JP2002025906A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor which enables uniform and large crystal grains to be formed in an active region of a number of transistors on a glass substrate, and a semiconductor device. SOLUTION: The method has a process for forming a structure wherein a non-single crystal silicon film, a pattern 16a of a light transmitting insulation film, and a pattern 18a of a metallic film whose area is smaller than that of the pattern of the insulation film are laminated from below one by one, and a process for heating a non-single crystal silicon film by casting laser light by using a pattern of a metallic film as a mask through a pattern of an insulation film, and dissolving a part of the non-single crystal silicon film. After a molten region of a non-single crystal silicon film is enlarged through heat conduction and the non-single crystal silicon film below a pattern of a metallic film is dissolved, the molten non-single crystal silicon film is cooled and crystallized, and a polycrystalline silicon 14b is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method for manufacturing a semiconductor device. More specifically, the present invention relates to a thin film transistor used for a liquid crystal panel and the like.

[0002]

2. Description of the Related Art Low power consumption, low voltage operation, lightweight, thin,
Liquid crystal panels characterized by color display and the like are rapidly expanding their applications to personal computers (PCs) and video equipment. In recent years, active matrix driven color liquid crystal panels have been used in cathode ray tubes (cathod ray tube).
(CRT), a high image quality can be expected.

A liquid crystal panel is provided with a thin film transistor (hereinafter, referred to as a TFT). The TFT serves as a switching element, the orientation of the liquid crystal is controlled, and an image is displayed. In a TFT, an amorphous silicon film is usually grown on a glass substrate, and this is used as a channel conductor to constitute a transistor. TFTs are required to have a high response speed in order to improve the image quality of liquid crystal panels. However, since the mobility of the current carrier is lower in amorphous silicon than in single crystal silicon or polycrystalline silicon, there is a limit in increasing the response speed of the TFT.

[0004] Further, since amorphous silicon has a low mobility of a current carrier, a driver IC for driving a TFT cannot be manufactured on a glass substrate simultaneously with the TFT. Therefore,
The driver IC is an ordinary LS using a single crystal silicon substrate.
It is manufactured by the process I and mounted on a liquid crystal panel. Since polycrystalline silicon has a higher current carrier mobility than amorphous silicon, a TFT or driver IC having a desired response speed can be manufactured by using polycrystalline silicon for the active layer. However, polycrystalline silicon is formed by a CVD (Chemical Vapor Deposition) method of thermally decomposing SiH ₄ or the like in a heating atmosphere of 600 ° C. or more. Since the melting point of a glass substrate, which is a substrate used for a liquid crystal panel, is lower than the growth temperature of polycrystalline silicon, polycrystalline silicon having good crystallinity cannot be grown directly on the glass substrate. Therefore, it is necessary to use quartz glass having a high melting point as a substrate on which polycrystalline silicon having good crystallinity and high mobility can be obtained. But,
Since this quartz glass is expensive, it is used only for liquid crystal panels for special purposes, and is not used for general liquid crystal panels.

[0005] As a method of obtaining a polycrystalline silicon film on a glass substrate, first, an amorphous silicon film is formed on a glass substrate by a low-temperature CVD method and irradiated with a short-pulse excimer laser. In many cases, only the amorphous silicon film is melted and crystallized to obtain polycrystalline silicon without affecting the characteristics. In recent years, for this purpose, a high-output, linear-beam excimer laser corresponding to a large-diameter glass substrate has been developed.

[0006]

[Problems to be solved by the invention] However, laser
-Polycrystalline silicon obtained by melt crystallization by irradiation
Not only beam energy density but also beam profiling
And amorphous silicon film surface conditions.
It's easy. Therefore, a wide area can be covered on a large-diameter glass substrate.
As a result, polycrystalline silicon with a large grain size is formed uniformly
It was difficult to do.

FIGS. 6A and 6B are graphs for evaluating the crystallinity of silicon in a glass substrate. FIG.
(A) is a graph showing the peak wave number when irradiated with high energy, and FIG. 6 (b) is a graph showing the peak wave number when irradiated with relatively low energy. FIG.
The horizontal axes of (a) and FIG. 6 (b) both indicate the position of the polycrystalline silicon formed on the glass substrate, and the vertical axes both indicate the peak wave number. 480c of amorphous silicon (α-Si)
It has a broad peak near m ^-1 and single crystal silicon (c-
Si) has a peak at 520.5 cm ^-1 , and polycrystalline silicon (p-Si) has an intermediate peak. Polycrystalline silicon formed by excimer laser has a correlation that a higher peak wavenumber facilitates obtaining a current carrier with higher mobility.

