CN101928934B - Method for improving uniformity of high-temperature oxide of wafer - Google Patents
Method for improving uniformity of high-temperature oxide of wafer Download PDFInfo
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- CN101928934B CN101928934B CN2009100533768A CN200910053376A CN101928934B CN 101928934 B CN101928934 B CN 101928934B CN 2009100533768 A CN2009100533768 A CN 2009100533768A CN 200910053376 A CN200910053376 A CN 200910053376A CN 101928934 B CN101928934 B CN 101928934B
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- temperature oxide
- oxide layer
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Abstract
The invention discloses a method for improving uniformity of a high-temperature oxide of a wafer, comprising the following steps: continuously introducing gas forming the high-temperature oxide into a boat without the wafer until the high-temperature oxide the thickness of which is not less than 20,000angstrom is formed on the inner surface of the boat; and placing a plurality of wafers in the boat to deposit the high-temperature oxide. Therefore, the method improves the uniformity of the high-temperature oxide deposited by the wafer.
Description
Technical field
The present invention relates to field of manufacturing semiconductor devices, particularly a kind of method that improves the uniformity of high-temperature oxide of wafer.
Background technology
At present, constitute electrical condenser as dielectric substance, be used for store charge with oxide layer-nitride layer-oxide layer (ONO) three-decker.The ONO structure is called charge storage layer.Charge storage layer is the structure of comparison core in nonvolatile memory (non-volatile memory); Non-volatile read-only memory device, for example ROS (ROM), programmable read-only memory (prom), Erasable Programmable Read Only Memory EPROM (EPROM) and other the more non-volatile read-only memory device of high-grade be widely used in fields such as mobile phone, notebook computer, palm PC, digital camera.
To specify the making method of ONO structure in the prior art below:
At first, on wafer substrate, said wafer substrate comprises electric charge storage region and peripheral circuit region, and oxygen and material are that the substrate of silicon at high temperature reacts generation silicon-dioxide (SiO
2) upper layer, SiO
2Thickness accurately control by temperature and time.
Next, adopt the method for chemical vapor deposition (CVD), at said SiO
2Form silicon nitride layer on the upper layer, silicon nitride layer is a mask layer, and thickness is generally thinner, and is thick such as the 100 Izod right sides.
In this process, also can adopt the method for plasma enhanced chemical vapor deposition (PECVD).
At last, form silicon oxynitride with wet oxygen (wet oxide) forced oxidation silicon nitride layer, (High Temperature Oxide HTO), constitutes top layer zone of oxidation (Top Oxide) to deposit one deck high-temperature oxide layer on silicon oxynitride jointly.Wherein, the thickness of HTO layer is between 100 dust to 150 dusts, and it is right to be preferably 120 Izods.
Likewise, when adopting silicon to aim at silicide method formation gate lateral wall blocking layer, also need generate the high-temperature oxide layer sometimes, the method that forms the high-temperature oxide layer is identical with aforesaid method.
When forming the high-temperature oxide layer according to the method described above, use silane (SiH usually
4) and nitrous oxide (N
2O) reaction adopts the method for low-pressure chemical vapor deposition (LPCVD) to obtain.When concrete the realization, a plurality of wafers that will deposit the high-temperature oxide layer are placed in the brilliant boat, are placed in the brilliant boat such as 50 wafer, and the fringe region of wafer and brilliant boat internal surface contact.In brilliant boat, feed SiH
4And N
2O reacts; Because speed of response is fast, and fully be exposed to the brilliant boat rough inner surface in the gas, the surface-area of the crystal round fringes zone contact with gas that causes being placed diminishes relatively; Make the speed of deposition high-temperature oxide layer slack-off; Thereby the high-temperature oxide layer attenuation that the crystal round fringes zone is formed, and the high-temperature oxide layer of crystal circle center's area deposition is thicker, the uniformity of high-temperature oxide that causes the wafer deposition to obtain reduces.
