U.S. patent application number 12/651703 was filed with the patent office on 2011-03-03 for metal wire structure with high-melting-point protective layer and its manufacturing method.
This patent application is currently assigned to CONTREL TECHNOLOGY CO., LTD.. Invention is credited to CHIA-LUNG KUO, MAO-CHENG LIN.
Application Number | 20110048953 12/651703 |
Document ID | / |
Family ID | 43623236 |
Filed Date | 2011-03-03 |
United States Patent
Application |
20110048953 |
Kind Code |
A1 |
KUO; CHIA-LUNG ; et
al. |
March 3, 2011 |
METAL WIRE STRUCTURE WITH HIGH-MELTING-POINT PROTECTIVE LAYER AND
ITS MANUFACTURING METHOD
Abstract
The present invention presents a metal wire structure with
high-melting-point protective layer and its manufacturing method,
of which the structure comprising: a core and a protective layer;
the core is made of metal, and the protective layer made of metal
carbide or metal nitride. The manufacturing method includes the
following steps: preparation, discharge and finish. The protective
layer is gradually bonded onto the exterior surface of the core
until a preset thickness of the protective layer, and then fully
covered onto the core through a plating process of discharge
reaction at temperature over 5000.quadrature.. With this design,
the present invention has advantages and efficacies such as:
without generation of silicide and producing protective
effects.
Inventors: |
KUO; CHIA-LUNG; (YUNLIN
COUNTY, TW) ; LIN; MAO-CHENG; (CHANGHUA CITY,
TW) |
Assignee: |
CONTREL TECHNOLOGY CO.,
LTD.
TAINAN COUNTY
TW
|
Family ID: |
43623236 |
Appl. No.: |
12/651703 |
Filed: |
January 4, 2010 |
Current U.S.
Class: |
205/50 ;
205/149 |
Current CPC
Class: |
C25D 7/0607
20130101 |
Class at
Publication: |
205/50 ;
205/149 |
International
Class: |
C25D 7/06 20060101
C25D007/06 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 31, 2009 |
TW |
098129257 |
Claims
1. A manufacturing method of metal wire structure with
high-melting-point protective layer comprising the following steps:
preparation step: preparing a core and a discharge device, of which
the core in a threaded shape is made of metal material; said
discharge device being provided with a positive electrode, a
negative electrode, a discharge reaction tank, a discharge
processing medium, an electrode fixed portion and a discharge
reaction member; said discharge processing medium being placed into
said discharge reaction tank, said electrode fixed portion being
used to fix said core, which is linked to said negative electrode;
said discharge reaction member made of metal being linked to said
positive electrode; a preset discharge gap being defined between
said core and said discharge reaction member, and filled with said
discharge processing medium; said discharge processing medium
consisting of either carbon atom or nitrogen atom; discharge step:
said discharge device being activated to enable electrical
discharge of said core and said discharge reaction member; a local
temperature in this discharge process being over 5000.quadrature.,
so metal atoms of said core impinging dispersedly on an exterior
surface of said discharge reaction member, meanwhile the metal
atoms of said discharge reaction member being combined with atoms
in said discharge processing medium, and impinging dispersedly on
said exterior surface of said core, so a protective layer being
gradually formed on said exterior surface of said core; finish
step: a metal wire structure with high-melting-point protective
layer being made which comprises: a core which is made of metal
material and is shaped as a thread; a protective layer which is
made of either metal carbide or metal nitride; said protective
layer being gradually bonded onto an exterior surface of said core
until a preset thickness, and then fully covered onto said core
through a plating process of discharge reaction at temperature over
5000.quadrature..
2. The method defined in claim 1, wherein said discharge reaction
member is made of W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn
tungsten alloy, platinum alloy, palladium alloy, molybdenum alloy,
titanium alloy, niobium alloy, tantalum alloy, cobalt alloy, nickel
alloy, chrome alloy, or manganese alloy.
3. A metal wire structure with high-melting-point protective layer
comprising: a core which is made of metal material and is shaped as
a thread; a protective layer which is made of either metal carbide
or metal nitride; said protective layer being gradually bonded onto
an exterior surface of said core until a preset thickness, and then
fully covered onto said core through a plating process of discharge
reaction at temperature over 5000.quadrature..
