JPH0521340A - Thin film semiconductor device, method and apparatus for manufacturing the same - Google Patents

Abstract

PURPOSE:To form a P-type semiconductor region and an N-type semiconductor region at arbitrary positions by forming a semiconductor layer of single crystalline thin film semiconductor layers exhibiting P-type and n-type conductivities, and incorporating impurities for deciding conductivities in an insulating board surface formed with the semiconductor layer. CONSTITUTION:A B element invaded layer as an impurity for P-type controlling a conductivity type of a recrystallized film and a P element invaded layer as an impurity for N-type controlling a conductivity type of a recrystallized film are formed as impurity layers 72 on a surface of a glass support board 71. A B element invaded layer 72' and a P element invaded layer 72'' are alternately formed in a board state in a stripe shape. A polycrystalline silicon thin film 72 is formed by a band region melting and recrystallizing method, matched to the layer 72 and formed in a stripe shape. After a surface protective film 74 is formed, a polycrystalline silicon thin film sample is simultaneously irradiated, heated, melted with Ar laser light and a carbon dioxide gas laser light 2, and single crystallized by a band region melting and recrystallizing method.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a single crystal thin film semiconductor device, a manufacturing method thereof, and a manufacturing apparatus thereof.

[0002]

2. Description of the Related Art Many methods for forming a single crystal semiconductor thin film on an insulating substrate, that is, a so-called SOI forming method have been proposed in the past. In most of these, an amorphous or polycrystalline semiconductor thin film is formed on an insulating substrate, and the amorphous or polycrystalline semiconductor thin film is zone-melted and recrystallized by various heat sources to be single crystallized. In this case, the heat source includes laser light, electron beam, various lamp lights,
There is a carbon heater having a wire shape. In these conventional techniques, the semiconductor material is recrystallized in a non-doped state in which the semiconductor material does not contain impurities at the time of melting and recrystallization, and then impurities are introduced at the time of forming a device on the SOI. This is because it is difficult to form the P-type semiconductor region and the N-type semiconductor region in an arbitrary region on the substrate because the conditions for recrystallization change if impurities are introduced during recrystallization. Therefore, when a device is formed using a substrate of a recrystallized film, a step of introducing impurities is required, which is a cause of reducing the yield because the step is complicated.

[0003]

It is an object of the present invention to improve the above-mentioned defects of the SOI substrate and to provide an SOI substrate in which a P-type semiconductor region and an N-type semiconductor region are formed at arbitrary positions. Further, the present invention provides a method and an apparatus for manufacturing an SOI substrate as described above by using laser light as a heat source for the zone melting recrystallization method in the SOI forming method.

[0004]

According to a first aspect of the present invention, in a thin film semiconductor device having a semiconductor layer on an insulating substrate, the semiconductor layer is formed in an island shape or a band shape on the insulating substrate, and has a p-type conductivity and an n-type conductivity. A thin film semiconductor, wherein the single crystal thin film semiconductor layer shown in the figure contains the same impurities as those determining the conductivity at least on the surface of the insulating substrate in the region where the single crystal thin film semiconductor layer is formed. Regarding the device. The second aspect of the present invention is to form an impurity penetration layer on an insulating substrate,
An amorphous or polycrystalline thin film semiconductor layer is formed thereon in an island shape or a band shape, and then a surface protective layer is formed on the thin film semiconductor layer, and the first laser light absorbed by the thin film semiconductor layer is insulated from the first laser light. Using the second laser light absorbed by the flexible substrate,
The thin-film semiconductor device is heated by the first laser beam in a state where the thin-film semiconductor layer is preheated by the heat generation of the insulating substrate by the second laser beam, thereby performing zone melting recrystallization. Regarding manufacturing method. Third of the present invention
Is a first laser beam emitting means for emitting a first laser beam absorbed by the amorphous or polycrystalline thin film semiconductor layer, and a second laser beam for emitting a second laser beam absorbed by the insulating substrate. The present invention relates to a device for manufacturing the thin film semiconductor device, which has a light emitting means.

Silicon will be described in detail below as the semiconductor thin film layer of the present invention. However, the present invention is not limited to silicon, but may be a group IV, III-V, II-VI group simple substance or a compound semiconductor. Therefore, it can be applied to all materials whose crystal structure has a diamond structure or a zinc blend structure. Specifically, in addition to Si, Ge, SiC,
BN, BP, BAs, AlP, AlSb, GaP, Ga
As, GaSb, InP, InAs, InSb, Zn
S, ZnSe, ZnTe, CdS, CdSe, CdT
e, CdHg, etc.

