U.S. patent application number 11/292195 was filed with the patent office on 2006-05-04 for gas laser device and exposure apparatus using the same.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Yoshiyuki Nagai, Naoto Sano.
Application Number | 20060093009 11/292195 |
Document ID | / |
Family ID | 17497503 |
Filed Date | 2006-05-04 |
United States Patent
Application |
20060093009 |
Kind Code |
A1 |
Sano; Naoto ; et
al. |
May 4, 2006 |
Gas laser device and exposure apparatus using the same
Abstract
A gas laser device includes a laser gas supplying device in a
chamber for supplying a laser gas to an exciting region in the
chamber, and an exciting device for exciting the laser gas supplied
to the exciting region. The gas laser device controls the laser gas
supplying device so that, when the laser gas is excited by the
exciting device, the laser gas is circulated at a first circulating
rate and so that, when the laser gas is not excited by the exciting
device, the laser gas is circulated at a second circulating rate
lower than the first circulating rate.
Inventors: |
Sano; Naoto;
(Utsunomiya-shi, JP) ; Nagai; Yoshiyuki;
(Utsunomiya-shi, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
17497503 |
Appl. No.: |
11/292195 |
Filed: |
December 2, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09163402 |
Sep 30, 1998 |
|
|
|
11292195 |
Dec 2, 2005 |
|
|
|
Current U.S.
Class: |
372/58 ;
372/55 |
Current CPC
Class: |
H01S 3/2251 20130101;
H01S 3/2256 20130101; H01S 3/2258 20130101; H01S 3/036
20130101 |
Class at
Publication: |
372/058 ;
372/055 |
International
Class: |
H01S 3/223 20060101
H01S003/223; H01S 3/22 20060101 H01S003/22 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 3, 1997 |
JP |
9-271253 |
Claims
1-20. (canceled)
21. A gas laser device, comprising: laser gas supplying means in a
chamber for supplying a laser gas to an exciting region in the
chamber; and exciting means for exciting the laser gas supplied to
the exciting region, wherein said gas laser device controls said
laser gas supplying means so that, when the laser gas is excited by
said exciting means, the laser gas is circulated at a first
circulating rate and so that, when the laser gas is not excited by
said exciting means, the laser gas is circulated at a second
circulating rate lower than the first circulating rate.
22. A gas laser device according to claim 21, wherein said laser
gas supplying means includes a blower.
23. A gas laser device according to claim 22, wherein said gas
laser device controls a number of revolutions of said blower.
24. A gas laser device according to claim 21, wherein said exciting
means includes two discharging electrodes disposed to sandwich said
exciting region therebetween.
25. A gas laser device according to claim 24, wherein said exciting
means further includes a resonator.
26. A gas laser device according to claim 25, wherein said
resonator comprises a pair of mirrors.
27. A gas laser device according to claim 26, wherein said pair of
mirrors includes a total reflection mirror.
28. In an exposure apparatus having a main assembly for exposing a
substrate to a laser light from a laser light source, the laser
light source comprising: a gas laser device including (i) laser gas
supplying means in a chamber for supplying a laser gas to an
exciting region in the chamber, and (ii) exciting means in the
exciting region for exciting the laser gas supplied to the exciting
region, wherein said gas laser device controls said laser gas
supplying means so that, when the laser gas is excited by said
exciting means, the laser gas is circulated at a first circulating
rate and so that, when the laser gas is not excited by said
exciting means, the laser gas is circulated at a second circulating
rate lower than the first circulating rate.
29. An apparatus according to claim 28, wherein said laser gas
supplying means includes a blower.
30. An apparatus according to claim 29, wherein said control means
controls a number of revolutions of said blower.
31. An apparatus according to claim 28, wherein said exciting means
includes two discharging electrodes disposed to sandwich said
exciting region therebetween.
32. An apparatus according to claim 31, wherein said exciting means
further includes a resonator.
33. An apparatus according to claim 32, wherein said resonator
comprises a pair of mirrors.
34. An apparatus according to claim 33, wherein said pair of
mirrors includes a total reflection mirror.
