CN102376555B - Method for improving reliability of SONOS (Silicon Oxide Nitride Oxide Semiconductor) by oxidizing ON film as tunneling dielectric medium - Google Patents
Method for improving reliability of SONOS (Silicon Oxide Nitride Oxide Semiconductor) by oxidizing ON film as tunneling dielectric medium Download PDFInfo
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Abstract
The invention discloses a method for improving the reliability of an SONOS (Silicon Oxide Nitride Oxide Semiconductor) by oxidizing an ON film as a tunneling dielectric medium, which comprises the following steps of: (1) growing a bottom ultra-thin oxide layer in the ON film on a silicon substrate; (2) growing a silicon-rich nitride film in the ON film on the ultra-thin oxide layer; (3) carrying out wet-oxygen oxidation on the silicon-rich nitride film in the ON film, and carrying out oxygen doping on the silicon-rich nitride film by oxidation to form a nitrogen and silicon oxide mixture; (4)forming a silicon nitride trap layer in the middle of an SONOS device into a film as a medium for storing charges; and (5) growing a high-temperature CVD (Chemical Vapor Deposition) oxide layer on the silicon nitride trap layer. The method does not reduce the erasing speed and simultaneously prolongs the life time of data retention as well as simplifies the difficulty of process control.
Description
Technical field
The invention belongs to semiconductor integrated circuit and make the field, be specifically related to a kind of method of manufacturing technology of SONOS flush memory device, relate in particular to the oxidation of a kind of ON film promotes the SONOS reliability as the tunnelling dielectric method.
Background technology
SONOS flush memory device (with the flush memory device of silicon nitride as charge storage media) becomes one of at present main flash type because possess good scaled down characteristic and radiation-resisting performance.The SONOS flush memory device also is faced with many problems on using.Wherein the problem that reliability is relevant mainly contains two: the one, Endurance (durable) characteristic, weigh the SONOS device exactly after program/erase repeatedly, the degeneration of device property aspect.The 2nd, Data Retention (data maintenance) characteristic is exactly the data hold capacity of SONOS device.The tunnel oxide of common SONOS flush memory device is generally thermal oxide layer, in order to reach higher erasable speed, so general thickness thinner (the 20 Izod right side), because oxide layer is thinner, cause electronics to be easier to escape, Data Retention ability (being the Data Retention life-span) is affected, has brought some problems therefore for the reliability of SONOS flush memory device.
Summary of the invention
The technical problem to be solved in the present invention provides the oxidation of a kind of ON film promotes the SONOS reliability as the tunnelling dielectric method.Guaranteeing that this method can increase the Data Retention life-span on the basis that does not reduce erasable speed, and has simplified the difficulty of technology controlling and process under the constant situation of electric field strength.
For solving the problems of the technologies described above, the invention provides the oxidation of a kind of ON film as the method for tunnelling dielectric lifting SONOS reliability, comprise the steps:
The first step, the bottom super thin oxide layer in silicon substrate growth ON film;
Second step, the Silicon-rich nitride film in this super thin oxide layer growth ON film;
The 3rd step, the Silicon-rich nitride film in the ON film is carried out wet-oxygen oxidation, utilize oxidation that the Silicon-rich nitride film is carried out oxygen and mix, form the silicon oxynitride mixture;
In the 4th step, the film forming of silicon nitride trap layer in the middle of the SONOS device is as the medium of stored charge;
The 5th step is in silicon nitride trap layer growth high temperature CVD oxide layer.
The first step adopts the low pressure thermal oxidation technology, and its process conditions are: growth pressure is 500mtorr～3000mtorr, and growth temperature is 600 ℃～1100 ℃; The thickness of described super thin oxide layer is 10 dusts～30 dusts.
Second step was adopted the high-temperature low-pressure chemical vapor deposition method, its process conditions are: growth pressure is 50mtorr～700mtorr, growth temperature is 500 ℃～900 ℃, and reacting gas is: silane or dichloro-dihydro silicon mix with ammonia, and two gas mixture ratio examples are 10: 1～1: 10; The thickness of described Silicon-rich nitride film is 20 dusts～80 dusts.
The 3rd step was adopted low pressure thermal oxidation technology or normal pressure nitrogen dilution thermal oxidation technology; The thickness of described silicon oxynitride mixture is 1/3～1/2 of Silicon-rich nitride film thickness.
The 3rd step adopted the process conditions of low pressure thermal oxidation technology to be: growth pressure is 500mtorr～4000mtorr, and growth temperature is 600 ℃～1100 ℃.
