JP2003124116A - Laser crystallization method, method of manufacturing semiconductor device, method of manufacturing liquid crystal display device, and method of manufacturing electroluminescence display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out laser crystallization, conforming to the forming position of a TFT so as to improve the channel region of the TFT in crystallinity and the TFT in performance. SOLUTION: A manufacturing method comprises a first process of forming a metal film pattern 12 on a substrate 11 and sequentially forming an insulating film 13 and a semiconductor film (non-single crystal film) 14 on the substrate 11 so as to cover the metal film pattern 12, a second process of irradiating a prescribed spot on the semiconductor film 14 with a laser beam 21 having an irradiation region formed into a prescribed shape to crystallize the irradiated region as the metal film pattern 12 is used as an alignment mark, and a third process of irradiating a spot slightly off the above spot with a laser beam 22 having an irradiation region formed into a prescribed shape so as to make its irradiated region overlap partially with the former region irradiated with the laser beam 21 and to crystallize the irradiated region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser crystallization method, a semiconductor device manufacturing method, and a liquid crystal display device manufacturing method, and more specifically, a laser crystallization method and a semiconductor device manufacturing method for obtaining crystals with excellent crystallinity. The present invention relates to a method for manufacturing a liquid crystal display device and a method for manufacturing an electroluminescence display device.

[0002]

2. Description of the Related Art An outline of a laser crystallization process that is currently performed will be described with reference to a perspective view of FIG. As shown in FIG. 4, in the conventional laser crystallization, a non-single-crystal film 211 is produced by using a band-shaped beam excimer laser light 221 having a beam cross section of, for example, 200 mm × 0.4 mm by using an optical system 223.
It is performed by repeatedly irradiating a predetermined area 213 of the above. According to this method, the non-single-crystal film 211 on the glass substrate 201 can be replaced with a polycrystalline film in a relatively short time.

However, since the film thickness of the non-single crystal film 211 irradiated with the excimer laser light 221 and the condition range of the energy of the excimer laser light 221 are narrow, accurate laser energy control is required. Various techniques are being developed for the purpose of improving the technique. Among them, a promising method is Reprinted from Materials ResearchSoc.
iety MRS Bullentin, Vol.XXI [3] (1996-3) (USA) p.3
9-48, Materials Research Society Symp. Proc. Vol.6
21 (2000) (USA) Q9.7.1-Q9.7.6, Appl. Phys. Lett. 6
9 [19] (1996-11-4) (USA) p.2864-p.2866, Materials
Research Society Symp. Proc. Vol.452 (1997) (USA)
p.953-p.958, Appl. Phys. Lett. 70 [25] (1997-6-23)
(USA) p.3434-p.3436, IEEE ELECTRON DEVICE LETTERS
VOL.19 NO.8 (1998-8) (USA) p.306-p.308, Appl. Phy
s. A67 (1998) (USA) p.273-p.276, phys.stat.sol.
(a) 166 (1998) (USA) p.603-p.617, etc., the so-called SLS (Sequential Lateral Solidific)
ation).

Whereas conventional crystallization is random nucleus growth, SLS is superior in that it uses lateral method crystal growth.

The conventional crystallization method utilizing random nucleus growth occurs spontaneously in the process of irradiating a laser beam having a relatively large beam cross-sectional area, melting the irradiated film once, and then cooling. It grows around the nucleus. For this reason, it is indispensable to control the location and density of the crystal nuclei, but it is possible to obtain a crystal that is almost the same stochastically, so that a thin film transistor (TFT: Thin Film Tr
The performance of the ansistor is moderate (for example, the electron mobility of the TFT is about 100 cm / V · s). However, there is a drawback that the electron mobility also varies when the energy of the laser light varies.

