Low-Impurity Organosilicon Product As Precursor For CVD

a technology of organosilicon and low impurity, which is applied in the field of low dielectric constant materials prepared, can solve the problems of low density through space-filling with bulky chsub>x /sub>bonds, unpractical treatment of dichloromethylsilane, and particularly vulnerable to attack and undesirable effects

Inactive Publication Date: 2007-12-13
VERSUM MATERIALS US LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an organosilicon composition that is free of chloride salt formation when mixed with other organosilicon materials. This is achieved by limiting the concentration of chloride and chloride scavenger in the organosilicon composition to prevent the formation of solids when used in chemical vapor deposition processes. The invention also provides a method for purifying the organosilicon composition by contacting it with a stoichiometric excess of a basic chloride scavenger to precipitate dissolved residual chloride as a chloride salt, removing it, and then contacting it with an acid gas to form a salt of the acid gas upon reaction with the excess basic chloride scavenger. The purified organosilicon composition is suitable for use in various applications such as chemical vapor deposition processes.

Problems solved by technology

The incorporation of such organic groups also serves to “open up” the structure of the silica, possibly leading to lower density through space-filling with bulky CHx bonds.
This is particularly true for the synthesis of DEMS, in which it is not practical to treat the dichloromethylsilane starting material with a substantial molar excess of reactant in order to drive the reaction to quantitative conversion.
The presence of Si—H in the dichloromethylsilane makes it particularly vulnerable to attack forming undesirable side-reaction products if exposed to a substantial excess of either ethanol (CH3CH2OH) or triethylorthoformate ((CH3CH2O)3CH).
Given these constraints, the crude DEMS product typically has a significant amount of acid chlorides (HCl) and / or complexed silicon chloride impurities.
Distillation is effective for removing most of the chloride impurities, but has limited efficacy for reducing the chlorides to the low levels required for CVD precursor source chemicals (e.g., <10 ppm by weight).
Residual chloride presents integration issues due to its potential migration and high reactivity.
Nitrogen also needs to be minimized because of its potential for diffusion, possibly causing resist poisoning issues.
Consequently, unacceptably high levels of halogen or nitrogen in CVD feed materials may cause undesirable performance problems for the resulting ILD films.
As described above, two common routes for the preparation of DEMS are exemplified, each of which may yield unacceptably high levels of chloride contamination in the crude product due to unreacted starting material, acid chloride or complexed chloride byproducts.
Distillation is commonly employed to purify the crude product, but it is not an effective means for reducing the chloride to acceptable levels.
There are significant drawbacks, however, associated with the use of residual chloride scavengers.
Solids formation in this manner leads to production problems because the solid precipitate typically restricts or blocks the flow of the liquid precursor, contaminates the liquid delivery or deposition hardware, and numerous potential performance and or quality issues associated with the deposited low-k films.

Method used

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Examples

Experimental program
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example 1

Preparation of Standards for Determination of Phase Diagram for EDA and HCl in DEMS.

[0065] Five samples of DEMS were prepared for use as standards or as components to prepare standard for the experiments described herein. (1) 1-1: 100 g of DEMS with 798 ppm EDA and 2.0 ppm chloride; (2) 1-2: 500 g of DEMS with no EDA and 2.0 ppm chloride; (3) 1-3: 150 g of DEMS with no EDA and 24 ppm chloride; (4) 1-4: 300 g of DEMS with no EDA and 1.4 ppm Cl—; and (5) 1-5: 200 g of DEMS with 310 ppm of EDA and 2.1 ppm of chloride.

[0066] The 53.2 ppm EDA in DEMS standard was made by combining 30.08 g of 1-1 with 421.01 g of 1-2. A DEMS sample with 202 ppm of EDA was then prepared by combining 320 g of the 53.2 ppm EDA sample with 80.28 g of 1-1 to form about 400 g of a sample with 202 ppm of EDA. The 17.0 ppm chloride in DEMS was prepared by combining 31.21 g of 1-4 with 69.45 g of 1-3. The 12.0 ppm chloride in DEMS was prepared by combining 53.19 g of 1-4 with 47.35 g of 1-3. The 9.0 ppm chloride...

example 2

Precipitation Experiments.

[0067] The standards described in Example #1 were used to carryout several precipitation experiments to define the phase diagram for EDA and HCl in DEMS. For each of these experiments, the EDA-containing DEMS was added drop-wise to the chloride-containing DEMS until the first sign of permanent visible turbidity was evident. The experiment was performed using a well lit dry box to improve visibility. A turbidity meter was used to verify the turbidity of the solution once the end-point was reached. A summary of the results is shown in Table 1. The phase diagram generated by these experiments is shown in FIG. 2.

[0068] Chloride level #1. The intent of this experiment was to determine the minimum amount of EDA that needed to be added to a DEMS solution containing 9.0 ppm chloride in order to cause the hydrochloride salt to precipitate. For this test 100.61 g of DEMS containing 9.0 ppm of chloride was placed in a 500 ml round-bottomed flask. A second sample of ...

example 3

[0076] A 16 L sample of diethoxymethylsilane (DEMS) was analyzed by gas chromatography to contain 368 ppm of ethylenediamine (EDA). EDA had been used as a scavenger to remove the residual chloride following the synthesis of the DEMS. The residual EDA in the sample was present because a stoichiometric excess had been used to ensure optimal removal of the chloride species. The 16 L sample was transferred into a 20 L flask under inert gas conditions. The DEMS liquid was flooded with CO2 gas for 90 minutes at a rate of about 2 to 3 liters per minute. An immediate precipitation of a milky white solid was observed upon the initial contact of CO2 with the DEMS liquid. The 20 L flask was purged with N2 gas to establish an inert atmosphere in the headspace above the liquid. The following day the solid was separated from the DEMS liquid by filtering the product through a 0.2 micron filter under inert gas conditions. The filtered liquid was evacuated, then back-filled with ambient pressure N2....

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Abstract

The present invention provides an organosilicon composition comprising diethoxymethylsilane, a concentration of dissolved residual chloride, and a concentration of dissolved residual chloride scavenger that does not yield unwanted chloride salt precipitate when combined with another composition comprising diethoxymethylsilane.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of priority under 35 U.S.C. § 119(e) to earlier filed U.S. patent application Ser. No. 60 / 813,087, filed on Jun. 13, 2006, the disclosure of which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION [0002] The present invention is related to the field of low dielectric constant materials prepared by chemical vapor deposition (CVD) methods which serve as insulating layers in electronic devices. In particular, the present invention is directed to compositions for use as precursors to the low dielectric constant materials that have predetermined concentration limitations of certain impurities to eliminate process problems related to precipitation of such impurities. [0003] The electronics industry utilizes dielectric materials as insulating layers between circuits and components of integrated circuits (IC) and associated electronic devices. Line dimensions must be reduced in o...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): C07F7/08
CPCC07F7/20C07F7/1868C07F7/1804C08L83/06C08K3/16C08L83/00
InventorMAYORGA, STEVEN GERARDO'NEILL, MARK LEONARDCHANDLER, KELLY A.
OwnerVERSUM MATERIALS US LLC