TWI232552B - Data write-in method of mask read only memory - Google Patents

Abstract

A kind of mask ROM (read only memory) that uses different dose of ion implantation to perform data write-in process is disclosed in the present invention. On the semiconductor substrate that has plural gate structures, the mask designed according to the information provided by the customer (user) is used to conduct different dose of ion implantation so as to generate different voltage output values. Different voltage output values are then defined as (00), (01), (10), and (11) for the bit output. Thus, the invention is capable of reducing the memory area required for completing a specific data record so as to decrease the bit cost.

Description

1232552

[Technical field to which the invention belongs] The present invention relates to a data writer for a photomask type read-only memory, and in particular, to a method using four different ion implantation volumes: the entry method ♦ 1〒 is a bit ) Mask read-only memory for data writing. [Previous technology] Mask Read Only Menu (YMR0M) is a type of non-volatile memory IC, and it is a plan that uses a mask in the SI wafer purple fabrication process Program data content (Program) ^ = memory device for permanent storage. Because it is not good to write the action, the overall circuit configuration is relatively simple, and the basic memory cell is also very simple. It consists of only one M 0 S-type transistor (μ 〇s Trans is tor), and can rewrite memory information at any time. Compared with Random Access Memory (RAM), it is only a quarter of its size—so for a chip of the same size, the MR0M memory capacity is about four times that of RAM ', so it is very economical and is widely used. It is used in various electronic products such as information, communication, and consumer electronics. The data writing process is made by using a photomask designed based on the information provided by the customer (user). In order to shorten TAT (Turn Around T me), the wafer manufacturing process is often used to plan the project. (P r gram), but its disadvantage is that the memory cell has a larger area, which is less suitable for economic requirements. Therefore, the present invention is directed to the above-mentioned problem, and proposes a data writing engineering method of a photomask type read-only memory, which can not only reduce the area required for an effective cell, but also reduce the bit cost. ;)versus

1232552 V. Description of the invention (2) The size of the die under the required density conditions to solve the above problems. [Summary of the invention] The main purpose of the present invention is to provide a mask type read-only memory data Write method to achieve the purpose of effectively reducing the memory cell area. Another object of the present invention is to provide a data writing method of a mask type read-only memory, so as to effectively reduce the size of crystal grains under a desired density condition. Another object of the present invention is to provide a data writing method of a mask type read-only memory, so as to achieve the purpose of effectively reducing the bit cost. To achieve the above object, the present invention provides a data writing method of a photomask type read-only memory, which includes the following steps: providing a semiconductor substrate having a plurality of gate structures; forming a patterned first photoresist layer And patterning the first photoresist layer on the semiconductor substrate to cover the gate structure to expose the first coding region; and then using the patterned first photoresist layer as a mask to perform the first ionization on the first coding region An implantation step, and then removing the patterned first photoresist layer; then forming a cover, a gate structure and the first coding region on the semiconductor substrate, and exposing the patterned second photoresist layer of the second coding region; Then, using the patterned second photoresist layer as a mask, a second ion implantation step is performed on the second coding region, and then the patterned second photoresist layer is removed; and a patterned third is formed on the semiconductor substrate. Photoresistive layer, which covers the gate structure, the first coding area and the second coding area, and exposes the third coding area; using the patterned third photoresist layer as a screen, the third coding area is subjected to the third Ion implantation step and then remove The patterned third photoresist layer is finally formed on a semiconductor substrate

1232552 V. Description of the invention (3) A patterned fourth photoresist layer covering the gate structure, the first coding region, the second coding region, the third coding region, and the fourth coding region is exposed; The resist layer is a mask, and a fourth ion implantation step is performed on the fourth coding region; the patterned fourth light group layer is removed, and data writing is completed. The invention further provides a data writing method of a photomask-type read-only memory, which includes the following steps: a semiconductor substrate having a plurality of gate structures; and forming a gate-covering structure on the semiconductor substrate and exposing Patterning the first photoresist layer in the first and fourth coding regions; using the patterned first photoresist layer as a mask, performing a first ion implantation step, and then removing the patterned first photoresist layer A patterned photoresist layer is formed on the semiconductor substrate, wherein the patterned second photoresist layer covers the gate structure and the first coding region, and exposes the second coding region and the fourth coding region; The patterned second photoresist layer is a mask, and the second ion implantation step is performed, and then the patterned second photoresist layer is removed; and a patterned third photoresist layer is formed on the semiconductor substrate to cover the gate structure. , The first coding region, the second coding region, the fourth coding region, and the third coding region is exposed; using the patterned third photoresist layer as a mask, the third ion implantation step is performed; and finally the pattern is removed The third photoresist layer is completed Data is written. In order to make your review members better understand and understand the structural features and achieved effects of the present invention, I would like to refer to the preferred embodiment diagrams and detailed descriptions as follows: [Implementation Mode]

