JP2001044133A - Laser radiation method and manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the region where ununiform crystal property or the like due to overlap region exists by setting the width of gradient region to the value less than the minimum interval required among the regions, where a plurality of semiconductor devices are formed, to be formed with a semiconductor thin film or among the element groups forming the semiconductor device. SOLUTION: In the energy intensity distribution in the Y axis direction of the rectangular or line-shape laser beam, the energy intensity distribution Eg of the laser beam is almost trapezoidal shaped and almost all regions except for both ends keep fluctuation of energy intensity to the uniformity of almost ±3% or less. At both ends, the gradient regions are provided where energy intensity drops rapidly. The width Ws of this gradient region is set to the minimum interval or less required among the adjacent semiconductor devices, namely to about 1 mm or less. Shaping of the gradient region is performed with a laser shaping apparatus comprising an optical system for laser shaping such as a cylindrical lens or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device using a semiconductor thin film formed on a large-area insulating substrate, and more particularly, to a method for manufacturing a semiconductor thin film formed on a large-area insulating substrate. And technology for irradiating laser light.

[0002]

2. Description of the Related Art Conventionally, MOS is used for various electronic devices and the like.
Semiconductor devices have been used. A typical example is a MOS transistor (also referred to as a MOSFET or an insulated gate transistor). In addition, among electronic devices, in particular, a thin film transistor (hereinafter, referred to as a TFT) widely used as a semiconductor element for driving an active matrix liquid crystal display device, an image sensor, and the like.
Also has a portion similar in structure to a MOS transistor, and therefore can be included in a MOS type semiconductor device in a broad sense.

In particular, in recent years, there has been an increasing demand for miniaturization and high-speed operation of semiconductor devices. In TFTs, instead of amorphous silicon TFTs using an amorphous silicon thin film as an active layer, more field-effect transfer has been required. A polycrystalline silicon TFT using a highly polycrystalline silicon thin film has been developed.

The above-described polycrystalline silicon TFT has an active layer formed of a polycrystalline silicon thin film and is used as a switching element in a pixel region or an element constituting a peripheral circuit region of an active matrix type liquid crystal display device. A polycrystalline silicon thin film used for such a polycrystalline silicon TFT is required to have a high electric field mobility of 100 to 300 cm ² / V · sec or more.

Therefore, at present, a so-called laser annealing method for forming a high-quality polycrystalline silicon thin film by irradiating an amorphous silicon thin film with a short-wavelength pulse laser such as an excimer laser and heating it has been actively developed. Have been done.

In this laser annealing method, an amorphous silicon thin film is irradiated with a short-wavelength pulse laser to locally heat and melt, and then crystallized in a cooling process to obtain a polycrystalline silicon thin film. .

In addition to the laser annealing method, in addition to forming a polycrystalline silicon thin film by heating, when a contact region of a polycrystalline silicon TFT is formed, impurity ions are implanted into the contact region, and then the impurity ions are implanted. Are activated to reduce the resistance of the contact region.

[0008] As a laser irradiation method in the above-mentioned laser annealing method, generally, a spot-shaped laser beam is formed into a rectangular shape long in any direction by an optical system in which a plurality of lenses are combined, and the rectangular laser beam is formed. Light is intermittently irradiated while partially overlapping the light in the scanning direction. If the length in the long side direction is significantly longer than the length in the short side direction of the rectangular laser light, it may be called linear laser light.

As shown in FIG. 9, such a rectangular laser beam has a substantially trapezoidal energy intensity distribution in the short side direction and the long side direction thereof, and the energy intensity distribution is somewhat different. Generally. Needless to say, the energy intensity distribution is preferably as small as possible.

Therefore, conventionally, for example, Japanese Patent Application Laid-Open No. 9-2750
As disclosed in Japanese Patent Application Laid-Open No. 81-81, a method for making the energy intensity distribution in the long side direction of the rectangular laser light uniform has been proposed. Techniques for controlling the width of the gradient region in the energy intensity distribution have been proposed.

[0011]

As described above, a laser beam formed into a rectangular or linear shape has an energy intensity distribution, and in particular, a region having a gradient in the energy intensity distribution at an end. Have.

In this gradient region, the energy intensity gradually changes from near zero to an optimum value. In a region corresponding to the energy intensity gradient region in the semiconductor thin film irradiated with the laser light, the crystal grain size is small. It may be uneven. When such a region is included in, for example, a channel portion of a transistor, the performance of the transistor is deteriorated, and characteristics are different from those of a transistor which is not.

