CN1103493C

CN1103493C - Method of reducing the micro load produced during nitride etching

Info

Publication number: CN1103493C
Application number: CN 98119218
Authority: CN
Inventors: 朱新萍
Original assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
Current assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
Priority date: 1998-06-18
Filing date: 1998-09-09
Publication date: 2003-03-19
Anticipated expiration: 2018-09-09
Also published as: CN1239818A; TW376553B

Abstract

The present invention relates to a method for reducing micro-loads generated in an opening contour when a nitride layer is etched, which comprises the following steps: firstly, a substrate on which a nitride layer is formed is provided; secondly, a photoresist layer is formed on the nitride layer, and is exposed and developed by limited patterns. In a reactive ion etching reactor, oxygen and argon are used as plasma gas so as to pretreat the photoresist layer bu plasmas so that the photoresist layer is reduced. The nitride layer is etched by using the photoresist layer as a mask. The present invention pretreats the photoresist layer by the plasmas so as to reduce a micro-load effect.

Description

Produce the method for micro-loading when being reduced in nitride etching

Technical field

The present invention relates to a kind of nitride (nitride) layer etching method, and particularly relate to a kind of method that produces micro-loading (micro-loading) when being reduced in the nitride etching layer at opening profile (profile).

Background technology

In semiconductor fabrication process, regular meeting uses the step of nitride etching layer.In existing technology, when the nitride etching layer, can produce the phenomenon of micro-loading at the opening profile.So-called micro loading effect is meant that nitride layer is after etching, the sidewall (sidewall) of (dense area) and two formed openings of zones of different of low-density pattern area (openarea) (opening) in the high density patterns district, the different phenomenon of its slope (slope).

Please refer to Fig. 1, what it illustrated is the generalized section of existing nitride etching layer method.One substrate (substrate) 100 at first is provided, in substrate 100, forms mononitride layer 102.Secondly, on nitride layer 102, form a photoresist layer 104.Through after the etching, the opening 106 sidewall slopes in high density patterns district can be littler than the opening 108 sidewall slopes of low-density pattern area, and this is the micro-loading phenomenon.With regard to scale size, in the high density patterns district, the width of photoresist layer 104 represents that with a the width of nitride layer 102 is represented with b; In the low-density pattern area, the width of photoresist layer 104 is with a ' expression, and the width of nitride layer 102 is with b ' expression; Opening 108 bottom widths in the low-density pattern area are represented with d.Nitride silicon nitride (Si for example wherein ₃N ₄).When a=a ' time, (b-b ') promptly is so-called micro loading effect.The A/F that this micro loading effect can make the opening 108 bottom width d of low Mi Dituanqu become and be limited than photoresist layer 104 is also narrow.

This micro-loading phenomenon can make follow-up element manufacturing produce defective or failure.Critical dimension in manufacture craft (critical dimension) reduces day by day, for example in the step that forms self-aligned contacts window (selfaligned contact) and fleet plough groove isolation structure (shallow trench isolation), the influence of micro loading effect is even more serious.

Summary of the invention

Therefore main purpose of the present invention just provides a kind of method that produces micro-loading when being reduced in the nitride etching layer at the opening profile.

For achieving the above object, the method that produces micro-loading when being reduced in nitride etching of the present invention may further comprise the steps: a substrate at first is provided, and forms the mononitride layer in substrate.Secondly, on nitride layer, form a photoresist layer, utilize a pattern that has limited, the photoresist layer is carried out exposure imaging, then in reactive ion etching reactor (reactive ion etching chamber), with oxygen and argon plasma gas, the photoresist layer is carried out plasma preliminary treatment (descumming) step, make the photoresist layer reduce.Be mask (mask) with the photoresist layer then, nitride layer is carried out etching, produce to reduce micro loading effect.

