TW402552B - Method for adjusting the polishing time of the chemical mechanical polishing process - Google Patents

Abstract

This invention discloses a method adjusting the polishing time of the chemical mechanical polishing process by using an improved polishing time model and having the minimum deviation by iterative adjustment. The improved polishing time model used in this invention needs to consider the major calculation items that will affect the polishing time such as the non-planar surface and machinery wear-out. Every relevant item is correspondent to a weighted parameter. On the other hand, the method for reaching the minimum deviation by the iterative adjustment disclosed in this invention is to polish at least one wafer and measure its polishing speed in a series of chemical mechanical polishing process of a plurality of wafers with equivalent structures, and then compare the polished result with the expected result. Adjust the weighted parameter of each relevant item in the improved polishing time model of based on the difference of the compared result and obtain the required polishing time for the chemical mechanical polishing process. Then repeatedly proceed the foregoing calculations for the polishing time, the polished wafer, the difference between the actual polishing result and the expected result, and the process for adjusting the weighted parameter of each relevant item to adjust the polishing time and obtains the appropriate weighted parameter for each relevant item, and accomplishes the expected polishing time.

Description

402552 V. Description of invention α) 5-1 Field of invention

The invention relates to a method for adjusting the polishing time of a chemical mechanical polishing process (chemical mechanical, polishing pr0cess), and then changes to the ancient shape of θ from ^. Λ • rrr «ή * Fu⑴ 疋 has a use Change the grinding time model to lighten up — think about it, go to the ground. The method of adjusting the MW to achieve the minimum deviation. (Good formula-2 Background of the invention. The level of electricity required by other leveling procedures has been flat and needs to be supplied. It is different in the process of the process, and it will be affected by the chemical process. The chemical formula is widely sought for the surface of the bottom layer. In the conventional research, the measurement of the grinder has no error in the measurement method, and the mechanical mechanical polishing process can not achieve the flat application in the current semiconducting deep sub-micron device manufacturing. 2. Remove the metal layer or its chemical mechanical polishing process. The grinding time is usually only provided by the semiconductor process in terms of quantity. Calculating the required grinding time will make the actual need to consider the results of different grinding machines. Therefore, semiconductor processing is provided. The degree of frankness in the technology, therefore, in the chemical mechanical polishing process, especially for the high level of stroke, whether it is used to flatten the medium, it provides multiple metallization processes, and the amount of grinding during each grinding process is divided by the grinding rate. And the polishing rate can be determined, not only does not consider the difference between the number of wafer grinding and the predetermined polishing amount When the 'conventional grinding techniques to the desired grinding machine loss

V. Description of the invention (2) The calculation between —__________ is obviously not accurate enough, and will cause damage such as excessive grinding damage to the wafer or insufficient grinding. = Grinding process will appear and lead to the capacity of the chemical mechanical polishing process. Material is missing. It is obvious that with the reduction and polishing of the wafers, as the precision required for the semiconductor process, the aforementioned calculation of the required polishing time is not improved. Therefore, the development of a method that can obtain accurate and serious defects has become a demand in the related fields of chemical mechanical polishing procedures. 5 ~ 3 The purpose and summary of the invention: To provide a method that can calculate the required polishing according to the actual situation of chemical mechanical research. Time provides a method to correct the deviation between the grinding results of the actual grinding period. / Is a method for providing a result of polishing a plurality of the same crystals according to the polishing result of the polished wafer. SUMMARY OF THE INVENTION The present invention is directed to a polishing apparatus and a method for polishing a wafer by using a modified polishing time with small deviations to adjust the CMP process. Another object of the present invention is to improve the results of the subsequent polishing of the wafer by the chemical mechanical polishing process of another objective of the present invention, and to calculate the required polishing time. The model and the method of adjusting the maximum grinding time by feedback are proposed. Page 6 V. Description of the invention (3) The improved grinding time model used in the present invention will be affected by the mechanical wear of the grinding mill, etc. The lack of grinding rate is mainly related to the grinding time, where: U: Only the grinding distance and parameters are considered to measure its influence on the grinding time. Focusing on the method proposed by the present invention to achieve the minimum deviation S by feedback adjustment, a series of chemical mechanical polishing processes of a plurality of wafers of the same structure will grind at least one wafer and measure its polishing rate, and then ς = The grinding result is compared with the expected grinding result, and the weights of the relevant terms in the improved grinding time model are modified according to the gap of the weight I2 to obtain the grinding required for the subsequent chemical mechanical grinding process. It is beneficial to modify the weighting parameters here by referring to a database. ^ #FenYu repeatedly performs the above-mentioned calculation of the required polishing time, polishing wafers, the difference between the weighted polishing results and the expected polishing results, and corrects the results of various related items to adjust the required polishing time. The gap between the grinding results in the first stage is effectively reduced, and then the time f weight parameter of each related term and the grinding that can achieve the expected grinding result are obtained. The 4 formula is briefly explained: Chu uses the improved formula as shown in the present invention. Grinding time model and ° support adjustment to achieve the minimum deviation to adjust the grinding of the CMP process

