WO1998015504A1 - Reactive ion etching of silica structures - Google Patents
Reactive ion etching of silica structures Download PDFInfo
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- WO1998015504A1 WO1998015504A1 PCT/AU1997/000663 AU9700663W WO9815504A1 WO 1998015504 A1 WO1998015504 A1 WO 1998015504A1 AU 9700663 W AU9700663 W AU 9700663W WO 9815504 A1 WO9815504 A1 WO 9815504A1
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- etching
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- sidewall
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32082—Radio frequency generated discharge
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C15/00—Surface treatment of glass, not in the form of fibres or filaments, by etching
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/13—Integrated optical circuits characterised by the manufacturing method
- G02B6/136—Integrated optical circuits characterised by the manufacturing method by etching
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12166—Manufacturing methods
- G02B2006/12173—Masking
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12166—Manufacturing methods
- G02B2006/12176—Etching
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/32—Processing objects by plasma generation
- H01J2237/33—Processing objects by plasma generation characterised by the type of processing
- H01J2237/334—Etching
Definitions
- the present invention relates to creation of silica structures and in particular to the reactive ion etching of such structures.
- Silica-based channel waveguides fabricated on silicon or silica wafer substrates, are potential building blocks of planar lightwave circuits (PLCs) that are becoming increasingly important for telecommunications systems.
- PLCs planar lightwave circuits
- RIE reactive ion etching
- RIE of silica glass in integrated circuit (IC) manufacture is a well established and routine process with, for example, CHFj based mixtures being used to obtain high selectivity over photoresist.
- the silica films used in planar waveguides have several unique differences which influence the development of suitable RIE processes. Firstly, the thicknesses of silica in waveguide devices can be as much as 5 to 10 urn, as opposed to typically less than 1 ⁇ m in IC technology. This places extra demands on mask thickness and/or material selectivities, as well as on the silica etch rate which should be high enough to obtain reasonable throughput.
- etching materials such as photoresist, amorphous silicon (a-Si) and chromium have been reported.
- photoresist amorphous silicon
- chromium chromium
- the use of non-photoresist masks allows for larger etching depths and silica etch rates.
- the roughness of the etched walls of the waveguide structures or light turning mirrors should ideally be as small as possible in order to reduce the loss due to light scattering.
- a number of works on sidewall roughness reduction for etching with photoresist masks have been reported. In these cases, however, the etching depth of a Si0 2 layer was restricted to around 1 ⁇ m.
- Etched profile control is also important and some slope in the etched profile is sometimes desirable in order to facilitate filling of the gaps between closely spaced waveguides during cladding deposition.
- Profile slope is normally achieved by controlled photoresist mask erosion.
- a method for etching of silica- based glass layers or substrates comprising reactive ion etching through a mask executed under conditions of simultaneous isotropic deposition of a carbon based polymer.
- the polymer deposition rate or/and its steady-state thickness on different surfaces of the etched structure is controlled by adjusting one or several process control parameters in order to control etched profile, dimension loss, sidewall and bottom etched surface roughness, and etching selectivity between the silica-based layer and mask material.
- a gas or a mixture of gases containing fluorine or carbon atoms is used and a photoresist mask or other form of mask such as amorphous silicon.
- Adjustable parameters can include RF power and substrate temperature. The temperature can be adjusted to achieve low sidewall roughness and low dimension loss at the same time. Further, resputtering of any metal present wihtin or/and m contact with the discharge zone can be prevented.
- the invention is ideally suited wherein reactive ion etching is performed m a high plasma density hollow cathode etching system and the etching gas mixture is CH 3 F and Argon .
- a high plasma density hollow cathode etching system which has been shown to provide higher etch rates than those achievable m previously known standard RIE systems.
- Etching was carried out m a CHF 3 /Ar mixture with additions of 0 2 and CF 4 .
- the effects of the different chemistries as well as the use of different masks (photoresist and amorphous silicon) and the effects the substrate temperature on etching rates, sidewall roughness and etch profiles have been investigated. Using a photoresist mask generally results m greater sidewall roughness compared to an amorphous silicon mask.
- polymer deposition during the etching process can exacerbate the development of roughness but is still desirable to a certain extent m the prevention of the loss of line width during etching.
