JP3445557B2 - Titanium-tantalum barrier layer thin film and method of forming the same - Google Patents

Description

Detailed Description of the Invention

RELATED APPLICATION This application was filed on March 29, 1999 inactivation N
GUSI C. O. S. Inventor M Robbins (ML) entitled Detection of Plasma Charge Accumulation Induced by Technology
obbins), Lauri M. Nelson (Lauri)
M. Nelson), Siddhatha Bomiku (Si
ddhartha Bhowmik), Syresh
M. Merch
ant), Pradip Kay Roy
K. Roy, Sidhartha Sen
Sen and Minseok O
Claiming priority of US Patent Application No. 60 / 126.681 according to h).

This application is also the inventor, Siddhartha Bhowmi, entitled Use of Titanium-Tantalum Alloys as a Diffusion Barrier Material for Copper Interconnects, filed May 24, 1999.
k), Silesh M Merchant (Saile)
sh M. Merchant), Minseok Oh (M
inseok Oh), Pradip Kay Roy (P
radip K. Roy) and Shidaharta Sen (Si
Dhartha Sen) US Patent No. 60/13
Claiming the priority of 5.565.

FIELD OF THE INVENTION The present invention relates generally to semiconductor deposited circuit devices.
More specifically, the present invention relates to integrated circuit devices including titanium-tantalum barrier layer thin films and methods of making such integrated circuit devices.

[0004] In the background generally to semiconductor integrated circuit devices of the present invention, for use with a conductive material such as those used as an interconnect or wire layer of the device is preferably formed a barrier layer film. The conductive material is typically separated from other parts of the semiconductor integrated circuit device by a dielectric material. In a damascene process, interconnect structures or wire patterns are formed in trenches or other openings formed in a dielectric thin film. In non-damascene processes, conductive interconnect structures are formed on dielectric thin films.

A portion of the conductive material penetrates the dielectric material,
A barrier layer thin film is required between the dielectric material and the conductive material to prevent migration into other active parts of the device. Through such movement, through the dielectric material,
Short circuits between or within levels can occur. When some of the conductive material moves into the underlying silicon, such as the silicon substrate commonly used in the semiconductor industry, various device characteristics can be adversely affected. For example, junction leakage currents can occur and the threshold voltage (Vt) level of transistors formed in the silicon substrate can change. In many cases, the functionality of the device can be destroyed.

The above effects are of particular interest when copper (Cu) is used as the conductive interconnect material, since copper is the most mobile through semiconductor structures. Copper is preferred in semiconductor integrated circuit fabrication because it has excellent conductivity. Thus, when copper is used as the conductive material in a damascene structure, the conductive copper material is effectively contained within the barrier layer film. Barrier layer thin films have become used to separate conductive thin films, such as copper, from dielectric thin films formed on or in them. Barrier layer materials also find use in contact areas where a conductive thin film contacts another conductive thin film or a region of a semiconductor device. In the present application, the barrier layer material suppresses spikes between conductive materials or between conductive and semiconductor materials.

Many conductive barrier materials are available from semiconductor fabrication techniques. However, each of the conventional barrier materials has limitations that limit its effectiveness when used with copper thin films, which are currently the most desirable but most mobile through semiconductors. An example of a barrier material conventionally used with copper is tantalum (Ta). In this application, a drawback associated with using tantalum is that tantalum does not adhere well to conventionally used dielectric thin films such as silicon dioxide (also called "oxide"). Tantalum nitride (TaN) has also been used as a barrier material with copper due to the limitations associated with the use of tantalum. Tantalum nitride (TaN) has the advantage that it adheres well to oxides and other dielectric thin films.
However, a drawback associated with using tantalum nitride as a barrier layer material is the poor atomic compatibility between tantalum nitride and copper along the boundaries formed between the materials.
Therefore, the Cu-TaN thin film structure is much more distorted than the Cu-Ta thin film structure. The atomic match between copper and tantalum nitride contains defects at some atomic planes.

Other materials that have been proposed and sometimes used as barrier layer materials with copper also exhibit disadvantages, making them unsuitable for use with copper thin films. For example, titanium nitride (TiN) also exhibits poor atomic integrity on the atomic planes along the boundaries that form with copper. Pure titanium (Ti) is generally considered unsuitable for use with copper as a barrier layer material. Because titanium combines with copper to form an intermetallic compound, which reduces the conductivity of the copper film. Titanium is a material that adheres well to dielectric materials such as oxides.

