JPH07307304A - Laser processing method for semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate irregularity caused by overlapping of a laser beam, by irradiating the whole part of a circuit region mainly consisting of an analog circuit, with laser light without moving the laser light, and scanning the circuit region with the laser light which has few analog element. CONSTITUTION:A laser beam 15 is set as a size sufficient to irradiate the whole part of a column driver 13, and a substrate is so moved that the column driver is irradiated with laser light. After that, the substrate is irradiated with the laser light without moving a laser beam and the substrate. After that, the position which is to be irradiated with the laser light is shifted downward, and the substrate is moved until the upper ends of an active matrix region 14 and a scan driver 12 are irradiated with the laser beam 15. The substrate is moved while irradiated with the laser light. Thus the substrate is scanned with the laser light as far as the lower end, and the scan driver 12 and the active matrix region 14 are irradiated with the laser light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser light irradiation treatment (so-called laser annealing method) in a semiconductor device manufacturing process. In particular, the present invention is a semiconductor material which is partially or wholly composed of an amorphous component, or a substantially intrinsic polycrystalline semiconductor material, and further, which is damaged by ion irradiation, ion implantation, ion doping, or the like. The present invention relates to a method for improving crystallinity of a semiconductor material or recovering the crystallinity by irradiating a semiconductor material whose crystallinity is significantly impaired with laser light.

[0002]

2. Description of the Related Art In recent years, much research has been conducted on lowering the temperature of semiconductor device processes. The big reason is
This is because it becomes necessary to form a semiconductor element on an insulating substrate such as glass. In addition, there are demands for miniaturization of elements and multilayering of elements. In the semiconductor process, crystallizing an amorphous component contained in a semiconductor material or crystallizing an amorphous semiconductor material, or crystallinity of a semiconductor material whose crystallinity is lowered due to irradiation of ions It is necessary to recover the crystallinity or to improve the crystallinity though it is crystalline.
Conventionally, thermal annealing has been used for this purpose. When silicon is used as the semiconductor material,
By performing annealing at a temperature of 600 ° C. to 1100 ° C. for 0.1 to 48 hours or longer, crystallization of amorphous, recovery of crystallinity, improvement of crystallinity and the like have been performed.

[0003] In such thermal annealing, generally, the higher the temperature, the shorter the processing time may be, but at a temperature of about 600 ° C, a long processing time is required. Therefore, from the viewpoint of lowering the process temperature, it has been necessary to replace the step conventionally performed by thermal annealing with another means. Laser light irradiation technology is drawing attention as the ultimate low temperature process. That is, the laser light can be applied to only the places where high energy comparable to thermal annealing is required, and it is not necessary to expose the entire substrate to high temperature. Regarding the irradiation of laser light, two methods have been roughly divided and proposed.

The first method uses a continuous wave laser such as an argon ion laser and irradiates a semiconductor material with a spot-like beam. This is a method of crystallizing the semiconductor material by melting the semiconductor material and then slowly solidifying it due to the difference in energy distribution inside the beam and the movement of the beam. Second
Is a method of crystallizing the semiconductor material by irradiating the semiconductor material with a high-energy laser pulse using a pulsed laser such as an excimer laser, instantaneously melting and solidifying the semiconductor material.

[0005]

The problem of the first method is that the processing takes a long time. This is because the maximum energy of the continuous wave laser is limited and the size of the beam spot is at most mm. On the other hand, in the second method, the maximum energy of the laser is very large, so that it was possible to further improve the mass productivity by using a large spot of several cm ² or more.