35. An exposure apparatus having an exposure job to be executed for
exposure of a plurality of substrates, said apparatus comprising: a
laser light source including (i) a chamber for confining a laser
gas therein, (ii) a discharging electrode for exciting the laser
gas through electrical discharge so that laser light is outputted
from said chamber, and (iii) circulating means for circulating the
laser gas inside said chamber so that the laser gas passed through
an electrical discharging region of said discharging electrode is
circulated within said chamber and returns back to the electrical
discharging region of said discharging electrode; an exposure
apparatus major assembly arranged to perform exposure by use of
laser light from said laser light source; and control means for
controlling said circulating means, wherein said exposure apparatus
operates, after said laser light source is put into a warming-up
state, into a sequence of a start of an exposure job, a finish of
the exposure job and a start of a subsequent exposure job, and
wherein said control means is arranged to cause said circulating
means to continue the laser gas circulating operating from a start
to a finish of the exposure job and to stop said circulating means
from a finish of an exposure job to a start of a subsequent
exposure job.
36. An apparatus according to claim 35, further comprising a
blower, and detecting means for detecting the number of rotations
of said blower, wherein the exposure job is interrupted when the
number of blower rotations involves a disorder.
37. A semiconductor manufacturing method, comprising: a process of
producing a semiconductor device upon a substrate by use of an
exposure apparatus as recited in claim 35.
38. An exposure apparatus having an exposure job to be executed for
exposure of a plurality of substrates, said apparatus comprising: a
laser light source including (i) a chamber for confining a laser
gas therein, (ii) a discharging electrode for exciting the laser
gas through electrical discharge so that laser light is outputted
from said chamber, and (iii) circulating means for circulating the
laser gas inside said chamber so that the laser gas passed through
an electrical discharging region of said discharging electrode is
circulated within said chamber and returns back to the electrical
discharging region of said discharging electrode; an exposure
apparatus major assembly arranged to perform exposure by use of
laser light from said laser light source; and control means for
controlling said circulating means, wherein said control means is
operable to continuously circulate the laser gas at a first speed
with said circulating means from a start to a finish of an exposure
job, and wherein said control means is operable to circulate the
laser gas at a second speed, slower than the first speed, with said
circulating means from the finish of the exposure job to a start of
a subsequent exposure job.
39. An apparatus according to claim 38, further comprising a
blower, wherein the exposure job is interrupted in response to a
disorder in the number of blower rotations.
40. A semiconductor device manufacturing method, comprising the
step of: transferring a pattern, for manufacturing of a
semiconductor device, onto a substrate by use of an exposure
apparatus as recited in claim 38.
Description
[0001] This application is a divisional application of copending
U.S. patent application Ser. No. 09/163,402, filed Sep. 30,
1998.
FIELD OF THE INVENTION AND RELATED ART
[0002] This invention relates to a gas laser device, such as a
noble gas halide excimer laser device or an F.sub.2 laser device,
for example. In another aspect, the invention is concerned with an
exposure apparatus or a semiconductor device manufacturing method
wherein such a gas laser device is used as an exposure light
source.
[0003] In the field of semiconductor device production or other
fields, a noble gas halide excimer laser (hereinafter, simply,
"excimer laser"), which is one of the types of gas lasers, has
attracted much attention as a high power laser. As for such an
excimer laser, there are an XeCl excimer laser (308 nm wavelength),
a KrF excimer laser (248 nm wavelength), and an ArF excimer laser
(193 nm wavelength), for example. Similarly, an F.sub.2 laser (158
nm wavelength) has attracted much attention as a high power laser.
Also, semiconductor device manufacturing exposure apparatuses of
the step-and-repeat type or step-and-scan type having a KrF excimer
laser (248 nm wavelength) as an exposure light source have already
been used in practice.
[0004] In excimer lasers, a laser gas containing a noble gas and a
halogen gas is sealingly stored in a chamber, and the laser gas is
once excited by electrical discharging from an electrode, provided
in the chamber, whereby laser light is produced. Also, in F.sub.2
lasers, an F.sub.2 gas is sealingly stored in a chamber, and the
laser gas is once excited by electrical discharging from an
electrode, provided in the chamber, whereby laser light is
produced.
