Summary of the invention
The technical problem that the present invention will solve is to adopt conventional photoresistance to realize the formation of the above top-level metallic of 6um and solve the accurate problem of mistake that causes owing to thickness and the interference of metal lines
For solving the problems of the technologies described above, the present invention provides a kind of formation method of top-level metallic, comprising:
Substrate is provided, has the metal connecting line district on the said substrate;
On said substrate, form the barrier layer, said barrier layer exposes said metal connecting line district;
Form metal level, said metal level comprises the first district's metal level that covers said metal connecting line district, and covers second district's metal level on said barrier layer, and wherein, the surface of first district's metal level is lower than the surface of second district's metal level;
Form first photoresist layer, said first photoresist layer covers said first district's metal level and second district's metal level;
Lithography alignment is carried out on the surface that is lower than second district's metal level based on the surface of first district's metal level, and said first photoresist layer is carried out photoetching;
With first photoresist layer after the photoetching is mask, and etching second district's metal level forms top-level metallic.
Further, for the formation method of said top-level metallic, after forming top-level metallic, also comprise the steps:
Remove first photoresist layer after the photoetching;
Form passivation layer, said passivation layer covers top-level metallic and barrier layer;
Form second photoresist layer, said second photoresist layer covers said passivation layer;
Further, for the formation method of said top-level metallic, the thickness of said second photoresist layer is less than 5um.
Further, for the formation method of said top-level metallic, said barrier layer thickness is 2~6um.
Further, for the formation method of said top-level metallic, said metal connecting line district comprises: the metal dielectric layer between a plurality of tungsten passages and a plurality of tungsten passage.
Further, for the formation method of said top-level metallic, the material on said barrier layer is silicon dioxide and/or silicon nitride.
Further, for the formation method of said top-level metallic, the thickness of said top-level metallic is greater than 6um.
Compared with prior art, the formation method of top-level metallic provided by the invention owing to form earlier one deck barrier layer, makes step difference diminish, and covering device is surperficial fully thereby make the photoresistance of follow-up formation.
On the other hand; Lithography alignment is carried out on the surface that is lower than second district's metal level based on the surface of first district's metal level; Make alignment procedures can not be affected, avoided the defective that possibly occur qualitatively owing to metal lines and thickness increase the light transmission variation that is caused.
Embodiment
Below in conjunction with accompanying drawing and specific embodiment the formation method of top-level metallic of the present invention is done further explain.According to following explanation and claims, advantage of the present invention and characteristic will be clearer.What need explanation is, accompanying drawing all adopts the form of simplifying very much, only in order to convenient, the purpose of the aid illustration embodiment of the invention lucidly.
Please refer to Fig. 1, it is the schematic flow sheet of formation method of the top-level metallic of the embodiment of the invention.As shown in Figure 1, the formation method of said top-level metallic comprises the steps:
Step S101 provides substrate, has the metal connecting line district on the said substrate;
Step S102 forms the barrier layer on said substrate, said barrier layer exposes said metal connecting line district;
Step S103 forms metal level, and said metal level comprises the first district's metal level that covers said metal connecting line district, and covers second district's metal level on said barrier layer, and wherein, the surface of first district's metal level is lower than the surface of second district's metal level;
Step S104 forms first photoresist layer, and said first photoresist layer covers said first district's metal level and second district's metal level;
Step S105, lithography alignment is carried out on the surface that is lower than second district's metal level based on the surface of first district's metal level, and said first photoresist layer is carried out photoetching;
Step S106 is a mask with first photoresist layer after the photoetching, and etching second district's metal level forms top-level metallic.
Then, please refer to Fig. 1 and Fig. 2~Figure 10, it is the cross-sectional view of formation method of the top-level metallic of the embodiment of the invention.
As shown in Figure 2, substrate 20 is provided, have metal connecting line district 23 on the said substrate 20.Concrete, said substrate 20 comprises substrate 21, and is formed at the metal dielectric layer 22 in the said substrate 21, is formed with tungsten passage 24 in the said metal dielectric layer 22, the metal dielectric layer 22 between adjacent a plurality of tungsten passages 24 reach constitutes metal connecting line districts 23.
Please refer to Fig. 3, form barrier layer 31, said barrier layer 31 covers said substrate 20, promptly on metal dielectric layer 22 and tungsten passage 24, forms barrier layer 31, and said barrier layer 31 can be silicon dioxide (SiO
2), silicon nitride (SiN) or other insulating properties materials, shown in the thickness on barrier layer 31 be 2~6um.
As shown in Figure 4, form patterned light blockage layer 41 on the said barrier layer 31, wherein; Said patterned light blockage layer 41 is negative photoresistance; The thickness of said patterned light blockage layer 41 is 10000~20000 dusts, has through hole 42 in the patterned light blockage layer 41, exposes barrier layer 31.
Please refer to Fig. 5, the said barrier layer 31 of etching forms through hole 51, and the width of said through hole 51 can reach and expose metal connecting line district, below 23.Simultaneously, remove patterned light blockage layer 41 on the barrier layer 31.
Preferably, in above-mentioned steps, also carry out the measurement of critical dimension depth-width ratio (CD Aspect Ratio), make the critical dimension depth-width ratio more than or equal to 2: 1, to reach technological effect preferably.
Please refer to Fig. 6; In said barrier layer 31 and metal connecting line district 23, form metal level 60, said metal level 60 comprises first district's metal level 62 that covers said metal connecting line district 23 and the second district's metal level 61 that covers said barrier layer 31, wherein; The surface of first district's metal level 62 is lower than the surface of second district's metal level 61; Be that metal level 60 has groove 63, said groove 63 will solve the alignment issues that the above metal level of 6um possibly occur greatly, and this will combine Fig. 7 to be elaborated below.
Please refer to Fig. 7, on metal level, form first photoresist layer 71, carry out photoetching process; Obviously be to need to aim at during its photoetching, yet as a rule, metal can have lines when forming; Disturb thereby can produce the aligning in the photoetching process, in addition, along with the increase of metal level 60 thickness; Light transmittance reduces greatly, and problem that mistake aim at and/or can't aim at occur with regard to being easy to this moment, and the present invention has then solved this problem.Concrete; Lithography alignment is carried out on the surface that is lower than second district's metal level based on the surface of first district's metal level; Promptly according to the aligning object of reference (be similar to the function of align mark) of the groove on the metal level 60 63 as photoetching; Carry out lithography alignment, then said first photoresist layer is carried out photoetching process.Because the accuracy of above-mentioned through hole 41 is assurable, and metal level 60 also is even formation,, thereby can be used as the foundation of aligning so said groove 63 also is to have suitable accuracy.In actual production, a plurality of grooves as shown in Figure 7 63 are arranged on the silicon chip, these regularly arranged grooves 63 have been guaranteed the accuracy of alignment procedures in photoetching process, the problem of having avoided mistake to aim at and/or can't aim at has been guaranteed yield.
Please refer to Fig. 8, through having removed first photoresist layer on second district's metal level 61 after the photoetching process, keep first photoresist layer 71 on first district's metal level 61 '.
Please refer to Fig. 9, is mask with first photoresist layer after the photoetching, and etching is removed the second district metal level, form top-level metallic 60 ', certainly, at formation top-level metallic 60 ' afterwards, first photoresist layer on just removable first district's metal level.Then, continue, form passivation layer 91 with reference to figure 9, said passivation layer 91 cover top-level metallics 60 ' with barrier layer 31, wherein, shown in passivation layer 91 can be that silicon dioxide, silicon nitride or the two combine, other materials with similar quality also can.At this moment, because the existence on barrier layer 31, make top-level metallic 60 ' dwindled with the step difference between the rete (, being barrier layer 31) on every side at this.
Please refer to Figure 10, behind the passivation technology, then can go between etc. top-level metallic; At this moment, need carry out photoetching process earlier, can know by above-mentioned analysis; Because step difference has dwindled, maximum has only 4um usually, and this thickness is obviously in the scope that conventional photoresistance can cover; Then second photoresist layer 101 is covered on the passivation layer 91, passivation layer 91 (top-level metallic 60 ') can occur this moment and be exposed to outer situation, subsequent technique also can carry out smoothly.
Compared with prior art, the formation method of top-level metallic provided by the invention owing to form earlier one deck barrier layer, makes step difference diminish, and covering device is surperficial fully thereby make the photoresistance of follow-up formation.
On the other hand; Because metal level is evenly to form; Lithography alignment is carried out on the surface that can be lower than second district's metal level based on the surface of first district's metal level; Promptly according to the aligning object of reference of the groove on the metal level, thereby make alignment procedures can not receive influence, avoided the defective that possibly occur qualitatively owing to metal lines and thickness increase the light transmission variation that is caused as photoetching.
Obviously, those skilled in the art can carry out various changes and modification to invention and not break away from the spirit and scope of the present invention.Like this, if of the present invention these revise and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these change and modification.