FR2662518A1 - METHOD FOR MANUFACTURING A MASK - Google Patents

Abstract

A method of manufacturing a mask having a phase shift region (19) comprising the steps of: applying an opaque mask plate (13) and a photosensitive film (15) to a surface of a transparent substrate (11); exposing a predetermined portion of the mask plate; exposing a predetermined portion of the substrate by etching an exposed portion of the mask plate; forming a pattern region (17) by etching the substrate to a predetermined thickness; forming a phase shift region (19) by horizontally etching the side of the mask plate; and removing the photosensitive film. Application to the production of semiconductor devices with a high degree of integration.

Description

Method of manufacturing a mask

  The present invention relates to a method of manufacturing a mask, and in particular to a method of manufacturing a mask having a phase shift region that can improve the resolution of the pattern.

  Generally speaking, in a manufacturing process

  cation of a semiconductor device, a circuit pattern

  integrated cooking is formed on the surface of a slice by

  The photolithographic process comprises an exposure step that selectively reproduces a desired pattern on the photosensitive varnish applied to the wafer, projecting ultraviolet light (hereinafter referred to as UV), etc. As exposure methods, a distinction is made between

  a contact method, a proximity method and a

  However, according to the trend towards obtaining a semiconductor device with a very high degree of integration, a line width of a circuit becomes thinner, so that the use of the aforementioned methods has limitations. On the other hand, there is another method of exposure called a step-by-step process. The step-by-step method can provide a finer line width such that a mask that is five to ten times as large as a pattern of chip is used and the exposure is performed by a method of advancing a step and

repetition.

  However, in the step-by-step process, when the projected UV radiation passes through the mask pattern,

  is diffracted and, as a result, the resolution of the

  produced on the photosensitive film is impaired Thus, it is impossible to apply the process to manufacturing

  of a semiconductor device having a degree of

  high integration such as a 16M DRAM or higher.

  Thus, another method is suggested in which, when the light is projected onto the mask and passes through the predetermined pattern, the phase of the light passing through the

  neighboring pattern is out of phase by 1800 to prevent the diffraction

  By means of an improvement in the resolution of the pattern, that is to say that in the mask having a layer or region of phase shift, the phase of

  light projected on a part other than the pre-

  predetermined is out of phase by 1800, so that we can ob-

  hold a point where the intensity of the light is zero.

  Figures 1A-1D show a conventional method of manufacturing a mask having a phase shift layer. Referring to Figure 1A, a mask plate

  3 and a light-sensitive film 5 are successively

  placed on the glass substrate 1 The mask plate 3

  consists of Cr, an emulsion, or ferric oxide.

  Referring to Figure 1 B, the grating pattern is exposed to light on the light-sensitive film 5

  using ultraviolet radiation Then the film

  The photosensitive film 5 is developed to remove the exposed portion of the photosensitive film. Next, the exposed portion of the mask plate 3 is etched using the resulting photosensitive film as

  engraving mask, and the pattern is formed.

  With reference to Figure 1C, after the plate

  mask 3 was exposed by eliminating the

  5, the mask plate 3 formed on the glass substrate is inspected and the defects are repaired. Next, a photosensitive film 7 is applied to the exposed portion of the glass substrate 1 and the surface of the plate.

mask 3.

  Referring to Fig. 1D, UV radiation is projected through the lower surface of the glass substrate 1 without using a grating at this time, since the mask plate 3 is opaque, the light-sensitive film 7 formed only on the surface of the glass substrate 1 glass substrate 1

  The photosensitive film 7 is then exposed.

  veloppée and then the exposed part is eliminated Then

  the mask plate 3 is horizontally supergraded using

  reading the photosensitive film 7 as an etching mask Said light-sensitive film 7 is not removed,

  but is used as the phase shift layer of the mask.

  In the mask manufactured by the aforementioned method, the thickness of the photosensitive film used as

  phase shift layer is very important, and this thick

  of the photosensitive film is controlled by the screw

  costivity of the photosensitive solution and the rotational speed

  spray device when the solution

  photosensitive is applied by spraying in the

  photomasks of a semiconductor element, the thickness of

  of the photosensitive film to phase out the projected light of 1800 is given by dl 2 (n 1 1) where d is the thickness of the light-sensitive film, X is

  the wavelength of the projected light, and N 1 is the

  refractive index of the light-sensitive film

  if the thickness of the light-sensitive film used

  As a phase shift layer satisfies the above equation, the phase of the light projected onto the surface of the light-sensitive film is shifted to the

  zero point of light intensity, so that the resolu-

pattern is improved.

  However, in the conventional process of

  after inspection and repair, the mask

  tomasking and overgrading of the mask plate are

  again, so the process is very complicated.

  In addition, the thickness of the phase shift layer varies according to the viscosity of the photosensitive solution.

  and the speed of rotation during the application of the

  photosensitive release, can not be controlled easily, and a rung exists between the glass substrate and the plate

  of the mask, so that the topography of the photographic film

  tosensitive degrades and the thickness of the dewatering layer

  Also, since the phase shift layer is formed by the photosensitive film, the mask is easily damaged, and when the mask is damaged, the phase shift layer can not be formed.

and used again.

  Therefore, one of the purposes of this invention is

  It is to provide a method of manufacturing a mask having a phase shift region by a simple process.

  Another object of the present invention is to

  a method of manufacturing a mask having a

  semipermanent phase shift region.

  In order to achieve the above objects, the method of manufacturing a mask having a phase shift region according to the present invention comprises the steps of

  apply an opaque mask plate and pel-

  light-sensitive acid on a surface of a trans-

  parent expose a predetermined part of the plate of

  mask by exposing and developing a predefined part

  born of photosensitive film; exposing a predetermined portion of the substrate by etching an exposed portion of the mask plate forming a pattern region by etching the substrate to a predetermined thickness;

  to form a region of phase shift by engraving horizon-

  the side of the mask plate; and

  remove the photosensitive film.

  The above goals and other benefits

  of the present invention will become more apparent from the description

  In the preferred embodiment of the present invention, reference is made to the accompanying drawings, in which FIGS. 1A to 1D show a conventional method of manufacturing a mask; Figures 2A to 2D show a method of manufacturing a mask according to the present invention; Figure 3 and Figure 4 show the states of light after passing through the mask when the light is projected; and Figure 5 shows an example of application of the mask made according to the present invention, in which

  it is used in the process of making a device

semiconductor system.

  Figures 2A to 2D represent a mode of realization.

  preferred method of manufacturing a mask according to

the present invention.

  Referring to Figure 2A, a mask plate 13 and a light-sensitive film 15 are successively formed on the surface of a conventional glass substrate. The mask plate 13 is made of Cr, ferric oxide, or an emulsion with a thickness of approximately 1000 A.

  Referring to FIG. 2B, the photo film

  sensitive 15 is irradiated by UV rays, etc. to form

  a network pattern Next, the exposed part of the film

  The photosensitive particle 15 is developed and then the predetermined portion of the mask plate 13 is exposed.

  using the non-eliminated part of the photo-film

  sensitive as a masking mask, the expo-

  Mask plate 13 is etched when the mask plate is made of Cr, hydrochloric acid or

  acetic acid is used as an etching solution

  because the thickness of the mask plate 13 is as thin as 1000 A, horizontal etching can be

to be neglected.

  With reference to Figure 2C, using the pel-

  as the etching mask, the exposed portion of the substrate 11 is etched to a predetermined depth by a glass etching agent, etc. The difference in thickness d between the engraved portion and the portion

  non-etched substrate It must satisfy the following equation:

  vante: d 2 (n 1) (n: refractive index)

  Referring to Figure 2 D, using the pel-

  as the etching mask, the side of the mask plate 13 is etched horizontally with hydrochloric or acetic acid. The exposed portion of the substrate 11 becomes a phase shift region 19, and at this time the width W of the phase shift region 19 is correct and between 0.2 and 0.3 μm. Also, the etched portion of the substrate 11 becomes a pattern region 17. The photosensitive film 15 is then removed and

the mask is then completed.

  Figure 3 and Figure 4 represent respectively

  a phase state and the light intensity passing through the pattern region 17 and the phase shift region 19 when a

  light such as UV is projected onto the mask On the

  gure 3, parabola (a) represents the phase of light

  crossing a pattern region 17 and the parabola (b) representing

  the phase of light passing through a region of

  The phase of the light passing through the phase shift region 19 is out of phase by 1800 with respect to the light passing through the pattern region 17. Also, in FIG. 4, the parabola (a ') represents the light intensities.

  crossing a pattern region 17, and the parabola (b ')

  presents the luminous intensities passing through a region of phase shift 19 In the Figure, the parabolas (a ') and (b') are

  meet at the zero point of the light intensity That is to say

  say that there is a zero point of light intensity between

  the pattern region 17 and the phase shift region 19.

  Figure 5 shows an example of the application of the mask manufactured by the method of the present invention.

  to a process for manufacturing a semiconductor device

  on which reference numeral 21 designates a

  semiconductor substrate and the reference numeral 23

  a photosensitive film Reference number 25

  designates a part that is exposed and developed by the

  In addition, the reference numeral 27 indicates a point corresponding to the zero point of the light intensity between the pattern region.

  17 and the phase shift region 19 during an exposure step

  and its fineness indicates that the motive resolution of

  the photosensitive film 23 is excellent.

  As described above, since the pattern region and the phase shift region are formed using the same photosensitive film as the etch mask, the thickness difference between the pattern region and the region

  phase shift can be easily controlled.

  Thus, in the present invention, the difference in thickness between the phase shift region and the pattern region can be exactly controlled by etching, and the

  phase shift region is formed as part of the sub-

  strat, so that a mask with increased longevity can be

easily made.

9 2662518

Claims (3)

R E V E N D I C A T IO N S   A method of manufacturing a mask having a phase shift region, characterized in that it comprises the steps of: applying an opaque mask plate (13) and   a light-sensitive film (15) on a surface of a substrate   transparent stratum (11), exposing a predetermined portion of said plate   mask by expounding and developing a predefined part   from the photosensitive film, exposing a predetermined portion of the substrate by etching an exposed portion of the mask plate, forming a pattern region (17) by etching said substrate to a predetermined thickness, forming a phase shift region (19) by etching horizontally the side of said mask plate, and   removing said light-sensitive film.   2 A method of manufacturing a mask according to the   1, characterized in that during said step of forming a pattern region, the etching is performed so as to phase out the respective lights passing through the pattern region (17) and the phase shift region (19).   3 A method of manufacturing a mask according to the   2, characterized in that said region of   phase shift (19) is performed with a width of 0.2 to 0.3 μm.