Therefore, conventionally, for example, Japanese Patent Application Laid-Open No. 8-34001
As disclosed in Japanese Patent Application Publication No. 18-18, attempts have been made to reduce the width of the gradient portion in the energy intensity distribution of the rectangular laser light in the short side direction as much as possible. Further, as disclosed in Japanese Patent Application Laid-Open No. 9-275081, for example, a method has been proposed in which the energy intensity distribution in the long side direction of a rectangular laser beam is made uniform. According to this, it is easy to make the characteristics between the elements arranged adjacently in the long side direction of the rectangular laser light uniform.

As shown in such prior art,
It is extremely important to make the energy intensity distribution of laser light uniform to obtain a good crystalline semiconductor thin film. However, due to recent research and development, by irradiating the laser light so as to overlap about 2 to 100 times with respect to the width in the short side direction of the laser light formed in a rectangular or linear shape along the scanning direction, It has been confirmed that the non-uniformity of the slope portion is greatly reduced. In addition, the energy intensity distribution in the long side direction is also uniformed in the same manner as in the short side direction by irradiating the laser beam so as to overlap about 2 to 100 times. Note that the number of times of irradiation depends on the shape of the energy intensity distribution in the short side direction of the laser beam, and there is an optimum value for obtaining a uniform crystalline semiconductor thin film, particularly for a width having a gradient at the end. The uniformity of the rectangular or linear laser light in the scanning direction in the scanning direction has been dramatically improved by a laser light shaping technique, a scanning method, and the like.

In the laser annealing method described above, the shape of the rectangular or linear shaped laser light irradiation surface is about 0.5 mm to several mm in the short side direction.
The long side direction is about several tens mm to about 300 mm. Therefore, when it is intended to uniformly heat the entire substrate on which the semiconductor thin film to be irradiated is deposited using such a rectangular or linear shaped laser beam, or when the substrate area is extremely small, etc. Except for this, the irradiation area of the laser beam is much smaller than the area of the substrate. Therefore, it is necessary to heat the entire substrate by scanning in a certain direction while overlapping a part of the laser light. FIG. 10 shows the situation at that time.

As shown in FIG. 10, for example, when manufacturing an active matrix type liquid crystal display device having a large area, it is impossible to heat the entire substrate only by one scan along the scanning direction. In parallel with the scanning direction,
5 scans need to be performed. In this case, an overlap region or a non-irradiation region having a certain width is provided between the irradiation regions adjacent in the long side direction.

Since a crystalline semiconductor thin film is not formed in the non-irradiated area, elements such as transistors cannot be formed in that area. Further, the overlapping region is obtained by superposing the gradient regions in the long side direction, and is not irradiated differently from the short side direction. Therefore, the region has a non-uniform crystalline semiconductor thin film formed in a belt shape. for that reason,
Conventionally, such a region has not been used as a region for forming an element such as a transistor.

This band-shaped region does not occur when a certain portion of the substrate is locally heated as in the past. Further, in the case where the area of the substrate is extremely small and the entire substrate can be heated by once scanning with the laser beam, the strip-shaped region is formed at the edge of the substrate, and has been ignored with almost no influence.

That is, the laser annealing method is originally intended to heat a substrate having a very small area or a very small portion on the substrate. In particular, there is no other way than to consider the existence of the overlapping area in the long side direction.

In the laser light currently in practical use, the gradient region in the short side direction in the energy intensity distribution is controlled to about 10 μm to 500 μm. On the other hand, the gradient area in the long side direction is about several mm to 10 mm, which is larger than that in the short side direction. Therefore, at present, a band-shaped overlap region is formed in a range of approximately several mm to 10 mm. When 2-5 scans are performed on the substrate using such a laser beam, the ratio of the band-shaped region to the area of the substrate is not negligible.

In order to obtain more effective areas in the substrate, it is necessary to minimize such band-shaped non-uniform areas parallel to the scanning direction. For example, when manufacturing an active matrix type liquid crystal display device, a flexible terminal area for electrically connecting an external circuit and a panel, a hardened resin seal area for bonding an opposing substrate, and a division for each panel. In consideration of a necessary area and the like, an area of at least about 1 mm may be provided between adjacent panels. However, it is necessary to dispose the area so as to avoid a band-shaped area on the substrate. The size and the number of panels to be mounted on the board are greatly restricted.

