JPH11283922A - Manufacture of semiconductor device and the semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an element having good characteristics, without conducting highly accurate heating control by implanting in an Si substrate an element, which does not behave as a donor or acceptor in the Si film formed on a substrate and masks the Si film amorphous, the forming the element of a polysilicon film which is obtained by heating. SOLUTION: An amorphous Si film 103 is deposited on a insulation film 102 formed on a substrate 101, Ar ion 104 is implanted which does not behave as a donor or acceptor in the amorphous Si film does not form an Si compound but makes the Si film amorphous, thereby cutting in pieces the fine networks in Si forming the amorphous film 103, then laser annealing is applied to crystallize the amorphous Si film, thereby obtaining a polysilicon film 106, and the element is formed by the use of the polysilicon film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a semiconductor film such as a polysilicon film or an amorphous silicon film on a substrate such as a glass substrate or a quartz substrate, and performing a heat treatment process such as a laser annealing process. It belongs to the technical field of a method of manufacturing a semiconductor device to be formed.

[0002]

2. Description of the Related Art Conventionally, in a method of manufacturing a semiconductor device of this kind, for example, an insulating film serving as a base film is formed on a glass substrate as
An iO ₂ (silicon oxide) film is formed, and an amorphous amorphous silicon film is formed on the SiO ₂ film under reduced pressure CVD (Chemic
al Vapor Deposition (chemical vapor deposition), and a polysilicon film is formed by crystallizing the amorphous silicon film by a heat treatment process such as a laser annealing process, a solid phase growth process, and a lamp annealing process. Then, by doping a predetermined amount of a donor or an acceptor into the polysilicon film, a channel forming region, a source region, a drain region, and the like are formed. Further, a thin film transistor is formed by forming a gate insulating film, a gate electrode, a source electrode, a drain electrode, an interlayer insulating film, and the like, and a semiconductor device including the thin film transistor is manufactured.

In such a manufacturing method, semiconductor devices are generally mass-produced. However, with respect to thin film transistors constituting each semiconductor device, transistor characteristics such as threshold characteristics and voltage-current characteristics are improved (for example, a threshold voltage). It is important to maintain a constant quality as well as high quality and to produce a standardized product with high quality and stable quality (constant). In particular, when a semiconductor device is manufactured by forming a large number of thin film transistors on a large substrate, it is important to keep the transistor characteristics of a plurality of thin film transistors on the same substrate constant. In an active matrix drive type display panel such as an EL (electroluminescence) panel or a liquid crystal panel in which the thin film transistor is formed for driving a pixel, the above-described variation in transistor characteristics causes density unevenness among a plurality of pixels. It is important to keep the transistor characteristics constant.

[0004]

However, in the above-mentioned conventional method, the crystallization of the polysilicon film is greatly affected by the degree of heating in the heat treatment step such as laser irradiation energy (or laser wavelength) in the laser annealing treatment. . Therefore, the transistor characteristics of the thin film transistor finally obtained respond very sensitively to this degree of heating. That is, when a specific laser irradiation energy is set to, for example, 380 mJ / cm ² and laser annealing is performed, this energy is 38 due to variations in the characteristics of the irradiation apparatus and changes in the operating environment such as the operating temperature.
When the deviation is about 0 ± 10 mJ / cm ² , the crystallization variation of the polysilicon film formed through the laser annealing becomes large, and the threshold voltage of the thin film transistor is designed within a range of about several volts. That is a big departure from the value.

As a result, unless the laser irradiation energy at the time of laser annealing is controlled with extremely high precision in practice, for example, about 380 ± several mJ / cm ² , a thin film transistor having constant transistor characteristics cannot be obtained. . That is, it is extremely difficult to manufacture a semiconductor device including a thin film transistor or the like having a certain transistor characteristic by using a standard laser irradiation device or the like that is currently widely used, and the manufactured semiconductor device malfunctions or becomes inoperable. There is a problem that the non-defective product rate becomes high.

Further, in the above-mentioned conventional method, characteristics of a semiconductor element such as a transistor characteristic of a thin film transistor in a semiconductor device to be manufactured are too small due to, for example, insufficient crystallization of a polysilicon film. It is not expensive and has room for improvement.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a method of manufacturing a semiconductor device capable of forming a semiconductor element such as a thin film transistor having constant and favorable characteristics on a substrate relatively easily, and the semiconductor device. The task is to provide

[0008]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a silicon film on a substrate; and forming a donor or an acceptor in the silicon film. An implantation step of injecting a predetermined amount of an element capable of amorphizing the silicon film into the silicon film without acting as, and crystallizing the element by applying heat to the silicon film into which the element has been implanted. And a device forming step of forming a semiconductor device using the polysilicon film.

