Mask Aligner

In an usual manufacture process of devices or integrated circuits, the generation of a guide template which determines the geometry and dimensions of the microdevice is an important step. In medium and big scale device or integrated circuits productions, photomasks are employed which through photolithographic processes generate the patterns that are going to be exposed to different material films which allow to materialize our micrometric device.

Escritora de fotomáscaras HEIDELBERG uPG 101

Fig 1. Pattern generator HEIDELBERG uPG 101.

The pattern generator, or photomasks writer of the CIDESI Queretaro Microtechnology Management clean room, is an instrument that by the exposure to a laser with a 375nm wavelenght, is responsible of generating or record from 2D geometric patterns to 3D structures depending on the used resin, with a precission up to 4µm in exposure areas of up to 63 x 70 cm². Apart from providing tools as position measurements and alignments to perform superimposed exposures of several high precision layers. See Fig 1.

The apparatus is employed mainly for photomask generation for their later use in UV exposure and alignement apparatus. Nevertheless, the apparatus versatility allows to generate patterns directly on the substrate, commonly glass or silicon. See Fig 2.

Fig. 2. User performing a microrecording process.

Photomask aligner

Fig. 3. Finished photomask of micrometric devices.

The photomasks manufacture starts from a glass substrate with a stack coated with Chromium followed by a photosensitive resin. The mask writer through laser exposure in XY coordinates sensitizes the resin, which makes it soluble or insoluble to the revealer of its kind, depending on whether it is a positive or negative resin respectively. After the exposure (pattern recording) the revealing process is carried on where the soluble areas of the mask are removed generating exposed areas of chromium, these areas will be after chimically attacked, generating translucent windows where the light will pass through in the photolithographic processes. See Fig 3.

Fig. 4. Photomask design and manufacture.

Finally, the photomask is ready and can be used in future photolithographic processes, see Fig. 5. ¿Do you already know how they are done? you are invited to know them in the nextlink.

Fig. 5. Use of photomasks for electronic deivces manufacturing.

Direct etching over substrates

The versatility of this apparatus allows to generate patterns directly over substrates with a sensitive photoresin, generally this technique is used when concept proves are being done, initial prototypes of a development or simply unitary productions of devices. See Fig 6.

Fig. 6. Direct recording over substrates.

The procedure for recording over substrates follows the same technique as the photomask recording, however, depending on the type of material and selected processing the attacks over the exposed region without resin will differ a little. For more information visit the following link, about the photolithography process.

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