WO2006036038A1

WO2006036038A1 - Laser processing apparatus and method using tec module

Info

Publication number: WO2006036038A1
Application number: PCT/KR2004/003064
Authority: WO
Inventors: You-Hie Han; Eun-Jeong Hong; Tae-Hyun Kim; Dong-Jun Lee
Original assignee: Eo Technics Co., Ltd.
Priority date: 2004-09-30
Filing date: 2004-11-25
Publication date: 2006-04-06
Also published as: KR100514995B1

Abstract

The object of the present invention is to provide a laser processing apparatus and method, capable of minimizing incurred costs and produced pollutants when processing an object using a laser. The apparatus includes a chuck (30) to hold the object loaded into a chamber. A TEC module (40) is provided on a lower surface of the chuck to cool the object, thus forming a frozen layer on a surface of the object. An insulation means (50) is provided on a lower surface of the TEC module. A laser generating means (120) generates a laser beam. A reflecting means (130) reflects the laser beam onto the object. This invention can process the object with minimal expense, simplify the operation of processing an object, and allows particles produced during the laser process to be easily removed by a cleaning process, thus preventing environmental pollution.

Description

LASER PROCESSING APPARATUS AND METHOD USING TEC MODULE

Technical Field

The present invention relates, in general, to a laser processing apparatus and method and, more particularly, to a laser processing apparatus and method using a thermoelectric cooling module, capable of minimizing incurred costs and produced pollutants when processing an object using a laser.

Background Art

Generally, several processes, including cutting and grooving, are required to manufacture a desired product using various materials, such as wafers, metals, or plastics. For example, after a semiconductor manufacturing process has been completed, an operation of cutting a plurality of chips formed on a wafer is followed to separate the chips from each other. Since the cutting operation considerably affects the quality and productivity of subsequent processes, the cutting operation is very important. Currently, a mechanical cutting method, a cutting method using a laser, and other cutting methods are used to cut the wafer. Particularly, a processing apparatus using a laser has many advantages compared to a mechanical apparatus, so that research into processing apparatuses using lasers has been steadily carried out.

Wafer cutting using a laser is performed as follows. That is, a laser beam of a high ultraviolet range (25O~360nm) is focused onto a surface of the wafer, thus leading to a heating action and a chemical change, thereby eliminating a laser focusing region. In a detailed description, when the laser beam is focused and irradiated onto a region of the wafer, the temperature of the laser focusing region rises instantaneously. According to a beam irradiation degree, the wafer material is melted or sublimated. As the material evaporates, pressure increases, thus explosively eliminating the laser focusing region. Such an elimination is continuously performed so that the wafer is cut.

Further, this method has an advantage in that the wafer is cut in a straight line or a curved line, according to a moving course of the laser. FIGS. IA and IB are views illustrating a conventional laser processing method.

When a laser beam is irradiated onto a predetermined position on an object 10, as shown in

FIG. IA, a laser focusing region A of the object 10 is eliminated, as shown in FIG. IB. The laser irradiation time period is controlled according to the intended purpose, so that the object 10 is cut or grooved. When the laser focusing region A of the object 10 is grooved to a desired depth or is cut, particles B are produced at the laser focusing region A. The particles B come into contact with a surface of the object 10, thus affecting performance of the object 10. Further, when the object 10 is cleaned to get rid of the particles B, the object 10 is exposed to a cleaning material, so that the object

10 may have a defect. In order to solve the problem, a method of coating the surface of the object 10 has been proposed, prior to processing the object 10 using the laser beam. This method will be described below with reference to FIG.2.

FIGS. 2A to 2D are views illustrating a method of processing an object using a laser, after coating the object. As shown in FIG. 2A, first, a coating layer 20 is formed on the object 10 to be processed.

Preferably, the coaling layer 20 is made of a water soluble material for a subsequent cleaning process.

Further, it is preferable that the coating layer 20 be made of material having an excellent laser absorption capacity.

After forming the coating layer 20, as shown in FIG. 2B, a laser beam is irradiated onto a predetermined position of the object 10. When the laser beam is irradiated as such, particles B are produced at a laser focusing region A. As shown in FIG.2C, the particles B come into contact with the surface of the coating layer 20.

