JPS5884462A - Metal oxide semiconductor type semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To lower voltage applied to a depletion layer between a drain and a gate, to elevate junction breakdown voltage, to thin a gate insulating film and to miniaturize a circuit by forming a section in the vicinity of at least the drain of the gate insulating film by an insulating film having a low dielectric constant. CONSTITUTION:The second insulating film 6b is deposited onto the whole surface, and the second insulating film 6b is also buried to overhang sections 7a, 7b as shown in the figure C. If Si3N4 is used as the first insulating film 6 at that time, SiO2 having a dielectric constant lower than that of Si3N4 is employed as the second insulating film 6b. When the second insulating film 6b deposited onto the whole surface is removed through anisotropic etching through which side etching such as reactive ion etching is hardly generated, the second insulating film 6b is left in the overhang sections 7a, 7b as shown in the figure D, and the gate insulating film 6 of composite constitution of which the second insulating films 6b, 6b having the low dielectric constant are flatly arranged at both sides of the first insulating film 6a is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an MO8 hollow semiconductor device with an improved structure of a dirt insulating film and a manufacturing method K11 thereof.

Conventionally, as shown in FIG. 1, impurities are diffused into a semiconductor substrate 1 to form a source 2 and a drain 3.
A dirt electrode 6 is provided on the substrate surface above the channel region between the source 2 and the drain 3 with a dirt insulating film 4 interposed therebetween.

In recent years, with the miniaturization of such MOB semiconductor devices, a so-called sheet channel effect has been occurring. One way to improve this problem is to increase the impurity concentration of the semiconductor substrate 1, reduce the dielectric depth Xj, and thin the r-to insulating film 4, which is a so-called scaling method. .

However, when the junction depth XJ is made shallower and the dirt insulating film 4 is made thinner, a new problem arises in that the junction breakdown voltage is reduced. This junction breakdown occurs near the drain 3 and dirt where the electric field is concentrated, and the larger the difference between the drain 3 and f- voltages (generally r-), the higher the drain voltage when the voltage is OV.
The voltage difference between r and
The thinner the film thickness is, the lower it becomes.

For example, P (i'o o) silicon substrate (specific resistance 2Ω
a11), XJ = 0.31im s? ) Oxide film thickness 400! , r-) When the voltage O,v, the breakdown voltage is about 10 V (defined as 10-''A), and the substrate and !, are under the same conditions,
ff-) If the oxide film thickness is as thin as 200X, the jumper 1/breakdown voltage will drop by about 5VKffi, and if noise margins are taken into account, it will not be possible to withstand the use of a 5V power supply voltage. This was a major hindrance to development.

The present invention was made in view of this point, and
A MOB ml semiconductor device and its manufacturing method in which the gate insulating film is made thinner and circuits miniaturized by lowering the electric field applied to the depletion layer between f and T and increasing the dif/custom breakdown voltage. It provides:

That is, in the present invention, on the channel region between the source and the drain,
MOB with dirt electrode provided through gate insulating film! 1
In the single conductor device, at least the vicinity of the drain of the dirt insulating film is formed with an insulating film having a lower dielectric constant than other parts. The first summary is the MOB '11 semiconductor device.

The present invention also provides a step of providing a first insulating film on a semiconductor substrate, a step of depositing a dirt electrode material directly above the tenth insulator, and f-) simultaneous turning of the electrode material.
After turning for a period of time, the first insulating film is side-etched to form an overhang part, and a second insulating film having a lower dielectric constant than the first insulating film is formed on the overhang part. forming a source and a drain under the second insulating film having a low dielectric constant of the dirt insulating film; The second gist is a method for manufacturing a MOBg semiconductor device, which is characterized by comprising steps of forming a MOBg semiconductor device.

Furthermore, the present invention includes a step of providing a patterned first insulating film on a semiconductor substrate, and using the first insulating film as a mask.
Further, a step of providing a 20th insulating film having a different dielectric constant on the exposed semiconductor substrate using a masking material provided on the substrate as a mask,
The insulating film was turned into a composite 111 layer.
a step of forming a dirt insulating film; a step of providing a dirt electrode on the dirt insulating film; MO8r1 characterized in that it consists of
The third gist is a method for manufacturing an i-semiconductor device.

The present invention will be explained in detail below.

In the present invention, a first insulating film which is a constituent element of a gate insulating film having a composite structure, and a second insulating film having a different dielectric constant from this
As the insulating film, for example, 815N4 e 8102
, 'TaO2, etc. '* As a combination of first and second insulating films having different dielectric constants, for example, 8
1. N4 and 5SO2 (permittivity ratio approximately 7=4), or T
aO2 and 81. There is a combination with N4 to form a drain under the insulator with a lower dielectric constant.

j! The method for forming the first and second insulating films is as follows:
The dirt electrode may be formed by depositing an insulator or by oxidizing or nitriding the surface of the substrate. Examples of the material for the dart electrode in the present invention include polycrystalline silicon, single crystal silicon, amorphous silicon, metal silicide, and metal. is used.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 shows an embodiment of the present invention.
4), after forming an element region and a field region (not shown) on a semiconductor substrate 1 such as a P (100) silicon substrate, a first insulating film 6 is formed on the element region.
1k) Next, after depositing dirt electrode material on this, it is turned to form f-) electrode 5.

Next, when the first insulating film 111ja is etched using the dirt electrode 5 as a mask, the tenth insulating film 6a located under the gate electrode 5 is side-etched, as shown in the side of the figure, and an overhang portion 1 m + is formed. 7b
is formed. In the case of etching, the first insulating film 6 may be etched at the same time as the dirt electrode material is patterned.

After this, the second insulation #6b is deposited on the entire surface (see the same figure).
ni show t yo5 K% oh ai-/% y/wAy a
.

7bK is also embedded in the second insulating film 6b. In this case, for example, if the first insulating film is aεa t813N4, then 5to2, which has a low dielectric constant, is used as the second insulating film 6b.

Next, anisotropic etching such as reactive ion etching, which hardly causes side etching, is used to remove the entire W.
When the second insulating film 6b deposited with K is removed, the second insulating film 6b remains on the overhang part 7a*7b as shown in [1@], and the dielectric constant is increased on both sides of the first insulating film 6&. A gate insulating film 6 having a composite structure is formed in which second insulating films 6b, 6b having a low temperature are arranged in a plane.

Next, a second insulating film 6 having a low dielectric constant of the dirt insulating film 6 is formed.
Impurities are diffused into the semiconductor substrate 1 below the semiconductor substrate 1, 6b, and the source 2 and drain 3 are formed.
It is assumed to be an O811 semiconductor device.

Part 3 regarding the operation of the Mo5rIi conductor device with the above structure.
This will be explained with reference to the figures.

The dirt voltage is Ov.
When they get close, the boundary a between the drain 3 and the channel region
I explained earlier that it occurs near &. This is because the electric field applied to the depletion layer 9K in the semiconductor substrate 1 is strongest near the boundary 8m. Therefore, in order to increase the junction breakdown voltage, it is necessary to reduce the electric field applied to the semiconductor substrate 1. By the way, simply speaking, the voltage applied to the semiconductor substrate 1 is connected in series between the capacitance of the depletion layer 1 and the capacitance of the r-to insulating film 6.
It is determined by the capacitance division of the key I dacitance. Therefore, if the dielectric constant of the gate insulating film 6 is made small, this key/4
The capacitance is also small, and the proportion of the voltage applied to the oak depletion layer 9 appears small, resulting in an increase in the junction breakdown voltage.

However, if the entire gate insulating film 6 is formed of an insulating film with a low dielectric constant, the junction breakdown voltage increases, but the overall key passivation of the r-to insulating film 60 decreases.

The characteristics of the MO811 semiconductor device are determined by the capacitance of the dirt insulator AG, and reducing the capacitance by lowering the dielectric constant effectively has the same effect as increasing the thickness of the r-diaphragm film. This goes against miniaturization methods such as rings. Therefore, as in the present invention, it is preferable to partially form the part near the drain 3 where the electric field is the strongest, that is, the 20th insulating film 61 of the dirt insulating film 6, with an insulator having a low dielectric constant. This makes it possible to increase the dielectric breakdown voltage without significantly reducing the characteristics.

In the above embodiment, the method of forming the dirt insulating film 6 by utilizing side etching of the first insulating film 6m to form a composite structure will be described below.

First, as shown in Figure 4), an element region and a field region are formed on a semiconductor substrate 1, and then a first field region is formed on the element region.
An insulating film 61 is then formed. Next, a masking material 10 such as a resist is deposited on the first insulating film 6a, and then patterned. Using this as a mask, the first insulating film 6a is etched as shown in FIG. 10 Expose the surface.

Next, as shown in the figure, a second insulating film 6b having a lower dielectric constant than the first insulating film 6a is deposited over the entire surface.

After this,) the masking material 10 which has been turned
Then, the second insulating film 6b deposited thereon is peeled off to form a dirt insulating film 11g having a composite structure as shown in )K in the figure.

Hereinafter, after depositing the r-) electrode material to form the r-) electrode 5, the steps for forming the source 2 and drain S are the same as those in FIG. 2 of the above embodiment.

FIG. 5 shows another method. First, as shown in item 59), a first insulating film 6a having oxidation resistance or nitridation resistance is formed on the surface of the semiconductor substrate l.

Next, the first insulating film 6a is patterned.
1), the surface of the semiconductor substrate 10 is exposed. Thereafter, using the patterned first insulating film 6a as a mask, a second insulating film *gb having a lower dielectric constant is grown on the exposed surface of the substrate by oxidation or nitriding. ), a dirt insulating film 6 having a composite structure is formed. As an example of applying such a method, the first insulating film 6a is Ill,! 'J4 and 8102 is used as the second insulating film 6b.

The steps for forming the dart conductor 4I5, the source 2, and the drain 3 to produce the MOS fi semiconductor device shown in FIG. 3 are the same as in the previous embodiment.

Note that if the first insulating film CaK does not have oxidation resistance or nitridation resistance, a masking having oxidation resistance or nitridation resistance is formed on the first insulating film 6a as shown in FIG. 6(A). Material 10 is deposited and/or turned. Next, using this as a mask, as shown in FIG. 1), a second insulating film 6b having a low dielectric constant is grown on the exposed substrate surface, and then the masking material 10 is peeled off.

In all of the above embodiments, the first insulating film 6 has a high dielectric constant.
Although the method of forming the layer a first has been shown, the reverse method may be used as shown in Diagram 7 of the irises.

First I! As shown in FIG. 7), a second insulating film gb having oxidation resistance or nitridation resistance is provided on the entire surface of the semiconductor substrate 1 (D), and is patterned to form an Ill pattern on the surface of the substrate.

Next, using the patterned second insulating film 6b as shown in FIG. -) forming an insulating film 6; Thereafter, the dirt electrode 4, the source 2, and the drain 3 are formed to fabricate the MO8fi semiconductor device in the same manner as the stone mason II.

Note that if the second insulating film 6b does not have oxidation resistance or nitridation resistance, a masking material 10 having oxidation resistance or nitridation resistance is applied on the second insulating film 6b as shown in FIG. The first insulating film 6a may be deposited and patterned, and then used as a mask to grow the first insulating film 6a on the exposed substrate surface, as shown in Φ) in the figure, to form the f-) insulating film 6 of the composite structure.

In each of the above methods, f-) MO811 semiconductor device having a composite structure as shown in FIG. 3 is manufactured. The device will be explained.

FIG. 9 shows that on both sides of a first insulating film 6a with a high dielectric constant, there are second insulating films 6b, σb, which are thicker and have a lower dielectric constant.
is arranged to form a stepped insulating film 6.

@10ffFi, j1!9 Contrary to what is shown in Fig. 9, the thickness of the second insulating film 6b was made as thin as possible to reduce the jumper breakdown voltage drop, and a dirt insulating film 6 with a composite structure was used. It is something.

Further, in FIG. 11, both ends (source/drain side) of the first insulating film 6a with a high dielectric constant are formed thin, and a second insulating film 6b with a low dielectric constant is laminated on this thin part. is flattened, and the dielectric constant is lowered only in the vicinity of the source 2 and drain 3 as a whole.

In FIG. 12, a first insulating film 6a with a high dielectric constant is formed over the entire r-meter electrode 5 with the same width, and only in the vicinity of the boundary 8a #Jlb between the source 2 and drain 3 and the channel region. , a dirt insulating film 6 is used in which a twentieth insulating film 6b having a low dielectric constant is locally provided to have a striped O composite structure.

FIG. 13 shows a modification of FIG. 12, in which a second insulating film 6b with a low dielectric constant is locally provided only in the vicinity of the boundary 8a between the drain 3 and the channel region, resulting in a composite structure f-) Insulation The membrane 6 is used.

Furthermore, FIG. 14 shows a dart with a composite structure in which a first insulating film 6a with a high dielectric constant is provided on the source 2 side, and a second insulating film 6b with a low dielectric constant is provided adjacent to this on the drain 3 side. An insulating film 6 is used.

In the above embodiments, the first insulating film Iia is described as having a high dielectric constant, and the second insulating film 6b is an insulating material having a low dielectric constant. If the structure is such that an object is located, the first insulating film 6
*t - low dielectric constant, second insulating film ebt@high electric constant - may be used.

As explained above, according to the MO8 type semiconductor device and the manufacturing method thereof according to the present invention, since at least the vicinity of the drain of the dirt insulating film is formed with an insulating film having a low dielectric constant, the depletion layer between the drain and the dirt is formed. By lowering the voltage applied to the circuit and increasing the breakdown voltage, it is possible to make the dirt insulating film thinner, thereby making it possible to miniaturize the circuit.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a conventional MOS M semiconductor device, and FIG.
3 is a cross-sectional view showing the steps of manufacturing a semiconductor device in sequence, FIG. 3 is a cross-sectional view for explaining the operation of the MOa type semiconductor device of FIG. 2, and FIGS. Cross-sectional views showing the process of manufacturing a gate insulating film, FIGS. 5 (G) to (C), FIGS. Hiroo in different ways on PC
9 to 14 are cross-sectional views showing the process of manufacturing dart insulating films, respectively, in which dart insulating films with different composite structures are
FIG. 2 is a cross-sectional view of an MO8 board semiconductor device. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 2... Source, 3... Drain, 4... Dirt insulating film, 5... f-) electrode, 6a
...first insulating film, 6b...second insulating film, 1a,
Fb...overhang part, 8aelb...II field, Ri...depletion layer, 10...masking material. Applicant's agent Patent attorney Takehiko Suzue-10/a Figure 3 Figure 7

Claims (5)

[Claims] (1) In an MO8 type semiconductor device in which a dirt electrode is provided on a channel region between a source and a drain via a dirt insulating film, at least the vicinity of the drain of the dirt insulating film is insulated with a low dielectric constant from other parts. A MOB type semiconductor device characterized in that it is formed of a film. (2) providing a first insulating film on the semiconductor substrate;
A step of depositing a gate electrode material on this first insulating film, a step of turning this dirt electrode material to form an f-) electrode, and a step of forming an f-) electrode. -) A process of side etching the first insulating film to form an overhang part after Fii4 turning which is performed simultaneously with the patterning of the electrode material, and forming a second insulating film having a lower dielectric constant than the first insulating film. The step of providing the conjunctival membrane on the overhang portion, and the step of providing the conjunctival membrane on the overhang portion; 1 and 2 insulating films) are turned into a composite structure f
f-) A MOS li characterized by comprising a step of forming an insulating film, and a step of forming a source or a drain under the 20th insulating film having a low dielectric constant of the dirt insulating film.
! Semiconductor device 0 manufacturing method. (3) f-) The first and second insulating films constituting the insulating film are formed by depositing an insulating material or by oxidizing or nitriding the surface of the substrate. A method of manufacturing the MO811 semiconductor device described. (4) A step of providing a first insulating film with arm-turning on the semiconductor substrate, and using the first insulating film as a mask, t
or forming two series of insulating films with different dielectric constants on the exposed semiconductor substrate using a patterned asking material provided thereon as a mask, and patterning the first and twentieth insulating films to form a composite structure. a step of forming a dirt insulating film on the CHI'-) insulating layer; 1. A method for manufacturing a MOB ml semiconductor device, comprising the step of forming a drain. (5) Claim 4 is characterized in that the insulating films Ill and 2 constituting the dirt insulating film are formed by depositing an insulating material or by oxidizing or nitriding the substrate surface. MOB IIIml semiconductor device manufacturing method.