The foregoing and other objects, features and advantages of the invention will be apparent from the more particular description of preferred aspects of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the drawings, the thickness of layers and regions are exaggerated for clarity.
Merits and novel characteristics of the invention will become more apparent from the following detailed description and exemplary embodiments taken in conjunction with the accompanying drawings. However the present invention is not limited to the disclosed embodiments, but may be implemented in various manners. The embodiments are provided to complete the description of the present invention and to allow those having ordinary skill in the art to understand the scope of the present invention. The present invention is defined only by the claims. The same reference numbers will be used throughout the drawings to refer to the same or like parts.
The present invention is described in detail in connection with preferred embodiments with reference to the accompanying drawings.
Hereinafter, the program operation refers to an operation of charging a floating gate with electric charges, and the erase operation refers to an operation of discharging electric charges from a floating gate. However, it will be apparent to those skilled in the art that, depending on the operation of an integrated circuit device, the discharging of a floating gate with electric charges may be a program operation and the charging of electric charges from a floating gate can be an erase operation.
Global word lines GWL0 to GWLn are selectively connected to the word lines WL0 to WLn, which are arranged in every cell block, through byte select transistors T3. The gates of a plurality of byte select transistors T3 located along the same column are interconnected by one of byte select lines BSL0 to BSL3.
However, with reference to
Referring first to
The term “substantially rectangular” basically refers to a rectangle, but includes a polygon some or all of the four corners of which are chamfered for the efficiency of layout. The chamfering may be performed not only in a straight-line form, but also in a rounded form.
Furthermore, as shown in
A plurality of first active regions ACT1, extending in the row direction ROW, and a plurality of second active regions ACT2, extending in the column direction COLUMN to cross the plurality of first active regions ACT1, are defined by the substantially rectangular field regions 110.
A tunneling-prevention dielectric layer pattern 130 may be arranged parallel to the row direction ROW on the semiconductor substrate in which the plurality of substantially rectangular field regions 110 is formed. A tunneling dielectric layer (not shown) is formed on the entire surface of the semiconductor substrate in which the tunneling-prevention dielectric layer pattern 130 is formed.
The word lines WL0, WL1, WL2, and WL3 and the select lines SL0, SL1, SL2, and SL3, extending parallel to the row direction ROW, are arranged on the semiconductor substrate in which the tunneling dielectric layer is formed.
In more detail, two select lines SL0 and SL1, or SL2 and SL3 cross the plurality of substantially rectangular field regions 110 arranged in the row direction ROW of the matrix. Two word lines WL0 and WL1, or WL2 and WL3 are interposed between the two select lines SL0 and SL1, or SL2 and SL3, and cross the plurality of substantially rectangular field regions 110 arranged in the row direction ROW of the matrix. More particularly, the word lines WL0, WL1, WL2, and WL3 may partially overlap the tunneling-prevention dielectric layer pattern 130.
Furthermore, a common source region 122 is formed within the first active region ACT1 between two select lines SL1 and SL2. A bit line junction region 126 is formed within the second active region ACT2 between two word lines WL0 and WL1, or WL2 and WL3. A floating junction region 124 is formed within the second active region ACT2 between each of the select lines SL0, SL1, SL2, and SL3 and each of the word lines WL0, WL1, WL2, and WL3.
Referring to
The second conduction-type (for example, the N-type) first well 102 is formed within the first conduction-type (for example, the P-type) semiconductor substrate 101. The first conduction-type (for example, the P-type) second well 104 is formed within the first well 102.
The semiconductor substrate 101 may be a silicon substrate, a Silicon On Insulator (SOI) substrate, a GaAs substrate, a SiGe substrate, a ceramic substrate, or a quartz substrate. For example, the semiconductor substrate 101 may be a single crystalline silicon substrate doped with a P-type impurity. The concentration of the P-type impurity may be in the range of about 1014 to 1015 atoms/cm3. Furthermore, the concentration of the N-type impurity of the first well 102 may be in the range of about 1015 to 1016 atoms/cm3, and the concentration of the P-type impurity of the second well 104 may be in the range of about 1016 to 1017 atoms/cm3.
