JP2012204453A - Forming method of wiring - Google Patents

Abstract

An object of the present invention is to provide a method of forming a wiring, which can reduce the number of steps and suppress an increase in manufacturing cost when forming a film to be processed using a sidewall transfer process.
According to the embodiment, first, a mask film 12 and a core material film 13 having a predetermined pattern are formed on a film 11 to be processed, and a spacer film 14 is formed thereon. Next, a lithography technique is applied to form a dummy spacer film 143 and a side wall pattern on the side wall of the core material film 13 so that the spacer film 14 is located within a predetermined distance from the position where the spacer film 14 is left as a mask for subsequent etching. And an etching technique. Thereafter, the core material film 13 is removed, the spacer film 14 is etched until the dummy pattern is removed, and the pattern alteration portion 21 is generated at a position where no other spacer film 14 exists in a predetermined range. Then, the pattern alteration portion 21 is removed, and the mask film 12 and the processed film 11 are etched using the spacer film 14 as a mask.
[Selection] Figure 1-6

Description

  Embodiments described herein relate generally to a wiring formation method.

  In recent years, with the miniaturization of semiconductor devices, a method for forming a pattern having a dimension exceeding the exposure resolution limit of lithography has been demanded. As one of the methods, there is known a side wall transfer process in which a side wall pattern is formed on a side surface of a core material, the core material is removed, and then an underlying film to be processed is etched using the side wall pattern as a mask.

  Since the film to be processed processed by the sidewall transfer process has a loop shape, for example, when the film to be processed is a conductive material, it must be electrically opened (opened). For this purpose, conventionally, after forming a film to be processed, a resist is applied onto the film to be processed, and a resist pattern is formed by opening a region to be loop-cut by a lithography technique, such as RIE (Reactive Ion Etching) method. The film to be processed was processed by anisotropic etching to perform loop cutting.

JP 2010-258224 A

  However, the prior art requires a separate process for performing the loop cut as described above, and there is a problem that the manufacturing cost increases due to an increase in the number of processes.

  One embodiment of the present invention provides a method for forming a wiring that can reduce the number of steps and suppress an increase in manufacturing cost when forming a film to be processed using a sidewall transfer process. The purpose is to do.

  According to one embodiment of the present invention, first, a mask film and a core material film are stacked on the film to be processed in the process film forming step, and the core material film is formed in the core material film processing step. Is processed into a predetermined pattern, and a spacer film is formed on the core film and the mask film processed into the predetermined pattern in the spacer film forming step. Next, in a resist pattern forming process, when the mask film is etched using the spacer film as a mask in a later process, a dummy resist pattern is formed within a predetermined distance from a position where the spacer film is left as the mask. . Thereafter, in the spacer film etching step, the spacer film is etched by the thickness using the resist pattern as a mask, a sidewall pattern is formed on the sidewall of the core material film, and the spacer film is formed at the position where the resist pattern is formed. A dummy pattern is formed. Next, after the core material film is removed in the core material film removal step, etching is performed until the dummy pattern of the spacer film is removed in the pattern alteration portion generation step, and the other region is within the predetermined distance range. A pattern alteration portion is generated by reacting the spacer film at a position where the spacer film does not exist with a chemical species released from the mask film by etching. Then, in the mask film etching step, the pattern altered portion is removed, the mask film is etched using the spacer film as a mask, and further, the processed film is etched using the mask film as a mask in the processed film etching step. To do.

FIG. 1-1 is a diagram schematically showing an example of a procedure of the wiring forming method according to the present embodiment (part 1). FIG. 1-2 is a diagram schematically showing an example of a procedure of the wiring forming method according to the present embodiment (part 2). 1-3 is a diagram schematically showing an example of a procedure of the wiring forming method according to the present embodiment (part 3). 1-4 is a diagram schematically showing an example of a procedure of the wiring forming method according to the present embodiment (part 4). 1-5 is a diagram schematically showing an example of a procedure of the wiring forming method according to the present embodiment (No. 6). FIGS. 1-6 is a figure which shows typically an example of the procedure of the formation method of the wiring by this embodiment (the 6). FIGS. 1-7 is a figure which shows typically an example of the procedure of the formation method of the wiring by this embodiment (the 7). FIG. 1-8 schematically shows an example of the procedure of the wiring forming method according to the present embodiment (No. 8). FIG. 2 is a top view showing an example of the arrangement of dummy patterns.

