JP2765625B2 - Method of manufacturing semiconductor device and method of preventing corrosion of Ti film in through hole - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the semiconductor equipment manufacturing method and through-holes having a multi-layered fine wiring structure Ti
More particularly, the present invention relates to blanket tungsten chemical vapor deposition (WCVD) growth in through holes.

[0002]

2. Description of the Related Art In recent years, attention has been paid to a technique for fabricating a multi-layer wiring structure as semiconductor devices become higher in density and higher in integration. In this multilayer wiring structure, a technique for connecting through holes between metal wirings of different layers is disclosed in, for example,
There is one using a contact structure as disclosed in JP-A-130720 (hereinafter referred to as prior art 1). In the application of the prior art 1, a through hole is provided in an interlayer insulating film, a barrier layer is formed in the through hole, and a tungsten metal (W) is buried by a blanket W CVD method to form a plug. The metal wiring on the bottom surface is connected to the metal wiring formed on the interlayer insulating film.

FIGS. 3A to 3D are views showing a method for manufacturing a semiconductor device according to the prior art 1. FIG. As shown in FIG. 3A, a base insulating film 12 formed on a Si substrate 11 is formed.
The lower metal wiring 13 is formed thereon, and the interlayer insulating film 1 is superposed thereon.
After the formation of the through holes 4, the through holes 15 are formed. next,
As shown in FIG. 3B, a Ti film 16 is formed by a sputtering method. Then, since there is a concern that the lower metal wiring may be melted, it is impossible to form a TiN film serving as a barrier layer by performing lamp annealing at about 700 ° C. for about 30 seconds in N ₂ gas. TiN film 1 by the method
7 is formed. This point is a portion to which the disclosed content of the prior art 1 is applied. Next, as shown in FIG. 3C, the inside of the through hole 15 and the Ti
After forming a W film 18 on the N film 17, the W film 18 on the TiN film 17 outside the through hole 15 is removed by a plasma etching method, and the W film 1 is formed only in the through hole 17.
8 and the W plug 19 is formed. Finally, as shown in FIG. 3D, an Al film is formed by a sputtering method, and is subjected to predetermined patterning to form an upper metal wiring 20, thereby manufacturing a semiconductor device.

At this time, the TiN film 17 of the barrier layer formed by the sputtering method has poor coverage which is a characteristic of the film formed by the sputtering method, and the formation of the TiN film is extremely low at the bottom of the through hole. Negligible, T
It is conceivable that the i-film 16 is exposed.

[0005]

According to the conventional method of manufacturing a semiconductor device, a process of forming a W film 18 on a TiN film 17 which is a barrier layer formed in a through hole 15 is performed by a schematic cross section shown in FIG. as shown, locations WF ₆ 21 of the reaction gas TiN film 17 by points or sputtering TiN film 17 is not formed in the barrier layer is not sufficient film thickness is formed from poor as a barrier layer coverage, for example, through It diffuses to the bottom of the hole, reaches the Ti film 16, and is expressed by the formula WF ₆ + Ti → TiWx + F.
Due to the reaction between F ₆ and Ti, the eroded portion 2 of WF ₆ 21
2 is generated, and there is a problem that adhesion is deteriorated.

The above problem can be considered as a problem that occurs only when the W film 18 is formed in the through hole 15 by the blanket W CVD method. This is Al
This is largely due to the fact that lamp annealing cannot be performed in N ₂ gas due to concern about melting of lower metal wiring 13 composed of.

Therefore, a technical problem of the present invention is to provide a TiN film 1 serving as a barrier layer generated when the blanket W is grown.
And to provide a corrosion prevention method of the Ti film production method and the through hole of the semiconductor equipment having a multilayer wiring structure that prevents formation of erosion portion by adhesion of degradation of 7.

[0008]

[Means for Solving the Problems] In order to solve the above problems
In the method of manufacturing a semiconductor device according to the present invention,
The lower metal wiring by Al thin film formation and patterning
Forming a lower metal wiring process and forming an interlayer insulating film on the substrate;
Forming an interlayer insulating film, and etching the interlayer insulating film.
A through hole is formed by etching, and the
An etching step for exposing the lower metal wiring;
Forming Ti / TiN as a barrier layer in a hole
A layer forming step and embedding with W after forming the barrier layer
With multi-layered micro-wiring structure with embedded burying process
In the method for manufacturing a device, the embedding step may include the step of:
The exposed Ti on the surface of the layer is placed in the same device (in-situ
Step of nitriding at the same temperature as the film formation temperature of W in the step (-)
It is characterized by including a floor.

[0009]

Here, in the semiconductor device and the method of manufacturing the same according to the present invention, the step of embedding with W is preferably performed by a blanket W CVD method.

