JP2009059855A - Dry etching method and method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dry etching method which can prevent side etching of resist from occurring and can process a base film into a desired shape in an excellent way, and to provide a method for manufacturing a semiconductor device using the same. <P>SOLUTION: The dry etching method etches a base film 110 using a multilayer resist on which a lower layer resist 120, an interlayer 130, and an upper layer resist 140 are laminated in order from the bottom thereof, wherein the method includes: a step (a) of etching the lower layer resist 120 using an etching gas containing a primary gas and a secondary gas with the upper layer resist 140 and the interlayer 130 used as a mask after the multilayer resist has been formed on the base film 110; and a step (b) of etching the base film 110 using an etching gas containing the secondary gas after the step (a) with the lower layer resist 120 used as a mask. The secondary gas is a gas for etching the base film 110. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dry etching method using a multilayer resist and a semiconductor device manufacturing method using the same.

  In recent years, with the miniaturization of semiconductor devices, the resist used for pattern formation has been made thinner. For example, in the 65 nm design rule process, patterning is performed by exposing and developing using a resist made of ArF (argon fluoride) with a film thickness of about 200 nm. However, in the 45 nm design rule process, it is necessary to further reduce the resist to be used to a film thickness of about 150 nm.

  For this reason, it is difficult to prepare a resist having a desired selectivity, particularly in a process of processing a base film by dry etching using a patterned resist as a mask. Therefore, in place of the conventional dry etching method using a single layer resist, a multilayer resist process in which etching is performed using a multilayer resist is being studied.

  A pattern forming method using a conventional multilayer resist process will be described with reference to FIG. 5A to 5D are sectional views showing a conventional dry etching method using a multilayer resist.

  First, as shown in FIG. 5A, after forming a base film (processed film) 510 to be patterned on the semiconductor substrate 500, a lower layer resist 520, an intermediate layer 530, and an upper layer resist 540 are formed on the base film 510. Are sequentially formed. Subsequently, the upper resist 540 is patterned by exposure and development.

  Next, as shown in FIG. 5B, the pattern is transferred to the intermediate layer 530 by processing the intermediate layer 530 by dry etching using the upper layer resist 540 as a mask.

  Next, as shown in FIG. 5C, the pattern is transferred to the lower layer resist 520 by processing the lower layer resist 520 by dry etching using the intermediate layer 530 as a mask.

  Finally, as shown in FIG. 5D, a desired pattern is formed on the base film 510 by processing the base film (processed film) 510 by dry etching using the lower layer resist 520 as a mask.

  On the other hand, in general, when processing using dry etching, in-plane distribution and variation of the etching rate are taken into consideration, and the desired processing shape can be stably obtained even if there is a step in the underlying substrate. A certain amount of over-etching is performed so that

  However, as shown in FIG. 5C, in the conventional dry etching method, an etchant such as an oxygen radical becomes excessive when the lower layer resist 520 is processed, and side etching occurs in the lower layer resist 520 due to the excessive etchant. There was a problem that.

  If side etching occurs in the lower layer resist 520, there is a possibility that problems such as deterioration in dimensional accuracy when the base film 510 provided under the lower layer resist 520 is processed or a desired dimension cannot be obtained. The reason why this side etching occurs is that when the lower layer resist 520 is etched, the selection ratio of the base film 510 and the intermediate layer 530 to the lower layer resist 520 is large, and the base film 510 and the intermediate layer 530 are difficult to be etched. Specifically, the etchant becomes excessive as the etching of the upper layer resist 540 and the lower layer resist 520 is finished due to the difference in the selection ratio and the exposed areas of the base film 510 and the intermediate layer 530 are increased. Then, side etching of the lower resist 520 proceeds due to this excessive etchant.

