TW498425B - Method for measuring horizontal slant of image field - Google Patents

Abstract

A kind of method for measuring horizontal slant of image field is disclosed in the present invention. The dice in the image field is provided with the asymmetric integrated circuit layout pattern, which is composed of at least two pattern regions with different density. These two pattern regions with different density are the first pattern region and the second pattern region that has a lower density than the first pattern region. The invented method contains at least the following steps. At first, energy is added and focused on the entire dices in the image field. Then, the scanning electronic microscopic (SEM) image of the first pattern region or the second pattern region in the image field is taken. After that, the outline of SEM image is analyzed in order to obtain the focus difference in between the first pattern regions of the first sampling dice and the second sampling dice along the asymmetric layout pattern direction of dice in the image field. All the first pattern regions and the second pattern regions in the direction are arranged in a straight line. The distance between two of the first pattern regions is measured. A ratio value of the focus difference to the distance is then calculated; and the ratio value is the horizontal slant of the image field. After that, the horizontal slant direction of the image field is located. The horizontal slant direction of the image field can be found by using the right-hand spiral principle, in which the pointing direction of four straight fingers of right palm is the same as the direction that points from the first sampling dice toward the second sampling dice, and the palm center is pointed toward the bottom portion of dice. If the horizontal slant of the image field is a positive value, then the horizontal slant direction of the image field is the bending direction of four straight fingers toward the back of palm. If the horizontal slant of the image field is a negative value, then the horizontal slant direction of the image field is the bending direction of four straight fingers toward the center of palm.

Description

498425 V. Description of the invention (1) Field of the invention: The present invention relates to a method for measuring the horizontal inclination of an image field, in particular to an image field level for measuring a crystal grain containing an asymmetric integrated circuit layout pattern. Tilt method. BACKGROUND OF THE INVENTION: Intergated circuit (1C) chips, which are on the market, are usually made by dicing and packaging of dice. The manufacturing process of the die is to use the integrated circuit manufacturing process. On the semi-conductor wafer, a plurality of die are formed at the same time, each of which contains an integrated circuit. In addition, the photolithography process is a very important step in the semiconductor process. The principle of lithography is mainly: coating a photosensitive material (so-called photoresist) on a semiconductor wafer, and then transmitting the pattern on the photomask to the semiconductor wafer by transmitting light through a photo mask. on. Usually half of the integrated circuit is completed, and many photomasks are used to perform multiple lithography steps. Therefore, the degree of difficulty of the process can also be determined by the number of photomasks or lithography steps used. In the lithography process, the most important thing is how to accurately transfer the pattern on the photomask to the semiconductor wafer. Generally, in the lithography process, at least one crystal grain can be integrated in one image field (f i e 1 d) at a time, and one

Page 5 498425 V. Description of the invention (2) The photomask is lithographically exposed to all the crystal grains in this image field at the same time. According to the mask pattern transfer analysis of the lithography process (this can be observed with a scanning electron microscope (SEM) instrument), it can be found that when lithography exposure is performed on all the crystal grains in a certain image field, if this The layout pattern on each die in an image field is a symmetrical pattern (that is, the pattern density of any layout area on the die is approximately the same), and then it is transferred to each die after the lithography process is performed. The photoresist pattern will be similar to the desired ideal pattern. Therefore, after the subsequent etching process using this photoresist pattern as an etching mask, the film layer directly under the photoresist protected by the photoresist will not be affected. Eroded. bh is only the grain domain on the map of the large-scale densely packed case. The grains of the grain domain are arranged in a single pattern. Each grain in the field is like a grain, and this is also 5 Γ \. The grain system aa is small and heartless, and the progress of the area is dense in the map's degree. The area is high and the area is dense and the side is low. The area on the left is the same as the right and the same as above. On the grain, some of the grains as and crystal m will be {The case angle of the curtain picture under the cover to block the left engraved light field erosion of the image as the case bitmap sun block its light, especially C, with more continuation and even after The difference in this case is due to the picture, imagination} It is very reasonable, the last phase of the difference period is different. The original layer of the film layer is set to the first square and the light of the crystal is resisted. As a precautionary measure, the light is prevented from causing the quilt, and later, the process is used to make an etch quilt. # 能 大 之 更新} The case of Dr. 〇 for the distance from the rod to the ns figure is not the e 5 round of the § clothed in the grain 1 6 to the crystal V 6 is not 1 from the C is the device to be measured BB master Feeling, flat question 5 Shaoqiu 5 «In the sound of the true film field loss will be like the light case as the exposure picture due to the profile guide on the micro cloth

