TW495880B - Method of repairing a low dielectric constant material layer - Google Patents

Abstract

A method of repairing a low dielectric constant (low k) material layer starts with coating a photoresist layer on the low k material layer on a semiconductor wafer. After transferring a pattern of the photoresist layer to the low k material layer, an oxygen plasma ashing process is performed to remove the photoresist layer. Finally, by contacting the low k material layer with a solution of alkyl silane comprising an alkyl group and halo substituent, Si-OH bonds formed in the low k layer during the oxygen plasma ashing process are removed so as to repair damage to the low k material layer caused by the oxygen plasma ashing process, and to enhance a surface of the low k material layer to a hydrophobic surface to prevent moisture adhering to the surface of the low k material layer.

Description

FIELD OF THE INVENTION The present invention provides a method for repairing a low dielectric constant material layer, in particular ^ ^ ^ ^ (alkyl group) a ^ ^ ^ ^ ^ (hal (crushing solution) eliminates the low dielectric constant material layer. Silicon-lice milk (Si-0H) bond to repair the damage caused by the low dielectric constant plasma ashing process. The background of the milk hole shows that the size of semiconductor devices is shrinking and the density of integrated circuits is increasing. Alas, the accompanying jRC delay effect between the metal wires has seriously affected the operation efficiency of the integrated circuit b 'greatly reducing the operating speed of the integrated circuit. Especially when the process line width (line When the width decreases to 0.25 microns, or even below 13 microns, the effect of the delay effect of rC will be more obvious. The privacy of the effect caused by the RC delay effect between the metal interconnects and the resistance of the metal wire Value (r) is proportional to the product of the parasitic capacitance (C) of the dielectric layer between the metal wires, so a metal with a lower resistance value can be used as the metal wire, or the parasitics of the dielectric layer between the metal wires can be reduced. Power Valley ' Reduce the RC delay effect. In terms of reducing resistance, use pure copper as the copper wire technology (Coppeinfer Corning Ct technology) to replace the traditional aluminum-copper alloy (A1: Cu (〇 · 5%)) Mainly

Fifth, the invention explains that the process of the material] resistivity does not cause problems, because the connection layer metal wire-some process electrical layers (2) multiple metals) has become (1. 6 7 "with aluminum copper can reduce this However, the problems caused by the capacitors are due to the dielectric (the lower the dielectric, the traditional constant materials below 0.1 microns are formed, such as FpI, PAE-2, and the like. However, these low dielectric constant No matter whether it is related to various properties or not, most of them have not been properly processed (multilevel metallization is an inevitable trend. Because copper itself has a lower Ω-cm), and can bear a higher The current density and the electro migration of gold, the parasitic capacitance between the metal wires and the metal wires alone cannot be significantly reduced by the copper connection wire technology, and the copper connection wire technology has yet to be resolved. Therefore, the method of reducing the RC delay effect by reducing the dielectric between the metal wires is very important. The parasitic capacitance of the layer is related to the dielectric constant of the dielectric layer, constant, k). The dielectric constant of the layer in the dielectric layer is relatively lower. The dielectric constant of Shi Xi is 3.9, which has gradually failed to meet the requirements of the current semiconductor process. Materials such as polyimide (PI), FLARETM, PAE-3, or LOSP have been gradually lowered in recent years. Although f-number materials have a range between 2 · 6 ~ 3 · 2 ' However, the adhesion, etching effect, or other characteristics of these low-k dielectric materials, which are generally composed of hydrocarbons, are significantly different from traditional silicon dioxide, and they have poor adhesion and insufficient thermal stability. And other shortcomings, so it is purposely integrated into the common IC process.

