CN210776175U - Combined mask - Google Patents

Abstract

The utility model provides a combined mask. The first mask and the second mask are used in a combined mode to define the graph of the alignment mark, so that the structure of the formed alignment mark is more complex and higher in precision, and when the photoetching process is executed based on the alignment mark, the alignment precision of the photoetching process is improved, and the alignment deviation of the photoetching process is reduced. And in the manufacturing process of combining the alignment mark with the semiconductor device, the performance of the formed semiconductor device can be correspondingly improved.

Description

Combined mask

Technical Field

The utility model relates to the technical field of semiconductors, in particular to combined mask plate.

Background

With the continuous development of semiconductor technology, the process nodes of semiconductor devices are continuously decreasing, and the film structures in semiconductor devices are more complicated, for which the alignment precision between the films is particularly important. Specifically, in the preparation of sequentially stacked patterned film layers, it is common to copy the pattern on each reticle into the corresponding film layer in conjunction with a photolithography process. When the photolithography process is performed, the alignment mark is generally recognized to achieve that the pattern on the current mask can be aligned with the pattern of the lower film layer.

Therefore, the alignment marks play a crucial role in the photolithography process, and the alignment deviation between the film layers can be directly influenced. Particularly, as semiconductor technology is continuously developed, the number of film layers in a device is continuously increased, and alignment deviations among the film layers are also superposed, so that the performance of the formed semiconductor device is seriously affected.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a combination mask version can be used for defining out the figure of counterpoint mark to improve lithography process's counterpoint precision.

In order to solve the technical problem, the utility model provides a combined mask plate, include:

a first mask having a first pattern formed thereon;

and the second mask is provided with a second pattern, and the second pattern is used for being combined with the first pattern to define a pattern of an alignment mark.

And, the utility model discloses in still provide another kind of combination mask version, combination mask version is arranged in the counterpoint mark district to the figure that is used for demarcating out the counterpoint mark to and still be used for demarcating out the figure of device rete in the semiconductor device district. Wherein the combinatorial reticle comprises:

the mask comprises a first mask, a second mask and a third mask, wherein a first alignment pattern is formed in an alignment mark area of the first mask, and a first device pattern is formed in a semiconductor device area of the first mask;

the second mask plate is provided with a second alignment pattern in an alignment mark area, the second alignment pattern is used for being combined with the first alignment pattern to define a pattern of an alignment mark, a second device pattern is formed in a semiconductor device area of the first mask plate, and the second device pattern is used for being combined with the first device pattern to define a pattern of a device film layer.

The utility model provides an among the combination mask version, can be used for demarcating out the figure of counterpoint mark. Namely, the pattern of the alignment mark is defined by the combination of the first mask and the second mask. Therefore, for traditional counterpoint mark, the utility model discloses in the figure of counterpoint mark that forms is more complicated and the precision is also higher to when follow-up photoetching process based on this counterpoint mark carries out, can improve promptly to counterpoint mark's identification precision reduces photoetching process's counterpoint deviation.

In addition, the combined mask is beneficial to improving the performance of the formed semiconductor device in the manufacturing process of combining the combined mask with the semiconductor device. Specifically, the same double-pattern lithography process can be used to form a device film layer and also form a registration mark, and the deviation condition of the formed device film layer can be reflected through the registration mark; and moreover, the alignment mark is also integrated with the deviation of the first photoetching process and the deviation of the second photoetching process, so that when the third photoetching process is executed based on the alignment mark, the third photoetching process can realize pattern alignment on the basis of balancing the alignment deviation of the first photoetching process and the alignment deviation of the second photoetching process, and is favorable for reducing the total deviation generated by the first photoetching process, the second photoetching process and the third photoetching process.

Drawings

FIG. 1 is a schematic structural diagram of a combined mask according to a first embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a combined mask blank according to a second embodiment of the present invention;

FIG. 3 is a schematic structural view of a combined mask according to a third embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a combined mask according to a fourth embodiment of the present invention;

FIG. 5 is a schematic structural view of a combined mask according to a fifth embodiment of the present invention;

FIG. 6 is a schematic structural diagram of a combined mask according to a sixth embodiment of the present invention;

fig. 7 is a schematic structural diagram of a combined mask blank according to a seventh embodiment of the present invention.

Wherein the reference numbers are as follows:

100A/200A/300A/400A/500A/600A-first reticle;

100B/200B/300B/400B/500B/600B-second reticle;

110A/210A/310A/410A-first line;

110B/210B/310B/410B-second line;

120A/320A-first blank area;

120B/320B-second white space region;

220A/420A-first graphics region;

220B/420B-second graphics area;

510A/610A-first patch pattern;

510B/610B-a second block pattern;

100A/200A/300A/400A/500A/500C'/600A-pattern of alignment marks.

