Electric heating – Metal heating – By arc
Reexamination Certificate
2001-10-17
2003-04-01
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
Reexamination Certificate
active
06541730
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for precisely cutting a flat type non-metal substrate, such as glass or silicon, into a plurality of pieces. More particularly, the present invention relates to a method and an apparatus for cutting a non-metal substrate, wherein a cutting laser beam which follows a scribing laser beam for cutting the non-metal substrate made of a non-metal material, such as glass or silicon is generated in a cutting route so that the non-metal substrate is precisely cut along the predetermined cutting route.
2. Description of the Related Art
Recently, as a semiconductor thin film manufacturing technique is developed, a semiconductor industry has technologically advanced in manufacturing high integration and high performance semiconductor articles. In the semiconductor article, tens of thousands semiconductor devices are integrated on one substrate of high purity by thin film manufacturing processes. The substrate referred to a wafer is made of single crystalline silicon, which is one of non-metal material. The semiconductor article stores data in the form of digital signals and arithmetically treats the stored data in a minute.
In addition, as an application of the semiconductor industry, a liquid crystal display (LCD) technique, which displays an image by converting an analog signal processed in a data processing unit to a digital signal, is rapidly progressed. In the liquid crystal display device, liquid crystal molecules are filled between two transparent substrates. The liquid crystal display device changes the alignment of liquid crystal molecules by applying an electric field to the liquid crystal molecules. By changing the alignment of liquid crystal molecules, optical properties of liquid crystal cells such as birefringence, circumpolarization, dichroism, light scattering, and so on, change to display various images.
The semiconductor device and the liquid crystal display device are commonly formed on a non-metal substrate, such as a silicon substrate of high purity or a glass substrate. Though the non-metal substrate is weak against the external impact, the non-metal substrate has the advantage that a plurality of semiconductor chips or a plurality of cell units formed on the wafer or on the glass substrate can be easily sliced into an individual semiconductor chip or a cell unit.
In case of the semiconductor device, hundreds of semiconductor chips are simultaneously formed on one wafer. Then, semiconductor chips are individually cut by a cutting process. After that, a packaging process is carried out with respect to the semiconductor chip thereby forming the semiconductor article.
In case of the liquid crystal display device, at least two LCD cell units are simultaneously formed on the glass substrate called as a motherboard. Then, after cutting the LCD cell unit from the motherboard by the cutting process, the cell unit is assembled with PCBs and so on.
At this time, since the cutting process is the almost final step in the manufacturing processes, the cutting fault reduces the productivity of the articles. Particularly, the motherboard used in the liquid crystal display device is made of glass and has no crystal structure. Accordingly, the motherboard is weaker than the silicon wafer. For this reason, a fine crack formed at an edge portion of the motherboard during the cutting process amplifies stress along the fine crack. This may cut undesired portions of the motherboard when executing the cutting process.
Conventionally, a diamond blade with fine diamonds fixed at a circumferential portion of a disc rotates at a high speed, on the cutting route to form a scribe line of a predetermined depth on a substrate. Then, the substrate is cracked along the scribe line by an external impact, thereby cutting the semiconductor chip or LCD cell unit from the wafer or the glass motherboard.
When cutting the substrate by using the diamond blade, a predetermined cutting margin is prepared on the wafer or the glass motherboard, limiting the number of semiconductor chips formed on the wafer if the cutting process is not precisely performed.
In case of the liquid crystal display device, a cutting plane cut by the diamond blade is roughly processed so that the stress is concentrated on the cutting plane. Accordingly, the external impact applied to the cutting plane generates crack and chipping portions in the cutting plane.
In addition, the diamond blade that generates a lot of glass particles requires separate cleaning and drying processes to remove the glass particles.
In order to solve the above problems, various cutting methods and apparatuses using a laser beam have been developed. For example, U.S. Pat. No. 4,467,168 discloses a cutting method by using a laser and a method for manufacturing articles by using the same. In addition, U.S. Pat. No. 4,682,003 discloses a method for cutting glass by using a laser beam and U.S. Pat. No. 5,622,540 discloses a method for cutting a glass substrate.
FIG. 1
shows a conventional apparatus for cutting a glass substrate by using a laser beam.
Referring to
FIG. 1
, a laser beam
1
is irradiated along a cutting route
3
of a glass motherboard
2
so as to rapidly heat the cutting route
3
. Then, a cooling fluid beam
4
having the temperature extremely lower than the temperature of the heated glass motherboard
2
is radiated along the cutting route
3
such that the glass motherboard
2
is cut along the cutting route
3
by means of the tensile force caused by the rapid expansion and shrink of the glass motherboard
2
.
The cutting apparatus shown in
FIG. 1
can cut a relatively thin glass motherboard at once. Recently, the liquid crystal display device is required to have a large size so that the surface area and the thickness of the glass motherboard become increased. Especially, the present glass motherboard has the thickness over 0.5 mm. Accordingly, in order to cut the glass motherboard having the thickness over 0.5 mm at once, the laser beam
1
is required to have the extremely high energy level.
When the energy level of the laser beam I irradiated onto the glass motherboard
2
increases, the temperature difference between the cutting route
3
of the glass motherboard
2
and a periphery portion of the cutting route
3
is greatly increased. This temperature difference creates cracks, before the cooling fluid beam
4
cools the cutting route
2
at portions of the glass motherboard
2
where the temperature difference is greatly increased, cutting undesired portions of the glass motherboard.
In order to solve the above problem, an apparatus for cutting a glass substrate without using the laser beam having the high energy level is developed. The cutting apparatus is shown in FIG.
2
.
In
FIG. 2
, a scribing laser beam
13
is irradiated along a cutting route
12
of a glass motherboard
10
so as to rapidly heat the cutting route
12
. Then, a cooling fluid beam
14
having the temperature extremely lower than the temperature of the heated glass motherboard
10
is applied along the cutting route
12
. Then, the glass motherboard
10
is rapidly cooled so that a crack having a predetermined depth is formed on the surface of the glass motherboard
10
, thereby forming a scribe line
15
. After that, both sides of the glass motherboard
10
are rapidly heated about the scribe line
15
. Accordingly, both sides of the glass motherboard
10
are rapidly expanded so that a great tensile force is generated at the scribe line
15
. As a result, the glass motherboard
10
is completely cut along the scribe line
15
.
According to the cutting apparatus as shown in
FIG. 2
, the scribe line
15
can be formed even when the temperature difference between the heated cutting route
12
and the cooled cutting route
12
is not widely formed. In addition, since a shear stress is increased as the temperature difference between the scribe line
15
and a periphery portion of the scribe line
15
is increased, the cutting apparatus can cut a relati
Choo Dae-Ho
Jeon Baek-Kyun
Nam Hyung-Woo
Heinrich Samuel M.
McGuireWoods LLP
Park Hae-Chan
Samsung Electronics Co,. Ltd.
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