The present invention has been made in view of the above-described problems of the prior art, and has been made in consideration of the above-described problems, and is directed to laser irradiation capable of reducing a non-uniform region such as crystallinity due to an overlapping region in a long side direction of a laser beam. A method and a method for manufacturing a semiconductor device are provided.

[0023]

Means for Solving the Problems In order to solve the above-mentioned problems, a laser irradiation method according to the present invention irradiates a semiconductor thin film formed on an insulating substrate with laser light,
A laser irradiation method for heating the semiconductor thin film,
In the laser irradiation method, the laser light is shaped into a linear or rectangular shape, and the laser light is intermittently irradiated while scanning in a certain direction so as to partially overlap an irradiation region on the surface of the semiconductor thin film with the laser light. In the irradiation, a plurality of semiconductor devices having a gradient region in which the energy intensity distribution is inclined at a long-side direction end portion of the laser beam, and having a width of the gradient region formed by the semiconductor thin film. It is characterized in that the distance is set to be equal to or less than a required minimum distance between regions to be formed or between element groups constituting a semiconductor device.

Further, the irradiation area has an overlap area where the gradient area at least partially overlaps between the irradiation areas adjacent in the long side direction of the laser beam.

Further. The width of the overlap region is approximately one to two times the width of the gradient region.

In order to solve the above-mentioned problems, a method of manufacturing a semiconductor device according to the present invention includes a laser irradiation step of irradiating a semiconductor thin film formed on the insulating substrate with laser light to heat the semiconductor thin film. In the method for manufacturing a semiconductor device having, in the laser irradiation step, the laser light is formed into a linear or rectangular shape, and the width of a gradient region in which the energy intensity distribution at the end in the long side direction of the laser light is inclined is Using a laser beam that is equal to or less than a necessary minimum interval between regions where a plurality of semiconductor devices formed by the semiconductor thin film are to be formed or between element groups constituting the semiconductor device, and using the laser light on the surface of the semiconductor thin film. The irradiation area is intermittently irradiated while scanning in a certain direction so as to partially overlap the irradiation area, and the irradiation area is a long side of the laser light during the irradiation. Between the irradiation regions adjacent to each other in the direction, the gradient region has an overlapping region at least partially overlapping, and the overlapping region is formed by the semiconductor thin film after heat treatment by laser irradiation or a region where the semiconductor thin film does not exist. It is characterized in that it matches a region where no structure exists.

Further, the semiconductor device is an active matrix type liquid crystal display device having a display region and a drive circuit region formed on the same substrate, wherein the overlap region is made coincident with a gap between the display region and the drive circuit region. It is characterized by:

Hereinafter, the operation of the present invention will be described in detail.

According to the laser irradiation method of the present invention, the width of the gradient region of the energy intensity at the end of the laser beam in the long side direction is changed between the regions where a plurality of semiconductor devices formed by the semiconductor thin film are to be formed or By setting the distance between the element groups constituting the semiconductor device to be equal to or less than the required minimum distance, it is possible to reduce a band-like region in which the crystallinity of the semiconductor thin film generated when the laser light scans over the substrate is not uniform.

In addition, by providing an overlapping area in which each of the illuminated areas is overlapped with the adjacent illuminated area in the long side direction of the laser beam, the crystallinity of the semiconductor thin film in the inclined area is improved. At the same time, the width of the band-like region having non-uniform crystallinity can be reduced.

Further, by making the width of the overlapping region approximately one to two times the width of the gradient region, the variation in the crystallinity of the semiconductor thin film in the overlapping region is minimized, and at the same time, the band-like region having non-uniform crystallinity is formed. The width can be reduced. Therefore, when the effective area on the substrate is increased and the crystal region of the band region satisfies the required specifications, a semiconductor device can be manufactured regardless of the presence or absence of the band region.

Further, according to the method of manufacturing a semiconductor device of the present invention, the above-described laser light is used to match an overlapping region where the gradient regions overlap with a region where no semiconductor thin film exists or a region where a structure is not formed by the semiconductor thin film. Accordingly, a plurality of semiconductor devices can be formed on a substrate with extremely high density. That is, according to the present invention, the width of the gradient region in the long side direction of the laser beam is equal to or less than the minimum interval required between the regions where the semiconductor device is to be formed or the element groups constituting the semiconductor device. It is extremely easy to arrange the semiconductor device while avoiding the overlapping area where. Further, even when the overlapping region passes through the region where the semiconductor device is to be formed, the influence can be avoided by matching the overlapping region between the element groups constituting the semiconductor device.