Subsequently, the cleaning process is executed to eliminate the coating layer 20 and the particles B, so that a finished object 10 is obtained, as shown in FIG. 2D. However, the particles B produced while processing the object 10 are present in the cleaning solution which is used to clean the coating layer 20. In order to remove the particles B, a filter is additionally required.

Further, since the object 10 must be coated and cleaned using additional materials, the installation and maintenance of a coating device and a cleaning device are required. Thus, the processing method is very complicated, and productivity is reduced, therefore manufacturing costs are increased. Further, vibration may occur during the coating and cleaning processes, and the coating and cleaning processes may corrode the object, so that additional precautionary measures are required.

Disclosure of the Invention

Accordingly, the present invention has been made to solve the above problems in the prior art, and an object of the present invention is to provide a laser processing apparatus and method using a thermoelectric cooling module, which freezes a surface of an object using water y^apor in a process chamber, thus forming a frozen layer, and uses the frozen layer as a coating layer, when the object is processed using a laser, thus simplifying the process procedures.

Another object of the present invention is to provide a laser processing apparatus and method using a thermoelectric cooling module, which forms a frozen layer on an object, eliminates the frozen layer after processing the object, and collects particles eliminated together with the frozen layer using a filter, thus minimizing industrial waste water. In order to accomplish the above object, the present invention uses vapor condensation and vapor freezing phenomena that occur due to the temperature difference between an object and its surroundings. That is, when an object to be processed is cooled, a frozen layer is formed on a surface of the object due to a temperature difference between a process chamber and the object. The frozen layer is utilized as a coating layer when processing the object using a laser, so that by-products which are produced in the processing of the object are attached to the frozen layer. When the object has been processed, the frozen layer is eliminated by a wet or dry process. At this time, the by¬ products eliminated together with the frozen layer are additionally filtered and collected. Therefore, the present invention is capable of reducing costs incurred by a coating process and a cleaning process, and efficiently treating waste water problem. According to the present invention, an object is cooled by a thermoelectric cooling module, and water vapor contained in a chamber is freezed on a surface of the object, to be utilized as a coating layer, thereby efficient processing without major expense can be carried out.

Brief Description of the Drawings

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description in conjunction with the accompanying drawings, in which:

FIGS. IA and IB are views illustrating a conventional laser processing method; FIGS.2A and 2D are views illustrating a method of processing an object using a laser, after coating the object to be processed;

FIG. 3 is a block diagram illustrating the construction of a laser processing apparatus, according to the present invention;

FIG. 4 is a view illustrating the construction of a thermoelectric cooling module adapted to the present invention; FIG. 5 is a flow chart illustrating a laser processing method, according to the present invention; and

FIGS. 6A to 6D are views illustrating an example of processing an object by the laser processing method, according to the present invention.

Best Mode for Carrying Out the Invention

Hereinafter, the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 3 is a view illustrating the construction of a laser processing apparatus, according to the present invention.

As shown in the drawing, the laser processing apparatus 100 includes a control unit 110, a laser generating means 120, a reflecting means 130, an input unit 140, a display unit 150, and a storage unit 160. The control unit 110 controls the entire operation of the laser processing apparatus. The laser generating means 120 generates a laser beam having a predetermined caliber. The reflecting means 130 changes the direction of the laser beam generated by the laser generating means 120, thus focusing the laser beam onto a predetermined position of an object 10, such as a wafer. The input unit 140 is used to input a control parameter and a control instruction. The display unit 150 displays information, such as an operational state. The storage unit 160 serves to store data. The laser processing apparatus 100 also includes a sensor 170, a humidifying means 180, a deicing means 200, a chuck 30, a thermoelectric cooling module 40 which will be hereinafter referred to as a TEC module, and an insulation means 50. The chuck 30, the TEC module 40, and the insulation means 50 form a stage on which the object 10 is supported. The sensor 170 detects the temperature and humidity in a chamber 190. The humidifying means 180 supplies moisture to the air in the chamber 190 to increase the humidity in the chamber 190. The deicing means 200 serves to melt a frozen layer to be deposited on the object 10. The object 10, such as a wafer, adheres to and is held by the chuck 30. The TEC module 40 is used to cool the chuck 30. Further, the insulation means 50 prevents several mechanical units, including a coupling member 60, from being cooled by the TEC module 40. The coupling member 60 is coupled to, for example, a stage conveying means (not shown) to convey the stage having the object 10 while processing the object 10.

