A 500 DPI FINGERPRINT SENSOR IC IN CMOS Wolfgang PRIBYL, Siemens EZM Ges.m.b.H., Graz-Villach, Austria Thomas SCHEITER, Siemens Semiconductor Division, Munich, Germany Gerd HRIBERNIG, Siemens PSE, Graz, Austria Keywords: biometrics, fingerprints, monolitiiic silicon sensor systems, CMOS, Complementary Metal Oxide Semiconductors, passwords, PIN codes, Personal identification Number codes, security systems, identification systems, identification devices, authorization, pattern recognition, chip cards Abstract: A monolithic fingerprint sensor has been implemented in a CMOS technology. This new sensor has a spatial resolution of 50 /jm and translates the fingerprint pattern into a gray scale image of 256 x 256 pixels with 8 bit resolution. The sensor chip measures about 160 mm"", together with a pattern recognition software, which extracts characteristic features, it forms a low cost system, which is well suited for a variety of applications as e.g. access control for buildings, computer networks and many other services. CMOS integrirano vezje za senzor prstnih odtisov z Ključne besede: biometrika, odtisi prstni, sistemi senzorjev silicijevih monolitnih, CMOS polprevodniki kovinskooksidni komplementarni, gesla, PIN kode številčne identifikacijske osebne, sistemi varnostni, sistemi identifikacijski, naprave identifikacijske, odobritev, razpoznavanje vzorcev, chip kartice Povzetek: Izdelali smo senzor prstnih odtisov v CMOS tehnologiji. Njegova prostorska ločljivost je 50 (.im pri prevajanju oblike prstnega odtisa v sivo sliko velikosti 256x256 pik z 8 bitno ločljivostjo. Površina senzorskega vezja je 160 mm^. Skupaj s programsko opremo za prepoznavanje oblik sestavlja sistem, katerega nizka cena omogoča različne uporabe, kot so nadzor vstopa v objekte, računalniške mreže in podobno. 1. Introduction For a long time keys, made from metal in a more or less sophisticated way, have been a well accepted measure to protect property and the private sphere of people and organizations. But these keys can be stolen or lost, copying of the keys may reduce the security or privacy level to zero. Besides those well known key systems, which are based on the possession of a key also knowledge based systems are used. These systems substitute the physical keys by agreements of secret codes. Many of today's systems as e.g. mobile phones, credit cards, computers require special passwords or PIN-codes (personal identification number). The ac- Iris 0.7^o lietina 1'^b , P.-nd 35 I J' k rsühnft 2,6^- G^esicht 3.9^o " APIS 4,7' \ i m Stm'i.vy: \ ! .'Hjot J '/o Fig.1: The global biometrics market, share of different systems cess to sensible areas of corporations and government agencies has to be restricted, but also electronic banking and electronic commerce in general need a proper identification and authorization, so that only the legitimate user may initiate transactions. If passwords and/or PIN codes are forgotten, the respective service is no longer available. For the identification of the legitimate users biometric methods are best suited, which are based on constant features of the user's human body. Examples are the human speech, some characteristics of the face, the signature, structures of the human eye (pattern of the retina and iris) and many more. According to (Fig.1, /1/) most applications use pattern of the hand and fingers (65,7%) followed by voice recognition systems (21,4%). All other systems only have a small share of the overall biometrics market, either because of a high complexity of the systems needed, or because of the somehow invasive character of the measurement (e.g. illumination of the eye needed for the evaluation of the retina patterns). Simple, reliable and cheap systems are needed for the emerging security market for applications in PCs, telecommunication systems and electronic commerce applications. 2. The fingerprint as a unique characteristic of human beings A typical fingerprint, covering an area of ca. 100 mm^, shows about 12 characteristic positions, the so called minutia (Fig. 2). These minutia can be used as unique features for the identification of people. If compared to other methods, the fingerprint recognition systems offer several advantages: Since about 150 years the criminal science has carried out exhaustive theoretical and practical investigations on the use of fingerprints An almost infinite number of variations (>>10^^) enable the reliable and unique identification of all living people and even future generations The characteristics of the fingerprint do not change over the lifetime of a human being, even after most injuries the skin recovers in exactly the same pattern. The use of fingerprint identification systems is easy and pleasant, compared e.g. to systems based on the retina patterns and needing illumination and camera systems. » Authentication: The person enters his/her ID, after-w/ards the system verifies the identity and rejects the access in the case of a mismatch. ® Identification: The system identifies the person based on the fingerprint presented and rejects all not previously stored persons. Up to now the recording and the evaluation of finger prints was a costly procedure using very sophisticated equipment. With the availability of the monolithic „Fingertip-Sensor-System" it is now possible to record fingerprints very easily and to evaluate and identify the respective persons in a very short time. The whole process takes only a few seconds. Only if the extracted features correspond to the previously stored ones the protected device, system or transaction is released for the desired operation. Fig. 2: Fingerprint record, features marl