According to the method of manufacturing a thin film semiconductor device disclosed in the present invention, when a single crystal silicon thin film is formed on an insulating substrate by a zone melting recrystallization method, the laser light absorbed by silicon and the laser beam absorbed by the insulating substrate are absorbed. The laser light is irradiated as described above to melt and recrystallize silicon, but when the two laser lights are irradiated to melt and recrystallize the silicon layer, the output of the two laser lights, the beam shape, and the irradiation By changing the irradiation conditions such as position and controlling the temperature profile of the molten recrystallized region of the silicon layer, the single crystal silicon thin film is processed to have an island-shaped or strip-shaped P-type semiconductor region or N-type semiconductor region. is there.

The formation of single crystal silicon by the melt recrystallization method of amorphous or polycrystalline silicon formed on an insulating substrate can be explained as follows. Amorphous or polycrystalline silicon formed on an insulating substrate by various heat sources is heated and melted (melting point of silicon 1412
C.), when the heated portion is relatively scanned on the silicon layer, the molten silicon is cooled and solidified and recrystallized as the heat source moves. At this time, when the temperature distribution of the part melted by heating is high in the central part and low in the peripheral part as shown in FIG. 1, recrystallization of the molten silicon starts simultaneously from the periphery of the molten part. As a result, the recrystallized silicon becomes polycrystalline. In order to prevent such polycrystallization and perform recrystallization, the temperature profile in the melting region (the temperature profile described in the present invention means the melting recrystallization process of silicon, that is, heating, melting, cooling, The change in temperature in a series of phenomena of solidification is represented by measuring the temperature in one or more of the above-mentioned states, or by measuring the physical quantity representing the temperature.) It is known to do well. By doing so, recrystallization always starts from the central portion as shown in FIG. 2, and recrystallized silicon is obtained as a single crystal. Laser light is mainly used as the heating source, and the scanning speed of the heat source is about several tens cm / sec. Another method of forming a single-crystal silicon thin film on an insulating substrate by the melt recrystallization method is the zone melt recrystallization method (Zone
Melting Recrystallization). The state of formation of single crystal silicon by this method is described as follows. The outline is shown in FIG. 3. When the silicon layer to be melted and recrystallized is heated and melted in a band shape, the silicon layers other than the region 8 melted in the band shape are heated to a temperature near the melting point of silicon. Then, the molten region is moved to solidify and recrystallize silicon to obtain single crystal silicon. At this time, as shown in FIG. 4, there is a supercooled region in which the liquid state is maintained even after the melting point of silicon exceeds 1412 ° C. at the solid-liquid interface of the solidification of the molten silicon, and the solidification of the recrystallization of silicon occurs. It is said that the liquid interface is formed by a collection of facets (small crystal faces) of the (111) face, which is the slowest growing crystal face of silicon in the supercooled region. The formation of single crystal silicon is performed by moving the supercooled region along with the movement of the band-shaped melting region 8 and continuously growing the facet plane composed of the (111) face of silicon in the supercooled region. It is something. As a method of forming the band-shaped molten region, there is a method of heating with a linear carbon heater placed in proximity to the substrate, an RF induction heating method, or the like. The moving speed of the band-shaped melting region in this method is approximately several mm / sec, and it can be said that the characteristic of this method is that a state close to thermal equilibrium is realized at the solid-liquid interface of recrystallization. A recrystallized single crystal silicon thin film formed by such a zone melting recrystallization method is used as the insulating substrate made of quartz glass (or SiO ₂
Layer), and in the case of SiO ₂ formed by thermal CVD as a surface protection film at the time of recrystallization, the crystal orientation plane of the recrystallized film should be the (100) plane even though a seed crystal is not used. It has been known.

The present inventors have paid attention to this zone melting recrystallization method and have invented a zone melting recrystallization method using a heating means having a function different from the conventional heating method. As a result, using the method of the present invention, a thin film semiconductor device having a thin film single crystal semiconductor layer having a P-type semiconductor region and an N-type semiconductor region on the same substrate, which was difficult in the conventional zone melting recrystallization method, is obtained. I was able to. The technical background of the present invention will be described. In the present invention, two types of laser light are used as a heating source: laser light absorbed by silicon (hereinafter referred to as first laser light) and laser light absorbed by the insulating substrate (hereinafter referred to as second laser light). . This is because these laser beams are extremely suitable heat sources for forming single crystal silicon on the insulating substrate by the zone melting recrystallization method. First, the advantages of the laser heating method in comparison with other heating methods in the zone melting recrystallization method will be described. FIG. 10 shows a heating state by a linear heater generally used as a heating source in the zone melting recrystallization by the conventional method. In the temperature range near the melting point of silicon, the heating from the linear heater of the heat source is mainly radiant heating. In such a case, the amount of heat received from the heat source at any point on the substrate is calculated by the following formula (1). To be done.

[Equation 1] As is clear from the description of equation (1), the distance between the heat source and the substrate influences the squared weight. That is, in order to realize a temperature profile for stably performing zone melting recrystallization by radiant heating, it is necessary to precisely control the distance between the heat source and the substrate. The requirement for this heat source is not limited to the case of the linear heater, and even in the case of other heat sources, the heating method is inevitable as long as the heating method is radiant heating. On the other hand, when the heating source is laser light, heat is generated by absorption of the laser light, so the temperature profile on the substrate is not affected by the distance between the substrate and the laser light source, and the laser light If excellent parallelism is taken into consideration, it is possible to guide the light source from any position onto the substrate. Further, in the zone melting recrystallization method using the conventional heating method, it is necessary to form a supercooled region at the solid-liquid interface of recrystallization, and therefore the cooling rate must be reduced. Therefore, it was necessary to heat the entire substrate to near the melting point of silicon in order to reduce the thermal gradient at the solid-liquid interface. Therefore, the substrate after the zone melt recrystallization was often heated and deformed by heating at a high temperature for a long time. In addition, the size of the substrate may be restricted due to the size of the heating device becoming large or restrictions on the device. On the other hand, when laser light is used as the heat source, the laser light has a sufficiently high energy density compared to other heating methods, so the laser irradiation area resists the escape of heat to the surroundings, It is possible to maintain a sufficiently high temperature. Therefore, it is not necessary to heat the entire substrate to a high temperature near the melting point of silicon, there is no problem of deformation of the substrate due to high temperature heating that has been observed in the conventional zone melting recrystallization method, and there is a limitation on the apparatus for heating the substrate. Nor. In addition to the above characteristics of using laser light as a heating source, the size of laser light can be changed arbitrarily by combining various optical parts such as lenses and mirrors, and it is possible to guide the laser light to any place. Therefore, it is possible to selectively perform the zone melting recrystallization process on only a part of the substrate, which has been difficult to realize by the conventional heating method. Further, the absorption of laser light into the material generally remains at a depth of several tens of μm from the surface of the material, so that when the laser is used as the heating source, only the very surface of the substrate is heated. By forming an appropriate heat-resistant layer on the substrate surface by this, it is possible to use a substrate having a melting point or a softening point lower than that of silicon, which could not be realized by the conventional zone melting recrystallization method, as a support substrate. Is.

The present invention has a new feature in addition to the advantage of using a laser beam as a heating source in the above-mentioned zone melting recrystallization, since it uses the above two types of laser beams. FIG. 8 shows a state of zone melting recrystallization by the method disclosed in the present invention. When the silicon layer (semiconductor layer) 2 formed on the insulating substrate 1 is simultaneously irradiated with the above-mentioned first laser beam 4 and second laser beam 5, the first laser beam 4 is absorbed by the silicon layer 2. Generates heat. The second laser light 5 is absorbed in the substrate 1 to generate heat. That is, the silicon layer 2 is heated by the first laser light 4 in a state of being preheated by the second laser light 5. As shown in FIG. 9, the temperature profile of the heating region with the two types of laser light at this time is such that the beam diameter (α ₂ ) of the second laser light is large and the first laser beam diameter (α ₁ ) is narrow. A molten region of silicon can be formed by optimizing the outputs of two types of laser light. Such a temperature profile is essentially the same as the temperature profile for realizing the zone melting recrystallization as shown in FIG. 3 in the region heated by the laser light, and such a temperature profile is maintained. By reciprocally scanning the beam with respect to the substrate, recrystallized single crystal silicon can be obtained by the mechanism of the zone melting recrystallization described above. Furthermore, in this method, heat generation by irradiation of the first laser light occurs in the silicon thin film layer, and heat generation by irradiation of the second laser light occurs in the insulating substrate. It has a great feature that it can be generated. The present inventors have paid attention to the characteristics of this two-wavelength laser zone melting recrystallization method, and have studied in detail the zone melting recrystallization method of a silicon thin film on an insulating substrate by this method. A single crystal silicon thin film having P-type and N-type semiconductor regions was obtained.

The components of the thin film semiconductor device according to the present invention will be described below with reference to FIG. The support substrate 1 is made of an insulating material. An insulating material having heat resistance such as quartz glass or ceramics is used as the simple substance, but a substrate having a suitable insulating film formed on a metal or a semiconductor can also be used as the support substrate of the present invention. . Specifically, SiO ₂ , Si ₃ N _4, etc. are formed as an insulating material on a silicon wafer. Alternatively, on a metal such as Fe, Al, or Cu, SiO ₂ , Si ₃ N ₄
Those formed with an insulating material such as can also be used as the support substrate. Further, by forming the heat resistant layer, a material having a lower melting point than silicon can be used as the support substrate. Insulating materials for the heat-resistant layer include SiO ₂ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , and Si _3.
N ₄ , BN and the like, and conductive ones such as TiC and SiC. When the heat resistant layer is made of a conductive material, it must be used in combination with the above insulating material. In some cases, a plurality of heat resistant materials can be used in combination. Plasma CVD, thermal CV for these materials
D method, photo CVD method, LP-CVD method, MO-CVD method, sputtering method, vacuum deposition method, various deposition methods such as ion beam cluster deposition method, and various material modification such as ion implantation method It is formed using a method. When an insulating material is formed on a semiconductor or metal material to be used as a support substrate, or when a heat-resistant layer or an insulating layer is formed on a low-melting-point material to be used as a support substrate, the thickness of the insulating layer or heat-resistant layer It is desirable to determine the thickness in consideration of the absorption of the second laser light of the material used. For example, carbon dioxide gas laser light is used as the second laser light, and Si is used as the insulating layer or heat-resistant layer material.
When O ₂ is formed, its thickness is about 50 μm. When an insulating material such as a quartz glass substrate is used alone as a support substrate, a dimension sufficiently thicker than the absorption thickness of the laser is usually selected because of the requirement of maintaining its mechanical strength.
Its value is usually 0.3mm ~ 5.0mm, preferably 0.5mm ~
It is 2.0 mm. The impurity penetration layer 1'is a layer formed to control the conductivity type of the recrystallized film. When the recrystallized film is silicon and p-type conduction is desired, a group III element of the periodic table is selected as an impurity. Specifically, B, Al, G
a, In and the like. Further, when the N-type conduction is desired, a group V atom of the periodic table is selected as an impurity. In particular,
P, As, Sb, etc. Various methods are possible as a method for forming a layer containing these elements on a support substrate. For example, the impurity intrusion layer can be formed by a method of ionizing the above-mentioned elements and accelerating them in a vacuum at high speed by the effect of an electric field so as to collide with the substrate, that is, an ion implantation method. Since this method can control the ion beam with high precision, it is possible to form an impurity invasion layer made of different elements at arbitrary positions on the substrate. The impurity intrusion layer formed by this method is not clearly distinguished from the support substrate, and can be considered to be substantially a modified layer of the support substrate. It is also possible to form the film containing the impurities by a film forming method. For example, a layer containing P as an impurity can be formed by a thermal CVD method using PH ₃ , SiH ₄ , and O ₂ as source gases. This layer controls the conductivity type of the recrystallized film formed thereon to be N type. The thickness of this impurity penetration layer takes a relatively large range depending on the formation method, and when the impurity penetration layer is formed directly in the support substrate by the ion implantation method or the like, the thickness is several tens to several hundreds. Although the thickness is about Å, when it is formed by the film forming method, the thickness reaches several μm. Impurity atoms existing in the impurity intrusion layer 1'are heated by the laser light absorbed by the substrate in the next step of irradiating the laser beam and diffused into the silicon layer, so that the conductivity type of the silicon layer is changed. Decide The silicon layer 2 single-crystallized on the support substrate 1 by the two-wavelength laser zone melting recrystallization method is composed of polycrystalline silicon or amorphous silicon. This silicon layer 2 is formed by plasma CVD method, thermal CVD method, photo CVD method, LP
-CVD method, MO-CVD method, sputtering method, vacuum deposition method,
It is formed by using various film forming methods such as an ion beam cluster film forming method, and various material modifying methods such as an ion implantation method. Further, the silicon layer 2 may be processed into an arbitrary shape by using a usual photolithography method when it is judged necessary in the zone melting recrystallization process. Specifically, it has a stripe shape, an island shape, or a connection island shape as shown in FIGS. 5, 6, and 7, but any of these purposes limits movement of the silicon melt on the support substrate 1. Therefore, it is intended to improve the stability of facet growth, and is a technique often used conventionally by the zone melting recrystallization method. Such a silicon layer 2
Although the above process contributes to the improvement of the film thickness uniformity of the single crystal silicon layer obtained by recrystallization, it does not determine the orientation. The film thickness of the silicon layer 2 can be used for recrystallization in the range of 0.1 μm to 5.0 μm, and is preferably in the range of 0.3 μm to 1.0 μm. The surface protection film 3 is indispensable for forming a single crystal silicon thin film by the zone melting recrystallization method. This is formed for the purpose of preventing a rounding phenomenon (bead-up phenomenon) due to evaporation of molten silicon or surface tension in the zone melting recrystallization process. The surface protection layer 3 is made of an insulating material, and a desirable material is Si.
O ₂ , SiO, Si ₃ N ₄ , and SiN, which are formed alone or in combination in the silicon layer 2.
As the method for forming the surface protective film 3, there are plasma CVD method, thermal CVD method, photo CVD method, LP-CVD method, MO-CVD method.
Methods, sputtering methods, vacuum evaporation methods, various film forming methods such as ion beam cluster film forming methods, and methods for modifying various materials such as ion implantation methods. The film thickness is generally optimized in the range of 0.5 μm to 5.0 μm, and is preferably 1.0 μm to 2.
It is 0 μm. The surface protective layer 3 may be removed in the step of forming a semiconductor element using the thin film semiconductor device according to the present invention as a raw material.

As the first laser beam in the two-wavelength laser band melting recrystallization method of the present invention, a laser beam which emits light having a wavelength in the absorption band (wavelength side shorter than about 1.2 μm) to silicon can be widely used. Specifically, various excimer lasers in the short wavelength region, He-Cd lasers, Ar lasers,
A He-Ne laser, a ruby laser, an alexandrite laser, a YAG laser, a semiconductor laser, or the like can be used. From the viewpoint of using as a heat source that forms the temperature profile necessary for zone melting recrystallization, it is desirable that the output that can be taken out is relatively large, and that a laser capable of continuous oscillation is used. Ar laser, YAG laser,
Alternatively, it is desirable to select from high-power semiconductor lasers. These laser lights can be expanded by inserting a laser beam expander in the middle of the beam in order to widen the irradiation area. Furthermore, it is also possible to combine multiple laser beams to use them. Is also possible. As a beam shape for irradiating the silicon layer, a uniform linear beam is preferable as it is suitable for realizing the zone melting recrystallization method. It is possible to make the beam shape linear and uniform using various optical machines. Further, as described above, it is possible to form a uniform and linear beam from a plurality of beams. Further, it is also possible to form a pseudo linear beam by high-speed scanning of the beam. As the second laser light used for preheating the substrate, laser light having absorption in the insulating material can be widely used. Laser light in the infrared region is widely absorbed by the insulating material, and is suitable as the second laser light. Specifically, a carbon dioxide gas laser or a carbon monoxide gas laser can be used.
The beam shape of the second laser beam does not necessarily have to be linear. In the case of irradiating with the first laser beam described above, it is sufficient if the beam shape is large enough to control the thermal profile of recrystallization of silicon by melting due to heating of the first laser. Assuming that the length of the first laser beam linearly formed as 14 is L ₁ , the length L ₂ of the second laser in this direction needs to be L ₂ > L ₁ , and preferably L ₂ >. It is 1.2L ₁ . The laser beam is usually obtained in a round shape, but it can be used in various shapes such as an elongated elliptical shape or a substantially rectangular shape.

The second laser is used as a heat source for the zone melting recrystallization of the silicon layer together with the first laser light.
The heating with the first laser light is mainly used for melting the silicon, while the heating with the second laser light is used for controlling the cooling solidification recrystallization process of the molten silicon. Therefore, the region heated by the second laser light must have a uniform temperature profile. Therefore, the beam of the second laser light needs to have a uniform power density in a wider area than the beam of the first laser light. It is possible to flatten the beam output using various optical devices such as a kaleidoscope and a segment mirror. Further, as in the case of the above-mentioned first laser light, a plurality of laser beams may be combined to form a flat combined beam. It is also possible to flatten the temperature profile of the heating part by scanning the beam. Further, as the laser light, it is also possible to use pulsed laser light in addition to continuous wave laser light. In this way, the beam of the second laser light is approximately the first beam.
Is irradiated onto the substrate in such a manner as to surround the beam of the laser light of the second laser beam. Even if the beam intensity is uniform in the vicinity of the outer periphery of the beam of the second laser light due to a large temperature difference inside and outside the beam. A temperature gradient may occur. In such a case, the temperature can be flattened by using a beam profile in which the outer peripheral portion of the beam is emphasized.

