TW424279B - Chemical etching method for removing hard mask in semiconductor process - Google Patents

Abstract

The present invention discloses a chemical etching method for removing a hard mask in a semiconductor process, particularly for etching SiON. The method is implemented by two steps: removing SiON by a low energy dry etching, and completely removing the SiON by a hot phosphoric acid wet etching. The above mentioned method can increase the etching rate of SiON for further carrying out the HSG step. The present invention not only can generate better etching effects for SiON hard mask, but also can be used for other thin hard mask such as SiN film in etching process.

Description

42 ^ 279- V. Description of the invention (1) 5-1 Field of invention:

The present invention relates to a method for etching. 5-2 Invention of removing the hard mask in the process of the prism bell semiconductor. BACKGROUND OF THE INVENTION In the process of the random memory process, as the process technology advances, especially in the dynamic random memory process, it will increasingly tend to Extremely small, foreseeable, atomic dimensions of future elements. The current line width p% & system ^ S + 4 micron width, such as 0.18 microns. : Tn Semiconductor's high degree of accumulation is moving forward. Looking back on the past ten years or so, since the birth of the computer, the amount of f has increased rapidly due to the widespread use of random memory (Ram) in each phase. Especially used in the telecommunications industry of electronic hardware. At the same time, it is not only used in the information industry, it is also commonly used in large integrated circuit (LSI), very large integrated circuit (VLSI), and ultra large integrated circuit (ULSI). Undoubtedly, even in the next century, the process technology of random memory (RAM) still occupies a very important position in the information industry. In the process, chemical etching technology (Chemical to chemical conversion) is one of the indispensable steps. Generally, when the hard mask of the stomach is removed, such as silicon nitride ( S13), silicon oxynitride (SiON) and silicon oxide (Si02), most of which are heated phosphoric acid (IPO4) heated to 800 ^

笫 Page 4 5. Description of the invention (2)) As the silver engraving solution in the process for removal. The disadvantage of using an oxygen cut as a hard mask for the insulation layer is that the silicon layer is ticked in the layer below the capacitor, and this thin silicon nitride layer is easier to remove oxidized oxide or capacitor over-etching (0veretching). It will also be used at the same time-and therefore, silicon nitride or silicon oxynitride compounds are often used as hard masks in the manufacturing process. As mentioned above, although the oxynitride compound is better for the overall process, if the oxynitride compound cannot be completely removed during the process of removing the oxynitride compound, it will further hinder the growth of hemispherical crystals. Generally, silicon oxynitride compounds can be removed by wet etching, such as hot phosphoric acid, or dry etching. For a long time, the effect of hot phosphoric acid is not easy to grow into a hemispherical junction f 'of the required size, and the capacitance will be reduced. Therefore, in order to try to obtain a better selective hemispherical junction, the wet etching method of hot phosphoric acid is used to complete the etching process. However, the time for hot phosphoric acid to etch the oxynitride compound is about 80 Angstroms / minute, so it will take a considerable time to remove the oxynitride compound. The traditional method will produce bad selective hemispherical crystals, because its energetic atoms (Radicals) will penetrate through the surface of silicon (a-S i 1 ic ο η), making silicon atoms unable to migrate Instead, selective hemispherical crystals are formed. This slow engraving speed and the generation of poorly selective hemispherical crystals' will indeed seriously affect the high requirements and high yield of the process. As mentioned above, “In view of the need to improve and improve the process technology of random dynamic memory (DRAM), it is urgent to propose a new process method and structure to improve the above problems” and improve component quality and manufacturing efficiency. V. Description of the invention (3) 5-3 Purpose of the invention and summary of the background of the invention In the background of the invention described in the traditional wet phosphoric acid phosphoric acid etching method to cover many disadvantages, the present invention is based on two steps The dry-etching method such as energy is used to remove the nitrogen-oxygen compound, and then the wet-etching method is used to remove the nitrogen-oxygen compound. The invention relates to a method for removing a nitroxyl δ substance in a dynamic random access memory system. The steps are as follows: the nitrogen oxide silicon compound is carved with a low-energy dry surname, so that the thickness of the nitrogen oxide silicon compound reaches About less than 100 Angstroms. The above-mentioned low-energy dry etching method is a densification etching method with a high nitrogen oxide silicon compound / silicon claw 2) etching selection ratio. At the end, the oxynitride | s.! _N with a thickness of less than about 100 angstroms is etched by a wet etching method using thermal lithography, so as to completely remove the silicon oxynitride. The wet etching time is about ν in 300 seconds and the etching rate of the wet etching is about 80 angstroms per minute. Method ίΐ: Yu ΓίΠ to increase the fabric of nitrogen and oxygen compounds, followed by ==; ΓΓ crystal step. In addition, the present invention also includes a method of silicon buckets, and the above method. The present invention provides a method to increase nitrogen and oxygen, such as the time of silver engraving, which is less than 300 seconds. And there is no energetic :: and plutonium production, so it will not penetrate through the spherical crystals on the surface of silicon atoms. The present invention is not only applied to the compound w ', but can also be applied to nitrite and oxynitride in the remaining processes.