Detailed Description

The combined mask of the present invention is further described in detail with reference to the accompanying drawings and the embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in simplified form and are not to precise scale, and are provided for convenience and clarity in order to facilitate the description of the embodiments of the present invention.

Example one

Fig. 1 is a schematic structural diagram of a combined mask blank according to a first embodiment of the present invention, as shown in fig. 1, the combined mask blank includes:

a first mask 100A, wherein a first pattern is formed on the first mask 110 (in this embodiment, the first pattern includes a plurality of first lines 110A); and the number of the first and second groups,

a second mask 100B, wherein a second pattern (in this embodiment, the second pattern includes a plurality of second lines 110B) is formed on the second mask 100B.

When the first pattern of the first mask 100A and the second pattern of the second mask 100B are combined with each other, the pattern 100C of the alignment mark can be defined.

Specifically, the combination manner of the first graph and the second graph is, for example: the second pattern and the first pattern are superposed on each other, and the superposed pattern is defined as a pattern of the alignment mark. Or, the combination of the first graph and the second graph may further be: and defining the pattern of the alignment mark by using the overlapped part of the second pattern and the first pattern.

In this embodiment, the first pattern includes a first line 110A, the second pattern includes a second line 110B, and when the first pattern and the second pattern are combined, the first line 110A and the second line 110B intersect. At this time, the first line 110A and the second line 110B may be mutually overlapped to define a cell array, so that the formed alignment mark pattern 100C is a hole array pattern; alternatively, an island array may be defined based on a portion where the first line 110A and the second line 110B overlap each other to form the pattern 100C of alignment marks.

It is to be understood that the first reticle 100A and the second reticle 100B each have a pattern area, and that the first pattern (i.e., the first line 110A in the present embodiment) is formed in the pattern area of the first reticle 100A and the second pattern (i.e., the second line 110B in the present embodiment) is formed in the pattern area of the second reticle 100B. And the shape and position of the pattern area of the first mask 100A and the pattern area of the second mask 100B are both corresponding to each other, so that when the first mask 100A and the second mask 100B are used in combination, the first line 110A and the second line 110B can intersect in the pattern areas.

Further, the first line 110A in the first reticle 100A and the second line 110B in the second reticle 100B may be perpendicular to each other or non-perpendicular to each other. For example, when the first line 110A and the second line 110B are perpendicular to each other, a plurality of holes (islands) in the defined hole array pattern (island array pattern) can be aligned in both the row direction and the column direction. Alternatively, when the first lines 110A and the second lines 110B extend non-vertically, the defined hole array pattern (island array pattern) may be arranged in a hexagonal array, for example. In this embodiment, the first line 110A and the second line 110B are illustrated as extending non-vertically.

With continued reference to fig. 1, the first reticle 100A and the second reticle 100B also each have blank regions, and the blank regions may be arranged anywhere on the reticles. In this embodiment, both the first mask 100A and the second mask 100B are blank regions embedded in the pattern regions, that is, the pattern regions surround the outer peripheries of the blank regions. Therefore, when the first mask plate and the second mask plate are used in combination, the defined pattern of the alignment mark surrounds the blank area.

Specifically, the first reticle 100A has a first blank area 120A in which the first pattern is not formed, and the second reticle 100B has a second blank area 120B in which the second pattern is not formed.

Further, the first blank area 120A of the first reticle 100A and the second blank area 120B of the second reticle 100B are identical in shape and correspond in position to each other. For example, the first blank area 120A of the first reticle 100A and the second blank area 120B of the second reticle 100B are both rectangular, circular, elliptical, or other polygonal shapes, etc. In this embodiment, a first blank area 120A of the first mask 100A and a second blank area 120B of the second mask 100B are both rectangular.

And a first blank area 120A of the first reticle 100A and a second blank area 120B of the second reticle 100B, the positions of which correspond to each other. As such, when the first reticle 100A and the second reticle 100B are used in combination, the respective positions of the first blank region 120A and the second blank region 120B overlap.

It is noted that the first clear area 120A of the first reticle 100A and the second clear area 120B of the second reticle 100B may be used to achieve mutual alignment of the first reticle 100A and the second reticle 100B. That is, the first reticle 100A and the second reticle 100B may achieve mutual alignment of patterns through one-to-one corresponding blank regions.

Optionally, at least two blank regions may be disposed in each of the first reticle 100A and the second reticle 100B. And at least two first blank areas 120A in the first reticle 100A and at least two second blank areas 120B in the second reticle 100B are arranged in a manner corresponding to each other. For example, in the present embodiment, four blank regions are provided in each of the first reticle 100A and the second reticle 100B, and the four blank regions in each of the first reticle 100A and the second reticle 100B are arranged in order along a predetermined direction.

