JPS6319830A - Pattern for checking resolution - Google Patents

Abstract

PURPOSE:To make forms of pattern groups and conditions of resist patterns obvious by a method wherein the groups of patterns with the same size and the same shape are arranged in order in parallel and, after the groups of the patterns are developed by a photolithography process, the groups are moved linearly according to the order. CONSTITUTION:In a pattern group 111, each block is formed by 5 long rectangular patterns. In a pattern group 112, each block is constituted so as to form a quadrilateral by coupling 5 right-side-up patterns and 5 right-side-down patterns which have 45 deg. inclinations. In a pattern group 113, 5 patterns, each of which is composed of 3 rectangles which have the ratio of the areas 4:2:1, from each block. Further, in a pattern group 114, 5 long rectangular patterns form each block to constitute an order. The black patterns of the patterns 111-114 are constituted in one chip and the white patterns corresponding to the black patterns are constututed in one chip. Those chips are alternately arranged on a glass substrate in a chess-board form to constitute a mask substrate. With this constitution, as 5 patterns with the same shape and the same size are provided, the resolution of the pattern can be determined more easily.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to nine turns for resolution checking on a photomask substrate used for checking the resolution of a mask alignment device.

(Prior art) Conventionally, the mask substrate for resolution checking and setens of this type of mask alignment apparatus consists of a group of rectangular blocks arranged on a glass substrate, as shown in the original figure of Figure 2. One chip 3 is formed by a turn group consisting of a black pattern section (a section through which light does not pass) 1 and a white pattern section (a section through which light passes through) 2 as shown in FIG.

In general, the glass substrate is a glass substrate called undertime or low expansion glass, and the black turn part 1 is a metal film, which has a material and film thickness that is opaque to UV light (ultraviolet light) used in a mask alignment device. are doing.

In this way, the pattern group formed on the glass substrate 2A shown in FIG. 4 (the enlarged view is shown in FIG. 2(C)) and the Neutern group 5 (the enlarged view is shown in FIG. 2(0)) are arranged at intervals of.

The spacing is generally 150 to 200 .mu.m, and they are usually arranged on the mask substrate in an area comparable to the size of a semiconductor wafer.

The group of square turns shown in Figure 2 (4), which is a pattern on the mask board, consists of 5 long rectangular turns of the same size and forms one block (a in figure 2). Another block is formed by five long rectangular patterns whose turn widths and lengths are all smaller. In this way, Glocks are arranged in order based on size.

In this case, the large is a long rectangle/f turn with a width (8 μm) and a length of 72 μm, and instead of this turn, a proportionally reduced long rectangle/turn (for example, 6 μm x 54 μm) is divided into each block. The minimum rectangular pattern has a width of 1 μm and a length of 9 μm.

In this way, the nozoturn group is arranged in order of size from large to small blocks of five long rectangular patterns. The feature is that a long rectangle is formed with a width and length ratio of 1=9.

Such a mask substrate (hereinafter referred to as a mask substrate) having a resolution check pattern is used for pre-operation inspection or periodic inspection of the zo-turn transfer resolution (hereinafter referred to as resolution), which is the performance of the mask alignment device. The method is to coat a semiconductor wafer with a specified photoresist, expose it to ultraviolet light under the specified conditions of a mask alignment device, and develop it.
The resolution of this mask alignment device is checked by observing the developed resist pattern in which the setan has been transferred onto the semiconductor wafer.

In this case, the pattern group shown in Figure 2 is transferred and resolved, depending on the size of the pattern.

The degree of resolution varies. For example, there are patterns in which the edges of the resist are sharp, and patterns in which the boundaries are not sharp. The resolution is evaluated by observing those turns with a metallurgical microscope or measuring their dimensions with a dimension measuring device.

Generally, the magnification of a metallurgical microscope is 400 to 600 times. The normal shape and size of the photoresist pattern, the degree of development around the no-f turn, the so-called remaining parts of the resist and the parts dissolved and removed by the developer make up this pattern. The quality of the resolution can be determined by observing whether the boundaries of the resist are blurred or visible as clear lines.

