TW460961B - A method of processing semiconductor wafers - Google Patents

Abstract

A method of processing a semiconductor wafer sliced from a single-crystal ingot and having front and back surfaces and a peripheral edge. The method includes the steps of grinding the wafer to improve the thickness uniformity of the wafer and to reduce waviness in the wafer, etching the wafer to reduce stress in the wafer and smooth the surfaces, and performing plasma assisted chemical etching (PACE) on the wafer to improve the thickness uniformity of the wafer.

Description

Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 460961 A7 ------B7__ V. Description of the Invention (1) 'Background of the Invention The present invention is generally related to a process flow for processing semiconductor wafers, and more specifically That said, it's about a process flow that uses a combination of polishing, etching, and galvanic chemical etching (PACE). Semiconductor wafers, which are the starting materials for the fabrication of integrated circuits, must meet certain flat surface requirements. Such wafers must be particularly polished to flatten them with circuits (or layers deposited on them), such as by electron beam imaging or lithography. Wafer flatness in the focus of an electron beam plotter or optical printer is important for consistent imaging in electron beam imaging and lithography. The flatness of the wafer surface directly affects the line width capability of components, process range, yield and yield. Continued reductions in component sizes and increasingly stringent component manufacturing specifications have forced semiconductor wafer manufacturers to produce flatter wafers. The flatness of the wafer can be a flatness variation parameter for the whole area (for example, " gbir ") or a flatness variation parameter for a local place (for example, 'location total indication reading, location optimum reference plane (" SFQR ") or location general indication The reading is characterised by turning it back towards the central focus of the test (" SBIR ")). A more detailed discussion of wafer planarization can be found in F. Shimura's Semiconductor Silicon Crystal Technology (Academic Press 1989), page 191.195. GBIR is often used to measure the flatness of the whole area, which is the difference between the maximum and minimum thickness of the wafer. The GBIR of a wafer is an important indicator of wafer polishing quality. SB IR is often used to measure the flatness of local locations. It is the sum of the maximum positive and negative deviations between the surface and a reference plane in a small area of the wafer. This paper size applies the Chinese National Standard (CNS) A4 specification (21〇χ). 297 mm) ------------- -------- Order --------- Line C (Please read the notes on the back before filling this page) Printed by the Intellectual Property Bureau's Consumer Cooperatives of the Ministry of Economic Affairs 4 6 096 V. Description of the invention (2 Parallel to the back surface of the wafer and in the center of the local place-= face crying. SFQR, which is becoming more widely used The measurement of local support is the sum of the maximum positive and negative deviations of the surface in a small area of the wafer with reference to the reference plane. Semiconductor wafers are generally prepared from single-crystal ingots, such as a silicon strip, which : Trimming and grinding to obtain—or multiple planes—for orientation of the wafer in subsequent processes. The ingot is then cut into individual wafers, each of which = passes through many processing operations to make the wafer Flat, removes damage and reflects the surface at Γ 7. Generally, the periphery of each wafer is made round to reduce Risk of wafer damage during further processing. In traditional process flow, each wafer is then laPPed to improve thickness-consistency, reduce cutting damage and reduce undulations in the wafer. Before the polishing and cleaning process, the wafer is etched to smooth the surface, and preliminary polishing is used to polish and flatten the surface. This traditional process flow is limited by wafer flatness, and thus limited by the yield of acceptable inking. Part of the problem is that the preliminary polishing operation is generally inaccurate in flattening the wafer. The traditional preliminary polished wafer ideally has an SBIR of about 0.4 microns for any 20 mm X 20 mm local spot and for any 25 mm X SFQR of about 0.18 microns at a 32 mm local site (as disclosed in the National Technology Roadmap for Semiconductors: Technology Needs published by the Semiconductor Industry Association). However, This is dependent on the actual process conditions and is often significantly larger than 0.4 microns. In fact 'wafers traditionally processed Only a small percentage of the size of the crystalline paper is applicable to the Chinese National Standard (CNS) A4 (21 × 297 mm) -------- ^ --------- (Please read the back first (Notes on this page, please fill out this page) 46 0961 A7

The circle meets the above-mentioned ideal flat specifications. Wafers that do not meet this specification are usually ‘=, and discarded,’ which has some disadvantages in grinding and preliminary polishing operations, which increase the cost of processing semiconductor wafers. Traditional grinding machines are not automatic 'which increases the labor and time required for operation. Polishing is a slow heartbeat and requires relative | time to remove material from the wafer. Therefore, more polishing machines are needed to increase the total amount or yield of wafers. In addition, expensive consumables are used in each grinding and preliminary polishing operation (eg table materials, pads). Therefore, there is a need for a new program flow that is sufficient to improve the flatness of semiconductor wafers, the goodness of production operations and the cost efficiency of the program flow. The invention is summarized in the goals and characteristics of this month. It can be noted that the method of providing-processing semiconductor wafers-which manufactures completed wafers with flat surfaces, and · provides such a method that does not require polishing; Provide such a method that does not require preliminary polishing, provide such a method to reduce wafer undulation; provide such a method to produce more consistent full-area and local-thickness wafers; and provide such a method that is economical for use on processed wafers method. w Generally speaking, a method for processing a semiconductor wafer. The wafer is cut from a single TO ingot and has front and back surfaces and a circular periphery. It includes a step of polishing the oval to improve the thickness consistency of the wafer and Reducing the undulation of the wafer, theta circles to reduce the stress in the wafer and smooth the surface, and to perform a PACE on the wafer to flatten the wafer and improve the thickness consistency of the wafer. As far as another aspect of the invention is concerned, the method includes the step-by-step rate of polishing the wafer (please read the precautions on the back before filling out this page)-line. ... _-6 paper rule Choi n IH4 6 096 1

