KR20220153483A - Semiconductor Device for DRAM and Method of Manufacturing the Same - Google Patents

Abstract

The present invention relates to a semiconductor element for a DRAM and a manufacturing method thereof which can prevent deterioration of a contact resistor that occurs between a landing pad and a lower electrode of a capacitor when a lower electrode of a capacitor for a DRAM is manufactured by using a rare metal having a large work function by an atomic layer deposition (ALD) method using an oxygen-based reactive gas. According to the present invention, the semiconductor element for a DRAM with a landing pad connected to a lower electrode of a capacitor comprises an oxidization preventing film made of a metal having a conductive feature in case of oxidization between the landing pad and the lower electrode.

Description

Semiconductor Device for DRAM and Method of Manufacturing the Same}

The present invention relates to a semiconductor device for DRAM and a method for manufacturing the same, and more specifically, to a lower electrode of a capacitor for DRAM using a rare metal having a high work function by an atomic layer deposition (ALD) method using an oxygen-based reactive gas. It relates to a semiconductor device for DRAM capable of preventing deterioration of contact resistance occurring between a landing pad and a lower electrode of a capacitor when manufacturing a semiconductor device and a manufacturing method thereof.

A semiconductor device such as a dynamic random access memory (DRAM) includes a MOS transistor, a capacitor, and wiring. The MOS transistor has a source region and a drain region. The capacitor may be electrically connected to the source region. The wiring, for example, a bit line, may be electrically connected to the drain region.

The capacitor and the bit line are connected to the source region and the drain region through respective contact plugs. In this case, each contact plug may not be directly connected, but may be connected in contact with landing pads located on the source region and the drain region.

In addition, in a DRAM device composed of a transistor and a capacitor, a sensing margin or reliability problem arises due to the limitation of the capacitance of the capacitor according to the miniaturization of the process to increase the degree of integration, that is, the reduction of the design rule. Accordingly, a technique for increasing the capacitance of a capacitor per unit area is required. As known, capacitance is proportional to the dielectric constant of the dielectric film, proportional to the opposing area between the two electrodes, and inversely proportional to the physical thickness of the dielectric film.

So far, in order to meet the capacitance required by semiconductor devices, devices have been manufactured by using a dielectric film having a high dielectric constant and maximizing the opposing area. However, as process miniaturization progresses, it is difficult to increase the opposing area, and the search for a dielectric film having a new high dielectric constant has reached a limit. Therefore, a new method is to obtain a capacitance required by a device by reducing the physical thickness of the dielectric film in the current dielectric film.

However, in the case of using a conventional titanium nitride (TiN) film as the upper and lower electrodes of a capacitor, when the thickness of the dielectric film is reduced, leakage current characteristics deteriorate and the characteristics of the device are deteriorated, so that it cannot be used. The leakage current between the dielectric film and the counter electrode is related to the work function of the counter electrode, and the leakage current decreases as the work function increases. Therefore, a process design for forming a thin dielectric film while using upper and lower electrodes having a large work function is required, and a technology that satisfies the capacitance required by a semiconductor device through this process is required.

In the case of TiN, it changes according to the ratio of titanium and nitrogen, but has a work function of 4.3 to 4.6 eV. In order to meet the required level of leakage current in a thin dielectric film thickness, noble metals such as Ru, Ir, and Pt (>4.7 eV) having a high work function are required. In order to use a rare metal as an upper electrode or a lower electrode, it is necessary to deposit a uniform thickness in a high aspect ratio structure.

As this deposition method, chemical vapor deposition (CVD) or atomic layer deposition (ALD) is being studied. Among them, the CVD method cannot obtain the desired deposition uniformity in microscopic design devices of 15 nm or less, so the ALD method is the most suitable technology for forming the lower electrode of the capacitor. The ALD method is possible in a low-temperature process using surface adsorption, and thickness uniformity can be obtained at a high level while depositing by repeating adsorption and surface reaction.

In the case of deposition using the ALD method, a precursor and a reactive gas serving as a source of rare metals are required. Precursors are selected according to adsorption and bonding strength, and ammonia-based and oxygen-based reactive gases are recommended. The results of research on reactive gases show that the use of oxygen or oxygen radicals is the most desirable reactive gas for controlling reaction, surface uniformity, and surface roughness, and using oxygen or oxygen radicals is the most suitable it is made

However, when the lower electrode of a capacitor is formed by the ALD method using an oxygen-based reactive gas, the surface of the metal landing pad formed to connect the lower electrode and the semiconductor substrate is oxidized to form a metal oxide film on the contact area. According to the insulation, a phenomenon that prevents operation as a semiconductor device occurs.

Therefore, if the metal oxide film that increases the contact resistance is not overcome between the landing pad and the lower electrode of the capacitor, the process of forming the lower electrode of the capacitor with rare metals such as Ru or Ir using the ALD method cannot be used. .

Korean Patent Registration No. 10-2171267 (Patent Document 1) includes a substrate having an active region; a conductive line structure formed on the substrate and including an insulating spacer structure on each sidewall; an insulating pattern formed on an upper portion of the conductive line structure and an upper portion of the insulating spacer structure; a conductive layer for forming a contact connected to the active region and formed between the pair of conductive line structures; a conductive layer for forming a landing pad in contact with an upper surface of the conductive layer for forming a contact; Disclosed is a semiconductor device including a landing pad connected to an upper surface of the conductive layer for forming the landing pad and vertically overlapping one of the conductive line structures.

