KR20070027268A - Method for preventing copper diffusion on process for forming pad in copper metal line semiconductor device - Google Patents

Abstract

A method is provided to prevent the diffusion of a copper component in a pad forming process of a copper line semiconductor device by changing characteristics of TiSiN using an SiH4 concentration reducing process. A copper line layer is formed on a semiconductor substrate. A passivation layer is formed on the entire surface of the copper line layer. The copper line layer is selectively exposed to the outside by patterning the passivation layer. A barrier metal is formed on the exposed copper line layer. A metal film for wire-bonding is formed on the barrier metal. The barrier metal is obtained by depositing a TiN layer on the exposed copper metal layer and soaking properly SiH4 into the TiN layer without a semi-pump process.

Description

METHOD FOR PREVENTING COPPER DIFFUSION ON PROCESS FOR FORMING PAD IN COPPER METAL LINE SEMICONDUCTOR DEVICE}

1 is a cross-sectional view of a copper wiring and pad forming process of a conventional semiconductor device;

2 is a cross-sectional view illustrating a diffusion concept of a copper component in a conventional copper wiring and pad forming process;

3 is a plan view and an electron microscope image of the aluminum pad metal layer of the conventional 0.13um FCT,

4 is an exemplary AES analysis result for the discolored portion of the aluminum pad metal layer shown in FIG.

5A to 5C are cross-sectional views of a copper wiring and pad forming process of a semiconductor device according to the present invention;

6 is an exemplary view illustrating a barrier metal forming process condition for preventing copper diffusion according to a first embodiment of the present invention;

7 is a plan view of the aluminum pad metal layer according to the conditions of FIG.

8 is a cross-sectional view of the aluminum pad metal layer to which each split condition of FIG. 6 is applied;

9 is a view illustrating a barrier metal forming process condition for preventing copper diffusion according to a second embodiment of the present invention;

10 is a plan view of the aluminum pad metal layer according to the conditions of FIG.

11 is a cross-sectional view of the aluminum pad metal layer according to the conditions of FIG. 9.

<Brief description of the major symbols in the drawings>

200: top via 202: top copper wiring layer

204: barrier metal layer 206: aluminum pad metal layer

208: void 210: copper diffusion unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing process. In particular, the pad formation of a copper wiring semiconductor device prevents copper (Cu) wiring from diffusing to a pad portion through a barrier metal during wire bonding of the semiconductor device. It relates to a copper diffusion preventing method during the process.

In recent years, as the size of semiconductor devices decreases, the contact size for coupling between metal interconnections of semiconductors continues to decrease for high integration and high capacity, and according to the high aspect ratio of contact holes due to the reduction in size, conventional aluminum and tungsten In the case of forming the metal wires, there is a problem that a problem of time delay due to low embedding characteristics and high resistance of aluminum and tungsten occurs.

Accordingly, copper thin films having low specific resistance and excellent electromigration (EM) have been widely studied as a promising electric wiring material of ultra-high integrated circuit ULSI.

However, there are several issues to be solved in using copper as the metal wiring material, one of which is to find a diffusion barrier that can effectively prevent the diffusion of copper into silicon or oxide film. This is because copper has a very fast diffusion rate into the silicon and the oxide film, which causes problems such as shallow junctions and breakage due to diffusion of copper.

To this end, conventionally, TiN, TiW, TaN, and WN deposited by a sputtering method with a copper diffusion barrier have been studied, but such thin films have poor step coverage due to continuous integration of semiconductor devices and conformality. There were problems such as poor conformality.

In order to solve these problems, it has excellent step coverage and conformality compared to TiN, TaN, etc., and serves as a diffusion barrier with a small thickness, and a large amount of particles due to the thick thickness such as TiN, TaN, etc. TiSiN deposited by chemical vapor deposition has been studied to solve problems such as particle generation and low throughput.

FIG. 1 illustrates a process for forming a copper wiring and a pad of a conventional semiconductor device. In the semiconductor device using copper as a metal wiring, as shown in FIG. 1, a top metal copper wiring (Cu) is shown. After pad opening is performed on the pad 100 to form a pad, a pad barrier metal layer (TiSiN) 102 is formed and a pad metal (Al) 104 is deposited. Subsequently, a metal for wire bonding is deposited on the pad open region 106.

However, as shown in FIG. 2, which illustrates the concept of diffusion of copper components in the conventional copper wiring and pad forming process as described above, a via hole having a different size of the top via 200 is usually different. More stress on and below the barrier metal than on other layers because the pattern density of the larger and top metal (Cu) 202 is lower compared to other layers. Cause. For this reason, TiSiN, the barrier metal 204 between the top metal layer 202 and the aluminum pad metal layer 206, has poor step coverage and conformality. Has

Moreover, the TV sinter process exerts thermal stress on the barrier metal 204 so that the copper wiring layer (Cu) 202 under the barrier metal 204 easily penetrates the weak barrier metal TiSiN and the aluminum pad metal layer (Al metal). A diffusion 210 is generated in the pad 206, and a void 208 is generated in a portion of the top metal 202 in which the copper component Cu has escaped. In addition, the copper component diffused into the pad metal layer 206 has a problem of generating a bondability problem during wire bonding of the package.

