JP2008118016A - Method for forming organic film pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming patterns in an organic film including favorable copper (Cu) without leaving copper (Cu) residue or unremoved parts of a sidewall protective film. <P>SOLUTION: The method for forming patterns in the organic film including copper (Cu) includes a plasma etching process step for dry etching the organic film 3 which includes copper (Cu) placed on a base film 2 placed on a semiconductor substrate 1 by plasma gas which is a mixture of chlorine (Cl<SB>2</SB>) and oxygen (O<SB>2</SB>) through a resist mask 4, an ashing process step for ashing the organic film 3 by plasma gas which is a mixture of one of methanol (CH<SB>3</SB>OH), ethanol (C<SB>2</SB>H<SB>5</SB>OH) and isopropanol (C<SB>3</SB>H<SB>7</SB>OH) and oxygen (O<SB>2</SB>) and a process for removing the resist mask by an organic solvent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for processing an organic film layer used in a semiconductor manufacturing process, and to a processing method that enables suitable organic film pattern formation.

  In manufacturing a semiconductor device, a base film is formed on a semiconductor substrate, an organic film layer containing copper (Cu) is formed thereon, a photoresist layer is further formed thereon, and then the photoresist layer is patterned. Therefore, it is required to etch the organic film phase using this mask.

  As a method for forming a pattern of an organic film layer, an organic film layer and a resist layer are formed on a semiconductor substrate as a first process, a resist mask is patterned by photolithography as a second process, and a resist mask is used as a third process. A pattern forming method of performing patterning on the organic film layer by the dry etching process performed, processing the resist mask surface by an ashing process as the fourth process, and removing the resist mask with the organic solvent as the fifth process. It is disclosed (for example, see Patent Document 1).

Among them, the etching process for patterning the organic film layer in the third step includes a method of etching with an oxygen (O ₂ ) plasma gas and a method of etching with a plasma gas in which a chlorine-based gas and oxygen (O ₂ ) are mixed. It has been proposed (see, for example, Patent Documents 1 and 2).

As the ashing process in the fourth step, a method of ashing with a plasma gas in which a fluorocarbon-based gas and oxygen (O ₂ ) are mixed has been proposed. Unlike the ashing of the metal film sample, the ashing treatment of the organic film sample ashes not only the resist mask but also the organic film layer when ashing is performed for a long time. For this reason, a method of performing ashing for a short time without removing the resist mask and removing the resist mask with an organic solvent is employed (see, for example, Patent Document 1).

An example of a substrate to be processed used in these methods is shown in FIG. A substrate to be processed is formed on a semiconductor substrate (for example, Si wafer) 1 by forming a base film (a film having a role of an etch stopper for an organic film layer, for example, an organic film layer different from SiO ₂ or an upper layer) 2, A substrate to be processed on which a polyimide or acrylic organic film 3 containing copper (Cu) is formed and a resist mask 4 is further formed thereon is used. In these etching methods, the organic film layer 3 containing copper (Cu) of the substrate to be processed is dry-etched using the resist mask 4 as a mask. In this case, there is a problem that a copper (Cu) residue is generated on the surface of the base film 2 after the organic film layer 3 is etched.

  In the ashing process, if a sidewall protective film adheres to the resist mask surface or the sidewall of the organic film layer 3 in the etching process in the previous step, the sidewall protective film cannot be removed in the ashing process. There is a problem that the remaining removal of the sidewall protective film occurs.

As described above, in the conventional technique, the etching (pattern formation) processing of the organic film layer containing copper (Cu) generates a copper (Cu) residue after the etching, and further, a chemical solution using an organic solvent after ashing. In the treatment, it was difficult to remove the sidewall protective film generated during the etching.
JP 2003-332310 A JP-A-2-244625

  An object of the present invention is to solve the above-mentioned problems and to provide a method for forming an organic film pattern containing copper (Cu) that can obtain a good shape without remaining removal of the sidewall protective film.