In this case, the TEC module 40 is a functional electronic element which directly changes heat energy to electric energy or change electric energy to heat energy. The. TEC module 40 is also known as a Peltier element. The Peltier element serves as a themial engineering element to transfer heat from a heat absorbing part to a heat evolving part. The Peltier element is advantageous in that conversion from a cooling operation to a heating operation is allowed by changing a thermoelectric direction, and the Peltier element is controlled not by an on/off control but by voltage or current, so that fine temperature control is possible. Further, since the Peltier element has no moving parts, no vibration or noise are generated. Furthermore, the Peltier element does not use a Freon refrigerant, so that pollution is prevented. FIG. 4 is a view illustrating the construction of the TEC module adapted to the preset invention.

As shown, in the drawing, the TEC module 40 includes lower conductive layers 420 and upper conductive layers 422 between a lower substrate 410 and an upper substrate 412. Further, semiconductor chips 430 are provided between the lower conductive layers 420 and the upper conductive layers 422. As electricity is supplied to power supply cables 440 and 442, a cooling operation is executed.

In this case, the lower and upper substrates 410 and 412 serve to limit the flow of electricity, in addition to efficiently transmitting heat. The lower and upper conductive layers 420 and 422 and the semiconductor chips 430 actually act as a cooling engine. Further, the semiconductor chips 430 are arranged such that P-type semiconductors and N-type semiconductors are connected to each other in series, thus maximizing cooling efficiency.

As the TEC module 40 begins the cooling operation, the chuck 30 provided on the TEC module 40 is cooled. As a result, the temperature of the object 10 is lowered. Because the interior of the chamber 190 is at room temperature, as the temperature of the object 10 is lowered, water vapor condenses due to the temperature difference between the interior of the chamber 190 and the object 10. Thereby, dew forms on a surface of the object 10. In such a state, as the TEC module 40 continues the cooling operation, a frozen layer 22 forms on the surface of the object 10.

The frozen layer 22 serves as a coating layer, which protects the surface of the object 10 when the object 10 is processed by the laser beam, and preventing particles undesirably produced during the process from coming into direct contact with the surface of the object 10.

That is, the object 10 held on the chuck 30 is cooled by the TEC module 40, so that the frozen layer 22 is formed on the object 10 to serve as the coating layer. The laser beam, generated by the laser generating means 120, is reflected by the reflecting means 130 to be irradiated onto the object 10. At this time, since the frozen layer 22 is formed on the object 10, the particles produced while processing the object 10 using the laser beam adhere to the frozen layer 22. When the process is completed, the frozen layer 22 is melted to clean the obj ect 10. At this time, the particles adhering to the frozen layer 22 are also eliminated. Thus, the frozen layer is melted into water which contains the particles. By filtering the water, the environmental pollutants, that is, the particles, are removed. Further, in order to shorten the time required to cool the object 10 after loading the object 10 into the chamber 190, the object 10 may be loaded into the chamber 190 after being preliminarily cooled. In this case, after the object 10 is loaded into the chamber 190, moisture present between the object 10 and the chuck 30 may be frozen. Thus, it is preferable that the preliminary cooling temperature be higher than the condensation point. The condensation point is the temperature at which water vapor begins to condense into water. The condensation point varies depending on the surrounding humidity and is proportional to the surrounding humidity. As such, the frozen layer 22 forms on the surface of the object 10 due to the temperature difference between the chamber 190 and the object 10. The frozen layer 22 is utilized as the coating layer. Since the freezing process is a process to develop ice crystals while condensing water vapor, the frozen layer 22 is not transparent. Thus, it is impossible to read information, such as a pattern or an ID, formed on the object 10 under the frozen layer 22. This problem is solved by melting a part of the frozen layer 22 and re-cooling it. For such an operation, the laser processing apparatus 100 of the present invention further includes the deicing means 200.

