JPS62216271A - Mis type semiconductor device - Google Patents

Abstract

PURPOSE:To form an isolation region easily by shaping a source region, a drain region and a channel forming region by a semi-amorphous semiconductor and forming the isolation region by an amorphous semiconductor. CONSTITUTION:A source region, a drain region and a channel forming region are shaped by a semi-amorphous semiconductor, and an isolation region is formed by an amorphous semiconductor. Accordingly, density at a recombination center is reduced by 1/10<2>-1/10<4> as 10<13>-10<16>cm<-3>, and electric conductivity is increased by 10<4>-10<6> times as 10<-6>-10<-4>OMEGAcm<-1>, and the semiconductor device is brought close to an ideal semiconductor, thus acquiring the value of 1-50mum under the intermediate state between 300Angstrom of AS and -10<3>mum of CS in the mobility of electrons and holes.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a structure that is intermediate between an amorphous structure and a crystalline structure (including single crystal and polycrystalline) and is stable in terms of free energy. The present invention relates to an MIS type semiconductor device using semi-amorphous (hereinafter referred to as SAS) having a third state.

[Conventional technology and its problems]

Conventionally, amorphous silicon semiconductors (hereinafter referred to as AS) have been defined by having random interatomic distances and random crystallographic coordination.

Also, by being random in every sense of the word,
In terms of free energy, crystalline semiconductors (CRYSTALLI)
NE SEMICONDUCTOR (hereinafter referred to as CS) is not necessarily more stable than AS
Due to its randomness, there were many unpaired bonds that were not chemically bonded to others. This unpaired bond becomes the center of recombination, extremely shortening the lifetime of the carrier, and is the most anticipated carrier killer to eliminate. Recently, as a method for removing this dangling bond, neutralization with hydrogen or halogen is known. In other words, assuming that the semiconductor is silicon, Sj・+H・ → 5t−H 3i・10F・ → 5t−F is known. ing. Silane (SiHt), silicon tetrafluoride (S
iF4) or a gas mixture thereof using a glow discharge or plasma CVD method, the recombination center density is 1020 to 10220111″3 for AS without the addition of hydrogen or halogen. 10''~10I10l9' and 10
It is attracting attention as a method that can reduce the density of recombination centers to 1/10'.

However, such a density was not sufficient for a semiconductor. Therefore, AS was not suitable for semiconductors. The present invention improves the density of such recombination centers from 10" to 1
0110l6' and further 1/102 to 1/10',
Also, the electrical conductivity is 10-6 to 101Ω1 and 104 to 1
As a result, the mobility of electrons and holes is 1 to 50 μm, which is between 300 μm for AS and ~103 μm for C8. I was able to get

The object of the present invention is to apply a semi-amorphous semiconductor having the above properties to an MIS type semiconductor device.

[Means for Solving the Problems] The present invention provides a solution by forming a source region, a drain region, and a channel forming region with a semi-amorphous semiconductor, and forming an isolation region with an amorphous semiconductor.
The isolation region can be easily formed due to the difference in electrical conductivity between the semi-amorphous semiconductor and the alpha semiconductor, and has the following characteristics.

The present invention is defined as a semiconductor having a semi-amorphous semiconductor (semi-amorphous) structure, and regarding a semiconductor device in which such a semiconductor and an amorphous semiconductor are placed adjacent to each other, a semiconductor with such an intermediate structure is referred to as a semi-amorphous (hereinafter referred to as SAS). , an amorphous semiconductor (hereinafter referred to as AS) is locally controlled, and in particular, the conductivity of the SAS is made to be larger than that of the AS.

The present invention allows a current, particularly a pulse current, to flow through a specific path in AS in combination with energy of optical excitation by light irradiation or thermal excitation by heating, thereby allowing the current to pass through recombination centers due to dangling bonds. The feature is that the state of the material is frozen (quinched) by local multi-heating and rapid cooling at such locations due to recombination of the two, especially by this extremely rapid cooling when the current is stopped. In other words, the normal interatomic distance is established by activating this dangling bond and bonding it with another dangling bond nearby or with a bond neutralized by other hydrogen, etc. A semi-amorphous semiconductor (St! MI-AMO
RPHOIIS SEMICONDIICTOI? In other words, it is related to S to S).

The present invention relates to a semiconductor such as silicon, Si.
+ St ・ → St −3tS
In addition to physically causing reactions such as i. It is characterized by promoting the rearrangement of

Examples of the present invention are shown below.

〔Example〕

[Example 1] This example shows the present invention and mainly describes the manufacturing principle and existence theory of SAS.

Figure 1 shows that a conductor or semiconductor electrode (3) (referred to as M) is selectively formed on an insulating substrate (4) with an amorphous structure, and a semiconductor (1) (semiconductors are collectively called S (called AS or S) and a counter electrode (called AS or S) and a transparent electrode made of translucent metal or ITO (
2) (hereinafter referred to as M) is a vertical cross-sectional view of an MSM structure having the configuration.

In the drawings, this embodiment shows a semiconductor mainly composed of silicon (1
), firstly silane (St84), 5i
F4. % 5iHzC1z or the like to a thickness of 0.1 to 10 μm, particularly 1 to 5 μm, by a glow discharge method or a plasma CVD method. The semiconductor film may be formed using a sputtering method, a vacuum evaporation method, or a reduced pressure CVO method. Also AS
To mix 1 to 50% of SAS in AS in the GROWN state, or to approach 100χSAS, or to make part of it SAS, the temperature should be 30% higher than the crystallization temperature.
Heating is performed at a temperature of 450 to 700°C, which is ~150°C lower, and the atmosphere is Hc! : Mixed state with He, e.g. SiH*: 10-30%, Hz: O-10χ, He
:90-60% 1-100M11z or 1-10G
It was sufficient to generate plasma using induction energy having an output of 300 W to 3 KH at a frequency of H2. He has a high ionization voltage and a high concentration among all atoms, and in order to maintain a plasma state, it also has a thermal conductivity of 0.123 Kcal/mHrc, 0.0398 for neon, 0.0140 for argon, and 0.00 for nitrogen.
Since the content of all gas elements is larger than that of 0206 etc., it was particularly important for carrying out a soaking reaction.

A further object of the present invention is to improve the probability of the existence of SAS in this AS to make it an As GROWN semiconductor with approximately 100.chi. of 95% or more.

Furthermore, before and after the step of forming this semiconductor, electrodes (3) and (2) made of semiconductor electrodes doped with a large amount of metal or impurities or impurity electrodes are formed by vacuum evaporation, plasma CVD, or low pressure CVD. The structure shown in FIG. 1 was obtained. Furthermore, the voltage is applied to these two electrodes in the forward direction to 1.0 m2 ~ 5 x 104 people/cm.
A current, particularly a pulse current, was applied by applying it for 100 seconds, particularly 0.01 to 2 seconds, in the range of 1.

This current may be applied multiple times between the electrodes (3) and (2) by charging a capacitor of 10 to 10'PF and discharging it.

At this time, when AS is not doped with impurities, the electrical conductivity (hereinafter referred to as σ) is 10-9 to 10-"Ωcm-', which is equivalent to insulating properties. However, in particular, when light is irradiated in a spot shape, 10'L to the size of 1μφ to 1mmφ in the part
If the illuminance is greater than or equal to X, the electrical conductivity σ at that location is 1.
It increases by 106 times from 0-1 to 10-6 Ωcm-'. It has been found that by using these photocarriers, a large current can be passed only in this part, making it possible to form an SAS, and furthermore, since no current flows in the area adjacent to it, the AS structure remains.

Furthermore, regarding the characteristics of this SAS, an example will be shown.

Figure 2 shows the electric conductivity σ on the vertical axis in LOG coordinates,
The horizontal axis shows the absolute temperature.

Curve (10) is the electrical conductivity characteristic of AS, and 3
When XIOA/cm" and 103A/cm2 are applied for 0.5 seconds, the curves change to (11) and (12), respectively, and the electrical conductivity is 10-"Ωc of AS at room temperature.
m-', 10-' to 10-4 Ωcm-' and 10
It was found that it can be increased by as much as 4-106 times.

Furthermore, As and sb, which are metallic impurities, are added to this AS.
Characteristics (10') of AS to which 0.1 to 10 mol%, for example 1.2 mol%, of V-valent impurities such as Gas In, ■-valent impurities such as Sn and Pb are added When the current for SAS is applied, the curves (13) and (14
) was able to be obtained.

From this, the following ■, ■, and heptavalent metallic elements are SAS
It acts as an auxiliary agent to promote this, and its properties are completely different from impurities such as B and P, which do not have an auxiliary effect.

Furthermore, the increase in electrical conductivity due to SAS is expressed as ESR (
According to the measurement results of the spin density of the dangling bond by electron spin resonance), the application time was 0.1 seconds (17) and 0.5 seconds.
If you change and add seconds (16) and 2.5 seconds (18),
As shown in FIG. 3, we were able to obtain curves that all gradually decreased with respect to the current density.

That is, the number of dangling bonds is reduced by forming SAS, the electrical conductivity is further improved, and the carrier mobility is 103 to 1.
It turned out that the improvement was 0.6 times.

However, when electron beam diffraction images are taken of these semiconductor films, no crystallized structure can be discerned, and crystallographically it can be said that they do not have a crystal structure and are amorphous.

Further, although the hydrogen content was 20 mol% in AS, the amount decreased to only about 0.1 to 5 mol%. Therefore, it is considered that the ESR result is not due to the hydrogen neutralizing the unpaired bonds, but due to the neutralization due to the S+ comrades bonding with each other.

From the above characteristics, in contrast to the structure in which the interlattice distances and positions of the so-called AS film are random, this is different from the crystal structure, which is stable in free energy and stable in terms of thermal energy. It is assumed that it has a third stable point in terms of free energy. Figure 4 shows this relationship, and the concept is a general C0NFIGU.
RATIONAL C00DINATE (Coordinates in phase space) The vertical axis indicates free energy. In the drawing, A
S (21), (21”), 5AS (22), C
3 (23) and 3 states, SAS is from AS to C8
It turned out to be a third stable state rather than a metastable state.

In addition, in this Figure 2, the substrate temperature is 200°C from room temperature.
, 400℃, the room temperature graph (11), (1
2) could be obtained at low current densities (11) of 3 A/cm" or 10" A/am2, respectively. Generating photocarriers by localized light irradiation when applying current, and scanning this light spot
It is a feature of the present invention that the SAS can be created according to the scanned optical path. At this time again,
At the same time, promoting thermal excitation by heating was not unreasonable in practical terms, and was extremely effective in uniformly applying current to a wide area.

This current density means the average current in this area.

It means the current density in the region where the current flows locally under the electrode, so it is not only the small area of 1 mm or less.
, 10 cm'.

In FIG. 1, the semiconductor (
20) becomes SAS', and since there is no lower electrode in area (19), the 8S of AS GROWN or AS and SA
S semiconductor mixed with S, area (19") is AS GR
It has an intermediate structure between the OWN semiconductor and the region (20) semiconductor.

This figure 1 shows the case of amorphous silicon, but Ge, G
eSix (0<X4), 5iOz-X (0<X<2)
, SiC1-x (0<X<1)+5iJ4-x (0<
Compounds or mixtures where X<4) can be used in the same manner, and it goes without saying that the term "semiconductor" as used in the present invention includes semi-insulators in the sense that current can flow therethrough.

Thus, although the carrier mobility in silicon, which is AS, was only about 300, it was increased to 1 to 50 μm, which is 10' times as much, and it was able to approach 1/10 to 1/1000 of that of a single crystal.

Further, when a semi-amorphous semiconductor was examined by electron beam diffraction, the interatomic distance was 2.2 to 2.5 people in silicon, which roughly corresponds to 2.3 people in a single crystal. However, such a distance does not necessarily have a crystalline diamond structure like a single crystal, and even if a diamond structure can be formed in the short range order, there is a lot of lattice distortion in the range examined by diffraction.

Due to this lattice strain, the transition of light is different from the indirect transition of single-crystal silicon, and is a direct transition, similar to AS, and it has been found that semi-amorphous semiconductors have an ideal semiconductor structure.

[Example 2] This Example 2 is an MIS-
It is related to PET.

The drawing shows an SO3 type, in which an AS semiconductor layer is formed on an insulating substrate (40) having a so-called amorphous surface formed by forming an oxide film with a thickness of about 1 μm on a glass, ceramic or silicon substrate. Furthermore, a part of it is selectively made into SAS, and this SAS is used as a 1'll5-FET (41), and the rudder is placed in an unsolation region (46).

(46') was used.

That is, 0 produced by the method shown in Example 1,
0.2 silicon nitride (42) for a rudder with a thickness of 3-1 μm
It was formed to a thickness of ~0.5 μm and used as a mask coating.

This silicon nitride is a film that selectively acts as a mask against oxidizing gases.

Next, a selective oxide film (49) was formed by oxidizing and burying As.

Furthermore, after this, this mask film is removed and the gate insulating film (42) is coated with AS again by high pressure or plasma oxidation method.
, (42°) was formed to a thickness of 50 to 100 people. Furthermore, the gate electrodes (41) and (41') are connected to AS or S.
Formed as AS. In particular, when making SAS, conductive metals such as Sb and As are used for N-type, and I for P-type.
nz Ga was added in an amount of 0.1 to 5 mol %. Thereafter, this semiconductor layer was photoetched to produce source and drain electrode leads (50), (50°), and (50°'). After this, in the case of N-channel MIS-FRT,
The source (43L (43')
, drain (44), and (44') regions were doped. The output (drain) electrode lead is an overcoat film (interlayer insulation film) for the VDD lead (50).
(48) is formed on the top, and a pulse current is applied according to Example 1 to form channel forming regions (45), (4
5°) as SAS, and at the same time sources (43) and (43'
), drains (44) and (44') were also made into SAS. However, the As under the insulating film (49) where no current flows
(46).

(46') remains as As, selectively AS and SAS
can be made in the same semiconductor layer, making SAS act as a semiconductor14) and AS substantially act as an insulator.

To make load (41)' a depression type (
The gate of the driver (41) is of N" type, and the gate of the driver (41) is of P type, which is different from the conductivity type of the source and drain. This shows an embodiment of DIS-PET using majority carriers.

When using minority carriers, N channel number 1s-PHT
In the channel forming regions (45) and (45'
) should be P type.

This embodiment is an example of an MIS-FET inverter, but this is integrated, and bipolar IC, SIT
It is also possible to apply the present invention to , IIL, etc. In that case, the transistor and diode regions may be SAS, and part or all of the surrounding isolation region may be ^S. According to the present invention, it is possible to easily change from AS to SAS by simply applying light and electric current, so regions with different conductivities can be easily formed.

Therefore, an isolation region can be easily formed.

As is clear from the above explanation, providing the ^S and SAS of the present invention in the same semiconductor is compatible with the implementation specifications of the Mi
Applications are possible to s-type photoelectric conversion devices, integrated circuits using old 5-PET, optical memories, etc., and many other applications based on the same technical idea are possible.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a semiconductor device for explaining the present invention in detail. Figure 2 shows the resulting electrical conductivity. Figure 3 shows the ESR results. Figure 4 shows free energy in terms of AS, SAS, and C5. FIG. 5 shows the Mis-FIST of the present invention provided on the same substrate with an inverter structure.

Claims (1)

[Claims] A MIS type semiconductor device characterized in that a source region, a drain region, and a channel forming region are made of a semi-amorphous semiconductor, and an isolation region is made of an amorphous semiconductor.