KR19990012246A - Semiconductor device with metal barrier film by atomic layer deposition method and method for manufacturing same - Google Patents

Abstract

Provided are a semiconductor device capable of completely blocking diffusion of oxygen by embedding a barrier film made of a ternary compound into a contact hole, and a method of manufacturing the same. A semiconductor device comprising a material layer filling a contact hole on a semiconductor substrate, and a capacitor in which a lower electrode, a high dielectric film, and a lower electrode are sequentially stacked on the material layer, wherein the material layer is buried in the contact hole. It consists of a ternary compound formed by this atomic layer deposition method, and includes the barrier film provided in contact with the lower electrode. The ternary compound constituting the barrier film is made of TiSiN, TiBN, WSiN, or WBN. The barrier layer made of TiSiN has a structure in which a TiN atomic layer and an Si atomic layer are alternately stacked alternately, or a TiN atomic layer and a pyrolytically deposited Si ₃ N ₄ layer are alternately repeatedly stacked.

Description

Semiconductor device provided with metal barrier film by atomic layer deposition method and manufacturing method therefor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a barrier metal layer of a semiconductor device having a metal barrier layer prevented from oxidation and a method of manufacturing the same.

As the size of devices decreases in order to integrate semiconductor devices, high dielectric materials having high dielectric constants have been developed to obtain large capacitances in a small area. For example, in the case of BST (BaSrTiO ₃ ) having a perovskite crystal structure, the dielectric constant of the BST (BaSrTiO ₃ ) film is different from that of a silicon nitride film, a silicon nitride oxide film, or a tantalum oxide (Ta ₂ O ₅ ) film. Hundreds to about 1000 substances. In the case of using such a BST, even if the thickness of the film is 500 kPa or more, the dielectric film can be thinned with an equivalent oxide thickness of 10 kPa or less. The electrode for BST does not oxidize, such as platinum (Pt), or is oxidized like ruthenium (Ru) or iridium (Ir) to form ruthenium oxide (RuO ₂ ) or iridium oxide (IrO ₂ ). Use electrodes with properties.

In order to obtain excellent capacitance and leakage current characteristics in the BST high dielectric film deposited by sputtering, heat treatment at high temperature is required after the deposition of BST. In this case, it is necessary to form a diffusion barrier layer to prevent oxidation of the ohmic layer and the storage poly by the diffusion of oxygen. The diffusion barrier layer is interposed between the storage poly and the lower electrode.

In the current metal contact structure, a TiN film is used as the barrier metal layer. However, in the case of TiN, the TiN film is oxidized at 450 ° C. or higher, and Pt and Si diffuse into the interior, and as a result, the TiN film cannot serve as a diffusion barrier. When TiN is oxidized, there is a problem that TiO _{2, which} is an insulator, is generated. The diffusion of Pt and Si is known to be due to the columnar crystal structure of TiN. Therefore, it is necessary to suppress the diffusion of oxygen by making the membrane structure an amorphous structure having no grain boundary serving as a diffusion path. From these needs, studies on ternary compounds containing high melting point metals are being actively conducted.

The sputtering process is generally used at the time of depositing the barrier metal film which consists of said tertiary compound. The capacitor having the barrier metal film formed by sputtering in this manner has a structure as shown in FIG.

Referring to FIG. 1, an insulating layer 20 having contact holes is formed on a semiconductor substrate 10. A contact plug 30 made of polysilicon is formed in the contact hole. On the top of the structure, the titanium silicide film 40, the barrier film 50, the lower electrode 60, the dielectric film 70 made of BST, and the upper electrode 80, which are ohmic layers, protrude from the surface of the structure sequentially. Is formed.

However, such a structure has a problem in that oxygen is diffused from the top to the bottom along the lower electrode and the barrier layer when the BST is post-processed. In addition, there is a problem in that oxygen is diffused through the side due to the absence of a film acting as a protective film on the side of the electrode.

In order to suppress the lateral oxygen diffusion, a structure as shown in FIG. 2 is currently being actively studied. Referring to FIG. 2, an oxygen diffusion preventing spacer 90 made of oxide or nitride is provided on a side surface of the structure protruding from the substrate surface as shown in FIG. 1 to prevent side oxygen diffusion.

However, the structure shown in FIG. 2 has a problem that the possibility of mass production is low because it is too complicated and there is no process margin in the photolithography process.

An object of the present invention is to provide a semiconductor device capable of completely blocking the diffusion of oxygen by embedding a barrier film made of a ternary compound in a contact hole, and a manufacturing method thereof.