495880 V. Description of the invention (3) — So 'some low dielectric constant dielectric layers based on monoxide and then some hydrocarbons and other elements, such as HSQ with a dielectric constant of 2 8 (hydrogen silsesquioxane), elbow 5 卩 with a dielectric constant of 27 (11161: 1 ^ 131136391 ^ 〇 and 3116), HOSP (hybrid-organic-si 1〇χane-polymer) with a dielectric constant of 2.5, and porous Porous sol-gel and other materials, because of their properties are not far away from the traditional stone dioxide, so they have a high integration ability to the currently known semiconductor process, and are optimistic in the future. " "-Please refer to Figure 1 to Figure 3. Figure 1 to Figure 3 are schematic diagrams of conventional methods for removing photoresist. As shown in FIG. 1, the surface of a semiconductor wafer 10 includes a silicon-based substrate 12 and a chemical vapor deposition method (chemica 1 va ρ οr deposition (CVD) or spin-on). It is formed on the surface of Shi Xi substrate I ?, and is made of materials with low dielectric constant, such as HSQ, MSQ, HOSP, or porous gel, with silicon dioxide as the basic structure (S i 0 2 -based) 14. As shown in FIG. 2, a photoresist layer 16 is first coated on the low dielectric constant material layer 14, and a pattern opening 18 is formed in the photoresist layer 16 to expose a portion of the low dielectric constant. Constant material layer 1 4. Then, the low-constant material layer 14 is dry-etched through the pattern opening 丨 8 to transfer the pattern in the photoresist layer 16 to the low-dielectric constant material layer 14. After that, as shown in Figure 3, a photoresist removal process is performed, and an oxygen gas is first used.

495880

V. Description of the invention (4) Plasma ashing the photoresist layer 16 to completely react the oxygen plasma with the carbon and hydrogen elements in the photoresist layer 16 to form gaseous carbon dioxide and water vapor. Finally, the semiconductor wafer 10 is immersed (d i pp i ng) in a photoresist removal solution to completely remove the photoresist layer 16. However, the transfer of the dioxide pattern will affect the dry oxygen, so after removing Si-〇HI, it will poison the reliability. In the future, the use of water-resistance alkaline gas water will be possible

When transferring dielectrics made of low-dielectric constant materials such as HSQ, MSQ, Η 0 SP, or porous gels as the basic structure, no matter whether the dielectric layer is #etched or the photoresist removal process is performed, Electrical layers cause injury. Because the photoresist removal process usually involves simultaneous electropolymerization ashing process and wet photoresist removal to remove the bond on the surface of the dielectric layer, it is easy to be broken by the oxygen plasma, and the disc resistance liquid reacts, causing damage. The surface of the dielectric layer is easy to absorb-because the dielectric constant of water is as high as 78, the dielectric constant and leakage current of the adsorption: layer will increase significantly, even in the case of a poison via, which seriously affects the product invention Summary Therefore, the main purpose of the present invention is to provide a layer method to solve the above-mentioned conventional reasons. ≫ Set the dielectric constant and leakage current of a low dielectric constant material to increase significantly. The 'medium' low dielectric constant dielectric layer is A semiconductor in a preferred embodiment of the present invention

B contains one

V. Description of the invention (5) The low dielectric constant processing step of the silicon monoxide structure is performed by opening the constant material layer to expose the exit dry etching the low-moving to the low-dielectric range to remove the sulfonium-substituted substrate. The dielectric constant material damages the low-dielectric and low-dielectric-constant materials, and at the same time the (hydrophobic with 0 part of the dielectric is often a photo-resistive layer (halo layer, with several layers of material on the low-dielectric layer :) surface (SiOrbased) low dielectric constant material layer. First, a hydrogen plasma (hydrogen plasffla) 2 $ xuan low dielectric constant material layer is performed on the material layer. A photo-resistive layer is formed with a low-electricity, low-electricity material layer. The material is then passed through the photo-resistive layer to transfer the pattern in the photo-resistive layer. Finally, an oxygen plasma ashing is performed. Reliability: contacting a silane solution containing an alkyl group (^ bstituent) to the low elimination silicon-hydrogen (Si-OH) bond existing in the layer due to the oxygen plasma ashing process, And repair the surface change of the loss constant material layer in the oxygen plasma ashing process Hydrophobicity prevents the absorption of moisture in the environment. The manufacturing method of the present invention exists in the ashing process of a calcined solution containing an alkyl uik in contact with the low dielectric constant ^; The oxygen electro-polymerization (CD-0H) bond, so that the ^^ Λ constant into the material / in the stone Xi-Hydroxy Plasma ashing process is damaged v is: η number of material layers in the oxygen method can be simultaneously This low dielectric, the producer of the present invention prevents the surface of the water vapor layer in the environment from changing to a hydrophobic surface and attached, so it can completely solve the conventional manufacturing process 495880 5. Description of the invention (6) leads to a low dielectric constant The dielectric constant and leakage current of the dielectric layer are greatly increased. Detailed description of the invention Please refer to FIGS. 4 to 7. FIGS. 4 to 7 are schematic diagrams of a method for repairing a low dielectric constant material layer according to the present invention. As shown in FIG. 4, a semiconductor wafer 40 includes a stone substrate 4 2, and a silicon substrate 4 2 is formed by a chemical vapor deposition method (chemica 1 vapor deposition (CVD) or spin-on method). The surface is composed of HS Q (hydr og ensi 1 sesqui ox ane), MSQ edge (methyl silsesquioxane) -HOSP (hybrid-organic-si loxane-p〇lymer), or porous sol-gel, etc. The silicon dioxide is a low-dielectric-constant material layer 44 composed of a SiO2-based material. As shown in Fig. 5, first a temperature of 200 to 350 ° C and a pressure of 200 to 350 millitorr (mT or r) are used, with a flow rate of 200 to 350 Standard cubic centimeters per minute (sccm) of hydrogen gas and a hydrogen-containing plasma (hydrogen plasma) formed by radio power of 90 to i50 watts (Watts), a hydrogen-containing plasma treatment step ( hydrogen-containing plasma treatment) to strengthen the low dielectric constant material layer 44. Then, a photoresist layer 46 is coated on the low dielectric constant material layer 44, and a pattern opening 48 is formed in the photoresist layer 46 to expose a part of the low dielectric constant material layer 44. Subsequently

