WO2001027574A1

WO2001027574A1 - Apparatus and method for infrared radiation transmission and system and method for infrared analysis

Info

Publication number: WO2001027574A1
Application number: PCT/CA2000/001176
Authority: WO
Inventors: Thomas Whidden; Sun Young Lee; Xiaoyi Bao; Ping Lu; James H. Taylor; Zhao Xiaozhong; Michel Couturier; Sébastien ROMET; Donald Hornibrook
Original assignee: Prosensys, Inc.
Priority date: 1999-10-08
Filing date: 2000-10-06
Publication date: 2001-04-19
Also published as: AU7637300A

Abstract

The invention relates to an apparatus for infrared radiation transmission, primarily in the mid-infrared spectrum. The system comprises a mirrored ellipsoidal cavity which collects infrared radiation from a source such as a glowbar, a silicon carbide element or an infrared laser diode. The collected radiation is directed to an interferometer such as Michaelson interferometer as used in FT-IR. An output beam is directed to a fiber bundle having a symmetrical array of optical fibers including silver halide in combination with zirconium fluoride and/or silica fibers. The fiber bundle provides high broadband mid-infrared energy transmission. A system for infrared analysis of a fluid is disclosed additionally comprising a radiation directing means to direct infrared radiation through a sample to be analysed, and to a detector for determining IR radiation directed through the sample. The apparatus and system may be used for monitoring and controlling semiconductor device manufacturing processes, such as chemical vapor deposition (CVD) by focussing an infrared probe beam within a gas associated with a CVD reaction chamber.

Description

APPARATUS AND METHOD FOR INFRARED RADIATION

TRANSMISSION AND SYSTEM AND METHOD FOR INFRARED ANALYSIS

The present invention relates to an apparatus for infrared radiation transmission and a method for infrared analysis of a gas liquid solid, or plasma medium

BACKGROUND OF THE LNVENTION

Mid-mfrared electromagnetic radiation is in the range of from 500-5000 cm of the electromagnetic spectrum (wavelengths of 2 0-20 0 μm) Infrared spectroscopy can be used for identification and quantification of chemical species

Fourier transform infrared spectroscopy (FT-IR) involves transmitting a collimated beam from an infrared source into a Michelson interferometer The beam leaving the interferometer is focussed onto a sample region, and further to a detector, commonly a mercury-cadmium-telluπum (MCT) detector Conventional FT-IR arrangements involve optical elements such as curved or flat mirrors positioned near an infrared radiation source to collimate and transmit the infrared radiation emanating from the source into the interferometer U S patent 5,212,748 illustrates conventional FT-IR arrangements employing such optical elements A great deal of infrared radiation emanating from the source is lost and thus does not enter the interferometer

Semiconductor device manufacturing processes, such as chemical vapor deposition (CVD), are used for deposition of thin films on a workpiece such as a semiconductor substrate Atmosphenc pressure (APCVD), low-pressure (LPCVD) and plasma-enhanced (PECVD) chemical vapor deposition processes are employed to yield insulators such as silicon dioxide, semiconductors such as polycrystallme silicon, and conducting metal films such as aluminum or tungsten, which exhibit properties appropriate for applications within ultra-large scale integration (TJLSI) device fabrication

Instrument control sub-loops, without feedback control based on process chemistry variables, have conventionally been emplo\ ed for process control of CVD equipment The semiconductor industry demands high yields and consistent quality Thus, in an attempt to improve CVD processes and optimize reaction conditions, realtime (or in situ) feedback control of manufacturing equipment on the basis of process chemistry variables has emerged

An increase in the dielectric constant for storage capacitors is required for the production of sub-0 2 um semiconductor devices Organometallics are suitable starting reagents for high dielectric constant films, and exhibit significant gas phase chemistries in the industrial configurations employed for CVD reactions Since gas phase reaction yields high participate counts, the high risk of gas phase reaction duπng CVD conflicts with the need for stringent particulate control at smaller geometries, particularly sub-0 2 μm semiconductors Real-time monitoring and control of gas phase reactions in the manufacture of semiconductor devices is therefore a necessity

Dielectric films are required to be fully conformal and void-free, and must have low moisture content Conventional processes for forming conformal, void free dielectric films have shown significant problems with moisture content and often result in a film which exhibits a hygroscopic character As well, different gas phase chemistries yield differing degrees of conformal film coating in organometallic based oxide depositions Depending on the dominant intermediate in the gas phase, conformality of the resultant thin film may or may not be acceptable for the deep submicron regime during ultra-large scale integration device fabπcation In order to achieve the necessary characteπstics in oxide films, a means to accurately monitor and control the components and characteπstics of gas phase intermediate species in real-time is required - j -

Real-time monitoring and control techniques have been developed for in situ determination of the thickness of a layer on a workpiece during fabrication of semiconductor devices U S Patent No 5,724 144 (Muller et al , 1998) discloses a process for monitoring the thickness of a semiconductor layer by directing an infrared beam at the back surface of the workpiece, and detecting reflections from the front and back surfaces within a chemical vapor deposition chamber U S Patent No 5,403,433 (Morrison et al , 1995) describes a method for in situ determination ot temperature and optical constants of a substrate surface through FT-IR measurement of infrared radiance, reflectance and transmittance However, these documents do not address the effect of spectral losses in the mid-mfrared range associated with conventional FT-IR spectroscopy

U S Patent No 5,431,734 (Chapple-Sokol et al , 1995) discloses an apparatus for real-time monitoring of reactant vapors for contaminants prior to delivery of the reactant vapor to a CVD reaction chamber Conventional FT-IR is used to detect chemical species within a gas sample prior to introduction into the CVD chamber However, this work does not address either the sensing of the reactant vapors withm the CVD chamber or control of the relative concentrations of these vapor withm the chamber during the CVD process

U S Patent No 5,534,066 (O'Neill et al , 1996) teaches a fluid delivery apparatus for monitoring reaction chamber conditions and control processing of a semiconductor wafer within a CVD reaction chamber An infrared sensor is used to determine the concentration of a component of the input fluid in the reaction chamber by sending an infrared beam through the fluid withm the chamber to a detector The detector produces an electrical output signal indicative of the amount of radiation received Fluid delivery into the chamber is adjusted in real time on the basis of the data obtained However, this work does not address control of the relative concentrations of these vapor within the chamber during the CVD process Hanaoka et al (Jpn J Appl Phys 1993 32 4774-4778 and Thin Solid Films 1995 262 209-217) teach in situ measurement ot gas-phase reactions during CVD processing using

FT-IR detection of gas-phase species The FT-IR apparatus is located adjacent the CVD chamber However, no application is disclosed which would allow remote detection of the infrared beam through fiber optic transmission

U S Patent No 5,536 359 (Kawada et al , 1996) teaches a semiconductor device manufacturing apparatus which evaluates contamination within a manufacturing chamber using infrared radiation detection A quartz rod is used to insert IR electromagnetic radiation into the chamber The use of a conventional hollow waveguide optical fiber is disclosed for transmission of infrared radiation However the loss of signal intensity associated with launching infrared radiation into a fiber is not addressed The sensitivity of the spectral analysis suffers due to such intensity losses and solutions to this problem are needed for real-time analysis and control to be practicable

