JP3277652B2 - Dry etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching method, and more particularly to, for example, a multi-layer resist process for preventing an undercut when forming a resist pattern by anisotropically processing a lower resist which is an organic material layer. The present invention relates to a method for forming a lower resist pattern having no conversion difference.

[0002]

2. Description of the Related Art With the miniaturization of design rules for semiconductor devices such as LSIs from half micron to quarter micron, the demands on fine processing techniques such as photolithography and dry etching are becoming more severe. . In photolithography technology, in recent years, in order to achieve fine design rules, the exposure wavelength has been shortened in search of high resolution, and the surface step of the underlying substrate has been increasing to adopt a multilayer wiring structure. It is becoming essential to adopt a multilayer resist process. The multilayer resist process includes a lower resist having a thickness sufficient to absorb a surface step of the underlying substrate and form a flat surface,
A thin intermediate layer made of an inorganic material for forming a substantial mask pattern when etching the lower layer resist,
The concept of a so-called three-layer resist process that is used in combination with an overlying resist that is thin enough to achieve high resolution has been described by JMMorran et al. In J. Vac. Sci. Technol., 16 , 1620.
(1979). A detailed commentary on the dry etching method of the multilayer resist is published in Monthly Semiconductor World Magazine, November 1987, pages 101 to 106.

A method for forming a resist pattern by a three-layer resist process will be described with reference to FIG.

FIG. 2A shows a sectional shape of a substrate to be etched on which an upper resist pattern 5 is formed in a three-layer resist process. That is, first, this step is formed on the interlayer insulating film 1 having a step, for example, Al.
An underlayer material layer 2 made of an alloy or the like is formed, a lower resist layer 3 having a thickness sufficient to absorb the steps and form a flat surface, and an SiO ₂ intermediate layer made of, for example, spin-coated glass (SOG). Layer 4, and further this intermediate layer 4
A thin upper resist layer is sequentially formed thereon in this order. This upper resist layer is patterned by photolithography and development to obtain the resist pattern 5 described above. Since the photolithography at this time is exposure to a flat surface, the resolution is high.
It has a clear rectangular shape with a width of 35 μm.

Next, the intermediate layer 4 is patterned by RIE using the upper resist pattern 5 as a mask.
An intermediate layer pattern 4a is formed as shown in FIG. This intermediate layer pattern 4a also has a clear rectangular shape with a width of 0.35 μm.

Next, using the upper resist pattern 5 and the intermediate layer pattern 4a as a mask, the lower resist layer 3 is anisotropically etched using O ₂ gas, thereby forming the desired lower layer as shown in FIG. A resist pattern 3a is formed. In this etching process, the thin upper resist pattern 5 is etched off halfway and disappears.

Thereafter, the underlying material layer 2 is patterned by anisotropic etching such as RIE using the lower resist pattern 3a as a mask to obtain a desired, for example, Al alloy wiring pattern (not shown). At this time, the lower material layer may be etched while leaving the intermediate layer pattern 4a, or may be separately removed and the lower material layer 2 may be etched only by the lower resist pattern 3a. By performing such a multi-layer resist process, it becomes possible to form a base material layer having good controllability even on a stepped substrate, for example, an Al alloy wiring pattern.

As described above, RIE using O ₂ gas is generally used for etching the lower resist layer 3. The lower resist layer 3 is a layer formed to have a thickness sufficient to absorb the surface steps of the substrate to be etched based on the purport of the three-layer resist process, and therefore requires high-speed etching. Therefore, when high gas pressure conditions are used to improve the etching rate and oxygen radicals (hereinafter, referred to as O ^* ) are increased and etching is performed mainly by radical reaction, O ^* reaches the lower portion of the intermediate layer pattern 4a, Undercut due to the isotropic oxidation reaction occurs, and the shape of the lower resist pattern 3a deteriorates.