  Exemplary embodiments of a wiring forming method will be explained below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment. Further, the cross-sectional views of the wiring layers used in the following embodiments are schematic, and the relationship between the thickness and width of the layers, the ratio of the thicknesses of the respective layers, and the like may differ from actual ones. Furthermore, the film thickness and processing dimension shown below are examples, and are not limited thereto.

  FIGS. 1-1 to 1-8 are diagrams schematically showing an example of the procedure of the wiring forming method according to the present embodiment, where (a) is a plan view and (b) is an A diagram in (a). It is -A sectional drawing, (c) is BB sectional drawing of (a).

  First, as shown in FIG. 1A, on a substrate 10 such as a semiconductor substrate, a film to be processed 11 to be patterned, a mask film 12, and a core material film 13 are sequentially formed. The film 11 to be processed is, for example, a laminated structure of a tunnel insulating film, a charge storage layer, an interelectrode insulating film, and a control gate electrode film constituting a gate structure of a memory cell of a NAND flash memory, or a ReRAM (Resistive Random Access Memory). Although a stacked structure including an electrode layer, a rectifying layer, and a resistance change layer can be illustrated, a semiconductor film is processed here for the sake of simplicity. The mask film 12 serves as a mask for processing the film 11 to be processed, and also has a function as a stopper in the sidewall transfer process. As the mask film 12, for example, a DTEOS (Densified Tetra Ethyl Ortho Silicate) film having a thickness of 50 nm can be used. The core material film 13 is a film used when forming a side wall in the side wall transfer process. For example, a SiN film having a thickness of 120 nm can be used.

  Next, a resist (not shown) is applied on the core material film 13, and the resist is processed into a desired pattern by a photolithography technique. Thereafter, the core material film 13 is etched by anisotropic etching such as RIE, using the patterned resist as a mask, and the resist is removed. Here, the core film 13 is processed so as to have line patterns 131 (line and space pattern) formed at a predetermined pitch and isolated patterns 132 having a width wider than the line width of the line pattern 131. Has been.

  Further, the line pattern 131 is formed so that the upper end position decreases as it goes rightward on the paper surface. Here, each line pattern 131 has the same length, and the line pattern 131 is formed such that the upper end is positioned below the line pattern 131 on the left side by a.

  After that, as shown in FIG. 1B, the spacer film 14 which becomes the side wall of the core material film 13 is formed so as to conformally cover the substrate 10 on which the core material film 13 is formed in the side wall transfer process. . As the spacer film 14, for example, an amorphous silicon film having a thickness of 30 nm formed by a low pressure CVD (Chemical Vapor Deposition) method can be used.

  Next, as shown in FIG. 1C, a resist is applied on the spacer film 14 so as to cover a region which is not desired to be etched for protecting the core material film 13 in the next etching process by photolithography. And patterning so that the pattern of the dummy spacer film 14 remains within a predetermined distance from a portion of the spacer film 14 formed on the side wall of the core material film 13 that is not desired to be cut. , 15B. Here, a resist pattern 15A having a predetermined size and a dummy role, and a dummy resist pattern 15B are formed.

  The resist pattern 15A covers the isolated pattern 132 and is provided so that the distance d1 between the resist film 15A and the spacer film 14 formed on the side surface of the nearest line pattern 131A is within a predetermined distance range. The upper end on the paper surface is substantially the same position as the upper end of the adjacent line pattern 131A, but the lower end is shorter by a than the end of the spacer film 14 formed on the side surface of the lower end of the adjacent line pattern 131A. Is formed.