Fiber optic mid-infrared radiation transmission conventionally employs chalcogemde glass fibers The chalcogemdes comprise oxygen, sulfur, selenium, tellurium and polomum Typical chalcogenide glass fibers include arsenic sulfide, arsenic germanium selenide, germanium selenium tellurium, or germanium arsenic selenium tellurium Chalcogemde fiber is inadequate for transmission of frequencies below about 1300 cm ^l due to spectral losses in the chalcogenide fiber in this frequency range Heavy metal fluoride glass (HMFG) fibers, such as zirconium fluoride fibers, are conventionally used for transmission of extended near-infrared radiation (frequencies of 10,000-2200 cm ^l, wavelengths of 1 0-4 5 μm) Below frequencies of about 3000 cm \ zircomum fluoride fibers exhibit spectral losses which decreases sensitivity in this range U S Patent No 4,521 ,073 (Murakami et al ) discloses infrared radiation transmitting fibers prepared from various crystalline materials However, no fiber bundle is disclosed that optimizes - 0 the transmission of infrared radiation, especially in the mid-infrared region of from

500-1500 cm

Fiber bundles are often combined with epoxv or other adhesives to support the position and orientation of different fibers withm the bundle Such fixatives are acceptable m spectroscopic applications m which chalcogenide fibers are employed since the chalcogenide fiber has a protective cladding layer In the case of silver halide fibers, however, suitable protective claddings that do not react with the fiber are not currently available and the presence of an epoxy fixative is detrimental to their use in spectroscopic applications When the epoxy is in direct contact with the fiber surface, discrete frequencies of the mid-mfrared radiation are strongly absorbed and such absorptions degrade the uniform broadband sensitivity required for quantitative spectroscopic analyses

U S Patent No 5,402,508 (O'Rourke et al ) discloses a fiber optic probe having transmitting and receiving fibers in a bundle The fibers are maintained in place using epoxy in combination with carbon black, a radiation absorber, to reduce crosstalk between the various fibers U S Patent No 5,239, 176 (Stevenson) discloses an optical fiber formed of chalcogenide glass for use as a multiple internal reflection sensor transmitting infrared radiation U S Patent No 5,569,923 discloses a single fiber optic probe (as opposed to a multiple fiber bundle) for infrared spectroscopy having input and output optical fibers formed of chalcogenide glass, fluoride glass or polycrystallme silver halide glass However, spectral losses at particular wavelengths are not addressed in any of these documents

IR Link™ Fiberoptic Cables (http //www galileocorp com/detector/ spectroscopy/ιr_fιber_cables htm, 1999) offers spectroscopy grade single and multi- fiber cables for industrial process infrared applications Only chalcogemde cables are offered for use with mid-mfrared applications Fiber bundle connectors are conventionally constructed of stainless steel or other metals which may react with certain metal-containing optical fibers, such as silver halide fibers. Such reactions would eventually damage the fiber. Additionally, most connectors are designed to connect fiber bundles having fibers which are oriented securely with adhesives within the fiber bundle. Connectors which employ frictional engagement of a fiber are known in the art, for example as disclosed in International Patent Application No. PCT/US97/ 12340, published January 22, 1998 as publication WO 98/02767. Also, ordinary connectors are designed for only one fiber dimension, not for multiple fiber bundles.

The prior art does not address the energy loss of the IR signal, for example the losses associated with capturing the IR at launch and losses within the optic fiber during transmission due to reflection and non specific absoφtion. This is important as with a reduction in the intensity of the IR signal, the sensitivity of an IR based instrument is reduced for example during sampling, or other desired applications.

It is an object of the invention to provide an apparatus and method for infrared radiation transmission, a system and method for infrared analysis of a solid, liquid, gas or plasma, particularly for monitoring a semiconductor device processing chamber, a fiber bundle for infrared radiation transmission, and a fiber bundle connector assembly which overcomes the above-noted deficiencies of the prior art.

SUMMARY OF THE INVENTION

According to the invention, there is provided an apparatus for infrared beam transmission comprising: a mirrored ellipsoidal cavity surrounding an infrared radiation source for collecting infrared radiation from the source, an interferometer for receiving infrared radiation and producing an output beam; a fiber bundle for transmitting the output radiation beam; a first optical element for directing infrared radiation collected by the mirrored ellipsoidal cavity to the interferometer; and a second optical element for directing the output beam from the interferometer to the fiber bundle.

Advantageously, the mirrored elliptical cavity increases the intensity of the output radiation beam, thereby compensating for launch and transmission losses associated with fiber optic transmission. This permits the system of the present invention to transmit the IR beam with improved sensitivity in the mid-infrared spectrum. Intensity losses are further reduced by the absence of adhesives in the radiation conducting fiber bundle.

As a further advantage, the apparatus according to the invention permits transmission of mid-infrared radiation, without significant spectral peπurbations over long distances.

The invention also provides a method for infrared radiation transmission comprising the steps of: collecting infrared radiation from an infrared radiation source within a mirrored ellipsoidal cavity; directing collected infrared radiation to an interferometer; producing an infrared output beam from the interferometer; and transmitting the output beam through a fiber bundle.

A system for infrared analysis of a solid, liquid, gas or plasma comprising the apparatus according to the invention, an radiation beam directing means in optical communication with the fiber bundle, for directing the output beam through the fluid; and a detector in optical communication with the radiation beam directing means, for determining infrared radiation directed through the fluid.

Advantageously, the system according to the invention permits monitoring of an infrared absorbing species in a solid, liquid, gas or plasma, based on the transmission or reflection of infrared radiation through the solid, liquid, gas or plasma. The system has a high signal intensity in the mid-infrared region. In a particular embodiment of the system, gases in association with a semiconductor device processing chamber are monitored and the results are assessed in real-time to determine if changes in chamber conditions are required, thereby allowing feedback control m the processing of semiconductor devices

The invention additionally comprises a method for infrared analysis of a fluid comprising the steps of collecting infrared radiation from an infrared radiation source within a mirrored ellipsoidal cavity, directing collected infrared radiation to an interferometer, producing an infrared output beam from the interferometer, transmitting the output radiation beam through a fiber bundle to the fluid, directing the output beam through the fluid to a detector to determine perturbations in the infrared radiation directed through the fluid

Further, according to the invention, there is provided a fiber bundle for transmitting infrared radiation beams, comprising one or more silver halide fibers and a plurality of heavy metal fluoride glass fibers arranged symmetrically withm a bundle sheath

Advantageously, the fiber bundle according to the invention permits mid- lnfrared radiation transmission with minimum loss of signal, particularly for frequencies below 1300 cm^"1 Advantageously, the fiber bundle is adhesive-free, which prevents infrared radiation absorption by an adhesive

According to another aspect of the invention, there is provided a fiber bundle connector comprising a male housing and a female housing The male housing comprises a first end and a second end, a bore extending from the first end to the second end capable of receiving a fiber bundle, the first end having radially compressible fmgers for fπctionally engaging a fiber bundle received within the bore The male housing comprises screw threads on an external surface thereof, and the second end is optionally attachable to a bundle sheath The female housing comprises a first end and a second end, a bore extending from the first end to the second end, a receiving cavity disposed at the first end being adapted to receive and radially compress the radially compressible fingers of the male housing, the housing of the female receiving cavity comprising screw threads on an internal surface thereof adapted to mate with the screw threads of the male housing, and attachment means to connect the female housing to a radiation transferring element The mating of the screw threads of the finger housing with the screw threads of the receiving cavity housing radially compresses the fingers to fπctionally engage a fiber bundle withm the bore of said male housing Advantageously, the connector assembly allows orientation and alignment of fibers withm a bundle using factional engagement, thereby negating the need for adhesr e withm a fiber bundle when connected to other fibers

