JP3775176B2 - Semiconductor wafer manufacturing method and manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor wafer manufacturing method and a manufacturing apparatus capable of obtaining ultra-high flatness that can cope with high integration at low cost.
[0002]
[Prior art]
As a technique for flattening a semiconductor wafer such as a silicon wafer, a method of polishing a surface to be processed on the front surface or the back surface is used. As a device for performing such polishing, a double-side polishing device capable of obtaining particularly high flatness is used.
[0003]
As a general double-side polishing apparatus, a plurality of wafer carriers holding a plurality of wafers are arranged between upper and lower surface plates having a polishing surface, and a sun gear is arranged in the center of these wafer carriers to rotate each wafer carrier. A so-called sun gear type double-side polishing apparatus is known. In addition, a so-called oscillating carrier type double-side polishing apparatus or the like is used in which a wafer carrier disposed between rotating upper and lower surface plates does not rotate without using a sun gear, and a held wafer is swung. Yes.
[0004]
In the oscillating carrier type double-side polishing apparatus, for example, as proposed in Japanese Patent Laid-Open No. 11-254302, the diameter of the wafer carrier is larger than that of the surface plate, and the periphery of the wafer temporarily moves outward from the surface plate during polishing. Since it is easy to provide an overhang mechanism that comes out, there is an advantage that polishing dripping around the wafer that occurs during polishing can be suppressed.
[0005]
In these double-side polishing apparatuses, a polishing liquid containing abrasive grains (such as silica) is used in mechanical chemical polishing, and the front and back surfaces of the wafer are similarly polished. However, since the wafer polished by the double-side polishing machine is polished not only on the front surface but also on the back surface side, it is difficult to distinguish the mirrored front and back surfaces, and when the back surface of the wafer is attracted by an electrostatic chuck or the like There was an inconvenience in handling that it was difficult to release the wafer. For this reason, there is a demand for a wafer having a high flatness similar to that which has been polished on both sides and not polished on both sides.
[0006]
In order to meet such a demand, a technique for polishing only one side using a double-side polishing apparatus effective as a high planarization processing method has been proposed. For example, conventionally, LTO (Low Temperature Oxide) or the like is deposited on the back side of the wafer by heat treatment before polishing, and when polishing with a double-side polishing machine, the back side is protected with LTO and only the front side is polished. Techniques to do this have been proposed. For example, Japanese Patent Laid-Open No. 10-303154 proposes a technique in which an oxide film is provided on a non-polished surface of a silicon wafer using a CVD apparatus and then mechanochemical polishing is performed using a double-side polishing apparatus.
[0007]
[Problems to be solved by the invention]
However, the following problems remain in the conventional polishing technique. That is, as a technique for polishing only one side using a double-side polishing apparatus, when LTO or the like is formed on the back surface of the wafer by heat treatment before polishing, the manufacturing cost increases due to the addition of LTO film formation and removal processes. However, there is a possibility that problems such as a decrease in throughput, contamination due to a thermal process, and generation of particles during film removal may occur. In addition, when using a polishing liquid containing many abrasive grains as in mechanochemical polishing, there is a disadvantage that fine processing damage is likely to occur on the surface due to the abrasive grains, and the cost of manufacturing the abrasive grains is high. There has been a demand for cost reduction.
[0008]
The present invention has been made in view of the above-mentioned problems, and it is not necessary to add a step of forming a protective film such as LTO, and even with single-side polishing, high flatness similar to double-side polishing can be obtained at low cost. An object of the present invention is to provide a semiconductor wafer manufacturing method and manufacturing apparatus.
[0009]
[Means for Solving the Problems]
  The present invention employs the following configuration in order to solve the above problems. That is, in the semiconductor wafer manufacturing method of the present invention, a pair of surface plates having a polishing surface sandwiching the semiconductor wafer from the front and back sides and the semiconductor wafer are relatively moved, and a polishing liquid is supplied to the polishing surface to provide a semiconductor. A method for manufacturing a semiconductor wafer having a polishing step for polishing a wafer, wherein only the thin film on the front side is removed from the thin films on the front and back surfaces of the semiconductor wafer that are left in the natural state before the polishing step or during the cleaning. After the surface film removing step and the surface film removing step, the polishing liquid is supplied at a polishing rate higher than the polishing rate for the thin film to selectively chemically polish the surface side of the semiconductor wafer. And a surface polishing step.
