JP2009164151A - Method of forming resist pattern, system for removal processing of remaining film, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a resist pattern without a remaining film and easily re-form a resist pattern by less processes when processing of forming a resist pattern by double patterning. <P>SOLUTION: A method is used to form a specified resist pattern on a base film B on the surface of a substrate W. The substrate W is subject to a first patterning process wherein a first resist pattern P1 is formed beforehand on the base film B and a second patterning process wherein a second resist pattern P2 is formed on the base film B. Then the substrate W is subject to a remaining film removal process, wherein a remaining film D' is removed from the first resist pattern P1. Since the remaining film removal process is conducted to remove the remaining film D' from the first resist pattern P1, a resist pattern without the remaining film D' can be formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resist pattern forming method and a residual film removal processing system, and further relates to a recording medium on which a program is recorded.

  For example, in a photolithography process in a semiconductor device manufacturing process, a resist coating process is performed by applying a resist solution on a film to be etched, which is a base film on the wafer surface, and a predetermined pattern of light is applied to the resist film on the wafer. Then, an exposure process for exposing the resist film, a development process for developing the exposed resist film, and the like are sequentially performed to form a predetermined resist pattern on the wafer. Thereafter, for example, the etching target film is etched using the resist pattern as an etching mask, and a predetermined pattern is formed on the etching target film.

  Conventionally, in order to make the pattern finer, it has been promoted to shorten the wavelength of the light for the exposure process. However, it is technically difficult to form a fine pattern of 32 nm or 45 nm level, for example, by this method of shortening the wavelength of exposure. Therefore, the first patterning process for forming the first resist pattern on the etching target film, which is the base film, and the second patterning process for forming the second resist pattern are sequentially performed to form a fine pattern. A method of forming an etching mask (hereinafter referred to as “double patterning”) has been considered (see, for example, Patent Document 1).

JP 2006-303504 A

  By the way, in the double patterning, there is a case where a remaining film such as a silicon oxide film remains on the first resist pattern when the second patterning process is performed. In such a case, if the remaining resist film is present on the first resist pattern and the remaining resist film is not present on the second resist pattern, the first resist pattern and the second resist pattern can be obtained by performing the etching process as it is. If the resist pattern conditions are different, the pattern shape formed on the etched film may be disturbed.

  The present invention has been made in view of this point, and an object of the present invention is to form a resist pattern having no remaining film in the resist pattern forming process by the double patterning described above.

  In order to achieve the above object, according to the present invention, there is provided a method for forming a predetermined resist pattern on a base film on a substrate surface, wherein the first hard mask and the second hard mask are formed on the base film on the substrate surface. A first patterning process for transferring the first resist pattern to the second hard mask, and a second patterning for transferring the first resist pattern and the second resist pattern to the first hard mask. There is provided a method for forming a resist pattern, which includes a processing step and a step of removing a remaining film of the second hard mask from the first hard mask.

  The second hard mask is, for example, a silicon oxide film. In this case, the silicon oxide film contains, for example, at least one of boron and phosphorus. Examples of the silicon oxide film include a BPSG film, a BSG film, and a PSG film.

The step of removing the remaining film of the second hard mask from the first hard mask is as follows:
The step of bringing the substrate to a first processing temperature, supplying a gas containing a halogen element, chemically reacting the silicon oxide film and the gas containing the halogen element, and transforming the silicon oxide film into a reaction product. And removing the silicon oxide film transformed into the reaction product by setting the substrate to a second processing temperature higher than the first processing temperature.

  Further, according to the present invention, there is provided a method for forming a predetermined resist pattern on a base film on a substrate surface, and a first patterning process step for forming a first resist pattern on the base film in advance, Performing a residual film removing process for removing the residual film from the first resist pattern on the substrate on which the second patterning process for forming the second resist pattern on the base film has been performed. A method for forming a resist pattern is provided.

  The remaining film is, for example, a silicon oxide film. In this case, the silicon oxide film contains, for example, at least one of boron and phosphorus. Examples of the silicon oxide film include a BPSG film, a BSG film, and a PSG film.

  In the remaining film removal treatment step, the substrate is brought to a first treatment temperature, a gas containing a halogen element is supplied, and the silicon oxide film and the gas containing the halogen element are caused to chemically react with each other. And a step of removing the silicon oxide film transformed into the reaction product by setting the substrate to a second treatment temperature higher than the first treatment temperature. You may do it.

  Note that the gas containing a halogen element is, for example, a gas containing hydrogen fluoride. The step of transforming the silicon oxide film into a reaction product may be performed under a predetermined reduced pressure. Further, the step of removing the reaction product by heating may be performed under a predetermined reduced pressure. In the step of removing the reaction product by heating, a basic gas may be supplied. In this case, the basic gas is, for example, ammonia gas.

  Further, the base film is, for example, a film to be etched. In this case, the etching target film is made of, for example, polysilicon or a silicon oxide film.

  Further, according to the present invention, there is a residual film removal processing system for removing a residual film from a resist pattern formed on a base film on a substrate surface, the reaction processing apparatus for transforming the residual film into a reaction product, A heat treatment device that heat-treats the remaining film transformed into the reaction product, the reaction treatment device placing a substrate in the reaction treatment chamber, a reaction treatment chamber that houses the substrate, and the reaction treatment chamber. And a gas supply source for supplying a gas containing a halogen element into the reaction processing chamber, and the heat treatment apparatus includes: a heat treatment chamber for housing the substrate; and the heat treatment chamber. And a mounting table for placing the substrate on the substrate and bringing the substrate to a desired temperature.

