The manufacture method at Split-gate flash memory floating boom tipTechnical field
The present invention relates to field of semiconductor manufacture, particularly relate to a kind of manufacture method of Split-gate flash memory floating boom tip.
Background technology
In current semiconductor industry, integrated circuit (IC) products mainly can be divided into three major types type: analog circuit, digital circuit and DA combination circuit, and wherein memory device is an important kind in digital circuit.In recent years, in memory device, the development of flash memory is particularly rapid.The main feature of flash memory is the information that can keep for a long time when not powering up storing; And have that integrated level is high, access speed is fast, be easy to the advantages such as erasing and rewriting, be thus widely used in the multinomial field such as microcomputer, Automated condtrol.
Please refer to Fig. 1, generalized section when Fig. 1 is preparation Split-gate flash memory floating boom, comprise: substrate 10, formation coupling oxide layer 11, the floating gate layer 20 be formed on coupling oxide layer 11 over the substrate 10, be formed in the side wall 30 on floating gate layer 20 and be formed in the source line (SourcePoly) between side wall 30.Under usual technique, the surface of floating gate layer 20 can form floating boom silicon nitride layer (scheming not shown), when forming floating boom, need first to etch and remove floating boom silicon nitride layer, carry out cleaning again, and then floating gate layer 20 is etched, to form floating boom tip, and then deposition forms tunnel oxide, then forms wordline (WordLine) again.
After etching removes floating boom silicon nitride layer, floating gate layer 20 can expose in atmosphere, and floating gate layer 20 can react with the oxygen in air, and form layer of oxide layer 21, the time of exposure is more of a specified duration, and the thickness of the oxide layer 21 of formation is thicker.In order to remove oxide layer 21; to etch normally floating gate layer 20; the floating boom that forming property is good; carrying out adding a step oxide layer technique in etching technics to floating gate layer 20, (also title punctures technique in usual meeting; BreakThough); the oxide layer 21 being positioned at floating gate layer 20 surface is got rid of, then floating gate layer 20 is etched.But remove the ability of oxide layer 21 due to BreakThough technique to fix, therefore, when floating gate layer 20, to expose the time in atmosphere more of a specified duration, when forming thicker oxide layer 21, after just appearing in oxide layer technique, the phenomenon that oxide layer 21 still remains in addition.
If oxide layer 21 residual thickness is thicker, cause floating gate layer 20 floating boom can be made to there is free foot (FGfooting) when etching and forming floating boom, as shown in dotted line frame in Fig. 2, or floating gate layer 20 is caused to form higher tip, as shown in Fig. 3 dotted line frame when etching and forming floating boom.Above-mentioned two situations all can cause the coupling capacitance between the wordline of floating boom and follow-up formation, thus increase the total coupling capacitance of flash cell, finally cause in programming process, the voltage that source line is coupled on floating boom reduces, the probability that hot electron arrives floating boom diminishes, and causes programming to be lost efficacy.
In order to solve the problem, in prior art, the strict floating gate layer 20 that controls exposes the aerial time, such as, within etching removes floating boom silicon nitride layer and the queuing time (Q-Time) carried out between cleaning is strict controlled in 16 hours, queuing time between etching in cleaning with to floating gate layer 20 is strict controlled within 20 hours, within the queuing time between formation floating boom and tunnel oxide is strict controlled in 36 hours.Thus guarantee that floating gate layer 20 exposes the aerial time can not be long, and then ensure that follow-up BreakThough technique can remove oxide layer 21 completely, the flash memory performance of formation be guaranteed.
But, great live load can be increased to manufacturer on the one hand by strictly controlling queuing time, manual control queuing time also can not ensure that the stand-by period of each product is all consistent on the other hand, in addition, if equipment board goes wrong, then queuing time is uncontrollable, still can impact the yield of product.
Summary of the invention
The object of the present invention is to provide a kind of manufacture method of Split-gate flash memory floating boom tip, the formation of floating boom by the impact exposing the time in atmosphere, can not be guaranteed to form stable floating boom most advanced and sophisticated, ensure the good of flash memory performance.
