JPH10172944A - Method for cleaning rear face of wafer in photolithographic step of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent chemicals and pure water from creeping into the inside of nozzles even at the time of low speed rotation irrespective of the wafer size by a construction such that a plurality (at least four) of cleaning nozzles are arranged at equal intervals in a rotating mechanism. SOLUTION: A wafer 1 is held on a wafer chuck 2 by vacuum suction. A plurality of wafer rear face cleaning nozzles 4 are disposed from a rotating mechanism and the wafer chuck 2. The rear face cleaning nozzles 4 are arranged closely to the wafer chuck 2 as much as possible and non-cleaning nozzles 4 has a structure of being arranged closely to the wafer chuck 2 as much as possible, thereby reducing the non-cleaning area. The rear face cleaning nozzle 4 provided for the rotating mechanism have a construction such that a plurality of (at least four) cleaning nozzles are arranged at equal intervals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resist coating process used in a photolithography process of a semiconductor device,
Alternatively, the present invention relates to a wafer back surface cleaning method in a photolithography process of a semiconductor device used for wafer back surface cleaning performed during a development process.

[0002]

2. Description of the Related Art In a conventional method, in a resist coating process in a photolithography process or a back surface cleaning in a developing process, a cleaning nozzle fixed to a unit is used and vacuum suction is performed on a wafer chuck. The cleaning is performed by discharging a chemical solution or pure water from the cleaning nozzle while rotating the wafer held.

The cleaning nozzle varies depending on various conditions such as a wafer size, a discharge nozzle diameter, a discharge pressure, a distance between the nozzle tip and the wafer, and is generally a single nozzle or an inner peripheral portion and an outer peripheral portion. The structure provided in two places of the part is adopted.

FIG. 5 shows a cross-sectional structure in which a cleaning nozzle 104 is provided on the inner and outer peripheral portions, and FIG. 6 shows a structural diagram as viewed from above the structure.

In FIG. 5, a centered wafer 101 is arranged on a wafer chuck 102, and the wafer 101 is held by vacuum suction.

Next, the wafer 101 is rotated at an arbitrary number of revolutions, and a wafer surface treatment is performed by discharging a resist in the case of resist coating and discharging a developing solution in the case of developing processing. You. Subsequently, after the formation of a predetermined resist film thickness or the completion of the development process, the back surface cleaning nozzle 10
From 4 on, the wafer back surface cleaning is performed by discharging an organic solvent in the case of resist coating and discharging pure water in the case of development processing.

[0007] Generally, the processing is performed on the basis of the number of revolutions at the time of the back surface cleaning set to 1000 rpm / min or less.

[0008] Next, after the wafer back surface cleaning, the removal process is performed by applying a centrifugal force by applying a rotation process at 2000 rpm / min or more for the purpose of removing the organic solvent or pure water remaining on the wafer back surface. Apply.

[0009]

In recent semiconductor devices, the size reduction of semiconductor elements has been steadily miniaturized year by year, and element formation in a submicron area which is less than half a micron from the base has become common. It is coming.

In addition to the miniaturization of the element formation dimensions, especially in memory products such as DRAMs, the chip size is inevitably increased as the memory capacity is increased.

[0011] Accordingly, in order to increase the effective chip acquisition rate from a single wafer, the wafer size (diameter) is also increased, and the mainstream is currently shifting from 6 inches to 8 inches. .

Under such circumstances, processes such as a resist film coating process and a developing process are performed as one of the photolithography processes that are indispensable for forming a pattern for forming an element. These processing methods are performed by holding a wafer substrate by vacuum suction on a wafer chuck connected to a spin motor, and discharging a resist or developing solution onto the wafer substrate while rotating the wafer substrate. Done.

In addition to the above processing, with respect to the cleaning of the back surface of the wafer, an organic solvent or pure water is discharged from a single or a plurality of nozzles provided in a coater device or a developer device. By cleaning the back surface, the resist, the developing solution, or the adhered foreign substances adhered to the back surface of the wafer are cleaned.

However, in the above-mentioned conventional method, when the wafer is discharged onto the back surface of the wafer substrate rotating at a low speed, the discharged chemical solution or pure water is subjected to a cleaning treatment toward the outer periphery of the wafer by centrifugal force. Fig. 7
As shown by the dashed arrow in the middle, a phenomenon was observed in which wraparound also occurred from the nozzle discharge location toward the center of the wafer. When this wraparound occurs, the chemical solution or pure water penetrates between the wafer chuck and the wafer holding the wafer by vacuum suction, and a part of the back surface of the wafer substrate, and the wafer chuck are in a wet state, and foreign matter is present. Had the problem of inducing redeposition.