The 3rd step adopted the process conditions of normal pressure nitrogen dilution thermal oxidation technology to be: growth pressure is 760torr, and growth temperature is 600 ℃～1200 ℃, and the mixed proportion of nitrogen and oxygen is 1: 1～3: 1.
The 4th step was adopted the high-temperature low-pressure chemical vapor deposition method, its process conditions are: growth pressure is 100mtorr～5000mtorr, growth temperature is 500 ℃～800 ℃, and reacting gas is: silane or dichloro-dihydro silicon mix with ammonia, and two gas mixture ratio examples are 10: 1～1: 10; The thickness of described silicon nitride trap layer is 30 dusts～200 dusts.
The 5th step was adopted the high-temperature low-pressure chemical vapor deposition method, its process conditions are: growth pressure is 50mtorr～2000mtorr, growth temperature is 300 ℃～1000 ℃, reacting gas is: silane or dichloro-dihydro silicon mix with nitrous oxide gas, and two gas mixture ratio examples are 10: 1～1: 10; Described high temperature CVD thickness of oxide layer is 20 dusts～200 dusts.
Compare with prior art, the present invention has following beneficial effect: the present invention is a kind of method that the oxidation of ON film is promoted the SONOS reliability as the tunnelling dielectric film of utilizing.The SONOS device is because in order to guarantee certain erasable speed, and its tunnel oxide is all thinner (the 20 Izod right side) generally.Because oxide layer is thinner, cause electronics to be easier to escape, brought some problems therefore for the reliability of SONOS flush memory device, be mainly reflected on the Data Retention life-span.The present invention mainly utilizes individual layer thermal oxide layer that the oxidation of ON film replaces traditional SONOS device as the tunnelling dielectric, improves the Data Retention life-span of SONOS device.Since adopted the oxidation of ON film to make tunnel dielectric layer, thicker (as Fig. 2) that the more original tunnel oxide of its physical thickness comes, and therefore the method for ON film oxidation will obtain the better life-span when carrying out Data Retention test.ON film method for oxidation has also utilized the wherein silicon rich nitride layer energy gap lower with respect to oxide layer simultaneously.When the SONOS device carries out the erasable process of data (FN Tunneling (FN tunnelling) takes place), can band can deflect (as Fig. 3) of device, cause the electrical thickness of the real tunnelling of electronics still less, so still can under the constant situation of electric field strength, guarantee erasable speed faster.In addition, wherein replace traditional HTO (high temperature CVD oxide layer) owing to utilized the method for the thinner silicon oxynitride of ON film oxidation filming to make the upper strata tunnel barriers, therefore nitride film thickness can thicken relatively, has avoided grow up on the technology difficulty of ultra-thin nitride film and the homogeneity problem that the HTO film forming is brought.Technology of the present invention is fairly simple, is easy to integratedly, can be used for produce in batches.
Description of drawings
Fig. 1 is the schematic flow sheet of the inventive method; Figure 1A is the sectional view of SONOS flush memory device after the first step is finished among the present invention; Figure 1B be among the present invention second step finish after the sectional view of SONOS flush memory device; Fig. 1 C be among the present invention the 3rd step finish after the sectional view of SONOS flush memory device; Fig. 1 D be among the present invention the 4th step finish after the sectional view of SONOS flush memory device; Fig. 1 E be among the present invention the 5th step finish after the sectional view of SONOS flush memory device;
Fig. 2 is that traditional thermal oxide layer and ON film of the present invention oxidation can be with when test Data Retention compared schematic diagram;
Fig. 3 is that traditional thermal oxide layer and ON film of the present invention oxidation can be with when writing data compared schematic diagram.
Wherein, 1 is silicon substrate, and 2 is ultra-thin oxide-film, and 3 is the Silicon-rich nitride film, and 4 is the silicon oxynitride mixture, and 5 is silicon nitride trap layer, and 6 is high temperature CVD oxide layer.
Embodiment
The present invention is further detailed explanation below in conjunction with drawings and Examples.
A kind of method that the oxidation of ON film is promoted the SONOS reliability as the tunnelling dielectric film of utilizing of the present invention, its core is: utilize the method for ON film oxidation to replace the thermal oxide layer of traditional SONOS device as tunnel dielectric layer, by utilizing the silicon rich nitride layer energy gap lower with respect to oxide layer, increased the Data Retention life-span on the basis that does not reduce erasable speed, and utilized the wherein method of Silicon-rich nitride film oxidation, simplified the difficulty of technology controlling and process.
