CN109659237A - The forming method of flush memory device - Google Patents
The forming method of flush memory device Download PDFInfo
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- CN109659237A CN109659237A CN201910001500.XA CN201910001500A CN109659237A CN 109659237 A CN109659237 A CN 109659237A CN 201910001500 A CN201910001500 A CN 201910001500A CN 109659237 A CN109659237 A CN 109659237A
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/66007—Multistep manufacturing processes
- H01L29/66075—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
- H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
- H01L29/66409—Unipolar field-effect transistors
- H01L29/66477—Unipolar field-effect transistors with an insulated gate, i.e. MISFET
- H01L29/66825—Unipolar field-effect transistors with an insulated gate, i.e. MISFET with a floating gate
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/76—Unipolar devices, e.g. field effect transistors
- H01L29/772—Field effect transistors
- H01L29/78—Field effect transistors with field effect produced by an insulated gate
- H01L29/788—Field effect transistors with field effect produced by an insulated gate with floating gate
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- Condensed Matter Physics & Semiconductors (AREA)
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- Computer Hardware Design (AREA)
- Manufacturing & Machinery (AREA)
- Semiconductor Memories (AREA)
- Non-Volatile Memory (AREA)
Abstract
A kind of forming method of flush memory device, comprising: provide substrate, substrate surface has floating gate layer；Control gate is formed in floating gate layer surface, there is the first opening for exposing floating gate layer in the control gate；The first oxide layer is formed in the side wall of the first opening and positioned at the material layer of the first oxidation layer surface；The material layer is aoxidized, forms the second oxide layer on the control gate surface of first opening sidewalls；Using control gate and the second oxide layer as exposure mask, floating gate layer is etched, until exposing substrate, forms floating gate and the second opening between floating gate；Wordline is formed in the first opening and the second opening.The flush memory device that the method is formed can balance breakdown voltage between control gate and wordline and control gate to the control action of floating gate.
Description
Technical field
The present invention relates to technical field of manufacturing semiconductors more particularly to a kind of forming methods of flush memory device.
Background technique
In current semiconductor industry, IC products can be divided mainly into three categories type: analog circuit, digital circuit
With D/A hybrid circuit, wherein memory is an important kind in digital circuit.And in memory, quick flashing in recent years
The development of memory (Flash Memory, abbreviation flash memory) is especially rapid.Flash memory is mainly characterized by the case where not powered
Storage information can be kept for a long time, and has many advantages, such as that integrated level is high, storage speed is fast, be easy to wipe and rewrite, therefore, micro-
The multinomial field such as machine, automation control is widely used.
Flush memory device mainly includes gate stack (Stack Gate) structure and divides grid (Split Gate) structure, wherein
Grid dividing structure, can be to avoid excessive erasable problem in erasable function due to higher programming efficiency, thus is transported extensively
In the electronic products such as all kinds of smart cards, SIM card, microcontroller, mobile phone.
However, the performance of existing flush memory device is still poor.
Summary of the invention
The technical problem to be solved by the present invention is to provide a kind of forming methods of flush memory device, to improve the property of flush memory device
Energy.
In order to solve the above technical problems, the present invention provides a kind of forming method of flush memory device, comprising: provide substrate, institute
Substrate surface is stated with floating gate layer；Control gate is formed on the surface of the floating gate layer, has in the control gate and exposes floating gate
First opening of layer；The first oxide layer is formed in the side wall of first opening and positioned at the material layer of the first oxidation layer surface；
The material layer is aoxidized, forms the second oxide layer on the control gate surface of first opening sidewalls；With the control gate and
Dioxide layer is exposure mask, etches floating gate layer, until exposing substrate, forms floating gate and the second opening between floating gate；?
Wordline is formed in the first opening and the second opening.
Optionally, the thickness of the material layer are as follows: 150 angstroms~250 angstroms.
Optionally, the material of the material layer includes silicon.
Optionally, the technique for aoxidizing the material layer includes dry oxidation technique and wet process oxidation technology.
It optionally, further include floating gate dielectric layer between the floating gate layer and control gate.
