JP2007067071A - Method and device for semiconductor wafer polish - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor wafer polishing method which prevents the dust adhesion in the polishing process of a semiconductor wafer, and to provide a semiconductor wafer polish device. <P>SOLUTION: The semiconductor wafer polishing method comprises a first process for polishing a semiconductor wafer surface by pressing the semiconductor wafer to a platen stuck by revolving polishing cloth, while supplying polishing fluid with a first pH value (x) containing polishing grains; and a second process for carrying out chemical polish of the semiconductor wafer by pressing the semiconductor wafer to the platen, while supplying chemical with a second pH value (y) subsequently after the end of the first process. The relation between the first pH value (x) and the second pH value (y) is set up as ¾x-y¾<4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor wafer polishing method and a semiconductor wafer polishing apparatus that prevent adhesion of contaminants to a semiconductor wafer surface in a semiconductor wafer polishing step.

  In manufacturing an integrated circuit or the like by incorporating fine circuit elements into a semiconductor wafer, it is necessary to wrap, etch, and polish the semiconductor wafer in advance to finish at least one surface of the semiconductor wafer into a mirror surface.

  FIG. 3 shows a typical semiconductor wafer polishing apparatus 11. A polishing cloth 13 is affixed to the surface of the platen 12 that is a rotating disk. On the polishing cloth 13, a carrier 15 that rotatably holds a semiconductor wafer 14 that is a substrate to be polished is mounted. A liquid supply nozzle 16 is disposed above the polishing cloth 13, and a polishing liquid supply device 18 and a pure water supply device 39 are connected to the liquid supply nozzle 16 via a switching device 17. The liquid agents from both supply devices 18 and 19 are supplied onto the polishing cloth 13 as droplets 20 from the liquid agent supply nozzle 16 via the switching device 17 according to the processing steps. The surface of the semiconductor wafer 14 is polished using the polishing apparatus 11 having such a configuration.

  As shown in FIG. 4, the polishing process is performed by a series of steps of start, wafer transfer, polish, water polish, wafer rinse, wafer transfer, and end. Here, in the polishing process, surface polishing is performed in a polishing process using an abrasive liquid containing abrasive grains and a subsequent water polishing process.

  At this time, the pH value variation ΔpH when the pH value of the abrasive liquid is x and the pH value of the water polishing liquid in the water polishing step is y is ΔpH = | xy− ≧ 4. As described above, in the conventional technique, when the polishing process is shifted to the water polishing process, a sudden change in pH value occurs on the polishing cloth.

  FIG. 5 shows an example of equipotential transition and electrical adhesion. As shown in FIG. 5, the isoelectric points of the abrasive grains contained in the abrasive liquid and the polishing substrate interface are often different, and a sudden change in pH value has caused an environment in which both easily adhere to each other. At this time, the abrasive grains electrically attached to the polishing substrate interface became residual dust, which caused a decrease in product yield. Further, since this dust is electrically attached, subsequent cleaning and removal is extremely difficult.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a semiconductor wafer polishing method and a semiconductor wafer polishing apparatus capable of preventing dust adhesion in a semiconductor wafer polishing process.

  In the semiconductor wafer polishing method according to the present invention, the semiconductor wafer is pressed by pressing a semiconductor wafer against a platen on which a rotating polishing cloth is adhered while supplying an abrasive liquid containing abrasive grains and having a first pH value (x). Polishing the semiconductor wafer by pressing the semiconductor wafer against the platen while supplying a chemical solution having a second pH value (y) after the first step of polishing the wafer surface and subsequent to the completion of the first step. The gist of the present invention is that a second step is provided, and the relationship between the first pH value (x) and the second pH value (y) is set to satisfy | x−y | <4.

  According to the present invention, it is possible to prevent dust adhesion in a polishing process of a semiconductor wafer.

  Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a semiconductor wafer polishing apparatus according to the present invention, and FIG. 2 is a process diagram for explaining a semiconductor wafer polishing method according to an embodiment of the present invention. 3 and 5 are denoted by the same reference numerals.

  In FIG. 1, a semiconductor wafer 14 to be polished is placed on a platen 12 to which a polishing cloth 13 is stuck, and various chemicals and the like are dropped from a liquid supply nozzle 16 through a switching device 17. In addition to the abrasive liquid supply device 18 and the pure water supply device 19, a chemical liquid supply device 21 is connected to the switching device 17.

  As a process of the polish part shown in FIG. 2, a polish process is first implemented. As the polishing step, the abrasive liquid is supplied onto the platen 12 from the abrasive liquid supply apparatus 18 of FIG. Thereby, the upper surface of the semiconductor wafer 14 is subjected to predetermined polishing. The pH value of the abrasive liquid used at this time is x.

  After this polishing step, chemical solution polishing is performed. After the supply of the abrasive liquid is stopped, the chemical liquid is supplied onto the platen from the chemical liquid supply device 21 via the switching device 17 to polish the semiconductor wafer 14 with the chemical liquid. The pH value of the chemical solution at this time is y. In this way, the chemical solution polishing step was performed after the polishing step. The relationship between the change amount ΔpH between the pH value x of the polish solution and the pH value y of the chemical solution is such that ΔpH = | xy− <4. The pH values of the polishing liquid and the chemical liquid are set.

  As described above, by setting the relationship between the pH value of the polish solution and the pH solution of the chemical solution in a range in which there is no sudden change in the pH value as described above, a decrease in residual dust was observed. Specifically, as shown in FIG. 6, the dust count value was improved as a result of setting the pH value range according to the present invention to the conventional pH value.

The figure which shows embodiment which concerns on this invention. The figure which shows the process flow of embodiment which concerns on this invention. The figure which shows the conventional semiconductor wafer grinding | polishing apparatus. The figure which shows the process flow of the conventional semiconductor wafer grinding | polishing method. The figure for demonstrating a prior art. The figure for comparing this invention with a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Semiconductor wafer polishing apparatus, 12 ... Platen, 13 ... Polishing cloth, 14 ... Semiconductor wafer, 15 ... Carrier, 16 ... Liquid supply nozzle, 17 ... Switching apparatus, 18 ... Abrasive liquid supply apparatus, 19 ... Pure water supply apparatus, 20 ... droplet, 21 ... chemical supply device.

Claims (3)

  A first step of polishing the surface of the semiconductor wafer by pressing the semiconductor wafer against a platen attached with a rotating polishing cloth while supplying an abrasive liquid having a first pH value (x) containing abrasive grains; A second step of polishing the semiconductor wafer by pressing the semiconductor wafer against the platen while supplying a chemical solution having a second pH value (y) after the completion of the first step; A semiconductor wafer polishing method, wherein a relationship between a value (x) and the second pH value (y) is set to satisfy | x−y | <4.   2. The semiconductor wafer polishing method according to claim 1, wherein the chemical solution is generated by adding a chemical solution for adjusting a pH value.   A platen having a polishing cloth affixed to the surface, a carrier that is installed at a position facing the platen and rotatably holds a semiconductor wafer, an abrasive liquid supply device that supplies an abrasive liquid containing abrasive grains, and the abrasive A chemical supply device that supplies a chemical solution having a pH value that is less than 4 with respect to the pH value of the solution, a pure water supply device that supplies pure water, and a switching device that switches between the supply of the abrasive liquid, the chemical solution, and pure water A semiconductor wafer polishing apparatus comprising:

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