Method for reducing pinholes in film layer, film layer and photomask substrate

Abstract

The invention discloses a method for reducing pinholes in a film layer, the film layer and a photomask substrate. The method for reducing the pinholes in the film layer comprises the steps of forming a bright chromium layer by adopting a magnetron sputtering process in a specific process gas distribution mode, forming an oxide layer on the bright chromium layer and the like, has strict process parameter control, and further comprises the step of pre-treating a sputtering cavity and the like, so that the performance of the film layer is improved, and the yield of the film layer is improved. Products are prevented from being broken, sunken, white defects, sawtooth edges and other defects, and the film layer forming quality is improved. And particularly, by controlling the use ratio of CO2 in the bright chromium layer, the generation of particles in the bright chromium layer is greatly reduced, and the condition that particles on the surface of the whole plate are abnormal is avoided. The film layer produced by the method has the characteristics of low reflectivity, acid and alkali resistance, corrosion resistance, uniformity and the like, the product quality and performance of the photomask substrate with the film layer are improved, the conditions of thin film light leakage, poor product exposure and development and the like caused by pinholes are avoided, and the yield and quality reliability of the photomask substrate are improved.

Description

Technical Field

[0001] The invention relates to the technical field of mask glass substrate coating, and in particular to a method for reducing pinholes in a film layer, a film layer and a photomask substrate. Background Art

[0002] The photomask substrate is mainly composed of glass + film layer + adhesive layer, and the film layer is the most important existence that affects the mask substrate. The film layer formation process is complex and changeable, and different production factors can cause pinhole defects in the film layer. More than 40% of the defective rate in the mask substrate is directly related to the pinholes. The pinholes will cause holes in the film layer, causing light leakage in the film, causing diamond decoration, depression, serration, collapse and other defects in the product lines during the exposure and development process, which will bring a fatal blow to the production.

[0003] The current thin film formation method is the commonly used DC magnetron technology. The plane target forms the required film layer through AE DC power supply + process gas Ar, N2, O2, CO2 in different ratios. Common ways to control film layer pinholes include: controlling the cleanliness of the incoming base particles, the adhesion between the glass and the film layer, the cleanliness of the sputtering chamber, the clean treatment effect and surface roughness of the shielding, the selection of target material purity, and the gas distribution method of the process gas. The above methods can only remove most of the particles in the sputtering process, and some particles will form pinholes, resulting in product NG.

[0004] When the sputtering chamber is not properly sanitized, many pinholes will also appear in the film layer, resulting in a significant decrease in yield. Pinholes are also greatly affected by other factors. Since Ar and N2 are mainly ignition gases for bright chrome layer and oxide layer, when CO2 is excessively reduced, the corrosion resistance of the film layer will be significantly reduced.

[0005] Based on this, it is expected to obtain an optimized process, optimize the film sputtering process, improve the quality of film formation, avoid particles generated during the sputtering process, and thus reduce pinhole defects. Find the most suitable sputtering process atmosphere ratio to improve the film formation rate, reduce film pinhole defects, and overcome the shortcomings of the existing technology. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the current method of controlling pinholes in mask film layers, the present invention provides a method for reducing pinholes in film layers, a film layer and a photomask substrate, which can optimize the film layer sputtering process, improve the quality of film layer formation and reduce pinhole defects.

[0007] To achieve the above objectives, the embodiments of the present invention adopt the following technical methods:

[0008] On the one hand, a method for reducing pinholes in a film layer is characterized in that the method comprises the following steps:

[0009] Step S1: forming a bright chromium layer by a magnetron sputtering process, wherein the process gas distribution method used in the magnetron sputtering process is Ar, N2 and CO2, wherein the Ar flow rate is 80-200 sccm; the CO2 flow rate is 0.1-5 sccm; and the N2 flow rate is 1-20 sccm.

[0010] It should be noted that in the technical solution described in the present invention, the bright chrome layer has the characteristic of high reflectivity, and the surface of the product film layer needs low reflectivity, so a layer of chromium nitride is plated on the bright chrome layer to reduce the reflectivity of the surface of the film layer. The film layer requires both low reflectivity and acid and alkali resistance, corrosion resistance, and uniformity, so it is necessary to add impurity gases N2 and CO2 to participate in the reaction. Among them, adjusting the proportion of CO2 and O2 has little effect on the pinholes in the film layer. N2 reacts with chromium to directly form a chromium nitride film layer on the glass.