The Intellectual Property Office of the Ministry of Economic Affairs and Consumer Affairs Co., Ltd. printed M 骡 to improve wafer thickness consistency and reduce wafer undulations. Use-high gloss nicking agent to micro-move the wafer to remove a total thickness of less than about 15 microns, so that the stress in the wafer is reduced and the front and back surfaces of the wafer are thus smoothed. The method also includes performing electropolymerization on the wafer to promote chemical engraving (PACE) to flatten the wafer and improve wafer thickness-consistency. The front surface of the wafer is finally polished. Wafer processing does not require any preliminary polishing steps and no grinding steps. Other objects and features of the present invention are partially obvious, and some will be pointed out below. The schematic diagram is a schematic diagram showing the Tjt method for manufacturing a wafer according to the present invention. 0 Detailed description of the preferred embodiment. For the preferred method of the present invention, simultaneous dual surface polishing (SDSG) is used. The combination of etch, plasma, and plasma facilitates chemical etching steps to fabricate semiconductor wafers. This method produces relatively flat wafers with relatively uniform thickness penetration and low undulation 'without the need for preliminary polishing or grinding operations. The semiconductor wafer is cut from a single crystal bond, for example by using a conventional inner diameter recording or a conventional wire recording 'to have a predetermined initial thickness. Cut: The wafer is generally dish-shaped and has a round perimeter and back-to-back front and back surfaces. For the purposes of this description, the front surface of the wafer is the last surface of the component. The initial thickness of each wafer is substantially larger than required to allow subsequent processing operations to reduce the thickness of the wafer without risk of damaging the wafer. For example, the initial thickness may be in Xiao _-Li (please read the precautions on the back before filling this page) -------- Order ---------- Line. -7- This paper ruler Qian Duanguan 46 096 Α7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 5. Description of the invention (in the range of micrometers. After dicing, the wafer undergoes a cleaning procedure to remove any deposits on the wafer from the dicing operation. Particles. The round periphery of the wafer is contoured (rounded) with a conventional edge polisher (not shown) to reduce the risk of damage to the wafer during further processing. Clean the wafer again to remove edges from the edge Polishing operation = particles deposited on the wafer. The wafer can be laser-printed before the next operation. Tian Dingzhi's wafer undergoes a polishing operation to polish one or both of the front and back surfaces to improve the wafer. Consistent thickness and reduce damage and undulation caused by the cutting operation. The polishing operation is preferably a simultaneous double surface polishing (SDSG) operation. However, other polishing operations are also within the scope of the present invention, including But not limited to traditional single surface or non-simultaneous dual Light operation, or a multi-step polishing process, which includes preliminary, intermediate, and / or micro-polishing steps. In brief, more suitable SDSG operations include placing several wafers in a traditional SDSG instrument. Suitable instruments include Located at 2_34, Minami

Koyo Machine Industries of Uematsu-Cho, Ya〇-City, Osaka, Japan

Model DXSG300 manufactured by Co., Ltd. (Koyo machine) and model MPG_300 manufactured by Nippei Toyama Corp. (NTC machine) located at M5, Shinmei-Cho, Yokosuka-City, Kanagawa. Each wafer is placed between the grinding wheels in opposite positions, with one of the wafer surfaces against a grinding wheel. During operation, one of the wheels moves inward towards the wafer while the two grinding wheels and wafer are rotating. SDSG operations can include a preliminary, intermediate and final polishing step. Generally speaking, the inner grinding wheel is moved in at a rate of about 0.01 to 0.45 cm / minute, depending on the polishing as " preliminary ", " middle " or " final " polishing. Applicable to China Paper Standard (CNS) A4 (210 X 297 mm) for this paper size -------------- ^ -------- tr ------- --❿ -------- 1_______________ (Please read the notes on the back before filling this page)

460961 V. Description of Invention (6)

Koyo machine & 'The preliminary polishing step is best treated at an internal movement rate of about 0.15 to 0.45 chum / minute', about 0.3 cm / minute is more suitable, the intermediate step is at a rate of about 0.06 to 0.18 cm / minute, About 012 cm / min is more suitable 'and the final step is at a rate of about 03 to 009 cm / min, more preferably about 0.06 cm / min. For NTC machines, the preliminary polishing step is preferably processed at an internal movement rate of about 0.03 to 0.09 cm / minute, more preferably about 0.06 cm / minute, and the intermediate step is about 0.25 to 0.08 A rate of cm / min, about 0.05 cm / min is more suitable, and a final step at a rate of about 0.01 to 0.03 cm / min, about 0.02 complex meters / min is more suitable. For K〇〇〇 machine, it is best to rotate the grinding wheel at about 1200 to 3600 revolutions per minute (rpm), more suitable at a rate of about 2200 to 2600 rpm, more suitable at a rate of about 2380 rpm, but the result is Edge speed of about 1495 meters / minute. Furthermore, in a K0y0 machine, the crystal circle is preferably rotated at about 10-30 rpm, more preferably at about 15.25 rpm, and more preferably at about 2 UPm. For NTC machines, the grinding wheel is preferably rotated at about 2000 to 4000 revolutions per minute (rpm), more preferably at a rate of about 28,000 to 32,000 rpm 'and more preferably at a rate of about 2995 to 3,000 rpm. Suitable but 'results in an edge speed of about 1412 m / min. In the NTC machine, the wafer is preferably rotated at about 10-30 rpm, more preferably at about 18-22 rpm 'and more suitable at about 20 rpm. The grinding wheel preferably has abrasive particles in the range of 2 μm, and about 4 μm is more suitable. The sdsg operation removes the thickness of the wafer material in advance, preferably a total wafer thickness of about 10-90 microns is more suitable for a total thickness of about 30-75 microns, and a total thickness of about 60 microns is more suitable. The wafer produced by this polishing process preferably has a 1-mm paper-sized paper towel® National County (CNS) A4 specification (21Q χ as the public)-^ -------- Order- ------- line-ί V {Please read the notes on the back before filling this page) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economy ^ 460961 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economy A7 V. Invention Explanation (7)-X i varies with the area's approximate root square root surface roughness, RMs. The polishing process removes damage in the wafer caused by the cutting process. The polishing process also reduces wafer undulations. The SDSG machine discussed above is also relatively fast in processing wafers. Koy. The machine is capable of processing 4 (300) wafers per hour, while the NTC machine is capable of processing 20; 300 mm wafers per hour. As those who are familiar with this technique can clearly see, the wheel calibration of 3 dirty machines must be carefully monitored and controlled, so that the wafer surface can be evenly polished. If necessary, the wafers can be cleaned on a conventional cleaning station after the polishing process. The wafer then undergoes an etching operation. The etching operation is expected to be any conventional etching operation known in the art. However, the etching operation is preferably a high-gloss etching operation in which the wafer surface is etched with an aqueous solution containing hydrofluoric acid (HF) and an oxidant 'which consistently produces a wafer surface with improved gloss and smoothness. The engraving operation also reduces the stress in the wafer and removes some of the damage caused by the cutting and polishing operations.The etching operation is best to remove from each surface an abrasive equivalent to the grinding wheel or wheel used on each wafer surface. Amount of grain size. A more suitable etching operation is described in DG Schimmel, J. ELECTROCHEM · .SOCIETY, Solid State Science and Technology, Vol. 123, no. 5 pages 734-741 (1976), and a more suitable etching operation Operation is described in a co-assigned application, which is filed today by the following inventors: Henry F. Erk and Anca Stefanescu 0 Co-assigned applications are included herein by reference. In this preferred micro-etching operation, the total wafer thickness is reduced by about 2-20 microns, more preferably about 6-14 microns, and about 10 microns is more appropriate. The size of the paper produced by the etching process is in accordance with China National Standard (CNS) A4 (210 X 297 mm)

