KR20000033206A - Method for forming low permittivity film utilizing vapor silylation process - Google Patents

Abstract

PURPOSE: A method for forming a low permission film is provided to prevent a low permission material from reacting with moisture, and to prevent remained silylation agents from activating. CONSTITUTION: A layer of low permission material(30) of a hydroxy terminal group is formed. Next, steam of silylation agents is injected into a chamber, so that the layer of low perceptivity material(30) is silylated. Thus, the silylation can be performed without an acid catalyzer. Also, the process is performed in vacuum condition. Thereby, low permission material can be prevented from reacting with moisture, and the remained silylation agents can be prevented from activating.

Description

Low dielectric film formation method using vapor phase silicification process.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for manufacturing a low dielectric thin film used for the purpose of insulation between metal wirings, insulation between metal wiring layers, etc. during a semiconductor device manufacturing process using a vapor phase siliculation process.

In the latter process of semiconductor device manufacturing, the insulating film growth technique is used for the purpose of insulation between metal wirings, insulation between metal wiring layers, and the like. However, with the trend of continuous integration of semiconductor devices, the number and density of wirings in subsequent processes of logic and memory devices are increasing, and the spacing between metal wirings is gradually decreasing. Silicon dioxide (SiO ₂ ), which is currently used as an insulating material, has a dielectric constant (k) of about 4.0, and at an integration degree of 0.25 μm or less, parasitic capacitance rapidly increases as the distance between wirings decreases. For this reason, in terms of device response speed, signal interference, and power consumption, conventional insulating materials are no longer capable of improving device characteristics. In order to overcome this problem, design improvements such as reducing the length of the wiring layer and increasing the thickness of the insulating layer have been made. However, some approaches have been pointed out as obstacles to the improvement of device performance in a manner contrary to the trend of integration.

Accordingly, various attempts have been made to introduce copper into a metal wiring material which has a lower resistivity than aluminum and a dielectric material having a low dielectric constant (K < 3.0). In particular, in the case of a logic device having a complicated number of wiring layers and a structure, a serious deterioration of the characteristics of a conventional device is required, and the necessity of introducing a low dielectric constant insulating material is increasing.

The insulating material used in the semiconductor process must satisfy characteristics such as excellent electrical insulation, sufficient mechanical strength, low residual stress, high adhesion, high thermal conductivity, and smooth flatness. However, since the conventional low dielectric constant material is a soft material in nature, it is generally inferior to an oxide film having high thermal, structural and chemical properties. Therefore, various kinds of materials have been developed for the selection of low dielectric constant materials suitable for metal wiring processes. In particular, inorganic materials include silsesquioxane, amorphous carbon fluoride (CF _x ), phosphorus silicates, and organic materials such as parylenes and polyarylene ethers. ethers, polyimides, cyclobutene derivatives, etc. have been developed and some materials have been applied to the actual process.

In general, the inorganic materials listed above are known to be fairly stable even at high temperatures of 500 ° C. or higher and have excellent mechanical strength. However, the inorganic materials are very sensitive to moisture in the process and difficult to coat on the metallization layer below 1 μm. On the other hand, it is known that the above organic materials can be coated with a thickness of 1 μm or less and are suitable for insulation of metal wiring layers with a dielectric constant of about 2.3 to 3.0.

In addition, attempts have been made to chemically introduce inorganic materials into organic materials for the purpose of improving thermal stability, which is a disadvantage of organic materials. However, such research has yet to be studied because it is difficult to obtain a stable chemical structure through chemical reaction between organic and inorganic materials.

It is known that a material having a low dielectric constant of about 2.9 is required when the transistor gate length is 0.25 μm. As a material having such a low dielectric constant and thermal, mechanical and chemical properties suitable for the process, a polyarylene ether system is known to be suitable. . The chemical structure and manufacturing method of the polyarylene ether are shown in the following Chemical Formula 1 and Scheme 1 and improve the dielectric constant and heat resistance characteristics by changing the substituent (X) intervening in various forms or by adding a fluorine (F) group Many attempts have been made, but do not deviate significantly from basic structures such as formula (I).

