KR20040046208A - method of recycling wafer and apparatus for polishing in thereof - Google Patents

Abstract

PURPOSE: A substrate recycling method and a polishing apparatus applied to the same are provided to be capable of obtaining a recycled substrate having a rounded edge region. CONSTITUTION: A lapping or etching process is carried out on the upper surface of a substrate for removing a thin film containing a failure pattern(S110). A grinding process is carried out on the resultant structure for rounding the sharp tip formed at the edge region of the substrate due to the failure pattern removing process(S140). A polishing process is carried out on the edge region and the upper surface of the substrate for removing the scratches generated at the substrate(S150). Preferably, the thin film is made of one selected from a group consisting of conductive material, dielectric material, and insulation material.

Description

Substrate regeneration method and polishing apparatus applied thereto

The present invention relates to a substrate regeneration method and a polishing apparatus applied thereto, and more particularly, to a substrate regeneration method for polishing a defective substrate generated in a semiconductor manufacturing process to form a regenerated substrate, and to polish the defective substrate. When the polishing apparatus is applied.

In recent years, with the rapid spread of information media such as computers, semiconductor memory devices are also rapidly developing. In terms of its function, as semiconductor memory devices are required to operate at a high speed and have a large storage capacity, semiconductor device manufacturing techniques have been developed to improve the degree of integration, reliability, and response speed of devices. As described above, a method of manufacturing a semiconductor device for improving integration and response speed of a device may be formed by repeatedly performing unit processes such as etching and diffusion after forming an insulating film or a conductive film on a substrate.

As described above, a substrate provided to form a semiconductor device, that is, a wafer made of a semiconductor material such as silicon is required. There are various kinds of wafers. The wafers can be classified into three types, namely, a prime wafer, a test wafer, and a dummy wafer, depending on the purpose. Here, the prime wafer refers to a wafer on which fine patterns are formed to form an actual semiconductor device, and the test wafer refers to a wafer used to monitor a defect or progress of each unit process. In addition, when the dummy wafer is subjected to a batch process, that is, a diffusion process using a furnace or an etching and deposition process using a chamber, the number of prime wafers is larger than the batch size. If less, it refers to the wafer to be used additionally.

In the semiconductor manufacturing process, a defective wafer is generated due to an undesirable result in the pattern and the metallization formed on the prime wafer. The defective wafer thus generated is not transferred to the manufacturing process of the semiconductor device, and analytical specimens of the analysis apparatus are used. Used or discarded. In addition, dummy wafers and test wafers are also discarded after being used once or several times. As a result, disposal of defective wafers has caused a problem of raising the cost of the manufacturing process. For this reason, wafer recycling methods for recycling the defective wafers in an effort to further lower the cost of the wafer in the manufacturing cost of the semiconductor device are disclosed in US Pat. Nos. 5,622,875 (Lawrense) and 5,855,735.

In a conventional regeneration method of a conventional substrate, first, the upper surface of the substrate is wrapped to remove the external material layer in which the defect of the pattern occurs. (S10) Then, the upper surface of the wrapped substrate is etched using an etchant. (S20) Then, the edge region of the substrate and the upper surface of the substrate are polished (S30, S40), and the substrate is cleaned and inspected (S50, S60) to remove particles generated in the polishing process. The defective wafer is formed to be reused in the manufacture of semiconductor devices.

However, since the sharp tip is formed on the surface where the edge region and the upper surface of the substrate meet, the recycled substrate formed as described above generates particles in the edge region having the sharp tip due to thermal stress of the manufacturing process. In addition, the particles thus produced cause defects in the manufacturing process of the semiconductor device, resulting in a decrease in yield of the semiconductor device and an increase in manufacturing cost.

Accordingly, a first object of the present invention is to provide a method for forming a recycled substrate having rounded edge regions of a substrate in a process for recycling a defective substrate.

It is a second object of the present invention to provide a polishing apparatus which is applied to polish the edge area of a substrate to be rounded in a process for recycling a defective wafer.

1 is a process flow chart for explaining a conventional method for forming a recycled substrate.

2 is a process flowchart illustrating a regeneration method of a substrate according to an embodiment of the present invention.

3A to 3C are cross-sectional views illustrating the shape of a recycled substrate formed by the method shown in FIG.

4 is a view for explaining a polishing apparatus applied to regenerating a substrate according to an embodiment of the present invention.

5 is a view for explaining a polishing apparatus applied to regenerating a substrate according to another embodiment of the present invention.

