Background technology
Along with the development of large-scale integrated circuit technique, observing Moore's Law as the characteristic size of the mos field effect transistor (MOSFET) of si-substrate integrated circuit core devices always and constantly dwindling.But metal-oxide-semiconductor grid medium thickness is more and more less, approach its limit.The gate medium of silicon dioxide, below 10nm thickness time (manufacturing limit of silicon materials is commonly considered as 10 nano-scale linewidths), will occur that tunnel current increases, the problems such as needle pore defect and performance failure reliability variation.In order to address these problems, some integrated circuit research makers have started to explore, and adopt high-k gate dielectric material to replace SiO
2shown good effect, the high k process technique of 45nm of Intel Company is exactly good example, has led people to conduct extensive research high-K gate dielectric material.
In the method for the high-quality High-K dielectric layer of preparation, plasma-enhanced ald (PEALD) is all well and good selection.It is mainly self-limiting growth, can control accurately thickness and the chemical constituent of film, and the film of growth has good uniformity and protect row, and has unique advantage in growth has the structure of high-aspect-ratio.Replace SiO
2become the gate medium of MOSFET device, High-K material must have and SiO
2the character that/Si system is similar, and with current semiconductor fabrication process compatibility.
PEALD method has many advantages, and as accurate THICKNESS CONTROL, impurity content is low, and relatively low technological temperature still has outstanding uniformity on large substrate.PEALD method growing film is by surface reaction and the control of self limiting reaction mechanism, and the growth rate of film is the controlled number of deposition cycles that is formed on mainly, rather than reaction gas flow and temperature.Moreover, PEALD method also has an advantage can carry out exactly plasma treatment film.
But conventional plasma-enhanced technique for atomic layer deposition (PEALD) is not done any other to the substrate of reactive deposition and is processed, and has just cleaned silicon chip surface by simple RCA ablution, is then growing film.Conventionally the film interface layer that the method obtains is very thick, and interface state density is very large, and character is not very excellent.And, due to HfO
2, La
2o
3between contour k oxides and Si substrate, easily form boundary layer, and in film, have a large amount of oxygen rooms, cause equivalent gate oxide thickness cannot be reduced to desired value, the increase of film leakage current, electric property declines.
Summary of the invention
The shortcoming of prior art in view of the above, the object of the present invention is to provide a kind of preparation method of high-K medium film, for solving, the boundary layer producing when prior art is prepared high-K medium film is blocked up, in high-K medium film oxygen room too much cause high-K medium film thickness be difficult to up to standard, leakage current increases, degradation problem under electric property.
For achieving the above object and other relevant objects, the invention provides a kind of preparation method of high-K medium film, at least comprise the following steps:
1) provide a Si substrate or SOI substrate, and adopt H
2sO
4and H
2o
2mixed solution cleans described Si substrate or SOI substrate;
2) adopt RCA ablution to clean described Si substrate or SOI substrate;
3) adopt HF solution to clean described Si substrate or SOI substrate;
4) adopt O plasma to carry out plasma treatment to described Si substrate or SOI substrate;
5) adopt N and H plasma original position to carry out plasma treatment to described Si substrate or SOI substrate, to form oxynitrides passivation layer at described Si substrate or SOI substrate surface;
6) using plasma enhancement mode atomic layer deposition method deposits high-k gate dielectric films on described oxynitrides passivation layer;
7) adopt O plasma original position to carry out plasma treatment to described high-k gate dielectric films.
In the preparation method's of high-K medium film of the present invention step 1) in, adopting volume ratio is 3~5: 1 H
2sO
4, H
2o
2mixed solution cleans described Si substrate or SOI substrate, and scavenging period is 5~15min.
In the preparation method's of high-K medium film of the present invention step 2) in, first adopting volume ratio is 1: 0.5~2: 4~6 NH
3h
2o, H
2o
2, H
2o mixed solution cleans described Si substrate or SOI substrate, and scavenging period is 5~15min, and then adopting volume ratio is Si substrate or SOI substrate described in 0.5%~1.5% HF aqueous cleaning, and scavenging period is 20~40s; Finally adopting volume ratio is 1: 0.5~2: 5~7 HCl, H
2o
2, H
2o solution cleans described Si substrate or SOI substrate, and scavenging period is 5~15min.
In the preparation method's of high-K medium film of the present invention step 3) in, Si substrate or SOI substrate described in the HF aqueous cleaning that volume ratio is 0.5%~1.5% adopted.
Preferably, be 45~75s to the scavenging period of described Si substrate or SOI substrate.
In the preparation method's of high-K medium film of the present invention step 4) in, described Si substrate or SOI substrate are placed in to ALD reaction chamber and are warming up to 160~200 ℃, then pass into O to described ALD reaction chamber
2and add that RF power processes described Si substrate or SOI substrate to produce O plasma.
In the preparation method's of high-K medium film of the present invention step 5) in, after adopting O plasma treatment and original position pass into NH to described ALD reaction chamber
3, then add that RF power processes described Si substrate or SOI substrate to produce N, H plasma, to form oxynitrides passivation layer on its surface.
In the preparation method's of high-K medium film of the present invention step 7) in, pass into O to described ALD reaction chamber
2, then add that RF power processes described high-k gate dielectric films to produce O plasma original position, to reduce the oxygen room in described high-k gate dielectric films.
As the preparation method's of a high-K medium film of the present invention preferred version, described step 6) in the material of high-k gate dielectric films be Al
2o
3, HfO
2, La
2o
3, Gd
2o
3, ZrO
2or the binary of its combination in any or oxide more than binary.
As mentioned above, the preparation method of high-K medium film of the present invention, has following beneficial effect: before the RCA of standard ablution, add H
2sO
4, H
2o
2cleaning step, can remove sample surfaces organic substance, improve the degree of purity of substrate surface.After RCA ablution, again remove surface oxide layer with HF, can effectively reduce film interface layer thickness.Utilize plasma Atomic layer deposition method, adopt original position O
2, NH
3the technology on plasma treatment Si surface, the oxynitrides passivation layer that the one deck of growing between high K dielectric film and Si is very thin, this passivation layer can suppress the growth of boundary layer.Then use the plasma-grown mode high K dielectric film of growing, and original position carries out oxygen plasma post-treatment to described high K dielectric film, reduce the oxygen room in film.This method be conducive to reduce interface resilient coating thickness and interface roughness, suppressed Elements Diffusion between substrate and film, be conducive to reduce equivalent gate oxide thickness.
Embodiment
Below, by specific instantiation explanation embodiments of the present invention, those skilled in the art can understand other advantages of the present invention and effect easily by the disclosed content of this specification.The present invention can also be implemented or be applied by other different embodiment, and the every details in this specification also can be based on different viewpoints and application, carries out various modifications or change not deviating under spirit of the present invention.
Refer to Fig. 1.It should be noted that, the diagram providing in the present embodiment only illustrates basic conception of the present invention in a schematic way, satisfy and only show with assembly relevant in the present invention in graphic but not component count, shape and size drafting while implementing according to reality, when its actual enforcement, kenel, quantity and the ratio of each assembly can be a kind of random change, and its assembly layout kenel also may be more complicated.
As shown in Figure 1, the invention provides a kind of preparation method of high-K medium film, at least comprise the following steps:
As shown in S1 in Fig. 1, first carry out step 1), a Si substrate or SOI substrate are provided, and adopt H
2sO
4and H
2o
2mixed solution cleans described Si substrate or SOI substrate, and particularly, employing volume ratio is 3~5: 1 H
2sO
4, H
2o
2mixed solution cleans described Si substrate or SOI substrate, and scavenging period is 5~15min.
In the present embodiment, adopt the H that volume ratio is 4: 1
2sO
4, H
2o
2mixed solution cleans described Si substrate or SOI substrate, and scavenging period is 5~15min.Certainly, in other embodiments, described volume ratio can be 3: 1 or 5: 1 etc.Because general Si substrate or SOI substrate surface may have organic impurities, this step can be removed the organic substance of described Si substrate or SOI substrate surface, improves the degree of purity of substrate surface.
As shown in S2 in Fig. 1, then carry out step 2), adopt RCA ablution to clean described Si substrate or SOI substrate.
Particularly, first adopting volume ratio is 1: 0.5~2: 4~6 NH
3h
2o, H
2o
2, H
2o mixed solution cleans described Si substrate or SOI substrate, and scavenging period is 5~15min, and then adopting volume ratio is Si substrate or SOI substrate described in 0.5%~1.5% HF aqueous cleaning, and scavenging period is 20~40s; Finally adopting volume ratio is 1: 0.5~2: 5~7 HCl, H
2o
2, H
2o solution cleans described Si substrate or SOI substrate, and scavenging period is 5~15min.
In the present embodiment, first adopting volume ratio is the NH of 1: 1: 5
3h
2o, H
2o
2, H
2o mixed solution cleans described Si substrate or SOI substrate, and scavenging period is 10min, and then adopting volume ratio is Si substrate or SOI substrate described in 1% HF aqueous cleaning, and scavenging period is 30s; Finally adopting volume ratio is HCl, the H of 1: 1: 6
2o
2, H
2o solution cleans described Si substrate or SOI substrate, and scavenging period is 10min.
In another embodiment, first adopting volume ratio is the NH of 1: 0.5: 4
3h
2o, H
2o
2, H
2o mixed solution cleans described Si substrate or SOI substrate, and scavenging period is 5min, and then adopting volume ratio is Si substrate or SOI substrate described in 0.5% HF aqueous cleaning, and scavenging period is 20; Finally adopting volume ratio is HCl, the H of 1: 0.5: 5
2o
2, H
2o solution cleans described Si substrate or SOI substrate, and scavenging period is 5min.