However, in the case of irradiating a pulsed laser, even if the uniformity of energy in the beam of one shot pulse can be achieved by the improvement of the optical system, the variation of the characteristics of the element due to the overlapping of the pulses is improved. It was difficult. Especially when the element is located just at the end of the laser beam, the characteristics of the element (especially MO
The threshold voltage of the S transistor) varied considerably. As for semiconductor devices, the threshold voltage variation is considerably tolerated in digital circuits, but the threshold voltage variation of adjacent transistors may be required to be 0.02 V or less in analog circuits. It was

[0007]

The present invention has been made for the purpose of solving this problem. In order to eliminate the variation due to the overlapping of the laser beams, ideally, laser light irradiation is performed with a large beam that can collectively irradiate the entire circuit, but this is not possible in reality. Therefore, in the present invention, by dividing on the substrate into a relatively narrow region where the laser beams do not overlap and a relatively wide region where the laser beams overlap,
As a whole, ensure that sufficient characteristics are obtained.

In the present invention, the circuit on the substrate is divided into a circuit region centering on the analog circuit and a circuit region having a thin analog element, and the size of the laser beam is focused on the analog circuit. It is made larger than the circuit area described above, and the laser light can be irradiated to the entire circuit area centering on the analog circuit without substantially moving the laser light. Then, in the circuit area centering on the analog circuit, the laser light is emitted substantially without moving the laser. That is, in the circuit area centered on analog circuits,
There should be virtually no overlap of laser beams.

On the other hand, in the circuit area where the analog elements are thin, the laser light is irradiated by scanning the laser light. As a result, laser beams overlap in this region. For example, in a liquid crystal display (monolithic liquid crystal display) in which an active matrix circuit and a peripheral circuit (driver circuit) for driving the active matrix circuit are formed on the same substrate, the circuit area centering on the analog circuit is active. Driver circuit that drives the matrix,
Among them, it is a source driver (column driver) circuit that outputs an analog signal. On the other hand, the circuit region having a thin analog element is an active matrix circuit or a gate driver (scan driver) circuit.

In order to carry out the present invention, it is necessary to match the shape of the laser beam to such a circuit, or to match the shape of the circuit to the laser beam, but generally a linear or rectangular shape is required. Is desirable. Further, for example, since the column driver and the scan driver of the liquid crystal display are formed substantially orthogonal to each other, the direction of the laser beam may be changed to perform these processes, or the direction of the substrate may be rotated about 1/4 rotation. (More generally, (n / 2 + 1/4) (where n is a natural number) rotations) may be performed.

[0011]

By performing the above processing, the analog circuit regions cannot overlap with each other, and the in-plane uniformity of the laser beam is the only control. As a result, by sufficiently improving the in-plane uniformity of the laser beam,
An element with uniform characteristics can be formed. On the other hand, in a circuit area where analog elements are thin, variations in characteristics due to overlapping laser beams are unavoidable, but in the first place, such variations allow a little variation, so there is practically no problem. .

As described above, according to the present invention, it is possible to improve the characteristics of the circuit as a whole formed on the substrate by eliminating the adverse effects caused by the overlapping of the laser beams. In the present invention, the shape of the object to be irradiated with the laser may be a film shape having no pattern, or may be a substantially completed shape of the device. Hereinafter, the present invention will be described in more detail with reference to examples.

[0013]

【Example】

Example 1 FIG. 4 shows a conceptual diagram of the laser annealing apparatus used in this example. The laser light is oscillated by the oscillator 42, passes through the total reflection mirrors 45 and 46, and then the amplifier 4
Amplified by 3, and further introduced into the optical system 44 via the total reflection mirrors 47 and 48. The beam of the laser light up to that time is a rectangle of about 30 × 90 mm ² , but this optical system 64 allows a length of 100 to 300 mm and a width of 10 to 3 mm.
It is processed into an elongated beam of 0 mm. The maximum energy of the laser beam that passed through this optical system was 30 J / shot.

The optical path inside the optical system 44 is shown in FIG. The laser light incident on the optical system 44 passes through a cylindrical concave lens A, a cylindrical convex lens B, a horizontal fly-eye lens C, and a vertical fly-eye lens D. By passing through the fly-eye lenses C and D, the laser light changes from the Gaussian distribution type to the rectangular distribution. Further, the light passes through the cylindrical convex lenses E and F, is focused by the cylindrical lens H via the mirror G (mirror 59 in FIG. 5), and is irradiated onto the sample.