* Explanation of symbols for main parts of the drawing

50: silicon substrate 60: thin film

100: polishing apparatus 110: cylindrical roller

120: first polishing unit 130: second polishing unit

140a: first polishing pad 140b: second polishing pad

200: support

According to an aspect of the present invention, there is provided a method of removing the thin film including the defective pattern by lapping or etching the upper surface of the substrate on which the thin film including the defective pattern is formed; Grinding the sharp tip formed in the edge region of the substrate as the thin film including the defective pattern is removed; And a method of polishing an edge region of the substrate and an upper surface of the substrate to remove scratches formed on the edge region of the substrate and the upper surface of the substrate.

The present invention for achieving the second object is attached to one side of the plate and a plate for contacting a specific area of the substrate, and polished so that the sharp tip formed in the edge region of the substrate rounded without damaging the substrate The present invention provides a polishing apparatus including a polishing pad including a first polishing portion having a soft material and a second polishing portion having a hard material.

Therefore, the recycled substrate formed by the method of the present invention can be recycled to the starting substrate applied to manufacture the semiconductor device because the particles are not generated when it is subsequently applied to the semiconductor manufacturing process, as well as the substrate to monitor the process of the manufacturing process. Can also be used as Therefore, the manufacturing cost of the semiconductor device can be reduced by recycling the defective substrate in which particles are not generated as described above.

Hereinafter, a regeneration method of a substrate will be described in detail with reference to the accompanying drawings.

2 is a flowchart illustrating a method of regenerating a substrate according to an exemplary embodiment of the present invention, and FIGS. 3A to 3C are cross-sectional views illustrating a shape of a regenerated substrate formed by the method illustrated in FIG. 2.

2 and 3A, first, a silicon substrate 50 having at least one thin film 60 including a defective pattern stacked thereon, and a thin film 60 stacked on a surface of the silicon substrate 50. The substrates are classified according to a type (S100). For example, a substrate on which a silicon oxide film is formed on a surface of a silicon substrate and a substrate on which a silicon nitride film is formed are classified into different kinds of substrates.

Subsequently, a lapping process or a grinding process for removing a portion of the thin film 60 formed on the substrates classified according to the types of thin films may be performed to include the defective pattern as illustrated in FIG. 3B. The thin film 60 is removed (S110). At this time, a sharp tip A is formed in the edge region of the substrate due to the lapping and grinding process.

The lapping and grinding process applied in one embodiment of the present invention is mainly for removing thick films of several tens of micrometers formed on a silicon substrate and in the process of forming a plurality of thin films and fine patterns on the silicon substrate. It is mainly applied when this occurs. However, the lapping and grinding process is a lapping and grinding process because the thickness of the thin film formed on the silicon substrate 50 is only a few μm when a defect occurs in an initial process step to manufacture a unit process or a semiconductor device Can be omitted.

Subsequently, although not shown in FIG. 2, a labeling process for forming an identification symbol for classifying the respective substrates may be further performed in a predetermined region of the substrate on which the lapping process is completed or the classification process according to the thin film, for convenience of the process. Can be. In the labeling process, a method of forming an identification symbol using a laser is widely used.

Subsequently, if the defective pattern and impurities of the remaining material layer are not completely removed after the lapping and grinding process is completed, the etching process is further performed. (S120) The etching process is performed in a single step or a multi-step process. The process uses a method of using an etchant containing at least one alkali or acid of the substrate and a plasma etching method by attack from heavy molecules or ions. Here, the lapping process and the etching process may be selectively performed according to the type of the substrate.

At this time, the etching liquid used in the etching process is determined according to the type of thin film remaining on the substrate surface. For example, when the thin film is a silicon oxide film, it is removed using a hydrofluoric acid (HF) solution or a buffered oxide etchant (BOE), and when the thin film is a silicon nitride film, a phosphoric acid (H ₃ PO ₄ ) solution is removed. To remove. In particular, the etching process preferably removes about 5 to 10 μm thick single crystals from the silicon substrate in the final etching step in order to remove all of the thin films including damage patterns and contamination that are not completely removed by the lapping process.

After the etching process is completed as described above, the operation of checking whether the surface of the silicon substrate 50 is completely exposed is performed. As a method of confirming the exposed state of the surface of the silicon substrate, a method of visually inspecting the surface of the silicon substrate 50 and a method of inspecting whether deionized water remains on the surface of the silicon substrate after dipping the silicon substrate into deionized water and the like There is this. The above principle can be seen from the fact that the deionized water remains on the surface of the silicon substrate because the silicon oxide film or the silicon nitride film is very hydrophilic. In addition, the above-mentioned visual inspection is a method of using a characteristic showing an inherent color according to the thickness of the film layer, which is particularly useful in the case of silicon oxide film.

