CN109887915A - Flush memory device and its manufacturing method - Google Patents
Flush memory device and its manufacturing method Download PDFInfo
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- CN109887915A CN109887915A CN201910172992.9A CN201910172992A CN109887915A CN 109887915 A CN109887915 A CN 109887915A CN 201910172992 A CN201910172992 A CN 201910172992A CN 109887915 A CN109887915 A CN 109887915A
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Abstract
The present invention provides a kind of flush memory device and its manufacturing method, the manufacturing method of the flush memory device includes: to provide a substrate, forms multiple fleet plough groove isolation structures over the substrate；It is etched back to the side wall of the fleet plough groove isolation structure, to form first groove on the substrate between the adjacent fleet plough groove isolation structure, the width at the top of the first groove is greater than the width of its bottom；Floating gate is formed in the first groove；It is etched back to the top of the fleet plough groove isolation structure, to form the second groove for the side wall for exposing the floating gate, the width of the second groove bottom is greater than the width at the top of it；And filled layer is formed in the second groove, cavity is formed between the side wall of the filled layer and the side wall of the floating gate bottom.Technical solution of the present invention also to can reduce the crosstalk between floating gate, so that the reliability of flush memory device is improved while the width of floating gate increases.
Description
Technical field
The present invention relates to IC manufacturing field, in particular to a kind of flush memory device and its manufacturing method.
Background technique
Flash memory (Flash) is a kind of read-only memory of the repeatable programming of electrical property, has been storage since it quickly grows
The pillar in device market.Compared with the read-only memory of the repeatable programming of traditional electrical property, flash memory is carrying out electrically erasable and is repeating to compile
It in the engineering of journey, does not need that additional external high voltage is added in systems, and flash memory is big with density of memory cells, collection
The high, feature at low cost at degree.Currently, flash memory is widely used at mobile communication, data due to its excellent performance
In the new high-tech industries such as reason, intelligent terminal, embedded system, as PC and its external equipment, automotive electronics, network are handed over
It changes planes, internet device and instrument and meter, while further including novel digital camera, personal digital assistant, smart phone peace
Plate computer etc..As these electronic products are received and used by more and more people, to the function of flash memory, capacity, power consumption, volume etc.
It made higher requirement.Especially nowadays the high performance flash memory of small size has become the mainstream in market, and this requires it to make
The line width for making technique is smaller and smaller, from 0.13 μm, 90nm, 65nm to 50nm, 40nm, 20nm it is even more small, and work as line width contracting
Small, more and more small-size effects also will become more apparent.
For the flash memory with floating gate (FG) structure, particularly as being scene effect transistor (FET, Field Effect
Transistor floating gate is added in), stores the information of a bit (Bit) by the state of electronics in floating gate, i.e., " 0 " or
"1".This floating gate is normally between control gate (CG) and tunnel oxide (Tunnel oxide), wherein control gate and floating gate
Between separated by dielectric layer between grid.In order to guarantee that floating gate can store enough electronics and ensure the erasable speed of flush memory device
Degree, it is desirable that the size of floating gate cannot be done too small.
The manufacturing method of flush memory device with FGS floating gate structure generally comprises following steps:
Firstly, sequentially forming sacrificial oxide layer 111 on substrate 10 and sacrificing nitration case 112, refering to fig. 1 a；
Then, it is sequentially etched and sacrifices nitration case 112, sacrificial oxide layer 111 and substrate 10, to form first groove 121, and
Fleet plough groove isolation structure 122 (STI) is formed after being filled to first groove 121, refering to fig. 1 b and 1c；
Then, nitration case 112 and sacrificial oxide layer 111 are sacrificed in removal, and are carried out to the side wall of fleet plough groove isolation structure 122
The second groove 131 being located on substrate 10 is formed after being etched back to, and then, ion implanting can be carried out into substrate 10 and forms well region
132, d refering to fig. 1；
Then, bottom-up in second groove 131 to sequentially form tunnel oxide 141 and floating gate 142, e refering to fig. 1；
Then, it is etched back to fleet plough groove isolation structure 122, so that the top surface of fleet plough groove isolation structure 122 is lower than floating gate 142
Top surface and be higher than the top surface of tunnel oxide 141, f refering to fig. 1；
Then, dielectric layer 151 and control gate 152 between the top of floating gate 142 sequentially forms grid, refering to fig. 1 g.
