KR20000045868A - Method for manufacturing capacitor of semiconductor device - Google Patents

Abstract

PURPOSE: A capacitor manufacturing method of a semiconductor device is to ensure a high capacitance by suppressing a growth of a natural oxide film between a lower electrode and a high dielectric Ta2O5 film. CONSTITUTION: A method for fabricating a capacitor of a semiconductor device comprises the steps of: forming a lower electrode(30') consisting of a conductive layer, connected to a semiconductor substrate(10) through a contact hole of an interlayer insulating film(20); forming a thin silicon nitride film(32) on an upper surface of the lower electrode by using NH3/SiH2Cl2 gas within a single wafer chamber or a batch furnace; forming a Ta2O5 film(34) as a dielectric between electrodes on an upper surface of the silicon nitride film; and forming an upper electrode(36) consisting of the conductive layer on an upper surface of the Ta2O5 film. The silicon nitride film is formed under a temperature condition of 630 to 710°C and a pressure condition of 0.2 to 0.5 Torr within the batch furnace, and under a temperature condition of 630 to 690°C and a pressure condition of 0.8 to 1.2 Torr within the single wafer chamber.

Description

Capacitor Manufacturing Method of Semiconductor Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor of a semiconductor device, and more particularly, to a method of manufacturing a capacitor of a semiconductor device capable of achieving high capacitance by preventing oxidation of a lower electrode during a capacitor manufacturing process having a Ta ₂ O ₅ film as a high dielectric material.

At present, in order to achieve high integration of semiconductor devices, research / development has been actively conducted on reduction of cell area and reduction of operating voltage. In addition, as the integration of semiconductor devices increases, the area of the capacitor decreases drastically, but the charge required for the operation of the memory device, that is, the capacitance secured in the unit area must be increased.

In order to secure sufficient dielectric capacity of the capacitor, structural studies such as thinning the dielectric film and increasing the effective surface area, and materials to replace the dielectric film used as a silicon oxide film with a nitride film / oxide film, oxide film / nitride film / oxide film, or Ta ₂ O ₅ film Research is ongoing. More recently, the high dielectric film of the Ta ₂ O ₅ film capable of securing high capacitance is more than the nitride / oxide film, oxide film / nitride film / oxide film low dielectric film, which have difficulty in securing capacitance, so that it can be applied to devices of 256MD or more in the future. I use it.

However, the Ta ₂ O ₅ film has a higher dielectric constant than the silicon oxide film and the silicon nitride film, but has a large leakage current density and a low dielectric breakdown voltage, which makes it difficult to use in DRAM. In order to prevent the disadvantages of the Ta ₂ O ₅ film, specifically, in order to prevent excess oxygen in the Ta ₂ O ₅ film from diffusing to the lower electrode interface and bonding to silicon at the interface during subsequent ozone treatment, rapid thermal and forming the thin nitride film is subjected to Nitridation) process, and has been subjected to plasma treatment using an ozone treatment and oxygen-based gas in order to suppress the upper electrode metal and Ta ₂ O ₅ film reaction, Ta ₂ O ₅ film, the leakage current In order to improve the characteristic, the thermal oxidation process is implemented.

The capacitor formed by the manufacturing process sequence cannot rapidly nitride the surface of the lower electrode by a rapid thermal process, and thus the lower electrode and the lower electrode during the O ₂ to N ₂ O heat treatment process performed after Ta ₂ O ₅ film deposition. A natural oxide film is formed between the Ta ₂ O ₅ films. Capacitance is reduced by the natural oxide film formed due to the excessive oxidation reaction between the lower electrode and the dielectric film, thereby degrading the reliability of the capacitor.

An object of the present invention is a high temperature heat and then batch-type furnace to Ta ₂ O ₅ film deposited by forming the lower electrode nitride film of 20Å or less in the top surface at a selected reaction chamber in a single wafer chamber to solve the problems of the prior art The present invention provides a method of manufacturing a capacitor of a semiconductor device capable of securing high capacitance by suppressing growth of a native oxide film between a lower electrode and a high dielectric Ta ₂ O ₅ film that may be generated during an oxidation process.

Another object of the present invention is a high temperature thermal oxidation process for supplying oxygen after Ta ₂ O ₅ film deposition by nitriding the lower electrode surface at a pressure of 1 Torr or more using low pressure chemical vapor deposition to solve the problems of the prior art as described above. The present invention provides a method of manufacturing a capacitor of a semiconductor device capable of securing high capacitance by suppressing the growth of an oxide film between a lower electrode and a high-k dielectric Ta ₂ O ₅ film, which may be generated during the process.

