 formed on the side surface of the first mask layer 4 is removed. (Figure 2 11).

The above is the second embodiment of the method for forming a wiring structure according to the present invention.

According to the method for forming a wiring structure according to the present invention,
Although detailed explanation is omitted, similar to the method for forming the wiring structure according to the present invention described above in FIG.
Compared to the case where r15 is formed by a web etching process with side etching, it is possible to easily form the desired fine pattern.

Further, in the process of forming patterned Al1i15 from the Al layer 2 by dry etching treatment, as in the method for forming the wiring structure according to the present invention described above with reference to FIG. Even if the adhesion ff16 made of chloride is formed, the step of removing the adhesion 11a6 is not necessary in addition to the step of removing the first mask layer 4.

Note that also in the method for forming a wiring structure according to the present invention shown in FIG. 2, the second mask layer 12 is patterned as necessary. ! 5 may be removed from above.

Note that the above description merely shows two embodiments of the method for forming a wiring structure according to the present invention, and various modifications and changes may be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIGS. 1A to 1G are line sectional views showing sequential steps of a first embodiment of a method for forming a wiring structure according to the present invention. FIGS. 2A-1] are line sectional views showing sequential steps of a second embodiment of the method for forming a wiring structure according to the present invention. FIGS. 3A to 3G are cross-sectional views showing sequential steps in a conventional method for forming a wiring structure. 1...Substrate 2...Al layer 3.3', 3A, 3B, 3C111...Mask material layer 4.4', 4A, 4B, 4C, 12...Mask layer 5...Patterned Al1i6.13...Adhesion layer Fig. 3 @ Fig. 3

Claims (1)

[Claims] A step of forming an Al layer on a substrate having an insulating surface, and a first mask material layer made of Si oxide, Si nitride, Si, or a high melting point metal on the Al layer. a step of forming a first mask layer having a desired pattern on the first mask material layer; and a step of forming the first mask layer as a mask for the first mask material layer. forming a second mask layer from the first mask material layer, which has a pattern one size smaller than the first mask layer on at least the surface side, by an etching process; a step of forming a patterned Al layer as a wiring layer from the Al layer by dry etching using the first and second mask layers as masks; and etching the first mask layer.
removing the first mask layer from above the second mask layer.