Printed by the Intellectual Property Bureau of the Ministry of Economic Affairs on consumer cooperation ^ 6 0; 9 01 A7 ------- B7 V. Description of the invention (8) The circle should preferably have a roughness comparable to that of polished wafers. In general, suitable oxidants for etching the red sequence are based on silicon and iron; more specifically, suitable oxidants include those capable of forming permanganese, ions (MnCV), and chromate ions (Cr〇42-) in aqueous solution. , And dichromate ions (Cr204), and chromium dioxide (Cr03) and mixtures formed therefrom. An oxidant capable of forming permanganate ions in an aqueous solution, such as potassium permanganate (KMn〇4) or sodium permanganate (NaMn〇4) is preferred, in part because of its lower risk. Water etching; each liquid typically contains between about 10 and about 49 weight percent hydrofluoric acid, and between about 0.2 and about 6 weight percent oxidizing agent. The aqueous solution preferably contains between about 30 and about 40 weight percent hydrofluoric acid, and between about 1 and about 2 weight percent oxidizing agent. However, the 'aqueous solution' contains most preferably between about 30 and about 35 weight percent hydroic acid and between about 1 and about 1.5 weight percent oxidizing agent. In the preferred embodiment, the ' aqueous solution comprises about 33 weight percent hydrogen acid and about 1 weight percent potassium permanganate. Generally, hydrofluoric acid and an oxidizing agent are dissolved in water forming an HF aqueous solution and an oxidizing aqueous solution, and the solutions are then mixed together to produce an etching solution having a desired component. For example, a typical aqueous HF solution will consist essentially of water and about 49 weight percent hydrofluoric acid. The oxidant, like a 1N aqueous solution, is usually added to the etching solution. The two aqueous solutions are then mixed to form an etching solution, wherein the weight ratio of the oxidizing agent to hydrofluoric acid is from about 0.01 to about 0.1. The weight ratio of oxidant to hydrofluoric acid is preferably from about 003 to about 0.05. The ratio of the oxidant to the hydrogen decanoic acid determines the etching rate of the solution, which is eroded. 11- This paper size applies the Chinese National Standard (CNS) A4 specification (21 × x297 mm) ------------ -:, k --------- Order --------- line (Please read the notes on the back before filling in this page.) 460961 Printed by A7, Consumer Cooperatives, Intellectual Property Bureau, Ministry of Economic Affairs -------- B7_____ V. Description of the invention (9) The gloss and roughness of the engraved wafer. However, it should be understood that the concentrations of hydrofluoric acid and oxidant in the etching aqueous solution may be different from those described herein without departing from the scope of the present invention. Referring now to equations (1) and (2), the etching procedure is further explained, in which potassium permanganate is used as the oxidant. There is no need to use any special theory. It is generally considered that the oxidation of Shi Xiyue on the surface of the wafer is carried out with KMnO4, or rather a short acid ion (MnO4). Formation of SiO2. Silicon dioxide was then dissolved with hydrofluoric acid (HF). 12HF + 4KMn04 + 5Si < = > 5Si02 + 4MnF2 + 6H20 + 4KF ⑴ Si02 + 6HF = & H2SiF6 + 2H20 ⑺ The etchant solution can be used to etch the wafer surface in many different techniques commonly used in many technologies. For example, one technique, called spin etching, is disclosed in U.S. Patent No. 4,903,717. Rotary etch technology involves rotating a wafer while a continuous etchant is applied over the wafer. The other technique is spray etching, where a continuous etchant spray is applied to the wafer surface. However, it is preferred that the wafer is completely immersed in the etchant solution bath. Although one wafer can be immersed in the solution at a time, it is best to collect some wafers (eg 25 or more) in a box or wafer carrier while immersed in the solution. However, when using such a carrier, certain parts of each fixed wafer will be in constant contact with the carrier, resulting in inconsistent etching processes across the surface of each wafer. To eliminate this problem and provide more consistent results across the entire wafer surface, when immersed in a money etch solution, --------------------- Order ---------- Line C (Please read the notes on the back before filling this page) -12 · 460961 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 _________B7_____ V. Description of Invention (10) Best Rotate the wafer. In addition, 'Because the wafers are tightly spaced', the distance between the wafers is generally between about 4 mm and about 7 mm, and the rotation of the wafer tends to produce a liquid solidified body rotation between the wafers. As a result, blocking of the etchant solution between the wafers generally occurs. Blocking is important because the acid contact of the sand is thought to be related, at least in part, to the mass conversion impedance on the chip-etchant interface. When the etching reaction proceeds, the concentration of the acid and the oxidant decreases on the interface, and the concentration of the reaction product increases. As a result, inconsistent etching results may be obtained not only across the surface of a given wafer, but also from the surface of a wafer to the next one in a wafer set of wafer carriers. To produce a uniformly etched wafer ' and ensure consistent results from one set of wafers to the next, the etchant solution is preferably continuously mixed or agitated throughout the time of the etching process. Agitation or mixing of the etching bath can be achieved by means known in the art, such as using supersonic agitation, agitation devices and recording pumps. However, agitation is best done by passing in or " bubbles " a gas through the etchant solution. (See, for example, US Patent No. 5,340,437). In general, any gas that does not interact with the wafer surface can be used, including elemental gases (such as hydrogen, nitrogen, oxygen), inert gases (such as helium or argon), or compound gases (such as carbon dioxide). It should be noted that in addition to the gas agitation: gas bubbles introduced into the etchant solution, gas bubbles may also be formed by the etching reaction itself. More specifically, when the etchant of this procedure reacts with the wafer surface, hydrogen gas is released, and hydrogen bubbles are generated in the etching bath. These bubbles tend to stick to the surface of the wafer, and Wei may hinder the action of the etchant, resulting in inconsistent etching and possible L _____- 13- This paper rule Money Standard Account Standard (CNS) A4 size x 297 ^) Read the notes on the back and fill in this page) ^ -------- t -------- line / 460961 A7 B7 V. Description of the invention (U) Causes surface pollution. The effects of bubbles, mass conversion impedance, and kinematic impedance on the surface of a wafer etched by an isotropic etching process have been theoretically and experimentally explained by Kulkarni, MS, and HF Erk at the 1997 annual AlChE conference in Los Angeles, And "Wet Etching of Silicon Wafers: Transport and