It can be seen that from the manufacturing step of the above flush memory device with FGS floating gate structure, it, can in order to increase the size of floating gate
To consider to increase the thickness or width of floating gate, but if the thickness of floating gate is done too big, subsequent filled media layer can be made
There is abnormal (such as having empty generation) in technique, and then leads to the electric leakage for occurring big between Bit and Bit, therefore, can only select
Increase the transverse width of floating gate.But if the transverse width of floating gate increases, lateral distance will reduce between adjacent floating gate,
Increase so as to cause the effect of intercoupling (crosstalk between i.e. adjacent floating gate) between adjacent Bit, and then influences flush memory device
Programming, erasable state so that the reliability of flush memory device reduces.
Therefore, how the manufacturing process of the existing flush memory device with FGS floating gate structure is improved, so that floating
While the width of grid increases, the crosstalk between floating gate can be also reduced, and then the reliability for improving flush memory device is current
The problem of urgent need to resolve.
Summary of the invention
The purpose of the present invention is to provide a kind of flush memory device and its manufacturing methods so that floating gate width increase it is same
When, it also can reduce the crosstalk between floating gate, so that the reliability of flush memory device is improved.
To achieve the above object, the present invention provides a kind of manufacturing methods of flush memory device, comprising:
One substrate is provided, forms multiple fleet plough groove isolation structures, the top of the fleet plough groove isolation structure over the substrate
Surface is higher than the top surface of the substrate；
It is etched back to the side wall of the fleet plough groove isolation structure, described between the adjacent fleet plough groove isolation structure
First groove is formed on substrate, the width at the top of the first groove is greater than the width of its bottom；
Floating gate is formed in the first groove, the width at the top of the floating gate is greater than the width of its bottom；
It is etched back to the top of the fleet plough groove isolation structure, to form the second groove for the side wall for exposing the floating gate,
The width of the second groove bottom is greater than the width at the top of it；And
Filled layer is formed in the second groove, shape between the side wall of the filled layer and the side wall of the floating gate bottom
At cavity.
Optionally, over the substrate formed fleet plough groove isolation structure the step of include:
Sacrificial layer is formed on the substrate；
It is sequentially etched the sacrificial layer and the substrate, to form third groove；
Isolating oxide layer is filled in the third groove, the isolating oxide layer fills up the third groove, and will
In the sacrificial layer is buried in；
The isolating oxide layer is ground using chemical mechanical milling tech, and is stopped on the top surface of the sacrificial layer；
And
Remove the sacrificial layer.
Optionally, the step of forming the sacrificial layer includes: successively to form sacrificial oxide layer and sacrifice over the substrate
Nitration case.
Optionally, it is repeatedly etched back to the side wall of the fleet plough groove isolation structure, so that the side wall packet of the first groove
Containing at least one layer of step.
Optionally, before forming the floating gate in the first groove, tunnel oxide is initially formed in first ditch
The bottom of slot.
Optionally, it is formed after the first groove, and is formed before the tunnel oxide, the substrate is carried out
Ion implanting, to form well region in the substrate.
Optionally, forming step of the filled layer in the second groove includes:
Filled layer is deposited in the second groove, the side wall of the filled layer and the close fleet plough groove isolation structure
Form cavity between the side wall of the bottom of the floating gate of top surface, and in the floating gate is buried in by the filled layer；
The filled layer is ground using chemical mechanical milling tech, and is stopped on the top surface of the floating gate；And
The filled layer of segment thickness is removed, so that the top surface of the filled layer is lower than the top surface of the floating gate
And it is higher than the cavity.
Optionally, the material of the filled layer includes silica, silicon nitride or oxide-nitride-oxide.
Optionally, after forming the filled layer in the second groove, dielectric layer and control between grid are sequentially formed
Grid are on the floating gate.