1 is a cross-sectional view showing a capacitor having a conventional high dielectric film.

Figure 2 is a cross-sectional view showing a high-k dielectric capacitor with a conventional spacer.

3 is a cross-sectional view of a capacitor provided with a ternary compound barrier film of the present invention.

4 to 11 are cross-sectional views illustrating barrier films according to first to eighth embodiments of the present invention, respectively.

According to an aspect of the present invention, there is provided a semiconductor device including a material layer filling a contact hole on a semiconductor substrate and a capacitor in which a lower electrode, a high dielectric film, and a lower electrode are sequentially stacked on the material layer. The material layer filling the contact hole may be formed of a ternary compound formed by an atomic layer deposition method, and may include a barrier film provided under the lower electrode. A polysilicon film and an ohmic layer sequentially formed below the barrier film may be further included.

According to preferred embodiments of the present invention, the ternary compound constituting the barrier layer is made of TiSiN, TiBN, WSiN, or WBN.

The barrier layer made of TiSiN has a structure in which a TiN atomic layer and an Si atomic layer are alternately stacked alternately, or a TiN atomic layer and a pyrolytically deposited Si ₃ N ₄ layer are alternately repeatedly stacked.

The barrier film made of TiBN has a structure in which a TiN atomic layer and a B layer deposited by thermal decomposition are alternately stacked or alternately stacked in a TiN atomic layer and a BN atomic layer.

The barrier film made of WSiN has a structure in which a WN atomic layer and a pyrolytically deposited Si layer are alternately stacked, or a structure in which a WN atomic layer and a Si ₃ N ₄ atomic layer are alternately stacked.

The barrier film made of the WBN has a structure in which a WN atomic layer and a B layer deposited by pyrolysis are alternately stacked, or a structure in which a WN atomic layer and a BN atomic layer are alternately stacked.

A method of manufacturing a semiconductor device having a barrier film made of the ternary compound includes filling a contact hole on a semiconductor substrate with a conductive material layer and then performing an etching process to form a conductive material film only at the bottom of the contact hole. After forming an ohmic layer on the conductive material film, a barrier film made of a ternary compound is formed on the ohmic layer by atomic layer deposition so that the contact hole is filled. The ternary compound constituting the barrier film is made of TiSiN, TiBN, WSiN, or WBN. A capacitor is formed by sequentially forming a lower electrode, a high dielectric film, and an upper electrode on the barrier film.

According to preferred embodiments of the present invention, the forming of the barrier layer made of TiSiN may be performed by using a TiN atomic layer deposition process using TiCl ₄ and NH ₃ as precursors and pyrolytic deposition of SiH ₄ or Si ₂ H ₆ . Alternating Si deposition process alternately, or TiN atomic layer deposition process using TiCl ₄ and NH ₃ as precursor and Si ₃ N ₄ atomic layer deposition process using SiCl ₂ H ₂ and NH ₃ as precursor Alternately proceed with.

The forming of the barrier film made of TiBN may be performed by alternately repeating a TiN atomic layer deposition process using TiCl ₄ and NH ₃ as precursors and a B deposition process using pyrolysis of B ₂ H ₆ , or TiCl _4. proceeds to the NH ₃ to repeat the TiN atomic layer deposition process and BCl _3, H _2, NH _3, and used as a precursor to an atomic layer deposition process BN alternately used as a precursor.

The forming of the barrier film made of WSiN may be performed by alternately repeating a WN atomic layer deposition process using WF ₆ and NH ₃ as precursors and a Si deposition process using pyrolysis of SiH ₄ or Si ₂ H ₆ . Alternatively, the WN atomic layer deposition process using WF ₆ and NH ₃ as precursors and the Si ₃ N ₄ atomic layer deposition process using SiCl ₂ H ₂ and NH ₃ as precursors are alternately repeated.

The forming of the barrier film made of WBN may be performed by alternately repeating a WN atomic layer deposition process using WF ₆ and NH ₃ as precursors and a B deposition process using pyrolysis of B ₂ H ₆ , or WF _6. proceeds to the NH ₃ to repeat the WN an atomic layer deposition process and the BCl _3, H _2, NH _3, and used as a precursor to an atomic layer deposition process BN alternately used as a precursor.

Hereinafter will be described the operation and operation principle of the present invention.