Further, at least two first blank areas 120A in the first reticle 100A and at least two second blank areas 120B in the second reticle 100B have a one-to-one correspondence in shape and position. For example, the shape and position of the first blank region 110A arranged at the 1 st in the first reticle 100A correspond to the shape and position of the second blank region 110B arranged at the 1 st in the second reticle 100B; and the shape and position of the first blank area 110A arranged at the 2 nd in the first reticle 100A correspond to the shape and position of the second blank area 110B arranged at the 2 nd in the second reticle 100B, and so on. It should be noted that the shapes of the blank area arranged in the 1 st area and the blank area arranged in the 2 nd area may be different or the same.

Specifically, the method for forming the alignment mark using the reticle set as described above includes, for example:

a first step of performing a first photolithography process using a first reticle 100A to form a first pattern on a target layer;

and a second step of performing a second photolithography process by using the second mask 100B to form a second pattern on the target layer, and defining a pattern of an alignment mark by using the second pattern and the first pattern.

And thirdly, performing an etching process to copy the pattern of the alignment mark to the target layer, thereby forming the alignment mark in the target layer.

As described above, the method for defining the pattern of the alignment mark by using the second pattern and the first pattern includes, for example: and superposing the second graph and the first graph to define the graph of the alignment mark. Alternatively, the method for defining the pattern of the alignment mark may further include: and forming the pattern of the alignment mark by using the part of the first pattern covered by the second pattern.

In this embodiment, the first pattern includes a plurality of first lines, and the second pattern includes a plurality of second lines, so that the alignment mark of the hole array pattern or the island array pattern can be formed by adjusting the photolithography process and the etching process.

In an embodiment, when the pattern of the alignment mark is a hole array pattern, the forming method includes: firstly, a first photoetching process is performed by using a first mask 100A to form a first film layer with a first pattern on a target layer; then, a second photoetching process is directly performed by using a second mask 100B to form a second film layer with a second pattern on the target layer, at the moment, lines in the second film layer are correspondingly intersected and superposed with lines in the first film layer to define a plurality of cell array patterns, and each cell in the cell array is exposed with a part of the target layer; and then, performing an etching process to etch the part of the target layer exposed in each cell, so as to form an array of holes in the target layer, wherein the array of holes forms the alignment mark.

And when the pattern of the formed alignment mark is an island array pattern, the specific forming method thereof is, for example: firstly, a first photoetching process is performed by using a first mask 100A to form a first film layer with a first pattern on a target layer, and at the moment, a part of the target layer is exposed between adjacent lines in the first film layer; then, executing a first etching process to copy the first pattern in the first film layer into the target layer so as to form a plurality of lines in the target layer; then, a second photoetching process is performed by using a second mask 100B to form a second film layer with a second pattern on the target layer, and at the moment, a plurality of lines in the second film layer are intersected with a plurality of lines in the target layer; and then, executing a second etching process to etch the part of the line in the target layer, which is exposed to the second film layer, so as to form an island array in the target layer, wherein the island array forms the alignment mark.

Or, when the pattern of the formed alignment mark is an island array pattern, the specific forming method may further include: firstly, a first photoetching process is performed by using a first mask 100A to form a first film layer with a first pattern on a target layer; then, a second photoetching process is performed by using a second mask 100B to form a second film layer with a second pattern on the target layer, and at the moment, a plurality of lines in the second film layer are intersected with a plurality of lines in the first film layer; then, executing a first etching process to etch the part of the first film layer which is not covered by the second film layer, so that the pattern of the remaining first film layer is an island array pattern; and then, executing a second etching process to copy the residual island array pattern of the first film layer into the target layer so as to form the alignment mark.

Therefore, in the subsequent photoetching process, the pattern alignment of the upper film layer and the lower film layer can be realized based on the alignment mark of the island array pattern or the alignment mark of the hole array pattern.

Example two

The difference from the first embodiment is that in the present embodiment, the arrangement of the pattern areas and the blank areas in the first reticle and the second reticle is different. In this embodiment, the graphic area is embedded in the blank area.

Fig. 2 is a schematic structural diagram of a combined mask according to a second embodiment of the present invention, as shown in fig. 2, in the combined mask, a first mask 200A has a first pattern area 220A, and a first pattern in the first mask 200A is formed in the first pattern area 220A, which is a first line 210A formed in the first pattern area 220A in this embodiment. And the second reticle 200B has a second pattern area 220B, and a second pattern in the second reticle 200B is formed in the second pattern area 220B, i.e., in this embodiment, a second line 210B is formed in the second pattern area 220B.

