KR100564541B1 - Mask comprising overlay keies for alignment correction and method for correcting alignment of the mask using the same - Google Patents

Abstract

A mask having an overlay key for self alignment correction and an alignment correction using the same are disclosed. A mask having an overlay key in a field and a light shielding area used for alignment of a material layer initially formed on a substrate, wherein the overlay key is composed of first and second overlay keys, and the first overlay key is The second overlay key is provided at four corners of the field area, which is a light transmitting area of the mask, and the second overlay key is provided in the light blocking area around the four corners of the mask, but is provided symmetrically.

Description

Mask comprising overlay keies for alignment correction and method for correcting alignment of the mask using the same}

1 is a plan view of a mask having an overlay key for alignment correction according to a first embodiment of the present invention.

FIG. 2 is a plan view of overlapping overlay keys for alignment between exposed multiple fields on a wafer; FIG.

3 is a plan view showing displacement between fields due to field error.

4 is a plan view illustrating an overlap state of an overlay key for alignment correction when a field error exists.

5 is a plan view illustrating an overlap state of the overlay key for alignment correction when the field error is corrected.

6 to 8 are plan views of masks each including an overlay key for alignment correction according to the second to fourth embodiments of the present invention.

9 is a block diagram illustrating, in stages, an alignment correction method using a mask including an overlay key for alignment correction according to an embodiment of the present invention.

* Description of Signs of Major Parts of Drawings *

40, 60, 70, 80: Mask with overlay keys for self-alignment.

42, 61, 72, 82: light shielding area.

44, 62, 74, 84: light emitting area (field area)

50: grid.

44a, 44b: first and second light transmitting regions.

40a, 40b: first and second light blocking regions.

K1 to K8: first to eighth overlay keys.

The present invention relates to a semiconductor device mask and a mask alignment method using the same, and more particularly, to a mask having an overlay key for alignment correction and an alignment correction method using the same.

As the semiconductor device is highly integrated, the density of elements formed in the unit area of the substrate is increased. This means that the horizontal distance between the elements in the substrate is shortened. To compensate for this, the vertical height of the elements formed on the substrate is higher. In addition, as semiconductor devices become more functional and multifunctional, the number of material layers stacked on a substrate is increased.

In order for a semiconductor device to function properly, it is necessary to form elements at a predetermined position on a substrate during manufacturing. In other words, the alignment between the material layers used in the manufacture of semiconductor devices is important.

However, as described above, as the spacing between devices becomes narrower and the number of material layers stacked increases, the overall alignment margin decreases. Accordingly, various methods for reducing or correcting misalignment have been developed. However, most of the methods aim to precisely control the alignment between the upper and lower material layers rather than the correction side.

In the current manufacturing process of semiconductor devices, for this purpose, a process is performed by using a material layer initially aligned as a reference layer and arranging other material layers thereon.

However, this process progression has the following problems.

That is, in today's general device manufacturing process, a field error such as a rotational error or a skew error exists in the mask used for patterning the first material layer to be formed. In this case, it is inevitable to proceed with the process, ignoring such an error. In addition, although the field on the substrate may be distorted by the equipment error (e.g., magnification error or skew due to the tilting of the equipment) generated by the exposure equipment, the spec of the exposure equipment. You have to trust in the process. In addition, when the mask of the first formed material layer is re-manufactured, since the field of the mask may vary, the alignment reference values of the subsequent formed material layers are all changed, so that accurate and reproducible alignment results are difficult to be obtained.

Therefore, the technical problem to be achieved by the present invention is to solve the problems of the prior art described above, for the alignment correction that can minimize the alignment error of the subsequent material layer by easily found and corrected the alignment error of the material layer formed initially A mask having an overlay key is provided.

Another object of the present invention is to provide a mask alignment correction method using the mask.

In order to achieve the above technical problem, the present invention provides a mask having the following features.

That is, in a mask having an overlay key in one region for alignment of a material layer initially formed on a substrate,

The overlay key is composed of first and second overlay keys, and the first overlay key is provided at four corners of a field area that is a light transmission area of the mask, and the second overlay key is formed around four corners of the mask. Although it is provided in the light shielding area, it is provided symmetrically.

Here, the first and second overlay keys are formed at positions overlapping each other in different field areas.

According to an embodiment of the present invention, the first and second overlay keys are in the form of a box, a frame or a bar.

According to another embodiment of the present invention, the first and second overlay keys are configured in equal numbers to the field area and the light blocking area.