In another embodiment, first adopting volume ratio is the NH of 1: 2: 6
3h
2o, H
2o
2, H
2o mixed solution cleans described Si substrate or SOI substrate, and scavenging period is 15min, and then adopting volume ratio is Si substrate or SOI substrate described in 1.5% HF aqueous cleaning, and scavenging period is 40s; Finally adopting volume ratio is HCl, the H of 1: 2: 7
2o
2, H
2o solution cleans described Si substrate or SOI substrate, and scavenging period is 15min.
As shown in S3 in Fig. 1, then carry out step 3), adopt HF solution to clean described Si substrate or SOI substrate.
Particularly, Si substrate or SOI substrate described in the HF aqueous cleaning that employing volume ratio is 0.5%~1.5%.Preferably, be 45~75s to the scavenging period of described Si substrate or SOI substrate.
In the present embodiment, Si substrate or SOI substrate described in the HF aqueous cleaning that employing volume ratio is 1%.Preferably, be 60s to the scavenging period of described Si substrate or SOI substrate.Certainly, in other embodiments, described volume ratio can be 0.5% or 1.5% etc.Described scavenging period can be 45s or 75s etc., needs to adopt according to demand different schemes.Because can form SiO on Si surface after RCA ablution
2layer, SiO
2layer can have a strong impact on reducing of interfacial layer thickness and leakage current, so again remove surface oxide layer with HF after RCA ablution, therefore, this step can reduce interfacial layer thickness effectively.
As shown in S4 in Fig. 1, then carry out step 4), adopt O plasma to carry out plasma treatment to described Si substrate or SOI substrate.Particularly, described Si substrate or SOI substrate are placed in to ALD reaction chamber and are warming up to 160~200 ℃, then pass into O to described ALD reaction chamber
2and add that RF power processes described Si substrate or SOI substrate to produce O plasma.
As shown in S5 in Fig. 1, then carry out step 5), adopt N and H plasma original position to carry out plasma treatment to described Si substrate or SOI substrate, to form oxynitrides passivation layer at described Si substrate or SOI substrate surface.
Particularly, adopt original position O
2and pass into NH to described ALD reaction chamber
3, keep step 4) in ALD reaction chamber in state constant, pass into NH to it
3gas, then adds that RF power makes its ionization, producing O, N, H plasma is processed described Si substrate or SOI substrate, to form oxynitrides passivation layer on its surface.This passivation layer can suppress the growth of boundary layer.
As shown in S6 in Fig. 1, then carry out step 6), using plasma enhancement mode atomic layer deposition method deposits high-k gate dielectric films on described oxynitrides passivation layer.Particularly, the material of described high-k gate dielectric films is Al
2o
3, HfO
2, La
2o
3, Gd
2o
3, ZrO
2or the binary of its combination in any or oxide more than binary.
In the present embodiment, the material of described high-K gate dielectric film is HfO
2/ La
2o
3film.Certainly, in other embodiments, described high-K gate dielectric film can be also HfO
2/ Al
2o
3film etc.
As shown in S7 in Fig. 1, then carry out step 7), adopt O plasma original position to carry out plasma treatment to described high-k gate dielectric films.
Particularly, pass into O to described ALD reaction chamber
2, then add that RF power processes described high-k gate dielectric films to produce O plasma original position, to reduce the oxygen room in described high-k gate dielectric films.Keep step 6) in the state of ALD reaction chamber constant, pass into O to it
2, then add that RF power processes described high-k gate dielectric films to produce O plasma, to reduce the oxygen room in described high-k gate dielectric films.
In sum, the preparation method of high-K medium film of the present invention added H before the RCA of standard ablution
2sO
4, H
2o
2cleaning step, can remove sample surfaces organic substance, improve the degree of purity of substrate surface.After RCA ablution, again remove surface oxide layer with HF, can effectively reduce film interface layer thickness.Utilize plasma Atomic layer deposition method, adopt original position O
2, NH
3the technology on plasma treatment Si surface, the oxynitrides passivation layer that the one deck of growing between high K dielectric film and Si is very thin, this passivation layer can suppress the growth of boundary layer.Then use the plasma-grown mode high K dielectric film of growing, and original position carries out oxygen plasma post-treatment to described high K dielectric film, reduce the oxygen room in film.This method be conducive to reduce interface resilient coating thickness and interface roughness, suppressed Elements Diffusion between substrate and film, be conducive to reduce equivalent gate oxide thickness.So the present invention has effectively overcome various shortcoming of the prior art and tool high industrial utilization.
Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not for limiting the present invention.Any person skilled in the art scholar all can, under spirit of the present invention and category, modify or change above-described embodiment.Therefore, such as in affiliated technical field, have and conventionally know that the knowledgeable, not departing from all equivalence modifications that complete under disclosed spirit and technological thought or changing, must be contained by claim of the present invention.