What is technically needed is a conductive thin film suitable for use with copper and other conductive materials that adheres well to and forms boundaries with oxide and other dielectric thin films; A barrier material that produces a low strain or heteroepitaxial relationship. The object of the invention is to realize such a barrier layer thin film and a method for forming it.

SUMMARY OF THE INVENTION In view of these and other objectives, to accomplish these and other objectives, the present invention provides titanium-tantalum barrier layer thin films and methods of forming the same. This barrier layer is particularly suitable for use with copper. The titanium-tantalum barrier layer thin film may be a synthetic thin film or a single thin film having a concentration gradient. The first surface of the thin film is titanium rich / tantalum depleted so that it adheres well to the underlying dielectric material as commonly used in the current art. Opposite faces of the thin film are titanium-deficient / tantalum-excess to form a heteroepitaxial junction with the conductive material and to avoid undesired formation of intermetallic compounds that reduce the conductivity of the conductive material.

The present invention also reveals a method of forming a synthetic thin film and a single thin film having a concentration gradient. The method of forming the synthetic thin film may include a sputter deposition process using one or more sputtering targets. This method and the resulting barrier layer thin film are suitable for both damascene and non-damascene process technologies.

DETAILED DESCRIPTION OF THE INVENTION The present invention reveals a method and structure for forming a barrier layer thin film of titanium and tantalum. Each of the barrier layer thin films of the present invention is relatively titanium-excessive in the portion of the thin film forming the surface adjacent to the dielectric material and relatively tantalum in the portion of the thin film forming the surface adjacent to the conductive material. Excess. Barrier layer thin films formed in accordance with the present invention can be used in damascene or non-damascene process applications.

FIG. 1 shows a damascene opening 21 formed in a dielectric thin film 17 formed on a lower layer 15. The lower layer 15 may be any layer on which the dielectric thin film 17 is formed. According to an embodiment, the bottom layer 15 may be a substrate, such as the silicon substrate commonly used in the semiconductor processing industry. According to another embodiment, the lower layer 15 may be a conductive thin film, and the opening 21 therein may be used to form a contact between the conductive layer to be formed therein and the conductive thin film below.
In another embodiment, the bottom layer 15 may also be a dielectric material, in which case the cross-section shown in FIG. 1 is simply a cross-sectional view of the damascene opening formed in the region where the underlying contact is not being made. is there. Dielectric thin film 17 is oxide (silicon dioxide)
Alternatively, it may be a suitable dielectric thin film used in the semiconductor manufacturing industry such as a nitride (silicon nitride) thin film. Dielectric thin film 17 may be formed by any of a variety of methods including chemical vapor deposition and spin-on techniques.

Opening 21 formed in the dielectric thin film 17
May be formed using conventional methods. The opening 21 has a two-stage structure generally called a double damascene opening. It should be understood that the present invention is not intended to be limited to structures formed within double damascene openings. Rather,
Openings with various configurations such as vias, trenches or single damascene openings may be used. The damascene opening 21 includes a side wall 33 and a bottom surface 24. The bottom surface 24 may be the upper surface of the lower layer 15. Barrier layer thin film 125 is a titanium-tantalum barrier layer thin film having the concentration gradient described in connection with FIG. Barrier layer thin film 125 is formed on the top surface of dielectric thin film 17, the exposed surfaces including sidewalls 23 and bottom surface 24 of opening 21. The barrier layer thin film 125 does not completely fill the damascene opening 21.

Example 1 Titanium-Tan with concentration gradient
Tal Barrier Layer Thin Film Referring now to FIG. 2, an enlarged view of a titanium-tantalum barrier layer thin film 125 is shown. Titanium-tantalum layer 1
25 is formed on the exposed surface 3 of the lower member 1. The bottom material 1 may be any suitable dielectric commonly used in the semiconductor process industry such as oxide thin films formed using CVD. The exposed surface 3 may be the top surface of a dielectric film, such as the top surface 19 shown in FIG. 1, or may be formed in a dielectric film as shown in FIG. 1 at portions 23 and 24 respectively. It may represent the side wall or the bottom of the open opening. In any case, the tip surface 11 of the deposited thin film is formed on the exposed surface 3.

The titanium-tantalum thin film 125 consists of titanium and tantalum and contains a gradient of the relative proportions of the two components throughout the depth of the thin film. The tip surface of the deposited thin film is the first, or tip portion, formed during the deposition process. The titanium-tantalum barrier layer thin film 125 is shown in FIG.
, The tip surface 11 of the titanium-tantalum barrier layer thin film 125 is deposited on the exposed surface 3, as shown in FIG.
Is the bottom shown in FIG. Conversely, the top of the membrane terminates in the back surface 12, or the top surface of the membrane 125.

The relative concentration of titanium in the thin film having the concentration gradient is greatest in the portion of the thin film adjacent to the exposed surface 3, and the thin film 125 and the exposed surface 3 of material 1 below.
Along a direction 13 that extends perpendicularly from the boundary region formed between. Therefore, the weight percentage of titanium in the lower portion 5 is greater than that in the central portion 7, and that in the central portion is greater than that in the upper portion 9. Therefore, the relative weight concentration of tantalum in thin film 125 is
5 within the boundary region formed between the tip surface 11 of 5 and the exposed surface 3 of the underlying material 1. The relative weight concentration of tantalum in the film increases along a direction 13 extending vertically from the exposed surface 3. Thus, the relative weight concentration of tantalum in the film is minimal in the lower part 5, increasing in the central part 7 and maximizing in the upper part 9. It should be understood that for both tantalum and titanium, the regions 5, 7 and 9 are arbitrarily chosen to exhibit a relative weight concentration gradient of components within the film. The thin film, as produced, includes relatively titanium rich / tantalum depleted regions within the portion of the thin film adjacent the exposed surface to be deposited thereon. On the contrary, the portion of the thin film closest to the uppermost surface 12 is relatively tantalum-rich and titanium-deficient. The relative weight concentrations of titanium and tantalum form a gradient that varies along direction 13 and are not intended to define three distinct and distinct regions within the film. In embodiments, the gradient may be a gradual or continuous gradient.

The titanium-tantalum thin film thus produced has the following shape. The portion of the thin film within the lower portion 5 is titanium rich and tantalum deficient, which causes the lower surface 11 to adhere well to the underlying dielectric thin film, such as an oxide thin film. The upper portion 9 of the titanium-tantalum thin film 125 is tantalum-excessive and titanium-deficient, and the rear surface 12 is the upper surface 1.
2. Form a heteroepitaxial relationship with a conductive thin film, such as copper, that may be formed on. The regions 9 and the top surface 12 are titanium deficient, which suppresses the copper-titanium interaction, thereby eliminating the formation of unwanted intermetallic compounds. Such intermetallic compounds reduce the conductivity of the copper thin film.

According to the first embodiment, the titanium-tantalum thin film 125 is formed using a sputtering process, which may be done by any conventional sputtering means available to those skilled in the art. A uniform sputtering target with a uniform titanium-tantalum composition throughout is used. Due to the relative atomic weights of elemental titanium (atomic weight: 48) and tantalum (atomic weight: 181) by applying power and energy to the target so as to allow sputtering of the target material, the above A thin film is produced. It is a natural result of the sputtering process that when the current is applied to a uniform target made of titanium and tantalum, the lighter element, titanium, is sputtered from the target initially and at a higher rate. Thus, during such a sputter deposition process, titanium will be the preferred component to be first sputter deposited on the exposed surface. Titanium is lighter and "lands first" on the surface on which the thin film is deposited. As the sputtering process continues, titanium is selectively sputtered away from the uniform target. This exposes more tantalum, which is then sputtered from the target. In this way, a thin film having a relatively titanium-excessive / tantalum-deficient tip surface and a relatively tantalum-excessive / titanium-deficient rear portion is formed from titanium and tantalum, and from a sputtering target having a uniform component throughout. Can be formed.

In accordance with the first embodiment, the titanium-tantalum barrier layer thin film 125 having a concentration gradient along the direction 13 perpendicular to the surface to be deposited and the boundary to be formed is any of various types having different titanium-tantalum ratios. It is necessary to point out that it can be formed from a uniform sputtering target. However, despite the fact that the sputtering target has an overall uniform composition, the thin film produced by sputtering contains more titanium on the tip surface than the back surface, and less tantalum on the tip surface than the back surface, This is a feature of the present invention.

According to a second embodiment, a titanium-tantalum barrier layer thin film 125 having a concentration gradient along the direction 13 as described in connection with FIG. 2 is used in a sputter deposition process using two separate sputtering targets. You may form using. According to the second embodiment, both the titanium sputtering target and the tantalum sputtering target are included in the sputtering apparatus force. A shutter may be used to prevent contamination of the target surface due to cross-contamination. The targets are separately controllable and each suitable for separately and independently depositing thin films on the exposed surface of a substrate located in a sputtering apparatus. The amount of material sputtered from each target is proportional to the amount of current or power applied to the sputtering target and can therefore be controlled. By simultaneously supplying current to each of the sputtering targets, the material is simultaneously sputtered onto the surface exposed from both targets, thereby producing a thin film containing both titanium and tantalum. Varying the relative power, amps or voltage supplied to the sputtering target produces thin films with varying concentrations of titanium and tantalum.

According to a second embodiment, during the initial stages of the sputtering process used to form the above-mentioned thin film, the conditions are such that a greater amount of titanium than tantalum is sputtered onto the exposed surface of the substrate. Is selected.
Therefore, a relatively titanium-rich thin film portion is first formed. As the sputtering process continues, the power delivered to the sputtering target is adjusted so that relatively more tantalum is sputtered, producing a thin film with a higher tantalum / titanium concentration. The sputtering process conditions are changed again so that the trailing edge of the synthetic film still has a large tantalum / titanium densification. In this way, the sputtering conditions are selected so that a tantalum-rich, titanium-tantalum thin film is produced at the trailing edge.

It needs to be emphasized again that the three individual thin film parts described in connection with FIG. 2 are merely examples. In the preferred embodiment, the relative amounts of titanium and tantalum sputtered on the surface are gradually changed by gradually changing the relative pattern applied to the two targets. In this way, a titanium-tantalum thin film having a gradually changing concentration is formed.

A titanium-tantalum barrier layer thin film 12 having a concentration gradient along direction 13 as described in connection with FIG.
According to the third example of forming 5, the titanium-tantalum barrier layer thin film 125 is formed using a physical or chemical vapor deposition technique. Examples of chemical vapor deposition (CVD) techniques include plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), and metalorganic vapor deposition (MOCVD).

For each of the above-described deposition techniques according to the third embodiment, the deposition conditions are changed during the steps of the deposition process as follows. That is, a titanium-tantalum thin film that is relatively titanium-rich is formed first,
The relative titanium concentration in the tantalum film is reduced during the deposition process to produce a titanium-tantalum barrier layer film with a concentration gradient as described above. For example, the deposition process may include an input gas that includes titanium and an input gas that includes tantalum. In the case of MOCVD, the deposition process may include an input gas containing a precursor containing titanium and another input gas containing a precursor containing tantalum. The relative flow rates of the two gases may be varied during the deposition process to produce a thin film as described above.

That various other deposition techniques may be used to produce a titanium-tantalum barrier layer thin film having a concentration gradient in which the thin film is relatively titanium rich at the leading edge and relatively tantalum rich at the trailing edge. Should be understood. Generally speaking, the rate of titanium deposition and the rate of tantalum deposition are controlled separately. During a deposition process involving the simultaneous deposition of two components to form a thin film consisting of two mixtures, the relative rates of deposition are such that a titanium-tantalum thin film as described in connection with FIG. be changed.
That is, relatively more tantalum will be deposited as the deposition process proceeds.

In one embodiment, a short heat treatment is applied to the deposition process used to form the titanium-tantalum thin film having a concentration gradient to facilitate the migration of titanium towards the interface region with the dielectric material. You may continue.

Example 2 Thin synthetic titanium-tantalum barrier layer
Membrane FIG. 3 shows a fourth embodiment of a titanium-tantalum barrier layer thin film formed according to the present invention. In FIG. 3, like-marked parts are similar to those described in connection with FIG. In FIG. 3, a titanium-tantalum thin film 225
Is composed of a lower titanium thin film 27 and an independently formed upper tantalum thin film 29. This fourth embodiment provides a titanium-tantalum barrier layer thin film 225 comprising a titanium over / tantalum depleted lower portion adjacent an underlying surface 19 and a tantalum over / titanium depleted upper portion. The advantages of the embodiment of

According to a fourth embodiment, the thin films 27 and 2
9 are formed separately. The lower titanium thin film 27 is formed by sputtering, physical vapor deposition (PVD), chemical vapor deposition (C
VD), or MOC using organic or pre-organic precursors
It may be formed by a conventional method such as VD (organic metal CVD). The upper tantalum thin film 29 is the lower titanium thin film 27.
It may be formed using the same conventional deposition process described in connection with. In one embodiment, thin films 27 and 29
Each has a thickness in the range of 5 nanometers to 100 nanometers. The barrier layer thin film 225 is the dielectric thin film 17
Is formed in the damascene opening 21 on the uppermost surface 19 of the. Although the barrier layer thin film 225 is formed on the bottom surface 24 of the damascene opening 21 and along the sidewall 23 of the damascene opening 21, it can be seen that the barrier layer thin film 225 does not completely fill the damascene opening 21.

