JP2002093709A - Thin-film transistor and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of a thin-film transistor, using laser crystallization. SOLUTION: An island-like semiconductor region on an insulating surface is scanned by a laser beam, having a wavelength of 1,064 nm that is continuously oscillated for crystallizing the island-like semiconductor region, and the crystallized island-like semiconductor region is used to form an active layer. The crystallized island-like semiconductor region is consists of a region that is regarded as a single crystal, thus manufacturing a thin-film transistor with improved electrical characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD [0001] The invention disclosed in the present specification is:
The present invention relates to a method for manufacturing a semiconductor device using a thin film semiconductor having crystallinity and having a gate electrode, for example, a thin film transistor. As an application range of the thin film transistor, an active matrix type liquid crystal display device is known.
In this method, a thin film transistor is arranged as a switching element in each of hundreds of thousands or more of pixels arranged in a matrix to perform fine and high-definition display.

[0002]

2. Description of the Related Art In recent years, attention has been paid to a transistor using a thin film semiconductor formed on a glass or quartz substrate (referred to as a thin film transistor or TFT). This is a technique in which a thin film semiconductor having a thickness of several hundreds to several thousand Å is formed on the surface of a glass substrate or a quartz substrate, and a transistor (insulating gate field effect transistor) is formed using the thin film semiconductor.

As such a thin film transistor, a thin film transistor using an amorphous silicon (amorphous silicon) thin film and a thin film transistor using crystalline silicon have been put to practical use. Thin film transistors using crystalline silicon have excellent properties and are therefore expected to have future potential. In thin film transistors using crystalline silicon semiconductors that are currently in practical use, the crystalline silicon thin film is formed by thermally annealing an amorphous silicon film or directly forming a crystalline silicon film by a vapor deposition method. Is obtained by the method. However, from the viewpoint of lowering the temperature of the process, a photo-annealing method for crystallizing an amorphous silicon film by irradiating strong light such as a laser is promising. (For example, JP-A-4-37144)

When a crystalline semiconductor thin film is obtained by optical annealing, there are roughly two methods. The first method is a method in which etching is performed into a shape of an element for forming a semiconductor thin film and then optical annealing is performed. Another method is a method in which a flat film is optically annealed and then etched into a shape of an element to be formed. In general, it has been known that the former can obtain better characteristics (particularly, field-effect mobility) than the latter. It is presumed that this is because in the former method, as a result of the optical annealing, the film shrinks and stress is applied to the central portion of the pattern.

[0005]

However, a problem still exists in this case. In other words, although the initial characteristics are good, there is a problem that the characteristics rapidly deteriorate as the device is used for a long time.

The cause of the deterioration of the characteristics by the conventional method will be described with reference to FIG. First, an amorphous silicon island-shaped semiconductor region 31 of a rectangle 32 as shown in FIG.
Is formed. When this is optically annealed, the film slightly shrinks due to crystallization (dotted lines in the figure indicate the size of the island-shaped semiconductor region before the optical annealing). In addition, in the shrinking process, a region 33 in which distortion is accumulated is formed on an outer peripheral portion of the island region region. The crystallinity of such a region 33 is not so good. (FIG. 3 (B))

When the gate electrode 34 is formed across such an island region (FIG. 3 (C)), FIG. 3 (D) shows a cross section (ab) along the gate electrode. like,
The region 33 where the strain is accumulated exists under the gate electrode 34 and the gate insulating film 35. When a voltage is applied to the gate electrode, charges are trapped because the interface characteristics between the region 33 and the gate insulating film 35 are not good, and deterioration is caused by a parasitic channel or the like due to the charges. (FIG. 3 (D))

The present invention has been made in view of such deterioration in characteristics, and an object of the present invention is to provide a method of manufacturing an insulated gate semiconductor device with less deterioration.

[0009]

The first aspect of the present invention has the following steps. (1) The width of the narrowest portion of the amorphous semiconductor film is 1
A step of forming an island-shaped semiconductor region by etching to a first shape of not more than 00 μm (2) a step of subjecting the semiconductor region to photo-annealing to crystallize or enhance the crystallinity (3) the semiconductor region Forming a second shape semiconductor region by etching at least 10 μm or more of the end (or peripheral part) of the semiconductor device at which a gate electrode or a channel is to be formed in the semiconductor device.

The second aspect of the present invention includes the following steps. (1) The width of the narrowest portion of the amorphous semiconductor film is 1
A step of forming an island-shaped semiconductor region by etching to a first shape of not more than 00 μm (2) a step of subjecting the semiconductor region to photo-annealing to crystallize or enhance the crystallinity (3) the semiconductor region (4) a step of forming a gate insulating film covering the semiconductor region (5) an etched portion of the end of the semiconductor region (6) N-type or P-type using the gate electrode as a mask
Step of introducing or diffusing type impurities

In the first and second aspects of the present invention, the first shape is any one of a rectangle, a regular polygon, and an oval (including a circle), and more generally, at any point on the outer circumference. Preferably, the shape is not concave.