Based on this, when the first reticle 200A and the second reticle 200B are used in combination, the positions of the first pattern area 220A and the second pattern area 220B overlap, and the pattern 200C of the defined alignment mark is in the pattern area. In this embodiment, a plurality of hole array patterns or island array patterns may be defined by the first lines 210A in the first pattern region 220A and the second lines 210B in the second pattern region 220B to form the alignment mark pattern 200C.

Further, the positions and shapes of the first pattern area 220A in the first reticle 200A and the second pattern area 220B in the second reticle 200B are the same in one-to-one correspondence. That is, the first pattern region 220A arranged at a predetermined position in the first reticle 200A and the second pattern region 220B arranged at a corresponding predetermined position in the second reticle are identical in shape and position. The shape of the pattern area in the first reticle 200A and the shape of the pattern area in the second reticle 200B may be, for example, a circle, an ellipse, a rectangle, or another polygon.

With continued reference to fig. 2, the first reticle 200A and the second reticle 200B each have at least two pattern areas, and the at least two pattern areas in the first reticle 200A and the at least two pattern areas in the second reticle 200B are arranged in a uniform manner. For example, in the present embodiment, the four first pattern areas 220A in the first reticle 200A and the four second pattern areas 220B in the second reticle 200B are all arranged in sequence along a predetermined direction. More specifically, the shapes and positions of the plurality of first pattern areas 220A in the first reticle 200A and the plurality of second pattern areas 220B in the second reticle 200B are the same in one-to-one correspondence.

With continued reference to fig. 2, in this embodiment, both the first reticle 200A and the second reticle 200B have a plurality of pattern areas, and the pattern areas are embedded in the blank areas. And, the first pattern area 220A in the first reticle 200A and the second pattern area 220B in the second reticle 200B are both rectangular in shape. Of course, in other embodiments, the shapes of the plurality of first pattern areas in the first reticle 200A may be different from each other as long as the first pattern area at the predetermined position in the first reticle 200A and the second pattern area corresponding to the predetermined position in the second reticle 200B have the same shape.

EXAMPLE III

The difference from the first embodiment is that, in the first embodiment, the first line in the first mask and the second line in the second mask are perpendicular to each other, so that the plurality of holes of the defined pattern of the alignment mark are aligned in the row direction and the column direction; alternatively, a plurality of islands of the defined island array pattern are aligned in both the row direction and the column direction.

Fig. 3 is a schematic structural diagram of a combined mask in a third embodiment of the present invention, as shown in fig. 3, a first line 310A in a first mask 300A extends along a horizontal direction, and a second line 310B in a second mask 300B extends along a vertical direction, based on which a pattern 300C of alignment marks defined by the first mask 300A and the second mask 300B is a hole array pattern or an island array pattern.

Of course, in other embodiments, the first lines 310A in the first reticle 300A may extend in a vertical direction and the second lines 310B in the second reticle 300B may extend in a horizontal direction.

Also, similar to the embodiment, both the first reticle 300A and the second reticle 300B in the embodiment have blank regions, and the blank regions are embedded in the pattern regions. In addition, in this embodiment, the shape and position of the first blank area 320A in the first reticle 300A correspond to the shape and position of the second blank area 320B in the second reticle 300B one to one.

Example four

The difference from the third embodiment is that in the present embodiment, the pattern areas in the first reticle and the second reticle are embedded in the blank area.

Fig. 4 is a schematic structural diagram of a combined mask according to a fourth embodiment of the present invention, and as shown in fig. 4, the first mask 400A and the second mask 400B both have at least two pattern areas, so that a plurality of hole array patterns or a plurality of island array patterns can be defined by the first pattern in the first mask 400A and the second pattern in the second mask 400B to form a pattern 400C of an alignment mark.

It will be appreciated that a first pattern area 420A in the first reticle 400A and a corresponding second pattern area 420B in the second reticle 400B may capture an aperture array pattern or an island array pattern in superimposition with each other. Therefore, in this embodiment, four hole array patterns or four island array patterns are obtained from the four first pattern regions 420A in the first reticle 400A and the four second pattern regions 420B in the second reticle 400B, respectively, to form the pattern 400C of the alignment mark.

And, in this embodiment, the first lines 410A of the first reticle 400A extend in a horizontal direction and the second lines 410B of the second reticle 400B extend in a vertical direction, such that the holes of the defined hole array pattern are aligned in both a row direction and a column direction, or the islands in the defined island array pattern are aligned in both a row direction and a column direction.

It should be noted that, in the second to fourth embodiments, the method for forming the alignment mark on the target layer by using the first mask and the second mask is the same as the method for forming the alignment mark in the first embodiment, and details are not described here.

EXAMPLE five

The difference from the above embodiment is that in the present embodiment, the first pattern of the first reticle includes a plurality of first block patterns, and the second pattern of the second reticle includes a plurality of second block patterns.