On the other hand, in SLS, a melted portion and a non-melted portion can be formed adjacent to each other by narrowing the irradiation area of laser light and sharpening the spatial energy density distribution. it can. Therefore, when the melted portion cools and solidifies, crystal growth starts from the adjacent unmelted portion. That is, crystals grow laterally. This results in a constant crystal rather than random nucleus growth. According to this crystallization method,
Even if the laser energy varies, there is almost no influence on crystallization. In addition, if the crystal growth direction and the TFT channel direction are aligned, a high mobility of 300 or more can be obtained.

[0007]

However, the above S
In the crystallization method by LS, it is difficult to match the position of the crystal with the position of the TFT because the irradiation pattern of the laser light when growing the crystal is irrelevant to the position of the TFT formed thereafter. Has the problem.

[0008]

The present invention is a method for laser crystallization, a method for manufacturing a semiconductor device, a method for manufacturing a liquid crystal display device, and a method for manufacturing an electroluminescent display device, which have been made to solve the above problems.

The laser crystallization method of the present invention comprises the steps of forming a metal film pattern on a substrate, then sequentially forming an insulating film and a non-single-crystal film on the substrate to cover the metal film pattern, and the metal film. Using the pattern as an alignment mark, irradiating a predetermined position of the non-single-crystal film with a laser beam having an irradiation region formed in a predetermined shape, crystallizing the irradiation region, and the irradiation region A step of irradiating a laser beam having an irradiation area formed in a predetermined shape at a position shifted from the irradiation area so as to overlap a part thereof and crystallizing the irradiation area is provided.

In the above laser crystallization method, since the metal film pattern used as the alignment mark is formed,
Positioning becomes possible. Then, using the metal film pattern as an alignment mark, a laser beam having an irradiation region formed in a predetermined shape is irradiated to a predetermined position of the non-single-crystal film, and the irradiation region is crystallized. T
It becomes possible to form the crystallization region in accordance with the channel formation region of FT (Thin Film Transistor). That is, it becomes possible to crystallize the region to be crystallized so as to surely obtain good crystallinity.

Further, a laser beam having an irradiation region formed in a predetermined shape is irradiated to a position shifted from the irradiation region so as to overlap a part of the irradiation region crystallized previously, and the irradiation region is crystallized. Therefore, the characteristic of lateral growth is that the region melted by laser light irradiation starts crystal growth from the adjacent unmelted region, which makes it possible to make the center of the crystallization region a region with good crystallinity. Become.

The method of manufacturing a semiconductor device according to the present invention comprises the steps of forming a metal film pattern on a substrate, then sequentially forming an insulating film covering the metal film pattern and a non-single-crystal film on the substrate, Using the film pattern as an alignment mark, a laser beam having an irradiation region shaped in a predetermined shape is irradiated to a predetermined position of the non-single crystal film, and the irradiation region is crystallized, and the irradiation region At least a channel formation region of a transistor is crystallized by irradiating a laser beam having an irradiation region formed in a predetermined shape at a position shifted from the irradiation region so as to overlap a part and crystallizing the irradiation region. And the process.

Since the laser crystallization method of the present invention is used in the above-described semiconductor device manufacturing method, the crystallization region can be formed in accordance with the channel formation region of the transistor. Therefore, a transistor having high mobility can be formed.

The method of manufacturing a liquid crystal display device according to the present invention comprises the steps of forming a metal film pattern on a substrate, then sequentially forming an insulating film covering the metal film pattern and a non-single crystal film on the substrate, Using the metal film pattern as an alignment mark, irradiating a predetermined position of the non-single crystal film with laser light having an irradiation region formed in a predetermined shape, and crystallizing the irradiation region, and the irradiation region. At least a channel formation region of a transistor is crystallized by irradiating a laser beam having an irradiation region formed in a predetermined shape at a position shifted from the irradiation region so as to overlap a part of the, and crystallizing the irradiation region. The driving transistor of the liquid crystal display device is formed in the channel formation region formed by the step of.

Since the laser crystallization method of the present invention is used in the method of manufacturing a liquid crystal display device, it is possible to form the crystallization region in accordance with the channel formation region of the drive transistor of the liquid crystal display device. . Therefore, it becomes possible to form a drive transistor having high mobility.