  In this residual film removal processing system, the gas containing the halogen element is, for example, a gas containing hydrogen fluoride.

  Moreover, you may provide the inert gas supply source which supplies an inert gas in the said reaction processing chamber. Moreover, you may have the pressure-reduction mechanism which depressurizes the said reaction processing chamber to a desired pressure.

  The heat treatment apparatus may include a gas supply source for supplying a basic gas into the heat treatment chamber. In this case, the basic gas is, for example, ammonia gas.

  Moreover, you may provide the inert gas supply source which supplies an inert gas in the said heat processing chamber. Moreover, you may have the pressure reduction mechanism which pressure-reduces the said heat processing chamber to a desired pressure.

  Furthermore, according to the present invention, there is provided a recording medium on which a program that can be executed by a control computer of a processing system is recorded, and the program is executed by the control computer, whereby the processing system There is provided a recording medium characterized by performing the resist pattern forming method.

  According to the present invention, in the process of forming a resist pattern by double patterning, there is no residual film on the first resist pattern by performing the step of removing the residual film of the second hard mask from the first resist pattern. A resist pattern can be formed. For this reason, the conditions of the first resist pattern and the second resist pattern are the same, and, for example, when the etching process is performed thereafter, the pattern shape formed on the film to be etched is not disturbed, and the etching processing accuracy is improved. To do.

  Hereinafter, preferred embodiments of the present invention will be described. In the following embodiments, the remaining film D of the second hard mask D is formed on the first resist pattern P1 formed on the etching target film B as a base film exposed on the surface of the wafer W which is a semiconductor substrate. The residual film removal processing system 1 for removing 'will be specifically described. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  A residual film removal processing system 1 shown in FIG. 1 includes a loading / unloading unit 2 for loading / unloading a wafer W into / from the residual film removal processing system 1, a load lock chamber 3 that can be evacuated, and a halogen element for the wafer W. A reaction processing apparatus 4 that performs a reaction process for supplying a gas to transform the remaining film D ′ of the second hard mask D into a reaction product, and a heat treatment after the reaction process (PHT (Post Heat Treatment)) on the wafer W And a control computer 6 for giving a control command to each part of the residual film removal processing system 1. In this residual film removal processing system 1, two reaction processing apparatuses 4 and two heat treatment apparatuses 5 are provided, and the wafers W loaded from the loading / unloading unit 2 are subjected to reaction processing via the load lock chamber 3 in parallel. The wafer 4 is transferred to the loading / unloading unit 2 again through the load lock chamber 3 by being transferred in the order of the apparatus 4 and the heat treatment apparatus 5 and processed.

  The carry-in / out unit 2 includes a transfer mechanism 10 capable of transferring the wafer W, and a carrier mounting table 11 on which a carrier C capable of accommodating a plurality of wafers W arranged side by side is placed on the side of the transfer mechanism 10. For example, three are provided. Further, for example, an orienter 12 that performs alignment by rotating a wafer W having a substantially disk shape is provided. The transfer mechanism 10 can arbitrarily transfer the wafers W one by one between the three carriers C, the orienter 12 and the two load lock chambers 3.

  The load lock chamber 3 includes a gate valve that can be opened and closed between the loading / unloading unit 2 and the heat treatment apparatus 5. Therefore, the wafer W is loaded from the loading / unloading unit 2 to the reaction processing apparatus 4 and the heat treatment apparatus 5 while being kept at a predetermined pressure in the reaction processing apparatus 4 and the heat treatment apparatus 5 and loaded from the reaction processing apparatus 4 and the heat treatment apparatus 5. The wafer W can be carried out to the exit part 2.

  As shown in FIG. 2, the reaction processing apparatus 4 includes a sealed reaction processing chamber 20 that houses a wafer W, and a mounting table 21 that holds the wafer W substantially horizontally in the reaction processing chamber 20. Is provided. The mounting table 21 is provided with temperature adjusting means 22 for bringing the wafer W to a desired temperature. Although not shown, a loading / unloading port for loading / unloading the wafer W to / from the PHT processing apparatus 5 is provided on the side of the reaction processing chamber 20.

Further, the reaction processing apparatus 4 includes a supply path 25 for supplying hydrogen fluoride gas (hydrogen fluoride) as a processing gas containing a halogen element into the reaction processing chamber 20, and nitrogen gas as a dilution gas in the reaction processing chamber 20. A supply path 26 for supplying an inert gas such as (N ₂ ) and an exhaust path 27 for exhausting the reaction processing chamber 20 are connected. The supply path 25 is connected to a supply source 30 of hydrogen fluoride gas, and the supply path 25 is provided with a flow rate adjusting valve 31 that can be opened and closed and the supply flow rate of hydrogen fluoride gas can be adjusted. The supply path 26 is connected to a nitrogen gas supply source 35, and the supply path 26 is provided with a flow rate adjustment valve 36 that can be opened and closed and the supply flow rate of the nitrogen gas can be adjusted.

  In the ceiling of the reaction processing chamber 20, the hydrogen fluoride gas and the nitrogen gas supplied through the supply path 25 and the supply path 26 are uniformly supplied to the entire upper surface of the wafer W placed on the mounting table 21. A shower head 37 is provided.

  The exhaust passage 27 is provided with a pressure controller 40 and an exhaust pump 41 for performing forced exhaust. By operating the exhaust pump 41 and adjusting the pressure controller 40, the inside of the reaction processing chamber 20 is depressurized to a predetermined pressure.