3 is a top view and an electron microscope (SEM) image of an aluminum pad metal layer (Al metal pad) of the conventional 0.13μm foundry compatible technology (FCT), in the plan view shown in (a) of FIG. As shown in FIG. 3 (b), the electron microscope image shown in FIG. 3 (b) shows that an abnormal substance is found in all the rough metal pad Al metal pads of the 0.13 μm Dual Damascene technology. As can be seen, the copper component is diffused from the uppermost copper wiring layer to the aluminum pad metal layer. As a result, it can be seen that vacancy has occurred in the copper wiring layer.

FIG. 4 is an exemplary AES analysis result of the discolored portion of the aluminum pad metal layer shown in FIG. 3, and a copper atomic map for the electron microscope image shown in FIG. As shown in (b) and (c) of FIG. 4, which is an example of AES electron spectrum, it can be seen that the abnormal material of the aluminum pad metal layer is a copper component.

Accordingly, an object of the present invention is to provide a method for preventing copper diffusion in a pad forming process of a copper wiring semiconductor device capable of preventing diffusion of copper wiring to a pad portion through a barrier metal during wire bonding of the semiconductor device.

The present invention for achieving the above object is a method for preventing copper diffusion during the pad formation process of a copper wiring semiconductor device, (a) forming a copper wiring layer, (b) forming a passivation film on the entire upper surface of the copper wiring layer And (c) etching the copper passivation by patterning the passivation film, (d) forming a thin film of the barrier metal layer on the copper wiring exposed under the patterned passivation film, and (e) the barrier Forming a metal layer for wire bonding on the metal layer, wherein the barrier metal layer is formed of a TiSiN film having a thickness of 100 Å, before SiH4 soak on TiN, and removing particles according to the TiN formation. By eliminating the semi-pump process, the concentration of SiH 4 to TiN in the composition ratio of the TiSiN film is reduced.

Hereinafter, with reference to the accompanying drawings will be described in detail the operation of the preferred embodiment according to the present invention.

5A through 5C are cross-sectional views illustrating a pad forming process for preventing copper diffusion through a barrier metal in a copper wiring semiconductor device according to an exemplary embodiment of the present invention. Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 5A to 5C.

First, as shown in FIG. 5A, a copper wiring layer 502 is formed in a wiring region on a semiconductor substrate 500, and then a passivation film 504 is deposited. The passivation film is then patterned through a photolithography process to form a first pad open 506.

Next, as shown in FIG. 5B, a barrier metal 508 is deposited on the copper wiring layer 502 of the first pad open area to prevent diffusion of copper components. The barrier metal 508 uses TiSiN formed by depositing TiN (titanium nitride) on the copper wiring layer 502 and then absorbing SiH 4 onto the TiN layer.

Thereafter, as shown in FIG. 5C, an aluminum pad metal layer 510 is formed on the barrier metal layer 508 for wire bonding, and then a passivation film 512 is applied on the aluminum pad metal layer 510. Patterning is performed through a photolithography process to form a second pad open 514 for wire bonding.

FIG. 6 illustrates a barrier metal forming process condition for preventing copper diffusion according to a first embodiment of the present invention, and FIG. 7 illustrates a plan view of an aluminum pad metal layer according to each condition of FIG. 6.

Hereinafter, the copper diffusion prevention according to the barrier metal forming conditions will be described with reference to FIGS. 6 and 7.

First, condition 1 is a general barrier metal forming condition (POR), wherein TiSiN is formed by pyrolysis of Tetrakis-Dimethyl-Amino-Titanium (TDMAT) at a substrate temperature of generally 350 ° C. TiN deposition is also carried out by H + / N + plasma treatment, and this series of steps is repeated until the desired thickness is formed. Then, TiN is exposed in-situ to silane (SiH 4) to form TiSiN, and the desired 100 μs TiSiN may be obtained by repeating two processes as shown in [Formula 1] below.

Ti [N (CH3) 2] 4 → TiN (C) + HN (CH3) 2 + H2N (CH3) + Hydrocarbons

TiN (C) + SiH4 → TiSiN

However, condition 1 of FIG. 6 can confirm discoloration due to copper component diffusion on the surface of the aluminum pad metal layer, as shown in FIG.

Conditions 2 and 3 are to find a better condition in a conventional barrier metal process, and condition 2 is a case where the thickness of TiSiN currently deposited at 100 GPa is increased to 300 GPa, and (b) of FIG. It can be seen that the copper component diffusion does not occur as shown in FIG.

Next, condition 3 increases the SiH4 soak time of 10 sec to 30 sec, considering that SiH4, which determines the film quality and thickness of the barrier metal TiSiN, is determined by the soak time. In this case, it can be seen that copper component diffusion occurs as shown in FIG.

Conditions 4, 5, and 6 are intended to explore the potential for new barrier metals. TaN / Ta is a commercially widely used barrier metal and a TiSiN / TiN / Al / Ti / TiN complex barrier metal. metal) is a barrier metal generally used in an aluminum (Al) process. In the case of such a new barrier metal, it can be seen that copper diffusion did not occur as shown in (d), (e), and (f) of FIG. 7.