On the other hand, in order to prevent undercut of the lower layer resist and achieve high anisotropic etching, conditions such as low gas pressure and high bias power, which increase the mean free path of ions and the substrate bias, are adopted. It is necessary. In other words, highly anisotropic etching is performed by performing ion mode etching while using sputtering in combination with normal incidence and large kinetic energy of oxygen ions (hereinafter referred to as O ⁺ ). However,
The use of such etching conditions causes difficulty in obtaining a high etching rate and lowers the selectivity with respect to the underlying material layer. The underlying material layer is sputtered, and part of the sputtering is performed on the side wall of the lower resist pattern 3a. Adhere to. This problem will be described with reference to FIG.

FIG. 3 shows a state in which the lower resist pattern 3a is completed by strong ion mode etching. The lower resist pattern above the step is formed early because it is thin. Then, the exposed underlying material layer 2 above the step is continuously subjected to the undesired irradiation of O ⁺ until the lower resist pattern below the step is formed. For this reason, the base material layer 2 is sputtered, and a part thereof adheres to the side wall of the lower resist pattern 3a to form the reattached material layer 2a. In particular, when the base material layer 2 is a metal wiring material layer containing Cu, it is difficult to remove the reattachment layer 2a, and remains on the substrate to become a source of particle contamination.
Further, since the reattachment layer thickens the substantial line width of the lower resist pattern 3a, a dimensional conversion difference is likely to occur when the underlying material layer is etched.

[0011] The above-mentioned problem of the redeposition layer is, for example, the third problem.
The 3rd Joint Lecture on Applied Physics (Spring Annual Meeting, 1986) is well known, as pointed out in Proceedings, p.542, Lecture No. 2p-Q-8. It is clear that reducing the incident ion energy is effective in suppressing the formation of the reattachment layer, but in this case, the above-mentioned isotropic reaction predominates,
Anisotropy decreases and undercut occurs.

Therefore, the incident ion energy can be reduced, and
There is a long-felt need for a method of dry-etching a lower resist layer that is compatible with achieving high anisotropy.

As a technique for responding to such a demand, the present applicant has heretofore achieved not only the reduction of the radical component and the enhancement of the ionic component alone but also the formation of the sidewall protective film by the reaction product of the etching. Has applied for an invention based on the idea of achieving a highly anisotropic shape by utilizing the above. That is, when the sidewall protective film is used in combination, the ion incident energy can be reduced while covering the attack of O ^* and securing the etching rate to a practically acceptable level.

For example, Japanese Patent Application Laid-Open No. Hei 2-244625 discloses O_Two
Use etching gas with Cl-based gas added
As a result, C, which is a reaction product between the resist and the Cl-based gas,
Cl _xLower resist layer while depositing as a sidewall protective film
A technique for performing anisotropic etching of the above was shown.

Japanese Patent Application Laid-Open No. 4-0841414 proposes a technique in which a substrate temperature is controlled to 50 ° C. or lower and a resist material layer is etched using an etching gas mainly composed of NH ₃ . According to this method, a reaction product containing N, C, and O as constituent elements plays a role of a sidewall protective film.

Further, Japanese Patent Application Laid-Open No. Hei 4-117726 discloses O_Two
Using an etching gas containing a Br-based gas
As a result, C, which is a reaction product between the resist and the Br-based gas,
Br _xLower resist layer while depositing as a sidewall protective film
A technique for performing anisotropic etching of the above has been disclosed.

[0017]

The above-mentioned dry etching methods, which the applicant of the present invention has filed earlier, provide a practical etching rate and, in a practical temperature range, anisotropic etching with low ion energy. It is a revolutionary technology in achieving With these techniques, re-adhesion of the underlying material layer to the side wall of the lower resist pattern due to sputtering has been greatly suppressed.

However, in the future, when the integration of devices is further advanced and an attempt is made to perform anisotropic processing of a finer lower resist pattern, there is a concern that a difference in the processing size may become apparent. This problem will be described with reference to FIG.

