CN100517636C - Shallow plough groove isolation structure forming method - Google Patents
Shallow plough groove isolation structure forming method Download PDFInfo
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- CN100517636C CN100517636C CNB2006101191478A CN200610119147A CN100517636C CN 100517636 C CN100517636 C CN 100517636C CN B2006101191478 A CNB2006101191478 A CN B2006101191478A CN 200610119147 A CN200610119147 A CN 200610119147A CN 100517636 C CN100517636 C CN 100517636C
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Abstract
The invention discloses a shallow groove isolation forming method and a shallow groove separation structure thereof; the method comprises the following procedures: an underlay with an groove opening on the surface is provided; the underlay is put to a high-density plasma chemical vapor deposition chamber; reaction gas and hydrogen gas are guided to the chamber; at the same time, the chamber is controlled by pressure; the underlay is taken out. In the shallow groove isolation structure formed by the forming method of the invention, the hydrogen content in the underlay is a fixed value and does not change along the production batch, thereby increasing the stability of the grid oxide layer thickness of the device between batches and improving the consistency of device performance between the batches.
Description
Technical field
The present invention relates to technical field of manufacturing semiconductors, particularly a kind of shallow trench isolation from formation method and fleet plough groove isolation structure.
Background technology
Often utilize the insulation between shallow trench isolation technology (STI, Shallow TrenchIsolation) realization circuit element to isolate in the modern integrated circuits technology.So-called shallow trench isolation technology is to form an opening by corrosion on Semiconductor substrate, deposits this opening of one deck filling insulating material again and forms shallow trench, and then the technology of isolating between the realization device.Usually the insulating material of filling groove is to utilize chemical vapour deposition (CVD) (CVD, Chemical Vapor Deposition) method to form.Yet, along with constantly dwindling of feature sizes of semiconductor devices, area of isolation between the device is also corresponding thereupon to be dwindled, in making, technology often need fill to realize the isolation between device a vertical wide bigger groove, at this moment, general CVD technology can in groove, form in filling process the space, filling second-rate.
Application number is that 97116168.2 Chinese patent application proposes to utilize high density plasma chemical vapor deposition (HDP, High density plasma) method is filled vertical wide bigger groove, this method can effectively reduce traditional CVD method filling the high vertical wide space that is prone to during than groove, improves the effect of filling.
Figure 1A to 1C is the device architecture profile of the existing sti structure forming process of explanation, Figure 1A is the device architecture profile behind the formation sti trench channel opening, shown in Figure 1A, at first, the buffer oxide layer 102 of deposition growing skim on substrate 101, then, deposition stops layer 103, and its material is generally SiN.Then, pattern is isolated in photoetching, and is that mask is to SiN layer 103, SiO to photoresist
2 Layer 102 and substrate 101 carry out etching, form sti trench channel opening 104.
Figure 1B is the device architecture profile behind the filling groove opening, shown in Figure 1B, deposits the insulating barrier 105 of a bed thickness according to pattern on substrate, as SiO
2Layer, this insulating barrier can be used as filler and is packed in the groove opening 104.For vertical wide bigger groove, often utilize the HDP method to realize the filling in this step.Wherein, for improving filling effect, in filling process, can add the H plasma usually.
Fig. 1 C is for forming the device architecture profile behind the sti structure, shown in Fig. 1 C, filler 105 carried out planarization after, that removes substrate 101 surfaces stops layer and buffering oxide layer, has formed shallow trench isolation from (STI) structure in substrate.
After forming fleet plough groove isolation structure, what carry out usually is the making of device grids structure, grow earlier gate oxide and grid material, and photoetching again, etching are to form grid.
