TW391041B - Alignment mark structure with dummy pattern - Google Patents

Abstract

An alignment mark structure with dummy pattern is designed on the surface of a wafer. A dummy pattern is designed on the periphery of each alignment mark. The density of dummy pattern is designed based on the density of the elements. With the alignment mark structure with dummy pattern in accordance with the present invention, the alignment mark is prevented from being over polished in the chemical mechanical polishing process, which may cause an erroneous alignment and a distortion in transferring patterns.

Description

2936twf.doc / 008 2936twf.doc / 008 Printed by Shellfish Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs_ ^-V. Description of the Invention (i) The present invention relates to a structure of an alignment mark, and is particularly It is related to the use of a dummy pattern around the alignment mark to reduce the damage caused by the alignment mark in the chemical mechanics honing method (Chemical Mechanicai Polishing; CMP). Integrated circuits (ICs) are almost ubiquitous in our daily lives. However, the process of "integrated circuit production is very complicated" basically "it takes about hundreds of different steps and takes about one or two months to complete. The integrated circuit industry is basically a high-tech industry composed of four major branches: 1C design, wafer manufacturing, wafer testing, and wafer packaging. Therefore, the integrated circuit industry is not only an advanced technology industry ', but also a high-risk industry that requires huge capital to maintain its continued development. In wafer manufacturing, there are multiple processes including oxidation, diffusion, deposition, patterning, and engraving. In terms of the formation of the wafer pattern alone, the tool required for the exposure of the surface of the wafer to the photoresist is in addition to a light source. The most important thing is a photomask for forming a specific pattern of the thin film layer. Taking the general process of making components as an example, 'the number of photomasks required for a product is usually about 10 to 18 depending on its complexity'. Therefore, in the fabrication of semiconductors, the alignment between the layers must be done before each exposure of the photoresist is performed. Otherwise, improper pattern transfer will cause the entire wafer to be scrapped. In addition, with the advancement of technology, 'in the case of shrinking semiconductor components,' the deep sub-Half 3 I paper with a line width of 0.18 μm has been adopted (Deep Sub-Half 3 I paper size applies to Chinese National Standard (CNS) A4 specifications (2⑴X297 Gongchu) " " ^ (Please read the precautions before filling in this page), 1T 2936twf.doc / 008 Λ7 B7 Printed by the Shellfish Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs 5. Description of the invention ())

In the case of Micron), the use of a chemical mechanical honing (CMP) method as a planarization process has become increasingly important. However, when CMP honing semiconductor devices, the alignment marks will also be flattened. This will make it difficult to align the photomasks and cause serious alignment error problems. The relative patterns may also be incorrectly transferred. Next, please refer to FIG. 1 to show an alignment mark on the wafer. The figure includes a wafer 100 and two alignment marks 102. Two of the alignment marks 102 are generally designed in non-element areas (not shown in the figure), such as specific reserved areas or dicing between wafers. Road. The two alignment marks 102 are used for mask alignment during pattern transfer. In the figure, the two alignment marks 102 are greatly enlarged on the wafer. Actually, on the product, the two alignment marks 102 are very small. Next, please refer to Fig. 2 for an enlarged view of the alignment mark of Fig. 1. Among them, the alignment mark 102 is composed of a plurality of grooves 104 (where the figure is a top view and is represented by a black line) in a staggered manner. When the lithography process is performing alignment, the alignment mark is illuminated by a light source and is affected by a plurality of grooves 104. After reflection, a wave path difference is generated for alignment. Next, please refer to FIGS. 3a to 3f, and show a cross-sectional flowchart of the formation of the alignment mark area affected by the CMP. Among them, in FIG. 1 and FIG. 2, the alignment mark structure viewed from above is viewed, and 3a to 3f are alignment marks viewed from a cross section 7] First, as shown in FIG. 3a, The alignment mark 10 is composed of a plurality of grooves, such as the two grooves 102a and 102b in the figure, to form the features of the alignment mark, and when using the reflected light waves in the alignment mark 102, 4 (please first (Read the notes on the back and fill out this page)

、 1T This paper size applies to Chinese National Standard (CNS) Λ4 specification (210 × 297 cm) 2936twf. Doc / 008 2936twf. Doc / 008 Printed by the Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs

IM 5. Description of the invention U) Wavelength difference formed by U) to complete the alignment. Next, referring to FIG. 3b ', semiconductor elements such as a silicon base layer, a source / drain region, a gate electrode, a field oxide layer, etc. are successively formed on the wafer 100. Since how to form a semiconductor element is not the focus of the present invention, it is not shown in the figure, but only the formed element layer is shown on the alignment mark 102, collectively referred to as the semiconductor element layer 106. The semiconductor element layer 106 will be formed in a concave-convex shape with the contours 'of the grooves 102a, 102b, so the features of the alignment mark 102' will still be maintained, which will not cause the problem of alignment mark failure. Next, referring to FIG. 3c, a mask (not shown) is used to define the pattern, and the unprotected part of the semiconductor element layer 106 is removed, leaving only the semiconductor element layer 106a. After that, a dielectric layer 108 is formed. The dielectric layer 108 is subjected to a planarization process by a CMP method. > Then, referring to FIG. 3d, a portion of the dielectric layer 108 'is removed by using a photomask, and only the dielectric layer 108a is left to expose the alignment mark 102, and the characteristics of the grooves ~ 102a and 102b are restored. Finally, referring to FIG. 3e, a conductive layer 110, such as a tungsten metal layer, is formed on the device. The conductive layer 丄 10 must be subjected to a CMP honing planarization process to form a plug. A disc-shaped recess (Dishing) will be formed during CMP honing, and honing to the deposited portions on the grooves 102a, 102b will cause the features of the alignment mark 102 to be inconspicuous' or even completely disappear. , So that the alignment effect is lost. Next, please refer to FIG. 4 'for a top view of a conventional alignment mark after CMP and honing. Due to the alignment mark 102 and the component area on the wafer (not 5 --- ^ --- ^ ------(Please read the precautions on the back before filling this page)

、 1T This paper size applies to Chinese National Standard (CNS) Α4 specification (210X297 cm) 2 9 3 6 twf. Doc / 〇 8 2 9 3 6 twf. Doc / 〇 〇 8 Off-line consumption by the China Standards Bureau of the Ministry of Economic Affairs Printed by the cooperative. 5. Description of the invention (shown)), there is often a long blank space Π2 '. Therefore, when CMP honing, it is easy to produce a hollow phenomenon in this blank area'. The density of the component area is also far away. The density is much larger than that of the alignment mark. When honing the component area, it requires larger honing because of the high density, but it is impossible to use two different honing methods for the low density alignment mark. Considering whether the alignment mark is excessively honing, a fuzzy alignment mark as shown in the figure will be generated. The precise alignment procedure cannot be achieved during the lithography process, and subsequent pattern transfers will cause pattern distortion. In the pattern-registration capability of using the photomask many times, there may be a Rotation error, a Scaling error, or the like. Therefore, the purpose of the present invention is to provide a structure with an alignment mark of a barrier film, so as to form a barrier film around each of the alignment mark layers, and design the density of the barrier film according to the density of the component area to avoid the alignment mark. Due to the low density around the layer, when CMP honing, misalignment caused by excessive honing causes the transfer pattern distortion to disappear. In addition, another object of the present invention is to provide a structure with an alignment mark for a barrier film, to protect the alignment mark with a barrier film, to further improve the leveling control ability, so that the step alignment sensor ( Stepper aiignment sensor) 'Due to the large gap between the alignment mark and the surrounding area, there will be no level problems during detection. According to the purpose of the present invention, a structure with an alignment mark of a barrier film is provided on a wafer surface, wherein the wafer has a plurality of wafers and a plurality of dicing tracks. The structure with the alignment mark of the barrier film includes ： * A plurality of alignment marks are located on the cutting path; and a plurality of barrier films, 6 --------— -_ (Please read the precautions on the ^ side before filling in this page)