Page 6 498425 5. The function of invention description (3)), which causes the horizontal sensor to mistakenly think that the crystal grains are in a non-horizontal state (that is, tilted). In this way, it is mistaken for the crystal grains to be in a horizontal state. The lithography exposure process performed will result in poor focus when the image field is exposed (that is, a defocus phenomenon), which will cause the photoresist contour and the photoresist on each crystal grain to the left of the image field to be transferred. The ideal photoresist ideal contours are very different, so how to measure the horizontal tilt of the image field caused by the asymmetric layout pattern on at least one crystal grain in the image field to adjust the position of the crystal grains to a horizontal state, thereby avoiding occurrence The problem of lithographic exposure distortion will be a very important issue. The general description of the project's granularity and oblique case is shown in the figure. The water bureau field layout image of the road test volume is used to clarify the content of the document. The solution of the photoresist exposure in the round of the real-field apocalypse of Fazhi was decisively resolved. In this case, the scale of the square cloth in the picture was placed on a piece of water on a non-flat surface. Ask a question and ask less about this problem. The plan of the area where the group method is used is oblique and flat. The density of the field is similar to that of a small number of species. The infield image is the same as the second one in the plot, the second is the density, and the second is the density: This area is a step by step, and the plan is as follows. The map contains a small amount of roads and electricity. The product of the body area is referred to as the one on page 7 of 498425. V. Description of the invention (4) First, apply energy-focus to all the grains in this image field. Then, a scanning electron microscope (SEM) image of the first pattern region or the second pattern region in the image field is captured. Then analyze the profile of the scanning electron microscope image to find the first pattern interval or the first pattern interval of the first sampled grain and the second sampled grain of the image field along the direction of the asymmetric layout pattern of the grains. The focus gap between the two pattern sections, in which all the first pattern areas and the second pattern areas in this direction are aligned in a straight line, and the focus gap refers to the younger one pattern area (or the younger two pattern area) ) Minus the difference between the focus degree of the first pattern area (or the second pattern area) of the second sampling die. Then measure the distance between the two first pattern sections or the two second pattern sections. Then calculate the ratio of this focus gap to the distance, where this ratio is the horizontal tilt of the image field. Then find out the horizontal tilt direction of the image field, where the horizontal tilt direction of the image field can be found using the right-hand spiral rule, and the right-hand spiral rule is to point the palm of a right palm with the thumb and the four fingers straight. Vertical, and the four fingers pointing in the same direction as the first sampling grain toward the second sampling grain, and the palm of the right palm is pointing to the bottom of the grain. The value of the horizontal tilt of the field is positive or negative. If the value of the horizontal tilt of the image field is positive, the direction of the horizontal tilt of the image field is straightened with four fingers pointing towards the back of the palm of the right palm. If the value of the horizontal tilt of the image field is negative, then the direction of the horizontal tilt of the image field is straightened with four fingers pointing towards the palm of the right palm.