SUMMARY OF THE INVENTION
[0005] In such excimer lasers or F.sub.2 lasers, it is necessary to
circulate the laser gas within the chamber in order to feed the
laser gas to the electrical discharging field of the electrode. To
this end, within the chamber, there is circulating means for laser
gas circulation such as a blowing machine (blower or circulating
fan), for example. If the lifetime of the blowing machine provided
in the chamber is short, the operation of the laser has to be
stopped frequently for replacement of the laser or blowing machine
for repair of the same. In cases wherein the laser is used as a
light source in an exposure apparatus, it largely affects the
productivity of the apparatus. Since the blowing machine is
disposed within the chamber, it takes much time for replacement or
repair of the same.
[0006] A factor that influences the lifetime of the blowing machine
may be the lifetime of bearing means for holding a rotational shaft
of blowing fans of the blowing machine. Generally, the lifetime of
such bearing means is shorter with a larger load applied, in
operation. Therefore, if the number of revolutions of the blowing
fans is enlarged to increase the blowing power of the blowing
machine, with a result of enlargement of the load applied to the
bearing means for supporting the rotational shaft, it accelerates
wear and shortens the lifetime of the bearing. Namely, if the
blades of the blowing machine are rotated at a high speed for high
frequency laser oscillation, the lifetime of the bearing means for
supporting the blade rotational shaft of the blowing machine is
shortened.
[0007] However, in an exposure apparatus having an excimer laser,
for example, as an exposure light source, normally, it is required
that the excimer laser be oscillated at a high frequency for
improved processing performance of the apparatus. Therefore, it is
not practical to use the blowing machine at its low blowing power
level for prolongation of the lifetime of the bearing. On the other
hand, for the reasons described above, if replacement or repair of
the excimer laser or the blowing machine occurs frequently, in an
exposure apparatus having an excimer laser as an exposure light
source, it leads to decreased productivity or throughput.
[0008] Further, in gas laser devices, the lifetime of the blowing
machine disposed in the chamber where the laser gas is stored
should be longer than the lifetime of at least the chamber.
[0009] It is accordingly an object of the present invention to
provide a gas laser device having a long lifetime and a high
power.
[0010] It is another object of the present invention to provide an
exposure apparatus or a device manufacturing method that use such a
gas laser device as an exposure light source, whereby high
productivity is assured.
[0011] In accordance with an aspect of the present invention, there
is provided a gas laser device, comprising a chamber for sealingly
storing a laser gas therein, a discharging electrode for exciting
the laser gas through electrical discharging, so that laser light
is outputted from said chamber, circulating means for circulating
the laser gas within the chamber so that the laser gas passing an
electric discharging region of the discharging electrode is
circulated in the chamber and is returned to the electrical
discharging region of the discharging electrode, and control means
for controlling the circulating means so that the circulating means
provides different gas circulation capacities, being different for
an in-operation state in which the laser gas is excited by
electrical discharging from the discharging electrode and the laser
light is outputted and for a stand-by state, which differs from the
in-operation state, but in which laser light can be outputted.
[0012] The control means may be operable to stop the gas
circulation through the circulating means when the gas laser device
is in the stand-by state. The circulating means may include a
blowing machine provided within the chamber. The blowing machine
may have a blowing blade rotatably supported within the chamber.
The laser device may comprise one of a noble gas halide excimer
laser and an F.sub.2 laser. The noble gas halide excimer laser may
comprise one of an XeCl excimer laser, a KrF excimer laser, and an
ArF excimer laser.
[0013] In accordance with another aspect of the present invention,
there is provided an exposure apparatus for exposing a substrate
with laser light, comprising a laser light source having a chamber
for sealingly storing a laser gas therein, a discharging electrode
for exciting the laser gas through electrical discharging, so that
laser light is outputted from the chamber, and circulating means
for circulating the laser gas within the chamber so that the laser
gas passing an electrical discharging region of the discharging
electrode is circulated in the chamber and is returned to the
electrical discharging region of the discharging electrode, a major
assembly for exposing a substrate with laser light from the laser
light source, and control means for controlling the circulating
means so that the circulating means provides different gas
circulation capacities, being different for an in-operation state
in which the laser gas is excited by electrical discharging from
the discharging electrode and the laser light is outputted, and for
a stand-by state, which differs from the in-operation state, but in
which laser light can be outputted.
