JPH1012950A - Pulse gas laser oscillator, laser annealer, manufacture of semiconductor device, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the oscillation pulse width of a laser beam by connecting a plurality of stages of peaking capacitors in parallel, with respect to a main discharge electrode via reactors having different inductance values. SOLUTION: A charge resistor 2, a high-voltage switching element 3, a main capacitor 4, a charge reactor 5, a floating impedance 6 and a main electrode 10 are installed to a high-voltage power supply 1. In addition, peaking capacitors 7a-7c and reactors 8a-8c having different inductance values are provided, and a preionization electrode pair 9 is provided between the peaking capacitor 7a and the reactor 8a. When the high-voltage switching element 3 is conducted in a state that the main capacitor 4 is charged, the gap of the preionization electrode pair 9 is conducted. Electric charges charged in the main capacitor 4 sequentially shift to the peaking capacitors 7a-7c, thus igniting a main discharge electrode pair 10. Thus, the oscillation pulse width of a laser beam is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pulse gas laser oscillation device, a laser annealing device, a method for manufacturing a semiconductor device, and a semiconductor device.

[0002]

2. Description of the Related Art In recent years, research on lowering the temperature in the manufacturing process of liquid crystal display elements and semiconductors has been actively pursued. As one of the techniques, there is a method in which a thermal annealing treatment is performed to improve the film quality of a thin film, for example, to crystallize an amorphous substance or to increase the particle diameter of a crystalline substance. Since the annealing process can reach a high temperature of about 600 ° C. or more, a substrate material having a high melting point such as an expensive quartz substrate is required.

However, as a specific method of performing the annealing treatment, there is a method using an excimer laser. The annealing treatment in a low-temperature process of about 450 ° C. using an excimer laser is a method of irradiating a substrate with a laser beam, instantaneously melting and solidifying the material, thereby crystallizing the material.

An excimer laser ignites and oscillates a uniform discharge in a high-pressure gas of about 2 to 4 atm containing a halogen gas, which is a negative gas. Half width: 10 [ns] to 3
It is about 0 [nS]. In the case of a special spiker / sustainer circuit or a large-sized X-ray preionization device, 200 [nS]
Some can realize a laser pulse waveform having a half-value width of about half.

[0005]

However, in an annealing process for manufacturing a semiconductor, it is required that the shape and pulse width of a laser pulse waveform to be irradiated cannot be realized by a conventional excimer laser depending on the process conditions. is there.

FIG. 17 shows an equivalent circuit of a laser oscillation device used for the conventional annealing process.
1 is a high voltage power supply, 2 is a charging resistor, 3 is a high voltage switching element such as a thyratron, 4 is a main capacitor,
5 is a charging reactor represented by a coil or the like, 6 is a floating inductance, 7 is a peaking capacitor, 8 is a reactor connected in series to the peaking capacitor 7,
Reference numeral 9 denotes a preionized electrode pair, and 10 denotes a main discharge electrode pair.

2-4 containing a halogen gas which is a negative gas
The floating inductance 6, the peaking capacitor 7, the reactor 8, the preionization electrode pair 9, and the main discharge electrode pair 10 are arranged in a gas chamber (not shown) filled with a high-pressure gas of about the atmospheric pressure.

The high voltage power supply 1 generates, for example, 30 [k].
[V], the high-voltage switching element 3 is instantaneously turned on while the main capacitor 4 is charged, and the potential difference causes the gap of the preionization electrode pair 9 to become conductive due to dielectric breakdown, so that the main capacitor 4 is charged. The charged electric charge moves to the peaking capacitor 7.

At this time, the pre-ionization discharge is ignited in the gap between the pre-ionization electrode pairs 9, and when the charging voltage of the peaking capacitor 7 exceeds the discharge starting voltage between the main discharge electrode pairs 10, the main discharge is ignited. Then, laser light is oscillated.

FIG. 18A shows a waveform of a discharge current flowing between the main discharge electrode pair 10 after the high voltage switching element 3 is turned on, and FIG. 18B shows a pulsed laser beam actually oscillated. The laser light has two peaks as shown in the figure, and here, the half width of the larger first peak is 20 [ns].

However, in the annealing treatment for expanding the crystal grain size, it is better that the time from melting to solidification is long, and therefore, it is required to increase the pulse width of the laser beam. . At that time, in order to ensure uniform heating of a large-area semiconductor substrate used in a liquid crystal display device, laser light irradiation is repeated at a high frequency while heating the semiconductor substrate by scanning with the laser light. Required.

However, the half-width of the pulse waveform of the laser beam obtained by this type of laser oscillation device is about 10 [nS] to 30 [nS] as described above, and there is no one that can sufficiently respond to the demand. Was.

Here, the value of the reactor 8 is reduced to a general value of 15.
From [nH] or less, it is conceivable to delay the rise of the discharge current and lengthen the pulse waveform of the laser beam by increasing the pulse width. However, this will reduce the oscillation efficiency and is not practical.

Further, the above-mentioned spiker / sustainer circuit is complicated and has the disadvantage that two switching elements must be used. Further, a large-sized apparatus for X-ray preionization is expensive and requires a large installation area. Because of the drawbacks such as the fact that the number of repetitions is limited, there is a strong demand for a laser oscillator that can increase the pulse width of laser light.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to enlarge the crystal grain size and to crystallize amorphous silicon into polysilicon having good electron mobility. A pulse gas laser oscillation device capable of performing oscillation with a sufficiently large pulse width of a laser beam, a laser annealing device using the oscillation device, a method for manufacturing a semiconductor device using the laser annealing device, and a method for manufacturing the semiconductor device using the laser annealing device. It is to provide a manufactured semiconductor device.

[0016]

The invention according to claim 1 is
A container for encapsulating the excitation gas, a pair of main discharge electrodes provided in the container so as to face each other, a plurality of pairs of preliminary ionization electrodes arranged for these main discharge electrodes, and a space between these preliminary ionization electrodes A charge / discharge circuit including a main capacitor for charging / discharging the supplied power, a power supply for supplying power to the charge / discharge circuit, and a pair of main discharge electrodes connected in parallel to the pair of main discharge electrodes for storing power from the main capacitor In a pulse gas laser oscillation device including a peaking capacitor, a reactor connected in series to the peaking capacitor, and an optical resonator that amplifies light generated at the main discharge electrode,
The peaking capacitor has a configuration in which a plurality of stages are connected in parallel to a main discharge electrode via the reactor having different inductance values.

