Improvements in or relating to semiconductor devices

Abstract: A semiconductor device and method having a low-permittivity material between closely-spaced leads in order to decrease unwanted capacitance, while having a more structurally strong dielectric between widely-spaced leads where capacitance is not as critical. Metal layer 14 is deposited on a substrate 12 of a semiconductor wafer 10 , where the metal layer 14 has a first portion 15 and a second portion 17 . Widely-spaced leads 16 are formed in the first portion 15 of the metal layer 14 , and a first structural dielectric layer 26 is deposited on at least the widely-spaced leads. Closely-spaced leads 18 are formed in the second portion 17 of the metal layer 14 , and low-permittivity material 34 is deposited between closely-spaced leads 18 . A second structural dielectric layer 36 is deposited on at least low-permittivity material 34 and closely-spaced leads 18 . An advantage of the invention includes improved structural strength by placing structurally weak low-permittivity material only where needed, in areas having closely-spaced leads.

Description: Field Of The Invention This invention relates generally to the fabrication of semiconductor devices, and more specifically to the patterning of metallic interconnect layers having submicron spacing and using low-permittivity materials between leads. Background Of The Invention Semiconductors are widely used in integrated circuits for electronic applications, including radios and televisions. Such integrated circuits typically use multiple transistors fabricated in single crystal silicon. Many integrated circuits now contain multiple levels of metallization for interconnections. As geometries shrink and functional density increases, it becomes imperative to reduce the RC time constant within multi-level metallization systems. JP-A-5,160,278 and US-A-5,155,576 disclose devices in which low permittivity dielectric materials are provided between conductors to reduce mutual capacitance there between. Additionally, an interconnection structure is disclosed in IBM Technical Disclosure Bulletin, Vol.34, No.9, page 220 that provides a low permittivity material between conductors that also reduces subsequent stress-induced cracking. Summary Of The Invention Although the dielectric typically used in the past to isolate metal lines from each other was silicon dioxide, recent trends have been towards using materials with low-dielectric constants in order to reduce the RC time constant. Many low-dielectric insulators are either pure polymers (e.g. parylene, teflon, polyimide) or organic spin-on glass (OSOG, e.g. silsequioxane and siloxane glass). The structural strength of these low-permittivity materials is generally poorer than that of silicon dioxide. Thus, the use of low-permittivity materials in the semiconductor industry has resulted in a need for a method of increasing the structural support of a semiconductor wafer. A semiconductor device and method is disclosed herein that solves this problem in a novel fashion. Low-permittivity materials are used only in areas having closely-spaced leads, decreasing unwanted capacitance between closely-spaced leads, while traditional dielectric materials are used elsewhere, providing strong structural support. According to the present invention there is provided a method for patterning a metal layer (14) on a semiconductor substrate (12) comprising: dividing said metal layer (14) into at least a first portion (15) and a second portion (17); forming a plurality of first leads (16) in said first portion (15) of said metal layer (14), the spacing between each first lead (16) and each adjacent first lead (16) being sufficient to substantially prevent capacitive coupling therebetween; depositing a first dielectric layer (26) at least over said plurality of first leads (16), said first dielectric layer (26) being formed from a material having good mechanical strength; forming a plurality of second leads (18) in said second portion (17) of said metal layer (14), the spacing between each second lead (18) and each adjacent second lead (18) being less than one micrometer; depositing a second dielectric layer (34) at least between said plurality of second leads (18), said second dielectric layer (34) comprising a low-permittivity material having a dielectric constant of less than three for substantially preventing capacitive coupling therebetween; and depositing a third dielectric layer (36) over said first dielectric layer (26) and said second dielectric layer (34), said third dielectric layer (36) formed from a material having good mechanical strength. Advantageously a metal layer is deposited on a substrate. The metal layer has a first portion and a second portion. An etch-stopping dielectric layer is deposited on the metal layer, and a resist layer is deposited on the etch-stopping dielectric layer. The resist layer is patterned to form a conductor pattern. The resist layer is removed, and the etch-stopping dielectric layer and metal layer are etched to form metal leads, where widely-spaced leads are formed in the first portion