Browse Prior Art Database

Shadow Projection Mask and Method of Producing Same

IP.com Disclosure Number: IPCOM000044086D
Original Publication Date: 1984-Nov-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Behringer, U: AUTHOR [+5]

Abstract

The mask has transparent pattern elements consisting of a screen allowing the transfer of annular pattern elements by using a single mask instead of two complementary masks. To form the screen in the mask material, tracks are generated by irradiation with high-energy heavy ions (e.g., Xe+, 10 MeV) and subsequently developed by etching. The mask is formed from a silicon wafer 1 having a boron-doped Psurface layer 2. Onto layer 2, a high-resistance epitaxial layer 3 is deposited. Wafer 1 is selectively thinned from the backside in the areas where the mask pattern is to be generated in a subsequent step. Layer 2 serves as an etch stop. Fig. 1 shows a cross-section of the areas at this stage. Holes 4, corresponding to the mask pattern, are etched into layer 3. As shown in Fig. 2, holes 4 do not penetrate layer 3 completely.

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Shadow Projection Mask and Method of Producing Same

The mask has transparent pattern elements consisting of a screen allowing the transfer of annular pattern elements by using a single mask instead of two complementary masks. To form the screen in the mask material, tracks are generated by irradiation with high-energy heavy ions (e.g., Xe+, 10 MeV) and subsequently developed by etching. The mask is formed from a silicon wafer 1 having a boron-doped Psurface layer 2. Onto layer 2, a high-resistance epitaxial layer 3 is deposited. Wafer 1 is selectively thinned from the backside in the areas where the mask pattern is to be generated in a subsequent step. Layer 2 serves as an etch stop. Fig. 1 shows a cross-section of the areas at this stage. Holes 4, corresponding to the mask pattern, are etched into layer 3. As shown in Fig. 2, holes 4 do not penetrate layer 3 completely. Then, blanket irradiation is performed, using heavy ions for forming tracks in the high-resistance material of layer 3. An etch mask 6 of a heat-resistant material, such as tungsten, is generated on layer 3, for example, by inclined evaporation, in order to avoid the deposition of the heat-resistant material at the bottom of holes 4. The heavy ion tracks in holes 4 are developed by etching (Fig. 3) for forming the tubes 5. In the subsequent heat treatment step, part of the boron in layer 2 is diffused into layer 3, in order to prevent electrostatic charges during electron beam exposure and in ord...