  As shown in FIG. 3, the heat treatment apparatus 5 includes a sealed heat treatment chamber 50 that accommodates the wafer W, and a mounting table 51 that holds the wafer W substantially horizontally is provided in the heat treatment chamber 50. ing. The mounting table 51 is provided with temperature adjusting means 52 for bringing the wafer W to a desired temperature. Although not shown, on the side of the heat treatment chamber 50, there is a wafer between the load lock chamber 3 and a loading / unloading port for loading / unloading the wafer W to / from the reaction processing chamber 20 of the reaction processing apparatus 4. A loading / unloading port for loading and unloading W is provided.

Further, the heat treatment apparatus 5 is connected to a supply passage 55 for supplying an inert gas such as nitrogen gas (N ₂ ) as a dilution gas into the heat treatment chamber 50 and an exhaust passage 56 for exhausting the heat treatment chamber 50. . The supply path 55 is connected to a nitrogen gas supply source 60. The supply path 55 is provided with a flow rate adjustment valve 61 that can be opened and closed and the supply flow rate of the nitrogen gas can be adjusted.

  A shower head 62 for uniformly supplying the nitrogen gas supplied through the supply path 55 to the entire upper surface of the wafer W placed on the mounting table 51 is provided at the ceiling of the heat treatment chamber 50.

  The exhaust path 56 is provided with a pressure controller 65 and an exhaust pump 66 for performing forced exhaust. By operating the exhaust pump 66 and adjusting the pressure controller 65, the inside of the heat treatment chamber 50 is depressurized to a predetermined pressure.

  Each functional element of the residual film removal processing system 1 is connected via a signal line to a control computer 6 that automatically controls the operation of the entire residual film removal processing system 1. Here, the functional elements include, for example, the above-described temperature adjusting means 22 of the reaction processing apparatus 4, flow rate adjusting valves 31, 36, pressure controller 65, exhaust pump 66, temperature adjusting means 52 of the heat treatment apparatus 5, flow rate adjusting valve 61, It means all elements that operate to achieve a predetermined process condition, such as the pressure controller 65 and the exhaust pump 66. The control computer 6 is typically a general-purpose computer that can realize any function depending on the software to be executed.

  As shown in FIG. 1, the control computer 6 includes a calculation unit 6a having a CPU (central processing unit), an input / output unit 6b connected to the calculation unit 6a, and control software inserted into the input / output unit 6b. And a stored recording medium 6c. The recording medium 6c stores control software (program) that is executed by the control computer 6 to cause the residual film removal processing system 1 to perform a predetermined substrate processing method to be described later. The control computer 6 executes the control software, thereby causing each functional element of the residual film removal processing system 1 to have various process conditions defined by a predetermined process recipe (for example, pressure in the processing chambers 20 and 50, etc.). ) Is realized.

  The recording medium 6c may be fixedly provided in the control computer 6, or may be detachably attached to a reading device (not shown) provided in the control computer 6 and readable by the reading device. In the most typical embodiment, the recording medium 6 c is a hard disk drive in which control software is installed by a serviceman of the manufacturer of the residual film removal processing system 1. In another embodiment, the recording medium 6c is a removable disk such as a CD-ROM or DVD-ROM in which control software is written. Such a removable disk is read by an optical reading device (not shown) provided in the control computer 6. Further, the recording medium 6c may be in any format of RAM (random access memory) or ROM (read only memory). Further, the recording medium 6c may be a cassette type ROM. In short, any medium known in the technical field of computers can be used as the recording medium 6c. In a factory where a plurality of remaining film removal processing systems 1 are arranged, control software may be stored in a management computer that comprehensively controls the control computer 6 of each remaining film removal processing system 1. In this case, each residual film removal processing system 1 is operated by a management computer via a communication line and executes a predetermined process.

  Next, double patterning using the remaining film removal processing system 1 according to the embodiment of the present invention configured as described above will be described.

  FIG. 4 is a flowchart of an etching process using double patterning. 5-10 is explanatory drawing which shows the change of the film | membrane structure of the wafer W in double patterning.

First, for example, as shown in FIG. 5A, a target etching target film B such as organic polysilicon is formed on a gate oxide film A such as SiO on the wafer W, and SiN or the like is formed thereon. A first hard mask C and a second hard mask D such as SiO ₂ are formed, and an organic film E1 and an SOG film F1 which is an inorganic coating film are formed thereon. The etched film B may be a silicon oxide film that does not contain boron and phosphorus. The second hard mask D contains at least one of boron and phosphorus. For example, a BPSG (Boro-Phospho Silicated Glass) film, BSG (Boro (Boro))
Silicated Glass) film and PSG (Phospho Silicated Glass) film.

  Then, the photolithography process of the first patterning process (step S1 in FIG. 4) is started. As shown in FIG. 5B, the antireflection film G1 and the resist film H1 are formed on the surface of the SOG film F1 on the wafer W. It is formed. The formation of the antireflection film G1 and the resist film H1 is performed by, for example, a coating method in which a coating liquid is supplied and coated on the rotated wafer W.

  Subsequently, the resist film H1 is exposed to a predetermined pattern and developed to form a first resist pattern P1 as shown in FIG.

  Next, as shown in FIG. 6A, the lower antireflection film G1 and SOG film F1 are etched using the first resist pattern P1 as a mask, and then the SOG film F1 is etched as shown in FIG. 6B. Using this pattern as a mask, the organic film E1 is etched. For example, at this time, the first resist pattern P1 and the antireflection film G1 are also removed.