8 is a cross-sectional view of the aluminum pad metal layer after all the processes are applied by applying the respective split conditions of FIG. 6. Referring to FIG. 8, FIG. 8B is a cross-sectional view of an aluminum pad metal layer in which copper diffusion does not occur under conditions 2, 4, 5, and 6 in which diffusion of copper does not occur in FIG. 7. ), (d), (e) and (f).

FIG. 9 illustrates a barrier metal forming process condition for preventing copper diffusion according to a second embodiment of the present invention, and FIG. 10 illustrates a plan view of an aluminum pad metal layer according to each condition of FIG. 9.

Hereinafter, with reference to FIGS. 9 and 10, the copper diffusion prevention according to the barrier metal forming conditions will be described.

9 and 10, as shown in plan views of the aluminum pad metal layers illustrated in FIGS. 10B and 10D, copper component diffusion does not occur under conditions 2 and 4 of FIG. 9. As shown in the plan views of the aluminum pad metal layers shown in FIGS. 10A and 10C, it can be seen that the copper component diffusion occurs under the conditions 1 and 3 of FIG. 9.

FIG. 11 is a cross-sectional view of the aluminum pad metal layer under the corresponding conditions corresponding to the plan view of the aluminum pad metal layer according to the respective conditions of FIG. 10, wherein the copper component diffusion did not occur under the conditions 2 and 4 of FIG. 9. It can be seen through (b) and (d) of FIG.

On the other hand, in the first embodiment of the present invention as described above it was not possible to prevent the copper diffusion (Cu diffusion) by increasing the SiH4 absorption time (soak time). Therefore, in the second embodiment of the present invention, the SiH4 was indirectly controlled by skipping a semi-pump step before generating SiH4. The semi-pump step is a step of pumping before SiH4 soak and removing particles generated while forming TiN. In the second embodiment of the present invention, the semi-pump step is omitted. As a result, the concentration of SiH 4 compared to TiN was reduced in the composition ratio of TiSiN. For this reason, the diffusion of a copper component was prevented by changing the property of TiSiN.

As described above, in the present invention, when the wire bonding in the semiconductor device of the copper wiring, the copper component of the top layer copper wiring is abnormally diffused to the aluminum pad metal layer through the barrier metal which is structurally weak, thereby causing a bondability problem during wire bonding of the package. It is a process to remove particles generated while forming TiN by pumping before SiH4 (silane) soak when forming barrier metal to prevent diffusion of copper components. By skipping the pump (semi-pump) process, the concentration of SiH4 to TiN in the TiSiN composition ratio is reduced to change the properties of TiSiN to prevent the diffusion of copper components.

Meanwhile, in the above description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the invention should be determined by the claims rather than by the described embodiments.

As described above, in the present invention, when the wire bonding in the semiconductor device of the copper wiring, the copper component of the uppermost copper wiring is abnormally diffused to the aluminum pad metal layer through the barrier metal that is structurally fragile, so that the bondability problem during the wire bonding of the package. In order to prevent the formation of a metal oxide, a process of pumping before SiH4 (silane) soak during barrier metal formation to prevent diffusion of copper components to remove particles generated while forming TiN. By skipping the phosphorus semi-pump process, there is an advantage to prevent the diffusion of copper components by changing the properties of TiSiN by reducing the concentration of SiH4 to TiN in the composition ratio of TiSiN.

Claims (5)

As a method for preventing copper diffusion in a pad forming process of a copper wiring semiconductor device, (a) forming a copper wiring layer on the semiconductor substrate, (b) forming a passivation film on the entire upper surface of the copper wiring layer; (c) etching the passivation film to expose copper wiring; (d) forming a barrier metal layer on the copper wiring exposed under the patterned passivation film; (e) forming a metal layer for wire bonding on the barrier metal layer Copper diffusion prevention method during the pad formation process of a copper wiring semiconductor device comprising a. The method of claim 1, In the step (d), (d1) depositing TiN on the exposed copper wiring layer; (d2) soaking SiH 4 on the TiN layer to form TiSiN, a barrier metal; Copper diffusion preventing method during the pad formation process of a copper wiring semiconductor device comprising a. The method of claim 2, In the step (d2), the barrier metal layer, a copper diffusion preventing method in the pad formation process of a copper wiring semiconductor device, characterized in that formed of a 100 Å thick TiSiN film. The method of claim 2, In the step (d2), the concentration of SiH4 compared to TiN in the composition ratio of the TiSiN film is omitted by a semi-pump process, which is a particle removal process generated when the TiN is formed, before the SiH4 is absorbed on the TiN. The copper diffusion preventing method of the pad forming process of the copper wiring semiconductor device, characterized in that formed to be reduced. The method of claim 1, In the step (e), the metal layer for wire bonding, copper diffusion prevention method in the pad formation process of a copper wiring semiconductor device, characterized in that the aluminum containing copper in a predetermined ratio.

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