FIG. 4A shows a state in which the lower resist has been etched partway using the upper resist pattern and the intermediate layer pattern 4a as a mask. Are formed. This side wall protective film 6 is made of carbon supplied from the upper resist pattern and the lower resist 3,
It is a reaction product with an etching gas, prevents undercut of the lower resist pattern, and contributes to anisotropic processing. However, once the upper resist pattern is once etched off and the intermediate layer 4a is exposed, the supply of the reaction product is greatly reduced, so that the sidewall protective film necessary for anisotropic processing of the lower resist layer is formed. However, when the etching of the remaining portion 3b of the lower resist layer is continued, a phenomenon that the undercut 7 occurs often occurs. The occurrence of the difference in the processing size conversion of the lower resist pattern 3a due to the undercut 7 is becoming an obstacle to the practical use of the multilayer resist process.

Accordingly, an object of the present invention is to prevent an undercut caused by a decrease in the supply amount of an etching reaction product before and after etch-off of an upper-layer resist in patterning of a lower-layer resist in a multilayer resist process. An object of the present invention is to provide a dry etching method excellent in anisotropy.

Another object of the present invention is to provide a clean dry etching method that prevents re-adhesion to the side wall of a lower resist pattern due to sputtering of a base material layer and that does not cause particle contamination.

Still another object of the present invention is to achieve the above object while ensuring a practical etching rate.

[0023]

SUMMARY OF THE INVENTION The dry etching method of the present invention has been proposed to solve the above-mentioned problem. The dry etching process for the lower resist layer is divided into two stages, and the upper resist pattern is etched off. And a second dry etching step after the upper resist pattern is etched off. The second dry etching step is different from the first dry etching step. Conditions were used.

Further , the first dry etching step and the second
Dry etching process means the plasma generation power (example
For example, microwave power) and substrate bias power (for example,
RF bias power) and plasma energy that can be individually controlled.
This is performed as follows using a switching device.

That is, the dry etching method of the present invention uses a mixed gas containing an oxygen gas and a halogen-based gas,
The second etching step is performed more than the first etching step.
Plasma generation power while lowering etching pressure
To be performed with a higher pressure.

The dry etching method of the present invention further comprises
Using a mixed gas containing oxygen gas and halogen gas, a second
In the etching step, argon gas is used as an etching gas.
It was configured to be added.

The dry etching method of the present invention uses a mixed gas containing an oxygen gas and a halogen-based gas,
The second etching step is performed more than the first etching step.
The configuration is performed by increasing the substrate bias power.

[0028]

The point of the present invention is that the etching of the lower resist layer is divided into two stages, a first etching process until the upper resist is etched off, and a second etching process after the upper resist is etched off. And the conditions of the second etching step are different from those of the first etching step. Thus, even after the upper resist pattern is etched off, the weakening of the function of forming the sidewall protective film due to the insufficient supply of the etching reaction product can be compensated, and the undercut of the lower resist pattern can be prevented.

In the present invention, the etching is performed using a mixed gas of, for example, oxygen gas and a halogen-based gas so that the etching reaction product contributes to the formation of the sidewall protective film. By increasing the mixing ratio of the system gas, it is possible to prevent O ^*, which is an unreacted etching active species, from being excessively present. At the same time, the etching reaction products CCl _x and CBr
_This promotes the generation of _{x and the} like, and strengthens the sidewall protective film. Thereby, undercut of the lower resist pattern can be prevented.

Further, in the present invention, etching is performed using a mixed gas of oxygen gas and halogen-based gas, and the mean free path of O ⁺ is increased by lowering the etching pressure in the second etching step. Utilizing the high kinetic energy of the ions, anisotropic etching is achieved and undercut is prevented.

Further, in the present invention, the concentration of O ^* , which is an etching active species, is increased by etching using a mixed gas of oxygen gas and halogen-based gas, and adding a rare gas in the second etching step. Is relatively reduced, whereby undercutting of the lower resist pattern can be prevented.

In the present invention, the etching is performed using a mixed gas of oxygen gas and a halogen-based gas, and in the second etching step, the kinetic energy of the ions is increased by increasing the substrate bias voltage, thereby increasing the anisotropy. The etching is achieved and the undercut is prevented.

As a technical idea of dividing the etching conditions into two stages when patterning the lower resist in the three-layer resist process, as one example, a method of changing the etching conditions after partially exposing the base material layer is known. . That is, the over-etching conditions are changed to prevent, for example, damage to the underlying material layer. The conventional two-step etching described here is different from the technical idea of the present invention that compensates for the reduction of the reaction products involved in the formation of the sidewall protective film when the upper resist layer is etched.

