CN100442447C

CN100442447C - Method for forming aluminum-mirror layer by back-etching and chemical mechanical grinding

Info

Publication number: CN100442447C
Application number: CNB2005100303024A
Authority: CN
Inventors: 俞昌; 杨春晓
Original assignee: Semiconductor Manufacturing International Shanghai Corp
Current assignee: Semiconductor Manufacturing International Shanghai Corp; Semiconductor Manufacturing International Beijing Corp
Priority date: 2005-09-29
Filing date: 2005-09-29
Publication date: 2008-12-10
Anticipated expiration: 2025-09-29
Also published as: CN1941291A

Abstract

The invention is concerned with the etch-back and chemistry machinery rubbing technics, which is combining the etch-back and chemistry machinery rubbing to form the aluminum mirror level. The invention can avoid the disadvantage by the following steps to be the negative influence for the product quality, such as creating the dielectric hollow, the etching spot and the atom after reactive ion etches, in order that the aluminum surface of the product is none or a few shortages. The invention can use for the micro-display, the micro electrical motor system (MEMS), and the micro optical mechanism system (MOMS) etc.

Description

With eat-backing the method that forms aluminum-mirror layer with cmp

Technical field

The present invention relates to eat-backing in the semi-conductor industry (Etch Back) and chemical mechanical milling tech, particularly a kind of usefulness is eat-back to combine with cmp and is formed the method for aluminum-mirror layer.

Background technology

In semiconductor fabrication process, conventional aluminium pattern definition all adopts reactive ion etching (RIE) to come etching aluminium, and this method is easy to make the reflectivity of aluminium to descend, and occurs oxide skin(coating) depression and residue defective in the integrated circuit patterns easily.

Forming the aluminium characteristic pattern with reactive ion etching is a kind of technology of maturation, but wherein there are many shortcomings equally, those skilled in the art should be able to understand, for example eat-backing (etch back) when removing the dielectric on aluminium surface, be easy to the serious depression (dishing) and the problem of residue occur at dielectric layer, on the aluminium minute surface, have various defectives, pitting for example, particulate etc.Concerning the semiconductor device that is used for imaging device, the common purpose of people is to form aluminium minute surface and the mutual structure in one plane of characteristic pattern.Yet owing to above-mentioned depression, residue defective reason such as particulate for example, adopt existing method in fact to be not easy to form gratifying plane, above-mentioned such as pitting (pitting), defectives such as particulate can be observed at aluminium film surface regularly, and this directly has influence on the performance of semiconductor device.

In the pattern definition of the aluminium of standard or other film, the result that some do not expect to have can take place, for example, and recessedization (dishing), film is inhomogeneous, the problem of residue and defective.Such as based on the liquid crystal device LCOS (Liquid Crystal On Silicon) of silicon, above-mentioned problem can have a negative impact to performance, reliability or the productive rate of device concerning an IC device.

With the aluminum-mirror layer step that forms LCOS for example, the step of conventional formation aluminum-mirror layer comprises the etching of aluminium, oxide deposition, and the cmp of oxide, oxide etch-back and to the finishing cmp of aluminium, these processing steps have many shortcomings:

1, film is inhomogeneous and oxide is remaining.This is because the inhomogeneities of the machine of deposited oxide itself causes, is very difficult to eliminate.To the aluminum-mirror layer of LCOS for instance, the inhomogeneous scope of the oxide thickness from the center wafer to the Waffer edge is 800～900 And this inhomogeneous oxide remnants and the raceway groove depression of can in follow-up step, causing;

2, concerning specular layer, it is supposed to have high as far as possible light reflectivity, therefore expect that the defective on the minute surface is few more good more, but can know from top introduction, after aluminium deposit processing procedure forms aluminum metal layer, also have 5 steps, each step has all increased the possibility of wafer generation defective, pitting (pitting) for example, scratch etc.

3, step in the end, in order to remove oxide residue, to aluminium modification property cmp (touch up CMP), its milling time is longer more than 3 times or 3 times than the conventional cmp time, the cmp that raise undoubtedly causes the risk of scratch, the reason that produces scratch has many kinds, for example, before to the finishing cmp of aluminium or the large particulate matter that forms in the process of this grinding steps own just can in grinding, cause scratch.Generally speaking, the time of grinding is few more, and what produce scratch may be also more little.