  In the surface polishing step, the polishing rate of the surface of the silicon wafer is the means in which the thickness of the oxide film is 0.5 to 10 nm or the means in which the abrasive concentration in the alkaline solution is 0%. Means set so as to be higher than the polishing rate of the back surface of the silicon wafer can also be adopted.
[0010]
In this method of manufacturing a semiconductor wafer, in the surface film removal step, by removing only the thin film on the front side from the thin film on the front and back surfaces of the semiconductor wafer that was left in the natural state before the polishing step or during the cleaning, In the surface polishing step, the surface of the semiconductor wafer is selectively chemically treated by supplying the polishing liquid whose polishing rate for the material of the semiconductor wafer is higher than the polishing rate for the thin film. By polishing (chemical polishing), the polishing rate on the back side is low and the thin film remains, and the polishing hardly progresses. On the other hand, the polishing rate on the surface side is high and the polishing is performed substantially. Become. In addition, since it is chemical grinding | polishing, it can prevent that the thin film of the back surface side is grind | polished and removed by a mechanical action, while grind | polishing the surface side. In other words, by performing chemical polishing instead of mechanochemical polishing, an oxide film generated during normal cleaning process or natural standing without adding a protective film forming process that forms a thick oxide film on the back surface. Or the like can sufficiently function as a protective film.
[0011]
  The semiconductor wafer manufacturing apparatus of the present invention relatively moves a pair of surface plates having a polishing surface sandwiching the semiconductor wafer from the front and back sides and the semiconductor wafer, and supplies a polishing liquid to the polishing surface to supply the semiconductor wafer. An apparatus for manufacturing a semiconductor wafer to be polished, wherein the polishing liquid is supplied at a polishing rate higher than a polishing rate for a thin film on the surface of a semiconductor wafer generated during natural standing or cleaning before the polishing. A polishing liquid supply mechanism is provided, and the polishing surface in contact with the surface of the semiconductor wafer is composed of a polishing cloth having a structure or material having a higher polishing speed of the semiconductor wafer than the polishing surface in contact with the back surface of the semiconductor wafer. To do.
  Another polishing liquid supplied by the separate polishing liquid supply mechanism may be an alkaline solution having an abrasive concentration of 0% by weight to 1% by weight.
[0012]
In this semiconductor wafer manufacturing apparatus, the polishing liquid supply mechanism allows the polishing liquid to have a polishing speed higher than the polishing speed for the thin film on the surface of the semiconductor wafer generated during natural standing or cleaning before the polishing. Since the polishing surface that is in contact with the surface of the semiconductor wafer is composed of a polishing cloth having a structure or material that has a higher polishing speed of the semiconductor wafer than the polishing surface that is in contact with the back surface of the semiconductor wafer, the thin film on the surface side during polishing is It is polished and removed faster than the back side. And since the thin film remains on the back side, the polishing rate is low and polishing hardly progresses, whereas the thin film is removed on the front side, so that the polishing rate is high and good polishing is performed. It will be in a polishing state.
[0013]
That is, in the above-described semiconductor wafer manufacturing method and manufacturing apparatus, both the surface plates in contact with the front and back surfaces move relatively as in the double-side polishing apparatus, but only the front surface is polished. Single-side polishing is possible with accuracy. In addition, since a thin film such as an oxide film naturally generated during natural standing or cleaning, which is a process normally performed before the polishing process, is used, there is no need to introduce a special protective film forming process for protecting the back surface. .
[0014]
In the method and apparatus for manufacturing a semiconductor wafer according to the present invention, the semiconductor wafer is a silicon wafer, the thin film is an oxide film, and the polishing liquid has an abrasive concentration of 0% by weight or more and 1% by weight. % Alkaline solution is preferred.