The ellipsoidal cavity and launching optics of the proposed invention are more cost effective than other IR radiation sources such as the IR diode laser While the IR diode laser produces a high intensity of IR radiation, these sources are not yet tunable to the wavelengths required for broadband transmission of mid infrared frequency

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings wherein

FIGURE 1 is a schematic representation of an apparatus for infrared radiation transmission according to an embodiment of the invention, FIGURE 2 is a schematic representation of apparatus for infrared beam transmission according to an embodiment of the invention having a fiber bundle transmitting an infrared beam from the mirrored ellipsoidal cavity to a parabolic mirror prior to entry into the interferometer,

FIGURE 3 a) is a cross-sectional view of a fiber bundle comprising silver halide and zirconium fluoride according to an embodiment of the invention, b) is the transmission loss spectrum for the silver halide fibers; c) is the transmission loss spectrum for the zirconium fluoride fibers;

FIGURE 4 a) is a cross-sectional view of a fiber bundle comprising silver halide, zirconium fluoride, and silica fiber according to an embodiment of the invention; b) is a cross-sectional view of alternate fiber bundle arrangements according to embodiments of the invention.

FIGURE 5 is a side view in section of a fiber bundle connector according to an embodiment of the invention illustrating the male housing (a) and the female housing (b) and the union thereof (c); FIGURE 6 is an end view along line A-A of the male housing (a) of the connector of FIGURE 5;

FIGURE 7 is a side view in section of the fiber bundle of FIGURE 3 a connected at each end to a conventional optical fiber bundle using the connector of FIGURE 5; FIGURE 8 is side view in section of an embodiment of the invention for use as a broadband multiple internal reflectance probe for liquid analysis;

FIGURE 9 a) is a schematic representation of a system for monitoring gases in a semiconductor device processing chamber according to an embodiment of the invention, having an infrared beam directed through the reaction chamber above a substrate; b) is a representation of a similar system as described above except that the infrared beam is transmitted through the medium several times before reaching a detector

FIGURE 10 is a schematic representation of a system for monitoring gases associated with a semiconductor device processing reaction chamber according to an embodiment of the invention, having an infrared beam focussed through an exhaust stream of gas derived from the reaction chamber;

FIGURE 11 is a schematic representation of a system for monitoring gases in multiple semiconductor device processing chambers according to an embodiment of the invention; FIGURE 12 illustrates differences in mid-infrared radiation collection using the apparatus according to the invention as compared with a conventional FT-IR spectrometer (SiC IR source (•), glowbar element (A) and glowbar/double mirror

(■)),

FIGURE 13 illustrates the effect of radiation source on infrared beam focal spot intensity and size using ellipsoidal cavity IR collection (glowbar source (♦) and circular SiC source (■)),

FIGURE 14 illustrates the mid-mfrared radiation spectrum transmitted using a chalcogenide optical fiber (a) versus the mid-mfrared radiation spectrum transmitted by one of the fiber bundles of the present invention (b) The upper curve (ii) (in Figure 4b) represents the transmission spectrum with the ellipsoidal cavity in place versus the lower curve (I) (in Figure 4b) which represents the transmission spectrum without the cavity

FIGURE 15 illustrates the infrared spectrum of tetraethoxysilane (TEOS) as determined by (a) conventional FT-IR sampling and (b) infrared spectroscopy using the fiber bundle according to the invention, but without the ellipsoidal collector; FIGURE 16 illustrates in situ infrared spectra obtained using a system according to an embodiment of the invention, showing starting materials used in CND processing of sihcone dioxide thin films obtained according to the invention of (a) TEOS in gas phase at 300°C, (b) ozone under process conditions, and (c) gas phase reactants in the TEOS/ozone process, FIGURE 17 presents data obtained by a system according to the invention showing (a) the correlation of TEOS absorption at 794 cm with vapor pressure of TEOS m a CND reactor, and (b) partial pressure of TEOS in the presence of diluent gasses within a semiconductor device processing chamber,

FIGURE 18 presents data obtained by a system according to the invention showing a correlation of Sι0₂ deposition with the 1117 cm peak region in the gas phase TEOS/ozone CVD process,

FIGURE 19 presents data obtained using a system according to the invention showing a correlation of SιO₂ hydroxyl content within the 1061 cm ¹ peak region m the gas phase TEOS/ozone CVD process, FIGURE 20 illustrates a real-time closed-loop control of infrared peak intensities during a CVD reaction DESCRIPTION OF PREFERRED EMBODIMENTS

The apparatus according to the invention is used for infrared radiation transmission, particularly to direct infrared radiation from a source through to an output beam that may be useful for a variety of .analytical applications.

As used herein, the phrase "in optical communication with" is used to refer to elements of the invention between which infrared radiation is capable of being directed.

With reference to the figure 1 , the apparatus of the present invention exhibits similarities to a conventional Fourier transform infrared (FT-IR) spectrometer, except that in a preferred embodiment as described herein the IR radiation is collected by a miπored ellipsoidal cavity (10) surrounding the infrared radiation source (20). The mirrored ellipsoidal cavity (10) serves to collect a high percentage of the available infrared radiation (30) from a source (20). The presence of the mirrored ellipsoidal cavity (10) allows capture of an increased quantity of infrared radiation (30) from the source, some of which would normally escape collection, thereby creating a stronger beam to direct into an interferometer (40).

While the mirrored ellipsoidal cavity of the proposed invention may be used in combination with an IR radiation source, such as a glowbar element or a SiC IR element, a collimated IR radiation beam, effected by the use of an IR diode laser as an IR radiation source, either alone or in combination with a mirrored ellipsoidal cavity is also contemplated by the proposed invention.

The mirrored ellipsoidal cavity (10) may be of any appropriate dimension to surround an infrared radiation source (20) while leaving an opening for the radiation (30) so collected to be transferred As shown in Figures 1 , 2, and 9-11 the infrared radiation beam source (20) is placed at the ellipsoid focal point withm the mirrored ellipsoidal cavity (10) so that most energy emanating therefrom is collected

Conventional interferometers (40) may be used in the apparatus, such as the Michaelson interferometer, which is standard in FT-IR spectroscopy

Infrared radiation for transmission using the invented apparatus may be of am wavelength in the infrared range The invention is particularly suited for mid-mfrared radiation, having a frequency of 500 - 5000 cm^{" 1} in the mid-mfrared region of the electromagnetic spectmm Because the mirrored ellipsoidal cavity (10) collects a maximum amount of radiation from the infrared radiation source (20), a stronger infrared beam is transmitted with the apparatus than is transmitted in conventional FT-IR configurations (see Figure 12)