The main technological process of the inventive method comprises the steps (as shown in Figure 1):
The first step, shown in Figure 1A, bottom super thin oxide layer film forming in the ON film, i.e. grow ultra-thin oxide-film 2 on silicon substrate 1, the thickness range of ultra-thin oxide-film 2 is 10 dusts～30 dusts.This step process need adopt the low pressure thermal oxidation technology, and its process conditions are: growth pressure is 500mtorr～3000mtorr, and growth temperature is 600 ℃～1100 ℃.
Second step, as shown in Figure 1B, Silicon-rich nitride film film forming in the ON film, namely at ultra-thin oxide-film 2 growth Silicon-rich nitride films 3, the thickness range of Silicon-rich nitride film 3 is 20 dusts～80 dusts.This step process adopts the high-temperature low-pressure chemical vapor deposition method, its process conditions are: growth pressure is 50mtorr～700mtorr, growth temperature is 500 ℃～900 ℃, and reacting gas is: silane or dichloro-dihydro silicon mix with ammonia, and two gas mixture ratio examples are: 10: 1～1: 10.
The 3rd step, shown in Fig. 1 C, Silicon-rich nitride film in the ON film is carried out thermal oxidation, utilizing oxidation that Silicon-rich nitride film 3 is carried out oxygen mixes, form silicon oxynitride mixture 4, the thickness of silicon oxynitride mixture 4 is generally 1/3～1/2 of Silicon-rich nitride film 3 thickness, and this step process adopts low pressure thermal oxidation technology or normal pressure nitrogen dilution thermal oxidation technology.Process conditions are when adopting the low pressure thermal oxidation technology: growth pressure is 500mtorr～4000mtorr, and growth temperature is 600 ℃～1100 ℃.Adopt the process conditions of normal pressure nitrogen dilution thermal oxidation technology to be: growth pressure is 760torr (normal pressure), and growth temperature is 600 ℃～1200 ℃, and the mixed proportion of nitrogen and oxygen is 1: 1～3: 1.
The 4th step, shown in Fig. 1 D, the film forming of silicon nitride trap layer in the middle of the SONOS device, namely on silicon oxynitride mixture 4 grown silicon nitride trap layer 5 as the medium of stored charge, the thickness range of silicon nitride trap layer 5 is 30 dusts～200 dusts, this step process adopts the high-temperature low-pressure chemical vapor deposition method, its process conditions are: growth pressure is 100mtorr～5000mtorr, growth temperature is 500 ℃～800 ℃, reacting gas is: silane or dichloro-dihydro silicon mix with ammonia, and two gas mixture ratio examples are 10: 1～1: 10.
In the 5th step, shown in Fig. 1 E, electric charge stops the preparation of high temperature CVD oxide layer, and namely in silicon nitride trap layer 5 growth high temperature CVD oxide layers 6, the thickness range of high temperature CVD oxide layer 6 is 20 dusts～200 dusts; This step process adopts the high-temperature low-pressure chemical vapor deposition method, its process conditions are: growth pressure is 50mtorr～2000mtorr, growth temperature is 300 ℃～1000 ℃, reacting gas is: silane or dichloro-dihydro silicon mix with nitrous oxide gas, and two gas mixture ratio examples are 10: 1～1: 10.
Above-mentioned technological parameter needs to be optimized adjustment according to corresponding control and production capacity.
The present invention is a kind of method that the oxidation of ON film is promoted the SONOS reliability as the tunnelling dielectric film of utilizing.The SONOS device is because in order to guarantee certain erasable speed, and its tunnel oxide is all thinner (the 20 Izod right side) generally.Because oxide layer is thinner, cause electronics to be easier to escape, brought some problems therefore for the reliability of SONOS flush memory device, be mainly reflected on the Data Retention life-span.The present invention mainly utilizes the oxidation of ON film to replace conventional individual layer thermal oxide layer as tunnel dielectric layer, improves the Data Retention life-span of SONOS device.Therefore ON film method for oxidation mainly is to have utilized the wherein silicon rich nitride layer energy gap lower with respect to oxide layer, when the SONOS device carries out the erasable process of data (FN Tunneling takes place), still can guarantee erasable speed faster.Therefore simultaneously, owing to after the ON film forming silicon rich oxide layer is carried out oxidation, thickened with respect to the total physical thickness of tunnel oxide, so that the Data Retention life-span of SONOS device be improved.Wherein owing to utilized the method for ON film oxidation, so nitride film thickness can thicken relatively, avoided the difficulty of the ultra-thin nitride film of growing up on the technology.
