KR102182301B1 - Heating apparatus for heating target material using laser beam and method of indirect heating using laser beam - Google Patents

Abstract

A heating device that heats a target material using a laser beam includes a stage on which the target material is placed, a laser module that generates and outputs a laser beam, and a plurality of units that are rotated around a rotation axis and reflect the laser beam to enter the target material. It includes a polygon mirror having a reflective surface of. The target material includes a first material containing a metal and a second material containing an inorganic material disposed adjacent to the first material, and the first material is directly heated by irradiating the laser beam to the first material. The second material adjacent to the first material is heated indirectly.

Description

A heating device that heats a target material using a laser beam and an indirect heating method using a laser {HEATING APPARATUS FOR HEATING TARGET MATERIAL USING LASER BEAM AND METHOD OF INDIRECT HEATING USING LASER BEAM}

The present invention relates to a heating apparatus for heating a target material using a laser beam and an indirect heating method using a laser.

By irradiating the target material with a laser, the target material can be heat treated. 1 is a view showing a heating device for heating a target material using a conventional laser beam, Figure 2 is a view showing a laser beam formed through the conventional heating device.

Referring to FIGS. 1 and 2, a conventional heating device may include a laser module 100, an optic 110, a reflective mirror 120, and a stage 130 for placing the target material 140. .

The laser output from the laser module 100 passes through the optics 110 and is formed into a rod-shaped beam 200. In this case, in the rod-shaped beam 200, the long direction is referred to as a beam length, and the short direction is referred to as a beam width.

On the other hand, when the target material 140 is exposed to the laser for a long time, the grain size of the specific phase of the target material 140 increases, and accordingly, the resistance decreases, thereby increasing the leakage current. Due to this characteristic, there is a problem in that it is difficult to use for industrial applications requiring large resistance.

In this regard, the exposure time (Dwell Time) of the target material 140 is defined as in Equation 1 (Dwell time formula).

Dwell Time (DT) = BW/V _Stage (Equation 1)

In a method of heating a target material using a conventional heating apparatus, there are a method of reducing the beam width and a method of increasing the speed of the stage 130 in order to reduce the exposure time.

However, in general, it is difficult to control the minimum line width of the laser to be less than 70 to 80 um even when using sophisticated optics, and it is difficult to increase the speed of the stage 130 to a certain level or more. Due to the weight of the stage 130, there is a limit to increasing the speed of the motor by 0.5m/s or more in terms of the performance of the currently used motor. Increasing the actual take-off time can increase it beyond that, but it is not easy to apply it to the actual process because this also increases the processing time for each scan.

For this reason, according to the conventional heating device, a minimum exposure time of 140us is derived as shown in Equation 2.

70um/(0.5m/s)=140us (Equation 2)

Therefore, the conventional heating device can be used only for a target material requiring a relatively large grain size due to an exposure time of about 140us. That is, when a target material requiring a relatively small grain size is heated by using a conventional heating device, the grain size of the target material increases, resulting in a leakage current.

Prior art literature: Patent Publication No. 10-2017-0000385

The present invention aims to solve the above-described problems, and provides a heating device and an indirect heating method to reduce the grain size of the target material by reducing the exposure time and thereby reduce the leakage current in heating a target material using a laser beam. I want to. However, the technical problem to be achieved by the present embodiment is not limited to the technical problems as described above, and other technical problems may exist.

As a technical means for achieving the above technical problem, an embodiment of the present invention is a heating apparatus for heating a target material using a laser beam, a stage on which the target material is placed, and a laser generating and outputting a laser beam A module and a polygon mirror having a plurality of reflective surfaces that are rotated about a rotation axis and reflect the laser beam to be incident on the target material, and the target material is a first material containing a metal and adjacent to the first material. And a second material containing an inorganic material disposed as described above, and the first material is directly heated by irradiating the laser beam onto the first material, thereby indirectly heating the second material adjacent to the first material.