N is an integer equal to 0 or 1,

X is , or ego,

Y is a halogen element.

As such, low dielectric constant materials such as polyarylene ethers, which are generally used as spin coating methods on metal wiring layers, are composed of rigid groups such as benzene rings to promote thermal stability. There is a problem that the hydroxyl group (OH) remains as a terminal group to generate water (H ₂ O) to induce moisture to the low dielectric constant material. The influx of moisture into the low dielectric constant material increases the dielectric constant and causes a rapid decrease in thermal stability by lowering the glass transition temperature of the dielectric material. In order to solve this problem, the sensitivity to moisture can be reduced by reacting a silicon-containing material having a hydrophobic group with a hydroxy end group.

Therefore, polysilylene ether-based materials containing silicon having a basic structure such as the following Chemical Formula 2 may be prepared by silylation of a compound having a basic structure of Chemical Formula 1.

N is an integer equal to 0 or 1,

X is , or ego,

Y is a halogen element.

In general, the method for preparing the compound having the basic structure of Chemical Formula 2 is carried out in a liquid phase reaction according to a chemical production method, in which an acid catalyst is required for the reaction of the silylation agent and the polyarylene ether compound. The material needs a cosolvent that can dissolve at the same time. However, even if the liquid phase sillation reaction proceeds in the co-solvent, it is difficult to completely remove the unreacted silylation agent. These unreacted silylation agents will evaporate into the gas during the bake or cure process in the coated low dielectric constant material layer. At this time, the gas generated by evaporation forms a space in the low dielectric constant material layer. The creation of these spaces causes the problem of cracking or peeling off of the low dielectric constant material layer due to the stresses generated by subsequent processes repeated at high temperatures, in which there is a problem that other phases in the space or metal layer are formed.

Therefore, the technical problem to be achieved by the present invention is to introduce a hydrophobic group into a hydroxy terminal of an organic low dielectric constant material used as an insulating material between metal layers in a semiconductor manufacturing process by using a vapor phase silicidation method in a predetermined chamber. The present invention provides a method for forming a low dielectric film using a vapor phase silicide process in which a material is not sensitive to moisture and a residual silicide agent does not affect subsequent processes.

1 to 4 are cross-sectional views illustrating a method of forming a low dielectric thin film of a semiconductor device according to an embodiment of the present invention.

* Explanation of Codes on Major Parts of Drawings *

10 silicon substrate 20 metal wiring layer

30: low dielectric constant material layer having hydroxy end groups

35: low dielectric constant material layer having silicon end groups

In order to achieve the above technical problem, a method of forming a low dielectric film according to the present invention may include forming a low dielectric constant material layer having a hydroxyl terminal; And a gas phase sillation step of silencing the low dielectric constant material layer by introducing a vapor of the silylation agent into the chamber.

In addition, in order to achieve the above technical problem, the low dielectric film forming method according to the present invention has a low structure of a polyarylene ether base structure having a hydroxy terminal or a benzene group substituted with one or more fluoro groups thereof. Forming a dielectric material layer; A thin film of a polyarylene ether compound having a basic structure of Formula 2 or a benzene group substituted with one or more fluoro groups, and having a terminal group of trimethylsilane Characterized in that it comprises a step of forming.

In the method of forming a low dielectric constant thin film using the gas phase silylation according to the present invention, a method of forming a polyarylene ether-based low dielectric material layer may be obtained by using a polyarylene ether derivative having a basic structure of Formula 1 or substituted with a fluoro group. Or synthetically obtained was dissolved in 1 to 30% by weight in a solvent such as cyclopentanone, n-methyl pyrrolidine, dimethylacetamide or dimethylformamide, spin-coated on a wafer, and then at 150 to 250 ° C. It is preferable to form by baking to remove the solvent.