of the metal layer. A low-permittivity material is deposited between the closely spaced leads. A second structural dielectric layer is deposited on the low-permittivity material and the closely-spaced leads. An advantage of the invention includes improved structural strength by placing structurally weak low-permittivity material only where needed, in areas having closely-spaced leads. A further advantage of the invention includes a reduction in fringing capacitance of closely-spaced metal leads. A first structural dielectric layer or etch-stop dielectric layer resides on the metal leads, which results in an increased height of the low-permittivity material on closely-spaced metal leads. This allows the low-permittivity material to extend beyond the top of the metal leads, providing for an increase in process margin. Another advantage of the inventions is that vias to underlying metal leads may be formed through a structurally sound and high quality dielectric material, so that traditional via formation processes can be utilized. Brief Description Of The Drawings In the drawings, which form an integral part of the specification and are to be read in conjunction therewith, and in which like numeral s and symbols are employed to designate similar components in various views unless otherwise indicated: Figures 1A-1D, 2A-2D, and 3A-3D show cross-sections of a portion of a semiconductor device, illustrating several steps in the application of the invention to a typical device; Figures 4A and 4B show a passivating layer deposited over the closely-spaced metal leads; Figures 5A-5e, and 6A-6E show cross-sections of a portion of a semiconductor device, illustrating several steps in the application of an alternative embodiment of the invention to a typical device; Figures 7A-7C show top views of a wafer and possible patterning configurations for the metal layer. Detailed Description of Preferred Embodiments The making and use of the presently preferred embodiments are discussed below in detail. Corresponding numerals and symbols in the different figures refer to corresponding parts unless otherwise indicated. Table 1 below provides an overview of the elements of the embodiments and the drawings. Drawing Element Preferred or Specific Examples Generic Term Other Alternate Examples or Descriptions 10 Semiconductor wafer 12 Silicon oxide over single-crystal silicon Substrate May include other metal layers or other semiconductor elements, (e.g. transistors, diodes); Compound semiconductors (e.g. GaAs, InP, Si/Ge, SiC) may be used in place of Si. 14 Aluminum alloy Metal layer Trilayer of TiN/AlCu/TiN; Alloys of Al, Cu, Mo, W, Ti, Si; Polysilicon, silicides, nitrides, carbides; AlCu alloy with Ti or TiN underlayers; Metal layer. 15 First portion of metal layer 14 First portion of metal layer 14 where widely-spaced leads 16 will be formed 16 Widely-spaced leads 17 Second portion of metal layer 14 Second portion of metal layer 14 where closely-spaced leads 18 will be formed 18 Closely-spaced leads 20 IX725 First resist layer Electron resist; other resists or photoresists; light-sensitive polyimide. Portions may act as a first mask for second portion of metal layer 15 22 First reticle Contains pattern for widely-spaced leads 16. 24 Exposed portions of first resist layer 20 26 SiO 2 First structural dielectric layer Oxide, nitride, dense glass, solid inorganic, solid organic, other suitable rigid dielectric; oxide. 28 Second resist layer Electron resist; other resists or photoresists; light-sensitive polyimide. Portions may act as a second mask for first structural dielectric layer overlying first portion 15 of metal layer. 30 Second reticle Contains pattern for closely-spaced leads 18. 32 Exposed portions of second resist layer 28 34 Parylene Low-permittivity material Other polymer dielectrics such as teflon, aerogel, airgap (inert gases or vacuum). 36 PETEOS (Plasma-enhanced tetraethoxysilane) Second structural dielectric layer Silsesquioxane; SOG (spin-on glass); other oxides. 38 Passivating layer Oxide or nitride layer 39 Silicon nitride/silico n dioxide Etch-stopping dielectric layer Silicon dioxide 40 First metal pattern Used to block closely-spaced leads area 17. 42 Second metal Used to pattern closely-spaced leads 18. 26 SiO 2 First structural dielectric layer Oxide, nitride, dense glass, solid inorganic, solid organic, other suitable rigid dielectric; oxide. 28 Second resist layer Electron resist; other resists or photoresists; light-sensitive polyimide. Portions may act as a second mask for first structural dielectric layer overlying first portion 15 of metal layer. 30 Second reticle Contains pattern for closely-spaced leads 18. 32 Exposed portions of second resist layer 28 34 Parylene Low-permittivity material Other polymer dielectrics such as teflon, aerogel, airgap (inert gases or vacuum). 36 PETEOS (Plasma-enhanced tetraethoxysilane) Second structural dielectric layer Silsesquioxane; SOG (spin-on glass); other oxides. 38 Passivating layer Oxide or nitride layer pattern 44 First reticle of third embodiment Contains patterns for both widely- and closely-spaced leads. 