[0034]

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

Embodiment 1 In this embodiment, Al-1 is used in a three-layer resist process.
In the case where the lower resist layer formed on the base material layer made of the% Si-0.5% Cu alloy is patterned by using a mixed gas of O ₂ and Cl ₂ , the etching is divided into two steps and the upper resist pattern is formed. C is etched off after
This is an example in which etching is performed by increasing the mixing ratio of l ₂ .
This dry etching method will be described with reference to FIG.
In the figure, the same parts as those described in the related art are denoted by the same reference numerals.

First, as shown in FIG. 1A, as a substrate to be etched, a stepped SiO ₂ -based interlayer insulating film 1 formed on a Si wafer having a diameter of, for example, 5 inches is formed.
The Al-1% Si-0.5% Cu alloy layer 2 having the steps is provided with an O.D. It is formed to a thickness of 7 μm, and this is used as a base material layer. Here, the lower wiring and the like below the interlayer insulating film 1 are not shown. Next, a lower resist layer 3 is formed by applying a novolak-based positive photoresist (trade name: OFPR-800, manufactured by Tokyo Ohka Kogyo Co., Ltd.) as an example. Here, the thickness of the lower resist layer 3 in the region corresponding to the lower part of the step is about 1.0 μm, and the surface is formed so as to absorb the step and become a flat surface. SOG (trade name: OCD-Type2, manufactured by Tokyo Ohka Kogyo Co., Ltd.) is spin-coated on the lower resist layer 3 to have a thickness of about 0.
An SiO ₂ -based intermediate layer 4 of ₂ μm is formed. Further, an upper resist pattern 5 patterned in a predetermined shape is formed on the intermediate layer 4. The upper resist pattern 5 is made of, for example, a negative chemically amplified resist (trade name: SAL-601, manufactured by Shipley) having a thickness of about 0.7 μm.
It is formed by performing KrF excimer laser exposure and development processing on the coating film of m. The pattern width of the upper resist pattern 5 is, for example, 0.35 μm.

Next, the substrate to be etched is set in, for example, a hexagonal dry etching apparatus, and the intermediate layer 4 is etched using the upper resist pattern 5 as a mask. The etching conditions at this time were as follows, for example. CHF ₃ 75 sccm O ₂ 8 sccm Gas pressure 6.5 Pa RF bias power 1350 W (13.56 MH)
z) As a result, as shown in FIG. 1B, an intermediate layer pattern 4a was formed immediately below the upper resist pattern 5.

Next, the substrate to be etched was transferred to an RF bias applying type ECR plasma etching apparatus, and the lower resist layer 3 was etched under the following conditions as an example. O ₂ 40 sccm Cl ₂ 10 sccm Gas pressure 2.0 Pa Microwave power 900 W (2.45 GHz) RF bias power 200 W (2 MHz) Substrate temperature Room temperature

In the above etching process, the lower resist layer 3 is etched by a mechanism in which the isotropic oxidation reaction by O ^* is assisted by ions such as O ⁺ and Cl ⁺ , and at the same time, the etching of the upper resist pattern 5 is also performed. proceed. The etching gas and the upper resist pattern 5
A reaction product CCl _x is generated due to a carbon-based decomposition product supplied from the lower resist layer 3, and this is polymerized in plasma to generate a carbon-based plasma polymer. This carbon-based plasma polymer is deposited on the pattern side wall to form the side wall protective film 6 and contributes to anisotropic etching. As a result, as shown in FIG. 1C, a lower resist pattern having an anisotropic shape was formed halfway.

In the first etching step, the upper resist pattern 5 is also etched off, exposing the intermediate layer pattern 4a. However, at this stage, the remaining portion 3b of the lower resist layer still exists.

