WO2004101651A1

WO2004101651A1 - Minimization of coating defects for compositions comprising silicon-based compounds and methods of producing and processing

Info

Publication number: WO2004101651A1
Application number: PCT/US2004/014317
Authority: WO
Inventors: William Bedwell; Songyuan Xie; Jelena Sepa; Anh Duong; Nancy Iwamoto; Paul Apen; Roger Leung
Original assignee: Honeywell International Inc.
Priority date: 2003-05-08
Filing date: 2004-05-07
Publication date: 2004-11-25

Abstract

Polymer solutions are described herein that comprise: a) at least one silicon-based polymer having high molecular weight species and low molecular weight species after solvation with a compatible primary solvent, wherein the low molecular weight species crystallize in or precipitate out of the polymer solution; b) a primary solvent that solvates the high molecular weight species in the solution; and c) at least one additional solvent that solvates the low molecular weight species in the solution. Methods of producing a polymer solution are also described herein that comprise: a) providing at least one silicon-based polymer having high molecular weight species and low molecular weight species after solvation with a compatible primary solvent, wherein the low molecular weight species crystallize in or precipitate out of the polymer solution; b) providing a primary solvent that solvates the high molecular weight species in the solution; c) providing at least one additional solvent that solvates the low molecular weight species in the solution; and d) blending the at least one silicon-based polymer, the primary solvent and the at least one additional solvent to form the polymer solution. Methods of processing a polymer solution include: a) providing a filtration method or device, b) providing a polymer solution comprising high molecular weight species and low molecular weight species, wherein the low molecular weight species are in the form of crystals or precipitates, and c) utilizing the filtration method or device to filter the low molecular weight species out from the polymer solution.

Description

MINIMIZATION OF COATING DEFECTS FOR COMPOSITIONS COMPRISING SILICON-BASED COMPOUNDS AND METHODS OF PRODUCING AND PROCESSING

BACKGROUND OF THE SUBJECT MATTER

5 Electronic and semiconductor components are used in ever-increasing numbers of consumer and commercial electronic products, communications products and data-exchange products. Examples of some of these consumer and commercial products are televisions, computers, cell phones, pagers, palm-type or handheld organizers, portable radios, car stereos, or remote controls. As the demand for these consumer and commercial electronics increases,

10 there is also a demand for those same products to become smaller and more portable for the consumers and businesses.

As a result of the size decrease in these products, the components that comprise the products must also become smaller and/or thinner. Examples of some of those components that need to be reduced in size or scaled down are microelectronic chip interconnections, 5 semiconductor chip components, resistors, capacitors, printed circuit or wiring boards, wiring, keyboards, touch pads, and chip packaging.

When electronic and semiconductor components are reduced in size or scaled down, any defects that are present in the larger components are going to be exaggerated in the scaled down components. Thus, the defects and discontinuities that are present or could be present 0 in the larger component should be identified and corrected, if possible, before the component is scaled down for the smaller electronic products.

In order to identify and correct defects in electronic, semiconductor and communications components, the components, the materials used and the manufacturing processes for making those components should be broken down and analyzed. Electronic, 5 semiconductor and communication/data-exchange components are composed, in some cases, of layers of materials, such as metals, metal alloys, ceramics, inorganic materials, polymers, or organometallic materials. The layers of materials are often thin (on the order of less than a few tens of angstroms in thickness). In order to improve on the quality of the layers of materials, the process of forming the layer - such as physical vapor deposition of a metal or 0 other compound - should be evaluated and, if possible, modified and improved. In an effort to increase the performance and speed of semiconductor devices, semiconductor device manufacturers have sought to reduce the linewidth and spacing of interconnects while minimizing the transmission losses and reducing the capacitative coupling of the interconnects. One way to diminish power consumption and reduce capacitance is to decrease the dielectric constant (also referred to as "k") of the insulating material, or dielectric, that separates the interconnects. Insulator materials having low dielectric constants are especially desirable, because they typically allow faster signal propagation, reduce capacitance and cross talk between conductor lines, and lower voltages required for driving integrated circuits. Therefore, as interconnect linewidths decrease, concomitant decreases in the dielectric constant of the insulating material are required to achieve the improved performance and speed desired of future semiconductor devices. For example, devices having interconnect linewidths of 0.13 or 0.10 micron and below seek an insulating material having a dielectric constant (k) < 3. Semiconductor device manufacturers also seek materials that in addition to having a low dielectric constant, have the mechanical and thermal stability needed to withstand the thermal cycling and processing steps of semiconductor device manufacturing.

In a typical damascene process, a line pattern is etched in the surface of a insulating material, and the trenches formed in this manner, i.e., the horizontal structure created to house the horizontal electrical connections within a particular level or layer in a semiconductor device, is filled with copper by electroplating, electroless plating, or sputtering. After the copper is deposited onto the entire surface, a chemical-mechanical planarization (CMP) step is employed to remove excess copper, and to planarize the wafer for subsequent processing steps. This process is typically repeated several times to form vias, i.e., the vertical structures created to contain the vertical electrical connections that connect the trenches between at least two metal levels or layers of metal in a semiconductor device.

To further improve the damascene process, via and line formation can be integrated into a single process, which is then called dual damascene process. In the dual damascene process, a via dielectric layer is laid down onto a substrate, and the via dielectric layer is subsequently coated with a patterned etch stop layer, i.e., a layer that controls the etching or removal of the dielectric, whereby voids in the etch stop layer correspond to positions of vias that will be etched into the via dielectric. In a next step, a line dielectric is deposited onto the etch stop layer, which in turn is coated with a patterned hardmask layer that defines the traces of the lines. Current hardmask layers are made of silicon nitride, silicon oxynitride, silicon oxide, or silicon carbide. In a following step via and line traces are formed, whereby the line trenches are etched into the line dielectric until the etchant reaches the etch stop layer. In positions where there is no etch stop layer, the etching process continues through the via dielectric to form a via. As in the damascene process, etched via and line traces are filled with copper (after applying a Ta(N) barrier layer and a Cu-seed layer) and a CMP step finishes the dual damascene process.

Dielectric etching is difficult to control with today's required trench width of 0.13 micron. Thus, the etch stop performs a critical role in semiconductor device construction. A disadvantage of known hardmask and etch stop materials is their relatively high dielectric constant (k-value). For example, typical hardmask and etch stop materials, including SiN,

SiON, SiO.sub.2, and SiC, have an undesirably high dielectric constant of at least about 4.0 and are applied by chemical vapor deposition (CVD). Although J. J. Waeterloos et al., "Integration of a Low Permittivity Spin-on Embedded Hardmask for Cu/SiLK Resin Dual

Damascene", Proceedings of the IEEE 2001 International Interconnect Technology

Conference, pages 60-62 (Jun. 4-6, 2001) teaches that a low-k spin-on organosiloxane film may replace the preceding known etch stop materials to lower the effective k value, the article reports that the organosiloxane film has a k value of 3.2 and does not disclose any details about the organosiloxane used.

U.S. Pat. No. 4,626,556 teaches organosilsesquioxane having required alkyl and alkenyl group side chains bonded thereto and optionally aryl groups and hydrogen side chains bonded thereto as a substitute for a photoresist material. U.S. Pat. No. 4,626,556 does not teach that its organosilsesquioxane may function as an etch stop or hardmask. In Comparative A below, we made an organosilsesquioxane having the required minimum at least 50% methyl groups of U.S. Pat. No. 4,626,556 and this material did not wet known dielectric materials and thus, would not be useful as an etch stop. Although U.S. Pat. No. 4,626,556 teaches that its organosilsesquioxane films have low dielectric constants, U.S. Pat. No. 4,626,556 does not report any dielectric constant values. However, as those skilled in the art know, silanol results in an undesirable dielectric constant and U.S. Pat. No. 4,626,556's organosilsesquioxane transmission FTIR plots show that silanol (3400-3700/cm) is present. Also, U.S. Pat. No. 4,626,556 teaches in a preferred embodiment, the presence of a crosslinking agent that is light activated and as those skilled in the art know, that these materials have high dielectric constants. Also, U.S. Pat. No. 4,626,556 teaches that at least 50% of its side chains are alkyl groups since the larger the amount of the alkyl group present, the higher the heat resistance U.S. Pat. No. 4,626,556's Examples 13 and 14 teach that its organosilsesquioxane was applied to a two inch thick silicone wafer wherein a thin film of one micron was formed; the film was then heated at 250°C for 2 hours, at 350°C for 1 hour, and then at 450 °C for 30 minutes, and subjected to thermogravimetric analysis, in which no weight loss was observed up to 600 °C. It is not clear if the silicone wafer weight was included in the "no weight loss" reported. Generally, conventional semiconductor manufacturers require a more stringent TGA test of a film alone and not on a wafer. This current more stringent TGA test requires heating and holding at 200 °C - where weight loss represents how well the material was dried; holding at 430 °C for 90 minutes - where weight loss represents worst case scenario for shrinkage from low temperature bake to high temperature cure; and heating at 450 °C - where weight loss represents thermal stability. Thus, U.S. Pat. No. 4,626,556's organosilsesquioxane does not have the wetting characteristics, low dielectric constant, and thermal stability required by today's semiconductor manufacturers.