In order to solve the above problems, the present invention performs etching on an organic film layer containing copper (Cu) with a plasma gas of a mixed gas of chlorine (Cl ₂ ) and oxygen (O ₂ ) through a resist mask, Then, the sidewall protective film was removed by ashing with a plasma gas of a mixed gas of methanol (CH ₃ OH), ethanol (C ₂ H ₅ OH), isopropanol (C ₃ H ₇ OH) and oxygen (O ₂ ). Thereafter, the resist mask is removed using an organic solvent (for example, toluene, xylene, acetone, or a mixed solution containing any of these or a solvent capable of removing the resist such as an amine-based resist stripping solution).

  According to the method for forming an organic film pattern containing copper (Cu) according to the present invention, the sidewall protective film is removed by performing an ashing process after etching through the resist mask, and the resist mask is formed using an organic solvent. Can be easily removed, and a favorable organic film pattern can be formed.

  In carrying out the present invention, a plasma etching processing apparatus is used as a plasma etching processing apparatus, which receives gas supply for generating plasma and generates gas plasma to etch an organic film layer formed on a substrate. As the plasma ashing processing apparatus, a plasma ashing processing apparatus for generating gas plasma upon receiving supply of plasma forming gas and ashing an organic film layer formed on the substrate was used. The plasma etching processing apparatus to which the etching method according to the present invention is applied includes a microwave plasma etching processing apparatus, an inductively coupled plasma etching processing apparatus, a helicon wave plasma etching processing apparatus, and a two-frequency excitation parallel plate type plasma etching. As a plasma ashing processing apparatus in which a processing apparatus or the like is employed and an ashing method is applied, a microwave plasma ashing processing apparatus, an inductively coupled plasma ashing processing apparatus, or the like is employed.

  An embodiment of the present invention will be described below with reference to FIGS. FIG. 2 is a conceptual diagram illustrating an outline of a configuration of a microwave plasma etching apparatus for performing an etching process in an organic film pattern forming method containing copper (Cu) by plasma etching according to the present invention. This microwave plasma etching processing apparatus includes an etching chamber 20, a microwave transmitter 21, a microwave matching unit 22, a waveguide 23, a solenoid coil 24 for generating a magnetic field, a microwave introduction window 25, And an exhaust pump 26, an exhaust pipe 27, a high-frequency power source 28, and an electrode 29. In this microwave plasma etching processing apparatus, a substrate to be processed 30 is placed on an electrode 29 and an etching gas 31 is introduced into the etching processing chamber 20.

  In this microwave plasma etching processing apparatus, an etching gas 31 is introduced into the etching processing chamber 20, and the microwave transmitted from the microwave transmitter 21 is etched from the microwave introduction window 25 through the matching unit 22 and the waveguide 23. The gas is converted into plasma by being transported to the processing chamber 20. A solenoid coil 24 for generating a magnetic field is disposed around the etching chamber 20 for high-efficiency discharge, and a high-density plasma is generated using electron cyclotron resonance by creating a magnetic field of 0.0875 Tesla. The etching chamber 20 has an electrode 29. A substrate 30 to be processed is placed on the electrode 29 and etched by gas plasma. The etching gas 31 introduced into the etching process chamber 20 is exhausted out of the etching process chamber 20 by the exhaust pump 26 and the exhaust pipe 27. A high frequency power supply 28 is connected to the electrode 29 on which the substrate to be processed 30 is installed, and a high frequency bias of 400 KHz to 13.56 MHz can be applied.

  FIG. 3 is a conceptual diagram illustrating an outline of a microwave plasma ashing apparatus for performing an ashing process in an organic film pattern forming method containing copper (Cu) by plasma etching according to the present invention. This microwave plasma ashing processing apparatus includes an ashing processing chamber 42, a microwave transmitter 21, a microwave matching unit 22, a waveguide 23, a microwave introduction window 25, an exhaust pump 26, and an exhaust pipe 27. And a sample stage 40. A substrate 30 to be processed is placed on the sample stage 40, an ashing gas 41 is introduced into the ashing chamber 42, and plasma is generated. Perform ashing.