In this embodiment, the distance X in FIG.₁, X₂Firmly
Virtual focus I (this is due to the difference in the curved surface of the fly-eye lens).
Distance between the mirror G and the mirror G)
Distance X ₃, And distance X_Four, X_FiveAnd to adjust the magnification M and focus
The distance F was adjusted. That is, between these, M = (X₃+ X_Four) / X_Five, 1 / F = 1 / (X₃+ X_Four) + 1 / X_Five, Has a relationship. In this embodiment, the total optical path length X₆Is
It was about 1.3 m.

By using the beam processed into such a slender beam, the laser processing capability is dramatically improved. That is, after the strip-shaped beam exits the optical system 44, it passes through the total reflection mirror 49 and is irradiated onto the sample 51. However, since the width of the beam is about the same as or longer than the width of the sample, after all, , The sample may be moved in only one direction. Therefore, the sample stage and the driving device 50 have a simple structure and are easy to maintain. Further, the alignment operation when setting the sample is easy. In the present invention, in addition to the movement in one direction, it may have a function of rotating the sample.

On the other hand, if the beam is close to a square, it is not possible to cover the entire surface of the substrate by itself, so the sample must be moved two-dimensionally in the vertical and horizontal directions. . However, in that case, the driving device of the stage becomes complicated, and the alignment must be performed two-dimensionally, which is difficult. In particular, when the alignment is performed manually, the time loss in the process is large and the productivity is reduced. Note that these devices need to be fixed on a stable mount 41 such as an anti-vibration base.

Incidentally, the laser device as described above may be constructed independently, or other device, for example, a plasma CV.
The multi-chamber may be combined with a D film forming apparatus, an ion implantation apparatus (or an ion doping apparatus), a thermal annealing apparatus, or another semiconductor manufacturing apparatus. In this embodiment, an active matrix type liquid crystal display device (AMLC
In D), a so-called monolithic AMLCD in which peripheral circuits for driving the active matrix circuit are also formed on the same substrate will be described.

In such a device, as shown in FIG. 1A, the area 14 of the active matrix circuit, the column driver 13 and the scan driver 12 are provided on the edge of the substrate 11. There is. Actually, at this laser irradiation stage, as is clear from the above process, there is only a uniform film on the substrate, but the position where the circuit is formed is shown for the sake of clarity. . The column driver 13 is also the scan driver 1
2 also has a shift register, but since the column driver outputs an analog signal, an amplifier (buffer circuit) for that is included. A like this
Among the elements used for the MLCD, the thin film transistor fabrication process was outlined below.

[1] Formation of a base silicon oxide film and an amorphous silicon film on a glass substrate, and / or application of a crystallization accelerator (such as nickel acetate) on the amorphous silicon film. [2] Crystallization of amorphous silicon film by solid phase growth (example of solid phase growth conditions: 550 ° C., 8 hours, in nitrogen atmosphere) [3] Laser treatment of crystallized silicon film (improvement of crystallinity [4] Formation of island-shaped silicon regions by etching silicon film [5] Formation of gate insulating film (silicon oxide) [6] Formation of gate electrode [7] Implantation of impurity elements (phosphorus, boron, etc.) Source /
Drain formation [8] Activation of implanted impurities by laser irradiation [9] Formation of interlayer insulator [10] Formation of electrodes on source / drain

This embodiment and the following Embodiments 2 and 3 relate to laser light irradiation [3] which is carried out in the above steps for the purpose of further enhancing the crystallinity of the polycrystalline silicon film.

FIG. 1 shows the laser processing process of this embodiment. In this embodiment, the laser beam 15 has a size large enough to irradiate the entire column driver 13, and is, for example, a rectangle having a width of 10 mm and a length of 300 mm. First, Fig. 1
As shown in (B), the substrate was moved so that the column driver was irradiated with laser light. At this stage, the substrate is not irradiated with laser light. Then, the laser beam was irradiated without substantially moving the laser beam and the substrate. Laser light irradiation was performed in the atmosphere, and the substrate temperature was 200 ° C. A KrF excimer laser (wavelength 248 nm) was used as the laser. Laser oscillation frequency is 10 Hz, laser light energy density is 30
The pulse of laser light was 0 mJ / cm ² and 10 shots. When the irradiation of laser light for the required number of shots was completed, the irradiation of laser light was stopped. (Fig. 1 (B))

After that, the position to be irradiated with laser light was shifted downward, and the substrate was moved to a position where the upper ends of the active matrix region 14 and the scan driver 12 were hit by the laser beam 15. (FIG. 1C) Then, the substrate was moved while irradiating the laser light. For example, the oscillation frequency of the laser was 10 Hz, the energy density of the laser light was 300 mJ / cm ² , and the scanning speed of the laser light was 10 mm / s. As a result, the laser beam 15 is displaced by 1 mm. Since the width of the beam is 10 mm, about 10 shots of laser light will be applied to one location. (Fig. 1 (D))

In this manner, the laser was scanned up to the lower end of the substrate, and the scan driver 12 and the active matrix region 14 were irradiated with laser light. (FIG. 1 (E)) In this example, the laser beams did not overlap in the column driver 13. As a result, the threshold voltage of the thin film transistor in the column driver has a very small variation, and is typically 0.01 V or less in the adjacent thin film transistor and 0.05 V or less in the column driver. Other properties were similar.
On the other hand, the laser beams overlapped on the scan driver 12 and the active matrix region 14. Therefore, for example, the variation in the threshold voltage of the thin film transistor in the scan driver 12 was about 0.1 V for adjacent ones, and was almost the same in the plane. The same applies to the active matrix region 14. However, such a variation does not hinder the operation of each circuit.

[Embodiment 2] FIG. 2 shows a laser treatment process of this embodiment. Also in this embodiment, the laser beam 25
Is a size large enough to irradiate the entire column driver 23, and is, for example, a rectangle having a width of 10 mm and a length of 200 mm. First, as shown in FIG. 2B, the substrate was moved so that the column driver was irradiated with laser light. At this stage, the substrate is not irradiated with laser light. afterwards,
Substantially without moving the laser beam and substrate,
Irradiated with laser light. Laser light irradiation was performed in the atmosphere, and the substrate temperature was 200 ° C. K as a laser
An rF excimer laser (wavelength 248 nm) was used.
The oscillation frequency of the laser was 10 Hz, the energy density of the laser light was 300 mJ / cm ² , and the pulse of the laser light was 10 shots. When the irradiation of laser light for the required number of shots was completed, the irradiation of laser light was stopped. (Fig. 2
(B))

After that, the position to be irradiated with the laser beam was shifted downward, and the substrate was moved to a position where the upper end of the active matrix region 24 hits the laser beam 25. Unlike the first embodiment, the scan driver 22 is prevented from being irradiated with laser light at this time. (FIG. 2C) Then, the substrate was moved while irradiating the laser light. For example, the oscillation frequency of the laser was 10 Hz, the energy density of the laser light was 250 mJ / cm ² , and the scanning speed of the laser light was 10 mm / s. As a result, the laser beam 25 shifts by 1 mm. Since the width of the beam is 10 mm, about 10 shots of laser light will be applied to one location. (Fig. 2 (D))

