Mask plate for laser processing

Abstract

The utility model relates to a mask plate for laser processing, which comprises a substrate, a reflecting film is arranged on one surface, deviating from a laser light source, of the substrate, and the reflecting film comprises a plurality of film layers which are sequentially arranged along the direction perpendicular to the surface of the substrate; the plurality of film layers comprise a plurality of silicon oxide layers and a plurality of tantalum oxide layers which are alternately arranged. The mask plate provided by the utility model can be relatively long in service life on the premise of ensuring relatively high reflectivity and processing efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to a semiconductor device manufacturing process, in particular to a mask plate used when a laser is used as a light source to process a semiconductor device. BACKGROUND

[0002] In the field of traditional mask plate (also known as mask) processing, an ultraviolet light source or a visible light source is usually used to irradiate the mask plate. The energy of the light source penetrates the mask plate and forms a pattern on the photoresist to achieve the purpose of processing a pattern on the semiconductor device. Generally speaking, if the above light source is used, the mask plate can be made of chromium-plated glass, and the thickness of the chromium layer is about 0.1-0.2 μm, which can achieve the effect of light shielding. This process is relatively mature, but the processing precision is limited.

[0003] In order to improve the processing precision, a laser can be used as a light source. Because the laser has very high energy and excellent collimation, it can achieve nanometer-level precision processing. However, the problem that arises is that if the traditional mask plate is still used at this time, due to the low reflectivity of the chromium layer to light, the chromium layer is prone to fall off or have a gap after absorbing a large amount of high-energy laser, which ultimately affects the service life of the mask plate.

[0004] Therefore, there is an urgent need in the industry to provide a mask plate that can effectively reflect laser light but has high light transmittance, while not affecting normal laser processing. CONTENT OF THE INVENTION

[0005] In view of this, the present application provides a mask plate for laser processing, comprising a substrate, one side of the substrate away from the laser light source has a reflective film, the reflective film comprises a plurality of film layers arranged in turn along the direction perpendicular to the surface of the substrate; the plurality of film layers comprise a plurality of silicon oxide layers and a plurality of tantalum oxide layers arranged alternately.

[0006] Further, the film layer farthest from the laser light source is a bottom film layer, and the bottom film layer is a silicon oxide layer.

[0007] Further, the film layer closest to the laser light source is a top film layer, and the top film layer is a tantalum oxide layer.

[0008] Further, the thickness of each silicon oxide layer is a, and the thickness of each tantalum oxide layer is b, b < a < 3.5b.

[0009] Further, 40 nm < b < 80 nm.

[0010] Further, the thickness of the bottom film layer is between 160 nm and 200 nm.

[0011] Further, the total number of the film layers is n, 15≤n≤30.

[0012] Further, the thickness of the substrate is between 0.1mm and 20mm.

[0013] Further, the side of the substrate facing the laser light source is provided with an antireflection film.

[0014] Further, the antireflection film is one or more of magnesium fluoride antireflection film, titanium oxide antireflection film, lead sulfide antireflection film, lead selenide antireflection film, ceramic infrared light antireflection film, and vinyl silsesquioxane hybrid antireflection film.

[0015] Further, the number of layers of the antireflection film is at least 2, and different layers of the antireflection film have different light transmission wave bands.

[0016] Further, the reflective film is located on the substrate including an opaque area and a light-transmitting area, the reflective film is arranged in the opaque area, and the antireflection film is arranged in the light-transmitting area.

[0017] The technical solution of the present application has at least the following technical effects:

[0018] 1. The mask provided by the present application is particularly suitable for use on a laser processing machine with a laser wavelength of 532nm and a laser incidence angle of about 15°. The reflective film is formed by alternately stacking a certain number of silicon oxide layers and tantalum oxide layers in a reasonable thickness ratio. In a preferred embodiment, the thickness of the tantalum oxide layer (i.e. the reflective layer, the tension layer) in the reflective film is 60nm, the thickness of the silicon oxide layer (i.e. the refractive layer, the pressure layer) in the reflective film is 90nm, and the number of layers alternately stacked is between 15 and 30. At this time, when the reflective film is irradiated by laser light, a high reflectivity can be achieved under the premise of ensuring normal processing, so that the mask is not easily accelerated to failure due to the absorption of high-energy laser light; at the same time, the difficulty and cost of producing the mask are also controlled within an acceptable range.

