KR20090067922A - Exposure mask for alignment key and method for measuring alignment - Google Patents

Abstract

The present invention relates to an alignment mask exposure mask and an alignment measuring method, wherein an alignment mask is provided using an alignment mask exposure mask including a plurality of rectangular projection patterns each having the same number in a first direction and a second direction perpendicular to the first direction. By forming the key, the degree of alignment of the X-axis or the Y-axis can be measured through one alignment key. In addition, even when warpage occurs in the outer edge of the wafer, the degree of alignment of the X-axis or the Y-axis can be measured, respectively, thereby improving the overlap margin during the exposure process.

Description

Exposure mask for alignment key and alignment measurement method {EXPOSURE MASK FOR ALIGNMENT KEY AND METHOD FOR MEASURING ALIGNMENT}

The present invention relates to an exposure mask for alignment keys and an alignment measuring method. In particular, the present invention relates to an alignment key capable of measuring alignment even when warpage occurs in the wafer edge portion.

The present invention relates to an exposure mask for alignment keys and an alignment key measurement method.

In general, a lithography process for forming a desired pattern on a wafer is performed for manufacturing a semiconductor device.

The lithography process is a process of forming an etched layer and a photoresist film on a wafer, exposing and developing the photoresist film using a mask, and etching the etched layer on the wafer using a photoresist pattern. The exposure process is an important process for determining the accuracy of the semiconductor device manufacturing process.

As the lithography process is repeated, it is necessary to align the pattern formed in the previous process with the position of the pattern to be formed in the current process. This is because the mask pattern of the reticle and the wafer must be in the same position as in the previous pattern formation step so that the correct interlayer pattern can be matched and an electrical connection can be made.

Aligning such interlayer patterns is called alignment, and a pattern used as a reference for aligning is called an alignment key.

1A and 1B are layouts showing an exposure mask for an alignment key according to the prior art.

Referring to FIG. 1A, a plurality of first alignment marks 110 are provided in a grid to define an exposure mask 100 defining an alignment key. The plurality of first alignment marks 110 may be described. Are arranged side by side along the first direction.

Referring to FIG. 1B, a plurality of second alignment marks 160 are provided in a grid to define an exposure mask 150 that defines an alignment key. It is arranged side by side along a second direction which is a direction perpendicular to the first direction.

The alignment keys in the first direction and the second direction are formed on the wafer using the alignment mask exposure masks shown in FIGS. 1A and 1B, respectively.

In this case, when the wafer is warped in the first direction, the alignment cannot be measured using an alignment key formed along the first direction, and when the wafer is warped in the second direction, the first The alignment cannot be measured using the alignment keys formed along the two directions.

In the exposure mask and alignment measurement method for the alignment key according to the related art described above, if the alignment key of the grid type as described above is curved on the wafer, the interval between the alignment marks is changed according to the bending of the wafer. Therefore, it is not possible to measure the exact degree of alignment, so that the degree of overlap between layers cannot be matched, which causes a problem of deterioration of device characteristics.

According to an embodiment of the present invention, an alignment key is formed using an exposure mask for an alignment key provided with the same number of square light transmission patterns in the first direction and in the second direction perpendicular to the first direction. The degree of alignment of the axis or Y axis can be measured. In addition, when the wafer warpage occurs on the outer edge of the wafer, the alignment degree of the X-axis or the Y-axis can be measured, respectively, thereby improving the overlap margin during the exposure process, thereby improving the characteristics of the device. An object of the present invention is to provide an alignment measurement method.

The exposure mask for alignment keys and the alignment measuring method according to the present invention

A cross-shaped floodlight pattern provided at the center of the alignment,

It includes a plurality of rectangular projection patterns provided on both sides of the cross-shaped projection pattern, the projection pattern is characterized in that the same number is provided in the first direction and the second direction, respectively,

The first direction and the second direction are perpendicular to each other,

The square light transmission pattern is provided spaced apart in the first direction and the second direction,

CD (Critical Dimension) of the square light transmission pattern is 20 to 30 ㎛,

The square floodlight pattern is square,

The alignment key may be applied as an overlay vernier, an alignment key, a die fit target, or a critical bar.

In addition, the alignment measurement method

Forming an etched layer on the semiconductor substrate;

Forming a hard mask layer pattern on the etched layer by performing a photolithography process using the exposure mask of claim 1,

Etching the layer to be etched using the hard mask layer pattern as a mask to form an alignment key;

Scanning the alignment key to measure intensity;

And measuring the alignment using the intensity.

An alignment mask exposure mask according to the present invention and an alignment measuring method using the same include using an alignment key exposure mask in which a plurality of rectangular projection patterns are provided in equal numbers in a first direction and a second direction perpendicular to the first direction. By forming the key, the degree of alignment of the X-axis or the Y-axis can be measured through one alignment key. In addition, even when warpage occurs in the outer edge of the wafer, the degree of alignment of the X-axis or the Y-axis can be measured, respectively, thereby improving the overlap margin during the exposure process.

In addition, a preferred embodiment of the present invention is for the purpose of illustration, those skilled in the art will be able to various modifications, changes, substitutions and additions through the spirit and scope of the appended claims, such modifications and changes are the following claims It should be seen as belonging to a range.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

2 is a plan view illustrating an exposure mask for an alignment key according to the present invention.