In this manner, the laser was scanned up to the lower end of the substrate, and the active matrix region 24 was irradiated with laser light. (FIG. 2 (E)) After that, the substrate was rotated ¼. In FIG. 2 (F), the dotted square 26 is the position of the first substrate. (Fig. 2
(F)) Then, as shown in FIG. 2G, the substrate was moved so that the scan driver 22 was irradiated with the laser light. At this stage, the substrate is not irradiated with laser light. . After that, the scan driver 22 was irradiated with laser light without substantially moving the laser beam and the substrate. Laser oscillation frequency is 10H
z, energy density of laser light is 300 mJ / c
The pulse of m ² and the laser beam was 10 shots. When the irradiation of laser light for the required number of shots was completed, the irradiation of laser light was stopped. (Fig. 2 (G))

In this embodiment, not only the column driver 23 but also the scan driver 22 did not overlap the laser beam. Further, in this embodiment, the driver circuit was irradiated with laser light of 300 mJ / cm ² , while the active matrix circuit was irradiated with 250 mJ.
/ Cm ² laser light was irradiated. This is to obtain a thin film transistor with a small leak current (leakage current when a reverse bias voltage is applied to the gate; also referred to as off current) in the active matrix circuit. On the other hand, in the driver circuit, since the thin film transistor is required to operate at high speed, the energy of laser light is increased,
I tried to get high mobility.

[Third Embodiment] FIG. 3 shows a laser processing step of the present embodiment. Unlike the first and second embodiments, the present embodiment relates to a monolithic liquid crystal display having driver circuits on the upper, lower, left, and right sides of a substrate.
Such a display activation process (“[8] Activation of implanted impurities by laser irradiation” in Example 1 ”
Equivalent to).

FIG. 6 shows an outline of the whole process of the substrate to be processed according to this embodiment. First, as a base oxide film 102 on a substrate (Corning 7059, 300 mm × 200 mm) 101, a thickness of 1000 to 5000 Å, for example,
A 2000 Å silicon oxide film was formed. As a method for forming this oxide film, a sputtering method in an oxygen atmosphere was used. However, in order to further improve mass productivity, TEOS may be formed by decomposing / depositing by plasma CVD. Also,
The silicon oxide film thus formed may be annealed at 400 to 650 ° C.

After that, an amorphous silicon film of 300 to 500 is formed by a plasma CVD method or an LPCVD method.
0Å, preferably 400 to 1000Å, for example 500
Å Deposit and place this in a reducing atmosphere at 550 to 600 ° C for 8
Allow to crystallize by standing for ~ 24 hours. In that case, a small amount of a metal element such as nickel that promotes crystallization may be added to promote crystallization. Further, this step may be performed by laser irradiation. Then, the crystallized silicon film was etched to form the island-shaped region 103. Further, a thickness of 700 to 1500Å, for example 1200Å
The silicon oxide film 104 was formed.

Thereafter, an aluminum (containing 1 wt% Si or 0.1-0.3 wt% Sc (scandium)) film having a thickness of 1000 Å to 3 μm, for example 5000 Å, is formed by a sputtering method, and this film is formed. Etching was performed to form the gate electrode 105 and the gate wiring 106. (Fig. 6 (A))

Then, an electric current is applied to the gate electrode 105 and the gate electrode 106 in an electrolytic solution to carry out anodization to obtain a thickness of 5
0 to 2500Å, for example 2000Å anodized oxide 1
07 and 108 were formed. The electrolytic solution used was prepared by diluting L-tartaric acid in ethylene glycol at a concentration of 5% and adjusting the pH to 7.0 ± 0.2 using ammonia. The substrate 101 is dipped in the solution, the + side of the constant current source is connected to the gate wiring on the substrate, the platinum electrode is connected to the − side, and a voltage is applied in a constant current state of 20 mA, and 150 V is applied.
Oxidation was continued until it reached. Furthermore, the oxidation was continued at a constant voltage of 150 V until the current became 0.1 mA or less. As a result, an aluminum oxide film having a thickness of 2000Å was obtained.

After that, impurities (phosphorus in this case) are self-alignedly injected into the island-shaped silicon film 103 by ion doping using the gate electrode portion (that is, the gate electrode and the anodic oxide film around it) as a mask. A low concentration impurity region (LDD) 109 was formed as shown in FIG.
The dose amount is 1 × 10 ^{13 to} 5 × 10 ¹⁴ atoms / cm ² , and the acceleration voltage is 10 to 90 kV. For example, the dose amount is 5 × 10.
^{It was 13} atoms / cm ² and the acceleration voltage was 80 kV. (Fig. 6
(B))

Then, a silicon oxide film 110 was deposited by the plasma CVD method. Here, the source gas is TEO
S and oxygen, or monosilane and nitrous oxide were used.
The optimum value of the thickness of the silicon oxide film 110 differs depending on the height of the gate electrode / wiring. For example, as in this embodiment, the height of the gate electrode / wiring is about 60 including the anodic oxide film.
In case of 00Å, 1/3 to 2 times of 2000Å
1.2 μm is preferable, and here, it is 6000 Å.
In this film forming process, it is required that the film thickness be uniform in the flat portion and that the step coverage be good. As a result, the thickness of the silicon oxide film on the side surface of the gate electrode / wiring is increased by the amount indicated by the dotted line in FIG. 6 (C). (Fig. 6 (C))

Next, anisotropic dry etching is performed by the known RIE method to obtain the silicon oxide film 1.
08 etching was performed. This etching was completed when the etching reached the gate insulating film 105. Regarding the end point of such etching, for example,
It is possible to control the gate insulating film 105 by making the etching rate smaller than that of the silicon oxide film 110. Through the above steps, the substantially triangular insulators (sidewalls) 111 and 112 remained on the side surfaces of the gate electrode / wiring.

After that, phosphorus was introduced again by the ion doping method. The dose amount in this case is shown in FIG.
It is preferable that the dose is 1 to 3 orders of magnitude larger than the dose in the step. In this embodiment, the dose is 2 × 10 ¹⁵ atoms / cm ^{2 which} is 40 times the dose of the first phosphorus doping. Acceleration voltage is 80kV
And As a result, a region (source / drain) 114 into which a high concentration of phosphorus was introduced was formed, and a low concentration region (LDD) 113 was left below the sidewall.
(Figure 6 (D))

Further, a KrF excimer laser (wavelength 248 nm, pulse width 20 nsec) was irradiated to activate the doped impurities. The energy density of the laser was 200 to 400 mJ / cm ² , preferably 250 to 300 mJ / cm ² . (Fig. 6 (E))

Finally, the interlayer insulator 115 is formed on the entire surface,
A silicon oxide film having a thickness of 5000 Å was formed by the CVD method. Then, contact holes are formed in the source / drain of the TFT, and the second-layer aluminum wiring / electrode 11 is formed.
6, 117 were formed. The thickness of the aluminum wiring was set to 4000 to 6000Å, which is almost the same as that of the gate electrode / wiring. Through the above steps, a TFT having an N-channel LDD was completed. To activate the impurity region,
Further, hydrogen annealing may be performed at 200 to 400 ° C. Since the step of the second layer wiring 117 over the gate wiring 106 is gentle due to the presence of the sidewall 112, the thickness of the second layer wiring is almost the same as that of the gate electrode / wiring. Regardless, almost no breaks were observed. (Fig. 6 (F))

The following is a step of activating the doping impurities by laser irradiation in FIG. 6E among the above steps. Next, an outline of the configuration of the substrate to be processed in this embodiment will be described. FIG. 7 shows an outline of the cross section of the substrate processed in this example. A peripheral drive circuit area and a pixel circuit area are provided on the substrate, and the peripheral drive circuit is composed of NMOS and PMOS TFTs.
The pixel circuit is composed of a PMOS TFT.
A pixel electrode is provided in the TFT of the pixel circuit. (Figure 7)

FIG. 3 shows a state of the substrate to be processed in this embodiment as seen from above. As is apparent from FIG. 6E, in the steps described below, the interlayer insulator, the second layer wiring, and the like are not formed. As shown in FIG. 3A, the substrate 31
Scan drivers 32 and 33, column drivers 34 and 35, and an active matrix circuit 36 are formed thereon. Also in this embodiment, the laser beam 37 is large enough to irradiate the entire column drivers 34 and 35, for example, a width of 10 mm and a length of 300 m.
It is a rectangle of m.