FIG. 4 shows a conductive film 31 formed on the top surface 26 of the titanium-tantalum barrier layer film 25.
4 and all the following times, titanium-tantalum barrier layer film 25 represents either barrier layer film 125 shown in FIG. 1 or barrier layer film 25 as shown in FIG. The conductive thin film 31 is formed by sputter deposition, CVD, PVD,
It may be formed by electrolytic deposition, electrolytic plating or electroless plating processes. In the preferred embodiment, the conductive layer film 31 may be copper, but in another embodiment it may be nickel or aluminum. Thickness 3 of the conductive thin film 31
2 may be any suitable thickness selected so that the conductive thin film 31 completely fills the opening 21. Filling the opening 21 means that the conductive thin film 31 completely occupies the opening portion below the plane formed by the upper surface 19 of the dielectric thin film 17.

In another embodiment shown in FIG. 5, the conductive thin film 31 may be formed by electrolytic deposition. In this embodiment, the seed layer thin film 33 is also formed between the titanium-tantalum barrier layer thin film 25 and the conductive thin film 31. In one embodiment, seed layer film 33 may be formed of copper. The seed layer thin film 33 is a conventional C that can be used by those skilled in the art.
It may be formed using a VD or PVD method, or it may be formed using an electroless plating process. It can also be seen that the seed layer thin film 33 is formed on the uppermost surface of the titanium-tantalum barrier layer thin film 25 and does not completely fill the opening 21. The conductive thin film 31 formed by electrolytic deposition on the seed layer thin film 33 as in the embodiment shown in FIG.
Completely fills the opening 21.

Referring to FIG. 6, a cross section of an interconnect structure or conductive wire 35 is shown. It can be seen that the portions of the titanium-tantalum barrier layer thin film 25 and the conductive thin film 31 lying on the plane formed by the upper surface 19 of the dielectric thin film 17 have already been removed. In one embodiment, a polishing operation such as chemical mechanical polishing (CMP) may be used to remove the thin film and planarize the surface as shown. It can be seen that the top surface 37 of the conductive wire 35 is essentially coplanar with the top surface 19 of the dielectric film 17. In the opening 21, the conductive thin film 31 is in contact with the titanium-tantalum barrier layer thin film 25 on the side surface and the bottom surface. In this damascene structure shown in FIG. 6, copper is the preferred conductive material, but nickel and aluminum could be used instead. FIG. 5 further includes a seed layer thin film 33.
It should be understood that in the embodiment shown in FIG.

FIG. 7 illustrates another embodiment of a thin film structure including a barrier layer thin film formed in accordance with the present invention. In FIG. 7, the conductive thin film is formed on the surface of the dielectric material according to the non-damascene technique. This portion of the thin film formed on the top surface of the substrate may be, for example, as shown in region 40 of FIG. Returning to FIG. 7, titanium-
The tantalum barrier layer thin film 25 may also be the barrier layer thin film 125 shown in FIG. 1 and described in connection therewith or the barrier layer thin film 225 shown in FIG. 3 and described in connection therewith. Titanium
The tantalum barrier layer thin film 25 is formed on the surface of the dielectric thin film 17. The conductive thin film 31 shown in FIG. 4 and described in connection therewith is formed on the top surface 26 of the titanium-tantalum barrier layer thin film 25. After the entire synthetic layer thin film including the conductive thin film 31 and the titanium-tantalum barrier layer thin film 25 is formed, the conventional patterning and etching method is used to pattern the synthetic thin film so that the conductive wire 39 is generated. May be used. In the non-damascene structure shown in FIG. 7, aluminum and nickel are preferred materials for use as the conductive layer thin film 31, but copper may be used instead.