The deicing means 200 for melting the frozen layer 22 may have either a contact type structure or a non-contact type structure. ^"When the frozen layer 22 is melted by the contact type structure, the deicing means 200 may comprise a metal plate so that the heated metal plate slides over the surface of the frozen layer 22. Meanwhile, when the frozen layer 22 is melted by the non- contact type structure, the deicing means 200 may comprise a heating coil to evenly spray hot air onto the frozen layer 22. The deicing means 200 having the contact type structure is useful when the surface of the frozen layer 22 is flat. Qn the other hand, the deicing means 200 having the non- contact type structure is useful both when the surface of the frozen layer 22 is flat and when the surface is an uneven surface.

Further, the thickness of the frozen layer 22 formed on the surface of the object 10 varies depending on the internal humidity of the chamber 190. The humidity varies depending on the temperature. According to the present invention, the sensor 170 is mounted within the chamber 190 to detect the temperature and humidity in the chamber 190, thus regulating the thickness of the frozen layer 22. Since the internal humidity of the chamber 190 is usually low, it is not necessary to be concerned about an increase in thickness of the frozen layer 22 due to excessive humidity. When the internal humidity of the chamber 190 detected by the sensor 170 is lower than a predetermined level, the moisture in the air in the chamber 170 is insufficient, so the sufficiently thick frozen layer 22 is not formed. Thus, in order to solve the problem, the humidifying means 180 is provided to supply moisture to air in the chamber 190.

FIG. 5 is a flow chart illustrating a laser processing method, according to the present invention.

In order to process the object 10, the object 10 is loaded into the chamber 190 and held by the chuck 30. Further, at step SlO, a control parameter is set according to an object to be processed.

For easy parameter setting, menu items are preset and registered according to the kind of object, a processing method (cutting method, grooving method, etc.), and others, and are stored in the storage unit 160. Thereafter, the menu items are called, as necessary.

When the control parameter has been set, the TEC module 40 is driven to cool the object 10. Thereby, the frozen layer 22 forms on the surface of the object 10, at step S20. The object 10 may be cooled by the TEC module 40 after being loaded into the chamber 190. However, in order to reduce a cooling time, the object 10 may be loaded into the chamber 190 after being preliminarily cooled. Ih the case of preliminarily cooling the object 10, it is preferable that the preliminary cooling temperature be higher than the condensation point to prevent moisture present between the object 10 and the chuck 30 from freezing.

Further, since the frozen layer 22 formed on the surface of the object 10 is opaque, it is difficult to observe the surface of the object 10. Thus, in order to obtain a transparent frozen layer 22, a part of the frozen layer 22 is melted by the deicing means 200 and then re-cooled. When melting the frozen layer 22, the frozen layer 22 may be molten by the contact type structure, which slides the heated metal plate over the surface of the frozen layer 22, or by the non-contact type structure, which evenly sprays hot air onto the surface of the frozen layer 22.

When the internal humidity of the chamber 190 detected by the sensor 170 is lower than a predetermined level, the humidifying means 180 supplies moisture to air in the chamber 190, to form the sufficiently thick frozen layer 22. Thereafter, the stage conveying means is driven to convey the stage having the object 10 at a predetermined speed, at step S30. At this time, the control unit 110 controls the laser generating means 120, to generate the laser, at step S40. Thus, the laser beam generated by the laser generating means 120 are reflected by the reflecting means 130 to be irradiated onto the object 10, thus processing the object 10. After the object 10 has been processed, the cleaning process is performed at step S50 to remove the frozen layer 22 and the particles produced while the object 10 is processed. The cleaning process may be a wet process or a dry process. The wet cleaning process removes the frozen layer 22 and the particles adhering to the surface of the frozen layer 22, using water. Conversely, the dry cleaning process sprays a gas (hot air) onto the surface of the frozen layer 22 to remove the particles from the surface of the frozen layer 22 while melting the frozen layer 22. Through the cleaning process, the frozen layer is melted into water. The water contains the particles therein. The particles may be eliminated by the filter, thus preventing industrial waste water from being generated.

When the object has been processed and cleaned, the object 10 is unloaded from the chamber 190, and subsequent processes will be carried out.

FIGS. 6A to 6D are views illustrating an example of processing the object by the laser processing method, according to the present invention.

As shown in FIG. 6A, the object 10 held on the chuck 30 is cooled by the TEC module 40 which is provided under the chuck 30, thus forming the frozen layer 22. As shown in FIG. 6B, a laser beam is irradiated onto a predetermined position of the obj ect 10.