、 1T This paper size is applicable to the Zhongguanjia Standard (CNS) M specification (2_297) 2936twf.doc / 008 5. Description of the invention (dagger) Each film is corresponding to the periphery of each alignment mark. To prevent chemical mechanical honing from damaging the standard mark. In order to make the above-mentioned objects, features, and advantages of the present invention more obvious and easy to understand, the following provides a preferred embodiment, which is described in detail with the accompanying drawings as follows: Brief description of the drawings: Figure 1 shows an alignment mark on the wafer; Figure 2 shows an enlarged image of the alignment mark of Figure 1; Figures 3a to 3f show the formation of the alignment mark area Sectional flow chart of CMP influence-Figure 4 shows the top view of a conventional alignment mark after CMP honing; Figure 5 shows a structure with an alignment mark of a barrier film according to the present invention; etc. Figure 6, Partial enlarged diagrams of the barrier film of Figure 5 are shown; and Figures 7a and 7b illustrate the errors in the XY axis coincidence of the structure using the alignment mark ^ of the barrier film of the present invention. Printed by the Shell Consumer Cooperative of the Central Sample Bureau of the Ministry of Economic Affairs (please first Read the notes on the back and fill in this page), π 100: Wafer 102: Alignment mark 102a, 102b, 104: Groove 106: Semiconductor element layer 108108a: Dielectric layer Π0: Conductive layer 112: Blank area 114 : Sealbook. I am anti-general China National Winter Cricket (CNS) Λ4 is present (21〇χ297 公 梦 2936twf.doc / 008 2936twf.doc / 008 Central Standards Bureau of the Ministry of Economic Affairs, Shellfish Consumer Cooperative Seal B7 5. Description of the invention (6) 啻 Example Please refer to FIG. 5 to illustrate a structure with an alignment mark of a barrier film according to the present invention. The difference between FIG. 5 and FIG. 4 is that it is originally located in the crystal The alignment mark 102 on the round surface is closely connected to the surroundings. The blocking film 114 is designed to prevent the chemical mark from being damaged by the standard mark. The alignment mark 102 is generally designed to be used on the dicing path reserved for dicing wafers. In the reserved space, and the number is at least two, the alignment process can be performed by the alignment machine. In addition, the structure with the alignment mark of the barrier film of the present invention, each alignment mark 102 corresponds to a barrier film 114, The density distribution in the barrier film is uniform and is based on the density of the wafer in the device area. Therefore, when performing CMP honing, because it has the same density as the wafer, it can effectively prevent the alignment mark from being subjected to excessive honing, so that the photomask can be accurately aligned, and can be used for each layer of pattern transfer. Design position. Next, please refer to Figure 6 to show the enlarged 115 part of the barrier film in Figure 5. Among them, the barrier film pattern can be freely designed, in fact, it is a special pattern designed for CMP and a certain distribution (that is, the barrier Film size) in order to obtain an alignment mark with better results in the CMP honing process. Next, please refer to FIG. 7a and FIG. 7b to show the structure using the alignment mark of the barrier film of the present invention coincides on the XY axis Degree error. For the alignment mark that generally does not have a barrier film, under CMP honing, the Shallow Trench Isolation (STI) will be aligned to get the best state of overlap error (94nm on X, Y is 97 nm. In tungsten etchback (and W-CMP), we get the best state of coincidence error, ‘134nm on X and 143nm on Y. Under the same conditions, if you use this 8 (Please read the precautions on the back before filling this page)

, 1T This paper size applies the Chinese National Standard (CNS) A4 specification (210 '乂 297mm_) 2936twf. Doc / 008 Λ7 印 7 Printed by the Shell Specimen Consumer Cooperative of the Central Sample Bureau of the Ministry of Economic Affairs 5. Description of the invention (q) According to the invention, under the CMP honing, in the actual operation of the shallow trench isolation alignment, the overlap error of the best state will be reduced to 52nm on X and 64nm on Y. On tungsten etchback, the best state of coincidence error is obtained, which is 81nm on X and 74nm on Y, which effectively reduces the occurrence of coincidence errors. In Figs. 7a and 7b, the horizontal axis represents the number of wafers, and the vertical axis represents the degree of coincidence between X and Y. In the present invention, the structure with the alignment mark of the barrier film, for the coincidence of X and Y with the originally designed position The degree is quite close to avoid the occurrence of alignment errors, that is, to verify that the above-mentioned STI and W-CMP overlap errors are reduced. Due to the design of a uniform barrier film, the alignment mark can obtain better results, so that when alignment is performed, it is possible to avoid the error of the leveling detection 'the alignment mark is too large from the surroundings'. Therefore, the feature of the present invention is to form a barrier film layer in alignment with the screen layer of the hanging layer, so that the density of the barrier film layer is equivalent to the density of the external element area, and the pattern and distribution required for the CMP design are After CMP honing, 1 * · »· can still maintain the accuracy of the alignment mark. In addition, the sensor can be aligned step by step. When performing the F-check level adjustment, the alignment problem will not occur due to the large difference between the alignment mark and the surroundings. Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention to "any person skilled in the art" without departing from the spirit and scope of the present invention, and can make various modifications and retouches. The scope of protection of the invention shall be determined by the scope of the attached patent application. 9 (Please read the precautions on the back before filling this page),-= β D This paper size applies to Chinese national standards (CNS > A4 specifications (210X297 mm)

