TW200808992A - Copper(I) complexes and processes for deposition of copper films by atomic layer deposition - Google Patents

Abstract

The present invention relates to novel 1,3-diimine copper complexes and the use of 1,3-diimine copper complexes for the deposition of copper on substrates or in or on porous solids in an Atomic Layer Deposition process.

Description

200808992 IX. DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to novel 1,3-diimine copper complexes. The invention is also directed to a method of forming a copper deposit on a substrate or on a porous solid or in a porous solid using a 1,3-diimine copper complex. [Prior Art] by M. Ritala and M. Leskela in Handbook of Thin Film

Materials, H. S. Nalwa? Editor, Academic Press, San Diego, 2001, Vol. 1, Chapter 2, "Atomic Layer Deposition,", The Atomic Layer Deposition (ALD) method is suitable for producing thin films. These films, especially metal and metal oxide films, are key components in the manufacture of electronic circuits and devices. In the ALD method for depositing a copper film, a steel precursor and a reducing agent are alternately introduced into the reaction chamber. After the copper precursor is introduced into the reaction chamber and allowed to adsorb onto the substrate, excess (unadsorbed) precursor vapor is withdrawn or removed from the chamber. The excess precursor vapor is removed followed by a reducing agent which reacts with the copper precursor on the surface of the substrate to form a free form of copper metal and a ligand. This cycle can be repeated if it is desired to achieve the desired film thickness. This ALD method is different from chemical gas phase deposition (CVD) in the decomposition chemistry of metal complexes. In the CVD method, the complex is subjected to pyrolysis upon contact with the surface to produce a desired film. In the ALD method, the complex does not completely decompose into metal upon contact with the surface. Conversely, the formation of the metal film occurs when a second reagent that reacts with the deposited metal complex is introduced. In the preparation of a copper film from a copper (1) complex, the second reagent is a reducing agent. The advantages of the ALD method 113577.doc 200808992 include this ability to control film thickness and the improved coverage area conformability due to the self-limiting adsorption of the precursor to the substrate surface in the first step of the process. In terms of decomposition, it is desirable that the ligands used in the ALD process are stable, and the ligands should be capable of being released from the complex in a metal-free form. After copper reduction, the ligand is released and must be removed from the surface to prevent its incorporation into the metal layer being formed.

The film. [Summary of the Invention]

The method comprises: a method of forming a copper misalignment on the substrate; contacting the substrate with the copper complex (I), deposits of the object;

The deposited composition and the reduced L system are selected from the group consisting of C2-C; the C2-Cl5 smoulder is selected, and the contact agent is not contacted, wherein the C2_C15 alkyne, the nitrile, the aromatic aromatic heterocycle And phosphine 113577.doc 200808992 η is 1 or 2; R and R are independently selected from Cl, which is substituted by H, CrC# alkyl, or fluorine. Alkyl and SUR, a group of constituents, wherein each R4 is independently alkyl; R is independently selected from the group consisting of a C1-C4 alkyl group, a fluorine-substituted C-g-q-alkyl group, and Si(R4)3, wherein R4 is independently The ground is an alkyl group; and the reducing agent is selected from the group consisting of 9_bbn (9-boron bicyclic (3.3.1) smoldering), diboron burning; brxH3-xB type boron burning wherein x=〇, 1 Or 2 and R is independently selected from the group consisting of phenyl and ci-Ci 〇 alkyl; dihydrophenyl hydrazine; pyrazolidine, a diarrhea 'SiR'yH4-y form of Shi Xi burning where y = 〇, 1, 2 Or 3 and R, independently selected from phenyl and Ci-Ciq alkyl; and z-form decane wherein z = 0, 1, 2 or 3 and R, independently selected from phenyl and Ci-Ci decyl. Another aspect of the invention is an article comprising a copper diimide complex (I) deposited on a substrate. Another aspect of the invention is a composition corresponding to the copper complex (j). Another aspect of the invention is a composition corresponding to the ligand (I]t), R1\ R2 Hh]/

