CN102655093B

CN102655093B - Realizing method of thick insulating film process

Info

Publication number: CN102655093B
Application number: CN201110049404.6A
Authority: CN
Inventors: 王海军; 孙勤
Original assignee: Shanghai Huahong Grace Semiconductor Manufacturing Corp
Current assignee: Shanghai Huahong Grace Semiconductor Manufacturing Corp
Priority date: 2011-03-02
Filing date: 2011-03-02
Publication date: 2014-12-10
Anticipated expiration: 2031-03-02
Also published as: CN102655093A

Abstract

The invention discloses a realizing method of a thick insulating film process, comprising the following steps of: (1) firstly, etching a groove at a place where a insulating dielectric film is formed; (2) oxidizing a furnace tube in the groove according to different groove widths; (3) after oxidization, growing an insulating film with better hole filling property; (4) chemically and mechanically polishing bulges on the surface to be flush; and (5) etching the insulating film in an active region, and only remaining a thick field oxide insulating film. Through changing the appearance of the etched groove, the stress direction is changed after a silicon dioxide insulating film between element bags grows in the furnace tube, the curvature radius of the measured insulating film is basically consistent with that of the insulating film before growing in the furnace tube, and therefore, the realizing method is a feasible method for solving an insulating layer with the thickness larger than 2 micrometers between the element bags.

Description

The process implementation method of thick insulating film

Technical field

The present invention relates to the dielectric film process implementation method in a kind of semiconductor device, particularly relate to a kind of process implementation method of thick insulating film.

Background technology

LDMOS (Laterally Diffused Metal Oxide Semiconductor, Laterally Diffused Metal Oxide Semiconductor) is one of conventional device in current RF (Radio Frequency) radio frequency process.Based on LDMOS, can form low cost, the RFLDMOS of high-performance high integration is applied to HF communication field and other are for the very high application of rate request.The growth extension of common RFLDMOS structure as shown in Figure 1.In order to improve the cut-off frequency of device, need to reduce the electric capacity of isolated insulation layer between unit's bag, increase the thickness of insulating barrier, at present feasible field oxygen isolation or high-density plasma deielectric-coating are grown up and are added the way of cmp again, can only accomplish 2 microns of left and right.

Meanwhile, in realizing the technical process of thick insulating film, because thick oxide film is high temperature furnace pipe borough chief, after cooling because the stress under compression of silicon and the stress under compression of silicon dioxide seriously do not mate, cause seriously projection of wafer, can not be held by mechanical hand, can not enter down technique one.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of process implementation method of new thick insulating film, has solved the real feasible solution that thickness between first bag is greater than 2 microns of insulating barriers.

For solving the problems of the technologies described above, the process implementation method of thick insulating film of the present invention, comprises step:

(1) at place that need to long dielectric insulating film, first etching groove;

Wherein, the width of groove is 0.2～1 micron, and the degree of depth is 1～20 micron; The pattern of groove is oblique shape (as trapezoidal shape), and angle is less than or equal to 89 degree angles, preferably 88 degree angles;

The concrete grammar of described etching groove comprises:

A, at the surface-coated photoresist of silicon chip silicon dioxide, define the groove of required etching, wherein, the thickness of photoresist is greater than 0.5 micron;

After B, photoresist exposure, at silicon chip epitaxial part, define the position of the groove of the etching of wanting;

C, by dry plasma, obtain needed groove;

(2), in groove, according to different groove widths, carry out furnace oxidation;

Wherein, the thickness of oxidation is between 0.4 micron～2 microns; The temperature of oxidation is 850～1250 ℃, and the time of oxidation is greater than 30 minutes;

(3) after oxidation, the good dielectric film of growth filling perforation;

Wherein, the mode of growth can be to grow up in boiler tube in the mode of wet oxygen;

Described dielectric film can be the dense dielectric film (as silicon dioxide) that boiler tube is grown up, or sub-normal pressure chemical gas phase film forming;

(4) cmp, polishes surperficial projection;

(5) again the dielectric film of active area is etched away, only leave thick field oxygen dielectric film; Wherein, dielectric film lithographic method can be dry plasma; The thickness of this oxygen dielectric film is greater than 2 microns, thereby meets the requirement that reduces electric capacity and improve operating frequency.

In insulating barrier distribution density, be greater than 5% when above, during through boiler tube growth insulating oxide, the stress between silicon substrate and oxide-film does not seriously mate, and wafer there will be serious warpage after having grown dielectric oxide film, can not carry out technique below.And utilizing method of the present invention, the stress well having solved between silicon substrate and oxide-film does not mate, and makes product can continue technique below.The stress after boiler tube borough chief oxide-film while focusing on etching deep trouth because of the present invention, the pattern of groove is carved into oblique shape (angle is less than or equal to 89 degree), so just can be offset a part.

Therefore, the present invention is by changing after the pattern of etching groove, after silica insulation film between unit's bag is grown up in boiler tube, changed the direction of stress, after measuring, radius of curvature and the radius of curvature entered before the long film of boiler tube are basically identical, have solved the feasible solution that thickness between first bag is greater than 2 microns of insulating barriers.In addition, owing to having formed thicker field oxygen dielectric film, therefore, can improve RF LDMOS operating frequency.

Accompanying drawing explanation

Below in conjunction with accompanying drawing and embodiment, the present invention is further detailed explanation:

Fig. 1 is the growth extension schematic diagram of common RFLDMOS structure;

Fig. 2 is the design diagram in photoresist definition deep trouth district;

After Fig. 3 is photoresist exposure, the position view of etching groove is wanted in definition;

Fig. 4 is the schematic diagram that etches down the groove of oblique looks;

Fig. 5 is the schematic diagram after high temperature furnace pipe range silicon dioxide;

Fig. 6 is the actual silicon chip figure that forms thick field oxygen dielectric film.

Embodiment

The process implementation method of thick insulating film of the present invention, comprises step:

(1) in place that need to long dielectric insulating film, first etching groove, concrete steps comprise:

A, the photoresist that is greater than 0.5 micron at the surface-coated thickness of silicon chip silicon dioxide, define the groove of required etching, as shown in Figure 2;

After B, photoresist exposure, at silicon chip epitaxial part, define the position of the groove of the etching of wanting, as shown in Figure 3;

C, by conventional dry plasma, obtain down the tiltedly groove of shape (angle is less than or equal to 89 degree angles), wherein, the width of groove is 0.2～1 micron, the degree of depth is 1～20 micron, result as shown in Figure 4;

(2) in groove, according to different groove widths, carry out furnace oxidation, the temperature of oxidation is 850～1250 ℃, and the time of oxidation is greater than 30 minutes, and the thickness of oxidation is between 0.4 micron～2 microns;

(3) after oxidation, with the mode of the wet oxygen good dielectric film silicon dioxide of filling perforation of growing up in boiler tube;

(4) cmp, polishes surperficial projection, and result as shown in Figure 5;

(5) again the dielectric film of active area after chemical liquid is with conventional dry plasma, only leave the field oxygen dielectric film that thickness is greater than 2 microns.

The actual silicon chip finally obtaining according to above-mentioned steps, after the test of radius of curvature tester, result as shown in Figure 6, from this figure it is clear that, has formed the field oxygen dielectric film that thickness is greater than 2 microns between unit's bag.

In addition, measure the silicon chip radius of curvature after growing up enter the silicon chip radius of curvature before the long film of boiler tube with in boiler tube, result is as shown in table 1, from this table, can obviously find out, enter the radius of curvature before the long film of boiler tube and in boiler tube the radius of curvature after growth basically identical, therefore, the present invention can solve thickness between unit's bag and be greater than the problem of 2 microns of insulating barriers, and by forming thick field oxygen dielectric film, can improve RF LDMOS operating frequency.

The radius of curvature comparison sheet of table 1 different process

Note: 8000A (8000 dust) is the thickness of film

Claims

1. a process implementation method for thick insulating film, comprises step:

(1) in place that need to long dielectric insulating film, first etching groove, the width of groove is 0.2～1 micron, and the degree of depth is 1～20 micron, and the pattern of groove is oblique shape, and angle is less than or equal to 89 degree angles;

(2) in groove, according to different groove widths, carry out furnace oxidation, the thickness of oxidation is between 0.4 micron～2 microns, and the temperature of oxidation is 850～1250 ℃, and the time of oxidation is greater than 30 minutes;

(3) after oxidation, the good dielectric film of growth filling perforation;

(4) cmp, polishes surperficial projection;

(5) dielectric film of active area is etched away again, only leave thick field oxygen dielectric film, the thickness of an oxygen dielectric film is greater than 2 microns.

2. the process implementation method of thick insulating film as claimed in claim 1, is characterized in that: the angle ranging from 88 degree angles.

3. the process implementation method of thick insulating film as claimed in claim 1, is characterized in that: in described step (1), the method for etching groove comprises:

A, at the surface-coated photoresist of silicon chip silicon dioxide, define the groove of required etching, the thickness of photoresist is greater than 0.5 micron;

C, by dry plasma, obtain needed groove.

4. the process implementation method of thick insulating film as claimed in claim 1, is characterized in that: in described step (3), with the mode of the wet oxygen good dielectric film of filling perforation of growing up in boiler tube.

5. the process implementation method of thick insulating film as claimed in claim 4, is characterized in that: described dielectric film is dense dielectric film or the sub-normal pressure chemical gas phase film forming that boiler tube is grown up.

6. the process implementation method of thick insulating film as claimed in claim 1, is characterized in that: in described step (5), dielectric film lithographic method is dry plasma.