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1232552 V. Description of the invention (5) The third photoresist layer 30 is patterned. Then, a patterned fourth photoresist layer 36 is formed on the semiconductor substrate 12 using a fourth photomask 34 as shown in the second (d) diagram, as shown in the first (d) diagram, where the The patterned fourth photoresist layer 36 covers the gate structure 10, the first coding region, the second coding region, and the third coding region, and exposes the fourth coding region to pattern the fourth photoresist layer 36. For an implant mask, a fourth ion implantation step is performed to form a fourth ion implantation region 3 8 located at the gate channel 18, and finally the patterned fourth light group layer 36 is removed to complete the data. The writing process. Among them, during the first ion implantation step, the ion implantation dose can be 1.OOE + 14 / cm2, and the obtained critical voltage is 2.9Vt, and the second ion implantation dose is 1 50E + 14 / cm2, the obtained critical voltage is 3.6Vt, the third ion implantation dose is 2. 00 E + 14 / cm2, the obtained critical voltage is 4.3Vt, and the fourth ion implantation The dose can be taken from any two ion implantation amounts, so as shown in the third figure, different voltage values can be obtained with different doses, so it can be based on different Voltage which is set by the representative sequence (01), (10), (11), (00) bits. When the fourth ion implantation dose is set to be the first ion implantation dose and the second ion implantation dose, the fourth photomask can be combined and designed in the first photomask and the second photomask, and the photomask design will be The first mask 40 shown in the fourth (a), the second mask 42 shown in the fourth (b), and the third mask 44 shown in the fourth (c). Therefore, a second data writing method is derived, which is formed on a semiconductor substrate 12 having a plurality of gate structures 10 to form a patterned first photoresist layer.

1232552 V. Description of the invention (6) 4 6 As shown in the fifth (a) diagram, the patterned first photoresist layer 4 6 uses the first photomask 40 shown in the fourth (a) diagram. It is formed and covers the gate structure 10, and the first coding region and the fourth coding region are exposed, and then the patterned first photoresist layer 46 is used as an implant mask to perform the first ion implantation. In the step, the first ion implantation region 48 and the fourth ion implantation region 50 located in the gate channel 18 are formed, and then the patterned first photoresist layer 46 is removed. Then, a second patterned photoresist layer 52 is formed on the semiconductor substrate 12, as shown in FIG. 5 (b), wherein the second patterned photoresist layer 52 is used as shown in FIG. 4 (b). The second photomask 42 is formed and covers the gate structure 10 and the first coding region, and exposes the second coding region and the fourth coding region. The second photoresist layer 52 is patterned as an implant mask. To perform a second ion implantation step to form a second ion implantation region 54 located in the gate channel 18 and a fourth ion implantation region 50 added with a second ion implantation dose, and remove the patterning Second photoresist layer 5 2. Next, a third photoresist layer 44 as shown in FIG. 4 (c) is used to form a patterned third photoresist layer 56 on the semiconductor substrate 12, while referring to FIG. 5 (c), which covers the gate The pole structure 10, the first coding region, the second coding region and the fourth coding region, and the third coding region is exposed. The patterned third photoresist layer 56 is used as an implant mask for the third ion implantation. In the step, a third ion implantation region 58 is formed in the gate channel 18, and the patterned third photoresist layer 56 is removed to complete the data writing process. In summary, the present invention is a data writing engineering method of a photomask type read-only memory, which uses the ion implantation amount to set different voltage values as (0 1), (1 0), ( 0 0) and (1 1) double-bit storage mode, which can

Page 10 1232552 V. Description of the invention (7) Reduce the overall chip area, reduce the cost of the process, and speed up the reading speed of its data. However, the above is only a preferred embodiment of the present invention, and is not intended to limit the scope of implementation of the present invention. Therefore, for example, changes in shape, structure, characteristics, and spirit in accordance with the scope of the patent application for the present invention are equivalent. Modifications should be included in the scope of patent application of the present invention. [Illustration of figure number] 10 gate structure 12 semiconductor substrate 14 first photomask 16 patterned first photoresist layer 1 8 gate channel 2 0 first ion implantation region 22 second photomask 2 4 patterned first Two photoresist layers 2 6 Second ion implantation area 28 Third photomask 3 0 Patterned third photoresist layer 3 2 Third ion implantation area 3 4 Fourth photomask 3 6 Patterned fourth photoresist layer 3 8 Fourth ion implantation region 40 First photomask 42 Second photomask