Although the present invention has been shown and described with respect to aluminum, nickel and copper conductive thin films, it should be understood that the invention is not intended to be limited to the embodiments shown and described herein. is there. The titanium-tantalum barrier layer thin film comprising a lower portion that is titanium rich / tantalum depleted and an upper portion that is titanium depleted / tantalum rich may be used in any application for which such a thin film is suitable. In addition to being formed on the planar surface of the dielectric material or in the trench openings according to damascene techniques, the barrier layer thin film may be formed on various other structures. The barrier layer thin film and the structure formed using the barrier layer thin film may be used in various semiconductor devices and may be formed on various substrates used in the semiconductor manufacturing industry. The process of forming the barrier layer thin film according to the present invention is also not intended to be limited to the forming process described above. Rather, various other process techniques may be used to produce the titanium-tantalum barrier layer thin film. In addition, various other process operations may be combined to take advantage of the advantages of the above-described titanium-tantalum barrier layer thin films. For example, the non-damascene pattern conductive wire shown in FIG. 7 further includes a seed layer thin film formed between the titanium-tantalum barrier layer and the conductive thin film in an embodiment in which the conductive layer thin film is formed by an electrolytic plating technique. May be included.

The preceding is merely to illustrate the principles of the invention. Those of ordinary skill in the art will recognize that the principles of the present invention, which are not explicitly extended or illustrated herein, may be devised to devise a variety of configurations within the spirit and scope of the invention. Furthermore, all terms and conditions used herein are intended to be predominantly educational in nature and to assist the inventor in understanding the principles and concepts of the invention. It should be understood that the present invention is not limited to the specifically cited examples and conditions.
Furthermore, the description of the principles, aspects and embodiments of the invention set forth herein is intended to include the embodiments as well as their structural and mechanical equivalents. In addition, such equivalents are intended to include both presently known equivalents and those hereafter developed, i.e., any element developed that performs the same function, regardless of structure. ing. Therefore, the scope of the present invention is not intended to be limited to the embodiments as shown and described herein. The scope and spirit of the invention are included in the claims.

[Brief description of drawings]

1 is a cross-sectional view of a first embodiment of a barrier layer thin film formed according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a first embodiment of a barrier layer thin film formed according to the present invention.

FIG. 3 is a cross-sectional view of a second embodiment of a barrier layer thin film formed according to the present invention.

FIG. 4 is a cross-sectional view showing a conductive thin film formed on a barrier layer thin film.

FIG. 5 is a cross-sectional view showing a seed layer thin film formed between a barrier layer thin film and a conductive thin film.

FIG. 6 is a cross-sectional view showing a damascene structure according to an embodiment after being planarized.

FIG. 7 is a cross-sectional view showing an example of a patterned conductive structure including a barrier layer thin film of the present invention in a non-Damascene application.

[Explanation of symbols]

1 lower material, material 3 surface 5 lower surface, area 7 central portion, area 9 upper portion, area 11 front surface, lower surface 12 rear surface, top surface, top surface 13 direction 15 bottom layer 17 dielectric thin film 19 top Surface, surface 21 Damascene opening, opening 23 Side wall 24 Bottom surface 25 Titanium-tantalum barrier layer thin film 26 Top surface 27 Lower titanium thin film, thin film 29 Upper tantalum thin film, thin film 31 Conductive thin film 32 Thickness 33 Side wall, seed layer thin film 35 Conductive Conductive wire 37 upper surface 39 conductive wire 40 region 125 barrier layer thin film, titanium-tantalum layer, titanium-tantalum thin film, region 225 titanium-tantalum thin film, barrier layer thin film

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI H01L 21/3205 H01L 21/88 R 21/768 21/90 C (72) Inventor Minseok O United States 32836 Florida, Orlando, Linderhurst Drive 7524 (72) Inventor Pradip Kumar Roy United States 32819 Florida, Orlando, Hidden Ivy Court 7706 (72) Inventor Sid Hazasen United States 32835 Florida, Orlando, Conroy Road 6373-Apartment 1905 (56) Reference Flat 11-265890 (JP, A) US Patent 5891513 (US, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/285 H01L 21/768 H01L 21/3205 C23C 14/14 C23C 16/06

Claims (37)