  The resist pattern 15B is provided so that the distance d2 between the resist film 15B and the spacer film 14 formed on the side surface of the nearest line pattern 131C is within a predetermined distance range, and the lower end on the paper surface is the adjacent line pattern 131C. Although it is substantially the same position as the lower end, the upper end is formed to be shorter by a than the upper end of the spacer film 14 formed on the side surface of the adjacent line pattern 131C.

  Thereafter, as shown in FIG. 1-4, the spacer film 14 is etched back by anisotropic etching such as RIE using the resist patterns 15A and 15B as a mask. As a result, the loop spacer film 141 remains so as to surround the side surface of the line pattern 131. Further, the spacer film 142 remains on the mask film 12 and the core material film 13 where the resist pattern 15A is disposed, and the spacer film 143 remains on the mask film 12 where the resist pattern 15B is disposed. The spacer film 143 is a dummy pattern.

  Next, as shown in FIG. 1-5, the exposed core material film 13 is removed. Here, since the SiN film is used as the core material film 13, the core material film 13 can be removed by hot phosphoric acid.

  Thereafter, as shown in FIG. 1-6, the skirt portion 142a of the spacer film 142 and the portion 142b on the core material film 13 formed in the etch back process of FIG. 1-4, and the spacer film 143 which is a dummy pattern are formed. It is removed by anisotropic etching such as RIE method. At this time, the state of the spacer film 14 formed as a pattern varies depending on the distance between the adjacent spacer films 141, 142, and 143. In a region where the distance between adjacent spacer films 141, 142, 143 is smaller than a predetermined value, that is, a region where a pattern is formed in a line-and-space pattern or a region where a dummy pattern is arranged, the spacer films 141, 142 , 143 as a mask, the mask film 12 is processed. On the other hand, in the region where the distance between the adjacent spacer films 141, 142, 143 is larger than a predetermined value, the chemical species released when the mask film 12 is etched reacts with the spacer films 141, 142. A product is produced. Hereinafter, the portion of the spacer films 141 and 142 where the reaction product is generated is referred to as a pattern alteration portion 21. In this case, since the mask film 12 is composed of a DTEOS film and the spacer films 141, 142, and 143 are composed of an amorphous silicon film, the amorphous silicon film is partially oxidized by the supply of oxygen from the DTEOS film, and silicon An oxide film is formed, and a pattern altered portion 21 having the same composition as the mask film 12 is generated. As a result, the pattern altered portion 21 loses its function as a mask material. As a result, the loop-shaped spacer film 141 becomes a line-shaped spacer film 141. At this time, the pattern alteration portion 21 is formed at a location where the distance between the spacer film 142 and the adjacent spacer film 141 is larger than a predetermined value.

  Whether or not the spacer films 141 and 142 are changed to the pattern altered portion 21 at the time of etching can be controlled by the distance between the adjacent spacer films 141, 142, and 143 and the width of the spacer films 141, 142, and 143. it can. For example, when the dimension (width) of the thinnest line is 30 nm or less (for example, on the order of 20 nm), if the distance between adjacent patterns is more than 100 nm to 200 nm, the spacer films 141 and 142 become the pattern altered portion. In the case of 100 nm or less, the spacer films 141 and 142 do not change.

  Next, as shown in FIGS. 1-7, the mask film 12 is etched by anisotropic etching such as RIE using the spacer films 141 and 142 and the isolated pattern 132 as a mask. At this time, the etching is performed under the condition that the mask film 12 is more easily etched than the spacer films 141 and 142. In this example, the pattern altered portion 21 is a silicon oxide film and has the same composition as the DTEOS film of the mask film 12, so that it is more easily etched than the spacer films 141 and 142. That is, the pattern altered portion 21 does not function as a mask material and is an etching target. As a result, the height of the mask film 12 at the position where the post-etching pattern altered portion 21 is formed is lower than the height of the mask film 12 at the position where the spacer film 14 is formed (FIG. 1). -7 (c)). That is, since the pattern is not transferred to the mask film 12 in the portion where the pattern alteration portion 21 is formed, the pattern of the spacer film 141 formed in a loop shape is loop-cut, and the mask film 12 is formed as a line-and-space pattern. Processed.