With this configuration, a pulse current flows from each peaking capacitor to the preliminary ionization electrode with a time difference at the time of discharge firing depending on the inductance value of each reactor, and the pulse width and pulse interval of the pulsed laser light Can be made variable.

According to a second aspect of the present invention, in the first aspect of the invention, each capacitance of the main capacitor and the peaking capacitor has a configuration in which a plurality of stages are connected in parallel to the pair of main discharge electrodes. It is characterized in that the values and the inductance values of the reactors respectively connected to the peaking capacitors are set to control the aging change of the oscillation light intensity.

With this configuration, in addition to the operation of the first aspect of the present invention, a single laser oscillator can oscillate pulsed laser light having a variable pulse width and pulse interval.

According to a third aspect of the present invention, in the second aspect of the present invention, when the number of the peaking capacitors is three, C1, C2, and C3 are set in order from the one electrically closer to the power source, and these three peaking capacitors are used. Let L1, L2, L3 denote the reactors respectively connected in series to Cm, and let the main capacitor be Cm.
1 ≒ C2 ≒ C3 ”and“ Cm ≒ C1 + C2 + C3 ”, and the inductance values of these three reactors satisfy the relationship“ L1 <L2 <L3 ”.

With this configuration, in addition to the effect of the second aspect of the present invention, a pulse laser beam having a sufficiently long pulse width can be oscillated. According to a fourth aspect of the present invention, in the second aspect of the present invention, when the number of the peaking capacitors is two, C1 and C2 are set to be electrically close to the power supply and are connected in series to the two peaking capacitors. Let L1 and L2 denote reactors and the main capacitor Cm, respectively, the capacitance values of these peaking capacitors and the main capacitor satisfy the relationship of "CmmC1 + C2", and the capacitance values of these peaking capacitors are Each inductance value of these reactors is “2 (L1 · C1)
^1/2 <(L2 · C2) ^1/2 ”.

With this configuration, in addition to the effect of the second aspect of the invention, it is possible to oscillate pulse laser light having a variable pulse interval. According to a fifth aspect of the present invention, in the second aspect of the present invention, when the number of the peaking capacitors is two, C1 and C2 are set from the side electrically closer to the power supply, and are connected in series to these two peaking capacitors. Let L1 and L2 denote the reactors, Cm the main capacitor, and Ls the reactor connected in parallel with the saturable reactor on the electric path from C1 to C2. Of each capacitance is “Cm ≒
C1 + C2 ", and the capacitance values of these peaking capacitors and the inductance values of these reactors are" 2 (L1.C1) ^1/2 <((L
2 + Ls) .C2) ^1/2 ".

According to this structure, in addition to the function of the invention according to the second aspect, the pulse interval is maintained while maintaining the output of the laser beam without changing the circuit constant of the excitation circuit for exciting the excitation gas. A variable pulse laser beam can be oscillated.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the peaking condenser and the reactor are provided outside the container so as to be detachable.

With this configuration, in addition to the operation of the first aspect of the invention, the element constants of the peaking capacitor and the reactor connected to the peaking capacitor can be arbitrarily and easily changed. By changing the element constants, pulse laser light can be oscillated while easily obtaining a desired pulse width and pulse interval.

According to a seventh aspect of the present invention, there is provided a container for enclosing an excitation gas, a pair of main discharge electrodes provided to face each other in the container, and a plurality of pairs of main discharge electrodes arranged with respect to the main discharge electrodes. A pre-ionization electrode, a charge / discharge circuit including a main capacitor for charging / discharging electric power supplied between the pre-ionization electrodes,
A power supply for supplying power to the charging / discharging circuit, a peaking capacitor connected in parallel to the pair of main discharge electrodes for storing power from the main capacitor, a reactor connected in series to the peaking capacitor, A pulse gas laser oscillating unit including an optical resonator that amplifies light generated at the main discharge electrode, a chamber in which the object to be processed is stored, and pulse light output from the pulse gas laser emitting unit to the object to be processed. In the laser annealing apparatus having irradiation means for irradiating, the peaking capacitor has a configuration in which a plurality of stages are connected in parallel to the main discharge electrode via the reactors having different inductance values.

With this configuration, a single laser oscillator can oscillate pulsed laser light having a variable pulse width and pulse interval. Anneal processing can be performed.

The invention according to claim 8 is the invention according to claim 7, wherein each capacitance of the main capacitor and the peaking capacitor has a configuration in which a plurality of stages are connected in parallel to the pair of main discharge electrodes. It is characterized in that the values and the inductance values of the reactors respectively connected to the peaking capacitors are set to control the aging change of the oscillation light intensity.

With such a configuration, in addition to the effect of the invention according to the seventh aspect, a single laser oscillator oscillates pulsed laser light having a variable pulse width and a variable pulse interval. Anneal processing can be performed.

According to a ninth aspect of the present invention, in the invention according to the eighth aspect, when the number of the peaking capacitors is three, C1, C2, and C3 are set in order from the one electrically closer to the power source, and these three peaking capacitors are used. Let L1, L2, L3 denote the reactors respectively connected in series to Cm, and let the main capacitor be Cm.
1 ≒ C2 ≒ C3 ”and“ Cm ≒ C1 + C2 + C3 ”, and the inductance values of these three reactors satisfy the relationship“ L1 <L2 <L3 ”.

With such a configuration, in addition to the effect of the invention according to the eighth aspect, it is possible to oscillate pulse laser light having a sufficiently long pulse width and to perform a good annealing process on the object to be processed.

According to a tenth aspect of the present invention, in the eighth aspect of the present invention, when the number of the peaking capacitors is two, C1 and C2 are placed from the side electrically closer to the power source, and these two peaking capacitors are respectively provided. When the reactors connected in series are denoted by L1 and L2 and the main capacitor Cm, the capacitance values of the peaking capacitor and the main capacitor are expressed as “Cm ≒ C1 +
C2 ", and the respective capacitance values of these peaking capacitors and the respective inductance values of these reactors are" 2 (L1.C1) ^1/2 <(L2.C2
) ^1/2 ”.

