JP2007274005A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a fine semiconductor device with short channel length, while preventing single channel effect. <P>SOLUTION: An impurity region 104 in the form of a dot pattern is formed in a channel forming region 103. A channel width W is substantially subdivided by the dot pattern to alleviate the fall of a threshold voltage associated with short channel effect. On the other hand, since the dot pattern is formed deeply in the interior of the semiconductor, the spread of a drain side depletion layer to the channel region 103 can be prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The invention disclosed in this specification describes an insulated gate semiconductor device formed using a crystalline semiconductor substrate, for example, a single crystal silicon substrate or an SOI substrate (SIMOX, etc.), particularly an insulated gate field effect transistor (hereinafter simply referred to as IG). -Abbreviated as -FET) and a manufacturing method thereof. In particular, this technique is effective when a microelement having a channel length of 1 μm or less (typically 0.01 to 0.35 μm) is manufactured.

  Therefore, the present invention can be applied to various semiconductor integrated circuits such as IC, VLSI, and ULSI configured by integrating IG-FETs.

  In recent years, integrated circuits such as VLSI have been increasingly miniaturized, and the processing width in the deep submicron region such as the width of the wiring is 0.18 μm or less, and further 0.1 μm or less has been required. Yes.

  Until now, the miniaturization of semiconductor elements has been advanced according to the scaling law, and it has been generally known that the miniaturization brings about the improvement of the characteristics of the integrated circuit. However, when microfabrication is performed in the sub-micron region, a problem that simply does not follow the scaling law occurs.

  As such a problem, a phenomenon called a short channel effect is typically known. The short channel effect means that as the line width of the gate electrode becomes shorter, that is, as the channel formation region becomes shorter, the charge of the channel formation region is not limited to the gate voltage but also the depletion layer charge of the source / drain region, the electric field and the potential distribution. It is a phenomenon that is caused to become greatly affected.

  This state is simplified and shown in FIG. Reference numeral 301 denotes a source region, 302 denotes a drain region, 303 denotes a channel region, and 304 denotes a gate electrode. A dotted line indicated by 305 represents a depletion layer formed when the drain voltage Vd is small.

  Usually, the current flowing through the channel region 303 is controlled only by the gate voltage Vg. In this case, as indicated by 305, the depletion layer near the channel region 303 is substantially parallel to the channel, and a uniform electric field is formed.

  However, when the drain voltage Vd increases, the depletion layer in the vicinity of the drain region 302 spreads toward the channel region 303 and the source region 301, and the charge and electric field of the drain depletion layer are reduced as indicated by the solid line indicated by 306. This affects the depletion layer near the source region 301 and the channel region 303. That is, the on-current changes due to a complicated electric field distribution, which makes it difficult to control only with the gate voltage Vg.

  Here, the energy state around the channel formation region when the short channel effect occurs will be described with reference to FIG. 4 is an energy band diagram of the source region 401, the channel formation region 402, and the drain region 403 when the drain voltage is 0V.

  When a sufficiently large drain voltage Vd is applied in this state, the state changes to a state shown by a dotted line in FIG. That is, the depletion layer charge or electric field of the drain region 103 formed by the drain voltage Vd affects the depletion layer charge of the source and channel regions 401 and 402, and the energy (potential) state changes from the source region 401 to the drain region 403. It will change continuously.

  As the influence of such a short channel effect on a semiconductor element, for example, an IG-FET, a decrease in threshold voltage (Vth) and a punch-through phenomenon are well known. It is also known that when the influence of the gate voltage on the drain current is reduced due to the punch-through phenomenon, the subthreshold characteristic is deteriorated.

  First, the decrease in threshold voltage is a phenomenon that can be seen in the same way for both N-channel and P-channel FETs. The degree of this reduction depends not only on the drain voltage but also on various parameters such as substrate impurity concentration, source / drain diffusion layer depth, gate oxide thickness, and substrate bias.

  Although lowering the threshold voltage is desirable in terms of reducing power consumption, generally, there is a problem in that frequency characteristics do not increase due to a decrease in driving voltage of an integrated circuit.

  Therefore, until now, as a means for controlling the threshold voltage, an impurity element that uniformly imparts one conductivity is added to the entire channel formation region, and the threshold voltage is controlled by the addition amount. It was common. However, this method still cannot prevent the short channel effect itself, and a punch-through phenomenon has occurred. In addition, the added impurity scatters carriers, which has been a factor of lowering carrier mobility.

  Further, the deterioration of the subthreshold characteristic due to the punch-through phenomenon means that the subthreshold coefficient (S value) is increased, that is, the switching characteristic of the FET is deteriorated. Here, the influence of the short channel effect on the subthreshold characteristic is shown in FIG.

  FIG. 5 is a graph in which the horizontal axis represents the gate voltage Vg and the vertical axis represents the logarithm of the drain current Id, and the reciprocal of the slope (subthreshold characteristic) in the region 501 is the S value. FIG. 5 compares changes in characteristics when the channel length is gradually shortened, and the channel length decreases in the direction of the arrow.

  As a result, it can be confirmed that the slope of the characteristic decreases as the channel length decreases, that is, the S value tends to increase. This means that the switching characteristics of the FET deteriorate as the channel length becomes shorter.

  The above is the explanation of the short channel effect that occurs when the length of the channel formation region of the semiconductor element becomes extremely short. However, when the width of the channel formation region becomes extremely narrow, the phenomenon of the narrow channel effect also occurs. To do.

  FIG. 6 is a cross-sectional view of a general IG-FET cut along a plane perpendicular to the channel direction (direction connecting the source and drain). Reference numeral 601 denotes a single crystal silicon substrate, and reference numeral 602 denotes a field oxide film formed by a selective oxidation method. Individual semiconductor elements used in VLSI are separated from each other by a field oxide film 602.

  Reference numeral 603 denotes a gate electrode, and a channel region 604 is formed by applying a voltage to the gate electrode 603. An impurity region 605 is disposed under the field oxide film 602 and functions as a channel stopper.

  The narrow channel effect is caused by the biting portion (bird's beak) of the field oxide film 602 and the impurity region 605 having a greater influence on the channel region 604 as the channel width W becomes narrower. Specifically, the threshold voltage increases, the effective channel width depends on the power supply voltage, and the like.

  In the current semiconductor industry, semiconductor integrated circuits integrated to the limit are required, and the key is how far down to the miniaturization of individual semiconductor elements can be pursued. However, even if a technique for forming a fine pattern in the deep sub-micron region has been developed, the problem of the short channel effect as described above has been a fatal obstacle that prevents miniaturization of the element.