In 1999, AlliedSignal Inc., now Honeywell International Inc., introduced a HOSP™ product comprising organosiloxane having about 80% methyl groups and 20% hydrogen groups. US Patent Publication 2001/006848A1 published Jul. 5, 2001 teaches that

AlliedSignal's HOSP™ product is useful as a hardmask. Unfortunately this product generally does not have acceptable wetting properties with organic dielectrics.

Commonly assigned U.S. Pat. Nos. 5,973,095; 6,020,410; 6,043,330; 6,177,143; and 6,287,477 teach organohydridosiloxane resins of the formula (Ho. -ι.oSiOι._5-ι.₈)_n(Ro._4-ι.oSiOι._5- ι.8)m where R is alkyl groups, aryl groups, and mixtures thereof. See also commonly assigned U.S. Pat. No. 6,015,457. Unfortunately a composition comprising 50% phenyl groups and 50% hydrogen subjected to the current stringent TGA test had a weight loss of 1.0 percent per hour. Generally, when thin films (e.g. about 5θA to about 5000A) are made from siloxane- based polymers and compositions, microscopic deformities or defects may form (up to about 2-3 million per wafer) during the casting process whereby the polymer or composition is cast onto a silicon wafer using a spin-on application process where the composition or polymer is formed into a dilute solution (1% to 10% polymer) and spun onto a wafer. These discontinuities and defects can lead to failures during the manufacturing of interconnect circuits for semiconductor devices.

Thus, a need still exists in the semiconductor industry to provide: a) compositions with lower dielectric constants; b) compositions that can form layers and films with improved mechanical properties, such as thermal stability, glass transition temperature (Tg), and hardness; c) compositions that are capable of being solvated and spun-on to a wafer or layered material with minimal defects and discontinuities as compared to conventional compositions; and d) compositions that are versatile enough to function as a hardmask or an etch stop and can wet dielectric materials.

SUMMARY OF THE SUBJECT MATTER

Polymer solutions are described herein that comprise: a) at least one silicon-based polymer having high molecular weight species and low molecular weight species after solvation with a compatible primary solvent, wherein the low molecular weight species crystallize in or precipitate out of the polymer solution; b) a primary solvent that solvates the high molecular weight species in the solution; and c) at least one additional solvent that solvates the low molecular weight species in the solution.

Methods of producing a polymer solution are also described herein that comprise: a) providing at least one silicon-based polymer having high molecular weight species and low molecular weight species after solvation with a compatible primary solvent, wherein the low molecular weight species crystallize in or precipitate out of the polymer solution; b) providing a primary solvent that solvates the high molecular weight species in the solution; c) providing at least one additional solvent that solvates the low molecular weight species in the solution; and d) blending the at least one silicon-based polymer, the primary solvent and the at least one additional solvent to form the polymer solution.

Methods of processing a polymer solution include: a) providing a filtration method or device, b) providing a polymer solution comprising high molecular weight species and low molecular weight species, wherein the low molecular weight species aTe in the form of crystals or precipitates, and c) utilizing the filtration method or device to filter the low molecular weight species out from the polymer solution.

BRIEF DESCRIPTION OF THE FIGURE AND TABLES

Figure 1 shows expected solubility parameters versus the molecular weight of several silicon- based polymers.

Table 1 shows the results of the molecular weight fractionation experiments. Table 2 shows a tabular representation of data collected utilizing a contemplated embodiment.

Table 3 shows a tabular representation of data collected utilizing a contemplated embodiment.

Table 4 shows a tabular representation of data collected utilizing a contemplated embodiment.

Table 5 shows a tabular representation of data collected utilizing a contemplated embodiment.

Table 6 shows solvent solubility parameters described in Example 2.

Table 7 shows the results of filtration experiments in Example 3.

DESCRIPTION OF THE SUBJECT MATTER

In order to improve the process of depositing a layer of material, the surface or material composition must be measured, quantified and defects or imperfections detected. In the case of the deposition of a layer or layers of material, its not the actual layer or layers of material that should be monitored but the material and surface of that material that is being used to produce the layer of material on a substrate or other surface that should be monitored. For example, when depositing a polymer solution on a wafer, the solution must be analyzed and monitored to determine if the ratio of polymer(s) to solvents) in the solution is adequate to ensure that defects and discontinuties are minimized or eliminated altogether. One of the analytical techniques used to evaluate a polymer, polymer mixture or polymer composition is to analyze the solubility properties of the polymer, polymer mixture or polymer composition and the molecular weight distribution of the polymer, polymer mixture or polymer composition. Molecular weight distribution is a property that is a subset of the solubility properties of a polymer, polymer mixture or polymer composition. A thorough review of the molecular weight distribution of a polymer, polymer mixture or polymer composition can yield beneficial results when trying to eliminate defects and/or discontinuities on the coated silicon wafer. For example, it is now known that the suspect portion of the molecular weight distribution for a siloxane-based polymer, polymer mixture and/or polymer composition is the low end of the molecular weight distribution, which comprises symmetrical cage (T8, T10, T12...) structures. These cage structures can form precipitates and crystals, which are likely the discontinuities observed in the polymer films. It has been discovered that adjusting the composition of the casting solution (i.e. polymer, polymer mixture and/or polymer composition solution) allows one to control the solubility of the low molecular weight species, and therefore the incidence of defects during the coating process. Specifically, cosolvents may be prepared and blended to manage defect solubility in silicon-based polymer solutions and pretreatments may be used to remove some of the defect-causing species.

Compositions and solutions are described herein that a) have lower dielectric constants; b) form layers and films with improved mechanical properties, such as thermal stability, glass transition temperature (T_g), and hardness; c) are capable of being solvated and spun-on to a wafer or layered material with minimal defects and discontinuities as compared to conventional compositions; and d) are versatile enough to function as a hardmask or an etch stop and can wet dielectric materials. A contemplated polymer solution that meets at least these goals comprises at least one silicon-based polymer, polymer mixture and/or polymer composition, at least one primary solvent comprising propylene glycol methyl ether acetate and at least one additional solvent.

Silicon-based compounds and polymers comprise siloxane compounds and siloxane- based polymers, such as methylsiloxane, methylsilsesquioxane, phenylsiloxane, phenylsilsesquioxane, methylphenylsiloxane, methylphenylsilsesquioxane, silazane polymers, dimethylsiloxane, diphenylsiloxane, methylphenylsiloxane, silicate polymers, silsilic acid derivaties, and mixtures thereof. A contemplated silazane polymer is perhydrosilazane. Many of these contemplated polymers and compounds are found in US Application Publication No.: 2003/0031789 Al, which is commonly-owned and herein incorporated by reference in its entirety.

Other contemplated silicon-based polymers and blockpolymers comprise hydrogensiloxane polymers of the general formula (Ho-ι.oSiOι.s.2.o)x, hydrogensilsesquioxane polymers, which have the formula (HSiOι.5)_x, where x is greater than about four and derivatives of silsilic acid. Also included are copolymers of hydrogensilsesquioxane and an alkoxyhydridosiloxane or hydroxyhydridosiloxane.

Additional silicon-based polymers contemplated herein include organosiloxane polymers, acrylic siloxane polymers, silsesquioxane-based polymers, derivatives of silicic acid, organohydridosiloxane polymers of the general formula (Ho-ι,oSiOι._5-2.o)_n(Ro-ι.oSiOι.₅..