In the above structure, the amorphous semiconductor film is formed on a substrate having an insulating surface such as a glass substrate or a quartz substrate. The amorphous silicon film is formed by plasma CVD or low pressure heat C.
It is formed by the VD method. For the optical annealing, various excimer lasers such as a KrF excimer laser (wavelength: 248 nm) and a XeCl excimer laser (wavelength: 308 nm), a Nd: YAG laser (wavelength: 1064 nm), the second harmonic (532 nm), and the third Harmonics (wavelength 35
5 nm) or the like. In the present invention, the light source may be a pulse oscillation or a continuous oscillation. Also, JP-A-6-3187
As disclosed in No. 01, metal elements (for example, Fe, Co, N
(i, Pd, Pt, etc.) may be used to promote crystallization.

The invention disclosed in this specification is particularly effective when the island-shaped semiconductor region is formed of a single crystal or a region that can be regarded as a single crystal. As will be described later in detail in Examples, a region which can be regarded as a single crystal or a single crystal is scanned with a laser beam which has been linearly beam-processed with respect to an amorphous silicon film or a crystalline silicon film. It can be obtained by irradiation.

A single crystal or a region that can be regarded as a single crystal is defined as a region satisfying the following conditions. -There is substantially no grain boundary. .One hydrogen or halogen element for neutralizing point defects
It is contained at a concentration of × 10 ¹⁵ to 1 × 10 ²⁰ atoms cm ⁻³ . It contains carbon and nitrogen atoms at a concentration of 1 × 10 ^{16 to} 5 × 10 ¹⁸ atoms cm ⁻³ . It contains oxygen atoms at a concentration of 1 × 10 ^{17 to} 5 × 10 ¹⁹ atoms cm ⁻³ . Note that the concentrations of the above elements were determined by SIMS
(Secondary ion analysis method) Defined as the minimum value of the measurement value.

[0015]

In the invention disclosed in this specification, only the channel portion is etched so as not to be adjacent to the channel which greatly affects the characteristics of the semiconductor device. This is the same as performing etching so that such a region does not remain at a portion where the gate electrode crosses.

FIG. 1 shows the basic configuration of the present invention. First,
As a first shape, a plurality (four in the figure) of island-shaped amorphous semiconductor regions 11 of a rectangle 12 having a long side a and a short side b are formed. In the present invention, the width of the narrowest portion of the first shape is 100 μm
It must be: Above that, the effect of improving characteristics due to shrinkage of the film at the time of light annealing is not recognized. Therefore, b is 100 μm or less.
(Fig. 1 (A))

Next, optical annealing is performed. as a result,
The island-shaped semiconductor region shrinks slightly at the same time as the crystallization (the dotted line in the figure shows the size of the island-shaped semiconductor region before the optical annealing). The periphery of the new island region is indicated by 14. In addition, a region 13 in which distortion due to the contraction process is accumulated is formed around the island-shaped semiconductor region. (FIG. 1B) Thereafter, the outer peripheral portion of the island-shaped semiconductor region 11 is etched to form a semiconductor region 15 for forming a target element (FIG. 1B).
(C)), a gate insulating film (not shown), a gate electrode 16
To form (Fig. 1 (D))

Considering that it is not necessary to remove all the areas where the distortion has accumulated, the method shown in FIG. 2 is also possible.
First, an amorphous semiconductor region 21 having a rectangular shape 22 is formed (FIG. 2A), and when this is optically annealed, the region shrinks as in FIG. 2
3 is formed. (FIG. 2B) Then, the region 24 including the periphery of the portion where the gate electrode is to be formed is etched (FIG. 2C), and a gate insulating film (not shown) is formed to form the gate electrode 26. Since there is no region where strain is accumulated in the channel 25 below the gate electrode, deterioration can be reduced as in the case of FIG. (Figure 2
(D))

In the present invention, the shape (first shape) of the amorphous semiconductor region at the time of the optical annealing is preferably as simple as possible. For example, the shape is a rectangle, a regular polygon, a circle, an ellipse including an ellipse, or the like. For example, as shown in FIG. 4A, when light annealing is performed on a semiconductor region 41 having a shape 42 with a concave portion in the center, when the film is contracted, the central concave portion 4 is formed.
4 is pulled up and down, so cracks and the like are likely to occur in the portion. (FIG. 4 (B))

This is because, as shown in FIG. 4C (arrows indicate the direction of contraction), the contraction of the film occurs around the widest part. Therefore, as the first shape, it is preferable to use a shape that is not constricted and that is convex at all points or not concave at any point.

From such a viewpoint, for example, even if a rectangle as shown in FIG. 1 is employed as the first shape, it is not preferable that the ratio of the long side a to the short side b is too large. In the present invention, it is preferable that a / b ≦ 10.