However, depending on the size of the setane group, the result of the /-e turn in the resist will be different. for example.

One block of 6 μm x 54 μm has a large pattern size and is easily resolved clearly, whereas a pattern of 2 μm x 18 μm becomes thinner due to the amount of light that has passed through the thin dots and is not clearly resolved.

FIG. 3 shows this process. As shown in FIG. 3B, in order to check the resolution, a resist 3 (1-) is applied to a semiconductor wafer 31, and as shown in FIG. Exposure is performed using a partial view representatively representing a 74' turn 34 in size.

As a result of this exposure, as shown in FIG. 3C, the light P is transmitted between the exposed area 35 and the unexposed area 3 with a certain no-turn @ with respect to the surface of the resist 30 in the large-sized no-turn 33.
6 is clearly separated. Figure 3 (D) and Figure 3 IC) 8
An enlarged drawing of the section is shown. In the small size pattern 34,
Since the blocking area of the light P by the pattern is small, even if the light wraps around like the large-sized /setan 33, the unexposed part 36 will disappear or will have a small area.

Regardless of the pattern size, the light passes around at an angle Y from the corner of the cut-off pattern so that the boundary between the exposed area 35 and the unexposed area 36 becomes unclear as shown in Figure 3D). .

Furthermore, when the light that has passed through the corners of the pattern is transmitted through the photoresist 30 and reflected from the underlying mask substrate 31, this light also enters the unexposed areas and is apparently blocked by the pattern. It should be possible to make 22 lucky unexposed shots,
The actual pattern after development will be smaller.

Due to this effect, the smaller the nozzle turn, the lower the resolution will appear when exposed and imaged.Explanation in Figure 3Figure 1 explains negative photoresist, and the same applies to positive photoresist. It depends.

The above phenomenon occurs on both the short sides and the long sides of the long rectangular pattern. However, in the conventional pattern group shown in FIG. 2 (to) where the length ratio of the short side to the long side is 1 = 9, if the width (short side) is the limit of resolution, for example, 3 μm, , the long side is 27 μm, and the resist pattern after development is resolved into a long rectangle of 2 μm×26 μm, assuming that the dimension of thinning due to the wraparound of light is 0.5 μm on one side.

In this way, when a long rectangle is observed with a metallurgical microscope, it can be determined that it has resolution.

Chips (2 tan groups) are formed on the mask substrate in the shape of the substrate, but when observing resist patterns after development using a metallurgical microscope, the chips (2 tan groups) are , and preferably includes a pattern that can be determined within the field of view or in the immediate vicinity. Further, it is preferable that the observation time and the time for moving the field of view are not required.

In addition, the turns used to judge resolution are closer to the actual device turns if they are not only long rectangles.Checking the resolution using short rectangles rather than long rectangles is closer to the contact hole of the device. Therefore, judgment based on short rectangles is required, but conventionally it was not included in the pattern group.

The resolution can be checked using metallurgical microscopes, dimension measuring instruments, and electron microscopes (SEM). In particular, SEM is used to check the quality of the A-turn. Take a SEM photo.

In such a case, if the 79 turns at the dividing point are small, it is difficult to divide the check portion. This is especially difficult due to the proportional reduction and the block configuration of nine tangent groups.

In any case, the conventional pattern group is a single pattern group consisting of one type of pattern arranged in order of size, and the mask substrate used as a judgment means has a number of different pattern groups. I had to prepare one.

(Problems to be Solved by the Invention) When checking the resolution of a mask alignment device using the above-described resolution checking pattern configured on a mask substrate, the resolution can only be determined by observation with a metallurgical microscope based on long rectangles. It may not match the actual device. Therefore, the determination lacks accuracy and also takes a long time.

Further, since it is difficult to make a determination using only a mask substrate having a pattern made up of long rectangles, it takes time and effort to prepare mask substrates having other patterns and perform exposure using a mask alignment device in the same way.

