KR20100111131A - Method for manufacturing phase shift mask - Google Patents

Abstract

PURPOSE: A manufacturing method of a phase shift mask is provided to compensate the changed phase shift value generated by over-etching a substrate. CONSTITUTION: A manufacturing method of a phase shift mask comprises the following; forming a light shielding pattern and a phase shift layer pattern(130) on a light penetrating substrate(100); partially exposing the surface of the light penetrating substrate and the phase shift layer pattern by removing the light shielding pattern; measuring the phase value and the transmissibility at the over-etched phase shift layer pattern while removing the light shielding pattern; forming a compensation film(135) on the rear side of the light penetrating substrate; and recessing the compensation layer.

Description

Method for manufacturing phase shift mask

The present invention relates to a photomask, and more particularly to a method of manufacturing a phase inversion mask.

The photomask serves to form a desired pattern on the wafer while irradiating light on the mask pattern formed on the substrate to selectively transmit the light to the wafer. Such photomasks have generally used a binary mask including a light-transmitting region through which light is transmitted and a light-blocking region through which light is blocked by forming a light blocking layer pattern including chromium (Cr) on a substrate. However, as the degree of integration of semiconductor devices increases, the size of the pattern becomes finer, making it difficult to accurately implement a desired pattern due to diffraction or interference of light passing through the binary mask. Accordingly, in order to overcome difficulties in implementing accurate patterns, a phase shift mask using a phase shift material having a transmittance of several percent has been proposed and applied.

The phase shift mask forms a phase shift film and a light blocking film on a substrate, and performs a patterning process including writing and pattern transfer steps to form a mask pattern to be transferred to a wafer. In order to form a mask pattern, first, a mask pattern to be transferred onto a wafer is primarily implemented as a light blocking film pattern. Next, the exposed portion of the phase shift film is etched using the light blocking film pattern implemented as an etch mask to form a phase shift film pattern. When the light blocking layer pattern of the special region is removed from the circuit pattern portion, the phase inversion layer pattern suitable for the purpose is exposed and the fabrication of the mask pattern is completed.

Meanwhile, in the process of forming the phase shift layer pattern by etching the phase shift layer using the light blocking layer pattern as an etch mask, the exposed phase shift layer is over etched over the target thickness or is less than the target thickness to be etched (under). may be etched). When the etching is excessively etched or smaller than the target thickness of the phase shift film to be etched, the phase shift value of the light source passing through the phase shift film pattern is 180 degrees higher or lower than the target phase difference, and as a result, the desired pattern is transferred to the wafer. There is a problem that is difficult to do. In particular, when the phase inversion film is etched excessively than the target thickness, it is difficult to compensate for the excessively etched portion, which causes a defect in the minimum critical dimension of the pattern implemented in the wafer. Accordingly, there is a need for a method of correcting a value in which a phase difference caused in the process of etching the phase inversion film is higher than a target phase difference.

The technical problem to be achieved by the present invention is to provide a method of manufacturing a phase inversion mask that can compensate for the phase difference value is excessively etched by the method of compensating the thickness of the phase inversion film is excessively etched in the process of manufacturing the phase inversion mask. have.

A method of manufacturing a phase shift mask according to the present invention may include forming a phase shift pattern and a light blocking layer pattern exposing a part of a surface of the transparent substrate on a transparent substrate; Removing the light blocking film pattern to expose a portion of the surface of the phase shift film pattern and the light transmitting substrate; Measuring the phase value and transmittance of the phase inversion film pattern etched excessively than a target thickness while removing the light blocking film pattern; Forming a compensation film on a rear surface of the translucent substrate corresponding to the surface on which the phase shift film pattern is formed; And recessing the compensation layer by a predetermined thickness such that the phase value of the overly etched phase inversion layer pattern is located at 180 degrees.

In the present invention, the compensation film is preferably formed of the same material as the phase inversion film pattern.

The compensation film is formed to a thickness of 600 kW to 760 kW based on a mask using ArF wavelength, and is 900 kW to 960 kW based on a mask using KrF wavelength.

The compensation film has a thickness of 53.87% for a mask using ArF wavelength, 20.36% for a mask using KrF wavelength, and an I-LINE mask is recessed to a thickness of 15.14%.

The compensation film is recessed by performing a cleaning process or an etching process, and the cleaning time for performing the cleaning process or the etching time for performing the etching process is set by dividing by the amount of etching that the compensation film is etched per hour.

The cleaning time or the etching time may be set based on the transmittance (%) and the light compensation value (LC) based on the measurement data extracted from the phase value and the transmittance meter, or the thickness change of the compensation film may be measured in the cleaning process or the etching process. The correlation between the transmittance (%) and the light compensation value (LC) in the measuring device for the numerical value is compared and set.