The semiconductor device of Patent Document 1 includes a contact plug and a landing pad connected to the active region of the substrate to electrically connect the active region of the substrate and the lower electrode of the capacitor. The landing pad vertically overlaps the conductive line structure and covers the conductive line structure and the second insulating pattern. The landing pad is electrically connected to the contact plug. A metal silicide layer may be formed between the contact plug and the landing pad. A lower electrode of the capacitor is connected to the landing pad.

However, Patent Document 1 discloses a technique of forming a capacitor lower electrode connected to the landing pad with an atomic layer deposition (ALD) method for deposition uniformity when forming a rare metal having a large work function, There is not.

: Korea Patent Registration No. 10-2171267

Therefore, the present invention has been proposed to solve the above problems of the prior art, and its object is to use a rare metal having a large work function as an atomic layer deposition (ALD) method using an oxygen-based reactive gas. An object of the present invention is to provide a semiconductor device for DRAM capable of preventing deterioration of contact resistance occurring between a landing pad and a lower electrode of a capacitor when manufacturing a lower electrode of a DRAM capacitor, and a manufacturing method thereof.

Another object of the present invention is to provide a rare metal ALD process using an oxygen-based reactive gas by forming an oxide film with a metal that is conductive even when oxidation occurs on the uppermost surface layer of the landing pad in contact with the lower electrode of the capacitor. An object of the present invention is to provide a semiconductor device for DRAM and a method for manufacturing the same, in which a conductive metal oxide film is formed on top of the oxidation prevention film to prevent deterioration of contact resistance.

Another object of the present invention is to reduce the contact resistance between the lower electrode of the capacitor and the landing pad connecting the semiconductor substrate to secure a timing margin when reading and writing the DRAM device, thereby improving the performance of the DRAM device. It is to provide a semiconductor device for DRAM capable of improving performance and reliability and a manufacturing method thereof.

In order to achieve the above object, a semiconductor device for DRAM having a landing pad connected to a lower electrode of a capacitor according to an embodiment of the present invention is formed of a metal having conductivity when oxidized between the landing pad and the lower electrode. It is characterized in that it contains an antioxidant film.

The lower electrode and the anti-oxidation layer are each made of a noble metal, and the noble metal may be Ru or Ir. In addition, the anti-oxidation layer may be deposited using sputtering or chemical vapor deposition.

Moreover, the landing pad contacts the upper end of the contact plug connected to the active region of the substrate, and may be made of one or a combination of Ti, TiN, W, and Mo.

In this case, the lower electrode may be formed by an atomic layer deposition (ALD) method of a rare metal using an oxygen-based reactive gas.

In addition, when the lower electrode is formed using an oxygen-based reactive gas, the anti-oxidation layer may be formed to a thickness capable of preventing oxidation of the landing pad by an oxidation reaction with the reactive gas. The thickness of may be set in the range of 2 to 10 nm.

A semiconductor device for a DRAM according to an embodiment of the present invention includes a dielectric film surrounding the lower electrode; and an upper electrode surrounding the dielectric layer. The upper electrode may be made of one or a combination of Ru, Ir, and TiN.

A semiconductor device for a DRAM according to an embodiment of the present invention includes a substrate having an active region; a first insulating layer formed on the substrate; a contact plug having one end connected to the active region through the first insulating layer and the other end exposed; a landing pad connected to the other end of the contact plug; an anti-oxidation film forming a conductive metal oxide film when oxidized on the top of the landing pad; a second insulating layer surrounding side surfaces of the landing pad and the anti-oxidation layer; a third insulating layer formed on the anti-oxidation layer and the second insulating layer; and a lower electrode of a capacitor having one end connected to the oxidation prevention film through a contact window formed in the third insulating layer and formed by filling the contact window with an atomic layer deposition (ALD) method using an oxygen-based reactive gas. It is characterized in that a conductive metal oxide film is formed between the oxidation prevention film and the lower electrode.

A method of manufacturing a semiconductor device for DRAM according to an embodiment of the present invention includes a first insulating layer formed on an upper portion of an active region of a substrate and a landing contacting the top of a contact plug connected to the active region through the first insulating layer. forming a metal film for a pad; forming an anti-oxidation metal film on top of the metal film for the landing pad using a rare metal that forms a conductive metal oxide film when oxidized; patterning the metal film for the landing pad and the metal film for oxidation to form a landing pad and an anti-oxidation film corresponding thereto; forming a second insulating layer surrounding side surfaces of the landing pad and the anti-oxidation film, and then forming a third insulating layer on top of the anti-oxidation film and the second insulating layer; and forming a contact window for contacting the oxide layer on the third insulating layer, and then filling the contact window with a rare metal by an atomic layer deposition (ALD) method using an oxygen-based reactive gas to form a lower electrode of a capacitor. and forming a conductive metal oxide film between the oxidation prevention film and the lower electrode.

In this case, the anti-oxidation layer may be deposited using Ru or Ir sputtering or chemical vapor deposition.

In addition, when the lower electrode of the capacitor is formed by an atomic layer deposition (ALD) method using an oxygen-based reactive gas, a metal organic compound may be used and deposited at a temperature of 300° C. or less. The metal organic compound may be any one of a carbonyl group, a diketone, and diamines.

