CN207367927U - A kind of equipment for improving wafer inner film thickness uniformity - Google Patents

Abstract

The utility model discloses a kind of equipment for improving wafer inner film thickness uniformity.This equipment is to be used for IC Chip Production.This equipment is by the way that wafer is placed upward, chemical abrasive material is flowed into crystal column surface, with the grinding head that posts grinding pad of one or more diameters between 10~40 millimeters selective differentiation grinding is carried out in crystal column surface, differentiation grinding is to be divided into several sections by the route for passing through grinding head, and realized in different sections using different pressures and sweep speed, the size in the number in section and each section is that the actual distribution of thickness in the wafer measured according to before processing determines.Wafer inner film thickness uniformity can so be greatly improved, so as to meet increasingly harsh technological requirement.

Description

A kind of equipment for improving wafer inner film thickness uniformity

Technical field

The utility model is a kind of equipment for improving the wafer inner film thickness uniformity of IC Chip Production.

Background technology

IC Chip Production is that the film of multiple layers of different materials is equipped with by micrographics technology formation transistor device Superposition, wherein insulating materials are as layer is electrically isolated, and metal material is as conducting line.Multilayer interconnection can be greatly enhanced core For piece integrated level so as to reduce the size of chip, chemical mechanical grinding is exactly to realize the critical process of multilayer interconnection.Chemical machinery is ground The purpose of grinding process is so to avoid surface planarisation caused by uneven before next layer of line is superimposed Line fractures.Chemical mechanical milling tech is used, in such as less than 28 nanometers of advanced technology nodes, the number of plies for connecting up superposition can be with Accomplish more than ten layers.

Chemical mechanical grinding is realized by chemical-mechanical grinding device, and Fig. 1 illustrates typical chemical mechanical grinding The composition of equipment.When grinding starts, it is loaded in as the wafer 1 of chip carrier in grinding head 2, face down is pressed in grinding pad On 3,3 rotation in the same direction of grinding head 2 and grinding pad, while there is chemical abrasive material 4 to drop on grinding pad 3 and flow to 1 table of wafer by rotation Face is so as to complete chemical mechanical grinding.As its name suggests, the existing chemical grinding of chemical mechanical grinding (passing through chemical abrasive material 4), also has Mechanical lapping (passes through the rotation of grinding head 2 and grinding pad 3).

Grinding pad 3 is made of chemical synthetic material, on the grinding table 5 of hard stainless steel material.Grinding There are the groove of regular figure and trickle pore on pad 3, chemical abrasive material 4 can be allowed to be transmitted and absorb the chemical abrasive material of holding 4.Grinding pad 3 is typically much deeper than the size of grinding head 2., can be with substantial amounts of deionized water 6 come cleaning grinding pad 3 after grinding.

Chemical abrasive material 4 is usually by tens to hundreds of nanometers of grain dissolution in the chemical reagent for having certain acid-base value. Grain can be silica, iron oxide etc., and the chemical abrasive material 4 for metal film grinding can also add certain proportion hydrogen peroxide to help Help oxidized metal.In addition a variety of micro medicaments can add, such as surfactant, anti-freezing mixture etc., come enhancing Learn the reactivity and stability of abrasive material 4.

Correction-plate 7 is new for grinding pad 3 scrape after grinding, removes the weathered fiber group in surface Knit, expose following fresh part, so as to keep grinding rate.Correction-plate 7 is typically to be bonded by small artificial diamond granule On metal dish.

Grinding head 2 is the carrier of transmission and grinding crystal wafer 1, its size is more bigger than wafer 1.Before starting grinding, grind Bistrique 2, which plays 1 vacuum suction of wafer, moves again to the top of grinding pad 3.Then grinding head 2 drops on grinding pad 3.Fig. 2 is shown The construction of one subregion grinding head 2 and its control the principles of wafer 1 surface film thicknesses.Grinding head 2 passes through interior at 1 back side of wafer The inflation of air bag 89 put applies pressure, and starts simultaneously at rotation.After grinding, 2 vacuum suction of grinding head plays wafer 1 and transmits it Go to clean.Wafer 1 skids off in high-speed rotating grinding head 2 in order to prevent, and retaining ring 10 is housed in the periphery of grinding head 2.Protect Held in ring 10 is typically to be bonded in by the ring of a synthetic plastic material on stainless steel coil, and stainless steel coil is installed on grinding by screw On first 2.There is groove on 10 surface of retaining ring, is to allow chemical abrasive material 4 to enter by retaining ring 10 wafer 1 under grinding head 2 Surface.

