FR2609347A1 - SUPERFICIAL ACOUSTIC WAVE DEVICE AND METHOD FOR ITS ADJUSTMENT - Google Patents

Abstract

THE INVENTION RELATES TO A SURFACE ACOUSTIC WAVES DEVICE AND A PROCESS FOR ADJUSTING ITS CHARACTERISTICS. THE DEVICE INCLUDES A BASE 12 AND A COVER 14, ONE OF WHICH IS TRANSPARENT TO ELECTROMAGNETIC ENERGY 30. MATERIAL 26 IS DEPOSITED ON AN INTERIOR SURFACE OF THE BASE OR COVER AND IT IS ELIMINATED BY THE ELECTROMAGNETIC ENERGY IN ORDER. DEPOSIT ON SURFACE 12A OF SURFACE WAVE PROPAGATION IN ORDER TO MODIFY PROPAGATION SPEED CHARACTERISTICS. THE INVENTION APPLIES IN PARTICULAR TO SURFACE ACOUSTIC WAVE RESONATORS.

Description

-1

  The present invention relates generally to

  to superficial acoustic wave devices

  and more particularly the adjustment of the characteristics

  frequency characteristics of an acoustic wave device

superficial issues.

  As is known in the art,

  Surface acoustic wave positives such as resonators, delay lines, filters, and pressure transducers are used in a variety of applications. In general, a surface acoustic wave device comprises at least one

  transducer comprising a set of conductive parts

  those who is willing on or withdrawing to the party of

  upper surface of a piezoelectric substrate.

  A new type of case has been developed which

  hermetically encloses the substrate of the device

  superficial acoustics. This new housing

  carries two piezoelectric substrates which are sealed together by glass sintering, as described in an article entitled "Saw Resonator Fried Bonded Pressure Transducer" by D. Weirauch et al, Proceedings of the IEEE Ultrasonic Symposium, 1979, page 874 and in an article entitled "Long Term Aging, A Mechanical Stability of 1.4 GHz SAW Oscillators" by M. Gilden et al, Proceedings of the IEEE Ultrasonic Symposium, 1980, page 184; a second type of housing is described in U.S. Patent No. 4,270,107 to Parker et al., issued May 26, 1981, entitled "Stabilized

  Surface Wave Device "and assigned to the plaintiff.

  Although these cases bring a condition-

  improvement and the possibilities of handling

  superficial acoustic wave devices, a

  The problem with them is that during the manufacturing process

  cation of the housing, the frequency characteristics of the superficial acoustic wave device under -2-

  box are changed in relation to those of a

  before putting it in a box. For example, for

  superficial acoustic wave resonators function

  around 350 MHz, this difference in frequency

  quence can be on average about 45 ppm and can

  have a standard deviation as high as + 15 ppm.

  For other types of devices that are designed to operate at higher frequencies, the amplitude and standard deviation of this offset increase, so that fine tuning of the frequency characteristics of the surface acoustic wave device is more difficult. In many applications, a possibility of fine tuning the frequency of + 1

ppm would be desirable.

  One solution to this problem is to use external electrical components to adjust the frequency characteristics of the circuits using the surface acoustic wave device. The

  The problem with this solution is that this type of

  Frequency frequency setting is time consuming, is relatively expensive because the number of components

  necessary for a particular application it

  positive surface acoustic wave is increased

  and furthermore, the components themselves can contribute

  to fluctuate frequency in circuits

  which include devices of this kind.

  The invention therefore relates to a method of change-

  of the velocity characteristic of a superwave wave.

  on a surface that supports propagation

  of superficial waves, consisting of directing energy

  through a first of a base and a lid,

  enclosing said surface towards a first material

  placed on said surface to form a layer of a second material on said surface to modify the velocity characteristic of that surface. With this particular arrangement, the second material layer on the base produces a small localized variation in the velocity characteristic of a surface wave of the surface that supports the propagation of this surface wave, thereby allowing the adjustment of the characteristics of the surface wave. Frequency characteristics of acoustic wave devices

superficial in a case.