According to the method of manufacturing a semiconductor device according to the first aspect, first, in a film forming step, a silicon film is formed on a substrate by CVD or the like. Next, a predetermined amount of an element which does not act as a donor or an acceptor in the silicon film, does not generate a silicon compound, and can amorphize the silicon film is implanted into the silicon film by an implantation step. Injected. Then, the silicon film becomes at least partially amorphous or a fine network in the silicon is divided. Thereafter, heat is applied to the silicon film into which the element has been implanted by a heat treatment step, so that the silicon film is crystallized and a polysilicon film is formed on the substrate. Then, in a device forming step, a semiconductor device is formed using the polysilicon film.

Here, according to the study by the present inventors,
As compared with the case where the heat treatment is performed in the above-described conventional manufacturing method, the device characteristics such as the threshold voltage characteristic and the current-voltage characteristic of the semiconductor element formed in the element formation step in this way are different from those of the silicon film in the heat treatment step It reacts insensitively to the degree of heating. This phenomenon is caused by the fact that (i) a fine network in silicon in the polysilicon film is divided and homogenized by the implantation of the aforementioned elements in the implantation step, and (ii) the interface between the substrate and the silicon film is (Iii) the heat capacity of the silicon film changes and the crystallization by the heat treatment progresses uniformly, and the heat treatment is performed. It is considered that the crystallization of the polysilicon film is not significantly affected by the degree of heating during the process. However, in any case, the device characteristics of the semiconductor device formed in the device forming process according to the present invention depend on the heat treatment. It reacts insensitively to the heating degree of the silicon film in the process. For example, in the case of performing a laser annealing process while setting the laser irradiation energy to a low value in the heat treatment process, the energy may be ± 10 mJ / cm ² due to variations in the characteristics of the irradiation device and changes in the operating environment such as the operating temperature. Even if it is shifted to the extent, the threshold voltage of the thin film transistor formed through the laser annealing is kept almost constant. As a result, a semiconductor device having constant device characteristics can be obtained without controlling the degree of heating in the heat treatment step with high accuracy, such as laser irradiation energy during laser annealing. In addition, since the crystallization proceeds uniformly in the heat treatment performed after the implantation step as described above, the characteristics itself of the semiconductor element formed are also improved.

According to a second aspect of the present invention, in the method of manufacturing a semiconductor device according to the first aspect, the element includes at least one of an inert gas element, silicon, and a halogen element. It is characterized by including.

According to the method of manufacturing a semiconductor device of the present invention, Ar (argon), Kr
(Krypton), inert gas elements such as Ne (neon) and Xe (xenon), silicon (Si), and Cl (chlorine);
At least one of halogen elements such as Br (bromine) and I (iodine) is injected into the silicon film. Then, by the implantation of such an element, the silicon film becomes at least partially amorphous or a fine network in the silicon is divided. Therefore, a semiconductor device having constant device characteristics can be obtained using the silicon film without controlling the degree of heating in the heat treatment step with high accuracy.

According to a third aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, in the heat treatment step, the solid phase is formed by laser annealing, low-temperature or high-temperature annealing. Growth processing,
In addition, at least one of a lamp annealing process is performed.

According to the method of manufacturing a semiconductor device of the present invention, at least one of a laser annealing process, a solid-phase growth process using low-temperature or high-temperature annealing, and a lamp annealing process is performed in the heat treatment process. A semiconductor with constant and good device characteristics using a polysilicon film crystallized by each heat treatment without having to control the degree of heating in each heat treatment step with high precision, such as laser irradiation energy in laser annealing treatment. An element is obtained.

According to a fourth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the amorphous silicon film as the silicon film is formed in the film forming step. Formed on a substrate, and in the implantation step, as the element Ar,
Injecting 5e13 / cm ² or more as the predetermined amount, and performing laser annealing in the heat treatment step.

According to the method of manufacturing a semiconductor device of the present invention, Ar is injected into the amorphous silicon film formed on the substrate by the film forming step.
3 / cm ² or more, preferably 1e14 / cm ² or more is implanted. Therefore, in the amorphous silicon film, a fine network in silicon is divided. Then, Ar
Heat is applied to the silicon film into which is implanted by laser annealing, so that the silicon film is uniformly crystallized and a polysilicon film is formed on the substrate. Therefore, a semiconductor device having constant and good device characteristics can be obtained using the silicon film without controlling the laser irradiation energy in the laser annealing process with high accuracy.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: forming an amorphous silicon film on a substrate;
Implanting 5e13 / cm ² or more, a heat treatment step of crystallizing the amorphous silicon film into which Ar (argon) has been injected by applying heat to form a polysilicon film, and using the polysilicon film. And an element forming step of forming a semiconductor element.