498425 V. Description of the invention (5) Direction of bending. The invention proposes another method for measuring the horizontal inclination of an image field, wherein the crystal grains in the image field have at least two asymmetric integrated circuit layout patterns composed of pattern regions with different densities, and the two patterns with different densities The region is a first pattern region and a second pattern region having a lower density than the first pattern region. The method includes at least the following steps: measuring the height of the first pattern region in the image field minus the second pattern The height difference of the zones. Then measure the length of this image field along the direction of the asymmetric layout pattern of the crystal grains, where all the first pattern areas and the second pattern areas in this direction are arranged in a line. Then find a correction parameter to correct the horizontal tilt of the image field, where the value of the correction parameter contains 0 and 1 and is between 0 and 1, and the value of the correction parameter is in the same direction as the image field. The number of grains is inversely proportional, and the value of this correction parameter is related to the number of grains in this image field in this direction. The size of this image field can be fixed by using this image field in this direction. This image field horizontal tilt analysis is obtained from different grain numbers. The ratio of this height difference to this length is then calculated. Then calculate the product of this ratio and this correction parameter, where this product is the horizontal tilt of the image field. Then find out the horizontal tilt direction of the image field, where the horizontal tilt direction of the image field can be found using the right-hand spiral rule, and the right-hand spiral rule is to point the palm of the right palm and the thumb to 498425. ) And the four fingers pointing straight are perpendicular, and the direction of the four fingers pointing is the same as the direction of the first pattern area toward the second pattern area, and the palm of the right palm points to the bottom of the die, as for this image The horizontal tilt direction of the field is related to the positive or negative value of the horizontal tilt of the image field. If the value of the horizontal tilt of the image field is positive, the horizontal tilt of the image field is straightened with four fingers towards the right palm. The back of the palm points in a curved direction, and if the value of the horizontal tilt of the image field is negative, the direction of the horizontal tilt of the image field is straightened with four fingers pointing in the direction of the bend of the palm of the right palm. If the number of grains in the image field in this direction is 1, 2, 3, 4, 5 respectively, the value of the correction parameter is about 0 · 9 6 ~ 1 (preferably about 1) , 0 · 6 4 to 0 · 6 8 (preferably about 0 · 6 6), 0 · 3 2 to 0 · 3 6 (preferably about 0 · 3 4), 0 · 1 4 to 0 · 1 8 (preferred value is about 0.1 6), 0.04 to 0.08 (preferred value is about 0.06). Explain in detail that the grain size of the image to the square is one of the oblique cases. The flat plan view of the exposure bureau ’s field layout micro-images determines the electrolytic volume to determine the product volume. The internal adjustment of the state of the state is smooth and the cost is juxtaposed according to the cost. The map of the light guide of the true missing gallery wheel of the law field is said to be μρ $. One less question

Page 10 498425 V. Description of the invention (7) The causes that cause the crystal grains to be in a non-horizontal state (that is, tilted) in the image field include the type of integrated circuit layout (that is, symmetrical or asymmetric), manufacturing process Methods (such as chemica 1 mechanical polishing (CMP) or spin-on g 1 ass (S 0 G), distribution of crystal grains in the image field, etc.) The present invention is to perform a quantitative research on the causes that cause the crystal grains in the image field to be in a non-horizontal state (that is, tilt occurs) to find out the measuring method of the image field inclination. Among them, a preferred implementation according to the present invention For example, the proposed image field tilt measurement method includes the following steps: First, all the grains in the image field are subjected to a so-called energy-focus matrix experiment and a scanning electron microscope (scanning electron microscope) is used. Electron microscope (SEM) instruments take SEM images of high-density patterns and low-density patterns in the image field. Then by comparing the contours of the SEM images, an asymmetric layout of the grains in the image field can be obtained The focus gap between any two specific high-density pattern areas in the direction (f ocusdifference). After analysis, it can be known that the tilt of the image field is equal to this focus difference divided by the distance between the two specific high-density pattern areas. For further explanation, please refer to Figure 1.

Figure 1 shows a grain with 2 X 3-first grain 1 0, second grain 1 0 2, third grain 1 0 3, fourth grain 1 0 4, fifth grain 1 0 5, the sixth grain 106 distributed image field 1 0 0, which has two grains viewed from the X direction, and three grains viewed from the y direction (the definition of direction here is based on Xi Known right-angle coordinate system, where the xy plane is the plane in which Figure 1 is located, and the X, y, and z directions are shown in Figure 1), and the distribution of each grain