  In another aspect, the invention relates to a

  method of changing the speed of a superficial wave

  of a surface acoustic wave device-

  the sub-casing of directing energy inci-

  through a cover of the boxed device to remove a portion of a layer of material disposed on a surface wave propagation surface of the surface acoustic wave device. With this particular arrangement, the discarded material produces a small localized variation of the properties

  acoustics of the super-wave propagation surface

  to provide a concomitant variation in the frequency characteristics of the wave

superficial acoustics.

  In yet another aspect, the invention

  A method of modifying the speed of a surface wave of a surface acoustic wave device in a package comprising:

  lid on the superficial wave device,

  an enclosure on this surface wave device-

  with at least one of the lid and base

  staggered by a material that is virtually transparent

  to energy in a wavelength selective range.

  A layer of material is arranged on a part of

  inner surface of the lid. Energy is direc-

  to this layer of material through the lid

  or the transparent base to eliminate specific parts

  of the material of the diaper, and these parts de-

  They are removed and deposited again on the surface of propagation of a surface wave. With this particular arrangement, the velocity characteristic of a surface wave and therefore, the frequency characteristics of a surface acoustic wave device under a case can be adjusted after the case of the wave device

  superficial acoustics. The matter that has become new

  calf filed produces a small localized modification

  acoustic properties of the piezoelectric surface

  that, thus changing the speed of the superficial waves

  in propagation. As a result, this change in surface wave velocity produces a variation

  associated frequency characteristics of the

  tif with superficial acoustic waves.

  According to yet another aspect of the invention, the lid portion of the material is made of quartz and

  this quartz is transparent to the luminous energy

  from a laser having a wavelength in the

  from about 0.185 micrometers to 4 micrometers. On the inner part of the quartz cover is arranged

  a buffer consisting of a first layer of a

  thermally buffering a second layer of energy conversion material and a third

  layer of a material that can be removed or evaporated.

  The incident optical energy is directed to this buffer.

  The quartz cover and the first layer constitute

  killing the thermal buffer material are substantially transparent to the incident optical energy. But this incident energy heats up the intermediate layer of energy conversion between the buffer layer

  thermal and the layer that can be removed. The chain

  their developed in the energy conversion layer

  causes the layer to be eliminated or evapo-

  is eliminated or evaporates and settles again on -

  underlying parts of the piezoelectric surface

  than. The first dielectric layer is provided to buffer the quartz cover with respect to

  the heat associated with the conversion layer of

  energy. With this particular provision, the characteristics

  frequency characteristics of an acoustic wave device

  surface ticks can be adjusted using

  a laser that selectively redeposit a pre-selected part of

  determined the layer that can be eliminated or

  pored on the superficial wave propagation surface-

  of the surface acoustic wave device, thereby adjusting the velocity characteristic of a surface wave and therefore the characteristics

  in frequency of the acoustic acoustic wave device

cial.

  In yet another aspect, the invention

  identifies a method of modifying the velocity characteristic of a surface wave of a device

  superficial acoustic waves in a casing,

  both to have a cover made of a material that is transparent to electromagnetic energy,

  within a specified wavelength range, the

  vercle being disposed to enclose a surface wave propagation surface. A highly convergent beam or a pair of beams, each at an angle of incidence determined to converge on said surface, is directed thereto to produce a beam of sufficient intensity to

  selectively remove parts of the surface of

  pagation. With this particular provision, in

  selectively removing parts of the surface of

  piezoelectric paging, a small modification

  acoustic properties and, consequently,

  of the velocity characteristic of a superficial wave

  is produced. The frequency characteristics of the superficial acoustic wave device are

therefore also modified.

  Other features and benefits of

  the invention will appear during the description

who will follow.

  In the attached drawings given only at

  examples of non-limiting examples:

  FIG. 1 is a plan view of a resonator

  FIG. 2 is a sectional view along the line 22 of FIG. 1, FIG. 2A is an enlarged view along the line 2-2 of FIG. figure 2,

  FIG. 3 is a plan view of a resonator

  FIG. 4 is a sectional view of FIG. 4, a section on line 44 of FIG. 3; FIG. 4A is an enlarged view of part of FIG. along line 4A-4A of FIG. 4, FIG. 5 is a sectional view of another embodiment of the invention using convergent pairs of directed energy beams, FIG. 5A is an enlarged view. along the line 5A-5A of Figure 5, Figure 6 is a section of another embodiment of the invention using pairs

  convergence of energy bundles directed to eliminate

  A pad is deposited on a surface wave propagation surface, FIG. 6A is an enlarged view along the line 6A-6A of FIG. 6, FIG. 7 is a sectional view of another embodiment. wherein a gaseous mixture is enclosed in the housing, with incident energy directed to the mixture to produce a layer of material on the surface wave propagation surface, and

  Figure 7A is a larger scale view.

  following line 7A-7A of Figure 7.