The present invention also provides a kind of flush memory devices, comprising:
One substrate with fleet plough groove isolation structure；
The floating gate on the substrate between the adjacent fleet plough groove isolation structure, the width at the top of the floating gate are big
Width in its bottom；And
The filled layer on the fleet plough groove isolation structure between the adjacent floating gate, the side of the filled layer
Cavity is formed between wall and the side wall of the floating gate bottom.
Optionally, the flush memory device further includes the tunnel oxide between the floating gate and the substrate.
It optionally, include a well region in the substrate.
Optionally, the side wall and the top surface close to the fleet plough groove isolation structure that the cavity is located at the filled layer
Between the side wall of the bottom of the floating gate, the top surface of the filled layer is lower than the top surface of the floating gate and is higher than the sky
Hole.
Optionally, the material of the filled layer includes silica, silicon nitride or oxide-nitride-oxide.
Optionally, the flush memory device further includes dielectric layer and control gate between the grid on the floating gate.
Compared with prior art, technical solution of the present invention has the advantages that
1, the manufacturing method of flush memory device of the invention first passes through the side wall for being etched back to fleet plough groove isolation structure to form top
The width in portion is greater than the first groove of the width of its bottom, and forms floating gate in first groove, then by being etched back to shallow trench
The top of isolation structure forms filled layer in second groove, and fill out to form the second groove for the side wall for exposing floating gate
It fills and forms cavity between the side wall of layer and the side wall of floating gate bottom, so that can also be dropped while the width of floating gate increases
Crosstalk between low floating gate, so that the reliability of flush memory device is improved.
2, flush memory device of the invention, due to the filled layer and floating gate on the fleet plough groove isolation structure between adjacent floating gate
It is formed with cavity between the side wall of bottom, so that also can reduce the crosstalk between floating gate while the width of floating gate increases,
So that the reliability of flush memory device is improved.
Detailed description of the invention
Fig. 1 a~1g is the device schematic diagram in the manufacturing method of existing flush memory device；
Fig. 2 is the flow chart of the manufacturing method of the flush memory device of one embodiment of the invention；
Fig. 3 a~3j is the device schematic diagram in the manufacturing method of flush memory device shown in Fig. 2.
Wherein, the reference numerals are as follows by attached drawing 1a~3j:
10- substrate；111- sacrificial oxide layer；112- sacrifices nitration case；121- first groove；122- shallow trench isolation knot
Structure；131- second groove；132- well region；141- tunnel oxide；142- floating gate；Dielectric layer between 151- grid；152- control gate；
20- substrate；21- sacrificial layer；211- sacrificial oxide layer；212- sacrifices nitration case；22- fleet plough groove isolation structure；221- third ditch
Slot；222- isolating oxide layer；231- first groove；2311- first part；2312- second part；232- well region；241- tunnelling
Oxide layer；242- floating gate；243- second groove；The cavity 244-；25- filled layer；Dielectric layer between 261- grid；262- control gate.
Specific embodiment
To keep the purpose of the present invention, advantages and features clearer, below in conjunction with attached drawing 1a~3j to proposed by the present invention
Flush memory device and its manufacturing method are described in further detail.It should be noted that attached drawing is all made of very simplified form and
Using non-accurate ratio, only for the purpose of facilitating and clarifying the purpose of the embodiments of the invention.
One embodiment of the invention provides a kind of manufacturing method of flush memory device, referring to Fig.2, Fig. 2 is one embodiment of the invention
Flush memory device manufacturing method flow chart, the manufacturing method of the flush memory device includes:
Step S1, a substrate is provided, forms multiple fleet plough groove isolation structures, the shallow trench isolation knot over the substrate
The top surface of structure is higher than the top surface of the substrate；
Step S2, be etched back to the side wall of the fleet plough groove isolation structure, with the adjacent fleet plough groove isolation structure it
Between the substrate on form first groove, the width at the top of the first groove be greater than its bottom width；
Step S3, floating gate is formed in the first groove, and the width at the top of the floating gate is greater than the width of its bottom；
Step S4, it is etched back to the top of the fleet plough groove isolation structure, to form the of the side wall for exposing the floating gate
Two grooves, the width of the second groove bottom are greater than the width at the top of it；
Step S5, filled layer is formed in the second groove, the side of the side wall of the filled layer and the floating gate bottom
Cavity is formed between wall.