1232552 V. Description of the invention (8) 4 4 Third photomask 4 6 Patterned first photoresist layer 4 8 First ion implanted area 50 Fourth ion implanted area 5 2 Patterned second photoresist layer 5 4th Two ion implantation area 5 6 patterned third photoresist layer 5 8 third ion implantation area

Page 12 1232552 Brief description of the drawings The first (a) to the first (d) diagrams are cross-sectional structural views of each step when the invention uses four photomasks to write data. Figures 2 (a) to 2 (d) are the design patterns of the four photomasks when using the four photomasks to write data according to the present invention. The third graph is the change of the relative voltage under different ion implantation doses of the present invention. The fourth (a) to fourth (c) diagrams are respectively the mask design patterns when the invention uses three kinds of masks for data writing.

Fifth (a) to fifth (c) are cross-sectional views of the steps of the present invention when using three photomasks for data writing.

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Claims (1)

1232552 _ Case No. 92130792_ 年月 日 __ VI. In the patent application area, using the patterned fourth photoresist layer as a screen, perform a fourth ion implantation step on the fourth coding area; and remove the Patterning a fourth light group layer. 2 · The data writing method of the photomask type read-only memory as described in item 1 of the scope of the patent application, wherein the dose of the first ion implantation is 1. 00 E + 1 4 / cra 2 0 3 The data writing method of the mask type read-only memory according to item 1 of the patent scope, wherein the second ion implantation dose is 1.50 E + 1 4 / cm 2〇4. The data writing method of the mask type read-only memory according to the above item, wherein the dose of the third ion implantation is 2. 00E + 1 4 / cm 2 0 · The photomask as described in item 1 of the scope of patent application A method for writing data in a read-only memory, wherein the fourth ion implantation dose may be a sum of the first double bit coded implantation and the second bit coded implantation dose. 6. The data writing method of the mask type read-only memory as described in item 1 of the scope of patent application, wherein when the first ion implantation step is performed, the ions are implanted in the gate channel. 7. The data writing method of the mask type read-only memory according to item 1 of the scope of the patent application, wherein when the second ion implantation step is performed, the ions are implanted in the gate channel. 8. The data writing method of the mask type read-only memory as described in item 1 of the scope of patent application, wherein when the third ion implantation step is performed, the ion Page 15 1232552 _ Case No. 92130792 _ Month and Day __ VI. The scope of patent application is implanted in the gate channel. 9 · The data writing method of the mask type read-only memory as described in item 1 of the patent application scope, wherein when the fourth ion implantation step is performed, the ions are implanted in the gate channel. 1 0 · —A method for writing data in a photomask type read-only memory, which includes the following steps: a semiconductor substrate having a plurality of gate structures thereon; Forming a patterned first photoresist layer on the semiconductor substrate, wherein the patterned first photoresist layer covers the gate structure and exposes a first coding region and a fourth coding region; and patterning the first The photoresist layer is a mask, performing a first ion implantation step, and then removing the patterned first photoresist layer; forming a patterned second photoresist layer on the semiconductor substrate, wherein the patterned second light The resist layer covers the gate structure and the first coding region, and exposes the second coding region and the fourth coding region. The patterned second photoresist layer is used as a mask to perform a second ion implantation step, and then Removing the patterned second photoresist layer; A patterned third photoresist layer is further formed on the semiconductor substrate, wherein the patterned third photoresist layer covers the gate structure, the first coding region, the second coding region, and the fourth coding region and is exposed. The second coding region uses the patterned third photoresist layer as a mask to perform a third ion implantation step; and removes the patterned third photoresist layer. 1 1 · Material of mask type read-only memory as described in item 10 of the scope of patent application Page 16 1232552 _Case No. 92130792_year month__ Sixth, the scope of patent application material writing method, wherein the first ion implantation dose is 1. 00 E + 14 / cm2. 1 2 · The data writing method of the photomask type read-only memory as described in item 10 of the scope of the patent application, wherein the second ion implantation dose is 1.50 E + 1 4 / cm 2 0 1 3 00E + 1 4 / cm 2〇 The data writing method of the photomask type read-only memory as described in item 10 of the patent application scope, wherein the dose of the third ion implantation is 2. 00E + 1 4 / cm 2〇 14 · The data writing method of the mask read-only memory as described in item 10 of the scope of patent application, wherein when the first ion implantation step is performed, the ions are implanted in the gate channel. 15 · The data writing method of the photomask type read-only memory as described in item 10 of the scope of patent application, wherein when the second ion implantation step is performed, the ions are implanted in the gate channel. 16. The data writing method of the mask type read-only memory according to item 10 of the scope of the patent application, wherein when the third ion implantation step is performed, the ions are implanted in the gate channel. Page 17