At this time, the coating thickness is preferably 1,000 to 10,000 kPa, and the baking time is preferably 20 to 300 seconds.

In the low dielectric constant thin film formation method using the gas phase silylation according to the present invention, the gas phase silylation method includes a polyarylene ether-based silicide agent vaporized at 50 to 250 ° C by placing a wafer having a low dielectric constant material layer in a vacuum chamber. Resilient by reacting with low dielectric constant materials.

Silylation agents that can be used to form low dielectric constant thin films according to the present invention include hexamethyl disilazane, tetramethyl disilazane, bisdimethylamino dimethylsilane, bisdiethylamino methylsilane, dimethylsilyl dimethylamine, dimethylsilyl diethyl Silylation agents generally used for silication can be used, such as amines, trimethylsilyl dimethylamine, trimethylsilyl diethylamine, or dimethylamino pentamethyldisilane and the like.

In addition, in the low dielectric constant thin film formation method according to the present invention, it is preferable to perform the vapor phase silicide for 30 to 300 seconds in consideration of the overall efficiency of the semiconductor device manufacturing process while allowing the silicide to be completely made.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the present embodiment is not intended to limit the scope of the present invention but is presented by way of example only.

Example 1

As shown in FIG. 1, a poly (4,4'-hexafluoroisopropylidene / 2,5-difluorobenzene) ether formed by a coupling reaction on a substrate 10 on which the metallization layer 20 is formed is a cyclonucleotide solvent. After spin-coating the solution formed in a 25% by weight ratio to a thickness of about 1,000 ~ 10,000Å as shown in Figure 2, it is baked to remove the solvent at 150 ℃ to 250 ℃. The low dielectric material coated on the wafer thus has hydroxy end groups in chemical structure.

The low dielectric material layer 30 coated thereon is placed in a vacuum chamber to react the vaporized silylation agent with the low dielectric material layer 30 at 90 to 170 ° C. for 30 to 300 seconds (FIG. 3). To form a low dielectric layer 35 of poly (4,4'-hexafluoroisopropylidene / 2,5-difluorobenzene) ether having a terminal of a trimethyl silane as shown in Table 1 below. 4).

The description with reference to the drawings is omitted from Example 2 in which Example 1 and the low dielectric constant material are different.

Example 2)

A wafer is prepared by forming a poly (4,4'-hexafluor isopropylidene / 2,3,5,6-tetrafluorobenzene) ether formed by a coupling reaction in a cyclopentanone solvent at a ratio of 20% by weight. Spin-coated to and then baked at 150 ° C. to 250 ° C. for solvent removal. This was silicided in the gas phase at 90 ° C. to 170 ° C. for 30 seconds to 300 seconds as in Example 1 to obtain a poly (4,4′-hexafluoro iso having an end group of trimethylsilane as shown in Table 3 below. A low dielectric material layer of propylidene / 2, 3,5,6-tetrafluorobenzene) ether is formed.

Example 3

150 ° C. to 250 ° C. after spin coating a solution in which a poly (4,4′-hexafluoro isopropylidene / benzene) ether formed by a coupling reaction was formed at a ratio of 20% by weight in an n-methylpyrrolidine solvent to a wafer. Bake for solvent removal at < RTI ID = 0.0 > This was silylated in the gas phase at 90 ° C. to 170 ° C. for 30 seconds to 300 seconds as in Example 1 to obtain a poly (4,4′-hexafluoro isopropyl having end groups of trimethyl silane as shown in Table 1 below. A low dielectric material layer of leaden / benzene) ether is formed.

Example 4

A poly (4,4'-hexafluoroisopropylidene / 2-fluorobenzene) ether formed by the coupling reaction in a solvent of dimethyl acetamide in a ratio of 15% by weight to spin-coated wafers and then 150 to Bake for solvent removal at 250 ° C. This was silylated in the gas phase for 30 seconds to 300 seconds at 90 ° C. to 170 ° C. as in Example 1 to obtain a poly (4,4′-hexafluoro iso having an end group of trimethyl silane as shown in Table 5 below. A low dielectric material layer of propylidene / 2-fluorobenzene) ether is formed.

