CN1115723C - Tungsten nitride (WNx) layer manufacturing method and metal wiring manufacturing method using the same - Google Patents

Abstract

A new method of fabricating a selective tungsten nitride layer and a method of fabricating metal interconnections using the same method are provided. In these methods, a tungsten nitride layer is selectively deposited only in a contact hole by adjusting the flow rate ratio of injected nitrogen-containing gas and tungsten source gas. Thus, erosion on the silicon substrate is prevented and a tungsten nitride layer stable at high temperatures is produced. In addition, the contact resistance of the metal wiring can be reduced.

Description

Method for manufacturing tungsten nitride layer and method for manufacturing metal wiring using the same principle

The present invention relates to a method of producing semiconductor devices, in particular, to a method of producing a tungsten nitride (WN _x ) layer which can be selectively formed in a contact hole or without intruding into the substrate. It is formed on or over the underlying metal wiring layer and is stable at high temperatures. The invention also relates to a method for producing metal interconnections in the same way.

As the integration level of semiconductor integrated circuits (ICs) increases, the width of metal interconnection lines decreases, while the aspect ratio of contact holes continues to increase. However, aluminum (Al) alloy thin films currently used as metal wiring materials show poor step coverage in contact holes, or void spots due to plating. As a result, short circuits occur between interconnect lines, reducing the reliability of integrated circuits. Therefore, selective chemical vapor deposition-tungsten (SCVD-W) has been attracting people's efforts to use tungsten (W) as a material for metal wiring through chemical vapor deposition (CVD).

1A to 1E show a method of forming a tungsten layer by chemical vapor deposition.

In FIG. 1A, impurity regions 12 for defining source/drain regions are formed by implanting ions into a silicon substrate 10. In FIG. Then, a silicon oxide layer is formed as insulating layer 13 on the entire surface of substrate 10 including impurity region 12 to a thickness of 500-2000 angstroms. As shown in FIG. 1B , the trench 19 for making metal wiring is formed by etching the insulating layer 13 and the silicon substrate 10 to a predetermined depth.

Subsequently, a titanium (Ti) layer is deposited to a thickness of 200-1500 angstroms on the insulating layer 13 and in the trench 19, and heat-treated. As a result of the heat treatment, the silicon substrate 10 reacts with the Ti layer, thus forming a titanium silicide (TiSix) layer 14 as the only resistive layer on the surface contacting the substrate. The remaining titanium that did not react with the substrate was then removed by wet etching to obtain the result shown in Figure 1C.

After this, as shown in FIG. 1D, a titanium nitride (TiN) layer is deposited as a diffusion barrier layer 15 to a thickness of 150-900 Angstroms, and a tungsten layer 16 is deposited on the diffusion barrier layer 15 to a thickness of 1000 angstroms or more.

Then, the resulting product is etched and reduced by chemical mechanical polishing (CMP), and as shown in FIG. 1E , the tungsten layer 16 remains only in the trench 19, which makes the metal connection.

However, as mentioned above, when the metal wiring is fabricated by selective chemical vapor deposition-tungsten (SCVD-W), the TiN layer has some physical characteristics, such as tension, different from those used as the metal wiring layer as a diffusion barrier. The W layer, and the contact surface between the two layers is strongly stressed. Therefore, the W layer will be lifted, especially the TiN layer/W layer may be lifted from the insulating layer when the chemical mechanical polishing process requires an external mechanical force.

On the other hand, when the impurity region is made of P ⁺ impurity boron (B), the impurity reacts with Ti to generate TiB ₂ in the subsequent heating process. As a result, the resistive contact characteristic decreases while the contact resistance increases.

In order to overcome the above problems, a method as shown in FIG. 2A has been proposed, wherein the tungsten layer 24 is made into a resistance layer, and the tungsten nitride layer 25 is made on the silicon substrate 20 as a diffusion barrier layer on the impurity domain 22, and then A tungsten layer 26 is formed as a metal wiring layer.

