CN101202226B

CN101202226B - Integrated method for improving metal former medium PMD filling characteristic

Info

Publication number: CN101202226B
Application number: CN200610119408A
Authority: CN
Inventors: 陈昊瑜; 龚顺强; 缪炳有
Original assignee: Shanghai Hua Hong NEC Electronics Co Ltd; Shanghai Integrated Circuit Research and Development Center Co Ltd
Current assignee: Shanghai IC R&D Center Co Ltd; Shanghai Huahong Grace Semiconductor Manufacturing Corp
Priority date: 2006-12-11
Filing date: 2006-12-11
Publication date: 2010-05-12
Anticipated expiration: 2026-12-11
Also published as: CN101202226A

Abstract

The invention discloses an integration method for enhancing the filling characteristic of a metal antemedium PMD. The method of the invention includes: firstly a layer of a heated oxidation film is generated on a silicon basic board; a layer of polysilicon (1) is settled for etching; silicon nitride or silicon oxide is settled to form a side wall after etching; after the forming of the side wall,SiN is settled as a liner (5); finally BPSG is settled; however, the appearance of the side wall formed by the invention is inclined; the inclined appearance of the side wall can lead the polysiliconbottom to be provided with an inclined appearance of about 80 degrees angle through changing the etching conditions of the polysilicon or lead the shoulder of the side wall to fall down to form the inclined appearance of the side wall through increasing the ratios of anisotropic etching in the side wall etching process. The invention can compensate the defects or limits of the filling capability of BPSG process, so as to avoid the emergence of PMD void. The invention can be applied to the integration process of semiconductors which is of 0.18 microns or less than 0.18 microns.

Description

A kind of integrated approach that improves metal former medium PMD filling characteristic

Technical field

The present invention relates to a kind of semiconductor fabrication process, relate in particular to a kind of integrated approach that improves metal former medium PMD filling characteristic.

Background technology

Before-metal medium layer PMD generally is made up of three layers of medium, as liner SiN (silicon nitride) or SiON (silicon oxynitride)+BPSG (Borophosphosilicate glass, boron phosphor silicon oxide)+SiO ₂(silicon dioxide) or SiON.The main effect of liner SiN or SiON is to stop B (boron) and P (phosphorus) to be diffused into silicon substrate, thereby influences device performance; The effect of BPSG is a gettering---absorb or catch from the metal ion/hydrogen ion of postchannel process and other impurity, prevent to be diffused into silicon substrate; Surface SiO ₂The main effect of (silicon dioxide) or SiON is that protection BPSG acidifying/boron phosphorus is separated out.Usually industrial quarters adopts SA (inferior normal pressure) BPSG.

Along with reducing of device size, the filling a vacancy property of BPSG becomes one of focus of industry concern before the metal.In 0.18um and following technology, special in containing the storage component part technology of double level polysilicon, the aspect ratio logical device height of polysilicon, and the spacing between the polysilicon is dwindled, both ratio is bigger.The filling a vacancy property of original SA BPSG is subjected to challenge (having the cavity to occur), maybe can not satisfy technological requirement; Because should the cavity if appear at the sidewall of interconnected pores, barrier layer Ti/TiN can not cover the cavity, in the deposition process of tungsten plug, can etching sidewall BPSG from the F ion of gas WF6, thus may cause interconnect failure and device performance reduction etc.Because the requirement of filling a vacancy property, people also adopt HDP PSG (high-density plasma is mixed phosphor silicon oxide), and this filling a vacancy property of technology is good; But its shortcoming is a technology cost height.So unless have no alternative but, people always select the lower-cost SA BPSG of technology.In order to prolong the technology life-span of SA BPSG, people always try every means and improve the filling a vacancy property of PMD integral body.In general, PMD the cavity occurs and has following five reasons at least: the ability of filling a vacancy of SA BPSG technology itself has much room for improvement or optimizes; BPSG's covers type sexual needs optimization; Liner SiN or SiON technology have to be optimized; Annealing process needs to optimize; Silicide process needs to optimize.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of integrated approach that improves metal former medium PMD filling characteristic, remedies the deficiency or the finiteness of the filling capacity of BPSG technology own, thereby avoids the generation in PMD cavity.

For solving the problems of the technologies described above, the present invention improves the integrated approach of the preceding medium filling characteristic of metal, and described before-metal medium layer is made up of three layers of medium, and described three layers of medium are respectively liner, BPSG, SiO ₂Or SiON, described integrated approach comprises: one deck heat oxide film of at first growing on silicon substrate; Deposit one deck polysilicon and carry out etching again; Deposit silicon nitride or silica form side wall after the etching; Form behind the side wall deposit SiN or SiON as liner, last deposit BPSG; But it is what tilt that the present invention forms the pattern of side wall; The pattern that forms side wall can be by changing the etching condition of polysilicon for what tilt, and making the polysilicon bottom have angle is inclination pattern about 80 degree; Also by increasing the ratio of anisotropic etching in the side wall etching, the pattern that makes the decline of side wall shoulder position form side wall tilts.The inventive method can be applicable to 0.18 micron and following semiconductor integrated technique.

The inventive method has improved the type that covers of BPSG owing to change two kinds of etching technics menus, can improve the rate of finished products and the reliability of corresponding product.