In addition, another embodiment of the present invention has a stage on which a target material is placed, a laser module that generates and outputs a laser beam, and has a plurality of reflective surfaces that are rotated around a rotation axis and reflect the laser beam to enter the target material. In the indirect heating method using a laser performed in a heating device including a polygon mirror, the step of adjacently disposing a first material containing a metal and a second material containing an inorganic material as the target material, and the laser beam It may include the step of indirectly heating the second material adjacent to the first material by irradiating the first material to directly heat the first material.

According to any one of the above-described problem solving means of the present invention, in heating a target material using a laser beam, a heating device and an indirect heating method that reduce the grain size of the target material by reducing the exposure time and thereby reduce leakage current Can provide.

1 is a view showing a heating device for heating a target material using a conventional laser beam.
2 is a diagram showing a laser beam formed through a conventional heating device.
3 is a view showing a heating device according to an embodiment of the present invention.
4 is a diagram illustrating a projective system according to an embodiment of the present invention.
5 is a view showing a beam guide module according to an embodiment of the present invention.
6 is a diagram illustrating that a laser beam is scattered by an interface where two adjacent reflective surfaces meet among a plurality of reflective surfaces.
7 is a flowchart illustrating an indirect heating method using a laser according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and similar reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, when a part is said to be "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element interposed therebetween. . In addition, when a part "includes" a certain component, it means that other components may be further included, and one or more other features, not excluding other components, unless specifically stated to the contrary. It is to be understood that it does not preclude the presence or addition of any number, step, action, component, part, or combination thereof.

In the present specification, the term "unit" includes a unit realized by hardware, a unit realized by software, and a unit realized using both. Further, one unit may be realized using two or more hardware, or two or more units may be realized using one hardware.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view showing a heating device according to an embodiment of the present invention. Referring to FIG. 3, the heating device may include a stage 10, a laser module 20, a polygon mirror 30, an incidence angle control module 40, a beam guide module 50, and a projective system 60. have.

The target material 70 is placed on the stage 10. The target material 70 may include a first material containing a metal and a second material containing an inorganic material disposed adjacent to the first material.

The first material is, for example, titanium (Ti), titanium nitride (TiN), titanium silicide (TiSi), tantalum (Ta), tantalum nitride (TaN), cobalt (Co), cobalt silicide (CoSi), nickel (Ni ), nickel silicide (NiSi), ruthenium (Ru), tungsten (W), tungsten silicide (WSi), copper (Cu), rhenium (Re), molybdenum (Mo), niobium (Nb), chromium (Cr) ) May include any one of.

The second material is, for example, hafnium oxide (HfO ₂ ), hafnium silicon oxide (HfSiO ₄ ), zirconium oxide (ZrO ₂ ), zirconium silicon oxide (ZrSiO ₄ ), lanthanum oxide (La ₂ O ₃ ), lanthanum aluminum Nate (LaAlO ₃ ), aluminum oxide (Al ₂ O ₃ ), tantalum oxide (Ta ₂ O ₅ ), yttrium oxide (Y ₂ O ₃ ), titanium dioxide (TiO ₂ ), strontium titanium (SrTiO ₃ ), ruthenium oxide (RuO ₂ ), strontium ruthenate (SrRuO ₃ ), titanium dioxide (TiO ₂ ), barium titanate (BaTiO ₃ ) may contain any one of.

The stage 10 moves in at least one direction so that the entire target material 70 is scanned by the laser beam.

The laser module 20 generates and outputs a laser beam. The laser module 20 may include, for example, any one of a CO2 laser, a YAG laser, a diode laser, and a fiber laser.

The laser beam may have a wavelength in the range of 1 um to 11 um, preferably 10 um to 11 um, for example.

The laser beam can be irradiated to the first material, for example. Accordingly, the second material disposed adjacent to the first material may be indirectly heated.

In general, metals have relatively high free electrons and can be heated to very high temperatures (for example, 2000 to 3000 degrees) by a laser. On the other hand, it is relatively difficult to heat a material containing inorganic materials (eg, SiO ₂ , Si, Si ₃ N ₄ ) through a laser.

The present invention utilizes these properties, after placing a first material containing a metal and a second material containing an inorganic material adjacent to each other (for example, placing them in contact with each other), and then directly irradiating a laser beam to the first material to produce a The second material can be heated effectively by indirect heating the second material.

