TWI484491B - Optical controlled read only memory and manufacturing method thereof - Google Patents

Description

Light control read only memory and manufacturing method thereof

The present invention relates to a read-only memory, and more particularly to a light-controlled read-only memory that produces a specific program code after illumination.

Read Only Memory (ROM) is a type of semiconductor memory that is commonly used in electronic or computer systems that do not require frequent data changes, and the data does not disappear because the power is turned off. For example, the Basic Input Output System (BIOS) of a personal computer or a variety of other microcomputer systems, portable electronic products, home appliances, toys in the body (Firmware).

Currently known commercial read-only memory (ROM) can be roughly divided into: 1) programmable programmable memory (PROM), which has a determinant fuse inside, can be used The manufacturer (manufacturer) needs to use current to blow it to write the required data and programs. Once burned, it cannot be changed. 2) Erasable Programmable Read Only Memory (Erasable Programmable Read Only Memory) EPROM), which can program data by high voltage, and expose the line to ultraviolet light during erasing, the data can be emptied and can be reused. A quartz transparent window is usually reserved on the package housing for easy exposure; 3) One Time Programmable Read Only Memory (One Time Programmable Read Only Memory, OTPROM), its writing principle is the same as erasable programmable read-only memory (EPROM), but in order to save cost, it is not erased after programming and writing, so no transparent window is set; and 4). Electronically erasable In addition to Programmable Erasable Programmable Read Only Memory (EEPROM), the operation principle is similar to that of Programmable Read Only Memory (EPROM), but the erase method is done using a high electric field, so it is not required. Transparent window.

In addition, the structure and process of each read-only memory are different depending on the operation modes such as writing, erasing, and programming. For example, please refer to the read-only memory disclosed in U.S. Patent No. 5,959,877. As shown in FIG. 1, FIG. 1 is a schematic diagram showing the structure of a conventional read-only memory (ROM) formed on a substrate 1 and having a plurality of n-type dopings on the substrate 1. Miscellaneous zones 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, a plurality of insulating films 3-1, 3-2, 3-3, 3-4, 3-5 and a plurality of polysilicon films 4-1, 4-2, 4-3, 4-4, 4-5 respectively disposed on the insulating films; wherein, by the polysilicon films, The insulating film disposed under the polysilicon film and the n-type doping regions disposed on both sides of the film define a plurality of n-channel MOS transistors (hereinafter referred to as NMOS transistors) on the substrate 1 and Each of the polycrystalline germanium films is a gate of each of the NMOS transistors and electrically connected to a corresponding word line, and the n-type doped regions are the source/drain of the NMOS transistor. The read-only memory further includes a first metal wire layer (first Metal wiring layer) 5-1, 5-2, 5-3, 5-4, 5-5, 5-6 and a second metal wiring layer 6-1, 6-2, 6- 3, 6-4, 6-5, 6-6, wherein a portion of the first metal wire layer and the second metal wire layer are provided with a plurality of via plugs 10-1, 10-2, 10- 5, 10-6, and the first metal conductive layers 5-1, 5-2, 5-3, 5-4, 5-5, 5-6 and the respective n-type doped regions 2-1, 2-2 2-3, 2-4, 2-5, and 2-6 are also electrically connected by a plurality of via plugs.

The second metal layers 6-2, 6-3, 6-4, 6-5 are bit lines BL ₀ , BL ₁ , BL ₂ , BL ₃ of the read-only memory, and the same The boundary between the line and the word line is the memory cell for storing data, wherein the bit lines BL ₀ and BL ₃ are doped by the interposer 10-2, 10-5 and the underlying n-type doping. Zones 2-2, 2-5 are electrically connected. At the same time, in the production of the read-only memory, the setting of the interposer between the second metal conductive layer and the first metal conductive layer in the memory cell determines whether the information stored in the memory cells is "0" or "1", which in turn constitutes the program code of the read-only memory. Therefore, when reading the data stored in the read-only memory, the voltage from the word line will turn on the NMOS transistors via the gate of the electrical connection, and the bit line will be given a pre- Precharge potential. Since the via plugs 10-2, 10-5 are electrically connected to the second metal layers 6-2, 6-5, the first metal layers 5-2, 5-5, and the n-type doped regions 2-2, 2-5 So that the potentials of the bit lines BL ₀ and BL ₃ will be lower than the precharge bit, such as a ground potential, so that the bit lines BL ₁ , BL ₂ maintained at the precharge bits will be able to interpret the memory. The data stored by the cell is "0". Conversely, the data read by the bit lines BL ₀ and BL ₃ below the precharge bit is "1".