According to the method of manufacturing a semiconductor device of the present invention, the semiconductor device is an active matrix type liquid crystal display device in which a display region and a drive circuit region are formed on the same substrate. By matching the gap with the circuit region, a plurality of drive circuit integrated type active matrix type liquid crystal display devices can be formed on the substrate at extremely high density. That is, according to the present invention, the width of the gradient region in the long side direction of the laser beam is equal to or less than the minimum interval required between the regions where the semiconductor device is to be formed or the element groups constituting the semiconductor device. It is extremely easy to dispose an active matrix type liquid crystal display device integrated with a drive circuit while avoiding an overlapping area where the liquid crystal display overlaps.
Further, even when the overlapping area passes through the area where the active matrix type liquid crystal display device integrated with the driving circuit is to be formed, the influence is avoided by matching the overlapping area between the display area and the driving circuit area. Can be.

For example, if the width of the gradient region is 1 mm or less and the width of the overlap region is also 1 mm or less, the overlap region coincides between the display region and the drive circuit region of the drive circuit integrated type active matrix liquid crystal display device. It is possible to do.

As described above, according to the present invention, when a semiconductor thin film is irradiated with a laser beam while partially overlapping, and the semiconductor thin film is subjected to a heat treatment such as crystallization or activation, the uniformity is reduced. It is possible to effectively utilize the entire substrate without being affected by the shape and scanning direction of the laser beam, and to dramatically improve the degree of freedom in the arrangement and design of the semiconductor device and the like.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a laser irradiation method of the present invention and a method of manufacturing a semiconductor device using the same will be described below in detail with reference to the drawings. In the present embodiment, an active matrix liquid crystal display device and a polycrystalline silicon TFT formed on a glass substrate or the like will be described as examples of a semiconductor device and a semiconductor element constituting the semiconductor device. Not something.

Embodiment 1 FIG. 1 is a conceptual diagram showing an example of a laser annealing apparatus that can be used in the present invention. According to FIG. 1, first, a laser beam 11 is oscillated by a laser oscillator 1. The laser light oscillated by the laser oscillator 1 is mainly a XeCl excimer laser (wavelength 308).
nm, pulse width 20 to 50 ns), but depending on the type of laser oscillator, other excimer lasers (such as KrF)
And other types of laser light can be oscillated.

Laser light 11 oscillated by laser oscillator 1
Are, in order, the energy attenuating device 2, the total reflection mirrors 3, 4,
5. By passing through the laser shaping device 6, the initial 4
The shape of a rectangular laser beam of about 3 cm ² is finally elongated on the substrate 10 with a length (long side) of about 50 mm to about 300 mm and a width (short side) of about 0.5 mm to about 2 mm.
It is processed into a rectangular or linear laser beam.

The substrate 10 is transferred onto a stage 9 in a process chamber 8 and is heated by a laser beam through a quartz window 7.

Further, the stage 9 is provided with a driving mechanism, and can move the substrate in the X-axis (the short side direction of the laser beam) and the Y-axis (the long side direction of the laser beam). Further, a driving mechanism may be provided in the laser beam shaping device 6 so as to move the Y-axis. In this case, the volume of the process chamber 8 can be reduced. The stage 9 can be provided with a heating mechanism. In this case, the substrate 10 can be heated to about 400 ° C.

Although not shown, the process chamber 8
If necessary, a gate valve, vacuum pump, or the like to maintain the inside of the chamber in a vacuum or inert gas atmosphere
A gas supply line or the like is connected.

FIG. 2 shows the relationship between the short side and long side of a rectangular or linear laser beam and the scanning direction. FIG.
According to the above, the X-axis direction of the laser beam 11 is a short side, and the Y-axis direction is a long side. At this time, the laser beam 11 is emitted from the Z-axis direction.

The laser beam 11 is irradiated about 2 to 100 times while partially overlapping the irradiation area with the width W1 of the short side. That is, scanning is performed in the X-axis direction at a pitch of 1/2 to 1/100 of the width W1 of the short side. If the area of the substrate is large,
If the entire surface of the substrate cannot be irradiated by the scanning of the first row, the irradiation area is moved in the Y-axis direction, and the scanning of the second row is performed by partially overlapping the irradiation area in the long side direction. If it is not enough,
In the same procedure, the third and fourth rows to be scanned may be sequentially increased.