The ternary material of the ABN structure of the present invention forms a thermally and chemically stable phase while the AN compound increases the conductivity of the film and the BN compound of the amorphous structure blocks the diffusion path of impurities. For example, in the case of TiSiN, TiN guarantees conductivity of the film, and an amorphous silicon nitride film (Si ₃ N ₄ ) blocks the diffusion path of impurities, thereby showing excellent diffusion prevention characteristics.

In spite of the excellent properties described above, such ternary materials cannot be embedded in the contact holes due to poor step coating properties. Accordingly, in the present invention, a ternary metal film having a complex composition is embedded in the contact hole by using atomic layer deposition (ALD).

ALD is a deposition method that uses a chemical reaction like chemical vapor deposition (CVD), but differs from CVD in that each gas flows in pulses one by one without mixing in the chamber. For example, in the case of using A and B gases, only A flows first. At this time, A gas molecules are chemisorbed onto the substrate. A gas remaining in the chamber is purged with an inert gas such as argon or nitrogen. Then, when only B gas flows, the reaction between A and B occurs only on the surface of the chemisorbed A gas, and a thin film of an atomic layer is deposited. For this reason, even if the surface has any morphology, 100% step coverage is always obtained. By purging the B gas remaining in the chamber and the by-products of the A and B reactions and flowing A gas again, the thickness of the thin film can be controlled in atomic layer units according to the number of cycles to be repeated.

In the case of CVD, since the composition of the thin film is determined by the thermodynamic reaction of the reaction gases, the composition control of the thin film of a complex composition such as a three-way barrier metal film is not easy. On the other hand, ALD can deposit thin films with the composition of ABC by alternately depositing the desired materials in the thickness of the atomic layer, for example, by alternately depositing the AB film and the AC film, thus enabling the deposition of thin films with more complicated compositions as well as ternary systems. Do.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 3, an insulating layer 110 including contact holes and made of SiO ₂ is provided on the semiconductor substrate 100. After embedding the polysilicon into the contact hole, a wet etching combined with wet etching or chemical mechanical polishing is performed to leave the polysilicon layer 120 only at the bottom of the contact hole. In order to form an ohmic layer on the polysilicon layer, titanium (Ti) is deposited by sputtering or PECVD (Plsma Enhanced Chemical Vapor Deposition) to form a titanium silicide (TiSix) layer 130. A metal layer made of a ternary compound is deposited on the resultant structure by ALD to fill a contact hole, and then a portion of the metal layer deposited on the outside of the contact hole is etched back by wet etching or chemical mechanical polishing to be formed only inside the contact hole. An ALD barrier layer 140 is formed. As shown in FIG. 3, the ALD barrier film of the present invention can have a larger thickness than in the prior art. A capacitor including a lower electrode 150, for example, a high dielectric film 160 made of BST and an upper electrode 170 is formed on the resulting structure.

As can be seen from the above description, the capacitor of the present invention is an ideal structure capable of maximizing the thickness of the barrier film and completely eliminating side oxygen diffusion. In addition, since the metal layer is deposited in the contact hole using the ALD method, a metal made of a ternary compound having a complex composition can be embedded in the contact hole with good step coverage. Further, according to the ALD method, since the desired materials can be alternately deposited to an atomic layer thickness, not only a ternary compound but also a thin film of a more complicated composition is possible.

Hereinafter, a method of forming the ALD barrier film according to the present invention will be described with reference to specific examples.

Example 1

As shown in FIG. 4, ALD-TiN and ALD-TiSiN using Si pyrolysis deposition are formed. In ALD-TiN, TiCl ₄ and NH ₃ are used as precursors, and Si deposition uses pyrolysis of SiH ₄ and Si ₂ H ₆ . Argon (Ar) is used as a carrier gas. Therefore, the gas flow flowing into the deposition chamber when forming the barrier film of FIG. 4 cycles in the order of TiCl ₄ → Ar → NH ₃ → Ar → SiH ₄ (Si ₂ H ₆ ) → Ar.

Example 2

As shown in FIG. 5, ALD-TiNN using ALD-TiN and ALD-Si ₃ N ₄ is formed. TiCl ₄ and NH ₃ are used as precursors in ALD-TiN and SiCl ₂ H ₂ and NH ₃ are used as precursors for ALD-Si ₃ N ₄ deposition. Therefore, when forming the barrier film of FIG. 5, the gas flow cycles in the order of TiCl ₄ → Ar → NH ₃ → Ar → SiCl ₂ H ₂ → Ar → NH ₃ → Ar.