Further, when the island-shaped semiconductor region is configured as a region that can be regarded as a single crystal or a region that can be substantially regarded as a single crystal, a distortion also occurs at the peripheral portion of the island-shaped semiconductor region during the crystallization. Accumulate.

Since this distortion is also concentrated on the periphery of the island-shaped semiconductor region, the adverse effect of the distortion can be suppressed by removing the periphery of the island-shaped semiconductor region.

[0024]

[Embodiment 1] This embodiment will be described with reference to FIG. FIG. 5 shows a cross-sectional view of two thin film transistors, the left one being a cross section of the thin film transistor cut perpendicular to the gate electrode (perpendicular to ab in FIG. 3),
The one on the right is a cross section cut along the gate electrode (along ab in FIG. 3). The state seen from above may be referred to FIG.

First, a silicon oxide film 502 was formed as a base film on a glass substrate 501 to a thickness of 3000 ° by a sputtering method or a plasma CVD method. Next, plasma C
Amorphous silicon film 503 by VD method or low pressure thermal CVD method
Was formed to a thickness of 500 °. Then, the amorphous silicon film was doped with phosphorus to form N-type impurity regions 504 and 505 to be the source / drain of the thin film transistor.
(FIG. 5 (A))

Next, the amorphous silicon film 503 was etched to form island-like silicon regions 506 and 507. (FIG. 5
(B)) Next, the silicon film was crystallized by irradiating a KrF excimer laser beam. At this time, the regions 504 and 505 into which phosphorus has been introduced are simultaneously crystallized and activated. Laser energy density is 150-500mJ
/ Cm ² was preferred. In addition, laser irradiation process
The irradiation may be performed more than once, and laser beams having different energies may be irradiated.

In this embodiment, first, the energy density 25
Irradiate 2-10 pulses of laser light of 0 mJ / cm ² ,
Next, a laser beam having an energy density of 400 mJ / cm ² was irradiated with 2 to 10 pulses. The substrate temperature during laser irradiation was 200 ° C. The optimum energy density of the laser depends on the substrate temperature and the quality of the amorphous silicon film. As a result, regions 508 in which strain was accumulated were formed at the ends of the island-shaped silicon regions 506 and 507. (FIG. 5 (C))

Next, the edge 509 of the island-shaped silicon region was etched to newly form island-shaped silicon regions 510 and 511. The portion etched in this step is indicated by a dotted line 509 in the figure.
Indicated by (FIG. 5D) Then, a silicon oxide film 512 (gate insulating film) having a thickness of 1200 ° was formed by a plasma CVD method. Also,
On top of that, a 5000-mm-thick aluminum film (0.3%
Scandium (Sc) is deposited by a sputtering method, and this is etched to form gate electrodes 513, 5c.
14 was formed. (FIG. 5E)

Next, a thickness of 50 μm is formed by a plasma CVD method.
A silicon oxide film 515 (interlayer insulator) of 00 ° was deposited, and a contact hole was opened in this. Then, a 5000 mm thick aluminum film is deposited by a sputtering method,
This was etched to form source / drain electrodes / wirings 516, 517. (FIG. 5F) Through the above steps, a thin film transistor was completed. In order to stabilize the characteristics, it is preferable to perform annealing in a hydrogen atmosphere (250 to 350 ° C.) at 1 atm after the contact hole opening step.

Embodiment 2 This embodiment will be described with reference to FIG. Similar to FIG. 5, FIG. 6 shows a cross-sectional view of two thin film transistors. The left one is a cross section of the thin film transistor cut perpendicular to the gate electrode, and the right one is a cross section cut parallel to the gate electrode. It is a cross section. The state seen from above may be referred to FIG.

First, a silicon oxide film 602 was formed as a base film on a glass substrate 601 to a thickness of 3000 ° by a sputtering method or a plasma CVD method. Next, plasma C
Amorphous silicon film 603 by VD method or low pressure thermal CVD method
Was formed to a thickness of 500 °. And on the surface 1 ~
100 ppm nickel acetate (or cobalt acetate)
Was applied to form a nickel acetate (cobalt acetate) layer 604. Since the nickel acetate (cobalt acetate) layer 604 is extremely thin, it does not always have a film shape. (FIG. 6 (A))

Next, this was heated at 350 to 450 ° C. for 2 hours.
Nickel acetate (cobalt acetate) was decomposed by thermal annealing in a nitrogen atmosphere, and nickel (or cobalt) was diffused into the amorphous silicon film 603. Then, the amorphous silicon film 603 was etched to form island-shaped silicon regions 605 and 606. (FIG. 6 (B))

Next, the silicon film was crystallized by light annealing by irradiating a KrF excimer laser beam. In this embodiment, first, the energy density is 200 m
A laser beam of J / cm ² was irradiated with 2 to 10 pulses, and then a laser beam with an energy density of 350 mJ / cm ² was irradiated with 2 to 10 pulses. The substrate temperature during laser irradiation was 200 ° C.