  As shown in FIGS. 1, 2 and 2A, a superficial acoustic wave device under

  housing, in this case a resonator 10, comprising

  base 12 with a surface 12a which supports surface wave propagation, a cover 14 and

  a seal 16 in glass sintering. The base 12 is

  in this case a quartz of cut ST or of

  eg ST rotated, with, arranged on its surface 12a, two nested transducers 20 and 24 (IDT) and reflector gratings 27, 29. The nested transducers 20 and 24 are coupled with bus bars 18a and 18b, and 19a and 19b respectively . On the base 12 is disposed the cover 14, also made of a quartz of

  ST cut or ST cut tour. Quartz is generally

  85% to 95% transparency to energy having wavelengths in the range of about

  0.185 micrometers at 4.0 micrometers for samples

  lons with a thickness of 1 to 3 mm. Alternatively, the base

  12 and the cover 14 may be constituted by

  very transparent materials, such as lithium niobate.

  The base 12 and the lid 14 are sealed together in

  using a suitable seal 16 in glass sintering.

  The lid 14 has a width wc lower than the width

  wb of base 14, so that when the cover

  key is sealed on the base, the bus bars 18a and

  18b, and 19a and 19b are exposed on the peripheral

  -8- of the base, to establish electrical contacts

with external coposants.

  As shown more particularly in FIG. 2A, the inner surface 14a of the cover 14 bears on one of its parts, a layer preferably made of a composite layer 26 constituted by a layer 26a of thermal buffer or shock absorption, a 26b layer of thermal absorption or energy conversion

  and a layer 26c of evaporation or thermal elimination

  nomic. In this preferred arrangement, the thermal shock absorption layer 26a consists of a material

  dielectric which is virtually transparent to the

  incident energy which is directed through the cover 14 of the surface acoustic wave device in a manner to be described later, but which

  has sufficient thermal resistance to ensure

  obtain a thermal buffer from the lid 14 with respect to

  the heat developed in the heat absorption layer

  26b, as will be described. The conversion layer

  energy supply 26b is made of a material that absorbs the incident energy directed through the cover 14 and the thermal shock layer 26a and converts

  this incident energy directed into radiation energy-

  or in heat. The elimination or evaporation layer

  thermal poration 26c is arranged above the neck.

  26b and it absorbs a portion of the radiation energy developed in the layer 26b and, if this energy has a sufficient intensity, the

  26c film is selectively removed, in particular

  bond removed or evaporated from the lid to deposit or condense on the surface 12a, as shown in Figure 4. The quantity of this deposited mass is chosen

  to sufficiently modify the characteristic of

  superficial waves of the acoustic wave device

  superficial ticks and therefore to modify g9-

  the frequency characteristics of the on-line device

  surface acoustics, as needed.

  As shown in Figures 3, 4 and 4A, the

  The incident energy 30 is directed through the cover 14 to the control pad 26. The incident energy passes through the transparent buffer layer 26a and is absorbed by specific underlying portions of the energy conversion layer 26b. Layer 26b converts the directed energy into heat. The heat in layer 26b leads to removal or evaporation

  of parts of the layer 26c. Depending on the duration of the

  the power level, the wavelength and the repetition frequency of this energy, the

  26c is evaporated at low energy levels or eliminated

  mined at higher energy levels. In addition,

  at sufficiently high levels, decisive parts

  from each of layers 26a-26c may be eli-

  mined. The material removed, either by ablation or by evaporation, condenses and is deposited as a layer 34 on the base portion 12 of the surface acoustic wave device 10. The presence of the layer 34 on the surface 12a of the base 12 reduces the speed of surface waves in this region due to mass load effects, when the surface wave propagates. By increasing the number of

  these layers 34 and their width as well as the total mass

  the, the adjustment range of the speed characteristic

  superficial wave is increased.