According to another embodiment of the present invention, the first overlay key is composed of one box shape, two boxes, but one side of two boxes are in contact with each other, or one corner of the two boxes are in contact with each other. It is done.

According to an embodiment of the present invention, the first and second overlay keys have rotational symmetry or mirror symmetry.

In order to achieve the above another technical problem, the present invention provides a mask alignment correction method that proceeds in the following order.

That is, (a) a material layer is formed on the substrate. (b) forming a first overlay key in a first field of the material layer and simultaneously forming a second overlay key in another field adjacent to the first field. (c) any selected one of the other fields adjacent to the first field. The first overlay key is formed in one field, but overlaps with the second overlay key. The second overlay key is formed in the first field, and the first overlay key is formed in the first field. Form overlap. (d) Analyze the overlapping state of the first and second overlay keys formed in the first field and the selected field and correct the alignment value such that the centers of the first and second overlay keys coincide with each other.

In this process, the first and second overlay keys are formed at four corners of the field, but symmetrically.

According to an embodiment of the present invention, the first overlay key may be formed in a box shape, a frame shape or a bar shape.

According to another embodiment of the present invention, the first overlay key is formed in the form of a box, and formed in the form of two boxes with one side in contact or in the form of two boxes with the corners in contact.

By the mask and the mask alignment method, an alignment error (for example, a rotational error or a meandering error) included in the first mask used in the manufacturing process of the semiconductor device can be corrected. In addition, the alignment error generated from the exposure equipment can be corrected. Accordingly, the wafer field region can be formed in the form of an ideal grid drawn on the wafer. Therefore, the field items of the mask used for patterning the subsequent material layer can be minimized to minimize the correction items and the correction values, thereby improving the reproducibility and the alignment accuracy. In addition, there is an advantage in that even when the first mask is revised, all the alignment reference values of the next mask to be used can be prevented from being distorted.

Hereinafter, a mask including an overlay key for alignment correction according to an embodiment of the present invention and a mask alignment correction method using the same will be described in detail with reference to the accompanying drawings.

However, embodiments of the present invention can be modified in many different forms, the scope of the invention should not be construed as limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. In the drawings, the thicknesses of layers or regions are exaggerated for clarity. In the drawings like reference numerals refer to like elements. Also, if it is stated that a layer is on the "top" of another layer or substrate, the layer may be directly on top of the other layer or substrate and a third layer may be interposed therebetween.

1 is a plan view of a mask having an overlay correction key for alignment according to a first embodiment of the present invention, and FIG. 2 is a plan view of an overlay key for alignment correction overlapping between exposed fields on a wafer. 3 is a plan view showing displacement between fields due to field error.

4 is a plan view showing an overlap state of the overlay key for alignment correction when a field error exists, and FIG. 5 is a plan view showing an overlap state of the overlay key for alignment correction when a field error is corrected, FIGS. 6 to 8. Are plan views of masks each provided with overlay keys for alignment correction according to the second to fourth embodiments of the present invention.

FIG. 9 is a block diagram illustrating a step-by-step method of correcting a field alignment error using a mask having an overlay correction key.

Referring to FIG. 1, the mask 40 including the overlay key for alignment correction according to the first exemplary embodiment of the present invention has a light shielding area 42 coated with a chromium (Cr) layer and a rectangle inside the light shielding area 42. It is composed of a light transmitting area 44 of the shape. The transmissive region 44 defines a field region on the wafer, hereinafter referred to as a field region 44.

A first overlay key K1 is formed at four corners of the field area 44. The first overlay key K1 has a rectangular first light blocking region 40a at the center thereof, and a first light transmitting region 44a is formed around the first light blocking region 40a. A second light blocking region 40b having a rectangular shape is formed around the first light transmitting region 44a. Therefore, the second light blocking region 40b is a rectangular frame having a constant width surrounding the second light blocking region 40b.

A second overlay key K2 is formed in the light shielding area 42 around the edge of the field area 44. The second overlay key K2 is configured on a diagonal line passing diagonally through the first overlay key K1. Since the light shielding area 42 in which the second overlay key K2 is formed becomes another field area in contact with the field area 44, the second overlay key K2 is in contact with the field area 44. It is configured at the edge of another field area. All of the second overlay keys K2 are light blocking regions except for the center thereof. The third light transmitting area 44b formed at the center of the second overlay key K2 is formed at a position overlapping with the first light blocking area 40a included in the first overlay key K1. In addition, an area of the third light transmitting area 44b is smaller than that of the first light blocking area 40a. Therefore, when the first and second overlay keys K1 and K2 overlap correctly, the third light transmitting area 44b of the second overlay key K2 is located inside the first light blocking area 40a. do.