  In this microwave plasma ashing processing apparatus, an ashing gas 41 is introduced into an ashing processing chamber 42, and the microwave transmitted from the microwave transmitter 21 is ashed from the microwave introduction window 25 through the matching unit 22 and the waveguide 23. The gas is converted into plasma by being transported to the processing chamber 42. A sample stage 40 is provided in the ashing processing chamber 42, and the substrate to be processed 30 is placed thereon and ashed by gas plasma. The ashing gas 41 introduced into the ashing processing chamber 42 is exhausted out of the ashing processing chamber by the exhaust pump 26 and the exhaust pipe 27.

  The present invention performs an etching process and an ashing process on an organic film layer containing copper (Cu) using such a microwave plasma etching apparatus and a microwave plasma ashing apparatus.

  [Reference Example 1] An etching process for an organic film pattern containing copper (Cu) in the method for forming an organic film pattern containing a metal of the present invention will be described. First, an etching process for an organic film pattern containing copper (Cu) according to the prior art will be described.

Using the microwave plasma etching apparatus of FIG. 2, as a substrate to be processed, for example, as shown in FIG. 1, a base film 2 is formed on a semiconductor substrate 1, and an organic film layer 3 containing copper (Cu) is formed. Using the resist mask 4 as a mask, the organic film layer 3 containing copper (Cu) was etched using the material to be etched. First, etching was performed with an oxygen (O ₂ ) plasma gas, which is often used for etching an organic film. The processing conditions in this processing were oxygen (O ₂ ): 100 ml / min, pressure: 0.3 Pa, microwave: 500 W, RF bias power: 50 W, processing substrate temperature: 60 ° C., etching time: end point determination. . As a result, a copper (Cu) residue was generated on the surface of the base film 2.

As a result of the etching process, in the oxygen (O ₂ ) plasma gas, the copper (Cu) contained in the organic film only becomes copper oxide (CuO) and is not etched, and a copper (Cu) residue is formed on the surface of the base film 2. I guessed that occurred. Therefore, it was considered that if a gas capable of etching copper (Cu) was used, no copper (Cu) residue was generated, and an etching gas added to oxygen (O ₂ ) was examined. As an etching gas, a fluorine-based gas, a chlorine-based gas, and a bromine-based gas were examined, but the gas added from the vapor pressure of the reaction product and the physical properties of the reaction product was chlorine (Cl ₂ ). Next, etching was performed with a plasma gas in which oxygen (O ₂ ) and chlorine (Cl ₂ ) were mixed. The processing conditions in this processing are oxygen (O ₂ ): 30 ml / min, chlorine (Cl ₂ ): 20 ml / min, pressure: 0.3 Pa, microwave: 500 W, RF bias power: 50 W, processing substrate temperature: 60 ° C. Etching time: Processing was performed by determining the end point. However, even with this treatment, a copper (Cu) residue was generated on the surface of the base film 2.

As described above, since a copper (Cu) residue is generated even in a plasma gas mixed with chlorine (Cl ₂ ) and oxygen (O ₂ ) capable of etching copper (Cu), copper contained in the organic film only by chemical reaction. (Cu) could not be etched and copper (Cu) residue was considered to be generated, and it was determined that a physical action was necessary.

  Therefore, it was considered that etching can be performed by applying a high RF bias power, attracting a large amount of ions in the plasma gas, and colliding with copper (Cu) contained in the organic film, and no copper (Cu) residue is generated. .

Example 1 Using the same microwave plasma etching apparatus and substrate to be processed as in Reference Example 1, the organic film was etched with a plasma gas in which chlorine (Cl ₂ ) and oxygen (O ₂ ) were mixed. At this time, the RF bias power supplied to the electrode 29 was 150 W.

Etching conditions are chlorine (Cl ₂ ): 40 ml / min, oxygen (O ₂ ): 10 ml / min, pressure: 0.3 Pa, microwave: 500 W, RF bias power: 150 W, processing substrate temperature: 60 ° C., etching time : Processing was determined by end point determination. As a result, no copper (Cu) residue was generated as shown in FIG.

From this result, it was confirmed that a copper (Cu) residue was not generated by applying a high RF bias power (150 W) with a plasma gas in which chlorine (Cl ₂ ) and oxygen (O ₂ ) were mixed. However, since the etching rate increases at a high RF bias power, there may be problems such as a decrease in the resist mask remaining film amount and a large amount of sidewall protective film due to reaction products adhering to a tapered shape. Also, copper (Cu) residue may be generated at low RF bias power. For this reason, the RF bias power was examined using Example 1 as a central condition.