4. The structure defined in claim 3, wherein said core is made of
W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn, tungsten alloy, platinum
alloy, palladium alloy, molybdenum alloy, titanium alloy, niobium
alloy, tantalum alloy, cobalt alloy, nickel alloy, chrome alloy, or
manganese alloy.
5. The structure defined in claim 3, wherein said protective layer
is made of metal carbide containing W, Pt, Pd, Mo, Ti, Nb, Ta, Co,
Ni, Cr, Mn, tungsten alloy, platinum alloy, palladium alloy,
molybdenum alloy, titanium alloy, niobium alloy, tantalum alloy,
cobalt alloy, nickel alloy, chrome alloy, or manganese alloy.
6. The structure defined in claim 3, wherein said protective layer
is made of metal nitride containing W, Pt, Pd, Mo, Ti, Nb, Ta, Co,
Ni, Cr, Mn, tungsten alloy, platinum alloy, palladium alloy,
molybdenum alloy, titanium alloy, niobium alloy, tantalum alloy,
cobalt alloy, nickel alloy, chrome alloy, or manganese alloy.
Description
BACKGROUND OF INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to a metal wire
structure with high-melting-point protective layer and its
manufacturing method, and more particularly to an innovative one
which prevents the generation of silicide and produces protective
effect.
[0003] 2. Description of Related Art
[0004] The conventional Hot Wire Chemical Vapor Deposition (HWCVD)
and Plasma Enhanced Chemical Vapor Deposition (PECVD) are widely
applied to the manufacturing processes of various films, including:
semi-conductors, liquid crystal display (LCD) panels and solar
panels, helping to form a thin film on a substrate. Such film is
made of Amorphous Silicon (a-Si) or other components (depending on
the reactant gases supplied).
[0005] The major disadvantages of PECVD include: low deposition
rate, low productivity, longer deposition time and cost. The
disadvantages of HWCVD include: difficult to control the
concentration of free radical or the filament temperature, and
lower film quality.
[0006] FIG. 1 depicts a hybrid chemical vapor deposition combining
HWCVD and PECVD (patent No. WO 2009/2009499). Of which, a closed
reaction chamber 810 comprises: a reaction space 820, a plasma
generating unit 830, a hot wire device 840, a substrate 850, a
substrate carrier 860, a heater 870, a substrate feeder 875 and a
substrate discharger 880. The plasma generating unit 830 is used to
generate plasma-excited atoms of vapor chemicals, and the hot wire
device 840 is used to generate thermally-excited atoms of vapor
chemicals. For instance, the mixture of hydrogen (H.sub.2) and
silicon hydride (SiH.sub.4) is fed into the reaction space 820 at
1:100; the hot wire device 840 is heated to 1850.degree. C., the
plasma generating unit 830 generates the energy of 25 w/100
cm.sup.2 for the substrate, and the heater 870 maintains the
temperature of 400.degree. C. With the use of HWCVD and PECVD, a-Si
film can be generated on the substrate 850.
[0007] FIG. 2 depicts another conventional HWCVD technique (patent
No. EP1986242A2), which comprises: a reaction chamber 91, a gas
feed portion 92, a direct current (DC) power supply 93, a catalytic
hot wire 94, an exhaust valve 95, a carrier platform 96 and a
heater 97. The carrier platform 96 is provided with a bottom layer
920, which can be heated by the heater 97; a film 910 is gradually
formed on the bottom layer 920.
[0008] However, both hot wire device 840 and catalytic hot wire 94
are made of pure tungsten; when silicon hydride (SiH.sub.4) is
filled into the reaction space 820 and the reaction chamber 91, and
the temperature of hot wire device 840 or catalytic hot wire 94
hasn't reached the melting point of silicon (about 1410.degree.
