JPH0817798A - Dry etching processing method for benzocyclobutene layer, and forming method for insulating layer for multilayer interconnection by it - Google Patents

Abstract

PURPOSE:To provide a method of performing the dry etching of a benzocyclobutene layer in a short time with good reproducibility, without attaching carbon to the surface of the benzocyclobutene layer. CONSTITUTION:Dry etching of a benzocyclobutene layer 63 is performed by supplying CF4 gas and O2 gas by 80sccm and l20sccm respectively as an etching gas, making the gas pressure in a reaction chamber 0.1-10 Torr, applying RF power 10-1,000W to an electrode and changing the etching gas into a reactive gas 29. Next, attachments on the surface of the benzocyclobutene after the dry etching are removed by using oxygen plasma 35, under conditions of the gas pressure in the reaction chamber 0.1-10 Torr and the RF power less than 300W.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dry etching a benzocyclobutene layer and a method for forming an insulating layer for multi-layer wiring using the same.

[0002]

2. Description of the Related Art Dry etching is performed by using a plasma etching apparatus. For example, in a parallel plate electrode type plasma etching apparatus, it is performed as follows. The reaction chamber has a high frequency applying electrode and a ground electrode, and the reaction chamber is evacuated by a vacuum pump, and then an etching gas such as CF ₄ , SF ₆ , O ₂ , N ₂ or the like is introduced. When the gas pressure in the reaction chamber is adjusted by controlling the gas flow rate and exhaust rate and a high frequency is applied to the electrodes, the etching gas is dissociated by the discharge between the electrodes and ions, electrons, neutral radicals, etc. are generated and activated. It becomes a state. Etching is performed because the highly reactive gas reacts with the sample and the reaction product is discharged as a gas.

Conventionally, polyimide has been used as an organic insulating material for multichip modules. It has excellent transmission characteristics as an organic insulating material that replaces polyimide,
Benzocyclobutene (hereinafter sometimes referred to as BCB) that is easy to process is known.

When the BCB layer is used as an insulating layer for multi-layer wiring, connection holes are formed in the BCB layer by dry etching in order to electrically connect the wirings in the multi-layer wiring. When carbon (hereinafter sometimes referred to as C) adheres to the surface of the BCB layer, the adhesion force between the BCB layer and the wiring metal (for example, Cu, Ti, Al, Cr) is determined when C is not adhered to the BCB layer. It is significantly smaller than Therefore, a mixed gas of SF ₆ and O ₂ is used as the etching gas. When a mixed gas of SF ₆ and O ₂ is used as an etching gas, this mixed gas is dissociated and C
Will never be generated. In order to prevent reaction products and radicals from adhering to the surface of the BCB layer, SF ₆ and O
Ar is added to the mixed gas of ₂ .

[0005]

However, if SF ₆ is used as the etching gas, it is difficult to match the high frequency matching of the plasma etching apparatus. Therefore, there is a limit to increase the etching rate of the BCB layer, and there is a problem that the etching of the BCB layer cannot be performed with good reproducibility.

Further, when the BCB layer is used as the insulating layer for the multilayer wiring, it is difficult to form a desired insulating layer.

Therefore, conventionally, there has been a demand for a method capable of increasing the etching rate of the BCB layer and etching the BCB layer with good reproducibility. Further, even if a BCB layer is used, the advent of a BCB etching method capable of forming a desired insulating layer has been desired.

Further, there has been a demand for a method of forming an insulating layer for a multi-layer wiring by using these BCB layer etching methods.

[0009]

In order to achieve this object, according to the dry etching method according to the first invention of this application, the BCB layer is first dry-etched using a mixed gas of CF ₄ and O _2. . Next, the deposits on the surface of the BCB layer after the dry etching are removed by using oxygen plasma.

A method of forming an insulating layer for a multi-layer wiring by using the method of dry etching the BCB layer and the method of removing the deposits on the surface of the BCB layer after the dry etching will be described.