Optionally, the forming method of the floating gate dielectric layer and control gate include: formed on the surface of the floating gate layer it is floating
Gate dielectric material film；Control gate material membrane is formed in the floating gate dielectric material membrane, the surface of the control gate material membrane has
Mask layer, the mask layer is interior to have the mask open for exposing control gate material film surface；In the side wall of the mask open
Form side wall；Using the side wall and mask layer as exposure mask, the control gate material membrane is etched, until exposing floating gate dielectric material
Film forms the control gate, has the first opening in the control gate；First open bottom is removed using wet-etching technology
The floating gate dielectric material membrane in portion forms floating gate dielectric layer until exposing floating gate layer.
Optionally, the floating gate dielectric material membrane includes aoxidizing positioned at the third oxide layer of floating gate layer surface, positioned at third
The nitration case of layer surface and positioned at nitridation layer surface the 4th oxide layer；The material of the third oxide layer includes silica,
The material of the nitration case includes silicon nitride, and the material of the 4th oxide layer includes silica；The wet-etching technology
Parameter includes: that etching agent includes phosphoric acid, sulfuric acid and hydrogen peroxide.
Optionally, also there is the 5th oxide layer between the floating gate layer and substrate；Formed floating gate after, formed wordline it
Before, further includes: the 5th oxide layer of removal second open bottom；Remove the 5th oxide layer of second open bottom
Technique includes: wet-etching technology；The parameter of the wet-etching technology includes: that cleaning agent includes hydrofluoric acid, sulfuric acid and dioxygen
Water.
Optionally, the thickness of first oxide layer are as follows: 60 angstroms~70 angstroms.
Optionally, it is formed after the wordline, further includes: form cap on the wordline surface；Form the nut cap
After layer, the control gate and floating gate of the mask layer and mask layer bottom are removed, is respectively formed first positioned at wordline two sides
Storage unit and the second storage unit.
Compared with prior art, the technical solution of the embodiment of the present invention has the advantages that
In the forming method for the flush memory device that technical solution of the present invention provides, there is opening, described in the control gate
The side wall of opening forms the first oxide layer and material layer.Material layer is set to be converted into oxide layer, the oxide layer by oxidation technology
Thickness it is thicker, then the thickness for the second oxide layer being made of the oxide layer and the first oxide layer is thicker, so that wordline and control
The distance between grid processed are larger, therefore, are conducive to improve the breakdown voltage between control gate and wordline.Simultaneously as material layer
There is the first oxide layer between control gate, when the material layer is oxidized complete, first oxide layer is for slowing down oxygen
Chemical industry skill prevents excessive control gate to be oxidized, and therefore, the thickness for being beneficial to prevent the second oxide layer is blocked up.It is subsequent with control
Grid and the second oxide layer are exposure mask, etch floating gate layer to form floating gate.Since the thickness of the second oxide layer is unlikely to blocked up, then float
The ratio of the size of the size and control gate of grid is unlikely to excessive, is conducive to improve control gate to the control action of floating gate.To sum up,
The flush memory device that the method is formed can balance the control of breakdown voltage and control gate to floating gate between control gate and wordline
Production is used.
Detailed description of the invention
Fig. 1 to Fig. 3 is a kind of structural schematic diagram of flush memory device；
Fig. 4 to Figure 12 is the structural schematic diagram of each step of the forming method of the flush memory device of one embodiment of the invention.
Specific embodiment
As described in background, the performance of flush memory device is poor.
Fig. 1 to Fig. 3 is a kind of structural schematic diagram of flush memory device.
Referring to FIG. 1, providing substrate 100, part 100 surface of substrate has floating gate layer 101, the floating gate layer 101
Surface has floating gate dielectric material membrane 102, and 102 surface of floating gate dielectric material membrane has control gate material membrane 103, the control
The part of the surface of grid material film 103 processed has mask layer 104, has in the mask layer 104 and exposes control gate material membrane 103
Mask open (not marked in figure)；The first oxide layer 105 is formed in the side wall of the mask open.
Referring to FIG. 2, being exposure mask with the mask layer 104 and the first oxide layer 105, the control gate material membrane is etched
103 (see Fig. 1) form control gate 113, tool in the control gate 113 until exposing floating gate dielectric material membrane 102 (see Fig. 1)
There is the first opening 106 for exposing floating gate dielectric material membrane 102；Remove the floating gate dielectric material of first opening, 106 bottoms
Film 102 forms the second opening until exposing floating gate layer 101 in the floating gate dielectric material membrane of first opening, 106 bottoms
(not marked in figure).
