JPS59138333A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce the movable ion concentration in an insulative film substantially by using an alloy selected from two specified groups of metal as a metallic film for electrodes as well as performing high temperature treatment in the atmosphere including H2 gas. CONSTITUTION:An silicon oxide film 2 for isolating elements and an oxide film 3 for gates are formed on a surface of an Si substrate 1. Next, an alloy film 7 made of metals selected from a group consisting of Cr, Mo and M and a group consisting of Ti, Zr, Hf, V, Nb and Ta is formed on said films 2 and 3. Then, this film 7 is coated with a mask material and is subjected to photolithography to form an alloy gate electrode 8. Next, an impurity ion showing the reverse conductivity type to the substrate 1 is implanted with using the electrode 8 as a mask, thereby forming a source region 5 and a drain region 6 for an MOS transistor. Thus the concentration of movable ions in the insulative film is substantially reduced and deterioration of the characteristics caused by movement of the movable ions can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Use) The present invention relates to a method for manufacturing a semiconductor device in which the density of mobile ions in an insulating film in contact with electrode wiring is reduced.

(Prior art) In recent years, so-called self-aligning element formation methods used for high-melting metal electrodes and wiring have been used to more efficiently integrate electrodes and wiring inside semiconductor devices. I started to get carried away. ? In the self-aligned element formation method for MO8 type circuits, a film such as molybdenum (MO), which is a melting point metal, is used as a mask for impurity ion implantation into the semiconductor substrate, and it is also used as a mask for impurity ion implantation into the semiconductor substrate. Use as electrodes and wiring.

This process will be explained with reference to the drawings at the top of the MOS transistor section. As shown in Figure 1(a), S
Two sil oxide films for element isolation are formed on the l substrate 1, and three oxide films are further formed on the substrate 1. Thereafter, as shown in FIG. 1(b), a high melting point gold maple film for electroplated wiring, for example MO, is deposited and processed by photolithography to form four gate electrodes. .Next, as shown in Figure 1(C), S
Impurity ion cation that shows the transmission type opposite to the l substrate l *
A source region 5 and a drain region 6 of a MOS transistor are formed by implanting the electrode 4 using a Z mask. Thereafter, impurities are activated by heating at 1000° C. with reeds in a nitrogen atmosphere.

In this process, the gate electrode 4t mask is used to align the ion implantation into the source directly mounted 5 and the train chain acid 6. In addition, the images of the impurity diffusion region and the opening wiring are aligned. / ζ will not be forced to praise fL without seeing it. As a result, the area occupied by the prime is reduced, and the area occupied by the pellet (V) is increased to form a larger number of sounds.

When this self-aligned element formation method is used, the thin film serving as the gate electrode acts as a mask for the impurity ions to be implanted, and is heated to an extreme of 1000 C. It is reassuring to know that you have the 7 qualities of endurance. M
(In the JS type integrated circuit, impurity-doped polycrystalline S1 has traditionally been used as this twisted electrode/self-wire. However, its specific resistance is about 5 x 10-'Ω-a1
As a result, the resistance of the arrangement portion increases due to the finer structure of electrodes and wiring, and signal propagation delay due to this increase in resistance becomes a problem. For this reason, recently, the technology used for electrodes and wiring made of high-melting point metals such as MO, which has a specific resistance of impurity-doped polycrystalline 5iLV), which is about 2 times lower, has been attracting attention. For example, in MO, the crystal grain size is smaller, so microfabrication is possible, and -! In addition, since the atomic code is 42 and the bulk density is as large as 10.21/cm-3, the blocking ability against ion implantation is also high.

However, when a 14OS transistor is actually manufactured for use in MO electrodes and wiring, the phenomenon that the threshold voltage fluctuates over a long period of use subsides.

This phenomenon manifests itself conspicuously as a negative change in the threshold voltage during all VC bias temperature acceleration tests.

General l/civi OS type integrated circuit's? IVI
The threshold 1ilI% and pressure stability of U.S. transistors are the most important issues in terms of the reliability of the performance circuit.
The above variations are not tolerated. Many studies have been conducted on the cause of this threshold voltage fluctuation, and it is mainly due to the movement of ions of alkali metals such as Na in the oxide film. I don't know. These mobile ions were initially created as impurities in the metal. Furthermore, with the addition of contamination on the surface of the metal electrode in the manufacturing process paste, it is thought that some of the metal may have diffused and invaded the oxide film during processes such as tube temperature heat treatment. .