In the above method, the tungsten layer 24 is used as a resistive layer by flowing tungsten fluoride (WF ₆ ) at 6 sccm and hydrogen (H ₂ ) at 200 sccm respectively, at a deposition temperature of 600° C. and at an atmospheric pressure of 0.1 Torr to produce a thickness of 200 Å. -1500 Angstroms. Then, a tungsten nitride layer 25 is deposited to a thickness of 150-900 angstroms as a diffusion barrier layer, and a tungsten layer 26 is deposited on the tungsten nitride layer 25 to a thickness of 1000 angstroms or more. The resulting product is etched back, which makes a metal connection. A cross-section of the metal connection is shown in the scanning electron micrograph (SEM) of Figure 2B.

The tungsten layer made into the resistance layer shows excellent adhesion to silicon, but on the other hand, the reduction reaction between tungsten and silicon when forming tungsten silicide leads to erosion of the silicon substrate, which damages the electrical characteristics, as shown in Figure 2B shown. In the VLSI era, where junction depths have dropped to 0.1um or below, erosion has become a more serious problem. Further, since tungsten reacts with silicon at a temperature of 550° C. or above, subsequent processing must be performed at a temperature higher than 550° C., and it is difficult to apply the above metal wiring manufacturing method to a semiconductor device manufacturing process.

SUMMARY OF THE INVENTION To overcome the above-mentioned problems, an object of the present invention is to provide a method of manufacturing a semiconductor device.

In order to achieve the above object, a method for manufacturing a tungsten nitride layer of a semiconductor device is provided, comprising the following steps: <a> forming an insulating layer on a semiconductor substrate on which a conductive layer is formed; <b> forming a contact by etching the insulating layer and <c> forming a titanium silicide resistive layer in the contact hole; and <d> controlling the nitrogen-containing gas and the tungsten source by selectively reacting the nitrogen-containing gas, the tungsten source gas, and the reducing agent gas The flow rate of the gas is such that the flow rate of the nitrogen-containing gas is 2 to 7 times that of the tungsten source gas, and the tungsten nitride layer is selectively deposited on the resistance layer in the contact hole and the sidewall of the contact hole, thereby controlling the tungsten nitride layer formation location and prevent the formation of a tungsten nitride layer on the insulating layer outside the contact hole.

In order to achieve the above object, there is also provided a method for manufacturing metal wiring of a semiconductor device, comprising the following steps: <a> forming an insulating layer on a semiconductor substrate on which a conductive layer is formed; <b> forming a contact by etching the insulating layer holes to expose the conductive layer; and <c> fabricate a tungsten silicide resistance layer on the conductive layer exposed through the contact hole; <d> control the The flow rate of the nitrogen-containing gas and the tungsten source gas is such that the flow rate of the nitrogen-containing gas is 2 to 7 times the flow rate of the tungsten source gas, and a tungsten nitride layer is selectively deposited on the resistance layer in the contact hole and on the sidewall of the contact hole, Thereby controlling the formation position of the tungsten nitride layer and preventing the formation of the tungsten nitride layer on the insulating layer outside the contact hole; and <e> forming a metal layer on the tungsten nitride layer.

In the present invention, it is preferable to use one of WF ₆ and WCl ₆ as the tungsten source gas; one of N ₂ , NH ₃ and methyl hydrazine as the nitrogen-containing gas; and H ₂ , SiH ₄ , one of SiH ₁ Cl ₃ and PH ₃ is used as the reducing agent gas.

The flow ratio of nitrogen-containing gas to tungsten source gas can be 0.5-100, preferably 2-7. The flow ratio of reducing agent gas to tungsten source gas can be 0-500, preferably 20-50.

Preferably, several steps are included in the step of making the resistance layer: depositing a tungsten nitride layer on the conductive layer exposed by the contact hole; heat-treating the resulting product with the tungsten nitride layer to A resistive layer is made of a thin tungsten silicide layer so that the tungsten on top of the tungsten nitride layer reacts with the silicon substrate.

According to the present invention, the tungsten nitride layer is selectively formed in the contact hole exposing the silicon substrate or the underlying metal wiring layer, thus making highly reliable metal wiring.

