CN101417856A

CN101417856A - Method for preparing phosphorosilicate glass

Info

Publication number: CN101417856A
Application number: CNA2007100941842A
Authority: CN
Inventors: 秦文芳
Original assignee: Shanghai Hua Hong NEC Electronics Co Ltd
Current assignee: Shanghai Huahong Grace Semiconductor Manufacturing Corp
Priority date: 2007-10-26
Filing date: 2007-10-26
Publication date: 2009-04-29

Abstract

The invention discloses a preparation method of phoshosilicate glass, which is characterized in that silane is used as reaction gas, high-density plasma deposition technology is utilized for preparation, and continuous deposition is carried out by using technological conditions of various multi-step deposition sputtering ratios in the process of deposition. During the first-step deposition, the deposition is carried out by using the technological condition of deposition sputtering ratio between 5.7 and 6.7; and then deposition is carried out by using the technological condition of deposition sputtering ratio less than 5.5 in the deposition steps. The preparation method can obviously reduce the horizontal width and vertical height of patterns in phoshosilicate glass layers and is suitable for semiconductor device manufacture.

Description

The preparation method of phosphorosilicate glass

Technical field

The present invention relates to the preparation method of phosphorosilicate glass in a kind of semiconducter device manufacturing.

Background technology

Phosphorosilicate glass (PSG) is a kind of phosphorated silicon-dioxide.CVD prepared SiO can used ₂Mix PH in the reaction ₃Reactant gases disposes, wherein PH ₃Generate P with the oxygen reaction ₂O ₅, and be included in SiO ₂Deposit film the inside, so phosphorosilicate glass is by P ₂O ₅And SiO ₂Mixture form jointly.Phosphorus content in the PSG can be by PH ₃Flow control adjusted.PSG depositing technics commonly used now is high-density plasma chemical vapor deposition technology (HDP CVD).Because it is lower that the PSG material has a deposition temperature, and the surface of relatively flat and clearance filling capability preferably, now usually as first inter-level dielectric.At SiO ₂The middle P that adds ₂O ₅Can reduce membrane stress, and then improve the integrity of film.Phosphorus doping also can increase the water absorption resistance of glass, and the effective non diffusible ion impurity of PSG layer in addition is so phosphorosilicate glass is used to do passivation layer usually.

In general the application, the phosphorus doping density in the phosphorosilicate glass is 4-5% (weight percent).But it is very little and when not having etching barrier layer (etch stop layer) when the critical size (CD) of device, phosphorus doping density in the PSG layer is increased to about 9%, and cooperating corresponding self-aligned contact hole etching, the problem of etching stopping (being the detecting etching terminating point) can be controlled effectively.

But, carrying out in the phosphorosilicate glass preparation process with high density plasma technology, when phosphorus concentration reaches 9%, because the distinctive secondary sputter of high density plasma deposition (HDP CVD) technology, in the phosphorosilicate glass layer that covers step, form the phenomenon (flowerpattern of so-called pattern design, see Fig. 1, the step that wherein is capped is positioned at the centre of flower shape), the etching performance of phosphorosilicate glass that wherein is positioned at the etching performance of phosphorosilicate glass of " flower " and its outside is different.If, be unfavorable for the carrying out of accurate etching technology so in the phosphorosilicate glass layer of preparation " pattern design is excessive ",, then can cause the phenomenon of etching stopping because of two different etching performances in zone as the position that this pattern expands the etching contact hole to.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of preparation method of phosphorosilicate glass, and it can make the pattern design in the phosphorosilicate glass layer of preparing obviously diminish less.

For solving the problems of the technologies described above, the preparation method of phosphorosilicate glass of the present invention, adopt silane as reactant gases, the employing high density plasma deposition process is prepared, in deposition process, adopted the processing condition of the different deposit sputter of multistep ratio to carry out consecutive deposition, wherein the first step deposit is with deposit sputter bigger processing condition, adopt the smaller processing condition of deposit sputter in the follow-up depositing step, and in adjacent two depositing steps the difference of used deposit sputter ratio in 1～2.5 numerical range.

