JP2005142594A - Method and apparatus for controlling film thickness - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for controlling film thickness capable of sufficiently reducing the amount of dishing and improving the flatness of film in deposition provided on a substrate surface. <P>SOLUTION: A film having a predetermined thickness distribution is formed on the surface of a semiconductor wafer 100 by alternately repeating a film formation process and grinding and polishing process one or more times with respect to the surface of the semiconductor wafer 100. Its apparatus for controlling film thickness is configured by including a susceptor 30 for holding the semiconductor wafer 100; a bath 10 for both film deposition liquid and grinding and polishing liquid in which the semiconductor wafer 100 held by the susceptor 30 is immersed to provide film deposition, grinding, and polishing; and a grinding and polishing pad 20 for grinding and polishing the surface of the semiconductor wafer 100 held by the susceptor 30. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a film thickness adjusting method and apparatus for forming a film on a substrate such as a semiconductor wafer.

  Conventionally, a desired metal is deposited on the surface of a semiconductor wafer via a gas phase or a liquid phase to coat the surface with a metal film. In particular, in order to form the wiring of a semiconductor device, a fine recess (representative width 0.18 μm or less, maximum depth of about 1 μm) is provided in advance on the surface of the semiconductor wafer, and the interior of the recess is filled with no gap. Needed. Moreover, in any case, it is required that the metal surface after film formation be finished with sufficient flatness (represented by irregularities within 2% of the average film thickness).

  Therefore, after film formation, the substrate is usually mounted on a CMP (Chemical Mechanical Polishing) apparatus, and the surface of the film is chemically and mechanically polished to obtain a surface finish condition that satisfies a predetermined required specification.

  However, when a metal for wiring or the like is formed in the insulating film on the surface of the semiconductor wafer and then the surface of the insulating layer is flattened by a CMP operation or the like, as shown in FIG. The problem that the phenomenon (dishing) which is scraped off more than the surface 221 of the surrounding insulating film 220 inevitably occurred.

  There are two reasons for this dishing: (1) the hardness of the metal 210 and the insulating film 220 is different, and (2) the corrosion rate of the metal 210 and the insulating film 220 with respect to the grinding / polishing liquid is different. Conceivable.

  In order to avoid these causes (1) and (2), conventionally, the sliding speed and surface pressure during grinding and polishing by CMP have been reduced, and a corrosion inhibitor has been mixed into the grinding and polishing liquid. However, it is difficult to obtain a complete effect, and there is also a problem in that the improvement in throughput is hindered due to a decrease in the grinding / polishing speed.

  The present invention has been made in view of the above points, and its purpose is to provide a film thickness adjusting method capable of sufficiently reducing the dishing amount and improving the flatness of the film provided on the substrate surface, and To provide an apparatus.