Fig. 5 is a schematic structural diagram of a combined mask according to a fifth embodiment of the present invention, and as shown in fig. 5, in this embodiment, a plurality of first block patterns 510A of a first mask 500A are aligned in a first direction, and a plurality of second block patterns 510B of a second mask 500B are also aligned in the first direction. As such, when the first pattern of the first reticle 500A and the second pattern of the second reticle 500B are combined, the plurality of first block patterns 510A and the plurality of second block patterns 510B are alternately connected in the first direction.

Continuing to refer to fig. 5, in this embodiment, a combination manner of the first graph and the second graph is as follows: the second graphic and the first graphic are superimposed on each other. That is, in the present embodiment, the plurality of first block patterns 510A and the plurality of second block patterns 510B are alternately connected in the first direction to form a chain pattern connected in series in a vertical direction for constituting the alignment mark pattern 500C.

In a further aspect, the plurality of first block patterns 510A in the first mask 500A are arranged in an array, and the plurality of second block patterns 510B in the second mask 500B are also arranged in an array, so that when the first mask 500A and the second mask 500B are used in combination, the plurality of first block patterns 510A and the plurality of second block patterns 510B can be alternately connected in a one-to-one correspondence.

Specifically, a plurality of first block patterns 510A arranged in an array in the first mask 500A are aligned in both the horizontal direction and the vertical direction; and the plurality of second block patterns 510B arranged in an array manner in the second mask 500B are also arranged in an aligned manner in the horizontal direction and the vertical direction, so that the first block patterns 510A and the second block patterns 510B can be alternately connected in the vertical direction, and the first block patterns 510B and the second block patterns 510B can be spaced from each other in the horizontal direction, so that a plurality of chain patterns can be defined, and the plurality of chain patterns are sequentially arranged in the horizontal direction.

Alternatively, the first block patterns 510A and the second block patterns 510B may have the same shape, for example, both may be circular, elliptical, rectangular, or other polygonal shapes. In the present embodiment, the shapes of the first and second block patterns 510A and 510B are both elliptical shapes, and the major axis directions of the elliptical shapes of the first and second block patterns 510A and 510B are both a first direction (i.e., a vertical direction), and the minor axis directions of the elliptical shapes of the first and second block patterns 510A and 510B are both a horizontal direction.

Of course, in other embodiments, the major axis direction of the oval shapes of the first block patterns 510A and the second block patterns 510B may also be a horizontal direction, in which case, the plurality of first block patterns 510A and the plurality of second block patterns 510B may be alternately connected in the horizontal direction to form a chain pattern connected in series in the horizontal direction.

Specifically, the method for forming the alignment mark on the target layer based on the reticle set in this embodiment includes the following steps, for example.

Step one, a first photoetching process is performed by using a first mask 500A to form a first film layer with a plurality of block patterns on a target layer;

step two, directly utilizing the second mask 500B to perform a second photolithography process to form a second film layer with a plurality of second block patterns on the target layer, wherein the plurality of second block patterns in the second film layer are alternately connected with the plurality of first block patterns in the first film layer to form a chain pattern connected in series;

and thirdly, executing an etching process to copy the chain pattern into the target layer, and further forming the alignment mark on the target layer.

EXAMPLE six

In a fifth embodiment, when the first mask and the second mask are used in combination, the first pattern and the second pattern are superimposed to define a chain pattern connected in series, thereby forming a pattern of the alignment mark. However, in this embodiment, a block array pattern may be defined based on a portion where the first pattern and the second pattern overlap each other at the connection portion, for forming the pattern of the alignment mark.

Fig. 6 is a schematic structural view of a combined mask blank according to a sixth embodiment of the present invention, and referring to fig. 6, a method for forming an alignment mark includes:

a first step of performing a first photolithography process using a first reticle 500A to form a first film layer having a plurality of block patterns on a target layer;

a second step of performing a second photolithography process using a second mask 500B to form a second film layer having a plurality of second block patterns on the target layer, wherein the second block patterns in the second film layer partially cover the first block patterns in the first film layer;

a third step of executing a first etching process to remove the part of the first block pattern exposed to the second block pattern, so that the pattern of the remaining first film layer is a block array pattern;

and a fourth step of performing a second etching process to copy the remaining block array pattern of the first film layer into the target layer to form the alignment mark (i.e., the alignment mark pattern 500C' shown in fig. 6).

EXAMPLE seven

The difference from the fifth embodiment is that, in the present embodiment, the first block pattern of the first reticle and the second block pattern of the second reticle are the same in shape, and the size of the second block pattern is different from the size of the first block pattern, so that when the first reticle and the second reticle are used in combination, an annular pattern can be defined by the first block pattern and the second block pattern.