The infrared energy source (20) is typically a blackbody radiation source for mid-mfrared radiation Without wishing to be limiting, a glowbar, IR laser diode or silicon carbide (SiC) element of different geometry may be used as an infrared radiation source (20) By incorporating a cylindrical silicon carbide source in the apparatus according to the invention, an increase of up to 4-fold in the total optical power of mid-mfrared radiation beam transmitted is achieved, when compared to the use of a glowbar source As illustrated by the data presented in Figures 12 and 13, and discussed m more detail below, the focal spot size and shape is optimized when using small circular SiC elements as an radiation source

An output radiation beam (50) exits from the interferometer (40) and is launched (80) into a transmitting fiber bundle (60, e g Figure 9a) having a high transmission for infrared radiation Preferably, the fiber bundle will have high transmission m the 500 - 5000 cm^{" 1} (mid-mfrared) region of the electromagnetic spectrum The apparatus according to the invention comprises a first optical element (70) for directing an radiation beam from the miπored ellipsoidal cavity ( 10) to the interferometer (40). A second optical element (80) is employed for directing the outgoing radiation beam (50) between the interferometer (40) and the fiber bundle (60; e.g. Figure 9a). By optical elements, it is meant any element capable of directing electromagnetic radiation from one point to another without causing considerable loss or random scatter of radiation. Without being limited to the following examples, possible optical elements for use with the invention include mirrors, such as convex or parabolic minors, beam splitters, lenses, optical fibers, fiber bundles, and combinations thereof. Any such optical element as is known in the art may be employed to direct radiation within the apparatus.

According to an embodiment of the invention shown in Figure 1, the first optical element (70) comprises a parabolic minor (75) situated so as to place its focus (100) coincident with the second focal point (105) of the ellipsoidal optical cavity (10) so as to collect and collimate the infrared radiation emanating from the cavity (10). The mirror directs the collimated beam into the interferometer (40). Optionally, to allow the mirrored ellipsoidal cavity (10) to be located remotely from the interferometer (40), or for the use of one radiation source (20) for more than one interferometer (40) , an infrared radiation transmitting fiber bundle (90) may be employed to transmit an radiation beam from the second focal point of the mirrored ellipsoidal cavity (105) to the focus (100) of the parabolic mirror (75), or other optical element, prior to entry into the interferometer (40), for example as shown in Figure 2.

When a fiber bundle (90) is used to transmit IR radiation (30) from the mirrored ellipsoidal cavity (10), the electromagnetic radiation (30) so transmitted can act as a pseudo-point source of infrared radiation. As shown in Figure 2, the optical fiber (90) is placed at the focal point (100) of a parabolic mirror (75), in a configuration which would be difficult to achieve without fiber bundle transmission. As discussed further herein below, the location of the pseudo point source at the focal point (100) of the parabolic mirror (75) improves the transmission characteristics of the infrared output beam (50) through the interferometer (40)

An output beam (50) is directed to a fiber bundle (60) from the interferometer by the second optical element (80, Figure 9a), which may comprise any of the optical elements as noted above The fiber bundle may comprise any infrared radiation transmitting fiber bundle, and preferably transmits energy m the mid-mfrared radiation range, from about 500 cm ' to about 5000 cm ^l The fiber bundle (60) for transmitting the output beam (50) may be the same or different from the fiber bundle (90) which may be used to transmit energy to or from the first or second optical element

Several different fiber bundles which may advantageously be used with the apparatus according to the invention are disclosed herein Preferably, the fiber bundle compπses one or more silver halide fibers (110) and one or more heavy metal fluoride glass fibers (120) arranged symmetrically within a bundle sheath (130, Figures 3a and 4) Examples, which are not to be considered limiting m any manner, of such fiber bundles having a symmetrical arrangement of fibers are shown m cross section m Figures 3a and 4 However, it is to be understood that any fiber bundle capable of transmitting between 500 cm ' and 5000 cm ¹ may be used for the purposes disclosed herein

The fiber bundle (60) of the present invention comprise fibers that transmit IR of about 500 to about 6000 cm ' For example, which is not to be considered limiting, silver halide may be used to transmit from about 500 to 2000 cm ^l (Figure 3b) and heavy metal fluoride fiber to transmit from about 2000 to about 6000 cm ¹ (Figure 3c) Additionally, the inclusion of silica fibers (140) m the bundle (Figure 4) extends the useful wavelengths that the fiber bundle can effectively transmit into the near infrared and visible regions of the spectrum This latter property of silica fiber contaimng bundles can prove very useful during alignment of the optical system Any silver halide fiber may also be used for the transmission of IR over 500 cm ^! and 5000 cm ^l, for example, but not to be construed as limiting, fibers having Br or Cl as the halide may be used, such as AgBrCl fibers One or more silver halide fibers (110) may be used in the fiber bundle (60 and 90) However, m the preferred embodiment, the arrangement of the silver halide fibers (110) in the fiber bundle (60 and 90) is symmetrical A symmetrical arrangement is preferred because the focal point of a typical beam launching mirror (e g (105), Figure 2, or (107), Figure 9a, 10, 11) may be relatively large and multiple fibers are often used to increase the radiation collecting ratio Mid-mfrared radiation is not visible and, since it is hard to see the focal spot, a symmetric configuration of the system makes alignment of the system easier

The fiber bundle (60 and 90) also comprises one or more of symmetrically arranged heavy metal fluoride glass fibers (120) As shown in the cross-sectional view of Figures 3a and 4, a plurality of heavy metal fluoride glass fibers (120) maybe arranged on either side of one or more silver halide fibers (110) However, other configurations may also be employed providing that the desired IR energy is transmitted with minimal loss As an example of a heavy metal fluoride glass, not to be construed as limiting, zirconium fluoride fibers may be used Optionally, a plurality of symmetrically arranged silica fibers (140) may be included in the fiber bundle.

The fiber bundle may comprise a bundle sheath (130), as shown in Figures 3 and 4 The bundle sheath is advantageously formed of a material that is non- reactive with silver halide, for example Teflon^® According to an embodiment of the invention wherein the fiber bundle (60) is used as a probe for broadband multiple internal reflectance liquid analysis (see Figure 8), the bundle sheath (130) is interrupted by an opening (155) through which the fibers extend, or alternatively, the sheath (130) is absent This embodiment is discussed m further detail below

The fiber bundle is essentially adhesive-free Adhesives are conventionally used m fiber bundles to maintain positional alignment between the fibers, particularly at the terminal ends of a fiber However adhesives absorb radiation from fibers, particularly at certain mid-mfrared wavelengths, which alters the radiation transmitted by a fiber bundle Depending on the length of a fiber bundle the amount of energy absorbed by the adhesive could provide faulty data regarding energy absorption by a sample, or could decrease the sensitivity of readings at particular wavelengths The absence of adhesive in the fiber bundle overcomes this draw-back of conventional fiber bundles In order to maintain alignment of the fibers with a bundle, particularly at bundle ends, a fiber bundle connector (180) is disclosed m further detail below

The fiber bundle (60) according to the present invention is not only for use with the apparatus for infrared radiation transmission as described above The fiber bundle may be used in any application wherein transmission of infrared radiation, paπicularly in the mid-infrared range, is required For example, infrared radiation from an LED or infrared diode laser may be used, and the beam output therefrom would be similarly transmitted via an optical fiber or fiber bundle

If a fiber bundle (60) is to be used as an optical element, the fiber bundle (60) of the present invention is advantageously employed to ensure high intensity of IR beam signal, and to provide a pseudo-point source which may be placed at the focal point (100) of a convex or parabolic mirror (75) prior to directing radiation into the interferometer (40)