Example 3

As shown in FIG. 6, ALD-TiN and ALD-TiBN are formed by B ₂ H ₆ pyrolysis. The ternary compound TiBN will show better diffusion barrier properties than conventional TiB ₂ . In the formation of ALD-TiN, TiCl ₄ and NH ₃ are used as precursors and deposition of B is achieved by pyrolyzing B ₂ H ₆ . Therefore, when forming the barrier film of FIG. 6, the gas flow cycles in the order of TiCl ₄ → Ar → NH ₃ → Ar → B ₂ H ₆ → Ar.

Example 4

As shown in FIG. 7, ALD-TiBN is formed using ALD-TiN and ALD-BN. In the formation of ALD-TiN, TiCl ₄ and NH ₃ are used as precursors, and ALD-BN is deposited using BCl ₃ , H ₂ and NH ₃ . Therefore, the gas flow used in this embodiment is cycled in the order of TiCl ₄ → Ar → NH ₃ → Ar → BCl ₃ → Ar → H ₂ + NH ₃ → Ar.

Example 5

As shown in FIG. 8, ALD-WN and ALD-WSiN using Si pyrolysis are formed. In the formation of ALD-WN, WF ₆ and NH ₃ are used as precursors, and Si deposition uses SiH ₄ and Si ₂ H ₆ pyrolysis. Therefore, the gas flow in the case of forming the barrier film shown in FIG. 8 cycles in the order of WF ₆ → Ar → NH ₃ → Ar → SiH ₄ (Si ₂ H ₆ ) → Ar.

Example 6

As shown in FIG. 9, ALD-Wi and ALD-Si ₃ N ₄ are used to form ALD-WSiN. In the formation of ALD-WN, WF ₆ and NH ₃ are used as precursors, and ALD-Si ₃ N ₄ uses SiCl ₂ H ₂ and NH ₃ as precursors. Therefore, the gas flow in the case of forming the barrier film shown in FIG. 9 cycles in the order of WF ₆ → Ar → NH ₃ → Ar → SiCl ₂ H ₂ → Ar → NH ₃ → Ar.

Example 7

As shown in FIG. 10, ALD-WN and ALD-WBN using B pyrolysis are formed. The formation of ALD-WN uses WF ₆ and NH ₃ as precursors, and the deposition of B uses pyrolysis of B ₂ H ₆ . Therefore, the gas flow in the case of forming the barrier film shown in FIG. 10 cycles in the order of WF ₆ → Ar → NH ₃ → Ar → B ₂ H ₆ → Ar.

Example 8

As shown in FIG. 11, ALD-WBN is formed using ALD-WN and ALD-BN. In the formation of ALD-WN, WF ₆ and NH ₃ are used as precursors, and ALD-BN deposition is performed using BCl ₃ , H ₂ , and NH ₃ . Therefore, the gas flow in the case of forming the barrier film of the present embodiment is cycled in the order of WF ₆ → Ar → NH ₃ → Ar → BCl ₃ → Ar → NH ₃ + H ₂ → Ar.

According to the invention,

First, it is possible to prevent the diffusion of oxygen during the post-treatment of the high dielectric film,

Second, even if the barrier layer is thick, the area of the dielectric layer does not decrease.

Third, there is an advantage in that the barrier film having a complex composition of three or more members can be deposited to have excellent step coverage.

Claims (21)