Referring to FIG. 3, the side wall in first oxide layer 105, first opening 106 and the second opening forms side wall 107；
It is exposure mask with the side wall 107, mask layer 104 and the first oxide layer 105, etches the floating gate layer 101, until exposes substrate
100 surfaces, form floating gate 111 and the third between the floating gate 111 is open (not marking in figure)；In first opening
106, wordline 108 is formed in the second opening and third opening.
In the forming method of above-mentioned flush memory device, the forming method of the side wall 107 includes: in the mask layer 104,
The side wall shape on the surface and the first oxide layer 105, first opening 106 and the second opening of one oxide layer 105 and floating gate layer 101
At side wall film；The side wall film for removing the surface of the mask layer 104, the first oxide layer 105 and floating gate layer 101, forms the side
Wall 107.The technique for removing the side wall film on 101 surface of the mask layer 104, the first oxide layer 105 and floating gate layer includes that dry method is carved
Etching technique.Form by-product during the dry etch process, the by-product is for protecting the first oxide layer 105, the
The side wall film of the side wall of one opening 106 and the second opening is by excessive removal.In the dry etch process, the by-product
Constantly accumulation, so that the side wall film of the first 106 sidewall bottoms of opening was removed compared with the sidewall film of the first 106 top side walls of opening
It is few, it may be assumed that the side wall 107 that the first 106 top side walls of opening are formed thickness compared with the first 106 sidewall bottom side walls 107 of opening
Thickness is thin.
Also, after forming control gate 113, the floating gate dielectric material membrane 102 of 106 bottoms of the first opening of removal is described
Floating gate dielectric material membrane 102 includes silica.The technique of floating gate dielectric material membrane 102 of 106 bottoms of the first opening of removal includes
Wet processing.Since the material of first oxide layer 105 includes silica, the etching agent in the wet processing makes
First oxide layer 105 reduces along the size being parallel on 100 direction of substrate, so that the atop part of part control gate 113 is sudden and violent
Expose.The easy corner region 1 to be formed and be convex to the first opening 106 that is etched in 113 top of part control gate being exposed.The point
Angular zone 1 makes the thinner of the side wall 107 being subsequently formed.The thinner thickness of the side wall 107, so that wordline 108 and control
Breakdown voltage between grid 113 processed is smaller.
A kind of method improving breakdown voltage between 1 control gate 113 of corner region and wordline 108 includes: increase wedge angle region
The thickness of side wall 107 between 1 control gate 113 of domain and wordline 108.However, increase by 1 control gate 113 of corner region and wordline 107 it
Between side wall 107 thickness so that it is described first opening 106 bottoms and the second opening sidewalls formed side wall 107 thickness it is blocked up,
It is then exposure mask with the side wall 107 and control gate 113, the size for being formed by floating gate 111 is larger, then the floating gate 111 and control
Ratio between grid 113 processed is excessive, is unfavorable for improving control gate 113 to the control action of floating gate 111.
To solve the technical problem, the present invention provides a kind of forming method of flush memory device, comprising: provides substrate, institute
Substrate surface is stated with floating gate layer；Control gate is formed on the surface of the floating gate layer, is had described in exposing in the control gate
First opening of floating gate layer；The first oxide layer is formed in the side wall of first opening and positioned at the material of the first oxidation layer surface
Layer；The material layer is aoxidized, forms the second oxide layer on the control gate surface of first opening sidewalls；With the control gate and
Second oxide layer is exposure mask, etches floating gate layer, until exposing substrate, forms floating gate and the second opening between floating gate；
Wordline is formed in the first opening and the second opening.The flush memory device that the method is formed can balance control gate and wordline
Between breakdown voltage and control gate to the control action of floating gate.
It is understandable to enable above-mentioned purpose of the invention, feature and beneficial effect to become apparent, with reference to the accompanying drawing to this
The specific embodiment of invention is described in detail.
Fig. 4 to Figure 12 is the structural schematic diagram of each step of the forming method of the flush memory device of one embodiment of the invention.