With such a configuration, in addition to the operation of the eighth aspect of the present invention, it is possible to oscillate pulse laser light having a variable pulse interval and perform a good annealing process on the object.

According to an eleventh aspect of the present invention, in the invention according to the eighth aspect, when the number of the peaking capacitors is two, C1 and C2 are placed from the side electrically closer to the power supply, and these two peaking capacitors are respectively provided. The reactors connected in series are denoted by L1 and L2, the main capacitor is denoted by Cm, and the reactor connected in parallel with the saturable reactor on the electrical path from C1 to C2 is denoted by Ls.
In particular, the capacitance values of these peaking capacitors and the main capacitor satisfy the relationship of “Cm ≒ C1 + C2”, and the capacitance values of these peaking capacitors and the inductance values of these reactors are “2 (L1 · C1 ) ^1/2 <((L2 + Ls) C2
) ^1/2 ”.

According to this structure, in addition to the function of the invention according to claim 8, the circuit constant of the excitation circuit for exciting the excitation gas is not changed, and the pulse interval is maintained while maintaining the output of the laser light. By oscillating a variable pulse laser beam, a favorable annealing process can be performed on the object.

A twelfth aspect of the present invention is characterized in that, in the seventh aspect of the present invention, the peaking condenser and the reactor are provided outside the container so as to be detachable.

With this configuration, in addition to the effect of the invention according to claim 7, the element constants of the peaking capacitor and the reactor connected to the peaking capacitor can be arbitrarily and easily changed. By changing the element constants described above, it is possible to easily obtain a desired pulse width and pulse interval, oscillate pulse laser light, and perform a favorable annealing process on the object to be processed.

According to a thirteenth aspect of the present invention, there is provided a method of manufacturing a semiconductor device having an annealing step of an amorphous semiconductor substrate using pulsed laser light, wherein a half-value width of a part of the amorphous semiconductor substrate is 50 [nS] or more. Annealing the amorphous semiconductor substrate by repeatedly scanning the pulsed laser light with respect to the amorphous semiconductor substrate while repeatedly irradiating light with the pulsed laser light having the above pulse width.

According to such a method, when the amorphous semiconductor is polycrystallized, the crystal grain size can be set to an optimum value, so that the electron mobility of the semiconductor substrate can be increased. .

According to a fourteenth aspect of the present invention, the amorphous semiconductor substrate is irradiated with the pulsed laser beam while repeatedly irradiating a portion of the amorphous semiconductor substrate with a pulsed laser beam having a pulse width of 50 [ns] or more. It is characterized in that a polycrystalline semiconductor substrate which has been annealed by scanning relative to the substrate is used.

When a polycrystalline semiconductor substrate having such a structure is used, the crystal grain size can be set to an optimum value when the amorphous semiconductor is polycrystallized, so that the electron mobility can be increased. A semiconductor device with a high operation speed can be obtained.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an equivalent circuit of the laser oscillation device, which is basically the same as that shown in FIG. 17, so that the same portions are denoted by the same reference numerals and description thereof will be omitted.

Thus, instead of the peaking capacitor 7 and the reactor 8 of FIG. 17, n stages (n: an integer of 2 or more), for example, a three-stage peaking capacitor 7a,
7b, 7c and reactors 8a, 8b, 8c connected to these capacitors are provided, and the preliminary ionization electrode pair 9 is arranged so as to be connected in series with the peaking capacitor 7a and the reactor 8a.

The main discharge electrode pair 10 and the preliminary ionization electrode pair 9 are provided in a gas chamber (not shown) in which a gas laser medium is sealed. Here, the capacitance Cm of the main capacitor 4 and the peaking capacitors 7a to
7c and the respective capacitances C1, C2 and C3 are expressed as "C1 ≒ C2 ≒ C
3 ”and“ Cm ≒ C1 + C2 + C3 ”, and the values of the reactors 8a to 8c are L1 to L
If it is set to 3, it is set so that “L1 <L2 <L3”.

In the circuit configuration as described above, when a current flows through a loop including the high-voltage power supply 1, the charging resistor 2, the main capacitor 4, and the charging reactor 5, the high-voltage power supply 1 is generated. For example, a high voltage of 30 [kV] is charged in the main capacitor 4.

When the high-voltage switching element 3 is momentarily turned on by the trigger pulse while the main capacitor 4 is charged, the main capacitor 4, the high-voltage switching element 3, the peaking capacitors 7a to 7c, and the reactors 8a to 8c In the loop circuit formed by the preliminary ionization electrode pair 9 and the stray inductance 6, the potential difference causes the gap of the preliminary ionization electrode pair 9 to conduct due to insulation breakdown, and the electric charge charged in the main capacitor 4 to the peaking capacitors 7a to 7a. Move to 7c.

Here, in the gap between the preionizing electrode pair 9, the preionizing discharge is ignited, and the peaking capacitor 7
When the charging voltages a to 7c exceed the discharge starting voltage between the main discharge electrode pairs 10, the main discharge is ignited and laser light is oscillated.

At this time, as described above, the reactor 8a
Since the values of .about.8c are set to satisfy "L1 <L2 <L3", the current from the peaking capacitor 7a connected in series to the reactor 8a having the smallest value first flows through the main discharge electrode pair 10. Subsequently, for the same reason, the current from the peaking capacitor 7b and then the current from the peaking capacitor 7c flow to the main discharge electrode pair 10, respectively.

FIG. 2 shows that the values of the reactors 8a to 8c are L1
= 10 [nH], L2 = 40 [nH], L3 = 90 [n]
H] and the capacity of the main capacitor 4 is set to 120 [n].
F], and shows the waveforms of the discharge currents Ia to Ic from the peaking capacitors 7a to 7c when the capacities of the peaking capacitors 7a to 7c are equally set to 40 [nF].

FIG. 3 shows these discharge currents Ia to Ic.
The waveform of the voltage applied between the main discharge electrode pair 10 is shown by a solid line V, and the time until the polarity is reversed is 100.
[NS] or more. From the viewpoint of maintaining a stable discharge state, it is necessary to complete the energy injection from the peaking capacitors 7a to 7c between the main discharge electrode pairs 10 before the polarity is reversed.