Introduce the manufacturing method of flush memory device provided in this embodiment in more detail referring next to Fig. 3 a~3j, Fig. 3 a~
3j is the device schematic diagram in the manufacturing method of flush memory device shown in Fig. 2.
Firstly, according to step S1, providing a substrate 20 refering to Fig. 3 a~3d, forming multiple shallow ridges on the substrate 20
Recess isolating structure 22, the top surface of the fleet plough groove isolation structure 22 are higher than the top surface of the substrate 20.
Wherein, on the substrate 20 formed fleet plough groove isolation structure 22 the step of include: firstly, formed sacrificial layer 21 in
On the substrate 20, as shown in Figure 3a；Then, it is sequentially etched the sacrificial layer 21 and the substrate 20, to form third groove
221, as shown in Figure 3b；Then, for filling isolating oxide layer 222 in the third groove 221, the isolating oxide layer 222 will
The third groove 221 fills up, and in the sacrificial layer 21 is buried in；Then, institute is ground using chemical mechanical milling tech
Isolating oxide layer 222 is stated, and is stopped on the top surface of the sacrificial layer 21, as shown in Figure 3c；Then, the sacrificial layer is removed
21, so that the top surface of the fleet plough groove isolation structure 22 formed is higher than the top surface of the substrate 20, as shown in Figure 3d.
Wherein, the step of can be seen that from Fig. 3 a, forming sacrificial layer 21 may include: successively to be formed to sacrifice on the substrate 20
Oxide layer 211 and sacrifice nitration case 212.The material of the isolating oxide layer 222 and the sacrificial oxide layer 211 can be oxidation
Silicon, the material for sacrificing nitration case 212 can be silicon nitride.It forms the sacrificial layer 21 and fills the isolating oxide layer
222 method may include chemical vapor deposition, physical vapour deposition (PVD) etc., etch the sacrificial layer 21 and the substrate 20 and
The method for removing the sacrificial layer 21 can be dry etching or wet etching.
Then, it is etched back to the side wall of the fleet plough groove isolation structure 22, adjacent according to step S2 refering to Fig. 3 e
First groove 231, the width at 231 top of first groove are formed on the substrate 20 between the fleet plough groove isolation structure 22
Degree is greater than the width of its bottom.In the present embodiment, can by being repeatedly etched back to the side wall of the fleet plough groove isolation structure 22, with
So that the side wall of the first groove 231 includes at least one layer of step, so that the width at 231 top of the first groove is big
Width in its bottom.It can be seen that from Fig. 3 e, the side wall of the first groove 231 includes one layer of step, so that described first
Groove 231 is made of first part 2311 and second part 2312, the first part 2311 of the first groove 231 perpendicular to
The width in the section on 20 surface of substrate is greater than the width in the section perpendicular to 20 surface of substrate of second part 2312,
Can first be exposed to obtain the lesser mask layer of opening size using the relatively small mask plate of opening figure size, then with
The mask layer is the side wall that exposure mask is etched back to the fleet plough groove isolation structure 22, then relatively large sized using another opening figure
Mask plate be exposed to obtain the biggish mask layer of opening size, be then etched back to the shallow trench by exposure mask of the mask layer
The side wall of isolation structure 22, to obtain first part 2311 and the second part 2312 of the first groove 231.And when described the
When the side wall of one groove 231 includes two layers of step, it can be obtained by being etched back to the side wall of the fleet plough groove isolation structure 22 three times,
Detailed process repeats no more.In other embodiments, the side wall of the first groove 231 may not be it is step-like, described first
The width of groove 231 can be gradually increased (longitudinal section shape of the i.e. described first groove 231 is inverted trapezoidal) from bottom to top, i.e.,
The side wall of the first groove 231 is tilted to the direction of the fleet plough groove isolation structure 22, so that the first groove 231 is pushed up
The width in portion is greater than the width of its bottom.