In addition, a method of manufacturing a semiconductor device for DRAM according to another embodiment of the present invention contacts a first insulating layer formed on an upper portion of an active region of a substrate and an upper end of a contact plug connected to the active region through the first insulating layer. forming a metal film for a landing pad; forming a landing pad by patterning the metal film for the landing pad; After forming a second insulating layer surrounding the side surface of the landing pad, forming an oxidation prevention film using a rare metal that forms a conductive metal oxide film when oxidized on top of the landing pad; forming a fourth insulating layer on top of the antioxidant layer and the third insulating layer after forming a third insulating layer surrounding the side surface of the antioxidant layer; and forming a contact window for contacting the oxidation prevention film on the fourth insulating layer, and then filling the contact window with a rare metal by an atomic layer deposition (ALD) method using an oxygen-based reactive gas to form a lower electrode of a capacitor. and forming a conductive metal oxide film between the oxidation prevention film and the lower electrode.

In this case, the anti-oxidation layer may be deposited using Ru or Ir selective chemical vapor deposition.

Furthermore, a method of manufacturing a semiconductor device for DRAM according to another embodiment of the present invention contacts a first insulating layer formed on an upper portion of an active region of a substrate and an upper end of a contact plug connected to the active region through the first insulating layer. forming a metal film for a landing pad; forming a landing pad by patterning the metal film for the landing pad; forming a second insulating layer surrounding the side surface of the landing pad and then forming a third insulating layer on top of the landing pad and the second insulating layer; After forming a contact window for contacting the landing pad on the third insulating layer, an oxidation prevention film is formed on top of the landing pad exposed inside the contact window by using a rare metal that forms a conductive metal oxide film when oxidized. forming; and forming a lower electrode of a capacitor by filling the contact window with a rare metal by an atomic layer deposition (ALD) method using an oxygen-based reactive gas on the oxidation prevention film exposed inside the contact window. It is characterized in that a conductive metal oxide film is formed between the oxidation prevention film and the lower electrode.

In the method of manufacturing a semiconductor device for DRAM according to an embodiment of the present invention, after forming the lower electrode, removing the upper part of the substrate by CMP process to expose the third insulating layer, and then exposing the upper part of the lower electrode, the lower part removing the third insulating layer surrounding the electrode; forming a dielectric film to surround the lower electrode; and forming an upper electrode on a surface of the dielectric layer.

The present invention is to suppress deterioration of contact resistance of a DRAM capacitor using a noble metal lower electrode, and conduction between a lower electrode and a landing pad connecting an active region of a silicon substrate By inserting a metal having a metal oxide characteristic into the oxidation prevention film, even if the metal of the oxidation prevention film is oxidized by oxidation generated in the lower electrode formation process, it exists as a layer having conductive properties, thereby preventing deterioration of contact resistance.

As described above, in the present invention, when the lower electrode of the capacitor is manufactured using a rare metal having a large work function by the atomic layer deposition (ALD) method using an oxygen-based reactive gas, there is a gap between the landing pad and the lower electrode of the capacitor. Deterioration of the contact resistance that occurs can be prevented.

In addition, in the present invention, even when oxidation occurs on the uppermost surface layer of the landing pad in contact with the lower electrode of the capacitor, a rare metal ALD process using an oxygen-based reactive gas is performed by forming an oxidation prevention film with a conductive metal. However, since a conductive metal oxide film is formed on the top of the anti-oxidation film, the contact resistance does not deteriorate.

Furthermore, in the present invention, the contact resistance between the lower electrode of the capacitor and the landing pad connecting the semiconductor substrate is lowered to secure a timing margin when reading and writing the DRAM device, thereby improving performance and reliability of the DRAM device. can contribute to improving

In particular, according to the present invention, the technique of manufacturing the lower electrode of a capacitor using a rare metal having a large work function by the atomic layer deposition (ALD) method using an oxygen-based reactive gas is an atomic layer deposition (ALD) method used for increasing capacitance in DRAM. It is most necessary for semiconductor devices using a lower electrode of a rare metal (Ru or Ir) by layer deposition.

1A to 1G are cross-sectional views illustrating a method of manufacturing a semiconductor device for DRAM according to a first embodiment of the present invention.
2A to 2G are cross-sectional views illustrating a method of manufacturing a semiconductor device for DRAM according to a second embodiment of the present invention, respectively.
3A to 3G are cross-sectional views illustrating a method of manufacturing a semiconductor device for DRAM according to a third embodiment of the present invention, respectively.
4 is a cross-sectional view showing a lower electrode of a DRAM capacitor manufactured using a rare metal having a high work function by an atomic layer deposition (ALD) method using an oxygen-based reactive gas according to the present invention.
5A and 5B are graphs showing results of X-ray photoelectron spectroscopy (X-ray photoelectron spectroscopy) analysis for confirming the role of the antioxidant film of the semiconductor device for DRAM according to Comparative Examples and Examples, respectively.

Hereinafter, preferred embodiments according to the present invention will be described with reference to the accompanying drawings.

In this process, the size or shape of the components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms specifically defined in consideration of the configuration and operation of the present invention may vary according to the intentions or customs of users and operators. Definitions of these terms should be made based on the content throughout this specification.

In general, a semiconductor device includes a substrate having an active region defined by an isolation layer.

The substrate may include silicon (Si), for example, single crystal silicon, polycrystalline silicon, or amorphous silicon. In addition, the substrate may include a semiconductor material such as germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), gallium arsenide (GaAs), indium arsenide (InAs), or indium phosphide (InP). . In addition, the substrate may include a conductive region, for example, a well doped with impurities or an active region doped with impurities.

A plurality of conductive lines spaced apart from the substrate may be formed on the substrate with an insulating film interposed therebetween. The plurality of conductive lines may extend parallel to each other along one direction (Y direction) on the substrate. In this case, the plurality of conductive lines may constitute a plurality of bit lines.

A plurality of gate insulating layers, a plurality of word lines, and a plurality of buried insulating layers may be sequentially formed in the plurality of word line trenches formed in the memory cell region of the substrate.

The gate insulating film may be formed of at least one selected from a silicon oxide film, a silicon nitride film, a silicon oxynitride film, an oxide/nitride/oxide (ONO) film, or a high-k dielectric film having a higher dielectric constant than a silicon oxide film. The plurality of word lines may be formed of at least one material selected from Ti, TiN, Ta, TaN, W, WN, TiSiN, Mo, or WSiN. The plurality of buried insulating layers may be formed of a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, or a combination thereof.

A bit line connected to an active region of the substrate through a direct contact is formed on the substrate. A plurality of buried contacts connected to the active region of the substrate are formed on the first insulating layer covering the bit line. The plurality of buried contacts may be insulated from each other by a second insulating layer.

The direct contact may be made of polysilicon, metal, conductive metal nitride, or a combination thereof.

The bit line may include at least one material selected from a semiconductor doped with impurities, a metal, a conductive metal nitride, and a metal silicide. For example, the bit line may be made of doped polysilicon, TiN, TiSiN, W, tungsten silicide, or a combination thereof.

The plurality of buried contacts may be formed of a semiconductor doped with impurities, a metal, a conductive metal nitride, or a combination thereof.

Each of the first insulating layer and the second insulating layer may be formed of an oxide layer, a nitride layer, or a combination thereof. For example, the first insulating film and the second insulating film may be made of tetraethylorthosilicate (TEOS), high density plasma (HDP), or boro-phospho silicate glass (BPSG), but are not limited thereto.

The plurality of buried contacts may extend along the Z direction from both sides of the Y direction with respect to the bit line to be connected to the active region of the substrate. The plurality of buried contacts may have a structure including a contact plug contacting an active region of the substrate and a landing pad formed on the contact plug.

A plurality of capacitors connected to the plurality of buried contacts are formed on the second insulating layer. Each of the plurality of capacitors includes a lower electrode, an upper electrode, and a dielectric layer interposed between the lower electrode and the upper electrode.

In general, a semiconductor device for DRAM includes a plurality of memory cells and wires, and each memory cell includes one transistor and one capacitor. The wiring includes a plurality of bit lines and word lines for storing and reading data to and from a plurality of memory cells.

The transistor may be formed of, for example, a MOS transistor, and has a source region and a drain region in an active region. The capacitor may be electrically connected to a source region, and the wire, eg, a bit line, may be electrically connected to a drain region.

In this case, since the capacitor and the wiring have a structure disposed over the MOS transistor, the capacitor and the bit line are connected to the source region and the drain region through respective contact plugs. In this case, each contact plug may not be directly connected, but may be connected in contact with landing pads located on the source region and the drain region.

As described above, in the semiconductor device for DRAM, the connection structure between a transistor, a capacitor disposed thereon, a wiring, a bit line, and a word line may be very complex and diverse according to process miniaturization to increase the degree of integration in the DRAM device. .

However, from a large perspective, all semiconductor devices for DRAM include a substrate having an element-separated active region necessary for forming a MOS transistor, an insulating layer formed on top of the MOS transistor, a contact plug contacting the active region through the insulating layer, and the contact plug It includes a landing pad formed on top and a capacitor formed on top of the landing pad.

The present invention relates to a semiconductor device for DRAM capable of preventing deterioration of contact resistance occurring between a landing pad and a lower electrode of a capacitor, and a manufacturing method thereof. In the following description, the process prior to forming the landing pad is omitted and the landing pad The process from formation to capacitor formation is mainly explained.

1A to 1G are process cross-sectional views illustrating a method of manufacturing a semiconductor device for DRAM according to a first embodiment of the present invention.

First, in FIG. 1A, a portion omitted from the lower portion shows a substrate state in which, for example, an active region for forming a drain region and a source region is formed by doping an impurity into a semiconductor substrate, the upper portion of the substrate is omitted. shows the state in which the insulating layer is formed.

Referring to FIG. 1A , a contact window is formed in the first insulating layer 12 for contact with an active region, that is, a source region formed by doping a semiconductor substrate with impurities, and a conductive material, For example, the contact plug 10 is formed by filling polysilicon (Poly-Si) or polysilicon germanium (Poly-SiGe). Subsequently, a metal film 20a for a landing pad for forming a landing pad to contact the upper end of the contact plug 10 is formed using one or a combination of Ti, TiN, W, and Mo.

Subsequently, as shown in FIG. 1B, an anti-oxidation metal film 22a is formed on the landing pad metal film 20a to prevent oxidation of the landing pad 20. To this end, an anti-oxidation metal film 22a capable of forming a conductive metal oxide film when oxidized is formed on the top of the metal film 20a for the landing pad using a rare metal.