Page 11 498425 V. Description of the invention (8) The local pattern is asymmetric in the X direction (that is, each grain has a high-density layout pattern area and a low-density layout pattern area as shown in FIG. 1-the first grain 1 0 1 has a first high-density layout pattern region 101 a and a first low-density layout pattern region 1 0 1 b, and the second die 1 0 2 has a second high-density layout pattern region 1 〇 2 a and a second low-density layout pattern The region 1 0 2 b, the third crystal grain 103 has a third high-density layout pattern region 1 0 3 a and the third low-density layout pattern region 1 0 3 b, and the fourth crystal grain 104 has a fourth high-density layout. The pattern region 104 a and the fourth low-density layout pattern region 104 b and the fifth die 105 have a fifth high-density layout pattern region 105 a and a fifth low-density layout pattern region 105 b and a sixth die 10 6 has a sixth high-density layout pattern region 106a and a sixth low-density layout pattern region 106b). Therefore, the calculation of the image field tilt can be divided by the focus difference between the first high-density layout pattern area 1 0 1 a and the second high-density layout pattern area 1 0 2 a by the first high-density layout pattern area 101 a And the distance from the second high-density layout pattern area 102a. That is to say, the image of the high school field of the high degree of difference is similar to that of the electric field of the C body. The field image of the small body of the C product is not the same. Depending on the situation, there is a slope difference in the crystallinity of this fragment- -The appearance of the high-angle oblique field of the dip field is based on the image of the scene: Can be distributed, Lugong's step-by-step measurement of the measured product's derivative can be closely related to the oblique field. The image is divided into small and large borrowed fields to advance into the image. It is indistinguishable from the electric circuit volume of the Guantu Bureau / (V crystal / field number, see C. The main cloth is called fcr ¥ 晶晶 着The difference in the height of the X along the midfield image is 7 square heights _ of the-the case plan and the value is good, the value of the trial and error has been corrected and tested to {φ shell, there are several relationships With reference to Zheng Buxiu, the content of the crystals on the grains is described separately. The medium field length is shown on page 12 498425 V. Description of the invention (9) Please refer to Figure 2. According to Figure 2, if the crystals contained in the image field The grain distribution is shown in Figure 1 (that is, the image field has 2 × 3 grains, and the layout of each grain contained in the image field Is asymmetric in the X direction), the value of the correction parameter is 0.66. Now taking the image field shown in Figure 1 as an example, the calculation of the image field inclination is as follows: For the calculation of the image field inclination, you can use the first The height difference between the high-density layout pattern area 1 0 1 a and the first low-density layout pattern area 1 0 1 b is first multiplied by the correction parameter (its value is known as 0.6 in Figure 2), and then divided by Figure 1. The length of the image field 100 along the X direction is obtained. For a more detailed explanation of the image field inclination formula derived above, please refer to Figure 3 (the direction definition here and the direction definition described in Figure 1 The same), wherein FIG. 3 shows the first high-density layout pattern area 101a, the first low-density layout pattern area 101b, the second high-density layout pattern area 102a, and the second low-density layout pattern area 102b in FIG. Relative height and position. From Figure 3, it can be seen that the surface of the image field 100 is tilted by an angle w because the layout pattern of the crystal grains contained in it is asymmetric. In addition, the first height The height difference between the density layout pattern region 101 a and the first low density layout pattern region 1 0 1 b is approximately Is Η, and the length along the X direction in the image field 100 is L. And the applicable correction parameter value for this image field is 0.66. Therefore, it can be seen from Figure 3 that the image in the image field 100 The field inclination W is similar to the arc length formula of the sector, which is equal to (HxO. 66) / (L). After the image field inclination is calculated, the crystal field inclination can be calculated based on the calculated image field inclination. The image field is adjusted horizontally.

Page 13 498425 V. Description of invention (ίο) The basis of the calculated image field tilt (stepper job), which is used to sense the overall level of the image field (the horizontal state (this is called). That is, the image field The adjustment of the wafer to a horizontal and flat state depends on the level. If the full-scale shadow exposure is completed, the image field distortion caused by grains will be caused. Therefore, the image field adjustment state is relied on in a step by step. The position of the microcrystal before the leveling process ¾ is in the light of Cheng Ranxing, and the water light 1 light is called d. The case is away, Cheng Ping. The sense of exposure is that the field is adjusted after the field is illuminated. Camera ^ film C field el) The image has been adjusted as the exposure was suddenly adjusted to 1 micro state. The image eve will measure whether the film has been moved in step W and 1 is the sensor that has been slightly adjusted. 6 The circular-path electrical modulation is the sensor, the field water} el, the crystal is the body's hair, and the field is OK. 1 Test: The image is measured before the f, the product will be flat and the image will be sensed. We call the water and degree field level to the water level, and the water level is equal to the water level. The water level is measured from the flat-field exposure field to the non-topic surface water. Whole question field Η Pingjing 11 field micro-parallel oblique circle flat image to lose 1 image of a line of water, the crystal water is tilted to the degree of ◦ is the state measurement plane Heisei device oblique description of the g before the sense of water An implementation example of the above-mentioned level sensor's sensing of the image field level can be explained with reference to FIG. 4. As shown in FIG. 4, on an image field 200 coated with photoresist, four horizontal sensing areas near the corners are defined-the first horizontal sensing area 200a, and the second horizontal sensing area. 2 0 0 b, the third horizontal sensing area 2 0 0 c, and the fourth horizontal sensing area 2 0 0 d. Then emit light to the four horizontal sensing areas, and use a horizontal sensor to receive and analyze the light reflected from the four horizontal sensing areas to find the height of the four horizontal sensing areas in the z direction. Then the height of the four horizontal sensing areas in the z direction can be divided into

