JPH07105369B2 - Wafer polishing method and polishing apparatus - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for polishing a wafer, and more particularly to a semiconductor manufacturing process and apparatus for polishing a wafer or planarizing a substrate having an uneven surface. is there.

Conventional technology With the ultra miniaturization of ULSI in recent years, in order to form a reliable wiring with the fine wiring processing technology in multilayer wiring,
A flatter base shape is required. Generally, 2
The SOG (spin-on-glass) coating method and the resist etch back method are used in the flattening process of the insulating film after the layer, but these methods have many drawbacks. The SOG coating method has a problem that the film quality of SOG itself is weak in water resistance and does not become completely flat, and the resist etch back method has problems such as complicated process and low throughput. As one means for solving this problem, there is a polishing method in which a wafer is directly cut for flattening.

Problems to be Solved by the Invention Although polishing techniques have actually existed in the past, there has been a problem that it is extremely difficult to process with an accuracy higher than 1 μm, which is required in the flattening step of the insulating film. In view of the above problems, it is an object of the present invention to provide a wafer polishing method and a polishing apparatus capable of precisely, rapidly and easily completely flattening a substrate having irregularities.

Means for Solving the Problems The present invention, in order to solve the above problems, a step of spin-coating an organic resist or silica glass containing a specific element, a specific dye or a specific chemical substance on a substrate having irregularities, and A step of bringing the surface of the substrate into close contact with a surface of a polishing device and polishing with a polishing liquid, and a step of analyzing polishing effluent to detect or analyze the elements, dyes, and chemical substances. A method of polishing a wafer, which comprises determining a polishing end point, and controlling a rotation speed, a load pressure, and a load position of the polisher.

Further, the present invention comprises a polishing table, a wafer polishing rotator facing the wafer polishing table, and noise for applying a polishing solution to the surface of the wafer polishing table, and the main body is configured to detect a polishing waste solution and analyze it. And a function for applying pressure unevenly at the contact points of the wafer polishing rotator and wafer polishing table, and detecting the polishing waste liquid, and adjusting the pressure depending on the concentration of the element, dye or chemical substance. ，
The wafer polishing apparatus is characterized in that the wafer is polished by feeding back the rotational speed, load pressure, and load position of the wafer polisher.

Action With the above polishing method and polishing apparatus, the complete flattening of the ULSI surface having irregularities can be performed accurately, at high speed, and easily.

Embodiments (Embodiment 1) The present invention will be described based on embodiments with reference to the drawings. First, a schematic view of the apparatus used in the present invention will be shown. FIG. 1 shows a block diagram of the polishing system of the present invention. 10 is a polishing rotator having a rotating mechanism, 11 is a polishing table on which a substrate (sample) can be placed, and the main body is mainly 2
It is composed of two. Further, the polishing waste liquid can be collected from the lower portion of the polishing table 11 and can be analyzed by the waste liquid detecting device 12. Further, as a feature of this device, the electric signal of the output of the waste liquid detection device 12 can be fed back to the polishing rotator 10, and the polishing rotator 10 can be braked and rotated by detecting the concentration of a specific substance contained in the waste liquid. The speed, weight, and weight position can be changed freely.

FIG. 2 is a perspective view of the polishing table body. 6 to the polishing table 11
The 8-inch substrate 13 can be installed by suction. Polishing table 11
There is a polishing rotary machine 10 parallel to the polishing table 11 at the top of the
It is fixed so that the upper surface of 13 can be fitted accurately. Further, the upper surface of the polishing table 11 is provided with a nozzle 14 capable of jetting a predetermined amount of polishing liquid, so that various polishing liquids can be flowed.

The polishing rotator 12 has a precise rotation mechanism and can apply a load to four directions A, B, C and D shown in FIG. FIG. 3 shows how this weight is applied. The figure shows the surface of the 6-inch wafer 13, and it is possible to apply an arbitrary fixed amount of load to the four points A, B, C, and D, and electrically control the unevenness of shaving.

(Example 2) As Example 2 of the present invention, a process of actually flattening a substrate surface having an uneven surface will be described. In particular, this embodiment shows an example in which the planarization process is applied to the interlayer insulating film. The process of flattening will be described step by step with reference to FIG.

In the same figure (a), a thermal oxide film 42 is formed on a 6-inch Si substrate 41,
Al wiring (Al film thickness 0.8 μm) 43 is formed by using photolithography and dry etching technology, and TESO (tetraethoxysilane) is formed by plasma CVD as an interlayer insulating film.
SiO 2 film 44 is deposited by 2.4 μm. In this state, A
As much as the thickness of the L wiring 43, irregularities are formed on the SiO 2 film 44. In FIG. 6B, a dummy resist 45 for flattening is spin-coated in addition to the above structure. This resist contains a dye (diazo compound) for detecting the end point and controlling the rotary polisher.

The figure (c) shows a process diagram of polishing, and the figure (d) shows the final state where the planarization is completed.

FIG. 5 shows details of the process in which the polishing process is performed. FIG. 5 (a) shows the concentration of the specific dye (here, diazo compound) in the polishing waste liquid, and FIG. 5 (b) shows the magnitude of the load of the rotary polisher. Each horizontal axis shows the current load. Points (A, B, C, D), that is, the time axis. In this embodiment, it is programmed that loads are applied in order around the points A, B, C and D (see the mountain in FIG. 3).

First, only the polishing resist 45 is scraped off so that a load is evenly applied to the polishing rotator 10. When the surface of the SiO2 film 44 comes out (see FIG. 4 (c)), the proportion of the resist 45 to be scraped decreases, so that the dye detected in the resist sharply decreases (shown by (a) in the figure). ). At this stage, the size of the load is reduced and the load is evenly applied, and the load is displaced. At this time A, B, C,
The time for applying a load to D is 30 seconds, and the amount of the dye in the polishing waste liquid flowing during 30 seconds is quantified (indicated by (B) in the figure). This quantified result is fed back to the magnitude of the load applied to A, B, C, and D for the second time, and programming is performed so that the load is increased as the concentration of the dye increases. If this operation is continued until no dye is detected in the polishing waste liquid, a completely flat surface is achieved. This state is shown in FIG. 4 (d).

Of course, it is also possible to mix an HF-based etching solution in the polishing agent, and instead of the organic resist applied to the substrate, spin-coat silica glass containing a specific element, a specific dye or a specific chemical substance. It goes without saying that it is okay. Furthermore, this technique has a wide range of applications as a flattening method for substrates, trenches and the like.

EFFECTS OF THE INVENTION As is clear from the above description, according to the present invention, 1. Complete flattening is possible. 2. The process is extremely simple. 3. Since plasma is not used, there is no damage of load particles. Four.
Since the etching amount is large, the processing speed is high (throughput is improved). 5. Flattening is possible without depending on the mask for patterning or the underlying shape.

[Brief description of drawings]

FIG. 1 is a block diagram of a polishing system, FIG. 2 is a perspective view of a polisher main body, FIG. 3 is a surface view of a 6-inch wafer, FIG. 4 is a process diagram in which flattening is performed, and FIG. It is a detailed view of a process performed. 10 …… polishing rotator, 11 …… polishing table, 12 …… waste liquid detector, 13 …… substrate, 14 …… nozzle, 41 …… 6 inch substrate,
42 …… thermal oxide film, 43 …… AL wiring, 44 …… SiO2 film, 45 ……
Resist.

Claims (2)

[Claims] 1. A step of spin-coating an organic resist or silica glass containing a specific element, a specific dye or a specific chemical substance on a substrate having irregularities, and bringing the surface of the substrate into close contact with the surface of a polisher to obtain a polishing liquid. And a step of polishing with
And a step of detecting or analyzing the element, dye, or chemical substance by analyzing a polishing effluent, wherein the rotation speed, load pressure, and load position of the polisher are controlled by the detection and analysis. Wafer polishing method. 2. A wafer polishing table, a wafer polishing rotator installed so as to face the wafer polishing table, a means for supplying a polishing solution onto the wafer polishing table, and a polishing waste solution after polishing, A means for analyzing and a means for applying pressure non-uniformly at the contact point between the wafer rotator and the wafer polishing table, the rotation speed of the wafer polishing machine based on the detection of the polishing waste liquid and the analysis result. A wafer polishing apparatus characterized by controlling a load pressure, a load position and a load position.