As a method for solving the above-described problem, for example, a method of forming a protective film on the side wall of the lower resist 520 by adding a gas when etching the lower resist 520 has been devised (for example, see Patent Document 1). ). According to this method, since the lower resist 520 is protected by the protective film, the progress of the side etching can be suppressed.
Japanese Patent Laid-Open No. 5-283375

  However, since the etchant becomes excessive at the time of overetching, in the conventional solution described above, when a protective film is formed on the side wall of the lower resist, an excessive protective film is formed before the overetching process. As a result, the lower layer resist has a forward taper shape and the vertical shape of the resist pattern cannot be maintained.

In view of the above-described problems, the present invention provides a dry etching method using a multilayer resist, in which the occurrence of resist side etching is suppressed, and a dry etching method capable of satisfactorily processing a base film into a desired shape, and An object of the present invention is to provide a method of manufacturing a semiconductor device using the same.

  In order to solve the above problems, a first dry etching method of the present invention is a dry etching method in which a base film is etched using a multilayer resist in which a lower layer resist, an intermediate layer, and an upper layer resist are sequentially laminated from the bottom. Then, after forming the multilayer resist on the base film, using the upper resist and the intermediate layer as a mask, an etching gas containing a first gas and a second gas for etching the base film is used. And (b) etching the underlying film using the etching gas containing the second gas using the underlying resist as a mask after the step (a). ).

  According to the first method, in addition to the first gas for etching the lower layer resist in the step (a), the second gas for etching the lower layer resist is added, thereby etching the lower layer resist. Even if the process is completed, the base film is etched by the second gas. Thereby, it is possible to prevent the side etching of the lower resist from occurring due to an excessive etchant. Therefore, by using the first dry etching method of the present invention, the base film can be processed into a desired shape with high accuracy without causing side etching of the resist.

  The second dry etching method of the present invention is a dry etching method in which a base film is etched using a multilayer resist in which a lower layer resist, an intermediate layer, and an upper layer resist are laminated in order from the bottom. After the multilayer resist is formed thereon, the intermediate layer is etched using an etching gas containing a first gas using the upper layer resist as a mask, and after the step (a), the intermediate layer is etched. Etching the lower layer resist to a predetermined thickness using an etching gas containing a second gas using the layer as a mask, and after the step (b), using the intermediate layer as a mask, (C) further etching the lower layer resist using an etching gas containing the first gas and the second gas until the base film is exposed; It is provided.

  According to the second method, the lower layer resist is etched in two steps using the steps (b) and (c) in which the etching gases are different from each other. Specifically, in the process (b) that is the first step, only the lower layer resist is etched using the second gas, and then in the process (c) that is the second step, the second gas is intermediate The lower layer resist is completely etched using the first gas for etching the layer. As a result, even if the etching of the lower layer resist is completed in the second step, the etching of the intermediate layer proceeds with the first gas, so that the side etching of the lower layer resist can be prevented from being caused by an excessive etchant. it can. Therefore, according to the second dry etching method of the present invention, it is possible to accurately process the base film into a desired shape without causing side etching of the resist.

  The third dry etching method of the present invention is a dry etching method in which a base film is etched using a multilayer resist in which a lower layer resist, an intermediate layer, and an upper layer resist are sequentially stacked from the bottom. (A) etching the intermediate layer using the upper layer resist as a mask after the multilayer resist is formed thereon; and after the step (a), using the upper layer resist and the intermediate layer as a mask Etching the lower layer resist until the base film is exposed, and removing the upper layer resist and the intermediate layer (b), and in the step (b), until the base film is exposed. The upper resist and the intermediate layer are removed.

  According to the third method, in the step (b), the lower layer resist is etched in consideration of the etching rates of the upper layer resist, the intermediate layer, and the lower layer resist. As a result, due to the difference in etching rate, the intermediate layer and the upper layer resist provided on the lower layer resist are completely removed when the lower layer resist is etched to expose the base film. Therefore, even after the lower layer resist is etched into a desired shape, the etching of the lower layer resist continues, so that the etchant can be prevented from becoming excessive. Accordingly, also in the third dry etching method of the present invention, the occurrence of side etching of the resist can be suppressed and the base film can be processed satisfactorily in the same manner as described above.