Therefore, the etching conditions are switched as follows as an example, and the remaining portion 3b of the lower resist layer is etched. O ₂ 20 sccm Cl ₂ 30 sccm Gas pressure 2.0 Pa Microwave power 900 W (2.45 GHz) RF bias power 200 W (2 MHz) Substrate temperature Room temperature In the second etching step, the mixing ratio of O ₂ is reduced. Then, the mixing ratio of Cl ₂ was increased, and the other etching conditions were the same. That is, excessive unreacted O ^* due to etching off of the upper resist pattern is prevented from being excessively present, and at the same time, generation of CCl _x functioning as a sidewall protective film is promoted. As a result, as shown in FIG.
The lower resist pattern 3a was formed without undercut and maintaining an anisotropic shape.

Embodiment 2 In this embodiment, when the lower resist layer is similarly etched by using a mixed gas of O ₂ and HCl, the etching is divided into two stages, and after the upper resist pattern is etched off, the etching pressure is reduced. At the same time, the microwave power was also lowered and the second stage etching was performed.
The description will be made with reference to FIG.

Example 1 up to the formation of the intermediate layer pattern 4a
Therefore, the description is omitted. The substrate to be etched in FIG. 1B was set in a magnetic field microwave etching apparatus, and as an example, the lower resist layer 3 was etched under the following conditions. O ₂ 40 sccm HCl 10 sccm Gas pressure 2.0 Pa Microwave power 900 W (2.45 GHz) RF bias power 200 W (2 MHz) Substrate temperature Room temperature

In the above etching process, O^*By isotropic
Oxidation reaction is H⁺, Cl⁺And O ⁺Reed to ions such as
While the etching proceeds, the etching reaction
Product CCl_xBecomes a plasma polymer and forms a sidewall protective film
Contributes to success. As a result, as shown in FIG.
Lower resist pattern with anisotropic shape is formed halfway
Was done.

In the first etching step, the upper resist pattern 5 is simultaneously etched off, exposing the intermediate layer pattern 4a. However, at this stage, the remaining portion 3b of the lower resist layer still exists.

Therefore, the etching conditions are switched as follows, for example, and the remaining portion 3b of the lower resist layer is etched. O ₂ 40 sccm HCl 10 sccm Gas pressure 1.0 Pa Microwave power 450 W (2.45 GHz) RF bias power 200 W (2 MHz) Substrate temperature Room temperature In the second etching step, the upper resist pattern 5 is etched off. From the point of time, the amount of reaction product CCl _x decreased, and the amount of O ^* , which became relatively excessive, was reduced by lowering the microwave power. ⁺ , Cl ⁺ and O
Due to the rectilinearity of ions such as ⁺ , a good anisotropic shape was achieved without causing undercut in the lower resist pattern 3a as shown in FIG. 1 (d).

Embodiment 3 In this embodiment, when the lower resist layer is similarly etched by using a mixed gas of O ₂ and HBr, the etching is divided into two steps, and after the upper resist pattern is etched off, Ar gas is supplied. This is an example in which the substrate bias is increased at the same time as the addition, and the second stage etching is performed.
This will be described with reference to FIG.

Example 1 up to the formation of the intermediate layer pattern 4a
Therefore, the description is omitted. The substrate to be etched in FIG. 1B was set in a magnetic field microwave etching apparatus, and as an example, the lower resist layer 3 was etched under the following conditions. O ₂ 40 sccm HBr 10 sccm Gas pressure 2.0 Pa Microwave power 900 W (2.45 GHz) RF bias power 200 W (2 MHz) Substrate temperature Room temperature

In the above etching process, O^*By isotropic
Oxidation reaction is H⁺, Br⁺And O ⁺Reed to ions such as
While the etching proceeds, the etching reaction
Product CBr_xIs a side wall protective film as a plasma polymer
Contributes to success. As a result, as shown in FIG.
Lower resist pattern with anisotropic shape is formed halfway
Was done.