The present invention also relates to a method for infrared radiation transmission The method comprises the step of collecting infrared energy from an infrared source (20), for example by placing an infrared radiation source within the mirrored ellipsoidal cavity (10) The collected infrared energy (30) is then directed to an interferometer (40), using the first optical element (70), as described above and an infrared output beam (50) is produced The output IR beam (50) is transmitted through a fiber bundle (60), which includes admitting the IR radiation (30) into the fiber bundle at 107 (e g Figures 9a 10) via the second optical element (80), as described above

The apparatus of the present invention may be used with a system for infrared analysis of a solid, liquid, gas, or plasma Analysis of a fluid refers to collecting data with regard to the compositional nature of that fluid, for example the components present in the gas, liquid or plasma, and/or the concentration of a given component A fluid may be any flowable medium through which infrared radiation may be transmitted Examples of applications of the system for either gas or liquid analysis are described below Alternatively, the application may also be used for infrared analysis of a solid As an example, and not to be construed as limiting, the apparatus may be used to measure the thickness of a semiconductor body from an interference signal representative of interference fringes generated from primary and secondary reflections formed when the infrared beam is reflected from the front and back sides of a semiconductor body

The present invention also relates to a system for infrared analysis of a fluid (150), as shown m Figure 8, or a gas (158), as shown m Figure 9a, and Figure 10, comprising the apparatus for infrared radiation transmission as described above The apparatus provides an output beam (160) emanating from the fiber bundle, which is then directed through a fluid (150, Figure 8) or a gas (158, Figure 9a, 10) to be analysed As the IR radiation passes through the fluid, particular characteristics of the IR beam change, depending on the chemical nature and quantity of the species present m the fluid, in keeping with the principles of infrared spectroscopy

As an example of the system with application to liquid analysis, the fiber bundle may be used as a probe for broadband multiple internal reflectance analysis As illustrated m Figure 8, an infrared beam (170) output from the apparatus as described herein is transmitted to a probe fiber bundle which comprises an unsheathed portion (155) This unsheathed portion comprises a "bare" bundle of one or more silver halide fibers (110, Figures 3a and 4) and a plurality of heavy metal fluoride glass fibers (120, Figures 3a and 4) symmetrically arranged, and optionally comprising symmetrically arranged silica fibers (140). The unsheathed portion (155) of the fiber bundle is sealed into a liquid volume (150) to be sampled The seal may be independent bulkhead pressure fittings, a stand-alone probe housing containing both input and output fiber bundle assemblies or any other configuration that fixes the relative positions of the fiber bundles. Without wishing to be limiting, the fiber bundle connector (180), as illustrated in Figures 5 and 6, and as described below in further detail may be used to connect the fiber bundles to a number of components of the probe system, for example, the housing of an optical element, a CVD chamber (200), an input or output transfer element (210 and 220, respectively) or a detector (230).

In this application, as shown in Figure 8, the IR radiation beam (170) is transmitted through the unsheathed portion of the fiber bundle (155), a quantity of energy is absorbed by the liquid medium (150), thereby altering the nature of the beam which is then directed to the detector (230). On the basis of the energy absorbed by the liquid medium, the composition of the liquid medium (150) can be analysed.

The present invention also relates to the analysis of gaseous fluids. Analysis of gas (158) within a semiconductor device processing chamber (200) is discussed herein below (depicted in Figures 9-11). There are various types of semiconductor processing devices that could be monitored using the system and method of the proposed invention. These processes include, but are not limited to, low pressure chemical vapour deposition (LPCVD), atmospheric pressure chemical vapour deposition (APCVD), sub-atmospheric pressure chemical vapour deposition (SAPCVD), plasma and remote plasma enhanced chemical vapour deposition (PECVD and RPECVD), photolytically enhanced chemical vapour deposition (PCVD) and various forms of thin layer etching processes commonly employed in the semiconductor industry. As an example of such processes, chemical vapor deposition (CVD) is discussed herein, however it is to be understood that any such processes having gas or liquid reactants could be monitored according to the invention. Thus, the invention is not limited to the embodiments disclosed. For example, and not to be considered limiting, the proposed invention could be implemented in areas of medicine in which IR or FTIR spectroscopy is used to study, monitor processes and/or identify compounds. Similarly, the proposed invention may be implemented in numerous other chemical areas for example, petroleum processing and refining.

In a single wafer processing module of a CVD chamber (200; e.g. Figure 9a), an input transfer element (210) inputs infrared radiation from the output beam (50) through a gas (158) associated with the reaction chamber (200). The beam (160) traversing the gas (158) is then directed to an output transfer element (220), which then directs it to a detector (230). The gas composition is determined using infrared Fourier transform analysis of the signal from the detector (230), obtaining spectral data that can be used to either quantify or analyse the composition of gasses.

According to one embodiment as described below, gas composition is determined by focussing the infrared beam directly above the substrate (240) surface within a CVD chamber (200), as shown in Figures 9 and 1 1. An infrared probe may alternatively be used to determine the gas composition in a stream or sample of exhaust gasses (158) emanating from a CVD reaction chamber (Figure 10). In a batch-type CVD chamber, an infrared probe may be used to determine gas composition in the inter- wafer space between substrates.

In the embodiment wherein the gas composition is to be detected within a semiconductor processing chamber, for example a CVD chamber (200), the beam (160) can be directed to a position immediately above a substrate (240), the surface on which chemical vapor deposition reaction is to occur, to detect gas composition at that location. The fiber bundle (60) transmits the output beam (50) to a first beam directing means (250 (withm input transfer element (210))) m optical communication with the fiber bundle (60) The beam directing means (250) directs IR radiation through the CVD chamber (200), and onward to a detector (230)

According to an embodiment of the invention, one or more beam directing means (250 and 260) are located withm input transfer element (210) and an output transfer element (220) In combination, these transfer elements direct the beam ( 160) through the CVD chamber (200) to the detector (230) For example, once the probe beam exits the fiber bundle (60), it is directed and focussed by at least one beam directing means (250 and 260), for example a minor and aperture configuration, which may be of any appropriate type known in the an The beam directing means may comprise a multiplexer as the input transfer element

As illustrated in Figure 9(a), to direct IR radiation through the CVD chamber (200), the beam passes through an input transfer element (210) The beam may be focussed at a point directly above the surface of the substrate The beam may, for example be configured to transit the process chamber and focus on a spot size of 0 5 to 1 0 mm in diameter positioned 2 to 5 mm above the substrate surface (240) in the chamber (200) The radiation beam then exits the CVD chamber (200) to an output transfer element (220) As illustrated in Figure 9b, the optical configuration may be altered to provide multiple passes and focussing of the beam above the substrate surface (240) The multiple focal points (275) may be configured to effectively sample the gas volume over the entire substrate diameter as shown in the Figure 9b The input transfer element (210) and output transfer element (220) may be located withm an inert gas purged minor assembly (280) The inert gas may be any acceptable gas as is known in the art such as nitrogen, argon or xenon The present invention may be used to monitor a plurality of process chambers as depicted in Figure 11

