TW523864B - Method for removing micro scratch on metal layer surface - Google Patents

Abstract

A kind of method for removing micro scratch on metal layer surface suitable for use in a dual-metal damascene process is disclosed in the present invention. In the dual-metal damascene process, a conformal barrier layer and a metal layer, which is enough for over filling up the opening, are sequentially formed on the dielectric layer having an opening. The method for removing micro scratch on metal layer surface includes three chemical mechanical polishing (CMP) steps. In the first CMP step, the first slurry, which has a chemical solution and plural grinding particles, is used to grind and remove the metal layer outside the opening. In the second CMP step, the second slurry is used to grind and remove the barrier layer outside the opening, in which plural micro scratches are formed on the metal layer. In the third CMP step, the first slurry is used to buff the metal layer so as to remove micro scratches formed on the metal layer.

Description

523864

The present invention relates to a method for removing the surface of a metal layer from scratches on a metal surface. Method, especially with regard to the background of the invention

In the field of semiconductor technology, wires are made at the metal M. t ^ M9 is used on semiconductor wafers n < patterned with ^ metal wires 4 ϋ + and patterned out-an opening. ί; It includes a thick dielectric shoulder to provide an ugly band 6wrn f ^ connector, and a tungsten (τ) · ΐη, + rm) barrier layer, such as titanium (Ti), on the dielectric layer, Electrical layer and T1N barrier layer. This barrier layer is used to isolate the metal ions: metal ions at the barrier P ^ ?. After depositing the barrier layer, deposit a metal layer on the early layer and overfill the opening. The opening formed before the metal deposition can define the metal wire pattern. After performing a planarization process to remove the metal outside the opening, the desired metal wire can be formed. An example of the above planarization process is chemical mechanical polishing (

Chemical Mechanical Polishing (CMP) cCMP is a device similar to a grinder, in which the grinding disc is equipped with one or more reagents, which are used to smooth the unevenness of the surface of the semiconductor wafer by chemical reaction. When CMP is used in a metal wire process as described above, this process can be regarded as a damascene process. 523864 V. Description of the invention (2) Slurry, referred to as slurry, is mainly formed by chemical conversion. These extremely high hardness' approximately between 0 · 1 ~ 0 · 5 // m. These abrasive microcomputer tables are filtered with a filter to make the wafer lower during polishing. When the table stops working, the polishing liquid kills. 'The particles are contained among the abrasive particles' Such particles can cause large abrasive particles outside the laboratory to flow out. Therefore, the scratches on the surface of the filter are more likely to prevent the grinding fluid from flowing smoothly to the research. In the CMP process, we usually use the chemical additives used. The size distribution of abrasive particles in the slurry is combined by the combination of the chemical solution used by CMP and the abrasive particles. Basically, 'we use abrasive grains' to polish the surface of the wafer. In the traditional CMP process, large particles of abrasive particles in the c μ P slurry are filtered to remove the number of scratches on the surface. However, when the abrasive particles in the CMP machine will sink with time, they will easily aggregate and form large particles. The degree of scratches on the surface of the abrasive micro-abrasive layer is more serious. In addition, it can block the polishing liquid filter, prevent improper use of polishing, and can not effectively reduce the wafer. Scratches on the surface of the wafer are more serious. If it is a grinding table, the wafer may be cracked. 5-3 Objects and Summary of the Invention The object of the present invention is a method of micro scratching. Lies in k 'can remove metal layer surface

According to the above and other purposes, the present invention has a method of micro-scratching, in which the metal layer is removed from the surface of the metal layer.

523864 V. Description of the invention (3) and wherein the barrier layer is formed on a dielectric layer having an opening in a conformal manner. The first polishing slurry is used to grind the metal layer outside the opening through chemical mechanical polishing. The above polishing slurry has a chemical solution and abrasive particles. Next, using a second mechanical polishing method, a second polishing solution is used to remove the barriers outside the opening. At this time, slight traces are formed on the metal layer. Then, a chemical mechanical polishing method is used to buff the surface of the metal layer with the above-mentioned first polishing slurry to remove micro-scratches on the surface of the metal layer. The preferred fine polishing method for the above metal layer is to perform the fine polishing with the first grinding method for about 1 to 30 seconds. Furthermore, the chemical solubility of this abrasive slurry for fine polishing is lower than that of the first abrasive slurry used to remove the metal layer outside the opening. This lower concentration of the chemical solution is intended to be lowered. Another way is to reduce == control. Adjusting the parameters of the mechanical grinding machine to reduce the fine polishing rate. J member particles or advanced chemistry 5-4 scheme is briefly explained: In order to make this hair more obvious and easy to understand, τ is explained as follows. The first figure depicts the structure of Woyu; the above-mentioned and other, specific embodiments of the invention ... convergence, and advantages can be combined with the accompanying drawings to make a detailed example according to the present invention, which is relatively flat and good, A double metal insert 523864 V. Description of the invention (4) The second diagram shows a schematic flow chart of a metal chemical mechanical polishing process according to a preferred embodiment of the present invention; and the third diagram is another preferred embodiment according to the present invention. Schematic diagram of metal chemical mechanical polishing process. The main part of the label description: 102 open π 104 barrier layer 106 metal layer 108 dielectric layer 202 the first grinding step 204 the second grinding step 206 is used to finely polish the metal and dielectric layer grinding step 208 the third grinding step