  Thereafter, as shown in FIGS. 1-8, the film to be processed 11 is etched by anisotropic etching such as RIE, using the mask film 12 having the loop cut pattern as a mask. At this time, since the mask film 12 having a low height does not function as a mask, a desired pattern can be transferred to the film to be processed 11. As described above, the pattern transfer process using the sidewall transfer process to the film 11 to be processed is completed.

  In the above-described example, a case where a silicon oxide film is used as the mask film 12 and a silicon film is used as the spacer film 14 is illustrated, but the present invention is not limited to this, and the spacer film 14 is used. A combination of the mask film 12 and the spacer film 14 that causes the spacer film 14 to undergo oxidation, reduction, nitridation, or other chemical reaction when the mask film 12 is etched can be formed.

  For example, in the case where a silicon nitride film is used for the mask film 12 and a silicon film is used for the spacer film 14, in a region where the distance between the adjacent spacer film 14 patterns is larger than a predetermined value, The spacer film 14 is nitrided by nitrogen released from the mask film 12 when the mask film 12 is etched, and a silicon nitride film having the same composition as the mask film 12 is generated as the pattern alteration portion 21. Then, at the time of etching the film 11 to be processed using the silicon-based spacer film 14 as a mask, the pattern altered portion 21 is removed simultaneously with the mask film 12.

  Further, when a silicon-based film is used for the mask film 12 and a silicon oxide-based film is used for the spacer film 14, in a region where the distance between the adjacent spacer film 14 pattern is larger than a predetermined value, The silicon film released from the mask film 12 during etching of the mask film 12 causes the spacer film 14 to have a silicon-rich composition, and a silicon-rich silicon oxide film is generated as the pattern alteration portion 21. Then, at the time of etching the film to be processed 11 using the silicon oxide spacer film 14 as a mask, the pattern alteration portion 21 is removed simultaneously with the mask film 12.

In addition, a silicon oxide film can be used for the mask film 12 and a film of tungsten, aluminum, titanium, or the like can be used for the spacer film 14. For example, when a tungsten film is used as the spacer film 14, oxygen released from the mask film 12 when the mask film 12 is etched in a region where the distance between the adjacent spacer film 14 patterns is larger than a predetermined value. As a result, the spacer film 14 is oxidized, and a tungsten oxide (WO _x ) film is generated as the pattern alteration portion 21. Since the pattern alteration portion 21 made of a tungsten oxide film is made of a material different from that of the silicon oxide film, the pattern alteration using a choline-based or alkali-based etchant, CF-based gas, HBr gas, or the like after the process of FIGS. A step of removing the portion 21 is added. Then, the film to be processed 11 is etched using the spacer film 14 of FIGS. 1-7 as a mask. The same applies when aluminum or titanium is used for the spacer film 14.

  In the above example, the line-and-space pattern is arranged with a predetermined distance shifted from the adjacent pattern in the extending direction of the line pattern. However, the present invention is not limited to this.

  FIG. 2 is a top view showing an example of the arrangement of dummy patterns. 2A is a top view at a step corresponding to FIG. 1-4, and FIG. 2B is a top view at a step corresponding to FIG. 1-8. In this example, as shown in FIG. 2A, a case is shown in which the line pattern 131 made of the core material film 13 is formed so that the position in the extending direction is the same in the adjacent line pattern 131. ing. A spacer film 141 is formed in a loop around the line pattern 131. When the loop cut of the spacer film 141 is performed at both ends in the extending direction of the line pattern 131, the dummy pattern is formed so as to be separated from both ends in the extending direction of the loop-shaped spacer film 141 by a predetermined distance. That's fine. In addition, the spacer film 143 which is a dummy pattern having a shorter length than the line pattern 131 is formed at both ends of the loop-shaped spacer film 141 arranged in a direction perpendicular to the extending direction of the line pattern 131 within a predetermined distance or less. May be arranged. By arranging in this way, as shown in FIG. 2B, both end portions in the extending direction of the spacer film 141 where the dummy pattern is not arranged become the pattern altered portions 21. Then, by etching the mask film 12 using the spacer film 141, both end portions in the extending direction of the spacer film 141 are automatically removed. As a result, the mask film 12 having a line-and-space pattern in which the lengths in the extending direction are uniform and the positions of the upper and lower ends in the direction perpendicular to the extending direction are aligned is formed.

