KR0161390B1 - Sputtering method for semiconductor device and sputtering apparatus for this method - Google Patents

Abstract

Disclosed are a sputtering deposition method for a semiconductor device and a sputtering apparatus used therein. Provided is a sputtering deposition method and a sputtering apparatus used therein, wherein a reactive gas is directly injected from the top of the wafer to the surface of the wafer and the reaction gas is exhausted downward from the bottom of the wafer. According to the present invention, since nitrogen gas is directly injected onto the wafer to participate in the reaction, and unreacted gas is directly exhausted downward to the lower portion of the wafer, the target surface is not nitrided by the unreacted gas, and thus compared with the conventional sputtering apparatus. Since the deposition rate can be greatly improved, manufacturing process time and manufacturing cost can be reduced.

Description

Sputtering method of semiconductor device and sputtering device used therein

1 is a schematic diagram of a conventional sputtering apparatus.

2 is a schematic view of a sputtering apparatus according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to metallization of highly integrated semiconductor devices, and more particularly, to a sputtering method capable of improving the deposition rate of titanium nitride (hereinafter referred to as TiN) and a sputtering apparatus used therein.

Since the wiring method of a semiconductor element becomes a factor which determines the speed | rate, yield, and reliability of a semiconductor device, it occupies the most important position in a semiconductor manufacturing process.

In recent years, the contact size has become very small and the aspect ratio has increased with the high integration and refinement | miniaturization of a semiconductor element. In particular, the contact hole size of a next-generation semiconductor device of 64 Megabit DRAM or more is 0.5 µm or less, and the aspect ratio is 3 or more. Therefore, in order to maintain the yield, speed and reliability of the semiconductor device, a contact hole having a high aspect ratio and a small size should be filled with a metal or an insulating layer.

Meanwhile, a tungsten plug (W-Plug) process has been proposed as a method of filling contact holes having a high aspect ratio. In particular, the tungsten plug process requires a TiN layer or a Ti layer as an adhesion layer or a barrier layer at the bottom. In general, such a TiN layer or a Ti layer is formed by a sputtering method, and the TiN layer or Ti layer formed by the sputtering method has poor step coverage. Therefore, the contact hole having a high aspect ratio and small size cannot be completely filled with the tungsten, which causes short circuit and reliability problems of the metal layer on the tungsten plug.

Recently, in order to improve the problem, a sputtering method using a collimator has been proposed in forming a TiN layer or a Ti layer. The collimator used in the sputtering method is used to improve the uniformity of the grown film by directing sputtered atoms (for example, TiN or Ti particles).

The TiN thin film sputtered using the collimator as described above is highly regarded as a diffusion preventing metal of the next-generation metal contact because the step coverage is superior to the conventional sputtered thin film and low resistivity can be obtained.

Generally, when sputtering a TiN thin film using a collimator, the film is formed by depositing titanium particles sputtered with ionized argon gas on a silicon wafer through a collimator on a titanium target surface used as a source. do. At this time, the nitrogen gas introduced into the reactive gas and the titanium particles react with each other to form a TiN thin film. Meanwhile, only titanium particles vertically incident on the surface of the silicon wafer through the collimator among the sputtered titanium particles are selectively reacted with nitrogen gas and deposited on the wafer surface. Therefore, the use of a collimator has the advantage of improving the uniformity of the film formed as well as the step coating property.

Referring to FIG. 1, a conventional sputtering apparatus employing a collimator and a method of forming a TiN thin film using the same will be described.

Referring to FIG. 1, reference numeral 10 denotes a support for supporting a wafer, 12 a silicon wafer on which a titanium nitride film is to be formed, 14 a target of a sputtered source material, and 16 an inert gas injector for inert gas injection. 18 is a reactive gas injector for gas injection used for reactive sputtering, 20 is a gas exhaust pump, 22 is a first electrode (cathode) bonded to the target, and 24 is a second electrode bonded to the support. 26 denotes a collimator for selectively depositing only titanium particles which are incident vertically, and 28 shields, respectively.

According to the conventional sputtering apparatus, the TiN thin film sputtered by argon gas reacts with the nitrogen gas injected through the reactive gas injector 18 through the collimator 26 to form a TiN thin film on the surface of the wafer 12. To form. The nitrogen gas used to form the TiN thin film is injected through a reactive gas injector 18 having a plurality of nozzles, and the excess unreacted gas is supplied to the gas exhaust pump 20 disposed at the side of the chamber. Through the chamber is exhausted. That is, nitrogen gas is diffused to the wafer surface through a nozzle positioned below the wafer 12 to react with titanium particles sputtered from the target to form a TiN thin film on the wafer 12. At this time, the unreacted nitrogen gas not participating in the reaction is exhausted to the outside of the chamber by the gas exhaust pump 20 installed on the side of the chamber.