  Subsequently, as shown in FIG. 6C, the second hard mask D is etched using the pattern of the organic film E1 as a mask. For example, at this time, the SOG film F1 is removed. Thus, the first resist pattern P1 is transferred to the second hard mask D.

  Next, the photolithography process of the second patterning process (step S2 in FIG. 4) is started, and the same kind of organic film E2 and SOG film are again formed on the second hard mask D as shown in FIG. 7A. F2 is formed. Thereafter, as shown in FIG. 7B, an antireflection film G2 and a resist film H2 are formed on the SOG film F2.

  Subsequently, the resist film H2 is exposed to a predetermined pattern and developed to form a second resist pattern P2 as shown in FIG. 7C.

  Next, as shown in FIG. 8A, the lower anti-reflection film G2 and SOG film F2 are etched using the second resist pattern P2 as a mask, and then the SOG film F2 is etched as shown in FIG. 8B. The organic film E2 is etched using this pattern as a mask. For example, at this time, the second resist pattern P2 and the antireflection film G2 are removed.

  Thereafter, as shown in FIG. 8C, the first hard mask C is etched using the pattern of the organic film E2 and the second hard mask D as a mask. Thereafter, as shown in FIG. 8D, the SOG film F2 and the organic film E2 are removed. In this way, an etching mask having a fine dimension in which the first resist pattern P1 and the second resist pattern P2 are transferred to the first hard mask C is formed.

  Here, in the double patterning as described above, when the second patterning process is performed, a remaining film of the second hard mask D (for example, a BPSG film, a BSG film, or a PSG film) is formed on the first resist pattern P1. D 'may remain. In such a case, there is a residual film D ′ on the first resist pattern P1, while there is no such residual film on the second resist pattern P2. When the etching pattern for the etching target film B is next performed using the resist pattern P2 as an etching mask as it is, the first resist pattern P1 and the second resist pattern P2 are formed on the etching target film B due to different conditions. The pattern shape may be disturbed. That is, for example, when the remaining film D ′ is present on the first resist pattern P1, the height of the first resist pattern P1 becomes higher than that of the second resist pattern P2, and the etching film B is etched. It is feared that the conditions for entering the etchant are not equal to each other, and the pattern shape formed in the film to be etched B is deteriorated.

  Therefore, in the residual film removal processing system 1 according to the embodiment of the present invention, the substrate in which the first resist pattern P1 and the second resist pattern P2 are previously transferred to the first hard mask C by the double patterning as described above. For W, a step of removing the remaining film D ′ of the second hard mask D from the first resist pattern P1 is performed (step S3 in FIG. 4). That is, first, as shown in FIG. 8D, the first resist pattern P1 and the second resist pattern P2 are transferred to the first hard mask C on the surface of the wafer W, and the first resist pattern P1 is formed on the first resist pattern P1. The wafer W with the remaining film D ′ remaining is stored in the carrier C and carried into the remaining film removal processing system 1.

  In the remaining film removal processing system 1, as shown in FIG. 1, the carrier C in which a plurality of wafers W are stored is placed on the carrier mounting table 11. Then, one wafer W is taken out from the carrier C by the wafer transfer mechanism 10 and is carried into the load lock chamber 3. When the wafer W is loaded into the load lock chamber 3, the load lock chamber 3 is sealed and decompressed. Thereafter, the load lock chamber 3 is connected to the reaction processing chamber 20 of the reaction processing apparatus 4 and the heat treatment chamber 50 of the heat treatment apparatus 5 that have been decompressed in advance.

  The wafer W is first carried into the reaction processing chamber 20 of the reaction processing apparatus 4. The wafer W is mounted on the mounting table 21 in the reaction processing chamber 20 with the surface (device forming surface) as the upper surface. As a result, as shown in FIG. 8D, the first hard mask C formed on the surface of the wafer W is directed upward in the reaction processing chamber 20, and the first resist pattern P1 and the second resist The pattern P2 and the remaining film D ′ remaining on the first resist pattern P1 are set to face upward in the reaction processing chamber 20.

  When the wafer W is loaded into the reaction processing apparatus 4 in this way, the reaction processing chamber 20 is sealed, and the reaction processing step is started. That is, the wafer W is set to the first processing temperature by the temperature adjusting means 22. In this case, the first processing temperature is, for example, 40 ° C. or lower.

  Further, the inside of the reaction processing chamber 20 is forcibly evacuated through the exhaust passage 27, and the inside of the reaction processing chamber 20 is brought into a predetermined reduced pressure state. In this case, the pressure in the reaction processing chamber 20 is set to, for example, 400 to 4000 Pa (3 to 30 Torr) by operating the exhaust pump 41 and adjusting the pressure controller 40.

  Then, hydrogen fluoride gas and nitrogen gas are respectively supplied into the reaction processing chamber 20 through the supply paths 25 and 26 at predetermined flow rates. In this case, the supply amount of the hydrogen fluoride gas is adjusted to, for example, 1000 to 3000 sccm by adjusting the flow rate adjustment valve 31. Further, the supply amount of nitrogen gas is adjusted to, for example, 500 to 3000 sccm by adjusting the flow rate adjusting valve 36. In addition, by supplying nitrogen gas into the reaction processing chamber 20 in addition to the hydrogen fluoride gas which is a reaction gas, the heat of the temperature control means 22 incorporated in the mounting table 21 is efficiently conducted to the wafer W, and the wafer The temperature of W is accurately controlled.