First, as shown in FIG. 3B, the substrate was moved so that the scan driver 32 was irradiated with laser light. At this stage, the substrate is not irradiated with laser light. Then, the laser beam was irradiated without substantially moving the laser beam and the substrate. Laser light irradiation was performed in the atmosphere, and the substrate temperature was 200 ° C. The laser is a KrF excimer laser (wavelength 248n
m) was used. The oscillation frequency of the laser was 10 Hz, the energy density of the laser light was 300 mJ / cm ² , and the pulse of the laser light was 10 shots. When the irradiation of laser light for the required number of shots was completed, the irradiation of laser light was stopped. (Fig. 3 (B))

After that, the substrate is moved, and the scan driver 33 is set so as to be irradiated with the laser beam, and again,
Laser irradiation was performed without moving the substrate and the laser beam. In this case as well, under the same conditions as above, 1
A laser beam of 0 shot was irradiated. When the required number of shots of laser light was emitted, the laser light irradiation was stopped.
(FIG. 3C) After that, the substrate was rotated ¼. In FIG. 3D, a dotted square 38 is the position of the first substrate. (Fig. 3
(D))

After that, as shown in FIG. 3E, the substrate was moved so that the column driver 34 was irradiated with laser light. Then, the laser beam was irradiated without substantially moving the laser beam and the substrate. The irradiation conditions at this time are the same as above, and the pulse of laser light is 10
It was a shot. When the irradiation of laser light for the required number of shots was completed, the irradiation of laser light was stopped. (Fig. 3
(E))

Next, the position to be irradiated with the laser beam was shifted downward, and the substrate was moved to a position where the upper end of the active matrix region 36 (and the scan drivers 32 and 33) was hit by the laser beam 37. Then, the substrate was moved while irradiating the laser beam. For example, the oscillation frequency of the laser is 10 Hz, the energy density of the laser light is 250 mJ / cm ² , and the scanning speed of the laser light is 10
mm / s. As a result, the laser beam 25 is 1 m
It will shift by m. Since the width of the beam is 10 mm, about 10 shots of laser light will be applied to one location. (Fig. 3 (F))

In this way, the laser was scanned up to the lower end of the active matrix circuit 36, and the active matrix region 36 was irradiated with laser light. When irradiation is completed up to the lower edge of the active matrix,
Laser irradiation was stopped. Then, as shown in FIG. 3G, the substrate was moved so that the column driver 35 was irradiated with the laser light. Then, without substantially moving the laser beam and the substrate, the column driver 3
5 was irradiated with a laser beam. Laser oscillation frequency is 1
0 Hz, laser beam energy density is 300 mJ / c
The pulse of m ² and the laser beam was 10 shots. When the irradiation of laser light for the required number of shots was completed, the irradiation of laser light was stopped. (Fig. 3 (G))

In this embodiment, the column drivers 34 and 3 are used.
In 5, the laser beams did not overlap at all. On the other hand, in the scan driver, the laser beams were not overlapped in the laser light irradiation step shown in FIGS. 3B and 3C, but the laser beams of the active matrix circuit were overlapped. However, in comparison with the column driver, the scan driver has less restrictions on variations in characteristics, and the energy of laser light irradiation to the active matrix circuit is smaller than the energy of initial laser irradiation. There was no effect.