₂.o)_m> and organohydridosilsesquioxane polymers of the general formula (HSiOι.5)_n(RSiOι.₅)_m, where m is greater than zero and the sum of n and m is greater than about four and R is alkyl or aryl. Some useful organohydridosiloxane polymers have the sum of n and m from about four to about 5000 where R is a C₁-C₂₀ alkyl group or a Cβ-Cπ aryl group. The organohydridosiloxane and organohydridosilsesquioxane polymers are alternatively denoted spin-on-polymers. Some specific examples include alkylhydridosiloxanes, such as methylhydridosiloxanes, vinylhydridosiloxanes, ethylhydridosiloxanes, propylhydridosiloxanes, t-butylhydridosiloxanes, phenylhydridosiloxanes; and alkylhydridosilsesquioxanes, such as mefhylhydridosilsesquioxanes, ethylhydridosilsesquioxanes, propylhydridosilsesquioxanes, t-butylhydridosilsequioxanes, phenylhydridosilsesquioxanes, and combinations thereof. ,

In some contemplated embodiments, specific organohydridosiloxane resins utilized herein have the following general formulas:

[H-Sii.s]„[R-SiOi.s]_m Formula (1)

[Ho.5-Sii.₅ - ι.8jn[Ro.5-ι.o-SiOι.5 - j.g]_m Formula (2)

[Ho-ι.o-Si,.₅]_n[R-SiOι.₅]_m Formula (3)

[H-Siι.₅]_x[R-SiOι.s3y[Si0₂]_z Formula (4)

wherein: the sum of n and m, or the sum or x, y and z is from about 8 to about 5000, and m or y is selected such that carbon containing constituents are present in either an amount of less than about 40 percent (Low Organic Content = LOSP) or in an amount greater than about 40 percent (High Organic Content = HOSP); R is selected from substituted and unsubstituted, normal and branched alkyls (methyl, ethyl, butyl, propyl, pentyl), alkenyl groups (vinyl, allyl, isopropenyl), cycloalkyls, cycloalkenyl groups, aryls (phenyl groups, benzyl groups, naphthalenyl groups, anthracenyl groups and phenanthrenyl groups), and mixtures thereof; and wherein the specific mole percent of carbon containing substituents is a function of the ratio of the amounts of starting materials. In some LOSP embodiments, particularly favorable results are obtained with the mole percent of carbon containing substituents being in the range of between about 15 mole percent to about 25 mole percent. In some HOSP embodiments, favorable results are obtained with the mole percent of carbon containing substituents are in the range of between about 55 mole percent to about 75 mole percent. In another embodiment, an organosiloxane compound and/or composition having alkenyl groups and thermal stability is provided and may be utilized in the polymer solutions described herein. The phrase "substantially no silanol" as used herein excludes the presence of silanol as evidenced by FTffi. silanol peaks taught by U.S. Pat. No. 4,626,556, The term "organosiloxane" as used herein means silicon and carbon-containing compounds, includes organosilsesquioxane, and excludes the presence of crosslinking agent activated by light as taught by U.S. Pat. No. 4,626,556. The phrase "thermal stability" as used herein means less than 0.5 percent weight loss at 450°C.

Several contemplated polymers comprise a polymer backbone encompassing alternate silicon and oxygen atoms. In contrast with previously known organosiloxane resins, some of the polymers and inorganic-based compositions and materials utilized herein have essentially no hydroxyl or alkoxy groups bonded to backbone silicon atoms. Rather, each silicon atom, in addition to the aforementioned backbone oxygen atoms, is bonded only to hydrogen atoms and/or R groups as defined in Formulae 1 , 2, 3 and 4. By attaching only hydrogen and/or R groups directly to backbone silicon atoms in the polymer, unwanted chain lengthening and cross-linking is avoided. And given, among other things, that unwanted chain lengthening and cross-linking is avoided in the resins of the present invention, the shelf life of these resin solutions is enhanced as compared to previously known organosiloxane resins. Furthermore, since silicon-carbon bonds are less reactive than silicon hydrogen bonds, the shelf life of the organohydridosiloxane resin solutions described herein is enhanced as compared to previously known hydridosiloxane resins.

Additional contemplated organosiloxane compounds and compositions comprise the compound of Formula 5:

[Yθ.01-l.θSiOl.5_-2]a[Zo.ol-l.θSiOl.5-2]b[Ho.ol-l.θSiOι.5_-2]c

where Y is aryl; Z is alkenyl; a is from 15 percent to 70 percent of Formula 5; b is from 2 percent to 50 percent of Formula 5; and c is from 20 percent to 80 percent of Formula 5.

Unlike alkyl-containing materials similar to those taught in U.S. Pat. No. 4,626,556 that do not wet known dielectric materials, the composition taught in Formula 5 wets dielectric materials as reported in our Examples below and also incorporated herein by reference and thus, may be advantageously used as an etch stop. Contrary to U.S. Pat. No. 4,626,556's teaching that its organosilsesquioxane requires the presence of alkyl groups for heat resistance and does not require the presence of aryl groups, we have discovered that the present composition requiring the presence of aryl groups but not requiring the presence of alkyl groups has good thermal stability as evidenced by the TGA results reported below. The present composition also has a dielectric constant of preferably less than about 3.2. Another benefit of the present composition is that it has a low crosslinking temperature. The present composition may contain up to 20 weight percent of other units as long as the other units do not detract from the desirable properties of the present composition. Contemplated polymers comprise a polymer backbone encompassing alternate silicon and oxygen atoms. In Formula 5, preferably Y is phenyl, benzyl, substituted phenyl, naphthyl, anthryl, and phenanthryl. In Formula 5, preferably Z is vinyl, substituted vinyl, vinyl ether, acrylate, and methacrylate. In Formula 5, preferably a is from 30 percent to 70 percent of Formula 5 and b is from 10 percent to 40 percent of Formula 5. Polymers contemplated herein may be produced with or without hydroxyl or alkoxy groups bonded to backbone silicon atoms. Preferably, each silicon atom, in addition to the aforementioned backbone oxygen atoms, is bonded only to hydrogen atoms and/or Y groups or Z groups as defined in Formula 5. By attaching only hydrogen and/or Y and Z groups directly to backbone silicon atoms in the polymer, unwanted chain lengthening and cross- linking is avoided. And given, among other things, that unwanted chain lengthening and cross-linking is avoided in the resins contemplated herein, the shelf life of these resin solutions is enhanced as compared to previously known organosiloxane resins. Furthermore, since silicon-carbon bonds are less reactive than silicon-hydrogen bonds, the shelf life of the organosiloxane resin solutions described herein is enhanced as compared to previously known hydridosiloxane resins. Preferably, the present organosiloxane compounds and compositions have a molecular weight from about 1,000 to about 100,000.

In some contemplated embodiments, the polymer backbone conformation is a cage configuration. Accordingly, there are only very low levels or reactive terminal moieties in the polymer resin given the cage conformation. A cage conformation of the polymer backbone also ensures that no unwanted chain lengthening polymerization will occur in solution, resulting in an extended shelf life. Each silicon atom of the polymer is bonded to at least three oxygen atoms. Moieties bonded to the polymer backbone include hydrogen and the organic groups described herein. As used herein, the term "backbone" refers to a contiguous chain of atoms or moieties forming a polymeric strand that are covalently bound such that removal of any of the atoms or moiety would result in interruption of the chain. Some of the contemplated compounds previously mentioned are taught by commonly assigned US Patent 6,143,855 and pending US Serial No. 10/078919 filed February 19, 2002; Honeywell International Inc.'s commercially available HOSP®product; nanoporous silica such as taught by commonly assigned US Patent 6,372,666; Honeywell International Inc.'s commercially available NANOGLASS®E product; organosilsesquioxanes taught by commonly assigned WO 01/29052; and fluorosilsesquioxanes taught by commonly assigned US Patent 6,440,550, incorporated herein in their entirety. Other contemplated compounds are described in the following issued patents and pending applications, which are herein incorporated by reference in their entirety: (PCT/USOO/l 5772 filed June 8, 2000; US Application Serial No. 09/330248 filed June 10, 1999; US Application Serial No. 09/491166 filed June 10, 1999; US 6,365,765 issued on April 2, 2002; US 6,268,457 issued on July 31, 2001; US Application Serial No. 10/001143 filed November 10, 2001; US Application Serial No. 09/491166 filed January 26, 2000; PCT/US00/00523 filed January 7, 1999; US 6,177,199 issued January 23, 2001; US 6,358,559 issued March 19, 2002; US 6,218,020 issued April 17, 2001; US 6,361,820 issued March 26, 2002; US 6,218,497 issued April 17, 2001; US 6,359,099 issued March 19, 2002; US 6,143,855 issued November 7, 2000; US Application Serial No. 09/611528 filed March 20, 1998; and US Application Serial No. 60/043,261). Silica compounds contemplated herein are thpse compounds found in US Issued Patents: 6,022,812; 6,037,275; 6,042,994; 6,048,804; 6,090,448; 6,126,733; 6,140,254; 6,204,202; 6,208,041; 6,318,124 and 6,319,855. As used herein, the term "crossliriking" refers to a process in which at least two molecules, or two portions of a long molecule, are joined together by a chemical interaction. Such interactions may occur in many different ways including formation of a covalent bond, formation of hydrogen bonds, hydrophobic, hydrophilic, ionic or electrostatic interaction. Furthermore, molecular interaction may also . be characterized by an at least temporary physical connection between a molecule and itself or between two or more molecules. As used herein, the term "monomer" refers to any chemical compound that is capable of forming a covalent bond with itself or a chemically different compound in a repetitive manner. The repetitive bond formation between monomers may lead to a linear, branched, super-branched, or three-dimensional product. Furthermore, monomers may themselves comprise repetitive building blocks, and when polymerized the polymers formed from such monomers are then termed "blockpolymers". Monomers may belong to various chemical classes of molecules including organic, organometallic or inorganic molecules. The molecular weight of monomers may vary greatly between about 40 Dalton and 20000 Dalton. However, especially when monomers comprise repetitive building blocks, monomers may have even higher molecular weights. Monomers may also include additional groups, such as groups used for crosslinking.