According to the present invention, a phase inversion film may be formed on the rear surface of the substrate by an excessively etched thickness, and the cleaning process or the etching process may be performed to compensate for the lost phase difference value.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

1 to 9 are diagrams for explaining the method of manufacturing a phase shift mask according to an embodiment of the present invention.

Referring to FIG. 1, a blank mask having a structure in which a phase inversion film 105, a light blocking film 110, and a resist film 115 is deposited on a light transmissive substrate 100 is prepared. The transparent substrate 100 is made of a transparent material that can transmit light, and includes quartz. The phase inversion film 105 formed on the light transmissive substrate 100 is made of a material having a transmittance of several percent and includes a compound containing molybdenum (Mo). The compound containing molybdenum (Mo) may be formed including molybdenum silicon oxynitride (MoSiON). Next, the light blocking film 110 deposited on the phase inversion film 105 is a light blocking film for selectively blocking the light transmitted to the light transmitting substrate 100 in a subsequent exposure process. The light blocking film 110 may include a chromium film Cr. The resist film 115 includes a positive type resist material from which an energy-injected portion of the exposure process is removed during the development process.

Referring to FIG. 2, a resist film pattern partially exposing the surface of the light blocking film 110 (see FIG. 1) by performing a lithography process including an exposure process and a developing process on the resist film 115 (see FIG. 1). Form 120. Specifically, an exposure process using an electron beam (E-beam) device is performed on the resist film 115. Then, a difference in solubility due to a photochemical reaction occurs between a portion irradiated with light and a portion not irradiated with light on the resist film 115. Next, when the development process is performed, a portion of the resist film 115 is removed by the developer, thereby forming a resist film pattern 120 exposing a part of the surface of the light blocking film 110. Subsequently, the exposed portion of the light blocking film 110 is etched using the resist film pattern 120 as an etch mask to form a light blocking film pattern 125 that selectively exposes the phase inversion film 105.

Referring to FIG. 3, the exposed portion of the phase shift film 105 (see FIG. 2) is etched using the light blocking film pattern 125 as an etch mask to form the phase shift film pattern 130.

Referring to FIG. 4, the light blocking layer pattern 125 on the phase inversion layer pattern 130 is removed to expose the phase inversion layer pattern 130. The light blocking film pattern 125 to be removed is a light blocking film pattern formed in the main cell area to be transferred to the wafer. Although not shown, the light blocking film pattern of the frame area is not removed. The light blocking layer pattern 125 removes a point where the surface of the phase shifting pattern 130 is exposed as a target. Next, the phase value and transmittance of the phase inversion film pattern 130 formed on the substrate 100 are measured. The phase value and transmittance are measured by a phase difference meter or a transmittance meter.

In this case, in the process of removing the light blocking layer pattern 125, the phase inversion layer pattern 130 is overetched more than the target thickness T1 and is formed to have a thickness T2 lost by a predetermined thickness from the surface. have. Alternatively, although not shown in the drawings, the etching may be etched smaller than the target thickness to be etched. When the phase shift layer pattern 130 is excessively etched or etched with a loss thickness T2 lower than the target thickness T1, the phase shift layer pattern 130 passes through the phase shift layer pattern 130 in an exposure process for transferring the mask pattern onto the wafer. The phase shift value of the light source is higher or lower than 180 degrees, which is the target phase shift value. As such, when the phase value is different from the target phase shift value, there is a problem that it is difficult to accurately transfer the pattern to the wafer. In particular, when the phase shift pattern 130 is excessively etched than the target thickness T1, it is difficult to compensate for the excessively etched portion d1, so that a defect in the minimum critical dimension of the pattern implemented in the wafer is difficult. May occur. Accordingly, there is a need for a method of compensating for the changed phase shift value when the etching is excessively etched and the phase shift value becomes higher than 180 degrees, which is the target phase shift value.

Referring to FIG. 5, a compensation film 135 is coated on the rear surface of the light transmissive substrate 100. The compensation layer 135 may be formed of the same material as the phase inversion layer pattern 130, for example, molybdenum silicon oxynitride (MoSiON). The compensation layer 135 is formed to a thickness of 600 kHz to 760 Å based on the mask using the ArF wavelength, preferably 680 Å thick. In addition, the compensation layer 135 is formed to a thickness of 900 Å to 960 으로 는 based on the mask using the KrF wavelength, preferably 933 Å.

Referring to FIG. 6, a cleaning process or an etching process is performed on the rear surface of the transmissive substrate 100 coated with the compensation film 135 (see FIG. 5) to convert the initial thickness d2 of the compensation film 135 into a phase shift compensation thickness ( d3). In some cases, both the washing step and the etching step may be performed. Here, in the cleaning process or the etching process, in the phase value and transmittance measurement performed after removing the light blocking film pattern 125, the thickness of the compensation layer 135 is compensated for the variation of the phase value and transmittance measurement value according to the mask type. The thickness d3 is adjusted to implement a phase value suitable for each mask. Specifically, the transmittance according to the mask type has a transmittance of 53.87% for a mask using ArF wavelength at 365 nm wavelength, a transmittance of 20.36% for a mask using KrF wavelength, and a transmittance of 15.14% for I-LINE mask. Accordingly, the compensation layer 135 is adjusted to have a thickness satisfying each transmittance. For this purpose, as shown in FIGS. 8 and 9, the transparent substrate 100 coated with the compensation layer 135 is disposed in the etching apparatus 200 (see FIG. 8) or the cleaning apparatus 215 (see FIG. 9). The cleaning process and the etching process are performed. Here, the cleaning device 215 is a spin method for cleaning while rotating in one direction, and may proceed even after the pellicle 210 is attached. The etching process is performed by using an etching source for etching the compensation layer 135, and when the compensation layer 135 is made of the same material as the phase shift pattern 130, the etching process for etching the phase shift pattern 130 is performed. You can proceed using the source. In this case, the portion not described in the drawing is the light blocking film frame pattern 200. The cleaning time and the etching time may be performed by designating a cleaning time or an etching time for splitting according to the amount of etching of the compensation film per hour to reach the phase shift compensation thickness d3. The cleaning time and the etching time may be applied as a recipe for an etching process based on transmittance (%) and light calibration (LC) based on measurement data extracted from a phase value and a transmittance meter. . In addition, the correlation between the transmittance (%) and the light compensation value (LC) of the measuring device for the thickness value of the compensation film 135 that is changed during the cleaning process or the etching process may be applied to the etching process. .

 Next, referring to FIG. 7, phase values and transmittances of the light-transmitting substrate 100 on which the compensation film 135 and the phase inversion film pattern 130 having the phase values compensated are measured. The phase value and the transmittance are measured by the phase difference meter or the transmittance meter 140. In addition, the compensation value 135 may be further cleaned or etched with respect to the fluctuation range of the measured values of the phase value and the transmittance to adjust the phase value and the transmittance.

On the other hand, it may be etched smaller than the target thickness (under etch) may cause the phase shift value of the light source to be lower than 180 degrees which is the target phase shift value. In the case of having a phase value lower than the target phase shift value, a process of additionally etching the pattern surface of the phase shift film pattern is performed, and then the phase value and transmittance of the additional etched phase shift film pattern are measured to determine the range of the target phase shift value. If it is inside, the subsequent process is performed, and if it is out of range, the etching process is performed again to adjust the phase value and transmittance.

In the method of manufacturing a phase shift mask according to the present invention, when a phenomenon in which the phase shift value is higher than 180, which is a target phase shift value, is formed, a compensation film is formed on the rear surface of the substrate, and the compensation film is subjected to a cleaning process or an etching process to perform a phase value. And by compensating for the transmittance, an accurate pattern to be transferred to the wafer can be realized.

1 to 9 are diagrams for explaining the method of manufacturing a phase shift mask according to an embodiment of the present invention.

Claims (8)

Forming a phase inversion film pattern and a light blocking film pattern exposing a portion of the surface of the light transmissive substrate on the light transmissive substrate; Removing the light blocking film pattern to expose a portion of the surface of the phase shift film pattern and the light transmitting substrate; Measuring the phase value and transmittance of the phase inversion film pattern etched excessively than a target thickness while removing the light blocking film pattern; Forming a compensation film on a rear surface of the translucent substrate corresponding to the surface on which the phase shift film pattern is formed; And And recessing the compensation layer by a predetermined thickness such that the phase value of the overly etched phase shift pattern is located at 180 degrees. The method of claim 1, The method of claim 1, wherein the compensation layer is formed of the same material as the phase shift pattern. The method of claim 1, The compensation film is formed with a thickness of 600 kHz to 760 kHz based on a mask using an ArF wavelength, and a 900 to 960 kHz thickness based on a mask using a KrF wavelength. The method of claim 1, The compensation film is a phase inversion mask manufacturing method that the mask using the ArF wavelength has a transmittance of 53.87%, the mask using the KrF wavelength has a transmittance of 20.36%, the I-LINE mask is recessed to a thickness having a transmittance of 15.14%. . The method of claim 1, The compensation film is a phase inversion mask manufacturing method to be recessed by performing a cleaning process or an etching process. The method of claim 5, The cleaning method for the cleaning process or the etching time for performing the etching process is a phase inversion mask manufacturing method that is set by splitting (set) by the amount of etching that the compensation film is etched per hour. The method of claim 6, The cleaning time or the etching time is a phase inversion mask manufacturing method that is set based on the transmittance (%) and the light compensation value (LC) based on the measurement data extracted from the phase value and the transmittance meter. The method of claim 6, The cleaning time or the etching time is a phase inversion set by comparing the correlation between the transmittance (%) and the light compensation value (LC) in the measuring device with respect to the numerical value of the thickness change of the compensation film in the cleaning process or etching process. Mask manufacturing method.

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