It can be seen that the current read-only memory is not only unique in structure, but also complicated in process. Most of the processes in the wafer process stage need to determine the code of the program stored in it, or can only be burned by a specific operation step or The body and data are rewritten to determine the program code within it, and the stored program code can only have a single fixed program code at a time and cannot be variability.

One of the main objects of the present invention is to provide a light-controlled read-only memory that can be simultaneously controlled by light or electricity and a method of fabricating the light-controlled read-only memory.

To achieve the above object, the present invention provides a light-controlled read-only memory that can be simultaneously controlled by light or electricity. The light-controlled read-only memory includes a substrate, a plurality of optical sensors are disposed on the substrate, and at least one light-shielding structure is disposed above the photosensitive elements, and the light-shielding structure selectively shields portions in a predetermined layout These photosensitive elements.

The light-controlled read-only memory system of the present invention shields a portion of the photosensitive elements by a predetermined arrangement of light-shielding structures such as semi-transmissive, opaque, etc., thereby forming a predetermined program code. Such as a foreign light source The program code system that can directly reach the photosensitive element and trigger the corresponding electronic signal is defined as "1", and the memory cell that is blocked by the light-shielding structure and cannot directly reach the photosensitive element is The program code system represented by the interpretation is defined as "0". Moreover, the light-controlled read-only memory system of the present invention has two or more kinds of program codes, and can output program codes of different functions in different illumination environments.

Referring to FIG. 2, FIG. 2 illustrates a light-controlled read-only memory 10 according to a preferred embodiment of the present invention, which includes a peripheral circuit region 12 and a memory array region 14. The peripheral circuit area 12 includes a word line decoder 16 electrically connected to the plurality of word lines of the memory array area 14, and a bit line decoder 18 electrically connected to the memory. a plurality of bit lines of the array area 14, wherein the word line decoder 16 and the bit line decoder 18 are respectively electrically connected to a corresponding voltage generator (not shown) for providing operation of the optically controlled read only memory. The potential required for body 10.

As shown in FIG. 2, the memory array region 14 is further provided with a plurality of bit lines and interleaved plurality of word lines, such as the bit lines BL ₁ , BL ₂ , BL ₃ shown in the preferred embodiment. BL ₄ , word lines WL ₁ , WL ₂ , WL ₃ , WL ₄ , WL ₅ , and a plurality of memory cells 20, 22 arrayed between the word lines and the bit lines, each character The wire system is electrically connected to a predetermined memory cell in the memory array region 14, and each of the memory cells is electrically connected to a corresponding bit line, and each of the memory cells of the present invention is provided with a photosensitive element and an active component. 23, such as a MOS transistor or an active amplifier. Wherein, some of the photosensitive elements are provided with a light-shielding structure (shown in shaded in FIG. 2, such as memory cell 20), which is used as a reference for the light of the present invention as a comparison with the memory cells 22 not provided with the light-shielding structure. The memory of the program code of the read-only memory is "0" or "1", so that the memory cells in the memory array area 14 of the light-controlled read-only memory 10 can be used to store a predetermined program code.

Please refer to FIG. 3 and FIG. 4, FIG. 3 and FIG. 4 are schematic diagrams of the memory array region 14 of the photo-controlled read-only memory 10 of FIG. 2, for simplification of description, the bit line and word are omitted in the figure. Meta-line and active components. Figure 3 is a simplified view of the top view of the memory cell layout, and Figure 4 is a cross-sectional view of the third figure taken along the line AA'. The memory cell lines of the light-controlled read-only memory 10 of the present invention may be arranged in various arrays such as a stripe arrangement, a matrix arrangement, and a triangular arrangement, and the memory cells 24, 26, 28, 30, 32 of the second row will be hereinafter. As an example to illustrate.

