JPH08330283A - Contact hole formation of semiconductor - Google Patents

Abstract

PURPOSE: To surely remove polymer which is formed by etching of a contact hole by performing after-treatment for a resist lower layer part remaining on a wafer and a contact hole inner surface by amine organic solvent. CONSTITUTION: Half etching is performed by etching treatment wherein oxygen plasma is used leaving a lower layer part of resist 4 until a top part of a crown 7 projects on the resist layer 4. Then, a wafer is immersed in amine organic solvent. The amine organic solvent contains 2-(2-aminoethoxy)ethanol having resist removal function. Therefore, a resist layer 4 on a layer insulation film 2 is peeled while metallic polymer is removed. The crown 7 joined to the resist 4 is also lifted up together with the resist 4 and is peeled and removed from the side of a foundation 1 as the resist 4 is removed.

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 contact holes in a semiconductor device. More specifically, the present invention relates to a method of post-processing the inside of a hole after forming the contact hole by etching.

[0002]

2. Description of the Related Art In a multilayer wiring structure of a semiconductor device, an upper metal wiring layer is formed on an underlying silicon substrate or a lower wiring layer via an interlayer insulating film, and the metal wiring layer is formed on the interlayer insulating film. It conducts with the underlying silicon substrate or lower wiring layer through the contact hole (or via hole). Such a contact hole is formed in the interlayer film by performing resist patterning after forming an interlayer insulating film on the base and performing ion etching such as RIE using a reaction gas. The interlayer film is usually made of SiO2, and a fluorine-based gas such as CF4 is used as an etching reaction gas. During this etching process, a reaction product of the reaction of the reaction gas with the interlayer film and the base material is deposited as a polymer called a crown on the inner surface of the contact hole in a ring shape or a cylinder shape.

The crown made of this polymer is produced as an organic polymer when the underlayer is single crystal silicon or polysilicon or when etching a resist or an interlayer film, and the underlayer etches metals such as Al, Ti and TiN. In some cases, it is produced as a metal-based polymer.
Since such a crown protrudes onto the interlayer film after the resist is removed, when aluminum wiring is laminated in the next step, there is a possibility that wiring resistance may change or coverage may be deteriorated, resulting in deterioration of quality and characteristics. Therefore, it is necessary to remove such a crown after forming the contact hole by etching.

Conventionally, in order to remove the crown by this polymer, the resist on the interlayer insulating film is completely removed by sulfuric acid / hydrogen peroxide (H2SO4 + H2O2), and then the wafer is dipped in an amine-based organic solvent. The polymer crown around the contact hole is chemically post-treated to remove the crown.

[0005]

However, in the above-mentioned conventional post-treatment method for removing a crown with an amine-based organic solvent, although the metal-based polymer was sufficiently removed, the removal of the organic-based polymer was completed. This could affect the quality and characteristics of aluminum wiring. This is because the metal-based polymer can be efficiently removed because the amine group of NH2OH contained in the amine-based organic solvent has high reactivity to the metal-based material, but the amine-based organic solvent is reactive to the organic-based polymer. This is because the polymer remains as a residue and remains on the periphery of the contact hole.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide a method for forming a contact hole including a post-treatment step capable of surely removing a polymer formed by etching a contact hole. To do.

[0007]

In order to achieve the above object, according to the present invention, (a) a step of forming an interlayer insulating film on a metal wiring layer formed on a wafer, and (b) the interlayer insulating film. A step of forming a resist pattern thereon, (c) a step of etching the interlayer insulating film through the resist pattern to form a contact hole, and (d) a resist leaving a lower layer portion of the resist by oxygen plasma And a step of (e) post-treating the resist lower layer portion and the contact hole inner surface remaining on the wafer with an amine-based organic solvent, (e) providing a contact hole forming method for a semiconductor device. To do. In a preferred embodiment, the metal wiring layer is made of an aluminum alloy.

[0008]

When the contact hole is formed by etching, the polymer is formed on the inner surface of the contact hole so as to protrude up to the height of the resist layer. By the half etching treatment with oxygen plasma, the upper layer of the resist is removed, for example, leaving the lower layer of the resist layer until the top of the polymer appears. As a result, the resist remains on the interlayer film in a state where the polymer and the resist are bonded. By immersing this in an amine-based organic solvent, the resist is removed, and at the same time, the crown bonded to the resist is physically lifted together with the resist and peeled off from the substrate side. This is because the resist is removed by 2 (2aminoethoxy) ethanol contained in the amine-based organic solvent. As a result, the crown of the organic polymer is physically removed together with the metal-based polymer. Further, the metal-based polymer is also chemically removed by the action of the amino group in the amine-based organic solvent as described above.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a flow chart of a manufacturing process by a method for forming a contact hole of a semiconductor device according to an embodiment of the present invention, and FIGS. 2 and 3 are cross-sectional views of a main part of a contact hole in each step of this manufacturing process. First, step S1
2A, a metal wiring layer, for example, an aluminum wiring layer 2 is formed on a base 1 of a silicon substrate or a lower wiring layer as shown in FIG. An interlayer insulating film 3 made of, for example, SiO2 is formed on the aluminum wiring layer 2. A resist is applied and patterned on the entire surface of the interlayer insulating film 3,
A resist layer 4 having a hole pattern 5 is formed (step S2).