  [Example 2] Using the same microwave plasma etching apparatus, substrate to be processed, and etching conditions as in Example 1, only RF bias power was changed to 50 W, 100 W, 120 W, 200 W, and 220 W for processing. As a result, as shown in FIG. 5, when the RF bias power was 120 W or more, the number of copper (Cu) residues generated was within the standard. In addition, when the RF bias power was 220 W, the amount of the remaining resist mask film was reduced, resulting in a tapered shape.

  As a result, when the RF bias power is 100 W, the amount of ions drawn into the plasma gas is insufficient, and the copper (Cu) contained in the organic film layer cannot sufficiently collide with the copper (Cu) residue. It is thought that. Further, when the RF bias power is 220 W, copper (Cu) is etched due to excessive ion attraction, but the resist mask is etched more than necessary, and a large amount of the side wall protective film due to the reaction product adheres. It is thought that it became a shape.

  From the above results, a vertical shape in which the number of copper (Cu) residues within the standard is the target within the RF bias power range of 120 W to 200 W was obtained.

Next, the ratio of the flow rates of chlorine (Cl ₂ ) and oxygen (O ₂ ) was examined with the RF bias power applied. If the chlorine (Cl ₂ ) flow rate is increased with the pressure and the oxygen (O ₂ ) flow rate constant, the partial pressure of oxygen (O ₂ ) decreases, the etching rate of the organic film layer decreases, the etching time increases, and the copper ( Cu) Although it is advantageous for suppressing residues, it is conceivable that problems such as a decrease in the amount of residual film of the resist mask occur when the etching time becomes long. Further, if the chlorine (Cl ₂ ) flow rate is decreased while the pressure and the oxygen (O ₂ ) flow rate are constant, the partial pressure of oxygen (O ₂ ) increases and the etching rate of the organic film layer increases. As a result, the etching time is shortened, so that the etching time of copper (Cu) contained in the organic film layer is insufficient and the flow rate of chlorine (Cl ₂ ) is small, so that it can sufficiently react with copper contained in the organic film. There is a possibility that a copper (Cu) residue is generated.

Therefore, the pressure and the oxygen (O ₂ ) flow rate are fixed with the chlorine (Cl ₂ ): 40 ml / min and oxygen (O ₂ ): 10 ml / min (the flow rate ratio of chlorine is 80%) in Example 1 as the central conditions. Only the flow rate of chlorine (Cl ₂ ) was changed, and the flow rate ratio of chlorine (Cl ₂ ) gas was examined.

[Example 3] Using the same microwave plasma etching apparatus, substrate to be processed, and etching conditions as in Example 1, only a chlorine (Cl ₂ ) flow rate of 20 ml / min (total flow rate ratio: 66%), 30 ml / Min (ratio of overall flow rate: 75%), 60 ml / min (ratio of overall flow rate: 85%), and 90 ml / min (ratio of overall flow rate: 90%). As a result, as shown in FIG. 6, when the chlorine flow rate was 30 ml / min (total flow rate ratio: 75%) or more, the number of copper (Cu) residues generated was within specifications. However, when the chlorine flow rate was 90 ml / min (ratio of the total flow rate: 90%), the residual film amount of the resist mask was reduced, resulting in a tapered shape.

As a result, when the chlorine (Cl ₂ ) flow rate is 20 ml / min (total flow rate ratio: 66%), the chlorine (Cl ₂ ) flow rate is small and the oxygen (O ₂ ) partial pressure is high. The etching time of copper (Cu) contained in the organic film is insufficient, and the chlorine (Cl ₂ ) flow rate is low and the copper (Cu) contained in the organic film cannot react sufficiently, resulting in a copper (Cu) residue. It is thought that occurred. Further, when the chlorine (Cl ₂ ) flow rate is 90 ml / min (total flow rate ratio: 90%), the chlorine (Cl ₂ ) flow rate is large and the oxygen (O ₂ ) partial pressure is low, so the etching rate of the organic film layer is slow. Although the etching time of copper (Cu) is sufficient, the remaining amount of the resist mask is reduced due to the longer etching time, and the side wall protective film due to the reaction product is attached in large quantities, so that the taper shape is considered. It is done.

