Abstract: The poor uniformity of Interlevel Dielectric Deposition (ILD) thickness for High Aspect Ratio (HAR) contact after Chemical Mechanical Planarization (CMP) will cause serious underlayer loss due to the longer over-etching time that is required to compensate for thickness differences within the wafer. Prior Art uses 1.5K Plasma Enhanced Tetra-Ethyl-Ortho-Silicate (PETEOS) to serve as a stop layer and thus reduce underlayer loss. The present invention teaches using a non-silicon oxide containing SiN/SiON or Si3N4/SiON as a stop layer. The present invention therefore is aimed at reducing underlayer loss and thereby improving the uniformity of the underlayer thickness upon completion of the hole etching process. Concurrently, the over-etch time can be reduced to less than 10% of the time required for Prior Art contact hole etching.

Abstract: This invention provides a method for forming a self aligned contact without key holes using a two step sidewall spacer deposition. The process begins by providing a semiconductor structure having a device layer, a first inter poly oxide layer (IPO-1), and a conductive structure (such as a bit line) thereover, and having a contact area on the device layer adjacent to the conductive structure. The semiconductor structure can further include an optional etch stop layer overlying the first inter poly oxide layer. The conductive structure comprises at least one conductive layer with a hard mask thereover. A first spacer layer is formed over the hard mask and the IPO-1 layer and anisotropically etched to form first sidewall spacers on the sidewalls of the conductive structure up to a level above the bottom of the hard mask and below the level of the top of the hard mask such that the profile of the first sidewall spacers are not concave at any point.

Abstract: A new method based on measuring the weight of a wafer (on which the layer of HSG has been deposited) before (W1) and after (W2) the surface of the HSG layer is coated with a layer of either photoresist or SOG. The difference delta W=W2−W1 provides an indicator of the roughness or smoothness of the surface of the deposited layer of HSG. This new method can also be based on measuring the weight W of rejected or dropped PR or SOG after the surface of the HSG layer has been coated with a layer of either photoresist or SOG. The weight of the rejected or dropped PR or SOG also provides an indicator of the roughness or smoothness of the surface of the deposited layer of HSG.

Abstract: A new method is provided to create a gradated dopant concentration in the contact plug of DRAM devices whereby a high dopant concentration is present at the bottom of the plug and a low dopant concentration is present at the top of the plug. Two layers of dielectric are deposited; the upper layer serves as a layer to adjust the dopant concentration in the lower layer. This adjustment is done by Rapid Thermal anneal of both layers of dielectric. After the dopant concentration has been adjusted, the upper layer of dielectric is removed and the upper section of the contact node is formed using lightly doped poly. The high dopant concentration at the bottom of the contact plug results in low contact resistance between the plug and the underlying silicon substrate. A low dopant concentration at the top surface of the contact plug results in low oxidation of the surface of the plug.

Abstract: A method for reducing the high aspect ratios, encountered when forming, and filling, narrow diameter contact holes, in thick insulator layers, has been developed, featuring a two step contact hole opening and filling procedure. First, lower narrow diameter contact holes are opened in lower levels of insulator layers, then filled with tungsten. After deposition of upper levels of insulator layers, upper narrow diameter contact holes are formed, exposing the tungsten filled, lower diameter contact holes. A second tungsten layer fills the upper, narrow diameter contact hole, resulting in a final narrow diameter contact hole, in thick insulator layers, formed with reduced aspect ratios, via use of the two contact hole openings, and the two tungsten fill procedures. In addition these procedures allow a damascene, tungsten bit line structure, to be formed in a dual shaped opening, in lower insulator layers.

Abstract: A method for forming a self aligned contact without key holes using a two step contact deposition. The process begins by providing a semiconductor structure having conductive structures (such as bit lines) thereover with sidewalls and having a contact area adjacent to the conductive structures. The conductive structures comprise at least one conductive layer with a hard mask thereover. A spacer layer is formed over the hard mask and the substrate structure and anisotropically etched to form sidewall spacers on the sidewalls of the conductive structure. A second dielectric (IPO) layer is formed over the sidewall spacers, the hard mask, and the substrate structure, whereby the second dielectric layer has a keyhole. A contact opening is formed in the second dielectric layer over the contact area. A first contact layer having poor step coverage is formed in the contact openings and over the second dielectric layer, thereby plugging the keyhole without filling it.

Abstract: A method for making crown capacitors using a new and improved crown etch window process for DRAM cells is described. After forming FETs for the memory cells, a planar first insulating layer (IPO-1) is formed and bit lines are formed thereon. A second insulating layer (IPO-2) is deposited, and a first etch-stop layer and a disposable insulating layer are deposited. Contact openings are etched in the layers to the substrate, and are filled with a polysilicon to form capacitor node contact plugs. The disposable layer is removed to expose the upper portions of the plugs extending above the first etch-stop layer. A second etch-stop layer is deposited and a thick insulating layer is deposited in which capacitor openings are etched over and to the plugs.