[0008] Under the condition of relatively low laser energy, as shown in FIG.
That is, although the variation in the crystal grain size is small, the peak wave number is low, that is, only a crystal having a small crystal grain size can be obtained. Therefore, even if the polycrystalline silicon obtained under these conditions is used, a TFT having a high response speed cannot be manufactured.
On the other hand, under the condition of relatively high energy, as shown in FIG. 6A, there is a portion having a high peak wave number as shown in FIG. 6A, and polycrystalline silicon having a large crystal grain size is obtained. I understand. However, as shown in the figure, there is a place where the peak wave number is low, which indicates that the variation in the crystal grain size is large. In addition, the irregularities on the surface of the obtained polycrystalline silicon are large. The large variation in crystallinity is due to the influence of laser power fluctuation and beam edge.

As described above, in the prior art, polycrystalline silicon having a large crystal grain size cannot be uniformly obtained over a wide range by irradiating an amorphous silicon film on a glass substrate with laser light. The response speed of a TFT or a driver IC depends on the size of the crystal grains of polycrystalline silicon as an active layer, and the larger the crystal grains, the faster the response speed. Therefore, according to the conventional technology, the response speed of the TFT and the driver IC varies widely, and the T
There is a problem that FTs and driver ICs cannot be manufactured on a glass substrate with good yield.

The present invention has been made in view of the above problems, and provides a method of manufacturing a semiconductor capable of forming uniform and large crystal grains in active regions of a large number of transistors on a glass substrate. It is an object to provide a semiconductor device.

[0011]

In order to solve the above-mentioned problems, the present invention provides, in order from the bottom, a pattern of a non-single-crystal silicon film and a light-transmitting insulating film on an insulating substrate; Forming a structure in which a pattern of a metal film having an area smaller than the area of the pattern is laminated, and using the pattern of the metal film as a mask and the pattern of the insulating film to form a laser on the non-single-crystal silicon film. Irradiating light and heating to melt a part of the non-single-crystal silicon film; and expanding a melting region of the non-single-crystal silicon film by heat conduction to form the non-single-crystal silicon film under the metal film pattern. A step of melting the crystalline silicon film; and a step of cooling and crystallizing the melted non-single-crystal silicon film to form polycrystalline silicon.

As described above, in the present invention, instead of obtaining polycrystalline silicon having a uniform crystal grain size over the entire non-single-crystal silicon film and having a large size, characteristics are affected by the size of the crystal grain. It is an object of the present invention to obtain a polycrystalline silicon film having a uniform crystal grain size and a large area only in a region. According to the present invention, a structure in which a pattern of an insulating film and a pattern of a metal film having an area smaller than the pattern of the insulating film are stacked from the bottom on a non-single-crystal silicon film, that is, a so-called stepped shape is formed. I have. Then, the non-single-crystal silicon film is melted by irradiating laser light in this step shape. At this time, the laser light passes through the pattern of the insulating film and reaches the non-single-crystal silicon film. In this case, the laser energy can be used more efficiently by giving the function of the antireflection film to the pattern of the insulating film.

That is, the non-single-crystal silicon film is irradiated with laser light in a region below the pattern of the insulating film outside the pattern of the metal film. I can do it. Also,
The non-single-crystal silicon film immediately below the metal film pattern is not irradiated with the laser light, but can be melted by increasing the temperature by heat diffusion (thermal conduction) from a region outside the metal film pattern. At this time, the temperature distribution of the non-single-crystal silicon film is such that, in a region immediately below the metal film pattern, the temperature is outside the metal film pattern and lower than the region below the insulating film pattern.

When this is cooled, the pattern of the metal film has a high thermal conductivity, so that the cooling rate of the non-single-crystal silicon film immediately below the pattern of the metal film is high. On the contrary,
Since the thermal conductivity of the insulating film pattern is low, the cooling rate of the non-single-crystal silicon film below the insulating film pattern is low. Therefore, crystallization proceeds from the central portion below the pattern of the metal film toward both outer sides.

Thus, a desired region of the non-single-crystal silicon film on the insulating substrate has a uniform crystal grain size in a self-aligned manner,
In addition, it can be converted to large polycrystalline silicon. Therefore, by forming the staircase shape in a region where a large number of transistors are formed on the insulating substrate, the polycrystalline silicon having a high mobility of the current carrier, particularly only in the active layer, can be uniformly spread over a wide range. Can be formed.

