JPH08124885A - Semiconductor substrate grinder - Google Patents

Abstract

PURPOSE: To prevent dielectric breakdown of an insulating film by a method wherein, when a surface of a semiconductor substrate is ground to flatten, ionized gas having a different mark from charged static electricity is supplied to the semiconductor substrate and the static electricity generated in the semiconductor substrate is neutralized. CONSTITUTION: An abrasive is supplied from an abrasive supply nozzle 9. Further, almost simultaneously, ionized gas is sprayed from an ionized gas supply part 11. As the ionized gas is sprayed to a portion where a table surface 1A comes into contact with a surface of a semiconductor substrate 6, static electricity generated by grinding is neutralized while ground. Under this state, the surface of the semiconductor substrate 6 is ground.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate polishing apparatus.

[0002]

2. Description of the Related Art In recent years, a CMP apparatus has been used as a semiconductor substrate polishing apparatus for flattening the surface of a semiconductor substrate.
This CMP apparatus is an apparatus for contacting the surface of a rotating table while rotating the semiconductor substrate and polishing the surface of the semiconductor substrate with an abrasive.

[0003]

The case of polishing an insulating film formed above a MOS transistor by the above-described CMP apparatus will be schematically described. That is, as shown in FIG.
The semiconductor substrate 23 is brought into contact with each other, and the polishing agent 24 is poured into the contact surface and polished. In the semiconductor substrate 23, MOS is formed in a region partitioned by the field oxide film 25.
The transistor 26 is formed. This MOS transistor 26 has diffusion layers 27, 27 serving as a source / drain.
The gate oxide film 28 is formed above the channel region between them, and the gate electrode 29 is formed above the gate oxide film 28. Further, an insulating film 30 is formed so as to cover the MOS transistor 26.

When the insulating film 30 is mechanically polished by a CMP apparatus, the surface of the substrate is negatively charged by static electricity generated during polishing, and in particular, the gate oxide film 28 is deteriorated and leaks by electrostatic discharge. Occurs, and the product yield is reduced.

The present invention has been made in view of the above,
An object of the present invention is to provide a semiconductor substrate polishing apparatus capable of neutralizing static electricity generated when polishing the surface of a semiconductor substrate without lowering the polishing effect and preventing electrostatic breakdown of an insulating film or the like formed on the semiconductor substrate. To do.

[0006]

According to the present invention, the surface of a semiconductor substrate is brought into contact with the surface of a rotary table for flattening the surface of the semiconductor substrate while rotating the surface of the semiconductor substrate, and an abrasive is injected to the surface of the semiconductor substrate. In a semiconductor substrate polishing apparatus for polishing, an ionized gas supply means for supplying an ionized gas having a sign different from that of static electricity to the semiconductor substrate in order to neutralize static electricity generated in the semiconductor substrate when polishing the semiconductor substrate. It is configured to have.

[0007]

When the surface of the semiconductor substrate is polished for flattening, ionized gas having a sign different from that of the charged static electricity is supplied to the semiconductor substrate to neutralize the static electricity generated in the semiconductor substrate. Therefore, electrostatic breakdown of the insulating film can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a semiconductor substrate polishing apparatus according to the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, this apparatus has a circular rotary table 1 for polishing. The table 1 has a table surface 1A which serves as a reference surface for polishing, and is attached to the rotary shaft 2 on the opposite side of the table surface 1A. A pulley 4 is attached to the motor 3 for rotating the table, and a belt 5 is stretched between the rotary shaft 2 and the pulley 4. A contact / separation mechanism 7 for contacting / separating the semiconductor substrate 6 with respect to the table surface 1A is provided above the table 1. The contact / separation mechanism 7 has a fixing ring 7a for fixing the semiconductor substrate 6, and the fixing ring 7a has a rotating shaft 7b.
It is attached to the motor 7c for rotating the semiconductor substrate via. The semiconductor substrate 6 is sequentially transported by the transport device 8. Further, a polishing agent supply nozzle 9 for supplying a polishing agent on the table surface 1A during polishing is arranged.
As the abrasive, for example, colloidal silica (silicon dioxide SiO ₂ ) is used, but colloidal silica to which an additive is added may be used. The polishing agent supply nozzle 9 supplies a polishing agent whose flow rate is adjusted during polishing, and pure water is supplied by a switching valve 10 after completion of polishing.

Further, an ionized gas supply unit 11 is provided so that the ionized gas can be injected onto the semiconductor substrate 6 on the table 1.
Is provided. As shown in FIG. 3, a discharge electrode 11b is inserted in an insulating manner into a nozzle (blowout port diameter 3 to 10 mm) 11a of the ionized gas supply unit 11. A high voltage is applied to the discharge electrode 11b from the power supply section 12 to cause discharge from the discharge electrode 11b, and the nozzle 1
The gas passing through the inside of 1a is ionized. The gas used here may be air or an inert gas (nitrogen gas, helium, neon, argon gas, etc.), that is, a gas that does not chemically react with the polishing agent. These gases become positive ions by discharge and are sprayed onto the semiconductor substrate 6 which is negatively charged by static electricity.

A case where a semiconductor substrate is polished by the above apparatus will be described. First, the table 1 is rotated by the motor 3 in the direction of the arrow. The semiconductor substrate 6 is transferred from the transfer device 8 and adsorbed and fixed to the fixing ring 7 a of the contact / separation mechanism 7. The semiconductor substrate 6 is brought into contact with the table surface 1A while being rotated by the motor 7c. At this time, the polishing agent is supplied from the polishing agent supply nozzle 9, and the ionized gas is jetted from the ionized gas supply unit 11 almost at the same time. Since the ionized gas is jetted to the contact portion between the table surface 1A and the surface of the semiconductor substrate 6, the polishing is performed while neutralizing the static electricity generated by the polishing. In this state, the surface of the semiconductor substrate 6 is polished.

The amount of static charge on the semiconductor substrate after being polished in this way is shown below in comparison with the conventional example. That is, when the semiconductor substrate covered with the oxide film (insulating film) of 10000 angstrom is subjected to the planarization process, the potential of the substrate surface is − in the conventional example.
It was charged to 3000V to -4000V. On the other hand, in this example, the potential of the substrate surface was ± 0V.
From this, it is understood that the static electricity of the semiconductor substrate is almost removed. The flattening effect of the conventional example and that of the present example were substantially the same. Next, with respect to electrostatic breakdown, as a result of measuring the withstand voltage of the withstand voltage evaluation sample, the yield was 75% in the conventional example, but in the present example, the yield was improved to 90%.

According to the embodiment of the present invention, when a semiconductor substrate is polished, the ionization gas for neutralizing static electricity is jetted, so that the static electricity generated on the substrate is neutralized and polished. Therefore, it is possible to prevent a decrease in product yield due to electrostatic breakdown. Further, since the apparatus of the present invention only injects the ionized gas onto the semiconductor substrate, it is possible to suppress the adverse effect on the surface flattening processing effect (polishing effect) as much as possible. For example, by using an inert gas as the ionized gas, it is possible to prevent the chemical reaction with the polishing agent.

It should be noted that the concrete examples of the polishing agent in the examples are merely examples, and the polishing agent is not limited thereto.

[0014]

According to the present invention, since the polishing is performed while neutralizing the static electricity generated on the substrate, the semiconductor substrate can be prevented from being charged, and the insulating film formed on the semiconductor substrate can be prevented. Electrostatic breakdown can be suppressed as much as possible.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention.

FIG. 2 is a perspective view of a main part of the apparatus shown in FIG.

FIG. 3 is a vertical cross-sectional view of an ionized gas supply unit.

FIG. 4 is an explanatory diagram for explaining how the semiconductor substrate is polished.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotary table 2 rotary shaft 3 motor 4 pulley 5 belt 6 semiconductor substrate 7 contact / separation mechanism 7a fixed ring 7b rotary shaft 7c motor 8 transfer device 9 abrasive supply nozzle 10 switching valve 11 ionized gas supply unit 11a nozzle 11b discharge electrode 12 power supply Department

Claims (3)

[Claims] 1. A semiconductor substrate polishing apparatus for polishing a surface of a semiconductor substrate by bringing the surface of the semiconductor substrate into contact with the surface of a rotary table for flattening the surface of the semiconductor substrate while rotating the surface and injecting an abrasive. A semiconductor substrate comprising an ionized gas supply means for supplying an ionized gas having a sign different from that of the static electricity to the semiconductor substrate in order to neutralize the static electricity generated in the semiconductor substrate when polishing the semiconductor substrate. Polishing equipment. 2. The semiconductor substrate polishing apparatus according to claim 1, wherein the ionized gas supply means is configured to inject gas ionized by discharge to the semiconductor substrate. 3. The semiconductor substrate polishing apparatus according to claim 2, wherein the polishing agent is a solution containing colloidal silica as a main component, and the gas is air or an inert gas.