When oxidized, the anti-oxidation metal layer 22a having characteristics of a conductive metal oxide layer may use Ru or Ir. In this case, platinum (Pt), which is a rare metal, can also be considered, but platinum (Pt) is not suitable for the present invention because it is not oxidized and has a property of transmitting oxygen.

A general sputtering method or a chemical vapor deposition (CVD) method may be used to form the anti-oxidation metal layer 22a using Ru or Ir.

In this case, the deposition thickness of the anti-oxidation metal film 22a, that is, the anti-oxidation film 22 is determined by an oxygen-based reactive gas (eg, oxygen, When using ozone or oxygen radicals), it is required to form a metal film 20a for a landing pad, that is, to a thickness that does not react with an oxygen-based reactive gas.

In this case, when a deposition process of Ru or Ir is performed by an atomic layer deposition (ALD) method using an oxygen-based reactive gas to form the lower electrode 40, the oxide formed on the upper portion of the anti-oxidation film 22 by an oxidation reaction The thickness of the conductive metal oxide film 26 is 2 nm at most. Considering the maximum thickness of the conductive metal oxide film 26, the optimum thickness of the antioxidant film 22 is preferably 5 nm, and may be deposited at a maximum thickness of 10 nm. Here, the thickness of the anti-oxidation film 22 is required to prevent the deposition of a maximum thickness of 10 nm from providing a high level difference in an ultra-fine process. Therefore, it is preferable that the thickness of the anti-oxidation layer 22 is set in the range of 2 to 10 nm.

Afterwards, if the same pattern is formed by patterning the metal film 20a for the landing pad and the metal film 22a for oxidation by a dry etching method, the landing pad 20 and the upper surface of the landing pad 20 are formed as shown in FIG. 1C. An anti-oxidation film 22 corresponding to is obtained.

Subsequently, as a preliminary process for forming a capacitor on the top of the landing pad 20, a second insulating layer 24 is formed around the landing pad 20 by a deposition method, and a planarization process is performed.

After that, as shown in FIG. 1D, a third insulating layer 30 is formed as a thick film on the planarized second insulating layer 24 and the landing pad 20, for example, by using lithography and dry etching. A contact window 32 is formed to connect the oxidation prevention film 22, which is the uppermost layer of the landing pad 20, and the lower electrode 40 of the capacitor.

Subsequently, the lower electrode 40 of the capacitor is formed using Ru or Ir as a rare metal having a high work function. To this end, as shown in FIG. 1E, Ru or Ir is deposited on the inside of the contact window 32 by an atomic layer deposition (ALD) method using an oxygen-based reactive gas (eg, oxygen, ozone or oxygen radicals). Thus, the lower electrode film 40a is formed.

Here, atomic layer deposition (ALD) of Ru or Ir uses a metal organic compound to maintain high-level capacitor thickness uniformity at a temperature of 300 ° C or less. radical) is used to perform deposition. As the metal organic compound used at this time, a carbonyl group, a diketone, diamines, or the like can be used.

In this case, when the deposition process of Ru or Ir is performed by an atomic layer deposition (ALD) method using an oxygen-based reactive gas (eg, oxygen, ozone or oxygen radicals) to form the lower electrode film 40a, The oxidation prevention film 22 disposed below is oxidized by an oxygen-based reaction gas.

As a result, a metal oxide film 26 of RuO ₂ or IrO ₂ , which is an oxide of Ru or Ir, is formed on the upper layer of the oxidation prevention film 22 in contact with the lower electrode film 40a.

In this case, the metal oxide layer 26 of RuO ₂ or IrO ₂ has conductivity. Therefore, in the present invention, the contact resistance between the landing pad 20 and the lower electrode 40 of the capacitor 50 is connected through the conductive metal oxide film 26 between the antioxidant film 22 and the lower electrode film 40a. can suppress the increase in

That is, in the present invention, the upper surface of the landing pad 20 is oxidized as the lower electrode 40 of the capacitor 50 is formed after the anti-oxidation film 22 is formed on the upper part of the landing pad 20, thereby increasing the contact resistance. growth can be prevented.

Then, after removing the upper part of the lower electrode film 40a by CMP (Chemical Mechanical Polishing) treatment to expose the third insulating layer 30 in the structure of FIG. 1E, when the upper end of the lower electrode 40 is exposed, the lower The third insulating layer 30 surrounding the electrode 40 is removed by a wet etching method to expose the lower electrode 40 .

Subsequently, as shown in FIG. 1F , a dielectric layer 42 is formed to surround the exposed lower electrode 40 . The dielectric layer 42 may be formed of, for example, one or a combination of zirconium oxide (ZrO ₂ ), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), and titanium oxide (TiO ₂ ). It is not limited. The dielectric layer 42 may be formed by, for example, atomic layer (ALD) deposition.

Thereafter, an upper electrode 44 is formed on the surface of the dielectric film 42 by using a rare metal such as Ru or Ir or TiN (titanium nitride), and a rare metal is most suitable for the upper electrode.

As described above, in the present invention, the landing pad ( Deterioration of the contact resistance occurring between 10) and the lower electrode 40 can be prevented by forming an anti-oxidation layer 22 on the landing pad 20 .