The first and second overlay keys K1 and K2 shown in FIG. 1 may be in the form of a box, a frame, or a bar.

Referring to Fig. 2, reference numeral 46 denotes an area and a field of the wafer to which light passing through the transmissive area 44 of the mask 40 according to the first embodiment is exposed. The field 46a shown in the middle represents the exposed field. Small squares 48 displayed at four corners of the field 46 represent areas in which the first overlay key K1 or the second overlay key K2 is formed. As the field 46 is formed on the wafer, the first and second overlay keys K1 and K2 overlap each other at four corners of the field 46. 2 shows these results. The dotted line 50 in FIG. 2 is a grid that partitions the area of the field 46 drawn on the wafer.

If the mask shown in FIG. 1 does not include an alignment area, the field will be correctly formed along the grid 50 on the wafer. Otherwise, as shown in FIG. 3, a deformed field 52 will be formed on the wafer that does not match the grid 50.

As shown in FIG. 4, when the deformed field 52 is formed on a wafer, the first and second overlay keys K1 and K2 overlap exactly at four corners of the deformed field 52. It is in a state not to lose In other words, the second overlay key K2 is not positioned at the center of the first overlay key K1 and is biased to either side.

As shown in FIG. 4, it can be seen that the alignment error is included in the mask. In other words, it can be seen that the exposure proceeded while the mask was slightly rotated in either direction or not completely horizontal to the wafer.

If the alignment of the mask is exposed in the correct state, it can be easily seen that the result shown in FIG. 4 is generated from the alignment error included in the exposure equipment. Therefore, the result shown in FIG. 4 can be viewed, and alignment correction of the mask or the exposure apparatus can be performed.

When exposure is performed in a state where the alignment correction of the mask or the exposure equipment is completed, the result shown in FIG. 4 will be in a state as shown in FIG. 5.

Specifically, at the corners of the field 46 formed on the wafer, the first and second overlay keys K1 and K2 overlap exactly, so that the second overlay key K2 is the first overlay key K1. ) Is located in the center of the.

Next, a mask including the overlay key for alignment correction according to the second embodiment of the present invention will be described.

Referring to FIG. 6, the mask 60 including the alignment correction overlay key according to the second embodiment of the present invention has a light shielding area 61 and a field area 62 through which light formed in the light shielding area 61 is transmitted. ) Is formed. The third overlay key K3 is formed at four corners of the field area 62. The third overlay key K3 is composed of two identical box-shaped overlay keys K3a and K3b, one side of which is in contact. In other words, the third overlay key K3 is formed by pasting two first overlay keys K1 described in the first embodiment. A fourth overlay key K4 is formed in the light shielding area 61 around the edge of the field 62 of the mask 60. The fourth overlay key K4 has the same box shape as the second overlay key K2 described in the first embodiment. However, two fourth overlay keys K4 are formed around each corner of the field 62. Two fourth overlay keys K4 formed in the light shielding area 61 around the corners are formed at each side adjacent to the third overlay key K3. In detail, one fourth overlay key K4 is configured at the short side of the third overlay key K3 and the light shielding area 61 adjacent to the other, and the other fourth overlay key K4 is used. ) Is formed on the long side of the third overlay key K3 and the adjacent light shielding area 61, and among the two box-shaped overlay keys K3a and K3b constituting the third overlay key K3. The light shielding area 61 is adjacent to the overlay key K3b formed far from the side 62a of the field 62 adjacent to the short side of the third overlay key K3.

If the first and second overlay keys K1 and K2 engraved in the mask 40 according to the first embodiment are overlay keys capable of correcting alignment in the diagonal direction of the mask 40, the second embodiment will be described. The third and fourth overlay keys K3 and K4 engraved on the mask 60 are overlay keys capable of correcting alignment in two perpendicular directions, that is, X and Y directions.

Like the first and second overlay keys K1 and K2, the third and fourth overlay keys K3 and K4 may be in the form of a frame or a bar, in addition to the box. In addition, the number of the third and fourth overlay keys K3 and K4 may be one and two or more, respectively, and the third and fourth overlay keys K3 and K4 may be compatible with each other. That is, the third overlay key K3 may be configured in the light blocking area 61, and the fourth overlay key K4 may be configured at four corners of the field 62. As the field is formed on the wafer, the third and fourth overlay keys K3 and K4 overlap each other, thereby making it compatible.