  Specific examples of manufacturing devices

  according to the invention will now be described. com-

  as shown in FIGS. 3, 4 and 4A, incident energy, in the present case in the form of light beams, originating from laser sources as indicated by FIG.

  the painting, are formed with lengths that

  almost the length of the surface of

  -1O- pagation of acoustic waves and with widths that are generally of the order of the wavelength of the surface acoustic wave device (this is

  to say in the range of 2.5 micrometers to 50 micrometers

  very). In other words, a long narrow line follows

  the length of the acoustic propagation surface

  that, centered and parallel to the acoustic opening of the nested transducer elements, is directed towards the

  quartz cover. This energy reverses the

  quartz key 14 and is absorbed by the composite adjustment pad disposed on the inner surface

  14a of the lid 14. With this configuration of

  laser beam, the 26b aluminum layer is heated

  selectively in regions receiving the

  incident laser beam. In response to this local heating

  of the aluminum layer, parts 26c are

  porees or removed from the diaper and deposited on

  the underlying surface 12a of wave propagation su-

  perficielles. In particular, given that the

  their frequency adjustment is related to the mass of the material deposited on the surface wave propagation surface, the frequency setting value per line of the laser can be controlled by the width and

  the energy density of the beam as well as the quantity

  material deposited on the inner part of the

  14. It seems that the maximum value of the

  Frequency placement can exceed 10,000 parts per million if the total area between the nested transducers is used. But it appears

  also that displacements of this order are degrading-

  the insertion losses and the empty Q factor of the device. But since about 25 to 50 parts per million are usually enough to hold

  account of the frequency uncertainty after the

  the case, only a small part of the

  buffer surface is usually deposited on the surface

active face between the IDTs.

  Four devices operating at 402 MHz

  were granted according to the technique described above.

  A film with three levels, as shown on

  FIG. 4, consisting of a layer of aluminum oxide

  nium Al203 with a thickness of 400K corresponding to the layer 26a, a layer of aluminum with a thickness of 100 oA corresponding to the layer 26b and a layer

  aluminum oxide with a thickness of 250K correspon-

  layer 26c was deposited on the part

  lid thickness 14. The thicknesses of the layers

  12a to 12c can be chosen to bring

  different mass loading values by pulse

  incident light. Therefore, the layer 26a may have a thickness generally in the range of 200 to 1000X, the layer 26b may have a thickness in the range of 25 to 200K and the layer 26c

  can have a thickness in the range of 50 to 500X.

  The power level, the number of

  and the number of deposited lines provided for the four examples of the invention as well as the initial frequency, the final frequency and the displacement of

  frequency of these devices appear in the table.

bleau, examples 1 to 4.

  Alternatively, the incident laser beam can be directed through the base 12 to the adjustment buffer 26. The incident laser energy can then be

  used to remove regions from the buffer

  on the lid, for example by turning over the

  surface acoustic wave, to change

  again mass loading in this region

  and therefore, the speed characteristic of on-

  superficial of the surface acoustic wave device.

BOARD

  LASER TECHNICAL DEVICE LONGWEJR DENSITY DURATION FREQUENCY WIDTH NUMBER OF LINES fo ADJUSTMENT A f I.D. ADJUSTMENT OF ENERGY WAVE OF LINE IMPL- FREQUENCY f

BY SION

IMPULSE

  } v J / cmn2 ns hz Pm MHz MHz PPM 1. FILM Excimer 0,193 5 15 1 7 5 401,831 401,817 -35 3 levels on cover

2. 5 15 1 7 5 401,840 401,828 -30

  3. Nd: YAG 1.06 0.0025 250 1024 50 5 402.178 402.166 - 30 4. Nd: YAG 1.06 0.00325 250 1024 60 1 402.219 402.203 -40 5. ELIMINATION cEbimnr 0.193 7 15 50 50 0.1 402.174 402.170 -10