Example 5

After spin-coating a solution of poly (4,4'-isopropylidene diphenol / 2,5-difluorobenzene) ether formed by a coupling reaction in a solvent of dimethyl formamide at a ratio of 30% by weight on a wafer Bake for solvent removal at 150 ° C. to 250 ° C. This was silylated in the gas phase at 90 ° C. to 170 ° C. for 30 seconds to 300 seconds as in Example 1 to obtain a poly (4,4′-isopropylidene having end groups of trimethyl silane as shown in Formula 6 below. A low dielectric material layer of diphenol / 2,5-difluorobenzene) ether is formed.

Example 6

A solution of poly (4,4'-isopropylidene diphenol / 2,3,5,6, tetrafluorobenzene) ether formed by a coupling reaction in a cyclohexanone solvent in a ratio of 25% by weight was placed on a wafer. After spin coating, the solution is baked at 150 ° C to 350 ° C for solvent removal. This was silylated in the gas phase for 30 seconds to 300 seconds at 90 ° C. to 170 ° C. as in Example 1 to obtain a poly (4,4′-isopropylidene having end groups of trimethyl silane as shown in Table 7 below. A low dielectric material layer of diphenol / 2,3,5,6, -tetrafluorobenzene) ether is formed.

Example 7

Poly (4,4'-isopropylidene diphenol / benzene) ether formed by the coupling reaction in a n-methyl pyrrolidine solvent at 25% by weight of a solution formed by spin coating on a wafer, then 150 ℃ to 250 Bake for solvent removal at < RTI ID = 0.0 > This was silylated in the gas phase for 30 seconds to 300 seconds at 90 ° C. to 170 ° C. as in Example 1, to obtain a poly (4,4′-isopropyl) having terminal groups of trimethyl silane as shown in Table 8 below. A low dielectric material layer of dendiphenol / benzene) ether is formed.

Example 8

150 [deg.] C. after spin coating a solution in which a poly (4,4'-isopropylidene diphenol / 2-fluorobenzene) ether was formed at a ratio of 20% by weight in an n-methyl pyrrolidine solvent by a coupling reaction on a wafer Bake for solvent removal at -250 ° C. This was silylated in the gas phase for 30 seconds to 300 seconds at 90 ° C. to 170 ° C. as in Example 1 to obtain a poly (4,4′-isopropylidene having end groups of trimethyl silane as shown in Formula 9 below. A low dielectric material layer of diphenol / 2-fluorobenzene) ether is formed.

Example 9

A solution of poly (4-biphenyl / 2,5-difluorobenzene) ether formed by the coupling reaction in a cyclopentanone solvent at a ratio of 15% by weight was spin coated on a wafer, and then the solvent was heated at 150 ° C to 250 ° C. Bake for removal. This was silylated in the gas phase for 30 seconds to 300 seconds at 90 ° C. to 170 ° C. as in Example 1 to obtain a poly (4-biphenyl / 2,5 having terminal groups of trimethylsilane as shown in Formula 10 below. Form a low dielectric material layer of difluorobenzene) ether.

Example 10)

After spin-coating a solution in which a poly (4-biphenyl / 2,3,5,6-tetrafluorobenzene) ether formed by a coupling reaction was formed in a dimethyl acetamide solvent at a ratio of 30% by weight on a wafer, it was 150 to Bake at 250 ° C. for solvent removal. This was silylated in the gas phase for 30 seconds to 300 seconds at 90 ° C. to 170 ° C. as in Example 1 to obtain a poly (4-biphenyl / 2,3 having end groups of trimethyl silane as shown in Formula 11 below. A low dielectric material layer of 5,6-tetrafluorobenzene) ether is formed.

