TW461027B - Nitride-free manufacturing method of shallow trench isolation - Google Patents

Abstract

A one-step plasma etching process for STI formation capable of improving the trench profile is provided. This method has advantages of simple process and enhanced device performance. It comprises the following steps: defining a photo pattern on a semiconductor substrate; forming an organic polymer on the wafer surface in an etching chamber and anisotropically etching a trench in the same chamber; then depositing a trench filler and flattening the same; and finally forming a sacrificial oxide layer and using a wet-dip method to remove the sacrificial layer.

Description

4 6 1 0 2 7 V. Description of the invention (1) 5-1 Field of the invention: The present invention relates to a method for isolating integrated circuit elements, and in particular to the improvement of the contour of a grooved side wall in an integrated circuit Isolation structure manufacturing method. 5-2 Background of the Invention: «With the trend of shrinking semiconductor device sizes, in the area of isolation technology, the traditional LOCal Oxidation of Silion (LOCOS) has gradually been isolated by a method called shallow groove isolation ( Shallow Trench I s ο 1 ati 〇n, STI) technology. To make a shallow groove isolation structure, a groove is generally dug on the surface of the substrate as a dividing line for the active area of the component. The manufacturing method of trench isolation usually includes the following steps: firstly, a pad oxide layer is formed on the substrate surface, and a layer of nitride barrier is formed thereon; and then a trench is defined by a photoresist mask Area, followed by etching. First, the nitride barrier layer and the oxide pad layer are etched, and then the substrate is etched to form a groove. The groove can be filled with a dielectric (usually like silicon oxide). The trench filling element is completed. Then, the trench filling is flattened. The planarization is usually performed. Chemical-Mechanical Polishing (CMP) is usually used as the last step, and then nitriding is performed sequentially. Barrier and pad oxide removal

461027

V. Description of the invention (2), that is, the production of the trench isolation structure is completed. Although the traditional trench isolation process has become mature and widely used, driven by the development of the process, we always hope to further simplify the process to increase ancient production capacity. . In view of this, Park et al., In US Patent No. 5,966, No. 14, proposed an improved process to simplify the manufacture of groove isolation. The simplified method is to eliminate the fabrication of the traditional nitrided barrier layer. It is known that the nitride barrier layer is used to block grinding in the traditional process. The method proposed by Parker et al. Is to define and etch a groove structure by masking the nitride-free substrate on the substrate without nitride. The process is briefly described in the first A to F chart. First referring to the first a, it can be seen that a mask pattern 102 (for example, a photoresist pattern) is formed on a semiconductor substrate 100, and this mask pattern is used. 1.0 2 is a button carved mask, directly. OO to a predetermined depth, a recess is formed as shown in the first B diagram. Then, as shown in FIG. _ / C, the curtain pattern 102 is removed. Then, as shown in the first figure d, an insulating substance (for example, silicon oxide) is filled into the groove. The method of filling may be Chemical Vapor Deposition ′. Next, the ditch-filled insulation is planarized by a chemical mechanical polishing process to form the ditch filling material 104 in the figure. However, because the fabrication of the polishing barrier layer (ie, nitride) is omitted in this structure, the polished surface often suffers damage during the polishing process. The remedy method is to use an etching step in a subsequent process (such as a sacrificial oxide process) to etch away a small portion of the abrasive surface material to keep the surface layer as undamaged as possible. For example, the first E picture shows a sacrificial oxide layer 106 (sacrificial oxide

Page 5 461027 V. Description of the invention (3) The formation of ''. '.. As shown in the first F picture, “the hafnium layer 10 is removed, and the oxide layer is removed.” At the same time, a small part of the surface oxide (including the abrasive damaged part) in the groove is also etched away. This removal procedure can be chosen like oxide etchants for hydrogen fluoride (HF). Although the method of Parker et al. Inevitably requires surface layer repair procedures as described above, it is still much simpler than the application of traditional nitrided barrier layers (including the deposition 'etching and removal of nitride layers). And we have found that this simplified STI process is very suitable for the production of high-density semiconductor devices with small line widths in general applications. Existing STI processes (including 'the side walls are mostly near vertical edges with vertical sharp corners, where L is the shape, filled and flat layer'). However, due to the wet ditch in the trenching process, field oxygen is often present The formation of the oxide layer comes from the area where the forming element is correct and reliable. However, the formed grooves cause problems on the grooves. In the grooves, a gate is oxidized through the sacrificial oxygen electrode edges and depressions to cause deposition). This resulted in the straightness of the above-mentioned proposed by Parker et al.). For a vertical-shaped side wall, after the interaction between the upper edge of the groove and the active area of the process for making subsequent components, a steep drop of the side wall is usually deposited above the substrate (especially, this situation is more obvious). The occurrence of the sag of the brake compound occurs, and then the weak phenomenon (thi η ningeffect), its electric field is susceptible to variability and adverse effects. Therefore, we 絷 Iw, ice address π B, and we need to exhibit a simple process to make depressions Trench isolation 'and the concave / a corner upper edge to penetrate the electronic characteristics of the semiconductor element.