When the object 10 has been processed through the laser irradiation, as shown in FIG. 6C, by-products produced in the processing of the object 10, namely, particles B adhere to the surface of the frozen layer 22. Another frozen layer 24 is formed also on a processed portion A. In a detailed description, the object 10 maintains a cooled state even when the laser beam is irradiated, so that the frozen layer 24 is formed on the processed portion A due to the temperature difference between the object 10 and the chamber 190.

After the process has been completed, the object 10 is cleaned through the dry cleaning process or the wet cleaning process to remove the frozen layer 22 and the particles B. Thus, as shown in FIG. 6D, the object 10 having a desired processed portion A is obtained. It is understood by those skilled in the art that the present invention may be embodied in several forms without departing from the spirit and the essential characteristics of the invention. Therefore, the present embodiment is illustrative and not restrictive, since the scope of the invention is denned by the appended claims rather than by the description preceding them, and all changes that fall within meanings and bounds of the claims, or equivalence of such meanings and bounds are therefore intended to be embraced by the claims.

Industrial Applicability

As described above, the present invention provides a laser processing apparatus and method, which enables an object, such a wafer, to be processed by a laser without the necessity of using an expensive coating solution, thus reducing costs required to treat a cleaning solution laden with particles, after the process has been completed, as well as reducing costs for coating solution.

Further, the present invention simplifies an operation of processing an object using a laser, and allows particles generated in the processing of the object using the laser to be easily eliminated by a cleaning process, thus preventing environmental pollution.

Claims

1. A laser processing apparatus to process an object using a laser, the laser processing apparatus comprising: a chuck to hold the obj ect loaded into a chamber; a thermoelectric cooling module provided on a lower surface of the chuck to cool the object via the chuck, thus forming a frozen layer on a surface of the object; insulation means provided on a lower surface of the thermoelectric cooling module; laser generating means to generate and output a laser beam having a predetermined caliber; and reflecting means to reflect the laser beam, generated by the laser generating means, onto the object.

2. The laser processing apparatus according to claim 1 , further comprising: a sensor to detect temperature and humidity in the chamber.

3. The laser processing apparatus according to claim 2, further comprising: humidifying means to supply water vapor to air in the chamber, when the sensor detects that the humidity in the chamber is lower than a predetermined level.

4. The laser processing apparatus according to claim 1, further comprising: deicing means to melt part of the frozen layer.

5. The laser processing apparatus according to claim 4, wherein the deicing means comprises a contact type structure or a non-contact type structure.

6. The laser processing apparatus according to claim 5, wherein the deicing means having the contact type structure comprises a metal plate that can be heated, and the deicing means having the non-contact type structure comprises a heating coil that is heated by water vapor fed therein.

7. The laser processing apparatus according to claim 1, wherein the object is preliminarily cooled to a temperature which is higher than a condensation point, prior to being loaded into the chamber.

8. A laser processing method to process an object using a laser, the laser processing method comprising the steps of: loading the object into the chamber after holding the object on a chuck, with a thermoelectric cooling module mounted to a lower surface of the chuck; setting a control parameter, according to a kind of object and a processing method; forming a frozen layer by driving the thermoelectric cooling module to cool the object held on the chuck; conveying the object; irradiating a laser beam onto a predetermined position of a surface of the object; and cleaning the object after the object has been processed.

9. The laser processing method according to claim 8, wherein the object is preliminarily cooled to a temperature which is higher than a condensation point, prior to being loaded into the chamber.

10. The laser processing method according to claim 8, further comprising: melting and re-cooling part of the frozen layer, between the step of forming the frozen layer on the surface of the object and the step of conveying the object.

11. The laser processing method according to claim 10, wherein the frozen layer is melted by a contact type structure or a non-contact type structure.

12. The laser processing method according to claim 11, wherein the contact type structure melts the frozen layer by sliding a metal plate that can be heated over a surface of the frozen layer, and the non-contact type structure melts the frozen layer by spraying heated air onto the surface of the frozen layer.

13. The laser processing method according to claim 8, wherein the step of foπning the frozen layer is executed after supplying water vapor to air in the chamber, when it is detected that humidity in the chamber is lower than a predetermined level.

14. The laser processing method according to claim 8, wherein the step of cleaning the obj ect is executed by a wet or dry process.