Please refer to Figure 3 and Figure 4 together. The memory cells 24, 26, 28, 30, 32 are disposed on a substrate 34, such as a semiconductor substrate, and each memory cell corresponds to a photosensitive element 36a, 36b, 36c, 36d, 36e, and the photosensitive elements are on the substrate. Also arranged in an array, wherein the photosensitive element 36 can be a charge coupled device (CCD) or a complementary MOS semiconductor. A group of photodiodes such as a CMOS image sensor (CIS). The memory cells 24, 26, 28, 30, 32 are further formed with a plurality of dielectric layers 38, 40, 42 of inter-metal dielectrics (IMD), etc., covering the substrate 34 and the photosensitive elements. Above 36. Moreover, the present invention can integrate a self-aligned metal salicide process, a multi-level interconnection process, a color filter process, a black matrix process, etc., in each memory cell 24, 26 The desired light-shielding structure is formed in 28, 30, and 32.

Comparing the structures of the memory cells 24, 26, 28, 30, 32 in FIGS. 3 and 4, wherein the memory cell 24 includes only one photosensitive element 36a, and no light-shielding structure is disposed above the photosensitive element 36a, from the memory. The light source outside the cell 24 can pass through the dielectric layer 38, 40, 42 directly to the photosensitive element 36a, and trigger a corresponding electronic signal, which can be regarded as the presence or recording of a bit of metadata, such as "1" in the program code. In contrast, the photosensitive elements 36b, 36c, 36d, and 36e of the memory cells 26, 28, 30, and 32 are respectively provided with corresponding light shielding structures, for example, the metal halide 44 in the memory cell 26 and the memory cell 28 are disposed in the photosensitive layer. A first patterned metal layer 46 and a second patterned metal layer 48 over element 36c. Therefore, when the external light source is directed to the memory cells 26 and 28, it can be blocked by the opaque layer such as the metal halide 44, the first patterned metal layer 46, and the second patterned metal layer 48, and cannot directly reach the photosensitive layer. Elements 36b, 36c, so both can be considered to exist or have another bit of data, such as "0" in the program code.

As for the memory cell 30, a first color filter layer 50 is disposed on the dielectric layer 42 as a semi-transmissive layer, and the memory cell 32 is further provided with a second color on the first color filter layer 50. The filter layer 52 constitutes an opaque layer. Therefore, when the external light source is white light or red light, the light can be selectively passed through the red first color filter layer 50 and directly reach the photosensitive element 36d of the memory cell 30, and can be regarded as having or recorded a bit. Metadata, such as "1" in the program code; but for the memory cell 32, due to its color filter layer having different filter ranges, that is, the second color of the green color on the first color filter layer 50 The color filter layer 52 blocks the light source other than the green light from entering the first color filter layer 50, and the first color filter layer 50 blocks the light source other than the red light from entering the dielectric layer 42, so that the photosensitive element is not caused. The electronic signal of 36e due to the incidence of photons can be regarded as the presence or recording of another bit of data, such as "0" in the program code.

Therefore, by selectively shielding a portion of the photosensitive elements in a predetermined arrangement by the light-shielding structures such as semi-transparent and opaque, the present invention can write a predetermined program code. For example, the external light source can directly reach the photosensitive element to trigger the corresponding electronic signal, so that the program code of the memory cell is defined as "1", and the memory cell that is blocked by the light shielding structure and cannot directly reach the photosensitive element is It will be interpreted as the program code system it represents as "0". On the contrary, the present invention can also directly connect the external light source to the photosensitive element to trigger the corresponding electronic signal, so that the coded code of the memory cell is defined as "0", and can not be directly blocked by the light shielding structure. The memory cell that reaches the photosensitive element is interpreted as the code system it represents as "1", depending on the operation. From this, the program code stored in the optical control read-only memory can be determined, and the code of the program is controlled by "electricity" and "light".