In the method for preventing corrosion of a Ti film in a through hole according to the present invention, Ti / TiN is formed as a barrier layer in a through hole reaching a lower metal wiring formed on a semiconductor substrate, and a W plug is formed in the barrier layer. In the method for preventing corrosion of a Ti film in a through hole when forming a hole, the exposed Ti on the surface of the barrier layer is removed by using the W plug in the same device.
In the same apparatus at a temperature equal to the formation temperature of the
After nitriding in (W ) , the W plug is
It is characterized by being formed by a CVD method.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing a semiconductor device according to a first embodiment of the present invention. Referring to FIG.
The configuration of the semiconductor device according to the first embodiment of the present invention will be described. In the semiconductor device, a base insulating film 12 is formed on a Si substrate 11. Although not shown, S
A structure necessary for a semiconductor device such as a diffusion layer and a gate electrode is formed inside and on the surface of the i-substrate 11. Further, a contact exists at a required position of the base insulating film 12, and a contact structure for connecting the lower metal wiring to the diffusion layer, the gate electrode, or another structure is formed.

More specifically, the underlying insulating film 12
A lower metal wiring 13 made of Al is formed thereon. On the underlying insulating film 12 on which the lower metal wiring is formed,
An interlayer insulating film 14 is formed. A through hole 15 is formed in the interlayer insulating film 14 on the lower metal wiring. Further, the inside of the through hole 15 and the interlayer insulating film 1 are formed.
4 is provided with a Ti film 16 and a T film
A barrier layer having a laminated structure composed of the iN film 17 is formed. In this barrier layer, a W plug 19 is formed via an in-situ nitrided portion 1 formed in the same device .

FIG. 2 schematically shows a semiconductor manufacturing apparatus. Referring to FIG. 2, a semiconductor manufacturing apparatus 30 is controlled by a system control unit 40 provided outside.
Its operation is controlled. The wafer 31 is transferred from the clean room 37a to the load lock chamber 32a provided with the index robot 33a, and further transferred to the reaction chamber 35 via the transfer chamber 34 provided with the transfer robot 34a. A reaction mechanism 36 is provided in the reaction chamber 35, and can perform various processes such as an etching process for introducing a gas, CVD, and plasma generation. The predetermined processing is performed in the reaction chamber 35, and the transfer robot 34 transfers the processing to the index robot 33a in the load lock chamber via the transfer chamber 34 again. It is transported again to the reaction chamber by the index robot 33a, or the shuttle 38a,
To the clean room 3 via the load lock chamber 32b by the index robot 33b.
The waste gas is discharged to a clean room 41 for a new process.

Next, returning to FIG. 1, the method of manufacturing the semiconductor device according to the first embodiment of the present invention will be described in more detail.

The steps up to the formation of a barrier layer having a laminated structure composed of the Ti film 16 and the TiN film 17 are the same as in the conventional case.
After forming the barrier layer, a W film 18 is formed by a blanket W CVD method. Here blanket W CV
The step of forming the W film 18 by the D method will be more specifically described with reference to FIG.

First, the number of wafers 31 that can be evacuated is transferred to a load lock chamber 32a equipped with an index robot 33a. Load lock room 3
2a is evacuated to a predetermined pressure. Thereafter, the wafer 31 is transferred into the reaction chamber 35 by the transfer robot 34a via the transfer chamber 34, and moves to a position where the wafer 31 can react without flowing gas.
Next, the wafer is heated to make the temperature distribution in the wafer plane uniform.

Next, a reaction gas is introduced by the reaction mechanism 36, only SiH ₄ is introduced into the reaction chamber 35 of about 30 sccm, and SiH ₄ is adsorbed on the surface of the wafer 31. The reason for this is that fluorine adsorbed on the wafer 31 is removed and W
The in-plane uniformity is improved by adsorbing SiH ₄ , which is a reducing agent of F ₆ , onto the wafer, and the erosion of WF ₆ , which is strongly reactive, is prevented. Next, a tungsten nucleus is formed by SiH ₄ reduction, and then buried by H ₂ reduction with good coverage. This blanket W
When heating the wafer 31 by the CVD method, for example, the reaction chamber 3
By the 5 N ₂ used in the air opening of introducing into the reaction chamber 35, because it is heat-treated at a temperature of about 450 ° C. using the W film formation, a portion or sputtering surface or TiN film of TiN film 17 is not formed It is possible to nitride the surface of the Ti film where the Ti film 16 is exposed, which may occur at the bottom of the through-hole due to poor coverage, which is a characteristic of the formed film.

Therefore, it is possible to form a barrier layer sufficient to prevent erosion of WF ₆ , which is strongly reactive during W deposition, and to prevent deterioration of adhesion. Further, by performing the blanket WCVD in the same apparatus before growing the W film, oxidation of the wafer surface can be minimized. Thereafter, the W film 18 on the interlayer insulating film 14 is removed by the plasma etching method using the reaction mechanism 36, and the W film 18 is formed only in the through hole 15, and the W plug 19 is formed as shown in FIG. I do. Finally, as described with reference to FIG. 2, an Al film is formed by a sputtering method and is subjected to predetermined patterning to form an upper metal wiring 20, thereby manufacturing a semiconductor device.