According to prior art after forming the high-temperature oxide layer on the wafer; Adopt wafer acceptance (WAT, Wafer Accept Test) method to test electrical thickness and learn, its homogeneity is 4.70% at brilliant boat vertex; Valley is 4.90%; Intermediate point is 4.50%, and homogeneity is bad, and the performance of semiconductor device that causes finally obtaining reduces.
Summary of the invention
In view of this, the present invention provides a kind of method that improves the uniformity of high-temperature oxide of wafer, this method solve wafer the not high problem of sedimentary uniformity of high-temperature oxide.
For achieving the above object, the technical scheme of the embodiment of the invention specifically is achieved in that
A kind of method that improves the uniformity of high-temperature oxide of wafer comprises:
In not placing the brilliant boat of wafer, continue to feed the gas that forms the high-temperature oxide layer, up to form the high-temperature oxide layer of thickness at this crystalline substance boat internal surface more than or equal to 20000 dusts;
The multi-disc wafer is put into this crystalline substance boat, deposit high-temperature oxide layer.
The gas of said formation high-temperature oxide layer is silane SiH
4With nitrous oxide gas N
2O.
Before this method, also comprise:
This crystalline substance boat is cleaned.
Said this crystalline substance boat is cleaned adopted dense hydrofluoric acid.
Said hydrofluoric acid concentration be more than or equal to 40%, the time length was more than or equal to 20 minutes.
Said dense hydrofluoric acid concentration equal 49%, the time length was more than or equal to 30 minutes.
The said thickness that on this crystalline substance boat internal surface, forms more than or equal to the process of the high-temperature oxide layer of 20000 dusts is:
Adopt single test, in this test, in brilliant boat, put into wafer deposition high-temperature oxide layer, measurement is write down when sedimentary thickness is more than or equal to 20000 dusts on wafer and is fed gas dosage and the reaction times that forms the high-temperature oxide layer;
During the said gas that in not placing the brilliant boat of wafer, continue to feed forms the high-temperature oxide layer, the gas dosage and the reaction times of using the feeding of being write down to form the high-temperature oxide layer form the high-temperature oxide layer of thickness more than or equal to 20000 dusts at brilliant boat internal surface.
Visible by technique scheme; Before method provided by the invention makes the wafer deposition high-temperature oxide layer that is placed on brilliant boat; In not placing the brilliant boat of wafer, feed the gas that forms the high-temperature oxide layer earlier, up on brilliant boat, forming the high-temperature oxide layer of thickness more than or equal to 20000 dusts.Like this; When the wafer deposition high-temperature oxide layer of brilliant boat; Will make the brilliant boat internal surface that is exposed in the gas that forms high temperature oxide layer become smooth; Cause the surface-area of follow-up crystal round fringes zone contact with gas of placing to become big relatively, thereby when deposition, form and the corresponding to high-temperature oxide layer of crystal circle center's area thickness homogeneity.Further; In not placing the brilliant boat of wafer, feed before the gas that forms the high-temperature oxide layer; Can also brilliant boat that not place wafer be put into dense hydrofluoric acid (DHF) cleans; Clean brilliant boat internal surface and make it smooth, thereby the surface-area of surface-area that makes the crystal round fringes zone contact gas that feeds and the crystal circle center regional gas that feeds is consistent.Therefore, this method just improved wafer the homogeneity of sedimentary high-temperature oxide layer.
Description of drawings
Fig. 1 is the method flow diagram of the uniformity of high-temperature oxide of raising wafer provided by the invention.
Embodiment
For making the object of the invention, technical scheme and advantage clearer, below with reference to the accompanying drawing embodiment that develops simultaneously, the present invention is done further explain.
Can find out that from prior art the not high reason of uniformity of high-temperature oxide that causes on wafer, forming is: the gas reaction of placing on the one hand the formation high-temperature oxide layer that the brilliant boat of wafer feeds is than very fast; Be brilliant boat rough inner surface on the other hand; And causing the surface-area of the crystal round fringes zone contact gas that feeds to diminish relatively, the high-temperature oxide that the gas reaction that feeds obtains in the relatively shorter time can not be deposited on crystal round fringes zone and crystal circle center zone equably.