Referring to FIG. 4, providing substrate 200,200 surface of substrate has floating gate layer 201.
The substrate 200 provides technique platform for manufacture flush memory device, and the substrate 200 includes that flash memory area (does not show in figure
Out) and logic device area (not shown), subsequent to form flush memory device in the substrate 200 of flash memory area.To make the flash memory
It is electrically isolated between area and logic device area, using isolation structure (not shown) electricity between the flash memory area and logic device area
Isolation.
The material of the substrate 200 include silicon, germanium, SiGe, silicon carbide, GaAs, gallium indium, silicon-on-insulator, absolutely
Germanium or silicon germanium on insulator on edge body.In the present embodiment, the material of the substrate 200 is silicon.
The floating gate layer 201 provides Process ba- sis to be subsequently formed the floating gate of flush memory device.The formation of the floating gate layer 201
Technique includes chemical vapor deposition process or sputtering technology.The material of the floating gate layer 201 include doped p-type or N-type from
The polysilicon or metal of son.In the present embodiment, the material of the floating gate layer 201 is the polysilicon of doped N-type ion.
It should be noted that in the present embodiment, the manufacturing method of the flush memory device provided is carried out as unit of lot
, it may be assumed that the substrate 200 of single treatment batch.In other embodiments, the manufacturing method of the flush memory device provided is with wafer
(wafer) is unit progress, it may be assumed that a piece of substrate of single treatment.
In the present embodiment, also there is the 5th oxide layer (not shown) between the substrate 200 and floating gate layer 201.
The material of 5th oxide layer includes silica.5th oxide layer is used to stop the electronics in subsequent floating gate.
In the present embodiment, 201 surface of floating gate layer has floating gate dielectric material membrane 202 and is located at floating gate dielectric material
The control gate material membrane 203 on 202 surface of film.
In the present embodiment, the floating gate dielectric material membrane 202 includes: the third oxide layer positioned at 201 surface of floating gate layer
(not shown), the nitration case (not shown) that layer surface is aoxidized positioned at third and the 4th oxygen positioned at nitridation layer surface
Change layer (not shown).The material of the third oxide layer includes silica, and the material of the nitration case includes silicon nitride, institute
The material for stating the 4th oxide layer includes silica.In other embodiments, institute's floating gate dielectric material membrane is the single layer knot of silica
Structure, and the formation process of the floating gate dielectric material membrane includes thermal oxidation technology, atom layer deposition process or chemical vapor deposition
Product technique.
The floating gate dielectric material membrane 202 is for being subsequently formed floating gate dielectric layer, after the floating gate dielectric layer is for being isolated
Continuous floating gate and control gate.
The material of the control gate material membrane 203 includes the polysilicon or metal of doped N-type or P-type ion, described
The formation process of control gate material membrane 203 includes: chemical vapor deposition process or sputtering technology.
The control gate material membrane 203 is for being subsequently formed control gate.
Referring to FIG. 5, the part of the surface in the control gate material membrane 203 forms mask layer 204, the mask layer 204
It is interior that there is the mask open (not marking in figure) for exposing control gate material membrane 203；Side wall is formed in 204 side wall of mask layer
205。
The material of the mask layer 204 includes silicon nitride or titanium nitride.The side wall of the mask layer 204 is used for subsequent shape
At side wall 205.
The forming method of the side wall 205 includes: top surface and side wall the formation side wall film in the mask layer 204；
The side wall film for removing 204 top surface of mask layer forms side wall 205 in the side wall of the mask layer 204.
The material of the side wall film includes silica, the formation process of the side wall film include chemical vapor deposition process,
Physical gas-phase deposition or atom layer deposition process.
The technique for removing the side wall film of 204 top surface of mask layer includes dry etch process.
The side wall 205 and mask layer 204 are for subsequent as the exposure mask for forming control gate.
Referring to FIG. 6, being exposure mask with the side wall 205 and mask layer 204, the control gate material membrane 203 is etched, until
Floating gate dielectric material membrane 202 is exposed, control gate 206 is formed, has in the control gate 206 and expose floating gate dielectric material membrane
202 the first opening 250.
It is exposure mask with the side wall 205 and mask layer 204, the technique for etching the control gate material membrane 203 includes dry method
Etching technics.
