Patent Application
20050156258
Priority is claimed to Korean Patent Application No. 2003-86509, filed on Dec. 1, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a method of forming a material film, and more particularly, to a method of forming a silicide film having excellent thermal stability, a semiconductor device and a semiconductor memory device comprising the silicide film formed using the same, and methods of manufacturing the semiconductor device and the semiconductor memory device.
2. Description of the Related Art
As the integrity of semiconductor devices increases, the size of semiconductor devices such as metal oxide semiconductor field effect transistors (MOSFET) or capacitors decreases below the micron range.
As the size of a semiconductor device becomes smaller than the micron range, the parasitic resistance of the contact region of the semiconductor device, for example, the parasitic resistances of the contact region of the gate, the source, and the drain of MOSFET, increase. As the parasitic resistance increases, RC delay increases, thereby lowering the speed of the semiconductor device.
To solve these problems, a silicide film, which is a reactive product of silicon (Si) and metal, is formed on a contact region to lower a surface resistance and a contact resistance of the contact region.
A titanium silicide (TiSi2) layer and a cobalt silicide (CoSi2) layer have been used widely. These two silicide layers have a low specific resistance that is appropriate for the high-speed operation of a semiconductor device.
However, the titanium silicide layer and the cobalt silicide layer have the following defects. The titanium silicide layer generates shorts caused by bridging, and shows a narrow line effect. Accordingly, it is difficult to apply the titanium silicide layer to a semiconductor device. The cobalt silicide layer, although it has better characteristics than the titanium silicide layer, requires a lot of silicon to be formed. It may be difficult to apply the cobalt silicide layer to a semiconductor device having a shallow junction.
Due to such problems of the titanium silicide layer and the cobalt silicide layer, a new silicide layer such as a nickel mono silicide (NiSi) layer has been developed. The nickel mono silicide layer has specific resistance (14 μΩ•cm) similar to that of the titanium silicide and the cobalt silicide, but has no bridging problem or narrow line effect. The amount of required silicon is much less than the silicon required for the cobalt silicide.
However, when the nickel mono silicide is used in the manufacturing process of a semiconductor device, the following problems arise.
In the manufacturing process of a semiconductor device, an annealing process for reflow is performed after an interlayer dielectric such as a BPSG (borophosphosilicate glass) film is formed. The annealing process is performed at a temperature higher than 700° C., which is much higher than temperature required for the formation of the nickel mono silicide. During the annealing process, since the nickel mono silicide is converted into NiSi2 which has a high specific resistance, the parasitic resistance of a semiconductor device is increased, thereby deteriorating the performance of the semiconductor device.
The present invention provides a semiconductor device comprising a silicide film on which sheet resistance is low and thermal stability is excellent.
The present invention also provides a semiconductor memory device including the semiconductor device.
The present invention also provides a method of manufacturing the silicide film used in the semiconductor memory device including the semiconductor device.
The present invention also provides a method of manufacturing the semiconductor device.
The present invention also provides a method of manufacturing the semiconductor memory device.
According to an aspect of the present invention, there is provided a transistor comprising a substrate containing silicon and including a source, a drain, and a gate disposed on the substrate between the source and the drain, wherein a nickel mono silicide (NiSi) film including germanium is formed on at least one of the upper surfaces of the source, the drain, and the gate.
According to another aspect of the present invention, there is provided a semiconductor memory device comprising a transistor, a capacitor connected to the transistor, and a nickel silicide film including germanium interposed between the transistor and the capacitor.
The semiconductor memory device may comprise a conductive plug connecting a drain of the transistor and a lower electrode of the capacitor, wherein the upper surface of the conductive plug is the nickel silicide film including germanium.
The surface layer of the drain may the nickel silicide film including germanium.
According to still anther aspect of the present invention, there is provided a magnetic memory device comprising a transistor, a magnetic resistant, and a nickel silicide film including germanium interposed between the transistor and the magnetic resistant.
The magnetic resistant may be a Magnetic Tunneling Junction cell.
According to an aspect of the present invention, there is provided a method of forming a silicide film, comprising the steps of forming a temporary film that can be absorbed in a reaction between silicon and a metal on a substrate containing silicon, forming a metal film that can react with the silicon in a subsequent annealing process on the temporary film, and forming a metal silicide film on the upper surface layer of the substrate by annealing the substrate on which the metal film and the temporary film are formed.
The temporary film may be a germanium film.
The metal film may be a nickel film.
The substrate may be one selected from the group consisting of a single crystal silicon substrate, a poly-silicon substrate, a doped silicon substrate, an amorphous silicon substrate, a silicon germanium substrate, a silicon nitride substrate and a silicon carbide substrate.
The annealing the product may comprise performing for several tens of seconds under a nitrogen gas atmosphere at a temperature of 300-1000° C. using RTA.
After forming the metal silicide film, the metal film may be removed.
The germanium film may be formed to a thickness of 2-10 nm and the metal film may be a nickel film.
According to another aspect of the present invention, there is provided a method of forming a transistor, comprising the steps of forming a gate stack including a gate insulating film and a gate electrode on a substrate containing silicon, forming a shallow impurity layer on the substrate adjacent to the gate stack, forming gate spacers on both sides of the gate stack, forming a deep impurity layer in the shallow impurity layer adjacent to the gate spacers to form a source and a drain which are composed of the shallow impurity layer and the deep impurity layer, and forming a nickel silicide film including germanium on at least one of the surfaces of the source, the drain, and the gate electrode.
The forming the nickel silicide film may further comprise forming a germanium film that covers the source, the drain, and the gate stack and is absorbed in a reaction between the silicone and a metal on the substrate, forming a nickel film on the germanium film, and annealing the resultant product where the nickel film is formed.
The resultant product may be annealed for several tens of seconds under the nitrogen gas atmosphere at a temperature of 300-1000° C. using RTA.
A portion of the nickel film that remains after annealing the resultant product may be removed.
The substrate may be one selected from the group consisting of a single crystal silicon substrate, a poly-silicon substrate, a doped silicon substrate, an amorphous silicon substrate, a silicon germanium substrate, a silicon nitride substrate and a silicon carbide substrate.
According to an aspect of the present invention, there is provided a method of manufacturing a semiconductor memory device, comprising forming a transistor on a substrate containing silicon, forming an interlayer insulating layer that covers the transistor on the substrate, forming a contact hole exposing a part of the transistor in the interlayer insulating layer, filling the contact hole with a conductive plug, transforming the surface layer of the conductive plug into a silicide film having better thermal stability than TiSi, CoSi, and NiSi, and forming a data storage unit that contacts the silicide film on the interlayer insulating layer.
A silicide film having better thermal stability than that of TiSi, CoSi, and NiSi may be formed on a part of the transistor to be exposed through the contact hole before the forming the interlayer insulating layer.
The substrate may be one selected from the group consisting of a single crystal silicon substrate, a poly-silicon substrate, a doped silicon substrate, an amorphous silicon substrate, a silicon germanium substrate, a silicon nitride substrate and a silicon carbide substrate.
The data storage unit may be one of a capacitor and a MTJ cell.
The silicide film may be formed with a nickel silicide film including germanium.
The forming the nickel silicide film including the germanium may further comprise forming a germanium film that can be absorbed into the nickel silicide film including germanium on a lower material film where the nickel silicide film including germanium is to be formed, forming a nickel film on the germanium film, annealing the resultant product where the nickel film is formed, and removing a remaining portion of the nickel film.
The resultant product may be annealed for several tens of seconds under a nitrogen gas atmosphere at a temperature of 300-1000° C. using RTA.
The silicide film may be a nickel silicide film including germanium.
Use of the foregoing embodiments of the present invention makes it possible to manufacture a silicide film whose thermal stability is higher than the thermal stabilities of TiSi, CoSi, and NiSi. Such a silicide film is applied to a semiconductor device, a semiconductor memory device, etc., resulting in decreased parasitic resistances of the device and thus improving operating characteristics thereof.
The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
The present invention will now be described more fully with reference to the accompanying drawings. In the drawings, the thicknesses of layers and regions are exaggerated for clarity.
A method of forming a silicide film according to an embodiment of the present invention will now be described with reference to
Referring to
The temporary film 12 and the metal film 14 may be formed using an e-beam evaporator. Also, a CVD, a PVD, a MOCVD, a MBE, or a sputtering method may be used since these methods allow for the easy control of thickness.
As described above, the temporary film 12 and the metal film 14 are sequentially formed on the substrate 10, and then the product is heated for a predetermined time at a predetermined temperature. For example, when the temporary film 12 is a germanium film with a thickness of 2-10 nm, and the metal film 14 is a nickel film with a thickness of about 30 nm, the product comprising sequentially stacked the temporary film 12 and the metal film 14 is annealed using rapid thermal annealing (RTA) for 30 seconds under a nitrogen gas atmosphere at a temperature of 300-1000° C. In this process, a component of the metal film 14 and a component of the substrate 10 react with each other to form a silicide film 16 that includes the component of the metal film 14 and the component of the substrate 10 on the substrate 10, as shown in
However, part of the temporary film 12 may remain after the formation of the silicide film 16 is completed, although, the temporary film 12 is mostly absorbed into the silicide film 16 in the formation of the silicide film 16. Hence, the thickness of the remaining temporary film 12 is quite a bit less than that of the original temporary film 12 formed, and the remaining temporary film 12 is inconsequential. The characteristics of the silicide film 16 are not influenced by the remaining part of the temporary film 12.
The silicide film 16 may be a nickel mono silicide (NiSi) film. The metal film 14 can be completely exhausted in the process of forming the silicide film 16, or a part 14a of the metal film 14 may remain, as shown in
The silicide film 16 has several important physical properties when the silicide film 16 is a nickel mono silicide film.
As described above, when a nickel film and a germanium film are respectively used as the metal film 14 and the temporary film 12 to form a nickel mono silicide film (hereinafter referred to as NiSi of the present invention), free energy of the nickel mono silicide film is increased than that of a nickel mono silicide formed using a conventional method (hereinafter referred to as NiSi of the prior art).
Referring to
The results shown in
With respect to the NiSi of the prior art, the first NiSi, and the second NiSi formed by the annealing process at several temperatures, the results of glancing angle X-ray diffraction (GXRD) will now be described.
Referring to
Such a result show that for the NiSi of the prior art, the temperature of formation is 700° C., at which point some of the NiSi is changed to the NiSi2.
Meanwhile, referring to
To be specific, as shown in
Referring to
That is, with respect to the second NiSi, only the NiSi exists even when the temperature reaches 850° C., and both the NiSi and the NiSi2 exist when the temperature reaches 850° C. This means that when the temperature of the second NiSi is 850° C., some of the second NiSi is changed to the NiSi2.
The results shown in
Referring to
Referring to
The results shown in
Referring to
Referring to
Meanwhile, by calculating the concentration of germanium included in the second NiSi film (SF2) from the germanium distribution curve (∘), the germanium of 2.5-3% is uniformly distributed in the second NiSi film (SF2).
Since the germanium is included in the second NiSi film (SF2), the second NiSi film (SF2) can be expressed as NiSi1-xGex.
The EDXS profile shown in denotes the silicon distribution of the first NiSi film (SF1), the reference symbol ∘ denotes the germanium distribution of the first NiSi film (SF1).
Referring to
The second part P2, which has bright contrast, has a germanium of 2.5%-3%, which can know from quantitative analysis of the EDXS profile shown in
That is, the first part P1, which is an interface between the substrate and the first NiSi film (SF1), has NiSi1-xGex and the second part P2 has mainly NiSi.