The optimal energy density of the laser depends on the substrate
Nickel added in addition to temperature and film quality of amorphous silicon
It also depends on the concentration of (cobalt). In this embodiment, the secondary
As a result of analysis by ion mass spectrometry (SIMS), 1 ×
10¹⁸~ 5 × 10¹⁸Atom / cm ^ThreeConcentration of nickel (co
(Balt) was confirmed to be contained. like this
Photo-annealing using a catalytic element that promotes crystallization
Regarding the method for performing this, see Japanese Patent Application Laid-Open No. 6-318701.
It is shown. As a result, the island-shaped silicon regions 605 and 606
The region 607 where the strain was accumulated was formed at the end of the.
(FIG. 6 (C))

Next, of the ends 607 of the island-shaped silicon region,
Only the portion traversed by the gate electrode was etched to newly form an island-shaped silicon region. The portion etched in this step is indicated by the dotted line 608 in the figure. (FIG. 6D) Then, a silicon oxide film 609 (gate insulating film) having a thickness of 1200 ° was formed by a plasma CVD method. Also,
A polycrystalline silicon film (containing 1% phosphorus) having a thickness of 5000 ° was deposited thereon by a low pressure CVD method, and this was etched to form gate electrodes 610 and 611. (FIG. 6
(E))

Next, phosphorus ions were introduced into the silicon film by ion doping using the gate electrode as a mask. In this embodiment, phosphine (PH ₃ ) diluted to 5% with hydrogen was used as a doping gas. Acceleration voltage is 60 ~
110 kV was preferred. Dose amount is 1 × 10 ^{14 to} 5
× 10 ¹⁵ atoms / cm ² . Thus, N-type impurity regions (= source / drain) 612 and 613 were formed.

After the doping, the impurities were activated by performing thermal annealing at 450 ° C. for 4 hours. This is because nickel (cobalt) is contained in the semiconductor region. (JP-A-6-26
After the thermal annealing step for activation, optical annealing may be performed by irradiating a laser beam or the like.

After the above steps, a hydrogen atmosphere of 1 atm (2
Annealing at 50 to 350 ° C.) neutralized dangling bonds at the interface between the gate insulating film and the semiconductor region.
(FIG. 6F) Next, a 5000-nm-thick silicon oxide film 616 (interlayer insulator) was deposited by a plasma CVD method, and a contact hole was formed in the silicon oxide film 616. Then, an aluminum film having a thickness of 5000 ° is deposited by a sputtering method, and is etched to form source / drain electrodes / wirings 614 and 61.
5 was formed. (FIG. 6 (G))

[Embodiment 3] In this embodiment, a single crystal is substantially formed by introducing a metal element for promoting crystallization of silicon into an amorphous silicon film and further irradiating a laser beam. An example in which a region which can be regarded as a single crystal is formed, and an active layer of a thin film transistor is formed using the region which can be regarded as a substantially single crystal.

FIG. 7 shows some steps of the thin film transistor shown in this embodiment. First, a silicon oxide film 702 was formed as a base film on a glass substrate 701 to a thickness of 3000 ° by a plasma CVD method or a sputtering method. Next, an amorphous silicon film 703 was formed to a thickness of 500 ° by a plasma CVD method or a low pressure thermal CVD method.

Then, the sample is placed on the spinner 700 together with the substrate. In this state, a nickel acetate solution adjusted to a predetermined nickel concentration was applied to form a water film 704.
This state is shown in FIG. Then, by spin-drying using a spinner, unnecessary nickel acetate solution was blown off, so that a trace amount of nickel element was held in contact with the surface of the amorphous silicon film.

Next, the active layer 705 of the thin film transistor is formed by patterning. In this state, active layer 705 is made of an amorphous silicon film. (FIG. 7 (B))

In this state, laser light was irradiated to crystallize the active layer 705 made of an amorphous silicon film. The laser beam used here is a beam processed linearly. Irradiation with laser light is performed so that the linear laser is irradiated while being scanned from one side of the active layer to the opposite side. Further, it is necessary to use a pulse oscillation excimer laser as the laser light. Here, a KrF excimer laser (wavelength: 248 nm) is used.

The irradiation of the laser beam is performed by heating the substrate to 500 ° C.
This is performed while heating to the temperature described above. This is to alleviate a sudden change in the crystal structure due to laser light irradiation. The heating temperature is preferably in a range from 450 ° C. to a temperature equal to or lower than the strain point of the glass substrate.

When a linear laser beam is irradiated on the amorphous silicon film, the region irradiated with the laser beam is instantaneously melted. Then, by scanning and irradiating the linear laser light, crystal growth gradually proceeds, and a region that can be regarded as a single crystal can be obtained.

That is, as shown in FIG. 7 (C), when linear laser light 708 is irradiated while being gradually scanned from one end of the active layer formed of an amorphous silicon film, 707 is obtained.
The region which can be regarded as a single crystal as shown by the arrow grows with the irradiation of the laser beam, and finally, the entire active layer can be regarded as a single crystal.

