CN1154161C

CN1154161C - Plasma processing apparatus

Info

Publication number: CN1154161C
Application number: CNB981265537A
Authority: CN
Inventors: 松村浩
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 1997-12-25
Filing date: 1998-12-25
Publication date: 2004-06-16
Anticipated expiration: 2018-12-25
Also published as: KR100309524B1; JPH11186238A; KR19990063352A; CN1226740A; TW442867B

Abstract

A parallel-plate plasma processing apparatus includes an upper electrode and a lower electrode disposed below and extending parallel to said upper electrode. The lower electrode serves as a semiconductor wafer stage for supporting a wafer thereon. A plasma extension member is disposed immediately radially outwardly of an outer circumferential edge area of the semiconductor wafer on the lower electrode. The plasma extension member is made of a semiconductor material having a specific resistance kept in a predetermined range. A plasma is generated between the upper and lower electrodes stably in a region covering the entire surface of the semiconductor wafer.

Description

Plasma processing apparatus

Technical field

The present invention relates to plasma processing apparatus, particularly be used for the parallel-plate plasma processing unit of plasma etching semiconductor wafer.

Background technology

When by parallel-plate (plate electrode) plasma processing apparatus process semiconductor wafers, if the member that is arranged on the semiconductor wafer neighboring radially outwardly is by making as the insulating material of pottery, quartz etc., plasma has the neighboring area of the interior zone radially that is positioned at insulating component so.Therefore, at the plasma that the center and the neighboring area of semiconductor wafer produce different conditions respectively, cause in the plasma treatment performance of the neighboring area of semiconductor wafer plasma treatment poor performance than the central area of semiconductor wafer.In view of above shortcoming, attempted by closely being provided with radially outwardly in the semiconductor wafer neighboring by making different plasma treatment performance class homogenizing with plasma extension member that the same material of semiconductor wafer is made.

Fig. 1 of accompanying drawing shows conventional parallel-plate plasma processing unit.As shown in Figure 1, conventional parallel-plate plasma processing unit has a plasma processing chamber 1, the top electrode 3 that comprises ground connection, top electrode insulator 2 around top electrode 3, be arranged under the top electrode and with extend the bottom electrode 6 that supports the semiconductor wafer 8 on it as wafer station with it abreast, bottom electrode 6 be connected to high-frequency electrical energy is provided high frequency electric source 7 so that high frequency electric source to be provided thus, bottom electrode insulator 5 around bottom electrode 6, the next-door neighbour is arranged on the peripheral plasma extension member 4 that the semiconductor wafer neighboring is made by semi-conducting material radially outwardly on the bottom electrode 6, is used to increase the uniformity of semiconductor wafer 8 lip-deep plasma treatment.When semiconductor wafer 8 was placed on the surface of bottom electrode 6, plasma generation gas was introduced in the plasma processing chamber 1.After the pressure stability of the plasma generation gas in the plasma processing chamber 1, high frequency electric source 7 is provided to bottom electrode 6 with high-frequency electrical energy, produces plasma between bottom electrode 6 and top electrode 3.Surface by the plasma etching semiconductor wafer 8 that so obtains.

Fig. 2 of accompanying drawing and 3 shows the distribution of each electric field strength of the ion sheath of the plasma that is used for corroding semiconductor wafer 8 in the plasma processing apparatus shown in Figure 1 with different plasma expansion 4-2,4-3 respectively.

In Fig. 2, plasma expansion 4-2 has the big resistance that is almost insulating component.Because plasma expansion 4-2, the zone that produces plasma does not fully extend to the external periphery region of semiconductor wafer 8, can not provide uniform electric field on the neighboring of semiconductor wafer 8 and central area.Therefore, the corrosive nature on the periphery area of semiconductor wafer 8 is lower than the corrosive nature on the central area of semiconductor wafer 8.

In Fig. 3, the conductivity of plasma expansion 4-3 is greater than plasma expansion 4-2.Because plasma expansion 4-3, the zone that produces plasma is in the periphery area of semiconductor wafer 8 radially extends outwardly into zone above the plasma expansion 4-3.The central area of semiconductor wafer 8 is lower than the electric field strength of the periphery area of semiconductor wafer 8.Though the etching characteristic to the periphery area of semiconductor wafer 8 improves, the etching characteristic of the central area of semiconductor wafer 8 reduces.

