KR100691483B1 - Method for fabricating semiconductor device - Google Patents

Abstract

The present invention is to solve the problem that occurs during the etching of removing AlOx at the bottom of the via prior to depositing the adhesive layer and the diffusion barrier during the via plug forming process of the semiconductor metal wiring forming liner. A method of forming a semiconductor device, comprising: forming a contact, a metal wiring, and an interlayer insulating film on a semiconductor substrate on which transistor formation is completed; Forming via holes on the semiconductor substrate; Depositing a Hf thin film on the aluminum oxide layer at the bottom of the via hole; The Hf gathers and reduces oxygen in the AlOx layer to form a metal interface of Al / Hf; And forming a tungsten plug on the metal interface.

Semiconductors, metallization, liner formation, vias,

Description

Method for manufacturing a semiconductor device {Method for fabricating semiconductor device}             

Figures 1a to 1c is a cross-sectional view showing a conventional invention

2A to 2C are cross-sectional views showing the present invention.

* Explanation of symbols for the main parts of the drawings

20: aluminum wiring 21: aluminum oxide layer

22: interlayer insulating film 23: via hole

24: Hf 25: Tungsten Plug

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a highly integrated semiconductor device, and more particularly, to a via plug technology among semiconductor metal wiring forming methods.

In general, plugging vias connecting the lower aluminum (Al) wiring and the upper wiring consists of a TiN / Ti barrier and a tungsten plug or aluminum plug technology. At this time, Ti is used as an adhesive layer and TiN is used as a diffusion barrier during tungsten deposition. However, cleaning is required to remove aluminum oxide (AlOx) formed on top of the lower metal line before the TiN / Ti deposition.

To remove these AlOxes, dry cleaning by plasma or wet cleaning by solution is used. This is because a thin AlOx layer causes high via resistance.

In order to eliminate the high via resistance of the AlOx layer, conventionally, dry or wet etching method removes AlOx formed at the interface between the via and the lower aluminum wiring, and then deposits TiN / Ti as a diffusion barrier and then deposits tungsten or aluminum. . Therefore, there is a problem in that a step of removing AlOx is added in addition to barrier layer deposition.

 In the case of tungsten plugs, the etch-back process after tungsten plugs forms a tungsten oxide layer on the surface of the tungsten remaining as via plugs. If aluminum is deposited without a break, Ti has the effect of gathering the oxygen of tungsten oxide, thereby reducing the interfacial contact resistance. At this time, the cast energy of tungsten is -146kJ / mol and the cast energy of Ti is lower, -250kJ / mol. Therefore, Ti deposited on the tungsten oxide reduces tungsten oxide when easily gathered with oxygen, and oxygen gathered on Ti does not appear as an increase in resistance because it is not in the form of an oxide film.                         

On the other hand, in the case of AlOx, the Gibbs energy of Ti is -256kJ / mol and Al's Gibbs energy is higher than -316kJ / mol, making it difficult to reduce AlOx and physically sputtering AlOx to Ar. An additional process is necessary to remove it.

1a to 1c show a process according to the prior art.

Referring to FIG. 1A, an aluminum wiring 10 is formed on a semiconductor substrate formed by a conventional process, an interlayer insulating film 12 is deposited, and a via hole 13 is patterned. At this time, a dry or wet etching process is performed to clean the AlOx 11 before the via plug is formed.

Subsequently, referring to FIG. 1B, in the case of cleaning by dry etching, the inlet of the via is etched and widened by sputtering with Ar ions having a straightness, thereby adhering to neighboring vias, or subsequently defining aluminum wiring. After that, the aluminum wiring and the via have a problem of forming a borderless region with each other, and oxide etched in the bottom region is re-depositioned toward the sidewall of the surrounding via (part A of FIG. 1B). It may be difficult to secure step coverage during barrier deposition in the process.