The polygon mirror 30 rotates about a rotation axis and has a plurality of reflective surfaces that reflect the laser beam.

Due to the rotation of the polygon mirror 30, the laser beam may have a speed of several m/s to several hundred m/s (eg, 2 m/s to 180 m/s). In this case, the exposure time (Dwell Time) may be defined through the beam width and the speed of the laser beam.

That is, in the case of substituting the speed of the laser beam instead of the speed of the stage in Equation 1 (assuming that the beam width is the same), the speed of the laser beam is 2 m/s from several hundred ns to several us (eg, 0.39 us to 35 us). To 180 m/s exposure times are derived.

As described above, according to the heating apparatus of the present invention, it is possible to provide a minimum exposure time of at least 4 times to at most 200 times as compared to a conventional heating apparatus.

Accordingly, the heating apparatus of the present invention can heat a target material requiring a relatively small grain size, and can reduce a leakage current generated as the grain size increases.

The incidence angle control module 40 controls an incidence angle at which the laser beam reflected on the reflective surface of the polygon mirror 30 is incident on the target material 70.

The incident angle control module 40 may control the incident angle incident on the target material 70 based on the Brewster Angle of the target material 70. For example, the incidence angle control module 40 may control the angle at which reflection occurring at the interface between the first material and the second material is minimized according to the difference between the Brewster angles of the first material and the second material.

By freely controlling the incident angle incident on the target material 70 using the incident angle control module 40, not only the use of the Brewster angle applied to a film composed of a specific film quality or a composite film of several films, but also the use of It is possible to provide a means to create an optimal process in a conventional structure used or in a process in which such structures are stacked in several arrangements. For example, the concept of an incidence angle can be applied in various processes by setting an optimal incidence angle even in a trench structure with a depth that must be applied differently from the Brewster angle.

For example, in the case of a capacitor of a DRAM according to an embodiment of the present invention, a capacitor node having a cylindrical shape is formed of metal. At this time, the reference point of the Brewster angle of the incident wave should be the surface of the structure made of several μm, not the surface of Si.

The same reason may be applied to heat treatment of a channel of a vertical NAND flash or a high-k film according to another embodiment.

Separately, for the original purpose of indirect heating by heating metal, if the aspect ratio (A/R) is large in the applied process, the laser beam is heated from the surface of the object that arrives first, and the farther away from the surface, the more It will be heating by thermal conduction, not by direct heating by laser. In this way, heating by thermal conduction may cause a temperature non-uniformity between the upper and lower portions of the target material. To prevent this, in consideration of the aspect ratio (A/R), it may be necessary to use an incidence angle in a range in which the laser power can reach almost simultaneously from the top to the bottom of the structure. At this time, the angle of incidence can be freely adjusted according to the purpose and result.

The projective system 60 is disposed between the polygon mirror 30 and the target material 70. The projective system 60 may optimize the uniformity of the laser beam according to the length of the trajectory of the laser beam. 4 is an enlarged view of the projective system 60.

Referring to FIG. 5 together, the beam guide module 50 is disposed between the polygon mirror 30 and the incidence angle control module 40, and may control an incidence range in which the laser beam is incident on the target material 70.

Referring to FIG. 6 for a moment, a laser beam is scattered by an interface where two adjacent reflective surfaces of a plurality of reflective surfaces of a polygon mirror meet, and the scattered laser beam reaches a specific position of the target material to change the target material. have.

Therefore, it is necessary to prevent the scattered laser beam from reaching the target material.

6 shows a laser beam reflected on a plurality of reflective surfaces of a polygon mirror. In particular, (c) of FIG. 6 shows that the laser beam scattered by the interface where two adjacent reflective surfaces meet among the plurality of reflective surfaces reaches a specific position of the target material.

Returning to FIG. 5 again, the beam guide module 50 includes a plurality of beam dumps 51 and 52 that determine the incidence range of the laser beam apart by a predetermined distance.