A field region is formed within the semiconductor substrate 101, thus defining the active region. The field region may be generally made of Field Oxide (FOX) using a Shallow Trench Isolation (STI) or Local Oxidation of Silicon (LOCOS) method.
The memory transistor T1 and the select transistor T2 are formed within the second well 104. In an embodiment, the memory transistor T1 and the select transistor T2 respectively include a memory gate 140 and a select gate 150, which are formed on a tunneling dielectric layer 135. More particularly, in an embodiment, the non-volatile memory integrated circuit device includes the tunneling-prevention dielectric layer pattern 130, which is interposed between the semiconductor substrate 101 and the tunneling dielectric layer 135 and overlaps at least part of the memory gate 140. Although, in
The tunneling dielectric layer 135 may be a single film made of SiO2, SiON, La2O3, ZrO2 or Al2O3, or a stack or combination film made of SiO2, SiON, La2O3, ZrO2 and Al2O3. The thickness of the tunneling dielectric layer 135 may be about 60 to 100 {acute over (Å)}, for example, 65 to 75 {acute over (Å)}, but is not limited thereto. Furthermore, the tunneling-prevention dielectric layer pattern 130 may be a single film made of SiO2, SiON, La2O3, ZrO2 or Al2O3, or a stack or mixed film made of SiO2, SiON, La2O3, ZrO2 and/or Al2O3. The tunneling-prevention dielectric layer pattern 130 may have a thickness greater than that of the tunneling dielectric layer 135. The thickness of the tunneling-prevention dielectric layer pattern 130 may be about 100 to 300 {acute over (Å)}, but is not limited thereto.
In a conventional non-volatile memory cell, electric charges are programmed or erased through the front surface of the tunneling dielectric layer below the memory gate using FN tunneling. That is, the tunneling region is the front surface of the tunneling dielectric layer of the memory gate. In the present invention, the tunneling-prevention dielectric layer pattern 130 is formed in order to reduce the area of the tunneling region. The region in which the tunneling-prevention dielectric layer pattern 130 and the tunneling dielectric layer 135 overlap each other is much thicker than the region in which only the tunneling dielectric layer 135 is formed. Therefore, if a voltage is applied to the memory gate 140, the second well 104, and the bit line junction region 126 to the extent that electric charges can perform FN tunneling only across the tunneling dielectric layer 135, the electric charges cannot perform FN tunneling across the region in which the tunneling-prevention dielectric layer pattern 130 and the tunneling dielectric layer 135 overlap each other. That is, the tunneling region is confined to the region in which only the tunneling dielectric layer 135 is formed below the memory gate 140.
If the tunneling region is reduced as described above, the coupling ratio is increased at the time of the program/erase operations. Accordingly, the program/erase efficiency can be improved. This will be described in detail below with reference to
The floating gate 142 is formed on the tunneling dielectric layer 135, and may be formed of a polycrystalline silicon film doped with an impurity. The thickness of the floating gate 142 may be about 1000 to 3000 {acute over (Å)}, but is not limited thereto. The floating gate 142 serves to store electrical charges that determine the logic state of the non-volatile memory integrated circuit device.
The inter-gate dielectric layer 144 is formed on the floating gate 142, and may be a single film formed of an oxide film or a nitride film, or a stack or mixed film formed of an oxide film and a nitride film. For example, a stack film formed of an oxide film, a nitride film and an oxide film (a so-called “ONO film”) may be generally used as the inter-gate dielectric layer 144. The lower oxide film may have a thickness of 100 {acute over (Å)}, the nitride film may have a thickness of 100 {acute over (Å)}, and the upper oxide film may have a thickness of 40 {acute over (Å)}.
The control gate 146 is formed on the inter-gate dielectric layer 144. Although not shown in the drawings, a capping film may be further formed on the top of the control gate 146.
The plurality of conductive films 152 and 156 of the select gate 150 may be formed to have the same thicknesses and use the same materials as those of the floating gate 142 and the control gate 146, respectively.