By supplying the hydrogen fluoride gas under reduced pressure in this way, the remaining film D ′ remaining on the first resist pattern P1 on the surface of the wafer W chemically reacts with the hydrogen fluoride gas. As a result, the remaining film D ′ made of, for example, a BPSG film, a BSG film, or a PSG film is transformed into a reaction product D ″ mainly made of fluorosilicic acid (H ₂ SiF ₆ ) (FIG. 9A). In this case, since the film to be etched B is, for example, an organic polysilicon film or a silicon oxide film that does not contain boron and phosphorus, it is avoided that the film is etched into a reaction product.

  Thus, when the reaction process for transforming the remaining film D ′ remaining on the first resist pattern P1 into the reaction product D ″ is completed, the flow control valve 31 is closed and the supply of hydrogen fluoride gas is stopped. The supply of nitrogen gas through the supply path 26 is further continued, and the inside of the reaction processing chamber 20 is purged with nitrogen gas, and then the carry-in / out port of the reaction processing apparatus 4 is opened to open the reaction processing apparatus. 4 and the heat treatment chamber 50 of the heat treatment apparatus 5 are communicated with each other, and the wafer W is transferred from the treatment chamber 20 of the reaction treatment apparatus 4 to the heat treatment chamber 50 of the heat treatment apparatus 5.

  Next, in the heat treatment apparatus 5, the wafer W is placed on the placement table 51 in the heat treatment chamber 50 with the surface on which the first hard mask C is formed as the upper surface. As a result, the reaction product D ″ remaining on the first resist pattern P1 is also directed upward in the heat treatment chamber 50.

  When the wafer W is thus carried into the heat treatment apparatus 5, the heat treatment chamber 50 is sealed, and the heat treatment process is started. That is, the temperature adjustment means 52 sets the wafer W to a second processing temperature higher than the first processing temperature. In this case, the second processing temperature is, for example, 100 to 400 ° C.

  Further, the inside of the heat treatment chamber 50 is forcibly exhausted through the exhaust passage 56, and the inside of the heat treatment chamber 50 is brought into a predetermined reduced pressure state. In this case, the pressure in the heat treatment chamber 50 is set to 133 to 400 Pa (1 to 3 Torr), for example, by operating the exhaust pump 66 and adjusting the pressure controller 65.

  Then, nitrogen gas is supplied into the heat treatment chamber 50 through the supply path 55 at a predetermined flow rate. In this case, the supply amount of the nitrogen gas is adjusted to, for example, 500 to 3000 sccm by adjusting the flow rate adjusting valve 61. Thereby, the heat of the temperature adjusting means 52 built in the mounting table 51 is efficiently conducted to the wafer W, and the temperature of the wafer W is accurately controlled.

In this way, the reaction product D ″ generated by the reaction process is heated and vaporized as SiF ₄ gas and hydrogen fluoride gas, and is removed from the first resist pattern P1. ), The reaction product D ″ is removed from the first resist pattern P1, and only the first resist pattern P1 and the second resist pattern P2 remain on the first hard mask C. Become. In this case, since the film to be etched B is not transformed into a reaction product as described above, it is not removed even if heated.

  When the heat treatment is completed, the flow rate adjustment valve 61 is closed and the supply of nitrogen gas is stopped. And the entrance / exit of the heat processing apparatus 5 is opened. Thereafter, the wafer W is unloaded from the heat treatment chamber 50 and loaded into the load lock chamber 3. When the wafer W is loaded into the load lock chamber 3, the load lock chamber 3 is sealed and set to atmospheric pressure, and then the load lock chamber 3 and the loading / unloading unit 2 are communicated with each other. Then, the wafer W is unloaded from the load lock chamber 3 by the transfer mechanism 10 and returned to the carrier C on the carrier mounting table 11. As described above, a series of steps in the residual film removal processing system 1 is completed.

  Next, as shown in FIG. 10, the to-be-etched film B is etched using the first resist pattern P1 and the second resist pattern P2 (first hard mask C) as a mask (step S4 in FIG. 4). Thus, a desired fine pattern is formed on the target film B to be etched.

  According to such a processing method, in the resist pattern forming process by double patterning, the remaining film removal process step of removing the remaining film D ′ from the first resist pattern P1 is performed, whereby the resist pattern without the remaining film D ′ is obtained. Can be formed. For this reason, when an etching process etc. are performed after that, the pattern shape formed in the to-be-etched film B is not disturbed, and an etching processing precision improves.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  For example, the heat treatment apparatus 5 shown in FIG. 3 is configured to supply only the inert gas into the heat treatment chamber 50. However, as in the heat treatment apparatus 5 ′ shown in FIG. In addition, a supply path 70 for supplying ammonia gas as a basic gas may be connected. The supply path 70 is connected to an ammonia gas supply source 71, and the supply path 70 is provided with a flow rate adjusting valve 72 capable of opening and closing and adjusting the supply flow rate of the ammonia gas. The heat treatment apparatus 5 ′ shown in FIG. 11 has the same configuration as the heat treatment apparatus 5 described above with reference to FIG. 3 except that a supply path 70 for supplying ammonia gas is connected to the heat treatment chamber 50. is doing.

