US20050221560A1 - Method of forming a vertical memory device with a rectangular trench - Google Patents
Method of forming a vertical memory device with a rectangular trench Download PDFInfo
- Publication number
- US20050221560A1 US20050221560A1 US11/139,450 US13945005A US2005221560A1 US 20050221560 A1 US20050221560 A1 US 20050221560A1 US 13945005 A US13945005 A US 13945005A US 2005221560 A1 US2005221560 A1 US 2005221560A1
- Authority
- US
- United States
- Prior art keywords
- trench
- rectangular
- mask
- memory device
- substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/308—Chemical or electrical treatment, e.g. electrolytic etching using masks
- H01L21/3083—Chemical or electrical treatment, e.g. electrolytic etching using masks characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/01—Manufacture or treatment
- H10B12/02—Manufacture or treatment for one transistor one-capacitor [1T-1C] memory cells
- H10B12/03—Making the capacitor or connections thereto
- H10B12/038—Making the capacitor or connections thereto the capacitor being in a trench in the substrate
- H10B12/0387—Making the trench
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/02—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier
- H01L27/0203—Particular design considerations for integrated circuits
- H01L27/0207—Geometrical layout of the components, e.g. computer aided design; custom LSI, semi-custom LSI, standard cell technique
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/01—Manufacture or treatment
- H10B12/02—Manufacture or treatment for one transistor one-capacitor [1T-1C] memory cells
- H10B12/03—Making the capacitor or connections thereto
- H10B12/038—Making the capacitor or connections thereto the capacitor being in a trench in the substrate
- H10B12/0383—Making the capacitor or connections thereto the capacitor being in a trench in the substrate wherein the transistor is vertical
Definitions
- FIG. 1 is a plane view of partial layout of the conventional mask for defining a trench pattern.
- the mask 10 includes rectangular transparent regions 10 a to define deep trenches in a semiconductor substrate, such as a silicon wafer.
- the imaging layer can be photoresist.
- the predetermined interval is about 50-70 nm, preferably about 60 nm.
- the rectangular trench has a length of about 700-800 nm and a width of about 500-600 nm.
Abstract
A method of forming a vertical memory device with a rectangular trench. First, a substrate covered by a photoresist layer is provided. Next, the photoresist layer is defined by a mask to form a rectangular opening, wherein the mask has two rectangular transparent patterns arranged with a predetermined interval. Next, the substrate is etched using the defined photoresist layer as a mask to form a single rectangular trench and the photoresist layer is then removed. Finally, a trench capacitor and a vertical transistor are successively formed in the rectangular trench to finish the vertical memory device.
Description
- 1. Field of the Invention
- The invention relates to lithography, and more particularly to a mask for defining a rectangular trench and a method of forming a vertical memory device with a rectangular trench by the mask to improve the threshold voltage of transistor shift and increase the alignment process window.
- 2. Description of the Related Art
- With the wide application of integrated circuits (ICs), several kinds of semiconductor devices with higher efficiency and lower cost are produced based on different objectives. Dynamic random access memory (DRAM) is such an important semiconductor device in the information and electronics industry.
- Most DRAMs presently have one transistor and one capacitor in one DRAM cell. Under increased integration, it is needed to shrink the size of the memory cell so as to manufacture the DRAM with higher memory capacity and higher processing speed. A 3-D capacitor structure can reduce its occupation area in the semiconductor substrate, so the 3-D capacitor, such as a deep trench capacitor, is applied to the fabrication of DRAM of 64 megabits and above. Traditional DRAM with a plane transistor covers larger areas of the semiconductor substrate and cannot satisfy demands for high integration. Therefore, use of vertical transistors which can save space is a current trend in fabrication of memory cells.
- When the size of the trench capacitor and the vertical transistor are shrunk due to high integration, the alignment between the active area and the deep trench becomes more important. Unfortunately, misalignment is difficult to avoid in subsequent process. Moreover, the mask used for lithography is subjected to optical limitation, such as optical proximity effect (OPE), increasing the difficulty of lithography. For example, when the light source passes through a desired trench pattern (rectangular trench pattern) on the mask onto the imaging layer, a rounding trench pattern (oval trench pattern) is formed in the imaging layer due to light diffraction.