The floating junction region 124 is located within the semiconductor substrate 101 between the memory gate 140 and the select gate 150. The bit line junction region 126 is located opposite the floating junction region 124 with respect to the memory gate 140. The common source region 122 is located opposite the floating junction region 124 with respect to the select gate 150. Although, in the drawings, the bit line junction region 126 and the common source region 122 are illustrated as having a Lightly Doped Drain (LDD) structure, in which a low-concentration impurity is shallowly doped and a high-concentration impurity is deeply doped, and the floating junction region 124 is shallowly doped only with a low-concentration impurity, the present invention is not limited thereto. For example, the floating junction region 124 may also have an LDD structure, and the bit line junction region 126 and the common source region 122 may be shallowly doped only with a low-concentration impurity.
The plurality of conductive films 152 and 156 of the select gate 150 may be electrically connected to each other. The conductive films 152 and 156 may be electrically connected to each other using a butting contact, as shown in
Hereinafter, the operation of the above-mentioned non-volatile memory integrated circuit device will be described with reference to
Table 1 shows a list of operating voltages during the respective operations of the non-volatile memory integrated circuit device. It is to be understood that Table 1 illustrates only exemplary operating voltages, and that the present invention does not exclude other operating voltages.
Referring to
Referring to
Furthermore, the non-selected non-volatile memory cell 100DD that shares the same bit line with the selected non-volatile memory cell 100 may be unintentionally programmed by a drain disturbance phenomenon. To prevent such unintentional programming, the word line WL1 coupled to the non-selected non-volatile memory cell 100DD is supplied with, for example, 0V.
Referring to
Since, in an embodiment of the present invention, the tunneling-prevention dielectric layer pattern 130 partially overlaps the memory gate 140, the tunneling region is confined only to a region in the tunneling dielectric layer 135 below the memory gate 140, compared to the prior art. If the tunneling region is reduced as described above, the coupling ratio can be increased at the time of the program/erase operations, and program/erase efficiency can be improved accordingly.
This will be described in detail with reference to
where KP1 is the coupling ratio during the conventional program operation, KE1 is the coupling ratio during the conventional erase operation, CTUN1 is the capacitance of the tunneling dielectric layer 35 below the memory gate 40, CONO is the capacitance of an inter-gate dielectric layer 44, CTOT is the sum of all capacitances, KP2 is the coupling ratio during the program operation of the present invention, KE2 is the coupling ratio during the erase operation of the present invention, CTUN2 is the capacitance of the tunneling region (that is, the capacitance of the region in which only the tunneling dielectric layer 135 is formed below the memory gate 140), CTP is the capacitance of the tunneling-preventing region (that is, the capacitance of the region in which the tunneling dielectric layer 135 and the tunneling-prevention dielectric layer pattern 130 overlap each other below the memory gate 140), CONO is the capacitance of the inter-gate dielectric layer 144, and CTOT is the sum of all capacitances.
Furthermore, if, for ease of description, it is assumed that in the right view of
That is, when Equation 3 is compared with Equation 1, CTUN1 is reduced to CTUN2 and CTP is added in the denominator of Equation 3. There is the relationship CTUN1=2CTUN2>CTUN2+CTP, therefore the coupling ratio KP2 during the program operation of the present invention is higher than the coupling ratio KP1 during the conventional program operation.
Furthermore, when Equation 4 is compared with Equation 2, CTUN1 is reduced to CTUN2 in the numerator of Equation 4. Accordingly, the coupling ratio KE2 during the erase operation of the present invention is higher than the coupling ratio KE1 during the conventional erase operation.
That is, since both the coupling ratio KP2 during the program operation and the coupling ratio KE2 during the erasing operation are increased, program/erase efficiency are increased.