To achieve these goals, the present invention proposes a kind of manufacture method of Split-gate flash memory floating boom tip, comprise step:
There is provided substrate, described substrate is formed with successively coupling oxide layer, floating gate layer and floating boom silicon nitride layer, described floating gate layer is provided with groove, is formed with side wall inside described groove two, is formed with the source line be connected with described substrate between described side wall;
Etching removes described floating boom silicon nitride layer, exposes described floating gate layer;
Cleaning is adopted to carry out clean to described floating gate layer;
Oxidation processes is carried out to the surface of described floating gate layer, forms protection oxide layer;
Adopt floating boom etching technics to carry out etching to described floating gate layer and form floating boom tip; described floating boom etching technics comprises oxide layer technique, and the reaction time of described oxide layer technique is corresponding with the thickness of described protection oxide layer to guarantee complete for described protection oxide etch.
Further, described oxidation processes adopts oxygen to process described floating gate layer, and the range of flow of described oxygen is 1000sccm ~ 5000sccm.
Further, the pressure range of described oxidation processes is 500mTorr ~ 3000mTorr.
Further, the temperature range of described oxidation processes is 50 DEG C ~ 300 DEG C.
Further, the reaction time range of described oxidation processes is 20s ~ 10min.
Further, after described floating gate layer being carried out to etching and forming floating boom, also step is comprised:
Carry out the presedimentary cleaning of tunnel oxide;
Carry out the deposition of tunnel oxide.
Compared with prior art, beneficial effect of the present invention is mainly reflected in: after removal floating boom silicon nitride layer, oxidation processes is adopted to form one deck protection oxide layer on the surface of floating gate layer, the oxidated layer thickness formed due to oxidation processes is controlled, and floating gate layer and air insulated can be opened, avoid follow-uply forming the uncontrollable oxide layer of thickness due to air oxidation, simultaneously, in follow-up floating boom etching technics, utilize oxide layer technique can remove this even and stable protection oxide layer completely, floating gate layer is well etched, form good floating boom most advanced and sophisticated, thus ensure that the yield of the flash memory of preparation is qualified, functional.
Accompanying drawing explanation
Fig. 1 and Fig. 2 is the structural representation prepared in prior art in floating boom process;
Fig. 3 prepares the schematic diagram that floating boom exists most advanced and sophisticated higher phenomenon in prior art;
Fig. 4 is the flow chart of the manufacture method at Split-gate flash memory floating boom tip in one embodiment of the invention;
Fig. 5 to Fig. 6 is the structural representation prepared in one embodiment of the invention in floating boom process.
Embodiment
Be described in more detail below in conjunction with the manufacture method of schematic diagram to Split-gate flash memory floating boom tip of the present invention, which show the preferred embodiments of the present invention, should be appreciated that those skilled in the art can revise the present invention described here, and still realize advantageous effects of the present invention.Therefore, following description is appreciated that extensively knowing for those skilled in the art, and not as limitation of the present invention.
In order to clear, whole features of practical embodiments are not described.They in the following description, are not described in detail known function and structure, because can make the present invention chaotic due to unnecessary details.Will be understood that in the exploitation of any practical embodiments, a large amount of implementation detail must be made to realize the specific objective of developer, such as, according to regarding system or the restriction about business, change into another embodiment by an embodiment.In addition, will be understood that this development may be complicated and time-consuming, but be only routine work to those skilled in the art.
In the following passage, more specifically the present invention is described by way of example with reference to accompanying drawing.According to the following describes and claims, advantages and features of the invention will be clearer.It should be noted that, accompanying drawing all adopts the form that simplifies very much and all uses non-ratio accurately, only in order to object that is convenient, the aid illustration embodiment of the present invention lucidly.
Please refer to Fig. 4, in the present embodiment, propose a kind of manufacture method of Split-gate flash memory floating boom tip, comprise step:
S100: substrate is provided, described substrate is formed with successively coupling oxide layer, floating gate layer and floating boom silicon nitride layer, described floating gate layer is provided with groove, is formed with side wall inside described groove two, is formed with the source line be connected with described substrate between described side wall;
S200: etching removes described floating boom silicon nitride layer, exposes described floating gate layer;
S300: adopt cleaning to carry out clean to described floating gate layer;
S400: carry out oxidation processes to the surface of described floating gate layer, forms protection oxide layer, and the thickness of this oxide layer does not change with the exposure aerial time;
S500: adopt floating boom etching technics to carry out etching to described floating gate layer and form floating boom tip; described floating boom etching technics comprises oxide layer technique; the reaction time of described oxide layer technique is corresponding with the thickness of described protection oxide layer to guarantee complete for described protection oxide etch; thus ensure the impact not by residual oxidization layer in follow-up floating boom etching process, namely guarantee to form stable floating boom most advanced and sophisticated.