[0011] It should be noted that in the technical solution described in the present invention, Ar and chromium do not participate in the reaction, and a chromium film layer is directly formed on the glass. However, the pure chromium film layer has poor acid resistance, corrosion resistance and uniformity, so impurity gases N2 and CO2 need to be added to participate in the reaction.

[0012] When the CO2 setting value is greater than 5sccm, a batch of carbonized particles will appear in the bright chrome layer, causing pinhole defects, which directly leads to NG of batch products. Controlling the CO2 setting value during sputtering of the bright chrome layer can effectively control particles and pinhole defects.

[0013] There is no obvious change in the film particles by increasing or decreasing the N2, but too much nitrogen will cause the film to have extremely poor light shielding properties. The nitrogen setting is controlled at 1-20sccm, which can be set based on the customer's corrosion resistance requirements.

[0014] Step S2: forming an oxide layer on the bright chromium layer obtained in step S1 by using a magnetron sputtering process to obtain a film layer.

[0015] Preferably, in step S1, the process parameters are: body vacuum ≤ 1.0*10-3Pa; sputtering gas pressure 0.1-0.4Pa; sputtering power adopts 10kwAE power supply.

[0016] Preferably, in step S2, the process parameters are: body vacuum ≤ 1.0*10-3Pa; sputtering gas pressure 0.1-0.5Pa; sputtering power adopts 10kwAE power supply.

[0017] Preferably, in the step S2, the process gas distribution method used in the magnetron sputtering process is N2, O2 and CO2, wherein the N2 flow rate is 80-200 sccm; the CO2 flow rate is 1-15 sccm; and the O2 flow rate is 1-15 sccm.

[0018] Preferably, the method further comprises a pre-processing step before step S1, and the pre-processing step comprises one or more of the following operations:

[0019] Operation 1: Perform dust-free cleaning on the sputtering chamber and installed shielding;

[0020] Operation 2: The sputtering process uses a process gas with a purity of more than 99.999%.

[0021] Operation 3: The target material purity is 3N5 or above, preferably 5N.

[0022] Operation 4: The sputtering pressure value in the production process of the sputtering process is controlled to be 0.1~1.0Pa.

[0023] This type of cavity sputtering material control can significantly improve the final film quality of sputtering. This is because: the cavity material contamination of the coating machine itself will produce a batch of pinhole defects in the sputtering process, and controlling the cavity sputtering material can significantly improve the pinhole defects.

[0024] By controlling the sputtering pressure, the film forming efficiency and film adhesion of the film layer of the photomask substrate can be ensured.

[0025] In a second aspect, a film layer with few pinholes is provided, characterized in that the film layer is prepared by the method described in any one of the above schemes.

[0026] Preferably, the film layer includes a bright chrome layer and an oxide layer, wherein the thickness of the oxide layer is 50 to 300 Å.

[0027] Preferably, the pinhole diameter of the film layer is ≤10 μm, and the number of pinholes is ≤5.

[0028] Preferably, the thickness of the film layer can be changed according to demand by matching the deposition rate in power and travel speed.

[0029] In a third aspect, a photomask substrate is provided, characterized in that the photomask substrate comprises a glass substrate and a film layer attached to the glass substrate, and the film layer is prepared by a method for reducing pinholes in a film layer and any one of its preferred embodiments.

[0030] Compared with the prior art, the technical solution of the present invention has the following advantages and beneficial effects:

[0031] The present invention discloses a method for reducing pinholes in a film layer, a film layer, and a photomask substrate. By precisely controlling parameters such as the process gas flow rate, the number of pinholes in the film layer is effectively reduced, and the quality of the film layer formation is improved, so that the film layer has good characteristics such as low reflectivity, acid and alkali resistance, corrosion resistance, and uniformity. The sputtering process of the film layer is optimized through a variety of pre-treatment steps and parameter control, thereby improving the performance of the film layer, avoiding the occurrence of defects such as broken lines, depressions, white defects, and jagged edges in the product, and effectively improving the qualified rate and use effect of high-end quartz products. In particular, by controlling the proportion of CO2 used in the bright chrome layer, the generation of bright chrome layer particles is greatly reduced, and the occurrence of abnormal particles on the surface of the entire plate is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 The distribution diagram of atmosphere composition of the sputtered film layer of the photomask substrate according to the present invention in one embodiment;

[0034] Figure 2 This is a pinhole detection diagram of the sputtered film layer of the photomask substrate described in the present invention under the implementation of excessive CO2.

