The optimization method of chemical mechanical milling tech
Technical field
The present invention relates to field of semiconductor manufacture, particularly a kind of optimization method of chemical mechanical milling tech.
Background technology
Along with the extensive use of electronic equipment, semi-conductive manufacturing process has obtained development at full speed, in semi-conductive manufacturing process, relates to cmp (CMP) technology.Since the mid-90 in 20th century, CMP technology has become the smooth technology of a kind of main surface globalization, and it comes the planarization crystal column surface through the relative motion between wafer and the rubbing head.
In practical application, for CMP technology is optimized, usually need be under different CMP technological parameters; For example adopt different polishing speed or adopt different polishing liquid; Laboratory sample is ground, after grinding finishes, the parameter of experiments of measuring sample; If the parameter of laboratory sample does not reach technological standards, then adjust the CMP technological parameter to reach the purpose of optimizing CMP technology.Need to prove that CMP technology can be applicable to some processing procedures, to the optimization of the CMP technology in the different processing procedures; Laboratory sample is inequality; The parameter of the laboratory sample that need measure is also inequality, for example, if the CMP technology in the tungsten plug processing procedure is optimized; One of them key parameter of the laboratory sample that then need measure is the height of tungsten plug; Said height is the relative altitude of tungsten plug, and promptly the upper surface of tungsten plug is with respect to the height of oxide layer upper surface, if the CMP technology in shallow channel isolation area (STI) processing procedure is optimized; One of them key parameter of the laboratory sample that then need measure is the degree of depth of oxide depression in the shallow trench, and the degree of depth of said depression is for silicon nitride (SiN) layer.
Being example with CMP process optimization method in the tungsten plug processing procedure of prior art and the STI processing procedure respectively below describes the optimization method of CMP technology.
CMP process optimization method may further comprise the steps in the tungsten plug processing procedure of prior art:
Step 1; Fig. 1 is the generalized section of the step 1 of CMP process optimization method in the tungsten plug processing procedure of prior art, referring to Fig. 1, a laboratory sample is provided; This laboratory sample is for being filled with the wafer of tungsten in the through hole of oxide layer; After adopting CMP technology that tungsten is ground to the oxide layer surface and forms the tungsten plug, adopt electron beam deposition technology to form tungsten on the oxide layer surface, it is right that the thickness of the tungsten that forms through electron beam deposition technology is about 300 Izods.
Electron beam deposition technology belongs to a kind of in the chemical vapor deposition (CVD) technology; Have diverse structure and characteristic through the tungsten of electron beam deposition technology formation and the tungsten in the tungsten plug; The principle of electron beam deposition technology is the surface that tungsten is deposited on another film with the form of tungsten electron beam; In this step, another film is an oxide layer.
Need to prove that for the CMP technology in the tungsten plug processing procedure is optimized, the parameter that needs to measure is the height of tungsten plug; Because the tungsten plug is arranged in the through hole of oxide layer, for the height of tungsten plug is measured, need cut according to crown direction the tungsten plug; Obtaining the longitudinal section of tungsten plug, thereby can measure the height of tungsten plug according to the longitudinal section of tungsten plug, if but directly tungsten is filled in the row cutting; Damage the tungsten plug easily, the height of measured like this tungsten plug is inaccurate, therefore; In the prior art, the method that adopts usually is on oxide layer, to cover two-layer material different again, to form the stepped construction of cake shape; Thereby can cut the stepped construction of cake shape, measure the height of tungsten plug according to the longitudinal section that is obtained.What obtain according to the cutting of crown direction is coronal-plane; Coronal-plane is along left and right directions object to be divided into forward and backward two-part vertical section; Coronal-plane and horizontal plane and sagittal plane are orthogonal; As if what obtain according to the sagittal direction cutting is sagittal plane, and sagittal plane is along fore-and-aft direction object to be divided into left and right two-part vertical section, and sagittal plane and horizontal plane and coronal-plane are orthogonal.
In addition, method of the present invention is ground laboratory sample under current CMP technological parameter to laboratory sample, and the parameter of experiments of measuring sample, so that the CMP technological parameter is optimized.
Step 2; Fig. 2 is the generalized section of the step 2 of CMP process optimization method in the tungsten plug processing procedure of prior art, referring to Fig. 2, adopts ion beam depositing technology to form tungsten; The tungsten that forms through ion beam depositing technology is positioned at the surface through the tungsten of electron beam deposition technology formation; It is right that the thickness of the tungsten that forms through ion beam depositing technology is about 3000 Izods, according to crown direction laboratory sample is cut then, thus the longitudinal section that obtains laboratory sample.
The principle of ion beam depositing technology is that tungsten is deposited on the surface of another film with the form of tungsten ion bundle, and in this step, another film is the tungsten that forms through electron beam deposition technology.
Tungsten plug, all different in appearance through electron beam deposition technology tungsten that forms and the tungsten that forms through ion beam depositing technology; Be convenient in follow-up step, from the longitudinal section of laboratory sample, measure the height of tungsten plug; And the tungsten that forms through electron beam deposition technology and the tungsten that forms through ion beam depositing technology all have certain rigidity, is convenient to cutting.
Step 3, the height of tungsten plug if the height of tungsten plug does not satisfy technological standards, is then adjusted current CMP technological parameter, and is repeated step 1 and step 2 in the longitudinal section of employing transmission electron microscope (TEM) experiments of measuring sample; If the height of tungsten plug satisfies technological standards, then process ends.
Operating personnel can adopt TEM that the longitudinal section of laboratory sample is observed; And from the visual field of TEM, estimate the height of tungsten plug, perhaps, accurate for more; Also can adopt TEM that the image taking of the longitudinal section of laboratory sample is got off, adopt image process method to measure the height of tungsten plug then.
If the height of tungsten plug is less than technological standards; Can attempt increasing the milling time on the CMP grinding table 3 (platent3); If the height of tungsten plug greater than technological standards, can attempt reducing the time of the grinding on the CMP grinding table 3 (platent3), also can recently regulate the height of tungsten plug through adopting different choice; Wherein, select the ratio of ratio for the rate that removes of the rate that removes of tungsten plug and oxide layer.
So far, this flow process finishes.
CMP process optimization method may further comprise the steps in the STI processing procedure of prior art:
Step 1; Fig. 3 is the generalized section of the step 1 of CMP process optimization method in the STI processing procedure of prior art, referring to Fig. 3, a laboratory sample is provided; This laboratory sample is for being filled with the wafer of oxide in the shallow trench of SiN layer; After adopting CMP technology that oxide is ground to the SiN laminar surface, adopt electron beam deposition technology to form tungsten at the SiN laminar surface, it is right that the thickness of the tungsten that forms through electron beam deposition technology is about 300 Izods.
For the CMP technology in the STI processing procedure is optimized, the parameter that needs to measure is the degree of depth of oxide depression in the shallow trench.
Step 2; Fig. 4 is the generalized section of the step 2 of CMP process optimization method in the STI processing procedure of prior art, referring to Fig. 4, adopts ion beam depositing technology to form tungsten; The tungsten that forms through ion beam depositing technology is positioned at the surface through the tungsten of electron beam deposition technology formation; It is right that the thickness of the tungsten that forms through ion beam depositing technology is about 3000 Izods, according to crown direction laboratory sample is cut then, thus the longitudinal section that obtains laboratory sample.
Oxide in the shallow trench, all different in appearance through electron beam deposition technology tungsten that forms and the tungsten that forms through ion beam depositing technology; Be convenient in follow-up step, from the longitudinal section of laboratory sample, measure the degree of depth of the oxide depression in the shallow trench; And the tungsten that forms through electron beam deposition technology and the tungsten that forms through ion beam depositing technology all have certain rigidity, is convenient to cutting.
Step 3 adopts TEM to measure the degree of depth of oxide depression in the shallow trench, if the degree of depth of oxide depression does not satisfy technological standards in the shallow trench, then adjusts current CMP technological parameter, and repeats step 1 and step 2; If the degree of depth of oxide depression satisfies technological standards in the shallow trench, then process ends.
If the degree of depth of oxide depression is greater than technological standards in the shallow trench, can attempts reducing the throwing time excessively on the CMP grinding table 2 (platent2), or adopt other suitable lapping liquids etc.
So far, this flow process finishes.
Yet; In practical application, the composition of oxide layer might be ethyl orthosilicate silica (TEOS) or high depth-to-width ratio silicon oxide (HARP), and the composition of oxide might be TEOS or HARP in the shallow trench; When adopting TEOS or HARP as the oxide in oxide layer or the shallow trench; Since the characteristic of TEOS or HARP itself can cause when TEOS or HARP when tungsten through the formation of electron beam deposition technology contacts, TEOS and HARP surface all can produce shrinkage phenomenon, thereby make the oxide in oxide layer or the shallow trench cave in; In this case; The degree of depth of oxide depression can not reflect the effect of CMP technology truly in the height of measured tungsten plug or the shallow trench, therefore, also just is difficult to CMP technology is realized optimizing.
Summary of the invention
In view of this, the present invention provides a kind of optimization method of chemical mechanical milling tech, can be optimized CMP technology.
For achieving the above object, technical scheme of the present invention specifically is achieved in that
A kind of optimization method of chemical mechanical milling tech, this method comprises:
A, a laboratory sample is provided, and after according to current cmp CMP technological parameter laboratory sample being carried out CMP technology, using plasma strengthens chemical vapour deposition (CVD) PE-CVD technology and forms silicon nitride SiN on the laboratory sample surface;
B, employing ion beam depositing technology form tungsten on the surface of SiN, according to crown direction laboratory sample are cut then, and obtain the longitudinal section of laboratory sample;
The parameter of laboratory sample if the parameter of laboratory sample does not satisfy technological standards, is then adjusted current CMP technological parameter in the longitudinal section of C, employing transmission electron microscope TEM experiments of measuring sample, and execution in step A; If the parameter of laboratory sample satisfies technological standards, then process ends.
Said laboratory sample is for being filled with the wafer of tungsten in the through hole of oxide layer;
The parameter of said laboratory sample is the height of tungsten plug.
Said laboratory sample is for being filled with the wafer of oxide in the shallow trench of SiN layer;
The parameter of said laboratory sample is the degree of depth of oxide depression in the shallow trench.
The thickness of said SiN is 800 dust to 1600 dusts.
It is thus clear that; The optimization method of chemical mechanical milling tech provided by the present invention comprises: A, a laboratory sample is provided; And after according to current cmp CMP technological parameter laboratory sample being carried out CMP technology, using plasma strengthens chemical vapour deposition (CVD) PE-CVD technology and forms silicon nitride SiN on the laboratory sample surface; B, employing ion beam depositing technology form tungsten on the surface of SiN, according to crown direction laboratory sample are cut then, and obtain the longitudinal section of laboratory sample; The parameter of laboratory sample if the parameter of laboratory sample does not satisfy technological standards, is then adjusted current CMP technological parameter in the longitudinal section of C, employing transmission electron microscope TEM experiments of measuring sample, and execution in step A; If the parameter of laboratory sample satisfies technological standards, then process ends like this, just can be measured the parameter of laboratory sample accurately, can realize the optimization of CMP technology.
Description of drawings
Fig. 1 is the generalized section of the step 1 of CMP process optimization method in the tungsten plug processing procedure of prior art.
Fig. 2 is the generalized section of the step 2 of CMP process optimization method in the tungsten plug processing procedure of prior art.
Fig. 3 is the generalized section of the step 1 of CMP process optimization method in the STI processing procedure of prior art.
Fig. 4 is the generalized section of the step 2 of CMP process optimization method in the STI processing procedure of prior art.
Fig. 5 is the flow chart of the optimization method of a kind of CMP technology provided by the present invention.
Fig. 6 is the generalized section of the step 1 of CMP process optimization method in the tungsten plug processing procedure provided by the present invention.
Fig. 7 is the generalized section of the step 2 of CMP process optimization method in the tungsten plug processing procedure provided by the present invention.
Fig. 8 is the generalized section of the step 1 of CMP process optimization method in the STI processing procedure provided by the present invention.
Fig. 9 is the generalized section of the step 2 of CMP process optimization method in the STI processing procedure provided by the present invention.
The specific embodiment
For making the object of the invention, technical scheme and advantage clearer, below with reference to the accompanying drawing embodiment that develops simultaneously, to further explain of the present invention.
Core concept of the present invention is: after according to current CMP technological parameter laboratory sample being carried out CMP technology; On laboratory sample, form SiN; Adopt ion beam depositing technology on SiN, to form tungsten again; Then according to crown direction to laboratory sample cutting and obtain the longitudinal section, adopt the parameter of TEM experiments of measuring sample at last, because SiN can't cause the laboratory sample surface to shrink phenomenon with surperficial contact of laboratory sample; Can obtain the parameter of laboratory sample accurately, thereby can be optimized CMP technology.
Fig. 5 is the flow chart of the optimization method of a kind of CMP technology provided by the present invention, and is as shown in Figure 5, and this method comprises:
Step 501 provides a laboratory sample, and after according to current CMP technological parameter laboratory sample being carried out CMP technology, using plasma strengthens chemical vapour deposition (CVD) (PE-CVD) technology and forms SiN on the laboratory sample surface.
Step 502 adopts ion beam depositing technology to form tungsten on the surface of SiN, according to crown direction laboratory sample is cut then, and obtains the longitudinal section of laboratory sample.
Step 503, the parameter of laboratory sample if the parameter of laboratory sample does not satisfy technological standards, is then adjusted current CMP technological parameter in the longitudinal section of employing TEM experiments of measuring sample, and repeated execution of steps 501; If the parameter of laboratory sample satisfies technological standards, then process ends.
Through two embodiment the optimization method of CMP technology is elaborated below.
Embodiment one
CMP process optimization method comprises in the tungsten plug processing procedure provided by the present invention:
Step 1; Fig. 6 is the generalized section of the step 1 of CMP process optimization method in the tungsten plug processing procedure provided by the present invention; Referring to Fig. 6, a laboratory sample is provided, this laboratory sample is for being filled with the wafer of tungsten in the through hole of oxide layer; Adopt CMP technology that tungsten is ground to the oxide layer surface and after forming the tungsten plug, adopts PE-CVD technology to form SiN on the oxide layer surface.
The principle of PE-CVD is to utilize low temperature plasma as energy source; Laboratory sample is placed on the negative electrode of glow discharge under the low pressure; Utilize glow discharge to make laboratory sample be warmed up to predetermined temperature; Feed the reacting gas that adapts to then, gas forms SiN on the laboratory sample surface after series of chemical and plasma reaction.
The thickness of the SiN that forms through PE-CVD technology is 800 dust to 1600 dusts.
The formation method of laboratory sample is: at first on oxide layer, adopt photoetching process to form figure, adopt etch process to form groove then, plated metal tungsten covers all through holes and the surface of oxide layer again.
In this step, adopt SiN to replace the tungsten that forms through electron beam deposition technology of the prior art, can know through experiment; When adopting TEOS or HARP as oxide layer; TEOS and HARP all can not produce shrinkage phenomenon, when the material that adopts other types during as oxide layer, do not produce shrinkage phenomenon yet; The tungsten that SiN forms with the tungsten plug, through ion beam depositing technology in appearance is all different; Be convenient in follow-up step, from the longitudinal section of laboratory sample, measure the height of tungsten plug, and SiN also has certain rigidity, be convenient in subsequent step cutting laboratory sample; Therefore, adopt SiN to replace the tungsten that forms through electron beam deposition technology of the prior art to not influence of experimental result.
Step 2; Fig. 7 is the generalized section of the step 2 of CMP process optimization method in the tungsten plug processing procedure provided by the present invention, referring to Fig. 7, adopts the surface deposition tungsten of ion beam depositing technology at SiN; According to crown direction laboratory sample is cut then, and obtain the longitudinal section.
The thickness of the tungsten that forms through ion beam depositing technology is identical with prior art.
Step 3, the height of tungsten plug if the height of tungsten plug does not satisfy technological standards, is then adjusted current CMP technological parameter, and is repeated step 2 and step 3 in the longitudinal section of employing TEM experiments of measuring sample; If the height of tungsten plug satisfies technological standards, then process ends.
If the height of tungsten plug is less than technological standards; Can attempt increasing the milling time on the CMP grinding table 3 (platent3); If the height of tungsten plug greater than technological standards, can attempt reducing the time of the grinding on the CMP grinding table 3 (platent3), also can recently regulate the height of tungsten plug through adopting different choice; Wherein, select the ratio of ratio for the rate that removes of the rate that removes of tungsten plug and oxide layer.
Step 2 and step 3 are the content of prior art, do not repeat them here.
So far, this flow process finishes.
Thus it is clear that, in embodiment one provided by the present invention, after tungsten is ground to oxide layer surface and forms the tungsten plug; Adopt PE-CVD technology to form SiN, adopt the surface deposition tungsten of ion beam depositing technology again, and cut according to crown direction at SiN on the oxide layer surface; Adopt TEM to measure the height of tungsten plug in the longitudinal section at last; Like this, even adopt TEOS or the HARP main component as oxide layer, the surface of oxide layer does not contact with SiN can cause shrinkage phenomenon; Help obtaining the height of tungsten plug accurately, and then can optimize the CMP technology of tungsten plug.