Referring to FIG. 7, the floating gate dielectric material membrane 202 (see Fig. 6) of 250 bottoms of removal first opening, forms floating gate
Dielectric layer 207.
The technique for removing the floating gate dielectric material membrane 202 of 250 bottoms of the opening includes wet-etching technology.Using wet process
The meaning that etching technics removes the floating gate dielectric material membrane 202 of initial second control gate, 206 bottom is: resting on floating gate
The surface of layer 201 is easier to, and advantageously reduces the damage to floating gate layer 201.
The parameter of the wet-etching technology includes: that etching agent includes phosphoric acid, sulfuric acid and hydrogen peroxide.
When removing the floating gate dielectric material membrane 202 of first opening, 250 bottoms, due to the material packet of the side wall 205
Silica is included, therefore, the etching agent in the wet processing reduces side wall 205 along the size being parallel on 200 direction of substrate,
So that the atop part of part control gate 206 is exposed.Easily being etched at the top of the part control gate 206 being exposed, it is convex to be formed
To the corner region 11 of the second opening 250.The corner region 11 makes the subsequent material layer deposited in corner region 11 relatively thin.
Referring to FIG. 8, the side wall in first opening 250, side wall 205 and floating gate dielectric layer 207 forms the first oxidation
Layer 220 and the material layer 210 positioned at 220 surface of the first oxide layer.
The material of first oxide layer 220 includes silica, the forming method of first oxide layer 220 include:
The mask layer 204, side wall 205 and 201 surface of floating gate layer and side wall 205 and control gate 206 and floating gate dielectric layer 207
Side wall forms the first oxidation film；First oxidation film on 201 surface of the mask layer 204, side wall 205 and floating gate layer is removed, is formed
First oxide layer 220.
The technique of first oxidation film includes high temperature oxidation process.
The thickness of first oxide layer 220 are as follows: 60 angstroms~70 angstroms.
The effect of first oxide layer 220 includes: in subsequent oxidation technical process, and first oxide layer 220 is used
In preventing excessive control gate 206 to be oxidized, prevent the second oxide layer for being located at the first 250 side walls of opening blocked up, then the control
The size of grid 206 processed and the dimension ratio for the floating gate being subsequently formed are unlikely to too small, are conducive to improve control gate 206 to floating gate
Control action；The a part of first oxide layer 220 as subsequent second oxide layer, second oxide layer are used to form floating
The exposure mask of grid.
The material of the material layer 210 includes polysilicon.The formation process of the material layer 210 includes chemical vapor deposition
Technique, physical gas-phase deposition or atom layer deposition process.Although the corner region 11 to be located at angle region shape
At material layer 210 thinner thickness, still, subsequent layers of material 210 be by oxidation technology formed oxide layer, the oxidation
The thickness of layer is relatively thick, and the oxide layer and the first oxide layer constitute the second oxide layer, therefore, the thickness of the second oxide layer compared with
It is thick.Second oxide layer is used to that subsequent control grid and wordline to be isolated, so that it is apart from each other between subsequent control grid and wordline, because
This, is conducive to improve the breakdown voltage between control gate and wordline.
The material layer 210 with a thickness of 150 angstroms~250 angstroms.The meaning of the thickness of the material layer 210 is selected to be:
If the thickness of the material layer 210, less than 150 angstroms, subsequent oxidation material layer 210 is in the second oxidation of 250 side walls formation that is open
The thickness of layer is still relatively thin, so that the breakdown voltage being able to bear between subsequent control grid and wordline is still smaller；If the material layer
210 thickness is greater than 250 angstroms, so that the thickness in the second oxide layer of 250 formation of opening is thicker, then it is subsequent with the second oxygen
The ratio for changing the size of size and control gate that layer is the floating gate that exposure mask is formed is excessive, is unfavorable for control of the control gate to floating gate.
Referring to FIG. 9, the material layer 210 (see Fig. 8) is aoxidized, in 206 table of control gate of first opening, 250 side walls
The second oxide layer of face 212.
The technique for aoxidizing the material layer 210 (see Fig. 8) includes: dry oxidation technique and wet process oxidation technology.
