0. Table of contents. Author: Wim Talen

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1 Document nr. : WimTal V03 Page nr. : 0 Document : Operation Manual KOH-etch Epcode : Administrator : Documents Administrator TFF Date : Author: Wim Talen 0. Table of contents 0. Table of contents Changes compared to previous versions Safety General Chemicals General information Operation manual General Operating Procedure Process Control Rules & Regulations Instruction and test... 6

2 Document nr. : WimTal V03 Page nr. : 1 Document : Operation Manual KOH-etch Epcode : 1. Changes compared to previous versions Date Page number New version number Description /01 First version /02 Second version /03 Third version

3 Document nr. : WimTal V03 Page nr. : 2 Document : Operation Manual KOH-etch Epcode : 2. Safety 2.1 General First Aid Measures General Remove contaminated clothing, wash thoroughly before use. Eye Contact Immediately flush eyes with plenty of water for at least 15 minutes, Lifting lower and upper eyelids occasionally. Get medical attention immediately.. Skin Contact In case of contact, immediately flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Get medical attention immediately. Ingestion If swallowed, DO NOT INDUCE VOMITING. Give large quantities of water. Get medical attention immediately. Inhalation Remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention immediately. 2.2 Chemicals Potassium Hydroxide Solution 30% Selectipur* Use: process chemical Company: BASF SE Ludwigshafen GERMANY CAS Number: EC-Number: INDEX-Number: Hazard symbol(s): C Corrosive. R-phrase(s): 22 Harmful if swallowed. 35 Causes severe burns. Detailed information about these chemicals can be found in the corresponding Material Safety Data Sheets (MSDS). potasium%20hydroxide%20solution%2030pct.pdf

4 Document nr. : WimTal V03 Page nr. : 3 Document : Operation Manual KOH-etch Epcode : 3. General information KOH isotropic wet chemical etching remains the most widely used processing technique in silicon technology. It is used for the removal of mono crystalline or polycrystalline silicon. Used in combination with a multitude of other processes, it has a wide range of applications in micro electromechanical systems (MEMS). Its wide presence is not only due to its ease of use and low cost, but also due to the fact that it provides fairly smooth surfaces with no physical damage to the bulk. All KOH isotropic etches attack the substrate preferentially. That means, they etch at a higher rate in certain directions than they do in others, The KOH process is used because of its repeatability and uniformity in fabrication. The most important parameters in chemical etching are Under etch Tolerance Etch rate Anisotropy Selectivity Over etch. Processconditions KOH: 10 Liter concentration 30% (mass percentages). Temp. KOH: 72 C (the thermo baths are set to 80 C)! Chemical overall reaction Si + 2OH - + 2H 2 O SiO 2 (OH) H 2 4. Operation manual 4.1 General Substrate handling for KOH etch bad 100mm quartz rack, 7 slots, for 100mm wafers 150mm quartz rack, 7 slots, for 150mm wafers 200mm quartz rack, 7 slots, for 200mm wafers Also more robust Teflon racks are available

5 Document nr. : WimTal V03 Page nr. : 4 Document : Operation Manual KOH-etch Epcode : Quartz-Rack 4.2 Operating Procedure - Check magnetic stirrer and the temperature / timer in front of LFB are on. - Check the temperature of the thermo water heater in the maintenance corridor. - Place your substate(s) in the KOH. The cooled lid prevents evaporation of KOH and should always be placed on the vessel. - After etching, rinse you substate in the water bath in the middle of the LFB. - After this step it is up to the operator to decide if a dip in the 5% HCl bath is necessary, if so a water rinse should also follow the HCl rinse. - After use dry the carrier and place it back on the shelf. Clean and dry the LFB.

6 Document nr. : WimTal V03 Page nr. : 5 Document : Operation Manual KOH-etch Epcode : 5. Process Control In the past we decided to stop process control because this did not give additional information. There is a diversity of processes and substrates. This makes testing and in between checks necessary. 6. Rules & Regulations Use of baths is not allowed without authorization of the equipment owner. Before use inform yourself on possible danger (study MSDS, see Protect yourself with gloves and glasses. Do not move filled dishes. Keep tools like carriers together with the bath where they prolong to. While rinsing carrier and substrate with water also spray the handle. Save water, shut down after use. After use place carriers back dry on the shelves. Clean up your working space after use (remove tools out of the LFB). Remove waste chemicals according the correct way. In case of questions or in case of doubt always contact the equipment owner and / or his backup.

7 Document nr. : WimTal V03 Page nr. : 6 Document : Operation Manual KOH-etch Epcode : 7. Instruction and test The only person, who is allowed to carry out the instruction, is the equipment owner or backup. Normally the instruction will take about half an hour and will be given only after reading this manual. First the construction and possibilities of the wet bench will be explained with respect to the various chemicals. The correct way to run this process will be explained on the basis of the Operating Manual as described in chapter 4.