The silicon-based compositions may be synthesized with a dual phase solvent system using a catalyst. The starting materials encompass trichlorosilane and a combination of organotrichlorosilanes including alkenyl or aryl substituted trichlorosilane. The relative ratios of the trichlorosilane and the organotrichlorosilane determine the mole percent carbon- containing substituents in the polymer. As an example, a contemplated method is as follows:

Mix a solution of hydridotrihalosilanes and organic-substituted trihalosilanes (e.g. trichlorosilane and alkenyl or aryltrichlorosilane) to provide a mixture. Combine the mixture with a dual phase solvent including a non-polar solvent, and a polar solvent to provide a dual phase reaction mixture. Add a solid phase catalyst to the silane/solvent reaction mixture. React the silanes to produce organohydridosiloxanes. Recover the organosiloxane from the organic portion of the dual phase solvent system. Additional steps may include washing the recovered organosiloxane to remove any unreacted monomer, and fractionating the organosiloxane product to thereby classify the product according to molecular weight.

A catalyst used as a phase transfer catalyst may be used such as tetrabutylammonium chloride, and benzyltrimethylammonium chloride. The phase transfer catalyst is introduced into the reaction mixture and the reaction is allowed to proceed to the desired degree of polymerization. As used herein, the term "catalyst" means any substance that affects the rate of the chemical reaction without itself being consumed or undergoing a chemical change. Catalysts may be inorganic, organic, or a complex of organic groups and metal halides. Catalysts may also be liquids, solids, gases or a combination thereof.

A dual phase solvent system including a continuous phase non-polar solvent and a polar solvent may be used. The non-polar solvent includes, but is not limited to, any suitable alkyl, alkenyl or aryl compounds or a mixture of any or all such suitable compounds, the operational definition of "suitable" in the present context includes the functional characteristics of: 1) solubilizing the monomeric silicon compounds, 2) solubilizing the resin product, 3) stability of the resin product in the solvent, and 4) insolubility of unwanted reaction products.

Contemplated solvents include any suitable pure or mixture of organic, organometallic or inorganic molecules that are volatilized at a desired temperature, such as the critical temperature. The solvent may also comprise any suitable pure or mixture of polar and non- polar compounds. In preferred embodiments, the solvent comprises water, ethanol, propanol, acetone, ethylene oxide, benzene, toluene, ethers, cyclohexanone, butryolactone, methylethylketone, and anisole. As used herein, the term "pure" means that component that has a constant composition. For example, pure water is composed solely of H₂0. As used herein, the term "mixture" means that component that is not pure, including salt water. As used herein, the term "polar" means that characteristic of a molecule or compound that creates an unequal charge, partial charge or spontaneous charge distribution at one point of or along the molecule or compound. As used herein, the term "non-polar" means that characteristic of a molecule or compound that creates an equal charge, partial charge or spontaneous charge distribution at one point of or along the molecule or compound. Particularly preferred solvents include, but are not limited to, pentane, hexane, heptane, cyclohexane, benzene, toluene, xylene, halogenated solvents such as carbon tetrachloride, and mixtures thereof.

The second solvent phase is a polar phase, immiscible with the organic, non-polar solvent phase, and includes water, alcohols, and alcohol and water mixtures. It is thought that alcohol solubilizes reactive intermediates that are not yet soluble in the non-polar phase and would ordinarily be unstable in a substantially aqueous phase. The amount of alcohol present is, however, not so high as to significantly dissolve product polymers having molecular weights greater than about 400 AMUs.

Alcohols and other polar solvents suitable for use in the polar phase include, but are not limited to, water, methanol, ethanol, isopropanol, glycerol, diethyl ether, tetrahydrofuran, diglyme, and mixtures thereof. In one embodiment, the polar solvent includes a water/alcohol mixture wherein the water is present in an amount sufficient to preferentially solubilize ionic impurities not soluble in alcohol, and/or preclude solvent extraction of product compounds that might otherwise be soluble in alcohol. The polar solvent phase advantageously retains the hydrochloric acid (HC1) condensation product and any metal salt or other ionic contaminants that may be present. Since any ionic contaminants are retained in the polar solvent phase, the organosiloxane product contemplated herein is of high purity and contains essentially no metal contaminants.

In another embodiment of the method disclosed herein, a solid phase catalyst and/or ion exchange resin, such as the AMBERJET 4200™ or AMBERLITE 1-6766™ ion exchange resins (both available from Rohm and Hass Company, Philadelphia, Pa.), surface catalyzes the polymerization of the trihalosilane and organo-trihalosilane monomers into the composition of this invention. AMBERJET 4200™ is a basic anion exchange resin based on the chloride ion. AMBERLITE 1-6766™ is also a basic anion exchange resin. By way of explanation, and not by way of limitation, it is thought polymer chain propagation occurs on the catalyst surface by hydrolysis of the Si— CI bond of the monomer to Si—OH, followed by condensation with another Si-OH to provide an Si— O— Si bond, thereby extending the polymer chain. In other embodiments, polymerization is catalyzed with a phase transfer catalyst such as tetrabutylammonium chloride.

The resulting silicon-based composition/solvent solution is then filtered under ambient conditions via any of the filtration devices well known in the art. It is generally preferable to use a filtration device having a pore size less than about 1 μm. A typical filtration process uses a pore size in the range of about 0.1 μm to about 0.0 lμm.

In conventional applications, once the at least one silicon-based polymer is synthesized or provided, it is solvated in a solvent. However, in these applications there are either two conditions: a) the silicon-based polymer is present in solution in a weight-percent of greater than 40% in solution or b) the silicon-based polymer is present in one solvent that is compatible with the polymer. The conventional art does not have low concentrations of silicon-based polymers in a solution with a primary solvent that solvates the higher molecular weight silicon-based polymers and at least one additional solvent, wherein the at least one additional solvent displaces and/or dissolves the materials in the polymer solution that are directly attributed to the defects in the final film or layer, such as the lower molecular weight species.

In the present subject matter, it has been discovered that once the at least one silicon- based polymer and/or composition is either synthesized or provided, the at least one silicon- based polymer may be present in the polymer solution has a concentration range of less than about 25% by weight in the solution. In other contemplated embodiments, the at least one silicon-based polymer is present in the polymer solution at a concentration range of less than about 20%, and in yet other contemplated embodiments, the at least one silicon-based polymer is present in the polymer solution at a concentration of less than about 15% by weight. It should be understood that the at least one silicon-based polymer is present in solution, and therefore, a concentration of 0% in solution is not contemplated.

The polymer solution also comprises a primary solvent that is selected and incorporated in order to solvate the desirable higher molecular weight silicon-based polymers and at least one additional solvent that is selected and incorporated in order to solvate the undesirable lower molecular weight species that are responsible for forming defects in the final film or layer, such as the symmetrical cage structures previously mentioned. In contemplated embodiments, the addition of the at least one additional solvent in order to solvate the undesirable lower molecular weight species produces a film that, as compared to a conventional film, has lower defect counts. Lower defect counts can be determined in the following way. The conventional (reference) film formed without using at least one additional solvent to solvate or otherwise remove the undesirable lower molecular weight species will have a reference defect count. The film formed using the at least one additional solvent in order to solvate the undesirable lower molecular weight species produces a film that has a lower target defect count than the reference defect count in the reference film. This concept of a reference defect count and a lower target defect count is shown in the Examples presented herein. Suitable solvents for use in the polymer solution as either a primary solvent or an additional solvent include any suitable pure or mixture of organic, organometallic, or inorganic molecules that are volatized at a desired temperature. Suitable solvents include aprotic solvents, for example, cyclic ketones such as cyclopentanone, cyclohexanone, cycloheptanone, and cyclooctanone; cyclic amides such as N-alkylpyrrolidinone wherein the alkyl has from about 1 to 4 carbon atoms; and N-cyclohexylpyrrolidinone and mixtures thereof. A wide variety of other organic solvents may be used herein insofar as they effectively control the viscosity of the resulting solution as a coating solution. Various facilitating measures such as stirring and/or heating may be used to aid in the dissolution. Other suitable solvents include methyethylketone, methyHsobutylketone, dibutyl ether, cyclic dimethylpolysiloxanes, butyrolactone, γ-butyrolactone, 2-heptanone, ethyl 3- ethoxypropionate, polyethylene glycol dimethyl ether, propylene glycol methyl ether acetate (PGMEA), anisole, and hydrocarbon solvents such as mesitylene, xylenes, benzene, and toluene. A preferred solvent for the primary solvent is PGMEA and preferred additional solvents include γ-butyrolactone, dimethylacetamide, dimethylformamide, l-methyl-2- pyrrolidinone, epsilon-caprolactone, tetrahydrofuran, cyclopentanone, cyclohexanone, methylethylketone, methyHsobutylketone, acetonylacetone, γ-caprolactone, propylene carbonate, tetramethylene sulfone, as well as other polar, aprotic solvents. It is contemplated that the at least one primary solvent is added at a concentration of at least about 98% by weight in solution. In some contemplated embodiments, the at least one primary solvent is added at a concentration of at least about 80% by weight in solution. In other contemplated embodiments, the at least one primary solvent is added at a concentration of at least 60% by weight in solution. And in yet other contemplated embodiments, the at least one primary solvent is added at a concentration of at least 50% by weight in solution. The at least one additional solvent is contemplated to be added at a combined concentration of at least about 20% by weight in solution. In other embodiments, the at least one additional solvent is contemplated to be added at a combined concentration of at least about 15% by weight in solution. In yet other embodiments, the at least one additional solvent is contemplated to be added at a combined concentration of at least about 10% by weight in solution. In some other embodiments, the at least one additional solvent is contemplated to be added at a combined concentration of at least about 5% by weight in solution. It should be understood that there is at least some concentration of the at least one additional solvent in solution.

Some general examples of contemplated polymer solutions include:

> A silsesquioxane polymer in the concentration range of about 2% to about 5%, PGMEA in the concentration range of about 90% to about 95%, and propylene carbonate in the concentration range of about 2% to about 7%;

> A silsesquioxane polymer in the concentration range of about 2% to about 5%, PGMEA in the concentration range of about 85% to about 95%, and epsilon- ccaaprolactone in the concentration range of about 2% to about 13%;

> A silsesquioxane polymer in the concentration range of about 2% to about 5%, PGMEA in the concentration range of about 85% to about 95%, and l-methyl-2- pyrrolidinone in the concentration range of about 2% to about 13%.

In addition to manipulating the components of the polymer solution, several other steps may be taken to improve the polymer solution such that defects and discontinuities in the resulting film can be minimized or eliminated altogether. Some of these steps include: manipulating intensive properties, such as temperature and concentration, of the system prior to and during filtration steps, thereby causing some of the deleterious insolubles to be precipitated and removed from the system prior to coating.

The present organosiloxane composition may also comprise additional components such as adhesion promoters, antifoam agents, porogens, detergents, flame retardants, pigments, plasticizers, stabilizers, srriation modifiers, and surfactants, as discussed and disclosed in co-owned, issued and pending applications: US Patent Nos. 6225238 and 6395649; US Patent Application Nos.: 10/122400, 09/471299 and 10/163144; and PCT Serial No.: PCT/US02/36327, which are all incorporated herein in their entirety by reference.

Methods of producing a polymer solution comprise: a) providing at least one silicon- based polymer having high molecular weight species and low molecular weight species after solvation with a compatible primary solvent, wherein the low molecular weight species crystallize in or precipitate out of the polymer solution; b) providing a primary solvent that solvates the high molecular weight species in the solution; c) providing at least one additional solvent that solvates the low molecular weight species in the solution; and d) blending the at least one silicon-based polymer, the primary solvent and the at least one additional solvent to form the polymer solution. Methods of processing a polymer solution, such as those described herein, include: a) providing a filtration method or device, b) providing a polymer solution comprising high molecular weight species and low molecular weight species, wherein the low molecular weight species are in the form of crystals or precipitates, and c) utilizing the filtration method or device to filter the low molecular weight species out from the polymer solution. Contemplated filtration methods and devices include conventional filtration methods and devices, such as and/or including filters (such as those described in Example 3), membranes, chemicals, absorbent particles and combinations thereof.

APPLICATIONS The polymer solutions described herein may be used as an adhesion promoter in that it exhibits good adhesive properties when coupled with other materials in non-microelectronic or microelectronic applications. In microelectronic applications, the present composition may be coupled with conventional and not-so-conventional layered materials, such as nanoporous dielectrics, cage-based dielectric materials, anti-reflective coatings, photoresist materials, conformal dielectric materials, substrates, infiltration layers, coatings, and other layering or filling materials used for producing layered stacks, electronic components, or semiconductors.

The polymer solutions may be applied to various substrates to form layered materials, layers used in semiconductor processing, or layers used in electronic components, depending on the specific fabrication process by any conventional deposition process, including spin-on deposition techniques, rolling, dripping, dipping, plating and combinations thereof. Some contemplated techniques include a dispense spin, a thickness spin, and thermal bake steps, to produce an absorbing anti-reflective coating. Some typical processes include a thickness spin of between 1000 and 4000 rpm for about 20 seconds and one to three bake steps at temperatures between 80°C and 300°C for about one minute each. The coatings, according to the subject matter herein exhibit refractive indices between about 1.3 and about 2.0 and extinction coefficients greater than approximately 0.07. As used herein, the phrases "spin-on material", "spin-on composition", "spin-on polymer solution" and "spin-on inorganic composition" may be used interchangeable and refer to those solutions and compositions that can be spun-on to a substrate or surface. It is further contemplated that the phrase "spin-on-glass materials" refers to a subset of "spin-on inorganic materials", in that spin-on glass materials refer to those spin-on materials that comprise silicon-based compounds andor polymers in whole or in part.

Substrates contemplated herein may comprise any desirable substantially solid material. Particularly desirable substrate layers would comprise films, glass, ceramic, plastic, metal or coated metal, or composite material. In preferred embodiments, the substrate comprises a silicon or germanium arsenide die or wafer surface, a packaging surface such as found in a copper, silver, nickel or gold plated leadframe, a copper surface such as found in a circuit board or package interconnect trace, a via-wall or stiffener interface ("copper" includes considerations of bare copper and its oxides), a polymer-based packaging or board interface such as found in a polyimide-based flex package, lead or other metal alloy solder ball surface, glass and polymers such as polyimide. In more preferred embodiments, the substrate comprises a material common in the packaging and circuit board industries such as silicon, copper, glass, and another polymer.

Contemplated polymer materials, coating solutions and films can be utilized are useful in the fabrication of a variety of electronic devices, micro-electronic devices, particularly semiconductor integrated circuits and various layered materials for electronic and semiconductor components, including hardmask layers, dielectric layers, etch stop layers and buried etch stop layers. These polymer materials, coating solutions and films are quite compatible with other materials that might be used for layered materials and devices, such as adamantane-based compounds, diamantane-based compounds, silicon-core compounds, organic dielectrics, and nanoporous dielectrics. Compounds that are considerably compatible with the coating materials, coating solutions and films contemplated herein are disclosed in PCT Application PCT/US01/32569 filed October 17, 2001; PCT Application PCT/US01/50812 filed December 31, 2001; US Application Serial No. 09/538276; US Application Serial No. 09/544504; US Application Serial No. 09/587851; US Patent 6,214,746; US Patent 6,171,687; US Patent 6,172,128; US Patent 6,156,812, US Application Serial No. 60/350187 filed January 15, 2002; and US 60/347195 filed January 8, 2002, which are all incorporated herein by reference in their entirety.

The compounds, coatings, films, materials and the like described herein may be used to become a part of, form part of or form an electronic component and/or semiconductor component. As used herein, the terra "electronic component" also means any device or part that can be used in a circuit to obtain some desired electrical action. Electronic components contemplated herein may be classified in many different ways, including classification into active components and passive components. Active components are electronic components capable of some dynamic function, such as amplification, oscillation, or signal control, which usually requires a power source for its operation. Examples are bipolar transistors, field- effect transistors, and integrated circuits. Passive components are electronic components that are static in operation, i.e., are ordinarily incapable of amplification or oscillation, and usually require no power for their characteristic operation. Examples are conventional resistors, capacitors, inductors, diodes, rectifiers and fuses. Electronic components contemplated herein may also be classified as conductors, semiconductors, or insulators. Here, conductors are components that allow charge carriers (such as electrons) to move with ease among atoms as in an electric current. Examples of conductor components are circuit traces and vias comprising metals. Insulators are components where the function is substantially related to the ability of a material to be extremely resistant to conduction of current, such as a material employed to electrically separate other components, while semiconductors are components having a function that is substantially related to the ability of a material to conduct current with a natural resistivity between conductors and insulators. Examples of semiconductor components are transistors, diodes, some lasers, rectifiers, thyristors and photosensors. Electronic components contemplated herein may also be classified as power sources or power consumers. Power source components are typically used to power other components, and include batteries, capacitors, coils, and fuel cells. Power consuming components include resistors, transistors, integrated circuits (ICs), sensors, and the like.