The germanium distribution curve (∘) of
On the other hand, in an actual process of manufacturing a semiconductor device, an interlayer insulating layer reflow is performed in order to form an interlayer insulating layer after forming a silicide film such as the first NiSi film (SF1) or the second NiSi film (SF2). The reflow process requires annealing process, which takes longer and requires a higher temperature than the process of forming the first NiSi film (SF1) or the second NiSi film (SF2).
In order for a semiconductor device formed with the first NiSi film (SF1) or the second NiSi film (SF2) to have better performance than a semiconductor device formed with the NiSi of the prior art, it needs to secure the thermal stability of the first NiSi film (SF1) and the second NiSi film (SF2) for a subsequent high temperature process such as the reflow process.
Experiments used to test the thermal stability of the first NiSi film (SF1), the second NiSi film (SF2) and the NiSi of the prior art during a subsequent high temperature process will now be described.
First, the NiSi of the prior art, the first NiSi film (SF1), and the second NiSi film (SF2) were formed by RTA for 30 seconds at a temperature of 550° C. After each NiSi film was formed, Ni that had not reacted was removed.
Then, the NiSi of the prior art, the first NiSi film (SF1), and the second NiSi film (SF2) were annealed at four temperatures, 550° C., 600° C., 650° C., and 700° C., each for 30 seconds. The annealing process was performed in a tube furnace under the nitrogen gas atmosphere. Every time the annealing at each temperature was completed, the sheet resistances of the NiSi of the prior art, the first NiSi film (SF1), and the second NiSi film (SF2) were measured.
As the annealing temperatures of the NiSi of the prior art, the first NiSi film (SF1), and the second NiSi film (SF2) increase, the sheet resistance (∘) of the NiSi of the prior art increases, whereas the sheet resistances (Δ, ∘) of the first NiSi film (SF1) and the second NiSi film (SF2) are lower than and increase slower than the sheet resistance (∘) of the NiSi of the prior art. In particular, when the annealing temperature reaches 700° C., the sheet resistance (∘) of the NiSi of the prior art rapidly increases, whereas the sheet resistances (Δ, ∘) of the first NiSi film (SF1) and the second NiSi film (SF2) do not change much.
Such results indicate that the thermal stability of the first NiSi film (SF1) and the second NiSi film (SF2) in the annealing process is much higher than that of the NiSi of the prior art.
Also, in comparison with the thermal stability of the first NiSi film (SF1) and the second NiSi film (SF2) in
A method of manufacturing a semiconductor device to which the method of forming a silicide film according to an embodiment of the present invention is applied will now be described.
Referring to
As shown in
The product obtained after the germanium film 46 and the nickel film 48 are sequentially formed is RTA-processed under the same condition as described above. Since the silicide reaction occurs only in a material film including silicon, a nickel silicide reaction selectively occurs in the RTA process in the gate electrode G, the source region S, and the drain region D, where nickel can react with silicon. As shown in
An example in which the method of forming a silicide film according to an embodiment of the present invention is applied to a method of manufacturing a semiconductor memory device will now be described.
Referring to
A method of forming a silicide film according to an embodiment of the present invention may be applied to a memory device other than the semiconductor memory device as shown in
As described above, in a method of forming a silicide film according to an embodiment of the present invention, a Ge film is interposed between a Ni film and a substrate including silicon to form a NiSi film during an annealing process. A semiconductor device having a low sheet resistance and excellent thermal stability can be manufactured using the NiSi film. When the method of forming a silicide film is applied to a semiconductor device, a semiconductor memory device, or a next-generation device, a device with high quality can be effectively manufactured and the performance of the device can be maximized to improve competitiveness of the goods.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, the thickness of the NiSi film according to the location where the NiSi film is formed and the thickness of the germanium film can be varied by a person skilled in the art. The method of forming a silicide film may be applied to a method of manufacturing a transistor other than MOSFET. Therefore, various changes in form and details may be made to the description herein without departing from the spirit and scope of the present invention as defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-86509 | Dec 2003 | KR | national |