OF SURFACE

DEVICE IUD

  6. C (1IVCSIMQ Exciner 0,193 5 15 10 100 5 401,962 401,955 -17

CHEMICAL

of AL-O Cerme t Qo Cl -13-

  Figure 5 represents another embodiment of

* sation of the invention for selectively modifying the frequency characteristics of a device underperformed acoustic wave device. In this case, the superficial acoustic wave device

  box 10 'comprises the abovementioned base 12 and a cover

  cle 14, as has been described generally in re-

  Figures 1 and 2. According to this aspect of the invention,

  directed energy, in the form of the light energy of an excimer laser is directed through the quartz cover 14 to the base 12. In this case, two excimer laser light beams are directed to

  through the quartz cover 14 at an angle of

  determined to converge on the basis of quartz 12 and selectively remove a portion of

  this base 12 in one of its regions, placed

  be the two nested transducers as shown

  particularly Figure 5A. As a variant, three

  or more, or a highly convergent beam may be suitable. The power density at the point where the beam (s) converge must be sufficient to eliminate specific quantities of material. Since the quartz cover with a thickness of 1 to 2 mm generally transmits light at about 85% -95%, the power density at the point of convergence must be sufficient to eliminate the

  quartz in this region. With this particular arrangement

  because the acoustic properties

  of the superficial wave propagation surface

  the two transducers 20 and 24 are modified by

  selective material removal, the characteristics

  of superficial wave velocity between the two

  transducers are also modified. Thus, the frequency

  the device with this provision is amended

  selectively. Also, the number, width, and depth of these regions disposed in the superficial wave propagation surface portion

  base 12 can be chosen to ensure

  determined placement of acoustic frequency, and by

  of the frequency characteristic of the surface acoustic wave device. In general, the depth of the grooves is about 0.5 micrometer and their width is of the order of the wavelength of

  propagation of the superficial wave (2 to 50 micrometers).

  With this particular arrangement, the intensity of the beams 30a and 30b directed through the quartz cover 14 is insufficient to break or disturb the material of the cover. But since, at the point of convergence of the two beams, the intensity of the latter is added, the intensity of the beam is then sufficient to eliminate a determined part 12c of the surface of propagation of superficial waves.

  12a. Since the mass and the propagation path

  tion of the surface wave propagation surface-

  are modified by this provision, the speed of propagation of superficial waves and consequently

  the frequency of the device are also changed.

  Example 5 in the table shows the results of a

  set using this technique.

  FIG. 6 represents yet another embodiment of the invention which comprises a buffer of

  setting 26 disposed on the base in the acoustic opening

  as nested transducers. In this case, a

  Preferably, two or more convergent laser beams may be suitable for selectively irradiating a portion of the adjusting buffer 26 and for modifying the molecular bonds of that portion of the buffer. There too, given that the mass load in the region o

  the composition of the material is changed, the properties

  acoustic characteristics and, consequently, the superficial velocity

-15-

  the frequency characteristics of the device

tif are also modified.

  Several solutions may be suitable for changing

  the molecular links of the control buffer material. For example, an aluminum-oxygen cermet as described in conjunction with an article entitled "Submicron Patterning by Projecting Excimer-Laser-Beam"

  Induced Chemistry "by Ehrlich et al., J.Vac., Sci., Tech.

  B 3 (1) Jan / Feb I985 can be used. In that case,

  a layer of cermet is deposited on the buffer of

  26. The excimer energy is directed to the control buffer and in response the Al-O bonds are broken and localized growth of A1203 in the buffer of

  setting occurs. Also, the spacing and the

  Some of the localized growth regions of A1203 are chosen based on the desired value of surface wave velocity changes. An example of this adjustment technique is represented by Example 6

In the picture.

  Alternatively, Al 2 O 3, Al layers may be provided as control buffer 26 and the latter is also subjected to excimer light selective regions and the Al-Al and Al-O bonds are broken and a new phase is introduced. Al20x is formed, ox

  represents a non-stoichiometric composition.

  Another technique consists in depositing a

  The cavity of the housing 10 is filled with a gas reacting O2 or NO3, for example, under a pressure generally in the surface.

  2 X 10-6 torr at 1 X 10 -4 torr. Incidental energy

  is also directed to the adjustment buffer 26

  o Al-Al links are broken, resulting in

  pyrolytic release of A1203. By controlling the value of the irradiated area, the desired value of the variation

  superficial wave velocity is obtained.