The purpose of chemical mechanical grinding is planarization, so the uniformity of 1 inner film thickness of wafer is crucial finger after grinding Mark.With the increase (from 300 millimeters of 150 millimeters of mainstreams till now) of 1 size of wafer, the size of grinding head 2 is also increasing.Such as Shown in Fig. 2, since the 1 outermost linear velocity of wafer in grinding head 2 is more than the linear velocity at center, and 1 outermost of wafer Contact chemical abrasive material 4 in portion's is more prone to, so inside the wafer 1 in grinding head 2, outermost grinding rate is higher than naturally The grinding rate at center.Therefore, multiple annular isolation air bags 8 (most middle is circular) are employed in grinding head 2, by gas Capsule 8 is subject to different air pressures, and air pressure is bigger, and grinding rate is higher, so as to reach the speed that can adjust different zones respectively Purpose.Show that is divided into a trizonal grinding head 2 in Fig. 2, the region 11 at center is circle, and other two regions 12,13 be annular.If some region of amount of grinding needs to increase, just the pressure of the air bag 8 of respective regions is increased.With crystalline substance Circle 1 and the size of grinding head 2 are continuously increased, and the number of air bag 8 is also continuously increased, from scratch, from two to five, then to seven It is a.The construction of such grinding head 2 becomes increasingly complex, and cost is higher and higher, safeguards and installation is also more and more difficult.But even if not Disconnected to increase 8 number of air bag, the uniformity of 1 inner film thickness of wafer still cannot meet increasingly harsh requirement after grinding.Such as two A 8 intersection of air bag is influenced while can be subject to two adjacent region different pressures.Furthermore to occurring in same 8 region of air bag It is in uneven thickness the problem of, only increase by 8 number of air bag one region is subdivided into multiple regions.But 8 number of air bag It can not possibly continue to increase, this is because the wafer 1 of hard but fragile crisp silicon materials can not possibly be the two of adjacent very little Bent and come so as to all be in close contact with the two regions and receive different pressures in a region.

Grinding terminates, and 1 surface adhesion of wafer has the particle of substantial amounts of chemical abrasive material 4, to must be complete before next step process Portion is cleaned.So chemical-mechanical grinding device carries the wash equipment of oneself.Use to hairbrush and chemistry and try in cleaning The consumptive materials such as agent, last wafer 1 can be dried.

Grinding pad 3, correction-plate 7, the retaining ring 10 and 8 film of air bag of grinding head 2 have certain service life, and the time limit reaches To being replaced afterwards with regard to needs, so they are all consumptive materials.Chemical abrasive material 4 is also a kind of consumptive material, it is discharged using rear, no It can be recovered and reuse.So chemical mechanical grinding uses substantial amounts of consumptive material, cost is very high.

The utility model is thickness in wafer 1 after to IC Chip Production technique such as chemical mechanical grinding Degree uniformity is significantly improved, so as to meet increasingly harsh, but 1 inner membrance of wafer that multi partition grinding head 2 is unable to reach Thickness evenness requirement.In addition the utility model can draw last full stop to the increasingly complication of grinding head 2, so as to reduce chemistry The cost of mechanical grinding device manufacture.

The content of the invention

In order to significantly improve the film thickness in the wafer 1 after IC Chip Production technique such as chemical mechanical grinding Uniformity, reaching the rigors of advanced technology nodes, (for example 300 millimeters of 1 inner film thickness maximums of wafer are to minimum value Scope is less than 30 angstroms), the utility model provides a kind of mode to be ground to IC Chip Production technique such as chemical machinery 1 inner film thickness of wafer distribution after mill is modified, so that the film thickness uniformity in wafer 1 be greatly improved.