Figure 10 illustrates the embodiment of the invention wherein the composition of gases (158) in an exhaust gas stream (159) emitted from a CVD chamber (200) is to be analysed The output beam is directed into a fiber bundle (60). which then transmits the beam to an inert gas purged input transfer element (210) which launches the probe beam (160) into the exhaust gas stream (159) Optionally, the probe beam ( 160) may be reflected by an inert gas purged minor assembly (280) so as to pass back and forth through the exhaust stream as shown in Figure 9b The minor assembly may be ananged to provide multiple passes of the probe beam through the exhaust gas stream before the beam is transmitted to a vacuum-tight inert gas purged collection output transfer element (220) Similarly, an entry gas may be analysed according to this configuration prior to entry into a CVD chamber

In the embodiment where the gas composition between substrates is to be analysed m a batch-style semiconductor processing reaction chamber, having a plurality of wafers located therein on which the chemical vapor deposition reaction occurs, the output IR beam is earned by the fiber bundle into the CVD chamber through an inert-gas purged housing (280), for example, nitrogen purged The housing may be constructed from quartz or any appropnate metal which is inert to the reaction medium withm the chamber The probe beam exits the fiber bundle and is directed to and focussed through the inter-wafer spaces The probe beam is collected by an inert-gas purged optical coupler housed on the opposite side of the substrate

Regardless of the location of the gas to be analysed, once the beam has passed through the gas to be analysed and is optionally transmitted to an output transfer element (220), the beam is directed to a detector (230) A further fiber bundle can be used to transmit the beam to a remotely located detector (230), such as an FT-IR spectrometer detector, where the beam is spectroscopically analysed Alternatively, the probe beam may be analysed by reflection from an optical grating to an appropnate optical grating detector or analyser Any detector or detection method known in the art may be used in the invention

According to an embodiment of the invention, the system may additionally comprise a feedback control means for adjusting a processing parameter on the - ? ZJ basis of the analysis of a gas When the gas composition with a CVD chamber is analysed, the feedback control means may compnse manual manipulation of a processing parameter, or may comprise an automated control module, capable of controlling one or more processing parameter using iterative adjustments aimed at maintaining pre-determmed conditions withm the CVD chamber

The control module may comprise a computer system which accepts input sensor data on gas composition For the embodiment wherein the gas to be analysed is associated with a CVD chamber, the data are compared with pre-established optimal values, and on the basis of comparisons, processing parameters withm the CVD chamber are controlled to achieve or maintain optimal gas composition during the CVD reaction

The computer system comprises appropriate hardware for accepting the analog output of either an FT-IR spectrometer or optical grating detector as input Input signals are digitized and input to software algorithms which first convert the raw signal strength vs wavelength data to a conventional infrared spectrum of the gas phase being analysed The spectral data is input to an algorithm which converts the data to concentration values for individual chemical species which have been previously determined to exist withm the CVD process being analysed These concentration data are then compared with previously determined optimal values specific to the CVD process being analysed Difference in values from the optima are used to calculate new settings for processing parameters withm the semiconductor CVD reaction chamber The updated processing parameter settings are then output to the individual sub-controllers in the processing unit Examples of processing parameters which may be controlled according to the invention include but are not limited to temperature and pressure withm the reaction chamber, and flow rate of reactant gas into the CVD chamber

The cycles of gas composition analysis, spectral conversion, feedback control calculation, and processing parameter setting adjustment are short m duration, and may last from less than 0 1 to 5 seconds thereby allowing iterative real-time adjustment and adaptive control of semiconductor device processing

Advantageously, the invention allows the comparison of real-time gas measurements obtained during a CVD reaction with optimal standard values to allow iterative adjustments to processing parameters during the CVD reaction The iterative adjustments maintain the optimal composition of gas phase elements withm a reaction chamber, thereby promoting fine and reproducible process control and reproducible process control

The parameters evaluated may include concentrations of starting reagents, reactive intermediate species and reaction products during a CVD reaction These values are obtained through the use of a sensor Data obtained from the sensor is input to a control module and conelations with optimum conditions are determined Conditions, or process parameters, such as pressure, temperature and flow rate of reactant gas into the chamber, may then be adjusted to achieve or maintain optimum conditions

The phrase "adjusting a processing parameter ' withm a chamber, refers to manual or automated adjustment of one of the above-noted process parameters

This may be accomplished manually or may be automated, using pre-set values for optimum process conditions withm a chamber

The system gives rise to a method for infrared analysis of a medium According to this method, the infrared radiation from an infrared radiation source withm a mirrored ellipsoidal cavity is collected, as discussed above The collected radiation is directed into an interferometer, and an infrared output beam is produced The output IR beam is transmitted via a fiber bundle through a medium to a detector to determine whether any changes to the infrared beam occurred Determining changes m the infrared beam directed through the fluid may comprise quantifying the amount of radiation and the absorption or transmission of certain wavelengths the of infrared radiation Compositional analysis of the medium through which the beam is directed may be conducted on the basis of changes to the IR radiation beam so determined

The invention further relates to a fiber bundle connector (180) as depicted m

Figures 5, 6, and 7 The connector allows fπctional engagement of the terminal end of the inventive fiber bundle, to maintain the positional alignment of the fibers withm the bundle without the need for adhesives As discussed above, such adhesives may alter infrared radiation transmission by absorbing discrete wavelengths from the radiation transiting the fiber The connector of the present invention allows connection of the fiber bundle described in this invention as well as other bundle configurations to a radiation transferring element, for example, but not wishing to be limiting, the housing of an optical element, a CVD chamber (200), an input or output transfer element (210 and 220 respectively), a detector (230) or an SMA adaptor

The connector (180) of the present invention comprises male (290) and female housings (300) as shown in Figures 5(a) and 5(b), respectively, which fit together The male housing is formed to house the fiber bundle within a bore (310) which extends there through from a first end to a second end

The first end of the male housing (290) is adapted to fit withm the female housing (300) As illustrated in Figure 5(a) and Figure 6, the first end of the male housing comprises a plurality of radially compressible fingers (320), m this case four fingers are shown The fingers have a small space (330) between them which allows inward compression in the radial direction The fingers are arranged around the periphery of the bore (310) through which the fiber extends, thus, when radially compressed, the fingers fπctionally engage the fiber bundle (60), thereby maintaining the positional alignment of the fiber bundle (60) to allow appropriate transmission of the beam In one embodiment of the connector, a fitting comprising an external surface of the male housing (290) has threads located thereon which are specific to the thread-guide of the fittings comprising an external surface of the female housing. The screw threaded surface of the male portion of the housing is adapted to mate with the female portion of the housing (300). As the screw threads of the male and female housings mate, the female housing (300) applies inward pressure on the fingers (320) of the male housing, thereby forcing the fingers (320) radially inward of the central bore (310) to thereby radially compress the fingers, and frictionally engage the fiber bundle (60). However, other fastening means that apply inward pressure on the fingers of the male housing and that mate with the corresponding female housing may also be used, for example snap-fit assemblies.

The optic fibers (65) are inserted into the male portion via the bore (310) which opens to the second end of the male portion (315). This second end of the male portion (315) is optionally attachable to a bundle sheath (130), which may be located around the optic fibers (65). This assists in accomplishing secure attachment of the fiber bundle (60) to the fiber bundle connector (180).