Kinetic Effects) kulkarni, M_S. And H.F.Erk, Paper 124f, AlChE

Conference, Los Angeles (1997), which is incorporated herein by reference.

Kulkarni and Erk developed a theoretical relationship between bubbles, mass conversion impedances, and motion impedances known as " bubble masks ". They also show theoretically and experimentally that the effects of bubbles (bubble masking) and polishing efficiency of isotropic etching procedures can be increased or decreased by changing the dynamic impedance or mass conversion impedance, or both. Basically, the density of the bubble mask is just a function of these impedances. The impedance is also a function of many variables, such as program parameters and etch mix components. The effect of inverse bubbles can be minimized by adding a surfactant to the etchant solution. Without using any special theory, it is generally believed that the surfactant acts as a wetting agent, reducing the surface tension of the aqueous solution on the wafer surface, and thus preventing the bubbles from adhering to the surface. In addition, it is believed that the surfactant stabilizes the size of the bubbles in the groove, which also helps to produce a smoother and more consistent surface, and therefore provides more consistent etching results. Any surfactant that is stable when an oxidant is present can be added to the etching solution. For example, a fluorinated potassium etchant solution can be added to the etchant solution. It is sold under the commercial name FC-129 (commercially available from 3M Limited ( (Please read the precautions on the back before filling this page), -------- Order ----- Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Online Economy

.6 0961 A7------B7 V. Description of Invention (l2) Company; St. Paul, MN), or sodium dodecyl suifate. However, 'the latest experience suggests that if a fluorinated surfactant is added to the solution', such as potassium perfluoroalkyl sulfonate (sold under the commercial names FC-93 and FC-95, respectively; commercially available from 3M Corporation; st Paul , MN), to obtain a smoother, more uniformly etched surface. When ready to be added to the etchant solution, the surfactant will generally be used in an amount sufficient to prevent air bubbles from adhering to the wafer surface. As explained further in the examples below, wafers can be analyzed in a way that allows for noticeable traces left by bubbles attached to the wafer surface. Generally speaking, the water etch solution contains about 0.05 to about 1 weight percent of a surfactant. The etching solution preferably contains from about 0.1 to about 0.5 weight percent surfactant, or from about 0 to about 0.25 weight percent surfactant. In a preferred embodiment, the water etching solution contains about 0.2 weight percent of a sulfoalkyl surfactant. However, it should be understood that the surfactant concentration in the present water etching solution may differ from that described herein without departing from the scope of the present invention. As mentioned earlier, the limitation of etchant solutions known to date using the oxidant in question is limited to the inability to regenerate or rebuild these solutions. The introduction of other reagents resulted in an increase in salts in the etch bath. The increase in solids in the etch bath can hinder the etch process. This obstacle may be caused by the salt deposited on the wafer surface, which acts as a mask and leads to inconsistent results. Salts can work to reduce the oxidizing power of the reagent. Without using any special theory, the latest experience suggests that the etchant can be regenerated or rebuilt, by restoring the oxidation state of the reagent, or more specifically negative ___ -15- This paper size applies to China National Standard (CNS) A4 Specification (X 297 male cage) (Please read the precautions on the back before filling out this page.) Order-Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs (3) ⑷ (5) Printed by the Employees’ Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs System 460961 A7 ________ B7 V. Description of the Invention (13) Responsible as part of the etching process to oxidize ions on the surface of the silicon wafer. For example, 'especially' refers to an etchant using permanganic acid. Note that a newly prepared etchant solution is generally transparent and has a dark purple color. This purple color is believed to be due to the presence of permanganate ions in the solution. Over time, and as the number of wafers etched in the solution increases, the color of this solution changes, generally becoming purple / brown. It is believed that this change in color reflects the deterioration of the etchant solution due to the consumption of permanganate ions in the solution. Consumption of peresteric acid ions in the solution, and thus the etchant degradation, are generally considered to be due to three potential causes. First, as described above, the etch reaction 11 damages the silicon dioxide by oxidizing the silicon on the surface of the wafer with a reagent that uses a Wei acid, or more specifically, a permanganese hafnium ion (MnO4). The formation of the dioxide dream can be illustrated by equations (3), (4) and (5), as follows:

6H + + 4Mn04 '+ 5Si 5Si02 + 4Mn2 ++ 60H

Mn7 + —Mn2 +

Si0—Si4 + As can be seen from these equations, during the oxidation of silicon on the wafer surface, the oxidation state of solute manganese decreases from +7 to +2 and the oxidation state of silicon increases from 0 to +4. When the etching reaction proceeds, the decrease in the concentration of Mn7 + ions in the tank 'results in a decrease in the oxidation / etching ability of the tank. However, the oxidation state of manganese generally decreases directly from +7 to +2, and a part of manganese may optionally decrease from +7 to +4. The manganese in the +4 oxidation state in the etching solution is considered to be prone to the formation of dioxide. Now refer to the equations (6), (7), (8), etching procedure-16-This paper size is applicable to China National Standard (CNS) A4 (210 X 297) (please read the precautions on the back before filling in this Page) Order --------- line-460961

V. Description of the invention (The formation of manganese dioxide in I4 can be explained as follows: 4KMn04 + 3Si + 4HFzz ^ Q; n ~~ 3Si02 + 4Mn02 + 2H20 + 4KF Mn7 +-^ Mn4 + Si °-> Si4 + ⑹⑺ (δ) Wisdom of the Ministry of Economy The formation of manganese dioxide printed by the Property Cooperative Consumer Cooperative-generally believed to reduce the etching bath because it can precipitate from the solution and prevent manganese from further advancing silicon oxide. In addition, the precipitated dimerization can be deposited on the wafer On the surface, it is allowed to be affected by # * and the surface is not affected by the etch reaction. The second etchant is degraded by A π m, which is due to the strong ionization ability of water. M is a water knife that slowly converts manganese. The acid ion (Μη〇4 ·) decomposes ~ ΜηΟ 'and 02 · ions, or becomes yells. This phenomenon often occurs in dilute acid solutions, such as the liniment solution in question. Finally, the third etch The potential cause of agent degradation is thought to be the tension exerted by the water molecules on the recording ions. This tension is generally thought to cause the solution of these ions. In dilute solutions' these are, for example, permanganese ions in the etchant solution in question. Is hydrolyzed and decomposed into manganese hydroxide Colloidal solution and free oxygen. This reaction occurs under all conditions, but exposure to UV and UV light has been reported to dramatically increase the hydrolysis rate. According to the etching procedure, the etchant solution can restore the oxidizing ability of the agent in the solution To regenerate or rebuild. For example, use permanganic acid etchant to rebuild the degraded (ie reduced oxidation state) oxidation state of manganese to +7 oxidation state to rebuild 'which in turn causes peracid. Ions (Μη〇4 ·) Therefore, the addition of new agents can be avoided, and the related salt oxygen components can also be avoided (please read the precautions on the back before filling this page). -17. This paper size applies China National Standard (CNS) A4 specification (210 X 297 mm) 460961 A7 B7 V. Description of invention (I5 Unwanted increase of pollutants. Generally, §, the etching solution can be contacted with the used or reduced oxidant or dissolved Any agent capable of returning the oxidized state of the solute to its original size for reconstruction or regeneration. For example, an agent that has been used in theory can simply be obtained by contacting the etching solution with oxygen To re-oxidize. However, the used agent and therefore the etching solution itself, in one embodiment of the present invention, it is best to rebuild by contacting the etchant solution with ozone. Generally, 5, ozone introduced into the solution The amount is greater than the metered amount of the used oxidant or solute proton; that is, the reconstruction of the etchant solution is by adding more oxygen or ozone than the stoichiometric equivalent of the used agent or solute. This is achieved in solution. In fact, it is best to add about twice the stoichiometric amount of I or more to the etchant solution. However, it should be noted that if the etchant solution contains other compounds or may be oxidized by the added agent The reagent may need to be larger in size to add the agent used to regenerate the used oxidant. As an example of the foregoing, in order to increase the oxidation state of dissolution, generally more than 0.9 g of ozone per gram of manganese is added to the etchant solution. However, it is preferred to add ozone in an amount of about 2 grams, more preferably about 2.5 grams to about 10 grams of ozone. In this regard, it should be noted that the oxidation of Mn2 + to Mn7 + can be detected visually, because this oxidation causes the re-formation of Mη04 ·, which causes the color of the grooves to change from purple-brown. It should also be noted that if an insufficient amount of ozone is added to the solution, the dissolved Mn2 + ions may oxidize to an oxidation state less than Mn7 +. These lower manganese oxide ions may eventually hydrolyze and form manganese dioxide ' which will precipitate from the solution. In addition, if the ozone-deficient object-18-This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) (Please read the precautions on the back before filling this page) ---- Order- ------ Line: Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 460961 A7

Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 5. Description of the Invention (I6) For example, nitrous acid or sulfide appears in the etchant solution, and additional ozone may be required. The etchant can be exposed to ozone in one of several ways, using methods known in the art, including: 1) direct incidence of gaseous ozone into the etching bath, similar to nitrogen injection 'or 2) to use a packed tower or hollow Chemical fiber gas liquid contactors (commercially available from Hoechst Ceianese and WL Gore & Associates). If reconstruction ozone is also used to agitate the etching bath, the first method is better. However, the second method is better if the bubble effect due to the gas incident may cause additional foam, which is not conducive to the etching process. It should be noted that a chemical oscillator may be added (refer to, for example, "Design of a Permanganate Chemical Oscillator with Hydrogen Peroxide" by A. Nagy, j. Phys Chem., Vol. 93, page 2807-28 (1989)) Into the etchant solution, it is used as a device to prevent the formation of dioxins and deposits. Without using any special theory, it is generally believed that chemical oscillating agents can complex or bond to colloidal manganese dioxide to prevent its precipitation, thus allowing the oxidation state of all manganese to be maintained in solution. Such an agent can be used in combination with, for example, ozone to further extend the life of the etchant solution. Another method of using the chemical Zhenbaozi is to add phosphonic acid (H3P04) to the solution of the last name. More specifically, phosphoric acid may be added to the solution to prevent the precipitation of manganese dioxide in a manner very similar to the chemical oscillator described above. Therefore, an amount sufficient to recombine with the violent dioxide formed and maintained in the solution is added. More specifically, the etchant originally prepared will contain from about 1 to about 10 weight percent phosphoric acid. However, the amount of phosphonic acid added is preferably about 1 to about 5-19.-This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) ----------- ---------- Order --------- line ^^ (Please read the notes on the back before filling this page) 460961 (9) (10) (11) (12) A7 B7 V. Description of the Invention (Π) Weight Percentage "—Phosphoric acid is added to the etchant like an aqueous solution, such as an 85 weight percent H3P04 solution. As another embodiment of the reconstituted oxidizing agent of the present invention, high sulfuric acid and acid salts are considered to be added to the etchant solution. It is not necessary to use any special theory of the regeneration machine using an etchant solution of permanganic acid] e j teeth are expressed by the formulas (9) to (12) as follows. K2S2O8 + H2SO4— · H2S2O8 + K2SO4 4H2〇 + 3H2S208 + 2Mn02— 2HMn04 + 6H2S04 (S27 + 08) 2-^ 2 (S6 + 04) 2 · (Mn4 + 02)-> (Mn7 + 04) · Reference In Equation (9), potassium persulfate and sulfate react to form peroxosulfuric acid and potassium sulfate. In equation (10), peroxysulfuric acid oxidizes manganese dioxide to form hydrogen permanganate and sulfate. Caused by oxidation of Mn2 + to Mn7—