From the above results, etching is performed with a gas in which chlorine (Cl ₂ ) is mixed at a ratio of 75% to 85% with respect to the entire flow rate, and oxygen (O ₂ ) at a ratio of 15% to 25% with respect to the total flow rate. As a result, a target vertical shape with the number of copper (Cu) residues within the specification was obtained.

  Next, the processing substrate temperature was examined with the RF bias power applied. When the processing substrate temperature is high, the plasma gas and copper (Cu) contained in the organic film layer easily react with each other, which is effective for suppressing copper (Cu) residue. However, it is necessary to consider the heat resistance temperature of the resist mask and the organic film layer. Generally, the heat-resistant temperature of the resist is 120 ° C to 130 ° C. Therefore, the processing substrate temperature was examined with Example 1 as a central condition.

  [Example 4] Using the same microwave plasma etching apparatus, substrate to be processed, and etching conditions as in Example 1, only the substrate temperature was processed at 20 ° C, 25 ° C, 100 ° C, and 105 ° C.

  As a result, as shown in FIG. 7, when the processing substrate temperature was 25 ° C. or higher, the number of copper (Cu) residues generated was within the standard. Further, as shown in FIG. 8, when the processing substrate temperature was 105 ° C., the resist was cured.

  From the above results, a shape was obtained in which the number of copper (Cu) residues within the standard range and the resist curing was not observed when the processing substrate temperature was in the range of 25 ° C to 100 ° C.

  Next, we decided to study ashing. In the state of only the etching process, the resist cannot be removed even if an organic solvent is used. This is thought to be because the organic solvent hardly penetrates into the sidewall protective film attached by the etching process. Accordingly, it is considered that the resist can be easily removed with an organic solvent by removing the sidewall protective film by ashing treatment or changing the properties so that it can be easily removed, and the method for forming a pattern of an organic film containing copper (Cu) according to the present invention The ashing process was examined.

[Reference Example 2] A conventional technique of ashing in a pattern forming method for an organic film containing copper (Cu) will be described below. In the examination from Reference Example 1 to Example 4, the optimum etching conditions were obtained. The processing substrate shown in FIG. 4 etched under the optimum conditions using the microwave plasma ashing processing apparatus shown in FIG. 3 is maintained in a vacuum state, while carbon tetrafluoride (CF ₄ ) and oxygen (O ₂₎ it was ashing by a plasma gas mixed with. The ashing conditions were as follows. Carbon tetrafluoride (CF ₄ ): 100 ml / min, oxygen (O ₂ ): 900 ml / min, pressure: 130 Pa, microwave: 400 mA, processing substrate temperature: 50 ° C., ashing time: 60 seconds. As a result, side etching occurred in the organic film layer by ashing.

From the result of Reference Example 2, the plasma gas mixed with carbon tetrafluoride (CF ₄ ) and oxygen (O ₂ ) of the prior art has a high ashing speed, and after removing the sidewall protective film, the organic film layer is also ashed. We thought that side etch occurred because it was closed.

[Reference Example 3] Therefore, if oxygen (O ₂ ) alone is used, the ashing rate is suppressed, and the organic film layer is not ashed. Therefore, the same microwave plasma ashing apparatus and substrate to be processed as in Reference Example 2 are used. Ashing was performed with (O ₂ ) alone plasma gas. The ashing conditions were as follows. Oxygen (O ₂ ): 900 ml / min, pressure: 130 Pa, microwave: 400 mA, processing substrate temperature: 50 ° C., ashing time: 60 seconds. As a result, side etching did not occur in the organic film layer by ashing. However, as a result of removing the resist mask with an organic solvent (a solvent containing xylene and toluene), the removal of the side wall protective film was generated.