When the residual film D ′ is removed from the first resist pattern P1 by the residual film removal processing system 1 provided with the heat treatment apparatus 5 ′, the first resist pattern P1 is used in the reaction processing apparatus 4 as described above. The remaining film D ′ remaining thereon is chemically reacted with hydrogen fluoride gas to be transformed into a reaction product D ″ mainly composed of fluorosilicic acid (H ₂ SiF ₆ ). Thereafter, the wafer W is reacted. It is moved from the processing chamber 20 of the processing apparatus 4 to the thermal processing chamber 50 of the thermal processing apparatus 5 ′, and the reaction product D ″ on the first resist pattern P1 is in an upward orientation in the thermal processing chamber 50. .

  When the wafer W is thus carried into the heat treatment apparatus 5 ′, the heat treatment chamber 50 is sealed and the heat treatment process is started. That is, the temperature adjustment means 52 sets the wafer W to a second processing temperature higher than the first processing temperature. In this case, the second processing temperature is, for example, 100 to 400 ° C.

  Further, the inside of the heat treatment chamber 50 is forcibly exhausted through the exhaust passage 56, and the inside of the heat treatment chamber 50 is brought into a predetermined reduced pressure state. In this case, the pressure in the heat treatment chamber 50 is set to 133 to 400 Pa (1 to 3 Torr), for example, by operating the exhaust pump 66 and adjusting the pressure controller 65.

  Then, nitrogen gas is supplied into the heat treatment chamber 50 through the supply path 55 at a predetermined flow rate. In this case, the supply amount of the nitrogen gas is adjusted to, for example, 500 to 3000 sccm by adjusting the flow rate adjusting valve 61. Thereby, the heat of the temperature adjusting means 52 built in the mounting table 51 is efficiently conducted to the wafer W, and the temperature of the wafer W is accurately controlled.

In the heat treatment apparatus 5 ′, ammonia gas is supplied into the heat treatment chamber 50 through the supply path 70 at a predetermined flow rate. In this case, the supply amount of ammonia gas is adjusted to, for example, 1000 to 3000 sccm by adjusting the flow rate adjusting valve 72. As a result of the supply of ammonia gas, the reaction product D ″ previously transformed into fluorosilicic acid (H ₂ SiF ₆ ) further reacts with ammonia to mainly produce ammonium fluorosilicate ((NH ₄ )). 2) to a reaction product comprising 2SiF ₆ ).

The reaction product thus produced (ammonium fluorosilicate ((NH ₄ ) 2 SiF ₆ )) is heated by the temperature control means 52 in the heat treatment apparatus 5 ′, and the SiF ₄ gas, NH ₃ gas, and hydrogen fluoride gas Then, it is vaporized and removed from the first resist pattern P1. Thus, as shown in FIG. 9B, only the first resist pattern P1 and the second resist pattern P2 remain on the first hard mask C on the surface of the wafer W.

  When the heat treatment is completed, first, the flow rate adjustment valve 72 is closed and the supply of ammonia gas is stopped. After the purge to the nitrogen gas is completed, the flow rate adjustment valve 61 is closed and the supply of nitrogen gas is stopped. Then, as before, the wafer W is unloaded from the load lock chamber 3 and returned to the carrier C on the carrier mounting table 11. As described above, a series of steps in the residual film removal processing system 1 is completed.

According to such a processing method, the remaining film D ′ remaining on the first resist pattern P1 can be removed from the surface of the wafer W, as before. In addition, in the heat treatment apparatus 5 ', ammonium fluorosilicate generated by the reaction of ammonia with the reaction _((NH 4) 2SiF ₆₎ is vaporized is easier than fluorosilicic acid _(H 2 SiF _6), It is considered easier to remove.

In the above description, the case where the remaining film D ′ of the second hard mask D made of, for example, a BPSG film, a BSG film, or a PSG film is removed has been described as an example. However, the treatment according to the present invention is performed using these BPSG film, BSG film, It is considered that the moisture contained in the BPSG film, the BSG film, and the PSG film is effective for removing the PSG film. That is, even if the same silicon oxide film is used, for example, the BPSG film, the BSG film, and the PSG film have a lower density than the thermal oxide film and the natural oxide film, and the water content in the film is reduced by the thermal oxidation. Higher than films and natural oxide films. As described above, the activation energy required to generate fluorosilicic acid (H ₂ SiF ₆ ) is reduced in the BPSG film, the BSG film, and the PSG film having a high water content by reaction with hydrogen fluoride. Therefore, it is thought that it is easy to react with hydrogen fluoride.

In contrast, a thermal oxide film or a natural oxide film having a relatively low water content in the film has an activity required to generate fluorosilicic acid (H ₂ SiF ₆ ) by reaction with hydrogen fluoride. It is considered that it is difficult to react with hydrogen fluoride because of high chemical energy.

Based on this theory, for example, when the target portion made of a BPSG film, BSG film or PSG film and the target portion made of a natural oxide film are exposed on the substrate surface, the activation energy decreases. Only the BPSG film, BSG film, or PSG film that has been reacted with hydrogen fluoride can be selectively transformed into fluorosilicic acid (H ₂ SiF ₆ ), and the natural oxide film can be left unreacted with hydrogen fluoride. It becomes. In this way, only the portion to be processed consisting of the BPSG film, the BSG film, or the PSG film is transformed into fluorosilicic acid (H ₂ SiF ₆ ), and then the substrate is heat treated to transform into fluorosilicic acid (H ₂ SiF ₆ ). In addition, only the portion to be processed made of the BPSG film, BSG film or PSG film can be selectively removed from the substrate surface, and the portion to be processed made of the natural oxide film can be left as it is on the substrate surface.