Page 10 495880 Five as the invention description (7) 44 Figure Yang = case opening 48 dry contact etched low dielectric constant material layer to transfer the pattern in the first resistive layer 46 to the low dielectric constant material layer 0 h Ϊ f # ， Proceed—Removing the photoresist process, first use—oxygen polymerizing first resist layer 46, so that the oxygen plasma and carbon in photoresist layer 46 react to form gaseous carbon dioxide. ^ ^ ^ ^ ^ „R, (w: t strtpperH t Ϊ θ 0θ3 " 4〇 ^ In order to remove the remaining residue on the surface of the low-level two-layer material layer 44 Photoresist layer 46. At this time, the photoresist liquid will damage the low-dielectric-constant material ^ ^ The material layer 44 generates Si-0Η bonds and absorbs ^ low, the dielectric lightning H p ^ & e The low dielectric constant material layer increases the number of mills and the problem of leakage current. After that, the low dielectric constant material layer 44 is subjected to a surface treatment), that is, the semiconductor wafer 40 is immersed in an alkyl group and a halogen substituent. (&Quot; (alkyl towel, or = Ul bt ^ 1) the silane solution on behalf of a certain Weng production p from the film 40 is placed in a full of the alkyl-containing and halogen taken The base C gas is bad. Usually the alkyl-containing solution is a volume percentage with a concentration less than = trimethylChlorosilane (TMCS) / Hexane = Shixi burning will have low dielectric The surface of the constant material layer 44 is reversed, and the two-oxygen plasma ashing process exists in the low dielectric. Because of the Si-OHM 〇! ≪ The reaction formula is shown in Figure 8. si-0 形成 can form 8b 08 丨 ((: 113) 3 after / 5 library, and you pass this; 5_ 止 〇Η 于 in reaction ^ 3 and I pass After this chemical reaction step, TMC%

V. Description of the invention (8) Si in the constant material layer 44 is bonded to repair the low dielectric # & Φ 2: 4 The damage suffered in the photoresist removal process is more, low, The original hydrophilic surface of the number material layer 44 was changed to a hydrophobic iy iophobi_c) surface to prevent the moisture absorption in the subsequent process environment. Κ = followed by a hot baking at 4 0 C and a holding temperature of 30 minutes (h 0). ta ing) to remove TMCS remaining on the low dielectric constant surface.

In another embodiment of the present invention, TMCS may be replaced with other mono-halo substituents such as trimethylchlorosilane (Si (CH3) 3Cl), dimethyl chloride Dimethylchlorosilane (Si (CH3) 2HCl), ethylchlorosilane (Si (C2H5) H2Cl), propylchlorosilane (Si (C3H7) H2Cl), monoethyl 〆bromide silane (ethylbromosilane, Si (C2H5) H2Br), monopropyl-bromo sulfide (port 1′〇 口 乂 11) 1′〇111〇3113116,81 ((: 3117) 11231〇, etc. It can also be composed of the combination of the above substances. Please refer to Figure 9, which is the infrared spectroscopy of the porous gel dielectric layer. As shown in Figure 9, the curves A and B represent the porous gel dielectric, respectively. The infrared spectrum of the layer before and after the oxygen plasma photoresist removal process, and the curve C is the infrared spectrum obtained by the porous gel dielectric layer after the oxygen plasma photoresist removal process and TMCS treatment. Among them, Absorption peak 1 represents the absorption peak of the Si-0H bond, and its absorption position is located at 3 0 0 0 to