  The fourth dry etching method of the present invention is a dry etching method in which a base film is etched using a multilayer resist in which a lower layer resist, an intermediate layer, and an upper layer resist are sequentially stacked from the bottom. A step (a) of sequentially forming a protective film, the lower layer resist, the intermediate layer, and the upper layer resist on the upper layer, etching the intermediate layer using the upper layer resist as a mask, and then masking the upper layer resist and the intermediate layer And (b) etching the lower resist until the protective film is exposed while adding an etching gas, and in the step (b), the exposed protective film absorbs or consumes the etching gas. It is characterized by doing.

  According to the fourth method, a protective film is provided between the lower layer resist and the base film, so that after the lower layer resist is processed into a desired shape until the protective film is exposed in step (b), it is added. Etching gas is consumed or adsorbed on the exposed protective film and does not act on the underlying resist. As a result, the etchant can be prevented from becoming excessive after the etching of the lower layer resist is completed, and the side etching of the lower layer resist can be suppressed.

  Moreover, the manufacturing method of the semiconductor device of this invention patterns a base film using the above-mentioned 1st-4th dry etching method of this invention. If this method is used, a patterned gate electrode can be obtained with good accuracy if patterning is performed using, for example, a gate electrode formation film as a base film. Therefore, according to the method for manufacturing a semiconductor device of the present invention, a semiconductor element or the like can be accurately manufactured at a desired position even when miniaturized, and a highly reliable semiconductor device can be realized.

  According to the dry etching method and the semiconductor device manufacturing method of the present invention, the occurrence of side etching of the resist can be suppressed, and a base film processed to have a desired dimension with high accuracy can be obtained.

(First embodiment)
Hereinafter, a dry etching method according to a first embodiment of the present invention will be described with reference to FIGS. 1A to 1E are cross-sectional views illustrating a dry etching method according to this embodiment.

  First, as shown in FIG. 1A, a base film (processed film) 110 made of, for example, polysilicon is deposited on a semiconductor substrate 100 with a film thickness of, for example, 140 nm. Next, a lower layer resist 120 made of a carbon-containing resist or the like is formed on the base film 110 by coating, for example, and then a silicon-containing resist or the like is formed on the lower layer resist 120 by a thickness of, for example, 80 nm. The intermediate layer 130 is formed by coating. Next, an upper resist 140 having a film thickness of, for example, 150 nm and made of a polyacrylic acid resin material or the like is applied on the intermediate layer 130. Thereby, a multilayer resist composed of the lower layer resist 120, the intermediate layer 130, and the upper layer resist 140 can be formed. Subsequently, the upper resist 140 is patterned by exposure and development.

Next, as shown in FIG. 1B, the semiconductor substrate 100 is placed in an etching apparatus (not shown) using UHF-ECR (Ultra High Frequency Electron Cyclotron Resonance) plasma as a plasma source, and an upper resist layer is formed. The intermediate layer 130 is etched using fluorine gas such as CF ₄ using 140 as a mask. At this time, the upper surface of the lower resist 120 may be removed by overetching.

Next, as shown in FIG. 1C, the lower layer resist 120 is processed using the upper layer resist 140 and the intermediate layer 130 as a mask. At this time, as the etching gas 150, a mixed gas of N ₂ and CO ₂ (first gas) to which HBr (second gas) is added is used. HBr (second gas) is a gas for etching the base film 110. As specific etching conditions, for example, the pressure is 0.8 Pa, the plasma generation power (UHF) is 800 W, the bias power is 40 W, and the flow rate is HBr / N ₂ / CO ₂ = 20/70/100 [mL / min], the coil current is HBr / N ₂ / CO ₂ = 4/0/7 [A], and the stage temperature is center / periphery = 35/20 [° C.].