The first laser beam and the second laser beam used in the two-wavelength laser band melting recrystallization method are not only the above-mentioned configuration but also change in temperature of the place where each laser beam is irradiated. Must be able to modulate accordingly. The present invention is based on stably obtaining a recrystallized film of single crystal silicon by the zone melting recrystallization method. In order to realize such stable melt recrystallization, it is necessary to control the output of the laser light to be irradiated by feedback. This is because the amount of heat generated by the absorption of the first laser light or the second laser light changes due to various factors such as the film thickness of the absorbing layer and the reflectance of the surface. Therefore, the feedback control of the light intensity is necessary to stably control the temperature profile through the zone melting and recrystallization process. Furthermore, for the reasons described above, it is necessary to control the temperature profile in order to control the orientation. As such a feedback control of the light intensity of the laser, there is a method in which the temperature information of the irradiation unit is taken in as a feedback signal into the laser power supply circuit to control the laser output as shown in FIG. Or figure
As shown in 16, it is also possible to place a mechanism for continuously changing the light intensity between the laser oscillator 12 and the sample by an external signal and control this mechanism according to the temperature change of the irradiation unit. As a mechanism for continuously changing the light intensity, for example, a combination of two deflecting plates may be used. The method of irradiating the first and second laser beams having such a feedback control mechanism of the optical output is such that the thermal profile as shown in FIG. There is no particular limitation as long as the irradiation method can realize the crystallization method. Further, regarding the thermal profile shown in FIG. 9, it is not necessary for the thermal profile to be symmetrical with respect to the scanning direction of the beam, since the process from the molten state to the solidification is important for the zone melting recrystallization. Specific examples of the present invention will be described below.

[0014]