Summary of the invention

Dielectric depression, pitting (pitting) that the subsequent step that adopts for fear of above-mentioned reactive ion etching (RIE) back produces, shortcomings such as particulate propose the present invention to the negative effect of product quality.

Main purpose of the present invention is, provides a kind of usefulness to eat-back to combine with cmp to form the method for aluminum-mirror layer, and this method can avoid bringing various shortcoming mentioned above, and the aluminium surface of product is not had or the described defective of considerably less appearance.The present invention can be applicable to various purposes, for example little (Micro-Display), microelectromechanical-systems (MEMS), Micro-Opto-Electro-Mechanical Systems (MOMS) of showing.

The semi-conducting material initial configuration that need handle according to the inventive method is that the superiors are dielectric membranous layers, for example silicon dioxide layer; Be the metal aluminium lamination below the dielectric layer, the metallic aluminium layer thickness is 5000 Below the middle breach of filling with dielectric that exists, metal aluminium lamination is dielectric layer.

The method according to this invention, comprising two etchback step:

The first step is to dielectric selective etch step, in this step to aluminium and dielectric etch-rate than preferably be controlled at＜1: 100, through after this step, the whole etched removals of the dielectric layer of semiconductor material surface, and the dielectric in the metallic aluminium lamellar spacing is removed certain thickness equally, and the etching of metal aluminium lamination can be ignored substantially;

Second step was the metallic aluminium etching step, this step to aluminium and dielectric etch-rate than preferably be controlled at＞100: 1.It should be noted that through eat-backing for the second time the etched certain thickness of metal aluminium lamination meanwhile, also has been removed attached to the defective on aluminium surface.In addition, because the etch-rate in place, pitting place is less than the etch-rate on aluminium surface, the pitting on aluminium surface also is removed.The dielectric that another result that aluminium is eat-back is in the hole and is filled protrudes in the aluminium lamination surface.

Through after above-mentioned two etchback step, to the semiconductor material surface modification property cmp (touch up CMP) that obtains, form metallic aluminium and the structure of dielectric attribute pattern on a copline, this kind method is aluminum chemistry mechanical lapping (CMP) method of optimizing, be embedded in aluminium feature in the dielectric layer in order to polishing, thereby can solve aforesaid various defect problem.

Generally, the step of the method for the invention is as follows:

(1) dielectric in the semi-conducting material of aluminium and dielectric substance formation is carried out selective etch, aluminium and dielectric etch-rate are than＜1: 100;

(2) aluminium in the above-mentioned semi-conducting material is carried out selective etch, aluminium and dielectric etch-rate＞100: 1;

(3) the semiconductor material surface modification property cmp to obtaining.

The invention has the advantages that, utilize method provided by the invention, can obtain the mutual structure in one plane of extraordinary formation aluminium minute surface and characteristic pattern, not have oxide situation remaining and depression and occur, not have or the considerably less aluminium lamination blemish that occurs.

Description of drawings

The accompanying drawing that comprises among the application is a component part of specification, and accompanying drawing and specification and claims one are used from explanation flesh and blood of the present invention, are used for understanding better the present invention.In the accompanying drawing, numeral 1 expression dielectric substance, numeral 2 expression metallic aluminum materials:

Fig. 1 is the schematic diagram that the inventive method is eat-back for the first time;

Fig. 2 is the schematic diagram that the inventive method is eat-back for the second time;

Fig. 3 is the schematic diagram that the aluminium surface is carried out cmp; With

Fig. 4 is the effect schematic diagram after handling by the inventive method.

Embodiment

In order to understand technology of the present invention better, the invention will be further described below in conjunction with drawings and Examples, but these embodiment are not construed as limiting the present invention.

The initial semiconductor material structures that need handle according to the inventive method as shown in Figure 1, the superiors are dielectric oxide rete, for example silicon dioxide layer; Be the metal aluminium lamination below the silicon dioxide layer, the metallic aluminium layer thickness is 5000

Below the middle breach of filling with dielectric oxide that exists, metal aluminium lamination is oxide skin(coating).

Earlier silicon dioxide layer is carried out selective etch, require etch-rate ratio to aluminium and silicon dioxide be controlled at＜1: 100, described in the present embodiment etching adopts hydrofluoric acid to carry out, and adds ammonium fluoride and controls etch-rate as buffer.Particularly, should be according to etched subject material decision etching means, for example, the etching of monocrystalline silicon and polysilicon normally utilizes the mixed liquor of nitric acid and hydrofluoric acid to carry out, the etching of silicon dioxide adopts hydrofluoric acid solution to be carried out usually, and silicon nitride can utilize the phosphoric acid solution (85%) that is heated to 180 ℃ to carry out etching.Material structure after the etching as shown in Figure 2, since the etch-rate ratio of aluminium and oxide silicon dioxide is controlled at＜1: 100, the etch-rate of silicon dioxide layer is far above the etch-rate of metal aluminium lamination, the oxide skin(coating) on last surface is all removed, and the oxide in the metallic aluminium lamellar spacing is removed certain thickness equally, and the etching of metal aluminium lamination can be ignored substantially, still 5000

About.

Then the metal aluminium lamination is carried out selective etch, require the etch-rate ratio of aluminium and silicon dioxide to be controlled at＞100: 1, described in the present embodiment etching adopts the mixed solution of phosphoric acid, nitric acid, acetic acid and water to be carried out, and ratio is 80% phosphoric acid, 5% nitric acid, 5% acetic acid and 10% water.Particularly, above-mentioned etching solution should be according to real material characteristics selection component and ratio.The material structure that obtains after the etching as shown in Figure 3 since the etch-rate ratio of aluminium and silicon dioxide be controlled at＞100: 1, the etch-rate of metal aluminium lamination is far above the etch-rate of silicon dioxide layer, last metallic aluminium layer thickness is etched to 3000

And the etch-rate of the earth silicon material in the gap of metal aluminium lamination can be ignored substantially, forms the shape that earth silicon material in the gap protrudes in aluminium surface certain distance at last.

At last to aluminium surface modification property cmp (touch up CMP), to form metallic aluminium and the structure of silicon dioxide features pattern on a copline, as shown in Figure 4, through described modification cmp, the silicon dioxide layer that protrudes in aluminium lamination is milled to and the metallic aluminium copline.

The aluminium minute surface that forms with said method does not have the situation of oxide remnants, recessedization to occur, and does not have or almost do not have defective to exist on the aluminium surface.

More than show and described basic principle of the present invention and principal character and advantage of the present invention.The technical staff of the industry should understand; the present invention is not restricted to the described embodiments; that describes in the foregoing description and the specification just illustrates principle of the present invention; the present invention also has various changes and modifications without departing from the spirit and scope of the present invention, and these changes and improvements all fall in the claimed scope of the present invention.The scope of protection of present invention is defined by appending claims and equivalent thereof.

Claims

1, a kind of usefulness is eat-back the method that forms aluminum-mirror layer with cmp, it is characterized in that comprising the steps:

(1) dielectric in the semi-conducting material of metallic aluminium and dielectric formation is carried out selective etch, wherein dielectric etch-rate is higher than the etch-rate of metallic aluminium, described dielectric layer is positioned on the metal aluminium lamination, has the breach of filling with this dielectric in the middle of this metal aluminium lamination;

Wherein aluminium and dielectric etch-rate are than＜1: 100;

(2) aluminium in the above-mentioned semi-conducting material is carried out selective etch, wherein the etch-rate of metallic aluminium is higher than dielectric etch-rate;

Wherein aluminium and dielectric etch-rate are than＞100: 1;

(3) the semiconductor material surface modification property cmp to obtaining.

2, the method for claim 1, wherein dielectric is a silicon dioxide described in the step (1), the etching solution that selective etch described in the step (1) adopts is a hydrofluoric acid solution.

3, the method for claim 1, wherein dielectric is monocrystalline silicon or polysilicon described in the step (1), the etching solution that selective etch described in the step (1) adopts is the mixed liquor of nitric acid and hydrofluoric acid.

4, the method for claim 1, wherein dielectric is a silicon nitride described in the step (1), the etching solution that selective etch described in the step (1) adopts is 180 ℃ phosphoric acid 85% solution.

5, the method for claim 1, wherein the etching solution that selective etch adopts in the step (2) is the mixed solution of phosphoric acid, nitric acid, acetic acid and water.