JPH02239624A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To inhibit the corrosion of a metallic wiring, and to prevent disconnection by etching an aluminum base conductive layer to a specified pattern through a reactive ion etching method, etching a high melting-point metallic conductive layer and forming the metallic wiring. CONSTITUTION:A TiW layer 2a, an AlSi layer 3a and a resist layer 4 are shaped onto a silicon substrate 1, A plasma generator is operated, and the AlSi layer 3a is etched to a predetermined pattern through reactive ion etching while using the layer 4 as a mask. The etching cross section of the layer 3 is treated by a plasma atmosphere in a plasma device, and a fluorine base polymer film 5a is shaped onto the etching cross section of the layer 3. The plasma device is operated, the TiW layer 2a is etched while employing the layer 4 as a mask, the etching cross section of the layer 2 is treated by the plasma atmosphere, a fluorine base polymer film 5b is formed onto the etching cross section of the layer 2, and the layer 4 is removed and a large number of metallic wirings 6 running parallel and having line width of 0.8mum and line intervals of 0.8mum are shaped. Accordingly, disconnection can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a method for manufacturing a semiconductor device. More specifically, the present invention relates to an improved method for manufacturing metal wiring using reactive ion etching.

(Example) Conventional technology In the past, metal wiring in VLSIs was fabricated by forming an aluminum-based conductive layer such as ^QSi%A&SiCu on a silicon substrate, or a reaction between silicon and aluminum occurred at the contact part. Since the conductivity of contact metal gradually decreases, it has become necessary to interpose a titanium-based or tungsten-based refractory metal-based conductive layer as a barrier metal between the silicon substrate and the aluminum-based conductive layer. Microfabrication of laminated structure wiring consisting of a conductive layer and an aluminum-based conductive layer is performed using photolithography technology using reduction projection exposure and the following (1) to (3).
Reactive ion etching ( R t E1Reactive 1 ) is performed sequentially in three steps as shown in
It is manufactured by making full use of the on-etching technology.

(1) Reactive ion etching of upper layer aluminum alloy Reactive ion etching of aluminum alloy
4. , BCQs, CQt gas, etc., containing at least chlorine in the molecule, and in addition to this, in order to improve various etching properties, C H F s, CF. The reaction is carried out by adding a fluorocarbon gas such as chlorofluorocarbon gas or an inert gas such as s H e s Ar and the like, and the reaction is roughly expressed by the formula (1).

Al2+ 3 CQ-・-・゜゜yo・＾12ce3(
[ ) (2) Reactive ion etching of the lower barrier metal The lower barrier metal requires the use of chlorine-based gas to accurately etch it. For example, CQ*1B
In order to further improve the etching characteristics such as etching speed and selectivity with the base, enzymes, SF6, CF etc. can be used with the above gases.
4th prize will be added.

(3) Corrosion prevention treatment for aluminum wiring Corrosion prevention treatment for aluminum wiring is carried out by CF. This is done by removing chlorine-based reaction products that cause aluminum corrosion that adhere to the wafer by fluorine radicals in a plasma atmosphere using a wafer.

(c) Problems to be Solved by the Invention Metal wiring made of an aluminum metal layer laminated with a high melting point metal layer interposed on a silicon substrate manufactured by the conventional semiconductor device manufacturing method corrodes due to the corrosion prevention treatment. There is a problem in that corrosion cannot be sufficiently prevented, and corrosion progresses and wires are likely to break.

The present invention was made to solve the above-mentioned problem, and it is an object of the present invention to provide a method for manufacturing a semiconductor device that can suppress corrosion of metal wiring and prevent disconnection.

(2) Means for Solving the Problems This invention provides that the cause of the corrosion is a trace amount of chlorine-based reaction products remaining on the surface (including the side surfaces) of the wiring when the layered structure wiring is etched by reactive ion etching. reacts with moisture that has entered the semiconductor surface to form a current path,
Based on the idea that a current equal to the contact electromotive force flows between the aluminum-based conductive layer and the high-melting point metal-based conductive layer, and the aluminum is corroded by electrochemical action, we conducted extensive research on the relationship between etching parameters and the corrosion. As a result, as shown in Fig. 8, the aluminum-based conductive layer CAQS
When the i layer) is etched by reactive ion etching, a deposit 7 is generated on the etched cross section (A (side wall of the 2Si layer 3a), and the amount of the deposit 7 is
The inventors have discovered the fact that, in the range of -260V to -160V, the smaller the voltage on the negative side, the greater the number of corrosion occurrences, and as shown in FIG. 9, the greater the amount of deposits, the fewer the number of corrosion occurrences.

According to this invention, a resist layer with a predetermined pattern is formed in advance on an aluminum-based conductive layer laminated on a silicon substrate with a high-melting-point metal-based conductive layer interposed therebetween, and the resist layer is applied in a plasma generator. The aluminum-based conductive layer was etched into a predetermined pattern using a reactive ion etching method as a mask, and a fluorinated polymer film was formed on the etched cross section of the aluminum-based conductive layer by plasma treatment using a fluorinated hydrocarbon compound. There is also provided a method for manufacturing a semiconductor device, characterized in that the refractory metal-based conductive layer is then etched again using a reactive ion etching method to form a metal wiring.

In this invention, a resist layer having a predetermined pattern is formed in advance on an aluminum-based conductive layer laminated on a silicon substrate with a refractory metal-based conductive layer interposed therebetween. The high melting point metal conductive layer is a barrier metal for preventing a reaction between the silicon substrate and the aluminum conductive layer, and is made of high melting point metals such as molybdenum, tungsten, tantalum, titanium, and niobium, and these high melting point metals. It can be formed on a silicon substrate by sputtering or the like using alloys of, silicides, nitrides, etc. to a film thickness of usually 0.05 to 0.40 .mu.m. The aluminum-based conductive layer is for forming a metal wiring integrally with the high-melting point metal-based conductive layer, and is made of, for example, AQSisA12SiC.
It can be formed to a film thickness of usually 0.5 to 1.0 μl on the high melting point metal-based conductive layer by a spatter method or the like using U or the like. For the resist layer, a resist solution is applied onto the aluminum-based conductive layer by, for example, the Subin coating method, and after drying this applied layer, when a negative resist is used, a resist solution is applied onto the aluminum-based conductive layer in a manner similar to the layout of the metal wiring to be fabricated. When using a positive type resist for the pattern, expose the pattern to the same pattern as the intended non-placement area of the metal wiring by, for example, reduction projection exposure, and leave the resist of the intended metal wiring placement area using a phenomenon liquid and remove the non-placement area. It can be formed by removing a portion of the resist. The resist solution is, for example, a photoresist, an electron beam resist,
X-ray resists, deep ultraviolet resists, ion beam resists, etc. can be dissolved in an organic solvent and adjusted to a desired viscosity before use.

In this invention, the aluminum-based conductive layer is etched into a predetermined pattern by reactive ion etching using the resist layer as a mask in a plasma generator. The plasma generating device is a device for etching the aluminum conductive layer, forming a fluorine polymer film on the etched cross section, and etching the high melting point metal conductive layer, for example, by keeping the pressure constant. It may be constructed by installing a flat electrode connected to a high frequency power source and a counter electrode opposite to the flat electrode connected to the high frequency power source inside a processing chamber having an exhaust means for maintaining the temperature and a gas introduction means for introducing the reactive gas. In the reactive ion etching method, for example, the aluminum-based conductive layer forming substrate is placed on the electrode of the plasma generating device, the inside of the device is kept in a vacuum state, and the electrode is exposed to a high frequency of usually 13.56 MHZ. is applied to the gas introduction means, for example, SICC4SBCl.
Etching the aluminum-based conductive layer using the resist layer of the substrate as a mask by a chemical reaction caused by radicals generated by introducing a gas such as 23 or C4 and a sputtering action of ions accelerated by the electric field in the dark part of the cathode. I can do it. As a result of this etching, chlorine-based corrosive reaction products adhere to the etched cross section of the aluminum-based conductive layer, but it is not necessary to remove this adhesion, but for example, CF. It is preferable to remove the metal wiring by plasma treatment using , SF6, etc., since this can further improve the corrosion resistance of the metal wiring.

In this invention, a fluorine polymer film is formed on the etched cross section of the aluminum conductive layer by plasma treatment using a fluorinated hydrocarbon compound. The fluorocarbon compound is a raw material for the fluorocarbon polymer coating, and is suitably one that can form a polymer coating in a plasma state, such as C H F s, CH. F
! , CH3F, CHF. -CF3,CHPt-CHFt
, CH. P-CHF,,CI. F- CH, F, CH
3-CHF, CF,=CH. ,CH,=CHF,C
F, -CH=CH,, CH. (Cold) tcF! CI3 etc. can be used. The plasma state can be achieved by, for example, making the inside of the plasma generator a vacuum, and applying the high frequency power source to the
Usually Q. A high frequency of 1 to 2 KW and 13.56 MHz is applied, and the above-mentioned fuso-based hydrocarbon compound is placed under pressure.
Usually o4~G. It can be formed by implanting, radicalizing, and ionizing the material to a pressure of 5 Torr. The fluorine-based polymer film is formed by polymerizing substances in a plasma state such as radicals and ions generated from the fluorine-based hydrocarbon compound, and usually coats the etched cross section of the aluminum-based conductive layer with 10%
It can be formed by adhering to a film thickness of 0 to 1000 people.

In the present invention, the high melting point metal conductive layer is then etched again by reactive ion etching to form metal wiring. In the etching process, etching can be performed in the plasma generating apparatus using the Moeki resist as a mask to form a pattern similar to the etched portion of the aluminum-based conductive layer. For example, Ci2t, BCl2
3, SiCl2. 0, 5F, etc., to increase the etching rate or improve the selective etching property with the underlying silicon. , C.F. This can be carried out by a reactive ion etching method using a gas to which etc. are added. After this etching, it is preferable to form a fluorine-based polymer film on the etched cross section of the high-melting point metal-based conductive layer in the same manner as described above, since this can further improve the corrosion resistance of the metal wiring. CF. removes chlorine-based reaction products adhering to metal wiring forming substrates. , S.F.
Plasma treatment using s or the like may be performed.

(E) Function The fluorine-based polymer film formed on the etched cross section of the aluminum-based conductive layer prevents contact between the aluminum-based conductive layer and moisture.

(f) Example Embodiments of the invention will be described with reference to the drawings.

Implementation - ■ First, as shown in Figure 2, a silicon substrate! A TiW layer 2a having a thickness of 0.3μ is formed on top by sputtering,
On top of this, a film of AISi with a thickness of 0.8 μm was applied by sputtering.
Form layer 3a.

Next, as shown in FIG. 3, a noporac resin 10-quinonediazide compound-based positive photoresist solution is applied onto the AISi layer 3a by spin coating, exposed to light in a predetermined pattern using a reduction projection exposure device, and alkaline A resist layer 4 of a predetermined pattern is developed using a developing solution.
form.

Next, power the plasma generator...! )OO
W, 13. 56Hz1 reactive gas supply rate. ...-B
CIs15Qsc(J,C 12t40SCCMSCH
Fs 2QSCCM, pressure---30taTor
r. Ydc (DC electric field)...--taov, and as shown in FIG. 4, the above-mentioned A
The ISi layer 3a is etched into a predetermined pattern.

Next, in the plasma apparatus, as shown in FIG. 5, the etched cross section of the AISi layer 3 is
00W, 13.56MHz1 reactive gas...
CHF, Reactive gas supply rate...IOOsc
cM, pressure...1O[1aTorr]
A fubuso-based polymer coating 5a having a thickness of 5 GG is formed on the etched cross section of the layer 3.

Next, the plasma device was powered by a power source of 50 QW, 13.56
MHz, reactive gas supply rate...BCQs 6
0SCCM, SF e 603CCM, pressure...
...40a:rorr%Vda...-100
Operating under the condition of V, the TiW layer 2& is etched using the resist layer 4 as a mask as shown in FIG.

Next, as shown in FIG. 7, the etched cross section of this TiW layer 2 is
z; Reactive gas...CHF3, Reactive gas supply rate...IOOsccM; Pressure...l
The TiW layer 2 is treated with a plasma atmosphere generated under conditions of 0OsTorr, and a film thickness of 5.
A fluorine-based polymer coating 5b of 0.00000000000000 is formed, and the resist layer 4 is removed as shown in FIG.
A semiconductor device consisting of a large number of metal wiring lines 6 running in parallel with a line spacing of 0.8 μm was fabricated.

The obtained semiconductor device was left in air at 20°C and 765% mlM for 24 hours with its metal wiring exposed, and then examined under a microscope. There were no signs of corrosion as shown in the comparative example below. It was confirmed that it has excellent corrosion resistance.

Example 2 Implementation IMJ I J Here, between the step of etching the AISi layer 3a and the step of forming a fluorine-based polymer film on the etched cross section of the AISi layer 3, the surface on which the AISi layer 3 is formed is connected to a power supply... ...500W, 13.56MHz,
Reactive gas...CF reactive gas supply rate...
...IOOsccM, pressure...roomT
A semiconductor device was fabricated in the same manner as in Example 1, except that it was subjected to a process of removing deposits adhering to the etched cross section of the AISi layer 3 by treatment with a plasma atmosphere generated under the conditions of .orr.

The metal wiring of the obtained semiconductor device had excellent corrosion resistance as in Example 1.

Example 3 In Example 1, the plasma treatment conditions after etching the TiW layer were changed to CF. A semiconductor device was manufactured using the same method as in Example 1 except for the above.

The metal wiring of the obtained semiconductor device had excellent corrosion resistance as in Example 1.

Comparative example! In Example 3, after etching AISiNA3a into a predetermined pattern, CHF. A semiconductor device was manufactured in the same manner as in Example 3 except that the step of forming a fluorine-based polymer film by plasma treatment using was omitted.

The metal wiring of the obtained semiconductor device was evaluated in the same manner as in Example 1, and 50 granular corrosion marks/cm'' were observed.

(G) Effects of the Invention According to the present invention, there is provided a method for manufacturing a semiconductor device that can suppress corrosion of metal wiring made of an aluminum-based conductive layer stacked on a silicon substrate with a high-melting-point metal-based conductive layer interposed therebetween. I can do something.

By using the manufacturing method of the present invention, it is possible to manufacture a highly reliable semiconductor device with fewer disconnections.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of metal wiring of a semiconductor device manufactured in an example of the present invention, FIGS. 2 to 7 are explanatory diagrams of manufacturing process of metal wiring formed in an example of this invention,
FIG. 8 is an explanatory diagram of deposits generated in the conventional metal wiring manufacturing process, and FIG. 9 is a diagram showing the relationship between etching conditions and the number of occurrences of corrosion in intermediate products in the conventional metal wiring manufacturing process. 5a. 5b... Fluorine polymer coating, 6...
...Metal wiring, 7...Adherence. ! ......Silicon-based temporary, 2.2a...High melting point metal-based conductive layer (TiW layer)
, 3, 3a... Aluminum-based conductive layer (AIS
i layer), 4...Resist layer, 8 11 (A) 8 CB) 8 W (C) Vdc=-260V Vdc=-200V VdC=- 160V vdc (-v)

Claims (1)

[Claims] 1. A resist layer having a predetermined pattern is formed in advance on an aluminum-based conductive layer laminated on a silicon substrate with a high-melting-point metal-based conductive layer interposed therebetween; The aluminum-based conductive layer is etched into a predetermined pattern by reactive ion etching using the layer as a mask, and a fluorinated polymer coating is applied to the etched cross section of the aluminum-based conductive layer by plasma treatment using a fluorinated hydrocarbon compound. 1. A method for manufacturing a semiconductor device, which comprises etching the refractory metal-based conductive layer again using a reactive ion etching method to form a metal wiring.