A method of manufacturing an electroluminescent display device according to the present invention comprises the steps of forming a metal film pattern on a substrate and then sequentially forming an insulating film covering the metal film pattern and a non-single-crystal film on the substrate. Using the metal film pattern as an alignment mark, irradiating a predetermined position of the non-single-crystal film with laser light having an irradiation region formed in a predetermined shape, and crystallizing the irradiation region, and the irradiation. By irradiating a laser beam having an irradiation region formed in a predetermined shape at a position shifted from the irradiation region so as to overlap a part of the region and crystallizing the irradiation region, at least the channel formation region of the transistor is crystallized. The drive transistor of the electroluminescent display device is formed in the channel formation region formed by the step of forming the electroluminescent display device.

Since the laser crystallization method of the present invention is used in the manufacturing method of the electroluminescence display device, it is possible to form the crystallization region in accordance with the channel formation region of the drive transistor of the electroluminescence display device. become. Therefore, it becomes possible to form a drive transistor having high mobility.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a laser crystallization method of the present invention will be described with reference to the schematic sectional view of FIG.

As shown in FIG. 1A, a metal film is formed on a substrate (for example, a glass substrate) 11 by, for example, sputtering. A so-called refractory metal such as molybdenum (Mo), chromium (Cr), or tungsten (W) is used for this metal film. This is to prevent the metal film from melting when irradiated with laser light. Next, the metal film is patterned to form a metal film pattern 12. There are two ways to use the metal film pattern 12. The first method is to use the metal film pattern 12 as a positioning mark and a gate wiring,
The second method is a case where the metal film pattern 12 is used only as a positioning mark. The first method is used for a bottom gate structure TFT, and the second method is used for a top gate structure TFT.

Here, the case of the bottom gate structure will be described. The side wall of the metal film pattern 12 is formed in a so-called tapered shape having an angle α described later.

A gate insulating film 13 for covering the metal film pattern 12 is grown on the substrate 11 by, for example, silicon oxide by a chemical vapor deposition (hereinafter, CVD is an abbreviation for Chemical Vapor Deposition) method. Form. Further, a semiconductor film 14 made of a non-single crystal film, for example, amorphous silicon having a thickness of 40 nm is formed on the gate insulating film 13.
It is formed by growing to a thickness of -50 nm. It is preferable to continuously form these films.

After that, as shown in FIG. 1B, laser light irradiation is performed. As the laser light, for example, XeCl excimer laser light with a wavelength of 308 nm is used. First, the first irradiation of the laser light 21 is performed on a predetermined region of the semiconductor film 14. The irradiation uses the laser light 21 in the future TFT.
Irradiation is performed by controlling the position from about half the position of the channel that becomes the channel to the outside (a region that will become the source or drain of the TFT in the future). By irradiating the laser beam 21 with position control in this manner, the irradiated region is once melted and then crystallized in the lateral direction when solidified.

Next, as shown in FIG. 1C, the second irradiation of the laser beam 22 is mainly applied to a predetermined region of the semiconductor film 14 which is not first irradiated. At this time, the second irradiation is an area where an excellent crystal is desired and the first irradiation area 1
Irradiation is performed so as to overlap with 41. This overlap is important. The overlapping width is 0.1 μm or more and 3 μm or less, and preferably 0.1 μm or more and 1.0 μm or less. By defining the range of overlap width in this way,
As shown in (4) of FIG. 1, the semiconductor film 14 is crystallized,
The most important channel portion (semiconductor film 14 on the metal film pattern 12) of the TFT undergoes lateral crystal growth, and a crystal in which the crystal is aligned in the channel direction is obtained. On the other hand, a random crystal growth region R is formed in a part of the semiconductor film 14 that is off the metal film pattern 12, but is out of the region that requires good crystallinity.