  Figures 7, 7A show another embodiment of the invention. In this case, the superficial acoustic wave device

  housing constituted by the cover 14 and the basel2 con-

  holds reactive gases 32 hermetically sealed.

  A laser beam, such as excimer light, Nd-YAG, etc., is directed through the device to photolytically break the bonds of these reactants and to deposit from this photolytic reaction

  a material on the super-wave propagation surface

  ficial. In this case, certain configurations

  of excimer light are provided to deposit

  definite figurations of matter on the surface.

  The reacting gases may comprise oxygen and a

  source of a suitable metal such as aluminum, silicon

  cium, etc. For example, TMAl (trimethylaluminum),

  SiH4 silam, etc. may be suitable. Particulate gas

  bind chosen for the metal source for example must be stable during the hermetic sealing operation

  glass sintering in the types of housing used

this seal.

  The excimer laser light can be directed to these determined gases and photolytically break the bonds of the metal source gas. The free metal then reacts with oxygen and a metal oxide layer 34 'is deposited from the vapor on the substrate. Thus, a localized region of A1203 can also be grown on the surface wave propagation surface.

  After describing preferred modes of

  of the invention, it now appears to the

  art that other embodiments incorporate

  his concepts can be used. Furthermore, it

  It also appears that a beam or a pair of

  Convergent cages may be suitable for selective

  Alternatively, a buffer disposed between the two nested transducers on the base 12, as shown in FIG. 6, or to remove or re-deposit portions of a control pad disposed on the inner portion of the cover 12, for example by directing the bundles through the base 12 or the lid 14. It thus appears that the embodiments are not limited to those described but are only by the

  framework and the spirit of the appended claims.

2-609347

-18-

Claims (54)