Reference numerals of
Referring to
In this case, the size of the tunneling-prevention dielectric layer pattern 130a increases to more than that of
The non-volatile memory integrated circuit device of
Referring to
In more detail, the tunneling dielectric layer below the memory gate 140 includes a floating junction region (124)-side tunneling dielectric layer and a bit line junction region (126)-side tunneling dielectric layer 135 having different thicknesses. Furthermore, either the floating junction region (124)-side tunneling dielectric layer or the bit line junction region (126)-side tunneling dielectric layer is thicker than the tunneling dielectric layer below the select gate 150. Although, in
It will be apparent to those skilled in the art that the modified embodiments of
Referring to
A P-type second well 104 is formed within the first well 102. The second well 104 may be formed using diffusion or ion implantation so that a P-type impurity has a concentration of about 1017 to 1018 atoms/cm3.
Thereafter, a plurality of substantially rectangular field regions 110 is formed within the semiconductor substrate 101 in a matrix form, thus defining active regions. The substantially rectangular field regions 110 are arranged such that the short sides and long sides thereof are aligned parallel to the row and column directions of a matrix, respectively.
Referring to
Referring to
A first conductive film 142a used to form a floating gate and a dielectric layer 144a used to form an inter-gate dielectric layer are sequentially formed on the tunneling dielectric layer 130. The first conductive film may be formed to have a thickness of 1000 to 3000 {acute over (Å)} using a polycrystalline silicon film doped with an impurity through CVD.
The dielectric layer may be formed using a single film formed of an oxide film or a nitride film, or a stack or mixed film formed of an oxide film and a nitride film. For example, the dielectric layer may be formed using a stack film formed of an oxide film, a nitride film, and an oxide film (a so-called “ONO film”). The stack film formed of an oxide film, a nitride film and an oxide film may be formed to have thicknesses of 100 {acute over (Å)}, 100 {acute over (Å)}, and 40 {acute over (Å)}, respectively, through CVD or ALD.
A dielectric layer pattern 144a and a first conductive film pattern 142a are formed by sequentially performing secondary patterning P2 on the dielectric layer and the first conductive film.
Referring to
A memory gate 140, which is composed of the control gate 146, the inter-gate dielectric layer 144 and the floating gate 142, and the select gate 150, which is spaced apart from the memory gate 140 by a predetermined distance, are formed by sequentially performing third patterning P3 on the second conductive film, the dielectric layer pattern 144a of
Referring back to
Thereafter, the spacers 160 are formed on both sidewalls of the memory gate 140 and the select gate 150. In an embodiment of the present invention, the gap between the memory gate 140 and the select gate 150 is not sufficiently wide, therefore the spacer 160 formed on one side of the memory gate 140 and the spacer 160 formed on one side of the select gate 150 opposite the memory gate 140 can be connected to each other without being completely separated from each other.
Thereafter, the bit line junction region 126, the floating junction region 124, and the common source region 122 are formed by implanting an N-type high-concentration impurity at a high energy state using the memory gate 140 and the select gate 150 with the spacers 160 formed thereon as masks.
If the spacer 160 formed on one sidewall of the memory gate 140 and the spacer 160 formed on one sidewall of the select gate 150 opposite the memory gate 140 are interconnected as described above, an N-type high-concentration impurity region may not be formed in the floating junction region 124. In contrast, the bit line junction region 126 and the common source region 122 may be of an LDD type, in which a low-concentration impurity is doped shallowly and a high-concentration impurity is doped deeply. Therefore, the floating junction region 124 may be formed thin compared with the bit line junction region 126 and the common source region 122.
Thereafter, by performing the step of forming wiring so that electrical signals can be input and output to and from the memory cell, the step of forming a passivation layer on the substrate, and the step of packaging the substrate according to processes that are well known to those skilled in the semiconductor field, the non-volatile memory integrated circuit device is completed.
Referring to
The tunneling dielectric layer 135a having the above-described configuration may be formed by forming a dielectric layer to have a thickness of about 160 to 380 {acute over (Å)}, forming a photoresist pattern 190 on the dielectric layer, and time-etching a dielectric layer using the photoresist pattern 190 as a mask According to the non-volatile memory integrated circuit device and method of fabricating the device, the coupling ratios during program and erase operations can be increased, thereby improving program/erase efficiency.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Number | Date | Country | Kind |
---|---|---|---|
10-2006-0042571 | May 2006 | KR | national |