That is, in the present invention, an oxide-based film 22 is formed of a metal that is conductive even when oxidation occurs on the uppermost surface layer of the landing pad 20 that contacts the lower electrode 40 of the capacitor 50, Even if a rare metal ALD process using a reactive gas of is performed, a conductive metal oxide film 26 is formed on the upper part of the antioxidant film 22, so that contact resistance does not deteriorate.

Moreover, in the present invention, the contact resistance between the lower electrode 40 of the capacitor 50 and the landing pad 20 connecting the semiconductor substrate is lowered, thereby timing the reading and writing of DRAM memory cells. By securing a margin, the performance and reliability of DRAM can be improved.

Referring to FIGS. 2A to 2G , in the method of manufacturing a semiconductor device for DRAM according to the second embodiment of the present invention, the landing pad 20 is formed to contact the upper end of the contact plug 10 in the same manner as in the first embodiment. The metal film 20a for the landing pad is formed using one or a combination of Ti, TiN, W, and Mo.

Subsequently, as shown in FIG. 2B, the landing pad 20 is formed by patterning the metal film 20a for the landing pad, and a second insulating layer 24 is formed around the landing pad 20 by a deposition method and planarized. proceed with the process

After that, as shown in FIG. 2C, an anti-oxidation film 22 is formed only on the top of the landing pad 20 by selective chemical vapor deposition (CVD). A rare metal capable of forming a conductive metal oxide layer 26 when oxidized may be used as the anti-oxidation layer 22 . Ru or Ir may be used as the rare metal.

The formation of the anti-oxidation layer 22 using Ru or Ir uses a metal organic ruthenium compound as a ruthenium raw material and ammonia (NH ₃ ) gas as a reactive gas. Since the selective deposition characteristics differ depending on the temperature, it is preferable to perform deposition using a low temperature of 300 ° C or less, and 250 ° C is a preferred deposition temperature.

As described above, after depositing ruthenium (Ru) or iridium (Ir) by selective chemical vapor deposition to complete the oxidation prevention film 22 on the top of the landing pad 20, thereafter, the lower electrode 40 of the capacitor 50, The process of forming the dielectric layer 42 and the upper electrode 44 may be performed in the same manner as shown in FIGS. 1D to 1G of the first embodiment and the process of FIGS. 2D to 2G, and details are omitted.

A method of manufacturing a semiconductor device for a DRAM according to a third embodiment of the present invention will be described below with reference to FIGS. 3A to 3G .

Referring to FIG. 3A, the landing pad metal film 20a for forming the landing pad 20 to contact the upper end of the contact plug 10 as in the first embodiment is one of Ti, TiN, W, and Mo. Or a combination thereof is formed using a film.

Subsequently, as shown in FIG. 3B , the landing pad 20 is formed by patterning the metal film 20a for the landing pad.

Then, as shown in FIG. 3C, after forming the second insulating layer 24 around the landing pad 20 by a deposition method and performing a planarization process, the planarized second insulating layer 24 and the landing pad 20 ), the third insulating layer 30 is formed as a thick film on the top, and a contact window 32 for contacting the landing pad 20 is formed using, for example, lithography and dry etching.

After that, as shown in FIG. 3D, an anti-oxidation film 22 is formed only on the top of the landing pad 20 through the contact window 32 by selective chemical vapor deposition (CVD). As the anti-oxidation film 22 , a rare metal capable of forming the conductive metal oxide film 26 when oxidized as described above may be used. Ru or Ir may be used as the rare metal.

For example, in the formation of the anti-oxidation film 22 using Ru, a metal organic ruthenium compound is used as a ruthenium raw material and ammonia (NH ₃ ) gas is used as a reactive gas. Since the selective deposition characteristics differ depending on the temperature, it is preferable to perform deposition using a low temperature of 300 ° C or less, and 250 ° C is a preferred deposition temperature.

As described above, after depositing ruthenium (Ru) or iridium (Ir) by selective chemical vapor deposition to complete the oxidation prevention film 22 on the top of the landing pad 20, thereafter, the lower electrode 40 of the capacitor 50, The process of forming the dielectric layer 42 and the upper electrode 44 may be performed in the same manner as in FIGS. 3E to 3G as the process shown in FIGS. 1E to 1G of the first embodiment, and details thereof are omitted.

Referring to FIG. 4 , in the semiconductor device for DRAM according to the present invention, when the lower electrode 40 of the capacitor 50 is formed on the landing pad 20, a rare metal (Ru or Ir) using an oxygen-based reactive gas is used. ) In consideration of the problem that oxidation of the uppermost surface layer occurs when the ALD process is performed, an anti-oxidation film 22 is formed of a conductive metal even when oxidation occurs on the top of the landing pad 20.

As a result, in the present invention, even if a rare metal (Ru or Ir) ALD process using an oxygen-based reactive gas is performed on the lower electrode 40 of the capacitor 50 on the landing pad 20, the upper portion of the anti-oxidation film 22 A conductive metal oxide film 26 is formed on the surface to prevent deterioration of contact resistance.

As described above, the present invention is to suppress the deterioration of the contact resistance of a DRAM capacitor using a lower electrode 40 of a noble metal having a large work function, and the lower electrode 40 and the silicon substrate A metal having a conductive metal oxide property is inserted into the anti-oxidation film 22 between the landing pads 20 connecting the active regions, and the anti-oxidation film 22 is formed by the oxidation generated in the process of forming the lower electrode. Even if it is oxidized, it is possible to prevent deterioration of contact resistance by allowing it to exist as a layer having conductive properties.