  As described above, in the present embodiment, when transferring the pattern of the loop-like spacer film 14 formed by the sidewall transfer process to the mask film 12, it is between the pattern made of the adjacent spacer film 14 at the position to be cut. The spacer film 14 is processed so that the distance between the pattern made of the adjacent spacer film 14 is equal to or less than the predetermined value at a position where the distance is larger than the predetermined value and the pattern is not desired to be cut. Etching was performed after the spacer film 143) was placed. As a result, at the position on the spacer film 14 where the spacer film 14 does not exist within a predetermined distance range, the chemical species released when the mask film 12 is etched reacts with the spacer film 14 to function as a mask. The pattern alteration portion 21 that is not to be generated is generated. Then, by removing the pattern alteration portion 21, it is possible to delete the pattern only at a portion to be cut in the spacer film 14. Further, by performing processing using the spacer film 14 having such a pattern, there is an effect that a pattern having a structure that is not a closed loop can be transferred to the processed film 11 even in the sidewall transfer process.

  In addition, since a part of the closed loop pattern can be removed only by etching using the spacer film 14 as a mask, a lithography process, an etching process, and a subsequent cleaning process for cutting the closed loop pattern, which are conventionally required, are performed. It is not necessary to provide a process. That is, the number of processes can be significantly reduced as compared with the conventional case.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Substrate, 11 ... Film to be processed, 12 ... Mask film, 13 ... Core material film, 14 ... Spacer film, 15A, 15B ... Resist pattern, 21 ... Pattern alteration part, 21 ... Reaction product, 21 ... Pattern alteration part 131, 131A, 131C ... line pattern, 132 ... isolated pattern, 141, 142, 143 ... spacer film.

Claims (5)

A film formation process for forming a film by laminating a mask film and a core material film on the film to be processed;
A core material film processing step of processing the core material film into a predetermined pattern;
A spacer film forming step of forming a spacer film on the core film and the mask film processed into the predetermined pattern;
A resist pattern forming step of forming a dummy resist pattern within a predetermined distance from a position where the spacer film is left as the mask when the mask film is etched using the spacer film as a mask in a later step;
Etching the spacer film by the thickness using the resist pattern as a mask, forming a side wall pattern on the side wall of the core material film, and forming a dummy pattern of the spacer film at a position where the resist pattern is formed Process,
A core film removal step for removing the core film;
Etching is performed until the dummy pattern of the spacer film is removed, and the spacer film at a position where no other spacer film exists within the predetermined distance range is separated from the chemical species released from the mask film by etching. A pattern alteration part generation step for generating a reacted pattern alteration part; and
A mask film processing step of removing the pattern alteration portion and etching the mask film using the spacer film as a mask;
A film etching process for etching the film to be processed using the mask film as a mask;
A method for forming a wiring, comprising:   The wiring formation method according to claim 1, wherein the mask film includes a chemical species that oxidizes, reduces, nitrides, or chemically reacts with the spacer film. In the pattern altered portion generation step, the pattern altered portion is a material having a larger etching rate than the spacer film when the mask film is etched,
3. The wiring formation method according to claim 1, wherein in the mask film etching step, the removal of the pattern alteration portion and the etching of the mask film are simultaneously performed. The mask film processing step includes
A pattern alteration portion removing step of removing the pattern alteration portion by etching;
A mask film etching step of etching the mask film using the spacer film from which the pattern alteration portion has been removed as a mask;
The method of forming a wiring according to claim 1, wherein the wiring is formed. The position on the spacer film that is not desired to be removed in the resist pattern forming step is a position that is not desired to be subjected to loop cutting of the pattern of the spacer film formed in a loop around the core material film. The method of forming a wiring according to any one of claims 1 to 4.

Images