  The present invention has been made in view of the above problems, and discloses a technique for effectively suppressing the short channel effect accompanying the miniaturization of a semiconductor element. It is another object of the present invention to make it possible to form a fine element in a deep submicron region that has been difficult to realize due to the short channel effect.

The configuration of the invention disclosed in this specification is as follows.
A source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
A gate insulating film and a gate electrode formed on the channel formation region;
An insulated gate semiconductor device having at least
The channel formation region is a region where carriers move,
An impurity region that is artificially and locally formed to pin a depletion layer extending from the drain region toward the channel formation region and the source region;
It is characterized by having.

In addition, the configuration of other inventions is as follows:
A source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
A gate insulating film and a gate electrode formed on the channel formation region;
An insulated gate semiconductor device having at least
The channel formation region is a region where carriers move,
An artificially and locally formed impurity region for controlling to a predetermined threshold voltage by addition of an impurity element;
It is characterized by having.

In addition, the configuration of other inventions is as follows:
A source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
An impurity region artificially and locally formed in the channel formation region;
A gate insulating film and a gate electrode formed on the channel formation region;
In an insulated gate type semiconductor device having at least
An impurity element that broadens an energy band width (Eg) is added to the impurity region.

In addition, the configuration of other inventions is as follows:
A source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
A gate insulating film and a gate electrode formed on the channel formation region;
An insulated gate semiconductor device having at least
The channel formation region is a region where carriers move,
An impurity region that is artificially and locally formed to pin a depletion layer extending from the drain region toward the channel formation region and the source region;
Have
An impurity element that broadens an energy band width (Eg) is added to the impurity region.

In addition, the configuration of other inventions is as follows:
A source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
A gate insulating film and a gate electrode formed on the channel formation region;
An insulated gate semiconductor device having at least
The channel formation region is a region where carriers move,
An impurity region that is artificially and locally formed to pin a depletion layer extending from the drain region toward the channel formation region and the source region;
Have
In the region in which the carriers move, means for preventing carrier impurity scattering or means for preventing mobility lowering due to factors other than carrier lattice scattering are provided.

In addition, the configuration of other inventions is as follows:
A source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
A gate insulating film and a gate electrode formed on the channel formation region;
An insulated gate semiconductor device having at least
The channel formation region is a region where carriers move,
An artificially and locally formed impurity region for controlling to a predetermined threshold voltage by addition of an impurity element;
Have
An impurity element that broadens an energy band width (Eg) is added to the impurity region.

In addition, the configuration of other inventions is as follows:
A source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
A gate insulating film and a gate electrode formed on the channel formation region;
An insulated gate semiconductor device having at least
The channel formation region is a region where carriers move,
An artificially and locally formed impurity region for controlling to a predetermined threshold voltage by addition of an impurity element;
Have
In the region in which the carriers move, means for preventing carrier impurity scattering or means for preventing mobility lowering due to factors other than carrier lattice scattering are provided.

In addition, the configuration of other inventions is as follows:
A source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
By adding an impurity element that widens the energy bandwidth (Eg) in the channel formation region, an artificially and locally formed impurity region;
A gate insulating film and a gate electrode formed on the channel formation region;
In an insulated gate type semiconductor device having at least
The impurity region has an insulating property,
In the channel formation region, the impurity element is not added or added in a very small amount to a region other than the impurity region.

  Note that an impurity element is not added to a region other than the impurity region or is added in a trace amount means that a region (semiconductor layer) for forming a channel is an intrinsic or substantially intrinsic region. .

  Note that an intrinsic region in this specification refers to a region to which an impurity element imparting N-type or P-type and an impurity element such as carbon, nitrogen, or oxygen are not intentionally added. In addition, a substantially intrinsic region is a region in which the conductivity type is canceled without intentionally adding an impurity element imparting N-type or P-type, or a source and a region in which threshold control is possible. It refers to a region exhibiting the same conductivity type as the drain region.

In this specification, an intrinsic or substantially intrinsic region means that the concentration of phosphorus or boron is 5 × 10 ¹⁷ atoms / cm ³ or less, and the concentration of carbon, nitrogen, or oxygen is 2 × 10 ¹⁸ atoms / cm 3. ^An area that is ³ or less.

  In the present invention, examples of the impurity element include carbon, nitrogen, and oxygen.

  In this specification, single crystal silicon is a typical example of a crystalline semiconductor, but this single crystal silicon is, of course, single crystal silicon of a level generally used at the current VLSI and ULSI levels. It also includes higher-level single crystal silicon (ultimately, single crystal silicon in an ideal state as produced in outer space).

  The gist of the present invention is to effectively suppress the spread of the drain depletion layer by the artificially and locally formed impurity region in the channel formation region, and to prevent the punch-through phenomenon and the subthreshold characteristic associated therewith, which has been a problem in the past. It is to prevent deterioration.

  Since the present applicant is similar to forming a pin of an impurity region in a channel formation region, the IG-FET according to the present invention is called a pinning type transistor. In this specification, “pinning” means “suppression”, and “pinning” is used to mean “suppress” or “suppress”.

  It is also an important configuration of the present invention that the threshold voltage drop, which is a typical phenomenon due to the short channel effect accompanying the miniaturization of the channel length, can be mitigated by artificially generating a narrow channel effect. is there.

  FIG. 1A is a schematic diagram of a state when a source region, a drain region, and a channel formation region of a general IG-FET are viewed from above. Note that 101 is a source region, 102 is a drain region, and 103 is a channel formation region.

  A feature of the present invention is that an impurity region 104 is formed in a dot pattern in the channel formation region 103. In the present invention, one or more kinds of elements selected from among carbon (C), nitrogen (N), and oxygen (O) are used as impurities to be added.

The added impurity locally forms an energy barrier having a large energy bandwidth in the channel formation region 103. When carbon, nitrogen, and oxygen are used as in the present invention, the energy band that was in the state shown in FIG. 14A is changed to the state shown in FIG. 14B, and the energy band width (Eg) is increased. Thus, the barrier ΔE becomes a larger barrier ΔE ′. For example, when oxygen is added, it becomes an insulating high resistance region having a structure as shown by SiO _x , which also serves as an electrical barrier.

  In particular, as shown in FIG. 1A, the junction between the drain region 102 and the channel formation region 103 is a region where the electric field changes most drastically. Therefore, it is desirable to arrange the impurity region 104 at this position. In addition, when the electric field due to the gate electrode extends also in the drain region 102, the impurity region 104 can be formed in the drain region 102. Conversely, it is preferable not to form the impurity region 104 in the source region 101.

  As described above, when carbon, nitrogen, or oxygen is used, the impurity region is utilized as an insulating energy barrier in any case, so that it can be shared by the N-channel FET and the P-channel FET. This means that the present invention is advantageous in simplifying the manufacturing process when applied to a CMOS circuit.

  In addition, when the base substrate is silicon, these impurity elements are strongly bonded to silicon atoms and thus are less likely to be re-diffused by heat treatment or the like.

  In addition, the present invention is extremely effective in forming a fine element that requires fine processing in a deep submicron region such as 0.2 μm or less. Accordingly, since the length of the channel formation region (channel length or source / drain distance) is also as short as 0.01 to 1.0 μm, typically 0.01 to 0.35 μm, the impurity region must be cut into a finer pattern. .

  For example, when a resist mask is used when forming a dot pattern-like impurity region, patterning for providing openings in the resist mask cannot use a normal exposure method due to resolution problems. In such a case, a fine pattern may be realized by performing patterning using an electronic drawing method or FIB method.

  Further, since the dot pattern impurity regions are artificially arranged by patterning, not only the arrangement as shown in FIG. 1A but also various arrangements are possible.

  Next, when the insulated gate semiconductor device (IG-FET) having the structure of the source region / channel formation region / drain region shown in FIG. 1A is driven, how the short channel effect is suppressed. This will be described below.

  First, FIG. 1B shows a cross-sectional view taken along A-A ′ of FIG. Reference numeral 105 denotes a field oxide film, and 106 denotes a channel stopper. Although the shape of the impurity region 104 can take various variations depending on the condition setting, here, a case where the impurity region 104 is implanted in a rod shape as an ideal non-scattering example will be described.

  1C is a cross-sectional view taken along B-B ′ of FIG. Reference numeral 107 denotes a field oxide film. Usually, a channel stopper is disposed under the field oxide film, but is abbreviated here. Further, the width of a certain impurity region 104 is represented by wpi, n, and the interval is represented by wpa, m. Here, n and m are wpi, n is the width of the nth impurity region in the channel formation region 103, and wpa, m is an interval between the mth impurity regions (path where carriers move). Means.

  The description so far has only been a description of the structure, but the effect will be described next. First, when a gate voltage and a drain voltage are applied to a semiconductor device having a structure as shown in FIG. 1B, the source-side depletion layer 201, the channel side in the state as shown in FIG. A depletion layer 202 and a drain side depletion layer 203 are formed. That is, the drain side depletion layer 203 has a shape in which the impurity region 204 serves as a barrier to prevent the drain side depletion layer 203 from spreading to the source side.

  Although it is difficult to understand in FIG. 1B, since the impurity region 204 is arranged as shown in FIG. 1A, a model in which the spread of the drain side depletion layer is suppressed by a lattice-like filter that blocks the channel formation region. It ’s easy to understand.

  Accordingly, in the semiconductor device having the structure according to the present invention, as shown in FIG. 2A, the depletion layers are divided without substantially interfering with each other. That is, since the source-side depletion layer 201 and the channel-side depletion layer 202 are distributed without being affected by the drain-side depletion layer 203, the energy state is as shown in FIG.

  That is, unlike the conventional energy state diagram shown in FIG. 5, the energy state of the channel region is controlled only by the electric field due to the gate voltage, and thus has a shape substantially parallel to the channel region. Therefore, there is no problem such as a punch-through phenomenon peculiar to the short channel effect, and a semiconductor device having a high drain breakdown voltage can be configured.

  Further, as shown in FIG. 2A, in the present invention, the volume occupied by the depletion layer is reduced as compared with the conventional one as shown in FIG. The depletion layer capacity is small. Here, the equation for deriving the S value is expressed by the following equation.

  That is, as described above, it can be seen that the reciprocal of the slope in the region indicated by 501 in the graph shown in FIG. Further, the expression of Equation 3 can be approximately expressed as the following expression.

  In Equation 4, k is the Boltzmann constant, T is the absolute temperature, q is the charge amount, Cd is the depletion layer capacitance, Cit is the equivalent capacitance of the interface state, and Cox is the gate oxide film capacitance. Therefore, according to the present invention, since the depletion layer capacitance Cd is sufficiently smaller than that of the conventional one, the S value can be set to a small value of 85 mV / decade or less (preferably 70 mV / decade or less), that is, excellent subthreshold characteristics. Can be obtained.

  Further, the present invention aims to make the depletion layer capacitance Cd and the interface state equivalent capacitance Cit as close as possible to zero. That is, the S value (60 mV / decade) in an ideal state where Cd = Cit = 0 is brought close to.

  In addition, the channel formation region having the structure shown in FIG. 1C is very important in mitigating the decrease in threshold voltage due to the short channel effect. This is because the structure shown in FIG. 1C is necessary for intentionally producing the narrow channel effect.

  For example, focusing on a cross section as shown in FIG. 1C, the width W of the channel formation region is divided by the impurity region 104, and an aggregate of a plurality of channel formation regions having a substantially narrow channel width wpa, m. Can be considered.

  That is, the narrow channel effect is obtained in the region having the plurality of narrow channel widths wpa. When viewed macroscopically, as shown in FIG. 1A, since there is a region where such a narrow channel effect can be obtained in the entire channel formation region, the narrow channel effect can be obtained as a whole, and the threshold voltage is reduced. It is thought to increase.

  Therefore, even if the threshold voltage is lowered due to the short channel effect due to the shortening of the channel length, the threshold voltage can be controlled by intentionally increasing the threshold voltage due to the narrow channel effect for the above reasons. As a result, it is possible to moderate the change in the threshold voltage.

In addition, the configuration of other inventions is as follows:
Forming a source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
Forming a gate insulating film and a gate electrode on the channel formation region;
A method for manufacturing an insulated gate semiconductor device having at least
A region where carriers move relative to the channel formation region;
An impurity region for pinning a depletion layer extending from the drain region toward the channel formation region and the source region;
At least a step of artificially and locally forming.

In addition, the configuration of other inventions is as follows:
Forming a source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
Forming a gate insulating film and a gate electrode on the channel formation region;
A method for manufacturing an insulated gate semiconductor device having at least
A region where carriers move relative to the channel formation region;
And at least a step of artificially and locally forming an impurity region for controlling to a predetermined threshold voltage by addition of an impurity element.

In addition, the configuration of other inventions is as follows:
Forming a source region, a drain region and a channel formation region using a crystalline semiconductor;
Artificially and locally forming an impurity region in the channel formation region;
Forming a gate insulating film and a gate electrode on the channel formation region;
In a method for manufacturing an insulated gate semiconductor device having at least
An impurity element that broadens an energy bandwidth (Eg) is artificially and locally added to the impurity region.

In addition, the configuration of other inventions is as follows:
Forming a source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
Forming a gate insulating film and a gate electrode on the channel formation region;
A method for manufacturing an insulated gate semiconductor device having at least
In order to form an impurity region for pinning a depletion layer extending from the drain region toward the channel formation region and the source region, an impurity element that increases an energy band width (Eg) to the channel formation region is artificially formed. And it has the process of adding locally.

In addition, the configuration of other inventions is as follows:
Forming a source region, a drain region, and a channel formation region formed using a crystalline semiconductor;
Forming a gate insulating film and a gate electrode on the channel formation region;
A method for manufacturing an insulated gate semiconductor device having at least
In order to form an impurity region for controlling to a predetermined threshold voltage by adding an impurity element, an impurity element that broadens an energy band width (Eg) is artificially and locally added to the channel formation region. It has the process.
In addition, the configuration of other inventions is as follows:
Forming a source region, a drain region and a channel formation region using a crystalline semiconductor;
Forming an impurity region artificially and locally by adding an impurity element that widens an energy bandwidth (Eg) in the channel formation region;
Forming a gate insulating film and a gate electrode on the channel formation region;
In a method for manufacturing an insulated gate semiconductor device having at least
The impurity region has an insulating property,
In the channel formation region, the impurity element is not added or added in a very small amount to a region other than the impurity region.

  By utilizing the present invention, it is possible to prevent the short channel effect that occurs when the channel length is shortened. Specifically, the drain-side depletion layer is first blocked from spreading under the source region and the channel formation region by an impurity region locally formed in the channel formation region, and the drain voltage is changed to the energy (potential) state of the channel formation region. The configuration is not affected. As a result, it is possible to prevent the punch-through phenomenon and the deterioration of the subthreshold characteristics. At the same time, a high drain breakdown voltage can be realized.

  In addition, a decrease in threshold voltage, which is one of the characteristics of the short channel effect, can be suppressed by increasing the threshold voltage due to the narrow channel effect. This narrow channel effect can be artificially achieved by the structure of the present invention in which an impurity region is locally formed in a channel formation region.

  As described above, by using the present invention, a semiconductor device in a deep submicron region with a short channel length can be operated without causing a short channel effect. That is, further integration and performance improvement of a semiconductor device represented by IG-FET can be expected.

  In FIG. 1, a region between the source region 101 and the drain region 102 is a channel formation region 103. In the present invention, the impurity region 104 is formed by artificially and locally adding impurities to the channel formation region 103.

  The impurity regions 104 have a dot pattern shape and are arranged with regularity. In the present invention, one or a plurality of elements selected from carbon, nitrogen, and oxygen are used as the impurity added to the impurity region, so that carriers do not pass through the insulating impurity region. That is, a channel region is formed only between impurity regions, and carriers are moved using the channel region as a path.

  When the semiconductor device having the above structure is driven, the drain side depletion layer formed in the vicinity of the drain region 102 is stopped by the impurity region 104 and does not spread laterally (below the channel formation region). That is, since the energy state (potential state) in the vicinity of the source region 101 and the channel formation region 103 is not affected by the drain side depletion layer, each electric field is formed substantially independently.

  Therefore, there is no punch-through phenomenon or sub-threshold characteristic deterioration due to the so-called short channel effect, and a high drain breakdown voltage can be realized.

  The impurity region 104 has a substantially narrow channel width, and a so-called narrow channel effect occurs between the impurity regions 104. Therefore, the decrease in threshold voltage due to the short channel effect can be mitigated or offset by the increase in threshold voltage due to the narrow channel effect.

  The present invention having the above-described configuration will be described in detail with the embodiments described below.

  An example of forming an insulated gate field effect transistor on a single crystal silicon (silicon) substrate using the present invention will be described with reference to FIG. In this embodiment, an example in which a single N-channel FET is formed on a P-type silicon substrate is shown to simplify the description.

  First, reference numeral 701 denotes a P-type silicon substrate, on which a silicon oxide film 702 is formed as a pad oxide film, and a silicon nitride film 703 that functions as a mask for selective oxidation later is formed thereon. The film thickness of the silicon oxide film 702 and the silicon nitride film 703 may be 500 to 2000 mm. (Fig. 7 (A))

  Next, the silicon nitride film 703 is left only in the element formation region by patterning, and ion implantation of an impurity element imparting P-type is performed in that state, and then wet oxidation is performed at a temperature of 1000 to 1100 ° C.

  The silicon surface exposed by this process is selectively thermally oxidized, and a field oxide film 704 is formed as shown in FIG. The field oxide film 704 has a function of insulating and isolating elements from each other.

  The impurity element (B) imparting P-type implanted by the above-described ion implantation process forms a channel stopper 705 under the field oxide film 704. This is a region for preventing a channel from being formed under the field oxide film 704, and usually has the same conductivity as the base substrate (P-type silicon substrate in this embodiment).

  Then, the silicon nitride film 704 and the silicon oxide film (pad oxide film) 705 are removed to obtain the state shown in FIG. In such a selective oxidation step, various selective oxidation methods such as a LOCOS method, a PLANOX method, an Isoplanar method, and a SWAMI method can be used.

  Next, one or a plurality of elements selected from carbon, nitrogen, and oxygen are added to the channel formation region 706 to form an impurity region 707 that serves as a stopper for the depletion layer. The region 707 to which the impurity element is added may be selectively designed by providing an opening in a resist (not shown) by patterning.

  Note that an extremely fine lithography technique is required to make the impurity region 707 into a dot pattern. For this purpose, the dot pattern shape may be exposed using a technique using an electron beam (electronic drawing method) or a technique using an ion beam (FIB method).

  At this time, it is desirable that the spacings wpa, m between the impurity regions 707 are made uniform. This is because variations in threshold voltage (caused by variations in the narrow channel effect) and variations in heat generation (caused by variations in the current density flowing between the impurity regions) may occur.

  When the addition of impurities is completed, a thermal oxidation process is performed to form a thermal oxide film 708 of 100 to 500 mm. The thin thermal oxide film 708 formed by this thermal oxidation process functions as a gate insulating film as it is.

  Further, a polysilicon film 709 is formed as a gate electrode on the oxide film 708 in the channel formation region 706. The gate electrode 709 may be made conductive by adding an impurity element in advance at the stage of film formation. Thus, the state shown in FIG. 7C is obtained.

  After that, as shown in FIG. 7D, an impurity element imparting N-type (P or As) is added, and a source region 710 and a drain region 711 are formed in a self-aligning manner. Thereafter, a silicon nitride film is formed to a thickness of 3000 mm so as to cover the gate electrode 709, and the sidewall 712 is left only on the side surface of the gate electrode 709 by using an etch back method.

  Next, in this state, a titanium film is formed on the entire surface by sputtering, and silicide is formed by means such as heating, laser annealing, and lamp annealing. By this step, titanium silicides 713 to 715 are formed on the surfaces of the source region 710 and the drain region 711 and the surface of the gate electrode 709. Since titanium silicides 713 to 715 have extremely low resistance, they are preferable for ensuring ohmic contact with wirings to be formed later.

  When the silicide formation is completed, a silicon nitride film 716 is formed as an interlayer insulating film, contact holes are formed, and a source electrode 717 and a drain electrode 718 are formed. Thus, an IG-FET having a structure as shown in FIG. 7E is completed.

  The present invention is characterized in that the impurity region is formed in a dot pattern in the channel formation region of the IG-FET, but the dot pattern formation location needs to satisfy a certain range of conditions. This will be described below with reference to FIG.

In FIG. 8, reference numeral 801 denotes a part of the channel formation region. The channel width is W. Here, of the channel width W, the width occupied by the dot pattern 802 is defined as Wpi. As the value of Wpi, for example, 10 to 100 Å is sufficient. If the width of an arbitrary dot pattern 802 is wpi, ₁ , wpi, ₂ , wpi, ₃ ... Wpi _{, n} , Wpi is expressed by the following equation.

  However, in order to achieve the configuration of the present invention, since at least one impurity region needs to be formed in a region other than the end of the channel formation region, n is an integer of 1 or more.

Of the channel width W, the width occupied by the region between the dot patterns (carrier moving path) 803 is defined as Wpa. The value of Wpa can be, for example, 100 to 3000 mm (typically 500 to 1500 mm). Further, if an area 803 between arbitrary dot patterns is wpa, ₁ , wpa, ₂ , wpa, ₃ ... Wpa _{, m} , Wpa is expressed by the following equation.

  However, since at least one impurity region is formed in a region other than the end of the channel formation region as described above, the channel formation region is divided into at least two and m is an integer of 2 or more.

That is, the relationship that the total channel width W is W = Wpi + Wpa and n + m is 3 or more is established. The relationship between W and Wpi, W and Wpa, and Wpi and Wpa preferably satisfy the following conditions at the same time.
Wpi / W = 0.1-0.9
Wpa / W = 0.1-0.9
Wpi / Wpa = 1/9 to 9

  The meaning of these mathematical expressions is that Wpa / W or Wpi / W must not be 0 or 1. For example, when Wpa / W = 0 (synonymous with Wpi / W = 1), the channel formation region is completely blocked with the impurity region as shown in FIG. Become.

  On the other hand, when Wpa / W = 1 (synonymous with Wpi / W = 0), as shown in FIG. 8C, no impurity region is present in the channel formation region, so that the spread of the drain side depletion layer cannot be suppressed. .

  For the above reasons, it is desirable that the relational expressions of Wpa / W and Wpi / W fall within the range of 0.1 to 0.9 (preferably 0.2 to 0.8), and at the same time satisfy Wpi / Wpa = 1/9 to 9. When the channel length is L, the channel formation area is represented by W × L.

  Further, the present invention is effective in improving mobility, which is a representative parameter indicating the performance of the FET. The reason will be described below.

  The mobility is determined by the scattering of carriers in the semiconductor (a silicon substrate in this embodiment), and the scattering in the silicon substrate is roughly divided into lattice scattering and impurity scattering. Lattice scattering has a low impurity concentration in the silicon substrate and is dominant at a relatively high temperature, and impurity scattering has a high impurity concentration and is dominant at a relatively low temperature. The overall mobility μ formed by these influences is expressed by the following equation.

The equation shown in Equation 5 is obtained when the overall mobility μ is affected by the reciprocal of mobility μ _l when _l is affected by lattice scattering ( _l means lattice) and by impurity scattering. This means that it is inversely proportional to the sum of the reciprocal of mobility μ _i ( _i means impurity).

Here, if the drift electric field is not so strong in the lattice scattering, the acoustic phonon plays an important role, and the mobility μ _l at that time is proportional to the −3/2 power of the temperature as shown in the following equation. Therefore, it is determined by the effective mass (m *) and temperature (T) of the carrier.

Moreover, the mobility mu _i due to impurity scattering is proportional to 3/2 power of the temperature as indicated by the following expression and inversely proportional to the concentration N _i of ionized impurities. That can be varied by adjusting the concentration N _i of ionized impurities.

  According to these equations, channel doping in which impurities are added to the entire channel formation region as in the prior art cannot gain mobility due to the influence of impurity scattering. However, since the impurity region is locally formed in the present invention, no impurity is added between adjacent impurity regions (regions having a width of Wpa).

In other words, it means that the closer to 0 without limit concentration N _i of impurities ionized in the number 7 in theory, the mobility mu _i will be approaching infinity as possible. That is, in Equation 5, the impurity is reduced to such an extent that the term of 1 / μ _i can be ignored, so the entire mobility μ approaches the mobility μ _l without limit.

It is also theoretically possible to further increase the mobility mu _l by reducing the effective mass of the carriers (m *). This can be achieved by utilizing a phenomenon in which the effective mass of carriers (especially in the case of electrons) varies depending on the crystal axis orientation in a cryogenic region.

  According to the literature, the minimum effective mass can be obtained when the channel direction connecting the source / drain (the direction in which carriers move) is configured to coincide with the <100> axis direction of single crystal silicon.

  For example, it is assumed that a source region 1502, a channel formation region 1503, and a drain region 1504 are formed on a single crystal silicon substrate 1501 having a (100) plane as shown in FIG. At this time, this corresponds to a case where the channel direction 1505 is set to [100]. However, this example is a result in an extremely low temperature region of 4 ° K.

  In addition, the channel direction and the axial direction (arrangement direction) of the impurity regions 707 and the axial direction of the crystal lattice are approximately parallel (the axial deviation is within ± 10 ° so that carriers can pass through the crystal lattices well). It is desirable to make it fit. In the case of a single crystal, since silicon atoms are regularly arranged, carriers moving parallel to the crystal lattice arrangement direction are hardly affected by lattice scattering.

  For example, when the rotation axis in the above-mentioned direction is 0 ° in the single crystal silicon substrate, the same effect can be obtained in the case of rotation shafts of 90 °, 180 °, and 270 °.

  As described above, carriers that move in the channel formation region pass through regions other than the impurity regions existing in the channel formation region. This will be briefly described with reference to the schematic diagram of FIG.

  In FIG. 16A, reference numeral 1601 denotes a channel formation region. That is, FIG. 16A is a view of the channel formation region as viewed from the upper right. In the channel formation region in which the present invention is implemented, an impurity region 1602 is three-dimensionally formed as shown in FIG.

  An arrow 1603 described in FIG. 16A indicates the traveling direction of carriers (electrons or holes). As shown in FIG. 16A, a plurality of impurity regions 1602 are arranged in the channel formation region 1601, and carriers pass through regions other than the impurity regions 1502.

  When the traveling direction of carriers is viewed from the upper surface of the channel formation region 1601, it looks as shown in FIG. FIG. 16B is a view of the surface represented by ACEF in FIG. From FIG. 16B, it can be seen that the carriers avoid the impurity region 1602 and move in a region without impurity scattering.

  That is, most carriers move between the source / drain through the impurity region 1602 as indicated by the arrows. Of course, the case of moving in a zigzag manner so as to avoid the impurity region is also included.

  FIG. 16C illustrates the channel formation region 1601 as viewed from the side. Note that FIG. 16C is a view of the surface represented by ABCD in FIG. Reference numeral 1603 denotes an arrow, which indicates that the arrowhead is directed toward the front side of the drawing. Also from this figure, it can be seen that carriers move between the impurity regions 1602.

  In this embodiment, an example in which a CMOS circuit in which an N-channel FET (NMOS) and a P-channel FET (PMOS) are complementarily combined using the present invention will be described. Although details of the manufacturing process of the CMOS circuit are omitted here, in the present invention, as described in Embodiment 1, a dot pattern impurity region is formed only in the channel formation region before the gate insulating film is formed.

  FIG. 13A shows a cross section of a CMOS circuit when the present invention is used. FIG. 13A is a cross-sectional view in which a CMOS circuit formed by a general manufacturing method is divided in a channel direction.

  In FIG. 13A, 1301 is an N-type silicon substrate, 1302 is an n-well, and 1303 is a p-well. That is, a P-channel FET (PMOS) is formed on the n-well 1302 and an N-channel FET (NMOS) is formed on the p-well 1303.

  The NMOS and PMOS are separated by a field oxide film 1304 formed by a selective oxidation method, and a channel stopper 1305 is disposed under the p-well side field oxide film.

  Further, an impurity imparting P-type, for example, boron is added to the n-well 1302, and a PMOS source region 1306 and a drain region 1307 are arranged. Further, an n-type impurity such as phosphorus or arsenic is added to the p-well 1303, and an NMOS drain region 1308 and a source region 1309 are arranged.

  In the channel formation region sandwiched between the source region 1306, the drain region 1307, the source region 1308, and the drain region 1309, dot pattern impurity regions 1311 and 1312 are formed before the gate insulating film 1310 is formed in advance. deep.

  The reason why the impurity regions 1311 and 1312 are formed before the gate insulating film 1310 is formed in this embodiment is to prevent damage to the interface between the gate insulating film 1310 and the channel forming region. It is also possible to take a method of adding.

  In this embodiment, oxygen is used to form the impurity regions 1311 and 1312. Therefore, it is not necessary to separately use the NMOS and the PMOS, and they can be shared.

  Further, when a CMOS circuit as in this embodiment is formed, it is desirable to form impurity regions 1311 and 1312 also in the drain regions 1307 and 1308 as shown in FIG.

  For example, when the semiconductor device of the present invention is used for an element in which the source and the drain are switched like a pixel, an impurity region may be formed in both the source region and the drain region.

  Then, gate electrodes 1313 and 1314 made of a conductive material are formed on the channel formation region, and an interlayer insulating film 1315 is formed so as to cover it. Further, a contact hole is formed in the interlayer insulating film 1315, and a PMOS source electrode 1316, a PMOS and NMOS common drain electrode 1317, and an NMOS source electrode 1318 are disposed.

  The CMOS circuit having the structure shown in FIG. 13A can be miniaturized according to the present invention without causing a short channel effect, so that an integrated circuit with a very high degree of integration can be formed.

  It is also possible to form a BiCMOS circuit in which the CMOS circuit shown in FIG. 13A and a bipolar transistor are combined. An example of a BiCMOS circuit formed by utilizing the present invention is shown in FIG.

In FIG. 13B, 1319 is a P-type silicon substrate, 1320 is a buried N ⁺ region, 1321 is a p-well formed by epitaxial growth, and the p-well 1321 on the buried N ⁺ region 1320 is doped N-type. Thus, an n-well 1322 that functions as a collector is formed. Also, 1323 is a DeepN ⁺ region serving as take-out electrode from the buried N ⁺ region 1320.

Reference numeral 1324 denotes a field oxide film formed by a normal selective oxidation method. An n ⁺ region 1325 is formed in the p well 1321, and a p ⁺ region 1326 is formed in the n well region 1322. In the n well 1322 on the side constituting the bipolar transistor, a p ⁻ region 1327 serving as an active base is first formed, and then a p ⁺ region 1328 and an n ⁺ region 1329 serving as an external base are disposed.

An impurity region 1330 is disposed on both the PMOS side and the NMOS side. The impurity region 1330 may be formed after the n ⁺ region or the p ⁺ region is formed, or before that. Of course, any of carbon, nitrogen, and oxygen may be used.

  Then, a BiCMOS circuit is formed by disposing the gate electrode 1331, the interlayer insulating film 1332, and the source / drain wiring 1333. The BiCMOS circuit has a circuit configuration for effectively combining the high-speed operability of the bipolar transistor and the low power consumption of the CMOS circuit.

  In the first embodiment, the shape of the impurity region 707 in the depth direction is described as a rod. However, this is an ideal state as in the case where there is no scattering at the time of implantation. It is also possible to form impurity regions.

  For example, a wedge-shaped impurity region 901 as shown in FIG. 9A may be formed depending on ion implantation conditions. Conversely, a squirrel-like impurity region 902 as shown in FIG. 9B may be formed. In particular, when the shape as illustrated in FIG. 9B is used, adjacent impurity regions below the impurity region 902 are in contact with each other.

  In this state, the channel formation region can be substantially regarded as an SOI structure that is isolated from the bulk substrate. This structure can extremely effectively suppress the drain side depletion layer from affecting the depletion layer in the channel formation region. In addition, an effect of preventing the depletion layer in the channel formation region from spreading downward can be expected.

  In the first embodiment, an example is shown in which dot patterns (impurity regions) are arranged in a matrix as shown in FIG. 1A, but various other arrangement patterns can be obtained by changing the design pattern.

  For example, as shown in FIG. 10A, a pattern in which the impurity regions 1001 are alternately arranged can be used. In this case, since the gap between the dot patterns is compensated by the next row, the lateral expansion of the drain side depletion layer can be effectively prevented. In particular, this is a very effective configuration in the IG-FET in which the influence of the short channel effect is extremely large as in the case where the channel length is 0.1 μm or less.

  However, since the path along which the carrier moves meanders as shown by the dotted line, there is a possibility that the mobility may decrease as the carrier moving distance becomes longer. However, in the region where the channel length is 0.1 μm or less where this structure is effective, the carriers from the source region reach the drain region in an instant, so there is no problem even if the movement distance is substantially increased. Conceivable.

  Therefore, for example, when the channel length is 0.1 μm or more, the dot pattern impurity region is arranged as shown in FIG. 1A, and when the channel length is 0.1 μm or less, it is shown in FIG. It is desirable to arrange in such a way.

  Further, as shown in FIG. 10B, the dot pattern may be an ellipse or a rectangle perpendicular to the channel direction. In this case, the structure is suitable for suppressing the drain side depletion layer. However, since it may interfere with the movement of carriers, it is preferably used for a semiconductor device having a very short channel length of, for example, 0.2 μm or less.

  Further, as shown in FIG. 10C, the dot pattern can be an ellipse or a rectangle parallel to the channel direction. In this case, since the narrow channel effect appears more conspicuously, it can be said that the configuration is effective when it is necessary to increase the threshold voltage excessively.

  The present invention can be applied not only to the lateral IG-FET as shown in the first embodiment but also to IG-FETs having various structures. For example, the lateral IG-FET also includes an LDD (offset) structure (FIG. 11A), a double drain structure (FIG. 11B), a buried channel structure (FIG. 11C), an SOI structure ( FIG. 11D), a SIMOX structure (FIG. 11E), and the like.

  In this embodiment, an N-channel FET is taken as an example, and a case where it is applied to the above structure will be described. Note that N + and N− in the figure relatively indicate the strength of the N-type conductivity, and N + means that the N-type conductivity is stronger than N−.

  FIG. 11A illustrates a structure in which a low-concentration impurity region 1103 is provided between a source or drain region 1101 and a channel formation region 1102. Although the drain-side depletion layer easily spreads as much as the low-concentration impurity region 1103 exists, the spread can be suppressed by the present invention.

  FIG. 11B shows a structure in which a conductive region 1105 having a width of 0.1 to 0.5 μm is formed on the side surface of the source or drain region 1104. The source or drain region 1104 and the conductive region 1105 have the same conductivity, and the conductivity of the conductive region 1105 is weaker. For example, the source or drain region 1104 can be formed by implanting As (arsenic), and the weak conductive region 1105 can be formed by implanting P (phosphorus).

  The embedded channel structure shown in FIG. 11C is often formed as a result of forming a CMOS circuit with an N-channel FET and a P-channel FET, and the short channel effect is also affected. Easy structure.

  Structurally, for example, in an N-channel FET, a conductive region 1107 that is the same and weak as the source / drain region 1106 is formed near the interface of the channel formation region.

  Therefore, a channel is formed immediately below the conductive region 1107. Even in such a case, the short channel effect is suppressed by implementing the present invention, and the punch-through phenomenon and the threshold voltage are reduced. Can be prevented.

  In addition, the SOI structure is a technology that has been developed including the purpose of reducing the depletion layer by thinning the semiconductor layer used as an element, and thus has the effect of suppressing the short channel effect itself. For example, the structure shown in FIG. 11D is generally called an SOS (silicon-on-sapphire) structure, and is formed by growing a silicon single crystal on a sapphire substrate 1108.

  However, it is difficult to form a single crystal silicon layer having a thickness of 1 μm or less, and there is a limit in suppressing the spread of the depletion layer. Therefore, if the present invention is applied to an SOI structure, the short channel effect can be prevented more reliably.

  Note that FIG. 11E shows an example in which an IG-FET is formed over a substrate that is included in the same SOI structure but is generally called SIMOX (separation-by-implanted oxygen). In this case, the buried oxide layer 1110 is formed by implanting oxygen into the single crystal silicon substrate 1109. In addition, an extremely thin single crystal thin film can be formed by reducing the oxygen implantation depth.

  Even in such a case, the present invention can be used. In this case, an effect of suppressing (pinning) the drain-side depletion layer from spreading to the channel formation region can be expected.

  In the present invention, as a means for forming the impurity region in the channel formation region, a method using the property that impurities are segregated into strain is possible in addition to the patterning method using a resist mask.

  First, the same state as in FIG. 7B is obtained according to the procedure of the first embodiment. That is, in FIG. 12A, 1201 is a silicon substrate, 1202 is a field oxide film, and 1203 is a channel stopper.

  In this state, a localized anisotropic etching process is performed on the surface of the silicon substrate using a focused ion beam or the like to draw a groove-like or hole-like pattern 1204 in a desired shape at a desired position. (Fig. 12 (A))

  Next, an impurity element such as nitrogen is added to the entire surface of the substrate 1201. Of course, carbon or oxygen may be used. This impurity element is for forming an impurity region later. The implantation depth is preferably deeper than the depth of the groove-like or hole-like pattern 1204. (Fig. 12 (B))

  When the addition of the impurity element is completed, heat treatment is then performed at a high temperature of about 1000 to 1200 ° C. By this heat treatment, a thermal oxide film 1205 is formed on the side wall of the groove or hole pattern 1204, and the groove or hole pattern 1204 is embedded. Therefore, this region becomes an oxide region 1205 substantially represented by SiOx. In this case, it is preferable to perform the heat treatment in an oxidizing atmosphere because the formation rate of the oxide region 1205 increases.

  At the same time, the impurity element added to the entire silicon substrate 1201 is segregated in the oxide region 1205. This occurs because the impurity element segregates due to large strains, lattice defects, or the like generated in the vicinity of the oxide region.

  Through the above process, the impurity element is segregated in the peripheral portion of the oxide region 1205 and becomes the impurity region 1206.

  In the case where an impurity element imparting one conductivity such as phosphorus or boron is added to the single crystal silicon substrate 1201, when the thermal oxide film forming the oxide region 1205 is formed, boron is a thermal oxide film. It is taken in and phosphorus tends to be expelled (pile up) at the oxide film / silicon interface.

  By effectively utilizing such an effect, it is possible to effectively suppress a decrease in mobility due to impurity scattering.

  In addition, for example, using a device that can perform ion implantation without a mask such as a focused ion beam, oxygen ions are directly implanted onto a single crystal silicon substrate, and heat treatment is performed to oxidize the ion implanted region. It is also possible to transform into a physical area. In addition to the focused ion beam, an electron beam or the like may be used.

  In this embodiment, an example in which a semiconductor device using the present invention is incorporated in a product (electronic device) is shown. Here, an explanation will be given by taking an IC circuit incorporated in a notebook personal computer as an example. The description will be given with reference to FIG.

  In FIG. 17, reference numeral 3001 denotes a main body, 3002 denotes a lid portion, 3003 denotes a keyboard, and 3004 denotes an image display portion. Various integrated circuits 3005 are incorporated in the main body 3001.

  When the integrated circuit 3005 is taken out, the outside is covered with a package 3011 and the internal semiconductor chip is protected with resin or the like. Also, the internal semiconductor chip is connected to the outside by leads 3012. Normally, the integrated circuit (IC chip) 3005 to be seen is completely a black box because only the black package 3011 and the lead 3012 are visible to the outside eye.

  When the semiconductor chip protected by the package 3011 is taken out and viewed, for example, it has the following configuration. First, an arithmetic unit (processor) 3014 and a memory unit 3015 are arranged on the substrate 3013. Reference numeral 3016 denotes a bonding portion for connecting the semiconductor element and the lead 3012.

  The arithmetic unit 3014 and the memory unit 3015 are configured by using various other circuits such as a CMOS circuit, a BiCMOS circuit, a DRAM circuit, and an SRAM circuit. The configuration as shown in FIG. 15 shown in this embodiment is characterized in that the arithmetic unit 3014 and the memory unit 3015 are arranged on the same substrate.

  When the arithmetic unit 3014 and the memory unit 3015 are adjacent to each other as described above, data is exchanged between the arithmetic unit 3014 and the memory unit 3015 at a very high speed. It becomes possible to form.

  In addition, since all necessary circuits can be integrated on a single chip, it can be expected that the manufacturing cost will be greatly reduced. Furthermore, it is possible to reduce the size of the product by reducing the arrangement area.

  By using the present invention, it is possible to reduce the size of a semiconductor element without causing a short channel effect, so that the semiconductor electronic device can be further miniaturized and ported by using it in combination with the above-mentioned one chip. it can.

  The present invention can be applied to various semiconductor electronic devices other than the example shown in the seventh embodiment. This is because the electrical characteristics of the semiconductor device according to the present invention are very excellent, and an IC circuit configured using this can achieve high frequency characteristics.

  The device characteristics of a single semiconductor element formed by using the present invention are very excellent. The threshold voltage Vth, n of an N-channel FET is -0.5 to 3.0 V, and the threshold value of a P-channel FET. The voltage Vth, p can be adjusted in accordance with the required driving voltage in the range of -3.0 to 0.5 V. The S value is 60 to 85 mV / decade, preferably 60 to 70 mV / decade.

Further, high mobility (1000 cm ² / Vs or more) can be obtained for the reason described in the first embodiment. When the mobility is obtained by a calculation formula, it should be noted that the mobility is inversely proportional to the channel width W. When the present invention is carried out, the channel width is not limited by the impurity region in the channel formation region. Therefore, actual mobility cannot be obtained unless the measured channel width Wpa is substituted.

  When an IC circuit is configured with the semiconductor device of the present invention capable of achieving the above excellent electrical characteristics, extremely good frequency characteristics can be obtained. For example, when a nine-stage ring oscillator is configured using the semiconductor device of the present invention, a frequency characteristic of 2 to 10 GHz can be realized with a driving voltage of 3.3 V.

  For example, the present invention is also effective for an electronic device that requires high frequency characteristics, such as a mobile phone that is a high-frequency electronic device. An IC circuit used for an input unit of a cellular phone or the like requires a frequency characteristic of 2 GHz, but the present invention can sufficiently cope with such a high frequency IC circuit.

The figure which shows the structure of a channel formation area | region. The figure which shows the structure of a channel formation area | region. FIG. 6 is a diagram for explaining a conventional semiconductor device. The figure which shows the energy state of a channel formation area | region. FIG. 6 is a diagram illustrating characteristics of a conventional semiconductor device. FIG. 10 shows a structure of a conventional semiconductor device. 4A and 4B illustrate a manufacturing process of an insulated gate field effect transistor. The figure for demonstrating the formation conditions of an impurity region. The figure which shows the shape of the depth direction of an impurity region. The figure for demonstrating the shape and arrangement | positioning of an impurity region. The figure which shows the structure of an insulated gate field effect transistor. 10A and 10B illustrate a manufacturing process of an impurity region. The figure which shows the structure of an insulated gate field effect transistor. The figure which shows the energy state of a channel formation area | region. The figure which shows the structure of a channel formation area | region. The figure which shows the structure of a channel formation area. FIG. 10 illustrates an application example of a semiconductor device.

Explanation of symbols

101 Source region 102 Drain region 103 Channel formation region 104 Impurity region (dot pattern)
105 Field oxide film 106 Channel stopper

Claims (5)

A gate insulating film disposed on the semiconductor, and a gate electrode disposed on the gate insulating film,
The semiconductor has a channel formation region;
The channel formation region and the gate electrode are disposed at overlapping positions,
A semiconductor device, wherein a plurality of impurity regions are formed in a dot pattern in the channel formation region. In claim 1,
The impurity region is squeezed,
The semiconductor device according to claim 1, wherein the impurity regions adjacent to each other below the impurity region are in contact with each other. A semiconductor disposed on an insulator, a gate insulating film disposed on the semiconductor, and a gate electrode disposed on the gate insulating film;
The semiconductor has a channel formation region;
The channel formation region and the gate electrode are disposed at overlapping positions,
In the channel formation region, a plurality of impurity regions are formed in a dot pattern,
The semiconductor device is characterized in that the impurity region is in contact with the insulator. In any one of Claims 1 thru | or 3,
A semiconductor device, wherein the impurity region contains one or more elements selected from carbon, nitrogen, and oxygen. In any one of Claims 1 thru | or 4,
The semiconductor has a source region and a drain region,
The semiconductor device, wherein the channel formation region is disposed between the source region and the drain region.

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