TW200531172A - Method of forming an opening - Google Patents

Abstract

A method of forming an opening is provided. A pad oxide layer containing nitrogen is formed on a substrate. Then, a patterned mask layer is formed on the pad oxide layer containing nitrogen. The pad oxide layer containing nitrogen and the substrate are etched by using the patterned mask layer as etching mask to form an opening in the substrate. Since the etching resistibility of the pad oxide layer containing nitrogen is better than that of a pad oxide layer in prior art, the undercut issue of the pad oxide layer at the sidewalls of the opening can be avoided in subsequent etching processes.

Description

200531172 V. Description of the invention (1) Technical field to which the invention belongs The present invention relates to a semiconductor process, and more particularly to a method for forming an opening. Prior art In semiconductor manufacturing, the formation of openings is one of the process steps that are often performed. Generally, a method for forming an opening in a substrate is to form a pad oxide layer on the substrate, and then form a patterned silicon nitride mask layer on the pad oxide layer, and then use the silicon nitride mask layer as an etching mask. The pad oxide layer and the substrate are sequentially etched to form openings in the substrate. After that, according to the needs of different processes, other processes are sequentially performed to complete the production of deep trench capacitors (Shallow Trench Isolation, STI), and so on. For deep trench capacitors, when a deep trench (ie, an opening) is formed in the substrate, the lower electrode, the capacitor dielectric layer, and the upper electrode are sequentially processed in the deep trench. In the above processes, it is inevitable that some etching reactants will be used to define the film layer, clean the film layer, or remove the film layer. These etching reactants are, for example, diluted hydrofluoric acid. (Diluted HF, DHF), buffered hydrofluoric acid (Buffer HF, BHF) or ethylene glycol solution of hydrofluoric acid (HF / EG), etc. Compared with the silicon nitride film, these etching reactants have a higher removal rate for the silicon oxide film. Therefore, the above-mentioned film definition, film cleaning or film removal are being performed, etc. During the step, the underlayer is more prone to undercut than the silicon nitride mask. In other words, the exposed pad oxide layer on the side wall of the deep trench can cause

12895TWF.PTD Page 5 200531172 Fifth, the description of the invention (2) of the invasion, and gradually removed, and then a depression (Recess). The depression of the hafnium oxide layer may cause the mask layer to peel off, which will affect the subsequent processes, or it should be filled only in deep trenches as a conductive material for the upper electrode, and filled into the depression of the oxide layer. And left in it, which causes the problem of short circuit of the component. SUMMARY OF THE INVENTION In view of this, an object of the present invention is to provide a method for forming an opening, so as to solve the problem that when the opening is formed, the pad oxide layer on the sidewall of the opening is caused by the use of an etching solution having a high removal rate for the pad oxide layer. Undercut issues. Another object of the present invention is to provide a method for forming an opening to solve the problem that after the opening is formed, the pad oxide layer on the sidewall of the opening is caused by using an etching reactant having a high removal rate for the pad oxide layer in a subsequent process. Undercut issues. Another object of the present invention is to provide a method for forming an opening, so as to solve the problem of the side wall of the opening caused by the use of a money-etching reactant having a high removal rate for the pad oxide layer when the opening is formed and after the opening is formed. Pad undercut problem. The present invention provides a method for forming an opening. The method for forming the opening is to form a nitrogen-containing pad oxide layer on a substrate. Then, a patterned mask layer is formed on the nitrogen-containing pad oxide layer. Next, using the patterned mask layer as an etching mask, the nitrogen-containing pad oxide layer and the substrate are etched to form an opening in the substrate. Because the nitrogen-containing pad oxide layer of the present invention is compared with the conventional pad oxide layer