That is, in these semiconductor wafer manufacturing methods and manufacturing apparatuses, since the polishing liquid is an alkaline solution having an abrasive grain concentration of 0 wt% or more and 1 wt% or less, there is almost no mechanical polishing action by the abrasive grains, and the alkaline solution Polishing is carried out only by the chemical polishing action by the oxide, so that the oxide film on the back surface, ie₂Is hardly polished. For example, even a very thin oxide film of 0.5 nm to 10 nm functions as a protective film, and only silicon on the surface can be polished well. An abrasive solution having an abrasive concentration of 0% by weight, that is, an alkaline solution containing no abrasive grains is most suitable. However, if it is 1% by weight or less, the mechanical polishing action by the abrasive grains is higher than the chemical polishing action by the alkali. Almost negligible, chemical polishing rather than mechanochemical polishing. Further, by reducing the abrasive grains, it is possible to reduce fine processing damage to the surface and reduce the cost of the polishing liquid.
[0015]
In the conventional example described in JP-A-10-303154 described above, the back side is SiO.₂The polishing rate is only low because it is protected with a large amount of SiO2 on the back side by mechanochemical polishing.₂Is polished with abrasive grains in the polishing liquid. Therefore, the SiO2 on the back side that has been scraped off.₂Although there is a disadvantage that the film causes damage to the mirror-polished surface on the front side, in the present invention, the mechanical polishing action can be ignored, and the polishing amount on the back side is ideally close to zero, and the surface as described above There is almost no influence on the side. Specifically, even in the case of a backside oxide film of about 0.5 nm, the film remains even after polishing for 1 hour in the present invention, and it can be considered that the film is not substantially polished. In the above prior art, the backside SiO 2₂In the case of the present invention, a film attached in a normal state, i.e., a film attached in a normal state, i.e., naturally attached to the wafer in an atmosphere etc. Further, it has an advantage that it can be sufficiently processed with an extremely thin film, such as an oxide film or an oxide film attached in a cleaning process.
[0016]
Furthermore, in the semiconductor wafer manufacturing method of the present invention, it is preferable that the oxide film is removed with a hydrofluoric acid-based etchant in the surface film removal step. That is, if a hydrofluoric acid-based etching solution is used, SiO, which is an oxide film formed on the surface side of the silicon wafer.₂Can be removed satisfactorily.
[0017]
In the semiconductor wafer manufacturing apparatus of the present invention, it is preferable that only the polishing surface in contact with the surface of the polishing surface in contact with the front and back surfaces of the semiconductor wafer is composed of a fixed abrasive polishing cloth containing abrasive grains.
That is, in this semiconductor wafer manufacturing apparatus, only the polishing surface in contact with the front surface is composed of a fixed abrasive polishing cloth containing abrasive grains, and the polishing surface in contact with the back surface is composed of a polishing cloth not containing abrasive grains. Only the thin film on the surface side in contact with the fixed abrasive polishing cloth is polished, and the thin film remains unpolished on the back surface side in contact with the polishing cloth not containing abrasive grains. Thus, by providing the fixed abrasive polishing cloth only on the surface side, there is an advantage that the surface oxide film removing operation as the pretreatment described above becomes unnecessary.
[0018]
Further, in the semiconductor wafer manufacturing apparatus of the present invention, the polishing surface in contact with the surface of the semiconductor wafer is composed of a polishing cloth having a plurality of grooves formed on the surface, and the polishing surface in contact with the back surface of the semiconductor wafer is flat. It is preferable that the surface is composed of a polishing cloth having a smooth surface.
That is, in this semiconductor wafer manufacturing apparatus, since the polishing cloth in contact with the back surface is a flat surface, the thin film on the back surface is hardly polished, whereas the polishing cloth in contact with the surface is a surface on which a plurality of grooves are formed. Therefore, the polishing rate is higher than that of the flat backside polishing cloth, and the thin film on the surface is polished and removed.
[0019]
Further, in the method for producing a semiconductor wafer of the present invention, the front and back surface polishing step of polishing the back surface simultaneously with the surface of the semiconductor wafer by supplying a polishing liquid having an abrasive concentration exceeding 1% by weight after completion of the surface polishing. May be provided.
In the semiconductor wafer manufacturing apparatus of the present invention, it is preferable that the polishing liquid supply mechanism includes another polishing liquid supply mechanism that supplies another polishing liquid having a higher abrasive grain concentration than the polishing liquid.
That is, in these semiconductor wafer manufacturing methods and manufacturing apparatuses, the glossiness of the back surface can be controlled by supplying a polishing liquid having an abrasive concentration exceeding 1% by weight and polishing the back surface together with the front surface.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment according to the present invention will be described below with reference to FIGS.