Wherein η is 1 or 2; R1 and R2 are independently selected from the group consisting of hydrazine, CrC4 alkyl, fluoro-substituted cc 113577.doc 200808992 alkyl and Si(R4)3, wherein each R4 is independently CkG alkyl And R3 is independently selected from the group consisting of an alkyl group, a fluorine-substituted c!-C4 alkyl group, and Si(R4)3, wherein each R4 is independently a Cl_c4 alkyl group. [Embodiment] Applicants have discovered an atomic layer deposition (ALD) method suitable for producing a copper film. These copper films can be used as seed layers in the copper interconnect formation process of integrated circuits or can be used in a variety of decorative or catalytic applications. The copper (1) complex used in this method is volatile at 35 〇 T 〇 rr at a temperature of about 50 to 12 ° C, and is hot at 50 to 150 ° C at 350 mT Torr to 1 Torr. Stable and derived from a ligand containing C, hydrazine and N but not limited to these elements. The ligand is selected to form a copper (1) complex which is volatile over the temperature range but does not decompose into copper metal within this range of service. Instead, the complexes decompose into metals upon addition of a suitable reducing agent. In addition, the soil k is selected and after the steel complex is exposed to the reducing agent, the ligands will be released without decomposition. It has been shown that at moderate temperatures, the reduction of the copper complex to a copper metal by a commercially available reducing agent can be carried out completely. In the method of the present invention, the steel is deposited on the substrate by the following method: 1. The substrate is in contact with the copper complex (1) to form a deposit of steel on the substrate, and 113577.doc 200808992

L

Wherein the aromatic heterocyclic ring and the phosphine b are less than % of the deposited steel, and the σ substance is in contact with the original agent,

L is selected from c2-C15 dilute smoke, 匚ΓL

LyCis alkyne, nitrile, group of constituents; η is 1 or 2; R1 and R2 are independently selected from the group consisting of ruthenium, alkyl and Si(R4)3, ac-c4 alkyl, substituted by fluorine 】 _C4 wherein R is independently C ^ - CU alkane R 3 independently selected from the group consisting of CrQ, r4, ς., Λ 4 alkyl, fluorine-substituted CVC4 alkyl and (R) 3Si , wherein the inverse 4 each w subheading is independently c]-c4 alkyl, and