12895TWF.PTD Page 6 200531172 V. Description of the invention (3) It has better resistance to etching, that is, the etching reactant has a lower removal rate for the nitrogen-containing pad oxidation layer. Therefore, it is known that the undercut of the pad oxide layer caused by the remaining reactants invading the pad oxide layer can be solved. The present invention provides another method for forming an opening. This method first provides a substrate, and a patterned pad oxide layer and a mask layer have been formed on the substrate, and the surface of the substrate is exposed. Then, a nitriding step is performed to nitride the exposed sidewalls of the pad oxide layer to form a oxynitride layer. Next, an etching step is performed using the mask layer as an etching mask to form an opening in the substrate. Because the pad oxide layer at the side wall of the opening of the present invention has an additional layer of oxynitride stone compared to the conventional pad oxide layer, and the oxynitride fragment layer can effectively block the erosion of the etching reactant, that is, the etching reactant against nitrogen The silicon oxide layer has a lower removal rate. Therefore, it is known that the problem of undercutting the pad oxide layer caused by the etching reaction material etching the pad oxide layer can be solved. The present invention provides another method for forming an opening. This method first provides a substrate, and a patterned pad oxide layer and a mask layer have been formed on the substrate, and the surface of the substrate is exposed. Then, using the mask layer as an etching mask, an etching process is performed to form an opening in the substrate. Next, a protective layer is formed on the sidewall of the opening, and the protective layer covers at least the exposed sidewall of the mask layer and the pad oxide layer. Because the pad oxide layer at the side wall of the opening of the present invention is more covered with a protective layer than the conventional pad oxide layer, and this protective layer can effectively block the erosion of the etching reactant, that is, the etching reactant has a lower protection layer. Removal rate. Therefore, it is known that the oxide of the pad is eroded by the etching reaction,

12895TWF.PTD Page 7 200531172 V. Description of the Invention (4) The problem of undercut of the pad oxide layer can be solved. In addition, the above-mentioned several methods for forming the openings can be applied to the process of deep trench capacitors to improve the anti-etching ability of the hafnium oxide layer on the side walls of the deep trench (ie, the opening), thereby solving the conventional mask layer peeling. Or the problem that the conductive material remains in the recess of the undercut pad oxide layer. In order to make the above and other objects, features, and advantages of the present invention more comprehensible, the preferred embodiments are described below in detail with the accompanying drawings, as follows. Embodiments First Embodiment FIGS. 1A to 1D are schematic cross-sectional views illustrating a process of forming an opening according to a first embodiment of the present invention. First, referring to FIG. 1A, a pad oxide layer 102 is formed on a substrate 100. The substrate 100 is, for example, a silicon substrate, and the material of the pad oxide layer 102 is, for example, silicon oxide, and the formation method is, for example, a thermal oxidation method. Then, referring to FIG. 1B, a nitriding step 104 is performed to nitride the pad oxide layer 102 to form a pad oxide layer 106 containing nitrogen. The nitriding step 104 is performed, for example, in a deposition reaction chamber, and the reaction gas used includes a nitrogen-containing gas, such as ammonia, and the nitriding temperature thereof is, for example, between 760 ° C and 800 ° C. between. Moreover, the degree of nitridation of the nitrogen-containing pad oxide layer 106 is, for example, gradually decreased from the top to the bottom of the nitrogen-containing pad oxide layer 106. In addition, the relevant parameters of the nitriding step 104 are not particularly limited, and their end depends on different process requirements, that is, as long as the formed nitrogen-containing pad oxide layer 106 can resist subsequent silicon oxide Etching

12895TWF.PTD Page 8 200531172 V. Description of Invention (5) ^ ----- The invasion of the name should be enough. Ϊ ί Ϊ: Because the silicon nitride material is 100% for silicon substrates, it is easy to get in and out of the Three Valleys. Therefore, the use of a whole layer of nitrided stone formed by the present invention is compared to The problem of f 106 peeling on the substrate 100. This is achieved by the formula "#", which can avoid nitrogen-containing hafnium oxide layer, which can be avoided. Because of the nitrogen-containing pad oxide layer of the present invention 106 ^ e ^ a ^^. Even if the content is relatively high, the film layer can be released * two or two, and the farther away from the nitrogen-containing pad oxide layer 106 of the substrate 100 is, the better the anti-etching ability can be provided. Curtain material: 108 ′ two-picture cover 1V material in Shixi, and its formation method is, for example, material Λ108 material such as gasification reaction gas such as ammonia gas and Erxue vapor deposition method, and is used 2ci2). It is worth mentioning that the formation of upper = chlorosilane (Dichlorosilane, SiH 108) can be performed in the same reaction chamber as the nitridation step 104 and the curtain material. The reaction chamber can be laminated in advance. Nitrogen gas, which is, for example, ammonia gas, enters the chemical vapor deposition reaction chamber, and then passes through the nitriding oxide layer 102 containing the mask material layer 108, and then continues, please refer to FIG. 1D. Then, the patterned mask layer 108a is then patterned. Then the mask material layer 108 is patterned to form an etch mask, and the nitrogen-containing cushion air flap is etched = the patterned mask layer 1 08a is at the bottom. The opening 11 is formed. The emulsified layer U6 and the substrate 100, and in the above-mentioned process, the oxidized layer 106 of the dead body cushion has better resistance to etching than the exposed nitrogen-containing oxide layer on the side wall of the conventional pad 1 10 can