[0021]
1 to 3 show a silicon wafer polishing apparatus according to the present embodiment, which moves in the same manner as the swing carrier type double-side polishing apparatus described above, that is, between the rotating upper and lower upper surface plates 1 and 2. This is a single-side polishing apparatus for polishing only the surface S of the silicon wafer W, which causes the wafer carrier 3 arranged in the above to move in a circular motion that does not rotate, and to rotate the held silicon wafer W.
[0022]
That is, this polishing apparatus is arranged between an upper surface plate 1 and a lower surface plate 2 which are arranged in the opposite directions and rotate in the opposite direction around the same axis, and a plurality of silicon wafers W arranged between the upper surface plate 1 and the lower surface plate 2. A flat plate wafer carrier 3 to be held, a surface plate driving mechanism 4 for rotating the upper surface plate 1 and the lower surface plate 2, and a carrier driving mechanism 5 for rotating the wafer carrier 3 are provided.
[0023]
The upper surface plate 1 and the lower surface plate 2 have a polishing cloth 6 bonded to their respective surfaces, and these polishing cloths 6 constitute a polishing surface. As the polishing cloth 6, a nonwoven fabric having a flat surface is used.
The upper surface plate 1 is provided with a plurality of supply holes 1a (one supply hole 1a is representatively shown in FIG. 3), and each supply hole 1a is a polishing liquid for supplying a polishing liquid to the polishing surface. It is connected to the supply mechanism 7.
[0024]
The polishing liquid supply mechanism 7 has a polishing rate for silicon having an oxide film (SiO2).₂) And a first supply mechanism 8 capable of supplying an alkaline solution having an abrasive grain (silica) concentration of 0 wt% or more and 1 wt% or less as a polishing liquid higher than the polishing rate, and an alkaline solution having an abrasive grain concentration exceeding 1 wt% And a second supply mechanism (separate polishing liquid supply mechanism) 9 capable of supplying a polishing liquid for adjusting glossiness, and one of the first supply mechanism 8 and the second supply mechanism 9 can be arbitrarily selected. Yes.
[0025]
The polishing liquid supplied by the first supply mechanism 8 is preferably an alkaline solution having an abrasive grain concentration of 0% by weight, that is, no abrasive grains.
Examples of the alkaline solution include an inorganic alkali (KOH, NaOH, etc.), an organic alkali, and a mixed solution thereof. In this embodiment, the alkaline solution is an organic alkali and contains an amine as a main component (for example, piperazine, ethylenediamine, etc.). Is used.
[0026]
The wafer carrier 3 is larger in diameter than the upper surface plate 1 and the lower surface plate 2, and is formed of, for example, a glass epoxy plate, and a plurality of holding holes 3a for holding the silicon wafer W in a loosely fitted state are formed. The wafer carrier 3 is set to be slightly thinner than the thickness of the silicon wafer W by a predetermined amount. The silicon wafer W held in the holding hole 3a can rotate in the holding hole 3a.
[0027]
The surface plate drive mechanism 4 includes drive sources 10 and 11 such as motors that are connected to the upper surface plate 1 and the lower surface plate 2 and rotate them.
The carrier drive mechanism 5 causes the wafer carrier 3 to make a circular motion that does not rotate in a plane parallel to the front and back surfaces thereof, and is held in the holding hole 3 a and held between the upper surface plate 1 and the lower surface plate 2. Is swiveled. That is, the carrier drive mechanism 5 is connected to the annular carrier holder 12 attached to the outer periphery of the wafer carrier 3, four eccentric members 13 rotatably connected to the carrier holder 12, and these eccentric members 13. And an eccentric member synchronizing mechanism 14 for synchronously moving these in a circular motion.
[0028]
The eccentric member 13 has a columnar shape, and a rotary shaft portion 13a protrudes from the lower surface, and an eccentric shaft portion 13b protrudes from the upper surface at a position eccentric from the rotation shaft of the rotary shaft portion 13a. Further, the eccentric member 13 is supported by allowing the rotary shaft portion 13a to rotate through a support hole 14a provided in the base 14 of the apparatus.