As shown in FIG. 2A, the metal film pattern 12 is formed by the crystallization method described with reference to FIG.
Is used as the alignment mark and the first laser light irradiation area 1
The semiconductor film 14 made of amorphous silicon is crystallized by performing laser light irradiation twice so that the overlapping portion 143 between the laser light irradiation region 142 and the second laser light irradiation region 142 is on the metal film pattern 12. As described above, when the laser light is irradiated, the semiconductor film 14 on the metal film pattern 12 becomes a film having a good crystal in which the crystal grains grown in the lateral direction are aligned, and the random growth is performed on both sides of the metal film pattern 12. Region R occurs. By irradiating the laser beam so that the random growth region R is deviated from above the metal film pattern 12, the metal film pattern 12 is used as the gate electrode of the TFT and the semiconductor film 14 above it is used as the channel region. By doing so, a TFT with high mobility can be formed.

Next, as shown in (2) of FIG. 2, a resist mask (not shown) for performing source / drain ion implantation is formed by resist coating and a lithographic technique, and then the source mask is used by using the mask. Drain ion implantation is performed to form source / drain regions 15 and 16. By forming the source / drain regions 15 and 16 in this manner, the gate electrode (metal film pattern 1
2) A semiconductor region having an upper crystal grown laterally can be used as a channel region. Note that the lines showing the crystal grains in FIG. 2 are practically invisible.

As described above, when forming the top gate structure during crystallization, if the metal film pattern 12 is used as an alignment mark for alignment, a TFT will be formed in the future. It can be shared with the alignment mark used when going out. Therefore, the irradiation area of the laser light and the formation area of the TFT can be matched. On the other hand, in the case of the bottom gate structure, since the metal film pattern 12 can be used for the gate wiring, the manufacturing process can be shortened.

Here, an example of a crystallization process in manufacturing a TFT will be described in detail below with reference to FIG.

For example, by sputtering, for example, 3
A metal film made of molybdenum is formed on a substrate (glass substrate) 11 of 00 mm × 350 mm. In the above sputtering, 100% argon was used as the gas and the substrate temperature was set to 90%.
The film was formed at a temperature of 90 ° C. and a thickness of 90 nm.

Next, a resist pattern is formed by ordinary resist coating and lithographic techniques. In addition,
Since the side wall of this resist pattern has a tapered shape, baking is performed, for example, at about 140 ° C. to leave the side wall of the resist pattern blunt. After that, etching is performed using this resist pattern as a mask to process the metal film to form a metal film pattern 12. In this etching, for example, a reactive ion etching apparatus is used, sulfur hexafluoride (SF ₆ ), oxygen (O ₂ ), and helium (He) are used as etching gas, the substrate temperature is set to 60 ° C., and 1185 W is used. Etching was performed with the power of.

After that, the resist pattern is removed. Thus, the taper angle α of the side wall of the metal film pattern 12 is 5 ° to 30 °, preferably 10 ° to 20 °.
Is formed. Here, the metal film pattern 12
It is important in the subsequent laser crystallization process to control the side wall taper angle of 10 ° to 20 °.

After the gate wiring made of the metal film pattern 12 is formed as described above, the metal film pattern 12 is formed.
A non-single-crystal film (for example, an amorphous silicon film) is formed as a semiconductor film 14 that will form the gate insulating film 13 and the active region in a state of covering the. For example, a plasma CVD method is used to form these films, and as an example,
The substrate heating temperature is set to 420 ° C. First, in forming the silicon nitride film of the gate insulating film 13, monosilane (SiH ₄ ), ammonia (NH ₃ ), and nitrogen (N ₂ ) are used as source gases.
Was used to form a film with a thickness of 50 nm. When the silicon oxide film is continuously formed, monosilane (SiH
₄ ) and dinitrogen monoxide (N ₂ O) were used to form a film having a thickness of 120 nm. Subsequently, an amorphous silicon film is formed. In forming the amorphous silicon film, 100% monosilane (SiH ₄ ) was used as a source gas, and
The film was formed to a thickness of nm.