Abstract: A process for reducing the aspect ratio, for narrow diameter contact holes, formed in thick insulator layers, used to integrate logic and DRAM memory devices, on the same semiconductor chip, has been developed. The process of reducing the aspect ratio, of these contact holes, features initially forming, via patterning procedures, lower, narrow diameter contact holes, to active device regions, in the logic area, while also forming self-aligned contact openings to source/drain regions in the DRAM memory region. After forming tungsten structures, in the lower, narrow diameter contact holes, polycide bitline, and polysilicon capacitor structures, are formed in the DRAM memory region, via deposition, and patterning, of upper level insulator layers, and polysilicon and polycide conductive layers. Upper, narrow diameter openings, are then formed in the upper level insulator layers, exposing the top surface of tungsten structures, located in the lower, narrow diameter contact holes.

Abstract: A process for forming a DRAM, cylindrical shaped, stacked capacitor structure, located under a bit line structure, has been developed. The process features defining a polysilicon cell plate structure, during the same photolithotgraphic and anisotropic etching procedures, used to open a bit line contact hole. The bit line contact hole is formed by first opening a top portion of the bit line contact hole, using a photoresist shape as an etch mask, and after the formation of silicon nitride spacers, on the sides of the top portion of the bit line contact hole, the bottom portion of the bit line contact hole is opened, using silicon nitride as an etch mask.

Abstract: A method using a two-step contact process for making word-line strapping on DRAM devices was achieved. The method replaces a single-step contact process in which it is difficult to etch the smaller contact openings. After partially completing the DRAM cells by forming gate electrodes and word lines having a first hard mask, a planar first insulating layer is formed. Capacitor node contact openings are etched and capacitors with a protective second hard mask are completed. A thin first photoresist mask with improved resolution is used to etch small first contact openings in the first insulating layer to the word lines, while the second hard mask protects the capacitors from etching. Tungsten plugs are formed in the openings, and an interlevel dielectric layer is deposited over the capacitors. A thin second photoresist mask with improved resolution is used to etch second contact openings to the tungsten plugs.

Abstract: A method of forming a deep contact by forming a dielectric layer 20 over a semiconductor structure 10. A main point is that the hard mask 30 is removed after the plug 52 is formed. A hard mask layer 30 is formed over the dielectric layer 20. A contact photoresist layer 36 is formed over the hard mask layer 30. The hard mask layer 30 is etched through the contact photoresist opening 39 to form a contact hard mask opening 41 exposing the dielectric layer 20. The dielectric layer 20 is etched using a high density plasma etch process using the contact photoresist layer 36 and the hard mask layer 30 as an etch mask forming a contact hole 40 in the dielectric layer 20. The contact photoresist layer 36 is removed. A metal layer 50 is formed filling the contact hole 40 and covering over the hard mask layer 30. The metal layer 50 is etched back forming a plug 52 filling the contact hole 40. Now, the hard mask layer 30 is removed.

Abstract: A process for creating an insulator filled, shallow trench, in a semiconductor substrate, in which the insulator layer in the shallow trench, is not exposed to procedures used to remove defining composite insulator layers, has been developed. The process features creating a lateral recess, in a thick silicon nitride layer, used as a component of a composite insulator layer, where the composite insulator layer is used for subsequent definition of the shallow trench, in the semiconductor substrate.

Abstract: A method to form capacitance node contacts with improved isolation in a DRAM process is described. An isolation layer is formed on a semiconductor substrate. A first contact hole is formed and filled with a polysilicon plug and the top surface of the isolation layer and of the polysilicon plug are polished to a planar surface. A first interpoly isolation layer is deposited. A stopping layer is deposited. A capping layer is deposited. A first polysilicon layer is deposited. The first polysilicon layer is etched to form features. A second interpoly isolation layer is deposited. The second interpoly isolation layer is planarized. The second contact hole is etched through the second interpoly isolation layer and the capping layer. The exposed first polysilicon material is etched back to the vertical sides of the second contact hole. The stopping layer and the first interpoly isolation layer are etched through to the top surface of the polysilicon plug.

Abstract: An improved etching procedure that uses three processing steps to vastly improve HAR opening profile and improved under-layer selectivity. A new three sequence etching process is provided during which a new three-gas plasma etch is to be used. This new etching sequence is preceded by a new main etch that uses three gasses and followed by a new over-etch procedure that uses the same three gasses and etching conditions as the new main etch.

Abstract: A method of improving the deep contact processing window is described. Semiconductor device structures in and on a semiconductor substrate are covered with a dielectric layer. A polysilicon layer is deposited overlying the dielectric layer. The polysilicon layer is etched away where it is not covered by a photoresist mask to form a polysilicon hard mask. A contact opening is etched through the dielectric layer to the semiconductor substrate where the deep contact is to be made where the dielectric layer is not covered by the polysilicon hard mask. Thereafter the photoresist mask is removed. A photoresist layer is deposited overlying the polysilicon hard mask and filling the contact opening. The polysilicon hard mask and the photoresist layer not within the contact opening are polished away wherein the photoresist layer remaining within the contact opening protects the contact opening from contamination during polishing.