JP2865056B2 - Apparatus and method for removing particles on substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for manufacturing a semiconductor substrate, a liquid crystal substrate and the like, and more particularly to a method and an apparatus for removing particles attached to the surface of a semiconductor substrate and a liquid crystal substrate.

[0002]

2. Description of the Related Art In the manufacture of semiconductors, if particles larger than the wiring width / interval of a semiconductor element are present, fatal defects for a semiconductor device, such as defective pattern formation and wiring short-circuits, will occur. Therefore, conventionally, in semiconductor manufacturing, wet cleaning using an acid or alkali chemical has been performed for the purpose of removing particles before forming a material film. Generally used is washing with a mixed solution of aqueous ammonia and hydrogen peroxide (hereinafter abbreviated as APM), and its main purpose is to remove inorganic particles and organic particles. This AP
M is for raising the temperature (60 to 80 ° C.) of a liquid obtained by mixing aqueous ammonia, hydrogen peroxide and pure water, and immersing the wafer in the liquid for cleaning. In addition, a cleaning method is known in which organic substances and organic particles are removed by oxidative dissolution using a sulfuric acid-hydrogen peroxide mixture (SPM).

APM cleaning is to remove particles by lifting off particles by slightly etching the surface of the substrate. However, the removed particles are in solution AP
When suspended in M and the substrate is pulled out of solution, particles may reattach to the substrate surface. Particles of 0.2 μm or more that have been targeted for particle contamination up to now
Although a sufficient removal effect was obtained by using washing,
In recent years, finer patterns have been required more and more. For example, a DRAM which is a semiconductor memory is expected to have a pattern width of 0.2 μm or less at a 1-Gbit level of integration. Control of smaller particles is required. However, the behavior of the particles in the solution is determined by the balance between the Coulomb attraction for attracting the particles to the substrate and the repulsive force of the electric double layer generated around the particles and the substrate. Therefore, as the particle size of the particles becomes smaller, the Coulomb attraction becomes larger than the repulsion, and the particles are more easily adsorbed on the substrate. Therefore, in the conventionally used APM cleaning, there is a limit in the ability to remove particles, and sufficient removal of fine particles of 0.2 μm or less cannot be expected.

Further, when cleaning a substrate having a structure in which a metal film such as aluminum or copper is exposed on the surface, a cleaning solution such as APM has a high alkali strength (pH 10 to pH 12). However, the metal film cannot be used because it is significantly etched.

On the other hand, besides the above wet cleaning method,
A removal method that focuses on the charge of particles is also known.

First, Japanese Patent Application Laid-Open No. 2-192110 discloses that
N ionized on the physical wafer_Two Blowing gas
Neutralizes the electrostatic charge of the dust,
Reduces the adhesive force and exhausts the vacuum chamber where the wafer is located.
A method for removing dust by air is described. Only
Particles attached to the substrate are positively charged particles
If there are, there should be particles that are negatively charged.
And various processes for the type of dust that actually occurs.
It is often unpredictable because it has passed. This state
And, for example, N_Two When the gas is charged positively and blown, the negative
Charged particles become electrically neutral, so they are desorbed.
It is possible that
Particles further increase the adsorption power and are difficult to remove. Change
However, even if the charge of the particles is neutralized, the charge is actually
It is extremely difficult to get to zero. It neutralizes particles
To do this, the amount of charge of each particle on the substrate
N _Two Each must be 0 with gas.
Such charge amount control is practically impossible. Therefore,
The removal effect cannot be expected so much with a method such as the known example
it is conceivable that.

Furthermore, in this known example, ionized N2
Gas is blown to blow off particles and exhaust particles neutralized by exhausting the vacuum chamber.However, when the entire chamber in which the wafer is present is evacuated, the ionized gas is sufficiently supplied to the wafer. There is a possibility that the gas is exhausted without contact. Therefore, it is considered that the particles on the wafer cannot be effectively removed by charging, and the effect of removing the particles is not so high.

Japanese Patent Application Laid-Open No. 7-86221 describes a method in which ionized air is blown to alleviate or neutralize the charge of a charged polyimide protective film, and particles are removed by wiping hair. However, even in this method,
As in the above method, it is extremely difficult to neutralize the charge of the protective film by spraying ionized air, and the effect of removing particles cannot be expected. The wiping hair used is considered to be made of a very soft material in order to suppress damage to the substrate surface. However, when wiping the substrate surface directly, there is a high possibility of causing damage.
A substrate in which a device structure is built is particularly problematic in a highly integrated fine structure because it has an extremely delicate surface structure. Further, particles detached from the substrate adhere to the wiping hair, and the particles accumulate on the wiping hair as the treatment is performed. Unless particles adhered to the wiping hair are effectively removed, there is also a problem that the particles are re-adhered to the substrate surface.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and effectively removes even fine particles of 0.2 μm or less without damaging the surface of the substrate. It is an object to provide a method and an apparatus thereof.