After that, a laser crystallization device (for example, Xe
Cl laser crystallizer, wavelength: 308 nm, pulse width:
30 ns) is used to perform the laser crystallization method of the present invention.

According to the present invention, because of lateral growth,
Energy higher than 320 mJ / cm ² , eg 38
Laser light irradiation was performed at 0 J / cm ² , and similar crystal growth was obtained on both the substrate 11 and the metal film pattern 12. Moreover, the number of irradiations was twice, which was far less than the conventional 20 times.

In the conventional laser crystallization method, 95
% Overlap, 300 mJ / cm ² ~ on the substrate
Crystallization was performed by irradiation with energy of 320 mJ / cm ² . It is necessary to perform crystallization at a low energy density because random growth occurs when the energy density of the irradiation laser beam reaches 380 J / cm ² .

In an actual liquid crystal drive circuit or electroluminescence drive circuit on a glass substrate, a large number of TFTs are arranged side by side. The crystallization method in such a case is
This will be described with reference to the layout diagram of FIG.

As shown in FIG. 3A, in a structure in which a large number of transistors having different sizes are lined up, the mask of the pattern of laser light irradiation in which the openings 42 and 43 are aligned with the arrangement of the transistor formation regions 31 and 32 is used. 41 is formed, the mask 41 is aligned with the positions of the transistor formation regions 31 and 32, and the first irradiation is performed. Then, as shown in FIG. 3B, the mask 41 is shifted to the right in the drawing. Then, the second irradiation may be performed so that the openings 42 and 43 partially overlap the first irradiation areas (areas indicated by the chain double-dashed lines) 51 and 52, respectively. Note that the transistors may all have different sizes.

According to the crystallization method of the present invention, it is possible to crystallize only the region desired to be crystallized, for example, only the region desired to have high mobility, regardless of the number of transistors. The other regions may be crystallized by using a conventional crystallization method, or may not be crystallized when crystallization is not necessary.

According to the above crystallization method, since it is possible to recognize the region where the transistor is formed and to irradiate only the region where the transistor is formed with the laser beam to crystallize the region, the region is crystallized. Areas that are not needed need not be crystallized. Therefore, the throughput can be improved, and the waste of energy can be reduced, so that energy can be saved.

[0039]

As described above, according to the laser crystallization method of the present invention, a laser beam having an irradiation region formed into a predetermined shape is irradiated with a non-single crystal by using a metal film pattern as an alignment mark. By irradiating a predetermined position on the film and crystallizing the irradiated area, for example, a TFT (Thin Fil
It is possible to form the crystallization region in accordance with the channel formation region of the m Transistor). That is, it becomes possible to crystallize the region to be crystallized so as to surely obtain good crystallinity. Further, since the irradiation area can be limited, the irradiation area can be reduced, and throughput can be improved and energy can be saved.

According to the method of manufacturing a semiconductor device of the present invention,
Since the laser crystallization method of the present invention is used, the crystallization region can be formed in accordance with the channel formation region of the transistor. Therefore, high mobility,
It becomes possible to form a transistor having a small Vth. In addition, it becomes possible to form transistors having different mobilities desired in the design on the same substrate. Furthermore, when forming a bottom gate structure transistor,
Crystallization can be performed without increasing the number of steps.

According to the method of manufacturing a liquid crystal display device of the present invention, since the laser crystallization method of the present invention is used,
It becomes possible to form the crystallization region in accordance with the channel formation region of the driving transistor of the liquid crystal display device. Therefore, it becomes possible to form a driving transistor having high mobility and small Vth.

According to the manufacturing method of the electroluminescence display device of the present invention, since the laser crystallization method of the present invention is used, the crystallization region is formed in accordance with the channel formation region of the drive transistor of the electroluminescence display device. It becomes possible to do. Therefore, it becomes possible to form a driving transistor having high mobility and small Vth.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a laser crystallization method of the present invention.

FIG. 2 is a layout diagram illustrating a method of forming a source / drain of a TFT by the crystallization method of the present invention.