EXAMPLES Example 1 In this example, an Ar laser beam and a second laser beam were used as the first laser beam.
Carbon dioxide laser light was used as the laser light. As shown in FIG. 17, the Ar laser beam 51 emitted from the Ar laser oscillator 27 has a beam diameter of 1.9 mm in a multi-line oscillation state, and a convex lens 26 is used to form a linear beam shape.
Is arranged so as to form a focus on the sample 21, and a mirror 28 provided with a vibrating mechanism 27 is arranged between the convex lens 26 and the sample 21, and the beam spot on the sample 21 is in a direction orthogonal to the scanning direction of the laser light. Vibrate to form a linear thermal profile on sample 21. The carbon dioxide gas laser light was guided onto the sample 21 via four mirrors 31, 32, 33 and 34 using four carbon dioxide gas laser oscillators 35, 36, 37 and 38, respectively. The beam diameter of the carbon dioxide laser light is 5 mm, and the convex lens (47,48,49,50)
The beam was focused on the substrate through the so that the beam diameter would be 200 μm. The Ar laser beam 51 is used for the temperature detection unit 29 including a radiation thermometer.
And control the laser power supply 23 from the feedback control unit 24,
The output is controlled so that the temperature of the measuring unit becomes constant through the scanning of the beam. Also carbon dioxide laser light 52,5
Similarly to the Ar laser light 51, the laser power sources 39, 40, 41 and 42 are controlled by the temperature detection unit 30 and the feedback control unit 43 which are radiation thermometers. The substrate on which the recrystallized film is formed is prepared as follows. In FIG. 11, as the support substrate 71, a transparent quartz glass substrate having a thickness of 1.0 mm was used. After the glass support substrate 71 is washed by a conventional method, an ion implantation method is applied to the surface of the glass support substrate 71 to inject the B element as an impurity for controlling the conduction type of the recrystallized film into the P type and the conduction of the recrystallized film. An intrusion layer of P element as an impurity for controlling the type to N type was formed on the same substrate as an impurity layer 72. Ion implantation is performed by deflecting the beam into two axes, the X-axis and the Y-axis. As shown in FIG. 12, a B element intrusion layer 72 ′ and a P element intrusion layer 72 ″ are alternately formed on the substrate in a width of 100 μm. was formed to the spacing of the stripes 100μm in stripe. injection conditions of the respective impurity acceleration voltage 80keV for element B, implantation of 5 × 10 ¹⁴ / cm ² and is for P element accelerating voltage 50 keV, Driving amount 5 × 10 ¹⁵ /
It is cm ² . Low pressure chemical vapor deposition equipment (LPCVD equipment)
Was used to form a polycrystalline silicon thin film 73 as a silicon layer to be single-crystallized by the zone melting recrystallization method. Its film thickness is 3500Å. Next, the polycrystalline silicon thin film 73 was processed by photolithography to be aligned with the impurity layer 72 and processed into stripes having a width of 100 μm, such as 72 ′ and 72 ″, with a stripe interval of 100 μm. SiO ₂ as a surface protection layer at the time of zone melting recrystallization using LPCVD equipment on 72 ′, 72 ″
The thin film 74 was formed to a thickness of 1.2 μm. The polycrystalline silicon thin film sample thus formed is irradiated with the aforementioned Ar laser light (first laser light) and carbon dioxide gas laser light (second laser light) at the same time, heated, melted, and monocrystallized by the zone melting recrystallization method. To do. The arrangement of the first laser light and the second laser light is as follows. A so that it is orthogonal to the polycrystalline silicon stripe
The r laser light 51 was vibrated using the mirror 28. The vibration frequency of the mirror at this time was set to 1 kHz. The amplitude of the mirror was set so that the deflection width of the beam of the Ar laser light 51 was 110 μm on the silicon layer. The four carbon dioxide gas laser beams 52,53,54,55 emitted from the four carbon dioxide laser oscillators 35,36,37,38 face each other so as to surround the irradiation position of the linear Ar laser beam 51 as shown in FIG. Beam spacing 200μm
(Fig. 18 is a specific example satisfying the relationship of Fig. 14). The output of Ar laser light 51 is kept constant at 2.0 W and four carbon dioxide gas laser lights 52, 53, 54, 55 are generated while oscillating the beam.
The silicon layer at the position irradiated by the oscillating beam of the Ar laser light 51 is melted as the output of the laser is increased. In this state, the thermal profile for zone melting recrystallization as shown in FIG. 9 is realized on the substrate 71. Then, the sample 21 is moved into a linear Ar sample by the sample moving mechanism provided on the stage 25.
When the laser beam is moved so as to be orthogonal to the polycrystalline silicon stripes 72 ′ and 72 ″, the melting zone 8 of silicon at the irradiation portion of the Ar laser light 51 is scanned along with the relative scanning of the laser beam on the sample 21. To the downstream side of the direction,
Cooling and solidification recrystallization is performed while releasing heat to the surroundings that are thermally guarded by the four carbon dioxide laser beams 52, 53, 54 and 55 to form a single crystal stripe with a width of 100 μm. The extension of the silicon melt portion to the downstream side at this time varies depending on the moving speed of the sample, the output of the carbon dioxide laser light, etc., but the moving speed of the sample 21 is 1 mm / s, and the four carbon dioxide laser lights 52,53,54,55. When the output of each was 15 W, the extension of the molten silicon to the downstream side was about 0.5 mm. Then, the temperature detecting unit 29 detects the temperature of the silicon melt in the irradiation portion of the Ar laser light 51 (temperature measuring unit A), and the temperature is kept constant by the control method described above.
The output of the r laser light 51 is controlled, and the temperature at a position of 500 μm further downstream from the solidification portion of the silicon melt which extends downstream with the scanning of the sample 21 is detected by another temperature detection unit 30. (Temperature measuring section B) Similarly, the outputs of the four carbon dioxide gas laser beams 52, 53, 54 and 55 were controlled by the above-mentioned control method so that the temperature was kept constant. In this way, by controlling the temperatures at the two temperature measuring portions A and B to be constant, it was possible to obtain a stable recrystallized film over the entire scanning of the laser light on the substrate. In this example, the temperature condition for recrystallization of the element B on the intrusion layer,
When the temperature conditions for recrystallization of the P element and the P element on the penetration layer are set to 1423 to 1427 ° C in the temperature measuring section A and 1345 to 1350 ° C in the temperature measuring section B, the laser beam scanning is performed on the same substrate. The orientation plane of the single crystal silicon is (100) plane orientation. At this time, the laser output conditions at the time of recrystallization on the penetration layer of B element and recrystallization on the penetration layer of P element are shown in the table below. It was the range shown in 1. By repeating the above operation, the polycrystalline silicon stripe on the substrate was single-crystallized by the two-wavelength laser zone melting recrystallization method. After that, the SiO ₂ thin film of the surface protective layer was removed by etching with a buffered hydrofluoric acid solution. As a result of hole measurement, the obtained recrystallized silicon thin film shows that the recrystallized silicon on the B element intrusion layer exhibits P-type conduction and the recrystallized silicon on the P element intrusion layer exhibits N-type conduction. I understood. As described above, the thin film semiconductor device disclosed in claim 1 of the present invention is completed.

[Table 1]

[0015]

Since the thin film semiconductor device disclosed in claim 1 of the present invention has different conductivity types of P type and N type on the same insulating substrate, when a semiconductor device is formed using this member. Moreover, the process for introducing impurities can be simplified, and the yield can be improved. According to the manufacturing method disclosed in claim 2, the thin film semiconductor device according to claim 1 can be efficiently obtained. Claim 3 provides a manufacturing apparatus therefor.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing polycrystallization depending on the temperature distribution in the melt recrystallization method.

FIG. 2 is a schematic view showing single crystallization depending on the temperature distribution in the melt recrystallization method.

FIG. 3 (a) shows a preferable temperature distribution of a silicon thin film in the direction of recrystallization (arrow), and the melting point of silicon is 1412.
The point where the temperature exceeds ℃ is the point where melt recrystallization is performed. (b) is a schematic view of a thin film semiconductor device made of an insulating substrate having a layer of a silicon thin film, and 8 shows a molten portion of silicon.

