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CN-122013126-A - Chromium film for photomask and preparation method thereof

CN122013126ACN 122013126 ACN122013126 ACN 122013126ACN-122013126-A

Abstract

The invention relates to a chromium film for a photomask and a preparation method thereof, wherein the preparation method comprises the steps of preprocessing a substrate; depositing a transition layer on the pretreated substrate, performing oxygen-containing plasma interface activation on the transition layer, depositing a chromium main functional layer on the activated transition layer at low temperature and regulating stress to obtain a chromium film, and performing post-treatment to stabilize the chromium film structure and stress. The chromium film comprises a substrate, a chromium main functional layer and a transition layer, wherein the substrate is a support carrier of the chromium film, the chromium main functional layer is a carrier for realizing photoetching of a photomask, the chromium main functional layer is arranged on the substrate, the transition layer is configured to realize high combination and stress buffering of the substrate and the chromium main functional layer, and the transition layer is arranged between the substrate and the chromium main functional layer. The invention fundamentally reduces the film stress, realizes ultra-high binding force at ultra-low temperature, and synchronously improves the pattern precision and uniformity.

Inventors

  • ZHAO YUSONG

Assignees

  • 绍兴芯链半导体科技有限公司

Dates

Publication Date
20260512
Application Date
20260228

Claims (10)

  1. 1. A method for preparing a chrome film for a photomask, comprising: Depositing a transition layer on a substrate; Performing oxygen-containing plasma interface activation on the transition layer; Depositing a chromium main functional layer on the activated transition layer at low temperature and regulating stress to obtain a chromium film, and And (5) performing post-treatment to stabilize the chromium film structure and stress.
  2. 2. The method for producing a chrome film for photomask according to claim 1, wherein the substrate is a quartz substrate or a synthetic quartz glass.
  3. 3. The method for producing a chrome film for photomask according to claim 1, further comprising: And pre-treating the substrate before depositing the transition layer, wherein the pre-treatment comprises ultraviolet ozone cleaning, and in the ultraviolet ozone cleaning, the ultraviolet wavelength is 185nm/254nm and the irradiation time is 10-20 min.
  4. 4. The method for preparing a chrome film for a photomask according to claim 3, wherein the pretreatment further comprises low-power plasma cleaning, wherein in the low-power plasma cleaning, plasma is inert gas, power is less than or equal to 80W, air pressure is 0.3-0.5 pa, and cleaning time is 100-150 s.
  5. 5. The method of claim 1, wherein the transition layer is a CrON gradient transition layer, and/or Depositing a transition layer on a substrate includes: Introducing O 2 and N 2 , controlling the total flow to be 30-50 sccm, controlling the working pressure to be 0.2-0.4 Pa, adopting a Cr target, adopting sputtering power to be 1.5-2.5 kW, and adopting dynamic gas flow control to deposit a transition layer with the thickness of 5-8 nm in 60-70 seconds, wherein the flow ratio of O 2 to N 2 is gradually changed from initial (8-9): (1-2) to final (1-2): (8-9).
  6. 6. The method of claim 1, wherein performing oxygen-containing plasma interface activation on the transition layer comprises: Introducing Ar/N 2 /O 2 mixed gas, and And performing plasma treatment under the conditions of 0.3-0.5 Pa and 55-60W.
  7. 7. The method for producing a chromium film for a photomask according to claim 6, wherein the volume ratio of Ar/N 2 /O 2 is (85-90): (9-13): (1-2), and the plasma treatment time is 40-50 seconds.
  8. 8. The method of claim 1, wherein depositing a chromium main functional layer on the activated transition layer at a low temperature and controlling stress comprises: Depositing a chromium main functional layer at a low temperature by adopting an unbalanced magnetron sputtering technology, wherein the target power in the chromium main functional layer is 2.0-3.0 kW, the substrate temperature is constant at 75-80 ℃, and Applying a DC bias voltage to the substrate, wherein the DC bias voltage is-50 to-60V so as to regulate and control the stress of the chromium film in real time, and/or The thickness of the chromium film is 80-90 nm.
  9. 9. The method for preparing a chrome film for a photomask according to claim 1, wherein the post-treatment comprises: and (3) carrying out low-temperature annealing treatment on the chromium film in a vacuum environment, wherein the vacuum degree is less than or equal to 1 multiplied by 10 -3 Pa, the annealing temperature is 150-170 ℃ and the annealing time is 20-30 min in the low-temperature annealing treatment.
  10. 10. A chromium film, comprising: A substrate which is a support carrier for the chromium film; a chromium main functional layer as a carrier for photo mask lithography, the chromium main functional layer being provided on the substrate, and A transition layer configured to achieve high bonding and stress buffering of the substrate and the chromium primary functional layer, the transition layer disposed between the substrate and the chromium primary functional layer, and/or The transition layer is a CrON gradient transition layer.