Then, floating gate 242 is formed in the first groove 231, the floating gate 242 pushes up according to step S3 refering to Fig. 3 f
The width in portion is greater than the width of its bottom.In the present embodiment, in conjunction with the side wall packet of the first groove 231 proposed in step S2
It when containing one layer of step, can be seen that from Fig. 3 f, the T-shaped structure in longitudinal cross-section of the floating gate 242.In other embodiments, that is, walk
The width of the first groove 231 proposed in rapid S2 is gradually increased from bottom to top, then the longitudinal cross-section of the floating gate 242 is in
Trapezium structure.Before the floating gate 242 is formed in the first groove 231, tunnel oxide 241 is initially formed in described first
The bottom of groove 231.Also, it is formed after the first groove 231, and is formed before the tunnel oxide 241, it can be with
Ion implanting is carried out to the substrate 20, to form well region 232 in the substrate 20.The well region 232 may include p-type or
The ion of N-type.The method for forming the tunnel oxide 241 and the floating gate 242 may include chemical vapor deposition, physics gas
The material of mutually deposition etc., the tunnel oxide 241 can be silica, and the material of the floating gate 242 can be polysilicon.
Then, it is etched back to the top of the fleet plough groove isolation structure 22, to form exposure according to step S4 refering to Fig. 3 g
The second groove 243 of the side wall of the floating gate 242 out, the width of 243 bottom of second groove are greater than the width at the top of it.It returns
After the top for etching the fleet plough groove isolation structure 22, the bottom wall of the second groove 243 can be with the tunnel oxide
241 top surface flushes；Alternatively, the bottom wall of the second groove 243 is slightly below the top surface of the tunnel oxide 241, example
Such as flushed with the top surface of the substrate 20；Again alternatively, the bottom wall of the second groove 243 is slightly above the tunnel oxide
241 top surface, still, the height of the bottom wall of the second groove 243 need to not influence the filled layer 25 being subsequently formed
Cavity 244 is formed between the side wall of 242 bottom of side wall and the floating gate.The method for forming the second groove 243 may include
Wet etching, dry etching, alternatively, wet etching is combined with dry etching.
Finally, according to step S5, forming filled layer 25 in the second groove 243, the filling refering to Fig. 3 h~3j
Cavity 244 is formed between the side wall of 242 bottom of side wall and the floating gate of layer 25.The filled layer 25 is formed in second ditch
Step in slot 243 include: first deposition filled layer 25 in the second groove 243, the side wall of the filled layer 25 with it is close
Cavity 244 is formed between the side wall of the bottom of the floating gate 242 of the top surface of the fleet plough groove isolation structure 22, and described is filled out
It fills in the floating gate 242 is buried in by layer 25；Then, the filled layer 25 is ground using chemical mechanical milling tech, and stopped
On the top surface of the floating gate 242, as illustrated in figure 3h；Then, the filled layer 25 for removing segment thickness, so that described
The top surface of filled layer 25 is lower than the top surface of the floating gate 242 and is higher than described empty 244, as shown in figure 3i.The filling
The top surface of layer 25 makes between the floating gate 242 and the control gate 262 formed later lower than the top surface of the floating gate 242
Coupling efficiency is increased, and then promotes the programmable and erasure rate of flush memory device.The shape of empty 244 longitudinal cross-section can
Think single rectangular, multiple rectangular combinations or triangle etc., and the shape of empty 244 longitudinal cross-section is mainly by step S2
In the side wall for being etched back to the fleet plough groove isolation structure 22 number and technological parameter determine.For example, when described empty 244
When the shape of longitudinal cross-section is single rectangular, i.e. two are carried out to the side wall of the fleet plough groove isolation structure 22 in above-mentioned steps S2
Secondary is etched back to；When the shape of empty 244 longitudinal cross-section is multiple rectangular combinations, i.e. to described in above-mentioned steps S2
The side wall of fleet plough groove isolation structure 22 has carried out at least being etched back to three times.Certainly, the shape of empty 244 longitudinal cross-section
Also it will receive the influence to form technique of the filled layer 25 in the second groove 243.