Here, the etching gas 150 used in this step is an etching gas (second gas) for the base film 110 such as HBr in addition to the etching gas (first gas) for the lower layer resist 120 such as N ₂ and CO _2. Is included. Thereby, even when the etching of the lower layer resist 120 is completed, the etching of the base film 110 proceeds because the etching gas 150 contains HBr. Therefore, it is possible to prevent the etchant from becoming excessive, and side etching of the lower layer resist 120 due to the excessive etchant can be prevented. In this step, after etching the lower layer resist 120 until the base film 110 is exposed, the upper surface of the exposed base film 110 may be removed by overetching.

Subsequently, as shown in FIG. 1D, the base film 110 is etched using, for example, a mixed gas of HBr (second gas) and Cl ₂ using the intermediate layer 130 and the lower layer resist 120 as a mask. Thereafter, as shown in FIG. 1E, the lower layer resist 120 is removed by ashing. By the above method, the base film 110 made of a silicon film can be processed into a desired shape. Even if the upper surface of the base film 110 is removed in the step shown in FIG. 1C, there is no problem because the base film 110 is finally patterned in this step.

  The feature of the dry etching method of this embodiment is that HBr, which is an etching gas for the underlying film 110, is added in addition to the etching gas for the lower layer resist 120 in the step shown in FIG. Thereby, even if the etching of the lower layer resist 120 is completed, the base film 110 is etched by HBr, so that side etching of the lower layer resist 120 can be prevented from occurring due to an excessive etchant. Therefore, according to the dry etching method of the present embodiment, it is possible to accurately process the base film into a desired shape without causing side etching of the resist.

  Further, if the dry etching method of the present embodiment is used, side etching of the lower layer resist 120 can be prevented only by changing the etching gas 150 in the step shown in FIG. 1C, compared with the conventional dry etching method. The base film can be processed relatively easily without using a complicated process.

  In the dry etching method of this embodiment, when a silicon film is used as the base film 110, the etching gas (second gas) for the base film 110 used in FIGS. 1B and 1C is chlorine gas or A bromine gas, or a gas containing chlorine or a gas containing bromine is preferable. In the case where an insulating film is used as the base film 110, the second gas is preferably a gas containing fluorine. On the other hand, when a metal film is used as the base film 110, the second gas is preferably a gas containing a chlorine element or a gas containing a bromine element.

(Second Embodiment)
Hereinafter, a dry etching method according to the second embodiment of the present invention will be described with reference to FIGS. 2A to 2E are cross-sectional views showing the dry etching method of this embodiment.

  First, as shown in FIG. 2A, a base film (film to be processed) 210 made of, for example, a nitride film is deposited on the semiconductor substrate 200 with a film thickness of, for example, 130 nm. Next, a lower layer resist 220 made of a carbon-containing resist or the like is formed by coating on the base film 210 with a film thickness of, for example, 250 nm, and then an SOG containing Si, for example, with a film thickness of, for example, 80 nm on the lower layer resist 220. An intermediate layer 230 made of a (Spin On Glass) film is formed by coating. Next, an upper resist 240 having a film thickness of, for example, 150 nm and made of a polyacrylic resin material or the like is applied on the intermediate layer 230. Thereby, a multilayer resist composed of the lower layer resist 220, the intermediate layer 230, and the upper layer resist 240 can be formed. Subsequently, the upper resist 240 is patterned by exposure and development.

Next, as shown in FIG. 2B, the semiconductor substrate 200 is placed in a two-frequency excitation capacitively coupled plasma etching apparatus (not shown), and the upper layer resist 240 is used as a mask, for example, CF ₄ and CHF _3. The intermediate layer 230 is etched using the mixed gas (first gas). Next, the lower layer resist 220 is processed using the upper layer resist 240 and the intermediate layer 230 as a mask. At this time, first, etching is performed using, for example, a mixed gas of CO and O ₂ (second gas) while observing with a film thickness monitor or the like until the film thickness of the lower resist 220 reaches about 20 nm.