  In the above embodiment, the inert gas supplied as the dilution gas to the processing chamber 20 of the reaction processing apparatus 4 and the processing chamber 50 of the heat treatment apparatus 5 is nitrogen gas, but other inert gas, for example, , Argon gas (Ar), helium gas (He), or xenon gas (Xe) may be used, or two or more of argon gas, nitrogen gas, helium gas, and xenon gas are mixed. It may be a thing. It is also possible to omit the supply of inert gas.

  Further, the structure of the remaining film removal processing system 1 is not limited to that shown in the above embodiment. For example, in addition to the reaction processing apparatus and the heat treatment apparatus, a processing system including an etching processing apparatus may be used. For example, as in the processing system 90 shown in FIG. 12, a common transfer chamber 92 including a wafer transfer mechanism 91 is connected to the transfer chamber 12 via a load lock chamber 93, and around the common transfer chamber 92, A reaction processing device 95, a heat treatment device 96, and an etching processing device 97 may be provided. In the processing system 90, the wafer transfer mechanism 91 allows the wafer W to be carried into and out of the load lock chamber 92, the reaction processing device 95, the heat treatment device 96, and the etching processing device 97, respectively. The common transfer chamber 92 can be evacuated. That is, by making the common transfer chamber 92 in a vacuum state, the wafer W unloaded from the heat treatment apparatus 96 can be loaded into the etching treatment apparatus 97 without being brought into contact with oxygen in the atmosphere. Further, for example, as shown in FIG. 13, the present invention can be applied to a processing system 106 in which six processing apparatuses 100 to 105 are provided around a common transfer chamber (transfer chamber) 99. The number and arrangement of processing devices provided in the processing system are arbitrary.

In the above, the residual film D ′ on the first resist pattern P1 is transformed into a reaction product mainly composed of fluorosilicic acid (H ₂ SiF ₆ ) by a reaction treatment, and then SiF ₄ is subjected to a heat treatment performed thereafter. Although the case of removing by a so-called dry cleaning process such as vaporization as gas and hydrogen fluoride gas has been described, the remaining film D ′ on the first resist pattern P1 is subjected to so-called wet processing using an appropriate etching solution or the like. It is also possible to remove it. However, in the case of the wet etching process, there is a concern that the problem that the first hard mask C as a base is scraped or the problem of leaning due to the surface tension of the etching solution may occur. In order to avoid such a problem, it is preferable to remove the remaining film D ′ on the first resist pattern P1 by a dry cleaning process.

  Further, the film structure of the wafer W described in the above embodiments is an example, and the present invention may be applied to other film structures. In the above embodiment, the antireflection film is formed between the resist pattern and the SOG film as the base film. However, the present invention is also applied to the case where the resist pattern is formed directly on the SOG film. it can. In the above embodiment, the resist pattern forming process according to the present invention is applied to the double patterning process in which patterning is performed twice. However, the resist pattern forming process may be applied to a process in which patterning is performed three times or more. . Furthermore, the present invention can be applied not only to patterning a plurality of times but also to other substrate processing for forming a resist pattern. The present invention can also be applied to processing on other substrates such as an FPD (flat panel display) other than a wafer and a mask reticle for a photomask.

  The present invention is useful when a resist pattern is formed by double patterning.

It is a schematic plan view of the residual film removal processing system concerning embodiment of this invention. It is the schematic longitudinal cross-sectional view which showed the structure of the reaction processing apparatus. It is the schematic longitudinal cross-sectional view which showed the structure of the heat processing apparatus. It is a flowchart of the etching process using double patterning. (A) is explanatory drawing which shows the state in which the gate oxide film, the to-be-etched film, the 1st hard mask, the 2nd hard mask, the organic film, and the SOG film were formed on the wafer. (B) is explanatory drawing which shows the state in which the antireflection film and the resist film were formed on the SOG film. (C) is explanatory drawing which shows the state in which the 1st resist pattern was formed. (A) is explanatory drawing which shows the state by which the anti-reflective film and the SOG film were etched using the 1st resist pattern as a mask. (B) is explanatory drawing which shows the state by which the organic film was etched using the SOG film | membrane as a mask. (C) is explanatory drawing which shows the state by which the 2nd hard mask was etched by using an organic film as a mask. (A) is explanatory drawing which shows the state in which the organic film and SOG film | membrane of the 2nd time were formed. (B) is explanatory drawing which shows the state in which the antireflection film and the resist film were formed on the SOG film. (C) is explanatory drawing which shows the state in which the 2nd resist pattern was formed. (A) is explanatory drawing which shows the state by which the anti-reflective film and the SOG film | membrane were etched using the 2nd resist pattern as a mask. (B) is explanatory drawing which shows the state by which the organic film was etched using the SOG film | membrane as a mask. (C) is explanatory drawing which shows the state by which the 1st hard mask was etched by using an organic film and a 2nd hard mask as a mask. (D) is explanatory drawing which shows the state from which the SOG film | membrane and the organic film were removed. (A) is explanatory drawing which shows the state by which the residual film | membrane remaining on the 1st resist pattern is transformed into a reaction product. (B) is explanatory drawing which shows the state from which the reaction product was removed from the 1st resist pattern, and only the 1st resist pattern and the 2nd resist pattern remain on the 1st hard mask. It is explanatory drawing which shows the state by which the to-be-etched film was etched using the 1st hard mask as a mask. It is the schematic longitudinal cross-sectional view which showed the structure of the heat processing apparatus concerning a modification. It is a schematic plan view of the processing system concerning another embodiment. It is explanatory drawing of the processing system which provided the six processing apparatuses around the common conveyance chamber.