In addition, depositing work by control during deposition forms the filled layer 25 in the second groove 243
The process parameters such as the deposition velocity of skill, so that the plasma defect on the filled layer 25 is reduced, so that shape
At the filled layer 25 surface it is more smooth and have uniform interface charge so that the uniformity of flush memory device and
Reliability is improved.Also, the mobility of the material of the filled layer 25 is poor, so that the side wall of the filled layer 25 and institute
It states and described empty 244 is more readily formed between the side wall of 242 bottom of floating gate；Simultaneously as the stream of the material of the filled layer 25
Dynamic property is poor, so that the filled layer 25 has better interfacial state, and then but also the uniformity and reliability of flush memory device obtain
To raising.The material of the filled layer 25 may include silica, silicon nitride or oxide-nitride-oxide (ONO) etc..
In addition, since there are described empty 244 between the side wall of 242 bottom of side wall and the floating gate of the filled layer 25, so that
The width of the floating gate 242 increases to while meet process requirements, and the lateral distance between the adjacent floating gate 242 also can
Increased, to reduce the crosstalk between the adjacent floating gate 242；Moreover, be air in described empty 244, and Jie of air
Electric constant is low, so that the crosstalk between the adjacent floating gate 242 further decreases, so that the reliability of flush memory device obtains
To raising.
In addition, can be seen that from Fig. 3 j, after forming the filled layer 25 in the second groove 243, successively shape
At dielectric layer 261 between grid and control gate 262 on the floating gate 242.Dielectric layer 261 and control between the grid can be first sequentially depositing
The material of grid 262 processed is on the floating gate 242 and the filled layer 25, then etches the material removed on the filled layer 25, with
Dielectric layer 261 and control gate 262 between the grid are formed on the floating gate 242.The material of dielectric layer 261 can wrap between the grid
Silica, silicon nitride or oxide-nitride-oxide (ONO) etc. are included, the material of the control gate 262 can be polysilicon.
In addition, the manufacturing method of the flush memory device of above-mentioned steps S1 to step S5 is especially suitable for manufacturing 55nm node or less
Flush memory device, and manufacture craft is simple, is easier to realize.
In conclusion the manufacturing method of flush memory device provided by the invention, comprising: provide a substrate, over the substrate
Multiple fleet plough groove isolation structures are formed, the top surface of the fleet plough groove isolation structure is higher than the top surface of the substrate；It is etched back to
The side wall of the fleet plough groove isolation structure, to form first on the substrate between the adjacent fleet plough groove isolation structure
Groove, the width at the top of the first groove are greater than the width of its bottom；Floating gate is formed in the first groove, the floating gate
The width at top is greater than the width of its bottom；It is etched back to the top of the fleet plough groove isolation structure, exposes described float to be formed
The second groove of the side wall of grid, the width of the second groove bottom are greater than the width at the top of it；And filled layer is formed in institute
It states in second groove, forms cavity between the side wall of the filled layer and the side wall of the floating gate bottom.Skill through the invention
Art scheme, so that also can reduce the crosstalk between floating gate while the width of floating gate increases, so that flush memory device
Reliability is improved.
One embodiment of the invention provides a kind of flush memory device, can be seen that from Fig. 3 j, and the semiconductor devices includes substrate
20, floating gate 242 and filled layer 25, the substrate 20 have fleet plough groove isolation structure 22；The floating gate 242 is located at adjacent described
On the substrate 20 between fleet plough groove isolation structure 22, the width at 242 top of floating gate is greater than the width of its bottom；And
The filled layer 25 is on the fleet plough groove isolation structure 22 between the adjacent floating gate 242, the side of the filled layer 25
Cavity 244 is formed between the side wall of 242 bottom of wall and the floating gate.
Flush memory device provided in this embodiment is described in detail referring next to Fig. 3 j:
The substrate 20 has fleet plough groove isolation structure 22, the top surface and the substrate of the fleet plough groove isolation structure 22
20 top surface flushes；Alternatively, top surface of the top surface of the fleet plough groove isolation structure 22 higher than the substrate 20, but institute
The height for stating the top surface of fleet plough groove isolation structure 22 does not influence the side wall of the filled layer 25 and the side of 242 bottom of floating gate
Cavity 244 is formed between wall, for example, the top surface of the fleet plough groove isolation structure 22 can be with the tunnel oxide that is formed later
241 top surface flushes.May include a well region 232 in the substrate 20, may include in the well region 232 p-type or N-type from
Son.