-
FIG. 1 is a plane view of partial layout of the conventional mask for defining a trench pattern. Themask 10 includes rectangulartransparent regions 10 a to define deep trenches in a semiconductor substrate, such as a silicon wafer. -
FIG. 2 is a plane view of the alignment between the active area and the trench in a semiconductor substrate. InFIG. 2 , deep trenches are defined by themask 10 shown inFIG. 1 . Here, in order to simplify the diagram, only onedeep trench 12 is shown. As mentioned above, OPE makes thetrench 12 has an oval top view, but not a desired top view (rectangular). In addition, when the active area AA is formed, the active area AA is shifted (as the active area AA′) due to misalignment. The misalignment between the active area AA′ and therounding trench 12 changes the overlapping area, shifting the threshold voltage of the vertical transistor (not shown) in thetrench 12 and changing its electrical properties. That is, the alignment process window is narrowed. As a result, the yield of the memory devices is reduced. Moreover, the area of theoval trench 12 is smaller than the rectangular one, reducing the capacitor (not shown) below the vertical transistor in thetrench 12. - Accordingly, an object of the invention is to provide a mask for defining a rectangular trench, wherein a single rectangular trench is defined by at least two rectangular openings.
- Another object of the invention is to provide a method of forming a vertical memory device with a rectangular trench to increase the trench area and the alignment process window for the active area and the trench, thereby preventing the threshold voltage of the transistor of the vertical memory device shift and increasing the capacitance of the capacitor of the vertical memory device.
- Accordingly, a mask is provided for defining a rectangular trench. The mask includes a transparent substrate and a light-shielding layer disposed thereon. The light-shielding layer has at least two rectangular opening patterns arranged with a predetermined interval to define a single trench.
- The transparent substrate can be quartz and the light-shielding layer can be chromium. Moreover, the predetermined interval is about 50-70 nm. Preferably, the predetermined interval is about 60 nm.
- According to another object of the invention, a method of forming a vertical memory device with a rectangular trench is also provided. First, a substrate covered by an imaging layer is provided. Next, the imaging layer is defined by a mask to form a rectangular opening, wherein the mask has at least two rectangular transparent patterns arranged with a predetermined interval. The substrate is etched using the defined imaging layer as a mask to form a single rectangular trench. Thereafter, the imaging layer is removed. Finally, a trench capacitor and a vertical transistor are successively formed in the rectangular trench to finish the vertical memory device.
- The imaging layer can be photoresist. The predetermined interval is about 50-70 nm, preferably about 60 nm. Moreover, the rectangular trench has a length of about 700-800 nm and a width of about 500-600 nm.
- For a better understanding of the present invention, reference is made to a detailed description to be read in conjunction with the accompanying drawings, in which:
-
FIG. 1 is a plane view of partial layout of the conventional mask for defining a trench pattern; -
FIG. 2 is a plane view of the alignment between the active area and the trench in a semiconductor substrate; -
FIG. 3 is a plane view of partial layout of the mask for defining a trench pattern according to the present invention; -
FIGS. 4 a to 4 c are cross-sections showing a method of forming a vertical memory device with a rectangular trench according to the present invention; and -
FIG. 5 is a plane view of the alignment between the active area and the trench in a semiconductor substrate according to the present invention. - A preferred embodiment of the present invention is now described with reference to
FIGS. 3, 4 a-4 c, and 5. - First,
FIG. 3 is a plane view of partial layout of the mask for defining a trench pattern according to the present invention. Themask 20 includes a transparent substrate 20 a and a light-shielding layer 20 b thereon. In this invention, the transparent substrate 20 a can be glass or quartz. The light-shielding layer 20 b can be chromium and has a thickness of about 100-200 nm. In general, the light-shielding layer 20 b is firstly formed on the transparent substrate 20 a by conventional deposition, such as sputtering. Next, themask 20 for defining trenches is completed after lithography and etching are successively performed on the light-shielding layer 20 b to form a plurality ofrectangular opening patterns 20 c therein. - Compared with the prior art, one trench pattern of the invention is defined by at least two