The plurality of beam dumps 51 and 52 block the scattered laser beam 53 by an interface where two adjacent reflective surfaces meet among the plurality of reflective surfaces.

Accordingly, it is possible to prevent the laser beam scattered from reaching a specific position of the target material 70 due to an interface where two adjacent reflective surfaces of the plurality of reflective surfaces meet.

The heating device of the present invention can be used in a process of heating a channel film in a vertical NAND (VNAND) structure.

For example, in the vertical NAND structure, forming an insulating layer in a trench embodied in a device structure, and then forming a channel layer made of a second material as the second material structure on the insulating layer in the trench; After forming the channel layer, forming the first material structure as a core made of a first material that fills the remaining empty space in the trench and a laser receiving pad made of a first material to be connected to the core on the upper surface of the device structure Can be. At this time, a reaction or interdiffusion between the first material and the second material may occur due to high-temperature heating, and at least one third material capable of preventing this may be included between the first material and the second material. This is because, when a reaction or interdiffusion occurs, it may not be easy to remove the first material in the subsequent step of removing the first material. The third material is, for example, a SiO ₂ film, Si ₃ N ₄ , It may include one of polysilicon (Polysilicon) and amorphous silicon (Amorphous Si).

Here, in order to lower the resistance of the channel layer, the second material may be heated or melted by irradiating the laser onto the laser receiving pad.

The device structure may include a vertical NAND (VNAND) structure, and the second material may include polysilicon. The insulating layer may include a trap layer 12 made of silicon nitride, a blocking oxide layer made of aluminum oxide, and an HQ oxide layer made of silicon oxide.

With conventional lasers, there was a limit to heating or melting the entire polysilicon (4 to 5 micrometers depth), which is a channel layer of a vertical NAND (VNAND) structure, but a gap fill ( Gap-fill) or macaroni fill, and then annealing using a CO2 laser, YAG laser, diode laser, or fiber laser heats the first material and 2 By heating or melting a channel layer made of polysilicon, which is a material, the resistance is lowered to increase the current of the channel. The gap-fill or macaroni fill of the provided first material is then removed by a suitable method. It is very important to increase the current by reducing the resistance of the channel film as the number of stacks of the vertical NAND (VNAND) structure increases.In this embodiment, after forming the first material structure around the channel film, the CO2 laser , YAG laser, diode laser, fiber (fiber) laser can be implemented through annealing.

Meanwhile, in order to indirectly heat the channel film 19, it is not easy to directly irradiate a CO2 laser, YAG laser, a diode laser, or a fiber laser into a deep portion having a narrow cross-sectional area. It is effective to form a laser receiving pad and irradiate the laser receiving pad with CO2 laser, YAG laser, diode laser, and fiber laser.

In addition, the heating apparatus of the present invention can be used in a process of indirectly heating the dielectric film by heating the upper electrode in a DRAM capacitor structure including a dielectric film made of a second material and an upper electrode made of the first material.

For example, in the DRAM capacitor structure, forming a lower electrode in a trench implemented in a device structure, forming a dielectric film made of a second material as the second material structure on the lower electrode in the trench; And forming an upper electrode made of a first material on the dielectric film in the trench as the first material structure and a laser receiving pad made of a first material to be connected to the upper electrode on the upper surface of the device structure. I can.

Here, in order to increase the dielectric constant of the dielectric layer, the second material may be heated or melted by irradiating the laser onto the laser receiving pad.

The device structure includes a capacitor structure of a DRAM, the first material includes titanium nitride (TiN) or ruthenium (Ru), and the second material is HfO ₂ , HfSiO4, ZrO ₂ , ZrSiO ₄ , La ₂ O ₃ , LaAlO ₃ , Al ₂ O ₃ , Ta ₂ O ₅ , Y ₂ O ₃ , TiO ₂ , may include any one of SrTiO ₃ . In this case, the dielectric layer is sequentially phase-transformed into an amorphous structure, a monoclinic structure, a tetragonal structure, and a cubic structure, whereby a dielectric layer having a sufficiently high dielectric constant can be implemented. In other words, HfO ₂ , HfSiO ₄ , ZrO ₂ , ZrSiO ₄ , La ₂ O ₃ , LaAlO ₃ , Al ₂ O _{3 that} change phase at relatively high temperature using CO2 laser, YAG laser, diode laser, and fiber laser , Ta ₂ O ₅ , Y ₂ O ₃ , TiO ₂ , SrTiO _{3 A} tetragonal phase, an orthoromic phase, or a cubic phase that guarantees high permittivity in any one of Higher dielectric properties can be realized by odor.