Fig. 7 is a schematic structural view of a reticle assembly according to a seventh embodiment of the present invention, and as shown in fig. 7, a first reticle 600A has a plurality of first block patterns 610A, a second reticle 600B has a plurality of second block patterns 610B, and a plurality of first block patterns 610A and a plurality of second block patterns 610B correspond to each other in position.

Further, the arrangement of the plurality of first block patterns 610A in the first reticle 600A is the same as the arrangement of the plurality of second block patterns 610B in the second reticle 600B. In this embodiment, the plurality of first block patterns 610A in the first mask 600A are arranged in an array, and the plurality of second block patterns 610B in the second mask 600B are correspondingly arranged in an array.

As described above, the shape of the first block pattern 710A in the first reticle 600A is the same as the shape of the second block pattern 610B in the second reticle 600B, for example, the first block pattern 610A and the second block pattern 610B are both circular, elliptical, rectangular, or other polygonal shapes.

With continued reference to fig. 7, the second block pattern 610B has a smaller size than the first block pattern 610B, such that when the first reticle 600A and the second reticle 600B are used in combination, the centers of the first block pattern 610A and the second block pattern 610B coincide and the defined pattern 600C of the alignment mark can be made to be a ring-shaped pattern. In this embodiment, the first mask 600A and the second mask 600B are used to define the alignment mark pattern 600C as an annular pattern arranged in an array.

Specifically, the method of forming the alignment mark of the annular pattern includes the following steps, for example.

In the first step, a first photolithography process is performed using the first reticle 600A to form a first film layer having a plurality of block patterns on a target layer.

In the second step, a second photolithography process is performed using the second mask 600B to form a second film layer having a plurality of exposure regions on the target layer, wherein the exposure regions in the second film layer correspond to second block patterns in the second mask 600B one to one. And the exposed region of the second film layer and the block pattern in the first film layer correspond to each other in shape and position, and a central region of the block pattern is exposed from the exposed region.

A third step of executing a first etching process to remove the part exposed to the exposed area in the block pattern of the first film layer, so that the pattern of the remaining first film layer is an annular pattern;

and a fourth step of performing a second etching process to copy the remaining ring-shaped pattern of the first film layer into the target layer to form the alignment mark (i.e., the alignment mark pattern 600C shown in fig. 7).

Fig. 7 schematically shows: both the first reticle 600A and the second reticle 600B are dark-white patterns (i.e., both the first block pattern 610A and the second block pattern 610B are dark patterns formed on a transparent substrate), and based on this, when performing the first photolithography process and the second photolithography process, photoresists with opposite polarities may be used, so that the second block pattern 610B on the second reticle 600B can be copied into the second film layer in an "exposed region". In this case, it can be understood that the combination between the second pattern and the first pattern is: and defining the pattern of the alignment mark by using the non-overlapped part of the second pattern and the first pattern.

However, it should be appreciated that in other embodiments, the second block patterns in the second reticle may also be dark bottom light patterns, i.e. the second block patterns are both light patterns formed on an opaque substrate. At this time, when the first photolithography process and the second photolithography process are performed, the photoresists with the same polarity may be used to realize that the second block pattern 610B of the transparent pattern on the second reticle 600B is copied into the second film layer in the "exposed region". In this case, it can be understood that the combination between the second pattern and the first pattern is: and defining the pattern of the alignment mark by using the overlapped part of the second pattern and the first pattern.

As described in the background art, with the continuous development of semiconductor technology, the number of film layers in a semiconductor device is gradually increased, and the structure of the film layers is more complicated, and at this time, alignment deviations generated by the photolithography processes corresponding to the film layers are mutually superimposed, which greatly limits the performance of the semiconductor device. However, the alignment mark obtained by using the combined mask as described above is more complex and has higher precision than the pattern of the conventional alignment mark, thereby being beneficial to improving the recognition precision of the lithographic equipment when recognizing the alignment mark and improving the alignment precision of the lithographic process.

In addition, in the current semiconductor manufacturing technology, a dual patterning lithography technology is also widely used in the fabrication of semiconductor devices. The combined mask blank and the method for forming the alignment mark are particularly suitable for use in a double patterning lithography technique.

In particular, when a device film layer of a semiconductor device is manufactured by using a dual patterning lithography technique, two masks are generally required to implement a patterning process of the device film layer. Based on this, the combined mask as described above can be combined, and the photolithography process of the same double pattern is used to define the pattern of the alignment mark in the alignment mark region, and simultaneously define the pattern of the device film layer in the semiconductor device region. Therefore, when the patterned upper film layer is continuously formed on the device film layer subsequently, the patterning process of the upper film layer can realize the accurate alignment of the pattern of the upper film layer and the pattern of the lower film layer based on the alignment mark.

