JP2876944B2 - Method and apparatus for evaluating dust generation of wafer main surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for evaluating the dust generation of a wafer main surface made of a semiconductor single crystal, and more particularly, to the manufacture of the wafer, the inspection of a completed wafer product, or the wafer. The present invention relates to a method and apparatus for evaluating the dust generation of a wafer main surface in various processes for manufacturing a semiconductor device using a product.

[0002]

2. Description of the Related Art A typical example of a semiconductor single crystal wafer for manufacturing a semiconductor device is a silicon single crystal wafer. This silicon single crystal wafer (hereinafter simply referred to as a wafer) is chamfered on a disk obtained by slicing in a direction substantially perpendicular to the axis after cylindrical grinding with the pulling axis of the silicon single crystal ingot as a rotation axis, The wafer is manufactured through various processes such as lapping, etching, mirror polishing, cleaning, etc., and the completed wafer is subjected to predetermined inspections, then packaged and packed, and shipped to users who manufacture semiconductor devices. Is put into a complicated line for manufacturing.

[0003] In recent years, however, the degree of integration of semiconductor devices has been increasing, and in order to stabilize the quality and improve the production yield, the management of the process of manufacturing semiconductor devices is becoming stricter. Under these circumstances, dust generation countermeasures, especially in semiconductor device manufacturing lines, are extremely important, and as one of these countermeasures, efforts are being made to eliminate any dust generation due to wafers. . The particle generation due to the wafer is a case where the crystal is pulled up, a case where the particle is derived from a subsequent processing step, or a case where a completed wafer product is contaminated with fine particles. It may cause dust generation. However, in any case, it is a very important task to be able to easily perform a relative evaluation of the state of contamination of the wafer by the fine particles and the dusting property of the wafer in various processes.

[0004]

Conventionally, as a method for evaluating the dusting of a wafer, for example, a sample is immersed in a liquid detergent such as an aqueous hydrofluoric acid solution, and the number of particles desorbed in the detergent is measured. A method and a method of measuring the number of particles detached from a main surface of a sample after a sample is placed in a container and vibrated are known. However, the above-mentioned method has a problem that the operation is troublesome, and the accuracy is poor because an attempt is made to measure the particles which are desorbed and dispersed in the solution.

The present invention has been made in view of the importance of making it possible to easily evaluate the relative dusting of a wafer and the problems of the above-mentioned conventional method. More specifically, it is intended to provide a method and an apparatus for evaluating dust generation, and more specifically, to inspect fine particles present on a wafer main surface which is a flat surface on both sides excluding a chamfered portion of the wafer in the above steps by a simple means. And a device therefor. That is, detachable particles present on the main surface of the sample wafer or dust-generating particles generated by chipping of the main surface of the sample wafer are transferred to the mirror surface of the reference wafer, and the number of the particles is measured. The inventors have found that dust generation on a surface can be relatively evaluated, and have completed the present invention.

[0006]

According to a first aspect of the present invention, there is provided a method for evaluating the dust generation of a wafer main surface comprising a semiconductor single crystal, comprising the steps of: The method is characterized in that a main surface for evaluating dust generation and a mirror surface of a mirror-polished reference wafer are superimposed on each other and pressed to evaluate particles transferred to the mirror surface of the reference wafer.

According to a second aspect of the present invention, there is provided an apparatus for evaluating dust generation on a main surface of a wafer, comprising: a wafer adsorbing member having a plurality of holes to form an adsorbing surface and connecting the holes to a vacuum source; a diaphragm; And a wafer pressing member that connects a supply source of a pressurized fluid to a closed chamber having a press plate at the center of the wafer, the press plate facing the suction surface of the wafer suction member directly in front of the wafer suction member, The wafer can be uniformly pressed by the pressing plate and the suction surface of the wafer suction member by displacing and displacing the diaphragm.

According to a third aspect of the present invention, in the apparatus for evaluating dust generation of a wafer main surface according to the second aspect, the diaphragm is formed of a circular rubber sheet, and the pressing plate is formed of a ceramic or glass disk. And provided concentrically with the diaphragm.

[0009]

According to the method for evaluating dust generation according to claim 1,
Particles adhering or dusting on the sample wafer are detached by overlapping and pressing with the reference wafer and transferred to a mirror-polished surface of the reference wafer (hereinafter, simply referred to as a mirror surface). By observing the particles, the dust-producing particles can be evaluated. In this case, the mirror surface of the reference wafer before and after the superposition / pressing is inspected by, for example, a particle counter, and the number of particles increased by the superposition / pressing is counted. , The number and the like can be measured with high efficiency. Also proceeding one step, the desorbed particles attached to the reference wafer are
It is also possible to analyze the composition of the detached particles by observing with a (scanning electron microscope) and analyzing the energy of fluorescent X-rays generated by irradiating the detached particles with an electron beam.