- Two mechanisms of polymer deposition control are disclosed, namely, the addition of varying amounts of 0 2 or CF 4 , and elevating the temperature of the substrate. The latter was found to give a good compromise between control over the line width loss and the sidewall roughness.
- a simple phenomenological model based on a polymer etching/deposition rate equilibrium on etched surfaces is proposed and examined. Brief Description of the Drawings
- Fig. 1 is a schematic illustration of the basic layout of hollow cathode discharge chamber used in the preferred embodiment .
- Fig. 2a to Fig. 2g illustrate graphs of etch rates and selectivities over mask material for etching with a-Si (Fig. 2a) and photoresist (Fig. 2g) masks as a function of RF power.
- Pressure is 12 Pa.
- Sample temperature is 80°C.
- Fig. 3a to Fig. 3d illustrate graphs of etching profile slope (Fig. 3a) dimension loss (Fig. 3b), sidewall roughness (Fig. 3c) and polymer deposition rate (Fig. 3d) as a function of RF power for etching with a-Si and photoresist masks.
- the pressure is 12 Pa.
- the sample temperature is 80°C.
- the dimension loss was normalized to an etching depth of 5 urn.
- the polymer deposition rate was measured in the area shielded from ion bombardment.
- Fig. 4a to Fig. 4h are Electron microscope images of etching profiles as a function of RF power for etching with a-Si (Fig. 4a to Fig. 4d) and photoresist masks (Fig. 4e to Fig. 4h) .
- the RF power was as follows: Fig. 4a- unetched a-Si mask, Fig. 4b- 250W, Fig. 4c-500W, Fig. 4d-650W, Fig. 4e-unetched photoresist mask, Fig. 4f-300W, Fig. 4g-400W, Fig. 4h 500W.
- Pressure is 12 Pa.
- Gas flow rates 60 seem of Ar, 15 seem of CHF 3 . Sample temperature 80 °C.
- Fig. 5a to Fig. 5e illustrate graphs of etch rates and selectivities with Fig. 5a to 5c illustrating Si0 2 etch rates and selectivities over an a-Si mask and Fig. 5d to Fig. 5e illustrating vertical and lateral etch rates of a-Si mask as a function of sample temperature, for a 0 2 flow rate and a CF 4 flow rate, respectively.
- RF power is 500W. Pressure is 12 Pa. Gas flow rates: 60 seem of Ar, 15 seem of CHF 3 . Sample temperature 80°C unless varied.
- Fig. 6a to Fig. 6j illustrate graphs of the etching profile slope (Fig. 6a to Fig. 6c) sidewall roughness (Fig. 6d to Fig. 6f) and polymer deposition rate (Fig. 6g to Fig. 6j ) as a function of sample temperature, 0 2 flow rate and CF 4 flow rate, respectively using an a-Si mask.
- RF power is 500W
- the surfaces include (i) the top surface of the mask 31, (ii) the sidewalls of the mask 32, (iii) the sidewalls of Si0 2 33 and, (iv) the bottom surface of the Si0 34.
- a steady state thickness of polymer film can be present on (i-iii) , whereas (iv) is assumed polymer free under the etching conditions used in this study.
- Fig. 9a to Fig. 9c are electron microscope images of time evolution of the etched profile: with Fig. 9a showing an unetched a-Si mask, Fig. 9b after 3 minutes etching, Fig. 9c after 6 minutes etching.
- RF power is 500W.
- Pressure is 12 Pa.
- Sample temperature is 80 °C.
- Etching selectivity over the a- Si mask is approximately 14:1.
- a "negative undercut" is shown to be developed without mask width reduction. The more vertical profile of the a-Si mask is "buried" under polymer formed at a steady state angle determined by the polymer etching and deposition equilibrium.
- Fig. 10 is a schematic illustration of a mechanism of sloped profile formation.
- Fig. 11a and lib illustrate etched sidewalls for etching with a photoresist mask (Fig. 11a) and a a-Si mask (Fig. llg) .
- Pressure is 12 Pa.
- Sample temperature is 80°C.
- RF power is 500W for etching with the photoresist mask and 650W for etching with the a-Si mask. Description of Preferred Embodiments
- a first embodiment of the present invention relies upon the utilisation of plasma enhanced chemical vapour deposition (PECVD) in a hollow cathode discharge chamber.
