Method for increasing washability of photomask

Abstract

The invention relates to a method for increasing the washability of a photomask, which comprises the following steps of: respectively adding an oxygen plasma treatment process at the end of an exposure development process and a photoresist removal process so as to form an oxidation protection layer on the surface of a pattern, and replacing MoO2 with relatively low bond energy into MoO3 with relatively high bond energy, so that the washability of the photomask is improved. And the oxidation protection layer is additionally arranged on the Cr layer, so that the washability of the photomask is greatly improved, and the influence of cleaning on the size and phase of the photomask is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of photomasks, and in particular to a method for increasing the washability of photomasks. Background Art

[0002] As the design of mask patterns becomes more and more complex and precise, in order to achieve exposure focal depth to effectively expose the wafer photoresist, 193nm exposure wavelength and ArF-PSM (phase shift mask) mask materials have also begun to be widely used. Due to the change in exposure wavelength energy and materials, growth-type haze defects begin to appear and affect chip yields. Therefore, when growth-type haze defects occur, chip factories will choose to send the mask for repair and cleaning. At this time, the washability of the mask becomes an important factor affecting its service life. Summary of the invention

[0003] The present invention aims to provide a method for increasing the washability of a photomask, so as to improve the washability of the photomask.

[0004] The specific plan is as follows:

[0005] A method for increasing the washability of a photomask comprises the following steps:

[0006] S1, providing a photomask substrate, the substrate having a MoSi layer, the MoSi layer covered with a Cr layer, and forming a photomask pattern on the substrate through pattern drawing and exposure and development processes, and the pattern is also covered with a photoresist;

[0007] S2, using a plasma treatment device to perform oxygen plasma treatment on the pattern of the mask, and forming an oxide layer corresponding to the MoSi layer and the Cr layer on the side wall of the mask pattern through the oxygen plasma treatment process;

[0008] S3. Remove the photoresist on the pattern, and after the photoresist is removed, use a plasma treatment device to perform oxygen plasma treatment on the pattern of the mask, so that an oxide layer corresponding to the MoSi layer and the Cr layer is formed on the surface of the mask pattern and the oxide layer on the side wall of the mask pattern is thickened through the oxygen plasma treatment process, and MoO2 is replaced by MoO3.

[0009] Furthermore, the oxygen plasma treatment process in step S2 is as follows: the discharge power is 200-300 W, the oxygen flow rate is 10-20 mL / min, and the treatment time is 20-40 min.

[0010] Furthermore, the oxygen plasma treatment process in step S3 is as follows: the discharge power is 200-300 W, the oxygen flow rate is 10-20 mL / min, and the treatment time is 20-40 min.

[0011] The method for increasing the washability of the mask provided by the present invention has the following advantages compared with the prior art: the method for increasing the washability of the mask provided by the present invention adds an oxygen plasma treatment process at the end of the exposure and development process and the photoresist removal process, respectively, to form an oxidation protective layer on the surface of the pattern, and replaces the original MoO2 with lower bond energy with MoO3 with higher bond energy, thereby avoiding the bond breaking and migration of molybdenum ions during the mask exposure process and increasing the oxidation protective layer on the Cr layer. Due to the increase of the oxidation protective layer, the washability of the mask will be greatly improved, thereby reducing the impact of cleaning on the mask size and phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of the oxygen plasma process is shown. DETAILED DESCRIPTION

[0013] To further illustrate the various embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0014] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0015] The present invention provides a method for increasing the washability of a photomask, which is aimed at ArF-PSM (phase shift mask) photomasks. In the production process, an oxygen plasma process is added to form an oxidation protection layer on the surface of the PSM photomask pattern. Due to the addition of the oxidation protection layer, the washability of the photomask will be greatly improved, thereby reducing the impact of cleaning on the size and phase of the photomask. Figure 1 The specific implementation of this method includes the following steps:

[0016] S1, providing a photomask substrate 1, the substrate 1 has a MoSi layer 2, the MoSi layer 2 is covered with a Cr layer 3, and after pattern drawing and exposure and development processes, a Cr layer 3 is formed. Figure 1 The structure shown in the figure is also covered with a photoresist 4. It should be noted that the substrate 1 is usually made of quartz glass, and the MoSi layer 2 and Cr layer 3 are formed on the substrate, as well as the pattern drawing, exposure and development processes are all existing technologies, and the specific process technology will not be described in detail here.