(57) [Claims] 1. A) preparing a substrate having a substrate surface; b) depositing a titanium-tantalum thin film on the substrate surface, said thin film having a gradient of titanium concentration therein, the titanium concentration being the substrate surface. A process of depositing a thin film on a substrate that includes a step of maximizing in a portion of the thin film closest to and decreasing along a direction extending perpendicularly from the substrate surface. 2. The process of claim 1, wherein step b) comprises providing a sputtering target in a sputtering apparatus, the sputtering target being formed of a uniform composition containing titanium and tantalum. 3. Step b) supplies an electric current to the sputtering target, whereby the titanium-tantalum thin film is continuously sputtered, i: sputtering the lower part of the titanium-tantalum thin film on the substrate surface, the lower part being the first part. Sputtering a central portion of the titanium-tantalum thin film onto the lower portion, the central portion having a second titanium weight percentage less than the first titanium weight percentage, and iii. The process of claim 2 wherein a top portion of the titanium-tantalum thin film is sputtered onto the top portion, the top portion having a third titanium weight percentage less than the second titanium weight percentage. 4. Step b) prepares a titanium sputtering target in the sputtering apparatus and a tantalum sputtering target in the sputtering apparatus, each sputtering target being individually restricted and suitable for sputtering material onto a substrate. The process of claim 1. 5. Step b) includes supplying an electric current to the titanium sputtering target and supplying an electric current to the tantalum sputtering target, whereby a titanium-tantalum thin film is continuously sputtered, i. -Sputtering a lower portion of the tantalum thin film, the lower portion having a first titanium weight percentage; ii Sputtering a central portion of the titanium-tantalum thin film on the lower portion, the central portion being less than the first titanium weight percentage. 5. Having a second titanium weight percentage; iii Sputtering an upper portion of the titanium-tantalum thin film on the central portion, the upper portion having a third titanium weight percentage less than the second titanium weight percentage. process. 6. An ampere of an electric current and a further electric current, a respective voltage level of a titanium sputtering target and a tantalum sputtering target, and a power level of each titanium sputtering target and a tantalum sputtering target.
6. The process of claim 5, comprising changing one during step b). 7. The step b) comprises chemical vapor deposition.
The described process. 8. The process of claim 1, wherein step b) comprises physical vapor deposition. 9. A semiconductor substrate having a dielectric thin film formed on a) is prepared, the dielectric thin film including a dielectric surface,
Having an opening formed therein, the opening including sidewalls and a bottom, b) depositing a titanium-tantalum barrier layer on the dielectric surface and the sidewalls and the bottom, but not filling the opening; c). Depositing a conductive film on the barrier layer and to fill the opening and d) removing portions of the barrier layer and the conductive film on the plane formed by the dielectric surface, and removing other parts of the barrier layer and the conductive film. A portion of the titanium-tantalum barrier layer having a gradient of titanium concentration therein, the titanium concentration being a barrier closest to a boundary formed between the titanium-tantalum barrier layer and the dielectric thin film. A process of forming a semiconductor device, which is maximum in a portion of a layer and decreases in a direction extending vertically from a boundary. 10. The process of claim 9, wherein step a) includes forming the dielectric thin film by one of CVD and spin-on techniques. 11. The process of claim 9 wherein the opening is a dual damascene trench structure and step d) comprises chemical mechanical polishing. 12. The titanium-tantalum barrier layer has a titanium concentration gradient therein, the titanium concentration being maximum in the portion of the barrier layer closest to the boundary formed between the titanium-tantalum barrier layer and the dielectric thin film. 10. Along the direction perpendicularly extending from the boundary, step b) comprises depositing the titanium-tantalum barrier layer using one of chemical vapor deposition and physical vapor deposition. Process. 13. The step b) is a step of i) preparing a sputtering target in a sputtering apparatus, and the sputtering target is formed with a uniform composition containing titanium and tantalum; ii) disposing a semiconductor substrate in the sputtering apparatus. And iii) supplying an electric current to the sputtering target,
10. The process of claim 9, wherein the titanium-tantalum thin film is sputtered, the titanium-tantalum thin film comprising the step of forming a titanium-tantalum barrier layer. 14. The step b) is a step of i) disposing a semiconductor substrate in a sputtering apparatus; ii) preparing a titanium sputtering target in the sputtering apparatus and a tantalum sputtering target in the sputtering apparatus, each sputtering target being a semiconductor substrate. A step suitable for sputtering material on; and iii) supplying an electric current to the titanium sputtering target and further supplying an electric current to the tantalum sputtering target, whereby a titanium-tantalum thin film is sputtered, and the titanium-tantalum thin film is titanium. 10. The process of claim 9 including the step of forming a tantalum barrier layer. 15. The process of claim 13, wherein step b) further comprises the step of iv) heating the titanium-tantalum barrier layer. 16. Step iii) supplies an electric current to a sputtering target, whereby a titanium-tantalum thin film is continuously sputtered, and A. A lower portion of the titanium-tantalum thin film is sputtered onto the dielectric surface, sidewalls and bottom, the lower portion having a first weight percent titanium; A central portion of the titanium-tantalum thin film is sputtered on the lower portion, the central portion having a second titanium weight percentage that is less than the first titanium weight percentage, and C.I. The upper portion of the titanium-tantalum thin film is sputtered onto the central portion, the upper portion having a third weight percentage less than the second titanium weight percentage.