- PECVD plasma enhanced chemical vapour deposition
- a suitable vacuum chamber assembly 10 including a top electrode 11 and a bottom electrode 12 connected as shown to RF source 13 which comprised a 13.56 MHz RF source.
- the chamber 14 is evacuated via pump port 15 and gases such as CH 4 /SF 6 mixtures, CHF 3 /Ar mixtures are introduced via corresponding ports e.g. 16, 17, so as to cause controlled etching on wafers or substrates 19 located in the RF field induced plasma located between electrodes 11, 12.
- This apparatus 10 is utilised to perform the controlled ion etching operation as discussed in detail below.
- the high plasma-density hollow cathode discharge etching system suitable for use is described in C.M. Horwitz, S. Boronkay, M. Gross and K.E. Davies, J. Vac. Sci . Technology A6, at pages 1837 to 1844 (1988) .
- the two opposing RF powered parallel circular electrodes 11, 12 are surrounded by a grounded chamber 21.
- a conventional diode discharge is produced between each of the electrodes 11, 12 and the grounded chamber 21 but a high density plasma is generated between the two RF powered electrodes 11, 12 due to the "electron mirror" effect.
- Both the upper and lower electrodes were water-cooled and covered with 100 mm diameter silicon wafers 18, 19.
- the latter is to prevent resputtering of the electrode material (Al) which can result in metal contamination and subsequent surface roughness and tne formation of sloped etching profiles due to metal-based polymer deposition.
- Examination of the polymer deposited m the lon-snielded areas (as described below) using wavelength dispersive X-ray spectroscopy ( DS) showed that no traces of Al or other vacuum chamber materials could be detected at the 0.01 - level, thus confirming that metal contamination is not an issue.
- the silica films used in the etching experiments had a thickness of 8 urn and were deposited on silicon substrates 19 using the hollow-cathode PECVD technique.
- Masking layers of 1 ⁇ m of PECVD a-Si or 2 urn of photoresist were then applied to the wafer 19.
- the photoresist mask was patterned using conventional photolithography, while patterning of the a-Si layer was carried out using conventional photolithography followed by etching m a CF 4 /SF 6 mixture.
- the samples 19 were etched to a depth of around 4-5 ⁇ m, with the rates determined by surface profllo etry .
- the etched profile, sidewall roughness and dimension loss were further determined by SEM examination.
- the dimension loss was calculated or defined as the difference between the line width measured at the bottom of the mask oefore etching and the width at the top of the etched ridge.
- Sidewall roughness figures set out hereinafter are the average amplitudes of the RIE- mduced corrugations measured over a distance of a few microns.
- the initial (unetched) roughness of both the photoresist and a-Si mask edge was not larger than 0.02 ⁇ m.
- the silica films were etched m a 20 t CHF 3 in Ar mixture w th various additions of CF 4 or 0 ⁇ .
- the pressure was kept at 12 Pa m all experiments. All gases had a stated purity of 99.95 % or better. Etching m CHF 3 was accompanied by some polymer deposition. The polymer deposition was estimated using a shadowing technique, whereby the polymer deposition is assumed to be isotropic. An overhanging structure consisting of two overlapping silicon wafers was used and the thickness of polymer deposited under the overhang (and so shielded from ion bombardment) was measured using surface profilometry. The temperature of the samples was controlled by varying tne thermal contact between the sample 19 and the cooled electrodes eg. 12.
- thermocouple measurements (1) no thermal contact between the sample and the electrode; (n) partial thermal contact through several point contacts of vacuum grease; (m) good thermal contact through vacuum grease spread on the back of the sample. Good thermal contact was used m all experiments where the temperature was held constant and for all photoresist masked samples.
- Etc ⁇ rates The resulting etch rates as a function of RF power (at 13.56 MHz) coupled into the discharge are snown m Fig. 2a for an a-Si mask and m Fig. 2b for a photoresist mask. It is seen that the S ⁇ 0 2 etch rate is slightly higher (around 10 %) m the case of tne a-Si mask for similar power levels. With the a-Si mask the SiO ? etch rate increases by almost a factor of three over the investigated power range reaching a value of 0.8 ⁇ /min at the maximum power. The a- Si etch rate increases witn power faster than the S ⁇ 0 2 etch rate thus causing an overall decrease in selectivity over a- Si from 20:1 to 12:1. Similarly, the selectivity over photoresist also decreases with the power.