Incidentally, the broken line Vp in FIG.
5 shows the waveform of the voltage applied between the main discharge electrode pair 10 in the case of the conventional circuit of FIG.

FIG. 4A shows the waveform of the discharge current in the entire peaking capacitors 7a to 7c, and FIG.
The waveform of the light intensity of the laser light oscillated in the above manner is shown, and the half width of the pulse waveform of the laser light is 100 [ns].
It can be seen that the length is very long.

The values of the reactors 8a to 8c are represented by L
1 = 15 [nH], L2 = 30 [nH], L3 = 45
FIG. 5A shows the waveform of the discharge current in the entire peaking capacitors 7a to 7c when [nH] is set and the capacities of the main capacitor 4 and the peaking capacitors 7a to 7c are set in the same manner as described above. , Actually the main discharge electrode pair 10
FIG. 5 (b) shows the waveform of the light intensity of the laser light oscillated by. Here also, the half width of the pulse waveform of the laser light is 50
It is as long as [nS].

Incidentally, the broken line in FIG.
7, the value of the reactor 8 is set to 30 [nH].
This shows the light intensity waveform of the laser light when the value is set to be large. It can be seen that the output energy, which is the integral value of the waveform, is significantly reduced because the rise of the discharge current is delayed.

In the configuration shown in FIG. 1, three peaking capacitors 7a to 7c are provided for the main capacitor 4, but the number of peaking capacitors is also two.
The number of peaking capacitors connected in parallel to the capacitance of the main capacitor 4, the capacitance of each peaking capacitor, and the value of the reactor connected in series with each peaking capacitor are variously combined. Pulse light having an arbitrary waveform shape can be obtained.

At this point, as described above, the peaking capacitors 7a to 7c and the reactors 8a to 8c are provided outside the gas chamber separately from the preionization electrode pair 9 and the main discharge electrode pair 10, so that these can be arbitrarily selected. It can be easily realized by attaching and detaching it.

In FIG. 1, the preliminary ionization electrode pair 9 is arranged in series with the peaking capacitor 7a connected to the reactor 8a having the smallest value. May be connected in series with the floating inductance 6 as shown by the preliminary ionization electrode pair 9 ′ in FIG. 6 on the electric circuit, or the preliminary ionization electrode pair 9 ″ in FIG. , The peaking capacitors 7a to 7c and the reactor 8
The same effect can be obtained even when the connection is made in series with all of a to 8c.

Since the rise time of the charging voltage of the peaking capacitors 7a to 7c before the main discharge starts at the main discharge electrode pair 10 is different, the higher the main discharge starting voltage is, the more the charging voltage of the peaking capacitors 7b and 7c is increased. 7a, and the laser oscillation efficiency increases.

Therefore, in the case of a XeCl excimer laser, Ar is used in place of 5 [%] to 20 [%] as a substitute for Ne with respect to a conventional gas mixture of Xe, HCl and Ne. It will be more effective.

FIG. 8 shows the laser oscillation device 1 shown in FIG.
1 illustrates a configuration example of a laser annealing apparatus including the laser annealing apparatus of FIG. In the figure, reference numeral 12 denotes an excimer laser tube in the laser oscillation device 11, and a laser beam oscillated by the laser oscillation device 11 is reflected by a mirror 14 and attenuated by a beam attenuator 15 with an appropriate attenuation rate. The laser beam 17 is converted into a linear laser beam 16 and irradiated on a semiconductor substrate 20 placed on a tray 21 in the annealing chamber 19 via a quartz window 18 provided in the annealing chamber 19. However, tray 21
Is two-dimensionally scanned by the tray driving device 22,
By this scanning, the laser beam 17 can be applied to the entire surface of the semiconductor substrate 20.

In the laser annealing apparatus having the above configuration, the half-width of the light intensity waveform shown in FIG.
[NS] laser light is oscillated by the laser oscillation device 11,
FIG. 9A shows a characteristic example of the crystal grain size obtained when the energy density is changed by adjusting the laser output. In FIG. 9A, when the solid line α has a half width of 50 [nS], the broken line β
Is the same as the conventional case where the half width is 20 [nS]. By increasing the half width, the same annealing effect as the conventional one can be obtained even at a low energy. In particular, when the half width is 50 [nS], the energy density is high. It can be seen that a target value of the crystal grain size of 0.4 [μm] can be obtained at 350 [mJ / cm ² ].

FIG. 9B shows that the energy density is 35%.
This shows an example of the characteristic of the crystal grain size obtained when the light intensity waveform is fixed at 0 [mJ / cm ² ] and the half width of the light intensity waveform is changed. As described above, the target value of the crystal grain size of 0.4 [μm] is obtained with the half value width of 50 [nS], and the crystal grain size can be further expanded by naturally setting the half value width to be longer. You can see that there is.

Next, a case where a thin film transistor is actually manufactured by the above-described laser annealing apparatus will be described. FIG. 10 shows that after an undercoat layer 32 made of SiOx or SiNx is formed on a glass substrate 31 by a plasma CVD method, amorphous silicon 33 (a
-Si) is formed by, for example, 50 [nm] by a plasma CVD method. Here, the size of the substrate is, for example, 300 [mm] × 400 [mm].

Here, it is assumed that an annealing process is performed by the laser annealing apparatus as shown by an arrow L in the figure. Excimer laser irradiation size is 200 [mm] x
A linear beam of 0.4 [mm] was used, the energy density on the substrate was 350 [mJ / cm ² ], and the overlap ratio was 90.
Set to [%]. The repetition frequency of the laser is 200 [Hz], and the tray 21 on which the substrate is placed is scanned and moved at 0.8 [mm / S] by the tray driving device 22.
The entire surface of the substrate is annealed by the excimer laser.

In this way, the annealing process is performed with a-Si 33
To make the average crystal grain size 0.4 [μm] or more, thereby obtaining an average electron mobility of 100 [cm ² / V ·
S], and a-Si can be further dehydrogenated and reformed into polysilicon. Fig. 1
An active matrix panel as shown in FIG.

That is, FIG. 11 shows a circuit structure of an active matrix panel in which a driving section and a pixel section are formed on the same substrate. In the figure, 40 is a transparent insulating substrate of the same material as the glass substrate 31 on which the undercoat layer 32 is formed,
Reference numeral 41 denotes a channel region of a P-type TFT (thin film transistor), reference numerals 42 and 43 denote channel regions of an N-type TFT, and these channel regions 41 to 43 correspond to the a-Si of FIG.
33, which has been modified into polysilicon by the above-described annealing process.