But, find aborning, when utilizing the HDP method to fill the groove of sti structure, can make the gate oxide thickness of device fluctuation occur.Fig. 2 is the test result schematic diagram of the gate oxide thickness of the device of the existing method making of employing sti structure, as shown in Figure 2,201 for testing the gate oxide thickness situation of change of the PMOS device that obtains among the figure, 202 for testing the gate oxide thickness situation of change of the nmos device that obtains, can see, no matter PMOS or nmos device, the thickness of its gate oxide all presents a kind of fluctuation situation that changes by some cycles, rule, and the scope of its thickness fluctuation reaches
As everyone knows, gate oxide thickness is most important to the performance of device, and a plurality of important parameters of device all can be subjected to the influence of gate oxide thickness, as device threshold voltage, drain saturation current, grid capacitance, device thermal stability, reliability or the like.Especially after device size further dwindles, it is thinner that gate oxide becomes, the variation of its thickness is bigger to the influence of device, at this moment, the situation that device performance changes along with gate oxide thickness can be sensitiveer, therefore, must give above-mentioned because of adopting the HDP method to fill the regular enough attention of problem that change of gate oxide thickness that the sti trench groove causes, strive for improving the stability of the gate oxide thickness of device, and then guarantee the consistency of device performance.
Summary of the invention
The invention provides a kind of shallow trench isolation from the formation method, the hydrogen content in the substrate of the fleet plough groove isolation structure that is formed by this method is a fixed amount, can improve adopt existing component grid oxidizing layer thickness batch with batch between generation than the problem of great fluctuation process.
A kind of shallow trench isolation provided by the invention from the formation method, comprise step:
Provide a surface to have the substrate of groove opening;
Described substrate is put into the high density plasma chemical vapor deposition chamber;
In described chamber, introduce reacting gas and hydrogen, simultaneously, described chamber is carried out pressure control;
Take out described substrate.
Wherein, the excursion with described pressure is controlled in the 0.15mTorr.
Wherein, described pressure control is to realize by the opening degree of regulating the automatic pressure adjuster valve, and described pressure is arranged between 10 to 15mTorr.
Wherein, described reacting gas comprises silane and oxygen.
Wherein, the degree of depth of described groove opening be 3000 to
Wherein, the flow of described hydrogen is between 800 to 1500sccm.
The present invention has a kind of fleet plough groove isolation structure of identical or relevant art feature, comprises the filler in substrate, the groove opening that forms on described substrate and the described groove opening, and wherein, the hydrogen content in the described substrate is a fixed value.
Wherein, described filler is silica or silicon oxynitride, and this filler is formed by the high density plasma chemical vapor deposition method.
Compared with prior art, the present invention has the following advantages:
Shallow ridges groove forming method of the present invention, by the HDP chamber pressure in traditional packed layer forming process is controlled, make when carrying out trench fill, diffusion depth and the residual dosage basically identical of hydrogen (H) plasma in the wafer of each batch in the chamber, promptly, hydrogen content in the substrate of the fleet plough groove isolation structure that is formed by the inventive method is a fixed amount, the growth rate of guaranteeing gate oxide subsequently can remain unchanged between criticizing and criticizing substantially, improved batch and batch between the stability of gate oxide thickness of device, improved batch with criticize between the consistency of device performance.
Description of drawings
Figure 1A to 1C is the device architecture profile of the existing sti structure forming process of explanation;
Fig. 2 is the test result schematic diagram of the gate oxide thickness of the device of the existing method making of employing sti structure;
Fig. 3 is in the existing HDP filling process, the situation of change schematic diagram of chamber pressure;
Fig. 4 is the device profile schematic diagram of hydrogen ion spread condition in the explanation HDP filling process;
Fig. 5 is the flow chart of shallow trench isolation of the present invention from the specific embodiment of formation method;
Fig. 6 is in the HDP filling process of the present invention, the situation of change schematic diagram of chamber pressure;
Fig. 7 is the test result schematic diagram of the gate oxide thickness of the device of employing the inventive method making sti structure.
Embodiment
For above-mentioned purpose of the present invention, feature and advantage can be become apparent more, the specific embodiment of the present invention is described in detail below in conjunction with accompanying drawing.
Processing method of the present invention can be widely applied in many application; and can utilize many suitable material; be to be illustrated below by preferred embodiment; certainly the present invention is not limited to this specific embodiment, and the known general replacement of one of ordinary skilled in the art is encompassed in protection scope of the present invention far and away.