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苐 Page 200531172 V. Description of the invention (6) The force ′, that is, the etching reactant for silicon oxide, has a lower removal rate for the pad oxide layer 106 containing nitrogen. Therefore, it is possible to avoid the problem of undercutting the pad oxide layer in the subsequent processes due to the use of the money-etching reactants for the oxide stone. Second Embodiment FIGS. 2A to 2C are schematic cross-sectional views illustrating a process of forming an opening according to a second embodiment of the present invention. First, referring to FIG. 2A, a nitrogen-containing pad oxide layer 200 is formed on the substrate 200. The substrate 200 is, for example, “Yes” Shixi substrate, and the material of the nitrogen-containing pad oxide layer 200 is, for example, silicon oxynitride. The formation method is, for example, a thermal oxidation process, and the thermal oxidation process is performed here The middle system is formed by introducing gas and nitrogen-containing gas. Wherein, the nitrogen-containing gas includes nitrous oxide (Nζ〇), and the mixing ratio of the nitrous oxide and oxygen is not particularly limited, and its end depends on different process requirements, that is, as long as the formed The nitrogen pad oxide layer 200 can resist the subsequent etching of silicon oxide by the etching reactants. Then, referring to FIG. 2B, a patterned mask layer 204 is formed on the nitrogen-containing pad oxide layer 202. The material of the patterned mask layer 204 is, for example, rhenium fossil, and the method of forming the mask layer 204 is, for example, forming a mask material layer (not shown) on the nitrogen-containing tritium oxide layer 002, and then performing a lithography process And money engraving process. Χ Next, referring to FIG. 2C, using the patterned mask layer 204 as an etching mask, the nitrogen-containing pad oxide layer 202 and the substrate 200 are sequentially etched to form an opening 2 in the substrate 200. . In the above process, due to the exposed nitrogen-containing

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Page 10 200531172 V. Description of the invention (7) The pad oxide layer 2 0 2 has better resistance to etching than the conventional pad oxide layer, that is, the silicon oxide etching reactant against the pad oxide layer containing nitrogen 2 0 2 Has a lower removal rate. Therefore, the problem of undercutting of the pad oxide layer in the subsequent process can be avoided. Third Embodiment FIGS. 3A to 3B are schematic cross-sectional views illustrating a process of forming an opening according to a third embodiment of the present invention. First, referring to FIG. 3A, a substrate 300 is provided, and a patterned pad oxide layer 302 and a mask layer 304 have been formed on the substrate 300, and the surface of the substrate 300 is exposed. The substrate 300 is, for example, a silicon substrate, and the material of the patterned pad oxide layer 302 is, for example, stone oxide, and the material of the patterned mask layer 304 is, for example, nitride stone. Then, a nitriding step 301 is performed to degrade the sidewalls of the exposed pad oxide layer 302. At this time, the surface of the substrate 300 is also nitrided at the same time to form a gas oxide layer 306 and a gasified stone. Evening layer 307. The reaction gas used in the nitriding step 301 is, for example, oxygen 'and its nitriding temperature is approximately 950 ° C. In addition, the limitation of the relevant parameters of step 301; the limitation depends on the requirements of different processes. A high ..., special silicon oxynitride layer 3 06 can resist the subsequent erosion of a \ P as long as it is formed. 1 etched silicon reactant = 耆, please refer to the figure w, μ dry ♦ 〇 304 is the etching step, which is, for example, an anisotropic etching! An opening 3 08 is formed in the curtain order. Among them, because it is located on the substrate, and the thickness of the silicon layer 300 on the substrate 300 is very thin, the nitride on the anisotropic cooking surface removes the silicon nitride layer 3 07, and then the substrate can be easily etched. J 丞 展 3 〇〇 to form an opening