[0019] 2. In the mask provided by the present application, the substrate is made of quartz glass material, the side facing the light source is attached with a reflective film, and the side away from the light source is attached with an antireflection film, which can further improve the light transmission rate, and one or more antireflection films can be selected to cover as many laser wave bands as possible according to special wave band laser. According to experiments, if the preferred scheme is implemented, the light transmission rate of the entire mask can reach 99.5%, and the service life and laser processing effect will not be affected. BRIEF DESCRIPTION OF DRAWINGS

[0020] FIG. 1 is a structural schematic diagram of the mask of the first embodiment of the present application; Figure 1

[0021] FIG. 2 is a structural schematic diagram of the mask of the second embodiment of the present application; Figure 2 ​Structure diagram of a reflective film according to the first embodiment of the present application;

[0022] Figure 1 Figure 3 Structure diagram of a reflective film according to the second embodiment of the present application;

[0023] Figure 2 Figure 4 Structure diagram of a mask according to the third embodiment of the present application.

[0024] Wherein:

[0025] 100 - mask

[0026] 10 - substrate; 11 - reflective film; 12 - antireflection film

[0027] 111 - tantalum oxide layer; 112 - silicon oxide layer

[0028] F - direction perpendicular to the surface of the substrate 10. DETAILED DESCRIPTION

[0029] It should be noted that the components in the various figures can be shown exaggerated in size for illustration purposes and are not necessarily to scale. In the various figures, identical or similar components are provided with the same reference numerals.

[0030] In the present application, unless otherwise specified, "arranged on", "arranged above" and "arranged over" do not exclude the presence of an intermediate object between them.

[0031] In the present application, the various embodiments are merely intended to illustrate the scheme of the present application and should not be understood as limiting.

[0032] In the present application, unless otherwise specified, the quantifier "one", "a" does not exclude the scenario of multiple elements.

[0033] It should also be noted here that, in the embodiments of the present application, for the sake of clarity and simplicity, only a part of the components or assemblies can be shown, but those skilled in the art can understand that, under the guidance of the present application, the required components or assemblies can be added according to the specific scene needs.

[0034] It should also be noted here that, within the scope of the present application, the words "same", "equal", "equal" do not mean that the two values are absolutely equal, but allow a certain reasonable error, that is, the words also cover "basically the same", "basically equal", "basically equal".

[0035] The present application will be further described below according to specific embodiments.

[0036] First embodiment:

[0037] like Figure 1 As shown, this application includes a photomask 100, which comprises a substrate 10. The substrate 10 can be made of soda ash or quartz glass, preferably quartz glass. The thickness of the substrate 10 is between 0.1 mm and 20 mm. A laser processing machine with a laser wavelength of 532 nm and a laser incident angle of approximately 15° is used to perform photolithography on the semiconductor workpiece. A reflective film 11 is provided on the side of the substrate 10 facing away from the light source. The reflective film 11 is a mask layer, which is set on the side of the substrate 10 facing away from the light source according to the pattern. The reflective film 11 is used to reflect and block light. The area where it is set is the light-shielding area of ​​the substrate 10. The area on the substrate 10 not covered by the reflective film is the light-transmitting area, through which light is projected onto the workpiece.

[0038] like Figure 2 As shown, the reflective film 11 is composed of multiple film layers, including alternating tantalum oxide layers 111 and silicon oxide layers 112, which are distributed sequentially along a direction F perpendicular to the surface of the substrate 10. In this embodiment, the film layer closest to the substrate 10 (i.e., the top film layer) is the tantalum oxide layer 111, and the film layer farthest from the substrate 10 (i.e., the bottom film layer) is the silicon oxide layer 112. All tantalum oxide layers 111 have the same thickness of 60 nm; all silicon oxide layers 112 have the same thickness of 90 nm. In fact, through experiments, if the thickness of each silicon oxide layer 112 is named 'a' and the thickness of each tantalum oxide layer 111 is named 'b', the reflective film 11 will have a better reflective effect when the values ​​of a and b satisfy b < a < 3.5b; in addition, through testing different thicknesses, the reflective film 11 will also have a better reflective effect when b satisfies 40 nm < b < 80 nm compared to values ​​outside this range. In fact, in this embodiment, a = 90nm and b = 60nm are both within the above-mentioned range. Regarding the total number of film layers, n, if the value of n is low, the reflectivity will be significantly insufficient. In this embodiment, n = 20 layers is chosen, but a range of 15-30 layers should be considered a feasible solution; if the value of n is too high, the processing difficulty will increase. The reflectivity of the reflective film to strong lasers is greater than or equal to 99.5%.

[0039] Second embodiment:

[0040] As attached Figure 3As shown, the second embodiment differs from the first embodiment in that the thickness of the bottom film layer is greater than the thickness of the other film layers, and the thickness of the other film layers remains unchanged. Here, it is considered that the bottommost film layer of the mask will inevitably be abraded during actual use, and a certain thickness should be reserved, but the thickness should not be too thick, which will affect the reflection effect of the entire mask. In this embodiment, the thickness of the bottom film layer, i.e., the bottom silicon oxide layer 112, is 180 nm, but within the range of 160 nm-200 nm, it should be understood as a feasible solution; the thickness of the remaining silicon oxide layer 112 is still 90 nm, and the thickness of the tantalum oxide layer 111 is still 60 nm, and the above preferred values are still within the range of b < a < 3.5b, 40 nm < b < 80 nm in the first embodiment.

[0041] Third embodiment:

[0042] As shown in the accompanying drawings, Figure 4 The third embodiment differs from the first embodiment in that a antireflection film 12 is further provided on the side of the substrate 10 facing the light source, which can further improve the light transmittance. In particular, since one layer of antireflection film usually only has antireflection effect on a certain waveband of light, in order to obtain better light transmittance and lithography effect, at least two layers of antireflection film 12 are preferably used, so that as many wavebands of light as possible have antireflection effect, which can meet the scene with special waveband requirements for laser.

[0043] The antireflection film 12 and the reflection film 11 are arranged on both sides of the substrate 10 according to the mask pattern, and the antireflection film 12 is arranged on the light transmission area of the substrate 10.

[0044] As for the material of the antireflection film, one (when a single layer of antireflection film is provided) or multiple (when at least two layers of antireflection film are provided) of fluorinated magnesium antireflection film, titanium oxide antireflection film, lead sulfide antireflection film, lead selenide antireflection film, ceramic infrared light infrared antireflection film, and ethylene vinyl siloxane hybrid antireflection film can be selected.

[0045] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or alternative embodiments within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A mask for laser processing comprising a substrate, characterized in that: The substrate has a reflective film on the side facing away from the laser light source, the reflective film comprising a plurality of film layers arranged in sequence in a direction perpendicular to the surface of the substrate; the plurality of film layers comprising a plurality of silicon oxide layers and a plurality of tantalum oxide layers arranged alternately.

2. The mask according to claim 1, wherein: The film layer farthest from the laser light source is a bottom film layer, and the bottom film layer is a silicon oxide layer.

3. The mask of claim 1, wherein: The film layer closest to the laser light source is a top film layer, and the top film layer is a tantalum oxide layer.

4. The mask of claim 1, wherein: The thickness of each silicon oxide layer is a, and the thickness of each tantalum oxide layer is b, b < a < 3.5b.

5. The mask of claim 4, wherein: 40nm < b < 80nm.

6. The mask of claim 2, wherein: The thickness of the bottom film layer is between 160nm and 200nm.

7. The mask according to any one of claims 1-6, wherein: The total number of film layers is n, and 15 ≤ n ≤ 30.

8. The mask of claim 1, wherein: The thickness of the substrate is between 0.1mm and 20mm.

9. The mask of claim 1, wherein: The side of the substrate facing the laser light source is provided with an anti-reflection film.

10. The mask of claim 9, wherein: The anti-reflection film is one or more of a magnesium fluoride anti-reflection film, a titanium oxide anti-reflection film, a lead sulfide anti-reflection film, a lead selenide anti-reflection film, a ceramic infrared anti-reflection film, and a vinyl silsesquioxane hybrid anti-reflection film.

11. The mask of claim 9, wherein: The anti-reflection film has at least two layers, and different layers of the anti-reflection film have different light transmission wavelength bands.

12. The mask of claim 9, wherein: The reflective film is located on the substrate, which comprises an opaque region and a transparent region, the reflective film is arranged in the opaque region, and the anti-reflection film is arranged in the transparent region.

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