  A method of adjusting the characteristics of a surface acoustic wave device, characterized in that it consists essentially of directing energy (30) to a material (26) disposed on a propagation surface (12a). of superficial waves of a device (10O) with superficial acoustic waves   casing, through a first of a part of a cover   key (14) and a base portion (12) of the device   superficial acoustic waves in a housing, to de-   placing a second material (34) on said surface wave propagation surface in order to change the   acoustic properties of said surface.   2. Process according to claim 1, characterized   in that said first material (26) is disposed on a first one of an inner surface of the lid (14) or the base (12).   3.Procédé according to claim 2, characterized in that said first material (26) is disposed on the cover and the incident energy (30) is directed on said first material to remove a selected portion to form said second material (34). ) on said surface.   4. Process according to claim 2, characterized   characterized in that said first material (26) is disposed on an inner surface of said base (12), said inner surface (12a) being the supporting surface   a superficial wave propagation and said energy   directed geometry being selected to eliminate a   selected portion of said first material of said   surface for forming said second material (34) on the said surface.   The method of claim 1, characterized in that said first material is said surface wave propagating surface (12a) and said   energy (30) is directed to said surface to eliminate   a selected portion of said surface and forming said second material. 6. Method according to claim 1, characterized in that said first material (26) is disposed on said surface (12a) and the energy (30) is directed towards   said first material for changing the chemical bonds   of said first material and convert it to said second material (34).   7. Process according to claim 6, characterized   in that said first material comprises a   che (26c) of material disposed on said surface and a reacting gas disposed above said surface,   the energy (30) being directed to said first material   re for incorporating said reactant gas into said   layer of material and thereby form said second material re.   8. Process according to claim 1, characterized   in that said first material consists of reactant gases (32) enclosed between said base (12) and said cover (14), said energy (30) being directed   to said reacting gases to break photolytically   the connections of the said gases and thus produce the   material from said reactant gases.   9. Process according to claim 8, characterized   in that said reactant gases contain   oxygen and a gas with a metal ion.   10. Method of setting characteristics   of a device with superficial acoustic waves,   characterized in that it consists essentially of   forming a base (12) with a surface (12a) which supports surface wave propagation, disposing a first material (26) on said surface wave propagation surface, having a cover (14)   on said surface wave propagation surface   them and said first material and to direct a   laser energy beam (30) through a first one of said lid and said base to a selected portion of said first material to form a second   material (34) on said base and thereby change the   Acoustic properties of the propagation surface of superficial.   11. The method of claim 10, wherein   characterized in that said first material is disposed on a first interior surface of the lid or from the base.   12. The method of claim 11, characterized   in that said first material (26) is   on the cover and the laser energy (30) is directly   to said first material to remove one   selected part and thereby form said second ma- (34) on said surface.   13. The method of claim 11, wherein   characterized in that said first material (26) is   placed on an inner surface of said base, said inner surface being the supporting surface (12a)   a superficial wave propagation and said energy   the laser is selected to eliminate some   selected from said first material of said   face to form said second material (34) on surface.   14. The method of claim 10, wherein   characterized in that said first material is said   surface of propagation of superficial waves and la-   said laser energy is directed to said surface   to remove a selected part and train the- said second material.   The process according to claim 1, characterized   Wherein said first material is disposed on said surface and said laser energy is directed to said first material to change the chemical bonds of said first material and convert it to said second material.   16. Process according to claim 6, characterized   in that said first material comprises a   layer of material disposed on said surface and a reacting gas (32) disposed above said surface, the laser energy (30) being directed toward said material to incorporate said reactant gas into the   material and thus form said second material.   17. The method of claim 10, wherein   characterized in that said base and said lid are   said surface of propagation of superficial waves   and said material consists of reactants   (32) enclosed between said base and said cover,   said laser energy (30) being directed to said reacting gases to photolytically break the bonds of said gases and to form the second material from said reactant gases.   18. The method of claim 17, wherein   characterized in that said gases (32) contain oxy-   gene and a gas containing aluminum.   19. A method of adjusting the surface wave velocity characteristics of a case-in-situ acoustic wave device, characterized   in that it consists essentially of having a   vercle (14) made of a material that is transparent   in a wavelength range of electromagnetic energy   on a surface (12a) of surface wave propagation, on an inner portion of which is disposed a layer of material (26) and directing energy (30) in said wavelength range to said layer of material, through the cover, to remove a selected portion of said material   of the layer and for said selected eliminating portion   is deposited on the underlying surface of formation of superficial waves.   20. Process according to claim 19, characterized in that the layer (26) disposed on the part   inside of the lid is a composite layer,   carrying: a first layer (26a) consisting of a thermal buffer material disposed on the quartz cover, a second layer (26b) of a material that absorbs   the incident electromagnetic energy and converts   said energy absorbed in radiation energy, said layer being disposed on the thermal buffer layer   and a third layer (26c) disposed on said second   of layer, reacting to the energy released by the thermal conversion layer in selected portions, removed, deposited on the propagation surface superficial waves.   21. The method of claim 20, characterized   in that the first layer (26a) consists of aluminum oxide, the second layer (26b) consists of aluminum and the third layer (26c) consists of aluminum oxide.   