200531172 V. Description of the invention (8) 3 0 8 ° In the above process, due to the art oxide layer 30 on the side wall of the opening 308, compared with the conventional pad oxide layer, there is an additional silicon nitride oxide layer 3 06, and this The silicon oxynitride layer 3 0 6 can effectively block the contact of the etching reactant against silicon oxide, that is, the reactant has a lower removal rate for the nitrogen oxynitride second layer 3 6 against the stone oxide evening. Therefore, the problem of undercutting of conventional oxide pads can be solved. & Fourth Embodiment FIGS. 4A to 4B are schematic cross-sectional views illustrating a process of forming an opening according to a fourth embodiment of the present invention. First, referring to FIG. 4A, a substrate 400 is provided, and a patterned pad oxide layer 402 and a mask layer 404 have been formed on the substrate 400, and the surface of the substrate 400 is exposed. The substrate 400 is, for example, a silicon substrate, the material of the patterned pad oxide layer 402 is, for example, stone oxide, and the material of the patterned mask layer 400 is, for example, silicon nitride. Then, referring to FIG. 4B, using the mask layer 400 as an etching mask, an etching step is performed to form an opening 4 06 in the substrate 400. Next, a protective layer 408 is formed on the side wall of the opening 406, and the protective layer 408 covers at least the exposed side walls of the cover curtain layer 404 and the pad oxide layer 402. The material of the protective layer 408 is, for example, a nitrogen-containing material, such as silicon nitride, and the formation method thereof is, for example, a plasma enhanced chemical vapor deposition (PECVD) process. It is worth mentioning that, because the plasma-enhanced chemical vapor deposition method has a higher horizontal deposition rate than a vertical deposition rate, a protective layer as shown in FIG. 4B will be formed.

12895TWF.PTD Page 12 200531172 V. Description of the invention (9) 4 0 8. In other words, the protective layer 408 at the sidewall of the opening 406 will become thinner as the depth of the opening 406 becomes deeper. In a preferred embodiment, if the protective layer 408 forms a film layer of about 100 angstroms on the cover layer 404, the thickness of the protective layer 408 at the side wall of the opening 406 is approximately It is about 18 to 21 angstroms, and the protective layer 408 can only be formed to the opening 406 depth (D 1) 0.5 micron. In the above process, the pad oxide layer 402 at the side wall of the opening 406 is covered with a protective layer 408 more than the conventional pad oxide layer, and the protective layer 408 can effectively block the etching reactants for silicon oxide. Erosion, that is, the etching reactant for silicon oxide has a lower removal rate for the protective layer 408. Therefore, the conventional undercut problem of the pad oxide layer can be solved. The method for forming an opening in the fourth embodiment described above can be applied to the manufacturing process of a deep trench capacitor. The detailed description is as follows. 5A to 5F are schematic cross-sectional views illustrating a manufacturing process of a deep trench capacitor. It is worth noting that, in the manufacturing process of this deep trench capacitor, although the manufacturing of the deep trench is described in detail by using the opening forming method of the fourth embodiment, it is not intended to limit the present invention, that is, The manufacturing of deep trenches can also be performed in the manner described in the first embodiment, the second embodiment, or the third embodiment. First, referring to FIG. 5A, a patterned liner layer 502 and a mask layer 504 are formed on a substrate 500. The substrate 500 is, for example, a silicon substrate, and the material of the patterned pad oxide layer 502 is, for example, silicon oxide, and the material of the patterned mask layer 504 is, for example, silicon nitride. Then, using the mask layer 5 0 4 as an etching mask, an etching step is performed to form a deep trench (ie, an opening) in the substrate 5 0 6 °