Page 7 402552 V. Description of the invention (4) Flow diagram of the method of time 5 Detailed description of the invention: The chemical mechanical polishing process is usually used to process a wafer, such as a stone evening wafer ', and there are usually many wafers on the wafer. The existence of semiconductor structures, such as metal oxide semiconductor transistor interconnects or isolation. Generally speaking, a wafer is covered with a specific layer before being polished by a chemical mechanical polishing process, which is used to planarize, thin, or remove the specific layer. The possible types of specific layers include at least metal layers. The possible uses of the dielectric layer include at least =; =: and as an internal dielectric layer 'and the metal layer is usually a copper damascene process. The improved polishing time model proposed by the present invention is an uneven, chemical-mechanical grinding surface. The grinding machine condition σ and other factors will affect the grinding time model of the chemical mechanical grinding process to consider the grinding time model, so as to make up for the habit of ::: the lack of distance and grinding rate, only the improved grinding is considered in the technology. The 'time model' considered are the terms related to unevenness of the surface of a specific layer, Shao Dingmu = a total of five degrees related terms, machine characteristics related terms, polishing pad. The overall thickness and pad activation carrier wear related terms. Damage related items and research

Page 8 4425¾¾._ Five 'Description of the invention (5) The term related to the unevenness of the surface of a specific layer (rough iayer compensation) reflects the actual semiconductor process, no matter which method the specific layer is formed on, the surface exists to a certain degree The fact that the ups and downs are uneven. It is also necessary to take time to remove the unevenness on the surface of these special layers when performing the CMP process. This model expresses this in terms of the ratio of the average undulation of the specific layer surface to the actual polishing rate of the CMP process. A related term. The overall thickness of the special layer and the density-related term (bulk compensation) reflect the grinding time required to remove a specific layer of a predetermined grinding thickness. Similar to conventional techniques, the present invention expresses this related term as the ratio of the average thickness of a particular layer to the actual polishing rate of the chemical mechanical polishing procedure. The terms related to machine characteristics (polish rate variation compensation), pad aging compensation (pad aging compensation), and pad pad activation compensation (pad dresser compensation) reflect the polishing results and the required polishing time. Influence of the machine and consumables used to perform the CMP process. '' Machine characteristics related items reflect the differences between different forms of CMP machines, as well as the differences between different CMP machines of the same form. Because these differences will result in different grinding rates of different chemical mechanical grinding machines and different ways of changing the grinding rate, each chemical machine grinding machine must be individually calibrated to confirm the content of its machine characteristics related items.

ΑΠ2552 ____ 5. Description of the invention (6) " The wear pad related items reflect the impact of the wear of the grinding pad on the grinding process during repeated grinding. The related items of polishing pad activation carrier depletion reflect the influence of the polishing pad carrier depletion on the polishing process during repeated polishing. In this improved grinding time model, "the influence of a related term will change with different chemical mechanical polishing procedures and different chemical mechanical polishing machines, so each related term corresponds to a weight parameter ' In order to reflect the change of its impact, each of the weight parameters is not less than zero and is not greater than "-. After all the grinding time related terms are determined, this model can be expressed as the following equation: The model estimates the grinding time = C F1 X related layer surface unevenness related item + CF2 X specific layer overall thickness and density related item + CF3 X machine characteristics related item + CF 4 X grinding 塾 wear related item + CF5 X polishing pad activation carrier wear related item Among them, CF1, CF2, CF3, CF4, CF5 are weight parameters corresponding to the polishing time. It must be noted that 'Because a series of wafers are usually polished in the same chemical mechanical polishing machine in the manufacturing process, so In the calculation of the polishing time of different wafers, the terms related to the machine characteristics can be fixed: In addition, due to the effect of wear and tear is gradually Change, so the polishing time calculated in different wafers, the polishing pad wear items associated with the activation of the polishing pad wear carriage

