TW471108B - Preparation of ultra low dielectric constant silicon dioxide film with nanometer pores - Google Patents

Abstract

This invention provides the preparation of ultra low dielectric constant silicon dioxide film with nanometer pores. Firstly, a silicon dioxide precursor solution is prepared, in which there are at least a template polymer and a modifier. The precursor solution is spun coated on a silicon substrate and then a calcinations process is carried out to remove the template polymer and form a plural number of regularly aligned nanometer pores. The preliminarily prepared low dielectric constant nanometer pored silicon dioxide film has a dielectric constant of 2.50. The film is further treated by hydrogen and HMDS modifier vapor to modify pore surface, which leads to a reduced dielectric constant of 1.42-2.0 for the nanometer pored silicon dioxide film.

Description

471108 V. Description of the invention (1) About 2 Preparation of a nanometer hole thin film material, especially n nanometer hole dioxide dioxide film with ultra-low dielectric constant in the process of using 'low dielectric constant α value) The thin film material can be made in layers to solve the problems of miniaturized integrated circuits, such as group V, eight links, signal interference, and power loss. Yi Lei, bismuth = I7 cheeks, η roughly differentiates low dielectric constant thin film materials into organic dielectric stable—2 ϊ inorganic dielectric materials, of which organic dielectric materials have lower heat ^^ # and poor material compatibility , Gas dissipation, and dielectric stability, etc. ^ Coarse = inorganic silicon dioxide dielectric materials have better thermal stability. Di-granular can be reduced if the holes are introduced into the film, which can reduce its dielectric constant. The electric pair V / can be reduced to k < 2 · 0. At present, the most representative inorganic encapsulation material is porous silicon dioxide film. Xu Erlu, the preparation method of silicon dioxide film with holes can be summarized as three. (1) aerogel / xerogel method; (2) in: rolling silicon coating solution Add organics to form microfoam, and then use the calcination process to remove organics to form pores; (3) Second force in the silicon dioxide coating solution: two-phase Umohiphilic molecules, used as template: Then the template molecules will self-structure Uelf-asseinbly during the coating process to form a specific phase 'and then cause a regular structural component f'. After the template molecules are removed by the calcination process, regular = holes can be formed. For the (1) aerogel / xerogel method, although it can meet the requirements of hole density and ultra-low dielectric constant (k = 13-25), there are problems of shrinkage and residual stress during heat treatment. So its holes are large

471108

Small unevenness, poor mechanical properties, less practical application. For the (2) microbubble method, although uniform pore size can be prepared, the distribution of pores / ~ is irregular, which will affect the pore silicon dioxide film = mechanical and electrical properties. As for the self-structuring method of the rhenium template molecule, its pore density can reach 4 5-75%, the pore size is consistent, and the pores are regularly arranged in jade. Therefore, it is generally believed that this method can be produced with relatively == mechanical and electrical properties. Hole in silicon dioxide film. The conventional self-structuring technology using template molecules mostly adopts the dip-coating method. The silicon dioxide coating solution will be applied to the upper and lower surfaces of the wafer at the same time, which requires additional work. Single-side cleaning process, so its process efficiency is low and it is not compatible with existing semiconductor processes. In order to solve the above-mentioned shortcomings such as low process efficiency and incompatible process, the conventional technology also uses a spin-coating process instead of the dip coating method, but its holes cannot be arranged regularly, which will affect the Dielectric constant value and mechanical properties of porous silicon dioxide film. Moreover, it is known from the literature that its dielectric constant can only be as low as k = 1,8 ~ 2 · 2, and its mechanical properties may not meet the requirements of chemical mechanical polish (CMP) process and metal damascene process. . In addition, the surface of the porous silicon dioxide film has many Si-OH bonds, and its water absorption property often causes the dielectric constant to increase significantly. Therefore, in order to control the stability of the dielectric constant, the porous silicon dioxide film must also be formed. The surface is converted into hydrophobicity to meet the needs of practical applications. In view of this, the object of the present invention is to propose a method for preparing a silicon dioxide film with ultra-low dielectric constant nanometer holes, which can be fabricated with

0522-5668TWF * ptti Page 6 471108 V. Description of the invention (3) ^ Porous silicon dioxide film with low dielectric constant (k = 1.42 ~ 2.0), high thermal stability, pole two, and stable electrical properties, and is in line with traditional : p Compatible to solve the problem of Xi's technology. ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, l ,,,,,,,,,,,,,,,,,,,,,,,,, &, The solution contains at least one template) high score: and -TMCS modifier, and then coated with a spin coating precursor solution on a stone substrate. I was stunned and advanced into defense-forging; the calcination process removes the template polymer to form several shells; the nanometers are pores, and they are preliminarily produced with low dielectric constant (jk- 2.50). Find microporous silicon dioxide film. Further treatment with hydrogen and steam treatment with HMDS modifier on the surface of the pores can produce ultra-low dielectric constant How micron pores of silicon dioxide 1 can be reduced to k = l 42 ~ 2. 0 〇 八 ， 丨 私· Simplified illustration of books and figures In order to make the above-mentioned objects, features, and advantages of the present invention more obvious and easy: Yueru; Wen special mentions a preferred embodiment, and in conjunction with the accompanying drawings, the first picture is described A flowchart showing the process of the present invention is shown. Figure 2 shows the diffraction pattern of the holed silica film during calcination. 1 W H U Λ% Figure 3 shows the infrared absorption spectrum of a porous silicon dioxide film during the calcination process. β