The carrier holder 12 is provided with four through holes 12a spaced on the circumference at equal intervals from each other, and eccentric shaft portions 13b are rotatably inserted into the through holes 12a, respectively.
[0029]
The eccentric member synchronization mechanism 14 includes a timing chain 15 wound around the rotation shaft portion 13a of each eccentric member 13, and a drive motor 17 connected to the rotation shaft portion 13a of one eccentric member 13 by a motor side gear 16. It has. That is, the motor-side gear 16 provided on the output shaft of the drive motor 17 is engaged with the shaft-side gear 18 provided at the lower end of the rotating shaft portion 13a, and when the drive motor 17 is driven, the motor-side gear 16 is driven. One eccentric member 13 rotates via the shaft side gear 18 and the other eccentric member 13 rotates simultaneously and synchronously via the timing chain 15.
[0030]
At this time, each eccentric member 13 rotates around the rotation shaft portion 13a, but the eccentric shaft portion 13b turns around the rotation shaft of the rotation shaft portion 13a. That is, the carrier holder 12 and the wafer carrier 3 supported by the eccentric shaft portion 13b perform a circular motion that does not rotate by the turning of the eccentric shaft portion 13b. Accordingly, the silicon wafer W held on the wafer carrier 3 also turns. In addition, the wafer carrier 3 moves so that the periphery of the silicon wafer W temporarily moves outward from the upper surface plate 1 and the lower surface plate 2, so-called overhang.
[0031]
Next, the silicon wafer polishing method (semiconductor wafer manufacturing method) according to the present embodiment will be described with reference to FIG.
[0032]
[Surface oxide film removal process] (Surface film removal process)
First, as shown in FIG. 4A, oxide films (thin film: SiO2) on the front and back surfaces of the silicon wafer W generated during cleaning before polishing (for example, ozone cleaning) or during conveyance.₂) Of OX, as shown in FIG. 4B, only the oxide film OX on the surface S is removed in advance with a hydrofluoric acid-based etching solution (for example, hydrofluoric acid (HF)). Since the oxide film OX on the surface S is an extremely thin oxide film, it can be easily removed with a hydrofluoric acid-based etching solution.
When SC1 cleaning is performed before polishing, the oxide film formed during the cleaning is also included in the front and back oxide films OX, and only the oxide film on the front surface S side is removed in this step. These oxide films are extremely thin with a thickness of 0.5 nm to less than 10 nm.
[0033]
[Surface polishing process]
Next, the silicon wafer W is set in the holding hole 3a of the wafer carrier 3, the wafer carrier 3 is attached to a polishing apparatus, and the surface S is polished as shown in FIG. That is, the upper surface plate 1 and the lower surface plate 2 are rotated by the surface plate driving mechanism 4 and the wafer carrier 3 is circularly moved by the carrier driving mechanism 5 so as not to rotate. At the same time, the first supply mechanism 8 of the polishing liquid supply mechanism 7 supplies the polishing liquid of the alkaline solution to the polishing surface.
[0034]
At this time, only the oxide film OX on the front surface S of the oxide film OX on the front and back surfaces of the silicon wafer W is removed, and only the oxide film OX on the back surface R side is left as a protective film.₂The polishing solution of an alkaline solution with a large polishing selectivity ratio selectively polishes the surface S of the silicon wafer W, so that the polishing rate on the back surface R side is low and the oxide film OX remains and the polishing hardly progresses. On the surface S side, the polishing rate is high and good polishing is performed, so that the single-side polishing state is substantially achieved.
[0035]
Moreover, since the polishing liquid is an alkaline solution having an abrasive concentration of 0 wt% or more and 1 wt% or less, there is almost no mechanical polishing action by the abrasive grains, and polishing is performed only by the chemical polishing action by the alkaline solution. Oxide film OX on the back surface R, that is, SiO₂It is possible to satisfactorily polish only the silicon on the surface S.
[0036]
[Back polishing process]
In addition, since the back surface R which is not polished is rough and has a low glossiness, particles may enter the irregularities of the back surface R and cause dust generation. For this reason, a certain degree of high glossiness may be required for the back surface R.