Therefore, the etching conditions are switched as follows as an example, and the remaining portion 3b of the lower resist layer is etched. O ₂ 40 sccm HBr 10 sccm Ar 90 sccm Gas pressure 2.0 Pa Microwave power 900 W (2.45 GHz) RF bias power 300 W (2 MHz) Substrate temperature Room temperature In the second etching step, the upper resist pattern 5 is formed. Although the amount of the reaction product CCl _x that contributes to the formation of the sidewall protective film 6 decreases from the time of the etching off, the unreacted O ^* is added by adding Ar as a diluent gas ^.
Was prevented from being present in excess. In addition, due to the increase in the RF bias power, the ion incident intensity of H ⁺ , Br ^+, O ^{+, and the} like was increased, and Ar ⁺ was added thereto, and etching by ion assist proceeded. Due to these synergistic effects, as shown in FIG. 1D, a good anisotropic shape was achieved without undercutting of the lower resist pattern 3a.

In particular, in this embodiment, by using a Br-based chemical species having a large atomic radius and a low reactivity as compared with Cl, the selectivity with respect to the intermediate layer pattern 4a and the layer with respect to the Al—Si—Cu base material layer 2 is increased. The effect of improving was also seen.

The timing of switching to the second etching step in each of the above-mentioned embodiments is based on the fact that the amount of CO ₂ gas produced as a reaction product decreases after the upper resist pattern is etched off. Then 4
It may be set at the time when the emission spectrum intensity of CO ^* at 83.5 nm starts to decrease.

Although the present invention has been described with reference to the three embodiments, the present invention is not limited to these embodiments.

For example, in the above embodiment, the time point at which the process conditions are switched to the second etching is after the upper resist pattern 5 has been etched off. Absent. According to the basic principle of the present invention, if the switching timing is set near the upper resist pattern being etched off, the effect of preventing the undercut of the lower resist can be sufficiently obtained.

In the above embodiment, Cl ₂ , HCl and HBr were used as the halogen-based gas, but other gases contributing to the formation of the sidewall protective film, such as BCl ₃ and CC
Gases containing halogen atoms such as l ₄ , SiCl ₄ , Br ₂ , BBr ₃ , and HI can be widely used.

The intermediate layer is made of SiO using SOG._TwoSystem material
Used, but Si_ThreeN_FourSystem, Al_TwoO _ThreeSystem, a-Si and each
It is possible to use an inorganic thin film such as a seed metal.
The film formation method also uses sputtering, vapor deposition, various CVD, etc.
be able to.

As the organic material layer on the base material layer, a novolak-based positive photoresist is used in each of the above-described embodiments, but other various resist materials can be used. The present organic material layer is not required to be photosensitive because it is sufficient to flatten the stepped base, and various organic materials such as polyimide can be used.

Further, the configuration of the substrate to be etched, the etching conditions, the etching apparatus, and the like can be appropriately changed. Other etching gas compositions include N ₂ , H ₂ , CO, CO
_2, NO _x systems may be added SO _x based gas or the like.

In addition, without being limited to the above-described embodiment, the effects of the present invention can be obtained by appropriately introducing a second etching having a function of preventing an undercut of the lower resist pattern after etching off the upper resist pattern. Needless to say.

[0060]

As is apparent from the above description, in the present invention, in the etching of the organic material layer such as the lower resist in the three-layer resist process, the function of the side wall protective film deteriorates due to the decrease in the reaction products after the etch-off of the upper resist. This effectively prevents undercut of the lower resist pattern due to the above, and realizes a dry etching method of a multilayer resist excellent in an anisotropic shape having no dimensional conversion difference.

Further, according to the present invention, a dry etching method of a clean multi-layer resist free from particle contamination while preventing re-adhesion to the side wall of the lower resist pattern due to sputtering of the base material layer and preventing pattern shift can be performed.

Further, according to the present invention, while ensuring a practical etching rate, a dry etching method of a clean multilayer resist which eliminates undercut and dimensional conversion difference of a lower resist pattern and has no under-layer spatter can be achieved.

