Dry development rinse process (DDRP) and material (DDRM) for novel pattern collapse free process

Abstract

Because the pattern pitch is getting smaller and smaller, the pattern collapse issue in the lithography process have been getting the sever problem. Especially, pattern collapse is one of the main reasons for minimizing of process margin at fine pitch by EUV lithography. The possible major cause of pattern collapse is the surface tension of the rinsing liquid and the shrinkage of resist pattern's surface in the process of drying the rinsing liquid. The influence of surface tension for very small pitch pattern is particularly severe. The one of the most effective solution for this problem is thinning of the resist film thickness, however this method is reaching to its limits in terms of substrate etching process anymore. The tri-layer resist process or hard mask processes have been used, but there is a limit to the thinning of resist film and there is no essential solution for this problem. On the other hand, the supercritical drying method has been known as an ultimate way to suppress the pattern collapse issue. The supercritical drying method is a dry process advanced to the vapor phase from the liquid phase via supercritical, and the supercritical drying method can dry the rinsing liquid without making the vapor-liquid coexistence state. However, this process is not applied to the mass production process because it requires the introduction of the special equipment. We newly developed the novel process and material which can prevent the pattern collapse issue perfectly without using any special equipment. The process is Dry Development Rinse Process (DDRP), and the material used in the process is Dry Development Rinse Material (DDRM). DDRM is containing the special polymer which can replace the exposed and developed part. And finally, the resist pattern will be developed by Dry etching process without any pattern collapse issue. In this paper, We will discuss the approach for preventing the pattern collapse issue in PTD and NTD process, and propose DDRP and DDRM as the solution.Key word : Pattern collapse, Supercritical drying method, Dry development rinse process(DDRP), Dry development rinse material (DDRM)

Interfacial effects on sensitization of chemically amplified extreme ultraviolet resists

“…9) With the reduction of pitch, the pattern collapse is induced by the surface tension of the rinsing liquid. [10][11][12][13] The aspect ratio of resist patterns in line-and-space patterns is generally kept at approximately less than 2 to avoid pattern collapse. Therefore, the thickness will be decreased to 16 nm at the pitch of 16 nm.…”

A bottom-up pattern collapse mitigation strategy for EUV lithography

“…The most common pattern collapse mitigation strategies (reducing resist thickness, optimized resist adhesion, low surface tension rinse liquid, critical point drying) have been employed to their limits and novel and effective techniques are in high demand. Recently, promising results have been achieved by avoiding the drying step in wafer processing by encapsulating the resist structures in a polymer film while they are still wet [11,16]. However, these top-down techniques increase the number of device fabrication process steps and hence the overall cost.…”

“…Another technique for removal of the capillary forces, "dry develop rinse process" (DDRP), has been introduced recently [11]. The technique has been proven to be effective in mitigating pattern collapse while being compatible with highvolume manufacturing.…”

“…Sakamoto et al applied the DDRP process to organic resists [11], which are the workhorse of current high-volume electronics manufacturing. While organic resists, especially CARs, are under further development for use in future semiconductor fabrication nodes [4,13] inorganic resists have recently emerged as a realistic alternative for high-volume manufacturing due to their improved sensitivity, resolution, line-edge roughness, and high etch-resistance [14][15].…”

Toward 10 nm half-pitch in extreme ultraviolet lithography: results on resist screening and pattern collapse mitigation techniques

“…15 In this process, lithography is carried out as usual until the rinsing after development. 15 In this process, lithography is carried out as usual until the rinsing after development.…”