However, it has the disadvantage that it requires the preparation of a mask substrate on which several types of pattern shapes are arranged, as well as the operations of exposure, development, observation, and judgment.

Furthermore, in addition to metallurgical microscopes, electron microscopy (SEM)
There were the aforementioned drawbacks when making observations.

This invention solves the problems of the prior art described above, such as the lack of observation judgment accuracy, the time required for judgment, and the ability to observe not only the metallurgical microscope but also the cross section of a pattern using an electron microscope. The present invention provides a resolution check pattern that solves the problems of the short pattern shape, which is unsuitable, and the need to prepare all mask substrates having various groups of turns.

(Means for Solving the Problems) The resolution check pattern according to the present invention has a first block in which a desired number of two or more rectangular black patterns are arranged vertically and horizontally and ordered in order of size. A second turn, which is arranged in order of size, with two or more desired number of black patterns of quadrilateral groups made by aligning the upper right and lower right patterns with a 45° inclination as one block. , 2 or more desired number of black patterns arranged in a ratio of 4 to 2 to 1 are arranged in the vertical and horizontal directions as one block, and the turn is made in the third no. , a fourth long rectangular black turn ftl block is arranged in the vertical direction, and a fourth turn is arranged in such a manner that the width of the turn and the interval between the blocks are divided into areas.

(Function) According to the present invention, since the resolution check pattern is constructed as described above, a mask substrate composed of chips each having a group of first to fourth patterns is used. The semiconductor wafer is exposed and developed in the photolithography process, and each turn of this mask substrate is transferred onto the semiconductor wafer. Each turn and the interval between patterns are measured with a measuring device, and the resolution and transfer position are determined. The exposure status is determined by determining whether the exposure is correct or not.

(Example) Hereinafter, an example of 9 turns for resolution checking of the present invention will be described based on the drawings. FIG. 1 is a cross-sectional diagram of one chip 115 on a mask substrate showing an example of the one-shot process. 101 in Fig. 1 (4) is one block of Nozo turn, 102d is the number printed on the pattern size, 103u [VJ], and the block of the pattern is in the Y direction (vertical direction) in use. 104 is the letter rHJ, indicating that the block of the pattern is in the X direction (horizontal direction). Five patterns fjr: One block is arranged in order according to its size, and the direction of each turn is parallel to X and Y, with the next turn size printed between them. Become a group.

Further, the pattern 112 is constructed by matching the upper right corner and the lower right corner with an inclination of 45'' so that one block is a quadrilateral.

Pattern 113 is a rectangular surface inside the block! JRe 4 vs 2
One block consists of five similar patterns formed at a ratio of 1 to 1, and each pattern has a total length of 5.0 μm to 1.0 μm.
Each block is arranged in a hierarchical manner with a difference of 0.2 μm up to 0 μm.

Furthermore, the pattern 114 consists of all five long rectangular patterns.
The pattern size is set at 0.2 μm increments from width 5.0 μm to 1.0 μrpN, and the length is fixed at 100 μm, arranged in an orderly manner. It is.

As mentioned above, patterns 111 to 114 constitute a 1/1 turn group, and this 1/2 turn group is shown in Figure 1 (CB).
They are arranged in a pattern on the mask substrate 101A shown in FIG. The pattern group is made up of a black pattern portion (portion through which light does not pass) 116 and a white ground portion (portion through which light passes) 117.

That is, in reality, the black and groove turns 111 to 114 are formed on one chip, and the corresponding white pattern is formed on one chip, and these steps are alternately arranged on a glass substrate in the shape of a base. The entire mask substrate is constructed by arranging them as follows.

This figure 1 (B) shows the condition in which one chip of the black pattern part and one chip of the white pattern are arranged in the shape of the base.・The white color is reversed. ・The mother turn groups 119 are arranged every other row, and the boundary between each pattern group 118 and 119 is the comrades of the respective 7917 groups 118 and 119, and this divided pattern group is chipped. The smaller the size of this chip, the smaller the amount of movement of the microscope field of view, which makes it easier to move the field of view.