FIG. 3 is a layout diagram showing a crystallization method of the present invention when a large number of TFTs are arranged side by side.

FIG. 4 is a perspective view showing an outline of a conventional laser crystallization process.

[Explanation of symbols]

11 ... Substrate, 12 ... Metal film pattern, 14 ... Semiconductor film (non-single crystal film) 21, 22 ... Laser light

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01S 3/00 F term (reference) 2H088 FA16 HA08 2H092 JA28 JA37 MA30 5F052 BA02 BA12 BB07 DA01 DA02 DB03 EA13 JA02 5F072 AA06 JJ08 JJ20 RR05 SS06 YY08 5F110 AA30 BB01 CC02 CC08 DD02 EE04 EE23 FF02 FF29 GG02 GG13 GG25 GG44 HJ13 PP03 PP04 PP05 PP06 PP23 PP40 QQ09

Claims (8)

[Claims] 1. After forming a metal film pattern on a substrate,
A step of sequentially forming an insulating film covering the metal film pattern and a non-single-crystal film on the substrate, and using the metal film pattern as an alignment mark,
Laser light having an irradiation region shaped into a predetermined shape is irradiated to a predetermined position of the non-single-crystal film, and the irradiation region is crystallized, and the irradiation region is overlapped with a part of the irradiation region. A laser crystallization method comprising: irradiating the shifted position with a laser beam having an irradiation region formed in a predetermined shape, and crystallizing the irradiation region. 2. The laser crystallization method according to claim 1, wherein the irradiation region formed in the predetermined shape is formed by an optical system using a mask. 3. After forming a metal film pattern on the substrate,
A step of sequentially forming an insulating film covering the metal film pattern and a non-single-crystal film on the substrate; and using the metal film pattern as an alignment mark, a laser beam having an irradiation region formed in a predetermined shape, Irradiating a predetermined position of the non-single-crystal film and crystallizing the irradiation region, and having an irradiation region formed in a predetermined shape at a position displaced from the irradiation region so as to overlap a part of the irradiation region. A method of manufacturing a semiconductor device, comprising the steps of irradiating a laser beam and crystallizing an irradiation region thereof to crystallize at least a channel formation region of a transistor. 4. The method of manufacturing a semiconductor device according to claim 3, wherein the irradiation region formed in the predetermined shape is formed by an optical system using a mask. 5. The method of manufacturing a semiconductor device according to claim 4, wherein the mask is formed according to the arrangement of the transistors. 6. The method of manufacturing a semiconductor device according to claim 3, wherein the metal film pattern is used for a gate electrode of the transistor. 7. After forming a metal film pattern on the substrate,
A step of sequentially forming an insulating film covering the metal film pattern and a non-single-crystal film on the substrate; and using the metal film pattern as an alignment mark, a laser beam having an irradiation region formed in a predetermined shape, Irradiating a predetermined position of the non-single-crystal film and crystallizing the irradiation region, and having an irradiation region formed in a predetermined shape at a position displaced from the irradiation region so as to overlap a part of the irradiation region. Characterized in that a driving transistor of a liquid crystal display device is formed in a channel formation region formed at least by irradiating a laser beam and crystallizing the irradiation region to crystallize the channel formation region of the transistor. Liquid crystal display device manufacturing method. 8. After forming a metal film pattern on the substrate,
A step of sequentially forming an insulating film covering the metal film pattern and a non-single-crystal film on the substrate; and using the metal film pattern as an alignment mark, a laser beam having an irradiation region formed in a predetermined shape, Irradiating a predetermined position of the non-single-crystal film and crystallizing the irradiation region, and having an irradiation region formed in a predetermined shape at a position displaced from the irradiation region so as to overlap a part of the irradiation region. Characterized by forming a drive transistor of an electroluminescent display device in a channel formation region formed by at least a step of crystallizing a channel formation region of a transistor by irradiating laser light and crystallizing the irradiation region. Method of manufacturing electroluminescent display device.