The invention according to claim 1 of the present application is a film thickness adjusting method for forming a film having a predetermined thickness distribution on a substrate surface, wherein the film thickness adjusting method is a method for forming a film on a substrate surface by electrolytic plating. The film thickness adjusting method is characterized by comprising a film process and an electrolytic processing process of grinding and polishing the film by electrolytically processing the substrate after the electrolytic plating.
The invention according to claim 2 of the present application resides in the film thickness adjusting method according to claim 1, wherein in the electrolytic processing step, mechanical grinding / polishing is also performed in combination with the electrolytic processing.
Invention of Claim 3 of this application exists in the film thickness adjustment method of Claim 1 or 2 characterized by performing the said film-forming process and the said electrolytic processing process in the same tank.
The invention according to claim 4 of the present application is the film thickness adjusting method according to claim 1, wherein the substrate after the electrolytic processing is returned to the film forming step or the electrolytic processing step again.
The invention according to claim 5 is the film thickness adjusting method according to claim 1 or 2, wherein the film forming step and the electrolytic processing step are performed in separate tanks.
Invention of Claim 6 of this application repeats the said film-forming process and the said electrolytic processing process 1 time or more alternately with respect to the base material after the said electrolytic processing, The film thickness adjustment of Claim 1 characterized by the above-mentioned Is in the way.
The invention according to claim 7 of the present application is a film thickness adjusting method for forming a film having a predetermined thickness distribution on the substrate surface, wherein the film thickness adjusting method is a method for forming a film on the substrate surface by electrolytic plating. From a film process, an electrolytic processing process of electrolytically processing the base material after electrolytic plating and grinding / polishing the film, and a step of determining whether to return the base material after electrolytic processing back to the film forming process The film thickness adjusting method is characterized by the following.
The invention according to claim 8 of the present application is a film thickness adjusting apparatus for forming a film having a predetermined thickness distribution on the surface of the substrate, wherein the film thickness adjusting apparatus supplies a film forming solution for electrolytically plating the substrate. And a switch for switching the polarity of the voltage of the power supply for electrolytic plating in order to perform electrolytic processing on the substrate after electrolytic plating.
The invention according to claim 9 of the present application is a film thickness adjusting apparatus for forming a film having a predetermined thickness distribution on the surface of a substrate, wherein the film thickness adjusting apparatus supplies a film forming solution for electrolytic plating of the substrate. The film thickness adjusting apparatus includes means and a power source for electrolytic plating, and a tank for performing electrolytic plating and electrolytic processing on the base material.
The invention according to claim 10 of the present application is a film thickness adjusting apparatus for forming a film having a predetermined thickness distribution on the surface of the substrate, wherein the film thickness adjusting apparatus includes a tank and a film formation for electrolytic plating of the substrate. The film thickness adjusting apparatus includes a liquid supply unit, a power source for electrolytic plating, and a tank for performing electrolytic processing on a substrate after electrolytic plating.
The invention described in claim 11 of the present application has a film thickness meter for measuring the surface of the substrate after the electrolytic processing and determining whether or not to perform electrolytic plating again on the substrate. 8 or 9 or 10 in the film thickness adjusting device.
The invention according to claim 12 of the present application is the film thickness adjusting apparatus according to claim 8, 9 or 10, wherein mechanical grinding / polishing is performed in combination with the electrolytic processing.
The invention according to claim 13 of the present application is the film thickness adjusting apparatus according to claim 11, wherein the film thickness meter measures the dishing amount of the measured substrate surface.

According to the present invention, film formation by electrolytic plating and grinding / polishing by electrolytic processing are alternately repeated, so that the amount of dishing can be made sufficiently small and the film provided on the substrate surface It has an excellent effect that the flatness of the film can be improved. The present invention is particularly suitable for use in forming a metal wiring portion of a semiconductor wafer.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an overall schematic configuration diagram showing one configuration example of a film thickness adjusting device. In this configuration example, for the sake of explanation, mechanical grinding / polishing is mainly used as the grinding / polishing process. However, the present invention uses at least electrolytic processing as the grinding / polishing process as described below. Is. As shown in the figure, this apparatus is installed in a tank 10 that serves both as a film forming liquid tank and a grinding / polishing liquid tank, a grinding / polishing table 20 installed in the tank 10, and a tank 10 that is freely accessible. Susceptor 30, film forming solution supplying means 40 for supplying a film forming solution into the tank 10, grinding / polishing solution supplying means 50 for supplying a grinding / polishing solution into the tank 10, a film thickness meter 60, electrolysis And an electric circuit for plating 70. Each component will be described below.

  The grinding / polishing table 20 has a mechanical grinding / polishing surface 21 on its surface and is configured to be rotationally driven by a rotating shaft 23.

  The susceptor 30 holds the semiconductor wafer 100 on its lower surface, and its rotation shaft 31 is configured to be movable up and down and to the left and right and to be rotatable.

  The film formation liquid supply means 40 includes a film formation liquid reservoir 41, a temperature controller 43, and a liquid quality monitor / adjustment device 45, and the grinding / polishing liquid supply means 50 includes a grinding / polishing liquid reservoir 51 and a temperature controller 53. And a liquid quality monitor / adjustment device 55, both of which are connected to one pipe 80 via four valves 47, 49, 57, 59. A pump 83 and a filter 85 are attached to the pipe 80.

  The film thickness meter 60 is configured to be movable up and down, left and right, and back and forth, and the tip thereof is a film thickness measuring unit 61.

  The electroplating electric circuit 70 includes a power source 71 and is connected so that the semiconductor wafer 100 serves as a cathode and the counter electrode 73 serves as an anode. A switch 75 switches the polarity of the voltage supplied to the counter electrode 73 and the semiconductor wafer 100.

  Next, the operation of this apparatus will be described with reference to FIGS. 1, 2, and 3. First, as shown in FIG. 1, a semiconductor wafer 100 with a surface to be deposited is placed on the lower surface of the susceptor 30. (Step 1), the susceptor 30 is lowered to the position indicated by the solid line in FIG. Note that the surface of the semiconductor wafer 100 to be formed is formed on the surface of the insulating layer 103 as shown in FIG. 3A with a number of fine recesses (holes and holes) having a width of 500 to 1 μm. Groove) 105 is provided.

Next, the pump 83 is driven, the valves 47 and 49 are opened, the film forming solution is introduced into the tank 10 to fill it (Step 2), and film formation is executed (Step 3). That to facilities electroplating a semiconductor wafer 100 surface by turning on the electrolytic plating electric circuit 70 (of copper alloy and / or nickel alloy composed mainly of copper or copper in this embodiment) in this embodiment. For the purpose of such film in the film thickness distribution uniform, it rotates the semiconductor wafer 100 by rotating the susceptor 30 as needed.

  After the film formation on the surface of the semiconductor wafer 100 is completed, the film forming liquid is returned to the film forming liquid reservoir 41, the valves 47 and 49 are closed and the valves 57 and 59 are opened, and the grinding and polishing liquid reservoir 51 is ground and polished by the pump 83. The tank 10 is filled with the liquid (Step 4).

  Then, the susceptor 60 is lowered and brought into contact with the mechanical grinding / polishing surface 21, the grinding / polishing table 20 and the susceptor 30 are simultaneously rotated at different rotational speeds, and both are reciprocated as necessary. The surface of the semiconductor wafer 100 is uniformly ground and polished (step 5).

  At this time, as shown in FIG. 3B, dishing occurs on the surface 101 a of the wiring metal part 101 embedded in the fine depression 105.

  Next, the susceptor 30 is raised and pulled up from the grinding / polishing liquid, the film thickness measuring unit 61 of the film thickness meter 60 is applied to the surface 101a of the metal part 101 of the semiconductor wafer 100, and the dishing amount is measured by scanning in the lateral direction. (Step 6).

  If the dishing amount measured in step 7 is less than or equal to the preset allowable value, the operation is ended. If the measured dishing amount is excessively cut from the allowable value, the process returns to step 2 and again. A plating film forming process and a subsequent grinding / polishing process are performed. The amount of film formation in the next re-deposition process is determined according to the measured dishing amount, and the grinding / polishing amount is also adjusted.

  That is, as shown in FIG. 3C, after a predetermined amount of film is formed on the metal part 101, the surface is ground and polished again by the grinding and polishing process as shown in FIG. Adjust so that the amount is small.

  On the other hand, when the dishing amount measured in step 7 is negative, that is, as shown in FIG. 3E, the surface 101a of the metal part 101 protrudes from the periphery, the process returns to step 4 and the grinding / polishing process is performed again. To do. At that time, the grinding / polishing amount is adjusted according to the measured dishing amount.

  That is, according to the present invention, when the dishing amount does not fall within the allowable value, the process returns to the film forming process and the grinding / polishing process again, so that the dishing amount finally falls within the allowable value. .

In the above configuration example , mechanical grinding / polishing is used as the grinding / polishing method, but electrolytic machining is used in the present invention. Also in this electrolytic processing, the other example, just chemical machining, one of the machine械的grinding and polishing process or those they combine multiple use.

  As usual, chemical processing uses a solution of nitric acid, hydrochloric acid, sulfuric acid, hydrofluoric acid, etc., and the metal is eluted from the surface to cut to the desired film thickness. Adjust by concentration, temperature, supply flow rate, etc.

  In electrochemical machining, the base material is connected to the anode and the counter electrode is set to the cathode (reverse polarity in the case of electrolytic plating), mainly in an acid solution as a grinding fluid, causing electrochemical elution from the base material side. Grind and polish with In other words, in the apparatus shown in FIG.

  In any case, the substrate can be rotated as necessary.

  In the case of mechanical grinding / polishing, the working fluid is an acid, alkali, or neutral aqueous solution in which abrasive grains are suspended, and the susceptor 30 and the grinding / polishing table 20 are pressed against each other at a desired surface pressure, either or both. Is relatively rotated and translated so that the relative slip amount with respect to the grinding / polishing table 20 is made uniform within the surface of the substrate (semiconductor wafer 100).

  As described above, an arbitrary grinding / polishing situation can be realized by combining chemical, electrochemical, mechanical grinding and polishing operations individually or in combination.

In the configuration example of FIG. 1, film formation and grinding / polishing are performed in the same tank 10 as an example. However, film formation, grinding and polishing may be performed in separate tanks, or grinding / polishing. Of these, chemical / electrochemical processing and mechanical grinding / polishing may be performed in separate tanks.

  By the way, since various combinations of the actual base material and the metal material to be formed are generally considered, it is necessary to select various methods for the grinding / polishing method according to the combination.

  As a general feature, according to chemical / electrochemical processing, the processing speed is slow, but damage to the surface to be processed is small, and so-called work-affected layers do not occur. On the other hand, mechanical processing has a high processing speed, but scratches are formed on the surface to be processed, and mechanical damage due to abrasive grains and loss of some deposited metal are likely to occur. Invite.

  When measuring the dishing amount in step 6 of FIG. 2, a film thickness meter of a mechanism other than the contact-type film thickness meter 60 shown in FIG. 1 may be used, and the substrate is removed from the apparatus for surface shape inspection. You can do this by moving to another device. The surface shape inspection may be performed visually.

  Generally, it is considered necessary to use a plurality of film forming liquids and grinding / polishing liquids depending on the types of film materials and film forming / processing methods. In that case, the number of the film formation liquid reservoir 41 and the grinding / polishing liquid reservoir 51 shown in FIG. 1 increases.

  Further, in the film thickness adjusting apparatus shown in FIG. 1, all film formation / processing is performed in a single tank 10, but each process may be shared by a plurality of tanks. In that case, the number of tanks naturally increases from the case shown in FIG.

It is a whole schematic block diagram which shows the example of 1 structure of a film thickness adjusting apparatus. It is an operation | movement flowchart which shows an example of operation | movement of a film thickness adjusting apparatus. 3 is an enlarged cross-sectional view of a main part showing a film formation / filling state on the surface of a semiconductor wafer 100. FIG. 3 is an enlarged cross-sectional view of a main part showing a film formation / filling state on the surface of a semiconductor wafer 100. FIG.

Explanation of symbols

10 tanks (combined with film forming liquid tank and grinding / polishing liquid tank)
20 Grinding / polishing table 30 Susceptor 40 Film forming solution supply means 50 Grinding / polishing solution supplying means 60 Film thickness meter 100 Semiconductor wafer (base material)
105 Fine depression

Claims (7)

  A film having a predetermined thickness distribution is formed on the surface of the base material by alternately repeating the film forming process and the grinding / polishing process one or more times on the surface of the base material. To adjust the film thickness.   2. A fine recess having a width of 500 to 1 [mu] m is processed in advance on the surface of the base material, and a film material is filled in the fine recess by the film forming step. Described film thickness adjustment method.   3. The film thickness adjusting method according to claim 1, wherein the film is formed by electrolytic plating or electroless plating.   4. The film thickness adjusting method according to claim 1, wherein the base material is a semiconductor wafer, and the film material is copper or a copper alloy and / or a nickel alloy containing copper as a main component.   The film grinding / polishing is performed by chemical processing, electrolytic processing, mechanical grinding / polishing, or a combination of any two or all of them. 4. The film thickness adjusting method according to 4. At least a susceptor holding the substrate;
A film forming solution tank for immersing the substrate held in the susceptor to form a film;
A film thickness comprising: a grinding / polishing liquid tank for grinding / polishing the surface of the substrate by abutting the surface of the substrate against a grinding / polishing table installed inside by immersing the substrate held in the susceptor Adjustment device.   7. The film forming liquid tank and the grinding / polishing liquid tank are configured by attaching a film forming liquid supply means and a grinding / polishing liquid supply means in the same tank. Film thickness adjustment device.

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