Concrete, please refer to Fig. 5, in the step s 100, substrate 100 is formed with coupling oxide layer 110 usually, described floating gate layer 200 is formed in the surface of described coupling oxide layer 110, described floating boom silicon nitride layer (scheming not shown) is formed in the surface of described floating gate layer 200, as etching mask, wherein, described floating gate layer 200 is provided with groove, groove is formed by first time etching, is formed with side wall 300, is formed with the source line 400 be connected with described substrate 100 between described side wall 300 inside described groove two.
At removal floating boom silicon nitride layer, after exposing described floating gate layer 200, usually adopt wet etching to carry out clean to floating gate layer 200, remove residual floating boom silicon nitride layer.
Come in row reference diagram 5, after floating gate layer 200 being carried out to clean and is complete, oxidation processes is carried out to the surface of described floating gate layer 200, form protection oxide layer 210, wherein, oxidation processes adopts oxygen to process described floating gate layer 200, the range of flow of described oxygen is 1000sccm ~ 5000sccm, such as 3000sccm, the pressure range of described oxidation processes is 500mTorr ~ 3000mTorr, such as 1500mTorr, the temperature range of described oxidation processes is 50 DEG C ~ 300 DEG C, it is such as 250 DEG C, the reaction time range of described oxidation processes is 20s ~ 10min, such as 120s, fix owing to adopting the technological parameter of oxidation processes, therefore protection oxide layer 210 thickness formed also is fixed, and it is controlled, uniformity is also good, after formation protection oxide layer 210, floating gate layer 200 just can with air insulated, follow-up placement also can not continue to form the uncontrollable oxide layer of thickness with air reaction for a long time again, also just without the need to strictly controlling queuing time again, greatly reducing the live load of manufacturing department.
Please refer to Fig. 6; in step S500; adopt floating boom etching technics to carry out etching to described floating gate layer 200 and form floating boom; the etching technics that described floating boom etching technics comprises oxide layer technique and carries out floating boom; wherein; first carry out oxide layer technique protection oxide layer 210 is got rid of, then etch floating gate layer 200 and form floating boom.The reaction time of described oxide layer technique is corresponding with the thickness of described protection oxide layer 210, guarantees to remove described protection oxide layer 210 completely, and owing to protecting the uniformity of oxide layer 210 better, therefore, there will not be residual phenomena.
In the present embodiment, the manufacture method at Split-gate flash memory floating boom tip also comprises step: carry out the presedimentary cleaning of tunnel oxide and the deposition of carrying out tunnel oxide, also can comprise the steps necessary that other form Split-gate flash memory afterwards, those skilled in the art should know other techniques of formation Split-gate flash memory, and therefore not to repeat here.
To sum up, in the manufacture method at the Split-gate flash memory floating boom tip that the embodiment of the present invention provides, after removal floating boom silicon nitride layer, oxidation processes is adopted to form one deck protection oxide layer on the surface of floating gate layer, the oxidated layer thickness formed due to oxidation processes is controlled, and floating gate layer and air insulated can be opened, avoid follow-uply forming the uncontrollable oxide layer of thickness due to air oxidation, simultaneously, in follow-up floating boom etching technics, utilize oxide layer technique can remove this even and stable protection oxide layer completely, floating gate layer is well etched, form good floating boom most advanced and sophisticated, thus ensure that the yield of the flash memory of preparation is qualified, functional.
Above are only the preferred embodiments of the present invention, any restriction is not played to the present invention.Any person of ordinary skill in the field; in the scope not departing from technical scheme of the present invention; the technical scheme disclose the present invention and technology contents make the variations such as any type of equivalent replacement or amendment; all belong to the content not departing from technical scheme of the present invention, still belong within protection scope of the present invention.