In order to achieve the above object, the present invention provides a lower electrode in contact with a region of a semiconductor device, an upper electrode thereon, and the electrodes through a contact hole of an interlayer insulating film for inter-device insulation on a semiconductor substrate including a semiconductor device. In the manufacturing process of a capacitor consisting of a high dielectric Ta ₂ O ₅ film inherent to the step of forming a lower electrode made of a conductive layer in contact with a semiconductor element through a contact hole of an interlayer insulating film, in a batch furnace to a single wafer chamber Forming a nitride film of 20 kΩ or less on the upper surface of the lower electrode in the selected reaction chamber, forming a Ta ₂ O ₅ film as the interelectrode dielectric on the upper nitride film, and forming a conductive layer on the upper surface of the Ta ₂ O ₅ film. It comprises a step of forming a top electrode made of. Preferably, the formation of the nitride film is carried out in a batch furnace, using a NH ₃ / SiH ₂ Cl ₂ gas at a temperature of 630 to 710 ℃, process conditions of 0.2 to 0.5 Torr, but if in a single wafer chamber The surface NH ₃ / SiH ₂ Cl ₂ gas is used to proceed at a temperature condition of 630 to 690 ° C. and a process condition of 0.8 to 1.2 Torr.

In order to achieve the above object, the capacitor manufacturing method of the present invention comprises the steps of forming a lower electrode made of a conductive layer in contact with a semiconductor device through a contact hole of an interlayer insulating film for inter-device insulation on a semiconductor substrate having a semiconductor device; Nitriding the lower electrode surface by low pressure chemical vapor deposition in a reaction chamber selected from a batch furnace to a single wafer chamber; forming a Ta ₂ O ₅ film as the inter-electrode dielectric on the nitrided lower electrode; And forming an upper electrode formed of a conductive layer on an upper surface of the Ta ₂ O ₅ film. At this time, the nitriding treatment is preferably carried out using a NH ₃ gas under a temperature condition of 750 to 800 ° C. and a pressure condition of 1 to ₃ Torr in the reaction chamber.

1 to 4 are vertical cross-sectional views sequentially showing a capacitor manufacturing process of a semiconductor device according to the present invention.

* Description of the symbols for the main parts of the drawings *

10: silicon substrate

20: interlayer insulating film

30: silicon pattern

30 ': lower electrode

32: silicon nitride film

34: Ta ₂ O ₅ membrane

36: upper electrode

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

1 to 4 are vertical cross-sectional views sequentially showing a capacitor manufacturing process of a semiconductor device according to the present invention. Referring to this, the capacitor manufacturing method of the present invention is as follows.

First, as a semiconductor substrate, a semiconductor device (not shown) having a gate electrode and a source / drain is formed on the upper surface of the active region of the silicon substrate 10, and USG (Undoped Silicate Glass) or BPSG is formed on the entire surface of the substrate 10. (Boro Phospho Silicate Glass) and a material selected from SiON is deposited and a chemical mechanical polishing process is performed to form an interlayer insulating film 20. In order to secure the cross-sectional area of the capacitor in contact with the active region of the substrate 10, that is, the drain region, the interlayer insulating layer 20 is selectively etched by photolithography and etching to form a contact hole (not shown). As illustrated, the silicon layer 30 is amorphous and doped with impurities to be buried in the entire surface of the interlayer insulating layer 20 having the contact hole, and the silicon layer 30 is patterned in the form of a cylinder using an etching process. Then, the silicon pattern 30 is grown to a selective MPS (Metastable PolySilicon) structure to complete the lower electrode 30 'having a concave-convex surface, thereby increasing the surface area of the electrode. The uneven lower electrode 30 'formed by the movement of silicon atoms (Si) is treated with PH ₃ to supply the lower electrode 30' to supply enough P to cause a depletion of capacitance due to lack of phosphorus (P). Do it.

Subsequently, as shown in FIG. 3, a thin silicon nitride film (Si ₃ N ₄ ) 32 is formed on the top surface of the lower electrode 30 ′ in the batch furnace, and when the thickness of the film 32 is thick, the capacitance is reduced. Therefore, it is preferable to set it as 20 kPa or less. This process is performed using NH ₃ / SiH ₂ Cl ₂ gas at a temperature of 630 to 710 ° C. and a pressure of 0.2 to 0.5 Torr.

In addition, the process of forming the silicon nitride film 32 may be performed in a single wafer chamber. In this case, a temperature of 630 to 690 ° C. and a pressure of 0.8 to 1.2 Torr using NH ₃ / SiH ₂ Cl ₂ gas may be used. To be carried out. As described above, the silicon nitride film 32 forming process of the single wafer chamber includes two chambers in the same system, and the silicon nitride film 32 pretreatment process and the dielectric film Ta ₂ O ₅ to be described later are sequentially performed. Throughput and productivity can be improved.