In addition, the heating device of the present invention can be used in a process of indirectly heating polysilicon by heating a metal in a transistor structure of a memory device including metal and polysilicon.

For example, the memory device may include forming a gate oxide film as a step of forming a transistor structure of the memory device; Forming a polysilicon layer as the second material structure on the gate oxide layer; A titanium nitride (TiN) film, a tungsten nitride (WN) film, a silicon tungsten (WSi) film, or a tantalum nitride (TaN) film is first formed on the polysilicon film as the first material structure, and then a tungsten (W) film is sequentially formed. It can be formed by the step of. At this time, a reaction or interdiffusion between the first material and the second material may occur due to high-temperature heating, and at least one third material capable of preventing this may be included between the first material and the second material. This is because, when a reaction or interdiffusion occurs, it may not be easy to remove the first material in the subsequent step of removing the first material. The third material is, for example, a SiO ₂ film, Si ₃ N ₄ , It may include one of polysilicon (Polysilicon) and amorphous silicon (Amorphous Si).

Here, in order to lower the equivalent oxide film thickness (EOT) of the transistor, at least a portion of the polysilicon film may be heated or melted by irradiating the laser onto the tungsten film.

That is, the transistor structure of DRAM (or FLASH) is composed of Gate oxide / Polysilicon / Metal (TiN/W). At this time, since the metal is easily heated, local heating or melting of the polysilicon in contact with the metal is induced to enhance the activation of B or P, thereby reducing polysilicon depletion and reducing EOT. I can. In other words, activation of polysilicon depletion at the metal gate to the extent that polysilicon depletion is eliminated for a short time at high temperature by metal assisted heating is possible.

In addition, the heating device of the present invention indirectly heats the second material by directly heating the first material in the transistor structure of the logic element including TiN (or TaN)/W as the first material and the High-k material as the second material. It can be used in the process of doing.

For example, the transistor structure of a logic device may include forming an amorphous polysilicon film as the second material structure; And forming the first material structure on the amorphous polysilicon layer.

Here, by irradiating the laser on the first material structure to heat or melt at least a portion of the amorphous polysilicon layer, the resistance of the second material structure may be lowered.

Among the ways to lower the resistance of polysilicon (or amorphous silicon), there is a poly melt method as an easy way to increase the general grain size. By connecting polysilicon (or amorphous silicon) and metal and using CO2 laser, YAG laser, diode laser, and fiber laser, melting of polysilicon (or amorphous silicon) by heating of metal can be realized.

In addition, the heating device of the present invention coats the metal film under the photoresist during the photolithography process, so that interdiffusion between the exposed and unexposed portions between the photoresist and the photoresist during baking after coating or baking after exposure. ), LER (Line Edge Roughness) or WER (Width Edge Roughness) can be improved. In this case, a reaction or interdiffusion between the photoresist and the metal film may occur due to high temperature heating, and at least one third material capable of preventing this may be included between the first material and the second material. This is because, when reaction or interdiffusion occurs, it may not be easy to remove the photoresist in the subsequent step of removing the photoresist. The third material is, for example, a SiO ₂ film, Si ₃ N ₄ , It may include one of polysilicon (Polysilicon) and amorphous silicon (Amorphous Si).

Besides this, the heating device of the present invention can be applied in various processes.

7 is a flowchart showing an indirect heating method using a laser according to an embodiment of the present invention.

Referring to FIG. 7, in step S900, a first material containing a metal and a second material containing an inorganic material may be disposed adjacent to each other as a target material. In this case, a reaction or interdiffusion between the first material and the second material may occur due to high temperature heating, and at least one third material capable of preventing this may be included between the first material and the second material. The third material is, for example, a SiO ₂ film, Si ₃ N ₄ , It may include one of polysilicon (Polysilicon) and amorphous silicon (Amorphous Si).