22. The method of claim 21, characterized   in that the thickness of the first aluminum oxide layer is in the range of 200 R to 1000, the thickness of the aluminum layer lies in the   range from 25 to 200 R and the thickness of the oxy-   of aluminum is in the range of 50 f to 500 R.   23. The method of claim 19, characterized   in that the energy (30) is supplied in the form pulses of laser light.   24. Process according to claim 23, characterized   in that the laser light is produced by a laser   excimer serum having a wavelength of 193 nanometers. -23-   25. The method of claim 24, characterized   in that several pulses of said excimer laser light are directed to the material layer   disposed on the inner part of the cover to form   sea several deposited regions of matter on the surface   of superficial wave propagation.   26. The method of claim 22, characterized   rised in that the energy is light coming from an excimer laser.   27. The method of claim 26, characterized   characterized in that a plurality of beams of said excimer light are directed to the composite layer (26) to form, in response to said laser light, a plurality of deposited lines of the material removed on the surface   of superficial wave propagation.   28. The method of claim 24, characterized   in that the laser is an Nd: YAG laser.   29. The method of claim 28, characterized   in that several pulses of said Nd: YAG laser light are directed to the material layer   disposed on the inner part of the cover to form   several areas deposited on the surface   this of superficial wave propagation.   30. The method of claim 22, characterized   rised in that the energy is light coming from of an Nd: YAG laser.   31. The method of claim 30, characterized   rised in that several beams of said light   Nd: YAG are directed to the composite layer to form   sea, in response to ladit laser light, several lines   of the material removed on the surface of the paging of superficial waves.   32. Superficial acoustic wave device   characterized in that it comprises a base (12) with a surface (12a) which supports propagation -24-   superficial waves, comprising at least one trans-   driver (20,24) coupled with said propagating surface   surface waves, a cover (14)   on said base, for closing said pro-   pagation of superficial waves, said cover being made of a material which is optically transparent   to electromagnetic energy in the long range   wavelengths from about 0.185 micrometers to 4 micrometers   and a layer of material (26) disposed on said surface spread face.   33. Device according to claim 32, characterized   characterized in that said layer of material is a   composite layer comprising a first layer (26a) of a thermal buffer material, a second layer (26b) of a thermal absorption material and a   third layer (26c) of a material eligible for thermally mined.   Apparatus according to claim 33, characterized   characterized in that said composite layer (26) of   re is disposed on an inner portion of said cover cle (14).   35. Device according to claim 34, characterized   characterized in that a portion of said layer of material is disposed on the wave propagation surface (12a) superficial.   36. Device according to claim 33, characterized   characterized in that said base (12) and said cover (14) are sealed together by glass sintering (16).   37. Device according to claim 35, characterized   in that said base and said cover are   sealed together by glass sintering (16).   38. Device according to claim 37, characterized   in that the cover and said base are   each with ST-cut quartz or ST-25- round cut.   39. Device according to claim 38,   characterized in that said layer of material (26) comprises   a first portion disposed on said lid (14) and a second selected portion disposed on   said surface wave propagation surface (12a) the.   40.Device according to claim 39, characterized   characterized in that said layer of material consists of aluminum.   41. Device according to claim 32, characterized   characterized in that said layer of material has a first portion disposed on said cover (14) and a second selected portion disposed on said   surface (12a) for propagating surface waves.   42. Device according to claim 41, characterized   characterized in that said layer of material consists of aluminum.   43. Device according to claim 32, characterized   characterized in that said layer of material is a first   first layer consisting of a reactive gas (32)   closed by said lid and said base and a layer   of material being disposed on said propellant surface formation of superficial waves.   44. Device according to claim 43, characterized   characterized in that a second material consisting of   reacting gas (32) and a layer of material is   on said superficial wave propagation surface heaven them.   45. Device according to claim 32, characterized   characterized in that the layer of material is a first layer and consists of a pair of reacting gases (32)   enclosed by said lid and the base.   46. Device according to claim 45, characterized   in that a second layer of material is' -26-   product of the reaction of said pair of reactants   placed on said propagation surface of on- superficial.   47. Device according to claim 46,   characterized in that said product is a metal oxide. 48. A method of adjusting the superficial wave velocity characteristic of a surface acoustic wave device, characterized in that it consists essentially of disposing a boVtier comprising a lid part (14) and a part   (12) of which at least one is made of a material   re that is transparent to electromagnetic energy   tick in a selected wavelength range,   said base and said cover being arranged for   close a surface (12a) of super-wave propagation   and directing a pair of beams (30a, 30b) of laser energy to said surface wave propagation surface through a first one of said   base and cover so that said beams converge   on the surficial wave propagation surface-   to selectively eliminate parts of the said surface.   49.A method according to claim 48, characterized   in that said first of the base and the cover   key is made of a quartz cut ST or ST rotated and   said beams of laser energy from a laser excimer   50. Surface acoustic wave device   the, characterized in that it comprises a base (12) with a surface (12a) which supports a propagation   superficial waves, comprising at least one transducer   tor (20,24) coupled with said surface wave propagation surface, said propagation surface   of superficial waves comprising a dwelling in the   Said surface, a cover (14) disposed on said   base for enclosing said propagation surface of on-   superficial and in which at least one of the   said base and said cover is transparent to the energy optics.   51. Device according to claim 50,   characterized in that said housing is a narrow line formed in said surface.   52. Device according to claim 51,   characterized in that said base comprises a pair of said transducers (20,24) and said narrow line is formed across and parallel to a portion   an acoustic opening of said pair of transducers tors.   53. Device according to claim 50,   characterized in that said base is made of a quartz cutting ST or ST rotated.   54. Device according to claim 50,   characterized in that said lid is made of a quartz cutting ST or ST rotated.