DD233748A3 - VAPOR MATERIAL FOR OBTAINING EXTREMELY HIGH IMPORTS - Google Patents

Abstract

The invention relates to a vapor deposition material comprising a mixture of Si and SiO 2 to achieve extremely high vapor deposition rates in the production of SiO 2 layers in a vacuum. SiO 2 layers are used, for example, as interference or protective layers in the surface treatment of glasses or of electronic components. According to the invention, the object is achieved in that the SiO 2 contains strongly hydrogen-bonded silanol groups which absorb in the wavenumber range of 930 to 970 cm -1.

Description

Field of application of the invention

The invention relates to a vapor deposition material for achieving extremely high vapor deposition rates in the production of silicon monoxide layers by vacuum evaporation. The vapor deposition material is used in particular for the production of interference or protective layers for a surface treatment of substrates, such. As glass panels for use as mirrors, construction glasses u.a., And used by electronic components.

Characteristic of the known technical solutions

Silicon monoxide layers are produced by evaporation of lumpy silicon monoxide or mixtures of silicon and silicon dioxide with the addition of inorganic or organic binders in vacuo. The particulate silicon monoxide has the disadvantage that it is produced in a separate, energy and labor consuming vacuum process. The mixtures of silicon and silicon dioxide, which are provided with inorganic binders according to DD-PS 152120 or with organic binders according to DD-PS 159003, have i.a. the disadvantage that with them no high evaporation rates can be achieved and fluctuations in the vapor deposition rates are recorded. '

Object of the invention

It is to be created a vapor deposition of a mixture of silicon and silicon dioxide, which ensures extremely high vapor deposition rates in the production of Siliziummonoxidschichten.

Explanation of the essence of the invention

The invention has for its object to provide a vapor deposition of a mixture of silicon (Si) and silicon dioxide (SiO ₂ ), are achieved with the extremely high vapor deposition rates in the production of layers of silicon monoxide (SiO) in a vacuum.

It has surprisingly been found that the object is achieved if SiO ₂ produced by hydrolysis of SiCl ₄ or by flame hydrolysis in the gas phase of SiCl ₄ is used, which contains in its structure strongly hydrogen-bonded silanol groups which in the IR spectrum as = SiO-H stretching vibration can be indicated by absorption at wavenumbers of 930 ... 970cm ~ ¹

 The well-known equation of formation

SiO ₂ + Si- »2 SiO t (D

gives the actual SiO formation processes to simplified and insufficient again. Achieving the extremely high vapor deposition rates in the production of SiO ₂ layers using SiO ₂ with strongly hydrogen-bonded silanol groups becomes understandable only by considering the following intermediate intermediary structures:

I ο *

ps5i-0 ··· OH-Si ^ ^ 5i-0-5i ^ fH₂0 (2)

Vacuum * ·

1 Z00 - ILOO ⁰ C * MOO-ILOO ⁰ C _. _nc . , _a .

, Ξ? oil - 0 - 5t s5 55t- · OSt ^ (3)

Vacuum vacuum

Due to the presence of the strong hydrogen bonding interaction of the silanol groups according to equation (2), the activation energy of the proton diffusion is greatly reduced and the dehydroxylation of the SiO ₂ surface is promoted in cooperation with the removal of the water formed during the reaction in vacuo. The formation of new siloxane bonds (marked with *) leads to stresses in the SiO ₂ lattice. These rearrangement processes at the surface take on further Tempaiutursteigerung under vacuum the entire volume phase and lead to the splitting of extremely "strained" and thus energetically excellent Siloxanbindungen to form the formulated in equation (3) radical and ionic centers, apparently for the high reactivity of SiO ₂ , which contains strongly hydrogen-bonded silanol groups, are responsible in the reaction with Si according to the following equation.

<Si = θ! + -St -O-Si · ...