Page 10 40S552

5. Description of the invention (7) — = 2: It can also be regarded as fixed. Of course, when the number of terms of this series of wafers cannot be regarded as fixed and its shape must be considered: three: the terms can be expressed by equations, and the detailed chemical mechanical polishing machine and various losses on the chemical mechanical order Influence what is built. Aocheng The present invention proposes a process for adjusting the minimum deviation by feedback adjustment, which is one of the chemical mechanical polishing procedures, and the polishing time is shown in the first figure. On the left, the flow chart is as follows. The first step is to provide a plurality of wafers, as shown in the first block 11. Among them, the predetermined polishing amount of each wafer is the same as that of other wafers. The scheduled research amount is the same, that is to say, the chemical milling process scheduled for each wafer is the same. The difference between the individual wafers is due to the unavoidable random errors in the process of forming each wafer, such as the difference in deposition thickness or the shift of the photoresist position formed by the lithography process. And the surface of each wafer ^ = covered by a specific layer ', and the chemical mechanical polishing process is used to grind the two or two layers, and the content of the specific layer is as described above. Second, as shown in the second box 12, measure the average surface relief of the specific layer covering each wafer surface, and find the surface relief of the specific layer of all wafers. Third, as shown in the third-party block 13, a certain number of wafers are sequentially put into a chemical mechanical polishing machine to perform a chemical mechanical polishing process.

5. Description of the invention (8) = the actual grinding rate. The number of wafers in this chemical two:? Divide: a specific layer with a fixed grinding amount. At this time, j = 疋, and it can also be multiple. The amount of magic four 'is measured and the initial actual grinding amount of each wafer being chemical mechanical; ^ @ & & is recorded. Fifth 'Grinding by the private mechanical grinding private sequence', as shown in the fourth box 14, the actual ground hemp measured by the tap button — β (° actual grinding amount and actual grinding amount and box-grinding time, and will start The modified polishing time model is used, and the five-positive polishing time is determined by using the-★ and ^ tribute library with weight parameters. The database includes a series of corresponding to various wafers, The relationship between various specific layers-research = standing. The thickness of the column, the amount of grinding and the sixth during grinding, as shown in the fifth box 15, and then consider the chemical mechanical polishing process, The number of wafers can also be a plurality of lines. "乂 疋 一" Seventh, compare and record each chemical-mechanical polishing process using this ::, a correction polishing amount of the wafer and one between the predetermined polishing amount Correct the eighth, as in the sixth box 16 *, according to the correction deviation, whether the corrected grinding time obtained in step J is just the amount of grinding required during the process, or the lack of excessive grinding or insufficient grinding. However, 7 = grinding time must be modified The degree, then according to that (Iv) changing the material library further five weight weight parameter correction value to obtain a further correction ^

Page 12 40¾¾¾8 V. Description of the invention (9) Grinding time. Ninth, as shown in the seventh block 17, by performing the eighth step to perform the feedback adjustment to achieve the minimum deviation to the obvious, the chemical mechanical polishing process is repeatedly performed. The deviation between the polishing amount and the predetermined polishing amount is adjusted by 4 rows of feedback adjustment of the polishing time, which is = piece, comparing the actual value. The actual polishing amount of the wafer that can be polished after is adjusted to the scheduled, waiting time, to improve Of course, the chemical grinding process is suitable for grinding. Of course, in order to simplify the operation steps and improve high production efficiency, the difference between the actual grinding amount and the predetermined grinding amount is less than a predetermined volume: I:: Iί The required grinding time is The gap between the gates of the wafers that are subsequently ground is greater than the predetermined gap between the mill and the pre-grinding.-The improved furnace must be used again for this purpose. U: Mechanical grinding process is required. The method of -grinding time: In the program of under-researching with! M, the equation of every-is simulated, and the relationship between them is added up with the adjustment of the linear minimum deviation. Obviously, 'the predetermined grinding amount is to be achieved. To make the first parameter approach zero and the second parameter approach

Ub H One of the great advantages of the present invention is that the present invention uses a page 13 of the fifth, the description of the invention (10) material library as the root to adjust these weight parameters to reduce the backlash needed for the feedback adjustment process, so it can not only effectively The operator of the polishing machine adjusts 2 positive times based on experience only. It reduces the decrease in the chemical mechanical rate and the wear of the wafer. Moreover, the unavoidable effect obtained from time to time corresponds to a particular wafer. The time required when using this method Weighting parameters of related items: predetermined: each grinding LV A of grinding amount, „double follow and grinding time, feedback to this database = as the basis for the grinding time required for future correction of the chemical mechanical grinding process is only as described above The preferred embodiments of the present invention are only intended not to limit the scope of patent application of the present invention; all other equivalent changes or modifications made without departing from the spirit disclosed by the present invention should be included in the scope of patent application described below Inside.