4 6 1 ο 2 7 V. Description of the invention (4) 3 Purpose and summary of the invention In view of the many shortcomings caused by the conventional trench isolation in the background of the invention described above, the present invention proposes a method for stepwise electrical failure of the etching process to cause the trench. Concave and ditch isolation with improved edge and wall contours has the dual advantages of simple manufacturing process and improved component performance. In pattern. The thin layer, and the surface material reaction chamber presents a slight concave content in the groove and the embodiment of the polymer insulation and removal, and then the organic polymer material is engraved on the bottom button with an inclined groove shape adjacent to its adjacent film And the light quality, and the completion of the formation of a photoresistive wafer to cover the main reaction of the forming. In the process of the groove, the side wall wheel with a flat screen will be favorable, and the back layer of the special resistance layer will be flattened by the substrate. The concave screen will cover the first guest worm, and the photoresist will pass through when it is polymerized. I carved obstacles and continued concave groove. When the surface is clear. Finally, the trench isolation is first covered in a bottom chamber, and covered with a film in the curtain and exposure chamber. As a result of the use, the worms tend to remove the pits with smooth contents. Then ’perform sacrifice production. After the substrate etching gas from the reaction chamber is formed on the material, the organically etched concave upper edge junction is filled and added, and the surface of the groove formed on the oxide layer of the groove and the wafer are formed. That is, the polymer film groove can be constructed. If you enter here, you can fill in the shape

4 6 10 2 V. Description of the invention (5) 5-4 Detailed description of the invention The following description of the process and structure is not inclusive, and is used to help explain the invention. Moreover, the two-two-in-line = is used for the main scale drawing, its function is only to show the structure of the present invention ": _ shows that the benefits of the present invention can be obtained through the following embodiments and related diagrams a to ii) Explain and reveal. Referring to the second detail, a photoresist pattern 200 is first formed on a semiconductor substrate 200 as an etching mask. Before forming the mask pattern 202, one can also choose to form a thin layer of oxide (not shown) in advance to improve the adhesion between the photoresist pattern and the substrate. Next, this is covered by a curtain. For example, an electric _. Sub-rotating magnetic force Cyclotron Resonance chamber should be etched with etching gas to grow something on the surface of the wafer. The etching gas can be selected from CHF3, CF4, SF6 and other gas chambers. In the controlled environment, chemical reactions occur, and the wafers that cover the photoresist cover, in particular, are placed in an electropolymerized etching reaction chamber accelerated resonance reaction chamber (Electron chamber). An appropriate reaction chamber environment is then formed in the reactor to make the organic polymer. The formation of aggregates on the wafer surface is very diverse, such as C 1 2, HBr, and C 2F 6. The selected etching gas is in the photoresist 202, even with the exposed substrate 200, and the thin polymer 204 to cover the surface of the wafer. Case 20 2 surface (including side edges), such as the second

Page 8 4 6 1 0 2 7 V. Description of the invention (6 plants ^ ^ ^ ^ ^ ---- B). The thickness of this polymer film 〇4 can generally be controlled between 50 and 丨 〇〇〇〇 In addition, 'the skilled person can also adjust the reaction pieces in the reaction chamber, so that the polymer cover is as smooth as possible in the edge zone, so as to facilitate the formation of the grooves. ^ Refer to the second figure C' In the same remaining reaction chamber, anisotropic etching technology is used to etch the substrate from 2000 to a predetermined depth 'to obtain a groove 6 6. As the above polymer 2 〇4 During the etching process, it provides a barrier effect. Therefore, when etching the substrate, we found that the etching rate will change with the depth of the groove etch. Therefore, the shape of the groove contour tends to tilt inward. , As shown in the figure, instead of a nearly vertical shape as in the traditional process. And this slightly inclined profile will facilitate the filling of the subsequent groove contents and the adhesion to the groove surface ^ In addition, this polymer The cover 204 also shields the upper edge of the groove during the groove etching process to make it Free from the frontal etch that bears the brunt, it even imitates the polymer film with smooth edges to make the upper edge of the grooves 6 6 form a smooth outline. This smooth upper edge allows the contents of the grooves 6 6 to be filled in later. It has better contact characteristics with the substrate 200. It is worth noting that the present invention produces a groove structure with an improved profile in only one step of plasma etching. When the groove 66 is formed, then The remaining polymer 204 can be removed, as shown in the second diagram D. Thereafter, the photoresist pattern 200 can also be removed, as shown in the second diagram e.