Description

Chromium film for photomask and preparation method thereof Technical Field The invention relates to the technical field of semiconductor manufacturing, relates to a chromium film for a photomask and a preparation method thereof, and in particular relates to a low-stress chromium film for the photomask and a preparation method thereof. Background In the field of semiconductor manufacturing, deep Ultraviolet (DUV) lithography (such as ArF 193nm and KrF 248nm lithography) is a core process of a very large scale integrated circuit (vlsi) process, a binary photomask is used as a key precision template in the photolithography process, and the preparation quality of a light-shielding chromium film directly determines the line width uniformity, edge roughness and positioning accuracy of a photolithography pattern, which has a decisive influence on the yield and performance of the chip process. In the manufacture of binary photomasks, the chromium film used as a light shielding layer has the specific defects that 1) the pattern is locally distorted, and because high residual compressive stress (usually-400 MPa to-600 MPa) exists in the chromium film, the stress is unevenly released after patterning, so that nano-scale local distortion (Micro-deposition) is generated on the photoetching pattern, the fidelity and overlay accuracy of photoetching imaging are directly influenced, 2) the uniformity of the line width is poor, the uneven stress distribution and the insufficient binding force between the film layer and a quartz substrate can cause unpredictable microscopic change of the line width of the pattern in the processes of repeated cleaning and laser repairing, and the line width uniformity (CDU) of the whole mask exceeds the strict specification of a binary process (such as a node of <5 nm), and 3) the process window conflicts, namely, the stress is increased for improving the binding force, the deposition rate is slowed down for reducing the stress, the production efficiency and the compactness of the film layer is sacrificed. The traditional process is difficult to balance among high binding force, low stress and high productivity. Disclosure of Invention The invention provides a chromium film for a photomask and a preparation method thereof, in particular to a low-stress chromium film for a photomask and a preparation method thereof, which are used for fundamentally reducing the stress of a film layer, stably controlling the intrinsic stress of the chromium film at a low level (the target range is-100 MPa to +50 MPa), eliminating the main cause of local distortion of a pattern from the source, realizing ultra-high binding force at ultra-low temperature and synchronously improving the pattern precision and uniformity. The first aspect of the present invention provides a method for preparing a chrome film for a photomask, comprising: pretreating a substrate; depositing a transition layer on the pretreated substrate; Performing oxygen-containing plasma interface activation on the transition layer; Depositing a chromium main functional layer on the activated transition layer at low temperature and regulating stress to obtain a chromium film, and And (5) performing post-treatment to stabilize the chromium film structure and stress. Further, the substrate is a quartz substrate or synthetic quartz glass. Further, the pretreatment comprises ultraviolet ozone cleaning, wherein in the ultraviolet ozone cleaning, the ultraviolet wavelength is 185nm/254nm, and the irradiation time is 10-20 min. Further, the pretreatment further comprises low-power plasma cleaning, wherein in the low-power plasma cleaning, the plasma is inert gas, the power is less than or equal to 80W, the air pressure is 0.3-0.5 Pa, and the cleaning time is 100-150 s. Further, the transition layer is a CrON gradient transition layer, and/or Depositing a transition layer on the pretreated substrate comprises: Introducing O 2 and N 2, controlling the total flow to be 30-50 sccm, controlling the working pressure to be 0.2-0.4 Pa, adopting a Cr target, adopting sputtering power to be 1.5-2.5 kW, and adopting dynamic gas flow control to deposit a transition layer with the thickness of 5-8 nm in 60-70 seconds, wherein the flow ratio of O 2 to N 2 is gradually changed from initial (8-9): (1-2) to final (1-2): (8-9). Further, the transition layer is a CrON gradient transition layer in which the composition continuously changes from oxygen enrichment to nitrogen enrichment on the side contacting the substrate in the thickness direction, and the nitrogen enrichment state is on the side contacting the chromium main functional layer. Further, performing oxygen-containing plasma interface activation on the transition layer comprises: Introducing Ar/N 2/O2 mixed gas, and Performing plasma treatment under the conditions of 0.3-0.5 Pa and 55-60W; Further, the volume ratio of Ar/N 22/O22 is (85-90): 9-13): 1-2, and the plasma treatment time is 40-50 seconds. Further, depo