According to the method for forming an insulating layer for a multi-layer wiring according to the second aspect of the present application, first, B is formed on the substrate via the wiring layer.
A CB layer is formed. Next, a photoresist film is formed on the BCB layer. Next, the photoresist film is patterned so as to form an opening that exposes a region where a via hole is to be formed in the BCB layer. Next, using the patterned photoresist film as a mask, the BCB layer is dry-etched with a mixed gas of CF ₄ and O ₂ to form a via hole exposing the wiring layer. Next, the patterned photoresist film is removed by dry etching using O ₂ gas. The deposits on the surface of the BCB layer, which appear after the dry etching of the BCB layer and the dry etching of the photoresist film, are removed by using oxygen plasma, so that the BCB layer in which the via holes have been formed is used as an insulating layer for multilayer wiring.

Furthermore, according to the method for forming an insulating layer for a multilayer wiring according to the third invention of this application, first, a via post is formed on a substrate via a wiring layer. Next, a BCB layer is formed so as to cover the via posts. Next, the BCB layer is dry-etched with a mixed gas of CF ₄ and O ₂ until the upper end surface of the via post appears. Next, the deposits on the surface of the BCB layer that appear after dry etching of the BCB layer are removed using oxygen plasma, so that the dry-etched BCB layer is used as an insulating layer for multilayer wiring.

[0013]

As described above, when the mixed gas of CF ₄ and O ₂ is used as the etching gas for the BCB layer, the high frequency matching of the plasma etching apparatus can be improved.

FIG. 10 is a curve diagram showing the RF power dependence of the etching rate. When using a mixed gas of CF ₄ and O ₂ as etching gas, 80s CF ₄ gas
ccm, O ₂ gas was supplied at 120 sccm, in the case of using a mixed gas of SF ₆ and O ₂ is, 80s the SF ₆ gas
ccm and O ₂ gas are supplied at 120 sccm.

According to the result of this experiment, the RF power is 900
When W, when a mixed gas of CF ₄ and O ₂ is used as an etching gas, the etching rate is about 12000Å / m.
and the etching rate is about 6000Å / m when a mixed gas of SF ₆ and O ₂ is used as the etching gas.
in. Thus, when the RF power is 900 W, the etching rate when a mixed gas of CF ₄ and O ₂ is used as the etching gas is about the same as the etching rate when a mixed gas of SF ₆ and O ₂ is used as the etching gas. It is double.

Further, by using oxygen plasma, it is possible to remove C adhering to the surface of the BCB layer after etching.

[0017]

Embodiments of the present invention will now be described with reference to the drawings.

FIGS. 1A to 1C are process drawings for explaining the first embodiment of the first invention of this application. In addition,
Each drawing is a view schematically showing a state of a main process step by a sectional cut.

After forming the BCB layer 63 on the base 61,
A photoresist film is formed on the BCB layer 63, and a resist-patterned base 69 on which the photoresist film is patterned so as to have the opening 67 is prepared. Incidentally, reference numeral 65 in the figure denotes a patterned photoresist film.

Next, the resist-patterned base 69 is formed.
Is installed in the reaction chamber of a parallel plate electrode type plasma etching apparatus (not shown). Then, the reaction chamber is evacuated (1 × 10 ⁻⁴ to 1 × 10 ⁻⁷ torr). afterwards,
A mixed gas of CF ₄ and O ₂ is introduced into the reaction chamber as an etching gas, and the gas flow rate and exhaust rate are controlled so that the gas pressure in the reaction chamber is 0.1 to 10 Torr.
RF power (10 to 1000 W) is applied to the electrode to change the etching gas to the reactive gas 29, and the BCB layer 63 is dry-etched ((A) of FIG. 1). BCB layer 63
After the etching is completed, the introduction of the mixed gas of CF ₄ and O ₂ into the reaction chamber is stopped. Then, the reaction chamber is evacuated to remove the residual gas from the reaction chamber. In the figure, 71 indicates a dry-etched BCB layer, and 73 indicates an opening ((B) of FIG. 1).