Subsequently, as illustrated in FIG. 2C, the base film 210 is exposed using a mixed gas of CO, O ₂ , and CF ₄ in which CF ₄ is added to the second gas as the etching gas 250. Until that, the remaining lower layer resist 220 is etched. CF ₄ is a gas for etching the intermediate layer 230. As specific etching conditions, for example, the pressure is 0.8 Pa, the upper electrode power is 900 W, the lower electrode power is 600 W, the flow rate is CO / O ₂ / CF ₄ = 100/50/50 [mL / min], the lower part The temperature of the electrode is set to center / periphery = 55/45 [° C.]. When etching is performed under these conditions, not only the remaining lower layer resist 220 but also the intermediate layer 230 are etched together. Therefore, even when the etching of the lower layer resist 220 is completed, the etching of the intermediate layer 230 proceeds, so that the etchant does not become excessive, and the side etching of the lower layer resist 220 can be prevented from occurring. When the lower layer resist 220 was etched using only the first gas without adding CF ₄ , side etching of about 15 nm occurred in the lower layer resist 220. However, when the dry etching method of this embodiment is used, The side etching amount of the lower layer resist 220 was almost 0 nm, and the side etching amount could be improved.

Subsequently, as shown in FIG. 2D, the base film 210 is etched using, for example, a mixed gas of CF ₄ and CHF ₃ using the intermediate layer 230 and the lower layer resist 220 as a mask. Thereafter, as shown in FIG. 2E, the lower layer resist 220 is removed by ashing. By the above method, the base film 210 made of a nitride film can be processed into a desired shape.

A feature of the dry etching method of the present embodiment is that the lower layer resist 220 is etched using two steps in which etching gases are different from each other in the steps shown in FIGS. According to this method, after etching only the lower layer resist 220 using the second gas in the first step, a gas for etching the intermediate layer 230 is added to the second gas in the second step. The lower layer resist 220 is completely etched using the etching gas 250. Thus, even if the etching of the lower layer resist 220 is completed in the second step, the etching of the intermediate layer 230 proceeds by CF ₄ , and therefore, side etching of the lower layer resist 220 is prevented from being generated by an excessive etchant. Can do. Therefore, according to the dry etching method of the present embodiment, it is possible to accurately process the base film into a desired shape without causing side etching of the resist.

  In the dry etching method of the present embodiment, when a film containing silicon is used as the intermediate layer 230, the gas (first gas) for etching the intermediate layer 230 in FIGS. 2B and 2C is A gas containing a fluorine element or a gas containing a chlorine element is preferable.

(Third embodiment)
Hereinafter, a dry etching method according to the third embodiment of the present invention will be described with reference to FIGS. 3A to 3C are cross-sectional views illustrating the dry etching method of the present embodiment.

  First, as shown in FIG. 3A, a base film (film to be processed) 310 made of, for example, a TEOS (Tetraethoxysilane) film is deposited on a semiconductor substrate 300 to a thickness of, for example, 130 nm. Next, a lower layer resist 320 made of a carbon-containing resist or the like is formed on the base film 310 with a film thickness of 400 nm, for example, and then formed on the lower layer resist 320 with a film thickness of 70 nm or the like. The intermediate layer 330 is formed by coating. Next, an upper resist 340 having a film thickness of, for example, 150 nm and made of a polyacrylic resin material or the like is applied on the intermediate layer 330. Thereby, a multilayer resist composed of the lower layer resist 320, the intermediate layer 330, and the upper layer resist 340 can be formed. Subsequently, the upper layer resist 340 is patterned by exposure and development.

Next, as shown in FIG. 3B, the semiconductor substrate 300 is placed in an etching apparatus (not shown) using UHF-ECR plasma as a plasma source, and the upper layer resist 340 is used as a mask, for example, CF ₄ and The intermediate layer 330 is etched using a mixed gas of CHF ₃ . At this time, the upper layer resist 340 is also etched together with the intermediate layer 330, and the film thickness of the upper layer resist 340 is about 50 nm.

