JPH10173201A - Manufacture of insulated-gate type semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an insulated-gate type field-effect transistor having superior characteristics. SOLUTION: A semiconductor layer 13 of an oxygen concentration of 7×10<9> cm<-3> or lower is formed on a glass substrate 11 and the layer 13 is crystallized by heating the layer 13. After that, a plasma hydrogen cleaning is performed on the layer 13 and a gate insulating film 15 is formed on the layer 13. The oxygen concentration of the layer 13 of an insulated-gate type field- effect transistor formed in such a way can be lessened to a concentration of 8×10<18> cm<-3> and the layer 13 shows a high mobility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device using a semiconductor layer manufactured by a manufacturing method having high mass productivity.

[0002]

2. Description of the Related Art Hitherto, a polycrystalline semiconductor device has been manufactured by forming a polycrystalline semiconductor film by low-pressure CVD in a temperature range of 550 ° C. to 900 ° C. and using this polycrystalline semiconductor film.

Recently, large-area liquid crystal displays and the like have been developed, and it has become necessary to form a polycrystalline semiconductor device on a large-area substrate.

[0004] Forming a polycrystalline semiconductor layer directly on a large-area substrate by a low-pressure CVD method has many difficulties due to a problem of a reaction temperature. Usually, a crystallization treatment is performed after forming a non-single-crystal semiconductor film. Thus, a polycrystalline semiconductor layer is formed on a large-area substrate.

When a non-single-crystal semiconductor film is obtained by a low-pressure CVD method, there is a problem that it is difficult to form a film uniformly on a large-area substrate.

Further, when a non-single-crystal semiconductor film is obtained by a plasma CVD method, it takes a long time to form the film, and there is a problem that it is difficult to obtain a uniform film thickness on a large-area substrate.

As a means for solving such a problem, there is a method using a sputtering method. Particularly in the magnetron type sputtering method, a) electrons are confined near the target by a magnetic field, and damage to the substrate surface by high energy electrons is suppressed. B) High-speed film formation over a large area at low temperatures. C) Since no dangerous gas is used, safety and industrial efficiency are high. There are advantages such as.

[0008] However, it is known that the semiconductor film obtained by the sputtering method has a microstructure, that is, the presence of silicon atoms is biased, so that thermal crystallization is difficult.

[0009]

SUMMARY OF THE INVENTION The present invention solves such a problem and provides a method for more effectively manufacturing a semiconductor device using a semiconductor film which can be thermally crystallized at a lower temperature. is there.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a method for forming a semiconductor film by sputtering on a substrate in an atmosphere of hydrogen or an inert gas containing hydrogen, and a method for forming a semiconductor film obtained by the sputtering. A silicon oxide film is formed by a sputtering method in an atmosphere of oxygen or an inert gas containing oxygen before or after, and each of the films is formed in a dedicated reaction chamber. It is characterized in that it can be formed continuously in the same device without specifying it.

By forming each of these films in a dedicated reaction chamber, the amount of oxygen in the semiconductor film is reduced to 7 × 10 ¹⁹ cm ⁻³ or less, most preferably 1 × 10 ¹⁹ cm ⁻³ or less. It is to be.

As an example of a technique for forming a part of the semiconductor film as a channel formation region, an amorphous material obtained by sputtering in an atmosphere of hydrogen or an inert gas containing hydrogen (amorphous or extremely amorphous) is obtained. Near) semiconductor film (hereinafter referred to as Si film) at 450 ° C to 700 ° C, typically 60 ° C
By applying a temperature of 0 ° C. to the semiconductor film to crystallize at least the channel formation region, an active layer for an insulating gate type semiconductor device of the present invention can be obtained.

Conventionally, there has been known an example in which a thin film transistor is manufactured using an a-Si (amorphous silicon) film obtained by a sputtering method to which hydrogen is added, but its electric characteristics are known to be low. . Therefore, an a-Si film is generally obtained by a sputtering method without adding hydrogen.

However, the present inventor can prevent the formation of a microstructure in the formed a-Si film by adding hydrogen in the sputtering method. It has been found that 700 ° C. can be thermally crystallized at a low temperature below 600 ° C.

The semiconductor film after the crystallization has an average crystal grain size of about 5 to 400 ° and a hydrogen content in the semiconductor film of 5 atomic% or less. In addition, the semiconductor film having this crystallinity has lattice distortion, and the interfaces of the crystal grains are in close contact with each other microscopically, and have an effect of eliminating a barrier for carriers at the crystal grain boundaries.