Still further, electronic components contemplated herein may also be classified as discreet or integrated. Discreet components are devices that offer one particular electrical property concentrated at one place in a circuit. Examples are resistors, capacitors, diodes, and transistors. Integrated components are combinations of components that that can provide multiple electrical properties at one place in a circuit. Examples are integrated circuits in which multiple components and connecting traces are combined to perform multiple or complex functions such as logic. Preferably, the present compositions are used in microelectronic applications as etch stops, hardmasks, and dielectrics. Layers or films of the instant compositions may be formed by solution techniques such as spraying, rolling, dipping, spin coating, flow coating, chemical vapor deposition (CVD), or casting, with spin coating being preferred for microelectronics.

For chemical vapor deposition (CVD), the composition is placed into an CVD apparatus, vaporized, and introduced into a deposition chamber containing the substrate to be coated. Vaporization may be accomplished by heating the composition above its vaporization point, by the use of vacuum, or by a combination of the above. Generally, vaporization is accomplished at temperatures in the range of 50°C-300°C under atmospheric pressure or at lower temperature (near room temperature) under vacuum. Three types of CVD processes exist: atmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), and plasma enhanced CVD (PECVD). Each of these approaches had advantages and disadvantages. APCVD devices operate in a mass transport limited reaction mode at temperatures of approximately 400 °C. In mass-transport limited deposition, temperature control of the deposition chamber is less critical than in other methods because mass transport processes are only weakly dependent on temperature. As the arrival rate of the reactants is directly proportional to their concentration in the bulk gas, maintaining a homogeneous concentration of reactants in the bulk gas adjacent to the wafers is critical. Thus, to insure films of uniform thickness across a wafer, reactors that are operated in the mass transport limited regime must be designed so that all wafer surfaces are supplied with an equal flux of reactant. The most widely used APCVD reactor designs provide a uniform supply of reactants by horizontally positioning the wafers and moving them under a gas stream.

In contrast to APCVD reactors, LPCVD reactors operate in a reaction rate-limited mode. In processes that are run under reaction rate-limited conditions, the temperature of the process is an important parameter. To maintain a uniform deposition rate throughout a reactor, the reactor temperature must be homogeneous throughout the reactor and at all wafer surfaces. Under reaction rate-limited conditions, the rate at which the deposited species arrive at the surface is not as critical as constant temperature. Thus, LPCVD reactors do not have to be designed to supply an invariant flux of reactants to all locations of a wafer surface.

Under the low pressure of an LPCVD reactor, for example, operating at medium vacuum (30-250 Pa or 0.25-2.0 ton) and higher temperature (550-600°C), the diffusivity of the deposited species is increased by a factor of approximately 1000 over the diffusivity at atmospheric pressure. The increased diffusivity is partially offset by the fact that the distance across which the reactants must diffusive increases by less than the square root of the pressure. The net effect is that there is more than an order of magnitude increase in the transport of reactants to the substrate surface and by-products away from the substrate surface.

LPCVD reactors are designed in two primary configurations: (a) horizontal tube reactors; and (b) vertical flow isothermal reactors. Horizontal tube, hot wall reactors are the most widely used LPCVD reactors in VLSI processing. They are employed for depositing poly-Si, silicon nitride, and undoped and doped Si0₂ films. They find such broad applicability primarily because of their superior economy, throughput, uniformity, and ability to accommodate large diameter, e.g., 150 mm, wafers.

The vertical flow isothermal LPCVD reactor further extends the distributed gas feed technique so that each wafer receives an identical supply of fresh reactants. Wafers are again stacked side by side, but are placed in perforated-quartz cages. The cages are positioned beneath long, perforated, quartz reaction-gas injector tubes, one tube for each reactant gas. Gas flows vertically from the injector tubes, through the cage perforations, past the wafers, parallel to the wafer surface and into exhaust slots below the cage. The size, number, and location of cage perforations are used to control the flow of reactant gases to the wafer surfaces. By properly optimizing cage perforation design, each wafer may be supplied with identical quantities of fresh reactants from the vertically adjacent injector tubes. Thus, this design may avoid the wafer-to-wafer reactant depletion effects of the end-feed tube reactors, requires no temperature ramping, produces highly uniform depositions, and reportedly achieves low particulate contamination. The third major CVD deposition method is PECVD. This method is categorized not only by pressure regime, but also by its method of energy input. Rather than relying solely on thermal energy to initiate and sustain chemical reactions, PECVD uses an rf-induced glow discharge to transfer energy into the reactant gases, allowing the substrate to remain at a lower temperature than in APCVD or LPCVD processes. Lower substrate temperature is the major advantages of PECVD, providing film deposition on substrates not having sufficient thermal stability to accept coating by other methods. PECVD may also enhance deposition rates over those achieved using thermal reactions. Moreover, PECVD may produce films having unique compositions and properties. Desirable properties such as good adhesion, low pinpole density, good step coverage, adequate electrical properties, and compatibility with fine-line pattern transfer processes, have led to application of these films in VLSI. PECVD requires control and optimization of several deposition parameters, including

RF power density, frequency, and duty cycle. The deposition process is dependent in a complex and interdependent way on these parameters, as well as on the usual parameters of gas composition, flow rates, temperature, and pressure. Furthermore, as with LPCVD, the PECVD method is surface reaction limited, and adequate substrate temperature control is thus necessary to ensure uniform film thickness.

CVD systems usually contain the following components: gas sources, gas feed lines, mass-flow controllers for metering the gases into the system, a reaction chamber or reactor, a method for heating the wafers onto which the film is to be deposited, and in some types of systems, for adding additional energy by other means, and temperature sensors. LPCVD and PECVD systems also contain pumps for establishing the reduced pressure and exhausting the gases from the chamber.

The present composition may be used as an interlayer dielectric in an interconnect associated with a single integrated circuit ("IC") chip. An integrated circuit chip would typically have on its surface a plurality of layers of the instant composition and multiple layers of metal conductors. It may also include regions of the present composition between discrete metal conductors or regions of conductor in the same layer or level of an integrated circuit.

In application of the instant polymers to ICs, a solution of the present composition is applied to a semiconductor wafer using conventional wet coating processes as, for example, spin coating; other well known coating techniques such as spray coating, flow coating, or dip coating may be employed in specific cases. In the spin coating process, the organosiloxane resin solution prepared in the manner described above is dispensed onto a wafer at or near its center. In some embodiments, the wafer will remain stationary during the dispense cycle, while in some embodiments, the wafer will turn or spin at a relatively low speed, typically at least about 200 revolutions per minute (rpm). Optionally, the dispense cycle may be followed by a short rest period and then additional spins, hereinafter referred to as thickness spins, generally between approximately 500 and 3000 rpm, although other spin speeds may be used, as appropriate. As an illustration, a cyclohexanone solution of the present composition is spin-coated onto a substrate having electrically conductive components fabricated therein and the coated substrate is then subjected to thermal processing. The present composition may be used in substractive metal (such as aluminum and aluminum/tungsten) processing and dual damascene (such as copper) processing. An exemplary formulation of the instant composition is prepared by dissolving the present composition in cyclohexanone solvent under ambient conditions with strict adherence to a clean-handling protocol to prevent trace metal contamination in any conventional apparatus having a non-metallic lining. An illustration of the use of the polymer solutions described herein follows.

Application of the instant compositions and casting solutions onto planar or topographical surfaces or substrates may be carried out by using any conventional apparatus, preferably a spin coater, because the compositions used herein have a controlled viscosity suitable for such a coater. Complete evaporation of the solvent by any suitable means, such as simple air drying during spin coating, by exposure to an ambient environment, or by heating on a hot plate or a plurality of hot plates up to 350°C, may be employed. The substrate may have on it at least one layer of the present composition. Further curing may be achieved by a hot temperature, i.e, greater than 300°C, hot plate or furnace. In addition to furnace or hot plate curing, the present compositions may also be cured by exposure to ultraviolet radiation, microwave radiation, or electron beam radiation as taught by commonly assigned patent publication PCT/US96/08678; PCT/US00/28689 (WO 01/29052); and PCT/US00/28738 (WO 01/29141); and U.S. Pat. Nos. 6,042,994; 6,080,526; 6,177,143; and 6,235,353, which are incorporated herein by reference in their entireties. The present compositions may also be subjected to ultraviolet radiation, microwave radiation, or electron beam radiation to achieve certain desirable film properties. After application of the present composition to an electronic topographical substrate, the coated structure is subjected to a bake and cure thermal process at increasing temperatures ranging from about 50°C. up to about 450°C to polymerize the coating. The preferred curing temperature is at least about 150°C. Generally, it is preferred that curing is carried out at temperatures of from about 350°C to about 425°C. Curing may be carried out in a conventional curing chamber such as an electric furnace, hot plate, and the like and is generally performed in an inert (non-oxidizing) atmosphere (nitrogen) in the curing chamber. Any non-oxidizing or reducing atmospheres (eg. argon, helium, hydrogen, and nitrogen processing gases) may he used in the practice of the present invention. One advantage of the present composition is that it has minimal weight loss during curing.