According to the method of manufacturing a semiconductor device of the present invention, Ar is injected into the amorphous silicon film formed on the substrate by the film forming step.
3 / cm ² or more, preferably 1e14 / cm ² or more is implanted. Therefore, in the amorphous silicon film, a fine network in silicon is divided. Then, Ar
Heat is applied to the silicon film into which is implanted by laser annealing, so that the silicon film is uniformly crystallized and a polysilicon film is formed on the substrate. Therefore, a semiconductor device having constant and good device characteristics can be obtained using the silicon film without controlling the laser irradiation energy in the laser annealing process with high accuracy.

According to a sixth aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to fifth aspects, an amorphous silicon film is formed on the substrate as the silicon film in the film forming step. And a catalyst for promoting crystallization of the amorphous silicon film in the heat treatment step is added to the amorphous silicon film, and in the heat treatment step, a solid phase growth treatment by low-temperature annealing is performed.

According to the method of manufacturing a semiconductor device of the present invention, the film formation step promotes crystallization of the amorphous silicon film in the heat treatment step, and the amorphous silicon film is added with a catalyst such as a metal catalyst such as nickel. A silicon film is formed on the substrate. Therefore, the crystallinity of the amorphous silicon film is improved by the catalyst.
Polysilicon can be formed at a lower temperature and a shorter time, or at a lower temperature or a shorter time, as compared with the case where no catalyst is used. Therefore, a high-quality semiconductor device can be efficiently manufactured as a whole.

According to a seventh aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to sixth aspects, in the film forming step, the substrate is formed of a glass substrate and a glass substrate. And an insulating film formed as a base film, wherein the silicon film is formed on the insulating film.

According to a seventh aspect of the present invention, in the film forming step, a silicon film is formed on an insulating film such as a SiO ₂ film formed as a base film on a glass substrate by CVD or the like. Is formed. Therefore, the contamination of the silicon film from the glass substrate can be prevented by the insulating film, and the physical strength of the substrate can be secured by the relatively inexpensive glass substrate.

According to a eighth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first to seventh aspects, in the element forming step, at least a thin film transistor is formed as the semiconductor element. Features.

According to the method of manufacturing a semiconductor device of the present invention, transistor characteristics such as threshold characteristics and voltage-current characteristics are stable (constant) without controlling the degree of heating in the heat treatment step with high accuracy. And a good thin film transistor can be obtained.

According to a ninth aspect of the present invention, there is provided a method of manufacturing a semiconductor device according to the eighth aspect of the present invention, wherein the thin film transistor is a top-gate type positive stagger type or coplanar type. Features.

According to the method of manufacturing a semiconductor device of the ninth aspect, since the semiconductor device has a top gate structure, the implantation step and the heat treatment step can be relatively easily performed before forming the gate insulating film and the gate electrode in the element forming step. Without having to control the degree of heating in the heat treatment process with high precision.
A positive staggered or coplanar thin film transistor in which transistor characteristics are stable (constant) and favorable is obtained.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a semiconductor device according to the eighth aspect, wherein the thin film transistor is an inverted staggered type having a bottom gate structure. .

According to the method of manufacturing a semiconductor device according to the tenth aspect, since the semiconductor device has a bottom gate structure, a gate electrode and a gate insulating film are formed as a part of an element forming step, and then these gate insulating films and the like are interposed. An implantation process and a heat treatment process are performed on the silicon film formed on the substrate. Accordingly, even if the degree of heating in the heat treatment step is not controlled with high precision, a transistor with stable (constant) transistor characteristics and a favorable inverted staggered thin film transistor can be obtained.

A semiconductor device according to an eleventh aspect is characterized by being manufactured by the method for manufacturing a semiconductor device according to any one of the first to tenth aspects.

According to the semiconductor device of the eleventh aspect,
Since the semiconductor device is manufactured by the above-described method for manufacturing a semiconductor device of the present invention, the semiconductor device is provided with a semiconductor element such as a thin film transistor of a constant quality, and is relatively inexpensive and has a high yield.

The operation and other advantages of the present invention will become more apparent from the embodiments explained below.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) A method for manufacturing a semiconductor device according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a process chart showing the steps in the method of manufacturing a semiconductor device according to the first embodiment in the order of (A) to (J). In the present embodiment, in particular, an N-type TF
The present invention relates to a manufacturing method for forming T and P type TFTs side by side.

First, as shown in FIG. 1A, a TEOS is formed on a transparent glass substrate 101 by plasma CVD.
-O ₂ or SiH ₄ —O ₂ as a material gas, a SiO ₂ film 102 as an example of an insulating film to be a base is about 200 n
m. The SiO ₂ film 102 can prevent the thin film transistor formed thereon from being contaminated by impurities of the glass substrate 101.