Referring to FIG. 2, a cross-shaped light transmission pattern 210 is provided at the center of the alignment key, and a plurality of rectangular light transmission patterns 220 are provided at both sides of the cross-shaped light transmission pattern 210.

Here, the rectangular translucent pattern 220 is formed in a square having a horizontal and vertical CD of 20 to 30 μm, respectively.

In addition, it is preferable to have the same number in the first direction and the second direction, respectively, and the first and second directions are directions perpendicular to each other.

In addition, the rectangular light transmission pattern 220 is preferably provided to be spaced apart in the first direction and the second direction, respectively.

Here, the alignment key is applied as an overlay vernier, an alignment key, a die fit target, or a CD dimension (critical dimension bar).

3A to 3C are cross-sectional views illustrating a method of forming an alignment key using the alignment mask exposure mask shown in FIG. 2, and illustrates a cross section of a portion corresponding to X-X in FIG. 2. .

Referring to FIG. 3A, an etched layer 311, a hard mask layer 315, an anti-reflection film (not shown), and a photosensitive film (not shown) are sequentially formed on the semiconductor substrate 300.

Here, the etching target layer 311 may be formed in a stacked structure of the amorphous carbon layer 305 and the silicon oxynitride layer 310.

Next, the photosensitive film pattern 325 defining the alignment key is formed by performing the exposure and development processes using the alignment mask exposure mask shown in FIG. 2.

Referring to FIG. 3B, the hard mask layer 315 is etched using the photoresist pattern 325 as a mask to form a hard mask layer pattern 315a. Thereafter, the photoresist pattern 325 is removed.

Referring to FIG. 3C, the silicon oxynitride layer (SiON) 310 and the amorphous carbon layer 305 are etched using the hard mask layer pattern 315a as a mask to form the silicon oxynitride layer pattern 310a and the amorphous carbon layer pattern ( An alignment key 313 composed of 305a is formed.

3A to 3C, an alignment key in a first direction and a second direction (ie, an X-axis direction and a Y-axis direction) may be formed at the wafer edge.

Next, the intensity of the alignment key is measured by scanning in the X-axis direction and the Y-axis direction.

In this case, after measuring the distance between the peaks of the graph in the intensity graph measured in the X-axis direction and the Y-axis direction, the area of the alignment key is obtained using the measured distances in the X-axis direction and the Y-axis direction. Here, the alignment key measured below a predetermined area can be predicted that a warpage phenomenon has occurred on the wafer on which the alignment key is formed, and thus the alignment key is excluded from the alignment measurement.

At this time, even if warpage occurs in the X-axis or Y-axis at the wafer edge portion, the alignment is measured using the alignment marks arranged in the direction where the warpage does not occur.

For example, when the wafer edge portion is warped in the X-axis direction, the alignment key has alignment marks in the Y-axis direction where no warpage occurs because a plurality of squares are formed in the X-axis direction and the Y-axis direction. The alignment can be measured using. In this case, the alignment value measured using the alignment mark in the Y-axis direction may be applied to the X-axis direction.

On the contrary, when the wafer edge portion is warped in the Y-axis direction, alignment can be measured using an alignment mark in the X-axis direction in which the warpage does not occur.

Therefore, when the alignment is measured using the alignment key, the X and Y axes can be simultaneously measured by one alignment key, and even if warpage occurs in the wafer, alignment in the direction except the direction in which the warpage occurs is generated. Since it can measure, the overlap between layers at the time of an exposure process can be advanced correctly.

1A and 1B are layouts showing exposure masks for alignment keys according to the prior art;

2 is a layout showing an exposure mask for an alignment key according to the present invention;

3A to 3C are cross-sectional views illustrating an alignment key forming method using the alignment mask exposure mask shown in FIG. 2.

<Explanation of Signs of Major Parts of Drawings>

200: alignment key 210: cross-type floodlight pattern

220: alignment mark 300: semiconductor substrate

305: amorphous carbon layer 310: silicon oxynitride film

311: etched layer 315: hard mask layer

325: photoresist pattern 315a: hard mask pattern

Claims (7)

A cross-shaped floodlight pattern provided at the center of the alignment key; And And a plurality of rectangular transmission patterns provided on both sides of the cross-type projection pattern, wherein the rectangular projection patterns have the same number in the first direction and the second direction, respectively. The method of claim 1, And the first direction and the second direction are perpendicular to each other. The method of claim 1, The rectangular projection pattern is an alignment mask exposure mask, characterized in that spaced apart in the first direction and the second direction, respectively. The method of claim 1, The rectangular projection pattern is an exposure mask for an alignment key, characterized in that the square. The method of claim 1, CD (Critical Dimension) of the rectangular light-transmission pattern is an alignment mask exposure mask, characterized in that 20 ~ 30 ㎛. The method of claim 1, And the alignment key is applied to an overlay vernier, an alignment key, a die fit target, or a CD bar. Forming an etched layer on the semiconductor substrate; Forming a hard mask layer pattern on the etched layer by performing a photolithography process using the exposure mask of claim 1; Etching the layer to be etched using the hard mask layer pattern as a mask to form an alignment key; Scanning the alignment key to measure the intensity; And Measuring alignment using the intensity Alignment measurement method comprising a.

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