C.), the gas will contact with the hot wire device 840 or catalytic
hot wire 94, but cannot be fully decomposed, with some residual gas
left on the surface of hot wire device 840 or catalytic hot wire
94. Then, the silicide (e.g. tungsten silicide) is formed, leading
to change of the filament resistance. Take catalytic hot wire 94,
for example, FIGS. 3A and 3B depicts the outside view of the
catalytic hot wire 94 without and with silicide respectively,
whilst FIGS. 4A and 4B depicts the partially enlarged sectional
view of the surface of catalytic hot wire 94 without or with
silicide respectively. It can be clearly seen that, when silicide
941 is formed on the surface of the catalytic hot wire 94, silicide
941 may generate many cracks 942 due to expansion and contraction,
as the surface temperature of the catalytic hot wire 94 is at
normal temperature in idle state, or at 1850.degree. C. in
operating state. In addition, when the silicide 941 is fully
covered onto the catalytic hot wire 94, the function of the
catalytic hot wire 94 will be lost, affecting the process of hot
wire chemical vapor deposition seriously.
[0009] Hence, it is important to know how to prevent generation of
silicide with fed gas when the temperature of tungsten filament
(either hot wire device 840 or catalytic hot wire 94) increases
from normal temperature to 1850.degree. C.
[0010] Thus, to overcome the aforementioned problems of the prior
art, it would be an advancement if the art to provide an improved
structure that can significantly improve the efficacy.
SUMMARY OF INVENTION
[0011] The object of the present invention is to provide a metal
wire structure with high-melting-point protective layer and its
manufacturing method, which prevents the generation of silicide and
produces protective effect to resolve the shortcomings of prior
art.
[0012] In order to achieve the above mentioned object, this
invention is provided. A manufacturing method of metal wire
structure with high-melting-point protective layer comprising the
following steps:
[0013] preparation step: preparing a core and a discharge device,
of which the core in a threaded shape is made of metal material;
the discharge device being provided with a positive electrode, a
negative electrode, a discharge reaction tank, a discharge
processing medium, an electrode fixed portion and a discharge
reaction member; the discharge processing medium being placed into
the discharge reaction tank, the electrode fixed portion being used
to fix the core, which is linked to the negative electrode; the
discharge reaction member made of metal being linked to the
positive electrode; a preset discharge gap being defined between
the core and the discharge reaction member, and filled with the
discharge processing medium; the discharge processing medium
consisting of either carbon atom or nitrogen atom;
[0014] discharge step: the discharge device being activated to
enable electrical discharge of the core and the discharge reaction
member; a local temperature in this discharge process being over
5000.degree. C., so metal atoms of the core impinging dispersedly
on an exterior surface of the discharge reaction member, meanwhile
the metal atoms of the discharge reaction member being combined
with atoms in the discharge processing medium, and impinging
dispersedly on the exterior surface of the core, so a protective
layer being gradually formed on the exterior surface of the
core;
[0015] finish step: a metal wire structure with high-melting-point
protective layer being made which comprises: [0016] a core which is
made of metal material and is shaped as a thread; [0017] a
protective layer which is made of either metal carbide or metal
nitride; the protective layer being gradually bonded onto an
exterior surface of the core until a preset thickness, and then
fully covered onto the core through a plating process of discharge
reaction at temperature over 5000.degree. C.
[0018] About the structure of this invention, a metal wire
structure with high-melting-point protective layer comprises:
[0019] a core which is made of metal material and is shaped as a
thread;
[0020] a protective layer which is made of either metal carbide or
metal nitride; the protective layer being gradually bonded onto an
exterior surface of the core until a preset thickness, and then
fully covered onto the core through a plating process of discharge
reaction at temperature over 5000.quadrature..
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 shows a schematic view of the first prior art.
[0022] FIG. 2 shows a schematic view of the second prior art.
[0023] FIG. 3A shows a perspective view that no silicide is formed
on the surface of conventional catalytic hot wire.
[0024] FIG. 3B shows a perspective view that silicide is already
formed on the surface of conventional catalytic hot wire.
[0025] FIG. 4A shows a partially enlarged sectional view that no
silicide is formed on the surface of conventional catalytic hot
wire.
[0026] FIG. 4B shows a partially enlarged sectional view that
silicide is already formed on the surface of conventional catalytic
hot wire.
[0027] FIG. 5 is a view illustrating the present invention.
[0028] FIG. 6 shows a flow chart of the present invention.
[0029] FIG. 7 shows a schematic view of the processing system of
the present invention.
[0030] FIG. 8 shows a partially enlarged view of FIG. 7.
[0031] FIG. 9A shows a schematic view of the first discharge
process of the present invention.