[0035] Figure 3 This is a pinhole detection diagram of the sputtered film layer of the photomask substrate described in the present invention under the implementation mode of CO2 being controlled.

[0036] Reference numerals: 1, oxide layer; 2, bright chrome layer; 3, glass substrate. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Figure 1 This is a distribution diagram of the atmosphere composition of the sputtered film layer of the photomask substrate described in the present invention in one embodiment; the photomask substrate includes an oxide layer 1, a bright chrome layer 2, and a glass substrate 3 from top to bottom, wherein the main gas compositions when the oxide layer 1 is sputtered are N2, CO2, and O2; the main gas compositions when the bright chrome layer 2 is sputtered are Ar, N2, and CO2.

[0039] Embodiment 1 comprises the following steps:

[0040] Step S1: A bright chromium layer is formed by a magnetron sputtering process, wherein the process gas distribution method used in the magnetron sputtering process is Ar, N2 and CO2, wherein the Ar flow rate is 80-200sccm; the CO2 flow rate is 0.1-5sccm; the N2 flow rate is 1-20sccm; the process parameters are body vacuum ≤1.0×10-3Pa; the sputtering gas pressure is 0.1-0.4Pa; and the sputtering power adopts a 10kwAE power supply.

[0041] Step S2: forming an oxide layer on the bright chrome layer obtained in step S1 by magnetron sputtering process, that is, obtaining a film layer, wherein the process gas distribution method used in the magnetron sputtering process is N2, O2 and CO2, wherein the N2 flow rate is 80-200sccm; the CO2 flow rate is 1-15sccm; the O2 flow rate is 1-15sccm. The process parameters are: body vacuum ≤1.0×10-3Pa; sputtering gas pressure 0.1-0.5Pa; sputtering power uses 10kwAE power supply.

[0042] In addition, a pre-processing step is also included before step S1, and the pre-processing step includes one or more of the following operations:

[0043] Operation 1: Perform dust-free cleaning on the sputtering chamber and installed shielding;

[0044] Operation 2: The sputtering process uses process gas with a purity of more than 99.999%;

[0045] Operation 3: The target material purity is 3N5 or above, preferably 5N;

[0046] Operation 4: The sputtering pressure value in the production process of the sputtering process is controlled to be 0.1~1.0Pa.

[0047] The above method can obtain a film layer with few pinholes, which includes a bright chrome layer and an oxide layer, wherein the thickness of the oxide layer is 50-300 Å. The pinhole diameter of the film layer is ≤10 μm, and the number of pinholes is ≤5.

[0048] A photomask substrate can be obtained from the above film layer, and the photomask substrate includes a glass substrate and the film layer attached to the glass substrate.

[0049] The steps of Examples 2 to 18 are the same as those of Example 1, but the parameter values ​​of the two are different, see Table 1 for details.

[0050] Table 1.

[0051]

[0052]

[0053]

[0054] The methods of Comparative Examples 1 to 3 are the same as those of Example 1, and the specific differences in parameters are shown in Table 2.

[0055] Table 2.

[0056]

[0057] In Comparative Example 1, when other conditions are the same as those in Example 1, the nitrogen flow rate is increased, and the bright chrome layer of the photomask substrate finally formed has poor quality and low light transmittance OD, which has an adverse effect on the photolithography process and leads to poor exposure effects, such as insufficient light energy received by the photoresist and blurred line edges.

[0058] In Comparative Example 2, Figure 2 As shown in the figure, when other conditions are the same as those in Example 1, the CO2 flow rate is increased, and particles appear on the entire film layer of the photomask substrate. This will cause defects in the photomask pattern, such as circuit line interruption, blurred pattern edges, and reduced resolution; it will also cause uneven exposure in the photolithography process, because particles change the light propagation path and absorb light, causing problems such as uneven thickness and pattern deformation after the photoresist is developed. By comparison Figure 2 and Figure 3 It can be seen that controlling the setting value of CO2 during sputtering of the bright chrome layer can effectively control particles and pinhole defects.