From the result of Reference Example 3, since the sidewall protective film is not removed by ashing with oxygen (O ₂ ) alone, the sidewall protective film remains even if the resist is removed with an organic solvent (a solvent containing xylene and toluene). I thought. Therefore, in order to remove the side wall protective film, examination was made of a gas added to oxygen (O ₂ ).

The sidewall protective film deposited by the etching process was considered to be a product obtained by thermal alteration of the carbon (C) and chlorine (Cl ₂ ) polymer CxCly produced by the reaction of the resist mask and the organic film layer with the etching gas. As a result of Reference Example 2, the gas containing fluorine has an ashing speed that is too high, and as a result of investigating a gas that does not contain fluorine and halogen, attention was focused on pure water (H ₂ O) that is generally used in semiconductor manufacturing. It was considered that the sidewall protective film could be removed by the decomposition and modification of the polymer by extracting Cl with H contained in pure water (H ₂ O).

[Reference Example 4] The same microwave plasma ashing apparatus and substrate to be processed as in Reference Example 2 were ashed with a plasma gas in which oxygen (O ₂ ) and pure water (H ₂ O) were mixed. The ashing conditions were as follows. Pure water (H ₂ O): 100 ml / min, oxygen (O ₂ ): 900 ml / min, pressure: 130 Pa, microwave: 400 mA, processing substrate temperature: 50 ° C., ashing time: 60 seconds. As a result, side etching of the organic film layer occurred by ashing.

From the results of Reference Example 4, it was considered that the sidewall protective film was removed by using pure water (H ₂ O), but the organic film layer was also ashed as in Reference Example 2 and side etching occurred. It was. Therefore, in order to suppress ashing of the organic film layer, it was considered effective to add a gas that generates a depositing CH component, and a gas containing CH and H, which does not contain fluorine and halogen, was examined. Since the depotability is expected to increase when there are many CH components, methanol (CH ₃ OH), ethanol (C ₂ H ₅ OH), isopropanol, which contain moderate CH and are generally used for semiconductor production Attention was paid to (C ₃ H ₇ OH).

[Example 5] The same microwave plasma ashing processing apparatus and substrate to be processed as in Reference Example 2 were ashed with a plasma gas in which methanol (CH ₃ OH) and oxygen (O ₂ ) were mixed. The ashing conditions were as follows. Methanol (CH ₃ OH): 100 ml / min, oxygen (O ₂ ): 900 ml / min, pressure: 130 Pa, microwave: 400 mA, processing substrate temperature: 50 ° C., ashing time: 60 seconds. As a result, no side etching occurs in the organic film layer by ashing, and then the sidewall protective film 5 and the photoresist layer 4 are removed as shown in FIG. 9 when treated with an organic solvent (a solvent containing xylene and toluene). These removal residues did not occur.

From the results of Example 5, by using a plasma gas in which methanol (CH ₃ OH) and oxygen (O ₂ ) are mixed, side etching is not generated in the organic film layer, and an organic solvent (a solvent containing xylene and toluene) is used. ), It was confirmed that the resist mask could be removed. As the gas added to oxygen (O ₂ ), ethanol (C ₂ H ₅ OH) having the same degree of CH other than methanol (CH ₃ OH) and isopropanol (C ₃ H ₇ OH) can obtain the same effect. .

However, if the ratio of the total flow rate of plasma (methanol (CH ₃ OH)) is large, the amount of CH is too much and the deposition property becomes strong and the side wall protective film cannot be removed, and the ratio of the total flow rate of methanol (CH ₃ OH) If the amount is small, the deposition property becomes weak and side etching may occur in the organic film layer. Therefore, methanol (CH ₃ OH) of Example 5: 100 ml / min (ratio of the total flow rate: 10%) and pressure were fixed, and only the oxygen (O ₂ ) flow rate was changed, and methanol (CH ₃ OH) and oxygen ( The examination of the O ₂ ) flow rate ratio was carried out.

[Example 6] Using the same apparatus, substrate, and processing conditions as in Example 5, only the oxygen (O ₂ ) flow rate was 250 ml / min (ratio of total methanol flow rate: 28%), 300 ml / min (methanol) The total flow rate was 25%), 600 ml / min (ratio of the total flow rate of methanol: 14%), and 1100 ml / min (ratio of the total flow rate of methanol: 8%). Side etch occurred in the organic film layer at 1100 ml / min after ashing (ratio of the total flow rate of methanol: 8%). The resist mask was removed with an organic solvent (a solvent containing xylene and toluene) from a sample in which side etching did not occur in the organic film layer.