When the above method is applied to the fabrication of a transistor, for example, a metal film pattern is used as a gate electrode, an underlying insulating film pattern is used as a gate insulating film, and a polycrystalline silicon film thereunder is used as a channel region of the transistor. Then, one crystal grain is formed in the channel region in the channel length direction. At this time, when the channel width extending in the direction intersecting with the channel length direction is wide, a plurality of crystal grains are arranged in the channel width direction. As described above, there is only one crystal having a large grain size in the channel length direction, and the crystal grains continue in the channel width direction to form a channel region. Therefore, since there is no grain boundary between crystals in the direction of the channel length, the mobility of the current carrier is increased, and other characteristics such as the response speed of the transistor can be improved.

Further, by forming the step-like shape in a region where a large number of transistors are formed on an insulating substrate, a high-performance transistor having characteristics close to a transistor using single crystal silicon as an active layer can be obtained. It can be formed with good yield on an insulating substrate having a large diameter. Further, a liquid crystal panel integrated with a drive circuit can be easily manufactured on an insulating substrate.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1A is a sectional view showing a semiconductor device according to a first embodiment of the present invention, and FIG. 1B is a plan view. FIG. 1 (a) is a sectional view taken along the line IV-IV in FIG.
FIG.

As shown in FIG. 1A, a glass substrate 10
P-Si film pattern 14, SiO ₂
Metal film pattern 18 composed of film pattern 16a and Mo
a is formed. The SiO ₂ film pattern 16a is made of Si
O ₂ is formed smaller than the area of the p-Si film pattern 14b formed below the film pattern 16a. Also, S
The metal film pattern 18a formed on the iO ₂ film pattern 16a is formed smaller than the area of the SiO ₂ film pattern 16a.

That is, the a-Si film pattern 14, the SiO ₂ film pattern 16a, and the metal film pattern 18a are formed in a so-called stepped shape from the bottom. Here, the p-Si film pattern 14b is an active layer of the transistor, the SiO ₂ film pattern 16a is a gate insulating film, and the metal film pattern 18a is a gate electrode. p-S
The i-film pattern 14b has a source 15b and a drain 15
a is formed. One crystal grain (grain) is formed in the direction of the channel length between the source 15b and the drain 15a, and a plurality of grains are arranged in a direction intersecting the channel length to form a channel portion of the transistor.

According to the semiconductor device of this embodiment, there is only one p-Si crystal grain in the direction of the channel length of the transistor. That is, since there is no crystal grain boundary in the direction of the channel length, the mobility of the current carrier can be improved. Therefore, transistor characteristics such as the response speed of the transistor can be improved.

(Second Embodiment) FIGS. 2A to 2D
2 are cross-sectional views for explaining a method of manufacturing a semiconductor device according to the second embodiment of the present invention in the order of steps.
The drawings on the right side of (a) to (c) are plan views. FIG.
The cross-sectional views on the left side of (a) to (c) are V- in the plan view on the right side.
5 shows a section along V, VI-VI and VII-VII. In the method of manufacturing a semiconductor device according to the second embodiment, the p-Si film pattern 14d is formed by patterning the a-Si film 14c and then melting and crystallizing the same.
That the SiO ₂ film pattern 16b for transmitting the laser light on the Si film pattern 14c and the metal film pattern 18b for reflecting the laser light are left as they are and used as the gate insulating film and the gate electrode, respectively. Features.

As shown in FIG. 2A, first, PE-C
By VD (Plasma enhanced chemical vapor deposition), SiO ₂ and amorphous silicon (hereinafter referred to as a-Si) as non-single-crystal silicon are continuously grown on a glass substrate 10 a as an insulating substrate in order from the bottom, A base SiO ₂ film 12a and an a-Si film are formed respectively. The thickness of the a-Si film is, for example, 50 nm. In addition,
A glass substrate 10a coated with silica may be used.

Next, a resist film (not shown) is patterned on the a-Si film by photolithography,
Using this as a mask, the a-Si film is patterned into an island shape to form an a-Si film pattern 14c. Next, FIG.
As shown in (b), a 50 nm thick SiO ₂ film is formed on the a-Si film pattern 14c by the CVD method, and a 300 nm Mo film is formed on the SiO ₂ film 12a by sputtering.
m is formed. A resist film (not shown) is patterned by photolithography so as to be smaller than the area of the a-Si film pattern 14c, and using this as a mask, the Mo film is etched to form a gate electrode 18b. The width of the gate electrode 18b is preferably 2 μm or less, for example, 0.8 μm.

