W H I T E P A P E R. Data Retention Performance of μm F-RAM Memory. Introduction. F-RAM Retention Lifetime

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1 W H I T E P P E R Shan Sun Sco Emley Cypress Semiconducor Corp. Daa Reenion Performance of 0.13-μm F-RM Memory bsrac F-RM (Ferroelecric Random ccess Memory) is a nonvolaile memory ha uses a ferroelecric capacior for soring daa. I offers higher wrie speeds over Flash/EEPROM. This whie paper provides a brief overview of daa reenion performance of F-RM memory. Inroducion This documen confirms he daa reenion specificaions of EC- Q100 Grade 3, Grade 2, and Grade 1 (0.13 μm) F-RM Memory Producs. If operaed wihin he produc specificaion and wih 2T2C cell srucure, F-RM has heoreically unlimied Same Sae (SS) daa reenion and limied Opposie Sae (OS) daa reenion. The predicion of OS reenion ime of 0.13-μm F-RM Memory Producs is based on he reliabiliy es resuls afer exended bakes and he acivaion energy (Ea) of 1.4 ev. This paper provides a mehod o calculae he OS daa reenion life ime for cusomized emperaure profiles. F-RM Reenion Lifeime primary measure of reliabiliy of F-RM is he reenion lifeime of a capacior cell ha has been previously sored in a polarizaion sae for an exended ime and hen wrien o he opposie polarizaion sae. This ype of reenion is known as Opposie Sae (OS) reenion. The effec of imprin makes he previously sored sae, or so-called Same Sae (SS), more sable wih longer sore ime. Therefore, F-RM has an unlimied SS reenion life wihin he specified emperaure range. This whie paper focuses on OS reenion performance. OS Reenion is ofen specified as an amoun of ime a a given consan emperaure. Thus he OS reenion (ime) specificaion of EC-Q100 Grade 3, 2, and 1 F-RM producs for consan emperaure profiles are given along wih a cumulaive scenario of muliple emperaure profiles over he life of he produc. EC-Q100 Grade 3 (uomoive-) F-RM OS Reenion Based on acceleraed and exended sress experimenal resuls and Ea of 1.4 ev, 10 years of OS reenion a 85 ºC is guaraneed. The OS reenion ime a various emperaures are calculaed as shown in Figure 1. The OS reenion increases exponenially as emperaure decreases. For example, i is 38 years a 75 ºC and >100 years a 65 ºC. Below 65 ºC, he OS reenion is virually unlimied. Daa Reenion Performance of Rev. * July μm F-RM Memory

2 2 Cypress Semiconducor Corp. Figure 1. OS Reenion Time of uomoive Grade 3 F-RM a Various Temperaures EC-Q100 Grade 2 F-RM OS Reenion Based on acceleraed and exended sress experimenal resuls and Ea of 1.4 ev, 5 years or 43.8 khours of OS reenion a 105 ºC is guaraneed. The OS reenion ime a various emperaures are calculaed as shown in Figure 2. This specificaion can be convered o more common emperaures. For example, i is equivalen o 43 khours a 105 ºC plus 64 years a 55 ºC. The life ime predicion for specific applicaion emperaure profiles will be discussed in a laer secion. Figure 2. OS Reenion Time of uomoive Grade 2 F-RM a Various Temperaures Daa Reenion Performance of Rev. * July μm F-RM Memory

3 3 Cypress Semiconducor Corp. EC-Q100 Grade 1 (uomoive-e) F-RM OS Reenion The acceleraed and exended sress experimenal resuls sugges ha he OS reenion ime of Grade 1 F-RM producs is >11,163 hours a 125 ºC. This resul suppors he specificaion of 11,000 hours a 125 ºC. The specified OS reenion ime a various emperaures wihin he specified emperaure range (-40 ºC o 125 ºC) are calculaed as shown in Figure 3. The specificaion can be convered o oher emperaure profiles. The life ime predicaion of specific applicaion emperaure profiles is illusraed in he nex secion. Figure 3. OS Reenion Time of uomoive Grade 1 F-RM a Various Temperaures OS Reenion Life Predicaion for Cusomized Temperaure Profiles Mos of he previous secions focused on he OS daa reenion specificaion of EC-Q100 Grade 1, Grade 2, or Grade 3 F-RM a a fixed emperaure. However, i is rare for an applicaion o acually operae under a seady emperaure for he enire usage life ime of he applicaion. Insead, an applicaion is ofen expeced o operae in muliple emperaure environmens hroughou he applicaion s usage life ime. ccordingly, he reenion specificaion for F-RM in applicaions ofen needs o be calculaed cumulaively. For example: ssuming an applicaion uses Grade 1 F-RM a differen emperaure profiles over he following usage life ime: Temperaure 1 = 125 ºC for 10% of ime (1) Temperaure 2 = 105 ºC for 15% of ime (2) Temperaure 3 = 85 ºC for 25% of ime (3) Temperaure 4 = 55 ºC for 50% of ime (4) Following he rrhenius equaion, he acceleraion facor beween T and Tmax is: Where k is he Bolzmann consan ev/k, Tmax is he highes emperaure specified for he F-RM produc, and T is any emperaure wihin he F-RM produc specificaion. ll Daa Reenion Performance of Rev. * July μm F-RM Memory

4 4 Cypress Semiconducor Corp. emperaures are in Kelvin in he above equaion. The acceleraion facors are calculaed and lised in Table 1. Temperaure Time Facor cceleraion Facor wr Tmax Profile Facor Profile Life Time (T) () () (P) L(P) T1 = 125 ºC 1 = = 1 T2 = 105 ºC 2 = = 8.67 T3 = 85 ºC 3 = = T4 = 55 ºC 4 = = The Profile facor P is deermined by: = 8.33 Table 1. cceleraion Facors = years The OS reenion life ime predicion of a emperaure profile, L(P), is given by: Where L(Tmax) is he specified OS reenion ime 11,000 hours a 125 ºC. The calculaion process and resuls are lised in Table 1. I can be observed ha he life ime of a profile is dominaed by he highes usage emperaure and is ime facor. Noe ha in he calculaion, T is equal o or lower han Tmax. I is mahemaically correc o use in equaions when T > Tmax, and T < Tmin; however Cypress does no guaranee he pars working properly when T is ou of he emperaure specificaions. Summary Table 2 summarizes he Tmax, he OS reenion life ime specificaion a Tmax i.e., L(Tmax), and OS reenion life ime calculaion of a general emperaure profile. F-RM Produc Tmax OS Reenion a Tmax Grade ºC 11 khours Grade ºC 5 years Grade 3 85 ºC 10 years OS Reenion Life Time of Temperaure Profile Deermined by Cusomers, Table 2. Summary of OS Reenion Daa Reenion Performance of Rev. * July μm F-RM Memory

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