The material layer 210 forms oxide layer by oxidation technology, so that the thickness of oxide layer is relatively thick, then the oxygen
The thickness for changing the second oxide layer 212 that layer and the first oxide layer 220 (see Fig. 8) are constituted is thicker, be conducive to improve control gate 206 and
Breakdown voltage between subsequent wordline.
Although the thinner thickness of 11 material layer 210 of angle region, the material layer 210 is by aoxidizing work
Skill forms oxide layer, and the thickness of the oxide layer is relatively thick, then the second oxidation being made of the first oxide layer 220 and oxide layer
The thickness of layer 212 is thicker so that the distance between control gate 206 and wordline are farther out, therefore, be conducive to improve control gate 206 with
Breakdown voltage between wordline.
Meanwhile during aoxidizing described material layer 210 (see Fig. 8), due to the material layer 210 and control gate 206
Between have the first oxide layer 220, first oxide layer 220 can prevent excessive control gate 206 to be oxidized, so that institute's shape
At the thickness of the second oxide layer 212 be unlikely to blocked up, then subsequent with the second oxide layer 212 and control gate 206 is exposure mask, etching
Floating gate layer 201, the size of the floating gate of formation are unlikely to excessive, then the dimension ratio of the floating gate size and control gate 206 is unlikely
In excessive, be conducive to improve control gate 206 to the control action of floating gate.
In the present embodiment, only material layer 210 is oxidized.In other embodiments, part control gate is also oxidized.
Referring to FIG. 10, be exposure mask with second oxide layer 212 and control gate 206, etch the floating gate layer 201 (see
Fig. 9), until exposing the top surface of substrate 200, floating gate 215 and the second opening between floating gate 215 are formed (in figure
It does not mark).
It is exposure mask with second oxide layer 212 and control gate 206, the technique for etching the floating gate layer 201 includes dry method
Etching technics.
Since the thickness of the second oxide layer 212 is relatively thin, so that be exposure mask with the second oxide layer 212 and control gate 206,
The size for being formed by floating gate 215 is unlikely to excessive, then the ratio of the size of the size and control gate 206 of the floating gate 215 is not
As for excessive, be conducive to improve control gate 206 to the control action of floating gate 215.
Also, the thickness of second oxide layer 212 is relatively large, be conducive to improve control gate 206 and subsequent wordline it
Between breakdown voltage.
Figure 11 is please referred to, forms tunneling oxide layer 214 on the floating gate 215,212 surface of the second oxide layer；Satisfy described
It wears in second opening and the first opening 250 on 214 surface of oxide layer and forms wordline 213.
It is formed after the floating gate 215, is formed before wordline 213, the forming method further include: removal described second is opened
5th oxide layer of mouth bottom；The technique for removing the 5th oxide layer of second open bottom includes: wet-etching technology；Institute
It includes hydrofluoric acid, sulfuric acid and hydrogen peroxide that the parameter for stating wet-etching technology, which includes: etching agent,.
Since second oxide layer 212 is formed by oxidation technology, so that the second oxide layer 212 is finer and close, the quarter
It is less to the removal amount of the second oxide layer 212 to lose agent, then after the cleaning process, the thickness of second oxide layer 212 compared with
Thickness, then the distance between the control gate 206 and wordline 213 still farther out, therefore, between the control gate 206 and wordline 213 still
It is able to bear biggish breakdown voltage.
The material of the tunneling oxide layer 214 includes silica, and the formation process of the tunneling oxide layer 214 includes chemistry
Gas-phase deposition, physical gas-phase deposition or atom layer deposition process.
The material of the wordline 213 includes polysilicon.
The forming method of the wordline 213 includes: to form wordline material layer on 214 surface of tunneling oxide layer, described
Wordline material layer is full of the second opening and the first opening 250；Planarize satisfying for 204 surface of the wordline material layer and mask layer
Oxide layer 214 is worn, until exposing the top surface of mask layer 204, forms the wordline 213.
Figure 12 is please referred to, forms cap 230 on 213 surface of wordline；It is formed after the cap 230, is removed
The control gate 206 (see Figure 11) of the mask layer 204 (see Figure 11) and 204 bottom of mask layer, floating gate dielectric layer 207 and floating
Grid 215 form the first storage unit (not marking in figure) for being located at 213 two sides of wordline and the second storage unit (in figure not
It marks).