471108 V. Description of the invention (4) Figure 4 shows the pores and holes of the present invention; the change in the series of modification steps of the film "& "Earth dioxide film of pores No. 8" > Time change diagram. The electrical constants are prepared with [symbol description] an acid-catalyzed stone dioxide sol gel ~ 1 Q; Timlikou ~ 12; aging treatment ~ 14; TMCS modifier ~ 16 added; ^ two-phase high-range ~ 18; Baking process ~ 20; Calcination process ~ 22; First ^^ coating system ~ 24; HMDS modifier steam treatment ~ 26; Second hydrogen gas treatment A gas treatment ^ Description of preferred embodiments: The present invention proposes A nano-siliconized thin film process with ultra-low dielectric constant, which is spin-coated at Yilidong 2nd day f * 7r | Precursor 〇r In the solution, template molecules in the silicon precursor solution added and coated are used to self-organize and distribute the structure, and then the template molecules are removed by the calcination process to form regular holes. In addition, the method of the present invention modifies the surface of the holes ^ ^ nanometers, so that the hole silicon dioxide film has excellent thermal stability and] =, but can also further reduce its dielectric constant to 丨. 42 ~ ^ 〇. μ < 凊 Refer to FIG. 1, which is a flowchart showing the process of the present invention. First, a monoxide precursor solution is prepared. Step 1 Q: A single-step synthesis of an acid-catalyzed silica sol-gels (sol-gels). The method is to use 70 ° C, A degree, 90 minutes, and

Page 8 471108 V. Description of the invention (5) The mixed solution of TEOS (tetraethyl ortho silica te), H20, HC1 and ethanol is refluxed (ref lux). Step 12: Adding a two-phase polymer (tr ibk copolymer PI ur on ic, PI 23) as a template molecule to the acid-catalyzed silica dioxide sol gel to prepare a silicon dioxide precursor solution The molar ratios of the various reactants are TEOS: P123: H20: HC1: ethanol =; [: 〇.〇〇8 ～ 〇 · 〇3: 3.5 ~ 5: 0.003 ~ 0.03: 10 ~ 34. Step 14: The silicon dioxide precursor solution is aged for 3-6 hours at room temperature and in the same environment (ιη-situ). Step 16: Mix the TMCS (trimethylchlorosilane) modifier into the silica precursor solution by vigorous stirring, wherein the molar ratio of the TMCS modifier to τEOS is 0.02 to 0.2. Next, step 18: apply the silicon dioxide precursor solution to the spin coating method under the same environment at a speed of 1 600 rpm, an acceleration of 1600 rpm / ^ 0, and a time of 30 seconds. On the surface of a silicon wafer. Then, the silicon wafer is subjected to a baking process at step 20 · 疋, the temperature is 80 ° C to 315 ° C, and the time is 3 hours. Followed by # 22: a Shixi wafer is subjected to a forging process in a gas flow furnace tube. The temperature is 40 ° C, and the time is 30 minutes. Because the template molecules will self-structure during the coating process to form The specific phase and each have a regular structure distribution, so the template molecules can be removed after the calcination process to form a regular distribution of holes, so that the pore dioxide dioxide film of the present invention has been initially completed. I verified through experiments, According to the results of the adsorption and desorption isotherms of radon gas, the porosity of the silicon dioxide film of Ben Zhi's pores can reach 53% and the pores can reach 53%.

471108 V. Description of the invention (6) The diameter of the hole is 43-80A. Moreover, the microstructure of the pores can be observed by using the light diffraction (xrd) diagram and the transmission electron microscope (TEM) picture shown in FIG. 2 to verify that the method of the present invention can indeed be used after the calcination process. Holes having a nanometer size (3 to 9 nm) and a regular structure are formed in the silicon dioxide film. In addition, by using a metal-insulator-semiconductor (MIS) capacitor and structure, the dielectric constant of the hole-shaped silicon dioxide film of the present invention can be measured, which is about k-2 · 5, compared with that applied to In terms of the requirements (k < 3) of the dielectric materials of the ULSI process, it is shown that the method of the present invention is consistent with practical application. Regarding the formation mechanism of regularly distributed pores, under the condition of acidic hydrolysis with low water content, the condensed silica sol has more linear configuration and less dendritic configuration, so it is undergoing aging treatment. Afterwards, the unreacted suanol groups located on the line-shaped silica sol can further produce condensation or modification. When TMcs modified clams are added to the aging-treated silica sol, the modifier will quickly react with the silanol group to provide the required hydrophobicity. Subsequent to the second: after the sol and template molecules are mixed to form a silicon dioxide precursor solution, there is a weak force, mouth, van der Waals force, dipole-dipole interaction between the silica dioxide sol and the template molecules. (Force) and the binary structure of the template molecule, the force is the main driving force for the formation of the hole structure. As shown in Figure 3 and below, the red evening line absorption spectrum (1R) shows that using TMCS modified film 'before the calcination process, the template molecules in the film; after the calcination process, the film and the male The molecules of the machine plate have been removed, so the IR picture is completely absent.