However, among the unreacted nitrogen gas that did not participate in the TiN thin film formation, the nitrogen gas not exhausted by the gas exhaust pump 20 diffuses toward the titanium target 14 and reacts with the titanium target to nitride the titanium target surface. . As such, when the titanium target surface is nitrided, a titanium nitride film is generated, and thus the thin film deposition rate is greatly reduced, so that the sputtering yield is reduced. The decrease in sputtering yield eventually leads to a decrease in the manufacturing yield of the TiN thin film.

In addition, as shown in FIG. 1, when the collimator 26 is mounted between the titanium target 14 and the wafer 12, nitrogen gas diffused into the collimator 26 in the unreacted nitrogen gas passes through the collimator. Reacts with titanium to form titanium nitride on the inner wall of the collimator 26. Accordingly, the pore size of the collimator through which the titanium particles pass is reduced, thereby reducing the passage speed of the titanium particles.

As a result, according to the conventional sputtering apparatus employing the collimator 26, since only the atoms perpendicularly incident from the target 14 participate in the reaction, the step coverage is improved, but the deposition rate of the TiN thin film is greatly reduced. there is a problem.

An object of the present invention is to provide a sputtering method that can solve the problem caused by the diffusion of unreacted gas toward the target or collimator.

Another object of the present invention is to provide a sputtering apparatus suitable for the sputtering deposition method.

Sputtering method according to the present invention for achieving the above object,

In forming a thin film on a wafer by using a target made of a sputtered material and a reactive gas, an unreacted gas that does not participate in the reaction among the reactive gases is formed by directly injecting a reactive gas from the top of the wafer onto the wafer surface. It is evacuated downward from the bottom of the wafer so that it does not diffuse toward the target located above the wafer.

Sputtering apparatus according to the present invention for achieving the above another object, the target material of the sputtered source material; A first electrode adhered to one surface of the target; A support on which the first electrode is spaced apart from the opposite surface of the target surface to which the first electrode is bonded by a predetermined distance and on which the wafer is mounted; A second electrode bonded to the support; An inert gas injector, positioned between the target and the support, for inert gas injection; A reactive gas injector positioned between the inert gas injector and the support and injecting reactive gas directly into the wafer surface; And an exhaust pump positioned below the support to exhaust the unreacted gas downward so that the unreacted gas of the reactive gas injected through the reactive gas injector does not diffuse toward the target.

According to a preferred embodiment of the present invention, the reactive gas injector is a tube structure or a ring structure, the nozzle of the reactive gas injector is located on the lower surface of the reactive gas injector to directly inject reactive gas into the wafer. . Further, it is preferable that the inert gas is argon, and the reactive gas is nitrogen.

According to the present invention, the deposition rate of the TiN thin film can be improved by preventing nitrogen from being directly nitrided by directly injecting nitrogen gas onto the wafer surface and evacuating excess nitrogen gas that does not participate in the TiN formation reaction down the wafer. .

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

With reference to FIG. 2, the TiN thin film formation method using the sputtering apparatus by this invention is demonstrated.

2 is a schematic perspective view of a sputtering apparatus according to the present invention.

The sputtering apparatus according to the present invention includes a support 100 for supporting a wafer, a silicon wafer 102 mounted on the support 100 to form a titanium nitride film on the surface thereof, and a target made of a sputtered source material ( 104 is provided. In addition, between the support 100 and the target 104 is located between the inert gas injector 106 and the inert gas injector 106 and the support 100 is used for inert gas injection, the wafer ( 102 is further provided with a reactive gas injector 108 used to inject reactive gas directly into the surface and an exhaust pump 110 positioned below the wafer 102 to exhaust the reactive gas downward. A first electrode (anode) 112 is attached to the target, and a second electrode (anode) 114 is attached to the support. In addition, a collimator 116 is mounted between the target 104 and the wafer 102 to selectively deposit only vertically incident titanium particles, and a shield 118 to block sputtered particles from being deposited on the chamber inner wall. ) Is installed.

An inert gas such as argon is injected through the inert gas injector 106, and a reactive gas such as nitrogen is injected through the reactive gas injector 108.

In the sputtering apparatus according to the present invention, unlike the structure in which the reactive gas injector is positioned below the wafer in the conventional sputtering apparatus, the reactive gas injector 108 is positioned between the support 100 or the wafer 102 and the target. Thus, reactive gas injected from the reactive gas injector 108 to the wafer 102 surface diffuses in the opposite direction to the target 104.

In addition, unlike the structure in which the exhaust pump is located on the side of the chamber in the conventional sputtering device, the exhaust pump is disposed under the support 100. Therefore, unreacted gases in the reactive gas injected from the reactive gas injector 108 are not exhausted to the outside of the chamber by the exhaust pump 110 installed under the support 100. At this time, since the exhaust pump 110 is located below the support 110, the unreacted gases are exhausted in a direction opposite to the target 104 or the collimator 116 located above the support 100.