- Etcned profile and dimension loss The etched sidewall slope angle, as a function of power for a-Si and photoresist masks, is shown m Fig. 3a.
- the SEM photographs of the corresponding etched profiles are shown m Figs. 4a to 4h.
- the angle of the profile slope was found to increase with the power, being greater for an a-Si mask for similar power levels.
- Sidewall roughness As illustrated m Fig. 3c, the sidewall roughness appears to be consistently higher for a photoresist mask than for an a-Si mask. In both cases, however, it was found to increase with power and, as can be seen m Fig. 3c, the sidewall roughness for etching with an a-Si mask at the highest power level is comparable witn the sidewall roughness obtained with the photoresist mask at lower power levels.
- Polymer deposition rate The polymer deposition rate m the area shadowed from ion bombardment was found to give results as indicated m Fig. 3d. It was found to increase by about 30 % over the whole power range. Also, it may be noted that at the minimum power, the polymer deposition rate was around 3 times smaller than the S ⁇ 0 2 etcn rate, which means that m ion bombarded areas, during etching of 1 ⁇ m of S ⁇ O, around 0.35 ⁇ m of polymer is simultaneously removed. As the power increases this portion of removed polymer is reduced to around 20 ° or 0.2 um for 1 ⁇ m of S ⁇ 0 2 . The Effect of Q 2 and CF Additions, and Sample Temperature Variation
- etching mechanism As polymer deposition was found to play an important role m the etching mechanism, different methods of controlling it were investigated. These include (1) 0 2 additions, (11) CF 4 additions and, (iii) elevated substrate temperature .
- 5a to 5f has been separated into two components, a vertical component, which is related to the mask thickness decrease, and a lateral component, which is related to the mask width decrease.
- a vertical component which is related to the mask thickness decrease
- a lateral component which is related to the mask width decrease.
- Etched profile As illustrated m Fig. 6a, the slope of the etching profile was found to first increase with temperature and then decrease below the initial value. As shown m Fig. 6b, 0 2 additions caused a small initial increase in the slope followed by a gradual decrease. As illustrated m Fig. 6c, the slope was found to be essentially independent of the CF 4 flow rate. Sidewall roughness. As shown m the sidewall roughness was found to decrease with both temperature (Fig. 6d) and 0. flow (Fig. 6e) but was not effected by the CF 4 (Fig. 6f) . It is seen that the sidewall roughness can be reduced to 0.02 um, either by elevating the sample temperature or by adding 0 2 to the gas mixture.
- Fig. 6d With temperature as a control parameter, minimum sidewall roughness can be achieved while maintaining the anisotropy of the a-Si mask etching.
- 0 2 can also be used to reduce roughness (Fig. 6e) , but the same minimum roughness can only be achieved at the expense of dimension loss, since, at the required 0 ⁇ flow rates, the etching of a-Si becomes essentially isotropic (Fig. 5e) . From a practical point of view this suggests that the sample temperature is a more useful control parameter for reducing sidewall roughness compared to the addition of 0 2 .
- the improvement m the sidewall roughness can be seen in Figs. 7a and 7b, which shows SEM images of two sidewalls etched at different temperatures .
- Polymer deposition rate The polymer deposition rate on a shadowed surface as a function of sample temperature
- Fig. 8 m the case of the etched structures described it is possible to specify four surfaces 31 - 34 on which sucn a film may exist.
- S ⁇ 0 2 surfaces 34 are free of polymer film for RF bias voltages above 100V (at a pressure of 0.13 Pa), and that the threshold bias voltage between polymer etching and deposition decreases with pressure. Therefore, using 12 Pa and 400V - 600V bias, a polymer free S ⁇ 0 2 bottom surface 34 generally results. This is supported by the fact that S ⁇ 0 2 etch rates do not increase vvith polymer suppression, either by 0? additions, or increasing sample.
- a polymer film can be present only on surfaces 31, 32 and 33.