Technical solution is used by the utility model：As shown by Fig. 3 (top is side view, and lower part is top view) , 300 millimeters of wafer 1 of the such as chemical mechanical grinding for having already passed through back process is face-up placed on and is held Hold and rotate by vacuum on microscope carrier 14, while with size between 10~40 millimeters, the grinding head of grinding pad 3 is posted on surface 2 move on 1 surface of wafer, carry out selective differentiation grinding (【014】Can illustrate), chemistry in process of lapping Abrasive material 4 can be flowed on 1 surface of wafer.After grinding, the position where grinding head 2 can first move to correction-plate 7 carries out grinding pad 3 Scrape newly, can move on to afterwards after the sink equipped with hairbrush 15 is scrubbed and stay in there until grinding next time starts.Grinding After first 2 leave wafer 1, it is equipped with the cleaning brush 16 of polyvinyl chloride synthetic material and can moves on to crystal column surface and wiped and tied back and forth Close chemical reagent 17 and deionized water 6 cleans wafer 1.After cleaning, wafer 1 can be rotated at a high speed, with reference to table Face is sprayed with room temperature or the nitrogen 18 of high temperature is dried.Blooming measuring instrument 19 can be installed in the top of wafer 1, to grinding In or grinding after thickness can be measured in real time.

So-called selective differentiation grinding, is exactly the distribution situation according to film thickness, opposite in the region of film thickness thickness The grinding that the time is longer but pressure is identical, or the grinding that the time is identical but pressure is larger are carried out in the region of thin film thickness, or Time is longer while pressure also larger grinding.Because pressure is bigger, amount of grinding can increase in same time；Equally, the time Longer, amount of grinding can also increase in the case of uniform pressure.Milling time is the speed that is moved by grinding head 2 to adjust , it is mobile must be faster, milling time is that residence time in the same area is shorter；It is mobile must be slower, milling time i.e. exist Residence time in the same area is longer.It is so as to be ground by differentiation, i.e., the region grinding of thickness thickness is more, so as to So that the difference of original thickness reduces in wafer after differentiation grinding, achieve the purpose that to improve uniformity.

Mobile route can have three kinds.The first is the circular arc path shown in Fig. 4, that is, connects the shaft 20 of grinding head 2 Swung along origin 21, the scope of swing is from an edge to another edge for the wafer 1 in rotation.By path in figure The by stages 22 such as 8 are divide into, each section can set different pressure and translational speed.Second is shown in Fig. 5 The straight line path along 1 radius of wafer, that is, connect grinding head 2 shaft 20 moved back and forth along itself direction, mobile scope It is from the center of circle to edge of the wafer 1 in rotation.Path be divide into the by stages 22 such as 6 in figure, each section can be set Put different pressure and translational speed.The third is the straight line path along 1 diameter of wafer shown in Fig. 6, that is, connects grinding head 2 Shaft 20 moved back and forth along itself direction, mobile scope is from an edge of the wafer 1 in rotation to being symmetrical with circle Another edge of the heart.Path divide into the section 22 of 6 not deciles, each section can set different pressure in figure And translational speed.Fig. 7 is the first, the comparison schematic diagram in second and the third path.

The number in the section 22 of these three path subregions and the size (start-stop position) in each section 22 are according to before processing It is fixed that the distribution of 1 inner film thickness of wafer of measurement comes.If some 22 thickness of section is partially thick, as long as just increasing the pressure in the section 22 Power or reduction translational speed (increasing the time) can increase amount of grinding.Thickness so between the different sections 22 of before processing The difference of degree can be reduced, so as to achieve the purpose that to improve uniformity.During subregion, make film of the score in same section 22 as far as possible Thickness be amount that is close, then being ground again according to target thickness to determine each section 22 to need, and need what is used Pressure and translational speed.When pursuit 1 inner film thickness homogeneity of wafer is optimal, then the target thickness in each section 22 just should It is the same.Differentiation so by the selectivity of subregion is ground, it is possible to which the final thickness for reaching each section 22 is one Sample or as close possible to.But also having this possibility, i.e., the target thickness in each section 22 can be different.Even if In this way, the differentiation by the selectivity of subregion is ground, the final thickness in each section 22 can also reach or as close possible to every A target thickness of oneself of section 22.The number and size in section 22 theoretically can use by oneself and increase or decrease, however but by To the limitation of 2 size of grinding head,【017】Specific explanation can be provided.