Further, 44 to 46 are gate insulating films,
49 is a gate electrode, 51 and 52 are sources of a P-type TFT.
.. Are drain regions, 53 to 56 are source / drain regions of an N-type TFT, 59 is an interlayer insulating film, 60, 60,.
61 is a pixel electrode made of a transparent conductive film, 62 is a P-type TFT of the completed driver circuit portion, and 63 is an N-type TF of the same.
T and 64 are pixel TFTs of the completed pixel matrix portion.

Such a circuit structure is formed by a normal photolithography process. In particular, since the electron mobility of each of the channel regions 41 to 43 formed by the annealing process of the present invention is high, the drive voltage is set low. And can be sufficiently practical.

FIG. 12 illustrates a partial configuration of a liquid crystal display panel formed using the active matrix panel formed as described above. The entire surface including the pixel TFT 64 and the pixel electrode 61 is covered with an insulating film 65. A liquid crystal material 66 is sealed between the counter electrode 67 including the transparent conductive film layer and the transparent substrate 68 thereon. The spacer,
A color filter, a black matrix, and the like are not shown.

With this structure, the pixel matrix section is integrated with the driver circuit section as shown in FIG. 11, so that the thickness of the entire liquid crystal display panel can be suppressed and the driver Since circuits can be formed at a high density, the pixel pitch can be suppressed, which can greatly contribute to higher definition of a screen. Further, since high electron mobility can be obtained, high-speed operation can be realized even with the TFT of the driving portion, and the speed of screen display can be increased.

In the above embodiment, the case where the annealing process according to the present invention is applied to the channel region of the TFT has been exemplified. However, the present invention is not limited to this. Needless to say, the present invention can be applied to various parts.

For example, in the embodiments of the present invention, a TFT has been described as an example of a semiconductor device.
Of course, it may be used for other types of semiconductor devices typified by AM, DRAM and the like. This is because the purpose of the present invention is to satisfactorily polymorph amorphous silicon.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 13 shows an equivalent circuit of the laser oscillation device, which is basically the same as that shown in FIG. 1, and therefore, the same parts are denoted by the same reference numerals and description thereof will be omitted.

In place of the peaking capacitors 7a to 7c and the reactors 8a to 8b shown in FIG. 1, two-stage peaking capacitors 7a and 7b and reactors 8a and 8b connected to these capacitors are provided. The pair 9 is arranged so as to be connected in series with the peaking capacitor 7a and the reactor 8a.

The main discharge electrode pair 10 and the preliminary ionization electrode pair 9 are provided in a gas chamber (not shown) in which a gas laser medium is sealed. Here, the capacitance Cm of the main capacitor 4 and the peaking capacitors 7a,
The capacitances C1 and C2 of the reactor 7b are set so as to satisfy the relationship of “Cm ≒ C1 + C2”, and the inductance values L1 and L2 of the reactors 8a and 8b are set to “2 (L1 · C1)”.
^1/2 <(L2 · C2) ^1/2 ”.

In the circuit configuration as described above, when a current flows through a loop including the high-voltage power supply 1, the charging resistor 2, the main capacitor 4, and the charging reactor 5, the high-voltage power supply 1 is generated. For example, a high voltage of 30 [kV] is charged in the main capacitor 4.

When the main capacitor 4 is charged and the high voltage switching element 3 is momentarily turned on by a trigger pulse, the main capacitor 4, the high voltage switching element 3, the peaking capacitors 7a and 7b, and the reactors 8a and 8b In the loop circuit formed by the preliminary ionization electrode pair 9 and the stray inductance 6, the potential difference causes the gap of the preliminary ionization electrode pair 9 to conduct due to insulation breakdown, and the electric charge charged in the main capacitor 4 is reduced to the peaking capacitors 7a, 7b, the voltage between the main discharge electrode pairs 10 increases. Excitation discharge occurs between the main discharge electrode pairs 10 when the voltage between the main discharge electrode pairs 10 exceeds the discharge breakdown voltage.

When this excitation discharge occurs, the main discharge electrode pair 10
The resistance value between them is about 0.8 [Ω]. At this time, as described above, since “C1 <C2” and “L1 <L2” are set, immediately after the excitation discharge, the electric charge stored in the peaking capacitor 7a firstly becomes the peaking capacitor 7a.
a, a reactor 8a, a preliminary ionization electrode pair 9, and a main discharge electrode pair 10 are used as excitation energy in a loop circuit, and the excitation discharge causes the main discharge electrode pair 10 to emit a first laser beam. .

The electric charge stored in the peaking capacitor 7b is transferred to the peaking capacitor 7b and the reactor 8
Since the reactor 8b has a larger value than the reactor 8a in the loop circuit formed by b and the main discharge electrode pair 10, the transition speed becomes slow. Therefore, the electric charge of the peaking capacitor 7b is hardly used for this first excitation.

When the electric charge stored in the peaking capacitor 7a is used for excitation, the potential drops, and the electric charge stored in the peaking capacitor 7b is replaced with the electric charge stored in the peaking capacitor 7b delayed by the excitation discharge. It moves in a loop circuit formed by the ionizing electrode pair 9, the reactor 8a, and the peaking capacitor 7a, and is charged in the peaking capacitor 7a.

In this way, the electric charge stored in the peaking capacitor 7a increases again, and when the potential rises, in the loop circuit formed by the peaking capacitor 7a, the reactor 8a, the preionization electrode pair 9, and the main discharge electrode pair 10, The second laser beam is emitted from the main discharge electrode pair 10 by using the excitation energy.

Similarly, when the potential of the peaking capacitor 7a drops, the electric charge moves from the peaking capacitor 7b, the potential rises again, and the third laser light is emitted. However, when the peaking capacitor 7b emits a small amount of electric charge when the second laser light is emitted and the gas cannot be excited to an oscillation state, for example, about 1 [MW / cm ³ ], which is required by an excimer laser, the third laser light Is not emitted.