Above-mentioned purpose and advantage of the present invention will become clearer by detailed description to preferred embodiment and with reference to accompanying drawing:

1A to 1E are cross-sectional views explaining a conventional method of manufacturing a metal wiring of a Ti/TiN/W structure;

FIG. 2A is a cross-sectional view explaining a conventional method of manufacturing a metal interconnect of a W/WN _x /W structure;

Fig. 2B is a scanning electron micrograph (SEM) photo of the cross-section of the metal wiring shown in Fig. 2A;

Figure 3 is a cross-sectional view of a process chamber for depositing a _WNx layer according to the present invention;

4A to 4D are scanning electron micrographs showing cross-sections of TiN layers selectively grown according to _NH3 gas flow;

Figure 5 is a graph showing the X-ray diffraction results of a WN layer made in accordance with the present invention;

6A to 6D are cross-sectional views explaining a method for manufacturing a metal wiring of a semiconductor device according to a first embodiment of the present invention;

7A and 7B are cross-sectional views explaining a method for manufacturing a metal wiring of a semiconductor device according to a second embodiment of the present invention;

8A to 8E are cross-sectional views of a method for manufacturing metal interconnections of a semiconductor device according to a third embodiment of the present invention.

WN _x layer growth equipment

Figure 3 is a cross-sectional view of a chemical vapor deposition process chamber for depositing a _WNx layer in accordance with the present invention.

Referring to FIG. 3, a susceptor 30 for loading a wafer thereon is installed in the lower part of the processing chamber 40, and an infrared (IR) lamp 39 is installed in the upper part for heating the temperature of the wafer 32 to a suitable reaction temperature. temperature. The tungsten source gas and the nitrogen-containing gas are injected from the first gas inlet 34 and flow horizontally onto the wafer 32 mounted on the susceptor 30 . The reducing agent gas is injected from the second gas inlet 36, flows vertically onto the wafer 32 through a mesh nozzle 38, and reacts with the gas introduced from the first gas inlet 34, thus forming a WN _x layer on the wafer 32. After the reaction, the gas is evacuated through an outlet 42 opposite the first and second gas inlets 34 and 36 .

Fabrication of the WN layer

Potential sources of contamination in process chamber 40 are minimized by placing the process chamber at an approximate vacuum of ^10-6 Torr or below. Then, the susceptor 30 is loaded with a silicon substrate having impurity regions formed thereon; A pure metal of one of cobalt (Co), titanium (Ti), copper (Cu) and platinum (Pt), or an underlying metal wiring layer made of one of their silicon compounds, or one of their alloys. The processing chamber 40 is heated to 200-700° C. by the IR lamp 39, and then reactant gases are introduced from the first and second gas inlets 34 and 36, preferably at a pressure of 0.01-1 Torr. Here, it is preferable to use WF ₆ or WCl ₆ as the tungsten source gas, and methyl hydrazine, N ₂ or NH ₃ as the nitrogen-containing gas, which are injected from the first gas inlet 34 . One of H ₂ , SiH ₄ , SiH ₁ Cl ₃ , SiH ₂ Cl ₂ and PH ₃ is preferably used as the reducing agent gas, which is injected from the second gas inlet 36 . The flow ratio of nitrogen-containing gas to tungsten source gas is preferably 0.5-100, most preferably 2-7. The flow ratio of the reducing agent gas to the tungsten source gas is preferably 0-500, most preferably 20-50.

Figures 4A to 4D are scanning electron micrographs showing the growth of _WNx layers according to the flow ratio of _NH3 gas to tungsten source gas.

_After a silicon substrate with a contact hole inside is loaded into the chemical vapor deposition process chamber 40 of _FIG . The deposition temperature is 600° C., the flow rate of WF ₆ is 6 sccm, and the flow rate of H ₂ is 200 sccm under the pressure of 0.1 Torr. The results obtained are shown in the scanning electron micrographs of Figures 4A to 4D.

From Figure 4A, it is shown that only the pure tungsten layer was formed in the contact hole, indicating that the tungsten layer severely erodes the substrate, which was a problem in the previous process. On the other hand, with the flow rate of _NH3 being 10 sccm, the erosion was suppressed as shown in Fig. 4B, but the film hardly grew and a central nucleus was generated only on the bottom surface of the contact hole. With the NH ₃ flow rate of 20 sccm, as shown in FIG. 4C , a WN _x layer was selectively formed only on the substrate portion and the sidewall of the contact hole, not on the silicon oxide layer. However, as shown in FIG. 4D, with the flow rate of _NH3 being 40 sccm, the selective deposition characteristic of the _WNx layer disappeared and it was formed over the entire substrate surface.