In the dust generation evaluation apparatus according to the second aspect, for example, the pressing plate of the wafer pressing member and the suction surface of the wafer suction member are respectively opposed to each other with the upper and lower surfaces thereof, and the dust generation evaluation of the sample wafer is performed. The main surface to be performed is placed on the suction surface with the main surface facing upward and fixed by suction, and the two wafers are brought into close contact with the lower part of the pressing member while the reference wafer is placed on the sample wafer with the mirror surface facing downward. When a pressurized fluid is supplied to the closed chamber of the pressing member, the pressing plate descends due to the displacement of the diaphragm, and the sample wafer and the reference wafer are pressed against each other at an equal pressure by being sandwiched between the pressing plate and the suction surface. The dust particles are transferred to the mirror surface of the reference wafer.

In the dust generation evaluation apparatus according to the third aspect, since the diaphragm and the pressing plate are configured as specified, the sample wafer is pressed against the reference wafer with a more uniform pressure than the apparatus according to the second aspect. Therefore, the dust-producing particles of the sample wafer can be transferred evenly to the reference wafer from the entire surface.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the embodiments shown in the drawings. Example 1 A sample wafer and a reference wafer were processed according to the following procedure using the dust generation evaluation apparatus of the present invention shown in FIG. 1, and particles transferred to the pressed surface of the reference wafer were inspected by a particle counter.

First, the structure of the dust generating evaluation apparatus will be described. This apparatus comprises an adsorbing member 11 for adsorbing and fixing wafers and a pressing member 21 for pressing and adhering the wafers. The suction member 11
Is a suction plate 13 formed by forming a large number of intake holes 12 in a circular plate made of ceramic, glass or hard plastic,
Attached to one side of a metal rectangular base 14, the base 14
One end of a nozzle 15 provided in the above is connected to the suction hole 12 and the other end is connected to a vacuum pump (not shown) through a pipe.

The pressing member 21 is formed by forming a closed chamber 31 by a diaphragm 22, a wafer pressing plate 23 provided on one side of the diaphragm, and the like. That is, the diaphragm 22 is a circular sheet made of a flexible material.
The pressing plate 23, which is a disk made of ceramic or glass, is concentrically attached with an adhesive or a fixture, and the outer periphery of the diaphragm 22 is attached to an end of an annular body 27 provided on a rectangular base 26 made of metal. The hermetically sealed chamber 31 is formed by fixing to the portion. Then, one end of a nozzle 32 provided in the closed chamber 31 is communicated with the inside of the closed chamber 31, and the other end is connected to a compressor (not shown) via a pipe.
Further, a rod-shaped (or annular) spacer 41 is inserted between the suction member 11 and the pressing member 21, and these members are detachably attached to the spacer 41 with bolts 42.
The reference wafer Wr and the sample wafer Ws are overlapped and sandwiched between 3 and the pressing plate 23. The diaphragm 22
As the flexible material constituting the material, those conventionally used for diaphragm valves can be applied, and among them, rubber materials are preferable, and the pressure contact between the wafers is more evenly distributed over the entire pressure surface. Can be done with pressure.

Next, the evaluation procedure and results of dust generation according to the present invention will be described. Two mirror-polished wafers obtained by the CZ method were used as sample wafers, and two mirror-polished wafers obtained by the FZ method were used as reference wafers.
The varieties of the wafers used were p-type <100> and 150 mm in diameter. In advance, a particle counter LS is applied to the mirror-polished surface of the reference wafer before the pressing process.
After inspecting with -6000 (HITACHI DECO), the wafer having been inspected was subjected to a pressing treatment according to the following procedure. In using the apparatus of FIG. 1, first, the adsorption member 11 is removed from the apparatus main body, and the sample wafer Ws is placed on the adsorption plate 13 with the main surface on which the dust generation evaluation is performed facing upward, and The sample wafer Ws is adsorbed and fixed by the operation of the vacuum pump. Next, the reference wafer W
r is superimposed on the sample wafer Ws with the mirror side facing down, and the suction member 11 is fixed to the apparatus main body to obtain the state shown in FIG. Then, compressed air is supplied from the compressor as a pressurized fluid, and the wafers Wr are pressed against Ws at a pressure of 1 kgf / cm ² and pressed against each other. Thereafter, the supply of the compressed air is stopped, and the pressure is reduced by a vacuum pump. The pressure plate 23 was detached from the reference wafer Wr, the suction member 11 was removed from the apparatus main body, and the pressed surface (mirror surface) of the obtained reference wafer Wr was inspected by the particle counter.

FIG. 2 shows an inspection result of the reference wafer before the pressing process, and FIG. 3 shows an inspection result of the reference wafer after the pressing process. These figures are images of the wafer displayed on the CRT of the particle counter, and particles having a diameter of 0.1 μm or more are displayed as dots on the images. The value obtained by subtracting the number of particles in FIG. 2 from the number of particles in FIG. 3 indicates the number of dust-producing particles transferred and adhered to the reference wafer by the pressing process. as a result,
The number of dust-producing particles on the main surface of the sample wafer was measured to be 856. As a result of performing the same treatment and inspection as described above using another sample wafer and another reference wafer one by one with the same specifications, the number of dust-producing particles on the back surface of the sample wafer was measured to be 748.

[0017]

As is apparent from the above description, in the dust generation evaluation method according to the first aspect, the dust generation particles on the main surface of the sample wafer are pressed and transferred to the mirror surface of the reference wafer.
Since the mirror surface of the reference wafer is observed before and after the transfer operation, there is an effect that the evaluation of the dust-producing particles can be performed by a simpler operation than the above-described conventional method. Claim 2
According to the dust generation evaluation apparatus described in the above, the sample wafer and the reference wafer are pressed and adhered to each other with uniform pressure due to the displacement of the diaphragm, so that the dust-producing particles of the sample wafer are evenly transferred to the mirror surface of the reference wafer. Can be
Therefore, there is an effect that the evaluation of the dust-producing particles can be performed easily and accurately. According to the dust generation evaluation apparatus of claim 3, the diaphragm is formed of a circular rubber sheet,
Since the pressing plate is formed of a highly flat ceramic or glass disk and provided concentrically with the diaphragm,
Since the sample wafer is pressed against the reference wafer with a more even pressure, there is an effect that the evaluation of the dust-producing particles can be performed more accurately.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an evaluation device according to the present invention.

FIG. 2 shows a result of an example of the present invention, in which particles generated on a mirror-polished surface of a reference wafer before pressing processing are displayed on a CRT of a particle counter.

FIG. 3 shows a result of an example of the present invention, in which particles generated on a mirror-polished surface (pressed surface) of a reference wafer after a pressing process are displayed on a CRT of a particle counter.

DESCRIPTION OF SYMBOLS 11 Suction member 12 Suction hole 13 Suction plate 14 Base 15 Nozzle 21 Press member 22 Diaphragm 23 Press plate 26 Base 27 Annular body 31 Sealed chamber 32 Nozzle 41 Spacer 42 Bolt

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masami Nakano 150 Odakura Osaikura, Nishigo-mura, Nishishirakawa-gun, Fukushima Prefecture Shin-Etsu Semiconductor Co., Ltd. Semiconductor Shirakawa Research Laboratories (56) (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 15/00-15/14 G01N 1/28 G01N 33/00 H01L 21/64-21/66 JICST file (JOIS)

Claims (3)

(57) [Claims] 1. A method for evaluating the dust generation of a main surface of a wafer made of a semiconductor single crystal, wherein a main surface for evaluating the dust generation of a sample wafer and a mirror surface of a mirror-polished reference wafer are mutually separated. A method for evaluating dust generation on a main surface of a wafer, comprising superimposing and pressing, and evaluating particles transferred to a mirror surface of the reference wafer. 2. A wafer suction member having a plurality of holes to form a suction surface and connecting the holes to a vacuum source.
A diaphragm and a wafer pressing member that communicates a supply source of a pressurized fluid to a sealed chamber provided with a pressing plate at the center of the diaphragm, wherein the pressing plate is opposed directly to the suction surface of the wafer suction member, An apparatus for evaluating dust generation on a main surface of a wafer, wherein a wafer is uniformly pressed by a pressing plate and a suction surface of a wafer suction member by supplying a pressurized fluid to displace a diaphragm. 3. The wafer according to claim 2, wherein the diaphragm is formed of a circular rubber sheet, and the pressing plate is formed of a ceramic or glass disk and provided concentrically with the diaphragm. Dust generation evaluation device for main surface.