Therefore, in the conventional method, there is a need to provide a nozzle setting portion to be separated from the wafer chuck, so that there is a problem that an uncleaned portion occurs between the wafer chuck and the discharge nozzle.

The above problem becomes a serious problem in the future increase in the diameter of wafers because high-speed rotation becomes impossible as the diameter of the wafer is increased, and low-speed rotation is frequently used.

Therefore, in the present invention, a wafer back surface cleaning method is provided which suppresses the wraparound of the inside of the nozzle even during low speed rotation regardless of the size of the wafer size, thereby maximizing the wafer back surface cleaning effect. An object of the present invention is to provide a method of cleaning a wafer back surface in a photolithography process of a semiconductor device for cleaning foreign substances and suppressing reattachment.

[0018]

In the present invention, as a means for solving the above-mentioned problems, a resist coating process of applying a resist by spin coating on a substrate in a photolithography technique as a part of a method of manufacturing a semiconductor device, or The method according to claim 1, wherein the wafer back surface cleaning step performed when performing a developing process using a developer is performed.
The wafer back surface cleaning method in the photolithography process of the semiconductor device described in the above is performed by holding the wafer by vacuum suction on a wafer chuck connected to a spin motor unit, and cleaning the wafer back surface using a chemical solution or pure water. A structure in which a plurality of washing nozzles of at least four or more locations are arranged at equal intervals in a rotating mechanism that rotates the nozzles simultaneously with wafer rotation, and a chemical solution or pure water is discharged from the washing nozzles when the wafer is rotating. To perform the wafer back surface cleaning.

In the present invention, in contrast to the conventional method in which a chemical solution or pure water is discharged to the backside of a rotating wafer, a chemical solution is applied to a wafer chuck held by vacuum suction or a rotating portion that rotates simultaneously with the wafer. Alternatively, a structure is provided in which a nozzle for discharging pure water is provided.

According to such a method, stable discharge can always be performed on the rear surface of the wafer under constant conditions without being affected by fluctuations in the number of revolutions of the wafer, fluctuations in the discharge pressure of the chemical solution or pure water, and fluctuations in the discharge flow rate. Even when the fluctuation occurs, it is possible to prevent the chemical solution or pure water from penetrating into the wafer chuck and the wafer inside the discharge nozzle.
This is because the nozzles are installed in the rotation mechanism so that the discharge positions of the nozzles from the nozzles to the wafer are fixed positions, and the washable area per nozzle obtained from the experimental results is a minimum of 90 regardless of the number of rotations. This is possible by installing four or more cleaning nozzles.

According to a second aspect of the present invention, there is provided a method of cleaning a back surface of a wafer in a photolithography process of a semiconductor device, wherein the wafer is held by vacuum suction on a wafer chuck connected to a spin motor, and a chemical solution or pure water is used. A plurality of cleaning nozzles comprising at least four or more cleaning nozzles are arranged at regular intervals in a rotating mechanism that rotates a cleaning nozzle that performs wafer back surface cleaning simultaneously with the rotation of the wafer, and provided in the rotating mechanism. A single cleaning nozzle is provided in the outer peripheral direction of the wafer from the cleaning nozzle, or has a structure provided with a fixed cleaning nozzle composed of two or more, after discharging a chemical solution, or pure water from the cleaning nozzle provided in the rotation mechanism at the time of wafer rotation, Subsequently, the cleaning agent is discharged from the fixed cleaning nozzle, or by simultaneously discharging the cleaning agent, thereby cleaning the back surface of the wafer. And cormorants way.

With such a method, when the diameter of the wafer is increased, the outermost peripheral portion of the wafer is cleaned by providing a cleaning nozzle fixed to the outer peripheral side of the wafer remote from the wafer chuck. The above problem can be solved by supplementing the ability.

The present invention provides a cleaning method for solving the above-mentioned problem by using any of the above-mentioned methods.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional structural view of a mechanism according to a first embodiment of the present invention, and FIG. 2 is a structural view when viewed from above, which will be described below.

In FIG. 1, a wafer 1 is held on a wafer chuck 2 by vacuum suction, and a wafer back surface cleaning nozzle 4 includes a rotating mechanism, in this embodiment, a plurality of cleaning nozzles 4 from the wafer chuck 2. The structure is arranged.

The back surface cleaning nozzle 4 has a structure as close as possible to the wafer chuck 2 and adopts a structure in which an uncleaned area is reduced.

The back surface cleaning nozzle 4 provided in the rotating mechanism
Has a structure in which a plurality of cleaning nozzles including at least four or more cleaning nozzles are arranged at regular intervals from the rotation mechanism.

In the above structure, a resist coating process,
Alternatively, after the development process is completed, the back surface cleaning process is performed by discharging an organic solvent or pure water from the back surface cleaning nozzle 4.

FIGS. 3 and 4 show a cross-sectional structure and a planar structure from the top surface in the second embodiment.

In the present embodiment, the back surface cleaning nozzle 4 provided in the rotating mechanism section has a structure as close to the wafer chuck 2 as possible, as in the first embodiment. At least 4 at equal intervals
The structure is such that a plurality of cleaning nozzles 4 composed of a plurality of locations or more are arranged.

In the second embodiment, in addition to the back surface cleaning nozzle 4 of the rotation mechanism, a back surface cleaning nozzle 4B fixed to a base 5 having no rotation mechanism is provided. The back surface cleaning nozzle 4B is provided with a discharge pressure of a chemical solution or pure water,
The arrangement is set as far away from the wafer chuck 2 as possible so that it does not reach the wafer chuck 2 even when the discharge location caused by the change in the discharge flow rate causes the wafer 1 to wrap around to the center of the wafer 1.

The back surface cleaning nozzle 4 may be constituted by a single nozzle or a plurality of nozzles composed of two or more nozzles.

According to the above-described method of the present embodiment, in cleaning the back surface of the wafer after the completion of the resist coating process or the developing process, an organic solvent or pure water is discharged from the back surface cleaning nozzle 4 provided in the rotating mechanism. , And then the cleaning nozzle 4B fixed to the base 5
In the same manner, a stable back surface cleaning process can be performed by performing the cleaning using any method of performing the cleaning by discharging the cleaning agent, or performing the cleaning by discharging at the same time.

[0034]

According to the first and second methods of cleaning a semiconductor device in the photolithography process of the semiconductor device according to the present invention, the wafer back surface cleaning nozzle is installed as close to the wafer chuck side as possible. Alternatively, it is possible to avoid the permeation of pure water, and it is possible to reduce the uncleaned area and at the same time avoid the wet state, which has been caused by the conventional method, to obtain the effect of preventing the reattachment of foreign matter.

Accordingly, it is possible to avoid defocus due to the foreign matter during the exposure processing by the exposure device,
The effect of reducing the occurrence of defects can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-sectional structure of a wafer chuck according to a first embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a sectional view showing a wafer chuck according to a second embodiment of the present invention;

FIG. 4 is a plan view of FIG. 3;

FIG. 5 is a cross-sectional structural view illustrating a wafer chuck according to a conventional method.

FIG. 6 is a plan view of FIG. 6;

FIG. 7 is a sectional structural view for explaining a problem by a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Wafer (silicon substrate), 2 ... Wafer chuck, 3 ... Spin motor, 4 ... Back surface cleaning nozzle provided in rotation mechanism part, 4B ... Back surface cleaning nozzle fixed to base, 5 ... Base, 101 ... Wafer (silicon substrate), 102: wafer chuck, 103: spin motor, 104: back surface cleaning nozzle fixed to the base, 105: base.

Claims (2)

[Claims] 1. As a part of a method of manufacturing a semiconductor device, a wafer back surface cleaning performed after performing a resist coating process of applying a resist on a substrate by a photolithography technique by a spin coating method or a developing process using a developing solution. In the process, the wafer is held by vacuum suction on the wafer chuck connected to the spin motor unit, and the cleaning nozzle that cleans the back surface of the wafer using a chemical solution or pure water is rotated simultaneously with the wafer chuck or wafer. A structure in which a plurality of cleaning nozzles composed of at least four or more locations are arranged at equal intervals in any of the rotating mechanism sections to be performed, and a chemical solution or pure water is discharged from the cleaning nozzles when the wafer is rotating, so that the back surface of the wafer is rotated. Cleaning in a semiconductor device photolithography process. Doha back surface cleaning method. 2. As a part of a semiconductor device manufacturing method, a wafer back surface cleaning performed after performing a resist coating process of applying a resist on a substrate by a photolithography technique by a spin coating method or a developing process using a developing solution. In the process, the wafer is held by vacuum suction on the wafer chuck connected to the spin motor unit, and the cleaning nozzle that cleans the back surface of the wafer using a chemical solution or pure water is rotated simultaneously with the wafer chuck or wafer. In any of the rotating mechanism parts to be performed, a plurality of washing nozzles composed of at least four or more locations are arranged at equal intervals, and a single washing nozzle is provided in the outer peripheral direction of the wafer from the washing nozzle provided in the rotating mechanism part.
Alternatively, a structure is provided in which two or more fixed cleaning nozzles are provided, and when a wafer is rotated, a chemical solution or pure water is discharged from the cleaning nozzle provided in the rotation mechanism, and then the cleaning is performed from the fixed cleaning nozzle. A method of cleaning a back surface of a wafer in a photolithography process of a semiconductor device, wherein the back surface of the wafer is cleaned by discharging or simultaneously discharging the agent.