Example 11

A solution of poly (4-biphenyl / benzene) ether formed by the coupling reaction at a ratio of 15% by weight in a solvent of dimethyl formamide is spin coated on a wafer and then baked at 150 ° C to 250 ° C for solvent removal. . Poly (4-biphenyl / benzene) ether having the end group of trimethylsilane as shown in Formula 12, by silicidation in the gas phase for 30 seconds to 300 seconds at 90 ℃ to 170 ℃ as in Example 1 To form a low dielectric material layer.

Example 12)

A solution in which a poly (4-biphenyl / 2-fluorobenzene) ether formed by a coupling reaction was formed at a ratio of 20% by weight in a cyclohexanone solvent was spin coated on a wafer, and then the solvent was removed at 150 ° C to 250 ° C. Bake. This was silylated in the gas phase for 30 seconds to 300 seconds at 90 ° C. to 170 ° C. as in Example 1 to obtain a poly (4-biphenyl / 2-fluorine having end groups of trimethylsilane as shown in Formula 13 below. Benzene) ether.

Example Number Polyarylene ether compound of trimethylsilane terminal group of the present invention Chemical formula number Example 1 Formula 2 Example 2 Formula 3 Example 3 Formula 4 Example 4 Formula 5 Example 5 Formula 6 Example 6 Formula 7 Example 7 Formula 8 Example 8 Formula 9 Example 9 Formula 10 Example 10 Formula 11 Example 11 Formula 12 Example 12 Formula 13

Example 13

The dielectric constant, water absorption rate, glass transition temperature, and pyrolysis start temperature of the low dielectric films of Chemical Formulas 2 to 13 using the gas phase silylation process according to the present invention obtained in Examples 1 to 12 were measured according to the following method. At this time, each compound was compared with the compound having no trimethylsilane end group as a control group.

end. Dielectric constant measurement

After depositing a silicon Weifeng oxide film and aluminum, the low dielectric was coated thereon according to Examples 1 to 12 according to the present invention. A specimen was fabricated by sputtering platinum (Pt) onto the upper electrode using a shadow mask. The size of the dot pattern produced by this method was produced with a diameter of 0.6㎛. The measurement was performed by measuring the frequency at 1 MHz when measured using the C-V method in the HP4284 LCR meter, and the results are shown in Table 2 below.

I. Water absorption

The low-dielectric sample formed according to Examples 1 to 12 according to the present invention was gradually heated using a TDS (Thermal Desorption Spectroscopy) equipment while detecting its characteristic peak and intensity at the molecular weight (18) position of water. The water absorption rate of was measured. The results are shown in Table 2 below.

All. Glass transition temperature measurement

The glass transition temperature for the low dielectric formed in accordance with Examples 1 to 12 according to the present invention was measured using a differential scanning calorimeter (DSC). That is, the glass transition temperature at the time of heating to a temperature before the pyrolysis temperature and then rapidly cooled to a low temperature below room temperature to make the sample amorphous, and then reheated was measured. At this time, the heating rate was 10 ° C / min. The results are shown in Table 2 below.

la. Pyrolysis Start Temperature Measurement

The pyrolysis start temperature for the low dielectric formed in accordance with Examples 1 to 12 according to the present invention was measured using TGA (Thermal Gravimetric Analysis) method. The heating rate was 20 ° C./min, and the temperature at which 1% by weight loss occurred was measured as the start temperature of pyrolysis.

matter Dielectric Constant (0% Moisture / 1 MH _Z ) Water Absorption Rate (Wafer Level%) Glass transition temperature (℃) Pyrolysis start temperature (℃) Silane group-containing substance Silane-Free Material Silane group-containing substance Silane-Free Material Nitrogen stream Air flow Formula 2 2.57 2.93 0.62 0.70 330 460 443 Formula 3 2.45 2.81 0.31 0.35 341 472 449 Formula 4 2.78 3.14 0.93 1.07 317 475 453 Formula 5 2.63 2.92 0.52 0.68 325 463 441 Formula 6 2.74 3.07 0.74 0.92 320 453 435 Formula 7 2.67 3.02 0.52 0.63 325 462 442 Formula 8 2.96 3.25 1.14 1.27 297 468 445 Formula 9 2.88 3.18 0.73 0.85 308 452 428 Formula 10 2.68 3.02 0.42 0.49 345 487 463 Formula 11 2.57 2.89 0.21 0.27 356 495 472 Formula 12 2.84 2.85 0.53 0.62 332 482 458 Formula 13 2.75 3.04 0.32 0.38 340 483 465