As indicated earlier, the present coating may act as an interlayer and be on top of or covered by other organic or inorganic coatings, such as other dielectric (Si0₂) coatings, Si0₂ modified ceramic oxide layers, silicon containing coatings, silicon carbon containing coatings, silicon nitrogen containing coatings, silicon-nitrogen-carbon containing coatings, diamond like carbon coatings, titanium nitride coatings, tantalum nitride coatings, tungsten nitride coatings, aluminum coatings, copper coatings, tantalum coatings, organosiloxanes coatings, organosilicon glass coatings, and fluorinated silicon glass coatings. Such multilayer coatings are taught in U.S. Pat. No. 4,973,526, which is incorporated herein by reference. And, as amply demonstrated, the present compositions prepared in the instant process may be readily formed as interlined dielectric layers between adjacent conductor paths on fabricated electronic or semiconductor substrates.

A semiconductor device comprising a film of the present composition typically has a second film adjacent to the first film. This second film may be an inorganic or organic material, A preferred organic material is an aromatic or aliphatic hydrocarbon and more preferably, an adamantane or diamantane based material is used. Examples of useful materials for the second film include but are not limited to those disclosed in International Publication

WO00/31183 published Jun. 2, 2000 and our pending patent applications Serial

PCT/US01/22204 filed Oct. 17, 2001; PCT/US01/50182 filed Dec. 31, 2001; No. 60/345,374 filed Dec. 31, 2001; No. 60/347,195 filed Jan. 8, 2002; No. 60/350,187 filed Jan. 15, 2002; commonly assigned U.S. Pat. Nos. 6,126,733; 5,115,082; 5,986,045; and 6,143,855; and commonly assigned International Patent Publications WO02/29052 published Apr. 26, 2001; and WO01/29141 published Apr. 26, 2001.

The present composition has a dielectric constant of less than about 3.2 and in other contemplated embodiments, the. dielectric constant is less than about 2.8.

The present composition may be used in a desirable all spin-on stacked film as taught by Michael E. Thomas, "Spin-On Stacked Films for Low k_etr Dielectrics", Solid State Technology (July 2001), incorporated herein in its entirety by reference.

EXAMPLES

ANALYTICAL TEST METHODS:

DIELECTRIC CONSTANT: The dielectric constant was determined by coating a thin film of aluminum on the cured layer and then doing a capacitance-voltage measurement at 1 MHz and calculating the k value based on the layer thickness.

SHRINKAGE/EXPANSION: Film shrinkage or expansion was measured by determining the film thickness before and after the process. Shrinkage was expressed in percent of the original film thickness. Shrinkage was positive if the film thickness decreased. The actual thickness measurements were performed optically using a J. A. Woollam M-88 spectroscopic ellipsometer. A Cauchy model was used to calculate the best fit for Psi and Delta (details on Ellipsometry can be found in e.g. "Spectroscopic Ellipsometry and Reflectometry" by H. G. Thompkins and William A. McGahan, John Wiley and Sons, Inc., 1999).

REFRACTIVE INDEX: The refractive index measurements were performed together with the thickness measurements using a J. A. Woollam M-88 spectroscopic ellipsometer. A Cauchy model was used to calculate the best fit for Psi and Delta. Unless noted otherwise, the refractive index was reported at a wavelenth of 633 nm (details on Ellipsometry can be found in e.g. "Spectroscopic Ellipsometry and Reflectometry" by H. G. Thompkins and William A. McGahan, John Wiley and Sons, Inc., 1999).

FTIR ANALYSIS: FTIR spectra were taken using a Nicolet Magna 550 FTIR spectrometer in transmission mode. Substrate background spectra were taken on uncoated substrates. Film spectra were taken using the substrate as background. Film spectra were then analyzed for change in peak location and intensity. The results are reported in an absorbance mode.

ISOTHERMAL GRAVIMETRIC ANALYSIS (ITGA) WEIGHT Loss: Total weight loss was determined on the TA Instruments 2950 Thermogravimetric Analyzer (TGA) used in conjunction with a TA Instruments thermal analysis controller and associated software. A Platinel II Thermocouple and a Standard Furnace with a temperature range of 25°C to 1000 °C and heating rate of 0.1 °C to 100 °C /min were used. A small amount of sample (7 to 12 mg) was weighed on the TGA's balance (resolution: 0.1 .mu.g; accuracy: to .+-.0.1%) and heated on a platinum pan. Samples were heated under nitrogen with a purge rate of 100 ml min (60 ml min going to the furnace and 40 ml/min to the balance).

TAPE TEST: The tape test was performed following the guidelines given in ASTM D3359-95. A grid was scribed into the dielectric layer according to the following. A tape test was performed across the grid marking in the following manner: (1) a piece of adhesive tape, preferably Scotch brand #3 m600-l/2X1296, was placed on the present layer, and pressed down firmly to make good contact; and (2) the tape was then pulled off rapidly and evenly at an angle of 180° to the layer surface. The sample was considered to pass if the layer remained intact on the wafer, or to have failed if part or all of the film pulled up with the tape.

PARTICLE COUNT: Film particles counts were measured on a KLA 6420 Surfscan. An oxide recipe with a film thickness matching the product film thickness was used. The recipe was set up with the lowest size threshold to be 0.2 microns. The particle number reported is the total number of particles detected above the size threshold.

CANDELA FILM: Wafers were analyzed with a Candela OS A and spun at 5000 rpm for the measurements. The data was acquired using S-specular acquisition mode with 50 microns track spacing and 16K data points per track. The resulting images were inspected visually for defects. No quantitative analysis was performed.

CONTACT ANGLE: The contact angle measurement was performed to determine the contact angle of the dielectric solution on the inventive product in order to create a Si- wafer/dielectric/inventive product/dielectric stack. A VCA2500 Video Contact Angle System from ASC Products was used to perform the measurements. In preparation for the measurement, the wafer was coated with the first dielectric layer and then the inventive product layer. For the measurement, a droplet of the dielectric solution which was to be deposited as the top layer was brought in contact with the inventive product surface. The droplet volume was set to 0.8 microliter. The video image was captured for the next 3.5 seconds beginning with time when the droplet was formed on the surface. The contact angle was then measured on the captured video image using the contact angle measurement software. The average of five measurements is reported. The Examples from US Patent Application Publication No. 2003/0031789 Al are incorporated herein in their entirety to show polymer solutions that are considered conventional solutions for the purposes of the subject matter herein.

EXAMPLE 1

Coating defects in films and layers are attributable to part of the polymer molecular weight distribution, including the low molecular weight species previously described herein. It is herein discovered that low M_w and M_n polymers have higher levels of defects than high M_w and M_n. Table 1 shows the results of the molecular weight fractionation experiments.

The lower molecular weight fractions are known to have very regular cage structures and are also known to have limited solubility. We can minimize the precipitation and/or crystallization of the low molecular weight fractions (which are directly responsible ^■ for forming defects) by improving their solubility, as previously described. Solvents which have been tested in this regard include NMP, THF, e-caprolactone, PGMEA, toluene, propylene carbonate, GBL, sulfolane, dimethyl acetamide and dimethyl formamide. Tables 2-5 show the results of these additional solvents on the solvation of the low molecular weight species. As shown, NMP showed the lowest defect levels and reduced defects by at least 350 times from the control containing only PGMEA as the primary solvent. GBL decreased defect levels by at least 40 times in a 250 Angstrom sample layer as compared to the control containing only PGMEA as the primary solvent. (Both shown in Table 2) Propylene carbonate and e-caprolactone show comparable defect levels to GBL and are about 10-30% higher than in the NMP case. (Shown in Tables 3 and 4). Table 5 shows a summary of the results found in Tables 2 and 4.

EXAMPLE 2:

This example demonstrates the simulated effect of molecular weight and functional group distribution on the solubility of a silicon-based formulation, such as HOSP-BEST, by calculation of the expected solubility parameter trends (Figure 1). Starting from the the monomer distribution (lowest end of the MW range in the HOSP random structure), the solubility parameters are very high. Typical solvent solubility parameters are also very high in comparison to HOSP-BEST (Table 6). Polymerization causes a drop in solubility parameter away from typical solvents, but typically will stabilize, as demonstrated in the MW region >4000.