In order to address this problem; Before method provided by the invention makes the wafer deposition high-temperature oxide layer that is placed on brilliant boat; In not placing the brilliant boat of wafer, feed the gas that forms the high-temperature oxide layer earlier; Up on brilliant boat, forming the high-temperature oxide layer, the thickness of this high-temperature oxide layer makes brilliant boat internal surface become level and smooth more than or equal to 20000 dusts.Like this; Just can avoid in the prior art; Crystal round fringes is regional because brilliant boat rough inner surface makes the surface-area of the contact gas that feeds diminish relatively, and the gas reaction ratio of formation high-temperature oxide layer is very fast, and within a short period of time is than the slow problem of the regional formed high-temperature oxide layer of crystal circle center; Guarantee that crystal round fringes zone and the gas that is fed fully react, deposition obtains the higher high-temperature oxide layer of homogeneity on wafer.
Further; The present invention feeds in not placing the brilliant boat of wafer before the gas that forms the high-temperature oxide layer, can also improve the surface-area of the crystal round fringes zone contact gas that feeds through cleaning step, such as feeding DHF; Concentration is more than or equal to 40%; Be preferably 49% or 45%, the time of feeding was preferably 30 minutes or 35 minutes more than or equal to 20 minutes.Like this; Cleaning brilliant boat internal surface makes it smooth; Improve the surface-area area of the crystal round fringes zone contact gas that feeds; It is identical to guarantee that high-temperature oxide that institute's gas that feeds generates is deposited upon crystal round fringes ability regional and that crystal circle center is regional, on wafer, obtains the higher high-temperature oxide layer of homogeneity.
Fig. 1 is the method flow diagram of the uniformity of high-temperature oxide of raising wafer provided by the invention, and its concrete steps are:
In this step, to clean and adopt DHF, the concentration of use is more than or equal to 40%, is preferably 49%, the time is more than or equal to 20 minutes, is preferably 30 minutes.
In this step, the gas that forms the high-temperature oxide layer is SiH
4And N
2O, the method for employing is LPCVD.
In this step; Formation thickness more than or equal to the method for the high-temperature oxide layer of 20000 dusts is: adopt single test; In this test; In brilliant boat, put into a wafer, according to prior art deposition high-temperature oxide layer, record feeds gas dosage and the reaction times that forms the high-temperature oxide layer when measuring thickness more than or equal to 20000 dusts then; And then to the multi-disc wafer when the brilliant boat deposition, just can use gas dosage and reaction times that the feeding of being write down forms the high-temperature oxide layer at the high-temperature oxide layer of brilliant boat internal surface formation thickness more than or equal to 20000 dusts.
In this step, formed high-temperature oxide layer is exactly a silicon oxide layer.
In the present invention, place the brilliant boat of wafer and can place the multi-disc wafer simultaneously,, be multi-disc wafer deposition high-temperature oxide layer simultaneously such as 50.
The present invention deposits the high-temperature oxide layer on wafer method can be applied in making ONO structure or adopt the self-aligned silicide method to form the gate lateral wall blocking layer.
According to the method that forms the method for thicker high-temperature oxide layer at brilliant boat internal surface, improves the surface-area of the crystal round fringes zone contact gas that feeds through cleaning step of the present invention, reach the described method of Fig. 1 after depositing the high-temperature oxide layer on the wafer; Adopting WAT to carry out electrical thickness measurement learns; The homogeneity of the high-temperature oxide layer of its formation is compared with prior art, and raising is all arranged.Wherein, for the method that forms thicker high-temperature oxide layer at brilliant boat internal surface, its homogeneity is 3.10% at brilliant boat vertex, and valley is 3.30%, and intermediate point is 3.00%; For the method for the surface-area that improves the contact gas that feeds in crystal round fringes zone through cleaning step, its homogeneity is 3.20% at brilliant boat vertex, and valley is 3.10%, and intermediate point is 3.50%; For the described method of Fig. 1, its homogeneity is 2..50% at brilliant boat vertex, and valley is 2.80%, and intermediate point is 2.90%.Can find out; The uniformity of high-temperature oxide that adopts the described method of Fig. 1 to obtain is best; Be employed in the uniformity of high-temperature oxide that method that brilliant boat internal surface forms thicker high-temperature oxide layer obtains and take second place, improve the method for the surface-area of the crystal round fringes zone contact gas that feeds through cleaning step and take second place again.