With the above effects, for example, the practicality of the three-layer resist process can be improved, and in a manufacturing process of a semiconductor device having a multilayer wiring structure based on a fine design rule, which requires high integration and high reliability. It is valid. The present invention is not limited to the above semiconductor device,
OEI that needs to be patterned on a high step substrate etc.
C, a bubble domain storage device, and even a patterning of a thin-film magnetic head coil and the like are highly effective.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating Examples 1, 2 and 3 to which the present invention is applied in the order of steps, and FIG. 1A shows a lower resist layer on an Al—Si—Cu alloy base material layer having a step. , A state in which an intermediate layer and an upper layer resist pattern are sequentially formed, (b) a state in which an intermediate layer pattern is formed,
(C) shows a state in which the underlying resist pattern is formed halfway by performing the first etching step on the lower resist layer using the upper resist pattern and the intermediate layer pattern as a mask, and the upper resist pattern has been etched away. State (d) shows a state in which a second etching process is performed on the remaining portion of the lower resist using the intermediate layer pattern as a mask to complete the lower resist pattern.

2A and 2B are schematic cross-sectional views illustrating a conventional three-layer resist technique in the order of steps, and FIG. 2A shows a lower resist layer, an intermediate layer, and an upper resist pattern sequentially formed on a base material layer having a step. (B) shows a state in which an intermediate layer pattern is formed, and (c) shows a state in which the lower resist pattern is completed by etching the lower resist layer using the upper resist pattern and the intermediate pattern as a mask.

FIG. 3 is a schematic cross-sectional view showing a problem of the conventional multilayer resist technology, in which a lower resist pattern side wall above a step is provided with:
This is a state in which the sputter-redeposited substance layer of the base material layer is formed.

FIGS. 4A and 4B are schematic cross-sectional views illustrating the problems of the conventional multilayer resist technology in the order of the steps. FIG. 4A is a diagram in which a lower resist layer is etched using an upper resist pattern and an intermediate layer as a mask, and The state immediately after being turned off, (b) shows a state in which the lower layer resist pattern is completed by etching the remaining portion of the lower layer resist using the intermediate layer pattern as a mask.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Interlayer insulating film 2 Underlayer material layer (Al-Si-Cu alloy layer) 3 Lower resist layer 3a Lower resist pattern 3b Remaining part of lower resist layer 4 Interlayer 4a Interlayer pattern 5 Upper resist pattern 6 Side wall protective film

Claims (3)

(57) [Claims] An organic material layer, an intermediate layer and an upper resist pattern are sequentially formed on a base material layer, the intermediate layer is patterned using the upper resist pattern as a mask, and then the organic layer is patterned using at least the intermediate layer pattern as a mask. In the method of dry etching a multilayer resist for patterning a material layer, the patterning of the organic material layer is performed by a first etching step until the upper resist pattern is etched off, and after the upper resist pattern is etched off.
A second etching step, and oxygen gas and
A mixed gas containing a halogen-based gas is used as an etching gas,
Independent control of plasma generation power and substrate bias power
The second etching step is performed using a plasma etching apparatus capable of performing the first etching process.
Lower the etching pressure than
A dry etching method characterized in that the formation power is increased . 2. An organic material layer, an intermediate layer and an upper resist pattern are sequentially formed on a base material layer, the intermediate layer is patterned using the upper resist pattern as a mask, and then the organic layer is patterned using at least the intermediate layer pattern as a mask. In the method of dry etching a multilayer resist for patterning a material layer, the patterning of the organic material layer is performed by a first etching step until the upper resist pattern is etched off, and after the upper resist pattern is etched off.
A second etching step, and oxygen gas and
A mixed gas containing a halogen-based gas is used as an etching gas,
Independent control of plasma generation power and substrate bias power
The second etching step is performed using an etching gas
A dry etching method characterized in that the dry etching method is performed by adding an etching gas. 3. An organic material layer, an intermediate layer, and an upper resist pattern are sequentially formed on a base material layer, and the intermediate layer is patterned using the upper resist pattern as a mask. In the method of dry etching a multilayer resist for patterning a material layer, the patterning of the organic material layer is performed by a first etching step until the upper resist pattern is etched off, and after the upper resist pattern is etched off.
A second etching step, and oxygen gas and
A mixed gas containing a halogen-based gas is used as an etching gas,
Independent control of plasma generation power and substrate bias power
The second etching step is performed using a plasma etching apparatus capable of performing the first etching process.
A dry etching method characterized in that the method is performed by increasing the substrate bias power more than the above .