46 First resist layer of third embodiment Photoresist 48 Exposed portions of first resist layer of third embodiment 50 Photoresist Second resist layer of the third embodiment Photo-sensitive polyimide Figures 1-3 show an embodiment of the present invention. Figure 1A shows a semiconductor wafer 10 that has a substrate 12 which may, for example, contain transistors, diodes, and other semiconductor elements (not shown) as are well known in the art. Semiconductor wafer 10 may also contain metal layers. Metal layer 14 has been deposited over the substrate 12. Metal layer 14 may comprise, for example, an aluminum alloy or a titanium-tungsten/aluminum alloy bilayer and is typically from .5 to 2 µm thick. In this invention, metal layer 14 has been divided into two sections; a first portion 15 where widely-spaced leads will be formed, and a second portion 17 where closely-spaced leads will be formed. Figure 1B shows a first resist layer 20 that has been deposited over metal layer 14. The wafer is then masked with a predetermined pattern, with first reticle 22. First reticle 22 is configured such that only the widely-spaced leads 16 will be patterned; the areas of metal layer 14 that will eventually be closely-spaced leads (second portion 17 of metal layer 14 ) are not patterned at this time. Uncovered portions of the first resist layer 20 are exposed as shown in Figure 1B. Exposed portions 24 of the first resist layer 20 are developed and then removed. The metal layer 14 is then etched to form widely-spaced leads 16 as shown in Figure 1C. Widely-spaced leads 16 may typically have a spacing aspect ratio of less than one. (The spacing aspect ratio is the height of the metal lead compared to [i.e. divided by] the space between leads.) Generally, the widely-spaced leads 16 are spaced apart at distances typically one and one-half the minimum lead-to-lead spacing or greater. The spaces between such widely-spaced leads 16 are sufficient to prevent excessive capacitive effects, and thus do not require low-permittivity materials for isolation. Then the first resist layer 20 is stripped, resulting in the structure shown in Figure 1D. At this point, widely-spaced leads 16 have been formed, while the second portion 17 of metal layer 14 where closely-spaced leads will be formed remains unetched. Next, first structural dielectric layer 26 is deposited on metal layer 14, as shown in Figure 2A. This dielectric material may flow in a pattern similar to the topography of the metal beneath it, forming waves, or bumps, and is typically .25 to 2 µm thick on top of the metal layer 14 and widely-spaced metal leads 16. Then the first structural dielectric layer 26 may be planarized, preferably globally planarized by CMP (chemical-mechanical polishing) as shown in Figure 2B. Second resist layer 28 is deposited over the first structural dielectric layer 26. Then a second reticle 30 containing the pattern for the closely-spaced leads 18 is placed over the wafer 10 . The uncovered portions of the second resist layer 28 are exposed as shown in Figure 2C Exposed portions 32 of the second resist layer 28 are developed and then removed. The first structural dielectric layer 26 and metal layer 14 are then etched (generally in two separate etches) to form closely-spaced leads 18 as shown in Figure 2D. For example, the SiO 2 may be etched using a CHF 3 RIE (reactive ion etch) and then the metal layer 14 may be etched with BCl 3 in a separate etch process. Closely-spaced leads 18 typically have a spacing aspect ratio in the range of greater than or equal to one. Generally, closely-spaced leads 18 are spaced apart at distances typically less than one µm, and the spacing can be the same as the minimum lead (conductor) width. The spaces between the leads are dose enough together to possibly have significant parasitic capacitance, and thus the structure would benefit from a dielectric layer containing a low-permittivity material for a dielectric material. Then the second resist layer 28 is stripped, resulting in the structure shown in Figure 3A. At this point, closely-spaced leads 18 have been formed. Next, low-permittivity material 34 is deposited on the wafer, either partially filling or completely filling the spaces between the closely-spaced leads 18 as shown in Figure 3B . The low-permittivity material 34 is comprised of a material having a low-dielectric constant, preferably a polymer dielectric such as parylene or teflon with a dielectric constant of less than approximately 3 . The low-permittivity material 34 is then removed, e.g. etched back (possibly with a timed etch), ( Figure 3C ) to a level at or below the top of first dielectric layer 26. In this embodiment, the low-permittivity material 34 should preferably not be etched down past the top of the closely-spaced metal leads 18. Preferably, the low-permittivity material 34 lies a distance equal to 30-50% the thickness of the metal lead 18 above the top of the closely-spaced metal leads 18 , to eliminate or reduce the fringing capacitance between metal leads 18 at the corners and tops of closely-spaced metal leads 18. The reduction of fringing