Embodiment
For above-mentioned purpose of the present invention, feature and advantage can be become apparent more, below in conjunction with accompanying drawing the specific embodiment of the present invention is described in detail.
Set forth a lot of details in the following description so that fully understand the present invention, implement but the present invention can also adopt other to be different from alternate manner described here, so the present invention has not been subjected to the restriction of following public specific embodiment.
Just as described in the background section, in the high K gate dielectric layer manufacture method of prior art, in order to reduce the dielectric constant of gate openings vertical sidewall gate dielectric layer, need in described gate dielectric layer, inject silicon ion.Yet the injection of described silicon ion may reduce the dielectric property of gate openings bottom gate dielectric layer, or owing to stopping of gate openings packing material makes the gate openings vertical sidewall only have the dielectric constant of the high K gate dielectric layer of part to be lowered.
At the problems referred to above, the present inventor provides a kind of manufacture method of MOS transistor gate dielectric layer.In the method, before filling high-k dielectric material to gate openings, need form sacrifice layer at the vertical sidewall of gate openings, and after high-k dielectric material is filled in conformal, described Semiconductor substrate is carried out annealing in process, described annealing in process makes sacrifice layer and high-k dielectric material react, and forms the mixing dielectric layer that has than low-k, thereby has effectively reduced the parasitic capacitance of metal gates both sides.
With reference to figure 1, show the flow process of the manufacture method of MOS transistor gate dielectric layer of the present invention, comprising:
Execution in step S102 provides Semiconductor substrate, is formed with pseudo-gate dielectric layer and dielectric protection layer on the described Semiconductor substrate, is formed with gate openings in the described dielectric protection layer, and described gate openings makes pseudo-gate dielectric layer expose;
Execution in step S104 forms sacrifice layer on described dielectric protection layer with in the gate openings, described sacrifice layer conformal cover gate opening;
Execution in step S106, the described sacrifice layer of anisotropic etching only keeps the sacrifice layer on the gate openings vertical sidewall;
Execution in step S108 forms high-k dielectric material on described dielectric protection layer with in the gate openings, described high-k dielectric material conformal covers described gate openings;
Execution in step S110 carries out annealing in process to described Semiconductor substrate, makes that the sacrifice layer on the gate openings vertical sidewall mixes dielectric layer with high-k dielectric material reaction formation, and described mixing dielectric layer has the dielectric constant less than high-k dielectric material.
In specific embodiment, described sacrifice layer can adopt semi-conducting material or carbon such as silicon, germanium, SiGe, and described high-k dielectric material comprises HfO
2, HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, Al
2O
3, La
2O
3, ZrO
2Or LaAlO etc., described mixing dielectric layer is formed by sacrifice layer and high-k dielectric material reaction, and is corresponding, and described mixing dielectric layer comprises Hf
xSi
yO
z, Hf
xSi
yO
zH, Hf
uTi
xSi
yO
z, Hf
uTa
xSi
yO
z, Hf
uZr
xSi
yO
z, Si
xAl
yO
z, Hf
xGe
yO
zOr Hf
uSi
xGe
yO
zDeng.Be that Si, high-k dielectric material are HfO with described sacrifice layer
2Be example, described Si and HfO
2The reaction back generates mixes dielectric layer Hf
xSi
yO
z, and described Hf
xSi
yO
zDielectric constant significantly be lower than HfO
2Dielectric constant.
After above-mentioned steps was finished, the dielectric layer in the described gate openings comprised: the high-k dielectric material (being high K gate dielectric layer) of gate openings bottom and the mixing dielectric layer on the gate openings vertical sidewall.Afterwards, also need to continue in described gate openings, to fill the gate metal material, to form metal gates.
Next, in conjunction with specific embodiments, the manufacture method of MOS transistor gate dielectric layer of the present invention is further detailed.
Fig. 2 to Fig. 7 is the generalized section of each production phase of manufacture method of MOS transistor gate dielectric layer of the present invention.
As shown in Figure 2, provide Semiconductor substrate 201, be formed with pseudo-gate dielectric layer 202 and dielectric protection layer 203 on the described Semiconductor substrate 201 successively, described pseudo-gate dielectric layer 202 covers Semiconductor substrate 201 surfaces.Also be formed with gate openings 207 in the described dielectric protection layer 203, described gate openings 207 makes pseudo-gate dielectric layer 202 surfaces of its bottom expose.Optionally, also be formed with clearance wall 205 in the dielectric protection layer 203 of described gate openings 207 both sides, described clearance wall 205 can adopt silicon nitride.
As shown in Figure 3, form sacrifice layer 209 on described dielectric protection layer 203 with in the gate openings 207, described sacrifice layer 209 conformals cover described gate openings 207.Described conformal covers and refers to that the thickness of sacrifice layer 209 is less for the degree of depth and width of gate openings 207, can not fill completely described gate openings 207, makes described gate openings 207 still keep and does not form the preceding similar shape of film.
In specific embodiment, adopt the mode of chemical vapor deposition to form described sacrifice layer 209, described sacrifice layer 209 comprises: semi-conducting material or carbon such as silicon, germanium, SiGe, its thickness is less than or equal to 20 dusts.Preferably, be mixed with protium or fluorine element in the sacrifice layer 209 that adopts silicon to form, the doping content of described protium is 5% to 30%, and the doping content of described fluorine element is 5% to 15%.The protium of described doping or fluorine element can reduce subsequent anneal handle in the reaction difficulty of silicon and high-k dielectric material.
As shown in Figure 4, the described sacrifice layer 209 of anisotropic etching removes on the dielectric protection layer 203 sacrifice layer 209 with gate openings 207 bottoms, only keeps the sacrifice layer 209 on gate openings 207 vertical sidewalls.Described residual sacrifice layer 209 can also strengthen the metal electrode of follow-up formation and the distance between source-drain area, thereby has reduced the grid parasitic capacitance.In addition, the shape of described sacrifice layer 209 can accurately be controlled, thereby has avoided the ion injection mode to form the unsteadiness of dielectric layer with low dielectric constant technology.
After described sacrifice layer 209 anisotropic etchings, the pseudo-gate dielectric layer 202 of gate openings 207 bottoms exposes.Afterwards, remove the pseudo-gate dielectric layer 202 that expose described gate openings 207 bottoms, until exposing described Semiconductor substrate 201 surfaces.In specific embodiment, described pseudo-gate dielectric layer 202 is silica, and adopting concentration is that 1% hydrofluoric acid solution (DHF) removes described pseudo-gate dielectric layer 202, and the reaction time is 3 to 5 minutes.
According to the difference of specific embodiment, can also select not remove described pseudo-gate dielectric layer 202 and directly carry out subsequent technique.
As shown in Figure 5, on described dielectric protection layer 203 with in the gate openings 207, form high-k dielectric material 211, described high-k dielectric material 211 conformal cover gate openings 207.Described high-k dielectric material comprises HfO
2, HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, Al
2O
3, La
2O
3, ZrO
2Perhaps LaAlO.In specific embodiment, the thickness of described high-k dielectric material is less than or equal to 60 dusts.
As shown in Figure 6, described Semiconductor substrate 201 is carried out annealing in process, the sacrifice layer on described gate openings 207 vertical sidewalls and high-k dielectric material 211 reactions form and mix dielectric layer 213, and described mixing dielectric layer 213 is connected with clearance wall 205.Described mixing dielectric layer 213 has the dielectric constant less than high-k dielectric material 211.Adopt semi-conducting material or carbon such as silicon, germanium, SiGe at described sacrifice layer, and described high-k dielectric material adopts HfO
2, HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, Al
2O
3, La
2O
3, ZrO
2Or under the situation of LaAlO, described mixing dielectric layer 213 is formed by sacrifice layer and high-k dielectric material reaction, for example can be Hf
xSi
yO
z, Hf
xSi
yO
zH, Hf
uTi
xSi
yO
z, Hf
uTa
xSi
yO
z, Hf
uZr
xSi
yO
z, Si
xAl
yO
z, Hf
xGe
yO
zOr Hf
uSi
xGe
yO
zDeng.The dielectric constant of the material of the mixing dielectric layer of more than enumerating 213 is all less than the high-k dielectric material of correspondence.
In specific embodiment, described annealing in process adopts short annealing to handle, and reaction temperature is 650 to 850 degrees centigrade, and the reaction time is 1 to 3 minute, and reaction atmosphere is nitrogen.
Because described sacrifice layer only residues on the vertical sidewall of gate openings 207, when described annealing in process, the high-k dielectric material 211 of gate openings 207 bottoms can't change the mixing dielectric layer 213 of low-k into, has also just avoided the decline of the high K gate dielectric layer of the MOS transistor dielectric property of employing the present invention making.
As shown in Figure 7, after forming described mixing dielectric layer 213, continue in described gate openings, to fill up the gate metal material.Afterwards, the described gate metal material of planarization only keeps the gate metal material in the gate openings, and the gate metal material of described reservation namely constitutes metal gates 215.
In specific embodiment, described gate metal material comprises: Ti, Co, Ni, Al or W, or one or more alloy or metal silicide among Ti, Co, Ni, Al, the W.
In different embodiment, before forming described gate metal material, can also in described gate openings, conformal cover the workfunction metal material, described workfunction metal material is used for regulating the threshold voltage of MOS transistor.Described workfunction metal material includes but not limited to TiN, TiAlN, TaN, TaAlN or TaC.
So far, the grid structure that comprises high K gate dielectric layer and metal gates that adopts the present invention to make completes, described metal gates is positioned on the Semiconductor substrate, be formed with high K gate dielectric layer between the bottom of metal gates and Semiconductor substrate, and described metal gates both sides are formed with the mixing dielectric layer with low-k, and described mixing dielectric layer is connected with clearance wall and metal gates respectively.Described mixing dielectric layer has the dielectric constant less than high K gate dielectric layer, thereby has reduced the grid parasitic capacitance.
Though the present invention discloses as above with preferred embodiment, the present invention is defined in this.Any those skilled in the art without departing from the spirit and scope of the present invention, all can do various changes and modification, so protection scope of the present invention should be as the criterion with claim institute restricted portion.