The reason why one block is made up of five 74 turns as in the example above (as was the case in the conventional example) is that since there are five patterns of the same size and shape, it is possible to judge the pattern resolution more accurately. It has been made possible.

・The turn part is called a line, and the space between the pattern and the turn is called a space. It is called "line and space" and is composed of the same dimensions.

Therefore, by measuring these dimensions with a measuring device, the exposure state can be grasped. For example, if overexposure occurs, the line (pattern) iff<&.

Furthermore, the reason why the sizes of the nine turns are set to differ by 0.2 μm is that generally when photoresist is exposed and the resolution is to be checked every turn after development, a smaller value is required. This is because there is no need.

As mentioned in the conventional example above, the pattern of the photoresist is developed with dimensions changing due to the rotation of light during exposure and the reflected light. (the lower part is wider), so a relative difference of 0.2 or less is not a size value that can be distinguished.

FIG. 1(B) shows a mask substrate 101A arranged and configured from chips having the above-mentioned leans 111 to 114, and FIG. 1(C) is an enlarged view of the pattern group 118 in FIG. 1(B). Figure 1 ◎ is an enlarged view of the section group 119 in Figure 1 CB).

The mask substrate 101A shown in FIG. 1 CB) to FIG.
When a semiconductor wafer is exposed and developed in a photolithography process using the mask substrate 101A, the no-turn group of the mask substrate 101A is transferred to the semiconductor wafer.

In this case, only one mask substrate is used to transfer various pattern groups, and the pattern 111 can be used for general resolution checking. In addition to the resolution in the direction and vertical direction, it is also possible to check whether the 9 turns transferred to the semiconductor wafer imaged through the mirror of the mask alignment device are normal, even if the 9 turns are tilted upward to the right or downward to the right. It can be confirmed.

The no-turn 113 is a no-turn group with an area ratio of 4:2:1, and to check the resolution of the alignment device, the contact no-Z turn of an actual device or the fine pattern of the emitter of a high-speed bipolar IC must be It is possible to check whether the image is possible or not by checking the transfer and setting, which is closer to the actual Noreen.

This is because if the resolution of the alignment device is determined only by long rectangles/setans, fine details/setans (regular rectangular patterns) will not necessarily be resolved when the entire actual device is manufactured (see above). Figure 3 (see description of smell).

The 9-turn resolution of a semiconductor wafer is important not only when observing it from a plane using the metallurgical microscope and dimension measuring instrument, but also when the 9-turn cross-sectional shape is important in photolithography. For example, even if the appearance and dimensions are satisfied in planar observation, the final appearance and dimensions may be affected by the etching method.
Dimensions may vary.

In particular, if the cross-sectional shape of the resist pattern is such that the resist widens at the bottom, the bottom will not interfere with plasma etching using gas, resulting in a narrower final dimension.

Therefore, there is a method of photographing the cross-sectional shape using an SEM. At this time, the longer the nosoturn is, the more it is possible to divide the wafer at any point, creating a sample for observing the cross-sectional shape.

FIG. 1 (2) is a photograph of a mask substrate of one embodiment of the resolution check pattern described above, and FIG. 1 (2) is a photograph of a resist pattern in a photolithography process using the entire mask substrate.

As mentioned above, the width dimension of the e-turn is indicated by the number 121, and the number 122 representing the ratio is included.

For example, what the pattern 1 Glock 123- represents is 5.0 μm width, 4:2:1/(turn length, 20 μm, 110 μm, 5.Q μm. In this way, a long rectangle and a regular rectangle are This is a group of patterns that have both.

(Effects of the Invention) As explained in detail above, according to the present invention, setsane groups of the same size and shape are arranged in parallel, so when observing setane groups after development in the photolithography process using a metallurgical microscope. , it is possible to observe according to the hierarchy, and,
- While moving the metallurgical microscope in a straight line based on the order of the setan size, the shape of the pattern group and the symptoms of the resist pattern can be seen at a glance, making the work easier.