5-4 Preferred Embodiments

The first figure illustrates a dual metal insert structure according to a preferred embodiment of the present invention. A barrier layer 104 and a metal layer 106 (Ti, A1, or W) are sequentially formed on a dielectric layer 108 of this structure. The barrier layer 104 is conformal to the dielectric layer 108 having the opening 102, and The metal layer 106 overfills the opening 102 of the dielectric layer 108. The second figure shows a schematic flow chart of a metal chemical mechanical grinding process according to a preferred embodiment of the present invention. Please refer to the second picture and the first picture, this gold

Page 7 523864 V. Description of the invention (5) ---- It is a chemical-mechanical polishing process that includes a first grinding step 202 that can remove the opening 丨 〇2 outer metal 外 106, and a removable opening 1〇. 2 outside polishing step 204 of the array layer 104. There are also other single-step grinding processes < to complete the removal of the barrier layer 104 and the metal layer g outside the opening 102 at the same time. In the first grinding step 202, there is a first grinding slurry that can oxidize the metal layer 1 06 outside the opening 102, and at the same time, a mechanical force with a frictional force is applied to remove these oxidized metals. After the oxidized metal is taken out of the field regions, a second slurry can be introduced to remove the barrier layer 104 (for example, the τ i and T i N barrier layers) outside the opening 102. This second step 204 will be continued until some dielectric layer m is ground. There is no metal left on the field. Short-tailed bird

Please continue to refer to the second figure and the first figure. The metal chemical mechanical grinding process includes a buffing step 208, which uses the first coat refining slurry to remove the previously polished metal layer. 6. To remove ^ 入 研 106 — a thin surface layer. This fine polishing step 208 can remove the micro scratches on the gold / platinum layer and the f-side which will cause the yield of the dual metal damascene process to decrease. In fact, the use of this fine polishing step 2 08 can reduce the number of defects on the surface of the 8-inch wafer during the polishing process. The number of defects on the surface 1 106 is reduced from several hundred to less than one hundred. Removal of micro scratches. '~ T However' The above-mentioned fine polishing step 208 will increase the grinding time and 4 wire resistance values, because the effective wiring of the interconnects in the metal layer 106 part ^^ due to the metal sinking phenomenon and the dielectric layer abrasion phenomenon. cut back. Because Bayer will fine-throw step 2G8, it will not take too long.

Page 8 523864 V. Description of the invention (6) About 1 = 30 seconds. In other words, only about 30 seconds is enough to remove the micro scratches, because the depth and opening of these micro scratches are much shallower. < Because the depth of the micro-scratch is not deep, it is about several nanometers, so the first grinding slurry that is diluted or reduces the concentration of the abrasive particles is more careful for the process of the second step, which is used in the fine polishing step. It is preferable that the chemical concentration of the first polishing slurry in 2008 be lower than the chemical solubility of the polishing slurry in the first polishing step 202 to reduce the fine polishing rate of the metal. Alternatively, the first abrasive slurry abrasive particles used in the metal fine polishing step 208 are made smaller than the first abrasive slurry abrasive particles used in the first abrasive removal step. The first abrasive slurry used in the metal fine polishing step preferably has an abrasive particle concentration of about 0-50%, where == 10% is preferred. The above-mentioned methods of reducing the concentration of the chemical solution and reducing the abrasive particles are beneficial to the control of the metal fine polishing step 208. Another method to reduce the rate of fine polishing is to adjust the parameters of the chemical mechanical polishing machine. If both the grinding and fine polishing of the metal layer j 〇 6 are performed using a phase mechanical polishing machine, then we can reduce the fine polishing rate by adjusting the table number of the machine. σ is usually before the metal layer 106 is finely polished, and after the first and second grinding + steps 202, 2ϋ4 are performed, an additional grinding step 2. 6 is used to finely polish the surface of the dielectric layer 108, As shown in the third figure. Third According to a preferred embodiment of the present invention, a kind of metal chemistry; In this schematic flow chart, the additional grinding step uses a second polishing slurry to finely polish the surface of the dielectric layer 108. ’, Although the present invention has been disclosed in a preferred embodiment, such as limiting this month, anyone who is familiar with this technique, has not left;

523864 V. Description of the invention (7) and scope, equivalent changes or modifications may be made. Therefore, the protection scope of the present invention shall be determined by the scope of the attached patent application. For example, the openings of the above-mentioned preferred embodiments are not limited to openings that can only be double metal inlays. Other openings such as vias, contact windows, and other forms of openings can also be used to remove the metal layer proposed by the present invention. The method of surface micro scratches does not depart from the spirit and scope of the present invention.