Next, a mask including the overlay key for alignment correction according to the third embodiment of the present invention will be described.

Referring to FIG. 7, the mask 70 including the overlay key for alignment correction according to the third embodiment of the present invention includes a light shielding area 72 and a rectangular field area 74. A fifth overlay key K5 is formed at each of four corners of the field area 74, and a sixth overlay key K6 is formed at the light shielding area 72 around the fifth overlay key K5. have.

As can be seen from the figure, the third embodiment is consistent with the result of rotating the mask 60 according to the second embodiment by 90 ° clockwise or counterclockwise. Accordingly, the characteristics associated with the fifth and sixth overlay keys K5 and K6 correspond to those of the third and fourth overlay keys K3 and K4. However, the mask 60 according to the second embodiment is capable of multi-correction in the X-axis direction, while the mask 70 according to the third embodiment is capable of multi-correction in the Y-axis direction.

Next, a mask including the overlay key for alignment correction according to the fourth embodiment of the present invention will be described.

Referring to FIG. 8, the mask 80 including the overlay key for alignment correction according to the fourth embodiment of the present invention has a rectangular shape including a light blocking area 82 and a field area 84. Fourth overlay keys K7 are formed at four corners of the field area 84, and an eighth overlay key K8 is formed at the light shielding area 82 around the field area 84. However, the seventh and eighth overlay keys K7 and K8 have two components, respectively. That is, the seventh overlay key K7 is composed of two box-shaped overlay keys K7a and K7b with edges contacted, and the eighth overlay key K8 is used to replace the seventh overlay key k7. One overlay key and one adjacent light shielding area 82 are configured. Therefore, overlay keys K8a and K8b constituting the eighth overlay key K8 are separated. That is, two overlay keys K8a and K8b constituting the eighth overlay key K8 are formed in light shielding areas near two mutually perpendicular sides forming one corner of the field area 84. Two seventh overlay keys K7a and K7b are formed in the field area 84 adjacent to the eighth overlay keys K8a and K8b. The four corners of the field area 84 are each surrounded by two seventh overlay keys K7a and K7b. Since the two seventh overlay keys K7a and K7b are the same as each other, the corner region surrounded by the seventh overlay key K7 is one of the two seventh overlay keys K7a and K7b. 7 This is an area that can be positioned without being in contact with the overlay keys K7a and K7b. Since there are two overlay keys constituting the seventh and eighth overlay keys K7 and K8, a mask including the overlay correction key for alignment according to the fourth embodiment of the present invention is formed in the field region 84. The number of overlay keys and the number of overlay keys formed in the light blocking area 82 are the same. The description of the shape of the seventh and eighth overlay keys K7 and K8 is the same as the shape of the overlay keys disclosed in the first to third embodiments, and thus will be omitted.

Next, an alignment method using a mask having an overlay key for alignment correction according to an embodiment of the present invention will be described.

Referring to FIG. 9, the first step 90 is to form a material layer. Specifically, a material layer is formed on the substrate. The material layer is a material layer initially formed on the substrate in the manufacturing process of the semiconductor device.

The second step 92 is forming first and second overlay keys on the substrate.

Specifically, a photosensitive film is coated on the material layer. The photosensitive film is patterned using a mask provided with the above-described self-aligning overlay key. In this case, the mask includes a light shielding area and a field area (transmission area), a first overlay key is provided at four corners of the field area, and a second overlay key is provided at the light shielding area around the four corners. (See FIG. 1).

The self-aligning overlay keys respectively formed in the light shielding and field regions of the mask are aligned like the first to eighth overlay keys K1 to k8 provided in the masks according to the first to fourth embodiments of the present invention. According to the purpose, it may be formed in various forms in the field and the light shielding area. In addition, the overlay keys respectively formed in the field and the light shielding area of the mask may be formed in a box shape, but may be formed in any one selected from a frame shape and a bar shape. In this case, the first overlay key formed at the corner portion of the field region of the mask and the second overlay key formed at the light shielding region around the corner may be formed to have complementarity with each other, regardless of their shape. It is preferable.

That is, when the mask is transferred to the first field of the substrate, a first overlay key is formed at the corner of the first field and a second overlay key is formed at the light shielding area around the first field. The portion where the second overlay key is formed is a second field adjacent to the first field. The second overlay key is formed at an edge of the second field. When the mask is transferred to the second field, the first overlay key provided in the mask is a portion in which the second overlay key formed in the second field is formed in the process of transferring the mask to the first field. Is formed. On the contrary, the second overlay key of the mask is formed at a portion where the first overlay key is formed at the corner of the first field in the process of transferring the mask to the first field.