Subsequently, referring to FIG. 1C, when the wet etching is performed, a solution for removing an oxide is used. As shown in FIG. 1C, the insulating oxide layer constituting the via is also etched to some extent so that the overall size of the via CD is critical. It is easy to bring about an enlargement of (B part of FIG. 1C) or a deformation of the via profile (part C of FIG. 1C) by concentration of the solution at the bottom of the via.

An object of the present invention is to provide a metal wiring forming method for removing AlOx using Hf to solve the problem that occurs during the etching of removing the AlOx on the bottom of the via in the process of forming the via plug of the semiconductor metal wiring forming method. It is done.

A method of forming a liner of metal wiring of a semiconductor device, the method comprising: forming a contact, a metal wiring, and an interlayer insulating film on a semiconductor substrate on which transistor formation is completed; Forming via holes on the semiconductor substrate; Depositing a Hf thin film on the aluminum oxide layer at the bottom of the via hole; The Hf gathers and reduces oxygen in the AlOx layer to form a metal interface of Al / Hf; And forming a tungsten plug on the metal interface.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming metal wirings in a semiconductor device manufacturing process, and to a method of removing an AlOx layer, which is a natural oxide film formed on an aluminum wiring layer in a bottom portion of a via, without an RF etch pre-clean process in a via. will be.

Instead of using the RF etch preclean process, which is a common method, Hf (hafnium) is deposited to reduce oxygen of AlOx, and an oxide film of oxygen is not formed in Hf, and the metal interface of Al / Hf is formed. The present invention relates to a metallization liner deposition technique in vias that can form a good via resistance by forming.

The invention also features the use of Hf as the adhesive and barrier metal. Hf is a metal that is highly reactive with oxygen. The aluminum interface cleans the oxide layer between the bottom of the via and the bottom aluminum wiring after the via etching by reducing oxygen of AlOx without the conventional high frequency pre-clean etching process. It is a material capable of forming a good via resistance by forming a.

The basis for the reduction of Hf's AlOx is that the Gibbs energy of Hf is -352kJ at 298K but -310kJ for aluminum. Therefore, AlOx, a natural oxide film of Al, has a clean aluminum surface as oxygen is gathered into the Hf thin film by the Hf layer deposited thereon.

Therefore, if Hf is deposited, the via etch profile can be maintained without distortion of via profile or CD widening without high frequency etch process, but effectively removes AlOx at the interface between the bottom of the via and the bottom aluminum wiring to ensure low via resistance. Can be. This ensures sufficient resistance even if a thin thickness of less than about 50 microns is deposited on the floor area.

Hereinafter, preferred embodiments of the present invention will be introduced in order to enable those skilled in the art to more easily carry out the present invention.

2A to 2C are cross-sectional views showing an embodiment according to the present invention.

Referring to FIG. 2A, a via hole 23 is formed by patterning the lower wiring 20 and the insulating layer 23 through a series of photo and etching processes on a semiconductor substrate on which a predetermined process is completed. At this time, before forming the via plug, a process of removing AlOx 21 at the bottom of the via hole is necessary.

Then, as shown in Figure 2b, instead of using a conventional wet or dry pre-cleaning process, Hf material for reducing the oxygen of the aluminum oxide layer is deposited to a thickness of 50 ~ 500 kPa by physical vapor deposition or chemical vapor deposition. Here, the deposited Hf is thermodynamically more stable than the AlOx layer, which is a natural oxide film, and the AlOx is reduced to aluminum, and the gathered oxygen is dissolved into the Hf thin film and does not form an additional oxide film, thereby obtaining good via resistance due to the Al / Hf interface. have.

The Hf surface is then formed as a HfNx layer by rapid heat treatment (RTP) or Furnace heat treatment on Hf deposited with the liner, thereby forming Hf / HfNx 24 as an adhesive layer and a barrier layer.

As shown in Fig. 2C, in the Hf / HfNx 24 layer formed by heat treatment, the HfNx layer serves as a diffusion barrier to form a tungsten plug 25 by chemical vapor deposition.