Next, as shown in FIG. 2B, an interlayer insulating film 3 is formed by ion etching such as RIE using a reactive gas.
To form a contact hole 6. (Step S3). An example of contact hole etching conditions at this time is as follows.

Gas: CHF3 / CF4 / Ar = 50/30/10 sccm Pressure: 6.5 Pa RF power density: 0.2 W / cm ² Temperature: 50 ° C. During this etching process, the reaction gas is an interlayer insulating film 3 or a resist. 4 and the substrate 1 to generate a reaction product as a polymer. This polymer is deposited on the inner surface of the contact hole 6 in a ring shape or a cylindrical shape to form a crown 7 as shown in FIG. 2 (B). The polymer called the crown 7 is generated as an organic polymer when the underlayer 1 made of single crystal silicon or polysilicon is etched or when the resist 4 and the interlayer insulating film 3 are etched. When the underlayer 1 made of a metal such as Al, Ti or TiN is etched, it is produced as a metal-based polymer. When the crown 7 is formed, a large amount of organic polymer is deposited on the inner surface of the contact hole 6 at the initial stage of etching because the resist and the interlayer insulating film are etched, and when the underlying metal appears thereafter, a large amount of metal polymer is deposited. To do.

Then, as shown in FIG. 2C, half etching is performed by etching using oxygen plasma, leaving the lower layer of the resist 4 to the extent that the top of the crown 7 projects above the resist layer 4 ( Step S4).

An example of the half etching conditions at this time is as follows.

Oxygen: 100 sccm Pressure: 27 Pa RF power density: 300 W / cm ² Temperature: 100 ° C. Next, in step S5, the wafer is immersed in an amine organic solvent.

An example of the dipping condition of the wafer at this time is as follows.

Time: 15 min Temperature: 65 ° C. This amine-based organic solvent contains, as described above, 2 (2aminoethoxy) ethanol having a resist removing action together with the amino group of NH 2 OH which has high reactivity with metal-based substances. Has been. Therefore, the metal-based polymer is removed and the resist layer 4 on the interlayer insulating film 2 is peeled off. Along with the peeling of the resist 4, the crown 7 joined to the resist 4 is also lifted up together with the resist 4, and peeled off from the base 1 side and removed. As a result, the organic polymer portion of the crown 7 is physically removed together with the metal-based polymer. Further, the remaining metal-based polymer is chemically removed by the action of the amino group of the amino-based organic solvent.

Next, in step S6, the wafer chemically treated with the amino-based organic solvent is washed with pure water for a predetermined time, for example, 10 minutes, and then the surface is dried and washed with IPA or the like. Thereafter, as shown in FIG. 3E, the contact hole 6 is filled with tungsten 8 by a blanket W method or the like, and an aluminum wiring layer 9 is formed thereon.

In the above-mentioned embodiment, the aluminum wiring layer is used as the metal wiring layer, but this is not limited to aluminum alone, but Al-Si or Al-Cu, Al-Cu-.
It may be formed of an aluminum alloy such as a Si alloy, tungsten, or another metal material.

[0019]

As described above, according to the method of forming a contact hole of a semiconductor device of the present invention, the polymer formed in the contact hole is formed on the wafer by an amine organic solvent after half etching of the resist by oxygen plasma. The remaining resist lower layer portion and the polymer are simultaneously lifted off, and the amine-based organic solvent chemically removes the remaining polymer, so that the polymer formed on the inner surface of the contact hole is surely removed. As a result, the step coverage can be improved, the contact resistance can be prevented from increasing, the quality of the semiconductor device can be expected to be improved, and the yield can be improved.

Further, the present invention can be used for removing the polymer formed when forming a wiring pattern. In this case, an aluminum oxide film is formed by etching with oxygen plasma, so that corrosion can be prevented by an amine-based organic solvent in the subsequent steps.

[Brief description of drawings]

FIG. 1 is a flowchart showing a manufacturing process of a semiconductor device contact hole forming method according to an embodiment of the present invention.

FIG. 2 is a sectional view sequentially showing a process of forming a contact hole of a semiconductor device according to an exemplary embodiment of the present invention.

3A to 3C are cross-sectional views sequentially showing a process of forming a contact hole of the semiconductor device according to the exemplary embodiment of the present invention, following FIG.

[Explanation of symbols]

1: base, 2: aluminum wiring layer, 3: interlayer insulating film, 4: resist layer, 5: hole pattern, 6: contact hole, 7: crown, 9: aluminum wiring layer.

Claims (2)

[Claims] 1. A step of: (a) forming an interlayer insulating film on a metal wiring layer formed on a wafer; (b) forming a resist pattern on the interlayer insulating film; and (c) the resist. A step of etching the interlayer insulating film through a pattern to form a contact hole; (d) a step of etching the resist with oxygen plasma leaving a lower layer portion of the resist; and (e) an amine-based organic solvent. And a step of post-processing a resist lower layer portion and a contact hole inner surface remaining on the wafer, the method of forming a contact hole in a semiconductor device. 2. The method of forming a contact hole in a semiconductor device according to claim 1, wherein the metal wiring layer is made of an aluminum alloy.