Secondly, the present invention utilizes schematic diagram to describe in detail, when the embodiment of the invention is described in detail in detail, for convenience of explanation, the profile of expression device architecture can be disobeyed general ratio and be done local the amplification, should be with this as limitation of the invention, in addition, in the making of reality, should comprise the three dimensions size of length, width and the degree of depth.
Solve the situation of the gate oxide thickness cyclic fluctuation that occurs in the element manufacturing, at first will analyze the cause that this kind situation occurs.After the process lot of experiment validation, the pressure oscillation situation of the HDP chamber when finding the thickness fluctuation situation of this gate oxide and filling shallow trench is closely similar.Fig. 3 is in the existing HDP filling process, the situation of change schematic diagram of chamber pressure, 301 is the change curve of HDP chamber pressure among the figure, 301 among 201,202 in the comparison diagram 2 and Fig. 3, as can be seen, three's period of change, Changing Pattern are on all four.
Why 301 change curves shown in Fig. 3 appear in the pressure of HDP chamber in the trench fill process, be to form thin film in the HDP chamber simultaneously because the film growth of each batch wafer all can make, stain for preventing particle, keep film growth quality preferably, some batches of wafer growths of every process, as 4 batches, will carry out an automatically cleaning to the HDP chamber and handle, to remove the film that adheres in the chamber.Therefore, the variation of the regularity in cycle has just appearred being spaced apart with automatically cleaning in the environment in the HDP chamber, and the variation of this environment makes the pressure correspondence in the HDP chamber situation of change shown in Figure 3 occur.
In the filling process of sti trench groove, can add hydrogen usually, form the H plasma, to reach better filling effect.This H plasma can diffuse in the substrate in filling process, Fig. 4 is the device profile schematic diagram of hydrogen ion spread condition in the explanation HDP filling process, can see, because of the H ion volume little, in light weight, has bigger mean free path, it can spread in substrate in filling process, and it can pass the buffer oxide layer 102 that is covered on the silicon substrate 101 and stop layer 103, arrives in the silicon substrate 101.Therefore, stop layer 103 and buffering oxide layer 102 even after trench fill, removed, still have section H ion 410 and remain in the silicon substrate 101, and how much this residual quantity is the influence of the degree of depth (mean free path of H ion in other words) that spread in the HDP filling process by the H ion.In addition, because the diffusion depth of H ion (or mean free path) is and cavity indoor pressure proportional (λ ∝ 1/P), can release, the fluctuation situation of change shown in 301 among similar Fig. 3 also can appear in the diffusion depth (or dosage) of H ion in wafer (silicon substrate 101).
After trench fill is finished, removed stop the layer and the buffering oxide layer, what carry out then is the growth of gate oxide.Notice in the growth of gate oxide, the H ion can be used as catalyst and uses, therefore, the front remains in the growth rate that how much will inevitably have influence on this step gate oxide of the H ion dose in the silicon substrate in the HDP filling process, H ion residues amount (is that diffusion depth is bigger more for a long time in silicon substrate, when the HDP cavity indoor pressure is big in other words), the growth rate of gate oxide can be very fast, causes its growth thickness bigger; Otherwise, in silicon substrate H ion residues amount more after a little while, the growth rate of gate oxide can be slower, its growth thickness is also just thinner.Therefore, finally show as shown in Figures 2 and 3, the actual growth thickness of gate oxide changes along with the variation of HDP chamber pressure.
In sum, improve the stability of gate oxide thickness, just must improve the stability of HDP filling process middle chamber internal pressure.For this reason, the present invention has added the step that the pressure of chamber is controlled when groove being carried out the HDP filling.Fig. 5 is the flow chart of shallow trench isolation of the present invention from the specific embodiment of formation method, introduces shallow trench isolation of the present invention in detail from forming process below in conjunction with Fig. 5.
At first, the substrate (S501) that provides a surface to have groove opening also has buffer oxide layer and the layer that stops that being used to provide grinding endpoint usually on this substrate.Then, this substrate is put into high density plasma chemical vapor deposition chamber (S502).