Page 12 495880 V. Description of the invention (9) Within the wavelength range of 3500cm-. As shown in FIG. 9, after the porous gel dielectric layer undergoes an oxygen plasma photoresist removal process, the absorption peak 1 of the Si -OH bond is obviously generated, and the porous gel dielectric layer after TMCS treatment, The intensity of the Si-OH absorption peak 1 decreases accordingly. Please refer to Figure 10, which is a bar graph of the dielectric constant of the porous gel dielectric layer. As shown in Figure 10, the dotted squares A and oblique squares B respectively represent the dielectric constants of the porous gel dielectric layer before and after the oxygen plasma photoresist removal process, and the latticed square C represents the porous gel. The dielectric constant of the dielectric layer after the oxygen plasma photoresist removal process and TMCS treatment. As shown in Figure 10, after the porous gel dielectric layer undergoes an oxygen plasma photoresist removal process, the dielectric constant is increased from 1.9 to 3.8; however, after the TMCS treatment, the porous gel The dielectric constant of the dielectric layer dropped back to 2.7, showing that TMCS can repair the damaged structure of the porous gel dielectric layer and improve the problem of increased dielectric constant. Please refer to Fig. 11, which is a graph showing the relationship between the electric field and the leakage current density of the porous gel dielectric layer. As shown in Figure 11, the circle symbol • and square symbol represent the relationship between the electric field and leakage current density of the porous gel dielectric layer before and after the oxygen plasma photoresist removal process, and the triangle symbol ▲ represents porous The relation curve between the electric field and the leakage current density of the gel dielectric layer after the oxygen plasma photoresist removal process and TMCS treatment. As shown in Figure Η—the leakage current density of the porous gel dielectric layer before the oxygen plasma photoresist removal process is very low, about 10-1 to 10_9A / cm2. After the blocking process, the leakage current density increases significantly by 3 to 4 orders. however

Page 13 495880

V. Description of the Invention (ίο) The leakage current density can reduce the damage of the gel dielectric layer. After TMCS treatment, the porous gel dielectric layer has about 1 to 2 orders, showing that TMCS can repair the porous structure. , And improve the problem of increased leakage current. Compared with the conventional technology, the present invention uses a semiconducting = s / hexane solution to make TMCS and a low dielectric constant material ^ layer ^ bubble surface on the surface-and eliminates the ashing process due to the oxygen plasma The Si-OH bond existing in the low-dielectric J material layer 44 achieves the purpose of repairing the damage of the low-dielectric-constant material layer 4 = ^ the oxygen plasma ashing process, so that the original dielectric 1 is restored. In addition, the TMCS / hexane solution can make the low-dielectric constant symbol and the original hydrophilic surface of layer 44 change to hydrophobic (hydropaph VIII) to prevent the adsorption of water vapor in the subsequent process environment, thereby solving the conventional problem. The problem that both the dielectric constant and the leakage current of the constant dielectric layer are greatly increased: to avoid the deterioration of the dielectric characteristics of the "constant material layer 44." Note: Only the preferred embodiments of the present invention are described, where Application of the patent application in accordance with the present invention ^ Equivalent changes and modifications 1 should belong to the scope of the invention patent

Page 14 495880 Simple description of the diagrams Simple explanation of the diagrams Figures 1-3 are schematic diagrams of conventional methods for removing photoresist. Figures 4 to 7 are schematic views of a method for repairing a low dielectric constant material layer according to the present invention. Figure 8 shows the chemical reaction formula between TMCS and the dielectric layer. Figure 9 shows the infrared spectrum of a porous gel dielectric layer. Figure 10 is a bar graph of the dielectric constant of the porous gel dielectric layer. Figure Η——is the relationship between the electric field and the leakage current density of the porous gel dielectric layer. Symbol description

10 semiconductor wafer 12 silicon substrate 14 low dielectric constant material layer 16 photoresist layer 18 pattern opening α 40 semiconductor wafer 42 silicon substrate 44 low dielectric constant material layer 46 photoresist layer 48 pattern opening V

Page 15

Claims (1)