Claims (1)

Printed by the Ministry of Economic Affairs of the Bureau of Industry and Engineering Cooperatives «. 6. Doc / ο ο 8 A8 B〇C8 • -----Bar ____ Patent application scope k A structure with an alignment mark of a barrier film, located at "A wafer surface" wherein the wafer has a plurality of dummy wafers and a plurality of scribe lines, and the structure with the alignment marks of the barrier film includes: a plurality of alignment marks located on the scribe lines; and " " A plurality of barrier films, each of which is respectively corresponding to the periphery of each of the alignment indications, to prevent a chemical mechanical honing from damaging the standard marks. 2. If the scope of patent application is the first item There are two alignment bottles with a barrier film and an alignment mark, wherein the alignment marks and the molds are two. What is the alignment mark with a barrier film described in item 1 of the scope of patent application? Acoustic structure, wherein the density of the mold is uniform. 4. The structure with the alignment mark of the film as described in item 3 of the scope of patent application, wherein the density of the mold is designed according to the density of the wafers ., 具有 as described in item 1 of the patent application The structure of the alignment mark, wherein the pattern of the block is a specific pattern and a distribution designed for the chemical mechanical honing. 6. A structure with the alignment mark of the block film is located on a wafer surface 'Where the wafer has a plurality of wafers and a plurality of reserved spaces, the structure with the alignment marks of the capture film includes: < a plurality of alignment marks located on the reserved spaces; and a plurality of barrier films in the factory Each of the barrier films is respectively closely connected to the periphery of each pair of markings and markings to prevent a chemical machinery from damaging or damaging the standard markings. With the alignment mark of the barrier film-... ----..-- 1--K Pack ------ Order -------. ≫ (Please read the note on the back first $ Xiang Zai'e wrote this page) This paper uses China National Standard (CNS) A4 size (210 > < 297mm) 2936 2936 Printed by the Central Government Bureau of the Ministry of Economic Affairs, Shellfisher Consumer Cooperative — _S______ Structure, wherein the alignment marks and the blocking modes are two. '彡. As described in the patent application _ item 6 The alignment marks of the film ·, and the rods, wherein the density of the impact mold is uniform. 9. The structure with the alignment marks of the film as described in item 8 of the stomach, where the densities of the radon It is designed based on the density of these wafers. 10. The structure with the alignment mark of the barrier film as described in the patent application _ item 6, wherein the pattern of the barrier mold is a specific design for the chemical mechanical honing. Patterns and a distribution.-~ Ji quasi-labeled structure with oligoblock film, located on the surface of the wafer, where there are multiple wafers and multiple reserved spaces on the chip. The structure of the mark includes: a plurality of alignment marks located on the reserved spaces; and < a plurality of barrier films, each of which is corresponding to the periphery of each of the alignment marks, respectively. The die densities are uniform and are served by the density of the wafers to prevent 'a chemical mechanical honing damage to the standard marks. 12. The structure with the alignment marks and indicators of the barrier film as described in item 11 of the scope of the patent application, wherein the alignment indicators and the barrier modes are two. 13. The alignment mark with a barrier film as described in item 11 of the scope of the patent application, wherein the patterns of the masks are a specific pattern and a distribution designed for the CMP machine. (Please read the note $ on the back before filling out this page). Binding and binding The paper size is in Chinese National Rolling Rate (CNS) A4 (210X297 mm)