Next, as shown in FIG. 2B, a resist film (not shown) is formed by a-S by photolithography.
Patterning is performed so that the area is smaller than the area of the i-film pattern 14c and larger than the gate electrode 18b, and the SiO ₂ film is etched using the mask as a mask to form the gate insulating film 16b. Thereby, the a-Si film pattern 14c, the gate insulating film 16b, and the gate electrode 18b
Are formed so as to form a step shape from the bottom in order.

Next, the temperature of the glass substrate 10a is maintained at room temperature.
Pulse width from 40 ns to several hundred ns
ec pulsed ultraviolet laser, for example, Xe-Cl
Using excimer laser (wavelength 308nm),
Energy density about 350mJ / cm ^TwoOn the glass substrate 10a
Is irradiated on the a-Si film pattern 14c. Pulsed purple
The use of an external laser affects the glass substrate 10
This is for heating the a-Si film 14c without giving it.

Next, referring to FIGS. 3 and 4, the a-Si film pattern 14c when excimer laser light is irradiated
The state of conversion from a to a p-Si film (polycrystalline silicon film) 14d will be described in detail. FIG. 3 is a cross-sectional view showing a state where the sample is irradiated with laser light after the step shown in FIG. 2B is completed. That is, FIG. 2C is enlarged.

FIG. 4 is a graph showing a temperature distribution when the a-Si film 14c shown in FIG. 3 is irradiated with excimer laser light. A region A in FIG. 4 is a gate electrode 18b made of Mo.
Shows the temperature distribution of the a-Si film pattern 14c below
The region and the C region show the temperature distribution of the a-Si film pattern 14c under the gate insulating film 16b on both sides outside the metal film pattern 18b. Further, the D region and the E region show the temperature distribution in a portion where the a-Si film pattern 14c on both sides outside the gate insulating film 16b is exposed.

The gate electrode 18b is made of Mo that reflects laser, and a gate insulating film 16b formed with a thickness that minimizes laser reflection is formed under the gate electrode 1b.
8b. As shown in FIG. 3, when the laser light is irradiated, the laser light
b and the underlying a-Si film pattern 14
does not reach c. On the other hand, since the gate insulating film 16b is translucent, the laser reaches the underlying a-Si film pattern 14c. When the laser beam is irradiated, the temperature of the region A also increases due to the diffusion of heat from the region B and the region C. At this time, the a-Si film pattern 14 under the gate electrode 18b
In the region A of c, the temperature is lower than those in the regions B and C because the laser light is not directly received in the region A. The reason why the temperatures of the D region and the E region are lower than those of the B region and the C region is that the incident state and the heat radiation state are different.

By irradiating the laser beam in this manner, the a-Si film pattern 14c is melted throughout the a-Si film pattern 14c while maintaining the temperature distribution as shown in FIG. Thereafter, when the pulse of the laser beam ends, the melted a-Si film pattern 14c is cooled and crystallized. Here, the cooling rates of the region A, the region B, and the region C are different. This is because the gate electrode 18b having high thermal conductivity is located above the region A, and the gate insulating film 16b having low thermal conductivity is located above the regions B and C.
This is because the heat radiation state is different. That is, in the region A, the cooling speed is high because the heat easily escapes, and the cooling speed is low because the heat is hard to escape in the upper portions of the regions B and C. Therefore,
The temperature distribution in FIG. 4 changes so that the temperature difference between the region A and the regions B and C increases.

As a result, as shown in FIG. 3, crystallization of the molten a-Si film pattern 14c proceeds from the region A to the regions B and C. That is, the metal film putter 1
Crystallization proceeds from the center of the lower part of 8b toward the outside of both sides in the short direction of the metal film pattern 18b. Accordingly, the entire width of the gate electrode 18b in the lateral direction is 0.8 μm.
A single grain can be grown to an extent. On the other hand, one crystal grain is formed so as to be continuous in the longitudinal direction of the gate electrode 18b. In this way,
The p having a large crystal grain size is locally formed under the gate electrode 18b.
-The Si film pattern 14d can be obtained.