Therefore, method provided by the invention has improved the uniformity of high-temperature oxide that the wafer deposition obtains, thereby has improved the performance of semiconductor device that finally obtains.
More than lift preferred embodiment; The object of the invention, technical scheme and advantage have been carried out further explain, and institute it should be understood that the above is merely preferred embodiment of the present invention; Not in order to restriction the present invention; All within spirit of the present invention and principle, any modification of being done, be equal to replacement and improvement etc., all should be included within protection scope of the present invention.
Claims (6)
1. method that improves the uniformity of high-temperature oxide of wafer comprises:
In not placing the brilliant boat of wafer, continue to feed the gas that forms the high-temperature oxide layer, up to form the high-temperature oxide layer of thickness at this crystalline substance boat internal surface more than or equal to 20000 dusts;
The multi-disc wafer is put into this crystalline substance boat, deposit high-temperature oxide layer;
Saidly form thickness at this crystalline substance boat internal surface and be more than or equal to the process of the high-temperature oxide layer of 20000 dusts:
Adopt single test, in this test, in brilliant boat, put into wafer deposition high-temperature oxide layer, measurement is write down when sedimentary thickness is more than or equal to 20000 dusts on wafer and is fed gas dosage and the reaction times that forms the high-temperature oxide layer;
During the said gas that in not placing the brilliant boat of wafer, continue to feed forms the high-temperature oxide layer, the gas dosage and the reaction times of using the feeding of being write down to form the high-temperature oxide layer form the high-temperature oxide layer of thickness more than or equal to 20000 dusts at brilliant boat internal surface.
2. the method for claim 1 is characterized in that, the gas of said formation high-temperature oxide layer is silane SiH
4With nitrous oxide gas N
2O.
3. the method for claim 1 is characterized in that, before this method, also comprises:
This crystalline substance boat is cleaned.
4. method as claimed in claim 3 is characterized in that, said this crystalline substance boat is cleaned adopted dense hydrofluoric acid.
5. method as claimed in claim 4 is characterized in that, said dense hydrofluoric acid concentration be more than or equal to 40%, the time length was more than or equal to 20 minutes.
6. method as claimed in claim 4 is characterized in that, said hydrofluoric acid concentration equal 49%, the time length was more than or equal to 30 minutes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009100533768A CN101928934B (en) | 2009-06-18 | 2009-06-18 | Method for improving uniformity of high-temperature oxide of wafer |
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|---|---|---|---|
| CN2009100533768A CN101928934B (en) | 2009-06-18 | 2009-06-18 | Method for improving uniformity of high-temperature oxide of wafer |
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| Publication Number | Publication Date |
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| CN101928934A CN101928934A (en) | 2010-12-29 |
| CN101928934B true CN101928934B (en) | 2012-11-28 |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1765005A (en) * | 2003-03-28 | 2006-04-26 | 圣戈本陶瓷及塑料股份有限公司 | Wafer carrier having improved processing characteristics |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1765005A (en) * | 2003-03-28 | 2006-04-26 | 圣戈本陶瓷及塑料股份有限公司 | Wafer carrier having improved processing characteristics |
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| CN101928934A (en) | 2010-12-29 |
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Effective date of registration: 20121116 Address after: 201203 Shanghai City, Pudong New Area Zhangjiang Road No. 18 Patentee after: Semiconductor Manufacturing International (Shanghai) Corporation Patentee after: Semiconductor Manufacturing International (Beijing) Corporation Address before: 201203 Shanghai City, Pudong New Area Zhangjiang Road No. 18 Patentee before: Semiconductor Manufacturing International (Shanghai) Corporation |
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