[0014] The control means may be operable to stop the gas
circulation through the circulating means when the gas laser device
is in the stand-by state. The circulating means may include a
blowing machine provided within the chamber. The blowing machine
may have a blowing blade rotatably supported within the chamber.
The laser device may comprise one of a noble gas halide excimer
laser and an F.sub.2 laser. The noble gas halide excimer laser may
comprise one of an XeCl excimer laser, a KrF excimer laser, and an
ArF excimer laser.
[0015] In accordance with a further aspect of the present
invention, there is provided an exposure apparatus, comprising a
laser light group having (i) a chamber for sealingly storing a
laser gas therein, (ii) a discharging electrode for exciting the
laser gas through electrical discharging so that laser light is
outputted from the chamber, and (iii) circulating means for
circulating the laser gas within the chamber so that the laser gas
passing an electrical discharging region of the discharging
electrode is circulated in the chamber and is returned to the
electrical discharging region of the discharging electrode, a main
assembly for exposing a substrate with the laser light from the
laser light source, and control means for controlling the
circulating means so that the circulating means provides different
gas circulation capacities, being different for an
exposure-operation state of the exposure apparatus in which
exposure of the substrate with the laser light from the laser light
source can be performed through the main assembly, and for a
non-exposure-operation state of the exposure apparatus.
[0016] The control means may be operable to increase the gas
circulation capacity of the circulating means in response to a
start of an exposure job in which the exposure operation is
performed through the main assembly. The control means may be
operable to hold gas circulation through the circulating means
stopped before a start of the exposure job. The circulating means
may include a blowing machine provided within the chamber. The
blowing machine may have a blowing blade rotatably supported within
the chamber. The laser light source may comprise one of a noble gas
halide excimer laser and an F.sub.2 laser. The noble gas halide
excimer laser may comprise one of an XeCl excimer laser, a KrF
excimer laser, and an ArF excimer laser.
[0017] In accordance with a further aspect of the present
invention, there is provided a semiconductor device manufacturing
method in which a pattern is lithographically transferred onto a
substrate by use of any one of the exposure apparatuses as
described above.
[0018] These and other objects, features and advantages of the
present invention will become more apparent upon a consideration of
the following description of the preferred embodiments of the
present invention taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic view of an exposure apparatus with a
gas laser device, according to an embodiment of the present
invention.
[0020] FIG. 2 is a longitudinal section of a chamber of the gas
laser device.
[0021] FIG. 3 is a lateral section of the chamber of the gas laser
device.
[0022] FIG. 4 is a schematic view for explaining details of a
rotational shaft of a blower.
[0023] FIG. 5 is a flow chart for explaining operation with the gas
laser device of the embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] FIG. 1 shows an exposure apparatus according to an
embodiment of the present invention. Denoted in FIG. 1 at 1 is a
main assembly of a step-and-repeat or step-and-scan exposure
apparatus, called a stepper. Denoted at 2 is a console with which
an operator, for example, can apply a job command to a control
system (not shown) in the exposure apparatus main assembly 1, for
controlling the operation of the main assembly. Denoted at 3 is a
laser light source having a gas laser device, which is based on a
noble gas halide excimer laser (called "excimer laser"), or an
F.sub.2 laser, for example. Examples of such an excimer laser may
be an XeCl excimer laser (308 nm wavelength), a KrF excimer laser
(248 nm wavelength), and an ArF excimer laser (193 nm wavelength).
The following description will be made of an example wherein the
laser light source 3 uses a noble gas halide excimer laser.
[0025] The main assembly 1 of the exposure apparatus comprises a
beam shaping optical system 4 for rectifying, into a desired beam
shape, the sectional shape of laser light from the laser light
source 3, along the path of laser light (laser beam). The main
assembly further comprises a variable ND filter 5 for adjusting the
intensity of laser light, and an optical integrator 6 for dividing
the laser light and superposing the divided beams one upon another
for uniform illuminance upon the surface of a reticle 12. The main
assembly further comprises a condenser lens 7 for collecting laser
light from the optical integrator 6, and a beam splitter 8 for
directing a portion of the laser light from the condenser lens 7
toward a photodetector 15. The main assembly further comprises a
masking blade 9 disposed at a position where the laser light is
collected by the condenser lens 7 and for regulating the range on
the reticle 12 surface to be irradiated with the laser light. The
main assembly further comprises an imaging lens 10 for forming an
image of the masking blade 9 upon the reticle 12, and a mirror 11
for directing the path of laser light toward the optical axis
direction of a projection lens 13.