Claims (5)
1. ON film oxidation is characterized in that as the method for tunnelling dielectric lifting SONOS reliability, comprises the steps:
The first step, the bottom super thin oxide layer in silicon substrate growth ON film; The first step adopts the low pressure thermal oxidation technology, and its process conditions are: growth pressure is 500mtorr～3000mtorr, and growth temperature is 600 ℃～1100 ℃; The thickness of described super thin oxide layer is 10 dusts～30 dusts;
Second step, the Silicon-rich nitride film in this super thin oxide layer growth ON film; Second step was adopted the high-temperature low-pressure chemical vapor deposition method, its process conditions are: growth pressure is 50mtorr～700mtorr, growth temperature is 500 ℃～900 ℃, and reacting gas is: silane or dichloro-dihydro silicon mix with ammonia, and two gas mixture ratio examples are 10: 1～1: 10; The thickness of described Silicon-rich nitride film is 20 dusts～80 dusts;
The 3rd step, the Silicon-rich nitride film in the ON film is carried out wet-oxygen oxidation, utilize oxidation that the Silicon-rich nitride film is carried out oxygen and mix, form the silicon oxynitride mixture; The 3rd step was adopted low pressure thermal oxidation technology or normal pressure nitrogen dilution thermal oxidation technology; The thickness of described silicon oxynitride mixture is 1/3～1/2 of Silicon-rich nitride film thickness;
In the 4th step, the film forming of silicon nitride trap layer in the middle of the SONOS device is as the medium of stored charge;
The 5th step is in silicon nitride trap layer growth high temperature CVD oxide layer.
2. ON film as claimed in claim 1 oxidation promotes the method for SONOS reliability as the tunnelling dielectric, it is characterized in that, the 3rd step adopted the process conditions of low pressure thermal oxidation technology to be: growth pressure is 500mtorr～4000mtorr, and growth temperature is 600 ℃～1100 ℃.
3. ON film as claimed in claim 1 oxidation promotes the method for SONOS reliability as the tunnelling dielectric, it is characterized in that, the 3rd step adopted the process conditions of normal pressure nitrogen dilution thermal oxidation technology to be: growth pressure is 760torr, growth temperature is 600 ℃～1200 ℃, and the mixed proportion of nitrogen and oxygen is 1: 1～3: 1.
4. ON film as claimed in claim 1 oxidation promotes the method for SONOS reliability as the tunnelling dielectric, it is characterized in that, the 4th step was adopted the high-temperature low-pressure chemical vapor deposition method, its process conditions are: growth pressure is 100mtorr～5000mtorr, growth temperature is 500 ℃～800 ℃, reacting gas is: silane or dichloro-dihydro silicon mix with ammonia, and two gas mixture ratio examples are 10: 1～1: 10; The thickness of described silicon nitride trap layer is 30 dusts～200 dusts.
5. ON film as claimed in claim 1 oxidation promotes the method for SONOS reliability as the tunnelling dielectric, it is characterized in that, the 5th step was adopted the high-temperature low-pressure chemical vapor deposition method, its process conditions are: growth pressure is 50mtorr～2000mtorr, growth temperature is 300 ℃～1000 ℃, reacting gas is: silane or dichloro-dihydro silicon mix with nitrous oxide gas, and two gas mixture ratio examples are 10: 1～1: 10; Described high temperature CVD thickness of oxide layer is 20 dusts～200 dusts.
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| CN101154688A (en) * | 2006-09-29 | 2008-04-02 | 株式会社东芝 | Nonvolatile semiconductor memory |
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| CN1330393A (en) * | 2000-06-29 | 2002-01-09 | 株式会社东芝 | Semiconductor device and manufacturing method for semiconductor device |
| CN101154688A (en) * | 2006-09-29 | 2008-04-02 | 株式会社东芝 | Nonvolatile semiconductor memory |
| CN101079434A (en) * | 2007-06-12 | 2007-11-28 | 北京大学 | 3D dual fin channel dual-bar multi-function field effect transistor and its making method |
| CN101364615A (en) * | 2007-08-08 | 2009-02-11 | 旺宏电子股份有限公司 | Nonvolatile memory and forming method for the same |
| CN101471384A (en) * | 2007-12-28 | 2009-07-01 | 东部高科股份有限公司 | Nonvolatile memory device and method for manufacturing the same |
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