Thus, an active layer 709 composed of a silicon thin film which can be regarded as a single crystal was obtained. (FIG. 7
(D))

The region which can be regarded as a single crystal shown here needs to satisfy the following conditions in the region. -There is substantially no grain boundary. .One hydrogen or halogen element for neutralizing point defects
It is contained at a concentration of × 10 ¹⁵ to 1 × 10 ²⁰ atoms cm ⁻³ . It contains carbon and nitrogen atoms at a concentration of 1 × 10 ^{16 to} 5 × 10 ¹⁸ atoms cm ⁻³ . It contains oxygen atoms at a concentration of 1 × 10 ^{17 to} 5 × 10 ¹⁹ atoms cm ⁻³ .

When a metal element that promotes crystallization of silicon is used as shown in the present embodiment, the metal element is contained in the film at 1 × 10 ^{16 to} 5 × 10 ¹⁹ cm ^−3. Must be contained at a concentration of The meaning of this concentration range is that if the concentration range is higher than this, the characteristics as a metal appear and the characteristics as a semiconductor cannot be obtained.If the concentration range is lower than this range, the action of promoting the crystallization of silicon is not achieved. That you can't get it.

As can be seen from the above, the region of the silicon film which can be regarded as a single crystal obtained by the above-described laser light irradiation is essentially different from a general single crystal such as a single crystal wafer. .

During the crystallization due to the laser light irradiation, the film shrinks, and the distortion accumulates toward the periphery of the active layer. That is, distortion concentrates and accumulates on the portion indicated by 710 in FIG. 7D.

In general, the thickness of the active layer is about several hundred to several thousand. The size is several μm square to several hundred μm.
Is the corner. That is, it has a very thin thin film shape. In such a thin film state, FIG.
When the crystal growth progresses as shown in (1), strain concentrates around it, that is, near the growth end point of the crystal growth or in a region where the crystal growth does not progress further.

As described above, mainly due to two causes, strain is concentrated around the active layer.
The presence of such a region in which the strain is concentrated in the active layer is not preferable because it may cause an adverse effect on the operation of the thin film transistor.

Therefore, also in this embodiment, the entire periphery of the active layer is etched. Thus, an active layer 711 including a region substantially regarded as a single crystal as shown in FIG. 7E and having reduced influence of stress can be obtained. (FIG. 7E)

After obtaining the active layer 711, as shown in FIG. 8A, a silicon oxide film was formed as a gate insulating film 712 to a thickness of 1000.degree. Further, a polycrystalline silicon film doped with a large amount of P (phosphorus) is formed to a thickness of 5000 ° by a low pressure thermal CVD method, and is patterned to form a gate electrode 71.
3 was formed. (FIG. 8A)

Next, P (phosphorus) ions were implanted by a plasma doping method or an ion implantation method to form a source region 714 and a drain region 716 in a self-aligned manner.
Then, a region 715 into which impurity ions are not implanted by using the gate electrode 713 as a mask is defined as a channel formation region. (FIG. 8 (B))

Next, a silicon oxide film 717 was formed as an interlayer insulating film to a thickness of 7000 ° by a plasma CVD method using TEOS gas. After the formation of the contact hole, a source electrode and a drain electrode were formed using a laminated film of titanium and aluminum. Although not shown in the drawing, a contact electrode to the gate electrode 713 was formed at the same time. Finally, at 350 ° C. in a hydrogen atmosphere,
By performing heat treatment for a long time, a thin film transistor as shown in FIG. 8C was completed.

In the thin film transistor thus obtained, the active layer is formed of a silicon film that can be regarded as a single crystal, and the electrical characteristics of the thin film transistor are also made of single crystal silicon manufactured using SOI technology or the like. It can be comparable to a thin film transistor using a film.

[Embodiment 4] In this embodiment, the method of irradiating the amorphous silicon film patterned to form the active layer with a laser beam in the structure shown in Embodiment 3 is improved. This is an example that has been devised so that it can be easily performed.

FIG. 9 shows a method of irradiating the active layer with laser light in the process shown in the third embodiment. In this case, a linear laser beam having a longitudinal direction parallel to one side of the patterned amorphous silicon film 901 (which will be referred to as an active layer since it becomes an active layer later) is irradiated. By scanning in the direction of the arrow while irradiating, the active layer 901 is transformed into a region that can be regarded as a single crystal.

The method shown in this embodiment is characterized in that the scanning direction of the linear laser light 900 is set so that the crystal growth proceeds from the corners of the active layer 901 as shown in FIG. I do. When the method of irradiating laser light shown in FIG. 10 is employed, crystal growth proceeds from a narrow region to a wide region gradually as shown in FIG. Then, as compared with the case where laser light is irradiated in the state shown in FIG. 9, a region that can be regarded as a single crystal can be formed more easily, and its reproducibility can be made higher.