In addition, since it is not a pattern group of only different sizes of long rectangles like the conventional zo-turn pattern, it is used in semiconductor devices and is used for regular rectangular patterns such as contact holes or through holes.
When evaluating the resolution of a turn, using the mask substrate included in this setane group, it is possible to quickly and easily determine the resolution close to that of an actual device.

Along with this, the accuracy of understanding the performance of the mask alignment apparatus is improved, and it can be determined whether the mask alignment apparatus is compatible with the semiconductor device.

This prevents the production of products with poor resolution caused by this mask alignment device, making it difficult for photolithography to be redone during the manufacturing process and defects in electrical characteristics due to incomplete patterning of finished products, improving product yield. becomes.

Furthermore, since the turn direction on the mask substrate includes only the vertical and horizontal directions (,45@includes an inclined pattern group, there is a problem with the parallelism of the mirrors and lens groups that make up the mask alignment device. In addition, when SEM observation is required, the observation location can be easily determined by long turns.

[Brief explanation of drawings]

The moon in Figure 1 is a plan view of the pattern in one teg of the mask substrate of an embodiment of the 4-turn mask for checking the resolution of this invention. Figure 1 (C
) is an enlarged view of the black pattern group 118 in FIG. 1(CB), and FIG. 1(6) is an enlarged view of the white pattern group 119 in FIG. 1(B).
1 is an enlarged view of the part shown in FIG. The photograph, Figure 2 (4) is a plan view of a mask substrate with a conventional resolution check pattern.
Figure 2 (B) shows the shape of the base on the glass substrate as shown in Figure 2 (4).
A plan view showing a state in which mask substrates are arranged, the second
Figure (C) is an enlarged view of the /zo turn group 40 portion in Figure 2 (B). Figure 2 (to) is an enlarged view of the part of turn group 5 in Figure 2 (barrel), Figures 3 (4) to 3 (2) are
It is a figure which shows the process of exposing using the glass substrate which has the conventional resolution check pattern group in 'J Sography. 101.122 -- 1 block of pattern, l0I
A... Mask substrate, 102... Pattern width size, 111-114... Pattern, 115... One chip on mask substrate, 116... Black pattern group, 117
...White background, 118,119...Pattern group, 1
21... Number representing the width dimension of the pattern, 122...
・Numbers that represent ratios. 10/, 4 Near 77 Board 11B: Chang 0 Tashi Kun Sheep 119: tf' Tashi group +i ri □ (A) Ha0 Tashi ai' Ranu group unreceiving 1: Purchased side (B) Figure 1 Photo of the mask base placed in the non-NθFll (E) Fig. 1 12/: Noe tersi 11 inch Rem and 8tγzu number 122
1st letter 123: tF7-1st block Ov7
) Figure 1: A plan view of the 7-seg base layer of the charcoal-covered glass substrate.
) Fig. 2 f;, 2 Fig. 2 (A) owa 4σ] S 6 min 6 x 4 pin Fig. (C) Fig. 2 Z Fig. (B) Enlarged view of the addition of c> k ( D) Figure 2 Procedural Amendment (Method) October 24, 1985

Claims (1)

[Scope of Claims] (a) On one chip of a mask substrate for checking the resolution of a mask alignment device, two or more desired number of long rectangular black patterns are arranged as one block in the vertical and horizontal directions and ranked in order of size. (b) 2 or more desired number of black patterns of quadrilateral groups formed by matching the upper right pattern and the lower right pattern with a 45° inclination in the above-mentioned one chip are set as one block in order of size. (c) 2 or more desired number of black patterns arranged in a ratio of 4 to 2 to 1 in rectangular areas in one chip are arranged vertically and horizontally as one block. A resolution check pattern consisting of a third pattern arranged in order of size, and (d) a fourth pattern in which the width is changed by a fixed size in a long rectangular shape in one chip.