The floating gate 242 is on the substrate 20 between the adjacent fleet plough groove isolation structure 22, the floating gate 242
The width at top is greater than the width of its bottom.It may also include tunnel oxide 241 between the floating gate 242 and the substrate 20.
It the longitudinal cross-section of the floating gate 242 can be with T-shaped structure, so that forming cavity in the lower section of the transverse ends of T-shaped structure
244；Alternatively, the longitudinal cross-section of the floating gate 242 is in inverted trapezoidal structure, so that side wall and institute in 242 bottom of floating gate
It states and forms cavity 244 between the side wall of filled layer 25.The shape of empty 244 longitudinal cross-section can be single rectangular, more
A rectangular combination or triangle etc..The material of the tunnel oxide 241 can be silica, and the material of the floating gate 242 can
Think polysilicon.
The filled layer 25 is on the fleet plough groove isolation structure 22 between the adjacent floating gate 242, the cavity
244 are located at the bottom of the floating gate 242 of the top surface of the side wall of the filled layer 25 and the close fleet plough groove isolation structure 22
Between the side wall in portion.The top surface of the filled layer 25 is lower than the top surface of the floating gate 242 and is higher than described empty 244.Institute
The top surface for stating filled layer 25 makes the control gate 262 floating gate 242 and formed later lower than the top surface of the floating gate 242
Between coupling efficiency increased, and then promote the programmable and erasure rate of flush memory device.The material of the filled layer 25 can be with
Including silica, silicon nitride or oxide-nitride-oxide (ONO) etc..In addition, due on the filled layer 25 it is equal from
Daughter defect is reduced, so that the surface of the filled layer 25 formed is more smooth and has uniform interface charge, into
And the uniformity of flush memory device and reliability are improved.Also, the mobility of the material of the filled layer 25 is poor, makes
It obtains and is more readily formed described empty 244 between the side wall of 242 bottom of side wall and the floating gate of the filled layer 25；Meanwhile by
In the poor fluidity of the material of the filled layer 25, so that the filled layer 25 has better interfacial state, and then but also dodge
The uniformity and reliability of memory device are improved.In addition, side wall and 242 bottom of floating gate due to the filled layer 25
There are described empty 244 between side wall so that the floating gate 242 width increase to meet process requirements while, it is adjacent
The floating gate 242 between lateral distance can also be increased, to reduce the crosstalk between the adjacent floating gate 242；Moreover,
It is air in described empty 244, and the dielectric constant of air is low, so that the crosstalk between the adjacent floating gate 242 is further
It reduces, so that the reliability of flush memory device is improved.
In addition, further including dielectric layer 261 and control gate 262 between grid on the floating gate 242.Dielectric layer 261 between the grid
Material may include silica, silicon nitride or oxide-nitride-oxide (ONO) etc., and the material of the control gate 262 can
Think polysilicon.
In conclusion flush memory device provided by the invention, comprising: a substrate with fleet plough groove isolation structure；Positioned at phase
The floating gate on the substrate between the adjacent fleet plough groove isolation structure, the width at the top of the floating gate are greater than the width of its bottom
Degree；And the filled layer on the fleet plough groove isolation structure between the adjacent floating gate, the side of the filled layer
Cavity is formed between wall and the side wall of the floating gate bottom.Flush memory device provided by the invention make floating gate width increase
Meanwhile also can reduce the crosstalk between floating gate, so that the reliability of flush memory device is improved.
Foregoing description is only the description to present pre-ferred embodiments, not to any restriction of the scope of the invention, this hair
Any change, the modification that the those of ordinary skill in bright field does according to the disclosure above content, belong to the protection of claims
Range.