Regarding the reduction of mobile ions in the gated film, conventionally,
I have been trying to figure out ψ using various methods. The first method involves placing all the phosphorus (P) in the oxide film and fixing it on the oxide film insulating the phosphorus (P) by utilizing the linking effect of Na caused by PVC. In this case, the general method is to deposit the VCP-containing silicate glass on the 1c gate electrode by butter nintering, and then diffuse it into the P-cate oxide film in the silicate glass through a quick heat treatment. There is. In this method, Pc/)4 people are carried out by thermal diffusion.
) to trap and precisely confine its introduced chain plate into the catenate oxide film.
It is not possible to control 1l-i each station.

In particular, in the case of a 1VLO S type semiconductor device which has become more stable, the thickness of the gate oxide film becomes as thin as 300^ or less, making it even more difficult to control P diffusion.

The second method includes the still-temperature hydrogen treatment method reported by Ishikawa et al. and Yanagawa et al. for MO electrodes formed by vapor deposition.
o.

H, Tokunaga, N, Toyokura,
F. Yanagawa.

K., Kiuchi, and M., KOndO:
IEEE 'l'rans.

Electron Devices, Vol, ED
-27, pp, 1586-1590.198U, ,
F, Y'anagawa, K, 1 (iuchi
.

T, l-1osoya, T, Tsuchiya,
T, Amazawa, and T-fVlano:
IEEE 'l'rans, Electron]
)evices.

Vol, ED-27, pp, 1602-1606.
1980). In this method, heat treatment is performed at 1000°C in a mixture of slag (H2-1'J+ (10% - 90%)) after butter contouring, or heat treatment is performed at T100°C in a N2 atmosphere. After doing , pull@ followed by N
2 Heat treatment at 1000°C in N2 mixed gas is planned.

As a result, the mobile ion illuminance in the categorized film is 1O~
It decreases by 1 to the extent of lO. However, when this method is applied to a sputtered MO film, the degree of impurity in the sputtered metal film is higher than that in a vaporized film, so the effect of reducing the riJ ion density by this heat treatment alone is not sufficient. be. When depositing an MO film by sputtering, adding 6≦H2 gas to Ar gas for sputtering results in Hll-
During heat treatment in N2 mixed gas, the fall of b'-mobile ions is δ.
It is known that it will become even stronger.
955). However, in this case, a high temperature heat treatment tray of about 1000°C is required, and at 900°C the temperature is still 10'.
. Mobile ions with a density of about cm-2 can be detected.

On the other hand, with regard to one block of melting point metal for a cathode electrode, techniques for adding other areas in other areas have been developed in order to improve the unique characteristics limited to the problem of mobile ions.

For example, for MO, Teta 7 (Ti) yz 2
A method of mixing up to 15 Wt% is known (Japanese Patent Publication No. 35868/1983).

In this case, the membrane weir Ijy,v is partially covered with a Ti plate, and the sputtering method is mainly used. With this method, the adhesion to the substrate is increased compared to the MO film. However, the numerical value of the mobile ion density by these methods has not been reported.

(Objective of the Invention) The present invention is proposed to improve all the above-mentioned drawbacks.
4 (7) r, possible jllJ-1 on! To provide a method for manufacturing a semiconductor device that reduces PJ time. This is the purpose.

(Pt of the invention) In order to achieve all of the above objects, the present invention includes a step of forming an insulating film foot on the surface of a semiconductor substrate, and a gamma gold ingot selected from the group consisting of chromium, molybdenum, and tungsten on the glare insulating film. , titanium, zirconium, hafnium, vanadium,
No. 2, a mixed film with a gold ingot selected from the group consisting of tantalum - 1 - The mixed film or the public gold film is patterned to form a 1kL electrode. - The gist of the invention is a method for manufacturing a semiconductor device which includes a step of forming wiring and a step of performing high-temperature heat treatment in an atmosphere containing hydrogen gas.

Next, an embodiment of the invention will be explained with reference to a trend drawing.

The Jaku example is just one example, and it goes without saying that Yuzu's sorrow or improvement can be made without departing from the +5b bright Kozue God.

FIG. 2 is an explanatory drawing of the gate electrode portion of the IVfO8 type semiconductor device according to the invention, and shows the cross-sectional shape of the surface of the MO8 type semiconductor device according to the invention. First, as shown in the second section (a), a Si blinding gland 2 for element isolation and a catoxide film 3 are formed on the surface of the Si substrate 1. In the present invention, the following process shown in FIG. 2(b) is different from the conventional process. That is, conventionally lo-3 to 10-2' [or
For example, MO-z sputter link 1-7) or ~10-
The MO film for the cathode 11L electrode was formed by depositing Mo 7z electron beam evaporation in a vacuum at a pressure of 7.5 x 10
” MO metal and Ta (tank/I/) targets were simultaneously sputtered in an Ar gas atmosphere at a pressure of Torr, and a 3300A thick M
A public metal electrode film 7 of O and Ta is deposited. Tatashi,
If the substrate is not sufficiently heated (for example, to 700° C. or higher) during sputtering, the combination of MO and Ta is insufficient at this point, and the film is generally a mixture of MO and Ta. However, it is alloyed by the subsequent still-temperature heat treatment.

In this example, for convenience, the film immediately after deposition will also be referred to as a public gold film. In this example, sputtering was used for film deposition, but electron beam evaporation may also be used. It is also possible to use MO and TaO metals as the target or the deposition source. In addition, these methods are carried out in an Ar gas atmosphere or in a vacuum, but is there H2 gas in the atmosphere? ]l-It doesn't matter if you add it. ? In the sputtering method, the partial pressure of gas is k 2 x 10'-1
0-' Torr shall be 8 degrees. The name of this Lugas is
As shown later, f't-
I have something to do.

In addition, as in this implementation, with the aim of lowering the resistance of the electrode, MO with low resistivity (bulk resistivity 5
．． Th (bulk resistivity 1.3XlO-5) has a relatively high resistivity as an additive metal.
Ω-ffl)? In the case of an assembly machine using r, add T.
The concentration of a is the total resistivity of the public gold film after heat treatment lX1O
-'Ω-a or less, it is desirable to set it to 1 Oat, % or less.

After this, as in the conventional process, as shown in FIG. 2(C), a masking material such as @photoresist is applied onto the alloy gate electrode film 7, and processed by photolithography to form the alloy gate electrode 8.
form. Next, as shown in FIG. 2(d), impurity ions having a conductivity type opposite to that of the substrate 1 are implanted using the alloy gate electrode 8 as a mask to form a source region 5 and a drain region 6 of the MOS transistor. .

In the present invention, the subsequent steps are also different from the conventional method.

That is, conventionally, in order to activate impurities implanted into the source/drain regions, 1,000 ml of impurity was applied in an N2 gas atmosphere.
A heat treatment session was carried out at a temperature of about ℃. However, in the present invention, this heat treatment is performed in an atmosphere containing N2 gas. For example, if the total N2 gas is 10%, then 90 parts of N2 gas is added to 1 atm of N.
2- 1oooc in N2 mixed gas.

Heat for 30 minutes. In addition, this heat treatment is performed first with N
Heat treatment at 1000° C. may be performed in a two-gas atmosphere, followed by heat treatment at 1000° C. in an N2-Nx mixed gas atmosphere. The heat treatment temperature is 700℃.
Fully loaded at higher temperatures.

As explained above, the basic principle of the invention is to use an alloy selected from two specific metal groups as the metal film for the electrode, and to conduct all high-temperature heat treatment in an atmosphere containing N2 gas. It is a feature.

Next, the mobile ion v2 degree characteristics of the MOS capacitor manufactured based on this example will be explained using the drawings. FIG. 3 shows that a MOS capacitor with a gate electrode shape of 500 pm was formed by depositing a gate electrode of 40 OA on a p-type Si substrate by sputtering using the process steps shown in this example. Moving ions! [Nrll-TVS method (
Triangular Voltage Sweep M
There are seven results measured using method) f. The horizontal axis indicates the temperature of heat treatment in N2-N2 mixed gas performed after electrode formation. The vertical axis represents the mobile ion density Nm' in the gate oxide film. In the figure, "MO" indicates a sample of an MO gate! pole formed using a conventional technique.
A sample of the alloy gate electrode of "N2-Mo-
Ta" is DJlo and Ta's companion Kate Kai & film formation snow ivy gas (Ar: partial pressure 7.5 x 10-"T
orr ), the H2 gas f partial pressure is 2 X 1O-3 Torr
Sample tap water was prepared by adding 7JI so that r. In the conventional C gate electrode, when the heat treatment temperature is 1000°C, vc + mobile ion @ degree Nm is about 10" crn-2. Compared to this, with the MO-Ta gate electrode according to the present invention, even at 900°C It has a small a of about 10"cm-", and furthermore, at 1000℃, I x 10"+1ff-"
The following is true. Furthermore, for the Hz Mo-Ta gate electrode, the decrease in mobile ion density is even more pronounced at p, 900°C.
However, it remains undetectable. From these results, MO
It should be confirmed that the addition of Tal7) to the Ivy gas, as well as the addition of 0 gas to the Ivy gas, greatly promotes the reduction of the mobile ion density Nm due to the heat treatment V in the L-N2 mixed gas. 'L'fc0 As shown in the above examples, in addition to the conventional heat treatment in an atmosphere containing N2 gas, an alloy film is used for the gate electrode as in the present invention, and furthermore, an electrode film formation process is performed using a gas atmosphere. By performing this in an atmosphere of
It has become clear that it is possible to reduce the detection limit to below "cvr-".

In this example, an MO-Ta alloy was used for the gate electrode, but this alloy has a relatively low resistivity among high melting point metals and has a relatively low resistivity (at room temperature) of Lt7! The first suppressive metal consists of Cr (chromium) and MOLW (tungsten), which absorb a small amount of nitrogen gas, and 'l'i (titanium), which has a relatively high resistivity and a large absorption amount of N2 gas at room temperature. ,Zr
<zirconium), 1 (f (hafnium), ■ (vanadium), Nb (niobium), Ta and S (for example, Ta and W) can be selected as appropriate. The effect of reducing the mobile ion density Nm during heat treatment in a mixed gas of 12-N and 12-N, without significantly impairing the electrical conductivity of the metals of the first group. It is possible to promote all.

Although this embodiment deals with a MOS type semiconductor device, the gate insulating film is not limited to Si oxide, and may be made of general MIS (Metal-Jnsular).
The present invention can be applied to semiconductor devices of the type (or-8 semiconductor). Furthermore, it is clear that the present invention can be used not only for MIS type semiconductor devices but also for passivation insulating films for bipolar type semiconductor devices and the like.

(Effects of the Invention) As explained above, according to the present invention, γL is made of metal selected from a solution consisting of Cr1M0IW, Ti, zr, and 1-4t for electrodes and wiring on an insulating film of a semiconductor device.

If the electrode is made of an alloy with a metal selected from the group consisting of V, Nb, and 'l'a, and this alloy electrode is heat-treated at high temperature in an atmosphere containing hydrogen gas, the movable material contained in the insulating film can be removed. The total ion density can be significantly reduced.

Therefore, in the semiconductor device manufactured in this manner, the characteristic deterioration caused by the movement of mobile ions observed during the bias-temperature acceleration test is significantly improved. Therefore, the present invention has the effect of significantly improving the fineness of a semiconductor device.

[Brief explanation of the drawing]

Figures 1 (a) to (c) are enlarged sectional views of main parts for explaining the entire manufacturing process of a conventional MOS transistor, and Figure 2 (a)
~(d) are enlarged sectional views of essential parts for explaining the entire manufacturing process of the MO8 type semiconductor device according to the present invention, and FIG. 3 is a H2-N2
This is a characteristic diagram showing the relationship between heat treatment temperature and mobile ion density in a mixed gas. l...Si substrate 2... Si [chemical film 3...] for isolation between elements...
......Cate oxide film 4...Gate electrode 5...Source region 6...Drain region 7... ...Alloy cate electrode film 8...
...Gold-containing gate electrode! +! f Applicant Nippon Telegraph and Telephone Public Corporation Figure 1 6 Figure 2 Figure 3 900 1000

Claims (2)

[Claims] (1) A step of forming an insulating film on all six sides of the semiconductor substrate, and coating a metal selected from the group consisting of chromium, molybdenum, tank stainless steel, and titanium on the insulating film. A film mixed with a metal selected from the group consisting of zirconium, hafnium, vanadium, niobium, and tantalum, or an alloy film of the same type. A method for manufacturing a semiconductor device, which includes a step of patterning to form electrodes and arrangements, a step of performing still-temperature heat treatment in a dark atmosphere in which water deposits are present, and a step of forming an electrode/arrangement. (2) The process of forming the mixed family or alloy film is carried out in an atmosphere containing aqueous gas. ! A method for manufacturing a semiconductor device according to Jt.