FIG. 4 is a state diagram of a solid-liquid interface of molten silicon.

FIG. 5 is a plan view of a thin film semiconductor device showing a case where a silicon layer provided on an insulating substrate has a stripe shape.

FIG. 6 is a plan view showing an example of a planar arrangement of silicon layers of the present invention.

FIG. 7 is a plan view showing an example of a planar arrangement of silicon layers of the present invention.

FIG. 8 is a cross-sectional view of a thin film semiconductor showing a state of zone melting recrystallization according to the present invention.

FIG. 9 shows temperature profiles of a heating region by two types of laser beams of the present invention.

FIG. 10 shows a schematic view of a zone melting method using a linear heater.

FIG. 11 is a sectional view of a thin film semiconductor device according to an embodiment of the present invention.

FIG. 12 shows an arrangement state of P-type and N-type conductive layers in an example of the present invention.

FIG. 13 is a cross-sectional view showing an example of a thin film semiconductor device of the present invention.

FIG. 14 is a diagram showing a preferable relative positional relationship between a first laser beam and a second laser beam capable of performing a two-wavelength laser band melting recrystallization method used in the thin film semiconductor device of the present invention.

FIG. 15 shows an example of a laser light intensity feedback system.

FIG. 16 shows another example of a laser light intensity feedback system.

FIG. 17 shows a laser irradiation system according to an embodiment of the present invention.

FIG. 18 shows an example of combined irradiation of a first laser and a second laser.

FIG. 19 is a diagram schematically showing how zone melting and recrystallization is performed with the arrangement of laser light according to the example of the present invention.

[Explanation of symbols]

1 Insulating substrate 1'impurity penetration layer 2 Semiconductor layer (silicon layer) 3 Surface protection layer 4 First laser light 5 Second laser light 8 melting zone 11 Insulating substrate 12 Laser oscillator 13 Laser power supply 14 Feedback control unit 15 Temperature detector 16 Light modulator 21 samples 22 Ar laser oscillator 23 Ar laser power supply 24 Ar laser feedback controller 25 stages 26 Convex lens 27 Mirror vibration mechanism 28 Ar laser mirror 29 Ar laser temperature detector 30 Carbon dioxide laser temperature detector 31 Carbon dioxide laser mirror detector 32 Carbon dioxide laser mirror detector 33 Mirror detector for carbon dioxide laser 34 Carbon dioxide laser mirror detector 35 Carbon dioxide laser oscillator 36 Carbon dioxide laser oscillator 37 Carbon dioxide laser oscillator 38 Carbon dioxide laser oscillator 39 Carbon dioxide laser power supply 40 Carbon dioxide laser power supply 41 Carbon dioxide laser power supply 42 Carbon dioxide laser power supply 43 Feed back controller for carbon dioxide laser 44 Temperature measuring unit A 45 Thermometer B 46 Melting area 47 convex lens 48 convex lens 49 convex lens 50 convex lens 51 Ar laser beam 52 Carbon dioxide laser beam 53 Carbon dioxide laser beam 54 Carbon dioxide laser beam 55 Carbon dioxide laser beam 71 Transparent quartz glass substrate 72 Impurity layer 72 'P-type conductive layer (B element penetration layer) 72 ″ N-type conductive layer (P element penetration layer) 73 Polycrystalline silicon thin film 74 Surface protection layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // H01L 21/268 B 8617-4M

Claims (3)

[Claims] 1. A thin film semiconductor device having a semiconductor layer on an insulating substrate, wherein the semiconductor layer is formed in an island shape or a band shape on the insulating substrate, and is a single crystal thin film semiconductor exhibiting P-type and n-type conductivity. A thin film semiconductor device, comprising a layer, and the same impurities as those determining conductivity are contained in at least the surface of the insulating substrate in the region where the single crystal thin film semiconductor layer is formed. 2. An impurity penetration layer is formed on an insulating substrate,
An amorphous or polycrystalline thin film semiconductor layer is formed thereon in an island shape or a band shape, and then a surface protective layer is formed on the thin film semiconductor layer, and the first laser light absorbed by the thin film semiconductor layer is insulated from the first laser light. Using the second laser light absorbed by the flexible substrate,
2. The zone melting recrystallization is performed by heating the thin film semiconductor layer with the first laser light in a state where the thin film semiconductor layer is preheated by the heat generation of the insulating substrate by the second laser light. Manufacturing method of thin film semiconductor device. 3. A first laser beam emitting means for emitting a first laser beam absorbed by an amorphous or polycrystalline thin film semiconductor layer, and a second laser beam emitted by an insulating substrate. 2. The apparatus for manufacturing a thin film semiconductor device according to claim 1, further comprising a second laser beam emitting means.