The reducing agent is selected from the group consisting of: 成, 、, '成之群·9-BBN (9_Bronobicyclo[3·3·1] 壬), one side burned, the BRxHh form is burnt, 1 or 2 and R is independently selected from phenyl and Cl_Ci decyl; 4 benzopyran; pyroxaline; dioxane; silane in the form of SiR, yH4_y wherein y = 〇, j, 2 or 3 and is independent Selected from phenyl and Cl_CiQ alkyl; and GeR"zH" form of decane wherein z = 〇, 1, 2 or 3 and R, independently selected from phenyl and Ci-Ci decyl. The deposition method allows for the use of relatively low temperatures (e.g., about 〇 to 2 〇〇. and produces a south quality, uniform film. The desired film is continuous and electrically conductive. These methods also provide a direct route to the copper film. In order to avoid the need to form an intermediate 113577.doc 200808992 oxide film. In the copper deposition method - in the embodiment, the core, or the hole in the substrate and / or on the hole, the surface plate of the substrate, the guide Meng Qi 刼 Hyun & amp The substrate of the company 包含 导体 包含 包含 体 体 体 体 体 体 体 体 体 体 体 体 体 体 体 体 体 体 体 体 体 体 体 基板 基板 基板 基板 基板 基板 基板 基板 基板 基板 基板 基板 基板 基板 基板 基板 基板 基板 基板The dielectric publication of the bamboo watch 侑 侑 涂 涂 涂 涂 涂 涂 k k k k k k k k k k k k k k k k k k k k k k k k k k k k k k k k k k k k k k 、, 氮化 y + 虱 虱 及 及 及 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在These methods are performed. However, in an embodiment, the substrate is preferably exposed to steel. The two-pass tantalum deposit is exposed to a ::: 吉 and then after 将 y y 瘵虱刖 by vacuum or any excess copper complex (咅 ', μ μ u, ie undeposited The complex form can be repeated after the copper is reduced, for example, by vacuum, purification, heating, rinsing or the like, or the liberation of the ligand. The method is to deposit a thicker copper layer or eliminate pinholes. = The deposition of the material is usually carried out at 2, c. The copper complex is also suspended at a similar temperature, 0 to war, and better to 50. The copper is deposited on the substrate until the copper complex is exposed to the original agent to form a metallic copper film. t. Using a re-entry reducing agent to rapidly and completely reduce the copper complex. The migration agent is volatile and does not decompose when heated. "Invasive reduction" has sufficient reducing power to react quickly with the copper complex deposited on the surface of the substrate. Applicable in the ALD method, as disclosed in the patent publication H3577.doc 200808992 WO 2004/094689 A suitable reducing agent for the reduction of copper (1). One of the agents is characterized by the presence of a proton donor. The reducing agent is desirably capable of transferring at least one electron to reduce the copper ion of the complex and capable of transferring at least one proton to protonate the coordination. It is also expected that the oxidized reducing agent and the protonated ligand can be easily removed from the surface of the newly formed copper deposit. The protonated ligand is preferably purified by vacuum, by purification or by It is removed by rinsing the surface with a suitable solvent. Suitable reducing agents for the copper deposition method include 9-BBN, borane, diboron, monobenzopyrene, sputum, smoldering, diethyl sulphur , dimethyl decane 'ethyl decane, phenyl decane, decane and dioxane. Diethyl decane and decane are preferred. In one embodiment of the copper deposition process, the copper complex is introduced into the reactor chamber containing the substrate under conditions that achieve a suitable flux temperature, time, and pressure of the vaporized complex to the surface of the substrate. room. The choice of these variables (time, T, p) will depend on the individual chamber and system design and the desired treatment rate, but as a general guideline, temperatures in the range of about ^ to 汕❶^ can be used at about 10 〇. Pressures up to 180 mTorr and periods of at least 3 sec to i minutes. After at least a portion of the copper complex is deposited on the substrate, the undeposited complex vapor is removed from the chamber (eg, by extraction or purification) and the reducing agent is at a pressure of between about 50 and 760 mT Torr A chamber is introduced to reduce the adsorbed steel complex. During the reduction, the substrate was maintained at a temperature of about 〇〇 to 2 Torr. Using a suitable combination of a copper complex and a reducing agent, the reduction is I* idling (fortunately, for most complexes, it can usually be completed in the range of 1 second to several minutes) and substantially complete (eg, complete about 95 〇 / 〇 113577.doc 200808992 =1. Ideally, in less than 1 second to several minutes of exposure time, the reduction is at least 95%. It is desirable to remove the surface from the reduction strip The product of the reaction.... In one embodiment, the copper complex is copper. The RI and the ruler 2 are ethyl, and the methyl group is called the diimine complex (1). The agent is a diethyl material. The invention also provides a novel u-diimine steel complex (1).

(I) where

The L system is selected from the group consisting of c2-Cl5 olefins and C2_Ci5 fast hydrocarbons; the nitrile, the aromatic heterocyclic ring and the phosphine η are 1 or 2;

R1 and R2 are independently selected from the group consisting of ruthenium, osmium and Si(R4)3;

CrC4 alkyl, substituted by fluorine wherein R4 are each independently CrC* alkane R3 independently selected from the group consisting of a C1-C4 alkyl group, a fluorine-substituted Ci_C4 alkyl group, and Sl(R)3, wherein each R4 is independently C "C4 alkyl. In one embodiment, L is a linear terminal olefin. For an olefin having 4 to 15 carbons 113577.doc -12 to 200808992, [L may also be an internal olefin having a cis or trans configuration, Preferably, the cis configuration is L. The ring may be a ring (tetra) or a bicyclic ring. The group may also be substituted with, for example, a decyl group. Suitable olefins include, but are not limited to, vinyl trisole, allyl trimethyl sulphur, bake, 4 _Methyl pentyl, dimethyl]-butene and norbornene. L can also be an alkyne, nitrile or such as a two-biszine, triazine or #•substituted imi, 対 or three slaves The nitrogen heterocycle can also be a phosphine.