Claims (15)
1. a kind of manufacturing method of flush memory device characterized by comprising
One substrate is provided, forms multiple fleet plough groove isolation structures, the top surface of the fleet plough groove isolation structure over the substrate
Higher than the top surface of the substrate；
It is etched back to the side wall of the fleet plough groove isolation structure, with the substrate between the adjacent fleet plough groove isolation structure
Upper formation first groove, the width at the top of the first groove are greater than the width of its bottom；
Floating gate is formed in the first groove, the width at the top of the floating gate is greater than the width of its bottom；
It is etched back to the top of the fleet plough groove isolation structure, it is described to form the second groove for the side wall for exposing the floating gate
The width of second groove bottom is greater than the width at the top of it；And
Filled layer is formed in the second groove, is formed between the side wall of the filled layer and the side wall of the floating gate bottom empty
Hole.
2. the manufacturing method of flush memory device as described in claim 1, which is characterized in that over the substrate formed shallow trench every
Include: from the step of structure
Sacrificial layer is formed on the substrate；
It is sequentially etched the sacrificial layer and the substrate, to form third groove；
Isolating oxide layer is filled in the third groove, the isolating oxide layer fills up the third groove, and will be described
In sacrificial layer is buried in；
The isolating oxide layer is ground using chemical mechanical milling tech, and is stopped on the top surface of the sacrificial layer；And
Remove the sacrificial layer.
3. the manufacturing method of flush memory device as claimed in claim 2, which is characterized in that the step of forming sacrificial layer packet
It includes: successively forming sacrificial oxide layer over the substrate and sacrifice nitration case.
4. the manufacturing method of flush memory device as described in claim 1, which is characterized in that be repeatedly etched back to the shallow trench isolation
The side wall of structure, so that the side wall of the first groove includes at least one layer of step.
5. the manufacturing method of flush memory device according to any one of claims 1 to 4, which is characterized in that form the floating gate
Before in the first groove, tunnel oxide is initially formed in the bottom of the first groove.
6. the manufacturing method of flush memory device as claimed in claim 5, which is characterized in that it is formed after the first groove, with
And formed before the tunnel oxide, ion implanting is carried out to the substrate, to form well region in the substrate.
7. the manufacturing method of flush memory device according to any one of claims 1 to 4, which is characterized in that form the filling
Step of the layer in the second groove include:
Filled layer is deposited in the second groove, the side wall of the filled layer and the top table close to the fleet plough groove isolation structure
Form cavity between the side wall of the bottom of the floating gate in face, and in the floating gate is buried in by the filled layer；
The filled layer is ground using chemical mechanical milling tech, and is stopped on the top surface of the floating gate；And
The filled layer of segment thickness is removed, so that the top surface of the filled layer is lower than the top surface and height of the floating gate
In the cavity.
8. the manufacturing method of flush memory device according to any one of claims 1 to 4, which is characterized in that the filled layer
Material includes silica, silicon nitride or oxide-nitride-oxide.
9. the manufacturing method of flush memory device according to any one of claims 1 to 4, which is characterized in that fill out described in the formation
After filling layer in the second groove, dielectric layer and control gate are sequentially formed between grid on the floating gate.
10. a kind of flush memory device characterized by comprising
One substrate with fleet plough groove isolation structure；
The floating gate on the substrate between the adjacent fleet plough groove isolation structure, the width at the top of the floating gate are greater than it
The width of bottom；And
The filled layer on the fleet plough groove isolation structure between the adjacent floating gate, the side wall of the filled layer with
Cavity is formed between the side wall of the floating gate bottom.
11. flush memory device as claimed in claim 10, which is characterized in that further include between the floating gate and the substrate
Tunnel oxide.
12. flush memory device as claimed in claim 10, which is characterized in that include a well region in the substrate.
13. the flush memory device as described in any one of claim 10 to 12, which is characterized in that the cavity is located at the filling
Between the side wall of the bottom of the floating gate of the top surface of the side wall of layer and the close fleet plough groove isolation structure, the filled layer
Top surface lower than the floating gate top surface and be higher than the cavity.
14. the flush memory device as described in any one of claim 10 to 12, which is characterized in that the material of the filled layer includes
Silica, silicon nitride or oxide-nitride-oxide.
15. the flush memory device as described in any one of claim 10 to 12, which is characterized in that further include being located on the floating gate
Grid between dielectric layer and control gate.
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