Therefore, it was concluded that by adjusting the flow ratio of the nitrogen-containing gas to the tungsten source gas, the _WNx layer could be selectively grown only in the contact holes. This is more evident in the X-ray diffraction results of WN _x of Fig. 4C shown in Fig. 5. In Fig. 5, three peaks of the β-W ₂ N phase and different crystallographic orientations are shown, which indicate that the WN _x layer is selectively grown on the silicon substrate.

Method of making metal connection

Referring to FIGS. 6A to 8E , a method of manufacturing metal wiring of a semiconductor device using the above-described WN _x layer manufacturing method will be described.

first embodiment

Referring to FIG. 6A, an insulating layer 103, such as a silicon oxide layer, is formed to a thickness of 500-2000 angstroms on a silicon substrate 100 with impurity regions 102 therein. Here, the silicon oxide layer as the insulating layer 103 may be replaced by a silicon nitride layer, or by a coating obtained by implanting impurities into a silicon oxide layer or a silicon nitride layer. Then, the insulating layer 103 is dry-etched by photolithography to form a contact hole 110 for exposing the impurity region 102 .

Referring to FIG. 6B, a Ti layer is deposited on the insulating layer 103 and in the contact hole 110 to a thickness of 200-1500 angstroms. The resulting resultant is then heat-treated so that the Ti layer reacts with the silicon substrate 100 exposed by the contact hole 110, so that a TiSix layer 104 is formed only on the contact surface of the contact hole 110 and the silicon substrate 100. The remaining Ti that has not reacted with the substrate is removed by wet etching. The TiSix layer 104 acts as a resistive layer.

Referring to FIG. 6C , the silicon substrate 100 is heated to 200-700° C., by flowing nitrogen-containing gas, tungsten source gas and reducing agent gas onto the silicon substrate 100 , on the substrate 100 exposed by the contact hole 110 and the insulating A layer of WN _x is selectively deposited on the sidewalls of layer 103 . Here, the flow ratio of the nitrogen group gas to the tungsten source gas is 0.5-100, and the flow ratio of the reducing agent gas to the tungsten source gas is 0-500.

Referring to FIG. 6D , after the WN layer 105 is formed, only a thin metal layer 108 is deposited in-situ in the contact hole 100 to form a metal connection. Here, the metal layer is preferably made of a pure metal such as one of Al, W, Mo, Co, Ti, Cu and Pt, or one of their silicon compounds, or one of their alloys.

second embodiment

The difference between the second embodiment and the first embodiment is that a groove 109 is made by etching the insulating layer 103 and the substrate 100, and then a metal wiring layer is made as shown in FIG. 7A instead of the one shown in FIG. 6A. A metal line is formed in the contact hole 110 made only by etching an insulating layer. In Fig. 7 B, after trench 109 is formed, TiSix layer 104 as resistance layer, _WNx layer 105 as diffusion barrier layer and tungsten layer 108 as metal layer are made successively, and this is just like the mode of the first embodiment A metal connection is also completed. The reason for making the trench 109 is to overcome the problem of increasing the aspect ratio of the contact hole.

third embodiment

The third embodiment is very different from the first and second embodiments in that the TiSix layer is not used as the resistance layer, but by chemical vapor deposition, depositing tungsten or tungsten compounds such as tungsten silicide to reduce the contact resistance, and By chemical vapor deposition, a WN layer is deposited in situ as a diffusion barrier.

Referring to FIG. 8A, a device isolation region 101 is formed on a silicon substrate 100 according to a common device isolation method to separate active regions, and then an impurity region, such as an N ⁺ or P ⁺ junction 102, is formed in a The active region is made by ion implantation. Next, an insulating layer 103, such as BPSG, is plated on the resultant resultant to planarize the execution step.

Referring to FIG. 8B , the insulating layer 103 is etched by photolithography, and a contact hole 110 is formed to expose the impurity region 102 of the silicon substrate 100 .