The process described in 3. 17. The process of claim 9, wherein step c) comprises depositing one of a nickel thin film and an aluminum thin film. 18. The process of claim 9, wherein step c) comprises depositing a copper thin film. 19. The method according to claim 9, wherein an electrolytic plating seed layer is formed on the titanium-tantalum barrier layer but the opening is not filled, and step c) further includes step b1) of forming a copper thin film by electrolytic deposition. process. 20. a) providing a semiconductor substrate having a dielectric thin film formed thereon; b) depositing a titanium-tantalum barrier layer on the dielectric surface of the dielectric thin film; c) titanium- Depositing one conductive thin film of nickel and aluminum on the tantalum barrier layer, thereby forming a synthetic thin film of the titanium-tantalum barrier layer and the conductive thin film; d) removing the synthetic thin film and thereby the synthetic thin film Forming a semiconductor device and forming an interconnection pattern thereof. 21. The method further comprises the step b1) of forming an electroplating seed layer on the titanium-tantalum barrier layer, and step c).
21. The process of claim 20, wherein the comprises electroplating and the synthetic thin film further comprises an electroplated sheet layer. 22. The process of claim 20, wherein step c) comprises forming a titanium film and then forming a tantalum film on the titanium film. 23. Step b) comprises i) preparing a sputtering target in a sputtering apparatus, the sputtering target being formed of a uniform composition containing titanium and tantalum; ii) disposing a semiconductor substrate in the sputtering apparatus; and iii) supplying an electric current to the sputtering target,
Thereby sputtering a titanium-tantalum thin film on the dielectric surface, the titanium-tantalum thin film forming a titanium-tantalum barrier layer, the titanium-tantalum barrier layer having a titanium concentration gradient therein, 21. The process of claim 20, wherein the concentration decreases along a direction extending vertically from the dielectric surface. 24. A titanium-tantalum thin film formed according to the process of claim 3. 25. A dielectric layer having an opening formed therein, a top surface of the dielectric layer, an exposed surface including a sidewall and a bottom of the opening, and a titanium-tantalum barrier formed on the exposed surface. A layer, the titanium-tantalum barrier layer having a gradient of titanium concentration therein, the titanium concentration being
A semiconductor device that decreases in a direction extending vertically from the exposed surface. 26. The semiconductor device according to claim 25, further comprising a conductive thin film formed on the barrier layer. 27. The semiconductor device according to claim 26, wherein the conductive thin film contains copper. 28. The semiconductor device of claim 26, further comprising a seed layer thin film sandwiched between the titanium-tantalum barrier layer and the conductive thin film. 29. The semiconductor device of claim 26, wherein the conductive thin film comprises one of nickel and aluminum. 30. The semiconductor device of claim 25, wherein the titanium concentration is maximum at or near the exposed surface. 31. The semiconductor device of claim 25, wherein the titanium-tantalum barrier layer comprises a thin film having a tantalum concentration gradient therein, the tantalum concentration increasing along a direction extending perpendicularly from the exposed surface. 32. The semiconductor device of claim 25, wherein the tantalum concentration is minimal at or near the exposed surface. 33. The semiconductor of claim 25, wherein the titanium-tantalum barrier layer comprises a thin film that is relatively titanium-rich adjacent the exposed surface and relatively titanium-deficient adjacent the upper surface of the thin film. device. 34. Formed within a damascene opening formed in a dielectric thin film, the dielectric thin film having a top surface, the damascene opening including sidewalls and bottom, and the damascene structure formed on the sidewall and bottom. A conductive layer is formed on the barrier layer, the damascene structure includes a top surface and a flat top surface, and the titanium-tantalum barrier layer is A damascene structure having a tip surface bounding a sidewall and a bottom surface and a gradient of titanium concentration in the layer, where the titanium concentration has a maximum at or near the boundary and decreases in a direction extending vertically from the boundary. 35. The damascene structure according to claim 34, further comprising a seed layer thin film sandwiched between the titanium-tantalum barrier layer and the conductive layer. 36. The damascene structure according to claim 34, wherein the conductive layer comprises copper. 37. The damascene structure according to claim 34, wherein the conductive layer comprises one of nickel and aluminum.