Fabrication of Lateral Polysilicon Gap of Less than 50 nm Using Conventional Lithography

et al. 2013

AMR

For a submicron photolithography process, there is little room for error. In this paper, an optimized technique for photoresist (PR) development is reported, to fabricate a nanogap biosensor for application in biomedical nanodiagnostics. The pattern transfer on the wafer substrate requires precise alignment and Deep Ultra-Violet (DUV) light exposure. This research describes the photolithography process to develop a standard manufacturing procedure for pattern transfer from chrome mask. The key factor for PR development is understood and the optimization is done based on the PR thickness, spin speed, spin time, exposure time, post-exposure bake (PEB) time, developer concentration and developing time to achieve the design feature size of 1 micron. The PR is coated and spun at 3000 rpm and 5000 rpm at 30s and 40s respectively to form a very thin layer. However, the UV exposure time is remained constant at 10s. After the pattern transfer, the wafer is immersed in different concentrations of RD6 developer to develop the PR. To further improve the resolution of image transfer, the PEB time is also optimized for a better throughput on feature size. These optimizations are important to reduce the dimension error and were able to achieve error free design to protect critical dimension and prevent device failure.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Conventional Photolithography and Process Optimization of Pattern-Size Expansion Technique for Nanogap Biosensor Fabrication

Balakrishnan

Asri

et al. 2013

AMR

“…Based on its technical specifications, the resist could be used for 365 nm or 436 nm wavelength exposure. After coated with the PR, the wafer is soft baked on a hot plate (JB-TEK Honeywall) at 100ºC for 60s and then cooled down to room temperature [18]. The wafer is prepared for UV exposure using MIDAS Exposure System MDA-400M for pattern transfer as illustrated in fig.…”

Section: Pattern Transfermentioning

confidence: 99%

Pattern Transfer of 1μm Sized Microgap and Microbridge Electrode for Application in Biomedical Nano-Diagnostics

Balakrishnan

2014

AMR

We present a new design of biochip for application in clinical diagnostics by using a conventional method of pattern transfer process in microelectronic fabrication. Although there are many advanced techniques available to produce nanostructures such as electron beam lithography (EBL), ion-beam lithography (IBL), focused ion beam milling and nanoimprint lithography, these methods often requires high maintenance costs, time consuming and very complicated compared to conventional photolithography. This conventional technique is still a good choice for a feature size more than 1 micron. In this work, microbridge and microgap design from chrome mask are transferred on silicon wafer to fabricate a biochip. The pattern transfer of the first mask of electrode is presented in this paper to test the repeatability of pattern transfer during photolithography process. Therefore, during the process, the resolution and precise alignment factors are taken into account to prevent circuit and device failure. Post-exposure bake time and development limitations are recorded for both designs.

“…Although there are many advanced techniques available to produce nanostructures such as electron beam lithography (EBL), ion-beam lithography (IBL), focused ion beam milling and nano-imprint lithography, these methods often requires high maintenance costs, time consuming and very complicated compared to conventional photolithography [9]. This conventional technique is still a good choice for a feature size more than 1 micron.…”

Section: Introductionmentioning

confidence: 99%

Photoresist microbridge pattern optimization at 1μm using conventional photolithography technique

Rao

Nurfaiz

RSM 2013 IEEE Regional Symposium on Micro and Nanoelectronics

2013

Self Cite

One of the delicate processes in semiconductor microfabrication is the photolithography. It is the process that sets the design dimensions on various parts of the device. In order to complete this process, two requirements need to be satisfied. First is to create, the exact dimensions and pattern as established in design phase, which in other word can be referred as the resolution of the images on the wafer. The second is the correct placement of the device pattern on the wafer relative to the crystal orientation of the wafer substrate. This is called alignment or registration of patterns in correct position. This registration requirement is similar to the correct alignment of the different floors of a building. It is easy to visualize that misalignment of elevator shafts and stair wells would render the building useless. In a circuit, the effects of misaligned mask layers can cause the entire circuit to fail. In this paper we have reported a couple of results that leads to photoresist development and optimization technique as a standard manufacturing process to form 1μm microbridge for later process of size reduction to form nanogap. Therefore, at the final stage of fabrication, a nano-diagnostic biochip device is developed to use it as a biomolecule detection biosensor. The development of biosensors is still an open field and much remains to be done before many of these bioelectronic devices become commercialized. In this research, the key factors such as resist thickness, post-exposure bake (PEB) time and developer concentration are taken into account to study the optimum measurements and process. The thickness of resist will affect the resolution of image transferred and developing time. Both PEB and developer concentration also has the tendency to affect the device pattern and developing time. As the result, the photoresist thickness is optimized at 1500nm, the developer RD6 concentration diluted at 10:25 (DI water: RD6) and PEB time optimized at 65s.