Next, as shown in FIG. 3C, the lower resist 320 is etched using the upper resist 340 and the intermediate layer 330 as a mask. As specific etching conditions, for example, the pressure is 1.5 Pa, the plasma generation power (UHF) is 400 W, the bias power is 100 W, and the flow rate is Ar / N ₂ / CO ₂ = 200/200/100 [mL / min. The stage temperature is 20 ° C. Under these conditions, the etching rates of the upper layer resist 340, the intermediate layer 330, and the lower layer resist 320 are 130 nm / min, 20 nm / min, and 100 nm / min, respectively. Therefore, in this step, the intermediate layer 330 and the remaining upper layer resist 340 are removed within a time (4 min) required to etch the lower layer resist 320 until the base film 310 is exposed, and the lower layer resist 320 is completely exposed. It will be in the state. Here, if the lower layer resist 320 has a sufficient film thickness and has a pattern shape for processing the base film 310, there is no problem even if the intermediate layer 330 is removed.

Next, using the lower layer resist 320 as a mask, the base film 310 is etched using a gas containing a fluorocarbon such as CF ₄ . Thereafter, the lower layer resist 320 is removed by ashing. By the above method, the base film 310 made of a nitride film can be processed into a desired shape.

  The feature of the dry etching method of this embodiment is that the lower resist 320 is etched in consideration of the etching rates of the upper resist 340, the intermediate layer 330, and the lower resist 320 in the step shown in FIG. is there. According to this method, due to the difference in etching rate, the intermediate layer 330 and the upper layer resist 340 provided on the lower layer resist 320 are completely removed when the lower layer resist 320 is etched to expose the base film 310. ing. Thereby, even after the lower layer resist 320 is etched into a desired shape, the etching of the lower layer resist 320 proceeds continuously, so that the etchant can be prevented from becoming excessive. In addition, unlike the conventional method, since films having different selectivity are not formed on the lower resist 320, it is possible to more reliably prevent the side surfaces of the lower resist 320 from being etched. Therefore, if the dry etching method of this embodiment is used, side etching can be prevented from occurring due to excessive etchant, and the base film can be processed into a desired shape with high accuracy.

(Fourth embodiment)
Hereinafter, a dry etching method according to the fourth embodiment of the present invention will be described with reference to FIGS. 4A to 4D are cross-sectional views illustrating the dry etching method of the present embodiment.

  First, as shown in FIG. 4A, a base film (film to be processed) 410 used as an interlayer insulating film between wiring layers formed in a semiconductor device, for example, is deposited on the semiconductor substrate 400 to a film thickness of 400 nm, for example. . Next, a protective film 420 made of, for example, TiN is deposited on the base film 410 to a thickness of 20 nm. Thereafter, a lower layer resist 430 made of a carbon-containing resist or the like is formed on the protective film 420 with a film thickness of 200 nm, for example, by coating, and then an intermediate layer made of a silicon-containing resist or the like with a thickness of 80 nm, for example, Layer 440 is deposited by coating. Next, an upper resist 450 made of, for example, a polyacrylic resin material having a thickness of 150 nm is applied on the intermediate layer 440. Thereby, a multilayer resist composed of the lower layer resist 430, the intermediate layer 440, and the upper layer resist 450 can be formed. Subsequently, the upper resist 450 is patterned by performing exposure and development processes.

Next, as shown in FIG. 4B, the semiconductor substrate 400 is placed in an etching apparatus (not shown) using UHF-ECR (Ultra High Frequency Electron Cyclotron Resonance) plasma as a plasma source, and an upper resist layer is formed. The intermediate layer 440 is etched using, for example, CF ₄ gas using 450 as a mask. At this time, the upper surface of the lower resist 430 may be removed by overetching.