FIG. 3 shows a rectangular or linear laser beam Y.
It shows the energy intensity distribution in the axial direction. FIG.
In the graph, the vertical axis represents the energy intensity, and the horizontal axis represents the length in the Y-axis direction (both are arbitrary units).

According to FIG. 3, the energy intensity distribution Eg of the laser beam is substantially trapezoidal, and most of the region except for both ends is
The variation in energy intensity is maintained at a uniformity of about ± 3% or less. And, at both ends, there is a gradient region where the energy intensity sharply decreases. According to the present invention, the width Ws of the gradient region is set to be equal to or less than the minimum distance required between adjacent semiconductor devices, and is generally equal to or less than 1 mm. The shaping of the gradient region is performed by a laser shaping device including a laser shaping optical system such as a cylindrical lens.

FIG. 4 shows the relationship between the scanning direction of a rectangular or linear laser beam and the substrate. According to FIG. 4, the laser beam 11 is applied to the substrate 40 in the X-axis direction.
Scanning is performed from the end of 0 to the end on the opposite side, and the first scan (first row) 41 is completed.

If the entire substrate cannot be irradiated by one scan, a second (second column) scan 42 is performed. On this occasion,
The irradiation area is moved in the Y-axis direction, and scanning is performed in a state where the irradiation area is overlapped by the width Wov.

By thus increasing the number of scanning rows, a substrate having an arbitrary area can be heated. For example, when the length of the long side of the laser beam 11 is 100 mm, a substrate having a side of about 200 mm can be heated by performing two rows of scanning, and a substrate having a side of about 300 mm can be heated by performing three rows of scanning. It becomes possible. The length of the long side of the laser beam 11 is 1
In the case of 50 mm, two lines are scanned so that one side is about 30 mm.
0mm substrate, about 450m on one side by scanning in 3 rows
m, and the length of the long side of the laser beam 11 is 300 m
In the case of m, one side is about 600 mm by performing two-row scanning.
Substrate can be heated.

FIG. 5 shows the energy intensity distribution of the laser light adjacent in the scanning direction, and FIG. 6 shows the crystallinity distribution of the semiconductor thin film irradiated with the laser light shown in FIG. It is. 5 (a), 5 (b), 5 (c)
Correspond to FIGS. 6A, 6B, and 6C, respectively.

In FIG. 5, the vertical axis indicates the energy intensity, and the horizontal axis indicates the distance in the Y-axis direction (both are arbitrary units). In FIG. 6, the vertical axis indicates crystallinity, and the horizontal axis indicates the length in the Y-axis direction (both are arbitrary units). In addition, as an index indicating the crystallinity, the size of a crystal grain, the crystallization rate, the mobility of a semiconductor element, and the like can be used.

5 and 6, the distance Wd
Represents the distance between the points where the gradients of the ends of the energy intensity distributions Eg1 and Eg2 of the adjacent laser beams in FIG. 5 start.

FIG. 5A shows a case where the ends of the two laser beams do not overlap. In this case, the distance Wd between adjacent laser beams is equal to the energy intensity distributions Eg1 and Eg1.
The length is the sum of the widths Ws of the gradient regions at g2. The distance Wd at this time is, for example, about 2 mm when the width of the gradient region of the laser beam is 1 mm. At this time, since the laser beams do not overlap, the width W of the overlap region is
ov is 0 mm.

FIG. 6A shows the crystallinity at this time. The continuity of the crystalline Cr1 and Cr2 in the adjacent portion of the laser beam is interrupted at a distance equal to or less than the distance Wd, and a band-like region having extremely non-uniform crystallinity occurs.

FIG. 5B shows a case where the ends of the two laser beams partially overlap. In FIG. 5B, the overlap amount is set to be substantially the same as the width Ws of the gradient region. The distance Wd at this time is about 1 mm when the width of the gradient region of the laser beam is 1 mm, for example. Also, the width Wo of the overlapping area at this time
v is about 1 mm because the bottoms of the gradient regions completely overlap.

FIG. 6B shows the crystallinity at this time. The continuity of the crystalline Cr1 and Cr2 in the adjacent portion of the laser beam is maintained at a distance equal to or less than the distance Wd, and the band-like region having non-uniform crystallinity is reduced. The crystallinity of the region at the distance Wd is slightly lower than the average value of the other regions, but can be controlled within a range of about -5% or less.