Then, introduce reacting gas and hydrogen (S503) in described chamber, this reacting gas and hydrogen form plasma in chamber, to form packed layer filling groove opening on substrate, simultaneously, chamber have been carried out pressure control (S504).In the present embodiment, the degree of depth of this groove opening 3000 to
Between, as be
Or
Deng.And having adopted silica is that packing material is filled groove opening, and at this moment, the reacting gas of introducing in the chamber can be silane and oxygen etc.In addition, in order to improve filling quality, its interior pore volume that produces when reducing trench fill, in filling process, also in chamber, add hydrogen, form hydrogen plasma, in the present embodiment, the amounts of hydrogen that adds can be between 800 to 1500sccm, as are 1000sccm, 1200sccm etc.In existing this HDP filling process, be do not carry out chamber pressure controlled, therefore, the fluctuation range of the pressure in the HDP chamber is bigger, shown in 301 curves among Fig. 3, its fluctuation range has reached 0.5mTorr, and this bigger pressure oscillation meeting causes that the obvious fluctuation of the gate oxide thickness of back changes, and then causes device performance fluctuation to occur.For avoiding this situation to take place, in the present embodiment, this step HDP filling process has been carried out the monitoring of chamber pressure, suppose the pressure value of setting is determined between 10 to 15mTorr, as be 12mTorr.In the HDP filling process, utilize the pressure inductor test to obtain the interior pressure test value of chamber, relatively obtain the difference between this pressure test value and the pressure value of setting again, and regulate the opening degree of automatic pressure adjuster valve, can realize automatic control cavity indoor pressure according to this difference.After adding pressure control, it is stable that cavity indoor pressure can keep substantially, and its fluctuation range obviously reduces.
Fig. 6 is in the HDP filling process of the present invention, the situation of change schematic diagram of chamber pressure, and as shown in Figure 6,601 for adding the pressure history of the HDP chamber after pressure is controlled among the figure.Can see, after adding pressure control, the situation that the chamber pressure of originally representing among Fig. 3 without when control can change with the automatically cleaning cycle of HDP chamber no longer exists, and the excursion of cavity indoor pressure has been reduced in the 0.15mTorr by original 0.5mTorr.
After finishing the deposition of packed layer, take out substrate (S505), finish the deposition of shallow trench packed layer.Then, packed layer is carried out planarization, removal stops layer and buffering oxide layer.Can carry out the growth of gate oxide with that.Because the front is controlled the pressure in the HDP chamber, realized the fluctuation range of its pressure is limited in the 0.15mTorr, in this step HDP filling process, spreading and remain in the interior H content of substrate also will be relatively stable.Therefore, in the back in the growth course of the gate oxide that carries out, H ion dose relatively stable that this influences its growth rate can make the fluctuation of growth thickness of this gate oxide diminish.That is, along with the raising of HDP chamber pressure stability, the consistency of the gate oxide thickness of the device between criticizing and criticizing makes moderate progress.
Fig. 7 is the test result schematic diagram of the gate oxide thickness of the device of employing the inventive method making sti structure, 701 for after controlling the HDP chamber pressure among the figure, the situation of change of the gate oxide thickness of the device that test obtains, as can be seen from Figure, after the HDP chamber pressure is stable, it is stable that the thickness of gate oxide also becomes, by among Fig. 2
Scope in the fluctuation, become among Fig. 7
Scope in the fluctuation.The raising of the stability of this gate oxide thickness between criticizing and criticizing, the performance of the device between feasible the criticizing and criticizing of producing is uniformity more.
In order to verify that fill method of the present invention can not influence the film quality of the packed layer of formation, the HDP film is tested, the result of table 1 for adopting pressure control front and back that the HDP film is tested, as shown in table 1, carrying out pressure control front and back, the pressure variety in the chamber is reduced to 0.16mTorr by 0.45, and variable quantity obviously reduces, when this carried out growth of gate oxide layer for the back, the gate oxide that forms the thickness uniformity was favourable.In addition, can see that the filled with film that utilizes the inventive method to form still is all not have big variation aspect the refractive index at stress, thickness, can think that the film that adopts the inventive method to form still can satisfy the requirement that technology is made qualitatively.