Description of drawings

Fig. 1 is the formation step of PMD under the traditional handicraft method;

Fig. 2 is the formation step of PMD under the inventive method;

Reference numeral: 1, polysilicon, 2, heat oxide film, 3, silicon substrate, 4, side wall, 5, liner, 6, BPSG.

Embodiment

The present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.

At first tell about principle of the present invention.The filling step of BPSG is as follows in traditional semiconductor technology: 1, on liner SiN or SiON at first deposit cover the type film; 2, deposit is filled to intermediate gaps from film on every side; 3, make BPSG reflow through thermal annealing, further fill the gap.In 0.18 micron technology, in order to reduce the influence of thermal process to device, thermal annealing after the BPSG deposit from before stove annealing (general 700-800 degree, about 30 minutes time) change rapid thermal anneal process (general～700 degree /～30 seconds) into, rapid thermal anneal process RTP does not almost have too big improvement to the filling a vacancy property of BPSG technology under this kind situation; In addition, by adjusting the B/P ratio in the BPSG technology, can optimize the porefilling capability of BPSG itself; But because BPSG grows up and its to cover type relevant, isolate in the mortise at the polycrystalline of high depth-width ratio, if the pattern of side wall itself is steep, can make BPSG in filling process, form a sealing cavity, the above-mentioned BPSG of improvement process conditions and annealing conditions all can't thoroughly be eliminated the cavity, at this situation, we have proposed novel integrated approach at the optimization that BPSG covers type.Promptly the side wall pattern of Qing Xieing can reduce to form the probability in sealing cavity, provides a kind of new PMD integrated approach as starting point, to satisfy 0.18 micron and following technological requirement.And the side wall pattern that will obtain tilting can be realized from following two kinds of methods: 1, directly optimize the side wall etching condition, and form the pattern of inclination as far as possible.This can make it that side wall shoulder position is descended and obtain by increasing the ratio of anisotropic etching in the side wall etching; 2, change the etching polysilicon condition, make it form the pattern (as figure) that tilts, also helpful to obtaining the side wall pattern.This polycrystalline silicon etching process can be used for reference the lithographic method that the short groove of ditch is isolated (STI), makes it form the preceding dielectric isolation mortise of the metal that tilts.Comprise: change the pattern of polycrystal etching and the pattern of side wall etching.

Fig. 1 is the formation step of PMD under the traditional handicraft method; As shown in the figure, long one deck heat oxide film 2 on silicon substrate 3 at first; Deposit one deck polysilicon 1 again; Be the etching of polysilicon then; Deposit side wall nitride silicon and silica form side wall 4 after the etching; Side wall forms back deposit SiN as liner 5, last deposit BPSG 6.The pattern of side wall is steep among Fig. 1, forms the sealing cavity easily.

Fig. 2 then is the formation step of PMD under the inventive method.Be that with the difference of traditional approach among Fig. 1 the change of polycrystal etching and side wall etching to form the pattern of inclination, helps the filling of BPSG.The present invention selects the etching polysilicon at 80 degree angles of inclination for use; Can use for reference the lithographic method of ripe shallow trench isolation (STI); Reduced technology difficulty.

Tell about the present invention below in conjunction with embodiment.

Embodiment one: what adopt this method in the present embodiment is that a kind of double-layered polycrystal thickness is the storage component part of 3500A (dust) altogether.Be spaced apart 0.54um between its polycrystalline, the structure of side wall (Spacer) is the SiO of 100A ₂Add the SiN of 1000A.Under traditional PMD formation method, be easy to occur cavity (Void).Adopt SiN among the EMAX base station etching Spacer in an embodiment, increase anisotropic etching gas, thereby can realize the spacer pattern that tilts.And type is covered in the BPSG that the spacer pattern that tilts improves filling, thereby has solved the Void problem.

Embodiment two: if the design rule of device further reduces, in order further to improve the filling characteristic of PMD, can increase the etching angle of polysilicon (Poly), consider the control problem of CD after the Poly etching, the etching angle of Po1y is decided to be about 80 degree, similar with the etching angle of short trench isolations (STI). use for reference the etching condition of STI, promptly in the poly etching, increase etching polymer, increasing the O2 content in the etching gas, can realize the pattern of poly etching rear-inclined. its result also is the filling capacity that equally helps improving BPSG.

The inventive method can be applicable to 0.18 micron and following semiconductor integrated technique.

Claims

1. integrated approach that improves medium filling characteristic before the metal, described before-metal medium layer is made up of three layers of medium, and described three layers of medium are respectively liner, BPSG, SiO ₂Or SiON, described integrated approach comprises: one deck heat oxide film of at first growing on silicon substrate; Deposit one deck polysilicon and carry out etching again; Deposit silicon nitride or silica form side wall after the etching; Form behind the side wall deposit SiN or SiON as liner, last deposit BPSG; It is characterized in that described deposit one deck polysilicon also carries out changing the etching condition of described polysilicon in the process of etching, make the polysilicon bottom have the inclination pattern that angle is 80 degree;

Described deposit silicon nitride or silica also form after etching in the process of side wall, and by increasing the ratio of anisotropic etching in the side wall etching, the pattern that makes the decline of side wall shoulder position form side wall tilts.

2. the integrated approach that improves the preceding medium filling characteristic of metal according to claim 1 is characterized in that this method is applied to 0.18 micron and following semiconductor integrated technique.