Background technology
At present, be accompanied by the develop rapidly of semiconductor fabrication, semiconductor device is in order to reach arithmetic speed faster, bigger memory data output and more function, wafer develops towards higher component density, high integration direction, the manufacturing technology of semiconductor device has entered 65nm and even 45nm process node, and the minimum feature size of grid width has reached 45nm or littler.
And in the manufacturing process of complementary metal oxide semiconductors (CMOS) (CMOS) device, some technological processes will be to the performance of metal oxide semiconductor field effect tube (MOSFET), particularly the performance of p NMOS N-channel MOS N (PMOS) core parts causes bigger influence, thereby makes the performance of formed semiconductor components and devices also decrease.
Fig. 1 is the flow chart that forms the method for PMOS in the prior art, and Fig. 2 A~2G is the schematic diagram that forms the method for PMOS in the prior art.In the prior art, the method for formation PMOS comprises step as described below:
Step 101 forms gate oxide and polysilicon layer successively on substrate.
Shown in Fig. 2 A, in this step, will at first on substrate 1, form gate oxide 2, and then on gate oxide 2, deposit a polysilicon layer 3.
Step 102 is carried out etching to described gate oxide and polysilicon layer, forms grid.
Shown in Fig. 2 B, in this step, will expose, technology such as etching, thereby form grid 301 above-mentioned polysilicon layer 3 and gate oxide 2.
Step 103 forms first side wall (Offset Spacer) in the both sides of described grid.
Shown in Fig. 2 C, in this step, will form first side wall 4 in the both sides of grid 301, described first side wall 4 is generally formed by silica/silicon nitride medium film combinations.The purpose of this first side wall 4 that forms is to reserve certain distance into the shallow ion injection region horizontal proliferation in follow-up rapid thermal annealing (RTA) technology, thereby the raceway groove of guaranteeing grid 301 belows has certain width, with the short-channel effect of avoiding follow-up shallow ion injection technology to be brought, cause channel width to narrow down and the situation of (punch through) phenomenon and leakage current occurs puncturing.
Step 104 is carried out the shallow ion injection technology, to form shallow doped drain (LDD, Lightly DopedDrain) district.
Shown in Fig. 2 D, in this step, will be mask with first side wall 4 and grid 301, carry out the shallow ion injection technology, thereby on substrate 1, form shallow doped drain (LDD, Lightly Doped Drain) district 5.
After carrying out above-mentioned shallow ion injection technology, also can carry out follow-up rapid thermal anneal process (for example, laser annealing technique etc.), make the horizontal proliferation of shallow ion injection region, help the formation of shallow doped drain 5; In addition, above-mentioned rapid thermal anneal process can also be repaired lattice impaired when carrying out the shallow ion injection technology, and can make the ion distribution of being injected more even.
Step 105 forms second side wall in the outside of above-mentioned first side wall.
Shown in Fig. 2 E, in this step, will form second side wall 6 in the outside of first side wall 4 by series of process flow processs such as deposition, photoetching, corrosion.
Step 106 is carried out the deep/source drain extensions ion implantation technology.
Shown in Fig. 2 F, in this step, will be mask, and, carry out the deep/source drain extensions ion and inject, formation source on substrate 1/leakage (S/D) district 7 with second side wall, 6 defined windows with grid 301, first side wall 4 and second side wall 6.
In above-mentioned deep/source drain extensions ion implantation technology, generally be divided into three the step finish, in order to distinguish this three secondary ions injection process, the first time in this step of source/drain region ion can be injected and be called IMP1, source/drain region ion injects and is called IMP2 for the second time, and source/drain region ion injects and is called IMP3 for the third time.Wherein, in IMP1 and IMP3, employed ion is boron (B, Boron) ion; And in IMP2, employed ion is boron fluoride (BF
2) ion.
After carrying out above-mentioned deep/source drain extensions ion implantation technology, also can (for example carry out follow-up rapid thermal anneal process, laser annealing technique etc.), thereby repair lattice impaired when carrying out the deep/source drain extensions ion implantation technology, and make the ion distribution of being injected more even.
Step 107, remove second side wall after, on formed grid, source and drain region the deposition heavily stressed nitride layer.
Shown in Fig. 2 G, in this step, will remove second side wall 6, then the heavily stressed nitride layer 8 of deposition on formed grid, source and drain region.Wherein, can utilize multiple deposition process of the prior art to form heavily stressed nitride layer 8.
Step 108 is carried out ohmic contact (CT) technology.
In this step, will carry out ohmic contact craft, to form ohmic contact layer (not shown among Fig. 2 G).Specifically, when need carry out ohmic contact craft, can be 100~150 dusts with PVD method deposit thickness earlier
Nickel metal layer, carry out process annealing (annealing temperature is generally about 300 ℃) and high annealing (annealing temperature is generally about 450 ℃) then, the SiNi ohmic contact layer that has the low-resistivity phase with formation.Concrete technical process does not repeat them here.
Step 109 is carried out top-level metallic wiring (MT) technology.
In this step, will carry out the top-level metallic Wiring technique, to form top-level metallic wiring (not shown among Fig. 2 G).Concrete technical process does not repeat them here.
By above-mentioned step 101~109, finally can form required PMOS core devices.
But ion implantation process in the manufacturing process of above-mentioned PMOS and employed RTA technology can reduce the performance of MOSFET usually.For example, when carrying out above-mentioned deep/source drain extensions ion implantation technology, owing to need carry out three secondary ion injection process continuously, the dosage that therefore makes source leakage ion inject easily is too high; Simultaneously, because P type element (for example, the boron ion) fair all smaller, so the ions diffusion speed ratio is very fast, thereby make the density of the ion mixed when the follow-up RTA of carrying out technology, occur overdoping (over-run) phenomenon easily, thereby make and to compare with P type MOSFET (PMOSFET) accordingly with corresponding N type MOSFET (NMOSFET), the saturation current (Idsat) by the formed PMOS core devices of above-mentioned technology and the value of cut-off leakage current (Ioff) will substantially exceed the domain of walker of standard, cause the process window (ProcessWindow) of this PMOS core devices too little, thereby greatly reduce the performance of this PMOS core devices.
Therefore, the process window that how to increase the PMOS core devices is the problem that must pay close attention in the semiconductor fabrication process.
Summary of the invention
The invention provides a kind of method of process window of the PMOS of increase core devices, thereby increase the process window of PMOS core devices, improve the yield of product, save the technology cost.
For achieving the above object, the technical scheme among the present invention is achieved in that
A kind of method that increases the process window of PMOS core devices, this method comprises:
On substrate, form successively after gate oxide and the polysilicon layer, formed polysilicon layer is carried out the ion injection first time;
Described gate oxide and polysilicon layer are carried out etching, form grid, and form first side wall in the both sides of described grid;
Carry out the shallow ion injection technology, forming shallow doped drain, and form second side wall in the outside of above-mentioned first side wall;
Carry out the deep/source drain extensions ion implantation technology; Comprise that in described deep/source drain extensions ion implantation technology source/drain region ion injects and source/drain region ion injection for the second time for the first time;
The heavily stressed nitride layer of deposition on formed grid, source and drain region, and carry out ohmic contact craft and top-level metallic Wiring technique.
When formed polysilicon layer and gate oxide being carried out the first time, ion injected, employed ion is the boron ion;
Wherein, described boron energy of ions interval is: 4~8Kev, the dosage interval of described boron ion is: 10
13~10
14/ cm
2
The source first time in described deep/source drain extensions ion implantation technology/drain region ion injects, and employed ion is a boron fluoride BF2 ion;
Wherein, described boron fluoride energy of ions is: 4~10Kev, the dosage of described boron fluoride ion is: 5 * 10
14~5 * 10
15/ cm2.
The source second time in described deep/source drain extensions ion implantation technology/drain region ion injects, and employed ion is the boron ion;
Wherein, described boron fluoride energy of ions is: 1~3Kev, the dosage of described boron ion is: 10
14~2 * 10
15/ cm
2
This method also further comprises: after carrying out described deep/source drain extensions ion implantation technology, carry out rapid thermal anneal process.
This method also further comprises: after carrying out described shallow ion injection technology, carry out rapid thermal anneal process.
Described rapid thermal anneal process is a laser annealing technique.
A kind of method of process window of the PMOS of increase core devices is provided among the present invention in summary.In the method, because described gate oxide and polysilicon layer are being carried out etching with before forming grid, carry out the primary ions injection process earlier, and in follow-up deep/source drain extensions ion implantation technology, only carry out twice ion implantation process, thereby can increase the process window of PMOS core devices effectively, improve the yield of product, save the technology cost.
Embodiment
The present invention is described in detail below in conjunction with drawings and the specific embodiments.
The invention provides a kind of method of process window of the PMOS of increase core devices, this method deposits successively on substrate and forms after gate oxide and the polysilicon, and described gate oxide and polysilicon layer are being carried out etching with before forming grid, carry out primary ions earlier and inject (IMP) process, and in follow-up deep/source drain extensions ion implantation technology, the dosage of this part ion that has injected is deducted, only carry out twice ion implantation process, thereby reduce the dosage of the injection ion in the deep/source drain extensions ion implantation technology, reduce the overdoping phenomenon effectively, improve the performance of PMOS core devices, improve the yield of product.
Fig. 3 is the flow chart of method of the process window of increase of the present invention PMOS core devices.Fig. 4 A~4G is the schematic diagram of method of the process window of increase of the present invention PMOS core devices.As shown in Figure 3, the method for the process window of increase PMOS core devices of the present invention may further comprise the steps:
Step 301 forms gate oxide and polysilicon layer successively on substrate.
Shown in Fig. 4 A, in this step, will at first on substrate 1, deposit and form gate oxide 2, and then on gate oxide 2, deposit a polysilicon layer 3.Wherein, gate oxide 2 generally is made of silicon dioxide and a spot of nitrogen element.
In addition, can use deposition process commonly used in this area to carry out the deposition of above-mentioned gate oxide and polysilicon layer, the concrete deposition gate oxide and the method for polysilicon layer do not repeat them here.
Step 302 is carried out preceding (poly pre-doping) technology of mixing of polysilicon.
Shown in Fig. 4 A, in this step, will carry out the preceding doping process of polysilicon, promptly above-mentioned formed polysilicon layer 3 is carried out the ion implantation process first time, thereby described polysilicon layer 3 is mixed.After (poly pre-doping) technology of before carrying out above-mentioned polysilicon, mixing, can be under the prerequisite that does not reduce the polysilicon resistance rate, reduce the dosage of the ion that is injected in the follow-up deep/source drain extensions ion implantation technology, thereby reduce the situation of (punchthrough) phenomenon and leakage current to occur puncturing owing to channel width that overdoping causes narrows down.
In order to be different from other ion implantation process in the subsequent step, the ion implantation process first time in this step can be called IMP1.
Wherein, carrying out the first time during ion implantation process, employed ion is boron (B) ion; This boron energy of ions interval is: 4~8Kev, the dosage interval is: 10
13~10
14Individual/square centimeter (is abbreviated as "/cm with unit " individual/square centimeter " usually
2", Hereinafter the same).Preferable, can select in actual applications: the boron energy of ions of being injected is respectively: 4Kev, 5Kev, 6Kev, 7Kev or 8Kev, the dosage of the boron ion that is injected is respectively: 2 * 10
13/ cm
2, 4 * 10
13/ cm
2, 6 * 10
13/ cm
2, 8 * 10
13/ cm
2Or 9 * 10
13/ cm
2
In this step, can use ion injection method commonly used in this area to carry out the preceding doping process of above-mentioned polysilicon, therefore, the specific implementation of doping process does not repeat them here before the above-mentioned polysilicon.
Step 303 is carried out etching to described gate oxide and polysilicon layer, forms grid.
Shown in Fig. 4 B, in this step, will expose, technology such as etching, thereby form grid 301 polysilicon layer after the above-mentioned doping 3 and gate oxide 2.
In this step, can use technologies such as exposure commonly used in this area, etching to form required grid 301, therefore, the specific implementation that forms grid does not repeat them here.
Step 304 forms first side wall in the both sides of described grid.
Shown in Fig. 4 C, in this step, will form first side wall 4 in the both sides of grid 301.The purpose of this first side wall 4 that forms is to reserve certain distance into the shallow ion injection region horizontal proliferation in follow-up rapid thermal annealing (RTA) technology, thereby the raceway groove of guaranteeing grid 301 belows has certain width, with the short-channel effect of avoiding follow-up shallow ion injection technology to be brought, cause channel width to narrow down and the situation of punch-through and leakage current occurs.
In this step, described
first side wall 4 is generally by silica/the silicon nitride medium film combinations forms, and the thickness of described
first side wall 4 is generally
Preferably, the thickness of described
first side wall 4 is
In addition, the method for concrete formation first side wall 4 can be used the method for formation side wall commonly used in this area, does not repeat them here.
Step 305 is carried out the shallow ion injection technology, to form shallow doped drain (LDD) district.
Shown in Fig. 4 D, in this step, will be mask with first side wall 4 and grid 301, carry out the shallow ion injection technology, thereby on substrate 1, form shallow doped drain 5.
After carrying out above-mentioned shallow ion injection technology, also can carry out follow-up rapid thermal anneal process (for example, laser annealing technique etc.), make the horizontal proliferation of shallow ion injection region, help the formation of shallow doped drain 5; In addition, above-mentioned rapid thermal anneal process can also be repaired lattice impaired when carrying out the shallow ion injection technology, and can make the ion distribution of being injected more even.
In addition, in this step, can use ion injection method commonly used in this area to carry out above-mentioned shallow ion injection technology, therefore, the specific implementation of above-mentioned shallow ion injection technology does not repeat them here.
Step 306 forms second side wall 6 in the outside of above-mentioned first side wall.