Page 6 Description of the invention ⑷ a thin hard mask on the cheek. Obviously this and other items #, the features and advantages can be explained in more detail: M, the preferred embodiments are listed below in conjunction with the attached drawings, for details] ~ 4 diagrams briefly explain: The first diagram of the implementation of the present invention flow chart. The second A to the second D patterns are the main etching parts of the present invention. The representative symbols of the main part of the figure of the present invention: 21 oxynitride silicon compound 22 hemispherical crystal 21 semiconductor substrate 211 Shallow Trench Isolation 212 Gate 'or word line 213 bit line 214 Capacitor Contact, or Capacitor Contact 215 Amorphous-Silicon, also a capacitor (

Capacitor) 21 6 A '2 1 6B Inner-Layer Di e 1 ectr i c)

424279 Fifth invention description (5) ~ 5 invention detailed description Fan structure: j i invention: ξ ί. The description of the present invention will first be described in conjunction with the manufacturing and the advantages of the present invention will be described later. The earth-moving method will be discussed later. Limitations Although the present invention is illustrated by one embodiment, this description does not limit the scope or application of the present invention. In contrast, the main parts may be related parts. The semiconductor elements of the invention do not limit the description of the structure. To prove the practicability of the present invention and the preferred embodiment presented in random memory, especially dynamic random memory, in the process of etching the capacitor, the present invention is implemented in two steps, as shown in the flow of the first figure = · Remove nitrogen oxide silicide by low energy dry etching method as shown in the first figure 101. Second, the wet-etching method of the first figure 102 is used to completely remove the silicon oxynitride compound. Finally, the hemispherical crystallization process as shown in the first figure 103 is performed. In addition, a second figure is provided for detailed explanation. The symbols in the figure are: 21 is the oxitride compound, 22 is a hemispherical crystal, 2 10 is a semiconductor substrate, 2 11 is Shallow Trench Isolation, and 212 is a gate. Or word line, 213 is bit line, 214 is capacitive contact window (Capacitor Contact), or node contact window (Capacit〇r

Contact), 215 is Amorphous-Silicon, also Capacitor, and 216A, 216B are internal dielectric layers (

Page 42 42421 § V. Description of the invention (6);

Inter-Layer Dielectric). Therefore, in Figure A, the plasma gas with low energy and high nitrogen oxide silicon compound / silicon dioxide (SiON / SiO2) etching selection ratio is used as a dry etching method to remove the capacitor located in the amorphous silicon 21 5 On the other hand, the oxynitride layer 2 with a thickness of 800 angstroms and most of the oxynitride silicon hard mask can be removed by the low-energy atomic group of the dry bismuth etching method. However, the thickness of the remaining oxynitride layer is less than 100 angstroms. In the second figure B, the wet etching method using thermal phosphoric acid β, this thermal phosphoric acid can remove the remaining silicon oxynitride layer 21 having a thickness of less than 100 angstroms. Therefore, the process time is less than 800 seconds of traditional technology, and only about 300 seconds. At this time, the etching rate of the hot phosphoric acid is about 80 angstroms per minute, and the oxynitride layer 2 1 ′ can be completely removed at the end as shown in the second C figure, without affecting the capacitance of the amorphous silicon 2 5. As shown in the second figure D, Amorphous Silicon is placed in a low-pressure chemical gas deposition reactor (LPCVD) under the conditions of 0.5 to 1 torr and 510 ° C to 5 50 ° C. After the treatment, the natural oxide layer (Native Oxide Layer) was removed by using a “dii—wet cleaning method” and a dilute concentration of 1% hydrofluoric acid (Diiute HF). It was then loaded into a chemical vapor deposition reactor. The reaction furnace has been heated and maintained at 700. 〇 to 8 〇. 〇 At this time, after the wafer is preheated, ‘after about 60 seconds, the introduction of silicon (Si2H6) gas’ is started, and the pressure of the inlet gas is maintained at 10-5 Torr. That is, the lice body had not penetrated between about 10-8 Torr. The gas flow rate is about 10 seem (standard per cubic centimeter per minute). At the same time, the temperature of the wafer continues to rise to about 600 cC. Finally, as shown in the aforementioned second D diagram, during this process, hemispherical crystals can be grown on the wafer surface, so it is called a hemispherical crystal method.