Next, O ₂ gas is introduced as an etching gas into the reaction chamber to control the gas flow rate and exhaust rate so that the gas pressure in the reaction chamber is 0.1 to 10 Torr and the RF power ( 10 to 1000 W) is applied to the electrodes to change the etching gas to the reactive gas 33, and the patterned photoresist film 65 is dry-etched. Note that this dry etching may be performed as needed.

After the patterned photoresist film 65 is removed, O ₂ gas is introduced into the reaction chamber to control the gas flow rate and exhaust rate so that the gas pressure in the reaction chamber is 0.1 to 1.
RF power (300W or less) so that it becomes 0 Torr
Is applied to the electrodes to change the O ₂ gas to oxygen plasma 35,
The oxygen plasma 35 is used to remove the deposits on the surface of the BCB layer ((C) of FIG. 1). When dry etching using the reactive gas 33 is performed, the surface of the BCB layer is mainly the upper surface of the dry-etched BCB layer 71 and the surface of the BCB layer 71 exposed in the opening 73. If not performed, the BCB layer surface is
The surface is exposed in the opening 73.

2A to 2C are process drawings for explaining the second embodiment of the first invention of this application. In addition,
Each drawing is a view schematically showing a state of a main process step by a sectional cut.

BC in which the convex material 75 is formed on the base 61, and the BCB layer 63 is formed so as to cover the convex material 75.
A base 77 on which the B layer has been formed is prepared.

Next, the BCB layer-formed underlayer 77 is placed in the reaction chamber of a parallel plate electrode type plasma etching apparatus (not shown), and then vacuum (1 × 10 ⁻⁴ to 1 × 10 ⁻⁷ to).
rr). After that, a mixed gas of CF ₄ and O ₂ is introduced into the reaction chamber as an etching gas, the gas flow rate and the exhaust rate are controlled, and the gas pressure in the reaction chamber is 0.1 to 10 T.
RF power (10 to 1000W)
Is applied to the electrode to change the etching gas into the reactive gas 29, and the BCB layer 63 is formed until the upper end surface of the convex material 75 appears.
Dry etching is performed ((A) of FIG. 2). When the etching of the BCB layer 63 is completed, the introduction of the mixed gas of CF ₄ and O ₂ into the reaction chamber is stopped. Then, in order to remove the residual gas from the reaction chamber, a vacuum is drawn inside the reaction chamber. Incidentally, reference numeral 79 in the figure denotes a dry-etched BCB layer ((B) of FIG. 2).

Next, O ₂ gas is introduced into the reaction chamber, the gas flow rate and the exhaust rate are controlled, and the gas pressure in the reaction chamber is changed to
RF power (30
(0 W or less) is applied to the electrode and O ₂ gas is supplied to oxygen plasma 35
Instead, the oxygen plasma 35 is used to remove the deposits on the surface of the BCB layer ((C) of FIG. 2).

3A to 3C and 4A to
FIGS. 5 (C), 5 (A), and 5 (B) explain a method of forming an insulating layer for a multilayer wiring, which is used to explain an embodiment of a second invention utilizing the first embodiment of the first invention of this application. It is a process drawing for doing. In addition, each drawing is a view schematically showing a state of forming an insulating layer for a multi-layer wiring in a cross-section cut in a main process step.

First, a wiring-completed substrate 17 having a wiring layer 15 formed on the first BCB layer 13 formed on the ceramics substrate 11 is prepared ((A) of FIG. 3). Pre-wired board 1
The second BCB layer 19 is formed on the wiring layer 7 via the wiring layer 15 by any one method of spin coating, bar coating, and roll coating. After that, half cure (about 2
The temperature is set to 00 ° C. for 30 to 120 minutes to obtain a structure as shown in FIG. In this embodiment, the wiring layer is formed by electrolytic plating using Cu as the wiring metal.