The female housing (300) of the fiber bundle connector (180), as shown in Figure 5(b) comprises a first end (340), a second end (350), and a bore (310) extending therebetween. The first end (340) has a receiving cavity (360) formed therein which is adapted to receive the first end of the male portion. The receiving cavity housing has screw threads on the inner surface of the housing, which are adapted to mate with the screw threads on the housing of the male portion of the connector. However, the receiving cavity (360) is slightly smaller in circumference than the circumference of the fingers (320) of the male portion, which causes compression of the fingers (320) when the male housing portion is screw-threaded into the female hosing portion. However, other fastening means that apply inward pressure on the fingers of the male housing and that mate with the corresponding female housing may also be used, for example snap-fit assemblies. The female portion has an attachment means which allows attachment of the second end of the female housing to a radiation transferring element. The female portion may also comprise a connector nut which attaches to an SMA adaptor.

The male housing is formed of a material which is non-reactive with silver halide, so that the silver halide fibers of the fiber bundle extending therethrough are preserved. An example of such a material would be titanium or gold. The female housing is preferably formed of the same material, but is not necessarily in direct contact with the silver halide fiber-containing fiber bundle, and thus could be made of a compatible but more economical material.

The above description is not intended to limit the claimed invention in any manner, furthermore, the discussed combination of features might not be absolutely necessary for the inventive solution

The present invention will be further illustrated in the following examples.

However, it is to be understood that these examples are for illustrative purposes only, and should not be used to limit the scope of the present invention in any manner.

EXAMPLES

TEOS (tetraethoxysilane) and its derivatives exhibit well-behaved infrared absoφtion characteristics under near-industrial process conditions (van der Vis et al., J. Mol. Struct. (1992) J. Mol. Struct. 274: 47). Examples disclosed herein incoφorate the use of TEOS in CVD reactions.

Reactions were performed in a chamber configured for substrates of up to 125 mm in diameter. The chamber operates both at high vacuum and at sub-atmospheric pressure. A combination of mechanical and turbomolecular pumps were used, which normally achieve base pressures between lxlO^'7 and lxlO^"6 ton. High vacuum was required between runs to remove residual moisture due to reaction products and ambient adsoφtion on the substrates. For pressure control at subatmospheric conditions, a combination of an in-line throttle valve and pumping speed reductions by the addition of nitrogen at the mechanical pump were used.

Gases were added to the reaction chamber through a water-cooled showerhead. Temperatures of the showerhead did not exceed 150 °C during the process.

Calibration tests indicated no reaction between TEOS and ozone at this temperature (as determined by substrate oxide measurements and by spectra of the gas mixtures). The distance from the showerhead to the substrate was approximately 3 cm. Substrates were heated using tungsten-halogen lamps. Temperatures were measured using J-type thermocouples in direct physical contact with the substrate and were controlled by a Euro therm 2216 controller. Typical process conditions under which the in situ spectra were obtained were: Temperature = 300° C, Pressure = 500 Ton, N₂ flow to TEOS bubbler = 600 seem, N₂ diluent flow = 3 slm, 0₃ in oxygen concentration = 8 %, Total0 flow = 2 slm.

Figures 12 and 13 illustrate mid-infrared beam collection using an ellipsoidal cavity (10). By modifying a conventional FT-IR spectrometer, through substituting an ellipsoidal cavity (10) for the conventional parabolic mirror, the transmission of energy can be increased by about 3-fold, thus resulting in increased optical power of the infrared output beam emerging from the interferometer (40). The use of a circular SiC infrared source enhances the collection of the infrared optical power even further as compared to the use of the conventional glowbar source within the cavity as shown in Figure 13.

Figure 14 illustrates the mid-infrared transmission spectrum by one of the fiber bundles (60) of the present invention (Figure 14b), as compared with the mid- infrared spectrum transmitted using a chalcogenide optical fiber (Figure 14a). The features labeled "Experimental Artifacts" in Figure 14b are due to ambient air in the particular measurement shown and are not inherent to the transmission spectrum of the fiber bundle disclosed in the invention. The intensity of radiation transmitted in the region of from 500 to about 1500 cm^{" 1} is particularly enhanced using the fiber bundle described herein The intensity of the entire mid-mfrared spectrum is also improved using this fiber bundle as compared with chalcogenide fiber As shown in Figure 12, the use of SiC and an elliptical cavity for collection of radiation from the source can further increase the intensity of the infrared spectrum over the use of a glowbar in combination with a conventional FT-IR mirror for beam collection

Figure 15 illustrates the benefit of using the fiber bundle (60) when configured as shown in Figure 3a to transmit an infrared output beam (50) from an interferometer (40) to a gas sample to be analysed A 1 meter length of the fiber bundle shown in Figure 5c with cross section as shown m Figure 3a was used to obtain the in situ spectrum of TEOS shown in Figure 15b For comparative puφoses, the spectrum of TEOS under similar process conditions, but obtained with the infrared spectrometer mounted directly on the CVD chamber (I e with no fiber bundle in the optical path) is shown in Figure 15a This figure illustrates that the TEOS spectrum does not change by being transmitted through the fiber bundle of the present invention

Figure 16 illustrates FT-IR spectra of the starting materials and of the TEOS/ozone process for the CVD of silicon dioxide thm films All spectra were determined in situ under typical or near-typical production process conditions, as described above FT-IR spect m of TEOS in the gas phase of a CVD reactor at 300° C was obtained (Figure 16a) In figure 16b, the FT-IR spectrum of ozone in a CVD reactor at 300° C was determined Figure 16 (c) the gas phase FT-IR spectrum of the TEOS/ozone process The data illustrates the importance of optimizing the intensity of spectral data, particularly in the range of from 500-1500 cm^"

Figure 17 (a) illustrates the conelation of 794 cm^{" 1} absoφtion in the infrared spectrum of TEOS with the partial pressure of its vapour in a CVD chamber Figure 17(b) illustrates the direct measurement of the partial pressure of TEOS in the presence of diluent gases withm the CVD chamber obtained using the peak area determined from the in situ infrared spectrum Pressure may be iteratively adjusted based on spectral data obtained using the system of the invention to achieve real-time adjustment of conditions withm a CVD chamber

Figure 18 illustrates the conelation between the rate of silicon dioxide thin film deposition in TEOS/ozone CVD reactions with the integrated area of an infrared absoφtion peak in the FT-IR spectrum of the gas phase of the TEOS/ozone CVD process Such simple, linear conelations between features in the gas phase FT-IR spectrum of the CVD process with fundamental process parameters such as deposition rate can be used for real-time control of the process based on the FT-IR sensor data

Figure 19 illustrates the conelation of chemical composition of silicon dioxide thin films deposited in a TEOS/ozone CVD reaction with the integrated area of an infrared absoφtion peak in the FT-IR spectrum of the gas phase of the TEOS/ozone CVD process Such simple, linear conelations between features in the gas phase FT- IR spectrum of the CVD process with fundamental thin film properties such as film stoichiometry can be used for real-time control of the product properties of the CVD process

Real-time closed-loop control of infrared spectroscopic peak intensities m a CVD reaction is illustrated in Figure 20 The data was obtained using model-based control of an actual TEOS/ozone CVD process The process response under control directly conelates with silicon dioxide thin film deposition rate, as illustrated m Figure 18 Figure 20 demonstrates control of the deposition rate in the process from infrared spectral data determined for the gas phase of the process