The invention also provides a ligand of formula (II)

Where η is 1 or 2;

R1 and R2 are independently selected from the group consisting of H, Cl_C4 alkyl, fluorine-substituted Ci_c々 alkyl, and Si(R4)3, wherein R4 is each independently ^-^alkyl; R is independently selected from C1- A group consisting of a C4 alkyl group, a fluorine-substituted Ci-C4 alkyl group, and Si(R4)3, wherein each of r4 is independently a Ci_c4 alkyl group. When y is C^C:4 alkyl, it may also contain a decylene group in the alkyl chain, such as -CH2SiH2CH3 or -CH2Si(H)(CH3)CH3 or -CH2Si(CH3)2CH3. A method for synthesizing a ligand suitable for the manufacture of a copper complex is illustrated in the following examples. Thus, 1-aza-1-cycloalkylene can be deprotonated from a strong base, followed by treatment with an electrophile such as an ester or a hydrazine halide derivative to provide 113577.doc •13-200808992 for the corresponding keto group. An exocyclic enamine is used as an intermediate. The intermediate is treated with a burning agent such as dimethyl hydrazine, followed by the addition of the desired cycloheximide. Alternatively, the exocyclic ketimine can be directly coupled with the imin oxime derivative to provide the desired _diketimine oxime other ligands after strong benzalization of the 2 μ field. Similar preparation. Further, the present invention provides an article comprising a 1,3-diimine copper complex of the structure (I) deposited on a substrate. Suitable substrates include: steel, dream wafers, wafers used to fabricate very large scale integrated circuits, wafers prepared with dielectric materials having a lower dielectric constant than cerium oxide, and dioxide coated with barrier layers矽 and low-k substrate. The barrier layer can be used to prevent copper from migrating into the substrate. Suitable barrier layers include: button, nitride button, titanium, titanium nitride, button nitride, titanium tantalum nitride, button carbonitride and tantalum nitride. Examples show no additional regulations' otherwise all organic reagents were purchased from Sigma-AidHch