Next, a photoresist is coated on the second BCB layer 19 and prebaked to form a photoresist film 21 ((C) in FIG. 3). In this example,
A positive resist based on novolac resin is used as the photoresist.

Next, the photoresist film 21 is patterned so as to form the opening 23 exposing the via hole formation planned region of the second BCB layer 19 ((A) of FIG. 4). In the figure, 25 indicates a patterned photoresist film.

Next, the resist-patterned substrate 27
Is installed in the reaction chamber of a parallel plate electrode type plasma etching apparatus (not shown). Then, the reaction chamber is evacuated (1 × 10 ⁻⁴ to 1 × 10 ⁻⁷ torr). afterwards,
A mixed gas of CF ₄ and O ₂ is introduced into the reaction chamber as an etching gas, and the gas flow rate and exhaust rate are controlled so that the gas pressure in the reaction chamber is 0.1 to 10 Torr.
RF power (10 to 1000 W) is applied to the electrodes to change the etching gas into the reactive gas 29, and the second BCB layer 19
Dry etching is performed (FIG. 4B). Second BC
After etching the B layer 19, the introduction of the mixed gas of CF ₄ and O ₂ into the reaction chamber is stopped. Then, the reaction chamber is evacuated to remove the residual gas from the reaction chamber. In the figure, 31 indicates a dry-etched second BCB layer, and 34 indicates a via hole ((C) of FIG. 4).

Next, O ₂ gas as an etching gas is introduced into the reaction chamber, the flow rate and exhaust speed of the gas are controlled so that the gas pressure in the reaction chamber is 0.1 to 10 Torr, and the RF power ( 10 to 1000 W) is applied to the electrodes to change the etching gas to the reactive gas 33, and the patterned photoresist film 25 is dry-etched ((C) of FIG. 4). At this time, it is known that the BCB layer is hardly etched by the reactive gas of O ₂ gas. Compared with BCB, photoresist has a very low resistance to O ₂ gas and its reactive gas, and therefore a large etching selection ratio can be obtained.

After the patterned photoresist film 25 is removed, O ₂ gas is introduced into the reaction chamber to control the gas flow rate and exhaust rate so that the gas pressure in the reaction chamber is 0.1 to 1.
RF power (300W or less) so that it becomes 0 Torr
Is applied to the electrodes to change the O ₂ gas to oxygen plasma 35,
The oxygen plasma 35 is used to remove the deposits on the surface of the BCB layer ((A) of FIG. 5). As deposits to be removed,
There are the following. Product when etching the second BCB layer 19, patterned photoresist film 2
5, a radical generated from an etching gas used to etch the second BCB layer 19, a radical generated from an etching gas used to etch the patterned photoresist film 25, and the like. C is also contained in these deposits.

Through these steps, the insulating layer 37 for multilayer wiring is formed (FIG. 5B).

6A to 6C and 7A to 7C.
(C), FIG. 8 (A)-(C), and FIG. 9 are the 1st of this application.
FIG. 9 is a process chart for explaining a method for forming an insulating layer for a multilayer wiring, which is used for describing an example of a third invention using the second example of the invention. In addition, each drawing is a view schematically showing a state of forming an insulating layer for a multi-layer wiring in a cross-section cut in a main process step.

First, a method of forming via posts will be described. A first BCB layer-formed substrate 42 in which the first BCB layer 13 is formed on the ceramic substrate 11 is prepared (FIG. 6).
(A)). BC is formed on the substrate 42 on which the first BCB layer is formed.
A current film (not shown) is formed through the B layer 13. In this embodiment, the current film is made of Cu and is formed by the sputtering method. Next, on the current film, the wiring layer 1 is formed by using Cu and electrolytic plating.
5 is formed ((B) of FIG. 6). Next, a photoresist film 41 is formed so as to cover the wiring layer and the current film ((C) of FIG. 6). After that, the photoresist film is patterned to form an opening 43 for forming a via post on the wiring layer ((A) of FIG. 7). Reference numeral 45 in the drawing denotes a patterned photoresist film. Next, the via post 4 is formed in the opening 43 by electrolytic plating using Cu.
7 is formed ((B) of FIG. 7). In this embodiment, the current film, the wiring layer and the via post are formed by using the same material. Next, after removing the patterned photoresist film, the current film is removed. As a result, a structure as shown in FIG. 7C is obtained.