Thus, the present invention applies to control of semiconductor device processing, by effectively achieving data which can be used for real-time feed-back iterative control of processing parameters

All publications cited herein are incoφorated by reference Vaπous modifications may be made without departing from the invention It is understood that the invention has been disclosed herein in connection with certain examples and embodiments. However, such changes, modifications or equivalents as can be used by those skilled in the art are intended to be included Accordingly, the disclosure is to be construed as exemplary, rather than limiting, and such changes withm the principles of the invention as are obvious to one skilled m the art are intended to be included within the scope of the claims

Claims

THE EMBODIMENTS OF THE LNNENTION IN WHICH AN EXCLUSIVE PROPERTY OF PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS

An apparatus for the production and transmission of infrared radiation comprising

1) a mirrored ellipsoidal cavity surrounding an infrared radiation source, located at the focal point of said mirrored ellipsoidal cavity, and said mirrored ellipsoidal cavity producing a collected infrared beam from said infrared radiation source, n) a first optical element tor directing said collected infrared beam to an interferometer, in) said interferometer for receiving said collected infrared beam from said first optical element and producing an output beam,

IV) a second optical element for directing said output beam from said interferometer to a fiber bundle and, v) said fiber bundle for transmitting said output beam,

The apparatus according to claim 1 , wherein said infrared radiation source is selected from the group consisting of a glowbar, a silicon carbide element and an IR laser diode

The apparatus according to claim 1 , wherein said first optical element is selected from the group consisting of one or more mirrors, a beam splitter, a lens, a fiber, a fiber bundle or a combination thereof, and said second optical element is selected from the group consisting of one or more mirrors, a beam splitter, a lens, a fiber, a fiber bundle or a combination thereof

The apparatus according to claim 3 , wherein said first optical element or said second optical element comprises a parabolic mirror 03 - The apparams according to claim 3 , wherein the first optical element comprises a parabolic mirror in combination with a second fiber bundle

The apparams according to claim 1 , wherein said fiber bundle comprises one or more silver halide fibers and a plurality of symmetrically arranged heavy metal fluoride glass fibers

The apparams according to claim 5, wherein said first fiber bundle or said second fiber bundle comprises one or more silver halide fibers and a plurality of symmetrically arranged heavy metal fluoride glass fibers

The apparams according to claim 7, wherein said first fiber bundle or said second fiber bundle additionally comprises silica fibers

A method for transmitting radiation comprising the steps of collecting infrared radiation from an infrared source within a mirrored ellipsoidal cavity to produce collected infrared radiation, directing said collected infrared radiation to an interferometer, producing an infrared output beam from said interferometer, and transmitting said output beam through a fiber bundle

A system for infrared analysis of a medium comprising the system according to claim 1 additionally comprising, l) a beam directing means in optical communication with said fiber bundle, for directing said output beam through said medium and, n) a detector in optical communication with said beam directing means, said detector monitoring said output beam directed though said medium

The system of claim 10, wherein the medium comprises a liquid or a gas

The system of claim 11 wherein the medium comprises a plasma A system for infrared analysis of a solid substrate compnsmg the system according to claim 1 additionally comprising. l) a beam directing means in optical communication with said fibre bundle, for directing said output beam at said solid substrate to produce a reflected and transmitted beam and, a) a detector in optical communication with said beam directing means. said detector monitoring said reflected and transmitted beam from said solid substrate, and determining a property of said substrate

The system of claim 13 wherein the solid substrate is a semiconductor body

A system for infrared analysis of a liquid medium comprising the system according to claim 1 additionally comprising,

I) an unsheathed fibre bundle in optical communication with said fibre bundle, said unsheathed fibre bundle immersed withm said liquid medium, and n) a detector in optical communication with said unsheathed fibre bundle, said detector monitoring said output beam directed though said unsheathed fibre bundle

The system of claim 10 additionally comprising,

I) a fiber bundle connector and n) a radiation transferring element wherein, said fiber bundle connector connects an end of said fiber bundle to said radiation transferring element

The system of claim 16, wherein the radiation transferring element is selected from the group consisting of a housing of an optical element, a CND chamber, an input transfer element, an output transfer element, a detector and a SMA adaptor

18. The system of claim 10, wherein said fiber bundle comprises one or more silver halide fibers and a plurality of heavy metal fluoride glass fibers.

19. The system of claim 11 , wherein said gas is associated with a semiconductor device processing chamber.

20. The system of claim 19, wherein said gas is gas entering a semiconductor device processing chamber.

21. The system of claim 19, wherein said gas is contained within a semiconductor device processing chamber.

22. The system of claim 19, wherein said gas is an exhaust gas stream emanating from a semiconductor device processing chamber.

23. The system of claim 19, additionally comprising feedback control means for adjusting a processing parameter within said semiconductor device processing chamber on the basis of a value obtained by said detector.

24. The system of claim 23, wherein said processing parameter within said processing chamber is selected from the group consisting of temperature, pressure, and flow rate of reactant gas into said chamber.

25. A method for infrared analysis of a medium comprising the steps of: collecting infrared radiation from an infrared radiation source within a mirrored ellipsoid cavity; directing collected infrared radiation to an interferometer; producing an infrared output beam from said interferometer; transmitting said output beam through a fiber bundle to said fluid; directmg said output beam through said fluid to a detector to measure infrared radiation directed through said fluid.

26 A fiber bundle comprising at least one silver halide fiber and a plurality of heavy metal fluoride glass fibers arranged symmetrically within a bundle sheath.

27 The fiber bundle of claim 26, additionally comprising one or more silica fibers

28. The fiber bundle of claim 26, wherein said heavy metal fluoride glass fibers comprise zirconium fluoride fibers.

29. The fiber bundle of claim 26, wherein said silver halide fibers comprise AgBrCl.

30. The fiber bundle of claim 26, being essentially adhesive-free.

31. The fiber bundle of claim 26, additionally comprising a bundle sheath.

32. A fiber bundle connector comprising: i) a male housing comprising a first end and a second end, a bore extending from said first end to said second end capable of receiving a first fiber bundle, said first end having radially compressible fingers for frictionally engaging said first fiber bundle received within said bore, said second end being optionally attachable to a bundle sheath and;

ii) a female housing comprising a first end and a second end, a bore extending from said first end, a receiving cavity disposed at said first end being adapted to receive and radially compress said compressible finger of said male housing and; a means for fastening said first end of said male housing to said first end of said female housing so that when said male housing and said female housing are fastened, said compressible fingers are radially compressed by said receiving cavity

The connector of claim 32, wherein said means for fastening comprises screw threads located on an outer surface of said male housing, being adapted to threadedly engage screw threads located on an inner surface of said female housing

The connector of claim 32 wherein said means for fastening comprises a snap- fit fastening means

The connector of claim 32, wherein at least said male housing is formed of a material which is non-reactive with silver halide

The connector of claim 35, wherein said material which is non-reactive with silver halide is selected from the group consisting of titanium and gold

The connector of claim 32, wherein said female housing is connected to a radiation transferring element

The connector of claim 37, wherein said radiation transferring element is selected from the group comprising an optical element housing, a CVD chamber, an input transfer element, an output transfer element, a detector and a SMA adaptor