12895TWF.PTD Page 13 200531172 V. Description of the invention (ίο) Next, a protective layer 5 0 8 is formed on the side wall of the deep trench 5 0 6, and the protective layer 508 covers at least the cover curtain layer 504 and the pad oxide layer 5 2 Of the exposed sidewalls. The material of the protective layer 508 is, for example, a material containing nitrogen, which is, for example, silicon nitride, and the formation method thereof is, for example, a plasma enhanced chemical vapor deposition process. The detailed description of the protective layer 508 is the same as that of the protective layer 408 of the fourth embodiment, and is not repeated here. After that, a doped insulating layer 5 10 is formed on the side wall of the deep trench 506 to cover the side wall of the deep trench 506 and the protective layer 508. The material of the doped insulating layer 5 1 10 is, for example, a oxidized stone layer doped with arsenic ions, and the method of forming the doped insulating layer 510 is, for example, chemical vapor phase by in-situ doping ions. Deposition process. Next, a photoresist layer 5Π is formed at the bottom of the deep trench 5 06, wherein the photoresist layer 5 1 1 does not fill the deep trench 5 0 6 and the surface of the photoresist layer 5 1 1 is located on the surface of the substrate 5 0 0 Below 50 0a. Then, referring to FIG. 5B, a part of the doped insulating layer 5 1 0 that is not covered by the photoresist layer 5 1 1 is removed to form a doped insulating layer 5 1 0 a. The method for removing the doped insulating layer 5 10 is, for example, a wet-etching method, which uses a buffered hydrofluoric acid (Buffer HF, BHF) or a diluted hydrofluoric acid (Diluted HF, DHF) as an etching solution. . Since the pad oxide layer 5 0 2 on the side wall of the deep trench 5 06 is covered with the protective layer 5 0 8, the etching solution does not attack the pad oxide layer 5 2. Next, after the photoresist layer 511 is removed, a conformal insulating layer 5 12 is formed on the substrate 500 to cover the sidewalls of the protective layer 508, the insulating layer 5 10a, and the deep trench 506. The material of the insulating layer 5 1 2 is, for example, Tetra Ethyl Ortho Silicate (TEOS) / ozone (03).

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The reaction gas source is oxidized by the chemical vapor deposition process. In addition, the purpose of forming the insulating layer 5 1 2 here is to prevent the dopant of the doped insulating layer 5 1 0 from diffusing to the predetermined Collar Oxide Layer during the subsequent thermal process (ie, The doped insulating layer 510a ^) is adjacent to the substrate 500. 5C, a thermal process is performed to diffuse impurities in the doped insulating layer 510a into the substrate 500 at the bottom of the deep trench 506 to form a doped region 5 1 4 and this doped region 5 14 is used as the lower electrode 5 1 4 of the deep trench capacitor. In addition, it is worth mentioning that since the protective layer 5 08 and the insulating layer 5 1 2 are formed at the side wall of the deep trench 5 06, the diffusion of the dopants in the impurity insulating layer 510a can be blocked, and the doped region 514 can be blocked. Do not spread too much. In particular, the formation of the protective layer 508 can more effectively block the diffusion of dopants in the doped insulating layer 510a, so that the lower electrode 514 is limited to a range surrounding the bottom of the trench 506. Then, the doped insulating layer 5 1 0 a and the insulating layer 5 1 2 at the bottom of the deep trench 5 0 6 are removed. The removal method is, for example, a wet etching method, which is performed by using buffer HF (BHF) or Diluted hydrofluoric acid (Diluted HF, DHF) is an etching solution. Similarly, since the pad oxidation layer 502 on the side wall of the deep trench 506 is covered with the protective layer 508 at this time, the etchant does not attack the pad oxidation layer 502. 5D, a capacitor dielectric layer 516 and a conductive layer 518 are sequentially formed at the bottom of the deep trench 506. The material of the capacitor dielectric layer 516 is, for example, silicon oxide / silicon nitride, and the material of the conductive layer 5 1 8 is, for example, doped polycrystalline silicon or polycrystalline silicon. About the manufacturing process of the capacitor dielectric layer 516 and the conductive layer 518

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This is the percentage of the m artist, so I won't repeat it here. Oxidation $ ^ 20 '. & / ^ Man layer 5 0 8 and the surface of deep trench 5 06 form a conformal collar chemistry. The method of forming the collar oxide layer at a deposition process of 52 ° is, for example, Λ acid. The reaction gas is, for example, ozone. / Tetraethyl Shixu field u si following ± 'Refer to Figure 5 E' Remove the conductive oxide layer β 2 and the conductive oxide layer β 2 5 which is located above the mask layer 5 0 4 and leave only the deep trench 5 〇6 sidewall ί ί the layer 5 2 〇a 'The method of removing the collar oxide layer 5 2 0 is, for example, performing an anisotropic etching process. / Then / fill the conductive layer 5 2 in the deep trench 5 0 6 2, and the conductive layer 5 2 2 / 糸 is electrically connected to the conductive layer 518. Among them, the material of the conductive layer 5 2 2 is ^ ^ replaced with polycrystalline silicon or polycrystalline silicon, and its formation method is familiar with this technology Known here will not repeat the details here. Next, please refer to FIG. 5F, remove the collar oxide layer 52〇a not covered by the conductive layer 5 2 2 to form a collar oxide layer 5 20 b. After that, Yu Shen The trench 5 0 6 = becomes a conductive layer 524. Among them, the material of the conductive layer is, for example, doped poly = Shi Xi or polycrystalline Shi Xi 'and the conductive layers (518, 5 2 2 and 5 24) are connected to each other. The common connection is: 1 is used for the electrode on the deep trench capacitor. Y. In the above process, 'due to the completion of the fabrication of the deep trench 506 in FIG. 5A, the protective layer is covered at the side wall of the oxide layer 502.饨 刿; 5 臛 舲 *, the process of Fig. 5B to Fig. 5F will use a combination of film layer definition, film cleaning, or film removal for the oxidized stone and so on. 2 will not be subject to the & cut problem of the reactant carved by this surname. Therefore, when filling in the deep trench 5 06