[0032] FIG. 9B shows a schematic view of the second discharge
process of the present invention.
[0033] FIG. 9C shows a schematic view of the third discharge
process of the present invention.
[0034] FIG. 10 shows a schematic view that the structure of the
present invention is applied to HWCVD device.
[0035] FIG. 11 shows another schematic view that the structure of
the present invention is applied to HWCVD device.
[0036] FIG. 12 shows a partially enlarged view that the structure
of the present invention is applied to HWCVD device.
[0037] FIG. 13 shows an appearance view of common tungsten
filament.
[0038] FIG. 14 shows an appearance view of the present
invention.
[0039] FIG. 15 shows a partially enlarged view of the present
invention.
[0040] FIG. 16 shows an EDS analysis view of the protective layer
of the present invention.
[0041] FIG. 17 shows a schematic view that common tungsten filament
is heated to 600.degree. C.
[0042] FIG. 18 shows a schematic view that the present invention is
heated to 600.degree. C.
[0043] FIGS. 19A, 19B, 19C and 19D show the surface the metal wire
structure with high-melting-point protective layer after completion
of discharge that is amplified to 25 times, 50 times, 100 times and
200 times respectively.
DETAILED DESCRIPTION OF THE INVENTION
[0044] The present invention relates to a metal wire structure with
high-melting-point protective layer and its manufacturing method.
Referring to FIG. 5, the metal wire structure 100 of the present
invention with high-melting-point protective layer comprises:
[0045] a core 20, which is made of metal material and is shaped as
a thread;
[0046] a protective layer 30, which is made of either metal carbide
or metal nitride; the protective layer 30 is gradually bonded onto
the surface of the core 20 until a preset thickness, and then fully
covered onto the core 20 through a plating process of discharge
reaction at temperature over 5000.degree. C.; moreover, the cross
section of the core 20 is of round (shown in FIG. 5), rectangular,
flat or other geometric shapes.
[0047] Referring to FIG. 6, the manufacturing method of the present
invention includes the following steps:
[0048] preparation step 11: preparing a core 20 and a discharge
device 40, of which the core 20 in a threaded shape is made of
metal material; the discharge device 40 is provided with a positive
electrode 41, a negative electrode 42, a discharge reaction tank
43, a discharge processing medium 44, an electrode fixed portion 45
and a discharge reaction member 46; the discharge processing medium
44 is placed into the discharge reaction tank 43, the electrode
fixed portion 45 is used to fix the core 20, which is linked to the
negative electrode 42; the discharge reaction member 46 made of
metal is linked to the positive electrode 41; a preset discharge
gap S is defined between the core 20 and the discharge reaction
member 46, and filled with the discharge processing medium 44;
furthermore, the discharge processing medium 44 consists of either
carbon atom or nitrogen atom;
[0049] discharge step 12: the discharge device 40 is activated to
enable electrical discharge of the core 20 and the discharge
reaction member 46; referring to FIGS. 9 A, 9B and 9C, the local
temperature in this discharge process is over 5000.degree. C., so
metal atoms of the core 20 impinge dispersedly on an exterior
surface of the discharge reaction member 46, meanwhile the metal
atoms of the discharge reaction member 46 are combined with the
atoms of the discharge processing medium 44 (i.e. carbon or
nitrogen atoms), and impinge dispersedly on the exterior surface of
the core 20, so a protective layer 30 is gradually formed on the
exterior surface of the core 20;
[0050] finish step 13: a metal wire structure 100 with
high-melting-point protective layer is made which comprises:
[0051] a core 20, made of metal material and shaped as a
thread;
[0052] a protective layer 30, made of either metal carbide or metal
nitride; the protective layer 30 is gradually bonded onto the
surface of the core 20 until a preset thickness of protective
layer, and then fully covered onto the core 20 through a plating
process of discharge reaction at temperature over 5000.degree.
C.