[0062]

According to the present invention, deterioration of an insulated gate semiconductor device manufactured using a semiconductor film crystallized by optical annealing can be reduced. Although the description has been given mainly of the silicon semiconductor in the embodiment, the same effect can be obtained in other semiconductors (for example, a silicon germanium alloy semiconductor, a zinc sulfide semiconductor, a silicon carbide semiconductor, and the like). As described above, the present invention has industrial value.

[Brief description of the drawings]

FIG. 1 shows a conceptual diagram (a diagram viewed from above) of a manufacturing process of the present invention.

FIG. 2 shows a conceptual diagram (a diagram viewed from above) of a manufacturing process of the present invention.

FIG. 3 shows a manufacturing process example (a diagram and a cross section viewed from above) of a conventional method.

FIG. 4 shows a force applied to a thin film semiconductor during optical annealing.

FIG. 5 shows a cross-sectional view of a manufacturing process in Example 1.

FIG. 6 shows a cross-sectional view of a manufacturing process in Example 2.

FIG. 7 shows a cross-sectional view of a manufacturing process in Example 2.

FIG. 8 shows a cross-sectional view of a manufacturing process in Example 2.

FIG. 9 is a top view showing a state in which an active layer (a semiconductor region on an island) is irradiated with a linear laser beam.

FIG. 10 is a top view showing a state in which an active layer (a semiconductor region on an island) is irradiated with a linear laser beam.

FIG. 11 shows a state of crystallization following irradiation of a linear laser beam on an active layer (a semiconductor region on an island).

[Explanation of symbols]

REFERENCE SIGNS LIST 11 island-shaped semiconductor region 12 outer periphery of island-shaped semiconductor region before optical annealing 13 region in which strain is accumulated by optical annealing 14 outer periphery of island-shaped semiconductor region after optical annealing 15 semiconductor region for forming semiconductor element 16 gate electrode 21 Island-shaped semiconductor region 22 Outer periphery of island-shaped semiconductor region before optical annealing 23 Region where strain is accumulated by optical annealing 24 Region etched after optical annealing 25 Channel of semiconductor element 26 Gate electrode 31 Island-shaped semiconductor region 32 Island before optical annealing Outer periphery of semiconductor region 33 Region in which strain is accumulated by optical annealing 34 Gate electrode 35 Gate insulating film 41 Island semiconductor region 42 Outer periphery of island semiconductor region before optical annealing 43 Region in which distortion is accumulated by optical annealing 501 Glass substrate 502 Base film (silicon oxide) 503 Amorphous silicon 504, 505 N-type impurity region 506, 507 Island semiconductor region 508 Region where strain is accumulated 509 Etched portion 510, 511 Island semiconductor region 512 Gate insulating film (silicon oxide) 513, 514 Gate electrode (aluminum) 515 interlayer Insulating film (silicon oxide) 516, 517 Source / drain electrode / wiring (aluminum) 601 Glass substrate 602 Underlayer (silicon oxide) 603 Amorphous silicon film 604 Nickel acetate (or cobalt)
Layers 605, 606 Island-shaped semiconductor region 607 Strain-stored region 608 Etched portion 609 Gate insulating film (silicon oxide) 610, 611 Gate electrode (polycrystalline silicon) 612, 613 Source / drain 614, 615 Source / drain electrode -Wiring (aluminum) 614 Interlayer insulator (silicon oxide) 701 Glass substrate 702 Base film (silicon oxide film) 703 Amorphous silicon film 704 Nickel acetate solution water film 705 Active layer (island-shaped semiconductor region) 707 Crystal Region 708 laser light 709 crystallized active layer 710 region with concentrated strain 711 active layer (island-shaped semiconductor region) 712 gate insulating film (silicon oxide film) 713 gate electrode 714 source region 715 channel formation region 716 Drain region 717 Interlayer insulating film (silicon oxide film) 718 source electrode 719 drain electrode 901 active layer (island-shaped semiconductor region) 900 linear laser beam

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[Procedure amendment]

[Submission date] September 5, 2001 (2001.9.5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) HJ01 HJ04 HJ12 HJ13 HJ23 HL03 HL04 HL11 HL23 NN02 NN04 NN23 NN35 PP01 PP03 PP04 PP05 PP23 PP29 PP34 PP38 QQ11 QQ24

Claims (39)