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Page 16 200531172 V. Description of the invention (13) When the conductive layer 518, 522 or 524 is used, the conductive material will not fill the recess of the pad oxide layer 502, so the problem of short circuit of the component can be avoided. In summary, the present invention has at least the following advantages: 1. In the first embodiment and the second embodiment of the present invention, the nitrogen-containing hafnium oxide layer has better anti-etching than the conventional hafnium oxide layer. Ability, that is, the reaction rate for the oxidized stone Xi Yu has a lower removal rate of the nitrogen-containing plutonium oxide layer. Therefore, it is known that the problem of undercut of the pad oxide layer can be solved. 2. In the third embodiment of the present invention, the pad oxide layer at the side wall of the opening has an additional layer of oxynitride compared with the conventional pad oxide layer, and the silicon oxynitride layer can effectively block the silicon oxide layer. The erosion of the etch reactant, that is, the etch reactant for silicon oxide has a lower removal rate for the silicon oxynitride layer. Therefore, the problem of undercutting of conventional oxide pads can be solved. 3. In the fourth embodiment of the present invention, the pad oxide layer on the side wall of the opening is covered with a protective layer more than the conventional samarium oxide layer, and the protective layer can effectively block the etching reaction of silicon oxide. Erosion, ie, etch reactants for silicon oxide, have a lower removal rate for the protective layer. Therefore, it is known that the problem of undercutting of the pad oxide layer can be solved. 4. The methods for forming several openings of the present invention can be applied to the manufacturing process of deep trench capacitors to improve the anti-etching ability of the pad oxide layer on the side walls of the deep trench (ie, the opening), thereby solving the conventional mask layer peeling. Or the problem that the conductive material remains in the depression of the pad oxide layer. In particular, using this

12895TWF.PTD Page 17 200531172 V. Description of the invention (14) The protective layer formed by the method of the fourth embodiment of the invention can not only protect the pad oxide layer on the side wall of the deep trench, but also avoid the lower electrode process. At this time, the dopant diffuses into the substrate adjacent to where the collar oxide layer is intended to be formed. 5. The methods of forming the openings of the present invention are not limited to the application of the manufacturing process of deep trench capacitors. Other processes that also need to form openings can also use the method of forming the openings of the present invention. Although the present invention has been disclosed in the preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and retouching without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be determined by the scope of the attached patent application.

12895TWF.PTD Page 18 200531172 Brief Description of Drawings Figures 1A to 1D show schematic cross-sectional views of a process for forming an opening according to a first embodiment of the present invention. 2A to 2C are schematic cross-sectional views illustrating a process of forming an opening according to a second embodiment of the present invention. 3A to 3B are schematic cross-sectional views illustrating a process of forming an opening according to a third embodiment of the present invention. 4A to 4B are schematic cross-sectional views illustrating a process of forming an opening according to a fourth embodiment of the present invention. 5A to 5F, which are schematic cross-sectional views illustrating a manufacturing process for applying a method according to a fourth embodiment of the present invention to form a deep trench capacitor. [Explanation of figure mark] 100, 2 0 0, 3 0 0, 4 0 0, 5 0 0 · · substrate 102, 302, 402, 502: pad oxide layer 1 0 4, 3 0 1: nitriding step 106, 202: Nitrogen-containing pad oxide layer 08: Mask material layer 108a, 204, 3 04, 40 4, 50 4: Mask layer 110, 206, 308, 406: Opening 3 0 6: Nitrogen Silicon oxide layer 3 0 7 •• Nitride layer 4 0 8、5 0 8: Protective layer 500 a: Substrate surface 5 0 6: Deep trench 5 1 0, 5 1 0 a: Doped insulating layer