[0026] The reticle 12 can be illuminated with laser light projected
by the laser light source 3 and passed through the illumination
optical system having optical components such as described above.
With this illumination, a pattern of the reticle is projected by
the projection lens (projection optical system) 13 onto one of
different exposure shot areas on a semiconductor wafer (substrate)
in a reduced scale of one-half to one-tenth, whereby the pattern is
lithographically transferred thereto. The wafer 14 can be moved
two-dimensionally along a plane perpendicular to the optical axis
of the projection lens 13, by means of a movable stage (not shown).
As the exposure of a certain shot area on the wafer is completed,
the wafer 14 is moved to the position where the pattern of the
reticle 12 is to be projected by the projection lens 13 onto a next
shot area on the wafer.
[0027] Denoted at 16 is signal processing means for processing a
photoelectrically converted signal, having been photoelectrically
converted by the photodetector 15 and corresponding to the
intensity of the laser light. Through integration of
photoelectrically converted signals, a signal for controlling the
exposure amount can be produced. A control signal obtained with the
signal processing through the signal processing means 16 is fed
back to a controller 31 of the laser light source 3. In accordance
with this control signal, the controller 31 controls the subsequent
light emission by the laser gas in the chamber 30 of the excimer
laser 3.
[0028] FIG. 2 is a longitudinal section of the chamber 30 of the
excimer laser 3. Denoted in FIG. 2 at 32 is a pair of discharging
electrodes, which are connected to a high voltage source (HV), not
shown. On the basis of the electrical discharging from the
discharging electrodes 32, the laser gas LG portion, which is
placed in the discharging region 33 between the discharging
electrodes 32 is excited, whereby laser oscillation is executed in
a known manner. The electrical discharging from the discharging
electrodes 32 is repeated periodically, such as shown in FIG. 3, so
that the excimer laser 3 provides periodic outputs or oscillation
of the laser light 40.
[0029] The laser gas LG within the chamber 30 of the excimer laser
3 is circulated in the chamber 30 in directions (counterclockwise
in FIG. 2) denoted by arrows in the drawing, by means of a blower
or circulating fan 34 of a blowing machine (circulating means),
which is provided within the chamber 30. Thus, the laser gas LG
passing the electrical discharging region 33 of the discharging
electrodes 32 is circulated in the chamber 30 and is moved back to
the discharging region 33 of the electrodes 32. During this
circulation process, the laser gas LG passes around a heat
exchanger 35 so that it is cooled to a desired temperature. Within
the heat exchanger 35, there is a flow of temperature regulating
fluid such as temperature controlled water or air, which is
supplied from a temperature adjusted fluid supplying device (not
shown) disposed outside the chamber 30.
[0030] As shown in FIG. 3, there are windows 36 and 37 before and
after the electrical discharging region 33 in the chamber 30 of the
excimer laser 3. The laser light produced at the discharging region
33 is amplified while being passed through the windows 36 and 37
and being reflected by an output window (half mirror) 38 (which is
a laser output end) and a total reflection mirror 39. A portion of
the thus amplified laser light is outputted from the output window
(half mirror) 38, whereby laser light 40 is emitted as exposure
light. During this process, the blower 34 is continuously rotated
to circulate the laser gas LG within the chamber 30, as described
above. When the laser oscillation frequency has to be increased,
the number of revolutions of a blower drum 340 (FIG. 4) of the
blower 34 is increased to enhance the blowing power of the blower
accordingly.
[0031] Around the blower drum 340, there are a number of blades
(blowing fans) 345, as shown in FIG. 2, mounted. With the rotation
of the blower drum 340, these blades 345 operate to circulate the
laser gas LG within the chamber 30. The blower drum 340 has a
rotational shaft 34, which is rotatably supported by bearing means
(rotational shaft supporting means) such as by ball bearing 342,
for example. The lifetime of the ball bearing 342 changes with the
load applied to the ball bearing 342, and the load changes with the
rotation speed or rotation time of the blower drum 340.