The re-formation of MnO4 can be seen by the color change from purple-brown to purple in the tank. Considering the above, potassium sulfate and sulfur are generally added with about equal gram molecular weight. In addition, each of these compounds is generally added at a molar ratio of about 1: 1 to about 5: 1, relative to the amount of manganese dioxide in the solution. Therefore, in order to fully reconstruct the permanganate-based etchant, about 3 to about 10 weight percent of potassium persulfate and about 1 to about 5 weight percent of sulfuric acid are added to the tank. However, it is preferred to add about 3 to about 5 weight percent potassium persulfate and about 1 to about 3 weight percent sulfuric acid. Potassium persulfate is generally in the form of powder. • 20- & Paper Standard (CNS) A4 -------- P! _Γ4 -------- Order -------- -Line, (Please read the precautions on the back before filling out this page) Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 4 6 096 1 Printed by the Consumer ’s Cooperatives of the Ministry of Economy ’s Intellectual Property Co., Ltd. This paper has two standard specifications. Coffee X 297 pounds £ 7 A7 V. Description of the invention (added to the etchant (the purity of KS〇4 powder is generally about 99/0 or more), and sulfuric acid is generally added as an aqueous solution of about 95% by weight of h2S04. Note that the high potassium sulphate and sulphuric acid reconstruction method is theoretically a preferred embodiment when the introduction of gaseous ozone into an etchant that uses persalt salt will produce foam, for example when a surfactant is present in solution. It should be further noted that the previous regeneration reaction can be accomplished by directly adding persulfuric acid, which is commercially available, instead of a combination of potassium sulfate and sulfuric acid. To fully regenerate in this way is based on permanganate Etchant, generally added from about 2 to about 10 Percent sulfuric acid by weight. However, it is best to add about 2 to about 5 weight ratio of persulfuric acid. The timing of the regeneration step, or the addition of reagents to re-saturate the used oxidant or solute, at least Part of it is a function of the regeneration program used. For example, 'these reagents are added to schedule the visible changes in the etching solution. The addition occurs when the color of the solution changes from purple to purple-brown or' to ensure more efficient Process and prevent unnecessary delays, the addition can be continuous (such as when ozone is used to agitate the solution) or it can be performed after each wafer is removed from the solution. Additionally, by closely monitoring the etch process before and after The thickness of the wafer can determine the amount of silicon to be removed. Using the above equation, the amount of oxidant consumed can be determined, which can then be used to calculate " reoxidation " pieces that have been added at any given time The exact number of the agent " t * 〇—the incoming wafer preferably has a gbir of about 1-5 microns. However, it should be considered that the etching sequence may have a different gbir from that described here. ir and rough yang on the sun circle without departing from the scope of the present invention. • 21 · (Please read the precautions on the back before filling out this page)

460961 A7 B7 V. Description of the Invention (l9) Prior to the etched wafer, it is better that the wafer is pre-treated to ensure that the two surfaces of the wafer are clean and that it is not easy to be chemically changed and free of residues. This pre-processing can be performed by any device known in the art (see, for example, U.S. Patent No. 5,593,505). The illustrated etchant is particularly effective at reducing roughness. The ㈣ procedure generally involves contacting the wafer surface with an aqueous etchant solution. To about 30 minutes. However, the wafer is preferably in contact for about 2 to about 5 minutes. Etching procedures are believed to allow a certain level of achievable roughness and gloss, which are generally equal to those obtained by preliminary polishing 'while removing significantly less silicon than using a nitric acid-based etchant. For example, using a nitric acid-based etchant to remove about 10-15 micrometers of stone eve from each side of a wafer will result in a surface roughness of about 0.008 to about 0.13 micrometers Ra. In contrast, the etchant described herein can achieve the same coarse chain by removing less than about 8 microns from each surface, and preferably only about 2 microns to about 5 microns. The etchant described herein can achieve a roughness of less than about ㈣i μm by removing 15-3 μm from each surface, which can be compared with the roughness of a preliminary polished wafer. This relatively small amount of removal is the reason why this program is classified as " 微 姓 刻 ". The engraving procedure is preferably produced-a wafer having a thick chain of about ㈣ to about Qi microns Ra. Micro-etched wafers may have a coarse sugar content of about 0.001 to about 0.02 microns. Finally, the etching process can produce a wafer having a roughness of about ㈣m Ra or less. The results of this procedure are comparable to conventional polishing procedures, which are generally performed in accordance with a standard etching step. A method of removing light is a mechanochemical procedure, which involves a polishing pad and a polishing solution (refer to, for example, US Patent No. I_______). -22- This paper standard is applicable to the Chinese National Standard 7 ^ 4 46 0961