As described above, the sputtering apparatus according to the present invention is provided with a reactive gas injector 108 between the inert gas injector 106 and the support 100, and an exhaust pump 110 is installed below the support 110 to unreacted. By allowing the gases to exhaust downward, they prevent them from diffusing into the target or collimator. As a result, the target surface is prevented from being nitrided by reacting with the titanium target, and titanium nitride is prevented from being deposited on the inner wall of the collimator by reacting with the titanium particles passing through the collimator, so that the sputter deposition rate is improved.

Subsequently, a process of forming a thin film, for example a titanium nitride film, on a wafer using the sputtering apparatus shown in FIG. 2 will be described.

An inert gas, such as argon, is injected through the inert gas injector 106 into a vacuum chamber in which high voltage is applied to the first and second electrodes 112 and 114 to make the argon into a plasma state, that is, Ar + ions. These Ar + ions collide with a target, eg, titanium target 104, bonded to the electrode 112 having the opposite polarity, that is, the first electrode 112 to which minus (−) is applied, so that a source material such as titanium Is removed from the titanium target 104. The titanium, away from the target 104, moves toward the wafer 102 and reacts with nitrogen injected from the reactive gas injector 108 to form a titanium nitride film on the wafer 102.

Unlike the related art, the nitrogen gas used as the reaction gas is injected directly onto the wafer through the nozzle of the reactive gas injector 108 positioned on the wafer, and the TiN thin film is formed by reacting with titanium atoms sputtered from the target. In addition, the unreacted nitrogen gas is exhausted to the outside of the chamber by the exhaust pump 110 installed under the support (100). That is, the gas that does not participate in the formation of the TiN thin film among the nitrogen gas injected on the wafer 102 is exhausted downward through the exhaust pump 110.

As described above, in the sputtering apparatus according to the present invention, a reactive gas injector 108 is installed between the inert gas injector 106 and the support 100, and an exhaust pump 110 is installed below the support 110. Thus, a reactive gas such as nitrogen gas is introduced directly above the wafer to participate in the reaction, and the unreacted nitrogen gas is immediately exhausted down the wafer. As a result, the target surface is prevented from being nitrided by the unreacted gas, so that the deposition rate can be greatly improved as compared with the conventional sputtering apparatus. In particular, in the case of employing a collimator to selectively deposit only vertically incident titanium particles, not only the step coverage of the deposited thin film can be improved, but also the titanium nitride is prevented from being deposited on the inner wall of the collimator, thereby greatly increasing the sputtering speed. Can be improved. Therefore, the manufacturing process time and the manufacturing cost can be reduced.

The present invention is not limited to the above embodiments, and it is apparent that many modifications are possible by those skilled in the art within the technical idea to which the present invention pertains.

Claims (6)

In the sputtering method of forming a thin film on a wafer using a target made of a sputtered material and a reactive gas, a thin film is formed by directly injecting a reactive gas onto the wafer surface from the top of the wafer, and does not participate in the reaction in the reactive gas. A sputtering method, wherein the unreacted gas is exhausted downward from the bottom of the wafer so that the unreacted gas does not diffuse toward the target located above the wafer. A target of sputtered source material; A first electrode adhered to one surface of the target; A support on which the first electrode is spaced apart from the opposite surface of the target surface to which the first electrode is bonded by a predetermined distance and on which the wafer is mounted; A second electrode bonded to the support; An inert gas injector, positioned between the target and the support, for inert gas injection; A reactive gas injector positioned between the inert gas injector and the support and injecting reactive gas directly into the wafer surface; And an exhaust pump positioned below the support to exhaust the unreacted gas downward so that unreacted gas of the reactive gas injected through the reactive gas injector is not diffused toward the target. The sputtering apparatus according to claim 2, wherein the reactive gas injector is a tube structure or a ring structure. The sputtering apparatus of claim 2, wherein a nozzle of the reactive gas injector is positioned at a lower surface of the reactive gas injector to directly inject reactive gas into the wafer. The sputtering apparatus according to claim 2, wherein the inert gas is argon and the reactive gas is nitrogen. A target of sputtered source material; A first electrode adhered to one surface of the target; A support on which the first electrode is spaced apart from the opposite surface of the target surface to which the first electrode is bonded by a predetermined distance and on which the wafer is mounted; A second electrode bonded to the support; An inert gas injector, positioned between the target and the support, for inert gas injection; A reactive gas injector positioned between the inert gas injector and the support and injecting reactive gas directly into the wafer surface; A collimator positioned between the target and the reactive gas injector and selectively passing only sputter particles vertically incident from the target; And an exhaust pump positioned below the support to exhaust the unreacted gas downward so that unreacted gas of the reactive gas injected through the reactive gas injector does not diffuse toward the target or the collimator. Device.