Next, low pressure CVD is performed on the SiO ₂ film 102.
And a deposition temperature of about 4 using Si ₂ H ₆ as a source gas.
At 25 ° C., the amorphous silicon film 103 is
Is deposited to a thickness of

Next, as shown in FIG. 1 (B), SiO ₂
Ar ions 104 of about 20 ke are applied to the stacked structure composed of the film 102 and the amorphous silicon film 103 by using an ion implantation apparatus or a non-mass separation type ion implantation apparatus.
5e13 / cm ² or more at an energy of V, preferably
Implant 1e14 / cm ² or more. The substrate temperature during the ion implantation is not particularly limited.

As described above, in the ion implantation step in the present embodiment, an element which does not act as a donor or an acceptor in the amorphous silicon film 103, does not generate a silicon compound, and can make the silicon film amorphous. As an example, a predetermined amount of Ar is injected. Then, a fine network in the silicon forming the silicon film is divided.

In this case, the energy at the time of implanting Ar ions will be described with reference to FIGS. FIG.
Indicates that the energy when implanting Ar ions into an amorphous silicon film (a-Si film) is 10 keV and 20 keV.
FIG. 3 is a table showing the results obtained by calculating the projected range and its standard deviation based on the LSS theory, respectively, in the case of 30 keV, and FIG. 3 shows the amorphous silicon film 103 formed on the SiO ₂ film 102. It is a schematic representation of the projected range and its standard deviation.

As can be seen from the table of FIG. 2, when the energy is 20 keV as in the present embodiment, the projected range of Ar ions is 21 nm, and the standard deviation is 9.7 nm.
It is. Therefore, as shown in FIG. 3, the amorphous silicon film 103 having a thickness of about 50 nm as in this embodiment is used.
The projected range of Ar ions becomes about half of the film thickness of Ar, and the implanted Ar ions peak near the center of the amorphous silicon film 103 in the film thickness direction, and most of the Ar ions are SiO ₂ films. It is implanted into the amorphous silicon film 103 including the interface with 102.

In the ion implantation step shown in FIG. 1B, elements which do not act as donors or acceptors in the silicon film and which can make the silicon film amorphous include Kr (krypton) in addition to Ar. ), Ne (neon), Xe (xenon) and other inert gas elements, silicon (S
and halogen elements such as i), Cl (chlorine), Br (bromine), and I (iodine). However, when Ar ions are implanted as in this embodiment, the amount of Ar remaining in the polysilicon film is as small as about 0.1% by weight, so that a semiconductor film element of the polysilicon film is formed. Ar ions are preferred from the viewpoint of not adversely affecting the properties for the formation.

A polysilicon film is formed by the film forming process shown in FIG. 1A, and Ar is implanted into the polysilicon film by the ion implantation process shown in FIG. However, due to the energy, the polysilicon film is made amorphous and a fine network in silicon is divided, so that a similar semiconductor element can be formed. However, there is no need to dare to form a polysilicon film, which is more difficult to form than an amorphous silicon film, in a film forming step before the silicon film is made amorphous.

Next, as shown in FIG. 1C, a pulse laser 105 having a wavelength of 308 nm is applied to the amorphous silicon film after the implantation from 355 mJ / cm ² to 405 mJ / c.
Irradiation is performed in the energy range of m ² , that is, laser annealing is performed to crystallize the amorphous silicon film 103 to form a polysilicon film 106. The laser irradiation energy at this time depends on the amorphous silicon film 10 to be irradiated.
The thickness is appropriately adjusted depending on the film thickness of No. 3, and is not particularly limited.

Next, as shown in FIG. 1D, after a predetermined resist pattern is formed on the polysilicon film 106 by a photolithography process or the like, the polysilicon film 106 is formed by a CDE (chemical dry etching) process or the like. Pattern it. Then, the SiO ₂ film 102 as an example of the gate insulating film is formed on the patterned polysilicon film 106 by plasma CVD using TEOS-O ₂ or SiH ₄ —O ₂ as a material gas.
Is deposited to a thickness of about 100 nm.

Next, as shown in FIG. 1 (E), SiO ₂
On the film 107, a metal such as Al (aluminum), Ta (tantalum), Cr (chromium), or an alloy thereof is deposited by sputtering to a thickness of about 400 nm. Then, after a predetermined resist pattern is formed on the deposited film by a photolithography process or the like, a gate wiring 108 is formed by an etching process or the like.
Incidentally, such a gate wiring 108 may be formed from a low-resistance polysilicon film.

Next, as shown in FIG. 1 (F), after protecting the entire region including the source and drain regions of the transistors having P-type resist 109 is an impurity serving as a donor ^{31 P, 31} P Impurity ions 110 such as compounds
Using an ion implanter or a non-mass separation type ion implanter, a source region and a drain region to be an N-type transistor are applied with energy of about 80 keV to about 2e1.
Implant 5 / cm ² . Here, a self-aligned thin film transistor is formed in the channel formation region of the polysilicon film 106 by using the gate wiring 108 as a mask. At this time, if the implantation is performed while the substrate 101 is heated to about 150 ° C. or higher, impurities (that is, ³¹ P or the like) can be activated by low-temperature furnace annealing at about 300 ° C. After that, the resist 109 is stripped.

Next, as shown in FIG. 1 (G), after protecting the N-type transistor with a resist 111, the impurity ions 112 such as ^{11 B, 11} B compound which is an impurity serving as an acceptor, the ion implantation apparatus or Using a non-mass separation type ion implantation apparatus, about 2e15 / cm ^{2 is} implanted at an energy of about 30 keV into a source region and a drain region to be a P-type transistor. Here, the gate wiring 1 is formed in the channel formation region of the polysilicon film 106.
08 is used as a mask to form a self-aligned thin film transistor. After that, the resist 111 is peeled off.

Next, as shown in FIG. 1H, an SiO ₂ film 113 serving as an interlayer insulating film is formed by plasma CVD using TEOS-O ₂ or SiH ₄ —O ₂ as a material gas to a thickness of about 500 nm. It is deposited to a thickness. Then, the entire substrate is annealed at about 300 ° C. or higher for one hour to electrically activate the impurities (ie, ¹¹ B and the like).

Finally, as shown in FIG.
After opening a contact hole in the iO ₂ film 113, A
A wiring for electrical connection with a source region and a drain region of a transistor is formed using a conductive material 114 such as l, an Al compound, or ITO.

As described above, in the manufacturing method according to the present embodiment, the A in the ion implantation step shown in FIG.
By implanting r ions, the amorphous silicon film 103
Is a fragmentation of a fine network in silicon. Then, by the laser annealing treatment shown in FIG.
Heat is applied to the amorphous silicon film into which is implanted, and the silicon film is crystallized to form a polysilicon film. Even if the laser irradiation energy in this laser annealing process is not controlled with high precision, the amorphous Using the silicon film, a semiconductor device having constant and good device characteristics can be obtained.

According to the study by the inventors of the present invention, as compared with the case where the heat treatment is performed in the above-described conventional manufacturing method, the threshold characteristics and the current-voltage characteristics of the semiconductor device formed in the device forming process as described above are compared. And the like are insensitive to the degree of heating of the silicon film in the heat treatment step. This phenomenon is caused by the fact that (i) a fine network in silicon in the polysilicon film is divided and homogenized by the implantation of the aforementioned elements in the implantation step, and (ii) the interface between the substrate and the silicon film is (Iii) the heat capacity of the silicon film changes and the crystallization by the heat treatment progresses uniformly, and the heat treatment is performed. It is considered that the crystallization of the polysilicon film is not significantly affected by the degree of heating during the process. However, in any case, the device characteristics of the semiconductor device formed in the device forming process according to the present invention depend on the heat treatment. It reacts insensitively to the heating degree of the silicon film in the process.

Here, the effects of the method of manufacturing the semiconductor device according to the first embodiment described above will be described with reference to FIGS. FIG. 4 shows the relationship between the amount of implanted Ar and the threshold voltage (threshold voltage (V)) in the N-type transistor in three laser irradiation energies (355 mJ / cm ² corresponding to the マ ー ク mark on the graph and ■ mark on the graph). 380 mJ / cm ² , 4 corresponding to the ◆ mark
5 mJ / cm ² ), and FIG.
FIG. 6 is a graph similarly showing the relationship between the amount of injected Ar and the variance of the threshold voltage (square value of the standard deviation) in the N-type transistor for three laser irradiation energies.
7 is a graph similarly showing the relationship between the Ar implantation amount and the threshold voltage in a P-type transistor with respect to three laser irradiation energies. FIG. 7 shows the relationship between the Ar implantation amount and the variance of the threshold voltage in a P-type transistor. Relationship 3 as well
7 is a graph showing two laser irradiation energies. FIG. 8 is a characteristic diagram showing the relationship between the laser irradiation energy and the carrier mobility (crystallinity) of the polysilicon film.