[0032] The operation of this embodiment will now be described with
reference to the flow chart of FIG. 5. As a voltage source for the
excimer laser 3 (laser light source) is powered on at step S0, the
sequence goes to a warming-up stage at step S2, while the laser is
kept in a laser-offstage at step S1. In the warming-up state at
step S2, the electrical discharging from the discharging electrodes
32 is not initiated, and also, the blower 34 is kept stopped. The
remaining functions are operated such that, in this state, in
response to a start of electrical discharging from the discharging
electrodes 32, the laser emission can be executed promptly.
[0033] In this stage, if at step S3 an exposure job start signal,
for example, is applied from the console 2 of FIG. 1 to the stepper
main assembly 1 and the excimer laser 3, the electrical discharging
from the discharging electrodes 32 of the excimer laser 3 is
initiated. Simultaneously, the blower 34 starts its rotation to
initiate circulation of the laser gas LG in the chamber 30. Thus,
the excimer laser is brought into a laser-on state at step S4, such
that laser light 40 is produced from the output window 38 of FIG.
3. On the other hand, within the stepper main assembly 1, a wafer
14 introduced into the main assembly 1 is taken out of a wafer
cassette, and it is placed on a wafer stage (not shown), which is
placed at an exposure position below the projection lens 13.
Additionally, after execution of a predetermined alignment
operation with respect to a reticle 12, the exposure process is
performed at step S5 by using the laser light 40 as exposure light.
The exposure operation in the stepper main assembly 1 is repeatedly
and sequentially performed until exposures of all wafers 14 set
beforehand are completed.
[0034] Until the exposure operation at step S5 is completed, the
blower 34 in the chamber 30 continues its rotation to continue its
blowing operation. During this period, at step S4, the laser
controller 31 continuously detects the rotation speed (number of
revolutions) of the blower 34. If there is any error in the number
of blower revolutions, the electrical discharging from the
discharging electrodes 32 is discontinued. Also, the blower 34
rotation is stopped. By this, the laser goes back to the warming-up
state at step S2. On that occasion, the laser controller 31 signals
the error in the laser 3 to the console 2, such that the console 2
applies a signal to the stepper main assembly 1 to stop the job
being executed, whereby the exposure operation in the stepper main
assembly 1 is stopped.
[0035] If, on the other hand, any error in the number of
revolutions is not detected, the exposure operation at step S5 is
continued, and the exposure job is performed until exposures of all
the wafers 14 set in the stepper main assembly 1 are completed.
When, at step S6, exposures of all the wafers 14 in the stepper
main assembly 1 are completed and the exposure job thereto is
accomplished, the stepper main assembly 1 signals the exposure job
completion to the console 2. In response, the console 2 signals the
exposure job completion in the main assembly 1 to the controller 31
of the laser 3. In response, the laser controller 31 stops the
blower 34 rotation and, additionally, it stops the electrical
discharging from the discharging electrodes 32, whereby laser
oscillation from the excimer laser 3 is stopped.
[0036] In this embodiment, the blower 34 rotates only in a period
in which an exposure operation is performed in the stepper main
assembly 1 or in a period in which the excimer laser 3 provides
laser light oscillation. On the other hand, in the stepper main
assembly 1, there is a job, other than the exposure job, which
necessitates oscillation of the excimer laser 3 for measurement of
illuminance non-uniformness upon a reticle 12 or a wafer 14, or for
temperature stabilization of the projection lens 13, for example.
During a period in which such a job is executed, the blower 34 is
rotated. In accordance with this embodiment of the present
invention, the period of term for replacement or repair of the
blower 34 or bearing means 342, that is, the lifetime of it, can be
prolonged. Particularly, the lifetime of the blower 34 may be made
longer than that of the chamber 30.
[0037] While the invention has been described with reference to the
structures disclosed herein, it is not confined to the details set
forth and this application is intended to cover such modifications
or changes as may come within the purposes of the improvements or
the scope of the following claims.
* * * * *