Hereinafter, when forming the lower electrode of a DRAM capacitor on the top of the landing pad of a semiconductor device for DRAM according to the present invention, when a metal having metal oxide characteristics is formed as an oxide prevention film, it will be investigated whether the deterioration of contact resistance can be suppressed. A test was conducted to determine.

(Comparative example)

First, as a comparative example, when Ru was used to form the lower electrode, an experiment was conducted in the following order to confirm oxidation of the landing pad.

On the silicon substrate on which silicon oxide (SiO ₂ ) is deposited, titanium nitride (TiN) and tungsten (W) serving as a landing pad are deposited by a sputtering method, and ruthenium is deposited on the surface by an ALD method to serve as a lower electrode. (Ru) deposition was carried out. At this time, a precursor containing a CO group was used as a ruthenium precursor, O ₂ was used as a reactive gas, and deposition was performed at a thickness of 5 nm at a deposition temperature of 250° C. In order to remove the natural oxide film on the surface of tungsten before deposition, the oxide film on the surface of the sample was removed with plasma in a hydrogen gas atmosphere, and then deposition was performed.

(Example)

As an example, on a silicon substrate on which silicon oxide (SiO ₂ ) is deposited, titanium nitride (TiN) and tungsten (W) serving as a landing pad are deposited by a sputtering method, and then ruthenium (Ru) is applied as an antioxidant film. Deposition was performed to a thickness of 5 nm by sputtering, and then, Ru deposition, which served as a lower electrode, was performed by the ALD Ru method under the same process conditions as in Comparative Example.

(XPS (X-ray Photoelectron Spectroscopy) Analysis)

Elements were investigated using XPS (X-ray photoelectron spectroscopy) analysis to confirm the composition of each layer material according to the depth of the thickness of each layer deposited for each sample obtained according to the comparative example process and the example process. In order to investigate the composition of each layer material in the depth direction of the deposited thickness, the surface composition is measured, and the material is sputter-etched with Ar gas for 10 seconds to cut the material in the thickness direction, and then the composition of the material is repeatedly measured to determine the thickness according to the thickness depth. The composition of the material was analyzed and the results are shown in FIGS. 5a and 5b.

In general, it is judged that there is no significant difference in oxidation when the amount of oxygen at the interface is less than 10%.

Referring to FIG. 5A, the X-ray Photoelectron Spectroscopy (XPS) analysis result of ruthenium (Ru) deposited by the ALD method on a sample obtained according to the comparative example process, that is, tungsten as a landing pad, shows that ALD-Ru and tungsten (W) Oxygen (O) element is visible in between, which shows that tungsten has been oxidized.

Referring to FIG. 5B, the result of XPS analysis after depositing Ru as an antioxidant film on a sample obtained according to the above example process, that is, tungsten as a landing pad, by a sputtering method and depositing ruthenium (Ru) on a lower electrode by an ALD method is It shows that no oxygen (O) element exists between sputtering Ru (Sp-Ru) and tungsten (W), and some oxygen (O) exists between ALD-Ru and sputtering Ru (Sp-Ru). It seems that part of the sputtering ruthenium (Sp-Ru) is oxidized, and this oxygen does not diffuse to the tungsten interface, forming a stable tungsten and oxide layer interface.

In the above, the present invention has been shown and described as specific preferred embodiments, but the present invention is not limited to the above embodiments and is common knowledge in the art to which the present invention belongs within the scope of not departing from the spirit of the present invention. Various changes and modifications will be possible by those who have

The present invention relates to a semiconductor device for a DRAM for interconnecting a landing pad connected to an active region of a substrate and a lower electrode of a capacitor without deterioration of contact resistance, and a rare metal (Ru) by atomic layer deposition used for increasing capacitance. Alternatively, it can be applied to the manufacture of DRAM devices using Ir) as a lower electrode.

10: contact plug 12: first insulating layer
20: landing pad 20a: metal film for landing pad
22: antioxidant film 22a: metal film for preventing oxidation
24: second insulating layer 26: conductive metal oxide film
30: third insulating layer 32: contact window
40: lower electrode 40a: lower electrode film
42: dielectric film 44: upper electrode
50: capacitor

Claims (20)