FIG. 5C shows a case where the ends of the two laser beams are further overlapped. In FIG. 5C, FIG.
The amount of overlap was increased as compared to (b) to the point where the gradient started. The distance Wd at this time is 0 mm. In addition, the width Wov of the overlapping area at this time is about 2 mm because the points where the gradient starts are overlapped.

FIG. 6C shows the crystallinity at this time. In the continuity of the crystalline Cr1 and Cr2 in the adjacent portion of the laser beam, a band-shaped non-uniform region is generated at the distance Wd. Further, the crystallinity at the point of the distance Wd shows a value slightly higher than the average value of the other regions, but can be controlled within a range of approximately + 5% or less.

Further, if the overlapping amount is further increased as compared with FIG. 5C, a non-uniform band-like region having greatly different crystallinity is generated at the portion of the distance Wd shown in FIG. 6C. Since this region deviates from the allowable range of variation in crystallinity, it is difficult to actually use this region.

As described above, if the adjacent laser beams do not overlap at all, the semiconductor thin film in that region is not sufficiently crystallized, and the crystallinity becomes discontinuous. In addition, if the gradient regions are overlapped by a certain amount, although the non-uniformity remains slightly, the allowable range of the variation in crystallinity does not largely deviate.

In the present invention, the width of the gradient region of the energy intensity in the long side direction of the laser beam is set to approximately 1 mm or less, and the distance between the adjacent laser beams is approximately set to be equal to that shown in FIGS.
By setting the width of the overlapping region of the laser beam within the range of (c), that is, about 1 to 2 times the width of the gradient region, the width of the band-shaped non-uniform region parallel to the scanning direction is extremely small. It is possible to do.

Although not shown, FIG. 5A and FIG.
In the intermediate state of (b), that is, when the width of the overlapping region is less than one time the width of the gradient region, the crystallinity of this region deviates from the allowable range of the variation, so that it is difficult to actually use it. Become.

FIG. 7 shows a relationship between a region where a semiconductor device laid out on a substrate is to be formed and a laser beam. As shown in FIG. 7, a first scan 71 and a second scan 72 are performed on an area 75 where a semiconductor device laid out on a substrate 70 is to be formed.
3 can be provided.

In the present invention, the width Wov of the overlapping area is approximately 1
mm or less, the entire substrate can be used effectively. Further, if the width Wov of the overlapping region is 1 mm or less, the overlapping region 73 may be disposed in a region where a semiconductor element or the like is not finally formed even in a region where a semiconductor device is to be formed. It is possible.

FIG. 7 also shows an example in which an overlap region is arranged in a region where a semiconductor device is to be formed. In FIG. 7, an overlap region 73 is arranged between element group formation regions 76 in a region where a semiconductor device is to be formed. For example, if it is an active matrix type liquid crystal display device,
An overlapping area can be arranged in a gap between the pixel area and the peripheral circuit area.

If the continuity of the crystallinity of the overlapping region satisfies the specifications of the semiconductor device to be manufactured, a region where the semiconductor device is to be formed can be laid out regardless of the presence or absence of the overlapping region. is there.

FIG. 8 shows T as an example of a semiconductor element constituting a semiconductor device manufactured by using the manufacturing method of the present invention.
FIG. 3 is a cross-sectional view of the FT.

Hereinafter, a method of manufacturing the TFT will be briefly described. First, a base film 91 having a thickness of 20 to 500 nm was deposited on a substrate 90 made of glass or the like by a sputtering method. As the base film 91, a SiO ₂ film, a SiNx film, or the like can be used.

Further, an amorphous silicon thin film having a thickness of 20 to 150 nm is deposited thereon by plasma CVD or low pressure CVD using monosilane or disilane as a raw material.

When the amorphous silicon thin film has a large hydrogen content such as when an amorphous silicon thin film is deposited by a plasma CVD method, dehydrogenation annealing may be performed in a firing furnace or the like.

Next, XeC was applied to this amorphous silicon thin film.
l Excimer laser (wavelength 308nm, pulse width 50n
Irradiated with s) and crystallized to form a polycrystalline silicon thin film. The energy density of laser light is 300-400mJ
/ Cm ² and 10 to 40 shots. Thereafter, the polycrystalline silicon thin film was patterned into a predetermined shape, for example, an island shape.