Shown in Fig. 4 E, in this step, will form second side wall 6 in the outside of first side wall 4 by series of process flow processs such as deposition, photoetching, corrosion.
Wherein, described
second side wall 6 is mainly formed by silica/silicon nitride medium film combinations; And the thickness of described
second side wall 6 is generally
Preferably, the thickness of described
second side wall 6 is
In addition, in this step, can use side wall formation method commonly used in this area to form the second above-mentioned side wall 6, therefore, concrete implementation does not repeat them here.
Step 307 is carried out the deep/source drain extensions ion implantation technology.
Shown in Fig. 4 F, in this step, will be mask, and, carry out the deep/source drain extensions ion and inject, formation source on substrate 1/leakage (S/D) district 7 with second side wall, 6 defined windows with grid 301, first side wall 4 and second side wall 6.
In the present invention, above-mentioned deep/source drain extensions ion implantation technology be divided into two the step finish, promptly after carrying out the source first time/drain region ion implantation process, carry out the source second time/drain region ion implantation process again.For the ease of difference, the source/drain region ion implantation process first time in this step can be called IMP2, source/drain region ion implantation process is called IMP3 for the second time.
Wherein, in IMP2, employed ion is boron fluoride (BF
2) ion; This boron fluoride energy of ions is: 4~10Kev, dosage is: 5 * 10
14~5 * 10
15/ cm
2Preferable, can select in actual applications: the boron fluoride energy of ions of being injected is respectively: 3Kev, 5Kev, 7Kev or 9Kev, the dosage of the boron fluoride ion that is injected is respectively: 6 * 10
14/ cm
2, 8 * 10
14/ cm
2, 1 * 10
15/ cm
2, 2 * 10
15/ cm
2Or 4 * 10
15/ cm
2
In IMP3, employed ion is boron (B) ion; This boron energy of ions is: 1~3Kev, dosage is: 10
14~2 * 10
15Individual/cm
2Preferable, can select in actual applications: the boron energy of ions of being injected is respectively: 1Kev, 2Kev or 3Kev, the dosage of the boron ion that is injected is respectively: 2 * 10
14/ cm
2, 4 * 10
14/ cm
2, 6 * 10
14/ cm
2, 8 * 10
14/ cm
2Or 10
15/ cm
2
After carrying out above-mentioned deep/source drain extensions ion implantation technology, also can (for example carry out follow-up rapid thermal anneal process, laser annealing technique etc.), thereby repair lattice impaired when carrying out the deep/source drain extensions ion implantation technology, and make the ion distribution of being injected more even.
In addition, in this step, can use ion injection method commonly used in this area to carry out above-mentioned deep/source drain extensions ion implantation technology, therefore, the specific implementation of above-mentioned deep/source drain extensions ion implantation technology does not repeat them here.
Step 308, the heavily stressed nitride layer of deposition on formed grid, source and drain region.
Shown in Fig. 4 G, in this step, will on formed grid, source and drain region, deposit heavily stressed nitride layer 8.Wherein, can utilize multiple deposition process of the prior art to form heavily stressed nitride layer 8.
Step 309 is carried out ohmic contact (CT) technology.
In this step, will carry out ohmic contact craft, to form ohmic contact layer (not shown among Fig. 4 G).Specifically, when need carry out ohmic contact craft, can with PVD method deposit thickness be earlier
Nickel metal layer, carry out process annealing (annealing temperature is generally about 300 ℃) and high annealing (annealing temperature is generally about 450 ℃) then, the SiNi ohmic contact layer that has the low-resistivity phase with formation.Concrete technical process does not repeat them here.
Step 310 is carried out top-level metallic wiring (MT) technology.
In this step, will carry out the top-level metallic Wiring technique, to form top-level metallic wiring (not shown among Fig. 4 G).Concrete technical process does not repeat them here.
By above-mentioned step 301~310, finally can form required PMOS core devices.
By the method for the process window of above-described increase PMOS core devices as can be known, in technical scheme provided by the present invention, because deposition forms after gate oxide and the polysilicon successively on substrate, and described gate oxide and polysilicon layer are being carried out etching with before forming grid, carry out primary ions earlier and inject (IMP) process, and in follow-up deep/source drain extensions ion implantation technology, the dosage of this part ion that has injected is deducted, only carry out twice ion implantation process, thereby under the prerequisite that does not reduce the polysilicon resistance rate, reduce the dosage of the ion that is injected in the follow-up deep/source drain extensions ion implantation technology, thereby can reduce the channel width that causes owing to overdoping effectively narrows down and the situation of (punchthrough) phenomenon and leakage current occurs puncturing, improve the yield of product, save the technology cost.
The above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.