As a result, as shown in FIG. 10, when the flow rate of oxygen (O ₂ ) is 250 ml / min (ratio of the total flow rate of methanol: 28%), residual removal of the side wall protective film occurs, and as shown in FIG. ₂ ) Side etch occurred in the organic film layer at a flow rate of 1100 ml / min (ratio of the total flow rate of methanol: 8%).

This is considered that when the ratio of methanol (CH ₃ OH) in the entire ashing gas flow rate exceeds 25%, CH increases, the deposition property becomes strong, and the sidewall protective film cannot be removed. If the proportion of the total flow rate of methanol (CH ₃ OH) is less than 10%, the deposition property is weak, and it is considered that side etching has occurred in the organic film layer.

From the above results, ashing is performed with a gas in which methanol (CH ₃ OH) is mixed at a ratio of 10% to 25% with respect to the entire flow rate, and oxygen (O ₂ ) at a ratio of 75% to 90% with respect to the total flow rate. As a result, a shape in which no side etching occurred in the organic film layer and there was no remaining removal of the sidewall protective film was obtained.

  Next, the processing substrate temperature in the ashing processing was examined. If the processing substrate temperature is high, the ashing speed is high, but the resist mask is cured at a high temperature, and the sidewall protective film is similarly cured. Once cured, the sidewall protective film cannot be removed by ashing. In addition, if the processing substrate temperature is low, the ashing speed becomes slow, so that the side wall protective film may not be removed.

  [Example 7] Using the same microwave plasma ashing processing apparatus, substrate to be processed and processing conditions as in Example 5, processing was performed only at the processing substrate temperature at 20 ° C, 25 ° C, 100 ° C, 105 ° C, and then the organic solvent. The resist mask was removed with (a solvent containing xylene and toluene). As a result, as shown in FIG. 12, when the substrate temperature to be processed is 20 ° C. and 105 ° C., residual removal of the sidewall protective film occurs, and when the substrate temperature to be processed is 105 ° C., the resist is cured. It was.

  From the above results, a shape was obtained in which the organic substrate layer had no side etch, no side wall protective film was removed, and no resist was cured when the processing substrate temperature was in the range of 25 ° C. to 100 ° C.

  Next, the processing time in the ashing process was examined. If the ashing time is short, the sidewall protective film cannot be removed, and if it is long, side etching may occur in the organic film layer.

  [Example 8] Using the same microwave plasma ashing processing apparatus, substrate to be processed and processing conditions as in Example 5, the processing time was 30 seconds, 40 seconds, 80 seconds and 90 seconds. In 90 seconds after ashing, side etching occurred in the organic film layer. The resist mask was removed with an organic solvent (a solvent containing xylene and toluene) from a sample in which side etching did not occur in the organic film layer.

  As a result, if the processing time is 40 seconds or longer as shown in FIG. 14, no removal of the sidewall protective film remains, and if it is longer than 80 seconds as shown in FIG. 15, side etching occurs.

  As a result, it is considered that the sidewall protective film could not be removed in 30 seconds, the sidewall protective film was removed in 90 seconds, and the organic film layer was ashed.

  From the above results, a good shape was obtained in which the side wall protective film was not removed when the treatment time ranged from 40 seconds to 80 seconds.

  According to the present embodiment, through the above-described steps, it becomes possible to perform predetermined patterning by etching an organic film containing copper (Cu) without copper (Cu) residue, and ashing the sidewall protective film Then, by making the organic solvent easily infiltrated into the resist and removing the resist mask with the organic solvent, a predetermined organic film pattern can be formed and fine processing can be realized. .