495880 Sixth, the scope of patent application The material layer is composed of one of the following materials: HSQ (hydr〇gefl silsesquioxane), MSQ (methyl si lsesquioxane), HOSP (hybrid-organic-si loxane-polymer), or porous so 1- ge1〇4: The method of applying for the scope of patent application No. 1 applies a photoresist layer on the low-dielectric constant material and further includes a hydrogen electric destruction (hydrogen pia processing step 'for strengthening the low-dielectric constant). Material layer: a) 5. The method according to item 1 of the patent application, wherein the silane-based solution containing an alkyl group and a prime substituent is a hexane solution. % 6 · The method according to item 5 of the scope of patent application, wherein the silanes containing an alkyl group and a prime substituent are a mono-halo-based sintered silicon. 7. The method according to item 6 of the scope of patent application, wherein the silanes containing a burning group and a dentin substituent are composed of one of the following components or combinations: Trimethylchlorosilane (Si (CH3 ) 3Cl), dimethylchlorosilane (Si (CH3) 2HCl), ethylchlorosilane (Si (C2H5) H2Cl), and propylchlorosilane (Si (Si (C2H5) H2Cl)) C3H7) H2Cl), ethylbromosilane (Si (C2H5) H2Br), and propylbromosi lane (Si (C3H7) H2Br). Page 17 495880 VI. Application for patent scope 8 · = Method for applying for patent scope item 1, wherein the alkyl-based silane-based silane solution is a trimethylchlorosilane (trimethylchlorosilane, TMCS) hexane solution. A step layer; a method for repairing a low-dielectric-constant material layer, the method comprising a lower body wafer including a low-dielectric-constant material provided to provide half of the low-dielectric-constant material layer ; Through a pattern in the patterned photoresist layer using a photoresist for at least one gr0up) and halogen contacting the low dielectric constant wherein the alkane-containing = the photoresist ashing to produce hydrogen (Si-0H) bonding process The surface of the substrate is changed to a photoresist layer on the sparse material layer; an opening is formed in the middle to expose a part of the low dielectric opening, dry etch the low dielectric constant material layer, and transfer to the low dielectric constant material layer. In the dielectric constant material layer: ^ ashing process to remove the photoresist layer; and sub-surface repair process, using an alkyl-containing substituent (halo SUbstitlJf ^ ten) visit the 1 kyl number material layer; ltuent) The silane-based materials of the Shixian-based material group and the i-substituent may exist in the low-dielectric-constant material layer ^^ and repair the damage of the low-dielectric-constant material layer at n-, and at the same time may The low first resistance ash water (hy dropho b i c) surface_. Material layer 495880 6 'Application for patent scope 10 · The method of the 9th scope of the patent application, wherein the low dielectric constant material layer is composed of one of the following materials: HSQ (hydrogen silsesquioxane), MSQ (methyl silsesquioxane), H. sp (hybrid-organic-si loxane-polymer), or so 1-ge 1 〇1 1 · The method according to item 9 of the patent application, wherein the photoresist ashing process is performed using an oxygen plasma . 1 2 · The method according to item 9 of the scope of patent application, wherein the photoresist ashing process is performed using an ozone-containing plasma. 13. According to the method of claim 9 in the scope of patent application, before the photoresist layer is coated on the low dielectric constant material layer, a hydrogen plasma (hydrogen pUsma) processing step is further included to strengthen the low dielectric constant material. Floor. 14. The method according to item 9 of the scope of patent application, wherein the stone-fired substance containing an alkyl group and a halide substituent is dissolved in a hexane solvent. 15. The method according to item 14 of the patent application, wherein the alkyl-containing and halogen-based silane-based solution is a trimethylchlorosilane (TMCS) hexane having a concentration of less than 8% by volume. Solution 16. The method according to item 9 of the patent application, wherein the alkyl group and halogen 495880 VI. Scope of patent application Silanic substances with a substituent of a prime group are pure silanes containing alkyl groups and radicals. 17 · The method according to item 9 of the scope of patent application, wherein the silane-based substance containing an alkyl group and a halogen substituent is a silane with a single halogen substituent. 18 · The method according to item 17 in the scope of patent application, wherein the silanes containing alkyl groups and halogen substituents are composed of one of the following components or combinations: trimethylchlorosilane, Si (CH3 ) 3Cl), dimethylchlorosilane (Si (CH3) 2HCl), ethylchlorosilane (Si (C2H5) H2Cl), propylchlorosilane, Si (C3H7) H2Cl), ethyl ethyl bromosilane (Si (C2H5) H2Br), monopropyl bromolith (Si (C3H7) H2Br). Page 20