rectangular opening patterns 20 c arranged with a predetermined interval d. Here, the predetermined interval d is about 50-70 nm, preferably about 60 nm. Since there is an interval d between tworectangular opening patterns 20 c serving as an assistant pattern, the rounded edge of the trench pattern due to the optical proximity effect (OPE) can be avoided. That is, it can prevent formation of an oval trench (a trench with an oval top profile). In addition, it is noted that such single trench can be defined by more than two rectangular or square opening patterns where each opening pattern is arranged with a predetermined interval d. -
FIGS. 4 a to 4 c are cross-sections showing a method of forming a vertical memory device with a rectangular trench according to the present invention. First, inFIG. 4 a, asubstrate 30, such as a semiconductor substrate is provided. A pad oxide layer and a pad nitride layer are successively deposited on thesubstrate 30. Here, in order to simplify the diagram, only ablank substrate 30 is shown. Next, animaging layer 22, such as photoresist, is coated on thesubstrate 30. Thereafter, lithography is performed on theimaging layer 22 using themask 20 shown inFIG. 3 to form arectangular opening 31 therein. - Next, in
FIG. 4 b, thesubstrate 30 is etched using theimaging layer 22 having therectangular opening 31 as a mask to form a deeprectangular trench 33 therein. In the invention, the deeprectangular trench 33 has a length of about 700-800 nm and a width of about 500-600 nm. - Finally, in
FIG. 4 c, after theimaging layer 22 is removed, atrench capacitor 35 and avertical transistor 41 are successively formed in the deeprectangular trench 33 by conventional process to finish the vertical memory device, such as dynamic random access memory (DRAM). In this memory device, thetrench capacitor 35 includes abottom electrode 32 formed in thesubstrate 30 near the bottom of the deeprectangular trench 33, and atop electrode 34, such as polysilicon, formed in thelower trench 33. Acapacitor dielectric layer 36 is also disposed in thelower trench 33 and around thetop electrode 34. - Moreover, the
vertical transistor 41 includes source/drain regions gate 44, and agate dielectric layer 42. Thesource region 40 is formed in the active area AA′ of thesubstrate 30 near the top of thecapacitor 35 and thedrain region 46 is formed near the top of thesubstrate 30. Thegate 44, such as polysilicon, is formed in theupper trench 33. Thegate dielectric layer 42, such as thermal oxide, is disposed between the source/drain regions gate 44. - An insulating
layer 39, such as silicon oxide, is disposed between thegate 44 andtop electrode 34 ofcapacitor 35 to serve as an insulator. Moreover, a collar oxide 38 is disposed over thecapacitor dielectric layer 36. -
FIG. 5 is a plane view of the alignment between the active area AA′ and thetrench 33 in thesubstrate 30, andFIG. 4 c is also a cross-section along I-I line inFIG. 5 . Since thedeep trench 33 is defined by optical proximity correction using themask 20 inFIG. 3 , it has a desired rectangular top view, rather than the oval top profile shown in the prior art. Accordingly, although the active area AA shifts due to misalignment in the subsequent process, as the active area AA′ shown inFIG. 5 , the overlapping area between the active AA′ and the deeprectangular trench 33 is not varied. That is, the threshold voltage shift of the vertical transistor can be prevented, thereby maintaining the electrical properties of the memory device and expanding the alignment process window. Moreover, therectangular trench 33 of the invention has a larger area than the oval one in the prior art. That is, the capacitor formed in therectangular trench 33 can has larger capacitance. - Therefore, according to the method of the invention, the yield can be increased by increasing the alignment process window. Moreover, operation speed can be raised by increasing the capacitance of the trench capacitor.
- While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Claims (9)
1-5. (canceled)
6. A method of forming a vertical memory device with a rectangular trench, comprising the steps of:
providing a substrate covered by an imaging layer;
defining the imaging layer by a mask to form a rectangular opening, wherein the mask has at least two rectangular transparent patterns arranged with a predetermined interval;
etching the substrate using the defined imaging layer as a mask to form a single rectangular trench;
removing the imaging layer; and
forming a trench capacitor and a vertical transistor in the rectangular trench successively to finish the vertical memory device.
7. The method as claimed in claim 6 , wherein the substrate is a semiconductor substrate.
8. The method as claimed in claim 6 , wherein the imaging layer is a photoresist substrate.
9. The method as claimed in claim 6 , wherein the predetermined interval is about 50˜70 nm.
10. The method as claimed in claim 6 , wherein the predetermined interval is about 60 nm.
11. The method as claimed in claim 6 , wherein the rectangular trench has a length of about 700˜800 nm.
12. The method as claimed in claim 6 , wherein the rectangular trench has a width of about 500-600 nm.
13. The method as claimed in claim 6 , wherein the vertical memory device is a dynamic random access memory (DRAM) device.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/139,450 US20050221560A1 (en) | 2002-10-21 | 2005-05-27 | Method of forming a vertical memory device with a rectangular trench |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
TW091124265A TW563180B (en) | 2002-10-21 | 2002-10-21 | Mask for defining a rectangular trench and a method of forming a vertical memory device by the mask |
TWTW91124265 | 2002-10-21 | ||
US10/448,675 US7205075B2 (en) | 2002-10-21 | 2003-05-29 | Method of forming a vertical memory device with a rectangular trench |
US11/139,450 US20050221560A1 (en) | 2002-10-21 | 2005-05-27 | Method of forming a vertical memory device with a rectangular trench |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/448,675 Division US7205075B2 (en) | 2002-10-21 | 2003-05-29 | Method of forming a vertical memory device with a rectangular trench |
Publications (1)
Publication Number | Publication Date |
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US20050221560A1 true US20050221560A1 (en) | 2005-10-06 |
Family
ID=32092029
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/448,675 Expired - Lifetime US7205075B2 (en) | 2002-10-21 | 2003-05-29 | Method of forming a vertical memory device with a rectangular trench |
US11/139,450 Abandoned US20050221560A1 (en) | 2002-10-21 | 2005-05-27 | Method of forming a vertical memory device with a rectangular trench |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/448,675 Expired - Lifetime US7205075B2 (en) | 2002-10-21 | 2003-05-29 | Method of forming a vertical memory device with a rectangular trench |
Country Status (2)
Country | Link |
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US (2) | US7205075B2 (en) |
TW (1) | TW563180B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080185680A1 (en) * | 2006-01-09 | 2008-08-07 | International Business Machines Corporation | Structure and method for making on-chip capacitors with various capacitances |
Citations (7)
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---|---|---|---|---|
US4394437A (en) * | 1981-09-24 | 1983-07-19 | International Business Machines Corporation | Process for increasing resolution of photolithographic images |
US4662059A (en) * | 1985-09-19 | 1987-05-05 | Rca Corporation | Method of making stabilized silicon-on-insulator field-effect transistors having 100 oriented side and top surfaces |
US5876878A (en) * | 1996-07-15 | 1999-03-02 | Micron Technology, Inc. | Phase shifting mask and process for forming comprising a phase shift layer for shifting two wavelengths of light |
US6140673A (en) * | 1995-07-13 | 2000-10-31 | Kabushiki Kaisha Toshiba | Semiconductor memory device and fabricating method |
US6235456B1 (en) * | 1998-12-09 | 2001-05-22 | Advanced Micros Devices, Inc. | Graded anti-reflective barrier films for ultra-fine lithography |
US6294423B1 (en) * | 2000-11-21 | 2001-09-25 | Infineon Technologies North America Corp. | Method for forming and filling isolation trenches |
US6426252B1 (en) * | 1999-10-25 | 2002-07-30 | International Business Machines Corporation | Silicon-on-insulator vertical array DRAM cell with self-aligned buried strap |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR0151427B1 (en) * | 1994-03-04 | 1999-02-18 | 문정환 | Phase shift mask and fabricating method thereof |
US6582260B2 (en) * | 2000-08-25 | 2003-06-24 | Honda Giken Kogyo Kabushiki Kaisha | Outboard engine assembly |
US6444524B1 (en) * | 2000-09-11 | 2002-09-03 | Promos Technologies, Inc. | Method for forming a trench capacitor |
-
2002
- 2002-10-21 TW TW091124265A patent/TW563180B/en not_active IP Right Cessation
-
2003
- 2003-05-29 US US10/448,675 patent/US7205075B2/en not_active Expired - Lifetime
-
2005
- 2005-05-27 US US11/139,450 patent/US20050221560A1/en not_active Abandoned
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4394437A (en) * | 1981-09-24 | 1983-07-19 | International Business Machines Corporation | Process for increasing resolution of photolithographic images |
US4662059A (en) * | 1985-09-19 | 1987-05-05 | Rca Corporation | Method of making stabilized silicon-on-insulator field-effect transistors having 100 oriented side and top surfaces |
US6140673A (en) * | 1995-07-13 | 2000-10-31 | Kabushiki Kaisha Toshiba | Semiconductor memory device and fabricating method |
US5876878A (en) * | 1996-07-15 | 1999-03-02 | Micron Technology, Inc. | Phase shifting mask and process for forming comprising a phase shift layer for shifting two wavelengths of light |
US6235456B1 (en) * | 1998-12-09 | 2001-05-22 | Advanced Micros Devices, Inc. | Graded anti-reflective barrier films for ultra-fine lithography |
US6426252B1 (en) * | 1999-10-25 | 2002-07-30 | International Business Machines Corporation | Silicon-on-insulator vertical array DRAM cell with self-aligned buried strap |
US6294423B1 (en) * | 2000-11-21 | 2001-09-25 | Infineon Technologies North America Corp. | Method for forming and filling isolation trenches |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080185680A1 (en) * | 2006-01-09 | 2008-08-07 | International Business Machines Corporation | Structure and method for making on-chip capacitors with various capacitances |
US7723201B2 (en) | 2006-01-09 | 2010-05-25 | International Business Machines Corporation | Structure and method for making on-chip capacitors with various capacitances |
Also Published As
Publication number | Publication date |
---|---|
US20040076893A1 (en) | 2004-04-22 |
TW563180B (en) | 2003-11-21 |
US7205075B2 (en) | 2007-04-17 |
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Legal Events
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |