CN101409209A

CN101409209A - Method for cleaning abnormal residual on wafer rear surface after Cu CMP procedure

Info

Publication number: CN101409209A
Application number: CNA200710046837XA
Authority: CN
Inventors: 罗进文; 邢程; 马智勇; 孙涛
Original assignee: Semiconductor Manufacturing International Shanghai Corp
Current assignee: Semiconductor Manufacturing International Shanghai Corp
Priority date: 2007-10-09
Filing date: 2007-10-09
Publication date: 2009-04-15

Abstract

The invention relates to a method for cleaning abnormal residue on the surface of a wafer after Cu CMP processing procedure. The method comprises the steps as follows: the wafer after the Cu CMP processing procedure is put into CTS-100 solution to be cleaned for removing impurity; the wafer is checked further before the next procedure, if the surface of the wafer has no the abnormal residue, the next procedure starts directly; if the surface of the wafer also has the abnormal residue, the wafer is put into cleaning solution with the pH value between 7 and 9 to be cleaned; and the cleaned wafer is processed for next procedure. The method can reduce the cleaning time of the wafer and improve the yield of the wafer.

Description

A kind of cleaning method of Cu CMP processing procedure rear surface abnormal residual of wafer

Technical field

The present invention relates to a kind of cleaning method, relate in particular to a kind of cleaning method at the unusual particulate in the Cu of field of lithography wafer CMP processing procedure rear surface.

Background technology

In the Cu of wafer processing procedure process, behind the wafer process CMP (Chemical Mechanical Polishing, chemico-mechanical polishing), its surface is a lot of impurity under regular meeting is residual, as grinding agent, and unusual granule etc., this just needs the use cleaning fluid come removal of contamination.Existing general way is will justify crystalline substance after grinding to be placed in the CTS-100 solution and to clean, before wafer enters next flow process, just need check wafer, if crystal column surface is clean, there is not impurity, then directly enter next flow process, if the surface of wafer is owing to suffering unusual condition to cause the surface to have particle, will cause product rejection, then can not enter next flow process at once, at this moment just need clean again wafer.Usually we can use CTS-100 solution wafer to be cleaned again again, promptly in whole process, use the CTS-100 cleaning fluid twice.Because the pH value of cleaning fluid has faintly acid between 5～6, in the process of cleaning, will cause the oxide of metal to be corroded like this, and then corroding metal, thereby making that wafer is whole is damaged, and can not have re-used.

Summary of the invention

Technical problem solved by the invention is, a kind of method of new cleaning wafer surface impurity is provided, and more effectively removal of contamination is avoided because of the surface abnormalities residue exceeds standard, and caused scrapping of product, thereby improves the yield of wafer.

The cleaning method of the Cu CMP processing procedure rear surface abnormal residual of a kind of wafer of the present invention comprises,

1), will put into CTS-100 solution the inside and clean removal impurity through the wafer behind the Cu CMP processing procedure;

2), before entering next flow process, further check this wafer, if the surface of wafer does not have abnormal residual, then directly enter next flow process;

3), then wafer is put into pH value and in the cleaning fluid between 7 to 9, cleaned if the surface of wafer also has abnormal residual;

4), the wafer that will clean enters next flow process.

Wherein this cleaning fluid comprises ammoniacal liquor fluoride mixture, organic solvent and water, and this cleaning fluid can be ST250.

The present invention has alkalescent owing to adopted new cleaning fluid, is difficult for corroding with the Cu surface, can effectively remove the impurity of crystal column surface again, improves the yield of wafer.

Description of drawings

Fig. 1 is the flow chart of cleaning wafer surface impurity;

Fig. 2 is the schematic diagram of the wafer that uses original cleaning method and cleaned;

Fig. 3 is the schematic diagram of the wafer that uses cleaning method of the present invention and cleaned;

Fig. 4 is the contrast of the yield of the wafer that uses two kinds of methods and cleaned;

Fig. 5 is time dielectric layer puncture voltage (TDDB) schematic diagram of the wafer that uses original cleaning method and cleaned;

Fig. 6 is time dielectric layer puncture voltage (TDDB) schematic diagram of the wafer that uses existing cleaning method and cleaned.