capacitance is an advantage of this embodiment, which is a result of the increased height of the low dielectric layer 34, which may extend beyond the top of the closely-spaced metal leads 18 . Finally, a second structural dielectric layer 36 is deposited over both the widely-spaced and closely-spaced leads ( 16,18 ) as shown in Figure 3D . Preferably, PETEOS (plasma-enhanced tetraethoxysilane) is used for the second structural dielectric layer 36. Figure 4A shows further processing steps that may be applied, after the step shown in Figure 3A, a passivating layer 38 is formed on exposed portions of first structural dielectric layer 26 and sidewalls of closely-spaced metal leads 18. This passivating layer 38 is beneficial because it prevents reaction between the metal leads 18 and the low-permittivity material 34. Subsequent steps shown in Figures 3B to 3D are performed to form the resulting suture shown in Figure 4B. Next, alternative embodiment of the invention will be described, as depicted in Figures 5 to 6. Figure 5A shows a semiconductor wafer 10 which includes a metal layer 14 deposited over a substrate 12. Again, metal layer 14 has been divided into two sections; a first portion 15 where widely-spaced leads will be formed, and a second portion 17 where closely-spaced leads will be formed. An etch-stopping dielectric layer 39, e.g. low-dielectric organic spin-on-glass (OSOG), is applied over the metal layer 14 . A first resist layer 46 of the third embodiment is then deposited over metal layer 14 . The first resist layer 46 is preferably comprised of photoresist, or other resists such as photosensitive polyimide may be used. The wafer 10 is masked with the first reticle 44 of the third embodiment, which contains the conductor pattern. The first reticle 44 is configured such that both widely-spaced and closely-spaced leads will be patterned at the same time. Uncovered portions of the first resist layer 46 are exposed as shown in Figure 5B. Exposed portions 48 of the first resist layer are developed and removed. Etch-stopping dielectric layer 39 and metal layer 14 are etched, typically in separate steps ( Figure 5C ). The first resist layer 46 is stripped, and first structural dielectric layer 26 is deposited over the entire wafer 10 and may then be planarized ( Figure 5D ). Second resist layer 50 of the third embodiment is applied and exposed in a pattern so that the widely-spaced leads 16 of metal layer 14 remain covered with second resist layer 50 ( Figure 5E ). Second resist layer 50 of the third embodiment is preferably comprised of photoresist, but also could comprise a photosensitive polyimide. The first structural dielectric layer 26 is etched from the closely-spaced leads 18 of metal layer 14 ( Figure 6A ). Second resist layer 50 of the third embodiment is then removed ( Figure 6B ). Low-permittivity material 34 is applied over the entire wafer 10 ( Figure 6C ) and etched back to a level at or below the top of etch-stopping dielectric layer 39 ( Figure 6D ). Etch-stopping dielectric layer 39 serves as an etch stop for the low-permittivity dielectric layer 34 etchant. Finally, second structural dielectric layer 36 is deposited over the etch-stopping dielectric layer 39 above closely-spaced metal leads 18, low-permittivity material 34 and possibly over first structural dielectric layer 26 as shown in Figure 6E. Typically, for the third embodiment, first structural dielectric layer 26 and second structural dielectric layer 36 are comprised of an oxide and etch-stopping dielectric layer 39 is comprised of a low-dielectric constant OSOG having a dielectric constant of less than 3. However, other combinations of materials can be used. For example, etch-stopping dielectric layer 39 may be comprised of an oxide, while the first and second structural dielectric layers 26 and 36 can both be Teflon or parylene. The latter combination may be especially compatible with low-permittivity materials 34 comprising aerogel or xerogel. The steps shown in Figure 4A could also be applied. After the first photoresist 46 of the third embodiment is removed (from Figure 5C ), a passivating layer 38 may be formed on sidewalls of both widely-spaced 16 and closely-spaced metal leads 18 (not shown). This passivating layer 38 is particularly beneficial to closely-spaced metal leads 18 because it prevents reaction between the closely-spaced metal leads 18 and the low-permittivity material 34. Figure 7A shows a top level view of the pattern for the portion 17 of the metal layer 14 where the closely-spaced leads 18 will be formed, as depicted in Figures 1-3. The first metal pattern 40 blocks the second portion 17 of the metal layer 14, to protect the area from the first patterning step. The second metal pattern 42 has etch lines that extend slightly beyond the edge of the first metal pattern 40 , to allow for tolerancing mismatch between the first patterning step and the second patterning step. This will prevent shorts and undesired metal in the resulting metal layer formed. It is important to either form a full metal lead or none at all at the edges where the two metal pattems 40 and 42 meet. At least two alternative methods of blocking off the areas where closely-spaced leads will be formed are available. Figure 7B shows a section of leads that contain both widely-spaced 16 and closely-spaced leads 18. One method would be to mask the adjacent portions only of the closely-spaced leads, as shown within the dotted line box in Figure 7B. However, a misalignment problem could be introduced with this method (unless the method of Figures 5A-5E, and 6A-6E is used), since portions of a single metal lead will be formed in two different steps. Alternately, the entire lead could be blocked, for a lead having at least a portion that is closely-spaced, as shown in Figure 7C. This may prevent possible alignment problems that could occur with the method of Figure 7B. The method described of using a two-step metal etch process to form both widely-spaced and closely-spaced leads in a metal layer in order to selectively fill gaps between closely-spaced leads with low-permittivity material can offer definite advantages over the conventional processes. First, the structurally weak low-permittivity material is limited to areas that benefit from it. In the areas where low-permittivity material is not needed, the structural dielectric layer provides more structural support The result is an overall stronger structure, with better heat transfer capability (since the heat transfer of low-permittivity materials is generally poor). Second, although an extra masking step is required in the first embodiment, generally the alignment is not critical and it may, for example, be avoided by blocking the entire lead for closely-spaced leads. Third, the entire metal layer may be patterning at once, eliminating the possible alignment issues of the first embodiment. The reticle that patterns the resist to mask the widely-spaced leads can be relatively easily generated from the reticle in existence for the metal layer. Thus, the implementation of this embodiment may be easier into current process flows. Fourth, the first structural dielectric layer 26 on top of closely-spaced leads 18 in the first and second embodiments, and the etch-stopping dielectric layer 39 on top of closely-spaced leads 18 in the third embodement, have the additional advantage of reducing fringing capacitance between closely-spaced leads 18. These dielectric layers ( 26, 39 ) allow for increased height of the low-permittivity material 34 between closely-spaced leads 18, enabling the low-permittivity material to extend beyond the top of the metal leads. This provides for an increase in process margin. A fifth advantage of the invention is that vias to underlying metal leads may be formed through a structurally sound and high quality dielectric (the first structural dielectric layer 26 on top of closely-spaced leads 18 in the first and second embodiments, and the etch-stopping dielectric layer 39 on top of closely-spaced leads 18 in the third embodiment), so that traditional via formation processes can be utilized.

Claims: A method for patterning a metal layer (14) on a semiconductor substrate (12) comprising: dividing said metal layer (14) into at least a first portion (15) and a second portion (17); forming a plurality of first leads (16) in said first portion (15) of said metal layer (14), the spacing between each first lead (16) and each adjacent first lead (16) being sufficient to substantially prevent capacitive coupling therebetween; depositing a first dielectric layer (26) at least over said plurality of first leads (16), said first dielectric layer (26) being formed from a material having, good mechanical strength; forming a plurality of second leads (18) in said second portion (17) of said metal layer (14), the spacing between each second lead (18) and each adjacent second lead (18) being less than one micrometer; depositing a second dielectric layer (34) at least between said plurality of second leads (18), said second dielectric layer (34) comprising a low-permittivity material having a dielectric constant of less than three for substantially preventing capacitive coupling therebetween; and depositing a third dielectric layer (36) over said first dielectric layer (26) and said second dielectric layer (34), said third dielectric layer (36) being formed from a material having good mechanical strength. The method as claimed in Claim 1, wherein the step of forming a plurality of first leads (16) comprises forming a plurality of first leads (16) having an aspect ratio of less than one. The method as claimed in Claim 1 or Claim 2, wherein the step of forming a plurality of second leads (18) comprises forming a plurality of second leads (18) having an aspect ratio greater than or equal to one. The method as claimed in any preceding claim, wherein the step of forming the plurality of first leads (16) comprises the steps of: forming a first masking layer (20) over said metal layer (14), said first masking layer (20) masking said second portion (17) of said metal layer (14) and providing exposed portions (24) of said first portion (15) of said metal layer (14) in which said plurality of first leads (16) are to be formed; removing exposed portions (24) of said first portion (15) of said metal layer (14) to define said plurality of first leads (16); and removing said first masking layer (20). The method as claimed in any preceding claim, wherein the step of forming the plurality of second leads (18) comprises the steps of: forming a second masking layer (28) over the first dielectric layer (26), said second masking layer (28) masking said first portion (15) of said metal layer (14) and providing exposed portions (32) of said second portion (17) of said metal layer (14) in which said plurality of first leads (16) are to be formed; removing exposed portions (32) of said second portion (17) of said metal layer (14) to define said plurality of second leads (18); and removing said second masking layer (28). The method as claimed in any of Claims 1 to 3, wherein the step of forming the plurality of first leads (16) and the plurality of second leads (18) comprises the steps of: forming a masking layer (46) over said metal layer (14), said masking layer (46) providing exposed portions (48) of said first portion (15) and said second portion (17) of said metal layer (14) respectively in which said plurality of first leads (16) and said plurality of second leads (18) are to be formed; removing exposed portions (48) of said first portion (15) and said second portion (17) of said metal layer (14) to respectively define said plurality of first leads (16) and said plurality of second leads (18); and removing said masking layer (46). The method as claimed in Claim 6 further comprising: prior to the step of forming said masking layer (46), depositing an etch-stop layer (39) over said metal layer (14). The method as claimed in any of Claims 1 to 5 further comprising: forming a passivating layer (38) over the first dielectric layer (26) and the second leads (18) prior to the step of depositing said second dielectric layer (34). The method as'claimed in any preceding claim, wherein the step of forming the second dielectric layer (34) at least between the plurality of second leads (18) comprises the step of providing a second dielectric layer (34) having a surface below a surface of the first dielectric layer (26) and above a surface of the plurality of second leads (18) for substantially eliminating fringing capacitance between adjacent ones of the plurality of second leads (18). The method as claimed in Claim 9, wherein the step of forming the second dielectric layer (34) at least between the plurality of second leads (18) comprises the step of forming the second dielectric layer (34) such that low permittivity material extends along each sidewall of said plurality of second leads (18). The method as claimed in any preceding claim, wherein the step of depositing a second dielectric layer (34) comprises depositing a second dielectric layer (34) formed from a material selected from: polymer dielectrics such as teflon, aerogel, airgap, or PETEOS. The method as claimed in any preceding claim, wherein the step of depositing a third dielectric layer (36) comprises depositing a third dielectric layer (36) such that at least a portion of said third dielectric layer is disposed between each said first or second lead (16;18) and respectively each said adjacent first or second lead (16;18). A semiconductor device comprising: a plurality of first metal leads (16) disposed on a first region (15) of a substrate (12), the spacing between each first lead (16) and each adjacent first lead (16) being sufficient to substantially prevent capacitive effects therebetween; a first dielectric layer (26) at least formed over said plurality of first leads (16), said first dielectric layer (26) being formed from a material having good mechanical strength; a plurality of second metal leads (18) disposed on a second region (17) of said substrate (12), the spacing between each second lead (18) and each adjacent second lead (18) being less than one micrometer; a second dielectric layer (34) at least formed between said plurality of second leads (18) and comprising a low-permittivity material having a dielectric constant of less than three for substantially preventing capacitive coupling between adjacent ones of said plurality of second leads (18); and a third dielectric layer (36) formed over said first dielectric layer (26) and said second dielectric layer (34), said third dielectric layer (36) formed from a material having good mechanical strength. The device as claimed in Claim 13, wherein the plurality of first leads (16) have an aspect ratio of less than one. The device as claimed in Claim 13 or Claim 14, wherein the plurality of second leads (18) have an aspect ratio greater than or equal to one. The device as claimed in any of Claims 13 to 15, wherein the second dielectric layer (34) comprises low permittivity material that extends along each sidewall of said plurality of second leads (18).

Inventors: HAVEMANN ROBERT H, HAVEMANN, ROBERT H.
Applicants: TEXAS INSTRUMENTS INC, TEXAS INSTRUMENTS INCORPORATED
Application year: 1995
Main classification: H01L23
IPC codes: H01L23, H01G4, H01L21