The size of grinding head 2 is influential on the precision of uniformity and the processing speed of whole wafer 1 that can reach. Situation Fig. 8 shows two kinds of grinding heads 2 of different sizes by two adjacent intervals (22-1 and 22-2).Grinding head 2 itself There is size, a transition is had when it is from left to right moved to next section 22-2 from previous section 22-1. The right side that this transition starts from grinding head 2 has just enter into next section 22-2, end at grinding head 2 left side leave it is previous The size in this transition section of section 22-1. is exactly exactly the size of grinding head 2.The pressure of grinding head 2 in this transition section Power and translational speed are to influence the two adjacent sections (22-1 and 22-2) at the same time, if the two sections (22-1 and 22-2) requirement to amount of grinding is different, because can not be to the two sections (22-1 and 22- in this transition section 2) different pressure and translational speed are implemented respectively so as to reach different amount of grinding, therefore the amount of grinding in transition section is with regard to only Median can be taken in the different required values of two sections (22-1 and 22-2), i.e. accuracy will be sacrificed.So to improve The precision of even property, transition section will be small, i.e., the size of grinding head 2 will be smaller.But grinding head 2 is smaller, grinding efficiency is just It is lower, the time of the processing of whole wafer 1 will be spun out significantly.And grinding head 2 is smaller, also implies that and be attached on grinding head 2 Grinding pad 3 is also smaller, then and for same amount of grinding, the service life of smaller grinding pad 3 also can be shorter, such that Equipment, which is stopped, replaces the number increase of grinding pad 3, so that the time that equipment can be used in processing is also short.So final still will Equalization point is found between uniformity precision and processing speed (yield) to determine the size of grinding head 2.

Influence of the size based on above-mentioned grinding head 2 to the uniformity precision and processing speed that can reach, Fig. 9 are shown A kind of processing method, the i.e. first step first carry out rough uniformity with slightly large-sized grinding head 2 and improve, second step with compared with The grinding head 2 of small size improves to carry out fine uniformity.Notice that the mobile route mode that this two step uses can be the same, Can be different.The first step employs the first path (circular arc) in Fig. 9, and second step employs the third path, and (straight line is straight Footpath).Figure 10 shows a kind of two grinding heads 2 of different sizes while on wafer 1 move the mode of grinding, this side Advantage of the formula compared to Fig. 9 is that processing time can be shortened.Two grinding heads 2 of Figure 10 all employ identical second of path (straight line Radius), but as long as being designed to work as, collided when moving two grinding heads 2, different mobile route sides can also be respectively adopted Formula.

The beneficial effects of the utility model are to increase substantially IC chip by the differentiation grinding of selectivity to give birth to The uniformity of the film thickness in wafer 1 after production. art such as chemical mechanical grinding, makes it meet the rigors of advanced node. The differentiation grinding of selectivity divides abrasion path according to the distribution of the film thickness of the wafer 1 measured by before processing The size (start-stop position) in area, the number in section 22 and each section 22 is the reality of thickness in the wafer 1 measured according to before processing Border is distributed to define.Differentiation grinding can so reach that to increase substantially film thickness equal in addition with targetedly subregion The requirement of even property.Furthermore since the utility model greatly improves film thickness uniformity, typical chemical-mechanical grinding device The requirement of the film thickness uniformity reached to needs can be loosened, and so need not continue to more divide grinding head 2 Area, so as to avoid the equipment cost brought therefrom and the lifting of production cost.And since the utility model can be realized Selection grinding, cleaning and dry integration, it is possible to being integrated into typical chemical-mechanical grinding device.

Brief description of the drawings

Fig. 1 is the side view of chemical-mechanical grinding device.

Fig. 2 is the cross section of the grinding head 2 in chemical-mechanical grinding device and its subregion air bag 8 on wafer 1 Corresponding control area.

Fig. 3 is the side view and top view of the described equipment of the utility model.

Fig. 4 is the arc-shaped scanning pattern of the described selective differentiation grinding of the utility model.

Fig. 5 is the linear radius scanning pattern of the described selective differentiation grinding of the utility model.

Fig. 6 is the linear radius scanning pattern of the described selective differentiation grinding of the utility model.

Fig. 7 is the comparison in three kinds of paths of the described selective differentiation grinding of the utility model.

Fig. 8 for the described different size of grinding head 2 of the utility model move through two adjacent sections (22-1 and 22-2)

Fig. 9 is that the differentiation of described the making choice property of substep using different size grinding head 2 of the utility model is ground Mill.

The described differentiation using making choice property while different size grinding head 2 of Figure 10 the utility model is ground Mill.

Embodiment

3,4,5,6 pairs of specific embodiment of the present utility model are further described below in conjunction with the accompanying drawings.

The first step is loaded on wafer 1 to plummer 14.The size of plummer 14 is more slightly larger than wafer 1, and can be existed with vacuum Wafer 1 is firmly adsorbed on plummer 14 in process of lapping.

Second step is selective differentiation grinding.Grinding head 2 equipped with grinding pad 3 can carry hairbrush from what is usually stored 15 sink moves on to the top of wafer 1 and declines 1 surface of contact wafer.Wafer 1 and grinding head 2 start rotation, chemical abrasive material 4 at the same time 1 surface of wafer is flowed to from top.Grinding head 2 can be in movement in addition to rotation.Such as Fig. 4, Fig. 5 or Fig. 6, movement can be arc-shaped Path or rectilinear path.The actual distribution of thickness is divided into several areas in the wafer 1 that path is measured according to before processing Between 22, corresponding pressure and translational speed are set in each section 22.Optical film thickness measuring instrument 19 can be with process of lapping Measured in real time, the change of instantaneous feedback thickness, one can adjust 22 number of section and size immediately, and two can reach mesh Stop grinding in time when marking thickness.

3rd step is the cleaning and drying of wafer 1, and simultaneous grinding pad 3 can be scraped new and cleaning.After grinding, grinding head 2 can leave 1 surface of wafer, and the cleaning brush 16 for usually depositing in the polyvinyl chloride synthetic material of sink can move on to the top of wafer 1 Decline 1 surface of contact wafer again.Wafer 1 and cleaning brush 16 keep rotation at the same time, and chemical reagent 17 and deionized water 6 can be from tops 1 surface of wafer is flowed to successively.Cleaning brush 16 can be swept back and forth in addition to rotation on 1 surface of wafer.After cleaning, cleaning brush 16 Return to the sink of storage.Plummer 14 starts to rotate at a high speed, and the nitrogen 18 for being subject to spray room temperature or high temperature on 1 surface of wafer is done It is dry.It after grinding head 2 leaves 1 surface of wafer, can first move on at correction-plate 7, be contacted with correction-plate 7 and rotation carries out grinding pad 3 Scrape new.Also stored in the sink when correction-plate 7 is flat.Grinding head 2 returns to the sink with hairbrush 15 usually stored afterwards, first Contacted with hairbrush and grinding pad 3 is cleaned in rotation, be just detained start in the sink until grinding next time afterwards.

4th step is 1 thickness measure of wafer and possible grinding of doing over again.Wafer 1, can be on plummer 14 by after drying Film thickness is measured with optical film thickness measuring instrument 19.If the uniformity of film thickness is not reaching to requirement, can immediately begin to return Work is ground (since second step).

5th step is 1 removal of wafer, will grind the wafer 1 finished and be removed from plummer 14, and begin preparing for loading Next piece of wafer 1.

Claims (8)

1. a kind of equipment for improving wafer inner film thickness uniformity, wafer which includes placing upward, flow to crystalline substance The chemical abrasive material of circular surfaces, one or more diameters the posting between 10~40 millimeters being ground in crystal column surface are ground The grinding head of pad is ground, the route that grinding head passes through is divided into several sections, and the pressure and sweep speed in different sections are different.

2. equipment according to claim 1, it is characterized in that will grind, cleaning, dry and thickness measure is incorporated in same set Standby interior completion.

3. equipment according to claim 1, it is characterized in that the path that grinding head moves on the wafer surface have it is arc-shaped.

4. equipment according to claim 1, it is characterized in that the path that grinding head moves on the wafer surface has along radius Linear.

5. equipment according to claim 1, it is characterized in that the path that grinding head moves on the wafer surface has along diameter Linear.

6. equipment according to claim 1, it is characterized in that the number in section and the size in each section are according to before processing The actual distribution of thickness determines in the wafer of measurement.

7. equipment according to claim 1, it is characterized in that successively by the grinding head of multiple and different diameters crystal column surface into Row grinding, can use identical or different mobile route.

8. equipment according to claim 1, it is characterized in that the grinding head of multiple and different diameters is placed on wafer table at the same time Face is ground, and can use identical or different mobile route.