In this manner, a channel portion having only one crystal grain formed in the direction of the channel length is formed on the gate electrode 18b.
Can be formed in a self-aligned manner. Next, using the gate electrode 18b as a mask, a conductive impurity such as phosphorus is implanted into the p-Si film 14d by an ion doping method or the like. Subsequently, annealing is performed to activate the conductive impurities to form the source 15b and the drain 15a.
This ion doping method is a method of implanting all generated ionic species of conductive impurities without mass separation. As a result, hydrogen in the plasma is also implanted at the same time, and the ion current density increases, so that the p-Si film 14 d
Temperature rises. Therefore, since the crystallinity of the p-Si film 14d is maintained, a conductive type impurity such as phosphorus can be activated at a low temperature annealing, for example, at a temperature of 300 ° C.

In the case of a lightly doped drain (LDD) structure, first, a conductive impurity such as low-concentration phosphorus is implanted into the p-Si film pattern 14d at an acceleration energy that penetrates the gate insulating film 16b. afterwards,
The gate insulating film 16 b
Is a p-Si film pattern 1 with acceleration energy used as a mask
Inject into 4d.

As a result, the source 15b and the drain 15a are formed in a self-aligned manner, and a transistor having an LDD structure with a small element size and a small parasitic capacitance can be easily formed on the glass substrate 10a. Next, FIG.
As shown in (d), a cover SiO ₂ film 24 is formed by the CVD method, and subsequently, a contact window of the drain 15a is opened by photolithography and etching. Then, a film of ITO (indium tin oxide) is formed by sputtering, and the pixel electrode 26 is formed by patterning the ITO by photolithography and etching.

Next, a contact window of the source 15b is formed in the cover SiO ₂ film 24 by photolithography and etching. Then, a film of Al is formed by sputtering, and Al is patterned by photolithography and etching to form a source electrode 28. Thus, the semiconductor device of FIG. 1 is completed.

According to the second embodiment, the gate insulating film 16b and the gate electrode 18b are formed in a step shape on the a-Si film pattern 14c on the large-diameter glass substrate 10a, and the laser beam is irradiated. Thereby, a channel portion in which only one crystal grain is formed in the channel length direction can be formed in a self-aligned manner with respect to gate electrode 18b.

Therefore, there is no need to align the gate electrode 18b with the channel. Therefore, the gate electrode 18
Since the width in the lateral direction of b can be reduced, the channel length can be easily reduced. Thus, characteristics such as the response speed of the transistor can be improved. In addition, by forming the step shape in a region where a large number of transistors are formed on the glass substrate 10a, it is possible to uniformly form polycrystalline silicon having a high current carrier mobility especially in the active layer. it can.

Accordingly, a high-performance transistor can be manufactured on a large-diameter glass substrate with high yield.
The TFT and the driver IC can be formed at the same time. Since the TFT and the driver IC can be formed at the same time, a liquid crystal panel integrated with a driving circuit can be easily manufactured. In addition, the a-Si film is etched into an island shape in advance to form the a-Si film pattern 14c, and then the laser light is irradiated. Therefore, a-Si
Since the heat radiation from the film pattern 14c is small, the a-Si film pattern 14c can be efficiently used with a low energy laser beam.
Can be melted to obtain crystals. Also, a plurality of a
Since the temperature difference between the -Si film patterns 14c can be reduced, a uniform p-Si film is formed on the glass substrate 10a.
A plurality of p-Si film patterns 14 having crystal grains 17b can be obtained over a wide range.

In this embodiment, the conductive type impurity is implanted into the source and the drain after the laser irradiation, and then the activation annealing of the conductive type impurity is performed.
Before the laser irradiation process, the source 15b and the drain 1
A conductive impurity may be implanted into 5a, and melting of the a-Si film pattern 14c and activation of the conductive impurity may be simultaneously performed by laser light irradiation. The energy density of the laser at this time is, for example, 350 mJ / cm ^{2 for} the melting energy density of the a-Si film pattern 14c. In general, when the purpose is only activation of impurities, 250 mJ / cm
^{2 to} 280 mJ / cm ² .

(Third Embodiment) FIGS. 5A to 5D
5A to 5C are cross-sectional views illustrating a method of manufacturing a semiconductor device according to a third embodiment of the present invention in the order of steps, and FIGS.
The drawing on the right side of (d) is a plan view. FIG.
Sectional views of (d) are II-II and II-I of the same plan view, respectively.
3 shows a section along I and III-III.

The difference from the second embodiment is that a-Si
After the film 14 is melted and crystallized without patterning, the p-Si film is patterned and
Removing the SiO ₂ film pattern 16a for transmitting the laser light on the Si film pattern 14b and the metal film pattern 18a for reflecting the laser light, newly forming the gate insulating film 13 and the gate electrode 18c; It is that you are.