Therefore, the embodiment also provides a combined mask for defining the pattern of the alignment mark and the pattern of the device film layer, and the combined mask correspondingly comprises a first mask and a second mask.

The first mask plate is provided with a first alignment mark area, and the semiconductor device area is provided with a first device pattern. And a second alignment pattern is formed in the alignment mark area of the second mask, the second alignment pattern is used for being combined with the first alignment pattern to define a pattern of an alignment mark, and a second device pattern is formed in the semiconductor device area of the first mask, and the second device pattern is used for being combined with the first device pattern to define a pattern of a device film layer.

Specifically, the first alignment pattern is, for example, the first pattern in the above embodiment, and the second alignment pattern is, for example, the second pattern in the above embodiment, so as to define the pattern of the alignment mark in the above embodiment.

And the first device pattern and the second device pattern can be correspondingly designed according to the pattern of the device film layer. For example, when the combined mask is used to form node contacts arranged in an array in a memory, the first device pattern and the second device pattern may be lines extending along two different directions.

In an alternative scheme, the first alignment pattern and the first device pattern may have the same pattern, and the second alignment pattern and the second device pattern may have the same pattern, so that the pattern defining the alignment mark and the device film layer may have the same pattern.

The following describes a method for simultaneously forming alignment marks during patterning a device film layer by using the same double-pattern photolithography process based on the combined mask.

Specifically, the method for forming the semiconductor structure comprises the following steps.

First, a first photoetching process is carried out by utilizing the first mask plate to form a first alignment pattern in an alignment mark area of a target layer and form a first device pattern in a semiconductor device area of the target layer.

And then, performing a second photoetching process by using a second mask to form a second alignment pattern in the alignment mark area of the target layer and a second device pattern in the semiconductor device area of the target layer, wherein the second alignment pattern and the first alignment pattern define a pattern of an alignment mark, and the first device pattern and the second device pattern define a pattern of a device film layer.

And then, executing an etching process to copy the pattern of the alignment mark and the pattern of the device film layer into the target layer, and further forming the alignment mark and the device film layer in the target layer at the same time. It should be appreciated that, at this time, the material of the alignment mark and the material of the device film layer are the same, for example, the target layer is a conductive layer, and the material of the alignment mark and the material of the device film layer are both conductive materials.

And then, providing a third mask and executing a third photoetching process, wherein the third photoetching process carries out pattern alignment by identifying the alignment marks.

It should be noted that, when performing the first photolithography process and the second photolithography process, for example, by identifying a conventional alignment mark (e.g., a conventional cross-shaped alignment mark) already existing on the substrate, pattern alignment of the first photolithography process and the second photolithography process is achieved. Alternatively, when the second photolithography process is performed, the second device pattern formed by the second photolithography process may be aligned with the first device pattern formed by the first photolithography process based on the alignment pattern (e.g., the first alignment pattern) formed by the first photolithography process.

It should also be appreciated that in dual patterning lithography, it is often necessary to perform two lithography processes, limited by the current process window, and that alignment deviations may occur in each lithography process, and that after performing the first and second lithography processes, corresponding alignment deviations are superimposed on each other. Therefore, when the third photolithography process is performed, if the alignment is still performed based on the conventional alignment mark, the alignment deviation is randomly generated again in the third photolithography process, and the randomly generated alignment deviation and the alignment deviation of the first photolithography process/the second photolithography process are mutually overlapped, thereby affecting the performance of the formed semiconductor device.

However, in this embodiment, the alignment mark formed by using the dual pattern lithography technology integrates the alignment deviations generated by the first lithography process and the second lithography process, and at this time, when the third lithography process is performed based on the alignment mark, it is equivalent to realize the pattern alignment of the third lithography process on the basis of balancing the alignment deviation of the first lithography process and the alignment deviation of the second lithography process, so that the total deviation generated by the first lithography process, the second lithography process, and the third lithography process can be reduced. Accordingly, the alignment precision between the pattern formed by the third photoetching process and the pattern of the lower device film layer can be improved.

In addition, as described above, the first alignment pattern and the first device pattern may have the same pattern, and the second alignment pattern and the second device pattern may have the same pattern, so that the obtained alignment mark pattern and the device film layer may have the same pattern. At this time, the formed alignment mark can not only reflect the position offset of the device film layer generated in the preparation process thereof, but also can further deduce the pattern of the formed device film layer based on the pattern of the alignment mark, so as to monitor the formed device film layer by using the alignment mark.

It should be noted that, in the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other.