Please refer to FIG. 5, which illustrates a light-controlled read-only memory 10 of other preferred embodiments of the present invention. Similarly, in order to simplify the description, bit lines, word lines, and active elements are omitted in the drawings, and the same elements are denoted by the same reference numerals. The memory cell 24 only includes a photosensitive element (not shown), and no light-shielding structure is disposed above the photosensitive element, so that the external light source can directly reach the photosensitive element through the dielectric layer (not shown) and generate corresponding electronic signals. It can be regarded as the existence or recording of a meta-data, such as "1" in the program code. The photosensitive element of the memory cell 26 is provided with an opaque light-shielding structure, such as a metal telluride, a metal plug, a patterned metal layer, a black matrix or two or more color filters of different filter ranges, so When the external light source is directed to the memory cell 26, it is blocked by the opaque layer and cannot directly reach the photosensitive element in the memory cell 26, so it can be regarded as having or recorded another bit data, such as in the program code. "0". The photosensitive elements on the photosensitive elements of the memory cells 54, 56 are respectively provided with a half-transparent light-shielding structure, a red color filter and a green color filter, so that an external light source at a specific wavelength can cause a corresponding light source. Electronic signal. For example, when the memory cell 54 is illuminated by white light or red light, or when the memory cell 56 is illuminated by white light or green light, it may be considered that one meta data exists, such as "1" in the program code; For other wavelengths of the external light source, the photosensitive element in the memory cell 54 or the memory cell 56 cannot be sensitive, so it can be regarded as having or recording another bit data, such as "0" in the program code.

Therefore, the light-controlled read-only memory 10 of the preferred embodiment selectively combines and outputs different program codes in different color illumination environments, for example, when using white light, the memory cell 24, the memory cell 54 and the memory cell The photosensitive element in 56 can be photosensitive, and the photosensitive element in the memory cell 26 cannot be photosensitive, which constitutes a first program code; when using red light, the memory cell 24 and the photosensitive element in the memory cell 54 can be Photosensitive, while the memory cells 26 and the photosensitive elements in the memory cells 56 are not sensitive, they combine to form a second code; when using green light, both the memory cells 24 and the photosensitive elements in the memory cells 56 can be photosensitive. However, the memory cells 26 and the photosensitive elements in the memory cells 54 are not sensitive to light, and the combination constitutes a third specific program code. Moreover, the first program code, the second program code, and the third program code respectively correspond to program codes of different functions.

Please refer to FIG. 6. FIG. 6 illustrates a light-controlled read-only memory 10 according to still another preferred embodiment of the present invention. Similarly, in order to simplify the description, bit lines, word lines, and active elements are omitted in the drawings, and the same elements are denoted by the same reference numerals. In the preferred embodiment, the photosensitive memory cell of the present invention can be regarded as a selected switching element for controlling different program codes. As shown in FIG. 6, the light-controlled read-only memory 10 includes a main program code CODE A and a plurality of sub-program codes CODE. B, CODE C, CODE D, CODE E, and a plurality of memory cells 24, 26, 54, 58 are coupled between the primary and secondary program codes, respectively. The memory cell 24 only includes a photosensitive element (not shown), and no light-shielding structure is disposed above the photosensitive element, so that the external light source can directly reach the photosensitive element through the dielectric layer (not shown) and generate corresponding electronic signals. It can be regarded as selecting the subcode encoding CODE B. The photosensitive element of the memory cell 26 is provided with an opaque light-shielding structure, such as a metal telluride, a metal plug, a patterned metal layer, a black matrix or two or more color filters of different colors, so that when When the light source is directed to the memory cell 26, it is blocked by the opaque layer and cannot directly reach the photosensitive element in the memory cell 26. Therefore, it can be regarded as not selecting the subcode CODE C. The photosensitive elements of the memory cells 54, 58 are respectively provided with a light-blocking structure such as a red color filter and a blue color filter, so that the memory cell 54 is exposed to white light or red light, or the memory cell 58 is white light. Or when the blue light is irradiated, it can be regarded as selecting the subprogram code CODE D and CODE E respectively; on the contrary, for the external light source of other wavelengths, the photosensitive element in the memory cell 54 or the memory cell 58 cannot be sensitive, so it can be regarded as not selecting the subprogram code. D, E. Therefore, in different lighting environments, different main program codes and sub-program codes can be combined to output different program codes. In addition, the present invention can further encode some or all of the memory cells of the main program code or the sub-program code, and adopt the structural design of the memory cells having the light-transmitting and opaque light-shielding structures of the foregoing two embodiments, so that the main program code Or a plurality of sub-program codes themselves, which can display different program codes under different illumination environments, and then select the memory cells 24, 26, 54, 58 of the embodiment to select Different subprograms encode and combine the main program code output to achieve multi-segment light control program coding.