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Claims (1)

523864 Method for removing micro-brake marks on acoustic surface 'wherein the metal layer is formed on a barrier layer, the barrier layer is formed on and conformally on a dielectric layer having an opening, and wherein the metal The layer overfills the opening, and the method for removing the micro-scratch on the surface of the metal layer includes: using a chemical mechanical grinding method to grind the metal layer outside the opening with a grinding slurry, wherein the grinding slurry has a chemical solution, and There are a plurality of abrasive particles; the barrier layer outside the opening is ground by a chemical mechanical polishing method; and a fine polishing is performed by using a chemical mechanical polishing method and a ferrite layer by using a chemical mechanical polishing method. 2. According to the first drinking method of the scope of the patent application, wherein the fine throwing step is in violation, the time required to remove the micro scratches on the surface of the metal layer is about 1 to 30 seconds. 3. The method according to item 1 of the scope of patent application, in which the micro scratches on the surface of the metal layer described in the detailed polishing of gold are less than the concentration, degree of the chemical solution of the grinding slurry used to grind away the opening.浓 Concentration of the chemical solution of the slurry of the metal layer 4. As described in the patent application No. 1 drinking method, which is used to finely read gold: the removal of micro scratches on the surface of the metal layer is used to grind away the openings, inflammation The metal layer of the layer, the house of the house, and the metal of the external grinding slurry are smaller than the grinding slurry particles of the layer. 5 、 If item 1 of the scope of patent application In the method, the thickness of the abrasive slurry of the _______ layer on the surface of the metal layer to remove the micro-scratch on the surface of the metal layer by using fine polishing is 523864. The scope of the patent application is less than 50%. 6. The method for removing micro scratches on the surface of a metal layer as described in item 5 of the scope of the patent application, wherein the concentration of the abrasive particles used for finely polishing the metal layer is about 10%. 7. The method for removing micro scratches on the surface of a metal layer according to item 1 of the scope of patent application, wherein the metal layer is ground and finely polished by a chemical mechanical polishing machine, and the chemical mechanical polishing machine has A plurality of operating parameters that can adjust the fine polishing rate. 8 · The method for removing micro scratches on the surface of a metal layer as described in item 7 of the scope of patent application, further comprising adjusting the number of operations so that the rate of the fine polishing step is less than that of the metal layer outside the opening. Grinding rate. 9 · The method for removing micro-scratch on the surface of a metal layer as described in item 1 of the scope of patent application, further comprising before the metal layer is finely polished, and before the metal layer and the barrier layer outside the opening After the abrasion, the dielectric layer is subjected to chemical mechanical polishing. 10. A chemical mechanical polishing process suitable for a dual metal damascene process. The dual metal damascene process sequentially forms a conformal barrier layer and a metal sufficient to overfill the opening on a dielectric layer having an opening. Layer, the chemical mechanical polishing process includes: Page 12 523864 Performing a first chemical mechanical polishing step to grind the metal layer outside the opening with a first polishing slurry, wherein the first polishing slurry has a chemical / valley solution and a plurality of abrasive particles; and performing a second chemical mechanical A grinding step to use a second grinding water to remove the barrier layer outside the opening, at which time a plurality of micro-scratches are formed on the metal layer; and a third chemical mechanical grinding step is performed to use the first edge Grind, the table buffs the metal layer to remove the release scratches on the metal layer. 11. The chemical mechanical polishing to produce red 'as described in item 10 of the patent application range, wherein the fine polishing step is performed for about 1 to 30 seconds. 12. The chemical-mechanical polishing process described in item 10 of the scope of the patent application, wherein the concentration of the first polishing slurry chemical solution used for fine polishing is less than the first polishing used to grind the metal layer outside the opening Pulp chemical solution concentration. 13. The chemical-mechanical polishing process described in item 10 of the scope of patent application, wherein the first abrasive slurry abrasive particles used for fine polishing are less than the first abrasive used to grind the metal layer outside the opening. Grind the particles. 14. The chemical mechanical polishing process according to item 10 of the scope of patent application, wherein the concentration of the first abrasive slurry used for fine polishing is about 50% or less. 523864 VI. Patent Application Park 15. The chemical mechanical polishing process described in item 4 of the patent application scope, wherein the concentration of the first abrasive polymer abrasive particles used for fine polishing is about 10%. 16. The chemical-mechanical polishing process as described in item No. 丨 0 of the patent application scope, wherein the metal layer is ground and fine-polished by a chemical-mechanical polishing machine, and the reading chemical-mechanical polishing machine has a plurality of adjustable fine Operating parameters for polishing rate. 〃 7 ′ · As described in the chemical mechanical polishing process described in item 6 of the patent application scope, some operating parameters are opened so that the rate of the fine polishing step is lower than the rate of the metal layer being removed. Page 14