12895TWF.PTD Page 19 200531172 Brief description of the drawings 5 1 1: Photoresistive layer 5 1 2: Insulating layer 5 1 4: Doped region (lower electrode) 516: Capacitive dielectric layer 518, 522, 524: Conductive layer 520 , 520a > 520b: collar oxide layer D1: depth ΙΙΙΒΙΗΙ 12895TWF.PTD p.20

Claims (1)

200531172 VI. Application Patent Scope 1. A method for forming an opening, comprising: forming a nitrogen-containing pad oxide layer on a substrate; forming a patterned mask layer on the nitrogen-containing pad oxide layer; and using the The patterned mask layer is an etching mask, which etches the nitrogen-containing pad oxide layer and the substrate, and forms an opening in the substrate. 2. The method for forming an opening according to item 1 of the scope of the patent application, wherein the method for forming the nitrogen-containing pad oxide layer and the patterned mask layer includes: forming a pad oxide layer on the substrate; performing a The nitriding step is performed to nitride the hafnium oxide layer to form the nitrogen-containing pad oxide layer; forming a mask material layer on the nitrogen-containing hafnium oxide layer; and patterning the mask material layer. 3. The method for forming an opening as described in item 2 of the scope of patent application, wherein the degree of nitridation of the nitrogen-containing pad oxide layer gradually decreases from the top of the nitrogen-containing pad oxide layer to the bottom thereof. 4. The method for forming an opening as described in item 2 of the scope of patent application, wherein the reaction gas used in the nitriding step includes a nitrogen-containing gas. 5. The method for forming an opening as described in item 4 of the scope of the patent application, wherein the nitrogen-containing gas includes ammonia. 6. The method for forming an opening as described in item 2 of the scope of the patent application, wherein the method for forming the mask material layer includes performing a chemical vapor deposition process, and the nitriding step is the same as the chemical vapor deposition process reaction 12895TWF.PTD Page 21 200531172 VI. Scope of patent application. 7. The method for forming an opening as described in item 1 of the scope of patent application, wherein the method for forming the nitrogen-containing pad oxide layer includes performing a thermal oxidation process, and introducing oxygen and a nitrogen-containing gas into the thermal oxidation process. gas. 8. The method for forming an opening as described in item 7 of the scope of patent application, wherein the nitrogen-containing gas includes nitrous oxide (N20). 9. A method for forming an opening, comprising: providing a substrate on which a patterned pad oxide layer and a mask layer have been formed and exposing the surface of the substrate; performing a nitriding step to place the pad The exposed sidewalls of the oxide layer are nitrided to form a silicon oxynitride layer; and using the mask layer as an etching mask, an etching step is performed to form an opening in the substrate. 10. The method for forming an opening according to item 9 in the scope of the patent application, wherein the reaction gas used in the nitriding step includes ammonia gas. 1 1. The method for forming an opening as described in item 9 of the scope of patent application, wherein the nitriding step further includes nitriding the exposed surface of the substrate, and forming a silicon nitride layer on the surface of the substrate, and performing the During the etching step, the silicon nitride layer on the surface of the substrate is removed together. 12. A method for forming an opening, comprising: providing a substrate on which a patterned pad oxide layer and a mask layer have been formed, and exposing the surface of the substrate; using the mask layer as a money engraving Masking, performing an engraving process to form an opening in the substrate; and 12895TWF.PTD Page 22 200531172 6. Scope of patent application A protective layer is formed on the side wall of the opening, and the protective layer covers at least the exposed side wall of the cover layer and the pad oxide layer. 1 3. The method for forming an opening as described in item 12 of the scope of patent application, wherein the material of the protective layer includes a nitrogen-containing material. 14. The method for forming an opening as described in item 13 of the scope of the patent application, wherein the nitrogen-containing material includes silicon nitride. 1 5. The method for forming an opening as described in Item 12 of the scope of the patent application, wherein the method for forming the protective layer includes performing a plasma enhanced chemical vapor deposition (PECVD) process. 12895TWF.PTD Page 23