Corporation (Milwaiikee, WI5 USA). [Cu(CH3CN)4]S03CF3 can be produced according to the method described in: Τ·〇gUra, Transiu〇n Metai Chemistry, 1, 179-182 (976). Example 1 Preparation of aza·2_[2_(azacyclopropyl)cyclopentyl]pent-2-ene at a temperature to stir a cyclopentanone (21 g, 25 0 mmol), ethylamine (125 mL, A mixture of 2.0 g of THF in THF and dried molecular sieves (1 g) in diethyl ether (300 mL) for 3 days. The reaction mixture was filtered, and a reducing solution was applied under reduced pressure. The concentrated filtrate was distilled under vacuum (yield: 65 (1 min)) to afford 1-azacyclopentanepropane (18 g, 65%). 113577.doc -14- 200808992 7 g of 1-aza-1-cyclopentylpropane (62.9 mmol) in THF (5 mL) was added dropwise to the LDA solution (132.2 mmol) at -78 °C. , in 250 mL THF). After the mixture was stirred at -10 °C for 40 min, ethyl acetate (5.6 g, 62·9 mmol) was added. When the temperature was gradually raised to room temperature, the reaction mixture was stirred, and stirring was continued overnight at room temperature. Methanol (20 mL) was added dropwise to the mixture, followed by removal of solvent under reduced pressure. After water (200 mL) was added to the residue, mixture was extracted with diethyl ether (200 mL×2). The combined organic layers were dried over anhydrous MgSO.sub.4 then filtered. The filtrate was concentrated under reduced pressure and then purified to give 7.2 g (yield: EtOAc). A mixture of 5·5 g of β-keto enamine (35.9 mmol) and dinonyl sulfate (4.53 g, 35.9 mmol) was stirred overnight at room temperature to obtain a solidified mixture. Subsequently, ethylamine (24 mL, 46.7 mmol, 2.0 Μ in THF, 1.3 eq) was added dropwise to the mixture. The mixture was stirred overnight at room temperature. The solvent was removed under reduced pressure. After the sodium methoxide solution (1.94 g, 35.9 mmol in 20 mL of decyl alcohol) was added to the residue, the mixture was concentrated under reduced pressure. Pentane (50 mL) was added to the concentrated residue, which was then filtered. The filtrate was concentrated under reduced pressure, followed by vacuum distillation (60 ° C, 50 m s) to afford the product of <RTI ID=0.0> 78%). Example 2 Preparation and Reduction of Vinyl Trimethyldecane [3-Aza-2-[2-(azacyclopropyl)cyclopentyl]penta-2-acid] Copper in a Drying Box, 3-Aza -2-[2-(Azacyclopropyl)cyclopentyl]pent-2- 113577.doc -15- 200808992 Alkene (0.55 g5 2·77 mmol) was dissolved in diethyl ether (10 mL), then BuLi (1.63 mL, 2.77 mmol, 1.7 Torr in pentane) was added dropwise to the solution. The mixture was stirred at room temperature for 10 min. In the meantime, (:11[(::113(:]^4] SO3CF3 (1.04 g, 2.77 mmol) and vinyltrimethylnonane (0.83 g, 8.31 mmol) were mixed with diethyl ether (15 mL) The mixture was stirred at room temperature for 10 min. The butyl lithium solution was added to the copper mixture, and the resulting mixture was stirred at room temperature for 1 h. The reaction mixture was concentrated under vacuum, then pentane (30 mL) was added. The residue was filtered, and the filtrate was concentrated to give the desired product as a viscous oil (0·88 g, yield 89%). Reduction on the substrate: the viscous oil was used as the copper film on the substrate. The substrate is composed of a oxidized chip having a button layer of 25 angstroms and a copper layer of 1 angstrom. In the drying oven, about 0 04 g of copper precursor is loaded on the porcelain boat. The wafer (~1 cm2) is placed in a glass tube separated by about 3·5 。. The glass tube is removed from the drying box and connected to the vacuum line. The heating coil is connected to the area around the glass diamond, the % porcelain boat, and The area around the wafer. This configuration allows the two areas to be maintained at different temperatures. After the system is evacuated, the nitrogen = flow through The tube first flows through the sample in the boat and then flows through the wafer. The force in Lu is maintained at LUO mT〇rr. The area around the wafer is heated to 120 C. After about 1 hour, the sample boat is taken. The temperature in the surrounding area is raised to a temperature of about 2 hours, and the temperature is about 2 hours. Then, the area around the sample boat is cooled to room temperature. The tube is evacuated to a pressure of ~mT〇rr and then with diethyl decane. Filling. 11 (The area in the rc lower tube is rapidly converted to copper. Cool the unit and return to the dry box. The copper color is perceived to be darker. Repeat I13577.doc • 16 - 200808992 This method produces a crystal with a smooth copper film Example 3. Preparation of vinyltrimethylnonane [2-aza(azacyclopropyl)cyclopentyl]butan-2-acid]copper at -78C under nitrogen, n-BuLi (2.89 M, 37.6 mL, 108.1 mmol) was added dropwise to a solution of diisopropylamine (1 〇·9 g, l 〇 8 l in mL). After all n_BuLi was added, the temperature was adjusted to 5 C and the reaction mixture was stirred 3 0 Then, a solution of 1-aza-1-cyclopentylpropane (5 g, 51·5 mmol) in THF (10 mL) was added dropwise at -5 °C. The reaction mixture was stirred, and after 30 min, methyl thioacetamide (5.3 g, 5 1.5 mmol) was added dropwise at -30 C for 30 min. While warm, stir the reaction mixture' and then continue stirring at room temperature overnight. After removing THF^d under reduced pressure, add 30 mL of decyl alcohol dropwise to the residue. After removing all volatile solvents, Pentane (50 mL x 2) was added to the residue and the mixture was filtered. The filtrate was concentrated under reduced pressure, followed by vacuum distillation (55 ° C, 6 〇m Torr) affording 5.3 g of 2-aza-3-[2-(aza-propylidene)cyclopentyl]but-2-ene ( 62%). In a dry box, aza_3·[2_(azacyclopropyl)cyclopentyl]but-2-ene (0.3 g5 ι·8 mmol) was dissolved in diethyl ether (15 mL), followed by BuLi (l · 06 mL, 1.80 mmol, 1 · 7 Μ in Ethanol) Add dropwise to the solution. The mixture was stirred at room temperature for 1 〇 min. In the meantime, Cu[(CH3CN)d SO3CF3 (0.67 g, ι·8〇mmol) and ethylene trimethyl sulphate (0.90 g, 9·0 mmol) were mixed together in diethyl ether (15 mL), and in the room. The mixture was stirred at room temperature for 5 min. The butyl solution was added to the copper mixture and the resulting mixture was stirred for 40 min at room temperature 113577.doc • 17-200808992. The reaction mixture was concentrated under vacuum, then decane (30 mL) was then evaporated. Filtration, followed by EtOAc EtOAc (EtOAc)