[0059] In Comparative Example 3, under the same conditions as in Example 1, the sputtering pressure was increased, and the density of the photomask substrate film layer finally formed became poor. Poor density will change the optical properties of the photomask, causing light scattering to reduce the optical resolution and blur the pattern. At the same time, it will lead to reduced mechanical stability of the film layer, reduced strength of the film layer structure, and prone to scratches, cracks and other damage.

[0060] The film layers obtained in Examples 2 to 18 were verified, and it was found that the pinholes in the film layers of Examples 2 to 18 were ≤10um, and the number was only 0 to 5. This is because: the pinholes in the film layer are mainly affected by the bright chrome layer. When the setting value of the sputtering CO2 flow rate of the bright chrome layer is controlled below 5sccm, the film layer particles will not show abnormal particles in the whole plate with a 5-inch substrate as the test sample. After the substrate passes through the IPA cleaning machine, the number of pinholes ≤10um is only 0 to 5.

[0061] The present invention discloses a method for reducing pinholes in a film layer, a film layer, and a photomask substrate. By precisely controlling parameters such as the process gas flow rate, the number of pinholes in the film layer is effectively reduced, and the quality of the film layer formation is improved, so that the film layer has good characteristics such as low reflectivity, acid and alkali resistance, corrosion resistance, and uniformity. The sputtering process of the film layer is optimized through a variety of pre-treatment steps and parameter control, thereby improving the performance of the film layer, avoiding the occurrence of defects such as broken lines, depressions, white defects, and jagged edges in the product, and effectively improving the qualified rate and use effect of high-end quartz products. In particular, by controlling the proportion of CO2 used in the bright chrome layer, the generation of bright chrome layer particles is greatly reduced, and the occurrence of abnormal particles on the surface of the entire plate is avoided.

[0062] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for reducing pinholes in a film layer, characterized in that: The method comprises the following steps: Step S1: forming a bright chromium layer by a magnetron sputtering process, wherein the process gas distribution method used in the magnetron sputtering process is Ar, N2 and CO2, wherein the Ar flow rate is 80-200 sccm; the CO2 flow rate is 0.1-5 sccm; and the N2 flow rate is 1-20 sccm; Step S2: forming an oxide layer on the bright chromium layer obtained in step S1 by using a magnetron sputtering process to obtain a film layer.

2. The method according to claim 1, characterized in that In step S1, the process parameters are: body vacuum ≤ 1.0×10 -3 Pa; sputtering gas pressure 0.1~0.4Pa; sputtering power adopts 10kwAE power supply.

3. The method according to claim 1, characterized in that In step S2, the process parameters are: body vacuum ≤ 1.0×10 -3 Pa; sputtering gas pressure 0.1~0.5Pa; sputtering power adopts 10kwAE power supply.

4. The method according to claim 1, characterized in that: In the step S2, the process gas distribution method used in the magnetron sputtering process is N2, O2 and CO2, wherein the N2 flow rate is 80-200 sccm; the CO2 flow rate is 1-15 sccm; and the O2 flow rate is 1-15 sccm.

5. The method according to any one of claims 1 to 4, characterized in that: The method further includes a pre-processing step before step S1, and the pre-processing step includes one or more of the following operations: Operation 1: Perform dust-free cleaning on the sputtering chamber and installed shielding; Operation 2: The sputtering process uses process gas with a purity of more than 99.999%; Operation 3: The target material purity is 3N5 or above; Operation 4: The sputtering pressure value in the production process of the sputtering process is controlled to be 0.1~1.0Pa.

6. The method according to claim 5, characterized in that The target material purity is 5N.

7. A film layer with few pinholes, characterized in that: The film layer is prepared by the method according to any one of claims 1 to 6.

8. The film layer according to claim 7, characterized in that: The film layer includes a bright chrome layer and an oxide layer, wherein the thickness of the oxide layer is 50-300 Å.

9. The film layer according to claim 7, characterized in that: The pinhole diameter of the film layer is ≤10 μm, and the number of the pinholes is ≤5.

10. A photomask substrate, characterized in that: The photomask substrate comprises a glass substrate and a film layer attached to the glass substrate, and the film layer is prepared by the method according to any one of claims 1 to 6.

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