Next, a semiconductor device according to a second embodiment of the present invention will be described. The semiconductor device according to the second embodiment of the present invention has the same configuration as the above-described first embodiment, but differs in the manufacturing method. That is, in the first embodiment described above, the wafer 31 is
After being transported to a position where it can react, the N ₂ is introduced into the reaction chamber 35 when the wafer 31 is heated in order to make the temperature distribution in the wafer surface uniform, so that the temperature used for W film formation is reduced. Heat treatment is performed at 450 ° C. to enable nitriding.

However, in the second embodiment, the W film 18
Before the formation of the wafer, the load lock chamber 32a in which the wafer 31 is first transferred and which can be evacuated and provided with the index robot 33a or the transfer robot 34a is provided in the transfer chamber 34.
In this case, for example, a portion where the wafer 31 is temporarily held is heated by a resistance heating method, and the load lock chamber 3 is heated.
2a or N ₂ used to open the transfer chamber 34 to the atmosphere can be introduced into the load lock chamber 32a and can be nitrided by heat treatment.

In the second embodiment, nitriding can be performed while the load lock chamber 32a or the transfer chamber 34 is being evacuated, so that there is no decrease in throughput with respect to the formation of the W film. Since the heating of the wafer 31 has already been completed in the load lock chamber 32a or the transfer chamber 34,
Since the heating of the wafer 31 in the reaction chamber 35 is not required, there is an advantage that the throughput is further improved.

As described above, in the first and second embodiments of the present invention, a TiN film formed by a sputtering method as a barrier layer is formed at a place where a TiN film is not formed or at a position where a TiN film formed by a sputtering method is formed. A blanket W that does not melt the lower metal wiring is formed on the surface of the Ti film where the possible Ti film is exposed at the bottom of the through hole resulting from poor coverage, which is the same as when the W film is formed by the CVD method.
The in- situ nitriding unit 1 is made of Ti /
By forming between the TiN film 17 and the W film 18, corrosion of the Ti film by the WF ₆ gas can be prevented, and deterioration of the adhesion of the W film 18 can be prevented.

[0025]

As described above, according to the present invention,
When the through hole is buried by the blanket W CVD method, it occurs at the surface of the TiN film which is the underlying barrier layer, at a place where the TiN film is not formed, or at the bottom of the through hole resulting from poor coverage which is a defect of the film formed by the sputtering method. By introducing N ₂ into the reaction chamber or a load lock chamber or a transfer chamber equipped with a heating mechanism at the time of heating the wafer before the W film formation, the lower layer metal made of Al There is an advantage that nitriding can be performed at a temperature at which wiring does not melt, and deterioration of adhesion can be prevented.

Further, according to the present invention, a blanket W
Since nitridation can be performed in the same apparatus before CVD growth, oxidation of the wafer surface from nitridation to W growth can be minimized, and it can be realized without adding a process flow. Have.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a view schematically showing a semiconductor device manufacturing apparatus.

FIG. 3 is a view showing each manufacturing process of a semiconductor device according to a conventional example.

FIG. 4 is a schematic diagram for explaining a problem of a semiconductor device according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Si substrate 12 Base insulating film 13 Lower metal wiring 14 Interlayer insulating film 15 Through hole 16 Ti film 17 TiN film 18 W film 19 W plug 20 Upper metal wiring 21 WF ₆ 22 Ti erosion part 30 Semiconductor manufacturing apparatus 31 Wafer 32a, 32b Load lock chamber 33a, 33b Index robot 34 Transfer chamber 34a Transfer robot 35 Reaction chamber 36 Reaction mechanism 37a, 37b, 41 Clean room 38a, 38b Shuttle 40 System control unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) H01L 21/3205 H01L 21/3213 H01L 21/768 H01L 21/28-21/288 H01L 29/40-29 / 51

Claims (3)

(57) [Claims] 1. A lower metal wiring step for forming an Al thin film on a semiconductor substrate by forming and patterning an Al thin film, an interlayer insulating film forming step for forming an interlayer insulating film on the substrate, and etching the interlayer insulating film. An etching process for exposing the lower metal wiring on the bottom surface thereof, a barrier layer forming process for forming Ti / TiN as a barrier layer in the through hole, and embedding by W after forming the barrier layer. In a method of manufacturing a semiconductor device having a multilayer fine wiring structure having a process,
In the embedding step, before embedding the surface of the barrier layer with the W, the Ti exposed on the surface of the barrier layer is made the same.
A step of nitriding at a temperature equal to the film forming temperature of W in the apparatus of (1). 2. The method of manufacturing a semiconductor device according to claim 1 , wherein said step of burying with W comprises a blanket W.
A method for manufacturing a semiconductor device, wherein the method is performed by a CVD method. 3. A method for preventing corrosion of a Ti film in a through hole when Ti / TiN is formed as a barrier layer in a through hole reaching a lower metal wiring formed on a semiconductor substrate and a W plug is formed in the barrier layer. The exposed Ti on the surface of the barrier layer is removed from the W plug in the same device.
A method of preventing corrosion of a Ti film in a through hole, wherein the W plug is formed by blanket W CVD after nitriding at a temperature equal to the formation temperature .