In the present embodiment, the material of filling in the groove is a silica material, and in other embodiments of the invention, this filler can also be other materials such as silicon oxynitride, silicon nitride, as long as when utilizing HDP deposition filler, in chamber, introduce corresponding reacting gas and get final product.
Shallow trench isolation of the present invention is from the formation method, by the pressure of HDP chamber is controlled, stablized batch and batch between diffuse into H content in the substrate, and then make batch with criticize between the gate oxide thickness uniformity more of device, improved the consistency of device performance.
Table 1
The fleet plough groove isolation structure that utilizes shallow trench isolation of the present invention to form from the formation method, comprise substrate, at groove opening that forms on the substrate and the filler in groove opening, wherein, the hydrogen content in the substrate is a fixed value, not can along with produce batch and change.Fleet plough groove isolation structure of the present invention, used filler are silica or silicon oxynitride, and it is to be formed by the high density plasma chemical vapor deposition method.
Adopt method of the present invention that the high density plasma CVD chamber has been carried out pressure control, make that the hydrogen content that diffuses in the substrate is a fixed amount in the filler deposition process, the growth rate of guaranteeing gate oxide subsequently can remain unchanged substantially, improved batch and batch between the stability of gate oxide thickness of device, improved batch with criticize between the consistency of device performance.
Though the present invention with preferred embodiment openly as above; but it is not to be used for limiting the present invention; any those skilled in the art without departing from the spirit and scope of the present invention; can make possible change and modification, so protection scope of the present invention should be as the criterion with the scope that claim of the present invention was defined.
Claims (7)
1, a kind of shallow trench isolation from the formation method, comprise step:
Provide a surface to have the substrate of groove opening;
Determine the thickness fluctuation allowed band of the gate oxide of device to be formed on the described substrate; Described substrate is put into the high density plasma chemical vapor deposition chamber;
Determine the pressure oscillation allowed band of described high density plasma chemical vapor deposition chamber according to described thickness fluctuation allowed band;
In described chamber, introduce reacting gas and hydrogen, simultaneously, described chamber is carried out pressure control, with the consistency of the gate oxide thickness that improves subsequent growth according to described pressure oscillation allowed band;
Take out described substrate.
2, formation method as claimed in claim 1 is characterized in that: described pressure oscillation allowed band is in 0.15mTorr.
3, formation method as claimed in claim 1 is characterized in that: described pressure control is to realize by the opening degree of regulating the automatic pressure adjuster valve.
4, formation method as claimed in claim 1, it is characterized in that: described pressure is arranged between 10 to 15mTorr.
5, formation method as claimed in claim 1, it is characterized in that: described reacting gas comprises silane and oxygen.
6, formation method as claimed in claim 1 is characterized in that: the degree of depth of described groove opening is 3000 to 6000
7, formation method as claimed in claim 1, it is characterized in that: the flow of described hydrogen is between 800 to 1500sccm.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101191478A CN100517636C (en) | 2006-12-05 | 2006-12-05 | Shallow plough groove isolation structure forming method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101191478A CN100517636C (en) | 2006-12-05 | 2006-12-05 | Shallow plough groove isolation structure forming method |
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| CN101197306A CN101197306A (en) | 2008-06-11 |
| CN100517636C true CN100517636C (en) | 2009-07-22 |
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Effective date of registration: 20111109 Address after: 201203 Shanghai City, Pudong New Area Zhangjiang Road No. 18 Co-patentee after: Semiconductor Manufacturing International (Beijing) Corporation Patentee after: Semiconductor Manufacturing International (Shanghai) Corporation Address before: 201203 Shanghai City, Pudong New Area Zhangjiang Road No. 18 Patentee before: Semiconductor Manufacturing International (Shanghai) Corporation |
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Granted publication date: 20090722 Termination date: 20181205 |