In operation S910, the second material adjacent to the first material may be indirectly heated by directly heating the first material by irradiating a laser beam onto the first material.

Although not shown, the indirect heating method using a laser according to an embodiment of the present invention may further include controlling an incidence angle incident on a target material based on a Brewster angle of the target material.

The above description of the present invention is for illustrative purposes only, and those of ordinary skill in the art to which the present invention pertains will be able to understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as being distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

10: stage
20: laser module
30: polygon mirror
40: Incidence angle control module
50: beam guide module
51, 52: beam dump
60: Projective system
70: target substance

Claims (13)

In a heating device for heating a target material using a laser beam,
A stage on which the target material is placed;
A laser module generating and outputting a laser beam;
A polygon mirror having a plurality of reflective surfaces that are rotated about a rotation axis and reflect the laser beam to be incident on the target material; And
A beam guide module for controlling an incidence range in which the laser beam is incident on the target material,
The beam guide module is configured to block a laser beam scattered by an interface where two adjacent reflective surfaces meet among the plurality of reflective surfaces of the polygon mirror, and to pass the laser beam reflected in an area of the reflective surface other than the interface. And
The target material includes a first material containing a metal and a second material containing an inorganic material disposed adjacent to the first material,
The heating device, wherein the laser beam is irradiated to the first material to directly heat the first material to indirectly heat the second material adjacent to the first material.
delete delete The method of claim 1,
Wherein the target material further comprises at least one third material disposed between the first material and the second material.
The method of claim 1,
The target material,
A channel layer formed on the insulating layer in the trench of the device structure and made of the second material;
A core portion formed in the remaining space in the trench and made of the first material; And
The heating device is a vertical NAND (VNAND) connected to the core on the upper surface of the device structure and further comprising a laser receiving pad made of the first material.
The method of claim 1,
The target material,
A dielectric film formed on the lower electrode in the trench of the device structure and made of the second material;
An upper electrode formed on the dielectric layer in the trench and made of the first material; And
The heating device is a DRAM capacitor structure connected to the upper electrode on the upper surface of the device structure and further comprising a laser receiving pad made of the first material.
The method of claim 1,
The target material,
A polysilicon film formed on the gate oxide film and made of the second material;
A metal formed on the polysilicon layer and made of the first material; And
A transistor of a memory device including a third material formed between the polysilicon layer and the metal, and formed of at least one of a SiO ₂ layer, Si ₃ N ₄ , polysilicon and amorphous Si Phosphorus, heating device.
The method of claim 1,
The target material,
TiN or TaN as the first material;
The second material is a transistor structure of a logic device including a high-k material.
A stage on which the target material is placed;
A laser module generating and outputting a laser beam;
A polygon mirror having a plurality of reflective surfaces that are rotated about a rotation axis and reflect the laser beam to be incident on the target material; And
And a beam guide module for controlling an incidence range in which the laser beam is incident on the target material, and the beam guide module is a laser beam scattered by an interface where two adjacent reflection surfaces of the plurality of reflection surfaces of the polygon mirror meet In the indirect heating method using a laser performed in a heating device configured to block and pass the laser beam reflected in the region of the reflective surface other than the interface,
Adjoining a first material containing a metal and a second material containing an inorganic material as the target material; And
Indirectly heating the second material adjacent to the first material by irradiating the laser beam to the first material to directly heat the first material
That includes, indirect heating method using a laser.
The method of claim 9,
The target material includes a High-k material as the second material,
Indirect heating using a laser to indirectly heat the second material adjacent to the first material by forming the second material, forming the first material adjacent to the second material, and then directly heating the first material Heating method.
The method of claim 9,
The target material includes amorphous silicon as the second material,
Indirect heating using a laser to indirectly heat the second material adjacent to the first material by forming the second material, forming the first material adjacent to the second material, and then directly heating the first material Heating method.
delete delete

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