V. Description of the invention (7) 1-- According to the method described above, the present invention provides a method to increase the etching rate of the silicon oxynitride compound, such as the etching time is less than 300 seconds. And there is no generation of energetic atoms and atomic groups, and it will not penetrate through the surface of silicon atoms. Silicon atoms can migrate to form selective hemispherical crystals. The present invention can not only effectively remove silicon oxynitride compounds, but also silicon nitride-based Thin hard reticle can also be used for private use. And the remaining rate can be specifically increased. It can also improve overall throughput of the fab. —The chemical reaction of wet etching is a reaction between liquid phase and solid phase. When wet money is engraved, 'the reactants of the solution will use the diffusion effect (Diffusion) to pass through a relatively thin boundary layer (BOOundary Layer)' to reach the surface of the silver engraved film "then, these reactants will Produces chemical reactions with molecules on the surface of the film to produce various products. And these products on the surface of the thin film will also use the diffusion effect to pass through the boundary layer into the solution and be eliminated with the solution. At the same time, the wet etching process has no fixed directionality, which is the so-called isotropic #etching. The main parameters of the wet coin reaction are: solution density, contact time, reaction temperature, and solution stirring method. The temperature and humidity etching itself is a kind of chemical reaction ’, so the higher the concentration of the etching solution, or the higher the temperature, the faster the film is removed. Here, the so-called Dry Etching is usually performed by plasma (P1 asma) technology instead of wet film etching technology. Because the etching reaction does not involve a solution, it is called dry etching. The advantage is that it can be anisotropic (An i sot ropy). For dry rice engraving, its selectivity (S e 1 e c t i v i t y) is worse than that of wet touch engraving. Except this

Page 10 424¾. 卞 §

Sentence is also the main basis for measuring the better dry etching, the faster f, which means the larger the output, the better the quality control, the extra-crystal's Eating Rate and the average damage. The surname speed of several neodymium engravings, the higher the uniformity of the etching, the better the yield of the wafer. 〕 Car: Two: Ueto ϋ 2 Ϊ, a kind of RAM with only money engraved in RAM (RAM ^ Feng, in the body, prepare silicon oxynitride (SiON) on amorphous silicon used as a capacitor, and further grow A method of forming a hemispherical crystal, or a method of further preparing a silicon oxynitride (Si0N) on amorphous silicon used as a capacitor in a silver-etched dynamic random memory (DRAM) semiconductor, and then growing into a hemispherical crystal. It can include: a dry etching process; a wet etching process. The advantages of the two processes are combined to carry out the chemical engraving process. The advantage is that the etching rate of the nitrogen oxide silicon compound can be increased and a better result can be generated. The size of the hemispherical crystal. The proposed dry etching method includes a low-energy dry etching method. The other wet etching method includes a thermal phosphoric acid (H3P04) touch engraving method. The application park of the present invention It also contains the description of the fossil of the IL. According to the above, it is only a preferred embodiment of the present invention, and is not intended to limit the scope of the patent application of the present invention; all others can be completed without departing from the spirit disclosed by the present invention. Equivalent change 1 or modifications should be included within the scope of the following patent application of Alex.

Page 11

Claims (1)

4 24279 '' A chemical etching method for removing a hard mask layer in a semiconductor process. The etching method at least includes: /, etching the hard mask with a low-energy dry etching method, so that the thickness of the hard light reaches about less than 1 〇 Angstroms; and 'The remaining thickness of the wet etch is used to completely remove the hard mask, and the wet etch has an etching rate of about. The minute etch method can be used to increase the production of hemispherical crystals in the process. The hard mask with a degree of less than 100 angstroms has a wet etching time of less than 300 seconds and 80 angstroms; the dry etching method and the etching rate of the wet and etched hard masks are beneficial The above-mentioned method includes the following steps: 2. The oxynitride-type hard photomask is engraved according to the method in the first item of the patent application scope. 3-The method according to the first item of the scope of patent application, wherein the above-mentioned low-energy dry tooth / method includes at least a plasma etching method with a high nitrogen oxide silicon compound / silicon dioxide (si0N / Si〇 ^ etch selection ratio. At least one of the above wet I insect engraving methods includes the above-mentioned method 4_ If the method of the scope of patent application No. 1 includes a thermal phosphoric acid (h3po4) etching method. Photomask. Page 12 6. A method of applying for a patent, wherein the etching method includes at least a low-energy dry etching method to etch the silicon nitride oxide into silicon oxide compound to a thickness of less than about 100 angstroms; and Material, so that the nitrogen is etched by the wet etching method of hot phosphoric acid (HsP〇4) :: the oxynitride compound is used to completely remove the oxynitride. : 矣 ′ The dry etching method and the wet etching method can be used to increase the silver etching rate of the silicon oxynitride compound, and then the step of generating hemispherical crystals is continued. 7. The method according to item 6 of the patent application range, wherein the above-mentioned low-energy dry etching J method includes at least a plasma etching method with a high nitrogen oxide silicon compound / silicon dioxide (si 0N / si 02) etching selection ratio. 8. If the method according to item 6 of the patent is requested, the above-mentioned method further includes a silicon etched silicon nitride type hard mask. ,