Next, as shown in FIG. 4, on the silicon nitride layer 32 by low pressure chemical vapor deposition using TaCl ₅ to Ta (OC ₂ H ₅ ) ₅ and O ₂ gas, which are high dielectric materials. A Ta ₂ O ₅ film 34, which is an interelectrode dielectric, is formed. And, and the process after the film quality to enhance the Ta ₂ O ₅ film 34, the oxygen space, removal of the carbon-based impurities in the Ta ₂ O ₅ film (34). In this case, the post-treatment process may be performed by selecting any one or two or more from a low temperature O ₂ to N ₂ O plasma treatment, a high temperature O ₂ to N ₂ O heat treatment, UV (Ultra Violet) -O ₃ .

Thereafter, a thermal oxidation process is performed on the resultant, and TiN to WN are applied to the upper surface of the Ta ₂ O ₅ film 34 by chemical vapor deposition, followed by patterning it using an etching process to form the upper electrode 36. Form.

On the other hand, the pretreatment process performed on the lower electrode 30 'before the Ta ₂ O ₅ film 34 is formed in the manufacturing process of the present invention instead of forming the thin silicon nitride film 32 in the batch furnace to the single wafer chamber. The surface of the lower electrode 30 ′ may be nitrided by using NH ₃ gas in a low pressure chemical vapor deposition method in any reaction chamber. At this time, the process is to proceed to a temperature of 750 ~ 800 ℃, pressure conditions of 1 ~ 3 Torr.

Therefore, the capacitor manufacturing method according to the manufacturing process sequence of the present invention is subjected to the NH ₃ heat treatment at a pressure of 1 Torr or more prior to the formation of the Ta ₂ O ₅ film 34 to nitrate the surface of the lower electrode 30 ', 32 deposits a silicon atom (Si) and a nitrogen (N) atom of the lower electrode 30 'to form an atomic bond, thereby forming the Ta ₂ O ₅ film 34 to form the lower electrode 30' during the oxidation process. And the interface between the Ta ₂ O ₅ film 34 is maintained in a stable surface state.

As described above, in the present invention, even when the lower electrode is nitrided according to the conventional capacitor manufacturing process, the surface nitride film of the lower electrode sufficiently prevents the growth of the natural oxide film during the oxidation process after forming the Ta ₂ O ₅ film. To improve the failure to act as a barrier, in the reaction chamber selected from a batch furnace or a single wafer chamber, a nitride film of 20 kW or less is formed on the upper surface of the lower electrode or nitrided by low pressure vapor deposition. the ₂ O ₅ film growth of a native oxide film deposited between the lower electrode after the high temperature heat that can be generated during the oxidation step and the high-dielectric Ta ₂ O ₅ film is suppressed.

Therefore, the present invention can maintain a high-quality dielectric material by preventing oxidation of the lower electrode, thereby ensuring a high capacitance and at the same time improving the reliability of the capacitor.

Claims (6)

The lower electrode in contact with any region of the semiconductor device, the upper electrode thereon, and the high dielectric material Ta ₂ O ₅ inherent in the electrodes through the contact hole of the interlayer insulating film for inter-device insulation on the semiconductor substrate including the semiconductor device. In the manufacturing process of a capacitor consisting of a film, Forming a lower electrode made of a conductive layer in contact with a semiconductor device through a contact hole of the interlayer insulating film; Forming a thin silicon nitride film using NH ₃ / SiH ₂ Cl ₂ gas on an upper surface of the lower electrode in a reaction chamber selected from a batch furnace or a single wafer chamber; Forming a Ta ₂ O ₅ film as the interelectrode dielectric on the silicon nitride film upper surface; And forming an upper electrode formed of a conductive layer on an upper surface of the Ta ₂ O ₅ film. 2. The method of claim 1, wherein the silicon nitride film is formed in a batch furnace at a temperature of 630 to 710 DEG C and a pressure of 0.2 to 0.5 Torr. The method of claim 1, wherein the silicon nitride film is formed in a single wafer chamber at a temperature of 630 to 690 ° C. and a pressure of 0.8 to 1.2 Torr. The method of manufacturing a capacitor of a semiconductor device according to claim 1, wherein the silicon nitride film has a thickness of 20 kW or less. The lower electrode in contact with any region of the semiconductor device, the upper electrode thereon, and the high dielectric material Ta ₂ O ₅ inherent in the electrodes through the contact hole of the interlayer insulating film for inter-device insulation on the semiconductor substrate including the semiconductor device. In the manufacturing process of a capacitor consisting of a film, Forming a lower electrode made of a conductive layer in contact with a semiconductor device through a contact hole of the interlayer insulating film; Nitriding the lower electrode surface by low pressure chemical vapor deposition in a reaction chamber selected from a batch furnace to a single wafer chamber; Forming a Ta ₂ O ₅ film as the inter-electrode dielectric on the nitrided lower electrode; And forming an upper electrode formed of a conductive layer on an upper surface of the Ta ₂ O ₅ film. 6. The method of claim 5, wherein the nitriding process is performed in a reaction chamber under a temperature condition of 750 to 800 DEG C and a pressure condition of 1 to 3 Torr.