Next, the lower layer resist 430 is processed using the upper layer resist 450 and the intermediate layer 440 as a mask. At this time, for example, a mixed gas of O ₂ and Ar in which the etchant becomes an oxygen radical is used as the etching gas 460. Accordingly, since the protective film 420 made of TiN has an action of gettering oxygen radicals, if the lower resist 430 is etched until the upper surface of the protective film 420 is exposed, the oxygen radicals are adsorbed on the protective film 420, resulting in excess. Generation of oxygen radicals can be suppressed. Therefore, side etching of the lower layer resist 430 due to an excessive etchant can be prevented.

  Subsequently, as shown in FIG. 4C, the protective film 420 and the base film 410 are etched using a gas containing chlorine and a gas containing fluorine, respectively, using the intermediate layer 440 and the lower layer resist 430 as a mask. At this time, the intermediate layer 440 is removed together with the protective film 420 and the base film 410 by etching.

  Next, as shown in FIG. 4D, after the lower layer resist 430 is removed by, for example, ashing, it is made of TiN by a cleaning process using, for example, APM (Ammonia Peroxide Mixture / ammonia-hydrogen peroxide mixture). The protective film 420 is removed. By the above method, the base film 410 for the wiring interlayer film can be processed into a predetermined shape.

  A feature of the dry etching method of the present embodiment is that a protective film 420 that adsorbs or consumes the etching gas of the lower layer resist 430 is provided between the lower layer resist 430 and the base film 410. Thus, after the etching of the lower resist 430 is completed in the step shown in FIG. 4B, the added etchant is consumed or adsorbed by the protective film 420, so that it does not act on the lower resist 430 as an etchant. As a result, the etchant can be prevented from becoming excessive after the etching of the lower layer resist 430 is completed, and the side etching of the lower layer resist 430 can be suppressed. Therefore, if the dry etching method of this embodiment is used, even if it is miniaturized, side etching of the multilayer resist is prevented, and the base film can be processed into a desired shape with high accuracy.

  In the dry etching method of the present embodiment, TiN is used as the protective film 420, but the present invention is not limited to this. When oxygen radicals are used as the etchant for the lower layer resist 430, the protective film 420 may be titanium or a compound containing titanium, or a compound containing carbon such as a carbon nanotube. Further, it may be a polymer metal complex such as a porphyrin complex or a compound containing a polymer metal complex. Since these materials have an effect of adsorbing oxygen radicals, the same effect as described above can be obtained.

  The etchant for the lower layer resist 430 is not limited to oxygen radicals, and a gas such as ammonia gas may be used. In this case, the same effect as described above can be obtained by using, as the protective film 420, a material having an action such as consumption or adsorption of the etchant according to the etchant to be used.

  Further, in the dry etching method according to the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment of the present invention, for example, patterning is performed using a gate electrode forming film as a base film. A gate electrode processed with good accuracy can be obtained. Therefore, by using the dry etching method of the present invention, a semiconductor device provided with a gate electrode or the like can be manufactured with high precision even if miniaturized.

  Further, when an interlayer insulating film is used as the base film, a contact hole or the like can be formed at a desired position with high accuracy.

  The dry etching method of the present invention and the method of manufacturing a semiconductor device using the same are useful for miniaturization of a semiconductor device.

(A)-(e) is sectional drawing which shows the dry etching method which concerns on the 1st Embodiment of this invention. (A)-(e) is sectional drawing which shows the dry etching method which concerns on the 2nd Embodiment of this invention. (A)-(c) is sectional drawing which shows the dry etching method which concerns on the 3rd Embodiment of this invention. (A)-(d) is sectional drawing which shows the dry etching method which concerns on the 4th Embodiment of this invention. (A)-(d) is sectional drawing which shows the dry etching method using the conventional multilayer resist.