- the polymer on surface 31 determines the etching selectivity, whereas 32 and 33 will effect the etching profile and sidewall roughness.
- the presence of a finite thickness of polymer implies tnat both etching species and reaction products must diffuse tnrough the polymer on their way to or from the etched surface, a mechanism which has previously been suggested by others.
- etching species diffusing through the polymer film have a certain probability of reaction with the polymer, which is proportional to the film thickness. Porosity m the polymer film can contribute to this etching mechanism.
- this "diffusion" etching component also increases, thus increasing the total polymer removal rate and preventing continuos film growth.
- these effects will give rise to a certain equilibrium polymer thickness, which will determine the etch rates of the underlying surfaces.
- ER is the etch rate of the surface under the polymer film
- I ⁇ is the flux of active etching species at the polymer film surface
- ⁇ is the probability of polymer etching oy diffusing active species per unit of film thickness
- d is the thickness of the polymer film
- ER Do:Ly]T er
- er is the polymer etch rate
- C and C 2 are empirical constants
- I is the ion flux
- ⁇ is the sidewall slope or effective ion angle of incidence, , E, > ⁇ ) 1S the reactive sputtering yield as a function of active species flux I d , ion energy E and effective ion angle of incidence ⁇ .
- I- is the flux of polymer forming species and ⁇ " is the sticking probability of the polymer forming species as a function of the surface temperature.
- the photoresist, a-Si and SiO? etch rate results of Figs. 2 and 3 can be explained using this model.
- the lateral a-Si etch rate behaves differently for the temperature and 0 cases on one side and CF case on the other (Fig. 5d to Fig. 5f) .
- the lateral etch rate increases, approaching the vertical etch rate, thus indicating isotropic etching of the a-Si mask.
- the lateral a-Si etch rate increase is small and the anisotropy remains unchanged due to a proportional increase the vertical etch rate.
- the difference m vertical ano lateral etch rate of the a-Si mask is due to the different steady-state polymer film thickness on its top surface and sidewalls.
- the sidewalls receive less ion bombardment during etching which, according to Eq. 2, reduces the reactive sputtering component of polymer etching and causes an increase in its steady-state thickness to the point where lateral etching of the mask ceases, as seen in the first few points in Fig. 5d to Fig. 5f.
- the increasing lateral etch rate with temperature and 0 2 additions is due to a reduction m polymer thickness on the sidewalls. In the temperature case, this can be attributed to reduced polymer deposition Fig. 6g.
- a sloped profile m silica a material with known intrinsically anisotropic etching characteristics may be produced m two ways.
- the considerable dimension loss observed when using a photoresist mask (Fig. 3b) suggests that mask erosion is the cause of the sloped profile m this case.
- the etching rate of the sidewall polymer will depend on the slope ( ⁇ m Eq. 2) .
- the etched profile observed using an a-Si mask is seen to be "overcut" (Fig. 3b and Fig. 9a to Fig. 9c) .
- the effect of higher power is to increase the reactive sputtering component of polymer etching due to higher ion energy and density.
- the polymer depositior rate decreases only slightly but its reactive sputtering rate increases due to active oxygen produced in the discharge thus increasing the equilibrium sidewall angle. Further increases in temperature and 0 flow cause total polymer removal from the sidewalls of the a-Si mask, resulting m lateral etching of the a-Si and a smaller sidewall angle due to mask erosion.
- the sidewall slope is relatively independent of CF 4 additions, which indicates that the increase m polymer deposition rate due to CF flow is balanced by the simultaneous increase in its etching rate, prodably due to an increase m the fluorine flux.
- Fig. 11a shows a etched sidewall with a photoresist masK still place. It is seen that roughness has been generated in the photoresist during the process and then transferred to the silica sidewall where the mask edge has been thinned by the faceting which is evident.
- the increase silica sidewall roughness with power can be explained by an increase micromaskmg as both ion bombardment and polymer deposition rate increase.
- Fig. lib shows an etched sidewall with the a-Si mask still place.
- the upper part of the sidewall close to the mask is smoother than the lower part, suggesting that a larger part of the roughness has not been transferred from the mask edge, but rather has formed on the sidewall during etching.
- the reason for this additional roughness is likely to be the sidewall polymer which can act as a micromaskmg material.