First, as shown in FIG. 5A, a base SiO ₂ film 12, an a-Si film 14, and a SiO ₂ film 16 are formed in this order on a glass substrate 10, which is an insulating substrate.
The thickness of the a-Si film 14 is, for example, 50 nm. SiO
The thickness of the _second film 16 is set to a thickness that becomes an anti-reflection film for laser light, for example, 50 nm. After that, SiO ₂
On the film 16, Mo (molybdenum) is formed by sputtering to a thickness of 20 nm to form a metal film 18.

Next, as shown in FIG. 5B, a resist film (not shown) is patterned by photolithography, and the metal film 18 is etched using the resist film as a mask to form a metal film pattern 18a. Form. a-
When the Si film 14 is melted by the laser beam, the a-Si film 14 immediately below the metal film pattern 18a is
Is melted from the lower a-Si film 14 on both sides outside, that is, from the left and right, so that the width W of the a-Si film 14 that can be melted at a temperature that the glass substrate 10 can withstand is limited to about 2 μm. is there. Therefore, the metal film pattern 1
The width W of 8a is preferably 2 μm or less.

Next, by photolithography, to cover the metal film pattern 18a, and then patterned larger than the resist film (not shown) the area, which the SiO ₂ film 16 is etched as a mask, SiO ₂ A film pattern 16a is formed. The metal film pattern 18a
Dimension W where the SiO ₂ film pattern 16a protrudes laterally from
a is preferably smaller than 3 μm.

As a result, the SiO ₂ film pattern 16a and the metal film pattern 18 having an area smaller than the SiO ₂ pattern 16a are formed on the a-Si film 14 in this order from the bottom.
a, a so-called stepped shape can be formed. Next, a pulse width of 40 n is applied to the entire surface of the glass substrate 10.
The pulsed ultraviolet laser is irradiated for a few seconds to several hundreds of nanoseconds to convert the a-Si film 14 into a polycrystalline silicon film (hereinafter, referred to as a polycrystalline silicon film).
p-Si). Xe as UV laser
Using a -Cl excimer laser (wavelength 308 nm), the energy density is about 350 mJ / cm ² . At this time, since the a-Si film 14, the SiO ₂ film pattern 16a, and the metal film pattern 18a are formed in a so-called stepped shape, the metal film pattern 18a reflects laser light as in the second embodiment. Then, only the region of the SiO ₂ film pattern 16a on both sides outside the metal film pattern 18a transmits the laser beam, and the temperature of the a-Si film 14 thereunder rises.

Then, a below the metal film pattern 18a
The temperature of the -Si film 14 rises due to thermal diffusion from the side and is melted over the entire a-Si film 14. This is cooled, and crystallization proceeds from the center of the metal film pattern 18a toward both outer sides. Thereby, one crystal grain can be grown over about 2.0 μm, which is the entire width of the metal film pattern 18a in the lateral direction. On the other hand, metal film pattern 1
One crystal grain is formed so as to be continuous in the longitudinal direction of 8a. In this manner, the p-Si film 14a having a locally large crystal grain size under the metal film pattern 18a can be obtained.

Next, the metal film pattern 18a and SiO ₂
After removing the film pattern 16a, as shown in FIG. 1D, a mask of a resist film (not shown) is formed on the p-Si film 14a by photolithography, and according to the mask, the p-Si film 14a is formed. Is etched and p-S
An i-film pattern 14b is formed. This p-Si film pattern 14b is formed in large numbers on the glass substrate 10, and can be used as an active layer of a transistor.

Next, C is deposited on the p-Si film pattern 14b.
A gate insulating film 13 made of a silicon oxide film is formed by a VD (chemical vapor deposition) method. continue,
An Al film is formed on the gate insulating film 13 by a sputtering method. Next, a mask of a resist film (not shown) is formed on the Al film by photolithography. At this time, the exposure mask having the gate patterns of the plurality of transistors is adjusted so that the longitudinal width of the large crystal grains formed in the p-Si film pattern 14b becomes the gate length of the transistor, that is, the channel length. Then, the resist film is patterned by exposing and developing. Subsequently, using this resist film as a mask, the Al film is etched to form a gate electrode 18c.