[0048]

According to the laser light irradiation technique of the present invention,
It was possible to improve the characteristics of the semiconductor circuit as a whole while maintaining mass productivity. INDUSTRIAL APPLICABILITY The present invention can be applied to all laser processing processes used in the process of semiconductor devices. In particular, when a TFT is taken as a semiconductor device, in order to improve the uniformity of the threshold voltage of the TFT, the first and second embodiments are used. It is very effective when used in the step of laser irradiation of the polycrystalline silicon film as described in the above. Further, in the sense that the field effect mobility of the TFT or the uniformity of the on-current is increased, the present invention is used in the step of activating the impurity element of the source / drain, in addition to the steps described above, as in Example 3. It is effective. As described above, the present invention is considered to be industrially useful.

[Brief description of drawings]

FIG. 1 shows a laser processing method according to an embodiment. (See Example 1)

FIG. 2 shows a laser processing method according to an embodiment. (See Example 2)

FIG. 3 shows a laser processing method according to an embodiment. (See Example 3)

FIG. 4 shows a conceptual diagram of a laser annealing apparatus used in Examples.

FIG. 5 shows a conceptual diagram of an optical system of a laser annealing apparatus used in Examples.

FIG. 6 shows an outline of a manufacturing process of a TFT element of an example. (See Example 3)

FIG. 7 shows a cross-sectional view of a TFT circuit. (Example 3
reference)

[Explanation of symbols]

11, 21, 31 Substrate 12, 22, 32, 33 Scan driver 13, 23, 34, 35 Column driver 14, 24, 36 Active matrix circuit region 15, 25, 37 Laser beam spot (linear laser beam) 26 , 38 shows the position of the substrate before rotation.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical indication location H01L 29/786 21/336 9056-4M H01L 29/78 311 A

Claims (5)

[Claims] 1. A line to a substrate having at least a first and a second semiconductor integrated circuit region (where the first circuit region is smaller than the second circuit region) or a region to be the circuit region. In the laser processing method of irradiating a pulsed laser beam, the beam size of the laser beam is larger than that of the first circuit region, and the laser beam is substantially irradiated during the laser beam irradiation. A first step of irradiating the entire first circuit region with laser light without moving, and after the first step, without irradiating laser light, a position to be irradiated with laser light A laser processing method for a semiconductor device, comprising: a second step of separating from the circuit area; and a third step of irradiating the second circuit area with laser light while scanning the laser light. 2. A line to a substrate having at least a first and a second semiconductor integrated circuit region (where the first circuit region is smaller than the second circuit region) or a region to be the circuit region. In the laser processing method of irradiating a pulsed laser beam, the substantial beam size of the laser beam is larger than that of the first circuit region, and the laser beam is scanned onto the second circuit region while scanning the laser beam. The first step of irradiating the laser beam, the second step of irradiating the laser beam after the first step, and the second step of moving the position to be irradiated with the laser beam to the first circuit region, and irradiating the laser beam of And a third step of irradiating the entire first circuit region with the laser light without substantially moving the laser light while performing the laser treatment. 3. The substrate according to claim 1, wherein after the third step, the substrate is rotated by (n / 2 + 1/4) (n is a natural number).
And a fourth step of performing a laser processing method for a semiconductor device. 4. A line to a substrate having at least a first and a second semiconductor integrated circuit region (where the first circuit region is smaller than the second circuit region) or a region to be the circuit region. In the laser processing method of irradiating a pulsed laser beam, the substantial beam size of the laser beam is larger than that of the first circuit region, and the laser beam is scanned onto the second circuit region while scanning the laser beam. The first step of irradiating the substrate, and (n / 2 + 1/4) rotation of the substrate (n / 2 + 1/4) after the first step.
Is a natural number), a third step of moving the position to be irradiated with laser light to the first circuit region without being irradiated with laser light after the second step, and laser light A fourth step of irradiating the entire first circuit region with the laser light without substantially moving the laser light during the irradiation, and a laser processing method for a semiconductor device. 5. The laser processing method for a semiconductor device according to claim 1, wherein a column driver is included in the first circuit region.