Page 14 498425 V. Description of the invention (11) Whether the precipitation image field has been adjusted to a horizontal state. In addition, Figure 5A and Figure 5B are used to further explain how to adjust the image field where the crystal grains are located according to the calculated image field inclination. (The directions in Figure 5A and Figure 5B are defined as described in Figure 1. The direction is the same). As shown in FIG. 5A, it indicates that if the layout pattern of the crystal grains in the image field is asymmetric in the X direction and the image field inclination is positive, as long as the right thumb is pointed in the y direction and the other four fingers are pointed in X Direction, and then rotate the above-mentioned image field inclination in the direction that the four fingers are bent downward, and the image field where the crystal grains are located can be adjusted to a horizontal state. The direction definition of this method is the same as the conventional right-handed spiral rule. Of course, if the layout pattern of the crystal grains in the image field is asymmetric in the X direction and the image field tilt is negative, then just point the right thumb to the y direction and The other four fingers point in the X direction, and then rotate the above-mentioned image field inclination along the upward direction of the four fingers to adjust the image field where the crystal grains are located to a horizontal state. Similarly, as shown in FIG. 5B, it is pointed out that if the layout pattern of the crystal grains in the image field is asymmetric in the y direction and the image field inclination is positive, as long as the right thumb is pointed in the X direction and the other four Point the finger to the y direction, and then rotate the image field inclination in the direction that the four fingers bend down to adjust the image field where the crystal grains are located to a horizontal state. The direction definition of this method is the same as the conventional right-handed spiral rule. Of course, if the layout pattern of the crystal grains in the image field is asymmetric in the y direction and the image field tilt is negative, just point the right thumb to the X direction and The other four fingers point in the y direction, and then bend upward along the four fingers.

Page 15 498425 V. Description of the invention (12) Rotate the above image field inclination to adjust the image field where the crystal grains are located to a horizontal state. It is worth noting here that the judgment of the image field tilt is positive or negative: if the asymmetric layout pattern of the crystal grains is left-right asymmetry (that is, the layout pattern of the crystal grains is asymmetric in the X direction), and The left side is the high-density layout pattern area and the right is the low-density layout pattern area. The image field tilt is positive. Conversely, if the asymmetric layout pattern of the grains is left-right asymmetry, and the left is the low-density layout pattern area and the right For a high-density layout pattern area, the image field tilt is negative. Similarly, if the asymmetric layout pattern of the crystal grains is asymmetrical up and down (that is, the layout pattern of the crystal grains is asymmetric in the y direction), and the upper side is a high-density layout pattern area and the lower side is a low-density layout pattern area, the image is like The field tilt is positive. Conversely, if the asymmetric layout pattern of the crystal grains is asymmetrical up and down, and the upper side is a low density layout pattern area and the lower side is a high density layout pattern area, the image field tilt is negative. According to a preferred embodiment of the present invention, a method for measuring the horizontal inclination of an image field according to the present invention will be described with reference to FIG. 6. Please refer to FIG. 6. The present invention provides a method for measuring the horizontal inclination of an image field, wherein the crystal grains in the image field have at least two asymmetric integrated circuit layout patterns composed of pattern regions with different densities, and the two The pattern regions having different densities are a first pattern region and a second pattern region having a lower density than the first pattern region. The method includes at least the following steps:

Page 16 498425 V. Description of the invention (13) First, energy-focus is applied to all the crystal grains in this image field (step 602). Then, a scanning electron microscope (SEM) image of the first pattern region or the second pattern region in the image field is captured (step 604). Then analyze the profile of the scanning electron microscope image to find the first pattern interval or the first pattern interval of the first sampled grain and the second sampled grain of the image field along the direction of the asymmetric layout pattern of the grains. Focus gap between two patterns, in which all the first pattern regions and the second pattern regions in this direction are aligned in a line, and the focus gap refers to the first pattern region (or the second pattern region) of the first sampling die. Minus the difference between the in-focus degree of the first pattern area (or the second pattern area) of the second sampling die (step 606). Then, the distance between the two first pattern sections or the two second pattern sections is measured (step 608). Then calculate the ratio of this focus gap to this distance, where this ratio is the horizontal tilt of the image field (step 6 1 0). Then find out the horizontal tilt direction of the image field, where the horizontal tilt direction of the image field can be found using the right-hand spiral rule, and the right-hand spiral rule is to point the palm of a right palm with the thumb and the four fingers straight. It is vertical, and the directions of the four straight fingers are the same as the directions of the first sampling grain toward the second sampling grain, and the palm of the right palm points to the bottom of the grain. The value of the horizontal tilt of the field is positive or negative. If the value of the horizontal tilt of the image field is positive, the direction of the horizontal tilt of the image field is straightened with four fingers pointing toward the back of the right palm. Direction, and if the value of the horizontal inclination of the image field is negative, the direction of the horizontal inclination of the image field is straightened for this and four fingers point to the right