Explanation of symbols

100 Semiconductor substrate
110 Underlayer
120 Lower resist
130 Middle layer
140 Upper resist
150 Etching gas
200 Semiconductor substrate
210 Underlayer
220 Underlayer resist
230 Middle layer
240 Upper layer resist
250 Etching gas
300 Semiconductor substrate
310 Underlayer
320 Underlayer resist
330 Middle layer
340 Upper resist
400 Semiconductor substrate
410 Underlayer
420 Protective film
430 Underlayer resist
440 Middle layer
450 Upper layer resist
460 Etching gas

Claims (15)

A dry etching method for etching a base film using a multilayer resist in which a lower layer resist, an intermediate layer, and an upper layer resist are sequentially laminated from the bottom,
After forming the multi-layer resist on the base film, using the upper resist and the intermediate layer as a mask, a first gas and an etching gas containing a second gas for etching the base film are used. Etching the lower layer resist (a);
A dry etching method comprising, after the step (a), a step (b) of etching the base film using an etching gas containing the second gas using the lower layer resist as a mask.   The dry etching method according to claim 1, wherein in the step (a), a part of the base film is etched together with the lower layer resist. The base film is made of an insulating film,
The dry etching method according to claim 1, wherein the second gas is a gas containing fluorine. The base film is made of a silicon film,
3. The dry etching method according to claim 1, wherein the second gas is chlorine gas or bromine gas, or gas containing chlorine element or gas containing bromine element. The base film is made of a metal film,
The dry etching method according to claim 1, wherein the second gas is a gas containing a chlorine element or a gas containing a bromine element. A dry etching method for etching a base film using a multilayer resist in which a lower layer resist, an intermediate layer, and an upper layer resist are sequentially laminated from the bottom,
(A) etching the intermediate layer using an etching gas containing a first gas using the upper layer resist as a mask after forming the multilayer resist on the underlayer;
After the step (a), using the intermediate layer as a mask, etching the lower layer resist to a predetermined film thickness using an etching gas containing a second gas;
After the step (b), using the intermediate layer as a mask, using the etching gas containing the first gas and the second gas, further etching the lower layer resist until the base film is exposed ( and c) a dry etching method.   The dry etching method according to claim 6, wherein in the step (c), the intermediate layer is etched together with the lower layer resist. The intermediate layer is made of a film containing silicon,
The dry etching method according to claim 6 or 7, wherein the first gas is a gas containing a fluorine element or a gas containing a chlorine element. A dry etching method for etching a base film using a multilayer resist in which a lower layer resist, an intermediate layer, and an upper layer resist are sequentially laminated from the bottom,
(A) etching the intermediate layer using the upper layer resist as a mask after forming the multilayer resist on the base film;
After the step (a), using the upper layer resist and the intermediate layer as a mask, etching the lower layer resist until the base film is exposed, and removing the upper layer resist and the intermediate layer (b) With
A dry etching method in which, in the step (b), the upper layer resist and the intermediate layer are removed before the base film is exposed.   The dry etching method according to claim 9, wherein in the step (a), the upper portion of the upper layer resist is removed together with the intermediate layer. A dry etching method for etching a base film using a multilayer resist in which a lower layer resist, an intermediate layer, and an upper layer resist are sequentially laminated from the bottom,
A step (a) of sequentially forming a protective film, the lower layer resist, the intermediate layer, and the upper layer resist on the base film;
(B) etching the intermediate layer using the upper layer resist as a mask and then etching the lower layer resist using the upper layer resist and the intermediate layer as a mask until the protective film is exposed while adding an etching gas. Prepared,
In the step (b), the exposed protective film adsorbs or consumes the etching gas. The etching gas is a gas containing oxygen radicals,
The dry etching method according to claim 11, wherein the protective film is made of titanium or a compound containing titanium. The etching gas is a gas containing oxygen radicals,
The protective film is made of a compound containing carbon,
The dry etching method according to claim 11, wherein in the step (b), the protective film adsorbs the etching gas. The etching gas is a gas containing oxygen radicals,
The protective film is made of a polymer metal complex or a compound containing the polymer metal complex,
The dry etching method according to claim 11, wherein in the step (b), the protective film adsorbs the etching gas.   A method for manufacturing a semiconductor device, wherein the base film is patterned using the dry etching method according to claim 1.

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