471108 V. Description of the invention (7) There is an absorption signal of s 1 -OH. Only the functional absorption signal left by the modifier after the modification. In addition to this, 'In order to passivate dangling bonds and residual traps, it is necessary to carry out progressive modification of the porous silicon dioxide film' to reduce its hydrophilicity and dielectric constant. . The following is a detailed description of the modification process of the hole surface, and Figure 4 shows the change of the dielectric constant in a series of modification processes. Step 24 •• During the hydrogen treatment of the younger brother, the temperature of 250 ° C and the time of 30 minutes can reduce the dielectric constant value of the holed dioxide film from k = 2 · 5 to k = 2 · 23 At the same time, the carbon content in the film is reduced. Next, step 26 •• is subjected to a HMDS (= exame thydi slazane) modifier steam treatment at a temperature of 150 ° C and a time of 60 minutes', so as to further reduce the dielectric constant value of the porous dioxide film. To k =! · 53. Finally, the second hydrogen treatment in step 28 •• can further increase the dielectric constant of the porous silicon dioxide film to k = 1.42. Please refer to the change of the dielectric constant with time shown in Figure 5. When the nano-silicon dioxide film with ultra-low dielectric constant is invented, its dielectric constant value will be only slightly within 22 days. The amplitude increased by 7% (from the buoy, rose to k = 1.52), which shows that the hole dichlorite film produced by the method of the present invention has excellent dielectric stability ... Bu, through measurement; The hole dioxide produced by the method of the present invention is 50 MPa, and has good adhesion to the silicon film. Compared with the conventional technology, the method of the present invention is applied to the modifier, and hydrogen and gallbladder vapor are used in the subsequent process.

471108 V. Description of the invention (8) The hole size and regularity of the prepared hole are 0), and it has dielectric stability. The coating method is efficient and can also be used for thin film processes. Although the present invention is limited to the present invention, within the scope of God, when viewed as attached, the silicon dioxide film has a porosity of 53-7 2%, nano-structured holes, and an ultra-low dielectric constant of 42 ~ 2. Good mechanical strength, thermal stability, material compatibility, In addition, the method of the present invention replaces the conventional six cloth with a spin coating method, but can make holes with a regular distribution, improve the process valley to the traditional process, so it can be applied in the present Semiconductor Ming has been more familiar with this example, but it is not intended to be used as a more private artisan 'without departing from the spirit of the present invention, please patent patent 0' so the scope of the present invention The definition defined by the standard shall prevail.

Claims (1)

471108 Six 'patent application scope Silicon oxide thin film1. A process for nanometer holes with ultra-low dielectric constant, including the following steps: (a) providing a silicon substrate; (b) preparing a silicon dioxide precursor solution The silicon dioxide pre-solution contains at least a tempiate polymer and a quality agent; and knife-and-TMCS modified (c) coating the silicon dioxide precursor solution on the stone eve by spin coating. On the substrate; and (d) performing a calcination (ca ici nat) process, removing the template polymer to form a plurality of nanometer holes, so as to complete the 氅 micron hole with ultra-low dielectric constant. Oxidized stone eve film. 2. The process as described in item 1 of the scope of the patent application, wherein the dielectric constant of the nano-hole-hole fluorinated shatter film is 2 · 0 ~ 1 · 4. 3. The process according to item 1 of the scope of patent application, wherein the plurality of micron holes are regularly distributed. 4. The process according to item 1 of the scope of patent application, wherein the size of each nanometer hole is 3 to 9 nm. 5. The process as described in item i of the scope of patent application, wherein step (b) the method for preparing the silica precursor solution includes ... (M) a single step synthesis of an acid-catalyzed silica sol gel (sol-gels); (b 2) adding the template rhenium molecule (b3) to the sol-gel for ageing treatment; and (b4) adding a TMCS modifier to the sol-gel. 0522-5668TWF-ptd Page 13 471108 6. Scope of Patent Application 6. The process described in item 1 of the scope of patent application, wherein before performing step (d), a drying and baking process is performed. 7. The process according to item 1 of the scope of patent application, wherein the process further includes step (e): performing a steam treatment process on the ultra-low dielectric constant nanometer hole silicon dioxide film, which can further reduce the ultra-low dielectric constant. The dielectric constant of a low dielectric constant nanometer hole silicon dioxide film. 8. The process according to item 7 of the scope of patent application, wherein the steam treatment process includes at least a second hydrogen treatment process. 9. The process according to item 7 of the scope of patent application, wherein the steam treatment process includes a HMDS modifier steam treatment process. 0522-5668T Wild_pid Page 14