[0053] More specifically, the core 20 is made of W, Pt, Pd, Mo, Ti,
Nb, Ta, Co, Ni, Cr, Mn or tungsten alloy, platinum alloy, palladium
alloy, molybdenum alloy, titanium alloy, niobium alloy, tantalum
alloy, cobalt alloy, nickel alloy, chrome alloy, or manganese
alloy. The protective layer 30 is made of either metal carbide or
metal nitride containing W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn,
tungsten alloy, platinum alloy, palladium alloy, molybdenum alloy,
titanium alloy, niobium alloy, tantalum alloy, cobalt alloy, nickel
alloy, chrome alloy, or manganese alloy (e.g.: TiC, TaC, TiN, WC
and CrC).
[0054] In addition, the core 20 and the protective layer 30 can be
made of materials with similar thermal expansion coefficient so as
to prevent the bonding relation due to thermal expansion. For
example: when the core 20 is made of tungsten, the expansion
coefficient is about 4.6 (10.sup.-6/.degree. C.), and the
protective layer 30 can be made of WC or TiC, with the thermal
expansion coefficient of WC approx. 3.7 to 5.7 (10.sup.-6/.degree.
C.), and that of TiC approx. 5.5 (10.sup.-6/.degree. C.), showing a
similar thermal expansion coefficient of the core 20 and the
protective layer 30.
[0055] It is assumed that the discharge reaction member 46 is made
of titanium, and the discharge processing medium 44 is a solution
containing carbon atom; the key feature of the present invention
lies in the discharge mechanism, whereby a temperature over
5000.degree. C. is generated during the discharge process, so that
the titanium atom of the discharge reaction member 46 and the
carbon atom in the discharge processing medium 44 are combined into
TiC impinging on the electrode (tungsten is assumed), and closely
bonded onto the electrode to form gradually a thin TiC protective
layer. The bonding process among atoms presents excellent
compactness. In other words, when the metal wire structure 100 of
the present invention with a high-melting-point protective layer
(it is assumed that the core 20 is made of tungsten), the operating
temperature of the energized tungsten filament is about
1850.degree. C..about.2100.degree. C., much lower than the
temperature generated by TiC protective layer. So, the TiC
protective layer no longer reacts with the reactant gas (e.g.
silicon hydride or hydrogen), nor generates silicide. Certainly,
the discharge processing medium 44 is also a kind of gas containing
nitrogen atom (e.g.: N.sub.2), so that the carbon and nitrogen
atoms are combined into TiN impinging on the electrode, and closely
bonded onto the electrode to form gradually a thin TiN protective
layer.
[0056] In addition, as for the metal wire structure 100 with
high-melting-point protective layer after completion of discharge,
the surface is shown in FIGS. 19A, 19B, 19C and 19D, wherein the
surface is amplified to 25 times, 50 times, 100 times and 200
times.
[0057] The present invention can be applied to a HWCVD device
(namely, the catalytic hot wire 94 of prior art can be replaced as
a metal wire structure 100 of the present invention with a
high-melting-point protective layer); referring to FIGS. 10, 11 and
12, when silicon hydride (SiH.sub.4) (shown by the arrow) is filled
into the reaction chamber 91, and the temperature of the core 20
hasn't reached the melting point of silicon (about 1410.degree.
C.), the protective layer 30 can protect the core 20 not to contact
with gas (the melting point of the protective layer 30 is over
5000.degree. C.). Hence, it helps to resolve the shortcomings of
prior art that gas cannot be fully decomposed, with some residual
gas left on the surface of catalytic hot wire 94 (i.e. generation
of silicide).
[0058] The products of the present invention can be used in some
applications such as:
[0059] [a] Example one: the metal wire structure with
high-melting-point protective layer is heated up, then the reactant
gas passing through the surface of the protective layer 30 is
heated to generate free radical, allowing for technical
applications for cleaning the surface of Si, Al and TiN, as well as
copper film (i.e. Cu film), etc. The reactant as can be selected
optionally from any group of hydrogen (H.sub.2), ammonia
(NH.sub.3), silicon hydride (SiH.sub.4), hydrazine
(NH.sub.2NH.sub.2) and water (H.sub.2O). For instance, if the
reactant gas is hydrogen (H.sub.2) or vapor (H.sub.2O), it can
generate free radical of H atom, if the reactant gas is ammonia
(NH.sub.3), it can generate free radical of NH and NH.sub.2
atoms.
[0060] [b] Example two; the metal wire structure with
high-melting-point protective layer is heated up, then the reactant
gas (CH.sub.4) passing through the surface of the metal wire is
heated to generate free radical (C atom, etc), allowing for DLC
(Diamond-Like Carbon) plating.