The cap 230 is used for the control gate 206 of subsequent removal exposure mask 204 and 204 bottom of the mask layer, floats
When gate dielectric layer 207 and floating gate 215, protection wordline 213 is injury-free.
The material of the cap 230 includes silica.In the present embodiment, the formation process of the cap 230 is
Thermal oxidation technology.In other embodiments, the formation process of the cap includes chemical vapor deposition process.
Although present disclosure is as above, present invention is not limited to this.Anyone skilled in the art are not departing from this
It in the spirit and scope of invention, can make various changes or modifications, therefore protection scope of the present invention should be with claim institute
Subject to the range of restriction.
Claims (10)
1. a kind of forming method of flush memory device characterized by comprising
Substrate is provided, the substrate surface has floating gate layer；
Control gate is formed on the surface of the floating gate layer, there is the first opening for exposing the floating gate layer in the control gate；
The first oxide layer is formed in the side wall of first opening and positioned at the material layer of the first oxidation layer surface；
The material layer is aoxidized, forms the second oxide layer on the control gate surface of first opening sidewalls；
Using the control gate and the second oxide layer as exposure mask, floating gate layer is etched, until exposing substrate, forming floating gate and being located at
The second opening between floating gate；
Wordline is formed in the first opening and the second opening.
2. the forming method of flush memory device as described in claim 1, which is characterized in that the thickness of the material layer are as follows: 150 angstroms
~250 angstroms.
3. the forming method of flush memory device as described in claim 1, which is characterized in that the material of the material layer includes silicon.
4. the forming method of flush memory device as described in claim 1, which is characterized in that the technique for aoxidizing the material layer includes
Dry oxidation technique and wet process oxidation technology.
5. the forming method of flush memory device as described in claim 1, which is characterized in that between the floating gate layer and control gate also
Including floating gate dielectric layer.
6. the forming method of flush memory device as claimed in claim 5, which is characterized in that the floating gate dielectric layer and control gate
Forming method includes: to form floating gate dielectric material membrane on the surface of the floating gate layer；It is formed and is controlled in the floating gate dielectric material membrane
Grid material film processed, the surface of the control gate material membrane have mask layer, have in the mask layer and expose control grid material
The mask open of film surface；Side wall is formed in the side wall of the mask open；Using the side wall and mask layer as exposure mask, institute is etched
Control gate material membrane is stated, until exposing floating gate dielectric material membrane, the control gate is formed, has first to open in the control gate
Mouthful；The floating gate dielectric material membrane of first open bottom is removed using wet-etching technology, until exposing floating gate layer, is formed
Floating gate dielectric layer.
7. the forming method of flush memory device as claimed in claim 6, which is characterized in that the floating gate dielectric material membrane includes position
In the third oxide layer of floating gate layer surface, positioned at the nitration case of third oxidation layer surface and positioned at the 4th oxygen of nitridation layer surface
Change layer；The material of the third oxide layer includes silica, and the material of the nitration case includes silicon nitride, the 4th oxide layer
Material include silica；The parameter of the wet-etching technology includes: that etching agent includes: phosphoric acid, sulfuric acid and hydrogen peroxide.
8. the forming method of flush memory device as described in claim 1, which is characterized in that also have between the floating gate layer and substrate
There is the 5th oxide layer；It is formed after the floating gate, is formed before wordline, the forming method further include: removal described second is opened
5th oxide layer of mouth bottom；The technique for removing the 5th oxide layer of second open bottom includes: wet-etching technology；Institute
It includes hydrofluoric acid, sulfuric acid and hydrogen peroxide that the parameter for stating wet-etching technology, which includes: etching agent,.
9. the forming method of flush memory device as described in claim 1, which is characterized in that the thickness of first oxide layer are as follows:
60 angstroms~70 angstroms.
10. the forming method of flush memory device as claimed in claim 6, which is characterized in that formed after the wordline, also wrapped
It includes: forming cap on the wordline surface；It is formed after the cap, removes the mask layer and mask layer bottom
Control gate and floating gate are respectively formed the first storage unit and the second storage unit positioned at wordline two sides.
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