Based on the above description, the light-controlled read-only memory of the present invention can be effectively integrated into the semiconductor process of the photoreceptor diode of the current complementary CMOS image sensor (CIS), that is, the fab can be mass-produced first. The semiconductor wafer of the photodiode array is further modified by a semi-transmissive layer such as a metal halide, a via plug, a metal layer, a black matrix, or the like, or a color filter. The reticle layout design can constitute the light-controlled read-only memory of the present invention corresponding to a predetermined program code, or can only prepare a general complementary CMOS image sensor (CIS), which is cost-effective and effective. Reduce the process of read-only memory. Moreover, the light-controlled read-only memory of the present invention can have more than two kinds of program codes, and output different function code codes in different illumination environments, and completely change the conventional read-only memory to store only a single fixed one at a time. Program-encoded and non-changing features.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

1, 34‧‧‧ base

2-1, 2-2, 2-3, 2-4, 2-5, 2-6‧‧‧n doped regions

3-1, 3-2, 3-3, 3-4, 3-5‧‧‧ insulating film

4-1, 4-2, 4-3, 4-4, 4-5‧‧‧ polysilicon film

5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 46‧‧‧ first metal wire layer

6-1, 6-2, 6-3, 6-4, 6-5, 6-6, 48‧‧‧ second metal wire layer

10-1, 10-2, 10-5, 10-6‧‧‧ interlayer plug

BL ₀ , BL ₁ , BL ₂ , BL ₃ , BL ₄ ‧‧‧ bit lines

WL ₁ , WL ₂ , WL ₃ , WL ₄ , WL ₅ ‧‧ ‧ character lines

10‧‧‧Light-controlled read-only memory

12‧‧‧ peripheral circuit area

14‧‧‧Memory array area

16‧‧‧ character line decoder

18‧‧‧ bit line decoder

23‧‧‧Active components

20, 22, 24, 26, 28, 30, 32, 54, 56, 58‧‧‧ memory cells

36, 36a, 36b, 36c, 36d, 36e‧‧‧ photosensitive elements

38, 40, 42‧‧‧ dielectric layer

44‧‧‧Metal Telluride

50‧‧‧First color filter layer

52‧‧‧Second color filter layer

CODE A‧‧‧ main program code

CODE B, CODE C, CODE D, CODE E‧‧‧ subprogram code

Figure 1 is a schematic diagram showing the structure of a conventional read only memory (ROM).

2 is a schematic view of a light-controlled read-only memory according to a preferred embodiment of the present invention Figure.

Figure 3 is a top view of the memory array area of the light-controlled read-only memory.

Fig. 4 is a schematic cross-sectional view taken along line AA' of Fig. 3.

Figure 5 is a schematic diagram of a light-controlled read-only memory of other preferred embodiments of the present invention.

Figure 6 is a schematic diagram of a light-controlled read-only memory according to still another preferred embodiment of the present invention.