Embodiment

The present invention is the further improvement that existing cleaning method is made, promptly behind the Cu of wafer CMP processing procedure, use CTS-100 solution that wafer is cleaned earlier, before entering next flow process, wafer is checked, if wafer does not have oxidized, the surface does not have impurity, then directly enters next flow process, if there is abnormal residual impurity on the surface of wafer, then need wafer is done further processing, promptly once clean again, just can enter next flow process then.And the significant improvement that the present invention makes the cleaning fluid in this process just, what this cleaning fluid used is a kind of new alkaline cleaning fluid, its pH value is greatly within 7～9 scope, when so again wafer being cleaned, because this cleaning fluid has alkalescent,, more can not erode metal so this cleaning fluid is difficult to and the oxide reaction of metal, and this can wash other impurity easily, so do the fraction defective that has just significantly reduced wafer like this.

Below in conjunction with a specific embodiment the method applied in the present invention is done a detailed explanation,

Behind the Cu of wafer CMP processing procedure, the surface of wafer often has impurity such as granule, grinding agent, so need wafer be cleaned, detailed process is as follows, as shown in Figure 1,

1, wafer is put into CTS-100 solution the inside and cleaned, be used to remove the crystal column surface remaining impurities;

2, because wafer is needing just to enter next flow process through measuring after website adds inspection after the cleaning, in adding the inspection process, wafer may abnormal conditions occur and cause the surface of wafer impurity to occur, so when wafer enters next flow process, wafer is carried out defect inspection, whether the surface of seeing wafer also has abnormal residual, if no, then directly enter next flow process;

3, if the surface of wafer also has abnormal residual,, then this wafer is put into ST250 solution the inside and cleaned, remove the impurity of crystal column surface;

4, the wafer that will clean directly enters next flow process.

Cleaning the cleaning fluid that is adopted for the second time in this example is ST250, and its main component is NH4-R-F (an ammoniacal liquor fluoride mixture), and proportion is 55%, H2O, proportion are 40%, solvent (organic solvent), proportion is 5%, whole easy one-tenth alkalescent.

Wherein we can regulate the pH value of this cleaning fluid by adjusting the shared proportion of H2O, as long as the pH value that guarantees this cleaning fluid just can be realized the purpose of cleaning between 7～9.

We are also to two kinds of cleaning methods simultaneously, promptly method and the method applied in the present invention that adopts usually now made a contrast, the wafer that existing method was cleaned as shown in Figure 2, the surface is still residual a lot of impurity, and the metal level of wafer is easy to be corroded; The wafer that the present invention cleaned as shown in Figure 3, the surface does not have impurity basically, and the metal level of wafer is not easy to be corroded very much; And the time that original method needs, the present invention then only needed 30s probably at 104s, and the used time has also shortened greatly, has improved operating efficiency.

Utilize method of the present invention to compare with existing way, the yield of wafer has had tangible lifting, as shown in Figure 4, the yield of the cleaning method that now often has adopts method of the present invention 84.60%, and yield can reach 86.10%, improved nearly 1.5 percentage points, this will reduce cost greatly.

Equally, utilize the method applied in the present invention, the wafer that cleaned is carried out actual test 1000 hours, its result shows, stress migration obviously reduces, and electric current also relatively steadily, be not easy to produce big sharp cutting edge of a knife or a sword pulse, its time dielectric breakdown voltage (Time Dependant Deelectric Breakdown, TDDB) index as shown in Figure 6, its effect is more stable, does not produce the breakdown situation of dielectric layer, and the hot operation life-span of its package level (High Temperature Operation Lifetime) is longer.Fig. 5 the breakdown situation of dielectric layer can occur over time for the TDDB test result that existing cleaning method cleans wafer later.

Cleaning method of the present invention can shorten the scavenging period of wafer, and has improved the yield of wafer.

Claims

1, a kind of cleaning method of Cu CMP processing procedure rear surface abnormal residual of wafer is characterized in that, this method comprises,

4), the wafer that will clean enters next flow process.

2, the cleaning method of the Cu CMP processing procedure rear surface abnormal residual of a kind of wafer as claimed in claim 1 is characterized in that described cleaning fluid comprises ammoniacal liquor fluoride mixture, organic solvent and water.

3, the cleaning method of the Cu CMP processing procedure rear surface abnormal residual of a kind of wafer as claimed in claim 1 is characterized in that described cleaning fluid is ST250.