At this time, as a result of confirming the surface state of the silicon substrate 50 by the above-described method, if the surface of the silicon substrate is not completely exposed, the substrate is classified again according to the type of thin film remaining on the surface of the silicon substrate 50, The etching process and the surface condition checking of the substrate must be performed again.

Subsequently, after the thin film 60 including the defective pattern is removed, the process of grinding the edge region so that the sharp tip formed in the edge region of the silicon substrate 50 is rounded is performed (S140). In order to round the sharp tip A formed at the edge region, the grinding wheel of the grinding machine must be tilted by about 45 to 60 degrees to grind the edge region. If the grinding angle θ of the grinding wheel is less than 45 °, it may cause not only the edge region of the substrate but also the surface of the silicon substrate 50 to cause defects in the silicon substrate. Because it is not.

In addition, instead of the grinding wheel used in the grinding process, it is also possible to apply the polishing apparatus shown in FIGS. 4 and 5 to polish the edge region of the substrate.

The reason for performing the grinding process on the edge region is that the edge region and the upper surface of the silicon substrate 50 meet as the thin film existing on the surface of the silicon substrate 50 is removed by the lapping or etching process. At the sharp tip A is formed. As a result, the silicon substrate 50 having the sharp tip A is subjected to thermal stress during annealing and deposition processes for forming a semiconductor device, and thus the strength of the tip is very weak and many particles are generated in a subsequent process. . In other words, since the semiconductor device may be contaminated to cause a defect of the device, the sharp tip A of the edge region is removed before the silicon substrate is regenerated and reused.

Subsequently, as shown in FIG. 3C, a water-soluble wear containing a colloidal suspension or colloid of an abrasive cloth or an inorganic abrasive material in which a particulate abrasive material is embedded after forming the ground silicon substrate 50b so that a sharp tip is not formed in the edge region. The first polishing process is further performed to finely polish the rough surface (scratch) of the edge region by using the abrasive cloth containing the agent. (S150)

Subsequently, a second polishing process is performed to remove the scratches and the lower region of the substrate, which are present on the surface of the polished silicon substrate 50b. In this case, it is preferable to use a chemical mechanical polishing (CMP) process as the polishing process. The depth of polishing the surface of the silicon substrate 50b may be selectively adjusted according to the type of impurities formed on the surface of the silicon substrate 50b to be polished.

Subsequently, after the polishing process is completed, a cleaning process for removing foreign substances and particles remaining on the surface of the silicon substrate 50b is performed.

The cleaning process consists of a chemical cleaning step using a chemical solution and a physical cleaning step using a brush. Here, the chemical cleaning step includes a first chemical solution containing ammonium hydroxide (NH ₄ OH) solution having excellent ability to remove organic pollutants and a hydrochloric acid (HCl) solution having excellent ability to remove inorganic pollutants. 2 Can be carried out using a chemical solution. The physical cleaning step is a cleaning step for removing particles remaining on the surface of the silicon substrate 50b that has been subjected to the chemical cleaning step. The deionized water is supplied to the surface of the silicon substrate 50b and the front and rear surfaces of the silicon substrate 50b. Clean by scrubbing with different brushes at the same time.

Subsequently, a substrate inspection process for measuring the state and thickness of the silicon substrate 50b in which the cleaning process is completed is performed (S180). When measuring the thickness of the silicon substrate, the degree of deformation of each silicon substrate 50b, for example, the uniformity of the thickness, the degree of warpage, the average thickness, and the like are measured together. In this case, when the thickness and the degree of deformation of the silicon substrate 50b show a value within a desired range, the contamination degree (such as particle number and contamination by metal atoms) of the silicon substrate 50b may be further examined. Therefore, when the contamination degree of the silicon substrate 50b shows a value within a predetermined range by the above inspection, it can be recycled into a test wafer, a dummy wafer or a prime wafer.

4 is a view for explaining a polishing apparatus applied to regenerating a substrate according to an embodiment of the present invention.