Embodiment two
CMP process optimization method comprises in the STI processing procedure provided by the present invention:
Step 1; Fig. 8 is the generalized section of the step 1 of CMP process optimization method in the STI processing procedure provided by the present invention; Referring to Fig. 8, a laboratory sample is provided, this laboratory sample is for being filled with the wafer of oxide in the shallow trench of SiN layer; Employing CMP technology is ground to the SiN laminar surface with oxide and after forming STI, adopts PE-CVD technology to form SiN at the SiN laminar surface.
It is right that the thickness of the SiN that forms through PE-CVD technology is about 800 dust to 1600 Izods.
The formation method of laboratory sample is: at first on the SiN layer, adopt photoetching process to form figure, adopt etch process to form groove then, deposition oxide covers all grooves and the surface of SiN layer again.
In this step, adopt SiN to replace the tungsten that forms through electron beam deposition technology of the prior art, can know through experiment; When adopting TEOS or HARP as the oxide in the shallow trench; TEOS and HARP all can not produce shrinkage phenomenon, when the material that adopts other types during as the oxide in the shallow trench, do not produce shrinkage phenomenon yet; SiN in appearance with shallow trench in oxide, the tungsten that forms through ion beam depositing technology all different; Be convenient in follow-up step, from the longitudinal section of laboratory sample, measure the height of the oxide in the shallow trench, and SiN also has certain rigidity, be convenient in subsequent step cutting laboratory sample; Therefore, adopt SiN to replace the tungsten that forms through electron beam deposition technology of the prior art to not influence of experimental result.
Step 2; Fig. 9 is the generalized section of the step 2 of CMP process optimization method in the STI processing procedure provided by the present invention, referring to Fig. 9, adopts the surface deposition tungsten of ion beam depositing technology at SiN; According to crown direction laboratory sample is cut then, and obtain the longitudinal section of laboratory sample.
The thickness of the tungsten that forms through ion beam depositing technology is identical with prior art.
Step 3 adopts TEM to measure the degree of depth of oxide depression in the shallow trench, if the degree of depth of oxide depression does not satisfy technological standards in the shallow trench, then adjusts current CMP technological parameter, and repeats step 2 and step 3; If the degree of depth of oxide depression satisfies technological standards in the shallow trench, then process ends.
If the degree of depth of oxide depression is greater than technological standards in the shallow trench, can attempts reducing the throwing time excessively on the CMP grinding table 2 (platent2), or adopt other suitable lapping liquids etc.
Step 2 and step 3 are the content of prior art, do not repeat them here.
So far, this flow process finishes.
Thus it is clear that, in embodiment two provided by the present invention, after the oxide in the shallow trench is ground to the SiN laminar surface and forms STI; Adopt PE-CVD technology to form SiN, adopt the surface deposition tungsten of ion beam depositing technology again, and cut according to crown direction at SiN at the SiN laminar surface; Adopt TEM to measure the degree of depth of the oxide depression in the shallow trench at last; Like this, even adopt TEOS or the HARP main component as oxide in the shallow trench, the surface of oxide does not contact with SiN and can cause shrinkage phenomenon in the shallow trench; Help obtaining the degree of depth of the oxide depression in the shallow trench, and then can optimize the CMP technology of STI.
Provided by the present invention and main distinction prior art is: in the prior art; For the parameter of the laboratory sample after CMP technology is measured; At first adopt electron beam deposition technology on laboratory sample, to form layer of metal tungsten; Adopt ion beam depositing technology to form layer of metal tungsten again; According to crown direction laboratory sample is cut and obtains the longitudinal section of laboratory sample then, adopt the parameter of TEM experiments of measuring sample at last, according to the parameter of laboratory sample to the CMP parameter adjustment; And in the present invention; At first on laboratory sample, form SiN, adopt ion beam depositing technology to form tungsten again, according to crown direction laboratory sample is cut and obtain the longitudinal section then; Adopt the parameter of TEM experiments of measuring sample at last; So just can avoid the surface of laboratory sample to shrink phenomenon, can obtain the parameter of laboratory sample accurately, thereby reach the purpose of optimizing CMP technology.
The above is merely preferred embodiment of the present invention, is not to be used to limit protection scope of 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.