When adopting multistep successive deposit sputter than different high density plasma deposition process deposit phosphorosilicate glasses, promptly use the deposit sputter than higher technology deposit segment thickness earlier, be deposited to the thickness of requirement again with the lower processing condition of deposit sputter, then can take into account (flower pattern) size and the height problem of pattern design in the phosphorosilicate glass layer simultaneously.In above-mentioned preparation process, the adjustment of deposit sputter ratio mainly is by reactant gas silane (SiH ₄) total amount control, power and pressure can not change easily.In the first step deposit, the flow that increases silane can obviously improve deposit sputter ratio, promptly significantly increases illuviation, reducing the sputter effect relatively, in other depositing step, mainly is to reduce deposit sputter ratio by the flow that reduces silane, promptly reduce illuviation, increase the sputter effect relatively.Scanning electron microscopy (SEM) photo result shows that the present invention can significantly reduce the lateral dimension of pattern design and significantly reduce pattern design height longitudinally.

Description of drawings

The present invention is further detailed explanation below in conjunction with accompanying drawing and embodiment:

The pattern design synoptic diagram of Fig. 1 for forming in the phosphorosilicate glass deposit;

Fig. 2 is for adopting the phosphorosilicate glass layer synoptic diagram of method preparation of the present invention.

Embodiment

In carrying out the phosphorosilicate glass preparation, want the formed step of cover gate usually.In high density plasma technology, there are two kinds of phenomenons of deposit and sputter, can regulate the relative ratio (being called for short deposit sputter ratio) of deposit in the process and sputter by regulating processing condition.The present invention is divided into multistep with the deposit of phosphorosilicate glass in the high density plasma technology and carries out continuously, in the first step deposit, carry out with the processing condition that the deposit sputter is bigger, deposit sputter ratio can be controlled between 5.7～6.7, and the adjustment of deposit sputter ratio can be passed through reactant gas silane (SiH ₄) total amount control, power and pressure in the general deposit can not change easily.Increase SiH ₄Flow can obviously improve deposit sputter ratio, promptly significantly increase illuviation, reduce the sputter effect relatively.1/2～2/3 height of the grid step that need to cover is filled in the first step deposit approximately.The result shows the lateral dimension that can significantly reduce pattern design (flower pattern) like this.In follow-up depositing step, the deposit sputter is than being controlled at less than under 5.5 the processing condition.Can be by reducing SiH ₄Flow reduces deposit sputter ratio, promptly reduces illuviation, increases the sputter effect relatively.

The thickness of the number of times of remaining depositing step and each deposit is determined on a case-by-case basis, and finishes up to thickness deposit on request.The difference of the deposit sputter ratio between every adjacent twice depositing step should preferably be controlled at about 1 in 1～2.5 scope.In the processing condition of adjacent twice depositing step, the difference of deposit sputter ratio surpasses at 2.5 o'clock, has observed obvious score layer phenomenon.This several steps can significantly reduce pattern design height longitudinally.Mainly require to determine since the thickness of second other step that goes on foot according to general thickness.

Fig. 2 is for adopting the phosphorosilicate glass layer of the inventive method preparation, the transverse width of pattern design wherein and vertically highly obviously reducing.In above-mentioned all depositing steps, phosphorus concentration will be adjusted to respectively within the scope of requirement (about 9%), and the concentration difference surpasses 0.2%.The adjustment of phosphorus concentration mainly is by the phosphine gas (PH in the reactant gases ₃) the flow adjustment realize.

Claims

1, a kind of preparation method of phosphorosilicate glass, with silane as reactant gases, the employing high density plasma deposition process is prepared, it is characterized in that: in deposition process, adopted the processing condition of the different deposit sputter of multistep ratio to carry out consecutive deposition, wherein the first step deposit is with deposit sputter bigger processing condition, adopt the smaller processing condition of deposit sputter in the follow-up depositing step, and in adjacent two depositing steps the difference of used deposit sputter ratio in 1～2.5 numerical range.

2, preparation method as claimed in claim 1 is characterized in that: described the first step deposit, carry out deposit with the deposit sputter than the processing condition between 5.7～6.7; In the described follow-up depositing step, adopt the deposit sputter than carrying out deposit less than 5.5 processing condition.

3, preparation method as claimed in claim 1 or 2 is characterized in that: described different deposit sputter is than being realized by the flow of regulating silane in the deposition process.