[0017] S2. After the exposure and development process is completed, the pattern of the mask is treated with oxygen plasma using a plasma treatment device. The specific process is as follows: the discharge power is 200-300W, the oxygen flow rate is 10-20mL / min, and the treatment time is 20-40min. The oxide layer 5 corresponding to the MoSi layer 2 and the Cr layer 3 is formed on the side wall of the mask pattern through the oxygen plasma treatment process.

[0018] S3. Remove the photoresist 4 on the pattern. The process for removing the photoresist 4 is a prior art, and the specific process technology is not described in detail here. After the photoresist 4 is removed, the pattern of the mask is treated with oxygen plasma using a plasma treatment device. The specific process is as follows: the discharge power is 200-300W, the oxygen flow rate is 10-20mL / min, and the treatment time is 20-40min. Through the oxygen plasma treatment process, an oxide layer 5 corresponding to the MoSi layer 2 and the Cr layer 3 is formed on the surface of the mask pattern, and the oxide layer 5 on the side wall of the thickened mask pattern is thickened, and the original MoO2 with a lower bond energy is replaced with MoO3 with a higher bond energy, so as to avoid the bond breaking migration of molybdenum ions during the mask exposure process, so as to increase the service life of the mask and improve its washability.

[0019] The method for increasing the washability of the mask provided by the present invention adds an oxygen plasma treatment process at the end of the exposure and development process and the photoresist removal process, respectively, to form an oxidation protection layer on the surface of the pattern, replacing the original MoO2 with lower bond energy with MoO3 with higher bond energy, avoiding the bond breaking and migration of molybdenum ions during the mask exposure process and increasing the thickness of the oxidation protection layer on the Cr layer. Due to the increase of the oxidation protection layer, the washability of the mask will be greatly improved, thereby reducing the impact of cleaning on the mask size and phase.

[0020] The method provided by the present invention can increase the washability of the photomask by comparing the examples. Sample 1 is a photomask product made by the existing process, and sample 2 is a product made by the method provided by the present invention. The difference between the two is that sample 2 adds an oxygen plasma treatment process at the end of the exposure and development process and the photoresist removal process, and the other process parameters are the same as sample 1. The photomask is cleaned ten times and the size and phase changes of the photomask are confirmed. The size and phase changes of sample 2 are reduced by two times compared with sample 1. This proves that the photomask after the oxygen plasma treatment process can withstand more cleaning times than the general photomask, thereby improving the washability of the photomask.

[0021] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A method for increasing the washability of a photomask, It is characterized in that The following steps are involved: S1, providing a photomask substrate, the substrate having a MoSi layer, the MoSi layer covered with a Cr layer, and forming a photomask pattern on the substrate through pattern drawing and exposure and development processes, and the pattern is also covered with a photoresist; S2, using a plasma treatment device to perform oxygen plasma treatment on the pattern of the mask, and forming an oxide layer corresponding to the MoSi layer and the Cr layer on the side wall of the mask pattern through the oxygen plasma treatment process; S3, removing the photoresist on the pattern, and after removing the photoresist, performing oxygen plasma treatment on the pattern of the photomask using a plasma treatment device, forming an oxide layer corresponding to the MoSi layer and the Cr layer on the surface of the photomask pattern and thickening the oxide layer on the side wall of the photomask pattern through the oxygen plasma treatment process, and making the MoO 2 Replaced by MoO 3 .

2. The method according to claim 1, It is characterized in that The oxygen plasma treatment process in step S2 is as follows: the discharge power is 200-300 W, the oxygen flow rate is 10-20 mL / min, and the treatment time is 20-40 min.

3. The method according to claim 1, It is characterized in that The oxygen plasma treatment process in step S3 is as follows: the discharge power is 200-300 W, the oxygen flow rate is 10-20 mL / min, and the treatment time is 20-40 min.

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