Here, instead of the heat treatment process after the Hf layer deposition, the HfNx layer is deposited in-situ in a high vacuum by physical vapor deposition or chemical vapor deposition, or by vacuum (ex-situ) after vacuum break. It can also be deposited in other chambers or equipment and used as a diffusion barrier in tungsten plug processes.

In addition, after deposition of the Hf layer, TiN may be deposited using a diffusion barrier to form a Hf / TiN structure. At the time of Hf deposition, the deposition temperature from room temperature to about 400 ° C is possible, and the process of reducing oxygen of AlOx by thermal process after deposition can be activated.                     

In addition, activation characteristics for oxygen reduction of the aluminum oxide film by physical layer separation when deposited on the aluminum oxide layer by the so-called ionized PVD method, which ionizes Hf and accelerates and advances the physical vapor deposition of Hf. There is also a way to get

In addition, before Hf deposition, after applying a high frequency pre-clean etching process, Hf deposition may be performed, in which case Hf is minimized after minimizing high frequency etching to minimize via profile deformation caused by Ar + ions during high frequency etching. It may be.

That is, after activating the aluminum oxide layer by Ar + ions, it is possible to improve the reduction characteristics of the Hf layer. In this case, the degree of removal during the high frequency etching is minimized to 10 ~ 100Å based on the thermal silicon oxide (Thermal SiOx) to minimize the via profile deformation while physically impacting the AlOx layer to fully activate the reduction by the Hf film.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made without departing from the spirit and scope of the present invention. It will be apparent to those who have knowledge.

The present invention does not perform a pre-clean etching process to remove AlOx before forming a via plug, and reduces the oxygen of aluminum oxide by depositing a material called Hf, thereby preventing the spread of the entire via CD by dry pre-clean etching. It can maintain the via CD as the original design, and also prevent the bottom area of the via from squeezing by the solution concentration during the wet vision, and it is easy to secure the step coverage of the barrier process. In addition, Hf deposition by simple stepper equipment has the advantage of simplifying the process and reducing the manufacturing cost without the need for complicated equipment for the plasma used for dry pre-cleaning.

Claims (9)

Forming a contact, a metal wiring, and an interlayer insulating film on the substrate on which the transistor formation is completed; Forming via holes on the semiconductor substrate; Depositing an Hf thin film on the AlOx layer formed on the bottom of the via hole; And Forming a tungsten plug on the Hf thin film Method for manufacturing a semiconductor device comprising a. The method of claim 1, The Hf layer is deposited by a physical vapor deposition or chemical vapor deposition method, the thickness of the semiconductor device manufacturing method characterized in that the deposition in the range of 50 ~ 500Å. The method of claim 1, After the Hf deposition, the Hf surface is formed of HfNx through rapid heat treatment or heat treatment of the reactor to form a diffusion barrier and an adhesive layer. The method of claim 1, And depositing the HfNx layer by physical vapor deposition or chemical vapor deposition on the diffusion barrier layer and the adhesive layer after the Hf deposition. The method of claim 4, wherein The HfNx layer is a semiconductor device manufacturing method characterized in that the deposition in high vacuum by in-situ after deposition of the Hf layer or in another chamber or equipment by the excitation after vacuum break. The method of claim 1, Method of manufacturing a semiconductor device characterized in that to deposit TiN as a diffusion barrier after the deposition of Hf. The method of claim 1, The deposition method of the Hf deposition at room temperature up to 400 ℃, the method of manufacturing a semiconductor device, characterized in that to activate the oxygen reduction of the aluminum oxide layer by a thermal process after Hf deposition. The method of claim 2, In the Hf deposition, the physical vapor deposition method is a semiconductor device manufacturing method characterized in that the deposition by the ionized physical vapor deposition method. The method of claim 1, In the Hf deposition, a method of manufacturing a semiconductor device, characterized in that to perform the high frequency pre-clean etching process in the range of 10 ~ 100Å to activate the aluminum oxide layer to improve the reduction characteristics of the Hf layer.

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