In Table 2, the silane group-containing material refers to a low dielectric material corresponding to Chemical Formulas 2 to 13 of Examples 1 to 12 according to the present invention, and the silane group-free material is the same structure as the low dielectric material of Chemical Formulas 2 to 13, respectively. As a substance having no silane group.

The low dielectric thin film using the gas phase silylation process formed according to the method according to the present invention from the experimental results of Table 2 is suitable for insulation of the semiconductor metal wiring layer with a dielectric constant of 3.0 or less, and has no conventional arylene group-based polyarylene ether-based low The dielectric constant is reduced to about 12.8% maximum than the dielectric film, it can be confirmed that the excellent insulation.

In addition, it can be seen that the water absorption rate is reduced by up to about 23.5% than the conventional polyarylene ether-based low dielectric film containing no silane group, and the thermal decomposition start temperature is also 450 ° C or higher, which is very stable at high temperature. have.

As described above, according to the low dielectric film forming method using the gas phase silylation process according to the present invention, a gaseous agent containing a silicon having a hydrophobic group on the hydroxy end group of a conventional polyarylene ether-based low dielectric constant material is vapor-free without an acid catalyst. In addition, since the chamber in which the process is performed is carried out in a vacuum state, no silylation agent remains so that the residual silylation agent does not affect subsequent processes. In particular, since the silylation is carried out in one chamber, it is possible to exclude the contact of moisture during the process, and the introduction of the silicon group may increase the dielectric constant, water absorption and thermal stability of the polyarylene ether system.

Claims (7)

Forming a low dielectric constant material layer having hydroxy end groups; And a vapor phase sillation step of silicifying the low dielectric constant material layer by introducing a vapor of a silylation agent into a chamber. The method of claim 1, wherein the thickness of the low dielectric constant material layer is 1000 to 10000 GPa. The method of claim 1, wherein after forming the low dielectric constant material layer, baking is performed for 20 to 300 seconds at a temperature ranging from 150 ° C. to 250 ° C. to remove the solvent. The method of claim 1, wherein the vapor phase sillation is performed at a temperature in a range of 30 to 300 seconds in a range of 50 to 250 ° C. The method of claim 1, wherein the hexamethyl disilazane, tetramethyl disilazane, bisdimethylamino dimethylsilane, bisdiethylamino methylsilane, dimethylsilyl dimethylamine, dimethylsilyl diethyl A method for forming a low dielectric film of a semiconductor device, characterized by using one selected from the group consisting of amine, trimethylsilyl dimethylamine, trimethylsilyl diethylamine, or dimethylamino pentamethyldisilane. Forming a polyarylene ether-based low dielectric constant material layer having a basic structure of Formula 1 having a hydroxy end group or a benzene group substituted with one or more fluoro groups; The vapor of the silylation agent is introduced into the chamber to be silylated in the gas phase using the polyarylene ether system having a basic structure of Formula 2 or a benzene group substituted with one or more fluoro groups and having a terminal group of trimethylsilane. A method of forming a low dielectric film of a semiconductor device, comprising the step of forming a thin film of a compound. N is an integer equal to 0 or 1, X is , or ego, Y is a halogen element. The low dielectric constant thin film is formed by forming a low dielectric constant material layer having a hydroxyl end group on a silicon substrate, and then vaporizing the low dielectric constant material layer by introducing a vapor of a silicide agent into a chamber.