- the sidewall roughness increase with power can be explained by an increase m micromaskmg, this case both the masK edge and the sidewall itself, as both ion bombardment and polymer deposition rate increase.
- sample temperature as a control parameter allows smooth sidewalls to be obtained without dimensional loss, wnereas using O t additions does not allow for a process window where both dimension control and smooth sidewalls can be achieved.
- active oxygen enhances the polymer etching rate on both the a-Si mask and SiO sidewalls and therefore, together with an improvement is sidewall roughness, it brings about dimension loss due to isotropic etching of the mask.
- the flux of polymer forming species from the plasma remains unchanged, but their sticking probability is reduced, thus decreasing the effective polymer deposition rate, which then results in reduced roughness.
- the model is based on a balance between isotropic polymer deposition and etching.
- a polymer film of a certain steady-state thickness is formed as a result of this balance on (l) the top surface of the mask, (n) the sidewalls of the mask and (m) the sidewalls of the SiO ⁇ .
- the polymer thickness on the top surface determines the etching selectivity, whereas the polymer thickness on the mask sidewalls and SiC sidewalls determines the profile slope and sidewall roughness.
- the silica reactive ion etching process of the preferred embodiment satisfies all the requirements of planar waveguide fabrication and can also be used for other integrated optics applications or MEMS applications where deep etching of silica is required along with smooth etched sidewalls and vertical or sloped etching profiles. It would be appreciated by a person skilled the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered all respects to be illustrative and not restrictive.
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Abstract
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Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10517017A JP2001501573A (en) | 1996-10-04 | 1997-10-03 | Reactive ion etching of silica structures |
EP97942702A EP0968142A4 (en) | 1996-10-04 | 1997-10-03 | Reactive ion etching of silica structures |
AU44448/97A AU724044B2 (en) | 1996-10-04 | 1997-10-03 | Reactive ion etching of silica structures |
CA002265617A CA2265617A1 (en) | 1996-10-04 | 1997-10-03 | Reactive ion etching of silica structures |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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AUPO2818 | 1996-10-04 | ||
AUPO2818A AUPO281896A0 (en) | 1996-10-04 | 1996-10-04 | Reactive ion etching of silica structures for integrated optics applications |
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Publication Number | Publication Date |
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WO1998015504A1 true WO1998015504A1 (en) | 1998-04-16 |
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PCT/AU1997/000663 WO1998015504A1 (en) | 1996-10-04 | 1997-10-03 | Reactive ion etching of silica structures |
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US (1) | US20020104821A1 (en) |
EP (1) | EP0968142A4 (en) |
JP (1) | JP2001501573A (en) |
KR (1) | KR20000048865A (en) |
AU (1) | AUPO281896A0 (en) |
CA (1) | CA2265617A1 (en) |
WO (1) | WO1998015504A1 (en) |
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WO2002088787A2 (en) * | 2001-04-27 | 2002-11-07 | Lightcross, Inc. | Formation of an optical component having smooth sidewalls |
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WO2006135098A1 (en) * | 2005-06-14 | 2006-12-21 | Asahi Glass Co., Ltd. | Method of finishing pre-polished glass substrate surface |
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EP3839650A1 (en) | 2019-12-18 | 2021-06-23 | ETA SA Manufacture Horlogère Suisse | Method for manufacturing at least two mechanical parts |
EP3839648A1 (en) | 2019-12-18 | 2021-06-23 | ETA SA Manufacture Horlogère Suisse | Method for manufacturing a mechanical part provided with a magnetic functional area |
US11649412B2 (en) | 2019-12-18 | 2023-05-16 | Eta Sa Manufacture Horlogère Suisse | Method for manufacturing a mechanical timepiece part provided with a magnetic functional area |
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Also Published As
Publication number | Publication date |
---|---|
AUPO281896A0 (en) | 1996-10-31 |
EP0968142A4 (en) | 2003-08-06 |
US20020104821A1 (en) | 2002-08-08 |
JP2001501573A (en) | 2001-02-06 |
EP0968142A1 (en) | 2000-01-05 |
KR20000048865A (en) | 2000-07-25 |
CA2265617A1 (en) | 1998-04-16 |
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