[Claims] 1. An island-shaped semiconductor region on an insulating surface is crystallized by irradiating a continuously oscillated laser beam having a wavelength of 1064 nm while scanning the same to crystallize the island-shaped semiconductor region, and using the crystallized island-shaped semiconductor region. A method for manufacturing a thin film transistor, wherein an active layer is formed by sputtering. 2. An island-like semiconductor region on an insulating surface is irradiated with a continuously oscillated laser beam having a wavelength of 532 nm while scanning, thereby crystallizing the island-like semiconductor region, and using the crystallized island-like semiconductor region. A method for manufacturing a thin film transistor, wherein an active layer is formed by sputtering. 3. An island-shaped semiconductor region on an insulating surface is crystallized by irradiating a continuously oscillated laser beam having a wavelength of 355 nm while scanning the same to crystallize the island-shaped semiconductor region, and using the crystallized island-shaped semiconductor region. A method for manufacturing a thin film transistor, wherein an active layer is formed by sputtering. 4. An island-like semiconductor region on an insulating surface is irradiated with a laser beam having a wavelength of 1064 nm continuously oscillated while scanning, thereby crystallizing the island-like semiconductor region, and using the crystallized island-like semiconductor region. A method of manufacturing a thin film transistor, wherein a scanning direction of the laser light is parallel to one side of the island-shaped semiconductor region. 5. An island-shaped semiconductor region on an insulating surface is crystallized by irradiating a laser beam having a wavelength of 532 nm continuously oscillated while scanning, to crystallize the island-shaped semiconductor region, and using the crystallized island-shaped semiconductor region. A method of manufacturing a thin film transistor, wherein a scanning direction of the laser light is parallel to one side of the island-shaped semiconductor region. 6. An island-shaped semiconductor region on an insulating surface is crystallized by irradiating a continuously oscillated laser beam having a wavelength of 355 nm while scanning the same to crystallize the island-shaped semiconductor region, and using the crystallized island-shaped semiconductor region. A method of manufacturing a thin film transistor, wherein a scanning direction of the laser light is parallel to one side of the island-shaped semiconductor region. 7. An island-shaped semiconductor region on an insulating surface is irradiated with a continuously oscillated laser beam having a wavelength of 1064 nm while scanning to crystallize the island-shaped semiconductor region, and the crystallized island-shaped semiconductor region is used. A method for manufacturing a thin film transistor, wherein a scanning direction of the laser light is oblique to one side of the island-shaped semiconductor region. 8. An island-shaped semiconductor region on an insulating surface is crystallized by irradiating a continuously oscillated laser beam having a wavelength of 532 nm while scanning the same to crystallize the island-shaped semiconductor region, and using the crystallized island-shaped semiconductor region. A method for manufacturing a thin film transistor, wherein a scanning direction of the laser light is oblique to one side of the island-shaped semiconductor region. 9. An island-shaped semiconductor region on an insulating surface is crystallized by irradiating a continuously oscillated laser beam having a wavelength of 355 nm while scanning the same to crystallize the island-shaped semiconductor region. A method for manufacturing a thin film transistor, wherein a scanning direction of the laser light is oblique to one side of the island-shaped semiconductor region. 10. The method for manufacturing a thin film transistor according to claim 1, wherein during the crystallization, crystal growth proceeds as the laser beam is scanned. 11. An island-shaped semiconductor region on an insulating surface is irradiated with a continuously oscillated YAG laser beam while being scanned to crystallize the island-shaped semiconductor region, and active using the crystallized island-shaped semiconductor region. A method for manufacturing a thin film transistor, comprising forming a layer. 12. An island-like semiconductor region on an insulating surface is crystallized by irradiating a second harmonic of a continuously oscillated YAG laser beam while scanning the same to crystallize the island-like semiconductor region. A method for manufacturing a thin film transistor, wherein an active layer is formed using a region. 13. An island-shaped semiconductor region on an insulating surface is crystallized by irradiating continuously irradiated YAG laser light having a wavelength of 532 nm with a wavelength of 532 nm to crystallize the island-shaped semiconductor region. A method for manufacturing a thin film transistor, wherein an active layer is formed using the method. 14. An island-shaped semiconductor region on an insulating surface is crystallized by irradiating a third harmonic of a continuously oscillated YAG laser beam while scanning the same to crystallize the island-shaped semiconductor region. A method for manufacturing a thin film transistor, wherein an active layer is formed using a region. 15. An island-shaped semiconductor region on an insulating surface is irradiated with a continuously oscillated YAG laser beam having a wavelength of 355 nm while being scanned to crystallize the island-shaped semiconductor region. A method for manufacturing a thin film transistor, wherein an active layer is formed using the method. 16. An island-shaped semiconductor region on an insulating surface is irradiated with a continuously oscillated YAG laser beam while scanning the same to crystallize the island-shaped semiconductor region, and is activated using the crystallized island-shaped semiconductor region. A method for manufacturing a thin film transistor for forming a layer, wherein a scanning direction of the YAG laser light is parallel to one side of the island-shaped semiconductor region. 