[0010]

According to the present invention, there are provided (1) means for holding a substrate on which particles are adhered, (2) means for blowing a charged gas onto the substrate, and (3) particles on a front portion. The present invention relates to a particle removing apparatus having a suction port, an electric dust collecting plate near the suction port, a dust collecting means provided with a vacuum exhaust means at the rear, and (4) a means for charging the electric dust collecting plate.

With this apparatus, a positively or negatively charged gas is blown onto the substrate on which the particles are adhered, so that the particles and the substrate are electrically charged to the same sign. The particles attached to the substrate can be effectively removed by exhausting the particles from the rear while electrically charging the particles with a different sign and bringing the suction port closer to the substrate to attract the particles on the substrate to the electric dust collecting plate.

The step of removing particles will be described with reference to FIG. FIG. 1A shows a state in which negatively charged particles 1 are attached to a positively charged substrate (a wafer or the like) 3. In this state, a charged gas (ionized gas 2) is applied to the surface of the substrate 3 as shown in FIG.
To force the substrate and particles to be positively charged. Since the charged particles 1 have the same positive charge as the substrate 3, a repulsive force acts between the charged particles 1 and the substrate 3, and the particles are easily released from the substrate surface. Then, as shown in FIG. 1C, when the negatively charged electric dust collecting plate 4 is brought close to the substrate 3, the particles 1 are attracted in the direction of the dust collecting plate 4. FIG.
As shown in (D), the particles attracted from the rear part of the dust collecting plate are evacuated to the outside of the device without accumulating the particles in the dust collecting part by vacuum suction.

After removing the particles, preferably FIG.
As shown in (2), by bringing the positively charged substrate 3 into contact with the ground, the charge on the substrate is removed. In this case, to remove the electric charge from the substrate, a gas having a different sign (here, negative) from the substrate may be blown. Thus, the present invention provides
Both the substrate and the particles are positive (or negative) regardless of whether the particles adhering to the substrate are positive or negative, because the ionization gas is used to force the particles and the substrate to be positively (or negatively) charged.
, And the particles are effectively attracted to the electrostatic precipitator having the different sign, so that the particles can be removed more effectively than the conventional method.

Further, the particles are not in contact with the substrate, so that particles can be removed without damaging the surface. Since the removed particles are discharged out of the apparatus, reattachment can be prevented, and high removal performance can be obtained. Further, since no acid or alkali chemicals are used, the semiconductor material film is not etched.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electric dust collecting plate is preferably a grid-like plate. Here, the lattice plate is a plate having a large number of openings (holes), and is not particularly limited as long as the gas containing particles can pass through the openings.

Preferably, the suction port is not sized and shaped to cover the entire surface of the substrate. If the entire surface is covered, the charged gas may be exhausted without coming into contact with the substrate, which is not preferable. For example, a slit-like shape having a slit width of about 以下 or less of the width (or length, diameter, or the like) of the substrate and a width larger than a sufficient width for suction is preferable.

[0017]

Next, the present invention will be described in more detail by way of examples.

One example of the particle removing apparatus according to the present invention is shown in FIG.
As shown in FIG. 2, at least a gas ionizer 11 for charging a gas, a stage 8 having a mechanism for holding a substrate and blowing a charged gas, an electrostatic precipitator 6 for attracting particles, and an electric precipitator for charging the electric precipitator. High voltage power supply 12 for supplying voltage, vacuum pump 13 for evacuating particles
It is composed of

Hereinafter, a case where a wafer is used as a substrate will be described. First, the wafer to which the particles are attached is fixed on a stage. This stage has a mechanism for adsorbing the wafer 3 and also has an outlet 7 for discharging a charged gas (ionized gas 2) toward the center of the wafer. Spraying charges the particles and substrate to the same sign.

In order to produce an ionized gas, the gas is purified by a gas filter 10 and then introduced into a gas ionizer 11. The gas ionizer uses a generally used apparatus. As the gas to be introduced, air may be used, but it is more preferable to use an inert gas such as nitrogen or argon. This is because, since oxygen is contained in the air, a highly oxidizing gas is generated when ionized, which may oxidize the substrate surface.

The flow rate and time for blowing out the ionized gas can be controlled by a microcomputer. It is preferable that the wafer 3 be rotated by the stage rotation mechanism 9 in order to spray the ionized gas evenly on the wafer.

As shown in FIG. 2 and FIG.
Is approached such that the suction port is at a position about 0.1 to 10 mm away from the wafer surface, the particles are attracted and sucked into the electrostatic precipitator from the suction port. The sucked gas is exhausted by the vacuum pump 13. At this time, the high-voltage power supply 12
Supply voltage from It is desirable that the voltage applied to the dust collecting plate be higher than the potential generated in the gas ionization unit 11. This is to effectively attract particles charged by the ionized gas to the dust collecting plate. It is preferable that the suction port has a length longer than the diameter of the wafer and a width of about 5 to 30 mm, and the electric dust collecting plate 4 has a grid shape with the same length and width as the suction port. The reason why the width of the suction port is narrowed in this way is, in part, to secure a high suction force during vacuum suction, but another reason is to effectively remove particles on the wafer. This is for charging. That is, JP
As described in -192110, when the entire chamber in which the wafer is present is evacuated or exhausted, the ionized gas is likely to be exhausted without contacting the wafer. Cannot be effectively charged. On the other hand, in the present invention, by narrowing the frontage of the vacuum suction unit, the ionized gas 2 blown out to the wafer surface is immediately exhausted on the wafer not facing the dust collecting plate 4. In addition, since the particles existing on the wafer can be effectively charged, the removal effect is improved. In addition, since the wafer is rotating, the particles on the entire surface of the wafer can be uniformly and efficiently charged, and the particles can be uniformly removed.

After the particles are removed, the charged wafer is brought into contact with a ground 5 made of a metal piece.
The potential can be returned to zero. The ground 5 removes electric charge from the wafer surface by pressing a metal piece against the surface of the wafer end.

FIG. 4 shows a comparison between the effect of removing particles when the present invention is used and the case where wet cleaning (APM) is used as a conventional example. In the conventional example (APM cleaning), 0.2 μm
Although the following fine particles are difficult to be removed, the method and apparatus for removing particles according to the present invention can effectively remove fine particles of 0.2 μm or less.

Next, the amount of metal etching when the present invention is used is shown in FIG. When an aluminum film is processed using a conventional example (APM cleaning), 1000 minutes in a processing for 10 minutes.
Although the etching is performed in the order of nm or more, the etching amount can be remarkably suppressed by using the removing method according to the present invention.

[0026]

According to the present invention, the particles can be removed without damaging the surface because they are not in contact with the substrate. Since the removed particles are discharged out of the apparatus, reattachment can be prevented, and high removal performance can be obtained. Further, since no acid or alkali chemicals are used, the semiconductor material film is not etched.

According to the present invention, particles and a substrate are forcibly positively (or negatively) charged by using an ionized gas.
Both the substrate and the particles can be positively (or negatively) charged, regardless of whether the particles deposited on the substrate are positive or negative. Therefore, the particles are effectively attracted to the electric dust collecting portion having the different sign, and the particles can be removed more effectively than in the related art.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a mechanism for removing particles according to the present invention.

FIG. 2 is an example of the particle removing device of the present invention.

FIG. 3 is a diagram illustrating an example of the dust collecting means of the present invention.

FIG. 4 is a graph comparing the relationship between the amount of particles remaining on a substrate after processing and the particle size when the present invention and a conventional method are used.

FIG. 5 is a comparison diagram of the etching amount of the aluminum film when the present invention and the conventional method are used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Particle 2 Ionized gas 3 Wafer 4 Electric precipitating plate 5 Ground 6 Electric precipitator 7 Gas outlet 8 Stage 9 Rotary mechanism 10 Gas filter 11 Gas ionizer 12 High voltage power supply 13 Vacuum pump

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/304

Claims (5)

(57) [Claims] A means for holding a substrate to which particles are attached; a means for blowing a charged gas to the substrate; a particle suction port at a front portion; an electric dust collecting plate near the suction port;
A particle removing device comprising: dust collecting means provided with a vacuum exhaust means at a rear portion; and means for charging the electric dust collecting plate. 2. The particle removing device according to claim 1, wherein the electric dust collecting plate is a grid-like plate and covers the suction port. 3. The particle removing device according to claim 1, wherein the width of the suction port is 5 to 30 mm. 4. A positive or negatively charged gas is blown onto a substrate to which particles are attached by using the particle removing apparatus according to claim 1 to electrically connect the particles and the substrate. The dust is charged to the same sign, while the electrostatic precipitating plate is electrically charged to the opposite sign to the particles, and the suction port is brought close to the substrate to exhaust the particles on the substrate to the electric precipitating plate while exhausting from the rear. A method for removing particles, characterized in that: 5. The particle removing method according to claim 4, wherein after the particles are removed, a ground is brought into contact with the charged substrate to return the substrate to zero potential.