Referring to FIG. 8C, on the resultant result including the contact hole 110, a resistive layer 124 containing tungsten is formed by chemical vapor deposition. Here, the resistance layer 124 can be made in the following 4 ways:

<1>The tungsten source gas flows into the tungsten source gas in a short enough time without causing corrosion on the silicon, so as to deposit the tungsten resistance layer 124;

<2>In the initialization deposition, the tungsten nitride resistance layer 124 is made very thin, by setting the flow rate ratio of nitrogen-containing gas and tungsten source gas to 2 or below, a large amount of tungsten is only at the bottom of the contact hole, which just Erosion on the silicon is prevented. Then, by increasing the flow rate of the nitrogen-containing gas so that the flow rate ratio of the nitrogen group gas to the tungsten source gas reaches 2-100, preferably 2-7, a _WNx layer 125 is formed in the contact hole. In this way, erosion on the silicon can be prevented and the WN layer can be selectively grown only in the contact holes;

<3>SiH ₄ or SiH ₂ Cl ₂ is mixed with tungsten source gas to make resistance layer 124, and the mixed gas is deposited at 500°C or above, which makes tungsten silicide; or

<4> The barrier metal of the WN _x layer is directly deposited on the silicon substrate and calcined, so that the tungsten on the WN layer reacts with the underlying silicon to form tungsten silicide as the resistance layer 124 .

Referring to FIG. 8D, a diffusion barrier layer 125, that is, the WN layer, is deposited to a thickness of 500 angstroms or more in the same chamber in which the resistive layer 124 is deposited in the same manner as in the first embodiment.

Referring to FIG. 8E, a metal wiring layer 128 is deposited on the resultant resultant on which the diffusion barrier layer 125 is formed. Metal layer 128 is preferably formed by depositing a wiring metal such as Al or Cu.

Therefore, as described above, according to the present invention, a _WNx layer can be selectively formed only on the sidewall of the contact hole and on the silicon substrate or the underlying metal wiring layer exposed by the contact hole, not on the insulating layer. superior. In this way, since the W layer as the metal wiring layer is made after the WN _x layer as the diffusion barrier layer is formed, the tungsten nitride and tungsten layers have similar physical properties, and the improvement produced by the conventional metal wiring layer can be eliminated. prevent. When the resistive layer is made according to the third embodiment of the present invention, the corrosion of the substrate is overcome and the subsequent high temperature treatment can make a stable semiconductor device. In addition, it is possible to prevent the contact resistance from being increased due to the use of the Ti layer as the resistance layer.

The present invention is not limited to the above-mentioned embodiments, and it is easy to understand that any expert in the field can obtain various modifications within the spirit and scope of the present invention.

Claims (19)

1. method of making the semiconductor device tungsten nitride layer may further comprise the steps:

＜a〉make in the above on the Semiconductor substrate of conductive layer and make insulating barrier;

＜b〉thus make contact hole by the described insulating barrier of etching and expose described conductive layer; And

＜c〉making titanium silicide resistive layer in contact hole; And

＜d〉selective reaction by nitrogenous gas, tungsten source gas and reducing agent gas, the flow velocity of control nitrogenous gas and tungsten source gas makes that the flow velocity of nitrogenous gas is 2 to 7 times of tungsten source gas flow rate, deposit tungsten nitride layer optionally on the resistive layer in contact hole and the sidewall of contact hole, thereby the formation position of control tungsten nitride layer and prevent from the insulating barrier outside the contact hole, to form tungsten nitride layer.

2. according to the method for the manufacturing semiconductor device tungsten nitride layer of claim 1, wherein said conductive layer is to mix P ⁺One of the silicon substrate of impurity and metal connecting line layer, described metal connecting line layer is formed by one of aluminium (Al), tungsten (W), molybdenum (Mo), cobalt (Co), titanium (Ti), copper (Cu), platinum (Pt), the silicide of described metal and alloy of described metal.

3. according to the method for the manufacturing semiconductor device tungsten nitride layer of claim 1, it is characterized in that: one of them makes described insulating barrier by silicon oxide layer, silicon nitride layer with by impurity being injected this three of the resulting coating of one of described silicon oxide layer and described silicon nitride layer.

4. according to the method for the manufacturing semiconductor device tungsten nitride layer of claim 1, it is characterized in that: described tungsten source gas is WF ₆And WCl ₆One of.

5. according to the method for the manufacturing semiconductor device tungsten nitride layer of claim 1, it is characterized in that: described nitrogenous gas is N ₂, NH ₃With one of monomethylhydrazine.

6. according to the method for the manufacturing semiconductor device tungsten nitride layer of claim 1, it is characterized in that: described reducing agent gas is H ₂, SiH ₄, SiH ₁Cl ₃, SiH ₂Cl ₂And PH ₃One of.

7. according to the method for the manufacturing semiconductor device tungsten nitride layer of claim 1, it is characterized in that: the flow-rate ratio of described reducing agent gas and described tungsten source gas is 0-500.

8. according to the method for the manufacturing semiconductor device tungsten nitride layer of claim 7, it is characterized in that: the flow-rate ratio of described reducing agent gas and described tungsten source gas is 20-50.

9. according to the method for the manufacturing semiconductor device tungsten nitride layer of claim 1, at described step＜b〉further comprising the steps of afterwards: make groove by the described conductive layer that exposes of etching, reach certain depth.

10. method of making the semiconductor device metal line may further comprise the steps:

＜a〉make in the above on the Semiconductor substrate of conductive layer and make insulating barrier;

＜b〉thus make contact hole by the described insulating barrier of etching and expose described conductive layer; And

＜c〉making tungsten silicide resistive layer on the described conductive layer that exposes by contact hole;

＜d〉selective reaction by nitrogenous gas, tungsten source gas and reducing agent gas, the flow velocity of control nitrogenous gas and tungsten source gas makes that the flow velocity of nitrogenous gas is 2 to 7 times of tungsten source gas flow rate, deposit tungsten nitride layer optionally on the resistive layer in contact hole and the sidewall of contact hole, thereby the formation position of control tungsten nitride layer and prevent from the insulating barrier outside the contact hole, to form tungsten nitride layer; And

＜e〉on tungsten nitride layer, make metal level.

11. the method according to the manufacturing semiconductor device metal line of claim 10 is characterized in that: the described step＜c that makes described resistive layer〉may further comprise the steps:

Deposit tungsten nitride layer on the described conductive layer that exposes by described contact hole; And

The top gained product that is manufactured with described tungsten nitride layer is heat-treated, make that tungsten and the silicon substrate in the described tungsten nitride layer reacts, make the resistive layer of tungsten silicide thin layer.

12. according to the method for the manufacturing semiconductor device metal line of claim 10, it is characterized in that: described conductive layer is to mix P ⁺One of the silicon substrate of impurity and metal connecting line layer, described metal connecting line layer is formed by one of aluminium (Al), tungsten (W), molybdenum (Mo), cobalt (Co), titanium (Ti), copper (Cu), platinum (Pt), the silicide of described metal and alloy of described metal.

13. the method according to the manufacturing semiconductor device metal line of claim 10 is characterized in that: one of them makes described insulating barrier by silicon oxide layer, silicon nitride layer with by impurity being injected this three of the resulting coating of one of described silicon oxide layer and described silicon nitride layer.

14. the method according to the manufacturing semiconductor device metal line of claim 10 is characterized in that: described step＜d〉and＜c〉original position is carried out in same chamber.

15. according to the method for the manufacturing semiconductor device metal line of claim 10, it is characterized in that: described tungsten source gas is WF ₆And WCl ₆One of.

16. according to the method for the manufacturing semiconductor device metal line of claim 10, it is characterized in that: described nitrogenous gas is N ₂, NH ₃With one of monomethylhydrazine.

17. according to the method for the manufacturing semiconductor device metal line of claim 10, it is characterized in that: described reducing agent gas is H ₂, SiH ₄, SiH ₁Cl ₃, SiH ₂Cl ₂And PH ₃One of.

18. according to the method for the manufacturing semiconductor device metal line of claim 10, it is characterized in that: the flow-rate ratio of described reducing agent gas and described tungsten source gas is 0-500.

19. according to the method for the manufacturing semiconductor device metal line of claim 10, it is characterized in that: described metal level is formed by one of aluminium (Al), tungsten (W), molybdenum (Mo), cobalt (Co), titanium (Ti), copper (Cu), platinum (Pt), the silicide of described metal and alloy of described metal.

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