FIG. 14A shows a voltage waveform between the main discharge electrode pairs 10 during the above operation, and FIG. 14B shows a light intensity waveform of laser light oscillated from the main discharge electrode pair 10. is there. The time during which the voltage rises after discharging is proportional to the following equation sinh (SQR (1 / (L1 · C1))) (1), which is obtained from the capacitance C1 of the peaking capacitor 7a and the value L1 of the reactor 8a. The charging time from 7b to the peaking capacitor 7a is proportional to the following equation: sinh (SQR (1 / (L1 + L2). (C1 + C2))) (2)

The laser beam is emitted from the voltage waveform shown in FIG. In order to obtain the second pulsed light, before the time when the potential at the peaking capacitor 7a becomes 0 [V] from the above equation (1), the electric charge is discharged from the peaking capacitor 7b based on the above equation (2). Need to be implanted and the energy at that time is 1
Since the value must be equal to or more than [MW / cm ³ ], the value of each element is set as such.

As described above, by continuously oscillating two pulses having an interval of time ΔT, when this laser oscillation measure is applied to a laser annealing apparatus, an object to be annealed evaporates in an annealing process of semiconductor manufacturing. It is possible to obtain good results such as crystallization of the non-crystalline substance and improvement of the crystal grain size without causing such problems.

In the circuit configuration shown in FIG. 13, the interval between successive laser light pulses is determined by the circuit constant of the excitation circuit, and the laser output also changes because the discharge voltage waveform changes. Becomes Therefore,
An example in which the interval between successive laser light pulses can be set without changing the discharge circuit constant will be described as a modification of the second embodiment.

FIG. 15 shows the circuit configuration, which is basically the same as that shown in FIG. 13. Therefore, the same portions are denoted by the same reference numerals and description thereof is omitted. Thus, instead of the position of the stray inductance 6 in FIG. 13, one side of the preliminary ionization electrode pair 9 not connected to the reactor 8a and the peaking capacitor 7 of the reactor 8b are used.
The reactor 6a and the saturable realtor 6b are connected in parallel between b and the unconnected end.

Here, the capacitance Cm of the main capacitor 4 and the capacitances C1 and C2 of the peaking capacitors 7a and 7b are set so as to satisfy the relationship of “Cm ≒ C1 + C2”, and the inductance values L1 of the reactors 8a and 8b are set. , L
2. Each inductance value Ls of the reactor 6a is set to "2
(L1 · C1) ^1/2 <((L2 + Ls) · C2) ^1/2 ”
It is set so that Are set to be substantially equal to each other and “C1 <C2”.

Further, the values of reactors 8a and 8b are
1, L2 and the value of the reactor 6a as L4, "L1 <
L2 "," L1 = L4 ", and" L1 + L4 <L2 ".

In the circuit configuration as described above, current flows through a loop circuit composed of the high-voltage power supply 1, the charging resistor 2, the main capacitor 4, and the charging reactor 5,
The main capacitor 4 is charged with a high voltage of, for example, 30 [kV] generated by the high voltage power supply 1.

When the main capacitor 4 is charged and the high-voltage switching element 3 is momentarily turned on by a trigger pulse, the main capacitor 4, the high-voltage switching element 3, the peaking capacitors 7a and 7b, and the reactors 8a and 8b. , Preliminary ionization electrode pair 9 and reactor 6
In the loop circuit formed by a, the gap between the preionization electrode pair 9 is made conductive by the dielectric breakdown due to the potential difference, and the electric charge charged in the main capacitor 4 moves to the peaking capacitors 7a and 7b, and the main discharge electrode pair 10 The voltage between them rises. Excitation discharge occurs between the main discharge electrode pairs 10 when the voltage between the main discharge electrode pairs 10 exceeds the discharge breakdown voltage.

When this excitation discharge occurs, the main discharge electrode pair 10
The resistance value between them is about 0.8 [Ω]. At this time, as described above, since “C1 <C2” and “L1 <L2” are set, immediately after the excitation discharge, the electric charge stored in the peaking capacitor 7a firstly becomes the peaking capacitor 7a.
a, a reactor 8a, a preliminary ionization electrode pair 9, and a main discharge electrode pair 10 are used as excitation energy in a loop circuit, and the excitation discharge causes the main discharge electrode pair 10 to emit a first laser beam. .

The electric charge stored in the peaking capacitor 7b is transferred to the peaking capacitor 7b and the reactor 8
b, reactor 6a, and reactor 8b having a larger value than reactor 8a and reactor 6 equivalent to reactor 8a in a loop circuit formed by main discharge electrode pair 10.
Since there is a, the transition speed becomes slow. Therefore, the electric charge of the peaking capacitor 7b is hardly used for this first excitation.

When the electric charge stored in the peaking capacitor 7a is used for excitation, the potential drops. At this time, when the saturable real torque 6b saturates and the reactor at the time of saturation becomes sufficiently small to about 1/5 of the inductance 6a, the electric charge stored in the peaking capacitor 7b sharply decreases. Realtor 6b, Preionization electrode pair 9, Reactor 8
a and a looping circuit formed by the peaking capacitor 7a, and the peaking capacitor 7a is charged.

In this way, the electric charge stored in the peaking capacitor 7a increases again, and the potential rises. In the loop circuit formed by the peaking capacitor 7a, the reactor 8a, the preliminary ionization electrode pair 9, and the main discharge electrode pair 10, The second laser beam is emitted from the main discharge electrode pair 10 by using the excitation energy.

FIG. 16A shows a voltage waveform between the main discharge electrode pairs 10 during the above operation, and FIG. 16B shows a light intensity waveform of laser light oscillated from the main discharge electrode pair 10. is there. Like the reactor 6a, the peaking capacitors 7a and 7b, and the reactors 8a and 8b, the saturable realtor 6b is detachably provided outside the gas chamber in which the preliminary ionization electrode pair 9 and the main discharge electrode pair 10 are arranged. Therefore, the time interval ΔT between the continuously oscillated first laser light and second laser light can be arbitrarily set according to the operation timing of the saturable realtor 6b.

As described above, the time interval ΔT between laser pulses continuously oscillated can be arbitrarily set, so that when this laser oscillation apparatus is applied to a laser annealing apparatus, the time interval ΔT depends on the characteristics of the object to be annealed. Thus, a better annealing process can be performed.