Summary of the invention

Therefore an object of the present invention is to provide a kind of plasma processing apparatus, can on the whole surface of semiconductor wafer to be processed, produce plasma with uniform electric field intensity distributions, during process semiconductor wafers, has the stable generation zone that remains unchanged, so plasma processing apparatus has effective and uniform corrosive power to the whole surface of semiconductor wafer.

According to the present invention, a kind of parallel-plate plasma processing unit is provided, comprise top electrode, be arranged on below the top electrode and the bottom electrode that extends in parallel with it, bottom electrode works to support the semiconductor wafer stage of wafer on it, with the plasma extension member on the zone radially outward that is arranged on the bottom electrode with the periphery area next-door neighbour of semiconductor wafer, the plasma extension member is made to the semi-conducting material in the 15 Ω cm scopes at 1 Ω cm by its resistance, the plasma extension member comprises the peripheral plasma extension member around the periphery area of circular semiconductor wafers, the plasma extension member that wherein goes in ring has upper surface that embeds semiconductor wafer surface and the inside step shape part in footpath that extends under the periphery area of semiconductor wafer, prevent that thus described bottom electrode is exposed to the plasma that produces between top electrode and the bottom electrode, the inside step shape part in wherein said footpath is thinner than the thickness of semiconductor wafer.

When using the plasma processing apparatus process semiconductor wafers, because the heat that plasma transmits, the plasma extension member of being made by semi-conducting material its appointment resistance in time reduces.If the appointment resistance of plasma extension member is very high under the normal temperature, it is above up to the plasma treatment of finishing semiconductor wafer to specify resistance will remain on certain rank so, and the zone that produces plasma so can not extend to the periphery area of semiconductor wafer.If the appointment resistance of plasma extension member is lower than another certain rank, so because the plasma extension member passes electric field from bottom electrode, so the plasma extension member allows plasma diffusion to arrive than in the big zone of the size of semiconductor wafer.According to the present invention, the plasma extension member has the appointment resistance that remains in certain scope, and have certain shape and the structure that is used for producing all even stable plasma, an all even thus whole surface of corroding semiconductor wafer effectively on the whole surface of semiconductor wafer.

With reference to the accompanying drawing that shows example of the present invention, above and other purpose of the present invention, feature and advantage will become obviously from following specification.

Description of drawings

Fig. 1 is the profile of conventional parallel-plate plasma processing unit;

Fig. 2 shows the distribution of the electric field strength in the ion sheath of the plasma that produces in the plasma processing apparatus shown in Figure 1 with different plasma expansion 4-2 respectively.

Fig. 3 shows the distribution of the electric field strength in the ion sheath that produces in the plasma processing apparatus shown in Figure 1 with different plasma expansion 4-3 respectively.

Fig. 4 is the profile according to the parallel-plate plasma processing unit of the embodiment of the invention, there is shown the distribution of electric field strength in the ion sheath of the plasma that produces in plasma processing apparatus; And

Fig. 5 is the profile of parallel-plate plasma processing unit according to another embodiment of the present invention.

Embodiment

Fig. 4 shows the section according to the parallel-plate plasma processing unit of the embodiment of the invention.Except the plasma extension member, parallel-plate plasma processing unit shown in Figure 4 is identical with the parallel-plate plasma processing unit shown in Fig. 1-3 basically.In Fig. 4, the distribution of the ion sheath internal electric field intensity of the plasma of generation is also shown in the plasma processing apparatus.Research to Fig. 4 discloses the zone that is to produce plasma with the conventional equipment difference shown in Fig. 2 and 3, it is plasma slab, it is by the surface that radially extends to plasma extension member 4-4 on the surface of semiconductor wafer 8, and this expression plasma is all even on the whole surface of semiconductor wafer 8 stably to be produced.

According to the present invention, make at the semi-conducting material of the silicon materials of 1 predetermined Ω cm in the 15 Ω cm scopes by its resistance by the plasma extension member of 4-4 representative among Fig. 4.The number range of the appointment resistance of plasma extension member 4-4 is determined on the basis of experimental result.If the appointment resistance of plasma extension member is greater than 15 Ω cm, plasma slab can radially outward not extend to the periphery area of semiconductor wafer 8 fully so.On the contrary, if the appointment resistance of plasma extension member less than 1 Ω cm, it is overseas that plasma slab will be radially outward excessively extend to the outer perimeter zone of semiconductor wafer 8 so.No matter whether the appointment resistance of plasma extension member 4-4 less than 1 Ω cm or greater than 15 Ω cm, can not obtain from the central area of semiconductor wafer 8 to the uniform electric field intensity distributions of periphery area, as shown in Figure 4.Plasma extension member 4-4 comprises the belt plasma expansion around circular semiconductor wafers 8.Plasma extension member 4-4 has the upper surface that embeds semiconductor wafer 8, and described upper surface extends radially outwardly from next-door neighbour's semiconductor wafer 8.Peripheral plasma extension member 4-4 width is 20mm.Plasma extension member 4-4 comprises annular construction member or a plurality of member that is set to annular of individual unit.

Fig. 5 shows the section of parallel-plate plasma processing unit according to another embodiment of the present invention.Be similar to the plasma extension member 4-5 of plasma extension member 4-4 shown in Figure 4 except having the resistance of appointment, member 4-5 has the inside step shape part in footpath that is thinner than semiconductor wafer 8 thickness.

The inside step shape part in footpath of gas ions extension member 4-5 extends to the periphery area of bottom electrode 6 semiconductor-on-insulator wafers 8.The surface that the inwardly step-like thin part in footpath prevents bottom electrode 6 by the periphery area of semiconductor wafer 8 and do not have this between the inner circumference area of plasma expansion 4-5 of step shape part issuable space be exposed to plasma.

Show in every kind of parallel-plate plasma processing unit at Figure 4 and 5, bottom electrode 6 is covered by bottom electrode insulator 5, and comprises surperficial anodised aluminium sheet, and top electrode 3 is covered by the top electrode insulator, and comprises the silicon plate that is parallel to bottom electrode 6.Semiconductor wafer 8 to be processed is placed on the bottom electrode 6.With the difference speed of 30sccm (standard cubic meter of per minute) and 70sccm with CF ₄And CHF ₃Be incorporated in the plasma processing chamber 1 as plasma generation gas.After the pressure of plasma generation gas is stablized in plasma processing chamber 1, concussion frequency and 1 with 13.56MHz, the high-frequency electrical energy of the output level of 500W is applied to bottom electrode 6 by high frequency electric source 7, produces plasma in the space between bottom electrode 6 and top electrode 3 thus.At this moment, plasma produces on the surface of semiconductor wafer 8, also produces on the surface of plasma expansion 4-4,4-5.

Various different plasma processing unit use different systems to apply high-frequency electrical energy.For example, some plasma processing apparatus not only is applied to bottom electrode with high-frequency electrical energy and also is applied to top electrode.Yet principle of the present invention is also to be suitable for this different plasma processing apparatus.

Though use the term of appointment to introduce the preferred embodiments of the present invention, these explanations only are the diagram purpose, should be understood that can make in the spirit or scope of claims below not breaking away to revise and distortion.

Claims

1. parallel-plate plasma processing unit comprises:

Top electrode;

The bottom electrode that is arranged on below the top electrode and extends in parallel with it, described bottom electrode play semiconductor wafer stage and are used to support wafer on it; And

Be arranged on the bottom electrode plasma extension member on the zone radially outward with the periphery area next-door neighbour of semiconductor wafer, described plasma extension member is made to the semi-conducting material in the 15 Ω cm scopes at 1 Ω cm by its resistance,

Described plasma extension member comprises the peripheral plasma extension member around the periphery area of circular semiconductor wafers, wherein

Described belt plasma extension member has upper surface that embeds semiconductor wafer surface and the inside step shape part in footpath that extends under the periphery area of described semiconductor wafer, prevent that thus described bottom electrode is exposed to the plasma that produces between described top electrode and the described bottom electrode

The inside step shape part in wherein said footpath is thinner than the thickness of semiconductor wafer.

2. according to the parallel-plate plasma processing unit of claim 1, wherein said peripheral plasma extension member has a width that extends radially outwardly from semiconductor wafer, and described width is 20mm.

3. according to the parallel-plate plasma processing unit of claim 1 or 2, wherein said semi-conducting material comprises silicon.