A semiconductor device comprising a material layer filling a contact hole on a semiconductor substrate, and a capacitor having a lower electrode, a high dielectric film, and a lower electrode sequentially stacked on the material layer. The semiconductor device with a ternary compound barrier film, wherein the material layer filling the contact hole comprises a ternary compound formed by an atomic layer deposition method and is provided in contact with the lower electrode. The semiconductor device with a ternary compound barrier film according to claim 1, wherein the ternary compound constituting the barrier film is any one selected from the group consisting of TiSiN, TiBN, WSiN, and WBN. The semiconductor device according to claim 1, wherein the material layer filling the contact hole further comprises a polysilicon film and an ohmic layer sequentially formed below the barrier film. 3. The semiconductor device according to claim 2, wherein the barrier film made of TiSiN has a structure in which a TiN atomic layer and an Si atomic layer are alternately stacked alternately. 3. The semiconductor device according to claim 2, wherein the barrier film made of TiSiN has a structure in which a TiN atomic layer and a pyrolytically deposited Si ₃ N ₄ layer are alternately stacked alternately. 3. The semiconductor device according to claim 2, wherein the barrier film made of TiBN has a structure in which a TiN atomic layer and a B layer deposited by thermal decomposition are alternately laminated. 3. The semiconductor device according to claim 2, wherein the barrier film made of TiBN has a structure in which a TiN atomic layer and a BN atomic layer are alternately stacked alternately. 3. The semiconductor device according to claim 2, wherein the barrier film made of WSiN has a structure in which a WN atomic layer and a pyrolytically deposited Si layer are alternately stacked alternately. 3. The semiconductor device according to claim 2, wherein the barrier film made of WSiN has a structure in which a WN atomic layer and an Si ₃ N ₄ atomic layer are alternately stacked alternately. 3. The semiconductor device according to claim 2, wherein the barrier film made of WBN has a structure in which a WN atomic layer and a B layer deposited by thermal decomposition are alternately laminated. 3. The semiconductor device according to claim 2, wherein the barrier film made of WBN has a structure in which a WN atomic layer and a BN atomic layer are alternately stacked alternately. Filling a contact hole on the semiconductor substrate with a conductive material layer and then performing an etching process to form a conductive material film only at the bottom of the contact hole; Forming an ohmic layer on the conductive material film; Forming a barrier film made of a ternary compound on the ohmic layer by using an atomic layer deposition method so as to fill the contact hole; And sequentially forming a lower electrode, a high dielectric film, and an upper electrode on the barrier film. The method of manufacturing a semiconductor device with a ternary compound barrier film according to claim 12, wherein the ternary compound constituting the barrier film is any one selected from the group consisting of TiSiN, TiBN, WSiN, and WBN. The method of claim 13, wherein the forming of the barrier layer formed of TiSiN comprises using a TiN atomic layer deposition process using TiCl ₄ and NH ₃ as precursors and a Si deposition process using pyrolytic deposition of SiH ₄ or Si ₂ H ₆ . A method of manufacturing a semiconductor device having a three-way compound barrier film, which is alternately repeated. The method of claim 13, wherein the forming of the barrier layer formed of TiSiN comprises: a TiN atomic layer deposition process using TiCl ₄ and NH ₃ as precursors and Si ₃ N using SiCl ₂ H ₂ and NH ₃ as precursors. _A method of manufacturing a semiconductor device having a three-way compound barrier film, characterized in that the _four atomic layer deposition steps are alternately repeated. The method of claim 13, wherein the forming of the barrier film made of TiBN is performed by alternately repeating a TiN atomic layer deposition process using TiCl ₄ and NH ₃ as precursors and a B deposition process using pyrolysis of B ₂ H ₆ . A method of manufacturing a semiconductor device provided with a three-way compound barrier film, characterized in that it proceeds. The method of claim 13, wherein the forming of the barrier film made of TiBN comprises: a TiN atomic layer deposition process using TiCl ₄ and NH ₃ as precursors and a BN using BCl ₃ , H ₂ , and NH ₃ as precursors. A method of manufacturing a semiconductor device with a three-way compound barrier film, characterized in that the atomic layer deposition step is repeated alternately. The method of claim 13, wherein the forming of the barrier layer formed of WSiN is performed by alternating a WN atomic layer deposition process using WF ₆ and NH ₃ as precursors and a Si deposition process using pyrolysis of SiH ₄ or Si ₂ H ₆ . A method of manufacturing a semiconductor device with a three-way compound barrier film, characterized in that the process proceeds repeatedly. The method of claim 13, wherein the forming of the barrier layer formed of WSiN comprises: a WN atomic layer deposition process using WF ₆ and NH ₃ as precursors and Si ₃ N using SiCl ₂ H ₂ and NH ₃ as precursors; _A method of manufacturing a semiconductor device having a three-way compound barrier film, characterized in that the _four atomic layer deposition steps are alternately repeated. The method of claim 13, wherein the forming of the barrier film made of WBN is performed by alternately repeating a WN atomic layer deposition process using WF ₆ and NH ₃ as precursors and a B deposition process using pyrolysis of B ₂ H ₆ . A method of manufacturing a semiconductor device provided with a three-way compound barrier film, characterized in that it proceeds. The method of claim 13, wherein the forming of the barrier film made of WBN comprises: a WN atomic layer deposition process using WF ₆ and NH ₃ as precursors, and a BN using BCl ₃ , H ₂ , and NH ₃ as precursors. A method of manufacturing a semiconductor device with a three-way compound barrier film, characterized in that the atomic layer deposition step is repeated alternately.