As such, the first and second overlay keys provided in the field and the light shielding area of the mask may be formed at positions overlapping each other at corners of each field while the mask is transferred to each field area of the substrate. By forming in this way, it is possible to analyze the degree of alignment of the mask by analyzing the overlapping state of the first and second overlay keys in the process of transferring the mask to each field of the substrate.

Therefore, forming the first and second overlay keys to have complementarity means that the masks are formed so that the two overlay keys overlap each other in the corner portion of the field region in the process of transferring the mask to each field region of the substrate. It means that the first and second overlay keys are formed in the field and the light shielding area of.

The material layer is patterned using the patterned photoresist as an etch mask. In other words, the first and second overlay keys provided in the mask are sequentially transferred to each field region of the material layer. As a result, the first and second overlay keys are formed to overlap each corner of the field region of the material layer.

The third step 94 is analyzing the overlapping state of the first and second overlay keys.

Specifically, it is analyzed whether the second overlay key is formed at the center of the first overlay key as shown in FIG. 5 or is biased to one side as shown in FIG. 4.

The fourth step 96 is to perform alignment correction on the mask according to the analysis result of the third step 94.

Specifically, if the second overlay key is located in the center of the first overlay key, the alignment correction of the mask may not be performed, but if the second overlay key is not located in the center of the first overlay key, It is preferable to perform alignment correction of the mask. At this time, the alignment correction of the mask should be made in the opposite direction to the second overlay key. In other words, the second overlay key is corrected to be located at the center of the first overlay key.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments, rather than to limit the scope of the invention. For example, one of ordinary skill in the art to which the present invention pertains may modify the shape of the light shielding area and the light transmitting area of the mask, or form an overlay key provided in another area other than an edge or in each area of the mask. It is apparent that the present invention can be practiced by modifying the number of overlay keys. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

 By the mask having the self-alignment correction overlay key as described above and the alignment method using the same, an alignment error (eg, rotatable error or meandering) included in the initial mask used in the manufacturing process of the semiconductor device. Erra) can be corrected. Since the alignment error that appears after the mask alignment correction is an error included in the exposure apparatus itself, it is possible to correct the alignment error of the exposure apparatus. Accordingly, the wafer field region can be formed in the form of an ideal grid drawn on the wafer. Therefore, the field items of the mask used for patterning the subsequent material layer can be minimized to minimize the correction items and the correction values, thereby improving the reproducibility and the alignment accuracy. In addition, there is an advantage in that even when the first mask is revised, all the alignment reference values of the next mask to be used can be prevented from being distorted.

Claims (11)

A mask having an overlay key in a field and a light shielding area used for alignment of a material layer initially formed on a substrate, the mask comprising: The overlay key is composed of first and second overlay keys, and the first overlay key is provided at four corners of the field area, which is a light transmitting area of the mask, and the second overlay key is around four corners of the mask. A mask having an overlay key for self-alignment correction, wherein the mask is provided in the shielding area of the mask, but is provided symmetrically. 2. The mask of claim 1, wherein the first and second overlay keys are formed at positions overlapping each other in different field regions. delete delete delete 2. The method of claim 1, wherein the first and second overlay keys respectively formed at an edge of the field area and the light shielding area around the corner are rotationally symmetrical or mirror symmetrical with respect to other neighboring edges and other overlay keys formed around the edge. And a mask having an overlay key for self alignment correction. (a) forming a material layer on the substrate; (b) forming a first overlay key in a first field of the material layer and simultaneously forming a second overlay key in another field adjacent to the first field; (c) forming the first overlay key in one of the other fields adjacent to the first field, overlapping with the previously formed second overlay key, and simultaneously forming a second overlay key in the first field Forming an overlap with the first overlay key formed in the first field; And (d) analyzing an overlapping state of the first and second overlay keys formed in the first field and the selected field and correcting an alignment value such that centers of the first and second overlay keys coincide with each other; Mask alignment method, characterized in that. 8. The method of claim 7, wherein the first and second overlay keys are formed at four corners of the field, but symmetrically. delete 8. The mask alignment method of claim 7, wherein the first and second overlay keys are formed in any one selected from the group consisting of a box, a frame, and a bar. delete

Images