TW559986B - Method of fabricating shallow trench isolation - Google Patents

Abstract

A method of fabricating a shallow trench isolation. A pad oxide layer, a mask layer, a dielectric anti-reflection coating layer and a cap oxide layer are formed on a substrate sequentially. A trench is formed in the substrate. A liner oxide layer is formed along a surface of the trench. An isolation layer is formed over the substrate to fill the trench. Using the mask layer as a polishing endpoint, the insulation layer, the dielectric anti-reflection coating layer and the cap oxide layer over the mask layer are removed. The thickness of the mask layer is controller within a first fixed range, and the thickness of the dielectric anti-reflection coating layer is controller within a second fixed range, such that the light source of the optical endpoint detection system can produce a maximum reflected light signal. The mask layer and the pad oxide layer are then removed.

Description

559986 V. Description of the invention (1) The present invention relates to a method for manufacturing a component isolation structure, and in particular to a method for manufacturing a shallow trench isolation structure (S ha 1 1 0w Trench Isolation 'for short, $ TI). In order to improve the stability of the end point detection (E nd-point Detecting) of the shallow trench isolation structure. In today's booming development of integrated circuits, component downsizing and integration are an inevitable trend and an important issue for the active development of all sectors. When the component size is gradually reduced, the integration level is gradually increased, and the isolation structure between components must be reduced, so the difficulty of component isolation technology is gradually increasing. In the past, device isolation used field oxide (LOCOS) to form a field oxide layer (Fieid Oxide). The field oxide layer is limited by its bird (beak) characteristics. It has always been difficult to reduce its size. In view of this, other component isolation methods have been continuously developed. Among them, Shallow Trench Isolation (STI) is most widely used, especially in Sub-half Micron integrated circuit manufacturing processes. . A conventional method for manufacturing a shallow trench isolation structure is to form a pad oxide layer and a silicon nitride mask layer on a substrate, and then use an anisotropic (Ani sotropi c) dry etching method to etch out the substrate. Steep ditch. Then, the trench is filled with an insulating layer and a chemical mechanical polishing process is used to remove the insulating layer outside the trench as a component isolation structure. Finally, the silicon nitride mask layer and pad oxide layer are removed. However, the conventional method does not mention any method about the stable end point detection during the CMP process. Because while the component size is getting smaller and smaller and the accumulation is developing,

7382twf.ptd Page 5 559986 V. Description of the invention (2) The silicon nitride mask layer used as the polishing end point will become thinner and thinner, so it will affect the stability of the end point detection and reduce the reliability of the end point detection. Therefore, how to achieve the stability of the end-point debt measurement is an issue that cannot be ignored. The invention provides a method for manufacturing a shallow trench isolation structure with the stability of point detection. The method includes sequentially forming a pad oxide layer, a mask layer, and a dielectric anti-reflection coating layer on a substrate. Dielectric Anti-Reflection Coating, abbreviated as DAR (W), and then a patterner = :: layer is formed on the top cover oxide layer, and the patterned photoresist layer is used as a mask to illuminate the top cover oxide layer. The coating layer, the mask layer, and the pad oxide layer are rubbed, and continue for a while.] A trench is formed in the substrate. Then, the patterned photoresist layer is removed, and an oxide layer is formed on the surface of the trench and formed on the substrate. An insulating layer is filled with =. Subsequently, the mask layer is used as the polishing end point, and a part of the insulating layer and the dielectric anti-reflection coating layer on the mask layer are removed by chemical mechanical polishing, and the chemical mechanical polishing process The middle system uses an optical endpoint ^^ system for endpoint detection. The thickness of the mask layer is controlled at a first fixed target, and the thickness of the dielectric anti-reflection coating layer is controlled at a second fixed target. Used by optical endpoint detection systems The light source can generate a large reflected light signal. Then the mask layer and the pad oxide layer are removed. In order to achieve the effect of stable endpoint detection, the present invention is matched with the mask sound and the anti-reflection layer, that is, the mask layer The structure with the anti-reflective layer # is in a fixed thickness range to improve the base reflectance at the end point detection, because the greater the base, the greater the reflectance, the more reliable the end point detection (Reliabiη), and then reach shallow trenches Endpoint detection of isolated structures