Using the via post 47 thus formed, an insulating layer for multilayer wiring is formed as follows. Second B so as to cover the wiring layer 15 and the via post 47.
The CB layer 49 is formed by using one of spin coating, bar coating, and roll coating, and is subjected to half cure (about 200 ° C. for 30 to 120 minutes), as shown in FIG. To obtain a simple structure.

Next, the second BCB layer-formed substrate 51 is placed in a reaction chamber of a parallel plate electrode type plasma etching apparatus (not shown), and then vacuum (1 × 10 ⁻⁴ to 1 × 10 ^{−7) is set.}
torr). After that, CF is used as an etching gas.
A mixed gas of ₄ and O ₂ is introduced into the reaction chamber, the gas flow rate and the exhaust speed are controlled, and the gas pressure in the reaction chamber is 0.1 to 1
RF power (10 to 1000)
W) is applied to the electrode and etching gas is used as reactive gas 29
Change to 2B until the upper end surface of the via post 47 appears.
Dry etching of the CB layer 49 is performed ((B) of FIG. 8). After the etching of the second BCB layer 49 is completed, the introduction of the mixed gas of CF ₄ and O ₂ into the reaction chamber is stopped. Then, in order to remove the residual gas from the reaction chamber, a vacuum is drawn inside the reaction chamber. Incidentally, reference numeral 53 in the drawing denotes a dry-etched second BCB layer ((C) of FIG. 8).

Next, O ₂ gas is introduced into the reaction chamber, the gas flow rate and the exhaust rate are controlled, and the gas pressure in the reaction chamber is changed to
RF power (30
(0 W or less) is applied to the electrode and O ₂ gas is supplied to oxygen plasma 35
Instead, the oxygen plasma 35 is used to remove the deposits on the surface of the second BCB layer ((C) of FIG. 8).

Through these steps, the insulating layer 55 for multilayer wiring is formed (FIG. 9).

Obviously, the invention is not limited to the embodiments described above. For example, in each of the above-described embodiments, ceramics was used as the substrate, but Si
A wafer or glass may be used. Further, although the current film, the via post and the wiring layer are formed using Cu, they may be formed using Cr, Ti, Al, Ni or Au. Further, although the wiring layer and the via post are formed by the electrolytic plating method, they may be formed by the sputtering method, the vapor deposition method, or the electroless plating method.

Here, the dry etching method of the BCB layer according to the first invention is applied to the case of forming the insulating layer for the multilayer wiring, but it is used for all processes using the BCB layer, for example, a magnetic hard disk or a liquid crystal display. It can be applied to a process of forming an insulating layer or a surface protective film.

[0043]

As is apparent from the above description, according to the dry etching method for the BCB layer according to the present invention, since the mixed gas of CF ₄ and O ₂ is used as the etching gas, the RF power is increased. However, the high frequency matching of the plasma etching apparatus can be easily matched. Further, the high frequency of the plasma etching apparatus is constant depending on the position inside the reaction chamber. From these things, when a mixed gas of CF ₄ and O ₂ is used as an etching gas,
The BCB layer can be etched faster than when a mixed gas of SF ₆ and O ₂ is used as an etching gas. In addition, etching of the BCB layer can be performed with good reproducibility.

Further, since the deposit on the surface of the BCB layer after etching is removed by using oxygen plasma, there is no problem of depositing C on the surface of the BCB layer.

