U.S. Philips Corporation

Guido J Dormans

Robertus D Verhaar

Roger Cuppens

The invention provides a method of combining an EPROM (or EEPROM) with a standard CMOS process. After growing the gate oxide 9, a lightly doped polycrystalline or amorphous silicon layer 10, hereinafter referred to as poly I, is deposited. In this layer, the floating gate 13 of the memory cells is defined, while, outside the memory matrix, the surface remains covered with poly I. Subsequently, the source/drain implantation in the memory cells is carried out. The poly layer 10 situated outside the memory matrix is masked against this heavy implantation by the mask 11. Subsequently, a second poly layer can be provided from which the control gates of the memory cells are formed and which forms a coherent layer with the existing poly I layer outside the matrix. In a subsequent series of steps in a standard CMOS process, the n-ch MOSTs and p-ch MOSTs are provided, n-type gates 22 for the n-ch MOSTs and p-type gates 23 for the p-ch MOSTs being formed from the poly I layer.

Method of manufacturing a non-volatile memory and a CMOS transistor

The invention relates in particular, though not exclusively, to an integrated circuit with an embedded non-volatile memory with floating gate (10). According to the invention, at least two poly layers of equal or at least substantially equal thickness are used for this device. The first poly layer, poly A, is for the floating gate (10) and for the gates (22) of NMOS and PMOS in the logic portion of the circuit. The second poly layer, poly B, serves exclusively for the control electrode (21) above the floating gate. If so desired, a third poly layer may be deposited for both the control electrode and the logic gates, so that the thicknesses of these electrodes, and thus their resistances, are given desired values. Problems like overetching and bridging during saliciding are prevented in that the control electrode and the logic gates have the same thickness.

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Eindhoven, Netherlands

Guido J Dormans