It should also be noted that, although the present invention has been described with reference to the preferred embodiments, the above-mentioned embodiments are not intended to limit the present invention. To anyone skilled in the art, without departing from the scope of the present invention, the technical solution disclosed above can be used to make many possible variations and modifications to the technical solution of the present invention, or to modify equivalent embodiments with equivalent variations. Therefore, any simple modification, equivalent change and modification made to the above embodiments by the technical entity of the present invention all still belong to the protection scope of the technical solution of the present invention, where the technical entity does not depart from the content of the technical solution of the present invention.

It should be further understood that the terms "first," "second," "third," and the like in the description are used for distinguishing between various components, elements, steps, and the like, and are not intended to imply a logical or sequential relationship between various components, elements, steps, or the like, unless otherwise indicated or indicated.

It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. It must be noted that, as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to "a step" or "an apparatus" means a reference to one or more steps or apparatuses and may include sub-steps as well as sub-apparatuses. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have the definition of a logical "or" rather than the definition of a logical "exclusive or" unless the context clearly dictates otherwise. Further, implementation of the methods and/or apparatus of embodiments of the present invention may include performing the selected task manually, automatically, or in combination.

Claims (14)

1. A combinatorial reticle, comprising:

a first mask having a first pattern formed thereon;

and the second mask is provided with a second pattern, and the second pattern is used for being combined with the first pattern to define a pattern of an alignment mark.

2. The combinatorial reticle of claim 1, wherein the second pattern and the first pattern are superimposed on each other to define the pattern of the alignment mark.

3. The combinatorial reticle of claim 1, wherein a portion of the second pattern and the first pattern that overlap each other define a pattern of the alignment mark.

4. The combinatorial reticle of claim 1, wherein the non-overlapping portions of the second pattern and the first pattern define the pattern of the alignment mark.

5. The combinatorial reticle of claim 1, wherein the first reticle and the second reticle each have clear areas, and wherein the clear areas of the first reticle and the clear areas of the second reticle correspond in shape and position to one another.

6. The reticle of claim 5, wherein the first reticle and the second reticle each have a pattern area, the pattern areas of the first reticle and the second reticle correspond in shape and position to each other, and the pattern areas are embedded in the blank areas.

7. The combinatorial reticle of claim 1, wherein the first pattern comprises a plurality of first lines and the second pattern comprises a plurality of second lines;

wherein, when the first pattern and the second pattern are combined, the first line and the second line intersect to define an aperture array pattern or an island array pattern.

8. The reticle of claim 7, wherein the first lines and the second lines are non-perpendicular such that the defined pattern of the array of holes is in a hexagonal array or the defined pattern of the array of islands is in a hexagonal array.

9. The combinatorial reticle of claim 1, wherein the first pattern comprises a plurality of first block patterns aligned in a first direction, wherein the second pattern comprises a plurality of second block patterns aligned in the first direction;

wherein, when the first pattern and the second pattern are combined, the first block patterns and the second block patterns are alternately connected in the first direction and are superimposed on each other to define a chain pattern connected in series.

10. The combinatorial reticle of claim 1, wherein the first pattern comprises a plurality of first block patterns aligned in a first direction, wherein the second pattern comprises a plurality of second block patterns aligned in the first direction;

wherein the first block patterns and the second block patterns are alternately connected in the first direction when the first pattern and the second pattern are combined, and a block array pattern is defined by a portion where the first block patterns and the second block patterns overlap each other at the connection.

11. The combinatorial reticle of claim 9 or 10, wherein the first block pattern and the second block pattern are both elliptical in shape, and wherein the major axis directions of the ellipses of the first block pattern and the second block pattern are both the first direction.

12. The combinatorial reticle of claim 1, wherein the first pattern comprises a plurality of first blocky patterns, the second pattern comprises a plurality of second blocky patterns, and a size of the second blocky patterns is smaller than a size of the first blocky patterns;

wherein when the first graphic and the second graphic are combined, the centers of the first block pattern and the second block pattern coincide to define a ring-shaped graphic.

13. A combined mask, wherein the combined mask is used for defining a pattern of an alignment mark in an alignment mark area and also used for defining a pattern of a device film layer in a semiconductor device area, wherein the combined mask comprises:

the mask comprises a first mask, a second mask and a third mask, wherein a first alignment pattern is formed in an alignment mark area of the first mask, and a first device pattern is formed in a semiconductor device area of the first mask;

the second mask plate is provided with a second alignment pattern in an alignment mark area, the second alignment pattern is used for being combined with the first alignment pattern to define a pattern of an alignment mark, a second device pattern is formed in a semiconductor device area of the first mask plate, and the second device pattern is used for being combined with the first device pattern to define a pattern of a device film layer.

14. The combinatorial reticle of claim 13, wherein the first alignment pattern is the same pattern as the first device pattern and the second alignment pattern is the same pattern as the second device pattern.

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