After etching of a mixed gas of chlorine (Cl ₂ ) and oxygen (O ₂ ), one of methanol (CH ₃ OH), ethanol (C ₂ H ₅ OH), isopanol (C ₃ H ₇ OH) and oxygen (O ₂ ) Ashing treatment is performed with a mixed gas of Thereafter, the remaining resist mask layer is removed using an organic solvent, so that the resist layer can be completely removed and the organic film can be patterned with high accuracy without adversely affecting the organic film pattern.

Sectional drawing which illustrates notionally the structure of the to-be-processed substrate which carried out the etching process. Sectional drawing explaining the outline | summary of a structure of the microwave plasma etching processing apparatus to which the etching process of the organic film pattern formation method which concerns on this invention is applied. Sectional drawing explaining the outline | summary of a structure of the microwave plasma ashing processing apparatus to which the ashing process of the organic film pattern formation method which concerns on this invention is applied. Sectional drawing which shows notionally the structure of the to-be-processed substrate after the etching process of this invention. The figure explaining the relationship between RF bias power and metal residue in this invention. The figure explaining the relationship between the ratio of the chlorine in the whole flow volume of the etching gas in this invention, and a metal residue. The figure explaining the relationship between the process substrate temperature and metal residue in this invention. The figure explaining the relationship between the process substrate temperature and resist hardness in this invention. Sectional drawing which shows notionally the structure of the to-be-processed substrate after the ashing process of this invention. The figure explaining the ratio of the methanol in the whole flow rate of the ashing gas in this invention, and the relationship of removal remainder. The figure explaining the relationship between the ratio of the methanol in the whole flow rate of the ashing gas in this invention, and organic film side etching. The figure explaining the process substrate temperature in this invention, and the relationship of the removal remainder. The figure explaining the process substrate temperature in this invention, and the relationship of the removal remainder. The figure explaining the processing time in this invention, and the relationship of the removal remainder. The figure explaining the relationship between the processing time in this invention, and organic film side etching.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Base film, 3 ... Organic film containing copper (Cu), 4 ... Photoresist layer, 5 ... Side wall protective film, 12 ... Organic film pattern containing copper (Cu), 20 ... Etching process chamber , 21 ... Microwave transmitter, 22 ... Microwave matching unit, 23 ... Waveguide, 24 ... Solenoid coil, 25 ... Microwave introduction window, 26 ... Exhaust pump, 27 ... Exhaust piping, 28 ... High frequency power supply, 29 ... Electrode, 30 ... sample, 31 ... etching gas, 40 ... sample stage, 41 ... ashing gas, 42 ... ashing treatment chamber

Claims (5)

Etching process of patterning a polyimide or acrylic organic film containing copper (Cu) by dry etching with plasma gas mixed with chlorine (Cl ₂ ) and oxygen (O ₂ ) through a resist mask on a processing substrate When,
The sidewall protective film attached in the etching process is a plasma gas obtained by mixing one of methanol (CH ₃ OH), ethanol (C ₂ H ₅ OH), isopropanol (C ₃ H ₇ OH) and oxygen (O ₂ ). An organic film pattern forming method comprising: an ashing process step of ashing. In the formation method of the organic film pattern of Claim 1,
In the dry etching process, chlorine (Cl ₂ ) is mixed at a ratio of 75% to 85% with respect to the total flow rate, and oxygen (O ₂ ) is mixed at a ratio of 15% to 25% with respect to the total flow rate.
In the ashing treatment step, one of methanol (CH ₃ OH), ethanol (C ₂ H ₅ OH), and isopropanol (C ₃ H ₇ OH) is 10% to 25% with respect to the total flow rate, oxygen (O ₂ ). Is formed at a ratio of 75% to 90% with respect to the total flow rate. In the formation method of the organic film pattern of Claim 1,
A method of forming an organic film pattern, characterized in that a processing substrate temperature is set to 25 ° C. to 100 ° C. in the dry etching processing step, and a processing substrate temperature is set to 25 ° C. to 100 ° C. in the ashing processing step. In the formation method of the organic film pattern of Claim 1,
An organic film pattern forming method comprising performing an etching process by applying an RF bias power of 120 W to 200 W in the dry etching process. In the formation method of the organic film pattern of Claim 1,
In the ashing treatment step, an ashing treatment is performed at a treatment time of 40 seconds to 80 seconds.

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