17. The island-like semiconductor region on the insulating surface is crystallized by irradiating the island-like semiconductor region with the second harmonic of a continuously oscillated YAG laser beam while scanning the same, thereby crystallizing the island-like semiconductor region. A method for manufacturing a thin film transistor in which an active layer is formed using a region, wherein a scanning direction of the YAG laser beam is parallel to one side of the island-shaped semiconductor region. 18. The island-shaped semiconductor region on the insulating surface is irradiated with a continuously oscillated YAG laser beam having a wavelength of 532 nm while being scanned to crystallize the island-shaped semiconductor region. A method for manufacturing a thin film transistor, wherein a scanning direction of the YAG laser beam is parallel to one side of the island-shaped semiconductor region. 19. The island-like semiconductor region on the insulating surface is crystallized by irradiating the island-like semiconductor region with the third harmonic of a continuously oscillated YAG laser beam while scanning the same, thereby crystallizing the island-like semiconductor region. A method for manufacturing a thin film transistor in which an active layer is formed using a region, wherein a scanning direction of the YAG laser beam is parallel to one side of the island-shaped semiconductor region. 20. The island-shaped semiconductor region on the insulating surface is irradiated with continuously oscillated YAG laser light having a wavelength of 355 nm while scanning to crystallize the island-shaped semiconductor region. A method for manufacturing a thin film transistor, wherein a scanning direction of the YAG laser beam is parallel to one side of the island-shaped semiconductor region. 21. An island-shaped semiconductor region on an insulating surface is irradiated with a continuously oscillated YAG laser beam while being scanned to crystallize the island-shaped semiconductor region, and active using the crystallized island-shaped semiconductor region. A method for manufacturing a thin film transistor for forming a layer, wherein a scanning direction of the YAG laser beam is oblique to one side of the island-shaped semiconductor region. 22. An island-like semiconductor region on an insulating surface is irradiated with a second harmonic of a continuously oscillated YAG laser beam while scanning the same to crystallize the island-like semiconductor region. A method for manufacturing a thin film transistor in which an active layer is formed using a region, wherein a scanning direction of the YAG laser light is oblique to one side of the island-shaped semiconductor region. 23. The island-shaped semiconductor region on the insulating surface is irradiated with a continuously oscillated YAG laser beam having a wavelength of 532 nm while scanning to crystallize the island-shaped semiconductor region. A method for manufacturing a thin film transistor, wherein an active layer is formed using the YAG laser light, wherein a scanning direction of the YAG laser light is oblique to one side of the island-shaped semiconductor region. 24. The island-like semiconductor region on the insulating surface is irradiated with the third harmonic of a continuously oscillated YAG laser beam while scanning the same to crystallize the island-like semiconductor region, and A method for manufacturing a thin film transistor in which an active layer is formed using a region, wherein a scanning direction of the YAG laser light is oblique to one side of the island-shaped semiconductor region. 25. An island-shaped semiconductor region on an insulating surface is irradiated with a continuously oscillated YAG laser beam having a wavelength of 355 nm while being scanned to crystallize the island-shaped semiconductor region. A method for manufacturing a thin film transistor, wherein an active layer is formed using the YAG laser light, wherein a scanning direction of the YAG laser light is oblique to one side of the island-shaped semiconductor region. 26. The method for manufacturing a thin film transistor according to claim 11, wherein during the crystallization, crystal growth proceeds as the YAG laser beam is scanned. 27. A method for manufacturing a thin film transistor according to claim 11, wherein said YAG laser light is Nd: YAG laser light. 28. The method for manufacturing a thin film transistor according to claim 1, wherein the laser light is a linear laser light. 29. The semiconductor device according to claim 1, wherein the crystallized island-shaped semiconductor region is 1 × 10
^A method for manufacturing a thin film transistor, comprising: carbon and nitrogen at a concentration of ^{16 to} 5 × 10 ¹⁸ atoms / cm ³ ; and oxygen at a concentration of 1 × 10 ^{17 to} 5 × 10 ¹⁹ atoms / cm ³ . 30. The method for manufacturing a thin film transistor according to claim 1, wherein the narrowest portion of the upper surface of the island-shaped semiconductor region is 100 μm or less. 31. The semiconductor device according to claim 1, wherein the upper surface of the island-shaped semiconductor region has a long side a and a short side b.
A ratio of a / b ≦ 10 is satisfied. 32. The method for manufacturing a thin film transistor according to claim 1, wherein an upper surface of the island-shaped semiconductor region is a rectangle, a regular polygon, a circle, or an ellipse. 33. The method for manufacturing a thin film transistor according to claim 1, wherein the island-shaped semiconductor region is an island-shaped amorphous silicon film. 34. The method for manufacturing a thin film transistor according to claim 1, wherein the island-shaped semiconductor region is an island-shaped amorphous silicon-germanium alloy semiconductor film. 35. The method according to claim 1, wherein the crystallized island-shaped semiconductor region is a single crystal region. 36. The method for manufacturing a thin film transistor according to any one of claims 1 to 34, wherein the crystallized island-shaped semiconductor region is a region that can be regarded as a single crystal. 37. A thin film transistor manufactured by using the manufacturing method according to claim 1. 38. A display device using the thin film transistor according to claim 37. 39. A liquid crystal display device using the thin film transistor according to claim 37.