When the dry etching method for the BCB layer according to the first invention of this application is used to form an insulating layer for a multilayer wiring, a desired insulating layer can be formed.

[Brief description of drawings]

1A to 1C are process diagrams for explaining a first embodiment of the first invention.

FIG. 2A to FIG. 2C are process drawings for explaining a second embodiment of the first invention.

3A to 3C are process drawings for explaining an embodiment of a second invention utilizing the first embodiment of the first invention.

4A to 4C are process diagrams subsequent to FIG. 3 for explaining an embodiment of a second invention utilizing the first embodiment of the first invention.

5A and 5B are process diagrams following FIG. 4 for explaining an embodiment of a second invention using the first embodiment of the first invention.

6A to 6C are process drawings for explaining an embodiment of a third invention utilizing the second embodiment of the first invention.

7A to 7C are process diagrams following FIG. 6 for explaining an embodiment of a third invention utilizing the second embodiment of the first invention.

8A to 8C are process diagrams subsequent to FIG. 7 for explaining an embodiment of a third invention using the second embodiment of the first invention.

9 is a process diagram following FIG. 8 for explaining an embodiment of the third invention utilizing the second embodiment of the first invention. FIG.

FIG. 10 is a curve diagram showing RF power dependence of etching rate.

[Explanation of symbols]

 11: Substrate 13: First BCB Layer 15: Wiring Layer 17: Wiring Substrate 19: Second BCB Layer 21: Photoresist Film 23: Opening 25: Patterned Photoresist Film 27: Resist Patterned Substrate 29: Reactive Gas 31: Dry Etching Completed second BCB layer 33: Reactive gas 34: Via hole 35: Oxygen plasma 37: Insulation layer for multilayer wiring 41: Photoresist film 42: First BCB layer formed substrate 43: Opening 45: Patterned photoresist film 47: Via post 49: No. 2 BCB layer 51: Second BCB layer formed substrate 53: Dry-etched second BCB layer 55: Multilayer wiring insulating layer 61: Underlayer 63: BCB layer 65: Patterned photoresist film 67: Opening 69: Patterned underlayer 71: Dry etching Already B B layer 73: opening 75: convex material 77: BCB layer already formed underlying 79: dry etched BCB layer

Claims (3)

[Claims] 1. A step of dry-etching a benzocyclobutene layer using a mixed gas of CF ₄ and O ₂ , and a step of removing deposits on the surface of the benzocyclobutene layer after dry etching using oxygen plasma. And a dry etching treatment method for a benzocyclobutene layer. 2. A step of forming a benzocyclobutene layer on a substrate via a wiring layer, a step of forming a photoresist film on the benzocyclobutene layer, and exposing a via hole formation planned region of the benzocyclobutene layer. Patterning the photoresist film so as to form an opening; and using the patterned photoresist film as a mask, dry-etch the benzocyclobutene layer with a mixed gas of CF ₄ and O ₂ to form the wiring layer. A step of forming an exposed via hole; a step of removing the patterned photoresist film by dry etching using O ₂ gas; a step of removing benzocyclobutene after the benzocyclobutene layer and the photoresist film by dry etching; Oxygen plasma is used to remove the deposits on the butene layer surface. There, by removing the steps of the benzocyclobutene layer of the via hole has been formed as a multilayer wiring insulating layer,
A method for forming an insulating layer for multi-layer wiring, comprising: 3. A step of forming a via post on a substrate via a wiring layer, a step of forming a benzocyclobutene layer so as to cover the via post, and a step of forming a benzocyclobutene layer on the via post by a mixed gas of CF ₄ and O _2. A step of dry-etching the benzocyclobutene layer until an end surface appears, and a deposit on the surface of the benzocyclobutene layer that appears after the dry etching of the benzocyclobutene layer is removed using oxygen plasma to obtain a dry-etched product. A step of forming the benzocyclobutene layer as an insulating layer for multilayer wiring, the method for forming an insulating layer for multilayer wiring.