Next, a conductive type impurity such as phosphorus is introduced by a known method to form a source and a drain.
A transistor such as an FT is formed. As described above, FIG.
Is completed. According to the third embodiment, a large number of steps are formed in a region where a predetermined transistor is formed on the glass substrate 10 and a laser beam is applied to the region to form a-Si. Membrane 14
The desired region, that is, the region for forming the transistor of the a-Si film 14 can be converted to the p-Si film 14a. Further, since the laser is irradiated while the a-Si film 14 is covered with the SiO ₂ film pattern 16a,
The p-Si film 14 having good flatness can be obtained.

That is, by forming the staircase shape in a region where a large number of transistors are formed on an insulating substrate, polycrystalline silicon having a current carrier mobility close to that of a single crystal, particularly only in its active layer, is obtained. Can be formed uniformly and flatly over a wide range. In the p-Si film pattern 14b in the region where each transistor is formed, there is a region in which a plurality of large crystal grains are formed in series, and the width of one crystal grain in the longitudinal direction becomes the channel length of the transistor. Thus, a transistor is formed. Accordingly, since there is no crystal grain boundary in the channel length of the transistor, a transistor having a response speed equivalent to that of a transistor using a single crystal as an active layer can be easily formed on the glass substrate 10. .

Accordingly, it has a response speed close to that of a transistor having a single crystal as an active layer on a large-diameter glass substrate 10.
High-performance transistors can be formed with high yield. A TFT and a driver I are mounted on a large-diameter glass substrate.
Since C and C can be simultaneously formed, a liquid crystal panel integrated with a drive circuit can be easily manufactured. The above-described embodiments are merely examples in all aspects and should not be construed as limiting. The present invention can be implemented in various other forms without departing from the gist thereof. The scope of the present invention is defined by the claims, and is not limited by the embodiments.

(Supplementary Note 1) On the insulating substrate, in order from the bottom, a pattern of a non-single-crystal silicon film and a pattern of a light-transmitting insulating film, and a pattern of a metal film having an area smaller than the area of the pattern of the insulating film. Forming a structure in which the non-single-crystal silicon film is stacked, and irradiating the non-single-crystal silicon film with a laser beam and heating through the pattern of the metal film and the pattern of the insulating film, thereby heating the non-single-crystal silicon. Having a step of melting a part of the film, expanding a melting region of the non-single-crystal silicon film by heat conduction, and melting the non-single-crystal silicon film under the pattern of the metal film, A method for manufacturing a semiconductor device, wherein a molten non-single-crystal silicon film is cooled and crystallized to form polycrystalline silicon.

(Supplementary Note 2) The semiconductor according to Supplementary Note 1, wherein the insulating substrate is a glass substrate other than quartz glass, or a silicon-containing insulating film is formed on the glass substrate. Device manufacturing method. (Supplementary Note 3) The method for manufacturing a semiconductor device according to Supplementary Note 1, wherein the width of the pattern of the metal film is 2 μm or less.

(Supplementary Note 4) The method of manufacturing a semiconductor device according to any one of Supplementary Notes 1 to 3, wherein the pattern of the insulating film is an antireflection film for the laser beam. (Supplementary Note 5) Before the step of irradiating the non-single-crystal silicon film with laser light and heating, the method includes a step of introducing a conductive impurity into the non-single-crystal silicon film using the pattern of the metal film as a mask, The method according to any one of supplementary notes 1 to 4, wherein the step of irradiating the non-single-crystal silicon film with a laser beam and heating the non-single-crystal silicon film and activating the conductive impurities together with the melting of the non-single-crystal silicon film. The manufacturing method of the semiconductor device described in the above.

(Supplementary Note 6) The polycrystalline silicon film is an active layer of a transistor in which a channel region is below a pattern of the metal film and both sides of the pattern of the metal film are source / drain regions. 6. The method of manufacturing a semiconductor device according to claim 1, wherein the pattern of the insulating film is a gate insulating film, and the pattern of the metal film is a gate electrode.

(Supplementary Note 7) An insulating substrate, a polycrystalline silicon film formed on the insulating substrate, and a region formed on the polycrystalline silicon film and smaller than a region where the polycrystalline silicon film is formed. A semiconductor device having a pattern of a light-transmitting insulating film having an area, and a pattern of a metal film having an area smaller than the area of the pattern of the insulating film formed on the pattern of the insulating film, The polycrystalline silicon film is an active layer of a transistor in which a channel region is below a pattern of the metal film and both sides of the pattern of the metal film are source / drain regions. Is a gate insulating film, the pattern of the metal film is a gate electrode, and the polycrystalline silicon under the pattern of the metal film has a single crystal grain in a channel length direction. A semiconductor device, comprising:

(Supplementary Note 8) The semiconductor device according to supplementary note 7, wherein the length of the crystal grain is 2 μm or less.