In the semiconductor device for DRAM having a landing pad connected to the lower electrode of the capacitor,
A semiconductor device for DRAM comprising an oxidation prevention film formed of a metal having conductivity characteristics when oxidized between the landing pad and the lower electrode. According to claim 1,
The lower electrode and the anti-oxidation film are each made of a rare metal. According to claim 1,
The rare metal is Ru or Ir semiconductor device for DRAM. According to claim 1,
The antioxidant film is a semiconductor device for DRAM deposited using sputtering or chemical vapor deposition. According to claim 1,
The lower electrode is a semiconductor device for DRAM formed by an atomic layer deposition (ALD) method of a rare metal using an oxygen-based reactive gas. According to claim 1,
The anti-oxidation film is formed to a thickness capable of preventing oxidation of the landing pad by an oxidation reaction with the reaction gas when the lower electrode is formed using an oxygen-based reaction gas. According to claim 1 or 6,
The semiconductor device for DRAM, wherein the thickness of the anti-oxidation film is set in the range of 2 to 10 nm. According to claim 1,
a dielectric film surrounding the lower electrode; and
A semiconductor device for DRAM further comprising an upper electrode surrounding the dielectric film. According to claim 8,
The upper electrode is a DRAM semiconductor device made of one or a combination of Ru, Ir, and TiN. a substrate having an active region;
a first insulating layer formed on the substrate;
a contact plug having one end connected to the active region through the first insulating layer and the other end exposed;
a landing pad connected to the other end of the contact plug;
an anti-oxidation film forming a conductive metal oxide film when oxidized on the top of the landing pad;
a second insulating layer surrounding side surfaces of the landing pad and the anti-oxidation film;
a third insulating layer formed on the anti-oxidation layer and the second insulating layer; and
A lower electrode of a capacitor having one end connected to the oxidation prevention film through a contact window formed in the third insulating layer and formed by filling the contact window with an atomic layer deposition (ALD) method using an oxygen-based reactive gas. contains,
A semiconductor device for DRAM wherein a conductive metal oxide film is formed between the oxidation prevention film and the lower electrode. According to claim 10,
The lower electrode and the anti-oxidation film are each made of a noble metal. forming a first insulating layer formed on an upper portion of an active region of a substrate and a metal film for a landing pad contacting an upper end of a contact plug connected to the active region through the first insulating layer;
forming an anti-oxidation metal film on top of the metal film for the landing pad using a rare metal that forms a conductive metal oxide film when oxidized;
patterning the metal film for the landing pad and the metal film for oxidation to form a landing pad and an anti-oxidation film corresponding thereto;
forming a second insulating layer surrounding side surfaces of the landing pad and the anti-oxidation film, and then forming a third insulating layer on top of the anti-oxidation film and the second insulating layer; and
After forming a contact window for contacting the oxidation prevention film on the third insulating layer, a rare metal is filled in the contact window by an atomic layer deposition (ALD) method using an oxygen-based reactive gas to form a lower electrode of a capacitor. Including;
A method of manufacturing a semiconductor device for DRAM in which a conductive metal oxide film is formed between the oxidation prevention film and the lower electrode. forming a first insulating layer formed on an upper portion of an active region of a substrate and a metal film for a landing pad contacting an upper end of a contact plug connected to the active region through the first insulating layer;
forming a landing pad by patterning the metal film for the landing pad;
After forming a second insulating layer surrounding the side surface of the landing pad, forming an oxidation prevention film using a rare metal that forms a conductive metal oxide film when oxidized on top of the landing pad;
forming a fourth insulating layer on top of the antioxidant layer and the third insulating layer after forming a third insulating layer surrounding the side surface of the antioxidant layer; and
After forming a contact window for contacting the oxidation prevention film on the fourth insulating layer, a rare metal is filled in the contact window by an atomic layer deposition (ALD) method using an oxygen-based reactive gas to form a lower electrode of a capacitor. Including;
A method of manufacturing a semiconductor device for DRAM in which a conductive metal oxide film is formed between the oxidation prevention film and the lower electrode. forming a first insulating layer formed on an upper portion of an active region of a substrate and a metal film for a landing pad contacting an upper end of a contact plug connected to the active region through the first insulating layer;
forming a landing pad by patterning the metal film for the landing pad;
forming a second insulating layer surrounding the side surface of the landing pad and then forming a third insulating layer on top of the landing pad and the second insulating layer;
After forming a contact window for contacting the landing pad on the third insulating layer, an oxidation prevention film is formed on top of the landing pad exposed inside the contact window by using a rare metal that forms a conductive metal oxide film when oxidized. forming; and
Forming a lower electrode of a capacitor by filling the contact window with a rare metal by an atomic layer deposition (ALD) method using an oxygen-based reactive gas on the oxidation prevention film exposed inside the contact window,
A method of manufacturing a semiconductor device for DRAM in which a conductive metal oxide film is formed between the oxidation prevention film and the lower electrode. According to claim 12,
The antioxidant film is a method of manufacturing a semiconductor device for DRAM in which Ru or Ir is deposited using sputtering or chemical vapor deposition. The method of any one of claims 12, 13 and 14,
When the lower electrode of the capacitor is formed by an atomic layer deposition (ALD) method using an oxygen-based reactive gas, a method of manufacturing a semiconductor device for DRAM deposited at a temperature of 300 ° C or less using a metal organic compound. According to claim 16,
The method of manufacturing a semiconductor device for DRAM, wherein the metal organic compound is any one of a carbonyl group, a diketone, and a diamine. The method of any one of claims 12, 13 and 14,
After forming the lower electrode, removing the upper portion of the substrate by CMP processing to expose the third insulating layer, and then removing the third insulating layer surrounding the lower electrode when the upper portion of the lower electrode is exposed;
forming a dielectric film to surround the lower electrode; and
The method of manufacturing a semiconductor device for DRAM, further comprising forming an upper electrode on a surface of the dielectric film. According to claim 13 or 14,
The step of forming an oxide film using a rare metal on the top of the landing pad is a method of manufacturing a semiconductor device for DRAM in which the oxide film is selectively formed only on the top of the landing pad by a selective chemical vapor deposition (CVD) method. According to claim 19,
The method of manufacturing a semiconductor device for DRAM in which the anti-oxidation film is formed by using a metal organic ruthenium compound as a ruthenium raw material and ammonia (NH ₃ ) gas as a reactive gas.

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