For example, in the embodiments of the present invention, a TFT has been described as an example of a semiconductor device.
Of course, it may be used for other types of semiconductor devices such as a RAM and a DRAM. This is because the purpose of the present invention is to satisfactorily polymorph amorphous silicon.

Further, the present invention can also be used to form a thin film of metal such as copper provided on a semiconductor substrate while melting it while preventing evaporation. The present invention is not limited to the first and second embodiments, and it goes without saying that various modifications can be made without departing from the scope of the invention.

[0100]

According to the first aspect of the present invention, a pulse current is caused to flow between each peaking capacitor and the preliminary ionization electrode with a time difference at the time of discharge ignition by the inductance value of each reactor, and the pulse of the pulsed laser light The width and pulse interval can be made variable.

According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, a single laser oscillator can oscillate pulsed laser light having a variable pulse width and pulse interval.

According to the third aspect of the invention, in addition to the effect of the second aspect of the invention, it is possible to oscillate pulse laser light having a sufficiently long pulse width. According to the invention of claim 4, in addition to the effect of the invention of claim 2, it is possible to oscillate pulsed laser light having a variable pulse interval.

According to the fifth aspect of the present invention, in addition to the effect of the second aspect of the present invention, in addition to maintaining the output of the laser beam without changing the circuit constant of the excitation circuit for exciting the excitation gas, Pulse laser light with variable intervals can be oscillated.

According to the invention of claim 6, in addition to the effect of the invention of claim 1, the element constants of the peaking capacitor and the reactor connected to the peaking capacitor can be arbitrarily and easily changed. By changing these element constants, pulse laser light can be oscillated while easily obtaining a desired pulse width and pulse interval.

According to the seventh aspect of the present invention, a single laser oscillator can oscillate a pulsed laser beam having a variable pulse width and a variable pulse interval. , A good annealing process can be performed.

According to an eighth aspect of the present invention, in addition to the effect of the seventh aspect of the invention, a single laser oscillator oscillates pulsed laser light having a variable pulse width and a variable pulse interval. , A good annealing process can be performed.

According to the ninth aspect of the present invention, in addition to the effect of the eighth aspect of the present invention, it is possible to oscillate a pulse laser beam having a sufficiently long pulse width and perform a good annealing process on the object to be processed. it can.

According to the tenth aspect, in addition to the effect of the eighth aspect, a pulse laser beam having a variable pulse interval is oscillated to perform a favorable annealing process on the object. .

According to the eleventh aspect of the present invention, in addition to the effect of the eighth aspect, the pulse constant is maintained while maintaining the output of the laser light without changing the circuit constant of the excitation circuit for exciting the excitation gas. By oscillating pulse laser light with variable intervals, a good annealing process can be performed on the object.

According to the twelfth aspect, in addition to the effect of the seventh aspect, the element constants of the peaking capacitor and the reactor connected to the peaking capacitor can be arbitrarily and easily changed. By changing these element constants, it is possible to oscillate pulsed laser light while easily obtaining a desired pulse width and pulse interval, and to perform a good annealing process on the object to be processed.

According to the thirteenth aspect, when the amorphous semiconductor is polycrystallized, the crystal grain size can be set to an optimum value, so that the electron mobility of the semiconductor substrate can be increased. Becomes

According to the fourteenth aspect of the present invention, when the amorphous semiconductor is polycrystallized, the crystal grain size can be set to an optimum value. A high semiconductor device can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of a laser oscillation device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an operation according to the embodiment.

FIG. 3 is a diagram illustrating an operation according to the embodiment.

FIG. 4 is a diagram illustrating an operation according to the embodiment.

FIG. 5 is a diagram illustrating an operation according to the embodiment.

FIG. 6 is a diagram illustrating another circuit configuration according to the embodiment;

FIG. 7 is a diagram illustrating another circuit configuration according to the embodiment;

FIG. 8 is a diagram showing a functional configuration of the laser annealing apparatus according to the embodiment.

FIG. 9 is a view for explaining the operation of the laser annealing apparatus according to the embodiment.

FIG. 10 illustrates a manufacturing process of the thin film transistor according to the embodiment.

FIG. 11 illustrates a cross-sectional structure of an active matrix panel including the thin film transistors according to the embodiment.

FIG. 12 is a diagram illustrating a cross-sectional structure of a liquid crystal display panel including the thin film transistor according to the embodiment.

FIG. 13 is a diagram showing a circuit configuration of a laser oscillation device according to a second embodiment of the present invention.

FIG. 14 illustrates the operation of the circuit in FIG. 13;

FIG. 15 is a diagram showing a modification of the circuit configuration of the laser oscillation device according to the second embodiment of the present invention.

FIG. 16 illustrates the operation of the circuit in FIG. 15;

FIG. 17 is a diagram showing a circuit configuration of a general laser oscillation device.

FIG. 18 illustrates the operation of the circuit in FIG. 17;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 high voltage power supply 2 charging resistor 3 high voltage switching element 4 main capacitor 5 charging reactor 6 floating inductance 6a reactor 6b saturable realtor 7, 7a to 7c peaking capacitors 8a to 8c reactor 9, 9 ', 9 "... Preionization electrode pair 10 ... Main discharge electrode pair 11 ... Laser oscillator 12 ... Excimer laser tube 14 ... Mirror 15 ... Beam attenuator 16 ... Beam homogenizer 17 ... Laser beam 18 ... Quartz window 19 ... Annealing Chamber 20 Semiconductor substrate 21 Tray 22 Tray driving device

Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H01S 3/0975 H01S 3/097 D 3/0977 EZ

Claims (14)