[0061] The actual test results of the present invention are
described below:
[0062] FIGS. 13 and 14 depict separately the perspective view of
conventional tungsten filament and the present invention. FIG. 15
depicts a partially enlarged view of the present invention, wherein
2.about.3 .mu.m protective layer 30 of the present invention can be
clearly observed.
[0063] FIG. 16 depicts EDS (Energy Dispersive Spectrometer)
analysis of the protective layer 30, of which carbon atom is 67%,
titanium atom 3% and tungsten atom 30%, proving the covering effect
of the protective layer 30.
[0064] Vickers hardness test results indicate that, the hardness of
common tungsten filament is HV400, but that of the present
invention increases to HV700; common tungsten filament will be
softened when it is heated electrically (DC) up to 600.degree. C.
(shown in FIG. 17), but the present invention lacks of such
phenomenon when it is heated up to 600.degree. C. (shown in FIG.
18).
[0065] In addition, the temperature distribution of common tungsten
filament is shown in Table 1 and FIG. 17 (serial number of
positions in Table 1 corresponds to that of positions A1.about.A14
in FIG. 17). It can be seen that, the temperature distribution of
common tungsten filament is extremely uneven (high temperature
concentrated at right side). However, the temperature distribution
of the present invention is shown in Table 2 and FIG. 18 (serial
number of positions in Table 2 corresponds to that of positions
B1.about.B14). It can be seen that, the temperature distribution of
the present invention is even.
TABLE-US-00001 TABLE 1 Temperature distribution of common tungsten
filament Serial No of positions Temperature(.degree. C.) Point A1
596 Point A2 580 Point A3 552 Point A4 511 Point A5 492 Point A6
490 Point A7 507 Point A8 518 Point A9 328 Point A10 338 Point A11
57 Point A12 68 Point A13 44 Point A14 42
TABLE-US-00002 TABLE 2 Temperature distribution of the present
invention Serial No of positions Temperature(.degree. C.) Point B1
606 Point B2 600 Point B3 603 Point B4 596 Point B5 598 Point B6
600 Point B7 598 Point B8 577 Point B9 104 Point B10 68 Point B11
49 Point B12 33 Point B13 35 Point B14 29
[0066] It is proved experimentally that, in an oxygen-bearing
environment, if the catalytic hot wire 94 of prior art is made of
tungsten, and the temperature is about 1000.degree.
C..about.2000.degree. C., wire rupture may occur; but, due to the
protective layer 30, the core 20 of the present invention will not
rupture in an oxygen-bearing environment at 1000.degree.
C..about.2000.degree. C.
[0067] The advantages and efficacies of the present invention can
be summarized below:
[0068] 1. Without generation of silicide. In the prior art, when
silicon hydride (SiH.sub.4) contacts with hot wire device 840 or
catalytic hot wire 94 whose temperature hasn't reached the melting
point of silicon (about 1410.degree. C.), the gas cannot be fully
decomposed, with some residual gas left on the surface of hot wire
device 840 or catalytic hot wire 94. Namely, silicide 941 is
formed. When the silicide 941 is fully covered onto the catalytic
hot wire 94, the function of the catalytic hot wire 94 will be
lost, affecting the process of hot wire chemical vapor deposition
seriously. With the use of discharge processing method, a
protective layer 30 is formed on the exterior surface of the core
20, thus maintaining the function of the core 20 and preventing
reaction of gas with the core 20 against generation of silicide
941.
[0069] 2. Producing protective effects. In the prior art, the
silicide 941 is prone to form many cracks 942 due to expansion and
contraction, affecting the function and service life of the
catalytic hot wire 94; with the use of protective layer 30, the
present invention can prevent the forming of silicide 941 on the
core 20 for realizing the protective effects.
[0070] The aforementioned description of the preferred embodiments
shows that the present invention can really meet the
above-specified purpose and patent specifications, so the patent
application is claimed herein.
[0071] Although the invention has been explained in relation to its
preferred embodiment, it is to be understood that many other
possible modifications and variations can be made without departing
from the spirit and scope of the invention as hereinafter
claimed.
* * * * *