559986 V. Description of Invention (3) ''

Detecting). ▲ In order to make the above and other objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is given below and described in detail with the accompanying drawings as follows: '' Brief description of the mark: 1 0 0 · Substrate 102: pad oxide layer 104, 104a: mask layer 106; dielectric anti-reflection coating layer I 08: oxide layer II2: photoresist layer 11 4: trench 11 6: Almost oxide layers 11 8 and 11 8 a: Insulating layer 12 0: Shallow trench isolation structure embodiment FIGS. 1A to 1E are schematic cross-sectional views illustrating a manufacturing process of a shallow trench isolation structure according to a preferred embodiment of the present invention. Referring to FIG. 1A, a pad oxide layer 102, a curtain layer 104, and a dielectric anti-reflection coating (Die1ectric Anti-Ref1ection Coating) are sequentially formed on the Shixi substrate 100. (DRC for short) 106 and a cap oxide layer (Cap Oxide) 108, and then a patterned photoresist layer is formed on the cap oxide layer (Cap Oxide) 108. Among them, the rhenium oxide layer 102 is used to protect the substrate 100 from subsequent processes.

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V. Description of the invention (4) Damaged, its formation method such as thermal oxidation method; and the cover layer method such as chemical vapor deposition method, the material of which is, for example, 20% anti-reflection coating layer of silicon nitride can be reduced. Error caused by photoresist exposure; # 化 层 108 is used as a reinforcement layer of the dielectric anti-reflection coating layer 106, and has the function of anti-reflection. ^ 〃 In order to achieve the effect of stabilizing the end point detection of the shallow trench isolation structure (hd point detecting), it is necessary to improve the base reflectivity. Therefore, the structure of the mask layer 104 and the dielectric anti-reflection coating layer 106 is used. For example, the thickness of the mask layer 104 or the thickness of the mask layer 04 and the dielectric anti-reflection coating layer 06 is within a fixed range; for example, if the optical end point detection system (Optical End Point When the detection light wavelength used by the Detection System is 637 nanometers, the thickness of the cover layer i04 needs to be between 120 and 1800 angstroms' and the preferred range is 1 2 0 0 to 1 600 angstroms. The thickness of the dielectric anti-reflection coating layer 106 is, for example, between 450 and 105 angstroms. Therefore, the reliability of the end point detection (Re 丨 i ab i 丨 i t y) can be improved according to the above structure, so that the light source used by the optical end point detection system can generate the maximum reflected light signal. Next, referring to FIG. 1B, the photoresist layer 112 is used as a mask to cover the top oxide layer 108, the dielectric anti-reflection coating layer 106, the mask layer 104, and the pad oxide layer 102. Etching is performed, and etching is continued to the substrate 100 to form a trench 114. The etching method uses, for example, an anisotropic money engraving process. This photoresist layer 11 2 is then removed. Please refer to FIG. 1C to form a linear oxide layer 116 on the surface of the trench 114. A layer of insulation is then formed on the substrate 100

7382twf.ptd Page 8 559986 V. Description of the invention (5) The edge layer 11 8 fills the trench i 丨 4. The material of the insulating layer 丨 丨 8 is, for example, silicon oxide. Its formation method is, for example, high-density plasma chemical gas. Phase deposition method (Hidden Density Plasma CVD) 〇 Then 'Please refer to Figure 1D, using the mask layer 丨 04 as the end point of the polishing, using chemical mechanical polishing to remove the insulating layer on the mask layer 丨 04 8. The dielectric anti-reflection coating layer 106 and the oxide layer 108 are used for the end point detection in the chemical mechanical polishing process using the = optical end point detection system. Because the thickness of the mask layer 丨 and the dielectric anti-reflection coating layer 106 is controlled within a fixed range, the light source used by the optical endpoint detection system can produce the maximum The reflected light signal therefore improves the reflectivity of the substrate 100 to achieve the effect of stable end point detection of the shallow trench isolation structure: so the reliability of the end point detection can be improved. After the chemical process, the insulating layer 118a only exists in the trench 114, and the mask layer 104, which is the final polishing layer, will also become a thinner mask layer 10 ". Finally, please refer to Figure 1E, remove the mask For the curtain layer 104a, when the material of the cover 104a is, for example, silicon nitride, a thermal phosphoric acid solution is used. Then, the method of shifting the potential mtfi04a is, for example, ^^ M.4120, ^ / Λ ^^^^^ Xuan Chen Wanfa is etched with hydrofluoric acid (HF), for example. In order to verify that the method of the present invention can indeed improve the anti-material, please refer to the diagram shown in Figure 2A to simulate Figures ία to sergeants, sergeants ..., .A ^. ^ ^ ® In the method shown in Figure 1b, the base material is used for end point detection; as shown in the figure below, the structure of the conventional military curtain layer anti-anti 2 cloth layer is simulated to perform the base case when the end point is detected. The thickness of 104 is between 1 200 and 1 800 angstroms.