Page 9 461027 V. Description of the invention (7) Next, referring to the second F figure, the recess, in this embodiment, the filling of the insulation value 206 can be used for insulation / insulation material _ deposition method, and insulation Substance 20 6 is used: suitable deposition process for gas phase or filling with insulating material. Note that before the groove filling can also be used, the trench is deposited by the method (oxide liner). An emulsified liner ^ ^ ^ 〇 ^; Vo'ei f Ϊ f ^ ^ mechanical: grinding technology and flattening, and form a concave two filling: machine 206 as shown in the figure. Those skilled in this door are here In the grinding process, according to the requirements of Zhao ^, adjust the grinding strips, according to the county's tricks: Zuo Dan and Tian Yi ..., the private sequence requires the conditions of π, and try to avoid damage to the surface as much as possible. Ionization, A sacrificial oxide layer 208 is formed. When required by the process, J 70 is completed, and then the sacrificial oxide layer 206 is removed by a wet etching process. As shown in the figure below, the etchant can be hydrogen fluoride. Invented: Two isolation structures have been completed. After that, gate oxide layers, gate electrodes, and other components can be fabricated to complete a product. Circuit making. — The above descriptions are merely preferred embodiments of the present invention, and are not intended to limit the scope of patent application for the present invention; any other equivalent changes or modifications made without departing from the spirit disclosed by the present invention , Should be included in the scope of patent application below.

461027 Schematic illustrations Figures A through F show the traditional manufacturing process of a trench isolation in cross section. The second A to the second figure are cross-sectional views showing a manufacturing process of trench isolation according to one embodiment of the present invention. Representative symbols of main parts: 100 semiconductor substrate 1 0 2 photoresist curtain cover 1 0 4 groove filling layer 1 0 6 sacrificial oxide layer 20 0 semiconductor substrate 2 0 2 photoresist curtain cover 204 organic polymer film 2 0 6 concave Trench filling layer 2 0 8 sacrificial oxide layer 6 6 four trench

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Claims (1)

4 6 10 2 7 6. Scope of patent application 1. A method for manufacturing a trench isolation object, at least comprising: forming a photoresist mask on a semiconductor substrate to define a recess An organic polymer film is formed in the reaction chamber at the touch of a touch. The organic polymer film is formed on the semiconductor substrate to cover the surface and sides of the photoresist curtain. A part of the organic polymer film is passed through The photoresist curtain is generated by the reaction with an etching gas; in the etching reaction chamber, the semiconductor substrate is etched to form a groove; the organic polymer film provides a barrier effect in the etching process, causing the groove The upper edge forms a smooth shape, in which ~ part of the organic polymer is etched away in the etching process; an insulating layer with an oxide is formed in the groove; the insulating layer is chemically and mechanically ground to form a A trench insulation layer is formed in the trench; a sacrificial insulation layer is formed over the semiconductor substrate; and the sacrificial oxide layer is removed by etching. 2. The method according to item 1 of the patent application, wherein the above-mentioned etching reaction chamber includes an electron cyclotron magnetic resonance resonance chamber (El ectron Cyclotron Resona.nce .chamber). 0 3. The method according to item 2 of the patent application. Among them, the above-mentioned etching gas system is one of the following: Cl2, HBr, C2F6, CHF3, CF silicon and SF6. Page 12 4 6 1 〇 2 7 /, Shen Jing patent scope 4.-a kind of grooves rarely include: directly on the substrate, the semiconductor compound film out of the substrate-the etched groove Part of the organic forms a chemical machine trench; forms a manufacturing method for etching isolation (trench isolation), to form a photoresist mask (half channel) to define a groove; etch reaction In the chamber, an organic polymer film is formed on the semiconducting 'the organic polymer film is formed by the photoresist curtain and exposed substrate reacting with an etching gas', wherein the organic polymer has a smooth upper edge region ; In the etching reaction chamber, melting the semiconductor substrate to form a concave polymer film so that the upper edge of the groove is formed into a smooth shape, and the organic polymer is etched away in the etching process; Inside the groove; mechanically grinding the oxide layer to form a groove insulation layer on the concave sacrificial insulation layer over the semiconductor substrate; and removing the sacrificial oxide layer. " "; / Λ 5. The method according to item 4 of the scope of patent application, wherein the above-mentioned etching reaction chamber contains an electron cyclotron magnetic resonance resonance chamber (Electron Cyclotron Resonance chamber) 〇 6. If the scope of patent application item 4 Method, wherein the above-mentioned etching gas system is one of the following: Cl2, .HBr, C2F6, CHF3, CF and SF6. Page 13 461027 6. Scope of patent application 7. The method of the scope of patent application No. 4 further includes removing the remaining organic polymer film after the groove etching process. 8. If the method according to item 4 of the patent application scope, further includes removing the photoresist curtain after the groove etching process. Page 14