113577.doc 18·

Claims (1)

200808992 X. Patent Application Range: 1 . A method for forming a steel deposit on a substrate, comprising: a. contacting a substrate with a copper complex (1) to form a deposited copper complex on the substrate; and ' b. contacting the deposited steel complex with a reducing agent, wherein: L is selected from the group consisting of C2-C15 olefins, c2_Cl5 hydrocarbons, nitriles, aromatic heterocycles, and phosphines; η is 1 or 2; R1 and R2 is independently selected from the group consisting of H, Ci_C4 alkyl, fluoro substituted alkyl and Si(R4)3, wherein R4 are each independently alkyl; R3 is independently selected from Cl-C4 alkyl, substituted by fluorine a Ci_C4 alkyl group and Si (R, wherein R4 are each independently selected from a Cj_C4 alkyl group; and the reducing agent is selected from the group consisting of 9-borobicyclo[3·3ι] decane, diborane; a borane of the form BRxH3_x wherein χ=〇, 1 or 2 and the sizing is independently selected from the group consisting of phenyl and Cl-C1G alkyl; dihydrophenylhydrazine; pyrazoline; dioxane; SiR'yHoB-type decane wherein y= :(), 1, 2 or 3 and R' is independently selected from phenyl and CVCw alkyl; and GeR"zH4 z form 锗113577.doc 200808992 burns therein, 1 2 as a branch, 2 or 3 and R' 'Independently selected from phenyl and CVCw alkyl. The method of Shan Yongxiang!, where R 3. as the method of the requester, wherein R, methyl. 4. As the method of the request item, wherein _b 5· Request item 6· Please, the method, wherein B is vinyl trimethyl decane. The method of pulling, 1, wherein the substrate is selected from the group consisting of copper, germanium wafers and cerium oxide coated with an early P layer. 1 $ f ^ , ^ ', the contact in the eighth includes exposing the substrate to the vapor of the copper complex. 8» As in claim 1 y , , /, the method is in the range of 〇 to 200. Go to 0 9 · as requested in item 1 | Burn. Go to 'where the reducing agent is me or diethyl 夕 〇 1 · · steel complex (1), among them a C2-C15 block hydrocarbon, a nitrile pentene ring and [selected from the group consisting of c2-c15 olefins, phosphine; 113577.doc 200808992 η is 1 or 2; and R1 and R2 are independently selected from H, Ci_C4 alkyl, a group consisting of a fluorine-substituted alkyl group and SKR4)3, wherein each f is independently an alkyl group; and R3 is independently selected from a Ci_C4 alkyl group, a fluorine-substituted Ci_C4 alkyl group, and Si (R, wherein R4 is independently Is selected from the group consisting of Ci_c4 alkyl. 11. The copper complex (1) of claim 10, wherein B is vinyl trimethylnonane; R1 and R2 are methyl or ethyl and R3 is methyl. 12. The species 1112 is produced by contacting a substrate with a steel complex as in claim 1 . 13. The article of claim 12, wherein the substrate is selected from the group consisting of copper, tantalum wafers, and ruthenium dioxide coated with a barrier layer. 14. The article of claim 13, wherein the barrier layer is selected from the group consisting of a group, a nitrided group, titanium, titanium nitride, (iv) nitride, a tantalum nitride, a group carbonitride, and a nitride. 15·—a composition of the formula (II), Wherein η is 1 or 2; 113577.doc f 200808992 R1 and R2 are independently selected from the group consisting of hydrazine, CrQ alkyl, fluorine-substituted Ci-C# alkyl and Si(R4)3, wherein R4 is independently CrQ alkyl; and R3 are independently selected from alkyl, fluorine-substituted CrQ alkyl and Si(R4)3, wherein each R4 is independently selected from CVC4 alkyl. 113577.doc 200808992 VII. Designated representative map: (1) The representative representative of the case is: (none) (2) The symbolic symbol of the representative figure is simple: 8. If there is a chemical formula in this case, please reveal the best indication of the characteristics of the invention. Chemical formula: 113,577.doc