559986 V. Description of the invention (6) When the thickness of the dielectric anti-reflection coating layer is between 0 and 50 angstroms, the relationship between the 100 reflectance of the substrate and the detected thickness is as follows: As shown in Figure 2A, the amplitude of its reflectivity (Ampli. Heart 0 · 25. Sentences, then please refer to Figure 2B. According to the conventional structure of the mask layer and the dielectric anti-reflection coating layer, the endpoint detection is performed. The relationship between the obtained substrate reflectance and the detection thickness is shown in FIG. 2B, and the amplitude of the reflectance is about "", 0.175. Therefore, it can be clearly seen that the present invention is more suitable for endpoint detection than the conventional method. A higher amplitude of the substrate reflectance can be obtained. Therefore, the present invention is characterized by matching the structure of the mask layer and the anti-reflection layer to improve the substrate reflectance, thereby achieving the end point detection of the shallow trench isolation structure. Point Detecting), so it can improve the reliability of endpoint detection (Reiiability). Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Without departing from the invention Within the scope of arsenic and seeds, it is intended that the modifications and variations of the present invention and therefore the scope of protection when view = the defined scope of the appended patent application, whichever of. '

Ptd Page 10 559986 Brief description of the drawings Figures 1A to 1E are schematic cross-sectional views of the manufacturing process of a shallow trench isolation structure according to a preferred embodiment of the present invention; Figure 2A is a simulation of Figure 1A The substrate reflectance when endpoint detection is performed in the method to FIG. 1E; and the structure shown in FIG. 2B is a simulation of the structure of a conventional mask layer and a dielectric anti-reflection coating layer to perform substrate reflection during endpoint detection. rate.

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Claims (1)