According to the calculated solubility parameters, the solubilities of an oligomeric piece will be influenced by the MW, the amount of organic content exposed to solvent and the type of organic content. For instance, an all hydride construction appears to drop in solubility parameter faster with MW increase than other content, and an all phenyl construction appears to maintain higher solubility parameter. In addition, an all phenyl construction is much higher in solubility parameter than the other oligomers, and if the lower MW species is formed it may be incompatible with other stoichiometrical mixes of higher MW formed during the synthesis. Also, it appears that there might be a lower MW region in which the HOSP-BEST random oligomer becomes more insoluble than either the higher or lower MW fractions.

Because of these differences and because of reactivity differences that might shift this insoluble region, it is apparent that an improvement in formulation might come directly from refinement of the MW fractions used in the actual formulation in practice. In particular definition and elimination of the specific insoluble low MW fraction produced during synthesis is crucial in obtaining formulations with low particle defect count in the film. Table 6 Solvent Solubility Parameters of Typical Solvents (j/cc)' 0.5

Total Electrostatic VDW pgmea 21.41 6.94 20.26 ethyl 3-ethoxypropionate (eep) 19.54 5.10 18.84 heptanone 17.85 5.26 17.06

Et Lactate 24.28 12.70 20.69

NMP 24.10 10.06 21.90 propylene carbonate 26.10 11.87 23.25 butyrolactone 24.96 10.80 22.50 anisole 26.14 4.77 25.70 cyclopentanone 21.17 5.98 20.30 ethylacetoacetate 22.02 8.02 20.50

EXAMPLE 3:

Coating defects in films and layers are attributable to part of the polymer molecular weight distribution, including the low molecular weight species previously described herein. Removing low moleculaτ weight species by means of standard filtration processes, using filters with pore sizes greater or equal than 0.1 μm is not feasible. Special filter products with membrane pore sizes much smaller than 0.1 μm are necessary to obtain low detectivity films. Table 7 below shows the results of filtration experiments.

Thus, specific embodiments and applications of compositions and methods to minimize coating defects for compositions comprising siloxane-based compounds and methods thereof have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the disclosure herein. Moreover, in interpreting the disclosure of the subject matter, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms "comprises" and "comprising" should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.

Table 2

Table 3

Table 4

Table 5

Claims

CLAIMSWe claim:

1. A polymer solution, comprising: at least one silicon-based polymer having high molecular weight species and low molecular weight species after solvation with a compatible primary solvent, wherein the low molecular weight species crystallize in or precipitate out of the polymer solution; a primary solvent that solvates the high molecular weight species in the solution; and at least one additional solvent that solvates the low molecular weight species in the solution.

2. The polymer solution of claim 1, wherein the at least one silicon-based polymer comprises a siloxane compound.

3. The polymer solution of claim 1 , wherein the at least one silicon-based comprises a polymer having the formula: [Y_θ.0₁-_l._θSiO_l.₅-₂]_a[Zθ.0₁-_l._θSiO_l.s_-2]_b[Ho.0₁-_l._θSiOι.₅.₂]_c where Y is aryl; Z is alkenyl; a is from 15 percent to 70 percent of Formula 5; b is from 2 percent to 50 percent of Formula 5; and c is from 20 percent to 80 percent of Formula 5; and

4. The polymer solution of claim 1 , wherein the at least one silicon-based polymer is present in solution at a weight percent of less than about 25%.

5. The polymer solution of claim 4, wherein the at least one silicon-based polymer is present in solution at a weight percent of less than about 20%.

6. The polymer solution of claim 5, wherein the at least one silicon-based polymer is present in the solution at a weight percent of less than about 15%.

7. The polymer solution of claim 1 , wherein the primary solvent comprises propylene glycol methyl ether acetate

8. The polymer solution of claim 1 , wherein the primary solvent is present in the solution at a weight percent of at least about 98%.

9. The polymer solution of claim 8, wherein the primary solvent is present in the solution at a weight percent of at least about 80%.

10. The polymer solution of claim 9, wherein the primary solvent is present in the solution at a weight percent of at least about 50%.

11. The polymer solution of claim 1 , wherein the at least one additional solvent comprises at least one polar, aprotic solvent.

12. The polymer solution of claim 1, wherein the at least one additional solvent comprises γ-butyrolactone, dimethylacetamide, dimethylformamide, l-methyl-2-pyrrolidinone, epsilon-caprolactone, tetrahydrofuran, cyclopentanone, cyclohexanone, methylethylketone, methyHsobutylketone, acetonylacetone, γ-caprolactone, propylene carbonate, tetramethylene sulfone, as well as combinations thereof.

13. A layer comprising the polymer solution of claim 1.

14. A film formed from the polymer solution of claim 1.

15. A solvent solution that solvates a silicon-based polymer having high molecular weight species and low molecular weight species after solvation with a compatible primary solvent, wherein the low molecular weight species crystallize in or precipitate out of the polymer solution, comprising: a primary solvent that solvates the high molecular weight species in the solution; and at least one additional solvent that solvates the low molecular weight species in the solution.

16. A method of producing a polymer solution, comprising: providing at least one silicon-based polymer having high molecular weight species and low molecular weight species after solvation with a compatible primary solvent, wherein the low molecular weight species crystallize in or precipitate out of the polymer solution; providing a primary solvent that solvates the high molecular weight species in the solution; providing at least one additional solvent that solvates the low molecular weight species in the solution; and blending the at least one silicon-based polymer, the primary solvent and the at least one additional solvent to form the polymer solution.

17. The method of claim 16, wherein the at least one silicon-based polymer comprises a siloxane compound.

18. The method of claim 16, wherein the at least one silicon-based comprises a polymer having the formula:

[Yθ.01-l.θSiOl.5-2]a[Zo.01-l.θSiOι.5-2]b[Ho.01-l.θSiOl.5-2]c where Y is aryl; Z is alkenyl; a is from 15 percent to 70 percent of Formula 5; b is from 2 percent to 50 percent of Formula 5; and c is from 20 percent to 80 percent of Formula 5; and

19. The method of claim 16, wherein the at least one silicon-based polymer is present in solution at a weight percent of less than about 25%.

20. The method of claim 19, wherein the at least one silicon-based polymer is present in solution at a weight percent of less than about 20%.

21. The method of claim 20, wherein the at least one silicon-based polymer is present in the solution at a weight percent of less than about 15%.

22. The method of claim 16, wherein the primary solvent comprises propylene glycol methyl ether acetate

23. The method of claim 16, wherein the primary solvent is present in the solution at a weight percent of at least about 98%.

24. The method of claim 23, wherein the primary solvent is present in the solution at a weight percent of at least about 80%.

25. The method of claim 24, wherein the primary solvent is present in the solution at a weight percent of at least about 50%.

26. The method of claim 16, wherein the at least one additional solvent comprises at least one polar, aprotic solvent.

27. The method of claim 16, wherein the at least one additional solvent comprises γ- butyrolactone, dimethylacetamide, dimethylformamide, l-methyl-2-pyrrolidinone, epsilon-caprolactone, tetrahydrofuran, cyclopentanone, cyclohexanone, methylethylketone, methyHsobutylketone, acetonylacetone, γ-caprolactone, propylene carbonate, tetramethylene sulfone, as well as combinations thereof.

28. A dielectric layer comprising the film of claim 14.

29. A microelectronic application comprising the dielectric layer of claim 28.

30. The film of claim 14, wherein the film comprises a low particle defect count as compared to a reference film.

31. A method of processing a polymer solution, comprising: providing a filtration method or device, providing a polymer solution comprising high molecular weight species and low molecular weight species, wherein the low molecular weight species are in the form of crystals or precipitates, and utilizing the filtration method or device to filter the low molecular weight species out from the polymer solution.

32. The method of claim 31, wherein the polymer solution comprises a silicon-based composition.

33. The method of claim 32, wherein the at least one silicon-based polymer comprises a siloxane compound.

34. The method of claim 32, wherein the at least one silicon-based comprises a polymer having the formula: [Y_θ.₀1-I._θSiOl.5-2]a[Zo.01-_l._θSiOl.5-2]b[Ho.₀1-l._θSiOl.5_-2]_c where Y is aryl; Z is alkenyl; a is from 15 percent to 70 percent of Formula 5; b is from 2 percent to 50 percent of Formula 5; and c is from 20 percent to 80 percent of Formula 5; and

35. The method of claim 32, wherein the at least one silicon-based polymer is present in solution at a weight percent of less than about 25%.

36. The method of claim 35, wherein the at least one silicon-based polymer is present in solution at a weight percent of less than about 20%.

37. The method of claim 36, wherein the at least one silicon-based polymer is present in the solution at a weight percent of less than about 15%.

38. A polymer solution produced by the method of claim 31.

39. A film formed using the polymer solution of claim 38.

40. The film of claim 39, wherein the film comprises a low particle defect count as compared to a reference film.