Explanation of symbols

P1 First resist pattern P2 Second resist pattern W Wafer 1 Residual film removal processing system 2 Loading / unloading section 3 Load lock chamber 4 Reaction processing apparatus 5 Heat treatment apparatus 6 Control computer 10 Transport mechanism A Gate oxide film B Etched film C First hard mask D Second hard mask D ′ Residual film D ”Reaction products E1, E2 Organic film F1, F2 SOG film G1, G2 Antireflection film H1, H2 Resist film

Claims (24)

A method of forming a predetermined resist pattern on a base film on a substrate surface,
Forming a first hard mask and a second hard mask on the base film on the substrate surface;
A first patterning process for transferring the first resist pattern to the second hard mask;
A second patterning process for transferring the first resist pattern and the second resist pattern to the first hard mask;
A method for forming a resist pattern, comprising: removing a remaining film of the second hard mask from the first hard mask.   The method of forming a resist pattern according to claim 1, wherein the second hard mask is a silicon oxide film.   The method of forming a resist pattern according to claim 2, wherein the silicon oxide film contains at least one of boron and phosphorus. The step of removing the remaining film of the second hard mask from the first hard mask is as follows:
The step of bringing the substrate to a first processing temperature, supplying a gas containing a halogen element, chemically reacting the silicon oxide film and the gas containing the halogen element, and transforming the silicon oxide film into a reaction product. When,
3. The step of setting the substrate to a second processing temperature higher than the first processing temperature and removing the silicon oxide film transformed into the reaction product is provided. 4. A method for forming a resist pattern according to 3. A method of forming a predetermined resist pattern on a base film on a substrate surface,
For a substrate on which a first patterning process for forming a first resist pattern on the base film and a second patterning process for forming a second resist pattern on the base film are performed in advance. And
A method for forming a resist pattern, comprising performing a residual film removal process for removing a residual film from the first resist pattern.   6. The method of forming a resist pattern according to claim 5, wherein the remaining film is a silicon oxide film.   The method of forming a resist pattern according to claim 6, wherein the silicon oxide film contains at least one of boron and phosphorus. The residual film removal treatment step includes
The step of bringing the substrate to a first processing temperature, supplying a gas containing a halogen element, chemically reacting the silicon oxide film and the gas containing the halogen element, and transforming the silicon oxide film into a reaction product. When,
Or a step of removing the silicon oxide film transformed into the reaction product by setting the substrate to a second processing temperature higher than the first processing temperature. 8. A method for forming a resist pattern according to 7.   9. The method of forming a resist pattern according to claim 4, wherein the gas containing a halogen element is a gas containing hydrogen fluoride.   10. The method for forming a resist pattern according to claim 4, wherein the step of transforming the silicon oxide film into a reaction product is performed under a predetermined reduced pressure.   The method for forming a resist pattern according to claim 4, wherein the step of removing the reaction product by heating is performed under a predetermined reduced pressure.   The method for forming a resist pattern according to any one of claims 4 and 8 to 11, wherein a basic gas is supplied in the step of removing the reaction product by heating.   The method for forming a resist pattern according to claim 12, wherein the basic gas is ammonia gas.   The method for forming a resist pattern according to claim 1, wherein the base film is a film to be etched.   15. The method of forming a resist pattern according to claim 14, wherein the etching target film is made of polysilicon or a silicon oxide film. A residual film removal processing system for removing a residual film from a resist pattern formed on a base film on a substrate surface,
A reaction treatment device that transforms the residual film into a reaction product, and a heat treatment device that performs a heat treatment on the residual film transformed into the reaction product,
The reaction processing apparatus includes a reaction processing chamber for storing a substrate, a mounting table for mounting the substrate in the reaction processing chamber and bringing the substrate to a desired temperature, and a gas containing a halogen element in the reaction processing chamber. A gas supply source to supply,
The said heat processing apparatus is equipped with the heat processing chamber which accommodates a board | substrate, and the mounting base which mounts the said board | substrate in the said heat processing chamber and makes the said board | substrate to desired temperature, The residual film removal processing system characterized by the above-mentioned.   The residual film removal processing system according to claim 16, wherein the gas containing a halogen element is a gas containing hydrogen fluoride.   The residual film removal processing system according to claim 16 or 17, further comprising an inert gas supply source for supplying an inert gas into the reaction processing chamber.   The residual film removal processing system according to any one of claims 16 to 18, further comprising a pressure reducing mechanism for reducing the pressure in the reaction processing chamber to a desired pressure.   The said heat processing apparatus is provided with the gas supply source which supplies basic gas in the said heat processing chamber, The residual film removal processing system in any one of Claims 16-19 characterized by the above-mentioned.   21. The residual film removal processing system according to claim 20, wherein the basic gas is ammonia gas.   The residual film removal processing system according to any one of claims 16 to 21, further comprising an inert gas supply source that supplies an inert gas into the heat treatment chamber.   The residual film removal processing system according to any one of claims 16 to 22, further comprising a decompression mechanism that decompresses the heat treatment chamber to a desired pressure. A recording medium on which a program that can be executed by a control computer of a processing system is recorded,
16. The recording medium according to claim 1, wherein the program is executed by the control computer to cause the processing system to perform the resist pattern forming method according to any one of claims 1 to 15.

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