Description of the Invention ((Please read the precautions on the back before filling in this page) 5: '3W, 451)' It produces a circle with a roughness of about 100,000 microns h, and moves from the wafer surface Except for dreams of about 7 to about 15 microns. Therefore, the etching process is also considered to reduce manufacturing costs. By producing wafers with a quality similar to that of polished wafers, the cost and time associated with steps in the wafer manufacturing process can be effectively eliminated. Example # 1. A mechanochemical process using a slurry containing a permanganic acid-based etchant and an optional standard particulate material can be used to produce a completed wafer in less time. This is because the thinning and removal of the boundary layer is less than when the acid etching and polishing operations are performed separately. These etchants can be applied to slurry-like polishing pastes in accordance with standard polishing sequences. This integration of acid and mechanical polishing will achieve low surface roughness through the chemical effects of the etchant used and the mechanical effects of the particulate matter / polishing pad. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs However, it should be noted that if the etching process is to be used as a replacement for standard polishing techniques, the current polishing pads may need to be improved. If this procedure is to make such commercially viable cycle time such an improvement, such an improvement would be needed, because standard acid-resistant polishing pads generally cannot withstand the wear of particles that typically occur on the polishing pad surface for a time sufficient to make the procedure economically viable. As such, cushions that can withstand the general abrasion typically do not withstand the extremely corrosive hydrofluoric environment. Therefore, the benefits of integrating the etchant and polishing step in question cannot be fully realized until the polishing pad technology can produce a pad with sufficient resistance to acids and abrasion. The etching process is generally performed at room temperature (i.e., about 20 to about 25); that is, the general etching process is performed at room temperature without adding heat. Although you can use about 25 ° C to about 45. 〇The temperature in the range should pay attention to the latest experience. -23 · This paper size is applicable to the national standard (CNS) A4 specification (210 X 297 public love) 460961 A7 ---------- --- B7 _I__ V. Description of the invention (2i) It is suggested that the temperature in this etching process generally does not play a meaningful role. After the cutting or micro-etching operation, the PACE operation is performed, as disclosed in the joint designation application series No. 09 / 030,912, which is dated January 26, 1998, and is incorporated herein by reference. The pACE operation rounds and improves wafer thickness consistency. In short, the thickness profile data of the wafer is generated little by little in the PACE operation, and this data is mapped by the position two function on the front surface of the wafer. The profile data is generated at enough separation locations (generally thousands of separation locations) to guarantee the entire surface of the covered wafer. A thickness measurement tool is used to generate this data. The tool can be a capacitor, optical stem #, FTIR, or a mechanical (eg micrometer) thickness measurement tool. However, it is best to use a capacitor thickness measurement tool to determine, which has a resolution of at least about 0.5 meters, and a resolution of about 0 μm is more suitable. A suitable capacitance measurement tool is commercially available from ADE Corporation, Newton, MΛ, under the ULTRAGAGE trademark, such as ULTRAGAGE 9700, and from IpEC predsión, ΐη〇.

Bethel, acquired under the Conn_j AcuFlat trademark. Introduce silicon wafers in operation; the space between the capacitors in the row of these tools will cause the capacitance value to change. The change in m value will be related to the thickness of the wafer and its equivalent dielectric constant. The reduction of the GBIR, SBIR, and / or SFQR of a wafer can be calculated using an algorithm. It is calculated using the thickness profile data and the target thickness value of the wafer 'Tt'. For example, the amount of material to be removed can be borrowed It is determined by subtracting the target thickness and Tt. From the thickness profile data at each separation point. The difference between the two values constitutes -24- sheet paper scale thorn in Guan Jiapi (CNS) A4 specification ⑵ "297 public reply" —- (Please read the note on the back? Matters before filling out this page) Order --------- line. Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs ^ 6 0961 A7 —— * ^ * i »^ ^ * 5. Description of the Invention (η) At each position of the sun circle, the surface must be removed to achieve the target thickness, t amount of material, and to minimize GBIR, SBIR, and / or sfqr. Once the amount of material removed from each location on the wafer is determined, this data is processed and converted into a dwell time versus location map, which is used to control the material removal tool during the material removal step. This material removal step can be performed using any tool that can locally and accurately remove material from a small area on the front surface of the wafer. However, it is preferably a PACE removal tool of the type described in U.S. Patent Nos. 4,668,366, 5,254,830, 5,291,415, 5'375'064, 5,376,224, and 5,491,571, which are commercially available from IPEC / Precision, Inc., for example, model pwS-200 / 3〇00 obtained by Shitian. After the PACE material removal step, the wafer has a GBIR of less than 1 micron, and preferably a GB of less than about 0.4 micron.] [r. In addition, the wafer has an SFQR of less than 0.7 microns for any local spot 20 mm by 20 mm. Those having less than about 0.4 micrometers are more suitable, and less than about 0.25 micrometers are more suitable. The wafer has an SFQR of less than about 0.4 micrometers at any local site of 25mm X 25mm, less than about 0.018 is more suitable, preferably less than about 0.13 microns, and more preferably less than about 010 microns. The final GBIR, SBIR, and SFQR of the wafer are diagrams used in the material removal step.

The wafer's thickness and accuracy are accurately mapped to make the wafer thin. During the PACE material removal step, it is best to remove about 4-6 microns of material from the wafer, and it is most appropriate to remove at least about 50 microns of material during the material removal step. The amount of material removed mainly depends on the flatness of the incoming wafer and 'I ___-厶 3 · This paper size applies to China National Standard (CNS) A4 specifications (210 X 297 public) -25 to 460961 A7 B7 5 2. The damage on the wafer surface of invention description (23) depends on the damage. Before and / or after material removal, the wafer can choose whether to clean to remove contaminants, such as substances introduced during the initial planarization step, or precipitation on the wafer surface due to plasma during material removal Reaction by-products. The wafer can be cleaned using any suitable cleaning procedure, which does not significantly affect the thickness profile of the wafer. Such cleaning procedures are technically well known and include, for example, the RCA method (described in FShimura's work ^ ^ (Semiconductor Silicon Pryct.i

Technology) (Academic Press 1989), pages 189-191), or—appropriate wafer flushing. After the material removal step, the wafer is subjected to-final polishing (also known as "contact" polishing) to further reduce surface roughness. Plasma wafer thinning procedures generally leave a significant amount of surface roughness on the silicon wafer surface, as measured, such as with an atomic force microscope (AFM). In this way, the roughness of the plasma-etched wafer surface is preferably reduced to less than this roughness. The root-mean-square surface is rough, RMS, reduced to about 奈 of nanometer on an area of 10mm x 10mm, 値 of about 0.02nm on 10mm x 10 mm area is more suitable, and one. An area of 10 mm X 10 mm is approximately 0.1 nm, but it is not appropriate. The final polishing procedure is non-reflective (foggy). An unpolished wafer includes high and low cycle roughness components on its surface. High-peripheral roughness results in high light scattering on the surface, which results in fogging. Final polishing minimizes surface roughness at high and low cycle rates and thus reduces haze. Polishing can be performed in a chemical / mechanical polishing procedure, using, for example, dilute colloidal silicon paste and traditional polishing equipment. -26-This paper size applies to China National Standard (CNS) A4 (210 X 297 mm Γ —- ------- Order --------- Line (Please read the precautions on the back before filling this page)

4 6 096 1 V. Description of Invention (24). The final polishing step is different from the preliminary or intermediate polishing step, and these steps are not performed in the program flow of the present invention. Final polishing, as used in this description, refers to a procedure with several characteristics that differ from preliminary or intermediate polishing. For example, final polishing applies less polishing pressure than primary / intermediate polishing, typically between 2-4 psi, compared to 6-9 in the primary / intermediate. The final polishing uses a softer polishing pad, which generally has a compressibility between 8-20% and a direct viewing height between .30-.53 mm. The slurry contains particles with more tightly controlled sizes, typically between about 20-75 nm, compared to about 10-15 nm in the preliminary / intermediate. Final polishing uses a mild chemical, such as ammonium hydroxide, compared to sodium hydroxide in the preliminary / intermediate. It is preferred to remove w-circle thicknesses of less than about 1 micron in the final polishing step. If the silicon slurry is not diluted before use, the polished wafer will not be as smooth as the wafer processed with the diluted slurry. About one minute of silicon paste dilutes about ten minutes of deionized water. Importantly, the program flow of the present invention is more reliable than the traditional process of processing wafers, which meets the better flatness specifications discussed above and the National Technology Roadmap fni ·

(Semiconductors) (full citations cited above) are considered to be more reliable because the simultaneous #edge grinding (grind), etching and PACE operations generally include grinding (lappin magic and preliminary / The fact that the procedure of intermediate polishing is more correct. As such, the wafer yield in this specification is expected to be at or near 100%. Considering the above, it can be seen that several goals of the present invention have been achieved and others Favorable results. -27- This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297). --------------------- Order- --------- line, L (Please read the note on the back? Matters before filling out this page) Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs means printed by the Consumers’ Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 096 1 A7 B7 V. Description of the invention (25 Because different modifications can be made in the above structure without departing from the scope of the invention, all the two included in the above description or shown in the drawings must be interpreted for illustrative purposes. It is not a restriction ^ *, and each has its own meaning 1 28-This paper size applies to China Associate (CNS) A4 size (210 X 297 mm) (Please read the back of the precautions to fill out this page)

Claims (1)

460961 A8 B8 C8 D8 Six, a method of processing semiconductor wafers. The wafer is cut from a single crystal ingot with front and back surfaces and a round periphery. The method includes the following steps' in order: () grinding Improve the thickness of the wafer to improve wafer thickness uniformity and reduce undulation; and # ㈣wafer to reduce stress in the wafer and smooth the surface; 执行 Perform plasma-assisted chemical etching (PACE) on the edge circle In order to flatten the wafer and improve the thickness-consistency of the wafer. 2. For the method of applying for the first paragraph of the patent application park, the wafer processing does not require any preliminary polishing steps, and does not require any polishing steps. 3. The method according to item 2 of the patent application, wherein the step of polishing the wafer includes: simultaneously polishing the front and back surfaces of the wafer, and wherein the step of etching the wafer includes etching the front and back surfaces of the wafer. 4. If the method of item 3 in the patent is requested, the step of counting PACE on the wafer includes performing ME on the front and back surfaces of the wafer. 5. If the method of applying for patent No. 3 is applied on the wafer, . The steps of PACE include performing p on one of the wafer surfaces. D6. If the method of applying for a patent covers the first item, further includes-burden. The step of rounding for shipment is followed by this step where the procedure does not require any grinding steps or preliminary polishing steps for cutting and wrapping. Step < 7. The method according to item 6 of the patent application, wherein the circle is placed in a polishing apparatus for processing, which includes abrasion: the abrasive grains having a size in the range of 3-10 microns. , ^ Paper scale & towel reward home solution (¾¾ecret xnnnn (Please read the precautions on the back before filling out this page) nnn 1 ---- ~ "1Τ —-------- ^ — V- ------ -29. 46 096 1 A8 B8 C8 D8 VI. Application scope of patent 8. If the method of applying for patent field No. 7 method, the etching step includes a micro-etching process, which includes contacting the wafer —High-gloss etchant: and wherein the etching step removes an amount equal to the size of the abrasive grains of the grinding wheel from the surface of each wafer. 9. As in the method of applying for patent U, wherein the polishing step etching step makes the wafer flat, Will reduce the local location of any 25mmx 25mm wafer (locally, the location is most expected to reduce the plane to more than about 0.25 micrometers.) 10. A method of processing a semiconductor wafer, the wafer is from a single crystal ingot Cut and have front and back surfaces and a round perimeter. The method includes the following steps, in order: (a) Polishing the wafer to improve the thickness consistency of the wafer and reducing wafer undulations; ^ (b) using a high Gloss etchant to micro-etch the wafer to remove less than about 15 microns in total Circular thickness, which reduces the stress in the wafer and smoothes the front and back surfaces of the wafer; (c) performing plasma-assisted chemical etching on one of the front and back surfaces of the wafer to flatten the wafer and improve the wafer's Consistent thickness; and (d) Final polishing of the front surface of the wafer; Wafer processing does not require any preliminary polishing steps and does not require any grinding steps. ___ -30- ^ Zhongguanjia Standard for Paper Size 5 < CNS) A4 specification (210 X 297 public love) (Please read the note on the back? Matters before filling out this page) --line. -Nnnn.