-Si-Q -Si .. O · + · «Si

When metallic Si acts as a reactant, the reaction will begin at the radical centers to form gaseous monomeric SiO (| Si = O). Reduction of the SiO ₄ tetrahedron to a lower oxygen structure increases the likelihood of creating new strained siloxane bonds in this tetrahedron and maintains the high reactivity of the SiO ₂ with strongly hydrogen bonded silanol groups.

To interpret the extremely high vapor deposition rates, the SiO _{2 was} investigated by strong hydrogen-bonded silanol groups after compression in KBr IR spectroscopy, in Fig. 1, the IR spectra in the initial state (curve 1) and after two hours of thermal stress at 1400 ⁰ C (curve 2 ). The following results can be read:

- The absorption at a wave number of 930cm " ¹ is greatly reduced in curve 2 over curve 1 in their intensity.

- The absorptions at the wavenumbers of 800 cm " ¹ and 480 cm" ¹ are greatly increased in curve 2 over curve 1 in their intensity.

- The wave numbers 88OcITr ¹ ^ OCm ^"1 and 620cm ~ ¹ new absorptions occur at Turn 2 with respect to curve the first

The position of the absorption maximum of the asymmetric Si-O-Si stretching vibration is shifted from the wavenumber 1100 cm ^-1 (curve 1) to the wavenumber 1080 cm ^-1 (curve 2).

The multitude of changes suggests intensive structural transformations during thermal stress, which account for the extremely high vapor deposition rates. So z. For example, in the literature, absorption at a wavenumber of 880 cm ^{-1 is} attributed to the presence of reduced SiO 4 tetrahedra of the Si (SiO 2) type, absorption at a wavenumber of 620 cm ^-1 indicates structural defects, species of different tetrahedral symmetry co-exist. see also equation (4).

For the interpretation of the low vapor deposition rates, the IR spectroscopic investigation of SiO ₂ , which does not contain hydrogen-bonded silanol groups. Fig. 2 shows the relevant IR spectra in the initial state (curve 1) and after two hours of thermal stress at 1400 ⁰ C (curve 2), the following results can be read:

- An absorption at a wave number of 930cm " ¹ does not exist.

- The absorptions at the wavenumbers of 800cm " ¹ and 470-450cm" ¹ are hardly changed in their intensity.

- A new absorption occurs only weakly at a wave number of 620cm " ¹ .

The position of the absorption maximum of the asymmetric Si-O-Si valence oscillation is shifted from the wavenumber 070 cm ^-1 (curve 1) to 1080 cm ^-1 (curve 2).

Upon thermal loading of this SIO ₂ , significantly less or no pronounced structural changes occur compared with SiO ₂ , which contains strongly hydrogen-bonded silanol groups.

embodiment

160 g of SiO ₂ with hydrogen-bonded silanol groups are mixed with 70 g of Si, pressed and introduced into a cylindrical vaporizer crucible made of molybdenum with the dimensions d = 105 mm and h = 35 mm. For comparison, a mixture of 160 g of SiO ₂ without hydrogen-bonded silanol groups and 70 g of Si is introduced into a second evaporator crucible of the same size and the same material.

At a pressure of 5.33 × 10 ^-3 Pa, both evaporator crucibles are heated individually and successively, and the vapor deposition rate is determined indirectly with the aid of a suitable transmission measuring device as a function of the evaporator output with SiO ₂ with hydrogen-bonded silanol groups and curve 2 the mixture with SiO ₂ without hydrogen-bridged silanol groups.

Even with considerable evaporator performance, the vapor deposition rate of 20 nm / s is not exceeded according to curve 2, while it constantly increases according to curve 1. At an evaporator power of 3.3 kW, the vapor deposition rate is e.g. by a factor of 10 higher.

Claims (3)

Invention claim: 1. vapor deposition material to achieve extremely high vapor deposition rates for the production of silicon monoxide layers in vacuo from a mixture of silicon and sol silicon dioxide, characterized in that the silica contains strongly hydrogen bonded silanol groups. 2. Aufdampfmaterial after item!, Characterized in that the strongly hydrogen-bonded silanol groups in the wavenumber range of 930 ... 970Cm " ¹ absorb. For this 3 pages drawings