In such a case, after the polishing of the surface S is finished, as shown in FIG. That is, the second supply mechanism 9 supplies a polishing liquid (for example, an abrasive concentration of 5% by weight) having an abrasive grain (silica) concentration exceeding 1% by weight only to the polishing surface that is in contact with the back surface R of the silicon wafer W. Is polished until the desired glossiness is obtained.
[0037]
At this time, the polishing liquid for adjusting the glossiness has a higher abrasive grain concentration and a stronger mechanical action than the polishing liquid used for the front surface polishing. The oxide film OX is easily removed, and the back surface R is polished to increase the glossiness. For example, when the surface polishing is completed, the glossiness of the back surface R is about 70 to 90%. By polishing the back surface R by this back surface polishing process, the glossiness can be arbitrarily controlled to about 320%. Can do. In addition, since it is a short time polishing only for gloss control, there is almost no influence on the already polished surface S.
[0038]
As described above, in this embodiment, both the upper surface plate 1 and the lower surface plate 2 that are in contact with the front and back surfaces move relatively as in the double-side polishing apparatus, but only the surface S is polished, so that the same as in double-side polishing. It is possible to perform single-side polishing with an accuracy of. In addition, since an oxide film that naturally occurs during cleaning or natural standing, which is a process that is normally performed before the polishing process, is used, there is no need to introduce a special protective film forming process for backside protection, and the cost is low. Polishing can be performed.
[0039]
Next, a second embodiment according to the present invention will be described with reference to FIG.
[0040]
The difference between the second embodiment and the first embodiment is that, in the first embodiment, the polishing cloth 6 constituting the polishing surface of the upper surface plate 1 and the lower surface plate 2 is the same for both. In the polishing apparatus (semiconductor wafer manufacturing apparatus) of the second embodiment, the polishing surface of the lower surface plate 2, that is, the polishing surface in contact with the surface S of the silicon wafer W is the polishing surface of the upper surface plate 1, as shown in FIG. In other words, silicon and SiO 2 than the polished surface in contact with the back surface R of the silicon wafer W.₂This is because the grooved polishing cloth 19 is a polishing cloth having a structure with a high polishing rate.
That is, a normal flat polishing cloth 6 having no grooves on the surface is bonded to the upper surface plate 1 of the present embodiment, and a grooved polishing cloth 19 having a plurality of grooves 19 a formed on the surface is attached to the lower surface plate 2. It is glued.
[0041]
Furthermore, in the first embodiment, only the oxide film OX on the surface S side is removed in the surface oxide film removing step, and only the surface S is polished in the surface polishing step, whereas in the second embodiment, the surface oxide film OX is polished. Using the same polishing liquid as that used in the front surface polishing step of the first embodiment without performing the oxide film removal step, polishing is performed with the above polishing apparatus while leaving the oxide film OX on both the front and back surfaces, thereby oxidizing only the surface S. It differs in that the film is removed and polished.
[0042]
Therefore, in the polishing apparatus of this embodiment, since the flat polishing cloth 6 is in contact with the back surface R, the oxide film OX on the back surface R is hardly polished, whereas the grooved polishing cloth 19 is in contact with the surface S. The oxide film OX is polished and removed faster than the back surface S side.
[0043]
Since the oxide film OX on the back surface R remains at the time of polishing, the polishing rate on the back surface R side is low and the polishing hardly proceeds, whereas the oxide film OX is removed on the front surface S side, so that the polishing rate is high and good polishing is performed. Is performed, and is substantially in a single-side polished state. Thus, in this embodiment, since the surface oxide film removal process is unnecessary, the manufacturing cost can be further reduced.
[0044]
As another example of the present embodiment, the polishing surface in contact with the surface S of the silicon wafer W may be made of a polishing cloth made of a material having a higher polishing rate than the polishing surface in contact with the back surface R. That is, instead of the grooved polishing cloth 19 as a polishing cloth, a fixed abrasive polishing cloth containing abrasive grains in advance may be bonded to the lower surface plate 2. In this case, since only the polishing surface in contact with the surface S side is composed of the fixed abrasive polishing cloth, only the oxide film OX on the surface S side is removed by the mechanical action of the abrasive grains in the fixed abrasive polishing cloth. Thus, the surface S can be polished.
In the fixed abrasive polishing cloth, since the abrasive grains are included in the fixed state in the polishing cloth, the abrasive grains turn to the back surface R side to polish the oxide film OX on the back surface R like the free abrasive particles. Can be prevented.
[0045]
【Example】
Next, the above embodiment according to the present invention will be specifically described by way of examples.
FIG. 6 shows data when the polishing is performed according to the first embodiment. 6A shows a conventional single-side polishing method, FIG. 6B shows a conventional double-side polishing method, and FIG. 6C shows an example of the above embodiment. The histogram which showed the frequency with respect to (Ideal Reference) is shown. The polishing liquid used is a mixed solution of piperazine, aminoethylaminoethanol and KOH.
As can be seen from this polishing result, the flatness similar to that of double-side polishing could be obtained despite single-side polishing.
[0046]
The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in each of the above embodiments, the surface plates are arranged up and down, but the present invention may be applied to a vertical polishing apparatus in which the surface plates are arranged on both the left and right sides of the silicon wafer in a standing state.
In each of the above embodiments, the thin film formed on the front and back surfaces of the silicon wafer before polishing is an oxide film (SiO 2₂However, it may be another thin film formed during natural standing before cleaning or during cleaning. For example, an organic film generated during cleaning using an organic chemical before polishing may be used. In this case, a polishing liquid having a sufficiently higher polishing rate is used for silicon than for the organic film.
[0047]
In each of the above embodiments, the present invention is applied to a rocking carrier type polishing apparatus, but may be applied to other types of polishing apparatuses. For example, the present invention may be applied to the above-described sun gear type polishing apparatus.
Further, in each of the above embodiments, the semiconductor wafer is applied to a silicon wafer. However, the present invention may be applied to a method of manufacturing another semiconductor wafer, for example, a compound semiconductor wafer (gallium / arsenic wafer, etc.).
[0048]
【The invention's effect】
According to the method for producing a conductor wafer of the present invention, in the surface film removal step, only the thin film on the front side of the thin film on the front and back surfaces of the semiconductor wafer generated during natural standing or cleaning before the polishing step is removed, In the surface polishing step, the polishing liquid is supplied at a polishing rate higher than the polishing rate for the thin film to selectively chemically polish the surface side of the semiconductor wafer. The single-side polishing can be performed substantially only on the surface side.
[0049]
According to the semiconductor wafer manufacturing apparatus of the present invention, the polishing rate for the semiconductor wafer material is higher than the polishing rate for the thin film on the surface of the semiconductor wafer generated during the natural standing before the polishing or during the cleaning by the polishing liquid supply mechanism. The polishing surface that supplies the polishing liquid and is in contact with the surface of the semiconductor wafer is composed of a polishing cloth having a structure or material that has a higher polishing rate of the semiconductor wafer than the polishing surface that contacts the back surface of the semiconductor wafer. With the thin film on the side being polished and removed faster than the back side, and the back side is protected by the thin film, the single side polishing of only the front side can be performed by the polishing selectivity of the polishing liquid.
[0050]
That is, in the semiconductor wafer manufacturing method and manufacturing apparatus of the present invention, both the surface plates that contact the front and back surfaces move relatively as in the double-side polishing apparatus, so that single-side polishing is performed with the same accuracy as double-side polishing. Can do.
In addition, since a thin film such as an oxide film that naturally occurs during natural standing or cleaning, which is a process normally performed before the polishing process, is used, there is no need to introduce a special protective film forming process for protecting the back surface. , Ultra high flatness that is low cost, high quality, and high integration can be achieved by preventing the increase of manufacturing cost by adding protective film formation and film removal process, lowering of throughput and contamination and particle generation in thermal process Degree wafers can be obtained.
Furthermore, since the polishing liquid to be used does not contain or is very small, it is possible to suppress fine processing damage due to the abrasive grains and to reduce the cost of the polishing liquid.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part showing a polishing apparatus in a first embodiment according to the present invention.
FIG. 2 is a plan view showing a positional relationship between a surface plate and a wafer carrier of the polishing apparatus according to the first embodiment of the present invention.
FIG. 3 is a schematic enlarged sectional view showing the polishing apparatus according to the first embodiment of the present invention.
FIG. 4 is a schematic enlarged cross-sectional view showing a silicon wafer in each step of the polishing method according to the first embodiment of the present invention.
FIG. 5 is a schematic enlarged sectional view showing a polishing apparatus according to a second embodiment of the present invention.
FIG. 6 is a graph showing each flatness (frequency with respect to GBIR) after polishing in a conventional single-side polishing method, a conventional double-side polishing method, and a polishing method in an embodiment according to the present invention.
[Explanation of symbols]
1 Upper surface plate
2 Lower surface plate
3 Wafer carrier
5 Carrier drive mechanism
6 Abrasive cloth
7 Polishing fluid supply mechanism
8 First supply mechanism
9 Second supply mechanism (separate polishing liquid supply mechanism)
19 Abrasive cloth with grooves
OX oxide film
S Silicon wafer surface
R Back side of silicon wafer
W Silicon wafer (semiconductor wafer)

Claims (8)

A semiconductor wafer having a polishing process in which a pair of surface plates having a polishing surface sandwiching a silicon wafer from the front and back sides and the silicon wafer are relatively moved and a polishing liquid is supplied to the polishing surface to polish the silicon wafer. A manufacturing method comprising:
A surface film removing step of removing only the oxide film on the front side of the oxide film on the front and back surfaces of the silicon wafer generated during natural standing or cleaning before the polishing step with a hydrofluoric acid-based etching solution ;
After the surface layer removing process, abrasive concentration of the silicon wafer by supplying a 0 wt% or more than 1% by weight of the alkaline solution as the polishing liquid is higher than the polishing rate polishing rate of the material of the silicon wafer for the thin film A surface polishing step for selectively chemically polishing the surface side ;
A semiconductor wafer comprising a front and back surface polishing step for polishing a back surface simultaneously with the surface of the silicon wafer by supplying a polishing liquid having an abrasive concentration exceeding 1% by weight after completion of the surface polishing. Manufacturing method. In the manufacturing method of the semiconductor wafer according to claim 1,
A method of manufacturing a semiconductor wafer, wherein the oxide film has a thickness of 0.5 to 10 nm . In the manufacturing method of the semiconductor wafer of Claim 1 or 2,
A method for producing a semiconductor wafer, wherein the abrasive concentration in the alkaline solution is 0% . In the manufacturing method of the semiconductor wafer in any one of Claim 1 to 3,
The method of manufacturing a semiconductor wafer, wherein, in the surface polishing step, the polishing rate of the surface of the silicon wafer is set to be higher than the polishing rate of the back surface of the silicon wafer . A semiconductor wafer manufacturing apparatus for polishing a silicon wafer by relatively moving a pair of surface plates having a polishing surface sandwiching a silicon wafer from the front and back sides and the silicon wafer and supplying a polishing liquid to the polishing surface. ,
Abrasive concentration is less than 1 wt% 0 wt% or more as the polishing liquid is higher than the polishing rate of oxide film polishing rate of the silicon wafer surface generated during natural standing or during cleaning before the polishing of the material of the silicon wafer A polishing liquid supply mechanism for supplying an alkaline solution of
Polished surface in contact with the surface of the silicon wafer, the polishing rate of the silicon wafer than the polishing surface in contact with the backside of the silicon wafer is constituted by the polishing cloth high structural or material,
The apparatus for manufacturing a semiconductor wafer, wherein the polishing liquid supply mechanism includes another polishing liquid supply mechanism for supplying another polishing liquid having a higher abrasive grain concentration than the polishing liquid . In the manufacturing apparatus of the semiconductor wafer of Claim 5,
Of the polishing surfaces in contact with the front and back surfaces of the semiconductor wafer, only the polishing surface in contact with the front surface is composed of a fixed abrasive polishing cloth containing abrasive grains. In the semiconductor wafer manufacturing apparatus according to claim 5 or 6,
The polishing surface in contact with the surface of the semiconductor wafer is composed of a polishing cloth having a plurality of grooves formed on the surface,
An apparatus for manufacturing a semiconductor wafer, wherein a polishing surface in contact with the back surface of the semiconductor wafer is made of a polishing cloth having a flat surface. In the semiconductor wafer manufacturing apparatus according to any one of claims 5 to 7,
Another polishing liquid supplied by the separate polishing liquid supply mechanism is an alkaline solution having an abrasive concentration of 0 wt% or more and 1 wt% or less .

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