Next, a 50-200 nm-thick SiO ₂ film is formed by sputtering or CVD to cover these island-like regions.
This was used as the gate insulating film 92. Then, 20
An aluminum film having a thickness of 0 nm to 5 μm was formed by a sputtering method, and was patterned to form a gate electrode 93 in each island region.

Thereafter, impurity ions were implanted into the island-like polycrystalline silicon thin film of each TFT by ion doping in a self-aligned manner using the gate electrode 93 as a mask. At this time, in the case of a P-type TFT, diborane (B ₂ H ₆ ), N
In the case of a type TFT, phosphine (PH ₃ ) was used as a doping gas.

Next, a XeCl excimer laser (wavelength 3
08 nm and a pulse width of 50 ns), and the impurity region was introduced to activate the crystallinity-deteriorated portion to improve the crystallinity. As a result, an N-type or P-type contact region 94 and a channel region 95 are formed.

Next, an SiO ₂ film having a thickness of 3 is formed on the entire surface as a first interlayer insulating film 96 by sputtering or CVD.
It was formed to a thickness of 00 to 1000 nm. In the plasma CVD method using TEOS as a raw material, SiO with good step coverage is used.
_Two films are obtained.

Thereafter, a contact hole was opened in a portion corresponding to the contact region 94 of the interlayer insulating film 96, and a source electrode 97 and a drain electrode 98 were formed. These electrodes may be multilayer electrodes with low sheet resistance and aluminum with chromium or titanium nitride as a base.

Next, an SiNx film having a thickness of 3 is formed on the entire surface as a second interlayer insulating film 99 by sputtering or CVD.
It was formed to a thickness of 00 to 1000 nm. In the plasma CVD method using TEOS as a raw material, SiN having good step coverage is used.
An x film is obtained.

Then, in hydrogen at atmospheric pressure, 300 to 500
C. for 1 to 4 hours to reduce dangling bonds in the silicon film.

Thus, a TFT was completed. When this TFT is used for a liquid crystal display device or the like,
A contact hole is opened in a portion of the interlayer insulating film 99 corresponding to the drain electrode 98, and an ITO film having a thickness of 50 to 200 nm is formed as a pixel electrode by a sputtering method.

The present invention is used in crystallization and activation by heating with a laser beam by the above-described manufacturing process, and produces an effect.

The above-described manufacturing process is an example, and the present invention is not limited to this. In addition, it goes without saying that the present invention is not limited by any other manufacturing process other than the laser irradiation process.

[0081]

As described above, according to the present invention, it is possible to reduce a non-uniform region in a semiconductor thin film caused by laser irradiation and to improve the degree of freedom in designing and arranging a semiconductor device on a substrate. An object of the present invention is to provide a laser irradiation method that can be used and a method for manufacturing a semiconductor device using the same.

According to the present invention, the width of the gradient region at the end in the long side direction of the laser beam is set to the width between the regions where a plurality of semiconductor devices formed by the semiconductor thin film irradiated with the laser beam are to be formed. Less than the minimum spacing required for
mm or less, this gradient region is overlapped with the gradient region in the adjacent irradiation region, and irradiation is performed on the semiconductor thin film, thereby reducing the width of the band-like region where the crystallinity and the like in the semiconductor thin film become non-uniform. it can.

As a result, a portion where a semiconductor device or the like has not been conventionally formed can be used, and the entire substrate can be used to the maximum. Therefore, it is possible to easily and efficiently arrange the semiconductor devices and the like on the substrate without being affected by the length, shape, scanning direction, and the like of the long side direction of the laser light. For example, if the present invention is applied to an active matrix type liquid crystal display device or the like, the number of panels produced (the number of panels) per substrate can be increased, and the productivity is greatly improved.

As described above, the present invention realizes efficient heat treatment of a large-area substrate by the laser annealing method, and is a semiconductor device which is indispensable to the information society in the future, especially a driving circuit. It is possible to greatly improve the productivity of the integrated image display device, and to greatly improve the performance and added value of a portable device or the like equipped with the integrated image display device.

[Brief description of the drawings]

FIG. 1 is a view showing the concept of a laser annealing apparatus according to the present invention.

FIG. 2 is a diagram illustrating a relationship between a short side and a long side of a laser beam and a scanning direction according to the present invention.

FIG. 3 is a diagram showing an energy intensity distribution in a long side direction of a laser beam according to the present invention.

FIG. 4 is a diagram showing a relationship between a scanning direction of a laser beam and a substrate according to the present invention.

FIG. 5 is a diagram showing an energy intensity distribution in a boundary region between a laser beam according to the present invention and another adjacent row of laser beams.

FIG. 6 is a diagram showing a crystallization distribution in a boundary region between a laser beam according to the present invention and another adjacent row of laser beams.

FIG. 7 is a diagram showing an arrangement of a region irradiated with a laser beam according to the present invention and a region where an element group is to be formed.

FIG. 8 is a cross-sectional view showing an example of a TFT according to the manufacturing method of the present invention.

FIG. 9 is a diagram showing a conventional technique.

FIG. 10 is a diagram showing a conventional technique.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 laser oscillator 2 energy attenuator 3, 4, 5 total reflection mirror 6 laser shaping device 7 quartz window 8 process chamber 9 stage 10, 40, 70, 90 substrate 11 laser beam W1 width of short side of laser beam W2 laser beam Width of long side Eg, Eg1, Eg2 Energy intensity distribution of laser beam in Y-axis direction Ws Width of gradient area 41, 71 First scan (first column) 42, 72 Second scan (second column) 43 , 73 overlapping region 44, 74 band region Wov width of overlapping region Wd distance Cr1, Cr2 crystallinity in the Y-axis direction of laser light 75 semiconductor device formation planned region 76 element group formation region 91 base film 92 gate insulating film 93 gate electrode 94 Contact region 95 channel region 96 first interlayer insulating film 97 source electrode 98 drain electrode 99 second interlayer insulating film

Continued on the front page F-term (reference) 2H092 JA24 KA05 KA10 MA05 MA07 MA27 MA29 MA30 NA25 NA29 PA07 5F052 AA02 AA17 BA07 BB07 DA02 DB02 DB03 FA01 JA01 JA10 5F110 AA18 BB01 CC02 DD02 DD13 DD14 DD24 EE03 GG24 GG02 GG28 GG47 HJ01 HJ12 HJ23 HL03 HL04 HL11 HM18 NN03 NN04 NN23 NN24 NN34 NN35 NN40 PP03 PP04 PP06 PP35 QQ11 QQ19

Claims (5)

[Claims] 1. A laser irradiation method for irradiating a semiconductor thin film formed on an insulating substrate with a laser beam and heat-treating the semiconductor thin film, wherein the laser beam irradiation method comprises: Shape or a rectangular shape, and irradiating intermittently while scanning in a certain direction so that an irradiation area on the surface of the semiconductor thin film by the laser light partially overlaps. At the end in the long side direction of the light, there is a gradient region in which the energy intensity distribution is inclined, and the width of the gradient region is formed between a region where a plurality of semiconductor devices formed by the semiconductor thin film are to be formed or a semiconductor device. A laser irradiation method characterized in that the distance is set to be equal to or less than a required minimum interval between the element groups to be performed. 2. The irradiation region has an overlapping region in which the gradient region at least partially overlaps between irradiation regions adjacent in a long side direction of the laser light. 2. The laser irradiation method according to 1. 3. The laser irradiation method according to claim 2, wherein the width of the overlap region is made approximately one to two times the width of the gradient region. 4. A method for manufacturing a semiconductor device, comprising: a laser irradiation step of irradiating a semiconductor thin film formed on an insulating substrate with a laser beam to heat the semiconductor thin film. The width of the gradient region in which the energy intensity distribution at the end of the laser light in the long side direction is inclined is formed between the regions where a plurality of semiconductor devices to be formed by the semiconductor thin film are to be formed or Intermittent scanning is performed while scanning in a certain direction so as to partially overlap an irradiation area on the surface of the semiconductor thin film with the laser light while using a laser light that is equal to or less than a required minimum interval between the element groups constituting the semiconductor device. In the irradiation region, at the time of the irradiation, at least a part of the gradient region is between irradiation regions adjacent in a long side direction of the laser light. It has a plurality of overlapping regions, and the overlapping region coincides with a region where the semiconductor thin film does not exist or a region where a structure formed by the semiconductor thin film does not exist after heat treatment by laser irradiation. Semiconductor device manufacturing method. 5. The active matrix type liquid crystal display device according to claim 1, wherein the display region and the drive circuit region are formed on the same substrate, and the overlap region coincides with a gap between the display region and the drive circuit region. The method for manufacturing a semiconductor device according to claim 4, wherein: