CN1200456C - Wiring technology of copper doped metal based on A1 material - Google Patents

Abstract

The present invention relates to a technology based on Al metal wiring, which is mainly characterized in that multiple layers of thin films, such as Ta, TaN, Ta, Al, TaN, etc., are continuously deposited in the same equipment by utilizing the method of deposition, wherein Cu and Si atoms are added in Al metal for increasing the electromigration resistance of the Al metal wiring; a compound barrier layer is arranged below an Al layer, and can prevent diffusion in Al and Cu-direction silicon wafers and media; the deposition of the Al metal layer adopts two-step method deposition of a low temperature and a high temperature; an Al seed crystal layer deposited by the low temperature has good compactness; an Al layer deposited by the high temperature has higher hole filling performance and reflow effect; a TaN layer on the Al metal layer can be used as a barrier layer, a top coating layer and a photoetched anti-reflecting layer. The wiring technology based on Al can be suitable for production lines of large-scale integrated circuits of the present Al metal.

Description

Wiring technology of copper doped metal based on the Al material

Technical field

The invention belongs to the large scale integrated circuit manufacturing process technology field, be specifically related to a kind of Al metal line technology.

Background technology

In integrated circuit technology, metal interconnecting wires is owing to provide power supply and the transmission electric signal.The most frequently used conductive metallic material is metal A l and Cu.Al is a kind of favorable conductive metal, resistivity is 2.66 micro-ohm cm, fusing point is 660 ℃, the Al metal forms good Ohmic contact with silicon that mixes or polysilicon easily, the anti-extraneous corrosive power of Al is stronger, adopt ultrasonic method to be in the same place, form integrated circuit finished product with complete function with gold wire bonding.The Al metal is deposited with physical deposition and chemical vapor deposition.Wherein the most frequently used is physical deposition.The Al deposit generally is a method of evaporating in early days, and along with the attenuation of semiconductor integrated circuit metal film thickness, characteristic size is wide constantly dwindles, present most Al deposits have transferred the sputtering method manufacturing to.The CVD deposit of Al also is not very successful, also among the continuation exploitation.

Temperature is closely related mutually with the shallow lake for the character of sputter Al metal film.Under cryogenic conditions, the mobility of Al atom is lower.And under the higher temperature, promptly during temperature T=0.5-0.7Tm, (Tm is the melting temperature of metal, to Al, and Tm=660 ℃), Al can produce diffusion into the surface when deposit.When temperature continued to be increased to T＞0.7Tm, Al can produce the bulk diffusion effect when deposit.During in silicon temperature＞550 ℃, the Al metal can form original position backflow effect, just because of the reflux characteristic of Al, can be used for filling contact hole or through hole, form the Al interconnect posts (Al-plug) of contact hole or filling perforation, simultaneously, backflow can also be eliminated the cavity in the Al metal.In order to reach the backflow effect, particularly allow Al fill the contact hole and the through hole of depth-width ratio＞1, silicon chip must be heated to 550 ℃, and continues about 3 minutes time.Because long pyroprocess, Al must be in the low pressure oxygen-free environment, and is not oxidized in reflux course to guarantee Al.

Al has significant limitation as the metal line material, and wherein, deelectric transferred ability is the main cause that causes circuit reliability.So-called electromigration is meant that the Al ion exists " electron cloud " effect under, move along conducting direction, stay the room, along with the continuous increase in room, can become the cavity in the Al line at last.This cavity finally can cause the open failure of Al line, i.e. electromigration invalidation.In general, electromigratory failure rate sharply increases along with the rising of the current densities of Al lead and working temperature.

The metallization process of early stage middle small scale integrated circuit, the Al metal is to adopt evaporation, electron beam evaporation deposit usually.Arrive large scale integrated circuit, then adopted sputtering method deposit Al.Because sputter has higher deposition rate, can multiple composite material of sputter even high temperature refractory, in addition, before sputter, can carry out sputter process to the surface, remove the natural oxidizing layer on surface, reduce the contact resistance of Al metal.

Along with constantly dwindling of junction depth and constantly reducing of dimension of picture, impel people to consider how further to improve the solution Al metal and the compatibility of shallow junction technology, the filling perforation of Al metal material.

Summary of the invention

The present invention is directed to deficiency of the prior art, propose new Wiring technique in, so that the Al metal has good filling perforation and surface based on the Al material.

The Wiring technique based on the Al material that the present invention proposes is a method of utilizing physical deposition, consecutive deposition Ta, TaN, Ta, Al, TaN plural layers successively in same equipment; And in the Al metal, add Cu and Si atom, with electric conductivity and the high temperature resistant property that improves the Al metallic film, improve the deelectric transferred ability of Al as integrated circuit wiring.

Concrete steps are as follows:

1. first deposit one deck Ta barrier layer;

2. deposit one deck TaN barrier layer on the Ta layer;

3. follow deposit one deck Ta barrier layer;

4. deposit Al layer again, the Al deposit is with the metallic target that contains Cu and Si, and adopts low temperature and the deposit of high temperature two-step method, promptly comprises first deposit ground floor low temperature AI inculating crystal layer, again deposit second layer high temperature Al layer;

5. deposit one deck TaN barrier layer on the Al layer;

6.Al metal reflow.

The Controllable Temperature of physical deposition Ta is made as 400-440 ℃ in the above-mentioned technology, and film thickness is 10nm-30nm.The Controllable Temperature of physical deposition ground floor TaN is made as 400-440 ℃, and film thickness is 30nm-50nmnm.Low-temperature physics deposit ground floor metal A l inculating crystal layer contains Cu, each 0.5-1.5% of Si atom (is radix with Al) among the Al, content is 1-1.4% preferably.Deposition temperature is controlled to be 40-55 ℃, and deposition thickness is 100nm-300nm; High-temperature physics deposit second layer metal Al contains Cu, each 0.5-1.5% of Si atom (is radix with Al) here among the Al, content is 1-1.4% preferably, and the deposition temperature of film is 450 ℃-500 ℃, and deposition thickness is 300nm-500nm.The temperature of physical deposition TaN is 400-440 on Al, and the TaN film thickness is 30nm-50nm.

The present invention is deposit one deck Ta barrier layer at first.Ta is a kind of barrier material of the Cu of preventing diffusion, and Ta has lower resistivity, and during as the ground floor metal, Ta directly contacts with polysilicon gate with the active area of MOS device, forms refractory metal silicide TaSi, reduces the contact resistance of device.Deposit one deck TaN barrier layer on the Ta layer.The main effect of this layer TaN is the diffusion impervious layer as Cu and Al, prevents that Cu and Al from entering in silicon chip and the insulating medium layer.TaN a kind ofly has good barrier effect than Ta or the better barrier material of TiN, the particularly diffusion to Cu and F ion.Follow deposit one deck Ta barrier layer.This layer Ta has lower resistivity, as the substrate of Al low temperature seed crystal deposit, helps Al and forms continuous conducting layers.The Al deposit is with the metallic target that contains Cu and Si, adopts low temperature and the deposit of high temperature two-step method to form.Low temperature deposition Al inculating crystal layer has good compactness, and high temperature Al has higher deposition speed, filling perforation and backflow effect.Concrete technology comprises the low temperature AI inculating crystal layer that first deposit one deck is thin, deposit high temperature Al then.Deposit one deck TaN barrier layer on the Al layer.This layer TaN effect is the diffusion impervious layer as Cu and Al, prevent that Cu and Al from entering in the insulating medium layer, and on the Al film deposit one deck TaN, can improve the electromigration ability of Al metal line, the TaN Al metal of can also drawing up produces hillock when high temperature reflux.Also can be used as the anti-reflecting layer of back step photoetching process, improve pattern integrity and the wide controlling level of bar of photoetching Al.Carry out the Al metal reflow at last, temperature is 500-600 ℃, and time 2-5 minute, vacuum degree was 1-3Torr.

This method selects Ta as the barrier layer.The bottom Ta help reducing contact hole resistance, and rise enhancing and the adhering effect of medium.Deposit TaN diffusion impervious layer on the Ta layer then is the Ta layer.This one deck Ta is beneficial to and forms Al metallic film continuous, homogeneous grain size, also provide additional conductive path for the Al wiring, even in Al metal contact hole or line, the cavity occurred, can not cause electromigration invalidation yet, thereby improve the deelectric transferred ability of Al metal., improve outside the deelectric transferred ability of Al metal on the one hand as barrier material at the TaN at the top of Al, still good Al metal top photoetching anti-reflecting layer helps the hachure exposure and the etching of photoetching intermetallic through-hole interconnection and metal connecting line.

The present invention on the basis of Al basic technology, in the Al metal, add 1% Cu and and 1% Si, to improve the deelectric transferred performance of Al metal line.Low temperature and the deposit of high temperature two-step method are adopted in the Al deposit, and be auxiliary with the high annealing under the vacuum, to improve the filling perforation performance and the surface of Al metal.Al metal and Ta/TaN/Ta barrier layer, bottom and top T aN barrier layer combine, and significantly improve the deelectric transferred ability of Al and the high-temperature stability of Al metal film, have improved the reliability of integrated circuit.

Description of drawings

Fig. 1 represents the metal interconnected technology profile based on the Al material.

Illustration: 1---Ta; 2---TaN; 3---Ta; 4---Al (1%Cu); 5---TaN;

Embodiment

Further specifically describe the present invention below by embodiment, embodiment:

1, this programme can be finished the plural layers deposit on a multi-cavity chamber physical vapor deposition (PVD) equipment (for example ENDURA 5500 PVD equipment of company of Applied Materials production).

2, at first carry out degasification (temperature is 400 ℃-500 ℃, 120 seconds-180 seconds time);

3, adopt the Ar plasma that preliminary treatment is carried out on the surface subsequently, time 10-20 second, remove the remaining goods and materials of layer insulation dielectric surface;

4, and then deposit layer of metal Ta, thickness is 20nm, temperature is 420 ℃;

5 and then deposit TaN, thickness 40nm, deposition temperature are 420 ℃;

6, deposit one deck Ta on TaN, thickness is 20nm, temperature is 420 ℃.

7, deposit contains the Al metal film of 1%Cu and 1%Si, is divided into for 2 steps:

The first step: under low temperature (50 ℃) condition, the Al of deposit 100nm-300nm (contains 1%Cu, 1%Si) inculating crystal layer;

Second step: under high temperature (450 ℃-500 ℃), deposition thickness is that the Al of 300nm-500nm (contains 1%Cu, 1%Si) film;

8, deposit one deck TaN again on the Al film, thickness is 40nm;

9, Al metal reflow, temperature are 550 ℃, 3 minutes time.So far, finish based on the basic step of mixing the metal interconnected technology of copper of Al material, its generalized section as shown in Figure 1.

10, after the multiple layer metal deposit is finished, can send into photo-mask process, carry out gluing, exposure, development, reactive ion etching etching and the operation of removing photoresist, prepare the metal superfine lines that are used for the integrated circuit multilayer interconnection.

Claims (6)

1, a kind of Wiring technique based on the Al metal is characterized in that utilizing the method for physical deposition, consecutive deposition Ta, TaN, Ta, Al, TaN plural layers successively in same equipment, and concrete steps are:

(1) deposit one deck Ta barrier layer at first;

(2) deposit one deck TaN barrier layer on the Ta layer;

(3) follow deposit one deck Ta barrier layer;

(4) deposit Al layer again, Al deposit are with the metallic target that contains Cu and Si, adopt low temperature and the deposit of high temperature two-step method;

(5) deposit one deck TaN barrier layer on the Al layer;

(6) Al metal reflow.

2, according to the described Wiring technique based on the Al metal of claim 1, the temperature that it is characterized in that physical deposition Ta is 400-440 ℃, and film thickness is 10nm-30nm.

3, the Wiring technique based on the Al metal according to claim 1, the temperature that it is characterized in that physical deposition ground floor TaN is 400-440 ℃, the TaN film thickness is 30nm-50nm.

It is 4, according to claim 1 that (Wiring technique of metal is characterized in that low-temperature physics deposit ground floor metal A l inculating crystal layer, contains Cu, each 0.5-1.5% of Si atom among the Al, and deposition temperature is 40-55 ℃, and deposition thickness is 100nm-300nm based on Al.

5, the Wiring technique based on the Al metal according to claim 1 is characterized in that high-temperature physics deposit second layer metal Al, contains Cu, each 0.5-1.5% of Si atom among the Al, and deposition temperature is 450 ℃-500 ℃, and deposition thickness is 300nm-500nm.

6, the Wiring technique based on the Al metal according to claim 1 is characterized in that: the temperature of physical deposition TaN is 400-440 ℃ on Al, and the TaN film thickness is 30nm-50nm.

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