Page 17 498425 V. Description of the invention (14) The palm of the palm points in the direction of bending (step 6 1 2). Now, according to another preferred embodiment of the present invention, a method for measuring the horizontal inclination of an image field according to the present invention will be described with reference to FIG. Please refer to FIG. 7. The present invention proposes another method for measuring the horizontal inclination of an image field, in which the crystal grains in the image field have at least two asymmetric integrated circuit layout patterns composed of pattern areas with different densities, and these two The pattern areas with different densities are a first pattern area and a second pattern area having a lower density than the first pattern area. The method includes at least the following steps: measuring the height of the first pattern area in the image field Subtract the height difference of the height of the second pattern area (step 702). Then measure the length of this image field along the direction of the asymmetric layout pattern of the crystal grains, in which all the first pattern areas and the second pattern areas in this direction are arranged in a straight line (step 704). The user then uses the results of a fixed image field size of different grain numbers to find the correction parameters used to correct the horizontal tilt of the image field, where the value of the correction parameter includes 0 and 1 and is between 0 and 1. In addition, the value of this correction parameter is inversely proportional to the number of grains that this image field has in this direction (step 706). Then calculate the ratio of this height difference to the length (step 7 0 8 and then calculate the product of this ratio and the correction parameter, where this product is the horizontal tilt of the image field (step 7 1 0). Then find this Horizontal tilt direction of the image field, where the horizontal tilt direction of the image field can be determined by the right-handed spiral

P.18 498425 V. Explanation of the invention (15), and the right-hand spiral rule is that the palm of a right palm is perpendicular to the thumb and the four fingers, and the four fingers The direction is the same as that of the first pattern area toward the second pattern area, and the palm of the right palm points to the bottom of the die. As for the horizontal tilt direction of the image field, the value of the horizontal tilt of the image field is positive or negative. If the value of the horizontal inclination of the image field is positive, the direction of the horizontal inclination of the image field is straightened with four fingers pointing in a curved direction toward the back of the right palm, and if the value of the horizontal inclination of the image field is negative , Then the horizontal tilt direction of the image field is straightened with four fingers pointing towards the direction of the palm of the right palm (step 71 2). If the number of grains in the image field in this direction is 1, 2, 3, 4, 5, respectively, the values of the correction parameters are about 0.96 to 1 (preferably about 1). , 0 · 6 4 ~ 0 · 6 8 (preferred value is about 0 · 6 6), 0 · 32 ~ 0.36 (preferred value is about 0 · 34), 0 · 14 ~ 0 · 18 (preferred value is about 16), 0. 04 to 0. 08 (preferably about 0. 06). The above are merely preferred embodiments of the present invention, and are not intended to limit the scope of patent application for the present invention; any equivalent changes or modifications made without departing from the spirit disclosed by the present invention shall be considered as The protection scope of the present invention. The scope of patent protection of the present invention depends on the scope of patent application and its equivalent fields. /

Page 498 425425 Brief description of the diagram. Figure 1 is a schematic diagram of an image field with 2 X 3 layout patterns of asymmetric crystal grains in the X direction. Figure 2 is a preferred embodiment of the present invention. Relation diagram of the grain distribution of the image field in the direction of the asymmetric pattern; Figure 3 is a schematic diagram of an example of calculating the tilt of the image field according to a preferred embodiment of the present invention; Figure 4 is a preferred embodiment according to the present invention. Figures 5A to 5B are schematic diagrams of how to determine the adjustment direction of the image field level according to the image field tilt according to a preferred embodiment of the present invention; Six is a flowchart of a method for measuring horizontal inclination of an image field according to a preferred embodiment of the present invention; FIG. 7 is a flowchart of a method for measuring horizontal inclination of an image field according to another preferred embodiment of the present invention . Drawing number part: image field 100; first grain 101; first high-density layout pattern area 101a; first low-density layout pattern area 1010b; second grain 1002; Two high-density layout pattern areas 102a; second low-density layout pattern areas 102b;

Page 498425 The diagram briefly illustrates the third die 103; the third high-density layout pattern area; the third low-density layout pattern area; the fourth die 104; the fourth high-density layout pattern area; the fourth low-density layout. Pattern area fifth grain 105; fifth high density layout pattern area fifth low density layout pattern area sixth grain 106; sixth high density layout pattern area sixth low density layout pattern area coated with light The first horizontal sensing area 200 a; the second horizontal sensing area 200 b; the third horizontal sensing area 200 c; the fourth horizontal sensing area 2000 d. 10 3a; 103b; 104a; 104b; 105a; 105b; 10 6a; 106b;

Claims (1)

498425 VI. Application for patent scope 1. A method for measuring the horizontal tilt of an image field, wherein the crystal grains in the image field have at least two asymmetric integrated circuit layout patterns composed of pattern areas with different densities, and the two The pattern regions with different densities are a first pattern region and a second pattern region having a lower density than the first pattern region, wherein the method includes at least the following steps: applying energy focus (focus) to the image field Scanning electron microscope (SEM) images of the first pattern region or the second pattern region in the image field are taken on all of the crystal grains in the image field; the outline of the scanning electron microscope image is analyzed to obtain the The focus difference between the first pattern interval or the second pattern interval of an image field along the direction of the asymmetric layout pattern of the crystal grains, and all of the directions in the direction The first pattern area and the second pattern area are arranged in a straight line, and the focus gap refers to the degree of focus of the first pattern area (or the second pattern area) of the first sampling die minus The difference between the intensities of the first pattern area (or the second pattern area) of the second sampled crystal grains; the distance between the two first pattern intervals or the two second pattern intervals is measured and calculated Find the ratio of the focus gap to the distance, where the ratio is the horizontal tilt of the image field; find the horizontal tilt direction of the image field, where the horizontal tilt direction of the image field can be found using the right-hand spiral rule, the right-hand spiral rule The palm of one right palm is perpendicular to the thumb and four fingers straight, Page 22 498425 6. The scope of the patent application and the four fingers pointing in the same direction as the direction of the first sampling die toward the second sampling die, and the palm of the right palm points to the bottom of the die, As for the horizontal tilt of the image field, the value of the horizontal tilt of the image field is positive or negative. If the value of the horizontal tilt of the image field is positive, then the horizontal tilt of the image field is the straight four fingers toward the The back of the palm of the right palm points in a curved direction, and if the value of the horizontal inclination of the image field is negative, the image field is horizontal. The oblique direction is that the straight four fingers point in a curved direction toward the palm of the right palm. 2. —A method for measuring the horizontal tilt of an image field, wherein the crystal grains in the image field have an asymmetric integrated circuit layout pattern composed of at least two pattern areas with different densities, and the two pattern areas with different densities Are the first pattern region and the second pattern region having a lower density than the first pattern region, wherein the method includes at least the following steps: measuring the height of the first pattern region in the image field minus the second pattern region The south degree difference of the pattern area is measured, and the length of the image field along the direction of the asymmetric layout pattern of the crystal grains is measured, wherein all the first pattern area and the second pattern area in the direction are arranged. Find a correction parameter to correct the horizontal tilt of the image field, where the value of the correction parameter contains 0 and 1 and is between 0 and 1, and the value of the correction parameter and the image field are in the direction The number of grains on the surface is inversely proportional, and the relationship between the value of the correction parameter and the number of grains in the direction of the image field can be fixed by using the size of the image field in the direction of the image field. The crystal The number of grains is obtained by analyzing the horizontal tilt of the image field. Page 23 498425 VI. Calculate the ratio of the height difference to the length of the patent application; calculate the product of the ratio and the correction parameter, where the product is the horizontal tilt of the image field; find the horizontal tilt of the image field Direction, where the horizontal tilt direction of the image field can be found using the right-hand spiral rule, which points the palm of a right palm perpendicular to the thumb and the four fingers straight, and the four fingers The direction is the same as that of the first pattern area toward the second pattern area, and the palm of the right palm points to the bottom of the crystal grain. As for the horizontal tilt direction of the image field and the horizontal tilt value of the image field, the values are positive. Or if it is negative, if the value of the horizontal tilt of the image field is positive, the direction of the horizontal tilt of the image field is the direction in which the four straight fingers point toward the back of the palm of the right palm, and if the horizontal tilt of the image field is If the value is negative, the horizontal tilt direction of the image field is the direction in which the four straight fingers point toward the palm of the right palm and bend. 3. If the method of applying for the second item of the patent scope, wherein the number of the crystal grains in the image field in the direction is 1, then the value of the correction parameter is about 0 · 9 6 ~ 1 〇4. The method of item No. 2 of the patent, wherein if the number of the crystal grains in the image field in the direction is 2, the value of the correction parameter is about 0. 6 4 to 0. 68. 5. If the method of claim 2 is applied, if the number of grains in the image field in the direction is 3, the value of the correction parameter is about Page 24 498425 VI. The scope of application for patents is from 0.32 to 0.36. 6. The method according to item 2 of the patent application range, wherein if the number of the crystal grains in the image field in the direction is 4, the value of the correction parameter is about 0 · 14 ~ 0 · 18. 7. If the method of claim 2 is applied, if the number of the crystal grains in the image field in the direction is 5, the value of the correction parameter is about 0 · 04 ~ 0 · 08. 8. —A method for measuring the horizontal tilt of an image field, wherein the crystal grains in the image field have an asymmetric integrated circuit layout pattern composed of at least two pattern areas with different densities, and the two pattern areas with different densities Are the first pattern region and the second pattern region having a lower density than the first pattern region, wherein the method includes at least the following steps: measuring the height of the first pattern region in the image field minus the second pattern region The height difference of the pattern area; the length of the image field along the direction of the asymmetric layout pattern of the die is measured, wherein all the first pattern area and the second pattern area in the direction are aligned in a line Find a correction parameter to correct the horizontal tilt of the image field, where the value of the correction parameter contains 0 and 1 and is between 0 and 1, and the value of the correction parameter and the image field in the direction The number of the crystal grains is inversely proportional, and the value of the correction parameter is the number of the crystal grains that the image field has in the direction. Page 25 498425 6. The relationship between the scope of the patent application can be obtained by fixing the image field size and analyzing the horizontal tilt of the image field by the number of different crystal grains in the direction of the image field, where the image If the number of grains in the field in the direction is 1, 2, 3, 4, and 5, respectively, the value of the correction parameter is about 0.96 to 1, 0.64 to 0.68, 0.32 to 0.36, and 0.14. ~ 0.18, 0.04 ~ 0.08; calculate the ratio of the height difference to the length; calculate the product of the ratio and the correction parameter, where the product is the horizontal tilt of the image field; find the horizontal tilt direction of the image field, The horizontal tilt direction of the image field can be found by using the right-hand spiral rule. The right-hand spiral rule is that the palm of a right palm is perpendicular to the direction of the thumb and the four fingers of the straight four fingers. The direction of the first pattern area toward the second pattern area is the same, and the palm of the right palm points to the bottom of the grain. As for the value of the horizontal tilt of the image field and the horizontal tilt of the image field, the value is positive or Negative correlation If the value of the horizontal tilt of the image field is positive, the direction of the horizontal tilt of the image field is the direction in which the four straight fingers point toward the palm of the right palm and bend, and if the value of the horizontal tilt of the image field is negative , The horizontal tilt direction of the image field is a direction in which the four straight fingers point toward the palm of the right palm and bend. 9. The method according to item 8 of the scope of patent application, wherein if the number of the crystal grains in the image field in the direction is 1, the value of the correction parameter is about 1. 10. The method according to item 8 of the scope of patent application, wherein if the number of the crystal grains in the image field in the direction is 2, the value of the correction parameter is approximately Page 26 498425 6. The scope of patent application is 0.66. 1 1. The method according to item 8 of the scope of patent application, wherein if the number of the crystal grains in the image field in the direction is 3, the value of the correction parameter is about 0.34. 1 2. The method according to item 8 of the scope of patent application, wherein if the number of grains in the image field in the direction is 4, the value of the correction parameter is approximately 0.16 ^ 1 3. The method of 8 items, wherein if the number of the grains in the image field in the direction is 5, the value of the correction parameter is about 0.06 α Page 27