[Claims] 1. A container for enclosing an excitation gas, a pair of main discharge electrodes provided in the container so as to face each other, a plurality of pairs of preliminary ionization electrodes arranged for these main discharge electrodes,
A charge / discharge circuit including a main capacitor for charging / discharging the power supplied between the preliminary ionization electrodes, a power supply for supplying power to the charge / discharge circuit, and the pair of main discharge electrodes for storing power from the main capacitor A pulse gas laser oscillation device comprising: a peaking capacitor connected in parallel to a reactor; a reactor connected in series to the peaking capacitor; and an optical resonator that amplifies light generated at the main discharge electrode. Comprises a plurality of stages connected in parallel to a main discharge electrode via the reactor having different inductance values. 2. The capacitance values of the main capacitor and the peaking capacitor having a configuration in which a plurality of stages are connected in parallel to the pair of main discharge electrodes, and the inductance values of the reactors respectively connected to the peaking capacitors. 2. The pulse gas laser oscillation device according to claim 1, wherein the setting is performed to control the temporal change of the oscillation light intensity. 3. When there are three peaking capacitors, C1, C2, and C3 are set in order from the side electrically closer to the power supply, and reactors connected in series to these three peaking capacitors are set as L1, L2, and L3. When the main capacitor is set to Cm, the capacitance values of the peaking capacitor and the main capacitor are expressed as "C1
3. The pulse according to claim 2, wherein the relations of "C2 ≒ C3" and "Cm ≒ C1 + C2 + C3" are satisfied, and each inductance value of these three reactors satisfies the relation of "L1 <L2 <L3". Gas laser oscillation device. 4. When there are two peaking capacitors, C1 and C2 are electrically connected to the power supply in a direction closer to the power supply. Reactors connected in series to these two peaking capacitors are set as L1 and L2, respectively. If Cm is set, the capacitance values of these peaking capacitor and main capacitor are “Cm ≒ C1 + C2”.
And the respective capacitance values of these peaking capacitors and the respective inductance values of these reactors are “2 (L1 · C1) ^1/2 <(L2 · C2)
The pulse gas laser oscillation device according to claim 2, wherein a relationship of " ^1/2 " is satisfied. 5. When there are two peaking capacitors, C1 and C2 are electrically connected to the power supply in a direction closer to the power supply. Reactors connected in series to these two peaking capacitors are denoted by L1 and L2. Is defined as Cm, and the reactor connected in parallel with the saturable reactor on the electric path from C1 to C2 is defined as Ls, and the capacitance values of these peaking capacitor and main capacitor are expressed as “Cm ≒ C1 + C2”. The relationship is satisfied, and each capacitance value of these peaking capacitors and each inductance value of these reactors are “2 (L1 · C1) ^1/2 <((L2 + Ls) · C2)
The pulse gas laser oscillation device according to claim 2, wherein a relationship of " ^1/2 " is satisfied. 6. The pulse gas laser oscillation device according to claim 1, wherein the peaking condenser and the reactor are provided outside the container and are detachably provided. 7. A container for enclosing an excitation gas, a pair of main discharge electrodes provided in the container so as to face each other, a plurality of pairs of preliminary ionization electrodes arranged for the main discharge electrodes,
A charge / discharge circuit including a main capacitor for charging / discharging the power supplied between the preliminary ionization electrodes, a power supply for supplying power to the charge / discharge circuit, and the pair of main discharge electrodes for storing power from the main capacitor A pulse gas laser oscillation unit including a peaking capacitor connected in parallel to a reactor, a reactor connected in series to the peaking capacitor, and an optical resonator that amplifies light generated at the main discharge electrode, and a target object. In a laser annealing apparatus having a chamber to be stored and irradiation means for irradiating the object to be processed with pulsed light output from the pulsed gas laser transmission unit, the peaking capacitors are respectively provided via the reactors having different inductance values. Laser annealing characterized in that a plurality of stages are connected in parallel to the main discharge electrode Device. 8. A capacitance value of each of the main capacitor and the peaking capacitor having a configuration in which a plurality of stages are connected in parallel to the pair of main discharge electrodes, and an inductance value of a reactor connected to each of the peaking capacitors. 8. The laser annealing apparatus according to claim 7, wherein the setting is performed to control a change with time of the oscillation light intensity. 9. When there are three peaking capacitors, C1, C2, and C3 are set in order from the side electrically closer to the power supply, and reactors connected in series to these three peaking capacitors are set as L1, L2, and L3. When the main capacitor is set to Cm, the capacitance values of the peaking capacitor and the main capacitor are expressed as "C1
9. The laser according to claim 8, wherein the relationship of ≒ C2 ≒ C3 ”and the relationship of“ Cm ≒ C1 + C2 + C3 ”are satisfied, and the inductance values of these three reactors satisfy the relationship of“ L1 <L2 <L3 ”. Annealing equipment. 10. In the case where there are two peaking capacitors, C1 and C2 are set from the one electrically closer to the power supply,
When the reactors connected in series to these two peaking capacitors are denoted by L1 and L2 and the main capacitor Cm, respectively, the capacitance values of the peaking capacitor and the main capacitor are expressed as "Cm ≒ C1 + C2".
And the respective capacitance values of these peaking capacitors and the respective inductance values of these reactors are “2 (L1 · C1) ^1/2 <(L2 · C2)
The laser annealing apparatus according to claim 8, wherein the relationship of " ^1/2 " is satisfied. 11. When the number of the peaking capacitors is two, C1 and C2 are set from the one electrically closer to the power supply,
Reactors connected in series to these two peaking capacitors are denoted by L1 and L2, the main capacitor is denoted by Cm, and a reactor connected in parallel with the saturable reactor on the electric path from C1 to C2 is denoted by Ls. In other words, the capacitance values of these peaking capacitors and the main capacitor satisfy the relationship of "CmmC1 + C2", and the capacitance values of these peaking capacitors and the inductance values of these reactors are "2 (L1.C1)". ^1/2 <((L2 + Ls) C2)
The laser annealing apparatus according to claim 8, wherein the relationship of " ^1/2 " is satisfied. 12. The laser annealing apparatus according to claim 7, wherein said peaking condenser and said reactor are provided outside said container so as to be detachable. 13. A method for manufacturing a semiconductor device, comprising a step of annealing an amorphous semiconductor substrate using pulsed laser light, wherein a half-value width of a part of the amorphous semiconductor substrate is 50 [n].
[S] annealing the amorphous semiconductor substrate by scanning the pulsed laser light relative to the amorphous semiconductor substrate while repeatedly irradiating light with the pulsed laser light having the pulse width of not less than [S]. Manufacturing method of a semiconductor device. 14. The pulse laser beam is irradiated on a portion of the amorphous semiconductor substrate relative to the amorphous semiconductor substrate while repeating light irradiation with a pulse laser beam having a pulse width of 50 [ns] or more. A semiconductor device using a polycrystalline semiconductor substrate which has been scanned and annealed.