Claims (1)

10¾¾¾¾ 6. Scope of Patent Application • Kinds of use—improved grinding time model and A ==== Research: 仏: The difference between the wafers will be different between Taibaishi and Ira d, and each wafer The random error chemical mechanical polishing procedure on the process is used to grind the specific layer ... cover and read the undulation measurement of an average surface needle of the specific layer covering the surface of the plurality of wafers. ^ 少 " " ^ ^ Sequence of human-chemical mechanical polishing machine, β i ^ tablets were subjected to the chemical mechanical polishing process, and η: an actual polishing rate of the mechanical polishing process was measured at the same time. Here, it is used to remove The specific layer of the predetermined grinding amount;-from r =; ri 1 of the wafer ground by the chemical mechanical grinding program determines a starting time according to the starting actual grinding amount and the actual grinding rate, and sets the starting The difference between the actual grinding amount and the predetermined grinding amount is brought into the improved grinding time model, and the modified equation model is based on the sum of several grinding time related terms to calculate the mechanical grinding process required. The grinding time, the majority Each grinding time phase j uses a plurality of weight parameters to adjust individual proportions, and uses this information to determine a set of starting values for the five weight parameters and a modified grinding time that the chemical mechanical grinding program must perform, 402552 VI. Apply for a patent ® '---- Perform the CMP process on at least one of the wafers; Record · -The correct polishing amount of the said wafer and the predetermined polishing time A correction deviation of the grinding amount; and executing the procedure for achieving a minimum deviation by feedback adjustment, # to determine a set of five weighted correction values based on the two positive deviations, the actual grinding rate, and the database, and The set of correction values is returned to the modified grinding time model to obtain another modified grinding time that must be performed by the chemical mechanical grinding program, and chemical mechanical grinding is performed repeatedly, and the deviation and adjustment between the corrected grinding amount and the predetermined grinding amount are compared The values of the plurality of weighting parameters change a series of feedback adjustment steps of the modified polishing time, so that, subsequently, each polishing of the wafer is polished. Time can gradually come closer to reaching. It is necessary to pre-grind the grinding amount, so that the deviation between the corresponding actual grinding amount and the pre-grinding:!: Can be effectively reduced gradually. The term with a large number of crystals in its method above. 1 piece of crystal sand encompasses Fan Baoli Junior College to apply for a kind of 2. · 3 kinds of :: Γ package item method 'wherein the specific layer of the specific layer of the above mentioned dielectric layer 4. Such as application The method of the first item of the patent, wherein the above-mentioned kind includes at least a metal layer. 5. The method of item 3 of the scope of patent application, of which the above _ page 16 402553-VI. The scope of patent application, way to > includes as a metal interlayer dielectric. 6. As mentioned in the first patent application, its use includes at least the dielectric layer of Fang Zhongmei as the internal dielectric layer. 7. For example, the method of applying for a patent > item q ti · rb L indicates the size d 2 1 item, the above-mentioned method shows that the present invention is not less than zero and neither is greater than one. 8. For example, the method of applying for the first patent in the range of Mo Ribei Gate in M si. The most time-related items of grinding time include-related items of uneven surface of a specific layer. The method of item 8 is described as follows: the wide polishing rate: the individual]]: The average surface fluctuation of the specific layer is related to the actual ^ ^ ^ ^ ^ ^ t -l ^ ^ ^ ^ including the thickness of the special layer and the density item. 11 · If the scope of patent application is $ #, the overall thickness of the Λ layer is densely produced by 10 items, where the specific grinding rate mentioned above: the item is the average thickness of the specific layer and the actual 1 The first grinding time related term in the range includes 1 ^ = method, where most of the above-mentioned machine characteristics related terms. mm Page 17 402552 Page 18