559986 Application Patent Scope 1 · A method for manufacturing a shallow trench isolation structure, the steps include: providing a substrate; forming an oxide layer on the substrate; forming a mask layer on the pad oxide layer; and forming the mask layer on the mask layer A dielectric anti-reflection coating layer is formed thereon; a capping oxide layer is formed on the dielectric anti-reflection coating layer; a patterned photoresist layer is formed on the capping oxide layer; The patterned photoresist layer is a mask, and the top oxide layer anti-reflection coating layer, the mask layer and the pad oxide layer are etched and etched into the substrate to form a trench; removing the patterned photoresist layer Forming an lining oxide layer on the surface of the trench; forming an insulating layer on the delta substrate and filling the trench; using the mask layer as the end point of polishing, using a chemical mechanical polishing process to remove a portion on the mask layer The insulating layer, the dielectric anti-reflection coating layer and the top oxide layer, wherein the chemical mechanical polishing process uses an end point detection system for end point detection; removing the cover layer; and removing The塾 oxide layer, wherein the thickness of the '5 mysterious mask layer is controlled in a first fixed range, and the thickness of the dielectric anti-reflection coating layer is controlled in a second fixed range, so that the optical endpoint detection system Using one of the light sources can produce the signal with the largest reflected light. 〃 2. Manufacture of shallow trench isolation structure as described in item 1 of the scope of patent application 7382twf.ptd 559986 6. Scope of Patent Application Method, wherein the material of the cover layer includes silicon nitride. 3. The trench isolation method described in item 2 of the scope of patent application, wherein the optical endpoint detection system uses a 637 nm nanometer structure. The wavelength of the light source used is Xi. Research on the 3rd issue of the prison perimeter < Shallow trench isolation method of surname, where the mask layer of the / fixed range of ^ / 1 20 0 ~ 1 80 0 Between Egypt. Good X. The method of the shallow trench isolation structure as described in item 3 of the scope of the patent application, wherein the thickness of the first fixed range of the cover layer is between 1200 and 1600 Angstroms. & 6. The method for manufacturing a shallow trench isolation structure as described in item 3 of the scope of the patent application, wherein the second fixed range of the dielectric anti-reflection coating layer is between 4 50 and 1 0 50 . 7. The method for manufacturing a shallow trench isolation structure as described in item 1 of the scope of patent application, wherein the method for forming the insulating layer includes a high-density plasma chemical vapor deposition method. 8. The manufacturing method of the shallow trench isolation structure described in item 1 of the scope of the patent application, wherein the method of removing the mask layer is using a hot phosphoric acid solution. 9. The manufacturing method of the shallow trench isolation structure described in item 1 of the scope of the patent application, wherein the method of removing the pad oxide layer is etching with hydrofluoric acid. 10. A method for manufacturing a shallow trench isolation structure, the steps include: providing a substrate; forming a pad oxide layer on the substrate; forming a mask layer on the pad layer; 7382twf.ptd Page 13 559986 6. The scope of the patent application is the mask layer, the dielectric reactance and the top cover oxygen, and the patterned anti-reflective coating layer, which is engraved into the substrate to remove the pattern in the trench. The cover oxide layer is used to remove the top oxide layer on the substrate on the substrate, and the end point debt measurement system removes the single screen to remove the pad oxygen. The cover optical end point detection system is a light signal. 11 · The method as claimed in the patent, wherein the cover 1 2 · The method as claimed in the patent, wherein the light is 6 3 7 nm. 1 3. If a reflective coating layer is formed on the application patent to form the overlying photoresist layer as the cover layer to form the surface of the photoresist layer and form a part to be polished as the final detection layer; and The thickness of the curtain layer, the range of thickness used by the curtain layer, the material range of the curtain layer, the 11th end point of the dielectric anti-reflection coating layer; a cover oxide layer is formed on the layer to form a patterned photoresist layer; The top oxide layer and the pad oxide layer are etched to form a trench; the dielectric layer continues to line the oxide layer; the edge layer fills the trench; the end point is a chemical mechanical polishing process, the insulating layer, and the dielectric anti-reflection In the coating layer and the chemical mechanical polishing process, a photometric measurement is used; the degree is controlled in a fixed range, so that one of the light sources can produce the manufacturing structure of the shallow trench isolation structure with the largest inverse term, including silicon nitride. Manufacture of the shallow trench isolation structure described in item 1, the wavelength of the light source used in the measurement system is in the range of the shallow trench isolation structure described in item 12 7382twf.ptd Page 14 559986 VI. Patent Application Method, wherein the thickness of the fixed range of the cover layer is between 1200 and 1800 Angstroms. 1 4 · The method for manufacturing a shallow trench isolation structure as described in item 12 of the scope of patent application, wherein the thickness of the fixed range of the cover layer is between 1200 and 1600 Angstroms. 1 5 · The method for manufacturing a shallow trench isolation structure as described in item 12 of the scope of patent application, wherein the thickness of the dielectric anti-reflection coating layer is between 450 and 1 050 Angstroms. The manufacturing method of the shallow trench isolation structure described in item 0, wherein the method of forming the insulating layer includes a high-density plasma chemical deposition method. 17. The method for manufacturing a shallow trench isolation structure as described in item 10 of the scope of the patent application, wherein the method of removing the mask layer uses a hot phosphoric acid solution. σ ^ Manufacture of shallow trench isolation structure as described in item 10 of the patent scope // The method of removing the pad oxide layer is etching with hydrofluoric acid. 7382twf.ptd Page 15