[0058]

As described above, a structure in which a pattern of a light-transmitting insulating film and a pattern of a metal film having an area smaller than the pattern of the insulating film are laminated on the non-single-crystal silicon film in this order from the bottom. A so-called stepped shape. Then, laser light is irradiated through the pattern of the insulating film in this step shape, and the entire non-single-crystal silicon film is melted. When this is cooled, due to the difference in thermal conductivity between the pattern of the metal film and the pattern of the insulating film,
Crystallization proceeds from the central portion below the metal film pattern to both outer sides. Thus, a desired region of the non-single-crystal silicon film on the insulating substrate can be converted into polycrystalline silicon having a uniform crystal grain size and a large size in a self-aligned manner.

That is, by forming the staircase shape in a region where a large number of transistors are formed on the insulating substrate, polycrystalline silicon having a high current carrier mobility can be formed over a wide range, particularly only in the active layer. It can be formed uniformly. Therefore, a high-performance transistor can be formed on a large-diameter insulating substrate with high yield. Further, a liquid crystal panel integrated with a drive circuit can be easily manufactured on an insulating substrate.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view illustrating a semiconductor device according to a first embodiment, FIG. 1B is a plan view of the same,
(A) corresponds to a cross-sectional view taken along line IV-IV of (b).

FIGS. 2A to 2D are a cross-sectional view and a plan view illustrating a method of manufacturing a semiconductor device according to a second embodiment in the order of steps; FIGS.

FIG. 3 is an enlarged cross-sectional view of FIG. 1C, showing a state where an a-Si film is melted by laser irradiation.

FIG. 4 is a diagram showing a temperature distribution of an a-Si film in FIG.

5A to 5D are a cross-sectional view and a plan view illustrating a method of manufacturing a semiconductor device according to a third embodiment in the order of steps.

FIG. 6 is a graph showing a state of crystallization by laser irradiation of the related art over a plane.

[Explanation of symbols]

Reference Signs List 10 glass substrate, 12 base SiO ₂ film, 14 a-Si film, 14 ba a-Si film pattern, 15 a drain, 15 b source, 16 SiO ₂ film, 16 a SiO ₂ film pattern, 16 b gate insulating film, 17 a, 17 b crystal grains 18 metal film, 18a metal film pattern, 18b gate electrode, 24 cover SiO ₂ film, 26 pixel electrode, 28 source electrode.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) PP23 PP27 QQ11

Claims (3)

[Claims] 1. A pattern of a non-single-crystal silicon film and a pattern of a light-transmitting insulating film, and a pattern of a metal film having an area smaller than the area of the pattern of the insulating film, on the insulating substrate in order from the bottom. Forming a stacked structure, and using the pattern of the metal film as a mask, and through the pattern of the insulating film, irradiating the non-single-crystal silicon film with laser light and heating the non-single-crystal silicon film. Melting a portion of the non-single-crystal silicon film by heat conduction, melting the non-single-crystal silicon film below the pattern of the metal film, and then melting the non-single-crystal silicon film. A method for manufacturing a semiconductor device, wherein a non-single-crystal silicon film is cooled and crystallized to form polycrystalline silicon. 2. A step of introducing a conductive impurity into the non-single-crystal silicon film using the pattern of the metal film as a mask before the step of irradiating the non-single-crystal silicon film with a laser beam and heating. 2. The semiconductor device according to claim 1, wherein in the step of irradiating the non-single-crystal silicon film with a laser beam and heating the non-single-crystal silicon film, the non-single-crystal silicon film is activated together with melting of the non-single-crystal silicon film. Production method. 3. An insulating substrate, a polycrystalline silicon film formed on the insulating substrate, and an area smaller than a formation region of the polycrystalline silicon film formed on the polycrystalline silicon film. A semiconductor device comprising: a light-transmitting insulating film pattern having a pattern; and a metal film pattern formed on the insulating film pattern and having a smaller area than the insulating film pattern. The crystalline silicon film is an active layer of a transistor in which a channel region is below a pattern of the metal film and both sides of the pattern of the metal film are source / drain regions, and the pattern of the insulating film is a gate. An insulating film, wherein the pattern of the metal film is a gate electrode, and polycrystalline silicon below the pattern of the metal film has one crystal grain in a channel length direction. The semiconductor device according to claim.