As shown in FIG. 4, the first polishing apparatus 100a of the present invention includes a cylindrical roller 110 corresponding to a polishing plate, a first polishing portion 120 of a soft material, and a second polishing portion of a hard material ( And a first polishing pad 140a made of 130. A first polishing pad 140a is attached to a side surface of the cylindrical roller 110 in contact with the substrate, and the first polishing pad 140a is formed of a hard polishing cloth with a second polishing portion 130 and soft material. The first polishing part 120 made of a polishing cloth of a material is laminated. That is, in the first polishing pad 140a, a second polishing portion 130 is positioned at a portion that is in contact with the cylindrical roller 110, and a first polishing portion 120 is positioned at a portion in contact with the substrate. . The first polishing pad 140a having such a structure may be formed by coating a material that may wear the substrate on one side of the polishing cloth having a soft material.

Tilt the first polishing apparatus 100a included in the first polishing pad 140a having the above configuration at an angle of about 45 to 60 ° to polish the edge region of the substrate W placed on the support 200. When the edge region of the substrate having a sharp tip is in contact with the second polishing portion 130 made of a hard polishing cloth can be polished faster, the area is in contact with the first polishing portion 120 made of a soft polishing cloth Are gently polished. As a result, the edge region of the substrate has a rounded shape.

5 is a view for explaining a polishing apparatus applied to regenerating a substrate according to another embodiment of the present invention.

As shown in FIG. 5, the second polishing apparatus 100b of the present invention includes a cylindrical roller 110, a first polishing part 120 made of soft material, and a second polishing part 130 made of hard material. And two polishing pads 140b. The second polishing pad 140b positioned on the side of the cylindrical roller 110 in contact with the substrate W. The first polishing portion 120 made of a soft cloth and the second polishing made of a hard cloth. The portions have a constant size and are arranged repeatedly from each other on the cylindrical roller side. That is, the second polishing pad 140b attached to the side surface of the cylindrical roller 110 may include a first polishing unit 120, a second polishing unit 130, a first polishing unit 120, and a second polishing unit ( 130) is repeatedly arranged in order.

Therefore, the second polishing apparatus 100b including the second polishing pad 140b having the above structure is tilted at an angle of about 45 to 60 ° so that the edge region of the substrate W placed on the support part 200 is opened. When polishing, the edge region of the substrate having a sharp tip is sequentially contacted with the first polishing portion 120 and the second polishing portion 130, thereby making it possible to stably and quickly polish the edge region of the substrate.

According to the present invention, in the process for regenerating the substrate, a sharp tip generated in the edge region of the substrate is removed to form a regenerated substrate having a rounded edge region. The recycled substrate having the edge region rounded thereafter may be used as a wafer for monitoring a process of the semiconductor manufacturing process because particles are not generated in the edge region of the substrate when applied to the semiconductor manufacturing process. Therefore, the defective substrate can be recycled as described above, thereby increasing the yield and manufacturing cost of the semiconductor device.

In addition, when polishing the edge region of the substrate using a polishing member including the hard polishing portion and the soft polishing portion of the present invention, the substrate having the sharp tip formed on the edge region of the substrate is more rounded without damaging the substrate. Can be polished.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (10)

(a) removing the thin film including the defective pattern by lapping or etching the upper surface of the substrate on which the thin film including the defective pattern is formed; (b) grinding the sharp tip formed in the edge region of the substrate to round by removing the thin film including the defective pattern; And (c) polishing an edge region of the substrate and an upper surface of the substrate to remove scratches formed on the edge region of the substrate and the upper surface of the substrate. The method of claim 1, wherein the thin film is formed of at least one material selected from the group consisting of a conductive material, a dielectric material, and an insulating material used in a semiconductor device. The method of claim 1, wherein the grinding and polishing angle of the edge region is 45 to 60 degrees. The method of claim 1, wherein the polishing process comprises using a polishing pad including a first abrasive cloth having a soft material and a second abrasive cloth having a hard material. The method of claim 1, further comprising, after step (c), a cleaning process for removing impurities present in the substrate and an inspection process for inspecting the state of the substrate. A plate for contacting a particular area of the substrate; And It is attached to one side of the plate, and consists of a first polishing portion having a soft material and a second polishing portion having a hard material to polish so that the sharp tip formed in the edge region of the substrate is rounded without damaging the substrate. A polishing apparatus comprising a polishing pad. 7. A polishing apparatus according to claim 6, wherein said specific region is an edge region of a substrate. 7. A polishing apparatus according to claim 6, wherein said plate is a roller having a cylindrical shape. 7. The polishing apparatus according to claim 6, wherein the polishing pad has a structure in which a first polishing portion is stacked on a second polishing portion in contact with a plate. 7. The polishing apparatus according to claim 6, wherein the polishing pad has a structure in which the first polishing portion and the second polishing portion are interviewed on the upper surface of the plate and are repeatedly arranged with each other.