Brief description of drawings

For above-mentioned and other purposes of the present invention, feature and advantage can be become apparent, a preferred embodiment cited below particularly, and conjunction with figs. elaborates.In the accompanying drawing:

It is illustrated Fig. 1 is the generalized section of a kind of nitride etching layer method of prior art;

What Fig. 2 illustrated is the generalized section that has a mononitride layer and a photoresist layer in a substrate;

What Fig. 3 illustrated is the generalized section that has the photoresist layer of a mononitride layer and a process development in a substrate;

What Fig. 4 illustrated is to have the photoresist layer of mononitride layer and through developing in a substrate, passes through plasma pretreatment step generalized section afterwards again;

What Fig. 5 illustrated is to have the photoresist layer of mononitride layer and through developing, the generalized section after plasma pretreatment step and nitride etching layer in a substrate.

Detailed description of the preferred embodiment

Please refer to Fig. 2, a substrate 200 at first is provided, in this substrate 200, form mononitride layer 202.The substrate 200 of indication herein comprises that the semiconductor-based end and other can be used as the ground of nitride layer 202, as interlayer dielectric material (interlayer Dielectric), metal intermetallic dielectric layer (intermetaldielectric).In addition, nitride layer 202 can deposit with general Low Pressure Chemical Vapor Deposition (LPCVD), its material such as silicon nitride (Si ₃N ₄).

Secondly on nitride layer 202, form a photoresist layer 204.Again with one limiting pattern this photoresist layer 204 is carried out exposure imaging, the mask with as nitride etching layer 202 time.

Then please refer to Fig. 3, photoresist layer 204 presents the pattern that has limited in advance after developing.Wherein limiting pattern is not limited to the pattern shown in the figure.For a preferred embodiment of the present invention is described, the pattern that has limited among the figure has comprised the high density patterns district in figure left side and the low-density pattern area on figure right side.

In the prior art, photoresist layer 204 can produce residue through after developing, and in plasma etch reactor, is plasma gas with oxygen then, carries out the plasma pretreatment step and removes residue.Because this plasma pre-treatment step is each homogeny (isotroic), so the size of photoresist layer 204 top and sidewall width can be done forr a short time.The present invention utilizes this proper noun of plasma pretreatment to describe the reduction action of in the present invention photoresist layer 204 being done, and the method for its use and step are different fully with existing plasma pretreatment.

Plasma pretreatment of the present invention and its difference of existing plasma pretreatment are the mists with oxygen and argon gas, or with the mist of oxygen and nitrogen as plasma gas.And when carrying out plasma pretreatment, on the power supply unit of reactive ion etching reactor, apply a bias voltage (power bias).Wherein the reactive ion etching device is preferably APPLIED MATERIALS P-5000MXP.

Wafer used in the manufacture craft is placed the reactive ion etching reactor bottom, and apply an AC grid bias power supply (bias power) at the reactive ion etching reactor bottom, the concentration that then is attracted to the cation of wafer surface can become higher.So in the plasma pretreatment process, near wafer surface, have more cation, thereby make photoresist layer 204 width reduction.Reduction in the low-density pattern area is more remarkable than the low-density pattern area.Reduction also can be subjected to the influence of the mixed proportion of oxygen/argon in the mist plasma or oxygen/nitrogen in addition.When the gas mixture ratio example increased in the plasma, the variation of reduction also and then increased.When reactor ionic medium gas pressure and grid bias power supply increase, the variation of reduction also increases thereupon.

APPLIED MATERIALS P-5000 MXP reactive ion etching device is equipped with a main input power supply, in the plasma pretreatment process, use bias voltage input power supply (power bias input), can be so that the reduction higher density pattern area of low-density pattern area be bigger, therefore available this method is improved the problem of micro-loading.Because photoresist layer 204 is bigger in the reduction of low-density pattern area, the slope of its sidewall becomes less, so when carrying out follow-up manufacture craft, the opening size of the nitride layer 202 of photoresist layer 204 below has more correct size.

In the plasma pretreatment process, accurately control aforementioned affect plasma pretreatment variable quantity, just can control the size of reduction, and can improve the micro-loading phenomenon.

Please refer to Fig. 4, after the plasma pretreatment step, photoresist floor 204 can be greater than the reduction in high density patterns district in the reduction of low Mi Dituanqu.Therefore photoresist layer 204 width in the low-density pattern area are e ', rather than the previous formed width e of plasma pretreatment.

Secondly, please refer to Fig. 5, through after the etching, the micron load effect can occur in the nitride layer 202 of low Mi Dituanqu.With Fig. 1 more as can be known, behind plasma pretreatment step and etching step, the width e of the photoresist layer 204 of low-density pattern area ' can diminish with the width f of nitride layer 202 makes that the width w ' of nitride layer 202 split sheds 208 is identical or close with the A/F w that pattern desire that previous utilization has limited forms.So the A/F w ' among Fig. 5 is identical or close with A/F w among Fig. 3.

When using APLIED MATERALS P-5000 MXP reactive ion etching device to carry out the plasma pretreatment step, the scope that influences each variable quantity of plasma pretreatment is as follows: plasma gas pressure is 50 to 100 milli torrs (millitorr), bias voltage input power supply is 150 to 250 watts, the mixed proportion of oxygen/argon is 1: 8 to 1: 5, and the time of plasma pretreatment step was at least 15 seconds.At plasma gas pressure is 50 milli torrs, bias voltage input power supply is 250 watts, the gas flow of oxygen is 15sccm (Standard Cubic Centimeter Per Minute) in the plasma gas, the gas flow of argon gas is 75sccm, the time of plasma pretreatment step is 30 seconds, can obtain preferred effect.

Influence about plasma gas pressure, can be when pressure is low so that photoresist layer reduction uniformity is better, but when plasma gas pressure is too low, can cause harmful effect to the nitride layer under it, therefore comparatively ideal plasma gas pressure limit is at 50 to 100 milli torrs.

In the conventional method, only use oxygen to be plasma gas, carry out plasma pretreatment.And in the present invention, then being to use oxygen and argon gas is plasma gas.When carrying out plasma pretreatment, can make the low-density pattern area different with the photoresist floor reduction in high density patterns district.

Though the present invention discloses as above in conjunction with a preferred embodiment; but it is not in order to limit the present invention; those skilled in the art can make various changes and retouching without departing from the spirit and scope of the present invention, so protection scope of the present invention should be defined by accompanying Claim.

Claims

1. a method that produces micro-loading when being reduced in nitride etching comprises the following steps:

One substrate is provided;

In this substrate, deposition mononitride layer;

On this nitride layer, deposit a photoresist layer;

Utilize a pattern that has limited, this photoresist layer is exposed and develops;

Carry out a plasma preliminary treatment, in a reactive ion etching reactor, as plasma gas, this photoresist layer is carried out plasma pretreatment, make this photoresist layer produce reduction with oxygen and argon gas; And

With this photoresist layer is a mask, and this nitride layer is carried out etching.

2. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 1, wherein this reactive ion etching reactor assembly comprises bias voltage input supply unit.

3. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 1, wherein the argon gas in the employed plasma gas of this device replaces with nitrogen.

4. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 3, wherein this plasma pretreatment unit comprises bias voltage input supply unit.

5. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 1, wherein the oxygen/argon mixed proportion in the employed plasma gas of this device is 1: 8 to 1: 5.

6. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 2, wherein the bias voltage of this device input power supply is 150 to 250 watts.

7. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 2, wherein the oxygen/argon mixed proportion in the plasma gas that this device used is 1: 8 to 1: 5.

8. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 3, wherein the bias voltage of this device input power supply is 150 to 250 watts.

9. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 3, wherein the oxygen/argon mixed proportion in the employed plasma gas of this device is 1: 8 to 1: 5.

10. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 5, wherein the pretreated time of this plasma is 15 seconds at least.

11. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 5, wherein the gas pressure of this plasma is 50 to 100 milli torrs.

12. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 10, wherein this wherein the gas pressure of this plasma be 50 to 100 milli torrs.

13. the method that produces micro-loading when being reduced in nitride etching as claimed in claim 10, wherein the argon gas in this plasma gas replaces with nitrogen.