For this reason, at a polycrystalline grain boundary having no lattice distortion, impurity atoms such as oxygen segregate to form a barrier (barrier) and hinder the movement of carriers. When formed in a dedicated sputtering reaction chamber, the amount of oxygen present in the film is 7 × 10 ¹⁹ cm ^−3, preferably 1 × 10 ¹⁹
can be reduced to a very small amount of cm ^-3 or less,
Further, since the formed semiconductor film has lattice distortion, a barrier is not formed or its existence is negligible, so that its electron mobility is also very good as 50 to 300 cm ² / Vsec. Had.

Further, the semiconductor film obtained by the plasma CVD method has a large proportion of an amorphous component, and the amorphous component is naturally oxidized to form an oxide film up to the inside. On the other hand, the sputtered film is dense and naturally oxidized. Does not proceed to the inside of the semiconductor film, and is oxidized only in the vicinity of the surface. Due to this denseness, crystal grains having lattice distortion strongly push each other, and an energy barrier against carriers near the crystal grain interface. Is not formed.

The present invention provides a method for manufacturing an insulated gate semiconductor device by positively utilizing the excellent characteristics of a semiconductor film formed by such a sputtering method.
For this purpose, individual films are produced in a dedicated sputtering reaction chamber.

The silicon oxide film formed by this sputtering method can be used as an insulating film or a gate insulating film on a substrate, and the semiconductor film can be used as an active layer or an impurity layer and further as a gate electrode.

As described above, according to the method of the present invention, all the parts necessary for the insulating gate type semiconductor device can be manufactured by the sputtering method. For this reason, in the insulating gate type semiconductor device as shown in FIG. 1D, the lower part (18) of the active layer, that is, the contact portion with the underlying insulating film is partially oxidized and becomes a state of SiOx. The electrical characteristics are slightly worse. As a result, a back channel cannot be generated in this portion, and the reverse leakage current can be reduced. This is very effective when this semiconductor device is used as a CMOS, and shows a significant effect in reducing off-state current.

Further, since the semiconductor film is formed by a sputtering method, its particle size is 5 to 40 after thermal crystallization.
Since the grain size is so small, the reverse leakage at this portion can be reduced by the N ⁺ -I (P ⁺ -I) junction. Hereinafter, the present invention will be described in detail with reference to Examples.

[0022]

【Example】

Embodiment 1 In this embodiment, a silicon semiconductor layer having crystallinity is obtained by thermally crystallizing a Si film produced by a multi-chamber magnetron type RF sputtering apparatus as schematically shown in FIG. This is an example in which a thin film transistor is manufactured using a silicon semiconductor layer.

As shown in FIG. 2, this multi-chamber type sputtering apparatus comprises a pre-chamber (1), a substrate passage chamber (2), a silicon oxide reaction chamber (3), and a semiconductor film reaction chamber (4). (6) (7)
(8), each of which is connected to the system, and each chamber is completely independent and can exhaust and introduce gas.

The exhaust system includes a reaction and low vacuum exhaust system in which a rotary pump and a turbo molecular pump are connected in series, and a high vacuum exhaust system in which a cryopump is further connected.
It is equipped with a system and can exhaust up to 1 × 10 ^-7 Pa as back pressure.

When a substrate is loaded into each chamber, the gate valve that separates the chambers is opened and closed. In this opening and closing, the pressure difference between the two chambers is reduced and the two chambers are opened and closed. Performed after the atmosphere gas is prepared. This can minimize mixing of unnecessary impurities and the like.

The strength of the magnetic field supply means provided near the sputtering target can be varied by external control (for example, by varying the amount of applied power or the distance from the target).

A heating means and an atmosphere gas supply means are provided in the substrate passage chamber (2) of the sputtering apparatus so that the semiconductor film can be heat-treated, so that the thermal crystallization of the semiconductor film can be performed without taking the substrate out of the apparatus. Is possible. Further, before forming a film on the substrate, the substrate is subjected to a heat treatment in the substrate passage chamber, and once the substrate is thermally contracted, a film can be formed on the substrate. The stress remaining in the film is reduced, and the adhesion between the base and the film is further improved.

FIG. 1 shows a thin film transistor manufacturing process manufactured in this embodiment.

First, 10 glass substrates (11) / cassette are set in the preliminary chamber (1) through the gate valve (5), and one of them is passed through the substrate passage chamber (2) to form a silicon oxide film. It was loaded into the reaction chamber (3). A SiO ₂ film (12) was formed on a glass substrate (11) by magnetron RF sputtering under the following conditions.
It was formed to a thickness of 0 nm. O ₂ 100% atmosphere Deposition temperature 150 ℃ RF 813.56NHz) Output 400W Pressure 0.5Pa Single crystal silicon is used as target

After the formation, the reaction chamber is evacuated to a high vacuum, the gate valve is opened and closed, the substrate is taken out to the passage chamber, and the substrate is similarly transferred to the semiconductor film reaction chamber (4). An Si film (13) is formed to a thickness of 100 nm.

At this time, the back pressure was set to 1 × 10 ⁻⁷ Pa or less, and exhaust was performed using a turbo molecular pump and a cryopump. The amount of the supplied gas had a purity of 5N (99.999%) or more, and the additional gas used was 4N or more of argon used as needed. The target single crystal silicon is also 5 × 10 ¹⁸ cm
The oxygen concentration was ^-3 or less, for example, 1 × 10 ¹⁸ cm ^-3 , and oxygen as an impurity in the formed film was extremely reduced.

The film forming conditions are as follows: H ₂ / (H ₂ + Ar) = 80% (partial pressure ratio) under an atmosphere of argon and hydrogen, which are inert gases, film forming temperature 150 ° C. RF (13.56 MHz) output 400 W total pressure The pressure was set to 0.5 Pa, and a single crystal Si target was used as the target.

Thereafter, the substrate (11) is returned to the substrate passage chamber again, where it is heated in a temperature range of 450 ° C. to 700 ° C., particularly at a temperature of 600 ° C. for 10 hours in hydrogen or an inert gas. Performed thermal crystallization of the Si film (13) in a 100% nitrogen atmosphere to produce a highly crystalline silicon semiconductor layer (semi-amorphous or semi-crystalline).

The impurity purity in the amorphous silicon film formed by the above method and the film crystallized by the heat treatment was examined by SIMS (Secondary Ion Equivalent Analysis). Then, among the impurity concentrations during the film formation, oxygen was 8 × 10 ¹⁸ cm ⁻³ and carbon was 3 × 10 ¹⁶ cm ⁻³ . Hydrogen had a concentration of 4 × 10 ²⁰ cm ⁻³ , which was equivalent to 1 atomic% when the density of silicon was 4 × 10 ²² cm ⁻³ . These were examined on the basis of the oxygen concentration of the target single crystal silicon of 1 × 10 ¹⁸ cm ⁻³ . In this SIMS analysis, the distribution in the depth direction (depth profile) of the film after film formation was examined, and the minimum value was used as a reference. This is because the surface has silicon oxide which is naturally oxidized with the atmosphere.
These values did not change significantly even after the crystallization treatment, and the oxygen impurity concentration was 8 × 10 ¹⁸ cm ⁻³ .

In this example, oxygen was increased to make sure, for example, N ₂ O was added at 0.1 cc / sec and 1 cc / sec. Then, the oxygen concentration after crystallization is 1 × 10 ²⁰ cm ⁻³ , 4 × 10
^It increased to ²⁰ cm ^-3 . However, when such a coating was used, at the same time, crystallization could be performed only by increasing the temperature required for crystallization to 700 ° C. or more, or increasing the crystallization time by at least five times.

That is, considering industrially the softening temperature of the glass of the substrate, the treatment at 700 ° C. or lower, preferably 600 ° C. or lower is important, and it is also important to further reduce the time required for crystallization. However, no matter how much impurities such as oxygen concentration are reduced, a-
Crystallization of Si semiconductors was not possible experimentally.

In the present invention, as a result of using such a high-quality sputtering apparatus, the oxygen concentration during film formation was 1 × 10 ²⁰ cm ⁻³ or more due to leakage from the apparatus. In such a case, such characteristics of the present invention cannot be expected.

[0038] It is the oxygen concentration of 7 × 10 ¹⁹ cm ^-3 or less in the as of nuclear, and the heat treatment temperature was determined to be 450 to 700 ° C..

As can be seen from the data of the laser Raman analysis shown in FIG. 6, the peak position indicating the presence of crystals in this semiconductor film is shifted to a lower wavenumber side as compared with the peak position of normal single crystal silicon. And the existence of lattice distortion was inevitable.

In the present embodiment, the present invention is described using a silicon semiconductor. However, a germanium semiconductor or a semiconductor in which silicon and germanium are mixed can be used. It was possible to reduce the temperature added during crystallization by about 100 ° C.

Next, the substrate was taken out of the apparatus, and the thermally crystallized silicon semiconductor film was subjected to device isolation patterning to obtain the shape shown in FIG. 1 (A). The device was configured as a channel forming region.

Next, the substrate is returned to the sputtering apparatus again, and a gate oxide film (SiO ₂ ) is formed in a reaction chamber (3) dedicated to silicon oxide.
(15) was formed to a thickness of 100 nm by magnetron RF sputtering under the following conditions. Before forming the gate insulating film, a bias is applied to the substrate side in a 100% hydrogen atmosphere, and the semiconductor (13)
Was subjected to plasma hydrogen cleaning.

The conditions for forming the gate insulating film are as follows: oxygen 95% by volume NF ₃ 5% by volume Pressure 0.5pa Film formation temperature 100 ° C RF (13.56MHz) output 400W

When the gate oxide film is formed, the ratio of oxygen to the inert gas is increased and most preferably 100% oxygen is sputtered, whereby the interface state density of the gate insulating film can be reduced and the characteristics are very good. A transistor can be realized.

In this embodiment, since NF ₃ was added as a part of the reaction gas during the reaction, fluorine was added to the gate insulating film. As a result, the dangling bonds of silicon in the film were neutralized, and the cause of the generation of fixed charges in the film could be eliminated.

Next, from a multi-chamber sputtering apparatus,
The substrate is taken out and a semiconductor layer mixed with phosphorus is formed thereon by a low pressure CVD method. Thereafter, photolithography was performed using a predetermined mask pattern, and the semiconductor film containing phosphorus was formed as a gate electrode (20). FIG.
(B)

By forming this electrode by the low pressure CVD method, good characteristics can be obtained without damaging the underlying gate insulating film.

The gate electrode is not limited to the doped semiconductor layer, and other materials can be used.
Next, impurity regions (14) and (14 ') are formed in the self-alignment line by ion implantation using the resist pattern or the like used for etching the gate electrode (20) or the gate electrode (20) as a mask. did. Thereafter, thermal annealing was performed at 400 ° C. for 15 minutes in a hydrogen atmosphere to activate.

Thus, the semiconductor layer below the gate electrode (20) was formed as a channel region of the insulated gate type semiconductor device.

Next, an interlayer insulating film is formed covering all of these upper surfaces.
(17) was formed, and the state of FIG. 1 (C) was obtained. Thereafter, holes for contacting the source and drain electrodes are formed, and metallic aluminum is formed on the upper surface by sputtering, and is subjected to a predetermined patterning, so that the source and drain electrodes (16) and (1) are formed.
6 ') to complete the insulated gate semiconductor device.
Fig. 1 (D)

In the case of this embodiment, the semiconductor layer forming the channel region and the source and drain semiconductor layers are made of the same material, so that the process can be simplified. In addition, since the same semiconductor layer is used, the source and drain semiconductor layers also have crystallinity and have high carrier mobility, so that an insulated gate semiconductor device having better electric characteristics can be realized.

The above is a method for manufacturing a thin film transistor using the thermocrystalline silicon semiconductor layer manufactured in this embodiment. For comparison, the channel forming region shown in FIG.
Four examples are shown below, in which the hydrogen concentration and the oxygen concentration, which are the conditions for forming the layer (13) by the magnetron type RF sputtering method, are changed.

[0053] (Reference Example 1) This reference example of the channel forming region in the production process FIG 1 (A) a partial pressure ratio of the atmosphere during sputtering of making the (13) H ₂ / Example 1 ( (H ₂ + Ar) = 0% (partial pressure ratio), and the others were produced in the same manner as in Example 1. At this time, the oxygen concentration was 2 × 10 ²⁰ cm ⁻³ .

[0054] (Reference Example 2) This reference example of the channel forming region in the production process FIG 1 (A) a partial pressure ratio of the atmosphere during sputtering of making the (13) H ₂ / Example 1 ( (H ₂ + Ar) = 20% (partial pressure ratio), and the others were produced in the same manner as in Example 1. At this time, the oxygen concentration was 7 × 10 ¹⁹ cm ⁻³ .

[0055] (Reference Example 3) This example of a channel forming region in the production process FIG 1 (A) a partial pressure ratio of the atmosphere during sputtering of making the (13) H ₂ / Example 1 ( (H ₂ + Ar) = 50% (partial pressure ratio), and the others were produced in the same manner as in Example 1. At this time, the oxygen concentration was 3 × 10 ¹⁹ cm ⁻³ .

[0056] (Reference Example 4) This Example is of a channel-forming region in the production process FIG 1 (A) a partial pressure ratio of the atmosphere during sputtering of making the (13) H ₂ / Example 1 ( (H ₂ + Ar) = 70% (partial pressure ratio), and the others were produced in the same manner as in Example 1. At this time, the oxygen concentration was 1 × 10 ¹⁹ cm ⁻³ .

The results of comparing the electrical characteristics of the above described examples are shown below. FIG. 4 shows the completed Example 1 and Reference Examples 1 to 1.
Carrier mobility μ (FIELD M
OBILITY) and the hydrogen partial pressure ratio during sputtering (P _H / P _{TO TA}
= H ₂ / (H ₂ + Ar)) in a graph.

The correspondence between the plot points in FIG. 4 and each of the above examples is shown in Table 1 below.

[0059]

[Table 1]

[0060] When the hydrogen partial pressure according to Figure 4 is 0% since the oxygen concentration is also ^{2 × 10 20 cm -3, 3} × 10 -1 cm 2 V / sec and very small, and the other, the present invention Remarkably high mobility 2cm ² / Vs at 20% or more and oxygen concentration 7 × 10 ¹⁹ cm ^-3 or less
It can be seen that μ (FIELD MOBILITY) is obtained not less than ec.

This is presumably because, when hydrogen was added, oxygen in the chamber in the sputter was converted to water, which was positively removed by a cryopump.

FIG. 5 is a graph showing the relationship between the threshold voltage and the hydrogen partial pressure ratio during sputtering (P _H / P _TOTAL = H ₂ / (H ₂ + Ar)). Hydrogen partial pressure ratio (P _H / P _TOTAL = H ₂ / (H ₂ + Ar))
And the correspondence between the example numbers is the same as in the case of Table 1.

Considering that the lower the threshold voltage, the lower the operating voltage for operating the thin film transistor, ie, the lower the gate voltage, the better the characteristics of the device can be obtained. A normally-off state with a threshold voltage of 8 V or less can be obtained by a sputtering method under a high condition. That is,
Si shown in (13) of FIG.
It can be seen that a device using a semiconductor layer having crystallinity obtained by obtaining a film and thermally crystallizing this Si film shows good electrical characteristics.

FIG. 5 shows that the higher the hydrogen partial pressure ratio, the lower the threshold voltage. From this, it can be seen that when the a-Si film serving as the channel formation region in each of the above examples is manufactured by the sputtering method, increasing the partial pressure ratio of hydrogen tends to increase the electrical characteristics of the device.

The mechanism of the semi-amorphous or semi-crystalline semiconductor used in the present invention will be briefly described.

That is, when a single-crystal silicon semiconductor is used as a target in the sputtering method and sputtering is performed with a mixed gas of hydrogen and argon, atomic silicon is separated from the target by sputtering (impact) of heavy atoms of argon, and the target is formed. While flying on a substrate having a surface, a cluster of tens to hundreds of thousands of atoms solidified at the same time leaves the target as a cluster and flies to the surface to be formed.

During this flight, hydrogen combines with the dangling bonds of silicon outside and around the cluster to form a region having a relatively high order on the surface on which the cluster is formed.

That is, a mixture of pure amorphous silicon and clusters having high order and having Si—H bonds in the periphery is formed on the surface on which the film is formed. This is heat-treated in a non-oxidizing gas at 450 to 700 ° C to
The Si-H bond reacts with another Si-H bond to form a Si-Si bond.

However, at the same time that the bonds are attracting each other, the highly ordered clusters tend to shift to a more highly ordered state, ie crystallization. However, between adjacent clusters, Si-Si bonded to each other pulls between the clusters. As a result, the crystal has lattice strain and the crystal peak in laser Raman is 520 cm ⁻¹ of a single crystal.
It is measured shifted to a lower wave number side.

Further, since the Si-Si bond between the clusters anchors (connects) each other, the energy band in each cluster may be electrically connected to each other via the anchoring portion. Therefore, it is fundamentally different from polycrystalline silicon in which a crystal grain boundary acts as a carrier barrier, and a carrier mobility of 10 to ²⁰⁰ cm ² / V Sec can be obtained.

That is, as in the present invention, a semi-amorphous or semi-crystal based on such a definition can be expected to have a state in which although it has apparent crystallinity, there is substantially no crystal grain boundary electrically.

Of course, instead of the intermediate temperature annealing of 450 ° C. to 700 ° C. in the case of a silicon semiconductor,
When crystallizing with a crystal growth of 00 ° C. or higher, oxygen and the like in the film are bent out to the grain boundary due to the crystal growth to form a barrier. This is a material having the same crystal and grain boundaries as a single crystal.

When the degree of anchoring between clusters in the semiconductor is increased, the carrier mobility is further increased. For this purpose, the amount of oxygen in this film is reduced by 7 ×
10 ¹⁹ cm ^-3, preferably 1 × 10 ¹⁹ cm ^-3 or less,
In addition to being able to crystallize at a temperature lower than 600 ° C., high carrier mobility can be obtained.

FIG. 6 shows Reference Examples 1, 2, 3, and 4 of the present invention.
When the partial pressure ratio of hydrogen was set to 0%, 20%, and 50% at the time of sputtering when producing the Si film (13) to be a channel formation region of the a-Si film, the a-Si film was thermally crystallized. 3 shows a Raman spectrum of a silicon semiconductor layer having the following.

Table 2 shows the relationship between the symbols shown in FIG. 6, the example numbers, and the hydrogen partial pressure ratio during sputtering.

[0076]

[Table 2]

Referring to FIG. 6, the curve (6) is compared with the curve (61).
2) That is, comparing the case where the hydrogen partial pressure ratio is 0% and the case where the hydrogen partial pressure ratio is 20% at the time of forming the Si semiconductor layer to be a channel formation region, It can be seen that the Raman spectrum when the pressure ratio is 20% remarkably shows the crystallinity of the semiconductor silicon.

The average crystal grain size is 5 to 5 times the half width.
400Å typically 50-300Å. The peak position of the Raman spectrum was shifted to a lower wavenumber side than the peak position of single crystal silicon, 520 cm ⁻¹ , and clearly had lattice distortion.

This clearly shows the features of the present invention. That is, the effect of the production of the Si film by the sputtering method to which hydrogen is added appears only when the Si film is thermally crystallized.

As described above, when there is lattice distortion, each of the fine crystal grains is in a state of being forcibly shrunk to each other. There is no energy barrier for carriers in
In addition, segregation of impurities such as oxygen hardly occurs, and as a result, high carrier mobility can be realized.

The grain size in the present invention is a numerical value calculated by a Raman spectrum obtained when a manufactured semiconductor film is subjected to Raman spectroscopic analysis, and it is determined whether or not a grain boundary actually exists in the film. It is unknown, but rather, it is considered that there is no grain boundary as described above.

As a method of changing the crystal grain size of the semiconductor film, a method of changing the applied RF power at the time of sputtering film formation can be considered.

As another method, the intensity of the magnetic field of the magnetic field supply means provided near the target may be changed. For example, when the magnetic field supply unit is an electromagnet, increasing the current flowing through the coil to increase the magnetic field can increase the particle size of the semiconductor film formed on the substrate. The reverse is also possible.

Table 3 below shows data showing the effects of the present invention.

[0085]

[Table 3]

In Table 3, the hydrogen partial pressure ratio refers to the Si film serving as the channel formation region in this embodiment (FIG. 1A).
(13)) is a condition for producing by magnetron type RF sputtering.

The S value is the value of [d (ID) / d (VG)] ⁻¹ at the rising portion of the curve in the graph showing the relationship between the gate voltage (VG) and the drain current (ID) showing the characteristics of the device. The smaller the value, the sharper the slope of the curve showing the (VG-ID) characteristic and the higher the electrical characteristics of the device. VT indicates a threshold voltage. μ indicates the carrier mobility, and the unit is (cm ² / V · s). The on / off characteristic is a logarithmic value of the ratio of the ID value to the minimum ID value at VG = 30 volts in the curve showing the (VG-ID) characteristic.

In this embodiment, the underlying silicon oxide film and the semiconductor film are continuously formed in a dedicated reaction chamber. However, the present invention is not limited to this case. However, it is apparent that continuously forming a semiconductor film and a gate insulating film or a gate insulating film and a gate electrode in a dedicated reaction chamber is also within the scope of the technical idea of the present invention.

[Embodiment 2] In this embodiment, an insulated gate semiconductor device having the structure shown in FIG. 3 will be described.

Although the silicon oxide film is coated on the insulating substrate in the same manner as in the first embodiment, in this embodiment, the formation of the gate insulating film is completed before the formation of the semiconductor layer forming the channel region. The method is shown. On the insulating film (12), metal molybdenum was formed to a thickness of 3000 mm by a sputtering method, and predetermined patterning was performed to form a gate electrode (20).

Next, a gate oxide film (SiO ₂ ) (SiO ₂ ) (SiO ₂ ) (SiO ₂ ) (SiO ₂ ) 15) Magnetron type R to a thickness of 100 nm
Films were formed by the F sputtering method under the following conditions. Oxidizing atmosphere 100% Pressure 0.5pa Film forming temperature 100 ℃ RF (13.56MHz) output 400W A silicon target or a synthetic quartz target was used.

When the oxide film is formed, the interface state density of the gate insulating film can be reduced by sputtering with a large ratio of oxygen to the inert gas, most preferably 100% oxygen, so that the characteristics are very good. A transistor can be realized.

Next, the substrate is moved to a reaction chamber dedicated to the semiconductor film, and a-
A Si film (13) is formed to a thickness of 100 nm.

The film formation conditions were as follows: H ₂ / (H ₂ + Ar) = 80% (partial pressure ratio) in an atmosphere of argon and hydrogen, which are inert gases, film formation temperature 150 ° C. RF (13.56 MHz) output 400 W total pressure The pressure was set to 0.5 Pa, and a Si target was used as a target.

Thereafter, the substrate on which the semiconductor film has been formed is taken out of the reaction chamber, and the substrate is not taken out of the apparatus, but is allowed to stand in the substrate passage chamber at a temperature in the range of 450 ° C. to 700 ° C., particularly at a temperature of 600 ° C. for 10 hours. Then, the a-Si film (13) was thermally crystallized in hydrogen or an inert gas, in this example, in an atmosphere of 100% nitrogen, to produce a silicon semiconductor layer having high crystallinity. At this time, the substrate was newly moved from the preliminary chamber to the reaction chamber dedicated to the silicon oxide film, and a gate insulating film was formed under the above-described conditions.

The amount of oxygen impurities present in the semiconductor film formed by such a method was 1 × by SIMS analysis.
10 ¹⁹ cm ^-3 , carbon was 4 × 10 ¹⁸ cm ^-3 , and the content of hydrogen was 1% or less. As a result, a channel region (22) could be formed on the gate electrode (20). During this heat treatment, the substrate introduced into the silicon oxide reaction chamber later for the production of the gate insulating film is moved through the substrate passage chamber to the semiconductor film reaction chamber, and the semiconductor film is formed under the same conditions. went.

Next, the substrate after the heat treatment is removed from the passage chamber by N.
After moving to the reaction chamber for forming a semiconductor film, the n ⁺ a-Si film (14) was
The film was formed to a thickness of nm. At the same time, the substrate on which the formation of the semiconductor film was completed was subjected to heat treatment in the substrate passage chamber, and at the same time, a new substrate was introduced into the reaction chamber for the gate insulating film.

The film forming conditions are as follows: in an atmosphere having a hydrogen partial pressure ratio of 10 to 99% or more (80% in this embodiment) and an argon partial pressure ratio of 10 to 99% (19% in this embodiment), a film forming temperature of 150 ° C. RF (13.56 MHz) output 400 W Total pressure 0.5 Pa, and single crystal silicon doped with phosphorus was used as a target.

Next, an aluminum film for source and drain electrodes is formed on the semiconductor layer (14) and patterned, and the source and drain impurity regions (14) (1) are formed.
4 ′) and source and drain electrodes (16) and (16 ′) were formed to complete the semiconductor device.

In this embodiment, since the gate insulating film is formed before the formation of the semiconductor film in the channel formation region,
During the thermal crystallization process, the vicinity of the interface between the gate insulating film and the channel region is appropriately thermally annealed, and the interface state density can be reduced.

When forming each film, the back pressure was set to 1 × 1
Since the pressure is 0 ^-6 Pa or less and the exhaust system is a combination of a turbo-molecular pump and a cryopump, the film can be formed in a state where there are few oil-free impurities. The oxygen impurity amount in the active layer (13) in this embodiment is 1 × 10 ¹⁹ cm ⁻³ ,
Its mobility μ was 41.4.

Although an a-Si film is used as a semiconductor layer to be thermally crystallized in this embodiment and the like, it can be said that the present invention is also effective when thermally crystallizing another non-single-crystal semiconductor. Not even.

Although Ar was used as the inert gas at the time of the above-mentioned sputtering, a halogen gas such as He or a gas obtained by converting a reactive gas such as SiH ₄ or Si ₂ H ₆ into plasma was used as another gas. May be. Further, in the formation of the a-Si film by the magnetron type RF sputtering method of this embodiment, the hydrogen concentration is 5 to 100%, the film formation temperature is in the range of 50 to 500 ° C., and the RF output is in the range of 500 Hz to 100 GHz. 1W ~ 10MW
Can be arbitrarily selected in the range described above, or may be combined with a pulse energy source.

By using more intense light irradiation (wavelength of 1000 nm or less) energy or electron cyclotron resonance (ECR) conditions, the plasma may be further increased to make the plasma more hydrogen.

This is because micro atoms in a film formed by sputtering by making light atoms of hydrogen into plasma to efficiently generate positive ions necessary for sputtering, and in the case of this embodiment, an a-Si film This is to prevent the generation of microstructures inside. Further, the other reactive gas may be applied to the above means.

In this embodiment, the amorphous semiconductor film is simply formed by a-Si.
Described as a membrane. This usually indicates a silicon semiconductor, but may be germanium or a mixed Si _x Ge _1-x (0 <X <1) of silicon and germanium.

It is needless to say that the structure of the present invention can be applied to a staggered type, coplanar type, inverted staggered type, and inverted coplanar type insulated gate field effect transistor.

[0108]

According to the constitution of the present invention, a problem arises in the step of obtaining a semiconductor having crystallinity by thermally crystallizing a non-single-crystal semiconductor obtained by an industrially useful sputtering method. It was possible to solve the problem of difficulties in forming a thin film transistor, and to manufacture a high-performance thin film transistor using the semiconductor layer having this crystallinity.

Further, according to the method of the present invention, all the parts required at a minimum for the insulated gate type semiconductor device can be manufactured by the sputtering method. For this reason, in the insulating gate type semiconductor device as shown in FIG.
In other words, a portion in contact with the base insulating film is partially oxidized to have a semi-insulating property, and the electrical characteristics at this portion are slightly deteriorated. As a result, a back channel cannot be generated in this portion, and the reverse leakage current can be reduced. This is very effective when this semiconductor device is used as a CMOS, and shows a significant effect in reducing off-state current.

Further, the concentration of oxygen impurities present in the semiconductor film can be reduced, a barrier to carriers near the crystal grain boundaries is hardly formed, and an insulated gate semiconductor device having extremely high mobility is realized. We were able to.

Further, since a plurality of different processes can be performed in the same apparatus, continuous processes can be performed without being affected by outside. In addition, since a plurality of processes can be performed simultaneously, productivity can be increased.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of Example 1.

FIG. 2 is a schematic diagram of a multi-chamber sputtering apparatus for the present invention.

FIG. 3 is a sectional view of another embodiment of the present invention.

FIG. 4 shows a relationship between a hydrogen partial pressure ratio and carrier mobility.

FIG. 5 shows a relationship between a partial pressure ratio of hydrogen and a threshold.

FIG. 6 shows a Raman spectrum of a semiconductor film having crystallinity of the present invention.

[Explanation of symbols]

 (1) ・ ・ ・ Preparatory chamber (2) ・ ・ ・ Substrate passage chamber (3) (4) ・ ・ Sputter chamber (5) (6) (7) (8) ・ ・ ・ Gate valve

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/316 H01L 29/78 627E

Claims (5)

[Claims] 1. A method for manufacturing an insulated gate semiconductor device on a substrate, comprising a step of performing plasma hydrogen cleaning on a surface of a semiconductor layer to be a channel formation region of the insulated gate semiconductor device. Of manufacturing an insulating gate type semiconductor device. 2. A method for manufacturing an insulating gate type semiconductor device on a substrate, comprising applying a bias to the substrate side, and performing plasma hydrogen cleaning on a surface of a semiconductor layer to be a channel forming region of the insulating gate type semiconductor device. A method for manufacturing an insulated gate semiconductor device, comprising: 3. The method for manufacturing an insulated gate semiconductor device according to claim 1, further comprising a step of forming a film on the semiconductor layer after the step. 4. The method according to claim 3, wherein the coating is a silicon oxide film. 5. The method according to claim 3, wherein the step of performing the plasma hydrogen cleaning and the step of forming the film are performed in the same reaction chamber.