10‧‧‧Light-controlled read-only memory

12‧‧‧ peripheral circuit area

14‧‧‧Memory array area

16‧‧‧ character line decoder

18‧‧‧ bit line decoder

23‧‧‧Active components

20, 22‧‧‧ memory cells

36, 36a, 36b, 36c, 36d, 36e‧‧‧ photosensitive elements

BL ₁ , BL ₂ , BL ₃ , BL ₄ ‧‧‧ bit lines

WL ₁ , WL ₂ , WL ₃ , WL ₄ , WL ₅ ‧‧ ‧ character lines

Claims (20)

An optically controlled read-only memory (optical controlled ROM) comprising: a substrate; a plurality of memory cells each having an optical sensor are disposed on the substrate; and at least one light shielding structure is disposed on the portion The light-receiving elements are disposed directly above, and the light-shielding structure is configured to shield the light source from entering the photosensitive element, and selectively masking the photosensitive elements in a predetermined layout, wherein the memory cell includes a predetermined program code, and the predetermined The state of the program code is controlled by whether or not the photosensitive elements are shielded. The photo-controlled read-only memory according to claim 1, wherein each of the photosensitive elements is selected from a photodiode such as a charge coupled device (CCD) or a complementary MOS image sensor (CIS). Group. The light-controlled read-only memory of claim 1, wherein the predetermined layout corresponds to a program code. The photo-controlled read-only memory of claim 3, wherein the photosensitive elements that are shielded by the light-shielding structure and the photosensitive elements that are not shielded by the light-shielding structure constitute the program code. The light-controlled read-only memory according to claim 1, wherein the light-shielding structure is an opaque layer, and the light-shielding structure is selected from the group consisting of a metal germanium layer, a metal plug, a metal layer or a stack of at least two different filters. A group of color filter layers of the light range. The light-controlled read-only memory of claim 1, wherein the light-shielding structure is a half-transmissive layer. The photo-controlled read-only memory of claim 6, wherein the light-shielding structure comprises a color filter layer. The light-controlled read-only memory of claim 1, wherein the light-controlled read-only memory further comprises a plurality of word lines, a plurality of bit lines, and a plurality of active elements, and each of the active elements is electrically connected Each of the photosensitive elements is coupled to a corresponding set of word lines and the bit lines. The photo-controlled read-only memory of claim 8, wherein the active component comprises an MOS transistor or an active amplifier. A method for fabricating a light-controlled read-only memory, comprising: providing a substrate; forming a plurality of photosensitive elements on the substrate; and selectively selecting a portion of the surface directly above the photosensitive elements in a predetermined layout Forming a first light-shielding structure, wherein the first light-shielding structure is used to shield the light source from entering the photosensitive element, wherein the state of the light-controlled read-only memory is controlled by whether the photosensitive elements are shielded or not. The method of claim 10, wherein the predetermined layout corresponds to a program code. The method of claim 10, wherein the first light shielding structure comprises a metal halide layer. The method of claim 10, further comprising forming a dielectric layer on the substrate and covering the photosensitive elements and the first light shielding structures. The method of claim 13, further comprising forming the at least one second light-shielding structure on the dielectric layer and selectively shielding the photosensitive elements on the surface from which the first light-shielding structure is not formed. The method of fabricating the method of claim 14, wherein the method of forming the second light-shielding structure comprises a multi-level interconnection process or a color filter process. The method of claim 14, wherein the second light shielding structure comprises a color filter layer stacking at least two different filter ranges. A method for fabricating a light-controlled read-only memory, comprising: providing a substrate; forming a plurality of photosensitive elements on the substrate; forming a dielectric layer on the substrate and covering the photosensitive elements; and surface of the dielectric layer Forming at least one light-shielding structure, and the light-shielding structure selectively shields the photosensitive elements directly under the portion in a predetermined layout to shield the light source from entering the photosensitive element, wherein the state of the light-controlled read-only memory is The photosensitive element is controlled by being shielded or not. The method of claim 17, wherein the predetermined layout corresponds to a program code. The method of fabricating the method of claim 17, wherein the method of forming the light-shielding structure comprises a multi-level interconnection process or a color filter process. The method of claim 17, wherein the light shielding structure comprises a color filter layer stacking at least two different filter ranges.