As shown in FIG. 4, in the case of an N-type transistor, the threshold voltage is slightly increased and the laser is not increased when the amount of Ar implanted is up to about 5e13 / cm ² , as compared with the case where no Ar is implanted. If the irradiation energies are different, each threshold voltage also has a relatively large difference of about several volts.
When the amount of implanted Ar is in the range of about 5e13 / cm ² or more, the threshold voltage slightly decreases to a good threshold voltage, and even if the laser irradiation energy is different, the difference between the threshold voltages is small. Is getting smaller.

Further, in this case, as shown in FIG. 5, regarding the dispersion of the threshold voltage, the Ar implantation amount is 5e13 / cm.
^In the range of about ² or more, there is a tendency to converge to a relatively small value of about 0.2 V.

[0054] As shown in FIG. 6, with the case of the P-type transistor, Ar injection amount is in the range of up to about 5e13 / cm ^2, as compared with the case of not injecting, the threshold voltage rises slightly, the laser If the irradiation energies are different, each threshold voltage also has a relatively large difference of about several volts.
When the amount of implanted Ar is in the range of about 5e13 / cm ² or more, the threshold voltage slightly decreases to a good threshold voltage, and even if the laser irradiation energy is different, the difference between the threshold voltages is small. Is getting smaller.

Further, in this case, as shown in FIG. 7, regarding the dispersion of the threshold voltage, the Ar implantation amount is 5e13 / cm.
^In the range of about ² or more, there is a tendency to converge to a relatively small value of about 0.2 V ² .

As shown in FIG. 8, when a thin film transistor is formed according to the present embodiment, the carrier mobility in a channel formation region (polysilicon film) necessary for functioning the thin film transistor is relatively wide. A range of laser irradiation energies (eg, FIGS.
355 mJ / cm ² to 405 mJ
/ Cm ^{2 in} the range of laser irradiation energy). On the other hand, in the case of the comparative example in which the thin film transistor is formed by laser annealing without performing Ar implantation in the present embodiment, the carrier mobility required to make the thin film transistor function has a relatively narrow range of laser irradiation. It can be obtained only by energy (for example, in the case shown in FIGS. 4 to 7, laser irradiation energy in the range of about 375 mJ / cm ² to 385 mJ / cm ² ).

Although not shown in FIGS. 4 to 8, transistor characteristics such as on-current and off-current are also shown in FIG.
It is observed that the off-state current is improved with the threshold voltage, and the off-state current and the variation in the transistor characteristics of the off-state current are also improved.

As described above with reference to FIGS. 4 to 8, according to the present embodiment, crystallization during laser annealing is uniformly performed by implanting Ar of about 5e13 / cm ² or more. In addition to improving the threshold characteristics of each thin film transistor, the dependence of the threshold characteristics on the laser irradiation energy in the laser annealing performed after the implantation of Ar is reduced, and the variation in the threshold characteristics is reduced. Because For example, when laser annealing is performed with the laser irradiation energy set to 380 mJ / cm ² after Ar implantation, this energy is reduced to 3 due to variations in the characteristics of the irradiation apparatus and changes in the operating environment such as the operating temperature.
Even if it deviates to about 80 ± 10 mJ / cm ² , the threshold voltage of the thin film transistor formed through the laser annealing is kept almost constant and good (that is, relatively low), and the threshold voltage is kept high. The variation of the value voltage is also reduced.

As a result, according to the first embodiment,
Even if the laser irradiation energy at the time of the laser annealing is not controlled with high accuracy, a thin film transistor having constant and favorable transistor characteristics can be obtained. That is, a semiconductor device including a thin film transistor having constant and favorable transistor characteristics can be easily manufactured by using a standard laser irradiation apparatus which is currently widely used. Therefore, according to the manufacturing method of the present invention, semiconductor devices with stable (constant) quality can be mass-produced, malfunctions of the semiconductor devices are reduced, and the yield rate is improved. Further, even when a semiconductor device is manufactured by forming a large number of thin film transistors on a large substrate, the transistor characteristics of these thin film transistors can be kept constant and favorable. This is very advantageous because density unevenness does not occur between a plurality of pixels due to variations in transistor characteristics among a plurality of thin film transistors.

According to the manufacturing method of the first embodiment described above, the amorphous silicon film is crystallized (polysilicon) by laser annealing in the heat treatment step. 2 at ℃
Solid phase growth by low temperature annealing for about 0 hours, temperature about 70
The solid phase growth treatment by high-temperature annealing at 0 ° C. for about 1 minute or the lamp annealing treatment may be performed alone or in combination. Even if various heat treatments are performed in this manner, ion implantation of Ar or the like is performed in advance without controlling the degree of heating in each heat treatment step with high accuracy, similarly to the case of laser irradiation energy in laser annealing. Therefore, the polysilicon film crystallized by each heat treatment has less crystallization variation, and also has less variation in transistor characteristics in a finally formed thin film transistor.

According to the manufacturing method of the first embodiment described above, the SiO ₂ film 102 is formed as the base film on the glass substrate 101 in the film forming step shown in FIG. The contamination of the silicon film (103 or 106) from the glass substrate 101 is prevented, and the relatively inexpensive glass substrate 101 secures the physical strength of the entire substrate. However,
If the purity of the glass substrate 101 is sufficiently high, or if a quartz substrate or a silicon substrate is used instead of a glass substrate, the substrate itself can have a function as a base film. In that case, SiO ₂ The membrane 102 can be omitted.

In the first embodiment described above, a positive staggered thin film transistor having a top gate structure is formed on a substrate. Alternatively, a coplanar transistor having a top gate structure may be formed. An inverted staggered thin film transistor having a bottom gate structure may be formed. In the case of a top gate structure, the implantation step and the heat treatment step can be performed relatively easily before forming the gate insulating film and the gate electrode, and the transistor can be formed without controlling the degree of heating in the heat treatment step with high precision. A positive staggered or coplanar thin film transistor having stable (constant) characteristics can be obtained. On the other hand, in the case of a bottom gate structure, after a gate electrode and a gate insulating film are formed, an implantation step and a heat treatment step are performed on the silicon film formed over the substrate through these gate insulating films and the like. An inverted staggered thin film transistor having stable (constant) transistor characteristics can be obtained without controlling the degree of heating in the process with high accuracy.

(Second Embodiment) A method for manufacturing a semiconductor device according to a second embodiment of the present invention will be described with reference to FIG. Here, FIGS. 9A to 9C respectively show:
FIG. 10 is a cross-sectional view illustrating a method for adding a catalyst in the method for manufacturing a semiconductor device according to the second embodiment. 9A to 9C, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In the method of manufacturing a semiconductor device according to the second embodiment, in the heat treatment step for forming a polysilicon film, solid-phase growth is performed by low-temperature annealing instead of the laser annealing shown in FIG. The difference from the first embodiment is that the processing is performed and that a catalyst for promoting crystallization of the amorphous silicon film is added to the amorphous silicon film in the solid phase growth processing. Steps after the heat treatment (see FIGS. 1D to 1J) are the same as in the case of the first embodiment, and a description thereof will be omitted.

In the method of manufacturing a semiconductor device according to the second embodiment, in particular, in the step of forming an amorphous silicon film before or after Ar implantation, the crystallization of the amorphous silicon film in the solid phase growth process is promoted. For example, an amorphous silicon film to which a catalyst such as a metal catalyst such as Ni (nickel) is added is formed on the insulating film.

FIG. 9 (A) shows the method of adding the catalyst.
As shown in FIG.
forming a catalyst film 120a containing i and the like, FIG. 9B
As shown in FIG. 9, a method in which a catalyst film 120b containing Ni or the like is formed under an amorphous silicon film 103b,
As shown in (C), the amorphous silicon film 103c
For example, a method of dispersing and mixing a catalyst 120c containing Ni or the like may be considered.

The catalysts 120a to 120c
Amorphous silicon films 103a to 103 to which
For c, for example, solid phase growth is performed by low-temperature annealing at a temperature of about 600 ° C. for about several hours.

Here, since the crystallinity of the amorphous silicon films 103a to 103c is improved by the catalysts 120a to 120c, the solid-phase growth process by low-temperature annealing is performed at a lower temperature and lower temperature than when no catalyst is used. The polysilicon film can be formed in a short time or at a lower temperature or a shorter time. Therefore, using this polysilicon film, FIG.
By performing the same steps from FIG. 1D to FIG. 1J, a high-quality semiconductor device can be efficiently manufactured as a whole. Incidentally, such a catalyst addition technique can be combined with a solid phase growth treatment by high-temperature annealing, a lamp annealing treatment, and a laser annealing treatment.

The semiconductor device manufactured according to each of the embodiments described above includes a thin film transistor having constant and good transistor characteristics, and is relatively inexpensive and has a high yield. It is also possible to improve image quality particularly in an active matrix drive type display panel or the like in which a large number of semiconductor elements are formed on a large substrate.

[0070]

According to the method of manufacturing a semiconductor device of the present invention, the energy of laser irradiation at the time of laser annealing can be reduced.
Even if the degree of heating in the heat treatment step is not controlled with high precision, a semiconductor element having constant and good element characteristics can be obtained. A semiconductor device including a semiconductor element having element characteristics can be easily manufactured. Therefore, according to the manufacturing method of the present invention, semiconductor devices with stable (constant) quality can be mass-produced, malfunctions of the semiconductor devices are reduced, and the yield rate is improved. Further, even when a semiconductor device is manufactured by forming a large number of semiconductor elements on a large substrate, the element characteristics of these semiconductor elements can be kept constant and good. In this case, it is very advantageous since unevenness in density among a plurality of pixels does not occur due to variation in element characteristics among a plurality of semiconductor elements.

According to the semiconductor device of the present invention, a semiconductor device such as a thin film transistor having a constant high quality is provided, and a semiconductor device which is relatively inexpensive and has a high yield can be realized. It is also possible to improve image quality particularly in an active matrix drive type display panel or the like in which a large number of semiconductor elements are formed on a large substrate.

[Brief description of the drawings]

FIG. 1 is a process chart sequentially showing each process in a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a table showing projected range distances and standard deviations for various energies when ions are implanted into a polysilicon film in the first embodiment.

FIG. 3 is a characteristic diagram schematically showing a projected range and its standard deviation in an amorphous silicon film formed on a SiO ₂ film in the first embodiment.

FIG. 4 is a graph showing a relationship between an Ar implantation amount and a threshold voltage in an N-type transistor formed in the first embodiment.

FIG. 5 is a graph showing the relationship between the amount of implanted Ar and the variance of the threshold voltage in the N-type transistor formed in the first embodiment.

FIG. 6 is a graph showing a relationship between an Ar implantation amount and a threshold voltage in a P-type transistor formed in the first embodiment.

FIG. 7 is a graph showing the relationship between the amount of implanted Ar and the variance of the threshold voltage in the P-type transistor formed in the first embodiment.

FIG. 8 is a characteristic diagram showing a relationship between laser irradiation energy and carrier mobility (crystallinity) of a polysilicon film in the first embodiment and a comparative example.

FIG. 9 is a cross-sectional view illustrating a method of adding a catalyst in a method of manufacturing a semiconductor device according to a second embodiment.

[Explanation of symbols]

101 ... glass substrate 102 ... SiO ₂ film (base film) 103,103a, 103b, 103c ... amorphous silicon film 104 ... Ar 105 ... ion implanter 106 ... polysilicon film 107 ... gate insulating film 108 ... gate wiring 109 ... resist 110 ... impurity ions 111 ... resist 112 ... impurity ions 113 ... SiO ₂ film (interlayer insulating film) 114 ... conductive material 120a, 120b, 120c ... catalyst

Claims (11)

[Claims] A film forming step of forming a silicon film on a substrate, and an element which does not act as a donor or an acceptor in the silicon film and is capable of amorphizing the silicon film. An implantation step of implanting a predetermined amount into the silicon film; a heat treatment step of crystallizing the silicon film into which the element is implanted by applying heat to form a polysilicon film; and an element forming a semiconductor element using the polysilicon film. Forming a semiconductor device. 2. The method according to claim 1, wherein the element includes at least one of an inert gas element, silicon, and a halogen element. 3. The semiconductor device according to claim 1, wherein at least one of a laser annealing process, a solid-phase growth process using low-temperature or high-temperature annealing, and a lamp annealing process is performed in the heat treatment process. Manufacturing method. 4. In the film forming step, an amorphous silicon film as the silicon film is formed on the substrate, and in the implantation step, Ar (argon) as the element is set to 5e13 / cm as the predetermined amount. ^The method according to claim 1, wherein ^two or more implantations are performed, and a laser annealing process is performed in the heat treatment process. 5. A film forming step of forming an amorphous silicon film on a substrate, and forming an amorphous silicon film
A step of injecting (argon) 5e13 / cm ² or more; a heat treatment step of crystallizing the amorphous silicon film into which Ar (argon) is implanted by applying heat to form a polysilicon film; And a device forming step of forming a semiconductor device using the method. 6. In the film forming step, an amorphous silicon film as the silicon film is formed on the substrate, and a catalyst for promoting crystallization of the amorphous silicon film in the heat treatment step is added to the amorphous silicon film. 6. The method of manufacturing a semiconductor device according to claim 1, wherein in the heat treatment step, a solid phase growth process is performed by low-temperature annealing. 7. In the film forming step, the substrate includes a glass substrate and an insulating film formed as a base film on the glass substrate, and the silicon film is formed on the insulating film. A method for manufacturing a semiconductor device according to claim 1. 8. The method of manufacturing a semiconductor device according to claim 1, wherein in the element forming step, at least a thin film transistor is formed as the semiconductor element. 9. The method according to claim 8, wherein the thin film transistor is of a top-gate structure, a staggered type or a coplanar type. 10. The method according to claim 8, wherein the thin film transistor is an inverted staggered type having a bottom gate structure. 11. A semiconductor device manufactured by the method for manufacturing a semiconductor device according to claim 1. Description: